Nicotinamide Mononucleotide (NMN)

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    A photo depicting the exact instance when a white powdery substance is spilling from a tall, elegant white packet. The 'NMN' label on the packet is sharply in focus.

    Nicotinamide Mononucleotide (NMN and β-NMN) is a compound found naturally in the cells of our bodies and is integral to several cellular processes. NMN is a direct precursor to NAD+, a vital coenzyme essential for a myriad of cellular functions. The levels of NAD+ are known to decline as we age, and this decline is associated with aging and various age-related diseases. It has been shown in several clinical trials that by supplementing with NMN, we can boost the levels of NAD+ in the body, potentially counteracting age-related cellular decline and improving overall health. Preliminary studies, mainly in mice, suggest that NMN supplementation could offer a range of health benefits, such as enhanced energy metabolism and improved DNA repair, indicating its potential role in slowing the aging processes.

    However, while NMN shows significant promise, comprehensive studies determining its long-term safety, effective dosage, and potential side effects in humans are still in progress. NMN is also present in several food sources, including broccoli, cabbage, cucumber, avocados, and edamame, but only in small quantities.

    NMN and its impact on longevity are at the cutting edge of anti-aging research, with new discoveries and insights emerging regularly, deepening our understanding of the aging process and potential interventions to extend health and lifespan.

    Sources of NMN in Food[edit | edit source]

    NMN is naturally present in a variety of foods, albeit in relatively small quantities. Here is a list of some foods known to contain NMN, along with their respective NMN content. [1]

    Food Type Name NMN Content (mg/100g-Food)
    Vegetable Edamame 0.47–1.88
    Broccoli 0.25–1.12
    Cucumber Seed 0.56
    Cucumber Peel 0.65
    Cabbage 0.0–0.90
    Fruit Avocado 0.36–1.60
    Tomato 0.26–0.30
    Other Mushroom 0.0–1.01
    Meat Beef (raw) 0.06–0.42
    Seafood Shrimp 0.22

    While these foods can contribute to NAD+ levels through the provision of NMN, the quantities present are relatively small, and it is currently unclear whether dietary intake alone can significantly impact NAD+ levels in the body. Therefore, research into NMN supplementation is ongoing to explore its potential in maintaining or elevating NAD+ levels and mitigating age-related decline.

    Legal[edit | edit source]

    European Union (EU)[edit | edit source]

    In the European Union, the classification and regulation of substances are often determined by their intended use and the claims made by the manufacturer or distributor. As of the latest update, Nicotinamide Mononucleotide (NMN) is classified as a chemical in the EU and has not been approved for human consumption. This classification is due to the EU's stringent regulations surrounding novel foods and substances, emphasizing consumer safety.

    While NMN is not approved for human consumption in the EU, consumers may come across NMN products online that appear to be marketed for human use. However, these are officially sold either as chemicals for research and laboratory purposes or as supplements for animals, including dogs and cats. It is important for consumers to recognize the legal status and potential risks of such unapproved substances.

    United States (US)[edit | edit source]

    In November 2022, the US Food and Drug Administration (FDA) issued a statement saying that NMN may not be sold as a supplement, citing its status as being under investigation as a drug. This development is a reversal of the FDA's previous decision to allow its sale as a new dietary supplement (NDI). The reason for the reversal is unknown, but in December 2021, Metro International Biotech, a startup pharmaceutical company that has developed the NMN formulation MIB-626, wrote to the FDA: "As a company that has instituted publicly available clinical trials on ß-NMN, we request that FDA take the preclusion provision … seriously to protect the rights of companies that have spent significant time and research to develop drug products from competition from dietary supplements". According to Insider, the FDA confirmed that it had considered Metro's request. [2]

    Different Forms of NMN[edit | edit source]

    Nicotinamide Mononucleotide (NMN) exists in two stereoisomeric forms, α-NMN and β-NMN, which have the same molecular formula but differ in the spatial arrangement of atoms. Recent advancements in NMN supplementation have led to the development of various formulations aimed at enhancing the compound's bioavailability and efficacy.

    β-NMN[edit | edit source]

    β-NMN is the biologically active form of NMN, predominantly utilized in scientific studies and supplements. It is integral in the biosynthesis of Nicotinamide Adenine Dinucleotide (NAD+), a vital coenzyme involved in numerous cellular processes, including energy metabolism, DNA repair, and cellular aging. When references are made to NMN in the context of supplementation or scientific research, it typically pertains to β-NMN due to its biological significance and activity.

    α-NMN[edit | edit source]

    α-NMN, on the other hand, does not participate in NAD+ biosynthesis and lacks the biological activity and associated health benefits of β-NMN. It is not the focus of NMN-related research or supplementation.

    Liposomal NMN[edit | edit source]

    Liposomal NMN is a form of NMN that is encapsulated within liposomes to enhance stability and bioavailability. This dietary supplement is available on the market and is being explored for its potential to increase the effectiveness of NMN supplementation. However, as of the latest updates, there are no published clinical studies specifically validating the benefits and efficacy of liposomal NMN, which means that while the theoretical advantages are promising, they have not yet been confirmed by scientific research.

    MIB-626[edit | edit source]

    Graphs showing the effect of NMN on NAD+ levels. The left graph indicates no change in NAD+ levels with placebo over 14 days. The middle graph shows a doubling of NAD+ levels with a daily dose of 1,000 mg NMN. The right graph demonstrates a tripling of NAD+ levels with a twice-daily dose of NMN.
    MIB-626 doses of 1,000 mg taken once daily over 14 days doubles NAD+ levels (middle graph). When taken twice daily, MIB-626 triples NAD+ levels (right graph). The placebo capsules had no effect on NAD+ levels (left graph). [3]

    MIB-626, developed by Metro International Biotech, is a microcrystalline form of NMN. This formulation may offer enhanced stability, solubility, or bioavailability compared to the regular crystalline form of NMN, potentially optimizing the efficacy of NMN supplementation. MetroBiotech plans to bring MIB-626 on the market as drug, not as dietary supplement. For that reason, several clinical trials are ongoing evaluating the effects and safety of MIB-626 on humans.

    Early results have indicated that a dosage of 1000 mg over 14 days can raise NAD+ levels (AUClast) about factor 1.7, and 2000 mg can increase by factor 3.7 above baseline in overweight or obese adults.[3]

    Reduced NMN (NMNH)[edit | edit source]

    Reduced Nicotinamide Mononucleotide (NMNH) is a novel, potentially more effective NAD+ precursor.

    NMN-HAP[edit | edit source]

    NMN-HAP is a hydroxyapatite-based nano-drug delivery system for nicotinamide mononucleotide that showed significantly enhancing NMN bioavailability and replenishing NAD+ levels in mice.[4] NMN-HAP is currently not available as supplement.

    Metabolism of NMN[edit | edit source]

    Bioavailability[edit | edit source]

    Levels of NAD+ and NAMN in blood were increased by oral administration of 250mg NMN.
    Levels of NAD+ and NAMN in blood were increased by oral administration of 250mg NMN. NAD metabolome in blood was measured every 4 weeks. Three asterisks mean statistical significance: p-value < 0.001.[5]

    Bioavailability is a crucial factor in the effectiveness of any dietary supplement, including Nicotinamide Mononucleotide (NMN). It refers to the proportion of a substance that enters the circulation when introduced into the body and is thus able to have an active effect. In the case of NMN, bioavailability determines how much of the compound reaches the bloodstream and subsequently contributes to NAD+ biosynthesis. One of the main challenges with NMN bioavailability is its absorption and transportation within the body. When taken orally, NMN needs to be absorbed through the gastrointestinal tract, which can present barriers to its effective uptake.

    • Molecular Size: NMN's relatively large molecular size compared to other NAD+ precursors (like NR, or nicotinamide riboside) poses a challenge for its absorption in the gut.
    • Enzymatic Degradation: NMN can be subject to degradation by enzymes in the digestive tract, potentially reducing the amount that actually enters the bloodstream.

    To address these challenges, various strategies and formulations have been developed:

    • Liposomal Encapsulation: Liposomal NMN involves wrapping NMN molecules in a lipid layer, which can help protect them from degradation in the digestive system and enhance absorption.
    • Sublingual Administration: Taking NMN sublingually (under the tongue) is proposed to increase its bioavailability by allowing direct absorption into the bloodstream, bypassing the digestive system.
    • Microcrystalline Formulation: MIB-626, a microcrystalline form of NMN developed by MetroBiotech, is believed to offer enhanced stability and bioavailability.

    While various methods to enhance NMN’s bioavailability are being explored, conclusive evidence on the most effective form or administration method is still emerging. Current research is focused on understanding how different formulations affect NMN's absorption and utilization in the body. Future studies are expected to provide more insights and possibly lead to more effective NMN supplementation strategies.

    Effect[edit | edit source]

    • Taking 800 mg NMN per day increase blood cell NAD+ levels by ~43% in mild hypertension patients display significantly lower blood cell NAD+ levels.[6]
    • Taking 300 mg NMN per day increase serum NAD+/NADH ratio by ~38%.[7]
    • It is assumed that the NAD+ level increases continuously through the NMN intake until it reaches its maximum after 1-2 weeks.[Citation needed]
    After NMN Group Placebo Group NMN group
    NAD+ concentrate [µM] NAD+ concentrate [µM] NAMN
    Baseline After Factor Baseline After Factor After
    Whole blood, 250 mg/day[8] 12 weeks 0.176±0.063 1.07±0.16 6.1 0.194±0.081 0.53±0.12 2.7 3.51±1.86
    250 mg/day[5] 12 weeks ~22 ~38 1.72 ~21 ~22 ~1 ~1.45
    250 mg/day[9] 12 weeks 0.006 (mean) 0.026 (mean) (4.3)
    800 mg/day[6] (pmol/mg protein) 12 weeks 14.81±11.68 21.19±11.83 1.43 16.20±10.37 16.15±8.56 ~1

    Combination Therapy for Enhanced NAD+ Levels[edit | edit source]

    A variety of nutritional supplements are available in the market, which contains the compositions of NMN coupled with natural products. Despite this, the synergistic effects and transformation processes of NMN in such combinations are not fully understood.

    In a recent study, oral administration of NMN (500 mg/kg) was combined with either resveratrol (50 mg/kg) or ginsenosides (Rh2 & Rg3) (50 mg/kg) in C57BL/6 mice to assess the efficacy of these drug combinations. The results showed that the combination could increase NAD+ levels in specific mouse tissues compared to NMN alone:[10]

    • With Resveratrol: NAD+ levels increased approximately 1.6 times in the heart and 1.7 times in muscle tissue.
    • With Ginsenosides (Rh2 & Rg3): NAD+ levels in lung tissue improved by about 2.0 times.

    These findings suggest that combining NMN with specific natural products like resveratrol or ginsenosides may amplify the beneficial effects on NAD+ levels, offering new avenues for treating age-related diseases or conditions linked to decreased NAD+ levels in specific tissues.

    Clearance[edit | edit source]

    It is currently assumed that NAD+ levels return to baseline within 1-2 weeks after ceasing NMN administration.[Citation needed] In two clinical trials, NAD+ levels were measured four weeks after discontinuation of NMN and were found to be back to baseline.[5][9]

    Controversy about NMN as Direct Precursor[edit | edit source]

    NMN administration of NMN–HAP and free NMN increases plasma NAD+ and NR in mice
    NMN administration of NMN–HAP and free NMN increases plasma NAD+ and NR in mice[4]

    NMN is often advertised, for example by NMN suppliers, as a direct precursor to NAD+, purportedly making it more effective compared to other precursors like Nicotinamide Riboside (NR). However, NMN's role as a direct precursor is only effective when it is inside the cell. This raises questions about how NMN, when ingested or administered externally, enters the cell to contribute to NAD+ synthesis. The central controversy surrounding NMN as a precursor to NAD+ lies in its mechanism of cellular entry. While NMN is a direct precursor of NAD+ within the cell, the debate focuses on whether NMN can be directly absorbed by cells or if it must first be converted to NR. In that case, NR might have an advantage over NMN, as NMN would require one additional conversion step compared to NR.

    1. Direct Transport Mechanism: One hypothesis suggests that NMN can directly enter cells through specific transporters. The Slc12a8 transporter in the aged mouse ileum has been suggested to facilitate NMN's direct absorption[11]. However, this idea has faced challenges due to conflicting research findings[12][13], and the functionality of Slc12a8 in humans has yet to be conclusively determined.
    2. Dephosphorylation to NR: An alternative and currently more widely accepted theory proposes that NMN is not directly utilized by cells. Instead, it is first converted to Nicotinamide Riboside (NR) through dephosphorylation before cellular absorption. This conversion is mediated by enzymes like CD73. Once inside the cell as NR, it is then phosphorylated into NMN[13][14].

    While direct transportation into the cell and dephosphorylation to NR can coexists, studies in mice indicate that orally ingested NMN is predominantly converted to NR in the intestinal tissue before absorption, challenging the view of NMN as a direct precursor to NAD+[15].

    Potential Longevity Benefits[edit | edit source]

    NMN supplementation has been associated with several potential benefits, primarily due to its role as a precursor to NAD+, a crucial coenzyme involved in various cellular processes. Here are some potential benefits based on preliminary research:

    Prospects of increasing NAD+ by NMN[16]
    Potential health benefits in mouse models Results of published human clinical trials

    A simplified diagram showing the relationship between NMN and NAD+ in a mouse model. An arrow points downward from 'NMN' to a circular graphic with a silhouette of a mouse, inside which is 'NAD+' with an upward-pointing red arrow, indicating an increase in NAD+ levels when NMN is administered.
    • Brain: improved brain function, protected from neurodegeneration[17][18][19][20][21], enhanced new myelin generation[22]
    • Lung: prevented pulmonary fibrosis, improved respiratory system function[23]
    • Liver: improved liver function, reduced hepatic steatosis, increased capacity to regenerate[24][25]
    • Heart: protected cardiomyocytes from injury caused by tachycardia[26][27][28]
    • Eye: exerted neuroprotective effects on photoreceptors[29][30]
    • Muscle: reduced atrophy, enhanced mitochondrial function and increased physical activity[29][31]
    • Vasculature: protected vasculature[32][33][34], increased capillary density, neovascularization, blood flow[35]
    • Inflammageing: improved immune cell function, reduced inflammation[36][37][38]
    • Skin: protected the skin from photodamage caused by UVB irradiation[39]
    • Reproduction: improved oocytes quality[40][41], restores fertility[41], increased the number of sperm[42]

    A simplified diagram showing the relationship between NMN and NAD+ in human. An arrow points downward from 'NMN' to a circular graphic with a silhouette of a person, inside which is 'NAD+' with an upward-pointing red arrow, indicating an increase in NAD+ levels when NMN is administered.
    • Safety: basically safe under the existing intervention dose and time
    • Sleep quality: no significant improvement[43]
    • Muscle: prevented aging-related muscle dysfunctions and improving physical performance[43][8][44][7]
    • Ear: improved the right auditory ability of old men[8]
    • Cognition: no significant improvement[8]
    • Diabetes: increased muscle insulin sensitivity, insulin signaling, and remodeling in prediabetic women[1]
    • Telomere: increased telomere length[45]
    • Hypertension: significantly lowers blood pressure in mild hypertensive adults[6]

    In Humans[edit | edit source]

    • Cellular Energy and Metabolism: By increasing NAD+ levels, NMN supplementation can potentially enhance cellular energy production and metabolism, leading to improved physiological functions and reduced age-related metabolic decline.
    • Cognitive Function: Some research indicates that NMN may have neuroprotective effects, potentially improving cognitive function and reducing the risk of neurodegenerative diseases by maintaining neuronal health and resilience.
    • Cardiovascular Health: NMN supplementation may offer cardiovascular benefits by improving blood flow and reducing the risk of age-related cardiovascular diseases, contributing to heart health and longevity.
    • DNA Repair: Enhanced NAD+ levels through NMN supplementation can support DNA repair mechanisms, potentially reducing DNA damage and the risk of mutation, which are associated with aging and cancer.
    • Insulin Sensitivity: NMN has been shown to improve insulin sensitivity, potentially reducing the risk of type 2 diabetes and metabolic syndrome, contributing to overall metabolic health.

    Safety and Dosage[edit | edit source]

    When considering NMN supplementation, it is crucial to understand the potential interactions and impacts of NMN. Here are some considerations based on current knowledge and research.

    Dosage[edit | edit source]

    Human studies have tested a range of doses, with some trials using up to 1,200 mg over 6 weeks. The longest study was about 250 mg over 24 weeks. However, the long-term safety, efficacy, and optimal dosage of NMN are still under investigation, and more comprehensive studies are needed to establish concrete guidelines for NMN supplementation.

    David Sinclair takes 1000 mg/day NMN in the morning.

    Safety[edit | edit source]

    When it comes to NMN (Nicotinamide Mononucleotide) supplementation, safety is a primary concern, especially given the relatively early stage of human studies in this area. The current body of research, mostly comprising animal studies and limited human trials, suggests that NMN is generally well-tolerated at various dosages. However, there are several important safety considerations to keep in mind:

    • Human Study Limitations: Most research on NMN has been conducted in animal models, primarily mice. While these studies are promising, human biology can respond differently, and the long-term effects of NMN in humans are still not fully understood.
    • Dosage and Tolerance: The tolerability of NMN appears to be dose-dependent. Human studies have tested a range of doses, with some trials using up to 1,250 mg per day or 2,000 mg per day of the specialized NMN formulation MIB-626. These studies have generally reported good tolerability, but individual responses can vary.
    • Interactions with Medications: The potential interactions between NMN and various medications are not yet fully understood. Individuals taking prescription medications, particularly those for chronic conditions, should consult with a healthcare provider before starting NMN supplementation.
    • Long-term Safety: The long-term safety of NMN supplementation is an area that requires further research. While short-term studies have shown promising results, the effects of prolonged NMN use over years or decades are not yet known.
    • Purity and Quality of Supplements: The market for NMN supplements varies widely in terms of product purity and quality. It is crucial to source NMN from reputable suppliers who provide third-party testing and quality assurance to ensure the product is free from contaminants and accurately labeled in terms of dosage.
    • Population-Specific Effects: Different populations, such as the elderly, those with chronic illnesses, or those with specific genetic backgrounds, may respond differently to NMN supplementation. Tailored studies are needed to understand these variable responses better.

    In summary, while NMN supplementation is an exciting area of research with potential health benefits, especially related to aging and metabolic health, it is essential to approach it with caution. Ongoing research and clinical trials will continue to inform safer usage guidelines and help identify the full spectrum of NMN's effects in humans.

    Side Effects[edit | edit source]

    Overall, there have been no serious side effects in humans clinical trials that have been due to the use of NMN. When taken at higher doses than intended, you could be facing side effects such as nausea, diarrhea, indigestion, and stomach discomfort. However, these are common side effects of supplements when taken in amounts that are too high.[46]

    Some individuals reported in NMN forums low energy and tiredness potentially caused by methyl donor deficiency (see next section).[47] The side effects can occur from the beginning or after a longer period of use.

    It is important to monitor for any adverse reactions, especially when starting supplementation or changing dosages.

    Methyl Donor Deficiency[edit | edit source]

    There is a theoretical concern that consuming NMN could deplete methyl groups in the body and might lead to a Methyl Donor Deficiency associated with symptoms such as low energy and tiredness. NMN is converted to NAD+ in the body, which can then be broken down into nicotinamide. Nicotinamide is then methylated by the liver to form N1-methylnicotinamide, which is excreted in the urine. This methylation process consumes a methyl group from S-adenosylmethionine (SAMe), the primary methyl donor in the body.

    For this reason, some individuals who take NMN also supplement with methyl donors such as Trimethylglycine (TMG) or Vitamin B Complex to ensure that they are not depleting their body's supply of methyl groups. Some individuals take methyl donors as a precautionary measure, while others may begin supplementation after experiencing sleepiness attributed to NMN.[47]

    However, there is no clear evidence yet as clinical trials are lacking. While the biochemical pathway is known, the actual impact of NMN supplementation on the global status of methyl groups is not well-established in humans. It would likely require substantial NMN consumption coupled with an insufficient intake of dietary methyl donors to significantly affect these groups. There could be also a compensatory mechanisms in place slowing down the conversion of NMN to NAD+ or the methylation of nicotinamide if methyl groups were being depleted.

    Types of NMN Administration[edit | edit source]

    Nicotinamide Mononucleotide (NMN) can be administered in various forms, each with its unique considerations. Below is a breakdown of the common types of NMN administration:

    • Oral Powder (Dissolved in Water): NMN powder can be dissolved in water and consumed as a drink. The benefit of this method, compared to capsules, is that the dosage can be easily adjusted, for example, reduced if side effects appear. In animal studies, particularly with mice, NMN is often mixed into the animals' drinking water.
    • Oral Powder (Mixed with Food): NMN powder can also be mixed with food items such as yogurt. This method is considered oral ingestion, similar to dissolving it in water, and subjects the NMN to the digestive process. Mixing NMN with food can be convenient for those who prefer not to take it sublingually or in capsule form and may help mask any unpleasant taste of the NMN powder when dissolved in water. However, the effectiveness and bioavailability of NMN when mixed with food have not been extensively studied, and the presence of other food components and the acidic environment might potentially influence the stability and absorption of NMN.
    • Capsule Form: NMN is encapsulated for easy consumption, offering a convenient and taste-neutral method. Like oral powder, capsules subject NMN to the digestive process. Capsule form is often used in clinical trials as it allows for precise dosing and is generally well-accepted by participants. It also enables the blinding of participants in placebo-controlled trials, maintaining the integrity of the study, as it is easier to make placebo capsules or tablets that are indistinguishable from the active ones.
    • Sublingual Powder: This form of NMN is taken by placing the powder directly under the tongue, allowing it to dissolve and be absorbed through the mucous membranes in the mouth. The general guideline is to hold the substance under the tongue for approximately 1 to 5 minutes to allow for adequate absorption through the sublingual gland. Some individuals believe sublingual administration offers better bioavailability due to direct absorption into the bloodstream, bypassing the digestive system. However, while this method is promoted in many YouTube videos, there is no evidence of any positive or negative effects and there is currently no clinical study utilizing sublingual administration. Furthermore, this method is relatively inconvenient, especially for those who might find the taste of sublingual powder too strong.

    Timing for Supplementation[edit | edit source]

    Our body has a natural rhythm where NAD+ levels fluctuate throughout the day rather than remaining constant, closely tied to our circadian rhythms.[48] NAD+ plays a crucial role in regulating our body's internal clock. The Sirt-1 gene, which is influenced by NAD+, signals our body when it's time to eat or sleep.[49]

    Dr. David Sinclair suggests to take NMN in the morning when the natural rise in NAD+ and Sirt-1 activity should happen. Taking NMN e.g. at night might disrupt the NAD+ cycle and potentially affecting the sleep or hunger. This can be especially beneficial for frequent travelers trying to adjust to a new time zone, as a morning dose of NMN can help reset the body's internal clock and reduce jet lag.[50]

    A recent RCT clinical trial investigated the effects of the time-dependent intake of NMN (250 mg/day) on older adults (≥ 65 years) over 12 weeks. Aging-induced insufficient physical activity and deterioration of physical function result in fatigue. This symptom frequently occurs among the elderly and has been complained by 27–50% of community-dwelling older adults in their daily life. Overall, NMN intake in the afternoon (in contrast to the morning) effectively improved lower limb function and reduced drowsiness in older adults. These findings suggest the potential of NMN in preventing loss of physical performance and improving fatigue in older adults.[43]

    Additionally, it's noteworthy that two MIB-626 trials utilized a twice per day administration regimen. This dosing schedule is significant because it could potentially offer more consistent NAD+ level support throughout the day, although the specific implications of this frequency in relation to circadian rhythms and overall efficacy remain an area for further research.[3][51]

    Stability and Storage[edit | edit source]

    NMN powders are thought to degrade into NAD+ when left at room temperature. However, this may be true for pure NMN supplements, some supplements use NMN in a stabilized form. This form has been shown to be more stable thus resulting in less breakdown at room temperature.[52]

    Humidity or water can have negative effects on NMN and result in the degradation of NMN into NAD+. This fact is not disputed and thus NMN powder should be stored in a dry place in a resealable container.

    In addition, scientists have tested NMN powders and found that these do not need to be kept in the refrigerator or freezer. The purity at 1 year when stored in a plastic bottle at room temperature was found to be 99.8%. Also a NMN manufacturer published NMN stability results when putting NMN into double pharmaceutical polyethylene bags. After 6 month under condition of 40℃ and 75% relative humidity the samples had > 99% purity.[53]

    However, it is advised if storing for the long-term (> 3 months), NMN supplements should be kept in the refrigerator to ensure its stability.

    Overall, NMN powders are stable when stored at room temperature, especially when provided in a stabilized form. However, they need to be kept away from high-humidity environments as water can speed up the degradation of NMN. So if you plan to consume the powder immediately (< 1–2 months) you do not need to store it in the refrigerator but if stored for> 3 months it is best to store it in the refrigerator.

    Always consult the manufacturer of you specific NMN supplements to obtain proper storage instructions for your product. If concerned, storing the NMN in the refrigerator does not have negative effects on the NMN and thus can be done.

    NMN appears to be stable in water; in one study 93%–99% of NMN was maintained intact in drinking water at room temperature for 7–10 days.[29]

    Synergistic Supplements in Conjunction with NMN[edit | edit source]

    While Nicotinamide Mononucleotide (NMN) itself is a promising compound in the realm of anti-aging and cellular health, its potential can be further enhanced when used in conjunction with other supplements. This section explores various nutraceuticals that may have synergistic effects when taken alongside NMN, potentially amplifying its benefits.[54]

    Stilbenes: Resveratrol and Pterostilbene[edit | edit source]

    Stilbenes, particularly resveratrol and pterostilbene, are non-flavonoid phenolic compounds extensively studied for their anti-inflammatory, antioxidant properties, and their role in combating age-related disorders like diabetes and cancer[55][56]. They are found naturally in grapes and berries, and studies have established their safety and bioavailability, with doses of resveratrol up to 5 grams and pterostilbene to 250 mg being well-tolerated[57][58].

    Despite their potential, resveratrol and pterostilbene have shown lifespan extension only in certain preclinical models, with the results being context-dependent and subject to debate[59]. Pterostilbene is particularly notable for its higher bioavailability (80%) compared to resveratrol (20%), and its efficacy in upregulating antioxidant enzymes like SOD and GR[60]. This difference in bioavailability is critical in modulating the SIRT1 pathway, with co-administration of the two potentially maximizing their collective benefits[61].

    Resveratrol's role in skin health, through its anti-angiogenic and wound-healing properties, is well-documented[62][63], while pterostilbene effectively mitigates inflammatory responses in various contexts[64][65][66][67].

    The relationship between resveratrol and the SIRT1 pathway is a key focus in experimental models, especially in the context of dosage and supplementation[68][69]. Although resveratrol has shown numerous health benefits, its direct activation of SIRT1 remains a subject of debate. Nonetheless, its indirect involvement in SIRT1 activation and its mimicry of caloric restriction effects suggest its potential as a metabolic modulator related to aging[70][71].

    Resveratrol and pterostilbene's potential in conjunction with NMN supplementation is particularly promising. Their combined use can lead to increased NAD+ levels in the heart and skeletal muscle, more so than NMN alone[10]. Resveratrol's ability to activate NMNAT1, thus increasing NAD+ levels and providing a substrate for SIRT1 activation, underscores the potential of these compounds in a targeted approach to delay or reverse aging signs[72]. Their co-administration with NR has also shown a dose-dependent increase in NAD+ levels in acute kidney injury patients, further supporting their combined use in age-related therapies[73][74].

    In summary, resveratrol and pterostilbene, especially when used in combination with NMN, represent a strategic orthomolecular approach to enhancing longevity and managing age-related diseases.

    CoQ10[edit | edit source]

    Coenzyme Q10 (CoQ10), also known as ubiquinol in its oxidized form, ubiquinone, is a crucial component in the mitochondrial electron transport chain. Its role in cellular energy production and as an antioxidant makes it integral to health, particularly in the context of neurodegenerative disorders, diabetes, cancer, fibrosis, and cardiovascular diseases[75]. CoQ10 supplementation, especially in disease states, is aimed at restoring antioxidant activity to correct homeostatic imbalances[76].

    CoQ10's cardiovascular protective qualities are well-established, with evidence showing its ability to improve hyperglycemia, hypertension, oxidative stress, and reduce the risk of cardiac events[77]. Notably, endogenous synthesis of CoQ10 declines with age, and higher mitochondrial levels have been linked to increased longevity. This connection is particularly evident in skeletal muscle health in the elderly, where higher plasma CoQ10 content correlates with improved muscle integrity and reduced levels of inflammatory markers such as TNF-α, IL-6, and CRP[78].

    The importance of CoQ10 extends to lipid metabolism, where it plays a key role in maintaining lipid integrity and preventing LDL oxidation, thereby offering protection against atherosclerosis[79]. Replenishing declining CoQ10 levels in aging individuals is essential to mitigate the risk of age-related diseases and reduce the burden of oxidative stress[80]. Studies have shown that CoQ10 supplementation, combined with dietary changes, can improve metabolic profiles in elderly men and women, reducing metabolic and cardiovascular risks[81].

    In the context of chronic fatigue syndrome (CFS), which shares several characteristics with aging such as inflammation and oxidative stress, CoQ10 and NAD+ supplementation have demonstrated synergistic effects. These supplements have been shown to decrease maximum heart rate post-exercise and improve fatigue symptoms, as well as enhance levels of NAD+/NADH, CoQ10, ATP, citrate synthase, and lipoperoxides[82][83].

    The antioxidant, anti-inflammatory, and age-mitigating effects of CoQ10 position it as a valuable supplement in an orthomolecular approach to combat the biological process of aging. This is especially true when considering its supportive role in enhancing NAD+ levels. However, further research is needed to fully elucidate the synergistic benefits of combining NAD+ precursors with CoQ10 supplementation in aging and age-related diseases.

    Trimethylglycine (TMG)[edit | edit source]

    Trimethylglycine (TMG), also known as betaine, was initially derived from the beetroot plant and is recognized for its osmoprotectant and anti-inflammatory properties. As a primary methyl group donor, TMG plays a significant role in DNA methylation processes, alongside other compounds like methionine and choline. The rate of DNA methylation is closely linked to the availability of these methyl donors[84]. TMG also acts to suppress various inflammatory expression profiles, including TNF-α, COX2, and NF-kB activity[85].

    The role of TMG extends to combating age-related pathologies. It does so by supporting optimal lipid and glucose metabolism, inhibiting inflammatory transcription processes, and reducing cellular ER stress[86]. One of the notable aspects of TMG's function is its influence on the methylation process, crucial for epigenetic regulation and genome stability, which are integral to healthy aging.

