Isoforms hCA Research Articles

Synthesis, Computational Studies and Assessment of in Vitro Activity of Squalene Derivatives as Carbonic Anhydrase Inhibitors.

We report novel molecules incorporating the nontoxic squalene scaffold and different carbonic anhydrase inhibitors (CAIs). Potent inhibitory action, in the low-nanomolar range, was detected against isoforms hCA II for sulfonamide derivatives, which proved to be selective against this isoform over the tumor-associate hCA IX and XII isoforms. On the other hand, coumarin derivatives showed weak potency but high selectivity against the tumor-associated isoform CA IX. These compounds are interesting candidates for preclinical evaluation in glaucoma or various tumors in which the two enzymes are involved. In addition, an in silico study of inhibitor-bound hCA II revealed extensive interactions with the hydrophobic pocket of the active site and provided molecular insights into the binding properties of these new inhibitors.

Synthesis and biological evaluation of some coumarin hybrids as selective carbonic anhydrase IX and XII inhibitors

Two series, coumarin-linked to thiazolidinone via a pyrazole linker (6a-m, Series 1) and coumarin-linked 1,2,3-triazoles (5a-j, Series 2) were synthesized and the synthesized compounds were subjected for evaluation against the four physiologically and pharmacologically relevant hCA isoforms, hCA I, II, IX and XII. The results indicated selective inhibition of tumor-associated isoforms hCA IX and XII over the off-target isoforms, hCA I and II. The compounds of series 1 exhibited better hCA IX inhibition compared to hCA XII, with compounds 6i, 6h, 6a and 6k, exhibiting notable Ki values of less than 100 nM. Among all the compounds, compound 6i showed the best inhibition with a Ki value of 61.5 nM. Among the compounds of series 2, compounds 5a, 5b, 5c, 5d, 5f and 5j exhibited notable hCA IX inhibition. Compound 5d showed the best inhibition with a Ki value of 32.7 nM. In the case of hCA XII, compound 5i showed the best inhibition with a Ki value of 84.2 nM. Hence, compound 6i from Series 1 and 5d from Series 2 could be taken as lead compounds for the further development of selective and potent hCA IX inhibitors, whereas the compound 5i from Series 2 can be explored further for the design of selective and potent hCA XII inhibitors.

In Silico-Guided Identification of New Potent Inhibitors of Carbonic Anhydrases Expressed in Vibrio cholerae.

Carbonic anhydrases from Vibrio cholerae (VchCAs) play a significant role in bacterial pathophysiological processes. Therefore, their inhibition leads to a reduction of gene expression virulence and bacterial growth impairment. Herein, we report the first ligand-based pharmacophore model as a computational tool to study selective inhibitors of the β-class of VchCA. By a virtual screening on a collection of sulfonamides, we retrieved 9 compounds that were synthesized and evaluated for their inhibitory effects against VchCAβ as well as α- and γ-classes of VchCAs and selectivity over human ubiquitous isoforms hCA I and II. Notably, all tested compounds were active inhibitors of VchCAs. The N-(4-sulfamoylbenzyl)-[1,1'-biphenyl]-4-carboxamide (20e) stood out as the most exciting inhibitor toward the β-class (K i = 95.6 nM), also showing a low affinity against the tested human isoforms. By applying docking procedures, we described the binding mode of the inhibitor 20e within the catalytic cavity of the modeled open conformation of VchCAβ.

3-Methylthiazolo[3,2-a]benzimidazole-benzenesulfonamide conjugates as novel carbonic anhydrase inhibitors endowed with anticancer activity: Design, synthesis, biological and molecular modeling studies.

