Comparative study of two cephalosporin antibiotics binding to calf thymus DNA by multispectroscopy, electrochemistry,...

The over-use of antibiotics has caused a number of problems such as contamination of antibiotic residues and virus resistance, and therefore has attracted global attention. In this study, spectroscopic techniques and molecular docking were employed to predict conformational changes and binding interaction between two cephalosporins (cefaclor and cefixime) and calf thymus DNA (ctDNA). Fluorescence and UV-vis spectra suggested that static quenching was predominant and cephalosporin bound to the groove region of ctDNA. Binding parameters calculated by the Stern-Volmer and Scatchard equations showed that cephalosporin bound to ctDNA with a binding affinity in the order of 10³  L mol^-1 . Thermodynamic parameters further indicated that the reaction was a spontaneous process driven by enthalpy and entropy, and that the main binding force was an electrostatic force. The effects of iodide, denaturant, thermal denaturation and pH on a cephalosporin-Hoechst-DNA complex were also studied, and the results confirmed that cephalosporin bound to the groove area of DNA. Finally, these results were further confirmed by molecular docking and electrochemical studies.