System Separation And Purification Of Water-soluble Green Tea Polysaccharides And Study On Their Immunological Activities And Scavenging Effects Of Hydroxyl Free Radical Activities

Becauses of various kinds of biological activities, more attection was paid to the polysaccharide. To screen polysaccharide components with high activity of immunity and scavenging bioability of hydroxy free radical, water-soluble green tea polysaccharides were separated and purified by ultrafiltration membranes with pore diameter of 150kD,20kD,6kD in turns. three parts of trapped fluids with molecule weights of 150kD,20kD,6kD were obtained. Meanwhile the alkali tea residue was treated to compare the differences of the physical and chemical properties and immune activity between water-soluble green tea polysaccharide and alkali-soluble green tea polysaccharide.All the three fractions and alkali-soluble green tea polysaccharide were further separated and purified by DEAE-cellulose ion-exchange chromatography and propylene glucosan gelatin Sephacryl S-300 column chromatography.Their purity and molecular weight distribution were determined with high performance gel permeation chromatography(HPGPC) equipped with ELSD detector, and the mouse macrophage cell line Raw264.7 immune detection and clearance activity of the hydroxyl radical activity of the classification component were determined. The results showed that more than 50 percent of dry matter could permeat the ultrafiltration membrane with aoerture of 20kD, while the content of 20kD membrane trapped fluid was the highest, the proportion of dry matter can reach 36.86%, the content of withholding part of the polysaccharide of 150kD membrane and 6kD membrane was 27.13% and 21.16% respectively, while the 6kD membrane of the stem in part of the content of only 1.09%. Thus, ultrafiltration membrane separation technology could be used to separate and purify polysaccharide and other compounds in tea. After systematic gradation, more than 20 components of water-soluble green tea polysaccharide altogether were obtained.Their purity and molecular weight distribution were determined with high performance gel permeation chromatography (HPGPC) equipped with ELSD detector, and 7 components of homogeneous water-soluble polysaccharides and two components of homogeneous alkali-soluble polysaccharides were obtained. The immunological activities of these green tea polysaccharides were determined by stimulated phagocytosis and nitric oxide production on RAW264.7 macrophage cell line of mice. Results showed that tea polysaccharides with 20kD MW possessed significant immunological activities on NO production or phagocytosis of mice macrophage Raw 264.7 cells, the tea polysaccharides component mostly concentrate at 6kD MW, the part polysaccharides with 20kD MW had the strong scavenging ability of hydroxy free radical, but the immunity activity of alkali-soluble polysaccharide was relatively low.