Mononuclear Pd(II) and Pt(II) complexes with an α-N-heterocyclic thiosemicarbazone: cytotoxicity, solution behaviour and interaction versus proven models from biological media

Two Pd(II) and Pt(II) complexes with two pyrrol-2-carbaldehyde N-p-chlorophenylthiosemicarbazone ligands are designed and characterized showing mononuclear structures. An important pharmacological property for both compounds is the high selectivity for tumor cells and a lack of activity in healthy cells. The Pd(II) compound shows a higher antitumor activity and selectivity than the Pt(II) compound. Both complexes present a variety of biological interactions: with DNA models (pBR322 and CT DNA), proteins (lysozyme and RNase) and other biological targets like proteosome. Our results show that the Pd(II) complex is a more interesting candidate for potential anticancer therapies than the Pt(II) complex, and we provide new insight into the design and synthesis of palladium compounds as potential antitumor agents.