|
| ||
|
|
||
CA Inhibitor (ca + inhibitor)
Selected AbstractsCarbonic Anhydrase Inhibitor Sulthiame Reduces Intracellular pH and Epileptiform Activity of Hippocampal CA3 NeuronsEPILEPSIA, Issue 5 2002Tobias Leniger Summary: ,Purpose: Sulthiame is a carbonic anhydrase (CA) inhibitor with an anticonvulsant effect in the treatment of benign and symptomatic focal epilepsy in children. The aim of the study was to elucidate the mode of action of sulthiame with respect to possible changes of intracellular pH (pHi) that might develop along with sulthiame's anticonvulsant properties. Methods: The effects of sulthiame (a) on pHi of 2,,7-bis(2-carboxyethyl)-5(6)-carboxyfluorescein-acetoxymetyl ester (BCECF-AM) loaded CA3 neurones as well as (b) on epileptiform activity (induced by 50 ,M 4-aminopyridine) were compared with those of the CA inhibitors acetazolamide and benzolamide. Results: In the majority of neurons, sulthiame (1.0,1.5 mM; n = 8) as well as the membrane permeant acetazolamide (0.5,1.0 mM; n = 6) reversibly decreased pHi by 0.18 ± 0.05 (SD) and 0.17 ± 0.10 (SD) pH units, respectively, within 10 min. The poor membrane permeant benzolamide (1.0,2.0 mM) had no influence on pHi (n = 8). Sulthiame (1.0,2.5 mM) and acetazolamide (1.0,2.0 mM) reversibly reduced the frequency of action potentials and epileptiform bursts after 10,15 min (n = 9, n = 7), whereas benzolamide (1.0,2.0 mM) had no effect (n = 6). Conclusions: The results suggest that sulthiame acts as a membrane-permeant CA inhibitor whose beneficial effect on epileptiform activity results at least in part from a modest intracellular acidosis of central neurons. [source] Functional demonstration of surface carbonic anhydrase IV activity on rat astrocytesGLIA, Issue 3 2006Nataliya Svichar Abstract Buffering of the brain extracellular fluid is catalyzed by carbonic anhydrase (CA) activity. Whereas the extracellular isoform CA XIV has been localized exclusively to neurons in the brain, and to glial cells in the retina, there has been uncertainty regarding the form or forms of CA on the surface of brain astrocytes. We addressed this issue using physiological methods on cultured and acutely dissociated rat astrocytes. Prior work showed that the intracellular lactate-induced acidification (LIA) of astrocytes is diminished by benzolamide, a poorly permeant, nonspecific CA inhibitor. We demonstrate that pretreatment of astrocytes with phosphatidylinositol-specific phospholipase C (PI-PLC) results in a similar inhibition of the mean LIA (by 66 ± 3%), suggesting that the glycosylphosphatidylinositol-anchored CA IV was responsible. Pretreatment of astrocytes with CA IV inhibitory antisera also markedly reduced the mean LIA in both cultured cortical (by 46 ± 4%) and acutely dissociated hippocampal astrocytes (by 54 ± 8%). Pre-immune sera had no effect. The inhibition produced by PIPLC or CA IV antisera was not significantly less than that by benzolamide, suggesting that the majority of detectable surface CA activity was attributable to CA IV. Thus, our data collectively document the presence of CAIV on the surface of brain astrocytes, and suggest that this is the predominant CA isoform on these cells. © 2005 Wiley-Liss, Inc. [source] Therapeutic applications of glycosidic carbonic anhydrase inhibitorsMEDICINAL RESEARCH REVIEWS, Issue 3 2009Jean-Yves Winum Abstract The zinc enzymes carbonic anhydrases (CAs, EC 4.2.1.1) are very efficient catalysts for the reversible hydration of carbon dioxide to bicarbonate and hence play an important physiological role. In humans, 16 different isozymes have been described, some of them being involved in various pathological disorders. Several of these isozymes are considered as drug targets, and the design of selective inhibitors is a long-standing goal that has captured the attention of researchers for 40 years and has lead to clinical applications against different pathologies such as glaucoma, epilepsy, and cancer. Among the different strategies developed for designing selective CA inhibitors (CAIs), the "sugar approach" has recently emerged as a new attractive and versatile tool. Incorporation of glycosyl moieties in different aromatic/heterocyclic sulfonamide/sulfamides/sulfamates scaffolds has led to the development of numerous and very effective inhibitors of potential clinical value. The clinical use of a highly active carbohydrate-based CA inhibitor, i.e., topiramate, constitutes an interesting demonstration of the validity of this approach. Other carbohydrate-based compounds also demonstrate promising potential for the treatment of ophthalmologic diseases. This review will focus on the development of this emerging sugar-based approach for the development of CAIs. © 2008 Wiley Periodicals, Inc. Med Res Rev, 29, No. 3, 419-435, 2009 [source] High-resolution structure of human carbonic anhydrase II complexed with acetazolamide reveals insights into inhibitor drug designACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 10 2009Katherine H. Sippel The crystal structure of human carbonic anhydrase II (CA II) complexed with the inhibitor acetazolamide (AZM) has been determined at 1.1,Å resolution and refined to an Rcryst of 11.2% and an Rfree of 14.7%. As observed in previous CA II,inhibitor complexes, AZM binds directly to the zinc and makes several key interactions with active-site residues. The high-resolution data also showed a glycerol molecule adjacent to the AZM in the active site and two additional AZMs that are adventitiously bound on the surface of the enzyme. The co-binding of AZM and glycerol in the active site demonstrate that given an appropriate ring orientation and substituents, an isozyme-specific CA inhibitor may be developed. [source] Cyclodextrin complexes of sulfonamide carbonic anhydrase inhibitors as long-lasting topically acting antiglaucoma agentsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 10 2002Francesca Maestrelli