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Super bacterial infection caused by metallo‐β‐lactamases (MβLs) has posed a serious public health threat, while developing inhibitors of MβLs is an ideal strategy to combat drug‐resistance. Here, seventeen sulfonylureas were synthesized and confirmed. Biological assay shown that these molecules effectively inhibited MβL ImiS, with an IC50 value in the range of 29.5–188.2 μM, and the best inhibitor competitively and irreversibly inhibited ImiS with a Ki value of 15.2 μM. Structure‐activity relationship analysis revealed that the chlorine‐substituted phenyl significantly raised inhibitory activity of sulfonylureas on ImiS. Antibacterial and chessboard dilution assays shown that the most sulfonylureas tested enhanced antimicrobial effect of meropenem (MER) on E. coli‐ImiS, and the two inhibitors with best effect resulted in an 8‐fold reduction in MIC of MER. Mice tests shown that the best inhibitor synergizing MER virtually diminished the load of E. coli‐ImiS in spleen and liver. Docking study revealed that the sulfonylurea reacts with ImiS mainly through the sulfonyl group, in which one of oxygen atoms coordinates to Zn(II), and forms two hydrogen bonds with Lys224 (2.1 Å) and His263 (3.1 Å). This work revealed the sulfonylureas are promising candidates for the development of ImiS inhibitors. [ABSTRACT FROM AUTHOR]

Abstract: One of the most common way that bacteria become resistant to antibiotics is by the production of metallo-β-lactamases (MβLs) to hydrolyze the β-lactam-containing antibiotics. In this paper, the thermodynamic parameters of benzylpenicillin hydrolysis with B1 subclasses MβL CcrA (carbapenem and cephamycin resistance) from Bacteroides fragilis were determined by microcalorimetry. The activation free energy is 87.90±0.03, 88.99±0.01, 89.93±0.04 and 90.93±0.05kJmol−1 at 293.15, 298.15, 303.15 and 308.15K, activation enthalpy is 29.21±0.03kJmol−1, activation entropy is −200.34±0.08Jmol−1 K−1, the reaction order is 1.4, and the apparent activation energy E is 31.71kJmol−1. The thermodynamic characterization indicated that CcrA prefer to hydrolyze penicillins among three kinds of β-lactam-containing antibiotics. [Copyright &y& Elsevier]

In an effort to understand the reactions of antibiotics hydrolysis with metallo-β-lactamases (MβLs), the thermokinetic parameters of cefazolin hydrolysis with B1 subclass MβL CcrA from Bacteroides fragilis were determined by microcalorimetric method. The values of activation free energy $$ \Updelta G_{ \ne }^{\theta } $$ are 88.032 ± 0.038, 89.075 ± 0.025, 90.095 ± 0.034, and 91.261 ± 0.044 kJ mol at 293.15, 298.15, 303.15, and 308.15 K, respectively, the activation enthalpy $$ \Updelta H_{ \ne }^{\theta } $$ is 25.278 ± 0.005 kJ mol, the activation entropy $$ \Updelta S_{ \ne }^{\theta } $$ is −213.99 ± 0.14 J mol K, the apparent activation energy E is 27.776 kJ mol, and the reaction order is 1.4. The results indicated that the cefazolin hydrolysis with CcrA is an exothermic and spontaneous reaction. An association between the thermokinetic and kinetic parameters was revealed, which is that the catalytic constant K increase with increase in $$ \Updelta H_{ \ne }^{\theta } $$. [ABSTRACT FROM AUTHOR]

In an effort to understand the reaction of antibiotic hydrolysis with B2 metallo-β-lactamases (MβLs), the thermodynamic parameters of imipenem hydrolysis catalyzed by metallo-β-lactamase ImiS from Aeromonas veronii bv. sobria were determined by microcalorimetric method. The values of activation free energy $$ \Updelta G_{ \ne }^{\theta } $$ are 86.400 ± 0.043, 87.543 ± 0.034, 88.772 ± 0.024, and 89.845 ± 0.035 kJ mol at 293.15, 298.15, 303.15, and 308.15 K, respectively, activation enthalpy $$ \Updelta H_{ \ne }^{\theta } $$ is 18.586 ± 0.009 kJ mol, activation entropy $$ \Updelta S_{ \ne }^{\theta } $$ is −231.34 ± 0.12 J mol K, apparent activation energy E is 21.084 kJ mol, and the reaction order is 1.5. The thermodynamic parameters reveal that the imipenem hydrolysis catalyzed by metallo-β-lactammase ImiS is an exothermic and spontaneous reaction. [ABSTRACT FROM AUTHOR]

Abstract: In an effort to study on the antibiotic resistance in bacteria, we first report the thermokinetic parameters of the imipenem hydrolysis with B1 subclasses metallo-β-lactamase CcrA from Bacteroides fragilis. The values of activation free energy is 87.54±0.03, 88.78±0.03, 89.90±0.04 and 91.06±0.02kJmol−1 at 293.15, 298.15, 303.15 and 308.15K, respectively, the activation enthalpy is 19.10±0.01kJmol−1, the activation entropy is −233.56±0.09Jmol−1 K−1 and the apparent activation energy E is 21.598kJmol−1. The results reveal that the imipenem hydrolysis catalyzed by CcrA is an exothermic and spontaneous reaction with reaction order of 1.4, and has a lower and than the cefazolin hydrolysis with same enzyme. [Copyright &y& Elsevier]

