Influence of DMbetaCD on the Interaction of Copper(II) Complex of 6-Hydroxychromone-3-carbaldehyde-3-hydroxybenzoylhydrazine with ctDNA

Abstract

The interaction mechanism between a scarcely soluble copper(II) complex of Cu(II)-6-hydroxychromone-3carbaldehyde-(3'-hydroxy)benzoylhydrazone( CuCHz) in aqueous solution and its DM beta CD complex was studied in the presence of ctDNA through spectroscopy and thermodynamic methods. The thermodynamic results indicate that the binding process of the CuCHz-DM beta CD inclusion complex is a spontaneous process and the inclusion is enthalpy-driven. The binding constants of CuCHz and CuCHz-DM beta CD with ctDNA are 2.69 x 10(3) and 14.7 x 10(3) L mol(-1), respectively. The stoichiometry of the complex is 1:1, and the determined thermodynamic indicates that the process of binding is spontaneous and entropy-driven. A competitive binding titration with ethidium bromide revealed that CuCHz efficiently displaces EB from the EB-DNA system. In addition to the thermal denaturation experiments and docking studies, we can confirm that the mode of binding of this complex to ctDNA is intercalation mode. The presence of DM beta CD enhances the aqueous solubility of CuCHz; nevertheless, the cyclodextrin did not affect the interaction of CuCHz with ctDNA because the inclusion complex breaks down when it binds with ctDNA.