Morphological and structural characterization of a polysaccharide from Gynostemma pentaphyllum Makino and its anti-exercise fatigue activity

The crude polysaccharide was obtained from Gynostemma pentaphyllum Makino by water extraction followed by ethanol precipitation. The polysaccharide was successively purified by chromatography on DEAE-52 and SephadexG-150 column, and three polysaccharide fractions were obtained and termed GPP1-a, GPP2-b, and GPP3-a, respectively. The administration with GPP1-a markedly prolonged exhaustive exercise time of the mice. Structural features of GPP1-a were investigated by a combination of instrumental and chemical analyses, including atomic force microscope (AFM), scanning electron microscope (SEM), partial acid hydrolysis, periodate oxidation, Smith degradation, methylation analysis, gas chromatography-mass spectrometry (GC-MS) analysis and NMR spectroscopy. The results indicate that GPP1-a has a backbone of (1 -> 4)-linked alpha-D-Glucose residues. which occasionally branches at O-6. The branches are mainly composed of (1 -> 6)-linked alpha-D-Glucose, (1 -> 3)-linked beta-D-Galactose and (1 -> 6)-linked alpha-Galactose residues, and terminated with P-D-Galactose residues and P-L-Arabinose residues. (C) 2008 Elsevier Ltd. All rights reserved.