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Formation of pyrogallol ether during thermal oxidation of oak (Quercus iberica L.) lignin in the presence of air oxygen was investigated. A model reaction demonstrated that the substance identified by us as pyrogallol ether (1,2-dioxy-3-methoxybenzene) is derived from syringic aldehyde.
The effect of the desoxycorticosterone on the noradrenaline-induced relaxation of coronary arteries waw studied in vitro, after a known inhibitor of COMT, pyrogallol. Relaxation induced by noradrenaline was enhanced by desoxycorticosterone. Relaxation in response to noradrenaline was increased by desoxycorticosterone. Pyrogallol potentiated the responses of coronary strips to noradrenaline and also reduced or abolished the enhancing effects of desoxycorticosterone. It is concluded that desoxycorticosterone enhances the reponse of coronary smooth muscle to noradrenaline by inhibiting and enzymatic pathway for the inactivation of catecolamines.
The effect of PLP on the adrenaline-induced relaxation of coronary arteries was studied in vitro, after known inhibitor of COMT, Pyrogallol. Relaxation of response to adrenaline were increased by PLP. Pyrogallol potentiated responses of coronary strips to adrenaline and also reduced or abolished the enhancing effects of PLP. It is concluded that PLP enhances the response of coronary smooth muscle to adrenaline by inhibiting a enzymatic pathway for the inactivation of catecholamines.
The effect of PLP on the noradrenaline-induced relaxation of coronary arteries was studied in vitro, after known inhibitor of COMT, Pyrogallol. Relaxation of response to noradrenaline were increased by PLP. Pyrogallol potentiated responses of coronary strips to noradrenaline and also reduced or abolished the enhancing effects of PLP. It is concluded that PLP enhances the response of coronary smooth muscle to noradrenaline by inhibiting a enzymatic pathway for the inactivation of catecolamines.
18O labeling studies on the catechol 1,2-dioxygenase-catalyzed oxidative cleavage of pyrogallol demonstrate that the enzyme functions both as a dioxygenase and a monooxygenase in this reaction. Two products are observed, 2-pyrone-6-carboxylic acid, 99% singly labeled at the carboxylate, and 2-hydroxy-cis,cis-muconic acid, 74% doubly labeled (one 18O at each carboxylate) and 24% single labeled (one 18O at either carboxylate). The labeling pattern observed shows that 2-pyrone-6-carboxylic acid cannot be derived enzymatically from the lactonization of the 2-hydroxy-cis,cis-muconic acid, thus eliminating the dioxetane as an intermediate in the dioxygenase mechanism. The observations are interpreted to indicate the intermediacy of 2-hydroxymuconic anhydride. This anhydride or the corresponding muconyl enzyme species must be sufficiently long-lived to allow the exchange of labeled hydroxide with solvent. Evidence for mechanism-based enzyme inactivation by a pyrogallol-derived intermediate is also presented.
Both intradiol and proximal extradiol dioxygenases are thought to produce the same product, alpha-hydroxymuconic acid, when pyrogallol (3-hydroxycatechol) is used as a substrate. However, when these enzymes were reacted with pyrogallol, they gave different products. A proximal extradiol dioxygenase, metapyrocatechase (catechol:oxygen 2,3-d-oxidoreductase (decyclizing), EC 1.13.11.2), gave a product having an absorption maximum at 290 nm, which was gradually converted to a more stable compound having an absorption maximum at 239 nm. On the other hand, an intradiol dioxygenase, protocatechuate 3,4-dioxygenase (protocatechuate:oxygen 3,4-oxidoreductase (decyclizing), EC 1.13.11.3), gave a product having an absorption maximum at 300 nm. Based on the spectral data and direct comparison with authentic samples, the primary products obtained by the action of the former and the latter enzymes were identified as alpha-hydroxymuconic acid and 2-pyrone-6-carboxylic acid, respectively. While another intradiol dioxygenase, pyrocatechase (catechol:oxygen 1,2-oxidoreductase (decyclizing), EC 1.13.11.1), gave a mixture of nearly equimolar amounts of these two compounds. Isotope labeling experiments indicated that 1 atom of oxygen was incorporated in 2-pyrone-6-carboxylic acid from the atmosphere. Based on these findings, the reaction mechanism for the formation of 2-pyrone-6-carboxylic acid is discussed. This may be the first experimental evidence indicating the presence of a seven-membered lactone intermediate during the oxygenative cleavage of catechols, proposed by Hamilton (Hamilton, G.A. (1974) in Molecular Mechanisms of Oxygen Activation (Hayaishi, O., ed) pp. 405-451, Academic Press, New York).
