The Separation,Purification And Structure Characterization Of Polysaccharides From Umbilicaria Tornata On Taibai Mountain

Due to prominent biological activity,complex chemical structure and low toxic and side effects,polysaccharides have been the focus of biochemistry and medicine field.Meanwhile,polysaccharide is also one of the quality control indexes of medicinal materials.The in-depth study of the structure and activity of polysaccharides can provide reference for the quality control of medicinal materials.Heishier is one of the medicinal lichens on Taibai Mountain.The sources of Heishier are Umbilicaria tornata?Ach.?Del or Dermatocarpon miniatum?L.?Mann.The two kinds of active ingredients in the U.tornata are lichen acids and polysaccharides,and the lichen polysaccharide is the main component of U.tornata decoction,so this thesis takes the U.tornata as the research object.We conducted the extraction,purification,structure identification and in vitro activity tests,to compare structure and antioxidant activity of the polysaccharides of the two kinds,to analysis the similarities and differences of the two kinds of experimental data,to provide quality control reference of Heishier.The results are as follows:1.The ultrasonic assisted extraction technologies of polysaccharides from U.tornata and D miniatum were optimized.Under the optimal conditions,the yield of UTP was 5.19%,the carbohydrate content of UTP was 79.33%,the protein content of UTP was 2.16%;the yield of DMP was 5.88%,the carbohydrate content of DMP was 80.71%,the protein content of DMP was 0.63%.2.The UTP and DMP were preliminarily purified by DEAE-52 cellulose column,and obtained three UTP isolated fractions?UTP1,UTP2 and UTP3?and four DMP isolated fractions?DMP1,DMP2,DMP3 and DMP4?.The carbohydrate contents of UTP2 and DMP2,containing higher carbohydrate content and easier to collection fractions,were 88.29%and90.63%.The UTP2 and DMP2 were further purified by Sephadex G-200 column,and obtained two UTP2 isolated fractions?UTP2-A and UTP2-B?and two DMP2 isolated fractions?DMP2-A and DMP2-B?.The carbohydrate contents of UTP2-A and DMP2-A,containing higher carbohydrate content and easier to collection fractions,were 92.74%and94.55%.3.The physicochemical properties of UTP2-A and DMP2-A were studied by high performance gel chromatography,gas chromatography and infrared spectroscopy.The structures of UTP2-A and DMP2-A were analyzed by methylation and NMR analysis.The physicochemical properties showed that the UTP2-A is composed of glucose and mannose,in the molar ratio of 16.49:1.00 with molecular weight of 36594 Da;the DMP2-A is composed of glucose,mannose and xylose,in the molar ratio of 21.75:1:2 with molecular weight of67538 Da.The methylation and NMR analysis results showed that UTP2-A was dextran with a skeleton structure of?1?6?-?-D-Glcp and DMP2-A was dextran with a skeleton structure of?1?3?-?1?6?-?-D-Glcp.4.The antioxidant activities in vitro of UTPs and DMPs were studied by four screening systems.The results showed that the antioxidant activities of tested samples of different test systems were different.The all samples displayed the strongest activities in the ferrous ion chelating system,and the IC₅₀0 of UTP2 and DMP3 on ferrous ion chelating activity was 0.293mg/mL and 0.522 mg/mL.UTP2 and DMP2 exhibited potential ability to be developed as natural antioxidants due to their generally stronger antioxidant activities in vitro.