Abstract: Objective: This study aimed to optimize the neutroproteinase-assisted extraction of polysaccharides from the stroma of Shiraia bambusicola Henn using response surface methodology (RSM) and to investigate the separation, purification, characterization and antioxidant activity of the polysaccharides. Methods: The effects of extraction time, enzyme concentration and extraction temperature on the yield of polysaccharides were examined by using one-factor-at-a-time experiments. These extraction conditions were optimized through mathematical modeling. The crude extract was fractionated into two fractions: SBH-1 and SBH-2, with SBH-1 being among them. The monosaccharide composition, molecular mass and structure of SBH-1 were detected by high performance gel permeation chromatography (HPGPC) and infrared spectroscopy, respectively. The in vitro antioxidant activity was measured in comparison with VC by superoxide anion scavenging, 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging, and lipid peroxidation inhibition assays. Results: The maximum yield of crude polysaccharides of 7.63% was obtained at 115.95 min of extraction at 46.68 ℃ with 0.83% neutral proteinase. The molecular mass of SBH-1 was determined to be 18.3 kD, and its monosaccharide composition consisted of glucose, mannose, and galactose with a ratio of 1.3:2.3:1.2. The EC50 values for scavenging of DPPH and superoxide anion radials were 2.03 and 1.038 mg/mL respectively. Conclusions: The neutroproteinase-assistant extraction procedure was simple and easy to operate. SBH-1 was a neutral heteropolysaccharide with high activity. This study can provides a theoretical basis for further research and development of polysaccharides from S. bambusicola Henn.

Key words: Shiraia bambusicola Henn, polysaccharide, response surface methodology, antioxidant activity