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Artigos de revistas sobre o tema "Hydroxyle radical"

Autor: Grafiati

Publicado: 31 de agosto de 2024

Última modificação: 31 de julho de 2025

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1

Zylber, Jean, Nicole Zylber, Daniel Lefort, Christiane Ferradini, and Bernard Hickel. "Régiosélectivité de la réaction des radicaux hydroxyle et hydroxy-2 propyle-2 avec l'hypoxanthine." Canadian Journal of Chemistry 66, no. 2 (1988): 283–87. http://dx.doi.org/10.1139/v88-048.

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The reactivity of [Formula: see text] and (CH3)2ĊOH radicals with hypoxanthine was studied under comparable γ-irradiation conditions. A difference in regioselectivity of attack by the electrophilic [Formula: see text] radical and the nucleophilic (CH3)2ĊOH radical is observed, the latter leading in 70% yield to a C-8 substituted product. The rate constants of the addition of the radical to hypoxanthine were determined by pulse radiolysis to be k = 1.4 × 108 M−1 s−1 in acid medium, and in neutral medium k = 7 × 105 M−1 s−1. The much more reactive [Formula: see text] radical leads essentially to

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2

Gallard, H., J. De Laat, and B. Legube. "Étude comparative de la vitesse de décomposition de H2O2 et de l'atrazine par les systèmes Fe(III)/H2O2, Cu(II)/H2O2 et Fe(III)/Cu(II)/H2O2." Revue des sciences de l'eau 12, no. 4 (2005): 713–28. http://dx.doi.org/10.7202/705374ar.

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Cette étude a eu pour objectif de comparer les vitesses de décomposition du peroxyde d'hydrogène et d'oxydation de l'atrazine par les systèmes catalytiques Fe(III)/H2O2, Cu(II)/H2O2, et Fe(III)/Cu(II)/H2O2. Les expériences ont été réalisées à pH 3,0, à une température de 25,0 (± 0,2) °C, en milieu perchlorate, en présence et en absence d'oxygène dissous. L'étude comparative a confirmé que les vitesses de décomposition de H2O2 et d'oxydation de l'atrazine sont beaucoup plus lentes en présence de Cu(II) qu'en présence de Fe(III) et l'addition de Cu(II) augmente l'efficacité du système Fe(III)/H2

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3

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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4

Rhim, Tae-Jin, Hee-Sun Jeong, Young-Jin Kim, et al. "A study on the comparison of antioxidant effects among cultivated ginseng, and cultivated wild ginseng extracts -Using the measurement of superoxide and hydroxy radical scavenging activities-." Journal of Korean Institute of Herbal Acupuncture 12, no. 2 (2009): 7–12. http://dx.doi.org/10.3831/kpi.2009.12.2.007.

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5

Choi, Jeong-Hwan, Dong-Hun Shin, Hye-Bin Kim, Jong-Gook Kim, and Kitae Baek. "One-step Oxidation of Total Organic Carbon, Total Nitrogen, and Total Phosphorous using Wet Chemical Oxidation." Journal of Korean Society of Environmental Engineers 42, no. 12 (2020): 603–9. http://dx.doi.org/10.4491/ksee.2020.42.12.603.

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Objective:This study proposed the simultaneous multi-oxidation of total organic carbon, total nitrogen, and total phosphorous using modified wet chemical oxidation method.Methods:The multi oxidation process was based on the dual radical system with sulfate and hydroxyl radicals. The sodium persulfate (Na2S2O8) and sodium hydroxide (NaOH) were activated at 40℃ and UV irradiation with 254 nm to generate the sulfate radical and hydroxyl radical. The organic matters were oxidized by the dual radicals, and TOC, TN, and TP values were compared with the control group.Results and Discussion:The dual r

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6

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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7

Vrecko, Karoline, and Gilbert Reibnegger. "Influence of 7,8 Dihydroneopterin and Hyperoxia on Neurite Growth and Tyrosine Hydroxylase Activity of PC 12 Cells." Pteridines 13, no. 3 (2002): 94–99. http://dx.doi.org/10.1515/pteridines.2002.13.3.94.

