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A series of 1,2,3-triazol-1-ylbenzenesulfonamide derivatives was designed, synthesized and their ability to inhibit several carbonic anhydrase isoforms was evaluated. The basis of our design is to hybridize the benzenesulfonamide moiety widely used as a zinc-binding group, a triazole ring as spacer with a tail of different substituted aryl moieties. The synthesis of these compounds was achieved using Cu(I)-mediated click chemistry between the azide containing the benzenesulfonamide pharmacophore and various aryl acetylenes or 1,6-heptadiyne through copper-catalyzed [3+2] cycloaddition reaction. The ability the new derivatives to inhibit four human carbonic anhydrase isoforms hCA I, II, IX, and XII was evaluated. All the compounds exhibited good potency and high selectivity towards isoforms hCA I and II more than isoforms hCA IX and XII, especially for the derivatives 3c and 3j that displayed K

Carbonic anhydrases (CAs, Enzyme Commission 4.2.1.1) convert carbon dioxide to bicarbonate in metabolism and use Zn

Carbonic anhydrase IX (CA IX), a tumor-associated metalloenzyme, represents a validated target for cancer therapy and diagnostics. Herein, we report the inhibition properties of isomeric families of sulfonamidopropyl-dicarba-closo-dodecaboranes group(s) prepared using a new direct five-step synthesis from the corresponding parent cages. The protocol offers a reliable solution for synthesis of singly and doubly substituted dicarba-closo-dodecaboranes with a different geometric position of carbon atoms. The closo-compounds from the ortho- and meta-series were then degraded to corresponding 11-vertex dicarba-nido-undecaborate(1-) anions. All compounds show in vitro enzymatic activity against CA IX in the low nanomolar or subnanomolar range. This is accompanied by clear isomer dependence of the inhibition constant (Ki ) and selectivity towards CA IX. Decreasing trends in Ki and selectivity index (SI ) values are observed with increasing separation of the cage carbon atoms. Interactions of compounds with the active sites of CA IX were explored with X-ray crystallography, and eight high-resolution crystal structures uncovered the structural basis of inhibition potency and selectivity.

In this study, 22 novel compounds were designed and synthesized by acetamide bridge chains, among which 5 a-5 k were monosubstituted compounds, and 6 a-6 k were disubstituted. A series of biological evaluations was then carried out to determine the carbonic anhydrase inhibitory activity, neuroprotective effects and cytotoxicity of 5 a-5 k and 6 a-6 k. The results showed that some compounds could protect PC12 cells from sodium nitroprusside (SNP)-induced damage. In terms of the neuroprotection and inhibitory activity against carbonic anhydrase II, monosubstituted compounds were better than disubstituted. Compound 5 c exhibited better protective effect in PC12 cells than that of edaravone, and 5 c also showed less cytotoxicity. In addition, compound 5 c was found to be the most effective selective carbonic anhydrase II inhibitor (IC50 =16.7 nM, CAI/CAII=54.3), which was similar to the inhibitory effect of acetazolamide. Moreover, the selectivity of compound 5 c was better than that of acetazolamide (IC50 =12.0 nM, CAI/CAII=20.8). Molecular docking presented that the binding effect of compound 5 c with carbonic anhydrase II was superior to that of 5 c with carbonic anhydrase I and IX, which was consistent with the inhibitory results. Based on above findings, compound 5 c may be a potential candidate for selective carbonic anhydrase II inhibitor, and it had obviously neuroprotective effect and great advantages in drug safety.

In this research, a series of N-phenylsulfonamide derivatives (1-12) were designed, synthesized, and investigated for their inhibitory potencies against carbonic anhydrase isoenzymes I, II, and IX (hCA I, hCA II, and hCA IX) and cholinesterases (ChE), namely, acetylcholinesterase and butyrylcholinesterase. These compounds, whose inhibition potentials were evaluated for the first time, were characterized by spectroscopic techniques (H-1- and C-13-NMR and FT-IR). CA isoenzyme inhibitors are significant therapeutic targets, especially owing to their preventive/activation potential in the therapy processes of some diseases such as cancer, osteoporosis, and glaucoma. On the other hand, Cholinesterase inhibitors are valuable molecules with biological importance that can be employed in the therapy process of Alzheimer's patients. The results showed that the tested molecules had enzyme inhibition activities ranging from 9.7 to 93.7 nM against these five metabolic enzymes. Among the tested molecules, the methoxy and the hydroxyl group-containing compounds 10, 11, and 12 exhibited more enzyme inhibition activities when compared to standard compounds acetazolamide, sulfapyridine, and sulfadiazine for CA isoenzymes and neostigmine for ChE, respectively. Of these three molecules, compound 12, which had a hydroxyl group in the para position in the aromatic ring, was determined to be the most active molecule against all enzymes. In silico work, molecular docking has also shown similar results and is consistent with the experimental data in the study. As a result, we can say that some of the tested molecules might be used as promising inhibitor candidates for further studies on this topic.

Twenty novel 1,2,3-triazole benzenesulfonamides featuring nitrile 8a-g, carbothioamide 9a-f, and N'-hydroxycarboximidamide 10a-g functionalities were designed and synthesized to improve potency and selectivity as carbonic anhydrase inhibitors (CAIs). The synthesized 1,2,3-triazole compounds were tested in vitro as CAIs against four physiologically and pharmacologically relevant isoforms of human carbonic anhydrase (hCA I, II, IV, and IX). Compounds 8a-g, 9a-f, and 10a-g displayed variable inhibition constants ranging from 8.1 nM to 3.22 μM for hCA I, 4.7 nM to 0.50 μM for hCA II, 15.0 nM to 3.7 μM for hCA IV, and 29.6 nM to 0.27 μM for hCA IX. As per the inhibition data profile, compounds 9a-e exhibited strong efficacy for hCA IV, whereas the inhibition was found to be somewhat diminished in the case of hCA IX by nearly all the compounds. A computational protocol based on docking and MM-GBSA was conducted to reveal the plausible interactions of the targeted sulfonamides within the hCA II and IX binding sites. The outcomes of appending various functionalities at the C-4 position of the 1,2,3-triazole motif over the inhibition potential and selectivity of the designed sulfonamides were examined with a potential for the discovery of new isoform selective CAIs. The CAI and SAR data established the significance of the synthesized 1,2,3-triazoles as building blocks for developing CAI drugs.

