Extraction and properties of Ginkgo biloba leaf polysaccharide and its phosphorylated derivative

An acid heteropolysaccharide (GBLP-3) with high purity was isolated from Ginkgo biloba leaves. It was phosphorylated to obtain the phosphorylated polysaccharide P-GBLP-3. The structure of GBLP-3 was studied. The physicochemical properties and antioxidant activities of GBLP-3 and P-GBLP-3 were compared. The results showed that GBLP-3 was mainly consisted of mannose, rhamnose, glucuronic acid, galactose and arabinose in a mole ratio of 1.00:1.34:0.69:0.97:0.62. P-GBLP-3 had the same monosaccharide composition, but the mole ratio was 1.00:0.96:0.70:0.51:0.21. GBLP-3 was a complex acidic polysaccharide with mannose, rhamnose and galactose as the core main chain and a large number of branched chains. Neither GBLP-3 nor P-GBLP-3 had the triple-helical structure. They could inhibit hydroxyl radical, DPPH radical and lipid peroxidation in a dose-dependent manner. After phosphorylation modification, the antioxidant activity of polysaccharide was significantly improved. This laid the foundation for the research and development of Ginkgo biloba leaf polysaccharide.