Effect of oral administration of nicotinamide mononucleotide on clinical parameters and nicotinamide metabolite levels in healthy Japanese men

Anti-aging effects of medicinal plants and their rapid screening using the nematode Caenorhabditis elegans

BACKGROUND

Aging is the primary risk factor of most chronic diseases in humans, including cardiovascular diseases, osteoporosis and neurodegenerative diseases, which extensively damage the quality of life for elderly individuals. Aging is a multifaceted process with numerous factors affecting it. Efficient model organisms are essential for the research and development of anti-aging agents, particularly when investigating pharmacological mechanisms are needed.

PURPOSE

This review discusses the application of Caenorhabditis elegans for studying aging and its related signaling pathways, and presents an overview of studies exploring the mechanism and screening of anti-aging agents in C. elegans. Additionally, the review summarizes related clinical trials of anti-aging agents to inspire the development of new medications.

METHOD

Literature was searched, analyzed, and collected using PubMed, Web of Science, and Science Direct. The search terms used were "anti-aging", "medicinal plants", "synthetic compounds", "C. elegans", "signal pathway", etc. Several combinations of these keywords were used. Studies conducted in C. elegans or humans were included. Articles were excluded, if they were on studies conducted in silico or in vitro or could not offer effective data.

RESULTS

Four compounds mainly derived through synthesis (metformin, rapamycin, nicotinamide mononucleotide, alpha-ketoglutarate) and four active ingredients chiefly obtained from plants (resveratrol, quercetin, Astragalus polysaccharide, ginsenosides) are introduced emphatically. These compounds and active ingredients exhibit potential anti-aging effects in preclinical and clinical studies. The screening of these anti-aging agents and the investigation of their pharmacological mechanisms can benefit from the use of C. elegans.

CONCLUSION

Medicinal plants provide valuable resource for the treatment of diseases. A wide source of raw materials for the particular plant medicinal compounds having anti-aging effects meet diverse pharmaceutical requirements, such as immunomodulatory, anti-inflammation and alleviating oxidative stress. C. elegans possesses advantages in scientific research including short life cycle, small size, easy maintenance, genetic tractability and conserved biological processes related to aging. C. elegans can be used for the efficient and rapid evaluation of compounds with the potential to slow down aging.

Therapeutic Effects of Anti-Inflammatory and Anti-Oxidant Nutritional Supplementation in Retinal Ischemic Diseases

Appropriate nutrients are essential for cellular function. Dietary components can alter the risk of systemic metabolic diseases, including cardiovascular diseases, cancer, diabetes, and obesity, and can also affect retinal diseases, including age-related macular degeneration, diabetic retinopathy, and glaucoma. Dietary nutrients have been assessed for the prevention or treatment of retinal ischemic diseases and the diseases of aging. In this article, we review clinical and experimental evidence concerning the potential of some nutritional supplements to prevent or treat retinal ischemic diseases and provide further insights into the therapeutic effects of nutritional supplementation on retinopathies. We will review the roles of nutrients in preventing or protecting against retinal ischemic diseases.

Nicotinamide mononucleotide induces autophagy and ferroptosis via AMPK/mTOR pathway in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a common malignancy worldwide. Herein, we investigated the role of nicotinamide mononucleotide (NMN) in HCC progression. HCC cells were treated with NMN (125, 250, and 500 μM), and then nicotinamide adenine dinucleotide (NAD+ ) and NADH levels in HCC cells were measured to calculate NAD+ /NADH ratio. Cell proliferation, apoptosis, autophagy and ferroptosis were determined. AMPK was knocked down to confirm the involvement of AMPK/mTOR signaling. Furthermore, tumor-inhibitory effect of NMN was investigated in xenograft models. Exposure to NMN dose-dependently increased NAD+ level and NAD+ /NADH ratio in HCC cells. After NMN treatment, cell proliferation was inhibited, whereas apoptosis was enhanced in both cell lines. Additionally, NMN dose-dependently enhanced autophagy/ferroptosis and activated AMPK/mTOR pathway in HCC cells. AMPK knockdown partially rescued the effects of NMN in vitro. Furthermore, NMN treatment restrained tumor growth in nude mice, activated autophagy/ferroptosis, and promoted apoptosis and necrosis in tumor tissues. The results indicate that NMN inhibits HCC progression by inducing autophagy and ferroptosis via AMPK/mTOR signaling. NMN may serve as a promising agent for HCC treatment.

Role and Potential Mechanisms of Nicotinamide Mononucleotide in Aging

Nicotinamide adenine dinucleotide (NAD+) has recently attracted much attention due to its role in aging and lifespan extension. NAD+ directly and indirectly affects many cellular processes, including metabolic pathways, DNA repair, and immune cell activities. These mechanisms are critical for maintaining cellular homeostasis. However, the decline in NAD+ levels with aging impairs tissue function, which has been associated with several age-related diseases. In fact, the aging population has been steadily increasing worldwide, and it is important to restore NAD+ levels and reverse or delay these age-related disorders. Therefore, there is an increasing demand for healthy products that can mitigate aging, extend lifespan, and halt age-related consequences. In this case, several studies in humans and animals have targeted NAD+ metabolism with NAD+ intermediates. Among them, nicotinamide mononucleotide (NMN), a precursor in the biosynthesis of NAD+, has recently received much attention from the scientific community for its anti-aging properties. In model organisms, ingestion of NMN has been shown to improve age-related diseases and probably delay death. Here, we review aspects of NMN biosynthesis and the mechanism of its absorption, as well as potential anti-aging mechanisms of NMN, including recent preclinical and clinical tests, adverse effects, limitations, and perceived challenges.

