Search for antiviral activity in higher plant extracts.

In the course of our search for plant natural products as antiviral agents, extracts of ten plants from the Iberian Peninsula were tested for antiviral activity against herpes simplex type I (HSV-1), vesicular stomatitis virus (VSV) and poliovirus type 1. Aqueous extracts of five of these medicinal plants, namely Nepeta nepetella (150-500 microg/mL), Nepeta coerulea (150-500 microg/mL), Nepeta tuberosa (150-500 microg/mL), Dittrichia viscosa (50-125 microg/mL) and Sanguisorba minor magnolii (50-125 microg/mL), showed a clear antiviral activity against two different DNA and RNA viruses, i.e. HSV-1 and VSV. Only the medicinal plant Dittrichia viscosa was active against an additional virus, poliovirus type 1.