The human carbonic anhydrase isoenzymes I and II inhibitory effects of some hydroperoxides,alcohols, and acetates

The carbonic anhydrases (CAs, EC 4.2.1.1) represent a superfamily of widespread enzymes, which catalyze a crucial biochemical reaction, the reversible hydration of carbon dioxide to bicarbonate and protons. Human CA isoenzymes I and II (hCA I and hCA II) are ubiquitous cytosolic isoforms. In this study, a series of hydroperoxides, alcohols, and acetates were tested for the inhibition of the cytosolic hCA I and II isoenzymes. These compounds inhibited both hCA isozymes in the low nanomolar ranges. These compounds were good hCA I inhibitors (K_is in the range of 24.93–97.99?nM) and hCA II inhibitors (K_is in the range of 26.04–68.56?nM) compared to acetazolamide as CA inhibitor (K_i: 34.50?nM for hCA I and K_i: 28.93?nM for hCA II).     

Synthesis and inhibitory properties of some carbamates on carbonic anhydrase and acetylcholine esterase

A series of carbamate derivatives were synthesized and their carbonic anhydrase I and II isoenzymes and acetylcholinesterase enzyme (AChE) inhibitory effects were investigated. All carbamates were synthesized from the corresponding carboxylic acids via the Curtius reactions of the acids with diphenyl phosphoryl azide followed by addition of benzyl alcohol. The carbamates were determined to be very good inhibitors against for AChE and hCA I, and II isoenzymes. AChE inhibition was determined in the range 0.209–0.291?nM. On the other hand, tacrine, which is used in the treatment of Alzheimer’s disease possessed lower inhibition effect (K_i: 0.398?nM). Also, hCA I and II isoenzymes were effectively inhibited by the carbamates, with inhibition constants (K_i) in the range of 4.49–5.61?nM for hCA I, and 4.94–7.66?nM for hCA II, respectively. Acetazolamide, which was clinically used carbonic anhydrase (CA) inhibitor demonstrated K_i values of 281.33?nM for hCA I and 9.07?nM for hCA II. The results clearly showed that AChE and both CA isoenzymes were effectively inhibited by carbamates at the low nanomolar levels.     

The human carbonic anhydrase isoenzymes I and II (hCA I and II) inhibition effects of trimethoxyindane derivatives

Carbonic anhydrases (CAs, EC 4.2.1.1) had six genetically distinct families described to date in various organisms. There are 16 known CA isoforms in humans. Human CA isoenzymes I and II (hCA I and hCA II) are ubiquitous cytosolic isoforms. Acetylcholine esterase (AChE. EC 3.1.1.7) is a hydrolase that hydrolyzes the neurotransmitter acetylcholine relaying the signal from the nerve. In this study, some trimethoxyindane derivatives were investigated as inhibitors against the cytosolic hCA I and II isoenzymes, and AChE enzyme. Both hCA isozymes were inhibited by trimethoxyindane derivatives in the low nanomolar range. These compounds were good hCA I inhibitors (Kis in the range of 1.66–4.14?nM) and hCA II inhibitors (Kis of 1.37–3.12?nM) and perfect AChE inhibitors (Kis in the range of 1.87–7.53?nM) compared to acetazolamide as CA inhibitor (Ki: 6.76?nM for hCA I and Ki: 5.85?nM for hCA II) and Tacrine as AChE inhibitor (Ki: 7.64?nM).     