Nicotinamide mononucleotide, a potential future treatment in ocular diseases

PURPOSE

The burden of ocular diseases has been gradually increasing worldwide. Various factors are suggested for the development and progression of ocular diseases, such as ocular inflammation, oxidative stress, and complex metabolic dysregulation. Thus, managing ocular diseases requires the modulation of pathologic signaling pathways through many mechanisms. Nicotinamide mononucleotide (NMN) is a bioactive molecule naturally found in life forms. NMN is a direct precursor of the important molecule nicotinamide adenine dinucleotide (NAD+), an essential co-enzyme required for enormous cellular functions in most life forms. While the recent experimental evidence of NMN treatment in various metabolic diseases has been well-reviewed, NMN treatment in ocular diseases has not been comprehensively summarized yet. In this regard, we aimed to focus on the therapeutic roles of NMN treatment in various ocular diseases with recent advances.

METHODS

How we came to our current opinion with a recent summary was described based on our own recent reports as well as a search of the related literature.

RESULTS

We found that NMN treatment might be available for the prevention of and protection from various experimental ocular diseases, as NMN treatment modulated ocular inflammation, oxidative stress, and complex metabolic dysregulation in murine models for eye diseases such as ischemic retinopathy, corneal defect, glaucoma, and age-related macular degeneration.

CONCLUSION

Our current review suggests and discusses new modes of actions of NMN for the prevention of and protection from various ocular diseases and can urge future research to obtain more solid evidence on a potential future NMN treatment in ocular diseases at the preclinical stages.

Metabolites in aging and aging-relevant diseases: Frailty, sarcopenia and cognitive decline

Aging shows biologically complex features with high individual variability, which reflects the exposure to several stimuli and the adaptation to them. Among them, metabolic changes are well observed as consequences or possible causes of aging. Calorie restriction extends organismal life span in experimental models. Several metabolites; for example, resveratrol or nicotinamide mononucleotide, are reported to mimic calorie restriction effects in vivo. Metabolomic research would be useful to evaluate metabolites as biomarkers in aging-relevant events and to identify metabolic regulation of aging. We recently developed the metabolomic approach for whole blood analysis, which functions as strong tool for this purpose. We review the update findings in aging-relevant metabolites detected by this method. Geriatr Gerontol Int 2024; 24: 44-48.

Biosynthesis of Nicotinamide Mononucleotide: Synthesis Method, Enzyme, and Biocatalytic System

Nicotinamide mononucleotide (NMN) has garnered substantial interest as a functional food product. Industrial NMN production relies on chemical methods, facing challenges in separation, purification, and regulatory complexities, leading to elevated prices. In contrast, NMN biosynthesis through fermentation or enzyme catalysis offers notable benefits like eco-friendliness, recyclability, and efficiency, positioning it as a primary avenue for future NMN synthesis. Enzymatic NMN synthesis encompasses the nicotinamide-initial route and nicotinamide ribose-initial routes. Key among these is nicotinamide riboside kinase (NRK), pivotal in the latter route. The NRK-mediated biosynthesis is emerging as a prominent trend due to its streamlined route, simplicity, and precise specificity. The essential aspect is to obtain an engineered NRK that exhibits elevated activity and robust stability. This review comprehensively assesses diverse NMN synthesis methods, offering valuable insights into efficient, sustainable, and economical production routes. It spotlights the emerging NRK-mediated biosynthesis pathway and its significance. The establishment of an adenosine triphosphate (ATP) regeneration system plays a pivotal role in enhancing NMN synthesis efficiency through NRK-catalyzed routes. The review aims to be a reference for researchers developing green and sustainable NMN synthesis, as well as those optimizing NMN production.

The use of a systems approach to increase NAD+ in human participants

Reversal or mitigation against an age-related decline in NAD+ has likely benefits, and this premise has driven academic and commercial endeavour to develop dietary supplements that achieve this outcome. We used a systems-based approach to improve on current supplements by targeting multiple points in the NAD+ salvage pathway. In a double-blind, randomised, crossover trial, the supplement - Nuchido TIME+® (NT) - increased NAD+ concentration in whole blood. This was associated with an increase in SIRT1 and an increase in nicotinamide phosphoribosyltransferase (NAMPT) in peripheral blood mononucleocytes, lower concentrations of pro-inflammatory cytokines in plasma, including a reduction in interleukin 2 (IL2), a reduction in glycated serum protein and a shift in the glycosylation profile of immunoglobulin G (IgG) toward a younger biological age, all of which are likely to promote a healthier ageing trajectory.

Chronic dietary supplementation with nicotinamide riboside reduces sleep need in the laboratory mouse

Non-rapid eye movement sleep (NREMS) is accompanied by a reduction in cerebral glucose utilization. Enabling this metabolic change may be a central function of sleep. Since the reduction in glucose metabolism is inevitably accompanied by deceleration of downstream oxidation/reduction reactions involving nicotinamide adenine dinucleotide (NAD), we hypothesized a role for NAD in regulating the homeostatic dynamics of sleep at the biochemical level. We applied dietary nicotinamide riboside (NR), a NAD precursor, in a protocol known to improve neurological outcome measures in mice. Long-term (6-10 weeks) dietary supplementation with NR reduced the time that mice spent in NREMS by 17 percent and accelerated the rate of discharge of sleep need according to a mathematical model of sleep homeostasis (Process S). These findings suggest that increasing redox capacity by increasing nicotinamide availability reduces sleep need and increases the cortical capacity for energetically demanding high-frequency oscillations. In turn, this work demonstrates the impact of redox substrates on cortical circuit properties related to fatigue and sleep drive, implicating redox reactions in the homeostatic dynamics of cortical network events across sleep-wake cycles.

Nicotinamide mononucleotide as a therapeutic agent to alleviate multi-organ failure in sepsis

BACKGROUND

Sepsis-caused multi-organ failure remains the major cause of morbidity and mortality in intensive care units with limited therapeutics. Nicotinamide mononucleotide (NMN), a precursor of nicotinamide adenine dinucleotide (NAD+), has been recently reported to be protective in sepsis; however, its therapeutic effects remain to be determined. This study sought to investigate the therapeutic effects of NMN in septic organ failure and its underlying mechanisms.

