The key regulatory metabolic enzyme, biotin protein ligase
(BPL),
is an attractive target for the development of novel antibiotics against
multi-drug-resistant bacteria, such as Staphylococcus aureus. Here we report the synthesis and assay of a new series of inhibitors
(6–9) against S. aureus BPL (SaBPL), where a component sulfonamide
linker was used to mimic the acyl-phosphate group of the natural intermediate
biotinyl-5′-AMP (1). A pivotal correlation between
the acidity of the central NH of the sulfonamide linker of 6–9 and in vitro inhibitory activity
against SaBPL was observed. Specifically, sulfonylcarbamate 8, with its highly acidic sulfonyl central NH, as evaluated
by 1H NMR spectroscopy, showed exceptional potency (K
i = 10.3 ± 3.8 nM). Furthermore, three
inhibitors demonstrated minimum inhibitory concentrations of 16–32
μg/mL against clinical methicillin-resistant S. aureus (MRSA) strains.