Modulation of catalytic and biomolecular binding properties of ruthenium(II)-arene complexes with the variation of coligands for selective toxicity against cancerous cells

Abstract

Four ruthenium(II)-arene complexes, viz. [Ru(p-cym)(2-ampy)Cl]PF6 1, [Ru(benzene)(2-ampy)Cl]SO3CF3 2, [Ru(p-cym)(2-ampy)PPh3](PF6)2 3 and [Ru(benzene)(2-ampy)PPh3](SO3CF3)2 4 [2-ampy = 2-aminomethyl pyridine] have been synthesized and characterized. Different analytical techniques have been utilized to characterize 1–4 and a DFT study was used to optimize the geometries and calculate the energies of the frontier molecular orbitals. An MTT assay revealed the potency of complexes 1–4 against MCF-7 (breast cancer) and Hela (cervical cancer) cell lines. The presence of the triphenyl phosphine ligand in complexes 3 and 4 makes the complexes more cytotoxic with respect to their chloro-analogues. The complexes are found to be specifically cytotoxic against cancerous cell lines only, as they were inactive against the normal HEK 293 cell line. An absorption and fluorescence titration study of complexes 1–4 showed significant interactions with DNA and proteins. Interestingly, all the complexes show potent catalytic activity for the hydrogen transfer of NADH and converted NADH to NAD+, which helps to induce the accumulation of intracellular reactive oxygen species (ROS) in MCF-7 cells. To analyze the morphological changes in the cells, the Hoechst staining method was applied to capture images of apoptotic cells through confocal microscopy. © 2021 Elsevier Ltd