Metabolites of phenanthridine formed by rat liver homogenate.

The ethyl acetate-extractable metabolites of phenanthridine as formed in vitro with Aroclor-induced rat liver homogenate were isolated and structurally identified. The relative amounts of these metabolites were determined using [6-14C]phenanthridine. The major metabolites of phenanthridine formed under these incubation conditions were identified as phenanthridine-N-oxide, 1,2-dihydroxy-1,2-dihydrophenanthridine, and 9,10-dihydroxy-9,10-dihydrophenanthridine. Phenanthridone and 2-hydroxyphenanthridine were identified as minor metabolites. These data were obtained using an identical incubation mixture as employed in mutagenicity assays. It is suggested that metabolites in addition to phenanthridone are likely to contribute to mutagenicity of phenanthridine observed in assays performed with metabolic activation.