Chromone containing sulfonamides as potent carbonic anhydrase inhibitors

Efficient, rapid, and high-yield synthesis of aryl Schiff base derivatives and their in vitro and in silico inhibition studies of hCA I, hCA II, AChE, and BuChE

This study reports a rapid and efficient synthesis of four novel aryl Schiff base derivatives. Biological activity and molecular modeling studies were conducted to evaluate the inhibitory effects of these compounds on human carbonic anhydrases (hCA) and cholinesterases. The results indicate that the triazole-ring-containing compounds have strong inhibitory effects on hCA I, hCA II, acetylcholinesterase (AChE), and butyrylcholinesterase (BuChE) targets. Besides comparing the Schiff bases synthesized in our study to reference molecules, we conducted in silico investigations to examine how these compounds interact with their targets. Our studies revealed that these compounds can occupy binding sites and establish interactions with crucial residues, thus inhibiting the functions of the targets. These findings have significant implications as they can be utilized to develop more potent compounds for treating the diseases that these target proteins play crucial roles in or to obtain drug precursors with enhanced efficacy.

New chromone derivatives bearing thiazolidine-2,4-dione moiety as potent PTP1B inhibitors: Synthesis and biological activity evaluation

A series of chromone derivatives bearing thiazolidine-2,4-dione moiety (5 ∼ 37) were synthesized and evaluated for their PTP1B inhibitory activity, interaction analysis and effects on insulin pathway in palmitic acid (PA)-induced HepG2 cells. The results showed that all derivatives presented potential PTP1B inhibitory activity with IC50 values of 1.40 ± 0.04 ∼ 16.83 ± 0.54 μM comparing to that of positive control lithocholic acid (IC50: 9.62 ± 0.14 μM). Among them, compound 9 had the strongest PTP1B inhibitory activity with the IC50 value of 1.40 ± 0.04 μM. Inhibition kinetic study revealed that compound 9 was a reversible mixed-type inhibitor against PTP1B. CD spectra results confirmed that compound 9 changed the secondary structure of PTP1B by their interaction. Molecular docking explained the detailed binding between compound 9 and PTP1B. Compound 9 also showed 19-fold of selectivity for PTP1B over TCPTP. Moreover compound 9 could recovery PA-induced insulin resistance by increasing the phosphorylation of IRSI and AKT. CETSA results showed that compound 9 significantly increased the thermal stability of PTP1B.

Carbonic anhydrase, its inhibitors and vascular function

It has been known for some time that Carbonic Anhydrase (CA, EC 4.2.1.1) plays a complex role in vascular function, and in the regulation of vascular tone. Clinically employed CA inhibitors (CAIs) are used primarily to lower intraocular pressure in glaucoma, and also to affect retinal blood flow and oxygen saturation. CAIs have been shown to dilate vessels and increase blood flow in both the cerebral and ocular vasculature. Similar effects of CAIs on vascular function have been observed in the liver, brain and kidney, while vessels in abdominal muscle and the stomach are unaffected. Most of the studies on the vascular effects of CAIs have been focused on the cerebral and ocular vasculatures, and in particular the retinal vasculature, where vasodilation of its vessels, after intravenous infusion of sulfonamide-based CAIs can be easily observed and measured from the fundus of the eye. The mechanism by which CAIs exert their effects on the vasculature is still unclear, but the classic sulfonamide-based inhibitors have been found to directly dilate isolated vessel segments when applied to the extracellular fluid. Modification of the structure of CAI compounds affects their efficacy and potency as vasodilators. CAIs of the coumarin type, which generally are less effective in inhibiting the catalytically dominant isoform hCA II and unable to accept NO, have comparable vasodilatory effects as the primary sulfonamides on pre-contracted retinal arteriolar vessel segments, providing insights into which CA isoforms are involved. Alterations of the lipophilicity of CAI compounds affect their potency as vasodilators, and CAIs that are membrane impermeant do not act as vasodilators of isolated vessel segments. Experiments with CAIs, that shed light on the role of CA in the regulation of vascular tone of vessels, will be discussed in this review. The role of CA in vascular function will be discussed, with specific emphasis on findings with the effects of CA inhibitors (CAI).