The adrenaline (AD) induced relaxation in the smooth muscle is increased by bioflavonoids, possibly via cathecol-0-methyltransferase (COMT) inhibition. In order to test this hypothesis, we studied the influence of 4-methylesculetin (4-Me), alone or associated with ascorbic acid, on the response of isolated coronary strips to AD, in the presence of pyrogallol. Both 4-Me being enhanced by the addition of ascorbic acid. The effects were reduced or abolished in the presence off pyrogallol, a well known COMT inhibitor. It is concluded that 4-Me inhibits COMT, as other bioflavonoids.
Methods for quantitating urinary protein differ in their ranges of linearity, technical ease of performance, and applicability to automated analyzers. The Coomassie Brilliant Blue method is widely used but has limited linearity and its tendency to stain glassware has limited its application to automated analyzers. We evaluated a pyrogallol red-molybdate protein dye-binding method (Biotrol USA, Inc.) on a Hitachi 705 analyzer for the quantitation of urinary protein in rats. This method showed a wide range of linearity (up to 2.6 g/l) and good precision. Within-run CVs of 6.6% and 1.3% and between-day CVs of 10.9% and 1.1% were observed at mean protein concentrations of 0.16 g/l and 1.96 g/l, respectively. In addition, rat urine protein results from this method correlated well (r2 = 0.998, n = 40) with a Coomassie Brilliant Blue method (QuanTtest Blue, Quantimetrix Corporation). No significant or unexpected interferences were encountered with this method. We conclude that the automated pyrogallol red-molybdate method is an acceptable and practical alternative to the Coomassie Brilliant Blue method for the quantitation of urine protein in rats.
Auto-oxidation products of plant phenolics in alkaline medium, such as gallic acid and pyrogallol were used to show antigonadotropic activity. The complex mixture of oxidation products was extracted from aqueous medium successively by ethyl ether and ethyl acetate. The fractions obtained were tested on a model of mouse Leydig cells in vitro. All compounds used inhibited luteinizing hormone-stimulated testosterone secretion during 6 and 24 h culture whereas basal secretion was stimulated by pyrogallol oxidation products. Not only low molecular weight substances extracted by organic solvents but also the remaining water soluble, dark brown, high molecular weight products were found to be antigonadotropically active.
Antibody 03-1, which was prepared by immunization with meso-tetrakis(4-carboxyphenyl)porphyrin (TCPP) conjugate, has been found to bind strongly to Mn(III)-TCPP and Fe(III)-TCPP complexes with dissociation constants of 4.1 x 10(-)(7) and 1.5 x 10(-)(7) M, respectively, although other monoclonal antibodies raised against TCPP did not bind to these TCPP-metal complexes. The complexes of antibody 03-1 with Mn(III)-TCPP and Fe(III)-TCPP were found to catalyze oxidation of pyrogallol selectively. A Lineweaver-Burk plot for the oxidation of pyrogallol by the antibody-Fe-TCPP complex showed K(m) = 4.0 mM and k(cat) = 50 min(-)(1). Studies on the effect of the molar ratio of the antibody to metalloporphyrin on the catalytic activity showed that a 1:1 complex was the most effective for the reaction. The effect of salt (NaCl) on the reaction showed that electrostatic interaction between the antibody and the metalloporphyrin was important for the reaction. The antibody-metalloporphyrin complexes are stable enough to show catalytic activity in the presence of an excess amount of H(2)O(2).
Crystals of the molybdo-/iron-sulfur protein pyrogallol:phloroglucinol hydroxyltransferase (transhydroxylase; EC 1.97.1.2) from Pelobacter acidigallici were grown by vapour diffusion in an N(2)/H(2) atmosphere using polyethylene glycol as a precipitant. In this microorganism, transhydroxylase converts pyrogallol to phloroglucinol in a unique reaction without oxygen transfer from water. Growth of crystals suitable for X-ray analysis was strongly dependent on the presence of dithionite as a reducing agent. The crystals belonged to space group P1 and MAD data were collected on the iron K edge to resolutions higher than 2.5 A.
