Molecular mechanisms of aromatic amine-induced reactive oxygen species-mediated genotoxicity

We studied aromatic amine mediated production and genotoxicity of reactive oxygen species (ROS) employing Ames Salmonella/microsome mutagenicity assay using TA102 tester strain, thobarbituric acid reactive substance (TBARS) assay for lipidperoxidation. 4-Aminobiphenyl (4-Ab), benzidine (Bz) and some of the benzidine congeners were mutagenic on TA102 in the presence of S9. 4, 4'-Dinitro-2-biphenylamine was mutagenic to TA102 in the absence of S9. Incorporation of antioxidants and metal chelators such as superoxide dismutase (SOD), catalase (CAT), butylated hydroxytolune (BHT), and ethylenediaminetetraacetate (EDTA) into the test system decreased the mutagenicity of 4-Ab and Bz. Both 4-Ab and Bz induced lipidperoxidation in time dependent manner in TBARS assay.; We investigated the possibility of iron (II) and NADPH generating system (NGS) mediated oxidation of Bz and 4-Ab to produce ROS employing Ames Salmonella/microsome mutagenicity assay using TA98, TA100, and TA102 tester strains, and thobarbituric acid reactive substance (TBARS) assay to test lipidperoxidation. We also evaluated the possibility of DNA strand breaks using double stranded circular plasmid DNA employing agarose gel electrophoresis. Both Bz and 4-Ab were mutagenic in all the three tester strains and also induced lipidperoxidation in the presence of iron (II) and NGS and in the absence of S9. Incorporation of SOD, CAT, EDTA and desferroxamine (DF) (an iron chelator) not only decreased the mutagenicity of Bz and 4-Ab but also significantly inhibited the lipidperoxidation induced by Bz and 4-Ab. Both Bz and 4-Ab induced DNA strand breaks in the presence of iron (II).; To evaluate the antimutagenic effect of various dietary plant polyphenols on Bz-induced mutations and lipidperoxidation, we have incorporated various dietary polyphenols in combination with Bz into Ames assay using TA102 tester strain and also in TBARS assay. The plant polyphenols were categorized according to their antimutagenic effect on Bz-induced mutagencity and lipidperoxidation into "strongly, moderately, weakly inhibitory, and not inhibitory" (see chapter-5). Isoliquirtigenin, quercetin dihydrate and rhein were found to be mutagenic in tester strain TA102.; In conclusion, both Bz and 4-Ab could produce ROS and thus not only induce mutations in Salmonella tester strains and also cause lipidperoxidation in the presence of S9, or iron and NGS.