Extraction,Purification,Characterization And Antioxidant Activity Of Polysaccharides From Crataegus Pinnatifida Bunge

Crataegus pinnatifida Bunge,a kind of important plant resource,is a member of Rosacea family with a long edible and medicinal history in China.In recent years,C.pinnatifida has drawn rising attention due to its unique edible and medicinal value.Therefore,researches on its active components,biological activities and processing technology have shown great value and prospect.As an indispensable biological macromolecule,polysaccharides have become an important resource of drugs and health products for its significant biological activities and little side effects.Up to now,studies of C.pinnatifida were mainly focused on its flavonoids,and as far as we know,the research on polysaccharides was hard to find.In view of this,to fully develop the resource of C.pinnatifida and to provide theoretical basis for further research on polysaccharide from C.pinnatifida?CPPc?,the extraction optimization,chemical properties,structural characteristics and biological activities of it were studied.The main research results are as follows: 1 Optimization for extraction of CPPcThe effects of liquid-material ratio,enzymolysis temperature,p H value,enzyme amount,enzymolysis time and ultrasonic time on the extraction of CPPc were invested by single-factor tests.Then,a BBD-RSM test with three independent variables and three levels was used to evaluate the effects of main experimental factors on extraction yields of CPPc.Regression analysis was carried out by Design expert,and the optimal extraction conditions were as follows: liquid-solid ratio 30:1 m L/g,enzymolysis time 66 min,and enzymolysis temperature 52? and the experimental yields of CPPc was 10.39%.The extraction effects of hot water extraction,ultrasound assisted extraction,enzyme assisted extraction and enzyme-ultrasound assisted extraction were investigated and compared.The results showed that enzyme-ultrasound assisted extraction not only can reduce extraction time and organic reagent consumption,but also can improve contents of polysaccharides.Meanwhile,polysaccharides obtained by different extraction methods had insignificant influence on the characteristic functional groups and monosaccharide composition.Polysaccharides obtained by different extraction methods were all mainly consisted of rhamnose,xylose,glucose and galactose.The molecular weight of polysaccharides extracted by ultrasound was the highest,while polysaccharides from other methods were similar.2 Isolation,purification,physicochemical properties and structural characteristics of CPPcDecoloration rate and polysaccharide retention rate were chosed as indicators to evaluate the decolorization effect of AB-8 resin on CPPc.The effects of time,temperature,p H value and resin amount on decoloration of CPPc were investigated by single factor experiment.The optimum decolorization parameters were as follows: decoloring temperature 40?,decoloring time 1.5 h,p H value 5 and resin amount 0.6 g.Compared to decoloration using attapulgite,active carbon and hydrogen peroxide,decoloration by resin had better decolorizing effect.a DEAE-52 cellulose column chromatography was used for purification and three fractions?CPP-1,CPP-2 and CPP-3?were obtained.The contents of carbohydrate,protein,uronic acid and sulfate radical were measured with the method of sulfuric anthrone,Bradford,sulfuric acid-carba and ion chromatography.Then,structural characteristics of these polysaccharides were investigated and compared by gas chromatography?GC?,high performance gel permeation chromatograph?HPGPC?,ultraviolet-visible?UV?and Fourier-transform infrared?FT-IR?spectroscopy.3 Comparison of antioxidant activityThe antioxidant activities,including the lipid peroxidation inhibition activity,ABTS and superoxide radical scavenging activity,Fe²⁺ chelating activity and reducing power of crude and purified polysaccharides,were determined and evaluated.The results showed that the crude polysaccharide exhibited stronger antioxidant capacity than the purified fractions,and CPP-2 showed the strongest antioxidant capacity among the purified fractions.