Carbonic Anhydrase Isoforms Research Articles

Tail-Approach-Based Design and Synthesis of Coumarin-Monoterpenes as Carbonic Anhydrase Inhibitors and Anticancer Agents.

In this study, sixty novel coumarin-monoterpene compounds were synthesized in two series [thirty-two compounds (12-43) bearing a triazole ring in the first series, and twenty-eight compounds (44-71) bearing an alkyl chain in the second one]. Their inhibitory effects on the human carbonic anhydrase (hCA) isoforms I, II, IX, and XII and anticancer potentials were determined. All synthesized molecules selectively inhibited CA IX and XII. 23 and 42 were found to be the strongest inhibitors, with K i values of 1.9 nM against hCA IX. Also, 70 showed the highest inhibitory activity with a K i value of 4.9 nM against hCA XII. Moreover, their cytotoxic effects on colon adenocarcinoma (HT-29), prostate adenocarcinoma (PC-3), and breast adenocarcinoma (MCF-7) cell lines were evaluated. According to the cytotoxicity results, 14 (IC50 = 2.48 μM) and 63 (IC50 = 3.91 μM) exhibited the highest cytotoxicity on the MCF-7 cells, while 23 showed the strongest cytotoxic effect on both PC-3 (IC50 = 9.40 μM) and HT-29 (IC50 = 12.10 μM) cell lines. 14, 23, and 66 decreased CA IX and CA XII protein expression in HT-29 cells, while 23 and 66 showed the strongest reduction of both CA IX and CA XII in MCF-7 cells. All of the selected compounds increased total apoptosis in a concentration-dependent manner in HT-29 and MCF-7 cells. 14 has the strongest apoptotic effect in MCF-7 cells. 23 increased early apoptosis primarily, while 14 and 66 increased total apoptosis in HT-29. In addition, PI/Hoechst staining proves that apoptotic cells are increased in HT-29 with an effect of 14, 23, and 66. As a result of the modeling studies, it has been shown that only the open coumarin form of the compounds can interact directly with the active-site Zn2+ ion. It has been shown that coumarin-monoterpene structures with different alkyl and monoterpene groups both specifically inhibit CA IX and XII and exhibit specific cytotoxicity in different cell lines.

A Series of Trifluoromethylisoxazolyl- and Trifluoromethylpyrazolyl- Substituted (Hetero)aromatic Sulfonamide Carbonic Anhydrase Inhibitors: Synthesis, and Convenient Prioritization Workflow for Further In Vivo Studies.

To synthesize novel sulfonamide inhibitors of carbonic anhydrase and develop in vitro prioritization workflow to select compounds for in vivo evaluation. Carbonic anhydrase (CA) inhibitors gain significant attention in the context of drug discovery research for glaucoma, hypoxic malignancies, and bacterial infections. In previous works, we have successfully used direct sulfochlorination approach to develop diverse heterocyclic primary sulfonamides with remarkable activity and selectivity against therapeutically relevant CA isoforms. Synthesis and investigation of the CA inhibitory properties of novel trifluoromethylisoxazolyl- and trifluoromethylpyrazolyl-substituted (hetero)aromatic sulfonamides. Thirteen trifluoromethylisoxazolyl- and thirteen trifluoromethylpyrazolyl-substituted (hetero) aromatic sulfonamides were synthesized by direct sulfochlorination of hydroxyisoxazolines and pyrazoles followed by reaction with ammonia. The compound structures were confirmed by 1H and 13C NMR as well as element analysis. The obtained compounds were evaluated, using the CA esterase activity assay, for their potential to block the catalytic activity of bovine CA (bCA). Eight most potent compounds selected based on the esterase activity assay data were tested for direct affinity to the enzyme using the thermal shift assay (TSA). These compounds displayed Kd values (measured by TSA) in the double-digit nanomolar range, thus showing comparable activity to the reference drug acetazolamide. Coupling the bCA esterase activity assay with thermal shift assay represents a streamlined and economical strategy for the prioritization of sulfonamide CA inhibitors for subsequent evaluation in vivo.

