Vitamin B3 forms as precursors to NAD+: Are they safe?

Potential implications of natural compounds on aging and metabolic regulation

Aging is generally accompanied by a progressive loss of metabolic homeostasis. Targeting metabolic processes is an attractive strategy for healthy-aging. Numerous natural compounds have demonstrated strong anti-aging effects. This review summarizes recent findings on metabolic pathways involved in aging and explores the anti-aging effects of natural compounds by modulating these pathways. The potential anti-aging effects of natural extracts rich in biologically active compounds are also discussed. Regulating the metabolism of carbohydrates, proteins, lipids, and nicotinamide adenine dinucleotide is an important strategy for delaying aging. Furthermore, phenolic compounds, terpenoids, alkaloids, and nucleotide compounds have shown particularly promising effects on aging, especially with respect to metabolism regulation. Moreover, metabolomics is a valuable tool for uncovering potential targets against aging. Future research should focus on identifying novel natural compounds that regulate human metabolism and should delve deeper into the mechanisms of metabolic regulation using metabolomics methods, aiming to delay aging and extend lifespan.

Nicotinamide riboside Induced Energy Stress and Metabolic Reprogramming in BEAS-2B Cells

Nicotinamide riboside (NR), a NAD+ precursor, has received attention due to several health benefits it has induced in experimental models. Studies in cultured cells, animals, and humans consistently show increased NAD+ availability after NR supplementation, which is considered the only mode of NR action that leads to health benefits. In the present study, we show that a persistently low NR concentration (1 μM) in the growth medium of BEAS-2B human cells, grown in a monolayer, induces energy stress, which precedes a cellular NAD+ increase after 192 h. NR concentrations greater than 1 μM under the specified conditions were cytotoxic in the 2D cell culture model, while all concentrations tested in the 3D cell culture model (BEAS-2B cell spheroids exposed to 1, 5, 10, and 50 μM NR) induced apoptosis. Shotgun proteomics revealed that NR modulated the abundance of proteins, agreeing with the observed effects on cellular energy metabolism and cell growth or survival. Energy stress may activate pathways that lead to health benefits such as cancer prevention. Accordingly, the premalignant 1198 cell line was more sensitive to NR cytotoxicity than the phenotypically normal parent BEAS-2B cell line. The role of a mild energy stress induced by low concentrations of NR in its beneficial effects deserves further investigation. On the other hand, strategies to increase the bioavailability of NR require attention to toxic effects that may arise.

Mechanistic Insights into the Multiple Functions of Niacinamide: Therapeutic Implications and Cosmeceutical Applications in Functional Skincare Products

Niacinamide (or nicotinamide) is a small-molecule hydrosoluble vitamin with essential metabolic functions in mammalian cells. Niacinamide has become a key functional ingredient in diverse skincare products and cosmetics. This vitamin plays a pivotal role in NAD+ synthesis, notably contributing to redox reactions and energy production in cutaneous cells. Via diversified biochemical mechanisms, niacinamide is also known to influence human DNA repair and cellular stress responses. Based on decades of safe use in cosmetics, niacinamide recently gained widespread popularity as an active ingredient which aligns with the "Kligman standards" in skincare. From a therapeutic standpoint, the intrinsic properties of niacinamide may be applied to managing acne vulgaris, melasma, and psoriasis. From a cosmeceutical standpoint, niacinamide has been widely leveraged as a multipurpose antiaging ingredient. Therein, it was shown to significantly reduce cutaneous oxidative stress, inflammation, and pigmentation. Overall, through multimodal mechanisms, niacinamide may be considered to partially prevent and/or reverse several biophysical changes associated with skin aging. The present narrative review provides multifactorial insights into the mechanisms of niacinamide's therapeutic and cosmeceutical functions. The ingredient's evolving role in skincare was critically appraised, with a strong focus on the biochemical mechanisms at play. Finally, novel indications and potential applications of niacinamide in dermal fillers and alternative injectable formulations were prospectively explored.

