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Sample records for acid abts radicals

  1. Two New Saccharide Fatty Acid Esters from the Fruit of Morinda citrifolia L. and Their ABTS Radical Scavenging Activities

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    Hong-Cai Zhang

    2013-11-01

    Full Text Available Two n ew saccharide fatty acid esters (1 and (2, and six other compounds were isolated from the fruit of Morinda citrifolia L. (Rubiaceae The structures were established as (2E-oct-2-enoate-2-O-?-D - glucopyranosyl-?-D-glucopyranoside(1, (2E-2,6-dimethyl -6-hydroxyl-oct-2,7-dienoate-2-O-?-D-glucopyranosyl-?-D-glucopyranoside(2, saccharumoside C(3, O-?-D-apiofuranosyl-(1?6-O-?-D-glucopyranosides of 3-methyl-2-butenol(4, 3-methyl-but-2-en-1-yl ?-D-glucopyranosyl (1?6-?-D-glucopyranoside(5, benzyl - glucopyranoside(6, Hexyl-O-?-D-glucopyranoside(7, and caproic acid(8. Compound 1 and 2 showed moderate activity against ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulphonate radical in concentration of 0.1-3.2 mg/mL.

  2. KINETICS PROFILES IN THE REACTION OF ABTS DERIVED RADICALS WITH SIMPLE PHENOLS AND POLYPHENOLS

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    CAROLA HENRIQUEZ

    2004-03-01

    Full Text Available The kinetic profile associated to the reaction of phenols with 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS derived radicals is extremely dependent of the characteristics of the substrate. In particular, polyphenols present complex profiles that can be associated to successive reactions of different reactive centers present in the target molecule. Also, changes in the secondary reactions of the produced radicals can lead to a partial recovery of the ABTS radical concentration at intermediate reaction times, as observed employing 1,4-dihydroxybenzene. Although the kinetic profiles of monophenols are considerably simpler, the stoichiometry of the process is unexpected. For example, the data obtained imply that four radicals are consumed by each p-tertbutylphenol molecule introduced into the system. This large stoichiometric coefficient is not compatible with a simple, phenol promoted, back reduction of the ABTS radical. These results, as well as the overshoot observed employing 1,4-dihydroxybencene, cast doubts on the use of ABTS based methodologies to quantitatively measure the capacity of a given compound to trap free radicals or the amount of free radical scavengers present in complex mixtures

  3. SCAVENGING ACTIVITY OF DICLOFENAC: INTERACTION WITH ABTS RADICAL CATION AND PEROXYL RADICALS

    Scientific Electronic Library Online (English)

    C, ROJO; M. J, ÁLVAREZ-FIGUEROA; M, SOTO; A, CAÑETE; D, PESSOA-MAHANA; C, LÓPEZ-ALARCÓN.

    Full Text Available The scavenging activity of diclofenac was estimated by its capability to bleach ABTS radical cation, and ORAC (oxygen radical absorbance capacity) methodology. In addition, GC-MS technique was used to establish if the lactamic derivative of diclofenac was formed as final product in the interaction w [...] ith peroxyl radicals. Diclofenac bleached ABTS radical cation in a concentration-dependent way. In ORAC assays, diclofenac inhibited the consumption of fluorescein and c-phycocyanin mediated by peroxyl radicals. An ORAC-fluorescein, and ORAC-c-phycocyanin value of 0.3, and 0.004 was estimated, respectively. From the downcurvature observed in Stern-Volmer-like plots, we postulated that the low protection of c-phycocyanin is related to secondary damage of c-phycocyanin by the secondary radical of diclofenac. By GC-MS studies only a 2,6-dichloroaniline derivative was detected as product afterthe reaction with peroxyl radicals.

  4. SCAVENGING ACTIVITY OF DICLOFENAC: INTERACTION WITH ABTS RADICAL CATION AND PEROXYL RADICALS

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    C ROJO

    2009-01-01

    Full Text Available The scavenging activity of diclofenac was estimated by its capability to bleach ABTS radical cation, and ORAC (oxygen radical absorbance capacity methodology. In addition, GC-MS technique was used to establish if the lactamic derivative of diclofenac was formed as final product in the interaction with peroxyl radicals. Diclofenac bleached ABTS radical cation in a concentration-dependent way. In ORAC assays, diclofenac inhibited the consumption of fluorescein and c-phycocyanin mediated by peroxyl radicals. An ORAC-fluorescein, and ORAC-c-phycocyanin value of 0.3, and 0.004 was estimated, respectively. From the downcurvature observed in Stern-Volmer-like plots, we postulated that the low protection of c-phycocyanin is related to secondary damage of c-phycocyanin by the secondary radical of diclofenac. By GC-MS studies only a 2,6-dichloroaniline derivative was detected as product afterthe reaction with peroxyl radicals.

  5. Isolation and the characterization of the degradation products of the mediator ABTS-derived radicals formed upon reaction with polyphenols.

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    Osman, A M; Wong, K K Y; Hill, S J; Fernyhough, A

    2006-02-10

    Two degradation products were obtained from the incubation of the widely used 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), ABTS, radical cations with the polyphenols, (+)-catechin, (-)-epicatechin, and phloroglucinol in acetate buffer (pH 5). The products were purified by reversed-phase chromatography and characterized by UV-visible detection, mass spectrometry, and (1)H NMR spectroscopy. The data allowed us to identify the degradation products as 3-ethyl-6-sulfonate benzothiazolinone imine and the corresponding sulfoxide, 3-ethyl-6-sulfonate benzothiazolone. Elemental composition strongly supported the proposed structures. Our results unequivocally demonstrated that ABTS radicals are not as stable as usually claimed because they could be degraded upon interaction with polyphenols, in addition to being reduced by these antioxidants back to the parent compound. Therefore, it is concluded that caution must be exercised in using ABTS radicals as a basis for the evaluation of antioxidant capacities of pure compounds and/or complex mixtures. PMID:16376855

  6. Evaluation of Antioxidative Activity of Croatian Propolis Samples Using DPPH? and ABTS?+ Stable Free Radical Assays

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    Ivona Jasprica

    2007-05-01

    Full Text Available Propolis is one of the richest sources of plant phenolics (flavonoids and phenolic acids, which are widely recognized as rather strong antioxidants. The aim of our work was to use colored stable free radical (DPPH· and ABTS·+ spectrophotometric and thin-layer chromatographic (TLC assays to study the antioxidative behavior of the phenolics (caffeic acid, galangin and pinocembrin most commonly present in Croatian propolis samples obtained from different Croatian regions. We propose a mathematical model providing a more sophisticated interpretation of the obtained results and a new parameter named antioxidative efficiency (AOE is introduced. The kinetic behaviour of chosen standards determined by spectrophotometric assays follows the exponential decrease of the absorption curve. Explained numerically, AOE represents the absolute value of the first derivative of an absorbance curve in the point A0/e (where A0 is the absorbance measured at t = 0 and e is the natural logarithm base. The advantage of this newly introduced parameter is that it provides an easy and accurate mutual comparison between the rates of antioxidative efficiency of different propolis samples. A TLC assay was only applicable in the case of the DPPH· radical. Dose-response curves were described using a linear function with AOE expressed as a coefficient of the slope. The chromatographic method was shown to be very rapid, reliable and easy-to-perform.

  7. Doxorubicin inhibits oxidation of 2,2?-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) by a lactoperoxidase/H2O2 system by reacting with ABTS-derived radical

    OpenAIRE

    RESZKA, KRZYSZTOF J.; Britigan, Bradley E.

    2007-01-01

    The effect of doxorubicin on oxidation of 2,2?-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) by lactoperoxidase and hydrogen peroxide has been investigated. It was found that: (1) oxidation of ABTS to its radical cation (ABTS•+) is inhibited by doxorubicin as evidenced by its induction of a lag period, duration of which depends on doxorubicin concentration; (2) the inhibition is due to doxorubicin hydroquinone reducing the ABTS•+ radical (stoichiometry 1: 1.8); (3) concomitant with the...

  8. Histamine H3 receptor antagonism by ABT-239 attenuates kainic acid induced excitotoxicity in mice.

    Science.gov (United States)

    Bhowmik, Malay; Saini, Neeru; Vohora, Divya

    2014-09-18

    The multifaceted pathogenesis of temporal lobe epilepsy (TLE) offers a number of adjunctive therapeutic prospects. One such therapeutic strategy could be targeting H3 receptor (H3R) by selective H3R antagonists which are perceived to have antiepileptic and neuroprotective potential. Kainic acid (KA) induced seizure, a reliable model of TLE, triggers epileptogenic events resulting from initial neuronal death and ensuing recurring seizures. The present study aimed to determine whether pre-treatment with ABT-239, a novel H3R antagonist, and its combinations with sodium valproate (SVP) and TDZD-8 (glycogen synthase kinase-3? (GSK3?) inhibitor) can prevent the excitotoxic events in mice exposed to KA (10 mg/kg i.p.). ABT-239 (1 and 3 mg/kg i.p.) significantly attenuated KA-mediated behavioural and excitotoxic anomalies and restored altered expression of Bax, cleaved caspase-3, phospho-Akt (Ser473) and cAMP response element binding protein (CREB). Surprisingly, restoration of Bcl2 and phospho-GSK3? (Ser9) by ABT-239 did not reach the level of statistical significance. Co-administration of ABT-239 (1 and 3 mg/kg) with a sub-effective dose of SVP (150 mg/kg i.p.) yielded improved efficacy than when given alone. Similarly, low and high dose combinations of ABT-239 (1 and 3 mg/kg) with TDZD-8 (5 and 10 mg/kg i.p.) produced greater neuroprotection than any other treatment group. Our findings suggests a neuroprotective potential of ABT-239 and its combinations with SVP and TDZD-8 against KA-induced neurotoxicity, possibly mediated through in part each by modulating Akt/GSK3? and CREB pathways. The use of H3R antagonists as adjuvant in the treatment of human TLE might find potential utility, and can be pursued further. PMID:24952295

  9. Alteration of fatty acids content during cow's and goat's milk fermentation with ABT-2 culture

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    Vedran Sla?anac

    2005-04-01

    Full Text Available In this paper, changes in composition and contents of each fatty acid during fermentation with ABT-2 culture were examined. The objective of this study was to determinate the increase of short (SCFA and medium (MCFA chain fatty acids in goat's and cow's milk during fermentation with ABT-2 culture. The hypothesis of this study was that higher contents of SCFA and MCFA are produced in goat's milk in comparison with cow's milk, during fermentation with ABT-2 culture. Obtained results have shown that fermentation process in goat's milk is faster than in cow's milk. The number of viable cells of probiotic bacteria Lactobacillus acidophilus La-5 and Bifidobacterium spp. was statistically greater in goat's milk than in cow's milk; consequently, pH value decreased more obviously in goat's milk than in cow's milk during whole fermentation process. Increase of SCFA and MCFA contents during fermentation was noted in both types of milk due to activity of bifidobacteria derived from ABT-2 culture. However, considerably higher amounts of examined SCFA and MCFA were produced in goat's milk than in cow's milk.

  10. New Derivatives of 3,4-Dihydroisoquinoline-3-carboxylic Acid with Free-Radical Scavenging, D-Amino Acid Oxidase, Acetylcholinesterase and Butyrylcholinesterase Inhibitory Activity

    OpenAIRE

    Jolanta Solecka; Adam Gu?piel; Magdalena Postek; Joanna Ziemska; Robert Kaw?cki; Katarzyna ??czycka; Agnieszka Osior; Bart?omiej Pietrzak; Krzysztof Pypowski; Agata Wyrzykowska

    2014-01-01

    A series of 3,4-dihydroisoquinoline-3-carboxylic acid derivatives were synthesised and tested for their free-radical scavenging activity using 2,2-diphenyl-1-picrylhydrazyl radical (DPPH·), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS·+), superoxide anion radical (O2·?) and nitric oxide radical (·NO) assays. We also studied D-amino acid oxidase (DAAO), acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) inhibitory activity. Almost each of newly synthesised co...

  11. Methylseleninic acid potentiates multiple types of cancer cells to ABT-737-induced apoptosis by targeting Mcl-1 and Bad

    DEFF Research Database (Denmark)

    Yin, Shutao; Dong, Yinhui; Li, Jinghua; Fan, Linghong; Wang, Lei; Lu, Junxuan; Vang, Ole; Hu, Hongbo

    2012-01-01

    of Mcl-1 with RNAi approach supported the functional significance of this molecular target. More importantly, we identified inactivation of Bad by phosphorylation on ser-136 and ser-112 as a novel mechanism involved in ABT-737 resistance, which can be overcome by combining with MSeA. In addition, we......ABT-737, a novel small molecule inhibitor of Bcl-2 family proteins, holds great promise to complement current cancer therapies. However many types of solid cancer cells are resistant to ABT-737. One practical approach to improve its therapeutic efficacy is to combine with the agents that can...... overcome such resistance to restore the sensitivity. In the present study, a second-generation selenium compound methylseleninic acid (MSeA) synergistically sensitized MDA-MB-231 human breast cancer cells, HT-29 human colon cancer cells and DU145 human prostate cancer cells to apoptosis induction by ABT...

  12. Methylseleninic acid potentiates multiple types of cancer cells to ABT-737-induced apoptosis by targeting Mcl-1 and Bad

    DEFF Research Database (Denmark)

    Yin, Shutao; Dong, Yinhui; Li, Jinghua; Fan, Linghong; Wang, Lei; Lu, Junxuan; Vang, Ole; Hu, Hongbo

    2012-01-01

    ABT-737, a novel small molecule inhibitor of Bcl-2 family proteins, holds great promise to complement current cancer therapies. However many types of solid cancer cells are resistant to ABT-737. One practical approach to improve its therapeutic efficacy is to combine with the agents that can...... of Mcl-1 with RNAi approach supported the functional significance of this molecular target. More importantly, we identified inactivation of Bad by phosphorylation on ser-136 and ser-112 as a novel mechanism involved in ABT-737 resistance, which can be overcome by combining with MSeA. In addition, we...... overcome such resistance to restore the sensitivity. In the present study, a second-generation selenium compound methylseleninic acid (MSeA) synergistically sensitized MDA-MB-231 human breast cancer cells, HT-29 human colon cancer cells and DU145 human prostate cancer cells to apoptosis induction by ABT...

  13. Methylseleninic acid potentiates multiple types of cancer cells to ABT-737-induced apoptosis by targeting Mcl-1 and Bad

    DEFF Research Database (Denmark)

    Yin, Shutao; Dong, Yinhui

    2012-01-01

    ABT-737, a novel small molecule inhibitor of Bcl-2 family proteins, holds great promise to complement current cancer therapies. However many types of solid cancer cells are resistant to ABT-737. One practical approach to improve its therapeutic efficacy is to combine with the agents that can overcome such resistance to restore the sensitivity. In the present study, a second-generation selenium compound methylseleninic acid (MSeA) synergistically sensitized MDA-MB-231 human breast cancer cells, HT-29 human colon cancer cells and DU145 human prostate cancer cells to apoptosis induction by ABT-737, as evidenced by greater than additive enhancement of Annexin V/FITC positive (apoptotic) cells and activation of multiple caspases and PARP cleavage. Mechanistic investigation demonstrated that MSeA significantly decreased basal Mcl-1 expression and ABT-737-induced Mcl-1 expression. Knocking down of Mcl-1 with RNAi approach supported the functional significance of this molecular target. More importantly, we identified inactivation of Bad by phosphorylation on ser-136 and ser-112 as a novel mechanism involved in ABT-737 resistance, which can be overcome by combining with MSeA. In addition, we found that expression of Bax was required for the efficient execution of synergistic sensitization. Our findings, for the first time, provide a strong mechanistic rationale for developing MSeA as a novel sensitizing agent of ABT-737.

  14. Antioxidant components of Viburnum opulus L. determined by on-line HPLC-UV-ABTS radical scavenging and LC-UV-ESI-MS methods.

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    Karaçelik, Ayça Akta?; Küçük, Murat; ?skefiyeli, Zeynep; Aydemir, Sezgin; De Smet, Seppe; Miserez, Bram; Sandra, Patrick

    2015-05-15

    Antioxidant activity of the juice and seed and skin extracts prepared with methanol, acetonitrile, and water of Viburnum opulus L. grown in Eastern Black Sea Region were studied with an on-line HPLC-ABTS method and off-line antioxidant methods, among which a linear positive correlation was observed. The fruit extracts were analysed with the HPLC-UV method optimised with 14 standard phenolics. Identification of the phenolic components in the juice was made using an HPLC-UV-ESI-MS method. Nineteen phenolic compounds in juice were identified by comparing the retention times and mass spectra with those of the standards and the phenolics reported in the literature. The major peaks in the juice belonged to coumaroyl-quinic acid, chlorogenic acid, procyanidin B2, and procyanidin trimer. Quite different antioxidant composition profiles were obtained from the extracts with the solvents of different polarities. The antioxidant activities of the seed extracts were higher than those of the skin extracts in general. PMID:25577058

  15. Practical problems when using ABTS assay to assess the radical-scavenging activity of peptides: Importance of controlling reaction pH and time.

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    Zheng, Lin; Zhao, Mouming; Xiao, Chuqiao; Zhao, Qiangzhong; Su, Guowan

    2016-02-01

    Effects of reaction pH and time on the antioxidant behaviors of Tyr, Trp, Cys, and their related peptides (Tyr-Gly, Tyr-Glu, Tyr-Lys, Trp-Gly, Trp-Glu, Trp-Lys, Cys-Gly and Cys-Gly) in ABTS assay were investigated. Results showed that all these amino acids and peptides displayed a biphasic kinetic pattern with a fast initial step and a slow secondary step. The initial reaction rates of Tyr, Trp and their related peptides were strongly dependent on pH, while those of Cys and Cys-containing peptides were unaffected by pH. They failed to reach equilibrium over the short incubation period of 6-10 min typically used in this assay. Longer incubation time was needed for most of the peptides to approach equilibrium at lower pH. The observed biphasic kinetic pattern as well as the high TEAC values for these amino acids and peptides, could be a result of combined antioxidant behaviors of themselves plus the generated reaction products. PMID:26304349

  16. Characterization of the radical-scavenging reaction of 2-O-substituted ascorbic acid derivatives, AA-2G, AA-2P, and AA-2S: a kinetic and stoichiometric study.

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    Takebayashi, Jun; Tai, Akihiro; Gohda, Eiichi; Yamamoto, Itaru

    2006-04-01

    The aim of this study was to characterize the antioxidant activity of three ascorbic acid (AA) derivatives O-substituted at the C-2 position of AA: ascorbic acid 2-glucoside (AA-2G), ascorbic acid 2-phosphate (AA-2P), and ascorbic acid 2-sulfate (AA-2S). The radical-scavenging activities of these AA derivatives and some common low molecular-weight antioxidants such as uric acid or glutathione against 1,1-diphenyl-picrylhydrazyl (DPPH) radical, 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS+), or galvinoxyl radical were kinetically and stoichiometrically evaluated under pH-controlled conditions. Those AA derivatives slowly and continuously reacted with DPPH radical and ABTS+, but not with galvinoxyl radical. They effectively reacted with DPPH radical under acidic conditions and with ABTS+ under neutral conditions. In contrast, AA immediately quenched all species of radicals tested at all pH values investigated. The reactivity of Trolox, a water-soluble vitamin E analogue, was comparable to that of AA in terms of kinetics and stoichiometrics. Uric acid and glutathione exhibited long-lasting radical-scavenging activity against these radicals under certain pH conditions. The radical-scavenging profiles of AA derivatives were closer to those of uric acid and glutathione rather than to that of AA. The number of radicals scavenged by one molecule of AA derivatives, uric acid, or glutathione was equal to or greater than that by AA or Trolox under the appropriate conditions. These data suggest the potential usage of AA derivatives as radical scavengers. PMID:16595915

  17. Isoprene, sulphoxy radical-anions and acidity

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    Rudzi?ski, K. J.; Gmachowski, L.; Kuznietsova, I.

    2008-12-01

    Transformation of isoprene coupled with autoxidation of SIV in aqueous solutions was studied experimentally and by chemical-kinetic modelling over broad range of solution acidities (pH=3-9) to complement the research on aqueous-phase and heterogeneous transformation of isoprene reported recently by many laboratories. Isoprene significantly slowed down the autoxidation in acidic and basic solutions, and accelerated it slightly in neutral solutions. Simultaneously, production of sulphate ions and formation of solution acidity were significantly reduced. Formation of sulphite and sulphate derivatives of isoprene - sulphurous acid mono-(2-methyl-4-oxo-but-2-enyl) ester (m/z=162.9), sulphurous acid mono-(4-hydroxy-2-methyl-but-2-enyl) ester (m/z=164.9), sulphuric acid mono-(2-methyl-4-oxo-but-2-enyl) ester (m/z=178.9), sulphuric acid mono-(4-hydroxy-2-methyl-but-2-enyl) ester (m/z=180.9) - was indicated by mass spectroscopic analysis of post-reaction mixtures. The results of experiments were explained by changes in a subtle quantitative balance of three superimposed processes whose rates depended in different manner on the acidity of reacting solutions - the scavenging of sulphoxy radicals by isoprene, the formation of sulphoxy radicals during further reactions of isoprene radicals, and the autoxidation of SIV itself. A chemical mechanism based on this idea was explored numerically to show good agreement with experimental data. Interaction of isoprene with sulphur(IV) species and oxygen can possibly result in formation of new organosulphate components of atmospheric aerosols and waters, and influence distribution of reactive sulphur and oxygen species in isoprene-emitting organisms exposed to SIV pollutants.

  18. Isoprene, sulphoxy radical-anions and acidity

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    K. J. Rudzi?ski

    2008-12-01

    Full Text Available Transformation of isoprene coupled with autoxidation of SIV in aqueous solutions was studied experimentally and by chemical-kinetic modelling over broad range of solution acidities (pH=3–9 to complement the research on aqueous-phase and heterogeneous transformation of isoprene reported recently by many laboratories. Isoprene significantly slowed down the autoxidation in acidic and basic solutions, and accelerated it slightly in neutral solutions. Simultaneously, production of sulphate ions and formation of solution acidity were significantly reduced. Formation of sulphite and sulphate derivatives of isoprene – sulphurous acid mono-(2-methyl-4-oxo-but-2-enyl ester (m/z=162.9, sulphurous acid mono-(4-hydroxy-2-methyl-but-2-enyl ester (m/z=164.9, sulphuric acid mono-(2-methyl-4-oxo-but-2-enyl ester (m/z=178.9, sulphuric acid mono-(4-hydroxy-2-methyl-but-2-enyl ester (m/z=180.9 – was indicated by mass spectroscopic analysis of post-reaction mixtures. The results of experiments were explained by changes in a subtle quantitative balance of three superimposed processes whose rates depended in different manner on the acidity of reacting solutions – the scavenging of sulphoxy radicals by isoprene, the formation of sulphoxy radicals during further reactions of isoprene radicals, and the autoxidation of SIV itself. A chemical mechanism based on this idea was explored numerically to show good agreement with experimental data. Interaction of isoprene with sulphur(IV species and oxygen can possibly result in formation of new organosulphate components of atmospheric aerosols and waters, and influence distribution of reactive sulphur and oxygen species in isoprene-emitting organisms exposed to SIV pollutants.

