Revisiting amifostine as a potential NDM-1 inhibitor for combatting bacteria resistance

The global epidemic of NDM-1-producing gram-negative pathogens has significantly undermined the clinical efficacy of carbapenems, exacerbating the issue of bacterial resistance. Consequently, the development of novel inhibitor that can inhibit NDM-1 has been prompted to address the infections it causes. In this study, we redefined amifostine (AMI), which exhibits a 50 % inhibitory concentration (IC₅₀) of 25.4 ± 0.6 μM and significantly inhibits the hydrolytic activity of NDM-1 in a dose-dependent manner, suggesting its potential as an NDM-1 inhibitor. In vitro, AMI effectively restored the antibacterial activity of Meropenem (MEM) against NDM-1 positive E. coli, resulting in a four-fold decrease in MIC of MEM from 64 μg/mL to 16 μg/mL. The combination of AMI and MEM exhibited significant synergy, as indicated by FICI index of 0.375. In vivo, the synergistic therapeutic effect of AMI and MEM was assessed in mice infected with NDM-1 positive E. coli. Compared to the control group, the combination of AMI and MEM significantly enhanced the survival rate of infected mice and reduced both the bacterial burden and the inflammatory response associated with NDM-1-positive E. coli, also alleviated histopathological damage in these mice. Finally, it was demonstrated that AMI could promote the penetration of bacterial cell membrane into the cell by changing the permeability of bacterial cell membrane. Further molecular dynamics simulations and molecular interaction analysis showed that AMI could form stable hydrogen bonds with key amino acid residues in the active pocket of NDM-1, including Asn220, Gln123 and Glu152, thereby competitively inhibiting the meropenem hydrolysis activity of NDM-1. This study presents a novel framework for the development of NDM-1 inhibitors, offering a new strategy to combat infections caused by drug-resistant bacteria.