Repurposing FDA-approved sulphonamide carbonic anhydrase inhibitors for treatment of Neisseria gonorrhoeae .

Neisseria gonorrhoeae is a high-priority pathogen of concern due to the growing prevalence of resistance development against approved antibiotics. Herein, we report the anti-gonococcal activity of ethoxzolamide, the FDA-approved human carbonic anhydrase inhibitor. Ethoxzolamide displayed an MIC 50, against a panel of N. gonorrhoeae isolates, of 0.125 µg/mL, 16-fold more potent than acetazolamide, although both molecules exhibited almost similar potency against the gonococcal carbonic anhydrase enzyme (NgCA) in vitro . Acetazolamide displayed an inhibition constant ( K i ) versus NgCA of 74 nM, while Ethoxzolamide ' s K i was estimated to 94 nM. Therefore, the increased anti-gonococcal potency of ethoxzolamide was attributed to its increased permeability in N. gonorrhoeae as compared to that of acetazolamide. Both drugs demonstrated bacteriostatic activity against N. gonorrhoeae , exhibited post-antibiotic effects up to 10 hours, and resistance was not observed against both. Taken together, these results indicate that acetazolamide and ethoxzolamide warrant further investigation for translation into effective anti- N. gonorrhoeae agents.