Polyalthia longifolia leaves methanolic extract targets entry and budding of viruses-an in vitro experimental study against paramyxoviruses.

Synthetic antiviral drugs have several limitations including high cost. Thus research on antiviral property of medicinal plants is continuously gaining importance. Polyalthia longifolia possesses several medicinal properties and has been used in traditional ayurvedic medicine for treatment of dermatological ailments as kushta, visarpa/herpes virus infection and also to treat pyrexia of unknown origin as mentioned in Visarpa Chikitsa.Keeping in view the cytotoxic, anti-cancer activity and antiviral efficacy of Polyalthia longifolia against herpes, present study was undertaken to evaluate the in vitro antiviral activity of methanolic extract of Polyalthia longifolia leaves, if any, and to unravel the possible target(s)/mechanism of action.Antiviral activity of Polyalthia longifolia methanolic extract was studied using Vero cell lines against paramyxoviruses, namely-peste des petits ruminants virus (PPRV) and Newcastle disease virus (NDV). Cytotoxicity of the test extract was evaluated employing MTT assay. Virucidal activity, and viral-attachment, virus entry and release assays were determined in Vero cells using standard experimental protocols. The viral RNA in the virus-infected cells was quantified by qRT-PCR.At non-cytotoxic concentration, methanolic extract of Polyalthia longifolia leaves was found to inhibit the replication of PPRV and NDV at viral entry and budding level, whereas other steps of viral life cycle such as attachment and RNA synthesis remained unaffected.Polyalthia longifolia leaves extract possesses promising antiviral activity against paramyxoviruses and acts by inhibiting the entry and budding of viruses; and this plant extract evidently possesses excellent and promising potential for development of effective herbal antiviral drug.