An LC-MS/MS method for quantification of demethylzeylasteral, a novel immunosuppressive agent in rat plasma and the application to a pharmacokinetic study.

In this study, a sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of demethylzeylasteral in rat plasma. Electrospray ionization was operated in the negative ion mode while demethylzeylasteral and oleanolic acid (internal standard) were measured by selected reaction monitoring (demethylzeylasteral: m/z 479.2 → 436.0; oleanolic acid: m/z 454.9 → 407.2). This LC-MS/MS method had good selectivity, sensitivity, accuracy and precision. The pharmacokinetic profiles of demethylzeylasteral were subsequently examined in Wistar rats after oral or intravenous administration.