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A small library of substituted cyclic guanidine incorporated benzothiazole-6-sulphonamides was synthesized. All obtained compounds were investigated for their inhibitory activity against the key brain-associated human carbonic anhydrase isoform hCA VII (a promising target for the treatment of neuropathic pain) and three isoforms expressed in brain and other tissues, hCA I, II, and IV. Sulphaguanidine derivatives 9a–d were inactive on the all investigated isoforms while the primary sulphonamide containing guanidines 6a–c and 7a–c were inactive towards hCA IV but displayed inhibiting properties on hCA I, II, and VII with KIs values in the low nanomolar to micromolar ranges. The results indicated that isoforms hCA II and VII were potently and selectively inhibited by these compounds, whereas the cytosolic hCA I was less sensitive to inhibition. The derivatives reported in this study might be useful for design of more potent and selective inhibitors of hCA II and VII. [ABSTRACT FROM AUTHOR]

Click chemistry reactions constitute an important and relatively new approach in the medicinal chemistry toolbox and offer substantial advantages to medicinal chemists in terms of overcoming the limitations of facile chemical synthesis, increased throughput, yields and improved quality of compound libraries. Over the last two decades, click chemistry has been widely used in different aspects of carbonic anhydrase (CA, EC 4.2.1.1) modulators drug design. This review provides an overview of the general principles and applications of click chemistry in CA-related research, including the design of selective CA inhibitors (CAIs), their applications against several diseases such as innovative anticancer and anti-infective agents, fluorescent and radiopharmaceutical probes as new theranostic agents, as well as their application in protein labelling. [ABSTRACT FROM AUTHOR]

36430343 45 Geiger N., Diesendorf V., Roll V., König E.M., Obernolte H., Sewald K., Breidenbach J., Pillaiyar T., Gütschow M., Müller C.E. Cell Type-Specific Anti-Viral Effects of Novel SARS-CoV-2 Main Protease Inhibitors. 36430304 25 Angeli A., Petrou A., Kartsev V., Lichitsky B., Komogortsev A., Capasso C., Geronikaki A., Supuran C.T. Synthesis, Biological and In Silico Studies of Griseofulvin and Usnic Acid Sulfonamide Derivatives as Fungal, Bacterial and Human Carbonic Anhydrase Inhibitors. 10.3390/ijms23084342 29 Grossmannova K., Barathova M., Belvoncikova P., Lauko V., Csaderova L., Tomka J., Dulka T., Pastorek J., Madaric J. Hypoxia Marker Carbonic Anhydrase IX Is Present in Abdominal Aortic Aneurysm Tissue and Plasma. 10.3390/ijms232113082 49 Valdovino-Navarro B.J., Dueñas S., Flores-Acosta G.I., Gasperin-Bulbarela J., Bernaldez-Sarabia J., Cabanillas-Bernal O., Cervantes-Luevano K.E., Licea-Navarro A.F. Neutralizing Ability of a Single Domain VNAR Antibody: In Vitro Neutralization of SARS-CoV-2 Variants of Concern. [Extracted from the article]

Carbonic anhydrase V (CA V), a mitochondrial enzyme, was first isolated from guinea‐pig liver and subsequently identified in mice and humans. Later, studies revealed that the mouse genome contains two mitochondrial CA sequences, named Car5A and Car5B. The CA VA enzyme is most highly expressed in the liver, whereas CA VB shows a broad tissue distribution. Car5A knockout mice demonstrated a predominant role for CA VA in ammonia detoxification, whereas the roles of CA VB in ureagenesis and gluconeogenesis were evident only in the absence of CA VA. Previous studies have suggested that CA VA is mainly involved in the provision of HCO3− for biosynthetic processes. In children, mutations in the CA5A gene led to reduced CA activity, and the enzyme was sensitive to increased temperature. The metabolic profiles of these children showed a reduced supply of HCO3− to the enzymes that take part in intermediary metabolism: carbamoylphosphate synthetase, pyruvate carboxylase, propionyl‐CoA carboxylase and 3‐methylcrotonyl‐CoA carboxylase. Although the role of CA VB is still poorly understood, a recent study reported that it plays an essential role in human Sertoli cells, which sustain spermatogenesis. Metabolic disease associated with CA VA appears to be more common than other inborn errors of metabolism and responds well to treatment with N‐carbamyl‐l‐glutamate. Therefore, early identification of hyperammonaemia will allow specific treatment with N‐carbamyl‐l‐glutamate and prevent neurological sequelae. Carbonic anhydrase VA deficiency should therefore be considered a treatable condition in the differential diagnosis of hyperammonaemia in neonates and young children. [ABSTRACT FROM AUTHOR]

The mitochondrial isoforms VA/VB of metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1) are involved in metabolic processes, such as de novo lipogenesis and fatty acid biosynthesis. We review the drug design landscape for obtaining CA VA/VB-selective/effective inhibitors, starting from the clinical observations that CA inhibitory drugs, such as the antiepileptics topiramate and zonisamide, or the diuretic acetazolamide induce a significant weight loss. The main approaches for designing such compounds consisted in drug repurposing of already known CA inhibitors (CAIs); screening of synthetic/natural products libraries both in the classical and virtual modes, and de novo drug design using the tail approach. A number of such studies allowed the identification of lead compounds diverse from sulphonamides, such as tropolones, phenols, polyphenols, flavones, glycosides, fludarabine, lenvatinib, rufinamide, etc., for which the binding mode to the enzyme is not always well understood. Classical drug design studies of sulphonamides, sulfamates and sulfamides afforded low nanomolar mitochondrial CA-selective inhibitors, but detailed antiobesity studies were poorly performed with most of them. A breakthrough in the field may be constituted by the design of hybrids incorporating CAIs and other antiobesity chemotypes. [ABSTRACT FROM AUTHOR]

Acipimox, a nicotinic acid derivative in clinical use for the treatment of hyperlipidaemia, incorporates a free carboxylic acid and an N-oxide moiety, functionalities known to interact with the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1) and inhibit its activity. Herein we report that acipimox acts as a low micromolar CA inhibitor (CAI) against most human (h) isoforms possessing catalytic activity, hCA I - XIV. By using computational techniques (docking and molecular dynamics simulations), we propose that acipimox coordinates through its carboxylate group to the zinc ion from the enzyme active site cavity, whereas the N-oxide group is hydrogen-bonded to the proton shuttle His residue in some isoforms (hCA I) or to active site Thr or Gln residues in other isoforms (hCA II, III, IV, VII, etc). As some CA isoforms are involved in lipogenesis, these data may be useful for the design of more effective CAIs with antiobesity activity. [ABSTRACT FROM AUTHOR]

