Abstract:Lentinus edodes is the second largest cultivated edible fungus in the world. During its process, of Lentinus edodes stem, a large amount of Lentinus edodes stem (LES) waste is generated, which causes resource waste and environmental pollution. In this study, LES was used as the raw material, three polysaccharides, LESPs-20, LESPs-50 and LESPs-80, were obtained from LES by water extraction then purification by step gradient alcohol precipitation, and their composition and structural characteristics were analyzed by chemical methods, high-performance gel permeation chromatography, gas chromatography and infrared spectroscopy. The results showed that LESPs-50 had the highest sugar content (84.31%) and its relative molecular weight was 477.41 ku. In addition, LESPs-20, LESPs-50 and LESPs-80 all contained Man, Glc and Gal, but their molar ratios of monosaccharides differed. All the three polysaccharides were neutral heteropolysaccharides containing β-glucosidic bonds, with glucose being the main component. The LESPs were sulfated and the differences in immunomodulatory activity between the original sample and the sulfated sample were compared in depth. The results showed that the immunomodulatory activities of the sulfated polysaccharides were superior, and they could improve the cell viability, phagocytic ability, acid phosphatase activity and the amount of secreted NO of RAW 264.7 cells. The higher the content of sulfate group, the better the immunomodulatory activity. The results of this study will provide a theoretical basis for the high-value development and utilization of the Lentinus edodes stem.
