Synthesis, characterization and DNA interaction studies of a new platinum(II) complex containing caffeine and histidine ligands using instrumental and computational methods

Abstract

<div><p>A new Pt(II) complex, [Pt(Caff)(His)(Cl)] (Caff is Caffeine (3,7-dihydro-1,3,7-trimethyl-1H-purine-2,6-dione) and His is l-Histidine), was synthesized and characterized using different physicochemical methods. The interaction of this complex with calf thymus DNA (ct-DNA) was investigated by absorption, emission, circular dichroism (CD), and viscosity measurements and molecular docking techniques. The calculated binding constant, <i>K</i>_b, was 5.3 × 10³ M⁻¹. In fluorimetric studies, the enthalpy and entropy of the reaction between the complex and ct-DNA showed that the reaction is exothermic (∆<i>H</i> = −184.07 kJ mol⁻¹, ∆<i>S</i> = −551.97 J mol⁻¹ K⁻¹). CD spectra of DNA in the presence of different amounts of the complex showed little changes in both the negative and positive band intensities, which imply a non-intercalative mode between the DNA and the platinum complex. Furthermore, the study of molecular docking also indicated that the complex binds to DNA via a groove binding mode.</p></div