Boron-containing carbonic anhydrases inhibitors.

Over the last decades, the medicinal chemistry of boron-based compounds has been extensively explored, designing valuable small molecule drugs to tackle diseases and conditions, such as cancer, infections, inflammatory and neurological disorders. Notably, boron has proven to also be a valuable element for the development of inhibitors of the metalloenzymes carbonic anhydrases (CAs), a class of drug targets with significant potential in medicinal chemistry. Incorporating boron into carbonic anhydrase inhibitors (CAIs) can modulate the ligand ability to recognize the target and/or influence selectivity towards different CA isoforms, using the tail approach and boron-based tails. The electron-deficient nature of boron and its associated properties have also led to the discovery of novel zinc-binding CAIs, such as boronic acids and the benzoxaboroles, capable of inhibiting the CAs upon a Lewis acid-base mechanism of action. The present manuscript reviews the state-of-the-art of boron-based CAIs. As research in the applications of boron compounds in medicinal chemistry continues, it is anticipated that new boron-based CAIs will soon expand the current array of such compounds. However, further research is imperative to fully unlock the potential of boron-based CAIs and to advance them towards clinical applications.

Identification of thienopyrimidine derivatives tethered with sulfonamide and other moieties as carbonic anhydrase inhibitors: Design, synthesis and anti-proliferative activity.

Eighteen novel compounds harboring the privileged thienopyrimidine scaffold (5a-q, and 6a),were designed based on molecular hybridization strategy. These compounds were synthesized and tested for their inhibitory activity against four different carbonic anhydrase isoforms: CA I, II, IX, and XII. Microwave and conventional techniques were applied for their synthesis. Compounds 5b, 5g, 5l, and 5p showed the highest inhibition activity against the four CA isoforms. Compound 5p exhibited promising inhibitory activity against CA II, CA IX and CA XII with KI values of8.6, 13.8, and 19 nM, respectively, relative to AAZ, where KIs = 12, 25, and 5.7 nM, respectively. Also, compound 5 l showed significant activity against the tumor-associated isoform CA IX with KI = 16.1 nM. All the newly synthesized compounds were also screened for their anticancer activity against NCI 60 cancer cell lines at a 10 µM concentration. Compound 5n showed 80.38, 83.95, and 87.39 % growth inhibition against the leukemic cell lines CCRF-CEM, HL-60 (TB), and RPMI-8226, respectively. Also, 5 h showed 87.57 % growth inhibition against breast cancer cell line MDA-MB-468; and 66.58 and 60.95 % inhibitionagainst renal cancer cell lines UO-31, and ACHN, respectively. A molecular docking studywas carried out to predict binding modes of our synthesized compounds in the binding pockets of the four carbonic anhydrase isoforms, and results revealed that compounds 5b, 5g, 5l, and 5p succeeded in mimicking the binding mode of AAZ through metal coordination with Zn+2 ion and binding to the amino acids Thr199, His94, and His96 that are critical for activity.

Mitigating the resistance of MCF-7 cancer cells to Doxorubicin under hypoxic conditions with novel coumarin based carbonic anhydrase IX and XII inhibitors.

