Indapamide-like benzenesulfonamides as inhibitors of carbonic anhydrases I, II, VII, and XIII

A series of novel 2-chloro-5-[(1-benzimidazolyl- and 2-benzimidazolylsulfanyl)acetyl]benzene-sulfonamides were designed and synthesized. Their binding to recombinant human carbonic anhydrase (hCA) isozymes I, II, VII, and XIII was determined by isothermal titration calorimetry and thermal shift assay. The designed S-alkylated benzimidazole derivatives exhibited stronger binding than the indapamide-like N-alkylated benzimidazoles, with the K(d) reaching about 50-100 nM with drug-targeted hCAs VII and XIII. The cocrystal structures of selected compounds with hCA II were determined by X-ray crystallography, and structural features of the binding event were revealed.     

4-(3-Alkyl/benzyl-guanidino)benzenesulfonamides as selective carbonic anhydrase VII inhibitors

The treatment of chronic neuropathic pain remains one of the most challenging of all neurological diseases and very much an art. There exists no consensus for the optimal management of this condition at the moment. Gaining inspiration from recent studies which pointed out the involvement of brain-associated carbonic anhydrase (CA, EC 4.2.1.1) isoform VII in the pathology of various neurodegenerative diseases, which highlighted the relationship between selective inhibition of this isozyme and relieve of neuropathic pain, herein we report the synthesis and CA VII inhibitory activity of novel 4-(3-alkyl/benzyl-guanidino)benzenesulfonamides. Ten benzyl-substituted and five alkyl-substituted 4-guanidinobenzenesulfonamide derivatives were obtained, some of which (7c, 7h, 7m and 7o) exhibited satisfactory selectivity towards CA VII over CA I and II, with K_I-s in the subnanomolar range and good selectivity indexes for inhibiting the target versus the off-target isoforms.     

4-Substituted-2,3,5,6-tetrafluorobenzenesulfonamides as inhibitors of carbonic anhydrases I,II, VII,XII, and XIII

A series of 4-substituted-2,3,5,6-tetrafluorobenezenesulfonamides were synthesized and their binding potencies as inhibitors of recombinant human carbonic anhydrase isozymes I, II, VII, XII, and XIII were determined by the thermal shift assay, isothermal titration calorimetry, and stop-flow CO₂ hydration assay. All fluorinated benzenesulfonamides exhibited nanomolar binding potency toward tested CAs and fluorinated benzenesulfonamides posessed higher binding potency than non-fluorinated compounds. The crystal structures of 4-[(4,6-dimethylpyrimidin-2-yl)thio]-2,3,5,6-tetrafluorobenzenesulfonamide in complex with CA II and CA XII, and 2,3,5,6-tetrafluoro-4-[(2-hydroxyethyl)sulfonyl]benzenesulfonamide in complex with CA XIII were determined. The observed dissociation constants for several fluorinated compounds reached subnanomolar range for CA I isozyme. The affinity and the selectivity of the compounds towards tested isozymes are presented.     

Discovery of new ureido benzenesulfonamides incorporating 1,3,5-triazine moieties as carbonic anhydrase I,II, IX and XII inhibitors

A series of twenty novel ureido benzenesulfonamides incorporating 1,3,5-triazine moieties substituted on one side with aromatic amines and on the other side with dimethylamine, morpholine and piperidine is reported. The compounds were synthesized from the 4-(3-(4,6-dichloro-1,3,5-triazin-2-yl)ureido)benzensulfonamide (1) by using stepwise nucleophilic substitution of the chlorine atoms of cyanuric chloride. The intermediates 2(a-e) and final compounds 3(a-o) were tested for their efficiency as carbonic anhydrase (CA) inhibitors against four selected physiologically relevant human carbonic anhydrase (CA, EC 4.2.1.1) isoforms, namely, the cytosolic ones hCA I and II, and the transmembrane, tumor associated ones hCA IX, and XII. The compounds 2a, 2e and 3m showed the highest activity for hCA IX with K_is in the range of 11.8–14.6?nM. Most of the compounds showed high hCA IX selectivity over the abundant off-target isoforms hCA I and II. Since hCA IX is a validated drug target for anticancer/antimetastatic agents, these isoform-selective and potent inhibitors may be considered of interest for further medicinal/pharmacologic studies.     

