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

Toward the Discovery of a Novel Class of Leads for High Altitude Disorders by Virtual Screening and Molecular Dynamics Approaches Targeting Carbonic Anhydrase

For decades, carbonic anhydrase (CA) inhibitors, most notably the acetazolamide-bearing 1,3,4-thiadiazole moiety, have been exploited at high altitudes to alleviate acute mountain sickness, a syndrome of symptomatic sensitivity to the altitude characterized by nausea, lethargy, headache, anorexia, and inadequate sleep. Therefore, inhibition of CA may be a promising therapeutic strategy for high-altitude disorders. In this study, co-crystallized inhibitors with 1,3,4-thiadiazole, 1,3-benzothiazole, and 1,2,5-oxadiazole scaffolds were employed for pharmacophore-based virtual screening of the ZINC database, followed by molecular docking and molecular dynamics simulation studies against CA to find possible ligands that may emerge as promising inhibitors. Compared to the co-crystal ligands of PDB-1YDB, 6BCC, and 6IC2, ZINC12336992, ZINC24751284, and ZINC58324738 had the highest docking scores of -9.0, -9.0, and -8.9 kcal/mol, respectively. A molecular dynamics (MD) simulation analysis of 100 ns was conducted to verify the interactions of the top-scoring molecules with CA. The system's backbone revealed minor fluctuations, indicating that the CA-ligand complex was stable during the simulation period. Simulated trajectories were used for the MM-GBSA analysis, showing free binding energies of -16.00 ± 0.19, -21.04 ± 0.17, and -19.70 ± 0.18 kcal/mol, respectively. In addition, study of the frontier molecular orbitals of these compounds by DFT-based optimization at the level of B3LYP and the 6-311G(d,p) basis set showed negative values of the HOMO and LUMO, indicating that the ligands are energetically stable, which is essential for forming a stable ligand-protein complex. These molecules may prove to be a promising therapy for high-altitude disorders, necessitating further investigations.

Tetrahydroquinazole-based secondary sulphonamides as carbonic anhydrase inhibitors: synthesis, biological evaluation against isoforms I, II, IV, and IX, and computational studies

A library of variously decorated N-phenyl secondary sulphonamides featuring the bicyclic tetrahydroquinazole scaffold was synthesised and biologically evaluated for their inhibitory activity against human carbonic anhydrase (hCA) I, II, IV, and IX. Of note, several compounds were identified showing submicromolar potency and excellent selectivity for the tumour-related hCA IX isoform. Structure-activity relationship data attained for various substitutions were rationalised by molecular modelling studies in terms of both inhibitory activity and selectivity.

Synthesis and carbonic anhydrase inhibitory properties of novel 4-(2-aminoethyl)benzenesulfonamide-dipeptide conjugates

Thirty novel sulfonamide derivatives incorporating dipeptide were synthesized by facile acylation through benzotriazole mediated reactions and their structures were identified by ¹H NMR, ¹³C NMR, MS and FT-IR spectroscopic techniques and elemental analysis. The carbonic anhydrase (CA, EC 4.2.1.1) inhibitory activity of the new compounds was assessed against four human (h) isoforms, hCA I, hCA II, hCA IV and hCA XII. Most of the synthesized compounds showed excellent in vitro carbonic anhydrase inhibitory properties comparable to those of the clinically used drug acetazolamide (AAZ). The new unprotected dipeptide-sulfonamide conjugates showed very effective inhibitory activity, in the low nanomolar range against II and XII, being less effective as hCA I and IV inhibitors. Four of the thirty compounds also showed strong inhibitory activity against hCA XII compared to AAZ.

Inhibition of carbonic anhydrase IX targets primary tumors, metastases, and cancer stem cells: Three for the price of one

Human carbonic anhydrase (CA) IX is a tumor-associated protein, since it is scarcely present in normal tissues, but highly overexpressed in a large number of solid tumors, where it actively contributes to survival and metastatic spread of tumor cells. Due to these features, the characterization of its biochemical, structural, and functional features for drug design purposes has been extensively carried out, with consequent development of several highly selective small molecule inhibitors and monoclonal antibodies to be used for different purposes. Aim of this review is to provide a comprehensive state-of-the-art of studies performed on this enzyme, regarding structural, functional, and biomedical aspects, as well as the development of molecules with diagnostic and therapeutic applications for cancer treatment. A brief description of additional pharmacologic applications for CA IX inhibition in other diseases, such as arthritis and ischemia, is also provided.

Novel eugenol derivatives: Potent acetylcholinesterase and carbonic anhydrase inhibitors

Eugenol was used as starting material to obtain some phenolic compounds. The synthesis of these phenolic compounds was performed in a two-step procedure. The structures of the formed products (novel eugenol derivatives 1-6) have been determined on the basis of NMR spectroscopy and other spectroscopic methods. The compounds were tested in terms of carbonic anhydrase (CA) inhibition potency. Carbonic anhydrases (CAs, EC 4.2.1.1) are metalloenzymes, which catalyse the reaction between carbon dioxide (CO₂) and water (H₂O), to generate bicarbonate (HCO₃^-) and protons (H⁺). CO₂, HCO₃^- and H⁺ are essential molecules and ions for many important physiologic processes occurring in all living organisms. Acetylcholinesterase (AChE, E.C.3.1.1.7) is found in high concentrations in the red blood cells and brain. Novel eugenol derivatives (1-6) were tested for the inhibition of two cytosolic CA isoforms I, and II (hCA I, and II) and AChE. These compounds demonstrated effective inhibitory profiles with Ki values in ranging of 113.48-738.69nM against hCA I, 92.35-530.81nM against hCA II, and 90.10-379.57nM against AChE, respectively. On the other hand, acetazolamide clinically used as CA inhibitor, shoed Ki value of 594.11nM against hCA I, and 120.68nM against hCA II, respectively. Also, AChE was inhibited by tacrine as an AChE inhibitor at the 71.18nM level.

