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Sample records for 4-nitrophthalic acids catechol

  1. Dicarboxylic acid anhydride condensation with compounds containing active methylene groups. 4: Some 4-nitrophthalic anhydride condensation reactions

    NASA Technical Reports Server (NTRS)

    Oskaja, V.; Rotberg, J.

    1985-01-01

    By 4-nitrophthalic anhydride condensation with acetoacetate in acetic anhydride and triethylamine solution with subsequent breakdown of the intermediate condensation product, 5-nitroindanedione-1,3 was obtained. A 4-nitrophthalic anhydride with acetic anhydride, according to reaction conditions, may yield two products: in the presence of potassium acetate and at high temperatures 4-(or 5-)-nitro-2-acetylbenzoic acid is formed: in the presence of triethylamine and at room temperature 5-( or 6-)-nitrophthalic acetic acid is isolated. A 4-nitrophthalic anhydride and malonic acid in pyridine solution according to temperature yield either 5-( or 6-)-nitrophthalic acetic acid or 4-(or 5-)-nitro-2-acetylbenzoic acid.

  2. Intramolecular interactions in ortho-methoxyalkylphenylboronic acids and their catechol esters

    NASA Astrophysics Data System (ADS)

    Adamczyk-Woźniak, Agnieszka; Borys, Krzysztof M.; Czerwińska, Karolina; Gierczyk, Błażej; Jakubczyk, Michał; Madura, Izabela D.; Sporzyński, Andrzej; Tomecka, Ewelina

    2013-12-01

    Catechol esters of ortho-methoxyalkylphenylboronic acids have been synthesized and characterized by 17O NMR spectroscopy. The results were compared with the data for the parent acids. The influence of intramolecular and intermolecular hydrogen bonds on the properties of the boronic acids has been discussed. The 17O NMR data for the boronic esters proved that there are no O → B interactions in the investigated compounds. This fact is connected with weak Lewis acidity of the parent acids and their low sugars' receptors activity. Crystal structure of ortho-methoxyphenylboronic acid catechol ester was determined.

  3. Catechol and humic acid sorption onto a range of laboratory-produced black carbons (biochars).

    PubMed

    Kasozi, Gabriel N; Zimmerman, Andrew R; Nkedi-Kizza, Peter; Gao, Bin

    2010-08-15

    Although the major influence of black carbon (BC) on soil and sediment organic contaminant sorption is widely accepted, an understanding of the mechanisms and natural variation in pyrogenic carbon interaction with natural organic matter (NOM) is lacking. The sorption of a phenolic NOM monomer (catechol) and humic acids (HA) onto BC was examined using biochars made from oak, pine, and grass at 250, 400, and 650 degrees C. Catechol sorption equilibrium occurred after 14 d and was described by a diffusion kinetic model, while HA required only 1 d and followed pseudo-second-order kinetics. Catechol sorption capacity increased with increasing biochar combustion temperature, from pine < oak < grass and from coarse < fine particle size. At lower catechol concentrations, sorption affinity (Freundlich constant, K(f)) was directly related to micropore surface area (measured via CO(2) sorptometry) indicating the predominance of specific adsorption. In contrast, HA exhibited an order of magnitude less sorption (0.1% versus 1%, by weight) due to its exclusion from micropores. Greater sorption of both catechol and HA occurred on biochars with nanopores, i.e. biochars made at higher temperatures. These findings suggest that addition of BC to soil, via natural fires or biochar amendments, will sequester abundant native OM through sorption. PMID:20669904

  4. Kinetic study of the oxidation and nitration of catechols in the presence of nitrous acid ionization equilibria.

    PubMed

    Khalafi, Lida; Rafiee, Mohammad

    2010-02-15

    Conversion of catechols to corresponding nitro derivatives in the presence of nitrous acid dissociation is studied using voltammetry and UV-vis spectrophotometry. The results indicate that the quinones derived from oxidation of catechols by nitrous acid participate in Michael addition reaction with nitrite ion in very mild acidic solutions. Rank annihilation factor analysis RAFA is applied to resolve the two-way kinetic spectra data measured from spectroscopic reactions. The rank of the original data matrix is reduced by one by annihilating the information of each component. It is shown that both reactions are drastically depends on pH and nitrous acid or nitrite ion percentage. The rate constants of oxidation and nitration reactions of catechol derivatives are obtained at the pHs around pK(a) of nitrous acid.

  5. Inhibition of DNA methylation by caffeic acid and chlorogenic acid, two common catechol-containing coffee polyphenols.

    PubMed

    Lee, Won Jun; Zhu, Bao Ting

    2006-02-01

    We studied the modulating effects of caffeic acid and chlorogenic acid (two common coffee polyphenols) on the in vitro methylation of synthetic DNA substrates and also on the methylation status of the promoter region of a representative gene in two human cancer cells lines. Under conditions that were suitable for the in vitro enzymatic methylation of DNA and dietary catechols, we found that the presence of caffeic acid or chlorogenic acid inhibited in a concentration-dependent manner the DNA methylation catalyzed by prokaryotic M.SssI DNA methyltransferase (DNMT) and human DNMT1. The IC50 values of caffeic acid and chlorogenic acid were 3.0 and 0.75 microM, respectively, for the inhibition of M.SssI DNMT-mediated DNA methylation, and were 2.3 and 0.9 microM, respectively, for the inhibition of human DNMT1-mediated DNA methylation. The maximal in vitro inhibition of DNA methylation was approximately 80% when the highest concentration (20 microM) of caffeic acid or chlorogenic acid was tested. Kinetic analyses showed that DNA methylation catalyzed by M.SssI DNMT or human DNMT1 followed the Michaelis-Menten curve patterns. The presence of caffeic acid or chlorogenic acid inhibited DNA methylation predominantly through a non-competitive mechanism, and this inhibition was largely due to the increased formation of S-adenosyl-L-homocysteine (SAH, a potent inhibitor of DNA methylation), resulting from the catechol-O-methyltransferase (COMT)-mediated O-methylation of these dietary catechols. Using cultured MCF-7 and MAD-MB-231 human breast cancer cells, we also demonstrated that treatment of these cells with caffeic acid or chlorogenic acid partially inhibited the methylation of the promoter region of the RARbeta gene. The findings of our present study provide a general mechanistic basis for the notion that a variety of dietary catechols can function as inhibitors of DNA methylation through increased formation of SAH during the COMT-mediated O-methylation of these dietary

  6. Synthesis of the catechols of natural and synthetic estrogens by using 2-iodoxybenzoic acid (IBX) as the oxidizing agent.

    PubMed

    Saeed, Muhammad; Zahid, Muhammad; Rogan, Eleanor; Cavalieri, Ercole

    2005-03-01

    A method for the synthesis of 2-hydroxyestrone/estradiol, 4-hydroxyestrone/estradiol, 3'-hydroxydiethylstilbestrol, 3'-hydroxyhexestrol, and 3'-hydroxydienestrol is reported, in which 2-iodoxybenzoic acid (IBX) and the corresponding phenolic estrogen are reacted. Treatment of the natural estrogens, estrone/estradiol, with stoichiometric amounts of IBX in dimethylformamide initially yielded a mixture of estrone/estradiol-2,3- and -3,4-quinones, which were reduced in situ to the corresponding catechols by treatment with a 1 M aqueous solution of ascorbic acid. Chromatographic separation of the reaction products afforded 2- and 4-hydroxyestrone/estradiol in good overall yields (79%). In the case of the synthetic estrogens containing two identical phenolic rings, protection of one ring is a prerequisite for the synthesis of the monocatechol. Thus, diethylstilbestrol and dienestrol were protected at one phenol ring as their methyl ethers. The resulting monophenols were treated with stoichiometric amounts of IBX for 1 h, followed by treatment with 1 M aqueous ascorbic acid to obtain the corresponding catechols in more than 70% yield. Furthermore, the catechol of diethylstilbestrol, protected at one ring, was reduced by catalytic hydrogenation at the C3-C4 double bond to obtain 3'-hydroxyhexestrol in 90% yield. Removal of the protected methoxy groups of the synthetic estrogen catechols was carried out by treatment with a 1 M solution of boron tribromide in dichloromethane. This method is highly efficient for the preparative scale synthesis of catechols of both natural and synthetic estrogens.

  7. Browning inhibition mechanisms by cysteine, ascorbic acid and citric acid, and identifying PPO-catechol-cysteine reaction products.

    PubMed

    Ali, Hussein M; El-Gizawy, Ahmed M; El-Bassiouny, Rawia E I; Saleh, Mahmoud A

    2015-06-01

    The titled compounds were examined as PPO inhibitors and antibrowning agents; their various mechanisms were investigated and discussed. All compounds reduced significantly both the browning process and PPO activity. Browning index gave strong correlation with PPO activity (r(2) = 0.96, n = 19) indicating that the browning process is mainly enzymatic. Ascorbic acid could reduce the formed quinone instantly to the original substrate (catechol) at high concentration (>1.5 %) while at lower concentrations acted as competitive inhibitor (KI = 0.256 ± 0.067 mM). Cysteine, at higher concentrations (≥1.0 %), reacted with the resulted quinone to give a colorless products while at the low concentrations, cysteine worked as competitive inhibitor (KI = 1.113 ± 0.176 mM). Citric acid acted only as PPO non-competitive inhibitor with KI = 2.074 ± 0.363 mM. The products of PPO-catechole-cysteine reaction could be separation and identification by LC-ESI-MS. Results indicated that the product of the enzymatic oxidation of catechol, quinone, undergoes two successive nucleophilic attacks by cysteine thiol group. Cysteine was condensed with the resulted mono and dithiocatechols to form peptide side chains.

  8. Browning inhibition mechanisms by cysteine, ascorbic acid and citric acid, and identifying PPO-catechol-cysteine reaction products.

    PubMed

    Ali, Hussein M; El-Gizawy, Ahmed M; El-Bassiouny, Rawia E I; Saleh, Mahmoud A

    2015-06-01

    The titled compounds were examined as PPO inhibitors and antibrowning agents; their various mechanisms were investigated and discussed. All compounds reduced significantly both the browning process and PPO activity. Browning index gave strong correlation with PPO activity (r(2) = 0.96, n = 19) indicating that the browning process is mainly enzymatic. Ascorbic acid could reduce the formed quinone instantly to the original substrate (catechol) at high concentration (>1.5 %) while at lower concentrations acted as competitive inhibitor (KI = 0.256 ± 0.067 mM). Cysteine, at higher concentrations (≥1.0 %), reacted with the resulted quinone to give a colorless products while at the low concentrations, cysteine worked as competitive inhibitor (KI = 1.113 ± 0.176 mM). Citric acid acted only as PPO non-competitive inhibitor with KI = 2.074 ± 0.363 mM. The products of PPO-catechole-cysteine reaction could be separation and identification by LC-ESI-MS. Results indicated that the product of the enzymatic oxidation of catechol, quinone, undergoes two successive nucleophilic attacks by cysteine thiol group. Cysteine was condensed with the resulted mono and dithiocatechols to form peptide side chains. PMID:26028748

  9. Kinetic study of electrochemically induced michael reactions of o-quinones with Meldrum's acid derivatives. Synthesis of highly oxygenated catechols.

    PubMed

    Nematollahi, D; Shayani-jam, H

    2008-05-01

    Electrochemical oxidation of catechols has been studied in the presence of Meldrum's acid derivatives as nucleophiles in aqueous solution, by means of cyclic voltammetry and controlled-potential coulometry. Catechols in the Michael addition reaction react with Meldrum's acids to form adducts that can undergo electrooxidation. Such products were obtained in good yields as confirmed by controlled potential electrosynthesis. Such products can be generated in aqueous solutions by means of electrosynthesis, using a carbon electrode in an undivided cell. Furthermore, the homogeneous rate constants of the chemical reaction interposed between electron transfers were estimated by comparing the experimental cyclic voltammetric curves with the digitally simulated ones.

  10. Iron binding efficiency of polyphenols: Comparison of effect of ascorbic acid and ethylenediaminetetraacetic acid on catechol and galloyl groups.

    PubMed

    Tamilmani, Poonkodi; Pandey, Mohan Chandra

    2016-04-15

    Dietary polyphenols are markedly studied for their antioxidant activity. They also have a negative impact on nutrition whereby they interfere with iron absorption. Common dietary polyphenols include: catechins, flavonols, flavanols, flavones, anthocyanins, proanthocyanidins and phenolic acids. Ascorbic acid (AA) and Ethylenediaminetetraacetic acid (EDTA) are commonly used to counter act this reaction and increase iron bioavailability. This study was aimed at determining the effect of AA and EDTA on the catechol or galloyl iron binding ability of pure phenolics, coffee and tea. Phenolic concentrations of 40, 80, 610, 240, 320, 400, 520 and 900 μg/ml were tested against six levels of AA and EDTA. These effects were studied in detail using Multivariate Analysis of Variance (MANOVA) with the hypothesis that there would be one or more mean differences between the ratio of enhancer and the different concentrations of samples tested. AA was found to be more efficient than EDTA in a way that lesser quantity is required for completely overcoming negative iron binding effects of polyphenols and similar samples.

  11. DFT and experimental investigation of catecholate derivatives of benzoic acid and pyridine

    NASA Astrophysics Data System (ADS)

    Hatzipanayioti, Despina; Tzeferakos, George; Petropouleas, Panayiotis

    2008-04-01

    DFT calculations, at the B3LYP/TZVP level of theory for pyrocatechuic acid (2,3-dihydroxybenzoic acid, 2,3-DHBA), 2,3-dihydroxy-pyridine 2,3-DHPY and their ionized and oxidized forms, have been performed, in combination with experimental data. 1H, 13C, 2D COSY NMR, IR and electronic spectra were coupled to the theoretical calculations. The geometrical parameters were checked by reported crystallographic data. The neutral form of pyrocatechuic acid is the most stable, regarding its ionized (mono-, di- or tri-anions) and oxidized ([2,3-DHBA-sqH] -, [2,3-DHBA-sq] 2-, [2,3-DHBA-q] -) species. The most stable conformer 2,3-DHBA-H 3 displays the COOH- group co-planar to the catechol ring, hydrogen bonded with OH(2). In the [2,3-DHBA-H 2] - the stable conformer shows the presence of protonated COOH, while OH(2) is ionized. The tri-anion is the form of 2,3-DHBA with the highest energy. Among the protonated semiquinone radical forms [2,3-DHBA-sqH] -, more stable is the OH(3)-oxidized, cited 21.3 kcal/mol lower in energy from the OH(2)-oxidized; in this latter the COO - group lies perpendicular to the benzene ring. The same calculation procedure fitted on the oxygenated [2,3-DHBA-H-O 2] 2- shows a weak π-bonding between O(2) and dioxygen, strongly H-bonded to OH(3), while the C(2)-O bond order increases. The different way of 2,3-DHBA oxidation parallels the different, from 3,4-isomer, degradation products. Our DFT calculations show that the keto/enol tautomeric forms of the neutral 2,3-DHPY-H 2 differ by 5.02 kcal/mol. Both species give, upon ionization, the [2,3-DHPY-H] - with the OH(2) deprotonated. The electronic density distribution of [2,3-DHPY-q] justifies further reactions (degradation or dienic addition) as experimentally observed.

  12. Investigation of acid-base catalysis in the extradiol and intradiol catechol dioxygenase reactions using a broad specificity mutant enzyme and model chemistry.

    PubMed

    Brivio, Michela; Schlosrich, Janne; Ahmad, Mark; Tolond, Caroline; Bugg, Timothy D H

    2009-04-01

    The extradiol and intradiol catechol dioxygenase reaction mechanisms proceed via a common proximal hydroperoxide intermediate, which is processed via different Criegee 1,2-rearrangements. An R215W mutant of extradiol dioxygenase MhpB, able to produce a mixture of extradiol and intradiol cleavage products, was analysed at pH 5.2-8.6, and the yield of extradiol product was found to be highly pH-dependent, whereas the yield of intradiol product was pH-independent. The acid-base chemistry of a biomimetic reaction for extradiol oxidative catechol cleavage was also investigated, using 1,4,7-triazacyclononane, FeCl(2), and pyridine in methanol, in which pyridine is proposed to act as both a general base and (in protonated form) a general acid. Kinetic experiments using a range of meta- and para-substituted pyridines gave a Brønsted plot of log(v) vs. pK(a) showing a bell-shaped plot. Oxidative catechol cleavage by a pyridine-monosubstituted beta-cyclodextrin in the presence of TACN and FeCl(2) in methanol yielded only intradiol cleavage products. It is therefore proposed that bifunctional acid-base catalysis is required for iron (ii)-dependent extradiol catechol cleavage, whereas the rate-determining step for intradiol catechol cleavage does not involve acid-base catalysis.

  13. Peptide mapping and amino acid sequencing of two catechol 1,2-dioxygenases (CD I1 and CD I2) from Acinetobacter lwoffii K24.

    PubMed

    Kim, S I; Ha, K S

    1997-10-31

    The partial amino acid sequences of two catechol 1,2-dioxygenases (CD I1 and CD I2) from Acinetobacter lwoffii K24 have been determined by analysis of peptides after cleavages with endopeptidase Lys-C, endopeptidase Glu-C, trypsin, and chemicals (cyanogen bromide and BNPS-skatole). They include 248 amino acid sequences (4 fragments) of CD I1 and 211 amino acid sequences (5 fragments) of CD I2. Two enzymes have more than 50% sequence homology with type I catechol 1,2-dioxygenases and less than 30% sequence homology with type II catechol 1,2-dioxygenases. Two enzymes have similar hydropathy profiles in the N-terminal region, suggesting that they have similar secondary structures. PMID:9387151

  14. Heterogeneous Oxidation of Catechol.

    PubMed

    Pillar, Elizabeth A; Zhou, Ruixin; Guzman, Marcelo I

    2015-10-15

    Natural and anthropogenic emissions of aromatic hydrocarbons from biomass burning, agro-industrial settings, and fossil fuel combustion contribute precursors to secondary aerosol formation (SOA). How these compounds are processed under humid tropospheric conditions is the focus of current attention to understand their environmental fate. This work shows how catechol thin films, a model for oxygenated aromatic hydrocarbons present in biomass burning and combustion aerosols, undergo heterogeneous oxidation at the air-solid interface under variable relative humidity (RH = 0-90%). The maximum reactive uptake coefficient of O3(g) by catechol γO3 = (7.49 ± 0.35) × 10(-6) occurs for 90% RH. Upon exposure of ca. 104-μm thick catechol films to O3(g) mixing ratios between 230 ppbv and 25 ppmv, three main reaction pathways are observed. (1) The cleavage of the 1,2 carbon-carbon bond at the air-solid interface resulting in the formation of cis,cis-muconic acid via primary ozonide and hydroperoxide intermediates. Further direct ozonolysis of cis,cis-muconic yields glyoxylic, oxalic, crotonic, and maleic acids. (2) A second pathway is evidenced by the presence of Baeyer-Villiger oxidation products including glutaconic 4-hydroxy-2-butenoic and 5-oxo-2-pentenoic acids during electrospray ionization mass spectrometry (MS) and ion chromatography MS analyses. (3) Finally, indirect oxidation by in situ produced hydroxyl radical (HO(•)) results in the generation of semiquinone radical intermediates toward the synthesis of polyhydoxylated aromatic rings such as tri-, tetra-, and penta-hydroxybenzene. Remarkably, heavier polyhydroxylated biphenyl and terphenyl products present in the extracted oxidized films result from coupling reactions of semiquinones of catechol and its polyhydroxylated rings. The direct ozonolysis of 1,2,3- and 1,2,4-trihydroxybenezene yields 2- and 3-hydroxy-cis,cis-muconic acid, respectively. The production of 2,4- or 3,4-dihdroxyhex-2-enedioic acid is

  15. A selective de-O-methylation of guaiacyl lignans to corresponding catechol derivatives by 2-iodoxybenzoic acid (IBX). The role of the catechol moiety on the toxicity of lignans.

    PubMed

    Bernini, Roberta; Barontini, Maurizio; Mosesso, Pasquale; Pepe, Gaetano; Willför, Stefan M; Sjöholm, Rainer E; Eklund, Patrik C; Saladino, Raffaele

    2009-06-01

    We report here the first selective de-O-methylation of a large panel of guaiacyl lignans to the corresponding catechol derivatives by using IBX as primary oxidant under green conditions (dimethyl carbonate-H(2)O solvent) through an in situ reduction procedure. The influence of the catechol moiety on the cytotoxicity and genotoxicity of new lignan derivatives has been investigated. The results obtained indicated that the presence of the catechol moiety sharply enhances the clastogenic potential (e.g. induction of chromosomal aberrations), the cytotoxicity and the modulation of cell cycle progression with respect to the parent compounds. Thus, despite the in vitro antioxidant activity usually described for catechol derivatives, our results show for the first time the generation of a clastogenic potential, highly indicative of a long-term genetic and cancer risk.

  16. PEM Anchorage on Titanium Using Catechol Grafting

    PubMed Central

    Marie, Hélène; Barrere, Amélie; Schoentstein, Frédérique; Chavanne, Marie-Hélène; Grosgogeat, Brigitte; Mora, Laurence

    2012-01-01

    Background This study deals with the anchorage of polyelectrolyte films onto titanium surfaces via a cathecol-based linker for biomedical applications. Methodology The following study uses a molecule functionalized with a catechol and a carboxylic acid: 3-(3,4-dihydroxyphenyl)propanoic acid. This molecule is anchored to the TiO2 substrate via the catechol while the carboxylic acid reacts with polymers bearing amine groups. By providing a film anchorage of chemisorption type, it makes possible to deposit polyelectrolytes on the surface of titanium. Principal Findings Infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), contact angle and atomic force microscopy (AFM) measurements show that the different steps of grafting have been successfully performed. Conclusions This method based on catechol anchorage of polyelectrolytes open a window towards large possibilities of clinical applications. PMID:23226262

  17. The role of the catecholic and the electrophilic moieties of caffeic acid in Nrf2/Keap1 pathway activation in ovarian carcinoma cell lines.

    PubMed

    Sirota, R; Gibson, D; Kohen, R

    2015-01-01

    In recent years, numerous studies have demonstrated the health benefits of polyphenols. A major portion of polyphenols in western diet are derived from coffee, which is one of the most consumed beverages in the world. It has been shown that many polyphenols gain their beneficial properties (e.g. cancer prevention) through the activation of the Nrf2/Keap1 pathway as well as their direct antioxidant activity. However, activation of Nrf2 in cancer cells might lead to resistance towards therapy through induction of phase II enzymes. In the present work we hypothesize that caffeic acid (CA), a coffee polyphenol, might act as an electrophile in addition to its nucleophilic properties and is capable of inducing the Nrf2/EpRE pathway in cancer cells. The results indicate that CA induces Nrf2 translocation into the nucleus and consequently its transcription. It has been demonstrated that generated hydrogen peroxide is involved in the induction process. It has also been found that this process is induced predominantly via the double bond in CA (Michael acceptor). However, surprisingly the presence of both nucleophilic and electrophilic moieties in CA resulted in a synergetic activation of Nrf2 and phase II enzymes. We also found that CA possesses a dual activity, although inducing GSTP1 and GSR, it inhibiting their enzymatic activity. In conclusion, the mechanism of induction of Nrf2 pathway and phase II enzymes by CA has been elucidated. The electrophilic moiety in CA is essential for the oxidation of the Keap1 protein. It should be noted that while the nucleophilic moiety (the catechol/quinone moiety) can provide scavenging ability, it cannot contribute directly to Nrf2 induction. It was found that this process may be induced by H2O2 produced by the catechol group. On the whole, it appears that CA might play a major role in the cancer cells by enhancing their resistance to treatment.

  18. "Inherently chiral" thiophene-based electrodes at work: a screening of enantioselection ability toward a series of pharmaceutically relevant phenolic or catecholic amino acids, amino esters, and amine.

    PubMed

    Arnaboldi, Serena; Benincori, Tiziana; Cirilli, Roberto; Grecchi, Sara; Santagostini, Laura; Sannicolò, Francesco; Mussini, Patrizia R

    2016-10-01

    "Inherently chiral" thiophene-based electroactive oligomer films have recently been shown to exhibit outstanding chirality manifestations. One of the most exciting among them is an unprecedented enantioselection ability as electrode surfaces. In fact, in preliminary chiral voltammetry experiments, the new electrodes have been shown to both discriminate the enantiomers of chiral probes (either enantiopure or in a mixture, in terms of large differences in peak potentials) and quantify them (in terms of linear dynamic ranges in peak currents), without the need for preliminary separation steps. Such ability has now been tested on a series of chiral DOPA-related molecules, from phenolic amino acid tyrosine (together with its methyl ester) to catecholic amino acid DOPA (together with its methyl ester), to catecholamine epinephrine (adrenaline). The wide-range enantioselectivity of the new inherently chiral electrode surfaces is fully confirmed, as large peak potential differences are obtained for probe enantiomers of the whole series working in common aqueous buffers. Moreover, interesting modulating effects on enantiodiscrimination can be observed as a function of both molecular structure and pH. Graphical abstract Inherently chiral thiophene-based electrodes at work with pharmaceutically relevant probes. PMID:27655334

  19. Spectroscopic investigations of humic-like acids formed via polycondensation reactions between glycine, catechol and glucose in the presence of natural zeolites

    NASA Astrophysics Data System (ADS)

    Fukuchi, Shigeki; Miura, Akitaka; Okabe, Ryo; Fukushima, Masami; Sasaki, Masahide; Sato, Tsutomu

    2010-10-01

    Polycondensation reactions between low-molecular-weight compounds, such as amino acids, sugars and phenols, are crucially important processes in the formation of humic substances, and clay minerals have the ability to catalyze these reactions. In the present study, catechol (CT), glycine (Gly) and glucose (Gl) were used as representative phenols, amino acids and sugars, respectively, and the effects of the catalytic activities of natural zeolites on polycondensation reactions between these compounds were investigated. The extent of polycondensation was evaluated by measuring the specific absorbance at 600 nm ( E600) as an index of the degree of darkening. After a 3-week incubation period, the E600 values for solutions that contained zeolite samples were 4-10 times greater than those measured in the absence of zeolite, suggesting that the zeolite had, in fact, catalyzed the polycondensation reaction. The humic-like acids (HLAs) produced in the reactions were isolated, and their elemental composition and molecular weights determined. When formed in the presence of a zeolite, the nitrogen contents and molecular weights for the HLAs were significantly higher, compared to the HLA sample formed in the absence of zeolite. In addition, solid-state CP-MAS 13C NMR spectra and carboxylic group analyses of the HLA samples indicated that the concentration of carbonyl carbon species for quinones and ketones produced in the presence of zeolite were higher than the corresponding values for samples produced in the absence of a zeolite. Carbonyl carbons in quinones and ketones indicate the nucleophilic characteristics of the samples. Therefore, a nitrogen atom in Gly, which serves as nucleophile, is incorporated into quinones and ketones in CT and Gl. The differences in the catalytic activities of the zeolite samples can be attributed to differences in their transition metal content (Fe, Mn and Ti), which function as Lewis acids.

  20. Engineering catechol 1, 2-dioxygenase by design for improving the performance of the cis, cis-muconic acid synthetic pathway in Escherichia coli.

    PubMed

    Han, Li; Liu, Pi; Sun, Jixue; Wu, Yuanqing; Zhang, Yuanyuan; Chen, Wujiu; Lin, Jianping; Wang, Qinhong; Ma, Yanhe

    2015-01-01

    Regulating and ameliorating enzyme expression and activity greatly affects the performance of a given synthetic pathway. In this study, a new synthetic pathway for cis, cis-muconic acid (ccMA) production was reconstructed without exogenous induction by regulating the constitutive expression of the important enzyme catechol 1,2-dioxygenase (CatA). Next, new CatAs with significantly improved activities were developed to enhance ccMA production using structure-assisted protein design. Nine mutations were designed, simulated and constructed based on the analysis of the CatA crystal structure. These results showed that mutations at Gly72, Leu73 and/or Pro76 in CatA could improve enzyme activity, and the activity of the most effective mutant was 10-fold greater than that of the wild-type CatA from Acinetobacter sp. ADP1. The most productive synthetic pathway with a mutated CatA increased the titer of ccMA by more than 25%. Molecular dynamic simulation results showed that enlarging the entrance of the substrate-binding pocket in the mutants contributed to their increased enzyme activities and thus improved the performance of the synthetic pathway. PMID:26306712

  1. Engineering catechol 1, 2-dioxygenase by design for improving the performance of the cis, cis-muconic acid synthetic pathway in Escherichia coli

    PubMed Central

    Han, Li; Liu, Pi; Sun, Jixue; Wu, Yuanqing; Zhang, Yuanyuan; Chen, Wujiu; Lin, Jianping; Wang, Qinhong; Ma, Yanhe

    2015-01-01

    Regulating and ameliorating enzyme expression and activity greatly affects the performance of a given synthetic pathway. In this study, a new synthetic pathway for cis, cis-muconic acid (ccMA) production was reconstructed without exogenous induction by regulating the constitutive expression of the important enzyme catechol 1,2-dioxygenase (CatA). Next, new CatAs with significantly improved activities were developed to enhance ccMA production using structure-assisted protein design. Nine mutations were designed, simulated and constructed based on the analysis of the CatA crystal structure. These results showed that mutations at Gly72, Leu73 and/or Pro76 in CatA could improve enzyme activity, and the activity of the most effective mutant was 10-fold greater than that of the wild-type CatA from Acinetobacter sp. ADP1. The most productive synthetic pathway with a mutated CatA increased the titer of ccMA by more than 25%. Molecular dynamic simulation results showed that enlarging the entrance of the substrate-binding pocket in the mutants contributed to their increased enzyme activities and thus improved the performance of the synthetic pathway. PMID:26306712

  2. CuII ions and the stilbene-chroman hybrid with a catechol moiety synergistically induced DNA damage, and cell cycle arrest and apoptosis of HepG2 cells: an interesting acid/base-promoted prooxidant reaction.

    PubMed

    Liu, Guo-Yun; Yang, Jie; Dai, Fang; Yan, Wen-Jing; Wang, Qi; Li, Xiu-Zhuang; Ding, De-Jun; Cao, Xiao-Yan; Zhou, Bo

    2012-08-27

    Development of potential cancer treatment strategies by using an exogenous reactive oxygen species (ROS)-generating agent (prooxidant) or redox intervention, has attracted much interest. One effective ROS generation method is to construct a prooxidant system by polyphenolic compounds and Cu(II) ions. This work demonstrates that Cu(II) and the stilbene-chroman hybrid with a catechol moiety could synergistically induce pBR322 plasmid DNA damage, as well as cell cycle arrest and apoptosis of HepG2 cells. Additionally, an interesting acid/base-promoted prooxidant reaction was found. The detailed chemical mechanisms for the reaction of the hybrid with Cu(II) in acid, neutral and base solutions are proposed based on UV/Vis spectral changes and identification of the related oxidative intermediates and products.

  3. Chemical properties of catechols and their molecular modes of toxic action in cells, from microorganisms to mammals.

    PubMed

    Schweigert, N; Zehnder, A J; Eggen, R I

    2001-02-01

    Catechols can undergo a variety of chemical reactions. In this review, we particularly focus on complex formations and the redox chemistry of catechols, which play an inportant role in the toxicity of catechols. In the presence of heavy metals, such as iron or copper, stable complexes can be formed. In the presence of oxidizing agents, catechols can be oxidized to semiquinone radicals and in a next step to o-benzoquinones. Heavy metals may catalyse redox reactions in which catechols are involved. Further chemical properties like the acidity constant and the lipophilicity of different catechols are shortly described as well. As a consequence of the chemical properties and the chemical reactions of catechols, many different reactions can occur with biomolecules such as DNA, proteins and membranes, ultimately leading to non-repairable damage. Reactions with nucleic acids such as adduct formation and strand breaks are discussed among others. Interactions with proteins causing protein and enzyme inactivation are described. The membrane-catechol interactions discussed here are lipid peroxidation and uncoupling. The deleterious effect of the interactions between catechols and the different biomolecules is discussed in the context of the observed toxicities, caused by catechols.

  4. Ion-solvent and ion-ion interactions of phosphomolybdic acid in aqueous solution of catechol at 298.15, 308.15, and 318.15 K

    NASA Astrophysics Data System (ADS)

    Roy, M. N.; Sah, R. S.; Pradhan, P. P.; Roy, P. K.

    2009-11-01

    Apparent molar volume ( V Ø) and viscosity B-coefficients were measured for phosphomolybdicacid in aqueous solution of catechol from solution density ( ρ) and viscosity ( η) at 298.15, 308.15, and 318.15 K at various solute concentrations. The experimental density data were evaluated by Masson equation and the derived data were interpreted in terms of ion-solvent and ion-ion interactions. The viscosity data have been analyzed using Jones-Dole equation and the derived parameters, B and A, have been interpreted in terms of ion-solvent and ion-ion interactions respectively. The structure-making or breaking capacity of the solute under investigation has been discussed in terms of sign of ( δ 2 V {Ø/o}/ δT 2) P . The activation parameters of viscous flow were determined and discussed by application of transition state theory.

  5. Six hydrogen-bonded supramolecular frameworks assembled from organic acids and p-dimethylaminobenzaldehyde

    NASA Astrophysics Data System (ADS)

    Jin, Shouwen; Wang, Lanqing; Lou, Yulei; Liu, Li; Li, Bin; Li, Linyu; Feng, Chao; Liu, Hui; Wang, Daqi

    2016-03-01

    Cocrystallization of the commonly available organic compound, p-dimethylaminobenzaldehyde, with a series of organic acids gave a total of six molecular adducts with the compositions: p-dimethylaminobenzaldehyde : (3,5-dinitrosalicylic acid) [(L) · (Hdsa), Hdsa = 3,5-dinitrosalicylic acid] (1), p-dimethylaminobenzaldehyde : (3-nitrophthalic acid) [(L) · (3-H2npa), 3-H2npa = 3-nitrophthalic acid] (2), p-dimethylaminobenzaldehyde : (4-nitrophthalic acid) [(L) · (4-H2npa), 4-H2npa = 4-nitrophthalic acid] (3), p-dimethylaminobenzaldehyde : (1,5-naphthalenedisulfonic acid) : (NH3)2 [NH4 · (HL) · (nds2-) · NH3, nds- = 1,5-naphthalenedisulfonate] (4), p-dimethylaminobenzaldehyde : (oxalic acid)0.5 [(L) · (H2oa)0.5, H2oa = oxalic acid] (5), and p-dimethylaminobenzaldehyde : (fumaric acid)0.5 [(L) · (H2fum)0.5, H2fum = fumaric acid] (6). The six molecular adducts have been characterized by X-ray diffraction technique, IR, and elemental analysis, and the melting points of all adducts were also reported. And their structural and supramolecular aspects are fully analyzed. Of the six adducts, only 4 is an organic salt and the other five are cocrystals. The crystal packing is interpreted in terms of the strong classical hydrogen bonds as well as other weak non-classical hydrogen bonds. The different families of non-covalent bonds contribute to the stabilization and expansion of the total high-dimensional (2D-3D) frameworks.

  6. Nanofluidic redox cycling amplification for the selective detection of catechol.

    PubMed

    Wolfrum, Bernhard; Zevenbergen, Marcel; Lemay, Serge

    2008-02-15

    We have developed a chip-based nanofluidic device to amplify the electrochemical signal of catechols by orders of magnitude. The amplification is based on rapid redox cycling between plane parallel electrodes inside a nanochannel. We show that it is possible to monitor the signal of only a few hundred molecules residing in the active area of the nanofluidic sensor. Furthermore, due to the nanochannel design, the sensor is immune to interference by molecules undergoing irreversible redox reactions. We demonstrate the selectivity of the device by detecting catechol in the presence of ascorbic acid, whose oxidized form is only stable for a short time. The interference of ascorbic acid is usually a challenge in the detection of catecholamines in biological samples.

  7. Bio-inspired adhesive catechol-conjugated chitosan for biomedical applications: A mini review.

    PubMed

    Ryu, Ji Hyun; Hong, Seonki; Lee, Haeshin

    2015-11-01

    The development of adhesive materials, such as cyanoacrylate derivatives, fibrin glues, and gelatin-based adhesives, has been an emerging topic in biomaterial science because of the many uses of these materials, including in wound healing patches, tissue sealants, and hemostatic materials. However, most bio-adhesives exhibit poor adhesion to tissue and related surfaces due to the presence of body fluid. For a decade, studies have aimed at addressing this issue by developing wet-resistant adhesives. Mussels demonstrate robust wet-resistant adhesion despite the ceaseless waves at seashores, and mussel adhesive proteins play a key role in this adhesion. Adhesive proteins located at the distal end (i.e., those that directly contact surfaces) are composed of nearly 60% of amino acids called 3,4-dihydroxy-l-phenylalanine (DOPA), lysine, and histidine, which contain side chains of catechol, primary amines, and secondary amines, respectively. Inspired by the abundant catecholamine in mussel adhesive proteins, researchers have developed various types of polymeric mimics, such as polyethylenimine-catechol, chitosan-catechol, and other related catecholic polymers. Among them, chitosan-catechol is a promising adhesive polymer for biomedical applications. The conjugation of catechol onto chitosan dramatically increases its solubility from zero to nearly 60mg/mL (i.e., 6% w/v) in pH 7 aqueous solutions. The enhanced solubility maximizes the ability of catecholamine to behave similar to mussel adhesive proteins. Chitosan-catechol is biocompatible and exhibits excellent hemostatic ability and tissue adhesion, and thus, chitosan-catechol will be widely used in a variety of medical settings in the future. This review focuses on the various aspects of chitosan-catechol, including its (1) preparation methods, (2) physicochemical properties, and (3) current applications.

  8. Bio-inspired adhesive catechol-conjugated chitosan for biomedical applications: A mini review.

    PubMed

    Ryu, Ji Hyun; Hong, Seonki; Lee, Haeshin

    2015-11-01

    The development of adhesive materials, such as cyanoacrylate derivatives, fibrin glues, and gelatin-based adhesives, has been an emerging topic in biomaterial science because of the many uses of these materials, including in wound healing patches, tissue sealants, and hemostatic materials. However, most bio-adhesives exhibit poor adhesion to tissue and related surfaces due to the presence of body fluid. For a decade, studies have aimed at addressing this issue by developing wet-resistant adhesives. Mussels demonstrate robust wet-resistant adhesion despite the ceaseless waves at seashores, and mussel adhesive proteins play a key role in this adhesion. Adhesive proteins located at the distal end (i.e., those that directly contact surfaces) are composed of nearly 60% of amino acids called 3,4-dihydroxy-l-phenylalanine (DOPA), lysine, and histidine, which contain side chains of catechol, primary amines, and secondary amines, respectively. Inspired by the abundant catecholamine in mussel adhesive proteins, researchers have developed various types of polymeric mimics, such as polyethylenimine-catechol, chitosan-catechol, and other related catecholic polymers. Among them, chitosan-catechol is a promising adhesive polymer for biomedical applications. The conjugation of catechol onto chitosan dramatically increases its solubility from zero to nearly 60mg/mL (i.e., 6% w/v) in pH 7 aqueous solutions. The enhanced solubility maximizes the ability of catecholamine to behave similar to mussel adhesive proteins. Chitosan-catechol is biocompatible and exhibits excellent hemostatic ability and tissue adhesion, and thus, chitosan-catechol will be widely used in a variety of medical settings in the future. This review focuses on the various aspects of chitosan-catechol, including its (1) preparation methods, (2) physicochemical properties, and (3) current applications. PMID:26318801

  9. Spectroscopic Studies of the Catechol Dioxygenases.

    ERIC Educational Resources Information Center

    Que, Lawrence Jr.

    1985-01-01

    The catechol dioxygenases are bacterial iron-containing enzymes that catalyze the oxidative cleavage of catechols. These enzymes serve as a component of nature's mechanisms for degrading aromatic compounds in the environment. The structure and mechanistic aspects of these enzymes are described. (JN)

  10. Heterogeneous reactions of surface-adsorbed catechol with nitrogen dioxide: substrate effects for tropospheric aerosol surrogates.

    PubMed

    Woodill, Laurie A; Hinrichs, Ryan Z

    2010-09-28

    Surface-adsorbed organics can alter the chemistry of tropospheric aerosols thereby impacting photochemical cycles and altering aerosol properties. The nature of the surface can also influence the chemistry of the surface-adsorbed organic. We employed diffuse reflectance infrared spectroscopy (DRIFTS) to monitor the adsorption of gaseous catechol on several tropospheric aerosol surrogates and to investigate the subsequent reactivity of adsorbed catechol with nitrogen dioxide. The dark heterogeneous reaction of NO(2) with NaCl-adsorbed catechol produced 4-nitrocatechol, 1,2-benzoquinone, and the ring-cleaved product muconic acid, with product yields of 88%, 8%, and 4% at relative humidity (RH) < 2%, respectively. The reaction was first-order with respect to both catechol and NO(2). The reactive uptake coefficient for NO(2) + NaCl-adsorbed catechol increased from 3 x 10(-6) at <2% RH to 7 x 10(-6) at 30% RH. These reactions were more than two orders of magnitude more reactive than NaCl without adsorbed catechol. The 4-nitrocatechol product yield was enhanced on NaF, while NaBr-adsorbed catechol produced considerably more 1,2-benzoquinone and muconic acid. This substrate effect is discussed in terms of each substrate's ability to polarize the phenol group and hinder hydrogen atom abstraction from intermediate o-semiquinone radicals. These dark heterogeneous reactions may alter the UV-visible absorbing properties of tropospheric aerosols and may also contribute as a dark source of NO(2)(-)/HONO. These results contrast prior observations which found pure catechol thin films unreactive with NO(2), highlighting the need to specifically consider substrate and matrix effects in laboratory systems.

  11. Inhibition of human catechol-O-methyltransferase (COMT)-mediated O-methylation of catechol estrogens by major polyphenolic components present in coffee.

    PubMed

    Zhu, Bao Ting; Wang, Pan; Nagai, Mime; Wen, Yujing; Bai, Hyoung-Woo

    2009-01-01

    In the present study, we investigated the inhibitory effect of three catechol-containing coffee polyphenols, chlorogenic acid, caffeic acid and caffeic acid phenethyl ester (CAPE), on the O-methylation of 2- and 4-hydroxyestradiol (2-OH-E(2) and 4-OH-E(2), respectively) catalyzed by the cytosolic catechol-O-methyltransferase (COMT) isolated from human liver and placenta. When human liver COMT was used as the enzyme, chlorogenic acid and caffeic acid each inhibited the O-methylation of 2-OH-E(2) in a concentration-dependent manner, with IC(50) values of 1.3-1.4 and 6.3-12.5 microM, respectively, and they also inhibited the O-methylation of 4-OH-E(2), with IC(50) values of 0.7-0.8 and 1.3-3.1 microM, respectively. Similar inhibition pattern was seen with human placental COMT preparation. CAPE had a comparable effect as caffeic acid for inhibiting the O-methylation of 2-OH-E(2), but it exerted a weaker inhibition of the O-methylation of 4-OH-E(2). Enzyme kinetic analyses showed that chlorogenic acid and caffeic acid inhibited the human liver and placental COMT-mediated O-methylation of catechol estrogens with a mixed mechanism of inhibition (competitive plus noncompetitive). Computational molecular modeling analysis showed that chlorogenic acid and caffeic acid can bind to human soluble COMT at the active site in a similar manner as the catechol estrogen substrates. Moreover, the binding energy values of these two coffee polyphenols are lower than that of catechol estrogens, which means that coffee polyphenols have higher binding affinity for the enzyme than the natural substrates. This computational finding agreed perfectly with our biochemical data.

  12. Catechol-O-methyltransferase Val158Met genotype and the clinical responses to duloxetine treatment or plasma levels of 3-methoxy-4-hydroxyphenylglycol and homovanillic acid in Japanese patients with major depressive disorder

    PubMed Central

    Atake, Kiyokazu; Yoshimura, Reiji; Hori, Hikaru; Katsuki, Asuka; Nakamura, Jun

    2015-01-01

    Purpose This study investigated the relationships among the plasma levels of catecholamine metabolites, the clinical response to duloxetine treatment, and Val158Met polymorphism of the catechol-O-methyltransferase (COMT) gene. Subjects and methods Sixty-four patients and 30 healthy control subjects were recruited. Major depressive episodes were diagnosed using the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision criteria. The severity of depression was evaluated using the 17-item Hamilton Rating Scale for Depression (HAMD17). Patients whose HAMD17 scores were 15 or greater were enrolled in the study. Blood sampling and clinical evaluation were performed at week 0 and week 8. The levels of plasma catecholamine metabolites were measured using high-performance liquid chromatography with electrochemical detection. Genotyping was performed using direct sequencing. Results Thirty of 45 patients (67%) responded to duloxetine treatment during the 8 weeks of treatment. The baseline plasma levels of 3-methoxy-4-hydroxyphenylglycol (MHPG), but not homovanillic acid (HVA), were lower in patients with major depressive disorder (MDD) who had the Val/Val genotype than in patients who were Met-carriers. Patients with MDD and the Val/Val genotype, but not Met carriers, had increased plasma levels of MHPG after 8 weeks of duloxetine treatment. The baseline plasma MHPG levels in healthy control subjects with the Val/Val genotype were significantly higher than those in patients with MDD. Among the subjects in the MDD group with the Val/Val genotype, the plasma MHPG levels increased to the same degree as in the healthy control subjects with the Val/Val genotype after 8 weeks of duloxetine treatment. Conclusion The relationship among the COMT Val158Met polymorphism, plasma levels of catecholamine metabolites, and responses to duloxetine is complex. Nevertheless, our results suggest that patients with MDD and the

  13. Heterogeneous Reactions of Surface-Adsorbed Catechol: A Comparison of Tropospheric Aerosol Surrogates

    NASA Astrophysics Data System (ADS)

    Hinrichs, R. Z.; Woodill, L. A.

    2009-12-01

    Surface-adsorbed organics can alter the chemistry of tropospheric solid-air interfaces, such as aerosol and ground level surfaces, thereby impacting photochemical cycles and altering aerosol properties. The nature of the surface can also influence the chemistry of the surface-adsorbed organic. We employed diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) to monitor the adsorption of gaseous catechol on several tropospheric aerosol surrogates and to investigate the subsequent reactivity of adsorbed-catechol with nitrogen dioxide and, in separate preliminary experiments, ozone. Graphite, kaolinite, and sodium halide (NaF, NaCl, NaBr) powders served as carbonaceous, mineral and sea salt aerosol surrogates, respectively. Broad OH stretching bands for adsorbed catechol shifted to lower wavenumber with peak frequencies following the trend NaBr > NaCl > NaF ≈ kaolinite, consistent with the increasing basicity of the halide anions and basic Brønsted sites on kaolinite. The dark heterogeneous reaction of NO2 with NaCl-adsorbed catechol at relative humidity (RH) <2% promoted nitration forming 4-nitrocatechol and oxidation forming 1,2-benzoquinone and the ring cleavage product muconic acid, with product yields of 88%, 8%, and 4%, respectively. 4-Nitrocatechol was the dominant product for catechol adsorbed on NaF and kaolinite, while NaBr-adsorbed catechol produced less 4-nitrocatechol and more 1,2-benzoquinone and muconic acid. For all three sodium halides, the reactions of NO2 with adsorbed catechol were orders of magnitude faster than between NO2 and each NaX substrate. 4-Nitrocatechol rates and product yields were consistent with the relative ability of each substrate to enhance the deprotonated nature of adsorbed-catechol. Increasing the relative humidity caused the rate of each product channel to decrease and also altered the product branching ratios. Most notably, 1,2-benzoquinone formation decreased significantly even at 13% RH. The dramatic

  14. Synthesis and structure/antioxidant activity relationship of novel catecholic antioxidant structural analogues to hydroxytyrosol and its lipophilic esters.

    PubMed

    Bernini, Roberta; Crisante, Fernanda; Barontini, Maurizio; Tofani, Daniela; Balducci, Valentina; Gambacorta, Augusto

    2012-08-01

    A large panel of novel catecholic antioxidants and their fatty acid or methyl carbonate esters has been synthesized in satisfactory to good yields through a 2-iodoxybenzoic acid (IBX)-mediated aromatic hydroxylation as the key step. The new catechols are structural analogues of naturally occurring hydroxytyrosol (3,4-DHE). To evaluate structure/activity relationships, the antioxidant properties of all catecholic compounds were evaluated in vitro by ABTS assay and on whole cells by DCF fluorometric assay and compared with that of the corresponding already known hydroxytyrosyl derivatives. Results outline that all of the new catechols show antioxidant capacity in vitro higher than that of the corresponding hydroxytyrosyl derivatives. Less evident positive effects have been detected in whole cells experiments. Cytotoxicity experiments, using MTT assay, on a representative set of compounds evidenced no influence in cell survival.

  15. Transformation of phenol, catechol, guaiacol and syringol exposed to sodium hypochlorite.

    PubMed

    Michałowicz, Jaromir; Duda, Wirgiliusz; Stufka-Olczyk, Jadwiga

    2007-01-01

    Germs, xenobiotics and organic matter that influence the colour, turbidity and organoloeptic properties of water are removed by chlorination. Unfortunately, chlorine oxidants including sodium hypochlorite, used in water treatment induce processes that partly convert the treated compounds to unwanted chlorinated derivatives. The purpose of this work was to analyse the efficiency of transformation of phenol, catechol, guaiacol and syringol exposed to sodium hypochlorite and determine the intermediates formed during oxidative conversion of these compounds. The analysis was performed in aerobic conditions, both in acidic (pH 4.0) and alkaline (pH 8.0) medium. The effectiveness of transformation was slightly higher in acidic in comparison to alkaline conditions. Some chlorophenols, such as 2-chlorophenol, 2,4-dichlorophenol, 2,4,5-trichlorophenol and pentachlorophenol were determined as the products of phenol conversion. Chlorophenols were also formed during catechol, guaiacol and syringol transformation by replacement of hydroxy and methoxy residues by chlorine atoms. Moreover, some chlorocatechols and chlorinated methoxyphenols were determined during catechol and methoxyphenols transformations. Higher concentrations of chlorinated compounds were observed in the alkaline environment during phenol transformation. Conversion of catechol and methoxyphenols generated higher amounts of chlorinated intermediates in the acidic medium. In samples carboxylic acids like acetic and formic acids were determined. The formation of these compounds was the result of the cleavage of aromatic structure of phenols.

  16. Noncovalent-bonded 1D-3D supramolecular architectures from 2-methylquinoline/quinoline with monocarboxylic acid and dicarboxylic acid

    NASA Astrophysics Data System (ADS)

    Gao, Xingjun; Jin, Shouwen; Jin, Li; Ye, XiangHang; Zheng, Lu; Li, JingWen; Jin, BinPeng; Wang, Daqi

    2014-10-01

    Studies concentrating on noncovalent weak interactions between the organic base of 2-methylquinoline/quinoline, and carboxylic acid derivatives have led to an increased understanding of the role 2-methylquinoline/quinoline have in binding with carboxylic acids. Here anhydrous multicomponent organic acid-base adducts of 2-methylquinoline/quinoline have been prepared with carboxylic acids that ranged from monocarboxylic acid to dicarboxylic acid such as p-nitrobenzoic acid, (4-chloro-phenoxy)-acetic acid, 4-hydroxy-benzoic acid, 5-bromosalicylic acid, 2,4-dihydroxybenzoic acid, α-ketoglutaric acid, and 4-nitrophthalic acid. The seven crystalline complexes were characterized by X-ray diffraction analysis, IR, m.p., and elemental analysis. These structures adopted the hetero supramolecular synthons. Analysis of the crystal packing of 1-7 suggests that there are Nsbnd H⋯O, Osbnd H⋯N, and Osbnd H⋯O hydrogen bonds (charge assisted or neutral) between the acid and quinoline moieties in the studied compounds. Except the classical hydrogen bonding interactions, the secondary propagating interactions also play important roles in structure extension. These weak interactions combined, these compounds displayed 1D-3D framework structure.

  17. Regioselectivity of catechol O-methyltransferase confers enhancement of catalytic activity

    NASA Astrophysics Data System (ADS)

    Tsao, Douglas; Liu, Shubin; Dokholyan, Nikolay V.

    2011-04-01

    Catechol O-methyltransferase (COMT) metabolizes catechol moieties by methylating a single hydroxyl group at the meta- or para- hydroxyl position. Hydrophobic amino acids near the active site of COMT influence the regioselectivity of this reaction. Our sequence analysis highlights their importance by showing that these residues are highly conserved throughout evolution. Reaction barriers calculated in the gas phase reveal a lower barrier during methylation at the meta- position, suggesting that the observed meta-regioselectivity of COMT can be attributed to the substrate itself, and that COMT has evolved residues to orient the substrate in a manner that increases the rate of catalysis.

  18. Multimodal underwater adsorption of oxide nanoparticles on catechol-based polymer nanosheets

    NASA Astrophysics Data System (ADS)

    Yamamoto, Shunsuke; Uchiyama, Shun; Miyashita, Tokuji; Mitsuishi, Masaya

    2016-03-01

    Multimodal underwater adsorption behaviour of catechol units was demonstrated by examining the adsorption of different oxide nanoparticles on nanoscale-integrated polymer nanosheets. Catechol-based polymer nanosheets were fabricated using the Langmuir-Blodgett (LB) technique with random copolymers (p(DDA/DMA)s) of N-dodecylacrylamide (DDA) and dopamine methacrylamide (DMA). The p(DDA/DMA) nanosheets were immersed into water dispersions of SiO2, Al2O3, and WO3 nanoparticles (NPs) respectively. The results show that the adsorption properties can be altered by varying the NP type: SiO2 NP adsorption was observed only below pH = 6, at which the o-quinone form in p(DDA/DMA) nanosheets transforms into the catechol form or vice versa. However, their transition point for Al2O3 NP adsorption was found at approximately pH 10, at which the surface potential of Al2O3 NPs changes the charge polarity, indicating that the electrostatic interaction is predominant. For WO3 NPs, adsorption was observed when citric acid, which modifies the surface of WO3 NPs by complex formation, was used as a pH-controlling agent, but no adsorption was found for hydrochloric acid used as a pH controlling agent. FT-IR measurements proved that miniscule amounts of water molecules were trapped in p(DDA/DMA) nanosheets and that they acquired hydrogen bonding network formations, which might assist nanoparticle adsorption underwater and make the catechol units adjustable. The results indicate that the nanoscale spatial arrangements of catechol units in films are crucially important for the application of multimodal adsorption of oxide nanoparticles on catechol-based polymer materials.Multimodal underwater adsorption behaviour of catechol units was demonstrated by examining the adsorption of different oxide nanoparticles on nanoscale-integrated polymer nanosheets. Catechol-based polymer nanosheets were fabricated using the Langmuir-Blodgett (LB) technique with random copolymers (p(DDA/DMA)s) of N

  19. pH-dependent cross-linking of catechols through oxidation via Fe(3+) and potential implications for mussel adhesion.

    PubMed

    Fullenkamp, Dominic E; Barrett, Devin G; Miller, Dusty R; Kurutz, Josh W; Messersmith, Phillip B

    2014-01-01

    The mussel byssus is a remarkable attachment structure that is formed by injection molding and rapid in-situ hardening of concentrated solutions of proteins enriched in the catecholic amino acid 3,4-dihydroxy-L-phenylalanine (DOPA). Fe(3+), found in high concentrations in the byssus, has been speculated to participate in redox reactions with DOPA that lead to protein polymerization, however direct evidence to support this hypothesis has been lacking. Using small molecule catechols, DOPA-containing peptides, and native mussel foot proteins, we report the first direct observation of catechol oxidation and polymerization accompanied by reduction of Fe(3+) to Fe(2+). In the case of the small molecule catechol, we identified two dominant dimer species and characterized their connectivities by nuclear magnetic resonance (NMR), with the C6-C6 and C5-C6 linked species as the major and minor products, respectively. For the DOPA-containing peptide, we studied the pH dependence of the reaction and demonstrated that catechol polymerization occurs readily at low pH, but is increasingly diminished in favor of metal-catechol coordination interactions at higher pH. Finally, we demonstrate that Fe(3+) can induce cross-links in native byssal mussel proteins mefp-1 and mcfp-1 at acidic pH. Based on these findings, we discuss the potential implications to the chemistry of mussel adhesion.

  20. pH-dependent cross-linking of catechols through oxidation via Fe(3+) and potential implications for mussel adhesion.

    PubMed

    Fullenkamp, Dominic E; Barrett, Devin G; Miller, Dusty R; Kurutz, Josh W; Messersmith, Phillip B

    2014-01-01

    The mussel byssus is a remarkable attachment structure that is formed by injection molding and rapid in-situ hardening of concentrated solutions of proteins enriched in the catecholic amino acid 3,4-dihydroxy-L-phenylalanine (DOPA). Fe(3+), found in high concentrations in the byssus, has been speculated to participate in redox reactions with DOPA that lead to protein polymerization, however direct evidence to support this hypothesis has been lacking. Using small molecule catechols, DOPA-containing peptides, and native mussel foot proteins, we report the first direct observation of catechol oxidation and polymerization accompanied by reduction of Fe(3+) to Fe(2+). In the case of the small molecule catechol, we identified two dominant dimer species and characterized their connectivities by nuclear magnetic resonance (NMR), with the C6-C6 and C5-C6 linked species as the major and minor products, respectively. For the DOPA-containing peptide, we studied the pH dependence of the reaction and demonstrated that catechol polymerization occurs readily at low pH, but is increasingly diminished in favor of metal-catechol coordination interactions at higher pH. Finally, we demonstrate that Fe(3+) can induce cross-links in native byssal mussel proteins mefp-1 and mcfp-1 at acidic pH. Based on these findings, we discuss the potential implications to the chemistry of mussel adhesion. PMID:25243062

  1. The role of catechol-O-methyltransferase in catechol-enhanced erythroid differentiation of K562 cells

    SciTech Connect

    Suriguga,; Li, Xiao-Fei; Li, Yang; Yu, Chun-Hong; Li, Yi-Ran; Yi, Zong-Chun

    2013-12-15

    Catechol is widely used in pharmaceutical and chemical industries. Catechol is also one of phenolic metabolites of benzene in vivo. Our previous study showed that catechol improved erythroid differentiation potency of K562 cells, which was associated with decreased DNA methylation in erythroid specific genes. Catechol is a substrate for the catechol-O-methyltransferase (COMT)-mediated methylation. In the present study, the role of COMT in catechol-enhanced erythroid differentiation of K562 cells was investigated. Benzidine staining showed that exposure to catechol enhanced hemin-induced hemoglobin accumulation and induced mRNA expression of erythroid specific genes in K562 cells. Treatment with catechol caused a time- and concentration-dependent increase in guaiacol concentration in the medium of cultured K562 cells. When COMT expression was knocked down by COMT shRNA expression in K562 cells, the production of guaiacol significantly reduced, and the sensitivity of K562 cells to cytotoxicity of catechol significantly increased. Knockdown of COMT expression by COMT shRNA expression also eliminated catechol-enhanced erythroid differentiation of K562 cells. In addition, the pre-treatment with methyl donor S-adenosyl-L-methionine or its demethylated product S-adenosyl-L-homocysteine induced a significant increase in hemin-induced Hb synthesis in K562 cells and the mRNA expression of erythroid specific genes. These findings indicated that O-methylation catalyzed by COMT acted as detoxication of catechol and involved in catechol-enhanced erythroid differentiation of K562 cells, and the production of S-adenosyl-L-homocysteine partly explained catechol-enhanced erythroid differentiation. - Highlights: • Catechol enhanced hemin-induced hemoglobin accumulation. • COMT-catalyzed methylation acted as detoxication of catechol. • COMT involved in catechol-enhanced erythroid differentiation.

  2. Catechol oxidation by ozone and hydroxyl radicals at the air-water interface.

    PubMed

    Pillar, Elizabeth A; Camm, Robert C; Guzman, Marcelo I

    2014-12-16

    Anthropogenic emissions of aromatic hydrocarbons promptly react with hydroxyl radicals undergoing oxidation to form phenols and polyphenols (e.g., catechol) typically identified in the complex mixture of humic-like substances (HULIS). Because further processing of polyphenols in secondary organic aerosols (SOA) can continue mediated by a mechanism of ozonolysis at interfaces, a better understanding about how these reactions proceed at the air-water interface is needed. This work shows how catechol, a molecular probe of the oxygenated aromatic hydrocarbons present in SOA, can contribute interfacial reactive species that enhance the production of HULIS under atmospheric conditions. Reactive semiquinone radicals are quickly produced upon the encounter of 40 ppbv-6.0 ppmv O3(g) with microdroplets containing [catechol] = 1-150 μM. While the previous pathway results in the instantaneous formation of mono- and polyhydroxylated aromatic rings (PHA) and chromophoric mono- and polyhydroxylated quinones (PHQ), a different channel produces oxo- and dicarboxylic acids of low molecular weight (LMW). The cleavage of catechol occurs at the 1,2 carbon-carbon bond at the air-water interface through the formation of (1) an ozonide intermediate, (2) a hydroperoxide, and (3) cis,cis-muconic acid. However, variable [catechol] and [O3(g)] can affect the ratio of the primary products (cis,cis-muconic acid and trihydroxybenzenes) and higher order products observed (PHA, PHQ, and LMW oxo- and dicarboxylic acids). Secondary processing is confirmed by mass spectrometry, showing the production of crotonic, maleinaldehydic, maleic, glyoxylic, and oxalic acids. The proposed pathway can contribute precursors to aqueous SOA (AqSOA) formation, converting aromatic hydrocarbons into polyfunctional species widely found in tropospheric aerosols with light-absorbing brown carbon.

  3. Catechol oxidation by ozone and hydroxyl radicals at the air-water interface.

    PubMed

    Pillar, Elizabeth A; Camm, Robert C; Guzman, Marcelo I

    2014-12-16

    Anthropogenic emissions of aromatic hydrocarbons promptly react with hydroxyl radicals undergoing oxidation to form phenols and polyphenols (e.g., catechol) typically identified in the complex mixture of humic-like substances (HULIS). Because further processing of polyphenols in secondary organic aerosols (SOA) can continue mediated by a mechanism of ozonolysis at interfaces, a better understanding about how these reactions proceed at the air-water interface is needed. This work shows how catechol, a molecular probe of the oxygenated aromatic hydrocarbons present in SOA, can contribute interfacial reactive species that enhance the production of HULIS under atmospheric conditions. Reactive semiquinone radicals are quickly produced upon the encounter of 40 ppbv-6.0 ppmv O3(g) with microdroplets containing [catechol] = 1-150 μM. While the previous pathway results in the instantaneous formation of mono- and polyhydroxylated aromatic rings (PHA) and chromophoric mono- and polyhydroxylated quinones (PHQ), a different channel produces oxo- and dicarboxylic acids of low molecular weight (LMW). The cleavage of catechol occurs at the 1,2 carbon-carbon bond at the air-water interface through the formation of (1) an ozonide intermediate, (2) a hydroperoxide, and (3) cis,cis-muconic acid. However, variable [catechol] and [O3(g)] can affect the ratio of the primary products (cis,cis-muconic acid and trihydroxybenzenes) and higher order products observed (PHA, PHQ, and LMW oxo- and dicarboxylic acids). Secondary processing is confirmed by mass spectrometry, showing the production of crotonic, maleinaldehydic, maleic, glyoxylic, and oxalic acids. The proposed pathway can contribute precursors to aqueous SOA (AqSOA) formation, converting aromatic hydrocarbons into polyfunctional species widely found in tropospheric aerosols with light-absorbing brown carbon. PMID:25423038

  4. Removal of arsenic, vanadium and/or nickel compounds from spent catecholated polymer

    DOEpatents

    Fish, R.H.

    1987-04-21

    Described is a process for removing arsenic, vanadium, and/or nickel from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. For vanadium and nickel removal an amine, preferably a diamine is included. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic, vanadium, and/or nickel bound to it from contacting petroliferous liquid as described above and involves: treating the spent polymer containing any vanadium and/or nickel with an aqueous acid to achieve an acid pH; and, separating the solids from the liquid; and then treating said spent catecholated polystyrene, at a temperature in the range of about 20 to 100 C with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10; and, separating the solids and liquids from each other. Preferably the regeneration treatment of arsenic containing catecholated polymer is in two steps wherein the first step is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, the steps are repeated using a bicarbonate.

  5. Removal of arsenic, vanadium and/or nickel compounds from spent catecholated polymer

    DOEpatents

    Fish, Richard H.

    1987-01-01

    Described is a process for removing arsenic, vanadium, and/or nickel from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. For vanadium and nickel removal an amine, preferably a diamine is included. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic, vanadium, and/or nickel bound to it from contacting petroliferous liquid as described above and involves: treating the spent polymer containing any vanadium and/or nickel with an aqueous acid to achieve an acid pH; and, separating the solids from the liquid; and then treating said spent catecholated polystyrene, at a temperature in the range of about 20.degree. to 100.degree. C. with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10; and, separating the solids and liquids from each other. Preferably the regeneration treatment of arsenic containing catecholated polymer is in two steps wherein the first step is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, the steps are repeated using a bicarbonate.

  6. Aluminum complexation by catechol as determined by ultraviolet spectrophotometry

    SciTech Connect

    Sikora, F.J.; McBride, M.B.

    1989-03-01

    Methods of ultraviolet (UV) spectrophotometry were used to determine the stoichiometry and association constant for the Al-catechol complex from pH 3.8 to 4.6. Job's method of continuous variation indicated the Al-catechol complex had a 1:1 stoichiometry in the pH range studied. Aluminum titrations of catechol and pH titrations of catechol plus Al resulted in a shift in the UV spectra due to the formation of an Al-catechol complex absorbing UV radiation uniquely different than that of free catechol. General equations were developed for the determination of association constants assuming an organic and Al-organic complex absorb UV radiation. Aluminum titrations with constant catechol concentration yielded a log k/sub 0.1//sup c/ of 16.22 for a 1:1 Al-catechol complex. Calculated absorbance as a function of pH agree dwell with experimental pH titrations of solutions containing catechol plus Al. The fact that Al can be complexed by catechol at low pH indicates the o-hydroxy group provides a potential source for Al complexation in soil and surface waters.

  7. The role of catechol-O-methyltransferase in catechol-enhanced erythroid differentiation of K562 cells.

    PubMed

    Suriguga; Li, Xiao-Fei; Li, Yang; Yu, Chun-Hong; Li, Yi-Ran; Yi, Zong-Chun

    2013-12-15

    Catechol is widely used in pharmaceutical and chemical industries. Catechol is also one of phenolic metabolites of benzene in vivo. Our previous study showed that catechol improved erythroid differentiation potency of K562 cells, which was associated with decreased DNA methylation in erythroid specific genes. Catechol is a substrate for the catechol-O-methyltransferase (COMT)-mediated methylation. In the present study, the role of COMT in catechol-enhanced erythroid differentiation of K562 cells was investigated. Benzidine staining showed that exposure to catechol enhanced hemin-induced hemoglobin accumulation and induced mRNA expression of erythroid specific genes in K562 cells. Treatment with catechol caused a time- and concentration-dependent increase in guaiacol concentration in the medium of cultured K562 cells. When COMT expression was knocked down by COMT shRNA expression in K562 cells, the production of guaiacol significantly reduced, and the sensitivity of K562 cells to cytotoxicity of catechol significantly increased. Knockdown of COMT expression by COMT shRNA expression also eliminated catechol-enhanced erythroid differentiation of K562 cells. In addition, the pre-treatment with methyl donor S-adenosyl-L-methionine or its demethylated product S-adenosyl-L-homocysteine induced a significant increase in hemin-induced Hb synthesis in K562 cells and the mRNA expression of erythroid specific genes. These findings indicated that O-methylation catalyzed by COMT acted as detoxication of catechol and involved in catechol-enhanced erythroid differentiation of K562 cells, and the production of S-adenosyl-L-homocysteine partly explained catechol-enhanced erythroid differentiation.

  8. Isozymes of Ipomoea batatas catechol oxidase differ in catalase-like activity.

    PubMed

    Gerdemann, C; Eicken, C; Magrini, A; Meyer, H E; Rompel, A; Spener, F; Krebs, B

    2001-07-01

    The amino acid sequences of two isozymes of catechol oxidase from sweet potatoes (Ipomoea batatas) were determined by Edman degradation of BrCN cleavage fragments of the native protein and by sequencing of amplified cDNA fragments. Sequence alignment and phylogenetic analysis of plant catechol oxidases revealed about 80% equidistance between the two I. batatas catechol oxidases and approximately 40--60% to catechol oxidases of other plants. When H(2)O(2) was applied as substrate the 39 kDa isozyme, but not the 40 kDa isozyme, showed catalase-like activity. The structure of the 40 kDa isozyme was modeled on the basis of the published crystal structure of the 39 kDa isozyme [T. Klabunde et al., Nat. Struct. Biol. 5 (1998) 1084]. The active site model closely resembled that of the 39 kDa isozyme determined by crystallography, except for a mutation of Thr243 (40 kDa isozyme) to Ile241 (39 kDa isozyme) close to the dimetal center. This residue difference affects the orientation of the Glu238/236 residue, which is thought to be responsible for the catalase-like activity of the 39 kDa isozyme for which a catalytic mechanism is proposed. PMID:11451442

  9. Role of catechol structure in the adsorption and transformation reactions of L-DOPA in soils.

    PubMed

    Furubayashi, Akihiro; Hiradate, Syuntaro; Fujii, Yoshiharu

    2007-02-01

    3-(3',4'-Dihydroxyphenyl)-L-alanine (L-DOPA), which is synthesized in velvet bean (Mucuna pruriens), inhibits plant growth. The concentration of L-DOPA in soil is reduced by adsorption and transformation reactions, which can result in the reduction of its plant-growth-inhibitory activity. To determine which part of the L-DOPA structure is involved in the adsorption and soil transformation reactions, we compared the kinetics of L-DOPA disappearance in a volcanic ash soil with that of L-phenylalanine (3-phenyl-L-alanine) and L-tyrosine (3-(4'-hydroxyphenyl)-L-alanine), compounds that are similar in structure to L-DOPA but do not have a catechol (o-dihydroxybenzene) moiety. L-Phenylalanine and L-tyrosine were not adsorbed and transformed in the soil at equilibrium pH values between 4 and 7. These results suggest that the adsorption and transformation reactions of L-DOPA in the soil involve the catechol moiety and not the amino and carboxylic acid groups, which are common to all three compounds. Like L-DOPA, (+)-catechin, another allelochemical that contains a catechol moiety, underwent adsorption and soil transformation reactions. Thus, we concluded that the concentrations of allelochemicals bearing a catechol moiety in soils will decrease rapidly owing to adsorption and transformation reactions, and this decrease will be faster in soils with a high pH value or high adsorption ability. Owing to this decrease in concentration, allelopathic phenomena may not occur.

  10. Organic impurity profiling of 3,4-methylenedioxymethamphetamine (MDMA) synthesised from catechol.

    PubMed

    Heather, Erin; Shimmon, Ronald; McDonagh, Andrew M

    2015-03-01

    This work examines the organic impurity profile of 3,4-methylenedioxymethamphetamine (MDMA) that has been synthesised from catechol (1,2-dihydroxybenzene), a common chemical reagent available in industrial quantities. The synthesis of MDMA from catechol proceeded via the common MDMA precursor safrole. Methylenation of catechol yielded 1,3-benzodioxole, which was brominated and then reacted with magnesium allyl bromide to form safrole. Eight organic impurities were identified in the synthetic safrole. Safrole was then converted to 3,4-methylenedioxyphenyl-2-propanone (MDP2P) using two synthetic methods: Wacker oxidation (Route 1) and an isomerisation/peracid oxidation/acid dehydration method (Route 2). MDMA was then synthesised by reductive amination of MDP2P. Thirteen organic impurities were identified in MDMA synthesised via Route 1 and eleven organic impurities were identified in MDMA synthesised via Route 2. Overall, organic impurities in MDMA prepared from catechol indicated that synthetic safrole was used in the synthesis. The impurities also indicated which of the two synthetic routes was utilised.

  11. Isozymes of Ipomoea batatas catechol oxidase differ in catalase-like activity.

    PubMed

    Gerdemann, C; Eicken, C; Magrini, A; Meyer, H E; Rompel, A; Spener, F; Krebs, B

    2001-07-01

    The amino acid sequences of two isozymes of catechol oxidase from sweet potatoes (Ipomoea batatas) were determined by Edman degradation of BrCN cleavage fragments of the native protein and by sequencing of amplified cDNA fragments. Sequence alignment and phylogenetic analysis of plant catechol oxidases revealed about 80% equidistance between the two I. batatas catechol oxidases and approximately 40--60% to catechol oxidases of other plants. When H(2)O(2) was applied as substrate the 39 kDa isozyme, but not the 40 kDa isozyme, showed catalase-like activity. The structure of the 40 kDa isozyme was modeled on the basis of the published crystal structure of the 39 kDa isozyme [T. Klabunde et al., Nat. Struct. Biol. 5 (1998) 1084]. The active site model closely resembled that of the 39 kDa isozyme determined by crystallography, except for a mutation of Thr243 (40 kDa isozyme) to Ile241 (39 kDa isozyme) close to the dimetal center. This residue difference affects the orientation of the Glu238/236 residue, which is thought to be responsible for the catalase-like activity of the 39 kDa isozyme for which a catalytic mechanism is proposed.

  12. Revealing the role of catechol moieties in the interactions between peptides and inorganic surfaces.

    PubMed

    Das, Priyadip; Reches, Meital

    2016-08-18

    Catechol (1,2-dihydroxy benzene) moieties are being widely used today in new adhesive technologies. Understanding their mechanism of action is therefore of high importance for developing their applications in materials science. This paper describes a single-molecule study of the interactions between catechol-related amino acid residues and a well-defined titanium dioxide (TiO2) surface. It is the first quantified measurement of the adhesion of these residues with a well-defined TiO2 surface. Single-molecule force spectroscopy measurements with AFM determined the role of different substitutions of the catechol moiety on the aromatic ring in the adhesion to the surface. These results shed light on the nature of interactions between these residues and inorganic metal oxide surfaces. This information is important for the design and fabrication of catechol-based materials such as hydrogels, coatings, and composites. Specifically, the interaction with TiO2 is important for the development of solar cells. PMID:27503417

  13. Glucosylation of Catechol with the GTFA Glucansucrase Enzyme from Lactobacillus reuteri and Sucrose as Donor Substrate.

    PubMed

    te Poele, Evelien M; Grijpstra, Pieter; van Leeuwen, Sander S; Dijkhuizen, Lubbert

    2016-04-20

    Lactic acid bacteria use glucansucrase enzymes for synthesis of gluco-oligosaccharides and polysaccharides (α-glucans) from sucrose. Depending on the glucansucrase enzyme, specific α-glucosidic linkages are introduced. GTFA-ΔN (N-terminally truncated glucosyltransferase A) is a glucansucrase enzyme of Lactobacillus reuteri 121 that synthesizes the reuteran polysaccharide with (α1 → 4) and (α1 → 6) glycosidic linkages. Glucansucrases also catalyze glucosylation of various alternative acceptor substrates. At present it is unclear whether the linkage specificity of these enzymes is the same in oligo/polysaccharide synthesis and in glucosylation of alternative acceptor substrates. Our results show that GTFA-ΔN glucosylates catechol into products with up to at least 5 glucosyl units attached. These catechol glucosides were isolated and structurally characterized using 1D/2D (1)H NMR spectroscopy. They contained 1 to 5 glucose units with different (α1 → 4) and (α1 → 6) glycosidic linkage combinations. Interestingly, a branched catechol glucoside was also formed along with a catechol glucoside with 2 successive (α1 → 6) glycosidic linkages, products that are absent when only sucrose is used as both glycosyl donor and acceptor substrate. PMID:26898769

  14. Synthesis and Evaluation of Heterocyclic Catechol Mimics as Inhibitors of Catechol-O-methyltransferase (COMT)

    PubMed Central

    2015-01-01

    3-Hydroxy-4-pyridinones and 5-hydroxy-4-pyrimidinones were identified as inhibitors of catechol-O-methyltransferase (COMT) in a high-throughput screen. These heterocyclic catechol mimics exhibit potent inhibition of the enzyme and an improved toxicity profile versus the marketed nitrocatechol inhibitors tolcapone and entacapone. Optimization of the series was aided by X-ray cocrystal structures of the novel inhibitors in complex with COMT and cofactors SAM and Mg2+. The crystal structures suggest a mechanism of inhibition for these heterocyclic inhibitors distinct from previously disclosed COMT inhibitors. PMID:25815153

  15. Condensed-phase versus gas-phase ozonolysis of catechol: A combined experimental and theoretical study

    NASA Astrophysics Data System (ADS)

    Barnum, Timothy J.; Medeiros, Nicholas; Hinrichs, Ryan Z.

    2012-08-01

    Anthropogenic emissions of volatile aromatic compounds contribute to the formation of secondary organic aerosols (SOA), especially in urban environments. Aromatic SOA precursors typically require oxidation by hydroxyl radicals, although recent work suggests that ozonolysis of 1,2-benzenediols produces SOA in high yields. We employed attenuated total reflectance and transmission infrared spectroscopy to investigate the heterogeneous ozonolysis of catechol thin films. Formation of the dominant condensed-phase product muconic acid was highly dependent on relative humidity (RH) with few products detected below 40% RH and a maximum reactive uptake coefficient of γ = (5.6 ± 0.5) × 10-5 measured at 81.2% RH. We also performed quantum chemical calculations mapping out several reaction pathways for the homogeneous ozonolysis of gaseous catechol. 1,3-cycloaddition transition states were rate limiting with the most favorable activation energies at 45.4 and 47.1 kJ mol-1 [CCSD(T)/6-311++G(d,p)] corresponding to addition across and adjacent to the diol Cdbnd C, respectively. Gas-phase rate constants, calculated using transition state theory, were six orders of magnitude slower than experimental values. In contrast, a calculated activation energy was lower for the ozonolysis of a catechol•H2O complex, which serves as a first-approximation for modeling the ozonolysis of condensed-phase catechol. These combined results suggests that homogeneous ozonolysis of catechol may not be important for the formation of secondary organic aerosols but that ozonolysis of surface-adsorbed catechol may contribute to SOA growth.

  16. Isolation and characterization of two novel halotolerant Catechol 2, 3-dioxygenases from a halophilic bacterial consortium

    NASA Astrophysics Data System (ADS)

    Guo, Guang; Fang, Tingting; Wang, Chongyang; Huang, Yong; Tian, Fang; Cui, Qijia; Wang, Hui

    2015-12-01

    Study of enzymes in halophiles will help to understand the mechanism of aromatic hydrocarbons degradation in saline environment. In this study, two novel catechol 2,3-dioxygenases (C23O1 and C23O2) were cloned and overexpressed from a halophilic bacterial consortium enriched from an oil-contaminated saline soil. Phylogenetic analysis indicated that the novel C23Os and their relatives formed a new branch in subfamily I.2.A of extradiol dioxygenases and the sequence differences were further analyzed by amino acid sequence alignment. Two enzymes with the halotolerant feature were active over a range of 0-30% salinity and they performed more stable at high salinity than in the absence of salt. Surface electrostatic potential and amino acids composition calculation suggested high acidic residues content, accounting for their tolerance to high salinity. Moreover, two enzymes were further characterized. The enzymes activity both increased in the presence of Fe3+, Fe2+, Cu2+ and Al3+ and showed no significant inhibition by other tested metal ions. The optimal temperatures for the C23Os were 40 °C and 60 °C and their best substrates were catechol and 4-methylcatechol respectively. As the firstly isolated and characterized catechol dioxygenases from halophiles, the two halotolerant C23Os presented novel characteristics suggesting their potential application in aromatic hydrocarbons biodegradation.

  17. Isolation and characterization of two novel halotolerant Catechol 2, 3-dioxygenases from a halophilic bacterial consortium.

    PubMed

    Guo, Guang; Fang, Tingting; Wang, Chongyang; Huang, Yong; Tian, Fang; Cui, Qijia; Wang, Hui

    2015-01-01

    Study of enzymes in halophiles will help to understand the mechanism of aromatic hydrocarbons degradation in saline environment. In this study, two novel catechol 2,3-dioxygenases (C23O1 and C23O2) were cloned and overexpressed from a halophilic bacterial consortium enriched from an oil-contaminated saline soil. Phylogenetic analysis indicated that the novel C23Os and their relatives formed a new branch in subfamily I.2.A of extradiol dioxygenases and the sequence differences were further analyzed by amino acid sequence alignment. Two enzymes with the halotolerant feature were active over a range of 0-30% salinity and they performed more stable at high salinity than in the absence of salt. Surface electrostatic potential and amino acids composition calculation suggested high acidic residues content, accounting for their tolerance to high salinity. Moreover, two enzymes were further characterized. The enzymes activity both increased in the presence of Fe(3+), Fe(2+), Cu(2+) and Al(3+) and showed no significant inhibition by other tested metal ions. The optimal temperatures for the C23Os were 40 °C and 60 °C and their best substrates were catechol and 4-methylcatechol respectively. As the firstly isolated and characterized catechol dioxygenases from halophiles, the two halotolerant C23Os presented novel characteristics suggesting their potential application in aromatic hydrocarbons biodegradation. PMID:26621792

  18. Isolation and characterization of two novel halotolerant Catechol 2, 3-dioxygenases from a halophilic bacterial consortium

    PubMed Central

    Guo, Guang; Fang, Tingting; Wang, Chongyang; Huang, Yong; Tian, Fang; Cui, Qijia; Wang, Hui

    2015-01-01

    Study of enzymes in halophiles will help to understand the mechanism of aromatic hydrocarbons degradation in saline environment. In this study, two novel catechol 2,3-dioxygenases (C23O1 and C23O2) were cloned and overexpressed from a halophilic bacterial consortium enriched from an oil-contaminated saline soil. Phylogenetic analysis indicated that the novel C23Os and their relatives formed a new branch in subfamily I.2.A of extradiol dioxygenases and the sequence differences were further analyzed by amino acid sequence alignment. Two enzymes with the halotolerant feature were active over a range of 0–30% salinity and they performed more stable at high salinity than in the absence of salt. Surface electrostatic potential and amino acids composition calculation suggested high acidic residues content, accounting for their tolerance to high salinity. Moreover, two enzymes were further characterized. The enzymes activity both increased in the presence of Fe3+, Fe2+, Cu2+ and Al3+ and showed no significant inhibition by other tested metal ions. The optimal temperatures for the C23Os were 40 °C and 60 °C and their best substrates were catechol and 4-methylcatechol respectively. As the firstly isolated and characterized catechol dioxygenases from halophiles, the two halotolerant C23Os presented novel characteristics suggesting their potential application in aromatic hydrocarbons biodegradation. PMID:26621792

  19. Antiplatelet Effect of Catechol Is Related to Inhibition of Cyclooxygenase, Reactive Oxygen Species, ERK/p38 Signaling and Thromboxane A2 Production

    PubMed Central

    Wang, Tong-Mei; Lin, Bor-Ru; Yeung, Sin-Yuet; Yeh, Chien-Yang; Cheng, Ru-Hsiu; Jeng, Jiiang-Huei

    2014-01-01

    Catechol (benzenediol) is present in plant-derived products, such as vegetables, fruits, coffee, tea, wine, areca nut and cigarette smoke. Because platelet dysfunction is a risk factor of cardiovascular diseases, including stroke, atherosclerosis and myocardial infarction, the purpose of this study was to evaluate the anti-platelet and anti-inflammatory effect of catechol and its mechanisms. The effects of catechol on cyclooxygenase (COX) activity, arachidonic acid (AA)-induced aggregation, thromboxane B2 (TXB2) production, lactate dehydrogenase (LDH) release, reactive oxygen species (ROS) production and extracellular signal-regulated kinase (ERK)/p38 phosphorylation were determined in rabbit platelets. In addition, its effect on IL-1β-induced prostaglandin E2 (PGE2) production by fibroblasts was determined. The ex vivo effect of catechol on platelet aggregation was also measured. Catechol (5-25 µM) suppressed AA-induced platelet aggregation and inhibited TXB2 production at concentrations of 0.5–5 µM; however, it showed little cytotoxicity and did not alter U46619-induced platelet aggregation. Catechol (10–50 µM) suppressed COX-1 activity by 29–44% and COX-2 activity by 29–50%. It also inhibited IL-1β-induced PGE2 production, but not COX-2 expression of fibroblasts. Moreover, catechol (1–10 µM) attenuated AA-induced ROS production in platelets and phorbol myristate acetate (PMA)-induced ROS production in human polymorphonuclear leukocytes. Exposure of platelets to catechol decreased AA-induced ERK and p38 phosphorylation. Finally, intravenous administration of catechol (2.5–5 µmole/mouse) attenuated ex vivo AA-induced platelet aggregation. These results suggest that catechol exhibited anti-platelet and anti-inflammatory effects, which were mediated by inhibition of COX, ROS and TXA2 production as well as ERK/p38 phosphorylation. The anti-platelet effect of catechol was confirmed by ex vivo analysis. Exposure to catechol may affect platelet

  20. Chromium(VI) reduction by catechol(amine)s results in DNA cleavage in vitro: relevance to chromium genotoxicity.

    PubMed

    Pattison, D I; Davies, M J; Levina, A; Dixon, N E; Lay, P A

    2001-05-01

    Catechols are found extensively in nature both as essential biomolecules and as the byproducts of normal oxidative damage of amino acids and proteins. They are also present in cigarette smoke and other atmospheric pollutants. Here, the interactions of reactive species generated in Cr(VI)/catechol(amine) mixtures with plasmid DNA have been investigated to model a potential route to Cr(VI)-induced genotoxicity. Reduction of Cr(VI) by 3,4-dihydroxyphenylalanine (DOPA) (1), dopamine (2), or adrenaline (3) produces species that cause extensive DNA damage, but the products of similar reactions with catechol (4) or 4-tert-butylcatechol (5) do not damage DNA. The Cr(VI)/catechol(amine) reactions have been studied at low added H(2)O(2) concentrations, which lead to enhanced DNA cleavage with 1 and induce DNA cleavage with 4. The Cr(V) and organic intermediates generated by the reactions of Cr(VI) with 1 or 4 in the presence of H(2)O(2) were characterized by EPR spectroscopy. The detected signals were assigned to Cr(V)-catechol, Cr(V)-peroxo, and mixed Cr(V)-catechol-peroxo complexes. Oxygen consumption during the reactions of Cr(VI) with 1, 2, 4, and 5 was studied, and H(2)O(2) production was quantified. Reactions of Cr(VI) with 1 and 2, but not 4 and 5, consume considerable amounts of dissolved O(2), and give extensive H(2)O(2) production. Extents of oxygen consumption and H(2)O(2) production during the reaction of Cr(VI) with enzymatically generated 1 and N-acetyl-DOPA (from the reaction of Tyr and N-acetyl-Tyr with tyrosinase, respectively) were correlated with the DNA cleaving abilities of the products of these reactions. The reaction of Cr(VI) with enzymatically generated 1 produced significant amounts of H(2)O(2) and caused significant DNA damage, but the N-acetyl-DOPA did not. The extent of in vitro DNA damage is reduced considerably by treatment of the Cr(VI)/catechol(amine) mixtures with catalase, which shows that the DNA damage is H(2)O(2)-dependent and that the

  1. DNA integrity of onion root cells under catechol influence.

    PubMed

    Petriccione, Milena; Forte, Valentina; Valente, Diego; Ciniglia, Claudia

    2013-07-01

    Catechol is a highly toxic organic pollutant, usually abundant in the waste effluents of industrial processes and agricultural activities. The environmental sources of catechol include pesticides, wood preservatives, tanning lotion, cosmetic creams, dyes, and synthetic intermediates. Genotoxicity of catechol at a concentration range 5 × 10(-1)-5 mM was evaluated by applying random amplified polymorphic DNA (RAPD) and time-lapse DNA laddering tests using onion (Allium cepa) root cells as the assay system. RAPD analysis revealed polymorphisms in the nucleotidic sequence of DNA that reflected the genotoxic potential of catechol to provoke point mutations, or deletions, or chromosomal rearrangements. Time-lapse DNA laddering test provided evidence that catechol provoked DNA necrosis and apoptosis. Acridine orange/ethidium bromide staining could distinguish apoptotic from necrotic cells in root cells of A. cepa.

