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Artigos de revistas sobre o tema "Radical hydroxyl"

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Publicado: 31 de agosto de 2024

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1

Venkatachalapathi, A., Abdul Kaffoor H, and S. Paulsamy. "In vitro antioxidant activity and polyphenol estimation of methanolic fruit extract of Carissa spinarum L." Journal of Ayurvedic and Herbal Medicine 3, no. 3 (2017): 122–26. http://dx.doi.org/10.31254/jahm.2017.3304.

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Antioxidant property of methanolic fruit extract of the medicinal tree species, Carissa spinarum was evaluated by studying the contents of total phenolics, tannins and flavonoids, free radical scavenging activity using 1,1-diphenyl-2- picryl hydrozyl (DPPH), hydroxyl radical scavenging activity, reducing power activity, ABTS•+ assay and metal chelating activity. The results of the study revealed that both the parts studied were found to have potent antioxidant activity against DPPH, hydroxyl and ABTS•+ radicals with the IC50 value of 88.98 for methanolic fruit extract for DPPH radicals and 849
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2

Utsumi, Hideo, Sang-Kuk Han, and Kazuhiro Ichikawa. "Enhancement of hydroxyl radical generation by phenols and their reaction intermediates during ozonation." Water Science and Technology 38, no. 6 (1998): 147–54. http://dx.doi.org/10.2166/wst.1998.0247.

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Generation of hydroxyl radicals, one of the major active species in ozonation of water was directly observed with a spin-trapping/electron spin resonance (ESR) technique using 5,5-dimethyl-1-pyrrolineN-oxide (DMPO) as a spin-trapping reagent. Hydroxyl radical were trapped with DMPO as a stable radical, DMPO-OH. Eighty μM of ozone produced 1.08 X 10-6M of DMPO-OH, indicating that 1.4% of •OH is trapped with DMPO. Generation rate of DMPO-OH was determined by ESR/stopped-flow measurement. Phenol derivatives increased the amount and generation rate of DMPO-OH, indicating that phenol derivatives en
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3

Rao, Ashwathanarayana. "STUDY ON ANTIOXIDANT AND CYTOTOXIC PROPERTIES OF OLEA DIOICA ROXB. CRUDE EXTRACT AND ITS PURE COMPOUND COLLECTED FROM WESTERN GHATS, KARNATAKA, INDIA." Asian Journal of Pharmaceutical and Clinical Research 10, no. 2 (2017): 356. http://dx.doi.org/10.22159/ajpcr.2017.v10i2.15727.

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Introduction: Olea dioica Roxb. an important medicinal tree plants used by local siddha tribes, belongs to the family Oleaceae. The parts such asleaves, bark, root, and fruits used in the traditional medicine to cure skin diseases, rheumatism, fever, and cancer.Objectives: The anti-oxidant experiment by metal chelating activity, superoxide radicals, hydroxyl radical, 2,2-diphenyl-2-picrylhydrazyl radicals,2,2-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid radical scavenging assays with in vitro cytotoxicity was tested using trypan blue dye exclusiontechnique and 3-(4, 5 dimethylthiazole-2yl
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4

Zheng, Cheng-Dong, Gang Li, Hu-Qiang Li, Xiao-Jing Xu, Jin-Ming Gao, and An-Ling Zhang. "DPPH-Scavenging Activities and Structure-Activity Relationships of Phenolic Compounds." Natural Product Communications 5, no. 11 (2010): 1934578X1000501. http://dx.doi.org/10.1177/1934578x1000501112.

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Thirty-eight phenolic compounds (including 31 flavonoids) were examined for their DPPH radical-scavenging activities, and structure-activity relationships were evaluated. Specifically, the presence of an Ortho-dihydroxyl structure in phenolics is largely responsible for their excellent antiradical activity. 3-Hydroxyl was also essential to generate a high radical-scavenging activity. An increasing number of hydroxyls on flavones with a 3′,4′-dihydroxyl basic structure, the presence of a third hydroxyl group at C-5′, a phloroglucinol structure, glycosylation and methylation of the hydroxyls, an
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5

Duwe, A. K., J. Werkmeister, J. C. Roder, R. Lauzon, and U. Payne. "Natural killer cell-mediated lysis involves an hydroxyl radical-dependent step." Journal of Immunology 134, no. 4 (1985): 2637–44. http://dx.doi.org/10.4049/jimmunol.134.4.2637.

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Abstract The role of oxygen radicals in lysis of K562 target cells by human natural killer (NK) cells was determined by addition of scavengers of these free radicals. Lysis was greatly reduced under hypoxic conditions. Superoxide dismutase and cytochrome c, scavengers of superoxide anions, and catalase and scavengers of hypochlorite had no effect on lysis. Of 15 hydroxyl radical scavengers tested, 13 inhibited lysis. These were not toxic, because cell morphology and spontaneous chromium release were not affected and preculture with scavengers was not inhibitory. These scavengers differed widel
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6

Flitter, W. D., and R. P. Mason. "The spin trapping of pyrimidine nucleotide free radicals in a Fenton system." Biochemical Journal 261, no. 3 (1989): 831–39. http://dx.doi.org/10.1042/bj2610831.

