The in vitro antioxidant activities of the following six sulfated polysaccharides were investigated: iota, kappa and lambda carrageenans, which are widely used in the food industry, fucoidan (homofucan) from the edible seaweed Fucus vesiculosus and fucans (heterofucans) F0.5 and F1.1 from the seaweed Padina gymnospora. With respect to the inhibition of superoxide radical formation, fucoidan had an IC 50 (the half maximal inhibitory concentration) of 0.058 mg I mL j1 , while the IC 50 for the kappa, iota and lambda carrageenans were 0.112, 0.332 and 0.046 mg I mL j1 , respectively. All of the samples had an inhibitory effect on the formation of hydroxyl radicals. The results of peroxidation tests showed that fucoidan had an IC 50 of 1.250 mg I mL j1 and that the kappa, iota and lambda carrageenans had an IC 50 of 2.753 and 2.338 and 0.323 mg I mL j1 , respectively.Fucan fractions showed low antioxidant activity relative to fucoidan. These results clearly indicate the beneficial effect of algal polysaccharides as antioxidants.

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The brown algae Padina gymnospora contain different fucans. Powdered algae were submitted to proteolysis with the proteolytic enzyme maxataze. The first extract of the algae was constituted of polysaccharides contaminated with lipids, phenols, etc. Fractionation of the fucans with increasing concentrations of acetone produced fractions with different proportions of fucose, xylose, uronic acid, galactose, and sulfate. One of the fractions, precipitated with 50% acetone (v/v), contained an 18-kDa heterofucan (PF1), which was further purified by gel-permeation chromatography on Sephadex G-75 using 0.2 M acetic acid as eluent and characterized by agarose gel electrophoresis in 0.05 M 1,3 diaminopropane/acetate buffer at pH 9.0, methylation and nuclear magnetic resonance spectroscopy. Structural analysis indicates that this fucan has a central core consisting mainly of 3-ß-Dglucuronic acid 1→ or 4-ß-D-glucuronic acid 1 →, substituted at C-2 with α-L-fucose or ß-D-xylose. Sulfate groups were only detected at C-3 of 4-α-L-fucose 1→ units. The anticoagulant activity of the PF1 (only 2.5-fold lesser than low molecular weight heparin) estimated by activated partial thromboplastin time was completely abolished upon desulfation by solvolysis in dimethyl sulfoxide, indicating that 3-Osulfation at C-3 of 4-α-L-fucose 1→ units is responsible for the anticoagulant activity of the polymer. Correspondence

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Sulfated polysaccharides were extracted with acetone from brown algae Padina gymnospora. The fraction precipitated with 1.5 volumes of acetone (F1.5) purified in Sephadex G-75 was characterized by infrared and nuclear magnetic resonance of 13 C and 1 H, through which the presence of sulfate groups on the C4 of α-L-fucose could be observed. This polysaccharide showed that an MW of 25,000 Da was effective in reducing leukocyte influx into the peritoneal cavity in mice at 10 mg/kg and 25 mg/kg body weight, causing a decrease of 60 and 39%, respectively. In the present study, it was observed that this fucan has anti-inflammatory properties but no cytotoxic action, indicating its potential use in the pharmaceutical industry.