Synthesis, Characterization, and Cytotoxic Activities of a Schiff Base Ligand and Its Binuclear Copper(II) and Manganese(III) Complexes

Abstract

A novel symmetrical N2O2 type Schiff base (1) and its copper (II) (2) andmanganese (III) (3) complexes were synthesized and characterized by spectroscopic,analytical, and magnetic susceptibility studies. Spectroscopic and magnetic susceptibilitystudies suggested that copper and manganese ions are in 2+ and 3+ states and theircomplexes have a binuclear double stranded helical structure in the form of 2:2 (metal toligand) stoichiometry. Cytotoxic effects of the ligand and its metal complexes against MCF7 (human breast cancer cell line), DLD-1 (human colorectal cancer cell line), ECC-1 (humanendometrium cancer cell line), DU-145 (human prostate cancer line), MDA-MB231 (humanbreast cancer cell line), PC-3 (human prostate cancer line) and HEK293 (normal cells) wereevaluated by determining their cellular viability using the colorimetric 3-(4,5-dimethylthiazole-2-yl)-2,5-biphenyl tetrazolium bromide (MTT) assay. It has been foundthat cytotoxicity of the ligand was significantly enhanced towards cancer cells and declinedtowards normal HEK293 cells by metal chelation. Copper complex yielded better results incomparison with manganese complex. Particularly, copper complex showed a selectivecytotoxicity, harming the cancerous cell lines while not impairing the normal cells, whichis considered as the key to the future of cytotoxic therapy.