DNA interaction studies of a platinum (II) complex containing an antiviral drug, ribavirin: The effect of metal on DNA binding

The water-soluble Pt (II) complex, [PtCl (DMSO)((NN7)-N-4- ribavirin)]. H2O (ribavirin is an antiviral drug) has been synthesized and characterized by physico-chemical and spectroscopic methods. The binding interactions of this complex with calf thymus DNA (CT-DNA) were investigated using fluorimetry, spectrophotometry, circular dichroism and viscosimetry. The complex binds to CT-DNA in an intercalative mode. The calculated binding constant, K-b, was 7.2 x 10(5) M-1. In fluorimetric studies, the enthalpy (Delta H < 0) and entropy (Delta S > 0) changes of the reaction between the Pt (II) complex with CT-DNA showed hydrophobic interaction. In addition, CD study showed stabilization of the right-handed B form of CT-DNA. All these results prove that the complex interacts with CT-DNA via intercalative mode of binding. In comparison with the previous study of the DNA interaction with ribavirin, these results show that platinum complex has greater affinity to CT-DNA. (C) 2012 Elsevier B.V. All rights reserved.