Exploring the Antibacterial Properties of Hydrazone Schiff Bases Derived from 4-Aminodimethylbenzaldehyde: Synthesis, Characterization, and Activity Assessment

Grema A. Mala, Ibrahim M. Wakil, Hussaini Garba, Abubakar Mindia, Salihu A. Musa, Abubakar A. Ahmed, Mohammed B. Fugu, and Ibrahim Waziri*

1Department of Pure and Applied Chemistry, University of Maiduguri, P.M.B. 1069, Maiduguri, Borno
State, Nigeria

*Corresponding author’s Email: triumph2236@gmail.com, doi.org/10.55639/607.313029


The urgent need for new antibiotics has fueled the synthesis and evaluation of  organic molecules for their antibacterial activity. This study focuses on the synthesis of two hydrazone Schiff base compounds, (E)-N-(4-(dimethylamino)benzylidene)benzohydrazide (HSB1) and (E)-N-(4-(dimethylamino)benzylidene)-4-methylbenzohydrazide (HSB2). The compounds were synthesized through a condensation reaction between benzohydrazide, p￾toluic hydrazide, and 4-aminodimethylbenzaldehyde in methanol solvent at room temperature, utilizing formic acid as a catalyst. The structures of the compounds were elucidated through comprehensive physicochemical and spectroscopic analyses, including elemental CHN-analysis, 1H and 13C NMR, FTIR, UV-Vis, and mass spectroscopies. These characterization techniques confirmed the successful formation of the compounds. The synthesized compounds were evaluated for their antibacterial activity, comparing them to the standard antibiotic ciprofloxacin. The in vitro disc diffusion method was employed to test the compounds against selected pathogenic bacteria, including Gram-positive strains, Staphylococcus aureus and Streptococcus pyogenes, as well as Gram-negative strains Escherichia coli and Klebsiella pneumoniae. The results demonstrated that the compounds exhibited concentration-dependent activity, with a preference for Gram-positive pathogens. Notably, HSB2 displayed superior antibacterial activity compared to HSB1. The study also postulated the structural activity relationship (SAR) and mode of action of the compounds. The SAR analysis suggested that the presence of specific chemical groups, such as aromatic rings and the hydrazone Schiff base  moiety, contribute to their antibacterial activity.


Bacterial resistance,
Schiff base,
Structural activity