Academic literature on the topic 'Radical hydroxyl'

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Journal articles on the topic "Radical hydroxyl"

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 849.70 for hydroxyl radicals. Therefore methanolic fruit extract of C. spinarum can be considered as a new potential source of natural antioxidants for pharmaceutical industries.
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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 enhance •OH generation during ozonation of water. Ozonation of 2,3-, 2,5-, 2,6-dichlorophenol gave an ESR spectra of triplet lines whose peak height ratio were 1:2:1. ESR parameters of the triplet lines agreed with those of the corresponding dichloro-psemiquinone radical. Ozonation of 2,4,5- and 2,4,6-trichlorophenol gave the same spectra as those of 2,5- and 2,6-dichlorophenol, respectively, indicating that a chlorine group in p-position is substituted with a hydroxy group during ozonation. Amounts of the radical increased in an ozone-concentration dependent manner and were inhibited by addition of hydroxyl radical scavengers. These results suggest that p-semiquinone radicals are generated from the chlorophenols by hydroxyl radicals during ozonation. The p-semiquinone radicals were at least partly responsible for enhancements of DMPO-OH generation.
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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)-2, 5-diphenyltetrazolium bromide assay was conducted.Results: Anti-oxidant experiments revealed that the bark ethanolic extract of the O. dioica plant parts has excellent radical scavenging activity and itsextracted pure compound, Benzene ethanol, 4-hydroxy-alcohol, showed excellent radical scavenging activity higher than the standards used. In vitrocytotoxicity experiments revealed that bark ethanolic extract has excellent cytotoxicity activity and its pure compound benzene-ethanol, 4-hydroxyalcoholalso showed excellentactivitywhichis comparablewith the standardcurcumin.Conclusion: O. dioica bark could be exploited as a valuable source of antioxidant and cytotoxic agent for pharmaceutical industry.Keywords: Olea dioica Roxb, Metal chelating, Superoxide radicals, Hydroxyl radical, 2,2-diphenyl-2-picrylhydrazyl radicals, 2,2-azinobis(3-ethylbenzothiazoline)-6-sulfonic acid radical scavenging,Trypan blue, 3-(4,5dimethylthiazole-2yl)-2,5-diphenyltetrazolium bromide assay, Benzeneethanol, 4-hydroxy-alcohol.
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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, and some other hydroxyls, for example 5-, and 7-hydroxyl in ring A, decreased the radical-scavenging activities of flavonoids and other phenolics.
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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 widely in structure, but degree of inhibition of lysis correlated with their rate constants (k) for reaction with hydroxyl radical (k vs log inhibitor concentration required to decrease lysis by 50%: r = -0.9202, p less than 0.001), showing that inhibition was due to inactivation of the hydroxyl radical. Target cell binding was not reduced at concentrations that inhibited lysis. Inhibitors of the lipoxygenase pathway also decreased lysis, suggesting this pathway to be the source of hydroxyl radicals. In view of the reported requirements for hydroxyl radical-mediated lipid peroxidation for optimal secretory activity in a number of cell types, it appears that the generation of hydroxyl radicals by NK cells is required for delivery of cytotoxic factors.
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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 the pyrimidine base. The e.s.r. studies showed a good correlation with previous results obtained by authors who used x- or gamma-ray irradiation to generate the hydroxyl radical. A thiobarbituric acid assay was also used to monitor the damage produced to the nucleotides by the Fenton system. These results showed qualitative agreement with the spin-trapping studies.
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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 towards superoxide. Compound III of the investigated peroxidases does not react with superoxide. The lactoperoxidase activity loss induced by hydroxyl radicals is closely related to the loss of the ability to form compound I (oxoferryl porphyrin pi-cation radical, Fe(IV) = O(Por+.) or oxoferryl protein radical Fe(IV) = O(R.)). On the other hand, the modification of horseradish peroxidase induced by hydroxyl radicals has been reported to cause also restrictions in substrate binding (Gebicka, L. & Gebicki, J.L., 1996, Biochimie 78, 62-65). Nevertheless, it has been found that only a small fraction of hydroxyl radicals generated homogeneously does inactivate the enzymes.
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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 antioxidants and good prospects for the development of biomedical composites.
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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 mechanism involving the perhydroxyl radical, which reconciles earlier published data on kinetics and oxygen tracer studies, is proposed for the oxygen-uranium(IV) reactions.
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