| Hizikia fusiforme is a solt of brown algae plant in ocean. It growns in the west area of north Pacific Ocean and our coastal. There are two activity polysaccharides-alginic acid and fucoidan in Hizikia fusiforme.The content and structure of alginic acid in Hizikia fisiforme is defferent from the alginic acid in else brown algae. Alginic acid is drown from Hizikia fusiforme in heat water and is precipitated in alcohol. Alginic acid is 16% in Hizikia fusiforme . Rough alginic acid is purificated by DEAE, and 8g comparative pure alginic acid is obtained from rough alginic acid. Outcome is 50%. The 8g comparative pure alginic acid is refine by cation exchange resin. Outcome is 71.88%(5.75g). Molecular weight of alginic acid is determinated by the method of characteristic viscosity and molecular weight is 16286Da. D--Manaronic acid(M) and L-gulonic acid(G) in the alginic acid is determinated, and M/G is 2.75. Fucoidan, a mixture of sulfated fucose-containing polysacchrides, have unique molecular structures and biological activities. Now the relationships between the structures and theactivities of fucoidan are studied widely. Fucoidans were extracted from brown seaweed Sargassum fusiforme which was cultured in the coast of Dongtou of Zhejiang province, and separated by anion-exchange chromatography on Q-Sepharose FF into three fractions: F-1, F-2 and F-3. F-2 was more homogeneous and abounded in both fucose residues and sulfated esters. We chose F-2 for the further structural studies corresponding to the analysis of their chemical compositions and average molecular weight. Analysis methods of anion-exchange chromatography, HPSEC, TLC, IR, acid hydrolysis, methylation reaction (GC-MS) and NMR are used.The average molecular weight of F-2 was estimated at 160,000, examined by HPSEC. The IR spectrum displayed that disulfated fucose existed in F-2. F-2 and its desulfated derivative F-2d are subjected to methylation analysis by GC-MS. It shows that (1→3)-linkage was major linkage pattern in fucose residues and (1→6)-linkage was major linkage pattern in galactose residues. Sulfate groups are substituted mainly at C-4 positions and secondarily at C-2 of fucose residues, some of the fucose residues were disulfated at C-2,4 positions. After hydrolysed and ultrafiltered (Mw5000 cutoff), F-2 was applied to gelchromatography Bio-gel P4, three hydrolitic products were obtained: F-2-a, F-2-b and F-2-c. By comparing their chemical compositions and average molecular weight with F-2, we deduce that F-2 contains main chains composed mainly of fucose, galactose, mannose and gluctose, and a considerable amount of galactofucan side chains (F-2-c) with about 6~8units. Sulfation occurs at both main and side chains. The NMR analysis of oligosaccharide F-2-c was consistent with the methylation analysis, including the mainly linkage pattern and substituted positions. But (1→3)-linkage was major linkage pattern of β-galactose residues in the side chains of F-2. A major structure modle of F-2-c is put up.Biological activity of the alginic acid from sargssum fuciforme is studied.There are obvious results in regulating the blood fat of animal model. Cholesteral (TC), glycerin trilaurate(TG) and low density lipoprotein(LDL) are cut down and high density lipoprotein(HDL) is raised(P≤0.01). Blood sugar of high blood sugar animals and sick persons, and the sugar tolerance is improved(P ≤0.01).The alginic acid can impromote growth and development of experimental animals(rat,P≤0.01).
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