Palladium(II) Chelates as Biologically Active Metallo-Drugs: Synthesis, Characterization, DNA Binding, Electrochemical and In Vitro Cytotoxic Studies

With the purpose of studying the binding behavior of Pd(II) complexes with DNA as the main biological target, and their ability to penetrate reasonably into tumor cells and destroy their replication ability, in this study, four new complexes [Pd(en)sar] (4) (where (TAB) is 3,4,3 ,4 -tetraaminobiphenyl hydrochloride; (en) is ethylenediamine; (meth) is methionine; (sar) is sarcosine) have been synthesized and characterized by conventional physicochemical analysis.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 8.36 10 3 M -1 and 4.25 10 3 M -1 for complexes (1) and (2), respectively.Thermal denaturation has been systematically studied by spectrophotometric method and the calculated T 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 the presence and absence of CT-DNA, show a quasi-reversible wave.The changes in E 1/2 , E and I pc /I pa ascertain the interaction of complexes with CT-DNA.In addition, the antitumor activity of the complexes was tested on two cancer cell lines: the colon cancer cell line (HCT) and breast cancer cell line (MCF-7), as well as one normal cell line: the human normal melanocytes (HFB4).The results showed that complex (1) was a more potent antitumor agent than complex (2).The in vitro antimicrobial activity of the complexes was carried out using the disc diffusion method against different species of pathogenic bacteria and fungi.The activity data showed the all complexes are highly reactive in inhibiting the growth of the tested organisms.