Structural parameters of the interaction between ciprofloxacin and human topoisomerase-II β enzyme: toward new 19F NMR chemical shift probes

Abstract

New tools for cancer diagnosis are being studied day by day, since early diagnosis can be crucial for a successful treatment. In this context, the use of NMR probes constitutes an efficient way of diagnosis. In this work, we investigated the use of ciprofloxacin to indirectly label the overexpression of topoisomerase-II enzymes by changes in 19F NMR chemical shifts of ciprofloxacin. Increased topoisomerase-II expression has been associated with cancer occurrence, mainly with aggressive forms of breast cancer, thus constituting a promising molecular targetfor new tumor cell identifiers. Using DFT calculations, a spectroscopy analysis of ciprofloxacin in different chemical environments, evaluating the solvent and enzymatic effects was performed. Our results point that the ciprofloxacin forms a stable complex with the enzyme, and the main intermolecular interactions between ciprofloxacin and human topoisomerase-IIβ are hydrogen bonds, following by pi-pi stacking and electrostatic interactions. Also, a shift of 6.04 ppm occurs in the 19F NMR signal when ciprofloxacin is interacting with the human topoisomerase-IIβ enzyme, and that this parameter may be a possible indirect marker to indicate the overexpression of these enzymes in the body.