A series of some naphthol derivatives 4a-f, 5a,f, 6a, and 7a,b (six novel ones: 4c,d, 5a, 6a, 7a,b) bearing F, Cl, Br, OMe, and dioxole substituents at different positions of the aromatic rings was designed, synthesized, and characterized. The naphthol derivatives were synthesized in three steps, namely the addition reaction of furan via Diels-Alder cycloaddition reaction, copper(II) trifluoromethanesulfonate (Cu(OTf)2 )-catalyzed aromatization reaction, and the bromination reaction, respectively. The structures of the newly obtained compounds (4c,d, 5a, 6a, 7a,b) were characterized by spectroscopic techniques. In addition, some biological activity studies were investigated under in vitro conditions. Inhibition studies of these compounds were performed on human carbonic anhydrase (hCA) I and II isoenzymes purified from human erythrocytes as a biological evaluation. Moreover, their potential antioxidant and antiradical activities were studied by analytical methods like ABTS•+ and DPPH• scavenging, and it was determined that some molecules showed good activity. Also, inhibition of acetylcholinesterase (AChE), which is a marker of many degenerative neurological diseases, was tested and the results were discussed. Excellent enzyme inhibition results were recorded for most of the molecules. These 1-naphthol derivatives were found as effective inhibitors for hCA I, hCA II, and AChE with K i values ranging from 0.034 ± 0.54 to 0.724 ± 0.18 µM for hCA I, 0.172 ± 0.02 to 0.562 ± 0.21 µM for hCA II, and 0.096 ± 0.01 to 0.177 ± 0.02 µM for AChE.

A series of fluoroalkylated cyclic λ3 -iodanes and their hydrochloride salts was prepared and used in a combination with sodium ascorbate in buffer or aqueous methanol mixtures for radical fluoroalkylation of a range of substituted indoles, pyrroles, tryptophan or its derivatives, and Trp residues in peptides. As demonstrated on several peptides, the aromatic amino acid residues of Trp, Tyr, Phe, and His are targeted with high selectivity to Trp. The functionalization method is biocompatible, mild, rapid, and transition-metal-free. The proteins myoglobin, ubiquitin, and human carbonic anhydrase I were also successfully functionalized.

We report results showing that the silencing of carbonic anhydrase I (siCA1) in prostatic (PC3) tumour cells has a significant impact on exosome formation. An increased diameter, concentration and diversity of the produced exosomes were noticed as a consequence of this knock‐down. The protein composition of the exosomes' cargo was also altered. Liquid chromatography and mass spectrometry analyses identified 42 proteins significantly altered in PC3 siCA1 exosomes compared with controls. The affected proteins are mainly involved in metabolic processes, biogenesis, cell component organization and defense/immunity. Interestingly, almost all of them have been described as ‘enhancers' of tumour development through the promotion of cell proliferation, migration and invasion. Thus, our results indicate that the reduced expression of the CA1 protein enhances the malignant potential of PC3 cells.

Carbonic anhydrase (CA) enzymes are involved in many physiological events. These enzymes, which contain Zn

This paper presents experimental and molecular docking studies on the inhibitory effects of tyrosol, hydroxytyrosol, luteolin, diosmetin, caffeic acid, luteolin 7-O-glycoside, and apigenin 7-O-glycoside from olive (Olea europaea L.) leaf against human carbonic anhydrase (hCA, E.C.4.2.1.1) isozymes I and II. After these isozymes were separately purified, their activities were determined using the esterase activity. IC50 values for hCA I and II were calculated as 2.02-11.38 mu M and 2.23-9.05 mu M, respectively. The compounds were identified as CA inhibitors, with K-i values in the ranges of 1.66-9.17 mu M for the hCA I isozyme and 1.49-14.21 mu M for hCA II. The inhibitory effects of these natural compounds were also compared to acetazolamide, which is a potent inhibitor of both CA isozymes. Our results may contribute to the synthesis of new CA inhibitors and pave the way for new drug design in the treatment of a number of diseases including cancer, obesity, diabetes, and glaucoma.

In the present study, coumarin-bearing three pyridinium and three tetra-alkyl ammonium salts were synthesized. The compounds were fully characterized by 1 H- and 13 C-NMR, LC/MS and IR spectroscopic methods and elemental analyses. The cytotoxic properties of all compounds were tested against human liver cancer (HepG2), human colorectal cancer (Caco-2) and non-cancer mouse fibroblast (L-929) cell lines. Some compounds performed comparable cytotoxicity with standard drug cisplatin. Antibacterial properties of the compounds were tested against Gram-negative Escherichia coli and Gram-positive Bacillus subtilis bacteria, but the compounds did not have any antibacterial effect against both bacteria. Enzyme inhibitory properties of all compounds were tested on the activities of human carbonic anhydrase I and II, and xanthine oxidase. All compounds inhibited both enzymes more effectively than standard drugs, acetazolamide and allopurinol, respectively. The biological evaluation results showed that ionic and water soluble coumarin derivatives are promising structures for further investigations especially on enzyme inhibition field.

Gencer, Nahit/0000-0001-7092-8857; WOS: 000422674700030 A series of novel tetrahydroquinoline derivatives containing urea moiety was synthesized and their invitro inhibitory effects on the human carbonic anhydrase isoenzymes (hCA-I and hCA-II) were evaluated by using the CO2 hydration method. All the synthesized compounds exhibited inhibitory activity against both hCA I and hCA II with 1-(4-fluorophenyl)-3-(4-(4-p-tolyl-5,6,7,8-tetrahydroquinolin-2-yl)phenyl)urea (7k, IC50 value of 5.28M and 5.51M, against hCA I and hCA II, respectively) as the strongest inhibitor in this study. Structure-activity relationships were also investigated. The results showed that most of synthesized compounds have a higher inhibitory activity against hCA I than hCA II. Also the substituents, containing two or more pairs of non-bonding electrons, generally increased the hCA I and II inhibitory activity. Furthermore, some electronic parameters such as the highest occupied molecular orbital and the lowest unoccupied molecular orbital (HOMO-LUMO) energy levels, electron affinity, total energy and dipole moments of the best inhibitors (7b, 7h and 7k) in this study were also calculated by using Gaussian software. The results revealed that HOMO-LUMO energy differences, total energy, chemical hardness and dipole moment of 7b, 7h and 7k showed a linear relationship with increasing inhibitory activity. Gaziosmanpasa University Scientific Research ProjectGaziosmanpasa University [2011/34] This work was supported by Gaziosmanpasa University Scientific Research Project (Project No: 2011/34).