Herein we describe design and synthesis of different series of novel small molecules featuring 3-methylthiazolo[3,2-a]benzimidazole moiety (as a tail) connected to the zinc anchoring benzenesulfonamide moiety via ureido (7), enaminone (12), hydrazone (14), or hydrazide (15) linkers. The newly prepared conjugates have been screened for their inhibitory activities toward four human (h) carbonic anhydrase (CA, EC 4.2.1.1) isoforms: hCA I, II, IX and XII. Thereafter, the urea and enaminone linkers were elongated by one- or two-atoms spacers to afford the elongated counterparts 9 and 13, respectively. Finally, the zinc anchoring sulfonamide group was replaced by the carboxylic acid group to afford acids 17. Compounds 12d, 13b and 15 displayed single-digit nanomolar CA IX inhibitory activities (KIs=6.2, 9.7 and 5.5nM, respectively), along with good selectivity towards hCA IX over hCA I and II. Subsequently, they were screened for their growth inhibitory actions against breast cancer MCF-7 and MDA-MB-231cell lines, and for their impact on cell cycle progression and induction of apoptosis. Moreover, a molecular docking study was conducted to gain insights for the plausible binding interactions of target sulfonamides within hCA isoforms II, IX and XII binding sites.

New coumarin/sulfocoumarin linked phenylacrylamides as selective transmembrane carbonic anhydrase inhibitors: Synthesis and in-vitro biological evaluation

Two novel series of phenylacrylamide linked coumarins and sulfocoumarins (6a-p, 8a-i, and 14a-g) were synthesized and evaluated against four physiologically relevant human carbonic anhydrases (hCAs, EC 4.2.1.1), isoforms hCA I, hCA II, hCA IX and hCA XII for their inhibitory action. All new compounds when screened for carbonic anhydrase inhibitory activity have shown selective inhibition towards the tumor associated isoforms hCA IX and XII over CA I and II, with inhibition constants in the submicromolar to low nanomolar range. Compound 6b and 14g exhibited significant inhibition with low nanomolar potency against hCA IX, whereas 6k was effective against hCA XII. Compounds 6b, 14g and 6k may be considered as lead molecules for future development of cancer therapeutics based on a novel mechanism of action.

Design, Synthesis, and Biological Evaluation of 1,2,3-Triazole-Linked Triazino[5,6-B]Indole-Benzene Sulfonamide Conjugates as Potent Carbonic Anhydrase I, II, IX, and XIII Inhibitors.

A series of 1,2,3-triazole-linked triazino[5,6-b]indole-benzene sulfonamide hybrids (6a–6o) was synthesized and evaluated for carbonic anhydrase (CA, EC 4.2.1.1) inhibitory activity against the human (h) isoforms hCA I, II, XIII (cytosolic isoforms), and hCA IX (transmembrane tumor-associated isoform). The results revealed that the compounds 6a–6o exhibited Ki values in the low to medium nanomolar range against hCA II and hCA IX (Kis ranging from 7.7 nM to 41.3 nM) and higher Ki values against hCA I and hCA XIII. Compound 6i showed potent inhibition of hCA II (Ki = 7.7nM), being more effective compared to the standard inhibitor acetazolamide (AAZ) (Ki = 12.1 nM). Compounds 6b and 6d showed moderate activity against hCA XIII (Ki = 69.8 and 65.8 nM). Hence, compound 6i could be consider as potential lead candidate for the design of potent and selective hCA II inhibitors.

Synthesis, bioactivity and binding energy calculations of novel 3-ethoxysalicylaldehyde based thiosemicarbazone derivatives.

In recent decade, the entrance of α-N-heterocyclic thiosemicarbazones derivates (Triapne, COTI-2 and DpC) in clinical trials for cancer and HIV-1 has vastly increased the interests of medicinal chemists towards this class of organic compounds. In the given study, a series of eighteen new (3a-r) 3-ethoxy salicylaldehyde-based thiosemicarbazones (TSC), bearing aryl and cycloalkyl substituents, were synthesized and assayed for their pharmacological potential against carbonic anhydrases (hCA I and hCA II), cholinesterases (AChE and BChE) and α-glycosidase. The hCA I isoform was inhibited by these novel 3-ethoxysalicylaldehyde thiosemicarbazone derivatives (3a-r) in low nanomolar levels, the Ki of which differed between 144.18±26.74 and 454.92±48.32nM. Against the physiologically dominant isoform hCA II, the novel compounds demonstrated Kis varying from 110.54±14.05 to 444.12±36.08nM. Also, these novel derivatives (3a-r) effectively inhibited AChE, with Ki values in the range of 385.38±45.03 to 983.04±104.64nM. For BChE was obtained with Ki values in the range of 400.21±35.68 to 1003.02±154.27nM. For α-glycosidase the most effective Ki values of 3l, 3n, and 3q were with Ki values of 12.85±1.05, 16.03±2.84, and 19.16±2.66nM, respectively. Moreover, the synthesized TCSs were simulated using force field methods whereas the binding energies of the selected compounds were estimated using MM-GBSA method. The findings indicate the present novel 3-ethoxy salicylaldehyde-based thiosemicarbazones to be excellent hits for pharmaceutical applications.

