Study On Extraction, Separation And Purification, Antioxidant Activity Of Polysaccharide From Pyrus Bretschneideri Rehd

Polysaccharide is a kind of high molecule compound, which is comprehensive distributing in nature. Polysaccharides is not only the energy resource or fabric materials, but also it has the informational function that can compare with nucleic acid and protein, it also has the biological function that participate in every life activity, antivirus, ant infection, resist radiation and so on. Pyrus bretschneideri Rehd has large grow area in sinkiang, and there has a great losing in fore-and-aft of picking, so extracted Polysaccharides from Pyrus bretschneideri Rehd has extensive exploder foreground based on economy and decrease the resource losing. In this paper, we studied the change of Pyrus bretschneideri Rehd polysaccharides in fore-and-aft of picking and preservation; we also studied the effects of microwave-assisted solvent extraction, ultra high pressure(UHP) extraction and ultrasound-assisted solvent extraction methods extracting Polysaccharides from Pyrus bretschneideri Rehd. The extracting of polysaccharides from Pyrus bretschneideri Rehd was precipitated by ethanol. Polysaccharide is purified by n-butanol,20%trichloroacetic, n-butanol-20% trichloroacetic method to remove protein, and then followed by DEAE-52 column chromatography. Polysaccharide is shown to be a single homogeneous component by HPLC and SephadexG-100 column chromatography. the ant oxidation activities of polysaccharides is studied. The results showed that:(1) The tests were optimized through good single factor selecting and Response Surface Methodology. The predicted values were obtained by equation very well. The microwave-assisted extraction process optimal conditions are:The extraction time 4 min, solid/liquid rate of 1:4, microwave power is 500 W; the yield of polysaccharides is 5.01%. The ultrasound-assisted solvent extraction optimal conditions are:The extraction time 65min, solid/liquid rate of 1:3, ultrasound power is 130 W, temperature is 53℃, The yield of polysaccharides is 5.03%. The UHP extraction optimum conditions were determined as follows:UHP pressure 250 MPa, temperature 50℃, UHP time 4 min, solid/liquid rate of 1:3. The yield of polysaccharides is 5.37%.(2) There have a certain change rule of the polysaccharides content in Pyrus bretschneideri Rehd. The results showed that:the polysaccharides content was reached the largest in Pyrus bretschneideri Rehd at 25th August, and then declined.(3) The extracting of polysaccharides from Pyrus bretschneideri Rehd were precipitated by ethanol. Polysaccharide is purified by n-butanol,20%trichloroacetic, n-butanol-20% trichloroacetic method to remove protein, and compared with this three methods. The results showed that:it is the best way to remove protein from Polysaccharide using n-butanol-20% trichloroacetic method, the polysaccharides losing rate is 34.85% and the protein removed rate is 13.75%.(4) The polysaccharides that has been removed protein followed by DEAE-52 column chromatography, and we obtained two kinds of polysaccharides. And they are shown to be two single homogeneous components by HPLC and SephadexG-100 column chromatography.(5) The antioxidative activities of polysaccharides are studied for two kinds of polysa-ccharides. The results showed that:this two kinds of polysaccharides are all have strong radical scavenging activity towards-OH and O2-·.The capacity of scavenging free radicals of Pyrus bretschneideri Rehd polysaccharides showed linear connections with the concentration.