Identification of mutagenic dihydrodiols as metabolites of benzo(j)fluoranthene and benzo(k)fluoranthene.

The metabolism of the environmental agents benzo(j)-fluoranthene and benzo(k)fluoranthene was investigated using supernatants from the livers of Aroclor 1254-pretreated rats, which are effective in activating benzo(j)fluoranthene and benzo(k)fluoranthene to metabolites mutagenic toward Salmonella typhimurium TA 100. Six bands of metabolites of benzo(j)fluoranthene were separated by high-pressure liquid chromatography, and each band was tested for mutagenicity toward S. typhimurium TA 100 with activation. The major mutagenic band contained two dihydrodiols, one of which was identified as 9,10-dihydro-9, 10-dihydroxybenzo(j)fluoranthene by comparison to a synthetic reference standard. 9,10-Dihydro-9,10-dihydroxybenzo(j)fluoranthene was mutagenic toward S. typhimurium TA 100 with activation, presumably as a result of conversion to the corresponding dihydrodiol-epoxide. The major dihydrodiol metabolite of benzo(k)fluoranthene was identified, by comparison to a synthetic standard, as 8,9-dihydro-8,9-dihydroxybenzo(k)fluoranthene. This dihydrodiol, which could also be converted to a dihydrodiol-epoxide, was mutagenic toward S. typhimurium TA 100 with activation. The results of this study indicate that metabolism to dihydrodiols is one pathway in the activation of benzo(j)fluoranthene and benzo(k)fluoranthene to ultimate mutagens for S. typhimurium TA 100.