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ABSTRACT: In the current study, a series of 4-chloromethyl-7-hydroxy-coumarin derivatives containing imidazolium, benzimidazolium, bisbenzimidazolium and quaternary ammonium salts were synthesized, characterized and the inhibition effects of the derivatives on human carbonic anhydrases (hCA I and hCA II) were investigated as in vitro. Structures of these coumarins were confirmed by FT-IR, (1)H NMR, (13)C NMR and LC-MS analyses. Structure activity relationship study showed that 3d (IC50: 79 μM for hCA I and 88 μM for hCA II) performed higher inhibitory activity than others.
Artificial cells, nanomedicine, and biotechnology (Print). 05/2013;
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ABSTRACT: A new series of isoquinoline urea/thiourea derivatives (1-11) were synthesized, and their inhibitory effects on tyrosinase were evaluated. Isoquinoline urea/thiourea derivatives were obtained as a result of the reaction of 5-aminoisoquinoline with isocyanates or isothiocyanates. The result showed that all the synthesized compounds inhibited the tyrosinase enzyme activity. Among the compounds synthesized, 1-(4-chlorophenyl)-3-(isoquinolin-5-yl)thiourea (3) was found to be the most active one (Ki = 119.22 μM), and the inhibition kinetics analyzed using Lineweaver-Burk double reciprocal plots revealed that compound 3 was a competitive inhibitor. We also calculated HOMO-LUMO energy levels, some selected the synthesized compounds (1, 4, 11, 3, 6, 2) using Gaussian software.
Artificial cells, nanomedicine, and biotechnology (Print). 04/2013;
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ABSTRACT: A new series of tetrazole-, oxadiazole- and cyanosubstituted 1,4-dihydropyrimidinone compounds were synthesized, and their inhibitory effects on the activity of purified human carbonic anhydrase (hCA) I were evaluated. 4-Cyanophenyl-1,4-dihydropyrimidinone compounds were prepared with 1,3-diketone, cyanobenzaldehyde and urea. The compounds were reacted with sodium azide and then with anhydride to get the final products. The results showed that all the synthesized compounds inhibited the CA isoenzyme activity. The compound 4-(1,7,7-trimethyl-2,5-dioxo-1,2,3,4,5,6,7,8-octahydroquinazoline-4-yl)benzonitrile 6c (IC(50) = 0.0547 mM) has the most inhibitory effect.
Artificial cells, nanomedicine, and biotechnology (Print). 02/2013;
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ABSTRACT: Abstract 1,3-Dicarbonyl derivatives of methylaminobenzene-sulfonamide were synthesized and their inhibitory effects on the activity of purified human carbonic anhydrase (hCA) I and hCA II were evaluated. hCA I and hCA II from human erythrocytes were purified by a simple one-step procedure by using Sepharose 4B-L-tyrosine-sulfanilamide affinity column. Our results show that the synthesized compounds inhibited the activity of carbonic anhydrase (CA) I and CA II. Among them, 2b and 2e were found to be the most active (IC(50) = 2.12 and 2.52 µM) for hCA I and hCA II, respectively.
Journal of Enzyme Inhibition and Medicinal Chemistry 01/2013; · 1.62 Impact Factor
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ABSTRACT: Abstract In this study, in vitro inhibitory effects of some saccharin derivatives on purified carbonic anhydrase I and II were investigated using CO(2) as a substrate. The results showed that all compounds inhibited the hCA I and hCA II enzyme activities. Among the compounds, 6-(p-tolylthiourenyl) saccharin (6m) was found to be the most active one for hCA I activity (IC(50) = 13.67 μM) and 6-(m-methoxyphenylurenyl) saccharin (6b) was found to be the most active one for hCA II activity (IC(50) = 6.54 μM). Structure-activity relationships (SARs) study showed that, generally, thiourea derivatives (6l--v) inhibited more hCA I and hCA II than urea derivatives (6a-k). All compounds (excluding 6c and 6r) have higher inhibitory activity on hCA II than on hCA I.
