Design, synthesis and in vitro bioactivity of mixed ligand Ru(II) complexes bearing the fluoroquinolone antibacterial agents

Abstract

Mixed ligand Ru(II) phenanthroline complexes of the type [Ru(1,10-phen)2Flq]ClO4 (RPFlq-1-3) and “piano-stool”-type Ru(II) arene complexes [Ru(η6-p-cymene)Cl(Flq)] (RAFlq-1-3), where Flq = fluoroquinolone, have been synthesized, characterized and studied for their anticancer potential. DFT calculations were in line with the proposed structures, wherein the fluoroquinolones are coordinated to the metal through the ring carbonyl and one of the carboxylic oxygen atoms in a bidentate fashion. Binding efficacies of the synthesized complexes with bovine serum albumin (BSA) and CT-DNA were studied spectroscopically, and it has been established that the arene complexes, though have moderate binding propensities to CT-DNA (Kb = 0.8–1.7 × 103 M−1), have 102–103-fold better binding efficacies toward BSA (Ka = 3.2 × 105–2.1 × 106 M−1) due to the presence of the hydrophobic arene moiety. These results further prompted a study in their in vitro cytotoxicity assay on A-549 non-small cell lung cancer and MCF7 breast cancer cell lines. Furthermore, gene expression studies on BAX and BCL-2 genes and FACS analysis confirmed apoptosis as the mode of cell death.