  19. Thiazolidin-4-ones from 3-(Aminomethyl)pyridine, Arenealdehydes and Mercaptoacetic Acid: Synthesis and Radical Scavenger Activity

    Scientific Electronic Library Online (English)

    Adriana M., Neves; Auri R., Duval; Gabriele A., Berwaldt; Daniela P., Gouvêa; Natália P., Flores; Pâmela G. da, Silva; Francieli M., Stefanello; Wilson, Cunico.

    2015-02-01

    Full Text Available The efficient synthesis of fifteen novel thiazolidin-4-ones from reaction of 3-(aminomethyl) pyridine (3-picolylamine), arenealdenhydes and mercaptoacetic acid was described. The desired compounds were obtained in moderated to good yields by two methodologies: conventional heating and ultrasound irr [...] adiation. The thiazolidin-4-ones were fully identified and characterized by nuclear magnetic resonance (NMR), gas chromatography coupled to mass spectrometry (GC?MS) and high resolution mass spectrometry (HRMS) techniques. Four compounds showed radical scavenger activity in the 2,2’-azinobis-3-ethyl-benzothiazoline-6-sulfonic acid (ABTS) assay.

  20. Determination of protective properties of Bardejovske Kuple spa curative waters by rotational viscometry and ABTS assay

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    TOPOLSKA Dominika

    2014-02-01

    Full Text Available Mineral waters from Bardejovske Kupele spa are natural, strongly mineralized, with healing effects. They are classified as hydrocarbonic - containing chloride and sodium - carbonic, cold, hypotonic, with a relatively high boric acid content. Potential anti-oxidative effects of curative waters from Bardejovske Kupele were investigated against the hyaluronan (HA degradation. High-molar-mass HA was exposed to the action of ascorbate and cupric ions, which initiate free-radical chain degradation. Time-dependent changes of dynamic viscosity (h of the HA solutions were monitored by rotational viscometry. The radical scavenging capacity of curative waters was determined by the ABTS assay. Despite a significantly high content of transition metal ions, especially iron, remarkable protective effects of the two curative spa waters were found, namely Alzbeta and Klara. Even though “Alzbeta´s“ iron content was 3.5-fold higher than “Klara´s“, “Alzbeta“ was shown to have better protective properties against the HA degradation compared to “Klara“. Bolus addition of ferric ions to the reaction system instead of the natural iron-containing curative water caused a significant HA degradation. The ABTS decolorization assay revealed that the curative spa waters were proven as poorly effective scavengers of the ABTS·+ cation radical.

  1. El ABTS•+ agente oxidante de diversos compuestos químicos y su mecanismo de reciclado entre la lacasa y el sustrato / The ABTS•+ an oxidant agent of different chemical compounds and its recycling process between laccase susbtrate

    Scientific Electronic Library Online (English)

    M, Solís-Oba; E, Bárzana; M, García-Garibay; G, Viniegra-González.

    2007-12-01

    Full Text Available La lacasa comercial obtenida de Myceliophtera termophila y expresada sobre Aspergillus oryzae se empleó para producir un cation radical estable y muy activo del mediador químico ABTS (ácido 2,2'-azino-bis-(3-etillbenzotiazolin-6-sulfonico) con el fin de probar la factibilidad de emplearlo como un in [...] termediario para la oxidación de una variedad de compuestos aromáticos en ausencia de la enzima. Se demostró que el catión radical ABTS•+ por si mismo oxidó al azul índigo, ácido tánico, ácido gálico, azul brillante G, azul de Coomassie, naranja 7 y p-cresol. La reacción de oxidación reveló cambios importantes en sus espectros de absorción en la región del espectro visible. Se demostró también que la oxidación de estos compuestos por la mezcla de lacasa y ABTS se puede efectuar de forma cíclica, de tal forma que la velocidad de reacción fue 94 veces mayor para el índigo, 17 veces mayor para el azul brillante G, 34 veces mayor para el naranja 7 y 5 veces mayor para el p-cresol, comparado con usar el mediador o la lacasa en forma individual. Estos resultados muestran la factibilidad de un esquema de reciclado para la oxidación final de una variedad de compuestos orgánicos en los cuales la enzima no este directamente en contacto con el mismo y que se efectúe a través del mediador ABTS•+. Abstract in english The commercial enzyme laccase cloned from Myceliophtera termophila and expressed in Aspergillus oryzae was used to produce an active, stable and oxidized form of the chemical mediator ABTS (2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid)) in order to test the feasibility of using the monoca [...] tion ABTS•+ as a recyclable intermediate for the oxidation of a variety of aromatic chemicals in the absence of the enzyme. It was shown that ABTS•+, by itself, oxidized, indigo blue, tannic and galic acids, brilliant blue G, Coomassie blue, orange 7 and p-cresol. Oxidation was assessed by important changes in their visible absorption spectra. It was also shown that oxidation of these compounds by a mixture of ABTS and laccase can be done in a cyclic manner, such a way the oxidation rate was 94 times higher for indigo, 17 times for brilliant blue G, 34 times for orange 7 and 5 times higher for p-cresol compared with using the mediator or the laccase alone. Those results show the feasibility of a recycling scheme for the final oxidation of a wide variety of aromatic compounds in which the enzyme is not directly in contact with the compound but through the intermediate ABTS•+.

  2. Radical processes in radiolysis of monocarboxylic acids in liquid phase

    International Nuclear Information System (INIS)

    A possibility of investigating short-lived radicals arising at radiolysis of liquid monocarbon acids, particularly, acetic and propionic acids by means of spin traps (c-phenyl-ter.butylnitron, ter.-butylmethylenenitron, ter.-nitroisobuthane, 2, 4, 6-tri-ter.-butyl-nitrosobenzene) is disclosed. Solutions of spin traps have been vacuumized and ?-irradiated with 60Co at 20 deg or - 196 deg, then they have been frozen. EPR spectra have been taken at temperatures from - 24 to 10 deg. Alkyl and acyl radicals are the basic radical products of radiolysis of acetic and propionic acids while CH2COOH and CH3CHCOOH are, probably, formed as secondary products. Additions of effective electron acceptor-benzophenone decrease yield of adducts with acyl radicals in the propionic acid and they do not affect yield of adducts with C2H5

  3. ESR study of the acid dissociation of NH protons. II. Cyclic peptide radicals and related radicals

    International Nuclear Information System (INIS)

    Free radicals formed by the reaction of OH or O- radicals with alicyclic compounds containing a peptide group (-CONH-) and structurally related compounds have been studied by the in situ radiolysis-steady state ESR method. Eight cyclic peptide radicals resulting from hydrogen abstraction from the C-H bond adjacent to the peptide group have been observed. They are divided into two groups on the basis of the skeletal structure of the radicals: greater than C-NH-CO- and greater than C-CO-NH-. In basic solutions significant changes occur in the ESR parameters of these radicals which can be interpreted in terms of the dissociation of the NH proton in a peptide group. The pK/sub a/ values for the NH proton dissociation have been determined to be in the range of 7.6 to 13.6 for eight cyclic peptide radicals from 5-methyl-2-pyrrolidinone, 2-pyrrolidinone, 2-pyrrolidone-5-carboxylic acid, hydantoin (for both first and second NH proton dissociations), 1-methylhydantoin, 2-thiohydantoin (second dissociation only), succinimide, and 2,5-piperazinedione (first dissociation only) and 10.9 for a related cyclic radical from 2-oxazolidone. These pK/sub a/ values are considerably lower than those for corresponding linear peptide radicals, partly because ?-electron density on the nitrogen atom decreases in cyclic peptide radicals with a more delocalized ?-electron system. Within each group of cyclicpeptide radicals with greater than C-NH-CO- or greater than C-CO-NH- the same trend of changes in ESR parameters was observed upon the dissociation of peptide proton

  4. Free radical scavenging activity of ethanolic extracts from herbs and spices commercialized in Brazil

    OpenAIRE

    Lilian Regina Barros Mariutti; Gisela Pizarro de Mattos Barreto; Neura Bragagnolo; Adriana Zerlotti Mercadante

    2008-01-01

    Ethanolic extracts from 23 different dried herbs and spices commercialized in Brazil were investigated for their free radical scavenging properties using the stable free radicals 2,2'-diphenyl-?-picrylhydrazyl (DPPH•) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS•+), and Trolox as reference (TEAC) for both radicals. The kinetic curves for both radicals showed to follow the first order kinetics model and the decay rate constant (k obs) was calculated. For a...

  5. Free radical scavenging activity of Eagle tea and their flavonoids

    Directory of Open Access Journals (Sweden)

    Qiong Meng

    2012-06-01

    Full Text Available In this study, an online HPLC-DAD-MS coupled with 2,2?-azinobis (3-ethylbenzthiazoline-6-sulfonic acid diammonium salt (ABTS assay was employed for evaluating free radical scavenging activity of Eagle tea and their active components. Twenty-three chromatographic peaks were detected, and nineteen components had free radical scavenging activity. Among them, eight compounds were identified as flavonoids (hyperin, isoquercitrin, quercitrin, quercetin, kaempferol, catechins, chlorogenic acid and epicatechin based on MS data and standard chromatographic characters.

  6. treatment with laccase and abts

    Directory of Open Access Journals (Sweden)

    Myrna Solís-Oba

    2008-01-01

    Full Text Available El sistema ABTS (ácido 2,2´-[3-etil benzotiazolin-6-sulfónico]-lacasa se empleó para decolorar tanto tela de mezclilla como una solución preparada de índigo. Después del tratamiento, la mezclilla adquirió un aspecto de usada, sin que las fibras mostraran evidencia de daño, mientras que la solución de índigo se decoloró. Adicionalmente, el análisis de la biodegradación de los desechos acuosos de la decoloración de la mezclilla y la solución decolorada control de índigo mostraron que, en ambos casos el agua residual fue fácilmente biodegradada tanto aeróbica como anaeróbicamente, mientras que la solución control de índigo requirió de 5 días para biodegradarse aeróbicamente y no sufrió ningún cambio en el sistema anaeróbico. El ABTS oxidado ó la lacasa por sí solos no decoloraron la mezclilla ni la solución de índigo bajo las mismas condiciones experimentales en que se empleó la combinación de ambos ABTS-lacasa. Esto se explica porque, durante la reacción de decoloración, el mediador se recicla varias veces entre la enzima y el colorante, de tal forma que en 30 minutos, una molécula de ABTS oxida 800 moléculas de índigo, además la velocidad de decoloración fue dos órdenes de magnitud mayor que la velocidad cuando se empleó el ABTS ó la enzima en forma individual.

  7. Antioxidant activity of selected phenols estimated by ABTS and FRAP methods

    Directory of Open Access Journals (Sweden)

    Izabela Biskup

    2013-09-01

    Full Text Available Introduction: Phenols are the most abundant compounds in nature. They are strong antioxidants. Too high level of free radicals leads to cell and tissue damage, which may cause asthma, Alzheimer disease, cancers, etc. Taking phenolics with the diet as supplements or natural medicines is important for homeostasis of the organism. Materials and methods: The ten most popular water soluble phenols were chosen for the experiment to investigate their antioxidant properties using ABTS radical scavenging capacity assay and ferric reducing antioxidant potential (FRAP assay. Results and discussion: Antioxidant properties of selected phenols in the ABTS test expressed as IC50 ranged from 4.332 ?M to 852.713 ?M (for gallic acid and 4- hydroxyphenylacetic acid respectively. Antioxidant properties in the FRAP test are expressed as ?mol Fe2 /ml. All examined phenols reduced ferric ions at concentration 1.00 x 10-3 mg/ml. Both methods are very useful for determination of antioxidant capacity of water soluble phenols.

  8. Comparative Evaluation of the Radical-Scavenging Activities of Fucoxanthin and Its Stereoisomers

    Directory of Open Access Journals (Sweden)

    Yiping Zhang

    2014-02-01

    Full Text Available Fucoxanthin (Fuco is a characteristic carotenoid of brown seaweeds. In the present study, Fuco and its stereoisomers 9'Z-Fuco, 13Z- and 13'Z-Fuco were extracted from Laminaria japonica Aresch. They were isolated and purified by silica gel column chromatography, Sephadex LH-20, and reversed-phase HPLC. The radical-scavenging activities of the three stereoisomers were evaluated toward 1,1-diphenyl-2-picrylhydrazyl (DPPH radical, 2-2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS radical, hydroxyl radical, and superoxide radical. The order of 1,1-diphenyl-2-picrylhydrazyl (DPPH radical-scavenging activity was 13Z- and 13'Z-Fuco > (all-E-Fuco > 9'Z-Fuco. The order of 2-2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS and hydroxyl radical-scavenging activities were 9'Z-Fuco > (all-E-Fuco > 13Z-and 13'Z-Fuco. The order of superoxide radical-scavenging activity was 13Z- and 13'Z-Fuco > (all-E-Fuco > 9'Z-Fuco. The scavenging activities of Fuco and its stereoisomers toward the four radical types were all dose-dependent. The ABTS, DPPH, and superoxide radical-scavenging activities were all weaker than that of tocopherol (VE, while their hydroxyl radical-scavenging activities were stronger than that of VE. The results confirmed that Fuco and its stereoisomers have potent antioxidant activities.

  9. Comparative evaluation of the radical-scavenging activities of fucoxanthin and its stereoisomers.

    Science.gov (United States)

    Zhang, Yiping; Fang, Hua; Xie, Quanling; Sun, Jipeng; Liu, Rui; Hong, Zhuan; Yi, Ruizao; Wu, Hao

    2014-01-01

    Fucoxanthin (Fuco) is a characteristic carotenoid of brown seaweeds. In the present study, Fuco and its stereoisomers 9'Z-Fuco, 13Z- and 13'Z-Fuco were extracted from Laminaria japonica Aresch. They were isolated and purified by silica gel column chromatography, Sephadex LH-20, and reversed-phase HPLC. The radical-scavenging activities of the three stereoisomers were evaluated toward 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, 2-2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical, hydroxyl radical, and superoxide radical. The order of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity was 13Z- and 13'Z-Fuco > (all-E)-Fuco > 9'Z-Fuco. The order of 2-2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and hydroxyl radical-scavenging activities were 9'Z-Fuco > (all-E)-Fuco > 13Z-and 13'Z-Fuco. The order of superoxide radical-scavenging activity was 13Z- and 13'Z-Fuco > (all-E)-Fuco > 9'Z-Fuco. The scavenging activities of Fuco and its stereoisomers toward the four radical types were all dose-dependent. The ABTS, DPPH, and superoxide radical-scavenging activities were all weaker than that of tocopherol (VE), while their hydroxyl radical-scavenging activities were stronger than that of VE. The results confirmed that Fuco and its stereoisomers have potent antioxidant activities. PMID:24549234

  10. Mechanism of protection of adenosine from sulphate radical anion and repair of adenosine radicals by caffeic acid in aqueous solution

    Indian Academy of Sciences (India)

    M Sudha Swaraga; L Charitha; M Adinarayana

    2005-07-01

    The photooxidation of adenosine in presence of peroxydisulphate (PDS) has been studied by spectrophotometrically measuring the absorbance of adenosine at 260 nm. The rates of oxidation of adenosine by sulphate radical anion have been determined in the presence of different concentrations of caffeic acid. Increase in [caffeic acid] is found to decrease the rate of oxidation of adenosine suggesting that caffeic acid acts as an efficient scavenger of $SO_{4}^{\\bullet-}$ and protects adenosine from it. Sulphate radical anion competes for adenosine as well as for caffeic acid. The quantum yields of photooxidation of adenosine have been calculated from the rates of oxidation of adenosine and the light intensity absorbed by PDS at 254 nm, the wavelength at which PDS is activated to sulphate radical anion. From the results of experimentally determined quantum yields (exptl) and the quantum yields calculated (cal) assuming caffeic acid acting only as a scavenger of $SO_{4}^{\\bullet-}$ show that exptl values are lower than cal values. The ' values, which are experimentally found quantum yield values at each caffeic acid concentration and corrected for $SO_{4}^{\\bullet-}$ scavenging by caffeic acid, are also found to be greater than exptl values. These observations suggest that the transient adenosine radicals are repaired by caffeic acid in addition to scavenging of sulphate radical anions.

  11. Pulse radiolytic study of the acid dissociation of OH protons in radicals related to salicylic acid

    International Nuclear Information System (INIS)

    The deprotonation of carboxylated benzosemiquinone radicals prepared by pulse radiolytic oxidation of dihydroxybenzoic acids has been examined by time-resolved absorption spectrophotometry. The pK/sub a/ for dissociation of the OH proton in 3-carboxyl-1,4-benzosemiquinone is found to be 6.47 or 2.4 units higher than that in the unsubstituted radical. This pK/sub a/ is, however, well below that of the OH proton in salicyclic acid (13.6) so that hydrogen bonding is appreciably decreased by the delocalization of the unpaired spin in this radical. Protonation of the basic form of the radical occurs at the diffusion-controlled rate. The rate constant for deprotonation by OH- is relatively low, 4.7 X 107 M-1 s-1, so that reaction with base becomes important only above pH 10. As a result this radical provides an excellent system for studying acid-base equilibration processes in near neutral solutions. Azide ion is shown to be an efficient catalyst which allows the acid-base equilibrium to be examined on the 10-μs time scale. Deprotonation is also catalyzed by the dihydroxybenzoic acid used as the radical source. Analogous studies on 4-carboxy-1,3-benzosemiquinone give the pK/sub a/ as 7.9. In spite of this high pK/sub a/, which indicates the rate constant for spontaneous dissociation of this radical to be > 103 s-1, the rate constant for deprotonation by OH-, 4.9 X 108 M-1 s-1, is considerably higher than in the case of 3-carboxy-1,4-benzosemiquinone

  12. Matrix isolation of free radicals from myo-inositol formed by H. reaction in acidic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Krieger, J.; Huettermann, J. (Regensburg Univ. (Germany, F.R.). Inst. fuer Biophysik und Physikalische Biochemie)

    1983-08-01

    Reaction of H radical-atoms produced photolytically in acid glasses with myo-inositol initially results in the formation of three different radical intermediates, two of which give rise to discernable hyperfine interactions in electron spin-resonance spectra whereas one is a non-specific singlet. The two former species correspond to loss of H radicals from all carbon-positions of the polyalcohol. Both intermediates transform into the same secondary radical upon thermal annealing by water elimination.

  13. Pulse radiolysis studies on reactions of ?-hydroxyalkyl radicals with nicotinamide and 6-methyl nicotinic acid

    International Nuclear Information System (INIS)

    Reactions of ?-hydroxyalkyl radicals derived from 2-propanol, ethanol and methanol with nicotinamide (NICAM) and 6-methyl nicotinic acid (6-MNA) were studied at various pHs using pulse radiolysis technique. It is found that ?-hydroxyalkyl radicals react with NICAM and 6-MNA at pHs when nitrogen is in the protonated state. In these reactions, radical adducts of NICAM/6-MNA with ?-hydroxyalkyl radicals are formed which have absorption maxima at about 340–350 nm which subsequently decay to give pyridinyl type of radicals of NICAM and 6-MNA having ?max at 410 nm. Rate constants for the reactions of (CH3)2C·OH, CH3C·HOH and ·CH2OH radicals with NICAM and 6-MNA were found to have linear dependence on reduction potentials of corresponding ?-hydroxyalkyl radicals. Adducts formed in the reactions of CH3C·HOH and ·CH2OH radicals with both NICAM and 6-MNA decayed slowly compared to the decay of adduct formed in reactions with (CH3)2C·OH radicals. - Highlights: ? Adduct formation in the reactions of ?-hydroxyalkyl radicals with nicotinamide and 6-methyl nicotinic acid was studied by pulse radiolysis technique. ? Adducts undergo decay to give pyridinyl type of radicals of nicotinamide and 6-methyl nicotinic acid. ? Linear dependence of adduct formation rate constants on reduction potential of reducing radicals is seen.

  14. Reactions of linoleic acid peroxyl radicals with phenolic antioxidants: a pulse radiolysis study

    International Nuclear Information System (INIS)

    Linoleic acid peroxyl radicals (LOO) can be viewed as model intermediates occurring during lipid peroxidation processes. Formation and reactions of these species were investigated in aqueous alkaline solution using pulse radiolysis combined with kinetic spectroscopy. Irradiation of linoleic acid in N2O/O2-saturated solutions leads to a mixture of peroxyl radical isomers; reaction of 13-hydroperoxylinoleic acid (13-LOOH) with azide radicals in N2O-saturated solution produces 13-LOO radicals specifically. These peroxyl radicals cannot be observed directly, but their reactions with kaempferol and quercetin, acting as radical-scavenging antioxidants, produced strongly absorbing aroxyl radicals (ArO). The same aroxyl radicals were generated by OH and N3 with rate constants exceeding 109 dm3 mol-1 s-1. Applying a reaction scheme that includes competing generation and decay reactions of both LOO and ArO radicals, individual rate constants were derived for LOO reactions with the phenols (> 107 dm3 mol-1 s-?1), with aroxyl radicals to form covalent adducts (> 108 dm3 mol-1 s-1), as well as for their bimilecular decay (3.0 x 108 dm3 mol-1 s-1). These results demonstrate high reactivity of fatty acid peroxyl radicals and flavone antioxidants in aqueous solution. (author)

  15. EPR study of gamma induced radicals in amino and iminodiacetic acid derivatives

    Scientific Electronic Library Online (English)

    Murat, Aydin; M. Halim, Baskan; M. Y., Emre Osmanoglu.

    2009-09-01

    Full Text Available In this study, electron paramagnetic resonance spectroscopy was used to investigate free radicals formed in gamma irradiated L-glutamine hydrochloride, iminodiacetic acid hydrochloride and N-(2-hyroxyethyl) iminodiacetic acid powders. The free radicals produced in L-glutamine hydrochloride powders w [...] ere attributed to the CH2CHCOOH radical; and those in iminodiacetic acid hydrochloride and N-(2-hyroxyethyl) iminodiacetic acid powders to the HNCHCH2(COOH)2 and HOCH2CH2NCHCH2(COOH)2, respectively. The g-values of the radicals and the hyperfine structure constants of the free electron with the environmental protons and 14N nucleus were determined. The samples were not displayed before they were not irradiated. The free radicals were found stable at room temperature for more than six months. Some spectroscopic properties and suggestions concerning possible structure of the radicals are discussed in this paper.

  16. Unexpected reactivity of amidogen radical in the gas phase degradation of nitric acid.

    Science.gov (United States)

    Anglada, Josep M; Olivella, Santiago; Solé, Albert

    2014-05-14

    The gas phase reaction between nitric acid and amidogen radical has been investigated employing high level quantun-mechanical electronic structure methods and variational transition state theory kinetic calculations. Our results show that the reaction proceeds through a proton coupled electron transfer mechanism with a rate constant of 1.81 × 10(-13) cm(3)·molecule(-1)·s(-1) at 298 K. This value is similar to the rate constants for the reactions of hydroxyl radical with either ammonia or nitric acid. An analysis of these data in the context of the chemistry of the atmosphere suggests that the amidogen radical, formed in the oxidation of ammonia by hydroxyl radical, reacts with nitric acid regenerating ammonia. On the basis of these findings, we propose a potential new catalytic-like cycle which couples the oxidation of ammonia by hydroxyl radical and the reaction of nitric acid with amidogen radical in the Earth's atmosphere. PMID:24792039

  17. Comparative Evaluation of the Radical-Scavenging Activities of Fucoxanthin and Its Stereoisomers

    OpenAIRE

    Yiping Zhang; Hua Fang; Quanling Xie; Jipeng Sun; Rui Liu; Zhuan Hong; Ruizao Yi; Hao Wu

    2014-01-01

    Fucoxanthin (Fuco) is a characteristic carotenoid of brown seaweeds. In the present study, Fuco and its stereoisomers 9'Z-Fuco, 13Z- and 13'Z-Fuco were extracted from Laminaria japonica Aresch. They were isolated and purified by silica gel column chromatography, Sephadex LH-20, and reversed-phase HPLC. The radical-scavenging activities of the three stereoisomers were evaluated toward 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, 2-2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) ra...

