Antiviral activity against H1N1 influenza was studied using ethnic medicinal plants of South India. Results revealed that Wrightia tinctoria (2.25 μg/ml) was one of the best antidotes against H1N1 virus in terms of inhibitory concentration of 50% (IC50) whereas the control drug Oseltamivir showed 6.44 μg/ml. Strychnos minor, Diotacanthus albiflorus and Cayratia pedata showed low cytotoxicity (>100) to the MDCK (Malin darby canine kidney) cells by cytotoxicity concentration of 50% (CC50) and possessed antiviral activity suggesting that these plants can be used as herbal capsules for H1N1 virus. W. tinctoria and S. minor showed high therapeutic indexes (TI) such as 12.67 and 21.97 suggesting that those plants can be used for anti-viral drug development. The CC50 values of Eugenia singampattiana (0.3 μg/ml), Vitex altissima (42 μg/ml), Salacia oblonga (7.32 μg/ml) and Salacia reticulata (7.36 μg/ml) resulted in cytotoxicity of the MDCK cells, due to their high phenolic content. Findings from this study state that the plant W. tinctoria can be a potent source for third generation anti-viral drug development against H1N1.
Keywords: Cytotoxicity; H1N1; Influenza; MDCK cells; SRB assay; Traditional knowledge.