Carbonic anhydrase inhibitors. Inhibition of the cytosolic human isozymes I and II, and the transmembrane, tumor-associated isozymes IX and XII with substituted aromatic sulfonamides activatable in hypoxic tumors

Carbonic anhydrase IX: A tumor acidification switch in heterogeneity and chemokine regulation

The primary physiological process of respiration produces carbon dioxide (CO₂) that reacts with water molecules which subsequently liberates bicarbonate (HCO-₃) and protons. Carbonic anhydrases (CAs) are the primary catalyst involved in this conversion. More than 16 isoforms of human CAs show organ or subcellular specific activity. Dysregulation of each CA is associated with multiple pathologies. Out of these members, the overexpression of membrane-bound carbonic anhydrase IX (CAIX) is associated explicitly with hypoxic tumors or various solid cancers. CAIX helps tumors deal with higher CO₂ by sequestering it with bicarbonate ions and helping cancer cells to grow in a comparatively hypoxic or acidic environment, thus acting as a pH adaptation switch. CAIX-mediated adaptations in cancer cells include angiogenesis, metabolic alterations, tumor heterogeneity, drug resistance, and regulation of cancer-specific chemokines. This review comprehensively collects and describe the cancer-specific expression mechanism and role of CAIX in cancer growth, progression, heterogeneity, and its structural insight to develop future combinatorial targeted cancer therapies.

Synthesis of biaryl sultams using visible-light-promoted denitrogenative cyclization of 1,2,3,4-benzothiatriazine-1,1-dioxides

A novel approach has been reported for the preparation of biaryl sultams using visible-light-promoted denitrogenative cyclization of 1,2,3,4-benzothiatriazine-1,1-dioxides.

Synthesis of a new series of N⁴-substituted 4-(2-aminoethyl)benzenesulfonamides and their inhibitory effect on human carbonic anhydrase cytosolic isozymes I and II and transmembrane tumor-associated isozymes IX and XII

A series of novel N(4)-substituted 4-(2-aminoethyl)benzenesulfonamides 5-17 have been synthesized and investigated as inhibitors of four isoforms of zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1), that is the cytosolic CA I and II, and tumor-associated isozymes CA IX and XII. Against the human CA I investigated compounds displayed KI values from 96.3 to 3520 nM, toward hCA II at range of 18.1-2055 nM, while against hCA IX ranging from 5.9 to 419 nM and against hCA XII in the range of 4.0-414 nM. The very good inhibitory activity against tumor-associated hCA IX and hCA XII was found. The six new compounds displayed a powerful inhibitory potency toward hCA IX (K(I) = 5.9-10.7 nM) in comparison with the clinically used CAIs AAZ, MZA, EZA, DCP and IND (24-50 nM). The most potent hCA IX and hCA XII inhibitors 11 and 12 (K(I): 5.9 and 6.2 nM for hCA IX and 4.3 and 4.0 nM for hCA XII, respectively) belonged to the compounds with cationic character and presented meaningful affinity to the transmembrane isoforms hCA IX and XII than to physiologically dominant isozymes hCA I and II with the selectivity ratios hCA IX versus hCA II and hCA XII versus hCA II for 11 and 12 in the range of 10-15.

Carbonic anhydrase IX as an imaging and therapeutic target for tumors and metastases

Carbonic anhydrase IX (CAIX) which is a zinc containing metalloprotein, efficiently catalyzes the reversible hydration of carbon dioxide. It is constitutively up-regulated in several cancer types and has an important role in tumor progression, acidification and metastasis. High expression of CAIX generally correlates with poor prognosis and is related to a decrease in the disease-free interval following successful therapy. Therefore, it is considered as a prognostic indicator in oncology.In this review, we describe CAIX regulation and its role in tumor hypoxia, acidification and metastasis. In addition, the molecular imaging of CAIX and its potential for use in cancer detection, diagnosis, staging, and for use in following therapy response is discussed. Both antibodies and small molecular weight compounds have been used for targeted imaging of CAIX expression. The use of CAIX expression as an attractive and promising candidate marker for systemic anticancer therapy is also discussed.

