Purification and structural characterization of Chinese yam polysaccharide and its activities

Purification and structural characterization of Chinese yam polysaccharide were investigated and its activities were analyzed. Results indicated that a single component polysaccharide with a molecular weight of 16,619 Da was obtained after hot water extraction with sequential sevage deproteinization, HSCCC and Sephadex G-100 size-exclusion chromatography. The FTIR analysis showed that it had characteristic absorptive peaks and contained uronic acid. The methylation and GC–MS analysis showed that it comprised of glucose and galactose with a molar ratio of 1.52:1, and that it mainly contained 1,3-linked-glc, 1-linked-gal and 1,6-linked-gal glycosidic bonds. 1H NMR and 13C NMR spectra analysis showed that there were two α-configurations and one β-configuration, and that β-1,3-glucose, α-1-galactose, α-1,6-galactose might exist in the structure of the purified polysaccharide. The determination of the antioxidative activity showed that it could scavenge hydroxyl and superoxide radicals. The purified polysaccharide displayed a certain inhibitory activity against Escherichia coli, with a MIC of 2.5 mg/mL.