Coumarin or benzoxazinone based novel carbonic anhydrase inhibitors: synthesis,molecular docking and anticonvulsant studies

Among many others, coumarin derivatives are known to show human carbonic anhydrase (hCA) inhibitory activity. Since hCA inhibition is one of the underlying mechanisms that account for the activities of some antiepileptic drugs (AEDs), hCA inhibitors are expected to have anti-seizure properties. There are also several studies reporting compounds with an imidazole and/or benzimidazole moiety which exert these pharmacological properties. In this study, we prepared fifteen novel coumarin-bearing imidazolium and benzimidazolium chloride, nine novel benzoxazinone-bearing imidazolium and benzimidazolium chloride derivatives and evaluated their hCA inhibitory activities and along with fourteen previously synthesized derivatives we scanned their anticonvulsant effects. As all compounds inhibited purified hCA isoforms I and II, some of them also proved protective against Maximal electroshock seizure (MES) and ScMet induced seizures in mice. Molecular docking studies with selected coumarin derivatives have revealed that these compounds bind to the active pocket of the enzyme in a similar fashion to that previously described for coumarin derivatives.     

Amide derivatives with pyrazole carboxylic acids of 5-amino-1,3,4-thiadiazole 2-sulfonamide as new carbonic anhydrase inhibitors: Synthesis and investigation of inhibitory effects

Pyrazole carboxylic acid amides of 5-amino-1,3,4-thiadiazole-2-sulfonamide were synthesized from 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carbonyl chloride and 4-benzoyl-1-(3-nitrophenyl)-5-phenyl-1H-pyrazole-3-carbonyl chloride. Carbonic anhydrase isoenzymes (hCA-I and hCA-II) were purified from human erythrocyte cells by the affinity chromatography method. The inhibitory effects of 5-amino-1,3,4-thiadiazole-2-sulfonamide 1, acetazolamide 2 and new synthesized amides on these isozymes have been studied in vitro. The I₅₀ concentrations (the concentration of inhibitor producing a 50% inhibition of CA activity) against hydratase activity ranged from 1.2 to 2.2 nM for hCA-I and from 0.4 to 2 nM for hCA-II. The I₅₀ values against esterase activity ranged from 1.4 to 8 nM for hCA-I and from 1.3 to 6 nM for hCA-II. The K_i values were observed between 8.2·10^{? 5} to 6.2·10^{? 4} M for hCA-I and between 2.9·10^{? 4} to 8.2·10^{? 4} M for hCA-II. The comparison of new synthesized amides to 5-amino-1,3,4-thiadiazole-2-sulfonamide 1, acetazolamide 2 indicated that the new synthesized compounds (18–23) inhibit CA activity more potently than the parent compounds.     

Iodine-mediated one-pot intramolecular decarboxylation domino reaction for accessing functionalised 2-(1,3,4-oxadiazol-2-yl)anilines with carbonic anhydrase inhibitory action

A practical and transition metal-free one-pot domino synthesis of diversified (1,3,4-oxadiazol-2-yl)anilines has been developed employing isatins and hydrazides as the starting materials, in the presence of molecular iodine. The prominent feature of this domino process involves consecutive condensation, hydrolytic ring cleavage, and an intramolecular decarboxylation, in a one-pot process that leads to the oxidative formation of a C–O bond. Fluorescence properties of some of the representative molecules obtained in this way were studied. The synthesised 2-(1,3,4-oxadiazolo-2-yl)aniline-benzene sulphonamides (8a–o) were screened for their carbonic anhydrase (CA, EC 4.2.1.1) inhibitory activity. Most of the compounds exhibited low micromolar to nanomolar activity against human (h) isoforms hCA I, hCA II, hCA IV, and XII, with some compounds displaying selective CA inhibitory activity towards hCA II with K_Is of 6.4–17.6?nM.     

Synthesis of 4-(2-substituted hydrazinyl)benzenesulfonamides and their carbonic anhydrase inhibitory effects

In this study, 4-(2-substituted hydrazinyl)benzenesulfonamides were synthesized by microwave irradiation and their chemical structures were confirmed by ¹H NMR, ¹³CNMR, and HRMS. Ketones used were: Acetophenone (S1), 4-methylacetophenone (S2), 4-chloroacetophenone (S3), 4-fluoroacetophenone (S4), 4-bromoacetophenone (S5), 4-methoxyacetophenone (S6), 4-nitroacetophenone (S7), 2-acetylthiophene (S8), 2-acetylfuran (S9), 1-indanone (S10), 2-indanone (S11). The compounds S9, S10 and S11 were reported for the first time, while S1–S8 was synthesized by different method than literature reported using microwave irradiation method instead of conventional heating in this study. The inhibitory effects of 4-(2-substituted hydrazinyl)benzenesulfonamide derivatives (S1–S11) against hCA I and II were studied. Cytosolic hCA I and II isoenzymes were potently inhibited by new synthesized sulphonamide derivatives with K_is in the range of 1.79?±?0.22–2.73?±?0.08?nM against hCA I and in the range of 1.72?±?0.58–11.64?±?5.21?nM against hCA II, respectively.     

