Carbonic anhydrase inhibitors. Inhibition and homology modeling studies of the fungal β-carbonic anhydrase from Candida albicans with sulfonamides

The beta-carbonic anhydrase (CA, EC 4.2.1.1) from the fungal pathogen Candida albicans (Nce103) is involved in a CO(2) sensing pathway critical for the pathogen life cycle and amenable to drug design studies. Herein we report an inhibition study of Nce103 with a library of sulfonamides and one sulfamate, showing that Nce103, similarly to the related enzyme from Cryptococcus neoformans Can2, is inhibited by these compounds with K(I)s in the range of 132 nM-7.6 microM. The best Nce103 inhibitors were acetazolamide, methazolamide, bromosulfanilamide, and 4-hydroxymethylbenzenesulfonamide (K(I)s<500 nM). A homology model was generated for Nce103 based on the crystal structure of Can2. The model shows that compounds with zinc-binding groups incorporating less polar moieties and compact scaffolds generate stronger Nce103 inhibitors, whereas highly polar zinc-binding groups and bulkier compounds appear more promising for the specific inhibition of Can2. Such compounds may be useful for the design of antifungal agents possessing a new mechanism of action.