Modulation of carbonic anhydrase activity and its applications in therapy

Dual targeting carbonic anhydrase inhibitors as promising therapeutic approach: a structural overview

The dual-target inhibitor strategy is an evolving approach that holds great potential for treating complex diseases by addressing their multifactorial nature. It can enhance therapeutic outcomes, reduce side effects and avoid the emergence of drug resistance, particularly in conditions like cancer, inflammation and neurological disorders, where multiple pathways contribute to disease progression. Identifying suitable targets for a dual inhibitor approach requires a deep understanding of disease biology, knowledge of critical pathways, and selection of complementary or synergistic targets. Human carbonic anhydrases (hCAs) have been recognized as suitable drug targets for this therapeutic approach. These enzymes play a key role in maintaining pH balance, ion transport, and fluid regulation across various tissues and organs and their dysregulation has been associated to a variety of human pathologies. Consequently, the inhibition of hCAs combined to the possibility to modulate the activity of a second molecular target represents a promising way for developing more effective drugs. In this mini-review, we aim to present an overview of the most significant structural results related to the development of novel therapeutics employing hCA inhibitors as dual-targeting compounds for the treatment of complex diseases.

Thiosemicarbazone-benzenesulfonamide Derivatives as Human Carbonic Anhydrases Inhibitors: Synthesis, Characterization, and In silico Studies

INTRODUCTION

Carbonic anhydrases (CAs) are widespread metalloenzymes with the core function of catalyzing the interconversion of CO2 and HCO3 -. Targeting these enzymes using selective inhibitors has emerged as a promising approach for the development of novel therapeutic agents against multiple diseases.

METHODS

A series of novel thiosemicarbazone-containing derivatives were synthesized, characterized, and tested for their inhibitory activity against pharmaceutically important human CA I (hCA I), II (hCA II), IX (hCA IX), and XII (hCA XII) using the single tail approach.

RESULTS

The compounds generally inhibited the isoenzymes at low nanomolar concentrations, with compound 6b having Ki values of 7.16, 0.31, 92.5, and 375 nM against hCA I, II, IX and XII, respectively. Compound 6e exhibited Ki values of 27.6, 0.34, 872, and 94.5 nM against hCA I, II, IX and XII, respectively.

CONCLUSION

To rationalize the inhibition data, molecular docking studies were conducted, providing insight into the binding mechanisms, molecular interactions, and selectivity of the compounds towards the isoenzymes.

1,5-Benzodiazepines as a platform for the design of carbonic anhydrase inhibitors

A series of novel N-triazolo-benzene sulfonamides-1,5-benzodiazepines 9a-d and 10d were designed and prepared through the copper-catalyzed azide alkyne cycloaddition click chemistry procedure, reacting the N₁ -propargyl-1,5-benzodiazepine 2 and the N₁ ,N₅ -dipropargyl analog 6 with various benzene sulfonamide azides 8a-d. The synthesized compounds were found to show nanomolar affinity toward relevant isoforms of human carbonic anhydrase such as hCA I, II, IV, VII, IX, and XII. The divalent derivative 10d showed a particularly high inhibitory activity against all hCA isoforms when compared with acetazolamide, and showed potent multivalent effects, better than reported previously for divalent CA inhibitors.

Anti-breast cancer action of carbonic anhydrase IX inhibitor 4-[4-(4-Benzo[1,3]dioxol-5-ylmethyl-piperazin-1-yl)-benzylidene-hydrazinocarbonyl]-benzenesulfonamide (BSM-0004): in vitro and in vivo studies

