Synthesis of 2‐amino‐3‐cyanopyridine derivatives and investigation of their carbonic anhydrase inhibition effects

The conversion of carbon dioxide (CO₂) and bicarbonate (HCO₃⁻) to each other is very important for living metabolism. Carbonic anhydrase (CA, E.C.4.2.1.1), a metalloenzyme familly, catalyzes the interconversion of these ions (CO₂ and HCO₃⁻) and are very common in living organisms. In this study, a series of novel 2‐amino‐3‐cyanopyridines supported with some functional groups was synthesized and tested as potential inhibition effects against both cytosolic human CA I and II isoenzymes (hCA I and II) using by Sepharose‐4B‐l ‐tyrosine‐sulfanilamide affinity chromatography. The structural elucidations of novel 2‐amino‐3‐cyanopyridines were achieved by NMR, IR, and elemental analyses. K _i values of the novel synthesized compounds were found in range of 2.84–112.44 μM against hCA I and 2.56–31.17 μM against hCA II isoenzyme. While compound 7d showed the best inhibition activity against hCA I (K _i: 2.84 μM), the compound 7b demonstrated the best inhibition profile against hCA II isoenzyme (K _i: 2.56 μM).     

Synthesis and carbonic anhydrase inhibitory properties of amino acid – coumarin/quinolinone conjugates incorporating glycine,alanine and phenylalanine moieties

N-Protected amino acids (Gly, Ala and Phe) were reacted with amino substituted coumarin and quinolinone derivatives, leading to the corresponding N-protected amino acid–coumarin/quinolinone conjugates. The carbonic anhydrase (CA, EC 4.2.1.1) inhibitory activity of the new compounds was assessed against various human (h) isoforms, such as hCA I, hCA II, hCA IV and hCA XII. The quinolinone conjugates were inactive as enzyme inhibitors, whereas the coumarins were ineffective hCA I/II inhibitors (K_Is?>?50?μM) but were submicromolar hCA IV and XII inhibitors, with inhibition constants ranging between 92?nM and 1.19?μM for hCA IV, and between 0.11 and 0.79?μM for hCA XII. These coumarin derivatives, as many others reported earlier, thus show an interesting selective inhibitory profile for the membrane-bound over the cytosolic CA isoforms.     

Synthesis of 3,4-dihydroxypyrrolidine-2,5-dione and 3,5-dihydroxybenzoic acid derivatives and evaluation of the carbonic anhydrase I and II inhibition

Abstract

The inhibition of two human cytosolic carbonic anhydrase (hCA, EC 4.2.1.1) isozymes I and II, with some 3,4-dihydroxypyrrolidine-2,5-dione and 3,5-dihydroxybenzoic acid derivatives, were investigated by using the esterase assay, with 4-nitrophenyl acetate (4-NPA) as substrate. Compounds 10–13 showed K_I values in the range of 112.7–441.5?μM for hCA I and of 3.5–10.76?μM against hCA II, respectively. These hydroxyl group containing compounds generally were competitive inhibitors. Some hydroxyl group containing compounds investigated here showed effective hCA II inhibitory effects, in the same range as the clinically used sulfonamide acetazolamide, and might be used as leads for generating enzyme inhibitors possibly targeting other CA isoforms which have not been yet assayed for their interactions with such agents.     

Investigation of piperazines as human carbonic anhydrase I,II, IV and VII activators

Four human (h) carbonic anhydrase isoforms (CA, EC 4.2.1.1), hCA I, II, IV, and VII, were investigated for their activation profile with piperazines belonging to various classes, such as N-aryl-, N-alkyl-, N-acyl-piperazines as well as 2,4-disubstituted derivatives. As the activation mechanism involves participation of the activator in the proton shuttling between the zinc-coordinated water molecule and the external milieu, these derivatives possessing diverse basicity and different scaffolds were appropriate for being investigated as CA activators (CAAs). Most of these derivatives showed CA activating properties against hCA I, II, and VII (cytosolic isoforms) but were devoid of activity against the membrane-associated hCA IV. For hCA I, the K_As were in the range of 32.6–131?µM; for hCA II of 16.2–116?µM, and for hCA VII of 17.1–131?µM. The structure-activity relationship was intricate and not easy to rationalize, but the most effective activators were 1-(2-piperidinyl)-piperazine (K_A of 16.2?µM for hCA II), 2-benzyl-piperazine (K_A of 17.1?µM for hCA VII), and 1-(3-benzylpiperazin-1-yl)propan-1-one (K_A of 32.6?µM for hCA I). As CAAs may have interesting pharmacologic applications in cognition and for artificial tissue engineering, investigation of new classes of activators may be crucial for this relatively new research field.     

