Crystal Structures and Biological Profiles of Novel Tridentate Schiff Bases Nickel (II) Complexes

Novel bioactive ternary nickel (II) complexes, [Ni(5BrSal-Phe)(phen)] (1) and [Ni(5BrSal-Tyr)(phen)] (2) (5BrSal-Tyr: Schiff base derived from 5-bromosalicylaldehyde and L-tyrosine, 5BrSal-Phe: Schiff base derived from 5-bromosalicylaldehyde and L-phenylalanine, phen: 1,10-phenanthroline), have been synthesized and characterized by electronic absorption spectroscopy, CHN, FTIR, ESI-MS and X-ray crystallography techniques. Interaction of the complexes with biomolecules (calf thymus DNA (CT-DNA) and bovine serum albumin (BSA)) has been investigated by electronic absorption and fluorescence spectroscopy. The results show that the complexes can bind to CT-DNA via a minor groove binding mode. Moreover, the fluorescence quenching mechanism between the complexes and BSA is a static quenching process. The antiproliferative activities of the complexes against breast cancer cells (MCF-7 and MDA-MB-231) and healthy breast epithelial cells (MCF-10A) were investigated. The complex 2 was found to have promising antiproliferative activity in selected cell line, with lower IC values than cisplatin. Molecular docking studies suggest that the complexes may serve as potential chemotherapeutic agents. These complexes have been observed to interact with various targets within cells, including the epidermal growth factor receptor (EGFR), bovine serum albumin (BSA), and B-DNA. Analyses indicate that these interactions are supported not only by conventional hydrogen bonds but also van der Waals forces and π-π interactions. Additionally, determining binding constants and regions enhances our understanding of how the complexes interact with target molecules. The results emphasize the importance of the complexes in cancer therapy by highlighting the necessity of understanding their molecular-level interactions with targets.