The two β-carbonic anhydrases (CAs, EC 4.2.1.1) from the bacterial pathogen Salmonella enterica serovar Typhimurium, stCA 1 and stCA 2, were investigated for their inhibition with a large panel of sulfonamides and sulfamates. Unlike inorganic anions, which are weak, millimolar inhibitors of the two enzymes [Vullo et al., Bioorg. Med. Chem. Lett.2011, 21, 3591], sulfonamides and sulfamates are effective micro-to nanomolar inhibitors of the two enzymes. Various types of inhibitors have been detected among the 38 investigated sulfonamides/sulfamates, with K(I)s in the range of 31 nM-5.87 μM. The best stCA 1 inhibitors were acetazolamide and benzolamide-based compounds, whereas the best stCA 2 inhibitors were sulfonylated benzenesulfonamides and amino-benzolamide derivatives (K(I)s in the range of 31-90 nM). 3-Fluoro-5-chloro-4-aminobenzolamide showed an inhibition constant of 51 nM against stCA 1 and of 38 nM against stCA 2, being the best inhibitor detected so far for these enzymes. As many strains of S. enterica show extensive resistance to classical antibiotics, inhibition of the β-CAs investigated here may be useful for developing novel antibacterials, targeting β-CAs which may be involved in pathogenicity and invasion of some bacteria.
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