Extraction,Isolation Purification And Properties Of Polysaccharide Of Selenium-enriched Dark Tea

Selenium Polysaccharide,an organic selenium compound with dual activities of selenium and polysaccharides,has become a new research hotspot due to its high bioavailability and low toxicity.It has many activities such as anti-oxidation,anti-tumor and immune immunity.The selenium-enriched tea polysaccharide is a selenium polysaccharide extracted from selenium-enriched dark tea,which has a good application prospect,but there are few reports on it at home and abroad.In this thesis,the selenium-enriched dark tea polysaccharide was extracted from the selenium-enriched dark tea in Hubei Province,and the physicochemical properties and in vitro activities of the selenium-enriched dark tea polysaccharide were studied.The main findings are as follows:(1)By analyzing the basic components of selenium-enriched dark tea raw materials,the selenium content of selenium-enriched dark tea meets the national standard for selenium-enriched tea.The single factor experiment of polysaccharide extraction from selenium-enriched dark tea showed that the extraction temperature was 90 °C,the extraction time was 2 hours,and the ratio of extract to liquid was 1:20.The response surface design software designed and optimized the extraction process of selenium-enriched dark tea polysaccharide.The optimum extraction temperature was94.2 ?,the optimum extraction time was 1.64 hours,and the optimum extraction ratio was 1:20.56.Because the response surface analysis shows that the extraction time and the ratio of the extraction liquid to the polysaccharide yield are extremely significant,the effect of the extraction temperature on the yield of the polysaccharide is significant.Finally,the extraction temperature is 95 ? for the extraction,and the extraction time is In 2 hours,the ratio of material to liquid extracted was 1:20.The polysaccharide yield was about 6% under such extraction conditions.Selenium-enriched dark tea polysaccharide was separated by DEAE Sepharose Fast Flow to obtain six different components,and finally the absorbance was measured at490 nm.Collect different components separately.The acid sugar assay of each component eluted and separated showed that the six components eluted were high in uronic acid content and were typical acidic polysaccharides.(2)By ultraviolet full-wavelength scanning of the crude selenium-enriched dark tea polysaccharide and several separated eluting components,the crude selenium-enriched dark tea polysaccharide and the separated and eluted componentshave no absorption peak at 280 nm,indicating that selenium-enriched dark tea polysaccharide none of them contain aromatic amino acids.Polyacrylamide gel electrophoresis showed that the crude selenium-enriched dark tea polysaccharide and the separated eluting components did not contain free protein.Infrared spectroscopy revealed that the selenium-enriched dark tea polysaccharide and the separated and eluted components all contained a distinct sugar structure.Gel reverse osmosis chromatography knows that the selenium-enriched dark tea polysaccharide has a relatively large molecular weight and contains an amide bond.It is preliminarily concluded that they are a combination of sugar and protein.Ion Chromatography knows that selenium-enriched dark tea polysaccharide contains 11 monosaccharides.From the results of scanning electron microscopy and atomic force microscopy,it is known that the segregation and elution components of selenium-enriched dark tea polysaccharides differ in their apparent structure,and their surface flatness is also greatly different.From the XRD diffraction pattern,it is known that the selenium-enriched dark tea polysaccharide and the eluted fraction have different crystal formation.Thermal characteristics and data show that there is also a difference between the segregation and elution components of selenium-enriched dark tea polysaccharides.(3)ABTS free radicals clear experiments show that the selenium-enriched dark tea polysaccharide has no obvious clear activity on ABTS free radicals but there are differences between the components.Clear experiments of superoxide anion radicals showed that the selenium-enriched dark tea polysaccharide had no obvious clear scavenging activity on superoxide anion radicals and there was no difference between the components.The ?-glucosidase inhibition assay knew that both the selenium-enriched dark tea polysaccharide and the eluted fraction had inhibitory activity against ?-glucosidase and was significant compared with the positive control acarbose.The in vitro digestion experiment of artificial gastric juice knows that the extracted selenium-enriched dark tea polysaccharide is not pure,and also contains other substances such as protein and polyphenol.Through the in vitro digestion experiment of artificial semen liquid on the selenium-enriched dark tea polysaccharide and the separated elution components,it is known that the extracted selenium-enriched dark tea polysaccharide is not pure,and contains other substances such as protein and polyphenol.(4)By further separating and purifying the component 4,a uniform component wasobtained,and a superoxide anion radical and an ABTS radical scavenging experiment were performed on the uniform component.The scavenging activity of free radicals was positively correlated with the concentration of homogeneous components,and the ABTS free radical scavenging rate reached 80% and the superoxide anion free radicals reached 70% at a concentration of 1 mg/ml.