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2137940 
Technical Report 
The enhancement of biphenyl 2-hydroxylation by carcinogens in vitro 
Mcpherson, FJ; Bridges, JW; Parke, DV 
1975 
PESTAB/76/0705 
Soc 
4 
618-619; 1975 
PESTAB. Hepatic microsomal preparations from adult male Syrian hamsters or adult male Wistar rats were added to a regenerating system containing glucose 6-phosphate, glycose 6-phosphate dehydrogenase, and one of a variety of carcinogens or noncarcinogens. After 5 min incubation, biphenyl was added and the incubation continued for 5 more min. A number of carcinogens, including butter yellow, dimethylnitrosamine, aflatoxin B1, 3-methylcholanthrene, 2-acetamidofluorene, and safrole produced a significant elevation in biphenyl 2-hydroxylation but had no effect on or slightly inhibited biphenyl 4-hydroxylation. Noncarcinogenic compounds such as phenobarbitone, nikethamide, aniline, and 1,2,3,4-dibenzpyrene did not increase biphenyl 2-hydroxylation. Other microsomal drug-metabolizing enzymes (p-nitroanisole demethylase, nitroreductase, aniline hydroxylase, and cytochrome P-450 reductase) were unaffected by the presence of carcinogens. The results suggest that enhanced biphenyl 4-hydroxylation, but not enhanced biphenyl 2-hydroxylation, requires de novo microsomal enzyme synthesis.