Structural Elucidation and Antioxidant Activity of a Polysaccharide from Mycelia Fermentation of Hirsutella sinensis Isolated from Ophiocordyceps sinensis

摘要

The structure and antioxidant activity of a polysaccharide from mycelia fermentation of Hirsutella sinensis were analyzed. The natural active component water-soluble polysaccharides was isolated from mycelia, and three polysaccharide fractions HSP-1, HSP-2, and HSP-3 were purified with chromatography and the structures were identified. The structural characteristics determination with a combination of chemical and instrumental analysis methods showed that the mainly component HSP-1 was about 1.7×104 Da, and composed of glucose, mannose and galactose at a molar ratio of 4.5:1.0:1.4. Further researches revealed that HSP-1 was a branched polysaccharide possessing a backbone of (1→4)-α-D-glucose residues (~70%), (1→4)-α-D-mannose residues (~15%) and (1→4)-α-D-galactose residues (~15%). The branches were at the (1,2,4,6→)-α-D-glucose residues (~8%) of the backbone, mainly composed of (1→4)-α-D-glucose residues, (1→4)-α-D-galcatose residues, (1→4)-α-D-mannose residues, and terminated with α-D-galactose residues. The in vitro antioxidant assay proved HSP-1 possessed the hydroxyl radical-scavenging activity with an IC50 value of 0.834 mg/mL.