the metabolism of 1hydroxy and 2hydroxy3methylcholanthrene by liver microsomes effect of enzyme inducing agents the metabolism of both 1hydroxy3methylcholanthrene 1oh3mc and 2hydroxy3methylcholanthrene 2oh3mc by rat liver microsomes was investigated metabolites were separated by high pressure liquid chromatography hplc both compounds were shown to be substrates for further metabolism metabolism of 1oh3mc gave rise to at least 13 products while 2oh3mc showed the formation of at least 10 metabolites at least 3 products of the 1oh3mc metabolism are diol derivatives of the substrate using 2oh3mc as substrate generated one major diol derivative that represented between 20 and 50 of total metabolite formation pretreatment of animals with known microsomal enzyme inducing agents did not result in the expected induction patterns in some instances the microsomes from induced animals were less efficient at metabolizing substrate than those from control the discovery of a major peak from 2oh3mc metabolism is of extreme importance considering the potency of the parent hydroxy compound in tumor initiation studies