In the present study, the design and synthesis of novel coumarin derivatives 8a-h, 11a-d and 16a-c as potential selective inhibitors for the tumor associated human carbonic anhydrase isoforms (hCA IX and XII) was reported. All the newly synthesized derivatives showed potent to mild activity against the targeted CA IX (KI = 0.08-9.57 µM), with selectivity indices over CA I (SI = 2.0-21.9) and over CA II (SI = 1.1-15.7). They showed similar activities against CA XII (KI = 0.06-9.48 µM) with selectivity indices over CA I (SI = 1.4-21.2) and CA II (SI = 0.9-15.5). Compound 16b featuring sulfonamide function possessed promising inhibitory activities against the targeted isoforms CA IX and XII with KI values of 0.08 and 0.06 µM, respectively. Interestingly, it was found that using compound 16b at a nontoxic concentration as an adjuvant with Doxorubicin against MCF-7 cells enhanced the cytotoxicity under hypoxia by almost 3.5 folds; IC50 decreased from 25.74 to 7.43 µM. Therefore, compound 16b restored the cytotoxicity of Doxorubicin against MCF-7 cells under hypoxia, almost as normoxia. Furthermore, flow cytometry analysis of a combination treatment of compound 16b and Doxorubicin to the MCF7 cell line revealed an increase in cell cycle arrest at the G2/M phase and a more efficient apoptotic effect than Doxorubicin alone. Furthermore, compound 16b showed no cytotoxicity against normal breast MCF-10A cell line (IC50 = 296.25 µM).

Cloning, expression, and purification of an α-carbonic anhydrase from Toxoplasma gondii to unveil its kinetic parameters and anion inhibition profile.

Toxoplasmosis, induced by the intracellular parasite Toxoplasma gondii, holds considerable implications for global health. While treatment options primarily focusing on folate pathway enzymes have notable limitations, current research endeavours concentrate on pinpointing specific metabolic pathways vital for parasite survival. Carbonic anhydrases (CAs, EC 4.2.1.1) have emerged as potential drug targets due to their role in fundamental reactions critical for various protozoan metabolic processes. Within T. gondii, the Carbonic Anhydrase-Related Protein (TgCA_RP) plays a pivotal role in rhoptry biogenesis. Notably, α-CA (TcCA) from another protozoan, Trypanosoma cruzi, exhibited considerable susceptibility to classical CA inhibitors (CAIs) such as anions, sulphonamides, thiols, and hydroxamates. Here, the recombinant DNA technology was employed to synthesise and clone the identified gene in the T. gondii genome, which encodes an α-CA protein (Tg_CA), with the purpose of heterologously overexpressing its corresponding protein. Tg_CA kinetic constants were determined, and its inhibition patterns explored with inorganic metal-complexing compounds, which are relevant for rational compound design. The significance of this study lies in the potential development of innovative therapeutic strategies that disrupt the vital metabolic pathways crucial for T. gondii survival and virulence. This research may lead to the development of targeted treatments, offering new approaches to manage toxoplasmosis.

A comprehensive investigation of the anion inhibition profile of a ß-carbonic anhydrase from Acinetobacter baumannii for crafting innovative antimicrobial treatments.

This study refers to the intricate world of Acinetobacter baumannii, a resilient pathogenic bacterium notorious for its propensity at antibiotic resistance in nosocomial infections. Expanding upon previous findings that emphasised the bifunctional enzyme PaaY, revealing unexpected γ-carbonic anhydrase (CA) activity, our research focuses on a different class of CA identified within the A. baumannii genome, the ß-CA, designated as 𝛽-AbauCA (also indicated as CanB), which plays a crucial role in the resistance mechanism mediated by AmpC beta-lactamase. Here, we cloned, expressed, and purified the recombinant 𝛽-AbauCA, unveiling its distinctive kinetic properties and inhibition profile with inorganic anions (classical CA inhibitors). The exploration of 𝛽-AbauCA not only enhances our understanding of the CA repertoire of A. baumannii but also establishes a foundation for targeted therapeutic interventions against this resilient pathogen, promising advancements in combating its adaptability and antibiotic resistance.

Novel thiazolotriazole and triazolothiadiazine scaffolds as selective tumor associated carbonic anhydrase inhibitors endowed with cathepsin B inhibition.

