Effects of organosulfurs, isothiocyanates and vitamin C towards hydrogen peroxide-induced oxidative DNA damage (strand breaks and oxidized purines/pyrimidines) in human hepatoma cells

The aim of this study was to evaluate the effects of organosulfurs, isothiocyanates and vitamin C towards hydrogen peroxide-induced DNA damage (DNA strand breaks and oxidized purines/pyrimidines) in human hepatoma cells (HepG2), using the Comet assay. Treatment with hydrogen peroxide (H2O2) increased the levels of DNA strand breaks and oxidized purine and pyrimidine bases, in a concentration and time dependent manner. Organosulfur compounds (OSCs) reduced DNA strand breaks induced by H2O2. In addition, OSCs also decreased the levels of oxidized pyrimidines. However, none of the OSCs tested reduced the levels of oxidized purines. Isothiocyanates compounds (ITCs) and vitamin C showed protective effects towards H2O2-induced DNA strand breaks and oxidized purine and pyrimidine bases. The results indicate that removal of oxidized purine and pyrimidine bases by ITCs was more efficient than by OSCs and vitamin C. Our findings suggest that OSCs, ITCs and vitamin C could exert their protective effects towards H2O2-incluced DNA strand breaks and oxidative DNA damage by the free radical-scavenging efficiency of these compounds. (c) 2007 Elsevier Ireland Ltd. All rights reserved.