FIGURE 8.

CYP126A1-dependent oxidation of compound 4. A, LC extracted ion chromatogram of CYP126A1 extracts following enzymatic incubations with compound 4. Major peaks with retention times (rt) at 2.791 and 3.231 min are observed, with minor species at 2.916, 3.074, and 3.912 min. The peak at 2.791 min (shaded in gray) corresponds to the (+16) hydroxylation of compound 4. B, mass spectrum following LC separation of the extracted major product at 3.231 min, with m/z 442.1528 (M + H) diagnostic of the parent substrate ion of compound 4 ((C₂₃H₂₄ClN₃O₄) + H)⁺ and a smaller species with m/z 464.1348 for the compound 4 sodium ion adduct. C, mass spectrum of the extracted 2.791-min peak showing the (+16) hydroxylation of compound 4 with m/z 458.1477 ((C₂₃H₂₄ClN₃O₅) + H). Inset, amplification of the peak m/z 458.1477, showing the ionization pattern for the hydroxylated form of compound 4.