Study On Screening Of Polysaccharides As α-glucosidase Inhibitors And Its Hypoglycemic Activity

Diabetes becomes the major diseases of serious harm to human life. The a-glucosidase inhibitor is the drug as the clinical treatment of diabetes application rate more than 20%. In recent years, a-glucosidase inhibitor extracting from natural product has received concern. Polysaccharide as an important part of the natural product has a variety of biological features. The researches of polysaccharide as a-glucosidase inhibitor have crucial significance.The crude polysaccharides were extracted by boiled water and precipitated by ethyl alcohol from Astragalus, mushroom, yacon and swan-mussel and named as APS-1, MPS-I,YPS-1 and SMPS-1. The sugar contents of APS-1,MPS-1,YPS-1 and SMPS-1 respectively were 53.4%,31.3%,56.3% and 42.14% by phenol-sulfuric acid method. The protein was removed by Sevage. The sugar contents of APS-II,MPS-II,YPS-II and SMPS-II separately were 67.1%,36.5%,74.1%and 81.5%. APS-Ⅲ,MPS-Ⅲ,YPS-Ⅲ and SMPS-III were obtained by bleaching and purifing separately. The total sugar contents of APS-III,MPS-III,YPS-Ⅲ and SMPS-Ⅲ were 99%,41.1%,79.8% and 96.47%, separately.The system to screen the a-glucosidase inhibitors in vitro was established by screening the optimum substrate, the substrate concentration and the optimum enzyme activity unit of yeast a-glucosidase and mice a-glucosidase. The conditions of the system in vitro which screening of a-glucosidase inhibitors were enzyme solution 10μL, the concentration of yeast a-glucosidase and mice a-glucosidase both 0.2U·mL-1, the solution of maltose 5μL, the concentration of maltose 30mmol·L-1 and 40mmol·L-1, the sample or the positive control 5μL. The product of reaction was detected by the glucose oxidase method.The polysaccharides of astragalus, mushroom, yacon and swan-mussel as a-glucosidase inhibitors were screened by the system, the acarbose used as a positive control. The inhibition rate of Astragalus, mushroom, yacon and swan-mussel on yeast a-glucosidase separately were 40.1%,66.2%,21.9% and 17%, and on mice a-glucosidase respectively were 38.7%、45.1%、26.9%　andl9.1%　when the relatively sugar content were 0.4mg·mL-1. The polysaccharides of astragalus and mushroom both have a strong inhibtion of the both a-glucosidase. The polysaccharide of astragalus has the concentration dose dependence by the trial of the effect of sugar concentration on a-glucosidase. The effect of different purity polysaccharides on a-glucosidases provides the purified polysaccharides have the more strength inhibition on a-glucosidases than the crud polysaccharides. The hypoglycemic activities of four polysaccharides were investigated by animal experiments. The results showed that:it has obviously hypoglycemia that Astragalus polysaccharides role in hyperglycemia mice (p<0.01), and has the concentration dose dependence. MPS-Ⅱ L, MPS-ⅡM, YPS-ⅡL and YPS-ⅡM had effect on decreasing FBG (p<0.05). Four polysaccharides body hypoglycemia effect are consistent with the in vitro experimental.