Synthesis, Characterization, DNA Binding, Cleavage, Antibacterial, In vitro Anticancer and Molecular Docking Studies of Ni(II), Cu(II) and Zn(II) Complexes of 3,4,5-Trimethoxy-N-(3-Hydroxy-5-(Hydroxymethyl)-2-Methylpyridin-4-yl)methylene)Benzohydrazide

Abstract

The Schiff base ligand (L), 3,4,5-Trimethoxy-N-((3-hydroxy-5-(hydroxymethyl)-2-methylpyridin-4-yl)methylene)benzohydrazide (PLTMBH) was prepared by condensation of pyridoxal and 3,4,5-Trimethoxybenzohydrazide. The metal complexes of the ligand with Ni(II), Cu(II) and Zn(II) ions (M) were synthesized. The complexes were characterized by various spectroscopic IR, 1H-NMR, UV, LC–MS and ESR studies and analytical methods as elemental analysis, thermal analysis, molar conductance and magnetic susceptibility measurements. Based on the results, the complexes were assigned distorted octahedral geometry with a metal-to-ligand ratio, 1:2 (ML2). The interaction of the metal complexes with calf thymus (CT) DNA was investigated by electronic absorption and fluorescence emission spectra, viscosity measurements and molecular docking studies. The electronic and fluorescence spectra indicated that the metal complexes can bind to DNA with binding constant (Kb) of 0.819 × 104, 1.014 × 104and 0.427 × 104 M−1 for Ni(II), Cu(II) and Zn(II) complexes, respectively. The viscosity studies suggested groove mode of binding of the complexes with CT DNA. The docking studies of metal complexes with DNA were performed to assess possible mode of interaction, which also supported groove mode of binding for all the complexes. The complexes also showed significant cleavage ability of plasmid pBR322 DNA. The metal complexes showed good antibacterial activity, while the ligand showed moderate activity. The in vitro anticancer assay for the Ni(II) and Cu(II) complexes was performed by standard MTT assay method, against HeLa-Human cervical carcinoma cells, MCF-7-Human breast carcinoma cells and A549-Human lung carcinoma cells. The study indicated appreciable anticancer activity of the complexes.