Synthesis of novel sulfonamides under mild conditions with effective inhibitory activity against the carbonic anhydrase isoforms I and II

Novel sulfonamide derivatives 6a–i, as new carbonic anhydrase inhibitors which candidate for glaucoma treatment, were synthesized from the reactions of 4-amino-N-(4-sulfamoylphenyl) benzamide 4 and sulfonyl chloride derivatives 5a–i with high yield (71–90%). The structures of these compounds were confirmed by using spectral analysis (FT-IR, ¹H NMR, ¹³C NMR, LC/MS and HRMS). The inhibition effects of 6a–i on the hydratase and esterase activities of human carbonic anhydrase isoenzymes, hCA I and II, which were purified from human erythrocytes with Sepharose®4B-l-tyrosine-p-aminobenzene sulfonamide affinity chromatography, were studied as in vitro, and IC₅₀ and K_i values were determined. The results show that newly synthesized compounds have quite powerful inhibitory properties.     

Synthesis,characterization and carbonic anhydrase inhibitory activity of novel benzothiazole derivatives

N-protected amino acids were reacted with substituted benzothiazoles to give the corresponding N-protected amino acid-benzothiazole conjugates (60–89%). Their structures were confirmed by proton nuclear magnetic resonance (¹H NMR), carbon-13 nuclear magnetic resonance (¹³C NMR), IR and elemental analysis. Their carbonic anhydrase (CA, EC 4.2.1.1) inhibitory activities were determined against two cytosolic human isoforms (hCA I and hCA II), one membrane-associated (hCA IV) and one transmembrane (hCA XII) enzyme by a stopped-flow CO₂ hydrase assay method. The new compounds showed rather weak, micromolar inhibitory activity against most 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.     

Synthesis,X-ray structure,in silico calculation,and carbonic anhydrase inhibitory properties of benzylimidazole metal complexes

Three coordination compounds of formula {M(bmim)₂Cl₂} were synthetised (M?=?Co, Zn, and Hg) and fully characterised. Each complex incorporates 1-benzyl-2-methylimidazole (bmim) as ligand. The coordination polyhedron around the metal center for all complexes has a quasi-regular tetragonal geometry. Density functional theory calculations were carried out on the title compounds and as well on hypothetical complexes (Cu, Ni), in order to elucidate their electronic and molecular structure. The calculations reproduced the Co, Zn, and Hg experimental structures and could predict stable complexes in the case of Ni(II) and Cu(II) ions. The carbonic anhydrase (CA, EC 4.2.1.1) inhibitory effects of the three complexes were investigated. Only compound {Hg(bmim)₂Cl₂} (3) exhibited a modest inhibitory effect against hCA I, probably due to the affinity of Hg(II) for His residues at the entrance of the active site cavity.     

Design,synthesis and evaluation of N-substituted saccharin derivatives as selective inhibitors of tumor-associated carbonic anhydrase XII

A series of N-alkylated saccharin derivatives were synthesized and tested for the inhibition of four different isoforms of human carbonic anhydrase (CA, EC 4. 2.1.1): the transmembrane tumor-associated CA IX and XII, and the cytosolic CA I and II. Most of the reported derivatives inhibited CA XII in the nanomolar/low micromolar range, hCA IX with K_Is ranging between 11 and 390 nM, whereas they were inactive against both CA I (K_Is >50 μM) and II (K_Is ranging between 39.1 nM and 50 μM). Since CA I and II are off-targets of antitumor carbonic anhydrase inhibitors (CAIs), the obtained results represent an encouraging achievement for the development of new anticancer candidates without the common side effects of non-selective CAIs. Moreover, the lack of an explicit zinc binding function on these inhibitors opens the way towards the exploration of novel mechanisms of inhibition that could explain the high selectivity of these compounds for the inhibition of the transmembrane, tumor-associated isoforms over the cytosolic ones.     

