NAD+

NAD+ (nicotinamide adenine dinucleotide, oxidized form) is a pyridine dinucleotide coenzyme present in all living cells, where it serves as an essential electron carrier in the core reactions of cellular energy metabolism and as a critical substrate for a growing class of enzymes that regulate DNA repair, gene expression, and longevity signaling. In its oxidized form (NAD+), the molecule accepts electrons from metabolic intermediates in glycolysis, the TCA cycle, and beta-oxidation, becoming reduced to NADH; this NAD+/NADH redox cycling is the central mechanism by which cells extract energy from macronutrients and drive the mitochondrial electron transport chain to synthesize ATP.

Beyond its redox role, NAD+ is the sole substrate for several enzymatic classes of growing research importance. Sirtuins (SIRT1–SIRT7) are NAD+-dependent deacylases that link cellular NAD+ availability to gene silencing, mitochondrial biogenesis (SIRT1/SIRT3-PGC-1α axis), DNA repair coordination (SIRT1, SIRT6), and metabolic adaptation. SIRT1 and SIRT3 have been extensively studied in the context of caloric restriction and longevity in model organisms, and their dependence on NAD+ has made intracellular NAD+ availability a key variable in aging-biology research. PARP1 and PARP2 (poly-ADP-ribose polymerases) consume NAD+ at high rates during DNA damage responses, a consumption that becomes pathologically excessive during severe genotoxic stress and has led researchers to study NAD+ replenishment as a strategy for preserving sirtuin activity during high-PARP activation scenarios. CD38, a cyclic ADP-ribose synthase expressed widely in immune and muscle tissue, is the largest consumer of cellular NAD+ in many tissues and is studied as a driver of the age-related NAD+ decline.

Intracellular NAD+ concentrations have been consistently documented to decline with age in rodents and in human tissue studies. This decline appears to be driven by accumulating CD38 activity, declining biosynthetic capacity, and increased PARP activation from age-associated DNA damage accumulation. The consequences in research models include impaired mitochondrial function, reduced sirtuin activity, and compromised DNA repair — a cluster of effects that has made NAD+ restoration a central hypothesis in the biology of aging. Precursor supplementation with NMN (nicotinamide mononucleotide) and NR (nicotinamide riboside) is the most studied route for increasing intracellular NAD+. Direct NAD+ administered exogenously faces cell-membrane permeability challenges and requires extracellular ectonucleotidase processing for cellular uptake. Peptides.SO tracks 65 NAD+ listings from 61 distinct suppliers, all in stock, with a wide pricing range from $0.08 to $279.99 and a median of $44.99 per listing unit.

Potential Research Applications: NAD+/NADH redox flux and mitochondrial electron transport chain efficiency studies SIRT1/SIRT3-PGC-1α axis activation and mitochondrial biogenesis research in aging models PARP1/2-dependent DNA repair and NAD+ depletion during genotoxic stress CD38-mediated NAD+ catabolism and its role in immune and age-related NAD+ decline Caloric restriction mimicry and NAD+-dependent longevity pathway research Comparative assessment of direct NAD+ vs NMN vs NR supplementation in preclinical models Cellular energy metabolism profiling in ATP synthesis and oxidative phosphorylation models NAD+-dependent metabolite signaling (cADPR, NAADP) in calcium signaling research NF-κB signaling suppression and anti-inflammatory effects via SIRT1-NF-κB interaction

Marketplace Snapshot (September 2026, Peptides.SO listings data): Tracked listings: 65 from 61 distinct suppliers (65 in stock) Median listing price: $44.99 (interquartile range $0.20 – $85.00 per listing unit) Lowest verified price: $0.08 per unit — reflects high-volume or bulk formulations Note: NAD+ pricing varies substantially by formulation (powder vs lyophilized vs injectable-grade), quantity, and purity grade. Research-grade NAD+ suitable for enzymatic assays or cell-culture supplementation studies typically runs $15–$80 per gram depending on purity documentation. Injectable-grade preparations carry a premium due to additional sterility testing requirements. The wide price range (61 distinct suppliers) gives researchers extensive comparison data via the live comparison table on this page.

