Determination of ginsenoside Rh3 in rat plasma by LC-MS/MS and its application to a pharmacokinetic study.

Ginsenoside Rh3 (GRh3) is a bacterial metabolite of ginsenoside Rg5, which is the main component of hot-processed ginseng. A simple, efficient and sensitive method was developed and validated for the determination of GRh3 in rat plasma by LC-MS/MS. After protein precipitation with methanol/acetonitrile (1:1, V/V) including Propranolol (internal standard), the target analytes were separated on an Agilent XDB C18 column, methanol containing 0.1% formic acid and water containing 0.1% formic acid were used as mobile phases for gradient elution. Mass spectrometry was detected by electrospray ion source (ESI) positive ion mode and multiple reaction monitoring mode (MRM) , monitoring the transitions m/z 622.5→425.5 for and m/z 260.1→116.1 for GRh3 and IS respectively. The concentration range of GRh3 was 20-20000 ng/mL and the correlation coefficient (r2 ) was greater than 0.99. The accuracy error (RE%) and relative standard deviation (RSD%) were below 15%. The extraction recovery and matrix effect were 74.2 to 78.7% and 96.9 to 108.4%, respectively. Under different conditions, the GRh3 was stable in the range of 1.8 ~ 8.7%. This method has been successfully applied to study the pharmacokinetics of GRh3 with oral dose of 10.0 mg/kg and intravenous dose of 2.0 mg/kg in rats, respectively. The absolute bioavailability of GRh3 was 37.6%.