Role of Nicotinamide in DNA Damage, Mutagenesis, and DNA Repair
Figure 2
The simplified pathways for nicotinamide, niacin, , and PARP-1 metabolism. Dietary nicotinamide, niacin, and tryptophan are precursors for the synthesis of , essential in ATP production and PARP-1 activation. Nicotinamide can be converted to niacin by bacterial nicotinamidase in the intestinal lumen. PARP-1 is activated by DNA strand breaks, cleaving into nicotinamide and ADP-ribose. Poly(ADP-ribose) glycohydrolase (PARG) reactivates PARP-1 by removing poly(ADP-ribose)polymers, allowing for continuous utilization. Figure is adapted from Jacobson et al., in 1995 [6] and Meyer-Ficca et al., in 2004 [12].