Cytotoxicity, CT-DNA/BSA interaction and antioxidant activity of Ni(II), Cu(II) and Zn(II) complexes derived from a design nematogenic L-Alanyl-glycine based Schiff base ligand

Abstract

A new mesogenic L-Alanyl-glycine peptide-based Schiff base ligand and its Ni(II), Cu(II), and Zn(II) complexes have been successfully synthesised and characterised through various spectroscopic techniques and elemental analysis. The anticancer potential of these peptide-based Schiff base complexes was assessed against the A-549 lung adenocarcinoma cell line, revealing that the NiL₂ complex exhibited the highest cytotoxic activity, surpassing that of the CuL₂ and ZnL₂ complexes. The in vitro interactions of these metal complexes with biomolecules, specifically CT-DNA and BSA, were analysed using photophysical techniques, demonstrating that the CuL₂ and ZnL₂ complexes exhibited the strongest binding affinity among the tested compounds. Additionally, their antioxidant activity was evaluated through a DPPH (1,1-diphenyl-2-picryl-hydrazyl) assay, wherein the Cu(II) complex emerged as the most effective free radical scavenger. Analysis of mesogenic properties indicated that, while the ligand itself exhibited nematic mesogenicity, its metal complexes were non-mesogenic. Furthermore, density functional theory (DFT) calculations were conducted to obtain the energy-optimized structures of the synthesised compounds, providing insights into their molecular stability and electronic properties.