title: Activation of monooxygenases in human liver by 7,8-benzoflavone.
abstract: Addition of 10(-4) M 7,8-benzoflavone to homogenates of human liver samples obtained by autopsy or surgical biopsy increased the rate of benzo[a]pyrene hydroxylation up to 11-fold. 7,8-Benzoflavone also increased the rates of hydroxylation of zoxazolamine and antipyrine at 10(-4) M but inhibited these reactions at 10(-6) M. The effects of 7,8-benzoflavone on the hydroxylation of benzo[a]pyrene and zoxazolamine in microsomes from human liver were similar to those in homogenates. Addition of 7,8-benzoflavone to homogenates of surgical biopsy samples of human liver had little or no effect on the rates of oxidative metabolism of 7-ethoxycoumarin, coumarin, and hexobarbital. Marked individuality for the activating and inhibiting effects of 7,8-benzoflavone was observed in different liver samples. This individuality may result both from the presence of multiple monooxygenases in varying amounts and proportions in the different liver samples and from a selective effect of 7,8-benzoflavone on certain of the monooxygenases.
mesh_terms: D000293:Adolescent; D000328:Adult; D000983:Antipyrine / Q000378:metabolism; D001344:Autopsy; D001580:Benzopyrenes / Q000378:metabolism; D001706:Biopsy; D003374:Coumarins / Q000378:metabolism; D003640:Dealkylation; D004789:Enzyme Activation; D005260:Female; D005419:Flavonoids / Q000494:pharmacology*; D006591:Hexobarbital / Q000378:metabolism; D006801:Humans; D006900:Hydroxylation; D066298:In Vitro Techniques; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology; D008875:Middle Aged; D010105:Oxygenases / Q000378:metabolism*; D015049:Zoxazolamine / Q000378:metabolism
chemical_list: D001580:Benzopyrenes; D003374:Coumarins; D005419:Flavonoids; D015049:Zoxazolamine; D006591:Hexobarbital; D010105:Oxygenases; D000983:Antipyrine