Analytical and experimental validations of thin-layer chromatographic determination of Rb1 and Rg1 of ginsenosides

Traditionally, the ratio Rg1/Rb1 is linked to the ethnopharmacology properties of ginseng preparations because Rb1 acts as weak CNS (central nerve system) depressant while Rg1 stimulates the CNS. Such a pharmacokinetics difference is also linked to the properties of ginsengs originated at different places. A simple, sensitive, selective, precise, and stability-indicating thin layer chromatographic method was developed and validated. The purified ginsenosides, Rb1 and Rg1, was used as a standard. Prior to TLC application, all the standards and the extract of 1 mmg were dissolved in 100% methanol. The stationary phase of TLC plates used for separation and detection of ginsenosides was silica gel 60 F254 pre-coated aluminum sheet (0.2 mm, 20 x 20 cm). The mobile phase consisted of BuOH, Ethyl acetate, water (5:1:4). The plates were pre-washed by methanol and activated at 60oC for 5 min. Each sample and standard, 1 ?l, was spotted in the form of bands of width 10 mm with microliter syringe on the plates. The development was carried out in the glass chamber of 20 cm x 10 cm saturated for 30 min at room temperature. Densitometry scanning was performed using LJ Color 2840. The intensity of density of spots was evaluated using Scion Image Program. Compact spots for and were found at Rf values of 0.154 ± 0.04 and 0.581 ± 0.014, respectively. The linear regression analysis for calibration plots good linear relationship with r=0.998 (Rb1) and r=0.994 (Rg1) in the working concentration range of 100 to 1000 ng. The method was validated for precision, accuracy, recovery, and limit detection, and limit of quantification.