Biomolecular docking interactions, cytotoxicity and antioxidant property evaluations with novel Mn(II), Ni(II), Cd(II) and Pb(II) Schiff base ligand complexes: Synthesis and characterization

The development of Schiff base-centered medical chemistry in conjunction with the use of less-expensive transition metals with high pharmacological activity has currently triggered enormous interest in the development of novel Schiff base ligands. In this context, four different metal complexes comprising Mn(II), Ni(II), Cd(II) and Pb(II) (labeled as complexes 1–4) were synthesized using a novel tetra-dentate ligand (L) obtained by condensation of 3,5-dichlorosalicylaldehyde and trans -1,2-diaminocyclohexane, as demonstrated herein. The physico-chemical properties of the complexes were evaluated through UV–Vis, FT-IR, NMR, TGA, powder XRD and ESI–MS analyses. The crystalline states of the metal complexes were analysed by powder XRD. The existence of the lattice as well as coordinated water molecules in the complexes were demonstrated by the thermal characteristics of the complexes. The thermal stability of all the compounds is due to their high melting points. Studies on the free radical scavenging and antibacterial properties performed with the ligand L and the synthesized metal complexes 1–4 revealed that the Ni(II) complex had higher efficiency. Also, their bactericidal properties were tested with gram-positive ( Staphylococcus aureus ) and gram-negative ( Escherichia coli ) bacteria. Using Ni(II) as a model, anticancer studies for MCF-7 breast cancer cell lines were performed. By using molecular docking studies, the interactions between drugs and biomolecules were identified. The Ni(II) complex showed synergistic activity, exemplifying its stronger anticancer action, establishing its higher inhibiting efficiency of 68.26% at 320 g/mL. The present investigation, therefore, acknowledges the viability of these newly synthesized Schiff base-derived complexes as clinical-trial prodrugs.