Search

Pyrazole-based carbohydrazone hybrids have been considered to be a remarkable class of compounds in pharmaceutical chemistry. Here, we reported bioactivities of 4-(3-(2-(arylidene)hydrazin-1-carbonyl)-5-phenyl-1H-pyrazol-1-yl)benzenesulfonamides (1-27) towards CA isoenzymes (hCA I, hCA II, hCA IX) and human oral squamous cell carcinoma cell line. Compounds 19 (Ki = 10.1 nM, hCA I/hCA IX = 749.6), 22 (Ki = 18.5 nM, hCA I/hCA IX = 429.2), 26 (Ki = 14.5 nM, hCA I/hCA IX = 596.9), 27 (Ki = 21.5 nM, hCA I/hCA IX = 413.1) were more potent and selective inhibitors of cancer-associated hCA IX isoenzyme. Compounds 22 and 26 were also found to be approximately three times more selective hCA IX inhibitors over off-target hCA II at low nanomolar. Compounds 19, 22, 23, 24, and 26 with IC

In the presented work, we report the design and synthesis of novel SLC-0111 thiazole and thiadiazole analogues (11a–d, 12a–d, 16a–c and 17a–d). A bioisosteric replacement approach was adopted to replace the 4-fluorophenyl tail of SLC-0111 with thiazole and thiadiazole ones, which were thereafter extended with lipophilic un/substituted phenyl moieties. All the newly synthesized SLC-0111 analogues were evaluated in vitro for their inhibitory activity towards a panel of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1) isoforms (hCA I, II, IX and XII), using a stopped-flow CO2 hydrase assay. All the examined isoforms were inhibited by the primary sulfonamide derivatives (11a–d and 12a–d) in variable degrees with the following KI ranges: 162.6–7136 nM for hCA I, 9.0–833.6 nM for hCA II, 7.9–153.0 nM for hCA IX, and 9.4–94.0 nM for hCA XII. In particular, compounds 12b and 12d displayed 5.5-fold more potent inhibitory activity (KIs = 8.3 and 7.9 nM, respectively) than SLC-0111 (KI = 45 nM) towards hCA IX. Molecular docking study was carried out for 12d within the hCA IX (PDB 3IAI ) active site, to justify its inhibitory activity.

Carbonic anhydrase (CA) inhibitory activities of newly synthesized quinazoline-linked benzensulfonamides 10–29, 31, 32, 35, 36, and 45–51 against human CA (hCA) isoforms I, II, IX, and XII were measured and compared to that of acetazolamide (AAZ) as a standard inhibitor. Potent selective inhibitory activity against hCA I was exerted by compounds 14, 15, 17, 19, 20, 21, 24, 25, 28, 29, 31, 35, 45, 47, 49, and 51 with inhibition constant (KIs) values of 39.4–354.7 nM that were nearly equivalent or even greater than that of AAZ (KI, 250.0 nM). Compounds 15, 20, 24, 28, 29, 45 and 47 proved to have inhibitory activities against hCA II with (KIs, 0.73–16.5 nM) that were similar or improved to that of AAZ (KI, 12.0 nM). Compounds 13–29, 31–32, and 45–51 displayed potent hCA IX inhibitory activities (KIs, 1.6–32.2 nM) that were more effective than or nearly equal to AAZ (KI, 25.0 nM). Compounds 14, 15, 20, 21, 26, 45, and 47 exerted potent hCA XII inhibitory activities (KIs, 5.2–9.2 nM), indicating similar CAI activities as compared to that of AAZ (KI, 5.7 nM).

We describe the synthesis of a series of novel 1-aroyl/acyl-3-(3-aminosulfonylphenyl) thioureas (4a–k) acting as human carbonic anhydrase (hCA, EC 4.2.1.1) inhibitors. Reaction of alkyl/aryl isothiocyanates with 3-aminobenzenesulfonamide afforded a series of the title compounds incorporating a variety of short as well as highly lipophilic long tails. The newly synthesized sulfonamides were evaluated against 4 physiologically relevant CA isoforms (hCA I, II, IV, and IX). Several compounds showed interesting inhibitory activity. The tumor-associated hCA IX was the most sensitive isoform to inhibition with these compounds, with KIs in the range of 21.5–44.0 nM and selectivity ratios over the major cytosolic isoform hCA II in the range of 3.35–37.3. The sulfonamides incorporating the phenylacetylthioureido and pentadecanoylthioureido moieties were the most hCA IX-selective inhibitors detected in this work, making them of interest for further investigations.