The present research focused on the tail-approach synthesis of novel extended thiazolotriazoles (8a-8j) and triazolothiadiazines (11a-11j) including aminotriazole intermediate 10. After successful synthesis, all the compounds were evaluated for their inhibition potential against cytosolic isoforms of human carbonic anhydrase (hCA I, II), tumor-linked transmembrane isoforms (hCA IX, XII), and cathepsin B. As per the inhibition data, the newly synthesized compounds showed poor inhibition against hCA I. Many of the compounds showed effective inhibition toward hCA IX and/or XII in low nanomolar concentration. Despite the strong to moderate inhibition of hCA II by these compounds, more than half of them demonstrated better inhibition against hCA IX and/or XII, comparatively. Further, insights of CA inhibition data of these extended analogs and their comparison with earlier reported thiazolotriazole and triazolothiadiazine derivatives might help in the rational design of novel potent and selective hCA IX and XII inhibitors. The novel compounds were also found to possess anti-cathepsin B potential at a low concentration of 10-7 M. Broadly, compounds of series 11a-11j presented more effective inhibition against cathepsin B than their counterparts in series 8a-8j. Moreover, these in vitro results with respect to cathepsin B inhibition were also supported by the in silico insights obtained via molecular modeling studies.

In-vitro and in-silico investigations of SLC-0111 hydrazinyl analogs as human carbonic anhydrase I, II, IX, and XII inhibitors.

Two novel series of hydrazinyl-based benzenesulfonamides 9a-j and 10a-j were designed and synthesized using SLC-0111 as the lead molecule. The newly synthesized compounds were evaluated for their inhibitory activity against four different human carbonic anhydrase (hCA) isoforms I, II, IX, and XII. Both the series reported here were practically inactive against the off-target isozyme hCA I. Notably, derivative 10a exhibited superior potency (Ki of 10.2 nM) than acetazolamide (AAZ) against the cytosolic isoform hCA II. The hCA IX and XII isoforms implicated in tumor progression were effectively inhibited with Kis in the low nanomolar range of 20.5-176.6 nM and 6.0-127.5 nM, respectively. Compound 9g emerged as the most potent and selective hCA IX and XII inhibitor with Ki of 20.5 nM and SI of 200.1, and Ki of 6.0 nM and SI of 683.7, respectively, over hCA I. Furthermore, six compounds (9a, 9h, 10a, 10g, 10i, and 10j) exhibited significant inhibition toward hCA IX (Kis = 27.0, 41.1, 27.4, 25.9, 40.7, and 30.8 nM) relative to AAZ and SLC-0111 (Kis = 25.0 and 45.0 nM, respectively). These findings underscore the potential of these derivatives as potent and selective inhibitors of hCA IX and XII over the off-target hCA I and II.

Chalcone-based benzenesulfonamides as potent and selective inhibitors for human carbonic anhydrase II: Design, synthesis, in vitro, and in silico studies.

Sulfonamides are promising classical carbonic anhydrase (CA; EC 4.2.1.1) inhibitors, being used for several medical purposes such as diuretics, anticonvulsants, topically acting antiglaucoma agents, for antiobesity and anticancer therapies. Herein, a series of chalcone-based benzenesulfonamides (3a‒m) was synthesized and assessed for its inhibitory activity against a panel of four human carbonic anhydrases (hCA isoforms I, II, IX, and XII). Most compounds displayed single- to double-digit nanomolar inhibition constants (Kis), with some derivatives being more potent and/or selective than the standard drug acetazolamide (AAZ). Among the synthesized compounds, 3g compound demonstrated the highest inhibitory activity against the hCA II isoform (Ki = 2.5 nM) with 30-, 9-, and 11-fold selectivity for hCA II over the I, IX, and XII isoforms, respectively. Structure-activity relationships for different substitution patterns were analyzed. Additionally, a molecular docking study showed that compound 3g bound to hCA II by coordinating with the zinc ion through the deprotonated benzenesulfonamide moiety, in addition to a hydrogen bond formed between an oxygen of the sulfonamide moiety and Thr199. Moreover, the chalcone core participated in van der Waals interactions with some active site residues, such as Ile91, Val121, and Leu198. Consequently, this report introduces a successful approach toward identifying compound 3g as a highly potent and selective chalcone-based benzenesulfonamide inhibitor of hCA II worthy of further investigation.

