Synthesis, characterization, DNA/BSA-binding affinity and biological activity of dinuclear palladium(II) complexes with aromatic N-heterocyclic bridging ligand

Abstract

Dinuclear palladium(II) complexes, [{Pd(en)Cl}2(μ-L)](NO3)2 (L is bridging ligand pirazine (Pd1), pyrimidine (Pd2), pyridazine (Pd3), phenazine (Pd4) and en is ethylenediamine), were synthesized and characterized. The interactions of the synthesized palladium(II) complexes with biomolecules such as DNA and BSA were studied using UV–Vis spectroscopy and fluorescence spectroscopy. Analysis of tumoricidal activity of investigated complexes, tested on several tumor cell lines of human and mouse origin, revealed that Pd1 and Pd2 exhibited weak cytotoxic potential at lower concentrations. However, Pd3 showed higher cytotoxicity effects on the human MDA-MB 468 breast carcinoma and A375 melanoma cell lines, while Pd4 exhibited tumoricidal potential against MDA-MB 468 cells and A549 human lung adenocarcinoma cells. Interestingly, A375 human melanoma cells were highly sensitive to Pd4 treatment similarly to the effect of cisplatin. Further, the antimicrobial effects of tested compounds were evaluated using different species of Gram-positive and Gram-negative bacteria, as well as yeasts. Pd1–Pd4 showed variable antimicrobial activity depending on the microorganism species. Among tested complexes, Pd4 exhibited the highest antimicrobial activity. The obtained data suggest that palladium(II) complexes might be further investigated as potential antitumor and antimicrobial agents.