Comprehensive Ecotoxicity Studies on Quaternary Ammonium Salts Synthesized from Vitamin B3 Supported by QSAR Calculations

Lately, ionic forms (namely, quaternary ammonium salts, QASs) of nicotinamide, widely known as vitamin B3, are gaining popularity in the sectors developing novel pharmaceuticals and agrochemicals. However, the direct influence of these unique QASs on the development of various terrestrial plants, as well as other organisms, remains unknown. Therefore, three compounds comprising short, medium, and long alkyl chains in N-alkylnicotinamide were selected for phytotoxicity analyses, which were conducted on representative dicotyledonous (white mustard) and monocotyledonous (sorghum) plants. The study allowed the determination of the impact of compounds on the germination capacity as well as on the development of roots and stems of the tested plants. Interestingly, independently of the length of the alkyl chain or plant species, all QASs were established as non-phytotoxic. In addition, QSAR simulations, performed using the EPI Suite™ program pack, allowed the determination of the products' potential toxicity toward fish, green algae, and daphnids along with the susceptibility to biodegradation. The obtained nicotinamide derivative with the shortest chain (butyl) can be considered practically non-toxic according to GHS criteria, whereas salts with medium (decyl) and longest (hexadecyl) substituent were included in the 'acute II' toxicity class. These findings were supported by the results of the toxicity tests performed on the model aquatic plant Lemna minor. It should be stressed that all synthesized salts exhibit not only a lack of potential for bioaccumulation but also lower toxicity than their fully synthetic analogs.

The Central Role of the NAD+ Molecule in the Development of Aging and the Prevention of Chronic Age-Related Diseases: Strategies for NAD+ Modulation

The molecule NAD+ is a coenzyme for enzymes catalyzing cellular redox reactions in several metabolic pathways, encompassing glycolysis, TCA cycle, and oxidative phosphorylation, and is a substrate for NAD+-dependent enzymes. In addition to a hydride and electron transfer in redox reactions, NAD+ is a substrate for sirtuins and poly(adenosine diphosphate-ribose) polymerases and even moderate decreases in its cellular concentrations modify signaling of NAD+-consuming enzymes. Age-related reduction in cellular NAD+ concentrations results in metabolic and aging-associated disorders, while the consequences of increased NAD+ production or decreased degradation seem beneficial. This article reviews the NAD+ molecule in the development of aging and the prevention of chronic age-related diseases and discusses the strategies of NAD+ modulation for healthy aging and longevity.

The dynamics of microbial community and flavor metabolites during the acetic acid fermentation of Hongqu aromatic vinegar

In this study, we investigated the dynamics of microbial community and flavor metabolites during the traditional fermentation of Hongqu aromatic vinegar (HAV) and subsequently explored the potential relationship between microbiota and flavor metabolites. The microbiome analysis based on high-throughput sequencing (HTS) of amplicons demonstrated that Lactobacillus, Acetobacter and Clostridium were the dominant bacterial genera, while Alternaria, Candida, Aspergillus and Issatchenkia were the dominant fungal genera during the acetic acid fermentation (AAF) of HAV. A total of 101 volatile flavor compounds were identified through gas chromatography-mass spectrometry (GC-MS) during HAV fermentation, including esters (35), alcohols (17), aldehydes (11), acids (11), ketones (7), phenols (10), and others (10). Redundancy analysis (RDA) was used to reveal the correlation between microbiota and volatile flavor compounds. Lactobacillus and Acetobacter were the two bacterial genera that have the great influence on the production of volatile flavor components in HAV. Among them, Lactobacillus was positively correlated with a variety of ethyl esters, while Acetobacter positively contributed to the formation of several organic acids. Furthermore, the non-volatile metabolites were detected by ultra-high-performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS). A total of 41 dipeptides were identified during HAV fermentation, and most of them may have sensory characteristics and biological activities. RDA showed that Aspergillus, Epicoccum, Issatchenkia, Candida and Malassezia were the most influential fungal genera on non-volatile metabolites. In particular, Epicoccum was first reported in Hongqu vinegar and showed a positive correlation with the production of various organic acids. In conclusion, this study provides a scientific basis for understanding the flavor generation mechanism of HAV, and may be valuable for developing effective techniques to select suitable strains to improve the flavor quality of HAV.

Current Uncertainties and Future Challenges Regarding NAD+ Boosting Strategies

Precursors of nicotinamide adenine dinucleotide (NAD+), modulators of enzymes of the NAD+ biosynthesis pathways and inhibitors of NAD+ consuming enzymes, are the main boosters of NAD+. Increasing public awareness and interest in anti-ageing strategies and health-promoting lifestyles have grown the interest in the use of NAD+ boosters as dietary supplements, both in scientific circles and among the general population. Here, we discuss the current trends in NAD+ precursor usage as well as the uncertainties in dosage, timing, safety, and side effects. There are many unknowns regarding pharmacokinetics and pharmacodynamics, particularly bioavailability, metabolism, and tissue specificity of NAD+ boosters. Given the lack of long-term safety studies, there is a need for more clinical trials to determine the proper dose of NAD+ boosters and treatment duration for aging prevention and as disease therapy. Further research will also need to address the long-term consequences of increased NAD+ and the best approaches and combinations to increase NAD+ levels. The answers to the above questions will contribute to the more efficient and safer use of NAD+ boosters.