Benzenesulfonamides functionalized with triazolyl-linked pyrazoles possess dual cathepsin B and carbonic anhydrase inhibitory action.

The design and synthesis of a library of 21 novel benzenesulfonamide-bearing 3-functionalized pyrazole-linked 1,2,3-triazole derivatives as dual inhibitors of cathepsin B and carbonic anhydrase enzymes are reported. The target 1,2,3-triazole-linked pyrazolic esters (16) were synthesized by the condensation of 1,2,3-triazolic diketo esters with 4-hydrazinobenzenesulfonamide hydrochloride, and these were further converted into the corresponding carboxylic acid (17) and carboxamide (18) analogs. The synthesized compounds were assayed in vitro for their inhibition potential against human carbonic anhydrase (hCA) isoforms I, II, IX, and XII. They were found to be potent inhibitors at the low nanomolar level against the cancer-related hCA IX and XII and to be selective towards the cytosolic isoform hCA I. The physiologically important isoform hCA II was potently inhibited by all the newly synthesized compounds showing KI values ranging between 0.8 and 561.5 nM. The ester derivative 16c having 4-fluorophenyl (KI = 5.2 nM) was the most potent inhibitor of hCA IX, and carboxamide derivative 18b (KI = 2.2 nM) having 4-methyl substituted phenyl was the most potent inhibitor of hCA XII. The newly synthesized compounds exhibited potent cathepsin B inhibition at 10-7 M concentration. In general, the carboxamide derivatives (18) showed higher % inhibition as compared with the corresponding ester derivatives (16) and carboxylic acid derivatives (17) for cathepsin B. The interactions of the target compounds with the active sites of cathepsin B and CA were studied through molecular docking studies. Further, the in silico absorption, distribution, metabolism, excretion, and toxicity (ADMET) and drug-likeness properties of the target compounds were also studied.

1,2,3-Triazole-based esters and carboxylic acids as nonclassical carbonic anhydrase inhibitors capable of cathepsin B inhibition.

Herein, we report the design and synthesis of a library of 28 new 1,2,3-triazole derivatives bearing carboxylic acid and ester moieties as dual inhibitors of carbonic anhydrase (CA) and cathepsin B enzymes. The synthesised compounds were assayed in vitro for their inhibition potential against four human CA (hCA) isoforms, I, II, IX and XII. The carboxylic acid derivatives displayed low micromolar inhibition against hCA II, IX and XII in contrast to the ester derivatives. Most of the target compounds showed poor inhibition against the hCA I isoform. 4-Fluorophenyl appended carboxylic acid derivative 6c was found to be the most potent inhibitor of hCA IX and hCA XII with a KI value of 0.7 µM for both the isoforms. The newly synthesised compounds showed dual inhibition towards CA as well as cathepsin B. The ester derivatives exhibited higher % inhibition at 10-7 M concentration as compared with the corresponding carboxylic acid derivatives against cathepsin B. The results from in silico studies of the target compounds with the active site of cathepsin B were found in good correlation with the in vitro results. Moreover, two compounds, 5i and 6c, showed cytotoxic activity against A549 lung cancer cells, with IC50 values lower than 100 µM.

Repurposing antiparasitic N,N'-aliphatic diamine derivatives as promising antimycobacterial agents.

