Nicotinic acid (NA) is a coenzyme in cellular redox reactions,and is an essential component of metabolic pathways in all living cells. NAPRT1 (Nicotinate phosphoribosyltransferase) is essential for increasing cellular NAD levels and,thus,to prevent oxidative stress of cells. NAPRT1 converts Nicotinic acid (NA; niacin) to NA mononucleotide (NaMN),which is then converted to NA adenine dinucleotide (NaAD),and finally to nicotinamide adenine dinucleotide (NAD).