A rapid and simple RP-HPLC method for quantification of kirenol in rat plasma after oral administration and its application to pharmacokinetic study.

A rapid and simple reverse-phase high-performance liquid chromatography (RP-HPLC) was developed and validated for the quantification of kirenol in rat plasma after oral administration. Kirenol and darutoside (internal standard, IS) were extracted from rat plasma using Cleanert™ C(18) solid-phase extraction (SPE) cartridge. Analysis of the extraction was performed on a Thermo ODS-2 Hypersil C(18) reversed-phase column with a gradient eluent composed of acetonitrile and 0.1% phosphoric acid. The flow rate was 1.0 mL/min and the detection wavelength was set at 215 nm. The calibration curve was linear over the range of 9.756-133.333 µg/mL (r(2) = 0.9991) in rat plasma. The lower limits of detection and quantification were 2.857 and 9.756 µg/mL, respectively. The intra- and inter-day precisions (relative standard deviation, RSD) were between 2.24 and 4.46%, with accuracies ranging from 91.80 to 102.74%. The extraction recovery ranged from 98.16 to 107.62% with RSD less than 4.81%. Stability studies showed that kirenol was stable in preparation and analytical process. The present method was successfully applied to the pharmacokinetic study of kirenol in male Sprague-Dawley rats after oral administration at a dose of 50 mg/kg.