Design, Synthesis, and Biological Evaluation of Multiple Targeting Antimalarials.

Malaria still threatens global health seriously today. While the current discoveries of antimalarials are almost totally focused on single mode-of-action inhibitors, multi-targeting inhibitors are highly desired to overcome the increasingly serious drug resistance. Here, we performed a structure-based drug design on mitochondrial respiratory chain of Plasmodium falciparum and identified an extremely potent molecule, RYL-581, which binds to multiple protein binding sites of P. falciparum simultaneously (allosteric site of type II NADH dehydrogenase, Qo and Qi sites of cytochrome bc1). Antimalarials with such multiple targeting mechanism of action have never been reported before. RYL-581 kills various drug-resistant strains in vitro and shows good solubility as well as in vivo activity. This structure-based strategy for designing RYL-581 from starting compound may be helpful for other medicinal chemistry projects in the future, especially for drug discovery on membrane-associated targets.