Human Carbonic Anhydrase Inhibitors Research Articles

Synthesis of Chromene-linked Bis-indole Derivatives as Selective Tumor-associated Carbonic Anhydrase IX Inhibitors.

Sulfonamide derivatives are well-reported hCA IX inhibitors; however, they inhibit all types of hCA without any selectivity, leading to severe adverse effects. Hence, developing a novel nonsulfonamide class of tumor-associated hCA IX inhibitors through non-classical inhibition may provide greater selectivity and better pharmacokinetics. The objective of this study was to develop non-sulfonamide derivatives as potential human carbonic anhydrase (hCA) inhibitors and develop a new series of chromene-linked bis-indole derivatives. We synthesized and characterized the chromene-linked bis-indole derivatives and further evaluated them against four hCA isoforms, i.e., hCA I, hCA II, hCA IX, and hCA XII, and determined the ADMET parameters by the In-silico method. Most of the compounds showed significantly greater affinity and selectivity towards the tumorassociated hCA IX over other hCA isoforms within the lower micromolar to submicromolar range. In particular, the bromo-substituted bis-indole derivative 6t showed an excellent inhibition of hCA IX isoform with an affinity (Ki) of 2.61 μM. In contrast, the cyano group substituted bis-indole derivative 6s and also displayed a strong inhibition of hCA IX isoform with an affinity (Ki) of 2.73 μM. Many other potential candidates, including 6g, 6i, 6k, 6m, 6o, 6p, and 6r, showed higher affinity at tumor-associated hCA IX with lower than 10 μM compared to other hCA isoforms. Therefore, the chromene-linked bis-indole derivatives can serve as a novel non-sulfonamide class of tumor-associated hCA IX inhibitors.

Exploration of 1,3,5-trisubstituted pyrazoline derivatives as human carbonic anhydrase inhibitors: Synthesis, biological evaluation and in silico studies

The human carbonic anhydrase (hCA) IX and XII isoforms are overexpressed in hypoxic conditions, contributing to cancer. Lack of isoform selectivity has been one of the main challenges associated with the existing drugs targeting hCAs. Hence, the development of alternative approaches, such as tail approach to develop more selective hCA IX and XII inhibitors is need of the hour. In the present work, we designed and synthesized 24 new 1,3.5-trisubstituted-pyrazoline derivatives with diverse substitutions. The synthesized analogs were evaluated for their hCA inhibitory activities against hCA I, II, IX, and XII isoforms. Among the tested compounds, derivative 8 displayed good inhibitory activity against hCA IX (Ki = 331 nM) and XII (Ki = 96.7 nM). In addition, 9a-g also exhibited some inhibitory activities against hCA IX and XII, with Kis ranging from 574 to 799 nM and 137–369 nM, respectively. Molecular modelling studies of compound 8 displayed metal coordination with zinc ion and hydrophobic, hydrophilic interactions with adjacent amino acid residues, and maintained stable interactions throughout 100 ns. In addition, ADMET studies demonstrated that compound 8 obeyed the Lipinski's rule of five and was found to be druggable and non-toxic. Hence, compound 8 was identified as potential lead for further development.

Design, synthesis of antipyrine-based Schiff bases and investigation of their cholinesterase and carbonic anhydrase activities by in vitro and in silico approaches

