Macrocyclic Schiff Base Complexes of Zn(II), Cu(II), Co(II), and Ni(II) Targeting Topoisomerase IIβ: Synthesis, Docking, and Evaluation as Potential Anticancer Agents

This study explores the potential of newly synthesized macrocyclic Schiff base metal complexes containing Zn(II), Cu(II), Ni(II) and Co(II) ions as Topoisomerase II beta inhibitors. The complexes were derived from the condensation of 2,3-diamino-5-bromopyridine and 2,5-thiophenedicarboxaldehyde. Their formation was confirmed through various spectroscopic techniques. To gain insights into their structure and potential biological activity, computational modeling was employed. The density functional theory (DFT) was utilized to optimize the molecular geometries of the complexes. Furthermore, in silico docking simulations with the AutoDock Vina and GOLD scoring function investigated their binding interactions with Topoisomerase II beta, an enzyme critical for cancer cell proliferation. The combined computational analysis revealed promising binding affinities for all complexes, with complex 3b demonstrating the most favorable interaction with the target enzyme having binding energy -8.56 kcal/mol. To validate these in silico predictions, the cytotoxicity of the complexes was evaluated using the established MTT assay. The observed cytotoxicity results complemented the anticipated binding patterns, with Cu(II) complex 3b demonstrating the strongest inhibitory effect on cancer cells with IC50 value 0.04 mu M. Additionally, the hemolytic effect of the complexes on human red blood cells (hRBCs) was assessed to determine their biocompatibility. This strong correlation between predicted interactions, observed cytotoxicity, and minimal hemolytic effect highlights the potential of these complexes, particularly 3b, as promising leads for developing novel anticancer drugs targeting Topoisomerase II beta. Future research will focus on elucidating the detailed mechanism of action of these complexes and exploring their broader pharmacological profile.