  18. Reactions of thiyl radicals from thiols and disulphides with antioxidants. A pulse radiolytic study (Preprint No. RC-5)

    International Nuclear Information System (INIS)

    Absolute rate constants for the reactions of thiyl radicals generated from a variety of thiols and disulphides with 2,2'-azino bis-(3-ethyl-benzthiazoline-6-sulphonate) (ABTS) and ascorbic acid (AH-) using pulse radiolysis technique have been evaluated. (author). 3 refs

  19. Reactivity of phenolic compounds towards free radicals under in vitro conditions.

    Science.gov (United States)

    Mathew, Sindhu; Abraham, T Emilia; Zakaria, Zainul Akmar

    2015-09-01

    The free radical scavenging activity and reducing power of 16 phenolic compounds including four hydroxycinnamic acid derivatives namely ferulic acid, caffeic acid, sinapic acid and p-coumaric acid, benzoic acid and its derivatives namely protocatechuic acid, gallic acid and vanillic acid, benzene derivatives namely vanillin, vanillyl alcohol, veratryl alcohol, veratraldehyde, pyrogallol, guaiacol and two synthetic antioxidants, butylated hydroxy anisole (BHA) and propyl gallate were evaluated using 1,1-Diphenyl-2-picrylhydrazyl radical (DPPH(•)), 2,2'-Azinobis-3- ethylbenzothiazoline-6-sulfonic acid radical (ABTS(+•)), Hydroxyl radical ((•)OH) and Superoxide radical (O2 (•-)) scavenging assays and reduction potential assay. By virtue of their hydrogen donating ability, phenolic compounds with multiple hydroxyl groups such as protocatechuic acid, pyrogallol, caffeic acid, gallic acid and propyl gallate exhibited higher free radical scavenging activity especially against DPPH(•) and O2 (•-). The hydroxylated cinnamates such as ferulic acid and caffeic acid were in general better scavengers than their benzoic acid counter parts such as vanillic acid and protocatechuic acid. All the phenolic compounds tested exhibited more than 85 % scavenging due to the high reactivity of the hydroxyl radical. Phenolic compounds with multiple hydroxyl groups also exhibited high redox potential. Exploring the radical scavenging and reducing properties of antioxidants especially those which are found naturally in plant sources are of great interest due to their protective roles in biological systems. PMID:26344993

  20. Mechanism and kinetics in reactions of caffeic acid with radicals by pulse radiolysis and calculation

    International Nuclear Information System (INIS)

    The interaction of caffeic acid with eaq-, (CH3)2(OH) CCH2·, CO2·-, H·, ·OH and N3· radicals were studied by ?-, pulse radiolysis and molecular orbital calculation. UV-visible spectra of electron/·OH adducts, semi-quinone radicals of caffeic ions, and the stable products from the reactions were derived. The rate constants were determined. The attacked sites and the most favorable structures of the transient radicals were predicted. Reaction mechanisms were proposed. (author)

  1. Hydroxyl radical modify amino acids and prevent E. coli growth

    International Nuclear Information System (INIS)

    The authors report that hydroxyl radical (/sup ./OH) damage to amino acids (AA) affects their incorporation into E. coli proteins. Modification of AA (Try, Trp, Met, Cys, His, Lys, Asn, Gln) by /sup ./OH was achieved by exposure to 60Co radiation (1-100 krads at 600 rads/min) in N2O saturated water. Following exposure to /sup ./OH, the modified AA were added to suspensions of 8 AA requiring E. coli mutants in M9 medium + glucose. Mutants incubated with the /sup ./OH modified AA underwent less growth than those incubated with unmodified AA; with a declining exponential relationship between /sup ./OH exposure of AA and cell growth. The sensitivity of each AA to modification by /sup ./OH was as follows: Tyr > Trp > Met > Cys > His > Lys > Asn > Gln. Essentially the same pattern was observed for inhibition of mutant growth, which was proportional to the concentration of remaining unmodified (i.e. native) AA. Furthermore, cell growth was restored to normal levels by replenishment of native AA. When AA were irradiated at 50?M and then diluted to concentrations expected to support exponential growth (different for each AA) the radiation doses at which mutant growth was inhibited by 63% were as follows (in krad): Tyr 41, Trp 48, Met 53, Cys 56, His 57, Lys 68, Asn 80, Gln 116. /sup ./OH-modified 3H-Trp was not a substrate for protein synthesis in Trp requiring mutants but was taken up by the cells. Modified Trp was also not incorporated in cell-free synthesis experiments. No toxicity was observed when wild type E. coli, in M9 medium + glucose, were supplemented with any of the/sup ./OH-modified AA. Thus /sup ./OH-modified AA do not support E. coli growth

  2. Evaluation of the Antiradical Properties of Phenolic Acids

    Directory of Open Access Journals (Sweden)

    Olga Koroleva

    2014-09-01

    Full Text Available Antioxidant capacity (AOC against peroxyl radical and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid diammonium salt (ABTS radical cation was measured for a series of p-hydroxybenzoic (HB and p-hydroxycinnamic (HC acids at different pH. Quantum-chemical computation was performed using Gaussian 3.0 software package to calculate the geometry and energy parameters of the same compounds. Significant correlations were revealed between AOC and a number of calculated parameters. The most significant AOC descriptors for the studied compounds against peroxyl radical were found to be HOMO energy, rigidity (? and Mulliken charge on the carbon atom in m-position to the phenolic hydroxyl. The most significant descriptor of the antioxidant properties against the ABTS radical cation at ?? 7.40 is electron transfer enthalpy from the phenolate ion. The mechanism of AOC realization has been proposed for HB and HC acids against both radicals.

  3. Electrochemical examination of the ascorbic acid radical anion in non-aqueous electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Yoshimura, M.; Honda, K.; Kondo, T.; Rao, T.N.; Tryk, D.A.; Fujishima, A

    2002-10-15

    A quasi-reversible redox reaction involving ascorbic acid was observed in non-aqueous electrolytes at conductive diamond electrode. The chemical reversibility of these reactions is consistent with ascorbic acid being reduced to the ascorbic acid radical anion in a one-electron process, with subsequent reoxidation to ascorbic acid. This is the first report on the electrochemical production of the ascorbic acid radical anion in non-aqueous electrolytes. Ascorbyl 6-stearate and 4-hydroxy 2(5H)-furanone, which have somewhat similar structures as ascorbic acid, also showed one-electron transfer reduction reaction producing radicals with a single negative charge, suggesting that these compounds follow the same electrochemical behavior as ascorbic acid. The double bond and hydroxyl substituent on the five-membered ring are shown to be necessary for the stabilization of the radical anions. It was confirmed by the calculation of the total energy using molecular orbital methods that resonance structures involving the double-bond and hydroxyl group provide significant stabilization of the radical anions. Electrochemical preparation may be a useful method for the detailed study of radicals, their molecular structure and reactivity.

  4. Electrochemical examination of the ascorbic acid radical anion in non-aqueous electrolytes

    International Nuclear Information System (INIS)

    A quasi-reversible redox reaction involving ascorbic acid was observed in non-aqueous electrolytes at conductive diamond electrode. The chemical reversibility of these reactions is consistent with ascorbic acid being reduced to the ascorbic acid radical anion in a one-electron process, with subsequent reoxidation to ascorbic acid. This is the first report on the electrochemical production of the ascorbic acid radical anion in non-aqueous electrolytes. Ascorbyl 6-stearate and 4-hydroxy 2(5H)-furanone, which have somewhat similar structures as ascorbic acid, also showed one-electron transfer reduction reaction producing radicals with a single negative charge, suggesting that these compounds follow the same electrochemical behavior as ascorbic acid. The double bond and hydroxyl substituent on the five-membered ring are shown to be necessary for the stabilization of the radical anions. It was confirmed by the calculation of the total energy using molecular orbital methods that resonance structures involving the double-bond and hydroxyl group provide significant stabilization of the radical anions. Electrochemical preparation may be a useful method for the detailed study of radicals, their molecular structure and reactivity

  5. Free radicals in dicarboxylic acids: an e.s.r. study of radical conversions in ?-irradiated single crystals of glutaric acid and glutaric-2,2,4,4-d4 acid

    International Nuclear Information System (INIS)

    The ?-radiation-induced free radicals in single crystals of glutaric acid and glutaric-2,2,4,4-d4 acid were studied in the temperature range 77-300 K by e.s.r. techniques. At 77 K the decarboxylation radical and the anion are stabilized. At higher temperatures the decarboxylation radical is found to be converted into a hydrogen abstraction radical with an activation energy of 6.3 +- 0.5 kcal/mole for the non-deuterated crystal. This radical is stable at room temperature. The anion seems to be converted to a unidentified intermediate radical which in turn is converted to the ?-acyl radical. An analysis of the g-value anisotropy and of the 13C hyperfine splitting variation for this radical in the deuterated crystal is consistent with the assigned radical structure. By heat treatment the ?-acyl radical is converted to another form of the hydrogen abstraction radical with an activation energy of 9.6 +- 0.6 kcal/mole in the deuterated crystal. U.V.-light (lambda= 254 nm) transforms one of the room temperature radicals into the other. (author)

  6. Free-radical redox reactions of uranium ions in sulphuric acid solutions

    International Nuclear Information System (INIS)

    The radiolytic reduction of uranyl ions in degassed sulphuric acid solutions containing various organic solutes was studied. It was shown that while COOH, CO2-, and ?-hydroxyl-alkyl radicals reduced uranyl ions, the ?-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

  7. Determination of hyperfine constants for the RCONHO radical in randomly oriented samples of x-irradiated hydroxamic acids

    International Nuclear Information System (INIS)

    RCONHO radicals are identified in x-irradiated acetohydroxamic acid, hydroxyurethane, and propiohydroxamic acid. The hydrogen and nitrogen hyperfine coupling constants for these radicals are evaluated from ESR spectra taken of polycrystalline samples. The characteristic spectrum of randomly oriented RCONHO radicals is described. Equations for the coupling constants in terms of the width of the spectrum are given

  8. A determination of hyperfine constants for the RCONHO radical in randomly oriented samples of x-irradiated hydroxamic acids

    Science.gov (United States)

    Shields, Howard; de Lyon, Terence; Chiu, Fonjen; Hamrick, Phillip J., Jr.

    1982-11-01

    RCONHO radicals are identified in x-irradiated acetohydroxamic acid, hydroxyurethane, and propiohydroxamic acid. The hydrogen and nitrogen hyperfine coupling constants for these radicals are evaluated from ESR spectra taken of polycrystalline samples. The characteristic spectrum of randomly oriented RCONHO radicals is described. Equations for the coupling constants in terms of the width of the spectrum are given.

  9. Free radicals during hypertriglyceridemia treatment by N-3 fatty acids.

    Czech Academy of Sciences Publication Activity Database

    Zeman, M.; Stopka, Pavel; Vecka, M.; Žák, A.

    2006-01-01

    Ro?. 7, ?. 3 (2006), s. 292. ISSN 1567-5688 R&D Projects: GA MZd NR8806 Institutional research plan: CEZ:AV0Z40320502 Keywords : free radicals Subject RIV: CA - Inorganic Chemistry Impact factor: 5.875, year: 2006

  10. Free radicals in dicarboxylic acids: an e.s.r. study of ?-irradiated single crystals of glutaric acid at 77 K

    International Nuclear Information System (INIS)

    Electron spin resonance techniques were used to study the ?-radiation-induced free radicals in single crystals of glutaric acid in the temperature range from 77 K to 300 K. Three different radicals are stabilized at 77 K. The decarboxylation radical is the dominant species and the other two radicals are assigned to the anion and to the substituted acetyl ?-radical. When the temperature of the crystal was raised, these radicals disappeared and the previously studied room temperature radicals appeared. E.S.R.-data and the results from semi-empirical INDO-MO calculations were compared in order to elucidate the structures of the various radicals. (author)

  11. Pulse radiolysis studies on reactions of ?-hydroxyalkyl radicals with nicotinamide and 6-methyl nicotinic acid

    Science.gov (United States)

    Dhiman, S. B.; Naik, D. B.

    2012-06-01

    Reactions of ?-hydroxyalkyl radicals derived from 2-propanol, ethanol and methanol with nicotinamide (NICAM) and 6-methyl nicotinic acid (6-MNA) were studied at various pHs using pulse radiolysis technique. It is found that ?-hydroxyalkyl radicals react with NICAM and 6-MNA at pHs when nitrogen is in the protonated state. In these reactions, radical adducts of NICAM/6-MNA with ?-hydroxyalkyl radicals are formed which have absorption maxima at about 340-350 nm which subsequently decay to give pyridinyl type of radicals of NICAM and 6-MNA having ?max at 410 nm. Rate constants for the reactions of (CH3)2Crad OH, CH3Crad HOH and rad CH2OH radicals with NICAM and 6-MNA were found to have linear dependence on reduction potentials of corresponding ?-hydroxyalkyl radicals. Adducts formed in the reactions of CH3Crad HOH and rad CH2OH radicals with both NICAM and 6-MNA decayed slowly compared to the decay of adduct formed in reactions with (CH3)2Crad OH radicals.

  12. Evaluation of the Antiradical Properties of Phenolic Acids

    OpenAIRE

    Olga Koroleva; Anna Torkova; Ilya Nikolaev; Ekaterina Khrameeva; Tatyana Fedorova; Mikhail Tsentalovich; Ryszard Amarowicz

    2014-01-01

    Antioxidant capacity (AOC) against peroxyl radical and 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) radical cation was measured for a series of p-hydroxybenzoic (HB) and p-hydroxycinnamic (HC) acids at different pH. Quantum-chemical computation was performed using Gaussian 3.0 software package to calculate the geometry and energy parameters of the same compounds. Significant correlations were revealed between AOC and a number of calculated parameters. The mo...

  13. Picosecond Pulse Radiolysis of Highly Concentrated Phosphoric Acid Solutions: Mechanism of Phosphate Radical Formation.

    Science.gov (United States)

    Ma, Jun; Schmidhammer, Uli; Mostafavi, Mehran

    2015-06-18

    Eight solutions containing phosphoric acid with concentrations ranging from 2 mol L(-1) to neat acid have been studied by picosecond pulse radiolysis. The absorbance of the secondary radical H2PO4(•) formed within 7 ps of the electron pulse is observed using pulse-probe method in the visible. Kinetic analysis shows that the radicals of phosphoric acid are formed via two mechanisms: direct electron detachment and oxidation by the radical cation of water, H2O(•+). On the basis of molar extinction coefficient value of 1850 L mol(-1) cm(-1), at 15 ps the radiolytic yield of H2PO4(•) formation by direct energy absorption is 3.7 ± 0.1 × 10(-7) mol J(-1) in neat phosphoric acid. In highly concentrated phosphoric acid solutions, the total yield of phosphate radical at 15 ps exhibits an additional contribution that can be explained by electron transfer from phosphoric acid to H2O(•+). The efficiency of the electron transfer to this strongly oxidizing species in phosphoric acid solutions is lower compared with the one in sulfuric acid solutions. Two explanations are given to account for a relatively low efficiency of H2O(•+) scavenging in concentrated phosphoric acid solutions. PMID:25176139

  14. ANTIOXIDANT PROPERTIES OF LIGNANS AND FERULIC ACID FROM THE RESINOUS EXUDATE OF LARREA NITIDA

    OpenAIRE

    RENÉ TORRES; FRANCISCO URBINA; CLAUDIA MORALES; BRENDA MODAK; FRANCO DELLE MONACHE

    2003-01-01

    From the resinous exudate of twigs end leaves of Larrea nitida, two lignans nor isoguaiacine 1 and meso-nor-dihydroguaiaretic acid 2 and ferulic acid 3 were isolated. The antioxidant activities of resin and pure compounds were assesed by bleaching of the ABTS derived radical-cation

  15. ANTIOXIDANT PROPERTIES OF LIGNANS AND FERULIC ACID FROM THE RESINOUS EXUDATE OF LARREA NITIDA

    Directory of Open Access Journals (Sweden)

    RENÉ TORRES

    2003-09-01

    Full Text Available From the resinous exudate of twigs end leaves of Larrea nitida, two lignans nor isoguaiacine 1 and meso-nor-dihydroguaiaretic acid 2 and ferulic acid 3 were isolated. The antioxidant activities of resin and pure compounds were assesed by bleaching of the ABTS derived radical-cation

  16. ANTIOXIDANT PROPERTIES OF LIGNANS AND FERULIC ACID FROM THE RESINOUS EXUDATE OF LARREA NITIDA

    Scientific Electronic Library Online (English)

    RENÉ, TORRES; FRANCISCO, URBINA; CLAUDIA, MORALES; BRENDA, MODAK; FRANCO DELLE, MONACHE.

    2003-09-01

    Full Text Available From the resinous exudate of twigs end leaves of Larrea nitida, two lignans nor isoguaiacine 1 and meso-nor-dihydroguaiaretic acid 2 and ferulic acid 3 were isolated. The antioxidant activities of resin and pure compounds were assesed by bleaching of the ABTS derived radical-cation [...

  17. Reaction of thiyl radicals with alcohols, ethers and polyunsaturated fatty acids: A possible role of thiyl free radicals in thiol mutagenesis?

    International Nuclear Information System (INIS)

    Possible reactions of thiyl free radicals in biological environment are reviewed. In particular hydrogen transfer processes from model C-H compounds like alcohols and ethers as well as from polyunsaturated fatty acids to thiyl radicals are described to proceed with reasonably high rate constants (103-104 and 106-107 M-1 s-1, respectively). Thiyl radicals have thus to be considered as potentially hazardous species especially with respect to DNA damage and lipid peroxidation. (orig.)

  18. Identification of free radicals induced by gamma irradiation in amino acid derivatives

    Scientific Electronic Library Online (English)

    Murat, Aydin.

    2010-09-01

    Full Text Available Powders of N- acetyl- L- leucine and N- methyl- L- glutamic acid were gamma irradiated and the free radicals formed were investigated at room temperature by electron paramagnetic resonance technique. The free radicals formed in compounds were attributed to the (CH3)2CCH2CH(NHCOCH3)COOH and HOOCCH2CH [...] 2C (NHCH3)COOH radicals respectively. Both radicals are very stable and we could observe them for five months without almost intensity diminution at room temperature. The g values of the radicals and the hyperfine structure constants of the free electron with nearby protons and 14N nucleus were determined. The results were found to be in good agreement with the existing literature data.

  19. Study of the structure of free radicals in gamma: irradiated amino acid derivatives

    Scientific Electronic Library Online (English)

    Murat, Aydin.

    2010-12-01

    Full Text Available Electron paramagnetic resonance spectroscopy has been used for the study of the free radicals produced in the powders of L-arginine monohydrochloride, ala-ala and DL-?-leucine gamma-irradiated at room temperature. The structures of the radicals formed in compounds were determined as NH2(NH)NHCHCH2CH [...] 2CH(NH2)COOH, CH3CHCOOH and (CH3)2C CH(NH2)CH2COOH respectively. The paramagnetic species were found to be stable at room temperature more than three months. It was determined that unpaired electron interacted with nearby protons and 14N nucleus in these radicals. The g values of the radicals and the hyperfine structure constants of the free electron were also measured. These results were compared with the earlier studies in amino acid and derivatives radicals and discussed.

  20. Free Radicals, Salicylic Acid and Mycotoxins in Asparagus After Inoculation with Fusarium proliferatum and F. oxysporum.

    Science.gov (United States)

    Dobosz, Bernadeta; Drzewiecka, Kinga; Waskiewicz, Agnieszka; Irzykowska, Lidia; Bocianowski, Jan; Karolewski, Zbigniew; Kostecki, Marian; Kruczynski, Zdzislaw; Krzyminiewski, Ryszard; Weber, Zbigniew; Golinski, Piotr

    2011-09-01

    Electron paramagnetic resonance was used to monitor free radicals and paramagnetic species like Fe, Mn, Cu generation, stability and status in Asparagus officinalis infected by common pathogens Fusarium proliferatum and F. oxysporum. Occurrence of F. proliferatum and F. oxysporum, level of free radicals and other paramagnetic species, as well as salicylic acid and mycotoxins content in roots and stems of seedlings were estimated on the second and fourth week after inoculation. In the first term free and total salicylic acid contents were related to free radicals level in stem (P = 0.010 and P = 0.033, respectively). Concentration of Fe(3+) ions in porphyrin complexes (g = 2.3, g = 2.9) was related to the species of pathogen. There was no significant difference between Mn(2+) concentrations in stem samples; however, the level of free radicals in samples inoculated with F. proliferatum was significantly higher when compared to F. oxysporum. PMID:21957331

  1. Diagnosis of hydroxyl radicals and the treatment of Acid Orange ? in negative pulsed discharge

    International Nuclear Information System (INIS)

    A kind of device supplied with negative pulsed high voltage was designed for water treatment. The nozzle discharge electrode was supplied with high voltage and the cylinder wall of the treatment chamber was grounded. Since the non-thermal plasma, especially, hydroxyl radicals played the dominant role in removing pollutants in the water by discharge plasma, hydroxyl radicals were measured in the negative pulsed discharge process by the optical emission spectroscopy (OES) effects of the repetition rate and the peak value of the pulsed discharge on the hydroxyl radicals' production and the decomposition rate of the Acid Orange ? solution were studied.

  2. Matrix isolation of free radicals from myo-inositol formed by H. reaction in acidic glasses

    International Nuclear Information System (INIS)

    Reaction of Hradical-atoms produced photolytically in acid glasses with myo-inositol initially results in the formation of three different radical intermediates, two of which give rise to discernable hyperfine interactions in electron spin-resonance spectra whereas one is a non-specific singlet. The two former species correspond to loss of Hradicals from all carbon-positions of the polyalcohol. Both intermediates transform into the same secondary radical upon thermal annealing by water elimination. (author)

  3. Free radical initiation in proteins and amino acids by ionizing and ultraviolet radiations and lipid oxidation. Part III: free radical transfer from oxidizing lipids

    International Nuclear Information System (INIS)

    Parallels and similarities in chemical and functional damage to proteins by ionizing and uv radiations and oxidizing lipids have been recognized for some time. However, only recently have oxidizing lipids been shown directly by electron spin resonance to be radiomimetic also in their capacity for protein free radical production. Accordingly, this review is a detailed comparison of gamma-radiation, uv radiation, and lipid oxidation for what is presently known concerning (1) the specific modes of energy deposition and free radical formation, (2) the free radicals formed in proteins and amino acids, and (3) the typical damage correlating with these radicals

  4. E.s.r. of spin-trapped radicals in ?-irradiated polycrystalline amino acids, N-acetyl amino acids and dipeptides

    International Nuclear Information System (INIS)

    The radicals produced in several polycrystalline amino acids, N-acetyl amino acids and dipeptides by ?-radiolysis at room temperature were investigated by spin-trapping. After irradiation in the solid state, the samples were dissolved in aqueous solutions of t-nitrosobutane and the trapped radicals identified by e.s.r. For ?-amino acids, deamination radicals were found, and in some cases H-abstraction radicals were also observed. No decarboxylation radicals could be detected. For N-acetyl amino acids, except for N-acetylglycine, the major radical was the decarboxylation radical. For N-acetylglycine the H-abstraction radical from the glycine residue was observed. For dipeptides of the type x-glycine, the radical formed by removal of H from the ?-carbon of the carboxyl-terminal residue was always spin-trapped. Some primary deamination radicals and minor amounts of decarboxylation radicals could also be observed. For dipeptides of the type x-alanine, glycine-x and alanine-x, the decarboxylation radical was always the major spin-trapped radical. Some primary and secondary deamination radicals were also detected. (author)

  5. OH-radical induced degradation of hydroxybenzoic- and hydroxycinnamic acids and formation of aromatic products—A gamma radiolysis study

    Science.gov (United States)

    Krimmel, Birgit; Swoboda, Friederike; Solar, Sonja; Reznicek, Gottfried

    2010-12-01

    The OH-radical induced degradation of hydroxybenzoic acids (HBA), hydroxycinnamic acids (HCiA) and methoxylated derivatives, as well as of chlorogenic acid and rosmarinic acid was studied by gamma radiolysis in aerated aqueous solutions. Primary aromatic products resulting from an OH-radical attachment to the ring (hydroxylation), to the position occupied by the methoxyl group (replacement -OCH 3 by -OH) as well as to the propenoic acid side chain of the cinnamic acids (benzaldehyde formations) were analysed by HPLC-UV and LC-ESI-MS. A comparison of the extent of these processes is given for 3,4-dihydroxybenzoic acid, vanillic acid, isovanillic acid, syringic acid, cinnamic acid, 4-hydroxycinnamic acid, caffeic acid, ferulic acid, isoferulic acid, chlorogenic acid, and rosmarinic acid. For all cinnamic acids and derivatives benzaldehydes were significant oxidation products. With the release of caffeic acid from chlorogenic acid the cleavage of a phenolic glycoside could be demonstrated. Reaction mechanisms are discussed.