In this study, a series of antipyrine-based Schiff bases (1-10) was designed, synthesized, and evaluated as potential inhibitors of various metabolic enzymes, including acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and human erythrocyte carbonic anhydrase I and II (hCA I and hCA II). The target molecules were characterized by UV-Vis, FT-IR, 1H NMR, 13CNMR, LC-HRMS, and elemental analysis. All tested derivatives demonstrated low nanomolar inhibition with Ki values of in the range of 20.58 ± 0.35 to 53.11 ± 1.02 nM against AChE, 21.84 ± 0.40 to 54.41 ± 1.05 nM against BChE, 27.45 ± 0.41 to 48.22 ± 0.91 nM against cytosolic hCA I isoform associated with epilepsy, and 6.02 ± 0.11 to 29.32 ± 0.54 nM against cytosolic hCA II isoform associated with glaucoma. In general, most these molecules, except for a few, inhibited these enzymes more than acetazolamide (AZA) and neostigmine. Among them, compounds 5, 7, 8, and 9 showed the best inhibitory activities against AChE, BChE, hCA I, and hCA II, respectively. Docking results were calculated for the compounds that showed the best inhibitory activity against these enzymes and for reference compounds. Based on the molecular docking results, they were determined to have high binding energies, including hydrogen bonds, electrostatic interactions, and hydrophobic interactions. Absorption, distribution, metabolism, and excretion (ADME) parameters determined that all the synthesized pyrazolone ring-bearing Schif base derivatives (1-10) have the expected physicochemical properties in terms of drug-likeness and can be evaluated as orally active potential. Properties such as the electrophilicity index and chemical hardness were also investigated by density functional theory (DFT) at the B3LYP/6-311G** level of theory.

Preyssler heteropolyacid-mediated direct deprotection/N-benzoylation of N-Boc-protected sulfonamides: synthesis, molecular docking, DFT study and in-silico ADME evaluation of novel benzamides bearing the sulfonamide moiety as possible inhibitors of human carbonic anhydrase II

An adequate method is described for the synthesis of new substituted benzamides containing a sulfonamide moiety using Preyssler heteropolyacid H14[NaP5W30O110] as an efficient catalyst. This method proceeds in one-step, including deprotection and benzoylation of N-(tert-butoxycarbonyl) sulfonamides to give the target compounds good yields (up to 92%). A molecular docking was performed to study the interactions between the synthesized benzamides and human carbonic anhydrases II. It was concluded that all compounds demonstrated good binding score values (up to −9.4 kcal/mol) for the active site of all selected proteins when compared with the reference drug Acetazolamide (−6.3 kcal/mol). In addition, the ADME/T analyses show that all synthesized molecules exhibited good pharmacokinetics and bioavailability. The theoretical calculations for all compounds were performed using the DFT/B3LYP/6–31G (d,p) level of theory. The study yielded optimized structural parameters, global reactivity descriptors, and Frontier Molecular Orbitals (FMO’s).

Phosphorylation strongly affects the inhibition of human carbonic anhydrase I CO2 hydration activity

Human carbonic anhydrases (hCAs) have essential roles in respiration, acid-base balance, and fluid secretion, with implications in diseases such as glaucoma, epilepsy, obesity, and cancer. Of the fifteen known hCAs, human CA I (hCA I) is particularly abundant in erythrocytes, playing a critical role in CO2 transport. Despite extensive research on hCA I, the impact of post-translational modifications (PTMs), particularly phosphorylation, on its catalytic activity and inhibitor binding remains poorly understood. Although multiple phosphorylation sites have been identified in hCA I in vivo through high-throughput proteomics studies including at the highly conserved Ser51 residue, the functional consequences of these modifications are not well characterized. We investigated the effects of a phosphomimetic mutation at Ser51 on hCA I, examining its catalytic efficiency and susceptibility to inhibition by sulfonamides and anions. Using a recombinant expression system and a stopped-flow kinetic assay, we characterized the CO2 hydration activity and inhibition profiles of S51E hCA I compared to the wild type enzyme. Our results demonstrate that the S51E mutation increases the catalytic turnover rate (kcat) from 2.0 × 105 s−1 to 2.6 × 105 s−1 but significantly decreases substrate affinity, raising the Michaelis constant (KM) from 4.0 mM to 13.9 mM, reducing overall catalytic efficiency by over 50 %. Inhibition studies with a panel of 41 sulfonamides revealed that the S51E mutation dramatically alters inhibitor sensitivity, particularly for the most effective inhibitors. For example, 15 of the 16 most effective sulfonamide inhibitors for hCA I (with KIs <350 nM) were an average of over 35-fold less effective in inhibiting S51E hCA I than the wild type. The KI of the anticonvulsant zonisamide increased from 31 nM for the wild type hCA I to 4.0 μM. The inhibition profile with a panel of 37 small anions further indicated that the S51E mutant exhibited significantly reduced susceptibility to inhibition by 24 out of 37 tested anions, with some KI values increasing by up to 11,000-fold for inhibitors like hydrogen sulfide. This study underscores the significant impact that phosphorylation may have on hCA I function and inhibition. By characterizing the effects of phosphorylation on the CO2 hydration activity and inhibitor sensitivity of hCA I, these findings represent early steps in developing more selective proteoform-specific inhibitors, which could lead to more effective treatments for diseases involving carbonic anhydrases.

