4-Amino-1,2,4-triazole-3-thione as a Promising Scaffold for the Inhibition of Serine and Metallo-\u3b2-Lactamases

The emergence of bacteria that co-express serine- and metallo- carbapenemases is a threat to the efficacy of the available \u3b2-lactam antibiotic armamentarium. The 4-amino-1,2,4-triazole-3-thione scaffold has been selected as the starting chemical moiety in the design of a small library of \u3b2-Lactamase inhibitors (BLIs) with extended activity profiles. The synthesised compounds have been validated in vitro against class A serine \u3b2 12Lactamase (SBLs) KPC-2 and class B1 metallo \u3b2 12Lactamases (MBLs) VIM-1 and IMP-1. Of the synthesised derivatives, four compounds showed cross-class micromolar inhibition potency and therefore underwent in silico analyses to elucidate their binding mode within the catalytic pockets of serine- and metallo-BLs. Moreover, several members of the synthesised library have been evaluated, in combination with meropenem (MEM), against clinical strains that overexpress BLs for their ability to synergise carbapenems