Design, synthesis and molecular modelling studies of some pyrazole derivatives as carbonic anhydrase inhibitors

In this study, newly synthesised compounds 6, 8, 10 and other compounds (1-5, 7 and 9) and their inhibitory properties against the human isoforms hCA I and hCA II were reported for the first time. Compounds 1-10 showed effective inhibition profiles with KI values in the range of 5.13-16.9 nM for hCA I and of 11.77-67.39 nM against hCA II, respectively. Molecular docking studies were also performed with Glide XP to get insight into the inhibitory activity and to evaluate the binding modes of the synthesised compounds to hCA I and II. More rigorous binding energy calculations using MM-GBSA protocol which agreed well with observed activities were then performed to improve the docking scores. Results of in silico calculations showed that all compounds obey drug likeness properties. The new compounds reported here might be promising lead compounds for the development of new potent inhibitors as alternatives to classical hCA inhibitors.

Synthesis of N-phenylsulfonamide derivatives and investigation of some esterase enzymes inhibiting properties

In this study, synthesis of nine N-phenylsulfonamide derivatives was designed by starting from aniline, which is the simplest aromatic amine. These compounds were obtained in yields between 69 and 95%. Inhibitory properties of synthesized compounds on carbonic anhydrase I (CA I), CA II isoenzymes, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes were investigated. Inhibitors of CA isoenzymes are important therapeutic targets, particularly due to their preventive/activation potential in the treatment of diseases such as edema, glaucoma, cancer and osteoporosis. Cholinesterase inhibitors are valuable compounds that can be used in many different therapeutic applications, including Alzheimer's disease. The compound 8 for CA I, AChE and BChE, 2 for CA II showed a very active inhibition profile (K_I 45.7 ± 0.46 for CA I, 33.5 ± 0.38 nM for CA II, 31.5 ± 0.33 nM for AChE and 24.4 ± 0.29 nM for BChE). The results indicate that these N-phenyl-sulfonamide derivatives are potent CA and cholinesterases and new potential drugs.

Crystal structure of 1-(4-chloro-2-hydroxy-5-iodophenyl)ethan-1-one, C8H6ClIO2

C8H6ClIO2, orthorhombic, Pbcn (no. 60), a = 13.3204(7) Å, b = 7.2517(4) Å, c = 18.5627(9) Å, V = 1793.07(16) Å3, Z = 8, Rgt(F) = 0.0195, wRref(F2) = 0.0483, T = 173 K.

Inhibitory Effects and Kinetic-Docking Studies of Xanthohumol FromHumulus lupulusCones Against Carbonic Anhydrase, Acetylcholinesterase, and Butyrylcholinesterase

Xanthohumol is an essential prenyl flavonoid of Humulus lupulus L. cones, and the taste of beer is due to this compound. Lately, xanthohumol has earned significant interest due to its potential anticancer, antigenotoxic, and adipogenesis effects. In this paper, the inhibitory effects of xanthohumol on human carbonic anhydrase isozymes (hCAI and hCAII), acetylcholinesterase (AChE), and butyrylcholinesterase (BChE) were studied. Also, molecular docking studies were used to investigate ligand interaction diagrams of xanthohumol at the binding cavities of hCAI and II. Xanthohumol was isolated from hop cones by silica gel column chromatography. Carbonic anhydrase enzyme activities were determined spectrophotometrically. In addition, molecular modeling approaches were used for the hCAI and hCAII isoenzymes. Ellman’s method was used for the inhibitor activities of AChE and BChE. The KIvalues of xanthohumol were detected as 0.085 µM for hCAI, 0.049 µM for hCAII, 95.5 nM for AChE, and 124.9 nM for BChE. In conclusion, xanthohumol can pleiotropically exert health promoting effects. It has antiglaucoma, anticonvulsant, antiepileptic, and anticancer activities due to its potent inhibitory effects on hCAI and hCAII. These findings may open new avenues for the design and development of novel hCAI, hCAII, AChE, and BChE inhibitors compared with sulfonamide/sulfamate.

Discovery of curcumin inspired sulfonamide derivatives as a new class of carbonic anhydrase isoforms I, II, IX, and XII inhibitors

A series of curcumin inspired sulfonamide derivatives was prepared from various chalcones and 4-sulfamoyl benzaldehyde via Claisen-Schmidt condensation. All new compounds were assayed as inhibitors of four human isoforms of the metalloenzyme carbonic anhydrase (hCA, EC 4.2.1.1) isoforms hCA I, II, IX and XII. Interesting inhibitory activities were observed against all these isoforms. hCA I, an isoform involved in several eye diseases was inhibited moderately with K_Is in the range of 191.8-904.2 nM, hCA II, an antiglaucoma drug target was highly inhibited by the new sulfonamides, with K_Is in the range of 0.75-8.8 nM. hCA IX, a tumor-associated isoform involved in cancer progression and metastatic spread was potently inhibited by the new sulfonamides, with K_Is in the range of 2.3-87.3 nM, whereas hCA XII, and antiglaucoma and anticancer drug target, was inhibited with K_Is in the range of 6.1-71.8 nM. It is noteworthy that one of the new compounds, 5d, was found to be almost 9 times more selective against hCA II (K_I = 0.89 nM) over hCA IX and hCA XII, whereas 5e was 3 and 70 times more selective against hCA II (K_I = 0.75 nM) over hCA IX and hCA XII, respectively.

