Antiplasmodial Activity of Constituents Isolated fromCroton lobatus.

Seven constituents were isolated from the stems and leaves of Croton lobatus. L. (Euphorbiaceae), a medicinal plant used in western Africa in traditional folk medicine to cure malaria, pregnancy troubles, and dysentery. Their structures were elucidated by spectroscopic methods. The compounds identified were 3-(6Z.,9Z.)dodeca-6,9-dienoyloxy-2-octanoyloxypropyl(6Z.,9Z.)dodeca-6,9-dienoate (1) for the first time and six known compounds: (Z.,Z.,Z.)-9,12,15-octadecatrienoic acid methyl ester (2), 8,11,17,21-tetramethyl-(E.,E.,E.,E.)-8,10,17,21-tetraentetracosanoic acid (3), geranylgeraniol (4), cholestan-3-one (5), betulinic acid (6), and (E.)-3-(4-methoxy-phenyl)-2-phenyl-acrylic acid (7). From the seven compounds, (4) and (6) showed the best antiplasmodial activity in vitro. on Plasmodium falciparum. K1 chloroquine-resistant strain, with IC50 values (µg/mL) of 1.07 and 1.45 mg/mL, respectively, while compounds (2), (3), and (7) showed IC50 below 5 in the same assay. Cytotoxicity of the most active compounds was evaluated on L6 murine myoblast cells. Geranylgeraniol (4) showed good selectivity with an SI value (SI = ratio of cytotoxicity to biological activity) over 25.