Design, Synthesis, and Biological Evaluation of New 1H-Imidazole-2-Carboxylic Acid Derivatives as Metallo-β-Lactamase Inhibitors

Approachable Synthetic Methodologies for Second-Generation β-Lactamase Inhibitors: A Review

Some antibiotics that are frequently employed are β-lactams. In light of the hydrolytic process of β-lactamase, found in Gram-negative bacteria, inhibitors of β-lactamase (BLIs) have been produced. Examples of first-generation β-lactamase inhibitors include sulbactam, clavulanic acid, and tazobactam. Many kinds of bacteria immune to inhibitors have appeared, and none cover all the β-lactamase classes. Various methods have been utilized to develop second-generation β-lactamase inhibitors possessing new structures and facilitate the formation of diazabicyclooctane (DBO), cyclic boronate, metallo-, and dual-nature β-lactamase inhibitors. This review describes numerous promising second-generation β-lactamase inhibitors, including vaborbactam, avibactam, and cyclic boronate serine-β-lactamase inhibitors. Furthermore, it covers developments and methods for synthesizing MβL (metallo-β-lactamase inhibitors), which are clinically effective, as well as the various dual-nature-based inhibitors of β-lactamases that have been developed. Several combinations are still only used in preclinical or clinical research, although only a few are currently used in clinics. This review comprises materials on the research progress of BLIs over the last five years. It highlights the ongoing need to produce new and unique BLIs to counter the appearance of multidrug-resistant bacteria. At present, second-generation BLIs represent an efficient and successful strategy.

Drug Discovery in the Field of β-Lactams: An Academic Perspective

β-Lactams are the most widely prescribed class of antibiotics that inhibit penicillin-binding proteins (PBPs), particularly transpeptidases that function in peptidoglycan synthesis. A major mechanism of antibiotic resistance is the production of β-lactamase enzymes, which are capable of hydrolyzing β-lactam antibiotics. There have been many efforts to counter increasing bacterial resistance against β-lactams. These studies have mainly focused on three areas: discovering novel inhibitors against β-lactamases, developing new β-lactams less susceptible to existing resistance mechanisms, and identifying non-β-lactam inhibitors against cell wall transpeptidases. Drug discovery in the β-lactam field has afforded a range of research opportunities for academia. In this review, we summarize the recent new findings on both β-lactamases and cell wall transpeptidases because these two groups of enzymes are evolutionarily and functionally connected. Many efforts to develop new β-lactams have aimed to inhibit both transpeptidases and β-lactamases, while several promising novel β-lactamase inhibitors have shown the potential to be further developed into transpeptidase inhibitors. In addition, the drug discovery progress against each group of enzymes is presented in three aspects: understanding the targets, screening methodology, and new inhibitor chemotypes. This is to offer insights into not only the advancement in this field but also the challenges, opportunities, and resources for future research. In particular, cyclic boronate compounds are now capable of inhibiting all classes of β-lactamases, while the diazabicyclooctane (DBO) series of small molecules has led to not only new β-lactamase inhibitors but potentially a new class of antibiotics by directly targeting PBPs. With the cautiously optimistic successes of a number of new β-lactamase inhibitor chemotypes and many questions remaining to be answered about the structure and function of cell wall transpeptidases, non-β-lactam transpeptidase inhibitors may usher in the next exciting phase of drug discovery in this field.

An updated patent review of metallo-β-lactamase inhibitors (2020-2023)

INTRODUCTION

Metallo-β-lactamases (MBLs) are enzymes produced by bacteria that confer resistance to most β-lactam antibiotics, including carbapenems, which have the broadest spectrum of activity. This resistance mechanism poses a significant threat to public health as it drastically reduces treatment options for severe bacterial infections. Developing effective inhibitors against MBLs is crucial to restore susceptibility to β-lactam antibiotics.

AREAS COVERED

This review aims to provide an updated analysis of patents describing novel MBL inhibitors and their potential therapeutic applications that were filed between January 2020 and May 2023.

EXPERT OPINION

Significant advancements were made in the development of selective MBL inhibitors with zinc-binding and zinc-chelating mechanisms of action. Dual inhibitors, targeting simultaneously both serine-β-lactamases (SBLs) and MBLs, represent an interesting alternative approach that is increasingly pertinent for the treatment of infections involving multiple β-lactamases from different Ambler classes. Most examples of MBL-specific inhibitors were focused on the treatment of MBL-mediated infections in Enterobacterales, where IMP-1 was a more difficult target compared with VIM-1 or NDM-1, and much less on Pseudomonas aeruginosa or Acinetobacter baumannii, which are more challenging to address.

Small-molecule inhibitors of bacterial-producing metallo-β-lactamases: insights into their resistance mechanisms and biochemical analyses of their activities

Antibiotic resistance (AR) remains one of the major threats to the global healthcare system, which is associated with alarming morbidity and mortality rates. The defence mechanisms of Enterobacteriaceae to antibiotics occur through several pathways including the production of metallo-β-lactamases (MBLs). The carbapenemases, notably, New Delhi MBL (NDM), imipenemase (IMP), and Verona integron-encoded MBL (VIM), represent the critical MBLs implicated in AR pathogenesis and are responsible for the worst AR-related clinical conditions, but there are no approved inhibitors to date, which needs to be urgently addressed. Presently, the available antibiotics including the most active β-lactam-types are subjected to deactivation and degradation by the notorious superbug-produced enzymes. Progressively, scientists have devoted their efforts to curbing this global menace, and consequently a systematic overview on this topic can aid the timely development of effective therapeutics. In this review, diagnostic strategies for MBL strains and biochemical analyses of potent small-molecule inhibitors from experimental reports (2020-date) are overviewed. Notably, N1 and N2 from natural sources, S3-S7, S9 and S10 and S13-S16 from synthetic routes displayed the most potent broad-spectrum inhibition with ideal safety profiles. Their mechanisms of action include metal sequestration from and multi-dimensional binding to the MBL active pockets. Presently, some β-lactamase (BL)/MBL inhibitors have reached the clinical trial stage. This synopsis represents a model for future translational studies towards the discovery of effective therapeutics to overcome the challenges of AR.