METHODS

Sepsis was induced by feces-injection-in-peritoneum in mice. NMN was given after an hour of sepsis onset. Cultured neutrophils, macrophages and endothelial cells were incubated with various agents.

RESULTS

We demonstrate that administration of NMN elevated NAD+ levels and reduced serum lactate levels, oxidative stress, inflammation, and caspase-3 activity in multiple organs of septic mice, which correlated with the attenuation of heart dysfunction, pulmonary microvascular permeability, liver injury, and kidney dysfunction, leading to lower mortality. The therapeutic effects of NMN were associated with lower bacterial burden in blood, and less ROS production in septic mice. NMN improved bacterial phagocytosis and bactericidal activity of macrophages and neutrophils while reducing the lipopolysaccharides-induced inflammatory response of macrophages. In cultured endothelial cells, NMN mitigated mitochondrial dysfunction, inflammation, apoptosis, and barrier dysfunction induced by septic conditions, all of which were offset by SIRT3 inhibition.

CONCLUSION

NAD+ repletion with NMN prevents mitochondrial dysfunction and restrains bacterial dissemination while limiting inflammatory damage through SIRT3 signaling in sepsis. Thus, NMN may represent a therapeutic option for sepsis.

Impact of NAD+ metabolism on ovarian aging

Nicotinamide adenine dinucleotide (NAD+), a crucial coenzyme in cellular redox reactions, is closely associated with age-related functional degeneration and metabolic diseases. NAD exerts direct and indirect influences on many crucial cellular functions, including metabolic pathways, DNA repair, chromatin remodeling, cellular senescence, and immune cell functionality. These cellular processes and functions are essential for maintaining tissue and metabolic homeostasis, as well as healthy aging. Causality has been elucidated between a decline in NAD levels and multiple age-related diseases, which has been confirmed by various strategies aimed at increasing NAD levels in the preclinical setting. Ovarian aging is recognized as a natural process characterized by a decline in follicle number and function, resulting in decreased estrogen production and menopause. In this regard, it is necessary to address the many factors involved in this complicated procedure, which could improve fertility in women of advanced maternal age. Concerning the decrease in NAD+ levels as ovarian aging progresses, promising and exciting results are presented for strategies using NAD+ precursors to promote NAD+ biosynthesis, which could substantially improve oocyte quality and alleviate ovarian aging. Hence, to acquire further insights into NAD+ metabolism and biology, this review aims to probe the factors affecting ovarian aging, the characteristics of NAD+ precursors, and the current research status of NAD+ supplementation in ovarian aging. Specifically, by gaining a comprehensive understanding of these aspects, we are optimistic about the prominent progress that will be made in both research and therapy related to ovarian aging.

NAD+ Precursors in Human Health and Disease: Current Status and Future Prospects

Significance: Nicotinamide adenine dinucleotide (NAD+) acts as a cofactor in many important biological processes. The administration of NAD+ precursors increases the intracellular NAD+ pool and has beneficial effects on physiological changes and diseases associated with aging in various organisms, including rodents and humans. Recent Advances: Evidence from preclinical studies demonstrating the beneficial effects of NAD+ precursors has rapidly increased in the last decade. The results of these studies have prompted the development of clinical trials using NAD+ precursors, particularly nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN). In addition, in vivo studies of NAD+ metabolism have rapidly progressed. Critical Issues: Several studies have demonstrated that the oral administration of NAD+ precursors, such as NR and NMN, is safe and significantly increases NAD+ levels in humans. However, the efficacy of these NAD+ precursors is lower than expected from the results of preclinical studies. In addition, the identification of the contribution of the host-gut microbiota interactions to NR and NMN metabolism has added to the complexity of NAD+ metabolism. Future Directions: Further studies are required to determine the efficacy of NAD+ precursors in humans. Further in vivo studies of NAD+ metabolism are required to optimize the effects of NAD+ supplementation. There is also a need for methods of delivering NAD+ precursors to target organs or tissues to increase the outcomes of clinical trials. Antioxid. Redox Signal. 39, 1133-1149.

The Safety and Antiaging Effects of Nicotinamide Mononucleotide in Human Clinical Trials: an Update

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.

NAD+ Precursors Nicotinamide Mononucleotide (NMN) and Nicotinamide Riboside (NR): Potential Dietary Contribution to Health

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.

The autophagy-NAD axis in longevity and disease

Autophagy is an intracellular degradation pathway that recycles subcellular components to maintain metabolic homeostasis. NAD is an essential metabolite that participates in energy metabolism and serves as a substrate for a series of NAD+-consuming enzymes (NADases), including PARPs and SIRTs. Declining levels of autophagic activity and NAD represent features of cellular ageing, and consequently enhancing either significantly extends health/lifespan in animals and normalises metabolic activity in cells. Mechanistically, it has been shown that NADases can directly regulate autophagy and mitochondrial quality control. Conversely, autophagy has been shown to preserve NAD levels by modulating cellular stress. In this review we highlight the mechanisms underlying this bidirectional relationship between NAD and autophagy, and the potential therapeutic targets it provides for combatting age-related disease and promoting longevity.

Nicotinamide mononucleotide (NMN) intake increases plasma NMN and insulin levels in healthy subjects

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.

