In this article, a new series of 1,3,4-oxadiazoles, 1,2,4-triazoles, and 1,3,4-thiadiazoles were synthesized from the intermediates of hydrazone and thiosemicarbazide derivatives. All the compounds were evaluated for in vitro antibacterial activity using method of paper disc diffusion and nutrition broth dilution. The antibacterial data revealed that 3-aryl-4-(1,3-diphenyl-4-pyrazole-formyl)-1,2,4-triazoline-5-thione showed good activity against tested Gram-positive bacteria.

Key words: pyrazole, thiadiazole, oxadiazole, triazolam, antibacterial activity