  2. Photocatalytic reaction of catechol on rutile titanium oxide

    NASA Astrophysics Data System (ADS)

    Jacobson, Peter; Wang, Chundao; Diebold, Ulrike

    2008-03-01

    In an attempt to understand the fundamental aspects of photocatalysis we have studied the substituted benzene catechol on TiO2(110). Previous studies have given detailed information about the catechol bonding configuration letting our group focus on molecular level interactions with scanning tunneling microscopy and X ray photoelectron spectroscopy. Under UV exposure (248 nm) in an oxygen background, catechol is observed to degrade via oxidation. This oxidation process results in removal of roughly 10% of the initial monolayer. The removal of carbon from the TiO2 surface is shown to depend upon the background gas. Formation of a residual carbon layer is achieved by annealing the catechol monolayer to 600C. This carbon layer is more difficult to remove by photocatalytic oxidation than a pristine catechol monolayer. Work supported by Intel Corporation

  3. New Hybrid Properties of TiO2 Nanoparticles Surface Modified With Catecholate Type Ligands

    PubMed Central

    2010-01-01

    Surface modification of nanocrystalline TiO2 particles (45 Å) with bidentate benzene derivatives (catechol, pyrogallol, and gallic acid) was found to alter optical properties of nanoparticles. The formation of the inner-sphere charge–transfer complexes results in a red shift of the semiconductor absorption compared to unmodified nanocrystallites. The binding structures were investigated by using FTIR spectroscopy. The investigated ligands have the optimal geometry for chelating surface Ti atoms, resulting in ring coordination complexes (catecholate type of binuclear bidentate binding–bridging) thus restoring in six-coordinated octahedral geometry of surface Ti atoms. From the Benesi–Hildebrand plot, the stability constants at pH 2 of the order 103 M−1 have been determined. PMID:20652142

  4. New Hybrid Properties of TiO2 Nanoparticles Surface Modified With Catecholate Type Ligands

    NASA Astrophysics Data System (ADS)

    Janković, Ivana A.; Šaponjić, Zoran V.; Džunuzović, Enis S.; Nedeljković, Jovan M.

    2010-01-01

    Surface modification of nanocrystalline TiO2 particles (45 Å) with bidentate benzene derivatives (catechol, pyrogallol, and gallic acid) was found to alter optical properties of nanoparticles. The formation of the inner-sphere charge-transfer complexes results in a red shift of the semiconductor absorption compared to unmodified nanocrystallites. The binding structures were investigated by using FTIR spectroscopy. The investigated ligands have the optimal geometry for chelating surface Ti atoms, resulting in ring coordination complexes (catecholate type of binuclear bidentate binding-bridging) thus restoring in six-coordinated octahedral geometry of surface Ti atoms. From the Benesi-Hildebrand plot, the stability constants at pH 2 of the order 103 M-1 have been determined.

  5. Regiocomplementary O-Methylation of Catechols by Using Three-Enzyme Cascades.

    PubMed

    Siegrist, Jutta; Aschwanden, Simon; Mordhorst, Silja; Thöny-Meyer, Linda; Richter, Michael; Andexer, Jennifer N

    2015-12-01

    S-Adenosylmethionine (SAM)-dependent enzymes have great potential for selective alkylation processes. In this study we investigated the regiocomplementary O-methylation of catechols. Enzymatic methylation is often hampered by the need for a stoichiometric supply of SAM and the inhibitory effect of the SAM-derived byproduct on most methyltransferases. To counteract these issues we set up an enzyme cascade. Firstly, SAM was generated from l-methionine and ATP by use of an archaeal methionine adenosyltransferase. Secondly, 4-O-methylation of the substrates dopamine and dihydrocaffeic acid was achieved by use of SafC from the saframycin biosynthesis pathway in 40-70 % yield and high selectivity. The regiocomplementary 3-O-methylation was catalysed by catechol O-methyltransferase from rat. Thirdly, the beneficial influence of a nucleosidase on the overall conversion was demonstrated. The results of this study are important milestones on the pathway to catalytic SAM-dependent alkylation processes.

  6. Regiocomplementary O-Methylation of Catechols by Using Three-Enzyme Cascades.

    PubMed

    Siegrist, Jutta; Aschwanden, Simon; Mordhorst, Silja; Thöny-Meyer, Linda; Richter, Michael; Andexer, Jennifer N

    2015-12-01

    S-Adenosylmethionine (SAM)-dependent enzymes have great potential for selective alkylation processes. In this study we investigated the regiocomplementary O-methylation of catechols. Enzymatic methylation is often hampered by the need for a stoichiometric supply of SAM and the inhibitory effect of the SAM-derived byproduct on most methyltransferases. To counteract these issues we set up an enzyme cascade. Firstly, SAM was generated from l-methionine and ATP by use of an archaeal methionine adenosyltransferase. Secondly, 4-O-methylation of the substrates dopamine and dihydrocaffeic acid was achieved by use of SafC from the saframycin biosynthesis pathway in 40-70 % yield and high selectivity. The regiocomplementary 3-O-methylation was catalysed by catechol O-methyltransferase from rat. Thirdly, the beneficial influence of a nucleosidase on the overall conversion was demonstrated. The results of this study are important milestones on the pathway to catalytic SAM-dependent alkylation processes. PMID:26437744

  7. A spectroscopic and electrochemical approach to the study of the interactions and photoinduced electron transfer between catechol and anatase nanoparticles in aqueous solution.

    PubMed

    Lana-Villarreal, Teresa; Rodes, Antonio; Pérez, Juan M; Gómez, Roberto

    2005-09-14

    We have combined in situ photoelectrochemical and spectroscopic techniques (Attenuated Total Reflection Infrared, ATR-IR, and Resonance Raman Spectroscopy) for the study of the charge-transfer complex formed upon adsorption of catechol on anatase nanoparticles in contact with aqueous acidic solutions. Vibrational spectroscopies reveal the existence of at least two adsorbate configurations: catecholate in a chelate configuration and molecularly adsorbed catechol, with apparent values of -12.3 and -10.5 kJ mol(-1), respectively. These values are significantly less negative than the values reported for anatase colloidal dispersions. The adsorption of both catechol species on the nanoparticulate anatase thin films follows the Freundlich isotherm. As revealed by resonance Raman spectroscopy, only the adsorbed chelating catecholate forms the charge-transfer complex. The electron transfer from the adsorbate to the anatase nanoparticles has been evidenced by the development of a negative photopotential upon 514.5 or 632.8 nm laser illumination of an anatase nanostructured thin film electrode in contact with a catechol solution. The time evolution of the Raman spectra shows an increasing fluorescence indicating that, upon electron injection, catechol polymerization occurs on the TiO2 surfaces. This conclusion is confirmed by in situ ATR-IR measurements, which show a progressive broadening of the catecholate bands together with the appearance of new signals. This study illustrates the benefits of combining electrochemical, infrared, and Raman techniques for the elucidation of processes occurring at the semiconductor/solution interface. Finally, evidence is given on the different adsorption and reactivity behavior found for suspensions and nanoporous thin films under equivalent experimental conditions.

  8. Catechol estrogens: presence in brain and endocrine tissues.

    PubMed

    Paul, S M; Axelrod, J

    1977-08-12

    Catechol estrogens have been identified and measured in rat brain and various endocrine tissues with the use of a sensitive radioenzymatic assay. The specificity of this assay was confirmed by thin-layer chromatography and mass spectral analysis of the reaction products. The concentration of catechol estrogens in the hypothalamus and pituitary are at least ten times higher than reported previously for the parent estrogens. Catechol estrogens have potent endocrine effects and, because of their normal occurrence in the hypothalamic-pituitary axis, they have an important role in neuroendocrine regulation.

  9. Bioinspired catecholic copolymers for antifouling surface coatings.

    PubMed

    Cho, Joon Hee; Shanmuganathan, Kadhiravan; Ellison, Christopher J

    2013-05-01

    We report here a synthetic approach to prepare poly(methyl methacrylate)-polydopamine diblock (PMMA-PDA) and triblock (PDA-PMMA-PDA) copolymers combining mussel-inspired catecholic oxidative chemistry and atom transfer radical polymerization (ATRP). These copolymers display very good solubility in a range of organic solvents and also a broad band photo absorbance that increases with increasing PDA content in the copolymer. Spin-cast thin films of the copolymer were stable in water and showed a sharp reduction (by up to 50%) in protein adsorption compared to those of neat PMMA. Also the peak decomposition temperature of the copolymers was up to 43°C higher than neat PMMA. The enhanced solvent processability, thermal stability and low protein adsorption characteristics of this copolymer makes it attractive for variety of applications including antifouling coatings on large surfaces such as ship hulls, buoys, and wave energy converters.

  10. Catechol Formation and Melanization by Na+ -Dependent Azotobacter chroococcum: a Protective Mechanism for Aeroadaptation?

    PubMed Central

    Shivprasad, Shailaja; Page, William J.

    1989-01-01

    Aeroadaptive microaerophilic Azotobacter chroococcum 184 produced a cell-associated black pigment when grown at high aeration rates under nitrogen-fixing conditions. This pigment was shown to be a catechol melanin. Polyphenol oxidase activity was detected in cell extracts of cells grown for 72 h. Melanin formation was optimal in the later stages of growth, and there was no correlation between nitrogenase activity and melanization. Nitrogenase activity in strain 184 was optimal at 10% O2, and melanin formation was suppressed by O2 limitation. In the presence of charcoal, an adsorbent of toxic oxygen intermediates, and benzoic acid, a scavenger of hydroxyl radicals, melanization was inhibited. However, in the presence of copper, the intensity of pigment color increased and melanization was accelerated. Copper also eliminated catalase and peroxidase activities of the organism but still permitted aerobic growth. In the presence of low levels of iron, melanization was accelerated under high aeration rates, and under low rates of aeration, melanization was observed only at higher levels of iron. Hydroxamate-siderophore production was detectable in the presence of soluble iron under high rates of aeration but was repressed by the same levels of iron under low aeration rates. Unlike melanization and hydroxamate formation, catechol formation was observed under both low and high rates of aeration under nitrogen-fixing conditions. Catechol formation and melanization were repressed by 14 mM NH4+, at which level nitrogenase activity was also repressed. Copper reversed the repressive effect of NH4+. A role for catechol formation and melanization in aeroadaptation is proposed. PMID:16347974

  11. Reactive oxygen species production by catechol stabilized copper nanoparticles.

    PubMed

    Chen, Cheng; Ahmed, Ishtiaq; Fruk, Ljiljana

    2013-12-01

    Stable Cu nanoparticles (NPs) prepared using catechol containing dopamine-based linkers could generate reactive oxygen species (ROS) that can activate peroxidase enzymes and catalyze the degradation of fluorescent dye pollutants.

  12. Synthesis of catechol estrogens by human uterus and leiomyoma

    SciTech Connect

    Reddy, V.V.; Hanjani, P.; Rajan, R.

    1981-02-01

    Homogenates of human endometrial, myometrial and leiomyoma tissues were incubated with (2,4,6,7-/sub 3/H)-estradiol and tritiated catechol estrogens were isolated and identified. Though 2- and 4-hydroxylations were about the same in endometrium, 4-hydroxylation was two to four fold higher than 2-hydroxylation in myometrium and leiomyoma. However, endometrium showed greater capacity to form both 2- and 4-hydroxyestrogens than the other two tissues. Both 2- and 4-hydroxylations were significantly less than in myometrium. In view of the reports indicating that inhibitors of catechol 0-methyl transferase (COMT) might act as antineoplastic agents due to their interference with t-RNA methylases and since catechol estrogens inhibit COMT, the present results suggest that endogenous synthesis of catechol estrogens may play an important role in the pathophysiology of uterine leiomyoma.

  13. Degradation of Phenolic Compounds and Ring Cleavage of Catechol by Phanerochaete chrysosporium

    PubMed Central

    Leatham, Gary F.; Crawford, R. L.; Kirk, T. Kent

    1983-01-01

    POL-88, a mutant of the white-rot fungus Phanerochaete chrysosporium, was selected for diminished phenol-oxidizing enzyme activity. A wide variety of phenolic compounds were degraded by ligninolytic cultures of this mutant. With several o-diphenolic substrates, degradation intermediates were produced that had UV spectra consistent with muconic acids. Extensive spectrophotometric and polarographic assays failed to detect classical ring-cleaving dioxygenases in cell homogenates or in extracts from ligninolytic cultures. Even so, a sensitive carrier-trapping assay showed that intact cultures degraded [U-14C]catechol to [14C]muconic acid, establishing the presence of a system capable of 1,2-intradiol fission. Significant accumulation of [14C]muconic acid into carrier occurred only when evolution of 14CO2 from [14C]catechol was inhibited by treating cultures with excess nutrient nitrogen (e.g., l-glutamic acid) or with cycloheximide. l-Glutamic acid is known from past work to repress the ligninolytic system in P. chrysosporium and to mimic the effect of cycloheximide. The results here indicate, therefore, that the enzyme system responsible for degrading ring-cleavage products to CO2 turns over faster than does the system responsible for ring cleavage. PMID:16346340

  14. A smartphone-based colorimetric reader coupled with a remote server for rapid on-site catechols analysis.

    PubMed

    Wang, Yun; Li, Yuanyuan; Bao, Xu; Han, Juan; Xia, Jinchen; Tian, Xiaoyu; Ni, Liang

    2016-11-01

    The search of a practical method to analyze cis-diol-containing compounds outside laboratory settings remains a substantial scientific challenge. Herein, a smartphone-based colorimetric reader was coupled with a remote server for rapid on-site analysis of catechols. A smallest-scale 2×2 colorimetric sensor array composed of pH indicators and phenylboronic acid was configured. The array was able to distinguish 13 catechols at 6 serial concentrations, through simultaneous treatment via principal component analysis, hierarchical cluster analysis, and linear discriminant analysis. After both the discriminatory power of the array and the prediction ability of the partial least squares quantitative models were proved to be predominant, the smartphone was coupled to the remote server. All the ΔRGB data were uploaded to the remote server wherein linear discriminant analysis and partial least squares processing modules were established to provide qualitative discrimination and quantitative calculation, respectively, of the analytes in real time. The applicability of this novel method to a real-life scenario was confirmed by the on-site analysis of various catechols from a water sample of the Yangtze River; the feedback result in the smartphone showed the method was able to identify the catechols with 100% accuracy and predict the concentrations to within 0.706-2.240 standard deviation. PMID:27591604

  15. Genotoxicity and inactivation of catechol metabolites of the mycotoxin zearalenone.

    PubMed

    Fleck, Stefanie C; Hildebrand, Andreas A; Müller, Elisabeth; Pfeiffer, Erika; Metzler, Manfred

    2012-11-01

    Zearalenone (ZEN) is a highly estrogenic mycotoxin produced by Fusarium species. The adverse effects of ZEN and its reductive metabolite α-zearalenol (α-ZEL) are often compared to those of 17β-estradiol (E2) and estrone (E1). These endogenous steroidal estrogens are associated with an increased risk for cancer, which may be mediated by two mechanisms, i.e. (1) hormonal activity and (2) genotoxic effects after cytochrome P450-catalyzed metabolic activation to catechols. Like E1 and E2, ZEN and α-ZEL exhibit marked estrogenicity and also undergo aromatic hydroxylation to catechol metabolites. The subsequent methylation of catechols by catechol-O-methyltransferase (COMT) is generally considered as a detoxifying pathway. Imbalances between the activation and inactivation reactions can lead to the formation of reactive semiquinones and quinones, which can alkylate DNA or produce reactive oxygen species by redox cycling. In the present study, the genotoxicity of the catechol metabolites of ZEN, α-ZEL, E1 and E2 was determined in a cell-free system by measuring 8-oxo-2'-deoxyguanosine using a LC-DAD-MS(2) method. Each of the individual catechols of ZEN, α-ZEL, E1 and E2 induced oxidative DNA damage in calf thymus DNA. The ranking order of the DNA damaging activity was 15-hydroxy-ZEN/α-ZEL ≈ 2/4-hydroxy-E1/E2 > 13-hydroxy-ZEN/α-ZEL. When hepatic microsomes from different species were incubated with ZEN, the rat had the highest activity for catechol formation, followed by human, mouse, pig and steer. The amount of catechol metabolites correlated directly with the amount of oxidative damage in calf thymus DNA. The ranking order for the rate of methylation by human hepatic COMT was 2-hydroxy-E1/E2 > 4-hydroxy-E1/E2 > 13/15-hydroxy-ZEN/α-ZEL. Thus, the catechol metabolites of the mycoestrogen ZEN and its reductive metabolite α-ZEL exhibit a DNA-damaging potential comparable to that of the catechol metabolites of E1 and E2, but are much poorer substrates for

  16. Assessment of genotoxicity of catecholics using impedimetric DNA-biosensor.

    PubMed

    Ensafi, Ali A; Amini, Maryam; Rezaei, B

    2014-03-15

    The potential toxicity of catecholics is a big concern, because the catechol-derived semiquinone radical after the oxidation of catechol (CA) can donate an H-atom to generate quinone, and during this process a superoxide anion radical may be produced. Considering the fact that catecholics are highly consumed in our daily life and some drugs also contain one or more CA moieties, we speculate that CA's toxicity might not be insurmountable. Therefore, finding approaches to investigate catecholics potential toxicity is of great significance. Here in, an electrochemical protocol for direct monitoring of genotoxicity of catecholics is described. CA encapsulated on MWCNTs (CA@MWCNT) through continuous cyclic voltammetric on the surface of pencil graphite electrode (PGE). Subsequently, a DNA functionalized biosensor (DNA/CA@MWCNT/PGE) was prepared and characterized for the detection and the investigation of DNA damage induced by radicals generated from catecholics. The change in the charge transfer resistance (Rct) after the incubation of the DNA biosensor in the damaging solution for a certain time was used as an indicator for DNA damage. Incubation of DNA-modified electrode with CA solution containing Cu(II), Cr(VI) and Fe(III) has been shown to result in oxidative damage to the DNA and change in the electrochemical properties. It was found that the presence of Cu(II), Cr(VI) and Fe(III) in solution caused damage to DNA. The inhibitory effect of glutathione and plumbagin on the CA-mediated DNA damage has also been investigated using the biosensor. The minimum concentration of the metal ions for CA induced DNA damage was investigated. Recognition of suitable matrixes for CA-mediated DNA damage can be assessed using proposed DNA biosensor. Such direct monitoring of the DNA damage holds great promise for designing new biosensors with modification of the biosensor with different damaging agents. PMID:24121207

  17. Human catechol-O-methyltransferase: Cloning and expression of the membrane-associated form

    SciTech Connect

    Bertocci, B.; Miggiano, V.; Da Prada, M.; Dembic, Z.; Lahm, H.W.; Malherbe, P. )

    1991-02-15

    A cDNA clone for human catechol-O-methyltransferase was isolated from a human hepatoma cell line (Hep G2) cDNA library by hybridization screening with a porcine cDNA probe. The cDNA clone was sequenced and found to have an insert of 1226 nucleotides. The deduced primary structure of hCOMT is composed of 271 amino acid residues with the predicted molecular mass of 30 kDa. At its N terminus it has a hydrophobic segment of 21 amino acid residues that may be responsible for insertion of hCOMT into the endoplasmic reticulum membrane. The primary structure of hCOMT exhibits high homology to the porcine partial cDNA sequence (93%). The deduced amino acid sequence contains two tryptic peptide sequences (T-22, T-33) found in porcine liver catechol-O-methyltransferase (CEMT). The coding region of hCOMT cDNA was placed under the control of the cytomegalovirus promoter to transfect human kidney 293 cells. The recombinant hCOMT was shown by immunoblot analysis to be mainly associated with the membrane fraction. RNA blot analysis revealed one COMT mRNA transcript of 1.4 kilobases in Hep G2 poly(A){sup +} RNA.

  18. Removal of arsenic compounds from spent catecholated polymer

    DOEpatents

    Fish, Richard H.

    1985-01-01

    Described is a process for removing arsenic from petroliferous derived liquids by contacting said liquid at an elevated temperature with a divinylbenzene-crosslinked polystyrene having catechol ligands anchored thereon. Also, described is a process for regenerating spent catecholated polystyrene by removal of the arsenic bound to it from contacting petroliferous liquid as described above and involves: a. treating said spent catecholated polystyrene, at a temperature in the range of about 20.degree. to 100.degree. C. with an aqueous solution of at least one carbonate and/or bicarbonate of ammonium, alkali and alkaline earth metals, said solution having a pH between about 8 and 10 and, b. separating the solids and liquids from each other. Preferably the regeneration treatment is in two steps wherein step (a) is carried out with an aqueous alcoholic carbonate solution containing lower alkyl alcohol, and, steps (a) and (b) are repeated using a bicarbonate.

  19. Reactive oxygen species production by catechol stabilized copper nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Cheng; Ahmed, Ishtiaq; Fruk, Ljiljana

    2013-11-01

    Stable Cu nanoparticles (NPs) prepared using catechol containing dopamine-based linkers could generate reactive oxygen species (ROS) that can activate peroxidase enzymes and catalyze the degradation of fluorescent dye pollutants.Stable Cu nanoparticles (NPs) prepared using catechol containing dopamine-based linkers could generate reactive oxygen species (ROS) that can activate peroxidase enzymes and catalyze the degradation of fluorescent dye pollutants. Electronic supplementary information (ESI) available: Details of the synthesis of dopamine linkers and Cu NPs, peroxidase activity tests, H2O2 calibration and degradation tests for resorufin, RB and MB. See DOI: 10.1039/c3nr03563h

  20. Suicide inactivation of catechol 2,3-dioxygenase from Pseudomonas putida mt-2 by 3-halocatechols

    SciTech Connect

    Bartels, I.; Knackmuss, H.J.; Reineke, W.

    1984-03-01

    The inactivation of catechol 2,3-dioxygenase from Pseudomonas putida mt-2 by 3-chloro- and 3-fluorocatechol and the iron-chelating agent Tiron (catechol-3,5-disulfonate) was studied. Whereas inactivation by Tiron is an oxygen-independent and mostly reversible process, inactivation by the 3-halocatechols was only observed in the presence of oxygen and was largely irreversible. The rate constants for inactivation (K/sub 2/) were 1.62 x 10/sup -3/ sec/sup -1/ for 3-chlorocatechol and 2.38 x 10/sup -3/ sec/sup -1/ for 3-fluorocatechol. The inhibitor constants (K/sub i/) were 23 ..mu..M for 3-chlorocatechol and 17 ..mu..M for 3-fluorocatechol. The kinetic data for 3-fluorocatechol could only be obtained in the presence of 2-mercaptoethanol. Besides inactivated enzyme, some 2-hydroxyhexa-2,4-dienoic acid as the actual suicide product of meta-cleavage. A side product of 3-fluorocatechol cleavage is a yellow compound with the spectral characteristics of a 2-hydroxy-6-oxohexa-2,4-dienoci acid indicating 1,6-cleavage. Rates of inactivation by 3-fluorocatechol were reduced in the presence of superoxide dismutase, catalase, formate, and mannitol, which implies that superoxide anion, hydrogen peroxide, and hydroxyl radical exhibit additional inactivation. 64 references.

  1. Linkage between Catecholate Siderophores and the Multicopper Oxidase CueO in Escherichia coli

    PubMed Central

    Grass, Gregor; Thakali, Keshari; Klebba, Phillip E.; Thieme, Daniel; Müller, Axel; Wildner, Günter F.; Rensing, Christopher

    2004-01-01

    The multicopper oxidase CueO had previously been demonstrated to exhibit phenoloxidase activity and was implicated in intrinsic copper resistance in Escherichia coli. Catecholates can potentially reduce Cu(II) to the prooxidant Cu(I). In this report we provide evidence that CueO protects E. coli cells by oxidizing enterobactin, the catechol iron siderophore of E. coli, in the presence of copper. In vitro, a mixture of enterobactin and copper was toxic for E. coli cells, but the addition of purified CueO led to their survival. Deletion of fur resulted in copper hypersensitivity that was alleviated by additional deletion of entC, preventing synthesis of enterobactin. In addition, copper added together with 2,3-dihydroxybenzoic acid or enterobactin was able to induce a Φ(cueO-lacZ) operon fusion more efficiently than copper alone. The reaction product of the 2,3-dihydroxybenzoic acid oxidation by CueO that can complex Cu(II) ions was determined by gas chromatography-mass spectroscopy and identified as 2-carboxymuconate. PMID:15317788

  2. Sonolytic hydrolysis of peptides in aqueous solution upon addition of catechol.

    PubMed

    Sakakura, M; Takayama, M

    2009-03-01

    The sonolytic hydrolysis of peptides with addition of phenolic reagents to aqueous solutions is described. Sonolysis of an aqueous solution of peptides to which catechol (o-dihydroxybenzene) had been added resulted in hydrolytic products reflecting the amino acid sequence without any side reactions, while sonolysis without any additives resulted in oxidation analytes and degradation products caused by side reactions. Although the use of additives such as resorcinol (m-dihydroxybenzene), hydroquinone (p-dihydroxybenzene) and phenol was also effective in producing sequence related products, several degradation products were produced by side reactions. A characteristic of the sonolysis of peptides is that the N-terminal side of proline, Xxx-Pro, is more susceptible than other amino acid residues to the process. This characteristic of sonolysis is superior to that of acid hydrolysis in which cleavage at the C-terminal side of proline, Pro-Xxx is difficult, and where dehydration products result due to side reactions.

  3. A highly sensitive electrochemical biosensor for catechol using conducting polymer reduced graphene oxide-metal oxide enzyme modified electrode.

    PubMed

    Sethuraman, V; Muthuraja, P; Anandha Raj, J; Manisankar, P

    2016-10-15

    The fabrication, characterization and analytical performances were investigated for a catechol biosensor, based on the PEDOT-rGO-Fe2O3-PPO composite modified glassy carbon (GC) electrode. The graphene oxide (GO) doped conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) was prepared through electrochemical polymerization by potential cycling. Reduction of PEDOT-GO was carried out by amperometric method. Fe2O3 nanoparticles were synthesized in ethanol by hydrothermal method. The mixture of Fe2O3, PPO and glutaraldehyde was casted on the PEDOT-rGO electrode. The surface morphology of the modified electrodes was studied by FE-SEM and AFM. Cyclic voltammetric studies of catechol on the enzyme modified electrode revealed higher reduction peak current. Determination of catechol was carried out successfully by Differential Pulse Voltammetry (DPV) technique. The fabricated biosensor investigated shows a maximum current response at pH 6.5. The catechol biosensor exhibited wide sensing linear range from 4×10(-8) to 6.20×10(-5)M, lower detection limit of 7×10(-9)M, current maxima (Imax) of 92.55µA and Michaelis-Menten (Km) constant of 30.48µM. The activation energy (Ea) of enzyme electrode is 35.93KJmol(-1) at 50°C. There is no interference from d-glucose and l-glutamic acid, ascorbic acid and o-nitrophenol. The PEDOT-rGO-Fe2O3-PPO biosensor was stable for at least 75 days when stored in a buffer at about 4°C. PMID:26751827

  4. 40 CFR 721.10711 - Alkyl substituted catechol (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10711 Alkyl substituted catechol (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as...

  5. Mass spectrometric analysis of catechol-histidine adducts from insect cuticle.

    PubMed

    Kerwin, J L; Turecek, F; Xu, R; Kramer, K J; Hopkins, T L; Gatlin, C L; Yates, J R

    1999-03-15

    Adducts of catechols and histidine, which are produced by reactions of 1,2-quinones and p-quinone methides with histidyl residues in proteins incorporated into the insect exoskeleton, were characterized using electrospray ionization mass spectrometry (ESMS), tandem electrospray mass spectrometry (ESMS-MS, collision-induced dissociation), and ion trap mass spectrometry (ITMS). Compounds examined included adducts obtained from acid hydrolysates of Manduca sexta (tobacco hornworm) pupal cuticle exuviae and products obtained from model reactions under defined conditions. The ESMS and ITMS spectra of 6-(N-3')-histidyldopamine [6-(N-3')-His-DA, pi isomer] isolated from M. sexta cuticle were dominated by a [M + H]+ ion at m/z 308, rather than the expected m/z 307. High-resolution fast atom bombardment MS yielded an empirical formula of C14H18N3O5, which was consistent with this compound being 6-(N-1')-histidyl-2-(3, 4-dihydroxyphenyl)ethanol [6-(N-1')-His-DOPET] instead of a DA adduct. Similar results were obtained when histidyl-catechol compounds linked at C-7 of the catechol were examined; the (N-1') isomer was confirmed as a DA adduct, and the (N-3') isomer identified as an (N-1')-DOPET derivative. Direct MS analysis of unfractionated cuticle hydrolysate revealed intense parent and product ions characteristic of 6- and 7-linked adducts of histidine and DOPET. Mass spectrometric analysis of model adducts synthesized by electrochemical oxidative coupling of N-acetyldopamine (NADA) quinone and N-acetylhistidine (NAcH) identified the point of attachment in the two isomers. A prominent product ion corresponding to loss of CO2 from [M + H]+ of 2-NAcH-NADA confirmed this as being the (N-3') isomer. Loss of (H2O + CO) from 6-NAcH-NADA suggested that this adduct was the (N-1') isomer. The results support the hypothesis that insect cuticle sclerotization involves the formation of C-N cross-links between histidine residues in cuticular proteins, and both ring and side

  6. Tyrosinase versus Catechol Oxidase: One Asparagine Makes the Difference.

    PubMed

    Solem, Even; Tuczek, Felix; Decker, Heinz

    2016-02-18

    Tyrosinases mediate the ortho-hydroxylation and two-electron oxidation of monophenols to ortho-quinones. Catechol oxidases only catalyze the oxidation of diphenols. Although it is of significant interest, the origin of the functional discrimination between tyrosinases and catechol oxidases has been unclear. Recently, it has been postulated that a glutamate and an asparagine bind and activate a conserved water molecule towards deprotonation of monophenols. Here we demonstrate for the first time that a polyphenoloxidase, which exhibits only diphenolase activity, can be transformed to a tyrosinase by mutation to introduce an asparagine. The asparagine and a conserved glutamate are necessary to properly orient the conserved water in order to abstract a proton from the monophenol. These results provide direct evidence for the crucial importance of a proton shuttle for tyrosinase activity of type 3 copper proteins, allowing a consistent understanding of their different chemical reactivities. PMID:26773413

  7. Adsorption of catechol from aqueous solution by aminated hypercrosslinked polymers.

    PubMed

    Sun, Yue; Li, Xiao-Tao; Xu, Chao; Chen, Jin-Long; Li, Ai-Min; Zhang, Quan-Xing

    2005-01-01

    Adsorption of catechol from aqueous solution with the hypercrosslinked polymeric adsorbent NDA-100 and its derivatives AH-1, AH-2 and AH-3 aminated by dimethylamine, the commercial resin Amberlite XAD-4 and weakly basic anion exchanger resin D301 was compared. It was found that the aminated hypercrosslinked resins had the highest adsorption capacities among the tested polymers. The empirical Freundlich equation was successfully employed to describe the adsorption process. Specific surface area and micropore structure of the adsorbent, in company with tertiary amino groups on matrix affected the adsorption performance towards catechol. In addition, thermodynamic study was carried out to interpret the adsorption mechanism. Kinetic study testified that the tertiary amino groups on the polymer matrix could decrease the adsorption rate and increase the adsorption apparent activation energy.

  8. Low catechol-O-methyltransferase activity in a Saami population.

    PubMed

    Klemetsdal, B; Straume, B; Giverhaug, T; Aarbakke, J

    1994-01-01

    Catechol-O-methyltransferase (COMT) catalyzes the O-methylation of catechol hormones, neurotransmitters and certain drugs. It is subject to genetic polymorphism and ethnic differences. High red blood cell (RBC) COMT activity has been correlated with a poor response to levodopa treatment in Parkinson's disease. RBC COMT was determined in a Norwegian population (n = 213) of whom 115 were Saami (Laaps). The Saami had 16.5% lower RBC COMT activity compared to a non-Saami population sample from the northern part of Norway (n = 50), 13.9 vs. 16.4 units/ml RBC (U) (P = 0.04). This is the first report of any population with lower RBC COMT activity than a Caucasian population. A wide range of RBC COMT activities was found in the entire population examined (1.3-38.3 U).

  9. Brain catechol synthesis - Control by brain tyrosine concentration

    NASA Technical Reports Server (NTRS)

    Wurtman, R. J.; Larin, F.; Mostafapour, S.; Fernstrom, J. D.

    1974-01-01

    Brain catechol synthesis was estimated by measuring the rate at which brain dopa levels rose following decarboxylase inhibition. Dopa accumulation was accelerated by tyrosine administration, and decreased by treatments that lowered brain tyrosine concentrations (for example, intraperitoneal tryptophan, leucine, or parachlorophenylalanine). A low dose of phenylalanine elevated brain tyrosine without accelerating dopa synthesis. Our findings raise the possibility that nutritional and endocrine factors might influence brain catecholamine synthesis by controlling the availability of tyrosine.

  10. Platinum Nanoparticles: Efficient and Stable Catechol Oxidase Mimetics.

    PubMed

    Liu, Yi; Wu, Haohao; Chong, Yu; Wamer, Wayne G; Xia, Qingsu; Cai, Lining; Nie, Zhihong; Fu, Peter P; Yin, Jun-Jie

    2015-09-01

    Although enzyme-like nanomaterials have been extensively investigated over the past decade, most research has focused on the peroxidase-like, catalase-like, or SOD-like activity of these nanomaterials. Identifying nanomaterials having oxidase-like activities has received less attention. In this study, we demonstrate that platinum nanoparticles (Pt NPs) exhibit catechol oxidase-like activity, oxidizing polyphenols into the corresponding o-quinones. Four unique approaches are employed to demonstrate the catechol oxidase-like activity exerted by Pt NPs. First, UV-vis spectroscopy is used to monitor the oxidation of polyphenols catalyzed by Pt NPs. Second, the oxidized products of polyphenols are identified by ultrahigh-performance liquid chromatography (UHPLC) separation followed by high-resolution mass spectrometry (HRMS) identification. Third, electron spin resonance (ESR) oximetry techniques are used to confirm the O2 consumption during the oxidation reaction. Fourth, the intermediate products of semiquinone radicals formed during the oxidation of polyphenols are determined by ESR using spin stabilization. These results indicate Pt NPs possess catechol oxidase-like activity. Because polyphenols and related bioactive substances have been explored as potent antioxidants that could be useful for the prevention of cancer and cardiovascular diseases, and Pt NPs have been widely used in the chemical industry and medical science, it is essential to understand the potential effects of Pt NPs for altering or influencing the antioxidant activity of polyphenols.

  11. Platinum Nanoparticles: Efficient and Stable Catechol Oxidase Mimetics.

    PubMed

    Liu, Yi; Wu, Haohao; Chong, Yu; Wamer, Wayne G; Xia, Qingsu; Cai, Lining; Nie, Zhihong; Fu, Peter P; Yin, Jun-Jie

    2015-09-01

    Although enzyme-like nanomaterials have been extensively investigated over the past decade, most research has focused on the peroxidase-like, catalase-like, or SOD-like activity of these nanomaterials. Identifying nanomaterials having oxidase-like activities has received less attention. In this study, we demonstrate that platinum nanoparticles (Pt NPs) exhibit catechol oxidase-like activity, oxidizing polyphenols into the corresponding o-quinones. Four unique approaches are employed to demonstrate the catechol oxidase-like activity exerted by Pt NPs. First, UV-vis spectroscopy is used to monitor the oxidation of polyphenols catalyzed by Pt NPs. Second, the oxidized products of polyphenols are identified by ultrahigh-performance liquid chromatography (UHPLC) separation followed by high-resolution mass spectrometry (HRMS) identification. Third, electron spin resonance (ESR) oximetry techniques are used to confirm the O2 consumption during the oxidation reaction. Fourth, the intermediate products of semiquinone radicals formed during the oxidation of polyphenols are determined by ESR using spin stabilization. These results indicate Pt NPs possess catechol oxidase-like activity. Because polyphenols and related bioactive substances have been explored as potent antioxidants that could be useful for the prevention of cancer and cardiovascular diseases, and Pt NPs have been widely used in the chemical industry and medical science, it is essential to understand the potential effects of Pt NPs for altering or influencing the antioxidant activity of polyphenols. PMID:26305170

  12. Aerosol formation yields from the reaction of catechol with ozone

    NASA Astrophysics Data System (ADS)

    Coeur-Tourneur, Cécile; Tomas, Alexandre; Guilloteau, Angélique; Henry, Françoise; Ledoux, Frédéric; Visez, Nicolas; Riffault, Véronique; Wenger, John C.; Bedjanian, Yuri

    The formation of secondary organic aerosol from the gas-phase reaction of catechol (1,2-dihydroxybenzene) with ozone has been studied in two smog chambers. Aerosol production was monitored using a scanning mobility particle sizer and loss of the precursor was determined by gas chromatography and infrared spectroscopy, whilst ozone concentrations were measured using a UV photometric analyzer. The overall organic aerosol yield ( Y) was determined as the ratio of the suspended aerosol mass corrected for wall losses ( Mo) to the total reacted catechol concentrations, assuming a particle density of 1.4 g cm -3. Analysis of the data clearly shows that Y is a strong function of Mo and that secondary organic aerosol formation can be expressed by a one-product gas-particle partitioning absorption model. The aerosol formation is affected by the initial catechol concentration, which leads to aerosol yields ranging from 17% to 86%. The results of this work are compared to similar studies reported in the literature.

  13. Catechol-O-methyltransferase as a target for melanoma destruction?

    PubMed

    Smit, N P; Latter, A J; Naish-Byfield, S; Westerhof, W; Pavel, S; Riley, P A

    1994-08-17

    Catechols may interfere in melanogenesis by causing increased levels of toxic quinones. Several catechols and known inhibitors of the enzyme catechol-O-methyltransferase (COMT) were therefore tested for their toxicity towards a pigmented melanoma cell line, UCLA-SO-(M14). The inhibition of thymidine incorporation as a result of exposure to the compounds was measured. All agents were compared to 4-hydroxyanisole (4HA), a depigmenting agent extensively studied as an antimelanoma drug. The compounds were also tested on the epithelial cell line, CNCM-I-(221) in the presence and absence of tyrosinase. All the compounds were more effective than 4HA towards the M14-cells at either 10(-4) M or 10(-5) M. The toxicity of 4HA towards the 221-cells was shown to be completely dependent on the presence of tyrosinase. Effects of the test agents on the 221-cells were also observed in the absence of tyrosinase. Although some of them were shown to be good substrates for tyrosinase only small changes in toxicity were observed as a result of the presence of the enzyme in comparison with 4HA. No direct correlation of the toxicity of the agents and COMT inhibition was observed. The possible mode of action of the compounds through inhibition of COMT and interference in melanogenesis is discussed together with other possibilities and factors involved.

  14. The role of DNA methylation in catechol-enhanced erythroid differentiation of K562 cells

    SciTech Connect

    Li, Xiao-Fei; Wu, Xiao-Rong; Xue, Ming; Wang, Yan; Wang, Jie; Li, Yang; Suriguga,; Zhang, Guang-Yao; Yi, Zong-Chun

    2012-11-15

    Catechol is one of phenolic metabolites of benzene in vivo. Catechol is also widely used in pharmaceutical and chemical industries. In addition, fruits, vegetables and cigarette smoke also contain catechol. Our precious study showed that several benzene metabolites (phenol, hydroquinone, and 1,2,4-benzenetriol) inhibited erythroid differentiation of K562 cells. In present study, the effect of catechol on erythroid differentiation of K562 cells was investigated. Moreover, to address the role of DNA methylation in catechol-induced effect on erythroid differentiation in K562 cells, methylation levels of erythroid-specific genes were analyzed by Quantitative MassARRAY methylation analysis platform. Benzidine staining showed that exposure to catechol enhanced hemin-induced hemoglobin accumulation in K562 cells in concentration- and time-dependent manners. The mRNA expression of erythroid specific genes, including α-globin, β-globin, γ-globin, erythroid 5-aminolevulinate synthase, erythroid porphobilinogen deaminase, and transcription factor GATA-1 genes, showed a significant concentration-dependent increase in catechol-treated K562 cells. The exposure to catechol caused a decrease in DNA methylation levels at a few CpG sites in some erythroid specific genes including α-globin, β-globin and erythroid porphobilinogen deaminase genes. These results indicated that catechol improved erythroid differentiation potency of K562 cells at least partly via up-regulating transcription of some erythroid related genes, and suggested that inhibition of DNA methylation might be involved in up-regulated expression of some erythroid related genes. -- Highlights: ► Catechol enhanced hemin-induced hemoglobin accumulation. ► Exposure to catechol resulted in up-regulated expression of erythroid genes. ► Catechol reduced methylation levels at some CpG sites in erythroid genes.

  15. Biological degradation of catechol in wastewater using the sequencing continuous-inflow reactor (SCR).

    PubMed

    Aghapour, Ali Ahmad; Moussavi, Gholamreza; Yaghmaeian, Kamyar

    2013-05-24

    Catechol is used in many industries. It can be removed from wastewater by various methods but biological processes are the most superior and commonly used technology. The SCR is a modified form of SBR used to degrade catechol. The objective of this study was to investigate the performance of SCR for biodegradation and mineralization of catechol under various inlet concentrations (630-1500 mg/L) and hydraulic retention times (HRT) (18-9 h). This study used a bench scale SCR setup to test catechol degradation. The acclimation time of biomass for catechol at degradation at 630 mg/L was 41 d. The SCR operating cycle time was 6 h and the consecutive times taken for aerating, settling and decanting were 4, 1.5 and 0.5 h, respectively. This study investigated the effects of inlet catechol concentration (630-1560 mg/L) and HRT (18-9 h). The average catechol removal efficiencies in steady-state conditions of 630, 930, 12954 and 1559 mg/L of catechol were 98.5%, 98.5%, 98.2% and 96.9% in terms catechol and 97.8%, 97.7%, 96.4% and 94.3% for COD, respectively. SCR with acclimated biomasses could effectively remove the catechol and the corresponding COD from wastewater with concentrations of up to 1560, at the loading rate of 5.38 kg COD/m3.d and at a HRT of up to 13 h. The HRT was determined as an important variable affecting catechol removal from wastewater. Reducing the HRT to below 13 h led to reduced removal of catechol and COD.

  16. A two-electron shell game: Intermediates of the extradiol-cleaving catechol dioxygenases

    PubMed Central

    Fielding, Andrew J.

    2014-01-01

    Extradiol catechol ring-cleaving dioxygenases function by binding both the organic substrate and O2 at a divalent metal center in the active site. They have proven to be a particularly versatile group of enzymes with which to study the O2 activation process. Here, recent studies of homoprotocatechuate 2,3-dioxygenase (HPCD) are summarized with the objective of showing how Nature can utilize the enzyme structure and the properties of the metal and the substrate to select among many possible chemical paths to achieve both specificity and efficiency. Possible intermediates in the mechanism have been trapped by swapping active site metals, introducing active site amino acid substituted variants, and using substrates with different electron donating capacities. While each of these intermediates could form part of a viable reaction pathway, kinetic measurements significantly limit the likely candidates. Structural, kinetic, spectroscopic and computational analysis of the various intermediates shed light on how catalytic efficiency can be achieved. PMID:24615282

  17. Simultaneous Detection and Estimation of Catechol, Hydroquinone, and Resorcinol in Binary and Ternary Mixtures Using Electrochemical Techniques.

    PubMed

    Hossain, Md Uzzal; Rahman, Md Toufiqur; Ehsan, Md Qamrul

    2015-01-01

    Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were performed with a glassy carbon electrode (GCE) modified with polyglutamic acid (PGA) on the three dihydroxybenzene isomers, catechol (CT), hydroquinone (HQ), and resorcinol (RS). At bare GCE, these isomers exhibited voltammograms with highly overlapped redox peaks that impeded their simultaneous detection in binary and ternary mixtures. On the contrary, at PGA modified GCE binary and ternary mixtures of the dihydroxybenzene isomers showed well-resolved redox peaks in both CV and DPV experiments. This resolving ability of PGA modified GCE proves its potential to be exploited as an electrochemical sensor for the simultaneous detection of these isomers.

  18. Simultaneous Detection and Estimation of Catechol, Hydroquinone, and Resorcinol in Binary and Ternary Mixtures Using Electrochemical Techniques

    PubMed Central

    Hossain, Md. Uzzal; Rahman, Md. Toufiqur; Ehsan, Md. Qamrul

    2015-01-01

    Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were performed with a glassy carbon electrode (GCE) modified with polyglutamic acid (PGA) on the three dihydroxybenzene isomers, catechol (CT), hydroquinone (HQ), and resorcinol (RS). At bare GCE, these isomers exhibited voltammograms with highly overlapped redox peaks that impeded their simultaneous detection in binary and ternary mixtures. On the contrary, at PGA modified GCE binary and ternary mixtures of the dihydroxybenzene isomers showed well-resolved redox peaks in both CV and DPV experiments. This resolving ability of PGA modified GCE proves its potential to be exploited as an electrochemical sensor for the simultaneous detection of these isomers. PMID:26770198

  19. Vibrational energy redistribution in catechol during ultraviolet photolysis.

    PubMed

    King, Graeme A; Oliver, Thomas A A; Dixon, Richard N; Ashfold, Michael N R

    2012-03-14

    This article reports the striking interplay between the molecular structure and the photodissociation dynamics of catechol (a key dihydroxybenzene), identified using a combination of electronic spectroscopy, hydrogen (Rydberg) atom photofragment translational spectroscopy, density functional theory and second order approximate coupled cluster methods. We describe how the non-planar (C(1) symmetry) ← planar (C(s) symmetry) geometry change during S(1) (1(1)ππ*) ←S(0) excitation in catechol, as well as the presence of internal hydrogen bonding, can perturb the photodissociation dynamics relative to that of phenol (a monohydroxybenzene), particularly with respect to O-H bond fission via the lowest dissociative (1)πσ* state. For λ(phot) > 270 nm, O-H bond fission (of the non hydrogen bonded hydroxyl moiety) is deduced to proceed via H atom tunnelling from the photo-prepared 1(1)ππ* state into the lowest (1)πσ* state of the molecule. The vibrational energy distribution in the resulting catechoxyl product changes notably as λ(phot) is tuned on resonance with either the v' = 0, m(2)' = 1(+) or m(2)' = 2(+) torsional levels of the photo-prepared 1(1)ππ* state: the product state distribution is highly sensitive to the degree of OH torsional excitation (m(2)) prepared during photo-excitation. It is deduced that such torsional excitation can be redistributed very efficiently into ring puckering (and likely also in-plane ring stretch) vibrations as the molecule tunnels to its repulsive 1(1)πσ* state and dissociates. These observations can be rationalised by consideration of the photo-prepared nuclear wavefunctions. Analysis of the product vibrational energy distribution also reveals that the O-H bond strength of the non hydrogen bonded O-H moiety in catechol, D(0)(H-catechoxyl) ≤ 27 480 ± 50 cm(-1), ∼2500 cm(-1) lower than that of the sole O-H bond in bare phenol. As a consequence, the vertical excitation energy of the 1(1)πσ* state in catechol is

  20. Conversion of trypsin to a copper enzyme: tyrosinase/catechol oxidase by chemical modification.

    PubMed

    Okutucu, Burcu; Zeytunluoglu, Ali; Zihnioglu, Figen

    2010-01-01

    New active sites can be introduced into naturally occurring enzymes by the chemical modification of specific amino acid residues in concert with genetic techniques. Chemical strategies have had a significant impact in the field of enzyme design such as modifying the selectivity and catalytic activity which is very different from those of the corresponding native enzymes. Thus, chemical modification has been exploited for the incorporation of active site binding analogs onto protein templates and for atom replacement in order to generate new functionality such as the conversion of a hydrolase into a peroxidase. The introduction of a coordination complex into a substrate binding pocket of trypsin could probably also be extended to various enzymes of significant therapeutic and biotechnological importance. The aim of this study is the conversion of trypsin into a copper enzyme: tyrosinase by chemical modification. Tyrosinase is a biocatalyst (EC.1.14.18.1) containing two atoms of copper per active site with monooxygenase activity. The active site of trypsin (EC 3.4.21.4), a serine protease was chemically modified by copper (Cu(+2)) introduced p-aminobenzamidine (pABA- Cu(+2): guanidine containing schiff base metal chelate) which exhibits affinity for the carboxylate group in the active site as trypsin-like inhibitor. Trypsin and the resultant semisynthetic enzyme preparation was analysed by means of its trypsin and catechol oxidase/tyrosinase activity. After chemical modification, trypsin-pABA-Cu(+2) preparation lost 63% of its trypsin activity and gained tyrosinase/catechol oxidase activity. The kinetic properties (K(cat), K(m), K(cat)/K(m)), optimum pH and temperature of the trypsin-pABA-Cu(+2) complex was also investigated. PMID:20024799

  1. Detection of Catechol by Potentiometric-Flow Injection Analysis in the Presence of Interferents

    ERIC Educational Resources Information Center

    Lunsford, Suzanne K.; Widera, Justyna; Zhang, Hong

    2007-01-01

    This article describes an undergraduate analytical chemistry experiment developed to teach instrumental lab skills while incorporating common interferents encountered in the real-world analysis of catechol. The lab technique incorporates potentiometric-flow injection analysis on a dibenzo-18-crown-6 dual platinum electrode to detect catechol in…

  2. Improved performance of protected catecholic polysiloxanes for bio-inspired wet adhesion to surface oxides

    PubMed Central

    Heo, Jinhwa; Kang, Taegon; Jang, Se Gyu; Hwang, Dong Soo; Spruell, Jason M.; Killops, Kato L.; Waite, J. Herbert; Hawker, Craig J.

    2012-01-01

    A facile synthetic strategy for introducing catecholic moieties into polymeric materials based on a readily available precursor – eugenol – and efficient chemistries – tris(pentafluorophenyl)borane catalyzed silation and thiol-ene coupling is reported. Silyl-protection is shown to be critical for the oxidative stability of catecholic moieties during synthesis and processing which allows functionalized polysiloxane derivatives to be fabricated into 3-D microstructures as well as 2-D patterned surfaces. Deprotection gives stable catechol surfaces with adhesion to a variety of oxide surfaces being precisely tuned by the level of catechol incorporation. The advantage of silyl-protection for catechol functionalized polysiloxanes is demonstrated and represents a promising and versatile new platform for underwater surface treatments. PMID:23181614

  3. Synthesis of tripodal catecholates and their immobilization on zinc oxide nanoparticles

    PubMed Central

    Klitsche, Franziska; Ramcke, Julian; Migenda, Julia; Hensel, Andreas; Vossmeyer, Tobias; Weller, Horst

    2015-01-01

    Summary A common approach to generate tailored materials and nanoparticles (NPs) is the formation of molecular monolayers by chemisorption of bifunctional anchor molecules. This approach depends critically on the choice of a suitable anchor group. Recently, bifunctional catecholates, inspired by mussel-adhesive proteins (MAPs) and bacterial siderophores, have received considerable interest as anchor groups for biomedically relevant metal surfaces and nanoparticles. We report here the synthesis of new tripodal catecholates as multivalent anchor molecules for immobilization on metal surfaces and nanoparticles. The tripodal catecholates have been conjugated to various effector molecules such as PEG, a sulfobetaine and an adamantyl group. The potential of these conjugates has been demonstrated with the immobilization of tripodal catecholates on ZnO NPs. The results confirmed a high loading of tripodal PEG-catecholates on the particles and the formation of stable PEG layers in aqueous solution. PMID:26124871

  4. Concerted actions of the catechol O-methyltransferase and the cytosolic sulfotransferase SULT1A3 in the metabolism of catecholic drugs.

    PubMed

    Kurogi, Katsuhisa; Alazizi, Adnan; Liu, Ming-Yih; Sakakibara, Yoichi; Suiko, Masahito; Sugahara, Takuya; Liu, Ming-Cheh

    2012-11-01

    Catecholic drugs had been reported to be metabolized through conjugation reactions, particularly methylation and sulfation. Whether and how these two Phase II conjugation reactions may occur in a concerted manner, however, remained unclear. The current study was designed to investigate the methylation and/or sulfation of five catecholic drugs. Analysis of the spent media of HepG2 cells metabolically labeled with [(35)S]sulfate in the presence of individual catecholic drugs revealed the presence of two [(35)S]sulfated metabolites for dopamine, epinephrine, isoproterenol, and isoetharine, but only one [(35)S]sulfated metabolite for apomorphine. Further analyses using tropolone, a catechol O-methyltransferase (COMT) inhibitor, indicated that one of the two [(35)S]sulfated metabolites of dopamine, epinephrine, isoproterenol, and isoetharine was a doubly conjugated (methylated and sulfated) product, since its level decreased proportionately with increasing concentrations of tropolone added to the labeling media. Moreover, while the inhibition of methylation resulted in a decrease of the total amount of [(35)S]sulfated metabolites, sulfation appeared to be capable of compensating the suppressed methylation in the metabolism of these four catecholic drugs. A two-stage enzymatic assay showed the sequential methylation and sulfation of dopamine, epinephrine, isoproterenol, and isoetharine mediated by, respectively, the COMT and the cytosolic sulfotransferase SULT1A3. Collectively, the results from the present study implied the concerted actions of the COMT and SULT1A3 in the metabolism of catecholic drugs.

  5. Mapping the conformational space accessible to catechol-O-methyltransferase.

    PubMed

    Ehler, Andreas; Benz, Jörg; Schlatter, Daniel; Rudolph, Markus G

    2014-08-01

    Methylation catalysed by catechol-O-methyltransferase (COMT) is the main pathway of catechol neurotransmitter deactivation in the prefrontal cortex. Low levels of this class of neurotransmitters are held to be causative of diseases such as schizophrenia, depression and Parkinson's disease. Inhibition of COMT may increase neurotransmitter levels, thus offering a route for treatment. Structure-based drug design hitherto seems to be based on the closed enzyme conformation. Here, a set of apo, semi-holo, holo and Michaelis form crystal structures are described that define the conformational space available to COMT and that include likely intermediates along the catalytic pathway. Domain swaps and sizeable loop movements around the active site testify to the flexibility of this enzyme, rendering COMT a difficult drug target. The low affinity of the co-substrate S-adenosylmethionine and the large conformational changes involved during catalysis highlight significant energetic investment to achieve the closed conformation. Since each conformation of COMT is a bona fide target for inhibitors, other states than the closed conformation may be promising to address. Crystallographic data for an alternative avenue of COMT inhibition, i.e. locking of the apo state by an inhibitor, are presented. The set of COMT structures may prove to be useful for the development of novel classes of inhibitors.

  6. Mapping the conformational space accessible to catechol-O-methyltransferase.

    PubMed

    Ehler, Andreas; Benz, Jörg; Schlatter, Daniel; Rudolph, Markus G

    2014-08-01

    Methylation catalysed by catechol-O-methyltransferase (COMT) is the main pathway of catechol neurotransmitter deactivation in the prefrontal cortex. Low levels of this class of neurotransmitters are held to be causative of diseases such as schizophrenia, depression and Parkinson's disease. Inhibition of COMT may increase neurotransmitter levels, thus offering a route for treatment. Structure-based drug design hitherto seems to be based on the closed enzyme conformation. Here, a set of apo, semi-holo, holo and Michaelis form crystal structures are described that define the conformational space available to COMT and that include likely intermediates along the catalytic pathway. Domain swaps and sizeable loop movements around the active site testify to the flexibility of this enzyme, rendering COMT a difficult drug target. The low affinity of the co-substrate S-adenosylmethionine and the large conformational changes involved during catalysis highlight significant energetic investment to achieve the closed conformation. Since each conformation of COMT is a bona fide target for inhibitors, other states than the closed conformation may be promising to address. Crystallographic data for an alternative avenue of COMT inhibition, i.e. locking of the apo state by an inhibitor, are presented. The set of COMT structures may prove to be useful for the development of novel classes of inhibitors. PMID:25084335

  7. Catechol-functionalized chitosan/iron oxide nanoparticle composite inspired by mussel thread coating and squid beak interfacial chemistry.

    PubMed

    Zvarec, Ondrej; Purushotham, Sreekanth; Masic, Admir; Ramanujan, Raju V; Miserez, Ali

    2013-08-27

    Biological materials offer a wide range of multifunctional and structural properties that are currently not achieved in synthetic materials. Herein we report on the synthesis and preparation of bioinspired organic/inorganic composites that mimic the key physicochemical features associated with the mechanical strengthening of both squid beaks and mussel thread coatings using chitosan as an initial template. While chitosan is a well-known biocompatible material, it suffers from key drawbacks that have limited its usage in a wider range of structural biomedical applications. First, its load-bearing capability in hydrated conditions remains poor, and second it completely dissolves at pH < 6, preventing its use in mild acidic microenvironments. In order to overcome these intrinsic limitations, a chitosan-based organic/inorganic biocomposite is prepared that mimics the interfacial chemistry of squid beaks and mussel thread coating. Chitosan was functionalized with catechol moieties in a highly controlled fashion and combined with superparamagnetic iron oxide (γ-Fe2O3) nanoparticles to give composites that represent a significant improvement in functionality of chitosan-based biomaterials. The inorganic/organic (γ-Fe2O3/catechol) interfaces are stabilized and strengthened by coordination bonding, resulting in hybrid composites with improved stability at high temperatures, physiological pH conditions, and acid/base conditions. The inclusion of superparamagnetic particles also makes the composites stimuli-responsive. PMID:23865752

  8. Entacapone and Tolcapone, Two Catechol O-Methyltransferase Inhibitors, Block Fibril Formation of α-Synuclein and β-Amyloid and Protect against Amyloid-induced Toxicity*

    PubMed Central

    Di Giovanni, Saviana; Eleuteri, Simona; Paleologou, Katerina E.; Yin, Guowei; Zweckstetter, Markus; Carrupt, Pierre-Alain; Lashuel, Hilal A.

    2010-01-01

    Parkinson disease (PD) is the second most common neurodegenerative disorder after Alzheimer disease (AD). There is considerable consensus that the increased production and/or aggregation of α-synuclein (α-syn) plays a central role in the pathogenesis of PD and related synucleinopathies. Current therapeutic strategies for treating PD offer mainly transient symptomatic relief and aim at the restitution of dopamine levels to counterbalance the loss of dopaminergic neurons. Therefore, the identification and development of drug-like molecules that block α-synuclein aggregation and prevent the loss of dopaminergic neurons are desperately needed to treat or slow the progression of PD. Here, we show that entacapone and tolcapone are potent inhibitors of α-syn and β-amyloid (Aβ) oligomerization and fibrillogenesis, and they also protect against extracellular toxicity induced by the aggregation of both proteins. Comparison of the anti-aggregation properties of entacapone and tolcapone with the effect of five other catechol-containing compounds, dopamine, pyrogallol, gallic acid, caffeic acid, and quercetin on the oligomerization and fibrillization of α-syn and Aβ, demonstrate that the catechol moiety is essential for the anti-amyloidogenic activity. Our findings present the first characterization of the anti-amyloidogenic properties of tolcapone and entacapone against both α-synuclein and Aβ42 and highlight the potential of this class of nitro-catechol compounds as anti-amyloidogenic agents. Their inhibitory properties, mode of action, and structural properties suggest that they constitute promising lead compounds for further optimization. PMID:20150427

  9. Entacapone and tolcapone, two catechol O-methyltransferase inhibitors, block fibril formation of alpha-synuclein and beta-amyloid and protect against amyloid-induced toxicity.

    PubMed

    Di Giovanni, Saviana; Eleuteri, Simona; Paleologou, Katerina E; Yin, Guowei; Zweckstetter, Markus; Carrupt, Pierre-Alain; Lashuel, Hilal A

    2010-05-14

    Parkinson disease (PD) is the second most common neurodegenerative disorder after Alzheimer disease (AD). There is considerable consensus that the increased production and/or aggregation of alpha-synuclein (alpha-syn) plays a central role in the pathogenesis of PD and related synucleinopathies. Current therapeutic strategies for treating PD offer mainly transient symptomatic relief and aim at the restitution of dopamine levels to counterbalance the loss of dopaminergic neurons. Therefore, the identification and development of drug-like molecules that block alpha-synuclein aggregation and prevent the loss of dopaminergic neurons are desperately needed to treat or slow the progression of PD. Here, we show that entacapone and tolcapone are potent inhibitors of alpha-syn and beta-amyloid (Abeta) oligomerization and fibrillogenesis, and they also protect against extracellular toxicity induced by the aggregation of both proteins. Comparison of the anti-aggregation properties of entacapone and tolcapone with the effect of five other catechol-containing compounds, dopamine, pyrogallol, gallic acid, caffeic acid, and quercetin on the oligomerization and fibrillization of alpha-syn and Abeta, demonstrate that the catechol moiety is essential for the anti-amyloidogenic activity. Our findings present the first characterization of the anti-amyloidogenic properties of tolcapone and entacapone against both alpha-synuclein and Abeta42 and highlight the potential of this class of nitro-catechol compounds as anti-amyloidogenic agents. Their inhibitory properties, mode of action, and structural properties suggest that they constitute promising lead compounds for further optimization. PMID:20150427

  10. Quinone Reductase 2 Is a Catechol Quinone Reductase

    SciTech Connect

    Fu, Yue; Buryanovskyy, Leonid; Zhang, Zhongtao

    2008-09-05

    The functions of quinone reductase 2 have eluded researchers for decades even though a genetic polymorphism is associated with various neurological disorders. Employing enzymatic studies using adrenochrome as a substrate, we show that quinone reductase 2 is specific for the reduction of adrenochrome, whereas quinone reductase 1 shows no activity. We also solved the crystal structure of quinone reductase 2 in complexes with dopamine and adrenochrome, two compounds that are structurally related to catecholamine quinones. Detailed structural analyses delineate the mechanism of quinone reductase 2 specificity toward catechol quinones in comparison with quinone reductase 1; a side-chain rotational difference between quinone reductase 1 and quinone reductase 2 of a single residue, phenylalanine 106, determines the specificity of enzymatic activities. These results infer functional differences between two homologous enzymes and indicate that quinone reductase 2 could play important roles in the regulation of catecholamine oxidation processes that may be involved in the etiology of Parkinson disease.

  11. Oxidation stability of biodiesel fuels and blends using the Rancimat and PetroOXY methods. Effect of 4-allyl-2,6-dimethoxyphenol and catechol as biodiesel additives on oxidation stability.

    PubMed

    Botella, Lucía; Bimbela, Fernando; Martín, Lorena; Arauzo, Jesús; Sánchez, José L

    2014-01-01

    IN THE PRESENT WORK, SEVERAL FATTY ACID METHYL ESTERS (FAME) HAVE BEEN SYNTHESIZED FROM VARIOUS FATTY ACID FEEDSTOCKS: used frying olive oil, pork fat, soybean, rapeseed, sunflower, and coconut. The oxidation stabilities of the biodiesel samples and of several blends have been measured simultaneously by both the Rancimat method, accepted by EN14112 standard, and the PetroOXY method, prEN16091 standard, with the aim of finding a correlation between both methodologies. Other biodiesel properties such as composition, cold filter plugging point (CFPP), flash point (FP), and kinematic viscosity have also been analyzed using standard methods in order to further characterize the biodiesel produced. In addition, the effect on the biodiesel properties of using 4-allyl-2,6-dimethoxyphenol and catechol as additives in biodiesel blends with rapeseed and with soybean has also been analyzed. The use of both antioxidants results in a considerable improvement in the oxidation stability of both types of biodiesel, especially using catechol. Adding catechol loads as low as 0.05% (m/m) in blends with soybean biodiesel and as low as 0.10% (m/m) in blends with rapeseed biodiesel is sufficient for the oxidation stabilities to comply with the restrictions established by the European EN14214 standard. An empirical linear equation is proposed to correlate the oxidation stability by the two methods, PetroOXY and Rancimat. It has been found that the presence of either catechol or 4-allyl-2,6-dimethoxyphenol as additives affects the correlation observed.

  12. Oxidation stability of biodiesel fuels and blends using the Rancimat and PetroOXY methods. Effect of 4-allyl-2,6-dimethoxyphenol and catechol as biodiesel additives on oxidation stability

    PubMed Central

    Botella, Lucía; Bimbela, Fernando; Martín, Lorena; Arauzo, Jesús; Sánchez, José L.

    2014-01-01

    In the present work, several fatty acid methyl esters (FAME) have been synthesized from various fatty acid feedstocks: used frying olive oil, pork fat, soybean, rapeseed, sunflower, and coconut. The oxidation stabilities of the biodiesel samples and of several blends have been measured simultaneously by both the Rancimat method, accepted by EN14112 standard, and the PetroOXY method, prEN16091 standard, with the aim of finding a correlation between both methodologies. Other biodiesel properties such as composition, cold filter plugging point (CFPP), flash point (FP), and kinematic viscosity have also been analyzed using standard methods in order to further characterize the biodiesel produced. In addition, the effect on the biodiesel properties of using 4-allyl-2,6-dimethoxyphenol and catechol as additives in biodiesel blends with rapeseed and with soybean has also been analyzed. The use of both antioxidants results in a considerable improvement in the oxidation stability of both types of biodiesel, especially using catechol. Adding catechol loads as low as 0.05% (m/m) in blends with soybean biodiesel and as low as 0.10% (m/m) in blends with rapeseed biodiesel is sufficient for the oxidation stabilities to comply with the restrictions established by the European EN14214 standard. An empirical linear equation is proposed to correlate the oxidation stability by the two methods, PetroOXY and Rancimat. It has been found that the presence of either catechol or 4-allyl-2,6-dimethoxyphenol as additives affects the correlation observed. PMID:25101258

  13. Oxidation stability of biodiesel fuels and blends using the Rancimat and PetroOXY methods. Effect of 4-allyl-2,6-dimethoxyphenol and catechol as biodiesel additives on oxidation stability.

    PubMed

    Botella, Lucía; Bimbela, Fernando; Martín, Lorena; Arauzo, Jesús; Sánchez, José L

    2014-01-01

    IN THE PRESENT WORK, SEVERAL FATTY ACID METHYL ESTERS (FAME) HAVE BEEN SYNTHESIZED FROM VARIOUS FATTY ACID FEEDSTOCKS: used frying olive oil, pork fat, soybean, rapeseed, sunflower, and coconut. The oxidation stabilities of the biodiesel samples and of several blends have been measured simultaneously by both the Rancimat method, accepted by EN14112 standard, and the PetroOXY method, prEN16091 standard, with the aim of finding a correlation between both methodologies. Other biodiesel properties such as composition, cold filter plugging point (CFPP), flash point (FP), and kinematic viscosity have also been analyzed using standard methods in order to further characterize the biodiesel produced. In addition, the effect on the biodiesel properties of using 4-allyl-2,6-dimethoxyphenol and catechol as additives in biodiesel blends with rapeseed and with soybean has also been analyzed. The use of both antioxidants results in a considerable improvement in the oxidation stability of both types of biodiesel, especially using catechol. Adding catechol loads as low as 0.05% (m/m) in blends with soybean biodiesel and as low as 0.10% (m/m) in blends with rapeseed biodiesel is sufficient for the oxidation stabilities to comply with the restrictions established by the European EN14214 standard. An empirical linear equation is proposed to correlate the oxidation stability by the two methods, PetroOXY and Rancimat. It has been found that the presence of either catechol or 4-allyl-2,6-dimethoxyphenol as additives affects the correlation observed. PMID:25101258

  14. Site-specific covalent modifications of human insulin by catechol estrogens: Reactivity and induced structural and functional changes

    NASA Astrophysics Data System (ADS)

    Ku, Ming-Chun; Fang, Chieh-Ming; Cheng, Juei-Tang; Liang, Huei-Chen; Wang, Tzu-Fan; Wu, Chih-Hsing; Chen, Chiao-Chen; Tai, Jung-Hsiang; Chen, Shu-Hui

    2016-06-01

    Proteins, covalently modified by catechol estrogens (CEs), were identified recently from the blood serum of diabetic patients and referred to as estrogenized proteins. Estrogenization of circulating insulin may occur and affect its molecular functioning. Here, the chemical reactivity of CEs towards specific amino acid residues of proteins and the structural and functional changes induced by the estrogenization of insulin were studied using cyclic voltammetry, liquid chromatography-mass spectrometry, circular dichroism spectroscopy, molecular modeling, and bioassays. Our results indicate that CEs, namely, 2- and 4-hydroxyl estrogens, were thermodynamically and kinetically more reactive than the catechol moiety. Upon co-incubation, intact insulin formed a substantial number of adducts with one or multiple CEs via covalent conjugation at its Cys 7 in the A or B chain, as well as at His10 or Lys29 in the B chain. Such conjugation was coupled with the cleavage of inter-chain disulfide linkages. Estrogenization on these sites may block the receptor-binding pockets of insulin. Insulin signaling and glucose uptake levels were lower in MCF-7 cells treated with modified insulin than in cells treated with native insulin. Taken together, our findings demonstrate that insulin molecules are susceptible to active estrogenization, and that such modification may alter the action of insulin.

  15. Site-specific covalent modifications of human insulin by catechol estrogens: Reactivity and induced structural and functional changes

    PubMed Central

    Ku, Ming-Chun; Fang, Chieh-Ming; Cheng, Juei-Tang; Liang, Huei-Chen; Wang, Tzu-Fan; Wu, Chih-Hsing; Chen, Chiao-Chen; Tai, Jung-Hsiang; Chen, Shu-Hui

    2016-01-01

    Proteins, covalently modified by catechol estrogens (CEs), were identified recently from the blood serum of diabetic patients and referred to as estrogenized proteins. Estrogenization of circulating insulin may occur and affect its molecular functioning. Here, the chemical reactivity of CEs towards specific amino acid residues of proteins and the structural and functional changes induced by the estrogenization of insulin were studied using cyclic voltammetry, liquid chromatography-mass spectrometry, circular dichroism spectroscopy, molecular modeling, and bioassays. Our results indicate that CEs, namely, 2- and 4-hydroxyl estrogens, were thermodynamically and kinetically more reactive than the catechol moiety. Upon co-incubation, intact insulin formed a substantial number of adducts with one or multiple CEs via covalent conjugation at its Cys 7 in the A or B chain, as well as at His10 or Lys29 in the B chain. Such conjugation was coupled with the cleavage of inter-chain disulfide linkages. Estrogenization on these sites may block the receptor-binding pockets of insulin. Insulin signaling and glucose uptake levels were lower in MCF-7 cells treated with modified insulin than in cells treated with native insulin. Taken together, our findings demonstrate that insulin molecules are susceptible to active estrogenization, and that such modification may alter the action of insulin. PMID:27353345

  16. DRIFTS studies on the role of surface water in stabilizing catechol-iron(III) complexes at the gas/solid interface.

    PubMed

    Tofan-Lazar, Julia; Situm, Arthur; Al-Abadleh, Hind A

    2013-10-10

    Surface water plays a crucial role in facilitating or inhibiting surface reactions in atmospheric aerosols. However, little is known about the role of surface water in the complexation of organic acid molecules to transition metals in multicomponent aerosol systems. We report herein results from real time DRIFTS experiments that show in situ complexation of catechol to Fe(III) under humid conditions. Catechol was schosen as a simple model for humic-like substances (HULIS) in aerosols and aged polyaromatic hydrocarbons (PAH). It was also detected in secondary organic aerosols (SOA) formed from the reaction of hydroxyl radicals with benzene. Given the importance of the iron content in aerosols and its biogeochemistry, our studies were conducted using FeCl3. For comparison, these surface-sensitive studies were complemented with bulk aqueous ATR-FTIR, UV-vis, and HPLC measurements for structural, quantitative, and qualitative information about complexes in the bulk, and potential degradation products in the dark. Under dry conditions, DRIFTS spectra show that gas phase catechol adsorbs molecularly and is fully protonated on samples containing FeCl3 with no evidence of complexation to Fe(III). Upon increasing the relative humidity to a value below the deliquescence of FeCl3, surface water facilitates ionic mobility resulting in the formation of monodentate catechol-Fe complexes. These complexes are stable at the gas/solid interface and do not undergo any further degradation in the dark as shown from bulk UV-vis and HPLC experiments. The implications of our studies on understanding interfacial and condensed phase chemistry relevant to multicomponent aerosols, water thin films on buildings, and ocean surfaces containing transition metals are discussed.

  17. BIOLOGICAL ADHESIVES. Adaptive synergy between catechol and lysine promotes wet adhesion by surface salt displacement.

    PubMed

    Maier, Greg P; Rapp, Michael V; Waite, J Herbert; Israelachvili, Jacob N; Butler, Alison

    2015-08-01

    In physiological fluids and seawater, adhesion of synthetic polymers to solid surfaces is severely limited by high salt, pH, and hydration, yet these conditions have not deterred the evolution of effective adhesion by mussels. Mussel foot proteins provide insights about adhesive adaptations: Notably, the abundance and proximity of catecholic Dopa (3,4-dihydroxyphenylalanine) and lysine residues hint at a synergistic interplay in adhesion. Certain siderophores—bacterial iron chelators—consist of paired catechol and lysine functionalities, thereby providing a convenient experimental platform to explore molecular synergies in bioadhesion. These siderophores and synthetic analogs exhibit robust adhesion energies (E(ad) ≥-15 millijoules per square meter) to mica in saline pH 3.5 to 7.5 and resist oxidation. The adjacent catechol-lysine placement provides a "one-two punch," whereby lysine evicts hydrated cations from the mineral surface, allowing catechol binding to underlying oxides. PMID:26250681

  18. Specificity of catechol ortho-cleavage during para-toluate degradation by Rhodococcus opacus 1cp.

    PubMed

    Suvorova, M M; Solianikova, I P; Golovleva, L A

    2006-12-01

    Degradation of para-toluate by Rhodococcus opacus 1cp was investigated. Activities of the key enzymes of this process, catechol 1,2-dioxygenase and muconate cycloisomerase, are detected in this microorganism. Growth on p-toluate was accompanied by induction of two catechol 1,2-dioxygenases. The substrate specificity and physicochemical properties of one enzyme are identical to those of chlorocatechol 1,2-dioxygenase; induction of the latter enzyme was observed during R. opacus 1cp growth on 4-chlorophenol. The other enzyme isolated from the biomass grown on p-toluate exhibited lower rate of chlorinated substrate cleavage compared to the catechol substrate. However, this enzyme is not identical to the catechol 1,2-dioxygenase cloned in this strain within the benzoate catabolism operon. This supports the hypothesis on the existence of multiple forms of dioxygenases as adaptive reactions of microorganisms in response to environmental stress.

  19. H-point curve isolation method for determination of catechol in complex unknown mixtures

    NASA Astrophysics Data System (ADS)

    Hasani, Masoumeh; Mohammadi, Masoumeh; Shariati-Rad, Masoud; Abdollahi, Hamid

    2012-10-01

    In this work, the combination of H-point curve isolation method (HPCIM) and H-point standard additions method (HPSAM) was used for determination of catechol in the presence of phenolic interferents. Spectrophotometric multivariate calibration data constructed by successive standard additions of an analyte in an unknown matrix was used by the method. A cumulative spectrum for interferents in sample was extracted by HPCIM and then HPSAM is used for determination of the catechol concentration by obtained cumulative interferents spectrum. The method was tested with simulated data set. The spectrum obtained from applying HPCIM to the simulated data well agrees with the cumulative spectra of the interferents. The method was applied to the determination of catechol in the presence of highly overlapping interferents in synthetic ternary mixtures using spectrophotometric data. Moreover, the proposed method was successfully used for determination of catechol in real complicated matrices of tea and urine samples. Percent recoveries were between 95.4 and 113.6.

  20. BIOLOGICAL ADHESIVES. Adaptive synergy between catechol and lysine promotes wet adhesion by surface salt displacement.

    PubMed

    Maier, Greg P; Rapp, Michael V; Waite, J Herbert; Israelachvili, Jacob N; Butler, Alison

    2015-08-01

    In physiological fluids and seawater, adhesion of synthetic polymers to solid surfaces is severely limited by high salt, pH, and hydration, yet these conditions have not deterred the evolution of effective adhesion by mussels. Mussel foot proteins provide insights about adhesive adaptations: Notably, the abundance and proximity of catecholic Dopa (3,4-dihydroxyphenylalanine) and lysine residues hint at a synergistic interplay in adhesion. Certain siderophores—bacterial iron chelators—consist of paired catechol and lysine functionalities, thereby providing a convenient experimental platform to explore molecular synergies in bioadhesion. These siderophores and synthetic analogs exhibit robust adhesion energies (E(ad) ≥-15 millijoules per square meter) to mica in saline pH 3.5 to 7.5 and resist oxidation. The adjacent catechol-lysine placement provides a "one-two punch," whereby lysine evicts hydrated cations from the mineral surface, allowing catechol binding to underlying oxides.

  1. Protein-responsive assemblies from catechol-metal ion supramolecular coordination.

    PubMed

    Yuan, C; Chen, J; Yu, S; Chang, Y; Mao, J; Xu, Y; Luo, W; Zeng, B; Dai, L

    2015-03-21

    Supramolecular self-assembly driven by catechol-metal ion coordination has gained great success in the fabrication of functional materials including adhesives, capsules, coatings and hydrogels. However, this route has encountered a great challenge in the construction of nanoarchitectures in the absence of removable templates, because of the uncontrollable crosslinking of catechol-metal ion coordination. Herein, we show that a supramolecular approach, combining both catechol-metal ion coordination and polymer self-assembly together, can organize polymers into hybrid nanoassemblies ranging from solid particles, homogeneous vesicles to Janus vesicles. Without the introduction of a specific binding ligand or complicated molecular design, these assemblies can totally disassemble in response to proteins. UV/vis absorption, fluorescence quenching and recovery investigations have confirmed that proteins can seize metal ions from the hybrid nanoassemblies, thus causing the degradation of catechol-metal ion coordination networks.

  2. Catechol oxidase activity of di-Cu2+-substituted aminopeptidase from Streptomyces griseus.

    PubMed

    da Silva, Giordano F Z; Ming, Li-June

    2005-11-30

    Streptomyces griseus aminopeptidase exhibits activities toward the hydrolyses of peptides and bis(p-nitrophenyl)phosphate (40 billion fold) and catechol oxidation reported herein with catalytic efficiency (kcat/Km) only about 10 times smaller than that of gypsywort catechol oxidase. The multifunctionality of this enzyme suggests that it is a unique system for further exploration of protein structure and function and a template for design of enzymes of diverse activities. PMID:16305209

  3. Characterization of catechol derivative removal by lignin peroxidase in aqueous mixture.

    PubMed

    Cohen, Shaul; Belinky, Paula A; Hadar, Yitzhak; Dosoretz, Carlos G

    2009-04-01

    The use of lignin peroxidase (LIP) as an alternative method for the removal of four catechols (1,2-dihydroxybenzene): catechol (CAT), 4-chlorocatechol (4-CC), 4,5-dichlorocatechol (4,5-DCC) and 4-methylcatechol (4-MC) typical pollutants in wastewater derived from oil and paper industries, was evaluated. The removal of 2mM catecholic substrates by 1 microM LIP after 1h was in the following order: 4,5-DCC (95%)>4-CC(90%)>CAT(55%)>4-MC(43%). Except for 4-MC, all reactions were accompanied by the formation of insoluble products, leading to LIP precipitation. LIP was exposed to soluble or insoluble product-dependent inactivation, depending on the substrates tested, immediately at the start of the reactions. Despite immediate enzyme inactivation, removal of catecholic substrates continued, resulting in oligomeric product formation. Major oxidation products analyzed were compatible with dimeric, trimeric and tetrameric structures. Ether linkages and a benzoquinone structure were detected in two purified oligochlorocatechols. Catechol derivatives removal initiated by LIP, seems to be different for each catecholic substrate in terms of substrate consumption and transformation, and of enzyme activity.

  4. Synthesis, Characterization, and Preliminary Investigation of Cell Interaction of Magnetic Nanoparticles with Catechol-Containing Shells

    SciTech Connect

    Wagner, Kerstin; Seemann, Thomas; Wyrwa, Ralf; Schnabelrauch, Matthias; Clement, Joachim H.; Mueller, Robert; Nietzsche, Sandor

    2010-12-02

    Superparamagnetic iron oxide cores were synthesized by co-precipitation of Fe(II) and Fe(III) salts and subsequently stabilized by coating with different catechols (levodopa, dopamine, hydrocaffeic acid, dopamine-containing carboxymethyl dextran) known to act as high-affinity, bidentate ligands for Fe(III). The prepared stable magnetic fluids were characterized with regard to their chemical composition (content of iron and shell material, Fe(II)/Fe(III) ratio) and their physical properties (size, surface charge, magnetic parameters). The nanoparticles showed no or only slight cytotoxic effects within 1 and 4 days of incubation with 3T3 fibroblast cells. Preliminary experiments were performed to study the interaction of the prepared nanoparticles with human MCF-7 breast cancer cells and leukocytes. An intense interaction of the MCF-7 cells with these particles was found whereas the leukocytes showed a lower tendency of interaction. Based on these finding, the novel magnetic nanoparticles possess the potential for use in depletion of tumor cells from peripheral blood.

  5. Synthesis, Characterization, and Preliminary Investigation of Cell Interaction of Magnetic Nanoparticles with Catechol-Containing Shells

    NASA Astrophysics Data System (ADS)

    Wagner, Kerstin; Seemann, Thomas; Wyrwa, Ralf; Clement, Joachim H.; Müller, Robert; Nietzsche, Sandor; Schnabelrauch, Matthias

    2010-12-01

    Superparamagnetic iron oxide cores were synthesized by co-precipitation of Fe(II) and Fe(III) salts and subsequently stabilized by coating with different catechols (levodopa, dopamine, hydrocaffeic acid, dopamine-containing carboxymethyl dextran) known to act as high-affinity, bidentate ligands for Fe(III). The prepared stable magnetic fluids were characterized with regard to their chemical composition (content of iron and shell material, Fe(II)/Fe(III) ratio) and their physical properties (size, surface charge, magnetic parameters). The nanoparticles showed no or only slight cytotoxic effects within 1 and 4 days of incubation with 3T3 fibroblast cells. Preliminary experiments were performed to study the interaction of the prepared nanoparticles with human MCF-7 breast cancer cells and leukocytes. An intense interaction of the MCF-7 cells with these particles was found whereas the leukocytes showed a lower tendency of interaction. Based on these finding, the novel magnetic nanoparticles possess the potential for use in depletion of tumor cells from peripheral blood.

  6. A Novel Mechanism for Adenylyl Cyclase Inhibition from the Crystal Structure of its Complex with Catechol Estrogen

    SciTech Connect

    Steegborn,C.; Litvin, T.; Hess, K.; Capper, A.; Taussig, R.; Buck, J.; Levin, L.; Wu, H.

    2005-01-01

    Catechol estrogens are steroid metabolites that elicit physiological responses through binding to a variety of cellular targets. We show here that catechol estrogens directly inhibit soluble adenylyl cyclases and the abundant trans-membrane adenylyl cyclases. Catechol estrogen inhibition is non-competitive with respect to the substrate ATP, and we solved the crystal structure of a catechol estrogen bound to a soluble adenylyl cyclase from Spirulina platensis in complex with a substrate analog. The catechol estrogen is bound to a newly identified, conserved hydrophobic patch near the active center but distinct from the ATP-binding cleft. Inhibitor binding leads to a chelating interaction between the catechol estrogen hydroxyl groups and the catalytic magnesium ion, distorting the active site and trapping the enzyme substrate complex in a non-productive conformation. This novel inhibition mechanism likely applies to other adenylyl cyclase inhibitors, and the identified ligand-binding site has important implications for the development of specific adenylyl cyclase inhibitors.

  7. Structural and spectroscopic studies of a model for catechol oxidase.

    PubMed

    Smith, Sarah J; Noble, Christopher J; Palmer, Randahl C; Hanson, Graeme R; Schenk, Gerhard; Gahan, Lawrence R; Riley, Mark J

    2008-05-01

    A binuclear copper complex, [Cu2(BPMP) (OAc)2][ClO4] x H2O, has been prepared using the binucleating ligand 2,6-bis[bis(pyridin-2-ylmethylamino)methyl]-4-methylphenol (H-BPMP). The X-ray crystal structure reveals the copper centers to have a five-coordinate square pyramidal geometry, with the acetate ligands bound terminally. The bridging phenolate occupies the apical position of the square-based pyramids and magnetic susceptibility, electron paramagnetic resonance (EPR) and variable-temperature variable-field magnetic circular dichroism (MCD) measurements indicate that the two centers are very weakly antiferromagnetically coupled (J = -0.6 cm(-1)). Simulation of the dipole-dipole-coupled EPR spectrum showed that in solution the Cu-O-Cu angle was increased from 126 degrees to 160 degrees and that the internuclear distance was larger than that observed crystallographically. The high-resolution spectroscopic information obtained has been correlated with a detailed ligand-field analysis to gain insight into the electronic structure of the complex. Symmetry arguments have been used to demonstrate that the sign of the MCD is characteristic of the tetragonally elongated environment. The complex also displays catecholase activity (k(cat) = 15 +/- 1.5 min(-1), K(M) = 6.4 +/- 1.8 mM), which is compared with other dicopper catechol oxidase models. PMID:18188615

  8. Radicals from the gas-phase pyrolysis of catechol: 1. o-Semiquinone and ipso-catechol radicals.

    PubMed

    Khachatryan, Lavrent; Adounkpe, Julien; Asatryan, Rubik; Dellinger, Barry

    2010-02-18

    The formation of environmentally persistent free radicals (EPFRs) from the gas-phase pyrolysis of catechol (CT) was studied over a temperature range of 400-750 degrees C using the technique of low-temperature matrix isolation electron paramagnetic resonance (LTMI-EPR) spectroscopy. A split singlet EPR spectrum with a g value of 2.0052 was observed. To aid in the interpretation of this spectrum, a detailed analysis of the potential energy surface of CT decomposition pathways was performed employing CBS-QB3 multilevel and DFT individual methods. The energetically favored channels were the formation of ipso- and alpha-CT isomers of CT as well as o-semiquinone (o-SQ) radicals from ipso- and alpha-CT. ipso-CT as well as open ipso-CT radicals were apparently unstable intermediates that could not be accumulated in sufficiently high concentrations to be detected by EPR. The calculated EPR spectrum of o-SQ radical is consistent with the formation of an oxygen-centered radical with a high g value observed experimentally. The hyperfine splitting of the observed spectrum can be attributed to the formation of hydrogen bonds in radical dimers. The lack of experimental observation of o-benzoquinone, an anticipated pyrolysis product, has been explained based on theoretical calculations.

  9. Influence of chemical kinetics on postcolumn reaction in a capillary Taylor reactor with catechol analytes and photoluminescence following electron transfer.

