Extraction, Isolation And Structural Characterization Of Polysace-harides From Rabdosia Rubescens

In this dissertation, research of extraction, isolation, purification, physicochemical properties, homogeneity and structure of Rabdosia rubescens polysaccharid were made. A series of assay of antioxidant activity in vivo was also carried among four Rabdosia rubescens polysaccharid with different molecular weight. The main contents and conclusions are listed as follows:1. The extraction process of Rabdosia rubescens polysaccharides was more systematic researched, such as the extraction conditions was determined(solid:liquid=1:10, extracted 6 h with 1%NaOH after extracted 6 h with hot water) through single-factor test. Method of isoelectric point was applied to removal of protein by studying, and physicochemical characteristics of RRPS were investigated.2. Compoents of polysaccharide (8) were obtained by a combination of ion exchange chromatography and gel permeation. Four kinds of polysaccharides STPS-Ⅱ-a. STPS-Ⅱ-b,JTPS-Ⅱ-a and JTPS-Ⅱ-b were proved with higher purities by HPLC, their molecular weights were estimated as 39.1 kD,19.8 kD.26.2 kD,13.7 kD, respectively. The sugar contents of them were 70.5%,70.3%,85.1%,82.3%. Uronic acid contents of them were 10.5%,12.3%,9.8%,8.3%, respectively. Protein contents of them were5.5%,4.7%,4.3%,4.5%, respectively. STPS-Ⅱ-a and STPS-Ⅱ-b was mainly composed of Gal, Man, GalUA and Ara, while JTPS-Ⅱ-a and JTPS-Ⅱ-b mainly composed of Xyl, Ara, Gal and GalUA by PMP-HPLC.3. The primary structure of JTPS-Ⅱ-a was elucidated by chemical methods and spectroscopic techniques, such as acid hydrolysis, IR, PMP-HPLC, GC-MS and NMR. Structural analysis showed that JTPS-Ⅱ-a was heteropolysaccharides with Xyl, Ara, GlcU A and Rha, and the main chain was mainly composed of Xyl, Ara and Rha. GlcUA was located in the fork chain, and the branch maybe at C-2 position of Rha.4. Antioxidant activity of STPS-Ⅱ-a,STPS-Ⅱ-b,JTPS-Ⅱ-a and JTPS-Ⅱ-b was investigated by various antioxidant assay in vitro systems, including DPPH radical scavenging, hydrogen radical scavenging, superoxide anion radical scavenging and inhibition against liposome peroxidation. The results indicated that STPS-Ⅱ-a and STPS-Ⅱ-b had significant ability on the scavenging of DPPH radical and hydrogen radical, while the ability of JTPS-Ⅱ-a nad JTPS-Ⅱ-b relatively weak. In addition, STPS-Ⅱ-a,STPS-Ⅱ-b,JTPS-Ⅱ-a and JTPS-Ⅱ-b all showed no ability on the scavenging of superoxide anion radical and inhibition against liposome peroxidation.