Synthesis and Antimicrobial Evaluation of Some Simple Phenylhydrazones

A Okhifo, G. I. Ndukwe, I. R. Jack, O. J. Abayeh


The frequency of relapse and severity of some microbial infections call for continuous screening of natural and synthetic compounds for super inhibitory activity. In this research work, phenylhydrazine was reacted stoichiometrically with appropriate mole of acetone to give 1.19 g of compound A1 (acetone phenylhydrazone, a yellow oily product) with percentage yield of 87%. Compounds A2 (acetophenone phenylhydrazone), A3 (acetylacetone phenylhydrazone) and A4 (cyclohexanone phenylhydrazone) were similarly obtained by reacting the phenylhydrazine with acetophenone, acetylacetone and cyclohexanone respectively. The product yield for compounds A2, A3 and A4 were 1.112, 4.198 and 1.637 g with percentage yields of 89, 81 and 94% respectively Infrared (FT-IR) spectra of the compounds showed peaks at 1612, 1608, 1597 and 1603 cm-1 which were absorptions due C=N, for compounds A1, A2, A3 and A4 respectively. Purity of the compounds was ascertained using thin layer chromatography (TLC). The retention factors (Rf values) of the compounds were found to be 0.82, 0.82, 0.77 and 0.87 for compounds A1, A2, A3 and A4 respectively. The four synthesized phenylhydrazones were individually screened against five bacteria and two fungi strains using the Disc Diffusion Method. Minimum Inhibitory Concentrations (MICs) of the compounds against the growth of the microbes were determined and zones of inhibition for susceptible strains recorded. The synthesized compounds generally exhibited weak antibacterial activity compared to the standard drug (10 µg/ml Ciprofloxacin) used. However, compound A1 inhibited the growth of Escherichia coli, Staphylococcus aureus, and Salmonella typhi at MIC of 125 µg/ml.

Keywords: Phenylhydrazone, Synthesis, Phenylhydrazones, antibacterial, antifungal, drug-discovery

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