Pd(II) complexes of 2,6-bis(1-ethyl-benzimidazol-2′-yl)pyridine and 4-((pyridin-2-ylmethylene)amino)aniline: antiproliferative properties and mechanism of action

In the present contribution, [PdClL¹]∙PF₆ (1) (L¹ = 2,6-bis(1-ethyl-benzimidazol-2´-yl)pyridine) and [PdCl₂L²] (2) (L² = 4-((pyridin-2-ylmethylene)amino)aniline) were synthesized, structurally characterized and evaluated for their potency against five cell lines of different origins. Computations using density functional theory were used to support the experimental research in order to better understand the character of the observed electronic absorption transitions and to look into how the coordinating ability of the associated ligands influences the metal center's natural charge, the strength of metal-ligand (M−L) bonds, and the type of hybridization. In contrast to 2, which was noncytotoxic to every cell line examined, complex 1 was twice as safe to Vero normal cells and shown approximately 2.5 times greater activity against MCF-7 cell line than cisplatin. The fluorescent-stain photos of MCF-7 cells treated with 1 revealed an increased presence of apoptotic bodies, indicating early apoptosis at 10 %, late apoptosis at 25 %, and a necrosis ratio of approximately 5 %. The flow cytometry results implied that 1 inhibited the cell cycle in MCF-7 cells in the G₂/M phase.