Synthesis and biological evaluation of novel ß-lactam-metallo ß-lactamase inhibitors.

ß-lactamases are enzymes that deactivate ß-lactam antibiotics through a hydrolysis mechanism. There are two known types of ß-lactamases: serine ß-lactamases (SBLs) and metallo ß-lactamases (MBLs). The two existing strategies to overcome ß-lactamase-mediated resistance are (a) to develop novel ß-lactam antibiotics that are not susceptible to hydrolysis by these enzymes; or (b) to develop ß-lactamase inhibitors that deactivate the enzyme and thereby restore the efficacy of the co-administered antibiotics. Many commercially available SBL inhibitors are used in combination therapy with antibiotics to treat antimicrobial resistant infections; however, there are only a handful of MBL inhibitors undergoing clinical trials. In this study, we present 11 novel potential MBL inhibitors (via multi-step chemical synthesis), that have shown to completely restore the efficacy of meropenem (≤2 mg L-1) against New Delhi metallo-ß-lactamase (NDM) producing Klebsiella pneumoniae in vitro. These compounds contain a cyclic amino acid zinc chelator conjugated to various commercially available ß-lactam antibiotic scaffolds with the aim to improve the overall drug transport, lipophilicity, and pharmacokinetic/pharmacodynamic properties as compared to the chelator alone. Biological evaluation of compounds 24b and 24c has further highlighted the downstream application of these MBLs, since they are non-toxic at the selected doses. Time-kill assays indicate that compounds 24b and 24c exhibit sterilizing activity towards NDM producing Klebsiella pneumoniae in vitro using minimal concentrations of meropenem. Furthermore, 24b and 24c proved to be promising inhibitors of VIM-2 (Ki = 0.85 and 1.87, respectively). This study has revealed a novel series of ß-lactam MBLIs that are potent, efficacious, and safe leads with the potential to develop into therapeutic MBLIs.

Neutralizing Carbapenem Resistance by Co-Administering Meropenem with Novel ß-Lactam-Metallo-ß-Lactamase Inhibitors.

Virulent Enterobacterale strains expressing serine and metallo-ß-lactamases (MBL) genes have emerged responsible for conferring resistance to hard-to-treat infectious diseases. One strategy that exists is to develop ß-lactamase inhibitors to counter this resistance. Currently, serine ß-lactamase inhibitors (SBLIs) are in therapeutic use. However, an urgent global need for clinical metallo-ß-lactamase inhibitors (MBLIs) has become dire. To address this problem, this study evaluated BP2, a novel beta-lactam-derived ß-lactamase inhibitor, co-administered with meropenem. According to the antimicrobial susceptibility results, BP2 potentiates the synergistic activity of meropenem to a minimum inhibitory concentration (MIC) of ≤1 mg/L. In addition, BP2 is bactericidal over 24 h and safe to administer at the selected concentrations. Enzyme inhibition kinetics showed that BP2 had an apparent inhibitory constant (Kiapp) of 35.3 µM and 30.9 µM against New Delhi Metallo-ß-lactamase (NDM-1) and Verona Integron-encoded Metallo-ß-lactamase (VIM-2), respectively. BP2 did not interact with glyoxylase II enzyme up to 500 µM, indicating specific (MBL) binding. In a murine infection model, BP2 co-administered with meropenem was efficacious, observed by the >3 log10 reduction in K. pneumoniae NDM cfu/thigh. Given the promising pre-clinical results, BP2 is a suitable candidate for further research and development as an (MBLI).

In Vitro and In Vivo Development of a ß-Lactam-Metallo-ß-Lactamase Inhibitor: Targeting Carbapenem-Resistant Enterobacterales.

ß-lactams are the most prescribed class of antibiotics due to their potent, broad-spectrum antimicrobial activities. However, alarming rates of antimicrobial resistance now threaten the clinical relevance of these drugs, especially for the carbapenem-resistant Enterobacterales expressing metallo-ß-lactamases (MBLs). Antimicrobial agents that specifically target these enzymes to restore the efficacy of last resort ß-lactam drugs, that is, carbapenems, are therefore desperately needed. Herein, we present a cyclic zinc chelator covalently attached to a ß-lactam scaffold (cephalosporin), that is, BP1. Observations from in vitro assays (with seven MBL expressing bacteria from different geographies) have indicated that BP1 restored the efficacy of meropenem to ≤ 0.5 mg/L, with sterilizing activity occurring from 8 h postinoculation. Furthermore, BP1 was nontoxic against human hepatocarcinoma cells (IC50 > 1000 mg/L) and exhibited a potency of (Kiapp) 24.8 and 97.4 µM against Verona integron-encoded MBL (VIM-2) and New Delhi metallo ß-lactamase (NDM-1), respectively. There was no inhibition observed from BP1 with the human zinc-containing enzyme glyoxylase II up to 500 µM. Preliminary molecular docking of BP1 with NDM-1 and VIM-2 sheds light on BP1's mode of action. In Klebsiella pneumoniae NDM infected mice, BP1 coadministered with meropenem was efficacious in reducing the bacterial load by >3 log10 units' postinfection. The findings herein propose a favorable therapeutic combination strategy that restores the activity of the carbapenem antibiotic class and complements the few MBL inhibitors under development, with the ultimate goal of curbing antimicrobial resistance.

A 2018-2019 patent review of metallo beta-lactamase inhibitors.

INTRODUCTION: Antibiotic resistance caused by beta-lactamase expressing bacteria poses a concern given its global dissemination and proliferation. The emergence of the metallo beta-lactamases is an indefinite health threat toward which current antibiotics have limited clinical efficacy. One solution is to develop metallo beta-lactamase inhibitors (MBLIs) capable of restoring the activity of beta-lactam drugs. AREAS COVERED: This review focuses on potential metallo beta-lactamase inhibitors that have been patented during the period of 2018-2019. The aim is to provide insight into the diverse class of compounds which exhibit a synergistic inhibitory effect on carbapenem-resistant bacteria, when co-administered with a beta-lactam antibiotic. EXPERT OPINION: The treatment strategy, of creating a broad-spectrum beta-lactamase inhibitor, is beneficial to the health sector as well as rural communities. Unfortunately, most of the inhibitors lack published data from both in vitro and in vivo evaluation, thus preventing an expert opinion on the likelihood to progress as candidates for clinical trials. From this report, the bismuth complexes, pyridinyl-nicotinamide derived sugars, boronic acid, and thiazole sulfonamide derivatives, portray promising properties for further advancement. Since there is currently no FDA approved MBLI, there remains an urgent need for the development of these combination treatment strategies.