Journal of Enzyme Inhibition and Medicinal Chemistry 01/2013; · 1.62 Impact Factor
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ABSTRACT: Paraoxonase (PON) was purified and characterized from the Merino and Kivircik sheep's blood serums by a two-step procedure using ammonium sulphate precipitation and Sepharose-4B-L-tyrosine-1-napthylamine hydrophobic interaction chromatography for the first time. On SDS-polyacyrilamide gel electrophoresis, purified human serum paraoxonase yielded a single band of 66 kDa on SDS-PAGE. The K(M) and V(max) were 0.482 mM and 41.348 U/mL.dak for Merino PON enzyme, 0.153 mM and 70.289 U/mL.dak for Kivircik PON, respectively. The effect of Mn(2+) , Hg(2+) , Co(2+) , Cd(2+) , Ni(2+) and Cu(2+) heavy metals on purified Merino and Kivircik serum PON in vitro was determined.
Artificial Cells Blood Substitutes and Biotechnology (formerly known as Artificial Cells Blood Substitutes and Immobilization Bi 09/2012; · 0.94 Impact Factor
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ABSTRACT: Synthesis of carbazole substituted chalcone urea derivatives and their polyphenol oxidase enzyme activity effects on the diphenolase activity of banana tyrosinase were evaluated. Tyrosinase has been purified from banana on an affinity gel comprised of Sepharose 4B-l-tyrosine-p-aminobenzoic acid. The results showed that most of the compounds (3,4,5a,5d-h) inhibited and some of them (5c,5i-l) activated the tyrosinase enzyme activity. The molecular calculations were performed using Gaussian software for the synthesized compounds to explain the experimental results.
Journal of Enzyme Inhibition and Medicinal Chemistry 07/2012; · 1.62 Impact Factor
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ABSTRACT: Carbazole substituted imines (2a-l) were prepared from N-methyl-3-amino carbazole with different aldehydes. The imines compounds undergo (2+2) cycloaddition reactions with in situ ketenes to produce β-lactam compounds (3a-l). The β-lactam compounds were tested as inhibitors of the xanthine oxidase (XO) purified from bovine milk. The results show that these compounds exhibit inhibitory effects on XO at low concentrations with IC(50) values ranging from 21.65 to 58.04 µM. The most effective compound for XO was 4-(4-chlorophenyl)-1-(9-ethyl-9H-carbazol-3-yl)-3-phenylazetidin-2-one with IC(50) of 21.65 μM. The lactams investigated here showed effective XO inhibitory effects, in the same range as the clinically used allopurinol.
Artificial Cells Blood Substitutes and Biotechnology (formerly known as Artificial Cells Blood Substitutes and Immobilization Bi 06/2012; · 0.94 Impact Factor
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ABSTRACT: The inhibition of polyphenol oxidase (PPO) by glutamic acid was investigated. Application of different concentrations of glutamic
acid to mushroom solution and Ocimum basilicum L. extract showed that glutamic acid appeared to be an effective browning inhibitor. Glutamic acid showed uncompetitive inhibition
for mushroom and Ocimum basilicum L. polyphenol oxidases using 4-methylcatechol as a substrate, for mushroom PPO using catechol as a substrate and for Ocimum basilicum L. polyphenol oxidase using pyrogallol as a substrate; mixed-type inhibition for mushroom polyphenol oxidase using pyrogallol
as a substrate; and non-competitive inhibition for Ocimum basilicum L. polyphenol oxidase using catechol as a substrate. Furthermore, sodium azide was used as an inhibitor for comparison with
the inhibition potency of glutamic acid. It was found that glutamic acid was a more power inhibitor than sodium azide. The
type of inhibition observed depended on the substrate, inhibitor and enzyme source used.