Anti-breast cancer action of novel human carbonic anhydrase IX (hCA IX) inhibitor BSM-0004 has been investigated using in vitro and in vivo models of breast cancer. BSM-0004 was found to be a potent and selective hCA IX inhibitor with a Ki value of 96 nM. In vitro anticancer effect of BSM-0004 was analysed against MCF 7 and MDA-MA-231 cells, BSM-0004 exerted an effective cytotoxic effect under normoxic and hypoxic conditions, inducing apoptosis in MCF 7 cells. Additionally, this compound significantly regulates the expression of crucial biomarkers associated with apoptosis. The investigation was extended to confirm the efficacy of this hCA IX inhibitor against in vivo model of breast cancer. The results specified that the treatment of BSM-0004 displayed an effective in vivo anticancer effect, reducing tumour growth in a xenograft cancer model. Hence, our investigation delivers an effective anti-breast cancer agent that engenders the anticancer effect by inhibiting hCA IX.

Synthesis of new series of thiazol-(2(3H)-ylideneamino)benzenesulfonamide derivatives as carbonic anhydrase inhibitors

Human carbonic anhydrase I and II isoenzymes (hCA I and II) are important metabolic enzymes. In this study, a new series of thiazol-(2(3H)-ylideneamino)benzenesulfonamide derivatives were synthesized and also some inhibition parameters including IC50 (hydratese) and inhibition constant values (Ki , esterase) were determined. All studied compounds exhibited potent inhibition against these enzymes. They inhibited carbonic anhydrases (CAs) with the IC50 values of 113 to 395.8 nM (Ki  = 77.38-319.59 nM) for hCA I and 91.9 to 516 nM (Ki  = 62.79-425.89 nM) for hCA II. Among the compounds, 5c was found to be the most active one (Ki : 77.38 nM) for hCA I and 5g was found for hCA II with the value of 62.79 nM.

Evaluation of some thiophene-based sulfonamides as potent inhibitors of carbonic anhydrase I and II isoenzymes isolated from human erythrocytes by kinetic and molecular modelling studies

BACKGROUND

Thiophene(s) are an important group in therapeutic applications, and sulfonamides are the most important class of carbonic anhydrase (CA) inhibitors. In this study, inhibition effects of some thiophene-based sulfonamides on human erythrocytes carbonic anhydrase I and II isoenzymes (hCA-I and hCA-II) were investigated. Thiophene-based sulfonamides used in this study showed potent inhibition effect on both isoenzymes at very small concentrations.

MATERIALS AND METHODS

We report on the purification of the carbonic anhydrase I and II isoenzymes (hCA-I and hCA-II) using affinity chromatography method. The inhibition effect of the thiophene-based sulfonamides was determined by IC₅₀ and K_i parameters. A molecular docking study was performed for each molecule.

RESULTS

Thiophene-based sulfonamides showed IC₅₀ values of in the range of 69 nM to 70 µM against hCA-I, 23.4 nM to 1.405 µM against hCA-II. K_i values were in the range of 66.49 ± 17.15 nM to 234.99 ± 15.44 µM against hCA-I, 74.88 ± 20.65 nM to 38.04 ± 12.97 µM against hCA-II. Thiophene-based sulfonamides studied in this research showed noncompetitive inhibitory properties on both isoenzymes. To elucidate the mechanism of inhibition, a molecular docking study was performed for molecules 1 and 4 exhibiting a strong inhibitory effect on hCA-I and hCA-II. The compounds inhibit the enzymes by interacting out of catalytic active site. The sulfonamide and thiophene moiety played a significant role in the inhibition of the enzymes.

CONCLUSION

We hope that this study will contribute to the design of novel thiophene-based sulfonamide derived therapeutic agents that may be carbonic anhydrase inhibitors in inhibitor design studies.

Progress in the development of human carbonic anhydrase inhibitors and their pharmacological applications: Where are we today?