Recently, different mechanisms for inhibition of carbonic anhydrases (CAs) have been reported, such as the classical zinc-binding (exerted by sulfonamides and carboxylic acids) as well as occluding the entrance of the CA active site (exerted by coumarins). In this manuscript, we studied the effect of combining the pharmacopheric parts responsible for these two mechanisms on CA inhibitory potency and selectivity through the design and synthesis of novel coumarins tethered with the zinc-binding sulfonamide (5a-f, 11a-b and 13a-b) or carboxylic acid (7a-f) groups. In addition, another set of coumarin derivatives (9a-b) with no zinc-binding group (ZBG) was designed to act as non-classical CA inhibitors. The synthesized coumarins were examined for their inhibitory activities towards four hCA isoforms I, II, IX and XII. Coumarin sulfonamides (5a-f, 11a-b and 13a-b) effectively inhibited both tumor-associated hCA IX (K

A library of iodoquinazolinones endowed with benzenesulfonamide moiety was designed and synthesized as human carbonic anhydrase (hCA) inhibitors. Compounds 4–17 showed generally poor activity against the cytosolic hCA I and hCA II isoforms. Contrarily they were more potent and showed a variable spectrum of selectivity against the tumor-specific isoforms hCA IX and hCA XII. The 4-iodophenyl derivative 12 and the 4-pyridinyl derivative 15 were the most active and selective in this series against hCA IX and hCA XII isoforms with KI of 18 and 9 nM, respectively. Compounds 12 and 15 were further screened for their cytotoxicity against MCF-7, HepG-2 and HCT-116 cancer cell lines besides WI38 and MCF-10A normal cell lines to determine their selectivity towards cancer cells. Compound 12 was selective towards HepG-2 and HCT-116 cell lines but less selective towards MCF-7. While compound 15 showed higher selectivity towards HepG-2 than HCT-116 and MCF-7 cell lines. The ability of compounds 12 and 15 to sensitize the cells against gamma irradiation's effect proved their potential radiosensitizing activity. Molecular docking analysis was carried out to discover the possible binding mode of the compounds within the active site of isoform hCA IX and XII. Compounds 12 and 15 revealed the probable fundamental interactions explaining the good activity and selectivity towards the tumor-specific isoforms.

A new series of thirty s-triazinyl-substituted aminoalkylbenzenesulfonamides, incorporating a symmetric pair of amino acid moieties, is reported, together with inhibition studies of physiologically relevant human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms. Specifically, against the cytosolic hCA I, II, transmembrane hCA IV and the tumor-associated, membrane-bound hCA IX. The compounds were prepared by nucleophilic substitution of chlorine atoms from cyanuric chloride (2,4,6-trichloro-1,3,5-triazine) using environmentally friendly water-based synthetic conditions. The products yields ranged in the interval of 43–97%. Purity of the products was verified by the HPLC-DAD-ESI-Q-TOF MS method. Identity of the products was confirmed by the same method plus NMR and IR. The products showed weak inhibition of the cytosolic, off-target isozyme hCA II, but some of them were low nanomolar (i.e. strong) inhibitors of the tumor-associated hCA IX. The series offered representatives selective towards isozymes hCA I, IV and IX. 2,2′-((6-((4-sulfamoylphenethyl)amino)-1,3,5-triazine-2,4-diyl)bis(imino))disuccinic acid demonstrated highest selectivity to the tumor-associated isoform hCA IX over off-target isozymes, with impressive KI ratio (hCA II/hCA IX) 213.9 and inhibition constant equal to acetazolamide (KI = 25.8 nM). Although the selectivities of some other products, e.g. those conjugating Leu and Glu, were a bit lower (188.7 and 84.3, respectively) their inhibition constants were similar to acetazolamide too (24.0 and 27.1, respectively). The selected most impressive results from the inhibition study were interpreted via molecular modeling experiment (docking in Glide) revealing different inter-molecular enzyme-substrate interaction of 2,2′-((6-((4-sulfamoylphenethyl)amino)-1,3,5-triazine-2,4-diyl)bis(imino))disuccinic acid within specific hCA IX and hCA II microregions. Therefore, several selected compounds from this study can be considered as highly effective and selective inhibitors of hCA IX, worthy to further (preclinical) investigation.

