Extraction, Isolation，Purification，Structural Analysis Of The Polysaccharide From Dendrobium Candidum

Dendrobium candidum Wall.ex Lindl is a perennial epiphyticherb.It mainly distributes in the northwester Guangxi, southwester Anhui,eastern Zhejiang Province, western Fujian, Sichuan, southeast Yunnan.Dendrobium candidum as a valuable Chinese herb has lots ofpharmacology effect, such as benefit stomach, nourish yin clear heat,embellish lung cough, smooth larynx bright eye, prolong life effect.Extraction, isolation, purification, structural analysis and antio-xidant activities of the polysaccharide from Dendrobium candidum werestudied in this dissertation. The following portions were included in thedissertation.1. Extraction,isolation and purification of the polysaccharide fromDendrobium candidum.The crude polysaccharide of Dendrobium candidum was extractedby hot water,protein was removed by enzyme and Savage method.Polysaccharide DOP1、DOP2were purified by sephadex G-75column.The purity of polysaccharide DOP1、DOP2were tested by celluloseacetate membrane electrophoresis and gel column chromatographyrespectively.The experiment showed polysaccharide DOP1was pure and Polysaccharide DOP2was mixed.2. The structure analysis of the polysaccharide from DendrobiumcandidumThe viscosity average molar mass of polysaccharide DOP1wasestimated to be3.78×104by viscometry.The acid-hydrolyzed polysacch-aride DOP1was determined by high pressure liquid chromatography,thepolysaccharide DOP1was composed of mannose,rehamnose,glucose,galactose,arabinose and the ratio is2.221∶1.375∶2.010∶2.322∶1.The structure of polysaccharide DOP1were1→6bonding inferred on IR,1HNMR,13CNMR,periodate oxidation and Smith degradation.3. Antioxidant activities of polysaccharide DOP1, polysaccharide DOP2The result of antioxidant activities indicated superoxide radicaland hydroxyl free were eliminated by polysaccharide DOP1and DOP2invitro.The activities depended on their amounts.