The Isolation And Structural Elucidation Of Several Bioactive Polysaccharides

Carbohydrate polymers are one of important biomacromolecules. In organisms, besides being the resources of energy and materials of cell structure, the saccharides contain a lot of biological information, and function as one of the communication carriers. Therefore, investigation on saccharides is of great significance for disclosing the essence of life.This dissertation was divided into three parts as following:Part I:the polysaccharide was extracted from Hyriopsis cumingii, and systematically studied:1) A water-soluble polysaccharide from H. cumingii (HCp) was isolated by hot-water extraction and ethanol precipitation. HCp was purified and fractioned through fast-flow DEAE-Sepharose and Sephadex G-200 chromatography to afford its major component, HP-I. On the basis of composition analysis, PC, methylation analysis, acetolysis, infrared spectra (IR) and nuclear magnetic resonance (NMR) experiments, the structure of HP-I is identified, an a-D-glucan branched with a single a-D-glucose at C-6 every five residues on average.2) The preliminary neuroprotective activity of HCp was investigated on cerebral ischemia/reperfusion (I/R)-induced rat brain tissue injury by using the middle cerebral artery occlusion (MCAO) model. Pharmacological studies revealed that HCp can improve and restore nerve function impairment, significantly increase brain tissue total superoxide dismutase activity, lower malondialdehyde content effectively, and reduce brain levels of caspase-3 mRNA expression in a dose-effect manner, indicating that H. cumingii polysaccharide possesses significant neuroprotective effects.Part II:The polysaccharides from Eremurus anisopterus (Ker. et Kir) Regel roots were studied. The polysaccharides were isolated by water extraction and ethanol precipitation. After decoloured, the polysaccharides were purified and fractioned through fast-flow DEAE-Sepharose and Sephadex G-200 chromatography to afford the major component, E1. On the basis of composition analysis, methylation analysis, periodate oxidation analysis, Smith degradation, infrared spectra (IR) and nuclear magnetic resonance (NMR) experiments, El is a novel linear galactomannan with a main chain composed of (1→6)-linkedα-D-Galp and (1→2)-α-D-Manp at a relative molar ratio of 1:3.PartⅢ:the polysaccharides from Rubus parvifolius were extracted and isolated primarily. The water-extractable and the alkali-exactable polysaccharides were extracted by hot water and then KOH solution. The water-extractable polysaccharides were purified and fractioned through fast-flow DEAE-Sepharose and Sephadex G-200 chromatography to obtain the major component, MD11, and its molecular weight was determined by HPGPC. The structure elucidation is going on.In addition, the current state and development of research on polysaccharide and the difficulties we faces are simply reviewed.