The role of nicotinamide mononucleotide (NMN) in anti-aging, longevity, and its potential for treating chronic conditions

Biosynthesis and regulation of nicotinamide adenine dinucleotide (NAD⁺) has recently gained a lot of attention. A systemic decline in NAD⁺ across many tissues is associated with all the hallmarks of aging. NAD⁺ can affect a variety of cellular processes, including metabolic pathways, DNA repair, and immune cell activity, both directly and indirectly. These cellular processes play a vital role in maintaining homeostasis, but as people get older, their tissue and cellular NAD⁺ levels decrease, and this drop in NAD⁺ levels has been connected to a number of age-related disorders. By restoring NAD⁺ levels, several of these age-related disorders can be delayed or even reversed. Some of the new studies conducted in mice and humans have targeted the NAD⁺ metabolism with NAD⁺ intermediates. Of these, nicotinamide mononucleotide (NMN) has been shown to offer great therapeutic potential with promising results in age-related chronic conditions such as diabetes, cardiovascular issues, cognitive impairment, and many others. Further, human interventions are required to study the long-term effects of supplementing NMN with varying doses. The paper focuses on reviewing the importance of NAD⁺ on human aging and survival, biosynthesis of NAD⁺ from its precursors, key clinical trial findings, and the role of NMN on various health conditions.

Impact of Maternal Feed Restriction at Different Stages of Gestation on the Proteomic Profile of the Newborn Skeletal Muscle

We aimed to investigate the effects of the maternal plane of nutrition during gestation on the proteome profile of the skeletal muscle of the newborn. Pregnant goats were assigned to the following experimental treatments: restriction maintenance (RM) where pregnant dams were fed at 50% of their maintenance requirements from 8−84 days of gestation, and then feed of 100% of the maintenance requirements was supplied from 85—parturition (n = 6); maintenance restriction (MR) where pregnant dams were fed at 100% of their maintenance requirements from 8−84 days of gestation, and then experienced feed restriction of 50% of the maintenance requirements from 85—parturition (n = 8). At birth, newborns were euthanized and samples of the Longissimus dorsi muscle were collected and used to perform HPLC-MS/MS analysis. The network analyses were performed to identify the biological processes and KEGG pathways of the proteins identified as differentially abundant protein and were deemed significant when the adjusted p-value (FDR) < 0.05. Our results suggest that treatment RM affects the energy metabolism of newborns’ skeletal muscle by changing the energy-investment phase of glycolysis, in addition to utilizing glycogen as a carbon source. Moreover, the RM plane of nutrition may contribute to fatty acid oxidation and increases in the cytosolic α-KG and mitochondrial NADH levels in the skeletal muscle of the newborn. On the other hand, treatment MR likely affects the energy-generation phase of glycolysis, contributing to the accumulation of mitochondrial α-KG and the biosynthesis of glutamine.

Nicotinamide Riboside Neutralizes Hypothalamic Inflammation and Increases Weight Loss Without Altering Muscle Mass in Obese Rats Under Calorie Restriction: A Preliminary Investigation

Obesity treatments, such as calorie restriction (CR), eventually lead to muscle wasting and higher rates of neuroinflammation, whereas hypothalamic inflammatory conditions impair body weight (BW) control. Nicotinamide riboside (NR) has been proposed against obesity but with little evidence on skeletal muscle tissue (SMT) and neuroinflammation. Therefore, we aimed to investigate the effects of CR on SMT and on hypothalamic inflammatory biomarkers in obese adult male Wistar rats, and whether NR supplementation alone or in combination with CR affects these parameters. Obesity was induced in rats through a cafeteria diet for 6 weeks. After that, a group of obese rats was exposed to CR, associated or not associated with NR supplementation (400 mg/kg), for another 4 weeks. As a result, obese rats, with or without CR, presented lower relative weight of SMT when compared with eutrophic rats. Rats under CR presented lower absolute SMT weight compared with obese and eutrophic rats, in addition to presenting elevated hypothalamic levels of TNF-α. NR supplementation, in all groups, enhanced weight loss and increased relative weight of the SMT. Furthermore, in animals under CR, NR reversed increases TNF-α levels in the hypothalamus. In this study, these data, although succinct, are the first to evidence the effects of NR on SMT and neuroinflammation when associated with CR, especially in obesity conditions. Therefore, this provides preliminary support for future studies in this investigative field. Furthermore, NR emerges as a potential adjuvant for preventing muscle mass loss in the weight loss processes.