Frequently Asked Questions: Q: What is the difference between NAD+ and NADH, and which is relevant for research supplementation? A: NAD+ is the oxidized form that accepts electrons; NADH is the reduced form that donates electrons to complex I of the electron transport chain. In research contexts, NAD+ is the focus of sirtuin and PARP biology because sirtuins and PARPs consume NAD+ as a substrate, not NADH. Research supplementation studies typically use NAD+ directly or its precursors (NMN, NR) to study restoration of NAD+ pool size rather than altering the NAD+/NADH ratio per se.

Q: Why do intracellular NAD+ levels decline with age? A: Three mechanisms are consistently cited: first, declining activity of biosynthetic enzymes (particularly NAMPT in the salvage pathway); second, increased consumption by CD38, a NAD+-hydrolyzing enzyme whose expression increases with age and inflammatory signaling; third, chronic low-grade genotoxic stress increasing baseline PARP1/2 activation and NAD+ consumption. The net result is that in many tissues (liver, muscle, brain), intracellular NAD+ concentrations in old rodents are 40–60% lower than in young controls.

Q: How does NAD+ affect sirtuin activity in aging research? A: Sirtuins require NAD+ as a co-substrate — they cleave the nicotinamide moiety from NAD+ as part of each catalytic cycle of protein deacylation. Because Km values for NAD+ are close to physiological NAD+ concentrations in some tissues, a decline in NAD+ produces a roughly proportional decline in sirtuin activity rather than an on/off switch. This makes NAD+ availability a rheostat for sirtuin-regulated processes including mitochondrial biogenesis, metabolic gene silencing, and DNA repair coordination.

Q: What distinguishes 6-Biotin-17-NAD from standard NAD+ in research use? A: 6-Biotin-17-NAD is a biotinylated NAD+ analog used as a tool compound for detecting PARP and sirtuin activity: the biotin handle on the adenine ring allows ADP-ribosylation products or sirtuin deacylation products to be captured on streptavidin and visualized or quantified by immunoblot or ELISA. It is a mechanistic probe compound rather than a supplementation tool.

Q: How many suppliers offer NAD+ for research purchase, and what are typical prices? A: Peptides.SO tracks 65 listings from 61 distinct suppliers. The market is highly fragmented, reflecting NAD+'s status as a commodity-tier research chemical. Research-grade powder typically runs $15–$80 per gram; injectable-grade or COA-verified preparations with mass-spec confirmation carry a premium up to $200+ per gram.

Q: Is NAD+ approved for human use? A: NAD+ is generally recognized as safe (GRAS) as a dietary ingredient in the US when formulated as a dietary supplement. However, injectable-grade NAD+ is not approved as a drug. Research material listed on this platform is sold strictly for laboratory investigation and is not for human consumption in injectable form.

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Cited Research: Imai S, Guarente L. NAD+ and sirtuins in aging and disease. Trends Cell Biol. 2014;24(8):464-471. PubMed PMID: 24786309. Camacho-Pereira J, Tarragó MG, Chini CCS, et al. CD38 Dictates Age-Related NAD Decline and Mitochondrial Dysfunction through an SIRT3-Dependent Mechanism. Cell Metab. 2016;23(6):1127-1139. PubMed PMID: 27304511. Yoshino J, Baur JA, Imai SI. NAD+ Intermediates: The Biology and Therapeutic Potential of NMN and NR. Cell Metab. 2018;27(3):513-528. PubMed PMID: 29249689.

For laboratory research only. Not for human or veterinary use, diagnosis, treatment, cure, or prevention of any disease. THIS PRODUCT IS NOT FOR HUMAN CONSUMPTION.