Carbonic anhydrase inhibitory properties of some uracil derivatives

Inhibitors of carbonic anhydrase (CA) have been carried out in many therapeutic applications, especially antiglaucoma activity. In this study, we investigated some uracil derivatives (4–12) to inhibit human CA I (hCA I) and II (hCA II) isoenzymes. The K_I values of the compounds 4–12 are in the range of 0.085–428 µM for hCA I and of 0.1715–645 µM against hCA II, respectively. It is concluded from the kinetic investigations, all compounds used in the study act as competitive inhibitors with substrate, 4-NPA. Uracil derivatives are emerging agents for the inhibiton of carbonic anhydrase which could be used in biomedicine.

Synthesis and carbonic anhydrase inhibitory properties of novel chalcone substituted benzenesulfonamides

Carbonic anhydrases (CAs, EC 4.2.1.1) are crucial metalloenzymes involved in many bioprocesses, through catalysis of the reversible hydration/dehydration process of CO2/HCO3-. The inhibition of human CA isoforms I and II with a new series of sulfonamide derivatives incorporating substituted chalcone moieties were studied in this study. All these newly synthesized sulfonamides demonstrated important inhibitory profiles to these CA isoforms with KIs in the range of 9.88 to 55.43nM, making these compounds interesting leads, with potential applications in medicinal chemistry.

Crystal structure of 7-iodo-4-oxo-4H-chromene-3-carbaldehyde

In the title compound, C10H5IO3, an iodinated 3-formyl-chromone derivative, the non-H atoms are essentially coplanar (r.m.s. deviation = 0.0344 Å), with the largest deviation from the least-squares plane [0.101 (3) Å] being found for the formyl O atom. In the crystal, mol-ecules are linked through stacking inter-actions [centroid-centroid distance between the benzene rings = 3.700 (3) Å] and C-H⋯O hydrogen bonds. Halogen bonds between the I atoms at 7-position and the formyl O atoms [I1⋯O3 = 3.056 (2) Å, C6-I1⋯O3 = 173.18 (8)° and I1⋯O3-C10 = 111.12 (18)°] are also formed along [110], resulting in sheets perpendicular to the c axis, constructed by C-H⋯O hydrogen bonds and I⋯O halogen bonds.

Pyridazinone substituted benzenesulfonamides as potent carbonic anhydrase inhibitors

A series of sulfonamide derivatives (2a-l) incorporating substituted pyridazinone moieties were investigated for the inhibition of two human cytosolic carbonic anhydrase isoforms, hCA I and hCA II. All these compounds, together with the clinically used sulfonamide acetazolamide were investigated as inhibitors of the physiologically relevant isozymes I and II. These sulfonamides showed very strong inhibition against all these isoforms with K(I)'s in the range of 0.98-8.5 nM which makes such molecules possible to be used as leads for discovery of novel effective CA inhibitors targeting other isoforms with medicinal chemistry applications.

Carbonic anhydrase inhibitors: Design, synthesis, kinetic, docking and molecular dynamics analysis of novel glycine and phenylalanine sulfonamide derivatives

The inhibition of two human cytosolic carbonic anhydrase isozymes I and II, with some novel glycine and phenylalanine sulfonamide derivatives were investigated. Newly synthesized compounds G1-4 and P1-4 showed effective inhibition profiles with KI values in the range of 14.66-315μM for hCA I and of 18.31-143.8μM against hCA II, respectively. In order to investigate the binding mechanisms of these inhibitors, in silico docking studies were applied. Atomistic molecular dynamic simulations were performed for docking poses which utilize to illustrate the inhibition mechanism of used inhibitors into active site of CAII. These sulfonamide containing compounds generally were competitive inhibitors with 4-nitrophenylacetate as substrate. Some investigated compounds here showed effective hCA II inhibitory effects, in the same range as the clinically used sulfonamide, sulfanilamide or mafenide and might be used as leads for generating enzyme inhibitors possibly targeting other CA isoforms which have not been yet assayed for their interactions with such agents.

