Discovery of Novel Chemical Series of OXA-48 β-Lactamase Inhibitors by High-Throughput Screening

The major cause of bacterial resistance to β-lactams is the production of hydrolytic β-lactamase enzymes. Nowadays, the combination of β-lactam antibiotics with β-lactamase inhibitors (BLIs) is the main strategy for overcoming such issues. Nevertheless, particularly challenging β-lactamases, such as OXA-48, pose the need for novel and effective treatments. Herein, we describe the screening of a proprietary compound collection against Klebsiella pneumoniae OXA-48, leading to the identification of several chemotypes, like the 4-ideneamino-4H-1,2,4-triazole (SC_2) and pyrazolo[3,4-b]pyridine (SC_7) cores as potential inhibitors. Importantly, the most potent representative of the latter series (ID2, AC50 = 0.99 μM) inhibited OXA-48 via a reversible and competitive mechanism of action, as demonstrated by biochemical and X-ray studies; furthermore, it slightly improved imipenem’s activity in Escherichia coli ATCC BAA-2523 β-lactam resistant strain. Also, ID2 showed good solubility and no sign of toxicity up to the highest tested concentration, resulting in a promising starting point for further optimization programs toward novel and effective non-β-lactam BLIs.

Maintaining a High-Quality Screening Collection: The GSK Experience

The storage of screening collections in DMSO is commonplace in the pharmaceutical industry. To ensure a high-quality screening collection, and hence effective and efficient high-throughput screening, all compounds entering the GlaxoSmithKline (GSK) screening collection undergo a liquid chromatography–mass spectrometry (LC-MS) quality control (QC). It is generally accepted that even under optimal conditions, a small percentage of these compounds are unstable after prolonged storage in DMSO. This article presents how these QC data can be mined using a data-driven clustering algorithm to identify chemical substructures likely to cause degradation in DMSO. This knowledge provides new structural filters for use in excluding compounds with these undesirable substructures from the collection. This information also suggests an efficient, targeted approach to compound collection clean-up initiatives. Stability studies are also designed to maintain a high-quality screening collection. To define the best practice for the storage and handling of solution samples, GSK has undertaken stability experiments for two decades, initially to support the implementation of new automated liquid stores and, subsequently, to enhance storage and use of compounds in solution through an understanding of compound degradation under storage and assay conditions.

Steady-state enzyme kinetics

Steady-state enzyme kinetics is a cornerstone technique of biochemistry and related sciences since it allows the characterization and quantification of enzyme behaviour. Enzyme kinetics is widely used to investigate the physiological role of enzymes, determine the effects of mutations and characterize enzyme inhibitors. Well-known examples of enzyme inhibitors used to treat diseases include anti-infectives (e.g., penicillin, clavulanic acid and HIV protease inhibitors); anti-inflammatories (e.g., aspirin and ibuprofen); cholesterol-lowering statins; tyrosine kinase inhibitors used to treat cancer; and Viagra. Commonly, new disease treatments are discovered by using enzyme kinetics to identify the few active compounds residing within a large compound collection (‘high-throughput screening’). The subject of enzyme kinetics is typically introduced to first-year undergraduates with a mathematical description of behaviour. This Beginners Guide will give a brief overview of experimental enzyme kinetics and the characterization of enzyme inhibitors. Colorimetric assays using a microtitre plate will be considered, although most principles also apply to other assays.

Chemical phylogenetics of the staphylococcal quorum sensing landscape

Staphylococci utilize secreted autoinducing peptides (AIPs) to regulate group behaviour through a process called quorum sensing (QS). Here, we survey the QS interaction landscape within the Staphylococcus genus by assembling a unique compound collection, comprising all the currently known AIPs. These ribosomally synthesized and posttranslationally modified peptides (RiPPs) were obtained by chemical synthesis and mapping of their ability to modulate QS was evaluated using reporter strains of common human and animal colonizing pathogens (S. aureus, S. epidermidis, S. lugdunensis). The resulting map of >200 native QS interactions provides a holistic view of nodes that contribute to the complex signalling network within the Staphylococcus genus. This overview reveals surprising cross-species QS induction and identify the first pan-inhibitory AIP, which is then shown to attenuate MRSA induced skin infection in a mouse model. Our results expose a complex universe of possible staphylococcal interactions and provide further impetus for development of therapeutics based on QS modulators targeting antibiotic resistant pathogens.

