Copper(Ii) Complexes With Tridentate Halogen-Substituted Schiff Base Ligands: Synthesis, Crystal Structures and Investigating the Effect of Halogenation, Leaving Groups and Ligand Flexibility on Antiproliferative Activities Publisher Pubmed



Kordestani N¹ ; Amiri Rudbari H¹ ; Fernandes AR² ; Raposo LR² ; Luz A² ; Baptista PV² ; Bruno G³ ; Scopelliti R⁴ ; Fateminia Z¹ ; Micale N³ ; Tumanov N⁵ ; Wouters J⁵ ; Abbasi Kajani A⁶ ; Bordbar AK^{1, 7}
Source: Dalton Transactions Published:2021

Abstract

To investigate the effect of different halogen substituents and leaving groups and the flexibility of ligands on the anticancer activity of copper complexes, sixteen copper(ii) complexes with eight different tridentate Schiff-base ligands containing pyridine and 3,5-halogen-substituted phenol moieties were synthesized and characterized by spectroscopic methods. Four of these complexes were also characterized by X-ray crystallography. The cytotoxicity of the complexes was determined in three different tumor cell lines (i.e.the A2780 ovarian, HCT116 colorectal and MCF7 breast cancer cell line) and in a normal primary fibroblast cell line. Complexes were demonstrated to induce a higher loss of cell viability in the ovarian carcinoma cell line (A2780) with respect to the other two tumor cell lines, and therefore the biological mechanisms underlying this loss of viability were further investigated. Complexes with ligandL1(containing a 2-pycolylamine-type motif) were more cytotoxic than complexes withL2(containing a 2-(2-pyridyl)ethylamine-type motif). The loss of cell viability in A2780 tumor cells was observed in the orderCu(Cl2-L1)NO3>Cu(Cl2-L1)Cl>Cu(Br2-L1)Cl>Cu(BrCl-L1)Cl. All complexes were able to induce reactive oxygen species (ROS) that could be related to the loss of cell viability. ComplexesCu(BrCl-L1)ClandCu(Cl2-L1)NO3were able to promote A2780 cell apoptosis and autophagy and for complexCu(BrCl-L1)Clthe increase in apoptosis was due to the intrinsic pathway.Cu(Cl2-L1)ClandCu(Br2-L1)Clcomplexes lead to cellular detachment allowing to correlate with the results of loss of cell viability. Despite the ability of theCu(BrCl-L1)Clcomplex to induce programmed cell death in A2780 cells, its therapeutic window turned out to be low making theCu(Cl2-L1)NO3complex the most promising candidate for additional biological applications. © The Royal Society of Chemistry 2021.