余甘水溶性多糖的分离和性质研究

he crude polysaccharides from Phyllanthus Emblica were obtained with the water extraction and alcohol precipitation method, and then were separated by freeze-thawing, depigmenting, protein removing, dialysing and gel filtrating steps. The chemical composition was determined. The purity and molecular weight distribution of polysaccharides were analyzed by high performance size exclusion chromatography (HPSEC). The derivative method which could accurately analyzed aldose and sugar acid was built up and the monosaccharide composition and molar ratio of polysaccharides were measured by GC-MS. By infrared spectrum the polysaccharide structure was preliminarily analyzed. The purity of the polysaccharides by extraction and isolation was 99.04% and the chemical composition consisted of neutral sugar, uronic acid and a very small amount of protein. Two kinds of polysaccharides A and B were detected, accounting for 93.64% and 6.36% of the total amount and with predicted molecular weights of 1.3×105 Da and 1.4×104 Da, respectively. The infrared spectrum exhibited the absorption peak of uronic acid, which showed that it was a pectic polysaccharide mainly containing α-glycosidic bond. The polysaccharide was composed by different sugar residues, among which the molar ratio of galacturonic acid, galactose, rhamnose and arabinose was 3.21:6.59:1:0.23. In addition, there were still a lot of glucose and xylose and a small amount of mannose. The polysaccharides were successfully isolated from Phyllanthus Emblica, which contained pyran aldose of α configuration and was a mixture of pectin polysaccharide and hemicellulose.