Design, synthesis and antibacterial activities of 5-(pyrazin-2-yl)-4H-1,2,4-triazole-3-thiol derivatives containing Schiff base formation as FabH inhibitory

A series of novel schiff base derivatives (H1-H20) containing pyrazine and triazole moiety have been designed and synthesized, and their biological activities were also evaluated as potential inhibitors of β-ketoacyl-acyl carrier protein synthase III (FabH). These compounds were assayed for antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis and Bacillus amyloliquefaciens and selected compounds among them were tested for their Escherichia coli FabH inhibitory activity. Based on the biological data, compound H17 showed the most potent antibacterial activity with MIC values of 0.39-1.56 μg/mL against the tested bacterial strains and exhibited the most potent E. coli FabH inhibitory activity with IC50 of 5.2 μM, being better than the positive control Kanamycin B with IC50 of 6.3 μM. Furthermore, docking simulation was performed to position compound H17 into the E. coli FabH active site to determine the probable binding conformation. This study indicated that compound H17 has demonstrated significant E. coli FabH inhibitory activity as a potential antibacterial agent and provides valuable information for the design of E. coli FabH inhibitors.