(Hetero)aryl substituted thiazol-2,4-yl scaffold as human carbonic anhydrase I, II, VII and XIV activators.

Using histamine as lead molecule, a library of (hetero)aryl substituted thiazol-2,4-yl derivatives incorporating pyridine as proton shuttling moiety were obtained and investigated as activators of human carbonic anhydrase (CA, EC 4.2.1.1) isoforms I, II, VII and XIV. Some derivatives displayed good activating and selectivity profiles. This study provides an interesting opportunity to study the thiazole scaffold for the design of CA activators (CAAs), possibly acting on the central nervous system and targeting pathologies involving memory and learning impairments.

Synthesis and biological evaluation of new naphtho- and quinolinocyclopentane derivatives as potent melatoninergic (MT1/MT2) and serotoninergic (5-HT2C) dual ligands.

We recently reported a series of naphthofuranic compounds as constrained agomelatine analogues. Herein, in order to explore alternative ethyl amide side chain rigidification, naphthocyclopentane and quinolinocyclopentane derivatives with various acetamide modulations were synthesized and evaluated at both melatonin (MT1, MT2) and serotonin (5-HT2C) receptors. These modifications has led to compounds with promising dual affinity and high MTs receptors agonist activity. Enantiomeric separation was then performed on selected compounds allowing us to identify levogyre enantiomers (-)-17g and (-)-17k as the highest (MT1, MT2)/5-HT2C dual ligands described nowadays.

New quinolinic derivatives as melatonergic ligands: Synthesis and pharmacological evaluation.

New series of melatonergic ligands issued from two methoxy-quinolinic scaffolds (2-MQ and 3-MQ), were designed and synthesized. Herein we report the synthetic scheme and pharmacological results of the new prepared compounds. Investigation of compound 11a, the strict 2-MQ analogue, revealed the promising potential of this series. Therefore, pharmacomodulation of the acetamide function of 11a has led to compounds with different pharmacological profiles and the emergence of an MT2 selectivity. Besides, sulphonamide 11b showed the most important MT2 selectivity of this series (167 folds) while methyl and ethyl-ureas 11f and 11g represented the most potent melatonergic ligands of this study.

Hypoxia-targeting carbonic anhydrase IX inhibitors by a new series of nitroimidazole-sulfonamides/sulfamides/sulfamates.

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.

Targeting carbonic anhydrase IX by nitroimidazole based sulfamides enhances the therapeutic effect of tumor irradiation: a new concept of dual targeting drugs.

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.

Novel conformationally constrained analogues of agomelatine as new melatoninergic ligands.

Novel conformationally restricted analogues of agomelatine were synthesized and pharmacologically evaluated at MT1 and MT2 melatoninergic receptors. Replacement of the N-acetyl side chain of agomelatine by oxathiadiazole-2-oxide (compound 3), oxadiazole-5(4H)-one (compound 4), tetrazole (compound 5), oxazolidinone (compound 7a), pyrrolidinone (compound 7b), imidazolidinedione (compound 12), thiazole (compounds 13 and 14) and isoxazole moieties (compound 15) led to a decrease of the melatoninergic binding affinities, particularly at MT1. Compounds 7a and 7b exhibiting nanomolar affinity towards the MT2 receptors subtypes have shown the most interesting pharmacological results of this series with the appearance of a weak MT2-selectivity.

Design, synthesis and pharmacological evaluation of new series of naphthalenic analogues as melatoninergic (MT1/MT2) and serotoninergic 5-HT2C dual ligands (I).

As part of our ongoing interest in developing new melatoninergic ligands bearing the same pharmacological profile as agomelatine, we focused our attention on this compound as a lead. Several chemical modifications have been performed on positions C-3 and 8 of the naphthalene ring determined as primary targets for the agomelatine metabolism. Herein we report the modulation of the positions C-3 and 7 in addition of the amide side chain because of this later prominent role in the affinity profile of such ligands. Synthesized compounds were then biologically evaluated at human cloned melatoninergic and serotoninergic receptors and showed different binding affinity and intrinsic activity profiles. Compounds bearing fluoroacetamide group (compounds 4 and 5) showed a high melatoninergic binding affinity particularly towards MT(1) receptor subtype. Thus, the fluoroacetamide 4 exhibited a good melatoninergic (MT(1)/MT(2)) binding affinity (70 pM) higher than the lead. Moreover, other compounds (10a, 10e, 16, 17 and 18) issued from these modulations behaved as MT(1) and MT(2) agonists and exhibited a sub-nanomolar binding affinity towards these receptors. However, only compounds 10e, 17 and 18 showed a sub-nanomolar binding affinity at 5-HT(2C) higher than the agomelatine.

Synthesis of rhodamine B-benzenesulfonamide conjugates and their inhibitory activity against human α- and bacterial/fungal ß-carbonic anhydrases.

A series of fluorescent sulfonamide carbonic anhydrase (CA, EC 4.2.1.1) inhibitors were obtained by attaching rhodamine B moieties to the scaffold of benzenesulfonamides. The new compounds have been investigated for the inhibition of 12 human α-CA isoforms (hCA I-hCA XIV), three bacterial and one fungal ß-class enzymes from the pathogens Mycobacterium tuberculosis and Candida albicans. All types of inhibitory activities have been detected, with several compounds showing low nanomolar inhibition against the transmembrane isoforms hCA IX, XII (cancer-associated) and XIV. The ß-CAs were inhibited in the micromolar range by these compounds which may have applications for the imaging of hypoxic tumors or bacteria due to their fluorescent moieties.

