Structural Characteristics, Antioxidant and Hypoglycemic Activities of Polysaccharide from Siraitia grosvenorii .

The structural characterization, the in vitro antioxidant activity, and the hypoglycemic activity of a polysaccharide (SGP-1-1) isolated from Siraitia grosvenorii (SG) were studied in this paper. SGP-1-1, whose molecular weight is 19.037 kDa, consisted of Gal:Man:Glc in the molar ratio of 1:2.56:4.90. According to the results of methylation analysis, GC-MS, and NMR, HSQC was interpreted as a glucomannan with a backbone composed of 4)- β -D-Glc p -(1→4)-, α -D-Glc p -(1→4)-, and 4)-Man p -(1 residues. α -1,6 linked an α -D-Gal p branch, and α -1,6 linked an α -D-Glc p branch. The study indirectly showed that SGP-1-1 has good in vitro hypoglycemic and antioxidant activities and that these activities may be related to the fact that the SGP-1-1's monosaccharide composition (a higher proportion of Gal and Man) is the glycosidic-bond type ( α - and β -glycosidic bonds). SGP-1-1 could be used as a potential antioxidant and hypoglycemic candidate for functional and nutritional food applications.