Nicotinamide mononucleotide (NMN) as an anti-aging health product – Promises and safety concerns

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Provides an overview of promises and safety concerns of NMN as an anti-aging product.

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Shows that NMN’s beneficial effects supported by in vivo studies.

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Reveals that there is a lack of NMN’s clinical safety and efficacy studies

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Suggests that proper clinical investigations are urgently needed on the effectiveness and safety of NMN supplementation.

Background

Aim of review

Key scientific concepts of review

Nicotinamide provides neuroprotection in glaucoma by protecting against mitochondrial and metabolic dysfunction

Nicotinamide adenine dinucleotide (NAD) is a REDOX cofactor and metabolite essential for neuronal survival. Glaucoma is a common neurodegenerative disease in which neuronal levels of NAD decline. We assess the effects of nicotinamide (a precursor to NAD) on retinal ganglion cells (the affected neuron in glaucoma) in normal physiological conditions and across a range of glaucoma relevant insults including mitochondrial stress and axon degenerative insults. We demonstrate retinal ganglion cell somal, axonal, and dendritic neuroprotection by nicotinamide in rodent models which represent isolated ocular hypertensive, axon degenerative, and mitochondrial degenerative insults. We performed metabolomics enriched for small molecular weight metabolites for the retina, optic nerve, and superior colliculus which demonstrates that ocular hypertension induces widespread metabolic disruption, including consistent changes to α-ketoglutaric acid, creatine/creatinine, homocysteine, and glycerophosphocholine. This metabolic disruption is prevented by nicotinamide. Nicotinamide provides further neuroprotective effects by increasing oxidative phosphorylation, buffering and preventing metabolic stress, and increasing mitochondrial size and motility whilst simultaneously dampening action potential firing frequency. These data support continued determination of the utility of long-term nicotinamide treatment as a neuroprotective therapy for human glaucoma.

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Nicotinamide is neuroprotective in cell and animal models that recapitulate isolated features of glaucoma.

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Systemic nicotinamide administration has limited molecular side-effects on visual system tissue under basal conditions.

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Nicotinamide provides a robust reversal in the disease metabolic profile of glaucomatous animals.

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Nicotinamide increases oxidative phosphorylation, buffers and prevents metabolic stress, and increases mitochondrial size.

Targeting Diet and Exercise for Neuroprotection and Neurorecovery in Glaucoma

Glaucoma is a leading cause of blindness worldwide. In glaucoma, a progressive dysfunction and death of retinal ganglion cells occurs, eliminating transfer of visual information to the brain. Currently, the only available therapies target the lowering of intraocular pressure, but many patients continue to lose vision. Emerging pre-clinical and clinical evidence suggests that metabolic deficiencies and defects may play an important role in glaucoma pathophysiology. While pre-clinical studies in animal models have begun to mechanistically uncover these metabolic changes, some existing clinical evidence already points to potential benefits in maintaining metabolic fitness. Modifying diet and exercise can be implemented by patients as an adjunct to intraocular pressure lowering, which may be of therapeutic benefit to retinal ganglion cells in glaucoma.

Healthy Lifestyle Recommendations: Do the Beneficial Effects Originate from NAD+ Amount at the Cellular Level?

In this review, we describe the role of oxidized forms of nicotinamide adenine dinucleotide (NAD⁺) as a molecule central to health benefits as the result from observing selected healthy lifestyle recommendations. Namely, NAD⁺ level can be regulated by lifestyle and nutrition approaches such as fasting, caloric restriction, sports activity, low glucose availability, and heat shocks. NAD⁺ is reduced with age at a cellular, tissue, and organismal level due to inflammation, defect in NAMPT-mediated NAD⁺ biosynthesis, and the PARP-mediated NAD⁺ depletion. This leads to a decrease in cellular energy production and DNA repair and modifies genomic signalling leading to an increased incidence of chronic diseases and ageing. By implementing healthy lifestyle approaches, endogenous intracellular NAD⁺ levels can be increased, which explains the molecular mechanisms underlying health benefits at the organismal level. Namely, adherence to here presented healthy lifestyle approaches is correlated with an extended life expectancy free of major chronic diseases.

Nicotinamide riboside reduces cardiometabolic risk factors and modulates cardiac oxidative stress in obese Wistar rats under caloric restriction

AIMS

NAD-based therapeutic strategies are encouraged against obesity and heart disease. Our study, therefore, aimed to investigate the effects of nicotinamide riboside (NR), isolated or combined with caloric restriction (CR), both approaches well-known for stimulating NAD levels, on adiposity parameters, cardiometabolic factors and cardiac oxidative stress in rats submitted to cafeteria diet (CAF).