Carbonic anhydrases (CAs, EC 4.2.1.1) are widely distributed metalloenzymes in both prokaryotes and eukaryotes. They efficiently catalyze the reversible hydration of carbon dioxide to bicarbonate and H⁺  ions and play a crucial role in regulating many physiological processes. CAs are well-studied drug target for various disorders such as glaucoma, epilepsy, sleep apnea, and high altitude sickness. In the past decades, a large category of diverse families of CA inhibitors (CAIs) have been developed and many of them showed effective inhibition toward specific isoforms, and effectiveness in pathological conditions in preclinical and clinical settings. The discovery of isoform-selective CAIs in the last decade led to diminished side effects associated with off-target isoforms inhibition. The many new classes of such compounds will be discussed in the review, together with strategies for their development. Pharmacological advances of the newly emerged CAIs in diseases not usually associated with CA inhibition (neuropathic pain, arthritis, cerebral ischemia, and cancer) will also be discussed.

Morin attenuates ifosfamide-induced neurotoxicity in rats via suppression of oxidative stress, neuroinflammation and neuronal apoptosis

Ifosfamide (IFA), a commonly used chemotherapeutic drug, has been frequently associated with encephalopathy and central nervous system toxicity. The present study aims to investigate whether morin could protect against acute IFA-induced neurotoxicity. Morin was administered to male rats once daily for 2 consecutive days at doses of 100 and 200 mg/kg body weight (BW) orally. IFA (500 mg/kg BW; i.p.) was administered on second day. The results showed that morin markedly inhibited the production of acetylcholinesterase (AChE), butrylcholinesterase (BChE), carbonic anhydrase (CA), glial fibrillary acidic protein (GFAP), brain-derived neurotrophic factor (BDNF) and nuclear factor erythroid 2-related factor 2 (Nrf-2) induced by IFA. Morin ameliorated IFA-induced lipid peroxidation, glutathione (GSH) depletion, and decrease antioxidant enzyme activities, catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx). Histopathological changes and immunohistochemical expressions of c-Jun N-terminal kinase (JNK) and c-Fos in the IFA-induced brain tissues were decreased after administration of morin. Furthermore, morin was able to down regulate the levels of inflammatory and apoptotic markers such as nuclear factor kappa B (NF-κB), neuronal nitric oxide synthase (nNOS), tumor necrosis factor-α (TNF-α), p53, cysteine aspartate specific protease-3 (caspase-3) and B-cell lymphoma-2 (Bcl-2). Taken together, our results demonstrated that morin elicited a typical chemoprotective effect on IFA-induced acute neurotoxicity.

Synthesis and evaluation of new benzodioxole-based dithiocarbamate derivatives as potential anticancer agents and hCA-I and hCA-II inhibitors

In the current work, new benzodioxole-based dithiocarbamate derivatives were synthesized via the reaction of N-(1,3-benzodioxol-5-ylmethyl)-2-chloroacetamide with appropriate sodium salts of N,N-disubstituted dithiocarbamic acids. These derivatives were evaluated for their cytotoxic effects on A549 human lung adenocarcinoma and C6 rat glioma cell lines. N-(1,3-Benzodioxol-5-ylmethyl)-2-[4-(4-nitrophenyl)-1-piperazinylthiocarbamoylthio]acetamide (10) can be identified as the most promising anticancer agent against C6 cell line due to its notable inhibitory effect on C6 cells with an IC₅₀ value of 23.33 ± 7.63 μg/mL when compared with cisplatin (IC₅₀ = 19.00 ± 5.29 μg/mL). On the other hand, compound 10 did not show any significant cytotoxic activity against A549 cell line. The compounds were also tested for their in vitro inhibitory effects on hCA-I and hCA-II. Generally, the tested compounds were more effective on CAs than acetazolamide, the reference agent. Among these compounds, N-(1,3-benzodioxol-5-ylmethyl)-2-[(morpholinyl)thiocarbamoylthio]acetamide (3) and N-(1,3-benzodioxol-5-ylmethyl)-2-[(thiomorpholinyl)thiocarbamoylthio]acetamide (4) were found to be the most effective compounds on hCA-I with IC₅₀ values of 0.346 nM and 0.288 nM, and hCA-II with IC₅₀ values of 0.287 nM and 0.338 nM, respectively.