7-Amino-3,4-dihydro-1H-quinolin-2-one,a compound similar to the substituted coumarins,inhibits α-carbonic anhydrases without hydrolysis of the lactam ring

Abstract

7-Amino-3,4-dihydro-1H-quinolin-2-one, a compound structurally similar to coumarins, recently discovered class of inhibitors of the α-carbonic anhydrases (CAs, EC 4.2.1.1) was investigated for its interaction with all human (h) CA isoforms, hCA I-XIV. The compound was not an inhibitor of the cytosolic, widespread isoform hCA II (K_I?>?10?µM), was a weak inhibitor of hCA I, III, IV, VA, VI and XIII (K_Is in the range of 0.90–9.5?µM) but effectively inhibited the cytosolic isoform hCA VII (K_I of 480?nM) as well as the transmembrane isoforms hCA IX, XII and XIV (K_Is in the range of 16.1–510?nM). Against many CA isoforms this lactam was a better inhibitor compared to the structurally similar 4-methyl-7-aminocoumarin, but unlike this compound, the lactam ring was not hydrolyzed and the inhibition was due to the intact bicyclic amino-quinolinone scaffold. Bicyclic lactams strucurally related to coumarins are thus a new class of CA inhibitors possessing however a distinct inhibition mechanism compared to the coumarins which undergo a hydrolysis of their lactone ring for generating the enzyme inhibitory species.     

Discovery of novel 1,3-diaryltriazene sulfonamides as carbonic anhydrase I,II, VII,and IX inhibitors

A series of new 1,3-diaryltriazene sulfonamides was synthesised by reaction of diazonium salt of metanilamide (3-aminobenzene sulfonamide) with substituted aromatic amines. The obtained new compounds were assayed as inhibitors of four physiologically and pharmacologically relevant human (h) isoforms of carbonic anhydrases (CA, EC 4.2.1.1), specifically, hCA I, hCA II, and hCA VII (cytosolic isoforms), as well as the tumour-associated membrane-bound isoform hCA IX. All isoforms investigated here were inhibited by the newly synthesised 1,3-diaryltriazene sulfonamide derivatives from the micromolar to the nanomolar range. The cytosolic isoforms were inhibited with K_is in the range of 92.3–8371.1?nM (hCA I), 4.3–9194.0?nM (hCA II), and 15.6–9477.8?nM (hCA VII), respectively. For the membrane-bound tumour-associated isoform hCA IX, the K_I-s ranged between 50.8 and 9268.5?nM. The structure–activity relationship (SAR) with these newly synthesised metanilamide derivatives are discussed in detail.     

Novel N‐propylphthalimide‐ and 4‐vinylbenzyl‐substituted benzimidazole salts: Synthesis,characterization, and determination of their metal chelating effects and inhibition profiles against acetylcholinesterase and carbonic anhydrase enzymes

The novel N‐propylphthalimide‐substituted and 4‐vinylbenzyl‐substituted N‐heterocyclic carbene (NHC) precursors were synthesized by N‐substituted benzimidazolium with aryl halides. The novel N‐propylphthalimide‐substituted and 4‐vinylbenzyl‐substituted NHC precursors have been characterized by using ¹H NMR, ¹³C NMR, FTIR spectroscopy, and elemental analysis techniques. They were tested for the inhibition of AChE and hCA enzymes and demonstrated efficient inhibition profiles with K_i values in the range of 351.0–1269.9 nM against hCA I, 346.6–1193.1 nM against hCA II, and 19.0–76.3 nM against AChE. On the other hand, acetazolamide, a clinically used molecule, utilized as CA inhibitor, obtained a K_i value of 1246.7 nM against hCA I and 1407.6 nM against hCA II. Additionally, tacrine inhibited AChE and obtained a K_i value of 174.6 nM.     