Lasamide, a Potent Human Carbonic Anhydrase Inhibitor from the Market: Inhibition Profiling and Crystallographic Studies.

Lasamide is a synthetic precursor and a contaminant of the diuretic Furosemide manufacturing process and represents a highly valuable building block for fragment-based drug discovery approaches. We assessed the ability of Lasamide to inhibit in vitro the human-expressed Carbonic Anhydrases by means of the stopped-flow technique, and we assessed its binding modes within hCAs II and XII-mimic catalytic clefts by X-ray crystallography. Interestingly, an unprecedented crystal form for the hCA IX mimic H-tag is reported and discussed herein.

Optimization of Ethoxzolamide Analogs with Improved Pharmacokinetic Properties for In Vivo Efficacy against Neisseria gonorrhoeae.

Drug-resistant gonorrhea is caused by the bacterial pathogen Neisseria gonorrhoeae, for which there is no recommended oral treatment. We have demonstrated that the FDA-approved human carbonic anhydrase inhibitor ethoxzolamide potently inhibits N. gonorrhoeae; however, is not effective at reducing N. gonorrhoeae bioburden in a mouse model. Thus, we sought to optimize the pharmacokinetic properties of the ethoxzolamide scaffold. These efforts resulted in analogs with improved activity against N. gonorrhoeae, increased metabolic stability in mouse liver microsomes, and improved Caco-2 permeability compared to ethoxzolamide. Improvement in these properties resulted in increased plasma exposure in vivo after oral dosing. Top compounds were investigated for in vivo efficacy in a vaginal mouse model of gonococcal genital tract infection, and they significantly decreased the gonococcal burden compared to vehicle and ethoxzolamide controls. Altogether, results from this study provide evidence that ethoxzolamide-based compounds have the potential to be effective oral therapeutics against gonococcal infection.

Development of novel organometallic sulfonamides with N-ethyl or N-methyl benzenesulfonamide units as potential human carbonic anhydrase I, II, IX and XII isoforms' inhibitors: Synthesis, biological evaluation and docking studies

In the search of new cymantrenyl- and ferrocenyl-sulfonamides as potencial inhibitors of human carbonic anhydrases (hCAs), four compounds based on N-ethyl or N-methyl benzenesulfonamide units have been obtained. These cymantrenyl (1a-b) and ferrocenyl (2a-b) derivatives were prepared by the reaction between aminobenzene sulfonamides ([NH2-(CH2)n-(C6H4)-SO2-NH2)], where n = 1, 2) with cymantrenyl sulfonyl chloride (P1) or ferrocenyl sulfonyl chloride (P2), respectively. All compounds were characterized by conventional spectroscopic techniques and cyclic voltammetry. In the solid state, the molecular structures of compounds 1a, 1b, and 2b were determined by single-crystal X–ray diffraction. Biological evaluation as carbonic anhydrases inhibitors were carried out and showed derivatives 1b y 2b present a higher inhibition than the drug control for the Human Carbonic Anhydrase (hCA) II and IX isoforms (KI = 7.3 nM and 5.8 nM, respectively) and behave as selective inhibition for hCA II isoform. Finally, the docking studies confirmed they share the same binding site and interactions as the known inhibitors acetazolamide (AAZ) and agree with biological studies.

