A new mononuclear zinc(II) complex: Crystal structure, DNA- and BSA-binding, and molecular modeling; in vitro cytotoxicity of the Zn(II) complex and its nanocomplex.

A new mononuclear Zn(II) complex, [Zn(Me2bpy)3](PF6)2·DMF (Me2bpy = 4,4'-dimethyl-2,2'-bipyridine), has been synthesized and fully characterized. Binding studies of the Zn(II) complex with fish sperm DNA (FS-DNA) and bovine serum albumine (BSA) were investigated using cyclic voltammetry, UV-Vis and fluorescence spectroscopies. The results showed that the majority of the interaction modes between the Zn(II) complex and DNA is a combination of the electrostatic and minor groove bindings, and the microenvironment of three aromatic amino acids residues is changed due to the interaction of the Zn(II) complex with BSA. In vitro cytotoxicity studies of the Zn(II) complex and its nanocomplex against three human carcinoma cell lines (MCF-7, A-549, and HT-29) using an MTT assay indicated that the cytotoxicity of both compounds against HT-29 and MCF-7 is higher than A-549. Moreover, the results clearly demonstrated that the aqueous colloid of the Zn(II) nanocomplex is more effective than the complex solution against HT-29 and MCF-7 cells under the same experimental conditions. The microscopic analyses of the cancer cells showed that the Zn(II) complex apparently induces the cell apoptosis. The interactions of the Zn(II) complex with DNA and BSA were also modeled using molecular docking. The results are in good agreement with the experimental findings.