Interaction of carbonic anhydrase isozymes I, II, and IX with some pyridine and phenol hydrazinecarbothioamide derivatives

A series of hydrazinecarbothioamide derivatives incorporating ethyl, phenyl, tolyl, benzyl, and allyl moieties were prepared and tested as possible inhibitors of three members of the pH regulatory enzyme family, carbonic anhydrase (CA; EC 4.2.1.1). The inhibitory and activatory potencies of the compounds against the cytosolic human isoforms hCA I and hCA II and the transmembrane, tumor-associated hCA IX were analyzed by a hydrase assay with CO2 as substrate, and the inhibition constants (KI) were calculated. Most compounds investigated here exhibited nanomolar or low micromolar inhibition constants against the three isoenzymes. KI values were in the range of 34.1-871 nM for hCA I and compounds 5-10 showed interesting activation of the hCA II with KA value of 0.81-12.5 μM. Compounds 11-16 exhibited moderate inhibition effects on hCA IX in the range of 0.317-1.245 μM but they were less effective for hCA II. Tested compounds were also investigated using in silico applications at the binding pockets of these three targets. The different mechanisms of inhibition by these tested compounds as compared to sulfonamides, and their diverse inhibition profile for these mammalian isozymes, makes this class of derivatives of great interest for the design of novel CA inhibitors.

Discovering novel carbonic anhydrase type IX (CA IX) inhibitors from seven million compounds using virtual screening and in vitro analysis

Carbonic anhydrase type IX (CA IX) enzyme is mostly over expressed in different cancer cell lines and tumor tissues. Potent CA IX inhibitors can be effective for adjusting the pH imbalance in tumor cells. In the present work, we represented the successful application of high throughput virtual screening (HTVS) of large dataset from ZINC database included of ∼7 million compounds to discover novel inhibitors of CA IX. HTVS and molecular docking were performed using consequence Glide/standard precision (SP), extra precision (XP) and induced fit docking (IFD) molecular docking protocols. For each compound, docking code calculates a set of low-energy poses and then exhaustively scans the binding pocket of the target with small compounds. Novel CA IX inhibitor candidates were suggested based on molecular modeling studies and a few of them were tested using in vitro analysis. These compounds were determined as good inhibitors against human CA IX target with Ki in the range of 0.85-1.58 μM. In order to predict the pharmaceutical properties of the selected compounds, ADME (absorption, distribution, metabolism and excretion) analysis was also carried out.

Kinetic and in silico studies of hydroxy-based inhibitors of carbonic anhydrase isoforms I and II

A series of hydroxy and phenolic compounds have been assayed for the inhibition of two physiologically relevant carbonic anhydrase (CA, EC 4.2.1.1) isozymes, the cytosolic human isozymes I and II. The investigated molecules showed inhibition constants in the range of 1.07-4003 and 0.09-31.5 μM at the hCA I and hCA II enzymes, respectively. In order to investigate the binding mechanisms of these inhibitors, in silico studies were also applied. Molecular docking scores of the studied compounds are compared using three different scoring algorithms, namely Glide/SP, Glide/XP and Glide/IFD. In addition, different ADME (absorption, distribution, metabolism and excretion) analysis was performed. All the examined compounds were found within the acceptable range of pharmacokinetic profiles.

Synthesis and determination of some biological activities of novel 2,4-dinitrophenyl derivatives

The antioxidant and radical scavenging activities of the synthesized compounds 3, 5, and 6 were determined by various in vitro assays such as 2,2-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid radical (ABTS(·+) ) scavenging, ferric ion (Fe(3+) ) reducing power and ferrous ion (Fe(2+) ) chelating activities. Moreover, these activities were compared to those of standard antioxidants such as butylated hydroxyanisole, butylated hydroxytoluene, and trolox. The results showed that the new compounds (3, 5, and 6) had potential antioxidant activity. Besides, inhibition of the two human cytosolic carbonic anhydrase (hCA, EC 4.2.1.1) isozymes I and II with some nitrobenzene compounds was investigated. Compounds 1-6 showed Ki values in the range of 4.88-193.4 µM and 5.295-54.75 µM for hCA I and hCA II, respectively.

Synthesis and biological activity of novel thiourea derivatives as carbonic anhydrase inhibitors

A new series of chiral thiourea derivatives (5a-5c) and thiourea containing benzimidazole moieties (9b-9e) were synthesized from different amino acids (l-valine, l-isoleucine, l-methionine, l-phenylalanine, and d-phenylglycine). The compounds were characterized and tested against the two most studied members of the pH regulatory enzyme family, carbonic anhydrase (CA, EC 4.2.1.1). KI values of the novel compounds were measured in the range of 3.4-73.6 μM for hCA I isozyme and 8.7-1.44.2 μM for hCA II isozyme, respectively. Phenol was also tested as standard in order to understand the structure activity relationship and the clinically used sulfonamide acetazolamide was tested for comparison reasons. All of the compounds exhibited competitive inhibition with 4-nitrophenylacetate as substrate.