Dipotassium-trioxohydroxytetrafluorotriborate,K2[B3O3F4OH], is a potent inhibitor of human carbonic anhydrases

Abstract

The boron heterocyclic compound dipotassium-trioxohydroxytetrafluorotriborate (K₂[B₃O₃F₄OH]) was investigated as inhibitor of the zinc enzyme, carbonic anhydrase (CA, EC 4.2.1.1). Eleven human (h) CA isoforms, hCA I–IV, VA, VI, VII, IX and XII–XIV, were included in the investigations. The anion, similar to tetraborate or phenylboronic acid, inhibited most of them. hCA III was not inhibited by K₂[B₃O₃F₄OH], whereas hCA VA, hCA VI, hCA IX and hCA XIII were inhibited in the submillimolar range, with K_Is of 0.31–0.63?mM. hCA I and II (cytosolic, widespread isoforms), hCA IV (membrane-bound isoform), hCA XII (tumor-associated, transmembrane) and hCA XIV (transmembrane) were much more effectively inhibited by this anion, with inhibition constants ranging from 25 to 93?µM. hCA VII, a cytosolic enzyme present in the brain and associated to oxidative stress, was very effectively inhibited by K₂[B₃O₃F₄OH], with a K_I of 8.0?µM. We propose that K₂[B₃O₃F₄OH] binds to the metal ion from the enzyme active site, coordinating to the Zn(II) ion monodentately through its B-OH functionality. We hypothesize that some of the beneficial antitumor effects reported for K₂[B₃O₃F₄OH] may be due to the inhibition of CAs present in skin tumors.     

Carbonic anhydrase inhibitors: Synthesis and inhibition of the human carbonic anhydrase isoforms I,II, IX and XII with benzene sulfonamides incorporating 4- and 3-nitrophthalimide moieties

A series of 4 and 5 nitro-1,3-dioxoisoindolin-2-yl benzenesulfonamide derivatives (compounds 1–8) was synthesized by reaction of benzenesulfonamide derivatives with 4 and 3-nitrophthalic anhydrides. These new sulfonamides were investigated as inhibitors of the zinc metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1) and more specifically against the human (h) cytosolic isoforms hCA I and II and the transmembrane, tumor-associated hCA IX and XII. Most of the novel compounds were medium potency-weak hCA I inhibitors (K_is in the range of 295–10,000 nM), but were more effective hCA II inhibitors (K_is of 1.7–887 nM). The tumor-associated hCA IX was also inhibited, with K_is in the micromolar range, whereas against hCA XII the inhibition constants were in the range of 90–3746 nM. The structure–activity relationship (SAR) with this series of sulfonamides is straightforward, with the main features leading to good activity for each isoforms being established. The high sequence hCA alignment homology and molecular docking studies was performed in order to rationalize the activities reported and binding mode to different hCA as inhibitors.     

The effect of caffeic acid phenethyl ester (CAPE) on metabolic enzymes including acetylcholinesterase,butyrylcholinesterase, glutathione S-transferase,lactoperoxidase, and carbonic anhydrase isoenzymes I,II, IX,and XII

Caffeic acid phenethyl ester (CAPE) is an active component of honeybee propolis extracts. Carbonic anhydrases (CAs, EC 4.2.1.1) are widespread and intensively studied metalloenzymes present in higher vertebrates including humans as many diverse isoforms. Acetylcholinesterase (AChE) is responsible for acetyl choline (ACh) hydrolysis and plays a fundamental role in nerve impulse transmission by terminating the action of the ACh neurotransmitter at cholinergic synapses and neuromuscular junctions. Butyrylcholinesterase (BChE) is another enzyme abundantly present in the liver and released into blood in a soluble form. Lactoperoxidase (LPO) is an enzyme involved in fighting pathogenic microorganisms whereas glutathione S-transferases (GSTs) are dimeric proteins present both in prokaryotic and eukaryotic organisms and involved in cellular detoxification mechanisms. In the present study, the inhibition effect of CAPE on human carbonic anhydrase (hCA) isoforms I, II, IX, and XII, AChE, BChE, LPO, and GST was evaluated. CAPE inhibited these enzymes with K_is in the range between micromolar to picomolar. The best inhibitory effect was observed against AChE and BChE.     

