Isolation Of Antioxidant Polysaccharide From Alfalfa And Its Hypoglycemic Activity

Polysaccharide is one of the important active ingredients of alfalfa.In this paper,the response surface test was used to optimize the extraction process of Alfalfa polysaccharides by alkaline hydrolysis method.The DPPH clearance rate was used as an indicator to purify the crude polysaccharide extracted from Alfalfa,Then the insulin resistance model of cell was established with 3T3-L1 adipocyte to identify hypoglycemic active components of crude alfalfa polysaccharides.1.The alfalfa powder,which was pretreated to remove pigment and protein,was used to extracted polysaccharide by an alkaline hydrolysis method.After single factor test,The optimal extraction conditions of alfalfa polysaccharide were optimized by response surface test as follow:.extraction temperature was 81.3 °C,extraction time was 2.12 h,the enzyme content was 2.03% and the alkali concentration was 10.11%.Under this condition,,the maximum yield of alfalfa polysaccharide was 19.7%,whereas the antioxidant activity of alfalfa polysaccharide was determined by DPPH to be 80.6%.2.Alfalfa polysaccharides were eluted by DEAE-52 ion exchange column chromatography to obtain three components,named APS-I,APS-II and APS-III.After eluted by Sephadex G-100,APS-II appeared a single peak.GC-MS analysis indicated that the monosaccharide composition of APS-II was xylose,galactose,glucose and arabinose with molar ratio of 0.279:0.351:0.305:0.031:0.031.The molecular weight of APS-II was 8736 KDa which determined by HPGPC.3.The insulin resistance model was constructed by using 3T3-L1 adipocytes to detect the hypoglycemic activity of alfalfa polysaccharide in vitro.The highest antioxidant activity of APS-II in the three components was 88.2%,and the hypoglycemic effect of APS-II was the best,and there was no significant difference in the effect of metformin on the concentration of 0.4 mg/m L.