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Introduction The hypoxic tumor microenvironment represents a persistent obstacle in the treatment of most solid tumors. In the past years, significant efforts have been made to improve the efficacy of anti-cancer drugs. Therefore, hypoxia-activated prodrugs (HAPs) of chemotherapeutic compounds have attracted widespread interest as a therapeutic means to treat hypoxic tumors. Areas covered This updated review paper covers key patents published between 2006 and 2021 on the developments of HAP derivatives of anti-cancer compounds. Expert opinion Despite significant achievements in the development of HAP derivatives of anti-cancer compounds and although many clinical trials have been performed or are ongoing both as monotherapies and as part of combination therapies, there has currently no HAP anti-cancer agent been commercialized into the market. Unsuccessful clinical translation is partly due to the lack of patient stratification based on reliable biomarkers that are predictive of a positive response to hypoxia-targeted therapy.

In this work, two classes of Carbonic Anhydrase (CA) inhibitors, sulfonamide and coumarin derivatives linked to pyta moiety (2a-b) and their corresponding rhenium complexes (3a-b), were designed. These compounds were synthesized and fully characterized by classical analytical methods and X-ray diffraction. All the synthesized compounds were evaluated for their inhibitory activity against the hCA isoforms I, II, IX and XII. They exhibited high inhibitory activities in the range of nanomolar for both hCA IX and hCA XII isoforms. The sulfonamide compound 2a showed the strongest inhibition against the tumour-associated hCA IX isoform with a Ki of 11.7 nM. The tumour-associated isoforms hCA IX and hCA XII were selectively inhibited by all the coumarin derivatives, with inhibition constants ranging from 12.7 nM (2b) to 44.5 nM (3b), while the hCA I and II isoforms were slightly inhibited (in the micromolar range), as expected. In terms of selectivity, compared to previously published rhenium complex-based CA inhibitors, complex 3b showed one of the highest selectivities against hCA IX and hCA XII compared to the off-target isoforms hCA I and hCA II, making it a potential anti-cancer drug candidate. Molecular docking calculations were performed to investigate the inhibition profiles of the investigated compounds at the tumour-associated hCA IX active site and to rationalize our results.

International audience; Syntheses of analogues of historical indigo and Maya blue pigments using an inquiry-based approach is presented. Derivatives of indigo were synthetized (in particular Tyrian purple) and used as vat dyes for dyeing cotton or wool fabrics or mixed with a sepiolite clay to create new hues or colors of Maya blues using a green chemistry hydrothermal microwave synthesis. The hydrothermal approach allows a very quick preparation of Maya analogue pigments (typically one hour) while illustrating a green chemistry approach. The obtained Maya pigments can have very different colors (or not) from their initial indigo derivative and furthermore undergo color change under annealing (thermochromism) or mechanical grinding (tribochromism). In particular, the Tyrian purple/sepiolite chromism allows a direct visual illustration for students of the structural changes in sepiolite host-matrix associated with its pores closure and water loss.

A series of urea/thiourea substituted benzoxaboroles was investigated for the inhibition of the three carbonic anhydrases encoded by Vibrio cholerae (VchCA alpha, VchCA beta, and VchCA gamma). In particular, benzoxaborole derivatives were here first assayed for the inhibition of a gamma-class CA, extending the panel of CA classes that benzoxaboroles efficiently target beyond alpha and beta. Inhibition profiles demonstrated that VchCA alpha was significantly more inhibited compared to VchCAy and, in turn, more efficientl gamma modulated than VchCA beta. Among the many selective benzoxaborole ligands detected against VchCA alpha over the off-target hCA II, compound 18, a p-NO2-phenylthiourea derivative, even exhibited a fully selective inhibition profile against the three VchCAs over hCA IL A comprehensive ligand/target interaction study was performed in silico for all three VchCA isoforms providing the first molecular modeling investigation with inhibitors of a gamma-class CA to the best of our knowledge. The present study reinforces the rationale behind the use of benzoxaboroles as innovative antibacterial agents with a new mechanism of action, furnishing suggestions for the rational design of new potent and selective inhibitors targeting V. cholerae CAs over human off-target ones.

