Targeted Antibacterial Activity Guided by Bacteria-Specific Nitroreductase Catalytic Activation to Produce Ciprofloxacin

Bioconjug Chem. 2019 Mar 20;30(3):751-759. doi: 10.1021/acs.bioconjchem.8b00887. Epub 2019 Feb 22.

Abstract

Fluoroquinolones (FQs) are among the front-line antibiotics used to treat severe infections caused by Gram-negative bacteria. However, recently, due to toxicity concerns, their use has been severely restricted. Hence, efforts to direct delivery of this antibiotic specifically to bacteria/site of infection are underway. Here, we report a strategy that uses a bacterial enzyme for activation of a prodrug to generate the active antibiotic. The ciprofloxacin-latent fluorophore conjugate 1, which is designed as a substrate for nitroreductase (NTR), a bacterial enzyme, was synthesized. Upon activation by NTR, release of Ciprofloxacin (CIP) as well as a fluorescence reporter was observed. We provide evidence for the prodrug permeating bacteria to generate a fluorescent signal and we found no evidence for activation in mammalian cells supporting selectivity of activation within bacteria. As a testament to its efficacy, 1 was found to have potent bactericidal activity nearly identical to CIP and significantly reduced the bacterial burden in a neutropenic mouse thigh infection model, again, at comparable potency with CIP, a clinically used FQ. Thus, together, we have developed a small molecule that facilitates bacteria-specific fluoroquinolone delivery.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anti-Bacterial Agents / chemical synthesis*
  • Bacteria / drug effects*
  • Bacteria / enzymology
  • Catalysis
  • Ciprofloxacin / chemical synthesis*
  • Enzyme Activation
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Microbial Sensitivity Tests
  • Nitroreductases / metabolism*

Substances

  • Anti-Bacterial Agents
  • Ciprofloxacin
  • Nitroreductases