Assay for drug discovery: Synthesis and testing of nitrocefin analogues for use as β-lactamase substrates

We report on the synthesis of three nitrocefin analogues and their evaluation as substrates for the detection of p-lactamase activity. These compounds are hydrolyzed by all four Ambler classes of beta-lactamases. Kinetic parameters were determined with eight different p-lactamases, including VIM-2, NDM-1, KPC-2, and SPM-1. The compounds do not inhibit the growth of clinically important antibiotic-resistant gram-negative bacteria in vitro. These chromogenic compounds have a distinct absorbance spectrum and turn purple when hydrolyzed by p-lactamases. One of these compounds, UW154, is easier to synthesize from commercial starting materials than nitrocefin and should be significantly less expensive to produce. (C) 2015 Elsevier Inc. All rights reserved.