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.