Study On Extration, Purification Of Polysaccharide From Astrgalus Membranaceus And Its Anti-oxidation Activity In Vitro

Objective:Astrgalus membranaceus has a long history of medicinal use in traditional Chinese medicine. Astrgalus membranaceus possesses various pharmacological action, including immune regulation, cardiac bucking, hypoglycemic, anti-stress, anti-tumor, anti-virus, anti-radiation, anti-oxidation and so on. The relative reports indicated that Astrgalus membranaceus consists of various pharmacological fractions. Astrgalus membranaceus polysaccharide has become one of the most important fractions which has been focused on. Researchers have found that Astrgalus membranaceus polysaccharide has an excellent capacity on enhancing activity of GSH-PX and on antioxidant and anti-aging in mice. It suggests that Astrgalus membranaceus polysaccharide may possess various antioxidant activities, so further studies are required for this point. In this study, different polysaccharide fractions from Astrgalus membranaceus were extracted, and their antioxidant action in vitro and mechanism were analysis.Methods:Crude Astrgalus membranaceus polysaccharide (cAMPS) was isolated from Astrgalus membranaceus by hot water and ethanol precipitation. By protease enzymatic hydrolysis of Streptomycetaceae, Sevag method, DEAE-cellulose ion-exchange column chromatography and Sepharose-CL-6B gel column chromatography purification, the purified polysaccharide fractions, including AMPSA-a, AMPSA-b, AMPSA-c and AMPSB-d were got. To study anti-oxidation capacities of different fractions in vitro, DPPH free radical, pyrogallol autoxidation method and Fenton reaction were selected.Results:The result of high performance liquid chromatography (HPLC) indicated that Astrgalus membranaceus polysaccharide fractions are homogeneous. molecular weight 134.9,69.4,61.5and 46.1kDa。The Gas chromatography(GC) results indicated that mannose(Man), galactose(Gal) and glucose (Glc) are the main monosaccharide compositions in all the fractions. The study of anti-oxidation indicated that different fractions could significantly scavenge DPPH free radical, O2-. free radical and.OH free radical in a dose-dependent manner. Several concentrations were selected to detect the capacities of different fractions on scavenging DPPH free radical, O2-. free radical and.OH free radical. The results indicated that different fractions exhibited significant anti-oxidation effects at a concentration of 8 mg/ml. The capacities of different fractions AMPSB-d, AMPSA-b, AMPSA-a and AMPSA-c on scavenging DPPH free radical were 87.2%,65.3%,58.6% and 55.4% at a concentration of 8 mg/ml, respectively. The capacities of different fractions on scavenging O2-. free radical were 32.4%,41.2%,42.3% and 45.6% at a concentration of 8 mg/ml, respectively. The capacities of different fractions on scavenging.OH free radical were 32.4%,38.6%,35.1% and 39.6% at a concentration of 8 mg/ml, respectively and all fracpions had near capacities on this effect.Conclusion:1. Four polysaccharide fractions of AMPSA-a, AMPSA-b, AMPSA-c and AMPSB-d, have been isolated from Astrgalus membranaceus. 2. All the isolated polysaccharide fractions have exhibited significant anti-oxidation effects, especially with the strongest effect to scavenge DPPH free radical.