    PubMed

    Jung, Moon Chul; Weber, Stephen G

    2005-02-15

    Postcolumn derivatization reactions can enhance detector sensitivity and selectivity, but their successful combination with capillary liquid chromatography has been limited because of the small peak volumes in capillary chromatography. A capillary Taylor reactor (CTR), developed in our laboratory, provides simple and effective mixing and reaction in a 25-microm-radius postcolumn capillary. Homogenization of reactant streams occurs by radial diffusion, and a chemical reaction follows. Three characteristic times for a given reaction process can be predicted using simple physical and chemical parameters. Two of these times are the homogenization time, which governs how long it takes the molecules in the analyte and reagent streams to mix, and the reaction time, which governs how long the molecules in a homogeneous solution take to react. The third characteristic time is an adjustment to the reaction time called the start time, which represents an estimate of the average time the analyte stream spends without exposure to reagent. In this study, laser-induced fluorescence monitored the extent of the postcolumn reaction (reduction of Os(bpy)3(3+) by analyte to the photoluminescent Os(bpy)3(2+)) in a CTR. The reaction time depends on the reaction rates. Analysis of product versus time data yielded second-order reaction rate constants between the PFET reagent, tris(2,2'-bipyridine)osmium, and standards ((ferrocenylmethyl)trimethylammonium cation and p-hydroquinone) or catechols (dopamine, epinephrine, norepinephrine, 3, 4-dihydroxyphenylacetic acid. The extent of the reactions in a CTR were then predicted from initial reaction conditions and compared to experimental results. Both the theory and experimental results suggested the reactions of catechols were generally kinetically controlled, while those of the standards were controlled by mixing time (1-2 s). Thus, the extent of homogenization can be monitored in a CTR using the relatively fast reaction of the reagent and p

  10. Comparative modeling of the latent form of a plant catechol oxidase using a molluskan hemocyanin structure.

    PubMed

    Gerdemann, Carsten; Eicken, Christoph; Galla, Hans Joachim; Krebs, Bernt

    2002-04-10

    The structure of the precursor form of catechol oxidase from sweet potatoes (Ipomoea batatas) has been modeled on the basis of the 3D structural data of mature catechol oxidase [Nat. Struct. Biol. 5 (1998) 1084] and of hemocyanin from giant octopus (Octopus dofleini) [J. Mol. Biol. 278 (1998) 855]. A C-terminal extension peptide is found in the cDNA sequence but not in the purified, mature form of catechol oxidase. Superimposition of the 3D structures of the native hemocyanin and catechol oxidase reveals a close relationship except for an additional C-terminal domain only found in the hemocyanin structure. As sequence alignment shows good homology this domain of the hemocyanin structure was used as a template to model the 3D structure of the C-terminal extension peptide of catechol oxidase. As hemocyanins show no or only weak catecholase activity due to this domain this indicates an inhibitory function of this extension peptide. Beside this possible shielding function for the precursor form, evidence for a function in copper-uptake also increases due to the location of three histidine residues in the model. PMID:11931976

  11. Relation Between the Adsorbed Quantity and the Immersion Enthalpy in Catechol Aqueous Solutions on Activated Carbons

    PubMed Central

    Moreno-Piraján, Juan Carlos; Blanco, Diego; Giraldo, Liliana

    2012-01-01

    An activated carbon, CarbochemTM—PS230, was modified by chemical and thermal treatment in flow of H2, in order to evaluate the influence of the activated carbon chemical characteristics in the adsorption of the catechol. The catechol adsorption in aqueous solution was studied along with the effect of the pH solution in the adsorption process of modified activated carbons and the variation of immersion enthalpy of activated carbons in the aqueous solutions of catechol. The interaction solid-solution is characterized by adsorption isotherms analysis, at 298 K and pH 7, 9 and 11 in order to evaluate the adsorption value above and below that of the catechol pKa. The adsorption capacity of carbons increases when the solution pH decreases. The retained amount increases slightly in the reduced carbon to maximum adsorption pH and diminishes in the oxidized carbon. Similar conclusions are obtained from the immersion enthalpies, whose values increase with the solute quantity retained. In granular activated carbon (CAG), the immersion enthalpies obtained are between 21.5 and 45.7 J·g−1 for catechol aqueous solutions in a range of 20 at 1500 mg·L−1. PMID:22312237

  12. Surface Complexation at the TiO(2) (anatase)/Aqueous Solution Interface: Chemisorption of Catechol.

    PubMed

    Rodríguez; Blesa; Regazzoni

    1996-01-15

    Catechol adsorbs at the TiO(2) (anatase)/aqueous solution interface forming inner-sphere surface complexes. The UV-visible differential reflectance spectrum of surface titanium-catecholate complexes presents a band centered at 420 nm which corresponds to the ligand to metal charge transfer transition within the surface complexes. At pH values below pK(a1), the surface excess of catechol is almost insensitive toward pH and presents a Langmuirian dependence with the concentration of uncomplexed catechol. The ratio Gamma(max):N(S) (N(S) being the measured density of available OH surface groups) indicates a prevailing 1 to 2 ligand exchange adsorption stoichiometry. In the range pH >/= pK(a1), the catechol surface excess decreases markedly with increasing pH. Formation of 1 to 1 surface complexes produces an excess of negative surface charge that is revealed by the shift of the iep to lower pH values. The reported data, which are supplemented with information on the charging behavior of TiO(2) suspended in indifferent electrolyte solutions, are interpreted in terms of the multi-site surface complexation model. In this model, two types of surface OH groups are considered: identical withTiOH(1/3-) and identical withOH(1/3+). Although both surface groups undergo protonation-deprotonation reactions, only identical withTiOH(1/3-) are prone to chemisorption.

  13. Synthetic models of the active site of catechol oxidase: mechanistic studies.

    PubMed

    Koval, Iryna A; Gamez, Patrick; Belle, Catherine; Selmeczi, Katalin; Reedijk, Jan

    2006-09-01

    The ability of copper proteins to process dioxygen at ambient conditions has inspired numerous research groups to study their structural, spectroscopic and catalytic properties. Catechol oxidase is a type-3 copper enzyme usually encountered in plant tissues and in some insects and crustaceans. It catalyzes the conversion of a large number of catechols into the respective o-benzoquinones, which subsequently auto-polymerize, resulting in the formation of melanin, a dark pigment thought to protect a damaged tissue from pathogens. After the report of the X-ray crystal structure of catechol oxidase a few years earlier, a large number of publications devoted to the biomimetic modeling of its active site appeared in the literature. This critical review (citing 114 references) extensively discusses the synthetic models of this enzyme, with a particular emphasis on the different approaches used in the literature to study the mechanism of the catalytic oxidation of the substrate (catechol) by these compounds. These are the studies on the substrate binding to the model complexes, the structure-activity relationship, the kinetic studies of the catalytic oxidation of the substrate and finally the substrate interaction with (per)oxo-dicopper adducts. The general overview of the recognized types of copper proteins and the detailed description of the crystal structure of catechol oxidase, as well as the proposed mechanisms of the enzymatic cycle are also presented. PMID:16936929

  14. Simultaneous determination of hydroquinone and catechol at gold nanoparticles mesoporous silica modified carbon paste electrode.

    PubMed

    Tashkhourian, J; Daneshi, M; Nami-Ana, F; Behbahani, M; Bagheri, A

    2016-11-15

    A new electrochemical sensor based on gold nanoparticles mesoporous silica modified carbon paste electrode (AuNPs-MPS) was developed for simultaneous determination of hydroquinone and catechol. Morphology and structure of the AuNPs-MPS were characterized by transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The electrochemical behavior of hydroquinone and catechol were investigated using square wave voltammetry and the results indicate that the electrochemical responses are improved significantly at the modified electrode. The observed oxidative peaks separation of about 120mV made possible the simultaneous determination of hydroquinone and catechol in their binary-mixture. Under the optimized condition, a linear dynamic range of 10.0μM-1.0mM range for hydroquinone with the detection limit of 1.2μM and from 30.0μM-1.0mM for catechol with the detection limit of 1.1μM were obtained. The applicability of the method was demonstrated by the recovery studies of hydroquinone and catechol in spiked tap water samples. PMID:27420383

  15. Comparative modeling of the latent form of a plant catechol oxidase using a molluskan hemocyanin structure.

    PubMed

    Gerdemann, Carsten; Eicken, Christoph; Galla, Hans Joachim; Krebs, Bernt

    2002-04-10

    The structure of the precursor form of catechol oxidase from sweet potatoes (Ipomoea batatas) has been modeled on the basis of the 3D structural data of mature catechol oxidase [Nat. Struct. Biol. 5 (1998) 1084] and of hemocyanin from giant octopus (Octopus dofleini) [J. Mol. Biol. 278 (1998) 855]. A C-terminal extension peptide is found in the cDNA sequence but not in the purified, mature form of catechol oxidase. Superimposition of the 3D structures of the native hemocyanin and catechol oxidase reveals a close relationship except for an additional C-terminal domain only found in the hemocyanin structure. As sequence alignment shows good homology this domain of the hemocyanin structure was used as a template to model the 3D structure of the C-terminal extension peptide of catechol oxidase. As hemocyanins show no or only weak catecholase activity due to this domain this indicates an inhibitory function of this extension peptide. Beside this possible shielding function for the precursor form, evidence for a function in copper-uptake also increases due to the location of three histidine residues in the model.

  16. Ortho-substituted catechol derivatives: the effect of intramolecular hydrogen-bonding pathways on chloride anion recognition.

    PubMed

    Winstanley, Keith J; Smith, David K

    2007-04-13

    This paper reports a series of chloride anion receptors containing two catechol head groups connected through their ortho-positions via a spacer chain. The linking group chosen to attach the spacer chain to the catechol units has a major impact on the anion-binding potential of the receptor. Linking groups that are capable of forming stable six-membered intramolecular hydrogen-bonded rings with the catechol O-H groups significantly inhibit the ability of the catechol units to hydrogen bond to chloride anions. However, where the linking groups are only capable of forming five- or seven-membered intramolecular hydrogen-bonded rings, then anion binding via hydrogen bonding through the catechol O-H groups becomes a possibility. This process is solvent dependent; the presence of competitive solvent (e.g., DMSO-d6) disrupts the intramolecular hydrogen-bonding pattern and enhances anion binding relative to simple unfunctionalized catechol. The most effective receptor is that in which the hydrogen-bonding linker (-CH2CONH-) is most distant from the catechol units and can only form a seven-membered intramolecular hydrogen-bonded ring. In this case, the receptor, which contains two catechol units, is a more effective chloride anion binder than simple unfunctionalized catechol, demonstrating that the two head groups, in combination with the N-H groups in the linker, act cooperatively and enhance the degree of anion binding. In summary, this paper provides insight into the hydrogen-bonding patterns in ortho-functionalized catechols and the impact these have on the potential of the catechol O-H groups to hydrogen bond to a chloride anion.

  17. Catechol-O-methyltransferase association with hemoglobin A1c

    PubMed Central

    Hall, Kathryn T.; Jablonski, Kathleen A.; Chen, Ling; Harden, Maegan; Tolkin, Benjamin R.; Kaptchuk, Ted J.; Bray, George A.; Ridker, Paul M.; Florez, Jose C.; Chasman, Daniel I.

    2016-01-01

    Aims Catecholamines have metabolic effects on blood pressure, insulin sensitivity and blood glucose. Genetic variation in catechol-O-methyltransferase (COMT), an enzyme that degrades catecholamines, is associated with cardiometabolic risk factors and incident cardiovascular disease (CVD). Here we examined COMT effects on glycemic function and type 2 diabetes. Methods We tested whether COMT polymorphisms were associated with baseline HbA1c in the Women’s Genome Health Study (WGHS), and Meta-Analyses of Glucose and Insulin-related traits Consortium (MAGIC), and with susceptibility to type 2 diabetes in WGHS, DIAbetes Genetics Replication And Meta-analysis consortium (DIAGRAM), and the Diabetes Prevention Program (DPP). Given evidence that COMT modifies some drug responses, we examined association with type 2 diabetes and randomized metformin and aspirin treatment. Results COMT rs4680 high-activity G-allele was associated with lower HbA1c in WGHS (β = −0.032% [0.012], p = 0.008) and borderline significant in MAGIC (β = −0.006% [0.003], p = 0.07). Combined COMT per val allele effects on type 2 diabetes were significant (OR = 0.98 [0.96–0.998], p = 0.03) in fixed-effects analyses across WGHS, DIAGRAM, and DPP. Similar results were obtained for 2 other COMT SNPs rs4818 and rs4633. In the DPP, the rs4680 val allele was borderline associated with lower diabetes incidence among participants randomized to metformin (HR = 0.81 [0.65–1.00], p = 0.05). Conclusions COMT rs4680 high-activity G-allele was associated with lower HbA1c and modest protection from type 2 diabetes. The directionality of COMT associations was concordant with those previously observed for cardiometabolic risk factors and CVD. PMID:27282867

  18. A Hyperactive Cobalt-Substituted Extradiol-Cleaving Catechol Dioxygenase

    PubMed Central

    Fielding, Andrew J.; Farquhar, Erik R.

    2011-01-01

    Homoprotocatechuate (HPCA) 2,3-dioxygenase from Brevibacterium fuscum (Fe-HPCD) has an Fe(II) center in its active site that can be replaced with Mn(II) or Co(II). While Mn-HPCD exhibits steady state kinetic parameters comparable to those of Fe-HPCD, Co-HPCD behaves somewhat differently exhibiting a significantly higher KMO2 and kcat. The high activity of Co-HPCD is surprising, given that cobalt has the highest standard M(III/II) redox potential of the three metals. Comparison of the X-ray crystal structures of the resting and substrate-bound forms of Fe-, Mn-, and Co-HPCD shows that metal-substitution has no effect on the local ligand environment, the conformational integrity of the active site, or the overall protein structure, suggesting that the protein structure does not differentially tune the potential of the metal center. Analysis of the steady state kinetics of Co-HPCD suggests that the Co(II) center alters the relative rate constants for the interconversion of intermediates in the catalytic cycle but still allows the dioxygenase reaction to proceed efficiently. When compared with the kinetic data for Fe- and Mn-HPCD, these results show that dioxygenase catalysis can proceed at high rates over a wide range of metal redox potentials. This is consistent with the proposed mechanism in which the metal mediates electron transfer between the catechol substrate and O2 to form the postulated [M(II)(semiquinone)superoxo] reactive species. These kinetic differences and the spectroscopic properties of Co-HPCD provide new tools with which to explore the unique O2 activation mechanism associated with the extradiol dioxygenase family. PMID:21153851

  19. 4-nitrocatechol as a probe of a Mn(II)-dependent extradiol-cleaving catechol dioxygenase (MndD): comparison with relevant Fe(II) and Mn(II) model complexes.

    PubMed

    Reynolds, Mark F; Costas, Miquel; Ito, Masami; Jo, Du-Hwan; Tipton, A Alex; Whiting, Adam K; Que, Lawrence

    2003-02-01

    Mn(II)-dependent 3,4-dihydroxyphenylacetate 2,3-dioxygenase (MndD) is an extradiol-cleaving catechol dioxygenase from Arthrobacter globiformis that has 82% sequence identity to and cleaves the same substrate (3,4-dihydroxyphenylacetic acid) as Fe(II)-dependent 3,4-dihydroxyphenylacetate 2,3-dioxygenase (HPCD) from Brevibacterium fuscum. We have observed that MndD binds the chromophoric 4-nitrocatechol (4-NCH(2)) substrate as a dianion and cleaves it extremely slowly, in contrast to the Fe(II)-dependent enzymes which bind 4-NCH(2) mostly as a monoanion and cleave 4-NCH(2) 4-5 orders of magnitude faster. These results suggest that the monoanionic binding state of 4-NC is essential for extradiol cleavage. In order to address the differences in 4-NCH(2) binding to these enzymes, we synthesized and characterized the first mononuclear monoanionic and dianionic Mn(II)-(4-NC) model complexes as well as their Fe(II)-(4-NC) analogs. The structures of [(6-Me(2)-bpmcn)Fe(II)(4-NCH)](+), [(6-Me(3)-TPA)Mn(II)(DBCH)](+), and [(6-Me(2)-bpmcn)Mn(II)(4-NCH)](+) reveal that the monoanionic catecholate is bound in an asymmetric fashion (Delta r(metal-O(catecholate))=0.25-0.35 A), as found in the crystal structures of the E(.)S complexes of extradiol-cleaving catechol dioxygenases. Acid-base titrations of [(L)M(II)(4-NCH)](+) complexes in aprotic solvents show that the p K(a) of the second catecholate proton of 4-NCH bound to the metal center is half a p K(a) unit higher for the Mn(II) complexes than for the Fe(II) complexes. These results are in line with the Lewis acidities of the two divalent metal ions but are the opposite of the trend observed for 4-NCH(2) binding to the Mn(II)- and Fe(II)-catechol dioxygenases. These results suggest that the MndD active site decreases the second p K(a) of the bound 4-NCH(2) relative to the HPCD active site.

  20. Bioelectrocatalytic properties of lignin peroxidase from Phanerochaete chrysosporium in reactions with phenols, catechols and lignin-model compounds.

    PubMed

    Ferapontova, Elena E; Castillo, John; Gorton, Lo

    2006-09-01

    Bioelectrocatalytic reduction of H(2)O(2) catalysed by lignin peroxidase from Phanerochaete chrysosporium (LiP) was studied with LiP-modified graphite electrodes to elucidate the ability of LiP to electro-enzymatically oxidise phenols, catechols, as well as veratryl alcohol (VA) and some other high-redox-potential lignin model compounds (LMC). Flow-through amperometric experiments performed at +0.1 V vs. Ag|AgCl demonstrated that LiP displayed significant bioelectrocatalytic activity for the reduction of H(2)O(2) both directly (i.e., in direct electron transfer (ET) reaction between LiP and the electrode) and using most of studied compounds acting as redox mediators in the LiP bioelectrocatalytic cycle, with a pH optimum of 3.0. The bioelectrocatalytic reduction of H(2)O(2) mediated by VA and effects of VA on the efficiency of bioelectrocatalytic oxidation of other co-substrates acting as mediators were investigated. The bioelectrocatalytic oxidation of phenol- and catechol derivatives and 2,2'-azino-bis(3-ethyl-benzothiazoline-6-sulphonate) by LiP was independent of the presence of VA, whereas the efficiency of the LiP bioelectrocatalysis with the majority of other LMC acting as mediators increased upon addition of VA. Special cases were phenol and 4-methoxymandelic acid (4-MMA). Both phenol and 4-MMA suppressed the bioelectrocatalytic activity of LiP below the direct ET level, which was, however, restored and increased in the presence of VA mediating the ET between LiP and these two compounds. The obtained results suggest different mechanisms for the bioelectrocatalysis of LiP depending on the chemical nature of the mediators and are of a special interest both for fundamental science and for application of LiP in biotechnological processes as solid-phase bio(electro)catalyst for decomposition/detection of recalcitrant aromatic compounds.

  1. Purification and spectroscopic studies on catechol oxidase from lemon balm (Melissa officinalis).

    PubMed

    Rompel, Annette; Büldt-Karentzopoulos, Klaudia; Molitor, Christian; Krebs, Bernt

    2012-09-01

    A catechol oxidase from lemon balm (Melissa officinalis) moCO which only catalyzes the oxidation of catechols to quinones without hydroxylating tyrosine was purified. The molecular mass of the M. officinalis enzyme of 39,370 Da was obtained by MALDI mass spectrometry and the isoelectric point was determined to be 3.4. Addition of 2 eq. H(2)O(2) to the enzyme leads to oxy catechol oxidase. In the UV/Vis spectrum two new absorption bands occur at 343 nm (ε=8510 M(-1)cm(-1)) and 580 nm (ε=580 M(-1)cm(-1)) due to O(2)(2-)Cu (II) charge transfer transitions in accordance with the oxy forms of other type 3 copper proteins. The N-terminal sequence has been determined by Edman degradation to NPVQAPELDKCGTAT, exhibiting a proline at the second and sixth position conserved in other polyphenol oxidases. PMID:22727580

  2. Effect of β-cyclodextrin on intra and intermolecular Michael addition of some catechol derivatives.

    PubMed

    Khalafi, Lida; Rafiee, Mohammad; Fathi, Sahar

    2014-01-24

    The oxidation reactions of catechol, dopamine and epinephrine have been studied in the absence and presence of N-methylaniline by UV-Vis. Spectrophotometry. A variety of reaction pathways (inter and intramolecular reactions) that followed by this oxidation have been observed depending on the nature of catechol derivatives. The observed homogeneous rate constants of the reactions were estimated by fitting the absorption time profiles for each reaction. The effect of β-cyclodextrin and its inclusion complex has also been studied on the chosen reactions. The formation constants of the complexes of catechol, dopamine and epinephrine with β-cyclodextrin as well as the rate constants of the reactions of free and complexed forms have been obtained by fitting the absorption-time spectra to a proposed kinetic-equilibrium model.

  3. Catechols as Sources of Hydrogen Atoms in Radical Deiodination and Related Reactions.

    PubMed

    Povie, Guillaume; Ford, Leigh; Pozzi, Davide; Soulard, Valentin; Villa, Giorgio; Renaud, Philippe

    2016-09-01

    When used with trialkylboranes, catechol derivatives, which are low-cost and low toxicity, are valuable hydrogen atom donors for radical chain reactions involving alkyl iodides and related radical precursors. The system 4-tert-butylcatechol/triethylborane has been used to reduce a series of secondary and tertiary iodides, a xanthate, and a thiohydroxamate ester. Catechol derivatives are right in the optimal kinetic window for synthetic applications, as demonstrated by highly efficient radical cyclizations. Cyclizations leading to the formation of quaternary centers can be performed in an all-at-once process (no slow addition of the hydrogen atom donor) at standard concentrations. The H-donor properties of catechol derivatives can be fine-tuned by changing their substitution pattern. In slow radical cyclization processes, an enhanced ratio of cyclized/uncyclized products was obtained by using 3-methoxycatechol instead of 4-tert-butylcatechol.

  4. Effect of β-cyclodextrin on intra and intermolecular Michael addition of some catechol derivatives

    NASA Astrophysics Data System (ADS)

    Khalafi, Lida; Rafiee, Mohammad; Fathi, Sahar

    2014-01-01

    The oxidation reactions of catechol, dopamine and epinephrine have been studied in the absence and presence of N-methylaniline by UV-Vis. Spectrophotometry. A variety of reaction pathways (inter and intramolecular reactions) that followed by this oxidation have been observed depending on the nature of catechol derivatives. The observed homogeneous rate constants of the reactions were estimated by fitting the absorption time profiles for each reaction. The effect of β-cyclodextrin and its inclusion complex has also been studied on the chosen reactions. The formation constants of the complexes of catechol, dopamine and epinephrine with β-cyclodextrin as well as the rate constants of the reactions of free and complexed forms have been obtained by fitting the absorption-time spectra to a proposed kinetic-equilibrium model.

  5. Purification and spectroscopic studies on catechol oxidase from lemon balm (Melissa officinalis).

    PubMed

    Rompel, Annette; Büldt-Karentzopoulos, Klaudia; Molitor, Christian; Krebs, Bernt

    2012-09-01

    A catechol oxidase from lemon balm (Melissa officinalis) moCO which only catalyzes the oxidation of catechols to quinones without hydroxylating tyrosine was purified. The molecular mass of the M. officinalis enzyme of 39,370 Da was obtained by MALDI mass spectrometry and the isoelectric point was determined to be 3.4. Addition of 2 eq. H(2)O(2) to the enzyme leads to oxy catechol oxidase. In the UV/Vis spectrum two new absorption bands occur at 343 nm (ε=8510 M(-1)cm(-1)) and 580 nm (ε=580 M(-1)cm(-1)) due to O(2)(2-)Cu (II) charge transfer transitions in accordance with the oxy forms of other type 3 copper proteins. The N-terminal sequence has been determined by Edman degradation to NPVQAPELDKCGTAT, exhibiting a proline at the second and sixth position conserved in other polyphenol oxidases.

  6. [Kinetics of the catalytic oxidation of catechol in aqueous solutions of ceruloplasmin in the presence of Fe3+].

    PubMed

    Vorotyntsev, V M; Biriukovich, O K; Piatnitskiĭ, Iu I; Golodets, G I; Kachorovskiĭ, B V

    1982-03-01

    The kinetics of oxidation of catechol in aqueous solutions containing ceruloplasmin and Fe3+, were studied. It was found that Fe3+ at low concentrations accelerate the reaction. The inhibiting effect of high concentrations of Fe3+ is due to the formation of catalytically inactive enzyme complexes with catechol oxidation products. A mechanism of this process is proposed.

  7. A natural small molecule, catechol, induces c-Myc degradation by directly targeting ERK2 in lung cancer

    PubMed Central

    Lim, Do Young; Shin, Seung Ho; Lee, Mee-Hyun; Malakhova, Margarita; Kurinov, Igor; Wu, Qiong; Xu, Jinglong; Jiang, Yanan; Dong, Ziming; Liu, Kangdong; Lee, Kun Yeong; Bae, Ki Beom; Choi, Bu Young; Deng, Yibin; Bode, Ann; Dong, Zigang

    2016-01-01

    Various carcinogens induce EGFR/RAS/MAPK signaling, which is critical in the development of lung cancer. In particular, constitutive activation of extracellular signal-regulated kinase 2 (ERK2) is observed in many lung cancer patients, and therefore developing compounds capable of targeting ERK2 in lung carcinogenesis could be beneficial. We examined the therapeutic effect of catechol in lung cancer treatment. Catechol suppressed anchorage-independent growth of murine KP2 and human H460 lung cancer cell lines in a dose-dependent manner. Catechol inhibited ERK2 kinase activity in vitro, and its direct binding to the ERK2 active site was confirmed by X-ray crystallography. Phosphorylation of c-Myc, a substrate of ERK2, was decreased in catechol-treated lung cancer cells and resulted in reduced protein stability and subsequent down-regulation of total c-Myc. Treatment with catechol induced G1 phase arrest in lung cancer cells and decreased protein expression related to G1-S progression. In addition, we showed that catechol inhibited the growth of both allograft and xenograft lung cancer tumors in vivo. In summary, catechol exerted inhibitory effects on the ERK2/c-Myc signaling axis to reduce lung cancer tumor growth in vitro and in vivo, including a preclinical patient-derived xenograft (PDX) model. These findings suggest that catechol, a natural small molecule, possesses potential as a novel therapeutic agent against lung carcinogenesis in future clinical approaches. PMID:27167001

  8. The effect of catechol on human peripheral blood mononuclear cells (in vitro study).

    PubMed

    Bukowska, Bożena; Michałowicz, Jaromir; Marczak, Agnieszka

    2015-01-01

    Catechol also known as pyrocatechol or 1,2-dihydroxybenzene is formed endogenously in the organism from neurotransmitters including adrenaline, noradrenaline, and dopamine. It is also a metabolite of many drugs like DOPA, isoproterenol or aspirin and it is also formed in the environment during transformation of various xenobiotics. We evaluated in vitro the effect of catechol on the structure and function of human peripheral blood mononuclear cells (PBMCs). The cells were incubated with xenobiotic at concentration range from 2 to 500μg/mL for 1h. Human blood mononuclear cells were obtained from leucocyte-platelet buffy coat taken from healthy donors in the Blood Bank of Łódź, Poland. Using flow cytometry we have evaluated necrotic, apoptotic and morphological changes in PBMCs incubated with catechol. Moreover, we have estimated changes in reactive oxygen species (ROS) formation, protein carbonylation and lipid peroxidation in the cells studied. The compound studied provoked necrotic (from 250μg/mL), apoptotic (from 100μg/mL), and morphological changes (from 250μg/mL) in the incubated cells. We have also noted that catechol decreased H2DCF oxidation at 2 and 10μg/mL but at higher concentrations of 250 and 500μg/mL it caused statistically significant increase in the oxidation of this probe. We also observed an increase in lipid peroxidation (from 250μg/mL) and protein carbonylation (from 50μg/mL) of PBMCs. It was observed that catechol only at high concentrations was capable of inducing changes in PBMCs. The obtained results clearly showed that catechol may induce change in PBMCs only in the caste of poisoning with this compound. PMID:25528409

  9. Synthesis, structure and catechol-oxidase activity of copper(II) complexes of 17-hydroxy-16-(N-3-oxo-prop-1-enyl)amino steroids.

    PubMed

    Wegner, Rainer; Dubs, Manuela; Görls, Helmar; Robl, Christian; Schönecker, Bruno; Jäger, Ernst-G

    2002-09-01

    Copper is next to iron the most important element in the biological transport, storage and in redox reactions of dioxygen. A bioanalogous activation of dioxygen with copper complexes is used for catalytical epoxidation, allylic hydroxylation and oxidative coupling of aromatic substrates, for example. With stereochemical information in form of chiral ligands, enantioselective reactions may be possible. Another aspect of interest on copper catalyzed reactions with dioxygen is that the exact mechanism and biological function of some enzymes (especially catechol oxidase) is yet not fully clear. For studies mimicking the copper-containing catechol oxidase appropriate chiral steroid ligands with defined stereochemistry and conformation have been synthesized. The four diastereomeric 16,17-aminoalcohols of the 3-methoxy-estra-1,3,5(10)-triene series have been condensed with salicylic aldehyde and different beta-ketoenols to the chiral ligand types 1-5. These compounds with different steric and electronic properties and different arrangements of the neighboring hydroxy and nitrogen functions were reacted with copper(II) acetate to copper complexes. The structure of these complexes will be discussed. The bioanalogous oxidation of 3,5-di-tbutyl-catechol (dtbc) to the corresponding quinone was catalyzed by most of the complexes, indicating their ability to activate dioxygen. The trans configurations c and d showed an activity one magnitude higher than the cis configurations a and b. Comparing compounds with the same diastereomeric configuration, the main influence was that of the peripheral R(1-3) substituents at the beta-ketoenaminic group which are useful for the fine-tuning of the properties of the copper atoms like redox potential and Lewis acidity.

  10. Mechanochemical transformation of an organic ligand on mineral surfaces: the efficiency of birnessite in catechol degradation.

    PubMed

    Di Leo, Paola; Pizzigallo, Maria Donata Rosa; Ancona, Valeria; Di Benedetto, Francesco; Mesto, Ernesto; Schingaro, Emanuela; Ventruti, Gennaro

    2012-01-30

    The aim of this work is to investigate the efficiency of the phyllomanganate birnessite in degrading catechol after mechanochemical treatments. A synthesized birnessite and the organic molecule were grounded together in a high energy mill and the xenobiotic-mineral surface reactions induced by the grinding treatment have been investigated by means of X-ray powder diffraction, X-ray fluorescence, thermal analysis and spectroscopic techniques as well as high-performance liquid chromatography and voltammetric techniques. If compared to the simple contact between the birnessite and the organic molecule, mechanochemical treatments have revealed to be highly efficient in degrading catechol molecules, in terms both of time and extent. Due to the two phenolic groups of catechol and the small steric hindrance of the molecule, the extent of the mechanochemically induced degradation of catechol onto birnessite surfaces is quite high. The degradation mechanism mainly occurs via a redox reaction. It implies the formation of a surface bidentate inner-sphere complex between the phenolic group of the organic molecules and the Mn(IV) from the birnessite structure. Structural changes occur on the MnO(6) layers of birnessite as due to the mechanically induced surface reactions: reduction of Mn(IV), consequent formation of Mn(III) and new vacancies, and free Mn(2+) ions production.

  11. Mechanisms of product formation from the pyrolytic thermal degradation of catechol.

    PubMed

    Lomnicki, Slawomir; Truong, Hieu; Dellinger, Barry

    2008-09-01

    Catechol has been identified as one of the most abundant organic products in tobacco smoke and a major molecular precursor for semiquinone type radicals in the combustion of biomass material. The high-temperature gas-phase pyrolysis of catechol under hydrogen-rich and hydrogen-lean conditions was studied using a fused-silica tubular flow reactor coupled to an in-line GC/MS analytical system. Thermal degradation of catechol over temperature range of 250-1000 degrees C with a reaction time of 2.0s yielded a variety products including phenol, benzene, dibenzofuran, dibenzo-p-dioxin, phenylethyne, styrene, indene, anthracene, naphthalene, and biphenylene. Ortho-benzoquinone which is typically associated with the presence of semiquinone radicals was not observed and is proposed to be the result of fast decomposition reactions that lead to a variety of other reaction products. This is in contrast to the decomposition of hydroquinone that produced para-benzoquinone as the major product. A detailed mechanism of the degradation pathway of catechol is proposed.

  12. Degradation of catechol by ionizing radiation, ozone and the combined process ozone-electron-beam

    NASA Astrophysics Data System (ADS)

    Kubesch, K.; Zona, R.; Solar, S.; Gehringer, P.

    2005-03-01

    The influence of oxygen on the radiation-induced degradation of catechol (5×10 -4 mol dm -3, 55 mg dm -3) in distilled water was studied by gamma-radiolysis in the presence of air (A) and using air saturation (AS) during irradiation. Under AS conditions a complete decomposition of catechol as well as of the trihydroxybenzene products was obtained by a dose of 6 kGy, without air saturation all phenolic compounds were still present at 10 kGy. Using AS, at 12 kGy the total organic carbon (TOC) was reduced by 63%, without air saturation by 17.5%. Detoxification was only obtained in AS solutions. In the presence of the natural matrix of the local tap water no trihydroxybenzene products were formed and for total decomposition of catechol in AS solutions 9 kGy were required. The comparison of the effectiveness of an electron beam (EB), an ozone (O 3) and a combined EB/O 3 process showed, that by EB/O 3 the extent of catechol degradation corresponded to the sum of the decay with EB and with ozone, whereas for the chemical oxygen demand and TOC reduction a synergistic effect was evident.

  13. Development of an iron(II)-catalyzed aerobic catechol cleavage and biomimetic synthesis of betanidin.

    PubMed

    Guimond, Nicolas; Mayer, Peter; Trauner, Dirk

    2014-07-28

    An aerobic iron(II)-catalyzed cleavage of catechols was developed. This reaction allows for the preparation of 2-methoxy-2 H-pyrans that can be employed as versatile building blocks for synthesis. The utility of this biomimetic oxidative cleavage is featured in the synthesis of betanidin, a natural colorant with antioxidant properties.

  14. Association of Catechol-O-Methyltransferase (COMT) Polymorphism and Academic Achievement in a Chinese Cohort

    ERIC Educational Resources Information Center

    Yeh, Ting-Kuang; Chang, Chun-Yen; Hu, Chung-Yi; Yeh, Ting-Chi; Lin, Ming-Yeh

    2009-01-01

    Catechol-O-methyltransferase (COMT) is a methylation enzyme that catalyzes the degradation pathway and inactivation of dopamine. It is accepted widely as being involved in the modulation of dopaminergic physiology and prefrontal cortex (PFC) function. The COMT Val158Met polymorphism is associated with variation in COMT activity. COMT 158Met allele…

  15. Catechol-O-methyltransferase: a method for autoradiographic visualization of isozymes in cellogel

    SciTech Connect

    Brahe, C.; Crosti, N.; Meera Khan, P.; Serra, A.

    1984-02-01

    An electrophoretic procedure for separating the molecular forms of catechol-O-methyltransferase in cellulose acetate gel is described; the zones of enzyme activity were revealed by autoradiography. The electrophoretic patterns of the enzyme in several tissues and cell lines derived from four different species are presented.

  16. Polyaniline-iron oxide nanohybrid film as multi-functional label-free electrochemical and biomagnetic sensor for catechol.

    PubMed

    Chandra, Sudeshna; Lang, Heinrich; Bahadur, Dhirendra

    2013-09-17

    Polyaniline-iron oxide magnetic nanohybrid was synthesized and characterized using various spectroscopic, microstructural and electrochemical techniques. The smart integration of Fe3O4 nanoparticles within the polyaniline (PANI) matrix yielded a mesoporous nanohybrid (Fe3O4@PANI) with high surface area (94 m(2) g(-1)) and average pore width of 12.8 nm. Catechol is quasi-reversibly oxidized to o-quinone and reduced at the Fe3O4@PANI modified electrodes. The amperometric current response toward catechol was evaluated using the nanohybrid and the sensitivity and detection limit were found to be 312 μA μL(-1) and 0.2 nM, respectively. The results from electrochemical impedance spectroscopy (EIS) indicated that the increased solution resistance (Rs) was due to elevated adsorption of catechol on the modified electrodes. Photoluminescence spectra showed ligand-to-metal charge transfer (LMCT) between p-π orbitals of the phenolate oxygen in catechol and the d-σ* metal orbital of Fe3O4@PANI nanohybrid. Potential dependent spectroelectrochemical behavior of Fe3O4@PANI nanohybrid toward catechol was studied using UV/vis/NIR spectroscopy. The binding activity of the biomagnetic particles to catechol through Brownian relaxation was evident from AC susceptibility measurements. The proposed sensor was used for successful recovery of catechol in tap water samples.

  17. Growth of Actinobacillus pleuropneumoniae is promoted by exogenous hydroxamate and catechol siderophores.

    PubMed Central

    Diarra, M S; Dolence, J A; Dolence, E K; Darwish, I; Miller, M J; Malouin, F; Jacques, M

    1996-01-01

    Siderophores bind ferric ions and are involved in receptor-specific iron transport into bacteria. Six types of siderophores were tested against strains representing the 12 different serotypes of Actinobacillus pleuropneumoniae. Ferrichrome and bis-catechol-based siderophores showed strong growth-promoting activities for A. pleuropneumoniae in a disk diffusion assay. Most strains of A. pleuropneumoniae tested were able to use ferrichrome (21 of 22 or 95%), ferrichrome A (20 of 22 or 90%), and lysine-based bis-catechol (20 of 22 or 90%), while growth of 36% (8 of 22) was promoted by a synthetic hydroxamate, N5-acetyl-N5-hydroxy-L-ornithine tripeptide. A. pleuropneumoniae serotype 1 (strain FMV 87-682) and serotype 5 (strain 2245) exhibited a distinct yellow halo around colonies on Chrome Azurol S agar plates, suggesting that both strains can produce an iron chelator (siderophore) in response to iron stress. The siderophore was found to be neither a phenolate nor a hydroxamate by the chemical tests of Arnow and Csaky, respectively. This is the first report demonstrating the production of an iron chelator and the use of exogenous siderophores by A. pleuropneumoniae. A spermidine-based bis-catechol siderophore conjugated to a carbacephalosporin was shown to inhibit growth of A. pleuropneumoniae. A siderophore-antibiotic-resistant strain was isolated and shown to have lost the ability to use ferrichrome, synthetic hydroxamate, or catechol-based siderophores when grown under conditions of iron restriction. This observation indicated that a common iron uptake pathway, or a common intermediate, for hydroxamate- and catechol-based siderophores may exist in A. pleuropneumoniae. PMID:8975614

  18. Effects of Metal Oxides on a Fungal Laccase Activity and Catechol Transformation

    NASA Astrophysics Data System (ADS)

    Ahn, M.; Dec, J.; Bollag, J.

    2003-12-01

    The transformation of naturally occurring phenols to humic polymers is generally catalyzed by various phenoloxidases commonly present in soil. Some poorly crystalline metal oxides and hydroxides may also participate in these reactions. In this study, catechol (0.1 M) was incubated with a fungal laccase (950 unit/mL) in the presence of poorly crystalline minerals (ferrihydrite; 50 mg/mL: birnessite; 1 mg/mL: aluminum hydroxide; 50 mg/mL) to examine the interaction between these soil components under field conditions. Birnessite had an inhibitory effect on the laccase-mediated transformation of catechol (by up to 40%). Enzyme inhibition was possibly caused by the rapid production of humic-like polymers by birnessite. An additional inhibitory effect was caused by Manganese ion released from birnessite as it oxidized catechol (up to 70% loss in enzyme activity). In contrast to birnessite, aluminum hydroxide had an additive effect on the disappearance of catechol despite the rapid adsorption of the enzyme by this mineral (Xm=6.18μ g/mg). Apparently, the adsorbed laccase retained some enzyme activity. Ferrihydrite also had an additive effect on catechol transformation. However, as compared to aluminum hydroxide, ferrihydrite adsorbed less laccase (Xm=0.89μ g/mg) and more humic-like polymers. Unlike birnessite, aluminum hydroxide and ferrihydrite released negligible amounts of metal ions. In conclusion, under field conditions, phenoloxidase activity may be diminished by the presence of birnessite, but the presence of either ferrihydrite or aluminum hydroxide is less likely to inhibit enzyme activity, and may even enhance substrate transformation.

  19. Self-healable mussel-mimetic nanocomposite hydrogel based on catechol-containing polyaspartamide and graphene oxide.

    PubMed

    Wang, Bo; Jeon, Young Sil; Park, Ho Seok; Kim, Ji-Heung

    2016-12-01

    Stimuli-responsive and self-healing materials have a wide range of potential uses, and some significant research has focused on cross-linking of hydrogel materials by means of reversible coordination bonding. The resulting materials, however, tend to have poor mechanical properties with pronounced weakness and brittleness. In this work, we present a novel mussel-inspired graphene oxide(GO)-containing hydrogel based on modified polyaspartamide with γ-amino butyric acid (GABA), 3.4-dihydroxyphenethylamine (DOPA), and ethanolamine (EA), termed PolyAspAm(GABA/DOPA/EA). Here both GO nanosheets and boric acid (H3BO3) act as cross-linkers, interacting with polar functional groups of the PolyAspAm(GABA/DOPA/EA). Compared to PolyAspAm(GABA/DOPA/EA)/B(3+) gel without GO, the same containing 5wt% of GO yielded a 10-fold increase in both the storage and loss moduli, as well as 134% and 104% increases in the tensile and compressive strengths, respectively. In addition, the GO-containing polyaspartamide hydrogel exhibited rapid and autonomous self-healing property. Two types of bonding, boron-catechol coordination and strong hydrogen bonding interactions between PolyAspAm side chains and GO nanosheets, would impart the enhanced mechanical strength and good reversible gelation behavior upon pH stimulation to the hydrogel, making this biocompatible hydrogel a promising soft matter for biomedical applications. PMID:27612701

  20. Effects of Active-Site Modification and Quaternary Structure on the Regioselectivity of Catechol-O-Methyltransferase.

    PubMed

    Law, Brian J C; Bennett, Matthew R; Thompson, Mark L; Levy, Colin; Shepherd, Sarah A; Leys, David; Micklefield, Jason

    2016-02-18

    Catechol-O-methyltransferase (COMT), an important therapeutic target in the treatment of Parkinson's disease, is also being developed for biocatalytic processes, including vanillin production, although lack of regioselectivity has precluded its more widespread application. By using structural and mechanistic information, regiocomplementary COMT variants were engineered that deliver either meta- or para-methylated catechols. X-ray crystallography further revealed how the active-site residues and quaternary structure govern regioselectivity. Finally, analogues of AdoMet are accepted by the regiocomplementary COMT mutants and can be used to prepare alkylated catechols, including ethyl vanillin. PMID:26797714

  1. Reactivity and selectivity differences between catecholate and catechothiolate Ru complexes. Implications regarding design of stereoselective olefin metathesis catalysts.

    PubMed

    Khan, R Kashif M; Torker, Sebastian; Hoveyda, Amir H

    2014-10-15

    The origins of the unexpected finding that Ru catechothiolate complexes, in contrast to catecholate derivatives, promote exceptional Z-selective olefin metathesis reactions are elucidated. We show that species containing a catechothiolate ligand, unlike catecholates, preserve their structural integrity under commonly used reaction conditions. DFT calculations indicate that, whereas alkene coordination is the stereochemistry-determining step with catecholate complexes, it is through the metallacyclobutane formation that the identity of the major isomer is determined with catechothiolate systems. The present findings suggest that previous models for Z selectivity, largely based on steric differences, should be altered to incorporate electronic factors as well. PMID:25268949

  2. Reactivity and selectivity differences between catecholate and catechothiolate Ru complexes. Implications regarding design of stereoselective olefin metathesis catalysts.

    PubMed

    Khan, R Kashif M; Torker, Sebastian; Hoveyda, Amir H

    2014-10-15

    The origins of the unexpected finding that Ru catechothiolate complexes, in contrast to catecholate derivatives, promote exceptional Z-selective olefin metathesis reactions are elucidated. We show that species containing a catechothiolate ligand, unlike catecholates, preserve their structural integrity under commonly used reaction conditions. DFT calculations indicate that, whereas alkene coordination is the stereochemistry-determining step with catecholate complexes, it is through the metallacyclobutane formation that the identity of the major isomer is determined with catechothiolate systems. The present findings suggest that previous models for Z selectivity, largely based on steric differences, should be altered to incorporate electronic factors as well.

  3. Physico-chemical characterization of secondary organic aerosol derived from catechol and guaiacol as a model substance for atmospheric humic-like substances

    NASA Astrophysics Data System (ADS)

    Ofner, J.; Krüger, H.-U.; Grothe, H.; Schmitt-Kopplin, P.; Whitmore, K.; Zetzsch, C.

    2010-07-01

    Secondary organic aerosol was produced from the aromatic precursors catechol and guaiacol by reaction with ozone in the presence and absence of simulated sunlight and humidity and investigated for its properties as a proxy for humic-like substances (HULIS). Beside a small particle size, a relatively low molecular weight and typical optical features in the UV/VIS spectral range, HULIS contain a typical aromatic and/or olefinic chemical structure and highly oxidized functional groups within a high chemical diversity. Various methods were used to characterize the secondary organic aerosols obtained: Fourier transform infrared spectroscopy (FTIR) demonstrated the formation of different carbonyl containing functional groups as well as structural and functional differences between aerosols formed at different environmental conditions. UV/VIS spectroscopy of filter samples showed that the particulate matter absorbs far into the visible range up to more than 500 nm. Ultrahigh resolved mass spectroscopy (ICR-FT/MS) determined O/C-ratios between 0.3 and 1 and main molecular weights between 200 and 500 Da. Temperature-programmed-pyrolysis mass spectroscopy identified carboxylic acids and lactones as major functional groups. Particle sizing using CNC-DMPS demonstrated the formation of small particles during a secondary organic aerosol formation process. Particle imaging using field-emission-gun scanning electron microscopy (FEG-SEM) showed spherical particles, forming clusters and chains. Hence, secondary organic aerosols from catechol and guaiacol are appropriate model substances for studies of the processing of aromatic secondary organic aerosols and atmospheric HULIS on the laboratory scale.

  4. Cytochrome P450 isoforms catalyze formation of catechol estrogen quinones that react with DNA.

    PubMed

    Zhang, Yan; Gaikwad, Nilesh W; Olson, Kevin; Zahid, Muhammad; Cavalieri, Ercole L; Rogan, Eleanor G

    2007-07-01

    Accumulating evidence suggests that specific metabolites of estrogens, namely, catechol estrogen quinones, react with DNA to form adducts and generate apurinic sites, which can lead to the mutations that induce breast cancer. Oxidation of estradiol (E(2)) produces 2 catechol estrogens, 4-hydroxyestradiol (4-OHE(2)) and 2-OHE(2) among the major metabolites. These, in turn, are oxidized to the quinones, E(2)-3,4-quinone (E(2)-3,4-Q) and E(2)-2,3-Q, which can react with DNA. Oxidation of E(2) to 2-OHE(2) is mainly catalyzed by cytochrome P450 (CYP) 1A1, and CYP3A4, whereas oxidation of E(2) to 4-OHE(2) in extrahepatic tissues is mainly catalyzed by CYP1B1 as well as some CYP3As. The potential involvement of CYP isoforms in the further oxidation of catechols to semiquinones and quinones has, however, not been investigated in detail. In this project, to identify the potential function of various CYPs in oxidizing catechol estrogens to quinones, we used different recombinant human CYP isoforms, namely, CYP1A1, CYP1B1, and CYP3A4, with the scope of oxidizing the catechol estrogens 2-OHE(2) and 4-OHE(2) to their respective estrogen quinones, which then reacted with DNA. The depurinating adducts 2-OHE(2)-6-N3Ade, 4-OHE(2)-1-N3Ade, and 4-OHE(2)-1-N7Gua were observed in the respective reaction systems by ultraperformance liquid chromatography/tandem mass spectrometry. Furthermore, more than 100-fold higher levels of estrogen-glutathione (GSH) conjugates were detected in the reactions. Glutathione conjugates were observed, in much smaller amounts, when control microsomes were used. Depurinating adducts, as well as GSH conjugates, were obtained when E(2)-3,4-Q was incubated with CYP1B1 or control microsomes in a 30-minute reaction, further demonstrating that GSH is present in these recombinant enzyme preparations. These experiments demonstrated that CYP1A1, CYP1B1, and CYP3A4 are able to oxidize catechol estrogens to their respective quinones, which can further react with GSH

  5. Regulation of aromatics biodegradation by rhl quorum sensing system through induction of catechol meta-cleavage pathway.

    PubMed

    Yong, Yang-Chun; Zhong, Jian-Jiang

    2013-05-01

    The mechanism for quorum sensing (QS) regulation on aromatics degradation was investigated. Deletion of rhl QS system resulted in a significant decrease in aromatics biodegradation as well as the activity of catechol 2,3-dioxygenase (C23O, key enzyme for catechol meta-cleavage pathway) in Pseudomonas aeruginosa CGMCC1.860. Interestingly, this repression could be relieved by N-butyryl homoserine lactone (the signaling molecule of rhl QS system) addition. In accordance, the transcription level of nahH (the gene encoding C23O) and nahR (transcriptional activator) also responded to rhl perturbation in a similar way. The results indicated that rhl QS system positively controlled the catechol meta-cleavage pathway, and hence improved aromatics biodegradation. It suggested manipulation of QS system could be a promising strategy to tune the catechol cleavage pathway and to control aromatics biodegradation.

  6. The csbX gene of Azotobacter vinelandii encodes an MFS efflux pump required for catecholate siderophore export.

    PubMed

    Page, William J; Kwon, Elena; Cornish, Anthony S; Tindale, Anne E

    2003-11-21

    The csbX gene of Azotobacter vinelandii was regulated in an iron-repressible manner from a divergent promoter upstream of the catecholate siderophore biosynthesis (csb) operon and was predicted to encode an efflux pump of the major facilitator superfamily. Other proteins that were most similar to CsbX were encoded by genes found in the catecholate siderophore biosynthesis operons of Aeromonas hydrophila and Stigmatella aurantiaca. Inactivation of csbX resulted in 57-100% decrease in the amount of catecholates released when compared to the wild-type in iron-limited medium. CsbX was most important for the export of the high affinity chelator protochelin with the majority of the catecholates released by csbX mutants being the protochelin intermediates azotochelin and aminochelin.

  7. Differential inhibition of DNA synthesis in human T cells by the cigarette tar components hydroquinone and catechol.

    PubMed

    Li, Q; Aubrey, M T; Christian, T; Freed, B M

    1997-08-01

    Hydroquinone (HQ), catechol, and phenol exist in microgram quantities in cigarette tar and represent the predominant form of human exposure to benzene. Exposure of human T lymphoblasts (HTL) in vitro to 50 microM HQ or 50 microM catechol decreased IL-2-dependent DNA synthesis and cell proliferation by >90% with no effect on cell viability. Phenol had no effect on HTL proliferation at concentrations up to 1 mm. The addition of HQ or catechol to proliferating HTL blocked 3H-TdR uptake by >90% within 2 hr without significantly affecting 3H-UR uptake, suggesting that both compounds inhibit a rate-limiting step in DNA synthesis. However, the effects of HQ and catechol appear to involve different mechanisms. Ferric chloride (FeCl3) reversed the inhibitory effect of catechol, but not HQ, corresponding with the known ability of catechol to chelate iron. HQ, but not catechol, caused a decrease in transferrin receptor (TfR, CD71) expression, comparable to the level observed in IL-2-starved cells. HQ also inhibited DNA synthesis in cultures of transformed Jurkat T lymphocytes, primary and transformed fibroblasts, and mink lung epithelial cells, indicating that its antiproliferative effect was not restricted to IL-2 mediated proliferation. However, DNA synthesis by primary lymphocytes was more sensitive to HQ (IC50 = 6 microM) than that of the transformed Jurkat T cell line (IC50 = 37 microM) or primary human fibroblasts (IC50 = 45 microM), suggesting that normal lymphocytes may be particularly sensitive to HQ. The effects of HQ and catechol on DNA synthesis could be partially reversed by a combination of adenosine deoxyribose and guanosine deoxyribose, suggesting that both compounds may inhibit ribonucleotide reductase.

  8. Development of catechol 2,3-dioxygenase-specific primers for monitoring bioremediation by competitive quantitative PCR

    SciTech Connect

    Mesarch, M.B.; Nakatsu, C.H.; Nies, L.

    2000-02-01

    Benzene, toluene, xylenes, phenol, naphthalene, and biphenyl are among a group of compounds that have at least one reported pathway for biodegradation involving catechol 2,3-dioxygenase enzymes. Thus, detection of the corresponding catechol 2,3-dioxygenase genes can serve as a basis for identifying and quantifying bacteria that have these catabolic abilities. Primes that can successfully amplify a 238-bp catechol 2,3-dioxygenase gene fragment from eight different bacteria are described. The identities of the amplicons were confirmed by hybridization with a 238-bp catechol 2,3-dioxygenase probe. The detection limit was 10{sup 2} to 10{sup 3} gene copies, which was lowered to 10{sup 0} to 10{sup 1} gene copies of hybridization. Using the dioxygenase-specific primers, an increase in catechol 2,3-dioxygenase genes was detected in petroleum-amended soils. The dioxygenase genes were enumerated by competitive quantitative PCR and a 163-bp competitor that was amplified using the same primers. Target and competitor sequences had identical amplification kinetics. Potential PCR inhibitors that could coextract with DNA, nonamplifying DNA, soil factors (humics), and soil pollutants (toluene) did not impact enumeration. Therefore, this technique can be used to accurately and reproducibly quantify catechol 2,3-dioxygenase genes in complex environments such as petroleum-contaminated soil. Direct, non-cultivation-based molecular techniques for detecting and enumerating microbial pollutant-biodegrading genes in environmental samples are powerful tools for monitoring bioremediation and developing field evidence in support of natural attenuation.

  9. Effects of biochar and the geophagous earthworm Metaphire guillelmi on fate of (14)C-catechol in an agricultural soil.

    PubMed

    Shan, Jun; Wang, Yongfeng; Gu, Jianqiang; Zhou, Wenqiang; Ji, Rong; Yan, Xiaoyuan

    2014-07-01

    Both biochar and earthworms can exert influence on behaviors of soil-borne monomeric phenols in soil; however, little was known about the combined effects of biochar and earthworm activities on fate of these chemicals in soil. Using (14)C-catechol as a representative, the mineralization, transformation and residue distribution of phenolic humus monomer in soil amended with different amounts of biochar (0%, 0.05%, 0.5%, and 5%) without/with the geophagous earthworm Metaphire guillelmi were investigated. The results showed biochar at amendment rate <0.5% did not affect (14)C-catechol mineralization, whereas 5% biochar amendment significantly inhibited the mineralization. Earthworms did not affect the mineralization of (14)C-catechol in soil amended with <0.5% biochar, but significantly enhanced the mineralization in 5% biochar amended soil when they were present in soil for 9 d. When earthworms were removed from the soil, the mineralization of (14)C-catechol was significantly lower than that of in earthworm-free soil indicating that (14)C-catecholic residues were stabilized during their passage through earthworm gut. The assimilation of (14)C by earthworms was low (1.2%), and was significantly enhanced by biochar amendment, which was attributed to the release of biochar-associated (14)C-catecholic residues during gut passage of earthworm.

  10. Crystallization and preliminary X-ray diffraction studies of a catechol-O-methyltransferase/inhibitor complex

    SciTech Connect

    Rodrigues, M. L.; Bonifácio, M. J.; Soares-da-Silva, P.; Carrondo, M. A.; Archer, M.

    2005-01-01

    Catechol-O-methyltransferase has been co-crystallized with a novel inhibitor, which has potential therapeutic application in the Parkinson’s disease therapy. Inhibitors of the enzyme catechol-O-methyltransferase (COMT) are used as co-adjuvants in the therapy of Parkinson’s disease. A recombinant form of the soluble cytosolic COMT from rat has been co-crystallized with a new potent inhibitor, BIA 8-176 [(3,4-dihydroxy-2-nitrophenyl)phenylmethanone], by the vapour-diffusion method using PEG 6K as precipitant. Crystals diffract to 1.6 Å resolution on a synchrotron-radiation source and belong to the monoclinic space group P2{sub 1}, with unit-cell parameters a = 52.77, b = 79.63, c = 61.54 Å, β = 91.14°.

  11. Synthesis, crystal structure and EPR spectra of cis-dioxo-molybdenum(V) with catechol ligand

    NASA Astrophysics Data System (ADS)

    Lu, Xiaoming; Liu, Shuncheng; Mao, Xian; Bu, Xianhe

    2001-05-01

    The cis-dioxo-molybdenum(V) complex anion [Mo (V)O 2(C 6H 4O 2) 2] 3- was obtained by the reaction of tetra-butyl ammonium β-octamolybdate with catechol and ethylenediamine in the mixed solvent of CH 3OH and CH 3CN, and characterized by IR, NM, UV, EPR spectroscopy and X-ray diffraction with its discrete (NH 2CH 2CH 2NH 3) + cations. The determination of single crystal X-ray analysis revealed that the metal center exhibits distorted octahedral co-ordination with cis dioxo catechol. The result of essentially the same of EPR spectra shown by the complex and flavoenzyme suggests that the title complex anion and flavoenzyme have related structure feature.

  12. Preparation of ultrathin, robust protein microcapsules through template-mediated interfacial reaction between amine and catechol groups.

    PubMed

    Wang, Xiaoli; Shi, Jiafu; Jiang, Zhongyi; Li, Zheng; Zhang, Wenyan; Song, Xiaokai; Ai, Qinghong; Wu, Hong

    2013-11-11

    A novel approach to the synthesis of protein microcapsules is developed through template-mediated interfacial reaction. Protein-doped CaCO3 templates are first synthetized via coprecipitation and then coated with a catechol-containing alginate (AlgDA) layer. Afterward, the templates are exposed to ethylenediamine tetraacetic acid disodium (EDTA) solution to dissolve CaCO3. During CaCO3 dissolution, the generated CO2 gas pushes protein molecules moving to the AlgDA layer, and thereby Michael addition and Schiff base reactions proceed, forming the shell of protein microcapsules. Three kinds of proteins, namely, bovine serum albumin, catalase, and protamine sulfate, are utilized. The shell thickness of microcapsule varies from 25 to 82 nm as the doping amount of protein increased from 2 to 6 mg per 66 mg CaCO3. The protein microcapsules have a robust but flexible shell and can be reversibly deformed upon exposure to osmotic pressure. The bioactivity of protein microcapsules is demonstrated through enzymatic catalysis experiments. The protein microcapsules remain about 80% enzymatic activity of the equivalent free protein. Hopefully, our approach could be extended to many other applications such as drug/gene delivery, tissue scaffolds, and catalysis due to the universality of Michael reaction and Schiff base reactions.

  13. Inhibition of catechol-O-methyltransferase increases estrogen-DNA adduct formation

    PubMed Central

    Zahid, Muhammad; Saeed, Muhammad; Lu, Fang; Gaikwad, Nilesh; Rogan, Eleanor; Cavalieri, Ercole

    2007-01-01

    The association found between breast cancer development and prolonged exposure to estrogens suggests that this hormone is of etiologic importance in the causation of the disease. Studies on estrogen metabolism, formation of DNA adducts, carcinogenicity, cell transformation and mutagenicity have led to the hypothesis that reaction of certain estrogen metabolites, predominantly catechol estrogen-3,4-quinones, with DNA forms depurinating adducts [4-OHE1(E2)-1-N3Ade and 4-OHE1(E2)-1-N7Gua]. These adducts cause mutations leading to the initiation of breast cancer. Catechol-O-methyltransferase (COMT) is considered an important enzyme that protects cells from the genotoxicity and cytotoxicity of catechol estrogens, by preventing their conversion to quinones. The goal of the present study was to investigate the effect of COMT inhibition on the formation of depurinating estrogen-DNA adducts. Immortalized human breast epithelial MCF-10F cells were treated with 4-OHE2 (0.2 or 0.5 μM) for 24 h at 120, 168, 216, and 264 h post-plating or one time at 1–30 μM 4-OHE2 with or without the presence of COMT inhibitor (Ro41-0960). The culture media were collected at each point, extracted by solid-phase extraction and analyzed by HPLC connected with a multichannel electrochemical detector. The results demonstrate that MCF-10F cells oxidize 4-OHE2 to E1(E2)-3,4-Q, which react with DNA to form the depurinating N3Ade and N7Gua adducts. The COMT inhibitor Ro41-0960 blocked the methoxylation of catechol estrogens, with concomitant 3–4 fold increases in the levels of the depurinating adducts. Thus, low activity of COMT leads to higher levels of depurinating estrogen-DNA adducts that can induce mutations and initiate cancer. PMID:17964424

  14. Computational Investigation of the Interplay of Substrate Positioning and Reactivity in Catechol O-Methyltransferase

    PubMed Central

    Patra, Niladri; Ioannidis, Efthymios I.

    2016-01-01

    Catechol O-methyltransferase (COMT) is a SAM- and Mg2+-dependent methyltransferase that regulates neurotransmitters through methylation. Simulations and experiments have identified divergent catecholamine substrate orientations in the COMT active site: molecular dynamics simulations have favored a monodentate coordination of catecholate substrates to the active site Mg2+, and crystal structures instead preserve bidentate coordination along with short (2.65 Å) methyl donor-acceptor distances. We carry out longer dynamics (up to 350 ns) to quantify interconversion between bidentate and monodentate binding poses. We provide a systematic determination of the relative free energy of the monodentate and bidentate structures in order to identify whether structural differences alter the nature of the methyl transfer mechanism and source of enzymatic rate enhancement. We demonstrate that the bidentate and monodentate binding modes are close in energy but separated by a 7 kcal/mol free energy barrier. Analysis of interactions in the two binding modes reveals that the driving force for monodentate catecholate orientations in classical molecular dynamics simulations is derived from stronger electrostatic stabilization afforded by alternate Mg2+ coordination with strongly charged active site carboxylates. Mixed semi-empirical-classical (SQM/MM) substrate C-O distances (2.7 Å) for the bidentate case are in excellent agreement with COMT X-ray crystal structures, as long as charge transfer between the substrates, Mg2+, and surrounding ligands is permitted. SQM/MM free energy barriers for methyl transfer from bidentate and monodentate catecholate configurations are comparable at around 21–22 kcal/mol, in good agreement with experiment (18–19 kcal/mol). Overall, the work suggests that both binding poses are viable for methyl transfer, and accurate descriptions of charge transfer and electrostatics are needed to provide balanced relative barriers when multiple binding poses are

  15. Computational Investigation of the Interplay of Substrate Positioning and Reactivity in Catechol O-Methyltransferase.

    PubMed

    Patra, Niladri; Ioannidis, Efthymios I; Kulik, Heather J

    2016-01-01

    Catechol O-methyltransferase (COMT) is a SAM- and Mg2+-dependent methyltransferase that regulates neurotransmitters through methylation. Simulations and experiments have identified divergent catecholamine substrate orientations in the COMT active site: molecular dynamics simulations have favored a monodentate coordination of catecholate substrates to the active site Mg2+, and crystal structures instead preserve bidentate coordination along with short (2.65 Å) methyl donor-acceptor distances. We carry out longer dynamics (up to 350 ns) to quantify interconversion between bidentate and monodentate binding poses. We provide a systematic determination of the relative free energy of the monodentate and bidentate structures in order to identify whether structural differences alter the nature of the methyl transfer mechanism and source of enzymatic rate enhancement. We demonstrate that the bidentate and monodentate binding modes are close in energy but separated by a 7 kcal/mol free energy barrier. Analysis of interactions in the two binding modes reveals that the driving force for monodentate catecholate orientations in classical molecular dynamics simulations is derived from stronger electrostatic stabilization afforded by alternate Mg2+ coordination with strongly charged active site carboxylates. Mixed semi-empirical-classical (SQM/MM) substrate C-O distances (2.7 Å) for the bidentate case are in excellent agreement with COMT X-ray crystal structures, as long as charge transfer between the substrates, Mg2+, and surrounding ligands is permitted. SQM/MM free energy barriers for methyl transfer from bidentate and monodentate catecholate configurations are comparable at around 21-22 kcal/mol, in good agreement with experiment (18-19 kcal/mol). Overall, the work suggests that both binding poses are viable for methyl transfer, and accurate descriptions of charge transfer and electrostatics are needed to provide balanced relative barriers when multiple binding poses are

  16. Adsorptive removal of aniline by granular activated carbon from aqueous solutions with catechol and resorcinol.

    PubMed

    Suresh, S; Srivastava, V C; Mishrab, I M

    2012-01-01

    In the present paper, the removal of aniline by adsorption process onto granular activated carbon (GAC) is reported from aqueous solutions containing catechol and resorcinol separately. The Taguchi experimental design was applied to study the effect of such parameters as the initial component concentrations (C(0,i)) of two solutes (aniline and catechol or aniline and resorcinol) in the solution, temperature (T), adsorbent dosage (m) and contact time (t). The L27 orthogonal array consisting of five parameters each with three levels was used to determine the total amount of solutes adsorbed on GAC (q(tot), mmol/g) and the signal-to-noise ratio. The analysis of variance (ANOVA) was used to determine the optimum conditions. Under these conditions, the ANOVA shows that m is the most important parameter in the adsorption process. The most favourable levels of process parameters were T = 303 K, m = 10 g/l and t = 660 min for both the systems, qtot values in the confirmation experiments carried out at optimum conditions were 0.73 and 0.95 mmol/g for aniline-catechol and aniline-resorcinol systems, respectively.

  17. Secondary Organic Aerosol formation from the gas-phase reaction of catechol with ozone

    NASA Astrophysics Data System (ADS)

    Coeur-Tourneur, C.; Tomas, A.; Guilloteau, A.; Henry, F.; Ledoux, F.; Visez, N.; Riffault, V.; Wenger, J. C.; Bedjanian, Y.; Foulon, V.

    2009-04-01

    The formation of secondary organic aerosol from the gas-phase reaction of catechol (1,2-dihydroxybenzene) with ozone has been studied in two smog chambers (at the LPCA in France and at the CRAC in Ireland). Aerosol production was monitored using a scanning mobility particle sizer. The overall organic aerosol yield (Y) was determined as the ratio of the suspended aerosol mass corrected for wall losses (Mo) to the total reacted catechol concentrations, assuming a particle density of 1.4 g cm-3. Analysis of the data clearly shows that Y is a strong function of Mo and that secondary organic aerosol formation can be expressed by a one-product gas/particle partitioning absorption model. The aerosol formation is affected by the initial catechol concentration, which leads to aerosol yields ranging from 17% to 86%. The aerosol yields determined in the LPCA and CRAC smog chambers were comparable and were also in accordance with those determined in a previous study performed in EUPHORE (EUropean PHOto REactor, Spain).

  18. Catechol-initiated polyethers: multifunctional hydrophilic ligands for PEGylation and functionalization of metal oxide nanoparticles.

    PubMed

    Wilms, Valerie S; Bauer, Heiko; Tonhauser, Christine; Schilmann, Anna-Maria; Müller, Marc-Christian; Tremel, Wolfgang; Frey, Holger

    2013-01-14

    Bifunctional CA-PEG (catechol-poly(ethylene glycol)) and multifunctional CA-PEG-PGA/PEVGE (poly(glycidyl amine)/poly(ethylene glycol vinyl glycidyl ether)) ligands for the functionalization and solubilization of nanoparticles are introduced. Tunable polymers with polydispersities <1.25 and molecular weights in the range 500-7700 g mol(-1) containing a catechol moiety for conjugation to metal oxide nanoparticles were prepared. The functional PEG ligands were synthesized starting from the acetonide-protected catechol initiator 2,2-dimethyl-1,3-benzodioxole-5-propanol (CA-OH) for oxyanionic polymerization. CA-OH was used both for homopolymerization of ethylene oxide (EO) as well as copolymerization with functional epoxides N,N-diallyl glycidyl amine (DAGA), releasing primary amino groups and ethylene glycol vinyl glycidyl ether (EVGE), exhibiting a double bond for click-type reactions, to generate CA-PEG and CA-PEG-PGA/PEVGE. We demonstrate the potential of the functional ligands by binding to MnO nanoparticles, rendering the PEGylated nanoparticles highly stable in aqueous environment. Furthermore, addressability of the functional groups has been proven, for example, by coupling with fluoresceine isothiocyanate (FITC), to allow for optical monitoring of the nanoparticle fate in biological systems.

  19. Hydroxylation of phenol to catechol by Candida tropicalis: involvement of cytochrome P450.

    PubMed

    Stiborová, M; Suchá, V; Miksanová, M; Páca, J; Páca, J

    2003-06-01

    Microsomal preparations isolated from yeast Candida tropicalis (C. tropicalis) grown on three different media with or without phenol were isolated and characterized for the content of cytochrome P450 (CYP) (EC 1.14.15.1). While no CYP was detected in microsomes of C. tropicalis grown on glucose as the carbon source, evidence was obtained for the presence of the enzyme in the microsomes of C. tropicalis grown on media containing phenol. Furthermore, the activity of NADPH: CYP reductase, another enzyme of the microsomal CYP-dependent system, was markedly higher in cells grown on phenol. Microsomes of these cells oxidized phenol. The major metabolite formed from phenol by microsomes of C. tropicalis was characterized by UV/vis absorbance and mass spectroscopy as well as by the chromatographic properties on HPLC. The characteristics are identical to those of catechol. The formation of catechol was inhibited by CO, the inhibitor of CYP, and correlated with the content of cytochrome P450 in microsomes. These results, the first report showing the ring hydroxylation of phenol to catechol with the microsomal enzyme system of C. tropicalis, strongly suggest that CYP-catalyzed reactions are responsible for this hydroxylation. The data demonstrate the progress in resolving the enzymes responsible for the first step of phenol degradation by the C. tropicalis strain.

  20. Magnetic catechol-chitosan with bioinspired adhesive surface: preparation and immobilization of ω-transaminase.

    PubMed

    Ni, Kefeng; Zhou, Xu; Zhao, Li; Wang, Hualei; Ren, Yuhong; Wei, Dongzhi

    2012-01-01

    The magnetic chitosan nanocomposites have been studied intensively and been used practically in various biomedical and biological applications including enzyme immobilization. However, the loading capacity and the remained activity of immobilized enzyme based on existing approaches are not satisfied. Simpler and more effective immobilization strategies are needed. Here we report a simple catechol modified protocol for preparing a novel catechol-chitosan (CCS)-iron oxide nanoparticles (IONPs) composites carrying adhesive moieties with strong surface affinity. The ω-transaminase (ω-TA) was immobilized onto this magnetic composite via nucleophilic reactions between catechol and ω-TA. Under optimal conditions, 87.5% of the available ω-TA was immobilized on the composite, yielding an enzyme loading capacity as high as 681.7 mg/g. Furthermore, the valuation of enzyme activity showed that ω-TA immobilized on CCS-IONPs displayed enhanced pH and thermal stability compared to free enzyme. Importantly, the immobilized ω-TA retained more than 50% of its initial activity after 15 repeated reaction cycles using magnetic separation and 61.5% of its initial activity after storage at 4°C in phosphate buffered saline (PBS) for 15 days. The results suggested that such adhesive magnetic composites may provide an improved platform technology for bio-macromolecules immobilized.

  1. Reaction Kinetics of Catechol (1,2-Benzenediol) and Guaiacol (2-Methoxyphenol) with Ozone.

    PubMed

    Zein, Atallah El; Coeur, Cécile; Obeid, Emil; Lauraguais, Amélie; Fagniez, Thomas

    2015-07-01

    The kinetic reactions of 1,2-benzenediol (catechol) and 2-methoxyphenol (guaiacol) with ozone were studied in a simulation chamber (8 m(3)) under dark conditions. The rate coefficients were measured at 294 ± 2 K, atmospheric pressure and dry conditions (relative humidity, RH < 1%), except for 1,2-benzenediol where they were also measured as a function of relative humidity (RH = 1-80%). The concentrations of organic compounds were followed by a PTR-ToF-MS for a continuous monitoring of gas-phase species. The O3 rate coefficients were obtained using both the pseudo-first-order and relative rate methods. The values (in cm(3) molecule(-1) s(-1)) determined for catechol and guaiacol under dry conditions are (13.5 ± 1.1) × 10(-18) and (0.40 ± 0.31) × 10(-18), respectively. The rate coefficient of catechol was found to be independent of RH below 20% and above 60%, whereas for RH between 20% and 60% it decreases with increasing RH. The determined rate coefficients have been used to evaluate the atmospheric lifetime of each compound with respect to O3. To our knowledge, this study represents the first determination of the ozone rate coefficient with guaiacol and is also the first kinetic investigation for the influence of the relative humidity on the oxygenated aromatic ozonolysis.

  2. Versatile tuning of supramolecular hydrogels through metal complexation of oxidation-resistant catechol-inspired ligands.

    PubMed

    Menyo, Matthew S; Hawker, Craig J; Waite, J Herbert

    2013-11-21

    The mussel byssal cuticle employs DOPA-Fe(3+) complexation to provide strong, yet reversible crosslinking. Synthetic constructs employing this design motif based on catechol units are plagued by oxidation-driven degradation of the catechol units and the requirement for highly alkaline pH conditions leading to decreased performance and loss of supramolecular properties. Herein, a platform based on a 4-arm poly(ethylene glycol) hydrogel system is used to explore the utility of DOPA analogues such as the parent catechol and derivatives, 4-nitrocatechol (nCat) and 3-hydroxy-4-pyridinonone (HOPO), as structural crosslinking agents upon complexation with metal ions. HOPO moieties are found to hold particular promise, as robust gelation with Fe(3+) occurs at physiological pH and is found to be largely resistant to oxidative degradation. Gelation is also shown to be triggered by other biorelevant metal ions such as Al(3+), Ga(3+) and Cu(2+) which allows for tuning of the release and dissolution profiles with potential application as injectable delivery systems.

  3. Versatile tuning of supramolecular hydrogels through metal complexation of oxidation-resistant catechol-inspired ligands

    PubMed Central

    Menyo, Matthew S.

    2013-01-01

    The mussel byssal cuticle employs DOPA-Fe3+ complexation to provide strong, yet reversible crosslinking. Synthetic constructs employing this design motif based on catechol units are plagued by oxidation-driven degradation of the catechol units and the requirement for highly alkaline pH conditions leading to decreased performance and loss of supramolecular properties. Herein, a platform based on a 4-arm poly(ethylene glycol) hydrogel system is used to explore the utility of DOPA analogues such as the parent catechol and derivatives, 4-nitrocatechol (nCat) and 3-hydroxy-4-pyridinonone (HOPO), as structural crosslinking agents upon complexation with metal ions. HOPO moieties are found to hold particular promise, as robust gelation with Fe3+ occurs at physiological pH and is found to be largely resistant to oxidative degradation. Gelation is also shown to be triggered by other biorelevant metal ions such as Al3+, Ga3+ and Cu2+ which allows for tuning of the release and dissolution profiles with potential application as injectable delivery systems. PMID:24285981

  4. Dinuclear copper complexes with imidazole derivative ligands: a theoretical study related to catechol oxidase activity.

    PubMed

    Martínez, Ana; Membrillo, Ingrid; Ugalde-Saldívar, Victor M; Gasque, Laura

    2012-07-19

    Catechol oxidase is a very important and interesting metalloprotein. In spite of the efforts to understand the reaction mechanism of this protein, there are important questions that remain unanswered concerning the catalytic mechanism of this enzyme. In this article, dinuclear copper compounds are used as biomimetic models of catechol oxidase to study plausible reaction paths. These dinuclear copper(II) complexes have distant metal centers (of 7.5 Å approximately) and superior catalytic activity to that of many dicopper complexes with shorter Cu-Cu distances. One mononuclear copper(II) complex is also analyzed in this investigation in order to see the influence of the two metal centers in the catalytic activity. Density functional theory calculations were performed to obtain optimized structures, vertical ionization energies, vertical electron affinities, the electrodonating power (ω(-)), the electroaccepting power (ω(+)) and the energy difference of several reaction paths. The K(M) experimental results that were previously reported compare well with the electroaccepting power (ω(+)) of the copper compounds that are included in this article, indicating that this index is useful for the interpretation of the electron transfer capacity and therefore the catalytic activity. The catechol moiety coordinates to only one Cu ion, but two metal atoms are needed in order to have a good electron acceptor capacity of the biomimetic models.

  5. Magnetic catechol-chitosan with bioinspired adhesive surface: preparation and immobilization of ω-transaminase.

    PubMed

    Ni, Kefeng; Zhou, Xu; Zhao, Li; Wang, Hualei; Ren, Yuhong; Wei, Dongzhi

    2012-01-01

    The magnetic chitosan nanocomposites have been studied intensively and been used practically in various biomedical and biological applications including enzyme immobilization. However, the loading capacity and the remained activity of immobilized enzyme based on existing approaches are not satisfied. Simpler and more effective immobilization strategies are needed. Here we report a simple catechol modified protocol for preparing a novel catechol-chitosan (CCS)-iron oxide nanoparticles (IONPs) composites carrying adhesive moieties with strong surface affinity. The ω-transaminase (ω-TA) was immobilized onto this magnetic composite via nucleophilic reactions between catechol and ω-TA. Under optimal conditions, 87.5% of the available ω-TA was immobilized on the composite, yielding an enzyme loading capacity as high as 681.7 mg/g. Furthermore, the valuation of enzyme activity showed that ω-TA immobilized on CCS-IONPs displayed enhanced pH and thermal stability compared to free enzyme. Importantly, the immobilized ω-TA retained more than 50% of its initial activity after 15 repeated reaction cycles using magnetic separation and 61.5% of its initial activity after storage at 4°C in phosphate buffered saline (PBS) for 15 days. The results suggested that such adhesive magnetic composites may provide an improved platform technology for bio-macromolecules immobilized. PMID:22815930

  6. Synthesis, structure, spectra and reactivity of iron(III) complexes of imidazole and pyrazole containing ligands as functional models for catechol dioxygenases.

    PubMed

    Dhanalakshmi, Thirumanasekaran; Suresh, Eringathodi; Palaniandavar, Mallayan

    2009-10-21

    A series of new 1 : 1 iron(iii) complexes of the type [Fe()Cl(3)], where is a tridentate 3N donor ligand, has been isolated and studied as functional models for catechol dioxygenases. The ligands (1-methyl-1H-imidazol-2-ylmethyl)pyrid-2-ylmethyl-amine (), N,N-dimethyl-N'-(1-methyl-1H-imidazol-2-ylmethyl)ethane-1,2-diamine () and N-(1-methyl-1H-imidazol-2-ylmethyl)-N'-phenylethane-1,2-diamine () are linear while the ligands tris(1-pyrazolyl)methane (), tris(3,5-dimethyl-1-pyrazolyl)methane () and tris(3-iso-propylpyrazolyl)methane () are tripodal ones. All the complexes have been characterized by spectral and electrochemical methods. The X-ray crystal structure of the dinuclear catecholate adduct [Fe()(TCC)](2)O, where TCC(2-) is a tetrachlorocatecholate dianion, has been successfully determined. In this complex both the iron(iii) atoms are bridged by a mu-oxo group and each iron(iii) center possesses a distorted octahedral coordination geometry in which the ligand is facially coordinated and the remaining coordination sites are occupied by the TCC(2-) dianion. Spectral studies suggest that addition of a base like Et(3)N induces the mononuclear complex species [Fe()(TCC)Cl] to dimerize forming a mu-oxo-bridged complex. The spectral and electrochemical properties of the catecholate adducts of the complexes generated in situ reveal that a systematic variation in the ligand donor atom type significantly influences the Lewis acidity of the iron(iii) center and hence the interaction of the complexes with simple and substituted catechols. The 3,5-di-tert-butylcatecholate (DBC(2-)) adducts of the type [Fe()(DBC)Cl], where is a linear tridentate ligand (), undergo mainly oxidative intradiol cleavage of the catechol in the presence of dioxygen. Also, the extradiol-to-intradiol product selectivity (E : I) is enhanced upon removal of the coordinated chloride ion in these adducts to obtain [Fe()(DBC)(Sol)](+) and upon incorporating coordinated N-methylimidazolyl nitrogen in

  7. Effects of the co-carcinogen catechol on benzo(a)pyrene metabolism and DNA adduct formation in mouse skin

    SciTech Connect

    Melikian, A.A.; Leszczynska, J.M.; Hecht, S.S.; Hoffmann, D.

    1986-01-01

    We have studied the effects of the co-carcinogen catechol (1,2-dihydroxybenzene) on the metabolic activation of (/sup 3/H) benzo(a)pyrene (BaP) in mouse skin, in vivo and on the binding of BaP metabolites to DNA and protein at intervals from 0.5-24 h. Upon topical application of 0.015 mg (/sup 3/H)BaP and 0.25 or 0.5 mg catechol per mouse, catechol had little effect on the total amount of (/sup 3/H)BaP metabolized in mouse skin, but it affected the relative proportions of (/sup 3/H)BaP metabolites. Catechol (0.5 mg/mouse) decreased the proportion of water-soluble (/sup 3/H)BaP metabolites, ethyl acetate-soluble polar metabolites and quinones, but doubled the levels of unconjugated 3-hydroxy-BaP at all measured intervals after treatment. Catechol also caused a small increase in the levels of trans-7,8-dihydroxy-7,8-dihydroBaP and trans-9,10-dihydroxy-9,10-dihydroBaP 0.5 h after treatment. Two hours after treatment, the levels of these metabolites subsided to those of the controls. Catechol did not affect the levels of glutathione conjugates of BaP. However, it caused a decrease in glucuronide and sulphate conjugate formation from BaP. Catechol caused an approximately 2-fold increase in the formation of anti-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydroBaP (BPDE) DNA adducts and elevated the ratio of anti-syn-BPDE-DNA adducts 1.6 to 2.9-fold. Catechol treatment increased the radioactivity associated with epidermal proteins after (/sup 3/H)BaP application. Because catechol increased levels of 3-hydroxyBaP, we considered the possibility that 3-hydroxyBaP might enhance the tumor initiating activities of BaP or BPDE in mouse skin; a bioassay demonstrated that this was not the case. The results of this study indicate that one important effect of catechol related to its co-carcinogenicity is its ability to enhance formation of anti-BPDE-DNA adducts in mouse skin.

  8. Polymer-supported sulfonated catechol and linear catechol amide ligands and their use in selective metal ion removal recovery from aqueous solutions

    DOEpatents

    Fish, Richard H.

    1998-01-01

    The present invention concerns the synthesis of several biomimetically important polymer-supported, sulfonated catechol (PS-CATS), sulfonated bis-catechol linear amide (PS-2-6-LICAMS) and sulfonated 3,3-linear tris-catechol amide (PS-3,3-LICAMS) ligands, which chemically bond to modified 6% crosslinked macroporous polystyrene-divinylbenzene beads (PS-DVB). These polymers are useful for the for selective removal and recovery of environmentally and economically important metal ions from aqueous solution, as a function of pH. The Fe.sup.3+ ion selectivity shown for PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads in competition with a similar concentration of Cu.sup.2+, Zn.sup.2+, Mn.sup.2+, Ni.sup.2+, Mg.sup.2+, Al.sup.3+, and Cr.sup.3+ ions at pH 1-3. Further, the metal ion selectivity is changed at higher pH values in the absence of Fe.sup.3+ (for example, Hg.sup.2+ at pH 3). The rates of selective removal and recovery of the trivalent metal ions, e.g. Fe.sup.3+ Al.sup.3+ ion etc. with the PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads used determined are useful as well as equilibrium selectivity coefficient (K.sub.m) values for all metal competition studies. The chelate effect for the predisposed octahedral PS-3,3-LICAMS polymer pendant ligand is the reason that this ligand has a more pronounced selectivity for Fe.sup.3+ ion in comparison to the PS-CATS polymer beads. The predisposed square planar PS-2,6-LICAMS series of polymer pendant ligands are more selective to divalent metal ions Cu.sup.2+, Zn.sup.2+, Mn.sup.2+, Ni.sup.2+, and Mg.sup.2+, than either PS-CATS or PS-3,3-LICAMS. However, Fe.sup.3+ ion still dominates in competition with other divalent and trivalent metal ions. In the absence of Fe.sup.3+, the polymer ligand is selective for Al.sup.3+, Cu.sup.2+ or Hg.sup.2+. The changing of the cavity size from two CH.sub.2 groups to six CH.sub.2 groups in the PS-2-6-LICAMS polymer pendant ligand series does not effect the order of metal ion

  9. Polymer-supported sulfonated catechol and linear catechol amide ligands and their use in selective metal ion removal and recovery from aqueous solutions

    DOEpatents

    Fish, Richard H.

    1997-01-01

    The present invention concerns the synthesis of several biomimetically important polymer-supported, sulfonated catechol (PS-CATS), sulfonated bis-catechol linear amide (PS-2-6-LICAMS) and sulfonated 3,3-linear tris-catechol amide (PS-3,3-LICAMS) ligands, which chemically bond to modified 6% crosslinked macroporous polystyrene-divinylbenzene beads (PS-DVB). These polymers are useful for the for selective removal and recovery of environmentally and economically important metal ions from aqueous solution, as a function of pH. The Fe.sup.3+ ion selectivity shown for PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads in competition with a similar concentration of Cu.sup.2+, Zn.sup.2+, Mn.sup.2+, Ni.sup.2+,Mg.sup.2+, Al.sup.3+, and Cr.sup.3+ ions at pH 1-3. Further, the metal ion selectivity is changed at higher pH values in the absence of Fe.sup.3+ (for example, Hg.sup.2+ at pH 3). The rates of selective removal and recovery of the trivalent metal ions, e.g. Fe.sup.3+ Al.sup.3+ ion etc. with the PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads use determined are useful as well as equilibrium selectivity coefficient (K.sub.m) values for all metal competition studies. The chelate effect for the predisposed octahedral PS-3,3-LICAMS polymer pendant ligand is the reason that this ligand has a more pronounced selectivity for Fe.sup.3+ ion in comparison to the PS-CATS polymer beads. The predisposed square planar PS-2-6-Mn.sup.2+, Ni.sup.2+, and Mg.sup.2+, than either PS-CATS or PS-3,3-LICAMS. However, Fe.sup.3+ ion still dominates in competition with other divalent and trivalent metal ions. In the absence of Fe.sup.3+, the polymer ligand is selective for Al.sup.3+, Cu.sup.2+ or Hg.sup.2+. The changing of the cavity size from two CH.sub.2 groups to six CH.sub.2 groups in the PS-2-6-LICAMS polymer pendant ligand series does not effect the order of metal ion selectivity.

  10. Polymer-supported sulfonated catechol and linear catechol amide ligands and their use in selective metal ion removal recovery from aqueous solutions

    DOEpatents

    Fish, R.H.

