SYNTHESIS, SPECTRAL CHARACTERIZATION AND ANTIMICROBIAL EVALUATION OF NOVEL THIOPHENE HYDRAZONE DERIVATIVES A1 AND A3 AGAINST AMPICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS

The emergence of antimicrobial resistance has created an urgent demand for the development of novel antibacterial agents possessing improved efficacy against resistant bacterial pathogens. In the present investigation, two novel thiophene-based hydrazone derivatives, namely (Z)-1-(3,4-dimethylphenyl)-2-((5-methylthiophen-2-)methylene)hydrazine (A1) and (Z)-1-(4-methoxyphenyl)-2-((5-methylthiophen-2-yl)methylene)hydrazine (A3), were synthesized through Schiff base condensation of 5-methylthiophene-2-carbaldehyde with substituted phenylhydrazines in ethanolic medium using glacial acetic acid as catalyst. The synthesized compounds were isolated as yellow crystalline solids and characterized using ¹H NMR, ¹³C NMR, mass spectrometry, and elemental analysis. Spectral studies confirmed successful hydrazone formation through characteristic azomethine resonances and molecular ion peaks. Antimicrobial screening against ampicillin-resistant Staphylococcus aureus demonstrated that compound A1 exhibited comparatively higher antibacterial activity than A3. The improved activity of A1 may be attributed to enhanced hydrophobicity caused by dimethyl substitution, whereas methoxy substitution in A3 resulted in relatively lower antibacterial potency. The study highlights the significance of aromatic substitution in modulating antimicrobial activity within thiophene hydrazone scaffolds.