Oxidation of Azo Dyes by Peroxidase: Additional Evidence of a One-Electron Mechanism of Oxidation of Dimethylaminoazobenzene and Sudan I (Solvent Yellow 14)

1996 ◽  
Vol 61 (6) ◽  
pp. 962-972 ◽  
Author(s):  
Marie Stiborová ◽  
Befekadu Asfaw ◽  
Eva Frei ◽  
Heinz H. Schmeiser
Keyword(s):  
Hydrogen Peroxide ◽  
Oxygen Consumption ◽  
Azo Dyes ◽  
Oxidation Mechanism ◽  
Sudan I ◽  
Unknown Structure ◽  
Acidic Conditions ◽  
Mechanism Of Oxidation ◽  
Ph Dependent ◽  
Aminoazo Dyes

In the presence of hydrogen peroxide, peroxidase oxidized aminoazo dyes, the non-aminoazo dye 1-phenylazo-2-hydroxynaphthalene (Sudan I, Solvent Yellow 14), and its C-hydroxy derivatives. The oxidation of azo dyes is a pH-dependent reaction; while slightly acidic conditions are optimal for the aminoazo dyes, a basic pH suits better for Sudan I and its hydroxy derivatives. The oxidation of the carcinogenic Sudan I and dimethylaminoazobenzene catalyzed by peroxidase was investigated in detail. Oxygen consumption was not observed in incubations of peroxidase, azo dyes and hydrogen peroxide. However, oxygen uptake was observed after the addition of glutathione, which indicates that free radical metabolites of these compounds are formed by peroxidase. The results suggest that peroxidase metabolizes Sudan I and dimethylaminoazobenzene through a one-electron oxidation mechanism, giving rise to free radicals. Three of the products of Sudan I oxidation by peroxidase with a hitherto unknown structure were characterized partly by UV/VIS and mass spectroscopy.

A proposed antioxidation mechanism of ergothioneine based on the chemically-derived oxidation product hercynine and further decomposition products

2021 ◽  
Author(s):  
Chika Ando ◽  
Yasujiro Morimitsu
Keyword(s):  
Hydrogen Peroxide ◽  
Oxidation Mechanism ◽  
Major Product ◽  
Oxidation Products ◽  
Liquid Chromatography Mass Spectrometry ◽  
Decomposition Products ◽  
Physiological Conditions ◽  
Chemical Oxidants ◽  
Mechanism Of Oxidation ◽  
Antioxidation Mechanism

Abstract Ergothioneine (ERGO), a thiohistidine betaine, exists in various fungi, plants, and animals. Humans take in ERGO from their diet. ERGO is a strong biological antioxidant, but there are only a limited number of reports about its redox mechanism. The purpose of this study was to clarify the oxidation mechanism of ERGO. Reactions of ERGO with chemical oxidants were performed. The oxidation products of ERGO were analyzed by nuclear magnetic resonance and liquid chromatography-mass spectrometry (LC-MS). The major product of oxidation of ERGO by hydrogen peroxide in physiological conditions was identified as hercynine (histidine betaine). One molecule of ERGO was able to reduce two molecules of hydrogen peroxide. Hercynine was found to react with the more potent oxidant hypochlorite. One unstable decomposition product was detected by LC-MS. As a result, a mechanism of oxidation of ERGO, and hence its physiological antioxidant activity, was developed.

scholarly journals Cytochrome-c aptamer functionalized Pt nanoclusters for enhanced chemodynamic therapy

2021 ◽  
pp. 2141004
Author(s):  
Bo Feng ◽  
Dan Zhao ◽  
Yaowei Peng ◽  
Fu Wang
Keyword(s):  
Hydrogen Peroxide ◽  
Cytochrome C ◽  
Tumor Cells ◽  
Treatment Strategy ◽  
Side Effect ◽  
Dependent Manner ◽  
Pt Nanoclusters ◽  
Acidic Conditions ◽  
Ph Dependent ◽  
Mitochondria Targeting