Open saccharin-based secondary sulfonamides as potent and selective inhibitors of cancer-related carbonic anhydrase IX and XII isoforms

A large number of novel secondary sulfonamides based on the open saccharin scaffold were synthesized and evaluated as selective inhibitors of four different isoforms of human carbonic anhydrase (hCA I, II, IX and XII, EC 4.2.1.1). They were obtained by reductive ring opening of the newly synthesized N-alkylated saccharin derivatives and were shown to be inactive against the two cytosolic off-target hCA I and II (K_is > 10 µM). Interestingly, these compounds inhibited hCA IX in the low nanomolar range with K_is ranging between 20 and 298 nM and were extremely potent inhibitors of hCA XII isoenzyme (K_is ranging between 4.3 and 432 nM). Since hCA IX and XII are the cancer-related isoforms recently validated as drug targets, these results represent an important goal in the development of new anticancer candidates. Finally, a computational approach has been performed to better correlate the biological data to the binding mode of these inhibitors.

Carbonic anhydrase XII is a new therapeutic target to overcome chemoresistance in cancer cells

Multidrug resistance (MDR) in cancer cells is a challenging phenomenon often associated with P-glycoprotein (Pgp) surface expression. Finding new ways to bypass Pgp-mediated MDR still remains a daunting challenge towards the successful treatment of malignant neoplasms such as colorectal cancer.

We applied the Cell Surface Capture technology to chemosensitive and chemoresistant human colon cancer to explore the cell surface proteome of Pgp-expressing cells in a discovery-driven fashion. Comparative quantitative analysis of identified cell surface glycoproteins revealed carbonic anhydrase type XII (CAXII) to be up-regulated on the surface of chemoresistant cells, similarly to Pgp. In cellular models showing an acquired MDR phenotype due to the selective pressure of chemotherapy, the progressive increase of the transcription factor hypoxia-inducible factor-1 alpha was paralleled by the simultaneous up-regulation of Pgp and CAXII. CAXII and Pgp physically interacted at the cell surface. CAXII silencing or pharmacological inhibition with acetazolamide decreased the ATPase activity of Pgp by altering the optimal pH at which Pgp operated and promoted chemosensitization to Pgp substrates in MDR cells.

We propose CAXII as a new secondary marker of the MDR phenotype that influences Pgp activity directly and can be used as a pharmacological target for MDR research and potential treatment.

Synthesis of N-alkyl (aril)-tetra pyrimidine thiones and investigation of their human carbonic anhydrase I and II inhibitory effects

Tetrahydropyrimidine thiones, which are cyclic thiocarbamides derivatives, were synthesised from thiourea, β-diketones and substituted benzaldehydes. A tautomeric form of these derivatives incorporates the thiol functionality, which is known to interact with metal ions from metalloenzymes active sites, such as the carbonic anhydrases (CAs, EC 4.2.1.1) among others. This is a superfamily of widespread enzymes, which catalyses a crucial biochemical reaction, the reversible hydration of carbon dioxide to bicarbonate and protons (H(+)). The newly synthesised N-alkyl (aril)-tetrahydropyrimidine thiones were tested for inhibition of the cytosolic human isoforms I and II (hCA I and II). Both isoforms were effectively inhibited by the newly synthesised thiones. Ki values were in the range of 218.5 ± 23.9-261.0 ± 41.5 pM for hCA I, and of 181.8 ± 41.9-273.6 ± 41.4 pM for hCA II, respectively. This under-investigated class of derivatives may bring interesting insights in the field of non-sulphonamide CA inhibitors.

Benzenesulfonamide bearing 1,2,4-triazole scaffolds as potent inhibitors of tumor associated carbonic anhydrase isoforms hCA IX and hCA XII

Three series of novel heterocyclic compounds (3a-3g, 4a-4g and 5a-5g) containing benzenesulfonamide moiety and incorporating a 1,2,4-triazole ring, have been synthesized and investigated as inhibitors against four isomers of the α-class carbonic anhydrases (CAs, EC 4.2.1.1), comprising hCAs I and II (cytosolic, ubiquitous isozymes) and hCAs IX and XII (transmembrane, tumor associated isozymes). Against the human isozymes hCA I and II, compounds of two series (3a-3g and 4a-4g) showed Ki values in the range of 84-868 nM and 5.6-390 nM, respectively whereas compounds of series 5a-5g were found to be poor inhibitors (Ki values exceeding 10,000 nM in some cases). Against hCA IX and XII, all the tested compounds exhibited excellent to moderate inhibitory potential with Ki values in the range of 2.8-431 nM and 1.3-63 nM, respectively. Compounds 3d, 3f and 4f exhibited excellent inhibitory potential against all of the four isozymes hCA I, II, IX and XII, even better than the standard drug acetazolamide (AZA) whereas compound of the series 5a-5g were comparatively less potent but more selective towards hCA IX and XII.