Betulinic acid derived hydroxamates and betulin derived carbamates are interesting scaffolds for the synthesis of novel cytotoxic compounds

The betulinic acid-derived hydroxamates 5-18, the amides 19-24, and betulin-derived bis-carbamates 25-28 as well as the carbamates 31-40 and 44-48 were prepared and evaluated for their antiproliferative activity in a photometric sulforhodamine B (SRB) assay against several human cancer cell lines and nonmalignant mouse fibroblasts (NIH 3T3). While for 3-O-acetyl hydroxamic acid 5 EC50 values as low as EC50 = 1.3 μM were found, N,O-bis-alkyl substituted hydroxamates showed lowered cytotoxicity (EC50 = 16-20 μM). In general, hydroxamic acid derivatives showed only reduced selectivity for tumor cells, except for allyl substituted compound 13 (EC50 = 5.9 μM for A2780 human ovarian carcinoma cells and EC50 > 30 μM for nonmalignant mouse fibroblasts). The cytotoxicity of betulinic acid derived amides 19-24 and of betulin derived bis-carbamates 25-28 was low, except for N-ethyl substituted 25. Hexyl substituted 39 showed EC50 = 5.6 μM (518A2 cells) while for mouse fibroblasts EC50 > 30 was determined.

Malaria parasite carbonic anhydrase: inhibition of aromatic/heterocyclic sulfonamides and its therapeutic potential

Plasmodium falciparum (P. falciparum) is responsible for the majority of life-threatening cases of human malaria, causing 1.5-2.7 million annual deaths. The global emergence of drug-resistant malaria parasites necessitates identification and characterization of novel drug targets and their potential inhibitors. We identified the carbonic anhydrase (CA) genes in P. falciparum. The pfCA gene encodes anα-carbonic anhydrase, a Zn(2+)-metalloenzme, possessing catalytic properties distinct from that of the human host CA enzyme. The amino acid sequence of the pfCA enzyme is different from the analogous protozoan and human enzymes. A library of aromatic/heterocyclic sulfonamides possessing a large diversity of scaffolds were found to be very good inhibitors for the malarial enzyme at moderate-low micromolar and submicromolar inhibitions. The structure of the groups substituting the aromatic-ureido- or aromatic-azomethine fragment of the molecule and the length of the parent sulfonamide were critical parameters for the inhibitory properties of the sulfonamides. One derivative, that is, 4- (3, 4-dichlorophenylureido)thioureido-benzenesulfonamide (compound 10) was the most effective in vitro Plasmodium falciparum CA inhibitor, and was also the most effective antimalarial compound on the in vitro P. falciparum growth inhibition. The compound 10 was also effective in vivo antimalarial agent in mice infected with Plasmodium berghei, an animal model of drug testing for human malaria infection. It is therefore concluded that the sulphonamide inhibitors targeting the parasite CA may have potential for the development of novel therapies against human malaria.

Cloning, characterization, and inhibition studies of a β-carbonic anhydrase from Leishmania donovani chagasi, the protozoan parasite responsible for leishmaniasis

Leishmaniasis is an infection provoked by protozoans belonging to the genus Leishmania. Among the many species and subsepecies of such protozoa, Leishmania donovani chagasi causes visceral leishmaniasis. A β-carbonic anhydrase (CA, EC 4.2.1.1) was cloned and characterized from this organism, denominated here LdcCA. LdcCA possesses effective catalytic activity for the CO2 hydration reaction, with kcat of 9.35 × 10(5) s(-1) and kcat/KM of 5.9 × 10(7) M(-1) s(-1). A large number of aromatic/heterocyclic sulfonamides and 5-mercapto-1,3,4-thiadiazoles were investigated as LdcCA inhibitors. The sulfonamides were medium potency to weak inhibitors (KI values of 50.2 nM-9.25 μM), whereas some heterocyclic thiols inhibited the enzyme with KIs in the range of 13.4-152 nM. Some of the investigated thiols efficiently inhibited the in vivo growth of Leishmania chagasi and Leishmania amazonensis promastigotes, by impairing the flagellar pocket and movement of the parasites and causing their death. The β-CA from Leishmania spp. is proposed here as a new antileishmanial drug target.