Catalysis-based chemodynamic therapy (CDT) is an emerging cancer treatment strategy which uses a Fenton-like reaction to kill tumor cells by catalyzing endogenous hydrogen peroxide (H2O[Formula: see text] into a toxic hydroxyl radical ([Formula: see text]OH). The performance of CDT is greatly dependent on PDT agent. Herein, mitochondria-targeting Pt nanoclusters were synthesized using cytochrome c aptamer (CytcApt) as template. The obtained CytcApt-PtNCs can produce [Formula: see text]OH by H2O2 under the acidic conditions. Moreover, CytcApt-PtNCs could kill 4T1 tumor cells in a pH-dependent manner, but had no side effect on normal 293T cells. Therefore, CytcApt-PtNCs possess excellent therapeutic effect and good biosafety, indicating their great potential for CDT.

Ce(IV)-mediated formation of benzenediazonium ion from a non-aminoazo dye, 1-phenylazo-2-hydroxy-naphthalene (Sudan I) and its binding to DNA

1989 ◽  
Vol 54 (7) ◽  
pp. 2021-2026
Author(s):  
Marie Stiborová ◽  
Befekadu Asfaw ◽  
Pavel Anzenbacher
Keyword(s):  
Azo Dyes ◽  
Acidic Medium ◽  
Model System ◽  
Calf Thymus Dna ◽  
Suitable Model ◽  
Principal Product ◽  
Calf Thymus ◽  
Sudan I ◽  
A Minor

Ce(IV) ions in acidic medium convert a carcinogenic non-aminoazo dye, 1-phenylazo-2-hydroxy-naphthalene (Sudan I) into an ultimate carcinogen, which binds to calf thymus DNA. The principal product of Sudan I oxidation by the Ce(IV) system is the benzenediazonium ion. A minor product is the dihydroxyderivative of Sudan I, 1-(4-hydroxyphenylazo)-2,6-dihydroxynaphthalene. Other minor coloured products (yellow and brown) were not identified. The principal product (the benzenediazonium ion) is responsible for the carcinogenicity of Sudan I, as it covalently binds to DNA. Ce(IV) ions in acidic medium represent a suitable model system, which imitates the activation route of carcinogenic azo dyes.

Decoloration of Azo Dyes by Hydrogen Peroxide Catalyzed by Water-Soluble Manganese Porphyrins

1999 ◽  
Vol 69 (12) ◽  
pp. 956-960 ◽  
Author(s):  
J. Tokuda ◽  
R. Ohura ◽  
T. Iwasaki ◽  
Y. Takeuchi ◽  
A. Kashiwada ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Azo Dyes ◽  
Water Soluble ◽  
Manganese Porphyrins

scholarly journals Phosphate-Catalyzed Hydrogen Peroxide Formation from Agar, Gellan, and κ-Carrageenan and Recovery of Microbial Cultivability via Catalase and Pyruvate

2017 ◽  
Vol 83 (21) ◽  
Author(s):  
Kosei Kawasaki ◽  
Yoichi Kamagata
Keyword(s):  
Hydrogen Peroxide ◽  
Phosphate Buffer ◽  
Laboratory Culture ◽  
Colony Count ◽  
Natural Environments ◽  
Ammonium Ions ◽  
Factors Affecting ◽  
Culture Techniques ◽  
Ph Dependent ◽  
Growth Inhibiting