In this study, new dibenzensulfonamides, 7–9, having the chemical structure 4,4′-(5′-chloro-3′-methyl-5-aryl-3,4-dihydro-1′H,H-[3,4′-bipyrazole]-1′,2-diyl)dibenzenesulfonamide were synthesized in five steps to develop new anticancer drug candidates. Their chemical structures were confirmed by 1H NMR, 13C NMR and HRMS spectra. Cytotoxicities of the dibenzensulfonamides were investigated towards HCC1937, MCF7, HeLa, A549 as tumor cell lines and towards MRC5 and Vero as non-tumor cells. Carbonic anhydrase (CAs, EC 4.2.1.1) inhibitory effects of the dibenzensulfonamides 7–9 were also evaluated on the cytosolic human (h) hCA I and II and the tumor-associated hCA IX and XII isoenzymes. Results indicate that both 7 and 8 induced cleavage of poly (ADP ribose) polymerase (PARP), activation of caspases -3, -7 and -9 which are the hallmarks of apoptosis. Meanwhile both compounds induced autophagy in HCC1937 cells which is shown by enhanced expression of LC3 and decreased level of p62 protein. The compounds tested were also effectively inhibited tumor-associated hCA IX and hCA XII isoenzymes in the range of 20.7–28.1 nM and 4.5–9.3 nM, respectively.

One of the most successful approaches for designing carbonic anhydrase (CA, EC 4.2.1.1) inhibitors was denominated ‘the sugar approach’. The sugar approach consists in attaching different carbohydrates to CA inhibiting pharmacophores for modulating the physicochemical properties of these pharmacological agents. In line with this approach, in this paper, we present a new class of C-glycosides incorporating the sulfamoylphenyl moiety. These compounds have been prepared by sulfamoylation of C-glycosyl phenols, which have been synthetized by aldol reaction of glycosyl ketones with the appropriate aromatic aldehydes. The inhibition profile of the new glycomimetics was determined against four human (h) CA isozymes, comprising hCAs I and II (cytosolic, ubiquitous isozymes), hCA IV and hCA IX (tumor associated isozyme). Peracetylated and deprotected C-glycosyl sulfamates showed better inhibition selectivity compared to structurally related phenylsulfamates. In this study, deprotected compound 12 was identified as selective inhibitor of hCA IX. These results confirm that attaching carbohydrate moieties to CA sulfamoylphenyl pharmacophore improves its inhibitory activity. Fil: Riafrecha, Leonardo Ezequiel. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Bua, Silvia. Università degli Studi di Firenze; Italia Fil: Supuran, Claudiu T.. Università degli Studi di Firenze; Italia Fil: Colinas, Pedro Alfonso. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Implication of carbonic anhydrases (CAs) in many physiological functions made them attractive therapeutic targets. Herein, we report the synthesis of three series of benzenesulfonamide-based compounds (5a-e, 9a-e and 10a-e) as potential ligands to four of the human CA isoforms (hCA I, hCA II, hCA IX and hCA XII). All synthesized compounds were evaluated for their CA inhibitory activity. Most of the compounds preferentially inhibited the tumor-associated isoforms IX and XII. Series 9a-e and 10a-e showed the highest activity. Of particular interest was compound 10a which demonstrated the highest activity among all compounds with Ki of 68.3 and 21.5 nM against hCA IX and hCA XII, respectively, in addition to its highest selectivity index. To get deep insight on the interaction of compound 10a with CA, docking experiment was run to study the binding interaction with key amino acids and zinc ion in the catalytic site of the four isoforms studied.