    1998-11-10

    The present invention concerns the synthesis of several biomimetically important polymer-supported, sulfonated catechol (PS-CATS), sulfonated bis-catechol linear amide (PS-2-6-LICAMS) and sulfonated 3,3-linear tris-catechol amide (PS-3,3-LICAMS) ligands, which chemically bond to modified 6% crosslinked macroporous polystyrene-divinylbenzene beads (PS-DVB). These polymers are useful for the for selective removal and recovery of environmentally and economically important metal ions from aqueous solution, as a function of pH. The Fe{sup 3+} ion selectivity shown for PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads in competition with a similar concentration of Cu{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, Ni{sup 2+}, Mg{sup 2+}, Al{sup 3+}, and Cr{sup 3+} ions at pH 1--3. Further, the metal ion selectivity is changed at higher pH values in the absence of Fe{sup 3+} (for example, Hg{sup 2+} at pH 3). The rates of selective removal and recovery of the trivalent metal ions, e.g. Fe{sup 3+}, Al{sup 3+} ion etc. with the PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads used determined are useful as well as equilibrium selectivity coefficient (K{sub m}) values for all metal competition studies. The chelate effect for the predisposed octahedral PS-3,3-LICAMS polymer pendant ligand is the reason that this ligand has a more pronounced selectivity for Fe{sup 3+} ion in comparison to the PS-CATS polymer beads. The predisposed square planar PS-2,6-LICAMS series of polymer pendant ligands are more selective to divalent metal ions Cu{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, Ni{sup 2+}, and Mg{sup 2+}, than either PS-CATS or PS-3,3-LICAMS. However, Fe{sup 3+} ion still dominates in competition with other divalent and trivalent metal ions. In the absence of Fe{sup 3+}, the polymer ligand is selective for Al{sup 3+}, Cu{sup 2+} or Hg{sup 2+}. The changing of the cavity size from two CH{sub 2} groups to six CH{sub 2} groups in the PS-2-6-LICAMS polymer pendant ligand series does not effect

  11. Polymer-supported sulfonated catechol and linear catechol amide ligands and their use in selective metal ion removal and recovery from aqueous solutions

    DOEpatents

    Fish, R.H.

    1997-04-22

    The present invention concerns the synthesis of several biomimetically important polymer-supported, sulfonated catechol (PS-CATS), sulfonated bis-catechol linear amide (PS-2-6-LICAMS) and sulfonated 3,3-linear tris-catechol amide (PS-3,3-LICAMS) ligands, which chemically bond to modified 6% crosslinked macroporous polystyrene-divinylbenzene beads (PS-DVB). These polymers are useful for the for selective removal and recovery of environmentally and economically important metal ions from aqueous solution, as a function of pH. The Fe{sup 3+} ion selectivity shown for PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads in competition with a similar concentration of Cu{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, Ni{sup 2+}, Mg{sup 2+}, Al{sup 3+}, and Cr{sup 3+} ions at pH 1--3. Further, the metal ion selectivity is changed at higher pH values in the absence of Fe{sup 3+} (for example, Hg{sup 2+} at pH 3). The rates of selective removal and recovery of the trivalent metal ions, e.g. Fe{sup 3+}, Al{sup 3+} ion etc. with the PS-CATS, PS-2-6-LICAMS, and PS-3,3-LICAMS polymer beads use determined are useful as well as equilibrium selectivity coefficient (K{sub m}) values for all metal competition studies. The chelate effect for the predisposed octahedral PS-3,3-LICAMS polymer pendant ligand is the reason that this ligand has a more pronounced selectivity for Fe{sup 3+} ion in comparison to the PS-CATS polymer beads. The predisposed square planar PS-2-6-Mn{sup 2+}, Ni{sup 2+}, and Mg{sup 2+}, than either PS-CATS or PS-3,3-LICAMS. However, Fe{sup 3+} ion still dominates in competition with other divalent and trivalent metal ions. In the absence of Fe{sup 3+}, the polymer ligand is selective for Al{sup 3+}, Cu{sup 2+} or Hg{sup 2+}. The changing of the cavity size from two CH{sub 2} groups to six CH{sub 2} groups in the PS-2-6-LICAMS polymer pendant ligand series does not effect the order of metal ion selectivity. 9 figs.

  12. Catechol-Functionalized Synthetic Polymer as a Dental Adhesive to Contaminated Dentin Surface for a Composite Restoration.

    PubMed

    Lee, Sang-Bae; González-Cabezas, Carlos; Kim, Kwang-Mahn; Kim, Kyoung-Nam; Kuroda, Kenichi

    2015-08-10

    This study reports a synthetic polymer functionalized with catechol groups as dental adhesives. We hypothesize that a catechol-functionalized polymer functions as a dental adhesive for wet dentin surfaces, potentially eliminating the complications associated with saliva contamination. We prepared a random copolymer containing catechol and methoxyethyl groups in the side chains. The mechanical and adhesive properties of the polymer to dentin surface in the presence of water and salivary components were determined. It was found that the new polymer combined with an Fe(3+) additive improved bond strength of a commercial dental adhesive to artificial saliva contaminated dentin surface as compared to a control sample without the polymer. Histological analysis of the bonding structures showed no leakage pattern, probably due to the formation of Fe-catechol complexes, which reinforce the bonding structures. Cytotoxicity test showed that the polymers did not inhibit human gingival fibroblast cells proliferation. Results from this study suggest a potential to reduce failure of dental restorations due to saliva contamination using catechol-functionalized polymers as dental adhesives.

  13. Catechol-Functionalized Synthetic Polymer as a Dental Adhesive to Contaminated Dentin Surface for a Composite Restoration

    PubMed Central

    2015-01-01

    This study reports a synthetic polymer functionalized with catechol groups as dental adhesives. We hypothesize that a catechol-functionalized polymer functions as a dental adhesive for wet dentin surfaces, potentially eliminating the complications associated with saliva contamination. We prepared a random copolymer containing catechol and methoxyethyl groups in the side chains. The mechanical and adhesive properties of the polymer to dentin surface in the presence of water and salivary components were determined. It was found that the new polymer combined with an Fe3+ additive improved bond strength of a commercial dental adhesive to artificial saliva contaminated dentin surface as compared to a control sample without the polymer. Histological analysis of the bonding structures showed no leakage pattern, probably due to the formation of Fe–catechol complexes, which reinforce the bonding structures. Cytotoxicity test showed that the polymers did not inhibit human gingival fibroblast cells proliferation. Results from this study suggest a potential to reduce failure of dental restorations due to saliva contamination using catechol-functionalized polymers as dental adhesives. PMID:26176305

  14. Effect of an allophanic soil on humification reactions between catechol and glycine: Spectroscopic investigations of reaction products

    NASA Astrophysics Data System (ADS)

    Fukushima, Masami; Miura, Akitaka; Sasaki, Masahide; Izumo, Kenji

    2009-01-01

    Adduction of amino acids to phenols is a possible humification reaction pathway [F.J. Stevenson, Humus Chemistry: Genesis, Composition, Reaction, second ed., Wiley, New York, 1994, pp. 188-211; M.C. Wang, P.M. Huang, Sci. Total Environ. 62 (1987) 435; M.C. Wang, P.M. Huang, Soil Sci. Soc. Am. J. 55 (1991) 1156; M.C. Wang, P.M. Huang, Geoderma 112 (2003) 31; M.C. Wang, P.M. Huang, Geoderma 124 (2005) 415]. To elucidate the reaction kinetics and products of abiotic humification, the effects of an allophanic soil on the adduction of amino acids to phenols were investigated using catechol (CT) and glycine (Gly) as a model phenol and amino acid, respectively. An aqueous solution containing CT and Gly (pH 7.0) in the presence of allophanic soil was incubated for 2 weeks, and the kinetics of the humification reactions were monitored by analysis of absorptivity at 600 nm ( E600). A mixture of CT and Gly in the absence of allophanic soil was used as a control. The E600 value increased markedly in the presence of allophanic soil. In addition, unreacted CT was detected in the control reaction mixture, but not in the allophane-containing reaction mixture. Under the sterilized conditions, absorbance at 600 nm for the control reaction mixture was significantly smaller than that for the allophanic soil-containing reaction mixture, which indicates there was no microbial participation during incubation. These results indicate that the allophanic soil effectively facilitated humification reactions between CT and Gly. The reaction mixtures were acidified and humic-like acid (HLA) was isolated as a precipitate. The elemental composition, acidic functional group contents, molecular weight, FT-IR, solid-state CP-MAS 13C NMR, and 1H NMR spectra of the purified HLAs were analyzed. The results of these analyses indicate that the nitrogen atom of Gly binds to the aromatic carbon of CT in the HLA products.

  15. A novel catechol-based universal support for oligonucleotide synthesis.

    PubMed

    Anderson, Keith M; Jaquinod, Laurent; Jensen, Michael A; Ngo, Nam; Davis, Ronald W

    2007-12-21

    A novel universal support for deoxyribo- and ribonucleic acid synthesis has been developed. The support, constructed from 1,4-dimethoxycatechol, represents an improvement over existing universal supports because of its ability to cleave and deprotect under mild conditions in standard reagents. Because no nonvolatile additives are required for cleavage and deprotection, the synthesized oligonucleotides do not require purification prior to use in biochemical assays. Using reverse phase HPLC and electrospray mass spectroscopy, it was determined that oligonucleotides synthesized on the universal support (UL1) 3'-dephosphorylate quickly (9 h in 28-30% ammonium hydroxide (NH4OH) at 55 degrees C, 2 h in 28-30% NH4OH at 80 degrees C, or <1 h in ammonium hydroxide/methylamine (1:1) (AMA) at 80 degrees C). Oligonucleotides used as primers for the polymerase chain reaction (PCR) assay were found to perform identically to control primers, demonstrating full biological compatibility. In addition, a method was developed for sintering the universal support directly into a filter plug which can be pressure fit into the synthesis column of a commercial synthesizer. The universal support plugs allow the synthesis of high-quality oligonucleotides at least 120 nucleotides in length, with purity comparable to non-universal commercial supports and approximately 50% lower reagent consumption. The universal support plugs are routinely used to synthesize deoxyribo-, ribo-, 3'-modified, 5'-modified, and thioated oligonucleotides. The flexibility of the universal support and the efficiency of 3'-dephosphorylation are expected to increase the use of universal supports in oligonucleotide synthesis.

  16. Quaternary ammonium functionalized clay film electrodes modified with polyphenol oxidase for the sensitive detection of catechol.

    PubMed

    Mbouguen, Justin Kemmegne; Ngameni, Emmanuel; Walcarius, Alain

    2007-09-30

    Naturally occurring Cameroonian smectite clay has been grafted with trimethylpropylammonium (TMPA) groups and the resulting organoclay has been deposited onto a glassy carbon electrode surface as a suitable immobilization matrix for polyphenol oxidase (PPO). High sensitivity of the electrochemical device to catechol biosensing can be achieved when the enzyme was impregnated within the organoclay film subsequent to its deposition due to favorable electrostatic interaction between PPO and the TMPA-clay layer. The bioelectrode preparation method was also compatible with the use of a mediator (i.e., ferrocene) and the best performance was obtained with a three-layer configuration made of glassy carbon coated with a first layer of ferrocene (Fc), which was then covered with the PPO-impregnated TMPA-clay layer, and finally overcoated with an enzyme-free TMPA-clay film acting as a protecting overlayer to avoid leaching of the biomolecule in solution. The electrochemical behavior of the modified film electrodes was first characterized by cyclic voltammetry and, then, they were evaluated for the amperometric biosensing of the model analyte catechol in batch conditions and in flow injection analysis. Various experimental parameters likely to influence the biosensor response have been investigated, including the electrode preparation mode (composition configuration, thickness), the usefulness of a mediator, the operating potential and pH of the medium, as well as the advantageous features of the TMPA-clay in comparison to related film electrodes based on non-functionalized clays. The organoclay was found to provide a favorable environment to enzyme activity and the multilayer configuration of the film electrode to provide a biosensor with good characteristics, such as an extended linear range for catechol detection (2 x 10(-8) to 1.2 x 10(-5)M) and a detection limit in the nanomolar range (9 x 10(-9)M). PMID:17537626

  17. Phorbol myristate acetate and catechol as skin cocarcinogens in SENCAR mice

    SciTech Connect

    Van Duuren, B.L.; Melchionne, S.; Seidman, I.

    1986-09-01

    The enhancement of the carcinogenicity of benzo(a) pyrene (B(a)P) and ..beta..-propiolactone (BPL) by the mouse skin cocarcinogens phorbol myristate acetate (PMA) and catechol were examined in female SENCAR mice, 30 per group. The carcinogen and cocarcinogen were applied simultaneously, three times weekly for 490-560 days. B(a)P and BPL were used at constant doses of 5 and 50 ..mu..g, respectively, in all experiments. PMA was used at three doses, 2.5, 1.0, and 0.5 ..mu..g per application, and catechol was used at one dose, 2 mg per application. Control groups included animals that received carcinogen only, cocarcinogen only, acetone only, and no treatment. The carcinogenicity of B(a)P and BPL were enhanced by the cocarcinogens, particularly in terms of tumor multiplicity. For both carcinogens, the most marked cocarcinogenic effects were observed at the lowest dose of PMA used (0.5 ..mu..g per application). This observation applied for days to first tumor, animals with tumors, tumor multiplicity, and incidence of malignant skin tumors. Catechol applied alone did not induce any tumors; with PMA alone there were significant incidences of benign and malignant tumors, e.g., at a dose of only 0.5 ..mu..g per application, 15 of 30 animals had 28 tumors, 5 of which were squamous carcinomas. In two-stage carcinogenesis experiments with 7,12-dimethylbenz(a)anthracene (DMBA) as initiator and PMA as promoter, SENCAR mice showed a greater susceptibility to tumor induction when compared to ICR/Ha mice used in earlier work. This susceptibility was most notable in terms of rate of tumor appearance and tumor multiplicity.

  18. Benzene and dopamine catechol quinones could initiate cancer or neurogenic disease.

    PubMed

    Zahid, Muhammad; Saeed, Muhammad; Rogan, Eleanor G; Cavalieri, Ercole L

    2010-01-15

    Catechol quinones of estrogens react with DNA by 1,4-Michael addition to form depurinating N3Ade and N7Gua adducts. Loss of these adducts from DNA creates apurinic sites that can generate mutations leading to cancer initiation. We compared the reactions of the catechol quinones of the leukemogenic benzene (CAT-Q) and N-acetyldopamine (NADA-Q) with 2'-deoxyguanosine (dG) or DNA. NADA was used to prevent intramolecular cyclization of dopamine quinone. Reaction of CAT-Q or NADA-Q with dG at pH 4 afforded CAT-4-N7dG or NADA-6-N7dG, which lost deoxyribose with a half-life of 3 h to form CAT-4-N7Gua or 4 h to form NADA-6-N7Gua. When CAT-Q or NADA-Q was reacted with DNA, N3Ade adducts were formed and lost from DNA instantaneously, whereas N7Gua adducts were lost over several hours. The maximum yield of adducts in the reaction of CAT-Q or NADA-Q with DNA at pH 4 to 7 was at pH 4. When tyrosinase-activated CAT or NADA was reacted with DNA at pH 5 to 8, adduct levels were much higher (10- to 15-fold), and the highest yield was at pH 5. Reaction of catechol quinones of natural and synthetic estrogens, benzene, naphthalene, and dopamine with DNA to form depurinating adducts is a common feature that may lead to initiation of cancer or neurodegenerative disease.

  19. Dioxygenase- and monooxygenase-catalysed synthesis of cis-dihydrodiols, catechols, epoxides and other oxygenated products.

    PubMed

    Nolan, Louise C; O'Connor, Kevin E

    2008-11-01

    Oxidoreductases are an emerging class of biotechnologically relevant enzymes due to their regio- and stereo-specificity. The selective oxygenation of aromatic compounds by oxidoreductases has received much attention and a wide range of reactions have been documented using these enzymes from various microbial sources. This review gives an overview of various dioxygenase, monooxygenase and oxidase enzymes that have been manipulated for the synthesis of products such as cis-dihydrodiols, catechols, epoxides and other oxygenated products. The use of protein engineering and its advancement in the synthesis of recombinant enzymes is also discussed.

  20. Physico-chemical characterization of SOA derived from catechol and guaiacol - a model substance for the aromatic fraction of atmospheric HULIS

    NASA Astrophysics Data System (ADS)

    Ofner, J.; Krüger, H.-U.; Grothe, H.; Schmitt-Kopplin, P.; Whitmore, K.; Zetzsch, C.

    2011-01-01

    Secondary organic aerosol (SOA) was produced from the aromatic precursors catechol and guaiacol by reaction with ozone in the presence and absence of simulated sunlight and humidity and investigated for its properties as a proxy for HUmic-LIke Substances (HULIS). Beside a small particle size, a relatively low molecular weight and typical optical features in the UV/VIS spectral range, HULIS contain a typical aromatic and/or olefinic chemical structure and highly oxidized functional groups within a high chemical diversity. Various methods were used to characterize the secondary organic aerosols obtained: Fourier transform infrared spectroscopy (FTIR) demonstrated the formation of several carbonyl containing functional groups as well as structural and functional differences between aerosols formed at different environmental conditions. UV/VIS spectroscopy of filter samples showed that the particulate matter absorbs far into the visible range up to more than 500 nm. Ultrahigh resolved mass spectroscopy (ICR-FT/MS) determined O/C-ratios between 0.3 and 1 and observed m/z ratios between 200 and 450 to be most abundant. Temperature-programmed-pyrolysis mass spectroscopy (TPP-MS) identified carboxylic acids and lactones/esters as major functional groups. Particle sizing using a condensation-nucleus-counter and differential-mobility-particle-sizer (CNC/DMPS) monitored the formation of small particles during the SOA formation process. Particle imaging, using field-emission-gun scanning electron microscopy (FEG-SEM), showed spherical particles, forming clusters and chains. We conclude that catechol and guaiacol are appropriate precursors for studies of the processing of aromatic SOA with atmospheric HULIS properties on the laboratory scale.

  1. New functional model complexes of intradiol-cleaving catechol dioxygenases: properties and reactivity of CuII(L)(O2Ncat).

    PubMed

    Kaizer, József; Zsigmond, Zoltán; Ganszky, Ildikó; Speier, Gábor; Giorgi, Michel; Réglier, Marius

    2007-05-28

    Complexes Cu(O2Ncat)(tbeda) (1) and Cu(O2Ncat)(tmeda) (2) (tbeda = N,N,N',N'-tetrabenzylethylenediamine, tmeda=N,N,N',N'-tetramethylethylenenediamine, O2NcatH2=4-nitrocatechol) have been prepared by the reaction of copper(II) perchlorate with 4-nitrocatechol in the presence of triethylamine and the appropriate bidentate ligand. These compounds represent structural and functional model systems for the copper-containing catechol 1,2-dioxygenase. Both complexes have been structurally characterized by X-ray crystallography and by UV-vis, IR, and EPR spectroscopies. Upon protonation of 1 and 2 with perchloric acid, the bidentate coordination of O2Ncat could be reversible converted to the monodentate coordination of O2NcatH. The equilibrium constants were found to be 4200 and 3500, respectively, by measuring the UV-vis spectra in DMF. Back-titration with morpholine proved the reversibility of both reactions. Kinetic data on the oxygenation of 1 and 2 revealed overall second-order rate equations with kinetic parameters: ktbeda=(4.63+/-0.23)x10(-2) mol-1 dm3 s-1, DeltaH=51+/-6 kJ mol-1, DeltaS=-137+/-16 J mol-1 K-1; ktmeda=(0.89+/-0.23) mol-1 dm3 s-1, DeltaH=85+/-7 kJ mol-1, DeltaS=-57+/-19 J mol-1 K-1 at 365.16 K. Oxygenation of 1, 2, and [Cu(O2NcatH)(L)]ClO4 (L=tbeda, tmeda) in DMF solution at ambient conditions gives the corresponding intradiol ring-cleaved (2-nitro-muconato)copper(II) complexes. These data support the assumption that the reaction of the differently coordinated catecholate ligand with dioxygen shows only 1,2-dioxygenase activity.

  2. Crystallization and preliminary crystallographic characterization of catechol-O-methyltransferase in complex with its cosubstrate and an inhibitor.

    PubMed

    Rodrigues, M L; Archer, M; Bonifácio, M J; Soares-da-Silva, P; Carrondo, M A

    2001-06-01

    Catechol-O-methyltransferase (COMT) is involved in the metabolism of catecholamines, catechol steroids and xenobiotic catechols. A precise knowledge of the enzyme-inhibitor structural interactions could help in the design of better inhibitors. Soluble rat COMT was expressed in Escherichia coli and the recombinant protein was crystallized with a new tight-binding inhibitor, BIA 3-335 [1-(3,4-dihydroxy-5-nitrophenyl)-3-(n-3'-trifluoromethylphenyl)piperazine-1-propanone dihydrochloride]. The crystals were obtained by the sitting-drop vapour-diffusion method using PEG 6K as a precipitant. These crystals diffracted to better than 1.9 A and belong to the trigonal space group P3(2)21. The unit-cell parameters for the crystal measured at room temperature were a = b = 51.5, c = 168.3 A; each shrank by about 1 A on freezing. PMID:11375525

  3. Experimental and computational evidence for the mechanism of intradiol catechol dioxygenation by non-heme iron(III) complexes.

    PubMed

    Jastrzebski, Robin; Quesne, Matthew G; Weckhuysen, Bert M; de Visser, Sam P; Bruijnincx, Pieter C A

    2014-11-24

    Catechol intradiol dioxygenation is a unique reaction catalyzed by iron-dependent enzymes and non-heme iron(III) complexes. The mechanism by which these systems activate dioxygen in this important metabolic process remains controversial. Using a combination of kinetic measurements and computational modelling of multiple iron(III) catecholato complexes, we have elucidated the catechol cleavage mechanism and show that oxygen binds the iron center by partial dissociation of the substrate from the iron complex. The iron(III) superoxide complex that is formed subsequently attacks the carbon atom of the substrate by a rate-determining C-O bond formation step. PMID:25322920

  4. Catechol-based layer-by-layer assembly of composite coatings: a versatile platform to hierarchical nano-materials.

    PubMed

    Wang, C X; Braendle, A; Menyo, M S; Pester, C W; Perl, E E; Arias, I; Hawker, C J; Klinger, D

    2015-08-21

    Inspired by the marine mussel's ability to adhere to surfaces underwater, an aqueous catechol-based dip coating platform was developed. Using a catechol-functionalized polyacrylamide binder in combination with inorganic nanoparticles enables the facile fabrication of robust composite coatings via a layer-by-layer process. This modular assembly of well-defined building blocks provides a versatile alternative to electrostatic driven approaches with layer thickness and refractive indices being readily tunable. The platform nature of this approach enables the fabrication of hierarchically ordered nano-materials such as Bragg stacks.

  5. Application of p-toluidine in chromogenic detection of catechol and protocatechuate, diphenolic intermediates in catabolism of aromatic compounds

    SciTech Connect

    Parke, D. )

    1992-08-01

    In the presence of p-toluidine and iron, protocatechuate and catechols yield color. Inclusion of p-toluidine in media facilities the screening of microbial strains for alterations affecting aromatic catabolism. Such strains include mutants affected in the expression of oxygenases and Escherichia coli colonies carrying cloned or subcloned aromatic catabolic genes which encode enzymes giving rise to protocatechuate or catechol. The diphenolic detection system can also be applied to the creation of vectors relying on insertion of cloned DNA into one of the latter marker genes.

  6. Mechanics of metal-catecholate complexes: The roles of coordination state and metal types

    PubMed Central

    Xu, Zhiping

    2013-01-01

    There have been growing evidences for the critical roles of metal-coordination complexes in defining structural and mechanical properties of unmineralized biological materials, including hardness, toughness, and abrasion resistance. Their dynamic (e.g. pH-responsive, self-healable, reversible) properties inspire promising applications of synthetic materials following this concept. However, mechanics of these coordination crosslinks, which lays the ground for predictive and rational material design, has not yet been well addressed. Here we present a first-principles study of representative coordination complexes between metals and catechols. The results show that these crosslinks offer stiffness and strength near a covalent bond, which strongly depend on the coordination state and type of metals. This dependence is discussed by analyzing the nature of bonding between metals and catechols. The responsive mechanics of metal-coordination is further mapped from the single-molecule level to a networked material. The results presented here provide fundamental understanding and principles for material selection in metal-coordination-based applications. PMID:24107799

  7. Crystal structures of the apo and holo form of rat catechol-O-methyltransferase.

    PubMed

    Tsuji, Eiichi; Okazaki, Kosuke; Isaji, Masayuki; Takeda, Kei

    2009-03-01

    Catechol-O-methyltransferase (COMT, EC 2.1.1.6) is a monomeric enzyme that catalyzes the transfer of a methyl group from S-adenosyl-l-methionine (AdoMet) to the phenolic oxygen of substituted catechols. Although the inhibitor recognition pattern and AdoMet site have already been studied crystallographically, structural information on the catalytic cycle of COMT has not yet been obtained. In this study, comparison of the co-factor and inhibitor-bound structures revealed that the Apo form of COMT shows a conformational change and there was no cleft corresponding to the AdoMet-binding site; the overall structure was partially open form and the substrate recognition site was not clearly defined. The Holo form of COMT was similar to the quaternary structure except for the beta6-beta7 and alpha2-alpha3 ligand recognition loops. These conformational changes provide a deeper insight into the structural events occurring in reactions catalyzed by AdoMet.

  8. Facile fabrication of gold nanoparticle on zein ultrafine fibers and their application for catechol biosensor

    NASA Astrophysics Data System (ADS)

    Chen, Xiaodong; Li, Dawei; Li, Guohui; Luo, Lei; Ullah, Naseeb; Wei, Qufu; Huang, Fenglin

    2015-02-01

    A novel laccase biosensor based on a new composite of laccase-gold nanoparticles (Au NPs)-crosslinked zein ultrafine fibers (CZUF) has been fabricated for catechol determination in real solution samples. Firstly, crosslinked zein ultrafine fibers containing gold nanoparticles (A-CZUF) were prepared by combining electrospinning and one-step reduction method using poly(ethyleneimine) (PEI) as reducing and crosslinking agent. A smooth morphology and relative average distribution of A-CZUF were depicted by scanning electron microscope (SEM) and transmission electron microscopy (TEM). The Fourier transform infrared spectroscopy (FT-IR) analysis indicated that PEI molecules attached to the surface of the zein ultrafine fibers via the reaction of functional groups between PEI and glyoxal. The results obtained from ultraviolet visible spectroscopy (UV-vis spectroscopy), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA) for A-CZUF confirmed the existence of Au NPS coated on the surface of CZUF. Square wave voltammetry (SWV) and cyclic voltammetry (CV) were used to detect the electrochemical performance of the proposed biosensor. The results demonstrated that this biosensor possessed a high sensitive detection to catechol, which was attributed to the direct electron transfer (DET) facilitated by Au NPs and high catalytic ability obtained from laccase. In addition, the proposed biosensor exhibited good reproducibility, stability and selectivity.

  9. Oxidative degradation and associated mineralization of catechol, hydroquinone and resorcinol catalyzed by birnessite.

    PubMed

    Chang Chien, S W; Chen, H L; Wang, M C; Seshaiah, K

    2009-02-01

    Abiotic degradation and mineralization of catechol, hydroquinone, and resorcinol catalyzed by birnessite (delta-MnO2) was investigated. Studies were carried out by monitoring changes of pE versus time and pH versus time of the reaction systems during the initial 10 h reaction period and release of CO2 and associated reactions at the end of a 90 h reaction period. The reactions under anoxic condition were compared with aeration condition. The reactions were carried out in suspensions at initial pH of 6.0 under air and N2 atmosphere at room temperature and free of microbial activity. These results indicated that kinetic-related changes of pE versus time and pH versus time were dependent on structural characteristics of phenolic compound and aeration or anoxic condition in the reaction system. The sequence of the mineralization of phenolic compounds catalyzed by delta-MnO2 in presence of air expressed by CO2 release was catechol > hydroquinone > or = resorcinol and the differences were significant. However, under an N2 atmosphere the amounts of CO2 released were drastically reduced with insignificant differences among the three reaction systems. Further, phenolic compound degradations, dissolved and adsorbed Mn, and oxidation state of Mn in delta-MnO2 were also determined to elucidate the catalytic efficacy mediated by both O2 and delta-MnO2 in the reaction systems.

  10. Mechanics of metal-catecholate complexes: the roles of coordination state and metal types.

    PubMed

    Xu, Zhiping

    2013-10-10

    There have been growing evidences for the critical roles of metal-coordination complexes in defining structural and mechanical properties of unmineralized biological materials, including hardness, toughness, and abrasion resistance. Their dynamic (e.g. pH-responsive, self-healable, reversible) properties inspire promising applications of synthetic materials following this concept. However, mechanics of these coordination crosslinks, which lays the ground for predictive and rational material design, has not yet been well addressed. Here we present a first-principles study of representative coordination complexes between metals and catechols. The results show that these crosslinks offer stiffness and strength near a covalent bond, which strongly depend on the coordination state and type of metals. This dependence is discussed by analyzing the nature of bonding between metals and catechols. The responsive mechanics of metal-coordination is further mapped from the single-molecule level to a networked material. The results presented here provide fundamental understanding and principles for material selection in metal-coordination-based applications.

  11. Bio-inspired multifunctional catecholic assembly for photo-programmable biointerface.

    PubMed

    Huang, Chun-Jen; Wang, Lin-Chuan

    2015-10-01

    This article reports a novel multifunctional mussel-inspired zwitterionic catecholic assembly to form a photoresponsive biointerface. The assembly is the combination of the antifouling sulfobetaine and photocleavable o-nitrophenyl moieties into a molecule, becoming sulfobetaine nitrodopamine (SB-nDA). We demonstrated the formation of a compact thin SB-nDA film on TiO₂ by using the pH transition approach. The film thickness, surface wettability and elemental composition were characterized using ellipsometry, contact angle goniometer, atomic force microscopy and X-ray photoelectron spectroscopy, respectively. The SB-nDA thin films can effectively resist adhesion of both Gram-positive Staphylococcus epidermidis and Gram-negative Pseudomonas aeruginosa by more than 95% relative to bare TiO₂. Quartz crystal microbalance with dissipation (QCM-D) sensor was employed for protein fouling tests, showing the comparable antifouling property of SB-nDA with thiol- or silane-based surface ligands. More importantly, the spatiotemporal control over the bioinertness by UV irradiation has been studied with bacterial and protein adsorption. Therefore, the catecholic chemistry can be used for programmable tailoring of interfacial properties, permitting potential application in light-guided targeting for nanomedicine. PMID:26208296

  12. Phenolic compounds and fatty acid composition of organic and conventional grown pecan kernels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study, differences in contents of phenolic compounds and fatty acids in pecan kernels of organically versus conventionally grown pecan cultivars (‘Desirable’, ‘Cheyenne’, and ‘Wichita’) were evaluated. Although we were able to identify nine phenolic compounds (gallic acid, catechol, catechin...

  13. Bio-inspired catechol chemistry: a new way to develop a re-moldable and injectable coacervate hydrogel.

    PubMed

    Oh, Yeon Jeong; Cho, Il Hwan; Lee, Haeshin; Park, Ki-Jung; Lee, Hyukjin; Park, Sung Young

    2012-12-18

    A new way is demonstrated to develop a bio-inspired coacervate hydrogel by following catechol chemistry showing injectable and re-moldable physical properties. The formed coacervate shows potential long-term stability under water. Depending on pH, formation of the coacervate has been verified which is confirmed by XPS and zeta potential measurements.

  14. Mesoporous carbon nitride based biosensor for highly sensitive and selective analysis of phenol and catechol in compost bioremediation.

    PubMed

    Zhou, Yaoyu; Tang, Lin; Zeng, Guangming; Chen, Jun; Cai, Ye; Zhang, Yi; Yang, Guide; Liu, Yuanyuan; Zhang, Chen; Tang, Wangwang

    2014-11-15

    Herein, we reported here a promising biosensor by taking advantage of the unique ordered mesoporous carbon nitride material (MCN) to convert the recognition information into a detectable signal with enzyme firstly, which could realize the sensitive, especially, selective detection of catechol and phenol in compost bioremediation samples. The mechanism including the MCN based on electrochemical, biosensor assembly, enzyme immobilization, and enzyme kinetics (elucidating the lower detection limit, different linear range and sensitivity) was discussed in detail. Under optimal conditions, GCE/MCN/Tyr biosensor was evaluated by chronoamperometry measurements and the reduction current of phenol and catechol was proportional to their concentration in the range of 5.00 × 10(-8)-9.50 × 10(-6)M and 5.00 × 10(-8)-1.25 × 10(-5)M with a correlation coefficient of 0.9991 and 0.9881, respectively. The detection limits of catechol and phenol were 10.24 nM and 15.00 nM (S/N=3), respectively. Besides, the data obtained from interference experiments indicated that the biosensor had good specificity. All the results showed that this material is suitable for load enzyme and applied to the biosensor due to the proposed biosensor exhibited improved analytical performances in terms of the detection limit and specificity, provided a powerful tool for rapid, sensitive, especially, selective monitoring of catechol and phenol simultaneously. Moreover, the obtained results may open the way to other MCN-enzyme applications in the environmental field.

  15. VISCOSITY AND BINDER COMPOSITION EFFECTS ON TYROSINASE-BASED CARBON PASTE ELECTRODE FOR DETECTION OF PHENOL AND CATECHOL

    EPA Science Inventory

    The systematic study of the effect of binder viscosity on the sensitivity of a tyrosinase-based carbon paste electrode (CPE) biosensor for phenol and catechol is reported. Silicon oil binders with similar (polydimethylsiloxane) chemical composition were used to represent a wid...

  16. Laccase immobilized on a PAN/adsorbents composite nanofibrous membrane for catechol treatment by a biocatalysis/adsorption process.

    PubMed

    Wang, Qingqing; Cui, Jing; Li, Guohui; Zhang, Jinning; Li, Dawei; Huang, Fenglin; Wei, Qufu

    2014-03-19

    The treatment of catechol via biocatalysis and adsorption with a commercial laccase immobilized on polyacrylonitrile/montmorillonite/graphene oxide (PAN/MMT/GO) composite nanofibers was evaluated with a homemade nanofibrous membrane reactor. The properties in this process of the immobilized laccase on PAN, PAN/MMT as well as PAN/MMT/GO with different weight ratios of MMT and GO were investigated. These membranes were successfully applied for removal of catechol from an aqueous solution. Scanning electron microscope images revealed different morphologies of the enzyme aggregates on different supports. After incorporation of MMT or MMT/GO, the optimum pH showed an alkaline shift to 4, compared to 3.5 for laccase immobilized on pure PAN nanofibers. The optimum temperature was at 55 °C for all the immobilized enzymes. Besides, the addition of GO improved the operational stability and storage stability. A 39% ± 2.23% chemical oxygen demand (COD) removal from the catechol aqueous solution was achieved. Experimental results suggested that laccase, PAN, adsorbent nanoparticles (MMT/GO) can be combined together for catechol treatment in industrial applications.

  17. RATE AND CAPACITY OF HEPATIC MICROSOMAL RING HYDROXYLATION OF PHENOL TO HYDROQUINONE AND CATECHOL IN RAINBOW TROUT (ONCORHYNCHUS MYKISS)

    EPA Science Inventory

    Rainbow trout liver microsomes were used to study the rate of ring-hydroxylation of phenol (PH) by directly measuring the production of hydroquinone (HQ), the primary metabolite, and catechol (CAT), a secondary metabolite. An HPLC method with integrated ultroviolet (UV) and elect...

  18. RATE AND CAPACITY OF HEPATIC MICROSOMAL RING HYDROXYLATION OF PHENOL TO HYDROQUINONE AND CATECHOL IN RAINBOW TROUT

    EPA Science Inventory

    Rainbow trout (Oncorhynchus mykiss) liver microsomes were used to study the rate of ring-hydroxylation of phenol PH) by directly measuring the production of hydroquinone (HQ), the primary metabolite, and catechol (CAT), a secondary metabolite. An HPLC method with integrated ultra...

  19. Susceptibility of Pseudomonas aeruginosa to catechol-substituted cephalosporin is unrelated to the pyochelin-Fe transporter FptA.

    PubMed

    Hoegy, Françoise; Gwynn, Michael N; Schalk, Isabelle J

    2010-05-01

    Previously it has been postulated that the pyochelin-Fe outer membrane transporter, FptA, is involved in the uptake of catechol-substituted cephalosporins in Pseudomonas aeruginosa. Iron uptake and antibacterial activity studies on different mutants showed clearly that FptA is unable to bind and transport these antibiotics. PMID:19777323

  20. Coupled redox transformations of catechol and cerium at the surface of a cerium(III) phosphate mineral

    NASA Astrophysics Data System (ADS)

    Cervini-Silva, Javiera; Gilbert, Benjamin; Fakra, Sirine; Friedlich, Stephan; Banfield, Jillian

    2008-05-01

    Highly insoluble Ce-bearing phosphate minerals form by weathering of apatite [Ca5(PO4)3.(OH,F,Cl)], and are important phosphorous repositories in soils. Although these phases can be dissolved via biologically-mediated pathways, the dissolution mechanisms are poorly understood. In this paper we report spectroscopic evidence to support coupling of redox transformations of organic carbon and cerium during the reaction of rhabdophane (CePO4·H2O) and catechol, a ubiquitous biogenic compound, at pH 5. Results show that the oxic-anoxic conditions influence the mineral dissolution behavior. Under anoxic conditions, the release of P and Ce occurs stoichiometrically. In contrast, under oxic conditions, the mineral dissolution behavior is incongruent, with dissolving Ce3+ ions oxidizing to CeO2. Reaction product analysis shows the formation of CO2, polymeric C, and oxalate and malate. The presence of more complex forms of organic carbon was also confirmed. Near edge X-ray absorption fine structure spectroscopy measurements at Ce-M4,5 and C-K absorption edges on reacted CePO4·H2O samples in the absence or presence of catechol and dissolved oxygen confirm that (1) the mineral surface converts to the oxide during this reaction, while full oxidation is limited to the near-surface region only; (2) the Ce valence remains unchanged when the reaction between CePO4·H2O and O2 but in the absence of catechol. Carbon K-edge spectra acquired from rhabdophane reacted with catechol under oxic conditions show spectral features before and after reaction that are considerably different from catechol, indicating the formation of more complex organic molecules. Decreases in intensity of characteristic catechol peaks are accompanied by the appearance of new π∗ resonances due to carbon in carboxyl (ca. 288.5 eV) and carbonyl (ca. 289.3 eV) groups, and the development of broad structure in the σ∗ region characteristic of aliphatic carbon. Evolution of the C K-edge spectra is consistent

  1. Neuronal effects of 4-t-Butylcatechol: A model for catechol-containing antioxidants

    SciTech Connect

    Lo, Y.-C. Liu Yuxin; Lin, Y.-C.; Shih, Y.-T.; Liu, C.-M.; Burka, Leo T.

    2008-04-15

    Many herbal medicines and dietary supplements sold as aids to improve memory or treat neurodegenerative diseases or have other favorable effects on the CNS contain a catechol or similar 1,2-dihydroxy aromatic moiety in their structure. As an approach to isolate and examine the neuroprotective properties of catechols, a simple catechol 4-t-Butylcatechol (TBC) has been used as a model. In this study, we investigated the effects of TBC on lipopolysaccharide (LPS)-activated microglial-induced neurotoxicity by using the in vitro model of coculture murine microglial-like cell line HAPI with the neuronal-like human neuroblastoma cell line SH-SY5Y. We also examined the effects of TBC on 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in human dopaminergic neuroblastoma SH-SY5Y cells. TBC at concentrations from 0.1-10 {mu}M had no toxic effect on HAPI cells and SH-SY5Y cells, and it inhibited LPS (100 ng/ml)-induced increases of superoxide, intracellular ROS, gp91{sup Phox}, iNOS and a decrease of HO-1 in HAPI cells. Under coculture condition, TBC significantly reduced LPS-activated microglia-induced dopaminergic SH-SY5Y cells death. Moreover, TBC (0.1-10 {mu}M) inhibited 6-OHDA-induced increases of intracellular ROS, iNOS, nNOS, and a decrease of mitochondria membrane potential, and cell death in SH-SY5Y cells. However, the neurotoxic effects of TBC (100 {mu}M) on SH-SY5Y cells were also observed including the decrease in mitochondria membrane potential and the increase in COX-2 expression and cell death. TBC-induced SH-SY5Y cell death was attenuated by pretreatment with NS-398, a selective COX-2 inhibitor. In conclusion, this study suggests that TBC might possess protective effects on inflammation- and oxidative stress-related neurodegenerative disorders. However, the high concentration of TBC might be toxic, at least in part, for increasing COX-2 expression.

  2. Crystal structures of human 108V and 108M catechol O-methyltransferase

    SciTech Connect

    Rutherford, K.; Le Trong, I.; Stenkamp, R.E.; Parson, W.W.

    2008-08-01

    Catechol O-methyltransferase (COMT) plays important roles in the metabolism of catecholamine neurotransmitters and catechol estrogens. The development of COMT inhibitors for use in the treatment of Parkinson's disease has been aided by crystallographic structures of the rat enzyme. However, the human and rat proteins have significantly different substrate specificities. Additionally, human COMT contains a common valine-methionine polymorphism at position 108. The methionine protein is less stable than the valine polymorph, resulting in decreased enzyme activity and protein levels in vivo. Here we describe the crystal structures of the 108V and 108M variants of the soluble form of human COMT bound with S-adenosylmethionine (SAM) and a substrate analog, 3,5-dinitrocatechol. The polymorphic residue 108 is located in the {alpha}5-{beta}3 loop, buried in a hydrophobic pocket {approx}16 {angstrom} from the SAM-binding site. The 108V and 108M structures are very similar overall [RMSD of C{sup {alpha}} atoms between two structures (C{sup {alpha}} RMSD) = 0.2 {angstrom}], and the active-site residues are superposable, in accord with the observation that SAM stabilizes 108M COMT. However, the methionine side chain is packed more tightly within the polymorphic site and, consequently, interacts more closely with residues A22 ({alpha}2) and R78 ({alpha}4) than does valine. These interactions of the larger methionine result in a 0.7-{angstrom} displacement in the backbone structure near residue 108, which propagates along {alpha}1 and {alpha}5 toward the SAM-binding site. Although the overall secondary structures of the human and rat proteins are very similar (C{sup {alpha}} RMSD = 0.4 {angstrom}), several nonconserved residues are present in the SAM-(I89M, I91M, C95Y) and catechol- (C173V, R201M, E202K) binding sites. The human protein also contains three additional solvent-exposed cysteine residues (C95, C173, C188) that may contribute to intermolecular disulfide bond

  3. S-adenosylmethionine-dependent protein methylation in mammalian cytosol via tyrphostin modification by catechol-O-methyltransferase.

    PubMed

    Lipson, Rebecca S; Clarke, Steven G

    2007-10-19

    It has previously been shown that incubation of mammalian cell cytosolic extracts with the protein kinase inhibitor tyrphostin A25 results in enhanced transfer of methyl groups from S-adenosyl-[methyl-3H]methionine to proteins. These findings were interpreted as demonstrating tyrphostin stimulation of a novel type of protein carboxyl methyltransferase. We find here, however, that tyrphostin A25 addition to mouse heart cytosol incubated with S-adenosyl-[methyl-3H]methionine or S-adenosyl-[methyl-14C]methionine stimulates the labeling of small molecules in addition to proteins. Base treatment of both protein and small molecule fractions releases volatile radioactivity, suggesting labile ester-like linkages of the labeled methyl group. Production of both the base-volatile product and labeled protein occurs with tyrphostins A25, A47, and A51, but not with thirteen other tyrphostin family members. These active tyrphostins all contain a catechol moiety and are good substrates for recombinant and endogenous catechol-O-methyltransferase. Inhibition of catechol-O-methyltransferase activity with tyrphostin AG1288 prevents both base-volatile product formation and protein labeling from methyl-labeled S-adenosylmethionine in heart, kidney, and liver, but not in testes or brain extracts. These results suggest that the incorporation of methyl groups into protein follows a complex pathway initiated by the methylation of select tyrphostins by endogenous catechol-O-methyltransferase. We suggest that the methylated tyrphostins are further modified in the cell extract and covalently attached to cellular proteins. The presence of endogenous catechols in cells suggests that similar reactions can also occur in vivo.

  4. Phase transfer of oleic acid stabilized rod-shaped anatase TiO2 nanocrystals

    NASA Astrophysics Data System (ADS)

    Wilkerson, Rachel J.; Elder, Theresa; Sowinksi, Olivia; Fostvedt, Jade I.; Hoefelmeyer, James D.

    2016-06-01

    Three methods were evaluated for phase transfer of oleic acid stabilized TiO2 nanorods from non-polar phase to an aqueous phase. Three alkyltrimethylammonium bromide (C6, C8, C12) surfactants were tested and compared with an amphiphilic polymer as interdigitation agents. Ligand substitutions with catechol derivatives with polar functional groups para to the -enediol were evaluated as well. The molecular surfactants were ineffective compared to the amphiphilic polymer in the interdigitation phase transfer approach. Ligand substitution with catechols proceeded efficiently with phase transfer. The ligand substitution reactions were accompanied by gas evolution, which was found to result from decarboxylation of oleic acid in alkaline aqueous conditions.

  5. Use of cloned genes of Pseudomonas TOL plasmid to effect biotransformation of benzoates to cis-dihydrodiols and catechols by Escherichia coli cells

    SciTech Connect

    Zeyer, J.; Lehrbach, P.R.; Timmis, K.N.

    1985-12-01

    DNA fragments containing the xylD and xylL genes, which specify the broad-specificity enzymes toluate-1,2-dioxygenase and 3,5-cyclohexadiene-1,2-diol-1-carboxylic acid dehydrogenase, respectively, of TOL plasmid pWW0-161 of Pseudomonas putida have previously been cloned in the pBR322 vector plasmid. In this study, Escherichia coli cells containing hybrid plasmids carrying the cloned xylD or xylDL genes quantitatively transformed /sup 14/C-ring- and /sup 14/C-carboxy-labeled benzoate to the pathway intermediates 3,5-cyclohexadiene-1,2-diol-1-carboxylic acid (cis-dihydrodiol) and catechol, respectively. Like P. putida cells, E. coli cells containing the xylD gene transformed a variety of chloro- and hydrocarbon-substituted benzoates. The toluate-1,2-dioxygenase produced in E. coli thus exhibited the broad-substrate-specificity properties of the enzyme in P. putida. Turnover rates by the enzymes in these two bacteria are compared.

  6. Histone acetyltransferase p300 promotes MKL1-mediated transactivation of catechol-O-methyltransferase gene.

    PubMed

    Liu, Zhipeng; Luo, Xuegang; Liu, Lei; Zhao, Wenwen; Guo, Shu; Guo, Yu; Wang, Nan; He, Hongpeng; Liao, Xinghua; Ma, Wenjian; Zhou, Hao; Zhang, Tongcun

    2013-12-01

    Previous studies have revealed that histone acetyltransferase p300 is recruited to the promoters of certain cardiac and smooth muscle specific genes to enhance the transactivation activity of myocardin, which is a master regulator in cardiovascular differentiation and development. Here, we found that the gene encoding catechol-O-methyltransferase (COMT), an important metabolic enzyme catalyzing the conversion of estrogen, is also a target gene of myocardin-related transcription factors (MRTFs). Megakaryoblastic leukemia 1 (MKL1, also named MRTF-A) and p300 could synergistically augment the expression of COMT gene, increase the metabolic rate of estrogen, and thus reduce the proliferation of MCF-7 breast cancer cells stimulated by estrogen. PMID:24096006

  7. New catechol derivatives of safrole and their antiproliferative activity towards breast cancer cells.

    PubMed

    Madrid Villegas, Alejandro; Espinoza Catalán, Luis; Montenegro Venegas, Iván; Villena García, Joan; Carrasco Altamirano, Héctor

    2011-06-03

    Catechols were synthesized from safrole. Nine derivatives were prepared and assessed for antiproliferative effects using different human cell lines. The in vitro growth inhibition assay was based on the sulphorhodamine dye to quantify cell viability. The derivatives 4-allylbenzene-1,2-diol (3), 4 4-[3-(acetyloxy)propyl]-1,2-phenylene diacetate (6) and 4-[3-(acetyloxy)propyl]-5-nitro-1,2-phenylene diacetate (10) showed higher cytotoxicity than the parent compound 2 in tests performed on two breast cancer cell lines (MCF-7 and MDA-MB-231). The IC₅₀ values of 40.2 ± 6.9 μM, 5.9 ± 0.8 μM and 33.8 ± 4.9 μM, respectively, were obtained without toxicity towards dermal human fibroblast (DHF cells).

  8. Enhanced biological denitrification in the cyclic rotating bed reactor with catechol as carbon source.

    PubMed

    Moussavi, Gholamreza; Jafari, Seyed Javad; Yaghmaeian, Kamyar

    2015-08-01

    The performance of CRBR in denitrification with catechol carbon source is presented. The influence of inlet nitrate concentration, hydraulic retention time (HRT), media filling ratio and rotational speed of media on the performance of CRBR was investigated. The bioreactor could denitrify over 95% of the nitrate at an inlet concentration up to 1000 mg NO3(-)/L and a short HRT as low as 18 h. The optimum media filling ratio at which the maximum denitrification was achieved in the CRBR was 30% and the contribution of media at this condition was around 36%. The optimum ratio of media filling at which the maximum denitrification was 20 rpm and the contribution of rotational speed under this condition was around 17%. According to the findings, the CRBR is a high rate bioreactor and thus serves as an appropriate technology for denitrification of wastewaters containing a high concentration of nitrate and toxic organic compounds. PMID:25898088

  9. Seawater-Assisted Self-Healing of Catechol Polymers via Hydrogen Bonding and Coordination Interactions.

    PubMed

    Li, Jincai; Ejima, Hirotaka; Yoshie, Naoko

    2016-07-27

    It is highly desirable to prevent crack formation in polymeric materials at an early stage and to extend their lifespan, particularly when repairs to these materials would be difficult for humans. Here, we designed and synthesized catechol-functionalized polymers that can self-heal in seawater through hydrogen bonding and coordination. These bioinspired acrylate polymers are originally viscous materials, but after coordination with environmentally safe, common metal cations in seawater, namely, Ca(2+) and Mg(2+), the mechanical properties of the polymers were greatly enhanced from viscous to tough, hard materials. Reduced swelling in seawater compared with deionized water owing to the higher osmotic pressure resulted in greater toughness (∼5 MPa) and self-healing efficiencies (∼80%). PMID:27377859

  10. Adsorption/electrosorption of catechol and resorcinol onto high area activated carbon cloth.

    PubMed

    Bayram, Edip; Hoda, Numan; Ayranci, Erol

    2009-09-15

    Removal of catechol and resorcinol from aqueous solutions by adsorption and electrosorption onto high area activated carbon cloth (ACC) was investigated. Kinetics of both adsorption and electrosorption were followed by in-situ UV-spectroscopic method and the data were treated according to pseudo-first-order, pseudo-second-order and intraparticle diffusion models. It was found that the adsorption and electrosorption of these compounds onto ACC follows pseudo-second-order model. pH changes during adsorption and electrosorption were followed and discussed with regard to the interaction between ACC and adsorbate molecules, utilizing the pH(pzc) value of ACC. An electrodesorption experiment was conducted to explore the possibility of regeneration of ACC. Adsorption isotherms were derived at 25 degrees C on the basis of batch analysis. The fits of experimental isotherm data to the well-known Freundlich, Langmuir and Tempkin models were examined. PMID:19345487

  11. Toughening elastomers using mussel-inspired catechol-metal coordination complexes

    NASA Astrophysics Data System (ADS)

    Filippidi, Emmanouela; Christiani, Thomas; Valentine, Megan; Waite, J. Herbert; Israelachvili, Jacob; Ahn, Kollbe

    Amorphous, covalently-linked elastomers possess excellent reversible extensibility and high failure strain compared to other materials. However, by nature, the large deformability compromises the Young's modulus and the toughness of the elastomer to low values (< 2MPa) and imparts brittle fracture. We employ the mussel-inspired strategy of iron-catechol coordination bonding creating dynamic, reversible cross-links in addition to permanent chemical cross-links in an elastomer used in ambient, dry conditions. This simple additional energy dissipative mechanism results in increased modulus and toughness without affecting the network extensibility, which is based on the covalent network. Control of the chain relaxation time scales can be further tuned using the dynamic bonds, imparting mechanical rate dependent properties to the bulk material. The quantitative understanding of the time scales associated with the chain motion versus the metal coordination may provide another simple and independent control parameter in elastomeric material design.

  12. Abiotic reduction of nitroaromatic compounds by aqueous iron(ll)-catechol complexes.

    PubMed

    Naka, Daisuke; Kim, Dongwook; Strathmann, Timothy J

    2006-05-01

    Complexation of iron(ll) by catechol and thiol ligands leads to the formation of aqueous species that are capable of reducing substituted nitroaromatic compounds (NACs) to the corresponding anilines. No reactions of NACs are observed in FelI-only or ligand-only solutions. In solutions containing FeII and tiron, a model catechol, rates of NAC reduction are heavily dependent on pH, ligand concentration, and ionic strength. Observed pseudo-first-order rate constants (k(obs)) for 4-chloronitrobenzene reduction vary by more than 6 orders of magnitude, and the variability is well described by the expression k(obs) = k(FeL2)(6-) [FeL2(6-)], where [FeL2(6-)] is the concentration of the 1:2 FeII-tiron complex and kFeL2(6-) is the bimolecular rate constant for 4-chloronitrobenzene reaction with this species. The high reactivity of this FeII species is attributed to the low standard one-electron reduction potential of the corresponding FeIII/FeII redox couple (EH0 = -0.509 V vs NHE). The relative reactivity of different NACs can be described by a linear free-energy relationship (LFER) with the one-electron reduction potentials of the NACs, EH1'(ArNO2). The experimentally derived slope of the LFER indicates that electron transfer is rate determining. These findings suggest that FeII-organic complexes may play an important, previously unrecognized, role in the reductive transformation of persistent organic contaminants.

  13. Formation and Processing of Secondary Organic Aerosol from Catechol as a Model for Atmospheric HULIS

    NASA Astrophysics Data System (ADS)

    Ofner, Johannes; Krüger, Heinz-Ulrich; Grothe, Hinrich; Zetzsch, Cornelius

    2010-05-01

    A particular fraction of the secondary organic aerosol (SOA) termed HUmic Like Substances (HULIS) attracted attention only recently in atmospheric aerosol, initiating a discourse about their aromaticity and other properties, such as reactivity and hygroscopicity. A major portion of HULIS originates from volatile organic compounds, which are formed by abiotic oxidation reactions involving mainly OH radicals, ozone, nitrogen oxides and possibly halogens. Subsequently, the particles provide surface for heterogeneous reactions with atmospheric trace gases. Thus, aerosol smog-chamber studies with appropriate precursors are needed to generate SOA with HULIS qualities in situ inside the smog chamber and study their possible interactions. Catechol and guaiacol were chosen as aromatic precursors for synthetic HULIS production. The SOA was produced in a 700 L aerosol smog chamber, equipped with a solar simulator. SOA formation from each precursor was investigated at simulated environmental conditions (humidity, light, and presence of oxidizers) and characterized with respect to HULIS properties by particle classifiers, Fourier Transform IR spectroscopy (by long-path absorption and attenuated total reflection), UV/VIS spectroscopy, high-resolution mass-spectroscopy and temperature-programmed-desorption mass-spectrometry. High-resolution imaging was obtained using Field Emission Gun Scanning Electron Microscopy (FEGSEM). After HULIS formation the aerosol particles were exposed to atmospheric halogen species to study their processing with those trace gases, released by sea salt-activation. Those investigations show that aromatic precursors like catechol and guaiacol are suitable to form synthetic HULIS for laboratory-scale measurements with physical and chemical properties described in literature. However, sunlight and relative humidity play a major role in particle production and composition of functional groups, which are the anchor points for heterogeneous atmospheric

  14. Surface modification of anatase nanoparticles with fused ring catecholate type ligands: a combined DFT and experimental study of optical properties

    NASA Astrophysics Data System (ADS)

    Savić, Tatjana D.; Janković, Ivana A.; Šaponjić, Zoran V.; Čomor, Mirjana I.; Veljković, Dušan Ž.; Zarić, Snežana D.; Nedeljković, Jovan M.

    2012-02-01

    Surface modification of nanocrystalline TiO2 particles (45 Å) with catecholate-type ligands consisting of an extended aromatic ring system, i.e., 2,3-dihydroxynaphthalene and anthrarobin, was found to alter the optical properties of the nanoparticles in a similar way to modification with catechol. The formation of inner-sphere charge-transfer (CT) complexes results in a red shift of the semiconductor absorption compared to unmodified nanocrystallites and the reduction of the band gap upon the increase of the electron delocalization on the inclusion of additional rings. The binding structures were investigated by FTIR spectroscopy. The investigated ligands have the optimal geometry for binding to surface Ti atoms, resulting in ring coordination complexes of catecholate type (binuclear bidentate binding-bridging) thus restoring the six-coordinated octahedral geometry of surface Ti atoms. From the Benesi-Hildebrand plot, stability constants in methanol/water = 90/10 solutions at pH 2 of the order 103 M-1 have been determined. Quantum chemical calculations on model systems using density functional theory (DFT) were performed to obtain vibrational frequencies of charge transfer complexes, and the calculated values were compared with the experimental data.Surface modification of nanocrystalline TiO2 particles (45 Å) with catecholate-type ligands consisting of an extended aromatic ring system, i.e., 2,3-dihydroxynaphthalene and anthrarobin, was found to alter the optical properties of the nanoparticles in a similar way to modification with catechol. The formation of inner-sphere charge-transfer (CT) complexes results in a red shift of the semiconductor absorption compared to unmodified nanocrystallites and the reduction of the band gap upon the increase of the electron delocalization on the inclusion of additional rings. The binding structures were investigated by FTIR spectroscopy. The investigated ligands have the optimal geometry for binding to surface Ti atoms

  15. Enhancement of fill factor in air-processed inverted organic solar cells using self-assembled monolayer of fullerene catechol

    NASA Astrophysics Data System (ADS)

    Jeon, Il; Ogumi, Keisuke; Nakagawa, Takafumi; Matsuo, Yutaka

    2016-08-01

    [60]Fullerene catechol self-assembled monolayers were prepared and applied to inverted organic solar cells by an immersion method, and their energy conversion properties were measured. By introducing fullerenes at the surface, we improved the hole-blocking capability of electron-transporting metal oxide, as shown by the fill factor enhancement. The fullerene catechol-treated TiO x -containing device gave a power conversion efficiency (PCE) of 2.81% with a fill factor of 0.56 while the non treated device gave a PCE of 2.46% with a fill factor of 0.49. The solar cell efficiency improved by 13% compared with the non treated reference device.

  16. Synthesis, structure, spectra and reactivity of iron(III) complexes of facially coordinating and sterically hindering 3N ligands as models for catechol dioxygenases.

    PubMed

    Sundaravel, Karuppasamy; Dhanalakshmi, Thirumanasekaran; Suresh, Eringathodi; Palaniandavar, Mallayan

    2008-12-28

    DMF solution and the extradiol to intradiol product selectivity (E/I, 7.2 : 1-18.5 : 1) observed decreases upon increasing the steric bulk of N-alkyl substituent on the terminal nitrogen atom and upon incorporating an N-alkyl substituent on the central nitrogen atom. The plot of log(k(O(2))) vs. energy of the low energy catecholate-iron(III) LMCT band is linear, which is consistent with the proposal that the LMCT band energy corresponds to the energy needed for a spin-inversion process at the iron center upon dioxygen attack. Also, the rate of oxygenation is dictated by the solvent as well as the Lewis acidity of the iron(III) center, as shown by the linear plot of log(k(O(2))) vs.E(1/2) of the Fe(III)/Fe(II) redox potentials of the [Fe(L)(Sol)(3)](3+) complexes. PMID:19050788

  17. Association of codon 108/158 catechol-O-methyltransferase gene polymorphism with the psychiatric manifestations of velo-cardio-facial syndrome

    SciTech Connect

    Lachman, H.M.; Papolos, D.F.; Veit, S.

    1996-09-20

    Velo-cardio-facial-syndrome (VCFS) is a common congenital disorder associated with typical facial appearance, cleft palate, cardiac defects, and learning disabilities. The majority of patients have an interstitial deletion on chromosome 22q11. In addition to physical abnormalities, a variety of psychiatric illnesses have been reported in patients with VCFS, including schizophrenia, bipolar disorder, and attention deficit hyperactivity disorder. The psychiatric manifestations of VCFS could be due to haploinsufficiency of a gene(s) within 22q11. One candidate that has been mapped to this region is catechol-O-methyltransferase (COMT). We recently identified a polymorphism in the COMT gene that leads to a valine{r_arrow}methionine substitution at amino acid 158 of the membrane-bound form of the enzyme. Homozygosity for COMT158{sup met} leads to a 3- to 4-fold reduction in enzymatic activity, compared with homozygotes for COMT158{sup met}. We now report that in a population of patients with VCFS, there is an apparent association between the low-activity allele, COMT158{sup met}, and the development of bipolar spectrum disorder, and in particular, a rapid-cycling form. 33 refs., 3 tabs.

  18. Determination of catechol-O-methyltransferase activity in brain tissue by high-performance liquid chromatography with on-line radiochemical detection

    SciTech Connect

    Nissinen, E.

    1985-01-01

    A sensitive assay for catechol-O-methyltransferase (COMT) activity by high-performance liquid chromatography with on-line radiochemical detection was described. The method was based on the measurement of /sup 3/H- labeled 3-O- and 4-O-methylated products of the substrate, 3,4- dihydroxybenzoic acid, using S-adenosyl-L-(methyl-/sup 3/H)methionine as the methyl donor, or the measurement of /sup 14/C-labeled 3-O- and 4-O-methylated products of the substrate, (7-/sup 14/C)dopamine. The reaction products were determined from the incubation mixture after removal of protein by injecting an aliquot into the liquid chromatograph. The detection limit with counting efficiency of 40% was 0.45 pmol /sup 3/H-labeled product, and 0. 04 pmol /sup 14/C-labeled product with 61% counting efficiency. The method is suitable for assaying membrane-bound and soluble COMT activities in the brain tissue and for calculation of meta/para product ratios.

  19. Aurone synthase is a catechol oxidase with hydroxylase activity and provides insights into the mechanism of plant polyphenol oxidases.

    PubMed

    Molitor, Christian; Mauracher, Stephan Gerhard; Rompel, Annette

    2016-03-29

    Tyrosinases and catechol oxidases belong to the family of polyphenol oxidases (PPOs). Tyrosinases catalyze theo-hydroxylation and oxidation of phenolic compounds, whereas catechol oxidases were so far defined to lack the hydroxylation activity and catalyze solely the oxidation of o-diphenolic compounds. Aurone synthase from Coreopsis grandiflora (AUS1) is a specialized plant PPO involved in the anabolic pathway of aurones. We present, to our knowledge, the first crystal structures of a latent plant PPO, its mature active and inactive form, caused by a sulfation of a copper binding histidine. Analysis of the latent proenzyme's interface between the shielding C-terminal domain and the main core provides insights into its activation mechanisms. As AUS1 did not accept common tyrosinase substrates (tyrosine and tyramine), the enzyme is classified as a catechol oxidase. However, AUS1 showed hydroxylase activity toward its natural substrate (isoliquiritigenin), revealing that the hydroxylase activity is not correlated with the acceptance of common tyrosinase substrates. Therefore, we propose that the hydroxylase reaction is a general functionality of PPOs. Molecular dynamics simulations of docked substrate-enzyme complexes were performed, and a key residue was identified that influences the plant PPO's acceptance or rejection of tyramine. Based on the evidenced hydroxylase activity and the interactions of specific residues with the substrates during the molecular dynamics simulations, a novel catalytic reaction mechanism for plant PPOs is proposed. The presented results strongly suggest that the physiological role of plant catechol oxidases were previously underestimated, as they might hydroxylate their--so far unknown--natural substrates in vivo.

  20. Aurone synthase is a catechol oxidase with hydroxylase activity and provides insights into the mechanism of plant polyphenol oxidases.

    PubMed

    Molitor, Christian; Mauracher, Stephan Gerhard; Rompel, Annette

    2016-03-29

    Tyrosinases and catechol oxidases belong to the family of polyphenol oxidases (PPOs). Tyrosinases catalyze theo-hydroxylation and oxidation of phenolic compounds, whereas catechol oxidases were so far defined to lack the hydroxylation activity and catalyze solely the oxidation of o-diphenolic compounds. Aurone synthase from Coreopsis grandiflora (AUS1) is a specialized plant PPO involved in the anabolic pathway of aurones. We present, to our knowledge, the first crystal structures of a latent plant PPO, its mature active and inactive form, caused by a sulfation of a copper binding histidine. Analysis of the latent proenzyme's interface between the shielding C-terminal domain and the main core provides insights into its activation mechanisms. As AUS1 did not accept common tyrosinase substrates (tyrosine and tyramine), the enzyme is classified as a catechol oxidase. However, AUS1 showed hydroxylase activity toward its natural substrate (isoliquiritigenin), revealing that the hydroxylase activity is not correlated with the acceptance of common tyrosinase substrates. Therefore, we propose that the hydroxylase reaction is a general functionality of PPOs. Molecular dynamics simulations of docked substrate-enzyme complexes were performed, and a key residue was identified that influences the plant PPO's acceptance or rejection of tyramine. Based on the evidenced hydroxylase activity and the interactions of specific residues with the substrates during the molecular dynamics simulations, a novel catalytic reaction mechanism for plant PPOs is proposed. The presented results strongly suggest that the physiological role of plant catechol oxidases were previously underestimated, as they might hydroxylate their--so far unknown--natural substrates in vivo. PMID:26976571

  1. In Situ Synthesis of Antimicrobial Silver Nanoparticles within Antifouling Zwitterionic Hydrogels by Catecholic Redox Chemistry for Wound Healing Application.

    PubMed

    GhavamiNejad, Amin; Park, Chan Hee; Kim, Cheol Sang

    2016-03-14

    A multifunctional hydrogel that combines the dual functionality of both antifouling and antimicrobial capacities holds great potential for many bioapplications. Many approaches and different materials have been employed to synthesize such a material. However, a systematic study, including in vitro and in vivo evaluation, on such a material as wound dressings is highly scarce at present. Herein, we report on a new strategy that uses catecholic chemistry to synthesize antimicrobial silver nanoparticles impregnated into antifouling zwitterionic hydrogels. For this purpose, hydrophobic dopamine methacrylamide monomer (DMA) was mixed in an aqueous solution of sodium tetraborate decahydrate and DMA monomer became soluble after increasing pH to 9 due to the complexation between catechol groups and boron. Then, cross-linking polymerization of zwitterionic monomer was carried out with the solution of the protected dopamine monomer to produce a new hydrogel. When this new hydrogel comes in contact with a silver nitrate solution, silver nanoparticles (AgNPs) are formed in its structure as a result of the redox property of the catechol groups and in the absence of any other external reducing agent. The results obtained from TEM and XRD measurements indicate that AgNPs with diameters of around 20 nm had formed within the networks. FESEM images confirmed that the silver nanoparticles were homogeneously incorporated throughout the hydrogel network, and FTIR spectroscopy demonstrated that the catechol moiety in the polymeric backbone of the hydrogel is responsible for the reduction of silver ions into the AgNPs. Finally, the in vitro and in vivo experiments suggest that these mussel-inspired, antifouling, antibacterial hydrogels have great potential for use in wound healing applications.

  2. Aurone synthase is a catechol oxidase with hydroxylase activity and provides insights into the mechanism of plant polyphenol oxidases

    PubMed Central

    Molitor, Christian; Mauracher, Stephan Gerhard

    2016-01-01

    Tyrosinases and catechol oxidases belong to the family of polyphenol oxidases (PPOs). Tyrosinases catalyze the o-hydroxylation and oxidation of phenolic compounds, whereas catechol oxidases were so far defined to lack the hydroxylation activity and catalyze solely the oxidation of o-diphenolic compounds. Aurone synthase from Coreopsis grandiflora (AUS1) is a specialized plant PPO involved in the anabolic pathway of aurones. We present, to our knowledge, the first crystal structures of a latent plant PPO, its mature active and inactive form, caused by a sulfation of a copper binding histidine. Analysis of the latent proenzyme’s interface between the shielding C-terminal domain and the main core provides insights into its activation mechanisms. As AUS1 did not accept common tyrosinase substrates (tyrosine and tyramine), the enzyme is classified as a catechol oxidase. However, AUS1 showed hydroxylase activity toward its natural substrate (isoliquiritigenin), revealing that the hydroxylase activity is not correlated with the acceptance of common tyrosinase substrates. Therefore, we propose that the hydroxylase reaction is a general functionality of PPOs. Molecular dynamics simulations of docked substrate–enzyme complexes were performed, and a key residue was identified that influences the plant PPO’s acceptance or rejection of tyramine. Based on the evidenced hydroxylase activity and the interactions of specific residues with the substrates during the molecular dynamics simulations, a novel catalytic reaction mechanism for plant PPOs is proposed. The presented results strongly suggest that the physiological role of plant catechol oxidases were previously underestimated, as they might hydroxylate their—so far unknown—natural substrates in vivo. PMID:26976571

  3. Optical Absorption Spectra and Excitons of Dye-Substrate Interfaces: Catechol on TiO2(110).

    PubMed

    Mowbray, Duncan John; Migani, Annapaola

    2016-06-14

    Optimizing the photovoltaic efficiency of dye-sensitized solar cells (DSSC) based on staggered gap heterojunctions requires a detailed understanding of sub-band gap transitions in the visible from the dye directly to the substrate's conduction band (CB) (type-II DSSCs). Here, we calculate the optical absorption spectra and spatial distribution of bright excitons in the visible region for a prototypical DSSC, catechol on rutile TiO2(110), as a function of coverage and deprotonation of the OH anchoring groups. This is accomplished by solving the Bethe-Salpeter equation (BSE) based on hybrid range-separated exchange and correlation functional (HSE06) density functional theory (DFT) calculations. Such a treatment is necessary to accurately describe the interfacial level alignment and the weakly bound charge transfer transitions that are the dominant absorption mechanism in type-II DSSCs. Our HSE06 BSE spectra agree semiquantitatively with spectra measured for catechol on anatase TiO2 nanoparticles. Our results suggest deprotonation of catechol's OH anchoring groups, while being nearly isoenergetic at high coverages, shifts the onset of the absorption spectra to lower energies, with a concomitant increase in photovoltaic efficiency. Further, the most relevant bright excitons in the visible region are rather intense charge transfer transitions with the electron and hole spatially separated in both the [110] and [001] directions. Such detailed information on the absorption spectra and excitons is only accessible via periodic models of the combined dye-substrate interface. PMID:27183273

  4. Gene Cluster Involved in the Biosynthesis of Griseobactin, a Catechol-Peptide Siderophore of Streptomyces sp. ATCC 700974▿

    PubMed Central

    Patzer, Silke I.; Braun, Volkmar

    2010-01-01

    The main siderophores produced by streptomycetes are desferrioxamines. Here we show that Streptomyces sp. ATCC 700974 and several Streptomyces griseus strains, in addition, synthesize a hitherto unknown siderophore with a catechol-peptide structure, named griseobactin. The production is repressed by iron. We sequenced a 26-kb DNA region comprising a siderophore biosynthetic gene cluster encoding proteins similar to DhbABCEFG, which are involved in the biosynthesis of 2,3-dihydroxybenzoate (DHBA) and in the incorporation of DHBA into siderophores via a nonribosomal peptide synthetase. Adjacent to the biosynthesis genes are genes that encode proteins for the secretion, uptake, and degradation of siderophores. To correlate the gene cluster with griseobactin synthesis, the dhb genes in ATCC 700974 were disrupted. The resulting mutants no longer synthesized DHBA and griseobactin; production of both was restored by complementation with the dhb genes. Heterologous expression of the dhb genes or of the entire griseobactin biosynthesis gene cluster in the catechol-negative strain Streptomyces lividans TK23 resulted in the synthesis and secretion of DHBA or griseobactin, respectively, suggesting that these genes are sufficient for DHBA and griseobactin biosynthesis. Griseobactin was purified and characterized; its structure is consistent with a cyclic and, to a lesser extent, linear form of the trimeric ester of 2,3-dihydroxybenzoyl-arginyl-threonine complexed with aluminum under iron-limiting conditions. This is the first report identifying the gene cluster for the biosynthesis of DHBA and a catechol siderophore in Streptomyces. PMID:19915026

  5. Genetic influences on insight problem solving: the role of catechol-O-methyltransferase (COMT) gene polymorphisms

    PubMed Central

    Jiang, Weili; Shang, Siyuan; Su, Yanjie

    2015-01-01

    People may experience an “aha” moment, when suddenly realizing a solution of a puzzling problem. This experience is called insight problem solving. Several findings suggest that catecholamine-related genes may contribute to insight problem solving, among which the catechol-O-methyltransferase (COMT) gene is the most promising candidate. The current study examined 753 healthy individuals to determine the associations between 7 candidate single nucleotide polymorphisms on the COMT gene and insight problem-solving performance, while considering gender differences. The results showed that individuals carrying A allele of rs4680 or T allele of rs4633 scored significantly higher on insight problem-solving tasks, and the COMT gene rs5993883 combined with gender interacted with correct solutions of insight problems, specifically showing that this gene only influenced insight problem-solving performance in males. This study presents the first investigation of the genetic impact on insight problem solving and provides evidence that highlights the role that the COMT gene plays in insight problem solving. PMID:26528222

  6. Effects of 4-tertiary butyl catechol on melanocytes of hairless mice.

    PubMed

    Hoshino, S; Nishimura, M; Fukuyama, K; Gellin, G A; Epstein, J H

    1981-04-01

    Depigmentary effects of 4-tertiary butyl catechol (TBC) on UV-stimulated melanocytes on the flanks and naturally active melanocytes of ears were compared in Uscd strain hairless mice. UVB irradiation, twice a week for 1 or 2 mo, induced brown-black pigmentation on the flanks. A 1 M TBC application twice a week for 1 mo not only prevented the UV-stimulated pigmentation, but also promoted fading of the post-UV tanning. Dopa-stained split epidermal sheets showed a decrease in the number of melanocytes to less than one-half during the first month of TBC treatment. Melanocytes were often enlarged or lost their dendrites, and both premelanosomes and melanosomes showed ultrastructural changes. However, TBC application on the ears for 1 mo showed neither color change nor a decrease in the number of melanocytes. There were ultrastructural changes in melanocytes but the degree of abnormality was much less than those seen in UV-stimulated melanocytes. Continuation of TBC application for 2 mo with the UV irradiation on the flanks or the nonirradiated ears caused an increase in the number of melanocytes. These results suggest that the initial effect of TBC may be primarily cytotoxicity to melanocytes, and may correlate with their cellular functions. The stimulatory effects of TBC on melanocytes seen during the longer period of time requires further investigation.

  7. Gauging and Tuning Cross-Linking Kinetics of Catechol-PEG Adhesives via Catecholamine Functionalization.

    PubMed

    Paez, Julieta I; Ustahüseyin, Oya; Serrano, Cristina; Ton, Xuan-Anh; Shafiq, Zahid; Auernhammer, Günter K; d'Ischia, Marco; del Campo, Aránzazu

    2015-12-14

    The curing time of an adhesive material is determined by the polymerization and cross-linking kinetics of the adhesive formulation and needs to be optimized for the particular application. Here, we explore the possibility of tuning the polymerization kinetics and final mechanical properties of tissue-adhesive PEG gels formed by polymerization of end-functionalized star-PEGs with catecholamines with varying substituents. We show strong differences in cross-linking time and cohesiveness of the final gels among the catecholamine-PEG variants. Installation of an electron-withdrawing but π-electron donating chloro substituent on the catechol ring resulted in faster and more efficient cross-linking, while opposite effects were observed with the strongly electron-withdrawing nitro group. Chain substitution slowed down the kinetics and hindered cross-linking due either to chain breakdown (β-OH group, in norepinephrine) or intramolecular cyclization (α-carboxyl group, in DOPA). Interesting perspectives derive from use of mixtures of catecholamine-PEG precursors offering further opportunities for fine-tuning of the curing parameters. These are interesting properties for the application of catecholamine-PEG gels as tissue glues or biomaterials for cell encapsulation. PMID:26583428

  8. Genetic influences on insight problem solving: the role of catechol-O-methyltransferase (COMT) gene polymorphisms.

    PubMed

    Jiang, Weili; Shang, Siyuan; Su, Yanjie

    2015-01-01

    People may experience an "aha" moment, when suddenly realizing a solution of a puzzling problem. This experience is called insight problem solving. Several findings suggest that catecholamine-related genes may contribute to insight problem solving, among which the catechol-O-methyltransferase (COMT) gene is the most promising candidate. The current study examined 753 healthy individuals to determine the associations between 7 candidate single nucleotide polymorphisms on the COMT gene and insight problem-solving performance, while considering gender differences. The results showed that individuals carrying A allele of rs4680 or T allele of rs4633 scored significantly higher on insight problem-solving tasks, and the COMT gene rs5993883 combined with gender interacted with correct solutions of insight problems, specifically showing that this gene only influenced insight problem-solving performance in males. This study presents the first investigation of the genetic impact on insight problem solving and provides evidence that highlights the role that the COMT gene plays in insight problem solving.

  9. Analysis of oxidative stress status, catalase and catechol-O-methyltransferase polymorphisms in Egyptian vitiligo patients.

    PubMed

    Mehaney, Dina A; Darwish, Hebatallah A; Hegazy, Rehab A; Nooh, Mohammed M; Tawdy, Amira M; Gawdat, Heba I; El-Sawalhi, Maha M

    2014-01-01

    Vitiligo is the most common depigmentation disorder of the skin. Oxidative stress is implicated as one of the probable events involved in vitiligo pathogenesis possibly contributing to melanocyte destruction. Evidence indicates that certain genes including those involved in oxidative stress and melanin synthesis are crucial for development of vitiligo. This study evaluates the oxidative stress status, the role of catalase (CAT) and catechol-O-Methyltransferase (COMT) gene polymorphisms in the etiology of generalized vitiligo in Egyptians. Total antioxidant capacity (TAC) and malondialdehyde (MDA) levels as well as CAT exon 9 T/C and COMT 158 G/A polymorphisms were determined in 89 patients and 90 age and sex-matched controls. Our results showed significantly lower TAC along with higher MDA levels in vitiligo patients compared with controls. Meanwhile, genotype and allele distributions of CAT and COMT polymorphisms in cases were not significantly different from those of controls. Moreover, we found no association between both polymorphisms and vitiligo susceptibility. In conclusion, the enhanced oxidative stress with the lack of association between CAT and COMT polymorphisms and susceptibility to vitiligo in our patients suggest that mutations in other genes related to the oxidative pathway might contribute to the etiology of generalized vitiligo in Egyptian population.

  10. Crystal structure of a plant catechol oxidase containing a dicopper center.

    PubMed

    Klabunde, T; Eicken, C; Sacchettini, J C; Krebs, B

    1998-12-01

    Catechol oxidases are ubiquitous plant enzymes containing a dinuclear copper center. In the wound-response mechanism of the plant they catalyze the oxidation of a broad range of ortho-diphenols to the corresponding o-quinones coupled with the reduction of oxygen to water. The crystal structures of the enzyme from sweet potato in the resting dicupric Cu(II)-Cu(II) state, the reduced dicuprous Cu(I)-Cu(I) form, and in complex with the inhibitor phenylthiourea were analyzed. The catalytic copper center is accommodated in a central four-helix-bundle located in a hydrophobic pocket close to the surface. Both metal binding sites are composed of three histidine ligands. His 109, ligated to the CuA site, is covalently linked to Cys 92 by an unusual thioether bond. Based on biochemical, spectroscopic and the presented structural data, a catalytical mechanism is proposed in which one of the oxygen atoms of the diphenolic substrate binds to CuB of the oxygenated enzyme. PMID:9846879

  11. Catechol-O-methyltransferase val(158)met Polymorphism Interacts with Sex to Affect Face Recognition Ability.

    PubMed

    Lamb, Yvette N; McKay, Nicole S; Singh, Shrimal S; Waldie, Karen E; Kirk, Ian J

    2016-01-01

    The catechol-O-methyltransferase (COMT) val158met polymorphism affects the breakdown of synaptic dopamine. Consequently, this polymorphism has been associated with a variety of neurophysiological and behavioral outcomes. Some of the effects have been found to be sex-specific and it appears estrogen may act to down-regulate the activity of the COMT enzyme. The dopaminergic system has been implicated in face recognition, a form of cognition for which a female advantage has typically been reported. This study aimed to investigate potential joint effects of sex and COMT genotype on face recognition. A sample of 142 university students was genotyped and assessed using the Faces I subtest of the Wechsler Memory Scale - Third Edition (WMS-III). A significant two-way interaction between sex and COMT genotype on face recognition performance was found. Of the male participants, COMT val homozygotes and heterozygotes had significantly lower scores than met homozygotes. Scores did not differ between genotypes for female participants. While male val homozygotes had significantly lower scores than female val homozygotes, no sex differences were observed in the heterozygotes and met homozygotes. This study contributes to the accumulating literature documenting sex-specific effects of the COMT polymorphism by demonstrating a COMT-sex interaction for face recognition, and is consistent with a role for dopamine in face recognition. PMID:27445927

  12. Is catechol-o-methyltransferase gene polymorphism a risk factor in the development of premenstrual syndrome?

    PubMed Central

    Deveci, Esma Ozturk; Selek, Salih; Camuzcuoglu, Aysun; Hilali, Nese Gul; Camuzcuoglu, Hakan; Erdal, Mehmet Emin; Vural, Mehmet

    2014-01-01

    Objective The objective of this study was to investigate whether there was a correlation between catechol-o-methyltransferase (COMT) gene polymorphism, which is believed to play a role in the etiology of psychotic disorders, and premenstrual syndrome (PMS). Methods Fifty-three women with regular menstrual cycles, aged between 18 and 46 years and diagnosed with PMS according to the American Congress of Obstetrics and Gynecology criteria were included in this study as the study group, and 53 healthy women having no health problems were selected as the controls. Venous blood was collected from all patients included in the study and kept at -18℃ prior to analysis. Results There was no significant difference between the groups in terms of demographic features such as age, body mass index, number of pregnancies, parity, and number of children. No statistically significant difference was observed in terms of COMT gene polymorphism (p=0.61) between women in the PMS and the control groups. However, a significant difference was found between arthralgia, which is an indicator of PMS, and low-enzyme activity COMT gene (Met/Met) polymorphism (p=0.04). Conclusion These results suggested that there was no significant relationship between PMS and COMT gene polymorphism. Since we could not find a direct correlation between the COMT gene polymorphism and PMS, further studies including alternative neurotransmitter pathways are needed to find an effective treatment for this disease. PMID:25045629

  13. A catechol-O-methyltransferase that is essential for auditory function in mice and humans

    PubMed Central

    Du, Xin; Schwander, Martin; Moresco, Eva Marie Y.; Viviani, Pia; Haller, Claudia; Hildebrand, Michael S.; Pak, Kwang; Tarantino, Lisa; Roberts, Amanda; Richardson, Heather; Koob, George; Najmabadi, Hossein; Ryan, Allen F.; Smith, Richard J. H.; Müller, Ulrich; Beutler, Bruce

    2008-01-01

    We have identified a previously unannotated catechol-O-methyltranferase (COMT), here designated COMT2, through positional cloning of a chemically induced mutation responsible for a neurobehavioral phenotype. Mice homozygous for a missense mutation in Comt2 show vestibular impairment, profound sensorineuronal deafness, and progressive degeneration of the organ of Corti. Consistent with this phenotype, COMT2 is highly expressed in sensory hair cells of the inner ear. COMT2 enzymatic activity is significantly reduced by the missense mutation, suggesting that a defect in catecholamine catabolism underlies the auditory and vestibular phenotypes. Based on the studies in mice, we have screened DNA from human families and identified a nonsense mutation in the human ortholog of the murine Comt2 gene that causes nonsyndromic deafness. Defects in catecholamine modification by COMT have been previously implicated in the development of schizophrenia. Our studies identify a previously undescribed COMT gene and indicate an unexpected role for catecholamines in the function of auditory and vestibular sense organs. PMID:18794526

  14. Formation of dibenzofuran, dibenzo-p-dioxin and their hydroxylated derivatives from catechol.

    PubMed

    Altarawneh, Mohammednoor; Dlugogorski, Bogdan Z

    2015-01-21

    We present, in this study, mechanistic and kinetic accounts of the formation of dibenzofuran (DF), dibenzo-p-dioxin (DD) and their hydroxylated derivatives (OHs-DF/OHs-DD) from the catechol (CT) molecule, as a model compound for phenolic constituents in biomass. Self-condensation of two CT molecules produces predominantly a DD molecule via open- and closed-shell corridors. Coupling modes involving the o-semiquinone radical and the CT molecule (o-SQ/CT) generate two direct structural blocks for the formation of OHs-DF/OHs-DD structures, ether-type intermediates and di-keto moieties. The calculated reaction rate constants indicate that the fate of ether-type intermediates is to make hydroxylated diphenyl ethers rather than to undergo cyclisation reactions leading to the formation of preDF structures. Unimolecular loss of a H or OH moiety from a pivotal carbon in these hydroxylated diphenyl ethers then produces hydroxylated and non-hydroxylated DD molecules. Formation of OHs-DF initiated by o(C)-o(C) cross-linkages involving o-SQ/o-SQ and o-SQ/CT reactions incurs very similar reaction and activation enthalpies encountered in the formation of chlorinated DFs from chlorophenols.

  15. Mussel inspired modification of polypropylene separators by catechol/polyamine for Li-ion batteries.

    PubMed

    Wang, Hao; Wu, Junjie; Cai, Chao; Guo, Jing; Fan, Haosen; Zhu, Caizhen; Dong, Haixia; Zhao, Ning; Xu, Jian

    2014-04-23

    Inspired by the remarkable adhesion of mussel, dopamine, a mimicking adhesive molecule, has been widely used for surface modification of various materials ranging from organic to inorganic. However, dopamine and its derivatives are expensive which impede their application in large scale. Herein, we replaced dopamine with low-cost catechol and polyamine (only 8% of the cost of dopamine), which could be polymerized in an alkaline solution and deposited on the surfaces of various materials. By using this cheap and simple modification method, polypropylene (PP) separator could be transformed from hydrophobic to hydrophilic, while the pore structure and mechanical property of the separator remained intact. The uptake of electrolyte increased from 80% to 270% after the hydrophilic modification. Electrochemical studies demonstrated that battery with the modified PP separator had a better Coulombic efficiency (80.9% to 85.3%) during the first cycle at a current density of 0.1 C, while the discharging current density increased to 15 C and the discharge capacity increased by 1.4 times compared to the battery using the bare PP separator. Additionally, the modification allowed excellent stability during manifold cycles. This study provides new insights into utilizing low-cost chemicals to mimic the mussel adhesion and has potential practical application in many fields. PMID:24684271

  16. The role of catechol-O-methyltransferase in reward processing and addiction.

    PubMed

    Tunbridge, E M; Huber, A; Farrell, S M; Stumpenhorst, K; Harrison, P J; Walton, M E

    2012-05-01

    Catechol-O-methyltransferase (COMT) catabolises dopamine and is important for regulating dopamine levels in the prefrontal cortex. Consistent with its regulation of prefrontal cortex dopamine, COMT modulates working memory and executive function; however, its significance for other cognitive domains, and in other brain regions, remains relatively unexplored. One such example is reward processing, for which dopamine is a critical mediator, and in which the striatum and corticostriatal circuitry are implicated. Here, we discuss emerging data which links COMT to reward processing, review what is known of the underlying neural substrates, and consider whether COMT is a good therapeutic target for treating addiction. Although a limited number of studies have investigated COMT and reward processing, common findings are beginning to emerge. COMT appears to modulate cortical and striatal activation during both reward anticipation and delivery, and to impact on reward-related learning and its underlying neural circuitry. COMT has been studied as a candidate gene for numerous reward-related phenotypes and there is some preliminary evidence linking it with certain aspects of addiction. However, additional studies are required before these associations can be considered robust. It is premature to consider COMT a good therapeutic target for addiction, but this hypothesis should be revisited as further information emerges. In particular, it will be critical to reveal the precise neurobiological mechanisms underlying links between COMT and reward processing, and the extent to which these relate to the putative associations with addiction. PMID:22483300

  17. Catechol-O-methyltransferase (COMT) gene modulates private self-consciousness and self-flexibility.

    PubMed

    Wang, Bei; Ru, Wenzhao; Yang, Xing; Yang, Lu; Fang, Pengpeng; Zhu, Xu; Shen, Guomin; Gao, Xiaocai; Gong, Pingyuan

    2016-08-01

    Dopamine levels in the brain influence human consciousness. Inspired by the role of Catechol-O-methyltransferase (COMT) in inactivating dopamine in the brain, we investigated to what extent COMT could modulate individual's self-consciousness dispositions and self-consistency by genotyping the COMT Val158Met (rs4680) polymorphism and measuring self-consciousness and self-consistency and congruence in a college student population. The results indicated that COMT Val158Met polymorphism significantly modulated the private self-consciousness. The individuals with Val/Val genotype, corresponding to lower dopamine levels in the brain, were more likely to be aware of their feelings and beliefs. The results also indicated that this polymorphism modulated one's self-flexibility. The individuals with Val/Val genotype showed higher levels of stereotype in self-concept compared with those with Met/Met genotype. These findings suggest that COMT is a predictor of the individual differences in self-consciousness and self-flexibility. PMID:27522491

  18. Schistosome and liver fluke derived catechol-estrogens and helminth associated cancers

    PubMed Central

    Correia da Costa, José M.; Vale, Nuno; Gouveia, Maria J.; Botelho, Mónica C.; Sripa, Banchob; Santos, Lúcio L.; Santos, Júlio H.; Rinaldi, Gabriel; Brindley, Paul J.

