<i>In vitro</i> and <i>in vivo</i> animal model antitrypanosomal evaluation of ten medicinal plant extracts from south west Nigeria

Abstract

The relative antitrypanosomal and haemolytic activities of the methanol extracts of 10 Nigerian medicinal plants extracts comprising of the leaf, stem bark and root bark of Afzelia africana, Khaya senegalensis and Terminalia superba as well as the leaf extract of Lannea welwistchii were investigated. All the extracts showed varying degrees of trypanocidal activity in vitro. The roots of T. superba and K. senegalensis, the stem of T. superba and the leaf of A. africana were the most effective with a minimum lethal concentration (MLC) of 3 mg/ml; compared to 5.4 mg/ml for diminazene aceturate (Berenil®), the reference drug. A. africana stem bark also had an MLC of 5.4 mg/ml in the study. The extracts were also analyzed for hemolytic activity, using washed bovine red blood cells in order to ascertain if any relationship between their hemolytic and antitrypanosomal activities. In the in vivo
analysis, only the T. superba root bark extract totally inhibited the growth of parasites in both rats and mice; all the other root bark extracts resulted in parasite clearance in rats only. The duration of
clearance in all cases was 48 h, with relapse parasitaemia occurring on the 3rd day post-administration of the extracts.