Differential effects of 7,8-benzoflavone on polycyclic aromatic hydrocarbon dependent mutagenesis and cytotoxicity in a keratinocyte cell-mediated mutation assay.

A murine keratinocyte cell-mediated mutagenesis assay was used to examine the effects of 7,8-benzoflavone (7,8-BF) on the metabolic activation of 7,12-dimethylbenz[a]anthracene (DMBA) and benzo[a]pyrene (BP) to mutagenic and cytotoxic metabolites. DMBA-dependent mutagenesis and cytotoxicity were strongly and coordinately inhibited by 7,8-BF in a concentration-dependent manner. BP-dependent mutagenesis was also strongly inhibited by 7,8-BF in a concentration-dependent manner; whereas BP-dependent cytotoxicity was relatively unaffected by 7,8-BF. Maximum inhibition of DMBA- and BP-dependent mutagenesis occurred when the cultured keratinocytes were treated with 7,8-BF immediately prior to the addition of BP or DMBA.