Insights into structural, spectroscopic, and hydrogen bonding interaction patterns of nicotinamide-oxalic acid (form I) salt by using experimental and theoretical approaches

In the present work, nicotinamide-oxalic acid (NIC-OXA, form I) salt was crystallized by slow evaporation of an aqueous solution. To understand the molecular structure and spectroscopic properties of NIC after co-crystallization with OXA, experimental infrared (IR), Raman spectroscopic signatures, X-ray powder diffraction (XRPD), and differential scanning calorimetry (DSC) techniques were used to characterize and validate the salt. The density functional theory (DFT) methodology was adopted to perform all theoretical calculations by using the B3LYP/6-311++G (d, p) functional/basis set. The experimental geometrical parameters were matched in good correlation with the theoretical parameters of the dimer than the monomer, due to the fact of covering the nearest hydrogen bonding interactions present in the crystal structure of the salt. The IR and Raman spectra of the dimer showed the red (downward) shifting and broadening of bands among (N15-H16), (N38-H39), and (C13=O14) bonds of NIC and (C26=O24), (C3=O1), and (C26=O25) groups of OXA, hence involved in the formation of NIC-OXA salt. The atoms in molecules (AIM) analysis revealed that (N8-H9···O24) is the strongest (conventional) intermolecular hydrogen bonding interaction in the dimer model of salt with the maximum value of interaction energy -12.1 kcal mol-1. Furthermore, the natural bond orbital (NBO) analysis of the Fock matrix showed that in the dimer model, the (N8-H9···O24) bond is responsible for the stabilization of the salt with an energy value of 13.44 kcal mol-1. The frontier molecular orbitals (FMOs) analysis showed that NIC-OXA (form I) salt is more reactive and less stable than NIC, as the energy gap of NIC-OXA (form I) salt is less than that of NIC. The global and local reactivity descriptor parameters were calculated for the monomer and dimer models of the salt. The electrophilic, nucleophilic, and neutral reactive sites of NIC, OXA, monomer, and dimer models of salt were visualized by plotting the molecular electrostatic potential (MESP) surface. The study provides valuable insights into combining both experimental and theoretical results that could define the physicochemical properties of molecules.

Effect of Exercise and Oral Niacinamide Mononucleotide on Improving Mitochondrial Autophagy in Alzheimer's Disease

Oral niacinamide mononucleotide (NMN) and aerobic exercise have been shown to enhance niacinamide adenine dinucleotide (NAD⁺) in the body. NAD⁺ plays a critical role in the body and can directly and indirectly affect many key cellular functions, including metabolic pathways, DNA repair, chromatin remodeling, cell aging, and immune cell function. It is noteworthy that the level of NAD⁺ decreases gradually with increasing age. Decreased levels of NAD⁺ have been causally associated with a number of diseases associated with aging, including cognitive decline, cancer, metabolic diseases, sarcopenia, and frailty. Many diseases related to aging can be slowed down or even reversed by restoring NAD⁺ levels. For example, oral NMN or exercise to increase NAD⁺ levels in APP/PS1 mice have been proven to improve mitochondrial autophagy, but currently, there is no regimen combining oral NMN with exercise. This review summarizes recent studies on the effect of oral NMN on the enhancement of NAD⁺ in vivo and the improvements in mitochondrial autophagy abnormalities in AD through aerobic exercise, focusing on (1) how oral NMN improves the internal NAD⁺ level; (2) how exercise regulates the content of NAD⁺ in the body; (3) the relationship between exercise activation of NAD⁺ and AMPK; (4) how SIRT1 is regulated by NAD⁺ and AMPK and activates PGC-1α to mediate mitochondrial autophagy through changes in mitochondrial dynamics. By summarizing the results of the above four aspects, and combined with the synthesis of NAD⁺ in vivo, we can infer how exercise elevates the level of NAD⁺ in vivo to mediate mitochondrial autophagy, so as to propose a new hypothesis that exercise interferes with Alzheimer's disease (AD).

Nicotinamide mononucleotide (NMN) ameliorated Nonylphenol-induced learning and memory impairment in rats via the central 5-HT system and the NAD+/SIRT1/MAO-A pathway

Nonylphenol (NP) exposure can trigger neurotoxicity and cause learning and memory impairment. Nicotinamide mononucleotide (NMN) has a therapeutic effect on neurodegenerative diseases, but the role of NMN on NP-induced learning and memory impairment is not known. Here, we examined the mitigative effect of NMN on the impaired learning and memory ability of rats exposed to NP. The NP impaired learning and memory in rats, while the low-dose intervention with NMN significantly prolonged the step-through latency of the PAT and improved the NAMPT and NMNAT1 content in brain tissue. At the same time, the NMN intervention also increased the content of 5-HTR_1A, 5-HTR₄, and 5-HTR₆ related to learning and memory in the hippocampus. In line with this, we found that the NMN intervention activated the SIRT1/MAO-A pathway in brain tissue. NMN intervention, especially at 125 mg/kg doses, may improve rats' NP-induced learning and memory impairment via the central 5-HT system and the NAD⁺/SIRT1/MAO-A pathway in the brain.

Oral nicotinamide mononucleotide (NMN) to treat chronic insomnia: protocol for the multicenter, randomized, double-blinded, placebo-controlled trial

BACKGROUND

The treatment of insomnia, which is the most common sleep disorder, includes drug and behavioral treatment, but each treatment measure has its limitations. So new treatment method needs to be taken to improve the treatment effect. MN supplementation is a potential promising new method for the treatment of insomnia, resulting in a rising need for methodological research towards verifying its efficacy.

METHODS/DESIGN

We describe a proposal for a multicenter, patient-assessor-blinded, randomized controlled trial with two parallel arms. A total of 400 chronic insomnia patients will be allocated 1:1 to the intervention group (treatment with oral NMN 320 mg/day) or control group (treatment with oral placebo). All subjects are clinical chronic insomnia patients who meet all inclusion criteria. All subjects are treated by taking NMN or placebo. The primary outcome is the score on the Pittsburgh Sleep Quality Index (PSQI). Secondary outcomes are the score on the Insomnia Severity Index (ISI) and Epworth Sleeping Scale (ESS), the total sleep time (TST), sleep efficiency (SE), sleep latency, and REM sleep latency to assess sleep quality changes. Subjects are assessed at two time points: baseline and follow-up. The duration of the clinical trial is 60 days.