European Food Research and Technology 04/2012; 225(1):67-73. · 1.57 Impact Factor
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ABSTRACT: Peroxidase (EC 1.11.1.7; donor: hydrogen-peroxide oxidoreductase) catalyses the oxidation of various electron donor substrates
(e.g. phenols, aromatic amines). In this study, the peroxidase was extracted from Thymbra spicata L. var. spicata and, then partially purified with (NH4)2SO4 precipitation and dialysis. The substrate specificity of peroxidase was investigated using 2,2′-azino-bis(3-ethylbenz-thiazoline-6-sulfonic
acid) (ABTS), o-dianisidine, o-phenylenediamine, catechol and guaiacol as substrates. Furthermore, the effects of buffer concentration, pH, temperature
and thermal inactivation on enzyme activity were also studied. The results obtained have shown that (i) the best substrate
is o-dianisidine, followed by ABTS, catechol, guaiacol and o-phenylenediamine, respectively; (ii) the best buffer concentration is 40mM for o-dianisidine and catechol, 10mM for ABTS and guaiacol, and 100mM for o-phenylenediamine; (iii) optimum pH is 2.5 for ABTS and o-phenylenediamine, 6.0 for o-dianisidine, and 7.0 for catechol and guaiacol; (iv) optimum temperature is 20°C for catechol, 40°C for ABTS, guaiacol
and o-dianisidine, and 50°C for o-phenylenediamine; and (v) the enzyme activity in the thermal inactivation experiments was enhanced with increase in temperature
with o-dianisidine as a substrate while its activity decreased with o-phenylenediamine.
European Food Research and Technology 04/2012; 225(5):865-871. · 1.57 Impact Factor
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ABSTRACT: A newly series of water-soluble 1-alkyl-3-(4-methyl-7, 8-dihydroxy-2H-chromen-2-one) benzimidazolium chloride salts (3a-j) were synthesized and their inhibitory effects on the activity of purified human carbonic anhydrase (hCA) I and II were evaluated. hCA I and II from human erythrocytes were purified by a simple one step procedure by using Sepharose 4B-L-tyrosine-sulphanilamide affinity column. The result showed that all the synthesized compounds were inhibited the CA isoenzymes activity. Among them, 3g and 3j were found to be most active (IC(50) = 22.09 µM and 20.33 µM) for hCA I and hCA II, respectively.
Journal of Enzyme Inhibition and Medicinal Chemistry 04/2012; · 1.62 Impact Factor
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ABSTRACT: Site-directed mutagenesis has been used to change three amino acid residues involved in the binding of inhibitors (Asn67Ile; Gln92Val and Leu204Ser) within the active site of human carbonic anhydrase (CA, EC 4.2.1.1) II (hCA II). Residues 67, 92 and 204 were changed from hydrophobic to hydrophilic ones, and vice versa. The Asn67Ile and Leu204Ser mutants showed similar k(cat)/K(M) values compared to the wild type (wt) enzyme, whereas the Gln92Val mutant was around 30% less active as a catalyst for CO(2) hydration to bicarbonate compared to the wt protein. Affinity for sulfonamides/sulfamates was decreased in all three mutants compared to wt hCA II. The effect was stronger for the Asn67Ile mutant (the closest residue to the zinc ion), followed by the Gln92Val mutant (residue situated in the middle of the active site) and weakest for the Leu204Ser mutant, an amino acid situated far away from the catalytic metal ion, at the entrance of the cavity. This study shows that small perturbations within the active site architecture have influences on the catalytic efficiency but dramatically change affinity for inhibitors among the CA enzymes, especially when the mutated amino acid residues are nearby the catalytic metal ion.
Bioorganic & medicinal chemistry 02/2012; 20(7):2208-13. · 2.82 Impact Factor
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ABSTRACT: A newly series of 4-(phenylurenyl)chalcone (4a-j) and 4'-(phenylurenyl/thiourenyl)chalcone (9a-l) derivatives were synthesized and their inhibitory effects on the diphenolase activity of banana tyrosinase were evaluated. Tyrosinase has been purified from banana on an affinity gel comprised of Sepharose 4B-l-tyrosine-p-aminobenzoic acid. The result showed that 4a-j inhibited the PPO enzyme activity. Conversely, 9a-h and 9i-l showed activator effect on tyrosinase enzyme activity.