    A key consideration in the context of NAD+ supplementation is the impact on TMG levels. The degradation of NAD+ precursors, particularly nicotinamide (NAM), demands a higher consumption of TMG compared to choline, potentially depleting the available pool of methyl donors[87]. This elevated consumption of TMG during NAM degradation underscores the importance of supplementing with methyl donors when administering NAD+ precursors, especially NAM, to maintain balanced methylation[88].

    However, the specific effects of NMN or direct NAD+ conversion on methylation levels have yet to be thoroughly investigated. Therefore, concurrent supplementation of NMN, NAD+, or other NAD+ precursors along with TMG could be a strategic approach to prevent a decline in TMG levels. This co-supplementation may ensure the maintenance of proper methylation health and function, thereby supporting overall well-being and potentially mitigating age-related decline.

    Flavonoids: Quercetin, Fisetin, Luteolin/Luteolinidin, and Apigenin[edit | edit source]

    Flavonoids such as fisetin, quercetin, luteolin/luteolinidin, and apigenin have demonstrated significant health benefits, including potent senolytic activity.

    Fisetin and quercetin are known for their anti-cancer properties, particularly in inducing calcium-induced tumor apoptosis and improving cancer-related inflammatory profiles[89]. Fisetin, in particular, has shown strong senolytic effects in older and progeroid mice models, as well as in murine and human adipose tissues, contributing to improved lifespan and tissue homeostasis[90]. Its safety and efficacy are being investigated in Phase 2 clinical trials focusing on reducing inflammation and improving walking speed in frail elderly individuals (NCT03675724, NCT03430037). Fisetin also interacts with the NAD+/NADH age-related pathway, notably through SIRT1 activation, suggesting potential geroprotective effects in the context of NAD+/SIRT1/CD38 pathways, although more research is needed to establish concrete effects on longevity[91].

    Quercetin, structurally similar to fisetin, is also recognized as a senolytic agent with benefits in cardiovascular disease, neurodegeneration, inflammation, oxidative stress, cancer, and diabetes management. It is considered a geroprotective agent in in vitro models of premature aging[92][93]. Quercetin contributes to the modulation of the NAD+/SIRT1/CD38 axis by altering the NAD+/NADH ratio, activating SIRT1, and inhibiting CD38, thereby impacting metabolic disorders[94][95][96].

    Luteolin and its derivative luteolinidin have shown anti-inflammatory effects, particularly in skin aging, skin diseases, and cognitive functions[97]. They are implicated in the CD38 mechanism, acting as potent inhibitors and leading to an increase in available NAD+ levels[98][99]. Their potential in clearing cellular senescence, especially when used alongside NAD+ supporting compounds, highlights their role in longevity promotion[100].

    Apigenin, derived from parsley and chamomile, exhibits strong anti-inflammatory, antioxidant, and anti-carcinogenic properties. It reduces inflammatory mediators like COX2, IL6, and TNF-α[101], and upregulates antioxidant enzymes such as SOD, GPX, and GR[10.1080/10942912.2016.1207188]. Apigenin's anti-cancer activity is evident in its ability to downregulate key cancer pathways and sensitize tumor cells to chemotherapy[102]. It also attenuates metabolic complications and possesses anti-obesity effects[103][104][105]. Additionally, apigenin improves vascular endothelial function and structure, counteracting age-related changes due to oxidative stress[106].

    In the context of NAD+ supplementation, apigenin’s involvement with the SIRT1, NAD+, and CD38 axis is particularly notable. It enhances endogenous NAD+ levels by inhibiting CD38 and increasing the activation ratio of SIRT1 and NAD+/NADH, thereby reducing cellular senescence due to oxidative stress[107][108]. This strong inhibition of CD38 by apigenin makes it an integral part of strategies aimed at restoring age-related depletion of NAD+ levels, enhancing the effectiveness of NMN supplementation and overall geroprotective strategies.

    Carotenoids: Astaxanthin and Lycopene[edit | edit source]

    Carotenoids like astaxanthin and lycopene are renowned for their antioxidant and anti-inflammatory properties, playing a significant role in health and longevity (Figure 2).

    Astaxanthin is a powerful antioxidant carotenoid known for its ability to mitigate reactive oxygen species (ROS) and support mitochondrial integrity[109]. It has shown remarkable efficacy in activating SIRT1, which contributes to its longevity-promoting effects:

    • Neuroprotection: Astaxanthin has been demonstrated in vivo to alleviate oxidative stress in brain injury, upregulating Nrf2 and SIRT1 expression while decreasing pro-apoptotic factors, thus potentially reducing the risk of neuronal death[110].
    • Cardiac and Fibrotic Protection: It ameliorates the effects of a high-fat diet on cardiac and fibrotic damage through SIRT1 upregulation, inhibition of inflammatory cell mobility, and reduced collagen deposition, leading to less fibrosis post-injury[111][112].
    • Renal Tissue Protection: Astaxanthin also protects renal tissue post-injury through SIRT1 upregulation[113].
    • Boosting NAD+ Levels: Notably, a study combining NMN, astaxanthin, and blood orange extract in aging zebrafish demonstrated an enhanced ability to raise NAD+ levels, surpassing combinations of NR with astaxanthin or pterostilbene[10.1093/cdn/nzac047.054]. This finding suggests astaxanthin's potential in NAD+ boosting strategies and warrants further research on effective dosages and combinations in humans.

    Lycopene is another carotenoid with significant antioxidant and anti-inflammatory effects. It is known for improving various age-related conditions:

    • Physical Performance and Skin Aging: Supplementation with lycopene has been shown to enhance physical performance, combat osteoporosis, and improve skin aging, owing to its antioxidant properties[114].
    • Muscle Angiogenesis and Insulin Resistance: Lycopene activates SIRT1, which aids in muscle angiogenesis and the reversal of insulin resistance in age-related vascular decline[115].
    • Combination Therapy with NMN: In models of D-galactose-induced aging, a combination of NMN and lycopene showed superior results compared to NMN alone. It enhanced antioxidant enzyme activities, demonstrated senolytic abilities, upregulated Nrf2, and improved cognition in vivo[116].

    Both astaxanthin and lycopene exhibit promising roles in geroprotective strategies, particularly in enhancing NAD+ levels and SIRT1 activation. Their combined use with NMN or other NAD+ precursors could potentially maximize the efficacy of interventions aimed at boosting NAD+ availability and combating age-related decline.

    Curcumin[edit | edit source]

    Curcumin, a compound derived from turmeric, is gaining recognition as a potent senolytic agent, similar to the flavonoids previously discussed (Figure 2). Its effects on aging and age-related pathologies are significant and multifaceted:

    • Senescence and Longevity Pathways: Curcumin has shown promising results in improving cellular senescence associated with aging. It also modulates key longevity pathways, such as mTOR and FoxO, indicating its potential in extending healthy lifespan[117].
    • Neurodegenerative Diseases: In the realm of neurodegeneration, curcumin has been found to upregulate SIRT1, a protein linked to aging and cellular health[118]. This effect suggests its potential in mitigating neurodegenerative disorders.
    • Cardiovascular Health: Curcumin's impact on cardiovascular health is highlighted by its ability to activate AMPK, another significant pathway in aging and metabolic regulation[118].
    • Anti-cancer Properties: Experimental models of head and neck squamous cell carcinoma have shown that curcumin can inhibit cancer cell migration and angiogenesis, underscoring its anti-cancer potential[119].
    • Physical Performance: A six-week supplementation with curcumin in human runners has led to improvements in antioxidant capacity and aerobic performance. This benefit is accompanied by an increase in SIRT3, a mitochondrial protein linked to energy metabolism[120].

    The relationship between curcumin and sirtuins, particularly in the context of NAD+ boosting, is a promising area of research. However, the effectiveness of combining curcumin with NAD+ enhancing supplements needs to be explored further in clinical trials. Such studies would help establish whether curcumin can augment the benefits of NAD+ precursors, potentially leading to more effective anti-aging therapies.

    Alpha-Ketoglutarate[edit | edit source]

    Alpha-ketoglutarate (aKG) is a critical metabolic intermediate in the Krebs cycle, playing an important role in the aging process[121]. Its involvement in various longevity-related mechanisms makes it a significant compound in geroprotection and anti-aging research.

    • Inhibition of the TOR Pathway: aKG is known to inhibit the TOR pathway, akin to the effects of caloric restriction. This inhibition, coupled with its ability to hinder ATP synthase, has been shown to extend the lifespan in C. elegans[122].
    • Metabolic and Antioxidant Benefits: Providing both metabolic and antioxidant benefits, aKG has been demonstrated to extend lifespan. This effect is evident not only in model organisms but also in mice. Recent pilot clinical trials have indicated that Rejuvant, a novel formulation of aKG, effectively reduces biological age in humans[123][124][125].
    • Interplay with NAD+: The relationship between aKG and NAD+, a vital coenzyme for cellular health and aging, remains under-researched. Future studies should explore this interaction to enhance our understanding of how aKG can be utilized in longevity therapies.

    The potential of aKG in anti-aging strategies is promising, but more research is necessary to fully understand its interactions, particularly with NAD+.

    Epigallocatechin Gallate[edit | edit source]

    The polyphenol epigallocatechin gallate (EGCG; Figure 2), predominantly found in green tea, is renowned for its neuroprotective, antioxidant, and anti-inflammatory properties. Current research is investigating its role in alleviating a variety of diseases[126]. EGCG's interaction with aging and longevity pathways is particularly noteworthy.

    • Lifespan Extension: EGCG has been shown to increase lifespan in response to oxidative stress, as evidenced by studies in rats demonstrating enhanced longevity under such conditions[127].
    • SIRT1 Modulation: The effect of EGCG on SIRT1, a crucial protein in aging and metabolism, appears to vary depending on the context. Some studies have observed an upregulation of SIRT1 following EGCG administration[128], while others have reported a downregulation, especially in cancer cells[129][130]. This suggests that EGCG's impact on SIRT1 may differ based on specific biological factors and the need for upregulation of longevity pathways in response to oxidative stress.
    • NAD+/NADH Ratio Effects: The influence of EGCG on the NAD+/NADH ratio, vital for cellular metabolism and aging, requires further investigation. Understanding how EGCG affects this ratio is essential for comprehending its potential as an anti-aging agent and its role in cellular health maintenance.

    The diverse effects of EGCG on SIRT1 and the NAD+/NADH ratio underline the importance of more detailed research to clarify its mechanisms of action, particularly regarding longevity and age-related diseases.

    Clinical Trials[edit | edit source]

    Starting in 2020, with the assessment of the safety of a single dose administration of NMN, there have been around 10 randomized controlled trials (RCTs) exploring the compound's effects in various contexts. The trials have varied in duration, with the longest running for 12 weeks. In terms of dosage, they have explored a range of quantities, with the highest being 1,250 mg of NMN per day and 2,000 mg (2 g) of MIB-626, a specific formulation of NMN, per day. The following table provides a comprehensive overview of these trials, detailing their design, participant demographics, dosages, and key findings:

    Clinical Trials of NMN
    Clinical Trial Design

    (dosage is per day, 2x means twice per day)

    Participants Outcome
    2020, Effect of oral administration of nicotinamide mononucleotide on clinical parameters and nicotinamide metabolite levels in healthy Japanese men [131] singe admission
    • up to 500 mg
    • 10 healthy men
    • age 40-60
    • admission was safe and well-tolerated
    2021, Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women [1] RCT, 10 weeks
    • placebo (n=12)
    • 250 mg (n=13)
    • 25 postmenopausal women with prediabetes
    • overweight or obese (BMI 25.3 - 39.1)
    • age 56-66
    • increase in skeletal muscle insulin signaling, insulin sensitivity, and muscle remodeling
    • improvement in muscle insulin sensitivity is clinically relevant and is similar to the improvement observed after ~10% weight loss
    2021, Nicotinamide mononucleotide supplementation enhances aerobic capacity in amateur runners: a randomized, double-blind study [44] RCT, 6 weeks
    • placebo (n=12)
    • 300 mg (n=12)
    • 600 mg (n=12)
    • 1200 mg (n=12)
    • 48 young and middle-aged recreationally trained runners
    • age 35 average
    • The combination of NMN supplementation and exercise further improves ventilatory threshold even among healthy young and middle-aged people.
    • The improvement of aerobic capacity is in a dosage-dependent, large dosage of NMN with exercise has better effects.
    • The improvement is muscle, not cardiac, related.
    2021, The Impacts of Short-Term NMN Supplementation on Serum Metabolism, Fecal Microbiota, and Telomere Length in Pre-Aging Phase [45] 90 days
    • 300 mg in warm water
    • 8 healthy men
    • age 45–60
    *
    • NMN doubles the telomere length of humans over a 90-day period of time.
    2022, Safety evaluation of β-nicotinamide mononucleotide oral administration in healthy adult men and women [132] RCT, 4 weeks
    • placebo (n=15)
    • 1250 mg (n=16)
    • 31 healthy adult men and women
    • age 20–65
    • Oral administration of 1250 mg of NMN, when administered once daily for up to 4 weeks, was safe and well-tolerated in healthy adult men and women.
    • Oral administration of NMN in humans has a low adverse effect on renal function.
    • Results indicate that NMN can be administered orally to humans at doses 1250 mg once daily for up to 4 weeks without causing hepatotoxicity and vasodilative flushing, and is believed to have a higher upper tolerable limit compared to NAM and NA.
    2022, Effect of 12-Week Intake of Nicotinamide Mononucleotide on Sleep Quality, Fatigue, and Physical Performance in Older Japanese Adults: A Randomized, Double-Blind Placebo-Controlled Study [43] RCT, 12 weeks
    • placebo, before 12 pm
    • placebo, after 6 pm
    • 250 mg, before 12 pm
    • 250 mg, after 6 pm
    • 108 older adults
    • age ≥ 65
    • NMN intake in the afternoon is more effective in improving lower limb function and reducing drowsiness in older adults.
    2022, Chronic nicotinamide mononucleotide supplementation elevates blood nicotinamide adenine dinucleotide levels and alters muscle function in healthy older men [8] RCT, 12 weeks
    • placebo (n=10)
    • 250 mg (n=10)
    • 20 healthy male
    • age ≥ 65
    • BMI 22–28
    • nonsmokers
    • 250 mg of NMN per day for 12 weeks significantly increased NAD+ blood levels in healthy males older than 65.
    • The supplementation regimen improves walking speed and grip strength in the aged men.
    • These findings suggest NMN supplementation may be used to ameliorate age-related muscle deterioration.
    2022, A Multicentre, Randomised, Double Blind, Parallel Design, Placebo Controlled Study to Evaluate the Efficacy and Safety of Uthever (NMN Supplement), an Orally Administered Supplementation in Middle Aged and Older Adults [7] RCT, 60 days
    • placebo (n=31)
    • 300 mg (n=31)
    • 66 healthy subjects
    • age 40-65
    • NAD+/NADH concentration in serum increase by 11.3% after 30 days, 38% after 60 days
    2022, Nicotinamide Mononucleotide Is Safely Metabolized and Significantly Reduces Blood Triglyceride Levels in Healthy Individuals [133] single intravenous administration
    • 300 mg
    • 10 healthy adults
    • age 20-70
    • 300 mg intravenous NMN administration is tolerated by humans
    • significantly increased blood NAD+ levels
    2023, The efficacy and safety of β-nicotinamide mononucleotide (NMN) supplementation in healthy middle-aged adults: a randomized, multicenter, double-blind, placebo-controlled, parallel-group, dose-dependent clinical trial [134] RCT, 8.5 weeks (60 days)
    • placebo (n=20)
    • 300 mg (n=20)
    • 600 mg (n=20)
    • 900 mg (n=20)
    • healthy males and females
    • age 40-65
    • BMI between 18.5 and 35
    • Oral administration of NMN up to 900 mg/day for 60 days was safe and well tolerated
    • blood NAD concentration was significantly and dose-dependently increased
    • significant improvement of six-minute walking test, blood biological age, and SF-36 scores
    • 900 mg/day oral dose did not give significantly better efficacy than 600 mg/day dose
    2023, MIB-626, an Oral Formulation of a Microcrystalline Unique Polymorph of β-Nicotinamide Mononucleotide, Increases Circulating Nicotinamide Adenine Dinucleotide and its Metabolome in Middle-Aged and Older Adults [3] RCT, 2 weeks
    • 1000 mg MIB-626
    • 2x1000 mg MIB-626
    • placebo
    • 32 overweight or obese adults
    • age 55-80
    • MIB-626 was well tolerated
    • Blood NMN concentrations significantly higher in treated groups compared to placebo
    • Substantial dose-related increases in blood NAD levels and its metabolome
    • Changes in NMN or NAD levels not related to sex, BMI, or age
    • Very little unmodified NMN excreted in urine
    • Facilitates design of efficacy trials in disease conditions
    2023, Nicotinamide Adenine Dinucleotide Augmentation in Overweight or Obese Middle-Aged and Older Adults: A Physiologic Study [51] RCT, 4 weeks
    • 2x500 mg/day MIB-626
    • placebo
    • 30 overweight or obese adults
    • age ≥ 45
    • MIB-626 treatment increased circulating NAD and metabolites
    • No significant change in muscle strength, muscle fatigability, aerobic capacity, and stair-climbing power
    • Significant reduction in body weight, diastolic blood pressure, total LDL, and non-HDL cholesterol
    • Insulin sensitivity and hepatic and intra-abdominal fat unchanged
    • Adverse events similar between groups
    • Provides rationale for larger trials on NAD augmentation for cardiometabolic outcomes in older adults
    2023, Nicotinamide adenine dinucleotide metabolism and arterial stiffness after long-term nicotinamide mononucleotide supplementation: a randomized, double-blind, placebo-controlled trial [135] RCT, 12 weeks, capsules
    • placebo (n=17)
    • 2x125 mg (n=17)
    • 34 healthy male and female
    • age 40-59
    • 250 mg of NMN for 12 weeks does not significantly reduce artery stiffness — a risk factor for cardiovascular disease, dementia, and death — in healthy middle-aged adults.
    • However, NMN reduces artery stiffness in individuals with high blood-glucose and body mass index (weight/height).
    • Blood vessel biological aging is reversed by 2 years with NMN treatment.
    2023, Effects of nicotinamide mononucleotide on older patients with diabetes and impaired physical performance: A prospective, placebo-controlled, double-blind study [136] RCT, 24-week
    • placebo
    • 250 mg
    • male patients with diabetes
    • reduced grip strength (<26 kg) or walking speed (<1.0 m/s)
    • age ≥ 65
    • NMN was tolerable without any severe adverse events
    • NMN did not improve grip strength and walking speed
    • Improved prevalence of frailty in the NMN group (P = 0.066)
    • Different changes in central retinal thickness between the two groups (P = 0.051)
    2023, NAD+ exhaustion by CD38 upregulation contributes to blood pressure elevation and vascular damage in hypertension [6] 6 weeks, lifestyle modifications
    • no NMN (n=10)
    • 800 mg (n=9)
    • 19 mild hypertensive adults
    • age 18-80
    • Supplementing hypertension patients with 800 mg of oral NMN per day for six weeks significantly lowers their blood pressure.
    • Hypertension patients display significantly lower blood cell NAD+ levels, and taking NMN increases their blood cell NAD+ levels by ~43%.
    • Adults with hypertension have cells lining blood vessels — endothelial cells — with elevated concentrations of the NAD+ consuming enzyme CD38, which partially explains their lower NAD+ levels.
    2022, Oral Administration of Nicotinamide Mononucleotide Is Safe and Efficiently Increases Blood Nicotinamide Adenine Dinucleotide Levels in Healthy Subjects [5]
    2023, Nicotinamide mononucleotide (NMN) intake increases plasma NMN and insulin levels in healthy subjects [9]

    See also[edit | edit source]

    Todo[edit | edit source]

    2022, Nicotinamide Mononucleotide Supplementation Improves Mitochondrial Dysfunction and Rescues Cellular Senescence by NAD+/Sirt3 Pathway in Mesenchymal Stem Cells [140]

    References[edit | edit source]

