Synthesis and Evaluation of Antiplasmodial Activities of Fluorinated 6-Amino- 2-Aryl-3H-Indolone-N-Oxides

A series of novel 6-amino-2-aryl-3H-indolone-N-oxides were synthesized at yields of up to 65% and characterized; one was further characterized using X-ray crystallographic analysis. Synthesized compounds were evaluated for their in vitro activity against a chloroquine-resistant (FcB1) strain of Plasmodium falciparum, as well as for the 50% cytotoxic concentration (CC50) on Vero cell lines. The most promising activities were observed for the fluorinated compounds, the most active in vitro being 6-(2-morpholinoacetamido)-2-(4-(trifluoromethoxy) phenyl)-3H-indolone-N-oxide (IC50: 15.5 nM). In addition, these compounds showed weak cytotoxicity leading to selectivity index values of u003e170, thus warranting further in vitro and in vivo studies.