Investigation on the Crystal Structures of Molecules Related to 2‐(Benzylsulfinyl)Benzoic Acid, As a Support to the Studies on the Inhibition of Human Carbonic Anhydrases

AbstractA recent interest attaches to the derivatives of the (2‐benzylsulfinyl)benzoic acid as inhibitors of human carbonic anhydrases (hCAs), an action that can be applied in innovative therapies. A set of crystal structures of six sulfides and six enantiopure sulfoxides related to this scaffold, taken from the literature, or derived from the work on the asymmetric synthesis of sulfinyl compounds, is investigated. The lattice energies of these structures are estimated by means of the Crystal Explorer 21 program. The weak interactions building up the crystal structures are identified, and their contributions are analyzed in comparison with the calculated lattice energies. The most stable conformations in the solid phase are identified. It is worth observing that the sulfides of the scaffold under investigation behave almost in the same manner; on the other hand, the presence of the sulfinyl group of the sulfoxides adds complexity, that shall be taken into account in future docking calculations of these molecules with the hCAs enzymes.

A new framework for novel analogues of pazopanib as potent and selective human carbonic anhydrase inhibitors: Design, repurposing rational, synthesis, crystallographic, in vivo and in vitro biological assessments

Herein, we describe the design and synthesis of novel aryl pyrimidine benzenesulfonamides APBSs 5a-n, 6a-c, 7a-b, and 8 as pazopanib analogues to explore new potent and selective inhibitors for the CA IX. All APBSs were examined in vitro for their promising inhibition activity against a small panel of hCAs (isoforms I, II, IX, and XII). The X-ray crystal structure of CA I in adduct with a representative APBS analogue was solved. APBS-5m, endowed with the best hCA IX inhibitory efficacy and selectivity, was evaluated for antiproliferative activity against a small panel of different cancer cell lines, SK-MEL-173, MDA-MB-231, A549, HCT-116, and HeLa, and it demonstrated one-digit IC50 values range from 2.93 μM (MDA-MB-231) to 5.86 μM (A549). Furthermore, compound APBS-5m was evaluated for its influence on hypoxia-inducible factor (HIF-1α) production, apoptosis induction, and colony formation in MDA-MB-231 cancer cells. The in vivo efficacy of APBS-5m as an antitumor agent was additionally investigated in an animal model of Solid Ehrlich Carcinoma (SEC). In order to offer perceptions into the conveyed hCA IX inhibitory efficacy and selectivity in silico, a molecular docking investigation was also carried out.

Novel 2,4-Dichloro-5-sulfamoylbenzoic Acid Oxime Esters: First Studies as Potential Human Carbonic Anhydrase Inhibitors.

In this study, a focused library of oxime ester derivatives of 2,4-dichloro-5-sulfamoylbenzoic acid (lasamide) containing Schiff bases was synthesized and tested in vitro for their ability to inhibit the cytosolic human carbonic anhydrases (hCAs) I and II, as well as the transmembrane and tumor-associated IX and XII isoforms. As a result, we obtained a first line of knowledge on lasamide derivatives potentially useful for development as CA inhibitors (CAIs). In particular, we focused our attention on the derivative 11, which was selective toward hCAs IX and XII over the cytosolic isoenzymes. An in silico study was conducted to assess the binding mode of 11 within hCAs IX and XII. Also, antiproliferative assays highlighted promising derivatives. The data obtained in this study are currently in use for the development of better-performing compounds on the tumor-associated isoforms.

Novel Anthraquinone-Based Benzenesulfonamide Derivatives and Their Analogues as Potent Human Carbonic Anhydrase Inhibitors with Antitumor Activity: Synthesis, Biological Evaluation, and In Silico Analysis.

