Physicochemical properties, antioxidant activities and α-glucosidase inhibitory effects of polysaccharides from Evodiae fructus extracted by different solvents

In this study, polysaccharides from Evodiae fructus were extracted by water, 0.5 M HCl, 0.5 M NaOH, water + 0.5 M HCl and water + 0.5 M NaOH, which were named as ERP-W, ERP-AC, ERP-AK, ERP-W-AC and ERP-W-AK, respectively. Their physicochemical properties, antioxidant activities and α-glucosidase inhibitory effects were investigated and compared. Physico-chemical analysis showed that they were acidic heteropolysaccharides, which had α- and β-configurations. ERP-W, ERP-AK and ERP-W-AK were mainly composed of Rha, Ara, Gal, Glc and Gal-UA, while ERP-AC and ERP-W-AC were dominantly made up of Rha, Gal and Gal-UA. ERP-AK had the highest yield (24.5%) and the best thermal stability, ERP-AC and ERP-W-AC showed better homogeneity and lower molecular weight (83.6 and 41.6 kDa), and ERP-W possessed the highest neutral sugar content (50.7%) and molecular weight. Biological evaluation indicated that ERP-W, ERP-AK and ERP-W-AK had relatively stronger antioxidant activities, including ABTS, DPPH, OH and O₂^- radicals scavenging activities, Fe²⁺ chelating ability and α-glucosidase inhibitory effects. Moreover, these actions were considerably related to their physicochemical properties especially monosaccharide composition and molecular weight. Therefore, polysaccharides extracted by water and alkaline solvents from Evodiae fructus could be developed as promising natural antioxidants and α-glucosidase inhibitors in the food and medicine industries.