In the presented work, we report the synthesis of a series of 4-benzylidene-2-phenyl-5(4H)-imidazolone-based benzenesulfonamides 7a-f via the Erlenmeyer–Plochl reaction. All the prepared imidazolones 7a-f were evaluated as inhibitors of human (h) carbonic anhydrases (CA, EC 4.2.1.1) cytosolic isoforms hCA I and II, as well as transmembrane tumor-associated isoforms hCA IX and XII. All the tested hCA isoforms were inhibited by the prepared imidazolones 7a-f in variable degrees with the following KIs ranges: 673.2–8169 nM for hCA I, 61.2–592.1 nM for hCA II, 23–155.4 nM for hCA XI, and 21.8–179.6 nM for hCA XII. In particular, imidazolones 7a, 7e, and 7f exhibited good selectivity towards the tumor-associated isoforms (CAs IX and XII) over the off-target cytosolic (CAs I and II) with selectivity index (SI) in the range of 6.2–19.4 and 3.3–8, respectively. Moreover, imidazolones 7a-f were screened for their anticancer activity in one dose (10−5 M) assay against a panel of 60 cancer cell lines according to US-NCI protocol. Furthermore, 7a, 7e and 7f were evaluated for their anti-proliferative activity against colorectal cancer HCT-116 and breast cancer MCF-7 cell lines. Furthermore, 7e and 7f were screened for cell cycle disturbance and apoptosis induction in HCT-116 cells. Finally, a molecular docking study was carried out to rationalize the obtained results.

Carbonic anhydrases (CA, EC 4.2.1.1) are Zinc metalloenzymes and are present throughout most living organisms. Among the catalytically active isoforms are the cytosolic CA I and II, and tumor-associated CA IX and CA XII. The carbonic anhydrase (CA) inhibitory activities of newly synthesized pyrazoline-linked benzenesulfonamides 18–33 against human CA (hCA) isoforms I, II, IX, and XII were measured and compared with that of acetazolamide (AAZ), a standard inhibitor. Potent inhibitory activity against hCA I was exerted by compounds 18–25, with inhibition constant (KI) values of 87.8–244.1 nM, which were greater than that of AAZ (KI, 250.0 nM). Compounds 19, 21, 22, 29, 30, and 32 were proven to have inhibitory activities against hCA IX with KI values (5.5–37.0 nM) that were more effective than or nearly equal to that of AAZ (KI, 25.0 nM). Compounds 20–22, and 30 exerted potent inhibitory activities (KIs, 7.1–10.1 nM) against hCA XII, in comparison with AAZ (KI, 5.7 nM).

Three series of 2-oxindole benzenesulfonamide conjugates with different linkers were prepared by the condensation reaction of isatin derivatives 1a-e with different benzenesulfonamides. They were screened for their ability to inhibit human (h) carbonic anhydrase (CA, EC 4.2.1.1) isoforms hCA I, hCA II, hCA IX and hCA XII. Many compounds revealed promising activity and selectivity toward CAI, CAII and CAIX compared to acetazolamide (AAZ) especially compounds 2b (KI = 97.6, 8.0 nM against hCA I, hCA II, respectively) and 3a (KI = 90.2, 6.5 and 21.4 nM against hCA I, hCA II and hCA IX, respectively) relative to AAZ (KI = 250, 12 and 25 nM). Additionally, compound 4a revealed the highest activity against hCA II and hCA IX with KI of 3.0 and 13.9 nM, respectively. Docking of 2b, 3a and 4a into the active site of CA I, II, IX and XII revealed binding mode comparable to AAZ confirming the inhibition results.

A series of twenty four hydroxy-trifluoromethylpyrazoline-carbonyl-1,2,3-triazoles and four hydrazones bearing benzenesulfonamide moieties was obtained by condensation of carboxyhydrazides with substituted 1,3-diketones. All the newly synthesized compounds were investigated as inhibitors of physiologically and pharmacologically relevant human (h) carbonic anhydrsae (CA, EC 4.2.1.1) cytosolic isoforms hCA I and II, as well as transmembrane tumor-assosciated isoforms hCA IX and XII. These compounds exhibited excellent CA inhibitory potency against the four CA isoenzymes as compared to clinically used reference drug acetazolamide (AAZ). Some compounds bearing bulkier group at C-5′ position of 1,2,3-triazoles ring were weaker inhibitors of hCA I. Inhibition assay against hCA II indicates, that several derivatives exhibited upto 27-fold more effective inhibitory activity compared to AAZ. Five of the assayed compounds displayed low nanomolar potency (Ki ≤ 10 nM) against hCA IX, whereas five compounds were found to be endowed with excellent inhibitory potencies (Ki ≤ 5 nM) against hCA XII. The biological activity profile presented herein will be useful for designing new leads and provide candidates for preclinical investigations.

