Discovery of a rhodanine class of compounds as inhibitors of Plasmodium falciparum enoyl-acyl carrier protein reductase.

Enoyl acyl carrier protein (ACP) reductase, one of the enzymes of the type II fatty acid biosynthesis pathway, has been established as a promising target for the development of new drugs for malaria. Here we present the discovery of a rhodanine (2-thioxothiazolidin-4-one) class of compounds as inhibitors of this enzyme using a combined approach of rational selection of compounds for screening, analogue search, docking studies, and lead optimization. The most potent inhibitor exhibits an IC(50) of 35.6 nM against Plasmodium falciparum enoyl ACP reductase (PfENR) and inhibits growth of the parasite in red blood cell cultures at an IC(50) value of 750 nM. Many more compounds of this class were found to inhibit PfENR at low nanomolar to low micromolar concentrations, expanding the scope for developing new antimalarial drugs. The structure-activity relationship of these rhodanine compounds is discussed.