Synthesis and structural characterization of ternary Cu (II) complexes of glycine with 2,2′-bipyridine and 2,2′-dipyridylamine. The DNA-binding studies and biological activity

Abstract: In this study two new complexes [Cu(bpy)(Gly)Cl]·2H2O (1) and [Cu(dpa)(Gly)Cl]·2H2O (2) (bpy=2,2′-bipyridine; dpa=2,2′-dipyridylamine, Gly=glycine) have been synthesized and characterized by elemental analysis, IR, TGA, UV–vis and magnetic susceptibility measurements. The binding properties of the complexes with CT-DNA were investigated by electronic absorption spectra. The intrinsic binding constants (K b) calculated from UV–vis absorption studies were 1.84×103 M−1 and 3.1×103 M−1 for complexes 1 and 2 respectively. Thermal denaturation has been systematically studied by spectrophotometric method and the calculated ΔT m was nearly 5°C for each complex. All the results suggest that the interaction modes between the complexes and CT-DNA were electrostatic and/or groove binding. The redox behavior of the two complexes was investigated by cyclic voltammetry. Both complexes, in presence and absence of CT-DNA show a quasi-reversible wave corresponding to CuII/CuI redox couple. The change in E 1/2, ΔE and I pc/I pa ascertain the interaction of complexes 1 and 2 with CT-DNA. Further insight into the binding of complexes with CT-DNA has been made by gel electrophoresis, where the binding of complexes is confirmed through decreasing the mobility and intensity of DNA bands. In addition, the antitumor activity of the complexes was tested on two cancer cell lines; the breast cancer (MCF7) and the human hepatocellular carcinoma (HEPG2), as well as one normal cell line; the human normal melanocytes (HFB4). The results showed that complex 1 was more potent antitumor agent than complex 2. The in-vitro antimicrobial activity of the two complexes was carried out using the disc diffusion method against different species of pathogenic bacteria and fungi. The activity data showed that complex 2 was more active in inhibiting the growth of the tested organisms. [Copyright &y& Elsevier]