Synthesis,cytotoxicity and carbonic anhydrase inhibitory activities of new pyrazolines

Abstract

A series of polymethoxylated-pyrazoline benzene sulfonamides were synthesized, investigated for their cytotoxic activities on tumor and non-tumor cell lines and inhibitory effects on carbonic anhydrase isoenzymes (hCA I and hCA II). Although tumor selectivity (TS) of the compounds were less than the reference compounds 5-Fluorouracil and Melphalan, trimethoxy derivatives 4, 5, and 6 were more selective than dimethoxy derivatives 2 and 3 as judged by the cytotoxicity assay with the cells both types originated from the gingival tissue. The compound 6 (4-[3-(4-methoxyphenyl)-5-(3,4,5-trimethoxyphenyl)-4,5-dihydro-1H-pyrazol-1-yl] benzene sulfonamide) showed the highest TS values and can be considered as a lead molecule of the series for further investigations. All compounds synthesized showed superior CA inhibitory activity than the reference compound acetazolamide on hCA I, and II isoenzymes, with inhibition constants in the range of 26.5–55.5?nM against hCA I and of 18.9–28.8?nM against hCA II, respectively.     

Inhibition of carbonic anhydrase isoforms I,II, IX and XII with secondary sulfonamides incorporating benzothiazole scaffolds

Carbonic anhydrases (CAs, EC 4.2.1.1) catalyze the fundamental reaction of CO₂ hydration in all living organisms, being actively involved in the regulation of a plethora of patho/physiological conditions. A series of benzothiazole-based sulfonamides were synthesized and tested as possible CA inhibitors. Their inhibitory activity was assessed against the cytosolic human isoforms hCA I and hCA II and the transmembrane hCA IX and hCA XII. Several of the investigated derivatives showed interesting inhibition activity and selectivities for inhibiting hCA IX and hCA XII over the off-target ones hCA I and hCA II. Furthermore, computational procedures were used to investigate the binding mode of this class of compounds, within the active site of hCA IX.     

Sulfonamides incorporating heteropolycyclic scaffolds show potent inhibitory action against carbonic anhydrase isoforms I,II, IX and XII

Three series of polycyclic compounds possessing either primary sulfonamide or carboxylic acid moieties as zinc-binding groups were investigated as inhibitors of four physiologically relevant CA isoforms, the cytosolic hCA I and II, as well as the transmembrane hCA IX and XII. Most of the new sulfonamides reported here showed excellent inhibitory effects against isoforms hCA II, IX and XII, but no highly isoform-selective inhibition profiles. On the other hand, the carboxylates selectively inhibited hCA IX (K_Is ranging between 40.8 and 92.7 nM) without inhibiting significantly the other isoforms. Sulfonamides/carboxylates incorporating polycyclic ring systems such as benzothiopyranopyrimidine, pyridothiopyranopyrimidine or dihydrobenzothiopyrano[4,3-c]pyrazole may be considered as interesting candidates for exploring the design of isoform-selective CAIs with various pharmacologic applications.     

Synthesis,antioxidant and carbonic anhydrase I and II inhibitory activities of novel sulphonamide-substituted coumarylthiazole derivatives

New secondary benzenesulphonamide-substituted coumarylthiazole derivatives were synthesized and their inhibitory effects on purified carbonic anhydrase I and II were evaluated using CO₂ as a substrate. The result showed that all the synthesized compounds exhibited inhibitory activity on both hCA I and hCA II with N-(4-(2-oxo-2H-chromen-3-yl)thiazol-2-yl)naphthalene-2-sulphonamide (5f, IC₅₀ value of 5.63 and 8.48?µM, against hCA I and hCA II, respectively) as the strongest inhibitor revealed from this study. Structure–activity relationship revealed that the inhibitory activity of the synthesized compounds is related to the type of the halogen and bulky substituent on the phenyl ring. In addition, the cupric reducing antioxidant capacities (CUPRAC) and ABTS cation radical scavenging abilities of the synthesized compounds were assayed. 4-methoxy-N-(4-(2-oxo-2H-chromen-3-yl)thiazol-2-yl)benzenesulphonamide (5e) exhibited the strongest ABTS and CUPRAC activity with IC₅₀ value of 48.83?µM and A_0.50 value of 23.29?µM, respectively.     