Anticancer carbonic anhydrase inhibitors: a patent review (2008 - 2013)

INTRODUCTION

Human carbonic anhydrases (EC 4.2.1.1) IX (hCA IX) and XII (hCA XII) are two tumor-associated proteins, being overexpressed in many tumors and involved in critical processes associated with cancer progression and response to therapy. Both are multi-domain proteins consisting of an extracellular catalytic domain (CA), a transmembrane portion (TM) and an intracytoplasmic (IC) segment. These domains have peculiar biochemical and physiological features. CA IX contains an additional proteoglycan-like (PG) domain at the N-terminus which constitutes a unique feature of this enzyme within the CA family.

AREAS COVERED

Starting from a brief description of the main molecular and catalytic features of both enzymes, their role in tumor physiology and their three-dimensional structure, this review describes the main classes of small molecule inhibitors, investigated between 2008 and 2013, able to inhibit these enzymes for both diagnostic and therapeutic applications.

EXPERT OPINION

A consistent number of patents on molecules able to inhibit the catalytic activity of CA IX and CA XII have been recently reported. Most patents deal with classical sulfonamide derivatives, demonstrating that introducing suitable substituents on the inhibitor scaffold, good selectivity can be obtained. However, the most impressive results are related to compounds containing novel chemotypes, such as coumarins and thiocumarins. Thus, it is expected that research in next future will be more dedicated to the development of molecules containing new chemotypes and a large number of studies in such field have already been published demonstrating the role of these enzymes in carcinogenesis and metastases formation.

Diuretics with carbonic anhydrase inhibitory action: a patent and literature review (2005 - 2013)

INTRODUCTION

The benzothiadiazines and high ceiling diuretics (hydrochlorothiazide, hydroflumethiazide, quinethazone, metolazone, chlorthalidone, indapamide, furosemide and bumetanide) contain primary sulfamoyl moieties acting as zinc-binding groups in the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). These drugs are widely used clinically and were recently shown to weakly inhibit isoforms CA I and II, but to possess stronger activity against isoforms involved in other important pathologies, for example, obesity, cancer, epilepsy and hypertension.

AREAS COVERED

The class of clinically used diuretics, with CA inhibitory properties, is the main topic of the review. A patent literature review covering the period from 2005 to 2013 is presented.

EXPERT OPINION

This section presents an overview of the patent literature in the sulfonamide diuretic field. Most of the patents deal with the combination of diuretic sulfonamide CA inhibitors with other agents useful in the management of cardiovascular diseases and obesity. Such combinations exert a better therapeutic activity compared to similar diuretics that do not inhibit CAs, raising the question of the polypharmacological and drug repositioning effects of these old drugs. These effects seem to be due to the potent inhibition of such drugs against CA isoforms present in kidneys and blood vessels, which explain both the blood pressure lowering effects as well as organ-protective activity of the drugs. An explanation of these data is provided by the fact that inhibition of the renal CAs leads to a large increase of the nitrite excretion in urine, suggesting that renal CAs are involved in nitrite reabsorption in humans. Important lessons for the drug design of sulfonamide CA inhibitors (CAIs) can be drawn from these data.

