A Pd(II) complex derived from pyridine-2-carbaldehyde oxime ligand: Synthesis, characterization, DNA and BSA interaction studies and in vitro anticancer activity

Abstract

A novel Pd(II) complex, [Pd(C6H5N2O)2], containing pyridine-2-carbaldehyde oxime ligand has been synthesized and characterized using elemental analysis, Fourier-transform infrared, nuclear magnetic resonance and mass spectroscopy. The single crystal structure of this Pd(II) complex has been determined by X-ray crystallography. Based on the DNA binding studies including ultraviolet visible spectrophotometry, fluorescence emission titration and viscosity measurement, the interaction of Pd(II) complex with calf thymus DNA occurs by groove binding. In the absence of an external reductant, the Pd(II) complex cleaves the supercoiled double-stranded DNA under physiological conditions. Moreover, in the presence of Pd(II) complex, the Bovine Serum Albumin microenvironment and secondary structure change. On the basis of the competitive experiments using site markers, the complex is mainly located in site I of the protein. The binding of the Pd(II) complex to DNA was modeled using molecular docking. The antitumor impacts of the ligand and the Pd(II) complex were evaluated in vitro against the mouse colon carcinoma (C26) and melanoma (B16–F0) tumor cell lines. The antitumor activity has been significantly improved by the complexation process. IC50 values smaller than those of cisplatin have been shown by the Pd(II) complex and oxime ligand against cancer cell lines. In addition, Pd(II) complex has been tested against NIH normal fibroblast cells. Consequently, Pd(II) complex may be considered a selective compound against cancer cells, according to the SI definition.