Derivatives of 4-methyl-1,2,3-benzoxathiazine 2,2-dioxide as selective inhibitors of human carbonic anhydrases IX and XII over the cytosolic isoforms I and II

A series of 4-methyl-1,2,3-benzoxathiazine-2,2-dioxides with various substituents in 5, 6 or 7 positions was obtained from corresponding 2’-hydroxyacetophenones in their reaction with sulphamoyl chloride. 6- and 7-aryl substituted 4-methyl-1,2,3-benzoxathiazine-2,2-dioxides were obtained from aryl substituted 2’-hydroxyacetophenonesprepared from 4- or 5-bromo-2’-hydroxyacetophenones via two-step protocol. 4-Methyl-1,2,3-benzoxathiazine-2,2-dioxides were investigated as inhibitors of four human (h) carbonic anhydrase (hCA, EC 4.2.1.1) isoforms, off-target cytosolic hCA I and II, and target transmembrane, tumour-associated hCA IX and XII. Twenty derivatives of 4-methyl-1,2,3-benzoxathiazine 2,2-dioxide were obtained. With one exception (compound2a), they mostly act as nanomolar inhibitors of target hCA IX and XII. Basically, all screened compounds express none or low inhibitory properties towards off-target hCA I. hCA II is inhibited in micromolar range. Overwhelming majority of 4-methyl-1,2,3-benzoxathiazine 2,2-dioxides express excellent selectivity towards CA IX/XII over hCA I as well as very good selectivity towards CA IX/XII over hCA II.

The effect of pre-exercise alkalosis on lactate/pH regulation and mitochondrial respiration following sprint-interval exercise in humans.

Purpose: The purpose of this study was to evaluate the effect of pre-exercise alkalosis, induced via ingestion of sodium bicarbonate, on changes to lactate/pH regulatory proteins and mitochondrial function induced by a sprint-interval exercise session in humans. Methods: On two occasions separated by 1week, eight active men performed a 3 × 30-s all-out cycling test, interspersed with 20min of recovery, following either placebo (PLA) or sodium bicarbonate (BIC) ingestion. Results: Blood bicarbonate and pH were elevated at all time points after ingestion in BIC vs PLA (p < 0.05). The protein content of monocarboxylate transporter 1 (MCT1) and basigin (CD147), at 6h and 24h post-exercise, and sodium/hydrogen exchanger 1 (NHE1) 24h post-exercise, were significantly greater in BIC compared to PLA (p < 0.05), whereas monocarboxylate transporter 4 (MCT4), sodium/bicarbonate cotransporter (NBC), and carbonic anhydrase isoform II (CAII) content was unchanged. These increases in protein content in BIC vs. PLA after acute sprint-interval exercise may be associated with altered physiological responses to exercise, such as the higher blood pH and bicarbonate concentration values, and lower exercise-induced oxidative stress observed during recovery (p < 0.05). Additionally, mitochondrial respiration decreased after 24h of recovery in the BIC condition only, with no changes in oxidative protein content in either condition. Conclusion: These data demonstrate that metabolic alkalosis induces post-exercise increases in several lactate/pH regulatory proteins, and reveal an unexpected role for acidosis in mitigating the loss of mitochondrial respiration caused by exercise in the short term.

SLC-0111, an inhibitor of carbonic anhydrase IX, attenuates hepatoblastoma cell viability and migration.

