Effects of Vitamin K3 on Cytotoxicity and DNA-binding Properties of a Palladium(II) Complex as a Potential Antitumor Agent

In many diseases such as cancer, simultaneous use of two or more pharmacologically active agents will be more effective and have fewer side effects. In this study a new palladium(II) complex with formula of [Pd(phen)(py-dtc)]NO3 (where is phen 1,10-phenanthroline and py-dtc is n-propyldithiocarbamate), was synthesized. The cytotoxic activity of this complex was tested against leukemia K562 cell lines. The cytotoxic concentration (Cc50) value of above Pd(II) complex was 53.06 μM. In the presence of vitamin K3, Cc50 value dramatically decreased to 32.95 μM and encouraged us to study DNA interaction of Pd(II) complex in the absence and presence of vitamin K3. Interaction of above Pd(II) complex in two modes (in the absence and presence of vitamin K3) with calf thymus DNA was evaluated using spectroscopic methods. UV-Vis results showed that in the presence of VK3, Pd(II) complex unexpectedly denatures CT-DNA at very low concentration. Fluorescence results showed that quenching of the intrinsic fluorescence of EBr-DNA system by Pd(II) complex is static quenching mechanism and type of mechanism does not change in the presence of vitamin. Also, in the absence and presence of vitamin, the mode of intercalation might play a major role in the interactions of Pd(II) complex with DNA. Several binding and thermodynamic parameters are also presented. We hope that these results provide a basis for additional studies and clinical use of combined anticancer drugs to be useful.