Development of oxathiino[6,5-b]pyridine 2,2-dioxide derivatives as selective inhibitors of tumor-related carbonic anhydrases IX and XII

Oxathiino[6,5-b]pyridine 2,2-dioxides are identified as a new class of isoform-selective nanomolar inhibitors of tumor associated human carbonic anhydrases (hCA) IX and XII. At the same time they do not inhibit or poorly inhibit cytosolic isoforms hCA I and II. Oxathiino[6,5-b]pyridine 2,2-dioxides exhibited good antiproliferative properties on tumor cell lines MCF-7 (Human breast adenocarcinoma), A549 (human lung (alveolar) adenocarcinoma) and HeLa (epithelioid cervix carcinoma).

N-aryl-N'-ureido-O-sulfamates as potent and selective inhibitors of hCA VB over hCA VA: Deciphering the binding mode of new potential agents in mitochondrial dysfunctions.

N-aryl-N'-ureido-O-sulfamates (AUSs) were recently reported as new class of Carbonic Anhydrase Inhibitors (CAIs), endowed of high potency and selectivity against hCA VII and XII. In this work, we extended the investigational study on this new class of CAIs profiling them against the mitochondrial CA isoforms hCA VA and VB. The results revealed a very interesting selectivity profile, with dramatic selectivity against hCA VB over the VA isoform observed for all the analyzed compounds 2-22. On derivative 15, selected as one of the most promising among the series, molecular modeling studies were conducted, highlighting the importance of small residue substitution between the two isoforms in substantially changing the tail orientation and interaction with the enzymes.

Benzoxepinones: A new isoform-selective class of tumor associated carbonic anhydrase inhibitors

Benzoxepinones (“homocoumarins”) are identified as a new class of selective inhibitors for tumor associated human carbonic anhydrases (hCA, EC 4.2.1.1) isoforms IX and XII. Similar to coumarins, they do not inhibit or poorly inhibit cytosolic human (h) isoforms hCA I and II, but act as nanomolar inhibitors of the trans-membrane, tumor associated isoforms hCA IX and XII.

Sulfonamides incorporating ketene N,S-acetal bioisosteres as potent carbonic anhydrase and acetylcholinesterase inhibitors.

In this study, 15 novel compounds in a series of sulfonamide-based ketenes (7a-o) were synthesized and characterized using Fourier-transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and mass spectrometry. All compounds were tested for their ability to inhibit the human carbonic anhydrase (hCA) isoforms I and II, and acetylcholinesterase (AChE). The halogen-appended compounds, 7g, 7o, and 7i, exhibited the highest hCA I/II and AChE inhibition, with the KI values in the low nanomolar range (KI = 9.01 ± 0.08, 7.41 ± 0.03, and 7.37 ± 0.31 nM, respectively), as compared with their corresponding parent 2-[2,2-dicyano-1-(phenylamino)vinylthio]-N-(4-sulfamoylphenyl)acetamide analogs 7a-o. Besides, derivatives 7c and 7e selectively inhibited the isoform hCA I, whereas compounds 7m and 7n selectively inhibited isoform hCA II. These findings indicated that all compounds can inhibit metabolic dysfunctions, such as edema, epilepsy, glaucoma, and Alzheimer's disease, by specifically targeting both the hCA isoforms and AChE expression. Herein, also the interactions between ligands and receptors were highlighted through in silico molecular docking studies. The molecular mechanics-generalized Born surface area method was utilized to compute the binding free energy and the energy contribution of the critical residues in the active site was estimated. All these results would help us to perfectly understand the relationship between activity and structural characteristics of derivatives and to further improve newly and highly effective analogs targeting hCA and AChE.