Ataturk University BAP office, In this study, 4-[5-aryl-3-(thiophen-2-yl)-4,5-dihydro-1H-pyrazol-1-yl] benzenesulfonamides were synthesized, and inhibition effects on AChE, hCA I, and hCA II were evaluated. K-i values of the compounds toward hCA I were in the range of 24.2 +/- 4.6-49.8 +/- 12.8nm, while they were in the range of 37.3 +/- 9.0-65.3 +/- 16.7nm toward hCA II. K-i values of the acetazolamide were 282.1 +/- 19.7nm and 103.60 +/- 27.6nm toward both isoenzymes, respectively. The compounds inhibited AChE with K-i in the range of 22.7 +/- 10.3-109.1 +/- 27.0nm, whereas the tacrine had K-i value of 66.5 +/- 13.8nm. Electronic structure calculations at M06-L/6-31+G(d,p)//AM1 level and molecular docking studies were also performed to enlighten inhibition mechanism and to support experimental findings. Results obtained from calculations of molecular properties showed that the compounds obey drug-likeness properties. The experimental and computational findings obtained in this study might be useful in the design of novel inhibitors against hCA I, hCA II, and AChE.

Six new monopeptides, seven new dipeptides, and two deprotected monopeptide dihydroquinolinone conjugates were prepared by the benzothiazole-mediated method and their structures were confirmed by nuclear magnetic resonance, mass, infrared spectroscopy, and elemental analysis methods. The human carbonic anhydrase (hCA) I and hCA II enzyme inhibition activities of the compounds were determined using the stopped-flow instrument. The synthesized peptide-dihydroquinolinone conjugates 2, 3, 6, 10, 13, and 15 showed inhibition against the hCA II enzyme in the range of 15.7-65.7 µM. However, none of the compounds showed inhibition of hCA I at a concentration of 100 µM. The antioxidant activities of the compounds were also examined using the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging method at concentrations of 12.5-125 µg/ml, but when compared with the standard antioxidant compounds α-tocopherol and butylated hydroxyanisole (BHA), weak antioxidant activities were detected. The cytotoxic effects of four compounds against the A549 and BEAS-2B cell lines were also investigated. Among the compounds studied, compound 7 was found to be most effective, with the IC50 values on the A549 cells for 48 and 72 h being 26.87 and 9.979 µg/ml, respectively, and the IC50 values on the BEAS-2B cells being >100 µg/ml. None of the tested compounds showed antimicrobial activity in the concentration range (800-1.56 µg/ml) studied.

In this study, 23 different imidazole derivatives were synthesized, and the inhibitory properties of these derivatives against carbonic anhydrase I and II isoenzymes were investigated for the first time. The inhibition concentrations of the imidazole derivatives were found to be in the range of 2.89-115.5 nM. Docking studies examined the binding properties of the imidazole derivatives, and the structure-activity relationship is discussed. Theoretical calculations showed that the binding mode of the imidazole ring was non-zinc binding.

In this work, the inhibitory activity of Voriconazole was measured against some metabolic enzymes, including human carbonic anhydrase (hCA) I and II isoenzymes, acetylcholinesterase (AChE), and α-glycosidase; the results were compared with standard compounds including acetazolamide, tacrine, and acarbose. Half maximal inhibition concentration (IC50 ) values were obtained from the enzyme activity (%)-[Voriconazole] graphs, whereas Ki values were calculated from the Lineweaver-Burk graphs. According to the results, the IC50 value of Voriconazole was 40.77 nM for α-glycosidase, while the mean inhibition constant (Ki ) value was 17.47 ± 1.51 nM for α-glycosidase. The results make an important contribution to drug design and have pharmacological applications. In addition, the Voriconazole compound demonstrated excellent inhibitory effects against AChE and hCA isoforms I and II. Voriconazole had Ki values of 29.13 ± 3.57 nM against hCA I, 15.92 ± 1.90 nM against hCA II, and 10.50 ± 2.46 nM against AChE.

PubMed ID: 30537031 Novel substituted thiophene derivatives (1, 2a-e, 3, and 4) were synthesized and their structures were characterized by infrared radiation, nuclear magnetic resonance, and mass analysis. These novel substituted thiophene derivatives were effective inhibitor compounds of the carbonic anhydrase I and II isozymes (hCA I and II), and acetylcholinesterase (AChE) enzyme with K i values in the range of 447.28 to 1004.65 nM for hCA I, 309.44 to 935.93 nM for hCA II, and 0.28 to 4.01 nM for AChE, respectively. Novel substituted thiophene derivatives can be good candidate drugs for the treatment of some diseases like neurological disorders, epilepsy, glaucoma, gastric and duodenal ulcers, mountain sickness, or osteoporosis as carbonic anhydrase isozymes inhibitors, and for the treatment of Alzheimer’s and Parkinson’s diseases as acetylcholinesterase inhibitors. © 2018 Wiley Periodicals, Inc.

[Abstract Not Available]

WOS: 000467327900002 PubMed ID: 30811749 Human carbonic anhydrase I and II isoenzymes (hCA I and II) and acetylcholinesterase (AChE) are important metabolic enzymes that are closely associated with various physiological and pathological processes. In this study, we investigated the inhibition effects of some sulfonamides on hCA I, hCA II, and AChE enzymes. Both hCA isoenzymes were purified by Sepharose-4B-L-Tyrosine-5-amino-2-methylbenzenesulfonamide affinity column chromatography with 1393.44 and 1223.09-folds, respectively. Also, some inhibition parameters including IC50 and K-i values were determined. Sulfonamide compounds showed IC50 values of in the range of 55.14 to 562.62 nM against hCA I, 55.99 to 261.96 nM against hCA II, and 98.65 to 283.31 nM against AChE. K-i values were in the range of 23.40 +/- 9.10 to 365.35 +/- 24.42 nM against hCA I, 45.87 +/- 5.04 to 230.08 +/- 92.23 nM against hCA II, and 16.00 +/- 45.53 to 157.00 +/- 4.02 nM against AChE. As a result, sulfonamides had potent inhibition effects on these enzymes. Therefore, we believe that these results may contribute to the development of new drugs particularly in the treatment of some disorders.

