Antimalarial activity of simalikalactone E, a new quassinoid from Quassia amara L. (Simaroubaceae)Cachet, N.Hoakwie, F.Bertani, S.Bourdy, GenevièveDeharo, EricStien, D.Houel, E.Gornitzka, H.Fillaux, J.Chevalley, SéverineValentin, A.Jullian, ValérieWe report the isolation and identification of a new quassinoid named simalikalactone E (SkE), extracted from a widely used Amazonian antimalarial remedy made out of Quassia amara L. (Simaroubaceae) leaves. This new molecule inhibited the growth of Plasmodium falciparum cultured in vitro by 50%, in the concentration range from 24 to 68 nM, independently of the strain sensitivity to chloroquine. We also showed that this compound was able to decrease gametocytemia with a 50% inhibitory concentration sevenfold lower than that of primaquine. SkE was found to be less toxic than simalikalactone D (SkD), another antimalarial quassinoid from Q. amara, and its cytotoxicity on mammalian cells was dependent on the cell line, displaying a good selectivity index when tested on nontumorogenic cells. In vivo, SkE inhibited murine malaria growth of Plasmodium vinckei petteri by 50% at 1 and 0.5 mg/kg of body weight/day, by the oral or intraperitoneal routes, respectively. The contribution of quassinoids as a source of antimalarial molecules needs therefore to be reconsidered.2009texthttp://www.documentation.ird.fr/hor/PAR00004140oai:ird.fr:PAR00004140Cachet N., Hoakwie F., Bertani S., Bourdy Geneviève, Deharo Eric, Stien D., Houel E., Gornitzka H., Fillaux J., Chevalley Séverine, Valentin A., Jullian Valérie. Antimalarial activity of simalikalactone E, a new quassinoid from Quassia amara L. (Simaroubaceae). Antimicrobial Agents and Chemotherapy, 2009, 53 (10), p. 4393-4398.