International audience; The synthesis, characterization, and biological evaluation of a series of compounds incorporating two or three benzoxaborole moieties is reported. Three different synthetic strategies were used to explore within this series as much chemical space as possible, all starting from the 6-aminobenzoxaborole reagent: amide coupling, imine bond formation, and squarate coupling. Eleven new compounds were isolated in pure form, and single crystals were obtained for two of them. These compounds were then evaluated as carbonic anhydrase inhibitors against the cytosolic hCA I and II and the transmembrane hCA IV, IX, and XII isoforms. While the benzoxaborole scaffold has been recently introduced as a new chemotype for carbonic anhydrase inhibition, these new multivalent derivatives exhibited superior inhibitory activity against the tumor-associated isoform hCA IX. In particular, compared to monovalent 6-aminobenzoxaborole (K-I = 813 nM) and 6-carboxybenzoxaborole (K-I = 400 nM), derivative 2h characterized by a glutamic acid structural core and two benzoxaborole moieties was found to be more potent (K-I = 64 nM) and more selective over human hCA II.

In this work, two bidentate 2-pyridyl-1,2,3-triazole ligands (3a and 3b) containing a 4-substituted benzenesulfonamide pharmacophore prepared by classical click chemistry procedures, as well as their corresponding rhenium complexes, 4a and 4b of general formula [ReCl(CO)3(L)] (L = 3a or 3b) were prepared and fully characterised by spectroscopic methods (IR, NMR, MS, UV-Vis), elemental analysis, X-ray diffraction, and theoretical studies using DFT and TD-DFT methods. In particular, we showed that, in the solid state, the pyridine and the triazole rings of 3b adopted an uncommon cis configuration which stems from intermolecular hydrogen bonds. Preliminary assays demonstrated a promising nanomolar inhibitory activity against carbonic anhydrase isoform IX for both ligands and complexes with a strong affinity Ki of 2.8 nM for ligand 3a. More interestingly, complex 4b exhibited a pronounced selectivity against hCA IX over the off-targets hCA I and hCA II which makes this compound a promising potential anticancer drug candidate.

International audience; Carbonic anhydrases have started to emerge as new potential antibacterial targets for several pathogens. Two β-carbonic anhydrases, denominated bsCA I and bsCA II, have been isolated and characterized from the bacterial pathogen Brucella suis, the causative agent of brucellosis or Malta fever. These enzymes have been investigated in detail and a wide range of classical aromatic and heteroaromatic sulfonamides as well as carbohydrate-based compounds have been found to inhibit selectively and efficiently Brucella suis carbonic anhydrases. Inhibition of these metalloenzymes constitutes a novel approach for the potential development of new anti-Brucella agents. This review aims at discussing the recent literature on this topic.

Sulphamate and sulphamide derivatives have been largely investigated as carbonic anhydrase inhibitors (CAIs) by means of different experimental techniques. However, the structural determinants responsible for their different binding mode to the enzyme active site were not clearly defined so far. In this paper, we report the X-ray crystal structure of hCA II in complex with a sulphamate inhibitor incorporating a nitroimidazole moiety. The comparison with the structure of hCA II in complex with its sulphamide analogue revealed that the two inhibitors adopt a completely different binding mode within the hCA II active site. Starting from these results, we performed a theoretical study on sulphamate and sulphamide derivatives, demonstrating that electrostatic interactions with residues within the enzyme active site play a key role in determining their binding conformation. These findings open new perspectives in the design of effective CAIs using the sulphamate and sulphamide zinc binding groups as lead compounds., Graphical Abstract

Mycobacteria cause a variety of diseases, such as tuberculosis, leprosy, and opportunistic diseases in immunocompromised people. The treatment of these diseases is problematic, necessitating the development of novel treatment strategies. Recently, β-carbonic anhydrases (β-CAs) have emerged as potential drug targets in mycobacteria. The genomes of mycobacteria encode for three β-CAs that have been cloned and characterized from Mycobacterium tuberculosis (Mtb) and the crystal structures of two of the enzymes have been determined. Different classes of inhibitor molecules against Mtb β-CAs have subsequently been designed and have been shown to inhibit these mycobacterial enzymes in vitro. The inhibition of these centrally important mycobacterial enzymes leads to reduced growth of mycobacteria, lower virulence, and impaired biofilm formation. Thus, the inhibition of β-CAs could be a novel approach for developing drugs against the severe diseases caused by pathogenic mycobacteria. In the present article, we review the data related to in vitro and in vivo inhibition studies in the field.