In response to hypoxia, tumor cells undergo transcriptional reprogramming including upregulation of carbonic anhydrase (CA) IX, a metalloenzyme that maintains acid-base balance. CAIX overexpression has been shown to correlate with poor prognosis in various cancers, but the role of this CA isoform in hepatoblastoma (HB) has not been examined. We surveyed the expression of CAIX in HB specimens and assessed the impact of SLC-0111, a CAIX inhibitor, on cultured HB cells in normoxic and hypoxic conditions. CAIX immunoreactivity was detected in 15 out of 21 archival pathology HB specimens. The CAIX-positive cells clustered in the middle of viable tumor tissue or next to necrotic areas. Tissue expression of CAIX mRNA was associated with metastasis and poor clinical outcome of HB. Hypoxia induced a striking upregulation of CAIX mRNA and protein in three HB cell models: the immortalized human HB cell line HUH6 and patient xenograft-derived lines HB-295 and HB-303. Administration of SLC-0111 abrogated the hypoxia-induced upregulation of CAIX and decreased HB cell viability, both in monolayer and spheroid cultures. In addition, SLC-0111 reduced HB cell motility in a wound healing assay. Transcriptomic changes triggered by SLC-0111 administration differed under normoxic vs. hypoxic conditions, although SLC-0111 elicited upregulation of several tumor suppressor genes under both conditions. Hypoxia induces CAIX expression in HB cells, and the CAIX inhibitor SLC-0111 has in vitro activity against these malignant cells.

Functional divergence of teleost carbonic anhydrase 4

The functional role of membrane-bound carbonic anhydrases (CAs) has been of keen interest in the past decade, and in particular, studies have linked CA in red muscle, heart, and eye to enhanced tissue oxygen extraction in bony fishes (teleosts). However, the number of purported membrane-bound CA isoforms in teleosts, combined with the imperfect system of CA isoform nomenclature, present roadblocks for ascribing physiological functions to particular CA isoforms across different teleost lineages. Here we developed an organizational framework for membrane-bound CAs in teleosts, providing the latest phylogenetic analysis of extant CA4 and CA4-like isoforms. Our data confirm that there are three distinct isoforms of CA4 (a, b, and c) that are conserved across major teleost lineages, with the exception of CA4c gene being lost in salmonids. Tissue distribution analyses suggest CA4a functions in oxygen delivery across teleost lineages, while CA4b may be specialized for renal acid-base balance and ion regulation. This work provides an important foundation for researchers to elucidate the functional significance of CA4 isoforms in fishes.

Investigation of novel alkyl/benzyl (4-sulphamoylphenyl)carbamimidothioates as carbonic anhydrase inhibitors

A library of novel alkyl/benzyl (4-sulphamoylphenyl)carbamimidothioates was synthesised by selective S-alkylation of the easily accessible 4-thioureidobenzenesulphonamide. The compounds were assayed as inhibitors of four human (h) carbonic anhydrase isoforms hCA I, II, VII, and XIII, as well as three bacterial enzymes belonging to the β-CA class, MscCA from Mammaliicoccus (Staphylococcus) sciuri and StCA1 and StCA2, from Salmonella enterica (serovar Typhimurium). Most compounds investigated here exhibited moderate to low nanomolar inhibition constants against hCA I, II, and VII. The cytosolic hCA XIII was also inhibited by these compounds, but not as effective as hCA I, II, and VII. Several compounds were very effective against MscCA and StCA1. StCA2 was less inhibited compared to MscCA and StCA1. Some compounds showed considerable selectivity for inhibiting some CA isoforms. They may thus be considered as interesting starting points for the discovery and development of novel therapeutic agents belonging to this class of enzyme inhibitors.

Antibiofilm and Anti-Quorum-Sensing Activities of Novel Pyrazole and Pyrazolo[1,5-a]pyrimidine Derivatives as Carbonic Anhydrase I and II Inhibitors: Design, Synthesis, Radiosterilization, and Molecular Docking Studies.

Nowadays, searching for new anti-infective agents with diverse mechanisms of action has become necessary. In this study, 16 pyrazole and pyrazolo[1,5-a]pyrimidine derivatives were synthesized and assessed for their preliminary antibacterial and antibiofilm activities. All these derivatives were initially screened for their antibacterial activity against six clinically isolated multidrug resistance by agar well-diffusion and broth microdilution methods. The initial screening presented significant antibacterial activity with a bactericidal effect for five compounds, namely 3a, 5a, 6, 9a, and 10a, compared with Erythromycin and Amikacin. These five derivatives were further evaluated for their antibiofilm activity against both S. aureus and P. aeruginosa, which showed strong biofilm-forming activity at their MICs by >60%. The SEM analysis confirmed the biofilm disruption in the presence of these derivatives. Furthermore, anti-QS activity was observed for the five hybrids at their sub-MICs, as indicated by the visible halo zone. In addition, the presence of the most active derivatives reduces the violacein production by CV026, confirming that these compounds yielded anti-QS activity. Furthermore, these compounds showed strong inhibitory action against human carbonic anhydrase (hCA-I and hCA-II) isoforms with IC50 values ranging between 92.34 and 168.84 nM and between 73.2 and 161.22 nM, respectively. Finally, radiosterilization, ADMET, and a docking simulation were performed.