Carbonic anhydrase inhibitors. Synthesis, and molecular structure of novel series N-substituted N'-(2-arylmethylthio-4-chloro-5-methylbenzenesulfonyl)guanidines and their inhibition of human cytosolic isozymes I and II and the transmembrane tumor-associated isozymes IX and XII

A series of novel N-substituted N'-(2-arylmethylthio-4-chloro-5-methylbenzenesulfonyl)guanidines 9-41 have been synthesized and investigated as inhibitors of four isoforms of zinc enzyme carbonic anhydrase (CA.EC 4.2.1.1), that is the cytosolic CA I and II, and cancer-associated isozymes CA IX and XII. Against the human CA I investigated compounds showed KI in the range of 87-6506 nM, toward hCA II ranging from 7.8 to 4500 nM, against hCA IX in the range of 4.7-416 nM and against hCA XII at range of 0.96-540 nM. Compounds 10, 12-14, 16, 18-20, 24-26, 31 and 32 exhibited a powerful inhibitory potency toward hCA IX (K(I) = 4.7-21 nM) in comparison to the reference sulfonamides AAZ, MZA, EZA, DCP and IND (K(I) = 24-50 nM). Compound 14 was the most potent inhibitor of hCA I (K(I) = 87 nM), hCA IX (K(I) = 4.7 nM) and hCA XII (K(I) = 0.96 nM), while 26 was the most effective inhibitor of hCA II (K(I) = 7.8 nM). The most promising compound 32 exerted the highest selectivity ratios toward hCA IX versus hCA I (hCA I/hCA IX = 261) and hCA II (hCA II/hCA IX = 26). The in vitro antitumor activity of compounds 10, 13, 14, 21, 22, 25, 32, 38 and 41 was evaluated at the US National Cancer Institute (NCI) against a panel of 60 human tumor cell lines. The most active antitumor agents 21 and 25, inhibiting 32-35 human tumor cell lines with GI₅₀ in the range of 2.1-5.0 μM also showed relatively high inhibitory activity toward hCA IX and XII with KI from 18 to 40 nM.

Synthesis of a new series of biologically interesting 6'-chloro-1',1'-dioxospiro[4H-benzo[d][1,3,7]oxadiazocine-4,3'(2'H)-[1,4,2]benzodithiazine]-2,6(1H,5H)dione derivatives

ABSTRACT

A series of 6'-chloro-1',1'-dioxospiro[4H-benzo[d][1,3,7]oxadiazocine-4,3'(2'H)-[1,4,2]benzodithiazine]-2,6(1H,5H)dione derivatives have been synthesized from isatoic anhydride and 3-(R2-amino)-1,4,2-benzodithiazine 1,1-dioxides. Some synthetic limitations are discussed on the basis of quantum chemical calculations performed by use of the Hartree-Fock method.

GRAPHICAL ABSTRACT

Insights towards sulfonamide drug specificity in α-carbonic anhydrases

Carbonic anhydrases (CAs, EC 4.2.1.1) are a group of metalloenzymes that play important roles in carbon metabolism, pH regulation, CO2 fixation in plants, ion transport etc., and are found in all eukaryotic and many microbial organisms. This family of enzymes catalyzes the interconversion of CO2 and HCO3(-). There are at least 16 different CA isoforms in the alpha structural class (α-CAs) that have been isolated in higher vertebrates, with CA isoform II (CA II) being ubiquitously abundant in all human cell types. CA inhibition has been exploited clinically for decades for various classes of diuretics and anti-glaucoma treatment. The characterization of the overexpression of CA isoform IX (CA IX) in certain tumors has raised interest in CA IX as a diagnostic marker and drug target for aggressive cancers and therefore the development of CA IX specific inhibitors. An important goal in the field of CA is to identify, rationalize, and design potential compounds that will preferentially inhibit CA IX over all other isoforms of CA. The variations in the active sites between isoforms of CA are subtle and this causes non-specific CA inhibition which leads to various side effects. In the case of CA IX inhibition, CA II along with other isoforms of CA provide off-target binding sites which is undesirable for cancer treatment. The focus of this article is on CA IX inhibition and two different structural approaches to CA isoform specific drug designing: tail approach and fragment addition approach.

