Study On Preparation And Structure Of Sweet Potato Polysaccharide

Polysaccharides have various biological activities and pharmacological effects such as anti-tumor,immune regulation,anti-oxidation,anti-viral,hypoglycemic,etc.The mechanism is usually closely related to the structure of polysaccharide.Due to the variety of polysaccharides and their complex structures,people continue to explore and study the structure,activity and structure-activity relationship of polysaccharides.Sweet potato [Ipomoea batatas(L.)Lam.] Is a one-year or perennial herb of the sweet potato genus Convolvulaceae.It is recorded in the Compendium of Materia Medica that sweet potato is flat,sweet,non-toxic,nourishing,strengthening the spleen and stomach,and tonic.Strong kidney yin.Purple sweet potato,as a special variety of sweet potato,is a new sweet potato variety cultivated in Japan in the 1990 s.It has been widely studied and applied.In this paper,purple sweet potato is taken as the research object.Purple sweet potato polysaccharide is obtained by extraction and purification.The structure of the sweet potato is analyzed comprehensively.The inhibitory effect on the proliferation of different tumor cells is initially investigated,which provides a powerful method for further exploring the relationship between structure and biological activity.in accordance with.The extraction conditions of purple sweet potato crude polysaccharide are as follows: liquid-material ratio is 20: 1,extraction temperature is 80 ° C,extraction time is 2 hours,extraction times is 1 time,and alcohol concentration is 75%.Under these extraction conditions,purple sweet potato crude polysaccharide is obtained,and the extraction rate is: It was 6.1% and the polysaccharide content was 45.61%.Purple sweet potato crude polysaccharide was further deproteinized by Sevag method and diatomite adsorption method was used to remove pigment,and purple sweet potato polysaccharide(PSPP)with a sugar content of 69.12% was obtained.PSPP was purified by cellulose DEAE-52 chromatography column to obtain two kinds of polysaccharides(PSPP-?,PSSP-?).In this paper,PSPP-?,a component with a higher yield,was used for purification on a Sephacryl S-300 column to obtain a purple sweet potato polysaccharide(PSPP-?a)with a polysaccharide content of 97.65%.In this paper,the physical and chemical properties and primary structure of PSPP-?a were identified.Through a series of chemical coloration experiments and GPC,PSPP-?a was identified as a homogeneous polysaccharide.IR,Raman,HPLC,methylation,GC-MS and NMR The analysis showed that the molecular weight of purple sweet potato polysaccharide PSPP-?a was 15,000 Da,which contained ?-glycosidic bonds,and the sugar chains were connected in the manner of [Glcp(1 ?],[? 4)Glcp(1 ?],and a small amount of [? 4,6)Galp.(1 ?],the molar ratio is 0.4: 1: 0.12.On this basis,DSC-TGA was further used to analyze the purple sweet potato polysaccharide PSPP-? a by the thermodynamic characteristics,Congo red experiment,circular dichroism,XRD,particle size and potential analysis experiments.The higher-order structure of ?a was analyzed,and it was found that the polysaccharide had good stability at 200 ?,only 6.1% of the weight loss caused by the evaporation of crystal water between 30-90 ?;the space spiral structure of PSPP-?a did not have a triple helix The structure may be a single / double-stranded helical structure,and exists in an amorphous form;the purple sweet potato polysaccharide PSPP-Ia has a dispersion coefficient(PDI)value of 0.47,and the average particle size(Z-Ave)of the PSPP-Ia is 230.2 nm.And the distribution is relatively uniform,the composition is single.PSPS-The apparent morphology of a was observed,and it was found that under the scanning electron microscope,the observation was mainly irregular flake,columnar and elliptical structures.Under the high magnification observation,the polysaccharide surface was slightly uneven,and the center of some spherical structures was penetrated.Pore,the formation of some spherical structures is related to its amylopectin content;under the atomic force microscope,it was observed that the polysaccharide chain was a flexible winding chain and had irregular ring-shaped and network structures.The MTT method was used to detect the inhibitory effect of purple sweet potato polysaccharides on the proliferation of LOVO,HepG2,MCF-7,SCG-7901 and HCG-27.The growth of cell LOVO and breast cancer cell MCF-7 cells produced inhibitory effects,with inhibition rates of 46.7%,40.6%,and 34.9%,respectively,and had no inhibitory effect on the growth of gastric cancer cells SCG-7901 and gastric cancer cells HCG-27 cells.