Carbonic anhydrases (CAs), are metallo-enzymes implicated in several pathophysiological processes where tissue pH regulation is required. CA IX is a tumor-associated CA isoform induced by hypoxia and involved in the adaptation of tumor cells to acidosis. Indeed, several tumor-driving pathways can induce CA IX expression, and this in turn has been associated to cancer cells invasion and metastatic features as well as to induction of stem-like features, drug resistance and recurrence. After its functional and structural characterization CA IX targeting approaches have been developed to inhibit its activity in neoplastic tissues, and to date this field has seen an incredible acceleration in terms of therapeutic options and biological readouts. Small molecules inhibitors, hybrid/dual targeting drugs, targeting antibodies and adoptive (CAR-T based) cell therapy have been developed at preclinical level, whereas a sulfonamide CA IX inhibitor and an antibody entered Phase Ib/II clinical trials for the treatment and imaging of different solid tumors. Here recent advances on CA IX biology and pharmacology in cancer, and its therapeutic targeting will be discussed. [ABSTRACT FROM AUTHOR]

Human carbonic anhydrases IX (hCA IX) and XII (hCA XII) are two proteins associated with tumor formation and development. These enzymes have been largely investigated both from a biochemical and a functional point of view. However, limited data are currently available on the characterization of their post-translational modifications (PTMs) and the functional implication of these structural changes in the tumor environment. In this review, we summarize existing literature data on PTMs of hCA IX and hCA XII, such as disulphide bond formation, phosphorylation, O-/N-linked glycosylation, acetylation and ubiquitination, highlighting, when possible, their specific role in cancer pathological processes. [ABSTRACT FROM AUTHOR]

Carbonic anhydrases (CAs, EC 4.2.1.1) have been studied for decades and have been classified as a superfamily of enzymes which includes, up to date, eight gene families or classes indicated with the Greek letters α, β, γ, δ, ζ, η, θ, ι. This versatile enzyme superfamily is involved in multiple physiological processes, catalysing a fundamental reaction for all living organisms, the reversible hydration of carbon dioxide to bicarbonate and a proton. Recently, the ι-CA (LCIP63) from the diatom Thalassiosira pseudonana and a bacterial ι-CA (BteCAι) identified in the genome of Burkholderia territorii were characterised. The recombinant BteCAι was observed to act as an excellent catalyst for the physiologic reaction. Very recently, the discovery of a novel ι-CAs (COG4337) in the eukaryotic microalga Bigelowiella natans and the cyanobacterium Anabaena sp. PCC7120 has brought to light an unexpected feature for this ancient superfamily: this ι-CAs was catalytically active without a metal ion cofactor, unlike the previous reported ι-CAs as well as all known CAs investigated so far. This review reports recent investigations on ι-CAs obtained in these last three years, highlighting their peculiar features, and hypothesising that possibly this new CA family shows catalytic activity without the need of metal ions. [ABSTRACT FROM AUTHOR]

Carbonic anhydrases (CAs, EC 4.2.1.1) are enzymes involved in a multitude of diseases, and their inhibitors are in clinical use as drugs for the management of glaucoma, epilepsy, obesity, and tumours. In the last decade, multitargeting approaches have been proposed by hybridisation of CA inhibitors (CAIs) of sulphonamide, coumarin, and sulphocoumarin types with NO donors, CO donors, prostaglandin analogs, β-adrenergic blockers, non-steroidal anti-inflammatory drugs, and a variety of anticancer agents (cytotoxic drugs, kinase/telomerase inhibitors, P-gp and thioredoxin inhibitors). Many of the obtained hybrids showed enhanced efficacy compared to the parent drugs, making multitargeting an effective and innovative approach for various pharmacological applications. [ABSTRACT FROM AUTHOR]

The non-nucleoside reverse transcriptase inhibitor VM1500A is approved for the treatment of HIV/AIDS in its N-acyl sulphonamide prodrug form elsulfavirine (Elpida®). Biochemical profiling against twelve human carbonic anhydrase (CA, EC 4.2.1.1) isoforms showed that while elsulfavirine was a weak inhibitor of all isoforms, VM1500A potently and selectively inhibited human (h) hCA VII isoform, a proven target for the therapy of neuropathic pain. The latter is a common neurologic complication of HIV infection and we hypothesise that by using Elpida® in patients may help alleviate this debilitating symptom. [ABSTRACT FROM AUTHOR]

Inhibition of carbonic anhydrase (CA, EC 4.2.1.1) was clinically exploited for decades, as most modern diuretics were obtained considering as lead molecule acetazolamide, the prototypical CA inhibitor (CAI). The discovery and characterization of multiple human CA (hCA) isoforms, 15 of which being known today, led to new applications of their inhibitors. They include widely clinically used antiglaucoma, antiepileptic and antiobesity agents, antitumor drugs in clinical development, as well as drugs for the management of acute mountain sickness and idiopathic intracranial hypertension (IIH). Emerging roles of several CA isoforms in areas not generally connected to these enzymes were recently documented, such as in neuropathic pain, cerebral ischemia, rheumatoid arthritis, oxidative stress and Alzheimer's disease. Proof-of-concept studies thus emerged by using isoform-selective inhibitors, which may lead to new clinical applications in such areas. Relevant preclinical models are available for these pathologies due to the availability of isoform-selective CAIs for all human isoforms, belonging to novel classes of compounds, such as coumarins, sulfocoumarins, dithiocarbamates, benzoxaboroles, apart the classical sulfonamide inhibitors. The inhibition of CAs from pathogenic bacteria, fungi, protozoans or nematodes started recently to be considered for obtaining anti-infectives with a new mechanism of action. [ABSTRACT FROM AUTHOR]