    2014-01-01

    Infection with helminth parasites remains a persistent public health problem in developing countries. Three of these pathogens, the liver flukes Clonorchis sinensis, Opisthorchis viverrini and the blood fluke Schistosoma haematobium, are of particular concern due to their classification as Group 1 carcinogens: infection with these worms is carcinogenic. Using liquid chromatography-mass spectrometry (LC-MS/MS) approaches, we identified steroid hormone like (e.g., oxysterol-like, catechol estrogen quinone-like, etc.) metabolites and related DNA-adducts, apparently of parasite origin, in developmental stages including eggs of S. haematobium, in urine of people with urogenital schistosomiasis, and in the adult stage of O. viverrini. Since these kinds of sterol derivatives are metabolized to active quinones that can modify DNA, which in other contexts can lead to breast and other cancers, helminth parasite associated sterols might induce tumor-like phenotypes in the target cells susceptible to helminth parasite associated cancers, i.e., urothelial cells of the bladder in the case of urogenital schistosomiasis and the bile duct epithelia or cholangiocytes, in the case of O. viverrini and C. sinensis. Indeed we postulate that helminth induced cancers originate from parasite estrogen-host epithelial/urothelial cell chromosomal DNA adducts, and here we review recent findings that support this conjecture. PMID:25566326

  19. Catechol-O-Methyltransferase val158met Polymorphism Predicts Placebo Effect in Irritable Bowel Syndrome

    PubMed Central

    Hall, Kathryn T.; Lembo, Anthony J.; Kirsch, Irving; Ziogas, Dimitrios C.; Douaiher, Jeffrey; Jensen, Karin B.; Conboy, Lisa A.; Kelley, John M.; Kokkotou, Efi; Kaptchuk, Ted J.

    2012-01-01

    Identifying patients who are potential placebo responders has major implications for clinical practice and trial design. Catechol-O-methyltransferase (COMT), an important enzyme in dopamine catabolism plays a key role in processes associated with the placebo effect such as reward, pain, memory and learning. We hypothesized that the COMT functional val158met polymorphism, was a predictor of placebo effects and tested our hypothesis in a subset of 104 patients from a previously reported randomized controlled trial in irritable bowel syndrome (IBS). The three treatment arms from this study were: no-treatment (“waitlist”), placebo treatment alone (“limited”) and, placebo treatment “augmented” with a supportive patient-health care provider interaction. The primary outcome measure was change from baseline in IBS-Symptom Severity Scale (IBS-SSS) after three weeks of treatment. In a regression model, the number of methionine alleles in COMT val158met was linearly related to placebo response as measured by changes in IBS-SSS (p = .035). The strongest placebo response occurred in met/met homozygotes treated in the augmented placebo arm. A smaller met/met associated effect was observed with limited placebo treatment and there was no effect in the waitlist control. These data support our hypothesis that the COMT val158met polymorphism is a potential biomarker of placebo response. PMID:23110189

  20. Catechol O-methyltransferase Val158Met polymorphism is associated with cognitive performance in nondemented adults.

    PubMed

    de Frias, Cindy M; Annerbrink, Kristina; Westberg, Lars; Eriksson, Elias; Adolfsson, Rolf; Nilsson, Lars-Göran

    2005-07-01

    The catechol O-methyltransferase (COMT) gene is essential in the metabolic degradation of dopamine in the prefrontal cortex. In the present study, we examined the effect of a Val158Met polymorphism in the COMT gene on individual differences and changes in cognition (executive functions and visuospatial ability) in adulthood and old age. The participants were 292 nondemented men (initially aged 35-85 years) from a random sample of the population (i.e., the Betula study) tested at two occasions with a 5-year interval. Confirmatory factor analyses were used to test the underlying structure of three indicators of executive functions (verbal fluency, working memory, and Tower of Hanoi). Associations between COMT, age, executive functioning, and visuospatial (block design) tasks were examined using repeated-measures analyses of variance. Carriers of the Val allele (with higher enzyme activity) compared with carriers of the Met/Met genotype (with low enzyme activity) performed worse on executive functioning and visuospatial tasks. Individuals with the Val/Val genotype declined in executive functioning over the 5-year period, whereas carriers of the Met allele remained stable in performance. An Age x COMT interaction for visuospatial ability located the effect for middle-aged men only. This COMT polymorphism is a plausible candidate gene for executive functioning and fluid intelligence in nondemented middle-aged and older adults. PMID:16102234

  1. Characterization of non-nitrocatechol pan and isoform specific catechol-O-methyltransferase inhibitors and substrates.

    PubMed

    Robinson, Ronald G; Smith, Sean M; Wolkenberg, Scott E; Kandebo, Monika; Yao, Lihang; Gibson, Christopher R; Harrison, Scott T; Polsky-Fisher, Stacey; Barrow, James C; Manley, Peter J; Mulhearn, James J; Nanda, Kausik K; Schubert, Jeffrey W; Trotter, B Wesley; Zhao, Zhijian; Sanders, John M; Smith, Robert F; McLoughlin, Debra; Sharma, Sujata; Hall, Dawn L; Walker, Tiffany L; Kershner, Jennifer L; Bhandari, Neetesh; Hutson, Pete H; Sachs, Nancy A

    2012-02-15

    Reduced dopamine neurotransmission in the prefrontal cortex has been implicated as causal for the negative symptoms and cognitive deficit associated with schizophrenia; thus, a compound which selectively enhances dopamine neurotransmission in the prefrontal cortex may have therapeutic potential. Inhibition of catechol-O-methyltransferase (COMT, EC 2.1.1.6) offers a unique advantage, since this enzyme is the primary mechanism for the elimination of dopamine in cortical areas. Since membrane bound COMT (MB-COMT) is the predominant isoform in human brain, a high throughput screen (HTS) to identify novel MB-COMT specific inhibitors was completed. Subsequent optimization led to the identification of novel, non-nitrocatechol COMT inhibitors, some of which interact specifically with MB-COMT. Compounds were characterized for in vitro efficacy versus human and rat MB and soluble (S)-COMT. Select compounds were administered to male Wistar rats, and ex vivo COMT activity, compound levels in plasma and cerebrospinal fluid (CSF), and CSF dopamine metabolite levels were determined as measures of preclinical efficacy. Finally, novel non-nitrocatechol COMT inhibitors displayed less potent uncoupling of the mitochondrial membrane potential (MMP) compared to tolcapone as well as nonhepatotoxic entacapone, thus mitigating the risk of hepatotoxicity. PMID:22860182

  2. Antiproliferative and Antiestrogenic Activities of Bonediol an Alkyl Catechol from Bonellia macrocarpa.

    PubMed

    Moo-Puc, Rosa; Caamal-Fuentes, Edgar; Peraza-Sánchez, Sergio R; Slusarz, Anna; Jackson, Glenn; Drenkhahn, Sara K; Lubahn, Dennis B

    2015-01-01

    The purpose of this study was to investigate antiproliferative activity of bonediol, an alkyl catechol isolated from the Mayan medicinal plant Bonellia macrocarpa. Bonediol was assessed for growth inhibition of androgen-sensitive (LNCaP), androgen-insensitive (PC-3), and metastatic androgen-insensitive (PC-3M) human prostate tumor cells; toxicity on normal cell line (HEK 293) was also evaluated. Hedgehog pathway was evaluated and competitive 3H-estradiol ligand binding assay was performed. Additionally, antioxidant activity on Nrf2-ARE pathway was evaluated. Bonediol induced a growth inhibition on prostate cancer cell lines (IC50 from 8.5 to 20.6 µM). Interestingly, bonediol binds to both estrogen receptors (ERα (2.5 µM) and ERβ (2.1 µM)) and displaces the native ligand E2 (17β-estradiol). No significant activity was found in the Hedgehog pathway. Additionally, activity of bonediol on Nrf2-ARE pathway suggested that bonediol could induce oxidative stress and activation of detoxification enzymes at 1 µM (3.8-fold). We propose that the compound bonediol may serve as a potential chemopreventive treatment with therapeutic potential against prostate cancer. PMID:26557704

  3. Catechol--an oviposition stimulant for cigarette beetle in roasted coffee beans.

    PubMed

    Nagasawa, Atsuhiko; Kamada, Yuji; Kosaka, Yuji; Arakida, Naohiro; Hori, Masatoshi

    2014-05-01

    The cigarette beetle, Lasioderma serricorne, is a serious global pest that preys on stored food products. Larvae of the beetle cannot grow on roasted coffee beans or dried black or green tea leaves, although they oviposit on such products. We investigated oviposition by the beetles on MeOH extracts of the above products. The number of eggs laid increased with an increase in dose of each extract, indicating that chemical factors stimulate oviposition by the beetles. This was especially true for \\ coffee bean extracts, which elicited high numbers of eggs even at a low dose (0.1 g bean equivalent/ml) compared to other extracts. Coffee beans were extracted in hexane, chloroform, 1-butanol, MeOH, and 20% MeOH in water. The number of eggs laid was higher on filter papers treated with chloroform, 1-butanol, MeOH, and 20% MeOH in water extracts than on control (solvent alone) papers. The chloroform extract was fractionated by silica-gel column chromatography. Nine compounds were identified by gas chromatography/mass spectrometry from an active fraction. Of these compounds, only a significant ovipositional response to catechol was observed.

  4. Catechol-O-methyltransferase val158met Polymorphism Interacts with Sex to Affect Face Recognition Ability

    PubMed Central

    Lamb, Yvette N.; McKay, Nicole S.; Singh, Shrimal S.; Waldie, Karen E.; Kirk, Ian J.

    2016-01-01

    The catechol-O-methyltransferase (COMT) val158met polymorphism affects the breakdown of synaptic dopamine. Consequently, this polymorphism has been associated with a variety of neurophysiological and behavioral outcomes. Some of the effects have been found to be sex-specific and it appears estrogen may act to down-regulate the activity of the COMT enzyme. The dopaminergic system has been implicated in face recognition, a form of cognition for which a female advantage has typically been reported. This study aimed to investigate potential joint effects of sex and COMT genotype on face recognition. A sample of 142 university students was genotyped and assessed using the Faces I subtest of the Wechsler Memory Scale – Third Edition (WMS-III). A significant two-way interaction between sex and COMT genotype on face recognition performance was found. Of the male participants, COMT val homozygotes and heterozygotes had significantly lower scores than met homozygotes. Scores did not differ between genotypes for female participants. While male val homozygotes had significantly lower scores than female val homozygotes, no sex differences were observed in the heterozygotes and met homozygotes. This study contributes to the accumulating literature documenting sex-specific effects of the COMT polymorphism by demonstrating a COMT-sex interaction for face recognition, and is consistent with a role for dopamine in face recognition. PMID:27445927

  5. Catechol-O-Methyltransferase Gene Polymorphisms in Specific Obsessive-Compulsive Disorder Patients' Subgroups.

    PubMed

    Melo-Felippe, Fernanda Brito; de Salles Andrade, Juliana Braga; Giori, Isabele Gomes; Vieira-Fonseca, Tamiris; Fontenelle, Leonardo Franklin; Kohlrausch, Fabiana Barzotti

    2016-01-01

    Pharmacological data and animal models support the hypothesis that the dopaminergic (DA) system is implicated in obsessive-compulsive disorder (OCD). Therefore, this case-control study assessed whether genetics variations in catechol-O-methyltransferase gene (COMT) could influence susceptibility to OCD and OCD features in a Brazilian sample. A sample of 199 patients with OCD and 200 healthy individuals was genotyped for -287A > G (rs2075507) and Val158Met (rs4680) single nucleotide polymorphisms (SNPs) by TaqMan(®) or restriction mapping. We observed a statistically significant predominance of the Met low-activity allele in the male patient group as compared to the male healthy control group. The -287A > G polymorphism's genotypes and alleles were significantly overrepresented among male individuals with ordering and female subjects with washing symptoms. We also found female hoarders to exhibit a significant higher frequency of the low activity Met/Met genotype of Val158Met polymorphism compared to female patients who did not express this dimension. Our data suggest an influence of COMT polymorphisms on OCD and OCD patients' features, such as gender, and ordering, washing, and hoarding symptom dimensions. Further studies to confirm the clinical importance of COMT SNPs in OCD are warranted.

  6. Mussel inspired modification of polypropylene separators by catechol/polyamine for Li-ion batteries.

    PubMed

    Wang, Hao; Wu, Junjie; Cai, Chao; Guo, Jing; Fan, Haosen; Zhu, Caizhen; Dong, Haixia; Zhao, Ning; Xu, Jian

    2014-04-23

    Inspired by the remarkable adhesion of mussel, dopamine, a mimicking adhesive molecule, has been widely used for surface modification of various materials ranging from organic to inorganic. However, dopamine and its derivatives are expensive which impede their application in large scale. Herein, we replaced dopamine with low-cost catechol and polyamine (only 8% of the cost of dopamine), which could be polymerized in an alkaline solution and deposited on the surfaces of various materials. By using this cheap and simple modification method, polypropylene (PP) separator could be transformed from hydrophobic to hydrophilic, while the pore structure and mechanical property of the separator remained intact. The uptake of electrolyte increased from 80% to 270% after the hydrophilic modification. Electrochemical studies demonstrated that battery with the modified PP separator had a better Coulombic efficiency (80.9% to 85.3%) during the first cycle at a current density of 0.1 C, while the discharging current density increased to 15 C and the discharge capacity increased by 1.4 times compared to the battery using the bare PP separator. Additionally, the modification allowed excellent stability during manifold cycles. This study provides new insights into utilizing low-cost chemicals to mimic the mussel adhesion and has potential practical application in many fields.

  7. Kinetic study of oxalic acid inhibition on enzymatic browning.

    PubMed

    Son, S M; Moon, K D; Lee, C Y

    2000-06-01

    Oxalic acid has a strong antibrowning activity. The inhibitory pattern on catechol-PPO model system appeared to be competitive, with a K(i) value of 2.0 mM. When the PPO was incubated with oxalic acid, the activity was not recovered via dialysis, but the inactivated enzyme partially recovered its activity when cupric ion was added. Comparing the relative antibrowning effectiveness of oxalic acid with other common antibrowning agents, oxalic acid with I(50) value of 1.1 mM is as effective as kojic acid and more potent than cysteine and glutathione.

  8. Characterization of an adsorbed humin-like substance on an allophanic soil formed via catalytic polycondensation between catechol and glycine, and its adsorption capability to pentachlorophenol.

    PubMed

    Okabe, Ryo; Miura, Akitaka; Fukushima, Masami; Terashima, Motoki; Sasaki, Masahide; Fukuchi, Shigeki; Sato, Tsutomu

    2011-06-01

    An allophanic soil (AS) catalyzed the formation of dark-colored polymers via polycondensation reactions between catechol and glycine. The organic carbon content of the AS was increased from 0.16% to 1.3%, indicating that some of the dark-colored polymers had been adsorbed to the AS. The characteristics of the dark-colored polymers adsorbed on the AS were similar to those of a humin that is not extractable with an aqueous alkaline solution. Such a humin-like substance (HuLS) was separated from the AS by treatment with a mixture of HF and HCl. The HuLS and humic acid-like substance (HaLS), comprising the acid-insoluble fraction in the reaction mixture, were characterized by elemental analysis, size exclusion chromatography, pyrolysis-GC/MS and (13)C NMR. However, the structural features of HaLS and HuLS had many points in common. These results suggest that HuLS-AS can be regarded as an organo-clay complex formed by the strong adsorption of HaLS to the AS. The adsorption of pentachlorophenol (PCP) to AS and HuLS-AS was examined at pH 5.5. At this pH, the zeta potential of the HuLS-AS showed a negative value. It would, therefore, be expected that pentachlorophenolate anions would adsorb with difficulty to HuLS-AS because of electrostatic repulsion. Nevertheless, the adsorption coefficient for PCP to HuLS-AS, as estimated by the Freundlich isotherm, was seven times larger than that for AS. These results show that HuLS, when adsorbed on the AS surface, has the capability to enhance the adsorption of PCP.

  9. Polymer pendant ligand chemistry. 3. A biomimetic approach to selective metal ion removal and recovery from aqueous solution with polymer-supported sulfonated catechol and linear catechol amide ligands

    SciTech Connect

    Huang, Song-Ping; Li, Wei; Franz, K.J.; Albright, R.L.; Fish, R.H.

    1995-05-24

    The design of organic ligands to selectively remove and recover metal ions from aqueous solution is a new and important area of environmental inorganic chemistry. One approach to designing organic ligands for these purposes is to use biological systems as examples for selective metal ion complexation. Thus, the authors report results on the synthesis of several biomimetically important polymer-supported, sulfonated catechol (PS-CATS), sulfonated bis(catechol) linear amide (PS-2-6-LICAMS), and sulfonated 3.3-linear tris(catechol) amide (PS-3,3-LICAMS) ligands that are chemically bonded to modified 6% cross-linked macroporous polystyrene-divinylbenzene beads (PS-DVB) for selective removal and recovery of environmentally and economically important metal ions from aqueous solution, as a function of pH. The Fe{sup 3+} ion selectivity was dramatically shown for PS-CATS, PS-2-6-LICAMS and PS-3,3-LICAMS polymer beads in competition with a similar concentration of Cu{sup 2+}, Zn{sup 2+}, Mn{sup 2+}, Ni{sup 2+}, Mg{sup 2+}, Al{sup 3+}, and Cr{sup 3+} ions at pH 1-3, while metal ion selectivity could be changed at higher pH values in the absence of Fe{sup 3+} (for example, Hg{sup 2+} at pH 3). Rates of removal and recovery of the Fe{sup 3+} ion with the PS-CATS, PS-2-6LICAMS and PS-3,3-LICAMS polymer beads were also studied as well as relative equilibrium selectivity coefficient (K{sub m}) values for all metal competition studies.

  10. "Additive" cooperativity of hydrogen bonds in complexes of catechol with proton acceptors in the gas phase: FTIR spectroscopy and quantum chemical calculations.

    PubMed

    Varfolomeev, Mikhail A; Klimovitskii, Alexander E; Abaidullina, Dilyara I; Madzhidov, Timur I; Solomonov, Boris N

    2012-06-01

    Experimental study of hydrogen bond cooperativity in hetero-complexes in the gas phase was carried out by IR-spectroscopy method. Stretching vibration frequencies of O-H groups in phenol and catechol molecules as well as of their complexes with nitriles and ethers were determined in the gas phase using a specially designed cell. O-H groups experimental frequency shifts in the complexes of catechol induced by the formation of intermolecular hydrogen bonds are significantly higher than in the complexes of phenol due to the hydrogen bond cooperativity. It was shown that the cooperativity factors of hydrogen bonds in the complexes of catechol with nitriles and ethers in the gas phase are approximately the same. Quantum chemical calculations of the studied systems have been performed using density functional theory (DFT) methods. It was shown, that theoretically obtained cooperativity factors of hydrogen bonds in the complexes of catechol with proton acceptors are in good agreement with experimental values. Cooperative effects lead to a strengthening of intermolecular hydrogen bonds in the complexes of catechol on about 30%, despite the significant difference in the proton acceptor ability of the bases. The analysis within quantum theory of atoms in molecules was carried out for the explanation of this fact.

  11. Effect of a natural mineral-rich water on catechol-O-methyltransferase function.

    PubMed

    Bastos, Pedro; Araújo, João Ricardo; Azevedo, Isabel; Martins, Maria João; Ribeiro, Laura

    2014-01-01

    Catechol-O-methyltransferase (COMT) is a magnesium-dependent, catecholamine-metabolizing enzyme, whose impaired activity has been positively associated with cardiovascular diseases, particularly hypertension. Consumption of some natural mineral-rich waters has been shown to exert protective effects on cardiovascular risk factors, eg. by decreasing arterial blood pressure and blood lipids. However, the molecular mechanisms underlying these effects are still poorly understood. So, the aim of this work was to investigate the effect of natural mineral-rich water ingestion upon liver and adrenal glands COMT expression and activity in Wistar Han rats. Over a seven-week period, animals had access to one of the following three drinking solutions: 1) tap water (control group; TW), 2) tap water with added Na(+) (to make the same concentration as in the MW group (TWNaCl group), or 3) natural mineral-rich water [Pedras Salgadas(®), which is very rich in bicarbonate, and with higher sodium, calcium and magnesium content than control tap water (MW group)]. COMT expression and activity were determined by RT-PCR and HPLC-ED, respectively. A higher hepatic COMT activity was found in the MW group compared with the TW and TWNaCl groups. On the other hand, adrenal gland COMT mRNA expression decreased in the MW group compared to TW group. In conclusion, the ability of natural mineral-rich waters to increase hepatic COMT activity may eventually explain the positive cardiovascular effects associated with the consumption of some natural mineral-rich waters. PMID:25560240

  12. Antibacterial activity of BMS-180680, a new catechol-containing monobactam.

    PubMed Central

    Fung-Tomc, J; Bush, K; Minassian, B; Kolek, B; Flamm, R; Gradelski, E; Bonner, D

    1997-01-01

    The in vitro activities of a new catechol-containing monobactam, BMS-180680 (SQ 84,100), were compared to those of aztreonam, ceftazidime, imipenem, piperacillin-tazobactam, ciprofloxacin, amikacin, and trimethoprim-sulfamethoxazole. BMS-180680 was often the most active compound against many species of the family Enterobacteriaceae, with MICs at which 90% of the isolates were inhibited (MIC90s) of < or = 0.5 microg/ml for Escherichia coli, Klebsiella spp., Citrobacter diversus, Enterobacter aerogenes, Serratia marcescens, Proteus spp., and Providencia spp. BMS-180680 had moderate activities (MIC90s of 2 to 8 microg/ml) against Citrobacter freundii, Morganella morganii, Shigella spp., and non-E. aerogenes Enterobacter spp. BMS-180680 was the only antibiotic evaluated that was active against >90% of the Pseudomonas aeruginosa (MIC90, 0.25 microg/ml), Burkholderia cepacia, and Stenotrophomonas maltophilia (MIC90s, 1 microg/ml) strains tested. BMS-180680 was inactive against most strains of Pseudomonas fluorescens, Pseudomonas stutzeri, Pseudomonas diminuta, and Burkholderia pickettii. BMS-180680 was moderately active (MIC90s of 4 to 8 microg/ml) against Alcaligenes spp. and Acinetobacter lwoffii and less active (MIC90, 16 microg/ml) against Acinetobacter calcoaceticus-Acinetobacter baumanii complex. BMS-180680 lacked activity against gram-positive bacteria and anaerobic bacteria. Both tonB and cir fiu double mutants of E. coli had greatly decreased susceptibility to BMS-180680. Of the TEM, PSE, and chromosomal-encoded beta-lactamases tested, only the K1 enzyme hydrolyzed BMS-180680 to any measurable extent. Like aztreonam, BMS-180680 bound preferentially to penicillin-binding protein 3. The MICs of BMS-180680 were not influenced by the presence of hematin or 5% sheep blood in the test medium or with incubation in an atmosphere containing 5% CO2. BMS-180680 MICs obtained under strict anaerobic conditions were significantly higher than those obtained in ambient air

  13. Mechanism for catechol ring cleavage by non-heme iron intradiol dioxygenases: a hybrid DFT study.

    PubMed

    Borowski, Tomasz; Siegbahn, Per E M

    2006-10-01

    The mechanism of the catalytic reaction of protocatechuate 3,4-dioxygenase (3,4-PCD), a representative intradiol dioxygenase, was studied with the hybrid density functional method B3LYP. First, a smaller model involving only the iron first-shell ligands (His460, His462, and Tyr408) and the substrates (catechol and dioxygen) was used to probe various a priori plausible reaction mechanisms. Then, an extended model involving also the most important second-shell groups (Arg457, Gln477, and Tyr479) was used for the refinement of the preselected mechanisms. The computational results suggest that the chemical reactions constituting the catalytic cycle of intradiol dioxygenases involve: (1) binding of the substrate as a dianion, in agreement with experimental suggestions, (2) binding of dioxygen to the metal aided by an electron transfer from the substrate to O(2), (3) formation of a bridging peroxo intermediate and its conformational change, which opens the coordination site trans to His462, (4) binding of a neutral XOH ligand (H(2)O or Tyr447) at the open site, (5) proton transfer from XOH to the neighboring peroxo ligand yielding the hydroperoxo intermediate, (6) a Criegee rearrangement leading to the anhydride intermediate, and (7) hydrolysis of the anhydride to the final acyclic product. One of the most important results obtained is that the Criegee mechanism requires an in-plane orientation of the four atoms (two oxygen and two carbon atoms) mainly involved in the reaction. This orientation yields a good overlap between the two sigma orbitals involved, C-C sigma and O-O sigma, allowing an efficient electron flow between them. Another interesting result is that under some conditions, a homolytic O-O bond cleavage might compete with the Criegee rearrangement. The role of the second-shell residues and the substituent effects are also discussed.

  14. Mechanistic studies of catechol generation from secondary quinone amines relevant to indole formation and tyrosinase activation.

    PubMed

    Land, Edward J; Ramsden, Christopher A; Riley, Patrick A; Yoganathan, Gnanamoly

    2003-08-01

    The biological significance of the spontaneous cyclization and redox reactions of ortho-quinone amines is that these appear to be the mechanism of formation of the indolic components of melanin and are also involved in the autoactivation of tyrosinase. We have previously shown that activation of tyrosinase is prevented by the formation of a cyclic betaine from a tertiary amine analogue. Evidence is presented to show that cyclization of ortho-quinones by Michael addition also occurs in the oxidation of secondary catecholamines. Three varieties of cyclic product have been detected and their formation is influenced by the nature of the N-substituent. Five-membered betaine rings form directly and, although six- and seven-membered rings also form, a transient spiro isomer of the ortho-quinone was in some cases detected as an intermediate. The heterocyclic products formed as betaines undergo redox exchange with residual quinone to form the corresponding aminochromes. We have established the kinetic constants of these reactions, either directly by pulse radiolysis measurements or by inference using a computer model of the reaction pathway to fit the observed data. To investigate the potential biological applications of this chemistry the system was also examined by tyrosinase-catalysed oxidation of the catecholamine substrates in which there is re-oxidation of the catechol formed by the redox exchange reaction and enables measurement of oxygen utilization stoichiometry. We show that the redox exchange reaction is unaffected by side-chain modification whereas cyclization is dependent on both electronic and steric factors. In the light of these studies we conclude that the failure of tertiary amine-derived betaines to undergo redox exchange, and thus block in vitro activation of tyrosinase, is due to the absence of a second exchangeable proton.

  15. Diversity and distribution of catechol 2, 3-dioxygenase genes in surface sediments of the Bohai Sea.

    PubMed

    He, Peiqing; Li, Li; Liu, Jihua; Bai, Yazhi; Fang, Xisheng

    2016-05-01

    Catechol 2, 3-dioxygenase (C23O) is the key enzyme for aerobic aromatic degradation. Based on clone libraries and quantitative real-time polymerase chain reaction, we characterized diversity and distribution patterns of C23O genes in surface sediments of the Bohai Sea. The results showed that sediments of the Bohai Sea were dominated by genes related to C23O subfamily I.2.A. The samples from wastewater discharge area (DG) and aquaculture farm (KL) showed distinct composition of C23O genes when compared to the samples from Bohai Bay (BH), and total organic carbon was a crucial determinant accounted for the composition variation. C6BH12-38 and C2BH2-35 displayed the highest gene copies and highest ratios to the 16S rRNA genes in KL, and they might prefer biologically labile aromatic hydrocarbons via aquaculture inputs. Meanwhile, C7BH3-48 showed the highest gene copies and highest ratios to the 16S rRNA genes in DG, and this could be selective effect of organic loadings from wastewater discharge. An evident increase in C6BH12-38 and C7BH3-48 gene copies and reduction in diversity of C23O genes in DG and KL indicated composition perturbations of C23O genes and potential loss in functional redundancy. We suggest that ecological habitat and trophic specificity could shape the distribution of C23O genes in the Bohai Sea sediments. PMID:27190241

  16. Effects of Catechol-O-Methyltransferase on Normal Variation in the Cognitive Function of Children

    PubMed Central

    Barnett, Jennifer H.; Heron, Jon; Goldman, David; Jones, Peter B.; Xu, Ke

    2009-01-01

    Objective Genetic variants that contribute to the risk of psychiatric disorders may also affect normal variation in psychological function. Indeed, the behavioral effects of many genetic variants may be better understood as process-specific rather than disease-specific. A functional valine-to-methionine (Val158Met) polymorphism in the catechol-O-methyltransferase (COMT) gene has been associated with cognitive function and brain metabolic activity accompanying such tasks. Not all studies are consistent, and less is known about the effect of this polymorphism during development. The authors tested the hypothesis that a more informative COMT haplotype predicts normal cognitive development in a large population-based cohort of children enrolled in the Avon Longitudinal Study of Parents and children. Method Effects on verbal and performance IQ as well as verbal inhibition were assessed at age 8, and effects onworking memory were assessed at age 10. From the five COMT single nucleotide polymorphisms (SNPs) genotyped, the effect of a functional three-SNP haplotype consisting of Val158Met and two synonymous SNPs (rs6269 and rs4818), which together exert a major influence on the level of COMT expression and enzyme activity, was evaluated. Results This three-SNP haplotype predicted both verbal inhibition and working memory, and there was a genotype-by-sex interaction on verbal IQ. The effect of COMT genotype (diplotype) on cognition was curvilinear, which is consistent with the “inverted U” model of dopamine effect on frontal cortical efficiency. In addition, the SNP rs2075507 (previously rs2097603) was independently associatedwith verbal inhibition, while rs165599 showed no main cognitive effects. However, rs165599 showed a genotype-by-sex interaction with working memory. Conclusions Genetic variation at several loci in the COMT gene affects normal cognitive function in children. PMID:19605537

  17. Influence of catechol-O-methyltransferase (COMT) gene polymorphisms in pain sensibility of Brazilian fibromialgia patients.

    PubMed

    Barbosa, Flávia Regina; Matsuda, Josie Budag; Mazucato, Mendelson; de Castro França, Suzelei; Zingaretti, Sônia Marli; da Silva, Lucienir Maria; Martinez-Rossi, Nilce Maria; Júnior, Milton Faria; Marins, Mozart; Fachin, Ana Lúcia

    2012-02-01

    Fibromyalgia syndrome (FS) is a rheumatic syndrome affecting to 2-3% of individuals of productive age, mainly women. Neuroendocrine and genetic factors may play a significant role in development of the disease which is characterized by diffuse chronic pain and presence of tender points. Several studies have suggested an association between FS, especially pain sensitivity, and polymorphism of the catechol-O-methyltransferase (COMT) gene. The aim of the present study was to characterize the SNPs rs4680 and rs4818 of the COMT gene and assess its influence in pain sensitivity of patients with fibromyalgia screened by the Fibromyalgia Impact Questionnaire (FIQ). DNA was extracted from peripheral blood of 112 patients with fibromyalgia and 110 healthy individuals and was used as template in PCR for amplification of a 185-bp fragment of the COMT gene. The amplified fragment was sequenced for analyses of the SNPs rs4680 and rs4818. The frequency of mutant genotype AA of SNP rs6860 was 77.67% in patients with FS and 28.18% for the control group. For the SNP rs4818, the frequency of mutant genotype CC was 73.21 and 39.09% for patients with FS and controls, respectively. Moreover, the FIQ score was higher in patients with the homozygous mutant genotype for SNPs rs4680 (87.92 points) and rs4818 (86.14 points). These results suggest that SNPs rs4680 and rs4818 of the COMT gene may be associated with fibromyalgia and pain sensitivity in FS Brazilian patients.

  18. Effect of a natural mineral-rich water on catechol-O-methyltransferase function.

    PubMed

    Bastos, Pedro; Araújo, João Ricardo; Azevedo, Isabel; Martins, Maria João; Ribeiro, Laura

    2014-01-01

    Catechol-O-methyltransferase (COMT) is a magnesium-dependent, catecholamine-metabolizing enzyme, whose impaired activity has been positively associated with cardiovascular diseases, particularly hypertension. Consumption of some natural mineral-rich waters has been shown to exert protective effects on cardiovascular risk factors, eg. by decreasing arterial blood pressure and blood lipids. However, the molecular mechanisms underlying these effects are still poorly understood. So, the aim of this work was to investigate the effect of natural mineral-rich water ingestion upon liver and adrenal glands COMT expression and activity in Wistar Han rats. Over a seven-week period, animals had access to one of the following three drinking solutions: 1) tap water (control group; TW), 2) tap water with added Na(+) (to make the same concentration as in the MW group (TWNaCl group), or 3) natural mineral-rich water [Pedras Salgadas(®), which is very rich in bicarbonate, and with higher sodium, calcium and magnesium content than control tap water (MW group)]. COMT expression and activity were determined by RT-PCR and HPLC-ED, respectively. A higher hepatic COMT activity was found in the MW group compared with the TW and TWNaCl groups. On the other hand, adrenal gland COMT mRNA expression decreased in the MW group compared to TW group. In conclusion, the ability of natural mineral-rich waters to increase hepatic COMT activity may eventually explain the positive cardiovascular effects associated with the consumption of some natural mineral-rich waters.

  19. Breast Cancer Risk Reduction and Membrane-Bound Catechol O-Methyltransferase Genetic Polymorphisms

    PubMed Central

    Ji, Yuan; Olson, Janet; Zhang, Jianping; Hildebrandt, Michelle; Wang, Liewei; Ingle, James; Fredericksen, Zachary; Sellers, Thomas; Miller, William R.; Dixon, J. Michael; Brauch, Hiltrud; Eichelbaum, Michel; Justenhoven, Christina; Hamann, Ute; Ko, Yon; Brüning, Thomas; Chang-Claude, Jenny; Wang-Gohrke, Shan; Schaid, Daniel; Weinshilboum, Richard

    2008-01-01

    Catechol O-methyltransferase (COMT)-catalyzed methylation of catecholestrogens has been proposed to play a protective role in estrogen-induced genotoxic carcinogenesis. We have taken a comprehensive approach to test the hypothesis that genetic variation in COMT might influence breast cancer risk. Fifteen COMT SNPs selected on the basis of in-depth resequencing of the COMT gene were genotyped in 1482 DNA samples from a Mayo Clinic breast cancer case-control study. Two common SNPs in the distal promoter for membrane-bound (MB) COMT, rs2020917 and rs737865, were associated with breast cancer risk reduction in premenopausal women in the Mayo Clinic study, with allele-specific odds ratios of 0.70 (95% CI = 0.52–0.95) and 0.68 (95% CI = 0.51–0.92), respectively. These two SNPs were then subjected to functional genomic analysis and were genotyped in an additional 3683 DNA samples from two independent case-control studies (GENICA and GESBC). Functional genomic experiments showed that these SNPs could up-regulate transcription and that they altered DNA-protein binding patterns. Furthermore, substrate kinetic and exon array analyses suggested a role for MB-COMT in catecholestrogen inactivation. The GENICA results were similar to the Mayo case-control observations, with ORs of 0.85 (95% CI = 0.72–1.00) and 0.85 (95% CI = 0.72–1.01) for the two SNPs. No significant effect was observed in the GESBC study. These studies demonstrated that two SNPs in the COMT distal promoter were associated with breast cancer risk reduction in 2 of 3 case-control studies, compatible with the results of functional genomic experiments, suggesting a role for MB-COMT in breast cancer risk. PMID:18632656

  20. The Intracellular Pathogen Rhodococcus equi Produces a Catecholate Siderophore Required for Saprophytic Growth▿

    PubMed Central

    Miranda-CasoLuengo, Raúl; Prescott, John F.; Vázquez-Boland, José A.; Meijer, Wim G.

    2008-01-01

    Little is known about the iron acquisition systems of the soilborne facultative intracellular pathogen Rhodococcus equi. We previously reported that expression of iupABC, encoding a putative siderophore ABC transporter system, is iron regulated and required for growth at low iron concentrations. Here we show that disruption of iupA leads to the concomitant accumulation of catecholates and a chromophore with absorption maxima at 341 and 528 nm during growth under iron-replete conditions. In contrast, the wild-type strain produces these compounds only in iron-depleted medium. Disruption of iupU and iupS, encoding nonribosomal peptide synthetases, prevented growth of the corresponding R. equi SID1 and SID3 mutants at low iron concentrations. However, only R. equi SID3 did not produce the chromophore produced by the wild-type strain during growth at low iron concentrations. The phenotype of R. equi SID3, but not that of R. equi SID1, could be rescued by coculture with the wild type, allowing growth at low iron concentrations. This strongly suggests that the product of the iupS gene is responsible for the synthesis of a diffusible compound required for growth at low iron concentrations. Transcription of iupU was constitutive, but that of iupS was iron regulated, with an induction of 3 orders of magnitude during growth in iron-depleted compared to iron-replete medium. Neither mutant was attenuated in vivo in a mouse infection model, indicating that the iupU- and iupS-encoded iron acquisition systems are primarily involved in iron uptake during saprophytic life. PMID:18156254

  1. Molecular modeling and metabolic studies of the interaction of catechol-O-methyltransferase and a new nitrocatechol inhibitor.

    PubMed

    Palma, P N; Bonifácio, M J; Loureiro, A I; Wright, L C; Learmonth, D A; Soares-da-Silva, P

    2003-03-01

    Catechol-O-methyltransferase (COMT, EC 2.1.1.6) plays a central role in the metabolic inactivation of neurotransmitters and neuroactive xenobiotics possessing a catechol motif. 1-(3,4-Dihydroxy-5-nitrophenyl)-2-phenyl-ethanone (BIA 3-202) is a novel nitrocatechol-type inhibitor of COMT, the potential clinical benefit of which is currently being evaluated in the treatment of Parkinson's disease. In the present work we characterize the molecular interactions of BIA 3-202 within the active site of COMT and discuss their implication on the regioselectivity of metabolic O-methylation. Unrestrained flexible-docking simulations suggest that the solution structure of this complex is better described as an ensemble of alternative binding modes, in contrast to the well defined bound configuration revealed by the X-ray structures of related nitrocatechol inhibitors, co-crystallized with COMT. The docking results wherein presented are well supported by experimental evidence, where the pattern of in vitro enzymatic O-methylation and O-demethylation reactions are analyzed. We propose a plausible explanation for the paradoxical in vivo regioselectivity of O-methylation of BIA 3-202, as well as of its related COMT inhibitor tolcapone. Both compounds undergo in vivo O-methylation by COMT at either meta or para catechol hydroxyl groups. However, results herein presented suggest that, in a subsequent step, the p-O-methyl derivatives are selectively demethylated by a microsomal enzyme system. The overall balance is the accumulation of the m-O-methylated metabolites over the para-regioisomers. The implications for the general recognition of nitrocatechol-type inhibitors by COMT and the regioselectivity of their metabolic O-methylation are discussed.

  2. Five-coordinate M(II)-semiquinonate (M = Fe, Mn, Co) complexes: reactivity models of the catechol dioxygenases.

    PubMed

    Wang, Peng; Yap, Glenn P A; Riordan, Charles G

    2014-06-01

    A series of five-coordinate M(II)-semiquinonate (M = Fe, Mn, Co) complexes were synthesized and characterized, including the first example of a mononuclear Fe(II)-semiquinonate. Intermediates were observed in the reactions of M(II)-phenSQ (M = Fe, Co) with O2. Evidence for the relevance of these intermediates to the intradiol catechol dioxygenases was obtained by characterization of the oxidized semiquinone-derived product, muconic anhydride, resulting from the reaction of [PhTt(tBu)]Co(II)(3,5-DBSQ) with O2.

  3. Computationally-Guided Optimization of a Docking Hit to Yield Catechol Diethers as Potent Anti-HIV Agents

    PubMed Central

    Bollini, Mariela; Domaoal, Robert A.; Thakur, Vinay V.; Gallardo-Macias, Ricardo; Spasov, Krasimir A.; Anderson, Karen S.; Jorgensen, William L.

    2011-01-01

    A 5-μM docking hit has been optimized to an extraordinarily potent (55 pM) non-nucleoside inhibitor of HIV reverse transcriptase. Use of free energy perturbation (FEP) calculations to predict relative free energies of binding aided the optimizations by identifying optimal substitution patterns for phenyl rings and a linker. The most potent resultant catechol diethers feature terminal uracil and cyanovinylphenyl groups. A halogen bond with Pro95 likely contributes to the extreme potency of compound 42. In addition, several examples are provided illustrating failures of attempted grafting of a substructure from a very active compound onto a seemingly related scaffold to improve its activity. PMID:22081993

  4. The Role of Human Aldo-Keto Reductases in the Metabolic Activation and Detoxication of Polycyclic Aromatic Hydrocarbons: Interconversion of PAH Catechols and PAH o-Quinones.

    PubMed

    Zhang, Li; Jin, Yi; Huang, Meng; Penning, Trevor M

    2012-01-01

    Polycyclic aromatic hydrocarbons (PAH) are ubiquitous environmental pollutants. They are procarcinogens requiring metabolic activation to elicit their deleterious effects. Aldo-keto reductases (AKR) catalyze the oxidation of proximate carcinogenic PAH trans-dihydrodiols to yield electrophilic and redox-active PAH o-quinones. AKRs are also found to be capable of reducing PAH o-quinones to form PAH catechols. The interconversion of o-quinones and catechols results in the redox-cycling of PAH o-quinones to give rise to the generation of reactive oxygen species and subsequent oxidative DNA damage. On the other hand, PAH catechols can be intercepted through phase II metabolism by which PAH o-quinones could be detoxified and eliminated. The aim of the present review is to summarize the role of human AKRs in the metabolic activation/detoxication of PAH and the relevance of phase II conjugation reactions to human lung carcinogenesis.

  5. Homology modeling, simulation and molecular docking studies of catechol-2, 3-Dioxygenase from Burkholderia cepacia: Involved in degradation of Petroleum hydrocarbons.

    PubMed

    Ajao, At; Kannan, M; Yakubu, Se; Vj, Umoh; Jb, Ameh

    2012-01-01

    Catechol 2, 3-dioxygenase is present in several types of bacteria and undergoes degradation of environmental pollutants through an important key biochemical pathways. Specifically, this enzyme cleaves aromatic rings of several environmental pollutants such as toluene, xylene, naphthalene and biphenyl derivatives. Hence, the importance of Catechol 2, 3-dioxygenase and its role in the degradation of environmental pollutants made us to predict the three-dimensional structure of Catechol 2, 3-dioxygenase from Burkholderia cepacia. The 10ns molecular dynamics simulation was carried out to check the stability of the modeled Catechol 2, 3- dioxygenase. The results show that the model was energetically stable, and it attains their equilibrium within 2000 ps of production MD run. The docking of various petroleum hydrocarbons into the Catechol 2,3-dioxygenase reveals that the benzene, O-xylene, Toluene, Fluorene, Naphthalene, Carbazol, Pyrene, Dibenzothiophene, Anthracene, Phenanthrene, Biphenyl makes strong hydrogen bond and Van der waals interaction with the active site residues of H150, L152, W198, H206, H220, H252, I254, T255, Y261, E271, L276 and F309. Free energy of binding and estimated inhibition constant of these compounds demonstrates that they are energetically stable in their binding cavity. Chrysene shows positive energy of binding in the active site atom of Fe. Except Pyrene all the substrates made close contact with Fe atom by the distance ranges from 1.67 to 2.43 Å. In addition to that, the above mentioned substrate except pyrene all other made π-π stacking interaction with H252 by the distance ranges from 3.40 to 3.90 Å. All these docking results reveal that, except Chrysene all other substrate has good free energy of binding to hold enough in the active site and makes strong VdW interaction with Catechol-2,3-dioxygenase. These results suggest that, the enzyme is capable of catalyzing the above-mentioned substrate.

  6. Novel pathway for degradation of protocatechuic acid in Bacillus species.

    PubMed

    Crawford, R L

    1975-02-01

    A species of Bacillus, tentatively identified as B. circulans, degrades protocatechuic acid by a novel reaction involving meta-fission between C2 and C3 of the benzene nucleus. 2-Hydroxymuconic semialdehyde is then degraded to pyruvate and acetaldehyde by enzymatic reactions described in previous work. Protocatechuate 2,3-oxygenase exhibits a rather narrow substrate specificity; the methyl and ethyl esters of protocatechuic acid are oxidized, but other substrates for ring-fission oxygenases, notably catechol, gallic acid, and homoprotocatechuic acid, are not attached.

  7. Effects of Acute Dopamine Precusor Depletion on Immediate Reward Selection Bias and Working Memory Depend on Catechol-O-methyltransferase Genotype

    PubMed Central

    Kelm, Mary Katherine; Boettiger, Charlotte A.

    2013-01-01

    Little agreement exists as to acute dopamine (DA) manipulation effects on intertemporal choice in humans. We previously found that catechol-O-methyltransferase (COMT) Val158Met genotype predicts individual differences in immediate reward selection bias among adults. Moreover, we and others have shown that the relationship between COMT genotype and immediate reward bias is inverted in adolescents. No previous pharmacology studies testing DA manipulation effects on intertemporal choice have accounted for COMT genotype, and many have included participants in the adolescent age range (18–21) as adults. Moreover, many studies have included female subjects without strict cycle phase control, although recent evidence demonstrates that cyclic estradiol elevations interact with COMT genotype to affect DA-dependent cognition. These factors may have interacted with DA manipulations in past studies, potentially occluding detection of effects. Therefore, we predicted that among healthy adult males (ages 22–40), frontal DA tone, as indexed by COMT genotype, would interact with acute changes in DA signaling to affect intertemporal choice. In a double-blind, placebo-controlled design, we decreased central DA via administration of an amino acid beverage deficient in the DA precursors, phenylalanine and tyrosine (P/T[−]), and tested effects on immediate reward bias in a delay-discounting (DD) task and working memory (WM) in an n-back task. We found no main effect of beverage on DD or WM performance, but did find significant beverage*genotype effects. These results suggest that the effect of DA manipulations on DD depends on individual differences in frontal DA tone, which may have impeded some past efforts to characterize DA’s role in immediate reward bias in humans. PMID:23937688

  8. Bioavailability of phenanthrene in the presence of birnessite-mediated catechol polymers.

    PubMed

    Russo, Fabio; Rao, Maria A; Gianfreda, Liliana

    2005-07-01

    Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental contaminants and contribute to the pollution of aquatic and terrestrial environments. In soil, their fate may be affected by interactions with the soil biological community and soil colloids. This study was conducted to investigate the fate of phenanthrene (Phe), selected as a representative PAH, in simplified model systems, which simulate processes naturally occurring in soil. Phe was interacted with catechol (Cat), an orthodiphenol, and common intermediate in the microbial degradation of PAHs, and birnessite (Bir), an abiotic strong oxidative catalyst abundant in soil. Two experimental conditions were investigated: Cat (5 mM)+Bir (1 mg ml(-1))+Phe (0.05 mg ml(-1)) mixed at the same time and incubated for 24 h at 25 degrees C (Cat-Bir-Phe) and Cat+Bir incubated for 24 h at 25 degrees C before Phe addition and then incubated for a further 24 h (Cat-Bir+Phe). After incubation, the systems were analysed for residual Cat and Phe, supplied with a selected Phe-degrading mixed bacterial culture, and then the microbial degradation of Phe and the growth of cells were monitored. Complex phenomena simultaneously occurred. Cat was completely removed after a 24-h incubation with Bir, and no interference by Phe in the Bir-mediated transformation of Cat was observed. Elemental analysis and UV-Vis and Fourier transfer infrared spectra showed that Cat transformation by Bir produced soluble and insoluble polymeric aggregates involving Phe. The hydrocarbon also interacted with the surfaces of Bir either previously coated (Cat-Bir+Phe sample) or not by Cat polymers. When a Phe-degrading bacterial culture was added to the systems after Bir-mediated Cat polymerisation, a different behaviour was observed in terms of Phe consumption and bacterial growth, thus suggesting differentiated availability of Phe to the microbial cells. The hydrocarbon was completely transformed in the presence of Bir and/or Bir covered by Cat

  9. The studies of FT-IR and CD spectroscopy on catechol oxidase I from tobacco

    NASA Astrophysics Data System (ADS)

    Xiao, Hourong; Xie, Yongshu; Liu, Qingliang; Xu, Xiaolong; Shi, Chunhua

    2005-10-01

    A novel copper-containing enzyme named COI (catechol oxidase I) has been isolated and purified from tobacco by extracting acetone-emerged powder with phosphate buffer, centrifugation at low temperature, ammonium sulfate fractional precipitation, and column chromatography on DEAE-sephadex (A-50), sephadex (G-75), and DEAE-celluse (DE-52). PAGE, SDS-PAGE were used to detect the enzyme purity, and to determine its molecular weight. Then the secondary structures of COI at different pH, different temperatures and different concentrations of guanidine hydrochloride (GdnHCl) were studied by the FT-IR, Fourier self-deconvolution spectra, and circular dichroism (CD). At pH 2.0, the contents of both α-helix and anti-parallel β-sheet decrease, and that of random coil increases, while β-turn is unchanged compared with the neutral condition (pH 7.0). At pH 11.0, the results indicate that the contents of α-helix, anti-parallel β-sheet and β-turn decrease, while random coil structure increases. According to the CD measurements, the relative average fractions of α-helix, anti-parallel β-sheet, β-turn/parallel β-sheet, aromatic residues and disulfide bond, and random coil/γ-turn are 41.7%, 16.7%, 23.5%, 11.3%, and 6.8% at pH 7.0, respectively, while 7.2%, 7.7%, 15.2%, 10.7%, 59.2% at pH 2.0, and 20.6%, 9.5%, 15.2%, 10.5%, 44.2% at pH 11.0. Both α-helix and random coil decrease with temperature increasing, and anti-parallel β-sheet increases at the same time. After incubated in 6 mol/L guanidine hydrochloride for 30 min, the fraction of α-helix almost disappears (only 1.1% left), while random coil/γ-turn increases to 81.8%, which coincides well with the results obtained through enzymatic activity experiment.

  10. Polymorphisms in Catechol-O-methyltransferase Modify Treatment Effects of Aspirin on Risk of Cardiovascular Disease

    PubMed Central

    Hall, Kathryn T.; Nelson, Christopher P.; Davis, Roger B.; Buring, Julie E.; Kirsch, Irving; Mittleman, Murray A.; Loscalzo, Joseph; Samani, Nilesh J.; Ridker, Paul M; Kaptchuk, Ted J.; Chasman, Daniel I.

    2014-01-01

    Objective Catechol-O-methyltransferase (COMT), a key enzyme in catecholamine metabolism, is implicated in cardiovascular, sympathetic, and endocrine pathways. This study aimed to confirm preliminary association of COMT genetic variation with incident cardiovascular disease (CVD). It further aimed to evaluate whether aspirin, a commonly used CVD prevention agent, modified the potential association of COMT with incident CVD. Approach and Results We examined COMT polymorphism rs4680 (MAF=0.47), encoding a non-synonymous methionine (met)-to-valine (val) substitution, in the Women's Genome Health Study (WGHS), a large population-based cohort of women with randomized allocation to aspirin or vitamin E compared with placebo and 10 years follow-up. Rs4680 effects were confirmed with COMT polymorphism rs4818 and also examined in CARDIoGRAM/C4D, consortia for genome-wide association studies of coronary artery disease. Among WGHS women allocated to placebo (135 events/N=5811), the rs4680 val allele was protective against incident CVD relative to the met, (HR[95%CI]=0.66[0.51-0.84], p=0.0007); an association also observed in CARDIoGRAM and C4D (combined p=2.4×10-5). In the WGHS, the rs4680 association was abolished by randomized allocation to aspirin, such that val/val women experienced higher CVD rates with aspirin allocation compared to placebo (HR[95%CI]=1.85[1.05-3.25], p=0.033) while met/met women experienced lower rates (HR[95%CI]=0.60[0.39-0.93], p=0.023). Allocation to vitamin E also conferred higher but non-significant CVD rates on val/val (HR[95%CI]=1.50 [0.83-2.70], p=0.180) compared with significantly lower rates on met/met (HR[95%CI]=0.53[0.34-0.84], p=0.006) women. Rs4818 results were similar. Conclusions Common COMT polymorphisms were associated with incident CVD, and this association was modified by randomized allocation to aspirin or vitamin E. Replication of these findings is required. PMID:25035343

  11. Linking electrostatic effects and protein motions in enzymatic catalysis. A theoretical analysis of catechol o-methyltransferase.

    PubMed

    García-Meseguer, Rafael; Zinovjev, Kirill; Roca, Maite; Ruiz-Pernía, Javier J; Tuñón, Iñaki

    2015-01-22

    The role of protein motions in enzymatic catalysis is the subject of a hot scientific debate. We here propose the use of an explicit solvent coordinate to analyze the impact of environmental motions during the reaction process. The example analyzed here is the reaction catalyzed by catechol O-methyltransferase, a methyl transfer reaction from S-adenosylmethionine (SAM) to the nucleophilic oxygen atom of catecholate. This reaction proceeds from a charged reactant to a neutral product, and then a large electrostatic coupling with the environment could be expected. By means of a two-dimensional free energy surface, we show that a large fraction of the environmental motions needed to attain the transition state happens during the first stages of the reaction because most of the environmental motions are slower than changes in the substrate. The incorporation of the solvent coordinate in the definition of the transition state improves the transmission coefficient and the committor histogram in solution, while the changes are much less significant in the enzyme. The equilibrium solvation approach seems then to work better in the enzyme than in aqueous solution because the enzyme provides a preorganized environment where the reaction takes place.

  12. Tribological properties of self-assembled monolayers of catecholic imidazolium and the spin-coated films of ionic liquids.

    PubMed

    Liu, Jianxi; Li, Jinlong; Yu, Bo; Ma, Baodong; Zhu, Yangwen; Song, Xinwang; Cao, Xulong; Yang, Wu; Zhou, Feng

    2011-09-20

    A novel compound of an imidazolium type of ionic liquid (IL) containing a biomimetic catecholic functional group normally seen in mussel adhesive proteins was synthesized. The IL can be immobilized on a silicon surface and a variety of other engineering material surfaces via the catecholic anchor, allowing the tribological protection of these substrates for engineering applications. The surface wetting and adhesive properties and the tribological property of the synthesized self-assembled monolayers (SAMs) are successfully modulated by altering the counteranions. The chemical composition and wettability of the IL SAMs were characterized by means of X-ray photoelectron spectroscopy (XPS) and contact angle (CA) measurements. The adhesive and friction forces were measured with an atomic force microscope (AFM) on the nanometer scale. IL composite films were prepared by spin coating thin IL films on top of the SAMs. The macrotribological properties of these IL composite films were investigated with a pin-on-disk tribometer. The results indicate that the presence of IL SAMs on a surface can improve the wettability of spin-coated ionic liquids and thus the film quality and the tribological properties. These films registered a reduced friction coefficient and a significantly enhanced durability and load-carrying capacity. The tribological properties of the composite films are better than those of pure IL films because the presence of the monolayers improves the adhesion and compatibility of spin-coated IL films with substrates.

  13. The Influence of the Amide Linkage in the Fe(III) -Binding Properties of Catechol-Modified Rosamine Derivatives.

    PubMed

    Queirós, Carla; Leite, Andreia; G M Couto, Maria; Cunha-Silva, Luís; Barone, Giampaolo; de Castro, Baltazar; Rangel, Maria; M N Silva, André; M G Silva, Ana

    2015-10-26

    The two new fluorescent ligands RosCat1 and RosCat2 contain catechol receptors connected to rosamine platforms through an amide linkage and were synthesized by using microwave-assisted coupling reactions of carboxyl- or amine-substituted rosamines with the corresponding catechol units and subsequent deprotection. RosCat1 possesses a reverse amide, whereas RosCat2 has the usual oriented amide bond (HNCO vs. CONH, respectively). The ligands were characterized by means of NMR spectroscopy, mass-spectrometry, and DFT calculations and X-ray crystallography studies for RosCat1. The influence of the amide linkage on the photophysical properties of the fluorescent ligands was assessed in different solvents and showed a higher fluorescence quantum yield for RosCat1. The coordination chemistry of these ligands with a Fe(III) center has been rationalized by mass-spectrometric analysis and semiempirical calculations. Octahedral Fe(III) complexes were obtained by the chelation of three RosCat1 or RosCat2 ligands. Interestingly, the unconventional amide connectivity in RosCat1 imposes the formation of an eight-membered ring on the chelate complex through a "salicylate-type" mode of coordination.

  14. Construction of mussel-inspired coating via the direct reaction of catechol and polyethyleneimine for efficient heparin immobilization

    NASA Astrophysics Data System (ADS)

    Liu, Yujie; Luo, Rifang; Shen, Fangyu; Tang, Linlin; Wang, Jin; Huang, Nan

    2015-02-01

    Dopamine could self-polymerize to form the coating on various substrates and the co-existence of catechols and amines was crucial in performing such polymerization process. In this work, a mimetic approach of coating formation was carried out based on the co-polymerization of catechol (CA) and polyethyleneimine (PEI). Mussel-inspired CA/PEI coating was deposited on 316L stainless steel (SS). Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS) demonstrated the successful coating formation. QCM measurement showed good affinity of heparin immobilization on CA/PEI coating surface ascribed to the amine groups. Herein, vascular cell-material interactions like endothelial cells (ECs) and smooth muscle cells (SMCs) were also investigated. Interestingly, CA/PEI and heparin modified coatings presented no cytotoxicity to ECs, however to a certain extent, decreased SMCs proliferation. Moreover, heparin-binding surface presented significant anti-platelet adhesion and activation properties. These results effectively suggested that the mussel-inspired CA/PEI coating might be promising when served as a platform for biomolecule immobilization.

  15. Molecular-level spectroscopic investigations of the complexation and photodegradation of catechol to/by iron(III)

    NASA Astrophysics Data System (ADS)

    Al-Abadleh, Hind; Tofan-Lazar, Julia; Situm, Arthur; Slikboer, Samantha

    2014-05-01

    Surface water plays a crucial role in facilitating or inhibiting surface reactions in atmospheric aerosols. Little is known about the role of surface water in the complexation of organic molecules to transition metals in multicomponent aerosol systems. We will show results from real time diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments for the in situ complexation of catechol to Fe(III) and its photosensitized degradation under dry and humid conditions. Catechol was chosen as a simple model for humic-like substances (HULIS) in aerosols and aged polyaromatic hydrocarbons (PAH). It has also been detected in secondary organic aerosols (SOA) formed from the reaction of hydroxyl radicals with benzene. Given the importance of the iron content in aerosols and its biogeochemistry, our studies were conducted using FeCl3. For comparison, these surface-sensitive studies were complemented with bulk aqueous ATR-FTIR, UV-vis, and HPLC measurements for structural, quantitative and qualitative information about complexes in the bulk, and potential degradation products. The implications of our studies on understanding interfacial and condensed phase chemistry relevant to multicomponent aerosols, water thin islands on buildings, and ocean surfaces containing transition metals will be discussed.

  16. The Vibrio cholerae VctPDGC system transports catechol siderophores and a siderophore-free iron ligand.

    PubMed

    Wyckoff, Elizabeth E; Payne, Shelley M

    2011-09-01

    Vibrio cholerae, the causative agent of cholera, has an absolute requirement for iron. It transports the catechol siderophores vibriobactin, which it synthesizes and secretes, and enterobactin. These siderophores are transported across the inner membrane by one of two periplasmic binding protein-dependent ABC transporters, VctPDGC or ViuPDGC. We show here that one of these inner membrane transport systems, VctPDGC, also promotes iron acquisition in the absence of siderophores. Plasmids carrying the vctPDGC genes stimulated growth in both rich and minimal media of a Shigella flexneri mutant that produces no siderophores. vctPDGC also stimulated the growth of an Escherichia coli enterobactin biosynthetic mutant in low iron medium, and this effect did not require feoB, tonB or aroB. A tyrosine to phenylalanine substitution in the periplasmic binding protein VctP did not alter enterobactin transport, but eliminated growth stimulation in the absence of a siderophore. These data suggest that the VctPDGC system has the capacity to transport both catechol siderophores and a siderophore-free iron ligand. We also show that VctPDGC is the previously unidentified siderophore-independent iron transporter in V. cholerae, and this appears to complete the list of iron transport systems in V. cholerae.

  17. The Influence of the Amide Linkage in the Fe(III) -Binding Properties of Catechol-Modified Rosamine Derivatives.

    PubMed

    Queirós, Carla; Leite, Andreia; G M Couto, Maria; Cunha-Silva, Luís; Barone, Giampaolo; de Castro, Baltazar; Rangel, Maria; M N Silva, André; M G Silva, Ana

    2015-10-26

    The two new fluorescent ligands RosCat1 and RosCat2 contain catechol receptors connected to rosamine platforms through an amide linkage and were synthesized by using microwave-assisted coupling reactions of carboxyl- or amine-substituted rosamines with the corresponding catechol units and subsequent deprotection. RosCat1 possesses a reverse amide, whereas RosCat2 has the usual oriented amide bond (HNCO vs. CONH, respectively). The ligands were characterized by means of NMR spectroscopy, mass-spectrometry, and DFT calculations and X-ray crystallography studies for RosCat1. The influence of the amide linkage on the photophysical properties of the fluorescent ligands was assessed in different solvents and showed a higher fluorescence quantum yield for RosCat1. The coordination chemistry of these ligands with a Fe(III) center has been rationalized by mass-spectrometric analysis and semiempirical calculations. Octahedral Fe(III) complexes were obtained by the chelation of three RosCat1 or RosCat2 ligands. Interestingly, the unconventional amide connectivity in RosCat1 imposes the formation of an eight-membered ring on the chelate complex through a "salicylate-type" mode of coordination. PMID:26493881

  18. Significance of the Henri-Michaelis-Menten theory in abiotic catalysis: catechol oxidation by δ-MnO 2

    NASA Astrophysics Data System (ADS)

    Naidja, A.; Huang, P. M.

    2002-05-01

    The Henri-Michaelis-Menten theory, for more than eight decades, was only restricted to homogeneous enzymatic catalysis. A mimic of an enzymatic kinetics based on the Henri-Michaelis-Menten concept was experimentally observed in heterogeneous catalysis in the present study with δ-MnO 2 as an abiotic catalyst in the oxidation of catechol (1,2-dihydroxybenzene). Using the derived linear forms of Lineweaver-Burk or Hofstee, the data show that similar to the enzyme tyrosinase, the kinetics of the catechol oxidation catalyzed by δ-MnO 2 can be described by the Henri-Michaelis-Menten equation, V0= VmaxS/( Km+ S), where Vmax is the maximum velocity and Km the concentration of the substrate ( S) corresponding to an initial velocity ( V0) half of Vmax. By analogy to the enzymatic kinetics, the parameters Vmax and Km for an heterogeneous abiotic catalysis were derived for the first time. Further, based on the concentration of the active centers of the mineral oxide, the kinetic constants kcat and kcat/ Km, respectively, representing the turnover frequency and the efficiency of the mineral catalyst, were also determined from the derived general rate equation of Briggs and Haldane. As an abiotic catalyst, δ-MnO 2 has a paramount role in the oxidation of phenolic compounds in soil, sediment and water environments. Therefore, the present observation is of fundamental and practical significance in elucidating the affinity between an abiotic catalyst and a substrate based on the Henri-Michaelis-Menten theory.

  19. Synthesis, Evaluation of Anticancer Activity and QSAR Study of Heterocyclic Esters of Caffeic Acid

    PubMed Central

    Hajmohamad Ebrahim Ketabforoosh, Shima; Amini, Mohsen; Vosooghi, Mohsen; Shafiee, Abbas; Azizi, Ebrahim; Kobarfard, Farzad

    2013-01-01

    Caffeic acid phenethyl ester (CAPE) suppresses the growth of transformed cells such as human breast cancer cells, hepatocarcinoma , myeloid leukemia, colorectal cancer cells, fibrosarcoma, glioma and melanoma. A group of heterocyclic esters of caffeic acid was synthesized using Mitsunobu reaction and the esters were subjected to further structural modification by electrooxidation of the catechol ring of caffeic acid esters in the presence of sodium benzenesulfinate and sodium toluensulfinate as nucleophiles. Both heterocyclic esters of caffeic acid and their arylsulfonyl derivatives were evaluated for their cytotoxic activity against HeLa, SK-OV-3, and HT-29 cancer cell lines. HeLa cells showed the highest sensitivity to the compounds and heterocyclic esters with no substituent on catechol ring showed better activity compared to their substituted counterparts. QSAR studies reemphasized the importance of molecular shape of the compounds for their cytotoxic activity. PMID:24523750

  20. Neuraminidase inhibition of Dietary chlorogenic acids and derivatives - potential antivirals from dietary sources.

    PubMed

    Gamaleldin Elsadig Karar, Mohamed; Matei, Marius-Febi; Jaiswal, Rakesh; Illenberger, Susanne; Kuhnert, Nikolai

    2016-04-01

    Plants rich in chlorogenic acids (CGAs), caffeic acids and their derivatives have been found to exert antiviral effects against influenza virus neuroaminidase. In this study several dietary naturally occurring chlorogenic acids, phenolic acids and derivatives were screened for their inhibitory activity against neuroaminidases (NAs) from C. perfringens, H5N1 and recombinant H5N1 (N-His)-Tag using a fluorometric assay. There was no significant difference in inhibition between the different NA enzymes. The enzyme inhibition results indicated that chlorogenic acids and selected derivatives, exhibited high activities against NAs. It seems that the catechol group from caffeic acid was important for the activity. Dietary CGA therefore show promise as potential antiviral agents. However, caffeoyl quinic acids show low bioavailibility and are intensly metabolized by the gut micro flora, only low nM concentrations are observed in plasma and urine, therefore a systemic antiviral effect of these compounds is unlikely. Nevertheless, gut floral metabolites with a catechol moiety or structurally related dietary phenolics with a catechol moiety might serve as interesting compounds for future investigations. PMID:27010419

  1. Metabolism of the endocrine disruptor pesticide-methoxychlor by human P450s: pathways involving a novel catechol metabolite.

    PubMed

    Hu, Yiding; Kupfer, David

    2002-09-01

    The metabolism of methoxychlor, a proestrogenic pesticide (endocrine disruptor), was investigated with cDNA expressed human cytochrome P450s and liver microsomes (HLM). In addition to 1,1,1-trichloro-2-(4-hydroxyphenyl)-2-(4-methoxyphenyl)ethane (mono-OH-M), 1,1,1-trichloro-2, 2-bis(4-hydroxyphenyl)ethane (bis-OH-M), and 1,1,1-trichloro-2-(4-hydroxyphenyl)-2-(3, 4-dihydroxyphenyl)ethane (tris-OH-M), a new metabolite was identified as 1,1,1-trichloro-2-(4-methoxyphenyl)-2-(3, 4-dihydroxyphenyl)ethane (catechol-M; previously assumed to be ring-OH-M) and as a key metabolic intermediate. A novel metabolic route was proposed involving methoxychlor O-demethylation to mono-OH-M, followed by bifurcation of the pathway, both leading to the same final product tris-OH-M: pathway a, mono-OH-M is demethylated to bis-OH-M, followed by ortho-hydroxylation forming tris-OH-M and pathway b, mono-OH-M is ortho-hydroxylated forming catechol-M that is O-demethylated forming tris-OH-M. Among the human cDNA-expressed P450s examined, CYP1A2, 2A6, 2C8, 2C9, 2C19, and 2D6 exhibited mainly O-demethylation, with CYP2C19 being the most catalytically competent. CYP3A4, 3A5, and rat 2B1 catalyzed primarily ortho-hydroxylation of mono-OH-M (CYP3A4 being catalytically the most active) but were weak in O-demethylation. CYP1A1, 1B1, 2E1, and 4A11 demonstrated little or no catalytic activity. CYP2B6 appeared unique, catalyzing effectively both O-demethylation and ortho-hydroxylation. Thus, CYP2B6 demethylated methoxychlor to mono-OH-M and ortho-hydroxylated the mono-OH-M forming catechol-M; however, 2B6 did not appreciably demethylate mono-OH-M or ortho-hydroxylate bis-OH-M, suggesting a narrow substrate specificity. CYP2C19-catalyzed demethylation of methoxychlor, mono-OH-M and catechol-M, demonstrating relatively good substrate affinity (K(m) = 0.23 - 0.41 microM). However, the 3A4 ortho-hydroxylation of mono-OH-M and bis-OH-M exhibited lower affinity, K(m) = 12 and 25 microM, respectively. Thus, a

  2. The role of hydrogen bonding on the h-atom-donating abilities of catechols and naphthalene diols and on a previously overlooked aspect of their infrared spectra.

    PubMed

    Foti, Mario C; Barclay, L Ross C; Ingold, K U

    2002-10-30

    Catechols and 1,8-naphthalene diols contain one "free" hydroxyl and one intramolecularly H-bonded hydroxyl group. The "free" hydroxyls are strong hydrogen-bond donors (HBDs) with alpha2H values (Abraham et al. J. Chem. Soc., Perkin Trans. 2 1989, 699) ranging from 0.685 to 0.775, indicating that these compounds have similar HBD properties to those of strongly acidic phenols such as 4-chlorophenol (alpha2H = 0.670) and 3, 5-dichlorophenol (alpha2H = 0.774). Kinetic effects on H-atom abstractions from the diols in HB acceptor (HBA) solvents can be quantitatively accounted for over at least 50% of the available range of solvent HBA activities (as measured by their beta2H values; see Abraham et al. J. Chem. Soc. Perkin Trans. 2 1990, 521) on the basis of a single reactive OH group, the "free" OH. This free OH group is an outstanding H-atom donor in poor HBA solvents; e.g., in hexane rate constants for reaction with the DPPH* radical are 2.1 x 104 M-1 s-1 for 3,5-di-tert-butyl catechol and 2 x 106 M-1 s-1 for 4-methoxy-1,8-naphthalene diol, but only 7.4 x 103 M-1 s-1 for alpha-tocopherol (vitamin E). The diols are much more reactive than simple phenols because the O-H bond dissociation enthalpy of the "free" OH group is weakened by 5-9 kcal/mol by the intramolecular H-bond. The IR spectra of all the diols in CCl4 show two fairly sharp O-H stretching bands of roughly equal intensity separated by 42-138 cm-1. Addition of a low concentration of DMSO, a strong HBA, causes the band due to the intramolecularly H-bonded OH group to decrease in intensity to roughly half the extent that the "free" OH band loses intensity. The latter forms an intermolecular H-bond with the DMSO, the former does not. What has been overlooked in earlier work is that as the DMSO concentration is increased the band due to the intramolecularly H-bonded OH group first broadens and then evolves into a new, lower frequency (by 19-92 cm-1) band. The magnitude of the shift in the frequency of the

  3. Catechol degradation on hematite/silica-gas interface as affected by gas composition and the formation of environmentally persistent free radicals.

    PubMed

    Li, Hao; Guo, Huiying; Pan, Bo; Liao, Shaohua; Zhang, Di; Yang, Xikun; Min, Chungang; Xing, Baoshan

    2016-04-15

    Environmentally persistent free radicals (EPFRs) formed on a solid particle surface have received increasing attention because of their toxic effects. However, organic chemical fate regulated by EPFRs has rarely been investigated, and this information may provide the missing link in understanding their environmental behavior. Previous studies have suggested that the reduction of transition metals is involved in EPFRs formation. We thus hypothesize that an oxidative environment may inhibit EPFRs formation in particle-gas interface, which will consequently release free radicals and accelerate organic chemical degradation. Our result indicates that a 1% hematite coating on a silica surface inhibited catechol degradation in N2, especially at low catechol loadings on solid particles (SCT). However, under an O2 environment, catechol degradation decreased when SCT was <1 μg/mg but increased when SCT was >1 μg/mg. Stable organic free radicals were observed in the N2 system with g factors in the 2.0035-2.0050 range, suggesting the dominance of oxygen-centered free radicals. The introduction of O2 into the catechol degradation system substantially decreased the free radical signals and decreased the Fe(II) content. These results were observed in both dark and light irradiation systems, indicating the ubiquitous presence of EPFRs in regulating the fate of organic chemicals.

  4. Biochar, activated carbon, and carbon nanotubes have different effects on fate of 14C-catechol and microbial community in soil

    NASA Astrophysics Data System (ADS)

    Shan, Jun; Ji, Rong; Yu, Yongjie; Xie, Zubin; Yan, Xiaoyuan

    2015-10-01

    This study investigated the effects of biochar, activated carbon (AC)-, and single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs) in various concentrations (0, 0.2, 20, and 2,000 mg/kg dry soil) on the fate of 14C-catechol and microbial community in soil. The results showed that biochar had no effect on the mineralization of 14C-catechol, whereas AC at all amendment rates and SWCNTs at 2,000 mg/kg significantly reduced mineralization. Particularly, MWCNTs at 0.2 mg/kg significantly stimulated mineralization compared with the control soil. The inhibitory effects of AC and SWCNTs on the mineralization were attributed to the inhibited soil microbial activities and the shifts in microbial communities, as suggested by the reduced microbial biomass C and the separated phylogenetic distance. In contrast, the stimulatory effects of MWCNTs on the mineralization were attributed to the selective stimulation of specific catechol-degraders by MWCNTs at 0.2 mg/kg. Only MWCNTs amendments and AC at 2,000 mg/kg significantly changed the distribution of 14C residues within the fractions of humic substances. Our findings suggest biochar, AC, SWCNTs and MWCNTs have different effects on the fate of 14C-catechol and microbial community in soil.

  5. Receptor for catecholamines responding to catechol which potentiates voltage-dependent calcium current in single cells from guinea-pig taenia caeci.

    PubMed Central

    Muraki, K.; Bolton, T. B.; Imaizumi, Y.; Watanabe, M.

    1994-01-01

    1. Single isolated cells were obtained from the taenia of the guinea-pig's caecum by enzymic digestion and held under voltage clamp. The effects of various catecholamines, sympathomimetics and related compounds were tested for their ability to potentiate the voltage-dependent calcium current (ICa) evoked in these cells by a depolarizing step. 2. ICa was potentiated by up to 60% by isoprenaline, adrenaline, and noradrenaline which were equipotent. The EC50 for isoprenaline was about 40 nM. 3. The racemic mixtures of the optical isomers of isoprenaline, adrenaline, and noradrenaline, and (+)-isoprenaline, were equipotent with the (-)-isomers of these drugs. Dopamine, L-dopa, and catechol were equipotent with these catecholamines. 4. Removal or substitution of one or more of the hydroxy groups of the catechol moiety, as in phenylephrine, salbutamol, procaterol, methoxamine, terbutaline, BRL 37344, ICI 215001 or tyramine substantially reduced efficacy and/or potency. 5. The adrenoceptor blockers propranolol, phentolamine, dihydroergotamine, atenolol, CGP 20712A and ICI 118551, or the dopamine receptor blockers, haloperidol or flupenthixol, did not block the potentiating action of catechol or the catecholamines. 6. The receptor activated by catecholamines to increase ICa we suggest should be called a C-receptor in view of its sensitivity to catechol. It may arise by enzymic modification of a conventional adrenoceptor but its transduction also involves a novel mechanism which might indicate that it is present in the muscle cells before enzyme treatment. PMID:8032602

  6. Catechol degradation on hematite/silica-gas interface as affected by gas composition and the formation of environmentally persistent free radicals

    NASA Astrophysics Data System (ADS)

    Li, Hao; Guo, Huiying; Pan, Bo; Liao, Shaohua; Zhang, Di; Yang, Xikun; Min, Chungang; Xing, Baoshan

    2016-04-01

    Environmentally persistent free radicals (EPFRs) formed on a solid particle surface have received increasing attention because of their toxic effects. However, organic chemical fate regulated by EPFRs has rarely been investigated, and this information may provide the missing link in understanding their environmental behavior. Previous studies have suggested that the reduction of transition metals is involved in EPFRs formation. We thus hypothesize that an oxidative environment may inhibit EPFRs formation in particle-gas interface, which will consequently release free radicals and accelerate organic chemical degradation. Our result indicates that a 1% hematite coating on a silica surface inhibited catechol degradation in N2, especially at low catechol loadings on solid particles (SCT). However, under an O2 environment, catechol degradation decreased when SCT was <1 μg/mg but increased when SCT was >1 μg/mg. Stable organic free radicals were observed in the N2 system with g factors in the 2.0035-2.0050 range, suggesting the dominance of oxygen-centered free radicals. The introduction of O2 into the catechol degradation system substantially decreased the free radical signals and decreased the Fe(II) content. These results were observed in both dark and light irradiation systems, indicating the ubiquitous presence of EPFRs in regulating the fate of organic chemicals.

  7. Catechol-O-Methyltransferase "Val[superscript 158]Met" Genotype, Parenting Practices and Adolescent Alcohol Use: Testing the Differential Susceptibility Hypothesis

    ERIC Educational Resources Information Center

    Laucht, Manfred; Blomeyer, Dorothea; Buchmann, Arlette F.; Treutlein, Jens; Schmidt, Martin H.; Esser, Gunter; Jennen-Steinmetz, Christine; Rietschel, Marcella; Zimmermann, Ulrich S.; Banaschewski, Tobias

    2012-01-01

    Background: Recently, first evidence has been reported for a gene-parenting interaction (G x E) with regard to adolescent alcohol use. The present investigation set out to extend this research using the catechol-O-methyltransferase ("COMT") "Val[superscript 158]Met" polymorphism as a genetic susceptibility factor. Moreover, the current study…

  8. Catechol degradation on hematite/silica–gas interface as affected by gas composition and the formation of environmentally persistent free radicals

    PubMed Central

    Li, Hao; Guo, Huiying; Pan, Bo; Liao, Shaohua; Zhang, Di; Yang, Xikun; Min, Chungang; Xing, Baoshan

    2016-01-01

    Environmentally persistent free radicals (EPFRs) formed on a solid particle surface have received increasing attention because of their toxic effects. However, organic chemical fate regulated by EPFRs has rarely been investigated, and this information may provide the missing link in understanding their environmental behavior. Previous studies have suggested that the reduction of transition metals is involved in EPFRs formation. We thus hypothesize that an oxidative environment may inhibit EPFRs formation in particle-gas interface, which will consequently release free radicals and accelerate organic chemical degradation. Our result indicates that a 1% hematite coating on a silica surface inhibited catechol degradation in N2, especially at low catechol loadings on solid particles (SCT). However, under an O2 environment, catechol degradation decreased when SCT was <1 μg/mg but increased when SCT was >1 μg/mg. Stable organic free radicals were observed in the N2 system with g factors in the 2.0035–2.0050 range, suggesting the dominance of oxygen-centered free radicals. The introduction of O2 into the catechol degradation system substantially decreased the free radical signals and decreased the Fe(II) content. These results were observed in both dark and light irradiation systems, indicating the ubiquitous presence of EPFRs in regulating the fate of organic chemicals. PMID:27079263

  9. Biochar, activated carbon, and carbon nanotubes have different effects on fate of 14C-catechol and microbial community in soil

    PubMed Central

    Shan, Jun; Ji, Rong; Yu, Yongjie; Xie, Zubin; Yan, Xiaoyuan

    2015-01-01

    This study investigated the effects of biochar, activated carbon (AC)-, and single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs) in various concentrations (0, 0.2, 20, and 2,000 mg/kg dry soil) on the fate of 14C-catechol and microbial community in soil. The results showed that biochar had no effect on the mineralization of 14C-catechol, whereas AC at all amendment rates and SWCNTs at 2,000 mg/kg significantly reduced mineralization. Particularly, MWCNTs at 0.2 mg/kg significantly stimulated mineralization compared with the control soil. The inhibitory effects of AC and SWCNTs on the mineralization were attributed to the inhibited soil microbial activities and the shifts in microbial communities, as suggested by the reduced microbial biomass C and the separated phylogenetic distance. In contrast, the stimulatory effects of MWCNTs on the mineralization were attributed to the selective stimulation of specific catechol-degraders by MWCNTs at 0.2 mg/kg. Only MWCNTs amendments and AC at 2,000 mg/kg significantly changed the distribution of 14C residues within the fractions of humic substances. Our findings suggest biochar, AC, SWCNTs and MWCNTs have different effects on the fate of 14C-catechol and microbial community in soil. PMID:26515132

  10. Degradation and COD removal of catechol in wastewater using the catalytic ozonation process combined with the cyclic rotating-bed biological reactor.

    PubMed

    Aghapour, Ali Ahmad; Moussavi, Gholamreza; Yaghmaeian, Kamyar

    2015-07-01

    The effect of ozonation catalyzed with MgO/granular activated carbon (MgO/GAC) composite as a pretreatment process on the performance of cyclic rotating-bed biological reactor (CRBR) for the catechol removal from wastewater has been investigated. CRBR with acclimated biomasses could efficiently remove catechol and its related COD from wastewater at organic loading rate (OLR) of 7.82 kg COD/m(3).d (HRT of 9 h). Then, OLR increased to 15.64 kg COD/m(3).d (HRT of 4.5 h) and CRBR failed. Catalytic ozonation process (COP) used as a pre-treatment and could improve the performance of the failed CRBR. The overall removal efficiency of the combined process attained respective steady states of 91% and 79% for degradation and COD removal of catechol. Therefore, the combined process is more effective in degradation and COD removal of catechol; it is also a viable alternative for upgrading industrial wastewater treatment plant.

  11. Catechol siderophores repress the pyochelin pathway and activate the enterobactin pathway in Pseudomonas aeruginosa: an opportunity for siderophore-antibiotic conjugates development.

    PubMed

    Gasser, Véronique; Baco, Etienne; Cunrath, Olivier; August, Pamela Saint; Perraud, Quentin; Zill, Nicolas; Schleberger, Christian; Schmidt, Alexander; Paulen, Aurélie; Bumann, Dirk; Mislin, Gaëtan L A; Schalk, Isabelle J

    2016-03-01

    Previous studies have suggested that antibiotic vectorization by siderophores (iron chelators produced by bacteria) considerably increases the efficacy of such drugs. The siderophore serves as a vector: when the pathogen tries to take up iron via the siderophore, it also takes up the antibiotic. Catecholates are among the most common iron-chelating compounds used in synthetic siderophore-antibiotic conjugates. Using reverse transcription polymerase chain reaction and proteomic approaches, we showed that the presence of catecholate compounds in the medium of Pseudomonas aeruginosa led to strong activation of the transcription and expression of the outer membrane transporter PfeA, the ferri-enterobactin importer. Iron-55 uptake assays on bacteria with and without PfeA expression confirmed that catechol compounds imported iron into P. aeruginosa cells via PfeA. Uptake rates were between 0.3 × 10(3) and 2 × 10(3) Fe atoms/bacterium/min according to the used catechol siderophore in iron-restricted medium, and remained as high as 0.8 × 10(3) Fe atoms/bacterium/min for enterobactin, even in iron-rich medium. Reverse transcription polymerase chain reaction and proteomic approaches showed that in parallel to this switching on of PfeA expression, a repression of the expression of pyochelin (PCH) pathway genes (PCH being one of the two siderophores produced by P. aeruginosa for iron acquisition) was observed. PMID:26718479

  12. Biochar, activated carbon, and carbon nanotubes have different effects on fate of (14)C-catechol and microbial community in soil.

    PubMed

    Shan, Jun; Ji, Rong; Yu, Yongjie; Xie, Zubin; Yan, Xiaoyuan

    2015-10-30

    This study investigated the effects of biochar, activated carbon (AC)-, and single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs) in various concentrations (0, 0.2, 20, and 2,000 mg/kg dry soil) on the fate of (14)C-catechol and microbial community in soil. The results showed that biochar had no effect on the mineralization of (14)C-catechol, whereas AC at all amendment rates and SWCNTs at 2,000 mg/kg significantly reduced mineralization. Particularly, MWCNTs at 0.2 mg/kg significantly stimulated mineralization compared with the control soil. The inhibitory effects of AC and SWCNTs on the mineralization were attributed to the inhibited soil microbial activities and the shifts in microbial communities, as suggested by the reduced microbial biomass C and the separated phylogenetic distance. In contrast, the stimulatory effects of MWCNTs on the mineralization were attributed to the selective stimulation of specific catechol-degraders by MWCNTs at 0.2 mg/kg. Only MWCNTs amendments and AC at 2,000 mg/kg significantly changed the distribution of (14)C residues within the fractions of humic substances. Our findings suggest biochar, AC, SWCNTs and MWCNTs have different effects on the fate of (14)C-catechol and microbial community in soil.

  13. Metabolite Profiles of Lactic Acid Bacteria in Grass Silage▿

    PubMed Central

    Broberg, Anders; Jacobsson, Karin; Ström, Katrin; Schnürer, Johan

    2007-01-01

    The metabolite production of lactic acid bacteria (LAB) on silage was investigated. The aim was to compare the production of antifungal metabolites in silage with the production in liquid cultures previously studied in our laboratory. The following metabolites were found to be present at elevated concentrations in silos inoculated with LAB strains: 3-hydroxydecanoic acid, 2-hydroxy-4-methylpentanoic acid, benzoic acid, catechol, hydrocinnamic acid, salicylic acid, 3-phenyllactic acid, 4-hydroxybenzoic acid, (trans, trans)-3,4-dihydroxycyclohexane-1-carboxylic acid, p-hydrocoumaric acid, vanillic acid, azelaic acid, hydroferulic acid, p-coumaric acid, hydrocaffeic acid, ferulic acid, and caffeic acid. Among these metabolites, the antifungal compounds 3-phenyllactic acid and 3-hydroxydecanoic acid were previously isolated in our laboratory from liquid cultures of the same LAB strains by bioassay-guided fractionation. It was concluded that other metabolites, e.g., p-hydrocoumaric acid, hydroferulic acid, and p-coumaric acid, were released from the grass by the added LAB strains. The antifungal activities of the identified metabolites in 100 mM lactic acid were investigated. The MICs against Pichia anomala, Penicillium roqueforti, and Aspergillus fumigatus were determined, and 3-hydroxydecanoic acid showed the lowest MIC (0.1 mg ml−1 for two of the three test organisms). PMID:17616609

  14. Synthesis and characterization of chromium(III) Schiff base complexes: antimicrobial activity and its electrocatalytic sensing ability of catechol.

