Metabolism of benzo(a)pyrene in bovine lens epithelium

Bovine lens epithelium contains an enzyme system that metabolizes the carcinogen benzo(a)-pyrene. The major ethylacetate-soluble metabolites are 7,8-dihydro-7,8-dihydroxybenzo(a)-pyrene, 9,10-dihydro-9,10-dihydroxybenzo(a)pyrene and 3-hydroxybenzo(a)pyrene. Addition of 1,1,1-trichloropropene-2,3-oxide (TCPO), an inhibitor of expoxide hydratase, prevents the formation of the dihydrodiols. The overall metabolism can be inhibited by the addition of α-naphthoflavone. The metabolism of benzo(a)pyrene in cultured lens epithelial cells has also been studied. It is found that the activity of aryl hydrocarbon hydroxylase (AHH) is strongly decrease in culture. The decline in AHH activity can be reduced by the addition of an unphysiological concentration of nicotinamide.