N-Hydroxyformamide LpxC inhibitors, their in vivo efficacy in a mouse Escherichia coli infection model, and their safety in a rat hemodynamic assay

Bioorg Med Chem. 2020 Dec 15;28(24):115826. doi: 10.1016/j.bmc.2020.115826. Epub 2020 Oct 28.

Abstract

UDP-3-O-(R-3-hydroxyacyl)-N-acetylglucosamine deacetylase (LpxC), the zinc metalloenzyme catalyzing the first committed step of lipid A biosynthesis in Gram-negative bacteria, has been a target for antibacterial drug discovery for many years. All inhibitor chemotypes reaching an advanced preclinical stage and clinical phase 1 have contained terminal hydroxamic acid, and none have been successfully advanced due, in part, to safety concerns, including hemodynamic effects. We hypothesized that the safety of LpxC inhibitors could be improved by replacing the terminal hydroxamic acid with a different zinc-binding group. After choosing an N-hydroxyformamide zinc-binding group, we investigated the structure-activity relationship of each part of the inhibitor scaffold with respect to Pseudomonas aeruginosa and Escherichia coli LpxC binding affinity, in vitro antibacterial potency and pharmacological properties. We identified a novel, potency-enhancing hydrophobic binding interaction for an LpxC inhibitor. We demonstrated in vivo efficacy of one compound in a neutropenic mouse E. coli infection model. Another compound was tested in a rat hemodynamic assay and was found to have a hypotensive effect. This result demonstrated that replacing the terminal hydroxamic acid with a different zinc-binding group was insufficient to avoid this previously recognized safety issue with LpxC inhibitors.

Keywords: Antibacterial; Escherichia coli; Klebsiella pneumoniae; LpxC; Pseudomonas aeruginosa.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amidohydrolases / antagonists & inhibitors*
  • Amidohydrolases / metabolism
  • Animals
  • Anti-Bacterial Agents / chemistry
  • Anti-Bacterial Agents / metabolism
  • Anti-Bacterial Agents / pharmacology*
  • Anti-Bacterial Agents / therapeutic use
  • Binding Sites
  • Crystallography, X-Ray
  • Disease Models, Animal
  • Enzyme Inhibitors / chemistry*
  • Enzyme Inhibitors / metabolism
  • Enzyme Inhibitors / pharmacology
  • Enzyme Inhibitors / therapeutic use
  • Escherichia coli / drug effects
  • Escherichia coli Infections / drug therapy
  • Escherichia coli Infections / pathology
  • Female
  • Formamides / chemistry*
  • Formamides / metabolism
  • Formamides / pharmacology
  • Formamides / therapeutic use
  • Half-Life
  • Hemodynamics / drug effects*
  • Male
  • Mice
  • Molecular Dynamics Simulation
  • Rats
  • Rats, Sprague-Dawley
  • Structure-Activity Relationship

Substances

  • Anti-Bacterial Agents
  • Enzyme Inhibitors
  • Formamides
  • formamide
  • Amidohydrolases
  • UDP-3-O-acyl-N-acetylglucosamine deacetylase