Physicochemical characterization, potential antioxidant and hypoglycemic activity of polysaccharide from Sargassum pallidum

A polysaccharide, designated as PSP-1, was isolated and purified from Sargassum pallidum. Physicochemical characterization showed that PSP-1 with the average molecular weight of 1.036 × 106 Da was composed of fucose, arabinose, galactose, glucose, xylose, mannose, galacturonic acid and glucuronic acid in a molar ratio of 18.45:2.15:19.06:1.89:16.07:1.00:5.74:20.09. The results of antioxidant assays indicated that PSP-1 had good DPPH radical scavenging activity, hydroxyl radical scavenging activity, cellular antioxidant activity, and reactive oxygen species inhibition activity, and could significantly improve cellular antioxidant enzymes of ABAP-induced HepG2 cell model. The results of hypoglycemic assays showed that PSP-1 possessed favorable α-amylase and α-glucosidase inhibitory activities, and could remarkably enhance glucose consumption, glycogen synthesis and the activities of pyruvate kinase and hexokinase in insulin-resistance HepG2 cells. The results suggest that PSP-1 can be exploited as a potential antioxidant and hypoglycemic candidate for functional and nutraceutical applications.