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The reaction of the hydroxyl radical, generated by a Fenton system, with pyrimidine deoxyribonucleotides was investigated by using the e.s.r. technique of spin trapping. The spin trap t-nitrosobutane was employed to trap secondary radicals formed by the reaction of the hydroxyl radical with these nucleotides. The results presented here show that hydroxyl-radical attack on thymidine, 2-deoxycytidine 5-monophosphate and 2-deoxyuridine 5-monophosphate produced nucleotide-derived free radicals. The results indicate that .OH radical attack occurs predominantly at the carbon-carbon double bond of th
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7

Gebicka, L., and J. L. Gebicki. "Scavenging of oxygen radicals by heme peroxidases." Acta Biochimica Polonica 43, no. 4 (1996): 673–78. http://dx.doi.org/10.18388/abp.1996_4463.

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The reactions of two heme peroxidases, horseradish peroxidase and lactoperoxidase and their compounds II (oxoferryl heme intermediates, Fe(IV) = O or ferric protein radical Fe(III)R.) and compounds III (resonance hybrids [Fe(III)-O2-. Fe(II)-O2] with superoxide radical anion generated enzymatically or radiolytically, and with hydroxyl radicals generated radiolytically, were investigated. It is suggested that only the protein radical form of compound II of lactoperoxidase reacts with superoxide, whereas compound II of horseradish peroxidase, which exists only in oxoferryl form, is unreactive to
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8

Bi, Yong Guang, and Chun Chun Liu. "Study on Scavenging Free Radical Activity with Polysaccharides Materials in Chuanxiong Based on Composite Properties of Biomaterials." Advanced Materials Research 583 (October 2012): 244–47. http://dx.doi.org/10.4028/www.scientific.net/amr.583.244.

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By using spectrophotometric detection of the Chuanxiong polysaccharides on the free radical scavenging. The results show that the Chuanxiong polysaccharides on DPPH radical, hydroxyl radical (HO•) and superoxide anion radical (•) clearance. Scavenging ability with the the Chuanxiong polysaccharide concentration increased, and showed the dose-effect relationship. Concentration of 2.0mg/mL when DPPH radicals clear the rate of 35.61%, while the rate of hydroxyl radicals and superoxide anion radical scavenging, clear the rate of 57.78% and 57.14%. Chuanxiong polysaccharide is an ideal natural anti
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9

Wasselin-Trupin, V., G. Baldacchino, and B. Hickel. "Détection des radicaux OH et O–2 issus de la radiolyse de l'eau par chimiluminescence résolue en temps." Canadian Journal of Physiology and Pharmacology 79, no. 2 (2001): 171–75. http://dx.doi.org/10.1139/y00-090.

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A new method for the detection of low concentrations of hydroxyl and superoxide radicals, formed by water radiolysis, is described in this article. The method used is the time resolved chemiluminescence. It has been performed with an electron beam delivered by a Febetron 707 accelerator. This method allows to measure hydroxyl and superoxide radical concentrations in a large range of concentrations, between 10–5 and 10–8 M.Key words: chemiluminescence, pulse radiolysis, hydroxyl radical, superoxyde radical.[Traduit par la Rédaction]
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10

Elliot, A. John, Shahsultan Padamshi, and Jana Pika. "Free-radical redox reactions of uranium ions in sulphuric acid solutions." Canadian Journal of Chemistry 64, no. 2 (1986): 314–20. http://dx.doi.org/10.1139/v86-053.

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The radiolytic reduction of uranyl ions in degassed sulphuric acid solutions containing various organic solutes was studied. It was shown that while ĊOOH, CO2−, and α-hydroxy-alkyl radicals reduced uranyl ions, the β-hydroxy-alkyl radicals and those derived from gluconic acid could not affect the reduction. The oxidation of uranium(IV) by hydrogen peroxide at pH 0.7 involves hydroxyl radicals in a chain mechanism but at pH 2.0 the oxidation proceeds by a non-radical reaction pathway. From the enhancement of the rate of oxidation of uranium(IV) by oxygen in the presence of 2-propanol, a mechani
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11

Kiruthiga, N. "MOLECULAR MODELLING AND EVALUATION ON SYNTHESISED 2-PHENYL-2,3-DIHYDRO-4 H-CHROMAN-4-ONE CORE AGAINST OXIDATIVE STRESS." Journal of Medical pharmaceutical and allied sciences 10, no. 6 (2021): 4060–65. http://dx.doi.org/10.22270/jmpas.v10i6.2557.

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The aim of the study was to synthesis and characterization of 2,3-dihydro-4h-chroman-4-one core screened for antioxidant activity. The oxidative stress was related to the generation of Reactive oxygen species (ROS), which is responsible for the enhancement of several degenerative diseases, such as osteoarthritis, cancer, diabetes, cardiovascular diseases, etc. Due to this fact, the study was targeted for the development of myeloperoxidase inhibitor for overcoming the oxidative stress. The molecular docking analysis were afforded that the titled compounds possess noteworthy potency against myel
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12

Cho, Min, Hyenmi Chung, Wonyong Choi, and Jeyong Yoon. "Different Inactivation Behaviors of MS-2 Phage and Escherichia coli in TiO2 Photocatalytic Disinfection." Applied and Environmental Microbiology 71, no. 1 (2005): 270–75. http://dx.doi.org/10.1128/aem.71.1.270-275.2005.

