Glecaprevir/pibrentasvir for the treatment of chronic hepatitis C: design, development, and place in therapy

Direct-acting antiviral (DAA) therapy has changed the landscape of hepatitis C virus (HCV) management and has changed the focus to the possibility of HCV elimination in the near future. Glecaprevir, an NS3/4A protease inhibitor, and pibrentasvir, an HCV NS5A inhibitor, have addressed many of the existing shortcomings in the DAA therapy spectrum. This combination has proven to be a highly efficacious pan-genotypic DAA with a high barrier to resistance as a once-daily, all-oral medication. This review explores the design and development of glecaprevir and pibrentasvir, its place in current HCV management in the midst of a myriad of DAA therapy options, and also remaining challenges.

Designing of promising medicinal scaffolds for Alzheimer's disease through enzyme inhibition, lead optimization, molecular docking and dynamic simulation approaches

In the designed research work, a series of 2-furoyl piperazine based sulfonamide derivatives were synthesized as therapeutic agents to target the Alzheimer's disease. The structures of the newly synthesized compounds were characterized through spectral analysis and their inhibitory potential was evaluated against butyrylcholinesterase (BChE). The cytotoxicity of these sulfonamides was also ascertained through hemolysis of bovine red blood cells. Furthermore, compounds were inspected by Lipinki Rule and their binding profiles against BChE were discerned by molecular docking. The protein fluctuations in docking complexes were recognized by dynamic simulation. From our in vitro and in silico results 5c, 5j and 5k were identified as promising lead compounds for the treatment of targeted disease.

Sulfonamides incorporating piperazine bioisosteres as potent human carbonic anhydrase I, II, IV and IX inhibitors

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.

Synthesis, Fungicidal Activity and SAR of 2-Thiazolamide/Pyrazolamide-Cyclohexylsulfonamides against Botrytis cinerea

In order to explore more efficient sulfonamides against Botrytis cinereal, 36 novel cyclohexylsulfonamides were synthesized by N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (EDCI) and 1-hydroxybenzotriazole (HOBt) condensation reaction using chesulfamide as a lead compound, introducing thiazole and pyrazole active groups. Their structures were characterized by ¹H-NMR, ¹³C-NMR, mass spectrum (MS), and elemental analysis. Compound III -31 was further confirmed by X-ray single crystal diffraction. The in vitro and in vivo fungicidal activities against B. cinerea were evaluated by three bioassay methods. The results of mycelial growth demonstrated that median effective concentration (EC₅₀) values of nine compounds were close to boscalid (EC₅₀ = 1.72 µg/mL) and procymidone (EC₅₀ = 1.79 µg/mL) against B. cinerea (KZ-9). In the spore germination experiment, it was found that compounds III-19 and III-31 inhibited germination 93.89 and 98.00%, respectively; at 10 µg/mL, they approached boscalid (95.97%). In the tomato pot experiment, the control effects of two compounds (III-21 and III-27) were 89.80 and 87.90%, respectively, at 200 µg/mL which were significantly higher than boscalid (81.99%). The structure–activity relationship (SAR) was also discussed, which provided a valuable idea for developing new fungicides.

Ureidobenzenesulfonamides as efficient inhibitors of carbonic anhydrase II

Sulfonamides represent an important class of drugs because of their inhibitory effect on carbonic anhydrases (CAs). We therefore synthesized several ureidobenzenesulfonamides and evaluated their bCA II inhibition for their potential use as anti-glaucoma gents. Since these compounds must not show cytotoxic effects, their cytotoxic potential against several human tumor cell lines and non-malignant fibroblasts was investigated. Several fluorophenyl substituted sulfonamides were efficient inhibitors of bCA II. Only one benzylphenyl substituted sulfonamide, however, showed a remarkable selectivity for HT29 colorectal carcinoma cells while being significantly less cytotoxic to non-malignant fibroblasts.