A series of nitroimidazoles incorporating sulfonamide/sulfamide/sulfamate moieties were designed and synthesized as radio/chemosensitizing agent targeting the tumor-associated carbonic anhydrase (CA) isoforms IX and XII. Most of the new compounds were nanomolar inhibitors of these isoforms. Crystallographic studies on the complex of hCA II with the lead sulfamide derivative of this series clarified the binding mode of this type of inhibitors in the enzyme active site cavity. Some of the best nitroimidazole CA IX inhibitors showed significant activity in vitro by reducing hypoxia-induced extracellular acidosis in HT-29 and HeLa cell lines. In vivo testing of the lead molecule in the sulfamide series, in cotreatment with doxorubicin, demonstrated a chemosensitization of CA IX containing tumors. Such CA inhibitors, specifically targeting the tumor-associated isoforms, are candidates for novel treatment strategies against hypoxic tumors overexpressing extracellular CA isozymes. © 2013 American Chemical Society.

Background and purpose Carbonic anhydrase IX (CAIX) plays an important role in pH regulation processes critical for tumor cell growth and metastasis. We hypothesize that a dual targeting bioreductive nitroimidazole based anti-CAIX sulfamide drug (DH348) will reduce tumor growth and sensitize tumors to irradiation in a CAIX dependent manner. Material and methods The effect of the dual targeting anti-CAIX (DH348) and its single targeting control drugs on extracellular acidification and radiosensitivity was examined in HT-29 colorectal carcinoma cells. Tumor growth and time to reach 4× start volume (T4×SV) was monitored for animals receiving DH348 (10 mg/kg) combined with tumor single dose irradiation (10 Gy). Results In vitro, DH348 reduced hypoxia-induced extracellular acidosis, but did not change hypoxic radiosensitivity. In vivo, DH348 monotherapy decreased tumor growth rate and sensitized tumors to radiation (enhancement ratio 1.50) without systemic toxicity only for CAIX expressing tumors. Conclusions A newly designed nitroimidazole and sulfamide dual targeting drug reduces hypoxic extracellular acidification, slows down tumor growth at nontoxic doses and sensitizes tumors to irradiation all in a CAIX dependent manner, suggesting no “off-target” effects. Our data therefore indicate the potential utility of a dual drug approach as a new strategy for tumor-specific targeting.

A β-class carbonic anhydrase (CA, EC 4.2.1.1) from the pathogenic bacterium Francisella tularensis (FtuβCA) was cloned and purified, and the anion inhibition profile was investigated. Based on the measured kinetic parameters for the enzyme catalyzed CO2 hydration reaction (kcat of 9.8×105s-1 and a kcat/KM of 8.9×107M-1s-1), FtuβCA is a highly effective enzyme. The activity of FtuβCA was not inhibited by a range of anions that do not typically coordinate Zn(II) effectively, including perchlorate, tetrafluoroborate, and hexafluorophosphate. Surprisingly, some anions which generally complex well with many cations, including Zn(II), also did not effectively inhibit FtuβCA, e.g., fluoride, cyanide, azide, nitrite, bisulphite, sulfate, tellurate, perrhenate, perrhuthenate, and peroxydisulfate. However, the most effective inhibitors were in the range of 90-94µM (sulfamide, sulfamic acid, phenylarsonic and phenylboronic acid). N,N-Diethyldithiocarbamate (KI of 0.31mM) was a moderately potent inhibitor. As Francisella tularensis is the causative agent of tularemia, the discovery of compounds that can interfere with the life cycle of this pathogen may result in novel opportunities to fight antibiotic drug resistance.