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ABSTRACT Despite a wealth of experimental evidence concerning the efficacy of the biocidal action associated with the TiO2 photocatalytic reaction, our understanding of the photochemical mechanism of this particular biocidal action remains largely unclear. It is generally accepted that the hydroxyl radical (�OH), which is generated on the surface of UV-illuminated TiO2, plays the main role. However, our understanding of the exact mode of action of the hydroxyl radical in killing microorganisms is far from complete, and some studies report that other reactive oxygen species (ROS) (H2O2 and
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13

Taiwo, F. A., H. J. Powers, E. Nakano, H. R. Griffiths, and D. F. Nugent. "Free radical reactions in atherosclerosis; An EPR spectrometry study." Spectroscopy 20, no. 2 (2006): 67–80. http://dx.doi.org/10.1155/2006/474183.

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The copper catalysed oxidation of homocysteine has been studied by electron paramagnetic resonance (EPR) spectroscopy and spin trapping techniques to determine the nature of free radical species formed under varying experimental conditions. Three radicals; thiyl, alkyl and hydroxyl were detected with hydroxyl being predominant. A reaction mechanism is proposed involving Fenton chemistry. Inclusion of catalase to test for intermediate generation of hydrogen peroxide showed a marked reduction in amount of hydroxyl radical generated. In contrast, the addition of superoxide dismutase showed no sig
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14

Carlsson, Magnus, David Stenman, Gábor Merényi, and Torbjörn Reitberger. "A comparative study on the degradation of cotton linters induced by carbonate and hydroxyl radicals generated from peroxynitrite." Holzforschung 59, no. 2 (2005): 132–42. http://dx.doi.org/10.1515/hf.2005.020.

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Abstract Carbonate (CO3 •−) and hydroxyl (HO•) radicals were chemically produced in cotton linter suspensions using peroxynitrite as a radical precursor. Both radicals could degrade cotton linters, as shown by viscosity and GPC-SEC measurements. As evidenced by the viscosity measurements, the presence of oxygen during the cotton linter treatments slightly increased cellulose degradation by both radicals. For the carbonate radical, more than 90% of the viscosity losses could be recovered by reductive NaBH4 treatment before measuring the viscosity, whereas only approximately 40% of the viscosity
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15

Haire, D. Larry, Yashige Kotake, and Edward G. Janzen. "An EPR/ENDOR study of aminoxyls (nitroxides) capable of intramolecular bonding: hydroxyalkyl radical spin adducts of nitrones." Canadian Journal of Chemistry 66, no. 8 (1988): 1901–11. http://dx.doi.org/10.1139/v88-307.

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A comparison of the effect of solvent and 13C labeling (of the radical addend) on the EPR (electron paramagnetic resonance) spectra of hydroxyalkyl vs. alkyl radical adducts of α-phenyl-N-tert-butyl nitrone (PBN) and 5,5-dimethyl-1-pyrroline-1-oxide (DMPO) has been investigated. The solution ENDOR spectra in toluene and in ethanol are the first examples studied of aminoxyls with hydroxyl substituents in close proximity to the free radical centre. Diastereomeric mixtures of hydroxyalkyl radical adducts are clearly resolved by ENDOR spectroscopy. Conformations of these radicals have been assigne
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16

Gonzalez, Teresa, Franck Peiretti, Catherine Defoort, Patrick Borel, and Roland Govers. "2′,7′-dichlorofluorescin-based analysis of Fenton chemistry reveals auto-amplification of probe fluorescence and albumin as catalyst for the detection of hydrogen peroxide." Biochemical Journal 477, no. 24 (2020): 4689–710. http://dx.doi.org/10.1042/bcj20200602.

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Fluorophore 2′,7′-dichlorofluorescin (DCF) is the most frequently used probe for measuring oxidative stress in cells, but many aspects of DCF remain to be revealed. Here, DCF was used to study the Fenton reaction in detail, which confirmed that in a cell-free system, the hydroxyl radical was easily measured by DCF, accompanied by the consumption of H2O2 and the conversion of ferrous iron into ferric iron. DCF fluorescence was more specific for hydroxyl radicals than the measurement of thiobarbituric acid (TBA)-reactive 2-deoxy-D-ribose degradation products, which also detected H2O2. As expecte
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17

Siriwardhana, Nalin, K. W. Lee, Y. J. Jeon, S. H. Kim, and J. W. Haw. "Antioxidant Activity of Hizikia fusiformis on Reactive Oxygen Species Scavenging and Lipid Peroxidation Inhibition." Food Science and Technology International 9, no. 5 (2003): 339–46. http://dx.doi.org/10.1177/1082013203039014.

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Water and organic extracts (diethyl ether, chloroform, ethyl acetate, acetone, ethanol and methanol) obtained from Hizikia fusiformis were screened on reactive oxygen species (ROS) scavenging assays (1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion, hydrogen peroxide and hydroxyl radical) and lipid peroxidation (inhibition of linoleic acid oxidation) inhibitory assays. Water, methanol and ethanol extracts showed significant ROS radical scavenging activities. Water extracts showed high scavenging activities on hydrogen peroxide (around 76%) and DPPH radicals (around 75%) while it presente
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18

Li, Mengqi, Fuminori Yoneyama, Nayu Toshimitsu, Takeshi Zendo, Jiro Nakayama, and Kenji Sonomoto. "Lethal Hydroxyl Radical Accumulation by a Lactococcal Bacteriocin, Lacticin Q." Antimicrobial Agents and Chemotherapy 57, no. 8 (2013): 3897–902. http://dx.doi.org/10.1128/aac.00638-13.

