Separation,Purification,Structural Elucidatuion And Antioxidantion Of Polysaccharides From The Fruting Bodies Of Boletus Edulis Bullex Fr.

Boletus edulis(Boletus edulis BulLex Fr.),when it cooked, it has tender flesh, abundance of delicious and unique flavor. Because of these advantages it was always deeply respected by the people and the ancients termed the "delicacies". It contained a variety of nutrients such as protein, vitamins, amino acids, polysaccharides and calcium, iron and other trace elements which are important in the human body. It is reported that B.edulis exhibited some certain biological activities.At present, most of researches on B.edulis were focused on the nutritional element and process research about the extraction and separation of polysaccharides, but the study on separation, purification and structure identification of polysaccharides have not been reported. In order to investigate the chemical structure and antioxidant activities of polysaccharides from B.edulis, the extraction, antioxidant activities, isolation, purification, structural elucidation of polysaccharides from B.edulis were carried out.There are three parts in this dissertation. Studies on extraction, separation, antioxidant screening, physic-chemical character, structural analysis of polysaccharides from the fruiting bodies of B.eduIis were discussed in this dissertation.The fruiting bodies of B.edulis were degreased by 95% ethanol. The polysaccharide fractions were obtained by extraction with hot water. Using alcohol precipitation and antioxidant activity screening, the polysaccharide content of BFPF60 was the second most of them. In antioxidant activity study, BEPF60 showed inhibitory effects on superoxide radical and hydroxyl radical were the highest, and its reducing power and chelating activity were the more significant, so BEPF60 was selected to be further separation and purification.Two water-soluble homogeneous polysaccharides (BEPF1, BEPF2) were purified and obtained by using anion-exchange chromtography (DEAE Sepharose Fast Flow) and gel-filtration chromatography (Sephacryl S-300) from BEPF60. HPLC producing a single symmetrical peak indicated each of them was homogeneous and their molecular weight were 1.08×104 Da and>2.00×106 Da, respectively (BEPF1, BEPF2). Lack of absorption at 280nm and 260nm by UV scanning indicated that they contained no protein and nucleic acid.The structure of BEPF1 was investigated using IR, GC analysis, GC-MS analysis and NMR spectroscopic methods (1D NMR:1H NMR, 13C NMR; 2D NMR:’H-’H COSY, TOCSY, HMQC, NOESY and HMBC spectra). GC analysis showed this polysaccharide was composed of L-fucose, D-mannose, D-glucose and D-galactose in the ratio of 0.21:0.23:1.17:1.00. GC-MS analysis revealed the primary structure of polysaccharide BEPF1 mainly consisted of 1-substituted-Fucp、 1-substituted-Glcp、1,6-disubstituted-4-O-Me-Glcp、 1,6-disubstituted-Glcp、1,6-disubstituted-Ga1p、1,2,6-trisubstituted-Manp and 1,2,6-trisubstituted-Galp in the ratio of 0.43:1.00:0.28:1.98:0.31:1.31. NMR analysis further showed the structure of BEPF1 is consisted of α-D-(1�'6)-galactopyranan backbone with a terminal a-L-fucosyl unit on O-2 of the 2,6-di-O-substituted-D-galactosyl units, β-D-(1�'6)-4-O-Me-glucopyranan and β-D-(1�'6)-glucopyranan backbone with a terminal β-D-glucosyl unit and it also contained a minor of 1,2,6-p-D-Mannopyranan residues.GC analysis of BEPF2 showed that it was composed of L-fucose, D-xylose, D-mannose, D-glucose and D-galactose with the molar ratio of 0.66:1.00:3.46:2.37:2.36.