Fig. 3
NAD-mediated metabolic map. NAD is synthesized by two main pathways, including de-novo and salvage pathways. NAM nicotinamide, Npt nicotinic acid phosphoribosyltransferase, 5′-NT 5′-nucleotidase, NaMN nicotinic acid mononucleotide, NR nicotinamide riboside, NMN nicotinamide mononucleotide, iNampt intracellular NAM phosphoribosyl transferase (iNampt), NRK nicotinamide riboside kinases, Nmnat nicotinamide mononucleotide adenylyl transferases, NADS NAD synthetase, NAR nicotinic acid riboside, 5′-NT 5′-nucleotidase, Aox aldehyde oxidase. The two end-products of Aox, N1-methyl-2-pyridone-5-carboxamide (2py) and N1-methyl-4-pyridone-3-carboxamide (4py), together with MNA are excreted in the urine. Nnmt (nicotinamide N-methyltransferase) converts NAM to N1-methylniacinamide (MNA). NAM is also converted by CYP2E1 (Cytochrome P450 2E1) to NNO (NAM N-oxide), which is also eliminated in the urine