Synthesis and characterization of novel Schiff base ligand and their Cu (II), Zn (II), Co (II), and Ni (II) complexes: DNA binding, antimicrobial activity and docking studies

Abstract

In this paper, we describe the process of synthesizing and characterizing of cu (II), Ni (II), Co (II) and Zn (II) coordination compounds of 4,4'-((1E,1'E) -((4chloro-1,2phenylene) bis(azanylylidine)bis (methanylylidine)) bis (naphthalene-2-ol) [CAMD] Schiff base. Elemental analysis, molar conductance, spectral data (FT-IR, 1H NMR & 13C NMR, UV-visible, and mass spectra), and all the studies were used to establish their formation and validate their structures. All the complexes obtained as monomeric structure and the metal center moieties are fourcoordinated with square planar geometry, according to the spectral analysis. Herein, the calf thymus DNA (CT DNA) binding of complexes have been examined by UV-visible spectroscopy. All complexes interact with DNA through an intercalating way. In a series of dilution experiments with Kanamycin and Fluconazole as standards, the ligand and its metallic complexes (1-4) demonstrated antimicrobial activity against a variety of bacterial and fungal species, including Gram-positive (Staphylococcus aureus, Pseudomonas aeruginosa) and Gram-negative (Escherichia coli, Bacillus Subtilis, Salmonella Typhi), as well as fungal infections, and yeast infections. The preliminary in vitro antimicrobial screening revealed that the newly synthesised Schiff base inhibits bacterial and fungal growth significantly, compared to standard drugs. Additionally in silico studies of molecular docking were also done for Schiff base ligand and its multiplexes in the active site of DNA Gyrase enzyme (PDB code:6TCK), demonstrating strong hydrogen bonding interactions of drug targets and can be used as antibacterial drugs angainst pathogens. The performance of complexes closely matched the reactivity order seen in in-vitro studies. Overall, the complexes are intriguing candidates for antimicrobial development. We intend to use these compounds in a therapeutic context. Synthesized substances were determined to be non-toxic after undergoing ADME/T analysis to assess their drug-likeness.