Study On The Extraction,Purification And In Vitro Simulated Digestion Of Polysaccharides From The Umbilicaria Of Huangshan

Umbilicaria is a lichen plant with the symbiosis of fungi and algae.It contains high protein and many types of microelement and has high edible and medicinal value.The polysaccharide can also be separated from the Umbilicaria.It is mainly composed of mannose,glucose,and xylose,etc.The structure of polysaccharide is stable,and it has biological activity performance,such as antioxidant activity,lipid-lowering and anticancer activity,etc.At present,the research about polysaccharides of Umbilicaria mainly focuses on the optimization of water extraction process and the identification of structural properties.However,there are few researches on the simulated digestion of polysaccharides from Umbilicaria.In this research,firstly,the polysaccharide was extracted based on microwave method,and then purified by macroporous resin.Finally,the in vitro digestion model was established to explore the process of polysaccharide digestion,and the biological activity with different periods of digestion was investigated.Firstly,the microwave extraction technology of polysaccharides from Umbilicaria was discussed.Taking the extraction rate of polysaccharides from Umbilicaria as the reference index,the effects of microwave time、microwave power、material liquid ratio and extraction times on the extraction rate were explored respectively.Moreover,the central point was determined by a single factor experiment.Finally,the extraction process was optimized by response surface analysis.When the microwave time of 360s,microwave power of 350w,material liquid ratio of 1:30 g/mL and the times of extraction was once,the extraction rate of polysaccharides was 20.14%.Secondly,the macroporous resin was used to enrich and purify the polysaccharide.AB-8 macroporous resin was selected as the suitable resin type by static experiment.Through the adsorption orthogonal experiment,it was determined that the concentration of the sample solution was 2.0mg/mL,the sample speed was 0.4BV/h,and the sample volume was 0.5BV.At the moment,the adsorption rate of the polysaccharide was 88.23%.Through the orthogonal experiment of desorption,we can discover that the best desorption condition was the concentration of 100%ethanol solution,the elution speed 0.5BV/h,and the elution volume 1.5BV.At this time,the desorption rate of polysaccharides was 97.84%.Finally,the content of polysaccharides was 67.9%,which was 12.3%higher than that of polysaccharides extracted by microwave.Then the enriched,separated and purified polysaccharide was separated by the DEAE-cellulos-52 column,and two purified components were obtained,named UPS-1 and UPS-2 respectively.After that,in vitro digestion profiles of UPS-1 and UPS-2 in saliva,gastric and small intestinal digestion system were investigated.The results showed that the molecular weight of the two components did not change significantly and no new monosaccharide was produced with the increase of digestion time in the process of simulating the digestion of saliva,gastric juice,and gastrointestinal juice.At the same time,there was no effect on the total sugar content and reducing sugar content of UPS-1 and UPS-2,which demonstrated that it is hard for the polysaccharide of Umbilicaria to be digested in the mouth,stomach and small intestine and was not easy to degrade.The molecular weight of two components of Umbilicaria polysaccharides was determined by high performance gel chromatography.It was found that their purity was high.The monosaccharide composition was determined by PMP pre column derivatization.It was found that UPS-1 was mainly composed of glucose and a small amount of mannose,and UPS-2 was mainly composed of mannose.Finally,the activities of UPS-1 and UPS-2 in different times of digestion of simulated saliva,gastric juice,and gastrointestinal juice were measured.The antioxidant activities of UPS-1 and UPS-2 were studied before and after digestion by chemical method,and the hypoglycemic and hypolipidemic activities of UPS-1 and UPS-2 before and after digestion were explored by chemical method.The results showed that UPS-1 and UPS-2 before and after digestion showed good antioxidant activity,hypoglycemic and hypolipidemic activity.In the process of salivary digestion,the α-amylase inhibitory activities of UPS-1 and UPS-2 were inhibited slightly.After digestion of gastric juice and gastrointestinal juice,the ability of UPS-1 and UPS-2 to scavenge ABTS free radical,DPPH free radical and hydroxyl free radical increased to some extent,and the pancreatic lipase inhibitory activity decreased marginally.