Carbonic anhydrases in development: morphological observations and gene expression profiling in sea urchin embryos exposed to acetazolamide.

Carbonic anhydrases (CANs) are conserved metalloenzymes catalysing the reversible hydration of carbon dioxide into protons and bicarbonate, with important roles in cells physiology. Some CAN-coding genes were found in sea urchin genome, although only one involved in embryonic skeletogenesis was described in Paracentrotus lividus. Here, we investigated gene expression patterns of P. lividus embryos cultured in the presence of acetazolamide (AZ), a CAN inhibitor, to combine morphological defects with their molecular underpinning. CAN inhibition blocked skeletogenesis, affected the spatial/temporal expression of some biomineralization-related genes, inhibited embryos swimming. A comparative analysis on the expression of 127 genes in control and 3 h/24 h AZ-treated embryos, using NanoString technology, showed the differential expression of genes encoding for structural/regulatory proteins, with different embryonic roles: biomineralization, transcriptional regulation, signalling, development and defence response. The study of the differentially expressed genes and the signalling pathways affected, besides in silico analyses and a speculative 'interactomic model', leads to predicting the presence of various CAN isoforms, possibly involved in different physiological processes/activities in sea urchin embryo, and their potential target genes/proteins. Our findings provide new valuable molecular data for further studies in several biological fields: developmental biology (biomineralization, axes patterning), cell differentiation (neural development) and drug toxicology (AZ effects on embryos/tissues).

Synthesis, characterization and biological evaluation of pyrazole-based benzene sulfonamides as inhibitors of human carbonic anhydrase II, IX and XII.

The aberrant level of the carbonic anhydrase isozymes is linked with various disorders which include glaucoma, epilepsy, altitude sickness and obesity. In the present study, a series of the pyrazole-based benzene sulfonamides derivatives (4a-4l) were designed, synthesized and evaluated as the inhibitors of the three isoforms of human carbonic anhydrases (hCAII, hCAIX and hCAXII). A number of the derivatives were found more active inhibitors than acetazolamide used as a standard against the human hCAII, hCAIX and hCAXII. Among the series, the compound 4k inhibited the hCAII to a submicromolar level presenting the IC50 ± SEM concentration of 0.24 ± 0.18 μM, the inhibitor 4j reduced the activity of the hCAIX to the IC50 ± SEM equals 0.15 ± 0.07 μM, whereas, the molecule 4g blocked the catalytic potential of the isozyme hCAXII with as low as IC50 concentration of 0.12 ± 0.07 μM. In addition, compounds 4e and 4k were screened as the preferential inhibitors of the isoform hCAXII as compared to the hCAIX and hCAXII with half of the maximal concentrations of 0.75 ± 0.13 μM, and 0.24 ± 0.18 μM, respectively. Moreover, the compounds 4k, 4j and 4g were docked inside the active pocket of the crystallographic structure of the isoforms hCAXII, hCAIX and hCAXII, respectively. The docked inhibitors showed the binding interactions with the important amino acid residues such as Leu1198, Thr1199, His1094, and Phe1131 in hCAXII isozyme; residues Val121, Thr200, Pro203, and Gln71 in hCAIX; the amino acids Val119, Leu197, Gln89, and Asn64 in the case of hCAXII. In addition, structural geometries, reactivity descriptors, optimization energy and electronic parameters were calculated to predict the activity of the synthesized compounds.