DISCUSSION

This study will provide more evidence on the effects of NMN on improving sleep quality among patients with chronic insomnia. If proven effective, NMN supplement can be used as a new treatment for chronic insomnia in the future.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (chictr.org.cn) ChiCTR2200058001. Registered on 26 March 2022.

SIRT6-PAI-1 axis is a promising therapeutic target in aging-related bone metabolic disruption

The mechanistic regulation of bone mass in aged animals is poorly understood. In this study, we examined the role of SIRT6, a longevity-associated factor, in osteocytes, using mice lacking Sirt6 in Dmp-1-expressing cells (cKO mice) and the MLO-Y4 osteocyte-like cell line. cKO mice exhibited increased osteocytic expression of Sost, Fgf23 and senescence inducing gene Pai-1 and the senescence markers p16 and Il-6, decreased serum phosphate levels, and low-turnover osteopenia. The cKO phenotype was reversed in mice that were a cross of PAI-1-null mice with cKO mice. Furthermore, senescence induction in MLO-Y4 cells increased the Fgf23 and Sost mRNA expression. Sirt6 knockout and senescence induction increased HIF-1α binding to the Fgf23 enhancer sequence. Bone mass and serum phosphate levels were higher in PAI-1-null aged mice than in wild-type mice. Therefore, SIRT6 agonists or PAI-1 inhibitors may be promising therapeutic options for aging-related bone metabolism disruptions.

Interactions between Intestinal Homeostasis and NAD+ Biology in Regulating Incretin Production and Postprandial Glucose Metabolism

The intestine has garnered attention as a target organ for developing new therapies for impaired glucose tolerance. The intestine, which produces incretin hormones, is the central regulator of glucose metabolism. Glucagon-like peptide-1 (GLP-1) production, which determines postprandial glucose levels, is regulated by intestinal homeostasis. Nicotinamide phosphoribosyltransferase (NAMPT)-mediated nicotinamide adenine dinucleotide (NAD⁺) biosynthesis in major metabolic organs such as the liver, adipose tissue, and skeletal muscle plays a crucial role in obesity- and aging-associated organ derangements. Furthermore, NAMPT-mediated NAD⁺ biosynthesis in the intestines and its upstream and downstream mediators, adenosine monophosphate-activated protein kinase (AMPK) and NAD⁺-dependent deacetylase sirtuins (SIRTs), respectively, are critical for intestinal homeostasis, including gut microbiota composition and bile acid metabolism, and GLP-1 production. Thus, boosting the intestinal AMPK-NAMPT-NAD⁺-SIRT pathway to improve intestinal homeostasis, GLP-1 production, and postprandial glucose metabolism has gained significant attention as a novel strategy to improve impaired glucose tolerance. Herein, we aimed to review in detail the regulatory mechanisms and importance of intestinal NAMPT-mediated NAD⁺ biosynthesis in regulating intestinal homeostasis and GLP-1 secretion in obesity and aging. Furthermore, dietary and molecular factors regulating intestinal NAMPT-mediated NAD⁺ biosynthesis were critically explored to facilitate the development of new therapeutic strategies for postprandial glucose dysregulation.

Emerging Therapeutic Approaches to Target the Dark Side of Senescent Cells: New Hopes to Treat Aging as a Disease and to Delay Age-Related Pathologies

Life expectancy has drastically increased over the last few decades worldwide, with important social and medical burdens and costs. To stay healthy longer and to avoid chronic disease have become essential issues. Organismal aging is a complex process that involves progressive destruction of tissue functionality and loss of regenerative capacity. One of the most important aging hallmarks is cellular senescence, which is a stable state of cell cycle arrest that occurs in response to cumulated cell stresses and damages. Cellular senescence is a physiological mechanism that has both beneficial and detrimental consequences. Senescence limits tumorigenesis, lifelong tissue damage, and is involved in different biological processes, such as morphogenesis, regeneration, and wound healing. However, in the elderly, senescent cells increasingly accumulate in several organs and secrete a combination of senescence associated factors, contributing to the development of various age-related diseases, including cancer. Several studies have revealed major molecular pathways controlling the senescent phenotype, as well as the ones regulating its interactions with the immune system. Attenuating the senescence-associated secretory phenotype (SASP) or eliminating senescent cells have emerged as attractive strategies aiming to reverse or delay the onset of aging diseases. Here, we review current senotherapies designed to suppress the deleterious effect of SASP by senomorphics or to selectively kill senescent cells by "senolytics" or by immune system-based approaches. These recent investigations are promising as radical new controls of aging pathologies and associated multimorbidities.

Biotechnological production of reduced and oxidized NAD+ precursors

Dysregulation of nicotinamide adenine dinucleotide (NAD⁺) homeostasis by increased activity of NAD⁺ consumers or reduced NAD⁺ biosynthesis plays an important role in the onset of prevalent, often age-related, diseases, such as diabetes, neuropathies or nephropathies. To counteract such dysregulation, NAD⁺ replenishment strategies can be used. Among these, administration of vitamin B₃ derivatives (NAD⁺ precursors) has garnered attention in recent years. However, the high market price of these compounds and their limited availability, pose important limitations to their use in nutritional or biomedical applications. To overcome these limitations, we have designed an enzymatic method for the synthesis and purification of (1) the oxidized NAD⁺ precursors nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR), (2) their reduced forms NMNH and NRH, and (3) their deaminated forms nicotinic acid mononucleotide (NaMN) and nicotinic acid riboside (NaR). Starting from NAD⁺ or NADH as substrates, we use a combination of three highly overexpressed soluble recombinant enzymes; (a) a NAD+ pyrophosphatase, (b) an NMN deamidase, and (c) a 5'-nucleotidase, to produce these six precursors. Finally, we validate the activity of the enzymatically produced molecules as NAD⁺ enhancers in cell culture.