Practical access to axially chiral sulfonamides and biaryl amino phenols via organocatalytic atroposelective N-alkylation

The importance of axial chirality in enantioselective synthesis has been widely recognized for decades. The practical access to certain structures such as biaryl amino phenols known as NOBINs in enantiopure form, however, still remains a challenge. In drug delivery, the incorporation of axially chiral molecules in systematic screening has also received a great deal of interest in recent years, which calls for innovation and practical synthesis of structurally different axially chiral entities. Herein we present an operationally simple catalytic N-alkylation of sulfonamides using commercially available chiral amine catalysts to deliver two important classes of axially chiral compounds: structurally diverse NOBIN analogs as well as axially chiral N-aryl sulfonamides in excellent enantiopurity. Structurally related chiral sulfonamide has shown great potential in drug molecules but enantioselective synthesis of them has never been accomplished before. The practical catalytic procedures of our methods also bode well for their wide application in enantioselective synthesis.

Synthesis, Molecular Docking Analysis, and Carbonic Anhydrase Inhibitory Evaluations of Benzenesulfonamide Derivatives Containing Thiazolidinone

To find novel human carbonic anhydrase (hCA) inhibitors, we synthesized thirteen compounds by combining thiazolidinone with benzenesulfonamide. The result of the X-ray single-crystal diffraction experiment confirmed the configuration of this class of compounds. The enzyme inhibition assays against hCA II and IX showed desirable potency profiles, as effective as the positive controls. The docking studies revealed that compounds (2) and (7) efficiently bound in the active site cavity of hCA IX by forming sufficient interactions with active site residues. The fragment of thiazolidinone played an important role in the binding of the molecules to the active site.

Novel benzenesulfonamide and 1,2-benzisothiazol-3(2H)-one-1,1-dioxide derivatives as potential selective COX-2 inhibitors

Two new series of 1,2-benzisothiazol-3(2H)-one-1,1-dioxide derivatives containing either five membered heterocyclic rings or aryl hydrazones were synthesized and evaluated for their in vitro COX-1/COX-2 inhibitory activity. In vivo anti-inflammatory evaluation revealed that benzenesulfonamides bearing pyrazole moiety 19, 20 and its cyclized form 23 exhibited the highest anti-inflammatory activity with comparable potency to celecoxib. Furthermore, the ulcerogenic activity evaluation showed that compounds 19, 20 and 23 exerted the minimal ulcer index in comparison to indomethacin as a reference drug. Docking studies of the most selective COX-2 derivatives were also carried out against COX-2 active site. Benzenesulfonamide derivatives 19 and 20 displayed higher predicted binding affinities inside the COX-2 active site. Molecular modelling simulation and drug likeness studies showed good agreement with the obtained biological evaluation.

Benzensulfonamides bearing spyrohydantoin moieties act as potent inhibitors of human carbonic anhydrases II and VII and show neuropathic pain attenuating effects

Carbonic Anhydrases have been recently validated as novel therapeutic targets in neuropathic pain. In this study, we combine the anticonvulsant propriety of spyrohydantoin and the CA inhibitor moiety of benzenesulfonamide to synthesize a novel series of spyrohydantoin bearing sulfonamides with strong activity against hCA II and VII. These isoforms are present in the nervous system and largely expressed both at the central as well as at peripheral level and can be modulated for pain relief. The crystal structures of hCA II in complex with selected compounds 5a-c demonstrate the importance of the tail in the binding modes within the isoform. Finally, in vivo, in an animal model of oxaliplatin induced neuropathy, compounds with organoselenium tails (8b-c) showed potent neuropathic pain attenuating effects. Taken together, these data strongly suggest the translational utility of these inhibitors as novel pain relievers.

Click-tailed benzenesulfonamides as potent bacterial carbonic anhydrase inhibitors for targeting Mycobacterium tuberculosis and Vibrio cholerae

A series of 1,2,3-triazole-bearing benzenesulfonamides was assessed for the inhibition of carbonic anhydrases (CA, EC 4.2.1.1) from bacteria Vibrio cholerae (VchCAα and VchCAβ) and Mycobacterium tuberculosis (β-mtCA3). Growing resistance phenomena against existing antimicrobial drugs are globally spreading and highlight a urgent need of agents endowed with alternative mechanisms of action. Two global WHO strategies aim to reduce cholera deaths by 90% and eradicate the tuberculosis epidemic by 2030. The derivatives here reported represent interesting leads towards the optimization of new antibiotic agents showing excellent inhibitory efficiency and selectivity for the target CAs over the human (h) off-target isoform hCA I. In detail, the first subset of derivatives potently inhibits VchCAα in a low nanomolar range (KIs between 0.72 and 22.6 nM). Compounds of a second subset, differing from the first one for the position of the spacer between benzenesulfonamide and triazole, preferentially inhibit VchCAβ (KIs in the range 54.8-102.4 nM) and β-mtCA3 (KIs in the range 28.2-192.5 nM) even more than the clinically used AAZ, used as the standard.