ABSTRACTPreviously, we reported that when agar is autoclaved with phosphate buffer, hydrogen peroxide (H2O2) is formed in the resulting medium (PT medium), and the colony count on the medium inoculated with environmental samples becomes much lower than that on a medium in which agar and phosphate are autoclaved separately (PS medium) (T. Tanaka et al., Appl Environ Microbiol 80:7659–7666, 2014,https://doi.org/10.1128/AEM.02741-14). However, the physicochemical mechanisms underlying this observation remain largely unknown. Here, we determined the factors affecting H2O2formation in agar. The H2O2formation was pH dependent: H2O2was formed at high concentrations in an alkaline or neutral phosphate buffer but not in an acidic buffer. Ammonium ions enhanced H2O2formation, implying the involvement of the Maillard reaction catalyzed by phosphate. We found that other gelling agents (e.g., gellan and κ-carrageenan) also produced H2O2after being autoclaved with phosphate. We then examined the cultivability of microorganisms from a fresh-water sample to test whether catalase and pyruvate, known as H2O2scavengers, are effective in yielding high colony counts. The colony count on PT medium was only 5.7% of that on PS medium. Catalase treatment effectively restored the colony count of PT medium (to 106% of that on PS medium). In contrast, pyruvate was not as effective as catalase: the colony count on sodium pyruvate-supplemented PT medium was 58% of that on PS medium. Given that both catalase and pyruvate can remove H2O2from PT medium, these observations indicate that although H2O2is the main cause of reduced colony count on PT medium, other unknown growth-inhibiting substances that cannot be removed by pyruvate (but can be by catalase) may also be involved.IMPORTANCEThe majority of bacteria in natural environments are recalcitrant to laboratory culture techniques. Previously, we demonstrated that one reason for this is the formation of high H2O2levels in media prepared by autoclaving agar and phosphate buffer together (PT medium). In this study, we investigated the factors affecting H2O2formation from agar. H2O2formation is pH dependent, and ammonium ions promote this phosphate-catalyzed H2O2formation. Amendment of catalase or pyruvate, a well-known H2O2-scavenging agent, effectively eliminated H2O2. Yet results suggest that growth-inhibiting factor(s) that cannot be eliminated by pyruvate (but can be by catalase) are present in PT medium.

scholarly journals A facile and effective method for preparation of 2.5-furandicarboxylic acid via hydrogen peroxide direct oxidation of 5-hydroxymethylfurfural

2017 ◽  
Vol 19 (1) ◽  
pp. 11-16 ◽  
Author(s):  
Shuang Zhang ◽  
Long Zhang
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction Time ◽  
Oxidation Mechanism ◽  
Molar Ratio ◽  
Alkaline Condition ◽  
Optimal Parameters ◽  
Direct Oxidation ◽  
Reaction Parameters ◽  
Alkaline Conditions ◽  
Furandicarboxylic Acid

Abstract In this paper, 2,5-furandicarboxylic acid (FDCA) was efficiently prepared by the direct oxidation of 5-hydroxymethylfurfural (5-HMF) using hydrogen peroxide (H2O2) in alkaline conditions without any catalysts. The effects of reaction parameters on the process were systematically investigated and the optimal parameters were obtained as follows: molar ratio of 5-HMF:KOH:H2O2 was 1:4:8, reaction temperature and reaction time were determined as 70°C and 15 minutes, respectively. Under these conditions, the yield of FDCA was 55.6% and the purity of FDCA could reach 99%. Moreover, we have speculated the detailed oxidation mechanism of 5-HMF assisted by hydrogen peroxide in alkaline condition to synthesize FDCA.

Abstract 355: Effect of Poloxamer 188 on Rat Brain Isolated Mitochondria After Exposure to Hydrogen Peroxide

Circulation ◽  
2019 ◽  
Vol 140 (Suppl_2) ◽  
Author(s):  
Johannes A Pille ◽  
Michele M Salzman ◽  
Anna A Sonju ◽  
Felicia P Lotze ◽  
Josephine E Hees ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Oxygen Consumption ◽  
Mitochondrial Function ◽  
Complex I ◽  
Room Temperature ◽  
In Vitro Model ◽  
Atp Synthesis ◽  
Complex Ii ◽  
Vitro Model

