Structural characterization, physicochemical properties and hypoglycemic activity of sulfated polysaccharides from Porphyra yezoensis

A sulfate polysaccharide fraction (PYSP) was extracted and purified through DEAE cellucose-52 and Sephadex G-100 from Porphyra yezoensis . The PYSP is an acidic polysaccharide with a Mw of 152.93 kDa. PYSP was composed of galactose, glucose, and Glc-UA sugars with a molar ratio of 82.38:5.02:12.59. PYSP has an irregular fragmentation structure, with a sulfuric acid group content of 43.93% ± 0.47%. It suggested that PYSP has effective cholate and cholesterol adsorption capacity, α-glucosidase inhibition activity. When the concentration of PYSP was 1.0 mg/mL, the inhibition rates of α-glucosidase were 45.02%. PYSP could decrease α-helix and increase β-fold and random curl of α-glucosidase. In addition, the in vitro hypoglycemic activities of PYSP were dose-dependent. PYSP could improve glucose consumption, glycogen synthesis, and pyruvate kinase activity in insulin-resistant HepG2 cells. These results suggested that PYSP is a novel material for functional hypoglycemic foods.