Antiviral activity of Eupatorium adenophorum leaf extract against tobacco mosaic virus

Eupatorium adenophorum Spreng is a major invasive plant in China causing great economic losses. Considerable effort has been expended searching for new and innovative methods for integrative management of this species. In this study, an E. adenophorum extract was tested for antiviral activity against tobacco mosaic virus (TMV) using the local lesion assay method, and also characterized. The E. adenophorum leaf extract was able to strongly inhibit TMV infection, with electron microscopic observations indicating that the virus particles had been disaggregated. The active components in the extract are thermostable, stable at acidic pH, and largely not dialyzable. Tobacco seedlings treated with the extract exhibited significantly elevated superoxide dismutase, peroxidase, and polyphenol oxidase activities. Our results—the first reported observations of antiviral activity from leaf extracts of E. adenophorum — suggest that this species is a promising source of antiviral substances for practical use. •Eupatorium adenophorum leaf extract contains a potent inhibitor against TMV.•The putative inhibitor is thermostable, stable at acidic pH, and not dialyzable.•The antiviral mechanism involves virion inhibition and promotion of host response.