Impact of Cu2 + ions on the structure of colistin and cell-free system nucleic acid degradation

•Processes of colistin coordination to Cu2 + ions were described.•In oxidative stress conditions the DNA destruction was significant.•The complex shows higher oxidative properties than ligand and Cu2 +.•Generation of hydroxyl radical in the Cu2 +–colistin–H2O2 system was identified.•Degradation of RNA molecules by colistin was determined.

Colistin and transition metal ions are commonly used as feed additives for livestock animals. This work presents the results of an analysis of combined potentiometric and spectroscopic (UV–vis, EPR, CD, NMR) data which lead to conclude that colistin is able to effectively chelate copper(II) ions. In cell-free system the oxidative activity of the complex manifests itself in the plasmid DNA destruction with simultaneous generation of reactive OH species, when accompanied by hydrogen peroxide or ascorbic acid. The degradation of RNA occurs most likely via a hydrolytic mechanism not only for complexed compound but also colistin alone. Therefore, huge amounts of the used antibiotic for nontherapeutic purposes might have a potential influence on livestock health.

Graphical abstractThe coordination of copper(II) ions by colistin molecule was studied. It was shown that an antibiotic alone is able to cleave RNA molecules. When both colistin and its complex were used in the oxidative stress conditions also the degradation of plasmid DNA was very efficient.Figure optionsDownload full-size imageDownload as PowerPoint slide