    1. 1.0 1.1 1.2 Yoshino M et al.: Nicotinamide mononucleotide increases muscle insulin sensitivity in prediabetic women. Science 2021. (PMID 33888596) [PubMed] [DOI] [Full text] In rodents, obesity and aging impair nicotinamide adenine dinucleotide (NAD+) biosynthesis, which contributes to metabolic dysfunction. Nicotinamide mononucleotide (NMN) availability is a rate-limiting factor in mammalian NAD+ biosynthesis. We conducted a 10-week, randomized, placebo-controlled, double-blind trial to evaluate the effect of NMN supplementation on metabolic function in postmenopausal women with prediabetes who were overweight or obese. Insulin-stimulated glucose disposal, assessed by using the hyperinsulinemic-euglycemic clamp, and skeletal muscle insulin signaling [phosphorylation of protein kinase AKT and mechanistic target of rapamycin (mTOR)] increased after NMN supplementation but did not change after placebo treatment. NMN supplementation up-regulated the expression of platelet-derived growth factor receptor β and other genes related to muscle remodeling. These results demonstrate that NMN increases muscle insulin sensitivity, insulin signaling, and remodeling in women with prediabetes who are overweight or obese (clinicaltrial.gov NCT03151239).
    2. https://www.nmn.com/news/fda-bans-labeling-nmn-as-a-supplement
    3. 3.0 3.1 3.2 3.3 Pencina KM et al.: MIB-626, an Oral Formulation of a Microcrystalline Unique Polymorph of β-Nicotinamide Mononucleotide, Increases Circulating Nicotinamide Adenine Dinucleotide and its Metabolome in Middle-Aged and Older Adults. J Gerontol A Biol Sci Med Sci 2023. (PMID 35182418) [PubMed] [DOI] BACKGROUND: Nicotinamide adenine dinucleotide (NAD) precursors, nicotinamide mononucleotide (NMN), or nicotinamide riboside (NR) extend healthspan and ameliorate some age-related conditions in model organisms. However, early-phase trials of NAD precursors have yielded varying results and their pharmacokinetics remain incompletely understood. Here, we report the pharmacokinetics and pharmacodynamics of MIB-626, a microcrystalline unique polymorph βNMN formulation. METHODS: In this double-blind, placebo-controlled study, 32 overweight or obese adults, 55-80 years, were block-randomized, stratified by sex, to 1 000-mg MIB-626 once daily, twice daily, or placebo for 14 days. NMN, NAD, and NAD metabolome were measured using liquid chromatography-tandem mass spectrometry. RESULTS: Participant characteristics were similar across groups. MIB-626 was well tolerated and frequency of adverse events was similar across groups. Blood NMN concentrations on Day 14 in MIB-626-treated groups were significantly higher compared to placebo (1.7-times and 3.7-times increase above baseline in 1 000 mg once-daily and twice-daily groups in mean AUClast, respectively). MIB-626 treatment was associated with substantial dose-related increases in blood NAD levels. Blood levels of NAD metabolites were higher in NMN-treated participants on Days 8 and 14 than at baseline. Changes in NMN or NAD levels were not related to sex, body mass index, or age. Very little unmodified NMN was excreted in the urine. CONCLUSION: MIB-626 1 000 mg once-daily or twice-daily regimens were safe and associated with substantial dose-related increases in blood NAD levels and its metabolome. These foundational data that were obtained using a pharmaceutical-grade βNMN, standardized sample collection, and validated liquid chromatography-tandem mass spectrometry assays, should facilitate design of efficacy trials in disease conditions.
    4. 4.0 4.1 Zhang D et al.: Hydroxyapatite-based nano-drug delivery system for nicotinamide mononucleotide (NMN): significantly enhancing NMN bioavailability and replenishing in vivo nicotinamide adenine dinucleotide (NAD+) levels. J Pharm Pharmacol 2023. (PMID 37862582) [PubMed] [DOI] OBJECTIVES: This study addresses the bioavailability challenges associated with oral nicotinamide mononucleotide (NMN) administration by introducing an innovative NMN formulation incorporated with hydroxyapatite (NMN-HAP). METHODS: The NMN-HAP was developed using a wet chemical precipitation and physical adsorption method. To assess its superiority over conventional free NMN, we examined NMN, nicotinamide adenine dinucleotide (NAD+), and nicotinamide riboside (NR) levels in mouse plasma and tissues following oral administration of NMN-HAP. KEY FINDINGS: NMN-HAP nanoparticles demonstrated a rod-shaped morphology, with an average size of ~50 nm, along with encapsulation efficiency and drug loading capacity exceeding 40%. In vitro, drug release results indicated that NMN-HAP exhibited significantly lower release compared with free NMN. In vivo studies showed that NMN-HAP extended circulation time, improved bioavailability compared with free NMN, and elevated plasma levels of NMN, NAD+, and NR. Moreover, NMN-HAP administration displayed tissue-specific distribution with a substantial accumulation of NMN, NAD+, and NR in the brain and liver. CONCLUSION: NMN-HAP represents an ideal formulation for enhancing NMN bioavailability, enabling tissue-specific delivery, and ultimately elevating in vivo NAD+ levels. Considering HAP's biocompatible nature and versatile characteristics, we anticipate that this system has significant potential for various future applications.
    5. 5.0 5.1 5.2 5.3 Okabe K et al.: Oral Administration of Nicotinamide Mononucleotide Is Safe and Efficiently Increases Blood Nicotinamide Adenine Dinucleotide Levels in Healthy Subjects. Front Nutr 2022. (PMID 35479740) [PubMed] [DOI] [Full text] Nicotinamide mononucleotide (NNM) is an orally bioavailable NAD+ precursor that has demonstrated beneficial effects against aging and aging-associated diseases in animal models. NMN is ultimately converted to NAD+, a redox cofactor that mediates many metabolic enzymes. NAD+ also serves as the substrate for poly(ADP-ribose) polymerase (PARP) and sirtuins, and regulates various biological processes, such as metabolism, DNA repair, gene expression, and stress responses. Previous mouse models showed that NMN administration can increase NAD+ in various organs and ameliorate aging-related diseases, such as obesity, diabetes, heart failure, stroke, kidney failure, and Alzheimer's disease through NAD+-mediated pathways. However, evidence of its effect on humans is still scarce. In this study, we conducted a placebo-controlled, randomized, double blind, parallel-group trial to investigate the safety of orally administered NMN and its efficacy to increase NAD+ levels in thirty healthy subjects. Healthy volunteers received 250 mg/day of NMN (n = 15) or placebo (n = 15) for 12 weeks, and physiological and laboratory tests were performed during this period. In addition, NAD+ and its related metabolites in whole blood were examined. Oral supplementation of NMN for 12 weeks caused no abnormalities in physiological and laboratory tests, and no obvious adverse effects were observed. NAD+ levels in whole blood were significantly increased after NMN administration. We also observed the significant rise in nicotinic acid mononucleotide (NAMN) levels, but not in NMN. We also found that the increased amount of NAD+ was strongly correlated with pulse rate before the administration of NMN. These results suggest that oral administration of NMN is a safe and practical strategy to boost NAD+ levels in humans. Clinical Trial Registration: JRCT [1], identifier: [jRCTs041200034].
    6. 6.0 6.1 6.2 6.3 Qiu Y et al.: NAD+ exhaustion by CD38 upregulation contributes to blood pressure elevation and vascular damage in hypertension. Signal Transduct Target Ther 2023. (PMID 37718359) [PubMed] [DOI] [Full text] Hypertension is characterized by endothelial dysfunction and arterial stiffness, which contribute to the pathogenesis of atherosclerotic cardiovascular diseases. Nicotinamide adenine dinucleotide (NAD+) is an indispensable cofactor in all living cells that is involved in fundamental biological processes. However, in hypertensive patients, alterations in NAD+ levels and their relation with blood pressure (BP) elevation and vascular damage have not yet been studied. Here we reported that hypertensive patients exhibited lower NAD+ levels, as detected by high-performance liquid chromatography-mass spectrometry (HPLC-MS), in both peripheral blood mononuclear cells (PBMCs) and aortas, which was parallel to vascular dysfunction. NAD+ boosting therapy with nicotinamide mononucleotide (NMN) supplement reduced BP and ameliorated vascular dysfunction in hypertensive patients (NCT04903210) and AngII-induced hypertensive mice. Upregulation of CD38 in endothelial cells led to endothelial NAD+ exhaustion by reducing NMN bioavailability. Pro-inflammatory macrophages infiltration and increase in IL-1β generation derived from pro-inflammatory macrophages resulted in higher CD38 expression by activating JAK1-STAT1 signaling pathway. CD38 KO, CD38 inhibitors treatment, or adeno-associated virus (AAV)-mediated endothelial CD38 knockdown lowered BP and improved vascular dysfunction in AngII-induced hypertensive mice. The present study demonstrated for the first time that endothelial CD38 activation and subsequently accelerated NAD+ degradation due to enhanced macrophage-derived IL-1β production was responsible for BP elevation and vascular damage in hypertension. NAD+ boosting therapy can be used as a novel therapeutic strategy for the management of hypertensive patients.
    7. 7.0 7.1 7.2 Huang H: A Multicentre, Randomised, Double Blind, Parallel Design, Placebo Controlled Study to Evaluate the Efficacy and Safety of Uthever (NMN Supplement), an Orally Administered Supplementation in Middle Aged and Older Adults. Front Aging 2022. (PMID 35821806) [PubMed] [DOI] [Full text] Objective: The purpose of the study was to evaluate the anti-aging effect of NMN and its safety in a double-blind, parallel, randomised controlled clinical trial. Methods: The study was carried out on 66 healthy subjects between the ages of 40 and65 years, instructed to take two capsules (each containing 150 mg. of NMN or starch powder) once a day after breakfast for 60 days. Results: At day 30, NAD+/NADH levels in the serum showed a noteworthy increase, i.e., by 11.3%, whereas the placebo group had shown no change at all. At the end of the study, i.e., day 60, the NAD+/NADH levels were increased further by 38% compared to baseline, against a mere 14.3% in the placebo group. In the case of SF 36, at day 60, the Uthever group showed a rise of 6.5%, whereas the placebo group was merely raised by 3.4%. At the end of the study, the mean HOMA IR Index showed a rise of 0.6% among the Uthever group and 30.6% among the Placebo group from baseline. Conclusion: The rise in the levels of NAD+/NADH at day 30 and day 60 illustrated the potential of Uthever to raise the levels of NAD+ in the cells, which is linked to higher energy levels and an anti-aging effect. Increased sensitivity to insulin has also been linked to anti-aging. There was no noteworthy change in HOMA score, in the Uthever group whereas there was a noteworthy rise in the placebo group, demonstrating the anti-aging effect of Uthever as in its absence, the parameters worsened. Clinical Trial Registration: (clinicaltrials.gov), identifier (NCT04228640 NMN).
    8. 8.0 8.1 8.2 8.3 8.4 Igarashi M et al.: Chronic nicotinamide mononucleotide supplementation elevates blood nicotinamide adenine dinucleotide levels and alters muscle function in healthy older men. NPJ Aging 2022. (PMID 35927255) [PubMed] [DOI] [Full text] Preclinical studies have revealed that the elevation of nicotinamide adenine dinucleotide (NAD + ) upon the administration of nicotinamide mononucleotide (NMN), an NAD + precursor, can mitigate aging-related disorders; however, human data on this are limited. We investigated whether the chronic oral supplementation of NMN can elevate blood NAD + levels and alter physiological dysfunctions in healthy older participants. We administered 250 mg NMN per day to aged men for 6 or 12 weeks in a placebo-controlled, randomized, double-blind, parallel-group trial. Chronic NMN supplementation was well tolerated and caused no significant deleterious effect. Metabolomic analysis of whole blood samples demonstrated that oral NMN supplementation significantly increased the NAD + and NAD + metabolite concentrations. There were nominally significant improvements in gait speed and performance in the left grip test, which should be validated in larger studies; however, NMN exerted no significant effect on body composition. Therefore, chronic oral NMN supplementation can be an efficient NAD + booster for preventing aging-related muscle dysfunctions in humans.
    9. 9.0 9.1 9.2 Yamane T et al.: Nicotinamide mononucleotide (NMN) intake increases plasma NMN and insulin levels in healthy subjects. Clin Nutr ESPEN 2023. (PMID 37344088) [PubMed] [DOI] INTRODUCTION: Nicotinamide adenine dinucleotide (NAD+) is a coenzyme of the NAD+-dependent protein deacetylase sirtuin-1 (SIRT1). An increase in NAD+ concentration induces SIRT1 activation that results in various health benefits. Since nicotinamide mononucleotide (NMN) is a precursor of NAD+, NMN ingestion is expected to have multiple health benefits such as alleviation of aging, lifestyle-related and neurodegenerative diseases, through the activation of SIRT1. In this study, we aimed to determine the effects of daily NMN ingestion on plasma levels of NMN and NAD+. METHODS: Healthy volunteers received 250 mg of NMN once a day in the morning (n = 11) for 12 weeks, and the plasma concentrations of NMN and NAD+ were measured monthly. Physiological and laboratory tests were performed within 2 h after lunch (at 2 pm) before and during NMN administration. RESULTS: Oral administration of NMN increased the plasma concentrations of NMN and NAD+, and the postprandial serum insulin levels. The elevation levels of NMN and insulin varied widely among individuals. No adverse symptoms were observed in the participants. CONCLUSIONS: Oral administration of NMN elevates plasma levels of NMN and NAD+, and postprandial serum insulin levels.
    10. 10.0 10.1 Bai LB et al.: Improvement of tissue-specific distribution and biotransformation potential of nicotinamide mononucleotide in combination with ginsenosides or resveratrol. Pharmacol Res Perspect 2022. (PMID 35844164) [PubMed] [DOI] [Full text] Decreased Nicotinamide adenine dinucleotide (NAD+ ) level has received increasing attention in recent years since it plays a critical role in many diseases and aging. Although some research has proved that supplementing nicotinamide mononucleotide (NMN) could improve the level of NAD+ , it is still uncertain whether the NAD+ level in specific tissues could be improved in combination with other nutrients. So far, a variety of nutritional supplements have flooded the market, which contains the compositions of NMN coupled with natural products. However, the synergy and transformation process of NMN has not been fully elucidated. In this study, oral administration of NMN (500 mg/kg) combined with resveratrol (50 mg/kg) or ginsenoside Rh2&Rg3 (50 mg/kg) was used to validate the efficacy of appropriate drug combinations in mice. Compared with NMN alone, NMN combined with resveratrol could increase the levels of NAD+ in the heart and muscle by about 1.6 times and 1.7 times, respectively, whereas NMN coupled with ginsenoside Rh2&Rg3 could effectively improve the level of NAD+ in lung tissue for approximately 2.0 times. Our study may provide new treatment ideas for aging or diseases in cardiopulmonary caused by decreased NAD+ levels.
    11. Grozio A et al.: Slc12a8 is a nicotinamide mononucleotide transporter. Nat Metab 2019. (PMID 31131364) [PubMed] [DOI] [Full text] Nicotinamide mononucleotide (NMN) is a biosynthetic precursor of NAD+ known to promote cellular NAD+ production and counteract age-associated pathologies associated with a decline in tissue NAD+ levels. How NMN is taken up into cells has not been entirely clear. Here we show that the Slc12a8 gene encodes a specific NMN transporter. We find that Slc12a8 is highly expressed and regulated by NAD+ in the murine small intestine. Slc12a8 knockdown abrogates the uptake of NMN in vitro and in vivo. We further show that Slc12a8 specifically transports NMN, but not nicotinamide riboside, and that NMN transport depends on the presence of sodium ion. Slc12a8 deficiency significantly decreases NAD+ levels in the jejunum and ileum, which is associated with reduced NMN uptake as traced by doubly labeled isotopic NMN. Finally, we observe that Slc12a8 expression is upregulated in the aged murine ileum, which contributes to the maintenance of ileal NAD+ levels. Our work identifies the first NMN transporter and demonstrates that Slc12a8 has a critical role in regulating intestinal NAD+ metabolism.
    12. Schmidt MS & Brenner C: Absence of evidence that Slc12a8 encodes a nicotinamide mononucleotide transporter. Nat Metab 2019. (PMID 32694648) [PubMed] [DOI]
    13. 13.0 13.1 Ratajczak J et al.: NRK1 controls nicotinamide mononucleotide and nicotinamide riboside metabolism in mammalian cells. Nat Commun 2016. (PMID 27725675) [PubMed] [DOI] [Full text] NAD+ is a vital redox cofactor and a substrate required for activity of various enzyme families, including sirtuins and poly(ADP-ribose) polymerases. Supplementation with NAD+ precursors, such as nicotinamide mononucleotide (NMN) or nicotinamide riboside (NR), protects against metabolic disease, neurodegenerative disorders and age-related physiological decline in mammals. Here we show that nicotinamide riboside kinase 1 (NRK1) is necessary and rate-limiting for the use of exogenous NR and NMN for NAD+ synthesis. Using genetic gain- and loss-of-function models, we further demonstrate that the role of NRK1 in driving NAD+ synthesis from other NAD+ precursors, such as nicotinamide or nicotinic acid, is dispensable. Using stable isotope-labelled compounds, we confirm NMN is metabolized extracellularly to NR that is then taken up by the cell and converted into NAD+. Our results indicate that mammalian cells require conversion of extracellular NMN to NR for cellular uptake and NAD+ synthesis, explaining the overlapping metabolic effects observed with the two compounds.
    14. Mateuszuk Ł et al.: Reversal of endothelial dysfunction by nicotinamide mononucleotide via extracellular conversion to nicotinamide riboside. Biochem Pharmacol 2020. (PMID 32389638) [PubMed] [DOI] BACKGROUND: Nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR) are effective substrates for NAD synthesis, which may act as vasoprotective agents. Here, we characterize the effects of NMN and NR on endothelial inflammation and dysfunction and test the involvement of CD73 in these effects. MATERIALS AND METHODS: The effect of NMN and NR on IL1β- or TNFα-induced endothelial inflammation (ICAM1 and vWF expression), intracellular NAD concentration and NAD-related enzyme expression (NAMPT, CD38, CD73), were studied in HAECs. The effect of NMN and NR on angiotensin II-induced impairment of endothelium-dependent vasodilation was analyzed in murine aortic rings. The involvement of CD73 in NMN and NR effects was tested using CD73 inhibitor-AOPCP, or CD73-/- mice. RESULTS: 24 h-incubation with NMN and NR induced anti-inflammatory effects in HAEC stimulated by IL1β or TNFα, as evidenced by a reduction in ICAM1 and vWF expression. Effects of exogenous NMN but not NR was abrogated in the presence of AOPCP, that efficiently inhibited extracellular endothelial conversion of NMN to NR, without a significant effect on the metabolism of NMN to NA. Surprisingly, intracellular NAD concentration increased in HAEC stimulated by IL1β or TNFα and this effect was associated with upregulation of NAMPT and CD73, whereas changes in CD38 expression were less pronounced. NMN and NR further increased NAD in IL1β-stimulated HAECs and AOPCP diminished NMN-induced increase in NAD, without an effect on NR-induced response. In ex vivo aortic rings stimulated with angiotensin II for 24 h, NO-dependent vasorelaxation induced by acetylcholine was impaired. NMN and NR, both prevented Ang II-induced endothelial dysfunction in the aorta. In aortic rings taken from CD73-/- mice NMN effect was lost, whereas NR effect was preserved. CONCLUSION: NMN and NR modulate intracellular NAD content in endothelium, inhibit endothelial inflammation and improve NO-dependent function by CD73-dependent and independent pathways, respectively. Extracellular conversion of NMN to NR by CD73 localized in the luminal surface of endothelial cells represent important vasoprotective mechanisms to maintain intracellular NAD.
    15. Kim LJ et al.: Host-microbiome interactions in nicotinamide mononucleotide (NMN) deamidation. FEBS Lett 2023. (PMID 37463842) [PubMed] [DOI] The nicotinamide adenine dinucleotide (NAD+ ) precursor nicotinamide mononucleotide (NMN) is a proposed therapy for age-related disease, whereby it is assumed that NMN is incorporated into NAD+ through the canonical recycling pathway. During oral delivery, NMN is exposed to the gut microbiome, which could modify the NAD+ metabolome through enzyme activities not present in the mammalian host. We show that orally delivered NMN can undergo deamidation and incorporation in mammalian tissue via the de novo pathway, which is reduced in animals treated with antibiotics to ablate the gut microbiome. Antibiotics increased the availability of NAD+ metabolites, suggesting the microbiome could be in competition with the host for dietary NAD+ precursors. These findings highlight new interactions between NMN and the gut microbiome.
    16. Song Q et al.: The Safety and Antiaging Effects of Nicotinamide Mononucleotide in Human Clinical Trials: an Update. Adv Nutr 2023. (PMID 37619764) [PubMed] [DOI] The importance of nicotinamide adenine dinucleotide (NAD+) in human physiology is well recognized. As the NAD+ concentration in human skin, blood, liver, muscle, and brain are thought to decrease with age, finding ways to increase NAD+ status could possibly influence the aging process and associated metabolic sequelae. Nicotinamide mononucleotide (NMN) is a precursor for NAD+ biosynthesis, and in vitro/in vivo studies have demonstrated that NMN supplementation increases NAD+ concentration and could mitigate aging-related disorders such as oxidative stress, DNA damage, neurodegeneration, and inflammatory responses. The promotion of NMN as an antiaging health supplement has gained popularity due to such findings; however, since most studies evaluating the effects of NMN have been conducted in cell or animal models, a concern remains regarding the safety and physiological effects of NMN supplementation in the human population. Nonetheless, a dozen human clinical trials with NMN supplementation are currently underway. This review summarizes the current progress of these trials and NMN/NAD+ biology to clarify the potential effects of NMN supplementation and to shed light on future study directions.
    17. Wang X et al.: Nicotinamide mononucleotide protects against β-amyloid oligomer-induced cognitive impairment and neuronal death. Brain Res 2016. (PMID 27130898) [PubMed] [DOI] Amyloid-β (Aβ) oligomers are recognized as the primary neurotoxic agents in Alzheimer's disease (AD). Impaired brain energy metabolism and oxidative stress are implicated in cognitive decline in AD. Nicotinamide adenine dinucleotide (NAD(+)), a coenzyme involved in redox activities in the mitochondrial electron transport chain, has been identified as a key regulator of the lifespan-extending effects, and the activation of NAD(+) expression has been linked with a decrease in Aβ toxicity in AD. One of the key precursors of NAD(+) is nicotinamide mononucleotide (NMN), a product of the nicotinamide phosphoribosyltransferase reaction. To determine whether improving brain energy metabolism will forestall disease progress in AD, the impact of the NAD(+) precursor NMN on Aβ oligomer-induced neuronal death and cognitive impairment were studied in organotypic hippocampal slice cultures (OHCs) and in a rat model of AD. Treatment of intracerebroventricular Aβ oligomer infusion AD model rats with NMN (500mg/kg, intraperitoneally) sustained improvement in cognitive function as assessed by the Morris water maze. In OHCs, Aβ oligomer-treated culture media with NMN attenuated neuronal cell death. NMN treatment also significantly prevented the Aβ oligomer-induced inhibition of LTP. Furthermore, NMN restored levels of NAD(+) and ATP, eliminated accumulation of reactive oxygen species (ROS) in the Aβ oligomer-treated hippocampal slices. All these protective effects were reversed by 3-acetylpyridine, which generates inactive NAD(+). The present study indicates that NMN could restore cognition in AD model rats. The beneficial effect of NMN is produced by ameliorating neuron survival, improving energy metabolism and reducing ROS accumulation. These results suggest that NMN may become a promising therapeutic drug for AD.
    18. Ramanathan C et al.: Oral Administration of Nicotinamide Mononucleotide Increases Nicotinamide Adenine Dinucleotide Level in an Animal Brain. Nutrients 2022. (PMID 35057482) [PubMed] [DOI] [Full text] As a redox-sensitive coenzyme, nicotinamide adenine dinucleotide (NAD+) plays a central role in cellular energy metabolism and homeostasis. Low NAD+ levels are linked to multiple disease states, including age-related diseases, such as metabolic and neurodegenerative diseases. Consequently, restoring/increasing NAD+ levels in vivo has emerged as an important intervention targeting age-related neurodegenerative diseases. One of the widely studied approaches to increase NAD+ levels in vivo is accomplished by using NAD+ precursors, such as nicotinamide mononucleotide (NMN). Oral administration of NMN has been shown to successfully increase NAD+ levels in a variety of tissues; however, it remains unclear whether NMN can cross the blood-brain barrier to increase brain NAD+ levels. This study evaluated the effects of oral NMN administration on NAD+ levels in C57/B6J mice brain tissues. Our results demonstrate that oral gavage of 400 mg/kg NMN successfully increases brain NAD+ levels in mice after 45 min. These findings provide evidence that NMN may be used as an intervention to increase NAD+ levels in the brain.
    19. Zheng SL et al.: Distribution of Nicotinamide Mononucleotide after Intravenous Injection in Normal and Ischemic Stroke Mice. Curr Pharm Biotechnol 2023. (PMID 35593333) [PubMed] [DOI] OBJECTIVE: This study determined for the first time the distribution of intravenous nicotinamide mononucleotide (NMN) and its metabolite nicotinamide adenine dinucleotide (NAD) in normal and ischemic stroke mice, examined the therapeutic effect of NMN on ischemic brain infarction, and evaluated acute toxicity of NMN after intravenous injection of NMN. METHODS: NMN and NAD levels were determined using ultra-high-performance liquid chromatography tandem mass spectrometry in biological samples from mice with or without middle cerebral artery occlusion (MCAO) at different time points post intravenous NMN injection (300 mg/kg). Brain infarction was evaluated 24 h post-MCAO. 2 g/kg NMN was used in the acute toxicity test. RESULTS: Under either normal or MCAO conditions, serum NMN levels sharply increased after intravenous NMN administration and then decreased rapidly within 15 min, while serum NAD levels remained unchanged during 30 min observation. Both substances displayed tissue accumulation over time and stored faster under MCAO conditions, with kidney having the highest concentrations. Particularly, NMN accumulated earlier than NAD in the brain. Moreover, NMN reduced cerebral infarction at 24 h post-MCAO. No acute toxicity was observed for 14 days. NRK1 and SLC12A8 involved in two pathways of NMN uptake exhibited the highest expressions in kidney and colon, respectively, among 11 different tissues. CONCLUSION: NMN distributes to various tissues after intravenous injection and has the ability to enter the brain to boost NAD levels, and exhibits safety and therapeutic effect on acute ischemic stroke injury. High renal distribution of NMN indicates its importance in the kidney.
    20. Hosseini L et al.: Nicotinamide Mononucleotide and Melatonin Alleviate Aging-induced Cognitive Impairment via Modulation of Mitochondrial Function and Apoptosis in the Prefrontal Cortex and Hippocampus. Neuroscience 2019. (PMID 31678348) [PubMed] [DOI] Given the fact that both melatonin and nicotinamide mononucleotide (NMN) act as pleiotropic agents in various age-related cognitive disorders, we aimed to investigate the effect of these compounds separately and together on the cognitive outcomes, mitochondrial function, and apoptosis in aged rats. Forty old and ten young (24 and 3 months old, respectively) male Wistar rats were randomly allocated into five groups: Young+Normal saline (NS), Aged+NS, Aged+Melatonin, Aged+NMN, and Aged+melatonin+NMN. Melatonin (10 mg/kg) and NMN (100 mg/kg) were administered, separately or in combination for 28 every other day in aged animals. The Barnes maze and novel object recognition test were used to assess spatial and episodic-like memories, respectively. Also, apoptosis and alterations in mitochondrial function including reactive oxygen species (ROS) and ATP levels as well as mitochondrial membrane potential were assessed in both prefrontal cortex (PFC) and hippocampus (HIP) regions. Behavioral results revealed that NMN and melatonin separately or in combination, alleviate aging-induced memory impairment. Moreover, agents' co-administration declined mitochondrial dysfunction and apoptotic cell count both in PFC and HIP regions. The agents separately or in combination (more potent) could induce neuroprotective effect and improve learning and memory in aged animals.
    21. Park JH et al.: Nicotinamide mononucleotide inhibits post-ischemic NAD(+) degradation and dramatically ameliorates brain damage following global cerebral ischemia. Neurobiol Dis 2016. (PMID 27425894) [PubMed] [DOI] [Full text] Nicotinamide adenine dinucleotide (NAD(+)) is an essential cofactor for multiple cellular metabolic reactions and has a central role in energy production. Brain ischemia depletes NAD(+) pools leading to bioenergetics failure and cell death. Nicotinamide mononucleotide (NMN) is utilized by the NAD(+) salvage pathway enzyme, nicotinamide adenylyltransferase (Nmnat) to generate NAD(+). Therefore, we examined whether NMN could protect against ischemic brain damage. Mice were subjected to transient forebrain ischemia and treated with NMN or vehicle at the start of reperfusion or 30min after the ischemic insult. At 2, 4, and 24h of recovery, the proteins poly-ADP-ribosylation (PAR), hippocampal NAD(+) levels, and expression levels of NAD(+) salvage pathway enzymes were determined. Furthermore, animal's neurologic outcome and hippocampal CA1 neuronal death was assessed after six days of reperfusion. NMN (62.5mg/kg) dramatically ameliorated the hippocampal CA1 injury and significantly improved the neurological outcome. Additionally, the post-ischemic NMN treatment prevented the increase in PAR formation and NAD(+) catabolism. Since the NMN administration did not affect animal's temperature, blood gases or regional cerebral blood flow during recovery, the protective effect was not a result of altered reperfusion conditions. These data suggest that administration of NMN at a proper dosage has a strong protective effect against ischemic brain injury.
    22. Ma XR et al.: Restoring nuclear entry of Sirtuin 2 in oligodendrocyte progenitor cells promotes remyelination during ageing. Nat Commun 2022. (PMID 35264567) [PubMed] [DOI] [Full text] The age-dependent decline in remyelination potential of the central nervous system during ageing is associated with a declined differentiation capacity of oligodendrocyte progenitor cells (OPCs). The molecular players that can enhance OPC differentiation or rejuvenate OPCs are unclear. Here we show that, in mouse OPCs, nuclear entry of SIRT2 is impaired and NAD+ levels are reduced during ageing. When we supplement β-nicotinamide mononucleotide (β-NMN), an NAD+ precursor, nuclear entry of SIRT2 in OPCs, OPC differentiation, and remyelination were rescued in aged animals. We show that the effects on myelination are mediated via the NAD+-SIRT2-H3K18Ac-ID4 axis, and SIRT2 is required for rejuvenating OPCs. Our results show that SIRT2 and NAD+ levels rescue the aged OPC differentiation potential to levels comparable to young age, providing potential targets to enhance remyelination during ageing.
    23. Fang T et al.: Nicotinamide mononucleotide ameliorates senescence in alveolar epithelial cells. MedComm (2020) 2021. (PMID 34766147) [PubMed] [DOI] [Full text] Alveolar epithelial cells (ACEs) gradually senescent as aging, which is one of the main causes of respiratory defense and function decline. Investigating the mechanisms of ACE senescence is important for understanding how the human respiratory system works. NAD+ is reported to reduce during the aging process. Supplementing NAD+ intermediates can activate sirtuin deacylases (SIRT1-SIRT7), which regulates the benefits of exercise and dietary restriction, reduce the level of intracellular oxidative stress, and improve mitochondrial function, thereby reversing cell senescence. We showed that nicotinamide mononucleotide (NMN) could effectively mitigate age-associated physiological decline in the lung of 8-10 months old C57BL/6 mice and bleomycin-induced pulmonary fibrosis in young mice of 6-8 weeks. Besides, the treatment of primary ACEs with NMN can markedly ameliorate cell senescence phenotype in vitro. These findings to improve the respiratory system function and reduce the incidence and mortality from respiratory diseases in the elderly are of great significance.
    24. Luo C et al.: Nicotinamide Mononucleotide Administration Restores Redox Homeostasis via the Sirt3-Nrf2 Axis and Protects Aged Mice from Oxidative Stress-Induced Liver Injury. J Proteome Res 2022. (PMID 35699728) [PubMed] [DOI] Altered adaptive homeostasis contributes to aging and lifespan regulation. In the present study, to characterize the mechanism of aging in mouse liver, we performed quantitative proteomics and found that the most upregulated proteins were related to the oxidation-reduction process. Further analysis revealed that malondialdehyde (MDA) and protein carbonyl (PCO) levels were increased, while nuclear Nrf2 and downstream genes were significantly increased, indicating that oxidative stress induced Nrf2 activation in aged mouse liver. Importantly, nicotinamide mononucleotide (NMN) administration decreased the oxidative stress and the nuclear Nrf2 and Nrf2 downstream gene levels. Indeed, aged mice treated with NMN improved stress resistance against acetaminophen (APAP)-induced liver injury, indicating that NMN restored Nrf2-mediated adaptive homeostasis. Further studies found that NMN increased Sirt3 activities to deacetylate age-associated acetylation at K68 and K122 in Sod2, while its effects on nuclear Nrf2 levels were diminished in Sirt3-deficient mice, suggesting that NMN-enhanced adaptive homeostasis was Sirt3-dependent. Taken together, we demonstrated that Nrf2-regulated adaptive homeostasis was decreased in aged mouse liver and NMN supplementation restored liver redox homeostasis via the Sirt3-Nrf2 axis and protected aged liver from oxidative stress-induced injury.