Drug Repurposing Screen for Compounds Inhibiting the Cytopathic Effect of SARS-CoV-2

Drug repurposing is a rapid approach to identify therapeutics for the treatment of emerging infectious diseases such as COVID-19. To address the urgent need for treatment options, we carried out a quantitative high-throughput screen using a SARS-CoV-2 cytopathic assay with a compound collection of 8,810 approved and investigational drugs, mechanism-based bioactive compounds, and natural products. Three hundred and nineteen compounds with anti-SARS-CoV-2 activities were identified and confirmed, including 91 approved drugs and 49 investigational drugs. The anti-SARS-CoV-2 activities of 230 of these confirmed compounds, of which 38 are approved drugs, have not been previously reported. Chlorprothixene, methotrimeprazine, and piperacetazine were the three most potent FDA-approved drugs with anti-SARS-CoV-2 activities. These three compounds have not been previously reported to have anti-SARS-CoV-2 activities, although their antiviral activities against SARS-CoV and Ebola virus have been reported. These results demonstrate that this comprehensive data set is a useful resource for drug repurposing efforts, including design of new drug combinations for clinical trials for SARS-CoV-2.

Drug Repurposing Screen for Compounds Inhibiting the Cytopathic Effect of SARS-CoV-2

Drug repurposing is a rapid approach to identifying therapeutics for the treatment of emerging infectious diseases such as COVID-19. To address the urgent need for treatment options, we carried out a quantitative high-throughput screen using a SARS-CoV-2 cytopathic assay with a compound collection of 8,810 approved and investigational drugs, mechanism-based bioactive compounds, and natural products. Three hundred and nineteen compounds with anti-SARS-CoV-2 activities were identified and confirmed, including 91 approved drug and 49 investigational drugs. Among these confirmed compounds, the anti-SARS-CoV-2 activities of 230 compounds, including 38 approved drugs, have not been previously reported. Chlorprothixene, methotrimeprazine, and piperacetazine were the three most potent FDA approved drugs with anti-SARS-CoV-2 activities. These three compounds have not been previously reported to have anti-SARS-CoV-2 activities, although their antiviral activities against SARS-CoV and Ebola virus have been reported. These results demonstrate that this comprehensive data set of drug repurposing screen for SARS-CoV-2 is useful for drug repurposing efforts including design of new drug combinations for clinical trials.

20 Years of Medicinal Chemistry – Always Look at the Bright Side (of Life)

This paper summarizes a personal perspective on key learnings from projects the author was involved in over the last 20 years. For example, the discovery of macitentan, the most successful molecule to date from this personal collection, marketed by J&J for the treatment of pulmonary arterial hypertension (PAH). [1] Then the discovery of ACT-462206, a dual orexin receptor antagonist for the treatment of insomnia disorder with a serendipitously short story from the screening hit to the drug [2] followed by the identification of daridorexant, another dual orexin receptor antagonist. Daridorexant successfully passed first pivotal phase 3 clinical trial in April 2020 for the treatment of insomnia disorder [3] ("Good things come to those who wait"). Finally, ACT-451840, an antimalarial drug with a novel mechanism of action, identified in the perfect collaboration between academia and industry. The compound is in phase 2 clinical development. [4] In addition, the importance of the screening compound collection is briefly discussed, as a key asset for drug discovery. The measures Idorsia implemented to obtain valuable hits from high-throughput screening (HTS) campaigns are elaborated. [5] Drug discovery is a multi-disciplinary business with unlimited exciting challenges asking for excessive optimism when tackling them in a playful manner.