There is an urgent need for new chemotherapic agents to treat human fungal infections due to emerging and spreading globally resistance mechanisms. Among the new targets that have been recently investigated for the development of antifungal drugs there are the metallo-enzymes Carbonic Anhydrases (CAs, EC 4.2.1.1). The inhibition of the β-CAs identified in many pathogenic fungi leads to an impairment of parasite growth and virulence, which in turn leads to a significant anti-infective effect. Based on antifungal nucleoside antibiotics, the inhibition of the β-CAs from the resistance-showing fungi Candida glabrata (CgNce103), Cryptococcus neoformans (Can2) and Malasszia globosa (MgCA) with a series of benzenesulfonamides bearing nitrogenous bases, such as uracil and adenine, is here reported. Many such compounds display low nanomolar (100 nM) inhibitory potency against Can2 and CgNce103, whereas the activity of MgCA is considerably less affected (inhibition constants in the range 138.8-5601.5 nM). The β-CAs inhibitory data were compared with those against α-class human ubiquitous isoforms. Interesting selective inhibitory activities for the target fungal CAs over hCA I and II were reported, which make nitrogenous base benzenesulfonamides interesting tools and leads for further investigations in search of new antifungal with innovative mechanisms of action.

Twenty-four novel sulfonamide derivatives incorporating dipeptide tails were synthesized by facile acylation reactions of homosulfanilamide through benzotriazole or dicyclohexyl carbodiimide (DCC) mediated coupling reactions. The carbonic anhydrase (CA, EC 4.2.1.1) inhibitory activity of the new compounds was assessed against four human (h) isoforms, hCA I, hCA II, hCA IX and hCA XII. Most of the synthesized compounds showed good in vitro carbonic anhydrase inhibitory properties, with inhibition constants in the low nanomolar range. Particularly, the new dipeptide-sulfonamide conjugates incorporating Ala, Phe and Met in the dipeptide sequence, showed the most effective inhibitory activity against to CA IX and XII.

A series of novel 1,3-diaryltriazene-substituted sulfonamides was synthesized by reaction of diazonium salt of 4-amino benzenesulfonamide with substituted aromatic amines. The obtained 1,3-diaryltriazene-substituted sulfonamides were investigated as inhibitors of four selected human carbonic anhydrase (CA, EC 4.2.1.1) isoforms (hCA I, hCA II, hCA VII and hCA IX) are involved in various diseases such as glaucoma, epilepsy, retinitis pigmentosa, cancer, obesity, etc. All these sulfonamides were found to be potent inhibitors of the cytosolic isoform hCA II with low nanomolar to sub-nanomolar Kis in the range of 0.2–21.5 nM, as well as a moderate selectivity against other cytosolic isoforms hCA I and hCA VII, and great selectivity against membrane-bound isoform hCA IX was observed. Since hCA II is an important drug target for antiglaucoma agents and diuretics, these isoform-selective inhibitors may be considered of interest as tools for the development of new candidates for these conditions.

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 I s are reaching the sub-nanomolar range, 0.41–37.8 nM) and against the tumor-associated isoform hCA IX (K I s 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.

A series of novel N,N''-diaryl cyanoguanidines were synthesized by reacting diphenyl N-cyanocarbonimidate with sulfanilamide followed by treatment of the obtained cyano-O-phenylisourea with substituted aromatic amines. The newly prepared N,N''-diaryl cyanoguanidines showed a very interesting inhibition profile against four selected human carbonic anhydrase (CA, EC 4.2.1.1) isoforms, hCA I and hCA II (cytosolic), hCA IV (membrane-bound), and hCA IX (transmembrane). All these compounds showed a potent inhibition against isoform hCA II,with inhibition constants in the low nanomolar range, as well as a high selectivity for hCA II over hCA I, IV and IX. Since hCA II is an important drug target for antiglaucoma agents, these isoform-selective inhibitors may be considered of interest for further medicinal/pharmacologic studies.