    25. Sims CA et al.: Nicotinamide mononucleotide preserves mitochondrial function and increases survival in hemorrhagic shock. JCI Insight 2018. (PMID 30185676) [PubMed] [DOI] [Full text] Hemorrhagic shock depletes nicotinamide adenine dinucleotide (NAD) and causes metabolic derangements that, in severe cases, cannot be overcome, even after restoration of blood volume and pressure. However, current strategies to treat acute blood loss do not target cellular metabolism. We hypothesized that supplemental nicotinamide mononucleotide (NMN), the immediate biosynthetic precursor to NAD, would support cellular energetics and enhance physiologic resilience to hemorrhagic shock. In a rodent model of decompensated hemorrhagic shock, rats receiving NMN displayed significantly reduced lactic acidosis and serum IL-6 levels, two strong predictors of mortality in human patients. In both livers and kidneys, NMN increased NAD levels and prevented mitochondrial dysfunction. Moreover, NMN preserved mitochondrial function in isolated hepatocytes cocultured with proinflammatory cytokines, indicating a cell-autonomous protective effect that is independent from the reduction in circulating IL-6. In kidneys, but not in livers, NMN was sufficient to prevent ATP loss following shock and resuscitation. Overall, NMN increased the time animals could sustain severe shock before requiring resuscitation by nearly 25% and significantly improved survival after resuscitation (P = 0.018), whether NMN was given as a pretreatment or only as an adjunct during resuscitation. Thus, we demonstrate that NMN substantially mitigates inflammation, improves cellular metabolism, and promotes survival following hemorrhagic shock.
    26. Martin AS et al.: Nicotinamide mononucleotide requires SIRT3 to improve cardiac function and bioenergetics in a Friedreich's ataxia cardiomyopathy model. JCI Insight 2017. (PMID 28724806) [PubMed] [DOI] [Full text] Increasing NAD+ levels by supplementing with the precursor nicotinamide mononucleotide (NMN) improves cardiac function in multiple mouse models of disease. While NMN influences several aspects of mitochondrial metabolism, the molecular mechanisms by which increased NAD+ enhances cardiac function are poorly understood. A putative mechanism of NAD+ therapeutic action exists via activation of the mitochondrial NAD+-dependent protein deacetylase sirtuin 3 (SIRT3). We assessed the therapeutic efficacy of NMN and the role of SIRT3 in the Friedreich's ataxia cardiomyopathy mouse model (FXN-KO). At baseline, the FXN-KO heart has mitochondrial protein hyperacetylation, reduced Sirt3 mRNA expression, and evidence of increased NAD+ salvage. Remarkably, NMN administered to FXN-KO mice restores cardiac function to near-normal levels. To determine whether SIRT3 is required for NMN therapeutic efficacy, we generated SIRT3-KO and SIRT3-KO/FXN-KO (double KO [dKO]) models. The improvement in cardiac function upon NMN treatment in the FXN-KO is lost in the dKO model, demonstrating that the effects of NMN are dependent upon cardiac SIRT3. Coupled with cardio-protection, SIRT3 mediates NMN-induced improvements in both cardiac and extracardiac metabolic function and energy metabolism. Taken together, these results serve as important preclinical data for NMN supplementation or SIRT3 activator therapy in Friedreich's ataxia patients.
    27. Zhang R et al.: Short-term administration of Nicotinamide Mononucleotide preserves cardiac mitochondrial homeostasis and prevents heart failure. J Mol Cell Cardiol 2017. (PMID 28882480) [PubMed] [DOI] [Full text] Heart failure is associated with mitochondrial dysfunction so that restoring or improving mitochondrial health is of therapeutic importance. Recently, reduction in NAD+ levels and NAD+-mediated deacetylase activity has been recognized as negative regulators of mitochondrial function. Using a cardiac specific KLF4 deficient mouse line that is sensitive to stress, we found mitochondrial protein hyperacetylation coupled with reduced Sirt3 and NAD+ levels in the heart before stress, suggesting that the KLF4-deficient heart is predisposed to NAD+-associated defects. Further, we demonstrated that short-term administration of Nicotinamide Mononucleotide (NMN) successfully protected the mutant mice from pressure overload-induced heart failure. Mechanically, we showed that NMN preserved mitochondrial ultrastructure, reduced ROS and prevented cell death in the heart. In cultured cardiomyocytes, NMN treatment significantly increased long-chain fatty acid oxidation despite no direct effect on pyruvate oxidation. Collectively, these results provide cogent evidence that hyperacetylation of mitochondrial proteins is critical in the pathogenesis of cardiac disease and that administration of NMN may serve as a promising therapy.
    28. Lee CF et al.: Normalization of NAD+ Redox Balance as a Therapy for Heart Failure. Circulation 2016. (PMID 27489254) [PubMed] [DOI] [Full text] BACKGROUND: Impairments of mitochondrial function in the heart are linked intricately to the development of heart failure, but there is no therapy for mitochondrial dysfunction. METHODS: We assessed the reduced/oxidized ratio of nicotinamide adenine dinucleotide (NADH/NAD(+) ratio) and protein acetylation in the failing heart. Proteome and acetylome analyses were followed by docking calculation, mutagenesis, and mitochondrial calcium uptake assays to determine the functional role of specific acetylation sites. The therapeutic effects of normalizing mitochondrial protein acetylation by expanding the NAD(+) pool also were tested. RESULTS: Increased NADH/NAD(+) and protein hyperacetylation, previously observed in genetic models of defective mitochondrial function, also are present in human failing hearts as well as in mouse hearts with pathologic hypertrophy. Elevation of NAD(+) levels by stimulating the NAD(+) salvage pathway suppressed mitochondrial protein hyperacetylation and cardiac hypertrophy, and improved cardiac function in responses to stresses. Acetylome analysis identified a subpopulation of mitochondrial proteins that was sensitive to changes in the NADH/NAD(+) ratio. Hyperacetylation of mitochondrial malate-aspartate shuttle proteins impaired the transport and oxidation of cytosolic NADH in the mitochondria, resulting in altered cytosolic redox state and energy deficiency. Furthermore, acetylation of oligomycin-sensitive conferring protein at lysine-70 in adenosine triphosphate synthase complex promoted its interaction with cyclophilin D, and sensitized the opening of mitochondrial permeability transition pore. Both could be alleviated by normalizing the NAD(+) redox balance either genetically or pharmacologically. CONCLUSIONS: We show that mitochondrial protein hyperacetylation due to NAD(+) redox imbalance contributes to the pathologic remodeling of the heart via 2 distinct mechanisms. Our preclinical data demonstrate a clear benefit of normalizing NADH/NAD(+) imbalance in the failing hearts. These findings have a high translational potential as the pharmacologic strategy of increasing NAD(+) precursors are feasible in humans.
    29. 29.0 29.1 29.2 Mills KF et al.: Long-Term Administration of Nicotinamide Mononucleotide Mitigates Age-Associated Physiological Decline in Mice. Cell Metab 2016. (PMID 28068222) [PubMed] [DOI] [Full text] NAD+ availability decreases with age and in certain disease conditions. Nicotinamide mononucleotide (NMN), a key NAD+ intermediate, has been shown to enhance NAD+ biosynthesis and ameliorate various pathologies in mouse disease models. In this study, we conducted a 12-month-long NMN administration to regular chow-fed wild-type C57BL/6N mice during their normal aging. Orally administered NMN was quickly utilized to synthesize NAD+ in tissues. Remarkably, NMN effectively mitigates age-associated physiological decline in mice. Without any obvious toxicity or deleterious effects, NMN suppressed age-associated body weight gain, enhanced energy metabolism, promoted physical activity, improved insulin sensitivity and plasma lipid profile, and ameliorated eye function and other pathophysiologies. Consistent with these phenotypes, NMN prevented age-associated gene expression changes in key metabolic organs and enhanced mitochondrial oxidative metabolism and mitonuclear protein imbalance in skeletal muscle. These effects of NMN highlight the preventive and therapeutic potential of NAD+ intermediates as effective anti-aging interventions in humans.
    30. Chen X et al.: Neuroprotective effects and mechanisms of action of nicotinamide mononucleotide (NMN) in a photoreceptor degenerative model of retinal detachment. Aging (Albany NY) 2020. (PMID 33373320) [PubMed] [DOI] [Full text] Currently, no pharmacotherapy has been proven effective in treating photoreceptor degeneration in patients. Discovering readily available and safe neuroprotectants is therefore highly sought after. Here, we investigated nicotinamide mononucleotide (NMN), a precursor of nicotinamide adenine dinucleotide (NAD+), in a retinal detachment (RD) induced photoreceptor degeneration. NMN administration after RD resulted in a significant reduction of TUNEL+ photoreceptors, CD11b+ macrophages, and GFAP labeled glial activation; a normalization of protein carbonyl content (PCC), and a preservation of the outer nuclear layer (ONL) thickness. NMN administration significantly increased NAD+ levels, SIRT1 protein expression, and heme oxygenase-1 (HO-1) expression. Delayed NMN administration still exerted protective effects after RD. Mechanistic in vitro studies using 661W cells revealed a SIRT1/HO-1 signaling as a downstream effector of NMN-mediated protection under oxidative stress and LPS stimulation. In conclusion, NMN administration exerts neuroprotective effects on photoreceptors after RD and oxidative injury, suggesting a therapeutic avenue to treating photoreceptor degeneration.
    31. Uddin GM et al.: Head to Head Comparison of Short-Term Treatment with the NAD(+) Precursor Nicotinamide Mononucleotide (NMN) and 6 Weeks of Exercise in Obese Female Mice. Front Pharmacol 2016. (PMID 27594836) [PubMed] [DOI] [Full text] Obesity is well known to be a major cause of several chronic metabolic diseases, which can be partially counteracted by exercise. This is due, in part, to an upregulation of mitochondrial activity through increased nicotinamide adenine dinucleotide (NAD(+)). Recent studies have shown that NAD(+) levels can be increased by using the NAD(+) precursor, nicotinamide mononucleotide (NMN) leading to the suggestion that NMN could be a useful intervention in diet related metabolic disorders. In this study we compared the metabolic, and especially mitochondrial-associated, effects of exercise and NMN in ameliorating the consequences of high-fat diet (HFD) induced obesity in mice. Sixty female 5 week old C57BL6/J mice were allocated across five groups: Chow sedentary: CS; Chow exercise: CEX; HFD sedentary: HS; HFD NMN: HNMN; HFD exercise: HEX (12/group). After 6 weeks of diet, exercise groups underwent treadmill exercise (15 m/min for 45 min), 6 days per week for 6 weeks. NMN or vehicle (500 mg/kg body weight) was injected (i.p.) daily for the last 17 days. No significant alteration in body weight was observed in response to exercise or NMN. The HFD significantly altered adiposity, glucose tolerance, plasma insulin, NADH levels and citrate synthase activity in muscle and liver. HEX and HNMN groups both showed significantly improved glucose tolerance compared to the HS group. NAD(+) levels were increased significantly both in muscle and liver by NMN whereas exercise increased NAD(+) only in muscle. Both NMN and exercise ameliorated the HFD-induced reduction in liver citrate synthase activity. However, exercise, but not NMN, ameliorated citrate synthase activity in muscle. Overall these data suggest that while exercise and NMN-supplementation can induce similar reversal of the glucose intolerance induced by obesity, they are associated with tissue-specific effects and differential alterations to mitochondrial function in muscle and liver.
    32. Kiss T et al.: Nicotinamide mononucleotide (NMN) supplementation promotes anti-aging miRNA expression profile in the aorta of aged mice, predicting epigenetic rejuvenation and anti-atherogenic effects. Geroscience 2019. (PMID 31463647) [PubMed] [DOI] [Full text] Understanding molecular mechanisms involved in vascular aging is essential to develop novel interventional strategies for treatment and prevention of age-related vascular pathologies. Recent studies provide critical evidence that vascular aging is characterized by NAD+ depletion. Importantly, in aged mice, restoration of cellular NAD+ levels by treatment with the NAD+ booster nicotinamide mononucleotide (NMN) exerts significant vasoprotective effects, improving endothelium-dependent vasodilation, attenuating oxidative stress, and rescuing age-related changes in gene expression. Strong experimental evidence shows that dysregulation of microRNAs (miRNAs) has a role in vascular aging. The present study was designed to test the hypothesis that age-related NAD+ depletion is causally linked to dysregulation of vascular miRNA expression. A corollary hypothesis is that functional vascular rejuvenation in NMN-treated aged mice is also associated with restoration of a youthful vascular miRNA expression profile. To test these hypotheses, aged (24-month-old) mice were treated with NMN for 2 weeks and miRNA signatures in the aortas were compared to those in aortas obtained from untreated young and aged control mice. We found that protective effects of NMN treatment on vascular function are associated with anti-aging changes in the miRNA expression profile in the aged mouse aorta. The predicted regulatory effects of NMN-induced differentially expressed miRNAs in aged vessels include anti-atherogenic effects and epigenetic rejuvenation. Future studies will uncover the mechanistic role of miRNA gene expression regulatory networks in the anti-aging effects of NAD+ booster treatments and determine the links between miRNAs regulated by NMN and sirtuin activators and miRNAs known to act in the conserved pathways of aging and major aging-related vascular diseases.
    33. Kiss T et al.: Nicotinamide mononucleotide (NMN) supplementation promotes neurovascular rejuvenation in aged mice: transcriptional footprint of SIRT1 activation, mitochondrial protection, anti-inflammatory, and anti-apoptotic effects. Geroscience 2020. (PMID 32056076) [PubMed] [DOI] [Full text] Aging-induced structural and functional alterations of the neurovascular unit lead to impairment of neurovascular coupling responses, dysregulation of cerebral blood flow, and increased neuroinflammation, all of which contribute importantly to the pathogenesis of age-related vascular cognitive impairment (VCI). There is increasing evidence showing that a decrease in NAD+ availability with age plays a critical role in age-related neurovascular and cerebromicrovascular dysfunction. Our recent studies demonstrate that restoring cellular NAD+ levels in aged mice rescues neurovascular function, increases cerebral blood flow, and improves performance on cognitive tasks. To determine the effects of restoring cellular NAD+ levels on neurovascular gene expression profiles, 24-month-old C57BL/6 mice were treated with nicotinamide mononucleotide (NMN), a key NAD+ intermediate, for 2 weeks. Transcriptome analysis of preparations enriched for cells of the neurovascular unit was performed by RNA-seq. Neurovascular gene expression signatures in NMN-treated aged mice were compared with those in untreated young and aged control mice. We identified 590 genes differentially expressed in the aged neurovascular unit, 204 of which are restored toward youthful expression levels by NMN treatment. The transcriptional footprint of NMN treatment indicates that increased NAD+ levels promote SIRT1 activation in the neurovascular unit, as demonstrated by analysis of upstream regulators of differentially expressed genes as well as analysis of the expression of known SIRT1-dependent genes. Pathway analysis predicts that neurovascular protective effects of NMN are mediated by the induction of genes involved in mitochondrial rejuvenation, anti-inflammatory, and anti-apoptotic pathways. In conclusion, the recently demonstrated protective effects of NMN treatment on neurovascular function can be attributed to multifaceted sirtuin-mediated anti-aging changes in the neurovascular transcriptome. Our present findings taken together with the results of recent studies using mitochondria-targeted interventions suggest that mitochondrial rejuvenation is a critical mechanism to restore neurovascular health and improve cerebral blood flow in aging.
    34. de Picciotto NE et al.: Nicotinamide mononucleotide supplementation reverses vascular dysfunction and oxidative stress with aging in mice. Aging Cell 2016. (PMID 26970090) [PubMed] [DOI] [Full text] We tested the hypothesis that supplementation of nicotinamide mononucleotide (NMN), a key NAD(+) intermediate, increases arterial SIRT1 activity and reverses age-associated arterial dysfunction and oxidative stress. Old control mice (OC) had impaired carotid artery endothelium-dependent dilation (EDD) (60 ± 5% vs. 84 ± 2%), a measure of endothelial function, and nitric oxide (NO)-mediated EDD (37 ± 4% vs. 66 ± 6%), compared with young mice (YC). This age-associated impairment in EDD was restored in OC by the superoxide (O2-) scavenger TEMPOL (82 ± 7%). OC also had increased aortic pulse wave velocity (aPWV, 464 ± 31 cm s(-1) vs. 337 ± 3 cm s(-1) ) and elastic modulus (EM, 6407 ± 876 kPa vs. 3119 ± 471 kPa), measures of large elastic artery stiffness, compared with YC. OC had greater aortic O2- production (2.0 ± 0.1 vs. 1.0 ± 0.1 AU), nitrotyrosine abundance (a marker of oxidative stress), and collagen-I, and reduced elastin and vascular SIRT1 activity, measured by the acetylation status of the p65 subunit of NFκB, compared with YC. Supplementation with NMN in old mice restored EDD (86 ± 2%) and NO-mediated EDD (61 ± 5%), reduced aPWV (359 ± 14 cm s(-1) ) and EM (3694 ± 315 kPa), normalized O2- production (0.9 ± 0.1 AU), decreased nitrotyrosine, reversed collagen-I, increased elastin, and restored vascular SIRT1 activity. Acute NMN incubation in isolated aortas increased NAD(+) threefold and manganese superoxide dismutase (MnSOD) by 50%. NMN supplementation may represent a novel therapy to restore SIRT1 activity and reverse age-related arterial dysfunction by decreasing oxidative stress.
    35. Das A et al.: Impairment of an Endothelial NAD+-H2S Signaling Network Is a Reversible Cause of Vascular Aging. Cell 2018. (PMID 29570999) [PubMed] [DOI] [Full text] A decline in capillary density and blood flow with age is a major cause of mortality and morbidity. Understanding why this occurs is key to future gains in human health. NAD precursors reverse aspects of aging, in part, by activating sirtuin deacylases (SIRT1-SIRT7) that mediate the benefits of exercise and dietary restriction (DR). We show that SIRT1 in endothelial cells is a key mediator of pro-angiogenic signals secreted from myocytes. Treatment of mice with the NAD+ booster nicotinamide mononucleotide (NMN) improves blood flow and increases endurance in elderly mice by promoting SIRT1-dependent increases in capillary density, an effect augmented by exercise or increasing the levels of hydrogen sulfide (H2S), a DR mimetic and regulator of endothelial NAD+ levels. These findings have implications for improving blood flow to organs and tissues, increasing human performance, and reestablishing a virtuous cycle of mobility in the elderly.
    36. Ru M et al.: Nicotinamide mononucleotide supplementation protects the intestinal function in aging mice and D-galactose induced senescent cells. Food Funct 2022. (PMID 35678708) [PubMed] [DOI] The nicotinamide adenine dinucleotide (NAD+) level shows a temporal decrease during the aging process, which has been deemed as an aging hallmark. Nicotinamide mononucleotide (NMN), a key NAD+ precursor, shows the potential to retard the age-associated functional decline in organs. In the current study, to explore whether NMN has an impact on the intestine during the aging process, the effects of NMN supplementation on the intestinal morphology, microbiota, and NAD+ content, as well as its anti-inflammatory, anti-oxidative and barrier functions were investigated in aging mice and D-galactose (D-gal) induced senescent IPEC-J2 cells. The results showed that 4 months of NMN administration had little impact on the colonic microbiota and NAD+ content in aging mice, while it significantly increased the jejunal NAD+ content and improved the jejunal structure including increasing the villus length and shortening the crypt. Moreover, NMN supplementation significantly up-regulated the mRNA expression of SIRT3, SIRT6, nuclear factor E2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), the catalytic subunit of glutamate-cysteine ligase (GCLC), superoxide dismutase 2 (SOD2), occludin, and claudin-1, but down-regulated the mRNA expression of tumor necrosis factor alpha (TNF-α). Specifically, in the D-gal induced senescent IPEC-J2 cells, 500 μM NMN restored the increased mRNA expression of interleukin 6 (IL6ST), IL-1A, nuclear factor (NF-κB1), and claudin-1 to normal levels to some extent. Furthermore, NMN treatment significantly affected the mRNA expression of antioxidant enzymes including NQO1, GCLC, SOD 2 and 3, and GSH-PX1, 3 and 4. In addition, 200 μM NMN enhanced the cell viability and total antioxidant capacity and lowered the reactive oxygen species level of senescent IPEC-J2 cells. Notably, NMN restored the down-regulated protein expression of occludin and claudin-1 induced by D-gal. The above data demonstrated the potential of NMN in ameliorating the structural and functional decline in the intestine during aging.
    37. Yao Z et al.: Nicotinamide mononucleotide inhibits JNK activation to reverse Alzheimer disease. Neurosci Lett 2017. (PMID 28330719) [PubMed] [DOI] Amyloid-β (Aβ) oligomers have been accepted as major neurotoxic agents in the therapy of Alzheimer's disease (AD). It has been shown that the activity of nicotinamide adenine dinucleotide (NAD+) is related with the decline of Aβ toxicity in AD. Nicotinamide mononucleotide (NMN), the important precursor of NAD+, is produced during the reaction of nicotinamide phosphoribosyl transferase (Nampt). This study aimed to figure out the potential therapeutic effects of NMN and its underlying mechanisms in APPswe/PS1dE9 (AD-Tg) mice. We found that NMN gave rise to a substantial improvement in behavioral measures of cognitive impairments compared to control AD-Tg mice. In addition, NMN treatment significantly decreased β-amyloid production, amyloid plaque burden, synaptic loss, and inflammatory responses in transgenic animals. Mechanistically, NMN effectively controlled JNK activation. Furthermore, NMN potently progressed nonamyloidogenic amyloid precursor protein (APP) and suppressed amyloidogenic APP by mediating the expression of APP cleavage secretase in AD-Tg mice. Based on our findings, it was suggested that NMN substantially decreases multiple AD-associated pathological characteristically at least partially by the inhibition of JNK activation.
    38. Wei CC et al.: Nicotinamide mononucleotide attenuates brain injury after intracerebral hemorrhage by activating Nrf2/HO-1 signaling pathway. Sci Rep 2017. (PMID 28386082) [PubMed] [DOI] [Full text] Replenishment of NAD+ has been shown to protect against brain disorders such as amyotrophic lateral sclerosis and ischemic stroke. However, whether this intervention has therapeutic effects in intracerebral hemorrhage (ICH) is unknown. In this study, we sought to determine the potential therapeutic value of replenishment of NAD+ in ICH. In a collagenase-induced ICH (cICH) mouse model, nicotinamide mononucleotide (NMN), a key intermediate of nicotinamide adenine dinucleotide (NAD+) biosynthesis, was administrated at 30 minutes post cICH from tail vein to replenish NAD+. NMN treatment did not decrease hematoma volume and hemoglobin content. However, NMN treatment significantly reduced brain edema, brain cell death, oxidative stress, neuroinflammation, intercellular adhesion molecule-1 expression, microglia activation and neutrophil infiltration in brain hemorrhagic area. Mechanistically, NMN enhanced the expression of two cytoprotective proteins: heme oxygenase 1 (HO-1) and nuclear factor-like 2 (Nrf2). Moreover, NMN increased the nuclear translocation of Nrf2 for its activation. Finally, a prolonged NMN treatment for 7 days markedly promoted the recovery of body weight and neurological function. These results demonstrate that NMN treats brain injury in ICH by suppressing neuroinflammation/oxidative stress. The activation of Nrf2/HO-1 signaling pathway may contribute to the neuroprotection of NMN in ICH.
    39. Zhou X et al.: β-Nicotinamide Mononucleotide (NMN) Administrated by Intraperitoneal Injection Mediates Protection Against UVB-Induced Skin Damage in Mice. J Inflamm Res 2021. (PMID 34675595) [PubMed] [DOI] [Full text] OBJECTIVE: Ultraviolet light is an important environmental factor that induces skin oxidation, inflammation, and other diseases. Nicotinamide mononucleotide (NMN) has the effect of anti-oxidation and improving various physiological processes. This study explores the protective effect of NMN monomers given via intraperitoneal injection on UVB-induced photodamage. METHODS: We used a murine model of UVB-induced photodamage to evaluate the effect of an NMN monomer on photoaging skin by assessing skin and liver tissue sections, serum and skin oxidative stress levels, inflammatory markers, mRNA expression, and protein expression of skin- and liver-related genes. RESULTS: The results showed that NMN treatment blocked UVB-induced photodamage in mice, maintaining normal structure and amount of collagen fibers, normal thickness of epidermis and dermis, reducing the production of mast cells, and maintaining complete organized skin structure. NMN intraperitoneal injection also maintained the normal morphology of the mouse liver after UVB exposure. Meanwhile, NMN intraperitoneal injection was found to increase antioxidant ability and regulate the proinflammatory response of the skin and liver to UVB irradiation by enhancing the activity of antioxidant enzymes, release of anti-inflammatory cytokines, reduction of hydrogen peroxide production (H2O2), and decreased inflammatory cytokines. Furthermore, RT-qPCR results indicated that NMN reduced oxidative stress of skin and liver by promoting the activation of the AMP-activated protein kinase (AMPK) signaling pathway and further increasing the expression of downstream antioxidant genes of AMPK. RT-qPCR results also revealed that NMN treatment could downregulate the mRNA expression of interleukin (IL)-6, interleukin (IL)-1β, and tumor necrosis factor (TNF)-α, and upregulate NF-kappa-B inhibitor-α (IκB-α) and interleukin (IL)-10 by inhibiting the activation of nuclear factor-κBp65 (NFκB-p65). Finally, NMN upregulated AMPK, IκB-α, SOD1, and CAT in the skin and downregulated NF-κBp65 protein expression, which is in line with the RT-qPCR results. CONCLUSION: Based on the above results, NMN monomer treatment with intraperitoneal injection also block the photodamage caused by UVB irradiation in mice by regulating the oxidative stress response and inflammatory response.
    40. Miao Y et al.: Nicotinamide Mononucleotide Supplementation Reverses the Declining Quality of Maternally Aged Oocytes. Cell Rep 2020. (PMID 32755581) [PubMed] [DOI] Advanced maternal age is highly associated with a decline in oocyte quality, but effective approaches to improve it have still not been fully determined. Here, we report that in vivo supplementation of nicotinamide mononucleotide (NMN) efficaciously improves the quality of oocytes from naturally aged mice by recovering nicotinamide adenine dinucleotide (NAD+) levels. NMN supplementation not only increases ovulation of aged oocytes but also enhances their meiotic competency and fertilization ability by maintaining the normal spindle/chromosome structure and the dynamics of the cortical granule component ovastacin. Moreover, single-cell transcriptome analysis shows that the beneficial effect of NMN on aged oocytes is mediated by restoration of mitochondrial function, eliminating the accumulated ROS to suppress apoptosis. Collectively, our data reveal that NMN supplementation is a feasible approach to protect oocytes from advanced maternal age-related deterioration, contributing to the improvement of reproductive outcome of aged women and assisted reproductive technology.
    41. 41.0 41.1 Bertoldo MJ et al.: NAD+ Repletion Rescues Female Fertility during Reproductive Aging. Cell Rep 2020. (PMID 32049001) [PubMed] [DOI] [Full text] Reproductive aging in female mammals is an irreversible process associated with declining oocyte quality, which is the rate-limiting factor to fertility. Here, we show that this loss of oocyte quality with age accompanies declining levels of the prominent metabolic cofactor nicotinamide adenine dinucleotide (NAD+). Treatment with the NAD+ metabolic precursor nicotinamide mononucleotide (NMN) rejuvenates oocyte quality in aged animals, leading to restoration in fertility, and this can be recapitulated by transgenic overexpression of the NAD+-dependent deacylase SIRT2, though deletion of this enzyme does not impair oocyte quality. These benefits of NMN extend to the developing embryo, where supplementation reverses the adverse effect of maternal age on developmental milestones. These findings suggest that late-life restoration of NAD+ levels represents an opportunity to rescue female reproductive function in mammals.
    42. Ma D et al.: Nicotinamide mononucleotide improves spermatogenic function in streptozotocin-induced diabetic mice via modulating the glycolysis pathway. Acta Biochim Biophys Sin (Shanghai) 2022. (PMID 35929593) [PubMed] [DOI] [Full text] Spermatogenic dysfunction is one of the major secondary complications of diabetes; however, the underlying mechanisms remain ill-defined, and there is no available drug or strategy for the radical treatment of diabetic spermatogenic dysfunction. Therefore, the objective of this study is to investigate the protective effects of nicotinamide mononucleotide (NMN) on testicular spermatogenic function in streptozotocin (STZ)-induced diabetic mice. The results show that oral administration of NMN significantly increases the body and testis weight and the number of sperms. Moreover, the abnormal sperm count and the rate of sperm malformation are significantly decreased compared with the saline-treated diabetic mice. Histological analysis reveals that NMN treatment significantly increases the area and diameter of seminiferous tubules, accompanied by an increased number of spermatogenic cells and sperms. Immunohistochemistry and qRT-PCR results show that NMN increases Bcl-2 expression and decreases Bax expression in the testis. NMN also increases the protein expression of Vimentin and the mRNA expressions of WT1 and GATA4. In addition, qRT-PCR, western blot analysis and immunohistochemistry results also show that NMN increases the expressions of glycolysis-related rate-limiting enzymes including HK2, PKM2, and LDHA. In summary, this study demonstrates the protective effects of NMN on the testis in an STZ-induced diabetic mice model. NMN exerts its protective effects via reducing spermatogenic cell apoptosis by regulating glycolysis of Sertoli cells in diabetic mice. This study provides an experimental basis for the future clinical application of NMN in diabetes-induced spermatogenic dysfunction.
    43. 43.0 43.1 43.2 43.3 Kim M et al.: Effect of 12-Week Intake of Nicotinamide Mononucleotide on Sleep Quality, Fatigue, and Physical Performance in Older Japanese Adults: A Randomized, Double-Blind Placebo-Controlled Study. Nutrients 2022. (PMID 35215405) [PubMed] [DOI] [Full text] Deteriorating sleep quality and physical or mental fatigue in older adults leads to decreased quality of life and increased mortality rates. This study investigated the effects of the time-dependent intake of nicotinamide mononucleotide (NMN) on sleep quality, fatigue, and physical performance in older adults. This randomized, double-blind placebo-controlled study evaluated 108 participants divided into four groups (NMN_AM; antemeridian, NMN_PM; post meridian, Placebo_AM, Placebo_PM). NMN (250 mg) or placebo was administered once a day for 12 weeks. Sleep quality was evaluated using the Pittsburgh Sleep Quality Index. Fatigue was evaluated using the "Jikaku-sho shirabe" questionnaire. Grip strength, 5-times sit-to-stand (5-STS), timed up and go, and 5-m habitual walk were evaluated to assess the physical performance. Significant interactions were observed between 5-STS and drowsiness. 5-STS of all groups on post-intervention and drowsiness of the NMN_PM and Placebo_PM groups on mid- and post-intervention showed significant improvement compared with those in pre-intervention. The NMN_PM group demonstrated the largest effect size for 5-STS (d = 0.72) and drowsiness (d = 0.64). Overall, NMN intake in the afternoon effectively improved lower limb function and reduced drowsiness in older adults. These findings suggest the potential of NMN in preventing loss of physical performance and improving fatigue in older adults.
    44. 44.0 44.1 Liao B et al.: Nicotinamide mononucleotide supplementation enhances aerobic capacity in amateur runners: a randomized, double-blind study. J Int Soc Sports Nutr 2021. (PMID 34238308) [PubMed] [DOI] [Full text] BACKGROUND: Recent studies in rodents indicate that a combination of exercise training and supplementation with nicotinamide adenine dinucleotide (NAD+) precursors has synergistic effects. However, there are currently no human clinical trials analyzing this. OBJECTIVE: This study investigates the effects of a combination of exercise training and supplementation with nicotinamide mononucleotide (NMN), the immediate precursor of NAD+, on cardiovascular fitness in healthy amateur runners. METHODS: A six-week randomized, double-blind, placebo-controlled, four-arm clinical trial including 48 young and middle-aged recreationally trained runners of the Guangzhou Pearl River running team was conducted. The participants were randomized into four groups: the low dosage group (300 mg/day NMN), the medium dosage group (600 mg/day NMN), the high dosage group (1200 mg/day NMN), and the control group (placebo). Each group consisted of ten male participants and two female participants. Each training session was 40-60 min, and the runners trained 5-6 times each week. Cardiopulmonary exercise testing was performed at baseline and after the intervention, at 6 weeks, to assess the aerobic capacity of the runners. RESULTS: Analysis of covariance of the change from baseline over the 6 week treatment showed that the oxygen uptake (VO2), percentages of maximum oxygen uptake (VO2max), power at first ventilatory threshold, and power at second ventilatory threshold increased to a higher degree in the medium and high dosage groups compared with the control group. However, there was no difference in VO2max, O2-pulse, VO2 related to work rate, and peak power after the 6 week treatment from baseline in any of these groups. CONCLUSION: NMN increases the aerobic capacity of humans during exercise training, and the improvement is likely the result of enhanced O2 utilization of the skeletal muscle. TRIAL REGISTRATION NUMBER: ChiCTR2000035138 .