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ABSTRACTThe antimicrobial mechanism of a lactococcal bacteriocin, lacticin Q, can be described by the toroidal pore model without any receptor. However, lacticin Q showed different degrees of activity (selective antimicrobial activity) against Gram-positive bacteria even among related species. The ability of lacticin Q to induce pore formation in liposomes composed of lipids from different indicator strains indicated that its selective antimicrobial activity could not be attributed only to membrane lipid composition. We investigated the accumulation of deleterious hydroxyl radicals after expos
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19

Li, Cheng Shuai, Ai Ling Du, and Ai Qin Du. "Influence of pH on Hydroxyl Radical Scavenging Ratio by Gingerol." Advanced Materials Research 781-784 (September 2013): 1265–69. http://dx.doi.org/10.4028/www.scientific.net/amr.781-784.1265.

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In this paper, the work was mainly studying influence of pH on Fenton reaction and gingerol scavenging hydroxyl radical. The antioxidant activity of gingerol was characterized by the scavenging hydroxyl ratio and scavenging hydroxyl ratio was analyzed by the spectrophotometry. Hydroxyl radical was produced by Fenton reaction. In the experiment pH and buffer solution have influence on the scavenging hydroxyl radical and Fenton reaction. Gingerol exhibits a strong scavenging radical activity for hydroxyl radical (OH.). The scavenging hydroxyl radical of different extractions of ginger oleoresin
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20

Diaz-Uribe, Carlos, William Vallejo, and Cesar Quiñones. "Physical-Chemical Study of Anthracene Selective Oxidation by a Fe(III)-Phenylporhyrin Derivative." International Journal of Molecular Sciences 21, no. 1 (2020): 353. http://dx.doi.org/10.3390/ijms21010353.

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In this work, we studied the anthracene oxidation by hydroxyl radicals. Hydroxyl radical was generated by reaction of 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin Fe (III) (TPPFe) with hydrogen peroxide under visible radiation at a nitrogen atmosphere. The TPPFe was synthesized by Adler Method followed by metal complexation with Fe (III) chloride hexahydrate. Hydroxyl radical was detected by fluorescence emission spectroscopy and we studied kinetic of anthracene selective oxidation by hydroxyl radicals through the differential method. The TPPFe was characterized by UV-Vis spectrophotometry, D
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21

Carey, M., and S. T. Smale. "Hydroxyl-Radical Footprinting." Cold Spring Harbor Protocols 2007, no. 24 (2007): pdb.prot4810. http://dx.doi.org/10.1101/pdb.prot4810.

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22

Puntarulo, S., and A. I. Cederbaum. "Effect of oxygen concentration on microsomal oxidation of ethanol and generation of oxygen radicals." Biochemical Journal 251, no. 3 (1988): 787–94. http://dx.doi.org/10.1042/bj2510787.

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The iron-catalysed production of hydroxyl radicals, by rat liver microsomes (microsomal fractions), assessed by the oxidation of substrate scavengers and ethanol, displayed a biphasic response to the concentration of O2 (varied from 3 to 70%), reaching a maximal value with 20% O2. The decreased rates of hydroxyl-radical generation at lower O2 concentrations correlates with lower rates of production of H2O2, the precursor of hydroxyl radical, whereas the decreased rates at elevated O2 concentrations correlate with lower rates (relative to 20% O2) of activity of NADPH-cytochrome P-450 reductase,
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23

Derwent, Richard G. "Representing Organic Compound Oxidation in Chemical Mechanisms for Policy-Relevant Air Quality Models under Background Troposphere Conditions." Atmosphere 11, no. 2 (2020): 171. http://dx.doi.org/10.3390/atmos11020171.

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This intercomparison has taken thirteen chemical mechanisms and compared how they treat VOC oxidation and degradation and its relationship to the photochemical formation of ozone and hydroxyl radicals. Here, we have looked in some detail at the incremental responses of hydroxyl radicals to incremental additions of a range of organic compounds under conditions appropriate to the background atmosphere. Most of the time, with most organic compounds and most chemical mechanisms, incremental additions of an organic compound led to depletion of hydroxyl radical concentrations. The chemical mechanism
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24

Chen, Yuan, Yingqi Mi, Jingjing Zhang, et al. "Radical Scavenging Activities of Novel Cationic Inulin Derivatives." Polymers 10, no. 12 (2018): 1295. http://dx.doi.org/10.3390/polym10121295.

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Many saccharides are attractive targets for biomaterial applications, due to their abundance, biocompatibility, and biodegradability. In this article, a synthesis process of 6-N-substituted cationic inulin derivatives, including 6-pyridyl-6-deoxyinulin bromide (PIL), 6-(2-amino-pyridyl)-6-deoxyinulin bromide (2APIL), 6-(3-amino-pyridyl)-6-deoxyinulin bromide (3APIL), 6-(4-amino-pyridyl)-6-deoxyinulin bromide (4APIL), 6-(2,3-diamino-pyridyl)-6-deoxyinulin bromide (2,3DAPIL), 6-(3,4-diamino-pyridyl)-6-deoxyinulin bromide (3,4DAPIL), and 6-(2,6-diamino-pyridyl)-6-deoxyinulin bromide (2,6DAPIL) wa
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25

Moore, Peter W., Jordan P. Hooker, Athanasios Zavras, et al. "Hydroxyl Radicals via Collision-Induced Dissociation of Trimethylammonium Benzyl Alcohols." Australian Journal of Chemistry 70, no. 4 (2017): 397. http://dx.doi.org/10.1071/ch16602.

