Identification of novel imidazo[1,2-a]pyridine inhibitors targeting M. tuberculosis QcrB

PLoS One. 2012;7(12):e52951. doi: 10.1371/journal.pone.0052951. Epub 2012 Dec 31.

Abstract

Mycobacterium tuberculosis is a major human pathogen and the causative agent for the pulmonary disease, tuberculosis (TB). Current treatment programs to combat TB are under threat due to the emergence of multi-drug and extensively-drug resistant TB. Through the use of high throughput whole cell screening of an extensive compound library a number of imidazo[1,2-a]pyridine (IP) compounds were obtained as potent lead molecules active against M. tuberculosis and Mycobacterium bovis BCG. The IP inhibitors (1-4) demonstrated minimum inhibitory concentrations (MICs) in the range of 0.03 to 5 µM against a panel of M. tuberculosis strains. M. bovis BCG spontaneous resistant mutants were generated against IP 1, 3, and 4 at 5× MIC and subsequent whole genome sequencing identified a single nucleotide polymorphism (937)ACC>(937)GCC (T313A) in qcrB, which encodes the b subunit of the electron transport ubiquinol cytochrome C reductase. This mutation also conferred cross-resistance against IP 1, 3 and 4 demonstrating a common target. Gene dosage experiments confirmed M. bovis BCG QcrB as the target where over-expression in M. bovis BCG led to an increase in MIC from 0.5 to >8 µM for IP 3. An acute murine model of TB infection established bacteriostatic activity of the IP series, which await further detailed characterization.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antitubercular Agents / chemical synthesis
  • Antitubercular Agents / pharmacology*
  • Antitubercular Agents / therapeutic use
  • Dogs
  • Humans
  • Mice
  • Microbial Sensitivity Tests
  • Microsomes, Liver / drug effects
  • Mycobacterium bovis / drug effects*
  • Mycobacterium tuberculosis / drug effects*
  • Pyridines / antagonists & inhibitors*
  • Rats
  • Tuberculosis / drug therapy*
  • Tuberculosis / prevention & control

Substances

  • Antitubercular Agents
  • Pyridines
  • imidazo(1,2-a)pyridine

Grants and funding

GSB acknowledges support in the form of a Personal Research Chair from Mr. James Bardrick and a Royal Society Wolfson Research Merit Award. The research leading to these results has received funding from the European Union’s 7th Framework Programme (FP7- 2007–2013) under grant agreement no 261378. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.