Synthesis, characterization, biological activity and molecular docking study of transition metal complexes from heterocyclic ligand system

The bivalent metal chelates of manganese, cobalt, nickel, copper, and zinc have been synthesized from 3-acetylcoumarin derivative. The compounds were characterized using elemental analysis and spectral techniques such as molar conductance, IR, UV, magnetic moment, 1 H NMR, 13 C NMR, mass, EPR, and fluorescence studies. The ligand (IMAC) coordinates to the metal ion in tridentate binding mode through the amide carbonyl, azomethine nitrogen and lactone carbonyl oxygen of the coumarin moiety. All the complexes have octahedral geometry. XRD data revealed that the ligand is crystalline in nature and all the complexes are amorphous in nature. The DNA cleavage activities of the compounds have been studied using pUC18 plasmid DNA and the results showed moderate activity. The antifungal activities were examined by disc diffusion method. Cobalt(II), nickel(II), copper(II) and zinc(II) complexes displayed good activity when compared to the ligand and manganese(II) complex. The antibacterial activities have been evaluated against Staphylococcus aureus and Escherichia coli. The nickel(II) complex showed more pronounced activity than other compounds. The antioxidant activity of manganese, cobalt and zinc chelates exhibited excellent percentage of inhibition than the ligand. The in vitro anticancer activity is studied against human cancer cell lines such as Breast cancer cell (MCF-7) and Leukemia cancer cell (K-562) with standard drug adriamycin. The results showed moderate activity compared with standard drug. Furthermore, molecular docking of ligand and nickel(II) complex is investigated with CDK2 protein and concluded that nickel(II) complex has better binding affinity than ligand.