ABSTRACT
Objective: To study the antiviral effect of polysaccharides from brown seaweed Lobophora variegata. Method: The crude polysaccharide was extracted with boiling water and precipitated with ethanol,and then fractionated with ion exchange chromatography. Its antiviral activity was tested by cytopathic effect (CPE) reduction assay and plaque reduction assay. The cytotoxicity of the water crude extract was determined by MTT method. Results: The crude water extract showed markedly antiviral activity against herpes simplex virus (HSV) type 1 and type 2 including ACV resistant strain and clinical strains with low EC50 values of 18.2 and 6.25 μg/ml respectively. It also showed very low cytotoxicity to Vero, HEp-2 and MDCK cells. Therefore, the crude extract possessed high selective index for antiviral effect. It also had some inhibitory effect on respiratory syncytial virus (RSV) but had no effect on influenza A virus. Two fractions were isolated from the water crude extract and they exhibited anti-HSV activity in the test of CPE reduction assay in Vero cells. Conclusion: Seaweed Lobophora variegata contains antiviral polysaccharides with high inhibitory effect on herpes simplex virus.