| a-Glucosidase inhibitors can retard the absorption of glucose to improve postprandial hyperglycemia effectively. They are applied for the treatment of diabetes extensively. Edible fungus is a large category fungus of high food and medicinal value. The fungal metabolites have a variety of structure types and physical activity, so it is to be found an important new source of natural medicine.Firstly, the inhibiton of13edible fungus on a-glucosidase are tested and their efficacy order is Inonotus obliquus> Phellinus linteus> Lentinus edodes. The IC50value is about:Inonotus obliquus extract,0.015mg/mL; Phellinus linteus extract,0.038mg/mL; Lentinus edodes extract,2.2mg/mL. The IC50value of the positive control acarbose is4.2mg/mL, the inhibition ratio on a-glucosidase of Inonotus obliquus extract and Phellinus linteus extract is about280times and110times that of the acarbose, while Lentinus edodes extract is only2times that of the positive control.On the basis of comparison thirteen kinds of edible fungus’s a-glucosidase inhibitory activity, under the guidance of the use of biological activity-oriented separation method, the aqueous extract of Inonotus obliquus was then extracted by petroleum ether, ethyl acetate and butyl alcohol according to the polarity, successively. The inhibitory ratio of a-glucosidase inhibitory activity of every fraction was determined. The IC5o value of the petroleum ether extract, the ethyl acetate extract, the butyl alcohol extract, the ethyl alcohol extract, the rest of ethyl alcohol extract and the raw polysaccharides is0.35mg/mL,0.25mg/mL0.12mg/mL,0.15mg/mL,0.4mg/mL and0.024mg/mL respectively. It shows that the inhibition of the raw polysaccharides on the activity of a-glucosidase is stronger than the other fraction.The affect factor of the extraction technology of polysaccharides from Inonotus obliquus was studied, the most important factor is the water volume, and then is the temperature, the last one is time. The results of single factor experiments and orthogonal experiments indicated that the optimum extracting yield conditions were:50grams fungi powder was soaked with1000mL water (weight of material: weight of water1:20), extracted at temperature of100℃for2hours. The contrast of the inhibition on the activity of a-glucosidase of classification ethanol sedimentation polysaccharides showed that the affect of60%ethanol sedimentation fraction is the best one, its IC50value is10μg/mL, and on account of its high yield and good solubility, the further isolation and purification were studied. Three polysaccharides active fractions1011,1012and IO2were isolated on ion exchange chromatogram column and gel chromatogram column. Their inhibiton on a-glucosidase are tested and the results showed that the inhibitory activity on a-glucosidase of purified composition are all higher than the unpurified liquid, the inhibitory activity of active fraction IO11is the most obvious. The inhibiton of fraction O11with different concentrations on a-glucosidase are measured, its IC50o value is approximately8μg/mL. |