A series of 6-substituted benzoxaboroles were investigated as inhibitors of the β-class carbonic anhydrase from three pathogenic fungi (Cryptococcus neoformans, Candida glabrata, and Malassezia globosa). Independently from the nature of the substituents on the phenyl of the urea/thiourea group, all reported derivatives showed nanomolar inhibitory activities against Can2 and CgNce103 vs micromolar inhibition against MgCA. Selectivity over human CA I and CA II was noticed. The observed structure–activity relationship trends have been rationalized by modeling study of selected compounds into the active site of Can2 and MgCA. The present letter demonstrates that benzoxaborole chemotype may offer interesting opportunities for the inhibition of β-CA from pathogenic fungi and for the development of antifungal agents with a new mechanism of action.

Targeting tumour associated carbonic anhydrase (CA, EC 4.2.1.1) isoforms IX and XII is now considered as a pertinent approach for the development of new cancer therapeutics against hypoxic tumours. In the last period, with the help of X-ray crystallography, much progress has been achieved for the drug-design of selective CA IX inhibitors, by considering the three main structural elements that govern both potency and selectivity, that is, a zinc binding group (ZBG), an organic scaffold, and one or more side chains substituting the scaffold. The use of sugar moiety in the structure of sulfonamide-based CA inhibitors (CAIs), has allowed the discovery of very potent CA IX inhibitors able to impair the growth of both primary tumors and metastases. The search for specific CA IX inhibitors by using the sugar approach has become an important research field, leading to sulfonamides, sulfamates, sulfamides and coumarins with excellent in vitro activity and relevant potency in vivo, in animal models of cancer. This paper will review the latest development in this hot topic. Fil: Winum, Jean Yves. Ecole Nationale Supérieure de Chimie de Montpellier; Francia Fil: Colinas, Pedro Alfonso. Universidad Nacional de la Plata. Facultad de Ciencias Exactas. Departamento de Quimica. Laboratorio de Estudio de Compuestos Organicos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Supuran, Claudiu T.. Universita Degli Studi Di Firenze; Italia

A series of 50 sulfamates were obtained by reacting 4-aminophenol with isocyanates followed by sulfamoylation. Most of the new compounds were nanomolar inhibitors of the tumor-associated carbonic anhydrase (CA, EC 4.2.1.1) isoforms IX and XII, whereas they inhibited less cytosolic offtarget isoforms CA I and II. Some of these sulfamates showed significant antiproliferative activity in several breast cancer cell lines, such as SKBR3, MCF10A, ZR75/1, MDA-MB-361 and MCF7, constituting interesting anticancer leads.

A panel of compounds belonging to the underexposed sulfamate class of carbonic anhydrase (CA, EC 4.2.1.1) inhibitors was generated that displayed high specificity at nanomolar levels for the tumor-associated CA IX/XII isoforms. Three of the specific CA IX/XII inhibitors showed a positive response in in vitro assays for tumor cell migration and spreading. One of them, 4-(3'-(3″,5″-dimethylphenyl)ureido)phenyl sulfamate (S4), was taken forward into the orthotopic MDA-MB-231 (breast carcinoma) model in mice. Treatment with a 10 mg/kg maintenance dosage of S4 given daily on a "5 days on, 2 days off" regimen reduced metastatic tumor burden in the lung while not affecting primary tumor growth or mouse condition. CA inhibitors of the sulfamate class specifically targeting the tumor-associated isoforms are potential candidates in antimetastatic therapy.

A series of compounds incorporating both sulfonamide and sulfamide as zinc-binding groups (ZBGs) are reported as inhibitors of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). Crystallographic studies on the complex of hCA II with the lead compound of this series, namely, 4-sulfamido-benzenesulfonamide, revealed the binding of two molecules in the enzyme active site cavity, the first one canonically coordinated to the zinc ion by means of the sulfonamide group and the second one located at the entrance of the cavity. This observation led to the design of elongated molecules incorporating these two ZBGs, separated by a linker of proper length, to allow the simultaneous binding to these different sites. The "long" inhibitors indeed showed around 10 times better enzyme inhibitory properties as compared to the shorter molecules against four physiologically relevant human (h) isoforms, hCA I, II, IX, and XII.