Benzenesulfonamides with benzimidazole moieties as inhibitors of carbonic anhydrases I,II, VII,XII and XIII

Abstract

A series of benzenesulfonamide derivatives, bearing benzimidazole moieties, were designed and synthesized as inhibitors of carbonic anhydrases (CAs). Their binding affinities to recombinant human CA isozymes I, II, VII, XII and XIII were determined by the thermal shift assay. A group of compounds containing a benzimidazole substituent in the para position of the benzenesulfonamide ring was found to exhibit higher binding potency toward tested CAs than meta-substituted benzenesulfonamides. Some of these compounds exhibited nanomolar affinities and selectivity toward the CA isozymes tested.     

First evaluation of organotellurium derivatives as carbonic anhydrase I,II, IV,VII and IX inhibitors

A series of tellurides was evaluated as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors against the human (h) carbonic anhydrase isoforms hCA I, II, IV, VII and IX, involved in a variety of diseases, including glaucoma, retinitis pigmentosa, epilepsy, arthritis and tumors. These compounds, which are the first tellurium-containing derivatives acting as inhibitors of carbonic anhydrase enzymes, showed effective inhibition against all isoforms investigated and some of them were selective for inhibiting the cytosolic or the membrane-bound CAs. Thus, these carbonic anhydrase inhibitors are interesting leads for the development of isoform-selective inhibitors.     

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.     

Carbonic anhydrase inhibitors: inhibition of cytosolic/tumor-associated carbonic anhydrase isozymes I, II, and IX with benzo[b]thiophene 1,1-dioxide sulfonamides

A series of selected benzo[b]thiophene-5- and 6-sulfonamide derivatives previously reported to show cytotoxic activity and some others newly synthesized has been tested for the interactions with several CA isozymes, some of which are known to be involved in tumorigenesis (hCA IX), whereas others are ubiquitously found in many normal tissues (the cytosolic isoforms hCA I and II). The unsubstituted sulfonamides inhibited hCA I with inhibition constants in the range of 63-138 nM, hCA II with inhibition constants in the range of 6.3-8.8 nM, and hCA IX with inhibition constants in the range of 2.8-15 nM, being thus more active than clinically used inhibitors such as acetazolamide, methazolamide, ethoxzolamide, dichlorophenamide or indisulam (E 7070). Some of these derivatives also showed some selectivity for the inhibition of the tumor-associated (hCA IX) over the cytosolic isozyme hCA II. Although these derivatives may act on many targets other than the CAs (such as the NADH oxidase) or may induce apoptosis by accumulation of reactive oxygen species, it is quite important to try to decipher as many as possible of the potential mechanisms that lead to derivatives with potent antitumor activity in order to develop novel therapeutic strategies for the management of cancer.     

Carbonic anhydrase inhibitors: novel sulfonamides incorporating 1,3,5-triazine moieties as inhibitors of the cytosolic and tumour-associated carbonic anhydrase isozymes I, II and IX

A new series of aromatic benzenesulfonamides incorporating 1,3,5-triazine moieties in their molecules is reported. This series was obtained by reaction of cyanuric chloride with sulfanilamide, homosulfanilamide or 4-aminoethylbenzenesulfonamide. The prepared dichlorotriazinyl-benzenesulfonamides were subsequently derivatized by reacting them with various nucleophiles, such as ammonia, hydrazine, primary and secondary amines, amino acid derivatives or phenol. The library of sulfonamides incorporating triazinyl moieties was tested for the inhibition of three physiologically relevant carbonic anhydrase (CA, EC 4.2.1.1) isozymes, the cytosolic hCA I and II, and the transmembrane, tumour-associated hCA IX. The new compounds inhibited hCA I with inhibition constants in the range of 31-8500 nM, hCA II with inhibition constants in the range of 14-765 nM and hCA IX with inhibition constants in the range of 1.0-640 nM. Structure-activity relationship was straightforward and rather simple in this class of CA inhibitors, with the compounds incorporating compact moieties at the triazine ring (such as amino, hydrazino, ethylamino, dimethylamino or amino acyl) being the most active ones, and the derivatives incorporating such bulky moieties (n-propyl, n-butyl, diethylaminoethyl, piperazinylethyl, pyridoxal amine or phenoxy) being less effective hCA I, II and IX inhibitors. Some of the new derivatives also showed selectivity for inhibition of hCA IX over hCA II (selectivity ratios of 23.33-32.00), thus constituting excellent leads for the development of novel approaches for the management of hypoxic tumours.     

