1-N-substituted thiocarbamoyl-3-phenyl-2-pyrazolines: synthesis and in vitro antiamoebic activities.

The title compounds were prepared by reaction of Mannich bases with various N-4 substituted thiosemicarbazides. The chemical structures of the compounds were proved by means of their UV, IR, 1H NMR, 13C NMR spectroscopic data and elemental analyses. The in vitro antiamoebic activities of these compounds were evaluated by microdilution method against HM1:IMSS strain of Entamoeba histolytica and compared with the standard drug, metronidazole. It was concluded that 3-chloro and 3-bromo substituents on the phenyl ring at position 3 of the pyrazoline ring enhanced the antiamoebic activity. Compounds 9, 17, 18, 20 and 21 showed less IC50 value than metronidazole.