Organometallic ciprofloxacin conjugates with dual action: synthesis, characterization, and antimicrobial and cytotoxicity studies

Dalton Trans. 2020 Feb 7;49(5):1403-1415. doi: 10.1039/c9dt03948a. Epub 2019 Dec 18.

Abstract

The synthesis, characterization and biological activity of six bioorganometallic conjugates of ciprofloxacin with ferrocenyl, ruthenocenyl and cymantrenyl entities are described. Their antimicrobial activities were investigated against Gram-positive bacteria, Gram-negative bacteria and bloodstream forms of Trypanosoma brucei. Furthermore, the morphological changes of bacterial cells upon treatment with the conjugates were examined by scanning electron microscopy. In addition, the cytotoxicity of the conjugates against tumor and normal mammalian cells was also investigated. The results showed that conjugation of an organometallic moiety can significantly enhance the antimicrobial activity of the antibiotic ciprofloxacin drug. It was found that N-alkyl cymantrenyl and ruthenocenyl ciprofloxacin conjugates were the most effective derivatives although other conjugates also showed significant antimicrobial activity. The increase in the antimicrobial activity was most likely due to two independent mechanisms of action. The first mechanism is due to the bacterial topoisomerase inhibitory activity of ciprofloxacin while the second mechanism can be attributed to the generation of reactive oxygen species caused by the organometallic moiety. The presence of two modes of action enables the conjugates to kill bacteria in their stationary growth phase and to overcome the drug resistance of S. aureus strains. In addition, the conjugates showed promising selectivity toward bacterial and parasitic cells over mammalian cells.

MeSH terms

  • Animals
  • Anti-Bacterial Agents / chemical synthesis
  • Anti-Bacterial Agents / chemistry
  • Anti-Bacterial Agents / pharmacology*
  • Antineoplastic Agents / chemical synthesis
  • Antineoplastic Agents / chemistry
  • Antineoplastic Agents / pharmacology*
  • Cell Line
  • Cell Proliferation / drug effects
  • Cell Survival / drug effects
  • Ciprofloxacin / chemistry
  • Ciprofloxacin / pharmacology*
  • Dose-Response Relationship, Drug
  • Drug Screening Assays, Antitumor
  • Gram-Negative Bacteria / drug effects*
  • Gram-Positive Bacteria / drug effects*
  • HeLa Cells
  • Humans
  • Mice
  • Microbial Sensitivity Tests
  • Molecular Structure
  • Organometallic Compounds / chemical synthesis
  • Organometallic Compounds / chemistry
  • Organometallic Compounds / pharmacology*
  • Structure-Activity Relationship

Substances

  • Anti-Bacterial Agents
  • Antineoplastic Agents
  • Organometallic Compounds
  • Ciprofloxacin