Characterization of a Novel Polysaccharide from Tetraploid Gynostemma pentaphyllum Makino

A novel heteropolysaccharide (GPP-TL) was isolated from tetraploid Gynostemma pentaphyllum (Makino) leaf by hot water extraction and anion exchange and gel permeation chromatography approaches. GPP-TL had a molecular weight of 9.3 x 10(3) Da and was primarily composed of glucose, galactose, and arabinose, with a molar ratio of 43:5:1, respectively. The chemical structure of GPP-TL was characterized using chemical and instrumental analyses. The results indicated the presence of (1 -> 4)-alpha-D-glucopyranosyl, (1 -> 4)-beta-D-galactopyranosyl, (1 -> 4,6)-linked-alpha-D-glucopyranosyl, and terminal 1 ->)-alpha-D-glucopyranosyl moieties in a molar ratio of 5.7:1:1.5:1, respectively. The results indicated that GPP-TL had glucose and galactose residues in the main chain with (1 -> 6)-linked branches at glucose residues. In addition, GPP-TL exhibited scavenging capacities against hydroxyl, peroxyl, and DPPH radicals in vitro and had a stronger bile acid binding ability than psyllium on a same weight basis.