Hit-to-Lead Optimization of Energy-Coupling Factor (ECF) Transporter Inhibitors as Novel Antibiotic.

Multiparameter optimization of a previously identified class of inhibitors of the energy-coupling factor (ECF) transporters enabled the confirmation of in vivo efficacy. ECFs are a class of transmembrane proteins that play a vital role in the active translocation of essential nutrients across cell membranes and are therefore important in the fight against antimicrobial resistance. Aiming to improve the drug-like properties of our inhibitory class, we performed a focused structure-activity relationship study around the Eastern part of our starting molecule 3 by exploiting click chemistry. Our multiparameter optimization resulted in compounds with enhanced metabolic stability and solubility, potent activity against both a panel of Gram-positive bacteria, and against the ECF transporters. We further demonstrate rapid bacterial killing using Enterococcus faecium as a model organism and confirmed in vivo efficacy of the best compounds in Galleria mellonella larvae and Danio rerio (zebrafish) infection models, highlighting the therapeutic potential of our approach.