  6. OH-radical induced degradation of hydroxybenzoic- and hydroxycinnamic acids and formation of aromatic products-A gamma radiolysis study

    Energy Technology Data Exchange (ETDEWEB)

    Krimmel, Birgit; Swoboda, Friederike [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology (Austria); Solar, Sonja, E-mail: sonja.solar@univie.ac.a [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology (Austria); Reznicek, Gottfried [Department of Pharmacognosy, Althanstrasse 14, A-1090 Vienna (Austria)

    2010-12-15

    The OH-radical induced degradation of hydroxybenzoic acids (HBA), hydroxycinnamic acids (HCiA) and methoxylated derivatives, as well as of chlorogenic acid and rosmarinic acid was studied by gamma radiolysis in aerated aqueous solutions. Primary aromatic products resulting from an OH-radical attachment to the ring (hydroxylation), to the position occupied by the methoxyl group (replacement -OCH{sub 3} by -OH) as well as to the propenoic acid side chain of the cinnamic acids (benzaldehyde formations) were analysed by HPLC-UV and LC-ESI-MS. A comparison of the extent of these processes is given for 3,4-dihydroxybenzoic acid, vanillic acid, isovanillic acid, syringic acid, cinnamic acid, 4-hydroxycinnamic acid, caffeic acid, ferulic acid, isoferulic acid, chlorogenic acid, and rosmarinic acid. For all cinnamic acids and derivatives benzaldehydes were significant oxidation products. With the release of caffeic acid from chlorogenic acid the cleavage of a phenolic glycoside could be demonstrated. Reaction mechanisms are discussed.

  7. Antioxidative properties of tronchuda cabbage (Brassica oleracea L. var. costata DC) external leaves against DPPH, superoxide radical, hydroxyl radical and hypochlorous acid

    OpenAIRE

    Vrchovska, V.; de Sousa, C; Valentão, P.; Ferreres, F; J. A. Pereira; Seabra, R.M.; P. B. Andrade

    2006-01-01

    The ability of the aqueous extract of tronchuda cabbage (Brassica oleracea L. var. costata DC) external leaves to act as a scavenger of DPPH- and reactive oxygen species (superoxide radical, hydroxyl radical and hypochlorous acid) was investigated. A phytochemical study was also undertaken, and thirteen phenolic compounds and five organic acids were identified and quantified. Tronchuda cabbage extracts exhibited antioxidant capacity in a concentration-dependent manner in all assays, ...

  8. Structural Insights into 2,2?-Azino-Bis(3-Ethylbenzothiazoline-6-Sulfonic Acid) (ABTS)-Mediated Degradation of Reactive Blue 21 by Engineered Cyathus bulleri Laccase and Characterization of Degradation Products

    OpenAIRE

    Kenzom, T.; Srivastava, P; Mishra, S.

    2014-01-01

    Advanced oxidation processes are currently used for the treatment of different reactive dyes which involve use of toxic catalysts. Peroxidases are reported to be effective on such dyes and require hydrogen peroxide and/or metal ions. Cyathus bulleri laccase, expressed in Pichia pastoris, catalyzes efficient degradation (78 to 85%) of reactive azo dyes (reactive black 5, reactive orange 16, and reactive red 198) in the presence of synthetic mediator ABTS [2,2?-azino-bis(3-ethylbenzothiazoline-...

  9. Spectral and kinetic characteristics of the ?-propionic acid methyl ester radical in cyclohexane and water

    International Nuclear Information System (INIS)

    The ?-propionic acid methyl ester radical was produced in dissociative electron capture reaction of 2-chloropropionic acid methyl ester. The absorption maxima of the radical are at 310 and 300 nm in cyclohexane and water with extinction coefficients of 440±50 and 400±50 mol-1 dm3 cm-1. The second order decay rate parameter in water is (2.3±0.5)x109 mol-1 dm3 s-1. The peroxy radicals have the characteristics: ?max=265-270 nm, ?max=700-900 mol-1 dm3 cm-1 and 2k = (7±2) x 108 mol-1 dm3 s-1. (author) 6 refs.; 4 figs.; 1 tab

  10. Biotechnological treatment for colorless denim and textil wastewater treatment with laccase and ABTS / Tratamiento biotecnológico para la decoloración de la mezclilla y efluentes textiles empleando lacasa y ABTS

    Scientific Electronic Library Online (English)

    Myrna, SOLÍS-OBA; Javier, ALMENDÁRIZ; Gustavo, VINIEGRA-GONZÁLEZ.

    2008-03-01

    Full Text Available El sistema ABTS (ácido 2,2'-[3-etil benzotiazolin-6-sulfónico])-lacasa se empleó para decolorar tanto tela de mezclilla como una solución preparada de índigo. Después del tratamiento, la mezclilla adquirió un aspecto de usada, sin que las fibras mostraran evidencia de daño, mientras que la solución [...] de índigo se decoloró. Adicionalmente, el análisis de la biodegradación de los desechos acuosos de la decoloración de la mezclilla y la solución decolorada control de índigo mostraron que, en ambos casos el agua residual fue fácilmente biodegradada tanto aeróbica como anaeróbicamente, mientras que la solución control de índigo requirió de 5 días para biodegradarse aeróbicamente y no sufrió ningún cambio en el sistema anaeróbico. El ABTS oxidado ó la lacasa por sí solos no decoloraron la mezclilla ni la solución de índigo bajo las mismas condiciones experimentales en que se empleó la combinación de ambos ABTS-lacasa. Esto se explica porque, durante la reacción de decoloración, el mediador se recicla varias veces entre la enzima y el colorante, de tal forma que en 30 minutos, una molécula de ABTS oxida 800 moléculas de índigo, además la velocidad de decoloración fue dos órdenes de magnitud mayor que la velocidad cuando se empleó el ABTS ó la enzima en forma individual. Abstract in english The ABTS (2,2'-[3-etil benzotiazolin-6-sulphonic]acid)-Laccase system was applied for discoloration of both commercial denim fabric and a synthetic indigo solution. After treatment, the denim fabric looked like an aged one, although fibers did not exhibit any damage and the synthetic indigo solution [...] was bleached. Additionally, an analysis of both the denim discoloration residual water and the synthetic indigo solution biodegradation, showed that in the two cases the residual water was easily biodegraded in either an aerobic or anaerobic mode, while the control indigo solution required 5 days to be biodegraded in an aerobic mode, and it became unaltered in anaerobic mode. The oxidized ABTS or the laccase could not bleach denim or the synthetic indigo solution in the same experimental conditions as when using the system ABTS-laccase. This is explained considering that, during this process, as when using the mediator recycles several times between the laccase and the indigo, in such way that in a 30 min period, one molecule of ABTS oxidized 800 indigo molecules; also, the observed discoloration rate was two orders of magnitude higher than the rates observed when either the oxidized mediator or the enzyme by itself were applied.

  11. Radical Scavenging Capacity of Methanolic Phillyrea latifolia L. Extract: Anthocyanin and Phenolic Acids Composition of Fruits

    Directory of Open Access Journals (Sweden)

    Naciye Erkan

    2013-01-01

    Full Text Available Radical scavenging capacity of a crude methanolic extract from the fruits of Phillyrea latifolia L., commonly known as green olive tree or mock privet, was investigated with reference to anthocyanin standards, as flavonoids, and phenolic acid standards, as phenylpropanoids. Characterization with high performance liquid chromatography-diode array detection (HPLC-DAD indicated the presence of keracyanin, kuromanin, cyanidin, ferulic acid, caffeic acid and rosmarinic acid at amounts of 289.1, 90.4, 191.4, 225.2, 221.2 and 190.1 mg/100 g fresh weight (FW of fruits, respectively. Chlorogenic and p-coumaric acids were found to exist in lower amounts. Trolox equivalent antioxidant capacity (TEAC and IC50 values of the plant extract were found to be 1.8 mM Trolox equivalents (TE/g FW of fruits and 69.4 µg/mL, respectively, indicating the close radical scavenging activity of the extract to those of keracyanin and p-coumaric acid. The crude methanolic P. latifolia L. fruit extract was seen to be fairly potent in radical scavenging. Total phenolic content (TPC of the plant extract was found to be 1652.9 mg gallic acid equivalent (GAE/100 g FW of fruits.

  12. Kinetics of free radical decay reactions in lactic acid homo and copolymers irradiated to sterilization dose

    International Nuclear Information System (INIS)

    The kinetics of free radical decay reactions of poly(L-Lactic acid), poly(DL-Lactic acid) and random copolymer of lactic and glycolic acid have been investigated for decays taking place in air and in vacuum. The change in ESR lines of ?-irradiated polymers have been followed over a long time period. The decay has been found to follow neither simple first-order nor second-order kinetics. Various kinetic approaches including composite first or second-order mechanisms and diffusion-controlled first or second-order equations were determined to be also unsatisfactory. The decay of radicals in bulk irradiated lactic acid homo and copolymers was found to be best described when the second-order non-classical equation with time dependent rate constant approach was used. (Author)

  13. Atmospheric chemistry of perfluorinated carboxylic acids: Reaction with OH radicals and atmospheric lifetimes

    DEFF Research Database (Denmark)

    Hurley, MD; Andersen, Mads Peter Sulbæk; Wallington, TJ; Ellis, DA; Martin, JW; Mabury, SA

    2004-01-01

    Relative rate techniques were used to study the kinetics of the reactions of OH radicals with a homologous series of perfluorinated acids, F(CF2)(n)COOH (n = 1, 2, 3, 4), in 700 Torr of air at 296 +/- 2 K. For n > 1, the length of the F(CF2)(n) group had no discernible impact on the reactivity of...

  14. Diastereoselective radical addition to ?-alkyl-?-methylene-?-butyrolactams and the synthesis of a chiral pyroglutamic acid derivative

    Directory of Open Access Journals (Sweden)

    Tomoko Yajima

    2013-07-01

    Full Text Available The cis- and trans-stereoselective radical additions to ?-methylene-?-alkyl- ?-lactams were investigated and the scope and limitation of the reaction were also revealed. This stereoselective radical reaction was used for synthesis of chiral pyroglutamic acid derivatives starting from a commercially available chiral amino acid.

  15. Effect of water and ethanol radicals on the protein part of human hemoglobin. Pt. 2. Damage to amino acid residues

    International Nuclear Information System (INIS)

    This work is devoted to the effect of interactions of water and ethanol radicals with human hemoglobin (Hb) amino acid residues. The OH radicals caused the greatest destruction of human hemoglobin amino acid residues. Among them the most sensitive to irradiation were cysteine tryptophan and histidine residues. (author). 11 refs, 2 tabs

  16. A Comparative Study of the Radical-scavenging Activity of the Phenolcarboxylic Acids Caffeic Acid, p-Coumaric Acid, Chlorogenic Acid and Ferulic Acid, With or Without 2-Mercaptoethanol, a Thiol, Using the Induction Period Method

    Directory of Open Access Journals (Sweden)

    Seiichiro Fujisawa

    2008-10-01

    Full Text Available Phenolcarboxylic acid antioxidants do not act in vivo as radical-scavengers in isolation, but rather together with GSH (glutathione, a coantioxidant, they constitute an intricate antioxidant network. Caffeic acid, p-coumaric acid, ferulic acid and chlorogenic acid with or without 2-mercaptoethanol (ME, as a substitute for GSH, was investigated by the induction period (IP method for polymerization of methyl methacrylate (MMA initiated by thermal decomposition of 2,2'-azobisisobutyronitrile (AIBN, a source of alkyl radicals, R. and benzoyl peroxide (BPO, a source of peroxy radicals, PhCOO. using differential scanning calorimetry (DSC. Upon PhCOO. radical scavenging, the stoichiometric factors (n, number of free radical trapped by one mole of antioxidant for caffeic acid, ferulic acid, p-coumaric acid and chlorogenic acid were 2.4, 1.8, 1.7 and 0.9, whereas upon R. radical scavenging, the corresponding values were 1.3, 1.2, 1.0 and 0.8, respectively. Antioxidants with n values close to 2 suggest the stepwise formation of semiquinone radicals and quinones. By contrast, those with n values close to 1 suggest the formation of dimers after single-electron oxidation, possibly due to recombination of corresponding aryloxy radicals. The ratio of the rate constant of inhibition to that of propagation (kinh/kp declined in the order chlorogenic acid > p-coumaric acid > ferulic acid > caffeic acid. The ratio of the observed IP for the phenolcarboxylic acid/2-mercapto-ethanol (ME mixture (1:1 molar ratio (A to the calculated IP (the simple sum of phenol acid antioxidant and ME (B was investigated. Upon R. scavenging, the caffeic acid or p-coumaric acid/ME mixture was A/B > 1, particularly the former was 1.2, suggesting a synergic effect. By contrast, upon PhCOO. scavenging, the corresponding mixture was A/B < 1, particularly the latter was 0.7, suggesting an antagonistic effect. Upon both radicals scavenging, the A/B for the ferulic acid or chlorogenic acid/ME mixture was approximately 1. The reported beneficial antioxidant, anti-inflammatory and anticancer effects of caffeic acid and p-coumaric acid may be related to their prooxidant-antioxidant balance in the presence of GSH.

  17. Mechanisms leading to oligomers and SOA through aqueous photooxidation: insights from OH radical oxidation of acetic acid and methylglyoxal

    Directory of Open Access Journals (Sweden)

    Y. Tan

    2012-01-01

    Full Text Available Previous experiments have demonstrated that the aqueous OH radical oxidation of methylglyoxal produces low volatility products including pyruvate, oxalate and oligomers. These products are found predominantly in the particle phase in the atmosphere, suggesting that methylglyoxal is a precursor of secondary organic aerosol (SOA. Acetic acid plays a central role in the aqueous oxidation of methylglyoxal and it is a ubiquitous product of gas phase photochemistry, making it a potential "aqueous" SOA precursor in its own right. However, the fate of acetic acid upon aqueous-phase oxidation is not well understood. In this research, acetic acid (20 ?M–10 mM was oxidized by OH radicals, and pyruvic acid and methylglyoxal experimental samples were analyzed using new analytical methods, in order to better understand the formation of SOA from acetic acid and methylglyoxal. Glyoxylic, glycolic, and oxalic acids formed from acetic acid and OH radicals. In contrast to the aqueous OH radical oxidation of methylglyoxal, the aqueous OH radical oxidation of acetic acid did not produce succinic acid and oligomers. This suggests that the methylgloxal-derived oligomers do not form through the acid catalyzed esterification pathway proposed previously. Using results from these experiments, radical mechanisms responsible for oligomer formation from methylglyoxal oxidation in clouds and wet aerosols are proposed. The importance of acetic acid/acetate as an SOA precursor is also discussed. We hypothesize that this and similar chemistry is central to the daytime formation of oligomers in wet aerosols.

  18. Mechanism and kinetics in reactions of caffeic acid with radicals by pulse radiolysis and calculation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xifeng; Cai, Zhongli; Katsumura, Yosuke [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab

    2000-03-01

    The interaction of caffeic acid with e{sub aq}{sup -}, (CH{sub 3}){sub 2}(OH) CCH{sub 2}{sup {center_dot}}, CO{sub 2}{sup {center_dot}}{sup -}, H{sup {center_dot}}, {center_dot}OH and N{sub 3}{sup {center_dot}} radicals were studied by {gamma}-, pulse radiolysis and molecular orbital calculation. UV-visible spectra of electron/{center_dot}OH adducts, semi-quinone radicals of caffeic ions, and the stable products from the reactions were derived. The rate constants were determined. The attacked sites and the most favorable structures of the transient radicals were predicted. Reaction mechanisms were proposed. (author)

  19. The role of oxidizing radicals in neptunium speciation in ?-irradiated nitric acid

    International Nuclear Information System (INIS)

    The irradiation of aqueous nitric acid solutions generates transient, reactive species that are known to oxidize neptunium. However, nitrous acid is also a long-lived product of nitric acid irradiation, which reduces neptunium. When we irradiated nitric acid solutions of neptunium and measured its speciation by UV/Vis spectroscopy, we found that at short irradiation times, oxidation of Np(V) to Np(VI) occurred due to reactions with radicals such as •OH, •NO3 and •NO2. However, at higher absorbed doses and after a sufficient amount of nitrous acid was produced, reduction of Np(VI) to Np(V) began to occur, eventually reaching an equilibrium distribution of these species depending on nitric acid concentration. Neptunium(IV) was not produced. (author)

  20. Radical-scavenging activities of marine-derived xyloketals and related chromanes

    Directory of Open Access Journals (Sweden)

    Zhongliang Xu

    2013-09-01

    Full Text Available Xyloketals, a new type of antioxidants from a marine mangrove fungus, have potential pharmacological properties. In this paper, the radical-scavenging activities of a series of synthetic xyloketals and related chromanes toward 2,2-diphenyl-1-picrylhydrazyl (DPPH and 2,2?-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS were evaluated by absorption spectrometry. One of the compounds (compound 10 displayed significant antioxidative action against DPPH and ABTS. A structure-activity analysis showed that the reactive sites on these compounds correlated with a hydroxy-group and also with ketal or aromatic H substituents. Based in part on a density functional theory (DFT calculation of compound 10, the antioxidant mechanism of this chromane was deduced as a possible radical-scavenging mechanism by a sequential proton loss electron-transfer (SPLET process.

  1. Effect of oxygen-derived free radicals on arachidonic acid turnover in isolated perfused rat lung

    International Nuclear Information System (INIS)

    Turnover of arachidonic acid in lung was studied by perfusing an isolated and ventilated rat lung in the presence of (14C)-arachidonic acid for 30 min. Oxygen-derived free radicals were generated within the pulmonary circulation by the action of xanthine oxidase (XO) (0.1 ?/ml) on hypoxanthine (0.1 ?mol/ml). Lung was also preperfused in the presence or absence of superoxide dismutase (SOD) (5 ?g/ml) and catalase (5 ?g/ml) prior to the addition of radiolabeled arachidonic acid and free radical generating system. After the perfusion was over, several biopsies were obtained and phospholipids were extracted and separated from one of the biopsies. Individual phospholipids were compared with known standards and counted for radioactivity. An appreciable amount of radioactivity was found in total phospholipids and in phosphatidyl choline and phosphatidyl inositol fractions in control lungs. Some radioactivity was also noticed in phosphatidyl ethanolamine fraction. The isotopic incorporation was significantly inhibited when lung was perfused in the presence of hypoxanthine and XO. The incorporation of (14C)-radioactivity was restored to the control levels when lung was preperfused with SOD and catalase. These results suggest that oxygen radicals inhibit the arachidonic acid turnover in isolated and perfused rat lung

  2. Free radicals produced by the oxidation of gallic acid: An electron paramagnetic resonance study

    Directory of Open Access Journals (Sweden)

    Wagner Brett A

    2010-08-01

    Full Text Available Abstract Background Gallic acid (3,4,5-trihydroxybenzoic acid is found in a wide variety of plants; it is extensively used in tanning, ink dyes, as well as in the manufacturing of paper. The gallate moiety is a key component of many functional phytochemicals. In this work electron paramagnetic spectroscopy (EPR was used to detect the free radicals generated by the air-oxidation of gallic acid. Results We found that gallic acid produces two different radicals as a function of pH. In the pH range between 7-10, the spectrum of the gallate free radical is a doublet of triplets (aH = 1.00 G, aH = 0.23 G, aH = 0.28 G. This is consistent with three hydrogens providing hyperfine splitting. However, in a more alkaline environment, pH >10, the hyperfine splitting pattern transforms into a 1:2:1 pattern (aH (2 = 1.07 G. Using D2O as a solvent, we demonstrate that the third hydrogen (i.e. aH = 0.28 G at lower pH is a slowly exchanging hydron, participating in hydrogen bonding with two oxygens in ortho position on the gallate ring. The pKa of this proton has been determined to be 10. Conclusions This simple and novel approach permitted the understanding of the prototropic equilibrium of the semiquinone radicals generated by gallic acid, a ubiquitous compound, allowing new insights into its oxidation and subsequent reactions.

  3. Hydroxyl radical-induced reactions in polyadenylic acid as studied by pulse radiolysis. Pt.IV. Reactions of primary radicals with reductants

    International Nuclear Information System (INIS)

    The absorption spectra of polyadenylic acid radicals in N2O saturated aqueous solutions in the absence of any scavengers and in a presence of cysteamine have been recorded after the completion of the following consecutive reactions: OH. addition, transformation of OH-adducts and intermolecular self repair between radical with open ring and amino radical being the products of later transformations. The scheme of competitive reactions with reductants (thiols) has been presented.The reactions of two OH-adducts with adenine (A) moiety of polyadenylic acid (poly A) at the positions C4 and C8 have not been observed within reductants concentrations up to 10 ?M cysteamine (CyA) and 80 ?M glutathione (GSH). From the competition studies with cationic thiols (cysteamine) as reductant and with selective scavenging of reducing radicals with oxygen two repair reactions have been observed; the first one (1.8· 108 M-1S-1) in miliseconds region of repair of the radical with open ring being the product of the transformation of A8OH adduct and the second one (4.2·106 M-1s-1) in seconds region for repair of the amino radical being the product of the transformation of A4OH adduct. However, with glutathione (anionic thiol) the protective effect was attributed only to OH. scavenging (author)

  4. Products of aqueous vitamin B5 (pantothenic acid) formed by free radical reactions

    Science.gov (United States)

    Schittl, H.; Quint, R. M.; Getoff, N.

