Inhibition of viral adsorption and penetration by an aqueous extract from Rhododendron ferrugineum L. as antiviral principle against herpes simplex virus type-1.

The polyphenol-enriched aqueous extract RF from the aerial parts of Rhododendron ferrugineum exhibited strong antiviral activity against herpes simplex virus type-1 while adenovirus 3 was not affected. RF exhibited an IC(50) of 7.4 μg/mL and a selectivity index of 64 when added to the virus inoculum prior to infection.