    45. 45.0 45.1 Niu KM et al.: The Impacts of Short-Term NMN Supplementation on Serum Metabolism, Fecal Microbiota, and Telomere Length in Pre-Aging Phase. Front Nutr 2021. (PMID 34912838) [PubMed] [DOI] [Full text] Aging is a natural process with concomitant changes in the gut microbiota and associate metabolomes. Beta-nicotinamide mononucleotide, an important NAD+ intermediate, has drawn increasing attention to retard the aging process. We probed the changes in the fecal microbiota and metabolomes of pre-aging male mice (C57BL/6, age: 16 months) following the oral short-term administration of nicotinamide mononucleotide (NMN). Considering the telomere length as a molecular gauge for aging, we measured this in the peripheral blood mononuclear cells (PBMC) of pre-aging mice and human volunteers (age: 45-60 years old). Notably, the NMN administration did not influence the body weight and feed intake significantly during the 40 days in pre-aging mice. Metabolomics suggested 266 upregulated and 58 downregulated serum metabolites. We identified 34 potential biomarkers linked with the nicotinamide, purine, and proline metabolism pathways. Nicotinamide mononucleotide significantly reduced the fecal bacterial diversity (p < 0.05) with the increased abundance of Helicobacter, Mucispirillum, and Faecalibacterium, and lowered Akkermansia abundance associated with nicotinamide metabolism. We propose that this reshaped microbiota considerably lowered the predicated functions of aging with improved immune and cofactors/vitamin metabolism. Most notably, the telomere length of PBMC was significantly elongated in the NMN-administered mice and humans. Taken together, these findings suggest that oral NMN supplementation in the pre-aging stage might be an effective strategy to retard aging. We recommend further studies to unravel the underlying molecular mechanisms and comprehensive clinical trials to validate the effects of NMN on aging.
    46. https://www.dremilnutrition.com/post/will-i-get-side-effects-from-my-nmn-intake#:~:text=Potential%20NMN%20Side%20Effects%20%2B%20Other%20Safety%20Concerns&text=When%20taken%20at%20higher%20doses,amounts%20that%20are%20too%20high.
    47. 47.0 47.1 https://renuebyscience.com/forums/viewtopic.php?t=2575
    48. Peek CB et al.: Circadian clock NAD+ cycle drives mitochondrial oxidative metabolism in mice. Science 2013. (PMID 24051248) [PubMed] [DOI] [Full text] Circadian clocks are self-sustained cellular oscillators that synchronize oxidative and reductive cycles in anticipation of the solar cycle. We found that the clock transcription feedback loop produces cycles of nicotinamide adenine dinucleotide (NAD(+)) biosynthesis, adenosine triphosphate production, and mitochondrial respiration through modulation of mitochondrial protein acetylation to synchronize oxidative metabolic pathways with the 24-hour fasting and feeding cycle. Circadian control of the activity of the NAD(+)-dependent deacetylase sirtuin 3 (SIRT3) generated rhythms in the acetylation and activity of oxidative enzymes and respiration in isolated mitochondria, and NAD(+) supplementation restored protein deacetylation and enhanced oxygen consumption in circadian mutant mice. Thus, circadian control of NAD(+) bioavailability modulates mitochondrial oxidative function and organismal metabolism across the daily cycles of fasting and feeding.
    49. Levine DC et al.: NAD+ Controls Circadian Reprogramming through PER2 Nuclear Translocation to Counter Aging. Mol Cell 2020. (PMID 32369735) [PubMed] [DOI] [Full text] Disrupted sleep-wake and molecular circadian rhythms are a feature of aging associated with metabolic disease and reduced levels of NAD+, yet whether changes in nucleotide metabolism control circadian behavioral and genomic rhythms remains unknown. Here, we reveal that supplementation with the NAD+ precursor nicotinamide riboside (NR) markedly reprograms metabolic and stress-response pathways that decline with aging through inhibition of the clock repressor PER2. NR enhances BMAL1 chromatin binding genome-wide through PER2K680 deacetylation, which in turn primes PER2 phosphorylation within a domain that controls nuclear transport and stability and that is mutated in human advanced sleep phase syndrome. In old mice, dampened BMAL1 chromatin binding, transcriptional oscillations, mitochondrial respiration rhythms, and late evening activity are restored by NAD+ repletion to youthful levels with NR. These results reveal effects of NAD+ on metabolism and the circadian system with aging through the spatiotemporal control of the molecular clock.
    50. 2021-12-27 - Interview Dr. David Sinclair - Huberman Lab Podcast - The Biology of Slowing & Reversing Aging
    51. 51.0 51.1 Pencina KM et al.: Nicotinamide Adenine Dinucleotide Augmentation in Overweight or Obese Middle-Aged and Older Adults: A Physiologic Study. J Clin Endocrinol Metab 2023. (PMID 36740954) [PubMed] [DOI] CONTEXT: Nicotinamide adenine dinucleotide (NAD) levels decline with aging and age-related decline in NAD has been postulated to contribute to age-related diseases. OBJECTIVE: We evaluated the safety and physiologic effects of NAD augmentation by administering its precursor, β-nicotinamide mononucleotide (MIB-626, Metro International Biotech, Worcester, MA), in adults at risk for age-related conditions. METHODS: Thirty overweight or obese adults, ≥ 45 years, were randomized in a 2:1 ratio to 2 MIB-626 tablets each containing 500 mg of microcrystalline β-nicotinamide mononucleotide or placebo twice daily for 28 days. Study outcomes included safety; NAD and its metabolome; body weight; liver, muscle, and intra-abdominal fat; insulin sensitivity; blood pressure; lipids; physical performance, and muscle bioenergetics. RESULTS: Adverse events were similar between groups. MIB-626 treatment substantially increased circulating concentrations of NAD and its metabolites. Body weight (difference -1.9 [-3.3, -0.5] kg, P = .008); diastolic blood pressure (difference -7.01 [-13.44, -0.59] mmHg, P = .034); total cholesterol (difference -26.89 [-44.34, -9.44] mg/dL, P = .004), low-density lipoprotein (LDL) cholesterol (-18.73 [-31.85, -5.60] mg/dL, P = .007), and nonhigh-density lipoprotein cholesterol decreased significantly more in the MIB-626 group than placebo. Changes in muscle strength, muscle fatigability, aerobic capacity, and stair-climbing power did not differ significantly between groups. Insulin sensitivity and hepatic and intra-abdominal fat did not change in either group. CONCLUSIONS: MIB-626 administration in overweight or obese, middle-aged and older adults safely increased circulating NAD levels, and significantly reduced total LDL and non-HDL cholesterol, body weight, and diastolic blood pressure. These data provide the rationale for larger trials to assess the efficacy of NAD augmentation in improving cardiometabolic outcomes in older adults.
    52. https://healthnews.com/longevity/longevity-supplements/proper-storage-of-nicotinamide-mononucleotide-powder/
    53. https://age-science.com/wp-content/uploads/2021/08/Age-Science-Research-on-NMN-stability-6-month.pdf
    54. Sharma A et al.: Potential Synergistic Supplementation of NAD+ Promoting Compounds as a Strategy for Increasing Healthspan. Nutrients 2023. (PMID 36678315) [PubMed] [DOI] [Full text] Disrupted biological function, manifesting through the hallmarks of aging, poses one of the largest threats to healthspan and risk of disease development, such as metabolic disorders, cardiovascular ailments, and neurodegeneration. In recent years, numerous geroprotectors, senolytics, and other nutraceuticals have emerged as potential disruptors of aging and may be viable interventions in the immediate state of human longevity science. In this review, we focus on the decrease in nicotinamide adenine dinucleotide (NAD+) with age and the supplementation of NAD+ precursors, such as nicotinamide mononucleotide (NMN) or nicotinamide riboside (NR), in combination with other geroprotective compounds, to restore NAD+ levels present in youth. Furthermore, these geroprotectors may enhance the efficacy of NMN supplementation while concurrently providing their own numerous health benefits. By analyzing the prevention of NAD+ degradation through the inhibition of CD38 or supporting protective downstream agents of SIRT1, we provide a potential framework of the CD38/NAD+/SIRT1 axis through which geroprotectors may enhance the efficacy of NAD+ precursor supplementation and reduce the risk of age-related diseases, thereby potentiating healthspan in humans.
    55. Tomé-Carneiro J et al.: Resveratrol and clinical trials: the crossroad from in vitro studies to human evidence. Curr Pharm Des 2013. (PMID 23448440) [PubMed] [DOI] [Full text] Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a non-flavonoid polyphenol that may be present in a limited number of foodstuffs such as grapes and red wine. Resveratrol has been reported to exert a plethora of health benefits through many different mechanisms of action. This versatility and presence in the human diet have drawn the worldwide attention of many research groups over the past twenty years, which has resulted in a huge output of in vitro and animal (preclinical) studies. In line with this expectation, many resveratrol- based nutraceuticals are consumed all over the world with questionable clinical/scientific support. In fact, the confirmation of these benefits in humans through randomized clinical trials is still very limited. The vast majority of preclinical studies have been performed using assay conditions with a questionable extrapolation to humans, i.e. too high concentrations with potential safety concerns (adverse effects and drug interactions), short-term exposures, in vitro tests carried out with non-physiological metabolites and/or concentrations, etc. Unfortunately, all these hypothesis-generating studies have contributed to increased the number of 'potential' benefits and mechanisms of resveratrol but confirmation in humans is very limited. Therefore, there are many issues that should be addressed to avoid an apparent endless loop in resveratrol research. The so-called 'Resveratrol Paradox', i.e., low bioavailability but high bioactivity, is a conundrum not yet solved in which the final responsible actor (if any) for the exerted effects has not yet been unequivocally identified. It is becoming evident that resveratrol exerts cardioprotective benefits through the improvement of inflammatory markers, atherogenic profile, glucose metabolism and endothelial function. However, safety concerns remain unsolved regarding chronic consumption of high RES doses, specially in medicated people. This review will focus on the currently available evidence regarding resveratrol's effects on humans obtained from randomized clinical trials. In addition, we will provide a critical outlook for further research on this molecule that is evolving from a minor dietary compound to a possible multi-target therapeutic drug.
    56. Chan EWC, Wong CW, Tan YH, Foo JPY, Wong SK, Chan HT. Resveratrol and pterostilbene: A comparative overview of their chemistry, biosynthesis, plant sources and pharmacological properties. J Appl Pharm Sci, 2019; 9(07):124–129. [DOI]
    57. Riche DM et al.: Analysis of safety from a human clinical trial with pterostilbene. J Toxicol 2013. (PMID 23431291) [PubMed] [DOI] [Full text] Objectives. The purpose of this trial was to evaluate the safety of long-term pterostilbene administration in humans. Methodology. The trial was a prospective, randomized, double-blind placebo-controlled intervention trial enrolling patients with hypercholesterolemia (defined as a baseline total cholesterol ≥200 mg/dL and/or baseline low-density lipoprotein cholesterol ≥100 mg/dL). Eighty subjects were divided equally into one of four groups: (1) pterostilbene 125 mg twice daily, (2) pterostilbene 50 mg twice daily, (3) pterostilbene 50 mg + grape extract (GE) 100 mg twice daily, and (4) matching placebo twice daily for 6-8 weeks. Safety markers included biochemical and subjective measures. Linear mixed models were used to estimate primary safety measure treatment effects. Results. The majority of patients completed the trial (91.3%). The average age was 54 years. The majority of patients were females (71%) and Caucasians (70%). There were no adverse drug reactions (ADRs) on hepatic, renal, or glucose markers based on biochemical analysis. There were no statistically significant self-reported or major ADRs. Conclusion. Pterostilbene is generally safe for use in humans up to 250 mg/day.
    58. Ramírez-Garza SL et al.: Health Effects of Resveratrol: Results from Human Intervention Trials. Nutrients 2018. (PMID 30513922) [PubMed] [DOI] [Full text] The effect of resveratrol (RV) intake has been reviewed in several studies performed in humans with different health status. The purpose of this review is to summarize the results of clinical trials of the last decade, in which RV was determined in biological samples such as human plasma, urine, and feces. The topics covered include RV bioavailability, pharmacokinetics, effects on cardiovascular diseases, cognitive diseases, cancer, type 2 diabetes (T2D), oxidative stress, and inflammation states. The overview of the recent research reveals a clear tendency to identify RV in plasma, showing that its supplementation is safe. Furthermore, RV bioavailability depends on several factors such as dose, associated food matrix, or time of ingestion. Notably, enterohepatic recirculation of RV has been observed, and RV is largely excreted in the urine within the first four hours after consumption. Much of the research on RV in the last 10 years has focused on its effects on pathologies related to oxidative stress, inflammatory biomarkers, T2D, cardiovascular diseases, and neurological diseases.
    59. Li YR et al.: Effect of resveratrol and pterostilbene on aging and longevity. Biofactors 2018. (PMID 29210129) [PubMed] [DOI] Over the past years, several studies have found that foods rich in polyphenols protect against age-related disease, such as atherosclerosis, cardiovascular disease, cancer, arthritis, cataracts, osteoporosis, type 2 diabetes (T2D), hypertension and Alzheimer's disease. Resveratrol and pterostilbene, the polyphenol found in grape and blueberries, have beneficial effects as anti-aging compounds through modulating the hallmarks of aging, including oxidative damage, inflammation, telomere attrition and cell senescence. In this review, we discuss the relationship between resveratrol and pterostilbene and possible aging biomarker, including oxidative stress, inflammation, and high-calorie diets. Moreover, we also discuss the positive effect of resveratrol and pterostilbene on lifespan, aged-related disease, and health maintenance. Furthermore, we summarize a variety of important mechanisms modulated by resveratrol and pterostilbene possibly involved in attenuating age-associated disorders. Overall, we describe resveratrol and pterostilbene potential for prevention or treatment of several age-related diseases by modulating age-related mechanisms. © 2017 BioFactors, 44(1):69-82, 2018.
    60. McCormack D & McFadden D: A review of pterostilbene antioxidant activity and disease modification. Oxid Med Cell Longev 2013. (PMID 23691264) [PubMed] [DOI] [Full text] Pterostilbene (trans-3,5-dimethoxy-4-hydroxystilbene) is a natural dietary compound and the primary antioxidant component of blueberries. It has increased bioavailability in comparison to other stilbene compounds, which may enhance its dietary benefit and possibly contribute to a valuable clinical effect. Multiple studies have demonstrated the antioxidant activity of pterostilbene in both in vitro and in vivo models illustrating both preventative and therapeutic benefits. The antioxidant activity of pterostilbene has been implicated in anticarcinogenesis, modulation of neurological disease, anti-inflammation, attenuation of vascular disease, and amelioration of diabetes. In this review, we explore the antioxidant properties of pterostilbene and its relationship to common disease pathways and give a summary of the clinical potential of pterostilbene in the prevention and treatment of various medical conditions.
    61. Knutson MD & Leeuwenburgh C: Resveratrol and novel potent activators of SIRT1: effects on aging and age-related diseases. Nutr Rev 2008. (PMID 18826454) [PubMed] [DOI] Studies show that the plant polyphenol resveratrol can extend the life span of yeast, worms, flies, and fish. It also mitigates the metabolic dysfunction of mice fed high-fat diets. Resveratrol appears to mediate these effects partly by activating SIRT1, a deacetylase enzyme that regulates the activity of several transcriptional factors and enzymes responsive to nutrient availability. However, few foods contain resveratrol and humans metabolize it extensively, resulting in very low systemic bioavailability. Substantial research effort now focuses on identifying and testing more bioavailable and potent activators of SIRT1 for use as pharmacologic interventions in aging and age-related disorders.
    62. Kasiotis KM et al.: Resveratrol and related stilbenes: their anti-aging and anti-angiogenic properties. Food Chem Toxicol 2013. (PMID 23567244) [PubMed] [DOI] Dietary stilbenes comprise a class of natural compounds that display significant biological activities of medicinal interest. Among them, their antioxidant, anti-aging and anti-angiogenesic properties are well established and subjects of numerous research endeavors. This mini-review aspires to account and present the literature reports published on research concerning various natural and synthetic stilbenes, such as trans-resveratrol. Special focus was given to most recent research findings, while the mechanisms underlying their anti-aging and anti-angiogenic effects as well as the respective signaling pathways involved were also presented and discussed.
    63. Hecker A et al.: The impact of resveratrol on skin wound healing, scarring, and aging. Int Wound J 2022. (PMID 33949795) [PubMed] [DOI] [Full text] Resveratrol is a well-known antioxidant that harbours many health beneficial properties. Multiple studies associated the antioxidant, anti-inflammatory, and cell protective effects of resveratrol. These diverse effects of resveratrol are also potentially involved in cutaneous wound healing, scarring, and (photo-)aging of the skin. Hence, this review highlighted the most relevant studies involving resveratrol in wound healing, scarring, and photo-aging of the skin. A systematic review was performed and the database PubMed was searched for suitable publications. Only original articles in English that investigated the effects of resveratrol in wound healing, scarring, and (photo-)aging of the skin were analysed. The literature search yielded a total of 826 studies, but only 41 studies met the inclusion criteria. The included studies showed promising results that resveratrol might be a feasible treatment approach to support wound healing, counteract excessive scarring, and even prevent photo-aging of the skin. Resveratrol represents an interesting and promising novel therapy regime but to confirm resveratrol-associated effects, more evidence based in vitro and in vivo studies are needed.
    64. Yabluchanskiy A et al.: Matrix metalloproteinase-9: Many shades of function in cardiovascular disease. Physiology (Bethesda) 2013. (PMID 24186934) [PubMed] [DOI] [Full text] Matrix metalloproteinase (MMP)-9, one of the most widely investigated MMPs, regulates pathological remodeling processes that involve inflammation and fibrosis in cardiovascular disease. MMP-9 directly degrades extracellular matrix (ECM) proteins and activates cytokines and chemokines to regulate tissue remodeling. MMP-9 deletion or inhibition has proven overall beneficial in multiple animal models of cardiovascular disease. As such, MMP-9 expression and activity is a common end point measured. MMP-9 cell-specific overexpression, however, has also proven beneficial and highlights the fact that little information is available on the underlying mechanisms of MMP-9 function. In this review, we summarize our current understanding of MMP-9 physiology, including structure, regulation, activation, and downstream effects of increased MMP-9. We discuss MMP-9 roles during inflammation and fibrosis in cardiovascular disease. By concentrating on the substrates of MMP-9 and their roles in cardiovascular disease, we explore the overall function and discuss future directions on the translational potential of MMP-9 based therapies.
    65. Moens U et al.: The Role of Mitogen-Activated Protein Kinase-Activated Protein Kinases (MAPKAPKs) in Inflammation. Genes (Basel) 2013. (PMID 24705157) [PubMed] [DOI] [Full text] Mitogen-activated protein kinase (MAPK) pathways are implicated in several cellular processes including proliferation, differentiation, apoptosis, cell survival, cell motility, metabolism, stress response and inflammation. MAPK pathways transmit and convert a plethora of extracellular signals by three consecutive phosphorylation events involving a MAPK kinase kinase, a MAPK kinase, and a MAPK. In turn MAPKs phosphorylate substrates, including other protein kinases referred to as MAPK-activated protein kinases (MAPKAPKs). Eleven mammalian MAPKAPKs have been identified: ribosomal-S6-kinases (RSK1-4), mitogen- and stress-activated kinases (MSK1-2), MAPK-interacting kinases (MNK1-2), MAPKAPK-2 (MK2), MAPKAPK-3 (MK3), and MAPKAPK-5 (MK5). The role of these MAPKAPKs in inflammation will be reviewed.
    66. de la Lastra CA & Villegas I: Resveratrol as an anti-inflammatory and anti-aging agent: mechanisms and clinical implications. Mol Nutr Food Res 2005. (PMID 15832402) [PubMed] [DOI] Resveratrol is a phytoalexin polyphenolic compound found in various plants, including grapes, berries, and peanuts. Multiple lines of compelling evidence indicate its beneficial effects on neurological, hepatic, and cardiovascular systems. Also one of the most striking biological activities of resveratrol soundly investigated during the late years has been its cancer-chemopreventive potential. In fact, recently it has been demonstrated that this stilbene blocks the multistep process of carcinogenesis at various stages: tumor initiation, promotion, and progression. One of the possible mechanisms for its biological activities involves downregulation of the inflammatory response through inhibition of synthesis and release of pro-inflammatory mediators, modification of eicosanoid synthesis, inhibition of activated immune cells, or inhibiting such as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) via its inhibitory effects on nuclear factor (kappa)B (NF-(kappa)B) or the activator protein-1 (AP-1). More recent data provide interesting insights into the effect of this compound on the lifespan of yeast and flies, implicating the potential of resveratrol as an anti-aging agent in treating age-related human diseases. It is worthy to note that the phenolic compound possesses a low bioavailability and rapid clearance from the plasma. As the positive effects of resveratrol on inflammatory response regulation may comprise relevant clinical implications, the purpose of this article is to review its strong anti-inflammatory activity and the plausible mechanisms of these effects. Also, this review is intended to provide the reader an up-date of the bioavailability and pharmacokinetics of resveratrol and its impact on lifespan.
    67. Teng WL et al.: Pterostilbene Attenuates Particulate Matter-Induced Oxidative Stress, Inflammation and Aging in Keratinocytes. Antioxidants (Basel) 2021. (PMID 34679686) [PubMed] [DOI] [Full text] Particulate matter (PM) is the main indicator of air pollutants, and it may increase the level of reactive oxygen species (ROS) in keratinocytes, leading to skin inflammation, aging, and decreased moisturizing ability. Pterostilbene (PTS) is a dimethylated analog of resveratrol that has antioxidant effects. However, the molecular mechanisms of PTS in preventing PM-induced keratinocyte inflammation and aging have not been investigated yet. Therefore, we used PM-induced human keratinocytes to investigate the protective mechanisms of PTS. The results showed that 20 μM PTS had no toxicity to HaCaT keratinocytes and significantly reduced PM-induced intracellular ROS production. In addition, nuclear translocation of the aryl hydrocarbon receptor (AHR) was inhibited by PTS, leading to reduced expression of its downstream CYP1A1. PTS further inhibited PM-induced MAPKs, inflammation (COX-2), and aging (MMP-9) protein cascades, and rescued moisturizing (AQP-3) protein expression. We analyzed the PTS content in cells at different time points and compared the concentration required for PTS to inhibit the target proteins. Finally, we used the skin penetration assay to show that the PTS essence mainly exists in the epidermal layer and did not enter the system circulation. In conclusion, PTS could protect HaCaT keratinocytes from PM-induced damage and has the potential to become a cosmetic ingredient.
    68. Escolme SM, Wakeling LA, Alatawi F, Valentine R, Ford D. Does resveratrol act independently of SIRT1 to affect genes relevant to ageing? Proceedings of the Nutrition Society. 2013;72(OCE4):E191. [DOI]
    69. Fernández AF & Fraga MF: The effects of the dietary polyphenol resveratrol on human healthy aging and lifespan. Epigenetics 2011. (PMID 21613817) [PubMed] [DOI] The physiological effects of the dietary polyphenol resveratrol are being extensively studied. Resveratrol has been proposed to promote healthy aging and to increase lifespan primarily through the activation of the class III histone deacetylases (sirtuins). Although its positive effects are evident in yeast and mice they still have to be confirmed in humans. The molecular mechanisms involved in the processes are not fully understood because resveratrol may have other targets than sirtuins and the direct activation of sirtuins by resveratrol is under debate.
    70. Hu Y et al.: The controversial links among calorie restriction, SIRT1, and resveratrol. Free Radic Biol Med 2011. (PMID 21569839) [PubMed] [DOI] It has been widely known that slow metabolism induced by calorie restriction (CR) can extend the life span of model organisms though the underlying mechanism remains poorly understood. Accumulated evidence suggests that SIRT1 may be actively involved in CR-induced signaling pathways. As a putative activator of SIRT1, resveratrol, known for the French paradox, can partially mimic the physiological effects of CR. While the deacetylase activity of SIRT1 is important for the beneficial effects of resveratrol, resveratrol-induced SIRT1 activation has recently been challenged by the observations that resveratrol could not induce SIRT1-mediated deacetylation of native substrates in vitro. To resolve the discrepancy of resveratrol-induced activation of SIRT1 deacetylase activity between the in vitro and in vivo assays, a model of indirect SIRT1 activation by resveratrol is proposed. In this review, we will discuss the emerging roles of SIRT1 and resveratrol in CR and focus on debate over the links between SIRT1 and resveratrol.
    71. Bonkowski MS & Sinclair DA: Slowing ageing by design: the rise of NAD+ and sirtuin-activating compounds. Nat Rev Mol Cell Biol 2016. (PMID 27552971) [PubMed] [DOI] [Full text] The sirtuins (SIRT1-7) are a family of nicotinamide adenine dinucleotide (NAD+)-dependent deacylases with remarkable abilities to prevent diseases and even reverse aspects of ageing. Mice engineered to express additional copies of SIRT1 or SIRT6, or treated with sirtuin-activating compounds (STACs) such as resveratrol and SRT2104 or with NAD+ precursors, have improved organ function, physical endurance, disease resistance and longevity. Trials in non-human primates and in humans have indicated that STACs may be safe and effective in treating inflammatory and metabolic disorders, among others. These advances have demonstrated that it is possible to rationally design molecules that can alleviate multiple diseases and possibly extend lifespan in humans.
    72. Grant, R. Resveratrol Increases Intracellular NAD+ Levels Through Up regulation of The NAD+ Synthetic Enzyme Nicotinamide Mononucleotide Adenylyltransferase. Nat Prec (2010). [DOI]
    73. Simic P et al.: Nicotinamide riboside with pterostilbene (NRPT) increases NAD+ in patients with acute kidney injury (AKI): a randomized, double-blind, placebo-controlled, stepwise safety study of escalating doses of NRPT in patients with AKI. BMC Nephrol 2020. (PMID 32791973) [PubMed] [DOI] [Full text] BACKGROUND: Preclinical studies have identified both NAD+ and sirtuin augmentation as potential strategies for the prevention and treatment of AKI. Nicotinamide riboside (NR) is a NAD+ precursor vitamin and pterostilbene (PT) is potent sirtuin activator found in blueberries. Here, we tested the effect of combined NR and PT (NRPT) on whole blood NAD+ levels and safety parameters in patients with AKI. METHODS: We conducted a randomized, double-blind, placebo-controlled study of escalating doses of NRPT in 24 hospitalized patients with AKI. The study was comprised of four Steps during which NRPT (5 subjects) or placebo (1 subject) was given twice a day for 2 days. NRPT dosing was increased in each Step: Step 1250/50 mg, Step 2500/100 mg, Step 3750/150 mg and Step 41,000/200 mg. Blood NAD+ levels were measured by liquid chromatography-mass spectrometry and safety was assessed by history, physical exam, and clinical laboratory testing. RESULTS: AKI resulted in a 50% reduction in whole blood NAD+ levels at 48 h compared to 0 h in patients receiving placebo (p = 0.05). There was a trend for increase in NAD+ levels in all NRPT Steps individually at 48 h compared to 0 h, but only the change in Step 2 reached statistical significance (47%, p = 0.04), and there was considerable interindividual variability in the NAD+ response to treatment. Considering all Steps together, NRPT treatment increased NAD+ levels by 37% at 48 h compared to 0 h (p = 0.002). All safety laboratory tests were unchanged by NRPT treatment, including creatinine, estimated glomerular filtration rate (eGFR), electrolytes, liver function tests, and blood counts. Three of 20 patients receiving NRPT reported minor gastrointestinal side effects. CONCLUSION: NRPT increases whole blood NAD+ levels in hospitalized patients with AKI. In addition, NRPT up to a dose of 1000 mg/200 mg twice a day for 2 days is safe and well tolerated in these patients. Further studies to assess the potential therapeutic benefit of NRPT in AKI are warranted. TRIAL REGISTRATION: NCT03176628 , date of registration June 5th, 2017.
    74. Dellinger RW et al.: Repeat dose NRPT (nicotinamide riboside and pterostilbene) increases NAD+ levels in humans safely and sustainably: a randomized, double-blind, placebo-controlled study. NPJ Aging Mech Dis 2017. (PMID 29184669) [PubMed] [DOI] [Full text] NRPT is a combination of nicotinamide riboside (NR), a nicotinamide adenine dinucleotide (NAD+) precursor vitamin found in milk, and pterostilbene (PT), a polyphenol found in blueberries. Here, we report this first-in-humans clinical trial designed to assess the safety and efficacy of a repeat dose of NRPT (commercially known as Basis). NRPT was evaluated in a randomized, double-blind, and placebo-controlled study in a population of 120 healthy adults between the ages of 60 and 80 years. The study consisted of three treatment arms: placebo, recommended dose of NRPT (NRPT 1X), and double dose of NRPT (NRPT 2X). All subjects took their blinded supplement daily for eight weeks. Analysis of NAD+ in whole blood demonstrated that NRPT significantly increases the concentration of NAD+ in a dose-dependent manner. NAD+ levels increased by approximately 40% in the NRPT 1X group and approximately 90% in the NRPT 2X group after 4 weeks as compared to placebo and baseline. Furthermore, this significant increase in NAD+ levels was sustained throughout the entire 8-week trial. NAD+ levels did not increase for the placebo group during the trial. No serious adverse events were reported in this study. This study shows that a repeat dose of NRPT is a safe and effective way to increase NAD+ levels sustainably.
    75. Garrido-Maraver J et al.: Coenzyme q10 therapy. Mol Syndromol 2014. (PMID 25126052) [PubMed] [DOI] [Full text] For a number of years, coenzyme Q10 (CoQ10) was known for its key role in mitochondrial bioenergetics; later studies demonstrated its presence in other subcellular fractions and in blood plasma, and extensively investigated its antioxidant role. These 2 functions constitute the basis for supporting the clinical use of CoQ10. Also, at the inner mitochondrial membrane level, CoQ10 is recognized as an obligatory cofactor for the function of uncoupling proteins and a modulator of the mitochondrial transition pore. Furthermore, recent data indicate that CoQ10 affects the expression of genes involved in human cell signaling, metabolism and transport, and some of the effects of CoQ10 supplementation may be due to this property. CoQ10 deficiencies are due to autosomal recessive mutations, mitochondrial diseases, aging-related oxidative stress and carcinogenesis processes, and also statin treatment. Many neurodegenerative disorders, diabetes, cancer, and muscular and cardiovascular diseases have been associated with low CoQ10 levels as well as different ataxias and encephalomyopathies. CoQ10 treatment does not cause serious adverse effects in humans and new formulations have been developed that increase CoQ10 absorption and tissue distribution. Oral administration of CoQ10 is a frequent antioxidant strategy in many diseases that may provide a significant symptomatic benefit.
    76. Garrido-Maraver J et al.: Clinical applications of coenzyme Q10. Front Biosci (Landmark Ed) 2014. (PMID 24389208) [PubMed] [DOI] Coenzyme Q10 (CoQ10) or ubiquinone was known for its key role in mitochondrial bioenergetics as electron and proton carrier; later studies demonstrated its presence in other cellular membranes and in blood plasma, and extensively investigated its antioxidant role. These two functions constitute the basis for supporting the clinical indication of CoQ10. Furthermore, recent data indicate that CoQ10 affects expression of genes involved in human cell signalling, metabolism and transport and some of the effects of CoQ10 supplementation may be due to this property. CoQ10 deficiencies are due to autosomal recessive mutations, mitochondrial diseases, ageing-related oxidative stress and carcinogenesis processes, and also a secondary effect of statin treatment. Many neurodegenerative disorders, diabetes, cancer, fibromyalgia, muscular and cardiovascular diseases have been associated with low CoQ10 levels. CoQ10 treatment does not cause serious adverse effects in humans and new formulations have been developed that increase CoQ10 absorption and tissue distribution. Oral CoQ10 treatment is a frequent mitochondrial energizer and antioxidant strategy in many diseases that may provide a significant symptomatic benefit.
