Combined antiinfluenza virus activity of Flos verbasci infusion and amantadine derivatives.

The infusion prepared from flowers of Verbascum thapsiforme Schrad. (Scrophulariaceae) (FVI) reduced the infectious and haemagglutination yields of a range of influenza viruses in tissue cultures. Amantadine hydrochloride is an accepted and well studied selective inhibitor of influenza virus reproduction. The combined application of the plant preparation FVI and three amantadine derivatives resulted in a marked enhancement of the inhibitory effect of FVI on the reproduction of influenza virus A/chicken/Germany/27, strain Weybridge (H7N7) in cell cultures of chicken embryo fibroblasts. The antiviral activity was determined by the difference in the infectious titres of control and treated viruses. The combined effect was defined on the basis of infectious viral yields. The most pronounced enhancement was shown for the combination of FVI and adamantanamine glucuronide.