Spirobisnaphthalenes effectively inhibit carbonic anhydrase

This study explores the correlation between human carbonic anhydrase (CA, EC 4.2.1.1) isoforms I and II (hCA I, II) and the inhibitory features of some spirobisnaphthalene derivatives. A group of spirobisnaphthalenes was synthesized and their hCA I and II inhibitory effects was investigated. The K_i values were similar for both CA isoenzymes, the compounds showing good inhibitory activity. K_i values ranged between 1.60 and 460.42?µM for hCA I and between 0.39 and 419.42?µM for hCA II, respectively. The spirobisnaphthalenes derivatives might be useful for designing CA inhibitors belonging to novel chemotypes compared to the highly investigated sulfonamides, sulfamates or coumarins.     

Inhibition of mammalian carbonic anhydrase isoforms I,II and VI with thiamine and thiamine-like molecules

Here we determined the in vitro inhibitory effects of 5-(2-hydroxyethyl)-3,4-dimethylthiazolium iodide (1), 3-Benzyl-5-(2-hydroxyethyl)-4-methylthiazolium chloride (2) and thiamine (3) on human erythrocyte carbonic anhydrase I, II isozymes (hCA I and hCA II) and secreted isoenzyme CA VI. K_I values ranged from 0.38 to 2.27 µM for hCA I, 0.085 to 0.784 µM for hCA II and 0.062 to 0.593 µM for hCA VI, respectively. The compounds displayed relatively strong actions on hCA II, in the same range as the clinically used sulfonamidesethoxzolamide, zonisamide and acetazolamide.     

Synthesis and carbonic anhydrase inhibitory properties of novel coumarin derivatives

A newly series of water-soluble 1-alkyl-3-(4-methyl-7, 8-dihydroxy-2H-chromen-2-one) benzimidazolium chloride salts (3a-j) were synthesized and their inhibitory effects on the activity of purified human carbonic anhydrase (hCA) I and II were evaluated. hCA I and II from human erythrocytes were purified by a simple one step procedure by using Sepharose 4B-L-tyrosine-sulphanilamide affinity column. The result showed that all the synthesized compounds were inhibited the CA isoenzymes activity. Among them, 3g and 3j were found to be most active (IC₅₀ = 22.09 µM and 20.33 µM) for hCA I and hCA II, respectively.     

Synthesis and evaluation of sulfonamide-bearing thiazole as carbonic anhydrase isoforms hCA I and hCA II

Sulfonamide-bearing thiazole compounds were synthesized and their inhibitory effects on the activity of purified human carbonic anhydrase I and II were evaluated. Human carbonic anhydrase isoenzymes (hCA-I and hCA-II) were purified from erythrocyte cells by affinity chromatography. The inhibitory effects of the 12 synthesized sulfonamide (5a–l) on the hydratase and esterase activities of these isoenzymes (hCA-I and hCA-II) were studied in vitro. In relation to these activities, the inhibition equilibrium constants (Ki) were determined. The results showed that all the synthesized compounds inhibited the CA isoenzyme activity. Among them 5b was found to be the most active (IC_50?=_?0.35?μM; Ki: 0.33?μM) for hCA I and hCA II.     

Carbonic anhydrase I,II, IV and IX inhibition with a series of 7-amino-3,4-dihydroquinolin-2(1H)-one derivatives

A series of new derivatives was prepared by derivatisation of the 7-amino moiety present in 7-amino-3,4-dihydroquinolin-2(1H)-one, a compound investigated earlier as CAI. The derivatisation was achieved by: i) reaction with arylsulfonyl isocyanates/aryl isocyanates; (ii) reaction with fluorescein isothiocyanate; (iii) condensation with substituted benzoic acids in the presence of carbodiimides; (iv) reaction with 2,4,6-trimethyl-pyrylium tetrafluoroborate; (v) reaction with methylsulfonyl chloride and (vi) reaction with maleic anhydride. The new compounds were assayed as inhibitors of four carbonic anhydrases (CA, EC 4.2.1.1) human (h) isoforms of pharmacologic relevance, the cytosolic hCA I and II, the membrane-anchored hCA IV and the transmembrane, tumour-associated hCA IX. hCA IX was the most inhibited isoform (K_Is ranging between 243.6 and 2785.6?nm) whereas hCA IV was not inhibited by these compounds. Most derivatives were weak hCA I and II inhibitors, with few of them showing K_Is?相似文献   

In vitro and in vivo effects of some benzodiazepine drugs on human and rabbit erythrocyte carbonic anhydrase enzymes

