Extraction And Separation Of The Polysaccharides, Saponin And Bioactive Protein In Astragalus Mongolicus

The extraction and separation of active components from Chinese medicinal herbs at high efficiency is one of the key research topics today. This study was carried out to broaden the use of Aslralagus mongolicus as well as to discover its new effective components. Major conclusions are as follow:1. Extraction and separation of Astragalus polysaccharide (APS)Dynamic analysis on the extraction process of Astragalus polysaccharide (APS) showed that double aqueous extraction at 60 min and 70 min was able to extract most of the APS from Astralagus mongolicus Bge. Effect of cellulase treatment on the APS extraction was also investigated in this study. Although content of the APS remained unchanged, yield of the APS increased for more than 20% after the cellulase treatment. Optimal condition for APS extraction was as follow: cellulose dosage 60U/g, incubation time 90 min and temperature 50 ℃. An ethanol precipitation concentration at 80% was found to be reasonable after studying the graded ethanol precipitation and stepwise ethanol precipitation. A series of hollow fiber ultrafiltration membrane was used to separate water-soluble extract systematically and membrane with cut-off of 50 kDa was found to be suitable for the separation of APS from other components. This report also describes the enzymatic removal of protein from the APS and this method was more superior than the Sevag's method. According to the immunologic test, the APS was an effective immunostimulating component. Its immunostimulating activity was strong and was better for live-wight growth.2. Extraction and separation of Astragalus sapnonin (AS)Various methods for the extraction and isolation of Astragalus sapnonin (AS), such as water-extraction, ethanol extraction and cellulase pretreatment, were carried out in this study. Results showed that ethanol extraction was slightly better than water-extration. Concentration of AS in ethanol precipitation supernatant was increased by enzyme pretreatment and showed an increment of more than 8%. Resin absorbing method significantly better than extraction refined by n-butyl alcohol. The rate and yield of AS were high when it was extracted by chromatography using AB-8 macroporous adsorption resin at 60% ethanol, resin column of 55 cm and elution concentration of 80%.3. Extraction, Purification and identification of bioactive proteinA novel bioactive protein (Astramonin 1) was isolated from the roots of Astragalus monghollcus using a combination of ammonium sulfate fractionation and ion exchange chromatographies. Astramonin 1 was a dimeric protein (61.1 kDa) and was composed of two identical subunits each with amolecular mass of 29.6 kDa. The protein was a glycoprotein with a neutral carbohydrate content of 19.6%. The purified protein hemagglutinated both rabbit and human erythrocytes, but with a preference for blood types O (native) and AB (trypsin-treated). Among the various carbohydrates tested, the protein was best inhibited by D-galactose and its derivatives with pronounced preference for lactose, Astramonin 1 may therefore be regarded as a galactose-specificic lectin. N-terminal amino acid sequence of Astramonin 1 was determined as ESGINLQGDATLANN. The optimal pH range for hemagglutinating activity was between pH 4.5 and pH 7.5, and the hemagglutinating activity was stable up to 65℃. Besides, it exerted antifungal activity against Botrytis cincerea, Fusarium oxysporum, Colletorichum sp. and Drechslera turcia but not against Rhizoctonia solani and Mycosphaerella arachidicola.