Study On Extraction,purification And Antioxidant Activity Of Wheat Germ Polysaccharides

Active polysaccharides, a very important active substance in living creature or plants,are widely distributed in the world and can be obtained from plants,animals,microorganisms and so on.Because of its diversified biological activity, wide range of pharmacological effects,and low-toxic effects,more and more attention has been focused on its study and exploitation.Wheat germ has a various effects on healthcare and disease treatments,but few studies on the polysaccharides of wheat germ are reported.In this paper,wheat germ was employed for wheat germ polysaccharide (WGP) extraction,purification.In addition,the molecular weight of WGP was determined and its antioxidant activity in vitro was studied, which is helpful for the exploitation of WGP.The main conclusions are as follows:The best extraction conditions of WGP were studied.In the process of ultrasound-assisted extraction , with the indicator of extraction rate of polysaccharides,four-factor orthogonal experiment was designed on the bases of the single factor experiment.The optimum conditions were as follows: the solid to liquid ratio was 1:20,ultrasonic time was 5 min,extraction time was 180min, ultrasonic power was 80w,and the maximum extraction rate of polysaccharides from wheat germ was 18.06%;in the process of ethanol precipitation,with the indicator of ethanol condensate value,three-factor orthogonal experiment was designed.In view of ethanol condensate value and dosage of ethanol,the optimum conditions were that: dosage of ethanol was one volume, the time was 16h.The effect of TCA method on the removal of protein in wheat germ polysaccharide.TCA method was used in the removal of protein,with the indicator of protein removal rate and loss rate of polysaccharide,four-factor orthogonal experiment was designed on the bases of the single factor experiment.The optimum conditions were as follows:TCA concentration was 4%, reaction temperature was 80℃,reaction time was 60 min,amount of TCA was 15ml. At present,protein removal rate and loss rate of polysaccharide was 67.52% and 15.31%,respectively.WGP had strong antioxidant activity in vivo.Antioxidant activity of different concentrations of WGP in vitro was determined by DPPH free radicals,hydroxyl radicals,superoxide radical.The results showed that polysaccharides can remove DPPH free radicals,hydroxyl radicals and superoxide radical,meanwhile,removal ratio grow with the concentration of polysaccharide.Two polysaccharide components were obtained through the column chromatography.The separation was done on SephadexG-100 gel column,eluting with distilled water,determined by phenol-sulfuric acid method in detecting polysaccharides in 490nm absorb light value,draw elution curves;Collect the single-peak corresponding tube,after the freeze-drying get two polysaccharide components WGP I and WGPⅡ;UV,IR and HPLC were used to preliminary analysis WGPⅠand WGPⅡ,we found both two polysaccharide were free of protein and nucleic acid polysaccharide,molecular weight were 4381Da and 778Da respectively,WGPⅠcontains xylose and galactose,WGPⅡcontains glucose and galactose.