Sulfonamides incorporating boroxazolidone moieties are potent inhibitors of the transmembrane, tumor-associated carbonic anhydrase isoforms IX and XII.

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.

Design and synthesis of naphthalenic derivatives as new ligands at the melatonin binding site MT3.

Naphthalenic analogs of MCA-NAT (5-methoxycarbonylamino-N-acetyltryptamine) have been synthesized and evaluated as melatonin receptor ligands. Introduction of a methoxycarbonylamino substituent at the C-7 position of the naphthalenic nucleus yields MT3 selective ligands. This selectivity can be modulated with suitable variations of the C-7 position and the acyl group on the C-1 side chain. We identified new series of compounds with affinity for the MT3 binding site in the nanomolar range, and singled out a selective ligand, (N-[2-(7-methylsulfamoyl-naphth-1-yl)ethyl]acetamide (17), with a Ki of 4.9 nM and selectivity of 1024 and 2040 versus MT1 and MT2 receptors respectively.

Carbonic anhydrase inhibitor coated gold nanoparticles selectively inhibit the tumor-associated isoform IX over the cytosolic isozymes I and II.

An approach for the synthesis of carbonic anhydrase (CA, EC 4.2.1.1) inhibitor coated gold nanoparticles is reported. This nanomaterial selectively inhibited the tumor-associated isoform CA IX overexpressed in hypoxic cancers over the ubiquitous, cytosolic housekeeping isozymes CA I and II and was membrane impermeant. As CA IX has an extracellular active site, the new nanomaterial which is confined to the extracellular space may be useful for imaging and treatment of hypoxic tumors.

Carbonic anhydrase inhibitors: 2-substituted-1,3,4-thiadiazole-5-sulfamides act as powerful and selective inhibitors of the mitochondrial isozymes VA and VB over the cytosolic and membrane-associated carbonic anhydrases I, II and IV.

A series of 2-substituted-1,3,4-thiadiazole-5-sulfamides was prepared and assayed as inhibitors of several carbonic anhydrase (CA, EC 4.2.1.1) isoforms, the cytosolic CA I and II, the membrane-associated CA IV and the mitochondrial CA VA and VB. The new compounds showed weak inhibitory activity against hCA I (K(I)s of 102 nM-7.42 microM), hCA II (K(I)s of 0.54-7.42 microM) and hCA IV (K(I)s of 4.32-10.05 microM) but were low nanomolar inhibitors of hCA VA and hCA VB, with inhibition constants in the range of 4.2-32 nM and 1.3-74 nM, respectively. Furthermore, the selectivity ratios for inhibiting the mitochondrial enzymes over CA II were in the range of 67.5-415, making these sulfamides the first selective CA VA/VB inhibitors.

Carbonic anhydrase inhibitors: design of membrane-impermeant copper(II) complexes of DTPA-, DOTA-, and TETA-tailed sulfonamides targeting the tumor-associated transmembrane isoform IX.

The synthesis and carbonic anhydrase (CA, EC 4.2.1.1) inhibitory activity of two series of aromatic sulfonamides and their Cu(II) derivatives, incorporating metal-complexing moieties of the DTPA, DOTA, and TETA type are reported. The new compounds were designed in such a way as to possess high affinity for Cu(II) ions, exploiting four pendant carboxylate moieties in the DTPA derivatives, as well as the cyclen/cyclam macrocyles, and three pendant acetate moieties in the DOTA and TETA derivatives. The new derivatives showed modest inhibition of the cytosolic isoform CA I (K(I) values in the range of 66-2130 nM), were better CA II inhibitors (K(I) values in the range of 21-360 nM), and excellent inhibitors of the tumor-associated isoform CA IX (K(I) values in the range of 4.1-110 nM), with selectivity ratios for the inhibition of the tumor (CA IX) over the cytosolic (CA II) isozyme in the range of 10.74-20.88 for the best derivatives. Copper complexes were more inhibitory than the corresponding ligand sulfonamides, and showed membrane impermeability, thus, having the possibility to specifically target the transmembrane CA IX that has an extracellular active site. Incorporation of radioactive copper isotopes in this type of CA inhibitor may lead to interesting diagnostic/therapeutic applications for such compounds.

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 anhydrase inhibitors: copper(II) complexes of polyamino-polycarboxylamido aromatic/heterocyclic sulfonamides are very potent inhibitors of the tumor-associated isoforms IX and XII.

Reaction of EDTA/DTPA dianhydride with aromatic/heterocyclic sulfonamides afforded a series of derivatives incorporating polyaminopolycarboxylate tails and benzenesulfonamide or 1,3,4-thiadiazole-2-sulfonamide heads. These compounds have been used as ligands to prepare Cu(II) complexes. Both parent sulfonamides as well as their copper complexes behaved as potent inhibitors of four carbonic anhydrase (CA, EC 4.2.1.1) isoforms, the cytosolic CA I and II, and transmembrane CA IX and XII. Some Cu(II) complexes showed subnanomolar affinities and some selectivity for the inhibition of the tumor-associated isoforms IX and XII and might be used as PET hypoxia markers of tumors.