Determination of ginsenoside Rc in rat plasma by LC-MS/MS and its application to a pharmacokinetic study

Ginsenoside Rc (GRc) is a potential pharmacologically active ingredient isolated from ginseng (Panax ginseng C.A. Meyer, Araliaceae). A simple, rapid and sensitive method for determination of GRc in rat plasma was developed based on liquid chromatography-tandem mass spectrometry (LC-MS/MS). The analyte and internal standard (IS), ginsenoside Rb(1) (GRb(1)), were extracted from plasma with n-butanol and chromatographied on a C(18) column eluted with a mobile phase of methanol and water containing 0.1% formic acid. The detection was performed by positive ion electrospray ionization in selective reaction monitoring mode (SRM), monitoring the transitions m/z 1101.6→789.3 and m/z 1131.7→364.7 for GRc and IS, respectively. The assay was linear over the concentration range of 5-5000 ng/mL with a limit of quantitation (LOQ) of 5 ng/mL. The accuracy was between 86.7% and 114.9%, and the precision was less than 9.7%. This method was successfully applied to investigate the pharmacokinetic study of GRc in rats after intravenous (2mg/kg) and oral (20mg/kg) administration, and the result showed that the ginsenoside was poorly absorbed with an absolute bioavailability being approximately 0.17%.