In Vitro Metabolism. Human liver microsomes (1 mg/mL protein final concentration) or mouse liver microsomes (1 mg/mL protein final concentration) were incubated in 100mM potassium phosphate buffer pH 7.5 containing 5 mM magnesium chloride and 1 mM NADPH. Reaction mixtures were preincubated at 37°C for 2 minutes prior to the addition of 1, 2, or 3 (10 µM) to start the reaction. The reactions were stopped after 60-minute incubation at 37°C with the addition of a double volume of ACN. Following centrifugation, an aliquot of the supernatant was analyzed by LC-MS/MS. Control reactions without cofactor were also run.