Improvement of Aglycone π-Stacking Yields Nano- to Subnanomolar FimH Antagonists.

Antimicrobial resistance has become a serious concern for the treatment of urinary tract infections. In this context, an anti-adhesive approach targeting FimH, a bacterial lectin enabling the attachment of E. coli to host cells, has attracted considerable interest. FimH can adopt a low/medium-affinity state in the absence and a high-affinity state in the presence of shear forces. Until recently, mostly the high-affinity state has been investigated, despite the fact that a therapeutic antagonist should bind predominantly to the low-affinity state. In this communication, we demonstrate that fluorination of biphenyl alpha-d-mannosides leads to compounds with perfect pi-pi stacking interactions with the tyrosine gate of FimH, yielding low nanomolar to sub-nanomolar K-D values for the low- and high-affinity states, respectively. The face-to-face alignment of the perfluorinated biphenyl group of FimH ligands and Tyr48 was confirmed by crystal structures as well as H-1,N-15-HSQC NMR analysis. Finally, fluorination improves pharmacokinetic parameters predictive for oral availability.