Inhibition of human carbonic anhydrase isozymes I, II, IX and XII with a new series of sulfonamides incorporating aroylhydrazone-, [1,2,4]triazolo[3,4-b][1,3,4]thiadiazinyl- or 2-(cyanophenylmethylene)-1,3,4-thiadiazol-3(2H)-yl moieties

A series of benzenesulfonamides incorporating aroylhydrazone, piperidinyl, sulfone, [1,2,4]triazolo[3,4-b][1,3,4]thiadiazinyl- or 2-(cyanophenyl-methylene)-1,3,4-thiadiazol-3(2H)-yl moieties was investigated as inhibitors of four α-carbonic anhydrases (CAs, EC 4.2.1.1), the human (h) isoforms hCA I, II (cytosolic, offtarget enzymes) and hCA IX and XII (transmembrane, tumor-associated isoforms). Low nanomolar activity was observed against hCA II (KIs of 0.56-17.1 nM) with these sulfonamides, whereas the slow cytosolic isoform hCA I was less inhibited by these compounds (KIs of 86.4 nM-32.8 µM). Most of these sulfonamides significantly inhibited CA IX, with KIs in the range of 4.5-47.0 nM, although some of the derivatives incorporating bulkier bicyclic moieties, as well as 2-thienyl fragments, showed a weaker activity against this isoform (KIs in the range 50.1-553 nM). All the investigated compounds also inhibited CA XII with KIs in the range 0.85-376 nM. The best inhibitors were those incorporating bulky [1,2,4]triazolo[3,4-b][1,3,4]thiadiazinyl moieties and 1,3,4-thiadiazol-3(2H)-yl groups.

Synthesis and biological evaluation of novel bromophenol derivatives as carbonic anhydrase inhibitors

Here, we provide an alternative synthesis of the natural bromophenol 3,4-dibromo-5-(2,3-dibromo-4,5-dihydroxybenzyl)-6-(ethoxymethyl)benzene-1,2-diol (3) and the first synthesis of (4,5-dihydroxy-2-methylphenyl)(3,4-dihydroxyphenyl)methanone (18) and its brominated derivatives 19-21. The compounds were characterized and tested against the two most studied members of the pH regulatory enzyme family, carbonic anhydrase (CA). The inhibitory potencies of the novel compounds and two natural bromophenols 2, 3 were analyzed at the human isoforms hCA I and hCA II as targets and the KI values were calculated. The KI values of the novel compounds were measured in the range of 13.7-32.7 mM for the hCA I isozyme and 0.65-1.26 mM for the hCA II isozyme. The structurally related compound 14 was also tested in order to understand the structure–activity relationship, and the clinically used sulfonamide acetazolamide (AZA)was tested for comparison reasons. All of the compounds exhibited competitive inhibition with 4-nitrophenylacetate as substrate. The compounds showed strong inhibitory activity against hCA I, being more effective as compared to the clinically used AZA (KI: 36.2 mM), but rather less activity against hCA II.

Synthesis and carbonic anhydrase inhibitory properties of sulfamides structurally related to dopamine

A series of novel sulfamides incorporating the dopamine scaffold were synthesized. Reaction of amines and tert-butyl-alcohol/benzyl alcohol in the presence of chlorosulfonyl isocyanate (CSI) afforded sulfamoyl carbamates, which were converted to the title compounds by treatment with trifluoroacetic acid or by palladium-catalyzed hydrogenolysis. Inhibition of six α-carbonic anhydrases (CAs, EC 4.2.1.1), that is, CA I, CA II, CA VA, CA IX, CA XII and CA XIV, and two β-CAs from Candida glabrata (CgCA) and Mycobacterium tuberculosis (Rv3588) with these sulfamides was investigated. All CA isozymes were inhibited in the low micromolar to nanomolar range by the dopamine sulfamide analogues. K(i)s were in the range of 0.061-1.822 μM for CA I, 1.47-2.94 nM for CA II, 2.25-3.34 μM for CA VA, 0.041-0.37 μM for CA IX, 0.021-1.52 μM for CA XII, 0.007-0.219 μM for CA XIV, 0.35-5.31 μM for CgCA and 0.465-4.29 μM for Rv3588. The synthesized sulfamides may lead to inhibitors targeting medicinally relevant CA isoforms with potential applications as antiepileptic, antiobesity antitumor agents or anti-infective.

QSAR studies of sulfamate and sulfamide inhibitors targeting human carbonic anhydrase isozymes I, II, IX and XII

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.