Spontaneous tumour regression after high‐dose therapy and autologous stem cell transplantation is associated with the aplastic anaemia‐like syndrome and the presence of polyclonal autoantibodies against carbonic anhydrase I (CA I). When tumour cells were grown in vitro in the presence of patients’ sera positive for anti‐CA I autoantibodies, their morphological pattern was altered. These changes were accompanied by modifications in the gene expression profile. We observed downregulation of genes of the basal lamina assembly (collagen type IV alpha 4, the laminin subunit gamma 2), the extracellular matrix (collagen type I alpha 1), the cytoskeleton (keratin 14 type I), the collagen triple helix repeat containing 1 and the proto‐oncogene WNT7B. On the other hand, the expression of the CA 1 gene was increased in the tumour cells. It was also noticed that the presence of anti‐CA I autoantibodies did not impair tumour cell proliferation and cell viability in vitro. These findings were observed only in the presence of patients’ sera positive for anti‐CA I autoantibodies.

A number of studies have used global protein profiling technologies on a range of patient samples to detect proteins that are differentially expressed in β-thalassemia/Hb E as an aid for understanding the physiopathology of this disease. Seven studies have identified a total of 111 unique, differentially expressed proteins. Seven proteins (prothrombin, alpha-1-antichymotrypsin, fibrinogen beta chain, hemoglobin beta, selenium-binding protein, microtubule-actin cross-linking factor and adenomatous polyposis coli protein 2) have been identified in two independent studies, whereas two proteins (carbonic anhydrase 1 and peroxiredoxin-2) have been identified in three independent studies. Both of these latter two proteins were consistently upregulated in the studies that identified them. Ontological analysis of all differentially regulated proteins identified "response to inorganic substances" as the most significant functional annotation cluster, which is consistent with iron overload being a major pathological consequence of this disease. Despite the range of samples investigated and the relatively small number of studies undertaken, a coherent picture of the mediators of the pathological consequences of β-thalassemia/Hb E disease is starting to emerge.

A novel series of sulfonamides, 4-(3-phenyltriaz-1-en-1-yl)-N-(4-methyl-2-pyrimidinyl)benzenesulfonamides (1-9), was designed and synthesized by the diazo reaction between sulfamerazine and substituted aromatic amines for the first time. Their chemical structures were characterized by 1 H nuclear magnetic resonance (NMR), 13 C NMR, and high-resolution mass spectra. The newly synthesized compounds were evaluated in terms of acetylcholineasterase (AChE) and human carbonic anhydrases (hCA) I and II isoenzymes inhibitory activities. According to the AChE inhibition results, the Ki values of the compounds 1-9 were in the range of 19.9 ± 1.5 to 96.5 ± 20.7 nM against AChE. Tacrine was used as the reference drug and its Ki value was 49.2 ± 2.7 nM against AChE. The Ki values of the compounds 1-9 were in the range of 10.2 ± 2.6 to 101.4 ± 27.8 nM against hCA I, whereas they were 18.3 ± 4.4 to 48.1 ± 4.5 nM against hCA II. Acetazolamide was used as a reference drug and its Ki values were 72.2 ± 5.4 and 52.2 ± 5.7 nM against hCA I and hCA II, respectively. The most active compounds, 1 (nonsubstituted) against AChE, 5 (4-ethoxy-substituted) against hCA I, and 8 (4-bromo-substituted) against hCA II, were chosen and docked at the binding sites of these enzymes to explain the inhibitory activities of the series. The newly synthesized compounds presented satisfactory pharmacokinetic properties via the estimation of ADME properties.

Coumarins and their derivatives are receiving increasing attention due to numerous biochemical and pharmacological applications. In this study, a series of novel coumarin–1,2,3-triazole-acetamide hybrids was tested against some metabolic enzymes including α-glycosidase (α-Gly), α-amylase (α-Amy), acetylcholinesterase (AChE), butyrylcholinesterase (BChE), human carbonic anhydrase I (hCA I), and hCA II. The new coumarin–1,2,3-triazole-acetamide hybrids showed Ki values in the range of 483.50–1,243.04 nM against hCA I, 508.55–1,284.36 nM against hCA II, 24.85–132.85 nM against AChE, 27.17–1,104.36 nM against BChE, 590.42–1,104.36 nM against α-Gly, and 55.38–128.63 nM against α-Amy. The novel coumarin–1,2,3-triazole-acetamide hybrids had effective inhibition profiles against all tested metabolic enzymes. Also, due to the enzyme inhibitory effects of the new hybrids, they are potential drug candidates to treat diseases such as epilepsy, glaucoma, type-2 diabetes mellitus (T2DM), Alzheimer's disease (AD), and leukemia. Additionally, these inhibition effects were compared with standard enzyme inhibitors like acetazolamide (for hCA I and II), tacrine (for AChE and BChE), and acarbose (for α-Gly and α-Amy). Also, those coumarin–1,2,3-triazole-acetamide hybrids with the best inhibition score were docked into the active site of the indicated metabolic enzymes. © 2020 Deutsche Pharmazeutische Gesellschaft

[Ni(C11H9N2O5)(2)(H2O)(2)]center dot 3(C3H7NO) (1) and [Co(C11H9N2O5)(2)(H2O)(2)]center dot 3(C3H7NO) (2) are synthesized and characterized by elemental analysis, FT-IR spectra, magnetic susceptibility, and thermal analysis. In addition, the crystal structure of Ni(II) complex is presented. Both complexes show distorted octahedral geometry. In 1 and 2, metal ions are coordinated by two oxygen atoms of salicylic residue and two nitrogen atoms of maleic amide residue from two ligands, and two oxygen atoms from two water molecules. In this paper, both compounds showed excellent inhibitory effects against human carbonic anhydrase (hCA) isoforms I, and II, -glycosidase, acetylcholinesterase (AChE), and butyrylcholinesterase (BChE). Compounds 1 and 2 had Ki values of 18.36 +/- 4.38 and 26.61 +/- 7.54 nM against hCA I and 13.81 +/- 3.02 and 29.56 +/- 6.52 nM against hCA II, respectively. On the other hand, their Ki values were found to be 487.45 +/- 54.18 and 453.81 +/- 118.61 nM against AChE and 199.21 +/- 50.35 and 409.41 +/- 6.86 nM against BChE, respectively.

