Substituted aryl malonamates as new serine β-lactamase substrates: Structure–activity studies

Abstract

A series of substituted aryl malonamates have been prepared. These compounds are analogues of aryl phenaceturates where the amido side chain has been replaced by a retro-amide. Like the phenaceturates, these compounds are substrates of typical class A and class C β-lactamases, particularly of the latter, and of soluble DD-peptidases. The effect of substituents α to the ester carbonyl group on turnover by these enzymes is similar to that in the phenaceturates. On the other hand, N-alkylation of the side chain amide of malonamates, but not of phenaceturates, retains the susceptibility of the compounds to hydrolysis by β-lactamases. This reactivity is not enhanced, however, by bridging the amide nitrogen and Cα atoms. A phosphonate analogue of the malonamates was found to be an irreversible inhibitor of the β-lactamases. These results, therefore, provide further evidence for the covalent access of compounds bearing retro-amide side chains to the active sites of β-lactam-recognizing enzymes.