Handbook of Vitamin C Research

Vitamin C Protects from Oxidative DNA Damage… 103Figure 7.Figure 7. Effect of vitamin C on (A) NDMA, (B) NPYR, (C) NPIP and (D) NDBA-induced oxidativeDNA damage in human HepG2 cells. C1, ( ) HepG2 cells treated with N-Nitrosamines in presence ofFpg enzyme. ( ) HepG2 cells simultaneously treated with N-Nitrosamines and vitamin C in presenceof Fpg enzyme. Asterisks indicate significant difference from control ***p 0.001, **p 0.01 and *p0.05.Oxidative DNA Damage Induction by a Simultaneous Treatment of NPIP orNDBA and Vitamin C in Combination with ItcsThe effect of AITC, PEITC or I3C (0.1, 0.5 and 1 M) alone on NPIP or NDBA-inducedoxidative DNA damage in HepG2 cells incubated with Fpg enzyme was previously evaluatedin our laboratory [70]. The results obtained in these experiments showed that the higherprotective effect of ITCs alone towards oxidative DNA damage induced by NPIP and NDBAwas observed at 1 and 0.1 M, respectively. Thus, in the present chapter it has been presentedthe protective effect of ITCs alone or in combination with vitamin C (10 M) at theseconcentrations.Figure 8 A shows the protective effect of AITC, PEITC or I3C alone on NPIP or NDBAinducedoxidative DNA damage in HepG2 cells incubated with Fpg enzyme. At theconcentrations tested, AITC did not attenuate the NPIP or NDBA-induced oxidative DNAdamage. However, the oxidative DNA damage provoked by NPIP in HepG2 cells wasslightly prevented by PEITC and I3C at 1 M (26 and 28%, respectively), whereas the effectof NDBA was attenuated by 27 and 26% with lower concentrations of PEITC and I3C (0.1M), respectively.The protective effect of AITC, PEITC or I3C in combination with vitamin C (10 M) onNPIP or NDBA-induced oxidative DNA damage in HepG2 cells incubated with Fpg enzymeis shown in Figure 8 B. A significant reduction (63-25%) on NPIP and NDBA-induced