o-Benzenedisulfonimido–sulfonamides are potent inhibitors of the tumor-associated carbonic anhydrase isoforms CA IX and CA XII

By using phthalimido-substituted aromatic sufonamides as lead molecules, a series of new sulfonamides incorporating ortho-benzenedisulfonimide moieties have been synthesized and tested against the human (h) cytosolic carbonic anhydrase (CA, EC 4.2.1.1) isozymes hCA I and hCA II and the transmembrane, tumor-associated isozymes hCA IX and hCA XII. All these compounds showed K_i values lower than 100 nM and many of them showed better K_is than the reference compound acetazolamide, a clinically used sulfonamide. The tumor-associated isozymes were better inhibited than the cytosolic ones. A molecular docking within the active site of some CA isoforms, such as hCA I, explained these findings, as the benzenedisulfonimide moiety makes favorable interactions (hydrogen bonds) with amino acid residues involved in binding of inhibitors, such as Gln92, His67, and His64.     

A class of carbonic anhydrase IX/XII – selective carboxylate inhibitors

Abstract

A small series of 2,4-dioxothiazolidinyl acetic acids was prepared from thiourea, chloroacetic acid, aromatic aldehydes, and ethyl-2-bromoacetate. They were assayed for the inhibition of four physiologically relevant carbonic anhydrase (CA, EC 4.2.1.1) isoforms of human (h) origin, the cytosolic hCA I and II, and the transmembrane hCA IX and XII, involved among others in tumorigenesis (hCA IX and XII) and glaucoma (hCA II and XII). The two cytosolic isoforms were not inhibited by these carboxylates, which were also rather ineffective as hCA IX inhibitors. On the other hand, they showed submicromolar hCA XII inhibition, with K_Is in the range of 0.30–0.93?µM, making them highly CA XII-selective inhibitors.     

Vanillin enones as selective inhibitors of the cancer associated carbonic anhydrase isoforms IX and XII. The out of the active site pocket for the design of selective inhibitors?

New C-glycosides and α,β-unsaturated ketones incorporating the 4-hydroxy-3-methoxyphenyl (vanillin) moiety as inhibitors of carbonic anhydrase (CA, EC 4.2.1.1) isoforms have been investigated. The inhibition profile of these compounds is presented against four human CA (hCA) isozymes, comprising hCAs I and II (cytosolic, ubiquitous enzymes) and hCAs IX and XII (tumour associated isozymes). Docking analysis of the inhibitors within the active sites of these enzymes has been performed and is discussed, showing that the observed selectivity could be explained in terms of an alternative pocket out of the CA active site where some of these compounds may bind. Several derivatives were identified as selective inhibitors of the tumour-associated hCA IX and XII. Their discovery might be a step in the strategy for finding an effective non-sulfonamide CA inhibitor useful in therapy/diagnosis of hypoxic tumours or other pathologies in which CA isoforms are involved.     

N-β-glycosyl sulfamides are selective inhibitors of the cancer associated carbonic anhydrase isoforms IX and XII

The transmembrane isoforms of carbonic anhydrase (CA IX and XII) have been shown to be linked to carcinogenesis and their inhibition to arrest primary tumor and metastases growth. In this Letter, we present a series of peracetylated and deprotected N-β-glycosyl sulfamides that were tested for the inhibition of 4 carbonic anhydrase isoforms: the cytosolic hCA I and hCA II and transmembrane tumor-associated IX and XII. Compounds 1-4 and 6-8 selectively target cancer-associated CAs (IX and XII) with K_Is in the low nanomolar range.     

Carbonic anhydrase inhibitors. Inhibition of the transmembrane isozyme XII with sulfonamides—a new target for the design of antitumor and antiglaucoma drugs?

The inhibition of a newly cloned human carbonic anhydrase (CA, EC 4.2.1.1), isozyme XII (hCA XII), has been investigated with a series of sulfonamides, including some clinically used derivatives (acetazolamide, methazolamide, ethoxzolamide, dichlorophenamide, dorzolamide, brinzolamide, benzolamide, and sulpiride, or indisulam, a compound in clinical development as antitumor drug), as well as the sulfamate antiepileptic drug topiramate. Some simple amino-/hydrazine-/hydroxy-substituted aromatic/heterocyclic sulfonamides have also been included in the study. All types of activity have been detected, with several medium potency inhibitors (K(I)s in the range of 34-220 nM), whereas ethoxzolamide and several halogenated sulfanilamides showed stronger potency, with K(I)s in the range of 11-22 nM. The antiglaucoma sulfonamides used clinically, except dichlorophenamide, which is a moderate inhibitor (K(I) of 50 nM), as well as topiramate, indisulam, and sulpiride behave as very potent hCA XII inhibitors, with K(I)s in the range of 3.0-5.7 nM. Several subnanomolar inhibitors (K(I)s in the range of 0.30-0.85 nM) have also been detected. Compounds with excellent selectivity against hCA XII over hCA II have been found, showing selectivity ratios in the range of 177.7-566.7. Apparently, hCA XII is a target of the antiglaucoma sulfonamides, and potent hCA XII inhibitors may be developed/used for the management of hypoxic tumors, together with inhibitors of the other tumor-associated isozyme, CA IX.     

