Purification, partial characterization and antioxidant activity of polysaccharides from Glycyrrhiza uralensis

Glycyrrhiza uralensis, an important Chinese medicine, has a long history of use in China. In this study, three water-soluble polysaccharides fractions (GUPs-1, GUPs-2 and GUPs-3) were isolated and purified from the root of G. uralensis by DEAE-52 and Sephadex G-100 column chromatography. Physicochemical properties and antioxidant activities of the three purified polysaccharides were investigated. The molecular weights of GUPs-1, GUPs-2 and GUPs-3 were 10,160, 11,680 and 13,360 Da, and the ratios of glucose were 23.4%, 14% and 1.13%, respectively. The antioxidant activities of the three purified polysaccharides followed the order: GUPs-1>GUPs-2>GUPs-3. GUPs with lower molecular weight and higher ratio of glucose, basically exhibited higher antioxidant activities at the same concentration. This indicated that the molecular weight and the ratio of monosaccharide composition of the GUPs could affect the antioxidant activities.