Targeting CT-DNA with Novel Dafone–Pd(II) Complexes: In Vitro Cytotoxicity, In Vivo Efficacy, and Computational Insight

The novel complexes [Pd(bpy)(daf)](NO3)2 (1) and [Pd(daf)(dpa)](NO3)2 (2) (where bpy is 2,2’-bipyridine, daf is 4,5-diazaflourene-9-one (dafone), and dpa is 2,2’-dipyridylamine) were synthesized and studied using various methods. The cytotoxic effects of these complexes were investigated on two different cell types, colon cancer cells and NIH/3T3 fibroblasts, and compared with those of cisplatin. In vivo experiments did not show acute hepatorenal toxicity. Various spectroscopic, viscosity, and computational methods were employed to characterize the CT-DNA binding profile of the complexes. The experimental and theoretical results are mutually supportive and show that the complexes interact effectively with CT-DNA. According to the absorption study, the complexes interact with CT-DNA predominantly via a groove binding mode. The fluorescence spectroscopy data suggest static quenching as the underlying mechanism for the fluorescence quenching of the DNA system. The complexes primarily interact with CT-DNA via hydrogen bonding and van der Waals forces.