A rapid and sensitive liquid chromatography-tandem mass spectrometric method for determination of actinoside E in rat plasma and application to a pharmacokinetic study

A highly sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for the determination of actinoside E in rat plasma. The analytes were extracted by ethyl acetate and an analogue of actinoside F was used as the internal standard. The mobile phase consisted of methanol-water (50 : 50, V/V) containing 0.1% formic acid was delivered at a flow rate of 0.3 mL.min(-1) to a Zorbax SB-C-18 column (100 nun x 2.1 mm, 3.5 mu m). The detection was performed by electrospray ionization mass spectrometry in the negative multiple reaction monitoring mode with a chromatograph run time of 3.0 mm. Calibration curves of actinoside E were linear in the range of 0.5-2 500 ng.mL(-1). In this range, intra- and inter-day precision ranged from 1.7% to 7.5% and 2.0% to 8.9%, respectively. The accuracy ranged from 95.7% to 108.6%, and extraction recovery from 83.2% to 85.5%. This method was successfully applied to a pharmacokinetic study of actinoside E in rats after intravenous (5 mg.kg(-1)) and oral (100 mg.kg(-1)) administration, and the results showed that actinoside E was poorly absorbed with an absolute bioavailability being approximately 0.27%.