Potent saccharinate-containing palladium(II) complexes for sensitization to cancer therapy

Abstract

Palladium(II) (PdII) complexes are among the most promising anticancer compounds. Both 2`-benzoylpyridine thiosemicarbazone (BpT) and saccharinate (Sac) are efficient metal chelators with potent anticancer activity. To explore a more effective new anticancer drug, we synthesized a series of Sac and BpT-containing PdII complexes coordinated with thiosemicarbazone (TSC)-derived ligands, and characterized them through nuclear magnetic resonance (NMR), Fourier transformed infrared spectroscopy (FT-IR), elemental analysis, ultraviolet-visible spectroscopy (UV–Vis) and thermogravimetric analysis (TGA). Each target complex was composed of PdII, BpT, and one or two Sac molecules. Both the in vitro and in vivo anti-growth effects of those ligands and the obtained PdII complexes were investigated in the human lung adenocarcinoma cell lines A549 and Spc-A1. The coordination of PdII with the TSC-derivatives and Sac resulted in clearly greater anticancer activity than single ligands. These compounds were demonstrated to be safe for 293 T normal human kidney epithelial cells. The introduction of Sac into the TSC-derived PdII complex significantly enhanced anti-growth effects, and induced apoptosis of human lung cancer cells in vitro and in vivo in a dose dependent manner. Moreover, the PdII complex containing two Sac molecules showed the most promising therapeutic effects, thereby confirming that Sac increases the cancer therapeutic efficacy of PdII complexes and providing a new strategy for exploring anticancer drugs for potential clinical treatment.