NAD+

• Longevity and aging research
• Mitochondrial-pathway research
• Redox and metabolism studies
• Cellular energy research

Supplied as a lyophilized powder for stability.

NAD⁺ is one of the most extensively characterised coenzymes in biochemistry, first described in the early twentieth century in the context of fermentation. It occupies a central position in intermediary metabolism: as an electron acceptor it links glycolysis, the tricarboxylic acid cycle, and oxidative phosphorylation, and as a consumed substrate it supports a separate class of signalling enzymes.

Cellular NAD⁺ pools are maintained by three routes: de-novo synthesis from tryptophan via the kynurenine pathway, the Preiss–Handler pathway from nicotinic acid, and the salvage pathway that recycles nicotinamide through nicotinamide phosphoribosyltransferase (NAMPT). The salvage route accounts for the majority of turnover in most mammalian cell types, which is why NAMPT activity is a frequent variable in experimental designs.

Reported declines in tissue NAD⁺ concentration in aged animal models, and the consequences of those declines for sirtuin and PARP activity, have made NAD⁺ biology an active area of preclinical investigation.

NAD⁺ is a dinucleotide: two nucleotides joined through their phosphate groups. One carries an adenine base, the other a nicotinamide moiety, each attached to a ribose sugar and bridged by a pyrophosphate linkage.

Redox chemistry occurs at the nicotinamide ring. Reduction adds a hydride to the C4 position of the pyridine ring to give NADH, a change that produces the characteristic absorbance at 340 nm used to follow the reaction. In its signalling role the molecule is instead cleaved at the glycosidic bond between nicotinamide and ribose, releasing nicotinamide and transferring the ADP-ribose portion — a consumptive reaction, in contrast to the catalytic cycling of the redox role.

Regulation of Cellular Energy Metabolism

In its redox capacity NAD⁺ accepts electrons from catabolic reactions and delivers them, as NADH, to complex I of the electron transport chain. The ratio of free NAD⁺ to NADH is therefore a determinant of flux through glycolysis and the TCA cycle, and is widely used in vitro as a readout of metabolic state. Experimental manipulation of this ratio alters the activity of dehydrogenases at several control points.

DNA-Maintenance Signalling and Genomic Stability

PARP enzymes, principally PARP1, consume NAD⁺ to build poly(ADP-ribose) chains on target proteins at sites of DNA strand breaks, recruiting repair machinery. Because this consumes the same pool that supports redox metabolism and sirtuin activity, sustained PARP activation in damage models has been reported to lower available NAD⁺ and produce measurable competition between these pathways.

Epigenetic and Stress Signalling via Sirtuins

Sirtuins catalyse NAD⁺-dependent removal of acyl groups from lysine residues on histones and other substrates, coupling the deacylation reaction to NAD⁺ cleavage. Their strict dependence on NAD⁺ availability makes them a proposed link between the metabolic state of a cell and transcriptional regulation. Reported in-vitro substrates span mitochondrial enzymes, transcription factors, and chromatin, with subcellular distribution differing across the seven mammalian isoforms.

Neuro-Metabolic Models

Axonal degeneration models have identified NAD⁺ metabolism, and the enzyme SARM1 in particular, as a determinant of degeneration following injury in cultured neurons. This work is a substantial area of current preclinical research and is cited here only to describe the experimental context in which NAD⁺ is studied.

NAD⁺ is unusual in serving two distinct biochemical roles: a recycled electron carrier in metabolism, and a consumed substrate for enzymes that regulate DNA repair and gene expression. This dual character is what makes it a recurring variable across metabolic, genomic-stability, and cellular-ageing research. The material offered here is supplied for such in-vitro laboratory work only.

1. Imai S, Guarente L. NAD⁺ and sirtuins in aging and disease. Trends in Cell Biology, 2014.
2. Verdin E. NAD⁺ in aging, metabolism, and neurodegeneration. Science, 2015.
3. Cantó C, Menzies KJ, Auwerx J. NAD⁺ metabolism and the control of energy homeostasis. Cell Metabolism, 2015.
4. Rajman L, Chwalek K, Sinclair DA. Therapeutic potential of NAD-boosting molecules: the in vivo evidence. Cell Metabolism, 2018.
5. Covarrubias AJ, Perrone R, Grozio A, Verdin E. NAD⁺ metabolism and its roles in cellular processes during ageing. Nature Reviews Molecular Cell Biology, 2021.