Extraction, Isolation, Structural Characterization And Bioactivities Of Polysaccharides From Green Algae Wild And Low Salinity Cultured Chaetomorpha Linum

In this paper, the green algae wild and low salinity cultured Chaetomorpha linumwere used for the study, the algae were firstly delipided with85%ethanol, thenextracted with room temperature water,85℃hot water and5%sodium bicarbonatewater solution at85℃, five types of crude polysaccharides which named as CLCa,CLHa, CLAa, CLCband CLHb，were required. The yields of CLCa, CLHa, CLAa,CLCband CLHbwere2.3%,14.3%,3.1%,3.2%and26.3%. Their Charge density，relative molecular weight (Mw)，monosaccharide composition, and structural featureswere determined with Cellulose acetate electrophoresis(CAME)，high performancegel permeation chromatography-multi angle laser light scattering (HPGPC-MALLS)，high-performance liquid chromatography (HPLC) and Fourier transform infraredspectroscopy(IR), respectively. The results showed that CLCa, CLHa, CLAa, CLCband CLHbsulfate contents were11.4%,13.0%,9.4%，9.8%and11.3%; their molecularmass were129.5kDa,602.3kDa,417.4kDa，62.85kDa and484.2kDa, respectively.The purity of the polysaccharides CLHaand CLHbextracted from hot water washigher. The HPLC analysis data showed all polysaccharides were mainly composed ofglucose, galactose and arabinose, and the percentage aera were29.4:30.9:28.9,3.7:21.0:67.2,6.2:33.4:57.2,56.1:33.4:8.3and16.0:19.9:57.3, respectively. Inconclusion，the wild and low salinity cultured Chaetomorpha linum polysaccharideswere sulfated arabinogalactan. The sulfate content and molecular weight inpolysaccharide of cultured Chaetomorpha linum were lower, but the glucose contentwas higher than that of wild type, indicated lowering salinity could not only reducethe molecular weight and sulfate content, but also change the monosaccharidecontent. Based on the physicochemical analysis of CLHaand CLHb, twelfth kinds ofpolysaccharides CLHa1~6and CLHb1~6were respectively separated from CLHaandCLHbby using Q-Sepharose Fast Flow anion-exchange chromatography. Twelfthkinds of polysaccharides were analyzed that molecular weight and sulfate contentwere115~528kDa and9.4~13.8%, respectively; monosaccharide composition ofevery components was arabinose and galactose. The results HPGPC and celluloseacetate electrophoresis showed the purity of CLHa5was higher, molecular weight was170kDa, and sulfate content was13.8%，CLHa5was mainly composed of galactose(19.8%) and arabinose (71%). Based on the methylation analysis of CLHa5andDSCLHa5and NMR spectroscopy, CLHa5was a highly branched polysaccharide. Thebackbone of CLHa5were-(1�'4)-D-Galp、-(1�'4,6)-D-Galp、β-(1�'3,4)-L-Arap;the branches were β-(1�'4)-L-Arapand β-(1�'4)-L-Arap2S, the end of branch wasXylpand Araf.In order to study the fine structure, CLHa5was selected for oligosaccharidespreparation, the degradable optimum conditions was0.2M HCL,80℃,1.5h. UsingBio-Gel P4to purify oligosaccharide mixture, a series of A9S8, A8S7, A7S7etc whichwere different polymerizations and sulfation of oligosaccharides were gained. Thenumber of polymerized degrees and sulfate groups of oligosaccharides weredetermined by ESI-MS, the next bioactive experiment was based on highly sulfatedarabinose oligosaccharides.Glucosidase inhibitory, anticoagulant and antioxidative activities ofpolysaccharides and oligosaccharides were evaluated. The results showed the lowsalinity cultured Chaetomorpha linum polysaccharides CLHband CLHowhich wasmodified by chemical methods has good-glucosidase inhibitory activity, but theanticoagulant and antioxidant activity of Chaetomorpha linum polysaccharides weremuch lower than the positive control.