International audience; In the facultative intracellular pathogen Brucella suis, histidinol dehydrogenase (HDH) activity, catalyzing the last step in histidine biosynthesis, is essential for intramacrophagic replication. The inhibition of this virulence factor by substituted benzylic ketones was a proof of concept that disarming bacteria leads to inhibition of intracellular bacterial growth in macrophage infection. This work describes the design, synthesis and evaluation of 19 new potential HDH inhibitors, using a combination of classical approaches and docking studies. The IC(50)-values of these inhibitors on HDH activity were in the nanomolar range, and several of them showed a 70-100% inhibition of Brucella growth in minimal medium. One selected compound yielded a strong inhibitory effect on intracellular replication of B. suis in human macrophages at concentrations as low as 5 μM, with an overall survival of intramacrophagic bacteria reduced by a factor 10(3). Docking studies with two inhibitors showed a good fitting in the catalytic pocket and also interaction with the second lipophilic pocket binding the cofactor NAD(+). Experimental data confirmed competition between inhibitors and NAD(+) at this site. Hence, these inhibitors can be considered as promising tools in the development of novel anti-virulence drugs.

A new series of sulfonamides was synthesized by the reaction of the boroxazolidone complex of l-lysine with isothiocyanates incorporating sulfamoyl moieties and diverse organic scaffolds. The obtained thioureas have been investigated as inhibitors of four physiologically relevant human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms, hCA I, II, IX and XII. Inhibition between the low nanomolar to the micromolar range has been observed against them, with several low nanomolar and tumor-CA selective inhibitors detected. These boron-containing compounds might be useful for the management of hypoxic tumors overexpressing hCA IX/XII by means of boron neutron capture therapy, a technique not investigated so far with inhibitors of this enzyme.

JNJ-26990990 ((benzo[b]thien-3-yl)methyl)sulfamide, a sulfamide derivative structurally related to the antiepileptic drug zonisamide, was reported to be devoid of carbonic anhydrase (CA, EC 4.2.1.1) inhibitory properties. Here we report that JNJ-26990990 and its S,S-dioxide analog significantly inhibit six human (h) isoforms, hCA I, II, VII, IX, XII and XIV, involved in crucial physiological processes. Inhibition and X-ray crystallographic data for the binding of the two compounds to these enzymes show significant similarity with the zonisamide inhibitory pattern. These findings prompted us to reconsider the structural/pharmacological requirements for designing effective antiepileptics possessing zinc-binding groups of the sulfamide, sulfamate or sulfonamide type in their molecules.