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.     

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,biological evaluation and computational studies of novel iminothiazolidinone benzenesulfonamides as potent carbonic anhydrase II and IX inhibitors

A series of iminothiazolidinone-sulfonamide hybrids (2a-k) was synthesized by heterocyclization of sulfanilamide thioureas with methyl bromoacetate and characterized by spectroscopic techniques, mass and elemental analysis. The synthesized derivatives were screened against four relevant human (h) isoforms of carbonic anydrases (CAs, EC 4.2.1.1) I, II, IV and IX. These enzymes are involved in a variety of diseases, including glaucoma, retinitis pigmentosa, epilepsy, arthritis, and tumors. Derivatives 2a-2k exhibited the best inhibitory activity against the cytosolyc hCA II (K_Is are reaching the sub-nanomolar range, 0.41–37.8 nM) and against the tumor-associated isoform hCA IX (K_Is are spanning between 24.3 and 368.3 nM). The binding mode of the reported iminothiazolidinone benzenesulfonamides within hCA II and IX catalytic clefts was investigated by docking studies.     

4-Anilinoquinazoline-based benzenesulfonamides as nanomolar inhibitors of carbonic anhydrase isoforms I,II, IX,and XII: design,synthesis, in-vitro,and in-silico biological studies

Human carbonic anhydrase inhibitors (hCAIs) are a key therapeutic class with a multitude of novel applications such as anticonvulsants, topically acting antiglaucoma, and anticancer drugs. Herein, a new series of 4-anilinoquinazoline-based benzenesulfonamides were designed, synthesised, and biologically assessed as potential hCAIs. The target compounds are based on the well-tolerated kinase scaffold (4-anilinoquinazoline). Compounds 3a (89.4 nM), 4e (91.2 nM), and 4f (60.9 nM) exhibited 2.8, 2.7, and 4 folds higher potency against hCA I when compared to the standard (AAZ, V), respectively. A single digit nanomolar activity was elicited by compounds 3a (8.7 nM), 4a (2.4 nM), and 4e (4.6 nM) with 1.4, 5, and 2.6 folds of potency compared to AAZ (12.1 nM) against isoform hCA II, respectively. Structure-activity relationship (SAR) and molecular docking studies validated our design approach that revealed highly potent hCAIs.     

Benzenesulfonamides with pyrimidine moiety as inhibitors of human carbonic anhydrases I,II, VI,VII, XII,and XIII

Two groups of benzenesulfonamide derivatives, bearing pyrimidine moieties, were designed and synthesized as inhibitors of carbonic anhydrases (CA). Their binding affinities to six recombinant human CA isoforms I, II, VI, VII, XII, and XIII were determined by the thermal shift assay (TSA). The binding of several inhibitors was measured by isothermal titration calorimetry (ITC). Direct demonstration of compound inhibition was achieved by determining the inhibition constant by stopped-flow CO₂ hydration assay. The most potent compounds demonstrated selectivity towards isoform I and affinities of 0.5 nM. The crystal structures of selected compounds in complex with CA II, XII, and XIII were determined to atomic resolution. Compounds described here were compared with previously published pyrimidinebenzenesulfonamides.¹ Systematic structure–activity analysis of 40 compound interactions with six isoforms yields clues for the design of compounds with greater affinities and selectivities towards target CA isoforms.     