Synthesis and carbonic anhydrase inhibition studies of sulfonamide based indole-1,2,3-triazole chalcone hybrids.

Sulfonamide is one of the most promising classes of classical carbonic anhydrase (CA, EC 4.2.1.1) inhibitors. A novel series of indolylchalcones incorporating benzenesulfonamide-1,2,3-triazole (6a-q) has been synthesized by click chemistry reaction and investigated for hCA inhibitory activity against a panel of human carbonic anhydrases (hCAs). Most of these newly synthesized compounds exhibited interesting inhibition constants, in the nanomolar range, with some derivatives being more potent than the standard drug acetazolamide (AAZ) on hCA I isoform. Among the tested compounds, the compounds 6d (18.8nM), 6q (38.3nM) and 6e (50.4nM) were 13, 6 and 5 times more potent than AAZ against hCA I isoform, respectively. Compounds 6o, 6m and 6f efficiently inhibited isoform hCA XII, with KIs in the range of 10-41.9nM. Several compounds were also active against isoforms hCA II and hCA IX, with KIs under 100nM. These indolylchalcone-benzenesulfonamide-1,2,3-triazole hybrids may be considered as potential leads for hCA I-selective inhibitors.

Synthesis and Biological Evaluation of Imidazo[2 ,1-b]Thiazole based Sulfonyl Piperazines as Novel Carbonic Anhydrase II Inhibitors.

A novel series of imidazo[2,1-b]thiazole-sulfonyl piperazine conjugates (9aa-ee) has been synthesized and evaluated for carbonic anhydrase (CA, EC 4.2.1.1) inhibitory potency against four isoforms: The cytosolic isozyme hCA I, II and trans-membrane tumor-associated isoform hCA IX and hCA XII, taking acetazolamide (AAZ) as standard drug, using a stopped flow CO2 hydrase assay. The results revealed that most of the compounds showed selective activity against hCA II whereas none of them were active against hCA I, IX, XII (Ki > 100 µM). The physiologically dominant cytosolic isoform hCA II was inhibited by these molecules with inhibition constants in the range of 57.7–98.2 µM. This new derivative, thus, selectively inhibits hCA II over the hCA I, IX, XII isoforms, which may be used for further understanding the physiological roles of some of these isoforms in various pathologies.

Benzofuran-Based Carboxylic Acids as Carbonic Anhydrase Inhibitors and Antiproliferative Agents against Breast Cancer.

Pursuing our effort for developing effective inhibitors of the cancer-related hCA IX isoform, here we describe the synthesis of novel benzofuran-based carboxylic acid derivatives, featuring the benzoic (9a-f) or hippuric (11a,b) acid moieties linked to 2-methylbenzofuran or 5-bromobenzofuran tails via an ureido linker. The target carboxylic acids were evaluated for the potential inhibitory action against hCAs I, II, IX, and XII. Superiorly, benzofuran-containing carboxylic acid derivatives 9b, 9e, and 9f acted as submicromolar hCA IX inhibitors with KIs = 0.91, 0.79, and 0.56 μM, respectively, with selective inhibitory profile against the target hCA IX over the off-target isoforms hCA I and II (SIs: 2 to >63 and 4-47, respectively). Compounds 9b, 9e, and 9f were examined for their antiproliferative action against human breast cancer (MCF-7 and MDA-MB-231) cell lines. In particular, 9e displayed promising antiproliferative (IC50 = 2.52 ± 0.39 μM), cell cycle disturbance, and pro-apoptotic actions in MDA-MB-231 cells.

Novel functionally substituted esters based on sodium diethyldithiocarbamate derivatives: Synthesis, characterization, biological activity and molecular docking studies.

