Cytotoxic Cu(II) Complexes with a Novel Quinoline Derivative Ligand: Synthesis, Molecular Docking, and Biological Activity Analysis.

The utilization of metallodrugs as a viable alternative to organic molecules has gained significant attention in modern medicine. We hereby report synthesis of new imine quinoline ligand ()-based Cu(II) complexes and evaluation of their potential biological applications. Syntheses of the ligand and complexes were achieved by condensation of 7-chloro-2-hydroxyquinoline-3-carbaldehyde and 2,2'-thiodianiline, followed by complexation with Cu(II) metal ions. The synthesized ligand and complexes were characterized using UV-vis spectroscopy, TGA/DTA, FTIR spectroscopy, H and C NMR spectroscopy, and pXRD. The pXRD diffractogram analysis revealed that the synthesized ligand and its complexes were polycrystalline systems, with nanolevel average crystallite sizes of 13.28, 31.47, and 11.57 nm for , , and , respectively. The molar conductivity confirmed the nonelectrolyte nature of the Cu(II) complexes. The biological activity of the synthesized ligand and its Cu(II) complexes was evaluated with assays, to examine anticancer activity against the human breast cancer cell line and antibacterial activity against Gram-positive () and Gram-negative ( and ) bacterial strains. The complex had the highest cytotoxic potency against breast cancer cells, with an IC of 43.82 ± 2.351 μg/mL. At 100 μg/mL, induced the largest reduction of cancer cell proliferation by 97%, whereas reduced cell proliferation by 53% and by 28%. The minimum inhibitory concentration for was found to be 12.5 μg/mL against the three tested pathogens. Evaluation of antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl revealed that exhibited the highest antioxidant activity with IC of 153.3 ± 1.02 μg/mL. Molecular docking results showed strong binding affinities of to active sites of , , and , indicating its high biological activity compared to and .