    77. Martelli A et al.: Coenzyme Q10: Clinical Applications in Cardiovascular Diseases. Antioxidants (Basel) 2020. (PMID 32331285) [PubMed] [DOI] [Full text] Coenzyme Q10 (CoQ10) is a ubiquitous factor present in cell membranes and mitochondria, both in its reduced (ubiquinol) and oxidized (ubiquinone) forms. Its levels are high in organs with high metabolism such as the heart, kidneys, and liver because it acts as an energy transfer molecule but could be reduced by aging, genetic factors, drugs (e.g., statins), cardiovascular (CV) diseases, degenerative muscle disorders, and neurodegenerative diseases. As CoQ10 is endowed with significant antioxidant and anti-inflammatory features, useful to prevent free radical-induced damage and inflammatory signaling pathway activation, its depletion results in exacerbation of inflammatory processes. Therefore, exogenous CoQ10 supplementation might be useful as an adjuvant in the treatment of cardiovascular diseases such as heart failure, atrial fibrillation, and myocardial infarction and in associated risk factors such as hypertension, insulin resistance, dyslipidemias, and obesity. This review aims to summarize the current evidences on the use of CoQ10 supplementation as a therapeutic approach in cardiovascular diseases through the analysis of its clinical impact on patients' health and quality of life. A substantial reduction of inflammatory and oxidative stress markers has been observed in several randomized clinical trials (RCTs) focused on several of the abovementioned diseases, even if more RCTs, involving a larger number of patients, will be necessary to strengthen these interesting findings.
    78. Hernández-Camacho JD et al.: Coenzyme Q10 Supplementation in Aging and Disease. Front Physiol 2018. (PMID 29459830) [PubMed] [DOI] [Full text] Coenzyme Q (CoQ) is an essential component of the mitochondrial electron transport chain and an antioxidant in plasma membranes and lipoproteins. It is endogenously produced in all cells by a highly regulated pathway that involves a mitochondrial multiprotein complex. Defects in either the structural and/or regulatory components of CoQ complex or in non-CoQ biosynthetic mitochondrial proteins can result in a decrease in CoQ concentration and/or an increase in oxidative stress. Besides CoQ10 deficiency syndrome and aging, there are chronic diseases in which lower levels of CoQ10 are detected in tissues and organs providing the hypothesis that CoQ10 supplementation could alleviate aging symptoms and/or retard the onset of these diseases. Here, we review the current knowledge of CoQ10 biosynthesis and primary CoQ10 deficiency syndrome, and have collected published results from clinical trials based on CoQ10 supplementation. There is evidence that supplementation positively affects mitochondrial deficiency syndrome and the symptoms of aging based mainly on improvements in bioenergetics. Cardiovascular disease and inflammation are alleviated by the antioxidant effect of CoQ10. There is a need for further studies and clinical trials involving a greater number of participants undergoing longer treatments in order to assess the benefits of CoQ10 treatment in metabolic syndrome and diabetes, neurodegenerative disorders, kidney diseases, and human fertility.
    79. Gutierrez-Mariscal FM et al.: Coenzyme Q10: From bench to clinic in aging diseases, a translational review. Crit Rev Food Sci Nutr 2019. (PMID 29451807) [PubMed] [DOI] Coenzyme Q10 (CoQ10) is a ubiquitous molecule present in all eukaryotic organisms whose principal role in the cell is related to its participation in the electron transport chain in the inner mitochondrial membrane. CoQ10 plays a major role in the control of cell redox status, and both the amount and functionality of this molecule have been related to the regulation of reactive oxygen species generation. Numerous reports can be found discussing the implications of CoQ10 supplementation in human studies and clinical trials related to aging. However, few reviews have made an updating through the translational point of view to integrate both basic and clinical aspects. The aim of this paper is to review our current knowledge from CoQ10 implications at biochemical and physiological level, in order to unravel the molecular mechanisms involved in its application in clinical practice. Although the importance of CoQ10 has been mainly attributed to its role as an agent for energy transduction in mitochondria, new functions for CoQ10 have been described in the recent past years, including anti-inflammatory effects, gene expression regulation and lipid bilayer membranes stabilization, which explain its involvement in aging and age-related diseases such as cardiovascular diseases, renal failure and neurodegenerative diseases.
    80. Díaz-Casado ME et al.: The Paradox of Coenzyme Q10 in Aging. Nutrients 2019. (PMID 31540029) [PubMed] [DOI] [Full text] Coenzyme Q (CoQ) is an essential endogenously synthesized molecule that links different metabolic pathways to mitochondrial energy production thanks to its location in the mitochondrial inner membrane and its redox capacity, which also provide it with the capability to work as an antioxidant. Although defects in CoQ biosynthesis in human and mouse models cause CoQ deficiency syndrome, some animals models with particular defects in the CoQ biosynthetic pathway have shown an increase in life span, a fact that has been attributed to the concept of mitohormesis. Paradoxically, CoQ levels decline in some tissues in human and rodents during aging and coenzyme Q10 (CoQ10) supplementation has shown benefits as an anti-aging agent, especially under certain conditions associated with increased oxidative stress. Also, CoQ10 has shown therapeutic benefits in aging-related disorders, particularly in cardiovascular and metabolic diseases. Thus, we discuss the paradox of health benefits due to a defect in the CoQ biosynthetic pathway or exogenous supplementation of CoQ10.
    81. González-Guardia L et al.: Effects of the Mediterranean diet supplemented with coenzyme q10 on metabolomic profiles in elderly men and women. J Gerontol A Biol Sci Med Sci 2015. (PMID 24986061) [PubMed] [DOI] BACKGROUND: Characterization of the variations in the metabolomic profiles of elderly people is a necessary step to understand changes associated with aging. This study assessed whether diets with different fat quality and supplementation with coenzyme Q10 (CoQ) affect the metabolomic profile in urine analyzed by proton nuclear magnetic resonance spectroscopy from elderly people. METHODS: Ten participants received, in a cross-over design, four isocaloric diets for 4-week periods each: Mediterranean diet supplemented with CoQ (Med + CoQ diet); Mediterranean diet; Western diet rich in saturated fat diet; low-fat, high-carbohydrate diet enriched in n-3 polyunsaturated fat. RESULTS: Multivariate analysis showed differences between diets when comparing Med + CoQ diet and saturated fat diet, with greater hippurate urine levels after Med + CoQ diet and higher phenylacetylglycine levels after saturated fat diet in women. Following consumption of Med + CoQ, hippurate excretion was positively correlated with CoQ and β-carotene plasma levels and inversely related to Nrf2, thioredoxin, superoxide dismutase 1, and gp91(phox) subunit of NADPH oxidase gene expression. After saturated fat diet consumption, phenylacetylglycine excretion was inversely related to CoQ plasma level and positively correlated with isoprostanes urinary level. CONCLUSIONS: The association between hippurate excretion and antioxidant biomarkers along with the relationship between phenylacetylglycine excretion and oxidant biomarkers suggests that the long-term consumption of a Med + CoQ diet could be beneficial for healthy aging and a promising challenge in the prevention of processes related to chronic oxidative stress, such as cardiovascular and neurodegenerative disease.
    82. Castro-Marrero J et al.: Effect of coenzyme Q10 plus nicotinamide adenine dinucleotide supplementation on maximum heart rate after exercise testing in chronic fatigue syndrome - A randomized, controlled, double-blind trial. Clin Nutr 2016. (PMID 26212172) [PubMed] [DOI] BACKGROUND & AIMS: Chronic Fatigue Syndrome (CFS) is a complex condition, characterized by severe disabling fatigue with no known cause, no established diagnostic tests, and no universally effective treatment. Several studies have proposed symptomatic treatment with coenzyme Q10 (CoQ10) and nicotinamide adenine dinucleotide (NADH) supplementation. The primary endpoint was to assess the effect of CoQ10 plus NADH supplementation on age-predicted maximum heart rate (max HR) during a cycle ergometer test. Secondary measures included fatigue, pain and sleep. METHODS: A proof-of-concept, 8-week, randomized, controlled, double-blind trial was conducted in 80 CFS patients assigned to receive either CoQ10 plus NADH supplementation or matching placebo twice daily. Maximum HR was evaluated at baseline and at end of the run-in period using an exercise test. Fatigue, pain and sleep were evaluated at baseline, and then reassessed at 4- and 8-weeks through self-reported questionnaires. RESULTS: The CoQ10 plus NADH group showed a significant reduction in max HR during a cycle ergometer test at week 8 versus baseline (P = 0.022). Perception of fatigue also showed a decrease through all follow-up visits in active group versus placebo (P = 0.03). However, pain and sleep did not improve in the active group. Coenzyme Q10 plus NADH was generally safe and well tolerated. CONCLUSIONS: Our results suggest that CoQ10 plus NADH supplementation for 8 weeks is safe and potentially effective in reducing max HR during a cycle ergometer test and also on fatigue in CFS. Further additional larger controlled trials are needed to confirm these findings. Clinical trial registrationThis trial was registered at clinicaltrials.gov as NCT02063126.
    83. Castro-Marrero J et al.: Does oral coenzyme Q10 plus NADH supplementation improve fatigue and biochemical parameters in chronic fatigue syndrome?. Antioxid Redox Signal 2015. (PMID 25386668) [PubMed] [DOI] [Full text] Chronic fatigue syndrome (CFS) is a chronic and extremely debilitating illness characterized by prolonged fatigue and multiple symptoms with unknown cause, diagnostic test, or universally effective treatment. Inflammation, oxidative stress, mitochondrial dysfunction, and CoQ10 deficiency have been well documented in CFS. We conducted an 8-week, randomized, double-blind placebo-controlled trial to evaluate the benefits of oral CoQ10 (200 mg/day) plus NADH (20 mg/day) supplementation on fatigue and biochemical parameters in 73 Spanish CFS patients. This study was registered in ClinicalTrials.gov (NCT02063126). A significant improvement of fatigue showing a reduction in fatigue impact scale total score (p<0.05) was reported in treated group versus placebo. In addition, a recovery of the biochemical parameters was also reported. NAD+/NADH (p<0.001), CoQ10 (p<0.05), ATP (p<0.05), and citrate synthase (p<0.05) were significantly higher, and lipoperoxides (p<0.05) were significantly lower in blood mononuclear cells of the treated group. These observations lead to the hypothesis that the oral CoQ10 plus NADH supplementation could confer potential therapeutic benefits on fatigue and biochemical parameters in CFS. Larger sample trials are warranted to confirm these findings.
    84. Zeisel S: Choline, Other Methyl-Donors and Epigenetics. Nutrients 2017. (PMID 28468239) [PubMed] [DOI] [Full text] Choline dietary intake varies such that many people do not achieve adequate intakes. Diet intake of choline can modulate methylation because, via betaine homocysteine methyltransferase (BHMT), this nutrient (and its metabolite, betaine) regulate the concentrations of S-adenosylhomocysteine and S-adenosylmethionine. Some of the epigenetic mechanisms that modify gene expression without modifying the genetic code depend on the methylation of DNA or of histones; and diet availability of choline and other methyl-group donors influences both of these methylations. Examples of methyl-donor mediated epigenetic effects include the changes in coat color and body weight in offspring when pregnant agouti mice are fed high choline, high methyl diets; the changes in tail kinking in offspring when pregnant Axin(Fu) mice are fed high choline, high methyl diets; the changes in Cdkn3 methylation and altered brain development that occurs in offspring when pregnant rodents are fed low choline diets. When choline metabolism is disrupted by deleting the gene Bhmt, DNA methylation is affected (especially in a region of chromosome 13), expression of specific genes is suppressed, and liver cancers develop. Better understanding of how nutrients such as choline and methyl-donors influence epigenetic programs has importance for our understanding of not only developmental abnormalities but also for understanding the origins of chronic diseases.
    85. Go EK et al.: Betaine suppresses proinflammatory signaling during aging: the involvement of nuclear factor-kappaB via nuclear factor-inducing kinase/IkappaB kinase and mitogen-activated protein kinases. J Gerontol A Biol Sci Med Sci 2005. (PMID 16282556) [PubMed] [DOI] Betaine is an important human nutrient obtained from various foods. In the present study, we assessed the anti-inflammatory effect of betaine on nuclear factor-kappaB (NF-kappaB) during aging. Sprague-Dawley (SD) rats, ages 7 and 21 months, were used in this study. The older rats were fed betaine. To elucidate the effect of betaine on oxidative stress-induced NF-kappaB and its signaling pathway at molecular levels, YPEN-1 cells were used. Results showed that betaine suppressed NF-kappaB and its related gene expressions of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), vascular cell adhesion molecule-1 (VCAM-1), and intracellular cell adhesion molecule-1 (ICAM-1) in aged kidney. Furthermore, betaine attenuated oxidative stress-induced NF-kappaB via nuclear factor-inducing kinase/IkappaB kinase (NIK/IKK) and mitogen-activated protein kinases (MAPKs) in the YPEN-1 cells. On the basis of these results, we concluded that betaine suppressed the age-related NF-kappaB activities associated with upregulated NIK/IKK and MAPKs that were induced by oxidative stress. Thus, betaine might be useful as a preventive agent against the activation of NF-kappaB induced during inflammation and aging.
    86. Zhao G et al.: Betaine in Inflammation: Mechanistic Aspects and Applications. Front Immunol 2018. (PMID 29881379) [PubMed] [DOI] [Full text] Betaine is known as trimethylglycine and is widely distributed in animals, plants, and microorganisms. Betaine is known to function physiologically as an important osmoprotectant and methyl group donor. Accumulating evidence has shown that betaine has anti-inflammatory functions in numerous diseases. Mechanistically, betaine ameliorates sulfur amino acid metabolism against oxidative stress, inhibits nuclear factor-κB activity and NLRP3 inflammasome activation, regulates energy metabolism, and mitigates endoplasmic reticulum stress and apoptosis. Consequently, betaine has beneficial actions in several human diseases, such as obesity, diabetes, cancer, and Alzheimer's disease.
    87. Sun WP et al.: Comparison of the effects of nicotinic acid and nicotinamide degradation on plasma betaine and choline levels. Clin Nutr 2017. (PMID 27567458) [PubMed] [DOI] AIM: The present study was to compare the effects of nicotinic acid and nicotinamide on the plasma methyl donors, choline and betaine. METHODS: Thirty adult subjects were randomly divided into three groups of equal size, and orally received purified water (C group), nicotinic acid (300 mg, NA group) or nicotinamide (300 mg, NM group). Plasma nicotinamide, N1-methylnicotinamide, homocysteine, betaine and choline levels before and 1.5-h and 3-h post-dosing, plasma normetanephrine and metanephrine concentrations at 3-h post-dosing, and the urinary excretion of N1-methyl-2-pyridone-5-carboxamide during the test period were examined. RESULTS: The level of 3-h plasma nicotinamide, N1-methylnicotinamide, homocysteine, the urinary excretion of N1-methyl-2-pyridone-5-carboxamide and pulse pressure (PP) in the NM group was 221%, 3972%, 61%, 1728% and 21.2% higher than that of the control group (P < 0.01, except homocysteine and PP P < 0.05), while the 3-h plasma betaine, normetanephrine and metanephrine level in the NM group was 24.4%, 9.4% and 11.7% lower (P < 0.05, except betaine P < 0.01), without significant difference in choline levels. Similar but less pronounced changes were observed in the NA group, with a lower level of 3-h plasma N1-methylnicotinamide (1.90 ± 0.20 μmol/l vs. 3.62 ± 0.27 μmol/l, P < 0.01) and homocysteine (12.85 ± 1.39 μmol/l vs. 18.08 ± 1.02 μmol/l, P < 0.05) but a higher level of betaine (27.44 ± 0.71 μmol/l vs. 23.52 ± 0.61 μmol/l, P < 0.05) than that of the NM group. CONCLUSION: The degradation of nicotinamide consumes more betaine than that of nicotinic acid at identical doses. This difference should be taken into consideration in niacin fortification.
    88. Li D et al.: Nicotinamide supplementation induces detrimental metabolic and epigenetic changes in developing rats. Br J Nutr 2013. (PMID 23768418) [PubMed] [DOI] Ecological evidence suggests that niacin (nicotinamide and nicotinic acid) fortification may be involved in the increased prevalence of obesity and type 2 diabetes, both of which are associated with insulin resistance and epigenetic changes. The purpose of the present study was to investigate nicotinamide-induced metabolic changes and their relationship with possible epigenetic changes. Male rats (5 weeks old) were fed with a basal diet (control group) or diets supplemented with 1 or 4 g/kg of nicotinamide for 8 weeks. Low-dose nicotinamide exposure increased weight gain, but high-dose one did not. The nicotinamide-treated rats had higher hepatic and renal levels of 8-hydroxy-2'-deoxyguanosine, a marker of DNA damage, and impaired glucose tolerance and insulin sensitivity when compared with the control rats. Nicotinamide supplementation increased the plasma levels of nicotinamide, N1-methylnicotinamide and choline and decreased the levels of betaine, which is associated with a decrease in global hepatic DNA methylation and uracil content in DNA. Nicotinamide had gene-specific effects on the methylation of CpG sites within the promoters and the expression of hepatic genes tested that are responsible for methyl transfer reactions (nicotinamide N-methyltransferase and DNA methyltransferase 1), for homocysteine metabolism (betaine-homocysteine S-methyltransferase, methionine synthase and cystathionine β-synthase) and for oxidative defence (catalase and tumour protein p53). It is concluded that nicotinamide-induced oxidative tissue injury, insulin resistance and disturbed methyl metabolism can lead to epigenetic changes. The present study suggests that long-term high nicotinamide intake (e.g. induced by niacin fortification) may be a risk factor for methylation- and insulin resistance-related metabolic abnormalities.
    89. Kashyap D et al.: Fisetin and Quercetin: Promising Flavonoids with Chemopreventive Potential. Biomolecules 2019. (PMID 31064104) [PubMed] [DOI] [Full text] Despite advancements in healthcare facilities for diagnosis and treatment, cancer remains the leading cause of death worldwide. As prevention is always better than cure, efficient strategies are needed in order to deal with the menace of cancer. The use of phytochemicals as adjuvant chemotherapeutic agents in heterogeneous human carcinomas like breast, colon, lung, ovary, and prostate cancers has shown an upward trend during the last decade or so. Flavonoids are well-known products of plant derivatives that are reportedly documented to be therapeutically active phytochemicals against many diseases encompassing malignancies, inflammatory disorders (cardiovascular disease, neurodegenerative disorder), and oxidative stress. The current review focuses on two key flavonols, fisetin and quercetin, known for their potential pharmacological relevance. Also, efforts have been made to bring together most of the concrete studies pertaining to the bioactive potential of fisetin and quercetin, especially in the modulation of a range of cancer signaling pathways. Further emphasis has also been made to highlight the molecular action of quercetin and fisetin so that one could explore cancer initiation pathways and progression, which could be helpful in designing effective treatment strategies.
    90. Yousefzadeh MJ et al.: Fisetin is a senotherapeutic that extends health and lifespan. EBioMedicine 2018. (PMID 30279143) [PubMed] [DOI] [Full text] BACKGROUND: Senescence is a tumor suppressor mechanism activated in stressed cells to prevent replication of damaged DNA. Senescent cells have been demonstrated to play a causal role in driving aging and age-related diseases using genetic and pharmacologic approaches. We previously demonstrated that the combination of dasatinib and the flavonoid quercetin is a potent senolytic improving numerous age-related conditions including frailty, osteoporosis and cardiovascular disease. The goal of this study was to identify flavonoids with more potent senolytic activity. METHODS: A panel of flavonoid polyphenols was screened for senolytic activity using senescent murine and human fibroblasts, driven by oxidative and genotoxic stress, respectively. The top senotherapeutic flavonoid was tested in mice modeling a progeroid syndrome carrying a p16INK4a-luciferase reporter and aged wild-type mice to determine the effects of fisetin on senescence markers, age-related histopathology, disease markers, health span and lifespan. Human adipose tissue explants were used to determine if results translated. FINDINGS: Of the 10 flavonoids tested, fisetin was the most potent senolytic. Acute or intermittent treatment of progeroid and old mice with fisetin reduced senescence markers in multiple tissues, consistent with a hit-and-run senolytic mechanism. Fisetin reduced senescence in a subset of cells in murine and human adipose tissue, demonstrating cell-type specificity. Administration of fisetin to wild-type mice late in life restored tissue homeostasis, reduced age-related pathology, and extended median and maximum lifespan. INTERPRETATION: The natural product fisetin has senotherapeutic activity in mice and in human tissues. Late life intervention was sufficient to yield a potent health benefit. These characteristics suggest the feasibility to translation to human clinical studies. FUND: NIH grants P01 AG043376 (PDR, LJN), U19 AG056278 (PDR, LJN, WLL), R24 AG047115 (WLL), R37 AG013925 (JLK), R21 AG047984 (JLK), P30 DK050456 (Adipocyte Subcore, JLK), a Glenn Foundation/American Federation for Aging Research (AFAR) BIG Award (JLK), Glenn/AFAR (LJN, CEB), the Ted Nash Long Life and Noaber Foundations (JLK), the Connor Group (JLK), Robert J. and Theresa W. Ryan (JLK), and a Minnesota Partnership Grant (AMAY-UMN#99)-P004610401-1 (JLK, EAA).
    91. Jang SY et al.: Nicotinamide-induced mitophagy: event mediated by high NAD+/NADH ratio and SIRT1 protein activation. J Biol Chem 2012. (PMID 22493485) [PubMed] [DOI] [Full text] Active autophagy coupled with rapid mitochondrial fusion and fission constitutes an important mitochondrial quality control mechanism and is critical to cellular health. In our previous studies, we found that exposure of cells to nicotinamide causes a decrease in mitochondrial content and an increase in mitochondrial membrane potential (MMP) by activating autophagy and inducing mitochondrial fragmentation. Here, we present evidence to show that the effect of nicotinamide is mediated through an increase of the [NAD(+)]/[NADH] ratio and the activation of SIRT1, an NAD(+)-dependent deacetylase that plays a role in autophagy flux. The [NAD(+)]/[NADH] ratio was inversely correlated with the mitochondrial content, and an increase in the ratio by the mobilization of the malate-aspartate shuttle resulted in autophagy activation and mitochondrial transformation from lengthy filaments to short dots. Furthermore, treatment of cells with SIRT1 activators, fisetin or SRT1720, induced similar changes in the mitochondrial content. Importantly, the activators induced mitochondrial fragmentation only when SIRT1 expression was intact. Meanwhile, MMP did not increase when the cells were treated with the activators, suggesting that the change in MMP is not induced by the mitochondrial turnover per se and that elevation of the [NAD(+)]/[NADH] ratio may activate additional mechanisms that cause MMP augmentation. Together, our results indicate that a metabolic state resulting in an elevated [NAD(+)]/[NADH] ratio can modulate mitochondrial quantity and quality via pathways that may include SIRT1-mediated mitochondrial autophagy.
    92. https://pubmed.ncbi.nlm.nih.gov/35458696/
    93. https://pubmed.ncbi.nlm.nih.gov/30069858/
    94. Escande C et al.: Flavonoid apigenin is an inhibitor of the NAD+ ase CD38: implications for cellular NAD+ metabolism, protein acetylation, and treatment of metabolic syndrome. Diabetes 2013. (PMID 23172919) [PubMed] [DOI] [Full text] Metabolic syndrome is a growing health problem worldwide. It is therefore imperative to develop new strategies to treat this pathology. In the past years, the manipulation of NAD(+) metabolism has emerged as a plausible strategy to ameliorate metabolic syndrome. In particular, an increase in cellular NAD(+) levels has beneficial effects, likely because of the activation of sirtuins. Previously, we reported that CD38 is the primary NAD(+)ase in mammals. Moreover, CD38 knockout mice have higher NAD(+) levels and are protected against obesity and metabolic syndrome. Here, we show that CD38 regulates global protein acetylation through changes in NAD(+) levels and sirtuin activity. In addition, we characterize two CD38 inhibitors: quercetin and apigenin. We show that pharmacological inhibition of CD38 results in higher intracellular NAD(+) levels and that treatment of cell cultures with apigenin decreases global acetylation as well as the acetylation of p53 and RelA-p65. Finally, apigenin administration to obese mice increases NAD(+) levels, decreases global protein acetylation, and improves several aspects of glucose and lipid homeostasis. Our results show that CD38 is a novel pharmacological target to treat metabolic diseases via NAD(+)-dependent pathways.
    95. Zhang F et al.: Quercetin modulates AMPK/SIRT1/NF-κB signaling to inhibit inflammatory/oxidative stress responses in diabetic high fat diet-induced atherosclerosis in the rat carotid artery. Exp Ther Med 2020. (PMID 33200005) [PubMed] [DOI] [Full text] Inflammation and oxidative stress serve interrelated roles in the development of atherosclerosis and other vascular diseases. Quercetin has been previously reported to exhibit numerous beneficial properties towards several metabolic conditions and cardiovascular disease. The present study aimed to evaluate the effects of quercetin on the 5'adenosine monophosphate-activated protein kinase (AMPK)/sirtuin 1 (SIRT1)/NF-κB signaling pathway and inflammatory/oxidative stress response in diabetic-induced atherosclerosis in the carotid artery of rats. Male Wistar rats were used to create a diabetes-induced atherosclerosis model by the administration of high fat diet (HFD) with streptozotocin, which lasted for 8 weeks. Control and diabetic rats received quercetin (30 mg/kg/day; orally) for the last 2 weeks of the diabetic period. Plasma lipid profile and vascular levels of oxidative stress markers, inflammatory cytokines, NF-κB signaling proteins and SIRT1 expression were evaluated using ELISA and western blotting. Quercetin treatment in HFD diabetic rats was reported to improve the lipid profile and reduce the number of atherosclerotic lesions, atherogenic index and malondialdehyde levels, whilst increasing the activity of enzymatic antioxidants in the carotid artery. Additionally, the inflammatory response was suppressed by quercetin administration, as indicated by the reduced NF-κB and IL-1β levels, and increased IL-10 levels. Furthermore, SIRT1 expression was revealed to be significantly increased in response to quercetin treatment compared with non-treated HFD rats. However, these effects of quercetin were abolished or reversed by the administration of compound-C (0.2 mg/kg), a specific AMPK blocker, in HFD rats. Therefore, quercetin may have promising potential in ameliorating atherosclerotic pathophysiology in the rat carotid artery by inhibiting oxidative stress and inflammatory responses mechanistically by modulating the AMPK/SIRT1/NF-κB signaling pathway.
    96. Buss GD et al.: The action of quercetin on the mitochondrial NADH to NAD(+) ratio in the isolated perfused rat liver. Planta Med 2005. (PMID 16395647) [PubMed] [DOI] It has been suggested that active forms of quercetin ( o-semiquinones) are able to oxidize NADH in mammalian cells. The purpose of this study was to investigate this proposition by measuring the beta-hydroxybutyrate to acetoacetate ratio as an indicator of the mitochondrial NADH/NAD (+) redox ratio in the isolated perfused rat liver. The NADH to NAD (+) ratio was reduced by quercetin; half-maximal reduction occurred at a concentration of 32.6 microM. Additionally, quercetin (25 to 300 microM) stimulated the Krebs cycle ( (14)CO (2) production) and inhibited oxygen uptake (50 to 300 microM). Low quercetin concentrations (25 microM) stimulated oxygen uptake. The results of the present work confirm the hypothesis that quercetin is able to participate in the oxidation of NADH in mammalian cells, shifting the cellular conditions to a more oxidized state (prooxidant activity). Stimulation of the Krebs cycle was probably caused by the increased NAD (+) availability whereas the decreased NADH availability and the inhibition of mitochondrial energy transduction could be the main causes for oxygen uptake inhibition.
    97. Gendrisch F et al.: Luteolin as a modulator of skin aging and inflammation. Biofactors 2021. (PMID 33368702) [PubMed] [DOI] Luteolin belongs to the group of flavonoids and can be found in flowers, herbs, vegetables and spices. It plays an important role in defending plants, for example against UV radiation by partially absorbing UVA and UVB radiation. Thus, luteolin can also decrease adverse photobiological effects in the skin by acting as a first line of defense. Furthermore, anti-oxidative and anti-inflammatory activities of luteolin were described on keratinocytes and fibroblasts as well as on several immune cells (e.g., macrophages, mast cell, neutrophils, dendritic cells and T cells). Luteolin can suppress proinflammatory mediators (e.g., IL-1β, IL-6, IL-8, IL-17, IL-22, TNF-α and COX-2) and regulate various signaling pathway (e.g., the NF-κB, JAK-STAT as well as TLR signaling pathway). In this way, luteolin modulates many inflammatory processes of the skin. The present review summarizes the recent in vitro and in vivo research on luteolin in the field of skin aging and skin cancer, wound healing as well as inflammatory skin diseases, including psoriasis, contact dermatitis and atopic dermatitis. In conclusion, luteolin might be a promising molecule for the development of topic formulations and systemic agents against inflammatory skin diseases.
    98. Kellenberger E et al.: Flavonoids as inhibitors of human CD38. Bioorg Med Chem Lett 2011. (PMID 21641214) [PubMed] [DOI] CD38 is a multifunctional enzyme which is ubiquitously distributed in mammalian tissues. It is involved in the conversion of NAD(P)(+) into cyclic ADP-ribose, NAADP(+) and ADP-ribose and the role of these metabolites in multiple Ca(2+) signaling pathways makes CD38 a novel potential pharmacological target. The dire paucity of CD38 inhibitors, however, renders the search for new molecular tools highly desirable. We report that human CD38 is inhibited at low micromolar concentrations by flavonoids such as luteolinidin, kuromanin and luteolin (IC(50) <10 μM). Docking studies provide some clues on the mode of interaction of these molecules with the active site of CD38.
    99. Boslett J et al.: Luteolinidin Protects the Postischemic Heart through CD38 Inhibition with Preservation of NAD(P)(H). J Pharmacol Exp Ther 2017. (PMID 28108596) [PubMed] [DOI] [Full text] We recently showed that ischemia/reperfusion (I/R) of the heart causes CD38 activation with resultant depletion of the cardiac NADP(H) pool, which is most marked in the endothelium. This NADP(H) depletion was shown to limit the production of nitric oxide by endothelial nitric oxide synthase (eNOS), which requires NADPH for nitric oxide production, resulting in greatly altered endothelial function. Therefore, intervention with CD38 inhibitors could reverse postischemic eNOS-mediated endothelial dysfunction. Here, we evaluated the potency of the CD38 inhibitor luteolinidin, an anthocyanidin, at blocking CD38 activity and preserving endothelial and myocardial function in the postischemic heart. Initially, we characterized luteolinidin as a CD38 inhibitor in vitro to determine its potency and mechanism of inhibition. We then tested luteolinidin in the ex vivo isolated heart model, where we determined luteolinidin uptake with aqueous and liposomal delivery methods. Optimal delivery methods were then further tested to determine the effect of luteolinidin on postischemic NAD(P)(H) and tetrahydrobiopterin levels. Finally, through nitric oxide synthase-dependent coronary flow and left ventricular functional measurements, we evaluated the efficacy of luteolinidin to protect vascular and contractile function, respectively, after I/R. With enhanced postischemic preservation of NADPH and tetrahydrobiopterin, there was a dose-dependent effect of luteolinidin on increasing recovery of endothelium-dependent vasodilatory function, as well as enhancing the recovery of left ventricular contractile function with increased myocardial salvage. Thus, luteolinidin is a potent CD38 inhibitor that protects the heart against I/R injury with preservation of eNOS function and prevention of endothelial dysfunction.
    100. Wissler Gerdes EO et al.: Strategies for late phase preclinical and early clinical trials of senolytics. Mech Ageing Dev 2021. (PMID 34699859) [PubMed] [DOI] [Full text] Cellular senescence and the hallmarks of aging contribute to age-related disease and dysfunction. The Unitary Theory of Fundamental Aging Mechanisms highlights the interdependence among the hallmarks of aging and suggests that by intervening in one fundamental aging process, most or all of the other processes could be impacted. Accumulation of senescent cells is associated with frailty, cardiovascular disease, obesity, diabetes, cognitive decline, and other age- and/or chronic disease-related disorders, suggesting that senescent cells are a target for intervention. Early preclinical data using senolytics, agents that target senescent cells, show promising results in several aging and disease models. The first in-human trials using the senolytic combination of Dasatinib and Quercetin indicated reduced senescent cell burden in adipose tissue of diabetic kidney disease patients and improved physical function in patients with idiopathic pulmonary fibrosis. Clinical trials with other senolytics, including the flavonoid Fisetin and BCL-xL inhibitors, are underway. These results from preclinical and early clinical trials illustrate the potential of senolytics to alleviate age-related dysfunction and diseases. However, multiple clinical trials across different aging and disease models are desperately needed. Parallel trials across institutions through the Translational Geroscience Network are facilitating testing to determine whether senolytics can be translated into clinical application.