Coumarins constitute a relatively new class of inhibitors of the zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1), possessing a unique inhibition mechanism, acting as "prodrug inhibitors." They undergo the hydrolysis of the lactone ring mediated by the esterase activity of CA. The formed 2-hydroxy-cinnamic acids thereafter bind within a very particular part of the enzyme active site, at its entrance, where a high variability of amino acid residues among the different mammalian CA isoforms is present, and where other inhibitors classes were not seen bound earlier. This explains why coumarins are among the most isoform-selective CA inhibitors known to date among the many chemotypes endowed with such biological activity. As coumarins are widespread secondary metabolites in some bacteria, plants, fungi, and ascidians, many such compounds from various natural sources have been investigated for their CA inhibitory properties and for possible biomedical applications, mainly as anticancer agents targeting hypoxic tumours. [ABSTRACT FROM AUTHOR]

Human carbonic anhydrases (CAs) have become a well-recognized target for the design of inhibitors and activators with biomedical applications. Accordingly, an enormous amount of literature is available on their biochemical, functional and structural aspects. Nevertheless post-translational modifications (PTMs) occurring on these enzymes and their functional implications have been poorly investigated so far. To fill this gap, in this review we have analysed all PTMs occurring on human CAs, as deriving from the search in dedicated databases, showing a widespread occurrence of modification events in this enzyme family. By combining these data with sequence alignments, inspection of 3 D structures and available literature, we have summarised the possible functional implications of these PTMs. Although in some cases a clear correlation between a specific PTM and the CA function has been highlighted, many modification events still deserve further dedicated studies. [ABSTRACT FROM AUTHOR]

Among the diagnostic techniques for the identification of tumour biomarkers, the liquid biopsy is considered one that offers future research on precision diagnosis and treatment of tumours in a non-invasive manner. The approach consists of isolating tumor-derived components, such as circulating tumour cells (CTC), tumour cell-free DNA (ctDNA), and extracellular vesicles (EVs), from the patient peripheral blood fluids. These elements constitute a source of genomic and proteomic information for cancer treatment. Within the tumour-derived components of the body fluids, the enzyme indicated with the acronym CA IX and belonging to the superfamily of carbonic anhydrases (CA, EC 4.2.1.1) is a promising aspirant for checking tumours. CA IX is a transmembrane-CA isoform that is strongly overexpressed in many cancers being not much diffused in healthy tissues except the gastrointestinal tract. Here, it is summarised the role of CA IX as tumour-associated protein and its putative relationship in liquid biopsyfor diagnosing and monitoring cancer progression. [ABSTRACT FROM AUTHOR]

Carbonic anhydrase (CA, EC 4.2.1.1) isoforms IX and XII are overexpressed in many hypoxic tumors as a consequence of the hypoxia inducible factor (HIF) activation cascade, being present in limited amounts in normal tissues. These enzymes together with many others are involved in the pH regulation and metabolism of hypoxic cancer cells, and were validated as antitumor targets recently. A multitude of targeting strategies against these enzymes have been proposed and are reviewed in this article. The small molecule inhibitors, small molecule drug conjugates (SMDCs), antibody-drug conjugates (ADACs) or cytokine-drug conjugates but not the monoclonal antibodies against CA IX/XII will be discussed. Relevant synthetic chemistry efforts, coupled with a multitude of preclinical studies, demonstrated that CA IX/XII inhibition leads to the inhibition of growth of primary tumors and metastases and depletes cancer stem cell populations, all factors highly relevant in clinical settings. One small molecule inhibitor, sulfonamide SLC-0111, is the most advanced candidate, having completed Phase I and being now in Phase Ib/II clinical trials for the treatment of advanced hypoxic solid tumors. [ABSTRACT FROM AUTHOR]

2-Mercaptobenzoxazole is a widely used organic scaffold in medicinal chemistry. By means of kinetic and structural studies, we demonstrate that this molecule can effectively be used to inhibit hCAs showing a peculiar binding mode. The results reported here can pave the way for the development of selective CA inhibitors. [ABSTRACT FROM AUTHOR]

Eight genetically distinct carbonic anhydrase (EC 4.2.1.1) enzyme families (α-, β-, γ- δ-, ζ-, η-, θ- and ι-CAs) were described to date. On the other hand, 16 mammalian α-CA isoforms are known to be involved in many diseases such as glaucoma, edema, epilepsy, obesity, hypoxic tumors, neuropathic pain, arthritis, neurodegeneration, etc. Although CA inhibitors were investigated for the management of a variety of such disorders, the activators just started to be investigated in detail for their in vivo effects. This review summarizes the activation profiles of α-, β, γ-, δ-, ζ- and η- CAs from various organisms (animals, fungi, protozoan, bacteria and archaea) with the most investigated classes of activators, the amines and the amino acids. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbonic anhydrases are involved in many physiologic and pathologic processes. • The drug design of inhibitors and activators in the last 30 years is discussed. • New inhibition/activation mechanisms were discovered. • The tail approach was the main drug design strategy for obtaining CA inhibitors: • New inhibition mechanisms apart zinc coordination and many new CAI chemotypes are available. • Human CAs are new drug targets for obesity, cancer, neuropathic pain, cerebral ischemia. • CAs from bacteria, fungi, protozoa and worms are drug targets for antiinfectives. • CA activators are involved in cognition. Advances in the carbonic anhydrase (CA, EC 4.2.1.1) research over the last three decades are presented, with an emphasis on the deciphering of the activation mechanism, the development of isoform-selective inhibitors/ activators by the tail approach and their applications in the management of obesity, hypoxic tumors, neurological conditions, and as antiinfectives. [ABSTRACT FROM AUTHOR]

A set of compounds incorporating carbon-based zinc-binding groups (ZBGs), of the type PhX (X = COOH, CONH2, CONHNH2, CONHOH, CONHOMe), and the corresponding derivatives with sulphur(VI)-based ZBGs (X = SO3H, SO2NH2, SO2NHNH2, SO2NHOH, SO2NHOMe) were tested as inhibitors of all mammalian isoforms of carbonic anhydrase (CA, EC 4.2.1.1), CA I-XV. Three factors connected with the ZBG influenced the efficacy as CA inhibitor (CAI) of the investigated compounds: (i) the pKa of the ZBG; (ii) its geometry (tetrahedral, i.e. sulphur-based, versus trigonal, i.e. carbon-based ZBGs), and (iii) orientation of the organic scaffold induced by the nature of the ZBG. Benzenesulphonamide was the best inhibitor of all isoforms, but other ZBGs led to interesting inhibition profiles, although with an efficacy generally reduced when compared to the sulphonamide. The nature of the ZBG also influenced the CA inhibition mechanism. Most of these derivatives were zinc binders, but some of them (sulfonates, carboxylates) may interact with the enzyme by anchoring to the zinc-coordinated water molecule or by other inhibition mechanisms (occlusion of the active site entrance, out of the active site binding, etc.). Exploring structurally diverse ZBGs may lead to interesting new developments in the field of CAIs. [ABSTRACT FROM AUTHOR]

