Synthesis of some 1,3,4-thiadiazole derivatives as inhibitors of Entamoeba histolytica

In the quest for potent anti-amoebic agents, some 1,3,4-thiadiazole derivatives were synthesized and characterized by spectral data. The purity of the compounds was confirmed by elemental analysis. All the compounds were screened in vitro against HM1:IMSS strain of Entamoeba histolytica by microdilution method. The results revealed that compounds 1 (IC₅₀ = 0.670 μM), 3 (IC₅₀ = 1.60 μM) and 8 (IC₅₀ = 0.522 μM) had much better anti-amoebic activity than the reference drug metronidazole (IC₅₀ = 1.80 μM). Further, cytotoxicity of the compounds having IC₅₀ value less than metronidazole was assessed by MTT assay on human breast cancer MCF-7 cell line and all the compounds were found low cytotoxic in the concentration range of 2.5–250 μM. Preliminary results indicate that these three compounds (1, 3 and 8) may be subjected to further investigations and it may be hoped that the present study will stimulate efforts towards the development of novel effective anti-amoebic agents.