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

Abstract

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 12Ala, 13Thr, 16Ile, and 168Phe, 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 (KI 873-4360 nM). Sulfanilamide, orthanilamide, some of their derivatives, and indisulam showed better activity (KI 413-640 nM), whereas most of the clinically used inhibitors, such as methazolamide, ethoxzolamide, dichlorophenamide, brinzolamide, topiramate, zonisamide, etc., acted as medium-potency inhibitors (KI 105-378 nM). Some potent hpCA inhibitors were detected too (KI 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.

Cloning, purification and preliminary crystallographic analysis of the complex ofHelicobacter pyloriα-carbonic anhydrase with acetazolamide

“…As with CAs from other species, Hp CA is inhibited by sulfonamides, particularly by the anti-glaucoma drug acetazolamide (2-acetylamido-1,3,4-thiadiazole-5-sulfonamide; Chirica et al, 2002;Nishimori et al, 2006). Previous studies have shown that treating H. pylori with CA inhibitors drastically reduces the ability of the bacteria to survive within an acid environment, suggesting that CAs are essential for colonization of the stomach and duodenum Bury-Moné et al, 2008).…”

Inhibition of Carbonic Anhydrase II by Thioxolone: A Mechanistic and Structural Study

“…Other uses being explored include treatment of osteoporosis and as a diagnostic tool in magnetic resonance imaging (MRI) and photon emission tomography (PET) (25). Furthermore, other R-class CA isozymes that may be therapeutically targeted by CA inhibitors are found in the prokaryotic mammalian pathogens Neisseria gonorrheae, (28)(29)(30) Helicobacter pylori (31)(32)(33), and the eukaryotic malarial parasite Plasmodium falciparum (34)(35)(36). Known R-CA inhibitors include various anions, imidazole, phenol, hydroxyurea, carboxylates, organic phosphates and phosphonates, and various sulfonamide compounds (R-C-SO 2 NH 2 ) (4,11,25).…”

Inhibition of Bacterial Carbonic Anhydrases as a Novel Approach to Escape Drug Resistance

“…This pathogenic bacterium lives in the highly acidic environment of the stomach (pH = 2-3). Its genome encodes three CAs: one α-, one β-, and one γ-CA, respectively [66][67][68][69][70]. The α-CA was shown to possess a periplasmic localization, the β-CA has been found in the cytoplasm, whereas no information is available on the expression/localization of the H. pylori γ-CA.…”

“…[103,104] Sulfanilamide, orthanilamide, some of their derivatives, and indisulam showed better activity (K(I)s in the range of 310-562 nM), whereas most of the clinically used CA inhibitors, such as methazolamide, ethoxzolamide, dichlorophenamide, brinzolamide, topiramate, zonisamide, etc., acted as medium potency hpCA inhibitors (K(I)s in the range of 124-287 nM) [70] .Some potent hpCA inhibitors were detected too (K(I)s in the range of 20-96 nM) such as acetazolamide, 4-amino-6-chloro-1,3-benzenedisulfonamide, 4-sulfanilyl-aminoethylbenzenesulfonamide, and 4-(2-amino-pyrimidin-4-yl)-benzenesulfonamide [70] .…”