In this study, we designed two series of novel anthraquinone-based benzenesulfonamide derivatives and their analogues as potential carbonic anhydrase inhibitors (CAIs) and evaluated their inhibitory activities against off-target human carbonic anhydrase II (hCA II) isoform and tumor-associated human carbonic anhydrase IX (hCA IX) isoform. Most of these compounds exhibited good inhibitory activities against hCA II and IX. The compounds that exhibited the best hCA inhibition were further studied against the MDA-MB-231, MCF-7, and HepG2 cell lines under hypoxic and normoxic conditions. Additionally, the compounds exhibiting the best antitumor activity were subjected to apoptosis and mitochondrial membrane potential assays, which revealed a significant increase in the percentage of apoptotic cells and a notable decrease in cell viability. Molecular docking studies were performed to demonstrate the presence of numerous hydrogen bonds and hydrophobic interactions between the compounds and the active site of hCA. Absorption, distribution, metabolism, excretion (ADME) predictions showed that all of the compounds had good pharmacokinetic and physicochemical properties.

Discovery of a New Class of 1-(4-Sulfamoylbenzoyl)piperidine-4-carboxamides as Human Carbonic Anhydrase Inhibitors.

A series of 1-(4-sulfamoylbenzoyl)piperidine-4-carboxamides deriving from substituted piperazines/benzylamines was designed, synthesized, and tested on human carbonic anhydrase (hCA). The inhibitory activity of the new sulfonamides was analyzed using acetazolamide (AAZ) as a standard inhibitor against hCA I, II, IX, and XII. Several sulfonamides showed both inhibitory activity at low nanomolar concentrations and selectivity against the cytosolic hCA II isoform, and the same trend was observed on the tumor-associated hCA IX and XII. The benzenesulfonamido carboxamides 11 and 15 were the most potent of the piperazino- and benzylamino-based series, respectively. Docking and molecular dynamics studies related the high selectivity of compound 11 toward the tumor-associated hCA isoforms to its capability to participate in favorable interactions within hCA IX and hCA XII active sites, whereas no such interactions were detected within both hCA I and hCA II isoforms.

Synthesis of 4-sulfamoyl phenyl diazocarboxylic acid derivatives as novel non-classical inhibitors of human carbonic anhydrase II activity: an in vitro study

The first class of carbonic anhydrase inhibitors (CAIs) discovered was sulfonamides, but their clinical use is limited due to side effects caused by their inhibition of multiple CA isoforms. To overcome this, researchers have focused on developing isoform-selective CAIs. This study involved the synthesis and characterization of novel carboxylic acid/sulfonamide derivatives. We investigated the interaction between these compounds and the human carbonic anhydrase II (hCA II) isoform using spectroscopic and computational methods. The synthesized compounds were evaluated based on their IC50, K d and K i values, and it was found that the inhibitory potency and binding affinity of the compounds increased with the number of carboxylic acids zinc binding groups. Specifically, the compound C4, with three carboxylic acid groups, showed the strongest inhibitory potency. Fluorescence measurements revealed that all compounds quenched the intrinsic fluorescence of hCA II through a dynamic quenching process, and each compound had one binding site in the hCA II structure. Thermodynamic analysis indicated hydrogen bonds and van der Waals interactions played key roles in the binding of these compounds to hCA II. Docking studies showed that the carboxylic acid groups directly attached to the zinc ion in the active site, displacing water/hydroxide ions and causing steric hindrance. Overall, the strengthening of inhibitory activity and the binding power of these carboxylic acid derivatives for the hCA II makes these compounds interesting for designing novel hCA II inhibitors. Communicated by Ramaswamy H. Sarma

Novel 2-(hydrazinocarbonyl)-3-phenyl-1H-indole-5-sulfonamide based thiosemicarbazides as potent and selective inhibitors of tumor-associated human carbonic anhydrase IX and XII: Synthesis, cytotoxicity, and molecular modelling studies

