The influence of various enzyme inducers on the microsomal metabolism of 7,8-benzoflavone.

Comparative in vitro metabolic experiments with 7,8-benzoflavone using microsomes prepared from the livers of control Sprague-Dawley rats or from rats of the same strain treated with phenobarbitone, 3-methylcholanthrene, or Aroclor 1254 (known inducers of hepatic cytochrome P450 mixed function oxidases) disclose variable amounts of the three metabolites previously reported, namely the 5,6-epoxide, 9,10-dihydro-9,10-diol, and the 5 (or 6)-phenol. Microsomes from phenobarbitone-treated rats gave in addition a small amount of the 5,6-dihydro-5,6-diol, identified by mass spectrometry and u.v. spectroscopy. The apparent discrepancy between our previous results (1) and those of Nesnow and Bergman (2) is therefore partly resolved, although the absence of the 9,10-diol from their products remains unexplained, but may have resulted from their use of rats of a different strain.