Polysaccharides extraction from Erythirna variegata, chemical characterization and its antioxidant activity

The objective of this study was to determine the optimum conditions for extracting crude polysaccharides from the bark of Erythirna variegata (EVP) using response surface methodology (RSM). The quantitative effects of extraction time, temperature and the ratio of water to raw material on EVP yields were investigated using Box-Behnken experimental design. The monosaccharide composition was analyzed by 1-phenyl-3-methy-5-pyrazolone pre-column derivatization high performance liquid chromatography, and the molecular weight was measured by high performance gel permeation chromatography. The antioxidant activities were also evaluated. By solving the regression equation and analyzing the data, the optimum conditions were obtained as follows: extracting time 1.52h, extraction temperature 91.40°C, and the ratio of water to raw material at 24.78. Under these conditions, the experiment yield was 2.064%, which well agreed with the predicted value. Chemical composition analysis indicated that EVP was mainly composed of mannose, rhamnose, galacturonic acid, glucose, galactose and arabinose, and the mean molecular weight of the two major fractions was about 26.8kDa and 5.5kDa, respectively. EVP had strong scavenging activity against DPPH radicals, potential reducing power and total antioxidant activity. This study provides a scientific basis for the use of this herb in traditional medicine as an antioxidant.