Natural products and analogues are a source of antibacterial drug discovery. Considering drug resistance levels emerging for antibiotics, identification of bacterial metalloenzymes and the synthesis of selective inhibitors are interesting for antibacterial agent development. Peptide nucleic acids are attractive antisense and antigene agents representing a novel strategy to target pathogens due to their unique mechanism of action. Antisense inhibition and development of antisense peptide nucleic acids is a new approach to antibacterial agents. Due to the increased resistance of biofilms to antibiotics, alternative therapeutic options are necessary. To develop antimicrobial strategies, optimised in vitro and in vivo models are needed. In vivo models to study biofilm-related respiratory infections, device-related infections: ventilator-associated pneumonia, tissue-related infections: chronic infection models based on alginate or agar beads, methods to battle biofilm-related infections are discussed. Drug delivery in case of antibacterials often is a serious issue therefore this review includes overview of drug delivery nanosystems. [ABSTRACT FROM AUTHOR]

A library of novel alkyl/benzyl (4-sulphamoylphenyl)carbamimidothioates was synthesised by selective S-alkylation of the easily accessible 4-thioureidobenzenesulphonamide. The compounds were assayed as inhibitors of four human (h) carbonic anhydrase isoforms hCA I, II, VII, and XIII, as well as three bacterial enzymes belonging to the β-CA class, MscCA from Mammaliicoccus (Staphylococcus) sciuri and StCA1 and StCA2, from Salmonella enterica (serovar Typhimurium). Most compounds investigated here exhibited moderate to low nanomolar inhibition constants against hCA I, II, and VII. The cytosolic hCA XIII was also inhibited by these compounds, but not as effective as hCA I, II, and VII. Several compounds were very effective against MscCA and StCA1. StCA2 was less inhibited compared to MscCA and StCA1. Some compounds showed considerable selectivity for inhibiting some CA isoforms. They may thus be considered as interesting starting points for the discovery and development of novel therapeutic agents belonging to this class of enzyme inhibitors. [ABSTRACT FROM AUTHOR]

A one-pot two-step protocol was developed for the synthesis of a series of novel 4-cyanamidobenzenesulfonamides from easily accessible methyl (4-sulfamoylphenyl)-carbamimidothioate. The new sulphonamides were investigated as inhibitors of the enzyme carbonic anhydrase (CA, EC 4.2.1.1), the human (h) cytosolic isoforms hCA I, II, VII, and XIII, as well as three bacterial enzymes belonging to the β-CA class, MscCA from Mammaliicoccus (Staphylococcus) sciuri and StCA1 and StCA2, from Salmonella enterica (serovar Typhimurium). The human isoforms were generally effectively inhibited by these compounds, with a clear structure-activity relationship privileging long aliphatic chains (C6, C7 and C18) as substituents at the cyanamide functionality. The bacterial CAs were also inhibited by these compounds, but not as effective as the hCAs. The most sensitive enzyme to these inhibitors was StCA1 (KIs of 50.7 − 91.1 nM) whereas SscCA was inhibited in the micromolar range (KIs of 0.86–9.59 µM). [ABSTRACT FROM AUTHOR]

We investigated the carbonic anhydrase (CA, EC 4.2.1.1) inhibitory activity of the clinically used antitumor agent bortezomib, a marketed proteasome inhibitor, against all the catalytically active mammalian isoforms CA I–VII, IX, XII–XV. Bortezomib effectively inhibited all these CAs in the micromolar range. hCA II, the physiologically dominant cytosolic isoform showed the highest affinity for the drug, with a K I of 1.16 μM. The cytosolic slow isoform hCA I was also effectively inhibited, with a K I of 1.29 μM, whereas the next best affinity was observed for the membrane-anchored form mCA XV, with a K I of 2.68 μM, followed by two transmembrane isoforms, hCA IX and XIV ( K I s of 3.28–3.38 μM). The remaining cytosolic (CA III, VII and XIII), membrane-anchored (CA IV), mitochondrial (CA VA, VB), transmembrane (CA XII) and secreted (CA VI) isoforms were slightly less inhibited by bortezomib compared to isoforms discussed above, with K I s ranging between 4.38 and 8.45 μM. These data may shed some light on possible side effects and novel antitumor mechanisms of action of this drug. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various reports within the issue on topics including N-pyrrylarylsulfones, a class of pharmacological agents, carbonic anhydrases (CAs) from various organisms, and benzenesulfamide derivatives.

Integration of a desossiribonucleic acid (DNA) copy of the viral ribonucleic acid (RNA) into host genomes is a fundamental step in the replication cycle of all retroviruses. The highly conserved virus-encoded Integrase enzyme (IN; EC 2.7.7.49) catalyzes such a process by means of two consecutive reactions named 3′-processing (3-P) and strand transfer (ST). The Authors report and discuss the major discoveries and advances which mainly contributed to the development of Human Immunodeficiency Virus (HIV) -IN targeted inhibitors for therapeutic applications. All the knowledge accumulated over the years continues to serve as a valuable resource for the design and development of effective antiretroviral drugs. [ABSTRACT FROM AUTHOR]

Carbonic anhydrase inhibitors (CAIs) are of growing interest since various isoforms of the enzyme are identified as promising drug targets for treatment of disease. The principal drawback of the clinically used CAIs is the lack of isoform selectivity, which may lead to observable side effects. Studies aiming at the design of isoform-selective CAIs entail generation and biological testing of arrays of compounds, which is a resource- and time-consuming process. Employment of multicomponent reactions is an efficient synthetic strategy in terms of gaining convenient and speedy access to a range of scaffolds with a high degree of molecular diversity. However, this powerful tool appears to be underutilized for the discovery of novel CAIs. A number of studies employing multicomponent reactions in CAI synthesis have been reported in literature. Some of these reports provide inspiring examples of successful use of multicomponent chemistry to construct novel potent and often isoform-selective inhibitors. On critical reading of several publications, however, it becomes apparent that for some chemical series designed as CAIs, the desired inhibitory properties are only assumed and never tested for. In these cases, the biological profile is reported based on the results of phenotypical cellular assays, with no correlation with the intended on-target activity. Present review aims at critically assessing the current literature on the multicomponent chemistry in the CAI design. [ABSTRACT FROM PUBLISHER]

