Synthesis and Kinetic Testing of Tetrahydropyrimidine-2-thione and Pyrrole Derivatives as Inhibitors of the Metallo-β-lactamase from Klebsiella pneumonia and Pseudomonas aeruginosa

Metallo-β-lactamases (MBLs), produced by an increasing number of bacterial pathogens, facilitate the hydrolysis of many commonly used β-lactam antibiotics. There are no clinically useful antagonists against MBLs. Two sets of tetrahydropyrimidine-2-thione and pyrrole derivatives were synthesized and assayed for their inhibitory effects on the catalytic activity of the IMP-1 MBL from Pseudomonas aeruginosa and Klebsiella pneumoniae. Nine compounds tested (1a, 3b, 5c, 6b, 7a, 8a, 11c, 13a, and 16a) showed micromolar inhibition constants (K_i values range from ~20-80μm). Compounds 1c, 2b, and 15a showed only weak inhibition. In silico docking was employed to investigate the binding mode of each enantiomer of the strongest inhibitor, 5c (K_i=19±9μm), as well as 7a (K_i=21±10μm), the strongest inhibitor of the pyrrole series, in the active site of IMP-1.