    PubMed

    Kumar, S Praveen; Suresh, R; Giribabu, K; Manigandan, R; Munusamy, S; Muthamizh, S; Narayanan, V

    2015-03-15

    A series of acyclic Schiff base chromium(III) complexes were synthesized with the aid of microwave irradiation method. The complexes were characterized on the basis of elemental analysis, spectral analysis such as UV-Visible, Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR) spectroscopies and electrospray ionization (ESI) mass spectrometry. Electrochemical analysis of the complexes indicates the presence of chromium ion in +3 oxidation state. Cr (III) ion is stabilized by the tetradentate Schiff base ligand through its nitrogen and phenolic oxygen. From the spectral studies it is understood that the synthesized chromium(III) complexes exhibits octahedral geometry. Antimicrobial activity of chromium complexes was investigated towards the Gram positive and Gram negative bacteria. In the present work, an attempt was made to fabricate a new kind of modified electrode based on chromium Schiff base complexes for the detection of catechol at nanomolar level.

  15. Biochemical and spectroscopic characterization of catechol oxidase from sweet potatoes (Ipomoea batatas) containing a type-3 dicopper center.

    PubMed

    Eicken, C; Zippel, F; Büldt-Karentzopoulos, K; Krebs, B

    1998-10-01

    Two catechol oxidases have been isolated from sweet potatoes (Ipomoea batatas) and purified to homogeneity. The two isozymes have been characterized by EXAFS, EPR-, UV/Vis-spectroscopy, isoelectric focusing, and MALDI-MS and have been shown to contain a dinuclear copper center. Both are monomers with a molecular mass of 39 kDa and 40 kDa, respectively. Substrate specificity and NH2-terminal sequences have been determined. EXAFS data for the 39 kDa enzyme reveal a coordination number of four for each Cu in the resting form and suggest a Cu(II)-Cu(II) distance of 2.9 A for the native met form and 3.8 A for the oxy form.

  16. Biochemical and spectroscopic characterization of catechol oxidase from sweet potatoes (Ipomoea batatas) containing a type-3 dicopper center.

    PubMed

    Eicken, C; Zippel, F; Büldt-Karentzopoulos, K; Krebs, B

    1998-10-01

    Two catechol oxidases have been isolated from sweet potatoes (Ipomoea batatas) and purified to homogeneity. The two isozymes have been characterized by EXAFS, EPR-, UV/Vis-spectroscopy, isoelectric focusing, and MALDI-MS and have been shown to contain a dinuclear copper center. Both are monomers with a molecular mass of 39 kDa and 40 kDa, respectively. Substrate specificity and NH2-terminal sequences have been determined. EXAFS data for the 39 kDa enzyme reveal a coordination number of four for each Cu in the resting form and suggest a Cu(II)-Cu(II) distance of 2.9 A for the native met form and 3.8 A for the oxy form. PMID:9781698

  17. Effect of Substituents in Catechol Dye Sensitizers on Photovoltaic Performance of Type II Dye-Sensitized Solar Cells.

    PubMed

    Ooyama, Yousuke; Kanda, Masahiro; Uenaka, Koji; Ohshita, Joji

    2015-10-01

    In order to provide a direction in molecular design of catechol (Cat) dyes for type II dye-sensitized solar cells (DSSCs), the dye-to-TiO2 charge-transfer (DTCT) characteristics of Cat dyes with various substituents and their photovoltaic performance in DSSCs are investigated. The Cat dyes with electron-donating or moderately electron-withdrawing substituents exhibit a broad absorption band corresponding to DTCT upon binding to TiO2 films, whereas those with strongly electron-withdrawing substituents exhibit weak DTCT. This study indicates that the introduction of a moderately electron-withdrawing substituent on the Cat moiety leads to not only an increase in the DTCT efficiency, but also the retardation of back electron transfer. This results in favorable conditions for the type II electron-injection pathway from the ground state of the Cat dye to the conduction band of the TiO2 electrode by the photoexcitation of DTCT bands.

  18. Theoretical study of the Pb(II)-catechol system in dilute aqueous solution: Complex structure and metal coordination sphere determination

    NASA Astrophysics Data System (ADS)

    Lapouge, Christine; Cornard, Jean-Paul

    2010-04-01

    We investigated the unknown interaction of Pb(II) with catechol ligand in diluted aqueous solution by electronic spectroscopies combined with quantum chemical calculations. The aim of this work is the determination of the complete structure of the complex formed and particularly the metal coordination sphere. Three successive steps have been necessary to reach this goal: (i) the comparison of the experimental electronic absorption spectrum with theoretical spectra calculated from various hypothetical structures, (ii) complexation reaction pathways calculations in vacuum and with taking into account the solvent effects and finally (iii) the fluorescence emission wavelength calculations. All these investigations led to identify a monodentate complex with the monodeprotonated ligand, in which the Pb atom presents a coordination number of five. The formula of the complex is [Pb(Hcat)(HO)4]mono+.

  19. Self-assembly of a catechol-based macrocycle at the liquid-solid interface: experiments and molecular dynamics simulations.

    PubMed

    Saiz-Poseu, Javier; Martínez-Otero, Alberto; Roussel, Thomas; Hui, Joseph K-H; Montero, Mavis L; Urcuyo, Roberto; MacLachlan, Mark J; Faraudo, Jordi; Ruiz-Molina, Daniel

    2012-09-14

    This combined experimental (STM, XPS) and molecular dynamics simulation study highlights the complex and subtle interplay of solvent effects and surface interactions on the 2-D self-assembly pattern of a Schiff-base macrocycle containing catechol moieties at the liquid-solid interface. STM imaging reveals a hexagonal ordering of the macrocycles at the n-tetradecane/Au(111) interface, compatible with a desorption of the lateral chains of the macrocycle. Interestingly, all the triangular-shaped macrocycles are oriented in the same direction, avoiding a close-packed structure. XPS experiments indicate the presence of a strong macrocycle-surface interaction. Also, MD simulations reveal substantial solvent effects. In particular, we find that co-adsorption of solvent molecules with the macrocycles induces desorption of lateral chains, and the solvent molecules act as spacers stabilizing the open self-assembly pattern. PMID:22847275

  20. Purification and Characterization of Catechol 1,2-Dioxygenase from Acinetobacter sp. Y64 Strain and Escherichia coli Transformants.

    PubMed

    Lin, J; Milase, R N

    2015-12-01

    This study intends to purify and characterize catechol 1,2-dioxygenase (C1,2O) of phenol-degrading Acinetobacter sp. Y64 and of E. coli transformant. Acinetobacter sp. Y64 was capable of degrading 1000 mg/L of phenol within 14 ± 2 h at 30 °C, 160 rpm and pH of 7. One C1,2O of 36 kDa was purified using ammonium sulphate precipitation and Hitrap QFF column chromatograph with 49% recovery and a 10.6-fold increase in purity. Purified Y64 C1,2O had temperature and pH optimum at 37 °C and pH 7.7 respectively with the Michaelis constant of 17.53 µM and the maximal velocity of 1.95 U/mg, respectively. The presence of Fe(3+) or Fe(2+) enhanced the activity of Y64 C1,2O while other compounds such as Ca(2+), and EDTA had an inhibitory effect. 80% of C1,2O activity remained using 4-nitrocatechol as substrate while 2% remained using 3-methylcatechol compared with that using catechol. Y64 catA gene encoding C1,2O was amplified using PCR cloned into pET22b vector and expressed in Escherichia coli BL21 DE3 (pLysS) after transformation. Purified and cloned Y64 C1,2O show no significant differences in the biochemical properties. The phylogenetic tree based on the protein sequences indicates that these C1,2Os possess a common ancestry.

  1. Darkening mechanism and kinetics of humification process in catechol-Maillard system.

    PubMed

    Zhang, Yingchao; Yue, Dongbei; Ma, Hong

    2015-07-01

    Humic acids, products of humification process, are capable of interacting with contaminants and can be applied to environmental remediation. Browning mechanisms of humification is critical to understand and further control the process. This study aimed to investigate the mechanism of abiotic humification by tracking the fate of the precursors in systems containing glucose, glycine, and various CT concentrations, which were promoted by MnO2. Results show that the N-containing organic molecules significantly contributed in controlling the darkening effect. Increasing CT promoted the formation of Fulvic-like acids (FLAs) and Humic-like acids (HLAs). The entire reaction could be divided into two steps following pseudo-second-order kinetics equation and pseudo-zero-order kinetics equation. Moreover, increasing CT contributed to the increase of the degree of unsaturation in HLAs. PMID:25770693

  2. Observation of UV-induced Auger features in catechol adsorbed on anatase TiO{sub 2} (101) single crystal surface

    SciTech Connect

    Thomas, Andrew G.; Syres, Karen L.

    2012-04-23

    We have investigated the electronic structure of catechol adsorbed on the anatase TiO{sub 2} (101) surface under illumination with ultraviolet (UV) light (4.75 eV) using resonant photoemission spectroscopy. UV illumination results in the appearance of a strong Ti MVV (M refers to photoionization of 3p level and VV the Auger decay process via the valence levels) feature at a kinetic energy of 26.2 eV. This is attributed to the creation of localised states following catechol to Ti-3d excitation by the UV source. A sharp resonance attributed to excitation from Ti 3p states into these localised states is observed in constant final state spectra.

  3. Formation of environmentally persistent free radicals as the mechanism for reduced catechol degradation on hematite-silica surface under UV irradiation.

    PubMed

    Li, Hao; Pan, Bo; Liao, Shaohua; Zhang, Di; Xing, Baoshan

    2014-05-01

    Iron is rich in soils, and is recently reported to form stable complexes with organic free radicals, generating environmentally persistent free radicals (EPFRs). The observation may challenge the common viewpoint that iron is an effective catalyst to facilitate the degradation of various organic chemicals. But no study was specifically designed to investigate the possible inhibited degradation of organic chemicals because of the formation of EPFRs in dry environment. We observed that catechol degradation under UV irradiation was decreased over 20% in silica particles coated with 1% hematite in comparison to uncoated silica particles. Stabilized semiquinone or quinine and phenol radicals were involved in HMT-silica system. EPFR formation was thus the reason for the reduced catechol degradation on HMT-silica surface under UV irradiation at ambient temperature. EPFRs should be incorporated in the studies of organic contaminants geochemical behavior, and will be a new input in their environmental fate modeling.

  4. Theoretical modeling of enzyme catalytic power: analysis of "cratic" and electrostatic factors in catechol O-methyltransferase.

    PubMed

    Roca, Maite; Martí, Sergio; Andrés, Juan; Moliner, Vicent; Tuñón, Iñaki; Bertrán, Juan; Williams, Ian H

    2003-06-25

    A comparative theoretical study of a bimolecular reaction in aqueous solution and catalyzed by the enzyme catechol O-methyltransferase (COMT) has been carried out by a combination of two hybrid QM/MM techniques: statistical simulation methods and internal energy minimizations. In contrast to previous studies by other workers, we have located and characterized transition structures for the reaction in the enzyme active site, in water and in a vacuum, and our potential of mean force calculations are based upon reaction coordinates obtained from features of the potential energy surfaces in the condensed media, not from the gas phase. The AM1/CHARMM calculated free energy of activation for the reaction of S-adenosyl methionine (SAM) with catecholate catalyzed by COMT is 15 kcal mol(-1) lower the AM1/TIP3P free-energy barrier for the reaction of the trimethylsulfonium cation with the catecholate anion in water at 300 K, in agreement with previous estimates. The thermodynamically preferred form of the reactants in the uncatalyzed model reaction in water is a solvent-separated ion pair (SSIP). Conversion of the SSIP into a contact ion pair, with a structure resembling that of the Michaelis complex (MC) for the reaction in the COMT active site, is unfavorable by 7 kcal mol(-1), largely due to reorganization of the solvent. We have considered alternative ways to estimate the so-called "cratic" free energy for bringing the reactant species together in the correct orientation for reaction but conclude that direct evaluation of the free energy of association by means of molecular dynamics simulation with a simple standard-state correction is probably the best approach. The latter correction allows for the fact that the size of the unit cell employed with the periodic boundary simulations does not correspond to the standard state concentration of 1 M. Consideration of MC-like species allows a helpful decomposition of the catalytic effect into preorganization and reorganization

  5. Sensitization of nanocrystalline TiO2 anchored with pendant catechol functionality using a new tetracyanato ruthenium(II) polypyridyl complex.

    PubMed

    Kar, Prasenjit; Verma, Sandeep; Sen, Anik; Das, Amitava; Ganguly, Bishwajit; Ghosh, Hirendra Nath

    2010-05-01

    We have synthesized a new photoactive ruthenium(II) complex having a pendant catechol functionality (K(2)[Ru(CN)(4)(L)] (1) (L is 4-[2-(4'-methyl-2,2'-bipyridinyl-4-yl)vinyl]benzene-1,2-diol) for studying the dynamics of the interfacial electron transfer between nanoparticulate TiO(2) and the photoexcited states of this Ru(II) complex using femtosecond transient absorption spectroscopy. Steady-state absorption and emission studies revealed that the complex 1 showed a strong solvatochromic behavior in solvents or solvent mixtures of varying polarity. Our steady-state absorption studies further revealed that 1 is bound to TiO(2) surfaces through the catechol functionality, though 1 has two different types of functionalities (catecholate and cyanato) for binding to TiO(2) surfaces. The longer wavelength absorption band tail for 1, bound to TiO(2) through the proposed catecholate functionality, could also be explained on the basis of the DFT calculations. Dynamics of the interfacial electron transfer between 1 and TiO(2) nanoparticles was investigated by studying kinetics at various wavelengths in the visible and near-infrared region. Electron injection to the conduction band of the nanoparticulate TiO(2) was confirmed by detection of the conduction band electron in TiO(2) ([e(-)](TiO(2))(CB)) and cation radical of the adsorbed dye (1(*+)) in real time as monitored by transient absorption spectroscopy. A single exponential and pulse-width limited (<100 fs) electron injection was observed. Back electron transfer dynamics was determined by monitoring the decay kinetics of 1(*+) and [e(-)](TiO(2))(CB). This is the first report on ultrafast ET dynamics on TiO(2) nanoparticle surface using a solvatochromic sensitizer molecule.

  6. Laccase-catalyzed domino reaction between catechols and 6-substituted 1,2,3,4-tetrahydro-4-oxo-2-thioxo-5-pyrimidinecarbonitriles for the synthesis of pyrimidobenzothiazole derivatives.

    PubMed

    Abdel-Mohsen, Heba T; Conrad, Jürgen; Beifuss, Uwe

    2013-08-16

    The laccase-catalyzed domino reaction between catechols and 6-substituted 1,2,3,4-tetrahydro-4-oxo-2-thioxo-5-pyrimidinecarbonitriles using aerial O2 as the oxidant delivers new pyrimidobenzothiazole derivatives. The complete structure elucidation of the ring-proton deficient heterocyclic products and the unambiguous determination of the regioselectivity of the reactions have been achieved by extended NMR spectroscopic methods including HSQMBC, super long-range HMBC, and (15)N measurements.

  7. Enrichment of bacteria possessing catechol dioxygenase genes in the rhizosphere of Spirodela polyrrhiza: a mechanism of accelerated biodegradation of phenol.

    PubMed

    Toyama, Tadashi; Sei, Kazunari; Yu, Ning; Kumada, Hirohide; Inoue, Daisuke; Hoang, Hai; Soda, Satoshi; Chang, Young-Cheol; Kikuchi, Shintaro; Fujita, Masanori; Ike, Michihiko

    2009-08-01

    The bacterial community structure in bulk water and in rhizosphere fractions of giant duckweed, Spirodela polyrrhiza, was quantitatively and qualitatively investigated by PCR-based methods using 6 environmental water samples to elucidate the mechanisms underlying selective accumulation of aromatic compound-degrading bacteria in the rhizosphere of S. polyrrhiza. S. polyrrhiza selectively accumulated a diverse range of aromatic compound-degrading bacteria in its rhizosphere, regardless of the origin of water samples, despite no exposure to phenol. The relative abundances of the catechol 1,2-dioxygenase (C12O) gene (C12O DNA) and catechol 2,3-dioxygenase (C23O) gene (C23O DNA) were calculated as the ratios of the copy numbers of these genes to the copy number of 16S rDNA and are referred to as the rhizosphere effect (RE) value. The RE values for C12O DNA and C23O DNA were 1.0 x 10(1)-9.3 x 10(3) and 1.7 x 10(2)-1.5 x 10(4) times as high, respectively, in rhizosphere fractions as in bulk water fractions, and these higher values were associated with a notably higher sequence diversity of C12O DNA and C23O DNA. The RE values during phenol degradation were 3.6 x 10(0)-4.3 x 10(2) and 2.2 x 10(0)-1.7 x 10(2), respectively, indicating the ability of S. polyrrhiza to selectively accumulate aromatic compound-degrading bacteria in its rhizosphere during phenol degradation. The bacterial communities in the rhizosphere fractions differed from those in the bulk water fractions, and those in the bulk water fractions were notably affected by the rhizosphere bacterial communities. S. polyrrhiza released more than 100 types of phenolic compound into its rhizosphere as root exudates at the considerably high specific release rate of 1520mg TOC and 214mg phenolic compounds/d/g root (wet weight). This ability of S. polyrrhiza might result in the selective recruitment and accumulation of a diverse range of bacteria harboring genes encoding C12O and C23O, and the subsequent accelerated

  8. Breast cancer risk associated with genotype polymorphism of the catechol estrogen-metabolizing genes: a multigenic study on cancer susceptibility.

    PubMed

    Cheng, Ting-Chih; Chen, Shou-Tung; Huang, Chiun-Sheng; Fu, Yi-Ping; Yu, Jyh-Cherng; Cheng, Chun-Wen; Wu, Pei-Ei; Shen, Chen-Yang

    2005-01-20

    Estrogen has been suggested to trigger breast cancer development via an initiating mechanism involving its metabolite, catechol estrogen (CE). To examine this hypothesis, we carried out a multigenic case-control study of 469 incident breast cancer patients and 740 healthy controls to define the role of important genes involved in the different metabolic steps that protect against the potentially harmful effects of CE metabolism. We studied the 3 genes involved in CE detoxification by conjugation reactions involving methylation (catechol-O-methyltransferase, COMT), sulfation (sulfotransferase 1A1, SULT1A1), or glucuronidation (UDP-glucuronosyltransferase 1A1, UGT1A1), one (manganese superoxide dismutase, MnSOD) involved in protection against reactive oxidative species-mediated oxidation during the conversion of CE-semiquinone (CE-SQ) to CE-quinone (CE-Q), and 2 of the glutathione S-transferase superfamily, GSTM1 and GSTT1, involved in CE-Q metabolism. Support for this hypothesis came from the observations that (i) there was a trend toward an increased risk of breast cancer in women harboring a greater number of putative high-risk genotypes of these genes (p < 0.05); (ii) this association was stronger and more significant in those women who were more susceptible to estrogen [no history of pregnancy or older (> or =26 years) at first full-term pregnancy (FFTP)]; and (iii) the risks associated with having one or more high-risk genotypes were not the same in women having experienced different menarche-to-FFTP intervals, being more significant in women having been exposed to estrogen for a longer period (> or =12 years) before FFTP. Furthermore, because CE-Q can attack DNA, leading to the formation of double-strand breaks (DSB), we examined whether the relationship between cancer risk and the genotypic polymorphism of CE-metabolizing genes was modified by the genotypes of DSB repair genes, and found that a joint effect of CE-metabolizing genes and one of the two DSB

  9. Naphthalene diols: a new class of antioxidants intramolecular hydrogen bonding in catechols, naphthalene diols, and their aryloxyl radicals.

    PubMed

    Foti, Mario C; Johnson, Erin R; Vinqvist, Melinda R; Wright, James S; Barclay, L Ross C; Ingold, K U

    2002-07-26

    1,8-Naphthalenediol, 5, and its 4-methoxy derivative, 6, were found to be potent H-atom transfer (HAT) compounds on the basis of their rate constants for H-atom transfer to the 2,2-di(4-t-octylphenyl)-1-picrylhydrazyl radical (DOPPH*), k(ArOH/DOPPH)*, or as antioxidants during inhibited styrene autoxidation, k(ArOH/ROO)*, initiated with AIBN. The rate constants showed that 5 and 6 are more active HAT compounds than the ortho-diols, catechol, 1, 2,3-naphthalenediol, 2, and 3,5-di-tert-butylcatechol, 3. Compound 6 has almost twice the antioxidant activity, k(ArOH/ROO)* = 6.0 x 10(6) M(-)(1) s(-1), of that of the vitamin E model compound, 2,2,5,7,8-pentamethyl-6-chromanol, 4. Calculations of the O-H bond dissociation enthalpies compared to those of phenols, (deltaBDEs), of 1-6 predict a HAT order of reactivity of 2 < 1 < 3 approximately 4 < 5 < 6 in general agreement with kinetic results. Calculations on the diols show that intramolecular H-bonding stabilizes the radicals formed on H-atom transfer more than it does the parent diols, and this effect contributes to the increased HAT activity of 5 and 6 compared to the activities of the catechols. For example, the increased stabilization due to the intramolecular H-bond of 5 radical over 5 parent of 8.6 kcal/mol was about double that of 2 radical over 2 parent of 4.6 kcal/mol. Linear free energy plots of log k(ArOH/DOPPH)* and log k(ArOH/ROO)* versus deltaBDEs for compounds 1-6 along with available literature values for nonsterically hindered monophenols placed the compounds on common scales. The derived Evans-Polanyi constants from the plots for the two reactions, alpha(DOPPH)* = 0.48 > alpha(ROO)* = 0.32, gave the expected order, since the ROO* reaction is more exothermic than the DOPPH* reaction. Compound 6 is sufficiently reactive to react directly with oxygen, and it lies off the log k(ArOH/ROO)* versus deltaBDE plot.

  10. The Use of Screen-Printed Electrodes in a Proof of Concept Electrochemical Estimation of Homocysteine and Glutathione in the Presence of Cysteine Using Catechol

    PubMed Central

    Lee, Patricia T.; Lowinsohn, Denise; Compton, Richard G.

    2014-01-01

    Screen printed electrodes were employed in a proof of concept determination of homocysteine and glutathione using electrochemically oxidized catechol via a 1,4-Michael addition reaction in the absence and presence of cysteine, and each other. Using cyclic voltammetry, the Michael reaction introduces a new adduct peak which is analytically useful in detecting thiols. The proposed procedure relies on the different rates of reaction of glutathione and homocysteine with oxidized catechol so that at fast voltage scan rates only homocysteine is detected in cyclic voltammetry. At slower scan rates, both glutathione and homocysteine are detected. The combination of the two sets of data provides quantification for homocysteine and glutathione. The presence of cysteine is shown not to interfere provided sufficient high concentrations of catechol are used. Calibration curves were determined for each homocysteine and glutathione detection; where the sensitivities are 0.019 μA·μM−1 and 0.0019 μA·μM−1 and limit of detections are ca. 1.2 μM and 0.11 μM for homocysteine and glutathione, respectively, within the linear range. This work presents results with potential and beneficial use in re-useable and/or disposable point-of-use sensors for biological and medical applications. PMID:24926695

  11. The effect of substituents on the surface modification of anatase nanoparticles with catecholate-type ligands: a combined DFT and experimental study.

    PubMed

    Savić, Tatjana D; Čomor, Mirjana I; Nedeljković, Jovan M; Veljković, Dušan Ž; Zarić, Snežana D; Rakić, Vesna M; Janković, Ivana A

    2014-10-14

    The surface modification of nanocrystalline TiO2 particles (45 Å) with catecholate-type ligands having different electron donating/electron withdrawing substituent groups, specifically 3-methylcatechol, 4-methylcatechol, 3-methoxycatechol, 3,4-dihydroxybenzaldehyde and 4-nitrocatechol, was found to alter the optical properties of nanoparticles in a similar way to catechol. The formation of the inner-sphere charge-transfer (CT) complexes results in a red shift of the semiconductor absorption compared to unmodified nanocrystallites and a reduction of the effective band gap, being slightly less pronounced in the case of electron withdrawing substituents. The investigated ligands have the optimal geometry for binding to surface Ti atoms, resulting in ring coordination complexes of the catecholate type (binuclear bidentate binding-bridging) thus restoring six-coordinated octahedral geometry of surface Ti atoms. From the absorption measurements (Benesi-Hildebrand plot), the stability constants in methanol/water = 90/10 solutions at pH 2 in the order of 10(3) M(-1) have been determined. The binding structures were investigated by using FTIR spectroscopy. Thermal stability of CT-complexes was investigated by using TG/DSC/MS analysis. Quantum chemical calculations on model systems using density functional theory (DFT) were performed to obtain the vibrational frequencies of charge transfer complexes, and the calculated values were compared with the experimental data.

  12. Substrate-dependent aromatic ring fission of catechol and 2-aminophenol with O2 catalyzed by a nonheme iron complex of a tripodal N4 ligand.

    PubMed

    Lakshman, Triloke Ranjan; Chatterjee, Sayanti; Chakraborty, Biswarup; Paine, Tapan Kanti

    2016-06-01

    The catalytic reactivity of an iron(ii) complex [(TPA)Fe(II)(CH3CN)2](2+) (1) (TPA = tris(2-pyridylmethyl)amine) towards oxygenative aromatic C-C bond cleavage of catechol and 2-aminophenol is presented. Complex 1 exhibits catalytic and regioselective C-C bond cleavage of 3,5-di-tert-butylcatechol (H2DBC) to form intradiol products, whereas it catalyzes extradiol-type C-C bond cleavage of 2-amino-4,6-di-tert-butylphenol (H2AP). The catalytic reactions are found to be pH-dependent and the complex exhibits maximum turnovers at pH 5 in acetonitrile-phthalate buffer. An iron(iii)-catecholate complex [(TPA)Fe(III)(DBC)](+) (2) is formed in the ring cleavage of catechol. In the extradiol-type cleavage of H2AP, an iron(iii)-2-iminobenzosemiquinonate complex [(TPA)Fe(III)(ISQ)](2+) (3) (ISQ = 4,6-di-tert-butyl-2-iminobenzosemiquinonate radical anion) is observed in the reaction pathway. This work shows the importance of the nature of 'redox non-innocent' substrates in governing the mode of ring fission reactivity.

  13. Formation of Light Absorbing Soluble Secondary Organics and Insoluble Polymeric Particles from the Dark Reaction of Catechol and Guaiacol with Fe(III).

    PubMed

    Slikboer, Samantha; Grandy, Lindsay; Blair, Sandra L; Nizkorodov, Sergey A; Smith, Richard W; Al-Abadleh, Hind A

    2015-07-01

    Transition metals such as iron are reactive components of environmentally relevant surfaces. Here, dark reaction of Fe(III) with catechol and guaiacol was investigated in an aqueous solution at pH 3 under experimental conditions that mimic reactions in the adsorbed phase of water. Using UV-vis spectroscopy, liquid chromatography, mass spectrometry, elemental analysis, dynamic light scattering, and electron microscopy techniques, we characterized the reactants, intermediates, and products as a function of reaction time. The reactions of Fe(III) with catechol and guaiacol produced significant changes in the optical spectra of the solutions due to the formation of light absorbing secondary organics and colloidal organic particles. The primary steps in the reaction mechanism were shown to include oxidation of catechol and guaiacol to hydroxy- and methoxy-quinones. The particles formed within a few minutes of reaction and grew to micron-size aggregates after half an hour reaction. The mass-normalized absorption coefficients of the particles were comparable to those of strongly absorbing brown carbon compounds produced by biomass burning. These results could account for new pathways that lead to atmospheric secondary organic aerosol formation and abiotic polymer formation on environmental surfaces mediated by transition metals.

  14. Potentiometric and NMR complexation studies of phenylboronic acid PBA and its aminophosphonate analog with selected catecholamines

    NASA Astrophysics Data System (ADS)

    Ptak, Tomasz; Młynarz, Piotr; Dobosz, Agnieszka; Rydzewska, Agata; Prokopowicz, Monika

    2013-05-01

    Boronic acids are a class of intensively explored compounds, which according to their specific properties have been intensively explored in last decades. Among them phenylboronic acids and their derivatives are most frequently examined as receptors for diverse carbohydrates. In turn, there is a large gap in basic research concerning complexation of catecholamines by these compounds. Therefore, we decided to undertake studies on interaction of chosen catecholamines, namely: noradrenaline (norephinephrine), dopamine, L-DOPA, DOPA-P (phosphonic analog of L-DOPA) and catechol, with simple phenyl boronic acid PBA by means of potentiometry and NMR spectroscopy. For comparison, the binding properties of recently synthesized phenylboronic receptor 1 bearing aminophosphonate function in meta-position were investigated and showed promising ability to bind catecholamines. The protonation and stability constants of PBA and receptor 1 complexes were examined by potentiometry. The obtained results demonstrated that PBA binds the catecholamines with the following affinity order: noradrenaline ⩾ dopamine ≈ L-DOPA > catechol > DOPA-P, while its modified analog 1 reveals slightly different preferences: dopamine > noradrenaline > catechol > L-DOPA > DOPA-P.

  15. Perceived stress during pregnancy and the catechol-O-methyltransferase (COMT) rs165599 polymorphism impacts on childhood IQ.

    PubMed

    Lamb, Yvette N; Thompson, John M D; Murphy, Rinki; Wall, Clare; Kirk, Ian J; Morgan, Angharad R; Ferguson, Lynnette R; Mitchell, Edwin A; Waldie, Karen E

    2014-09-01

    Maternal stress during pregnancy has been associated with a range of adverse outcomes in offspring and the catechol-O-methyltransferase (COMT) gene has been linked to differential susceptibility to the consequences of antenatal stress. This study examined two functional polymorphisms of the COMT gene (rs4680 and rs165599) in relation to maternal perceived stress and childhood cognitive performance. Data from the longitudinal Auckland Birthweight Collaborative (ABC) study was used. Maternal perceived stress over the prior month was measured at birth, 3.5 and 7years. Full-Scale IQ (FSIQ) was measured at ages 7 and 11. At age 11, a total of 546 DNA samples were collected from the child participants. Data were subjected to a series of split-plot ANCOVAs with birthweight for gestational age and maternal school leaving age as covariates. There were direct effects of maternal stress during the last month of pregnancy on offspring FSIQ at ages 7 and 11years. A significant interaction revealed that children exposed to high maternal antenatal stress had significantly lower FSIQ scores at both 7 and 11years of age than those exposed to low stress, only when they were carriers of the rs165599 G allele. At each age, this difference was of approximately 5 IQ points. The G allele of the rs165599 polymorphism may confer genetic susceptibility to negative cognitive outcomes arising from exposure to antenatal stress. This finding highlights the need to consider gene-environment interactions when investigating the outcomes of antenatal stress exposure. PMID:24955500

  16. Association between the catechol-o-methyltransferase val158met polymorphism with susceptibility and severity of carpal tunnel syndrome

    PubMed Central

    Eroğlu, P; Görükmez, O; Özemri Sağ, Ş; Yakut, T

    2015-01-01

    Abstract Carpal tunnel syndrome (CTS) is the most common entrapment neuropathy of the upper extremity. In this study, we aimed to clarify the relationships between the catechol-O-methyltransferase (COMT) gene Val158Met (rs4680) polymorphism and development, functional and clinical status of CTS. Ninety-five women with electro diagnostically confirmed CTS and 95 healthy controls were enrolled in the study. The functional and clinical status of the patients was measured by the Turkish version of the Boston Questionnaire and intensity of pain related to the past 2 weeks was evaluated on a visual analog scale (VAS). The Val158Met polymorphism was determined using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), method. We divided patients according to the genotypes of the Val158Met polymorphism as Val/Val, Val/Met and Met/Met. There were not any significant differences in terms of Val158Met polymorphisms between patients and healthy controls (p >0.05). We also did not find any relationships between the Val158Met polymorphism and CTS (p >0.05). In conclusion, although we did not find any relationships between CTS and the Val158Met polymorphism, we could not generalize this result to the general population. Future studies are warranted to conclude precise associations.

  17. Catechol-O-methyltransferase Val158Met genotype moderates the effect of disorganized attachment on social development in young children.

    PubMed

    Hygen, Beate Wold; Guzey, Ismail Cuneyt; Belsky, Jay; Berg-Nielsen, Turid Suzanne; Wichstrøm, Lars

    2014-11-01

    Children with histories of disorganized attachment exhibit diverse problems, possibly because disorganization takes at least two distinctive forms as children age: controlling-punitive and controlling-caregiving. This variation in the developmental legacy of disorganization has been attributed primarily to variations in children's rearing experiences. Here an alternative explanation of these divergent sequelae of disorganization is evaluated: one focused on genotype. Structural equation modeling was applied to data on 704 Norwegian children to test whether the catechol-O-methyltransferase Val158Met genotype moderates the effect of disorganized attachment, which was measured dimensionally at 4 years of age using the Manchester Child Attachment Story Task, on changes in aggressive behavior and social competence from ages 4 to 6. Children who scored high on disorganization and were homozygous for the valine allele displayed significantly greater increases in aggression and decreases in self-oriented social skills (e.g., self-regulation and assertiveness) over time than did their disorganized counterparts carrying the methionine allele, whereas disorganized children carrying the methionine allele increased their other-oriented social skill (e.g., cooperation and responsibility) scores more than did valine-homozygous children. These results are consistent with the controlling-punitive and controlling-caregiving behaviors observed in disorganized children, suggesting that the children's genotype contributed to variations in the social development of disorganized children. PMID:24914507

  18. Resolving Non-Specific and Specific Adhesive Interactions of Catechols at Solid/Liquid Interfaces at the Molecular Scale.

    PubMed

    Utzig, Thomas; Stock, Philipp; Valtiner, Markus

    2016-08-01

    The adhesive system of mussels evolved into a powerful and adaptive system with affinity to a wide range of surfaces. It is widely known that thereby 3,4-dihydroxyphenylalanine (Dopa) plays a central role. However underlying binding energies remain unknown at the single molecular scale. Here, we use single-molecule force spectroscopy to estimate binding energies of single catechols with a large range of opposing chemical functionalities. Our data demonstrate significant interactions of Dopa with all functionalities, yet most interactions fall within the medium-strong range of 10-20 kB T. Only bidentate binding to TiO2 surfaces exhibits a higher binding energy of 29 kB T. Our data also demonstrate at the single-molecule level that oxidized Dopa and amines exhibit interaction energies in the range of covalent bonds, confirming the important role of Dopa for cross-linking in the bulk mussel adhesive. We anticipate that our approach and data will further advance the understanding of biologic and technologic adhesives. PMID:27374053

  19. The effect of GSM and TETRA mobile handset signals on blood pressure, catechol levels and heart rate variability.

    PubMed

    Barker, Anthony T; Jackson, Peter R; Parry, Helen; Coulton, Leslie A; Cook, Greg G; Wood, Steven M

    2007-09-01

    An acute rise in blood pressure has been reported in normal volunteers during exposure to signals from a mobile phone handset. To investigate this finding further we carried out a double blind study in 120 healthy volunteers (43 men, 77 women) in whom we measured mean arterial pressure (MAP) during each of six exposure sessions. At each session subjects were exposed to one of six different radio frequency signals simulating both GSM and TETRA handsets in different transmission modes. Blood catechols before and after exposure, heart rate variability during exposure, and post exposure 24 h ambulatory blood pressure were also studied. Despite having the power to detect changes in MAP of less than 1 mmHg none of our measurements showed any effect which we could attribute to radio frequency exposure. We found a single statistically significant decrease of 0.7 mmHg (95% CI 0.3-1.2 mmHg, P = .04) with exposure to GSM handsets in sham mode. This may be due to a slight increase in operating temperature of the handsets when in this mode. Hence our results have not confirmed the original findings of an acute rise in blood pressure due to exposure to mobile phone handset signals. In light of this negative finding from a large study, coupled with two smaller GSM studies which have also proved negative, we are of the view that further studies of acute changes in blood pressure due to GSM and TETRA handsets are not required. PMID:17486598

  20. No association between germline variation in catechol-O-methyltransferase and colorectal cancer survival in postmenopausal women

    PubMed Central

    Passarelli, Michael N.; Newcomb, Polly A.; Makar, Karen W.; Burnett-Hartman, Andrea N.; Phipps, Amanda I.; David, Sean P.; Hsu, Li; Harrison, Tabitha A.; Hutter, Carolyn M.; Duggan, David J.; White, Emily; Chan, Andrew T.; Peters, Ulrike

    2013-01-01

    Objective Sex-steroid hormones play a role in colorectal cancer (CRC) development, but little is known about their influence on tumor progression and metastasis. Because catechol-O-methyltransferase activity (COMT; 22q11.21) is an important component of estrogen-mediated carcinogenesis, we hypothesized that germline variation in COMT may be associated with CRC survival. Methods We identified 10 single-nucleotide polymorphisms (SNPs) that tagged variation across both isoforms of COMT in 2,458 women with CRC from the Nurses’ Health Study (NHS), Postmenopausal Hormones Supplementary Study to the Colon Cancer Family Registry (PMH-CCFR), VITamins And Lifestyle (VITAL) Study, and Women’s Health Initiative (WHI). All four studies participate in the Genetics and Epidemiology of Colorectal Cancer Consortium (GECCO). Results Over a median follow-up of 7 years across all studies, there were 799 deaths, including 566 from CRC. Accounting for multiple comparisons, no associations between the SNPs and CRC-specific or overall survival reached statistical significance, including the well-characterized Val108/158Met polymorphism (rs4680; hazard ratio per minor allele [HR], 1.04; 95% confidence interval [CI], 0.92–1.17 for CRC-specific survival and 1.01; 0.90–1.14 for overall survival). Conclusions In this large study of women with CRC, we found no evidence that common inherited variation in COMT is associated with survival-time after diagnosis. PMID:23880798

  1. Catechol-O-Methyltransferase Gene Polymorphism Modifies the Effect of Coffee Intake on Incidence of Acute Coronary Events

    PubMed Central

    Happonen, Pertti; Voutilainen, Sari; Tuomainen, Tomi-Pekka; Salonen, Jukka T.

    2006-01-01

    Background The role of coffee intake as a risk factor for coronary heart disease (CHD) has been debated for decades. We examined whether the relationship between coffee intake and incidence of CHD events is dependent on the metabolism of circulating catecholamines, as determined by functional polymorphism of the catechol-O-methyltransferase (COMT) gene. Methodology/Principal Findings In a cohort of 773 men who were 42 to 60 years old and free of symptomatic CHD at baseline in 1984–89, 78 participants experienced an acute coronary event during an average follow-up of 13 years. In logistic regression adjusting for age, smoking, family history of CHD, vitamin C deficiency, blood pressure, plasma cholesterol concentration, and diabetes, the odds ratio (90% confidence interval) comparing heavy coffee drinkers with the low activity COMT genotype with those with the high activity or heterozygotic genotypes was 3.2 (1.2–8.4). Urinary adrenaline excretion increased with increasing coffee intake, being over two-fold in heavy drinkers compared with nondrinkers (p = 0.008 for trend). Conclusions/Significance Heavy coffee consumption increases the incidence of acute coronary events in men with low but not high COMT activity. Further studies are required to determine to which extent circulating catecholamines mediate the relationship between coffee intake and CHD. PMID:17205121

  2. Implicit versus explicit solvent in free energy calculations of enzyme catalysis: Methyl transfer catalyzed by catechol O-methyltransferase

    NASA Astrophysics Data System (ADS)

    Rod, Thomas H.; Rydberg, Patrik; Ryde, Ulf

    2006-05-01

    We compare free energy calculations for the methyl transfer reaction catalyzed by catechol O-methyltransferase using the quantum mechanical/molecular mechanical free energy method with implicit and explicit solvents. An analogous methylation reaction in a solution is also studied. For the explicit solvent model, we use the three-point transferable intermolecular potential model, and for the implicit model, we use the generalized Born molecular volume model as implemented in CHARMM. We find that activation and reaction free energies calculated with the two models are very similar, despite some structural differences that exist. A significant change in the polarization of the environment occurs as the reaction proceeds. This is more pronounced for the reaction in a solution than for the enzymatic reaction. For the enzymatic reaction, most of the changes take place in the protein rather than in the solvent, and, hence, the benefit of having an instantaneous relaxation of the solvent degrees of freedom is less pronounced for the enzymatic reaction than for the reaction in a solution. This is a likely reason why energies of the enzyme reaction are less sensitive to the choice of atomic radii than are energies of the reaction in a solution.

  3. Impedance spectroscopy study of a catechol-modified activated carbon electrode as active material in electrochemical capacitor

    NASA Astrophysics Data System (ADS)

    Cougnon, C.; Lebègue, E.; Pognon, G.

    2015-01-01

    Modified activated carbon (Norit S-50) electrodes with electrochemical double layer (EDL) capacitance and redox capacitance contributions to the electric charge storage were tested in 1 M H2SO4 to quantify the benefit and the limitation of the surface redox reactions on the electrochemical performances of the resulting pseudo-capacitive materials. The electrochemical performances of an electrochemically anodized carbon electrode and a catechol-modified carbon electrode, which make use both EDL capacitance of the porous structure of the carbon and redox capacitance, were compared to the performances obtained for the pristine carbon. Nitrogen gas adsorption measurements have been used for studying the impact of the grafting on the BET surface area, pore size distribution, pore volume and average pore diameter. The electrochemical behavior of carbon materials was studied by cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The EIS data were discussed by using a complex capacitance model that allows defining the characteristic time constant, the global capacitance and the frequency at which the maximum charge stored is reached. The EIS measurements were achieved at different dc potential values where a redox activity occurs and the evolution of the capacitance and the capacitive relaxation time with the electrode potential are presented. Realistic galvanostatic charge/discharge measurements performed at different current rates corroborate the results obtained by impedance.

  4. Identification of CtpL as a Chromosomally Encoded Chemoreceptor for 4-Chloroaniline and Catechol in Pseudomonas aeruginosa PAO1

    PubMed Central

    Takeuchi, Kazuki; Oku, Shota; Kataoka, Naoya; Nitisakulkan, Tisana; Tajima, Takahisa; Kato, Junichi

    2013-01-01

    Bacterial chemotaxis influences the ability of bacteria to survive and thrive in most environments, including polluted ones. Despite numerous reports of the phenotypic characterization of chemotactic bacteria, only a few molecular details of chemoreceptors for aromatic pollutants have been described. In this study, the molecular basis of chemotaxis toward an environmentally toxic chlorinated aromatic pollutant, 4-chloroaniline (4CA), was evaluated. Among the three Pseudomonas spp. tested, Pseudomonas aeruginosa PAO1 exhibited positive chemotaxis both to the nonmetabolizable 4CA, where 4-chloroacetanilide was formed as a dead-end transformation product, and to the metabolizable catechol. Molecular analysis of all 26 mutants with a disrupted methyl-accepting chemotaxis gene revealed that CtpL, a chromosomally encoded chemoreceptor, was responsible for the positive chemotactic response toward 4CA. Since CtpL has previously been described to be a major chemoreceptor for inorganic phosphate at low concentrations in PAO1, this report describes a fortuitous ability of CtpL to function toward aromatic pollutants. In addition, its regulation not only was dependent on the presence of the chemoattractant inducer but also was regulated by conditions of phosphate starvation. These results expand the range of known chemotactic transducers and their function in the environmental bacterium PAO1. PMID:24038698

  5. Simultaneous determination of hydroquinone, catechol and resorcinol by voltammetry using graphene screen-printed electrodes and partial least squares calibration.

    PubMed

    Aragó, Miriam; Ariño, Cristina; Dago, Àngela; Díaz-Cruz, José Manuel; Esteban, Miquel

    2016-11-01

    Catechol (CC), resorcinol (RC) and hydroquinone (HQ) are dihydroxybenzene isomers that usually coexist in different samples and can be determined using voltammetric techniques taking profit of their fast response, high sensitivity and selectivity, cheap instrumentation, simple and timesaving operation modes. However, a strong overlapping of CC and HQ signals is observed hindering their accurate analysis. In the present work, the combination of differential pulse voltammetry with graphene screen-printed electrodes (allowing detection limits of 2.7, 1.7 and 2.4µmolL(-1) for HQ, CC and RC respectively) and the data analysis by partial least squares calibration (giving root mean square errors of prediction, RMSEP values, of 2.6, 4.1 and 2.3 for HQ, CC and RC respectively) has been proposed as a powerful tool for the quantification of mixtures of these dihydroxybenzene isomers. The commercial availability of the screen-printed devices and the low cost and simplicity of the analysis suggest that the proposed method can be a valuable alternative to chromatographic and electrophoretic methods for the considered species. The method has been applied to the analysis of these isomers in spiked tap water.

  6. BODIPY-Appended 2-(2-Pyridyl)benzimidazole Platinum(II) Catecholates for Mitochondria-Targeted Photocytotoxicity.

    PubMed

    Mitra, Koushambi; Gautam, Srishti; Kondaiah, Paturu; Chakravarty, Akhil R

    2016-09-01

    Platinum(II) complexes of the type [Pt(L)(cat)] (1 and 2), in which H2 cat is catechol and L represents two 2-(2-pyridyl)benzimidazole ligands with 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) pendants, were synthesized to achieve mitochondria-targeted photocytotoxicity. The complexes showed strong absorptions in the range λ=510-540 nm. Complex 1 exhibited intense emission at λ=525 nm in 1 % DMSO/water solution (fluorescence quantum yield of 0.06). Nanosecond transient absorption spectral features indicated an enhanced population of the triplet excited state in di-iodinated complex 2. The generation of singlet oxygen by complex 2 upon exposure to visible light, as evidenced from experiments with 1,3-diphenylisobenzofuran, is suitable for photodynamic therapy because of the remarkable photosensitizing ability. The complexes resulted in excellent photocytotoxicity in HaCaT cells (half maximal inhibitory concentration IC50 ≈3 μm, λ=400-700 nm, light dose=10 J cm(-2) ), but they remained non-toxic in the dark (IC50 >100 μm). Confocal microscopy images of 1 and Pt estimation from isolated mitochondria showed colocalization of the complexes in the mitochondria. Complex 2 displayed generation of reactive oxygen species induced by visible light, disruption of the mitochondrial membrane potential, and apoptosis. PMID:27465792

  7. The impact of Val108/158Met polymorphism of catechol-O-methyltransferase on brain oscillations during working memory.

    PubMed

    Altamura, Mario; Elvevåg, Brita; Goldberg, Terry E; Carver, Frederick W; Weinberger, Daniel R; Coppola, Richard

    2016-01-01

    This study investigated whether catechol-O-methyltransferase (COMT) Val/Met polymorphism was associated with variation in event-related desynchronization/synchronization (ERD/ERS) of responses during working memory (WM). 11 Val/Val and 11 Met/Met homozygous participants underwent magnetoencephalography (MEG) while performing a WM task. In contrast to small effects behaviourally, during the delay period Val/Val individuals showed lower ERS in the gamma band (Hz 30-50) in frontal regions, increased ERS in the alpha band (Hz 8-12) in the right frontal and parietal regions and increased ERD in the beta band (Hz 14-30) in the left fronto-temporal regions as compared with Met/Met homozygous individuals. During the response period Val/Val participants showed greater beta ERD in the prefrontal and parietotemporal regions. These results demonstrate that COMT genotype has a strong impact on brain responses (oscillatory activity) during WM performance likely a consequence of compensatory activity during the delay and response periods. PMID:26536074

  8. Erythrocyte catechol-O-methyltransferase activity: genetic analysis in nuclear families with one child affected by Down syndrome.

    PubMed

    Brahe, C; Serra, A; Morton, N E

    1985-06-01

    Erythrocyte catechol-O-methyltransferase (COMT) activity was measured in 142 members of 32 nuclear families in which one child had Down syndrome (DS). The mean activity in subjects with trisomy 21 appears higher than in parents and sibs, though not significantly so. However, this fact does not seem to modify the properties expected for a trait genetically controlled in a diploid population. The commingling analysis of the COMT activity in the whole group, and in each subgroup of relatives, suggests a mixture of two or, more likely, three components, the latter being in agreement with a transmission model of genes without dominance. The most parsimonious hypothesis supported by the mixed model segregation analysis is that of an additive major locus (d = 0.5) with an estimated frequency of 0.40 +/- 0.03 for the COMTH gene, to which a small polygenic effect (H = 0.067) can be added. This hypothesis is supported further by the analysis of family resemblance, r = 0.45 +/- 0.12 being the maximum likelihood estimator of the intraclass correlation among sibs. The higher COMT activity in DS subjects may reflect a situation of general enzyme disorder only indirectly connected with trisomy of chromosome 21. PMID:3160238

  9. Complex multilocus effects of catechol-O-methyltransferase haplotypes predict pain and pain interference 6 weeks after motor vehicle collision

    PubMed Central

    Bortsov, Andrey V.; Diatchenko, Luda; McLean, Samuel A.

    2013-01-01

    Catechol-O-methyltransferase, encoded by COMT gene, is the primary enzyme that metabolizes catecholamines. COMT haplotypes have been associated with vulnerability to persistent non-traumatic pain. In this prospective observational study, we investigated the influence of COMT on persistent pain and pain interference with life functions after motor vehicle collision (MVC) in 859 European American adults for whom overall pain (0–10 numeric rating scale) and pain interference (Brief Pain Inventory) were assessed at week 6 after MVC. Ten single nucleotide polymorphisms (SNPs) spanning the COMT gene were successfully genotyped, nine were present in three haploblocks: block 1 (rs2020917, rs737865, rs1544325), block 2 (rs4633, rs4818, rs4680, rs165774) and block 3 (rs174697, rs165599). After adjustment for multiple comparisons, haplotype TCG from block 1 predicted decreased pain interference (p =.004). The pain-protective effect of the low pain sensitivity (LPS, CGGG) haplotype from block 2 was only observed if at least one TCG haplotype was present in block 1 (haplotype × haplotype interaction p=.002 and <.0001 for pain and pain interference, respectively). Haplotype AG from block 3 was associated with pain and interference in males only (sex × haplotype interaction p=.005 and .0005, respectively). These results suggest that genetic variants in the distal promoter are important contributors to the development of persistent pain after MVC, directly and via the interaction with haplotypes in the coding region of the gene. PMID:23963787

  10. Simultaneous determination of hydroquinone, catechol and resorcinol by voltammetry using graphene screen-printed electrodes and partial least squares calibration.

    PubMed

    Aragó, Miriam; Ariño, Cristina; Dago, Àngela; Díaz-Cruz, José Manuel; Esteban, Miquel

    2016-11-01

    Catechol (CC), resorcinol (RC) and hydroquinone (HQ) are dihydroxybenzene isomers that usually coexist in different samples and can be determined using voltammetric techniques taking profit of their fast response, high sensitivity and selectivity, cheap instrumentation, simple and timesaving operation modes. However, a strong overlapping of CC and HQ signals is observed hindering their accurate analysis. In the present work, the combination of differential pulse voltammetry with graphene screen-printed electrodes (allowing detection limits of 2.7, 1.7 and 2.4µmolL(-1) for HQ, CC and RC respectively) and the data analysis by partial least squares calibration (giving root mean square errors of prediction, RMSEP values, of 2.6, 4.1 and 2.3 for HQ, CC and RC respectively) has been proposed as a powerful tool for the quantification of mixtures of these dihydroxybenzene isomers. The commercial availability of the screen-printed devices and the low cost and simplicity of the analysis suggest that the proposed method can be a valuable alternative to chromatographic and electrophoretic methods for the considered species. The method has been applied to the analysis of these isomers in spiked tap water. PMID:27591597

  11. Catechol-O-methyl Transferase and Expression of Schizophrenia in 73 Adults with 22q11 Deletion Syndrome

    PubMed Central

    Bassett, Anne S.; Caluseriu, Oana; Weksberg, Rosanna; Young, Donald A.; Chow, Eva W.C.

    2011-01-01

    Background Catechol-O-methyl transferase (COMT) is a candidate gene for schizophrenia with a role in dopamine metabolism, particularly in frontal cortex. COMT is within the region commonly deleted in 22q11 deletion syndrome (22q11DS), a syndrome with high prevalence of schizophrenia. We examined the role of COMT in schizophrenia-related expression in 22q11DS. Methods We genotyped the COMT functional Val158/108Met allele in 73 Caucasian adults with 22q11DS (36 men, 37 women; aged 33.8, SD 10.1 years; 37 Met, 36 Val hemizygosity) blind to clinical data and assessed effects on symptoms and frontal functioning. Results The lower activity Met allele was not significantly more prevalent than the Val allele in 33 subjects with schizophrenia. Excitement symptoms were more severe, however, and three frontal cognitive tests (theory of mind, Trails B, and olfactory identification), communication, and social functioning measures showed significantly worse performance with Met allele hemizygosity, even after accounting for effects of schizophrenia. Conclusions The results suggest that hemizygosity of the COMT functional allele exerts an effect on some measures of frontal functioning in 22q11DS. Elevated levels of tonic dopamine activation associated with the COMT Met allele may underlie these aspects of expression. We must look elsewhere for causes of the high prevalence of schizophrenia in 22q11DS, however. PMID:17217925

  12. The abiotic degradation of soil organic matter to oxalic acid

    NASA Astrophysics Data System (ADS)

    Studenroth, Sabine; Huber, Stefan; Schöler, H. F.

    2010-05-01

    The abiotic degradation of soil organic matter to volatile organic compounds was studied intensely over the last years (Keppler et al., 2000; Huber et al., 2009). It was shown that soil organic matter is oxidised due to the presence of iron (III), hydrogen peroxide and chloride and thereby produces diverse alkyl halides, which are emitted into the atmosphere. The formation of polar halogenated compounds like chlorinated acetic acids which are relevant toxic environmental substances was also found in soils and sediments (Kilian et al., 2002). The investigation of the formation of other polar halogenated and non-halogenated compounds like diverse mono- and dicarboxylic acids is going to attain more and more importance. Due to its high acidity oxalic acid might have impacts on the environment e.g., nutrient leaching, plant diseases and negative influence on microbial growth. In this study, the abiotic formation of oxalic acid in soil is examined. For a better understanding of natural degradation processes mechanistic studies were conducted using the model compound catechol as representative for structural elements of the humic substances and its reaction with iron (III) and hydrogen peroxide. Iron is one of the most abundant elements on earth and hydrogen peroxide is produced by bacteria or through incomplete reduction of oxygen. To find suitable parameters for an optimal reaction and a qualitative and quantitative analysis method the following reaction parameters are varied: concentration of iron (III) and hydrogen peroxide, time dependence, pH-value and influence of chloride. Analysis of oxalic acid was performed employing an ion chromatograph equipped with a conductivity detector. The time dependent reaction shows a relatively fast formation of oxalic acid, the optimum yield is achieved after 60 minutes. Compared to the concentration of catechol an excess of hydrogen peroxide as well as a low concentration of iron (III) are required. In absence of chloride the

  13. A Novel Muconic Acid Biosynthesis Approach by Shunting Tryptophan Biosynthesis via Anthranilate

    PubMed Central

    Sun, Xinxiao; Lin, Yuheng; Huang, Qin; Yuan, Qipeng

    2013-01-01

    Muconic acid is the synthetic precursor of adipic acid, and the latter is an important platform chemical that can be used for the production of nylon-6,6 and polyurethane. Currently, the production of adipic acid relies mainly on chemical processes utilizing petrochemicals, such as benzene, which are generally considered environmentally unfriendly and nonrenewable, as starting materials. Microbial synthesis from renewable carbon sources provides a promising alternative under the circumstance of petroleum depletion and environment deterioration. Here we devised a novel artificial pathway in Escherichia coli for the biosynthesis of muconic acid, in which anthranilate, the first intermediate in the tryptophan biosynthetic branch, was converted to catechol and muconic acid by anthranilate 1,2-dioxygenase (ADO) and catechol 1,2-dioxygenase (CDO), sequentially and respectively. First, screening for efficient ADO and CDO from different microbial species enabled the production of gram-per-liter level muconic acid from supplemented anthranilate in 5 h. To further achieve the biosynthesis of muconic acid from simple carbon sources, anthranilate overproducers were constructed by overexpressing the key enzymes in the shikimate pathway and blocking tryptophan biosynthesis. In addition, we found that introduction of a strengthened glutamine regeneration system by overexpressing glutamine synthase significantly improved anthranilate production. Finally, the engineered E. coli strain carrying the full pathway produced 389.96 ± 12.46 mg/liter muconic acid from simple carbon sources in shake flask experiments, a result which demonstrates scale-up potential for microbial production of muconic acid. PMID:23603682

  14. Simultaneous electroanalytical determination of hydroquinone and catechol in the presence of resorcinol at an SiO2/C electrode spin-coated with a thin film of Nb2O5.

    PubMed

    Canevari, Thiago C; Arenas, Leliz T; Landers, Richard; Custodio, Rogério; Gushikem, Yoshitaka

    2013-01-01

    This paper describes the development, characterization and application of an Nb(2)O(5) film formed on the surface of a carbon ceramic material, SiO(2)/C, obtained by a sol-gel method, using the spin-coating technique. The working electrode using this material will be designated as SiCNb. Hydroquinone and catechol can be oxidized at this electrode in the presence of resorcinol, allowing their simultaneous detection. The electrochemical properties of the resulting electrode were investigated using cyclic and differential pulse voltammetry techniques. Well-defined and separated oxidation peaks were observed by differential pulse voltammetry in Tris-HCl buffer solution at pH 7 containing 1 mol L(-1) KCl in the supporting electrolyte solution. The SiCNb electrode exhibited high sensitivity in the simultaneous determination of hydroquinone and catechol in the presence of resorcinol, with the limits of detection for hydroquinone and catechol being 1.6 μmol L(-1) and 0.8 μmol L(-1), respectively. Theoretical calculations were performed to determine the ionization energies of hydroquinone, catechol and resorcinol; the results were used to explain the simultaneous determination of species by differential pulse voltammetry. The presence of resorcinol did not produce any interference in the simultaneous detection of hydroquinone and catechol on the surface of the modified electrode.

  15. Mussel-inspired soft-tissue adhesive based on poly(diol citrate) with catechol functionality.

    PubMed

    Ji, Yali; Ji, Ting; Liang, Kai; Zhu, Lei

    2016-02-01

    Marine mussels tightly adhering to various underwater surfaces inspires human to design adhesives for wet tissue adhesion in surgeries. Characterization of mussel adhesive plaques describes a matrix of proteins containing 3,4-dihydroxyphenylalanine (DOPA), which provides strong adhesion in aquatic conditions. Several synthetic polymer systems have been developed based on this DOPA chemistry. Herein, a citrate-based tissue adhesives (POEC-d) was prepared by a facile one-pot melt polycondensation of two diols including 1,8-octanediol and poly(ethylene oxide) (PEO), citric acid (CA) and dopamine, and the effects of hydrophilic and soft PEO on the properties of adhesives were studied. It was found that the obtained adhesives exhibited water-soluble when the mole ratio of PEO to 1,8-octanediol was 70%, and the equilibrium swelling percentage of cured adhesive was about 144%, and degradation rate was in the range of 1-2 weeks. The cured adhesives demonstrated soft rubber-like behavior. The lap shear adhesion strength measured by bonding wet pig skin was in the range of 21.7-33.7 kPa, which was higher than that of commercial fibrin glue (9-15 kPa). The cytotoxicity tests showed the POEC-d adhesives had a low cytotoxicity. Our results supports that POEC-d adhesives, which combined strong wet adhesion with good biodegradability, acceptable swelling ratio, good elasticity and low cytotoxicity, have potentials in surgeries where surgical tissue adhesives, sealants, and hemostatic agents are used. PMID:26704547

  16. Oxidative modification of human ceruloplasmin induced by a catechol neurotoxin, salsolinol

    PubMed Central

    Kim, Seung-Sub; Kang, Jae Yoon; Kang, Jung Hoon

    2016-01-01

    Salsolinol (SAL), a compound derived from dopamine metabolism, is the most probable neurotoxin involved in the pathogenesis of Parkinson’s disease (PD). In this study, we investigated the modification and inactivation of human ceruloplasmin (hCP) induced by SAL. Incubation of hCP with SAL increased the protein aggregation and enzyme inactivation in a dose-dependent manner. Reactive oxygen species scavengers and copper chelators inhibited the SAL-mediated hCP modification and inactivation. The formation of dityrosine was detected in SAL-mediated hCP aggregates. Amino acid analysis post the exposure of hCP to SAL revealed that aspartate, histidine, lysine, threonine and tyrosine residues were particularly sensitive. Since hCP is a major copper transport protein, oxidative damage of hCP by SAL may induce perturbation of the copper transport system, which subsequently leads to deleterious conditions in cells. This study of the mechanism by which ceruloplasmin is modified by salsolinol may provide an explanation for the deterioration of organs under neurodegenerative disorders such as PD. [BMB Reports 2016; 49(1): 45-50] PMID:26077029

  17. Dioxygen Reactivity of Biomimetic Fe(II) Complexes with Noninnocent Catecholate, o-Aminophenolate, and o-Phenylenediamine Ligands

    PubMed Central

    2015-01-01

    This study describes the O2 reactivity of a series of high-spin mononuclear Fe(II) complexes each containing the facially coordinating tris(4,5-diphenyl-1-methylimidazol-2-yl)phosphine (Ph2TIP) ligand and one of the following bidentate, redox-active ligands: 4-tert-butylcatecholate (tBuCatH–), 4,6-di-tert-butyl-2-aminophenolate (tBu2APH–), or 4-tert-butyl-1,2-phenylenediamine (tBuPDA). The preparation and X-ray structural characterization of [Fe2+(Ph2TIP)(tBuCatH)]OTf, [3]OTf and [Fe2+(Ph2TIP)(tBuPDA)](OTf)2, [4](OTf)2 are described here, whereas [Fe2+(Ph2TIP)(tBu2APH)]OTf, [2]OTf was reported in our previous paper [Bittner et al., Chem.—Eur. J.2013,19, 9686–9698]. These complexes mimic the substrate-bound active sites of nonheme iron dioxygenases, which catalyze the oxidative ring-cleavage of aromatic substrates like catechols and aminophenols. Each complex is oxidized in the presence of O2, and the geometric and electronic structures of the resulting complexes were examined with spectroscopic (absorption, EPR, Mössbauer, resonance Raman) and density functional theory (DFT) methods. Complex [3]OTf reacts rapidly with O2 to yield the ferric-catecholate species [Fe3+(Ph2TIP)(tBuCat)]+ (3ox), which undergoes further oxidation to generate an extradiol cleavage product. In contrast, complex [4]2+ experiences a two-electron (2e–), ligand-based oxidation to give [Fe2+(Ph2TIP)(tBuDIBQ)]2+ (4ox), where DIBQ is o-diiminobenzoquinone. The reaction of [2]+ with O2 is also a 2e– process, yet in this case both the Fe center and tBu2AP ligand are oxidized; the resulting complex (2ox) is best described as [Fe3+(Ph2TIP)(tBu2ISQ)]+, where ISQ is o-iminobenzosemiquinone. Thus, the oxidized complexes display a remarkable continuum of electronic structures ranging from [Fe3+(L2–)]+ (3ox) to [Fe3+(L•–)]2+ (2ox) to [Fe2+(L0)]2+ (4ox). Notably, the O2 reaction rates vary by a factor of 105 across the series, following the order [3]+ > [2]+ > [4]2+, even though the

  18. The Catechol-O-Methyltransferase (COMT) val158met Polymorphism Affects Brain Responses to Repeated Painful Stimuli

    PubMed Central

    Gollub, Randy L.; Wasan, Ajay D.; Edwards, Robert R.; Kong, Jian

    2011-01-01

    Despite the explosion of interest in the genetic underpinnings of individual differences in pain sensitivity, conflicting findings have emerged for most of the identified “pain genes”. Perhaps the prime example of this inconsistency is represented by catechol-O-methyltransferase (COMT), as its substantial association to pain sensitivity has been reported in various studies, but rejected in several others. In line with findings from behavioral studies, we hypothesized that the effect of COMT on pain processing would become apparent only when the pain system was adequately challenged (i.e., after repeated pain stimulation). In the present study, we used functional Magnetic Resonance Imaging (fMRI) to investigate the brain response to heat pain stimuli in 54 subjects genotyped for the common COMT val158met polymorphism (val/val = n 22, val/met = n 20, met/met = n 12). Met/met subjects exhibited stronger pain-related fMRI signals than val/val in several brain structures, including the periaqueductal gray matter, lingual gyrus, cerebellum, hippocampal formation and precuneus. These effects were observed only for high intensity pain stimuli after repeated administration. In spite of our relatively small sample size, our results suggest that COMT appears to affect pain processing. Our data demonstrate that the effect of COMT on pain processing can be detected in presence of 1) a sufficiently robust challenge to the pain system to detect a genotype effect, and/or 2) the recruitment of pain-dampening compensatory mechanisms by the putatively more pain sensitive met homozygotes. These findings may help explain the inconsistencies in reported findings of the impact of COMT in pain regulation. PMID:22132136

  19. Bathochromic and stabilising effects of sugar beet pectin and an isolated pectic fraction on anthocyanins exhibiting pyrogallol and catechol moieties.

    PubMed

    Buchweitz, M; Carle, R; Kammerer, D R

    2012-12-15

    The formation of anthocyanin-metal chelates, exhibiting intense blue colours was monitored over a period up to 10 weeks. Evaluating normalised absorption spectra in the range of 580-700 nm and their proportion of the total area under the curve (AUC), provided information about the blue colour hue, intensity and stability. Colour stability in model solutions containing commercial sugar beet pectin or an isolated pectic polysaccharide fraction (PPF) therefrom, both being naturally enriched in aluminium and ferric ions, was assessed in a pH range of 3.6-7.0. The pectic structures stabilised anthocyanin-metal chelates, and thus blue colours by efficiently preventing complex precipitation. Highest bathochromic shifts and most intense blue colours were observed in PPF model solutions containing delphinidin-3-glucoside (Dpd-3-glc), exhibiting a pyrogallol moiety in the flavylium B-ring, compared to cyanidin- (Cyd-3-glc) and petunidin-3-glucoside (Pet-3-glc), both carrying a catechol substituted B-ring. Hue and intensity of the blue colour at pH 5.0 were only insignificantly influenced by the buffer system except for citrate and phosphate buffers, which both annihilated anthocyanin-metal chelate formation. The blue colours faded following first order kinetics. Best stabilities as deduced from storage experiments performed at 20 ± 2°C in the dark were observed for Dpd-3-glc. In contrast, Cyd-3-glc displayed shortened half-life values, whereas blue Pet-3-glc chelates decomposed rapidly. These results demonstrate that the solubilisation of anthocyanin-metal chelates by pectic structures is a promising option for developing water soluble natural blue food colourants.

  20. A self-assembled complex with a titanium(IV) catecholate core as a potential bimodal contrast agent.

    PubMed

    Dehaen, Geert; Eliseeva, Svetlana V; Kimpe, Kristof; Laurent, Sophie; Vander Elst, Luce; Muller, Robert N; Dehaen, Wim; Binnemans, Koen; Parac-Vogt, Tatjana N

    2012-01-01

    A ditopic chelating ligand (H(6)4) that bears catechol and diethylenetriamine-N,N,N',N'',N''-pentaacetate (DTPA) has been designed and shown to specifically bind lanthanide(III) ions at the DTPA core ([Ln(H(2)4)(H(2)O)](-)) and further self-assemble with titanium(IV), thereby giving rise to the formation of a supramolecular metallostar complex with a lanthanide(III)-to-titanium(IV) ratio of 3:1, [(Ln4)(3)Ti(H(2)O)(3)](5-) (Ln=La, Eu, Gd). The efficacy of the metallostar complex as a potential bimodal optical/magnetic resonance imaging (MRI) agent has been evaluated. Nuclear magnetic relaxation dispersion (NMRD) measurements for the [(Gd4)(3)Ti(H(2)O)(3)](5-) complex have demonstrated an enhanced r(1) relaxivity that corresponds to 36.9 s(-1) mM(-1) per metallostar molecule at 20 MHz and 310 K, which is a result of a decreased tumbling rate. The ability of the complex to bind to human serum albumin (HSA) was also examined by relaxometric measurements. In addition, upon UV irradiation the [(Gd4)(3)Ti(H(2)O)(3)](5-) complex exhibits broad-band green emission in the range 400-750 nm with a maximum at 490 nm. Taking into account the high relaxivity and luminescence properties, the [(Gd4)(3)Ti(H(2)O)(3)](5-) complex is a good lead compound for the development of efficient bimodal contrast agents.

  1. Affect-modulated startle: interactive influence of catechol-O-methyltransferase Val158Met genotype and childhood trauma.

    PubMed

    Klauke, Benedikt; Winter, Bernward; Gajewska, Agnes; Zwanzger, Peter; Reif, Andreas; Herrmann, Martin J; Dlugos, Andrea; Warrings, Bodo; Jacob, Christian; Mühlberger, Andreas; Arolt, Volker; Pauli, Paul; Deckert, Jürgen; Domschke, Katharina

    2012-01-01

    The etiology of emotion-related disorders such as anxiety or affective disorders is considered to be complex with an interaction of biological and environmental factors. Particular evidence has accumulated for alterations in the dopaminergic and noradrenergic system--partly conferred by catechol-O-methyltransferase (COMT) gene variation--for the adenosinergic system as well as for early life trauma to constitute risk factors for those conditions. Applying a multi-level approach, in a sample of 95 healthy adults, we investigated effects of the functional COMT Val158Met polymorphism, caffeine as an adenosine A2A receptor antagonist (300 mg in a placebo-controlled intervention design) and childhood maltreatment (CTQ) as well as their interaction on the affect-modulated startle response as a neurobiologically founded defensive reflex potentially related to fear- and distress-related disorders. COMT val/val genotype significantly increased startle magnitude in response to unpleasant stimuli, while met/met homozygotes showed a blunted startle response to aversive pictures. Furthermore, significant gene-environment interaction of COMT Val158Met genotype with CTQ was discerned with more maltreatment being associated with higher startle potentiation in val/val subjects but not in met carriers. No main effect of or interaction effects with caffeine were observed. Results indicate a main as well as a GxE effect of the COMT Val158Met variant and childhood maltreatment on the affect-modulated startle reflex, supporting a complex pathogenetic model of the affect-modulated startle reflex as a basic neurobiological defensive reflex potentially related to anxiety and affective disorders.

  2. Affect-Modulated Startle: Interactive Influence of Catechol-O-Methyltransferase Val158Met Genotype and Childhood Trauma

    PubMed Central

    Klauke, Benedikt; Winter, Bernward; Gajewska, Agnes; Zwanzger, Peter; Reif, Andreas; Herrmann, Martin J.; Dlugos, Andrea; Warrings, Bodo; Jacob, Christian; Mühlberger, Andreas; Arolt, Volker; Pauli, Paul; Deckert, Jürgen; Domschke, Katharina

    2012-01-01

    The etiology of emotion-related disorders such as anxiety or affective disorders is considered to be complex with an interaction of biological and environmental factors. Particular evidence has accumulated for alterations in the dopaminergic and noradrenergic system – partly conferred by catechol-O-methyltransferase (COMT) gene variation – for the adenosinergic system as well as for early life trauma to constitute risk factors for those conditions. Applying a multi-level approach, in a sample of 95 healthy adults, we investigated effects of the functional COMT Val158Met polymorphism, caffeine as an adenosine A2A receptor antagonist (300 mg in a placebo-controlled intervention design) and childhood maltreatment (CTQ) as well as their interaction on the affect-modulated startle response as a neurobiologically founded defensive reflex potentially related to fear- and distress-related disorders. COMT val/val genotype significantly increased startle magnitude in response to unpleasant stimuli, while met/met homozygotes showed a blunted startle response to aversive pictures. Furthermore, significant gene-environment interaction of COMT Val158Met genotype with CTQ was discerned with more maltreatment being associated with higher startle potentiation in val/val subjects but not in met carriers. No main effect of or interaction effects with caffeine were observed. Results indicate a main as well as a GxE effect of the COMT Val158Met variant and childhood maltreatment on the affect-modulated startle reflex, supporting a complex pathogenetic model of the affect-modulated startle reflex as a basic neurobiological defensive reflex potentially related to anxiety and affective disorders. PMID:22745815

  3. Modulation of brain structure by catechol-O-methyltransferase Val(158) Met polymorphism in chronic cannabis users.

    PubMed

    Batalla, Albert; Soriano-Mas, Carles; López-Solà, Marina; Torrens, Marta; Crippa, José A; Bhattacharyya, Sagnik; Blanco-Hinojo, Laura; Fagundo, Ana B; Harrison, Ben J; Nogué, Santiago; de la Torre, Rafael; Farré, Magí; Pujol, Jesús; Martín-Santos, Rocío

    2014-07-01

    Neuroimaging studies have shown that chronic consumption of cannabis may result in alterations in brain morphology. Recent work focusing on the relationship between brain structure and the catechol-O-methyltransferase (COMT) gene polymorphism suggests that functional COMT variants may affect brain volume in healthy individuals and in schizophrenia patients. We measured the influence of COMT genotype on the volume of four key regions: the prefrontal cortex, neostriatum (caudate-putamen), anterior cingulate cortex and hippocampus-amygdala complex, in chronic early-onset cannabis users and healthy control subjects. We selected 29 chronic cannabis users who began using cannabis before 16 years of age and matched them to 28 healthy volunteers in terms of age, educational level and IQ. Participants were male, Caucasians aged between 18 and 30 years. All were assessed by a structured psychiatric interview (PRISM) to exclude any lifetime Axis-I disorder according to Diagnostic and Statistical Manual for Mental Disorders-Fourth Edition. COMT genotyping was performed and structural magnetic resonance imaging data was analyzed by voxel-based morphometry. The results showed that the COMT polymorphism influenced the volume of the bilateral ventral caudate nucleus in both groups, but in an opposite direction: more copies of val allele led to lesser volume in chronic cannabis users and more volume in controls. The opposite pattern was found in left amygdala. There were no effects of COMT genotype on volumes of the whole brain or the other selected regions. Our findings support recent reports of neuroanatomical changes associated with cannabis use and, for the first time, reveal that these changes may be influenced by the COMT genotype.

  4. Differential Genetic and Epigenetic Regulation of catechol-O-methyltransferase is Associated with Impaired Fear Inhibition in Posttraumatic Stress Disorder

    PubMed Central

    Norrholm, Seth Davin; Jovanovic, Tanja; Smith, Alicia K.; Binder, Elisabeth; Klengel, Torsten; Conneely, Karen; Mercer, Kristina B.; Davis, Jennifer S.; Kerley, Kimberly; Winkler, Jennifer; Gillespie, Charles F.; Bradley, Bekh; Ressler, Kerry J.

    2013-01-01

    The catechol-O-methyltransferase (COMT) enzyme is critical for the catabolic regulation of synaptic dopamine, resulting in altered cortical functioning. The COMT Val158Met polymorphism has been implicated in human mental illness, with Met/Met homozygotes associated with increased susceptibility to posttraumatic stress disorder (PTSD). Our primary objective was to examine the intermediate phenotype of fear inhibition in PTSD stratified by COMT genotype (Met/Met, Val/Met, and Val/Val) and differential gene regulation via methylation status at CpG sites in the COMT promoter region. More specifically, we examined the potential interaction of COMT genotype and PTSD diagnosis on fear-potentiated startle during fear conditioning and extinction and COMT DNA methylation levels (as determined using genomic DNA isolated from whole blood). Participants were recruited from medical and gynecological clinics of an urban hospital in Atlanta, GA, USA. We found that individuals with the Met/Met genotype demonstrated higher fear-potentiated startle to the CS− (safety signal) and during extinction of the CS+ (danger signal) compared to Val/Met and Val/Val genotypes. The PTSD+ Met/Met genotype group had the greatest impairment in fear inhibition to the CS− (p = 0.006), compared to Val carriers. In addition, the Met/Met genotype was associated with DNA methylation at four CpG sites, two of which were associated with impaired fear inhibition to the safety signal. These results suggest that multiple differential mechanisms for regulating COMT function – at the level of protein structure via the Val158Met genotype and at the level of gene regulation via differential methylation – are associated with impaired fear inhibition in PTSD. PMID:23596403

  5. Association of Catechol-O-methyltransferase val/met polymorphism with cognitive function in Gilles de la Tourette syndrome patients.

    PubMed

    Ji, Weidong; Li, Ning; Ju, Kang; Zheng, Hong; Yang, Chuang; Xu, Ping; Chen, Silu; Cao, Aiai; Chen, Xue; Guo, Lanting

    2015-04-01

    Gilles de la Tourette syndrome (GTS) is a kind of neuropsychiatric disorder with childhood onset. The cognitive dysfunction caused by GTS could affect the growth and learning of children and adolescents. The mechanism of cognitive functions was associated with dopaminergic system, thus we access the associations between polymorphism of some dopaminergic system-related genes including Catechol-O-methyltransferase (COMT) met/val, Dopamine receptor D4 (DRD4) exon III 48 bp VNTR (variable number of tandem repeats), Interleukin 1 (IL-1) Ra 86 bp and IL-1β exon 5, and cognitive functions in GTS patients. Genotyping analysis was performed through polymerase chain reaction (PCR). Test for cognitive functions of GTS patients included modified wisconsin card sorting test (WCST), trail making test, visual reproduction test, stroop test and verbal fluency test. The patients with COMT met/met genotype showed less perseverative errors in modified WCST test compared with patients with COMT val/val genotype (P < 0.05). Meanwhile, patients without allele val had better delayed memory in visual reproduction test, less errors in the stroop test and less perseverative errors in modified WCST test compared with patients with allele val (P < 0.05). However, no significant difference was found in cognitive functions among patients with different genotypes or alleles of polymorphisms of DRD4 exon III 48 bp VNTR, IL-1 Ra 86 bp and IL-1β exon 5 (P > 0.05). Polymorphism of COMT met/val was correlated with cognitive functions in GTS patients. This study provided basis for the analysis of molecular genetic pathology of cognitive dysfunctions in GTS. PMID:25367405

  6. Electrochemical behavior of polypyrrol/AuNP composites deposited by different electrochemical methods: sensing properties towards catechol

    PubMed Central

    García-Hernández, Celia; Medina-Plaza, Cristina; Martín-Pedrosa, Fernando; Blanco, Yolanda; de Saja, José Antonio

    2015-01-01

    Summary Two different methods were used to obtain polypyrrole/AuNP (Ppy/AuNP) composites. One through the electrooxidation of the pyrrole monomer in the presence of colloidal gold nanoparticles, referred to as trapping method (T), and the second one by electrodeposition of both components from one solution containing the monomer and a gold salt, referred to as cogeneration method (C). In both cases, electrodeposition was carried out through galvanostatic and potentiostatic methods and using platinum (Pt) or stainless steel (SS) as substrates. Scanning electron microscopy (SEM) demonstrated that in all cases gold nanoparticles of similar size were uniformly dispersed in the Ppy matrix. The amount of AuNPs incorporated in the Ppy films was higher when electropolymerization was carried out by chronopotentiometry (CP). Besides, cogeneration method allowed for the incorporation of a higher number of AuNPs than trapping. Impedance experiments demonstrated that the insertion of AuNPs increased the conductivity. As an electrochemical sensor, the Ppy/AuNp deposited on platinum exhibited a strong electrocatalytic activity towards the oxidation of catechol. The effect was higher in films obtained by CP than in films obtained by chronoamperometry (CA). The influence of the method used to introduce the AuNPs (trapping or cogeneration) was not so important. The limits of detection (LOD) were in the range from 10−5 to 10−6 mol/L. LODs attained using films deposited on platinum were lower due to a synergy between AuNPs and platinum that facilitates the electron transfer, improving the electrocatalytic properties. Such synergistic effects are not so pronounced on stainless steel, but acceptable LOD are attained with lower price sensors. PMID:26665076

  7. Electrochemical behavior of polypyrrol/AuNP composites deposited by different electrochemical methods: sensing properties towards catechol.

    PubMed

    García-Hernández, Celia; García-Cabezón, Cristina; Medina-Plaza, Cristina; Martín-Pedrosa, Fernando; Blanco, Yolanda; de Saja, José Antonio; Rodríguez-Méndez, María Luz

    2015-01-01

    Two different methods were used to obtain polypyrrole/AuNP (Ppy/AuNP) composites. One through the electrooxidation of the pyrrole monomer in the presence of colloidal gold nanoparticles, referred to as trapping method (T), and the second one by electrodeposition of both components from one solution containing the monomer and a gold salt, referred to as cogeneration method (C). In both cases, electrodeposition was carried out through galvanostatic and potentiostatic methods and using platinum (Pt) or stainless steel (SS) as substrates. Scanning electron microscopy (SEM) demonstrated that in all cases gold nanoparticles of similar size were uniformly dispersed in the Ppy matrix. The amount of AuNPs incorporated in the Ppy films was higher when electropolymerization was carried out by chronopotentiometry (CP). Besides, cogeneration method allowed for the incorporation of a higher number of AuNPs than trapping. Impedance experiments demonstrated that the insertion of AuNPs increased the conductivity. As an electrochemical sensor, the Ppy/AuNp deposited on platinum exhibited a strong electrocatalytic activity towards the oxidation of catechol. The effect was higher in films obtained by CP than in films obtained by chronoamperometry (CA). The influence of the method used to introduce the AuNPs (trapping or cogeneration) was not so important. The limits of detection (LOD) were in the range from 10(-5) to 10(-6) mol/L. LODs attained using films deposited on platinum were lower due to a synergy between AuNPs and platinum that facilitates the electron transfer, improving the electrocatalytic properties. Such synergistic effects are not so pronounced on stainless steel, but acceptable LOD are attained with lower price sensors.

  8. Catechol-O-methyltransferase (COMT) genotype moderates the effects of childhood trauma on cognition and symptoms in schizophrenia.

    PubMed

    Green, Melissa J; Chia, T-Yunn; Cairns, Murray J; Wu, Jingqin; Tooney, Paul A; Scott, Rodney J; Carr, Vaughan J

    2014-02-01

    The interaction of genetic and environmental factors may affect the course and development of psychotic disorders. We examined whether the effects of childhood trauma on cognition and symptoms in schizophrenia were moderated by the Catechol-O-methyltransferase (COMT) Val(158)Met polymorphism, a common genetic variant known to affect cognition and prefrontal dopamine levels. Participants were 429 schizophrenia/schizoaffective cases from the Australian Schizophrenia Research Bank (ASRB). Cognitive performance was assessed using the Repeatable Battery for Assessment of Neuropsychological Status (RBANS), Controlled Oral Word Association Test (COWAT), Letter Number Sequencing (LNS) test, and the Wechsler Test of Adult Reading (WTAR). Hierarchical regression was used to test the main effects and additive interaction effects of genotype and childhood trauma in the domains of physical abuse, emotional abuse, and emotional neglect, on cognition and symptom profiles of clinical cases. Consistent with previous findings, COMT Val homozygotes performed worse on cognitive measures in the absence of childhood adversity. In addition, a significant interaction between COMT genotype and physical abuse was associated with better executive function in Val homozygotes, relative to those of the same genotype with no history of abuse. Finally, the severity of positive symptoms was greater in Met carriers who had experienced physical abuse, and the severity of negative symptoms in Met carriers was greater in the presence of emotional neglect. These results suggest that the possible epigenetic modulation of the expression of the COMT Val(158)Met polymorphism and consequent effects on cognition and symptoms in schizophrenia, with worse outcomes associated with adverse childhood experiences in Met carriers.

  9. Modulation of catechol estrogen synthesis by rat liver microsomes: effects of treatment with growth hormone or testosterone

    SciTech Connect

    Quail, J.A.; Jellinck, P.H.

    1987-09-01

    The ability of GH from various mammalian species, administered to normal mature male rats by constant infusion, to decrease the hepatic 2-hydroxylation of estradiol (E2) to female levels, as measured by the release of /sup 3/H/sub 2/O from (2-3H)E2, was determined. Rat and human GH (hGH) showed the highest activity while ovine GH was inactive. PRL (0.6 IU/h X kg) administered together with hGH (0.02 IU/h X kg) did not antagonize the feminizing action of GH. Infusion of hGH into male rats decreased the affinity of estradiol 2-hydroxylase for its steroid substrate and altered the linear Lineweaver-Burk plot towards a nonlinear hyperbolic plot characteristic of the female. The apparent Michaelis-Menten constant (Km) for the reaction was 1.69 microM for males and 2.75 microM for testosterone-treated ovariectomized females. An equal mixture of liver microsomes from male and female rats gave kinetic values similar to those observed with males alone. Neonatal imprinting with androgen did not alter the magnitude of the response of female rats to treatment with testosterone and/or GH at maturity and the androgen effect could only be shown in ovariectomized animals. The results with rats of different endocrine status were corroborated by the kinetic data and by the pattern of metabolites obtained with (4-/sup 14/C)E2 when examined by TLC and autoradiography. The hormonal control of estradiol 2-hydroxylase, the key enzyme in catechol estrogen formation, and the contribution of sex-specific multiple forms of the enzyme to this reaction are discussed.

  10. Formation of aromatic compounds from carbohydrates. X reaction of xylose, glucose, and glucuronic acid in acidic solution at 300C

    SciTech Connect

    Theander, O.; Nelson, D.A.; Hallen, R.T.

    1987-04-01

    For several years our respective groups have investigated the formation of aromatic compounds from carbohydrates in aqueous solution at various pH-values under reflux or hydrothermolytic conditions. For instance, previous papers in this series concerned the degradation of hexoses, pentoses, erythrose, dihydroxyacetone, and hexuronic acids to phenolic and enolic components. Of particular interest were the isolation and identification of catechols, an acetophenone, and chromones from pentoses and hexuronic acids at pH 4.5. The formation of these compounds, as well as reductic acid, was found to be more pronounced than that of 2-furaldehyde under acidic conditions. The aromatic precursors of 3 and 4 were also isolated from these reaction mixtures. This is in contrast to the high yields of 2 obtained from pentoses and hexuronic acids at very low pH.

  11. Metabolism of 2-hydroxy-1-naphthoic acid and naphthalene via gentisic acid by distinctly different sets of enzymes in Burkholderia sp. strain BC1.

    PubMed

    Chowdhury, Piyali Pal; Sarkar, Jayita; Basu, Soumik; Dutta, Tapan K

    2014-05-01

    Burkholderia sp. strain BC1, a soil bacterium, isolated from a naphthalene balls manufacturing waste disposal site, is capable of utilizing 2-hydroxy-1-naphthoic acid (2H1NA) and naphthalene individually as the sole source of carbon and energy. To deduce the pathway for degradation of 2H1NA, metabolites isolated from resting cell culture were identified by a combination of chromatographic and spectrometric analyses. Characterization of metabolic intermediates, oxygen uptake studies and enzyme activities revealed that strain BC1 degrades 2H1NA via 2-naphthol, 1,2,6-trihydroxy-1,2-dihydronaphthalene and gentisic acid. In addition, naphthalene was found to be degraded via 1,2-dihydroxy-1,2-dihydronaphthalene, salicylic acid and gentisic acid, with the putative involvement of the classical nag pathway. Unlike most other Gram-negative bacteria, metabolism of salicylic acid in strain BC1 involves a dual pathway, via gentisic acid and catechol, with the latter being metabolized by catechol 1,2-dioxygenase. Involvement of a non-oxidative decarboxylase in the enzymic transformation of 2H1NA to 2-naphthol indicates an alternative catabolic pathway for the bacterial degradation of hydroxynaphthoic acid. Furthermore, the biochemical observations on the metabolism of structurally similar compounds, naphthalene and 2-naphthol, by similar but different sets of enzymes in strain BC1 were validated by real-time PCR analyses.

