Synthesis, Characterization and Evaluation of Antibacterial Activity of Six Novel 1,2,4-Triazole Derivatives against Standard and Medical Bacteria

Abstract 1,2,4-triazoles have been reported to possess a wide range of biological activities, including anticancer, antifungal, antiviral and antibacterial activities. Therefore, the current investigation is intended to synthesize six novel 1,2,4-triazole derivatives (designated as 2aa, 2ab, 2ac, 2bb, 2bd, and 2be). These derivatives were screened for their antibacterial activity against two Gram-negative bacteria isolated from clinical specimens (stool and ear exudates of infected patients) and two Gram-positive standard bacteria (Staphylococcus aureus ATCC29213 and Bacillus cereus ATCC11778) using both well diffusion and broth dilution methods. The chemical structures of the new 1,2,4-triazole derivatives were characterized by 1H and 13C-NMR spectra, in addition to elemental analysis. The bacterial strains designated as GN1 and GN2 were identified by biochemical and molecular methods and confirmed as new strains of Shigella sp., and Pseudomonas aeruginosa, respectively. All triazole derivatives were found to be active against bacteria with varying degrees. Some derivatives were found to have the same antibacterial activity as penicillin G (the positive control) against certain strains, for instance, 2ab, 2bd, and 2be against B. cereus ATCC11778. Interestingly, some compounds were more active than penicillin G against certain strains. The activity of 2aa against B. cereus ATCC11778 was higher than the activity of penicillin G, whereas 2ab and 2ac were more active than penicillin G against the clinical isolate P. aeruginosa. The variation seen in antimicrobial activity could be attributed to the difference in the substituent groups attached to the 1,2,4-triazole nucleus. In conclusion, these findings might hold promise for development of a new class of a novel expanded spectrum antibiotics against clinically important bacteria that are highly resistant to current antibacterial agents and associated with serious and life-threatening infections.