Carbonic anhydrase inhibitors (CAIs) are a class of pharmaceuticals used as antiglaucoma agents, diuretics and antiepileptics. Thus, discovery of novel CAIs has become of great importance in the recent years. In the current study, in vitro and in vivo inhibition effects of benzodiazepine drugs, diazepam and midazolam, on human erythrocytes carbonic anhydrase I and II isozymes were investigated. After purification of the isoenzymes, in vitro inhibition assays were performed and K_i values were determined to be of 141.5 μM and 40.7 μM for hCA I and of 5.11 μM and 0.58 μM against hCA II by the esterase activity assay, respectively. The drugs showed strong inhibitory effects on hCA II, in the same range as the clinically used sulphonamide acetazolamide. For in vivo studies, five adult male New Zealand White rabbits (3–4.2?kg) were selected for intravenous administrations of the drugs (2?mg/kg and 0.2?mg/kg body weight, respectively). The enzyme was significantly inhibited by 2?mg/kg diazepam (p?<?0.05), and 0.2?mg/kg midazolam (p?<?0.05) for up to 30?min following intravenous administration.     

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).     

The determination of the carbonic anhydrases activators in vitro effect of mixed donor crown ethers

Carbonic anhydrases (CAs) play an important function in various physiological and pathological processes. Therefore, many researchers work in this field in order to design and synthesize new drugs. Both inhibitors and activators of CAs, which are associated with the diagnosis and treatment of many diseases, are very important. The emergence of the use of CA activators in the treatment of Alzheimer has led many scholars to work on this issue. In this study, CA activators and inhibitors are determined. The crown ethers compounds ( 1 , 2 , 3 , 6 , 7 , 8 , and 9 ) were found to cause activation on enzyme activities of hCA I and II. The AC₅₀ values on hCA I and II of the compounds are in the range of 4.6565–374.979 μM. The 4 (IC₅₀; 1.301 and 3.215 μM for hCA I and II) and 5 (IC₅₀; 73.96 and 378.5 μM for hCA I and II) compounds were found to cause inhibition on enzyme activities of hCA I and II.     

Carbonic anhydrase inhibitors. Inhibition of the human cytosolic isoforms I and II and transmembrane,tumor-associated isoforms IX and XII with boronic acids

A series of aromatic, arylalkenyl- and arylalkyl boronic acids were assayed as inhibitors of four physiologically relevant carbonic anhydrase (CA, EC 4.2.1.1) isoforms, the cytosolic human (h) hCA I and II, and the transmembrane, tumor-associated hCA IX and XII. The best hCA I and II inhibitor was biphenyl boronic acid with, a K_I of 3.7–4.5 μM, whereas the remaining derivatives showed inhibition constants in the range of 6.0–1560 μM for hCA I and of 6.0–1050 μM for hCA II, respectively. hCA IX and XII were effectively inhibited by most of the aromatic boronic acids (K_Is of 7.6–12.3 μM) whereas the arylalkenyl and aryl–alkyl derivatives generally showed weaker inhibitory properties (K_Is of 34–531 μM). The nature of the moiety substituting the boronic acid group strongly influenced the CA inhibitory activity, with inhibitors possessing low micromolar to millimolar activity being detected in this small series of investigated compounds. This study proves that the B(OH)₂ moiety represents a new zinc-binding group for the generation of effective CA inhibitors targeting isoforms with medicinal chemistry applications. The boronic acids probably bind to the Zn(II) ion within the CA active site leading to a tetrahedral geometry of the metal ion and of the B(III) derivative.     

(3,4-Dihydroxyphenyl)(2,3,4-trihydroxyphenyl)methanone and its derivatives as carbonic anhydrase isoenzymes inhibitors

In this study, we have synthesised (3,4-dihydroxyphenyl)(2,3,4-trihydroxyphenyl)methanone and a series of its derivatives (5, 13–16) and tested the ability of these compounds to inhibit two metalloenzyme human carbonic anhydrase (hCA, EC 4.2.1.1) isozymes, hCA I and hCA II. The synthesised compounds showed inhibitory effect on hCA I and hCA II isozymes. The results showed that synthesised compounds (5, 13–16) demonstrated the best inhibition activity against hCA I (IC₅₀: 3.22–54.28 μM) and hCA II (IC₅₀: 18.52–142.01 μM). The compound 14 showed the highest inhibiton effect against hCA I (IC₅₀: 3.22 μM; K_i: 1.19?±?1.4 μM). On the other hand, the compound 13 showed the highest inhibiton effect against hCA II (IC₅₀: 18.52 μM; K_i: 3.25?±?1.13 μM).     