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The hydroxyl radical is a well known reactive oxygen species important for interstellar, atmospheric, and combustion chemistry in addition to multiple biochemical processes. Although there are many methods to generate the hydroxyl radical, most of these are inorganic based, with only a few originating from organic precursor molecules. Reported herein is the observation that trimethylammonium benzyl alcohols and their corresponding deuterated isotopologues act as a good source of hydroxyl and deuteroxyl radicals in the gas-phase under collision-induced dissociation (CID) conditions. Attempts to
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26

Leser, Micheal, Jessica R. Chapman, Michelle Khine, et al. "Chemical Generation of Hydroxyl Radical for Oxidative ‘Footprinting’." Protein & Peptide Letters 26, no. 1 (2019): 61–69. http://dx.doi.org/10.2174/0929866526666181212164812.

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Background: For almost four decades, hydroxyl radical chemically generated by Fenton chemistry has been a mainstay for the oxidative ‘footprinting’ of macromolecules. Objective: In this article, we start by reviewing the application of chemical generation of hydroxyl radical to the development of oxidative footprinting of DNA and RNA and the subsequent application of the method to oxidative footprinting of proteins. We next discuss a novel strategy for generating hydroxyl radicals by Fenton chemistry that immobilizes catalytic iron on a solid surface (Pyrite Shrink Wrap laminate) for the appli
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27

Ragnar, M., T. Eriksson, and T. Reitberger. "Detection of Radicals Generated by Strong Oxidants in Acidic Media." Holzforschung 53, no. 3 (1999): 285–91. http://dx.doi.org/10.1515/hf.1999.048.

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Summary A new method to study superoxide and hydroxyl radicals in aqueous solution in the pH range 1 to 6 is described and critically evaluated. The method primarily detects superoxide, which reacts with tetranitromethane (TNM) by reductive cleavage. The strongly coloured nitroform anion (ε350nm = 15000M−1 cm−1) formed, is easily measured in a spectrophotometer or in a stopped-flow equipment. Hydroxyl radicals are measured indirectly. In a first step the hydroxyl radical reacts with iso-propyl alcohol to give acetone and superoxide. The superoxide formed is then in a second step detected with
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Tumbas, Vesna, Gordana Cetkovic, Sonja Djilas, et al. "Antioxidant activity of mandarin (Citrus reticulata) peel." Acta Periodica Technologica, no. 41 (2010): 195–203. http://dx.doi.org/10.2298/apt1041195t.

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Mandarin peel, a waste product coming from juice production, was extracted by conventional extraction with 70% acetone. Content of flavonoids in mandarin peel extract (MPE) was determined by HPLC. Hesperidin was the most dominant flavonoid. Free radical scavenging activity of MPE on stable DPPH radicals and reactive hydroxyl radicals was also evaluated. EC50 value determined in spectrophotometrical DPPH radical assay was 0.179 mg/ml, while this value in ESR spin trapping hydroxyl radical assay was 0.415 mg/ml. Also, MPE showed protective effects in stabilising sunflower oil during accelerated
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Xu, Li Ping, and Xin Wang. "Evaluation the Effect of Anti-Oxidation of Chondroitin Sulfate." Advanced Materials Research 989-994 (July 2014): 793–96. http://dx.doi.org/10.4028/www.scientific.net/amr.989-994.793.

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Study of the antioxidant activity of chondroitin sulfate extracted from chicken cartilage. The total antioxidant capacity, inhibition the capacity of anti-superoxide anion, hydroxyl radical, anti-liposome and Alkyl radical was determined, respectively; the effect of the anti-oxidation of chondroitin sulfate was observed. The result indicated that chondroitin sulfate had the strong elimination ability to the five free radicals. The ability of total antioxidant the values of scavenging activities of the maximum inhibition rate to anti-superoxide anion, hydroxyl radical, anti-liposome and alkyl r
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Kozlov, Andrey V., Sabzali Javadov, and Natascha Sommer. "Cellular ROS and Antioxidants: Physiological and Pathological Role." Antioxidants 13, no. 5 (2024): 602. http://dx.doi.org/10.3390/antiox13050602.

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Reactive oxygen species (ROS) are highly reactive oxygen derivatives that include free radicals such as superoxide anion radical (O2•−) and hydroxyl radical (HO•), as well as non-radical molecules hydrogen peroxide (H2O2), peroxynitrite (ONOO−), and hypochlorous acid (HOCl) [...]
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Wang, Ying, Anni B. Hougaard, Wilhelm Paulander, Leif H. Skibsted, Hanne Ingmer, and Mogens L. Andersen. "Catalase Expression Is Modulated by Vancomycin and Ciprofloxacin and Influences the Formation of Free Radicals in Staphylococcus aureus Cultures." Applied and Environmental Microbiology 81, no. 18 (2015): 6393–98. http://dx.doi.org/10.1128/aem.01199-15.

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ABSTRACTDetection of free radicals in biological systems is challenging due to their short half-lives. We have applied electron spin resonance (ESR) spectroscopy combined with spin traps using the probes PBN (N-tert-butyl-α-phenylnitrone) and DMPO (5,5-dimethyl-1-pyrrolineN-oxide) to assess free radical formation in the human pathogenStaphylococcus aureustreated with a bactericidal antibiotic, vancomycin or ciprofloxacin. While we were unable to detect ESR signals in bacterial cells, hydroxyl radicals were observed in the supernatant of bacterial cell cultures. Surprisingly, the strongest sign
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McArdle, A., J. van der Meulen, G. L. Close, et al. "Role of mitochondrial superoxide dismutase in contraction-induced generation of reactive oxygen species in skeletal muscle extracellular space." American Journal of Physiology-Cell Physiology 286, no. 5 (2004): C1152—C1158. http://dx.doi.org/10.1152/ajpcell.00322.2003.

