Multiligand approach to the identification of resistant strains overexpressing beta-lactamase

β-Lactamases (BLs) are among the main responsible of the threatening spread of Gram- negative pathogens resistant to available antibiotics, including last resort carbapenems. [1-2] The rapid detection of resistant BLs responsible of bacterial infections represents a critical challenge for the choice of the most appropriate therapy. As a consequence approaches aiming at the identification of new antibacterial agents or at the identification of the organisms conferring resistance in bacterial infections are strictly connected. Phenyl-boronic acids have been identified as valuable compounds preventing beta-lactam antibiotics hydrolysis by BLs and therefore prolonging antibiotics antimicrobial action. Diagnostic applications of boronic acids were previously foreseen highlighting the limited efficacy of a single boronic compound in the BLs detection: to reliably characterize each BL in the cellular environment a panel of molecules is needed. [3-5] In the present work we propose the inhibitory activity characterization of a benzen-boronic acids set against a selected panel of therapeutically relevant Extended Spectrum Beta-Lactamases (ESBLs). A multi-ligand approach is applied to BLs detection representing an improvement in the reliable recognition of a specific target enzyme: it relies on the differential profile of a selected inhibitor’s set against each considered BL in a panel of ESBLs. The exploited strategy includes covalent molecular docking, screening, synthetic chemistry, enzyme inhibition kinetic and cellular studies on clinical isolates. The inhibitory profile of the benzene-boronic acids compounds set against resistant bacteria overexpressing serine- and metallo- ESBLs belonging to class A, B, C and D has been obtained. Among the developed boronic acids set, one compound was able to potentiate cefotaxime against KPC-2 carbapenemase with a MIC value reduction of 32 fold, presenting an interesting antibacterial activity against NDM-1 and VIM-2 overexpressing resistant bacteria as well (32-fold improvement). [6] The obtained results open the way to the potential use of our selected compounds set as diagnostic tool for timely BLs detection.