Novel Hydrazide Hydrazone Derivatives as Antimicrobial Agents: Design, Synthesis, and Molecular Dynamics

Abstract

Ester 2 was produced by reacting thiourea derivative 1 with ethyl 2-chloro-3-oxobutanoate in MeOH containing piperidine. Hydrazide 3 was produced by reacting the latter ester with hydrazine hydrate in EtOH at reflux. By reacting hydrazide 3 with aromatic/heterocyclic aldehydes, twelve derivatives of hydrazide hydrazone 5a–l were produced. Spectral measurements and elemental analysis verified the molecular structure. Compounds 2, 5a, 5c, 5d, and 5f had strong effects on all the pathogenic bacterial strains according to an evaluation of the antimicrobial qualities of the synthetic compounds. With inhibitory zone diameters ranging from 16 to 20.4 mm, hydrazide hydrazone 5f exhibited the strongest activity. Additionally, the minimum inhibitory concentration (MIC) was assessed. The best outcomes were found with hydrazones 5c and 5f. For B. subtilis, the MIC of 5c was 2.5 mg/mL. For E. coli and K. pneumoniae, the MIC of 5f was 2.5 mg/mL. The molecular mechanics-generalized born surface area (MM/GBSA) was utilized to compute binding free energies via a molecular dynamics simulation analysis of the most active compounds, 5f and 5c. Moreover, computational analyses demonstrated that 5f had a substantial affinity for the active site of DNA gyrase B, suggesting that this compound could be a strong platform for new structure-based design efforts.