Nicotinamide Mononucleotide Ameliorates Sleep Deprivation-Induced Gut Microbiota Dysbiosis and Restores Colonization Resistance against Intestinal Infections

Gut microbiota-mediated colonization resistance (CR) is crucial in protecting the host from intestinal infections. Sleep deprivation (SD) is an important contributor in the disturbances of intestinal homeostasis. However, whether and how SD affects host CR remains largely unknown. Here, it is shown that SD impairs intestinal CR in mice, whereas nicotinamide mononucleotide (NMN) supplementation restores it. Microbial diversity and metabolomic analyses suggest that gut microbiota and metabolite profiles in SD-treated mice are highly shaped, whereas NMN reprograms these differences. Specifically, the altered gut microbiota in SD mice further incurs the disorder of secondary bile acids pool accompanied by a decrease in deoxycholic acid (DCA). Conversely, NMN supplementation retakes the potential benefits of DCA, which is associated with specific gut microbiota involved in primary bile acids metabolic flux. In animal models of infection, DCA is effective in preventing and treating bacterial infections when used alone or in combination with antibiotics. Mechanistically, DCA alone disrupts membrane permeability and aggravates oxidative damage, thereby reducing intestinal pathogen burden. Meanwhile, exogenous DCA promotes antibiotic accumulation and destroys oxidant-antioxidant system, thus potentiating antibiotic efficacy. Overall, this work highlights the important roles of gut microbiota and bile acid metabolism in the maintenance of intestinal CR.

Nicotinamide adenine dinucleotide metabolism and arterial stiffness after long-term nicotinamide mononucleotide supplementation: a randomized, double-blind, placebo-controlled trial

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.

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.

Potential Synergistic Supplementation of NAD+ Promoting Compounds as a Strategy for Increasing Healthspan

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.

Effects of nicotinamide mononucleotide on older patients with diabetes and impaired physical performance: A prospective, placebo-controlled, double-blind study

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.

Distribution of Nicotinamide Mononucleotide after Intravenous Injection in Normal and Ischemic Stroke Mice

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.

Nicotinamide Mononucleotide Administration Prevents Doxorubicin-Induced Cardiotoxicity and Loss in Physical Activity in Mice

Doxorubicin (Doxo) is a widely used antineoplastic drug with limited clinical application due to its deleterious dose-related side effects. We investigated whether nicotinamide mononucleotide (NMN) could protect against Doxo-induced cardiotoxicity and physical dysfunction in vivo. To assess the short- and long-term toxicity, two Doxo regimens were tested, acute and chronic. In the acute study, C57BL6/J (B6) mice were injected intraperitoneally (i.p.) once with Doxo (20 mg/kg) and NMN (180 mg/kg/day, i.p.) was administered daily for five days before and after the Doxo injection. In the chronic study, B6 mice received a cumulative dose of 20 mg/kg Doxo administered in fractionated doses for five days. NMN (500 mg/kg/day) was supplied in the mice's drinking water beginning five days before the first injection of Doxo and continuing for 60 days after. We found that NMN significantly increased tissue levels of NAD+ and its metabolites and improved survival and bodyweight loss in both experimental models. In addition, NMN protected against Doxo-induced cardiotoxicity and loss of physical function in acute and chronic studies, respectively. In the heart, NMN prevented Doxo-induced transcriptomic changes related to mitochondrial function, apoptosis, oxidative stress, inflammation and p53, and promyelocytic leukemia nuclear body pathways. Overall, our results suggest that NMN could prevent Doxo-induced toxicity in heart and skeletal muscle.

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

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.

Chronic nicotinamide mononucleotide supplementation elevates blood nicotinamide adenine dinucleotide levels and alters muscle function in healthy older men

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.

Metabolome profiling in the study of aging processes

Aging of a living organism is closely related to systemic metabolic changes. But due to the multilevel and network nature of metabolic pathways, it is difficult to understand these connections. Today, this problem is solved using one of the main approaches of metabolomics — untargeted metabolome profiling. The purpose of this publication is to systematize the results of metabolomic studies based on such profiling, both in animal models and in humans.

Metabolome Profiling in Aging Studies

Organism aging is closely related to systemic metabolic changes. However, due to the multilevel and network nature of metabolic pathways, it is difficult to understand these connections. Today, scientists are trying to solve this problem using one of the main approaches of metabolomics-untargeted metabolome profiling. The purpose of this publication is to review metabolomic studies based on such profiling, both in animal models and in humans. This review describes metabolites that vary significantly across age groups and include carbohydrates, amino acids, carnitines, biogenic amines, and lipids. Metabolic pathways associated with the aging process are also shown, including those associated with amino acid, lipid, and energy metabolism. The presented data reveal the mechanisms of aging and can be used as a basis for monitoring biological age and predicting age-related diseases in the early stages of their development.

Safety evaluation of β-nicotinamide mononucleotide oral administration in healthy adult men and women

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.

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.

Accelerated neuronal aging in vitro ∼melting watch ∼

In developed countries, the aging of the population and the associated increase in age-related diseases are causing major unresolved medical, social, and environmental matters. Therefore, research on aging has become one of the most important and urgent issues in life sciences. If the molecular mechanisms of the onset and progression of neurodegenerative diseases are elucidated, we can expect to develop disease-modifying methods to prevent neurodegeneration itself. Since the discovery of induced pluripotent stem cells (iPSCs), there has been an explosion of disease models using disease-specific iPSCs derived from patient-derived somatic cells. By inducing the differentiation of iPSCs into neurons, disease models that reflect the patient-derived pathology can be reproduced in culture dishes, and are playing an active role in elucidating new pathological mechanisms and as a platform for new drug discovery. At the same time, however, we are faced with a new problem: how to recapitulate aging in culture dishes. It has been pointed out that cells differentiated from pluripotent stem cells are juvenile, retain embryonic traits, and may not be fully mature. Therefore, attempts are being made to induce cell maturation, senescence, and stress signals through culture conditions. It has also been reported that direct conversion of fibroblasts into neurons can reproduce human neurons with an aged phenotype. Here, we outline some state-of-the-art insights into models of neuronal aging in vitro. New frontiers in which stem cells and methods for inducing differentiation of tissue regeneration can be applied to aging research are just now approaching, and we need to keep a close eye on them. These models are forefront and intended to advance our knowledge of the molecular mechanisms of aging and contribute to the development of novel therapies for human neurodegenerative diseases associated with aging.

