A Highly Potent Class of Halogenated Phenazine Antibacterial and Biofilm-Eradicating Agents Accessed Through a Modular Wohl-Aue Synthesis

Sci Rep. 2017 May 17;7(1):2003. doi: 10.1038/s41598-017-01045-3.

Abstract

Unlike individual, free-floating planktonic bacteria, biofilms are surface-attached communities of slow- or non-replicating bacteria encased within a protective extracellular polymeric matrix enabling persistent bacterial populations to tolerate high concentrations of antimicrobials. Our current antibacterial arsenal is composed of growth-inhibiting agents that target rapidly-dividing planktonic bacteria but not metabolically dormant biofilm cells. We report the first modular synthesis of a library of 20 halogenated phenazines (HP), utilizing the Wohl-Aue reaction, that targets both planktonic and biofilm cells. New HPs, including 6-substituted analogues, demonstrate potent antibacterial activities against MRSA, MRSE and VRE (MIC = 0.003-0.78 µM). HPs bind metal(II) cations and demonstrate interesting activity profiles when co-treated in a panel of metal(II) cations in MIC assays. HP 1 inhibited RNA and protein biosynthesis while not inhibiting DNA biosynthesis using 3H-radiolabeled precursors in macromolecular synthesis inhibition assays against MRSA. New HPs reported here demonstrate potent eradication activities (MBEC = 0.59-9.38 µM) against MRSA, MRSE and VRE biofilms while showing minimal red blood cell lysis or cytotoxicity against HeLa cells. PEG-carbonate HPs 24 and 25 were found to have potent antibacterial activities with significantly improved water solubility. HP small molecules could have a dramatic impact on persistent, biofilm-associated bacterial infection treatments.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / chemical synthesis*
  • Anti-Bacterial Agents / chemistry
  • Anti-Bacterial Agents / pharmacology*
  • Bacteria / drug effects
  • Biofilms / drug effects*
  • Cell Survival
  • Chemistry Techniques, Synthetic*
  • Halogenation
  • HeLa Cells
  • Humans
  • Methicillin-Resistant Staphylococcus aureus / drug effects
  • Microbial Sensitivity Tests
  • Phenazines / chemical synthesis*
  • Phenazines / chemistry
  • Phenazines / pharmacology*
  • Spectrophotometry, Ultraviolet
  • Structure-Activity Relationship

Substances

  • Anti-Bacterial Agents
  • Phenazines
  • phenazine