Figure 1.

CYP2D6-mediated hydroxylation of primaquine. A. Shown is the MS^E fragmentation spectrum for primaquine. The (M + 1) charge state of primaquine is highlighted in blue. The major fragment ions of primaquine produced upon MS^E fragmentation are also shown along with their corresponding m/z values and structures. B. MS^E fragmentation of hydroxylated primaquine. Fragment ions utilized for localization of the hydroxylation to the quinoline core are indicated in red. It should be noted that MS^E fragmentation localizes this transformation to the quinoline core, and that the assignment shown is tentative.