Separation of nicotinamide metabolites using a PBr column packed with pentabromobenzyl group modified silica gel

Nicotinamide adenine dinucleotide, a coenzyme involved in the activation of sirtuins, contributes to various regulations in vivo. However, highly hydrophilic nicotinamide metabolites are difficult to separate by high-performance liquid chromatography (HPLC) using octadecyl (C₁₈) columns, which operate via hydrophobic interaction. PBr columns packed with silica gel modified with the pentabromobenzyl group having strong dispersion forces show good retention ability for various highly hydrophilic compounds. Additionally, the peak shape obtained with the PBr column did not collapse like that of the HILIC column, even when a large amount of water was injected. Separation of 11 highly hydrophilic nicotinamide metabolites using a PBr column under simple conditions resulted in baseline separation, but separation on a C₁₈ column was not complete. The peak shape for each compound was better than that in previous studies. Furthermore, the separation of nicotinamide metabolites in tomato using a PBr column enable a more sensitive detection than that using a C₁₈ column. SUBJECT CATEGORY: Chromatographic Technique.

Clinical Trials Targeting Aging

The risk of morbidity and mortality increases exponentially with age. Chronic inflammation, accumulation of DNA damage, dysfunctional mitochondria, and increased senescent cell load are factors contributing to this. Mechanistic investigations have revealed specific pathways and processes which, proposedly, cause age-related phenotypes such as frailty, reduced physical resilience, and multi-morbidity. Among promising treatments alleviating the consequences of aging are caloric restriction and pharmacologically targeting longevity pathways such as the mechanistic target of rapamycin (mTOR), sirtuins, and anti-apoptotic pathways in senescent cells. Regulation of these pathways and processes has revealed significant health- and lifespan extending results in animal models. Nevertheless, it remains unclear if similar results translate to humans. A requirement of translation are the development of age- and morbidity associated biomarkers as longitudinal trials are difficult and not feasible, practical, nor ethical when human life span is the endpoint. Current biomarkers and the results of anti-aging intervention studies in humans will be covered within this paper. The future of clinical trials targeting aging may be phase 2 and 3 studies with larger populations if safety and tolerability of investigated medication continues not to be a hurdle for further investigations.

Nicotinamide mononucleotide ameliorates acute lung injury by inducing mitonuclear protein imbalance and activating the UPRmt

Mitochondria need to interact with the nucleus under homeostasis and stress to maintain cellular demands and nuclear transcriptional programs. Disrupted mitonuclear interaction is involved in many disease processes. However, the role of mitonuclear signaling regulators in endotoxin-induced acute lung injury (ALI) remains unknown. Nicotinamide adenine dinucleotide (NAD⁺) is closely related to mitonuclear interaction with its central role in mitochondrial metabolism. In the current study, C57BL/6J mice were administrated with lipopolysaccharide 15 mg/kg to induce endotoxin-induced ALI and investigated whether the NAD⁺ precursor nicotinamide mononucleotide (NMN) could preserve mitonuclear interaction and alleviate ALI. After pretreatment with NMN for 7 days, NAD⁺ levels in the mitochondrial, nucleus, and total intracellular were significantly increased in endotoxemia mice. Moreover, supplementation of NMN alleviated lung pathologic injury, reduced ROS levels, increased MnSOD activities, mitigated mitochondrial dysfunction, ameliorated the defects in the nucleus morphology, and these cytoprotective effects were accompanied by preserving mitonuclear interaction (including mitonuclear protein imbalance and the mitochondrial unfolded protein response, UPR^mt). Furthermore, NAD⁺-mediated mitonuclear protein imbalance and UPR^mt are probably regulated by deacetylase Sirtuin1 (SIRT1). Taken together, our results indicated that NMN pretreatment ameliorated ALI by inducing mitonuclear protein imbalance and activating the UPR^mt in an SIRT1-dependent manner.

The effects of nicotinamide adenine dinucleotide in cardiovascular diseases: Molecular mechanisms, roles and therapeutic potential

Recently, cardiovascular diseases (CVDs) were identified as the leading cause of mortality, imposing a heavy burden on health care systems and the social economy. Nicotinamide adenine dinucleotide (NAD⁺), as a pivotal co-substrate for a range of different enzymes, is involved in many signal transduction pathways activated in CVDs. Emerging evidence has shown that NAD⁺ can exert remediating effects on CVDs by regulating metabolism, maintaining redox homeostasis and modulating the immune response. In fact, NAD⁺ might delay ageing through sirtuin and non-sirtuin pathways and thus contribute to interventions for age-related diseases such as CVDs. Considering that robust clinical studies of NAD⁺ are ongoing, we discuss current challenges and the future translational potential of NAD⁺ based on existing studies and our understanding. Despite some remaining gaps in its clinical application, NAD⁺ has been shown to have broad prospects and pan-effects, making it a suitable prophylactic drug for CVDs.

