Oxidation of dihydroagnosterol by human P450 51A1. The incubation included 0.1 μM P450 51A1 and 10 μM dihydroagnosterol and ran for 10 min at 37 °C in the absence and presence of NADPH. The products were extracted and analyzed by UPLC-UV and UPLC-MS. A, UPLC chromatogram (UV, 192 and 245 nm). B, mass spectrum [M+H-H2O]+, calculated for C29H45, 393.3516; found, 393.3493 (−5.9 ppm) and assigned structure. C, UV spectrum (from tR 7.3 min peak of A). UPLC, ultra-performance liquid chromatography.