[Display omitted] • The novel thiosemicarbazones specifically inhibit NDM-1 and ImiS, with an IC 50 in the range of 0.37–21.35 and 0.45–8.76 μM. • The thiosemicarbazones alone sterilize resistant bacteria E. coli -ImiS and E. coli -NDM-1, with a MIC value in the scope of 8–128 μg/mL. • Partial thiosemicarbazones enhanced the antimicrobial activity of Meropenem on E. coli -ImiS and E. coli -NDM-1. • A thiosemicarbazone in combination with Meropenem significantly reduced the bacterial load in liver and spleen of mice. The superbug infection mediated by metallo-β-lactamases (MβLs) has grown into anemergent health threat, and development of MβL inhibitors is an ideal strategy to combat the infection. In this work, twenty-five thiosemicarbazones 1a - e , 2a - e , 3a - e , 4a - d, 5a-d and 6a-b were synthesized and assayed against MβLs ImiS, NDM-1 and L1. The gained molecules specifically inhibited NDM-1 and ImiS, exhibiting an IC 50 value in the range of 0.37–21.35 and 0.45–8.76 µM, and 2a was found to be the best inhibitor, with an IC 50 of 0.37 and 0.45 µM, respectively, using meropenem (MER) as substrate. Enzyme kinetics and dialysis tests revealed and confirmed by ITC that 2a is a time-and dose-dependent inhibitor of ImiS and NDM-1, it competitively and reversibly inhibited ImiS with a K i value of 0.29 µM, but irreversibly inhibited NDM-1. Structure-activity relationship disclosed that the substitute dihydroxylbenzene significantly enhanced inhibitory activity of thiosemicarbazones on ImiS and NDM-1. Most importantly, 1a - e , 2a - e and 3a - b alone more strongly sterilized E. coli -ImiS and E. coli -NDM-1 than the MER, displaying a MIC value in the range of 8–128 μg/mL, and 2a was found to be the best reagent with a MIC of 8 and 32 μg/mL. Also, 2a alone strongly sterilized the clinical isolates EC01, EC06-EC08, EC24 and K. pneumonia -KPC-NDM, showing a MIC value in the range of 16–128 μg/mL, and exhibited synergistic inhibition with MER on these bacteria tested, resulting in 8–32-fold reduction in MIC of MER. SEM images shown that the bacteria E. coli -ImiS, E. coli -NDM-1, EC24, K. pneumonia -KPC and K. pneumonia -KPC-NDM treated with 2a (64 μg/mL) suffered from distortion, emerging adhesion between individual cells and crumpled membranes. Mice tests shown that monotherapy of 2a evidently limited growth of EC24 cells, and in combination with MER, it significantly reduced the bacterial load in liver and spleen. Docking studies suggest that the 2,4-dihydroxylbenzene of 2a acts as zinc-binding group with the Zn(II) and the residual amino acids in CphA active center, tightly anchoring the inhibitor at active site. This work offered a promising scaffold for the development of MβLs inhibitors, specifically the antimicrobial for clinically drug-resistant isolates. [ABSTRACT FROM AUTHOR]

Abstract: In an effort to identify novel, broad-spectrum inhibitors against the metallo-β-lactamases (MβLs), several N-heterocyclic derivatives were tested as inhibitors of MβLs CcrA, ImiS, and L1, which are representative enzymes from the distinct MβL subclasses. Three N-heterocyclic dicarboxylic acid derivatives were competitive inhibitors of CcrA and L1, exhibiting K i values ⩽2μM, while only 2,4-thiazolidinedicarboxylic acid (1b) was a competitive inhibitor of ImiS. Two 2-mercapto-1,3,4-thiadiazole derivatives were noncompetitive inhibitors of CcrA and ImiS, exhibiting K i values <7μM; however, these same compounds did not inhibit L1. Two 2-mercapto-1,3,4-triazole derivatives were shown not to inhibit any of the tested MβLs. The N-heterocyclic derivatives were tested for antibacterial activity by examining the MIC values for existing antibiotics in the presence/absence of these derivatives. Consistent with the steady-state inhibition data, the inclusion of three N-heterocyclic dicarboxylic acid derivatives resulted in lower MIC values when using Escherichia coli BL21(DE3) cells containing the CcrA or L1 plasmids or Klebsiella pneumoniae (ATCC 700603), while 1b was the only dicarboxylic acid derivative to lower the MIC value of E. coli cells containing the ImiS plasmid. Inclusion of the 2-mercapto-1,3,4-thiadiazole derivatives resulted in lower MIC values for E. coli cells containing ImiS or L1 plasmids; however, these derivatives did not alter the MIC values for K. pneumoniae or E. coli cells containing the L1 plasmid. None of the N-heterocyclic derivatives affected the MIC of two methicillin resistant Staphylococcus aureus (MRSA) strains. Taken together, these studies demonstrate that N-heterocyclic dicarboxylic acids 1a–c and pyridylmercaptothiadiazoles 2a,b are good scaffolds for future broad-spectrum inhibitors of the MβLs. [Copyright &y& Elsevier]