Fluorophore Tagged Mixed Ligand Copper(II) Complexes: Synthesis, Structural Characterization, Protein Binding, DNA Cleavage and Anticancer Activity

Two fluorophore tagged copper(II) complexes [Cu(phen)(L)(ClO4)(2)] (1) and [Cu(bpy)(L)(H2O)(ClO4)](ClO4) (2), (where L=2-amino-1H-benzo[de]isoquinoline-1,3-(2H)dione (L), phen=1,10-phenanthroline and bpy=2,2 '-bipyridine) have been synthesized and structurally characterized. Structures of the copper complexes 1 and 2 were confirmed by single-crystal X-ray structure determination. The coordination geometry around the copper center of complexes 1 and 2 is distorted octahedral. The plasmid DNA cleavage activity of the complexes has been investigated by agarose gel electrophoresis and the study reveals that both the complexes have high plasmid DNA photo-cleavage activity. The binding interaction ability of the metal complexes with bovine serum albumin (BSA) was investigated using fluorescence spectroscopy. The cytotoxicity of the complexes has been evaluated by MTT (3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide) assay against A549 (adenocarcinoma human alveolar basal epithelial cells) and MCF-7 (breast cancer cell line) cell lines in comparison with cis-platin. Complexes 1 and 2 have exhibited better cytotoxic activity than cis-platin against A549 and MCF-7 cell lines. The cellular uptake study and localization of the complexes within the cells have been investigated by fluorescence microscopy. The cell staining and flow cytometry experiments suggest that complexes induce an apoptotic mode of cell death.