Synthesis, characterization and structure optimization of a series of thiazolidinone derivatives as Entamoeba histolytica inhibitors

A series of thiazolidinone derivatives were synthesized by sodium acetate assisted cyclization of 1-isobutyl-3-phenylthiourea with chloroacetic acid followed by the piperidine facilitated substitution of the resulting thiazolidinone with different substituted aldehydes. The ethene and imine double bonds adopt (Z,Z) configuration as indicated by (1)H-(1)H COSY and 2D-NOESY (1)H NMR and further confirmed by the crystal structure studies. The in vitro antiamoebic activity of these compounds was evaluated against HM1:IMSS strain of Entamoeba histolytica. Eight compounds exhibited promising activity with IC(50) values (0.11-0.172 μM) lower than the standard drug metronidazole (IC(50) 1.64 μM). In vitro cytotoxicity results revealed low cytotoxic up to the concentration of 25 μM.