Carbonic anhydrase inhibitors: synthesis and inhibition of cytosolic/tumor-associated carbonic anhydrase isozymes I, II, and IX with bis-sulfamates

A series of bis-sulfamates incorporating aliphatic, aromatic, or betulinyl moieties in their molecules was obtained by reaction of the corresponding diols/diphenols with sulfamoyl chloride. The library of bis-sulfamates thus obtained was tested for the inhibition of three physiologically relevant human carbonic anhydrase (hCA, EC 4.2.1.1) isozymes, the cytosolic hCA I and II, and the transmembrane, tumor-associated hCA IX. The new compounds reported here inhibited hCA I with K(I) s in the range of 79 nM-16.45 microM, hCA II with K(I) s in the range of 6-643 nM, and hCA IX with K(I) s in the range of 4-5400 nM. Several low nanomolar hCA IX inhibitors were detected, such as 1,8-octylene-bis-sulfamate or 1,10-decylene-bis-sulfamate (K(I) s in the range of 4-7 nM), which showed good selectivity ratios (in the range of 3.50-3.85) for hCA IX over hCA II inhibition. The most selective hCA IX inhibitor was phenyl-1,4-dimethylene-bis-sulfamate (K(I) of 61.6 nM), which was a 10.43 times better hCA IX than hCA II inhibitor. These derivatives are interesting candidates for the development of novel antitumor therapies targeting hypoxic tumors, since hCA IX is highly overexpressed in such tissues, and its presence is correlated with bad prognosis and unfavorable clinical outcome.     

Carbonic anhydrase inhibitors: synthesis and inhibition of cytosolic/tumor-associated carbonic anhydrase isozymes I, II, and IX with sulfonamides derived from 4-isothiocyanato-benzolamide

A series of sulfonamides incorporating 4-thioureido-benzolamide moieties have been prepared from aminobenzolamide and thiophosgene followed by the reaction of the thiocyanato intermediate with aliphatic/aromatic amines or hydrazines. The new derivatives have been investigated as inhibitors of the zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1), and more precisely of the cytosolic isozymes hCA I and II, as well as the tumor-associated isozyme hCA IX (all of human origin). The new compounds showed excellent inhibitory properties against all three isozymes with inhibition constants in the range of 0.6-62 nM against hCA I, 0.5-1.7 nM against hCA II and 3.2-23 nM against hCA IX, respectively. These derivatives are interesting candidates for the development of novel therapies targeting hypoxic tumors.     

Effects of dopaminergic compounds on carbonic anhydrase isozymes I, II, and VI

Studies on carbonic anhydrase (CA, EC 4.2.1.1) inhibitors have increased due to several therapeutic applications while there are few investigations on activators. Here we investigated CA inhibitory and activatory capacities of a series of dopaminergic compounds on human carbonic anhydrase (hCA) isozymes I, II, and VI. 2-Amino-1,2,3,4-tetrahydronaphthalene-6,7-diol hydrobromide and 2-amino-1,2,3,4-tetrahydronaphthalene-5,6-diol hydrobromide were found to show effective inhibitory action on hCA I and II whereas 2-amino-5,6-dibromoindan hydrobromide and 2-amino-5-bromoindan hydrobromide exhibited only moderate inhibition against both isoforms, being more effective inhibitors of hCA VI. K(i) values of the molecules 3-6 were in the range of 41.12-363 μM against hCA I, of 0.381-470 μM against hCA II and of 0.578-1.152 μM against hCA VI, respectively. Compound 7 behaved as a CA activator with K(A) values of 27.3 μM against hCA I, of 18.4 μM against hCA II and of 8.73 μM against hCA VI, respectively.     

Effects of dopaminergic compounds on carbonic anhydrase isozymes I,II, and VI

Studies on carbonic anhydrase (CA, EC 4.2.1.1) inhibitors have increased due to several therapeutic applications while there are few investigations on activators. Here we investigated CA inhibitory and activatory capacities of a series of dopaminergic compounds on human carbonic anhydrase (hCA) isozymes I, II, and VI. 2-Amino-1,2,3,4-tetrahydronaphthalene-6,7-diol hydrobromide and 2-amino-1,2,3,4-tetrahydronaphthalene-5,6-diol hydrobromide were found to show effective inhibitory action on hCA I and II whereas 2-amino-5,6-dibromoindan hydrobromide and 2-amino-5-bromoindan hydrobromide exhibited only moderate inhibition against both isoforms, being more effective inhibitors of hCA VI. K_i values of the molecules 3–6 were in the range of 41.12–363 μM against hCA I, of 0.381–470 μM against hCA II and of 0.578–1.152 μM against hCA VI, respectively. Compound 7 behaved as a CA activator with K_A values of 27.3 μM against hCA I, of 18.4 μM against hCA II and of 8.73 μM against hCA VI, respectively.