Trypanocidal Activity of 50% Methanolic Extract of Khaya Senegalensis Tree Bark

Abstract

In our ongoing research for new leads to the development of trypanocide from medicinal plants, due to emerged resistant strains of trypanosomes, Khaya senegalensis tree bark was extracted with methanolic solvent. K. senegalensis tree bark at different concentrations ((250-1000 µg ml-1) was screened against Trypanosoma evansi on Alsever’s medium. Trypanosomes were suspended in Alsever’s solution with inactivated bovine serum at 58oC for 1 h.  180 µl of the medium was added to the MPE of K. senegalensis tree back (20 µl) and incubated at 37oC with 5% carbon dioxide for 4 h. On hourly basis, drops of the incubated mixture were observed under inverted microscope for antitrypanosomal activity. In vitro cytotoxicity of MPE of K. senegalensis tree bark at concentrations (1.56-100 µg ml-1) was done on Vero cells grown in Dulbecco's Modified Eagle Medium (DMEM) at appropriate conditions. At 250 µg ml-1of 50% MPE of K. senegalensis, there was drastic reduction in trypanosomes count (40.00±0.0±10.33±0.88) and at 1000 µg ml-1 (40.00±8.000±0.58) at 5 h of incubation though no complete killing of trypanosomes in any of the ELISA plate wells was observed. But at 1000 µg ml-1 of 100% MPE of K. senegalensis, trypanosomes were not detected in the ELISA plate wells at 5 h of incubation. Significant trypanocidal activity was observed (P ≤ 0.05 to 0. 01). Both MPE of K. senegalensis and diminazine aceturate were cytotoxic to Vero cells in all concentrations except at concentrations of 1.56-6. 25 µg ml-1 and 1.56-6. 25µg ml-1. This result indicated that K. Senegalensis tree bark possessed trypanocidal compounds that may lead to discovery of new trypanocide and Alsever’s medium supported the trypanocidal activity observed.