NAD+

Overview

NAD+ (nicotinamide adenine dinucleotide, oxidised form) is a ubiquitous coenzyme present in every living cell, essential for over 500 enzymatic reactions. It functions as a critical electron carrier in mitochondrial oxidative phosphorylation and serves as a substrate for key regulatory enzymes including sirtuins (SIRT1-7), PARPs (poly-ADP-ribose polymerases), and CD38/CD157 ectoenzymes. Intracellular NAD+ levels decline with age — by approximately 50% between ages 40 and 60 — making NAD+ metabolism one of the most active areas of ageing and longevity research.

Mechanism of Action

NAD+ participates in cellular energy metabolism as a hydride acceptor in glycolysis, the TCA cycle, and the electron transport chain (as NADH donates electrons to Complex I). Beyond its metabolic role, NAD+ is consumed as a substrate by sirtuins to deacetylate target proteins — a reaction that links metabolic status to epigenetic regulation. PARP1 and PARP2 consume NAD+ during DNA damage repair. CD38, the primary NAD+ consumer in mammalian tissues, cleaves NAD+ to produce cyclic ADP-ribose and nicotinamide. This consumption-based regulation makes NAD+ a central node connecting metabolism, DNA repair, and gene expression.

Research Applications

• Sirtuin biology and epigenetic regulation research
• Mitochondrial electron transport and bioenergetics
• DNA damage repair and PARP enzyme studies
• Age-related NAD+ decline and longevity research
• CD38/NAD+ metabolism and immune cell biology