The Purification And Structure Modification Of Ginsenoside-RB1

Ginsenoside Rb1 is one of saponins from Panax Ginseng C.A.Meyer which is widely used as tradition medicine. This compound is a dammarane type triterpene, carrying a gentiobiose unit linked to C-20 and a sophorose unit linked to C-3, with a variety of biological activity. The sugar chain of Ginsenoside Rb1 is more easily modified than the aglycone with cycloalkane structure, and the sugar chains, playing an important role in structure-function relationship of ginsenosides. Compared to Ginsenoside Rb1, the structure of rare ginsenoside with high activity only lacks one or several glycosydls. The fatty acid ester compounds from enzyme hydrolysis of Ginseng saponins create a stronger anticancer activity. Accordingly, the synthesis of more active ginseng saponins (such as Rg3 and saponins derivatives) from Rb1 saponins with highest content but poor activity will be highly meaningful.The main results obtained from this work are as follows:1. We combines boiling method, macroporous resin, column chromatography and reverse phase column chromatography method to separate ginsenoside Rb1 from the ginseng root ,with the purity of the product up to 95%. The products were characterized by HPLC and 13C NMR spectra. The advantages of this method are: purity of ginsenoside Rb1 is high and the extraction process is relatively simple.2. In this paper, rare ginsenoside Rg3 was prepared using ginsenoside Rb1 as raw materials with high-temperature and high-pressure method. The following optimum reaction conditions were determined: substrate concentration, 5 mg/ml; solvent, the mass fraction of AcOH 2.5%; pressure, 0.13 MPa; reaction time, 1 h. Using this method, the Rg3 purity could achieve 90%.3. The acetylation of Ginsenoside Rb1 was carried out using the classical method–pyridine and acetic anhydride. The following optimum reaction conditions were determined: the acetylation reagent, 2 equ; reaction time, 2 h; reaction temperature, the room temperature. The product Rb1-Ac-1 and Rb1-Ac-2 were purified by silica gel column chromatography and then characterized by IR and 13C-NMR spectra. This study expanded the structural diversity of natural saponins, which is of great significance for improving the biological activity of saponins. 4. The Sulfation of Ginsenoside Rb1 was performed using chlorosulfonic acid as sulfation reagent and pyridine as catalyst and solvent. The following optimum reaction conditions were determined: the sulfation reagent, 10 equ; reaction time, 1 h; reaction temperature, the room temperature. The product Rb1-S was purified by silica gel column chromatography, then characterized by IR and 13C-NMR spectra. This study will explore new fields for activity research of ginseng saponins on anticancer, immune regulation and hypoglycemic et.al, and provide candidate compounds with a variety of structure types for drug screening of such kind.