Anti-viral activities of herbal preparations

Upper respiratory tract infections (URI) represent the most frequent infectious disease in the western civilisation and 90–95% are of viral origin [1]. Many herbal cold remedies own anti-viral activity, which in some cases is directed to viruses not involved in respiratory infections and the term „antiviral“ in the context of their use maybe misleading. In our experiments we compared different herbal preparations, which are traditionally used for the treatment of URI. Thirty (30) preparations from twenty (20) plants were tested for their antiviral activity against the most frequent cold viruses. No significant effect was observed against RV or adenovirus for any of the extracts tested. Membrane-coated viruses like influenza, RSV or HSV were more sensitive to the samples. Mentha piperita, Pelargonium sidoides and Cistus incanus extracts showed moderate to strong activity against H3N2 virus and Tilia ssp and Sambucus nigra were effective against RSV. Only weak activity was observed against HSV by Tilia ssp and Sambucus nigra. A combination product of E. purpurea herba and root showed extraordinary antiviral effects against influenza, RSV and HSV simultaneously. The effects exceeded the otherwise measured by a factor 4 to 40. Our experiments indicate that many traditionally used plant extract exhibit moderate effects on virulence or replication of the most prominent cold viruses. Some extracts exhibit activity against a particular virus but not against others. A special E. purpurea extract however did show remarkable anti-viral activity against different respiratory viruses at physiologically relevant concentrations.

Acknowledgements: Funding from Bioforce AG Switzerland.

References: 1. Gwaltney JM. Clinical significance and pathogenesis of viral respiratory infections. The American Journal of Medicine. 2002;112 (6A):13–18.