New palladium(II) complexes of 5-nitrothiophene-2-carboxaldehyde thiosemicarbazones: Synthesis, spectral studies and in vitro anti-amoebic activity

Thiosemicarbazones (1-7) and their palladium(11) complexes (1a-7a) of the type [Pd(TSCN)Cl-2] (where TSCN = thiosemicarbazone) were prepared from 5-nitro thiophene-2-carboxaldehyde and [Pd(DMSO)(2)Cl-2], respectively. Coordination via the thionic sulphur and the azomethine nitrogen atom of the thiosemicarbazones to the metal ion were confirmed by spectral data. These compounds were screened in vitro against (HK-9) strain of Entamoeba histolytica possess amoebicidal properties. Enhancement of antiamoebic activity resulted due to the introduction of palladium metal in the thiosemicarbazone moiety. The most promising of the group tested are [Pd(5-N-2-TCA-COTSCN)Cl-2] and [Pd(5-N-2-TCA-AdmTSCN)Cl-2] comparable to that of metronidazole. (C) 2003 Elsevier Science Ltd. All rights reserved.