Relationship between the structure of newly synthesized derivatives of 1,3,4-oxadiazole containing 2-methylphenol and their antioxidant and antibacterial activities

Abstract

1,3,4-oxadiazole-5-thion ring(2) successfully formed at position six of 2-methylphenol and five of their thioalkyl(3a-e). Furthermore 6-(5-(Aryl)-1,3,4-oxadiazol-2-yl)-2-methylphenol (5a-i) were formed at position six by two method. The first method was from cyclization their correspondinghydrazones(4a-e) of 2-hydroxy-3-methylbenzohydrazide (1)using bromine in glacial acetic acid.The second method was from cyclization the hydrazide with aryl carboxylic acid in the presence of phosphorusoxy chloride. The newly synthesized compounds were characterized from their IR, NMR and mass spectra. The antioxidant properties of these compounds were screened by 2,2-Diphenyl-1-picrylhydrazide (DPPH) and ferric reducing antioxidant power (FRAP) assays. Compound (4d) and (5h) exhibited significant antioxidant properties in both assays, compared to ascorbic acid, while compound (4e) exhibited slightly less antioxidant properties than ascorbic acid. Antibacterial activity was tested for the twenty one compounds against eight microorganisms (gram negative and gram positive). Compound (4d)and (5d) exhibited significant antibacterial activities compared to Amoxicillin and Kanamycin as antibiotic standards.