Metronidazole containing pyrazole derivatives potently inhibit tyrosyl-tRNA synthetase: design, synthesis, and biological evaluation.

As an important enzyme in bacterial protein biosynthesis, tyrosyl-tRNA synthetase (TyrRS) has been an absorbing therapeutic target for exploring novel antibacterial agents. A series of metronidazole-based antibacterial agents has been synthesized and identified as TyrRS inhibitors with low cytotoxicity and significant antibacterial activity, especially against Gram-negative organisms. Of the compounds obtained, 4f is the most potent agent which inhibited the growth of Pseudomonas aeruginosa ATCC 13525 (MIC = 0.98 μg/mL) and exhibited TryRS inhibitory activity (IC50  = 0.92 μm). Docking simulation was performed to further understand its potency. Membrane-mediated apoptosis in P. aeruginosa was verified by flow cytometry.