Synthesis and Characterization of New Palladium(II) Complexes with Ligands Derived from Furan-2-carbaldehyde and Benzaldehyde Thiosemicarbazone and their in vitro Cytotoxic Activities against Various Human Tumor Cell Lines

摘要

With the ligands 4-phenyl-1-(furan-2-carbaldehyde)thiosemicarbazone, HTSC1, (1), 4-phenyl-1-(5 -phenyl-furan-2 carbaldehyde)thiosemicarbazone, HTSC2 (2), o-methoxy benzaldehydethiosemicarbazone, HTSC3 (3), and o-cyano-benzaldehydethiosemicarbazone, HTSC4 (4), the correspondingpalladium(II) complexes, Pd(TSC1)2 (5), Pd(TSC2)2 (6), Pd(TSC3)2 (7), and Pd(TSC4)2 (8) were synthesized and characterized by elemental analysis and spectroscopic techniques. The crystal structureof Pd(TSC3)2 (7) was determined by single-crystal X-ray diffraction. Complex 7 shows a squareplanar geometry, where two deprotonated ligands are coordinated to the PdII center through the nitrogenand sulfur atoms in a trans arrangement. In vitro antitumor studies against different human tumor cell lines have revealed that the palladium(II) complexes 5– 8 are more cytotoxic (IC50 valuesin the range of 0.21 – 3.79 µM) than their corresponding ligands (1 – 4) (> 60 µM). These results indicate that the antiproliferative activity is enhanced when thiosemicarbazone ligands are coordinatedto the metal. Among the studied palladium(II) complexes, 8 exhibits high antitumor activity on K562 chronic myelogenous leukemia cells with a low value of the inhibitory concentration (IC50 =0.21 µM).