Natural products represent a straightforward source for molecular structures bearing a vast array of chemical features and potentially useful for biomedical purposes. Recent examples of this type include the discovery of the coumarins and the polyamine natural products as atypical chemotypes for the inhibition of the metalloenzymes carbonic anhydrases (CAs; EC 4.2.2.1). CA enzymes are established pharmacological targets for important pathologies, which, among others, include glaucoma, hypoxic tumors, and central nervous system (CNS)-affecting diseases. Moreover, they are expressed in many bacteria, fungi and helminths which are the etiological agents of the majority of infectious diseases. In this context, natural products represent the ideal source of new and selective druggable CA modulators for biomedical purposes. Herein we report the state of the art on polyamines of natural origin as well as of synthetic derivatives as inhibitors of human CAs. [ABSTRACT FROM AUTHOR]

A series of novel benzene sulfonamides (previously evaluated as selective cyclooxygenase-2 inhibitors) has been profiled against human carbonic anhydrases I, II, IV and VII in an attempt to observe the manifestation of the well established “tail” approach for designing potent, isoform-selective inhibitors of carbonic anhydrases (CAs, EC 4.2.1.1). The compounds displayed an excellent (pKi 7–8) inhibitory profile against CA II (a cytosolic anti-glaucoma and anti-edema biological target) and CA VII (also a cytosolic target believed to be involved in epilepsy and neuropathic pain) and a marked (1–2 orders of magnitude) selectivity against cytosolic isoform CA I and membrane-bound isoform CA IV. The separation of the CA II and CA IV (both of which are catalytically active isoforms, highly sensitive to sulfonamide-type inhibitors) is particularly remarkable and is adding significantly to the global body of data on the chemical biology of carbonic anhydrases. [ABSTRACT FROM AUTHOR]

Among protein families, carbonic anhydrases (CAs, EC 4.2.1.1) are metalloenzymes characterized by a common reaction mechanism in all life domains: the carbon dioxide hydration to bicarbonate and protons (CO2+H2O ⇔ HCO3−+H+). Six genetically distinct CA families are known to date, the α-, β-, γ-, δ-, ζ- and η-CAs. The last CA class was recently discovered analyzing the amino acid sequences of CAs from Plasmodia. Bacteria encode for enzymes belonging to the α-, β-, and γ-CA classes and recently, phylogenetic analysis revealed an interesting relationship regarding the evolution of bacterial CA classes. This result evidenced that the three bacterial CA classes, in spite of the high level of the structural similarity, are evolutionarily distinct, but we noted that the primary structure of some β-CAs identified in the genome of Gram-negative bacteria present a pre-sequence of 18 or more amino acid residues at theN-terminal part. These observations and subsequent phylogenetic data presented here prompted us to propose that the β-CAs found in Gram-negative bacteria with a periplasmic space and characterized by the presence of a signal peptide might have a periplasmic localization and a role similar to that described previously for the α-CAs. [ABSTRACT FROM PUBLISHER]

Inhibition of the β-carbonic anhydrases (CAs, EC 4.2.1.1) from pathogenic fungi ( Cryptococcus neoformans , Candida albicans , Candida glabrata , Malassezia globosa ) and bacteria (three isoforms from Mycobacterium tuberculosis , Rv3273, Rv1284 and Rv3588), as well from the insect Drosophila melanogaster (DmeCA) and the plant Flaveria bidentis (FbiCA1) with the boronic acid peptidomimetic proteosome inhibitor bortezomib was investigated. Bortezomib was a micromolar inhibitor of all these enzymes, with K I s ranging between 1.12 and 11.30 μM. Based on recent crystallographic data it is hypothesized that the B(OH) 2 moiety of the inhibitor is directly coordinated to the zinc ion from the enzyme active site. The class of boronic acids, an under-investigated type of CA inhibitors, may lead to the development of anti-infectives with a novel mechanism of action, based on the pathogenic organisms CA inhibition. [ABSTRACT FROM AUTHOR]

Herein we report an in vitro kinetic evaluation against the most relevant human carbonic anhydrase (hCA, EC 4.2.1.1) isoforms (I, II, IX and XII) of a small series of lactate dehydrogenase (LDH, EC 1.1.1.27) inhibitors. All compounds contain a primary sulfonamide zinc-binding group (ZBG) substituted with the 2-thio-6-oxo-1,6-dihydropyrimidine scaffold. By means of X-ray crystallographic experiments we explored the ligand–enzyme binding modes, thus highlighting the contribution of the 2-thio-6-oxo-1,6-dihydropyrimidine moiety to the stabilization of the complex. [ABSTRACT FROM AUTHOR]

Carbonic anhydrase (CA, EC 4.2.1.1) inhibitors (CAIs) started to be used in the treatment of peptic ulcers in the 1970s, and for more than two decades, a group led byIoan Puşcaşused them for this purpose, assuming that by inhibiting the gastric mucosa CA isoforms, hydrochloric acid secretion is decreased. Although acetazolamide and other sulfonamide CAIs are indeed effective in healing ulcers, the inhibition of CA isoforms in other organs than the stomach led to a number of serious side effects which made this treatment obsolete when the histamine H2 receptor antagonists and the proton pump inhibitors became available. Decades later, in 2002, it has been discovered thatHelicobacter pylori, the bacterial pathogen responsible for gastric ulcers and cancers, encodes for two CAs, one belonging to the α-class and the other one to the β-class of these enzymes. These enzymes are crucial for the life cycle of the bacterium and its acclimation within the highly acidic environment of the stomach. Inhibition of the two bacterial CAs with sulfonamides such as acetazolamide, a low-nanomolarH. pyloriCAI, is lethal for the pathogen, which explains why these compounds were clinically efficient as anti-ulcer drugs. Thus, the approach promoted byIoan Puşcaşfor treating this disease was a good one although the rationale behind it was wrong. In this review, we present a historical overview of the sulfonamide CAIs as anti-ulcer agents, in memoriam of the scientist who was in the first line of this research trend. [ABSTRACT FROM AUTHOR]