Benzenesulfonamides incorporating nitrogenous bases show effective inhibition of β-carbonic anhydrases from the pathogenic fungi Cryptococcus neoformans, Candida glabrata and Malassezia globosa

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.

Pyridazinone-substituted benzenesulfonamides display potent inhibition of membrane-bound human carbonic anhydrase IX and promising antiproliferative activity against cancer cell lines

An expanded set of pyridazine-containing benzene sulfonamides was investigated for inhibition of four human carbonic anhydrase isoforms, which revealed a pronounced inhibition trend toward hCA IX, a cancer-related, membrane-bound isoform of the enzyme. Comparison of antiproliferative effects of these compounds against cancer (PANC-1) and normal (ARPE-19) cells at 50 μM concentration narrowed the selection of compounds to the eight which displayed selective growth inhibition toward the cancer cells. More detailed investigation in concentration-dependent mode against normal (ARPE-19) and two cancer cell lines (PANC-1 and SK-MEL-2) identified two lead compounds one of which displayed a notable cytotoxicity toward pancreatic cancer cells while the other targeted the melanoma cells. These findings significantly expand the knowledge base concerning the hCA IX inhibitors whose inhibitory potency against a recombinant enzyme translates into selective anticancer activity under hypoxic conditions which are aimed to model the environment of a growing tumor.

Benzenesulfonamides act as open-channel blockers on KV3.1 potassium channel

KV3.1 blockers can serve as modulators of the rate of action potential firing in neurons with high rates of firing such as those of the auditory system. We studied the effects of several bioisosteres of N-alkylbenzenesulfonamides, and molecules derived from sulfanilic acid on KV3.1 channels, heterologously expressed in L-929 cells, using the whole-cell patch-clamp technique. Only the N-alkyl-benzenesulfonamides acted as open-channel blockers on KV3.1, while molecules analogous to PABA (p-aminobenzoic acid) and derived from sulfanilic acids did not block the channel. The IC50 of six N-alkyl-benzenesulfonamides ranged from 9 to 55 µM; and the Hill coefficient suggests the binding of two molecules to block KV3.1. Also, the effects of all molecules on KV3.1 were fully reversible. We look for similar features amongst the molecules that effectively blocked the channel and used them to model a blocker prototype. We found that bulkier groups and amino-lactams decreased the effectiveness of the blockage, while the presence of NO2 increased the effectiveness of the blockage. Thus, we propose N-alkylbenzenesulfonamides as a new class of KV3.1 channel blockers.

Exploring structural properties of potent human carbonic anhydrase inhibitors bearing a 4-(cycloalkylamino-1-carbonyl)benzenesulfonamide moiety

Guided by the crystal structure of 4-(3,4-dihydroquinolin-1(2H)-ylcarbonyl)benzenesulfonamide 3 in complex with hCA II (PDB code 4Z0Q), a novel series of cycloalkylamino-1-carbonylbenzenesulfonamides was designed and synthesized. Thus, we replaced the quinoline ring with an azepine/piperidine/piperazine nucleus and introduced further modifications on cycloalkylamine nucleus by means the installation of hydrophobic/hydrophilic functionalities able to establish additional contacts in the middle area of the enzyme cavity. Among the synthesized compounds, the derivatives 7a, 7b, 8b exhibited a remarkable inhibition for hCA II and the brain-expressed hCA VII in subnanomolar range. The binding of these molecules to the target enzymes was characterized by means of a crystallographic analysis, providing a clear snapshot of the most important interactions established by this class of inhibitors into the hCA II and hCA VII catalytic site. Notably, our results showed that the benzylpiperazine tail of compound 8b is oriented both in hCA II and in hCA VII toward a poorly explored region of the active site. These features should be further investigated for the design of new isoform selective CA inhibitors.

