Studies of Biologically Active Heterocycles: Synthesis, Characterization and Antimicrobial Activity of Some 2,5-Disubstituted-1,3,4-Oxadiazoles

Abstract

1,3,4-oxadiazoles are important because of its versatile biological actions. In the present study, several 2,5-disubstituted-1,3,4-oxadiazoles (3a-o) have been synthesized by the condensation of 4-hydroxybenzohydrazide (1) with various aromatic acids (2a-o) in presence of phosphorus oxychloride. The structures of the newly synthesized compounds have been established on the basis of elemental analysis, UV, IR and 1H NMR spectral data. The synthesized compounds were screened for their in vitro growth inhibiting activity against different strains of bacteria and fungi viz., Staphylococcus aureus, Bacillus subtilis, Bacillus megaterium, Escherichia coli, Pseudomonas aeruginosa, Shigella dysenteriae, Candida albicans, Aspergillus niger and Aspergillus flavus and the results were compared with the standard antibiotics such as chloramphenicol (50?g/ml) and Griseofulvin (50?g/ml) using agar diffusion technique. Compounds 3b, 3e, 3g, 3h, 3j, 3m and 3n exhibited strong antibacterial activity and compounds 3a, 3d, 3g, 3h and 3i showed good antifungal activity. Key words: 2,5-disubstituted-1,3,4-oxadiazoles, 4-hydroxybenzohydrazide, phosphorus oxychloride, antimicrobial evaluation, agar well diffusion method. Dhaka Univ. J. Pharm. Sci. 6(2): 69-75, 2007 (December)