    2007-10-01

    The radiolysis of aqueous vitamin B5 (pantothenic acid) has been investigated under various experimental conditions. The highest vitamin degradation ( G=3.22) was observed in solutions saturated with N 2O, where 90% OH radicals are operating. As final products, the following were established: aldehydes, carboxylic acids and ammonia. Their yield strongly depends on the presence/absence of air as well as on N 2O (used to convert e aq- into OH) and was determined as a function of absorbed radiation dose. HPLC-analysis showed that in all media, a main product is formed, having the highest yield in aerated solutions. Based on the chemical analysis, it appears that the OH radicals are most involved in the degradation process. A precise sequence of the reaction steps could not be given presently, because of the implication of many simultaneous reactions.

  5. Products of aqueous vitamin B5 (pantothenic acid) formed by free radical reactions

    Energy Technology Data Exchange (ETDEWEB)

    Schittl, H. [Section of Radiation Biology, Department of Nutritional Sciences, University of Vienna, Althanstr. 14, UZA II, A-1090 Vienna (Austria); Quint, R.M. [Section of Radiation Biology, Department of Nutritional Sciences, University of Vienna, Althanstr. 14, UZA II, A-1090 Vienna (Austria); Getoff, N. [Section of Radiation Biology, Department of Nutritional Sciences, University of Vienna, Althanstr. 14, UZA II, A-1090 Vienna (Austria)]. E-mail: nikola.getoff@univie.ac.at

    2007-10-15

    The radiolysis of aqueous vitamin B5 (pantothenic acid) has been investigated under various experimental conditions. The highest vitamin degradation (G=3.22) was observed in solutions saturated with N{sub 2}O, where 90% OH radicals are operating. As final products, the following were established: aldehydes, carboxylic acids and ammonia. Their yield strongly depends on the presence/absence of air as well as on N{sub 2}O (used to convert e{sub aq} {sup -} into OH) and was determined as a function of absorbed radiation dose. HPLC-analysis showed that in all media, a main product is formed, having the highest yield in aerated solutions. Based on the chemical analysis, it appears that the OH radicals are most involved in the degradation process. A precise sequence of the reaction steps could not be given presently, because of the implication of many simultaneous reactions.

  6. Products of aqueous vitamin B5 (pantothenic acid) formed by free radical reactions

    International Nuclear Information System (INIS)

    The radiolysis of aqueous vitamin B5 (pantothenic acid) has been investigated under various experimental conditions. The highest vitamin degradation (G=3.22) was observed in solutions saturated with N2O, where 90% OH radicals are operating. As final products, the following were established: aldehydes, carboxylic acids and ammonia. Their yield strongly depends on the presence/absence of air as well as on N2O (used to convert eaq- into OH) and was determined as a function of absorbed radiation dose. HPLC-analysis showed that in all media, a main product is formed, having the highest yield in aerated solutions. Based on the chemical analysis, it appears that the OH radicals are most involved in the degradation process. A precise sequence of the reaction steps could not be given presently, because of the implication of many simultaneous reactions

  7. Study of genotoxic, antigenotoxic and antioxidant activities of the digallic acid isolated from Pistacia lentiscus fruits.

    Science.gov (United States)

    Bhouri, Wissem; Derbel, Safa; Skandrani, Ines; Boubaker, Jihed; Bouhlel, Ines; Sghaier, Mohamed B; Kilani, Soumaya; Mariotte, Anne M; Dijoux-Franca, Marie G; Ghedira, Kamel; Chekir-Ghedira, Leila

    2010-03-01

    The digallic acid obtained from the fruit Pistacia lentiscus exhibits an inhibitory activity against nitrofurantoine and B[a]P induced genotoxicity when tested by the SOS chromotest bacterial assay system in the presence of Escherichia coli PQ37 strain. The antioxidant activity of the tested compound was determined by its ability to scavenge the free radical ABTS(+), to inhibit the xanthine oxidase, involved in the generation of free radicals, and to inhibit the lipid peroxidation induced by H(2)O(2) in the K562 cell line. Our results revealed that digallic acid shows an important free radical scavenging activity towards the ABTS(+) radical (99%) and protection against lipid peroxidation (68%). PMID:19563883

  8. Inhibition of free radical-induced erythrocyte hemolysis by 2-O-substituted ascorbic acid derivatives.

    Science.gov (United States)

    Takebayashi, Jun; Kaji, Hiroaki; Ichiyama, Kenji; Makino, Kazutaka; Gohda, Eiichi; Yamamoto, Itaru; Tai, Akihiro

    2007-10-15

    Inhibitory effects of 2-O-substituted ascorbic acid derivatives, ascorbic acid 2-glucoside (AA-2G), ascorbic acid 2-phosphate (AA-2P), and ascorbic acid 2-sulfate (AA-2S), on 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced oxidative hemolysis of sheep erythrocytes were studied and were compared with those of ascorbic acid (AA) and other antioxidants. The order of the inhibition efficiency was AA-2S> or =Trolox=uric acid> or =AA-2P> or =AA-2G=AA>glutathione. Although the reactivity of the AA derivatives against AAPH-derived peroxyl radical (ROO(*)) was much lower than that of AA, the derivatives exerted equal or more potent protective effects on AAPH-induced hemolysis and membrane protein oxidation. In addition, the AA derivatives were found to react per se with ROO(*), not via AA as an intermediate. These findings suggest that secondary reactions between the AA derivative radical and ROO(*) play a part in hemolysis inhibition. Delayed addition of the AA derivatives after AAPH-induced oxidation of erythrocytes had already proceeded showed weaker inhibition of hemolysis compared to that of AA. These results suggest that the AA derivatives per se act as biologically effective antioxidants under moderate oxidative stress and that AA-2G and AA-2P may be able to act under severe oxidative stress after enzymatic conversion to AA in vivo. PMID:17854711

  9. Polyphenolic Contents and Free Radical Scavenging Potential of Extracts from Leaves of Ocimum americanum L.

    OpenAIRE

    Afolayan, A. J.; O.I. Oloyede; B.T. Aluko

    2013-01-01

    This study assessed the polyphenolic contents and antioxidant activity of ethanol, butanol and ethyl acetate extracts of Ocimum americanum leaves using in vitro models. The ability of the extracts to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH?), 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS?+), hydrogen peroxide (H2O2), Nitric Oxide (NO) and hydroxyl radical (OH?) was investigated. The inhibition of lipid oxidation, reducing power, total flavonoids, phenols and flavonols con...

  10. Effect of hydrocarbon radical length of fatty acid collectors on flotation separation process of thorium ions

    International Nuclear Information System (INIS)

    It is shown experimentally that the degree of flotation separation of thorium ions collected by their means increases firstly (potassium laurate), then decreases (potassium tridecanate) and after that increases again (potassium palminate) when increasing the length of the hydrocarbon radical of potassium soaps of saturated fatty acids. The first increase of the collector efficiency is due to the decrease of solubility of thorium-containing sublates, and drop and further increase is due to the change in colloidchemical properties of sublates

  11. Effect of Acid and Base Catalyzed Hydrolysis on the Yield of Phenolics and Antioxidant Activity of Extracts from Germinated Brown Rice (GBR)

    OpenAIRE

    Shahid Iqbal; Kim Wei Chan; Ismaila Muhammad Sani; Maznah Ismail

    2012-01-01

    The influence of both acidic and basic hydrolysis on the yield, total phenolic content and antioxidative capacity of methanolic extract of germinated brown rice (GBR) was studied. Total phenolic content (TPC), total flavonoid content (TFC), 2,2?-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, 2,2?-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical cation scavenging, and ferric reducing antioxidant power (FRAP) tests were used for the measurement of antioxidant ability. Ther...

  12. Free radical mediated formation of 3-monochloropropanediol (3-MCPD) fatty acid diesters.

    Science.gov (United States)

    Zhang, Xiaowei; Gao, Boyan; Qin, Fang; Shi, Haiming; Jiang, Yuangrong; Xu, Xuebing; Yu, Liangli Lucy

    2013-03-13

    The present study was conducted to test the hypothesis that a free radical was formed and mediated the formation of 3-monochloropropanediol (3-MCPD) fatty acid diesters, a group of food contaminants, from diacylglycerols at high temperature under a low-moisture condition for the first time. The presence of free radicals in a vegetable oil kept at 120 °C for 20 min was demonstrated using an electron spin resonance (ESR) spectroscopy examination with 5,5-dimethylpyrroline-N-oxide (DMPO) as the spin trap agent. ESR investigation also showed an association between thermal treatment degree and the concentration of free radicals. A Fourier transform infrared spectroscopy (FT-IR) analysis of sn-1,2-stearoylglycerol (DSG) at 25 and 120 °C suggested the possible involvement of an ester carbonyl group in forming 3-MCPD diesters. On the basis of these results, a novel free radical mediated chemical mechanism was proposed for 3-MCPD diester formation. Furthermore, a quadrupole-time of flight (Q-TOF) MS/MS investigation was performed and detected the DMPO adducts with the cyclic acyloxonium free radical (CAFR) and its product MS ions, proving the presence of CAFR. Furthermore, the free radical mechanism was validated by the formation of 3-MCPD diesters through reacting DSG with a number of organic and inorganic chlorine sources including chlorine gas at 120 and 240 °C. The findings of this study might lead to the improvement of oil and food processing conditions to reduce the level of 3-MCPD diesters in foods and enhance food safety. PMID:23425600

  13. Uric acid a better scavenger of free radicals than vitamin C in rheumatoid arthritis

    OpenAIRE

    Mahajan, Mridula; Kaur, Sukhraj; Mahajan, Shruti; Kant, Ravi

    2009-01-01

    Uric acid an endogenous aqueous antioxidant in normal humans is present in much higher concentrations than vitamin C and has been known to cover 2/3rd of the free radical scavenging capacity in plasma. In the present study average uric acid levels of patients of rheumatoid arthritis were found to be close to the normal individuals. A unique feature was observed after classifying the patients on the basis of the duration of suffering, the patients having longer duration of disease had least ur...

  14. Conversion of a positive resist into a negative resist by induced radical reactions in solid methylmethacrylate/methacrylic acid copolymers

    International Nuclear Information System (INIS)

    A study is presented of the lifetime of radicals produced by irradiation of solid methymethacrylate/methacrylic acid copolymers with ?-rays and electron beams. Radical lifetime was investigated as a function of temperature by means of electron-spinresonance spectroscopy and radiothermoluminescence. In the presence of triallylphosphate the investigated polymers are converted into negative resist materials of high radiation sensitivity. (author)

  15. Oxygen dependency of one-electron reactions generating ascorbate radicals and hydrogen peroxide from ascorbic acid.

    Science.gov (United States)

    Boatright, William L

    2016-04-01

    The effect of oxygen on the two separate one-electron reactions involved in the oxidation of ascorbic acid was investigated. The rate of ascorbate radical (Asc(-)) formation (and stability) was strongly dependent on the presence of oxygen. A product of ascorbic acid oxidation was measurable levels of hydrogen peroxide, as high as 32.5 ?M from 100 ?M ascorbic acid. Evidence for a feedback mechanism where hydrogen peroxide generated during the oxidation of ascorbic acid accelerates further oxidation of ascorbic acid is also presented. The second one-electron oxidation reaction of ascorbic acid leading to the disappearance of Asc(-) was also strongly inhibited in samples flushed with argon. In the range of 0.05-1.2 mM ascorbic acid, maximum levels of measurable hydrogen peroxide were achieved with an initial concentration of 0.2 mM ascorbic acid. Hydrogen peroxide generation was greatly diminished at ascorbic acid levels of 0.8 mM or above. PMID:26593628

  16. The B-cell lymphoma 2 (BCL2)-inhibitors, ABT-737 and ABT-263, are substrates for P-glycoprotein

    Energy Technology Data Exchange (ETDEWEB)

    Vogler, Meike, E-mail: mv62@le.ac.uk [MRC Toxicology Unit, University of Leicester, LE1 9HN Leicester (United Kingdom); Dickens, David, E-mail: David.Dickens@liverpool.ac.uk [Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, L69 3GL Liverpool (United Kingdom); Dyer, Martin J.S., E-mail: mjsd1@le.ac.uk [MRC Toxicology Unit, University of Leicester, LE1 9HN Leicester (United Kingdom); Owen, Andrew, E-mail: aowen@liverpool.ac.uk [Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, L69 3GL Liverpool (United Kingdom); Pirmohamed, Munir, E-mail: munirp@liv.ac.uk [Department of Molecular and Clinical Pharmacology, Institute of Translational Medicine, University of Liverpool, L69 3GL Liverpool (United Kingdom); Cohen, Gerald M., E-mail: gmc2@le.ac.uk [MRC Toxicology Unit, University of Leicester, LE1 9HN Leicester (United Kingdom)

    2011-05-06

    Highlights: {yields} The BCL2-inhibitor ABT-263 is a substrate for P-glycoprotein. {yields} Apoptosis is inhibited by P-glycoprotein expression. {yields} Overexpression of P-glycoprotein may contribute to resistance to ABT-263 or ABT-737. -- Abstract: Inhibition of BCL2 proteins is one of the most promising new approaches to targeted cancer therapy resulting in the induction of apoptosis. Amongst the most specific BCL2-inhibitors identified are ABT-737 and ABT-263. However, targeted therapy is often only effective for a limited amount of time because of the occurrence of drug resistance. In this study, the interaction of BCL2-inhibitors with the drug efflux transporter P-glycoprotein was investigated. Using {sup 3}H labelled ABT-263, we found that cells with high P-glycoprotein activity accumulated less drug. In addition, cells with increased P-glycoprotein expression were more resistant to apoptosis induced by either ABT-737 or ABT-263. Addition of tariquidar or verapamil sensitized the cells to BCL2-inhibitor treatment, resulting in higher apoptosis. Our data suggest that the BCL2-inhibitors ABT-737 and ABT-263 are substrates for P-glycoprotein. Over-expression of P-glycoprotein may be, at least partly, responsible for resistance to these BCL2-inhibitors.

  17. The B-cell lymphoma 2 (BCL2)-inhibitors, ABT-737 and ABT-263, are substrates for P-glycoprotein

    International Nuclear Information System (INIS)

    Highlights: ? The BCL2-inhibitor ABT-263 is a substrate for P-glycoprotein. ? Apoptosis is inhibited by P-glycoprotein expression. ? Overexpression of P-glycoprotein may contribute to resistance to ABT-263 or ABT-737. -- Abstract: Inhibition of BCL2 proteins is one of the most promising new approaches to targeted cancer therapy resulting in the induction of apoptosis. Amongst the most specific BCL2-inhibitors identified are ABT-737 and ABT-263. However, targeted therapy is often only effective for a limited amount of time because of the occurrence of drug resistance. In this study, the interaction of BCL2-inhibitors with the drug efflux transporter P-glycoprotein was investigated. Using 3H labelled ABT-263, we found that cells with high P-glycoprotein activity accumulated less drug. In addition, cells with increased P-glycoprotein expression were more resistant to apoptosis induced by either ABT-737 or ABT-263. Addition of tariquidar or verapamil sensitized the cells to BCL2-inhibitor treatment, resulting in higher apoptosis. Our data suggest that the BCL2-inhibitors ABT-737 and ABT-263 are substrates for P-glycoprotein. Over-expression of P-glycoprotein may be, at least partly, responsible for resistance to these BCL2-inhibitors.

  18. On the reaction of lupulones, hops ?-acids, with 1-hydroxyethyl radical.

    Science.gov (United States)

    de Almeida, Natália E C; do Nascimento, Eduardo S P; Cardoso, Daniel R

    2012-10-24

    Lupulones, hops ?-acids, are one of the main constituents of the hops resin and have an important contribution to the overall bacteriostatic activity of hops during beer brewing. The use of lupulones as natural alternatives to antibiotics is increasing in the food industry and also in bioethanol production. However, lupulones are easy oxidizable and have been shown to be very reactive toward 1-hydroxyethyl radical with apparent bimolecular rate constants close to diffusion control k = 2.9 × 10(8) and 2.6 × 10(8) L mol(-1) s(-1) at 25.0 ± 0.2 °C in ethanol-water solution (10% of ethanol (v/v)) as probed by EPR and ESI-IT-MS/MS spin-trapping competitive kinetics, respectively. The free energy change for an electron-transfer mechanism is ?G° = 106 kJ/mol as calculated from the oxidation peak potential experimentally determined for lupulones (1.1 V vs NHE) by cyclic voltammetry and the reported reduction potential for 1-hydroxyethyl radical. The major reaction products identified by LC-ESI-IT-MS/MS and ultrahigh-resolution accurate mass spectrometry (orbitrap FT-MS) are hydroxylated lupulone derivatives and 1-hydroxyethyl radical adducts. The lack of pH dependence for the reaction rate constant, the calculated free energy change for electron transfer, and the main reaction products strongly suggest the prenyl side chains at the hops ?-acids as the reaction centers rather than the ?,?'-triketone moiety. PMID:23031058

  19. Performance and penetration of laccase and ABTS inks on various printing substrates.

    Science.gov (United States)

    Matilainen, Katriina; Hämäläinen, Tiina; Savolainen, Anne; Sipiläinen-Malm, Thea; Peltonen, Jouko; Erho, Tomi; Smolander, Maria

    2012-02-01

    Introduction of an enzyme and a colour-forming reagent into paper enables the development of an authenticity indicator. The purpose of this work was to study the performance of Trametes versicolor laccase, TvL, and ABTS, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) diammonium salt, in various printing substrates when printed with inkjet. The printing substrates included pre-coated mechanical paper additionally coated with PVA, silica and latex. The focus was on the bioanalytical performance and ink penetration. The setting of the printed TvL and ABTS ink was studied visually, with optical and confocal microscopy and with a so-called tape laminating technique. Technical properties of the printing substrates and effect of the surface chemistry were discussed and related to the bioanalytical properties. TvL activity persisted well during the printing. The best colour response was attained using the PVA-coated base paper. The film-forming ability of the PVA was found to be the main contributor to the colour reaction. The uniform, dense and non-porous PVA layer retains the ABTS and TVL molecules on top of the printing substrate. The high local ink concentration on the PVA coating layer combined with the absorptive paper substrate suggests that the PVA film acts as a filtering layer which retains TvL and ABTS molecules in the coating layer but allows most of the ink solvents to penetrate into the paper structure. TvL and ABTS molecules are also trapped in the PVA polymer network due to swelling effect of water. Electrostatic attractions between the PVA and ABTS and TvL molecules do not contribute to the colour reaction. PMID:22051108

  20. Study of role of methyl radicals in ?-radiolysis of crystalline acetic acid at 770K

    International Nuclear Information System (INIS)

    The isotopic composition of the methane and the yield of methyl radicals formed by the radiolysis of the polycrystalline mixtures CH3COOH + CD3COOD and CH3COOD + CD3COOD + CD3COOD with ? rays at 770K was investigated. It was concluded that methane is formed from the methyl group of one acetic acid molecule and a hydrogen atom fromt he methyl group of another molecule. The formation of half the methane evolved can be explained by reactions of the type: CH3COOH+?CH3+CO2+H+; CH3+CO2+CH3COOH?CH4+CH2COOH. The other half of the methane arises from anion-radical reactions as the samples are warmed to room temperature

  1. Rates and mechanism of the reactions of hydroxyl radicals with acetic, deuterated acetic, and propionic acids in the gas phase

    International Nuclear Information System (INIS)

    Rate constants for the reactions of hydroxyl radicals with the monomer and dimer of acetic acid, deuterated acetic acids, and propionic acid have been determined by a laser photolysis-resonance absorption technique. Hydroxyl radicals were generated by photolysis of the acids at 222 nm with a KrCl laser and their decay was followed by time-resolved resonance absorption. The monomers of acetic and deuterated acetic acids reacted with OH much faster than the dimers, whereas the monomer and dimer of propionic acid reacted with about equal rate constants. A primary isotope effect was observed when carboxylic but not alkyl hydrogen was substituted by deuterium in acetic acid. The results are entirely consistent with the two-channel mechanism that we proposed for the reaction of OH with formic acid. The results are interpreted in terms of the variations in C-H bond strengths and in equilibrium constants for adduct formation of the acids studied

  2. Antioxidant and Free Radical Scavenging Capacity of Seed and Shell Essential Oils Extracted from Abrus precatorius (L

    Directory of Open Access Journals (Sweden)

    Sunday O. Okoh

    2014-04-01

    Full Text Available Essential oils from plants have been proven safe as natural antioxidants, and few are already marketed as digestive enhancers as well as in prevention of several degenerative diseases. This study evaluated the antioxidant capacity of seed and shell essential oils of Abrus precatorius (L, a herb used for ethno-medicinal practices in Nigeria. The essential oils were obtained by hydro-distillation. The ability of the oils to act as hydrogen/electrons donor or scavenger of radicals were determined by in-vitro antioxidant assays using 2,2-diphenyl-2-picryl-hydrazyl free radical (DPPH. scavenging; 2,2?-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS radical scavenging; lipid peroxide and nitric oxide radicals scavenging assays. The IC50 of the seed and shell oils (2.10 mg/mL and 1.20 mg/mL respectively showed that antioxidant activity is higher than that for the standard drugs (3.20 mg/mL and 3.40 mg/mL for the nitric oxide scavenging assay. The lipid peroxidation radical activity of the oils were similar to vitamin C, weak DPPH and ABTS radical scavenging activities were discovered in comparison to vitamin C and rutin. Generally, in the four antioxidant assays, a significant correlation existed between concentrations of the oils and percentage inhibition of free radicals and lipid peroxidation. The composition of A. precatorius essential oils reported earlier may account for their antioxidant capacity.

  3. Breaking the dogma: PCB-derived semiquinone free radicals do not form covalent adducts with DNA, GSH, and amino acids.

    Science.gov (United States)

    Wangpradit, Orarat; Rahaman, Asif; Mariappan, S V Santhana; Buettner, Garry R; Robertson, Larry W; Luthe, Gregor

    2016-02-01

    Covalent bond formations of free radical metabolites with biomolecules like DNA and proteins are thought to constitute a major mechanism of toxicity and carcinogenesis. Glutathione (GSH) is generally accepted as a radical scavenger protecting the cell. In the present study, we investigated a semiquinone radical (SQ(?-)) metabolite of the semivolatile 4-chlorobiphenyl, using electron paramagnetic resonance spectroscopy, and oxygen consumption. Proton nuclear magnetic resonance ((1)H NMR) and liquid chromatography-mass spectrometry (LC-MS) were also employed to elucidate the radical interaction with DNA, amino acids, and GSH. We found that DNA and oligonucleotides stabilized SQ(?-) by electron delocalization in the ?-stacking system, resulting in persistent radical intercalated, rather than forming a covalent bond with SQ(?-). This finding was strongly supported by the semiempirical calculation of the semioccupied molecular orbital and the linear combination of the atomic orbitals, indicating 9.8 kcal mol(-1) energy gain. The insertion of SQ(?-) into the DNA strand may result in DNA strand breaks and interruption of DNA replication process or even activate radical mediated secondary reactions. The presence of amino acids resulted in a decrease of the electron paramagnetic resonance (EPR) signal of SQ(?-) and correlated with their isoelectric points. The pH shifts the equilibrium of the dianions of hydroquinone and influenced indirectly the formation of SQ(?-). Similar findings were observed with GSH and Cys. GSH and Cys functioned as indirect radical scavengers; their activities depend on their chemical equilibria with the corresponding quinones, and their further reaction via Michael addition. The generally accepted role of GSH as radical scavenger in biological systems should be reconsidered based upon these findings, questioning the generally accepted view of radical interaction of semiquinones with biologically active compounds, like DNA, amino acids, proteins, and radical scavengers like GSH. PMID:26396011

  4. Reactivity of chlorine radical with submicron palmitic acid particles: kinetic measurements and products identification

    Directory of Open Access Journals (Sweden)

    M. Mendez

    2013-06-01

    Full Text Available The heterogeneous reaction of Cl. radicals with sub-micron palmitic acid (PA particles was studied in an aerosol flow tube in the presence or in the absence of O2. Fine particles were generated by homogeneous condensation of PA vapors and introduced in the reactor where chlorine atoms are produced by photolysis of Cl2 using UV lamps surrounding the reactor. The effective reactive uptake coefficient (γ has been determined from the rate loss of PA measured by GC/MS analysis of reacted particles as a function of the chlorine exposure. In the absence of O2, γ = 14 ± 5 indicates efficient secondary chemistry involving Cl2. GC/MS analyses have shown the formation of monochlorinated and polychlorinated compounds in the oxidized particles. Although, the PA particles are solid, the complete mass can be consumed. In the presence of oxygen, the reaction is still dominated by secondary chemistry but the propagation chain length is smaller than in the absence of O2 which leads to an uptake coefficient γ = 3 ± 1. In the particulate phase, oxocarboxylic acids and dicarboxylic acids are identified by GC/MS. Formation of alcohols and monocarboxylic acids are also suspected. All these results show that solid organic particles could be efficiently oxidized by gas-phase radicals not only on their surface, but also in bulk by mechanisms which are still unclear. Furthermore the identified reaction products are explained by a chemical mechanism showing the pathway of the formation of more functionalized products. They help to understand the aging of primary tropospheric aerosol containing fatty acids.

