Structural characterisation of novel mononuclear Schiff base metal complexes, DFT calculations, molecular docking studies, free radical scavenging, DNA binding evaluation and cytotoxic activity

New mononuclear metal complexes (M = Mn(II), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II)) derived from a novel tetradentate N2O2 Schiff base ligand (H2L) were efficiently produced. Physico-chemical and spectroscopic approaches were used to characterize the synthesized metal complexes. The data indicated that the synthesized Schiff base acted as a tetradentate ligand and linked to various metal ions through the imine group's nitrogen and the phenolate oxygen. The capability of the produced complexes to bind CT-DNA using absorbance, fluorescence, viscosity and thermal denaturation assays along with DPPH radical scavenging was evaluated. The results revealed that both Mn(II) and Cu(II) complexes have a higher binding affinity and antioxidant activity when compared with other complexes. In vitro anti-proliferative activity of the new complexes using MTT assay was also performed against tumor cell lines HepG-2 and MCF-7. The results showed good activity on comparing with the reference medication cisplatin. Molecular geometry of metal complexes was examined using density functional theory (DFT) simulations. In addition, the DNA-interaction studies of complexes were validated by molecular docking experiments using molecular operating environment (MOE) software.

Automated summary

New mononuclear metal complexes derived from a tetradentate Schiff base ligand were successfully synthesized and characterized. The complexes exhibited strong binding affinity and antioxidant activity, particularly for Mn(II) and Cu(II) complexes. In vitro cell experiments demonstrated that the complexes had good anti-proliferative activity against tumor cells. The molecular geometry and DNA-interaction of the complexes were investigated using computational simulations and molecular docking experiments.