Antiviral activities in plants endemic to madagascar.

In order to determine the potential of Malagasy plants as sources of antiviral activities, ethanolic extracts of 11 plants, endemic to Madagascar, were evaluated for antiviral activities. Nine of the extracts had significant activity against herpes simplex virus (HSV), whereas only four were active against Sindbis virus. Five extracts: Cynometra cloiselii , Cynometra madagascariensis , Evonymopsis longipes , Ravensara retusa , and Terminalia monoceros were particularly potent and could completely inactivate the HSV test inoculum (100 infectious virus particles) at concentrations of less than 25 µg/ml. Most of the active phytochemicals were photosensitizers. However, the combined properties of the active extracts indicated the presence of distinct compounds in different species. On the basis of these results we believe that it would be worthwhile expanding these studies to include additional species of Malagasy plants.