In previous studies, we demonstrated the potent activity of a library of 25 N,N'-disubstituted diamines (NNDDA) toward Trypanosomatid and Apicomplexa parasites. Considering the structure similarity between this collection and SQ109, an antituberculosis compound, and its compelling antiparasitic properties, we aimed to repurpose this library for tuberculosis treatment. We assayed this collection against Mycobacterium tuberculosis H37Rv and M. avium, obtaining several compounds with MIC values below 10 µM. The most active analogs were also evaluated against M. smegmatis, a non-pathogenic species, and the non-tuberculosis mycobacteria M. abscessus, M. kansasii, and M. fortuitum. 3c stands out as the lead mycobacterial compound of the collection, with potent activity against M. tuberculosis (minimal inhibitory concentration [MIC] = 3.4 µM) and moderate activity against M. smegmatis, M. kansasii, and M. fortuitum (all with MIC values of 26.8 µM). To unravel the mechanism of action, we employed the web-based platform Polypharmacology Browser 2 (PPB2), obtaining carbonic anhydrases as potential drug targets. Nevertheless, none of the compounds displayed experimental inhibition. In summary, our study confirms the validity of the repurposing approach and underscores the antimycobacterial potential of NNDDA compounds, especially the analog 3c, setting a stepping stone for further studies.

Potent and selective carbonic anhydrase inhibition activities of pyrazolones bearing benzenesulfonamides.

This research introduces a series of fourteen 4-aryl-hydrazonopyrazolone sulfonamide derivatives, denoted as 3(a-g) and 4(a-g), which encompass various aromatic substitutions. The aim was to assess the inhibitory potential of these compounds against four significant isoforms, including the cytosolic isoforms hCA I and II, as well as the tumor-associated membrane-bound isoforms hCA IX and XII. Most of the tested compounds exhibited substantial inhibition against the tumor-associated isoform hCA IX, with Ki values spanning from 1.1 to 158.2 nM. Notably, compounds 3e and 3g showed particularly strong inhibitory activity against the tumor-associated membrane-bound isoforms, hCA IX and XII, while maintaining a high selectivity ratio over cytosolic off-target isoforms hCA I and II. This selectivity is vital due to the potential of hCA IX and hCA XII as drug targets for hypoxic tumors. In an effort to create novel analogs that exhibit enhanced carbonic anhydrase inhibitory activity and specificity, we investigated the structure-activity relationships of these compounds and provided a concise interpretation of our findings. Consequently, these compounds merit consideration for subsequent medicinal and pharmacological research, holding potential for developing novel therapeutic agents targeting specific isoforms in hypoxic tumors.

Design and synthesis of sulfonamides incorporating a biotin moiety: Carbonic anhydrase inhibitory effects, antiproliferative activity and molecular modeling studies.

Sulfonamides constitute an important class of classical carbonic anhydrase (CA, EC 4.2.1.1) inhibitors. Herein we have accomplished the conjugation of biotin with an ample number of sulfonamide motifs with the aim of testing them in vitro as inhibitors of the human carbonic anhydrase (hCA) isoforms I and II (cytosolic isozymes), as well as hCA IX and XII (transmembrane, tumor-associated enzymes). Most of these newly synthesized compounds exhibited interesting inhibition profiles, with activities in the nanomolar range. The presence of a 4-F-C6H4 moiety, also found in SLC-0111, afforded an excellent selectivity towards the tumor-associated hypoxia-induced hCA isoform XII with an inhibition constant (KI) of 4.5 nM. The 2-naphthyl derivative was the most potent inhibitor against hCA IX (KI = 6.2 nM), 4-fold stronger than AAZ (KI = 25 nM) with very good selectivity. Some compounds were chosen for antiproliferative activity testing against a panel of 3 human tumor cell lines, one compound showing anti-proliferative activity on glioblastoma, triple-negative breast cancer, and pancreatic carcinoma cell lines.

Discovery of the first-in-class potent and isoform-selective human carbonic anhydrase III inhibitors.

