Antimalarial activity of Aspilia pruliseta, a medicinal plant from Uganda

Aspilia pruliseta Schweinf. (Asteraceae) is a medicinal plant indigenous to Uganda and the neighboring countries of East Africa. It has been used extensively by the rural population for the treatment of fevers and malaria. During the antimalarial evaluation of this plant, four nontoxic diterpenes were isolated that possessed moderate activity against chloroquine-sensitive (D6) and chloroquine-resistant (W2) clones of Plasmodium falciparum, with IC(50) values ranging from 14 to 23 µM. These moderately active compounds included the previously undescribed diterpene, ENT-15 β-senecioyloxy-16,17-epoxy-kauran-18-oic acid that demonstrated an IC(50) value of 23.4 µM against clone D6, but was devoid of activity against clone W2. Four additional diterpenes were obtained from the aerial parts of A. pruliseta, but these known compounds were essentially inactive. The moderate activities of select diterpenes of A. pruliseta could account collectively for the historical and enduring use of this plant in traditional African medicine.