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Abstract The influence of dihydroneopterin on tyrosine hydroxylase activity in PC 12 cells was investigated under normoxic and hyperoxic conditions, and with or without iron ions in the incubation medium. Low dihydroneopterin concentrations as well as hyperoxia increase tyrosine hydroxylase activity. Due to a too vigorous radical formation, high dihydroneopterin concentrations lead to a decrease of tyrosine hydroxylation in normoxic state and even more strongly in hyperoxic state. Similar depression of tyrosine hydroxylase activity was seen after addition of iron ions, which can form hydroxyl

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8

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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9

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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10

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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11

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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12

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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13

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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14

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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15

Zuofa Zhang, Jie Jin, and Liangen Shi. "Antioxidant Properties of Ethanolic Extract from Ramulus mori (Sangzhi)." Food Science and Technology International 15, no. 5 (2009): 435–44. http://dx.doi.org/10.1177/1082013209350277.

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The antioxidant properties and total phenolic contents of four fractions of ethanolic extract from Ramulus mori were examined. Various experimental models including superoxide radical, hydroxyl radical, 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH) scavenging activity, metal chelating activity, and reducing power were used for characterization of their antioxidant activity. The four fractions showed various degrees of efficacy in each assay in a dose-dependent manner. The third fraction with the highest amount of total phenolics was the most potent antioxidant in all assays used. In addition,

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16

Wibowo, Heri Budi, Sutrisno Sutrisno, Hamonangan Rekso Diputro Sitompul, et al. "Kinetics of Hydroxyl Growth on Natural Rubber Depolymerization with H2O2/Fenton Using Infrared Spectroscopy." Polymers 17, no. 13 (2025): 1847. https://doi.org/10.3390/polym17131847.

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The kinetics of the depolymerization of natural rubber (NR) to hydroxyl-terminated natural rubber (HTNR) by hydrogen peroxide (H2O2) in the presence of a Fenton catalyst within an acidic milieu and under ultraviolet radiation has been rigorously examined utilizing infrared spectroscopy to determine the alterations in molar mass and the functional characteristics. The kinetic model was analyzed in accordance with the elementary reaction, encompassing the following mechanisms: the interaction between hydroxyl radicals and NR, producing radical NR and hydroxylated NR; the reaction wherein radical

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17

Tong, Hua, Yan Fang Liu, Hongyan Yan, et al. "Theoretical investigation of the chiral transition of serine and the roles of water, hydroxyl radical and hydroxide ion." New Journal of Chemistry 43, no. 31 (2019): 12340–50. http://dx.doi.org/10.1039/c9nj01796h.

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18

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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19

Wang, Rui, Chen-Loung Chen, and Josef S. Gratzl. "Ozonation of pine kraft lignin in alkaline solution. Part 1: Ozonation, characterization of kraft lignin and its ozonated preparations." Holzforschung 58, no. 6 (2004): 622–30. http://dx.doi.org/10.1515/hf.2004.116.

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Abstract Pine kraft lignin was purified to obtain a kraft lignin preparation (KL) with weight average molecular mass (Mw) of 5500. The KL was then ozonated with an ozone-air stream containing 2–2.5% of ozone in 0.1 M sodium hydroxide solution to prepare ozonated kraft lignin preparations with ozone consumption of 10, 25, 30 and 40% per KL; Oz-10-KL, Oz-25-KL, Oz-30-KL and Oz-40-KL, respectively. The pH of reaction mixture was decreased with increasing ozone consumption, while the carboxylic acid content and the Mw of resulting ozonated lignins increase with increasing ozone consumption. The KL

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20

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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21

Wasselin-Trupin, V., G. Baldacchino, and B. Hickel. "Détection des radicaux OH et O2 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 105 and 108 M.Key words: chemiluminescence, pulse radiolysis, hydroxyl radical, superoxyde radical.[Traduit par la Rédaction]

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22

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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23

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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24

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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25

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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Harianingsih, Harianingsih, Nur Qudus, and Tonni Agustionio Kurniawan. "Hydroxyl Radicals Production in Nitrogen Fixation with Addition of Fe2+ Ions Using Plasma Electrolysis." Semarak International Journal of Petroleum and Chemical Engineering 1, no. 1 (2024): 51–62. https://doi.org/10.37934/sijpce.1.1.5162.

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Nitrogen fixation using the Haber-Bosch process generates carbon dioxide emissions, so environmentally friendly alternative technologies are needed. Plasma electrolysis is recommended as a nitrogen fixation method that produces liquid nitrate because it does not generate emissions with raw materials from the natural air. The plasma electrolysis process generates hydroxyl radicals in the nitrate formation process. Thus, the aim of this research is to increase hydroxyl radicals by adding Fe2+ ions. The methods used include characterizing the current and voltage strength in the reactor to observe

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Harianingsih, Harianingsih, Nur Qudus, and Tonni Agustionio Kurniawan. "Hydroxyl Radicals Production in Nitrogen Fixation with Addition of Fe2+ Ions using Plasma Electrolysis." Semarak International Journal of Petroleum and Chemical Engineering 1, no. 1 (2024): 51–62. https://doi.org/10.37934/sijpce.1.1.5162a.

