Study On Preparation Of Ginsenoside-Rg3

Ginseng, the root of Panax ginseng C. A. Meyer of the Araliaxeae family, is one of most well-known Chinese traditional medicines. The ginsenosides are the main active components of ginseng with various benefit pharmacological actions, and they were used extensively in industries of medicine, domestic chemistry, food and animal feed. Recently, studies on antitumor action of several rare ginsenosides, especially ginsenoside-Rg3 and -Rh2, were attracting. In this paper, the structure-activity relationship of ginsenosides on antitumor action and preparation of ginsenoside-Rg3 and ginsenoside-Rh2 were reviewed.Now, some preparation methods of ginsenoside-Rg3 have disadvantages such as long times and low yields. Microwaves can speed-up chemical reaction. But intensification of hydrolysis by microwave in preparation ginsenoside-Rg3 has not been reported.1) The high performance thin layer chromatographic (HPTLC) and thin layer chromatographic method to qualitatively analyze ginsenoside-Rg3 were developed. The optimal conditions of thin layer chromatographic were as follow: silica gel G as stationary phase, n-butanol -ethyl acetate-water(4:1:5, v/v/v) as the mobile phase, coloration by spraying sulfuric acid. Under these conditions, a good separation was obtained, and the Rf value of ginsenoside-Rg3 was 0.53.2) A method of the reverse phase high performance liquid chromatographic (HPLC) determination of ginsenoside-Rg3 was developed. The optimal HPLC conditions were as follow: Apollo C18 column as the stationary phase, methanol -water (88:12, v/v) as the mobile phase, 1mL/min of flow rate, 30 of column temperature, UV detector(203nm). Under these conditions, a baseline separation of ginsenoside-Rg3 was obtained, and the retention time of ginsenoside-Rg3 is 10.6 minutes. The linear range is 0.4 g to 4 g. The calibration equation is M =3.86778 10-7 A+0.0214085. The related coefficient is 0.999. The RSD is 1.36%. The average recovery is 98.3 %.The extraction of crude ginsenosides from ginseng and separation of the ginsenosides of protopanaxdiol group from the crude ginsenosides were studied. The extraction of total ginsenosides was performed by Refluxing ethanol. Then, the extracts were purified by AB-8 resin. Thus the ginsenosides were obtained. Last, separation of the ginsenosides of protopanaxdiol group from the ginsenosides was carried out by liquid-liquid extraction. The yield of the ginsenosides of protopanaxdiol group was 35.5 %.Preparation of ginsenoside-Rg3 from the ginsenosides of protopanaxdiol group by hydrolysis with microwaves method was first carried out. The optimal conditions were as follow: P4(225W, v =2450 50 MHz), 10minutes of reaction time , 0.5mol.L-1 of HC1. The mechanics of hydrolysis with microwaves were deeply discussed. A new idea of the author was put forwards. By combination of preparative thin layer chromatography (PTLC) and preparative high performance liquid chromatography (PHPLC), a high-purity ginsenoside-Rg3 sample was obtained. The product was identified as ginsenoside-Rg3 by mass spectrum and nuclear magnetic resonance.