A rapid and sensitive HPLC–MS/MS analysis and preliminary pharmacokinetic characterization of sibiricaxanthone F in rats

A simple, rapid and sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated for quantifying sibiricaxanthone F (SF) in rat plasma following oral and intravenous dosings. After addition of the internal standard (IS) kaempferol and the antioxidant, 20% ascorbic acid, plasma samples were precipitated with acetonitrile and separated on an Aglient Zorbax XDB-C18 column (50 mm × 4.6 mm I.D., 2.1 μm) with gradient acetonitrile and water (both containing 0.01% formic acid) as the mobile phase. The detection was performed on a Sciex API 4000 LC–MS/MS with electrospray ionization (ESI) inlet in the negative multiple reaction monitoring (MRM) mode. Good linearity was achieved over the concentration range of 0.5–500.0 ng/mL (r > 0.996). Intra- and inter-day precisions were less than 7.60%, and accuracy ranged from 97.18% to 99.84%. The lower limit of quantification for SF was 0.5 ng/mL, and analytes were stable under various conditions (during freeze-thaw, at room temperature and under deep-freeze conditions). This validated method was successfully applied to the preliminary pharmacokinetic study of SF in rats for the first time, and the absolute bioavailability of SF was found to be only 0.22 ± 0.15%.