    101. Farkas O et al.: Polymethoxyflavone Apigenin-Trimethylether Suppresses LPS-Induced Inflammatory Response in Nontransformed Porcine Intestinal Cell Line IPEC-J2. Oxid Med Cell Longev 2015. (PMID 26180592) [PubMed] [DOI] [Full text] The in vitro anti-inflammatory effect of apigenin and its trimethylated analogue (apigenin-trimethylether) has been investigated in order to evaluate whether these flavonoids could attenuate LPS-induced inflammation in IPEC-J2 non-transformed intestinal epithelial cells. Levels of IL-6, IL-8, TNF-α, and COX-2 mRNA were measured as a marker of inflammatory response. The extracellular H2O2 level in IPEC-J2 cells was also monitored by Amplex Red assay. Our data revealed that both compounds had significant lowering effect on the inflammatory response. Apigenin (at 25 μM) significantly decreased gene expression of IL-6 in LPS-treated cells, while apigenin-trimethylether in the same concentration did not influence IL-6 mRNA level. Both apigenin and apigenin-trimethylether reduced IL-8 gene expression significantly. TNF-α mRNA level was decreased by apigenin-trimethylether, which was not influenced by apigenin. Treatment with both flavonoids caused significant reduction in the mRNA level of COX-2, but the anti-inflammatory effect of the methylated analogue was more effective than the unmethylated one. Furthermore, both flavonoids reduced significantly the level of extracellular H2O2 compared to the control cells. In conclusion, the methylated apigenin analogue could avoid LPS-induced intestinal inflammation and it could be applied in the future as an effective anti-inflammatory compound.
    102. Ahmed SA et al.: Rationalizing the therapeutic potential of apigenin against cancer. Life Sci 2021. (PMID 33333052) [PubMed] [DOI] BACKGROUND: Despite the remarkable advances made in the diagnosis and treatment of cancer during the past couple of decades, it remains the second largest cause of mortality in the world, killing approximately 9.6 million people annually. The major challenges in the treatment of the advanced stage of this disease are the development of chemoresistance, severe adverse effects of the drugs, and high treatment cost. Therefore, the development of drugs that are safe, efficacious, and cost-effective remains a 'Holy Grail' in cancer research. However, the research over the past four decades shed light on the cancer-preventive and therapeutic potential of natural products and their underlying mechanism of action. Apigenin is one such compound, which is known to be safe and has significant potential in the prevention and therapy of this disease. AIM: To assess the literature available on the potential of apigenin and its analogs in modulating the key molecular targets leading to the prevention and treatment of different types of cancer. METHOD: A comprehensive literature search has been carried out on PubMed for obtaining information related to the sources and analogs, chemistry and biosynthesis, physicochemical properties, biological activities, bioavailability and toxicity of apigenin. KEY FINDINGS: The literature search resulted in many in vitro, in vivo and a few cohort studies that evidenced the effectiveness of apigenin and its analogs in modulating important molecular targets and signaling pathways such as PI3K/AKT/mTOR, JAK/STAT, NF-κB, MAPK/ERK, Wnt/β-catenin, etc., which play a crucial role in the development and progression of cancer. In addition, apigenin was also shown to inhibit chemoresistance and radioresistance and make cancer cells sensitive to these agents. Reports have further revealed the safety of the compound and the adaptation of nanotechnological approaches for improving its bioavailability. SIGNIFICANCE: Hence, the present review recapitulates the properties of apigenin and its pharmacological activities against different types of cancer, which warrant further investigation in clinical settings.
    103. Alam W et al.: Current Status and Future Perspectives on Therapeutic Potential of Apigenin: Focus on Metabolic-Syndrome-Dependent Organ Dysfunction. Antioxidants (Basel) 2021. (PMID 34679777) [PubMed] [DOI] [Full text] Metabolic syndrome and its associated disorders such as obesity, insulin resistance, atherosclerosis and type 2 diabetes mellitus are globally prevalent. Different molecules showing therapeutic potential are currently available for the management of metabolic syndrome, although their efficacy has often been compromised by their poor bioavailability and side effects. Studies have been carried out on medicinal plant extracts for the treatment and prevention of metabolic syndrome. In this regard, isolated pure compounds have shown promising efficacy for the management of metabolic syndrome, both in preclinical and clinical settings. Apigenin, a natural bioactive flavonoid widely present in medicinal plants, functional foods, vegetables and fruits, exerts protective effects in models of neurological disorders and cardiovascular diseases and most of these effects are attributed to its antioxidant action. Various preclinical and clinical studies carried out so far show a protective effect of apigenin against metabolic syndrome. Herein, we provide a comprehensive review on both in vitro and in vivo evidence related to the promising antioxidant role of apigenin in cardioprotection, neuroprotection and renoprotection, and to its beneficial action in metabolic-syndrome-dependent organ dysfunction. We also provide evidence on the potential of apigenin in the prevention and/or treatment of metabolic syndrome, analysing the potential and limitation of its therapeutic use.
    104. Choi WH et al.: Apigenin Ameliorates the Obesity-Induced Skeletal Muscle Atrophy by Attenuating Mitochondrial Dysfunction in the Muscle of Obese Mice. Mol Nutr Food Res 2017. (PMID 28971573) [PubMed] [DOI] SCOPE: It was investigated whether apigenin (AP) protected against skeletal muscle atrophy induced by obesity. METHODS AND RESULTS: Mice were fed a high-fat diet (HFD) for 9 weeks to induce obesity, and then were assigned to two groups; the HFD group received a high-fat diet, and the HFD+AP group received a 0.1% AP-containing HFD. After additional feeding of the experimental diet for 8 weeks, mice in the HFD group were highly obese compared with the mice in the standard diet fed mice group. The mice in the AP-treated group showed less fat pad accumulation and less inflammatory cytokines without body weight reduction. The weight of skeletal muscle in the AP group tended to increase as compared with that of the HFD group. Furthermore, AP reduced the expression of atrophic genes, including MuRF1 and Atrogin-1, but increased the exercise capacity. The mitochondrial function and mitochondrial biogenesis were enhanced by AP. In cultured C2C12 cells, AP also suppressed palmitic acid-induced muscle atrophy and mitochondrial dysfunction. In addition, AP activated AMP-activated protein kinase (AMPK) in the C2C12 and the muscle of HFD-induced obese mice. CONCLUSION: The results suggested that AP ameliorated the obesity-induced skeletal muscle atrophy by attenuating mitochondrial dysfunction.
    105. Su T et al.: Apigenin inhibits STAT3/CD36 signaling axis and reduces visceral obesity. Pharmacol Res 2020. (PMID 31877350) [PubMed] [DOI] Visceral obesity is the excess deposition of visceral fat within the abdominal cavity that surrounds vital organs. Visceral obesity is directly associated with metabolic syndrome, breast cancer and endometrial cancer. In visceral obese subjects, signal transducer and activator of the transcription 3 (STAT3) in adipocytes is constitutively active. In this study, we aimed to screen for dietary herbal compounds that possess anti-visceral obesity effect. Apigenin is abundant in fruits and vegetables. Our data show that apigenin significantly reduces body weight and visceral adipose tissue (VAT), but not subcutaneous (SAT) and epididymal adipose tissues (EAT), of the high fat diet (HFD)-induced obese mice. Mechanistic studies show that HFD increases STAT3 phosphorylation in VAT, but not in SAT and EAT. Further studies suggest that apigenin binds to non-phosphorylated STAT3, reduces STAT3 phosphorylation and transcriptional activity in VAT, and consequently reduces the expression of STAT3 target gene cluster of differentiation 36 (CD36). The reduced CD36 expression in adipocytes reduces the expression of peroxisome proliferator-activated receptor gamma (PPAR-γ) which is the critical nuclear factor in adipogenesis. Our data show that apigenin reduces CD36 and PPAR-γ expressions and inhibits adipocyte differentiation; overexpression of constitutive active STAT3 reverses the apigenin-inhibited adipogenesis. Taken together, our data suggest that apigenin inhibits adipogenesis via the STAT3/CD36 axis. Our study has delineated the mechanism of action underlying the anti-visceral obesity effect of apigenin, and provide scientific evidence to support the development of apigenin as anti-visceral obesity therapeutic agent.
    106. Clayton ZS et al.: Apigenin restores endothelial function by ameliorating oxidative stress, reverses aortic stiffening, and mitigates vascular inflammation with aging. Am J Physiol Heart Circ Physiol 2021. (PMID 34114892) [PubMed] [DOI] [Full text] We assessed the efficacy of oral supplementation with the flavanoid apigenin on arterial function during aging and identified critical mechanisms of action. Young (6 mo) and old (27 mo) C57BL/6N mice (model of arterial aging) consumed drinking water containing vehicle (0.2% carboxymethylcellulose; 10 young and 7 old) or apigenin (0.5 mg/mL in vehicle; 10 young and 9 old) for 6 wk. In vehicle-treated animals, isolated carotid artery endothelium-dependent dilation (EDD), bioassay of endothelial function, was impaired in old versus young (70% ± 9% vs. 92% ± 1%, P < 0.0001) due to reduced nitric oxide (NO) bioavailability. Old mice had greater arterial reactive oxygen species (ROS) production and oxidative stress (higher nitrotyrosine) associated with greater nicotinamide adenine dinucleotide phosphate oxidase (oxidant enzyme) and lower superoxide dismutase 1 and 2 (antioxidant enzymes); ex vivo administration of Tempol (antioxidant) restored EDD to young levels, indicating ROS-mediated suppression of EDD. Old animals also had greater aortic stiffness as indicated by higher aortic pulse wave velocity (PWV, 434 ± 9 vs. 346 ± 5 cm/s, P < 0.0001) due to greater intrinsic aortic wall stiffness associated with lower elastin levels and higher collagen, advanced glycation end products (AGEs), and proinflammatory cytokine abundance. In old mice, apigenin restored EDD (96% ± 2%) by increasing NO bioavailability, normalized arterial ROS, oxidative stress, and antioxidant expression, and abolished ROS inhibition of EDD. Moreover, apigenin prevented foam cell formation in vitro (initiating step in atherosclerosis) and mitigated age-associated aortic stiffening (PWV 373 ± 5 cm/s) by normalizing aortic intrinsic wall stiffness, collagen, elastin, AGEs, and inflammation. Thus, apigenin is a promising therapeutic for arterial aging.NEW & NOTEWORTHY Our study provides novel evidence that oral apigenin supplementation can reverse two clinically important indicators of arterial dysfunction with age, namely, vascular endothelial dysfunction and large elastic artery stiffening, and prevents foam cell formation in an established cell culture model of early atherosclerosis. Importantly, our results provide extensive insight into the biological mechanisms of apigenin action, including increased nitric oxide bioavailability, normalization of age-related increases in arterial ROS production and oxidative stress, reversal of age-associated aortic intrinsic mechanical wall stiffening and adverse remodeling of the extracellular matrix, and suppression of vascular inflammation. Given that apigenin is commercially available as a dietary supplement in humans, these preclinical findings provide the experimental basis for future translational studies assessing the potential of apigenin to treat arterial dysfunction and reduce cardiovascular disease risk with aging.
    107. Li BS et al.: Apigenin Alleviates Oxidative Stress-Induced Cellular Senescence via Modulation of the SIRT1-NAD[Formula: see text]-CD38 Axis. Am J Chin Med 2021. (PMID 34049472) [PubMed] [DOI] Oxidative stress-induced cellular senescence is now regarded as an important driving mechanism in chronic lung diseases-particularly chronic obstructive pulmonary disease (COPD). 4[Formula: see text],5,7-trihydroxyflavone (Apigenin) is a natural flavonoid product abundantly present in fruits, vegetables, and Chinese medicinal herbs. It has been known that apigenin has anti-oxidant, anti-inflammatory and liver-protecting effects. The efficacy of apigenin for lung aging, however, has not been reported. In this study, we selected the hydrogen peroxide (H2O[Formula: see text]- or doxorubicin (DOXO)-induced senescence model in WI-38 human embryonic lung fibroblast cells to determine the potential anti-aging effects of apigenin in vitro and associated molecular mechanisms. We found that apigenin reduced senescence-associated [Formula: see text]-galactosidase (SA-[Formula: see text]-gal) activity and promoted cell growth, concomitant with a decrease in levels of Acetyl (ac)-p53, p21[Formula: see text], and p16[Formula: see text] and an increase in phospho (p)-Rb. Apigenin also increased the activation ratio of silent information regulator 1 (SIRT1), nicotinamide adenine dinucleotide (NAD[Formula: see text], and NAD[Formula: see text]/NADH and inhibited cluster of differentiation 38 (CD38) activity in a concentration-dependent manner. SIRT1 inhibition by SIRT1 siRNA abolished the anti-aging effect of apigenin. In addition, CD38 inhibition by CD38 siRNA or apigenin increased the SIRT1 level and reduced H2O2-induced senescence. Our findings suggest that apigenin is a promising phytochemical for reducing the impact of senescent cells in age-related lung diseases such as COPD.
    108. Ogura Y et al.: CD38 inhibition by apigenin ameliorates mitochondrial oxidative stress through restoration of the intracellular NAD+/NADH ratio and Sirt3 activity in renal tubular cells in diabetic rats. Aging (Albany NY) 2020. (PMID 32507768) [PubMed] [DOI] [Full text] Mitochondrial oxidative stress is a significant contributor to the pathogenesis of diabetic kidney disease (DKD). We previously showed that mitochondrial oxidative stress in the kidneys of Zucker diabetic fatty rats is associated with a decreased intracellular NAD+/NADH ratio and NAD+-dependent deacetylase Sirt3 activity, and increased expression of the NAD+-degrading enzyme CD38. In this study, we used a CD38 inhibitor, apigenin, to investigate the role of CD38 in DKD. Apigenin significantly reduced renal injuries, including tubulointerstitial fibrosis, tubular cell damage, and pro-inflammatory gene expression in diabetic rats. In addition, apigenin down-regulated CD38 expression, and increased the intracellular NAD+/NADH ratio and Sirt3-mediated mitochondrial antioxidative enzyme activity in the kidneys of diabetic rats. In vitro, inhibition of CD38 activity by apigenin or CD38 knockdown increased the NAD+/NADH ratio and Sirt3 activity in renal proximal tubular HK-2 cells cultured under high-glucose conditions. Together, these results demonstrate that by inhibiting the Sirt3 activity and increasing mitochondrial oxidative stress in renal tubular cells, CD38 plays a crucial role in the pathogenesis of DKD.
    109. Sztretye M et al.: Astaxanthin: A Potential Mitochondrial-Targeted Antioxidant Treatment in Diseases and with Aging. Oxid Med Cell Longev 2019. (PMID 31814873) [PubMed] [DOI] [Full text] Oxidative stress is characterized by an imbalance between prooxidant and antioxidant species, leading to macromolecular damage and disruption of redox signaling and cellular control. It is a hallmark of various diseases including metabolic syndrome, chronic fatigue syndrome, neurodegenerative, cardiovascular, inflammatory, and age-related diseases. Several mitochondrial defects have been considered to contribute to the development of oxidative stress and known as the major mediators of the aging process and subsequent age-associated diseases. Thus, mitochondrial-targeted antioxidants should prevent or slow down these processes and prolong longevity. This is the reason why antioxidant treatments are extensively studied and newer and newer compounds with such an effect appear. Astaxanthin, a xanthophyll carotenoid, is the most abundant carotenoid in marine organisms and is one of the most powerful natural compounds with remarkable antioxidant activity. Here, we summarize its antioxidant targets, effects, and benefits in diseases and with aging.
    110. Zhang XS et al.: Astaxanthin ameliorates oxidative stress and neuronal apoptosis via SIRT1/NRF2/Prx2/ASK1/p38 after traumatic brain injury in mice. Br J Pharmacol 2021. (PMID 33326114) [PubMed] [DOI] BACKGROUND AND PURPOSE: Oxidative stress and neuronal apoptosis play key roles in traumatic brain injury. We investigated the protective effects of astaxanthin against traumatic brain injury and its underlying mechanisms of action. EXPERIMENTAL APPROACH: A weight-drop model of traumatic brain injury in vivo and hydrogen peroxide exposure in vitro model were established. Brain oedema, behaviour tests, western blot, biochemical analysis, lesion volume, histopathological study and cell viability were performed. KEY RESULTS: Astaxanthin significantly reduced oxidative insults on Days 1, 3 and 7 after traumatic brain injury. Neuronal apoptosis was also ameliorated on Day 3. Additionally, astaxanthin improved neurological functions up to 3 weeks after traumatic brain injury. Astaxanthin treatment dramatically enhanced the expression of peroxiredoxin 2 (Prx2), nuclear factor-erythroid 2-related factor 2 (NRF2/Nrf2) and sirtuin 1 (SIRT1), while it down-regulated the phosphorylation of apoptosis signal-regulating kinase 1 (ASK1) and p38. Inhibition of Prx2 by siRNA injection reversed the beneficial effects of astaxanthin against traumatic brain injury. Additionally, Nrf2 knockout prevented the neuroprotective effects of astaxanthin in traumatic brain injury. In contrast, overexpression of Prx2 in Nrf2 knockout mice attenuated the secondary brain injury after traumatic brain injury. Moreover, inhibiting SIRT1 by EX527 dramatically inhibited the neuroprotective effects of astaxanthin and suppressed SIRT1/Nrf2/Prx2/ASK1/p38 pathway both in vivo and in vitro. CONCLUSION AND IMPLICATIONS: Astaxanthin improved the neurological functions and protected the brain from injury after traumatic brain injury, primarily by reducing oxidative stress and neuronal death via SIRT1/Nrf2/Prx2/ASK1/p38 signalling pathway and might be a new candidate to ameliorate traumatic brain injury.
    111. Zhang J et al.: Astaxanthin attenuated pressure overload-induced cardiac dysfunction and myocardial fibrosis: Partially by activating SIRT1. Biochim Biophys Acta Gen Subj 2017. (PMID 28300638) [PubMed] [DOI] BACKGROUND: Myocardial fibrosis contributes to cardiac dysfunction. Astaxanthin (AST), a member of the carotenoid family, is a well-known antioxidant, but its effect on and underlying mechanisms in myocardial fibrosis are poorly understood. METHODS: In vivo, myocardial fibrosis and cardiac dysfunction were induced using transverse aortic constriction (TAC). AST was administered to mice for 12weeks post-surgery. In vitro, transforming growth factor β1 (TGF-β1) was used to stimulate human cardiac fibroblasts (HCFs). EX-527 (6-chloro-2, 3, 4, 9-tetrahydro-1H-carbazole-1-carboxamide) and SIRT1 siRNA were used to inhibit SIRT1 in vivo and in vitro, respectively. The effects of AST on cardiac function and fibrosis were determined. SIRT1 expression and activity were measured to explore the mechanisms underlying its effects. RESULTS: AST improved cardiac function and attenuated fibrosis. Receptor activated-SMADs (R-SMADs), including SMAD2 and SMAD3, played important roles in these processes. The TAC surgery-induced increases in the expression of phosphorylated and acetylated R-SMADs were attenuated by treatment with AST, the translocation and transcriptional activity of R-SMADs were also restrained. These effects were accompanied by an increase in the expression and activity of SIRT1. Inhibiting SIRT1 attenuated the acetylation and transcriptional activity of R-SMADs, but not their phosphorylation and translocation. CONCLUSIONS: Our data demonstrate that AST improves cardiac function and attenuates fibrosis by decreasing phosphorylation and deacetylation of R-SMADs. SIRT1 contributes to AST's protective function by reducing acetylation of R-SMADs. GENERAL SIGNIFICANCE: These data suggest that AST may be useful as a preventive/therapeutic agent for cardiac dysfunction and myocardial fibrosis.
    112. Shatoor AS & Al Humayed S: Astaxanthin Ameliorates high-fat diet-induced cardiac damage and fibrosis by upregulating and activating SIRT1. Saudi J Biol Sci 2021. (PMID 34867002) [PubMed] [DOI] [Full text] This study evaluated the protective effect of astaxanthin (ASX) against high-fat diet (HFD)-induced cardiac damage and fibrosis in rats and examined if the mechanism of protection involves modulating SIRT1. Rat were divided into 5 groups (n = 10/group) as: 1) control: fed normal diet (3.82 kcal/g), 2) control + ASX (200 mg/kg/orally), 3) HFD: fed HFD (4.7 kcal/g), 4) HFD + ASX (200 mg/kg/orally), and HFD + ASX + EX-527 (1 mg/kg/i.p) (a selective SIRT1 inhibitor). All treatments were conducted for 14 weeks. Administration of ASX reduced cardiomyocyte damage, inhibited inflammatory cell infiltration, preserved cardiac fibers structure, prevented collagen deposition and protein levels of TGF-β 1 in the left ventricles (LVs) of HFD-fed rats. In the LVs of both the control and HFD-fed rat, ASX significantly reduced levels of reactive oxygen species (ROS), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and p-smad2/3 (Lys19) but increased the levels of glutathione (GSH), catalase, and manganese superoxide dismutase (MnSOD). Concomitantly, it increased the nuclear activity of Nrf2 and reduced that of NF-κB p65. Furthermore, administration of ASX to both the control and HFD-fed rats increased total and nuclear levels of SIRT1, stimulated the nuclear activity of SIRT1, and reduced the acetylation of Nrf2, NF-κB p65, and Smad3. All these cardiac beneficial effects of ASX in the HFD-fed rats were abolished by co-administration of EX-527. In conclusion, ASX stimulates antioxidants and inhibits markers of inflammation under basal and HFD conditions. The mechanism of protection involves, at least, activation SIRT1 signaling.
    113. Gao D et al.: Protective effect of astaxanthin against contrast-induced acute kidney injury via SIRT1-p53 pathway in rats. Int Urol Nephrol 2019. (PMID 30456546) [PubMed] [DOI] PURPOSE: The present study was designed to further investigate the protective effect of astaxanthin (AST) on contrast-induced acute kidney injury (CI-AKI) in rats and the relationship between SIRT1-p53 pathway and astaxanthin. METHODS: 40 adult male Sprague Dawley (SD) rats were randomly divided into five groups (n = 8/group): control (CON), normal rats treated with AST (AST), CM-treated (CM), CM rats treated with isoform of nitric oxide synthase (iNOS) inhibitor (iNOS + CM), and CM rats treated with AST (AST + CM). Serum creatinine (Scr) and blood urea nitrogen (BUN) values were measured at 72 h following the procedure. Hematoxylin and eosin (H-E) staining was used to observe the pathologic changes of kidney. Tunel staining was used to test apoptosis of kidney tubules. Oxidative stress, SIRT1 activity, nitric oxide (NO), and 3-nitrotyrosine (3-NT) content were individually measured with the commercial available kits. RESULTS: Compared with the CON group, Scr and BUN levels significantly increased in the CM group (P < 0.05), and the values in two pre-treatment groups (iNOS + CM and AST + CM) had significantly decreased (P < 0.05). H-E and Tunel staining had shown that renal tubular injury was severe in CM group. The renal injury score and apoptosis index in the two pre-treatment groups also decreased (P < 0.05). The present study showed that in CM group the levels of oxidative stress indicators significantly increased, and the activities of antioxidant stress indicators significantly decreased. These indicators in two pre-treatment groups significantly improved (P < 0.05). In the CM group the expression levels of SITR1 significantly increased, and the ac-p53/p53 significantly increased (P < 0.05). Compared with the CM group, in AST + CM group the expression levels of SIRT1 increased, the expression levels of p53 and ac-p53/p53 decreased (P < 0.05).The levels of NO and 3-NT in CM group significantly increased (P < 0.05). Compared the CM group, the levels in the two pre-treatment groups significantly decreased (P < 0.05). CONCLUSIONS: Astaxanthin has a protective effect on CI-AKI, the mechanism may be related to the SIRT1-p53 pathway. Astaxanthin can reduce the content of NO and 3-NT in renal tissue of CI-AKI, and alleviate the renal injury induced by contrast agents.
    114. Petyaev IM: Lycopene Deficiency in Ageing and Cardiovascular Disease. Oxid Med Cell Longev 2016. (PMID 26881023) [PubMed] [DOI] [Full text] Lycopene is a hydrocarbon phytochemical belonging to the tetraterpene carotenoid family and is found in red fruit and vegetables. Eleven conjugated double bonds predetermine the antioxidant properties of lycopene and its ability to scavenge lipid peroxyl radicals, reactive oxygen species, and nitric oxide. Lycopene has a low bioavailability rate and appears in the blood circulation incorporated into chylomicrons and other apo-B containing lipoproteins. The recent body of evidence suggests that plasma concentration of lycopene is not only a function of intestinal absorption rate but also lycopene breakdown via enzymatic and oxidative pathways in blood and tissues. Oxidative stress and the accumulation of reactive oxygen species and nitric oxide may represent a major cause of lycopene depletion in ageing, cardiovascular disease, and type 2 diabetes mellitus. It has been shown recently that low carotenoid levels, and especially decreased serum lycopene levels, are strongly predictive of all-cause mortality and poor outcomes of cardiovascular disease. However, there is a poor statistical association between dietary and serum lycopene levels which occurs due to limited bioavailability of lycopene from dietary sources. Hence, it is very unlikely that nutritional intervention alone could be instrumental in the correction of lycopene and carotenoid deficiency. Therefore, new nutraceutical formulations of carotenoids with enhanced bioavailability are urgently needed.
    115. Li J et al.: Lycopene ameliorates insulin resistance and increases muscle capillary density in aging via activation of SIRT1. J Nutr Biochem 2022. (PMID 34530111) [PubMed] [DOI] Lycopene (Ly) is a kind of hydrocarbon, which belongs to the family of tetraterpene carotene and exists in red fruits and vegetables. The decrease of capillary density and blood flow with age is a significant reason for the increase of mortality and morbidity. Herein, our study aims to explore the effects of Ly (a bioactive food compound) on vascular aging in vitro and in vivo and its potential mechanisms. The cytological results showed that Ly could promote the proliferation of human umbilical vein endothelial cell (HUVECs) and enhance the ability of HUVECs to form capillary-like structures. Furthermore, the expression of SIRT1 in aged HUVECs was up-regulated. In vivo, aging rats showed signs of insulin resistance and blood vessel damage. Additionally, the capillary density and blood flow were reduced during the vascular aging process in both D-gal-induced and naturally aging muscle. However, when Ly was given, these conditions could be reversed. Simultaneously, the contents of ATP, lactic acid and pyruvic acid were determined, and it was found that Ly could promote angiogenesis by increasing the utilization rate of glucose and promoting energy metabolism. Finally, in the insulin resistance cell model, we knocked down the SIRT1 and administrated with Ly, and found that it couldn't restore insulin transdution. In conclusion, all the data in this study demonstrate that Ly could reactivate SIRT1 and improve insulin resistance, which was a reversible cause of vascular aging.
    116. Liu X et al.: The combination of nicotinamide mononucleotide and lycopene prevents cognitive impairment and attenuates oxidative damage in D-galactose induced aging models via Keap1-Nrf2 signaling. Gene 2022. (PMID 35183682) [PubMed] [DOI] Aging is referred to progressive dysfunction of body organs, including the brain. This study aims to explore the anti-aging effect of combing nicotinamide mononucleotide (NMN) and lycopene (Lyco) (NMN + Lyco) on aging rats and senescent PC12 cells. Both in vivo and in vitro aging models were established using D-galactose (D-gal). The combination showed a trend to superiority over monotherapy in preventing aging in vivo and in vitro. Morris water maze test showed that NMN + Lyco effectively improved the ability of spatial location learning and memory of aging model rats. NMN + Lyco mitigated the oxidative stress of rat brains, livers, and PC12 cells by elevating the levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), GSH, as well as total antioxidant capacity (T-AOC), and reducing malondialdehyde (MDA) content. CCK-8 assay, senescence-associated β-galactosidase staining, and flow cytometer confirmed the cellular senescence of PC12 cells after exposing D-gal, and indicated the anti-senescence effect of NMN + Lyco in vitro. Moreover, NMN + Lyco effectively down-regulated the expressions of p53, p21, and p16 (senescence-related genes), and activated Keap1-Nrf2 signaling in both in vivo and in vitro aging models. In total, NMN + Lyco protected rats and PC12 cells from cognitive impairment and cellular senescence induced by D-gal, of which effects might be linked to the reduction of oxidative stress and the activation of Keap1-Nrf2 signaling.
    117. Bielak-Zmijewska A et al.: The Role of Curcumin in the Modulation of Ageing. Int J Mol Sci 2019. (PMID 30871021) [PubMed] [DOI] [Full text] It is believed that postponing ageing is more effective and less expensive than the treatment of particular age-related diseases. Compounds which could delay symptoms of ageing, especially natural products present in a daily diet, are intensively studied. One of them is curcumin. It causes the elongation of the lifespan of model organisms, alleviates ageing symptoms and postpones the progression of age-related diseases in which cellular senescence is directly involved. It has been demonstrated that the elimination of senescent cells significantly improves the quality of life of mice. There is a continuous search for compounds, named senolytic drugs, that selectively eliminate senescent cells from organisms. In this paper, we endeavor to review the current knowledge about the anti-ageing role of curcumin and discuss its senolytic potential.
    118. 118.0 118.1 Zendedel E et al.: Impact of curcumin on sirtuins: A review. J Cell Biochem 2018. (PMID 30145851) [PubMed] [DOI] Curcumin is a bioactive phytochemical that modulates several physiological and cellular processes leading to therapeutic effects against different diseases. Sirtuins are highly conserved nicotine adenine dinucleotide-dependent proteins that regulate the activity of target enzymes and transcription factors by deacetylation. Curcumin possesses both antioxidant and anti-inflammatory properties and has been shown to increase sirtuin-1 (SIRT1) by activating small molecules. Upregulation of SIRT1 by curcumin has been reported to confer protective effects against a range of neurological disorders including glutamate excitotoxicity, β-amyloid-induced cell death in cortical neurons, cerebral ischemic damage, and stroke. Activation of AMPK and SIRT1 by curcumin has also been noted to mediate the protective effects of curcumin against ischemia/reperfusion injury, cardiac fibrosis, diabetes, and lipid metabolism abnormalities. These protective effects of SIRT1 activation are partly mediated by the deacetylation of p53 and reduction of apoptosis. In this review, we summarize the role of SIRT1 in mediating the pharmacological effects of curcumin in several diseases.
    119. Hu A et al.: Curcumin as therapeutics for the treatment of head and neck squamous cell carcinoma by activating SIRT1. Sci Rep 2015. (PMID 26299580) [PubMed] [DOI] [Full text] SIRT1 is one of seven mammalian homologs of Sir2 that catalyzes NAD(+)-dependent protein deacetylation. The aim of the present study is to explore the effect of SIRT1 small molecule activator on the anticancer activity and the underlying mechanism. We examined the anticancer activity of a novel oral agent, curcumin, which is the principal active ingredient of the traditional Chinese herb Curcuma Longa. Treatment of FaDu and Cal27 cells with curcumin inhibited growth and induced apoptosis. Mechanistic studies showed that anticancer activity of curcumin is associated with decrease in migration of HNSCC and associated angiogenesis through activating of intrinsic apoptotic pathway (caspase-9) and extrinsic apoptotic pathway (caspase-8). Our data demonstrating that anticancer activity of curcumin is linked to the activation of the ATM/CHK2 pathway and the inhibition of nuclear factor-κB. Finally, increasing SIRT1 through small molecule activator curcumin has shown beneficial effects in xenograft mouse model, indicating that SIRT1 may represent an attractive therapeutic target. Our studies provide the preclinical rationale for novel therapeutics targeting SIRT1 in HNSCC.
    120. Bańkowski S et al.: Effect of 6-week curcumin supplementation on aerobic capacity, antioxidant status and sirtuin 3 level in middle-aged amateur long-distance runners. Redox Rep 2022. (PMID 36125053) [PubMed] [DOI] [Full text] BACKGROUND: The study was undertaken to evaluate the effect of 6-week supplementation with a daily dose of 2g of curcumin on VO2max and prooxidant/antioxidant homeostasis in middle-aged amateur long-distance runners during the preparatory period of the macrocycle. METHODS: Thirty runners were randomly assigned to a placebo group (PL) and a curcumin-supplemented group (CU). Their VO2max was assessed before supplementation and after 6 weeks of supplementation. Venous blood samples were collected from the participants at rest, immediately after exercise, and after 1h of recovery to evaluate the activity of antioxidant enzymes (SOD, CAT, GPx), non-enzymatic antioxidants (GSH, UA) and sirtuin 3 level (SIRT 3), as well as the levels of oxidative stress markers (TOS/TOC, MDA, and 8-OHdG) and muscle damage markers (CK, LDH, and Mb). RESULTS: VO2max, the activity of enzymatic antioxidants, the concentrations of non-enzymatic antioxidants, the levels of oxidative stress markers, and the levels of muscle damage markers did not change significantly in the CU group over 6 weeks of supplementation with curcumin. However, the resting concentration of SIRT 3 was found to be significantly higher (p ≤ 0.05) compared with pre-supplementation. CONCLUSION: Curcumin supplementation does not have a significant effect on VO2max and prooxidant/antioxidant homeostasis in runners.
    121. Rhoads TW & Anderson RM: Alpha-Ketoglutarate, the Metabolite that Regulates Aging in Mice. Cell Metab 2020. (PMID 32877686) [PubMed] [DOI] [Full text] In this issue of Cell Metabolism, Asadi Shahmirzadi et al. (2020) demonstrate that late-onset dietary supplementation with calcium alpha-ketoglutarate results in increased survival, compressed morbidity, and reduced frailty in mice. The study provides further evidence for critical links between metabolism, inflammation, and aging.