Metformin, Rapamycin, or Nicotinamide Mononucleotide Pretreatment Attenuate Cognitive Impairment After Cerebral Hypoperfusion by Inhibiting Microglial Phagocytosis

Vascular cognitive impairment (VCI) is the second leading form of dementia after Alzheimer's disease (AD) plaguing the elder population. Despite the enormous prevalence of VCI, the biological basis of this disease has been much less well-studied than that of AD, with no specific therapy currently existing to prevent or treat VCI. As VCI mainly occurs in the elderly, the role of anti-aging drugs including metformin, rapamycin, and nicotinamide mono nucleotide (NMN), and the underlying mechanism remain uncertain. Here, we examined the role of metformin, rapamycin, and NMN in cognitive function, white matter integrity, microglial response, and phagocytosis in a rat model of VCI by bilateral common carotid artery occlusion (BCCAO). BCCAO-induced chronic cerebral hypoperfusion could cause spatial working memory deficits and white matter lesions (WMLs), along with increasing microglial activation and phagocytosis compared to sham-operated rats. We found the cognitive impairment was significantly improved in BCCAO rats pretreated with these three drugs for 14 days before BCCAO compared with the vehicle group by the analysis of the Morris water maze and new object recognition tests. Pretreatment of metformin, rapamycin, or NMN also increased myelin basic protein (MBP, a marker for myelin) expression and reduced SMI32 (a marker for demyelinated axons) intensity and SMI32/MBP ratio compared with the vehicle group, suggesting that these drugs could ameliorate BCCAO-induced WMLs. The findings were confirmed by Luxol fast blue (LFB) stain, which is designed for staining myelin/myelinated axons. We further found that pretreatment of metformin, rapamycin, or NMN reduced microglial activation and the number of M1 microglia, but increased the number of M2 microglia compared to the vehicle group. Importantly, the number of MBP⁺/Iba1⁺/CD68⁺ microglia was significantly reduced in the BCCAO rats pretreated with these three drugs compared with the vehicle group, suggesting that these drugs suppress microglial phagocytosis. No significant difference was found between the groups pretreated with metformin, rapamycin, or NMN. Our data suggest that metformin, rapamycin, or NMN could protect or attenuate cognitive impairment and WMLs by modifying microglial polarization and inhibiting phagocytosis. The findings may open a new avenue for VCI treatment.

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

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).

NAD+ and Vascular Dysfunction: From Mechanisms to Therapeutic Opportunities

Nicotinamide adenine dinucleotide (NAD+) is an essential and pleiotropic coenzyme involved not only in cellular energy metabolism, but also in cell signaling, epigenetic regulation, and post-translational protein modifications. Vascular disease risk factors are associated with aberrant NAD+ metabolism. Conversely, the therapeutic increase of NAD+ levels through the administration of NAD+ precursors or inhibitors of NAD+-consuming enzymes reduces chronic low-grade inflammation, reactivates autophagy and mitochondrial biogenesis, and enhances oxidative metabolism in vascular cells of humans and rodents with vascular pathologies. As such, NAD+ has emerged as a potential target for combatting age-related cardiovascular and cerebrovascular disorders. This review discusses NAD+-regulated mechanisms critical for vascular health and summarizes new advances in NAD+ research directly related to vascular aging and disease, including hypertension, atherosclerosis, coronary artery disease, and aortic aneurysms. Finally, we enumerate challenges and opportunities for NAD+ repletion therapy while anticipating the future of this exciting research field, which will have a major impact on vascular medicine.

Aging of the Peritoneal Dialysis Membrane

Long-term peritoneal dialysis as currently performed, causes structural and functional alterations of the peritoneal dialysis membrane. This decay is brought about by the continuous exposure to commercially available glucose-based dialysis solutions. This review summarizes our knowledge on the peritoneum in the initial phase of PD, during the first 2 years and the alterations in function and morphology in long-term PD patients. The pseudohypoxia hypothesis is discussed and how this glucose-induced condition can be used to explain all peritoneal alterations in long-term PD patients. Special attention is paid to the upregulation of hypoxia inducing factor-1 and the subsequent stimulation of the genes coding for glucose transporter-1 (GLUT-1) and the growth factors transforming growth factor-β (TGFβ), vascular endothelial growth factor (VEGF), plasminogen growth factor activator inhibitor-1 (PAI-1) and connective tissue growth factor (CTGF). It is argued that increased pseudohypoxia-induced expression of GLUT-1 in interstitial fibroblasts is the key factor in a vicious circle that augments ultrafiltration failure. The practical use of the protein transcripts of the upregulated growth factors in peritoneal dialysis effluent is considered. The available and developing options for prevention and treatment are examined. It is concluded that low glucose degradation products/neutral pH, bicarbonate buffered solutions with a combination of various osmotic agents all in low concentration, are currently the best achievable options, while other accompanying measures like the use of RAAS inhibitors and tamoxifen may be valuable. Emerging developments include the addition of alanyl glutamine to the dialysis solution and perhaps the use of nicotinamide mononucleotide, available as nutritional supplement.

NAD+ Precursors Repair Mitochondrial Function in Diabetes and Prevent Experimental Diabetic Neuropathy

Axon degeneration in diabetic peripheral neuropathy (DPN) is associated with impaired NAD+ metabolism. We tested whether the administration of NAD+ precursors, nicotinamide mononucleotide (NMN) or nicotinamide riboside (NR), prevents DPN in models of Type 1 and Type 2 diabetes. NMN was administered to streptozotocin (STZ)-induced diabetic rats and STZ-induced diabetic mice by intraperitoneal injection at 50 or 100 mg/kg on alternate days for 2 months. mice The were fed with a high fat diet (HFD) for 2 months with or without added NR at 150 or 300 mg/kg for 2 months. The administration of NMN to STZ-induced diabetic rats or mice or dietary addition of NR to HFD-fed mice improved sensory function, normalized sciatic and tail nerve conduction velocities, and prevented loss of intraepidermal nerve fibers in skin samples from the hind-paw. In adult dorsal root ganglion (DRG) neurons isolated from HFD-fed mice, there was a decrease in NAD+ levels and mitochondrial maximum reserve capacity. These impairments were normalized in isolated DRG neurons from NR-treated mice. The results indicate that the correction of NAD+ depletion in DRG may be sufficient to prevent DPN but does not significantly affect glucose tolerance, insulin levels, or insulin resistance.