  5. Electrospray ionization mass spectrometry applied to study the radical acetylation of amino acids, peptides and proteins

    Scientific Electronic Library Online (English)

    Atecla N. L., Alves; Leticia D. L., Jedlicka; Júlio, Massari; Maria A., Juliano; Etelvino J. H., Bechara; Nilson A., Assunção.

    2013-12-01

    Full Text Available Recentemente nosso grupo demostrou experimentalmente que a hipótese de produção de radical acetil em meio tamponado no sistema diacetil/peroxinitrito era possível. Diacetil é um flavorizante em alimentos, cigarros e bebidas. O peroxinitrito é encontrado na mitocôndria, e em certas condições como um [...] processo de infeção em humanos, a concentração aumenta significativamente. Em sistemas biológicos, radicais podem facilmente modificar a estrutura e atividade de ácidos nucleicos, proteínas e outras biomoléculas, causando significativo estres oxidativo. Baseado em dados de ressonância magnética e espectrometria de massas, este artigo apresenta os produtos que provam a produção do radical acetil e a formação de compostos estáveis devido à ligação covalente entre o acetil e os aminoácidos (produtos acetilados), e os adutos de peptídeos e proteínas. Estes materiais foram separados por eletroforese capilar e identificados por espectrometria de massas. O meio reacional consistiu da mistura de diacetil e peroxynitrito em uma relação de 1:2 e em 20 mmol L-1 de fosfato de sódio, no valor de pH 7,2. Estes experimentos também revelam a dupla acetilação da lisina, demonstrando a alta reatividade do composto com biomoléculas contendo grupos de nitrogênio, abundantemente encontradas em sistemas biológicos. A mudança estrutural de uma molécula acetilada é uma fonte de modificações pós-tradução com inúmeras consequências biológicas. Abstract in english Recently, our group proposed a process that generated acetyl radicals in a reaction medium buffered with a diacetyl/peroxynitrite system. Diacetyl is a flavoring agent in food, cigarettes and drinks. Peroxynitrite is found in mitochondria, and in certain conditions, such as an infection in humans, i [...] ts concentration is augmented significantly. In biological systems, radical compounds can easily modify the structure and activity of nucleic acids, proteins and other biomolecules, causing significant oxidative stress. Based on paramagnetic resonance and mass spectrometry data, this work discusses products that prove acetyl radicals are produced and are able to form stable covalent bonds with amino acid (acetylated products), peptide and protein adducts. These materials were separated and detected by capillary electrophoresis coupled with tandem mass spectrometry or offline mass spectrometry. The reaction medium contained a 1:2 mixture of diacetyl and peroxynitrite dissolved in 200 mmol L-1 of pH 7.2 sodium phosphate buffer. These experiments also reveal the double acetylation of lysine, demonstrating the high reactivity of these compounds when in contact with nitrogen-containing biomolecules readily found in biological systems. These structural changes might be an epigenetic source of post-translational protein modification.

  6. Comparative evaluation of free radical scavenging activity of Boerhaavia diffusa root extracts (BDRE) and determination of dose effectivity against radiation induced damages in Swiss albino mice

    OpenAIRE

    Sharma, J.; Saini, M. R.; P Dhakar

    2012-01-01

    Summary: Purpose of the study was to evaluate free radical scavenging activity (FRSA) of root extracts of Boerhaavia diffusa in different solvents and to examine its dose effectivity against radiation induced damages in Swiss albino mice. Scavenging activities of aqueous, ethanolic and hydroethanolic extracts of B. diffusa roots were evaluated by DPPH (2, 2-diphenyl-1 picryl hydrazyl), ABTS (2,2’-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid) and NO (nitric oxide) assay to find the most e...

  7. Mechanism of benzophenone ketyl radical formation in acid alcohols studied by pulse-radiolysis and rigid-matrix techniques

    International Nuclear Information System (INIS)

    The mechanism of the benzophenone ketyl radical formation in acid methanol, ethanol, and 2-propanol was studied by using pulse-radiolysis and rigid-matrix techniques. When a 0.1 M ethanol solution of benzophenone containing hydrogen chloride (1.2 M) was irradiated at 77 K by ? rays from 60Co, the absorption spectrum of the trapped intermediates was ascribed solely to benzophenone ketyl radicals. The pulse-radiolysis study of the solution at 100 K revealed that the ketyl radicals are produced by protonation of presolvated benzophenone anion radicals. At 153 K, the ketyl radicals were observed to be produced also by hydrogen-atom transfer from CH3CHOH and CH3CH(OH)CH3 to benzophenone; the temperature dependence of the transfer rate constant was studied

  8. Isolation and Characterisation of in Vitro and Cellular Free Radical Scavenging Peptides from Corn Peptide Fractions

    Directory of Open Access Journals (Sweden)

    Liying Wang

    2015-02-01

    Full Text Available Corn gluten meal, a corn processing industry by-product, is a good source for the preparation of bioactive peptides due to its special amino acid composition. In the present study, the in vitro and cellular free radical scavenging activities of corn peptide fractions (CPFs were investigated. Results indicated that CPF1 (molecular weight less than 1 kDa and CPF2 (molecular weight between 1 and 3 kDa exhibited good hydroxyl radical, superoxide anion radical and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonicacid diammonium salt (ABTS radical scavenging activity and oxygen radical absorbance capacity (ORAC. Meanwhile, the in vitro radical scavenging activity of CPF1 was slightly higher than that of CPF2. Both CPF1 and CPF2 also exhibited significant cytoprotective effects and intracellular reactive oxygen species scavenging activity in Caco-2 cells exposed to hydrogen peroxide (H2O2. The amino acid composition analysis revealed that the CPF were rich in hydrophobic amino acids, which comprised of more than 45% of total amino acids. An antioxidant peptide sequence of Tyr-Phe-Cys-Leu-Thr (YFCLT was identified from CPF1 using matrix-assisted laser desorption/ionization time-of-flight/time-of-?ight mass spectrometry (MALDI TOF/TOF MS. The YFCLT exhibited excellent ABTS radical scavenging activity with a 50% effective concentration (EC50 value of 37.63 µM, which was much lower than that of Trolox. In conclusion, corn gluten meal might be a good source to prepare antioxidant peptides.

  9. Water soluble and heat resistant polymers by free radical polymerization of lactic acid-based monomers

    Science.gov (United States)

    Tanaka, Hitoshi; Kibayashi, Tatsuya; Niwa, Miki

    2013-08-01

    Tactic heat resistant polymer was prepared by free radical polymerization of lactic acid-based monomers, i.e. chiral 2-isopropyl-5-methylene-1,3-dioxolan-4-ones (1). The polymerization of 1 proceeded smoothly without ring-opening to give a polymer with high isotacticity (mm) of 29.7~100% and glass transition temperature (Tg) of 172~213°C. 1 also showed high reactivity in the copolymerization with styrene and methyl methacrylate, and the incorporation of 1 unit in the copolymer structure increased Tg of each polymer. In addition, hydrolysis of poly(1) produced a new type of water soluble poly(lactic acid), i.e. poly(?-hydroxy acrylate), and poly(?-hydroxy acrylate-co-divinyl benzene) hydrogel absorbed water as high as 1000 times of the original polymer weight.

  10. Electron spin resonance studies of barriers to hindered rotation in acetic acid, acetamide, and peptide radicals

    International Nuclear Information System (INIS)

    Activation energies for methyl group rotation in the radicals of type H3C-C2O) as well as in 8 M NaOD glasses have produced the acetic acid anion, the acetate dianion, and the acetamide anion. ESR spectra of these have revealed a doublet (ca. 32G) at 90 K reversibly interconverting to a 1:3:3:1 quartet, of ca. 15-G hyperfine splitting, at higher temperatures (170 K). This interconversion has been attributed to the hindered internal rotation of the methyl group about the H3C-C< bond. The ESR spectra are analyzed using modified Bloch equations for the three-jump process. The mean lifetime (tau) at each temperature (T) has been estimated by a comparison of experimental and simulated ESR spectra. The activation energy (E/sub a/) for the sixfold barrier to the rotation is found to be 5.0 +- 0.5 kcal/mol in the acetate dianion and is about 3.0 kcal/mol for the acetate and acetamide as well as N-acetylamino acids. ESR spectra characteristic of the tunneling methyl group were observed at low temperature (20 K< T<100K) for the radicals produced in ?-irradiated polycrystalline samples of glycyl-L-alanine and L-alanyl-L-alanine. 3 figures, 1 table

  11. Lipoxygenase-mediated pro-radical effect of melatonin via stimulation of arachidonic acid metabolism

    International Nuclear Information System (INIS)

    We have shown that melatonin immediately and transiently stimulates intracellular free radical production on a set of leukocytes, possibly as a consequence of calmodulin binding. We show here that melatonin-induced ROS are produced by lipoxygenase (LOX), since they are prevented by a set of LOX inhibitors, and are accompanied by increase of the 5-LOX product 5-HETE. LOX activation is accompanied by strong liberation of AA; inhibition of Ca2+-independent, but not Ca2+-dependent, phospholipase A2 (PLA2), prevents both melatonin-induced arachidonic acid and ROS production, whereas LOX inhibition only prevents ROS, indicating that PLA2 is upstream with respect to LOX, as occurs in many signaling pathways. Chlorpromazine, an inhibitor of melatonin-calmodulin interaction, inhibits both ROS and arachidonic acid production, thus possibly placing calmodulin at the origin of a melatonin-induced pro-radical pathway. Interestingly, it is known that Ca2+-independent PLA2 binds to calmodulin: our results are compatible with PLA2 being liberated by melatonin from a steady-state calmodulin sequestration, thus initiating an arachidonate signal transduction. These results delineate a novel molecular pathway through which melatonin may participate to the inflammatory response.

  12. Degradation of hyaluronic acid, poly- and monosaccharides, and model compounds by hypochlorite : evidence for radical intermediates and fragmentation

    DEFF Research Database (Denmark)

    Hawkins, C L; Davies, Michael Jonathan

    1998-01-01

    Degradation of hyaluronic acid by oxidants such as HO. and HOCl/CIO- is believed to be important in the progression of rheumatoid arthritis. While reaction of hyaluronic acid with HO. has been investigated extensively, reaction with HOCl/ClO- is less well defined. Thus, little is known about the site(s) of HOCl/ClO- attack, the intermediates formed, or the mechanism(s) of polymer degradation. In this study reaction of HOCl/ClO- with amides, sugars, polysaccharides, and hyaluronic acid has been monitored by UV-visible (220-340 nm) and EPR spectroscopy. UV-visible experiments have shown that HOCl/ClO- reacts preferentially with N-acetyl groups. This reaction is believed to give rise to transient chloramide (R-NCl-C(O)-R') species, which decompose rapidly to give radicals via either homolysis (to produce N. and Cl.) or heterolysis (one-electron reduction, to give N. and Cl.) of the N--C bond. The nature of the radicals formed has been investigated by EPR spin trapping. Reaction of HOCl/ClO- with hyaluronic acid, chondroitin sulphates A and C, N-acetyl sugars, and amides gave novel, carbon-centered, spin adducts, the formation of which is consistent with selective initial attack at the N-acetyl group. Thus, reaction with hyaluronic acid and chondroitin sulphate A, appears to be localized at the N-acetylglucosamine sugar rings. These carbon-centered radicals are suggested to arise from rapid rearrangement of initial nitrogen-centered radicals, formed from the N-acetyl chloramide, by reactions analogous to those observed with alkoxyl radicals. The detection of increasing yields of low-molecular-weight radical adducts from hyaluronic acid and chondroitin sulphate A with increasing HOCl/ClO-concentrations suggests that formation of the initial nitrogen-centered species on the N-acetylglucosamine rings, and the carbon-centered radicals derived from them, brings about polymer fragmentation.

  13. Electron Paramagnetic Resonance Examination of Free Radical Formation in Salicylic Acid and Urea Exposed to UV Irradiation

    OpenAIRE

    Ramos, Pawe?; Pilawa, Barbara

    2016-01-01

    Free radicals formed by UV irradiation of the two magistral formulas applied on the skin, salicylic acid and urea, were examined by X-band (9.3?GHz) EPR spectroscopy. The influence of the time of UVA (315–400?nm) irradiation on free radical properties and concentrations in the drug samples was determined. The nonirradiated magistral formula did not contain free radicals. Amplitudes (A) and linewidths (?Bpp) of EPR spectra were analysed. Fast spin-lattice relaxation process existed in the test...

  14. Characterization of fatty acids, bioactive lipids, and radical scavenging activity of Canterbury bells seed oil

    Directory of Open Access Journals (Sweden)

    Hassanien, M. F.R.

    2014-06-01

    Full Text Available The aim of this study was to characterize the chemical composition and radical scavenging activity of Canterbury bells (Campanula medium seed oil. C. medium seeds contained 9.2% extractable oil. The lipid classes, fatty acids, phytosterol and tocopherol composition of C. medium seed oil were determined. The amount of neutral lipids in the oil was the highest, followed by glycolipids and phospholipids. Linoleic and oleic were the main fatty acids. C. medium oil is characterized by high levels of phytosterols and β-sitosterol was the main compound. β-Tocopherol constituted 42.5% of the total tocopherol content followed by γ-tocopherol. The radical scavenging activity (RSA toward 1,1-diphenyl-2-picrylhydrazyl (DPPH radicals and galvinoxyl radicals of C. medium oil were higher than those of extra virgin olive oil. The diverse potential uses of C. medium oil may make this plant industrially important.El objetivo de este estudio fue caracterizar la composición química y la actividad de captación de radicales de aceites de semillas de campanillas de Canterbury (Campanula medium. Las semillas de C. medium contenían 9,2 % de aceite extraíble. Se determinó la composición de las diferentes clases de lípidos, ácidos grasos, fitoesteroles y tocoferoles. La cantidad de lípidos neutros en el aceite fue mayoritario, seguido de glicolípidos y fosfolípidos. Linoleico y oleico fueron los ácidos grasos principales. El aceite de C. medium se caracteriza por altos niveles de fitoesteroles y β-sitosterol fue el compuesto principal. β-tocoferol constituía 42,5 % del contenido total de tocoferol seguido de γ-tocoferol. La actividad de captación de radicales (RSA a 1,1-difenil-2- picrilhidrazil (DPPH y radicales galvinoxil de C. medium fueron superiores a las de aceite de oliva virgen extra. Los diversos usos potenciales de los aceites de C. medium pueden hacer que esta planta pueda ser importante industrialmente.

  15. Radical scavenging activity and composition of raspberry (Rubus idaeus) leaves from different locations in Lithuania.

    Science.gov (United States)

    Venskutonis, P R; Dvaranauskaite, A; Labokas, J

    2007-02-01

    Raspberry (Rubus idaeus) leaves, collected in different locations of Lithuania were extracted with ethanol and the extracts were tested for their antioxidant activity (AA) by using ABTS(.)(+) decolourisation and DPPH(.) scavenging methods. All extracts were active, with radical scavenging capacity at the used concentrations from 20.5 to 82.5% in DPPH(.) reaction system and from 8.0 to 42.7% in ABTS(.)(+) reaction. The total amount of phenolic compounds in the leaves varied from 4.8 to 12.0 mg of gallic acid equivalents (GAE) in 1 g of plant extract. Quercetin glucuronide, quercetin-3-O-glucoside and rutin were identified in the extracts. PMID:17215088

  16. Free radical scavenging activity of ethanolic extracts from herbs and spices commercialized in Brazil

    Directory of Open Access Journals (Sweden)

    Lilian Regina Barros Mariutti

    2008-12-01

    Full Text Available Ethanolic extracts from 23 different dried herbs and spices commercialized in Brazil were investigated for their free radical scavenging properties using the stable free radicals 2,2'-diphenyl-?-picrylhydrazyl (DPPH• and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS•+, and Trolox as reference (TEAC for both radicals. The kinetic curves for both radicals showed to follow the first order kinetics model and the decay rate constant (k obs was calculated. For all the samples, the two methods showed a good linear TEAC correlation, indicating that the average reactivity of the compounds present in the ethanolic extracts was similar. Sage and rosemary extracts showed the highest free radical scavenging capacities, while onion showed negligible activity and colorifico, one of the most consumed spices in Brazil, showed low ABTS•+ scavenging activity. Three distinct situations were found for the extracts concerning the DPPH• scavenging capacities: (1 extracts, like rosemary and laurel, that presented the same efficient concentrations (EC50 but differed in the TEAC values and velocities of action (k obs, (2 extracts, such as garlic and basil, that showed similar EC50 and TEAC values, but different k obs values and (3 extracts that reacted at the same velocities but completely differed in the free radical scavenging capacities, like black pepper, savory, nutmeg, rosemary and sage. Similar considerations could be done for the ABTS•+ results. For the first time the ABTS•+ scavenging activity for allspice, basil, cardamom, chives, colorifico, cumin, dill, laurel, marjoram, parsley and tarragon was reported.Extratos etanólicos de 23 ervas e condimentos desidratados comercializados no Brasil foram analisados quanto as suas propriedades antioxidantes utilizando os radicais 2,2'-difenil-?-picrilhidrazil (DPPH• e ácido 2,2'-azino-bis(3-etilbenzotiazolina-6-sulfônico (ABTS•+, Trolox foi usado como referência para ambos radicais. As curvas cinéticas seguiram o modelo cinético de primeira ordem, e a partir destas foram calculadas as constantes de velocidade de (k obs. Os extratos de sálvia e de alecrim apresentaram as maiores capacidades redutoras de radicais livres, enquanto o extrato de cebola praticamente não apresentou atividade e o colorífico, um dos condimentos mais consumidos no Brasil, apresentou baixa atividade de aprisionamento de radicaisABTS•+. Três situações distintas foram observadas em relação à capacidade de aprisionar radicais DPPH•: (1 extratos, como os de alecrim e de louro, que apresentaram as mesmas concentrações eficientes (EC50, porém, valores de TEAC e velocidade de ação (k obs distintos ; (2 extratos, como os de alho e de manjericão, que apresentaram valores similares de EC50 e TEAC, com valores distintos de k obs e (3 extratos com a mesma velocidade de ação que diferiram totalmente na capacidade de aprisionamento de radicais livres, como de pimenta preta, segurelha, noz moscada, alecrim e sálvia. Considerações semelhantes podem ser feitas para os resultados de ABTS•+. Osdois métodos apresentaram boa correlação de TEAC, indicando que a reatividade dos compostos presentes nos extratos etanólicos foi similar. A atividade redutora de ABTS•+ para pimenta da Jamaica, manjericão, cardamomo, cebolinha, colorífico, cominho, dill, louro, manjerona, salsinha e estragão foi reportada pela primeira vez.

  17. Free radical scavenging activity of ethanolic extracts from herbs and spices commercialized in Brazil

    Scientific Electronic Library Online (English)

    Lilian Regina Barros, Mariutti; Gisela Pizarro de Mattos, Barreto; Neura, Bragagnolo; Adriana Zerlotti, Mercadante.

    2008-12-01

    Full Text Available Extratos etanólicos de 23 ervas e condimentos desidratados comercializados no Brasil foram analisados quanto as suas propriedades antioxidantes utilizando os radicais 2,2'-difenil-?-picrilhidrazil (DPPH•) e ácido 2,2'-azino-bis(3-etilbenzotiazolina-6-sulfônico) (ABTS•+), Trolox foi usado como referê [...] ncia para ambos radicais. As curvas cinéticas seguiram o modelo cinético de primeira ordem, e a partir destas foram calculadas as constantes de velocidade de (k obs). Os extratos de sálvia e de alecrim apresentaram as maiores capacidades redutoras de radicais livres, enquanto o extrato de cebola praticamente não apresentou atividade e o colorífico, um dos condimentos mais consumidos no Brasil, apresentou baixa atividade de aprisionamento de radicaisABTS•+. Três situações distintas foram observadas em relação à capacidade de aprisionar radicais DPPH•: (1) extratos, como os de alecrim e de louro, que apresentaram as mesmas concentrações eficientes (EC50), porém, valores de TEAC e velocidade de ação (k obs) distintos ; (2) extratos, como os de alho e de manjericão, que apresentaram valores similares de EC50 e TEAC, com valores distintos de k obs e (3) extratos com a mesma velocidade de ação que diferiram totalmente na capacidade de aprisionamento de radicais livres, como de pimenta preta, segurelha, noz moscada, alecrim e sálvia. Considerações semelhantes podem ser feitas para os resultados de ABTS•+. Osdois métodos apresentaram boa correlação de TEAC, indicando que a reatividade dos compostos presentes nos extratos etanólicos foi similar. A atividade redutora de ABTS•+ para pimenta da Jamaica, manjericão, cardamomo, cebolinha, colorífico, cominho, dill, louro, manjerona, salsinha e estragão foi reportada pela primeira vez. Abstract in english Ethanolic extracts from 23 different dried herbs and spices commercialized in Brazil were investigated for their free radical scavenging properties using the stable free radicals 2,2'-diphenyl-?-picrylhydrazyl (DPPH•) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS•+), and Trolox a [...] s reference (TEAC) for both radicals. The kinetic curves for both radicals showed to follow the first order kinetics model and the decay rate constant (k obs) was calculated. For all the samples, the two methods showed a good linear TEAC correlation, indicating that the average reactivity of the compounds present in the ethanolic extracts was similar. Sage and rosemary extracts showed the highest free radical scavenging capacities, while onion showed negligible activity and colorifico, one of the most consumed spices in Brazil, showed low ABTS•+ scavenging activity. Three distinct situations were found for the extracts concerning the DPPH• scavenging capacities: (1) extracts, like rosemary and laurel, that presented the same efficient concentrations (EC50 ) but differed in the TEAC values and velocities of action (k obs), (2) extracts, such as garlic and basil, that showed similar EC50 and TEAC values, but different k obs values and (3) extracts that reacted at the same velocities but completely differed in the free radical scavenging capacities, like black pepper, savory, nutmeg, rosemary and sage. Similar considerations could be done for the ABTS•+ results. For the first time the ABTS•+ scavenging activity for allspice, basil, cardamom, chives, colorifico, cumin, dill, laurel, marjoram, parsley and tarragon was reported.

