Structural Characterization And Immunomodulatory Activity Of Sulfated Polysaccharide From Grifola Frondosa

The medicinal and edible fungi, Grifola frondosa, is rich in nutritional value. Grifola frondosa polysaccharides showed superior anti-virus, anti-cancer and immunomodulatory activity as a biological macromolecules active substance. Water-insoluble polysaccharides, which occupied a larger proportion of fruiting bodies polysaccharides, were sulfated to get a good solubility in water. Sulfated polysaccharides could increase and improve water-insoluble polysaccharides biological activity as well as achieve the full advantage of Grifola frondosa polysaccharides resources.In this study, the alkali extraction and acid precipitation were used to extract water-insoluble polysaccharides from Grifola frondosa fruiting bodies. A white Grifola frondosa polysaccharide fraction GFP was obtained after further isolated and purified, with 96.83% of the average total sugar content, trace amounts of protein and uronic acid, free of sulfuric acid group and nucleic acid. Instrumental analysis methods(UV, IR, GC, GC-MS, NMR spectroscopy) and chemical analysis methods (acid hydrolysis, periodate oxidation, Smith degradation, methylation) were used to characterize the structure of GFP, showed that GFP was a-D-pyranose polysaccharide, which composed of rhamnose, xylose, mannose, glucose with molar ratio of 1.00:1.04:1.11:6.21. Glcp residues accounted for 83% sugur units of GFP, every two (1�'3)-Glcp and one (1�'3,4)-Glcp connected interval in the main chain with a small amount of 1�'1 �'4,1�'6 glycosidic linkage.Sulfated group location, degree of substitution, molecular weight and physicochemical properties were closely related to sulfated polysaccharides bioactivity. A water-soluble sulfated polysaccharide S-GFP was prepared by GFP using sulfur trioxide trimethylamine-DMF method, which the average total sugar content was 60.04%, the DS (mainly for the C6-substituted, existed di-substituted) of sulfate groups was 1.42, and the molecular weight was 155 kDa. In a certain range of concentrations and action time, S-GFP could improve the proliferation and phagocytic activity of RAW264.7 cells significantly, enhance the metabolic ability of cell nucleic acids and glycogen, increase the production of cell enzymes (acid phosphatase, lysozyme, superoxide dismutase) as well as NO, and stimulate the secretion of cytokines (IL-2、IL-12、IFN-γ、IL-6).