CONICET | Buscador de Institutos y Recursos Humanos

Room-temperature acid (pH 2) extraction of Dictyota dichotoma thalli yielded 2.2% of sulfated polysaccharides. Further extraction with the same solvent at 70 C was conducted sequentially for nine times, with a total yield of 7.2%. Fucose was the main monosaccharide only in the room-temperature extract and in the first 70 C extract. The remaining fractions showed increasing amounts of mannose (the main neutral monosaccharide), xylose and uronic acids. Fractionation by means of cetrimide precipitation and redissolution in increasing sodium chloride solutions has allowed obtaining several subfractionsfrom each extract. The fractions redissolved at lower NaCl concentrations have large amounts of uronicacids and lesser sulfate contents, whereas those redissolved at higher NaCl concentrations are heavilysulfated and have low uronic acid contents. For the fucose-rich extracts , fractionation leads to uronoxylomannofucan-rich and galactofucan-rich fractions. The remaining extracts gave rise to complex mixtures, with mannose and uronic acid-rich polysaccharides. Moderate inhibitory effect against herpes virus (HSV-1) and Coxsackie virus (CVB3) were found for the galactofucan-rich fractions.Most of the other fractions were inactive against both viruses, although some xylomannan-rich fractions were also active against HSV-1.