Physicochemical, rheological properties and in vitro hypoglycemic activities of polysaccharide fractions from peach gum

In this study, peach gum was sequentially extracted by water at 25 °C, 95 °C and 0.1 M NaOH, obtaining room temperature water-soluble (PG-WE), hot water-soluble (PG-HWE), and alkali-soluble (PG-AE) polysaccharide fractions. These three kinds of polysaccharide fractions exhibited a similar arabinogalactan structure according to FTIR spectrum and monosaccharide composition. However, their molecular weight and chain conformation were different based on high-performance size exclusion chromatography analysis, which resulted in different rheological behavior. PG-WE and PG-HWE presented non-Newtonian behavior, and the apparent viscosity of PG-WE was higher than that of PG-HWE at concentrations of 2.0 % and 3.0 % (w/w). Dynamic sweep tests showed that PG-HWE solutions behaved as viscous fluids, while PG-WE solutions tended to form gel-like structures at concentrations higher than 2 % (w/w). Furthermore, PG-WE showed significant in vitro inhibition against α-glucosidase activity in a dose-dependent manner and reduced the fluorescence of α-glucosidase through dynamic quenching mechanism.