Separation, Purification Of Polysaccharides From Taxus Mairei And Its Extraction Kinetics

The extraction of polysaccharides by hot water from the leaves of Taxus mairei was first studied to get the optimal extraction conditions. Single-factor test and the orthogonal experiments L9(3⁴) showed that extraction yield of polysaccharides were differently affected in sorted order by three factors: material-water ratio＞temperature＞extraction time. Analysis of variance showed that material-water ratio and temperature were significant factors. Considering the efficiency and energy consumption, the optimum conditions of polysaccharides extraction were 1:25(material-water ratio), 150min and 90℃, the extraction yield of polysacchrides was 11.9%.IR spectra of rude polysaccharides in water extraction liquid indicated that they were acidic pyranopolysaccharides. The density gradient ultracentrifugation separated rude polysaccharides into four bands, suggesting four different components. Super molecular weight of components was first removed from rude polysaccharides by 50% ethanol precipitation. A fraction of polysaccharides from the supernatant was collected by Sepherose 6 Fast Flow gel column chromatography and named TM-1. Its optical rotation degree was +65.3°at 25℃. HPGPC proved it to be a pure component with average molecular weight(Mw) of 317000 Da. After completely hydrolyzing by H₂SO₄ into monosaccharides, TM-1 was proved by HPLC to be composed of seven monosaccharide: D-fucose, D-glucose, rhamnose, D-xylose, D-mannose, D-galactose and L(+)-arabinose. Among them, D-xylose was the most(41.47%) and D-galactose was the second(19.77%).Based on analysis of the process of polysaccharides extraction by hot water, a extraction model was set up. The model fitted the experimental data well.