In vitro activity of artemisinin, its derivatives, and pyronaridine against different strains of Plasmodium falciparum

Abstract

The activities of artemisinin (qinghaosu), dihydroartemisinin (dihydroqinghaosu), artemether and pyronaridine were tested in a 48 h in vitro assay against 3 chloroquine-sensitive and one chloroquine-resistant strains of Plasmodium falciparum. Growth inhibition was modelled with a sigmoid E_max model. All compounds markedly inhibited the growth of all strains although, for the chloroquine-resistant strain, merozoites were detected at concentrations as high as 10⁻⁴m of artemisinin, dihydroartemisinin and artemether. Dihydroartemisinin, artemether and pyronaridine appeared to be more potent than artemisinin, with EC₅₀ values of 4·7–23 nm, 0·98–6·1 nm and 4·4–18 nm respectively, while the EC₅₀ value of artemisinin was 3–108 nm against all 4 strains.