// Carol Ward 1 , James Meehan 1 , Peter Mullen 2 , Claudiu Supuran 3 , J. Michael Dixon 4 , Jeremy S. Thomas 5 , Jean-Yves Winum 6 , Philippe Lambin 7 , Ludwig Dubois 7 , Nanda-Kumar Pavathaneni 6, 7 , Edward J. Jarman 1 , Lorna Renshaw 4 , InHwa Um 2 , Charlene Kay 1 , David J. Harrison 2 , Ian H. Kunkler 8 , Simon P. Langdon 1 1 Division of Pathology, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom 2 School of Medicine, University of St Andrews, North Haugh, St Andrews, United Kingdom 3 Universita degli Studi di Firenze, Polo Scientifico, Laboratorio di Chimica Bioinorganica, Sesto Fiorentino, Florence, Italy 4 Edinburgh Breast Unit, Western General Hospital, Edinburgh, United Kingdom 5 Department of Pathology, Western General Hospital, Edinburgh, United Kingdom 6 Institut des Biomolecules Max Mousseron (IBMM), UMR 5247, CNRS-UM1-UM2, Batiment de Recherche Max Mousseron, Ecole Nationale Superieure de Chimie de Montpellier, Montpellier, France 7 Department of Radiation Oncology (MaastRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Center (MUMC+), Maastricht, The Netherlands 8 Edinburgh Cancer Research Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom Correspondence to: Carol Ward, e-mail: drcward@hotmail.co.uk Keywords: carbonic anhydrase IX, breast cancer, tumour microenvironment, invasion, hypoxia Received: May 11, 2015 Accepted: June 22, 2015 Published: July 04, 2015 ABSTRACT Triple negative, resistant or metastatic disease are major factors in breast cancer mortality, warranting novel approaches. Carbonic anhydrase IX (CAIX) is implicated in survival, migration and invasion of breast cancer cells and inhibition provides an innovative therapeutic strategy. The efficacy of 5 novel ureido-substituted sulfamate CAIX inhibitors were assessed in increasingly complex breast cancer models, including cell lines in normoxia and hypoxia, 3D spheroids and an ex-vivo explant model utilizing fresh biopsy tissue from different breast cancer subtypes. CAIX expression was evaluated in a tissue microarray (TMA) of 92 paired lymph node and primary breast cancers and 2 inhibitors were appraised in vivo using MDA-MB-231 xenografts. FC11409B, FC9398A, FC9403, FC9396A and S4 decreased cell proliferation and migration and inhibited 3D spheroid invasion. S4, FC9398A and FC9403A inhibited or prevented invasion into collagen. FC9403A significantly reversed established invasion whilst FC9398A and DTP348 reduced xenograft growth. TMA analysis showed increased CAIX expression in triple negative cancers. These data establish CAIX inhibition as a relevant therapeutic goal in breast cancer, targeting the migratory, invasive, and metastatic potential of this disease. The use of biopsy tissue suggests efficacy against breast cancer subtypes, and should provide a useful tool in drug testing against invasive cancers.

Targeting proteins overexpressed in hypoxic tumors is as an important means of controlling cancer disease. One such protein is the carbonic anhydrase (CA) isoenzyme IX, which in some types of tumors is overexpressed 150-200-fold. We report here a series of sulfonamide derivatives, prepared from 2-carbohydrazido- and 4-carbohydrazido-benzenesulfonamides, which were further derivatized by reaction with aryl isocyanates or arylsulfonyl isocyanates. Several low nanomolar CA IX inhibitors were detected in this way. SAR is discussed for the diverse types of inhibitors and their affinity for different isozymes, with the aim of obtaining isozyme-specific CA IX inhibitors, with putative applications as antitumor drugs. © 2005 American Chemical Society.

International audience; We investigated a series of N-hydroxysulfamides obtained by Ferrier sulfamidoglycosylation for the inhibition of two bacterial carbonic anhydrases (CAs, EC 4.2.1.1) present in the pathogen Brucella suis. bsCA I was moderately inhibited by these compounds with inhibition constants ranging between 522 and 958 nM and no notable differences of activity between the acetylated or the corresponding deacetylated derivatives. The compounds incorporating two trans-acetates and the corresponding deprotected ones were the most effective inhibitors in the series. bsCA II was better inhibited, with inhibition constants ranging between 59.8 and 799 nM. The acetylated derivatives were generally better bsCA II inhibitors compared to the corresponding deacetylated compounds. Although these compounds were not highly isoform-selective CA inhibitors (CAIs) for the bacterial over the human CA isoforms, some of them possess inhibition profiles that make them interesting leads for obtaining better and more isoform-selective CAIs targeting bacterial enzymes.

A small series of C-glycosides containing the phenol moiety was tested for the inhibition of the β-class carbonic anhydrases (βCAs, EC 4.2.1.1) from Brucella suis. Many compounds showed activities in the micromolar or submicromolar range and excellent selectivity for pathogen CAs over human isozymes. Glycosides incorporating the 3-hydroxyphenyl moiety showed the best inhibition profile, and therefore this functionality represents lead for the development of novel anti-infectives with a new mechanism of action., Laboratorio de Estudio de Compuestos Orgánicos

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