ML302, a Novel Beta-lactamase (BLA) Inhibitor

Excerpt

VIM-2 and IMP-1 are Ambler class B metallo-β-lactamases (MBL) capable of hydrolyzing a broad-spectrum of β-lactam antibiotics. Although the discovery and development of MBL inhibitors continue to be an area of active research, an array of potent, non-selective (broad-acting) small molecule inhibitors is yet to be fully characterized. Here we describe a novel dual VIM-2/IMP-1 inhibitor that exhibits efficacy in multiple clinical isolates. We therefore claim CID 53362017/SID 134220672 as a potent, broad acting VIM-2/IMP-1 probe (ML302). This compound was discovered from a medicinal chemistry effort that sought to improve the potency and efficacy of high-throughput screening (HTS) hits. During these chemistry efforts, we identified a rhodanine scaffold that exhibited activity against recombinant VIM-2 and IMP-1 in nitrocefin-based enzyme activity assays. Various secondary assays were run to determine its dual potency (VIM-2 IC₅₀ = 548 nM; IMP-1 IC₅₀ = 3.02 μM) and class B selectivity (it was inactive in TEM-1 and AmpC beta-lactamase enzymatic assays). Kinetic analyses demonstrated that ML302 behaves as a mixed mode uncompetitive/non-competitive inhibitor, with submicromolar K_i values against VIM-2 and IMP-1 (K_i = 183 ± 24 nM and 930 ± 97 nM, respectively). This represents an improvement in both our prior probe ML121 and the previously existing art compound Mitoxantrone, each of which inhibited only VIM-2. Subsequent studies revealed that this probe potentiates the activity of imipenem antibiotic in inhibiting growth of laboratory E. coli BL21 strains harboring VIM-2 and IMP-1, as well as clinical isolates YMC07 (VIM-2-containing Acinetobacter sp.), BAA-2146 (NDM-1-containing Klebsiella pneumonia), PA641 (VIM-2-containing Pseudomonas aeruginosa), and KN20 (IMP-1-containing Pseudomonas aeruginosa). This probe will serve as a valuable tool to elucidate the role of VIM-2 and IMP-1 in nosocomial beta-lactam antibiotic resistance.