Dibenz[a,j]acridine metabolism: identification of in vitro products formed by liver microsomes from 3-methylcholanthrene-pretreated rats.

The metabolism of the carcinogenic pentacyclic azaaromatic compound, dibenz[a,j]acridine, has been examined in liver microsomal incubations using preparations from 3-methylcholanthrene-pretreated Wistar rats. Using authentic synthetic standards, u.v. spectroscopy and mass spectrometry, the following were proved to be metabolites: trans-5,6-dihydro-5,6-dihydroxydibenz[a,j]acridine, trans-3,4-dihydro-3,4-dihydroxydibenz[a,j]acridine, dibenz[a,j]acridine-5,6-oxide, 3-hydroxydibenz[a,j]acridine and 4-hydroxydibenz[a,j]acridine. The 3,4-dihydrodiol appeared to be the major metabolite. The secondary metabolites were also examined and evidence is presented for the additional formation of dibenz[a,j]acridine-5,6,8,9-dioxide, tetrols, diol epoxides and phenolic dihydrodiols.