HPLC-MS/MS method to determine genipin in rat plasma after hydrolysis with sulfatase and its application to a pharmacokinetic study.

A sensitive high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the quantification of genipin in rat plasma after hydrolysis with sulfatase. Genipin could not be detected directly as it could be transformed into other forms such as conjugated-genipin immediately after administration. The conjugated genipin could be hydrolyzed by sulfatase to genipin. The conditions of hydrolysis were investigated. Genipin and the internal standard, peoniflorin (IS), were separated on a reversed-phase column by gradient elution and detected using an electrospray ion source on a 4000 QTrap triple-quadrupole mass spectrometer. The quantification was performed using multiple reaction monitoring with selected precursor-product ion pairs of the transitions m/z 225.0 → 122.7 and m/z 479.1 → 449.1 for genipin and peoniflorin. The assay was linear over the concentration range of 1.368-1368 ng/mL, with correlation coefficients of 0.9989. Intra- and inter-day precisions and accuracy were all within 15%. The lower limit of quantification was 1.368 ng/mL. The recoveries of genipin and peoniflorin were more than 53.3 and 51.2%. The highly sensitive method was successfully applied to estimated pharmacokinetic parameters of genipin following oral and intravenous administration to rats. The absolute bioavailability of genipin was 80.2% in rat, which is the first report.