Alkylation of sodium diethyldithiocarbamate with allyl-2-chloroacetate, allyl-3-chloropropionate, chloromethyl-2-(tetrahydrofuran-2-yl)acetate, and 4-(chloromethyl)-1,3-dioxolane in the aqueous medium synthesized functionally substituted esters of N, N-dietyleditiocarbamic acid (M1-M4). Most active compounds were docked into the catalytic active site of the enzyme. We identified that acetate moiety for inhibition of hCA I, hCA II, and α-glycosidase and dioxolane and thiocarbamic acid moieties for inhibition of AChE and BChE enzymes are very important. The hCA I isoform was inhibited by these novel functionally substituted esters based on sodium diethyldithiocarbamate derivatives (M1-M4) in low micromolar levels, the Ki of which differed between 48.03±9.77 and 188.42±46.08µM. Against the physiologically dominant isoform hCA II, the novel compounds demonstrated Kis varying from 57.33±6.21 to 174.34±40.72µM. Also, these novel derivatives (M1-M4) effectively inhibited AChE, with Ki values in the range of 115.42±12.44 to 243.22±43.65µM. For BChE Ki values were found in the range of 94.33±9.14 to 189.45±35.88µM. For α-glycosidase the most effective Ki values of M4 and M3 were with Ki values of 32.86±7.88 and 37.63±4.08µM, respectively.

Tail approach synthesis of novel benzenesulfonamides incorporating 1,3,4-oxadiazole hybrids as potent inhibitor of carbonic anhydrase I, II, IX, and XII isoenzymes

Two new series of 1,3,4-oxadiazole benzenesulfonamide hybrids 3 and 4, having twenty novel compounds, have been designed and synthesized in order to assess their inhibition potential as CAIs against hCA I, II, IX, and XII. ‘Tail approach’ strategy has been used to design the aromatic sulfonamide scaffolds with carbonyl and amide linker. Excellent inhibitory activity against hCA I has been exhibited by compounds 3g and 4j, 3.5 magnitude of order better than reference drug AAZ (KI = 250 nM). Moreover, compound 4j (KI = 7.9 nM) effectively inhibited glaucoma-associated hCA II isoform as well as tumor-associated hCA IX isoform with KI = 16.3 nM. Further hCA XII was weakly inhibited by all the compounds with KI values ranging from 0.23 μM to 3.62 μM. Interestingly structure-activity relationship (SAR) study indicates that N-(3-nitrophenyl)-2-((5-(4-sulfamoylphenyl)-1,3,4-oxadiazol-2-yl)thio)acetamide (4j) is a potent compound to be investigated further for antiglaucoma and antitumor activity. The chemistry of the nature of different substitutions on the 1,3,4-oxadiazole bearing benzenesulfonamide substituted aromatic ring for potency and selectivity over one hCA isoform versus others is deliberated in the present study. In this context, the 1,3,4-oxadiazole motif can be a valuable tool worth developing for the procurement of novel and potent selective CAIs potentially useful for the management of a variety of diseases as chemotherapeutic agents.

Design, synthesis and biological evaluation of coumarin linked 1,2,4-oxadiazoles as selective carbonic anhydrase IX and XII inhibitors.

A series of coumarin linked 1,2,4-oxadiazoles were synthesized and the synthesized compounds were subjected for evaluation against the four physiologically and pharmacologically relevant hCA isoforms, hCA I, II, IX and XII. Upon evaluation of the results, it was inferred that the coumarin linked 1,2,4-oxadiazoles showed selective hCA IX and XII inhibition (low to medium nanomolar range) over hCA I and II (>10000nM). The inhibition constants ranged from low nanomolar to moderately nanomolar. Compounds 6o, 6a, 6q and 6c elicited hCA XII inhibition, with Ki values lower than that of the standard, Acetazolamide (AAZ) with compound 6o exhibiting a Ki value of 1nM., against hCA IX, the compound 6c exhibited the most potent inhibition with a Ki value of 23.6nM. Hence, compound 6o can be taken as an effective lead compound for the development of hCA XII inhibitors and compound 6c can be taken as a lead compound for the development of dual hCA IX and XII inhibitors. To understand the molecular interactions, the two most potent compounds 6a and 6o were docked within the hCA XII catalytic cleft in order to study their binding modes with that isoform.

