Organoplatinum(II) Complexes with 2-Acetylthiophene Thiosemicarbazone: Synthesis, Characterization, Crystal Structures, and in Vitro Antitumor Activity

Novel organoplatinum(II) complexes with 2-acetylthiophene thiosemicarbazone (ATTSC) were synthesized. The reaction of K2PtCl4 with ATTSC in 1:1 and 1:2 metal to ligand ratios yielded 1 [Pt-4(ATTSC-2H)(4)center dot 4DMF] and 2 [Pt(ATTSC-H)(ATTSC)Cl center dot 3CH(3)OH)]. The crystal structures of these platinum chelates have been solved by single-crystal Xray diffraction structure determinations and revealed metalation of the thiophene ring at C2 through platinum atoms. Further characterization of 1 and 2 was performed using electronic, IR, UV/vis, and NMR spectroscopies and elemental analysis. The in vitro antitumor activity of the ligand as well as 1 and 2 was determined against two different human tumor cell lines (HT-29 and HuTu-80). These tests revealed that the platinum(II) complexes are more cytotoxic than their ligand. The tetranuclear complex 1 shows higher antiproliferative activity (IC50 = 1.2 and 1.5 mu M) when compared to 2 (IC50 = 3 and 5.9 mu M), while the ligand has IC50 values of 8.6 and > 10 mu M. Compounds 1 and 2 can therefore be considered as agents with potential antitumor activity.