Carbonic anhydrases (CAs, EC 4.2.1.1) catalyse the interconversion between CO2 and bicarbonate as well as other hydrolytic reactions. Among the six genetic families known to date, the α-, β-, γ -, δ-, ζ- and η-CAs, detailed kinetic and X-ray crystallographic studies have allowed a deep understanding of the structure–function relationship in this superfamily of proteins. A metal hydroxide nucleophilic species of the enzyme, and a unique active site architecture, with half of it hydrophilic and the opposing part hydrophobic, allow these enzymes to act as some of the most effective catalysts known in Nature. The CA activation and inhibition mechanisms are also known in detail, with a large number of new inhibitor classes being described in the last years. Apart from the zinc binders, some classes of inhibitors anchor to the metal ion coordinated nucleophile, others occlude the entrance of the active site cavity and more recently, compounds binding outside the active site were described. CA inhibition has therapeutic applications for drugs acting as diuretics, antiepileptics, antiglaucoma, antiobesity and antitumour agents. Targeting such enzymes from pathogens may lead to novel anti-infectives. Successful structure-based drug design campaigns allowed the discovery of highly isoform selective CA inhibitors (CAIs), which may lead to a new generation of drugs targeting these widespread enzymes. The use of CAs in CO2 capture processes for mitigating the global temperature rise has also been investigated more recently. Key words: carbonic anhydrase, CO2 capture, drug, enzyme inhibitor, metalloenzyme, X-ray crystallography. [ABSTRACT FROM AUTHOR]

Specific isoforms from the carbonic anhydrase (CA) family of zinc metalloenzymes have been associated with a variety of diseases. Isoform-specific carbonic anhydrase inhibitors (CAIs) are therefore a major focus of attention for specific disease treatments. Classical CAIs, primarily sulfonamide-based compounds and their bioisosteres, are examined as antiglaucoma, antiepileptic, antiobesity, antineuropathic pain and anticancer compounds. However, many sulfonamide compounds inhibit all CA isoforms nonspecifically, diluting drug effectiveness and causing undesired side effects due to off-target inhibition. In addition, a small but significant percentage of the general population cannot be treated with sulfonamide-based compounds due to a sulfa allergy. Therefore, CAIs must be developed that are not only isoform specific, but also non-classical, i.e. not based on sulfonamides, sulfamates, or sulfamides. This review covers the classes of non-classical CAIs and the recent advances in the development of isoform-specific inhibitors based on phenols, polyamines, coumarins and their derivatives. [ABSTRACT FROM AUTHOR]

Six genetic families of the enzyme carbonic anhydrase (CA, EC 4.2.1.1) were described to date. Inhibition of CAs has pharmacologic applications in the field of antiglaucoma, anticonvulsant, anticancer, and anti-infective agents. New classes of CA inhibitors (CAIs) were described in the last decade with enzyme inhibition mechanisms differing considerably from the classical inhibitors of the sulfonamide or anion type. Five different CA inhibition mechanisms are known: (i) the zinc binders coordinate to the catalytically crucial Zn(II) ion from the enzyme active site, with the metal in tetrahedral or trigonal bipyramidal geometries. Sulfonamides and their isosters, most anions, dithiocarbamates and their isosters, carboxylates, and hydroxamates bind in this way; (ii) inhibitors that anchor to the zinc-coordinated water molecule/hydroxide ion (phenols, carboxylates, polyamines, 2-thioxocoumarins, sulfocoumarins); (iii) inhibitors which occlude the entrance to the active site cavity (coumarins and their isosters), this binding site coinciding with that where CA activators bind; (iv) compounds which bind out of the active site cavity (a carboxylic acid derivative was seen to inhibit CA in this manner), and (v) compounds for which the inhibition mechanism is not known, among which the secondary/tertiary sulfonamides as well as imatinib/nilotinib are the most investigated examples. As CAIs are used clinically in many pathologies, with a sulfonamide inhibitor (SLC-0111) in Phase I clinical trials for the management of metastatic solid tumors, this review updates the recent findings in the field which may be useful for a structure-based drug design approach of more selective/potent modulators of the activity of these enzymes. [ABSTRACT FROM AUTHOR]

A quantitative structure–activity relationship (QSAR) study of sulfonamide inhibitors targeting the β-carbonic anhydrase (CA, EC 4.2.1.1) from the fungusMalassezia globosais reported. A large set of PRECLAV descriptors has been used to obtain four parametric models. This study presents QSAR data on a pool of 28 compounds. The quality of prediction is high enough (SE = 0.3446,r2 = 0.8687,F = 39.6921,Q = 0.7446). A heuristic algorithm selected the best multiple linear regression (MLR) equation which showed the correlation between the observed values and the calculated values of activity. The proposed prediction set included new, not yet synthesized, 23 molecules having various structures. Many compounds in the prediction set seem to possess higher computed activity compared to the presently availableM. globosaβ-CA inhibitors. [ABSTRACT FROM AUTHOR]

Carbonic anhydrases (CAs, EC 4.2.1.1) are metalloenzymes which catalyze a simple but physiologically crucial reaction in all life Domains, the carbon dioxide hydration to bicarbonate and protons: CO2 + H2O ⇔ + H+. These enzymes are involved in many physiologic processes, such as photosynthesis, respiration, CO2 transport, as well as metabolism of xenobiotics. Five different, genetically distinct CA families are known to date: the α-, β-, γ-, δ- and ζ-CAs. α-, β- and δ-CAs use Zn(II) ions at the active site, the γ-CAs are probably Fe(II) enzymes (but they are active also with bound Zn(II) or Co(II) ions), whereas the ζ-class uses Cd(II) or Zn(II) to perform the physiologic reaction catalysis. Bacteria encode for enzymes belonging to the α-, β-, and γ-CA classes. They contain zinc ion (Zn2+) in their active site, coordinated by three histidine residues and a water molecule/hydroxide ion (in the α and γ) or by two cysteine and one histidine residues (in the β class), with the fourth ligand being a water molecule/hydroxide ion. Here we propose that bacterial CAs can be used as markers for understanding the evolution and genetic variability of the Gram-positive and Gram-negative bacteria. We addressed several questions such as: (1) why are α-CAs present only in the genome of Gram-negative bacteria; (2) why are α-CAs not present in all Gram-negative bacteria; (3) why do Bacteria show an intricate pattern of CA gene expression; (4) what are the physiologic roles of such diverse CAs in these prokaryotes. We proposed possible answers to the previous questions. Moreover, we speculated on the evolution of the CA classes (α, β and γ) identified in the Gram-negative and -positive bacteria. Our main hypothesis is that from the ancestral Ur-CA, the γ-class arose first, followed by the β-class; the α-class CAs came last it is found only in the Gram-negative bacteria. [ABSTRACT FROM AUTHOR]

