Purification, Characterization and Immunological Function of a New Polysaccharide-protein Complex (LE) from Cultured...

LE was obtained through extraction of cultured mycelia of Lentinus edodes by hot water, ethanol, and Sevag method, followed by the purification by DEAE-cellulose column chromatography. LE was proved to be homogeneous by DEAE-cellulose column chromatography, UV spectroscopy and polyacrylamide gel electrophoresis. As identified by IR and UV, it was a polysaccharide-protein complex, with the molecular weight of about 5.08x10(5) by light diffusion method, and contained 94.2% carbohydrate and 5.8% protein. Complete acid hydrolysis revealed that its carbohydrate moiety was composed of glucose only and its protein portion consisted mainly of Asx, Glx, Ala and other amino acids. The structure of carbohydrate moiety was determined by methylation, hydrolysis, acetylation, TLC, (1)H NMR etc. and was shown that it consisted of 2,4-di-O-Me-Glu, 2,4,6-tri-O-Me-Glu, 2,3,4,6-tetra-O-Me-Glu, at a ratio of about 1:2:1. The results suggested that LE had a beta-(1right curved arrow 3)-D-glucan backbone with beta-(1right curved arrow 6)-D-glucose side chains. Furthermore, RT-PCR was used to analyze cytokine gene expression and bioassay was used to analyze cytokine production in the human peripheral blood mononuclear cells untreated and treated with LE. By treatment of LE, the expression level of IL-2 and TNF-alpha genes were increased in the treated human peripheral blood mononuclear cells. These results suggest that LE may induce some immune responses.