Routes of Synthesis of Carbapenems for Optimizing Both the Inactivation of L,D-Transpeptidase LdtMt1 of Mycobacterium tuberculosis and the Stability toward Hydrolysis by β-Lactamase BlaC.

Abstract

Combinations of β-lactams of the carbapenem class, such as meropenem, with clavulanate, a β-lactamase inhibitor, are being evaluated for the treatment of drug-resistant tuberculosis. However, carbapenems approved for human use have never been optimized for inactivation of the unusual β-lactam targets of Mycobacterium tuberculosis or for escaping to hydrolysis by broad-spectrum β-lactamase BlaC. Here, we report three routes of synthesis for modification of the two side chains carried by the β-lactam and the five-membered rings of the carbapenem core. In particular, we show that the azide-alkyne Huisgen cycloaddition reaction catalyzed by copper(I) is fully compatible with the highly unstable β-lactam ring of carbapenems and that the triazole ring generated by this reaction is well tolerated for inactivation of the L,D-transpeptidase LdtMt1 target. Several of our new carbapenems are superior to meropenem both with respect to the efficiency of in vitro inactivation of LdtMt1 and reduced hydrolysis by BlaC.