Novel Ni(II) Complexes as Minor Groove Binders: Crystal Structures, Biomolecular Interactions, Molecular Docking, and Biological Activities

A novel ternary Ni(II) complexes, [Ni(5Clsal-phe)(phen)(H₂O)] (1) and [Ni(5Clsal-phe)(bpy)(H₂O)]CH₃OH (2), (Schiff base derived from the condensation of L-phenylalanine and 5-chlorosalicylaldehyde, phen: 1,10-phenanthroline, bpy: 2,2′-bipyridine) has been synthesized. The structure of the complexes was clarified by CHN analysis, FTIR, electronic absorption spectroscopy, ESI-MS, and X-ray single crystal diffraction methods. In biological activity studies, the interactions of the complexes with calf thymus DNA (CT-DNA) were examined using fluorescence spectroscopy. The results show that the complexes could bind to CT-DNA via a minor groove mode. The interactions of the complexes with bovine serum albumin (BSA) were investigated using electronic absorption and fluorescence spectroscopy techniques, and the BSA quenching mechanism was found. The radical scavenging activity of the complexes was investigated in comparison with hederacolchiside, taxifoline, hederasaponin, arachidonoyl dopamine, and silychristin used as standard. Molecular docking simulations were employed to investigate the interactions between the complexes and biomolecules such as DNA and BSA. The results revealed that the complexes insert into DNA via the minor groove and bind to BSA at subdomains I and IIA. These interactions are facilitated by conventional hydrogen bonds, van der Waals forces, alkyl, and π-alkyl interactions.