Cloning, characterization, and sulfonamide and thiol inhibition studies of an α-carbonic anhydrase from Trypanosoma cruzi, the causative agent of Chagas disease

An α-carbonic anhydrase (CA, EC 4.2.1.1) has been identified, cloned, and characterized from the unicellular protozoan Trypanosoma cruzi, the causative agent of Chagas disease. The enzyme (TcCA) has a very high catalytic activity for the CO2 hydration reaction, being similar kinetically to the human (h) isoform hCA II, although it is devoid of the His64 proton shuttle. A large number of aromatic/heterocyclic sulfonamides and some 5-mercapto-1,3,4-thiadiazoles were investigated as TcCA inhibitors. The aromatic sulfonamides were weak inhibitors (K(I) values of 192 nM to 84 μM), whereas some heterocyclic compounds inhibited the enzyme with K(I) values in the range 61.6-93.6 nM. The thiols were the most potent in vitro inhibitors (K(I) values of 21.1-79.0 nM), and some of them also inhibited the epimastigotes growth of two T. cruzi strains in vivo.

DNA cloning, characterization, and inhibition studies of an α-carbonic anhydrase from the pathogenic bacterium Vibrio cholerae

We have cloned, purified, and characterized an α-carbonic anhydrase (CA, EC 4.2.1.1) from the human pathogenic bacterium Vibrio cholerae, VchCA. The new enzyme has significant catalytic activity, and an inhibition study with sulfonamides and sulfamates led to the detection of a large number of low nanomolar inhibitors, among which are methazolamide, acetazolamide, ethoxzolamide, dorzolamide, brinzolamide, benzolamide, and indisulam (KI values in the range 0.69-8.1 nM). As bicarbonate is a virulence factor of this bacterium and since ethoxzolamide was shown to inhibit the in vivo virulence, we propose that VchCA may be a target for antibiotic development, exploiting a mechanism of action rarely considered until now.

Glycosidic carbonic anhydrase IX inhibitors: a sweet approach against cancer

Targeting tumour associated carbonic anhydrase (CA, EC 4.2.1.1) isoforms IX and XII is now considered as a pertinent approach for the development of new cancer therapeutics against hypoxic tumours. In the last period, with the help of X-ray crystallography, much progress has been achieved for the drug-design of selective CA IX inhibitors, by considering the three main structural elements that govern both potency and selectivity, that is, a zinc binding group (ZBG), an organic scaffold, and one or more side chains substituting the scaffold. The use of sugar moiety in the structure of sulfonamide-based CA inhibitors (CAIs), has allowed the discovery of very potent CA IX inhibitors able to impair the growth of both primary tumors and metastases. The search for specific CA IX inhibitors by using the sugar approach has become an important research field, leading to sulfonamides, sulfamates, sulfamides and coumarins with excellent in vitro activity and relevant potency in vivo, in animal models of cancer. This paper will review the latest development in this hot topic.

Inhibition of carbonic anhydrase IX as a novel anticancer mechanism

Carbonic anhydrases (CA, EC 4.2.1.1) catalyze the interconversion bewteen carbon dioxide and bicarbonate with generation of protons. The carbonic anhydrase isozyme IX (CA IX) is highly overexpresed in hypoxic tumors and shows very restricted expression in normal tissues. CA IX is a dimeric protein possessing very high catalytic activity for the hydration of carbon dioxide to protons and bicarbonate. Its quaternary structure is unique among members of this family of enzymes, allowing for structure-based drug design campaigns of selective inhibitors. Inhibition of CA IX with sulfonamide and/or coumarin inhibitors was recently shown to lead to a potent retardation for the growth of both primary tumors and metastases. Some fluorescent sulfonamides were shown to accumulate only in hypoxic tumor cells overexpressing CA IX, and might be used as diagnostic tools for imaging of hypoxic cancers. Sulfonamide inhibitors were also more effective in inhibiting the growth of the primary tumors when associated with irrdiation. CA IX is thus both a diagnostic and therapeutic validated target for the management of hypoxic tumors normally non-responsive to classical chemio- and radiotherapy.

