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薬理と治療
Abstract
Background The branches of the Kuromoji(Lindera umbellata Thunb.)have long been used as a herbal medicine and in modern times as an ingredient for medicinal liquor. We have reported that a hot-water extract of branches of Kuromoji (Kuromoji extract)has a sustained suppressive effect on the growth of type-A influenza virus strain. In this study, we investigated the efficacy of Kuromoji extract against other type-A influenza virus strains and the point of action of its antiviral activity. Methods The inhibitory effect of Kuromoji extract on the cytopathic effect by swine-origin pandemic influenza virus strain and its oseltamivir-resistant variant was investigated. The most effective time of treatment with Kuromoji extract in viral infection was examined by quantifying viral RNA and viral protein expression in host cells. The effect on the viral adsorption process was examined by hemagglutination inhibition test. Results The anti-influenza virus activity of Kuromoji extract against human influenza A viruses including swine-origin influenza strains and its oseltamivir-resistant variant and was observed. Kuromoji extract was most effectively suppressed viral mRNA expression in host cells when added 0-30 min after the virus inoculation. In the presence of Kuromoji extract, inhibition of hemagglutination by the virus was observed. In comparison with the inactivating effect on virus particle, host cell︱mediated inhibitory effect on viral growth was exerted even at a lower concentration. Conclusions Kuromoji extract was suggested to suppress the process from adsorption to uncoating in influenza virus infection mainly by the action via host cells. We believe Kuromoji extract is one of the useful functional food materials that prevent influenza virus infection.
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