2-Phenitidine derivatives as suitable inhibitors of butyrylcholinesterase

This manuscript reports the synthesis of a series of N-substituted derivatives of 2-phenitidine. First, the reaction of 2-phenitidine (1) with benzene sulfonyl chloride (2) yielded N-(2-ethoxyphenyl) benzenesulfonamide (3), which further on treatment with sodium hydride and alkyl halides (4a-g) furnished into new sulfonamides (5a-g). Second, the phenitidine reacted with benzoyl chloride (6) and acetyl chloride (8) to yield the reported N-benzoyl phenitidine (7) and N-acetyl phenitidine (9), respectively. These derivatives were characterized by infrared spectroscopy, ¹H-NMR, and EI-MS, and then screened against acetylcholinesterase, butylcholinesterase, and lipoxygenase enzyme, and were found to be potent inhibitors of butyrylcholinesterase alone.

Synthesis and molecular structure of novel 2-(alkylthio)-4-chloro-N-(4,5-dihydro-5-oxo-1H-1,2,4-triazol-3-yl)-5-methylbenzenesulfonamides with potential anticancer activity

ABSTRACT

A series of novel 4-chloro-N-(4,5-dihydro-5-oxo-1-R²-1H-1,2,4-triazol-3-yl)-5-methyl-2-(R¹-methylthio)benzenesulfonamide derivatives have been synthesized as potential anticancer agents. The in vitro antitumor activity of some compounds was evaluated in the US National Cancer Institute (NCI) against the NCI-60 cell line panel. The most prominent compound showed remarkable activity against 13 human tumor cell lines representing lung, colon, CNS, melanoma, ovarian, renal, prostate, and breast at low micromolar GI₅₀ level in the range of 1.9-3.0 μM.

GRAPHICAL ABSTRACT

Synthesis and in vitro activity of novel 2-(benzylthio)-4-chloro-5-(1,3,4-oxadiazol-2-yl)benzenesulfonamide derivatives

ABSTRACT

Two series of novel 4-chloro-2-(benzylthio)-5-(1,3,4-oxadiazol-2-yl)benzenesulfonamides and their N-aroyl derivatives have been synthesized and evaluated for in vitro anticancer activity against the full NCI-60 cell line panel. Most of the compounds exhibited antiproliferative activity. Among them a compound bearing an N-(thien-2-ylcarbonyl) moiety showed broad-spectrum activity with 50% growth inhibition (GI50) values in the range of 2.02-7.82 μM over 50 cell lines.

GRAPHICAL ABSTRACT

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Synthesis and antibacterial activity of novel 4-chloro-2-mercaptobenzenesulfonamide derivatives

Few series of novel 4-chloro-2-mercaptobenzenesulfonamides have been synthesized by the reactions of N-(benzenesulfonyl)cyanamide potassium salts 7-15 with corresponding hydrazinecarbodithioic acid esters, 1-substituted carbothioic acid hydrazides, methyl 3-aminothiophene-2-carboxylate, methyl 2-aminobenzoate, 2-aminophenol or 2-aminothiophenol. The synthesized compounds (16-49) were screened in vitro for their antibacterial activity. Some of the tested compounds 16, 17, 23, 24, 31, 32 and 48 showed the promising activity against many of anaerobic Gram-positive bacteria strains.