Bioorganic & medicinal chemistry letters 10/2011; 21(24):7479-82. · 2.65 Impact Factor
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ABSTRACT: Serum paraoxonase 1 (EC 3.1.8.1, PON1), a calcium-associated enzyme, has an ability to hydrolyze organophosphate compounds. Related to this property, PON1 has a critical role in antioxidant mechanisms. It is well-known that the enzyme protects LDL from oxidation. In this study we investigated the in vitro inhibitory effects of some drugs. These drugs are oxytocin, dexamethasone, atropine sulphate, gentamicin sulphate, sulfadoxine-trimethoprim, furosemid, metamizole sodium and toldimfos sodium. The IC(50) values obtained varied markedly from 0.014 to 507.72 mg/mL. According to our findings, most potent and significant inhibition was displayed by dexamethasone, atropine sulphate and furosemid.
Journal of Enzyme Inhibition and Medicinal Chemistry 10/2011; 27(5):722-9. · 1.62 Impact Factor
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ABSTRACT: Paraoxonase (PON) is an organophosphate hydrolyser enzyme which also has antioxidant properties in metabolism. Due to its crucial functions, the inhibition of the enzyme is undesirable and very dangerous. PON enzyme activity should not be altered in any case. Inhibitory investigations of this enzyme are therefore important and useful. Metal toxicology of enzymes has become popular in the recent years. Here, we report the in vitro inhibitory effects of some metal ions, including Ni(2+), Cd(2+), Cu(2+) and Hg(2+), on the activity of shark serum PON (SPON). For this purpose, we first purified the enzyme from shark Scyliorhinus canicula (LINNAEUS, 1758) serum and analysed the alterations in the enzyme activity in the presence of metal ions. The K(M) and V(max) is 0.227 mM and 454.545 U/mL, respectively. The results show that metal ions exhibit inhibitory effects on SPON1 at low concentrations with IC(50) values ranging from 0.29 to 2.00 mM. Copper was determined to be the most effective inhibitor with IC(50) of 0.29 mM.
Journal of Enzyme Inhibition and Medicinal Chemistry 09/2011; 27(4):595-8. · 1.62 Impact Factor
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ABSTRACT: A new series of N,N'-diarylureas (1-9) was synthesized. These compounds were investigated as inhibitors of polyphenol oxidase (PPO) which had been purified from banana by an affinity gel comprised of Sepharose 4B-l-tyrosine-p-amino benzoic acid. K(i) values for (1), (2), (3), (5), (6), (7) and (8) were determined as 0.285, 17.97, 0.187, 0.108, 0.063, 0.044 and 0.047 mM, respectively. Thus (2) was by far the most effective inhibitor. Interestingly, (4) and (9) behaved as an activator of PPO in this study.
Journal of Enzyme Inhibition and Medicinal Chemistry 05/2011; 27(1):125-31. · 1.62 Impact Factor
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ABSTRACT: The in vitro effects of the injectable form of analgesic drugs, dexketoprofen trometamol, dexamethasone sodium phosphate, metamizole sodium, diclofenac sodium, thiocolchicoside, on the activity of purified human carbonic anhydrase I and II were evaluated. The effect of these drugs on erythrocyte hCA I and hCA II was compared to recombinant hCA I and hCA II expressed in Ecoli. IC(50) values of the drugs that caused inhibition were determined by means of activity percentage diagrams. The IC(50) concentrations of dexketoprofen trometamol and dexamethasone sodium phosphate on hCA I were 683 μM and 4250 μM and for hCA II 950 μM and 6200 μM respectively. Conversely, the enzyme activity was increased by diflofenac sodium. In addition, thiocolchicoside has not any affect on hCA I and hCA II. The effect of these drugs on erythrocyte hCA I and hCA II were consistent with the inhibition of recombinant enzymes.
