Antiviral activity of Chinese medicine-derived phytochemicals against avian influenza A (H5N1) virus.

In 1997, a highly pathogenic avian influenza A virus (H5N1) in Hong Kong caused death in 6 of 18 infected persons.1 Subsequent outbreaks of H5N1 avian influenza in several other countries indicated that the virus may be more widely established among the bird population and the environment than previously thought. Human deaths from avian influenza infections have been reported in Indonesia, Vietnam, Thailand, and China. Fortunately, there was no evidence of large-scale human-to-human transmission of the virus. To date only two classes of anti-influenza drugs (amantadine and its derivatives and neuraminidase inhibitors) have been clinically used, but their use may result in the emergence of resistant variants.2 Phytochemicals such as phenolic compounds, flavonoids3,4 and proteins such as cyanovirin-N5 from natural sources may have significant inhibitory effects on influenza A viruses. Our laboratory has isolated, purified, experimentally tested, and identified more than 30 potent antiviral herbal extracts and active compounds that significantly inhibit various human viruses. Three proteins isolated from Pandanus amaryllifolius (PYM2), Narcissus tazett (NTL), and Polygonatum odoratum (POL) were identified to have most prominent anti-H5N1 potency. Their antiviral efficacy and potential as a product was investigated. K e y M e s s a g e s