Synthesis and in vitro anticancer evaluation of some novel hexahydroquinoline derivatives having a benzenesulfonamide moiety

Inhibition of carbonic anhydrase isozymes has been found to have a role in the treatment of cancer. Several sulfonamide compounds bearing an aromatic or a heteroaromatic ring were found to posses potent carbonic anhydrase inhibitory activity and so can be used in the treatment of several types of cancer. In this paper, we present the synthesis of some novel quinoline 7-13, 21-26, 28 and pyrimidoquinoline 14-18, 20, 27 derivatives having a sulfonamide moiety. All the newly synthesized compounds were evaluated for their in vitro anticancer activity. Several compounds showed interesting cytotoxic activities when compared with the used reference drug. In addition, docking of the synthesized compounds into carbonic anhydrase isozyme II (CA II) active site was performed in order to give a suggestion about the proposed mechanism of action.

Carbonic anhydrase IX: a new druggable target for the design of antitumor agents

Carbonic anhydrases (CAs, EC 4.2.1.1) are a family of enzymes widespread in all life kingdoms. In mammals, isozyme CA IX is highly overexpressed in many cancer types being present in few normal tissues. Its expression is strongly induced by hypoxia present in many tumors, being regulated by the HIF transcription factor and correlated with a poor response to classical chemo- and radiotherapies. CA IX was recently shown to contribute to acidification of the tumor environment, by efficiently catalyzing the hydration of carbon dioxide to bicarbonate and protons with its extracellularly situated active site, leading both to the acquisition of metastasic phenotypes and to chemoresistance with weakly basic anticancer drugs. Inhibition of this enzymatic activity by specific and potent inhibitors was shown to revert these acidification processes, establishing a clear-cut role of CA IX in tumorigenesis. The development of a wide range of potent and selective CA IX inhibitors belonging to diverse chemical classes, such as membrane-impermeant, fluorescent or metal-containing such agents, could thus provide useful tools for highlighting the exact role of CA IX in hypoxic cancers, to control the pH (im)balance of tumor cells, and to develop novel diagnostic or therapeutic applications for the management of tumors. Indeed, both fluorescent inhibitors or positively charged, membrane impermeant sulfonamides have been recently developed as potent CA IX inhibitors and used as proof-of-concept tools for demonstrating that CA IX constitutes a novel and interesting target for the anticancer drug development.

Carbonic anhydrases: novel therapeutic applications for inhibitors and activators

Carbonic anhydrases (CAs), a group of ubiquitously expressed metalloenzymes, are involved in numerous physiological and pathological processes, including gluconeogenesis, lipogenesis, ureagenesis, tumorigenicity and the growth and virulence of various pathogens. In addition to the established role of CA inhibitors (CAIs) as diuretics and antiglaucoma drugs, it has recently emerged that CAIs could have potential as novel anti-obesity, anticancer and anti-infective drugs. Furthermore, recent studies suggest that CA activation may provide a novel therapy for Alzheimer's disease. This article discusses the biological rationale for the novel uses of inhibitors or activators of CA activity in multiple diseases, and highlights progress in the development of specific modulators of the relevant CA isoforms, some of which are now being evaluated in clinical trials.

Synthesis of novel 3-amino-2-(4-chloro-2-mercaptobenzenesulfonyl)-guanidine derivatives as potential antitumor agents

Novel 3-amino-2-(4-chloro-2-mercaptobenzenesulfonyl)guanidine derivatives have been synthesized as potential anticancer agents. The in vitro antitumor activity of these compounds has been evaluated in the US National Cancer Institute (NCI), and relationships between structure and antitumor activity are discussed. The prominent compound was 1-allyl-2-[4-chloro-5-(4-chlorophenylcarbamoyl)-2-methylthiobenzenesulfonyl]-3-(5-nitrofurfurylideneamino)guanidine (8) with remarkable activity against 21 human tumor cell lines representing leukemia, lung, colon, melanoma, ovarian, renal, prostate and breast (GI(50)=0.3-3.0microM), and selectivity toward leukemia RPMI-8226 cell line (GI(50)=0.3microM, TGI=1.4microM).