WOS: 000419943200008, PubMed ID: 29131470, Some novel derivatives of thiosemicarbazide and 1,2,4-triazole-3-thiol were synthesized and evaluated for their biological activities. The title compounds were prepared starting from readily available pyridine-2,5-dicarboxylic acid. The reaction carboxylic acid with absolute ethanol afforded the corresponding dimethyl pyridine-2,5-dicarboxylate (1). The reaction of dimethyl-2,5-pyridinedicarboxylate (1) with hydrazine hydrate good yielded pyridine-2,5-dicarbohydrazide (2). Refluxing compound 2 with alkyl/aryl isothiocyanate derivatives for 3-8 h afforded 1,4-disubstituted thiosemicarbazides (3a-e). Base-catalyzed intra-molecular dehydrative cyclization of these intermediates furnished the 4,5-disubstituted bis-mercaptotriazoles (4a-e) in good yield (85%-95%). Among the target compounds, 2,2'-(pyridine-2,5-diyldicarbonyl)bis[N-(p-methoxyphenyl)hydrazinecarbothioamide] (3c) showed very high activity with value of 72.93% against 1,1-diphenyl-2-picrylhydrazyl free radical at the concentration of 25 mu g/mL. The inhibitory effects of the target compounds against acetylcholinesterase (AChE), hCA I, and II were studied. AChE, cytosolic hCA I and II isoforms were potently inhibited by synthesized these derivatives with K(i)s in the range of 3.07 +/- 0.76-87.26 +/- 29.25 nM against AChE, in the range of 1.47 +/- 0.37-10.06 +/- 2.96 nM against hCA I, and in the range of 3.55 +/- 0.57-7.66 +/- 2.06 nM against hCA II, respectively., Bingol University Scientific Research Projects Coordination Unit (BUBAP) [2010-013, BAP136-104-2011], We acknowledge with great pleasure the financial support provided by Bingol University Scientific Research Projects Coordination Unit (BUBAP), project no: 2010-013 and BAP136-104-2011.

In this paper, synephrine and phenylephrine compounds showed excellent inhibitory effects against human carbonic anhydrase (hCA) isoforms I and II, α-amylase, α-glycosidase, acetylcholinesterase (AChE), and butyrylcholinesterase (BChE). Synephrine and phenylephrine had Ki values of 199.02 ± 16.01 and 65.01 ± 5.00 μM against hCA I and 336.02 ± 74.01 and 92.04 ± 18.03 μM against hCA II, respectively. On the other hand, their Ki values were found to be 169.10 ± 80.03 and 88.03 ± 5.01 nM against AChE and 177.06 ± 6.01 and 78.03 ± 3.05 nM against BChE, respectively. α-Amylase and α-glycosidase enzymes were easily inhibited by these compounds. α-Glycosidase inhibitors, generally defined to as starch blockers, are anti-diabetic drugs that help to decrease post comestible blood glucose levels.

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.

WOS: 000408915800013, Carbonic anhydrase (CA; EC 4.2.1.1) is used for remedial purposes for several years, as there is significant focus on expanding more new activators (CAAs) and high affinity inhibitors. Alzheimers disease and other similar ailments such as dementia and vascular dementia with Lewy bodies reduce cholinergic activity in the important areas involved in cognition and memory. Prevalent drugs for the symptomatic therapy of dementia are significant in increasing the associated cholinergic deficiency by inhibiting acetylcholinesterase (AChE). These six-membered carbocycles showed nice inhibitory action against AChE and human carbonic anhydrase (hCA) II and I isoforms. The hCA I, II, and AChE were efficiently inhibited by these molecules, with K-i values in the range of 6.70-35.85nM for hCA I, 18.77-60.84nM for hCA II, and 0.74-4.60 for AChE, respectively.

Three series of imidazolidinium ligands (NHC precursors) substituted with 4-vinylbenzyl, 2-methyl-1,4-benzodioxane, and N-propylphthalimide were synthesized. N-Heterocyclic carbene (NHC) precursors were prepared from N-alkylimidazoline and alkyl halides. The novel NHC precursors were characterized by H-1 NMR, C-13 NMR, FTIR spectroscopy, and elemental analysis techniques. The enzymes inhibition activities of the NHC precursors were investigated against the cytosolic human carbonic anhydrase I and II isoenzymes (hCA I and II) and the acetylcholinesterase (AChE) enzyme. The inhibition parameters (IC50 and K-i values) were calculated by spectrophotometric method. The inhibition constants (K-i) were found to be in the range of 166.65-635.38nM for hCA I, 78.79-246.17nM for hCA II, and 23.42-62.04nM for AChE. Also, the inhibitory effects of the novel synthesized NHCs were compared to acetazolamide as a clinical CA isoenzymes inhibitor and tacrine as a clinical cholinergic enzymes inhibitor.

WOS: 000401253900001, PubMed ID: 27780313, Benzothiazepine compounds have a wide range of applications such as antibacterial, antidepressants, anticonvulsants, antihypertensives, antibiotics, antifungal, hypnotic, enzyme inhibitors, antitumor, anticancer and anti-HIV agents. In this study, the synthesis of novel tetralone-based benzothiazepine derivatives (1-16) and their in vitro antibacterial activity and human carbonic anhydrase isoenzymes I and II ( hCA I and II) inhibitory effects were investigated. Both isoenzymes were purified by sepharose-4B-L-tyrosine-sulfanilamide affinity chromatography from fresh human red blood cells. All compounds demonstrated the low nanomolar inhibitory effects on both isoenzymes using esterase activity. Benzothiazepine derivative 2 demonstrated the best hCA I inhibitory effect with Ki value of 18.19 nM. Also, benzothiazepine derivative 7 showed the best hCA II inhibitory effect with Ki value of 11.31 nM. On the other hand, acetazolamide clinically used as CA inhibitor, showed Ki value of 19.92 nM against hCA I and 33.60 nM against hCA II, respectively., Gaziosmanpasa University, Scientific Research Projects Commission [BAP2014/33]; King Saud University, Contract Grant Sponsor: Gaziosmanpasa University, Scientific Research Projects Commission.; Contract Grant Number: BAP2014/33.; Contract Grant Sponsor: King Saud University.

