title: Potent induction of rat liver microsomal, drug-metabolizing enzymes by 2,3,3',4,4',5-hexabromobiphenyl, a component of fireMaster.
abstract: The multistep synthesis and purification of 2,3,3',4,4',5-hexabromobiphenyl (HBBp) is described. Capillary gas chromatography revealed that HBBp comprises 0.05% of the industrial polybrominated biphenyl (PBB) mixture, fireMaster BP-6 (lot 7062). When administered to immature male Wistar rats, HBBp caused a dose-dependent increase in (a) the activity of benzo[a]pyrene (B[a]P) hydroxylase (AHH) and 4-chlorobiphenyl (4-CBP) hydroxylase and (b) the concentration of cytochrome P-450. Sodium dodecyl sulfate (SDS)-gel electrophoresis indicated that these increases in cytochrome P-450 and cytochrome P-450-dependent monooxygenase activities were accompanied by a dose-dependent intensification of a protein of relative molecular weight (Mr) 55 000 which comigrated with the major 3-methylcholanthrene(MC)-inducible form of cytochrome P-450 (i.e., cytochrome P-448). Like MC, but in contrast to phenobarbitone (PB), HBBp competitively displaced 2,3,7,8-[3H]tetrachlorodibenzo-p-dioxin ([3H]-TCDD) from the cytosolic protein thought to be the receptor for cytochrome P-448 induction. The results indicate that HBBp is a potent inducer of cytochrome P-448 and as such is the third MC-type inducer identified in fireMaster BP-6.
mesh_terms: D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases / Q000096:biosynthesis; D001713:Biphenyl Compounds / Q000494:pharmacology*; D019388:Cytochrome P-450 CYP1A2; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D003580:Cytochromes / Q000378:metabolism; D004790:Enzyme Induction / Q000187:drug effects*; D005411:Flame Retardants / Q000138:chemical synthesis / Q000494:pharmacology*; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology; D008862:Microsomes, Liver / Q000201:enzymology*; D010634:Phenobarbital / Q000494:pharmacology; D011075:Polybrominated Biphenyls / Q000138:chemical synthesis / Q000494:pharmacology*; D051381:Rats; D018336:Receptors, Aryl Hydrocarbon; D011955:Receptors, Drug / Q000378:metabolism
chemical_list: D001713:Biphenyl Compounds; D003580:Cytochromes; D005411:Flame Retardants; D011075:Polybrominated Biphenyls; D018336:Receptors, Aryl Hydrocarbon; D011955:Receptors, Drug; D008748:Methylcholanthrene; C015885:Firemaster BP-6; C029187:2,3,3',4,4'5,6-heptabromobiphenyl; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; C017170:Cyp1a2 protein, rat; D019388:Cytochrome P-450 CYP1A2; C029186:2,3,3',4,4',5-hexabromobiphenyl; D010634:Phenobarbital