The antioxidants pyrogallol and its oxidative derivative, purpurogallin, both induce colicine E2 as well as base substitution and frameshift mutations. Because of the bactericidal effect of purpurogallin, its mutagenicity could be best demonstrated by short-term exposure followed by dilution on the test plates. The colicine-inducing potential of purpurogallin was also observed when tested directly on the plates.
A high-performance liquid chromatographic method with spectrophotometric detection was developed for the determination of proteins in urine. The proteins were separated on an anion-exchange column and eluted with a Tris-HCl buffer with a gradient of sodium chloride concentration and pH. The separated proteins were mixed with a pyrogallol red-molybdate complex reagent and determined spectrophotometrically. Urinary proteins were well separated without desalting the urine. The reproducibility was satisfactory.
We have investigated the effect of sodium dodecyl sulfate (SDS) upon the response of the Coomassie Brilliant Blue (CBB) and Pyrogallol Red-molybdate (PRM) protein dye-binding assays to interference from aminoglycosides, ampholytes, detergents, phenothiazines, reducing agents, and miscellaneous substances previously reported to interfere with the assays. The CBB assay was less prone to interference than the PRM assay but gave positive interference with the detergents and the phenothiazines and negative interference with dextran sulfate. The PRM assay gave positive interference with the aminoglycosides, ampholytes, and phenothiazines and negative interference with SDS, citric acid, dextran sulfate, EDTA, oxalic acid, and tartaric acid. The level of interference varied in the presence of different proteins (albumin, gamma globulin, alpha1-acid glycoprotein, or lysozyme) and increased when SDS was added to the dye reagents.
The Pyrogallol Red Molybdate (PRM) and Coomassie Brilliant Blue (CBB) protein dye-binding assays have been applied to samples of cerebrospinal fluid (CSF) to investigate protein concentration by dye precipitation prior to sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The protein concentration values of the CSF samples (N=62) showed good agreement between the PRM and CBB assays as indicated by linear regression analysis (y(PRM)=1.033x(CBB)+1.004 in units of mg/l, r=0.99) but the PRM assay was optimal for protein concentration as the PRM protein-dye complex was less soluble allowing protein recovery over a wider working range. Dye precipitation using PRM is recommended as a simple, rapid and economic method for protein concentration of samples of CSF prior to SDS-PAGE.
A modified immunogold-silver enhancement technique that was designed to reduce the nonspecific granular background staining, particularly for application on prokaryotic organisms, is reported. Aerial oxidation of pyrogallol contained in the commercial silver enhancer solution was effectively controlled during storage and in the reaction mixture. A combination of strategies such as storing the reagent under argon, modifying it using 0.5% (w/v) anhydrous sodium sulfite, reducing the concentration of silver ions in the reaction mixture and limiting the length of the silver enhancement reaction considerably reduced the granular background staining. The modified technique was demonstrated on the bacterium Xanthomonas campestris pv. malvacearum (Smith) Dye. A 7-min silver enhancement step produced little background staining, while optimal silver intensification of the bacterium pre-treated with the immunogold label was achieved.
A new kinetic-spectrophotometric method is described for the determination of ultra trace amounts of Pd(II). The methods based on catalytic action of Pd(II) on the oxidation of pyrogallol red (PGR) with hydrogen peroxide at pH 9.7. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of the PGR at 540 nm, for the first 4.5 min from initiation of the reaction. Calibration curve was linear in the range of 0.02-1.00 microg ml(-1) Pd(II). The limit of detection is 0.017 microg ml(-1) Pd(II). The relative standard deviation (R.S.D.) for ten replicate analyses of 0.03 and 0.60 microg ml(-1) Pd(II) was 1.5 and 0.9%, respectively. The influence of more than 40 potential interfering ions was studied for the selectivity. The proposed method was used for the determination of palladium in catalytic material.
Pyrogallol[4]arene forms discrete hexameric capsules in neat normal, branched, and cyclic alkanes. These hydrocarbon guests fill the available space and show chemical exchange that is slow on the NMR time scale. [reaction: see text]