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Activation of monooxygenases in human liver by 7,8‐benzoflavone
Author(s) -
Kapitulnik J.,
Poppers P. J.,
Buening M. K.,
Fortner J. G.,
Conney A. H.
Publication year - 1977
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1002/cpt1977224475
Subject(s) - monooxygenase , hydroxylation , chemistry , hexobarbital , microsome , human liver , metabolism , cytochrome , pyrene , biochemistry , liver biopsy , endocrinology , medicine , cytochrome p450 , biopsy , enzyme , biology , organic chemistry
Addition of 10‐ 4 M 7,8‐benzojlavone to homogenates of human liver samples obtained by autopsy or surgical biopsy increased the rate of benzo [a] pyrene hydroxylation up to II‐fold. 7,8‐Benzojlavone 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‐benzojlavone on the hydroxylation of benzo[a]pyrene and zoxazolamine in microsomes from human liver were similar to those in homogenates. Addition of 7,8‐benzojlavone 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‐benzojlavone 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‐benzojlavone on certain of the monooxygenases.