Discovery of curcumin inspired sulfonamide derivatives as a new class of carbonic anhydrase isoforms I,II, IX,and XII inhibitors

A series of curcumin inspired sulfonamide derivatives was prepared from various chalcones and 4-sulfamoyl benzaldehyde via Claisen–Schmidt condensation. All new compounds were assayed as inhibitors of four human isoforms of the metalloenzyme carbonic anhydrase (hCA, EC 4.2.1.1) isoforms hCA I, II, IX and XII. Interesting inhibitory activities were observed against all these isoforms. hCA I, an isoform involved in several eye diseases was inhibited moderately with K_Is in the range of 191.8–904.2?nM, hCA II, an antiglaucoma drug target was highly inhibited by the new sulfonamides, with K_Is in the range of 0.75–8.8?nM. hCA IX, a tumor-associated isoform involved in cancer progression and metastatic spread was potently inhibited by the new sulfonamides, with K_Is in the range of 2.3–87.3?nM, whereas hCA XII, and antiglaucoma and anticancer drug target, was inhibited with K_Is in the range of 6.1–71.8?nM. It is noteworthy that one of the new compounds, 5d, was found to be almost 9 times more selective against hCA II (K_I =?0.89?nM) over hCA IX and hCA XII, whereas 5e was 3 and 70 times more selective against hCA II (K_I =?0.75?nM) over hCA IX and hCA XII, respectively.     

Synthesis of N-alkyl (aril)-tetra pyrimidine thiones and investigation of their human carbonic anhydrase I and II inhibitory effects

Tetrahydropyrimidine thiones, which are cyclic thiocarbamides derivatives, were synthesised from thiourea, β-diketones and substituted benzaldehydes. A tautomeric form of these derivatives incorporates the thiol functionality, which is known to interact with metal ions from metalloenzymes active sites, such as the carbonic anhydrases (CAs, EC 4.2.1.1) among others. This is a superfamily of widespread enzymes, which catalyses a crucial biochemical reaction, the reversible hydration of carbon dioxide to bicarbonate and protons (H⁺). The newly synthesised N-alkyl (aril)-tetrahydropyrimidine thiones were tested for inhibition of the cytosolic human isoforms I and II (hCA I and II). Both isoforms were effectively inhibited by the newly synthesised thiones. K_i values were in the range of 218.5?±?23.9–261.0?±?41.5?pM for hCA I, and of 181.8?±?41.9–273.6?±?41.4?pM for hCA II, respectively. This under-investigated class of derivatives may bring interesting insights in the field of non-sulphonamide CA inhibitors.     

Novel sulfonamide incorporating piperazine,aminoalcohol and 1,3,5-triazine structural motifs with carbonic anhydrase I,II and IX inhibitory action

A new series of s-triazine derivatives incorporating sulfanilamide, homosulfanilamide, 4-aminoethyl-benzenesulfonamide and piperazine or aminoalcohol structural motifs is reported. Molecular docking was exploited to select compounds from virtual combinatorial library for synthesis and subsequent biological evaluation. The compounds were prepared by using step by step nucleophilic substitution of chlorine atoms from cyanuric chloride (2,4,6-trichloro-1,3,5-triazine). The compounds were tested as inhibitors of physiologically relevant carbonic anhydrase (CA, EC 4.2.1.1) isoforms. Specifically, against the cytosolic hCA I, II and tumor-associated hCA IX. These compounds show appreciable inhibition. hCA I was inhibited with K_Is in the range of 8.5–2679.1 nM, hCA II with K_Is in the range of 4.8–380.5 nM and hCA IX with K_Is in the range of 0.4–307.7 nM. As other similar derivatives, some of the compounds showed good or excellent selectivity ratios for inhibiting hCA IX over hCA II, of 3.5–18.5. 4-[({4-Chloro-6-[(4-hydroxyphenyl)amino]-1,3,5-triazin-2-yl}amino)methyl] benzene sulfonamide demonstrated subnanomolar affinity for hCA IX (0.4 nM) and selectivity (18.50) over the cytosolic isoforms. This series of compounds may be of interest for the development of new, unconventional anticancer drugs targeting hypoxia-induced CA isoforms such as CA IX.     