Introduction: In a pig model of myocardial infarction (MI), intracoronary delivered Poloxamer (P) 188 significantly reduces ischemia/reperfusion (IR) injury when given immediately upon reperfusion, with improved mitochondrial function as a predominant effect. As mitochondria are heavily damaged during IR, a direct effect of P188 on mitochondria may lead to better therapy options during reperfusion. To show not only a similar reduction of IR injury by P188 in the brain, but also a direct P188 effect on mitochondria, we established an in-vitro model of IR that consists of damaging isolated rat brain mitochondria with hydrogen peroxide (H 2 O 2 ), one component of ischemia, then applying P188, and analyzing mitochondrial function. Methods: Male Sprague-Dawley rat brains were removed, and the mitochondria isolated by differential centrifugation and Percoll gradients, then kept on ice to slow their bioenergetics prior to any experimental treatments. Mitochondria were exposed to 200 μM H 2 O 2 for 10 min at room temperature with slight agitation; controls received no H 2 O 2 . Samples were then diluted ½ with buffer ± P188 (250 μM after dilution) to simulate reperfusion and treatment, and kept at room temperature for 10 further minutes. ATP synthesis was measured in a luminometer using a luciferase enzymatic assay. Oxygen consumption was measured by closed cell respirometry with an oxygen meter. In both assays, Complex I and Complex II were examined; Complex I substrates glutamate and malate, Complex II substrate succinate plus the Complex I inhibitor rotenone. Statistics: Data are expressed as mean ± SEM. One-Way ANOVA, SNK-Test; Kruskal-Wallis-Test; α=0.05, * vs control. Results: In both Complex I and II, mitochondrial function was significantly impaired by H 2 O 2 , with ATP synthesis affected more at Complex I and oxygen consumption affected more at Complex II. Addition of P188 did not provide any significant improvement in mitochondrial function. Conclusions: Although P188 significantly reduced IR injury when given during reperfusion in a pig model of MI, it does not appear to provide direct protection to mitochondria in this in-vitro model. Whether the exposure to H 2 O 2 causes the appropriate injury for P188 to become effective remains to be elucidated.

scholarly journals A New pH-Dependent Macrocyclic Rhodamine B-Based Fluorescent Probe for Copper Detection in White Wine

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4514 ◽  
Author(s):  
Nour Doumani ◽  
Elias Bou-Maroun ◽  
Jacqueline Maalouly ◽  
Maya Tueni ◽  
Adrien Dubois ◽  
...  
Keyword(s):  
Rhodamine B ◽  
White Wine ◽  
Green Solvent ◽  
Acidic Media ◽  
One Pot ◽  
Acidic Conditions ◽  
Ph Conditions ◽  
Ph Dependent ◽  
Copper Detection ◽  
Color Emission

For efficiently measuring copper (II) ions in the acidic media of white wine, a new chemosensor based on rhodamine B coupled to a tetraazamacrocyclic ring (13aneN4CH2NH2) was designed and synthesized by a one-pot reaction using ethanol as a green solvent. The obtained chemosensor was characterized via NMR, UV and fluorescent spectra. It was marked with no color emission under neutral pH conditions, with a pink color emission under acidic conditions, and a magenta color emission under acidic conditions where copper (II) ions were present. The sensitivity towards copper (II) ions was tested and verified over Ca2+, Ag+, Zn2+, Mg2+, Co2+, Ni2+, Fe2+, Pb2+, Cd2+, Fe3+, and Mn2+, with a detection limit of 4.38 × 10−8 M in the fluorescence spectrum.

scholarly journals Chiral Amphiphilic Secondary Amine-Porphyrin Hybrids for Aqueous Organocatalysis

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3420 ◽  
Author(s):  
Aitor Arlegui ◽  
Pol Torres ◽  
Victor Cuesta ◽  
Joaquim Crusats ◽  
Albert Moyano
Keyword(s):  
Catalytic Activity ◽  
High Yield ◽  
Aldol Reactions ◽  
Free Base ◽  
Reaction Products ◽  
Chirality Transfer ◽  
Base Form ◽  
Low Degree ◽  
Acidic Conditions ◽  
Ph Dependent

Two chiral proline-derived amphiphilic 5-substituted-10,15,20-tris(4-sulfonatophenyl)porphyrins were prepared, and their pH-dependent supramolecular behavior was studied. In neutral aqueous solutions, the free-base form of the hybrids is highly soluble, allowing enamine-based organocatalysis to take place, whereas under acidic conditions, the porphyrinic protonated core of the hybrid leads to the formation of self-assembled structures, so that the hybrids flocculate and their catalytic activity is fully suppressed. The low degree of chirality transfer observed for aqueous Michael and aldol reactions strongly suggests that these reactions take place under true “in water” organocatalytic conditions. The highly insoluble catalyst aggregates can easily be separated from the reaction products by centrifugation of the acidic reaction mixtures, and after neutralization and desalting, the sodium salts of the sulfonated amine-porphyrin hybrids, retaining their full catalytic activity, can be recovered in high yield.

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