Palladium(II) complexes of 2-benzoylpyridine-derived thiosemicarbazones: spectral characterization, structural studies and cytotoxic activity

A. PEREZ REBOLLEDO; M. VIEITES; D. GAMBINO; OSCAR ENRIQUE PIRO; CASTELLANO, EE; C.L.ZANI; L.R.S. TEXEIRA; A.A. BATISTA; H. BERALDO

Journal of Inorganic Biochemistry

Elsevier

Año: 2005 vol. 99 p. 698 - 706

0162-0134

Palladium(II) complexes of 2-benzoylpyridine thiosemicarbazone (H2Bz4DH) and its N(4)-methyl (H2Bz4M) and N(4)-phenyl (H2Bz4Ph) derivatives were obtained and fully characterized. [Pd(2Bz4DH)Cl] (1) crystallizes in the monoclinic space group P21/c with a=11.671(1), b=10.405(1), c=13.124(1) A, beta=115.60(1)º and Z=4; [Pd(2Bz4M)Cl] (2) in the monoclinic space group P21/c with a= 9.695(1), b=15.044(1), c=10.718(1) A, beta=105.38(1)º, and Z=4 and [Pd(2Bz4Ph)Cl] (3) in the triclinic space group P-1 with a=9.389(1), b=13.629(1), c=15.218(1) A, alpha=70.25(1), beta=73.46(1), gamma=83.57(1)º, and two independent molecules per asymmetric unit (Z=4). All complexes show a quite similar planar fourfold environment around palladium(II). A negatively charged organic molecule acts as a tridentate ligand and binds to the metal through the pyridine nitrogen, the imine nitrogen and the sulfur atom. A chloride ion occupies the fourth coordination site. The planar complexes stack nearly parallel to one another in the lattice conforming a layered crystal structure. The cytotoxic activity of the thiosemicarbazones and their metal complexes was tested against the MCF-7, TK-10 and UACC-62 human tumor cell lines. The ligands exhibit lower values of GI50 and LC50 than the complexes, H2Bz4Ph being the most active with GI50 < 0.003 microM; LC50 = 13.4 microM; GI50 = 9.3 microM, LC50 = 12.9 microM; GI50 < 0.003, LC50 = 13.8 microM in the MCF-7, TK-10 and UACC-62 cell lines, respectively. Among the complexes, [Pd(2Bz4Ph)Cl] (3) exhibited the lowest values of GI50 in the three studied cell lines.