Synthesis,biological evaluation and in silico studies of novel N-substituted phthalazine sulfonamide compounds as potent carbonic anhydrase and acetylcholinesterase inhibitors

The synthesis, characterization and biological evaluation of a series of novel N-substituted phthalazine sulfonamide (5a-l) are disclosed. Phthalazines which are nitrogen-containing heterocyclic compounds are biologically preferential scaffolds, endowed with versatile pharmacological activity, such as anti-inflammatory, cardiotonic vasorelaxant, anticonvulsant, antihypertensive, antibacterial, anti-cancer action. The compounds were investigated for the inhibition against the cytosolic hCA I, II and AChE. Most screened sulfonamides showed high potency in inhibiting hCA II, widely involved in glaucoma, epilepsy, edema, and other pathologies (K_is in the ranging from 6.32 ± 0.06 to 128.93 ± 23.11 nM). hCA I was inhibited with K_is in the range of 6.80 ± 0.10–85.91 ± 7.57 nM, whereas AChE in the range of 60.79 ± 3.51–249.55 ± 7.89 nM. ADME prediction study of the designed N-substituted phthalazine sulfonamides showed that they are not only with carbonic anhydrase and acetylcholinesterase inhibitory activities but also with appropriate pharmacokinetic, physicochemical parameters and drug-likeness properties. Also, in silico docking studies were investigated the binding modes of selected compounds, to hCA I, II, and AChE.     

A class of carbonic anhydrase IX/XII – selective carboxylate inhibitors

Abstract

A small series of 2,4-dioxothiazolidinyl acetic acids was prepared from thiourea, chloroacetic acid, aromatic aldehydes, and ethyl-2-bromoacetate. They were assayed for the inhibition of four physiologically relevant carbonic anhydrase (CA, EC 4.2.1.1) isoforms of human (h) origin, the cytosolic hCA I and II, and the transmembrane hCA IX and XII, involved among others in tumorigenesis (hCA IX and XII) and glaucoma (hCA II and XII). The two cytosolic isoforms were not inhibited by these carboxylates, which were also rather ineffective as hCA IX inhibitors. On the other hand, they showed submicromolar hCA XII inhibition, with K_Is in the range of 0.30–0.93?µM, making them highly CA XII-selective inhibitors.     

Evaluation of acetylcholinesterase and carbonic anhydrase inhibition profiles of 1,2,3,4,6‐pentasubstituted‐4‐hydroxy‐cyclohexanes

Carbonic anhydrase (CA; EC 4.2.1.1) is used for remedial purposes for several years, as there is significant focus on expanding more new activators (CAAs) and high affinity inhibitors. Alzheimer′s disease and other similar ailments such as dementia and vascular dementia with Lewy bodies reduce cholinergic activity in the important areas involved in cognition and memory. Prevalent drugs for the symptomatic therapy of dementia are significant in increasing the associated cholinergic deficiency by inhibiting acetylcholinesterase (AChE). These six‐membered carbocycles showed nice inhibitory action against AChE and human carbonic anhydrase (hCA) II and I isoforms. The hCA I, II, and AChE were efficiently inhibited by these molecules, with K_i values in the range of 6.70–35.85 nM for hCA I, 18.77–60.84 nM for hCA II, and 0.74–4.60 for AChE, respectively.     

