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

Abstract

The structural characterization, the in vitro antioxidant activity, and the hypoglycemic activity of a polysaccharide (SGP-1-1) isolated from <i>Siraitia grosvenorii</i> (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)-<i>β</i>-D-Glc<i>p</i>-(1→4)-, <i>α</i>-D-Glc<i>p</i>-(1→4)-, and 4)-Man<i>p</i>-(1 residues. <i>α</i>-1,6 linked an <i>α</i>-D-Gal<i>p</i> branch, and <i>α</i>-1,6 linked an <i>α</i>-D-Glc<i>p</i> 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 (<i>α</i>- and <i>β</i>-glycosidic bonds). SGP-1-1 could be used as a potential antioxidant and hypoglycemic candidate for functional and nutritional food applications.