Synthesis and evaluation of antioxidant and antibacterial activities of new substituted bis(1,3,4-oxadiazoles), 3,5-bis(substituted) pyrazoles and isoxazoles

Two series of five membered heterocyclic bis(1,3,4-oxadiazole) derivatives 2(a–h) and 3,5-bis(substituted)pyrazoles, isoxazoles 3(a,b,d–i), 4(a–c) were synthesized via oxidative cyclization of some diaroylhydrazones using chloramine-T and cyclocondensation reaction with hydrazine hydrate and hydroxylamine hydrochloride, respectively. The newly synthesized compounds were screened for antioxidant and anti-microbial activities. Compounds 2(b), 3(b), and 4(a) showed higher antioxidant activity at 10 μg/ml while compounds 2(a), 3(a), 3(f), and 4(a) exhibited better anti-microbial activity at 100 μg/ml compared with standard vitamin C and ciprofloxacin, respectively. Structures of newly synthesized compounds were confirmed by elemental analysis and spectral IR, 1H NMR, and 13C NMR data.

Graphical abstractNovel bis(1,3,4-oxadiazole) derivatives 2(a–h) and 3,5-bis(substituted)pyrazoles 3(a,b,d–i) and isoxazoles 4(a–c) were synthesized and evaluated for their antioxidant and antibacterial activities and results were compared with standard.Figure optionsDownload full-size imageDownload as PowerPoint slide