Primary Structural Characterization And Biological Activity Study Of Sulfated Apple Pomace Polysaccharides

Apple pomace is a by-product of apple deep processing,and rich in dietary fiber.Squeezing can improve the proportion of water-soluble polysaccharides in dietary fiber.In this study,the soluble polysaccharide was extracted from apple pomace and sulfated modification to improve its bioactivity.The results will have great significance to improve apple comprehensive utilization value.In this study,the apple pomace was modified through squeezing and the water-soluble polysaccharide(APP)was extracted.Firstly,the polysaccharide was sulfated by aminosulfonic acid-N,N-dimethylformamide method,and the modified polysaccharides were purified by DEAE-52 cellulose column chromatography.Secondly,the micro-morphologic and chemical structure of polysaccharides were determined before and after sulfated.Finally,the physiological activity of the three tumor cells(RKO,MDA-MB-231 and HepG2)was evaluated by the in vitro antioxidant activity and the relationship between the chemical structure and the physiological activity.The main findings were as follows:1.APP was modified by aminosulfonic acid to obtain sulfated apple polysaccharide(SAPP)with a degree of substitution of 0.92.SAPP-1,SAPP-2 and SAPP-3 were obtained after purification.The degree of substitution was 0.19,0.63 and 0.97 respectively.2.From the UV and IR spectra,SAPP,SAPP-1,SAPP-2 and SAPP-3 all have characteristic absorption peaks after sulfation.Monosaccharide compisition analysis found that All the five kinds of polysaccharides contain rhamnose,fucose,Arabia suger,xylose,mannose,glucose and galactose.The molecular weights of APP,SAPP,SAPP-1,SAPP-2,SAPP-3 were be found to be 61.9,68.2,65.5,67.0 and 51.4kDa,respectively.By periodate oxidation experiment showed that five kinds of polysccharides have 1?6 glycosidic bond,also the 1?2 or 1?4 glycosidic bond.From the NMR,sulfate binging sites were in the C-6 and C-2 positions after sulfated modification.The scanning electron microscopy showed that the unprocessed APP particles were large,the sheet structure was dense,the surface was flat.The SAPP and the purified components were smaller,the morphology was different,the surface was rough and the surface area increased.3.The determination of reducing power showed that sulfated modification can improve the reducibility of polysaccharide significantly,and the reduction ability of SAPDF-3 of high degree of substitution is stronger.concentration of SAPDF-3 is 2.5 mg/mL,the Vc equivalent is 214.4 ?g/mL.Compared with the sulfated before(46.5?g/mL),the Vc equivalent has increased 4.6 times;antioxidant analysis results indicated that the degree of substitution greater the SAPDF-3 also has higher radical scavenging,when the concentration is 2.5mg/mL,DPPH free radical scavenging rate was 77.1%,superoxide anion radical scavenging rate of 62.4%,hydroxy radical scavenging rate was 67.9%,ABTS+? free radical scavenging rate of 75.4%.4.Anti-tumor test results showed a certain extent inhibitory action on the tumor cells of RKO,MDA-MB-231 and HepG2 respectively before and after sulfation,and HepG2 cells were more sensitive.The sulfated polysaccharide,compared with the polysaccharide,has increased the inhibition ratio of three kinds of tumor cells respectively,but acted weakly overall.The inhibitory rate of the three tumor cells was 34.59%(SAPP-3),32.16%(SAPP-2)and 38.59%.On value-added inhibition rate determination of human normal cells HL7702 showed that the five polysaccharides did not produce side effects on human normal cells HL7702 before and after sulphate modification.