Systematical investigation of binding interaction between novel ruthenium(II) arene complex with curcumin analogs and ctDNA.

In this study, the interaction between a novel ruthenium(II) arene complex with curcumin analogs and calf thymus DNA (ctDNA) was investigated systematically by viscosity measurement, the DNA melting approach, multispectroscopic techniques and electrochemical methods. The absorption spectra of the ctDNA-drug complex showed a slight red shift and a weak hypochromic effect. The relative viscosity and melting temperature of ctDNA increased on addition of the drug. The evidence obtained from fluorescence competitive experiments indicated that the binding mode of the drug with ctDNA was intercalative. Using acridine orange (AO) as a fluorescence probe, the drug statically quenched the fluorescence of the ctDNA-AO complex, and hydrogen bonding and van der Waals interactions played vital roles in the binding interaction between the drug and ctDNA. The influences of ionic strength, chemical denaturants and pH on the binding interaction were also investigated. Circular dichroism and Fourier transform infrared spectra suggested that this drug might bond with the G-C base pairs of ctDNA and the right-handed B-form helicity of ctDNA remained after drug binding. The intercalative binding between the drug and ctDNA was further investigated using electrochemical techniques. All these results suggested that the biological activity of ctDNA was affected by ruthenium(II) arene complex with curcumin analogs.