Measurement of In Vitro Cytochrome P450 2B6 Activity

Abstract

Cytochrome P450 2B6 (CYP2B6) is responsible for the metabolism of a number of therapeutically relevant drugs and environmental chemicals. While not as frequently involved in xenobiotic metabolism as other more commonly studied P450 enzymes such as CYP3A, CYP2D6, or CYP2C9, its importance is becoming increasingly realized. Bupropion hydroxylase activity is an excellent indicator of in vitro CYP2B6 activity, and the metabolite formed is easily measured by HPLC/MS/MS. This assay allows the use of very low concentrations of human liver microsomes or recombinant enzyme, and it represents a selective, sensitive approach to assessing in vitro CYP2B6 activity, with minimal sample preparation.

Characterization of CYP2B6 in a CYP2B6-Humanized Mouse Model: Inducibility in the Liver by Phenobarbital and Dexamethasone and Role in Nicotine Metabolism In Vivo

“…Bupropion hydroxylase activity was determined essentially as described (Walsky and Obach, 2009). Incubation mixtures consisted of 0.2 mg of liver microsomal protein, 50 mM bupropion chloride, 50 mM potassium phosphate buffer (pH 7.4), 5 mM magnesium chloride, and 1 mM NADPH, in a total volume of 0.2 ml.…”