NOVEL COPPER-CONTAINING CYTOTOXIC AGENTS BASED ON 2-THIOXOIMIDAZOLONES.

A series of 73 ligands and 73 of their Cu+2 and Cu+1 copper complexes with different geometries, oxidation states of the metal, and redox activities were synthesized and characterized. The aim of the study was to establish the structure-activity relationship within a series of analogues with different substituents at the N(3) position, which govern the redox potentials of the Cu+2/Cu+1 redox couples, ROS generation ability, and intracellular accumulation. Possible cytotoxicity mechanisms, such as DNA damage, DNA intercalation, telomerase inhibition, and apoptosis induction have been investigated. ROS formation in MCF-7 cells and 3D spheroids was proven using Pt-nanoelectrode. Drug accumulation and ROS formation at 40-60 µm spheroid depths was found to be the key factor for the drug efficacy in the 3D tumor model, governed by the Cu+2/Cu+1 redox potential. A nontoxic in vivo single dose evaluation for two binuclear mixed-valence Cu+1/Cu+2 redox-active coordination compounds, 72k and 61k, was evaluated.