N-Sulfamoylphenyl- and N-sulfamoylphenyl-N-thiazolyl-β-alanines and their derivatives as inhibitors of human carbonic anhydrases

A series of N-substituted and N,N-disubstituted β-amino acids and their derivatives bearing benzenesulfonamide moiety were designed and synthesized in search of compounds that would be high-affinity and selective inhibitors of human carbonic anhydrases (CA). There are 12 catalytically active human CA isoforms, the cytosolic CA I, CA II, CA III, CA VII, and CA XIII, secreted CA VI, the mitochondrial CA VA and CA VB, membrane-associated CA IV, and transmembrane CA IX, CA XII, and CA XIV. The di-bromo meta-substituted compounds exhibited low nanomolar dissociation constants and over 10-fold selectivity for mitochondrial isozyme CA VB, implicated in diseases of the central nervous system and obesity. These compounds can be used for further development as inhibitors of significant binding affinity and selectivity towards CA VB isozyme.     

Discovery of Strecker-type α-aminonitriles as a new class of human carbonic anhydrase inhibitors using differential scanning fluorimetry

A new type of carbonic anhydrase inhibitors was identified via differential scanning fluorimetry (DSF) screening. The compounds displayed interesting inhibition profile against human carbonic anhydrase isoforms I, II, IX and XII with an obvious selectivity displayed by one compound toward carbonic anhydrase (CA) IX, an established anti-cancer target. A hypothetical mechanism of inhibitory action by the Strecker-type α-aminonitriles has been proposed.     

A concise synthesis and evaluation of new malonamide derivatives as potential α-glucosidase inhibitors

A series of new malonamide derivatives were synthesized by Michael addition reaction of N¹,N³-di(pyridin-2-yl)malonamide into α,β-unsaturated ketones mediated by DBU in DCM at ambient temperature. The inhibitory potential of these compounds in vitro, against α-glucosidase enzyme was evaluated. Result showed that most of malonamide derivatives were identified as a potent inhibitors of α-glucosidase enzyme. Among all the compounds, 4K (IC₅₀ = 11.7 ± 0.5 μM) was found out as the most active one compared to standard drug acarbose (IC₅₀ = 840 ± 1.73 μM). Further cytotoxicity of 4a–4m were also evaluated against a number of cancer and normal cell lines and interesting results were obtained.     

A quantitative structure–activity relationship study on some aromatic/heterocyclic sulfonamides and their charged derivatives acting as carbonic anhydrase inhibitors

A quantitative structure–activity relationship (QSAR) study is made on a series of aromatic/heterocyclic sulfonamides and their charged derivatives acting as carbonic anhydrase (CA) inhibitors. These compounds were studied by Scozzafava et al. (J. Med. Chem. 2000; 43: 292) for the selective inhibition of CAs—sulfonamides generally do not discriminate between different CA isozymes and hence exhibit many undesirable side effects when used as drugs against a particular disease. In this communication, an attempt has been made to investigate the physicochemical and structural properties that can make them selective for a given CA isozyme. Based on in vitro data reported by Scozzafava et al. against two cytosolic isozymes and one membrane-bound isozyme, the QSAR study has shown that uncharged compounds cannot be made selective for cytosolic or membrane-bound isozyme since in both the cases the compounds appear to follow the same mechanism of inhibition. However, for the charged compounds the polarizability of the molecule seems to greatly favor the inhibition of the membrane-bound enzyme, and hence they can be made selective for this enzyme by enhancing their polarizability, which is found to play no role in the inhibition of cytosolic enzymes.     

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 K_Is 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.     

A comprehensive review on synthesis and designing aspects of coumarin derivatives as monoamine oxidase inhibitors for depression and Alzheimer’s disease

Monoamine oxidase (MAO) enzyme inhibition is a crucial target for the management of depression and Alzheimer disease and inhibitors of MAO are the most important drugs for their management. Coumarins are a large family of compounds, of natural and synthetic origin, that exhibit a variety of pharmacological activities, including MAO inhibition. The current review highlights the design and synthetic methods of coumarin derivatives as well as coumarins obtained from plant source as MAO inhibitors for treatment of depression and Alzheimer disease with salient finding related to structure–activity relationship. The aim of present review is to find out natural as well as synthetic coumarins as MAO inhibitors.     

