Antiviral screening of British Columbian medicinal plants.

One hundred methanolic plant extracts were screened for antiviral activity against seven viruses. Twelve extracts were found to have antiviral activity at the non-cytotoxic concentrations tested. The extracts of Rosa nutkana and Amelanchier alnifolia, both members of the Rosaceae, were very active against an enteric coronavirus. A root extract of another member of the Rosaceae, Potentilla arguta, completely inhibited respiratory syncytial virus. A Sambucus racemosa branch tip extract was also very active against respiratory syncytial virus while the inner bark extract of Oplopanax horridus partially inhibited this virus. An extract of Ipomopsis aggregata demonstrated very good activity against parainfluenza virus type 3. A Lomatium dissectum root extract completely inhibited the cytopathic effects of rotavirus. In addition to these, extracts prepared from the following plants exhibited antiviral activity against herpesvirus type 1: Cardamine angulata, Conocephalum conicum, Lysichiton americanum, Polypodium glycyrrhiza and Verbascum thapsus.