Antiproliferative and interaction studies of a synthesized palladium(II) complex with human hemoglobin

Previous reports have shown that Pd(II) complexes, as non-platinum complexes, are great anti-tumor agents against various cancer cells with reduced side effects compared to cis-platin. In this study, the biological activity of a synthesized Pd(II) complex (2-foran-2-yl, 1H-imidazo-[4,54], 1,10-phenanthroline palladium chloride [Pd (-FIP)(2)]) was investigated. The cytotoxicity and anti-proliferative properties of the complex was evaluated using the human leukemia I<562 cancer cell line. Additionally, structural changes in the human blood carrier protein hemoglobin (Hb) was studied in the presence and absence of the Pd(II) complex using various spectroscopic methods including fluorescence and circular dichroism (CD) at two temperatures of 25 and 37 degrees C. The results have shown that this complex has a significant inhibitory effect on K562 cells by inducing apoptotic cell death. Intrinsic fluorescence data have shown a reduction in Hb fluorescence intensity through the addition of Pd(II) complex. Fluorescence quenching method was used to derive the stoichiometry of binding, the values of binding constants and the corresponding thermodynamic parameters at the two temperatures. The resulting values of Delta H degrees, Delta S degrees, and Delta G degrees indicated that the process of Pd(II)-Hb complex formation was spontaneous in which hydrogen bonding and van der Waals interactions played major roles. Furthermore, CD spectra.showed that the regular secondary structure of Hb does not change significantly. Finally, these results suggest that the newly synthesized Pd(II) complex can bind to Hb without changing the secondary structure of the protein, which is important in providing insights into the side effects of newly synthesized drugs on their carriers. (C) 2017 Elsevier B.V. All rights reserved.