Journal of Enzyme Inhibition and Medicinal Chemistry 05/2011; 27(1):37-42. · 1.62 Impact Factor
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ABSTRACT: This is most probably the first time that covalently binding of Human serum paraoxonase 1 (PON1) to superparamagnetic magnetite nanoparticles via carbodiimide activation was investigated and presented in this study. PON1 was purified from human serum using ammonium sulfate precipitation and hydrophobic interaction chromatography (Sepharose 4B, L-tyrosine, 1-Napthylamine) and magnetic iron oxide nanoparticles were prepared by co-precipitation Fe(+2) and Fe(+3) ions in an ammonia solution at room temperature. X-ray diffraction (XRD) and the magnetic measurements showed that the nanoparticles are magnetite and superparamagnetic, respectively. Direct measurements by dynamic light scattering revealed that the hydrodynamic size was 16.76 nm with polydispersity index (PDI: 0.234). The analysis of Fourier transform infrared spectroscopy revealed that the PON1 was properly bound to magnetic nanoparticles replacing the characteristic band of -NH2 at 1629 cm(-1) with the protein characteristic band at 1744 cm(-1) and 1712 cm(-1). Magnetic measurements determined that PON1-bound nanoparticles have also favorable superparamagnetic properties with zero coercivity and remanence though a slightly smaller saturation magnetization due to the decrease of magnetic moment in the volume friction. The kinetic measurements indicated the PON1-bound nanoparticles retained 70% of its original activity and exhibited an improved stability than did the free enzyme. The PON1 enzyme is seen to be quite convenient to bind superparamagnetic nanoparticles as support material.
Journal of Nanoscience and Nanotechnology 11/2010; 10(11):7554-9. · 1.56 Impact Factor
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ABSTRACT: Serum paraoxonase (aryldialkylphosphatase, EC 3.1.8.1., PON1) is an esterase protein synthesised by the liver and released into the serum, where it is associated with HDL lipoproteins. In this study, we have determined the in vitro effects of the following antibiotics: sodium ampicillin, ciprofloxacin, Rifamycin SV and clindamiycin phosphate, on human hepatoma (HepG2) cells (liver hPON1). All the antibiotics caused a dose-dependent and time-dependent decrease in the paraoxonase activity while Rifamycin SV was the most effective antibiotic due to its low 50% inhibition concentration (IC(50)) value. Liver hPON1 activity was determined using paraoxon as a substrate. The IC(50) values of the drugs were calculated from graphs of hydratase activity (%) by plotting concentration of the drugs that showed an inhibition effect.
Journal of Enzyme Inhibition and Medicinal Chemistry 10/2010; 25(5):715-9. · 1.62 Impact Factor
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ABSTRACT: The β-carbonic anhydrase from Saccharomyces cerevisiae (CA, EC 4.2.1.1), scCA, which is encoded by the Nce103 gene, is an effective catalyst for CO2 hydration to bicarbonate and protons, with a kcat of 9.4 x 105 s-1, and kcat/KM of 9.8 x 107 M-1.s-1. Its inhibition with anions and sulfonamides has been investigated, as well as its activation with amines and amino acids. Bromide, iodide and sulfamide, were the best anion inhibitors, with KIs of 8.7 - 10.8 μM. Benzenesulfonamides substituted in 2-, 4- and 3,4-positions with amino, alkyl, halogeno and hydroxyalkyl moieties had KIs in the range of 0.976 - 18.45 μM. Better inhibition (KIs in the range of 154 - 654 nM) was observed for benzenesulfonamides incorporating aminoalkyl/carboxyalkyl moieties or halogenosulfanilamides; benzene- 1,3-disulfonamides; simple heterocyclic sulfonamides and sulfanilyl-sulfonamides. The clinically used sulfonamides/sulfamate (acetazolamide, ethoxzolamide, methazolamide, dorzolamide, topiramate, celecoxib, etc.) generally showed effective scCA inhibitory activity, with KIs in the range of 82.6 - 133 nM. The best inhibitor (KI of 15.1 nM) was 4-(2-amino-pyrimidin-4-yl)-benzenesulfonamide. Ladrenaline and some piperazines incorporating aminoethyl moieties were the most effective scCA activators. These studies may lead to a better understanding of the role of this enzyme in yeasts/fungi, and since the Nce103 gene is also present in many pathogenic organisms (Candida spp., Cryptococcus neoformans, etc) they may be useful to develop antifungal drugs.
Current Pharmaceutical Design 09/2010; 16(29):3327-3336. · 3.87 Impact Factor