  18. Concerted effects in the reaction of ·OH radicals with aromatics: radiolytic oxidation of salicylic acid

    International Nuclear Information System (INIS)

    Liquid chromatographic and capillary electrophoretic studies have been used to resolve the products produced in the radiolytic oxidation of salicylic acid in aqueous solution. These studies have shown that, as in the case of phenol, ·OH radicals preferentially add to the positions ortho and para to the OH substituent. However, in contrast to its reaction with phenol, addition at the ortho position is favored over addition at the para position. Because ·OH radical is a strong electrophile this difference suggests that the electron population at the ortho position in the salicylate anion is enhanced as a result of the hydrogen bonding in salicylic acid

  19. ABT-773: Pharmacokinetics and Interactions with Ranitidine and Sucralfate

    OpenAIRE

    Pletz, M. W.; Preechachatchaval, V.; Bulitta, J.; Allewelt, M.; Burkhardt, O.; Lode, H

    2003-01-01

    We assessed the pharmacokinetics and interaction of ABT-773 in 12 volunteers receiving ABT-773 alone or concomitantly with ranitidine or sucralfate. Data for 150 mg of ABT-773 were as follows: the maximum concentration of the drug in plasma (Cmax) was 318 ng/ml, its half-life was 5.66 h, and its area under the plasma concentration-time curve from 0 h to ? (AUC0-?) was 1,662 ng?·?h/ml. Coadministration of ranitidine, reduced the Cmax (?25.7%) and AUC0-? (?15.8%) significantly. Sucralfate had n...

  20. ABT-089, but not ABT-107, ameliorates nicotine withdrawal-induced cognitive deficits in C57BL6/J mice.

    Science.gov (United States)

    Yildirim, Emre; Connor, David A; Gould, Thomas J

    2015-04-01

    Nicotine withdrawal produces cognitive deficits that can predict relapse. Amelioration of these cognitive deficits emerges as a target in current smoking cessation therapies. In rodents, withdrawal from chronic nicotine disrupts contextual fear conditioning (CFC), whereas acute nicotine enhances this hippocampus-specific learning and memory. These modifications are mediated by ?2-subunit-containing (?2*) nicotinic acetylcholine receptors in the hippocampus. We aimed to test ABT-089, a partial agonist of ?4?2*, and ABT-107, an ?7 nicotinic acetylcholine receptor agonist, for amelioration of cognitive deficits induced by withdrawal from chronic nicotine in mice. Mice underwent chronic nicotine administration (12.6?mg/kg/day or saline for 12 days), followed by 24?h of withdrawal. At the end of withdrawal, mice received 0.3 or 0.6?mg/kg ABT-089 or 0.3?mg/kg ABT-107 (doses were determined through initial dose-response experiments and prior studies) and were trained and tested for CFC. Nicotine withdrawal produced deficits in CFC that were reversed by acute ABT-089, but not ABT-107. Cued conditioning was not affected. Taken together, our results suggest that modulation of hippocampal learning and memory using ABT-089 may be an effective component of novel therapeutic strategies for nicotine addiction. PMID:25426579

  1. Free radical reaction pathway, thermohemistry of peracetic acid homolysis and its application for phenol degradation: spectroscopic sti=udy and quantum chemistry calculations

    OpenAIRE

    Rokhina, E.V.; Makarova, K.; Golovina, E.A.; Van As, H.; Virkutyte, J.

    2010-01-01

    The homolysis of peracetic acid (PAA) as a relevant source of free radicals (e.g., •OH) was studied in detail. Radicals formed as a result of chain radical reactions were detected with electron spin resonance and nuclear magnetic resonance spin trapping techniques and subsequently identified by means of the simulation-based fitting approach. The reaction mechanism, where a hydroxyl radical was a primary product of O?O bond rupture of PAA, was established with a complete assessment of relevant...

  2. New easy method for obtaining approximate redox potentials of radicals, produced by 60Co-?-radiolysis, using heteropoly electrolytes of molybdenum and tungsten as electron acceptors. The redox potential of some alcohol and organic acid radicals

    International Nuclear Information System (INIS)

    The reducing ability of short lived radicals can be studied by reacting them with electron acceptors whose redox potential is known. Heteropoly electrolytes of molybdenum and tungsten are used for this purpose. The reduction of these species proceeds in distinct reduction steps producing the corresponding heteropoly blues until the potential of the next reduction step is more negative than the potential of the radical. The apparent redox potentials of some alcohols and formic acid radicals have been determined. (U.S.)

  3. Caffeic Acid Inhibits the Formation of 7-Carboxyheptyl Radicals from Oleic Acid under Flavin Mononucleotide Photosensitization by Scavenging Singlet Oxygen and Quenching the Excited State of Flavin Mononucleotide

    Directory of Open Access Journals (Sweden)

    Marie Asano

    2014-08-01

    Full Text Available We examined the effects of caffeic acid (CA and related compounds on 7-carboxyheptyl radical formation. This analysis was performed using a standard D2O reaction mixture containing 4.3 mM oleic acid, 25 ?M flavin mononucleotide (FMN, 160 mM phosphate buffer (pH 7.4, 10 mM cholic acid, 100 mM ?-(4-pyridyl-1-oxide-N-tert-butylnitrone, and 1 mM Fe(SO42(NH42 during irradiation with 7.8 J/cm2 at 436 nm. 7-Carboxyheptyl radical formation was inhibited by CA, catechol, gallic acid, chlorogenic acid, ferulic acid, noradrenalin, 2-hydroxybenzoic acid, 3-hydroxybenzoic acid, and 4-hydroxybenzoic acid. Quinic acid, benzoic acid, and p-anisic acid had no effect on radical formation. These results suggest that a phenol moiety is essential for these inhibitory effects. The fluorescence intensity of FMN decreased by 69% ± 2% after CA addition, suggesting that CA quenches the singlet excited state of FMN. When 1 mM CA was added to a standard reaction mixture containing 25 ?M FMN, 140 mM phosphate buffer (pH 7.4, and 10 mM 4-oxo-2,2,6,6-tetramethylpiperidine, the electron spin resonance signal of 4-oxo-2,2,6,6-tetramethylpiperidinooxy disappeared. This finding suggests that singlet oxygen was scavenged completely by CA. Therefore, CA appears to inhibit 7-carboxyheptyl radical formation by scavenging singlet oxygen and quenching the excited state of FMN.

  4. Administration of the nicotinic acetylcholine receptor agonists ABT-089 and ABT-107 attenuates the reinstatement of nicotine-seeking behavior in rats.

    Science.gov (United States)

    Lee, Alycia M; Arreola, Adrian C; Kimmey, Blake A; Schmidt, Heath D

    2014-11-01

    Current smoking cessation pharmacotherapies have modest efficacy, and most smokers relapse within the first few days after a quit attempt. Nicotine withdrawal-induced craving and cognitive impairments predict smoking relapse during abstinence and suggest that cognitive-enhancing drugs may prevent relapse. ABT-089 and ABT-107 are subtype-selective nAChR agonists that improve cognitive performance in laboratory animals. However, there are no studies examining the effects of ABT-089 and ABT-107 on nicotine self-administration and the reinstatement of nicotine-seeking behavior, an animal model of relapse in human smokers. The goal of the present study was to determine the effects of the ?4?2*/?6?2* nAChR agonist ABT-089 and the ?7 nAChR agonist ABT-107 on nicotine taking and seeking in rats. The effects of acute ABT-089 and ABT-107 pretreatment on nicotine self-administration and reinstatement were tested in male Sprague Dawley rats. Parallel studies of ABT-089 and ABT-107 on sucrose self-administration and reinstatement were tested in separate groups of rats to determine if the effects of these drug treatments generalized to other reinforced behaviors. Nicotine and sucrose self-administration behaviors were not altered following acute administration of ABT-089 (0, 0.12, 1.2 and 12.0mg/kg) or ABT-107 (0, 0.03 and 0.3mg/kg). In contrast, both ABT-089 and ABT-107 pretreatment dose-dependently attenuated nicotine reinstatement. These effects were reinforcer-specific as no effects of ABT-089 or ABT-107 pretreatment on sucrose seeking were noted. Taken together, these findings suggest that ABT-089 and ABT-107 do not affect nicotine consumption, but may reduce the likelihood that a smoking lapse will lead to relapse. PMID:25128791

  5. Relative redox reactivity of radicals from substituted carboxylic acids and glycol towards heteropoly electrolytes of molybdenum and tungsten

    International Nuclear Information System (INIS)

    The reducing ability of various radicals is manifested by the extent of reduction they cause on various well characterized heteropoly compounds serving as electron acceptors. The reducing ability of several short lived radicals produced by 60Co-?-radiolysis of aqueous solution of mono and dicarboxylic acids, glycolic acid, glycol, and aminoacids have been determined. Whereas in most cases this test given as comparative measurement of the reducing ability, reaction of the radicals with the substrates in some cases complicates the matter presenting several exceptions to the rule. This is characteristic of all efforts to correlate kinetic and thermodynamic parameters such as rate and equilibrium constants, or similar parameters that are obtained by different methods such as E1/2 and E0. (orig.) 891 HK

  6. Ascorbic Acid-Initiated Tandem Radical Cyclization of N-Arylacrylamides to Give 3,3-Disubstituted Oxindoles

    Directory of Open Access Journals (Sweden)

    Sheng Liu

    2015-08-01

    Full Text Available An ascorbic acid-promoted and metal-free tandem room temperature cyclization of N-arylacrylamides with 4-nitrobenzenediazonium generated in situ was developed. This reaction proceeds smoothly through a radical mechanism and provides an environmentally friendly alternative approach to biologically active 3-alkyl-3-benzyloxindoles, avoiding the use of excess oxidants and light irradiation.

  7. On the Origin of the Methyl Radical Loss from Deprotonated Ferulic and Isoferulic Acids: Electronic Excitation of a Transient Structure

    Science.gov (United States)

    Zhang, Xiaoping; Li, Fei; Lv, Huiqing; Wu, Yanqing; Bian, Gaofeng; Jiang, Kezhi

    2013-06-01

    Formation of radical fragments from even-electron ions is an exception to the "even-electron rule". In this work, ferulic acid (FA) and isoferulic acid (IFA) were used as the model compounds to probe the fragmentation mechanisms and the isomeric effects on homolytic cleavage. Elimination of methyl radical and CO2 are the two competing reactions observed in the CID-MS of [FA - H]- and [IFA - H]-, of which losing methyl radical violates the "even-electron rule". The relative intensity of their product ions is significantly different, and thereby the two isomeric compounds can be differentiated by tandem MS. Theoretical calculations indicate that both the singlet-triplet gap and the excitation energy decrease in the transient structures, as the breaking C-O bond is lengthened. The methyl radical elimination has been rationalized as the intramolecular electronic excitation of a transient structure with an elongating C-O bond. The potential energy diagrams, completed by the addition of the energy barrier of the radical elimination, have provided a reasonable explanation of the different CID-MS behaviors of [FA - H]- and [IFA - H]-.

  8. The formation and reaction of methyl radicals produced by direct photolysis of aqueous solutions of N-acetyl substituted aliphatic amino acids at 77 K

    International Nuclear Information System (INIS)

    Photolysis of amino acids, peptides and their derivatives leads to the formation of free radicals in these substances. The electron-spin-resonance spectra obtained directly after irradiation at 77 K were not very well resolved. They were recognizable as the superposition of the spectra of different types of photoproduced radicals. CH3 radicals are formed by U.V. irradiation if methyl groups are present in the molecule. These radicals were easily detectable because of their four line spectrum. The formation of methyl radicals and their reaction with undamaged molecules of N-acetyl-substituted amino acids have been investigated. The number of CH3 radicals present after a 30 min U.V. irradiation was higher if preceding U.V. irradiations and heat treatments were performed. The overall concentration of radicals was reduced only partially during this heat-treatment, while the CH3 radicals decayed completely. Other experiments showed that the rate of and the yield of CH3 radicals by U.V. irradiation increased with the dose of a preceding ?-irradiation. The results suggest that there are substances present which are responsible for the higher production rate of methyl radicals after a preceding treatment. It is assumed that radicals are precursors of the fast-formed CH3 radicals. (author)

  9. Hydroxyl radical induced oxidation of acetylene in oxygenated aqueous solution. The formation of a highly acidic intermediate

    International Nuclear Information System (INIS)

    Pulsed irradiation was used in a study of the action of 2.8 MeV electron pulses on aqueous solutions containing an acetylene-oxygen mixture or an acetylene-oxygen-nitrous oxide mixture in order to investigate the reactions of the beta-hydroxy-vinyl-peroxyl radical. This radical is formed from acetylene by reaction with OH followed by addition of molecular oxygen. The results show that a highly acidic intermediate is formed with a pK value of greater or equal to 2. The decay of this intermediate leads to the observed products. 6 references, 2 figures, 1 table

  10. Effect of intrachain sulfonic acid dopants on the solid-state charge mobility of a model radical polymer

    International Nuclear Information System (INIS)

    Radical polymers are an emerging class of non-conjugated, charge-conducting macromolecules that are capable of transporting charge through localized oxidation–reduction (redox) reactions that occur at the stable radical groups present as the pendant groups of the macromolecular chains. The chemical nature and oxidation state of these pendant radical groups are critical to the charge transporting abilities of radical polymers in the solid state. To date, however, the control of this chemistry has been limited to external oxidizing agents, and the concept of intramolecular dopants has not been explored fully. To this end, we have synthesized poly(2,2,6,6-tetramethylpiperidinyloxy methacrylate)-co-poly(vinylsulfonic acid sodium salt) (PTMA-co-PVS). Then, electron paramagnetic resonance spectroscopy and attenuated total reflectance-Fourier transform infrared spectroscopy are implemented to evaluate the exact chemical nature of the pendant groups as a function of the PVS intramolecular dopants and exposure of the materials to external oxidation reactions. We correlate these changes in pendant group chemistry to charge transport ability, and we establish that the inclusion of a moderate amount of PVS dopants can improve the solid-state hole mobility of the material. Conversely, a large amount of sulfonic acidic dopants can be detrimental to the transport of the polymer relative to the homopolymer PTMA. Therefore, refinement of pendant group chemistry and careful addition of intramolecular dopants can enhance the solid-state transport ability of a radical polymer system. These fundamental principles, in turn, provide a vital foothold by which to optimize the solid-state charge transporting ability of current and next-generation radical polymer designs. - Highlights: • Sulfonic acid groups are copolymerized within the backbone of radical polymer chain. • Addition of the sulfonic acid groups alters the pendant group oxidation state. • Exact oxidation states are monitored with a variety of spectroscopic techniques. • Oxidation states alter the solid-state charge transport ability of radical polymers. • Optimized intramolecular doping and oxidization reaction times are established

  11. Polyphenolic Contents and Free Radical Scavenging Potential of Extracts from Leaves of Ocimum americanum L.

    Directory of Open Access Journals (Sweden)

    A.J. Afolayan

    2013-01-01

    Full Text Available This study assessed the polyphenolic contents and antioxidant activity of ethanol, butanol and ethyl acetate extracts of Ocimum americanum leaves using in vitro models. The ability of the extracts to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH?, 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid (ABTS?+, hydrogen peroxide (H2O2, Nitric Oxide (NO and hydroxyl radical (OH? was investigated. The inhibition of lipid oxidation, reducing power, total flavonoids, phenols and flavonols contents of the extracts were also determined using spectrophotometric methods. The result revealed highest concentration of polyphenolic compounds in the ethanol extract followed by n-butanol while ethyl acetate extract contained the least concentration. Free radical scavenging potentials of the extracts were found to be proportional to their respective polyphenolic contents. This study provides evidence that O. americanum leaves contain biologically active components with effective antioxidant activity and thus could be used for the management of radical related diseases.

  12. Picosecond pulse radiolysis of highly concentrated sulfuric acid solutions: evidence for the oxidation reactivity of radical cation H2O(•+).

    Science.gov (United States)

    Ma, Jun; Schmidhammer, Uli; Mostafavi, Mehran

    2014-06-12

    Aqueous solution of sulfuric acid is used as a suitable system to investigate the reactivity of the short-lived radical cation H2O(•+) which is generated by radiation in water. Ten aqueous solutions containing sulfuric acid with concentration from 1 to 18 mol?L(-1) are studied by picosecond pulse radiolysis. The absorbance of the secondary radical SO4(•-) (or HSO4(•)) formed within the 10 ps electron pulse is measured by a pulse-probe method in the visible range. The analysis of the kinetics show that the radicals of sulfuric acid are formed within the picosecond electron pulse via two parallel mechanisms: direct electron detachment by the electron pulse and oxidation by the radical cation of water H2O(•+). In highly concentrated solution when SO4(2-) is in contact with H2O(•+), the electron transfer becomes competitive against proton transfer with another water molecule. Therefore, H2O(•+) may act as an extremely strong oxidant. The maximum radiolytic yield of scavenged H2O(•+) is estimated to be 5.3 ± 0.1 × 10(-7) mol?J(-1). PMID:24824373

  13. Effects of gamma-ray-induced free radicals on the metal content and amino acid composition of human metallothionein-1

    Indian Academy of Sciences (India)

    Lieven Goossens

    2011-06-01

    Metallothioneins (MTs), a low-mass class of metalloproteins, are characterized by a high thiolate sulphur and metal content. MTs are involved in metal homeostasis and heavy metal detoxification, and are efficient scavengers of free radicals. This article describes zinc release from human MT-1 and modification of its amino acid composition when subjected to free radicals generated during gamma ray radiolysis. The effect of gamma ray radiolysis of untreated and metal-depleted human MT-1 was tested under multiple aerobic and anaerobic conditions at increasing irradiation doses. Under all conditions, a rapid increase of serine in the early stages of irradiation was observed. Irradiation for longer times led to cysteic acid formation, except under argon atmosphere. Several other amino acid concentrations gradually decreased. Formation of limited amounts of hydroxyproline, hydroxylysine and ornithine as well as some less common derivatives such as cystathionine occurred as side-effects.

  14. Studies of cationic radicals in ?-irradiated single crystals of ?-aminoisobutyric acid and related ?-amino acids by electron spin resonance and SCF MO INDO calculation

    International Nuclear Information System (INIS)

    The cationic radical of the single crystal of ?-aminoisobutyric acid ? irradiated at 770K was identified as the deprotonated cation radical, NH2C(CH3)2COO, by X- and Q-band ESR including photobleaching measurement. The eigenvalues of the g tensor were determined to be 2.0052, 2.0021, and 2.0013. The eigenvector of g/sub max/(2.0052) is perpendicular to the molecular plane and the density axis of the unpaired electron orbital, i.e., the eigenvector of g/sub int/(2.0021), is parallel to the molecular axis (Y axis). The eigenvector of g/sub min/(2.0013) is on the molecular plane and perpendicular to the molecular axis. In addition to the hyperfine coupling by methyl protons, the hyperfine coupling by N was estimated, which is axially symmetric to the molecular axis and gives the unpaired electron density on N as 0.1 for 2p/sub y/ and 0.01 for 2s. These features were supported by SCF MO INDO calculations. The deprotonated cation radical and the hydrogen bonded cation radical, the precursor of the former, show similar unpaired electron orbitals consisting of 2p/sub y/s of the skeleton atoms, but the g anisotropy of the deprotonated cation radical is smaller compared with that of the cation radical. The cationic radicals of L-?-alanine and glycine were also similarly investigated and assigned to the deprotonated cation radicals as mentioned above

  15. Neutral and acidic products derived from hydroxyl radical-induced oxidation of arabinotriose assessed by electrospray ionisation mass spectrometry.

    Science.gov (United States)

    Moreira, Ana S P; da Costa, Elisabete V; Evtuguin, Dmitry V; Coimbra, Manuel A; Nunes, Fernando M; Domingues, M Rosário M

    2014-04-01

    The oxidation of ?-(1???5)-L-arabinotriose (Ara3), an oligosaccharide structurally related to side chains of coffee arabinogalactans, was studied in reaction with hydroxyl radicals generated under conditions of Fenton reaction (Fe(2+)/H2O2). The acidic and neutral oxidation products were separated by ligand exchange/size-exclusion chromatography, subsequently identified by electrospray ionisation mass spectrometry (ESI-MS) and structurally characterised by tandem MS (ESI-MS/MS). In acidic fraction were identified several oxidation products containing an acidic residue at the corresponding reducing end of Ara3, namely arabinonic acid, and erythronic, glyceric and glycolic acids formed by oxidative scission of the furanose ring. In neutral fractions were identified derivatives containing keto, hydroxy and hydroperoxy moieties, as well as derivatives resulting from the ring scission at the reducing end of Ara3. In both acidic and neutral fractions, beyond the trisaccharide derivatives, the corresponding di- and monosaccharide derivatives were identified indicating the occurrence of oxidative depolymerisation. The structural characterisation of these oxidation products by ESI-MS/MS allowed the differentiation of isobaric and isomeric species of acidic and neutral character. The species identified in this study may help in detection of roasting products associated with the free radical-mediated oxidation of coffee arabinogalactans. PMID:24719343

  16. Thiyl radical-induced cis-trans-isomerization of arachidonic acid inhibits prostaglandin metabolism

    International Nuclear Information System (INIS)

    Complete text of publication follows. Thiyl radicals radiolytically generated from thiophenol in methanolic solution are known to isomerise double bonds of poly-unsaturated fatty acids (PUFA). ?-irradiating of such a system containing all-cis 5,8,11,14 eicosatetraenoic acid (arachidonic acid, AA) with low doses (0.1-0.8 kGy) results in a mixture of 8 to 32% mono-trans-isomers. Here we report about the influence of mono-trans-AA on the primary steps of AA-metabolism and prostaglandin synthesis, catalysed by cyclooxygenase (COX). In the cell-free model system the reaction of COX-1 with AA was analysed by controlling the oxygen level during the enzymatic reaction. As an example, a mixture of a low quantity of mono-trans-isomerized AA (10%) and 90% all-cis-isomer exhibits a marked reduced oxygen consumption by 45%. As further proofs - the yield of reactive oxygen species (ROS) generated by the COX-coupled peroxidase reaction was detected, - and the COX-1 activity in presence of different amounts of trans-AA was characterized using a photometric assay based on the oxidation of TMPD. All these methods indicated semiquantitatively a reduced activity of COX-1, depending on the trans-isomer yield. Therefore, an inhibition of COX-1 activity by only one trans-double-bond in AA could be concluded. Furthermore, in vitro cell-line experiments were performed analysing the influence of mono-trans-isomerized AA on the activity of the cell-own COX-2. Hence, VD3-differentiated and LPS-stimulated monocyte-like cells were incubated with mono-trans-AA and ROS-production was detected by the chemiluminescence measurements mentioned above. Compared to the reaction with all-cis-AA we found a considerable lowered formation of ROS. Likewise, we obtained a reduced PGE2-expression between 15 and 40% for cells treated with 8 to 29% trans-AA. The model as well as in vivo experiments demonstrate an inhibition effect of mono-trans-AA and give rise for postulating an enzyme blocking mechanism for COX-1 and COX-2 by trans-isomers

  17. Characterization of the Peroxidase Mechanism upon Reaction of Prostacyclin Synthase with Peracetic Acid. Identification of a Tyrosyl Radical Intermediate†

    OpenAIRE

    Yeh, Hui-Chun; Gerfen, Gary J.; Wang, Jinn-Shyan; Tsai, Ah-Lim; Wang, Lee-Ho

    2009-01-01

    Prostacyclin synthase (PGIS) is a membrane-bound class III cytochrome P450 that catalyzes an isomerization of prostaglandin H2, an endoperoxide, to prostacyclin. We report here the characterization of the PGIS intermediates in reactions with other peroxides, peracetic acid (PA), and iodosylbenzene. Rapid-scan stopped-flow experiments revealed an intermediate with an absorption spectrum similar to that of compound ES (Cpd ES), which is an oxo–ferryl (Fe(IV)=O) plus a protein-derived radical. C...