A new class of quinazoline-sulfonamides acting as efficient inhibitors against the α-carbonic anhydrase from Trypanosoma cruzi

Abstract

The protozoan parasite Trypanosoma cruzi is the agent responsible for trypanosomiasis (Chagas disease) in humans and other animals. It has been recently reported that this pathogen encodes for an α-class carbonic anhydrase (CA, EC 4.2.1.1), denominated TcCA, which was shown to be crucial for its life cycle. Inhibition studies of a class of 4-oxoquinazoline containing a benzensulfonamide moiety and their 4-thioxo bioisosteres against the protozoan enzyme TcCA are described here. Most of 4-oxoquinazoline sulfonamides showed nanomolar TcCA inhibition activity with K_Is in the same order of magnitude of acetazolamide (AAZ), whereas their thioxo bioisosters showed moderate anti-Trypanosoma CA potency with K_Is in the micromolar range. The discovery of compounds incorporating a 4-oxoquinazoline ring as a low-nanomolar TcCA inhibitor is quite promising and it may be useful for developing anti-Trypanosoma agents with a novel mechanism of action compared to the clinically used drugs (such as benznidazole, nifurtimox) for which significant resistance and serious adverse effects due to their high-toxicity appeared.     

Azolylthioacetamides as a potent scaffold for the development of metallo-β-lactamase inhibitors

In an effort to develop new inhibitors of metallo-β-lactamases (MβLs), twenty-eight azolylthioacetamides were synthesized and assayed against MβLs. The obtained benzimidazolyl and benzioxazolyl substituted 1–19 specifically inhibited the enzyme ImiS, and 10 was found to be the most potent inhibitor of ImiS with an IC₅₀ value of 15?nM. The nitrobenzimidazolyl substituted 20–28 specifically inhibited NDM-1, with 27 being the most potent inhibitor with an IC₅₀ value of 170?nM. Further studies with 10, 11, and 27 revealed a mixed inhibition mode with competitive and uncompetitive inhibition constants in a similar range as the IC₅₀ values. These inhibitors resulted in a 2–4-fold decrease in imipenem MIC values using E. coli cells producing ImiS or NDM-1. While the source of uncompetitive (possibly allosteric) inhibition remains unclear, docking studies indicate that 10 and 11 may interact orthosterically with Zn2 in the active site of CphA, while 27 could bridge the two Zn(II) ions in the active site of NDM-1 via its nitro group.     

Synthesis and biological evaluation of novel tris-chalcones as potent carbonic anhydrase,acetylcholinesterase, butyrylcholinesterase and α-glycosidase inhibitors

A novel class of fluoro-substituted tris-chalcones derivatives (5a-5i) was synthesized from phloroglucinol and corresponding benzaldehydes. A three step synthesis method was followed for the production of these tris-chalcone compounds. The structures of the newly synthesized compounds (5a-5i) were confirmed on the basis of IR, ¹H NMR, ¹³C NMR, and elemental analysis. The compounds’ inhibitory activities were tested against human carbonic anhydrase I and II isoenzymes (hCA I and hCA II), acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and α-glycosidase (α-Gly). These chalcone derivatives had K_i values in the range of 19.58–78.73 nM for hCA I, 12.23–41.70 nM for hCA II, 1.09–6.84 nM for AChE, 8.30–32.30 nM for BChE and 0.93 ± 0.20–18.53 ± 5.06 nM against α-glycosidase. These results strongly support the promising nature of the tris-chalcone scaffold as selective carbonic anhydrase, acetylcholinesterase, butyrylcholinesterase, and α-glycosidase inhibitor. Overall, due to these derivatives’ inhibitory potential on the tested enzymes, they are promising drug candidates for the treatment of diseases like glaucoma, leukemia, epilepsy; Alzheimer’s disease; type-2 diabetes mellitus that are associated with high enzymatic activity of carbonic anhydrase, acetylcholine esterase, butyrylcholinesterase, and α-glycosidase.     

