Indole Based Weapons to Fight Antibiotic Resistance: A Structure-Activity Relationship Study

J Med Chem. 2016 Feb 11;59(3):867-91. doi: 10.1021/acs.jmedchem.5b01219. Epub 2016 Jan 26.

Abstract

Antibiotic resistance represents a worldwide concern, especially regarding the outbreak of methicillin-resistant Staphylococcus aureus, a common cause for serious skin and soft tissues infections. A major contributor to Staphylococcus aureus antibiotic resistance is the NorA efflux pump, which is able to extrude selected antibacterial drugs and biocides from the membrane, lowering their effective concentrations. Thus, the inhibition of NorA represents a promising and challenging strategy that would allow recycling of substrate antimicrobial agents. Among NorA inhibitors, the indole scaffold proved particularly effective and suitable for further optimization. In this study, some unexplored modifications on the indole scaffold are proposed. In particular, for the first time, substitutions at the C5 and N1 positions have been designed to give 48 compounds, which were synthesized and tested against norA-overexpressing S. aureus. Among them, 4 compounds have NorA IC50 values lower than 5.0 μM proving to be good efflux pump inhibitor (EPI) candidates. In addition, preliminary data on their ADME (absorption, distribution, metabolism, and excretion) profile is reported.

Publication types

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

MeSH terms

  • Anti-Bacterial Agents / chemistry*
  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Proteins / antagonists & inhibitors*
  • Dose-Response Relationship, Drug
  • Drug Resistance, Microbial / drug effects*
  • Indoles / chemistry*
  • Indoles / pharmacology*
  • Methicillin-Resistant Staphylococcus aureus / drug effects*
  • Molecular Structure
  • Multidrug Resistance-Associated Proteins / antagonists & inhibitors*
  • Structure-Activity Relationship

Substances

  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Indoles
  • Multidrug Resistance-Associated Proteins
  • NorA protein, Staphylococcus