Amide derivatives with pyrazole carboxylic acids of 5-amino-1,3,4-thiadiazole 2-sulfonamide as new carbonic anhydrase inhibitors: synthesis and investigation of inhibitory effects

Pyrazole carboxylic acid amides of 5-amino-1,3,4-thiadiazole-2-sulfonamide were synthesized from 4-benzoyl-1,5-diphenyl-1H-pyrazole-3-carbonyl chloride and 4-benzoyl-1-(3-nitrophenyl)-5-phenyl-1H-pyrazole-3-carbonyl chloride. Carbonic anhydrase isoenzymes (hCA-I and hCA-II) were purified from human erythrocyte cells by the affinity chromatography method. The inhibitory effects of 5-amino-1,3,4-thiadiazole-2-sulfonamide 1, acetazolamide 2 and new synthesized amides on these isozymes have been studied in vitro. The I(50) concentrations (the concentration of inhibitor producing a 50% inhibition of CA activity) against hydratase activity ranged from 1.2 to 2.2 nM for hCA-I and from 0.4 to 2 nM for hCA-II. The I(50) values against esterase activity ranged from 1.4 to 8 nM for hCA-I and from 1.3 to 6 nM for hCA-II. The K(i) values were observed between 8.2 x 10(- 5) to 6.2 x 10(- 4) M for hCA-I and between 2.9 x 10(- 4) to 8.2 x 10(- 4) M for hCA-II. The comparison of new synthesized amides to 5-amino-1,3,4-thiadiazole-2-sulfonamide 1, acetazolamide 2 indicated that the new synthesized compounds (18-23) inhibit CA activity more potently than the parent compounds.     

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).     

Comparison of the inhibitory potential towards carbonic anhydrase,acetylcholinesterase and butyrylcholinesterase of chalcone and chalcone epoxide

Chalcones and chalcone epoxides are important synthetic intermediates in organic and medicinal chemistry. Chalcones possess a broad spectrum of biological activities; however, 1,3‐diphenyl‐2‐propenone or chalcone has not been given the attention it deserve as its substituted derivatives. In this study, the inhibition effects of chalcone and its epoxidated derivative chalcone epoxide against human carbonic anhydrase isozymes I and II (hCA I and hCA II), acetylcholinesterase (AChE), and butyrylcholinesterase (BuChE) were evaluated. The results obtained showed that both compounds exhibited potent inhibitory activity, with IC₅₀ values less than 10 µM. IC ₅₀ values in the submicromolar (hCA I and hCA II) to low micromolar range (AChE and BuChE) were observed for both compounds. The mechanism of inhibition and the inhibitory constants ( K _i values) for each compound were also determined. Furthermore, chalcone epoxide was docked within the active sites of hCA I, hCA II, AChE, and BuChE to explore its binding mode with the enzymes.     

Microwave-assisted extraction,HPLC analysis,and inhibitory effects on carbonic anhydrase I,II, VA,and VII isoforms of 14 blueberry Italian cultivars

Abstract

The multi-component fingerprint and the biological evaluation of plant-derived material are indispensable for the pharmaceutical field, in food quality control procedures, and in all plant-based products. We investigated the quantitative content of biologically active compounds (anthocyanins and chlorogenic acid) of microwave-assisted blueberry extracts from 14 different Italian cultivars, using validated high-performance liquid chromatography-photodiode array detector (HPLC-PDA) method and routinely instrument configuration. The carbonic anhydrase (CA, EC 4.2.1.1) inhibition profiles against several pharmacologically relevant CA isoforms of blueberry extracts and some bioactive compounds were also investigated. The various cultivars showed a highly variable content in anthocyanins and chlorogenic acid, and their CA inhibitory effects were also highly variable. Overall these data prove that antioxidant natural products found in blueberries may be useful for designing pharmacological agents in which various CAs are involved, e.g., antiobesity, antitumor, or anticonvulsants agents.     

Synthesis of some tetrahydropyrimidine-5-carboxylates,determination of their metal chelating effects and inhibition profiles against acetylcholinesterase,butyrylcholinesterase and carbonic anhydrase

2-(Methacryloyloxy)ethyl 6-methyl-2-oxo-4-phenyl-1,2,3,4-tetrahydropyrimidine-5-carboxylate, is a cyclic urea derivative synthesized from urea, 2-(methacryloyloxy) ethyl acetoacetate and substituted benzaldehyde, and tested in terms of the inhibition of two physiologically relevant carbonic anhydrase (CA) isozymes I and II. Acetylcholinesterase (AChE) is found in high concentrations in the red blood cells and brain. Butyrylcholinesterase (BChE) is another enzyme abundantly present in the liver and released into blood in a soluble form. Also, they were tested for the inhibition of AChE and BChE enzymes and demonstrated effective inhibition profiles with Ki values in the range of 429.24–530.80?nM against hCA I, 391.86–530.80?nM against hCA II, 68.48–97.19?nM against AChE and 104.70–214.15?nM against BChE. On the other hand, acetazolamide clinically used as CA inhibitor, showed Ki value of 281.33?nM against hCA I, and 202.70?nM against hCA II. Also, Tacrine inhibited AChE and BChE showed Ki values of 396.03 and 209.21?nM, respectively.     

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.     

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.