Considering the unrecognised physio-pathological role of human carbonic anhydrase III (hCA III), a structure-based drug design was set up to identify the first-in-class potent and selective inhibitors of this neglected isoform. hCA III targeting was planned considering a unique feature of its active site among the other hCA isoforms, i.e. the Leu198/Phe198 substitution which interferes with the binding of aromatic/heterocyclic sulfonamides and other inhibitors. Thus, new aliphatic primary sulfonamides possessing long and flexible (CH2)nSO2NH2 moieties were designed to coordinate the zinc(II) ion, bypassing the bulky Phe198 residue. They incorporate 1,2,3-triazole linkers which connect the tail moieties to the sulfonamide head, enhancing thus the contacts at the active site entrance. Some of these compounds act as nanomolar and selective inhibitors of hCA III over other isoforms. Docking/molecular dynamics simulations were used to investigate ligand/target interactions for these sulfonamides which might improve our understanding of the physio-pathological roles of hCA III.

Inhibition studies with simple and complex (in)organic anions of the γ-carbonic anhydrase from Mammaliicoccus (Staphylococcus) sciuri, MscCAγ.

The γ-carbonic anhydrase (CA, EC 4.2.1.1) from the pathogenic bacterium, Mammaliicoccus (Staphylococcus) sciuri (MscCAγ) was recently cloned and purified by our groups. Here we investigated inhibition of this enzyme with (in)organic simple and complex anions, in the search of inhibitors with potential applications. The most effective inhibitors (KIs in the micromolar range) were peroxydisulfate and trithiocarbonate, whereas submillimolar inhibition was observed with N,N-diethyldithiocarbamate and phenylboronic acid (KIs of 0.5-0.9 mM). Thiocyanate, hydrogensulfide, bisulphite, stannate, divanadate, tetraborate, perrhenate, perruthenate, hexafluorophosphate, triflate and iminodisulfonate showed KIs of 1.0-13.7 mM. Cyanate, cyanide, azide, carbonate, nitrate, tellurate, selenocyanide, tetrafluoroborate, sulfamide, sulphamic acid and phenylarsonic acid were weaker inhibitors, with KIs in the range of 25.2-95.5 mM, whereas halides, bicarbonate, nitrite, sulphate, perchlorate and fluorosulfonate did not show inhibitory action up until 100 mM concentrations in the assay system. Finding more effective MscCAγ inhibitors may be helpful to fight drug resistance to antibiotics.

Inhibition of pathogenic bacterial carbonic anhydrases by monothiocarbamates.

Carbonic anhydrases (CAs) from the pathogenic bacteria Nesseria gonorrhoeae and vancomycin-resistant enterococci (VRE) have recently been validated as antibacterial drug targets. Here we explored the inhibition of the α-CA from N. gonorrhoeae (α-NgCA), of α- and γ-class enzymes from Enterococcus faecium (α-EfCA and γ-EfCA) with a panel of aliphatic, heterocyclic and aryl-alkyl primary/secondary monothiocarbamates (MTCs). α-NgCA was inhibited in vitro with KIs ranging from 0.367 to 0.919 µM. The compounds inhibited the α-EfCA and γ-EfCA with KI ranges of 0.195-0.959 µM and of 0.149-1.90 µM, respectively. Some MTCs were also investigated for their inhibitory effects on the growth of clinically-relevant N. gonorrhoeae and VRE strains. No inhibitory effects on the growth of VRE were noted for all MTCs, whereas one compound (13) inhibited the growth N. gonorrhoeae strains at concentrations ranging from 16 to 64 µg/mL. This suggests that compound 13 may be a potential antibacterial agent against N. gonorrhoeae.

Potent inhibitors of tumor associated carbonic anhydrases endowed with cathepsin B inhibition.