Dithiocarbamates with potent inhibitory activity against the Saccharomyces cerevisiae β-carbonic anhydrase

Dithiocarbamates (DTCs) prepared from primary or secondary amines, which incorporated amino/hydroxyl-alkyl, mono-/bicyclic aliphatic/heterocyclic rings based on the quinuclidine, piperidine, hydroxy-/carboxy-/amino-substituted piperidine, morpholine and piperazine scaffolds, were investigated for the inhibition of α- and β-carbonic anhydrases (CAs, EC 4.2.1.1) of pharmacologic relevance, such as the human (h) isoform hCA I and II, as well as the Saccharomyces cerevisiae β-CA, scCA. The yeast and its β-CA were shown earlier to be useful models of pathogenic fungal infections. The DTCs investigated here were medium potency hCA I inhibitors (K_Is of 66.5–910?nM), were more effective as hCA II inhibitors (K_Is of 8.9–107?nM) and some of them showed excellent, low nanomolar activity against the yeast enzyme, with inhibition constants ranging between 6.4 and 259?nM. The detailed structure activity relationship for inhibition of the yeast and human enzymes is discussed. Several of the investigated DTCs showed excellent selectivity ratios for inhibiting the yeast over the human cytosolic CA isoforms.     

Novel sulphonamides incorporating triazene moieties show powerful carbonic anhydrase I and II inhibitory properties

Abstract

A series of compounds incorporating 3-(3-(2/3/4-substituted phenyl)triaz-1-en-1-yl) benzenesulfonamide moieties were synthesised and their chemical structure was confirmed by physico-chemical methods. Carbonic anhydrase (CA, EC 4.2.1.1) inhibitory effects of the compounds were evaluated against human isoforms hCA I and II. K_I values of these sulphonamides were in the range of 21?±?4–72?±?2?nM towards hCA I and in the range of 16?±?6–40?±?2?nM against hCA II. The 4-fluoro substituted derivative might be considered as an interesting lead due to its effective inhibitory action against both hCA I and hCA II (K_Is of 21?nM), a profile rarely seen among other sulphonamide CA inhibitors, making it of interest in systems where the activity of the two cytosolic isoforms is dysregulated.     

Synthesis and biological evaluation of aminomethyl and alkoxymethyl derivatives as carbonic anhydrase,acetylcholinesterase and butyrylcholinesterase inhibitors

Compounds containing nitrogen and sulfur atoms can be widely used in various fields such as industry, medicine, biotechnology and chemical technology. Therefore, the reactions of aminomethylation and alkoxymethylation of mercaptobenzothiazole, mercaptobenzoxazole and 2-aminothiazole were developed. Additionally, the alkoxymethyl derivatives of mercaptobenzoxazole and 2-aminothiazole were synthesized by a reaction with hemiformals, which are prepared by the reaction of alcohols and formaldehyde. In this study, the inhibitory effects of these molecules were investigated against acetylcholinesterase (AChE), butyrylcholinesterase (BChE) enzymes and carbonic anhydrase I, and II isoenzymes (hCA I and II). Both hCA isoenzymes were significantly inhibited by the recently synthesized molecules, with K_i values in the range of 58–157?nM for hCA I, and 81–215?nM for hCA II. Additionally, the K_i parameters of these molecules for BChE and AChE were calculated in the ranges 23–88 and 18–78?nM, respectively.     

Open saccharin-based secondary sulfonamides as potent and selective inhibitors of cancer-related carbonic anhydrase IX and XII isoforms

A large number of novel secondary sulfonamides based on the open saccharin scaffold were synthesized and evaluated as selective inhibitors of four different isoforms of human carbonic anhydrase (hCA I, II, IX and XII, EC 4.2.1.1). They were obtained by reductive ring opening of the newly synthesized N-alkylated saccharin derivatives and were shown to be inactive against the two cytosolic off-target hCA I and II (K_is?>?10?µM). Interestingly, these compounds inhibited hCA IX in the low nanomolar range with K_is ranging between 20 and 298?nM and were extremely potent inhibitors of hCA XII isoenzyme (K_is ranging between 4.3 and 432?nM). Since hCA IX and XII are the cancer-related isoforms recently validated as drug targets, these results represent an important goal in the development of new anticancer candidates. Finally, a computational approach has been performed to better correlate the biological data to the binding mode of these inhibitors.