Abstract Complexes of several 1,3,4-thiadiazole-2-sulfonamide derivatives possessing strong carbonic anhydrase (CA) inhibitory properties with ,-cyclodextrin and hydroxypropyl-,-cyclodextrin were obtained and characterized. Although the investigated CA inhibitors possessed very powerful inhibitory properties against the two CA isozymes involved in aqueous humor production within the eye, i.e., CA II and CA IV, these compounds were topically ineffective as intraocular pressure (IOP) lowering agents in normotensive/hypertensive rabbits, due to their very low water solubility. On the contrary, the cyclodextrin,sulfonamide complexes proved to be effective and long-lasting IOP lowering agents in the two animal models of glaucoma mentioned above. © 2002 Wiley-Liss Inc. and the American Pharmaceutical Association J Pharm Sci 91:2211,2219, 2002 [source] Therapeutic applications of glycosidic carbonic anhydrase inhibitorsMEDICINAL RESEARCH REVIEWS, Issue 3 2009Jean-Yves Winum Abstract The zinc enzymes carbonic anhydrases (CAs, EC 4.2.1.1) are very efficient catalysts for the reversible hydration of carbon dioxide to bicarbonate and hence play an important physiological role. In humans, 16 different isozymes have been described, some of them being involved in various pathological disorders. Several of these isozymes are considered as drug targets, and the design of selective inhibitors is a long-standing goal that has captured the attention of researchers for 40 years and has lead to clinical applications against different pathologies such as glaucoma, epilepsy, and cancer. Among the different strategies developed for designing selective CA inhibitors (CAIs), the "sugar approach" has recently emerged as a new attractive and versatile tool. Incorporation of glycosyl moieties in different aromatic/heterocyclic sulfonamide/sulfamides/sulfamates scaffolds has led to the development of numerous and very effective inhibitors of potential clinical value. The clinical use of a highly active carbohydrate-based CA inhibitor, i.e., topiramate, constitutes an interesting demonstration of the validity of this approach. Other carbohydrate-based compounds also demonstrate promising potential for the treatment of ophthalmologic diseases. This review will focus on the development of this emerging sugar-based approach for the development of CAIs. © 2008 Wiley Periodicals, Inc. Med Res Rev, 29, No. 3, 419-435, 2009 [source] Sulfamates and their therapeutic potentialMEDICINAL RESEARCH REVIEWS, Issue 2 2005Jean-Yves Winum Abstract Starting from the very simple molecule sulfamic acid, O -substituted-, N -substituted-, or di-/tri-substituted sulfamates may be obtained, which show specific biological activities which were or started to be exploited for the design of many types of therapeutic agents. Among them, sulfamate inhibitors of aminoacyl-tRNA synthetases (aaRSs) were recently reported, constituting completely new classes of antibiotics, useful in the fight of drug-resistant infections. Anti-viral agents incorporating sulfamate moieties have also been obtained, with at least two types of such derivatives investigated: the nucleoside/nucleotide human immunodeficiency virus (HIV) reverse transcriptase inhibitors, and the HIV protease inhibitors (PIs). In the increasing armamentarium of anti-cancer drugs, the sulfamates occupy a special position, with at least two important targets evidenced so far: the steroid sulfatases (STSs) and the carbonic anhydrases (CAs). An impressing number of inhibitors of STSs of the sulfamate type have been reported in the last years, with several compounds, such as 667COUMATE among others, progressing to clinical trials for the treatment of hormone-dependent tumors (breast and prostate cancers). This field is rapidly evolving, with many types of new inhibitors being constantly reported and designed in such a way as to increase their anti-tumor properties, and decrease undesired features (for example, estrogenicity, a problem encountered with the first generation such inhibitors, such as EMATE). Among the many isozymes of CAs, at least two, CA IX and CA XII, are highly overexpressed in tumors, being generally absent in the normal tissues. Inhibition of tumor-associated CAs was hypothesized to lead to novel therapeutic approaches for the treatment of cancer. Many sulfamates act as very potent (low nanomolar) CA inhibitors. The X-ray crystal structure of the best-studied isozyme, CA II, with three sulfamates (sulfamic acid, topiramate, and EMATE) has recently been reported, which allowed for a rationale drug design of new inhibitors. Indeed, low nanomolar CA IX inhibitors of the sulfamate type have been reported, although such compounds also act as efficient inhibitors of isozymes CA I and II, which are not associated with tumors. A large number of anti-convulsant sulfamates have been described, with one such compound, topiramate, being widely used clinically as anti-epileptic drug. By taking into consideration a side effect of topiramate, an anti-epileptic drug leading to weight loss in some patients, it has recently been proposed to use this drug and related sulfamates for the treatment of obesity. The rationale of this use is based on the inhibition of the mitochondrial CA isozyme, CA V, involved in lipogenesis. Some sulfamates were also shown to possess potent inhibitory activity against acyl coenzyme A:cholesterol acyltransferase, an enzyme involved in cholesterol metabolism. One such agent, avasimibe, is in advanced clinical trials for the treatment of hyperlipidemia and atherosclerosis. Thus, the sulfamate moiety offers very attractive possibilities for the drug design of various pharmacological agents, which are on one hand due to the relative ease with which such compounds are synthesized, and on the other one, due to the fact that biological activity of most of them is impressive. © 2004 Wiley Periodicals, Inc. [source] | ||||||||||