Antiviral activity of Sargassum fluitans seaweed against echovirus 9, coxsackievirus A16 and coxsackievirus A24

Enteroviruses cause human diseases such as Mouth, Hand and Foot Syndrome, hemor rhagic conjunctivitis, aseptic meningitis, and viral meningoencephalitis. As yet, there is not specific therapy for most enteroviruses infections. The brown seaweeds of Sargassum genus synthesize a great variety of metabolites, which make them potential sources of compounds with antiviral activities. This study aimed to evaluate the in vitro antiviral activity of a hydro-alcoholic extract of Sargassum fluitans against three human enteroviruses: coxsackievirus A16, echovirus 9 and coxsackievirus A24. Cytotoxicity of the extract was evaluated in Vero, RD and Hep-2 cells by MTT method. Antiviral activity (EC50) was assessed by cytopathic effect inhibition in cells. Extracellular virucidal activity and reduction of viral yield were determined by endpoint viral titration assay. The antiviral activity was characterized by a time of addition assay. The extract showed antiviral inhibi- tory activity against all tested viruses. The extract also exhibited a virucidal effect against E9 and CVA16 and reduced the formation of infective particles in the cells in more than three logs. The extract was able to inhibit earlier and late stages in the enterovirus replication cycle. In conclusion, the present study demonstrated the effective in vitro antiviral activity of the brown seaweed Sargassum fluitans against clinically relevant enteroviruses, supporting their use as potential source of antiviral compounds.