MAIN METHODS

After 42 days of CAF-induced obesity (hypercaloric and ultra-processed foods common to humans), we examined the effects of oral administration of NR (400 mg/kg for 28 days), combined or not with CR (-62% kcal, for 28 days), on anthropometric, metabolic, tissue, and cardiac oxidative stress parameters in obese male Wistar rats.

KEY FINDINGS

In obese rats, treatment with NR alone mitigated final body weight gain, reduced adiposity (visceral and subcutaneous), improved insulin resistance, and decreased TG/HDL ratio and heart size. In cardiac OS, treatment with NR increased the antioxidant capacity via glutathione peroxidase and catalase enzymes (in rats under CR) as well as reduced the pro-oxidant complex NADPH oxidase (in obese and lean rats). Hyperglycemia, hypertriglyceridemia and elevated levels of TBARS in the heart were state-dependent adverse effects, induced by treatment with NR.

SIGNIFICANCE

This is the first study to report effects of nicotinamide riboside on cardiac oxidative stress in an obesity model. Nicotinamide riboside, a natural dietary compound, presented antiobesity effects and cardiometabolic benefits, in addition to positively modulating oxidative stress in the heart, in a state-dependent manner.

Potential Therapeutic Benefit of NAD+ Supplementation for Glaucoma and Age-Related Macular Degeneration

Glaucoma and age-related macular degeneration are leading causes of irreversible blindness worldwide with significant health and societal burdens. To date, no clinical cures are available and treatments target only the manageable symptoms and risk factors (but do not remediate the underlying pathology of the disease). Both diseases are neurodegenerative in their pathology of the retina and as such many of the events that trigger cell dysfunction, degeneration, and eventual loss are due to mitochondrial dysfunction, inflammation, and oxidative stress. Here, we critically review how a decreased bioavailability of nicotinamide adenine dinucleotide (NAD; a crucial metabolite in healthy and disease states) may underpin many of these aberrant mechanisms. We propose how exogenous sources of NAD may become a therapeutic standard for the treatment of these conditions.

Nicotinamide riboside-A missing piece in the puzzle of exercise therapy for older adults?

Maintaining physical mobility is important for preventing age-related comorbidities in older adults. Endurance and resistance training prevent mobility loss in aging, but exercise alone does not always achieve the expected improvements in physical and cardiopulmonary function. Recent preclinical evidence suggests that a reason for the variability in exercise training responses may be the age-related dysregulation of the nicotinamide adenine dinucleotide (NAD+) metabolome. NAD+ is an essential enzymatic cofactor in energetic and signaling pathways. Endogenous NAD+ pool is lower in several chronic and degenerative diseases (e.g., cardiovascular diseases, Alzheimer's and Parkinson's diseases, muscular dystrophies), and also in aging. Exercise requires a higher energy expenditure than a resting state, thus a state of NAD+ insufficiency with reduced energy metabolism, could result in an inadequate exercise response. Recently, the NAD+ precursor nicotinamide riboside (NR), a vitamin B3 derivate, showed an ability to improve NAD+ metabolome homeostasis, restoring energy metabolism and cellular function in various organs in animals. NR has also been tested in older humans and is considered safe, but the effects of NR supplementation alone on physical performance are unclear. The purpose of this review is to examine the preclinical and clinical evidence on the effect of NR supplementation strategies alone and in combination with physical activity on mobility and skeletal muscle and cardiovascular function.

Yin and Yang: Why did evolution implement and preserve the circadian rhythmicity?

Yin and Yang concept emphasizes the reciprocal and interrelated nature; neither is sufficient, both are needed to sustain the overall balance of the living system. Changing the balance, by implementing deficiency or excess of one of them, upsets the equilibrium (homeostasis) of the whole system.

PURPOSE

In this opinion article intermittent exposure is presented as the stimulus for development and evolutionary conservation of circadian rhythm, an endogenous, entrainable oscillation of approximately 24 h, to counteract/balance the cells' natural tendency to attenuate their response during long-term exposure to different endogenous substances.

RESULTS

The concept of Yin and Yang duality is an allegory on which the avoidance of attenuation of the cells' responses hypothesis is presented as an explanation for the circadian rhythmicity, which is integrated in all human cells, with the exception of stem and cancer cells.

CONCLUSIONS

We hypothesize, that circadian rhythmicity has evolved, during evolution, into a mechanism that prevents disruption of the organism's negative-feedback-loop homeostasis.