Bioactivity directed fractionation of the chloroform extract of the root bark of Maytenus senegalensis resulted in the isolation and characterization of the quinonemethide triterpene, (20α)-3-hydroxy-2-oxo-24-nor-friedela-1(10) ,3,5,7-tetraen-carboxylic acid-(29)-methylester (pristimerin). The structure was elucidated by spectroscopic techniques. The in vitro antiplasmodial activity of the isolated compound against chloroquine-resistant strain (Dd2) of Plasmodium falciparum was IC₅₀ = 0.5μg/ml and its in vitro antileishmanial activity performed on promostigotes of Leishmania major was IC50 = 6.8 ± 0.8 μg/ml while the cytotoxicity on lymphocyte proliferation model was detected at IC50= 6.8 ± 0.8 μg/ml.