Design, synthesis and biological evaluation of bifunctional inhibitors of membrane type 1 matrix metalloproteinase (MT1-MMP)

Collagen degradation and proMMP-2 activation are major functions of MT1-MMP to promote cancer cell invasion. Since both processes require MT1-MMP homodimerization on the cell surface, herein we propose that the use of bifunctional inhibitors of this enzyme could represent an innovative approach to efficiently reduce tumor growth. A small series of symmetrical dimers derived from previously described monomeric arylsulfonamide hydroxamates was synthesized and tested in vitro on isolated MMPs. A nanomolar MT1-MMP inhibitor, compound 6, was identified and then submitted to cell-based assays on HT1080 fibrosarcoma cells. Dimer 6 reduced MT1-MMP-dependent proMMP-2 activation, collagen degradation and collagen invasion in a dose-dependent manner with better results even compared to its monomeric analogue 4. This preliminary study suggests that dimeric MT1-MMP inhibitors might be further developed and exploited as an alternative tool to reduce cancer cell invasion.

Synthesis of some new N-(alkyl/aralkyl)-N-(2,3-dihydro-1,4-benzodioxan-6-yl)-4-chlorobenzenesulfonamides as possible therapeutic agents for Alzheimer's disease and Type-2 Diabetes

In the current research work, a series of new N-(alkyl/aralkyl)-N-(2,3-dihydro-1,4-benzodioxan-6-yl)-4-chlorobenzenesulfonamides has been synthesized by reacting 1,4-benzozzdioxan-6-amine (1) with 4-chlorobenzenesulfonyl chloride (2) to yield N-(2,3-dihydro-1,4-benzodioxan-6-yl)-4-chlorobenzenesulfonamide (3) which was further reacted with different alkyl/aralkyl halides (4a-n) to afford the target compounds (5a-n). Structures of the synthesized compounds were confirmed by IR, 1H-NMR, EI-MS spectral techniques and CHN analysis data. The results of enzyme inhibition showed that the molecules, N-2-phenethyl-N-(2,3-dihydro-1,4-benzodioxin-6-yl)-4-chlorobenzenesulfonamide (5j) and N-(1-butyl)-N-(2,3-dihydro-1,4-benzodioxin-6-yl)-4-chlorobenzenesulfonamide (5d), exhibited moderate inhibitory potential against acetylcholinesterase with IC50 values 26.25±0.11 μM and 58.13±0.15 μM respectively, whereas, compounds N-benzyl-N-(2,3-dihydro-1,4-benzodioxin-6-yl)-4-chlorobenzenesulfonamide (5i) and N-(pentane-2-yl)-N-(2,3-dihydro-1,4-benzodioxin-6-yl)-4-chlorobenzenesulfonamide (5f) showed moderate inhibition against α-glucosidase enzyme as evident from IC50 values 74.52±0.07 and 83.52±0.08 μM respectively, relative to standards Eserine having IC50 value of 0.04±0.0001 μM for cholinesterases and Acarbose having IC50 value 38.25±0.12 μM for α-glucosidase, respectively.

Catalytic Radical Process for Enantioselective Amination of C(sp3 )-H Bonds

A new catalytic radical system involving CoII -based metalloradical catalysis is effective in activating sulfamoyl azides for enantioselective radical 1,6-amination of C(sp3 )-H bonds, affording six-membered chiral heterocyclic sulfamides in high yields with excellent enantioselectivities. The CoII -catalyzed C-H amination features an unusual degree of functional-group tolerance and chemoselectivity. The unique reactivity and stereoselectivity is attributed to the underlying stepwise radical pathway. The resulting optically active cyclic sulfamides can be readily converted into synthetically useful chiral 1,3-diamine derivatives without loss in enantiopurity.

Antileishmanial activity of sulphonamide nanoemulsions targeting the β-carbonic anhydrase from Leishmania species

The β-carbonic anhydrase (CA, EC 4.2.1.1) from Leishmania spp. (LdcCA) is effectively inhibited by aromatic/heterocyclic sulphonamides, in the low nanomolar range, but no in vitro antileishmanial activity was detected for such compounds. We formulated some of these sulphonamides as nanoemulsions (NEs) in clove oil, and tested them in vitro against Leishmania infantum MHOM/BR/1974/PP75 and Leishmania amazonensis IFLA/BR/1967/PH8 strains. Interesting inhibitory concentrations IC50 were observed for some of the sulphonamides NEs, with IC50 as low as 3.90 µM (NE-3F) and 2.24 µM (NE-5B) for L. amazonensis and 3.47 µM (NE-5B) for L. infantum. Some of the investigated NEs displayed toxicity for macrophages beyond the parasites. For the same nonoemulsions, a selective index (SI) greater than for Amphotericin B. Haemolytic assay using human red blood cells indicate that the NEs were less cytotoxic than amphotericin B, a widely used antifungal agent. NEs demonstrated to be an excellent strategy for increasing the penetration of these hydrophilic drugs through membranes, with a huge increase of efficacy over the sulphonamide CA inhibitor (CAI) alone.

