β‐Lactam antibiotics, which account for nearly 70% of all prescriptions for bacterial infections, remain the cornerstone of antimicrobial chemotherapy. However, their clinical effectiveness is increasingly compromised by the widespread emergence of β‐lactamase‐mediated resistance. These enzymes hydrolyze the β‐lactam ring through an addition–elimination mechanism, abolishing antibacterial activity. Preserving the efficacy of β‐lactam antibiotics, particularly carbapenems, regarded as the last line of defense against multidrug‐resistant (MDR) pathogens, is therefore critical. Here, we report the design and synthesis of compound 3 , a zwitterionic penicillin‐derived sulfone that integrates two key principles: enhanced permeability of zwitterionic molecules and improved inhibitory potency through (2‐pyridyl)methylene introduction within the sulbactam scaffold to achieve an adduct stable against hydrolysis. In vitro assays demonstrated that compound 3 significantly restored β‐lactam activity against MDR pathogens producing extended‐spectrum β‐lactamases (ESBLs) and carbapenem‐hydrolyzing class D β‐lactamases. It notably improved imipenem and ceftazidime efficacy against strains expressing OXA‐48 and PDC‐1, whose inhibitory capacity was determined by kinetic analysis with the isolated enzymes. Mechanistic studies using mass spectrometry and molecular dynamics simulations revealed ligand‐induced pocket formation, π‐stacking modulation, and hydrophobic engagement, supporting a covalent, water‐shielded inactivation pathway via indolizine adduct formation. The nonsterically hindered amine in 3 favored PDC‐1 binding and overall permeability while exerting a neutral effect on OXA‐48 binding. These results underscore the potential of compound 3 as a next‐generation β‐lactamase inhibitor for combating infections caused by ESBL‐ and carbapenemase‐producing Enterobacterales and Pseudomonas aeruginosa .
Rodríguez et al. (Thu,) studied this question.