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

Barbara Garofalo,Federica Prati,Roberta Montanari,Rosa Buonfiglio,Rosella Ombrato,Isabella Coletta,Giorgio Pochetti,Claudio Milanese,Noemi D’Atanasio,Daniele Carettoni,Valeria Wanke,Angela Molteni,Davide Capelli,Francesco Paolo Di Giorgio

doi:10.3390/ph14070612

Abstract

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.

Highlights

Angelini Pharma S.p.A., Global R&D External Innovation, Viale Amelia 70, 00181 Rome, Italy; Consiglio Nazionale delle Ricerche—Istituto di Cristallografia, Via Salaria—km 29.300, Monterotondo, Abstract: The major cause of bacterial resistance to β-lactams is the production of hydrolytic βlactamase enzymes
The combination of susceptible β-lactams with β-lactamase inhibitors (BLIs), which protect them from degradation and restore their antibacterial activity, serves
The chemical library was compiled by employing the scaffold concept to aid preliminary structure activity relationship (SAR) expansion after high-throughput screening (HTS) data analysis, besides ensuring chemical variability of the dataset

Summary

Introduction

Angelini Pharma S.p.A., Global R&D External Innovation, Viale Amelia 70, 00181 Rome, Italy; Consiglio Nazionale delle Ricerche—Istituto di Cristallografia, Via Salaria—km 29.300, Monterotondo, Abstract: The major cause of bacterial resistance to β-lactams is the production of hydrolytic βlactamase enzymes. The combination of β-lactam antibiotics with β-lactamase inhibitors (BLIs) is the main strategy for overcoming such issues. 1. Introduction β-lactams such as penicillins, cephalosporins, carbapenems, and monobactams are the most effective and extensively used class of antibacterial agents, representing approximately 65% of the prescribed antibiotics worldwide [1]. Drug-resistant bacteria produce β-lactamase enzymes that hydrolyze and inactivate the β-lactam ring [2,3,4,5], preventing the covalent inhibition of essential cell-wall biosynthesis proteins, named penicillin-binding proteins (PBPs) [6,7,8,9,10], which result in the loss of drug’s antibacterial effectiveness. The combination of susceptible β-lactams with β-lactamase inhibitors (BLIs), which protect them from degradation and restore their antibacterial activity, serves

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Conclusion