Abstract:Using dandelion as the raw material，the crude polysaccharide was extracted from dandelion with ultrasonic assisted method.The decolorization and deproteinization process of crude polysaccharide were investigated and hypoglycemic activity of polysaccharides was evaluated in vitro.Based on decolorization and polysaccharide loss rate，a suitable method was selected by comparing macroporous resin method，activated carbon method，hydrogen peroxide method and chitosan method.Then，four methods were used to select the optimal deproteinization method with the rate of deproteinization and polysaccharide loss as indexes，including Sevag method，salting out method，enzyme-trichloroacetic acid（TCA）method and enzyme-Sevag method.Results indicated that the method of polar macroporous resin S-8 had the ideal decolorization effect，the decolorization rate and polysaccharide loss rate was 86.45 % and 18.9 %，respectively.Deproteinization was best achieved through salting out method，the rates of deproteinization and polysaccharide loss were 85.64 % and 20.51%，respectively.The purified polysaccharides possessed inhibiting capacity against α-glucosidase with a dose-dependent relationship.The concentration of 1.0 mg/mL inhibited 76.28%α-glucosidase.