Synthesis, characterization, and antibacterial evaluation of new vanillic acid derivatives

Abstract

Hydrazide Schiff bases (hydrazones) and 2,5-disubstituted-1,3,4-oxadiazole derivatives exhibit diverse biological activities that include antibacterial, antifungal, antitubercular, antiviral, anticancer, anti-inflammatory, and analgesia; so that new derivatives, compounds (5-8) of vanillic acid based on 1,3,4-oxadiazole as scaffold unit were synthesized through multi-steps, and characterized by thin layer chromatography and spectroscopically by Fourier-transform Infrared (FTIR) and Proton nuclear magnetic resonance (1HNMR). Compounds (5-8) were evaluated for their antibacterial activity by the disk diffusion method. Compounds (5-8) were showed moderate and comparable to the activities of amoxicillin and isoniazid against Escherichia coli (E. coli), but less than that of cefixime and nitrofurantoin which their activities were high. Compound (6) and (7) had shown moderate and comparable to the activities of amoxicillin and cefixime against Klebsiella pneumoniae (K. pneumoniae), but less than that of nitrofurantoin which its activity was high. Compound (6) and (7) had shown moderate and comparable to the activity of amoxicillin against Staphylococcus aureus (S. aureus), while the activities of cefixime and nitrofurantoin were high. Compound (6) was moderately active against Bacillus subtilis (B. subtilis), while the activities of amoxicillin, cefixime, and nitrofurantoin were high.