In the pursuit of discovering new selective carbonic anhydrase (CA, EC 4.2.1.1) inhibitors, a small collection of novel thiosemicarbazides (5a-5t) were designed and synthesized starting from 2-(hydrazinocarbonyl)-3-phenyl-1H-indole-5-sulfonamide which was evaluated as a potent inhibitor of different CA isoforms in a previous study. The newly synthesized compounds were examined against four human carbonic anhydrases (hCA), namely transmembrane tumor-related hCA IX/XII and cytosolic widespread off-targets hCA I/II. In enzyme inhibition assays, all nineteen compounds display up to ∼340-fold selectivity for hCA IX/XII over off-target isoforms hCA I/II. Four compounds have enzyme inhibition values (Ki) lower than 10 nM against tumor-associated isoforms hCA IX/XII including two compounds in the subnanomolar range (5r and 5s; hCA XII; Ki: 0.69 and 0.87 nM). The potential binding interactions of the most potent compounds against hCA IX and XII, compounds 5s and 5r, respectively, were investigated using ensemble docking and molecular dynamics studies. Cell viability assays using human colorectal adenocarcinoma cell line HT-29 and healthy skin fibroblasts CCD-86Sk show that compound 5e selectively inhibits HT-29 cancer cell proliferation (IC50: 53.32 ± 7.74 µM for HT-29; IC50: 74.64 ± 14.15 µM for CCD-986Sk). Finally, Western blot assays show that compounds 5e and 5r significantly reduce the expression of hCA XII in HT-29 cells. Moreover, 5e shows better cytotoxic activity in hypoxia compared to normoxic conditions. Altogether, the newly designed compounds show stronger inhibition of the tumor-associated hCA IX and XII isoforms and several tested compounds show selective cytotoxicity as well as downregulation of hCA XII expression.

Synthesis, biological evaluation and molecular docking studies of novel 1,3,4-thiadiazoles as potential anticancer agents and human carbonic anhydrase inhibitors.

Thiosemicarbazide and also 1,3,4-thiadiazole derivatives have been garnering substantial attention from researchers worldwide due to their expansive range of biological activities, encompassing antimicrobial, anti-inflammatory, and anticancer properties. Herein, we embarked on a comprehensive investigation in this study, introducing a novel series of thiosemicarbazides (3a-3i) and their corresponding 1,3,4-thiadiazole (4a-4i) derivatives. The compounds were meticulously designed, synthesized, and subjected to meticulous characterization using various spectroscopic methods such as FT-IR, 1H-NMR, 13C-NMR, and elemental analysis. Afterward, their potential anti-proliferative effectiveness was assessed using MTT assay against two cancer cell lines (U87 and HeLa) and normal fibroblast cells (L929). Among the compounds, 4d showed the highest cytotoxic activity against U87 and 4i against HeLa. Compound 3b exhibited selective cytotoxic activity against both cancer cells. Among the molecules with selective activity against the U87 cell line; 3a, 3b, 4d and 4e were further evaluated by caspase-3 activity levels, Bax and Bcl-2 protein expression, and total oxidant status assay. Besides, carbonic anhydrase IX activity studies were also performed in order to understand the underlying mechanism of action. The results indicated that compound 4e showed higher efficacy than standard acetazolamide (IC50 = 0.58 ± 0.02 µM) with an IC50 value of 0.03 ± 0.01 µM. Furthermore, molecular docking studies were carried out using carbonic anhydrase IX crystals to determine the compound's interactions with the enzyme's active sites. This comprehensive investigation sheds light on the intricate interplay between molecular structure and biological activity, providing valuable insights into the therapeutic potential of these compounds.

4-(3-Phenyl-4-(3,4,5-trimethoxybenzoyl)-1H-pyrrol-1-yl)benzenesulfonamide, a Novel Carbonic Anhydrase and Wnt/β-Catenin Signaling Pathway Dual-Targeting Inhibitor with Potent Activity against Multidrug Resistant Cancer Cells.

We synthesized new pyrrole and indole derivatives as human carbonic anhydrase (hCA) inhibitors with the potential to inhibit the Wnt/β-catenin signaling pathway. The presence of both N1-(4-sulfonamidophenyl) and 3-(3,4,5-trimethoxyphenyl) substituents was essential for strong hCA inhibitors. The most potent hCA XII inhibitor 15 (Ki = 6.8 nM) suppressed the Wnt/β-catenin signaling pathway and its target genes MYC, Fgf20, and Sall4 and exhibited the typical markers of apoptosis, cleaved poly(ADP-ribose)polymerase, and cleaved caspase-3. Compound 15 showed strong inhibition of viability in a panel of cancer cells, including colorectal cancer and triple-negative breast cancer cells, was effective against the NCI/ADR-RES DOX-resistant cell line, and restored the sensitivity to doxorubicin (DOX) in HT29/DX and MDCK/P-gp cells. Compound 15 is a novel dual-targeting compound with activity against hCA and Wnt/β-catenin. It thus has a broad targeting spectrum and is an anticancer agent with specific potential in P-glycoprotein overexpressing cell lines.