  12. The Influence of the Val158Met Catechol-O-Methyltransferase Polymorphism on the Personality Traits of Bipolar Patients

    PubMed Central

    Dávila, Wendy; Basterreche, Nieves; Arrue, Aurora; Zamalloa, María I.; Gordo, Estíbaliz; Dávila, Ricardo; González-Torres, Miguel A.; Zumárraga, Mercedes

    2013-01-01

    Introduction Certain personality traits and genetic polymorphisms are contributing factors to bipolar disorder and its symptomatology, and in turn, this syndrome influences personality. The aim of the present study is to compare the personality traits of euthymic bipolar patients with healthy controls and to investigate the effect of the catechol-O-methyltransferase (COMT) Val158Met genotype on those traits. We recruited thirty seven bipolar I patients in euthymic state following a manic episode and thirty healthy controls and evaluated their personality by means of the Cloninger’s Temperament and Character Inventory (version TCI-R-140). We assessed the influence of the polymorphism Val158Met in the COMT gene on the personality of these patients. The patients scored higher than controls in harm avoidance (61.3±12.5 vs. 55.3±8.1) and self-transcendence (45.3±12.8 vs. 32.7±8.2) and scored lower than controls in self-directedness (68.8±13.3 vs. 79.3±8.1), cooperativeness (77.1±9.1 vs. 83.9±6.5) and persistence (60.4±15.1 vs. 67.1±8.9). The novelty seeking dimension associates with the Val158Met COMT genotype; patients with the low catabolic activity genotype, Met/Met, show a higher score than those with the high catabolic activity genotype, Val/Val. Conclusions Suffering from bipolar disorder could have an impact on personality. A greater value in harm avoidance may be a genetic marker for a vulnerability to the development of a psychiatric disorder, but not bipolar disorder particularly, while a low value in persistence may characterize affective disorders or a subgroup of bipolar patients. The association between novelty seeking scores and COMT genotype may be linked with the role dopamine plays in the brain’s reward circuits. PMID:23646156

  13. Chelating agents for uranium(IV): 2. Efficacy and toxicity of tetradentate catecholate and hydroxypyridinonate ligands in mice

    SciTech Connect

    Durbin, P.W.; Kullgren, B.; Ebbe, S.N.; Xu, J.; Raymond, K.N.

    2000-05-01

    Uranium(VI) (UO{sub 2}{sup 2+}, uranyl) is nephrotoxic. Depending on isotopic composition and dosage, U(VI) is also chemically toxic and carcinogenic in bone. Several ligands containing two, three, or four bidentate catecholate or hydroxypyridinonate metal binding groups, developed for in vivo chelation of other actinides, were found, on evaluation in mice, to be effective for in vivo chelation of U(VI). The most promising ligands contained two bidentate groups per chelator molecule (tetradentate) attached to linear 4- or 5-carbon backbones (4-LI, butylene; 5-LI, pentylene; 5-LIO, diethyl ether). New ligands were then prepared to optimize ligand affinity for U(VI) in vivo and low acute toxicity. Five bidentate binding groups--sulfocatechol [CAM(S)], carboxycatechol [CAM(C)], methylterephthalamide (MeTAM), 1,2-hydroxypyridinone (1,2-HOPO), or 3,2-hydroxypyridinone (Me-3,2-HOPO)--were each attached to two linear backbones (4-LI and 5-LI or 5-LIO). Those ten tetradentate ligands and octadentate 3,4,3-LI(1,2-HOPO), an effective actinide chelator, were evaluated in mice for in vivo chelation of {sup 233}U(VI) (injection at 3 min, 1 h, or 24 h or oral administration at 3 min after intravenous injection of {sup 233}UO{sub 2}Cl{sub 2}) and for acute toxicity (100 {micro}mol kg{sup {minus}1} injected daily for 10 d). The combined efficacy and toxicity screening identified 5-LIO(Me-3,2-HOPO) and 5-LICAM(S) as the most effective low-toxicity agents. They chelate circulating U(VI) efficiently at ligand:uranium molar ratios {ge} 20, remove useful amounts of newly deposited U(VI) from kidney and bone at molar ratios {ge} 100, and reduce kidney U(VI) levels significantly when given orally at molar ratios {ge} 100. 5-LIO(Me-3,2-HOPO) has greater affinity for kidney U(VI) while 5-LICAM(S) has greater affinity for bone U(VI), and a 1:1 mixture (total molar ratio = 91) reduced kidney and bone U(VI) to 15 and 58% of control, respectively--more than an equimolar amount of either ligand

  14. New avenues for ligand-mediated processes--expanding metal reactivity by the use of redox-active catechol, o-aminophenol and o-phenylenediamine ligands.

    PubMed

    Broere, Daniël L J; Plessius, Raoul; van der Vlugt, Jarl Ivar

    2015-10-01

    Redox-active ligands have evolved from being considered spectroscopic curiosities - creating ambiguity about formal oxidation states in metal complexes - to versatile and useful tools to expand on the reactivity of (transition) metals or to even go beyond what is generally perceived possible. This review focusses on metal complexes containing either catechol, o-aminophenol or o-phenylenediamine type ligands. These ligands have opened up a new area of chemistry for metals across the periodic table. The portfolio of ligand-based reactivity invoked by these redox-active entities will be discussed. This ranges from facilitating oxidative additions upon d(0) metals or cross coupling reactions with cobalt(iii) without metal oxidation state changes - by functioning as an electron reservoir - to intramolecular ligand-to-substrate single-electron transfer to create a reactive substrate-centered radical on a Pd(ii) platform. Although the current state-of-art research primarily consists of stoichiometric and exploratory reactions, several notable reports of catalysis facilitated by the redox-activity of the ligand will also be discussed. In conclusion, redox-active ligands containing catechol, o-aminophenol or o-phenylenediamine moieties show great potential to be exploited as reversible electron reservoirs, donating or accepting electrons to activate substrates and metal centers and to enable new reactivity with both early and late transition as well as main group metals. PMID:26148803

  15. Effects of Temperature and pH on the Activities of Catechol 2,3-dioxygenase Obtained from Crude Oil Contaminated Soil in Ilaje, Ondo State, Nigeria

    PubMed Central

    Olukunle, O.F.; Babajide, O.; Boboye, B.

    2015-01-01

    Enrichment technique was employed for the isolation of the crude oil degrading bacteria. The isolated bacteria were screened for their degradative ability and the best degrading bacteria were selected based on their growth. Specific activities of Catechol-2,3-dioxygenase and effects of temperature and pH and their stabilities on the enzyme relative activities were observed. Bacteria isolated from the soil sample include; Bacillus cereus, B. amyloliquficiens, B. firmus, Acinetobacter calcoaceticus, Pseudomonas sp. P. fluorescens, P.putida, P.aeruginosa, Achromobacter xylosoxidans and Achromobacter sp. Screening of the degradative ability of the bacteria revealed P. aeruginosa, Bacillus cereus, Acinetobacter calcoaceticus and Achromobacter sp. to be the best degraders. The pH and temperature range with time for the enzyme activity were 6.0-8.0 and 30oC-50oC respectively. The enzyme exhibited activity that was slightly more tolerant to alkaline pH. Therefore, engineering of Catechol 2,3-dioxygenase may be employed for application on bioremediation of polluted sites. PMID:26464607

  16. Effects of surface hydrophobicity on the catalytic iron ion retention in the active site of two catechol 1,2-dioxygenase isoenzymes.

    PubMed

    Di Nardo, Giovanna; Pessione, Enrica; Cavaletto, Maria; Anfossi, Laura; Vanni, Adriano; Briganti, Fabrizio; Giunta, Carlo

    2004-12-01

    The different behaviour of two isozymes (IsoA and IsoB) of catechol 1,2-dioxygenase (C 1,20) from Acinetobacter radioresistens S13 on a hydrophobic interaction, Phenyl-Sepharose chromatographic column, prompted us to investigate the role of superficial hydrophobicity on structural-functional aspects for such class of enzymes. The interaction of 8-anilino-1-naphtalenesulphonate (ANS), a fluorescent probe known to bind to hydrophobic sites in proteins, revealed that the two isoenzymes have a markedly different hydrophobicity degree although a similar number of hydrophobic superficial sites were estimated (2.65 for IsoA and 2.18 for IsoB). ANS is easily displaced by adding the substrates catechol or 3-methylcatechol to the adduct, suggesting that the binding sites are in the near surroundings of the catalytic clefts. The analysis of the hydropathy profiles and the possible superficial cavities allowed to recognize the most feasible region for ANS binding. The lower hydrophobicity detected in the near surroundings of the catalytic pocket of IsoB supports its peculiarity to lose the catalytic metal ions more easily than IsoA. As previously suggested for other metalloenzymes, the presence of more hydrophilic and/or smaller residues near to the active site of IsoB is expected to increase the metal ligands mobility thus increasing the metal ion dissociation rate constants, estimated to be 0.078 h(-1) and 0.670 h(-1) for IsoA and IsoB respectively.

  17. Assessment of toxicological interactions of benzene and its primary degradation products (catechol and phenol) using a lux-modified bacterial bioassay

    SciTech Connect

    Boyd, E.M. |; Meharg, A.A.; Wright, J.; Killham, K.

    1997-05-01

    A bacterial bioassay has been developed to assess the relative toxicities of xenobiotics commonly found in contaminated soils, river waters, and ground waters. The assay utilized decline in luminescence of lux-marked Pseudomonas fluorescens on exposure to xenobiotics. Pseudomonas fluorescens is a common bacterium in the terrestrial environment, providing environmental relevance to soil, river, and ground water systems. Three principal environmental contaminants associated with benzene degradation were exposed to the luminescence-marked bacterial biosensor to assess their toxicity individually and in combination. Median effective concentration (EC50) values for decline in luminescence were determined for benzene, catechol, and phenol and were found to be 39.9, 0.77, and 458.6 mg/L, respectively. Catechol, a fungal and bacterial metabolite of benzene, was found to be significantly more toxic to the biosensor than was the parent compound benzene, showing that products of xenobiotic biodegradation may be more toxic than the parent compounds. Combinations of parent compounds and metabolites were found to be significantly more toxic to the bioassay than were the individual compounds themselves. Development of this bioassay has provided a rapid screening system suitable for assessing the toxicity of xenobiotics commonly found in contaminated soil, river, and ground-water environments. The assay can be utilized over a wide pH range is therefore more applicable to such environmental systems than bioluminescence-based bioassays that utilize marine organisms and can only be applied over a limited pH and salinity range.

  18. Effects of Temperature and pH on the Activities of Catechol 2,3-dioxygenase Obtained from Crude Oil Contaminated Soil in Ilaje, Ondo State, Nigeria.

    PubMed

    Olukunle, O F; Babajide, O; Boboye, B

    2015-01-01

    Enrichment technique was employed for the isolation of the crude oil degrading bacteria. The isolated bacteria were screened for their degradative ability and the best degrading bacteria were selected based on their growth. Specific activities of Catechol-2,3-dioxygenase and effects of temperature and pH and their stabilities on the enzyme relative activities were observed. Bacteria isolated from the soil sample include; Bacillus cereus, B. amyloliquficiens, B. firmus, Acinetobacter calcoaceticus, Pseudomonas sp. P. fluorescens, P.putida, P.aeruginosa, Achromobacter xylosoxidans and Achromobacter sp. Screening of the degradative ability of the bacteria revealed P. aeruginosa, Bacillus cereus, Acinetobacter calcoaceticus and Achromobacter sp. to be the best degraders. The pH and temperature range with time for the enzyme activity were 6.0-8.0 and 30(o)C-50(o)C respectively. The enzyme exhibited activity that was slightly more tolerant to alkaline pH. Therefore, engineering of Catechol 2,3-dioxygenase may be employed for application on bioremediation of polluted sites. PMID:26464607

  19. Surface-Sensitive and Bulk Studies on the Complexation and Photosensitized Degradation of Catechol by Iron(III) as a Model for Multicomponent Aerosol Systems

    NASA Astrophysics Data System (ADS)

    Al-abadleh, H. A.; Tofan-Lazar, J.; Situm, A.; Ruffolo, J.; Slikboer, S.

    2013-12-01

    Surface water plays a crucial role in facilitating or inhibiting surface reactions in atmospheric aerosols. Little is known about the role of surface water in the complexation of organic molecules to transition metals in multicomponent aerosol systems. We will show results from real time diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments for the in situ complexation of catechol to Fe(III) and its photosensitized degradation under dry and humid conditions. Catechol was chosen as a simple model for humic-like substances (HULIS) in aerosols and aged polyaromatic hydrocarbons (PAH). It has also been detected in secondary organic aerosols (SOA) formed from the reaction of hydroxyl radicals with benzene. Given the importance of the iron content in aerosols and its biogeochemistry, our studies were conducted using FeCl3. For comparison, these surface-sensitive studies were complemented with bulk aqueous ATR-FTIR, UV-vis, and HPLC measurements for structural, quantitative and qualitative information about complexes in the bulk, and potential degradation products. The implications of our studies on understanding interfacial and condensed phase chemistry relevant to multicomponent aerosols, water thin islands on buildings, and ocean surfaces containing transition metals will be discussed.

  20. New avenues for ligand-mediated processes--expanding metal reactivity by the use of redox-active catechol, o-aminophenol and o-phenylenediamine ligands.

    PubMed

    Broere, Daniël L J; Plessius, Raoul; van der Vlugt, Jarl Ivar

    2015-10-01

    Redox-active ligands have evolved from being considered spectroscopic curiosities - creating ambiguity about formal oxidation states in metal complexes - to versatile and useful tools to expand on the reactivity of (transition) metals or to even go beyond what is generally perceived possible. This review focusses on metal complexes containing either catechol, o-aminophenol or o-phenylenediamine type ligands. These ligands have opened up a new area of chemistry for metals across the periodic table. The portfolio of ligand-based reactivity invoked by these redox-active entities will be discussed. This ranges from facilitating oxidative additions upon d(0) metals or cross coupling reactions with cobalt(iii) without metal oxidation state changes - by functioning as an electron reservoir - to intramolecular ligand-to-substrate single-electron transfer to create a reactive substrate-centered radical on a Pd(ii) platform. Although the current state-of-art research primarily consists of stoichiometric and exploratory reactions, several notable reports of catalysis facilitated by the redox-activity of the ligand will also be discussed. In conclusion, redox-active ligands containing catechol, o-aminophenol or o-phenylenediamine moieties show great potential to be exploited as reversible electron reservoirs, donating or accepting electrons to activate substrates and metal centers and to enable new reactivity with both early and late transition as well as main group metals.

  1. Evaluation of Mut(S) and Mut⁺ Pichia pastoris strains for membrane-bound catechol-O-methyltransferase biosynthesis.

    PubMed

    Pedro, A Q; Oppolzer, D; Bonifácio, M J; Maia, C J; Queiroz, J A; Passarinha, L A

    2015-04-01

    Catechol-O-methyltransferase (COMT, EC 2.1.1.6) is an enzyme that catalyzes the methylation of catechol substrates, and while structural and functional studies of its membrane-bound isoform (MBCOMT) are still hampered by low recombinant production, Pichia pastoris has been described as an attractive host for the production of correctly folded and inserted membrane proteins. Hence, in this work, MBCOMT biosynthesis was developed using P. pastoris X33 and KM71H cells in shake flasks containing a semidefined medium with different methanol concentrations. Moreover, after P. pastoris glass beads lysis, biologically and immunologically active hMBCOMT was found mainly in the solubilized membrane fraction whose kinetic parameters were identical to its correspondent native enzyme. In addition, mixed feeds of methanol and glycerol or sorbitol were also employed, and its levels quantified using liquid chromatography coupled to refractive index detection. Overall, for the first time, two P. pastoris strains with opposite phenotypes were applied for MBCOMT biosynthesis under the control of the strongly methanol-inducible alcohol oxidase (AOX) promoter. Moreover, this eukaryotic system seems to be a promising approach to deliver MBCOMT in high quantities from fermentor cultures with a lower cost-benefit due to the cheaper cultivation media coupled with the higher titers tipically achieved in biorreactors, when compared with previously reported mammallian cell cultures. PMID:25712908

  2. Protective activity of the Uncaria tomentosa extracts on human erythrocytes in oxidative stress induced by 2,4-dichlorophenol (2,4-DCP) and catechol.

    PubMed

    Bors, Milena; Bukowska, Bożena; Pilarski, Radosław; Gulewicz, Krzysztof; Oszmiański, Jan; Michałowicz, Jaromir; Koter-Michalak, Maria

    2011-09-01

    The purpose of this study was to evaluate the effect of the ethanolic and aqueous extracts of Uncaria tomentosa on human erythrocytes and additionally the assessment of protective effect of these extracts on hemolysis induction, hemoglobin oxidation, and changes in the level of reactive oxygen species (ROS) and lipid peroxidation, which were provoked by selected xenobiotics, i.e. 2,4-dichlorophenol (2,4-DCP) and catechol. All tested extracts, even at a very high concentration of 500 μg/ml were not toxic to the erythrocytes because they did not cause lipid peroxidation, increase methemoglobin and ROS levels nor provoked hemolysis. The results of this study also revealed protective effect of extracts of U. tomentosa. The extracts studied depleted the extent of hemoglobin oxidation and lipid peroxidation as well as decreased the level of ROS and hemolysis, which was provoked by 2,4-DCP. No protective activity of the extracts against catechol action, which is a precursor of semiquinones in cell was found. A difference in the effect of the extracts studied was observed. Ethanol-based extracts revealed more pronounced ability to inhibit oxidation processes in human erythrocytes.

  3. Quantification of subfamily I.2.C catechol 2,3-dioxygenase mRNA transcripts in groundwater samples of an oxygen-limited BTEX-contaminated site.

    PubMed

    Táncsics, András; Szoboszlay, Sándor; Szabó, István; Farkas, Milán; Kovács, Balázs; Kukolya, József; Mayer, Zoltán; Kriszt, Balázs

    2012-01-01

    Low dissolved oxygen concentration of subsurface environments is a limiting factor for microbial aromatic hydrocarbon degradation, and to date, there are only a limited number of available reports on functional genes and microbes that take part in the degradation of aromatic hydrocarbons under hypoxic conditions. Recent discoveries shed light on the prevalence of subfamily I.2.C catechol 2,3-dioxygenases in petroleum hydrocarbon contaminated hypoxic groundwaters, and their considerable environmental importance was suggested. Here, we report on a Hungarian aromatic hydrocarbon (methyl-substituted benzene derivatives, mostly xylenes) contaminated site where we investigated this presumption. Groundwater samples were taken from the center and the edge of the contaminant plume and beyond the plume. mRNA transcripts of subfamily I.2.C catechol 2,3-dioxygenases were detected in considerable amounts in the contaminated samples by qPCR analysis, while activity of subfamily I.2.A, which includes the largest group of extradiol dioxygenases described by culture-dependent studies and thought to be widely distributed in BTEX-contaminated environments, was not observed. Bacterial community structure analyses showed the predominance of genus Rhodoferax related species in the contaminated samples.

  4. Catechol-O-methyltransferase (COMT) gene variants: possible association of the Val158Met variant with opiate addiction in Hispanic women.

    PubMed

    Oosterhuis, Bronson E; LaForge, K Steven; Proudnikov, Dmitri; Ho, Ann; Nielsen, David A; Gianotti, Robert; Barral, Sandra; Gordon, Derek; Leal, Suzanne M; Ott, Jurg; Kreek, Mary Jeanne

    2008-09-01

    Catechol-O-methyltransferase (COMT) catalyzes the breakdown of catechol neurotransmitters, including dopamine, which plays a prominent role in drug reward. A common single nucleotide polymorphism (SNP), G472A, codes for a Val158Met substitution and results in a fourfold down regulation of enzyme activity. We sequenced exon IV of COMT gene in search for novel polymorphisms and then genotyped four out of five identified by direct sequencing, using TaqMan assay on 266 opioid-dependent and 173 control subjects. Genotype frequencies of the G472A SNP varied significantly (P = 0.029) among the three main ethnic/cultural groups (Caucasians, Hispanics, and African Americans). Using a genotype test, we found a trend to point-wise association (P = 0.053) of the G472A SNP in Hispanic subjects with opiate addiction. Further analysis of G472A genotypes in Hispanic subjects with data stratified by gender identified a point-wise significant (P = 0.049) association of G/A and A/A genotypes with opiate addiction in women, but not men. These point-wise significant results are not significant experiment-wise (at P < 0.05) after correction for multiple testing. No significant association was found with haplotypes of the three most common SNPs. Linkage disequilibrium patterns were similar for the three ethnic/cultural groups.

  5. [Effect of calcium cations on acid-base properties and free radical oxidation of dopamine and pyrocatechol].

    PubMed

    Lebedev, A V; Ivanova, M V; Timoshin, A A; Ruuge, E K

    2008-01-01

    Ca2+-induced increase in the rate of pyrocatechol and dopamine oxidation by dioxygen and Ca2+-dependent acid-base properties of the catechols were studied by potentiometric titration, UV/Vis-spectrophotometry, EPR-spectroscopy, and by measurement of oxygen consumption. The effect of Ca2+ on the chain reactions of oxidation can be explained by additional deprotonation (decrease in pKai) of the catechols that accelerates one electron transport to dioxygen and formation of calcium semiquinonate, undergoing further oxidation. The described Ca2+-dependent redox-conversion of ortho-phenols proposes that an additional function of calcium in the cell can be its involvement in free radical oxidoreductive reactions at pH > pKai.

  6. The metabolism of aromatic acids by micro-organisms. Metabolic pathways in the fungi

    PubMed Central

    Cain, R. B.; Bilton, R. F.; Darrah, Josephine A.

    1968-01-01

    1. The metabolic pathways of aromatic-ring fission were examined in a range of fungal genera that utilize several compounds related to lignin. 2. Most of the genera, after growth on p-hydroxybenzoate, protocatechuate or compounds that are degraded to the latter (e.g. caffeate, ferulate or vanillate), rapidly oxidized these compounds, but not catechol. 3. Such genera possessed a protocatechuate 3,4-oxygenase and accumulated β-carboxymuconate as the product of protocatechuate oxidation. This enzyme had a high pH optimum in most organisms; the Rhodotorula enzyme was competitively inhibited by catechol. 4. β-Carboxymuconate was converted by all competent fungi into β-carboxymuconolactone, which was isolated and characterized. None of the fungi produced or utilized at significant rates the corresponding bacterial intermediate γ-carboxymuconolactone. 5. The lactonizing enzymes of Rhodotorula and Neurospora crassa had a pH optimum near 5·5 and approximate molecular weights of 19000 and 190000 respectively. 6. The fungi did not degrade the isomeric (+)-muconolactone, γ-carboxymethylenebutanolide or β-oxoadipate enol lactone at significant rates, and thus differ radically from bacteria, where β-oxoadipate enol lactone is the precursor of β-oxoadipate in all strains examined. 7. The end product of β-carboxymuconolactone metabolism by extracts was β-oxoadipate. 8. Evidence for a coenzyme A derivative of β-oxoadipate was found during further metabolism of this keto acid. 9. A few anomalous fungi, after growth on p-hydroxybenzoate, had no protocatechuate 3,4-oxygenase, but possessed all the enzymes of the catechol pathway. Catechol was detected in the growth medium in one instance. 10. A strain of Penicillium sp. formed pyruvate but no β-oxoadipate from protocatechuate, suggesting the existence also of a `meta' type of ring cleavage among fungi. PMID:5691754

  7. The Flexible Mind Is Associated with the Catechol-O-Methyltransferase (COMT) Val[superscript 158]Met Polymorphism: Evidence for a Role of Dopamine in the Control of Task-Switching

    ERIC Educational Resources Information Center

    Colzato, Lorenza S.; Waszak, Florian; Nieuwenhuis, Sander; Posthuma, Danielle; Hommel, Bernhard

    2010-01-01

    Genetic variability related to the catechol-O-methyltransferase (COMT) gene Val[superscript 128]Met polymorphism) has received increasing attention as a possible modulator of cognitive control functions. Recent evidence suggests that the Val[superscript 128]Met genotype may differentially affect cognitive stability and flexibility, in such a way…

  8. Oxidation of benzene to phenol, catechol, and 1,2,3-trihydroxybenzene by toluene 4-monooxygenase of Pseudomonas mendocina KR1 and toluene 3-monooxygenase of Ralstonia pickettii PKO1.

    PubMed

    Tao, Ying; Fishman, Ayelet; Bentley, William E; Wood, Thomas K

    2004-07-01

    Aromatic hydroxylations are important bacterial metabolic processes but are difficult to perform using traditional chemical synthesis, so to use a biological catalyst to convert the priority pollutant benzene into industrially relevant intermediates, benzene oxidation was investigated. It was discovered that toluene 4-monooxygenase (T4MO) of Pseudomonas mendocina KR1, toluene 3-monooxygenase (T3MO) of Ralstonia pickettii PKO1, and toluene ortho-monooxygenase (TOM) of Burkholderia cepacia G4 convert benzene to phenol, catechol, and 1,2,3-trihydroxybenzene by successive hydroxylations. At a concentration of 165 microM and under the control of a constitutive lac promoter, Escherichia coli TG1/pBS(Kan)T4MO expressing T4MO formed phenol from benzene at 19 +/- 1.6 nmol/min/mg of protein, catechol from phenol at 13.6 +/- 0.3 nmol/min/mg of protein, and 1,2,3-trihydroxybenzene from catechol at 2.5 +/- 0.5nmol/min/mg of protein. The catechol and 1,2,3-trihydroxybenzene products were identified by both high-pressure liquid chromatography and mass spectrometry. When analogous plasmid constructs were used, E. coli TG1/pBS(Kan)T3MO expressing T3MO formed phenol, catechol, and 1,2,3-trihydroxybenzene at rates of 3 +/- 1, 3.1 +/- 0.3, and 0.26 +/- 0.09 nmol/min/mg of protein, respectively, and E. coli TG1/pBS(Kan)TOM expressing TOM formed 1,2,3-trihydroxybenzene at a rate of 1.7 +/- 0.3 nmol/min/mg of protein (phenol and catechol formation rates were 0.89 +/- 0.07 and 1.5 +/- 0.3 nmol/min/mg of protein, respectively). Hence, the rates of synthesis of catechol by both T3MO and T4MO and the 1,2,3-trihydroxybenzene formation rate by TOM were found to be comparable to the rates of oxidation of the natural substrate toluene for these enzymes (10.0 +/- 0.8, 4.0 +/- 0.6, and 2.4 +/- 0.3 nmol/min/mg of protein for T4MO, T3MO, and TOM, respectively, at a toluene concentration of 165 microM). PMID:15240250

  9. Effects of garlic on cellular doubling time and DNA strand breaks caused by UV light and BPL, enhanced with catechol and TPA

    SciTech Connect

    Baturay, N.Z.; Gayle, F.; Liu, S.; Kreidinger, C.

    1995-11-01

    3T3 cell cultures were exposed to UV light and Beta-Propiolactone. Neoplastic cell transformation (TF) was demonstrated after concurrent addition of catechol, or repeated addition of TPA. Addition of garlic to all fluences/concentrations of the carcinogen/cocarcinogen/promoter groups reduced the number of transformed foci/dish by at least 40%. Since the cell cycle is prolonged following exposure to carcinogens, it is likely the cell requires a longer time to repair this damage. The doubling time (DT) was extended from 12 to 36 hrs. when cells were exposed to BPL and from 12 o 28 hrs. when cells were exposed to 3.0J/M2/sec. If an anticarcinogenic compound is also added, it is reasonable to assume that the cell cycle may be further elongated. The cell cycle, denoted by DT was lengthened from 12 to 47 hrs and from 12 to 86 hrs for BPL and UVC, respectively. The extensions occurred in a dope dependent manner. The concentrations of the cocarcinogen and promoter remained constant throughout the experiment. When strand breaks were determined at the same dose sequences, by alkaline elution, more repair was seen with garlic where the lowest and middle doses of BPL were used and almost no decrease in % DNA eluted was seen with UVC exposed cells. With catechol, there was a two-fold decrease in % DNA eluted at the lowest and middle fluences. When TPA was added, all three fluences of UVC showed more than a threefold decrease in % DNA eluted. BPS with both TPA and catechol, again showed a reduction in strand breaks only low and middle doses. Both a direct-acting alkylating agent, BPL, and a physical carcinogen, UVC, were homogeneously affected, in terms of doubling time, but not when strand break repair was examined. A separate mechanism may be responsible for repair, and the mechanism associated with combinations of physical carcinogen enhancing agents combined with some non-carcinogens may be more profoundly affected by some natural products.

  10. Genetic polymorphisms of estrogen receptor alpha and catechol-O-methyltransferase genes in Turkish patients with familial prostate carcinoma

    PubMed Central

    Pazarbasi, Ayfer; Yilmaz, M. Bertan; Alptekin, Davut; Luleyap, Umit; Tansug, Zuhtu; Ozpak, Lutfiye; Izmirli, Muzeyyen; Onatoglu-Arikan, Dilge; Kocaturk-Sel, Sabriye; Erkoc, Mehmet Ali; Turgut, Ozgur; Bereketoglu, Ceyhun; Tunc, Erdal; Akbal, Eylul

    2013-01-01

    OBJECTIVES: Estrogen is one of the most crucial hormones participating in the proliferation and carcinogenesis of the prostate glands. Genetic polymorphisms in the estrogen metabolism pathway might be involved in the risk of prostate carcinoma development. We evaluated the association between genetic polymorphisms in estrogen receptor alpha (ESR1) and catechol-O-methyltransferase (COMT) genes and the risk of developing familial prostate carcinoma. MATERIALS AND METHODS: In this study, 34 cases with prostate carcinoma whose first-degree relatives had prostate carcinoma and 30 healthy age-matched male controls were enrolled. The genotypes of ESR1 and COMT genes were analyzed employing polymerase chain reaction-restriction fragment length polymorphism method. 34 cases with prostate carcinoma, whose first degree relatives had prostate carcinoma and 14 age-matched male controls were enrolled to analyze the genotype of these two genes. RESULTS: Among control patients, the ESR1 PvuII genotypes of C/C, C/T and T/T were observed in 37%, 26% and 37%, respectively, whereas the C/C, C/T and T/T genotypes were observed in 18%, 41% and 41% of case patients, respectively. Among controls, the ESR1 PvuII allele frequencies of C and T were equally observed, whereas the C and T allele frequencies were observed in 38% and 62% of patients, respectively. Among ESR1 PvuII genotypes there were not any significant difference in terms of genotype (P = 0.199) and allele (P = 0.181) frequencies. Among controls, the ESR1 XbaI genotypes of G/G, G/A and A/A were observed in 33%, 37% and 33%, respectively, whereas the G/G, G/A and A/A genotypes were observed in 12%, 47% and 41% of patients, respectively. Among controls, the ESR1 XbaI allele frequencies of A and G were observed equally, respectively, whereas the A and G frequencies were observed in 65% and 35% of patients, respectively. Among ESR1 Χ baI, there was not any significant difference in terms of genotype (P = 0.111) and allele (P = 0

  11. Evaluation of antioxidant properties of monoaromatic derivatives of pulvinic acids.

    PubMed

    Habrant, Damien; Poigny, Stéphane; Ségur-Derai, Muriel; Brunel, Yves; Heurtaux, Benoît; Le Gall, Thierry; Strehle, Axelle; Saladin, Régis; Meunier, Stéphane; Mioskowski, Charles; Wagner, Alain

    2009-04-23

    The natural mushroom pigment Norbadione A and three other pulvinic acids were shown by our group to display very efficient antioxidant properties by comparison with a collection of potent molecules including catechols, flavonoids, stilbenes, or coumarins. Despite numerous publications on robust and straightforward synthetic access to pulvinic acids by us and others, no report has been made to unravel the structure-activity relationships that govern the striking antioxidant activity. Herein is presented the synthesis of 18 diverse pulvinic acid derivatives and the study of their radical scavenging capacities by four different assays. The influence of each of the two phenyl rings, of their substituents and of the lateral chain on the antioxidant properties, was explored to reveal a simplified structure of excellent activity. These results, along with the absence of cytotoxicity, make the synthesized compounds interesting to evaluate for several biological activities and especially for anti-inflammatory effects and skin protection against UV induced oxidative stress.

  12. Radiometric assay for phenylethanolamine N-methyltransferase and catechol O-methyltransferase in a single tissue sample: application to rat hypothalamic nuclei, pineal gland, and heart

    SciTech Connect

    Culman, J.; Torda, T.; Weise, V.K.

    1987-08-01

    A simple and highly sensitive method for simultaneous assay of phenylethanolamine N-methyltransferase (PNMT) and catechol O-methyltransferase (COMT) is described. These enzymes are determined in a single tissue homogenate using S-(methyl-/sup 3/H) adenosyl-L-methionine as methyl donor and sequentially incubating with the substrates phenylethanolamine and epinephrine. The radioactive products of the enzymatic reactions, N-methylphenylethanolamine and metanephrine, are extracted and then separated by thin-layer chromatography. The identity of the reaction products has been established chromatographically and the conditions for both enzymatic reactions in the assay procedure have been defined. Measurement of PNMT activity in the rat pineal gland or in minute fragments of other tissues (e.g., brain nuclei) has not been possible using previously described methods. Activities of PNMT and COMT in the rat pineal gland, various hypothalamic nuclei, and the auricular and ventricular myocardia are herein reported.

  13. The Role of the Catechol-o-methyltransferase (COMT) Gene Val158Met in Aggressive Behavior, A Review of Genetic Studies

    PubMed Central

    Qayyum, Arqam; Zai, Clement C.; Hirata, Yuko; Tiwari, Arun K.; Cheema, Sheraz; Nowrouzi, Behdin; Beitchman, Joseph H.; Kennedy, James L.

    2015-01-01

    Aggressive behaviors have become a major public health problem, and early-onset aggression can lead to outcomes such as substance abuse, antisocial personality disorder among other issues. In recent years, there has been an increase in research in the molecular and genetic underpinnings of aggressive behavior, and one of the candidate genes codes for the catechol-O-methyltransferase (COMT). COMT is involved in catabolizing catecholamines such as dopamine. These neurotransmitters appear to be involved in regulating mood which can contribute to aggression. The most common gene variant studied in the COMT gene is the Valine (Val) to Methionine (Met) substitution at codon 158. We will be reviewing the current literature on this gene variant in aggressive behavior. PMID:26630958

  14. Oxidant activity of tris(2,4,6-trichloro-3,5-dinitrophenyl)methyl radical with catechol and pyrogallol. Mechanistic considerations.

    PubMed

    Carreras, Anna; Esparbé, Isaac; Brillas, Enric; Rius, Jordi; Torres, Josep Lluís; Julià, Luis

    2009-03-20

    The reducing activity of simple polyphenols (PhOH), catechol and pyrogallol, is tested in different solvents in front of tris(2,4,6-trichloro-3,5-dinitrophenyl)methyl (HNTTM) radical, a stable organic free radical of the TTM series. HNTTM radical is very active in electron-transfer reactions to give a very stable anion. The standard potential for the reduction of HNTTM radical by cyclic voltammetry in different solvents is E(o) = 0.60 +/- 5 V vs SCE. In hydroxylic solvents, the electron transfer is a very rapid process and the electron-donating species is the ionized PhO(-), whereas in nonpolar solvents, it is suggested that the electron transfer is facilitated by the formation of an intermediate complex between HNTTM and PhOH.

  15. 4-Nitrocatecholato iron(III) complexes of 2-aminomethyl pyridine-based bis(phenol) amine as structural models for catechol-bound 3,4-PCD

    NASA Astrophysics Data System (ADS)

    Safaei, Elham; Heidari, Sima; Wojtczak, Andrzej; Cotič, Patricia; Kozakiewicz, Anna

    2016-02-01

    Two nitrocatecholato(HNC) iron(III) complexes, [FeLAMPX(H-NC)]. NEt3, of the tetradendate ligand (2-aminomethylpyridine)bis(2-pyridylmethyl)amine (H2LAMPX) were synthesized and structurally characterized. These structural models for catechol-bound 3,4-PCD were characterized by IR, UV-vis, elemental analysis and magnetic measurements. X-ray crystallography studies revealed that in both complexes the iron(III) centers are distorted octahedral and coordinated by two phenolate oxygen's, two amine nitrogen's of the ligand and mono anionic nitrocatecholate group (HNC). The variable-temperature magnetic susceptibility studies revealed paramagnetic properties of the reported complexes. The effective magnetic moments for the complexes lie between 5.3 and 5.4 BM correspond to the reported values for high spin Fe(III) center. The ligand-centered oxidation and metal-centered reduction of complexes was studies using cyclic voltammetry (CV) technique.

  16. Detoxifying polyhalogenated catechols through a copper-chelating agent by forming stable and redox-inactive hydrogen-bonded complexes with an unusual perpendicular structure.

    PubMed

    Li, Yan; Huang, Chun-Hua; Liu, Yu-Xiang; Mao, Li; Zhu, Ben-Zhan

    2014-09-26

    The use of selective metal chelating agents with preference for binding of a specific metal ion to investigate its biological role is becoming increasingly common. We found recently that a well-known copper-specific chelator 2,9-dimethyl-1,10-phenanthroline (2,9-Me2OP) could completely inhibit the synergistic toxicity induced by tetrachlorocatechol (TCC) and sodium azide (NaN3). However, its underlying molecular mechanism is still not clear. Here, we show that the protection by 2,9-Me2OP is not due to its classic copper-chelating property, but rather due to formation of a multiple hydrogen-bonded complex between 2,9-Me2OP and TCC, featuring an unusual perpendicular arrangement of the two binding partners. The two methyl groups at the 2,9 positions in 2,9-Me2OP were found to be critical to stabilize the 2,9-Me2OP/TCC complex due to steric hindrance, and therefore completely prevents the generation of the reactive and toxic semiquinone radicals by TCC/NaN3. This represents the first report showing that an unexpected new protective mode of action for the copper "specific" chelating agent 2,9-Me2OP by using its steric hindrance effect of the two CH3 groups not only to chelate copper, but also to "chelate" a catechol through multiple H-bonding. These findings may have broad biological implications for future research of this widely used copper-chelating agent and the ubiquitous catecholic compounds.

  17. Dielectric and electrophoretic properties of wax dispersions in the presence of pour depressants

    SciTech Connect

    Agaev, S.G.; Taranova, L.V.

    1987-05-01

    It appeared to be of interest to evaluate the depressant efficiency of additives on the basis of results obtained in studying electrophoretic and dielectric properties of wax-containing systems when these additives are present. The electrical properties of dispersion of a petroleum paraffin wax (mp 56/sup 0/C) in n-heptane were investigated in the presence of the commercial pour depressants PMD D (specification TU 01-270-68) (a polymethyacrylate) and AzNII (GOST (All-Union State Standard) 8443-57) (condensation product from chlorinated wax and naphthalene), and two ester-type additives synthesized in the laboratory: TyumII 79, which is bis(diacylpentarythritol 4-nitrophthalate) and TyumII 222, which is bis(diacylpentarythritol succinate). The pour depressants TyumII 79 and TyumII 222 are products obtained by condensation of C/sub 21/-C/sub 26/ synthetic fatty acids, pentaerythritol, and a dicarboxylic acid (4-nitrophthalic acid or succinic acid), with component ratio 2.1:1:1 and 2.1:1:0.55, respectively.

  18. Fluorinated Boronic Acid-Appended Bipyridinium Salts for Diol Recognition and Discrimination via (19)F NMR Barcodes.

    PubMed

    Axthelm, Jörg; Görls, Helmar; Schubert, Ulrich S; Schiller, Alexander

    2015-12-16

    Fluorinated boronic acid-appended benzyl bipyridinium salts, derived from 4,4'-, 3,4'-, and 3,3'-bipyridines, were synthesized and used to detect and differentiate diol-containing analytes at physiological conditions via (19)F NMR spectroscopy. An array of three water-soluble boronic acid receptors in combination with (19)F NMR spectroscopy discriminates nine diol-containing bioanalytes--catechol, dopamine, fructose, glucose, glucose-1-phosphate, glucose-6-phosphate, galactose, lactose, and sucrose--at low mM concentrations. Characteristic (19)F NMR fingerprints are interpreted as two-dimensional barcodes without the need of multivariate analysis techniques.

  19. Studies in vitro on the involvement of O-sulphate esters in the formation of O-methylated 3,4-dihydroxybenzoic acid by rat liver.

    PubMed

    Pennings, E J; Van Kempen, G M

    1981-03-01

    The involvement of O-sulphate esters in the directed O-methylation was investigated in vitro with a dialysed "high-speed' supernatant from rat liver as the enzyme preparation and the catechol compound 3,4-dihydroxybenzoic acid as the substrate. The enzyme reactions involved were studied separately with the O-methylated and O-sulphated derivatives. The rate of hydrolysis by arylsulphatase was 14.5 nmol/min per mg of protein for 3-methoxy-4-sulphonyloxybenzoic acid and 10.1 nmol/min per mg of protein for 4-methoxy-3-sulphonyloxybenzoic acid. The sulphotransferase activity towards the guaiacols 4-hydroxy-3-methoxybenzoic acid and 3-hydroxy-4-methoxybenzoic acid was 570pmol of 4-O-sulphated and 350pmol of 3-O-sulphated product formed/min per mg of protein. The 3-O- and 4-O-sulphate esters of 3,4-dihydroxybenzoic acid could not serve as substrates for the catechol O-methyltransferase reaction. When either ester was incubated in the presence of S-adenosyl-L-methionine, but without the arylsulphatase inhibitor KH2PO4, 3,4-dihydroxybenzoic acid was formed, which was subsequently O-methylated in a meta/para ratio of 4.6. It is concluded that O-methylation can precede O-sulphation but that O-sulphation prevents further metabolism by O-methylation. Also O-sulphate esters do not have a directing effect on O-methylation. From the study of the simultaneous action of sulphotransferase and catechol O-methyltransferase on 3,4-dihydroxybenzoic acid we conclude that O-sulphation and O-methylation proceed independently of each other under the assay conditions used, both directed preferentially to the 3-hydroxy group.

  20. Inhibitive detection of benzoic acid using a novel phenols biosensor based on polyaniline-polyacrylonitrile composite matrix.

    PubMed

    Shan, Dan; Shi, Qiaofang; Zhu, Daobin; Xue, Huaiguo

    2007-07-31

    A novel sensitive and stable phenols amperometric biosensor, based on polyaniline-polyacrylonitrile composite matrix, was applied for determination of benzoic acid. The electrochemical biosensor functioning was based on the inhibition effect of benzoic acid on the biocatalytic activity of the polyphenol oxidase (PPO) to its substrate (catechol) in 0.1M phosphate buffer solution (pH 6.5). A potential value of -50 mV versus SCE, and a constant catechol concentration of 20 microM were selective to carry out the amperometric inhibition measurement. The kinetic parameters Michaelis-Menten constant (K(M)(app)) and maximum current (I(max)) in the absence and in the presence of benzoic acid were also evaluated and the possible inhibition mechanism was deduced. The inhibiting action of benzoic acid on the polyphenol oxidase electrode was reversible and of the typical competitive type, with an apparent inhibition constant of 38 microM. This proposed biosensor detected levels of benzoic acid as low as 2x10(-7)M in solution. In addition, the effects of temperature, pH value of solution on the inhibition and the interferences were investigated and discussed herein. Inhibition studies revealed that the proposed electrochemical biosensor was applicable for monitoring benzoic acid in real sample such as milk, yoghurt, sprite and cola. PMID:19071830

  1. Electroanalytical and Spectroscopic Studies of Poly(2,2'-bithiophene)-Modified Platinum Electrode to Detect Catechol in the Presence of Ascorbic Acid

    ERIC Educational Resources Information Center

    Lunsford, Suzanne K.; Speelman, Nicole; Stinson, Jelynn; Yeary, Amber; Choi, Hyeok; Widera, Justyna; Dionysiou, Dionysios D.

    2008-01-01

    This article describes an undergraduate laboratory for an instrumental analysis course that integrates electroanalytical chemistry and infrared spectroscopy. Modified electrode surfaces are prepared by constant potentiometric electrolysis over the potential range of 1.5-1.8 V and analyzed by cyclic voltammetry and infrared spectroscopy. The…

  2. Development of Blood-Brain Barrier Permeable Nitrocatechol-Based Catechol O-Methyltransferase Inhibitors with Reduced Potential for Hepatotoxicity.

    PubMed

    Silva, Tiago; Mohamed, Tarek; Shakeri, Arash; Rao, Praveen P N; Martínez-González, Loreto; Pérez, Daniel I; Martínez, Ana; Valente, Maria João; Garrido, Jorge; Uriarte, Eugenio; Serrão, Paula; Soares-da-Silva, Patrício; Remião, Fernando; Borges, Fernanda

    2016-08-25

    Recent efforts have been focused on the development of centrally active COMT inhibitors, which can be valuable assets for neurological disorders such as Parkinson's disease, due to the severe hepatotoxicity risk associated with tolcapone. New nitrocatechol COMT inhibitors based on naturally occurring caffeic acid and caffeic acid phenethyl ester were developed. All nitrocatechol derivatives displayed potent inhibition of peripheral and cerebral COMT within the nanomolar range. Druglike derivatives 13, 15, and 16 were predicted to cross the blood-brain barrier in vitro and were significantly less toxic than tolcapone and entacapone when incubated at 50 μM with rat primary hepatocytes. Moreover, their unique acidity and electrochemical properties decreased the chances of formation of reactive quinone-imines and, as such, the potential for hepatotoxicity. The binding mode of 16 confirmed that the major interactions with COMT were established via the nitrocatechol ring, allowing derivatization of the side chain for future lead optimization efforts. PMID:27463695

  3. Development of Blood-Brain Barrier Permeable Nitrocatechol-Based Catechol O-Methyltransferase Inhibitors with Reduced Potential for Hepatotoxicity.

    PubMed

    Silva, Tiago; Mohamed, Tarek; Shakeri, Arash; Rao, Praveen P N; Martínez-González, Loreto; Pérez, Daniel I; Martínez, Ana; Valente, Maria João; Garrido, Jorge; Uriarte, Eugenio; Serrão, Paula; Soares-da-Silva, Patrício; Remião, Fernando; Borges, Fernanda

    2016-08-25

    Recent efforts have been focused on the development of centrally active COMT inhibitors, which can be valuable assets for neurological disorders such as Parkinson's disease, due to the severe hepatotoxicity risk associated with tolcapone. New nitrocatechol COMT inhibitors based on naturally occurring caffeic acid and caffeic acid phenethyl ester were developed. All nitrocatechol derivatives displayed potent inhibition of peripheral and cerebral COMT within the nanomolar range. Druglike derivatives 13, 15, and 16 were predicted to cross the blood-brain barrier in vitro and were significantly less toxic than tolcapone and entacapone when incubated at 50 μM with rat primary hepatocytes. Moreover, their unique acidity and electrochemical properties decreased the chances of formation of reactive quinone-imines and, as such, the potential for hepatotoxicity. The binding mode of 16 confirmed that the major interactions with COMT were established via the nitrocatechol ring, allowing derivatization of the side chain for future lead optimization efforts.

  4. Ru3(CO)12-catalyzed reactions of catechols with alkynes: an atom-economic process for the synthesis of 2,2-disubstituted 1,3-benzodioxoles from the double addition of the O-H bond across a triple bond.

    PubMed

    Li, Ming; Hua, Ruimao

    2008-11-01

    Ru3(CO)12 has been found to be the efficient catalyst for the addition reactions of catechols with both terminal and internal alkynes to selectively afford 2,2-disubstituted 1,3-benzodioxoles in good to high yields. The formation of 2,2-substituted 1,3-benzodioxoles results from the tandem addition of two O-H bonds of catechols to alkyne's triple bond.

  5. New lipophilic piceatannol derivatives exhibiting antioxidant activity prepared by aromatic hydroxylation with 2-iodoxybenzoic acid (IBX).

    PubMed

    Bernini, Roberta; Barontini, Maurizio; Spatafora, Carmela

    2009-01-01

    Piceatannol (E-3,5,3',4'-tetrahydroxystilbene) is a phytoalexin synthesized in grapes in response to stress conditions. It exhibits strong antioxidant and antileukaemic activities due to the presence of the catechol moiety. To modify some physical properties like solubility, and miscibility in non-aqueous media some new previously unreported piceatannol derivatives having lipophilic chains on the A-ring were prepared in good yields by a simple and efficient procedure. The key step was a chemo- and regioselective aromatic hydroxylation with 2-iodoxybenzoic acid (IBX). The new compounds showed antioxidant activity and seemed promising for possible applications as multifunctional emulsifiers in food, cosmetic and pharmaceutical fields.

  6. Solid-Phase Spectrophotometric Analysis of 1-Naphthol Using Silica Functionalized with m-Diazophenylarsonic Acid

    NASA Astrophysics Data System (ADS)

    Zaitseva, Nataliya; Alekseev, Sergei; Zaitsev, Vladimir; Raks, Viktoria

    2016-03-01

    The m-aminophenylarsonic acid (m-APAA) was immobilized onto the silica gel surface with covalently grafted quaternary ammonium groups via ion exchange. The diazotization of ion-bonded m-APAA resulted in a new solid-phase spectrophotometric reagent for detection of 1-naphtol in environmental water samples. The procedure of solid-phase spectrophotometric analysis is characterized by 20 μg L-1 limit of detection (LOD) of 1-naphtol, up to 2000 concentration factor, and insensitivity to the presence of natural water components as well as to 30-fold excess of phenol, resorcinol, and catechol.

  7. Tyrosinase Models. Synthesis, Structure, Catechol Oxidase Activity, and Phenol Monooxygenase Activity of a Dinuclear Copper Complex Derived from a Triamino Pentabenzimidazole Ligand.

    PubMed

    Monzani, Enrico; Quinti, Luisa; Perotti, Angelo; Casella, Luigi; Gullotti, Michele; Randaccio, Lucio; Geremia, Silvano; Nardin, Giorgio; Faleschini, Paolo; Tabbì, Giovanni

    1998-02-01

    The dicopper(II) complex with the ligand N,N,N',N',N"-pentakis[(1-methyl-2-benzimidazolyl)methyl]dipropylenetriamine (LB5) has been synthesized and structurally characterized. The small size and the quality of the single crystal required that data be collected using synchrotron radiation at 276 K. [Cu(2)(LB5)(H(2)O)(2)][ClO(4)](4): platelet shaped, P&onemacr;, a = 11.028 Å, b = 17.915 Å, c = 20.745 Å, alpha = 107.44 degrees, beta = 101.56 degrees, gamma = 104.89 degrees, V = 3603.7 Å(3), Z = 2; number of unique data, I >/= 2sigma(I) = 3447; number of refined parameters = 428; R = 0.12. The ligand binds the two coppers nonsymmetrically; Cu1 is coordinated through five N donors and Cu2 through the remaining three N donors, while two water molecules complete the coordination sphere. Cu1 has distorted TBP geometry, while Cu2 has distorted SP geometry. Voltammetric experiments show quasireversible reductions at the two copper centers, with redox potential higher for the CuN(3) center (0.40 V) and lower for the CuN(5) center (0.17 V). The complex binds azide in the terminal mode at the CuN(3) center with affinity lower than that exhibited by related dinuclear polyaminobenzimidazole complexes where this ligand is bound in the bridging mode. The catechol oxidase activity of [Cu(2)(LB5)](4+) has been examined in comparison with that exhibited by [Cu(2)(L-55)](4+) (L-55 = alpha,alpha'-bis{bis[(1-methyl-2-benzimidazolyl)methyl]amino}-m-xylene) and [Cu(2)(L-66)](4+) (L-66 = alpha,alpha'-bis{bis[2-(1-methyl-2-benzimidazolyl)ethyl]amino}-m-xylene) by studying the catalytic oxidation of 3,5-di-tert-butylcatechol in methanol/aqueous buffer pH 5.1. Kinetic experiments show that [Cu(2)(L-55)](4+) is the most efficient catalyst (rate constant 140 M(-1) s(-1)), followed by [Cu(2)(LB5)](4+) (60 M(-1) s(-1)), in this oxidation, while [Cu(2)(L-66)](4+) undergoes an extremely fast stoichiometric phase followed by a slow and substrate-concentration-independent catalytic phase. The

  8. Iron(III) oxidized nucleophilic coupling of catechol with o-tolidine/p-toluidine followed by 1,10-phenanthroline as new and sensitivity improved spectrophotometric methods for iron present in chemicals, pharmaceutical, edible green leaves, nuts and lake water samples

    NASA Astrophysics Data System (ADS)

    Shyla, B.; Bhaskar, C. Vijaya; Nagendrappa, G.

    2012-02-01

    A nucleophile formed from iron(III) oxidized catechol in 0.1 M hydrochloric acid couple with o-tolidine, system 1/p-toluidine, system 2 to produce dye product, λ max 520 nm. The system 1/2 obeys Beer's law in the range 0.08-8.0 μg ml -1 with molar absorptivity, Sandell sensitivity and regression coefficient values, 4.225 × 10 3/3.140 × 10 3 l mol -1 cm -1, 0.0132/0.0178 μg cm -2 and 0.9987/0.9981. Iron(II) formed from iron(III) in system 1/2 reacts with 1,10-phenanthroline, λ max 510 nm, will constitute sensitivity improved iron determinations with values 0.08-1.6 μg ml -1, 2.4136 × 10 4/2.2511 × 10 4 l mol -1 cm -1, 0.0023/0.0025 μg cm -2 and 0.9980/0.9997 corresponding to range, molar absorptivity, Sandell sensitivity and regression coefficient. The results of the systems for iron present in chemicals, pharmaceutical, edible green leaves, nuts and lake water samples are satisfactory since they are comparable with the results of iron determined separately from 1,10-phenanthroline method.

  9. Metabolic Engineering of a Novel Muconic Acid Biosynthesis Pathway via 4-Hydroxybenzoic Acid in Escherichia coli

    PubMed Central

    Sengupta, Sudeshna; Goonewardena, Lakshani; Juturu, Veeresh

    2015-01-01

    cis,cis-Muconic acid (MA) is a commercially important raw material used in pharmaceuticals, functional resins, and agrochemicals. MA is also a potential platform chemical for the production of adipic acid (AA), terephthalic acid, caprolactam, and 1,6-hexanediol. A strain of Escherichia coli K-12, BW25113, was genetically modified, and a novel nonnative metabolic pathway was introduced for the synthesis of MA from glucose. The proposed pathway converted chorismate from the aromatic amino acid pathway to MA via 4-hydroxybenzoic acid (PHB). Three nonnative genes, pobA, aroY, and catA, coding for 4-hydroxybenzoate hydrolyase, protocatechuate decarboxylase, and catechol 1,2-dioxygenase, respectively, were functionally expressed in E. coli to establish the MA biosynthetic pathway. E. coli native genes ubiC, aroFFBR, aroE, and aroL were overexpressed and the genes ptsH, ptsI, crr, and pykF were deleted from the E. coli genome in order to increase the precursors of the proposed MA pathway. The final engineered E. coli strain produced nearly 170 mg/liter of MA from simple carbon sources in shake flask experiments. The proposed pathway was proved to be functionally active, and the strategy can be used for future metabolic engineering efforts for production of MA from renewable sugars. PMID:26362984

  10. Metabolic engineering of a novel muconic acid biosynthesis pathway via 4-hydroxybenzoic acid in Escherichia coli.

    PubMed

    Sengupta, Sudeshna; Jonnalagadda, Sudhakar; Goonewardena, Lakshani; Juturu, Veeresh

    2015-12-01

    cis,cis-Muconic acid (MA) is a commercially important raw material used in pharmaceuticals, functional resins, and agrochemicals. MA is also a potential platform chemical for the production of adipic acid (AA), terephthalic acid, caprolactam, and 1,6-hexanediol. A strain of Escherichia coli K-12, BW25113, was genetically modified, and a novel nonnative metabolic pathway was introduced for the synthesis of MA from glucose. The proposed pathway converted chorismate from the aromatic amino acid pathway to MA via 4-hydroxybenzoic acid (PHB). Three nonnative genes, pobA, aroY, and catA, coding for 4-hydroxybenzoate hydrolyase, protocatechuate decarboxylase, and catechol 1,2-dioxygenase, respectively, were functionally expressed in E. coli to establish the MA biosynthetic pathway. E. coli native genes ubiC, aroF(FBR), aroE, and aroL were overexpressed and the genes ptsH, ptsI, crr, and pykF were deleted from the E. coli genome in order to increase the precursors of the proposed MA pathway. The final engineered E. coli strain produced nearly 170 mg/liter of MA from simple carbon sources in shake flask experiments. The proposed pathway was proved to be functionally active, and the strategy can be used for future metabolic engineering efforts for production of MA from renewable sugars. PMID:26362984

  11. Model reactions for insect cuticle sclerotization: cross-linking of recombinant cuticular proteins upon their laccase-catalyzed oxidative conjugation with catechols.

    PubMed

    Suderman, Richard J; Dittmer, Neal T; Kanost, Michael R; Kramer, Karl J

    2006-04-01

    . These results support the hypothesis that during sclerotization, insect cuticular proteins are oxidatively conjugated with catechols, a posttranslational process termed catecholation, and then become cross-linked, forming oligomers and subsequently polymers.

  12. The Cu-MOF-199/single-walled carbon nanotubes modified electrode for simultaneous determination of hydroquinone and catechol with extended linear ranges and lower detection limits.

    PubMed

    Zhou, Jian; Li, Xi; Yang, Linlin; Yan, Songlin; Wang, Mengmeng; Cheng, Dan; Chen, Qi; Dong, Yulin; Liu, Peng; Cai, Weiquan; Zhang, Chaocan

    2015-10-29

    A novel electrochemical sensor based on Cu-MOF-199 [Cu-MOF-199 = Cu3(BTC)2 (BTC = 1,3,5-benzenetricarboxylicacid)] and SWCNTs (single-walled carbon nanotubes) was fabricated for the simultaneous determination of hydroquinone (HQ) and catechol (CT). The modification procedure was carried out through casting SWCNTs on the bare glassy carbon electrode (GCE) and followed by the electrodeposition of Cu-MOF-199 on the SWCNTs modified electrode. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) were performed to characterize the electrochemical performance and surface characteristics of the as-prepared sensor. The composite electrode exhibited an excellent electrocatalytic activity with increased electrochemical signals towards the oxidation of HQ and CT, owing to the synergistic effect of SWCNTs and Cu-MOF-199. Under the optimized condition, the linear response range were from 0.1 to 1453 μmol L(-1) (RHQ = 0.9999) for HQ and 0.1-1150 μmol L(-1) (RCT = 0.9990) for CT. The detection limits for HQ and CT were as low as 0.08 and 0.1 μmol L(-1), respectively. Moreover, the modified electrode presented the good reproducibility and the excellent anti-interference performance. The analytical performance of the developed sensor for the simultaneous detection of HQ and CT had been evaluated in practical samples with satisfying results.

  13. Novel, unifying mechanism for mescaline in the central nervous system: electrochemistry, catechol redox metabolite, receptor, cell signaling and structure activity relationships.

    PubMed

    Kovacic, Peter; Somanathan, Ratnasamy

    2009-01-01

    A unifying mechanism for abused drugs has been proposed previously from the standpoint of electron transfer. Mescaline can be accommodated within the theoretical framework based on redox cycling by the catechol metabolite with its quinone counterpart. Electron transfer may play a role in electrical effects involving the nervous system in the brain. This approach is in accord with structure activity relationships involving mescaline, abused drugs, catecholamines, and etoposide. Inefficient demethylation is in keeping with the various drug properties, such as requirement for high dosage and slow acting. There is a discussion of receptor binding, electrical effects, cell signaling and other modes of action. Mescaline is a nonselective, seretonin receptor agonist. 5-HTP receptors are involved in the stimulus properties. Research addresses the aspect of stereochemical requirements. Receptor binding may involve the proposed quinone metabolite and/or the amino sidechain via protonation. Electroencephalographic studies were performed on the effects of mescaline on men. Spikes are elicited by stimulation of a cortical area. The potentials likely originate in nonsynaptic dendritic membranes. Receptor-mediated signaling pathways were examined which affect mescaline behavior. The hallucinogen belongs to the class of 2AR agonists which regulate pathways in cortical neurons. The research identifies neural and signaling mechanisms responsible for the biological effects. Recently, another hallucinogen, psilocybin, has been included within the unifying mechanistic framework. This mushroom constituent is hydrolyzed to the phenol psilocin, also active, which is subsequently oxidized to an ET o-quinone or iminoquinone.

  14. Determination of Methylated CpG Sites in the Promoter Region of Catechol-O-Methyltransferase (COMT) and their Involvement in the Etiology of Tobacco Smoking.

    PubMed

    Xu, Qing; Ma, Jennie Z; Payne, Thomas J; Li, Ming D

    2010-01-01

    We previously reported that catechol-O-methyltransferase (COMT) is significantly associated with nicotine dependence (ND) in humans. In this study, we examined whether there exists any difference in the extent of methylation of CpG dinucleotides in the promoter region of COMT in smokers and non-smokers by analyzing the methylation status of cytosines at 33 CpG sites through direct sequencing of bisulfite-treated DNA (N = 50 per group). The cytosine was methylated at 13 of 33 CpG sites, and two of these sites showed significant differences between smokers and matched non-smoker controls. Specifically, in the -193 CpG site, the degree of methylation was 19.1% in smokers and 13.2% in non-smokers (P < 0.01). This finding was confirmed by methylation-specific PCR using an additional 100 smoker and 100 non-smoker control samples, which showed the degree of methylation to be 22.2% in smokers and 18.3% in non-smokers (P < 0.01). For the -39 CpG site, the degree of methylation was 9.2% in smokers, whereas no methylation was found in non-smoker controls. Together, our findings provide the first molecular explanation at the epigenetic level for the association of ND with methylation of the COMT promoter, implying that methylation plays a role in smoking dependence. PMID:21423427

  15. Catechol-O-methyltransferase inhibition alters pain and anxiety-related volitional behaviors through activation of β-adrenergic receptors in the rat.

    PubMed

    Kline, R H; Exposto, F G; O'Buckley, S C; Westlund, K N; Nackley, A G

    2015-04-01

    Reduced catechol-O-methyltransferase (COMT) activity resulting from genetic variation or pharmacological depletion results in enhanced pain perception in humans and nociceptive behaviors in animals. Using phasic mechanical and thermal reflex tests (e.g. von Frey, Hargreaves), recent studies show that acute COMT-dependent pain in rats is mediated by β-adrenergic receptors (βARs). In order to more closely mimic the characteristics of human chronic pain conditions associated with prolonged reductions in COMT, the present study sought to determine volitional pain-related and anxiety-like behavioral responses following sustained as well as acute COMT inhibition using an operant 10-45°C thermal place preference task and a light/dark preference test. In addition, we sought to evaluate the effects of sustained COMT inhibition on generalized body pain by measuring tactile sensory thresholds of the abdominal region. Results demonstrated that acute and sustained administration of the COMT inhibitor OR486 increased pain behavior in response to thermal heat. Further, sustained administration of OR486 increased anxiety behavior in response to bright light, as well as abdominal mechanosensation. Finally, all pain-related behaviors were blocked by the non-selective βAR antagonist propranolol. Collectively, these findings provide the first evidence that stimulation of βARs following acute or chronic COMT inhibition drives cognitive-affective behaviors associated with heightened pain that affects multiple body sites.

  16. Catechol-O-methlytransferase inhibition alters pain and anxiety-related volitional behaviors through activation of β-adrenergic receptors in the rat

    PubMed Central

    Kline, R. H.; Exposto, F. G.; O’Buckley, S. C.; Westlund, K. N.; Nackley, A. G.

    2015-01-01

    Reduced catechol-O-methyltransferase (COMT) activity resulting from genetic variation or pharmacological depletion results in enhanced pain perception in humans and nociceptive behaviors in animals. Using phasic mechanical and thermal reflex tests (e.g. von Frey, Hargreaves), recent studies show that acute COMT-dependent pain in rats is mediated by β-adrenergic receptors (βARs). In order to more closely mimic the characteristics of human chronic pain conditions associated with prolonged reductions in COMT, the present study sought to determine volitional pain-related and anxiety-like behavioral responses following sustained as well as acute COMT inhibition using an operant 10–45°C thermal place preference task and a light/dark preference test. In addition, we sought to evaluate the effects of sustained COMT inhibition on generalized body pain by measuring tactile sensory thresholds of the abdominal region. Results demonstrated that acute and sustained administration of the COMT inhibitor OR486 increased pain behavior in response to thermal heat. Further, sustained administration of OR486 increased anxiety behavior in response to bright light, as well as abdominal mechanosensation. Finally, all pain-related behaviors were blocked by the non-selective βAR antagonist propranolol. Collectively, these findings provide the first evidence that stimulation of ARs following acute or chronic COMT inhibition drives cognitive-affective behaviors associated with heightened pain that affects multiple body sites. PMID:25659347

  17. Opicapone: a short lived and very long acting novel catechol-O-methyltransferase inhibitor following multiple dose administration in healthy subjects

    PubMed Central

    Rocha, José Francisco; Almeida, Luis; Falcão, Amílcar; Palma, P Nuno; Loureiro, Ana I; Pinto, Roberto; Bonifácio, Maria João; Wright, Lyndon C; Nunes, Teresa; Soares-da-Silva, Patrício

    2013-01-01

    Aims The aim of this study was to assess the tolerability, pharmacokinetics and inhibitory effect on erythrocyte soluble catechol-O-methyltransferase (S-COMT) activity following repeated doses of opicapone. Methods This randomized, placebo-controlled, double-blind study enrolled healthy male subjects who received either once daily placebo or opicapone 5, 10, 20 or 30 mg for 8 days. Results Opicapone was well tolerated. Its systemic exposure increased in an approximately dose-proportional manner with an apparent terminal half-life of 1.0 to 1.4 h. Sulphation was the main metabolic pathway. Opicapone metabolites recovered in urine accounted for less than 3% of the amount of opicapone administered suggesting that bile is likely the main route of excretion. Maximum S-COMT inhibition (Emax) ranged from 69.9% to 98.0% following the last dose of opicapone. The opicapone-induced S-COMT inhibition showed a half-life in excess of 100 h, which was dose-independent and much longer than plasma drug exposure. Such a half-life translates into a putative underlying rate constant that is comparable with the estimated dissociation rate constant of the COMT–opicapone complex. Conclusion Despite its short elimination half-life, opicapone markedly and sustainably inhibited erythrocyte S-COMT activity making it suitable for a once daily regimen. PMID:23336248

  18. Association of catechol-O-methyltransferase Val(108/158) Met genetic polymorphism with schizophrenia, P50 sensory gating, and negative symptoms in a Chinese population.

    PubMed

    Mao, Qiao; Tan, Yun-Long; Luo, Xing-Guang; Tian, Li; Wang, Zhi-Ren; Tan, Shu-Ping; Chen, Song; Yang, Gui-Gang; An, Hui-Mei; Yang, Fu-De; Zhang, Xiang-Yang

    2016-08-30

    Catechol-O-methyltransferase (COMT), an enzyme involved in the degradation and inactivation of the neurotransmitter dopamine, is associated with the sensory gating phenomenon, protecting the cerebral cortex from information overload. The COMT Val(108/158)Met polymorphism is essential for prefrontal cortex processing capacity and efficiency. The current study was designed to investigate the role of COMT Val(108/158)Met polymorphism in development, sensory gating deficit, and symptoms of schizophrenia in Han Chinese population. P50 gating was determined in 139 schizophrenic patients and 165 healthy controls. Positive and Negative Syndrome Scale (PANSS) was used to assess the clinical symptomatology in 370 schizophrenic subjects. COMT Val(108/158)Met polymorphism was genotyped by PCR-restriction fragment length polymorphism (PCR-RFLP). No significant differences in COMT allele and genotype distributions were observed between schizophrenic patients and control groups. Although P50 deficits were present in patients, there was no evidence for an association between COMT Val(108/158)Met polymorphism and the P50 biomarker. Moreover, PANSS negative subscore was significantly higher in Val allele carriers than in Met/Met individuals. The present findings suggest that COMT Val(108/158)Met polymorphism may not contribute to the risk of schizophrenia and to the P50 deficits, but may contribute to the negative symptoms of schizophrenia among Han Chinese. PMID:27315458

  19. Facile one-pot synthesis and application of nitrogen and sulfur-doped activated graphene in simultaneous electrochemical determination of hydroquinone and catechol.

    PubMed

    Xiao, Lili; Yin, Jiao; Li, Yingchun; Yuan, Qunhui; Shen, Hangjia; Hu, Guangzhi; Gan, Wei

    2016-10-01

    Nitrogen (N) and sulfur (S) co-doped activated graphene (N,S-AGR) was prepared by the one-pot pyrolysis of a mixture of graphene oxide (GO), thiourea, and potassium hydroxide (KOH), where thiourea acts as the source of N and S dopants and KOH is the activator for porosity. N,S-AGR with a dopant abundance of 2.8 at% N and 2.3 at% S was then used as a high-activity electrocatalyst in the fabrication of an electrochemical sensor for simultaneous determination of dihydroxybenzene isomers, hydroquinone (HQ) and catechol (CC), in aqueous solution. Compared with the bare glassy carbon electrode (GCE), the electrodes modified with N,S-AGR showed enhanced electrochemical performance toward HQ and CC in both cyclic voltammetric (CV) and differential pulse voltammetric (DPV) measurements because of their enlarged surface area, enhanced electron-transfer rate and increased active sites. Compared with some recently reported electrochemical sensors based on graphene composites, the N,S-AGR modified electrode exhibits higher sensitivity, a much lower detection limit and a comparable linear range for the simultaneous determination of HQ and CC. Moreover, the proposed sensor is promising in practical application for the satisfactory recoveries obtained in real water sample analyses.

  20. Influence of catechol-o-methyltransferase genotype (Val158Met) on endocrine, sympathetic nervous and mucosal immune systems in breast cancer survivors.

    PubMed

    Fernández-de-Las-Peñas, César; Cantarero-Villanueva, Irene; Fernández-Lao, Carolina; Ambite-Quesada, Silvia; Díaz-Rodríguez, Lourdes; Rivas-Martínez, Inés; del Moral-Avila, Rosario; Arroyo-Morales, Manuel

    2012-04-01

    Stress can play an important role in development of cancer-related fatigue (CRF) by activating the hypothalamic-pituitary-adrenal (HPA) axis, the sympathetic nervous system (SNS), and altering the immune system. This study examined the influence of catechol-O-methyltransferase (COMT) Val158Met genotypes on salivary markers of HPA axis (cortisol), SNS (α-amylase) and immune (IgA) systems, as well as on CRF in breast cancer survivors (BCS). One-hundred BCS participated. After amplifying Val158Met COMT polymorphisms by polymerase chain reaction, three COMT genotypes were considered: Val/Val, Val/Met, Met/Met. Salivary cortisol, α-amylase activity, salivary flow rate, and IgA concentration were collected from non-stimulated saliva. CRF was assessed with the fatigue subscale of the Profile of Mood State (POMS) questionnaire. We found that BCS carrying Met/Met genotype reported higher cortisol concentration, α-amylase activity and greater CRF than those with Val/Met (P < 0.05) and Val/Val (P < 0.001) genotypes. No differences in salivary flow rate or IgA concentration (P > 0.20) were found. The results suggest that BCS carrying Met/Met genotype exhibit greater dysfunction of the HPA axis and SNS system associated with severe CRF. This study is important because it strives to understand biological factors that predispose some BCS to higher levels of CRF. PMID:21974969

  1. Catecholate-siderophore produced by As-resistant bacterium effectively dissolved FeAsO4 and promoted Pteris vittata growth.

    PubMed

    Liu, Xue; Yang, Guang-Mei; Guan, Dong-Xing; Ghosh, Piyasa; Ma, Lena Q

    2015-11-01

    The impact of siderophore produced by arsenic-resistant bacterium Pseudomonas PG12 on FeAsO4 dissolution and plant growth were examined. Arsenic-hyperaccumulator Pteris vittata was grown for 7 d in 0.2-strength Fe-free Hoagland solution containing FeAsO4 mineral and PG12-siderophore or fungal-siderophore desferrioxamine B (DFOB). Standard siderophore assays indicated that PG12-siderophore was catecholate-type. PG12-siderophore was more effective in promoting FeAsO4 dissolution, and Fe and As plant uptake than DFOB. Media soluble Fe and As in PG12 treatment were 34.6 and 3.07 μM, 1.6- and 1.4-fold of that in DFOB. Plant Fe content increased from 2.93 to 6.24 g kg(-1) in the roots and As content increased from 14.3 to 78.5 mg kg(-1) in the fronds. Besides, P. vittata in PG12 treatment showed 2.6-times greater biomass than DFOB. While P. vittata fronds in PG12 treatment were dominated by AsIII, those in DFOB treatment were dominated by AsV (61-77%). This study showed that siderophore-producing arsenic-resistant rhizobacteria may have potential in enhancing phytoremediation of arsenic-contaminated soils. PMID:26247380

  2. Electrochemical behavior of catechol and 3,4-dihydroxytoluene in acetonitrile at a platinum-disk electrode modified with a tyrosinase containing polyacrylamide film.

    PubMed

    Miyasaka, T; Takahashi, Y; Nakamura, T

    2001-09-01

    A modified platinum-disk electrode coated with a non-plasticized polyacrylamide (PAA) membrane was used to study electrochemically an enzymatic reaction between tyrosinase in the PAA membrane and catechol and 3,4-dihydroxytoluene in acetonitrile (AN). Tyrosinase, a hydrophilic biofunctional material, was immobilized in the thin PAA membrane, which adhered to the platinum-disk electrode and was stable in AN. The enzymatic activity of tyrosinase in the PAA membrane to the above substrates in AN was confirmed by cyclic voltammetry and amperometry. The apparent maximum velocities (Vmaxapp) and the apparent Michaelis constants (Kmapp) were determined from the amperometric results; the apparent turnover numbers were also determined. The reduction potentials of the substrates were reported vs. the cathodic peak potential of ferrocene in AN to improve the reliability of the potential data and to make possible a comparison of the potentials in different solvents. The electrochemical system discussed in this report can be used for tracing enzymatic reactions with substrates dissolving in aprotic dipolar solvents and for investigating solvent effects on enzymatic activities.

  3. The syntheses and characterizations of molybdenum(VI) complexes with catechol and 2,3-dihydroxynaphthalene, and the structure-effect relationship in their in vitro anticancer activities.

    PubMed

    Feng, Jun; Lu, Xiao-ming; Wang, Guo; Du, Shi-zhen; Cheng, Yi-feng

    2012-07-28

    The reactions of (NH(4))(2)Mo(2)O(7)·2H(2)O with polyhydroxy phenols (catechol or 2,3-dihydroxynaphthalene) and ethylenediamine (en), trimethylenediamine (tn), 1,2-propanediamine (pn), triethylamine (Et(3)N) respectively, in the mixed-solvent of MeCN-EtOH-amine, have resulted in five molybdenum(VI) complexes, (enH(2))[Mo(VI)O(3)(cat)(en)] (1), (tnH(2))[Mo(VI)O(3)(cat)(tn)] (2), (enH)(2)[Mo(VI)O(2)(cat)(2)](en)(0.5) (3), (pnH(2))(2)[Mo(VI)O(2)(cat)(2)] (4) and (HNEt(3))(2)[Mo(VI)O(2)(C(10)H(8)O(2))(2)] (5), of which the structural features were investigated by X-ray diffraction. MTT assay tests indicated that their inhibition ratios against human cancer cells decreased in the order: (1) ≈ (2) > (3) ≈ (4) > (5), i.e. the activities decreased when the chelation number or the size of the aromatic ligand increased, which was consistent with the Gibbs free energies (ΔG) determined from theoretical computations by Gaussian 03. The mechanisms behind this trend were discussed preliminarily.

  4. Concerted action of the cytosolic sulfotransferase, SULT1A3, and catechol-O-methyltransferase in the metabolism of dopamine in SK-N-MC human neuroblastoma cells.

    PubMed

    Yasuda, Shin; Yasuda, Tomoko; Hui, Ying; Liu, Ming-Yih; Suiko, Masahito; Sakakibara, Yoichi; Liu, Ming-Cheh

    2009-07-01

    Conjugation reactions catalyzed by the cytosolic sulfotransferase, SULT1A3, or catechol-O-methyltransferase (COMT) are known to be involved in the regulation and homeostasis of dopamine and other monoamine neurotransmitters. Whether different conjugation reactions may act in a concerted manner, however, remains unclear. The current study aimed to investigate the concerted action of SULT1A3 and COMT in dopamine metabolism. Analysis of the medium of SK-N-MC cells, metabolically labeled with [(35)S]sulfate in the presence of dopamine, revealed the generation and release of predominantly [(35)S]sulfated 3-methyldopamine and, to a lesser extent [(35)S]sulfated dopamine. Addition to the labeling medium of tropolone, a COMT inhibitor, enhanced the production of [(35)S]sulfated dopamine, with a concomitant decrease of [(35)S]sulfated 3-methyldopamine. Enzymatic assays using the eleven known human cytosolic SULTs revealed SULT1A3 as the major enzyme responsible for the sulfation of both dopamine and 3-methyldopamine. Kinetic analysis showed that the catalytic efficiency of SULT1A3 with 3-methyldopamine was 1.6 times than that with dopamine. Using subcellular fractions prepared from SK-N-MC cells, the majority of COMT dopamine-methylating activity was found to be present in the cytosol. Collectively, these results imply a concerted action of sulfation and methylation in the irreversible inactivation and disposal of excess dopamine in SK-N-MC cells.

  5. Antiproliferative activity, cell-cycle dysregulation, and cellular differentiation: salicyl- and catechol-derived acyclic 5-fluorouracil O,N-acetals against breast cancer cells.

    PubMed

    Marchal, Juan A; Rodríguez-Serrano, Fernando; Caba, Octavio; Aránega, Antonia; Gallo, Miguel A; Espinosa, Antonio; Campos, Joaquín M

    2007-12-01

    Herein we report the preparation and biological activity of three compounds with the general formula 1-[2-(5-substituted-2-hydroxybenzyloxy)-1-methoxyethyl]-5-fluorouracil. A catechol-derived compound such as 1-[3-(2-hydroxyphenoxy)-1-methoxypropyl]-5-fluorouracil and two salicyl-derived compounds such as (Z)-1-[4-(2-hydroxyphenyl)-1-methoxybut-3-enyl]-5-fluorouracil [(Z)-11] and its dihydrogenated derivative 1-[4-(2-hydroxyphenyl)-1-methoxybutyl]-5-fluorouracil were prepared to complete the set of six O,N-acetals. The most active compound against the MCF-7 breast cancer cell line was (Z)-11: IC(50)=9.40+/-0.64 microM. Differentiated breast cancer cells generate fat deposits in the cytoplasm. MCF-7 cells treated with (Z)-11 underwent an increase in lipid content relative to control cells after three days of treatment. Our results suggest that there may be significant potential advantages in the use of this new differentiating agent for the treatment of breast cancer.

  6. Influence of catechol-O-methyltransferase Val158Met polymorphism on neuropsychological and functional outcomes of classical rehabilitation and cognitive remediation in schizophrenia.

    PubMed

    Bosia, Marta; Bechi, Margherita; Marino, Elena; Anselmetti, Simona; Poletti, Sara; Cocchi, Federica; Smeraldi, Enrico; Cavallaro, Roberto

    2007-05-01

    Neurocognitive deficits are recognized as core features of schizophrenia and have a great impact on functional outcome. Recent reports have suggested that a functional polymorphism, Val158Met, of the catechol-O-methyltransferase (COMT) gene, partially influences cognitive performances (mainly cognitive flexibility and working memory) both in schizophrenic patients and in healthy controls, probably by modulating prefrontal dopamine function. While previous studies focused on single evaluation of cognitive functioning, we aimed to analyse the additive effect of COMT genotype and cognitive exercise on dynamic modulation of cognitive performances. We analysed the COMT Val158Met polymorphism in 50 patients with chronic schizophrenia randomly allocated to two treatment conditions for 3 months: standard rehabilitation treatment (SRT) alone and SRT plus specific cognitive exercise of impaired functions. We then divided our sample in four subgroups on the basis of genotype (Val/Val versus Met carriers) and treatment (placebo versus active). We assessed patients with a neuropsychological battery, the Positive and Negative Symptoms Scale (PANSS) and the Quality of Life Scale (QLS) at enrolment, after 3 months of therapy and after further 3 months of follow-up. We found significantly greater improvement of cognitive flexibility performance and QLS total score for Met carriers on active treatment in comparison to Val/Val on placebo. The findings support the hypothesis that COMT polymorphism influences individual capacity to recover from cognitive deficit through rehabilitation therapy after a wider intervention also including deficit-specific cognitive exercise as a potentiating tool.

  7. Association between the Catechol-O-Methyltransferase (COMT) Val158Met Polymorphism and Alexithymia in Patients with Obsessive-Compulsive Disorder

    PubMed Central

    Koh, Min Jung; Kang, Jee In; Namkoong, Kee; Lee, Su Young

    2016-01-01

    Purpose Alexithymia, defined as a deficit in the ability to recognize and describe one's own feelings, may be related to the development and maintenance of obsessive-compulsive symptoms. The aim of this study was to evaluate the association between the catechol-O-methyltransferase (COMT) Val158Met polymorphism and alexithymia in patients with obsessive-compulsive disorder (OCD). Materials and Methods We recruited 244 patients with OCD (169 males, 75 females). Alexithymia was assessed using the 20-item Toronto Alexithymia Scale (TAS-20), and genotyping of the COMT Val158Met polymorphism was evaluated. Results Patients with the COMT Val/Val genotype had significantly higher total and "difficulty identifying feelings" (DIF) subdimension scores than those with the Val/Met or Met/Met genotypes. Patients with the COMT Val/Val genotype had significantly higher "difficulty describing feelings" (DDF) subdimension scores than those with the COMT Val/Met genotype. However, there were no differences in the scores for the "externally oriented thinking" (EOT) subdimension among the three genotypes. Conclusion These results indicate that the high-activity Val allele of the COMT Val158Met polymorphism is associated with increased alexithymic traits in patients with OCD. The present finding suggests that alexithymia is an endophenotype of OCD that is mediated by the COMT Val158Met polymorphism. PMID:26996573

  8. Acute antidepressant response to sleep deprivation combined with light therapy is influenced by the catechol-O-methyltransferase Val(108/158)Met polymorphism.

    PubMed

    Benedetti, Francesco; Barbini, Barbara; Bernasconi, Alessandro; Fulgosi, Mara Cigala; Dallaspezia, Sara; Gavinelli, Chiara; Locatelli, Clara; Lorenzi, Cristina; Pirovano, Adele; Radaelli, Daniele; Smeraldi, Enrico; Colombo, Cristina

    2010-02-01

    Catechol-O-methyltransferase (COMT) inactivates norepinephrine and dopamine via methyl conjugation, and a G-A transition in the COMT gene (rs4680) influences the enzyme activity. It is a current area of debate whether rs4680 can influence antidepressant response in major depressive disorder, and whether this influence extends to bipolar depression. Chronotherapeutic interventions, such as sleep deprivation and light therapy, are multi-target in nature and are effective in bipolar depression. Here we studied the effect of rs4680 on response to sleep deprivation combined with light therapy (36 h awake followed by a night of undisturbed sleep, with 10,000 lx light administered for 30 min during the night awake and upon awakening) in 87 bipolar depressed inpatients. Patients who were homozygotic for the Val/Val variant showed a significantly less efficient antidepressant effect after the night awake than those who were heterozygotic and homozygotic for the Met variant. This effect of rs4680 is similar to its observed influence on response to serotonergic and noradrenergic drug treatments in major depressive disorder. This is the first study reporting an influence of rs4680 on antidepressant response in bipolar depression. This finding supports the hypothesis of a major role for catecholamines in the mechanism of action of chronotherapeutics, and for rs4680 in modulating this effect.

  9. Ligand centered radical pathway in catechol oxidase activity with a trinuclear zinc-based model: Synthesis, structural characterization and luminescence properties

    NASA Astrophysics Data System (ADS)

    Pal, Sukanta; Chowdhury, Biswajit; Patra, Moumita; Maji, Milan; Biswas, Bhaskar

    2015-06-01

    A new trinuclear zinc(II) complex, [Zn3(L)(NCS)2](NO3)2·CH3OH·H2O (1), of a (N,O)-donor compartmental Schiff base ligand (H2L = N,N‧-bis(3-methoxysalicylidene)-1,3-diamino-2-propanol), has been synthesized in crystalline phase. The zinc(II) complex has been characterized by elemental analysis, IR spectroscopy, UV-Vis spectroscopy, powder X-ray diffraction study (PXRD), 1H NMR, EI mass spectrometry and thermogravimetric analysis. PXRD revealed that 1 crystallizes in P - 1 space group with a = 9.218 Å, b = 10.849 Å, c = 18.339 Å, with unit cell volume is 2179.713 (Å)3. Fluorescence spectra in methanolic solution reflect that intensity of emission for 1 is much higher compared to H2L and both the compounds exhibit good fluorescence properties. The complex 1 exhibits significant catalytic activities of biological relevance, viz. catechol oxidase. In methanol, it efficiently catalyzes the oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) to corresponding quinone via formation of a dinuclear species as [Zn2(L)(3,5-DTBC)]. Electron Paramagnetic Resonance (EPR) experiment suggests generation of radicals in the presence of 3,5-DTBC and it may be proposed that the radical pathway is probably responsible for conversion of 3,5-DTBC to 3,5-DTBQ promoted by complex of redox-innocent Zn(II) ion.

  10. The impact of the Catechol-O-methyltransferase Val158Met polymorphism on survival in the general population – the HUNT study

    PubMed Central

    Hagen, Knut; Stovner, Lars J; Skorpen, Frank; Pettersen, Elin; Zwart, John-Anker

    2007-01-01

    Background The catechol-O-methyltransferase (COMT) gene contains a functional polymorphism, Val158Met which has been related to common diseases like cancer, psychiatric illness and myocardial infarction. Whether the Val158Met polymorphism is associated with survival has not been evaluated in the general population. The aim of this prospective study was to evaluate the impact of codon 158 COMT gene polymorphism on survival in a population-based cohort. Methods The sample comprised 2979 non-diabetic individuals who participated in the Nord-Trøndelag Health Study (HUNT) in the period 1995–97. The subjects were followed up with respect to mortality throughout year 2004. Results 212 men and 183 women died during the follow up. No association between codon 158 COMT gene polymorphism and survival was found. The unadjusted relative risk of death by non-ischemic heart diseases with Met/Met or Met/Val genotypes was 3.27 (95% confidence interval, 1.19–9.00) compared to Val/Val genotype. When we adjusted for age, gender, smoking, coffee intake and body mass index the relative risk decreased to 2.89 (95% confidence interval, 1.04–8.00). Conclusion During 10 year of follow-up, the Val158Met polymorphism had no impact on survival in a general population. Difference in mortality rates from non-ischemic heart diseases may be incidental and should be evaluated in other studies. PMID:17577421

  11. A new iron(III) complex of glycine derivative of amine-chloro substituted phenol ligand: Synthesis, characterization and catechol dioxygenase activity

    NASA Astrophysics Data System (ADS)

    Saberikia, Iraj; Safaei, Elham; Kowsari, Mohammad Hossein; Lee, Yong-Ill; Cotic, Patricia; Bruno, Giuseppe; Rudbari, Hadi Amiri

    2012-12-01

    A new iron(III) complex of the glycine derivative of amine-chloro substituted phenol ligand (H3LGDC) has been prepared and characterized by IR, 1H NMR, UV-Vis spectroscopic techniques, cyclic voltammetry, ESI-MS and magnetic susceptibility studies. X-ray analysis reveals that in iron complex of FeLGDC the iron(III) center has a distorted trigonal bipyramidal coordination sphere and is surrounded by an amine nitrogen, a carboxylate, a water and two phenolate oxygen atoms. The DFT calculations with the UB3LYP/6-311++G** level optimized structure of the complex are in good agreement with experimental X-ray structural data. The variable-temperature magnetic susceptibility indicates that FeLGDC is the paramagnetic high spin iron(III) complex. It has been shown that electrochemical oxidation of this complex is ligand-centered due to the oxidation of phenolate to the phenoxyl radicals. This enzyme mimic utilized molecular oxygen in carrying out the oxidative cleavage of catechols with complete conversion at room temperature.

