A practical electrochemical method for determining the inhibitory activity of New Delhi Metallo-β-lactamase-1 inhibitors

A practical electrochemical method for the determination of the inhibitory activity of New Delhi metallo-β-lactamase-1 (NDM-1) inhibitors was established with a bare pencil graphite electrode (PGE) as the working electrode and imipenem as the substrate. To validate the method, the well-known NDM-1 inhibitors EDTA and L -captopril were selected for the corresponding assays with IC 50 values of 1.22 ± 0.20 μM and 22.92 ± 1.19 μM, respectively. These results were consistent with those (5.48 ± 0.32 μM for EDTA and 69.13 ± 6.01 μM for L- captopril) from the UV–vis high-throughput assay method. Further investigation regarding the steady kinetics of a typical competitive inhibitor of L -captopril showed that the two methods provided K i values at the same level, i.e., they are 41.5 ± 3.8 μM (DPV-PGE) and 52.5 ± 2.5 μM (UV–vis), respectively.