The in vitro metabolism of 2,2',4,4',5,5'-hexabromobiphenyl

Radiolabelled 2,2',4,4',5,5'-hexabromobiphenyl was metabolized in vitro by rat liver microsomal enzymes to give more polar ether soluble lipophilic metabolites, trichloroacetic acid soluble conjugates and a macromolecular adduct fraction. The rates of formation of the three metabolic fractions were significantly enhanced using Firemaster BP-6 and 2,2',4,4',5,5'-hexabromobiphenyl induced microsomal enzymes. Comparative metabolic studies with the 4-brombiphenyl substrate showed that the lower brominated biphenyl substrate was more readily metabolized and the rate of metabolism was enhanced only with the Firemaster BP-6 induced microsomal enzymes and not the 2,2', 4,4',5,5'-hexabromobiphenyl induced enzyme system.