Synthesis and antiamoebic activity of 3,7-dimethyl-pyrazolo[3,4-e][1,2,4] triazin-4-yl thiosemicarbazide derivatives

A series of 3,7-dimethyl-pyrazolo[3,4-e][1,2,4]triazin-4-yl thiosemicarbazide derivatives 3-22 were prepared and evaluated in vitro against HM1:1MSS strain of Entamoeba histolytica, to identify the compounds for antiamoebic activity. They exhibited antiamoebic activity in the range (IC50 = 0.81-7.31 μM). The results were compared to the activity of known drug metronidazole. It is inferred from the in vitro studies that the compounds 10, 11, 17 and 18 were found to be significantly better inhibitors of E. histolytica since IC50 values in the μM range elicited by these compounds are much lower than metronidazole. Besides, compounds 11 and 17 have shown the most promising antiamoebic activity (IC50 = 0.81 μM of 11, IC50 = 0.84 μM of 17 versus IC50 = 1.81 μM of metronidazole). The study suggests the possibility of developing triazine analogues as potential drug candidates for antiamoebic activity.