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Nitrogen fixation using the Haber-Bosch process generates carbon dioxide emissions, so environmentally friendly alternative technologies are needed. Plasma electrolysis is recommended as a nitrogen fixation method that produces liquid nitrate because it does not generate emissions with raw materials from the natural air. The plasma electrolysis process generates hydroxyl radicals in the nitrate formation process. Thus, the aim of this research is to increase hydroxyl radicals by adding Fe2+ ions. The methods used include characterizing the current and voltage strength in the reactor to observe

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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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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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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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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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J, Mancini-Filho. "Natural Antioxidants and Tissue Inflammation." Bioequivalence & Bioavailability International Journal 7, no. 2 (2023): 1–3. http://dx.doi.org/10.23880/beba-16000203.

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The phenolic compounds present in food cover a wide range of structures that have different biological properties. Highlighting its antioxidant properties and the presence mainly of spices, herbs and other foods. Some compounds present in spices can be listed for their antioxidant activity, such as: cloves have eugenol, pinene in their composition, cinnamon also has eugenol, limonene, pinene, catechins and other phenolic compounds in their composition, anise has pinene, rutin, apigenin, oregano has apigenin, quercecin, rosmarinic, caffeic, p-coumaric acids, and others. Rosemary presents the ca

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Shi, Wenjuan, Junhua Wang, Lan Wang, et al. "Highly Oxidation-Resistant Anion Exchange Membrane By Immobilized Radical Scavenger." ECS Meeting Abstracts MA2024-02, no. 43 (2024): 2912. https://doi.org/10.1149/ma2024-02432912mtgabs.

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Hydroxide exchange membranes and ionomers (HEMs and HEIs) are crucial components to facilitate the flow of anion groups between the electrode in the electrochemical devices. HEMs consist of polymer backbones and cationic groups within the backbone chain or pendant side chain. The robustness of HEMs is critical to the long-term durability of devices. However, HEMs can be gradually degraded by the attack of hydroxide anion group and the oxidation reaction of radicals. In the past decades, many efforts have been made to mitigate the degradation by hydroxide attack with the utilization of ether-fr

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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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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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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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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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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 (Ã¯Â¿Â½OH), 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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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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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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Zocoler, Analice Martins Daleffi, Andréia Cristina Conegero Sanches, Ingrid Albrecht, and João Carlos Palazzo de Mello. "Antioxidant capacity of extracts and isolated compounds from Stryphnodendron obovatum Benth." Brazilian Journal of Pharmaceutical Sciences 45, no. 3 (2009): 443–52. http://dx.doi.org/10.1590/s1984-82502009000300009.

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The extract from stem bark of Stryphnodendron obovatum Benth. was chromatographed on a Sephadex® LH-20 column, and yielded nine compounds: gallic acid (GA), p-hydroxybenzoic acid (PHB), gallocatechin (GC), epigallocatechin (EPG), 4'-O-methylgallocatechin (MGC), epigallocatechin-(4β→8)-epigallocatechin (EPEP), epigallocatechin-(4β→8)-gallocatechin (EPGC), robinetinidol-(4α→8)-gallocatechin (ROGC) and robinetinidol-(4β→8)-epigallocatechin (ROEP). Evaluation of the antioxidant capacity in vitro by the methods of DPPH free radical (IC50; μg/mL) and reduction of the phosphomolybdenum complex (RAC)

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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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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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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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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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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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Hale, W. B., B. Turner, and J. T. LaMont. "Oxygen radicals stimulate guinea pig gallbladder glycoprotein secretion in vitro." American Journal of Physiology-Gastrointestinal and Liver Physiology 253, no. 5 (1987): G627—G630. http://dx.doi.org/10.1152/ajpgi.1987.253.5.g627.

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In several animal models of cholelithiasis, and in humans with gallstones, hypersecretion of gallbladder mucin is observed. This study was undertaken to determine the effect of oxygen radicals on guinea pig gallbladder glycoprotein secretion in organ culture. Mucosal explants were incubated with [3H]glucosamine hydrochloride to label glycoproteins, then exposed to oxygen radicals generated by chelated ferric iron and ascorbic acid. Marked stimulation of glycoprotein release was observed after a 30-min exposure to the oxygen radical-generating system, and the effect was inhibited by mannitol. T

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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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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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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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