Pyrogallol Autoxidation Research Articles

The effect of autoxidation on the methanogenic toxicity and anaerobic biodegradability of pyrogallol

In a previous study, catechin (a condensed tannim monomer) was polymerized by autoxidation treatments. The resulting oligomeric tannins were responsible for the methanogenic toxicity observed in the autoxidized catechin solutions (Field, J. A., Kortekaas, S. & Lettinga, G. (1989). The tannin theory of methanogenic toxicity. Biol. Wastes 29(4) 241-62). In this study the autoxidation of pyrogallol (a hydrolyzable tanning monomer) did not cause extensive polymerization. Initially, some polymerization occurred, producing toxic intermediates that were later destroyed by a destructive type of oxidation caused by prolonged autoxidation treatments. The first intermediate formed, purpurogallin (a dimer), caused a high level of toxicity to both the methanogenic activity and to the anaerobic degradation of pyrogallol. Since purpurogallin is a highly toxic autoxidation product that lacks tannic features, the changes in methanogenic toxicity induced by the autoxidation of pyrogallol cannot be estimated by changes in the oligomeric tannin concentration. Regardless of the reactions that take place during the autoxidation of tannin monomeric derivatives, the initial reactions can potentially lead to colored products of increased methanogenic toxicity. These are later detoxified by prolonged autoxidation, either by polymerization to high MW compounds (with condensed tannin model compounds), or by destruction of the initially toxic intermediates to low MW compounds (with hydrolyzable tannin model compounds).

Assay of superoxide dismutase activity in animal tissues

Convenient assays for superoxide dismutase have necessarily been of the indirect type. It was observed that among the different methods used for the assay of superoxide dismutase in rat liver homogenate, namely the xanthine-xanthine oxidase ferricytochromec, xanthine-xanthine oxidase nitroblue tetrazolium, and pyrogallol autoxidation methods, a modified pyrogallol autoxidation method appeared to be simple, rapid and reproducible. The xanthine-xanthine oxidase ferricytochromec method was applicable only to dialysed crude tissue homogenates. The xanthine-xanthine oxidase nitroblue tetrazolium method, either with sodium carbonate solution, pH 10.2, or potassium phosphate buffer, pH 7·8, was not applicable to rat liver homogenate even after extensive dialysis. Using the modified pyrogallol autoxidation method, data have been obtained for superoxide dismutase activity in different tissues of rat. The effect of age, including neonatal and postnatal development on the activity, as well as activity in normal and cancerous human tissues were also studied. The pyrogallol method has also been used for the assay of iron-containing superoxide dismutase inEscherichia coli and for the identification of superoxide dismutase on polyacrylamide gels after electrophoresis.

An automated analysis for superoxide dismutase enzyme activity.

The pyrogallol autoxidation assay for superoxide dismutase was adapted for analysis by centrifugal analyzer. The precision of the enzymatic assay was estimated using bovine blood superoxide dismutase. Specific activity determined for human erythrocyte superoxide dismutase by the procedure agreed with previously reported determinations. Recovery of bovine blood superoxide dismutase from hemolysates provided a measure of proportional analytic error. Difficulties inherent in attempting to spectrophotometrically assay an enzyme catalyzing a reaction requiring a free radical substrate cannot be eliminated by an automated method. However, the centrifugal analyzer method makes routine enzymatic analysis for superoxide dismutase in numerous samples technically feasible. Moreover, automated analysis can conveniently include a standard such as bovine blood superoxide dismutase when enzyme levels in tissue extracts are assayed. These advantages make the method for assay of superoxide dismutase enzyme activity a useful procedure.

Superoxide radical scavenging ability of centrophenoxine and its salt dependence in vitro

The superoxide radical scavenging ability of centrophenoxine (CPH) and its components (dimethylaminoethanol = DMAE, p-chlorophenoxyacetic acid = PCPA) was studied in vitro using the method of pyrogallol autoxidation, cytochrome c reduction and photoxidation of o-dianisidine in salt free assay media and in the presence of increasing NaCl or KCl concentrations. The CPH proved to be a superoxide radical scavenger in all three systems used, however, the rate constant for this reaction was rather low (1.7 × 10 2 M −1 s −1). This scavenging ability decreased linearly with increasing ionic strength. DMAE and PCPA behaved in a somewhat contradictory manner. The former proved to be a weak superoxide radical generating compound being partially sensitive to the ionic strength. The latter showed either superoxide radical scavenging or generating effects on various assays depending on the actual salt concentrations of the media. On the basis of the results one has to assume that the superoxide radical scavenger ability of CPH may hardly be responsible for the in vivo effects of this compound, therefore, its OH· radical scavenger reactions the rate constant of which is about 10 9 M −1 s −1 (See Ref. 28.) may be of much greater importance.

Superoxide radical scavenging ability of centrophenoxine and its salt dependence in vitro

The superoxide radical scavenging ability of centrophenoxine (CPH) and its components (dimethylaminoethanol = DMAE, p -chlorophenoxyacetic acid = PCPA) was studied in vitro using the method of pyrogallol autoxidation, cytochrome c reduction and photoxidation of o -dianisidine in salt free assay media and in the presence of increasing NaCl or KCl concentrations. The CPH proved to be a superoxide radical scavenger in all three systems used, however, the rate constant for this reaction was rather low (1.7 × 10 2 M −1 s −1 ). This scavenging ability decreased linearly with increasing ionic strength. DMAE and PCPA behaved in a somewhat contradictory manner. The former proved to be a weak superoxide radical generating compound being partially sensitive to the ionic strength. The latter showed either superoxide radical scavenging or generating effects on various assays depending on the actual salt concentrations of the media. On the basis of the results one has to assume that the superoxide radical scavenger ability of CPH may hardly be responsible for the in vivo effects of this compound, therefore, its OH· radical scavenger reactions the rate constant of which is about 10 9 M −1 s −1 (See Ref. 28.) may be of much greater importance.