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Contractions of skeletal muscles produce increases in concentrations of superoxide anions and activity of hydroxyl radicals in the extracellular space. The sources of these reactive oxygen species are not clear. We tested the hypothesis that, after a demanding isometric contraction protocol, the major source of superoxide and hydroxyl radical activity in the extracellular space of muscles is mitochondrial generation of superoxide anions and that, with a reduction in MnSOD activity, concentration of superoxide anions in the extracellular space is unchanged but concentration of hydroxyl radicals
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Huang, Chenkun, Qiuyue Chen, Shengqiang Li, and Jian Wang. "The Detection Methods of Hydroxyl Radical: A Review." E3S Web of Conferences 375 (2023): 03009. http://dx.doi.org/10.1051/e3sconf/202337503009.

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Hydroxyl radical (·OH) can rapidly react with biological macromolecules, organic and inorganic substances on account of its strong oxidizing property, so it is widely used in sewage treatment, chemiluminescence analysis, biological macromolecule modification and other fields. The strengthening effect of Hydrodynamic cavitation on chemical reactions depends on the number of free radicals initiated by cavitation. These free radicals are highly reactive and react rapidly with pollutants and other species in wastewater. Therefore, the systematic summary of detection methods of hydroxyl radical and
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34

Rudziński, Krzysztof J., and Rafał Szmigielski. "Aqueous Reactions of Sulfate Radical-Anions with Nitrophenols in Atmospheric Context." Atmosphere 10, no. 12 (2019): 795. http://dx.doi.org/10.3390/atmos10120795.

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Nitrophenols, hazardous environmental pollutants, react promptly with atmospheric oxidants such as hydroxyl or nitrate radicals. This work aimed to estimate how fast nitrophenols are removed from the atmosphere by the aqueous-phase reactions with sulfate radical-anions. The reversed-rates method was applied to determine the relative rate constants for reactions of 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, and 2,4,6-trinitrophenol with sulfate radical-anions generated by the autoxidation of sodium sulfite catalyzed by iron(III) cations at ~298 K. The constants determined w
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35

Jiang, Feng, Jiansha Gao, and Di Lang. "Photocatalytic Selective Degradation of Catechol and Resorcinol on the TiO2 with Exposed {001} Facets: Roles of Two Types of Hydroxyl Radicals." Catalysts 12, no. 4 (2022): 378. http://dx.doi.org/10.3390/catal12040378.

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Photocatalytic studies on contaminant degradation in water suspension generally suggest that the degradation reaction mainly takes place on the surface of the photocatalysts rather than in the water phase. The mechanism of selective degradation is often difficult to distinguish concerning the contribution of adsorption and radical selectivity. This study is thus designed to investigate the roles of two types of hydroxyl radicals, adsorbed hydroxyl radical (·OHa) and free hydroxyl radical (·OHf), on the selective degradation of catechol (CT) and resorcinol (RE). CT and RE are significantly diff
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36

Raja, Boobalan, and Kodukkur Pugalendi. "Evaluation of antioxidant activity of Melothria maderaspatana in vitro." Open Life Sciences 5, no. 2 (2010): 224–30. http://dx.doi.org/10.2478/s11535-010-0005-5.

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AbstractIn this study, an aqueous extract of leaves from Melothria maderaspatana was tested for in vitro antioxidant activity. Free radical scavenging assays, such as hydroxyl radical, hydrogen peroxide, superoxide anion radical and 2,2-diphenyl-1-picryl hydrazyl (DPPH), 2,2’-azinobis-(3-ethyl-enzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, and reducing power assay, were studied. The extract effectively scavenged hydroxyl radical, hydrogen peroxide and superoxide anion radicals. It also scavenged DPPH and ABTS radicals. Furthermore, it was found to have reducing power. All concentra
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37

Shirato, Midori, Hiroyo Ikai, Keisuke Nakamura, et al. "Synergistic Effect of Thermal Energy on Bactericidal Action of Photolysis of H2O2in Relation to Acceleration of Hydroxyl Radical Generation." Antimicrobial Agents and Chemotherapy 56, no. 1 (2011): 295–301. http://dx.doi.org/10.1128/aac.05158-11.

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ABSTRACTThe purpose of the present study is to evaluate the effect of thermal energy on the yield of and the bactericidal action of hydroxyl radical generated by photolysis of H2O2. Different concentrations of H2O2(250, 500, 750, and 1,000 mM) were irradiated with light-emitting diodes (LEDs) at a wavelength of 400 ± 20 nm at 25°C to generate hydroxyl radical. The 500 mM H2O2was irradiated with the LEDs at different temperatures (25, 35, 45, and 55°C). Electron spin resonance spin trapping analysis showed that the yield of hydroxyl radicals increased with the temperature, as well as the concen
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38

Hadjimitova, Vera, Trayko Traykov, Milka Mileva, and Stefan Ribarov. "Effect of Some Psychotropic Drugs on Luminol - Dependent Chemiluminescence Induced by O2–, •OH, HOCl." Zeitschrift für Naturforschung C 57, no. 11-12 (2002): 1066–71. http://dx.doi.org/10.1515/znc-2002-11-1220.

