Sulfated xylomannans from the red seaweed Sebdenia polydactyla: structural features, chemical modification and antiviral activity.

BACKGROUND Many viruses display affinity for cell surface heparan sulfate proteoglycans with biological relevance in virus entry. This raises the possibility of the application of sulfated polysaccharides in antiviral therapy. METHODS In this study, we analysed polysaccharide fractions isolated from Sebdenia polydactyla. RESULTS The purified xylomannan sulfate and its further sulfated derivatives showed strong activity against herpes simplex virus type-1 (HSV-1). Their 50% inhibitory concentration values were in the range 0.35-2.8 microg/ml and they lacked cytotoxicity at concentrations up to 1,000 microg/ml. The major polysaccharide, which had 0.6 sulfate groups per monomer unit and an apparent molecular mass of 150 kDa, contained a backbone of alpha-(1-->3)-linked d-mannopyranosyl residues substituted at position 6 with a single stub of beta-d-xylopyranosyl residues. CONCLUSIONS The degree of sulfation seemed to play an important role because desulfation and/or further sulfation of the isolated macromolecules largely influenced their in vitro anti-HSV-1 activity.