Inhibition studies on a panel of human carbonic anhydrases with N1-substituted secondary sulfonamides incorporating thiazolinone or imidazolone-indole tails

Being the primary sulfonamide among the most efficient zinc binding group (ZBG) to design inhibitors for the metallo-enzymes carbonic anhydrases (CA, EC 4.2.1.1), herein, we propose an investigation on four physiologically important human (h) CAs (hCA I, II, IV, and IX) with N1-substituted secondary sulfonamides incorporating thiazolinone or imidazolone-indole tails. The effect of the functionalisation of the sulfonamide group with five different substitution patterns, namely acetyl, pyridine, thiazole, pyrimidine, and carbamimidoyl, was evaluated in relation to the inhibition profile of the corresponding primary sulfonamide analogues. With most of these latter being nanomolar inhibitors of all four considered isoforms, a totally counterproductive effect on the inhibition potency can be ascribed to N1-functionalisations of the ZBG primary sulfonamide structure with pyridine, thiazole, and pyrimidine moieties. On the other hand, incorporation of less hindered groups, such as sulfonylacetamides and sulfonylguanidines, maintained a certain degree of activity dependent on the tailing moiety, with KIs spanning in the low micromolar range.

Selective inhibition of carbonic anhydrase-IX by sulphonamide derivatives induces pH and reactive oxygen species-mediated apoptosis in cervical cancer HeLa cells

Selective inhibition with sulphonamides of carbonic anhydrase (CA) IX reduces cell proliferation and induces apoptosis in human cancer cells. The effect on CA IX expression of seven previously synthesised sulphonamide inhibitors, with high affinity for CA IX, as well as their effect on the proliferation/apoptosis of cancer/normal cell lines was investigated. Two normal and three human cancer cell lines were used. Treatment resulted in dose- and time-dependent inhibition of the growth of various cancer cell lines. One compound showed remarkably high toxicity towards CA IX-positive HeLa cells. The mechanisms of apoptosis induction were determined with Annexin-V and AO/EB staining, cleaved caspases (caspase-3, caspase-8, caspase-9) and cleaved PARP activation, reactive oxygen species production (ROS), mitochondrial membrane potential (MMP), intracellular pH (pHi), extracellular pH (pHe), lactate level and cell cycle analysis. The autophagy induction mechanisms were also investigated. The modulation of apoptotic and autophagic genes (Bax, Bcl-2, caspase-3, caspase-8, caspase-9, caspase-12, Beclin and LC3) was measured using real time PCR. The positive staining using γ-H2AX and AO/EB dye, showed increased cleaved caspase-3, caspase-8, caspase-9, increased ROS production, MMP and enhanced mRNA expression of apoptotic genes, suggesting that anticancer effects are also exerted through its apoptosis-inducing properties. Our results show that such sulphonamides might have the potential as new leads for detailed investigations against CA IX-positive cervical cancers.

Inhibition studies of Brucella suis β-carbonic anhydrases with a series of 4-substituted pyridine-3-sulphonamides

The two β-carbonic anhydrases (CAs, EC 4.2.1.1) from the pathogenic bacterium Brucella suis, BsuCA1 and BsuCA2, were investigated for their inhibition profile with a series of pyridine-3-sulphonamide derivatives incorporating 4-hetaryl moieties. BsuCA1 was effectively inhibited by these sulphonamides with inhibition constants ranging between 34 and 624 nM. BsuCA2 was less sensitive to these inhibitors, with KIs in the range of 62 nM - > 10 µM. The nature of the 4-substituent present on the pyridine ring was the main factor influencing the inhibitory profile against both isoforms, with 4-halogenophenylpiperazin-1-yl and 3,4,5-trisubstituted-pyrazol-1-yl derivatives showing the most effective inhibition. Some of these sulphonamides were most effective bacterial CA than human (h) CA I and II inhibitors, making them selective for the prokaryotic enzymes. Investigation of bacterial CA inhibitors may be relevant for finding antibiotics with a new mechanism of action compared to the clinically used agents for which substantial drug resistance emerged.

