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

Abstract

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 [Pt4(ATTSC-2H)4·4DMF] and 2 [Pt(ATTSC-H)(ATTSC)Cl·3CH3OH)]. The crystal structures of these platinum chelates have been solved by single-crystal X-ray 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 μM) when compared to 2 (IC50 = 3 and 5.9 μM), while the ligand has IC50 values of 8.6 and >10 μM. Compounds 1 and 2 can ...