WOS: 000408915800006, PubMed ID: 28544359, Compounds containing nitrogen and sulfur atoms can be widely used in various fields, including industry, medicine, biotechnology, and chemical technology. Among them, amides of acids and heterocyclic compounds have an important place. These amides and thiazolidine-4-ones showed good inhibitory action against butyrylcholinesterase (BChE), acetylcholinesterase (AChE), and human carbonic anhydrase isoforms. AChE exists at high concentrations in the brain and red blood cells. BChE is an important enzyme that is plentiful in the liver, and it is released into the blood in a soluble form. They were demonstrated to have effective inhibition profiles with K-i values of 23.76-102.75nM against hCA I, 58.92-136.64nM against hCA II, 1.40-12.86nM against AChE, and 9.82-52.77nM against BChE. On the other hand, acetazolamide showed K-i value of 482.63 +/- 56.20nM against hCA I, and 1019.60 +/- 163.70nM against hCA II. Additionally, Tacrine inhibited AChE and BChE, showing K-i values of 397.03 +/- 31.66 and 210.21 +/- 15.98nM, respectively., King Saud University, S. Alwasel would like to thank the Distinguished Scientist Fellowship Program, King Saud University for their support.

Known and novel derivatives including CO, Br, and OH (benzylic and phenolic), and the corresponding benzylic alcohols of (3,4-dimethoxyphenyl)(2,3,4-dimethoxyphenyl)methanone were synthesized, and their inhibitory effects on the carbonic anhydrase (CA) isoenzymes I and II were investigated. CAs are the metalloenzymes catalyzing the reversible hydration of carbon dioxide (CO2 ) to bicarbonate (HCO3 (-) ). The inhibitory effects of diphenylmethanone derivatives 5-18 were tested on human CA (hCA, EC 4.2.1.1) isoenzymes (hCA I and hCA II) and they inhibited both isoenzymes at micromolar levels. Compounds 5 and 10 were found to be the best inhibitors against both CA isoenzymes. According to our data, compound 10 was the best inhibitor for isoenzyme hCA I (IC50 = 3.48 µM, Ki = 2.19 µM) whereas compound 5 was found to be the best inhibitor for isoenzyme hCA II (IC50 = 1.33 µM, Ki = 2.09 µM). Probably, stable conformations of 5 and 10 are more convenient for interaction with CA isoenzymes than those of the other compounds.

In the presence of chiral organic catalysts, the optically active 4H-chromine was synthesized from the multicomponent condensation of 5,5-dimethylcyclohexane-1,3-dione with malononitrile and methylene-active compound, and the specific angle of rotation of the compounds was determined in the AUTOPOL-III polarimeter and their structures were confirmed by the X-ray spectroscopic analysis method. These optically active 2-amino-4-aryl-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4H-chromen-3-carbonitriles were effective inhibitors of alpha-glycosidase, the cytosolic carbonic anhydrase I and II isoforms (hCA I and II), and acetylcholinesterase (AChE) enzymes with K-i values in the range of 21.33 +/- 1.11 to 40.24 +/- 10.78 mu M for hCA I, 28.91 +/- 6.51 to 59.97 +/- 15.62 mu M for hCA II, 18.16 +/- 3.18 to 66.57 +/- 1.36 mu M for alpha-glycosidase, and 8.68 +/- 0.93 to 102.61 +/- 24.96 mu M for AChE.

GULCIN, Ilhami/0000-0001-5993-1668; AKBABA, Yusuf/0000-0002-7770-0473 WOS: 000320473000003 PubMed: 23649517 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-2methylphenyl)( 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 K-I values were calculated. The K-I values of the novel compounds were measured in the range of 13.7-32.7 mu M for the hCA I isozyme and 0.65-1.26 mu M 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 (K-I: 36.2 mu M), but rather less activity against hCA II. TUBITAK (The Scientific and Technological Research Council of Turkey)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [TBAG-107T348]; Ataturk UniversityAtaturk University We thank TUBITAK (The Scientific and Technological Research Council of Turkey, Project no: TBAG-107T348), Ataturk University for their financial support of this work and A. Bilal Altundas, for linguistic corrections.

Summary Cerebral hyaline astrocytic inclusions have been observed in a subset of patients with early onset epilepsy, brain structural anomalies, and developmental delay, which indicates that it may represent a unique clinicopathologic entity. To further characterize this condition we use proteomics to investigate differentially expressed proteins in epileptic brain tissue from three pediatric epileptic patients with cerebral hyaline astrocytic inclusions, ranging in age from 5–13 years, and compare to brain tissue from two normal controls. Catalase and carbonic anhydrase I both exhibited increased expression in epileptic brain tissue compared to controls. These findings were confirmed by Western blot analysis. Furthermore, both proteins were localized to astrocytes and in epileptic brain were located within the cerebral hyaline astrocytic inclusions, suggesting a potential role in the generation of this pathologic feature of early onset epilepsy with cerebral hyaline astrocytic inclusions.

Inhibition of two human cytosolic carbonic anhydrase (hCA, EC 4.2.1.1) isozymes I and II with some natural phenolic derivatives was investigated using the esterase assay with 4-nitrophenyl acetate as substrate. Resveratrol, catechin, silymarin, dobutamin, and curcumin showed K(I) values in the range of 4.47-9.47 mm for hCA I and of 2.86-7.44 μm against hCA II, respectively. These natural product phenols were generally competitive inhibitors with 4-nitrophenylacetate as substrate. Some natural phenols investigated here showed effective hCA II inhibitory effects, in the same range as the clinically used sulfonamide acetazolamide, and might be used as leads for generating enzyme inhibitors possibly targeting other CA isoforms that have not been yet assayed for their interactions with such agents.