Interfering with pH regulation in tumours as a therapeutic strategy

The high metabolic rate of tumours often leads to acidosis and hypoxia in poorly perfused regions. Tumour cells have thus evolved the ability to function in a more acidic environment than normal cells. Key pH regulators in tumour cells include: isoforms 2, 9 and 12 of carbonic anhydrase, isoforms of anion exchangers, Na+/HCO3- co-transporters, Na+/H+ exchangers, monocarboxylate transporters and the vacuolar ATPase. Both small molecules and antibodies targeting these pH regulators are currently at various stages of clinical development. These antitumour mechanisms are not exploited by the classical cancer drugs and therefore represent a new anticancer drug discovery strategy.

Bidentate Zinc chelators for alpha-carbonic anhydrases that produce a trigonal bipyramidal coordination geometry

A series of new zinc binding groups (ZBGs) has been evaluated kinetically on 13 carbonic anhydrase (CA) isoforms. The fragments show affinity for all isoforms with IC(50) values in the range of 2-11 microM. The crystal structure of hCA II in complex with one such fragment reveals a bidentate binding mode with a trigonal-bipyramidal coordination geometry at the Zn(2+) center. The fragment also interacts with Thr199 and Thr200 through hydrogen bonding and participates in a water network. Further development of this ZBG should increase the binding affinity leading to a structurally distinct and promising class of CA inhibitors.

Carbonic anhydrase inhibitors. The X-ray crystal structure of human isoform II in adduct with an adamantyl analogue of acetazolamide resides in a less utilized binding pocket than most hydrophobic inhibitors

We investigated the inhibitory activity of several 1,3,4-thiadiazole-sulfonamides against all catalytically active CA (EC 4.2.1.1), CA I-XV. The tail derivatizing the 5-position in the 1,3,4-thiadiazole-2-sulfonamide scaffold was observed to be critical as an inhibitory determinant of these compounds. The high resolution X-ray crystal structure of hCA II in complex with 5-(1-adamantylcarboxamido)-1,3,4-thiadiazole-2-sulfonamide, showed the adamantyl moiety of the inhibitor residing in a less utilized binding pocket than that of most hydrophobic inhibitors, lined by the amino acid residues Ile91, Val121 and Phe131. This binding site may explain the diverse inhibition profiles of 5-carboxamide- and sufonamide-derivatized 1,3,4-thiadiazole-2-sulfonamides and offers a hot spot for designing isoform selective inhibitors, considering that residues 91 and 131 are highly variable among the 13 catalytically active isoforms.

Carbonic anhydrase activators. The first activation study of a coral secretory isoform with amino acids and amines

The activity of the coral Stylophora pystillata secretory carbonic anhydrase STPCA has been tested in presence of amino acids and amines. All the investigated compounds showed a positive, activating effect on k(cat) and have been separated in weak (K(A) in the range of 21-126 microM), medium (10.1-19 microM) and strong enzyme activators (K(A) of 0.18-3.21 microM). D-DOPA was found to be the best coral enzyme activator, with an activation constant K(A) of 0.18 microM. This enhancement of STPCA activity, as well as previous enzyme inhibition results, might now be tested on living organisms to better understand the role played by these enzymes in the coral calcification processes.

Synthesis, characterization, antibacterial activities and carbonic anhydrase enzyme inhibitor effects of new arylsulfonylhydrazone and their Ni(II), Co(II) complexes

Ethane sulfonic acide hydrazide (esh: CH(3)CH(2)SO(2)NHNH(2)) derivatives as 5-methylsalicyl-aldehydeethanesulfonylhydrazone (5msalesh), 5-methyl-2-hydroxyacetophenoneethane sulfonylhydrazone (5mafesh) and their Ni(II), Co(II) complexes have been synthesized for the first time. The structure of these compounds has been investigated by elemental analysis, FT-IR, (1)H NMR, (13)C NMR, LC/MS, UV-vis spectrophotometric method, magnetic susceptibility, thermal studies and conductivity measurements. The antibacterial activities of synthesized compounds were studied against Gram positive bacteria; Staphylococcus aureus, Bacillus subtilis, Bacillus magaterium and Gram negative bacteria; Salmonella enteritidis, Escherichia coli by using the microdilution broth method. The biological activity screening showed that ligands have more activity than complexes against the tested bacteria. The inhibition activities of these compounds on carbonic anhydrase II (CA II) have been investigated by comparing IC(50) and K(i) values and it has been found that 5msalesh and its complexes have more enzyme inhibition efficiency than other compounds.