Activation Effects of Carnosine- and Histidine-Containing Dipeptides on Human Carbonic Anhydrases: A Comprehensive Study.

l-Carnosine (β-Ala-l-His) and several other histidine-containing peptides, including two N-methylated forms on the imidazole ring (l-anserine and l-balenine), two derivatives modified on the carboxyl function (carcinine and l-carnosinamide), two analogues differing in the length of the N-terminal residue (l-homocarnosine and Gly-l-His) and the N-acetyl derivatives, were investigated as activators of four isoforms of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). The four human isoforms hCA I, II, VA and IX were activated in the low to high micromolar range, with a rather complex structure activity relationship. A performed computational study allowed us to rationalize these results and to propose a binding mode of these activators within the enzyme active site. Similarly to other CA activators, the here studied peptides could find relevant pharmacological applications such as in the management of CA deficiencies, for therapy memory and enhancing cognition or for artificial tissues engineering.

New thiopyrimidine-benzenesulfonamide conjugates as selective carbonic anhydrase II inhibitors: synthesis, in vitro biological evaluation, and molecular docking studies

In the present work, a new series of thiopyrimidine-benzenesulfonamide conjugates was designed, synthesized and tested as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors. Our design strategy was based on the molecular hybridization of the benzenesulfonamide moiety as a zinc binding group (ZBG), an alkylated thiopyrimidine moiety as a spacer and (un)substituted phenyl moieties with various electronic and hydrophobic environments as a tail. The designed and synthesized compounds were evaluated against four human (h) CA isoforms hCA I, hCA II, hCA IX and hCA XII. Series 6 showed promising activity and selectivity toward the cytosolic isoforms hCA I and hCA II versus the membrane bound isoforms hCA IX and hCA XII. Compounds 6e and 6f showed Ki of 0.04 µM against hCA II with a selectivity of 15.8- to 980-fold towards hCA II over hCA I, hCA IX, hCA XII isoforms. Molecular docking in the hCA II active site attributed the promising inhibitory activity of series 6 to the interaction of their sulfonamide moiety with the active site Zn2+ ion as well as its hydrogen bonding with the key amino acids Thr199 and Thr200. Through hydrophobic interaction, the benzenesulfonamide and the thiopyrimidine moieties interact with the hydrophobic side chains of the amino acids Val121/Leu198 and Ile91/Phe131, respectively. These results indicated that the designed and synthesized series is an interesting scaffold that can be further optimized for the development of selective antiglaucoma drugs.

Sulfonamide-based ring-fused analogues for CAN508 as novel carbonic anhydrase inhibitors endowed with antitumor activity: Design, synthesis, and in vitro biological evaluation

In the present study, we report the design and synthesis of novel CAN508 sulfonamide-based analogues (4, 8a-e, 9a-h and 10a-e) as novel carbonic anhydrase (CA) inhibitors with potential CDK inhibitory activity. A bioisosteric replacement approach was adopted to replace the phenolic OH of CAN508 with a sulfamoyl group to afford compound 4. Thereafter, a ring-fusion approach was utilized to furnish the 5/5 fused imidazopyrazoles 8a-e which were subsequently expanded to 6/5 pyrazolopyrimidines 9a-h and 10a-e. All the synthesized analogues were evaluated for their inhibitory activity toward isoforms hCA I, II, IX and XII. The target tumor-associated isoforms hCA IX and XII were effectively inhibited with KIs ranges 6–67.6 and 10.1–88.6 nM, respectively. Furthermore, all compounds were evaluated for their potential CDK2 and 9 inhibitory activities. Pyrazolopyrimidines 9d, 9e and 10b displayed weak CDK2 inhibitory activity (IC50 = 6.4, 8.0 and 11.6 μM, respectively), along with abolished CDK9 inhibitory activity. This trend suggested that pyrazolopyrimidine derivatives merit further optimization to furnish more effective CDK2 inhibitor lead. On account of their excellent activity and selectivity towards hCA IX and XII, pyrazolopyrimidines 10 were evaluated for their anti-proliferative activity toward breast cancer MCF-7 and MDA-MB-468 cell lines under normoxic and hypoxic conditions. The most potent anti-proliferative agents 10a, 10c and 10d significantly increased cell percentage at sub-G1 and G2-M phases with concomitant decrease in the S phase population in MCF-7 treated cells. Finally, a docking study was undertaken to investigate the binding mode for the most selective hCA IX and XII inhibitors 10a-e, within hCA II, IX and XII active sites.