DNA damage induced by N-nitrosodibenzylamine and N-nitroso-alpha-acetoxybenzyl-benzylamine in mammalian cell systems and in vivo.

N-nitrosodibenzylamine (NDBzA) and N-nitroso-alpha-acetoxybenzyl-benzylamine (alpha-acetoxy-NDBzA) were tested for induction of DNA single-strand breaks (SSBs) in V 79 Chinese hamster cells (V 79 cells) and isolated rat hepatocytes. The alkaline elution assay was used for the detection of DNA strand breaks. Treatment of V 79 cells with alpha-acetoxy-NDBzA effectively increased the rate of DNA SSBs, while with NDBzA, no DNA-damaging activity was detectable. Both substances produced significant DNA damage in rat hepatocytes. Interestingly, NDBzA was able to induce SSBs at significantly lower concentrations than alpha-acetoxy-NDBzA. The possible reasons for these findings are discussed. In contrast to these in vitro results, NDBzA exhibited very weak in vivo activity.