In the presence of trifluoroacetic acid, on the basis of three-component condensation of phenylthiourea with its salicylaldehyde and methyl-3-oxobutanoate, an efficient method for the synthesis of 1-(4-(2-hydroxyphenyl)-6-methyl-1-phenyl-2-thioxo-1,2,3,4-tetrahydropyrimidin-5-yl)ethanone (I) has been worked out. These novel N-substituted tetrahydropyrimidines based on phenylthiourea showed good inhibitory action against acetylcholinesterase (AChE), alpha-glycosidase, and human carbonic anhydrase (hCA) isoforms I and II. K-i values of AChE enzyme were in the range of 0.48 to 7.46 nM. The hCA I and II were effectively inhibited by the compounds, with K-i values in the range of 502.44 to 923.11 nM for hCA I and 400.32 to 801.57 nM for hCA II, respectively. The antioxidant activity of the novel N-substituted tetrahydropyrimidines based on phenylthiourea was investigated by using different in vitro antioxidant assays; including 1,1-diphenyl-2-picrylhydrazyl (DPPH center dot) radical scavenging, Cu2+ and Fe3+ reducing activities.

Sulfamates have a large spectrum of biological activities including enzyme inhibition. Eight sulfamates derived from menthol (2a-h) were synthesized. Also, in the other section of this study, novel sulfamate derivatives of menthol were tested against some metabolic enzymes including acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and carbonic anhydrase I and II enzymes (hCAs I and II). The newly synthesized novel menthol sulfamate and menthol carbonyl sulfamate derivatives showed K-i values in the range of 34.37 +/- 8.17 to 53.40 +/- 10.61 nM against hCA I, 12.91 +/- 4.57 to 38.67 +/- 6.22 nM against hCA II, 111.17 +/- 52.36 to 522.86 +/- 120.08 nM against AChE, and 50.01 +/- 11.73 to 109.63 +/- 50.08 nM against BChE. As a result, the novel menthol sulfamate and menthol carbonyl sulfamate derivatives can be promising Alzheimer's disease drug candidates and novel hCA I and hCA II enzymes inhibitors.

A series of sulfamides were synthesized and evaluated for their acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and carbonic anhydrase inhibition properties. The synthesis of sulfamides was achieved by the reactions of phenethylamines with N,N-dimethylsulfamoyl chloride in the presence of Et3N. The methoxylated sulfamides were converted into their phenolic derivatives with BBr3 for structure-activity relationships. The synthesized sulfamide/phenolic sulfamide derivatives were investigated as cholinesterase inhibitors and their relative role in AChE versus BChE inhibition was defined. Sulfamide/phenolic sulfamide derivatives are known as important carbonic anhydrase inhibitors; therefore, the synthesized compounds were investigated for inhibitory effects on both carbonic anhydrase isoenzymes. Additionally, we evaluated four different enzymes, which were inhibited in the low nanomolar range by these compounds. According to the present studies, for AChE, BChE, and carbonic anhydrase I and II, the ranges of results are recorded as 0.027-0.076nM, 0.075-0.327nM, 0.123-0.678nM, and 0.024-0.688nM, respectively., Ataturk University [BAP 2014/67], Ataturk University, Grant number: BAP 2014/67

Three series of symmetrical Schiff bases were synthesized from 1,2-diaminoethane, 1,3-diaminopropane and 1,4-diaminobutane and substituted benzaldehydes, and reduced by sodium borohydride to the corresponding benzylic diamines 4-6. All of the compounds obtained were characterized using elemental analysis, FT-IR, H-1 NMR, and C-13 NMR spectroscopy. The enzyme inhibitory properties of these compounds were tested and the influence of the alkane chain length and the substituents on the phenyl group on the enzyme inhibition activity were examined. The novel Schiff bases and their amine derivatives (1a-d, 2a-d, 3b-d, 4a-c, 5a-c, 6a, 6c, 6d) were effective inhibitors of the cytosolic carbonic anhydrase I and II isoforms (hCA I and II), and acetylcholinesterase (AChE) with K-i values in the range of 159.43 +/- 30.03 to 563.73 +/- 115.30nM for hCA I, 104.88 +/- 18.44 to 524.32 +/- 95.03nM for hCA II, and 3.95 +/- 0.74 to 30.83 +/- 6.81nM for AChE.

We performed a systematic comparison of three label-free methods for quantitative assessment of binding strengths of proteins interacting with small molecule ligands. The performance of (1) nanoelectrospray ionization mass spectrometry (nESI-MS), (2) surface plasmon resonance (SPR), and (3) isothermal titration calorimetry (ITC) was compared for the determination of dissociation constants (K(D)). The model system studied for this purpose was the human carbonic anhydrase I (hCAI) with eight known and well characterized sulfonamide inhibitors (Krishnamurthy et al., Chem. Rev. 2008, 108: 946-1051). The binding affinities of the inhibitors chosen vary by more than four orders of magnitude e.g., the K(D) value determined for ethoxzolamide by nESI-MS was 5 +/- 1 nM and the K(D) value for sulfanilamide was 145.7 +/- 10.0 microM. The agreement of the determined K(D) values by the three methods investigated was excellent for ethoxzolamide and benzenesulfonamide (variation with experimental error), good for acetazolamide and 4-carboxybenzenesulfonamide (variation by approximately one order of magnitude), but poor for others e.g., sulpiride. The accuracies of the K(D) values are determined, and advantages and drawbacks of the individual methods are discussed. Moreover, we critically evaluate the three examined methods in terms of ease of the measurement, sample consumption, time requirement, and discuss their limitations.

Three isozyme-specific residues in the active site of human carbonic anhydrase I, Va162, His67, and His200, have been changed by site-directed mutagenesis to their counterparts in human carbonic anhydrase II, Asn62, Asn67, and Thr200. A double mutant, containing Asn62 and Asn67, and a triple mutant, containing all three alterations, were also produced. The rates of CO2 hydration and ester hydrolysis catalyzed by these mutants, the inhibition of these enzymes by the anions, SCN−, and I−, and the binding of the sulfonamide inhibitors, dansylamide and MK-417 (a thienothiopyran-2-sulfonamide) have been measured. The results suggest that the effect of His200 in isozyme I is to prolong the lifetime of the enzyme-bicarbonate complex and to increase the pKa, of the catalytic group, a zinc-coordinated water molecule. For isozyme I, Val62 and His67 might interfere with the function of a proton ‘shuttle’ group in the active site, thus maintaining the buffer specificity of a compulsory proton-transfer step. The single mutations have small effects on anion binding. Only the triple mutant has anion-binding properties resembling those of isozyme II. All mutants show altered sulfonamide-binding properties. In particular, the binding specificity is affected. While wild-type isozyme I binds dansylamide 50 times more strongly than MK-417, the triple mutant shows a reversed selectivity and binds MK-417 nearly 50 times more strongly than dansylamide.