Sulfonamides linked to sulfonate estersviahydrazone functionality: synthesis, human carbonic anhydrase inhibitory activities, and molecular modeling studies

A benzenesulfonamide moiety was linked to sulfonate estersviaa hydrazone bridge. The introduction of thep-methoxy group on the terminal phenyl ring led to the most effective inhibitor of tumor-associated human carbonic anhydrase isoforms, hCA IX and XII.

Development of potent nanosized carbonic anhydrase inhibitor for targeted therapy of hypoxic solid tumors

Overexpression of two carbonic anhydrase (CA) isoforms, CA IX and XII, in several hypoxic solid tumors provides an extracellular hypoxic microenvironment, interferes with extra- and intracellular pH regulation, thus favoring hypoxic tumor cell survival, proliferation and metastasis. In the current study, a selective inhibitor for human CA isoforms IX and XII (isatin-bearing sulfonamide, WEG-104), was incorporated into nanosized spherical niosomes at high encapsulation efficiency to allow for an enhanced and sustained antitumor activity. In vivo, administration of WEG-104 that is either free (10 mg/kg) or loaded into niosomes (5 mg/kg) into a mice model of Ehrlich ascites solid tumor resulted in comparable efficacy in terms of reduction of tumor weight and volume. Administration of WEG-104-loaded niosomes (10 mg/kg) exhibited superior antitumor activity compared to the free drug, evidenced by reduced tumor weight and volume, marked reduction in the activity of CA IX and XII, and suppression of HIF-1α and MMP-2. Moreover, prominent increase of caspase 3 and pronounced decrease in VEGF immune expression were observed in the treated animals. Hence, loading of molecularly designed compounds that targets CAs in hypoxic solid tumors into nanosized delivery systems provided an auspicious strategy for limiting solid tumor progression and malignancy.

Schiff bases as linker in the development of quinoline-sulfonamide hybrids as selective cancer-associated carbonic anhydrase isoforms IX/XII inhibitors: A new regioisomerism tactic

A novel set of quinoline tailored with the sulfonamide as zinc-binding group (ZBG) has been rationalized and synthesized as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors. Such hybrids were decorated by a novel elongated imine linker with/without ethylene spacer with variable hydrophobic and lipophilic pockets. Therefore, a regioisomeric tactic has been established, most of which act as efficient inhibitors of the tumor-associated CA isoforms IX and XII. Interestingly, one hybrid 10b displayed an appreciable activity in MCF-7 cell line under normoxic condition (IC50 of 8.42 µM) in comparison to the standard staurosporine (IC50 = 5.34 µM) and excellent activity under hypoxic conditions (IC50 = 1.56 µM) in comparison to staurosporine (IC50 = 4.45 µM). Furthermore, hybrids 8a and 10b encouraged MCF-7 and MDA-MB-231 cell apoptosis alongside promising Bax/Bcl expression ratio change. Docking studies were also, performed and agreed with the biological results. Our SAR study suggested that our regiosiomerization tactic for the quinoline based-sulfonamide molecules led to effective inhibition of tumuor-relevant hCAs IX/XII.

Indoline-5-Sulfonamides: A Role of the Core in Inhibition of Cancer-Related Carbonic Anhydrases, Antiproliferative Activity and Circumventing of Multidrug Resistance.

The overexpression and activity of carbonic anhydrase (CA, EC 4.2.1.1) isoforms CA IX and CA XII promote the accumulation of exceeding protons and acidosis in the extracellular tumor environment. Sulfonamides are effective inhibitors of most families of CAs. In this study, using scaffold-hopping, indoline-5-sulfonamide analogs 4a-u of the CA IX-selective inhibitor 3 were designed and synthesized to evaluate their biological properties. 1-Acylated indoline-5-sulfonamides demonstrated inhibitory activity against tumor-associated CA IX and XII with KI values up to 132.8 nM and 41.3 nM. Compound 4f, as one of the most potent inhibitors of CA IX and XII, exhibits hypoxic selectivity, suppressing the growth of MCF7 cells at 12.9 µM, and causes partial inhibition of hypoxia-induced CA IX expression in A431 skin cancer cells. 4e and 4f reverse chemoresistance to doxorubicin of K562/4 with overexpression of P-gp.

