Characterization, hypoglycemia and antioxidant activities of polysaccharides from Rhodosorus sp. SCSIO-45730

In this study, three new and highly purified water-soluble polysaccharides fractions (RSP-1, RSP-2 and RSP-3) were isolated from Rhodosorus sp. SCSIO-45730 with varying chemical compositions. All samples were polysaccharides with non-triple helical structure, in which RSP-1 mainly contained 1,4-linked Galp, 1,3,6-linked Galp and t-Glcp, while RSP-2 and RSP-3 were 1,4-linked Galp, 1,4,6-linked Galp and t-GalAp. The three polysaccharides all exhibited different morphology features, but they presented random coil configurations, which contained lots of pyranoid polysaccharides with α/β glycosidic bonds. RSP-1 possessed stable thermal property and good emulsifying property. The hypoglycemic assays demonstrated that RSP-2 exerted the strongest inhibitory activities on α-amylase (IC50 =0.56 mg/mL) and α-glucosidase (IC50 =0.05 mg/mL) with mixed-typed inhibition and competitive inhibition, respectively. Meanwhile, the antioxidant activities revealed that RSP-1 and RSP-3 exhibited marked effects.