DESIGN AND BIO-EVALUATION OF SOME IMINES BASED ON THE CHALCONE SCAFFOLD AGAINST GRAM-POSITIVE AND GRAM-NEGATIVE BACTERIA

Abstract

The increasing multi-drug resistance of bacterial pathogens to conventional antibiotics necessitates the development of novel antimicrobial agents. In this study, three imines, (E)-1-(2,4-dinitrophenyl)-2-((E)-1-(4-methoxyphenyl)-3-(3,4,5-trimethoxyphenyl)allylidene)hydrazine (SAAB1), (E)-1-(2,4-dinitrophenyl)-2-((E)-1-(4-methoxyphenyl)-3-(4-nitrophenyl)allylidene)hydrazine (SAAB2) (E)-1-((E)-1-(4-chlorophenyl)-3-(4-methoxyphenyl)allylidene)-2-(2,4-dinitrophenyl)hydrazine were synthesized through a two-step condensation reaction between substituted chalcones and 2,4-dinitrophenylhydrazine (DNPH). The chalcones were synthesized via Claisen-Schmidt condensation of substituted benzaldehyde and acetophenone using 20% aqueous NaOH and monitored by TLC. The structures of the synthesized imines were elucidated using Fourier transform infrared spectroscopy (FTIR), with characteristic 1598 – 1605 cm-1 imine (>C=N) and 1320 – 1350 cm-1 nitro (-NO2) group absorptions confirming successful hydrazone formation. The compounds were screened for antibacterial activity against two clinically resistant bacterial strains: Staphylococcus aureus (Gram-positive) and Pseudomonas aeruginosa (Gram-negative), using the agar well diffusion method. DMSO was used as the negative control while ciprofloxacin (10 µg/mL) served as the positive control. Preliminary results revealed moderate to significant activity, particularly against S. aureus, suggesting structure-dependent bioactivity. These findings underscore the potential of chalcone-derived hydrazone imines as lead scaffolds for developing new antibacterial agents.