Design, synthesis, and evaluation of fluorine and Naphthyridine-Based half-sandwich organoiridium/ruthenium complexes with bioimaging and anticancer activity

Abstract

A range of fluorine and naphthyridine-based half-sandwich iridium (III) and ruthenium (II) complexes were synthesized. The iridium complexes possessed excellent antiproliferative properties, a substantial improvement over cisplatin, especially the best 1C containing the fluorine atom and 2C containing the naphthyridine. On the contrary, the ruthenium complexes displayed much less antiproliferative activity. Two X-ray crystal structures were determined. The cytotoxicity of the complexes can be changed flexible by regulating the metal center and the ancillary ligands. The best complex 1C was chose to study further on the mechanism of action. The chemical reactivity such as hydrolysis, reaction with nucleobases, glutathione and catalytic conversion of NADH to NAD⁺, were investigated. Complex 1C can react with 9-ethylguanine (9-EtG) and catalyze oxidation of NADH. In addition, the self-luminescence of the complex 1C was also successfully used in confocal microscopy images for elucidating the subcellular localization. Complex 1C specifically targeted to lysosomes in A549 cancer cells and caused lysosomal damages and promote cathepsin B released. Flow cytometry studies confirmed that the biological effects of this type of complexes induced apoptosis, especially late apoptosis. Our results suggested that changes in the mitochondria membrane potential were responsible for apoptosis. The chemistry and biological studies has showed that this class of metal complexes are worthy of further exploration for the design of novel anticancer drugs.

Keywords: Anticancer; Apoptosis; Bioimaging; Iridium; Lysosomes targeted; Ruthenium.