Induction of DNA-lesions in freshly isolated rat hepatocytes by different genotoxins and their reduction by lignin given either as a dietary component or in in vitro conditions.

The aim of our investigation was to verify the protective effect of lignin on DNA in rat hepatocytes damaged by 3 different genotoxins attacking DNA in a different manner. Hydrogen peroxide was used for induction of direct single strand breaks of DNA, visible light-excited methylene blue for induction of oxidized DNA lesions and 1,2-dibromo-3-chloropropane for induction of alkali-labile DNA lesions. Hepatocytes were pre-treated with lignin either immediately after isolation, i.e., in in vitro conditions, or the hepatocytes were isolated from rats fed a lignin enriched diet for 21 days (ex vivo conditions). The protective effect of lignin applied to hepatocytes by the first or by the second approach was tested on the level of DNA using classical and modified single cell gel electrophoresis (SCGE). We found that lignin applied by each way significantly reduced the level of direct DNA strand breaks induced by H2O2, alkali-labile sites of DNA induced by DBCP as well as oxidative DNA lesions induced by visible light-excited methylene blue. These results confirm that lignin represents a very important micronutrient in our vegetable food, protecting DNA against damaging effects of different genotoxicants.