| Mulberry,the fruit of mulberry plant(Morus alba L.)belonging to mulberry family,has good flavor,high nutritional value and medicinal value.As one of the main active substances of mulberry,polysaccharides are widely welcomed.Mulberry polysaccharides possess a variety of biological activities and are favored by Chinese and foreign researchers due to their excellent antioxidant capacity.At present,studies on mulberry polysaccharides mainly focus on the structural characterization and physical and chemical properties of polysaccharides,but there is no research on mulberry polysaccharides in alleviating colitis,which is not conducive to the development of mulberry polysaccharides in the fields of new drugs and functional foods.In this study,different extraction methods and different particle sizes are used to assist in the extraction of mulberry polysaccharides.The optimal extraction method is determined by testing the rheological properties and antioxidant activity,and the extraction process is optimized.The basic components and structural characteristics of the purified mulberry polysaccharides are separated,analysis.Finally,the protective effect of polysaccharide from mulberry on intestinal tract in mice with ulcerative colitis model.The main conclusions are as follows:1.Hot water extraction,ultrasonic assisted extraction,enzyme assisted extraction,high speed shearing technique assisted extraction method are used,as well as 60 mesh,80 mesh,100 mesh are used to assist the extraction of mulberry polysaccharide.Among them,extraction rate of polysaccharides from 100 mesh polysaccharides from mulberry assisted by high speed shearing technique is the highest,which can reach(9.95 ± 0.19)%.The static rheological characteristics show that the apparent viscosity of enzyme-assisted extraction of polysaccharide solution is the highest,and the restorability and thixotropy property of polysaccharide solution are the best.The results of dynamic rheology show that the high speed shearing technique assisted extraction of polysaccharides has better elastic property,and the changes of particle sizes have little effect on the rheological property of mulberry solution.The antioxidant capacity of mulberry polysaccharides is determined,and the results show that all polysaccharides have antioxidant activity and reducing capacity to a certain extent,and present a concentration-dependent relationship.The antioxidant capacity is inversely proportional to the particle size,the smaller the particle size,the better the antioxidant capacity.High speed shear assisted extraction of mulberry polysaccharides over100 mesh has the highest scavenging rate of ABTS free radical,hydroxyl free radical andDPPH free radical,and the strongest reducing ability.The above experiments indicate that high speed shearing technique assisted extraction is beneficial to the further processing and utilization of polysaccharides from mulberry.2.The orthogonal analysis method is used to optimize the extraction process of polysaccharide from mulberry assisted by high speed shearing technique.Polysaccharides from mulberry are isolated and purified,and purified polysaccharide PMF is obtained.According to the determination of its basic components,the content of sugar,protein and uronic acid in PMF was 89.73%,2.3% and 6.7% respectively.To detemine the molecular weight of PMF,it is 96.17 k Da.The monosaccharide is studied with chromatography method,PMF is composed of glucose,arabinose,galacturonic acid,glucuronic acid,mannose,rhamnose,galactose,and fucose with a molar ratio of 33: 2.57: 1: 7.43: 8.57: 5.29: 5.57:7.43.3.The protective effect of polysaccharides of the mulberry on intestinal tract and the mechanism of alleviating inflammation are studied by dextra sulfate sodium-induced(DSS)ulcerative colitis mouse model.The results show that: PMF can improve the colitis caused by weight loss,fecal nonmolding and hematochezia;PMF can relieve colonic length shortening,bleeding,intestinal wall becoming brittle,spleen enlargement and other phenomena. |
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