The aim of the present study was to evaluate the antiviral activity of ethanol extracts from Ficus binjamina and Lilium candidum in vitro. Ficus binjamina is known to be resistant to various plant viruses, while Lilium candidum has a high susceptibility to plant viruses [1]. Vero cells and Herpes Simplex Virus -1 and 2 (HSV-1, HSV-2) and Varicella-Zoster Virus (VZV) were used. The toxicity of the extracts was tested by three methods: direct account, observation of morphological changes by optical inverted microscope and MTT assay. Evaluation of viral infection was performed by cytopathic effect examination and plaque assay. No cytotoxic effect was observed at concentrations over 100µg/ml in all examined extracts. Extract of F. binjamina fruits had no effect on HSV-1 and HSV-2 infection, while significantly inhibited VZV infection with IC50 of 10µg/ml (p<0.001). Stems of F. binjamina, bulbs and petals of L. candididum didn't show significant antiviral properties. Leaf extracts of F. binjamina inhibited all studied viruses. L. candidum leaf extracts had no effect on VZV but strongly inhibited HSV-1 and slightly HSV-2. There was an indirect evidence for strong interactions between the plant extracts and the viruses and weak interactions with the cell surface. It is suggested that plant extracts exerted their anti-herpetic effect mainly by blocking the virus access to the host cells.
References: [1] Petrov, D.B. et al. (1974) Journal of Botany 4:23–26.