Design, Synthesis and Biological Assessment of Rhodanine-Linked Benzenesulfonamide Derivatives as Selective and Potent Human Carbonic Anhydrase Inhibitors.

A novel series of twenty-five rhodamine-linked benzenesulfonamide derivatives (7a-u and 9a-d) were synthesized and screened for their inhibitory action against four physiologically relevant human (h) carbonic anhydrase (CA) isoforms, namely hCA I, hCA II, hCA IX, and hCA XII. All the synthesized molecules showed good to excellent inhibition against all the tested isoforms in the nanomolar range due to the presence of the sulfonamide as a zinc binding group. The target compounds were developed from indol-3-ylchalcone-linked benzenesulfonamide where the indol-3-ylchalcone moiety was replaced with rhodanine-linked aldehydes or isatins to improve the inhibition. Interestingly, the molecules were slightly more selective towards hCA IX and XII compared to hCA I and II. The most potent and efficient ones against hCA I were 7h (KI 22.4 nM) and 9d (KI 35.8 nM) compared to the standard drug AAZ (KI 250.0 nM), whereas in case of hCA II inhibition, the derivatives containing the isatin nucleus as a tail were preferred. Collectively, all compounds were endowed with better inhibition against hCA IX compared to AAZ (KI 25.8 nM) as well as strong potency against hCA XII. Finally, these newly synthesized molecules could be taken as potential leads for the development of isoform selective hCA IX and XII inhibitors.

3H-1,2-Benzoxaphosphepine 2-oxides as selective inhibitors of carbonic anhydrase IX and XII

The synthesis of 3H-1,2-benzoxaphosphepine 2-oxides and evaluation of their inhibitory activity against human carbonic anhydrase (hCA) isoforms I, II, IX, and XII are described. The target compounds were obtained via a concise synthesis from commercial salicylaldehydes and displayed low to sub-micromolar inhibition levels against the tumour-associated isoforms hCA IX and XII. All obtained benzoxaphosphepine 2-oxides possess remarkable selectivity for inhibition of hCA IX/XII over the off-target cytosolic hCA isoforms I and II, whose inhibition may lead to side effects.

Novel benzenesulfonamide-thiouracil conjugates with a flexible N-ethyl acetamide linker as selective CA IX and CA XII inhibitors.

Novel benzenesulfonamide derivatives linked to diverse functionalized thiouracils through a flexible N-ethyl acetamide linker were designed and synthesized as carbonic anhydrase (CA) inhibitors. The synthesized candidates demonstrated a potent inhibitory activity against four different CA isoforms in the nanomolar range. Compound 10d showed more than twofold higher potency than the reference AAZ against CA II with Ki of 5.65 and 12 nM, respectively. Moreover, compounds 10d and 20 revealed potent activity against CA IX with Ki of 18.1 and 14.2 nM, respectively. In addition, 10c, 10d, 11b, 11c, and 20 demonstrated high potency against the CA XII isozyme with a Ki range of 4.18-4.8 nM. Most of the synthesized derivatives displayed preferential selectivity towardthe CA IX and CA XII isoforms over CA I and CA II. Compounds 11a and 20 exhibited favorable selectivity toward CA IX over CA II with a selectivity index (SI) of 14.36 and 16.62, respectively, and toward CA XII over CA II with SI of 71.01 and 51.19, respectively. Molecular docking simulations showed that the synthesized conjugates adopted comparable binding modes in the CA I, CA II, CA IX, and CA XII isoforms, involving the deep fitting of the sulfonamide moiety in the base of the CA active site via chelation of the Zn2+ ion and H-bond interaction with the key amino acids Thr199 and/or Thr200. Moreover, the N-ethyl acetamide flexible linker enables the substituted thiouracils and fused thiouracil tail to achieve multiple interactions with the surrounding hydrophobic and hydrophilic regions.