  12. Convergent Mechanistic Features between the Structurally Diverse N- and O-Methyltransferases: Glycine N-Methyltransferase and Catechol O-Methyltransferase.

    PubMed

    Zhang, Jianyu; Klinman, Judith P

    2016-07-27

    Although an enormous and still growing number of biologically diverse methyltransferases have been reported and identified, a comprehensive understanding of the enzymatic methyl transfer mechanism is still lacking. Glycine N-methyltransferase (GNMT), a member of the family that acts on small metabolites as the substrate, catalyzes methyl transfer from S-adenosyl-l-methionine (AdoMet) to glycine to form S-adenosyl-l-homocysteine and sarcosine. We report primary carbon ((12)C/(14)C) and secondary ((1)H3/(3)H3) kinetic isotope effects at the transferred methyl group, together with (1)H3/(3)H3 binding isotope effects for wild-type GNMT and a series of Tyr21 mutants. The data implicate a compaction effect in the methyl transfer step that is conferred by the protein structure. Furthermore, a remarkable similarity of properties is observed between GNMT and catechol O-methyltransferase, despite significant differences between these enzymes with regard to their active site structures and catalyzed reactions. We attribute these results to a catalytically relevant reduction in the methyl donor-acceptor distance that is dependent on a tyrosine side chain positioned behind the methyl-bearing sulfur of AdoMet. PMID:27355841

  13. Iron(III) complex of N-phenylethylenediamine derivative of amine bis(phenol) ligand as model for catechol dioxygenase: Synthesis, characterization and complexation studies

    NASA Astrophysics Data System (ADS)

    Poureskandari, Maryam; Safaei, Elham; Maryam Sajjadi, S.; Karimpour, Touraj; Jaglicic, Zvonko; Lee, Yong-Ill

    2015-08-01

    A new amine bis(phenol) ligand (HLPEA), was synthesized and characterized by IR, 1H NMR spectroscopic techniques and elemental analyses. The mononuclear iron(III) complex (FeLPEA) of this ligand has been prepared and characterized by IR and UV-Vis spectroscopic techniques, ESI-MS, elemental analyses and magnetic susceptibility studies. The molecular mass of complex was determined by ESI-MS which is corresponding to a mononuclear iron(III) complex consist of amine bis(phenolate) ligand coordinated to Fe(III) including chlorine atoms and solvent molecule. The variable temperature magnetic susceptibility indicates paramagnetic character of complex. To determine the formation constant of the complex, multivariate hard modeling method was applied on spectral data collected throughout the titration of Fe(III) with ligand. FeLPEA shows good catalytic activity in cleavage oxygenation of 3,5-di-tert-butyl catechol in the presence of dioxygen at room temperature with a nearly complete conversion and particularly extradiol cleavage mechanism.

  14. Effect of surfactant-induced cell surface modifications on electron transport system and catechol 1,2-dioxygenase activities and phenanthrene biodegradation by Citrobacter sp. SA01.

    PubMed

    Li, Feng; Zhu, Lizhong

    2012-11-01

    In order to better understand how surfactants affect biodegradation of hydrophobic organic compounds (HOCs), Tween 80 and sodium dodecyl benzene sulfonate (SDBS), were selected to investigate effects on cell surface hydrophobicity (CSH), electron transport system (ETS) activities and phenanthrene biodegradation by Citrobacter sp. SA01. Tween 80 and SDBS increased CSH by 19.8-25.2%, ETS activities by 352.1-376.0μmol/gmin, catechol 1,2-dioxygenase (C12) activities by 50.8-52.7U/L, and phenanthrene biodegradation by 8.9-17.2% separately in the presence of 50mg/L of surfactants as compared to in their absence. Lipopolysaccharide (LPS) release was 334.7μg/mg in the presence of both surfactants whereas in their absence only 8.6-44.4μg/mg of LPS was released. Thus, enhanced LPS release probably increased ETS and C12 activities as well as phenanthrene biodegradation by increasing CSH. The results demonstrate that surfactant-enhanced CSH provides a simple, yet effective strategy for field applications of surfactant-enhanced bioremediation of HOCs.

  15. Electrochemical biosensing platform based on amino acid ionic liquid functionalized graphene for ultrasensitive biosensing applications.

    PubMed

    Lu, Xianbo; Wang, Xue; Jin, Jing; Zhang, Qing; Chen, Jiping

    2014-12-15

    In this study, a facile non-covalent method was developed for preparing water-soluble graphene with excellent electronic conductivity. Room temperature ionic liquids (ILs) with high ionic conductivity were used for the non-covalent surface functionalization of graphene through π-π stacking interactions. Compared to other ILs used, amino acid ionic liquids (AAILs) were found to be the most effective for improving the dispersion of graphene in water phase. Electrochemical and spectroscopic results confirmed that the obtained AAIL functionalized GR can retain the excellent electronic conductivity of pristine graphene without damaging the graphene lattice. The obtained water-soluble graphene (GR-AAIL) was exemplified to fabricate an electrochemical biosensor using tyrosinase as a model enzyme, and the sensitivity (12,600 mA cm(-2) M(-1)) of GR-AAIL based biosensor was about 17 times higher than that of graphene oxide and other nanomaterial based biosensor, displaying its unprecedented high sensitivity for biosensing. The detection limit for catechol (one important environmental pollutant) reached as low as 8 nM with a response time of 3s and a linear range from 25 nM to 11,100 nM. The AAIL-GR based biosensor also demonstrated good reproducibility, repeatability, selectivity, long-term stability and high recovery for catechol detection. Amino acid ionic liquid functionalized graphene proves to be a robust and versatile electrochemical biosensing platform for fabricating biosensors with excellent performance.

  16. Muconic acid production from glucose using enterobactin precursors in Escherichia coli.

    PubMed

    Wang, Jie; Zheng, Pu

    2015-05-01

    Muconic acid (MA) is a promising bulk chemical due to its extensive industrial applications in the production of adipic acid and other valuable, biodegradable intermediates. MA is heretofore mainly produced from petrochemicals by organic reactions which are not environmentally friendly or renewable. Biological production processes provide a promising alternative for MA production. We designed an artificial pathway in Escherichia coli for the biosynthesis of MA using the catechol group of 2,3-dihydroxybenzoate, an intermediate in the enterobactin biosynthesis pathway. This approach consists of two heterologous microbial enzymes, including 2,3-dihydroxybenzoate decarboxylase and catechol 1,2-dioxygenase. The metabolic flow of carbon into the heterologous pathway was optimized by increasing the flux from chorismate through the enterobactin biosynthesis pathway and by regulating the shikimate pathway. Metabolic optimization enabled a concentration of 605.18 mg/L of MA from glucose in a shaking flask culture, a value nearly 484-fold higher than that of the initial recombinant strain. The results indicated that the production of MA from this pathway has the potential for further improvement. PMID:25663483

  17. Muconic acid production from glucose using enterobactin precursors in Escherichia coli.

    PubMed

    Wang, Jie; Zheng, Pu

    2015-05-01

    Muconic acid (MA) is a promising bulk chemical due to its extensive industrial applications in the production of adipic acid and other valuable, biodegradable intermediates. MA is heretofore mainly produced from petrochemicals by organic reactions which are not environmentally friendly or renewable. Biological production processes provide a promising alternative for MA production. We designed an artificial pathway in Escherichia coli for the biosynthesis of MA using the catechol group of 2,3-dihydroxybenzoate, an intermediate in the enterobactin biosynthesis pathway. This approach consists of two heterologous microbial enzymes, including 2,3-dihydroxybenzoate decarboxylase and catechol 1,2-dioxygenase. The metabolic flow of carbon into the heterologous pathway was optimized by increasing the flux from chorismate through the enterobactin biosynthesis pathway and by regulating the shikimate pathway. Metabolic optimization enabled a concentration of 605.18 mg/L of MA from glucose in a shaking flask culture, a value nearly 484-fold higher than that of the initial recombinant strain. The results indicated that the production of MA from this pathway has the potential for further improvement.

  18. Coating morphology and surface composition of acrylic terpolymers with pendant catechol, OEG and perfluoroalkyl groups in varying ratio and the effect on protein adsorption.

    PubMed

    Zhong, Jun; Ji, Hua; Duan, Jiang; Tu, Haiyang; Zhang, Aidong

    2016-04-01

    This work aims at developing versatile low-biofouling polymeric coatings by using acrylic terpolymers (DOFs) that bear pendant catechol (D), oligo(ethylene glycol) (O), and perfluoroalkyl (F) groups in varying ratios. The polymers were endowed with the ability to form firmly coatings on virtually any surfaces and undergo surface microphase separation and self-assembly, as revealed by the surface enrichment of F pendants and the morphology variation from irregular solid domains to discrete crater-type aggregates of different size. The effect on protein adsorption was investigated using bovine serum albumin (BSA) and adhesive fibrinogen (Fib) as model proteins. The coating of DOF164 (low F content), which has morphology of discrete crater-type aggregates of ∼ 400 nm in size, adsorbed a least amount of protein but with a highest protein unit activity as determined by SPR and immunosorbent assay; whereas the coating of DOF1612 (high F content) showed a 12.3-fold higher adsorption capacity toward Fib. Interestingly, a 2.2-fold lower adsorption amount but with a 1.8-fold higher unit activity was found for Fib adsorbed on the DOF164 surface than on DOF250 (without F fraction), whose OEG segments being a widely recognized protein compatible material. The features of the DOF164 terpolymer presenting a robust coating ability and a minimal protein adsorption capacity while with a high protein unit activity suggest its potential application as a non-fouling surface-modifier for medical antifouling coatings and as a matrix material for selective protein immobilization and activity preservation in biosensor construction. PMID:26764109

  19. Effect of catechol-O-methyltransferase-val158met-polymorphism on the automatization of motor skills - a post hoc view on an experimental data.

    PubMed

    Krause, Daniel; Beck, Frieder; Agethen, Manfred; Blischke, Klaus

    2014-06-01

    The purpose of this study was to evaluate if the catechol-O-methyltransferase-val158met (COMT)-polymorphism, which is known to affect prefrontal dopaminergic metabolism, affects the automatization of motor skills. Twenty-two participants volunteered for gene analysis after they had participated in experiments in which they practiced a single-joint arm movement sequence 460-760 times under different feedback conditions. Motor automaticity was assessed in a pre-test and a post-test according to the dual-task paradigm, which incorporated a visuo-spatial secondary task. To account for the different practice conditions in the four original studies, dual-task cost reduction was assessed using single case effect sizes proportioned to the respective group mean. For the secondary task but not for the prioritized motor task, these relative single case effect sizes proved to be positively (and significantly) correlated with the number of met-alleles on the COMT-genotype, rs=.553; p=.004. Thus, the number of met-alleles indicated a tendency toward enhanced motor automatization. Thus, due to an increased prefrontal dopamine level, met-carriers may be able to develop a well formed and stable, spatially coded movement representation early in practice, thereby supporting the formation of a representation in motor coordinates in the course of extended practice, which later enables automatic movement execution. This process might also be enhanced by a prevalence of met-carriers to functionally evaluate positive feedback information (i.e., rewards) and to better maintain recent reward information in active working memory. PMID:24607512

  20. Catechol-O-methyltransferase gene variants may associate with negative symptom response and plasma concentrations of prolactin in schizophrenia after amisulpride treatment.

    PubMed

    Chen, Chun-Yen; Yeh, Yi-Wei; Kuo, Shin-Chang; Ho, Pei-Shen; Liang, Chih-Sung; Yen, Che-Hung; Lu, Ru-Band; Huang, San-Yuan

    2016-03-01

    Catechol-O-methyltransferase (COMT) enzyme is involved in the pathogenesis of psychotic symptoms and may be associated with a therapeutic response to antipsychotic drugs. The aim of this study was to examine the relationship between COMT variants, plasma prolactin level, and the therapeutic effectiveness of amisulpride treatment in patients with schizophrenia. A 12-week naturalistic study of amisulpride treatment was carried out in 185 Han Chinese patients with schizophrenia. The patients were screened for 14 single-nucleotide polymorphisms of the COMT gene. The Positive and Negative Syndrome Scale (PANSS) was used to assess the improvement of psychopathological symptoms from the baseline to the end point in each subject. For better presentation of time-course changes in response status, a mixed model for repeated-measures (MMRM) analysis of symptom improvement during the 12-week treatment period was conducted. The change in plasma prolactin level after amisulpride treatment was also examined (n=51). No significant differences in the genotype frequencies of the COMT variants investigated were observed between responders and non-responders. Moreover, an MMRM analysis of psychopathological symptom improvement during the 12-week treatment course showed that it depended significantly on COMT variants (rs4680, rs4633, and rs6267), particularly regarding changes in negative symptoms. The increase in plasma prolactin levels observed was influenced by the COMT rs4680 variant and was positively correlated with a reduction in PANSS negative scores. Our results suggest that variation of the COMT gene is associated with treatment response regarding negative symptoms and prolactin changes after amisulpride treatment in patients with schizophrenia.

  1. Meta-analysis reveals a lack of association between a common catechol-O-methyltransferase (COMT) polymorphism val¹⁵⁸met and fibromyalgia.

    PubMed

    Zhang, Lei; Zhu, Junwei; Chen, Yong; Zhao, Jianning

    2014-01-01

    This study is to evaluate the association between the catechol-O-methyltransferase (COMT) gene val(158)met polymorphism and FM risk. We performed a meta-analysis of 8 case-control studies that included 589 FM cases and 527 case-free controls. We assessed the strength of the association, using odds ratios (ORs) with 95% confidence intervals (CIs). Overall, this meta-analysis showed that the COMT gene val(158)met polymorphism was not associated with FM risk in all genetic models, i.e., allele (met vs. val: OR=1.46, 95% CI=0.80-2.66, P heterpgeneity<0.001), homozygous (met/met vs. val/val: OR=1.72, 95% CI=0.61-4.87, P heterpgeneity<0.001), heterozygous (val/met vs. val/val: OR=1.25, 95% CI=0.82-1.92, P heterpgeneity=0.050), recessive (met/met vs. val/val+val/met: OR=1.52, 95% CI=0.60-3.86, P heterpgeneity<0.001) and dominant model (met/met+val/met vs. val/val: OR=1.52, 95% CI=0.80-2.90, P heterpgeneity<0.001). Similarly, there were no significant associations in the subgroup analyses by ethnicity and HWE. No publication bias was found in the present study. This meta-analysis suggests that the COMT gene val(158)met polymorphism is not associated with FM risk. Further large and well-designed studies are needed to confirm this association.

  2. How to consistently link extraversion and intelligence to the catechol-O-methyltransferase (COMT) gene: on defining and measuring psychological phenotypes in neurogenetic research.

    PubMed

    Wacker, Jan; Mueller, Erik M; Hennig, Jürgen; Stemmler, Gerhard

    2012-02-01

    The evidence for associations between genetic polymorphisms and complex behavioral/psychological phenotypes (traits) has thus far been weak and inconsistent. Using the well-studied Val158Met polymorphism of the catechol-O-methyltransferase (COMT) gene as an example, we demonstrate that using theoretical models to guide phenotype definition and measuring the phenotypes of interest with a high degree of specificity reveals strong gene-behavior associations that are consistent with prior work and that would have otherwise gone unnoticed. Only after statistically controlling for irrelevant portions of phenotype variance did we observe strong (Cohen's d = 0.33-0.70) and significant associations between COMT Val158Met and both cognitive and affective traits in a healthy male sample (N = 201) in Study 1: Carriers of the Met allele scored higher in fluid intelligence (reasoning) but lower in both crystallized intelligence (general knowledge) and the agency facet of extraversion. In Study 2, we conceptually replicated the association of COMT Val158Met with the agency facet of extraversion after partialing irrelevant phenotype variance in a female sample (N = 565). Finally, through reanalysis of a large published data set we showed that Met allele carriers also scored higher in indicators of fluid intelligence after partialing verbal fluency. Because the Met allele codes for a less efficient variant of the enzyme COMT, resulting in higher levels of extrasynaptic prefrontal dopamine, these observations provide further support for a role for dopamine in both intelligence and extraversion. More importantly, the present findings have important implications for the definition of psychological phenotypes in neurogenetic research.

  3. The effects of 8-arm-PEG-catechol/heparin shielding system and immunosuppressive drug, FK506 on the survival of intraportally allotransplanted islets.

    PubMed

    Im, Bok-Hyeon; Jeong, Jee-Heon; Haque, Muhammad R; Lee, Dong Yun; Ahn, Cheol-Hee; Kim, Ju Eun; Byun, Youngro

    2013-03-01

    This study proposed a double-layer shielding method of using 8-arm-PEG-catechol (PEG(8)) and N-hydroxysuccinimidyl-linked unfractionated heparin (UFH-NHS) for the prevention of instant blood-mediated inflammatory reaction (IBMIR) and immune reactions against transplanted pancreatic islets. The surface of islet was evenly covered by PEG(8) and UFH-NHS. Both viability and functionality of islets were evaluated in vitro, and the anti-coagulation effect of conjugated heparin on the islet surface was also evaluated. The inhibition effects of PEG(8)/UFH double-layer shielding system on immune reactions and IBMIR induced by transplanted islets were evaluated in an allograft model. When pancreatic islets of Sprague-Dawley (SD) rats were transplanted in the liver of F344 rats, the mean survival time (MST) of PEG(8)/UFH double-layer shielded islets (6.8 ± 1.6 days) was statistically increased, compared to that of unmodified islets (3.6 ± 1.1 days). Furthermore, when 0.5 mg/kg of FK506 was daily administered, the MST of double-layer shielded islet (15.0 ± 2.1 days) was increased by two-fold, compared to that of unmodified islets treated with the same dose of FK506 (8.0 ± 2.4 days). Therefore, a newly developed strategy of combining the PEG(8)/UFH double-layer shielding system with FK506 would certainly be effective for preventing immune activation and IBMIR against allotransplanted islets.

  4. Phase II metabolism in human skin: skin explants show full coverage for glucuronidation, sulfation, N-acetylation, catechol methylation, and glutathione conjugation.

    PubMed

    Manevski, Nenad; Swart, Piet; Balavenkatraman, Kamal Kumar; Bertschi, Barbara; Camenisch, Gian; Kretz, Olivier; Schiller, Hilmar; Walles, Markus; Ling, Barbara; Wettstein, Reto; Schaefer, Dirk J; Itin, Peter; Ashton-Chess, Joanna; Pognan, Francois; Wolf, Armin; Litherland, Karine

    2015-01-01

    Although skin is the largest organ of the human body, cutaneous drug metabolism is often overlooked, and existing experimental models are insufficiently validated. This proof-of-concept study investigated phase II biotransformation of 11 test substrates in fresh full-thickness human skin explants, a model containing all skin cell types. Results show that skin explants have significant capacity for glucuronidation, sulfation, N-acetylation, catechol methylation, and glutathione conjugation. Novel skin metabolites were identified, including acyl glucuronides of indomethacin and diclofenac, glucuronides of 17β-estradiol, N-acetylprocainamide, and methoxy derivatives of 4-nitrocatechol and 2,3-dihydroxynaphthalene. Measured activities for 10 μM substrate incubations spanned a 1000-fold: from the highest 4.758 pmol·mg skin(-1)·h(-1) for p-toluidine N-acetylation to the lowest 0.006 pmol·mg skin(-1)·h(-1) for 17β-estradiol 17-glucuronidation. Interindividual variability was 1.4- to 13.0-fold, the highest being 4-methylumbelliferone and diclofenac glucuronidation. Reaction rates were generally linear up to 4 hours, although 24-hour incubations enabled detection of metabolites in trace amounts. All reactions were unaffected by the inclusion of cosubstrates, and freezing of the fresh skin led to loss of glucuronidation activity. The predicted whole-skin intrinsic metabolic clearances were significantly lower compared with corresponding whole-liver intrinsic clearances, suggesting a relatively limited contribution of the skin to the body's total systemic phase II enzyme-mediated metabolic clearance. Nevertheless, the fresh full-thickness skin explants represent a suitable model to study cutaneous phase II metabolism not only in drug elimination but also in toxicity, as formation of acyl glucuronides and sulfate conjugates could play a role in skin adverse reactions.

  5. Acyclonucleosides, modified seco-nucleosides, and salicyl- or catechol-derived acyclic 5-fluorouracil O,N-acetals: antiproliferative activities, cellular differentiation and apoptosis.

    PubMed

    Marchal, Juan A; Núñez, María C; Aránega, Antonia; Gallo, Miguel A; Espinosa, Antonio; Campos, Joaquín M

    2009-01-01

    The goal of cancer chemotherapy with classical drugs - the destruction of the tumor cells - is often complicated by significant toxicity. As an alternative, induced differentiation modulates the cell programme by transforming malignant cells into mature cells with no proliferative potential. Our data demonstrate that (+/-)-1-{[3-(2-hydroxyethoxy)-1-isopropoxy]propyl}-5-fluorouracil inhibits proliferation, induces myogenic differentiation, increases the expression of proteins specifically present in normally differentiated skeletal muscle cells, and modifies the adhesion capacity of these cells against the rhabdomyosarcoma cell line RD. From a designing point of view, a benzene ring was fused to the side chain in order to increase the lipophilicity and anticancer activity of our molecules. Herein we report the preparation and biological activity of three compounds having the general formula (+/-)-1-[2-(5-substituted-2-hydroxybenzyloxy)-1-methoxyethyl]-5-fluorouracils. A catechol-derived compound such as (+/-)-1-[3-(2-hydroxyphenoxy)-1-methoxypropyl]-5-fluorouracil and two salicyl-derived compounds such as (+/-)-(Z)-1-[4-(2-hydroxyphenyl)-1-methoxy-but-3-enyl]-5-fluorouracil [(Z)-43] and its dihydrogenated derivative (+/-)-1-[4-(2-hydroxyphenyl)-1-methoxybutyl]-5-fluorouracil were prepared to complete the set of six O,N-acetals. The most active compound against the MCF-7 breast cancer cell line was (+/-)-(Z)-43 with an IC(50) = 9.40 +/- 0.64 microM. Differentiated breast cancer cells generate fat deposits within the cytoplasm. The MCF-7 cells trea-ed with (+/-)-(Z)-43 caused an increase in the lipid content over control cells after 3 days of treatment. Our results suggest that there may be significant potential advantages in the use of this new differentiating agent for the treatment of breast cancer.

  6. Meta-analysis reveals a lack of association between a common catechol-O-methyltransferase (COMT) polymorphism val¹⁵⁸met and fibromyalgia.

    PubMed

    Zhang, Lei; Zhu, Junwei; Chen, Yong; Zhao, Jianning

    2014-01-01

    This study is to evaluate the association between the catechol-O-methyltransferase (COMT) gene val(158)met polymorphism and FM risk. We performed a meta-analysis of 8 case-control studies that included 589 FM cases and 527 case-free controls. We assessed the strength of the association, using odds ratios (ORs) with 95% confidence intervals (CIs). Overall, this meta-analysis showed that the COMT gene val(158)met polymorphism was not associated with FM risk in all genetic models, i.e., allele (met vs. val: OR=1.46, 95% CI=0.80-2.66, P heterpgeneity<0.001), homozygous (met/met vs. val/val: OR=1.72, 95% CI=0.61-4.87, P heterpgeneity<0.001), heterozygous (val/met vs. val/val: OR=1.25, 95% CI=0.82-1.92, P heterpgeneity=0.050), recessive (met/met vs. val/val+val/met: OR=1.52, 95% CI=0.60-3.86, P heterpgeneity<0.001) and dominant model (met/met+val/met vs. val/val: OR=1.52, 95% CI=0.80-2.90, P heterpgeneity<0.001). Similarly, there were no significant associations in the subgroup analyses by ethnicity and HWE. No publication bias was found in the present study. This meta-analysis suggests that the COMT gene val(158)met polymorphism is not associated with FM risk. Further large and well-designed studies are needed to confirm this association. PMID:25674213

  7. Effect of Catechol-O-methyltransferase-gene (COMT) Variants on Experimental and Acute Postoperative Pain in 1,000 Women undergoing Surgery for Breast Cancer

    PubMed Central

    Kambur, Oleg; Kaunisto, Mari A.; Tikkanen, Emmi; Leal, Suzanne M.; Ripatti, Samuli; Kalso, Eija A.

    2016-01-01

    Background Catechol-O-methyltransferase (COMT) metabolizes catecholamines in different tissues. Polymorphisms in COMT gene can attenuate COMT activity and increase sensitivity to pain. Human studies exploring the effect of COMT polymorphisms on pain sensitivity have mostly included small, heterogeneous samples and have ignored several important single nucleotide polymorphisms (SNPs). This study examines the effect of COMT polymorphisms on experimental and postoperative pain phenotypes in a large ethnically homogeneous female patient cohort. Methods Intensity of cold (+2–4°C) and heat (+48°C) pain and tolerance to cold pain were assessed in 1,000 patients scheduled for breast cancer surgery. Acute postoperative pain and oxycodone requirements were recorded. Twenty-two COMT SNPs were genotyped and their association with six pain phenotypes analyzed with linear regression. Results There was no association between any of the tested pain phenotypes and SNP rs4680. The strongest association signals were seen between rs165774 and heat pain intensity as well as rs887200 and cold pain intensity. In both cases, minor allele carriers reported less pain. Neither of these results remained significant after strict multiple testing corrections. When analyzed further, the effect of rs887200 was, however, shown to be significant and consistent throughout the cold pressure test. No evidence of association between the SNPs and postoperative oxycodone consumption was found. Conclusions SNPs rs887200 and rs165774 located in the untranslated regions of the gene had the strongest effects on pain sensitivity. Their effect on pain is described here for the first time. These results should be confirmed in further studies and the potential functional mechanisms of the variants studied. PMID:24343288

  8. Overlooked difference between hydrogen bonds of equal strength formed between catechol and an oxygen or nitrogen base. Experiments and DFT calculations.

    PubMed

    Foti, Mario C; DiLabio, Gino A; Ingold, K U

    2003-11-26

    The IR spectrum of catechol in CCl(4) shows two fairly sharp O-H stretching bands of roughly equal absorbance at 3615.0 and 3569.6 cm(-1) due, respectively, to the "free" OH and the intramolecularly H-bonded OH groups. Intermolecular H-bond formation between the "free" OH and a hydrogen bond acceptor (HBA) decreases its stretching frequency by several hundred wavenumbers and simultaneously decreases the frequency of the intramolecularly H-bonded OH by a few tens of wavenumbers. The magnitude of these frequency shifts, Deltaupsilon(inter) and Deltaupsilon(intra), respectively, are very well reproduced by DFT calculations. As would be expected, the magnitudes of Deltaupsilon(inter) and Deltaupsilon(intra) increase as the HB accepting ability of the HBA increases as quantified, on a relative scale, by the HBA's values (Abraham et al. J. Chem. Soc. Perkin Trans. 2 1990, 521). However, plots of experimental, or calculated, frequency shifts versus reveal that Deltaupsilon(inter) and Deltaupsilon(intra) are ca. 40% larger for a nitrogen atom HBA than for an oxygen atom HBA having equal HBA activity. We hypothesize that for HBAs of equal strength, i.e., of equal, the H-bond in (O-H- - -O)(inter) is shorter and, hence, intrinsically stronger than the H-bond in the (O-H- - -N)(inter). However, we further hypothesize that there is more charge separation in the H-bond to N because N is a better proton acceptor than O. Hence, it is the greater Coulombic attraction in (O-H- - -N)(inter) which strengthens this H-bond and compensates for its greater length. Theoretical calculations lend support to these hypotheses. PMID:14624616

  9. Meta-analysis reveals a lack of association between a common catechol-O-methyltransferase (COMT) polymorphism val158met and fibromyalgia

    PubMed Central

    Zhang, Lei; Zhu, Junwei; Chen, Yong; Zhao, Jianning

    2014-01-01

    This study is to evaluate the association between the catechol-O-methyltransferase (COMT) gene val158met polymorphism and FM risk. We performed a meta-analysis of 8 case-control studies that included 589 FM cases and 527 case-free controls. We assessed the strength of the association, using odds ratios (ORs) with 95% confidence intervals (CIs). Overall, this meta-analysis showed that the COMT gene val158met polymorphism was not associated with FM risk in all genetic models, i.e., allele (met vs. val: OR=1.46, 95% CI=0.80-2.66, P heterpgeneity<0.001), homozygous (met/met vs. val/val: OR=1.72, 95% CI=0.61-4.87, P heterpgeneity<0.001), heterozygous (val/met vs. val/val: OR=1.25, 95% CI=0.82-1.92, P heterpgeneity=0.050), recessive (met/met vs. val/val+val/met: OR=1.52, 95% CI=0.60-3.86, P heterpgeneity<0.001) and dominant model (met/met+val/met vs. val/val: OR=1.52, 95% CI=0.80-2.90, P heterpgeneity<0.001). Similarly, there were no significant associations in the subgroup analyses by ethnicity and HWE. No publication bias was found in the present study. This meta-analysis suggests that the COMT gene val158met polymorphism is not associated with FM risk. Further large and well-designed studies are needed to confirm this association. PMID:25674213

  10. Isolation and characterization of catechol 2,3-dioxygenase genes from phenanthrene degraders Sphingomonas, sp. ZP1 and Pseudomonas sp. ZP2.

    PubMed

    Zhao, He-Ping; Liang, Sheng-Hua; Yang, Xiaoe

    2011-12-01

    Two bacterial strains, Sphingomonas sp. ZP1 and Pseudomonas stutzeri sp ZP2, were identified as having phenanthrene-degrading ability and were characterized. The activity of catechol-2,3-dioxygenase (C230) of both strains was measured. With degradation of phenanthrene with an initial concentration of 250 ppm, the C230 activity of both strain ZP1 and ZP2 increased. The ZP1 strain consumed all phenanthrene at day 6, and strain ZP2 degraded 250 ppm of phenanthrene at around day 5; C230 activity in strain ZP1 reached its peak of 6.92 U at day 6, and C230 activity in strain ZP2 achieved 7.80 U as its peak at day 5. After all phenanthrene (250ppm) was consumed, C230 activity in both Sphingomonas sp. ZP1 and Pseudomonas stutzeri ZP2 decreased. Analysis of the C230 gene sequence indicated that gene PhnZP1 from strain ZP1 has close sequence similarity with the C230 gene from the nearest strain Sphingomonas. sp. KMG 425 (98% identity), 97% similarity with the C230 gene catA from S. paucimobilis sp. TZS-7, and 94% similar with catE gene from S. sp. HV3. The sequence of the C230 gene PhnZP2 of strain ZP2 has 98% similarity with the cmpE gene from strain S. sp., 92% similarity with the phnE gene from P. sp. DJ77 strain, and 90% similarity with all selected C230 genes from Pseudomonas genus strains.

  11. Estrogen metabolism and formation of estrogen-DNA adducts in estradiol-treated MCF-10F cells. The effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin induction and catechol-O-methyltransferase inhibition

    PubMed Central

    Lu, Fang; Zahid, Muhammad; Saeed, Muhammad; Cavalieri, Ercole L.; Rogan, Eleanor G.

    2007-01-01

    Formation of estrogen metabolites that react with DNA is thought to be a mechanism of cancer initiation by estrogens. The estrogens estrone (E1) and estradiol (E2) can form catechol estrogen (CE) metabolites, catechol estrogen quinones [E1(E2)-3,4-Q], which react with DNA to form predominantly depurinating adducts. This may lead to mutations that initiate cancer. Catechol-O-methyltransferase (COMT) catalyzes an inactivation (protective) pathway for CE. This study investigated the effect of inhibiting COMT activity on the levels of depurinating 4-OHE1(E2)-1-N3Ade and 4-OHE1(E2)-1-N7Gua adducts in human breast epithelial cells. MCF-10F cells were treated with TCDD, a cytochrome P450 inducer, then with E2 and Ro41−0960, a COMT inhibitor. Estrogen metabolites and depurinating DNA adducts in culture medium were analyzed by HPLC with electrochemical detection. Pretreatment of cells with TCDD increased E2 metabolism to 4-OHE1(E2) and 4-OCH3E1(E2). Inclusion of Ro41−0960 and E2 in the medium blocked formation of methoxyCE, and depurinating adducts were observed. With Ro41−0960, more adducts were detected in MCF-10F cells exposed to 1 μM E2, whereas without the inhibitor, no increases in adducts were detected with E2 ≤10 μM. We conclude that low COMT activity and increased formation of depurinating adducts can be critical factors leading to initiation of breast cancer. PMID:17582757

  12. Catechol oxidase-like oxidation chemistry of the 1-20 and 1-16 fragments of Alzheimer's disease-related beta-amyloid peptide: their structure-activity correlation and the fate of hydrogen peroxide.

    PubMed

    da Silva, Giordano F Z; Tay, William M; Ming, Li-June

    2005-04-29

    The Cu2+ complexes of the 1-16 and the 1-20 fragments of the Alzheimer's disease-related beta-amyloid peptide (CuAbeta) show significant oxidative activities toward a catechol-like substrate trihydroxylbenzene and plasmid DNA cleavage. The latter reflects possible oxidative stress to biological macromolecules, yielding supporting data to the pathological role of these soluble Abeta fragments. The former exhibits enzyme-like kinetics and is dependent on [H2O2], exhibiting k(cat) of 0.066 s-1 (6000-fold higher than the reaction without CuAbeta) and k(cat)/Km of 37.2 m-1s-1 under saturating [H2O2] of approximately 0.24%. This kinetic profile is consistent with metal-centered redox chemistry for the action of CuAbeta. A mechanism is proposed by the use of the catalytic cycle of dinuclear catechol oxidase as a working model. Trihydroxylbenzene is also oxidized by CuAbeta aerobically without H2O2, affording rate constants of 6.50x10(-3) s-1 and 3.25 m-1s-1. This activity is also consistent with catechol oxidase action in the absence of H2O2, wherein the substrate binds and reduces the Cu2+ center first, followed by O2 binding to afford the mu-eta2:eta2-peroxo intermediate, which oxidizes a second substrate to complete the catalytic cycle. A tetragonally distorted octahedral metal coordination sphere with three coordinated His side chains and some specific H-bonding interactions is concluded from the electronic spectrum of CuAbeta, hyperfine-shifted 1H NMR spectrum of CoAbeta, and molecular mechanics calculations. The results presented here are expected to add further insight into the chemistry of metallo-Abeta, which may assist better understanding of the neuropathology of Alzheimer's disease. PMID:15699049

  13. Chemical structure and biodegradability of halogenated aromatic compounds. Halogenated muconic acids as intermediates.

    PubMed Central

    Schmidt, E; Remberg, G; Knackmuss, H J

    1980-01-01

    Substituted muconic acids were prepared from the corresponding catechols by pyrocatechase II from Pseudomonas sp. B13. The stabilities of substituted muconic acids were compared under different pH conditions. 3-Substituted cis, cis-muconic acids cycloisomerized readily in slightly acidic solutions, whereas 2-chloro- and 2-fluoro-cis,cis-muconic acids were stable under these conditions and could be isolated as crystalline compounds. They were isomerized to the cis, trans-form in highly acidic solution (pH 1), particularly when heated to 80 degrees C. Cycloisomerization of 2-chloro-cis,cis-muconic acid in 75% (v/v) H2SO4 yields 4-carboxymethyl-2-chloro-but-2-en-4-olide (4-chloro-2,5-dihydro-5-oxo-3H-furan-2-ylacetic acid). THe cis,cis-configuration of 2-chloromuconic acid was certified by 1H n.m.r. spectroscopy and by enzymic cycloisomerization. Although the cis,cis-configuration of 2-fluoromuconic acid was confirmed by corresponding spectroscopic data, it was not cycloisomerized by crude extracts or cycloisomerase II preparations from Pseudomonas sp. B13. PMID:7305905

  14. Study on the kinetics and transformation products of salicylic acid in water via ozonation.

    PubMed

    Hu, Ruikang; Zhang, Lifeng; Hu, Jiangyong

    2016-06-01

    As salicylic acid is one of widely used pharmaceuticals, its residue has been found in various environmental water systems e.g. wastewater, surface water, treated water and drinking water. It has been reported that salicylic acid can be efficiently removed by advanced oxidation processes, but there are few studies on its transformation products and ozonation mechanisms during ozonation process. The objective of this study is to characterize the transformation products, investigate the degradation mechanisms at different pH, and propose the ozonation pathways of salicylic acid. The results showed that the rate of degradation was about 10 times higher at acidic condition than that at alkaline condition in the first 1 min when 1 mg L(-1) of ozone solution was added into 1 mg L(-1) of salicylic acid solution. It was proposed that ozone direct oxidation mechanism dominates at acidic condition, while indirect OH radical mechanism dominates at alkaline condition. A two stages pseudo-first order reaction was proposed at different pH conditions. Various hydroxylation products, carbonyl compounds and carboxylic acids, such as 2,5-dihydroxylbenzoic acid, 2,3-dihydroxylbenzoic acid, catechol, formaldehyde, glyoxal, acetaldehyde, maleic acid, acetic acid and oxalic acid etc. were identified as ozonation transformation products. In addition, acrylic acid was identified, for the first time, as ozonation transformation products through high resolution liquid chromatography-time of flight mass spectrometer. The information demonstrated in this study will help us to better understand the possible effects of ozonation products on the water quality. The degradation pathways of salicylic acid by ozonation in water sample were proposed. As both O3 and OH radical were important in the reactions, the degradation pathways of salicylic acid by ozonation in water sample were proposed at acidic and basic conditions. To our knowledge, there was no integrated study reported on the ozonation of

  15. Study on the kinetics and transformation products of salicylic acid in water via ozonation.

    PubMed

    Hu, Ruikang; Zhang, Lifeng; Hu, Jiangyong

    2016-06-01

    As salicylic acid is one of widely used pharmaceuticals, its residue has been found in various environmental water systems e.g. wastewater, surface water, treated water and drinking water. It has been reported that salicylic acid can be efficiently removed by advanced oxidation processes, but there are few studies on its transformation products and ozonation mechanisms during ozonation process. The objective of this study is to characterize the transformation products, investigate the degradation mechanisms at different pH, and propose the ozonation pathways of salicylic acid. The results showed that the rate of degradation was about 10 times higher at acidic condition than that at alkaline condition in the first 1 min when 1 mg L(-1) of ozone solution was added into 1 mg L(-1) of salicylic acid solution. It was proposed that ozone direct oxidation mechanism dominates at acidic condition, while indirect OH radical mechanism dominates at alkaline condition. A two stages pseudo-first order reaction was proposed at different pH conditions. Various hydroxylation products, carbonyl compounds and carboxylic acids, such as 2,5-dihydroxylbenzoic acid, 2,3-dihydroxylbenzoic acid, catechol, formaldehyde, glyoxal, acetaldehyde, maleic acid, acetic acid and oxalic acid etc. were identified as ozonation transformation products. In addition, acrylic acid was identified, for the first time, as ozonation transformation products through high resolution liquid chromatography-time of flight mass spectrometer. The information demonstrated in this study will help us to better understand the possible effects of ozonation products on the water quality. The degradation pathways of salicylic acid by ozonation in water sample were proposed. As both O3 and OH radical were important in the reactions, the degradation pathways of salicylic acid by ozonation in water sample were proposed at acidic and basic conditions. To our knowledge, there was no integrated study reported on the ozonation of

  16. Novel pathway for the degradation of 2-chloro-4-nitrobenzoic acid by Acinetobacter sp. strain RKJ12.

    PubMed

    Prakash, Dhan; Kumar, Ravi; Jain, R K; Tiwary, B N

    2011-09-01

    The organism Acinetobacter sp. RKJ12 is capable of utilizing 2-chloro-4-nitrobenzoic acid (2C4NBA) as a sole source of carbon, nitrogen, and energy. In the degradation of 2C4NBA by strain RKJ12, various metabolites were isolated and identified by a combination of chromatographic, spectroscopic, and enzymatic activities, revealing a novel assimilation pathway involving both oxidative and reductive catabolic mechanisms. The metabolism of 2C4NBA was initiated by oxidative ortho dehalogenation, leading to the formation of 2-hydroxy-4-nitrobenzoic acid (2H4NBA), which subsequently was metabolized into 2,4-dihydroxybenzoic acid (2,4-DHBA) by a mono-oxygenase with the concomitant release of chloride and nitrite ions. Stoichiometric analysis indicated the consumption of 1 mol O(2) per conversion of 2C4NBA to 2,4-DHBA, ruling out the possibility of two oxidative reactions. Experiments with labeled H(2)(18)O and (18)O(2) indicated the involvement of mono-oxygenase-catalyzed initial hydrolytic dechlorination and oxidative denitration mechanisms. The further degradation of 2,4-DHBA then proceeds via reductive dehydroxylation involving the formation of salicylic acid. In the lower pathway, the organism transformed salicylic acid into catechol, which was mineralized by the ortho ring cleavage catechol-1,2-dioxygenase to cis, cis-muconic acid, ultimately forming tricarboxylic acid cycle intermediates. Furthermore, the studies carried out on a 2C4NBA(-) derivative and a 2C4NBA(+) transconjugant demonstrated that the catabolic genes for the 2C4NBA degradation pathway possibly reside on the ∼55-kb transmissible plasmid present in RKJ12.

  17. Novel Pathway for the Degradation of 2-Chloro-4-Nitrobenzoic Acid by Acinetobacter sp. Strain RKJ12▿†

    PubMed Central

    Prakash, Dhan; Kumar, Ravi; Jain, R. K.; Tiwary, B. N.

    2011-01-01

    The organism Acinetobacter sp. RKJ12 is capable of utilizing 2-chloro-4-nitrobenzoic acid (2C4NBA) as a sole source of carbon, nitrogen, and energy. In the degradation of 2C4NBA by strain RKJ12, various metabolites were isolated and identified by a combination of chromatographic, spectroscopic, and enzymatic activities, revealing a novel assimilation pathway involving both oxidative and reductive catabolic mechanisms. The metabolism of 2C4NBA was initiated by oxidative ortho dehalogenation, leading to the formation of 2-hydroxy-4-nitrobenzoic acid (2H4NBA), which subsequently was metabolized into 2,4-dihydroxybenzoic acid (2,4-DHBA) by a mono-oxygenase with the concomitant release of chloride and nitrite ions. Stoichiometric analysis indicated the consumption of 1 mol O2 per conversion of 2C4NBA to 2,4-DHBA, ruling out the possibility of two oxidative reactions. Experiments with labeled H218O and 18O2 indicated the involvement of mono-oxygenase-catalyzed initial hydrolytic dechlorination and oxidative denitration mechanisms. The further degradation of 2,4-DHBA then proceeds via reductive dehydroxylation involving the formation of salicylic acid. In the lower pathway, the organism transformed salicylic acid into catechol, which was mineralized by the ortho ring cleavage catechol-1,2-dioxygenase to cis, cis-muconic acid, ultimately forming tricarboxylic acid cycle intermediates. Furthermore, the studies carried out on a 2C4NBA− derivative and a 2C4NBA+ transconjugant demonstrated that the catabolic genes for the 2C4NBA degradation pathway possibly reside on the ∼55-kb transmissible plasmid present in RKJ12. PMID:21803909

  18. In Silico Discovery and In Vitro Validation of Catechol-Containing Sulfonohydrazide Compounds as Potent Inhibitors of the Diguanylate Cyclase PleD

    PubMed Central

    Fernicola, Silvia; Paiardini, Alessandro; Giardina, Giorgio; Rampioni, Giordano; Leoni, Livia; Cutruzzolà, Francesca

    2015-01-01

    ABSTRACT Biofilm formation is responsible for increased antibiotic tolerance in pathogenic bacteria. Cyclic di-GMP (c-di-GMP) is a widely used second-messenger signal that plays a key role in bacterial biofilm formation. c-di-GMP is synthesized by diguanylate cyclases (DGCs), a conserved class of enzymes absent in mammals and hence considered attractive molecular targets for the development of antibiofilm agents. Here, the results of a virtual screening approach aimed at identifying small-molecule inhibitors of the DGC PleD from Caulobacter crescentus are described. A three-dimensional (3D) pharmacophore model, derived from the mode of binding of GTP to the active site of PleD, was exploited to screen the ZINC database of compounds. Seven virtual hits were tested in vitro for their ability to inhibit the activity of purified PleD by using circular dichroism spectroscopy. Two drug-like molecules with a catechol moiety and a sulfonohydrazide scaffold were shown to competitively inhibit PleD at the low-micromolar range (50% inhibitory concentration [IC50] of ∼11 μM). Their predicted binding mode highlighted key structural features presumably responsible for the efficient inhibition of PleD by both hits. These molecules represent the most potent in vitro inhibitors of PleD identified so far and could therefore result in useful leads for the development of novel classes of antimicrobials able to hamper biofilm formation. IMPORTANCE Biofilm-mediated infections are difficult to eradicate, posing a threatening health issue worldwide. The capability of bacteria to form biofilms is almost universally stimulated by the second messenger c-di-GMP. This evidence has boosted research in the last decade for the development of new antibiofilm strategies interfering with c-di-GMP metabolism. Here, two potent inhibitors of c-di-GMP synthesis have been identified in silico and characterized in vitro by using the well-characterized DGC enzyme PleD from C. crescentus as a structural

  19. Differential Effects of the Catechol-O-Methyltransferase Val158Met Genotype on the Cognitive Function of Schizophrenia Patients and Healthy Japanese Individuals

    PubMed Central

    Tsuchimine, Shoko; Yasui-Furukori, Norio; Kaneda, Ayako; Kaneko, Sunao

    2013-01-01

    Background The functional polymorphism Val158Met in the catechol-O-methyltransferase (COMT) gene has been associated with differences in prefrontal cognitive functions in patients with schizophrenia and healthy individuals. Several studies have indicated that the Met allele is associated with better performance on measures of cognitive function. We investigated whether the COMT Val158Met genotype was associated with cognitive function in 149 healthy controls and 118 patients with schizophrenia. Methods Cognitive function, including verbal memory, working memory, motor speed, attention, executive function and verbal fluency, was assessed by the Brief Assessment of Cognition in Schizophrenia (BACS-J). We employed a one-way analysis of variance (ANOVA) and a multiple regression analysis to determine the associations between the COMT Val158Met genotype and the BACS-J measurements. Results The one-way ANOVA revealed a significant difference in the scores on the Tower of London, a measure of executive function, between the different Val158Met genotypes in the healthy controls (p = 0.023), and a post-hoc analysis showed significant differences between the scores on the Tower of London in the val/val genotype group (18.6 ± 2.4) compared to the other two groups (17.6 ± 2.7 for val/met and 17.1 ± 3.2 for met/met; p = 0.027 and p = 0.024, respectively). Multiple regression analyses revealed that executive function was significantly correlated with the Val158Met genotype (p = 0.003). However, no evidence was found for an effect of the COMT on any cognitive domains of the BACS-J in the patients with schizophrenia. Conclusion These data support the hypothesis that the COMT Val158Met genotype maintains an optimal level of dopamine activity. Further studies should be performed that include a larger sample size and include patients on and off medication, as these patients would help to confirm our findings. PMID:24282499

  20. Catechol-O-Methyltransferase Val158Met Polymorphism and Clinical Response to Antipsychotic Treatment in Schizophrenia and Schizo-Affective Disorder Patients: a Meta-Analysis

    PubMed Central

    Huang, Eric; Zai, Clement C.; Lisoway, Amanda; Maciukiewicz, Malgorzata; Felsky, Daniel; Tiwari, Arun K.; Bishop, Jeffrey R.; Ikeda, Masashi; Molero, Patricio; Ortuno, Felipe; Porcelli, Stefano; Samochowiec, Jerzy; Mierzejewski, Pawel; Gao, Shugui; Crespo-Facorro, Benedicto; Pelayo-Terán, José M; Kaur, Harpreet; Kukreti, Ritushree; Meltzer, Herbert Y.; Lieberman, Jeffrey A.; Potkin, Steven G.; Müller, Daniel J.

    2016-01-01

    Background: The catechol-O-methyltransferase (COMT) enzyme plays a crucial role in dopamine degradation, and the COMT Val158Met polymorphism (rs4680) is associated with significant differences in enzymatic activity and consequently dopamine concentrations in the prefrontal cortex. Multiple studies have analyzed the COMT Val158Met variant in relation to antipsychotic response. Here, we conducted a meta-analysis examining the relationship between COMT Val158Met and antipsychotic response. Methods: Searches using PubMed, Web of Science, and PsycInfo databases (03/01/2015) yielded 23 studies investigating COMT Val158Met variation and antipsychotic response in schizophrenia and schizo-affective disorder. Responders/nonresponders were defined using each study’s original criteria. If no binary response definition was used, authors were asked to define response according to at least 30% Positive and Negative Syndrome Scale score reduction (or equivalent in other scales). Analysis was conducted under a fixed-effects model. Results: Ten studies met inclusion criteria for the meta-analysis. Five additional antipsychotic-treated samples were analyzed for Val158Met and response and included in the meta-analysis (ntotal=1416). Met/Met individuals were significantly more likely to respond than Val-carriers (P=.039, ORMet/Met=1.37, 95% CI: 1.02–1.85). Met/Met patients also experienced significantly greater improvement in positive symptoms relative to Val-carriers (P=.030, SMD=0.24, 95% CI: 0.024–0.46). Posthoc analyses on patients treated with atypical antipsychotics (n=1207) showed that Met/Met patients were significantly more likely to respond relative to Val-carriers (P=.0098, ORMet/Met=1.54, 95% CI: 1.11–2.14), while no difference was observed for typical-antipsychotic-treated patients (n=155) (P=.65). Conclusions: Our findings suggest that the COMT Val158Met polymorphism is associated with response to antipsychotics in schizophrenia and schizo-affective disorder

  1. Relation between the catalytic efficiency of the synthetic analogues of catechol oxidase with their electrochemical property in the free state and substrate-bound state.

    PubMed

    Chakraborty, Prateeti; Adhikary, Jaydeep; Ghosh, Bipinbihari; Sanyal, Ria; Chattopadhyay, Shyamal Kumar; Bauzá, Antonio; Frontera, Antonio; Zangrando, Ennio; Das, Debasis

    2014-08-18

    A library of 15 dicopper complexes as synthetic analogues of catechol oxidase has been synthesized with the aim to determine the relationship between the electrochemical behavior of the dicopper(II) species in the absence as well as in the presence of 3,5-di-tert-butylcatechol (3,5-DTBC) as model substrate and the catalytic activity, kcat, in DMSO medium. The complexes have been characterized by routine physicochemical techniques as well as by X-ray single-crystal structure analysis in some cases. Fifteen "end-off" compartmental ligands have been designed as 1 + 2 Schiff-base condensation product of 2,6-diformyl-4-R-phenol (R = Me, (t)Bu, and Cl) and five different amines, N-(2-aminoethyl)piperazine, N-(2-aminoethyl)pyrrolidine, N-(2-aminoethyl)morpholine, N-(3-aminopropyl)morpholine, and N-(2-aminoethyl)piperidine. Interestingly, in case of the combination of 2,6-diformyl-4-methylphenol and N-(2-aminoethyl)morpholine/N-(3-aminopropyl)morpholine/N-(2-aminoethyl)piperidine 1 + 1 condensation becomes the reality and the ligands are denoted as L2(1-3). On reaction of copper(II) nitrate with L2(1-3) in situ complexes 3, 12, and 13 are formed having general formula Cu2(L2(1-3))2(NO3)2. The remaining 12 ligands obtained as 1 + 2 condensation products are denoted as L1(1-12), which produce complexes having general formula Cu2(L1(1-12))(NO3)2. Catecholase activity of all 15 complexes has been investigated in DMSO medium using 3,5-DTBC as model substrate. Treatment on the basis of Michaelis-Menten model has been applied for kinetic study, and thereby turnover number, kcat, values have been evaluated. Cyclic voltametric (CV) and differential pulse voltametric (DPV) studies of the complexes in the presence as well as in the absence of 3,5-DTBC have been thoroughly investigated in DMSO medium. From those studies it is evident that oxidation of 3,5-DTBC catalyzed by dicopper(II) complexes proceed via two steps: first, semibenzoquinone followed by benzoquinone with concomitant

  2. Reaction between alkyl isocyanides and isopropylidene Meldrum's acid in the presence of bidentate nucleophiles.

    PubMed

    Yavari, Issa; Sabbaghan, Maryam; Hossaini, Zinatossadat

    2007-02-01

    The reaction between alkyl isocyanides and isopropylidene Meldrum's acid in the presence of 1,2-ethanediol leads to N (1)-(alkyl)-2-(5,7-dioxo-1,4-dioxepane-6-yl)-2-methylpropanamides. 1,3-Propanediol or 1,4-butanediol produce hydroxyalkyl 1-(tert-butyl)-4,4-dimethyl-2,5-dioxo-3-pyrrolidinecarboxylates. When the reaction was performed in the presence of catechol, bis(2-hydroxyphenyl) 2-[2-(tert-butylamino)-1,1-dimethyl-2-oxoethyl]malonate was obtained. 2-Aminophenols react with alkyl isocyanides in the presence of isopropylidene Meldrum's acid to produce 1-alkyl-N (3)-(2-hydroxyaryl)-4,4-dimethyl-2,5-dioxo-3-pyrrolidinecarboxamides in good yields.

  3. Heterogeneous conversion of NO2 on secondary organic aerosol surfaces: A possible source of nitrous acid (HONO) in the atmosphere?

    NASA Astrophysics Data System (ADS)

    Bröske, R.; Kleffmann, J.; Wiesen, P.

    2003-05-01

    The heterogeneous conversion of NO2 on different secondary organic aerosols (SOA) was investigated with the focus on a possible formation of nitrous acid (HONO). In one set of experiments different organic aerosols were produced in the reactions of O3 with alpha-pinene, limonene or catechol and OH radicals with toluene or limonene, respectively. The aerosols were sampled on filters and exposed to humidified NO2 mixtures under atmospheric conditions. The estimated upper limits for the uptake coefficients of NO2 and the reactive uptake coefficients NO2 -> HONO are in the range of 10-6 and 10-7, respectively. The integrated HONO formation for 1 h reaction time was <1013 cm-2 geometrical surface and <1017 g-1 particle mass. In a second set of experiments the conversion of NO2 into HONO in the presence of organic particles was carried out in an aerosol flow tube under atmospheric conditions. In this case the aerosols were produced in the reaction of O3 with beta-pinene, limonene or catechol, respectively. The upper limits for the reactive uptake coefficients NO2 -> HONO were in the range of 7 x 10-7 - 9 x 10-6. The results from the present study show that heterogeneous formation of nitrous acid on secondary organic aerosols (SOA) is unimportant for the atmosphere.

  4. Heterogeneous conversion of NO2 on secondary organic aerosol surfaces: A possible source of nitrous acid (HONO) in the atmosphere?

    NASA Astrophysics Data System (ADS)

    Bröske, R.; Kleffmann, J.; Wiesen, P.

    2003-02-01

    The heterogeneous conversion of NO2 on different secondary organic aerosols (SOA) was investigated with the focus on a possible formation of nitrous acid (HONO). In one set of experiments different organic aerosols were produced in the reactions of O3 with α-pinene, limonene or catechol and OH radicals with toluene or limonene, respectively. The aerosols were sampled on filters and exposed to humidified NO2 mixtures under atmospheric conditions. The estimated upper limits for the uptake coefficients of NO2 and the reactive uptake coefficients NO2 →HONO are in the range of 10-6 and 10-7, respectively. The integrated HONO formation for 1 h reaction time was <1013 cm-2 geometrical surface and <1017 g-1 particle mass. In a second set of experiments the conversion of NO2 into HONO in the presence of organic particles was carried out in an aerosol flow tube under atmospheric conditions. In this case the aerosols were produced in the reaction of O3 with β-pinene, limonene or catechol, respectively. The upper limits for the reactive uptake coefficients NO2 → HONO were in the range of 7×10-7 -9×10-6. The results from the present study show that heterogeneous formation of nitrous acid on secondary organic aerosols (SOA) is unimportant for the atmosphere.

  5. Folic Acid

    MedlinePlus

    Folic acid is a B vitamin. It helps the body make healthy new cells. Everyone needs folic acid. For women who may get pregnant, it is really important. Getting enough folic acid before and during pregnancy can prevent major birth ...

  6. Folic Acid

    MedlinePlus

    Folic acid is used to treat or prevent folic acid deficiency. It is a B-complex vitamin needed by ... Folic acid comes in tablets. It usually is taken once a day. Follow the directions on your prescription label ...

  7. Amino acids

    MedlinePlus

    ... amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan , and valine. Nonessential amino acids "Nonessential" means that our bodies produce an amino ...

  8. Siderocalin/Lcn2/NGAL/24p3 Does Not Drive Apoptosis Through Gentisic Acid Mediated Iron Withdrawal in Hematopoietic Cell Lines

    PubMed Central

    Bandaranayake, Ashok D.; Ruiz, Mario; Rahmanto, Yohan Suryo; Kovačević, Žaklina; Clifton, Matthew C.; Holmes, Margaret A.; Kaiser, Brett K.; Barasch, Jonathan; Raymond, Kenneth N.; Richardson, Des R.; Strong, Roland K.

    2012-01-01

    Siderocalin (also lipocalin 2, NGAL or 24p3) binds iron as complexes with specific siderophores, which are low molecular weight, ferric ion-specific chelators. In innate immunity, siderocalin slows the growth of infecting bacteria by sequestering bacterial ferric siderophores. Siderocalin also binds simple catechols, which can serve as siderophores in the damaged urinary tract. Siderocalin has also been proposed to alter cellular iron trafficking, for instance, driving apoptosis through iron efflux via BOCT. An endogenous siderophore composed of gentisic acid (2,5-dihydroxybenzoic acid) substituents was proposed to mediate cellular efflux. However, binding studies reported herein contradict the proposal that gentisic acid forms high-affinity ternary complexes with siderocalin and iron, or that gentisic acid can serve as an endogenous siderophore at neutral pH. We also demonstrate that siderocalin does not induce cellular iron efflux or stimulate apoptosis, questioning the role siderocalin plays in modulating iron metabolism. PMID:22928018

  9. Acid Rain.

    ERIC Educational Resources Information Center

    Openshaw, Peter

    1987-01-01

    Provides some background information on acid deposition. Includes a historical perspective, describes some effects of acid precipitation, and discusses acid rain in the United Kingdom. Contains several experiments that deal with the effects of acid rain on water quality and soil. (TW)

  10. Synthesis, crystal structure, spectral studies, and catechol oxidase activity of trigonal bipyramidal Cu(II) complexes derived from a tetradentate diamide bisbenzimidazole ligand.

    PubMed

    Gupta, M; Mathur, P; Butcher, R J

    2001-02-26

    . Palaniandavar, M.; Pandiyan, T.; Laxminarayan, M.; Manohar, H. J. Chem. Soc., Dalton Trans. 1995, 457. Sakurai, T.; Oi, H.; Nakahara, A. Inorg. Chim. Acta 1984, 92, 131). It is therefore concluded that binding of amide carbonyl oxygen destabilizes the Cu(II) state. The complex [Cu(II)(GBHA)(NO(3))](NO(3)) could be successfully reduced by the addition of dihydroxybenzenes to the corresponding [Cu(I)(GBHA)](NO(3)). (1)H NMR of the reduced complex shows slightly broadened and shifted (1)H signals. The reduction of the Cu(II) complex presumably occurs with the corresponding 2e(-) oxidation of the quinol to quinone. Such a conversion is reminiscent of the functioning of a copper-containing catechol oxidase from sweet potatoes and the met form of the enzyme tyrosinase. PMID:11258993

  11. Synthesis, crystal structure, spectral studies, and catechol oxidase activity of trigonal bipyramidal Cu(II) complexes derived from a tetradentate diamide bisbenzimidazole ligand.

    PubMed

    Gupta, M; Mathur, P; Butcher, R J

    2001-02-26

    . Palaniandavar, M.; Pandiyan, T.; Laxminarayan, M.; Manohar, H. J. Chem. Soc., Dalton Trans. 1995, 457. Sakurai, T.; Oi, H.; Nakahara, A. Inorg. Chim. Acta 1984, 92, 131). It is therefore concluded that binding of amide carbonyl oxygen destabilizes the Cu(II) state. The complex [Cu(II)(GBHA)(NO(3))](NO(3)) could be successfully reduced by the addition of dihydroxybenzenes to the corresponding [Cu(I)(GBHA)](NO(3)). (1)H NMR of the reduced complex shows slightly broadened and shifted (1)H signals. The reduction of the Cu(II) complex presumably occurs with the corresponding 2e(-) oxidation of the quinol to quinone. Such a conversion is reminiscent of the functioning of a copper-containing catechol oxidase from sweet potatoes and the met form of the enzyme tyrosinase.

  12. Acid rain

    SciTech Connect

    Not Available

    1985-01-01

    This report has four parts: they discuss acid rain in relation to acid soils, agriculture, forests, and aquatic ecosystems. Among findings: modern sources of acid deposition from the atmosphere for all the acid soils in the world, nor even chiefly responsible for those of northern U.S. Agriculture has its problems, but acid precipitation is probably not one of them. More research is needed to determine to what extent acid precipitation is responsible for forest declines and for smaller detrimental effects on forest growth where no damage to the foliage is evident. Many lakes and streams are extremely sensitive to added acids.

  13. Conformational preferences of 3,4-dihydroxyphenylacetic acid (DOPAC)

    NASA Astrophysics Data System (ADS)

    Lopes Jesus, A. J.; Jarmelo, S.; Fausto, R.; Reva, I.

    2015-04-01

    The conformational space of 3,4-dihydroxyphenylacetic acid (DOPAC), an important dopamine metabolite, has been investigated by quantum chemical methods (B3LYP and MP2, with the 6-311++G(d,p) basis set) and matrix-isolation infrared spectroscopy. Detailed analysis of the calculated potential energy surfaces of the molecule led to identification of thirteen unique conformers, all of them showing the acetic acid side chain out of the aromatic ring plane by 60-95°. According to the calculated Gibbs energies, the five lowest energy conformers make up 99.7% of the conformational mixture at 298.15 K, exhibiting individual populations falling between 16% and 24%. The main conformational trends of this molecule were interpreted on the grounds of a thorough analysis of the structural parameters and by the application of the Natural Bond Orbital theory. The role of the intramolecular interactions on the relative stability and structure of the conformers was also investigated. The infrared spectrum of DOPAC was registered after isolation of its monomers in argon and xenon matrices. Only one of DOPAC forms populated in the gas phase could be trapped in both matrix gases. This result is in agreement with the predicted low energy barriers for conformational isomerization and is also supported by annealing experiments. The spectra of matrix-isolated model compounds, phenylacetic acid and catechol, were studied under the same experimental conditions. These data were used as references and assisted in the interpretation of the results obtained for DOPAC.

  14. Genetic Variation in the Catechol-O-Methyl Transferase Val108/158Met Is Linked to the Caudate and Posterior Cingulate Cortex Volume in Healthy Subjects: Voxel-Based Morphometry Analysis of Brain Magnetic Resonance Imaging.

    PubMed

    Watanabe, Keita; Kakeda, Shingo; Yoshimura, Reiji; Ide, Satoru; Hayashi, Kenji; Katsuki, Asuka; Umene-Nakano, Wakako; Watanabe, Rieko; Abe, Osamu; Korogi, Yukunori

    2015-01-01

    The effect of the catechol-O-methyltransferase (COMT) Val158Met polymorphism on brain morphology has been investigated but remains controversial. We hypothesized that a comparison between Val/Val and Val/Met individuals, which may represent the most different combinations concerning the effects of the COMT genotype, may reveal new findings. We investigated the brain morphology using 3-Tesla magnetic resonance imaging in 27 Val/Val and 22 Val/Met individuals. Voxel-based morphometry revealed that the volumes of the bilateral caudate and posterior cingulate cortex were significantly smaller in Val/Val individuals than in Val/Met individuals [right caudate: false discovery rate (FDR)-corrected p = 0.048; left caudate: FDR-corrected p = 0.048; and bilateral posterior cingulate cortex: FDR-corrected p = 0.048]. This study demonstrates that interacting functional variants of COMT affect gray matter regional volumes in healthy subjects.

  15. Impact of deformation energy on the hydrogen bonding interactions in gas phase 3-X catechol ⋯ H2O complexes (X = H, F, Cl, Br): The effect of approach of a water molecule

    NASA Astrophysics Data System (ADS)

    Deb, Debojit Kumar; Sarkar, Biplab

    2016-06-01

    The conformations and nature of hydrogen bonding interactions for 3-X catechol ⋯ H2O (X = H, F, Cl, Br) has been investigated by ab initio MP2, CCSD(T), and density functional B3LYP, wB97XD and M06-2X methods. The changes in interaction energies due to deformation of the structures has been studied in detail. The intra- and intermolecular hydrogen bonding interactions due to the different direction of approach of water molecule have been discussed. A detailed natural bond orbital (NBO) analysis and the symmetry-adapted perturbation theory (SAPT) based energy decomposition analysis has been carried out to elucidate interaction strength and properties in these hydrogen bonded systems. The charge transfer percentage (CTP) has been derived which will be universally useful for correlating binding energy, deformation energy and the geometrical parameters such as angles, bond lengths, etc. for other systems as well.

  16. Genetic Variation in the Catechol-O-Methyl Transferase Val108/158Met Is Linked to the Caudate and Posterior Cingulate Cortex Volume in Healthy Subjects: Voxel-Based Morphometry Analysis of Brain Magnetic Resonance Imaging

    PubMed Central

    Watanabe, Keita; Kakeda, Shingo; Yoshimura, Reiji; Ide, Satoru; Hayashi, Kenji; Katsuki, Asuka; Umene-Nakano, Wakako; Watanabe, Rieko; Abe, Osamu; Korogi, Yukunori

    2015-01-01

    The effect of the catechol-O-methyltransferase (COMT) Val158Met polymorphism on brain morphology has been investigated but remains controversial. We hypothesized that a comparison between Val/Val and Val/Met individuals, which may represent the most different combinations concerning the effects of the COMT genotype, may reveal new findings. We investigated the brain morphology using 3-Tesla magnetic resonance imaging in 27 Val/Val and 22 Val/Met individuals. Voxel-based morphometry revealed that the volumes of the bilateral caudate and posterior cingulate cortex were significantly smaller in Val/Val individuals than in Val/Met individuals [right caudate: false discovery rate (FDR)-corrected p = 0.048; left caudate: FDR-corrected p = 0.048; and bilateral posterior cingulate cortex: FDR-corrected p = 0.048]. This study demonstrates that interacting functional variants of COMT affect gray matter regional volumes in healthy subjects. PMID:26566126

  17. Measurements of gas-phase inorganic and organic acids from biomass fires by negative-ion proton-transfer chemical-ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Veres, Patrick; Roberts, James M.; Burling, Ian R.; Warneke, Carsten; de Gouw, Joost; Yokelson, Robert J.

    2010-12-01

    Emissions from 34 laboratory biomass fires were investigated at the combustion facility of the U.S. Department of Agriculture Fire Sciences Laboratory in Missoula, Montana. Gas-phase organic and inorganic acids were quantified using negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS), open-path Fourier transform infrared spectroscopy (OP-FTIR), and proton-transfer-reaction mass spectrometry (PTR-MS). NI-PT-CIMS is a novel technique that measures the mass-to-charge ratio (m/z) of ions generated from reactions of acetate (CH3C(O)O-) ions with inorganic and organic acids. The emission ratios for various important reactive acids with respect to CO were determined. Emission ratios for isocyanic acid (HNCO), 1,2 and 1,3-benzenediols (catechol, resorcinol), nitrous acid (HONO), acrylic acid, methacrylic acid, propionic acid, formic acid, pyruvic acid, and glycolic acid were measured from biomass burning. Our measurements show that there is a significant amount of HONO in fresh smoke. The NI-PT-CIMS measurements were validated by comparison with OP-FTIR measurements of HONO and formic acid (HCOOH) and with PTR-MS measurements of HCOOH.

  18. Phenolic acid allelochemicals induced morphological, ultrastructural, and cytological modification on Cassia sophera L. and Allium cepa L.

    PubMed

    Gulzar, Aasifa; Siddiqui, M B; Bi, Shazia

    2016-09-01

    The allelopathic potential of leaf aqueous extract (LAE) of Calotropis procera on growth behavior, ultrastructural changes on Cassia sophera L., and cytological changes on Allium cepa L. was investigated. LAE at different concentrations (0.5, 1, 2, and 4 %) significantly reduced the root length, shoot length, and dry biomass of C. sophera. Besides, the ultrastructural changes (through scanning electron microscopy, SEM) induced in epidermal cells of 15-day-old seedlings of Cassia leaf were also noticed. The changes induced were shrinking and contraction of epidermal cells along with the formation of major grooves, canals, and cyst-like structures. The treated samples of epidermal cells no longer seem to be smooth as compared to control. LAE at different concentrations induces chromosomal aberrations and variation in shape of the interphase and prophase nucleus in A. cepa root tip cells when compared with control groups. The mitotic index in treated onion root tips decreased with increasing concentrations of the extracts. The most frequent aberrations were despiralization at prophase with the formation of micronuclei, sticky anaphase with bridges, sticky telophase, C-metaphase, etc. The results also show the induction of ghost cells, cells with membrane damage, and cells with heterochromatic nuclei by extract treatment. Upon HPLC analysis, nine phenolic acids (caffeic acid, gentisic acid, catechol, gallic acid, syringic acid, ellagic acid, resorcinol, p-coumaric acid, and p-hydroxy benzoic acid) were identified. Thus, the phenolic acids are mainly responsible for the allelopathic behavior of C. procera. PMID:26387115

  19. Fermentation products of solvent tolerant marine bacterium Moraxella spp. MB1 and its biotechnological applications in salicylic acid bioconversion.

    PubMed

    Wahidullah, Solimabi; Naik, Deepak N; Devi, Prabha

    2013-01-01

    As part of a proactive approach to environmental protection, emerging issues with potential impact on the environment is the subject of ongoing investigation. One emerging area of environmental research concerns pharmaceuticals like salicylic acid, which is the main metabolite of various analgesics including aspirin. It is a common component of sewage effluent and also an intermediate in the degradation pathway of various aromatic compounds which are introduced in the marine environment as pollutants. In this study, biotransformation products of salicylic acid by seaweed, Bryopsis plumosa, associated marine bacterium, Moraxella spp. MB1, have been investigated. Phenol, conjugates of phenol and hydroxy cinnamic acid derivatives (coumaroyl, caffeoyl, feruloyl and trihydroxy cinnamyl) with salicylic acid (3-8) were identified as the bioconversion products by electrospray ionization mass spectrometry. These results show that the microorganism do not degrade phenolic acid but catalyses oxygen dependent transformations without ring cleavage. The degradation of salicylic acid is known to proceed either via gentisic acid pathway or catechol pathway but this is the first report of biotransformation of salicylic acid into cinnamates, without ring cleavage. Besides cinnamic acid derivatives (9-12), metabolites produced by the bacterium include antimicrobial indole (13) and β-carbolines, norharman (14), harman (15) and methyl derivative (16), which are beneficial to the host and the environment. PMID:24391802

  20. Fermentation products of solvent tolerant marine bacterium Moraxella spp. MB1 and its biotechnological applications in salicylic acid bioconversion.

    PubMed

    Wahidullah, Solimabi; Naik, Deepak N; Devi, Prabha

    2013-01-01

    As part of a proactive approach to environmental protection, emerging issues with potential impact on the environment is the subject of ongoing investigation. One emerging area of environmental research concerns pharmaceuticals like salicylic acid, which is the main metabolite of various analgesics including aspirin. It is a common component of sewage effluent and also an intermediate in the degradation pathway of various aromatic compounds which are introduced in the marine environment as pollutants. In this study, biotransformation products of salicylic acid by seaweed, Bryopsis plumosa, associated marine bacterium, Moraxella spp. MB1, have been investigated. Phenol, conjugates of phenol and hydroxy cinnamic acid derivatives (coumaroyl, caffeoyl, feruloyl and trihydroxy cinnamyl) with salicylic acid (3-8) were identified as the bioconversion products by electrospray ionization mass spectrometry. These results show that the microorganism do not degrade phenolic acid but catalyses oxygen dependent transformations without ring cleavage. The degradation of salicylic acid is known to proceed either via gentisic acid pathway or catechol pathway but this is the first report of biotransformation of salicylic acid into cinnamates, without ring cleavage. Besides cinnamic acid derivatives (9-12), metabolites produced by the bacterium include antimicrobial indole (13) and β-carbolines, norharman (14), harman (15) and methyl derivative (16), which are beneficial to the host and the environment.

  1. Fermentation Products of Solvent Tolerant Marine Bacterium Moraxella spp. MB1 and Its Biotechnological Applications in Salicylic Acid Bioconversion

    PubMed Central

    Wahidullah, Solimabi; Naik, Deepak N.; Devi, Prabha

    2013-01-01

    As part of a proactive approach to environmental protection, emerging issues with potential impact on the environment is the subject of ongoing investigation. One emerging area of environmental research concerns pharmaceuticals like salicylic acid, which is the main metabolite of various analgesics including aspirin. It is a common component of sewage effluent and also an intermediate in the degradation pathway of various aromatic compounds which are introduced in the marine environment as pollutants. In this study, biotransformation products of salicylic acid by seaweed, Bryopsis plumosa, associated marine bacterium, Moraxella spp. MB1, have been investigated. Phenol, conjugates of phenol and hydroxy cinnamic acid derivatives (coumaroyl, caffeoyl, feruloyl and trihydroxy cinnamyl) with salicylic acid (3–8) were identified as the bioconversion products by electrospray ionization mass spectrometry. These results show that the microorganism do not degrade phenolic acid but catalyses oxygen dependent transformations without ring cleavage. The degradation of salicylic acid is known to proceed either via gentisic acid pathway or catechol pathway but this is the first report of biotransformation of salicylic acid into cinnamates, without ring cleavage. Besides cinnamic acid derivatives (9–12), metabolites produced by the bacterium include antimicrobial indole (13) and β-carbolines, norharman (14), harman (15) and methyl derivative (16), which are beneficial to the host and the environment. PMID:24391802

  2. Catechol estrogen formation by brain tissue: characterization of a direct product isolation assay for estrogen-2- and 4-hydroxylase activity and its application to studies of 2- and 4-hydroxyestradiol formation by rabbit hypothalamus

    SciTech Connect

    Hersey, R.M.; Williams, K.I.; Weisz, J.

    1981-12-01

    A direct product isolation assay for quantifying the formation of 2- and 4-hydroxyestradiol (2-OHE2 and 4-OHE2) from (6,7-3H)estradiol by rabbit hypothalami in vitro was developed, and the assay was used to characterize some properties of estrogen-2- and 4-hydroxylase activity in this tissue. The reaction was carried out under conditions that minimized further metabolism of enzymatically formed catechol estrogens. A simple two-step separation procedure, involving the use of a neutral alumina column, followed by thin layer chromatography, was developed to isolate the enzymatically formed catechol estrogens in a radiochemically homogeneous form. The detergent, Tween-80, was found to activate the enzyme and was used routinely at a concentration of 0.1% in the assay. The formation of 2-OHE2 was linear up to 10 min and with increasing protein concentrations up to 150 micrograms/incubation. Similar values were obtained for 4-OHE2. Maximum velocities (Vmax) for the formation of 2- and 4-OHE2 were 190 and 270 pmol/mg protein . 10 min, respectively. The apparent Km values with respect to estradiol for 2-OHE2 and 4-OHE2 were 125 and 150 microM, respectively. The highest specific activity for the enzyme was present in the 100,000 X g supernatant (S3), while the activity in the microsomal fraction (P3) was less than that in the original homogenate. Enzyme activity depended on the presence of NADPH and oxygen and was inhibited by CO as well as by high concentrations of SKF-525A. Estrogen-2- and 4-hydroxylase activity in rabbit hypothalamus differed from that in rat liver in two respects. In the liver, enzyme activity was localized in the microsomal fraction and was virtually abolished by Tween-80. In contrast, enzyme activity in rabbit hypothalamus was maximal in the soluble fraction (100,000 X g supernatant)and was stimulated by the detergent.

  3. Synthesis and antiproliferative activity of two diastereomeric lignan amides serving as dimeric caffeic acid-l-DOPA hybrids.

    PubMed

    Magoulas, George E; Rigopoulos, Andreas; Piperigkou, Zoi; Gialeli, Chrysostomi; Karamanos, Nikos K; Takis, Panteleimon G; Troganis, Anastassios N; Chrissanthopoulos, Athanassios; Maroulis, George; Papaioannou, Dionissios

    2016-06-01

    Two new diastereomeric lignan amides (4 and 5) serving as dimeric caffeic acid-l-DOPA hybrids were synthesized. The synthesis involved the FeCl3-mediated phenol oxidative coupling of methyl caffeate to afford trans-diester 1a as a mixture of enantiomers, protection of the catechol units, regioselective saponification, coupling with a suitably protected l-DOPA derivative, separation of the two diastereomers thus obtained by flash column chromatography and finally global chemoselective deprotection of the catechol units. The effect of hybrids 4 and 5 and related compounds on the proliferation of two breast cancer cell lines with different metastatic potential and estrogen receptor status (MDA-MB-231 and MCF-7) and of one epithelial lung cancer cell line, namely A-549, was evaluated for concentrations ranging from 1 to 256μM and periods of treatment of 24, 48 and 72h. Both hybrids showed interesting and almost equipotent antiproliferative activities (IC50 64-70μM) for the MDA-MB-231 cell line after 24-48h of treatment, but they were more selective and much more potent (IC50 4-16μM) for the MCF-7 cells after 48h of treatment. The highest activity for both hybrids and both breast cancer lines was observed after 72h of treatment (IC50 1-2μM), probably as the result of slow hydrolysis of their methyl ester functions. PMID:27155809

  4. Aminocaproic Acid

    MedlinePlus

    Aminocaproic acid is used to control bleeding that occurs when blood clots are broken down too quickly. This type ... the baby is ready to be born). Aminocaproic acid is also used to control bleeding in the ...

  5. Ethacrynic Acid

    MedlinePlus

    Ethacrynic acid, a 'water pill,' is used to treat swelling and fluid retention caused by various medical problems. It ... Ethacrynic acid comes as a tablet to take by mouth. It is usually taken once or twice a day ...

  6. Aristolochic Acids

    MedlinePlus

    ... Sciences NIH-HHS www.niehs.nih.gov Aristolochic Acids Key Points Report on Carcinogens Status Known to be human carcinogens Aristolochia Clematitis Aristolochic Acids n Known human carcinogens n Found in certain ...

  7. Obeticholic Acid

    MedlinePlus

    Obeticholic acid is used alone or in combination with ursodiol (Actigall, Urso) to treat primary biliary cholangitis (PBC; a ... were not treated successfully with ursodiol alone. Obeticholic acid is in a class of medications called farnesoid ...

  8. Acid mucopolysaccharides

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003368.htm Acid mucopolysaccharides To use the sharing features on this page, please enable JavaScript. Acid mucopolysaccharides is a test that measures the amount ...

  9. Fatty acids - trans fatty acids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The data supporting a negative effect of dietary trans fatty acids on cardiovascular disease risk is consistent. The primary dietary sources of trans fatty acids include partially hydrogenated fat and rudiment fat. The adverse effect of trans fatty acids on plasma lipoprotein profiles is consisten...

  10. Aspartic acid

    MedlinePlus

    ... Hormone production and release Normal nervous system function Plant sources of aspartic acid include: Legumes such as soybeans, garbanzo beans, and lentils Peanuts, almonds, walnuts, and flaxseeds Animal ...

  11. Synthesis, electrochemistry, and spectroscopic properties of six-coordinate monooxomolybdenum(VI) complexes containing tridentate Schiff base and bidentate catecholate ligands. Crystal and molecular structure of (N-salicylidene-2-aminophenolato)(naphthalene-2,3-diolato)oxomolybdenum(VI)

    SciTech Connect

    Mondal, J.U.; Schultz, F.A.; Brennan, T.D.; Scheidt, W.R.

    1988-11-02

    Six-coordinate monooxomolybdenum(VI) complexes, MoO(cat)(Sap), where Sap/sup 2 -/ = the Schiff base dianion N-salicylidene-2-aminophenolate and cat/sup 2 -/ = catecholate Cat/sup 2 -/, naphthalene-2,3-diolate (Naphcat/sup 2 -/), or 3,5-di-tert-butylcatecholate (DTBcat/sup 2 -/), are prepared by reacting the Mo(VI) dimer. (MoO/sub 2/(Sap))/sub 2/, with the appropriate catechol. The products are characterized by cyclic voltammetry, mass spectrometry, and uv/vis, ir, and /sup 95/Mo NMR spectroscopy. The MoO(cat)(Sap) complexes represent the first examples of a mononuclear MoO/sup 4 +/ center with a coordination number of six. The crystal structure of the MoO-(Naphcat)(Sap) derivative is reported, confirming the six-coordinate, distorted octahedrla environment about Mo(VI). Bond angles in the coordination group deviate from the ideal value of 90/degrees/ as a consequence of the ligand bite constraints and because all four O-Mo-O angles involving the terminal oxo ligand are larger than the ideal 90/degrees/ value. MoO(cat)(Sap) complexes undergo reversible one-electronic reduction at -0.5 to -0.7 V versus Fc /sup +/0/ followed by irreversible one-electron reduction at -1.6 to -1.9 V. Reversible MoO/sup 4 +//MoO/sup 3 +/ electrochemistry is attributed to the fact that the Mo d/sub xy/orbital of MoO(cat)(Sap) can be singly occupied upon reduction to Mo(V) without unfavorable interaction with the four bonds in its equatorial plane. This contrasts with the irreversible electrochemical behavior of seven-coordinate MoO/sup 4 +/ complexes, which contain five such bonds. The /sup 95/Mo NMR chemical shift of MoO(Naphcat)(Sap) is +385 ppM versus external molybdate; this value is highly deshielded with respect to seven-coordinate MoO/sup 4 +/ and six-coordinate MoO/sub 2//sup 2 +/ complexes with O and N donors. 35 references, 4 figures, 5 tables.

  12. Carbazole-degradative IncP-7 plasmid pCAR1.2 is structurally unstable in Pseudomonas fluorescens Pf0-1, which accumulates catechol, the intermediate of the carbazole degradation pathway.

    PubMed

    Takahashi, Yurika; Shintani, Masaki; Li, Li; Yamane, Hisakazu; Nojiri, Hideaki

    2009-06-01

    We determined the effect of the host on the function and structure of the nearly identical IncP-7 carbazole-degradative plasmids pCAR1.1 and pCAR1.2. We constructed Pseudomonas aeruginosa PAO1(pCAR1.2) and P. fluorescens Pf0-1Km(pCAR1.2) and compared their growth on carbazole- and succinate-containing media with that of P. putida KT2440(pCAR1.1). We also assessed the stability of the genetic structures of the plasmids in each of the three hosts. Pf0-1Km(pCAR1.2) showed dramatically delayed growth when carbazole was supplied as the sole carbon source, while the three strains grew at nearly the same rate on succinate. Among the carbazole-grown Pf0-1Km(pCAR1.2) cells, two types of deficient strains appeared and dominated the population; such dominance was not observed in the other two strains or for succinate-grown Pf0-1Km(pCAR1.2). Genetic analysis showed that the two deficient strains possessed pCAR1.2 derivatives in which the carbazole-degradative car operon was deleted or its regulatory gene, antR, was deleted by homologous recombination between insertion sequences. From genomic information and quantitative reverse transcription-PCR analyses of the genes involved in carbazole mineralization by Pf0-1Km(pCAR1.2), we found that the cat genes on the chromosome of Pf0-1Km, which are necessary for the degradation of catechol (a toxic intermediate in the carbazole catabolic pathway), were not induced in the presence of carbazole. The resulting accumulation of catechol may have enabled the strain that lost its carbazole-degrading ability to have overall higher fitness than the wild-type strain. These results suggest that the functions of the chromosomal genes contributed to the selection of plasmid derivatives with altered structures.

  13. Iron(III) complexes of N2O and N3O donor ligands as functional models for catechol dioxygenase enzymes: ether oxygen coordination tunes the regioselectivity and reactivity.

    PubMed

    Sundaravel, Karuppasamy; Suresh, Eringathodi; Saminathan, Kolandaivel; Palaniandavar, Mallayan

    2011-08-28

    A series of mononuclear iron(III) complexes of the type [Fe(L)Cl(3)], where L is a systematically modified N(2)O or N(3)O ligand with a methoxyethyl/tetrahydrofuryl ether oxygen donor atom, have been isolated and studied as models for catechol dioxygenases. The X-ray crystal structures of [Fe(L2)Cl(3)] 2, [Fe(L6)Cl(3)] 6, [Fe(L5)(TCC)Cl] 5a, where H(2)TCC = tetrachlorocatechol, [Fe(L6)(TCC)Br] 6a, and the μ-oxo dimer [{Fe(L6)Cl}(2)O](ClO(4))(2) 6b have been successfully determined. In [Fe(L2)Cl(3)] 2 the N(2)O ligand is facially coordinated to iron(III) through the pyridine and secondary amine nitrogen atoms and the tetrahydrofuryl oxygen atom. In [Fe(L6)Cl(3)] 6, [Fe(L5)(TCC)Cl] 5a and [Fe(L6)(TCC)Br] 6a the N(3)O donor ligands L5 and L6 act as a tridentate N3 donor ligand coordinated through two pyridine and one secondary amine nitrogen atoms, whereas the ether oxygen is not coordinated. The spectral and electrochemical properties of the adducts [Fe(L)(DBC)Cl] of 1-8, where H(2)DBC = 3,5-di-tert-butylcatechol, in DMF and their solvated adduct species [Fe(L)(DBC)(Sol)](+), where Sol = DMF/H(2)O, generated in situ in dichloromethane, respectively, have been investigated. The product analysis demonstrates that the adducts [Fe(L)(DBC)Cl] effect cleavage of catechol in the presence of O(2) in DMF to give mainly the intradiol (I) product with a small amount of the extradiol (E) product (E/I, 0.2:1-0.7:1). Interestingly, the solvated species [Fe(L)(DBC)(Sol)](+) derived from 1-4 cleave H(2)DBC to provide mainly the extradiol cleavage products with lower amounts of intradiol products (E/I, 2.3:1-4.3:1) in dichloromethane. In contrast, the solvated species [Fe(L)(DBC)(Sol)](+) derived from 5-8 cleave H(2)DBC to provide both extradiol and intradiol products (E/I, 0.6:1-2.3:1) due to the involvement of the ether oxygen donor of the methoxyethyl/tetrahydrofuryl arm in the coordination to iron(III) upon removal of a chloride ion. PMID:21766098

  14. Usnic acid.

    PubMed

    Ingólfsdóttir, K

    2002-12-01

    Since its first isolation in 1844, usnic acid [2,6-diacetyl-7,9-dihydroxy