The clinicopathological significance of colonic and small-intestinal phenotypes has hitherto remained unclear in gastric cancers. The purpose of the present study was therefore to examine 86 gastric carcinomas histologically and phenotypically using several phenotypic markers, including colon-specific carbonic anhydrase 1 (CA1) and sucrase as small-intestine specific marker. Of 86 gastric cancers, sucrase and CA1 expression was observed in 12 (14.0%) and only in two cases (2.3%), respectively, associated with other intestinal markers such as villin and mucin core protein (MUC)2. In the sucrase cases, expression appeared independent of the stage. However, CA1 expression was observed only in two advanced cases. No association was observed between colonic and small-intestinal phenotypes, and lymph node metastasis and postoperative survival in the advanced gastric cancer cases with intestinal phenotypic expression. Cdx2 appeared to be linked to upregulation of both CA1 and sucrase. In conclusion, the data suggest that colonic phenotype occurs rarely in gastric carcinogenesis. Colonic and small-intestinal phenotypes appear with expression of several intestinal phenotypic markers under the control of Cdx2 and presumably other related transcription factors.

A molecular platform for protein detection and quantification is reported in which recognition has been integrated with direct monitoring of target-protein binding. The platform is based on a versatile 42-residue helix-loop-helix polypeptide that dimerizes to form four-helix bundles and allows site-selective modification with recognition and reporter elements on the side chains of individually addressable lysine residues. The well-characterized interaction between the model target-protein carbonic anhydrase and its inhibitor benzenesulfonamide was used for a proof-of-concept demonstration. An affinity array was designed where benzenesulfonamide derivatives with aliphatic or oligoglycine spacers and a fluorescent dansyl reporter group were introduced into the scaffold. The affinities of the array members for human carbonic anhydrase II (HCAII) were determined by titration with the target protein and were found to be highly affected by the properties of the spacers (dissociation constant Kd=0.02-3 microM). The affinity of HCAII for acetazolamide (Kd=4 nM) was determined in a competition experiment with one of the benzenesulfonamide array members to address the possibility of screening substance libraries for new target-protein binders. Also, successful affinity discrimination between different carbonic anhydrase isozymes highlighted the possibility of performing future isoform-expression profiling. Our platform is predicted to become a flexible tool for a variety of biosensor and protein-microarray applications within biochemistry, diagnostics and pharmaceutical chemistry.

Morphological, cytological and transport properties of the integument of Salamandra salamandra were investigated during natural ontogenetic development, from birth to adult. Three stages were operationally defined: I, larvae, from birth to metamorphosis; II, metamorphosis (judged externally by the colour change and loss of the gills); and III, post-metamorphosis to adult. Pieces of skin were fixed at various stages for immunocytochemical examinations, and the electrical properties were investigated on parallel pieces. Distinct cellular changes take place in the skin during metamorphosis, and lectin (PNA, WGA and ConA) binding indicates profound changes in glycoprotein composition of cell membranes, following metamorphosis. Band 3 and carbonic anhydrase I (CA I) were confined to mitochondria-rich (MR)-like cells, and were detected only in the larval stage. CA II on the other hand, was detected both in MR-like and in MR cells following metamorphosis. The electrical studies show that the skin becomes more tight (transepithelial resistance increases) upon metamorphosis, followed by manifestation of amiloride-sensitive short-circuit current (I(SC)) indicating that functional Na+ uptake has been acquired. The skin of metamorphosed adults had no finite transepithelial Cl- conductance, and band 3 was not detected in its MR cells. The functional properties of MR-like and MR cells remain to be established.

Three series of imidazolidinium ligands (NHC precursors) substituted with 4-vinylbenzyl, 2-methyl-1,4-benzodioxane, and N-propylphthalimide were synthesized. N-Heterocyclic carbene (NHC) precursors were prepared from N-alkylimidazoline and alkyl halides. The novel NHC precursors were characterized by 1H NMR, 13C NMR, FTIR spectroscopy, and elemental analysis techniques. The enzymes inhibition activities of the NHC precursors were investigated against the cytosolic human carbonic anhydrase I and II isoenzymes (hCA I and II) and the acetylcholinesterase (AChE) enzyme. The inhibition parameters (IC50 and Ki values) were calculated by spectrophotometric method. The inhibition constants (Ki) were found to be in the range of 166.65–635.38 nM for hCA I, 78.79–246.17 nM for hCA II, and 23.42–62.04 nM for AChE. Also, the inhibitory effects of the novel synthesized NHCs were compared to acetazolamide as a clinical CA isoenzymes inhibitor and tacrine as a clinical cholinergic enzymes inhibitor.

Carbonic anhydrases (CAs, E.C.4.2.1.1) play a critical role in many important physiological events and treatment of some diseases. Flavonoids or phenolic compounds have been discovered as novel CAs inhibitors instead of the traditional sulfonamides, with different binding to CAs, pro-drug activities, and new inhibition mechanisms. Here, we investigated the inhibition effects of some flavonoids including malvin, callistephin, oenin, pelargonin, silychristin, and 1-(4-methoxyphenyl)-2-methyl-3-nitro-1-H-indol-6-ol (ID-8) against hCA I and II, which purified from human erythrocytes by affinity column chromatography. Both hCA isoenzymes were inhibited by flavonoids, with IC50 and Ki values in the range of 2.34 nM to 346.5 μM and 51.01–99.55 μM for hCA I and 86.60–750.00 μM for hCA II, respectively. These results showed that flavonoids especially malvin and oenin effectively inhibited hCA I and II isoenzymes. Hence, they may be used as an effective CA inhibitor in medical applications for treatment of certain diseases such as glaucoma, in the future.