Twenty-one novel extended analogs of acetazolamide were synthesized and screened in vitro for their inhibition efficacy against human carbonic anhydrase (hCA) isoforms I, II, IX, XII, and cathepsin B. The majority of the compounds were found to be effective inhibitors of tumor-associated hCA IX and XII, and poor inhibitors of cytosolic hCA I. Despite the strong to moderate inhibition potential possessed by these compounds toward another cytosolic isoform hCA II, some of them demonstrated better potency against hCA IX and/or XII isoforms as compared to hCA II. Four compounds (11f, 11g, 12c, and 12g) effectively inhibited hCA IX and/or XII isoforms with considerable selectivity over the off-targets hCA I and II. Interestingly, five compounds, including 11f, 11g, 12c, 12d, and 12g, inhibited hCA IX even better than the clinically used acetazolamide. Some of the novel synthesized compounds exhibited higher anti-cathepsin B potential than acetazolamide, with % inhibition of around 50%, at a concentration of 10-7 M. Further, two compounds (12g and 12c) that showed effective and selective inhibition activity profiles against hCA IX and XII were additionally found to be effective inhibitors of cathepsin B.

Conformationally Restricted Glycoconjugates Derived from Arylsulfonamides and Coumarins: New Families of Tumour-Associated Carbonic Anhydrase Inhibitors.

The involvement of carbonic anhydrases (CAs) in a myriad of biological events makes the development of new inhibitors of these metalloenzymes a hot topic in current Medicinal Chemistry. In particular, CA IX and XII are membrane-bound enzymes, responsible for tumour survival and chemoresistance. Herein, a bicyclic carbohydrate-based hydrophilic tail (imidazolidine-2-thione) has been appended to a CA-targeting pharmacophore (arylsulfonamide, coumarin) with the aim of studying the influence of the conformational restriction of the tail on the CA inhibition. For this purpose, the coupling of sulfonamido- or coumarin-based isothiocyanates with reducing 2-aminosugars, followed by the sequential acid-promoted intramolecular cyclization of the corresponding thiourea and dehydration reactions, afforded the corresponding bicyclic imidazoline-2-thiones in good overall yield. The effects of the carbohydrate configuration, the position of the sulfonamido motif on the aryl fragment, and the tether length and substitution pattern on the coumarin were analysed in the in vitro inhibition of human CAs. Regarding sulfonamido-based inhibitors, the best template turned out to be a d-galacto-configured carbohydrate residue, meta-substitution on the aryl moiety (9b), with Ki against CA XII within the low nM range (5.1 nM), and remarkable selectivity indexes (1531 for CA I and 181.9 for CA II); this provided an enhanced profile in terms of potency and selectivity compared to more flexible linear thioureas 1-4 and the drug acetazolamide (AAZ), used herein as a reference compound. For coumarins, the strongest activities were found for substituents devoid of steric hindrance (Me, Cl), and short linkages; derivatives 24h and 24a were found to be the most potent inhibitors against CA IX and XII, respectively (Ki = 6.8, 10.1 nM), and also endowed with outstanding selectivity (Ki > 100 µM against CA I, II, as off-target enzymes). Docking simulations were conducted on 9b and 24h to gain more insight into the key inhibitor-enzyme interactions.

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 KI-s in the subnanomolar range and good selectivity indexes for inhibiting the target versus the off-target isoforms.

Coumarins inhibit η-class carbonic anhydrase from Plasmodium falciparum.

Coumarins were discovered to act as inhibitors of α-carbonic anhydrases (CAs, EC 4.2.1.1) after undergoing hydrolysis mediated by the esterase activity of the enzyme to the corresponding 2-hydroxycinnamic acids. Other classes of CAs among the eight currently known do not possess esterase activity or this activity was poorly investigated. Hence, we decided to look at the potential of coumarins as inhibitors of the η-CA from the malaria-producing protozoan Plasmodium falciparum, PfaCA. A panel of simple coumarins incorporating hydroxyl, amino, ketone or carboxylic acid ester moieties in various positions of the ring system acted as low to medium micromolar PfaCA inhibitors, whereas their affinities for the cytosolic off-target human isoforms hCA I and II were in a much higher range. Thus, we confirm that η-CAs possess esterase activity and that coumarins effectively inhibit this enzyme. Elaboration of the simple coumarin scaffolds investigated here may probably lead to more effective PfaCA inhibitors.