Extraction, Isolatio, Purification, Structural Elucidation And Antioxidant Activity Of Polysaccharides From The Fruting Bodies Of Pleurotus Eryngii

There are three parts in this research including the optimization of ultrasonicextraction technology of Pleurotus eryngii polysaccharide using response surface analysis and antioxidant activity, purification, physical-chemical character research and sugar structure elucidation.The software of Design-Expert was used to determine the optimum conditions of Pleurotus eryngii polysaccharide (PEPS) extraction. Results showed that the response surface was suitable for the optimization of PEPS extraction and the optimal extractive techniques were as follows: extraction time 40 min, ultrasonic power 520 w, the ratio of water to material 20, and the PEPS extracting yield reached 34.3% under the conditions. PEPS were extracted under the conditions, precipitated into different crude polysaccharide PEPS30, PEPS60 and PEPS80 by different degree of ethanol, which were also tested for their antioxidant activity. The results showed that PEPS80 possesed the best reducing power, DPPH radical scavenging ability and oxygen radical scavenging ability, PEPS60 is better than PEPS30.PEPS60 was purified using DEAE Sapharose Fast Flow and Sephacryl S gel-filtration chromatography repeatedly. Two water-soluble homogeneous polysaccharides PEPSI and PEPS2 were obtained. IR spectra showed that the sugar characteristic peaks were existed. HPLC producing a single symmetrical peak, indicated that each of them was homogeneous and their molecular weight were 1.88×104 Da and 1.77×106 Da.PEPSI was investigated by sugar analysis, methylation analysis and NMR spectroscopic methods to confirm the sugar composition, the number of sugar residues and the form of glycosyl linkage. PEPS1 composed of galactose,3-O-Me-galactose and mannose. And the methylation showed that the galactosyl residues are mainly 1,2,6-linked with a monor of 1,2,3,6-linked units. The 3-O-Me-galactosyl residues are mainly 1,6-linked with a minor of terminals-linked units. The mancosyl residues are mainly terminal residues and a small amount of 1,4-linked units. With the NMR analysis, it showed that galactose were existed as a configuration, mannose as β configuration.PEPS2 was investigated by sugar analysis and showed that it was composed of mannose and glucose with the molar ratio of 1 : 10.3. And the methylation showed that the gluctosyl residues are mainly 1,2,6-linked and 1,6-linked with a minor of terminal-linked. The manctosyl residues are mainly 1,6-linked.