| Costaria costata. Saccarina japonica, Kjellmaniella crassifolia are three brown algaewith high economic value. Fucoidan is a kind of heteropolysaccharides containingsulfate group, found in brown seaweeds and some echinoderms. Fucoidan showsvarious biological activities, which gradually become a reseach hotspot of the marinebioactive ingredients. In this article,4,3and4fucoidan fractions were obtained byDEAE-Sepharose Fast Flow anion-exchange chromatography purification from threebrown algae respectively. The contents of total saccharide, SO42-, and fucoidan ofeach fraction were determined, molecular structures of each fraction were also studied.The results and conclusions are as follows:Fucoidan was extracted from Costaria costata. Saccarina japonica, Kjellmaniellacrassifolia by enzymatic method, named as CF, SF, KF respectively, and then purifiedby anion-exchange chromatography on DEAE-Sepharose Fast Flow. Four fractions,CF1, CF2, CF3and CF4were obtained from Costaria costata and the yields were2.81%,27.55%,11.44%and23.48%respectively. CF2was a fraction with low SO42-content(1.01%), and CF4was high with SO42-content(16.12%). Three fractions, SF1,SF2and SF3were obtained from Saccarina japonica and the yields were12.95%、63.71%and15.70%respectively. SF2was a fraction with low SO42-content(5.56%),and SF3was high with SO42-content(27.08%). Four fractions, KF1, KF2, KF3andKF4were obtained from Kjellmaniella crassifolia and the yields were4.41%,18.98%,4.04%and57.45%respectively. KF1was a fraction with low SO42-content(4.27%), and KF4was high with SO42-content(29.31%).The fractions from Saccarina japonica and Kjellmaniella crassifolia are pure, therelative molecular weights were estimated to be48KD for CF1,146KD for CF2,155KD for CF3,136KD for CF4,136KD for SF1,119KD for SF2and104KD forSF3by Sephadex G-200chromatography. The third fraction from Costaria costata bySephadex G-200chromatography has two compositions, namely CF3-1and CF3-2,which show that the fractions CF3from Saccarina japonica is heterogeneous. Therelative molecular weights were estimated to be103KD for CF3-1,5KD for CF3-2,52KD for CF1,5KD for CF2and94KD for CF4.IR spectrum, GC and NMR were apllied for studying Molecular structures of thefucoidan fractions from three brown algae. The findings of monosaccharidecomposition of these fractions by GC chromatography showed that, most fractions are heterogeneous, fucose, galactose and Mannose were the major monomers, xylose,and glucose were detected in smaller quantities. just like most of the brown algaes.The monosaccharide composition of fraction SF3and KF4is single, fucose is the onlymonosaccharide(100%). Among these fractions, the highest content of SO42-andfucose were CF4, SF3and KF4., respectively, and the contents of fucose were therelatively the highest compared with other fractions for the same brown seaweed, Theresults of IR spectrum indicated that absorption peaks of O-H（3450-3300cm-1）,C-H(2935cm﹣1) and S=O(1250cm﹣1) existed in each fraction, which demonstratedthat all fractions were fucoidans with sulfate substitute. The sites which sulfatedisplaced were determined by comparing absorption peaks of C-O-S(845cm﹣1and820cm﹣1), which revealed that SF3, KF2, KF3and KF4were at Fuc C-4，CF1, CF2,CF3and SF2at Fuc C-2, C-3and Gal C-6, CF4, SF1, KF1at Fuc C-2, C-3, C-4andGal C-4, C-6. The configuration of glycoside bond of CF2, SF2is presumablyβ-D-pyranose by the absorption peak at880cm-1,and CF4, SF1, SF3, KF1, KF2, KF3and KF4is presumably α-pyranose by the absorption peak at850cm-1. The results ofNMR as follows:1H NMR spectrum revealed that methyl presented at highfield(1.2ppm), and no anino sugar probably;13C NMR spectrum indicated that100-105ppm is the displacement of C1,69－73ppm is the displacement of C2-C5,17-18ppm is the displacement of C6,74－83ppm is the displacement of sulfated. |
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