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.