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

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.