    122. Chin RM et al.: The metabolite α-ketoglutarate extends lifespan by inhibiting ATP synthase and TOR. Nature 2014. (PMID 24828042) [PubMed] [DOI] [Full text] Metabolism and ageing are intimately linked. Compared with ad libitum feeding, dietary restriction consistently extends lifespan and delays age-related diseases in evolutionarily diverse organisms. Similar conditions of nutrient limitation and genetic or pharmacological perturbations of nutrient or energy metabolism also have longevity benefits. Recently, several metabolites have been identified that modulate ageing; however, the molecular mechanisms underlying this are largely undefined. Here we show that α-ketoglutarate (α-KG), a tricarboxylic acid cycle intermediate, extends the lifespan of adult Caenorhabditis elegans. ATP synthase subunit β is identified as a novel binding protein of α-KG using a small-molecule target identification strategy termed drug affinity responsive target stability (DARTS). The ATP synthase, also known as complex V of the mitochondrial electron transport chain, is the main cellular energy-generating machinery and is highly conserved throughout evolution. Although complete loss of mitochondrial function is detrimental, partial suppression of the electron transport chain has been shown to extend C. elegans lifespan. We show that α-KG inhibits ATP synthase and, similar to ATP synthase knockdown, inhibition by α-KG leads to reduced ATP content, decreased oxygen consumption, and increased autophagy in both C. elegans and mammalian cells. We provide evidence that the lifespan increase by α-KG requires ATP synthase subunit β and is dependent on target of rapamycin (TOR) downstream. Endogenous α-KG levels are increased on starvation and α-KG does not extend the lifespan of dietary-restricted animals, indicating that α-KG is a key metabolite that mediates longevity by dietary restriction. Our analyses uncover new molecular links between a common metabolite, a universal cellular energy generator and dietary restriction in the regulation of organismal lifespan, thus suggesting new strategies for the prevention and treatment of ageing and age-related diseases.
    123. Bayliak MM & Lushchak VI: Pleiotropic effects of alpha-ketoglutarate as a potential anti-ageing agent. Ageing Res Rev 2021. (PMID 33340716) [PubMed] [DOI] An intermediate of tricarboxylic acid cycle alpha-ketoglutarate (AKG) is involved in pleiotropic metabolic and regulatory pathways in the cell, including energy production, biosynthesis of certain amino acids, collagen biosynthesis, epigenetic regulation of gene expression, regulation of redox homeostasis, and detoxification of hazardous substances. Recently, AKG supplement was found to extend lifespan and delay the onset of age-associated decline in experimental models such as nematodes, fruit flies, yeasts, and mice. This review summarizes current knowledge on metabolic and regulatory functions of AKG and its potential anti-ageing effects. Impact on epigenetic regulation of ageing via being an obligate substrate of DNA and histone demethylases, direct antioxidant properties, and function as mimetic of caloric restriction and hormesis-induced agent are among proposed mechanisms of AKG geroprotective action. Due to influence on mitochondrial respiration, AKG can stimulate production of reactive oxygen species (ROS) by mitochondria. According to hormesis hypothesis, moderate stimulation of ROS production could have rather beneficial biological effects, than detrimental ones, because of the induction of defensive mechanisms that improve resistance to stressors and age-related diseases and slow down functional senescence. Discrepancies found in different models and limitations of AKG as a geroprotective drug are discussed.
    124. Demidenko O et al.: Rejuvant®, a potential life-extending compound formulation with alpha-ketoglutarate and vitamins, conferred an average 8 year reduction in biological aging, after an average of 7 months of use, in the TruAge DNA methylation test. Aging (Albany NY) 2021. (PMID 34847066) [PubMed] [DOI] [Full text] The search continues for possible interventions that delay and/or reverse biological aging, resulting in extended healthspan and lifespan. Interventions delaying aging in animal models are well established; however, most lack validation in humans. The length of human lifespan makes it impractical to perform survival analysis. Instead, aging biomarkers, such as DNA methylation (DNAm) clocks, have been developed to monitor biological age. Herein we report a retrospective analysis of DNA methylation age in 42 individuals taking Rejuvant®, an alpha-ketoglutarate based formulation, for an average period of 7 months. DNAm testing was performed at baseline and by the end of treatment with Rejuvant® supplementation. Remarkably, individuals showed an average decrease in biological aging of 8 years (p-value=6.538x10-12). Furthermore, the supplementation with Rejuvant® is robust to individual differences, as indicated by the fact that a large majority of participants decreased their biological age. Moreover, we found that Rejuvant® is of additional benefit to chronologically and biologically older individuals. While continued testing, particularly in a placebo-controlled design, is required, the nearly 8-year reversal in the biological age of individuals taking Rejuvant® for 4 to 10 months is noteworthy, making the natural product cocktail an intriguing candidate to affect human aging.
    125. Asadi Shahmirzadi A et al.: Alpha-Ketoglutarate, an Endogenous Metabolite, Extends Lifespan and Compresses Morbidity in Aging Mice. Cell Metab 2020. (PMID 32877690) [PubMed] [DOI] [Full text] Metabolism and aging are tightly connected. Alpha-ketoglutarate is a key metabolite in the tricarboxylic acid (TCA) cycle, and its levels change upon fasting, exercise, and aging. Here, we investigate the effect of alpha-ketoglutarate (delivered in the form of a calcium salt, CaAKG) on healthspan and lifespan in C57BL/6 mice. To probe the relationship between healthspan and lifespan extension in mammals, we performed a series of longitudinal, clinically relevant measurements. We find that CaAKG promotes a longer, healthier life associated with a decrease in levels of systemic inflammatory cytokines. We propose that induction of IL-10 by dietary AKG suppresses chronic inflammation, leading to health benefits. By simultaneously reducing frailty and enhancing longevity, AKG, at least in the murine model, results in a compression of morbidity.
    126. Payne A et al.: Epigallocatechin-3-Gallate (EGCG): New Therapeutic Perspectives for Neuroprotection, Aging, and Neuroinflammation for the Modern Age. Biomolecules 2022. (PMID 35327563) [PubMed] [DOI] [Full text] Alzheimer's and Parkinson's diseases are the two most common forms of neurodegenerative diseases. The exact etiology of these disorders is not well known; however, environmental, molecular, and genetic influences play a major role in the pathogenesis of these diseases. Using Alzheimer's disease (AD) as the archetype, the pathological findings include the aggregation of Amyloid Beta (Aβ) peptides, mitochondrial dysfunction, synaptic degradation caused by inflammation, elevated reactive oxygen species (ROS), and cerebrovascular dysregulation. This review highlights the neuroinflammatory and neuroprotective role of epigallocatechin-3-gallate (EGCG): the medicinal component of green tea, a known nutraceutical that has shown promise in modulating AD progression due to its antioxidant, anti-inflammatory, and anti-aging abilities. This report also re-examines the current literature and provides innovative approaches for EGCG to be used as a preventive measure to alleviate AD and other neurodegenerative disorders.
    127. Niu Y et al.: The phytochemical, EGCG, extends lifespan by reducing liver and kidney function damage and improving age-associated inflammation and oxidative stress in healthy rats. Aging Cell 2013. (PMID 23834676) [PubMed] [DOI] It is known that phytochemicals have many potential health benefits in humans. The aim of this study was to investigate the effects of long-term consumption of the phytochemical, epigallocatechin gallate (EGCG), on body growth, disease protection, and lifespan in healthy rats. 68 male weaning Wistar rats were randomly divided into the control and EGCG groups. Variables influencing lifespan such as blood pressure, serum glucose and lipids, inflammation, and oxidative stress were dynamically determined from weaning to death. The median lifespan of controls was 92.5 weeks. EGCG increased median lifespan to 105.0 weeks and delayed death by approximately 8-12 weeks. Blood pressure and serum glucose and lipids significantly increased with age in both groups compared with the levels at 0 week. However, there were no differences in these variables between the two groups during the whole lifespan. Inflammation and oxidative stress significantly increased with age in both groups compared with 0 week and were significantly lower in serum and liver and kidney tissues in the EGCG group. Damage to liver and kidney function was significantly alleviated in the EGCG group. In addition, EGCG decreased the mRNA and protein expressions of transcription factor NF-κB and increased the upstream protein expressions of silent mating type information regulation two homolog one (SIRT1) and forkhead box class O 3a (FOXO3a). In conclusion, EGCG extends lifespan in healthy rats by reducing liver and kidney damage and improving age-associated inflammation and oxidative stress through the inhibition of NF-κB signaling by activating the longevity factors FoxO3a and SIRT1.
    128. Pai PY et al.: Epigallocatechin Gallate Reduces Homocysteine-Caused Oxidative Damages through Modulation SIRT1/AMPK Pathway in Endothelial Cells. Am J Chin Med 2021. (PMID 33371812) [PubMed] [DOI] Elevated plasma concentration of total homocysteine is a pathological condition that causes vascular endothelial injury and subsequently leads to the progression of endothelial apoptosis in atherosclerosis. Epigallocatechin gallate (EGCG), a well-known anti-oxidant in green tea, has been reported with benefits on metabolic and cardiovascular diseases. This study aimed to explore that EGCG ameliorates homocysteine-induced endothelial cell apoptosis through enhancing the sirtuin 1 (SIRT1)/AMP-activated protein kinase (AMPK) survival signaling pathway. Human umbilical endothelial cells were treated with homocysteine in the presence or absence of EGCG. We found that EGCG significantly increased the activities of SIRT1 and AMPK. EGCG diminished homocysteine-mediated nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation by inhibiting protein kinase C activation as well as reactive oxygen species (ROS) generation and recovered the activity of the endogenous antioxidant enzyme, superoxidase dismutase (SOD). Besides, EGCG also restores homocysteine-mediated dephosphorylation of Akt and decreases endothelial NO synthase (eNOS) expression. Furthermore, EGCG ameliorates homocysteine-activated pro-apoptotic events. The present study shows that EGCG prevents homocysteine-induced endothelial cell apoptosis via enhancing SIRT1/AMPK as well as Akt/eNOS signaling pathways. Results from this study indicated that EGCG might have some benefits for hyperhomocysteinemia.
    129. Ayissi VB et al.: Epigenetic effects of natural polyphenols: a focus on SIRT1-mediated mechanisms. Mol Nutr Food Res 2014. (PMID 23881751) [PubMed] [DOI] Polyphenols are a class of natural compounds widely distributed in fruits, vegetables, and plants. They have been reported to possess a wide range of activities in prevention and alleviation of various diseases like cancer, neuroinflammation, diabetes, and aging. Polyphenols are effective against chronic diseases and recent reports indicated strong epigenetic effects of polyphenols. Most of the studies investigating epigenetic effects of natural polyphenols have focused on their beneficial effects in cancer treatment. However, epigenetic defects have been demonstrated in many other diseases as well, and application of polyphenols to modulate the epigenome is becoming an interesting field of research. This review summarizes the effects of natural polyphenols in modulating epigenetic-related enzymes as well as their effect in prevention and treatment of chronic diseases with a focus on SIRT1 modulation. We have also discussed the relation between the structure and function of epigenetic-modifying polyphenols.
    130. Jiang S et al.: EGCG Inhibits Proliferation and Induces Apoptosis Through Downregulation of SIRT1 in Nasopharyngeal Carcinoma Cells. Front Nutr 2022. (PMID 35548580) [PubMed] [DOI] [Full text] Epigallocatechin-3-gallate (EGCG), a frequently studied catechin in green tea, has been shown involved in the anti-proliferation and apoptosis of human nasopharyngeal carcinoma (NPC) cells. However, the underlying molecular mechanism of the apoptotic effects of EGCG has not been fully investigated. Recent literature emphasized the importance of Sirtuin 1 (SIRT1), an NAD+-dependent protein deacetylase, in regulating cellular stress responses, survival, and organismal lifespan. Herein, the study showed that EGCG could significantly inhibit cell proliferation and promote apoptosis of 2 NPC (CNE-2 and 5-8F) cell lines. Moreover, it was also found that SIRT1 is down-regulated by EGCG, and the SIRT1-p53 signaling pathway participates in the effects of EGCG on CNE-2 and 5-8 F cells. Taken together, the findings of this study provided evidence that EGCG could inhibit the growth of NPC cell lines and is linked with the inhibition of the SIRT1-p53 signaling pathway, suggesting the therapeutic potential of EGCG in human NPC.
    131. Irie J et al.: Effect of oral administration of nicotinamide mononucleotide on clinical parameters and nicotinamide metabolite levels in healthy Japanese men. Endocr J 2020. (PMID 31685720) [PubMed] [DOI] Recent studies have revealed that decline in cellular nicotinamide adenine dinucleotide (NAD+) levels causes aging-related disorders and therapeutic approaches increasing cellular NAD+ prevent these disorders in animal models. The administration of nicotinamide mononucleotide (NMN) has been shown to mitigate aging-related dysfunctions. However, the safety of NMN in humans have remained unclear. We, therefore, conducted a clinical trial to investigate the safety of single NMN administration in 10 healthy men. A single-arm non-randomized intervention was conducted by single oral administration of 100, 250, and 500 mg NMN. Clinical findings and parameters, and the pharmacokinetics of NMN metabolites were investigated for 5 h after each intervention. Ophthalmic examination and sleep quality assessment were also conducted before and after the intervention. The single oral administrations of NMN did not cause any significant clinical symptoms or changes in heart rate, blood pressure, oxygen saturation, and body temperature. Laboratory analysis results did not show significant changes, except for increases in serum bilirubin levels and decreases in serum creatinine, chloride, and blood glucose levels within the normal ranges, independent of the dose of NMN. Results of ophthalmic examination and sleep quality score showed no differences before and after the intervention. Plasma concentrations of N-methyl-2-pyridone-5-carboxamide and N-methyl-4-pyridone-5-carboxamide were significantly increased dose-dependently by NMN administration. The single oral administration of NMN was safe and effectively metabolized in healthy men without causing any significant deleterious effects. Thus, the oral administration of NMN was found to be feasible, implicating a potential therapeutic strategy to mitigate aging-related disorders in humans.
    132. Fukamizu Y et al.: Safety evaluation of β-nicotinamide mononucleotide oral administration in healthy adult men and women. Sci Rep 2022. (PMID 36002548) [PubMed] [DOI] [Full text] A decrease in the intracellular level of nicotinamide adenine dinucleotide (NAD+), an essential coenzyme for metabolic activity, causes various age-related diseases and metabolic abnormalities. Both in-vivo and in-vitro studies have shown that increasing certain NAD+ levels in cell or tissue by supplementing nicotinamide mononucleotide (NMN), a precursor of NAD+, alleviates age-related diseases and metabolic disorders. In recent years, several clinical trials have been performed to elucidate NMN efficacy in humans. However, previous clinical studies with NMN have not reported on the safety of repeated daily oral administration of ≥ 1000 mg/shot in healthy adult men and women, and human clinical trials on NMN safety are limited. Therefore, we conducted a randomized, double-blind, placebo-controlled, parallel-group study to evaluate the safety of 1250 mg of β-NMN administered orally once daily for up to 4 weeks in 31 healthy adult men and women aged 20-65 years. Oral administration of β-NMN did not result in changes exceeding physiological variations in multiple clinical trials, including anthropometry, hematological, biochemical, urine, and body composition analyses. Moreover, no severe adverse events were observed during the study period. Our results indicate that β-NMN is safe and well-tolerated in healthy adult men and women an oral dose of 1250 mg once daily for up to 4 weeks.Trial registration Clinicaltrials.gov Identifier: UMIN000043084. Registered 21/01/2021. https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000049188 .
    133. Kimura S et al.: Nicotinamide Mononucleotide Is Safely Metabolized and Significantly Reduces Blood Triglyceride Levels in Healthy Individuals. Cureus 2022. (PMID 36225528) [PubMed] [DOI] [Full text] An increase in nicotinamide adenine dinucleotide (NAD+) levels alleviates age-related disease progression and promotes healthy life expectancy. Several studies have demonstrated that NAD+ levels can be efficiently replenished via nicotinamide mononucleotide (NMN) intake; additionally, the safety of its oral ingestion has been confirmed in recent clinical trials. However, the efficacy and safety of intravenous NMN administration in humans remain unclear. Therefore, we verified its safety in 10 healthy volunteers. Intravenous administration of NMN did not affect electrocardiograms, pulse, and blood pressure, nor did it affect metabolic markers in the liver, heart, pancreas, and kidneys. These results indicate that intravenous NMN administration is safe and beneficial in humans. Furthermore, NMN administration significantly increased blood NAD+ levels without damaging blood cells and significantly reduced blood triglyceride (TG) levels. These findings imply that intravenous administration of NMN may lead to the prevention and treatment of diseases associated with increased TG levels, such as fatty liver and diabetes.
    134. Yi L et al.: The efficacy and safety of β-nicotinamide mononucleotide (NMN) supplementation in healthy middle-aged adults: a randomized, multicenter, double-blind, placebo-controlled, parallel-group, dose-dependent clinical trial. Geroscience 2023. (PMID 36482258) [PubMed] [DOI] [Full text] In animal studies, β-nicotinamide mononucleotide (NMN) supplementation increases nicotinamide adenine dinucleotide (NAD) concentrations and improves healthspan and lifespan with great safety. However, it is unclear if these effects can be transferred to humans. This randomized, multicenter, double-blind, placebo-controlled, parallel-group, dose-dependent clinical trial included 80 middle-aged healthy adults being randomized for a 60-day clinical trial with once daily oral dosing of placebo, 300 mg, 600 mg, or 900 mg NMN. The primary objective was to evaluate blood NAD concentration with dose-dependent regimens. The secondary objectives were to assess the safety and tolerability of NMN supplementation, next to the evaluation of clinical efficacy by measuring physical performance (six-minute walking test), blood biological age (Aging.Ai 3.0 calculator), Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), and subjective general health assessment [36-Item Short Form Survey Instrument (SF-36)]. Statistical analysis was performed using the Per Protocol analysis with significant level set at p = 0.05. All 80 participants completed the trial without trial protocol violation. Blood NAD concentrations were statistically significantly increased among all NMN-treated groups at day 30 and day 60 when compared to both placebo and baseline (all p ≤ 0.001). Blood NAD concentrations were highest in the groups taking 600 mg and 900 mg NMN. No safety issues, based on monitoring adverse events (AEs), laboratory and clinical measures, were found, and NMN supplementation was well tolerated. Walking distance increase during the six-minute walking test was statistically significantly higher in the 300 mg, 600 mg, and 900 mg groups compared to placebo at both days 30 and 60 (all p < 0.01), with longest walking distances measured in the 600 mg and 900 mg groups. The blood biological age increased significantly in the placebo group and stayed unchanged in all NMN-treated groups at day 60, which resulted in a significant difference between the treated groups and placebo (all p < 0.05). The HOMA-IR showed no statistically significant differences for all NMN-treated groups as compared to placebo at day 60. The change of SF-36 scores at day 30 and day 60 indicated statistically significantly better health of all three treated groups when compared to the placebo group (p < 0.05), except for the SF-36 score change in the 300 mg group at day 30. NMN supplementation increases blood NAD concentrations and is safe and well tolerated with oral dosing up to 900 mg NMN daily. Clinical efficacy expressed by blood NAD concentration and physical performance reaches highest at a dose of 600 mg daily oral intake. This trial was registered with ClinicalTrials.gov, NCT04823260, and Clinical Trial Registry - India, CTRI/2021/03/032421.
    135. Katayoshi T et al.: Nicotinamide adenine dinucleotide metabolism and arterial stiffness after long-term nicotinamide mononucleotide supplementation: a randomized, double-blind, placebo-controlled trial. Sci Rep 2023. (PMID 36797393) [PubMed] [DOI] [Full text] Many animal studies have shown that oral administration of the nicotinamide adenine dinucleotide (NAD+) precursor nicotinamide mononucleotide (NMN) prevents the reduction of NAD+ levels in organs and tissues, helping alleviate aging-related diseases. However, there are very few clinical reports of NMN supplementation in humans. Thus, this study aimed to investigate the influence of a 12-week NMN oral supplementation on biochemical and metabolic health parameters. A 12-week randomized, double-blind, placebo-controlled, parallel-group clinical trial was conducted. A total of 36 healthy middle-aged participants received one capsule of either 125 mg NMN or placebo twice a day. Among the NAD+ metabolites, the levels of nicotinamide in the serum were significantly higher in the NMN intake group than in the placebo group. Pulse wave velocity values indicating arterial stiffness tended to decrease in the NMN intake group. However, no significant difference was found between the two groups. Long-term NMN supplementation at 250 mg/day was well tolerated and did not cause adverse events. NMN safely and effectively elevated NAD+ metabolism in healthy middle-aged adults. Additionally, NMN supplementation showed potential in alleviating arterial stiffness.
    136. Akasaka H et al.: Effects of nicotinamide mononucleotide on older patients with diabetes and impaired physical performance: A prospective, placebo-controlled, double-blind study. Geriatr Gerontol Int 2023. (PMID 36443648) [PubMed] [DOI] OBJECTIVE: Nicotinamide adenine dinucleotide regulates various biological processes. Nicotinamide mononucleotide (NMN) increases its intracellular levels and counteracts age-associated changes in animal models. We investigated the safety and efficacy of oral nicotinamide mononucleotide supplementation in older patients with diabetes and impaired physical performance. METHOD: We carried out a 24-week placebo-controlled, double-blinded study of male patients with diabetes aged ≥65 years with reduced grip strength (<26 kg) or walking speed (<1.0 m/s). The primary end-points were to determine the safety of NMN oral administration (250 mg/day), and changes in grip strength and walking speed. The secondary end-points were to determine the changes in various exploratory indicators. RESULTS: We studied 14 participants aged 81.1 ± 6.4 years. NMN was tolerable without any severe adverse events. The changes in grip strength and walking speed showed no difference between the two groups: 1.25 kg (95% confidence interval -2.31 to 4.81) and 0.033 m/s (-0.021 to 0.087) in the NMN group, and -0.44 kg (-4.15 to 3.26) and 0.014 m/s (-0.16 to -0.13) in the placebo group, respectively. There were no significant differences in any exploratory indicators between the two groups. However, improved prevalence of frailty in the NMN group (P = 0.066) and different changes in central retinal thickness between the two groups (P = 0.051) was observed. CONCLUSION: In older male patients with diabetes and impaired physical performance, NMN supplementation for 24 weeks was safe, but did not improve grip strength and walking speed. Geriatr Gerontol Int 2023; 23: 38-43.
    137. Yamaguchi S et al.: Safety and efficacy of long-term nicotinamide mononucleotide supplementation on metabolism, sleep, and nicotinamide adenine dinucleotide biosynthesis in healthy, middle-aged Japanese men. Endocr J 2024. (PMID 38191197) [PubMed] [DOI] Obesity and aging are major risk factors for several life-threatening diseases. Accumulating evidence from both rodents and humans suggests that the levels of nicotinamide adenine dinucleotide (NAD+), a regulator of many biological processes, declines in multiple organs and tissues with aging and obesity. Administration of an NAD+ intermediate, nicotinamide mononucleotide (NMN), replenishes intracellular NAD+ levels and mitigates aging- and obesity-associated derangements in animal models. In this human clinical study, we aimed to investigate the safety and effects of 8-week oral administration of NMN on biochemical, metabolic, ophthalmologic, and sleep quality parameters as well as on chronological alterations in NAD+ content in peripheral tissues. An 8-week, single-center, single-arm, open-label clinical trial was conducted. Eleven healthy, middle-aged Japanese men received two 125-mg NMN capsules once daily before breakfast. The 8-week NMN supplementation regimen was well-tolerated; NAD+ levels in peripheral blood mononuclear cells increased over the course of NMN administration. In participants with insulin oversecretion after oral glucose loading, NMN modestly attenuated postprandial hyperinsulinemia, a risk factor for coronary artery disease (n = 3). In conclusion, NMN overall safely and effectively boosted NAD+ biosynthesis in healthy, middle-aged Japanese men, showing its potential for alleviating postprandial hyperinsulinemia.
    138. Liang J et al.: Nicotinamide mononucleotide attenuates airway epithelial barrier dysfunction via inhibiting SIRT3 SUMOylation in asthma. Int Immunopharmacol 2023. (PMID 38064810) [PubMed] [DOI] Nicotinamide adenine dinucleotide (NAD+) is an essential element in cellular metabolism that regulates fundamental biological processes. Growing evidence suggests that a decline in NAD+ is a common pathological factor in various diseases and aging. However, its role in airway epithelial barrier function in response to asthma remains underexplored. The current study aims to explore the efficacy of restoring cellular NAD+ concentration through supplementation with the NAD+ precursor, nicotinamide mononucleotide (NMN), in the treatment of allergic asthma and to investigate the role of SIRT3 in mediating the effects of NAD+ precursors. In this research, NMN alleviated airway inflammation and reduced mucus secretion in house dust mite (HDM)-induced asthmatic mice. It also mitigated airway epithelial barrier disruption in HDM-induced asthma in vitro and in vivo. But inhibition of SIRT3 expression abolished the effects of NMN. Mechanistically, HDM induced SIRT3 SUMOylation and proteasomal degradation. Mutation of these two SIRT3 SUMO modification sites enhanced the stability of SIRT3. Additionally, SIRT3 was targeted by SENP1 which acted to de-conjugate SUMO. And down-regulation of SENP1 expression in HDM-induced models was reversed by NMN. Collectively, these findings suggest that NMN attenuates airway epithelial barrier dysfunction via inhibiting SIRT3 SUMOylation in asthma. Blockage of SIRT3 SUMOylation emerges as for the treatment of allergic asthma.
    139. Alegre GFS & Pastore GM: NAD+ Precursors Nicotinamide Mononucleotide (NMN) and Nicotinamide Riboside (NR): Potential Dietary Contribution to Health. Curr Nutr Rep 2023. (PMID 37273100) [PubMed] [DOI] [Full text] PURPOSE OF REVIEW: NAD+ is a vital molecule that takes part as a redox cofactor in several metabolic reactions besides being used as a substrate in important cellular signaling in regulation pathways for energetic, genotoxic, and infectious stress. In stress conditions, NAD+ biosynthesis and levels decrease as well as the activity of consuming enzymes rises. Dietary precursors can promote NAD+ biosynthesis and increase intracellular levels, being a potential strategy for reversing physiological decline and preventing diseases. In this review, we will show the biochemistry and metabolism of NAD+ precursors NR (nicotinamide riboside) and NMN (nicotinamide mononucleotide), the latest findings on their beneficial physiological effects, their interplay with gut microbiota, and the future perspectives for research in nutrition and food science fields. RECENT FINDINGS: NMN and NR demonstrated protect against diabetes, Alzheimer disease, endothelial dysfunction, and inflammation. They also reverse gut dysbiosis and promote beneficial effects at intestinal and extraintestinal levels. NR and NMN have been found in vegetables, meat, and milk, and microorganisms in fermented beverages can also produce them. NMN and NR can be obtained through the diet either in their free form or as metabolites derivate from the digestion of NAD+. The prospection of NR and NMN to find potential food sources and their dietary contribution in increasing NAD+ levels are still an unexplored field of research. Moreover, it could enable the development of new functional foods and processing strategies to maintain and enhance their physiological benefits, besides the studies of new raw materials for extraction and biotechnological development.
    140. Wang H et al.: Nicotinamide Mononucleotide Supplementation Improves Mitochondrial Dysfunction and Rescues Cellular Senescence by NAD+/Sirt3 Pathway in Mesenchymal Stem Cells. Int J Mol Sci 2022. (PMID 36499074) [PubMed] [DOI] [Full text] In vitro expansion-mediated replicative senescence has severely limited the clinical applications of mesenchymal stem cells (MSCs). Accumulating studies manifested that nicotinamide adenine dinucleotide (NAD+) depletion is closely related to stem cell senescence and mitochondrial metabolism disorder. Promoting NAD+ level is considered as an effective way to delay aging. Previously, we have confirmed that nicotinamide mononucleotide (NMN), a precursor of NAD+, can alleviate NAD+ deficiency-induced MSC senescence. However, whether NMN can attenuate MSC senescence and its underlying mechanisms are still incompletely clear. The present study herein showed that late passage (LP) MSCs displayed lower NAD+ content, reduced Sirt3 expression and mitochondrial dysfunction. NMN supplementation leads to significant increase in intracellular NAD+ level, NAD+/ NADH ratio, Sirt3 expression, as well as ameliorated mitochondrial function and rescued senescent MSCs. Additionally, Sirt3 over-expression relieved mitochondrial dysfunction, and retrieved senescence-associated phenotypic features in LP MSCs. Conversely, inhibition of Sirt3 activity via a selective Sirt3 inhibitor 3-TYP in early passage (EP) MSCs resulted in aggravated cellular senescence and abnormal mitochondrial function. Furthermore, NMN administration also improves 3-TYP-induced disordered mitochondrial function and cellular senescence in EP MSCs. Collectively, NMN replenishment alleviates mitochondrial dysfunction and rescues MSC senescence through mediating NAD+/Sirt3 pathway, possibly providing a novel mechanism for MSC senescence and a promising strategy for anti-aging pharmaceuticals.
    141. Covarrubias AJ et al.: NAD+ metabolism and its roles in cellular processes during ageing. Nat Rev Mol Cell Biol 2021. (PMID 33353981) [PubMed] [DOI] [Full text] Nicotinamide adenine dinucleotide (NAD+) is a coenzyme for redox reactions, making it central to energy metabolism. NAD+ is also an essential cofactor for non-redox NAD+-dependent enzymes, including sirtuins, CD38 and poly(ADP-ribose) polymerases. NAD+ can directly and indirectly influence many key cellular functions, including metabolic pathways, DNA repair, chromatin remodelling, cellular senescence and immune cell function. These cellular processes and functions are critical for maintaining tissue and metabolic homeostasis and for healthy ageing. Remarkably, ageing is accompanied by a gradual decline in tissue and cellular NAD+ levels in multiple model organisms, including rodents and humans. This decline in NAD+ levels is linked causally to numerous ageing-associated diseases, including cognitive decline, cancer, metabolic disease, sarcopenia and frailty. Many of these ageing-associated diseases can be slowed down and even reversed by restoring NAD+ levels. Therefore, targeting NAD+ metabolism has emerged as a potential therapeutic approach to ameliorate ageing-related disease, and extend the human healthspan and lifespan. However, much remains to be learnt about how NAD+ influences human health and ageing biology. This includes a deeper understanding of the molecular mechanisms that regulate NAD+ levels, how to effectively restore NAD+ levels during ageing, whether doing so is safe and whether NAD+ repletion will have beneficial effects in ageing humans.
    142. Ito N et al.: Slc12a8 in the lateral hypothalamus maintains energy metabolism and skeletal muscle functions during aging. Cell Rep 2022. (PMID 35905718) [PubMed] [DOI] Sarcopenia and frailty are urgent socio-economic problems worldwide. Here we demonstrate a functional connection between the lateral hypothalamus (LH) and skeletal muscle through Slc12a8, a recently identified nicotinamide mononucleotide transporter, and its relationship to sarcopenia and frailty. Slc12a8-expressing cells are mainly localized in the LH. LH-specific knockdown of Slc12a8 in young mice decreases activity-dependent energy and carbohydrate expenditure and skeletal muscle functions, including muscle mass, muscle force, intramuscular glycolysis, and protein synthesis. LH-specific Slc12a8 knockdown also decreases sympathetic nerve signals at neuromuscular junctions and β2-adrenergic receptors in skeletal muscle, indicating the importance of the LH-sympathetic nerve-β2-adrenergic receptor axis. LH-specific overexpression of Slc12a8 in aged mice significantly ameliorates age-associated decreases in energy expenditure and skeletal muscle functions. Our results highlight an important role of Slc12a8 in the LH for regulation of whole-body metabolism and skeletal muscle functions and provide insights into the pathogenesis of sarcopenia and frailty during aging.