In addition to the sulfonamides and their isosteres, recently novel carbonic anhydrase (CA, EC 4.2.1.1) inhibitors (CAIs) which act by binding to the metal ion from the active site were discovered. Based on the X-ray crystal structure of the CA II-trithiocarbonate adduct, dithiocarbamates, xanthates and thioxanthates were shown to potently inhibit α- and β-CAs. The hydroxamates constitute another class of recently studied CAIs both against mammalian and protozoan enzymes. Another chemotype for which CA inhibitory properties were recently reported is the salicylaldoxime scaffold. X-ray crystal structures were reported for CA II complexed with dithiocarbamates and hydroxamates, whereas the xanthates and salicylaldoximes were investigated by kinetic measurements and docking studies. The dithiocarbamates and the xanthates showed potent antiglaucoma activity in animal models of the disease whereas some hydroxamates inhibited the growth of Trypanosoma cruzii probably by inhibiting the protozoan CA. [ABSTRACT FROM AUTHOR]

Ureido-substituted benzene sulfonamides are the most important class of CA inhibitors which significantly inhibited the formation of primary tumors and metastases. Here, we present quantitative structure activity relationships (QSAR) study on a pool of 27 such inhibitors. A heuristic algorithm selected the best multiple linear regression (MLR) equation, showing the correlation between the observed values and the calculated values of activity. The calculated values of activity were in good agreement with the experimental values. The novelty of this work consists in not only exploring the structural attributes of bioactive molecules but also in predicting in silico the structures of new compounds which may show antimetastatic activity. The not yet synthesized such molecules (i.e. the prediction set) included many compounds showing a higher computed activity compared to the reported such derivatives, but they have been however not yet assayed. [ABSTRACT FROM AUTHOR]

The development of heterocyclic derivatives has progressed considerably over the past decades, and many new carbonic anhydrase inhibitors (CAIs) fall into this field. In particular, five-membered heterocyclic sulfonamides have been generally shown to be more effective inhibitors compared to six-membered rings ones. Despite the importance of oxygen and nitrogen five-membered heterocyclic aromatic rings in medicinal chemistry, the installation of sulfonamide moiety on such heterocycles has not received much attention. On the other hand, 1,3,4-thiadiazole/thiadiazoline ring-bearing sulfonamides are the scaffolds which have been widely used in a variety of pharmaceutically important CAIs such as acetazolamide, metazolamide and their many derivatives obtained by using the tail approach. Here, we reviewed the field focusing on the diverse biological activities of these CAIs, such as antiglaucoma, antiepileptic, antitumor and antiinfective properties. This review highlights developments involving five-membered heterocyclic sulfonamides over the last years, with a focus on their pharmacological/clinical applications. [ABSTRACT FROM AUTHOR]

The human pathogen Mycobacterium tuberculosis contains three β-carbonic anhydrases (CAs, EC 4.2.1.1) in its genome. Inhibition of some of these CAs was shown to modulate the growth of M. tuberculosis. 3D-QSAR Comparative molecular field analyses (CoMFA) were carried out on inhibitors of the enzyme Rv3588c (also denominated mtCA 2). A series of sulfonamides known to inhibit mtCA 2, including some diazenylbenzenesulfonamides, was considered in our study. The predictive ability of the model was assessed using a test set of seven compounds. The best model has demonstrated a good fit having predictive r2 value of 0.93 and cross-validated coefficient q2 value as 0.88 in tripos CoMFA region. Our results indicate that the steric and electrostatic factors play a significant role in mtCA 2 inhibition for the investigated compounds. We proposed nine new not yet synthesized mtCA 2 inhibitors, all of them probably with significantly improved anti-Rv3588c inhibitory activity. [ABSTRACT FROM AUTHOR]

Recent advances in microbial genomics, synthetic organic chemistry and X-ray crystallography provided opportunities to identify novel antibacterial targets for the development of new classes of antibiotics and to design more potent antimicrobial compounds derived from existing antibiotics in clinical use for decades. The antimetabolites, sulfa drugs and trimethoprim (TMP)-like agents, are inhibitors of three families of enzymes. One family belongs to the carbonic anhydrases, which catalyze a simple but physiologically relevant reaction in all life kingdoms, carbon dioxide hydration to bicarbonate and protons. The other two enzyme families are involved in the synthesis of tetrahydrofolate (THF), i.e. dihydropteroate synthase (DHPS) and dihydrofolate reductase. The antibacterial agents belonging to the THF and DHPS inhibitors were developed decades ago and present significant bacterial resistance problems. However, the molecular mechanisms of drug resistance both to sulfa drugs and TMP-like inhibitors were understood in detail only recently, when several X-ray crystal structures of such enzymes in complex with their inhibitors were reported. Here, we revue the state of the art in the field of antibacterials based on inhibitors of these three enzyme families. [ABSTRACT FROM AUTHOR]

Abstract: The last version of the PRECLAV algorithm was used to investigate a series of sulfamate/sulfamide carbonic anhydrase (CA, EC 4.2.1.1) inhibitors. PRECLAV allows identification of outliers for lead hopping, significant molecular fragments and similarity computation of a calibration set vs. a prediction set of compounds, from the viewpoint of computed QSAR. In the current study the database included 65 sulfamates and sulfamides as calibration set and 51 not yet synthesized sulfamates and sulfamides as prediction set. The dependent property was inhibitory activity for human (h) CA isozymes I, II, IX and XII. There were no outliers for lead hopping in the calibration set. In some cases, replacing of the O–SO2–NH2 by the NH–SO2–NH2 moiety, led to modifications in the structure of molecular fragments in another regions of the molecule. According to the descriptors in the obtained models, the inhibition of all CA isozymes was strongly influenced by the molecular shape and size of the sulfamates/sulfamides (which incorporate a substituted aryl-ureido scaffold). The lipophilicity of the inhibitors seemed to be a minor factor influencing CA inhibitory action. The presence of specific PRECLAV molecular fragments such as a C6 (totally substituted benzene), F, O and NO2 increases the activity of inhibitors against certain isoforms. The presence of molecular fragments such as C, CH, CxHy (substituted benzene/naphthalene) and NH decreased the activity of inhibitors against certain isoforms. In the prediction set, we evidenced seven compounds estimated to be highly active inhibitors for at least three of the investigated isozymes and eight molecules estimated to possess low activity against at least three CAs. The paper suggests the structure of some possible interesting inhibitors incorporating F, O and NO2 fragments that may have affinity for certain human CAs. [Copyright &y& Elsevier]

