Antiviral effect of Sanicula europaea L. leaves extract on influenza virus-infected cells.

We have investigated the influence of Sanicula europaea L. extracts on influenza virus growth in MDCK cells. Fractions I, II, and III separated from Sanicula extract with Sephadex column chromatography were found to be non-toxic against MDCK cells. The growth of influenza A/PR/8/34 was completely inhibited by these fractions, while that of influenza B/Lee/40 was not affected. Fractions II and III have been shown not to have a direct virucidal activity on influenza A/PR/8/34. Influenza A/Vic/1/75 produced microscopic plaques in the presence of the extract. In vitro RNA synthesis with viral RNA-dependent RNA polymerase was also inhibited by a water soluble extract of Sanicula. These observations suggest that the Sanicula extract contains an anti-influenza virus substance.