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We studied antioxidant activity of six neuroleptics (chlorpromazine, levomepromazine, promethazine, trifluoperazine and thioridazine) and two antidepressants (imipramine and amitriptyline) in the range of concentration of 10−7−10−4 м. We applied luminol-dependent chemiluminescence to test the ability of these drugs to scavenge the biologically relevant oxygen-derived species: hydroxyl radical, superoxide radical, hypochlorous acid in vitro. We found that the phenothiazines were powerful scavengers of hydroxyl and superoxide radicals. Chlorprothixene, amitriptyline and imipramine had no scaveng
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Mojovic, Milos, Ivan Spasojevic, Mirjana Vuletic, Zeljko Vucinic, and Goran Bacic. "An EPR spin-probe and spin-trap study of the free radicals produced by plant plasma membranes." Journal of the Serbian Chemical Society 70, no. 2 (2005): 177–86. http://dx.doi.org/10.2298/jsc0502177m.

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Plant plasma membranes are known to produce superoxide radicals, while the production of hydroxyl radical is thought to occur only in the cell wall. In this work it was demonstrated using combined spin-trap and spin-probe EPR spectroscopic techniques, that plant plasma membranes do produce superoxide and hydroxyl radicals but by kinetically different mechanisms. The results show that superoxide and hydroxyl radicals can be detected by DMPO spin-trap and that the mechanisms and location of their production can be differentiated using the reduction of spin-probes Tempone and 7-DS. It was shown t
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40

Aditya, Manashi, and Soumen Bhattacharjee. "Foliar anti-diabetic and antioxidant potential of a promising accession of Amaranthus hypochondriacus L.: GC-MS based evidences." Journal of Phytopharmacology 7, no. 2 (2018): 121–26. http://dx.doi.org/10.31254/phyto.2018.7204.

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The present study makes an effort to investigate the foliar neutraceutical potential of a promising green accession of a seed amaranth (Amaranthus hypochondriacus, accession no. IC94661) based on anti-lipid peroxidation property, reducing power, metal chelating activity, hydroxyl radical scavenging property, antidiabetic factor and GC-MS based identification of hydroxyl containing phytochemicals. Methanol and aqueous fractions possessed exhibited better anti-lipid peroxidation, reducing, hydroxyl radical scavenging, and metal chelating properties in the experimental accession. Estimation of an
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41

Lankin, V. Z., O. I. Shadyro, K. B. Shumaev, K. B. Shumaev, A. K. Tikhaze, and A. A. Sladkova. "Non-Enzymatic Methylglyoxal Formation From glucose Metabolites and Generation of Superoxide Anion Radical During Methylglyoxal-Dependent Cross-Links Reaction." Journal of Antioxidant Activity 1, no. 4 (2019): 33–45. http://dx.doi.org/10.14302/issn.2471-2140.jaa-19-2997.

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The paper explores the formation of a-oxoaldehydes during the interaction of glucose metabolites with hydroxyl or alkoxyl radicals. Hydroxyl radicals were generated under radiolysis of aqueous solutions, and alkoxyl radicals (t-BuO) were obtained in the model system tert-butyl hydroperoxide/Fe2+. High-performance liquid chromatography revealed that methylglyoxal was one of the organic products resulting from t-BuO-induced transformations of fructose-1,6-bisphosphate under hypoxic conditions. The interaction of lysine and methylglyoxal one of the main targets of a-oxoaldehydes in proteins was
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42

Francés, Daniel E., María T. Ronco, Juan A. Monti, et al. "Hyperglycemia induces apoptosis in rat liver through the increase of hydroxyl radical: new insights into the insulin effect." Journal of Endocrinology 205, no. 2 (2010): 187–200. http://dx.doi.org/10.1677/joe-09-0462.

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AbstractIn this study, we analyzed the contribution of hydroxyl radical in the liver apoptosis mediated by hyperglycemia through the Bax–caspase pathway and the effects of insulin protection against the apoptosis induced by hyperglycemia. Male adult Wistar rats were randomized in three groups: control (C) (sodium citrate buffer, i.p.), streptozotocin (STZ)-induced diabetic (SID) (STZ 60 mg/kg body weight, i.p.), and insulin-treated SID (SID+I; 15 days post STZ injection, SID received insulin s.c., twice a day, 15 days). Rats were autopsied on day 30. In liver tissue, diabetes promoted a signif
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43

Xiao, Helan, Guoping Cai, and Mingyao Liu. "Hydroxyl radical induced structural changes of collagen." Spectroscopy 21, no. 2 (2007): 91–103. http://dx.doi.org/10.1155/2007/496174.

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Extracellular matrix (ECM) plays an important role in cell differentiation, growth, migration and apoptosis. Collagen is the most abundant protein familyin vivo, but its function has still not been clearly defined yet. Reactive oxygen species (ROS) have a central role in oxidative cell stress. Electron spin resonance (ESR) spectroscopy indicates that type I collagen could uniquely scavenge hydroxyl radicals in dose- and time-dependent manner; whereas BSA and gelatin (a denatured collagen) have no such an effect. However, the mechanism by which type I collagen scavenges hydroxyl radicals is dif
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44

Chang, Chen-Yu, Yung-Hsu Hsieh, Kai-Yuan Cheng, Ling-Ling Hsieh, Ta-Chih Cheng, and Kuo-Shan Yao. "Effect of pH on Fenton process using estimation of hydroxyl radical with salicylic acid as trapping reagent." Water Science and Technology 58, no. 4 (2008): 873–79. http://dx.doi.org/10.2166/wst.2008.429.

