Covalent Inhibition of Serine β-Lactamases by Novel Hydroxamic Acid Derivatives

The effectiveness of β-lactam antibiotics is greatly limited by the ability of bacteria to produce β-lactamases. These enzymes catalyze the hydrolysis of β-lactams and thus loss of their antibiotic activity. The search for inhibitors of β-lactamases began soon after β-lactams were introduced into medical practice and continues today. Some time ago, we introduced a new class of covalent serine β-lactamase inhibitors, the O-aryloxycarbonyl hydroxamates, that inactivated these enzymes by a unique mechanism in which the active site became cross-linked. We describe in this paper some new variants of this class of inhibitor. First, we investigated compounds in which more polar hydroxamates were incorporated. These were generally not more active than the original compounds against representative class A and class C β-lactamases, but one of them, 1-(benzoyl)-O-(phenoxycarbonyl)-3-hydroxyurea, was significantly more stable in solution, thus revealing a useful platform for further design. Second, we describe a seri...