Ultra-high-performance liquid chromatography-tandem mass spectrometry for pharmacokinetics of bakuchiol in rats.

Psoralea Corylifolia L. is a traditional Chinese medicine with many beneficial effects in medical therapies. Bakuchiol was the main active ingredient of Psoralea Corylifolia L., used for the treatment of various diseases and also as a natural food additive. A specific and reliable ultra-high performance liquid chromatography-tandem mass spectrometry has been developed and fully validated for the quantification of bakuchiol in rat plasma. Chromatographic separation of bakuchiol and an internal standard, daidzein, was achieved on a Hypersil Gold C18 column with gradient elution that consisted of methanol and water at a flow rate of 0.2 mL/min. The compounds were detected at negative ionization mode using mass transition m/z 255.2 → 172.0 and 252.9 → 132.0 for bakuchiol and daidzein, respectively. Good linearity was obtained over the range of 2-1000 ng/mL and the lower limit of quantification was 2 ng/mL. The intra- and inter-day accuracies ranged from 91.1 to 105.7% and precisions (relative standard deviations) were within 9.3%. Bakuchiol was found to be stable under three freeze-thaw cycles, short-term temperature, post-preparative and long-term temperature conditions. The method was applied to a pharmacokinetic study of bakuchiol intravenously administered to rats at a dose of 5 mg/kg.