Synthesis and antiamoebic activity of new 1-N-substituted thiocarbamoyl-3,5-diphenyl-2-pyrazoline derivatives and their Pd(II) complexes.

Some 1-N-substituted thiocarbamoyl-3,5-diphenyl-2-pyrazoline derivatives (L), 1-8 were synthesized by a base-catalyzed Claisen-Schmidt condensation of benzaldehyde with acetophenone followed by cyclization with various N-4 substituted thiosemicarbazides. The palladium(II) complexes [PdLCl2], 1a-8a of these ligands were obtained by reacting them with [Pd(DMSO)2Cl2]. All compounds have been characterized by means of elemental analyses, electronic, IR, 1H NMR and mass spectroscopic data, while the complexes have additionally been characterized by thermogravimetric patterns. The in vitro antiamoebic activity was evaluated against the HM1:IMSS strain of Entamoeba histolytica and the results were compared with the standard drug, metronidazole. The preliminary test results showed that the complexes had better antiamoebic activity than their respective ligands. Moreover, the complexes showed better inhibition of the test organism. The results suggest that the ligands 4, 7 and the complexes 2a-4a, 6a-8a were found with IC50 lower than that of the standard drug metronidazole and thus are better inhibitor of growth of E. histolytica.