Comparable Investigation Of Binding Interactions Between Three Arene Ruthenium(Ii) Thiosemicarbazone Complexes And Calf Thymus Dna

Arene ruthenium(II) thiosemicarbazone complexes with different structures have received considerable attention in biomedical research. In order to reveal deeper structural influences on their biological func-tions, the binding interactions between three arene ruthenium(II) thiosemicarbazone complexes and calf thymus DNA (ctDNA) were comparably investigated by viscosity measurements and multi-spectroscopic techniques. Weak hypochromic effects were determined from the absorption spectra of the three ctDNA- compound systems. The raised melting temperature and the decreased relative viscosity of ctDNA were ascribed to the presence of these compounds. These compounds intercalated into the double helical structure of ctDNA through hydrogen bonding and van der Waals interactions. The right-handed B-form helicity of ctDNA remained unchanged after the addition of these compounds. The number of arene ruthenium(II) groups and the space steric hindrance of these compounds were responsible for the differences in the fluorescence quenching and the intercalative binding interactions. Compound C, with two arene ruthenium(II) groups and less steric hindrance, exhibited the strongest binding ability with ctDNA. These results provide a molecular understanding of the intercalative binding interactions between DNA and arene ruthenium(II) thiosemicarbazone complexes, which gives a new insight for the biological applications of arene ruthenium(II) complexes in the future. (c) 2020 Elsevier Ltd. All rights reserved.