Abstract: Scleractinian coral stylophora pistillata carbonic anhydrase (STPCA) enzyme is a secreted isoform, plays a direct role in bio-mineralization. Sulfonamides, including some clinically used derivatives are the most important class of STPCA inhibitors. In order to search for efficient STPCA inhibitors molecules, the present work deals with quantitative structure–activity relationship (QSAR) studies of a series of 36 bioactive molecules. A heuristic algorithm selects the best multiple linear regression (MLR) equation showed the correlation between the observed values and the calculated values of activity is very good (N =36, Se =0.1683, r 2 =0.9158, F =54.3809, =0.8569). The novelty of this work is not only to explore the structural attributes of bioactive molecules but also to design and predict in silico the STPCA inhibitory activity of new not yet synthesized compounds. The analyzed prediction set includes many molecules having greater computed activity than observed value of inhibitory activity. [Copyright &y& Elsevier]

Abstract: The parameterization of carbonic anhydrase binding site in OPLS-AA force field was performed using quantum chemistry calculations. Both OH2 and OH− forms of the binding site were considered, showing important differences in terms of atomic partial charges. Three different parameterization protocols were used, and the results obtained highlighted the importance of including an extended binding site in the charge calculation. The force field parameters were subsequently validated using standard molecular dynamics simulations. The results presented in this work should greatly facilitate the use of molecular dynamics simulations for studying the carbonic anhydrase, and more generally, the metallo-enzymes. [Copyright &y& Elsevier]

Tumoral microenvironments play a key role in the evolution of solid tumors. Tumor hypoxia is actively involved in the promotion of genetic instability, the invasive capacity of tumor cells, metastasis, and a worsening of the clinical evolution. Endogenous hypoxia markers are controlled by hypoxia-related genes, formed by HIF-1, which is related to several target genes that involve the energy metabolism, angiogenesis, and transmembrane carbonic anhydrases (CAs), mainly CA-IX that is one of the tumor-related carbonic anhydrases. The goal of this paper is to establish the role of CA-IX as a hypoxia marker in OSCC, while analyzing its expression in this type of tumors and its relationship with several clinical and pathological parameters and prognosis, evaluating its relationship with angiogenesis, other hypoxia markers, and clarifying its role in chemotherapy and radiotherapy resistance. [ABSTRACT FROM AUTHOR]

Inhibition of the metalloenzyme carbonic anhydrase (CA; EC 4.2.1.1) has pharmacologic applications in the field of anti-glaucoma, anti-convulsant and anti-cancer agents. But recently, it has also emerged that these enzymes have the potential for designing anti-infective drugs (anti-fungal and anti-bacterial agents) with a novel mechanism of action. Sulphonamides and their isosteres (sulphamates/sulphamides) constitute the main class of CA inhibitors (CAIs), which bind to the metal ion from the enzyme active site. Recently, the dithiocarbamates (DTCs), possessing a similar mechanism of action, were reported as a new class of inhibitors. These types of CAIs will be discussed in detail in this review. Novel drug design strategies have been reported ultimately based on the tail approach for obtaining sulphonamides/DTCs, which exploit more external binding regions within the enzyme active site (in addition to coordination to the metal ion), leading thus to isoform-selective compounds. Most of the promising data have been obtained by combining x-ray crystallography of enzyme-inhibitor adducts with novel synthetic approaches for generating chemical diversity. Whereas sulphonamide - NO donating hybrid drugs were reported as effective anti-glaucoma agents, most of the interesting new inhibitors were designed for inhibiting specifically the tumour-associated isoforms CA IX and XII, validated targets for imaging and treatment of hypoxic tumours. Promising compounds that inhibit CAs from bacterial and fungal pathogens, of the DTC and carboxylate types, will be also reviewed. [ABSTRACT FROM AUTHOR]

This paper presents result of quantitative structure-activity relationships (QSAR) study realized with the PRECLAV, omega, brood and MOPAC software. The dependent property is the inhibitory activity against human carbonic anhydrase mitochondrial isoforms VA and VB. The calibration set includes 17 aromatic/heterocyclic sulphonamides incorporating phenacetyl, pyridylacetyl and thienylacetyl tails with three clinically used CA inhibitors namely AZA, TPM and ZNS molecules. The prediction set contains 24 others not yet synthesized substituted aromatic/heterocyclic sulphonamides having unknown observed values of activity. In the presence of prediction set, the predictive quality of QSAR of hCA VA ( r2 = 0.9789, F = 418.115, r2CV = 0.9689) and hCA VB ( r2 = 0.9768; F = 379.717; r2CV = 0.9637) is large. The obtained models suggest a slightly different inhibition mechanism for the two isoforms. Large percentage, in weight, of CONH molecular fragments seems to be favourable to inhibitory activity of both VA and VB. [ABSTRACT FROM AUTHOR]

Carbonic anhydrases, catalysing the reversible CO2 hydration reaction, contribute in all living organisms to the maintenance of stable metabolic functions depending on intracellular concentrations of carbon dioxide, bicarbonate, and protons. Recent studies have examined how CAs affect bacterial lifecycle, considering these enzymes druggable targets due to interference with their activities by using inhibitors or activators. Here, we propose Escherichia coli cells as a model for testing the effect of acetazolamide (AZA), a potent CA inhibitor, on bacterial survival by evaluating E. coli growth through its glucose consumption. AZA, at concentrations higher than 31.2 µg/mL, was able to impair E. coli growth and glucose uptake. AZA is a good inhibitor of the two recombinant E. coli CAs, the β-CA CynT2, and the γ-CA EcoCAγ, with KIs of 227 and 248 nM, respectively. This study provides a proof-of-concept, low-cost method for identifying effective CA inhibitors capable of impairing bacterial metabolism. [ABSTRACT FROM AUTHOR]