Nanoemulsions of sulfonamide carbonic anhydrase inhibitors strongly inhibit the growth of Trypanosoma cruzi

Sulfonamide carbonic anhydrase (CA, EC 4.2.1.1) inhibitors targeting the α-class enzyme from the protozoan pathogen Trypanosoma cruzi, responsible of Chagas disease, were recently reported. Although many such derivatives showed low nanomolar activity in vitro, they were inefficient anti-T. cruzi agents in vivo. Here, we show that by formulating such sulfonamides as nanoemulsions in clove (Eugenia caryophyllus) oil, highly efficient anti-protozoan effects are observed against two different strains of T. cruzi. These effects are probably due to an enhanced permeation of the enzyme inhibitor through the nanoemulsion formulation, interfering in this way with the life cycle of the pathogen either by inhibiting pH regulation or carboxylating reactions in which bicarbonate/CO2 are involved. This type of formulation of sulfonamides with T. cruzi CA inhibitory effects may lead to novel therapeutic approaches against this orphan disease.

Evaluation of sulphonamide derivatives acting as inhibitors of human carbonic anhydrase isoforms I, II and Mycobacterium tuberculosis β-class enzyme Rv3273

A series of novel sulphonamide derivatives was obtained from sulphanilamide which was N4-alkylated with ethyl bromoacetate followed by reaction with hydrazine hydrate. The hydrazide obtained was further reacted with various aromatic aldehydes. The novel sulphonamides were characterised by infrared, mass spectrometry, 1H- and 13C-NMR and purity was determined by high-performance liquid chromatography (HPLC). Human (h) carbonic anhydrase (CA, EC 4.2.1.1) isoforms hCA I and II and Mycobacterium tuberculosis β-CA encoded by the gene Rv3273 (mtCA 3) inhibition activity was investigated with the synthesised compounds which showed promising inhibition. The KIs were in the range of 54.6 nM-1.8 µM against hCA I, in the range of 32.1 nM-5.5 µM against hCA II and of 127 nM-2.12 µM against mtCA 3.

Sulfonamide-Trapping Reactions of Thermally Generated Benzynes

Reactions of tethered, tertiary sulfonamides with thermally generated benzynes are reported. Typically, the N-S bonds in the substrates cleave, and saturated heterocycles [tetrahydroquinolines ( n = 2) and indolines ( n = 1)] are formed. The process is accompanied by either sulfonyl transfer or desulfonylation from a zwitterionic intermediate, with the favored pathway being largely dependent upon the size (5- vs 6-membered) of the N-containing ring in the zwitterion.

SLC-0111 enaminone analogs, 3/4-(3-aryl-3-oxopropenyl) aminobenzenesulfonamides, as novel selective subnanomolar inhibitors of the tumor-associated carbonic anhydrase isoform IX

SLC-0111, an ureido substituted benzenesulfonamide, is a selective carbonic anhydrase (CA, EC 4.2.1.1) IX inhibitor that is currently in Phase I/II clinical trials for the treatment of advanced hypoxic tumors complicated with metastases. Herein we report the synthesis of two series of 3/4-(3-aryl-3-oxopropenyl) aminobenzenesulfonamides 5a-i and 6a-j as SLC-0111 enaminone congeners. The prepared enaminones were in vitro investigated as inhibitors of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1) isoforms hCA I, II, IV and IX, using a stopped-flow CO₂ hydrase assay. All these isoforms were inhibited by the enaminones reported here in variable degrees. The target tumor-associated isoform hCA IX was undeniably the most affected one (K_Is: 0.21-7.1 nM), with 6- to 21-fold enhanced activity than SLC-0111 (K_I = 45 nM). All the prepared enaminones displayed interesting selectivity towards hCA IX over hCA I (SI: 32 - >35714), hCA II (SI: 2 - 1689) and hCA IV (SI: 11 - >45454). Of particular interest, bioisosteric replacement of phenyl tail with the bulkier 2-naphthyl tail, sulfonamide 6h, achieved the higher II/IX selectivity herein reported with SI of 1689.