Herein, we report the synthesis, characterization, and carbonic anhydrase (CA) inhibition of the newly synthesized Schiff’s bases 4–18 with benzenesulfonamide, methanesulfonamide, and methylsulfonylbenzene scaffolds. The compound inhibition profiles against human CA (hCA) isoforms I, II, IX, and XII were compared to those of the standard inhibitors, acetazolamide (AAZ) and SLC-0111 (a CA inhibitor in Phase II clinical trials for the treatment of hypoxic tumors). The hCA I was inhibited by compounds 4a–8a with inhibition constants (KI) in the range 93.5–428.1 nM (AAZ and SLC-0111: KI, 250.0 and 5080.0 nM, respectively). Compounds 4a–8a proved to be effective hCA II inhibitors, with KI ranging from 18.2 to 133.3 nM (AAZ and SLC-0111: KI, 12.0 and 960.0 nM, respectively). Compounds 4a–8a effectively inhibited hCA IX, with KI in the range 8.5–24.9 nM; these values are superior or equivalent to that of AAZ and SLC-0111 (KI, 25.0 and 45.0 nM, respectively). Compounds 4a–8a displayed effective hCA XII inhibitory activity with KI values ranging from 8.6 to 43.2 nM (AAZ and SLC-0111: KI, 5.7 and 4.5 nM, respectively). However, compounds 9b–13b and 14c–18c were found to be micromolar CA inhibitors. For molecular docking studies, compounds 5a, 6a, and 8a were selected.

Inhibition of carbonic anhydrases (CAs, EC 4.2.1.1) has clinical importance for the treatment of several diseases. They participate in crucial regulatory mechanisms for balancing intracellular and extracellular pH of the cells. Among CA isoforms, selective inhibition of hCA IX has been linked to decreasing of cell growth for both primary tumors and metastases. The discovery of novel CA inhibitors as anticancer drug candidates is a current topic in medicinal chemistry. 1,3,5-Trisubstituted pyrazoles carrying benzenesulfonamide were evaluated against physiologically abundant cytosolic hCA I and hCA II and trans-membrane, tumor-associated hCA IX isoforms by a stopped-flow CO2 hydrase method. Their in vitro cytotoxicities were screened against human oral squamous cell carcinoma (OSCC) cell lines (HSC-2) and human mesenchymal normal oral cells (HGF) via 3-(4,5- Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) test. Compounds 6, 8, 9, 11, and 12 showed low nanomolar hCA II inhibitory potency with Ki < 10 nM, whereas compounds 9 and 12 displayed Ki < 10 nM against hCA IX isoenzyme when compared with reference Acetazolamide (AZA). Compound 9, 4-(3-(hydrazinecarbonyl)-5-(4-nitrophenyl)-1H-pyrazol-1-yl)benzenesulfonamide, can be considered as the most selective hCA IX inhibitor over off-target cytosolic isoenzymes hCA I and hCA II with the lowest Ki value of 2.3 nM and selectivity ratios of 3217 (hCA I/hCA IX) and 3.9 (hCA II/hCA IX). Isoform selectivity profiles were also discussed using in silico modelling. Cytotoxicity results pointed out that compounds 5 (CC50 = 37.7 μM) and 11 (CC50 = 58.1 μM) can be considered as lead cytotoxic compounds since they were more cytotoxic than 5- Fluorouracil (5-FU) and Methotrexate (MTX).

Starting from the molecular simplification of (R) 4-(3,4-dibenzylpiperazine-1-carbonyl)benzenesulfonamide 9a, a compound endowed with selectivity for human Carbonic Anhydrase (hCA) IV, a series of piperazines and 4-aminopiperidines carrying a 4-sulfamoylbenzamide moiety as Zn-binding group have been designed and tested on human isoforms hCA I, II, IV and IX, using a stopped flow CO2 hydrase assay. The aim of the work was to derive structure-activity relationships useful for designing isoform selective compounds. These structural modifications changed the selectivity profile of the analogues from hCA IV to hCA I and II, and improved potency. Several of the new compounds showed subnanomolar activity on hCA II. X-ray crystallography of ligand-hCAII complexes was used to compare the binding modes of the new piperazines and the previously synthesized 2-benzyl-piperazine analogues, explaining the inhibition profiles.