Herpes simplex virus-inhibitory sulfated xylogalactans from the red seaweed Nothogenia fastigiata

Two sulfated xylogalactans (F1 and F7), isolated from the red seaweed Nothogenia fastigiata, achieved a dose-dependent inhibition of the replication of herpes simplex virus type 1 (HSV-1) in Vero cells, with 50% effective doses in the range of 15.0-32.6 mu g/ml, and without affecting cell viability at concentrations up to 200 mu g/ml. The presence of sulfate groups in the molecule was essential for the antiviral properties of these polysaccharides. F7 afforded significant inhibition in HSV-1 yield if added to the cell cultures simultaneously with virus inoculum, but had no effect when it was added after Ih of infection. Analysis of the early events of the viral replicative cycle showed that the anti-HSV effect of F7 was due to a specific inhibition of virus attachment to the host cell whereas virus internalization was not impaired.