Simultaneous enantiomer determination of 20 (R)- and 20 (S)-ginsenoside-Rg2 in rat plasma after intravenous administration using HPLC method

20 (R,S)-Ginsenoside-Rg(2,) an anti-shock agent, is prescribed as a racemate. To asnaslyze simultaneously the enantiomers of 20 (R)-ginsenoside-Rg(2) and 20 (S)-ginsenoside-Rg(2) in plasma, a simple and reproducible high-performance liquid chromatographic (HPLC) method has been developed. The enantiomeric separation and determination were successefully achieved using a Diamonsil (TM) ODS C-18 reversed-phase column (5 mu m, 250 mm x 4.6 mm) with an RP18 (5 mu m) guard column and a mobile phase of MeOH-aq. 4% H3PO4 (65:35, v/v, pH 5.1) with UV detection at 203 nm. Both enantiometers, 20 (R)-ginsenoside-Rg(2) and 20 (S)-ginsenoside-Rg(2), were well separated at 14.5 min and 13.6 min, respectively. The linear ranges of the standard curves were 2.0-250 mu g/ml. The intra- and inter-day precision (R.S.D.) were <= 1.59% and <= 0.54% and the mean extraction recoveries were 95.8% and 96.5% for 20 (R)-ginsenoside-Rg(2) and 20 (S)-ginsenoside-Rg(2) in rat plasma, respectively. The limits of detection and quantification were 2.0 mu g/ml and 7.8 mu g/ml (S/N = 3:1) for 20 (R)-ginsenoside-Rg(2), and 20 mu g/ml and 3.9 mu g/ml (S/N = 3:1) for 20 (S)-ginsenoside Rg(2), respectively. This validated method was applicable to pharmacokinetic studies in rat plasma after intravenous administration of 20 (R,S)-ginsenoside-Rg(2). A pharmacokinetic study in rat plasma indicated that the enantiomers were rapidly absorbed and eliminated. These assays results are necessary for he evaluation of the metabolism of ginsenoside-Rg(2) in vivo. (c) 2006 Elsevier B.V. All rights reserved.