α-Carbonic anhydrases are sulfatases with cyclic diol monosulfate esters

Carbonic anhydrases (CA) catalyze activated ester hydrolysis in addition to the hydration of CO₂ to bicarbonate. They also show phosphatase activity with 4-nitrophenyl phosphate as substrate but not sulfatase with the corresponding sulfate. Here we prove that the enzyme is catalyzing the synthesis of cyclic diols from sulfate esters. 5-, 6- and 8-membered ring cyclic sulfates incorporating a neighboring secondary alcohol moiety were treated with CA II and yielded the corresponding cyclic diols. Inhibitory properties of obtained cyclic and original sulfate esters were then investigated on human carbonic anhydrase I (hCA I), hCA II, hCA IV and hCA VI (h?=?human isoform). K_I-s of these compounds ranged between 32.7–423 μM against hCA I, 2.13–32.4 μM against hCA II, 13.7–234 μM against hCA IV and 76–278 μM against CA VI, respectively. The sulfatase activity of CA with such esters is amazing considering the fact that 4-nitrophenyl-sulfate is not a substrate of these enzymes.     

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 impact of hydroquinone on acetylcholine esterase and certain human carbonic anhydrase isoenzymes (hCA I,II, IX,and XII)

Abstract

Carbonic anhydrases (CAs) are widespread and the most studied members of a great family of metalloenzymes in higher vertebrates including humans. CAs were investigated for their inhibition of all of the catalytically active mammalian isozymes of the Zn²⁺-containing CA, (CA, EC 4.2.1.1). On the other hand, acetylcholinesterase (AChE. EC 3.1.1.7), a serine protease, is responsible for ACh hydrolysis and plays a fundamental role in impulse transmission by terminating the action of the neurotransmitter ACh at the cholinergic synapses and neuromuscular junction. In the present study, the inhibition effect of the hydroquinone (benzene-1,4-diol) on AChE activity was evaluated and effectively inhibited AChE with K_i of 1.22?nM. Also, hydroquinone strongly inhibited some human cytosolic CA isoenzymes (hCA I and II) and tumour-associated transmembrane isoforms (hCA IX, and XII), with K_is in the range between micromolar (415.81?μM) and nanomolar (706.79?nM). The best inhibition was observed in cytosolic CA II.     

Inhibition properties of some flavonoids on carbonic anhydrase I and II isoenzymes purified from human erythrocytes

Carbonic anhydrases (CAs, E.C.4.2.1.1) play a critical role in many important physiological events and treatment of some diseases. Flavonoids or phenolic compounds have been discovered as novel CAs inhibitors instead of the traditional sulfonamides, with different binding to CAs, pro‐drug activities, and new inhibition mechanisms. Here, we investigated the inhibition effects of some flavonoids including malvin, callistephin, oenin, pelargonin, silychristin, and 1‐(4‐methoxyphenyl)‐2‐methyl‐3‐nitro‐1‐H‐indol‐6‐ol (ID‐8) against hCA I and II, which purified from human erythrocytes by affinity column chromatography. Both hCA isoenzymes were inhibited by flavonoids, with IC₅₀ and K_i values in the range of 2.34 nM to 346.5 μM and 51.01–99.55 μM for hCA I and 86.60–750.00 μM for hCA II, respectively. These results showed that flavonoids especially malvin and oenin effectively inhibited hCA I and II isoenzymes. Hence, they may be used as an effective CA inhibitor in medical applications for treatment of certain diseases such as glaucoma, in the future.     

In vitro effects of some anabolic compounds on erythrocyte carbonic anhydrase I and II

The in vitro effects of the anabolic compounds, zeranol, 17 β-estradiol, diethylstilbestrol (DES), and trenbolone, on the activity of purified human carbonic anhydrase I and II were evaluated. In vitro CA enzyme activity was determined colorimetrically using the CO₂ hydration method of Maren. IC₅₀ values of the compounds that caused inhibition were determined by means of activity percentage diagrams. The IC₅₀ concentrations of zeranol, 17 β-estradiol, DES and trenbolone on hCA I were 94, 55, 10, 898 µM and for hCA II 89, 159, 439 and 101 μM, respectively.     

The synthesis of novel pyrazole-3,4-dicarboxamides bearing 5-amino-1,3,4-thiadiazole-2-sulfonamide moiety with effective inhibitory activity against the isoforms of human cytosolic carbonic anhydrase I and II

A series of 1-(3-substituted-phenyl)-5-phenyl-N³,N⁴-bis(5-sulfamoyl-1,3,4-thiadiazol-2-yl)-1H-pyrazole-3,4-dicarboxamides (4–15) were synthesized. The structures of these pyrazole-sulfonamides were confirmed by FT-IR, ¹H NMR, ¹³C NMR and elemental analysis methods. Human cytosolic carbonic anhydrase (CA, EC 4.2.1.1) isozymes (hCA I and II) were purified from erythrocyte cells by affinity chromatography. The inhibitory effects of newly synthesized derivatives (4–15) were investigated in vitro on esterase activities of these isozymes. The K_i values were determined as 0.119–3.999 μM for hCA I and 0.084–0.878 μM for hCA II. The results showed that the compound 6 for hCA I and the compound 11 for hCA II had the highest inhibitory effect. Beside that, the compound 8 had the lowest inhibition effect on both isozymes.