Antimalarial activity of simalikalactone E, a new quassinoid from Quassia amara L. (Simaroubaceae) Cachet, N. Hoakwie, F. Bertani, S. /Bourdy, Geneviève /Deharo, Eric Stien, D. Houel, E. Gornitzka, H. Fillaux, J. /Chevalley, Séverine Valentin, A. /Jullian, Valérie We 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. 2009 text https://www.documentation.ird.fr/hor/PAR00004140 PAR00004140 Cachet 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). 2009, 53 (10), 4393-4398 EN