Nicotinamide adenine dinucleotide biosynthesis pathway (NAD+ biosynthesis pathway)

The nicotinamide adenine dinucleotide biosynthesis pathway refers collectively to the metabolic routes by which cells generate nicotinamide adenine dinucleotide (NAD+), an essential coenzyme involved in redox reactions, energy production, DNA repair, epigenetic regulation, and cell signaling. There are three main routes for its synthesis: 1. The de novo kynurenine pathway from tryptophan. 2. The Preiss–Handler pathway from dietary nicotinic acid. 3. The salvage pathways from recycled nicotinamide or other vitamin B3 derivatives such as nicotinamide riboside. Key enzymatic steps involve conversion of these precursors into intermediates like NMN and NaMN before final assembly into NAD+. Enzymes such as NAMPT play rate-limiting roles in these processes. Disruption or enhancement of this network has been implicated in aging processes, cancer metabolism, neurodegeneration, cardiovascular health, and more—making individual components attractive therapeutic targets rather than the entire "pathway" itself.[1][2][3][4][5] Note: "Nicotinamide adenine dinucleotide biosynthesis pathway" is not a single molecular target but rather a collection of interconnected biochemical reactions involving multiple distinct proteins/enzymes; thus it is not considered a canonical therapeutic target per se.[4]

Other names

NAD+ biosynthetic pathwaysNAD+ metabolismNicotinamide adenine dinucleotide synthesisNAD salvage pathway (refers to a major sub-pathway)Preiss–Handler pathway (sub-pathway)Kynurenine pathway (de novo sub-pathway)

Mechanisms relate to modulation of enzyme activity within the pathway or supplementation of precursors, including: - Inhibition of key enzymes such as nicotinamide phosphoribosyltransferase in cancer therapy research - Supplementation with precursors to boost cellular NAD+ levels for metabolic or anti-aging effects