1,2,3-Benzoxathiazine-2,2-dioxides – effective inhibitors of human carbonic anhydrases

A series of 1,2,3-benzoxathiazine-2,2-dioxides possessing various substituents in the 5, 7, or 8 position was obtained from corresponding 2-hydroxybenzaldehydes in their reaction with sulfamoyl chloride. 5-, 7-, and 8-aryl substituted 1,2,3-benzoxathiazine-2,2-dioxides were prepared from aryl substituted 2-hydroxybenzaldehydes obtained from 3-, 4-, or 6-bromo-2-hydroxybenzaldehydes via two-step protocol. 1,2,3-Benzoxathiazine-2,2-dioxides were investigated for the inhibition of four human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms, cytosolic hCA I and II and tumour-associated transmembrane hCA IX and XII. Twenty four derivatives of 1,2,3-benzoxathiazine 2,2-dioxide were obtained. Most of them act as nanomolar inhibitors of hCA IX and XII. Almost all compounds except 2d and 5a-e also express nanomolar inhibitory activity for hCA II. hCA I is poorly inhibited or not inhibited by 1,2,3-benzoxathiazine 2,2-dioxides. Some of the new derivatives exhibit promising selectivity towards CA IX/XII over hCA I, although none of the compounds are selective towards CA IX/XII over both hCA I and II.

Tail approach synthesis of triazolylthiazolotriazole bearing benzenesulfonamides as carbonic anhydrase inhibitors capable of inducing apoptosis.

Inhibition of human carbonic anhydrase (hCA) isoform IX with concurrent induction of apoptosis is a promising approach for targeting cancer in humans. Prompted by the scope, novel benzenesulfonamides containing the 1,2,3-triazolylthiazolotriazole tail were synthesized and screened as inhibitors of hCA isoforms I, II, IV, and IX. The tumor-associated isoform hCA IX was strongly inhibited by the sulfonamides reported here with KI values ranging from 45 nM to 1.882 μM. Overall, nine compounds showed hCA IX inhibition with KI < 250 nM. The glaucoma-associated isoform hCA II was moderately inhibited while the cytosolic isoform hCA I and membrane-bound isoform hCA IV were weakly inhibited by the synthesized sulfonamides. Compound 6Ac (KI = 3.6 nM) was found to be an almost three times more potent inhibitor of hCA II as compared to the standard drug acetazolamide (KI = 12.1 nM). The selective hCA IX inhibitors were further studied for their apoptotic efficacy in goat ovarian cells and showed better results as compared to the control. A comparative study of previously synthesized compounds and molecular docking study of representative compounds revealed some important generalizations that could prove beneficial in further investigations of isoform-selective hCA inhibitors.

Benzenesulfonamides with trisubstituted triazole motif as selective carbonic anhydrase I, II, IV, and IX inhibitors.

Twenty novel 1,2,3-triazole benzenesulfonamides featuring nitrile 8a-g, carbothioamide 9a-f, and N'-hydroxycarboximidamide 10a-g functionalities were designed and synthesized to improve potency and selectivity as carbonic anhydrase inhibitors (CAIs). The synthesized 1,2,3-triazole compounds were tested in vitro as CAIs against four physiologically and pharmacologically relevant isoforms of human carbonic anhydrase (hCA I, II, IV, and IX). Compounds 8a-g, 9a-f, and 10a-g displayed variable inhibition constants ranging from 8.1 nM to 3.22 μM for hCA I, 4.7 nM to 0.50 μM for hCA II, 15.0 nM to 3.7 μM for hCA IV, and 29.6 nM to 0.27 μM for hCA IX. As per the inhibition data profile, compounds 9a-e exhibited strong efficacy for hCA IV, whereas the inhibition was found to be somewhat diminished in the case of hCA IX by nearly all the compounds. A computational protocol based on docking and MM-GBSA was conducted to reveal the plausible interactions of the targeted sulfonamides within the hCA II and IX binding sites. The outcomes of appending various functionalities at the C-4 position of the 1,2,3-triazole motif over the inhibition potential and selectivity of the designed sulfonamides were examined with a potential for the discovery of new isoform selective CAIs. The CAI and SAR data established the significance of the synthesized 1,2,3-triazoles as building blocks for developing CAI drugs.