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This study estimates the yield of hydroxyl radical using salicylic acid as the trapping reagent and investigates the relationship between hydroxyl radical and pH value. The formation and variation of hydroxyl radical under different pH values were evaluated using reaction products, 2,3-DHBA, 2,5-DHBA, and catechol. The formation rate of hydroxyl radical was dependent on the ratio of ferrous ion to hydrogen peroxide and pH values. The difference between various pH values was explored. The kinetics and mechanisms of hydroxyl radical reactions were established in the Fenton process. Experimental
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45

Orthen, Birgit, Marianne Popp, and Nicholas Smirnoff. "Hydroxyl radical scavenging properties of cyclitols." Proceedings of the Royal Society of Edinburgh. Section B. Biological Sciences 102 (1994): 269–72. http://dx.doi.org/10.1017/s0269727000014226.

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Cyclitols are low molecular weight substances which accumulate in plant cells in response to various environmental stress situations, for example drought (Ford 1984), salinity (Gorham et al. 1984), low temperature (Richter et al. 1990).Apart from their more general role in osmotic adjustment, only in the case of salt stress is their mode of function well understood. Cyclitols (e.g. pinitol) accumulate when plants are exposed to increasing salt concentration (Paul & Cockburn 1989) and act as compatible solutes (Sommer et al. 1990) as defined by Brown & Simpson (1972).The significance of
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46

Novelli, Anna, Luc Vereecken, Birger Bohn, et al. "Importance of isomerization reactions for OH radical regeneration from the photo-oxidation of isoprene investigated in the atmospheric simulation chamber SAPHIR." Atmospheric Chemistry and Physics 20, no. 6 (2020): 3333–55. http://dx.doi.org/10.5194/acp-20-3333-2020.

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Abstract. Theoretical, laboratory, and chamber studies have shown fast regeneration of the hydroxyl radical (OH) in the photochemistry of isoprene, largely due to unimolecular reactions which were previously thought not to be important under atmospheric conditions. Based on early field measurements, nearly complete regeneration was hypothesized for a wide range of tropospheric conditions, including areas such as the rainforest where slow regeneration of OH radicals is expected due to low concentrations of nitric oxide (NO). In this work the OH regeneration in isoprene oxidation is directly qua
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47

Ekanayake, P., Y. D. Lee, and J. Lee. "Antioxidant Activity of Flesh and Skin of Eptatretus Burgeri (Hag Fish) and Enedrias Nebulosus (White Spotted Eel)." Food Science and Technology International 10, no. 3 (2004): 171–77. http://dx.doi.org/10.1177/1082013204044822.

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Ethyl acetate and diethyl ether extracts, previously extracted with methanol, were obtained from flesh and skin of Eptatretus burgeri (hag fish) and Enedrias nebulosus (white spotted eel). Eight different extracts (4 mg/mL) were tested for DPPH free radical scavenging activity and the values were compared with commercial antioxidants (α-tocopherol and BHT). All extracts of E. burgeri exhibited significantly positive results (> 65%) in scavenging DPPH radicals compared to E. nebulosus. Thus, only E. burgeri extracts were tested for dose effect, hydrogen peroxide, hydroxyl radical, superoxide
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48

Shao, Youxiang, Hua Hou, and Baoshan Wang. "Theoretical study of the mechanisms and kinetics of the reactions of hydroperoxy (HO2) radicals with hydroxymethylperoxy (HOCH2O2) and methoxymethylperoxy (CH3OCH2O2) radicals." Phys. Chem. Chem. Phys. 16, no. 41 (2014): 22805–14. http://dx.doi.org/10.1039/c4cp02747g.

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Bandala, Erick R., and Oscar M. Rodriguez-Narvaez. "On the Nature of Hydrodynamic Cavitation Process and Its Application for the Removal of Water Pollutants." Air, Soil and Water Research 12 (January 2019): 117862211988048. http://dx.doi.org/10.1177/1178622119880488.

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Cavitation is considered a high energy demanding process for water treatment. For this study, we used a simple experimental setup to generate cavitation at a low pressure (low energy) and test it for hydroxyl radical production using a well-known chemical probe as a hydroxyl radical scavenger. The conditions for generating the cavitation process (eg, pressure, flow velocity, temperature, and other significant variables) were used to degrade model contaminants, an azo dye and an antibiotic. The amount of hydroxyl radicals generated by the system was estimated using N,N-dimethyl-p-nitrosoaniline
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50

Han, Zhen Xing, Bing Wu, Ian Brown, Mark Beck, and Srini Raghavan. "Detection of HO2•/O2•- Radicals Formed in Aqueous Solutions Irradiated with Megasonic Waves Using a Cavitation Threshold (CT) Cell Set-Up." Solid State Phenomena 219 (September 2014): 170–73. http://dx.doi.org/10.4028/www.scientific.net/ssp.219.170.

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Acoustic cavitation, especially transient cavitation, in solutions is accompanied by a number of physical and chemical effects. Due to high temperature and pressure conditions inside bubbles at their collapse, excitation of various species as well as formation of radicals occurs in solution [1-4]. Water molecules excited by megasonic irradiation typically dissociate to hydrogen and hydroxyl radicals (H• and OH•) [5]. The hydroxyl radical is a strong oxidant while the hydrogen radical has reducing properties. In presence of O2 in the solution, H• reacts with O2 to form hydroperoxyl (HO2•) radic
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