Carbonic anhydrase inhibitors:: DNA cloning and inhibition studies of the α-carbonic anhydrase from Helicobacter pylori, a new target for developing sulfonamide and sulfamate gastric drugs

We have cloned and sequenced Helicobacter pylori alpha-class carbonic anhydrase (hpCA) from patients with different gastric mucosal lesions, including gastritis (n = 15), ulcer (n = 6), and cancer (n = 16). Although several polymorphisms were newly identified such as (12)Ala, (13)Thr, (16)Ile, and (168)Phe, there was no significant relevance of any polymorphism with gastric mucosal lesion types. A library of sulfonamides/sulfamates has been investigated for the inhibition of hpCA, whereas new derivatives have been obtained by attaching 4-tert-butyl-phenylcarboxamido/sulfonamido tails to benzenesulfonamide/1,3,4-thiadiazole-2-sulfonamide scaffolds. All types of activity for inhibition of hpCA have been detected. Dorzolamide and simple 4-substituted benzenesulfonamides were weak inhibitors (K-I 873-4360 nM). Sulfanilamide, orthanilamide, some of their derivatives, and indisulam showed better activity (K-I 413-640 nM), whereas most of the clinically used inhibitors, such as methazolamide, ethoxzolamide, dichlorophenamide, brinzolamide, topiramate, zonisamide, etc., acted as medium-potency inhibitors (K-I 105-378 nM). Some potent hpCA inhibitors were detected too (K-I 12-84 nM) among acetazolamide, 4-amino-6-chloro-1,3-benzenedisulfonamide and some newly designed compounds incorporating lipophilic tails. Some of the newly prepared derivatives had selectivity ratios for inhibiting hpCA over hCA II in the range of 1.25-3.48, showing thus some selectivity for inhibiting the bacterial enzyme. Since hpCA is essential for the survival of the pathogen in acid, it might be used as a new pharmacologic tool in the management of drug-resistant H. pylori.