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Extraction and Purification of Polysaccharides from Mulberry Leaves

Author: LinJiangBo
Tutor: LiShuFen
School: Tianjin University
Course: Chemical processes
Keywords: mulberry leaves polysaccharide extraction separation purification
CLC: TQ461
Type: Master's thesis
Year: 2007
Downloads: 343
Quote: 0
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Abstract


According to modern pharmacological research,the polysaccharides from mulberry leaves can cure Alloxan-induced Diabetic Mice. Therefore, extraction and purification of the polysaccharides and study of its structure and property are technically significant and practically valuable to develop a new drug curing diabetes. The extraction of bioactive substances from mulberry leaves with water followed by precipitation with ethanol was investigated in this paper. The bioactive substances, which are useful to decrease the blood sugar, are most water-soluble and neutral polysaccharides. The extracts were further purified to increase the content of polysaccharides which was determined by anthracenone-sulphuric acid method.Firstly, the polysaccharides of mulberry leaves were extracted by hot water. The influences of extraction temperature and operation number on polysaccharide yield were investigated to get an optimal extraction conditions. Under the optimal extraction conditions the recovery ratio of total polysaccharides was 94.56%. In ethanol precipitation process, the influences of pH of solution and ethanol concentration on precipitation effect were also investigated to obtain an optimal precipitation conditions. Under the optimal extraction conditions, the content of polysaccharides is 11.48% and the extraction yield of polysaccharides is 11.10mg/g crude drug.Secondly, purification of polysaccharides using natural clarifying agents of ZTC1+1 was also investigated. Orthogonal test method was used to optimize the process. Under the optimal extraction conditions, the retention ratio of polysaccharides is 96%, the removal ratio of protein is 16% and the average content of polysaccharides is 22%, which are 2.26, 2 and 1.8 times fold respectively compared to that of the ethanol precipitation process indicating that the process is obviously superior to the ethanol precipitation process.Moreover, comparison of the different purification methods for the polysaccharides of mulberry leaves was also studied. Savage method to remove protein on the content of protein and polysaccharides was investigated. The results showed that there was only 2% protein in the extracts, which need not be removed or just need use Savage method for once. The content of ash in extracted polysaccharides was also determined. And low molecular substances were removed using ultrafiltration. Purification of polysaccharides and elimination of pigment using macroprorous resin and activated carbon were also investigated. Elimination ratio of pigment using activated carbon process is 91.72%. Elimination ratio of pigment using macroprorous resin process is 78.55% and the retention ratio of polysaccharides is higher than that of activated carbon process. Purification of polysaccharide using Sephadex was investigated preliminarily. Filtration with G-50 and then G-100 can obtain white sample, in which the content of polysaccharides is 24.85%.This research gives the necessary basic data and reference for the separation and purification of the polysaccharides of mulberry leaves.

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