title: Novel synthesis of palladium (II) complexes derived from 3-arylsydnone-4-carbaldehyde N(4)-phenylthiosemicarbazones and biological activity.
abstract: OBJECTIVE
  The aim of this research is to investigate whether the oxygen atom O(6) in the sydnone ring of 3-arylsydnone-4-carbaldehyde N(4)-phenylthiosemicarbazones (HArSYTSCs, 3a-d) is a good electron donor atom upon metal complexation. Furthermore, ligands 3a-d and the corresponding palladium complexes (Pd(ArSYTSC)Cl, 4a-d) would be expected to find their potent biological activities.
  
  
  METHODS
  The desired palladium complexes 4a-d were first synthesized from thiosemicarbazones 3a-d. Then, the antiproliferative activity of ligands 3a-d and complexes 4a-d were tested against human hepatocellular carcinoma and human cervical epithelioid carcinoma (HeLa) cells by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl trazolium bromide (MTT) assay.
  
  
  RESULTS
  According to X-ray analyses, ligands 3a-d are bonded to the Pd (II) center in an O, N, S-tridentate coordination mode through sydnone carbonyl oxygen O(6), azomethine nitrogen and the thiolate sulfur atom. The carbonyl oxygen of the sydnone ring is found to be a good electron donor site upon metal complexation. Moreover, MTT assay results reveal that the palladium complexes 4a-d have greater antiproliferative activity than 5-fluorouracil. In particular, the complexes exhibit obvious better activity than the corresponding ligands 3a-d against HeLa cell.
  
  
  CONCLUSIONS
  The results indicate that the synthesized novel palladium complexes have greater antiproliferative activity than both 5-fluorouracil and the corresponding ligands against HeLa cell. Accordingly, the study of sydnonyl complexes bearing anticancer activities may support the development of coordination chemistry.
authors.affiliation: Department of Chemical and Materials Engineering, Southern Taiwan University of Science and Technology, Tainan City, Taiwan.
authors.forename: Mei-Hsiu
authors.initials: MH
authors.lastname: Shih
authors.forename: Jian-Chyi
authors.initials: JC
authors.lastname: Chen
authors.forename: Guan-Ling
authors.initials: GL
authors.lastname: Lin
authors.forename: Tzu-Ting
authors.initials: TT
authors.lastname: Lin
authors.forename: Ming-Hsiang
authors.initials: MH
authors.lastname: Sun
mesh_terms: D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000494:pharmacology*; D006367:HeLa Cells; D056945:Hep G2 Cells; D006801:Humans; D008024:Ligands; D010165:Palladium / Q000737:chemistry* / Q000494:pharmacology*; D013882:Thiosemicarbazones / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D008024:Ligands; D013882:Thiosemicarbazones; D010165:Palladium
keywords: biological activity; palladium complexes; sydnones; thiosemicarbazides; thiosemicarbazones