Possible involvement of a vicinal, non-bay-region dihydrodiol-epoxide in the activation of dibenzo[a,e]fluoranthene into bacterial mutagens.

Dibenzo[a,e]fluoranthene, its 7-hydroxy, 3,4- and 12,13-dihydrodiol metabolic derivatives as well as three synthetic, structurally related hydrocarbons, were tested for mutagenicity towards Salmonella typhimurium TA100 strain in the presence of 3-methylcholanthrene-treated rat and mouse liver post-mitochondrial supernatants. Of these compounds, the 12,13-dihydrodiol showed the highest activity, being 6-10 times more mutagenic than the parent compound. Our data, in conjunction with those of previous studies on the liver microsomal metabolism and DNA binding of dibenzo[a,e]fluoranthene and its dihydrodiols, indicate that activation of dibenzo[a,e]fluoranthene to bacterial mutagens may occur predominantly through a vicinal, non-bay-region 12,13-dihydrodiol epoxide.