Chemical Research On A Few Kinds Of Naturally Bioactive Polysaccharides

Protein,nucleic acid and polysaccharide(or oligosaccharide) were the mostimportant three biomacromolecules. In organism, the saccharides as resource ofenergy and materials of structure showed the potential of cell recognition, substancestransfer between cells, immune function and others. So in life system, the saccharideshave analogous importance compared with proteins and nucleic acids.The dissertation was divided into four parts as below.PartⅠ: in vitro and in vivo immunological activities and anti-lipid peroxidecapacity of various extracts including petroleum ether extract (PE), ethyl acetateextract (EAE), ethanol extract (EE) and glycoprotein (GP), and a purifiedpolysaccharide (PS) together with boiling water extracts (CGP and CWPs) from themycelia of Cordyceps sinensis were studied. The results of splenocyte proliferationassay in vitro showed that PE, EAE, EE, and GP significantly enhanced/inhibited theconcanavalin A (Con-A)-and lipopolysaccharide (LPS)-induced mice splenocyteproliferation at suitable doses. The results of PE, EAE, EE, GP and PS on thecellular and humoral immune responses of ovalbumin (OVA)-immunized miceshowed that PE, EAE, EE and GP significantly enhanced T splenocyte proliferationstimulated by Con A and B splenocyte proliferation stimulated by OVA, however, nosignificant differences were observed in the mice between PS/OVA group and OVAgroup. PE, EAE, EE, GP and PS significantly enhanced the serum OVA-specific IgG,IgG1 and IgG2b levels in mice immunized with OVA. The results of anti-lipidperoxide showed that CGP and CWPs have a definite inhibitory capacity in apositive dose-dependent manner. The inhibitory rate of CGP was higher than that ofCWPs at the same doses, however, their effects were both weaker than that ofVitamin C.PartⅡ: the polysaccharides from the mycelia of Cordyceps sinensis weresystematically studied. 1) The crude polysaccharides (CWPs) extracted with hotwater were fractionated and purified by a column of DEAE-Sepharose Fast flow to afford CS1. The structure was investigated using PC, GC, IR, hydrolysis studies,periodate oxidation and Smith degradation, NMR spectroscopy, and reaction withβ-D-glucanase, and the results indicated that CS1 consisted of a backbone composedof (1→3)-β-D-glucosyl residues and carried a single (1→4)-β-linked D-glucosylresidue. 2) Polysaccharides from C. sinensis mycelium, extracted with 0.05 M acetatebuffer successively, were fractionated and purified by an anion-exchange column ofDEAE-Sepharose Fast flow and a gel-filtration column of Sephadex G-100 to affordAA1. A combination of methylation analysis, periodate and chromium trioxideoxidation, Smith degradation, graded acid hydrolysis, NMR and IR spectroscopy, andreaction withα-D-amylase, it is found that AA1 possesses anα-(1→4)-(61.3%) andα-(1→3)-linked (28%)D-glucan backbone, and the singleα-D-mannopyranosyl groups(10.7%) as side-chains were attached to the backbone via O-6 of (1→3)-Glcp residues.3) The polysaccharides extracted with 0.05 M phosphate buffer from the mycelia ofCordyceps sinensis were fractionated and purified by an anion-exchange column ofDEAE-Cellulose-52 to afford CSP1. Methylation, Smith degradation, acetolysis,NMR spectroscopy and acid hydrolysis studies were conducted to elucidate itsstructure. The results indicated that CSP1 consisted of a backbone composed of(1→4)-D-glucosyl residues and carried a single (1→6)-linked D-glucosyl residue.PartⅢ: the acid polysaccharides from the seeds of Retama raetam ssp.gussonei in Libya were studied. After defatting, delignifying and extracting with hotwater, the residues were sequentially extracted with 3, 6 and 15% aqueous sodiumhydroxide to afford four crude polysaccharides. After decolorization, precipitationprocess of Fehling solution, dissociation of the complex with acetic acid, and isolationby repeated precipitation with ethanol, the RR1 was obtained. Its composition andlinkage determination had been investigated using component analysis, methylationanalysis, hydrolysis studies, and NMR spectroscopy analysis. This was shown toconsist of a backbone ofβ-(1→4)-linked D-xylopyranosyl residues, having branchesofα-D-glucopyranosyl residues which contained (1→2)-linkages, and 4-O-methyl-α-D-glucopyranosyluronic acid at O-2. The antioxidant experiments in vitro of neutraland acid crude polysaccharides indicated that they all have a significant inhibitory action on lipid peroxide.PartⅣ: the polysaccharides from the fruits of Ficus carica extracted with hotwater were studied. Crude polysaccharides (FCCP) were fractionated and purified byion-exchange and gel-filtration chromatography to afford sixteen moieties (FCA-FCP), the yield and hexose content of FCA-FCP were detected, and componentanalysis, distribution of molecular weights of FCA, FCB, FCE, FCG, FCJ, FCM,and FCN were studied. The activity test showed that the capacity of anti-lipidperoxide of FCCP was in a positive dose-dependent manner, and however, weakerthan that of Vitamin C.In addition, the current state of research and structure-activity relationship ofpolysaccharides was simply reviewed.