Molecular docking and inhibition profiles of some antidepressants on human carbonic anhydrase enzymes

Inhibition of human carbonic anhydrase (hCA) enzymes is a bright target since these isoenzymes take part in various physiological events and inhibitors of these enzymes are potent drug candidates for several diseases. In this study, we investigated the influences of commonly used antidepressants, risperidone, mirtazapine and sodium valproate on hCA I and II and deter-mined their kinetics. Antidepressant compounds showed Ki values ranging from 0.0054 to 222.5 µM against hCA I, 0.0004 to 392.9 µM against hCA II. According to the molecular docking study, risperidone and mirtazapine which are the most active inhibitors have the glide scores with 6.568 kcal/mol and −7.385 kcal/mol against hCA I and hCA II enzymes, respectively. The binding analysis of the inhibitor-enzyme complexes has revealed that their inhibition mechanisms result from interactions with the critical residue of the catalytic active site or Zn atom. Our finding shows that antidepressants have crucial inhibition effects on CA enzymes and that risperidone was found to be much more effective than acetazolamide, a standard clinically used inhibitor of carbonic anhydrase. As inhibitors of CA enzymes are important drug candidates for various diseases, risperidone is a promising compound which needs to be further investigated to produce novel derivatives.

Design, synthesis, and biological investigation of selective human carbonic anhydrase II, IX, and XII inhibitors using 7-aryl/heteroaryl triazolopyrimidines bearing a sulfanilamide scaffold

A novel library of human carbonic anhydrase (hCA) inhibitors based on the 2-sulfanilamido[1,2,4]triazolo[1,5-a]pyrimidine skeleton modified at its 7-position was prepared by an efficient convergent procedure. These derivatives were evaluated in vitro for their inhibition properties against a representative panel of hCA isoforms (hCA I, II, IV, IX, and XII). The target tumour-associated isoforms hCA IX and XII were potently inhibited with K Is in the low nanomolar range of 5–96 nM and 4–72 nM, respectively. Compounds 1d, 1j, 1v, and 1x were the most potent hCA IX inhibitors with K Is of 5.1, 8.6, 4.7, and 5.1 nM, respectively. Along with derivatives 1d and 1j, compounds 1r and 1ab potently inhibited hCA XII isoform with K Is in a single-digit nanomolar range of 8.8, 5.4, 4.3, and 9.0 nM, respectively. Compounds 1e, 1m, and 1p exhibited the best selectivity against hCA IX and hCA XII isoforms over off-target hCA II, with selectivity indexes ranging from 5 to 14.

Dynamics of an inhibitor at and away from an out-of-active site binding location in human carbonic anhydrase II

The high resolution crystal structure of 2-[(S)-benzylsulfinyl]benzoic acid (3G1)-bound human carbonic anhydrase (HCA) II shows the ligand molecule bound in an out-of-active-site pocket on the surface of HCA II. At this location, it is expected to inhibit the enzyme by arresting the His-64 mediated proton shuttle in its catalytically unimportant outward orientation. However, 3G1 is known to act as a weak inhibitor of HCA II. In this article, we have used computer simulation studies to examine the dynamics of 3G1 molecule for 1μs during its long residence in the binding pocket. We have also evaluated the free energy and kinetics of its fast unbinding to the bulk solvent as the 3G1 molecule crosses the bottleneck at the mouth of the binding pocket. Our analysis demonstrates how the dynamical fluctuations around the binding site and unbinding to the bulk solvent render the 3G1 molecule a weak inhibitor of HCA II.