Polysaccharides extracted from the red seaweed Acanthophora spicifera. Chemical structure and antiviral activity

NOSEDA MIGUEL; DUCCATTI DIOGO; CAUDURO J; NOSEDA DIEGO GABRIEL; PUJOL CARLOS; DUARTE EUGENIA

San Pablo

Congreso; Reunion Anual de la Sociedad Brasilera de Bioquímica; 2000

Sociedad Brasilera de Bioquimica (SBBq)

The red seaweed biosynthesized a great variety of sulfated galactans, some of these polysaccharides have been described as inhibitors of the replication of several enveloped viruses. We report herein the chemical structure of the sulfated polysaccharides produced by A. spicifera and the antiherpetic properties of the macromolecules. The polysaccharides of A. spicifera were extracted with water at 25°C and 70°C, yielding the crude extracts ACW and AHW-I and -II. Gal and 3,6-AnGal were the principal  monosaccharide components of these extracts, accounting for 76-84 mol% of the total sugars. Small quantities of mono-O-methyl Gal, 2-O-Me-3,6-AnGal, Xyl and Glc were also present, together with the sulfate groups and pyruvic acid. AHW-I was separated by anion-exchange chromatography, into seven fractions that showed as the crude extracts negative specific rotations indicating that they are galactans with an agar background. NMR and chemical analysis of the native alkali treated polysaccharides indicated that the pyruvic acetal is in the R form and 4,6 linked to the â-gal units. These residues are highly sulfated at C-2 and the á-L-units are present in varying degrees as 3, 6-An Gal or its biological precursor, Gal 6-sulfate. All the fractions were evaluated for antiviral activity against HSV-1 and -2 by reduction plaque assay. The concentration of polysaccharide required to inhibit 50% of viral plaques was lower than 0.6 ìg/mL in same samples, with out cytotoxic effects against Vero cells. These results showed that the naturally sulfated, pyruvated galactans produced by A. spicifera are potent antiherpetic compounds.