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

Comparative in vitro metabolic experiments with 7,8-benzoflavoneusing microsomes prepared from the livers of control Sprague-Dawleyrats or from rats of the same strain treated with phenobarbitone,3-methylcholanthrene, or Aroclor 1254 (known inducers of hepaticcytochrome P450 mixed function oxidases) disclosed variableamounts of the three metabolites previously reported, namelythe 5,6-epoxide, 9,0-dihydro-9, 10-diol, and the 5 (or 6)-phenol.Microsomes from phenobarbitone-treated rats gave in additiona small amount of the 5,6-dihydro-5,6-diol, identified by massspectrometry and u.v. spectroscopy. The apparent discrepancybetween our previous results (1) and those of Nesnow and Bergman(2) is therefore partly resolved, although the absence of the9,10-diol from their products remains unexplained, but may haveresulted from their use of rats of a different strain.