The synthesis of novel sulfamides derived from β-benzylphenethylamines as acetylcholinesterase,butyrylcholinesterase and carbonic anhydrase enzymes inhibitors

In this study, a series of novel β-benzylphenethylamines and their sulfamide derivatives were synthesized starting from (Z)-2,3-diphenylacrylonitriles. Pd-C catalysed hydrogenation of diphenylacrylonitriles, reduction of propanenitriles with LiAlH₄ in the presence of AlCl₃ followed by addition of conc. HCl afforded β-benzylphenethylamine hydrochloride salts. The reactions of these amine hydrochloride salts with chlorosulfonyl isocyanate (CSI) in the presence of tert-BuOH and excess Et₃N gave sulfamoylcarbamates. Removing of Boc group from the synthesized sulfamoylcarbamates with trifluoroacetic acid (TFA) yielded novel sulfamides in good yields. These novel sulfamides derived from β-benzylphenethylamines were effective inhibitors of the cytosolic carbonic anhydrase I and II isoenzymes (hCA I and II), acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) with K_i values in the range of 0.278–2.260 nM for hCA I, 0.187–1.478 nM for hCA II, 0.127–2.452 nM for AChE and 0.494–1.790 nM for BChE. The inhibitory effects of the synthesized novel sulfamides derived from β-benzylphenethylamines were compared to those of acetazolamide and dorzolamide as clinical hCA I and II isoenzymes inhibitors and tacrine as a clinical AChE and BChE enzymes inhibitors. In addition to in vitro tests, molecular modeling approaches are implemented not only for prediction of the binding affinities of the compounds but also to study their inhibition mechanisms in atomic level at the catalytic domains.     

Synthesis of new bergenin derivatives as potent inhibitors of inflammatory mediators NO and TNF-α

Bergenin is an isocoumarin natural product which aides in fat loss, healthy weight maintenance, enhancing the lipolytic effects of norepinephrine, inhibiting the formation of interleukin 1α and cyclooxygenases-2. Here we describe the anti-inflammatory activity of new bergenin derivatives 1-15 in the respiratory burst assay. Bergenin was isolated from the crude extract of Mallotus philippenensis after repeated column chromatography and was then subjected to chemical derivatization. The structures of all compounds were elucidated by NMR and mass spectroscopic techniques. Compound 2 was also studied using single crystal X-ray diffraction. Compounds 4, (54.5±2.2%) 5 (47.5±0.5%) 5, and 15 (86.8±1.9%) showed significant (P≤0.005) NO inhibitory activities whereas 6, 7, 11, 12 and 13 displayed moderate inhibitory activities that ranges between 16% and 31%. Furthermore compounds 4 and 15, were discovered as significant (P≤0.005) TNF-α inhibitors with 98% and 96% inhibition, respectively, while compounds 3, 5, 7, 8, 11, and 12 showed low level of TNF-α inhibition (0.4-28%). Compounds 8, 13 and 15 exhibited moderate anti-inflammatory IC(50) activities with 212, 222, and 253 μM, respectively, compared to the standard anti-inflammatory drug indomethacin as well as the parent bergenin compound. No cytotoxic effects could be detected when the compounds were tested on 3T3 cells up to concentrations of 100 μM.     

Expression of transmembrane carbonic anhydrase isoenzymes IX and XII in normal human pancreas and pancreatic tumours

Carbonic anhydrase (CA) IX and XII are transmembrane isoenzymes which are expressed in several epithelia and overexpressed in some carcinomas. They have recently been linked to von Hippel-Lindau gene-mediated carcinogenesis in that both isoenzymes are downregulated by the product of the wild-type von Hippel-Lindau tumour suppressor gene. This paper describes the localisation of CA IX and XII in the normal human pancreas and pancreatic tumours. Both isoenzymes showed positive reaction in the basolateral plasma membrane of the normal acinar and ductal epithelia. The hyperplastic ductal epithelium in tumour specimens generally showed an increased staining for CA IX. Of 29 malignant tumours of exocrine pancreas, 10 showed moderate or strong immunoreaction for CA IX. The signal for CA XII remained weak in most malignant lesions. The present results show that both CA IX and XII are unevenly expressed in the ductal and acinar compartments of the human pancreas. The expression of these isoenzymes in a relatively low number of malignant tumour specimens suggests that they have a limited value in diagnostic evaluation of pancreatic carcinoma. However, the increased expression of CA IX in hyperplastic ductal epithelium may contribute to the pancreatic tumourigenesis.     

3D QSAR studies,pharmacophore modeling,and virtual screening of diarylpyrazole–benzenesulfonamide derivatives as a template to obtain new inhibitors,using human carbonic anhydrase II as a model protein

A 3D-QSAR modeling was performed on a series of diarylpyrazole-benzenesulfonamide derivatives acting as inhibitors of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). The compounds were collected from two datasets with the same scaffold, and utilized as a template for a new pharmacophore model to screen the ZINC database of commercially available derivatives. The datasets were divided into training, test, and validation sets. As the first step, comparative molecular field analysis (CoMFA), CoMFA region focusing and comparative molecular similarity indices analysis (CoMSIA) in parallel with docking studies were applied to a set of 41 human (h) CA II inhibitors. The validity and the prediction capacity of the resulting models were evaluated by leave-one-out (LOO) cross-validation approach. The reliability of the model for the prediction of possibly new CA inhibitors was also tested.