CP-MLR directed QSAR study of carbonic anhydrase inhibitors: sulfonamide and sulfamate inhibitors

The inhibition activities of sulfonamide and sulfamate derivatives for human carbonic anhydrases have been quantitatively analyzed using DRAGON descriptors. QSAR models have been obtained through combinatorial protocol-multiple linear regression (CP-MLR) computational procedure. For the hCA I inhibition activity, a higher value of information content index of the 1-order neighborhood symmetry (IC1) and a lower value of the Moran autocorrelations, MATS2v and MATS1p, along with a lower number of sulfur atoms in a molecular structure (nRSR) is beneficial to the activity. A higher number of 5-membered rings (nR05), a bigger distance between nitrogen and sulfur T(N..S), and a higher value of van der Waals volume weighted descriptor (GATS6v), are helpful to improve the hCA II inhibition activity. For the inhibition of hpCA, a lower value of the descriptors Jhetv and PW5, and higher values of the eigenvalue sum from Z weighted distance matrix, SEigZ, the Moran autocorrelation of lag 8 weighted by atomic van der Waals volumes, MATS8v and the Moran autocorrelation of lag 4 weighted by atomic Sanderson electronegativities, MATS4e are favorable. The derived significant models in such descriptors may further be used to synthesize new potential compounds and to decipher the mode of their actions at molecular level.

Carbonic anhydrase inhibitors. Inhibition of the beta-class enzyme from the pathogenic yeast Candida glabrata with anions

A beta-carbonic anhydrase (CA, EC 4.2.1.1), the protein encoded by the NCE103 gene of Candida glabrata which also present in Candida albicans and Saccharomycescerevisiae, was cloned, purified, characterized kinetically and investigated for its inhibition by a series simple, inorganic anions such as halogenides, pseudohalogenides, bicarbonate, carbonate, nitrate, nitrite, hydrogen sulfide, bisulfite, perchlorate, sulfate and some isosteric species. The enzyme showed significant CO(2) hydrase activity, with a k(cat) of 3.8 x 10(5)s(-1) and k(cat)/K(M) of 4.8 x 10(7)M(-1)s(-1). The Cà glabrata CA (CgCA) was moderately inhibited by metal poisons (cyanide, azide, cyanate, thiocyanate, K(I)s of 0.60-1.12 mM) but strongly inhibited by bicarbonate, nitrate, nitrite and phenylarsonic acid (K(I)s of 86-98 microM). The other anions investigated showed inhibition constants in the low millimolar range, with the exception of bromide and iodide (K(I)s of 27-42 mM).

Carbonic anhydrase activators: activation of the beta-carbonic anhydrase Nce103 from the yeast Saccharomyces cerevisiae with amines and amino acids

The protein encoded by the Nce103 gene of Saccharomyces cerevisiae, a beta-carbonic anhydrase (CA, EC 4.2.1.1) designated as scCA, was investigated for its activation with amines and amino acids. scCA was poorly activated by amino acids such as l-/d-His, Phe, DOPA, Trp (K(A)s of 82-90 microM) and more effectively activated by amines such as histamine, dopamine, serotonin, pyridyl-alkylamines, aminoethyl-piperazine/morpholine (K(A)s of 10.2-21.3 microM). The best activator was l-adrenaline, with an activation constant of 0.95 microM. This study may help to better understand the catalytic/activation mechanisms of the beta-CAs and eventually to design modulators of CA activity for similar enzymes present in pathogenic fungi, such as Candida albicans and Cryptococcus neoformans.