Two novel palladium(II)-amino acid complexes, [Pd(Ala)2]·H2O (PA) and [Pd(Val)2].H2O (PV) (Ala = alanine; Val = valine) were synthesized and characterized through FTIR, UV/Vis, 1H-NMR spectroscopies, CHN analysis, X-ray crystallography and molar conductivity measurement. Furthermore, cytotoxicity of Pd(II) complexes against human leukemia cancer cell line, MOLT4 showed promising cancer cell death (CC50 = 0.71 ± 0.046 µM for PA; CC50 = 0.85 ± 0.063 µM for PV) that were less than cisplatin (1.59 ± 0.25 µM). Moreover, the interaction of both the complexes with DNA and BSA was studied using UV-Vis absorption and emission spectroscopic techniques that demonstrated the bindings occurred via van der Waals forces and hydrogen bond. Furthermore, the fluorescence titration showed that static quenching mechanism plays predominate role in binding process. All results showed that both complexes have more binding tendency to DNA in compared to BSA that can be a significant achievement for further medical purposes as a potential antitumor candidate. Finally, molecular docking simulation was performed for PA and PV complexes with DNA and BSA and demonstrated both complexes bind to the groove of DNA mainly by hydrogen bond and interact with site I of BSA via hydrogen bond as well.
Keywords: Palladium(II) complex; amino acid; binding; cytotoxicity; mechanism; molecular docking; thermodynamic.