Extracting,Structure Analysis And Antioxidant Activity Of A Polysaccharide From Siraitia Grosvenorii

Siraitia grosvenorii is a traditional Chinese medicinal food,which has good medicinal value and health function.Siraitia grosvenorii polysaccharide is one of the important active ingredients of Siraitia grosvenorii,which has anti-oxidation,anti-tumor and hypoglycemic.At present,there are few studies on the purification,structure and biological activity of Siraitia grosvenorii polysaccharide.Therefore,This study optimized the extraction conditions of Siraitia grosvenorii polysaccharides.The main aims of this study is to elucidate the structure and antioxidant activity of this polysaccharide.Using Siraitia grosvenorii dry powder as raw material,the extraction process of Siraitia grosvenorii polysaccharide was optimized by single factor and orthogonal test,and the experimental results show that the optimal extraction conditions:water extraction temperature is 70?,time is 3 h,ratio of material liquid is 1:35(g/mL).By using this condition test,pholiota Siraitia grosvenorii polysaccharide reached 14.55±0.10%.The Siraitia grosvenorii polysaccharide was through hot water method leached,ethanol precipitate,except protein,except pigment,vacuum freeze drying,and purifie d by Sephadex G-200 and ultrafiltration to obtain pure polysaccharide,named SGP.The content of polysaccharide was examined to be 93.49±0.21%with phenol-sulfuric acid method;The content of glucuronic acid was 36.30%.Its average molecular w eight was estimated to be 1.93×103 kDa by High Performance Gel Permeation Chrom atography(HPGPC).Monosaccharide analysis showed that SGP was composed of ar abinose:mannose:glucose:galactose:glucuronic acid:galacturonic acid=1:1.92:3.98:7.63:1.85:7.34.After investigated by specific rotation determination,FT-IR,periodate o xidation,Smith degradation,methylization analysis,The optical rotation of SGP was+1600 and the main glycoside bond was linked by?4)-?-D-Galp-(1?,?4)-?-D-Gal pA-(1?and?3,6)-a-D-Glcp-(1?while the branches were comprised of?4,6)-?-D-M anp-(1?,?2)a-D-Araf(1?,?-D-Araf-(1?,?-D-Galp-(1?and ?-D-GlcpA-(1?.In vitro antioxidant results suggested that SGP was processed with certain scavaging capacity against DPPH radical,Hydroxyl radical and Superoxide radical.A highest inhibition rate of 93.49±0.21%was observed against DPPH radical.