A simple method for evaluating platelet superoxide dismutase.

A simple and rapid spectrophotometric method for evaluating platelet superoxide dismutase is reported. Platelets prepared avoiding erythrocyte and leucocyte contamination were lysated and tested in a Tris-cacodylic buffer containing pyrogallol. Platelet superoxide dismutase was calculated by evaluating the degree of the pyrogallol autoxidation inhibition induced by platelet lysate. Possible interferences of hydrogen peroxide, peroxidases and reducing substances were excluded. Platelet superoxide dismutase content was studied in 38 healthy subjects and was 19.1 +/- 4.1 U/10(8) platelets or 35 +/- 7.8 U/mg protein.

Effects of ionic strength on the activity of superoxide dismutase in vitro

Changes in superoxide dismutase (SOD) activity were studied in vitro at increasing NaCl or KCl concentrations. SOD activity was measured using two different systems of superoxide radical generation: pyrogallol autoxidation, and xanthine-xanthine oxidase reaction. Pyrogallol autoxidation was directly measured by spectrophotometry, whereas in the second case cytochrome c reduction was followed at 550 nm. The inhibition of SOD on those parameters was taken as measure of SOD activity. Increasing concentrations of NaCl and KCl significantly increased the rate of pyrogallol autoxidation. The inhibitory effect of SOD significantly decreased under the influence of these salts and followed an exponential curve. The two salts studied resulted in essentially identical changes in SOD activity. Increasing concentrations of NaCl and KCl decreased the rate of cytochrome c reduction in the xanthine-xanthine oxidase system. When correcting the results for these primary effects, SOD activity also displayed in this system an exponential decay with increasing salt concentrations. The results are interpreted in terms of the known charge distribution pattern on the surface of the SOD molecule, and of the age-dependent increase of the intracellular potassium and sodium concentrations in the postmitotic cells.

Mechanism of carbon-carbon cleavage of cyclic 1,2-diketones with alkaline hydrogen peroxide. The acyclic mechanism and its application to the basic autoxidation of pyrogallol

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMechanism of carbon-carbon cleavage of cyclic 1,2-diketones with alkaline hydrogen peroxide. The acyclic mechanism and its application to the basic autoxidation of pyrogallolYasuhiko Sawaki and Christopher S. FooteCite this: J. Am. Chem. Soc. 1983, 105, 15, 5035–5040Publication Date (Print):July 1, 1983Publication History Published online1 May 2002Published inissue 1 July 1983https://doi.org/10.1021/ja00353a030RIGHTS & PERMISSIONSArticle Views974Altmetric-Citations47LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (575 KB) Get e-Alerts Get e-Alerts

The Micellar Acceleration of the Reduction of Nitroblue Tetrazolium by Superoxide Anion Radicals during the Autoxidation of Polyphenols

Abstract The rates of the reduction of Nitroblue Tetrazolium by O2− during the autoxidation of pyrogallol, epinephrine, and catechol were increased 110, 55, and 37-fold respectively in the presence of hexadecyltrimethylammonium bromide. A nonionic micelle of polyoxyethylene dodecyl ether also accelerated these reactions. The microenvironment effects on the electron-transfer from O2− to Nitroblue Tetrazolium were discussed.

Involvement of the superoxide anion radical in the autoxidation of pyrogallol and a convenient assay for superoxide dismutase.

The autoxidation of pyrogallol was investigated in the presence of EDTA in the pH range 7.9–10.6.The rate of autoxidation increases with increasing pH. At pH 7.9 the reaction is inhibited to 99% by superoxide dismutase, indicating an almost total dependence on the participation of the superoxide anion radical, O2·−, in the reaction. Up to pH 9.1 the reaction is still inhibited to over 90% by superoxide dismutase, but at higher alkalinity, O2·− ‐independent mechanisms rapidly become dominant.Catalase has no effect on the autoxidation but decreases the oxygen consumption by half, showing that H2O2 is the stable product of oxygen and that H2O2 is not involved in the autoxidation mechanism.A simple and rapid method for the assay of superoxide dismutase is described, based on the ability of the enzyme to inhibit the autoxidation of pyrogallol.A plausible explanation is given for the non‐competitive part of the inhibition of catechol O‐methyltransferase brought about by pyrogallol.

Autoxidation of pyrogallol: general characteristics and inhibition by catalase.

DURING a study of the oxidative polymerization of phenols1, experiments with phenolic monomers included observations on the air oxidation of pyrogallol. The end-product of pyrogallol oxidation is accepted to be the hydroxylated benztropolone, purpurogallin2, which is characterized by two ultraviolet absorption maxima, 270–275 mµ and 310–320 mµ. and a visible maximum in the region of 425 mµ. We have found that purpurogallin is neither the sole nor the terminal product of pyrogallol oxidation, and it is not formed during slow oxidation in homogeneous systems. The present account describes some features of pyrogallol autoxidation reflecting upon the nature of the reaction, and on its biological significance as well, and constitutes in part, a basis for work now in progress on surface-directed polymerization of pyrogallol.