title: Effects of acetylenic and olefinic pyrenes upon cytochrome P-450 dependent benzo[a]pyrene hydroxylase activity in liver microsomes.
abstract: 1-Ethynylpyrene, trans-, & cis-1-(2-bromovinyl)pyrene, methyl 1-pyrenyl acetylene, and phenyl 1-pyrenyl acetylene are substrates for cytochrome P-450 dependent monooxygenases and also inhibitors of cytochrome P-450 dependent benzo[a]pyrene hydroxylase activities in liver microsomes from 5,6-benzoflavone or phenobarbital pretreated rats. 1-Ethynylpyrene, trans-1-(2-bromovinyl)pyrene, and methyl 1-pyrenyl acetylene cause a mechanism based inhibition (suicide inhibition) of the benzo[a]pyrene hydroxylase activities in microsomes from 5,6-benzoflavone or phenobarbital pretreated rats, while cis-1-(2-bromovinyl)pyrene only causes suicide inhibition of the hydroxylse activities in the 5,6-benzoflavone induced microsomes and phenyl 1-pyrenyl acetylene does not cause a detectable suicide inhibition of these activities in either type of microsome. Incubation with NADPH and 1-ethynylpyrene, trans-, or cis-1-(2-bromovinyl)pyrene causes a loss of the P-450 content in the microsomes from 5,6-benzoflavone or phenobarbital pretreated rats, but incubations with methyl 1-pyrenyl acetylene or phenyl 1-pyrenyl acetylene did not cause a loss of the P-450 content of either microsomal preparation.
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000037:antagonists & inhibitors*; D001571:Benzoflavones / Q000494:pharmacology; D001579:Benzopyrene Hydroxylase / Q000037:antagonists & inhibitors*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D066298:In Vitro Techniques; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D010634:Phenobarbital / Q000494:pharmacology; D011721:Pyrenes / Q000494:pharmacology*; D051381:Rats; D013329:Structure-Activity Relationship; D019324:beta-Naphthoflavone
chemical_list: D001571:Benzoflavones; D011721:Pyrenes; D019324:beta-Naphthoflavone; D003577:Cytochrome P-450 Enzyme System; D001579:Benzopyrene Hydroxylase; D001189:Aryl Hydrocarbon Hydroxylases; D010634:Phenobarbital