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

• Published in: Journal of inorganic biochemistry Vol. 99; no. 3; pp. 698 - 706
• Main Authors: Rebolledo, Anayive P., Vieites, Marisol, Gambino, Dinorah, Piro, Oscar E., Castellano, Eduardo E., Zani, Carlos L., Souza-Fagundes, Elaine M., Teixeira, Letícia R., Batista, Alzir A., Beraldo, Heloisa
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.03.2005
• Subjects: Antineoplastic Agents - chemical synthesis; Antineoplastic Agents - pharmacology; Apoptosis - drug effects; Binding Sites; Cations - chemistry; Cell Cycle - drug effects; Cell Line, Tumor; Cytotoxic activity; Drug Screening Assays, Antitumor; Humans; Ligands; Metals - chemistry; Molecular Structure; Nitrogen - chemistry; Organometallic Compounds - chemical synthesis; Organometallic Compounds - pharmacology; Palladium - chemistry; Palladium complexes; Pyridines - chemistry; Spectrum Analysis; Structural studies; Thiosemicarbazones; Thiosemicarbazones - chemical synthesis; Thiosemicarbazones - metabolism; Thiosemicarbazones - pharmacology; Structural studies; Thiosemicarbazones; Palladium complexes; Cytotoxic activity
• ISSN: 0162-0134; 1873-3344
• DOI: 10.1016/j.jinorgbio.2004.11.022

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 P2 1/ c with a = 11.671(1), b = 10.405(1), c = 13.124(1), β = 115.60(1)° and Z = 4; [Pd(2Bz4M)Cl] ( 2) in the monoclinic space group P2 1/ c with a = 9.695(1), b = 15.044(1), c = 10.718(1) Å, β = 105.38(1)° 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) Å, α = 70.25(1), β = 73.46(1), γ = 83.57(1)° 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 GI 50 and LC 50 than the complexes, H2Bz4Ph being the most active with GI 50 < 0.003 μM; LC 50 = 13.4 μM; GI 50 = 9.3 μM, LC 50 = 12.9 μM; GI 50 < 0.003, LC 50 = 13.8 μM in the MCF-7, TK-10 and UACC-62 cell lines, respectively. Among the complexes, [Pd(2Bz4Ph)Cl] ( 3) exhibited the lowest values of GI 50 in the three studied cell lines.