  18. Mechanisms leading to oligomers and SOA through aqueous photooxidation: insights from OH radical oxidation of acetic acid

    OpenAIRE

    Tan, Y.; Y. B. Lim; K. E. Altieri; Seitzinger, S.P.; B.J. Turpin

    2011-01-01

    Previous experiments have demonstrated that the aqueous OH radical oxidation of methylglyoxal produces low volatility products including oxalate and oligomers. These products are found predominantly in the particle phase in the atmosphere, suggesting that methylglyoxal is a precursor of secondary organic aerosol (SOA). Acetic acid is an important intermediate in aqueous methylglyoxal oxidation and a ubiquitous product of gas phase photochemistry, making it a potential "aqueous" SOA precursor ...

  19. Screening for antioxidants in complex matrices using high performance liquid chromatography with acidic potassium permanganate chemiluminescence detection.

    Science.gov (United States)

    McDermott, Geoffrey P; Conlan, Xavier A; Noonan, Laura K; Costin, Jason W; Mnatsakanyan, Mariam; Shalliker, R Andrew; Barnett, Neil W; Francis, Paul S

    2011-01-17

    The use of high performance liquid chromatography with acidic potassium permanganate chemiluminescence detection to screen for antioxidants in complex plant-derived samples was evaluated in comparison with two conventional post-column radical scavenging assays (2,2-diphenyl-1-picrylhydrazyl radical (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS(+))). In this approach, acidic potassium permanganate can react with readily oxidisable compounds (potential antioxidants), post-column, to produce chemiluminescence. Using flow injection analysis, experimental parameters that afforded the most suitable permanganate chemiluminescence signal for a range of known antioxidants were studied in a univariate approach. Optimum conditions were found to be: 1×10(-3)M potassium permanganate solution containing 1% (w/v) sodium polyphosphates adjusted to pH 2 with sulphuric acid, delivered at a flow rate of 2.5 mL min(-1) per line. Further investigations showed some differences in detection selectivity between HPLC with the optimised post-column permanganate chemiluminescence detection and DPPH and ABTS(+) assays towards antioxidant standards. However, permanganate chemiluminescence detection was more sensitive. Moreover, screening for antioxidants in green tea, cranberry juice and thyme using potassium permanganate chemiluminescence offers several advantages over the traditional DPPH and ABTS(+) assays, such as faster reagent preparation and superior stability; simpler post-column reaction manifold; and greater compatibility with fast chromatographic separations using monolithic columns. PMID:21167995

  20. Pulse radiolysis studies of short-lived species in solid amino acids as precursors of radicals detected by ESR

    International Nuclear Information System (INIS)

    The aim of the study was to bring closer solid state radiation chemistry and ESR spectroscopy by looking for precursors of free radicals which give ESR signals. It has been performed using time-resolved spectrophotometry (pulse radiolysis of the solid state) and diffuse reflection spectrophotometry. Alanine has been especially considered as the most investigated amino acid, important for radiation dosimetry. Absorption of the transient (? maximum at 460 nm) is identified as the species during deamination. The stable absorption spectrum with the ? maximum at 345 nm is due to the same radical as the one detected by ESR. Other amino acids: valine, threonine, glutamine and arginine show similar behaviour: microsecond spectrum of the intermediate appears always at longer wavelengths. The transient spectrum changes into stable absorption in UV of a lower wavelength. Along with the optical spectrum, the ESR spectrum appears, of similar stability. Also, other features indicate that the same radical is responsible for both the electronic and ESR spectrum. Some amino acids, like methionine give intensive transient absorption in the microsecond range but no ESR signal, after completion of consecutive fast reactions. In that case any optical absorption is due to the stable product of radiolysis, i.e. compounds with paired electrons only. (author)

  1. Electron transfer from aromatic amino acids to guanine and adenine radical cations in pi stacked and T-shaped complexes.

    Science.gov (United States)

    Butchosa, Cristina; Simon, Sílvia; Voityuk, Alexander A

    2010-04-21

    Similar redox properties of the natural nucleobases and aromatic amino acids make it possible for electron transfer (ET) to occur between these sites in protein-nucleic acid complexes. Using DFT calculations, we estimate the ET rate from aromatic amino acid X (X = Phe, His, Tyr and Trp) to radical cations of guanine (G) and adenine (A) in dimers G-X and A-X with different arrangement of the subunits. We show that irrespective of the mutual orientation of the aromatic rings, the electronic interaction in the systems is strong enough to ensure effective ET from X to G(+) or A(+). Surprisingly, relatively high ET rates are found in T-shaped dimers. This suggests that pi stacking of nucleobases and aromatic amino acids is not required for feasible ET. In most complexes [G-X](+) and [A-X](+), we find the excess charge to be confined to a single site, either the nucleobase or amino acid X. Then, conformational changes may initiate migration of the radical cation state from the nucleobase to X and back. The ET process from Trp and Tyr to G(+) is found to be faster than deprotonation of G(+). Because the last reaction may lead to the formation of highly mutagenic species, the efficient repair of G(+) may play an important role in the protection of genomic DNA from oxidative damage. PMID:20449491

  2. E.s.r. of spin-trapped radicals in aqueous solutions of deuterated amino acids and alcohols

    International Nuclear Information System (INIS)

    Selectively deuterated compounds can be utilized in spin-trapping to obtain conclusive evidence for the structures of the trapped radicals. Radicals formed from DL-alanine-2-d1, DL-alanine-3,3,3-d3, DL-alanine-d4, glycine-d5, isopropyl-2-d1 alcohol, isopropyl-d7 alcohol and t-butyl-d9 alcohol were studied. The hydrogen abstraction, deamination and decarboxylation radicals generated from deuterated alanines were investigated by spin-trapping using t-nitrosobutane. Since nitroxides of the type XYZC-CH2-N(O)-tBu which contain an asymmetric centre next to the CH2 group exhibit unequal ?-proton splittings and temperature-dependent line width alternations, the effects of temperature on the e.s.r. spectra were studied. By these methods the structures of the trapped radicals were verified and the hyperfine coupling constants could be assigned without ambiguity. In ?-irradiated polycrystalline amino acids, the observed deuterium exchange can be conveniently surveyed by dissolution in aqueous solutions containing t-nitrosobutane. (author)

  3. AVALIAÇÃO DA ATIVIDADE ANTIOXIDANTE DE DIFERENTES CERVEJAS APLICANDO OS MÉTODOS ABTS E DPPH

    Directory of Open Access Journals (Sweden)

    G. L. FREITAS

    2009-01-01

    Full Text Available

    Os compostos fenólicos são substâncias presentes naturalmente nos vegetais que podem atuar como antioxidantes. Na cerveja desempenham um papel importante nas características sensoriais (cor, aroma e sabor e nutricionais da cerveja. O objetivo deste trabalho foi determinar o conteúdo de compostos fenólicos totais e flavonóis em diversos tipos de cervejas comercializada no Brasil, assim como determinar a capacidade antioxidante in vitro realizada por dois métodos, o radical ABTS•+ (ácido 2,2'-azino-bis (3-etilbenzotiazolin 6-sulfônico e o radical DPPH• (2,2-Difenil-1-picrilhidrazilo. Para determinar os polifenóis totais foi utilizado o método de Folin-Ciocalteau e o método DMACA para os flavanóis. Os resultados mostraram que o conteúdo de compostos fenólicos nas cervejas analisadas variou de 249,73 ± 8,44 a 808,58 ± 7,42 mg/L. A cerveja escura de trigo, apresentou os maiores valores de polifenóis totais, seguida das cervejas escura de cevada, da clara de trigo e das cervejas clara de cevada. Foram encontrados resultados significativos para atividade antioxidante aplicando o método ABTS, valores de 911,79 ± 2,21 a 3857,66 ± 6,07 Mol TEAC/L dependendo do tipo de cerveja e pelo método DPPH, de 2840,12 ± 1,09 a 4290,77± 6,19 Mol TEAC/L. O conteúdo de flavanóis (equivalente a mg catequina/L de amostra., variaram em média de 1,93 ± 0,07 mg/L a 2,79 ± 0,08 mg/L para as cervejas claras e de 2,14 ± 0,04 mg/L a 5,09 ± 0,08 mg/L para as cervejas escuras.

  4. Reaction pathway of the degradation of the p-hydroxybenzoic acid by sulfate radical generated by ionizing radiations

    International Nuclear Information System (INIS)

    The degradation of p-hydroxybenzoic acid (HBA) in aqueous solutions by ionizing radiation was studied. The phenolic pollutant was easily removed by the electron beam irradiation, as more than 80% of the initial 100 µM introduced was degraded for a dose of 600 Gy. It was shown that the addition of persulfate, producing the sulfate radical as additional reactive species, induced a change in the reaction pathway. LC–MS analyses were performed in order to identify the different by-products formed. In the absence of persulfate, the main by-product formed was 3,4-dihydroxybenzoic acid, while in presence of persulfate, 1,4-benzoquinone was detected and the hydroxylated by-products were not present. A reaction pathway of HBA degradation by hydroxyl and sulfate radicals was proposed from the identification of the chemical structure of the different by-products detected. The influences of pH and dissolved oxygen were also studied. A high decline of HBA degradation was observed at pH 11 compared to pH 4.5, this decrease was minimized in the presence of persulfate. The dissolved oxygen concentration was found to be a limiting parameter of HBA degradation, however an excess of dissolved oxygen in solution did not improve the degradation to a large extent. - Highlights: • p-Hydroxybenzoic acid (HBA) is easily removed by e-beam irradiation. • The sulfate radicals formed from persulfate induce loss of the benzoic acid skeleton. • The dissolved oxygen concentration is a limiting parameter of the HBA degradation. • The effect of pH is minimized in presence of persulfate

  5. Free Radical Scavenging Activity of Kielmeyera variabilis (Clusiaceae

    Directory of Open Access Journals (Sweden)

    Dulce Helena Siqueira Silva

    2013-02-01

    Full Text Available As part of our ongoing research on antioxidant agents from Brazilian flora, we screened the free radical scavenging activity of two extracts and eight fractions of Kielmeyera variabilis (Clusiaceae using DPPH· (2,2-diphenyl-1-picrylhydrazyl-hydrate and ABTS·+ [2,2'-azinobis(3-ethylenebenzothiazoline-6-sulfonic acid] colorimetric assays. The ethyl acetate and n-butanol fractions of the leaves of K. variabilis displayed the strongest activity (IC50 of 3.5 ± 0.3 and 4.4 ± 0.2 ?g mL?1 for DPPH· and 6.6 ± 0.4 and 3.1 ± 0.1 ?g mL?1 for ABTS·+, respectively. Chromatographic fractionation of the most potent fractions led to identification of three flavonols with previously described antioxidant activity, quercitrin (1, quercetin-3-O-b-glucoside (3, and quercetin-3-O-b-galactoside (4, and of one biflavone, podocarpusflavone A (2. This is the first time that the presence of these flavonoids in Kielmeyera variabilis has been reported.

  6. Block-gradient copolymers of styrene and acrylic acid synthesized by nitroxide-mediated radical polymerization.

    Czech Academy of Sciences Publication Activity Database

    Borisova, O.; Billon, L.; Zaremski, M.; Grassl, B.; Bakaeva, Zulfiya; Lapp, A.; Št?pánek, Petr; Borisov, O.

    Granada : European Polymer Federation, 2011. s. 513. ISBN 978-84-694-3124-5. [European Polymer Congress 2011, Congress of the Specialized Group of Polymers /12./. 26.06.2011-01.07.2011, Granada] Institutional research plan: CEZ:AV0Z40500505 Keywords : block-gradient copolymers * radical polymerization Subject RIV: CD - Macromolecular Chemistry

  7. Caracterização físico-química de polpas de frutos da Amazônia e sua correlação com a atividade anti-radical livre Physical and chemical characterization of fruit pulps from Amazonia and their correlation to free radical scavenger activity

    Directory of Open Access Journals (Sweden)

    Gisele André Baptista Canuto

    2010-12-01

    Full Text Available Características físico-químicas (cor, pH, acidez total titulável, sólidos solúveis totais, conteúdo de lipídios e umidade e níveis de compostos bioativos (ácido ascórbico, fenólicos totais foram determinados em quinze amostras de polpas de frutos procedentes da região Amazônica (abiu, acerola, açaí, araçá-boi, bacaba, bacuri, buriti, cajá, cajarana, caju, cupuaçu, graviola, murici, noni e tamarindo. A atividade de radicais livres foi avaliada pelo método de ABTS. Algumas polpas apresentaram alta potencialidade antioxidante, associada com a atividade antirradicais livres obtida e os conteúdos dos componentes bioativos como compostos fenólicos e ácido ascórbico, destacando-se acerola e acaí. O conteúdo total de compostos fenólicos foi correlacionado à capacidade antioxidante das polpas.Physical and chemical characteristics (color, pH, titratable acidity, total soluble solids, lipid content, moisture and levels of bioactive compounds (ascorbic acid, total phenolics were determined in fifteen samples of fruit pulps from Amazonia (abiu, acerola, açaí, araça-boi, bacaba, bacuri, buriti, cajá, cajarana, caju, cupuaçu, graviola, murici, noni e tamarindo. The free radical scavenger activity was evaluated by the ABTS assay. Some pulps presented high antioxidant potential, associated with the free radical scavenger activity measured and the content of bioactive components, such as phenolic compounds and ascorbic acid, especialy in acerola and açaí. The total phenolic content was correlated to antioxidant capacity of pulps.

  8. Reactivity of OH radicals with chlorobenzoic acids-A pulse radiolysis and steady-state radiolysis study

    DEFF Research Database (Denmark)

    Zona, Robert; Solar, Sonja; Getoff, Nikola; Sehested, Knud; Holcman, Jerzy

    2010-01-01

    The reactions of OH radicals with 2-, 3-, 4-chlorobenzoic acids (ClBzA) and chlorobenzene (ClBz), k(OH+substrates)=(4.5?6.2)×109 dm3 mol?1 s?1, have been studied by pulse radiolysis in N2O saturated solutions. The absorption maxima of the OH-adducts were in the range of 320?340 nm. Their decay wa...... degradation. The order for the efficiency of dehalogenation was 4->2->3-ClBzA. Several primary radiolytic products could be detected by HPLC. To evaluate the toxicity of final products a bacterial bioluminescence test was carried out....

  9. Reactivity of OH radicals with chlorobenzoic acids-A pulse radiolysis and steady-state radiolysis study

    DEFF Research Database (Denmark)

    Zona, Robert; Solar, Sonja; Getoff, Nikola; Sehested, Knud; Holcman, Jerzy

    2010-01-01

    The reactions of OH radicals with 2-, 3-, 4-chlorobenzoic acids (ClBzA) and chlorobenzene (ClBz), k(OH+substrates)=(4.5−6.2)×109 dm3 mol−1 s−1, have been studied by pulse radiolysis in N2O saturated solutions. The absorption maxima of the OH-adducts were in the range of 320−340 nm. Their decay wa...... degradation. The order for the efficiency of dehalogenation was 4->2->3-ClBzA. Several primary radiolytic products could be detected by HPLC. To evaluate the toxicity of final products a bacterial bioluminescence test was carried out....

  10. Measurments of nitrous acid, nitrate radicals, formaldehyde and nitrogen dioxide for the Southern California Air Quality Study by differential optical

    International Nuclear Information System (INIS)

    This paper reports that two rapid scanning (?3000 scan min-1) differential optical absorption spectrometers were interfaced to 25 m basepath open, multiple reflection systems operated routinely at a total optical path of 800 m at Long Beach and Claremont, CA during the 1987 Southern California Air Quality Study. These instruments permitted measurements of atmospheric concentrations of nitrous acid, nitrogen dioxide and formaldehyde at the part per billion levels, and detection of the nitrate radicals with sensitivity of several tens of parts per trillion

  11. Photoinitiated Radical Carbonylation Using [11C]Carbon Monoxide : 11C-Labelling of Aliphatic Carboxylic Acids, Esters, and Amides

    OpenAIRE

    Itsenko, Oleksiy

    2005-01-01

    One-step photoinitiated free radical carbonylation was employed for the rapid (5–7 min) labelling of aliphatic carboxylic acids, esters, and amides with a short-lived positron emitter 11C (t½ = 20.3 min) at the carbonyl position. The labelled compounds were synthesized from alkyl iodides (0.05–0.1 mmol), [11C]carbon monoxide, and appropriate nucleophiles. Decay-corrected radiochemical yields were up to 74%; conversion of [11C]carbon monoxide reached 85–90%; specific radioactivity was 158–192 ...

  12. Spectroscopic studies on the antioxidant activity of p-coumaric acid

    Science.gov (United States)

    Kiliç, Ismail; Ye?ilo?lu, Ye?im

    2013-11-01

    p-coumaric acid (4-hydroxycinnamic acid), a phenolic acid, is a hydroxyl derivative of cinnamic acid. It decreases low density lipoprotein (LDL) peroxidation and reduces the risk of stomach cancer. In vitro radical scavenging and antioxidant capacity of p-coumaric acid were clarified using different analytical methodologies such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2?-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical scavenging activity and superoxide anion radical scavenging, ferrous ions (Fe2+) chelating activity and ferric ions (Fe3+) reducing ability. p-Coumaric acid inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45 ?g/mL concentration. On the other hand, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), ?-tocopherol and ascorbic acid displayed 66.8%, 69.8%, 64.5% and 59.7% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, p-coumaric acid had an effective DPPHrad scavenging, ABTSrad + scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe3+) reducing power and ferrous ions (Fe2+) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, ?-tocopherol and ascorbic acid as references antioxidant compounds. These results suggested that p-coumaric acid can be used in the pharmacological and food industry because of these properties.

  13. E.S.R. of spin-trapped radicals in gamma-irradiated polycrystalline nucleic acid constituents and their halogenated derivatives

    International Nuclear Information System (INIS)

    Free radicals in ?-irradiated polycrystalline nucleic acid constituents and their 5-halogenated derivatives have been studied by e.s.r. and spin-trapping. After ?-irradiation at room temperature, the polycrystalline samples were dissolved in aqueous solutions of t-nitrosobutane (tNB) in the absence or presence of oxygen. For many of the nucleic acid constituents two types of radicals, -C(5)RH-C(6)H- and -C(5)R-C(6)H2-, formed by H-addition to the double bond [-C(5)R = C(6)H-] of the base, were observed, where R is -CH3 or -H. In addition, radicals formed on the sugar moiety were found for some nucleosides. When oxygen was present in the tNB solution, the relative stability of trapped radicals was changed, and thus the presence of more than one radical species could be established. For halogenated bases, the radical produced by H-abstraction from N(1) was observed, and an additional radical species formed by H-addition to the C(6) position was found for 5-fluorouracil. For halogenated nucleosides, the same spectrum was observed in all compounds except the 5-fluoroderivatives, and was assigned to the radicals produced on the sugar moiety. For 5-fluorodeoxyuridine and 5-fluorouridine, the radical formed by H-addition to the C(6) position of the base was observed. In general, the present results are in good agreement with those of previous single crystal studies, but in the case of halogenated compounds other than the 5-fluoroderivatives, it was not possible to spin-trap the ?-halo radicals which were the most prominent radicals formed from ?-irradiation of single crystals at room temperature. (author)

  14. Antioxidant activity and free radical-scavenging capacity of Gynura divaricata leaf extracts at different temperatures

    Directory of Open Access Journals (Sweden)

    Wan Chunpeng

    2011-01-01

    Full Text Available Background: Extraction temperature influences the total phenolic content (TPC, total flavonoid content (TFC of medicinal plant extracts to a great extend. TPC and TFC are the principle activity constituents present in the plant. The effects of extraction temperature on TPC, TFC and free radical-scavenging capacity of Gynura divaricata leaf extracts are worth to study. Materials and Methods: Folin-Ciocalteu and aluminum chloride colorimetric assay were used to determine the TPC and TFC of Gynura divaricata leaf extracts at different temperatures. The antioxidant and free radical-scavenging activity were measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH, 2,2-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid (ABTS and phosphomolybdenum methods. Results: TPC and TFC were significantly elevated with increasing extraction temperature (from 40°C to 100°C. However, TPC and TFC were not significantly different (P > 0.05 at the extraction temperatures 90°C and 100°C. Also, the extracts obtained at a higher temperature exhibited a significant free radical-scavenging activity compared with extraction at lower temperatures (P < 0.05. The TPCs (13.95-36.68 mg gallic acid equivalent/g dry material were highly correlated with DPPH (R2 = 0.9229, ABTS (R2 = 0.9951 free radical-scavenging capacity, and total antioxidant activity (R2 = 0.9872 evaluated by phosphomolybdenum method. Conclusion: The TPC and TFC of G. divaricata leaf was significantly influenced by the extraction temperatures, which were the main antioxidant constituents present in the G. divaricata plant.

  15. A pulse radiolysis study of the OH radical induced autoxidation of methanesulfinic acid

    DEFF Research Database (Denmark)

    Sehested, K.; Holcman, J.

    1996-01-01

    takes place. During the course of the chain oxidation a peroxyacid, presumably methaneperoxymonosulfonic acid, is formed and accumulated. This acid absorbs in the UV and eventually decays by reaction with excess methanesulfinic acid k = 5 x 10(3) M(-1) s(-1). The final product of the chain autoxidation...

  16. Characterization of the Peroxidase Mechanism upon Reaction of Prostacyclin Synthase with Peracetic Acid. Identification of a Tyrosyl Radical Intermediate†

    Science.gov (United States)

    Yeh, Hui-Chun; Gerfen, Gary J.; Wang, Jinn-Shyan; Tsai, Ah-Lim; Wang, Lee-Ho

    2010-01-01

    Prostacyclin synthase (PGIS) is a membrane-bound class III cytochrome P450 that catalyzes an isomerization of prostaglandin H2, an endoperoxide, to prostacyclin. We report here the characterization of the PGIS intermediates in reactions with other peroxides, peracetic acid (PA), and iodosylbenzene. Rapid-scan stopped-flow experiments revealed an intermediate with an absorption spectrum similar to that of compound ES (Cpd ES), which is an oxo–ferryl (Fe(IV)=O) plus a protein-derived radical. Cpd ES, formed upon reaction with PA, has an X-band (9 GHz) EPR signal of g = 2.0047 and a half-saturation power, P1/2, of 0.73 mW. High-field (130 GHz) EPR reveals the presence of two species of tyrosyl radicals in Cpd ES with their g-tensor components (gx, gy, gz) of 2.00970, 2.00433, 2.00211 and 2.00700, 2.00433, 2.00211 at a 1:2 ratio, indicating that one is involved in hydrogen bonding and the other is not. The line width of the g = 2 signal becomes narrower, while its P1/2 value becomes smaller as the reaction proceeds, indicating migration of the unpaired electron to an alternative site. The rate of electron migration (~0.2 s?1) is similar to that of heme bleaching, suggesting the migration is associated with the enzymatic inactivation. Moreover, a g = 6 signal that is presumably a high-spin ferric species emerges after the appearance of the amino acid radical and subsequently decays at a rate comparable to that of enzymatic inactivation. This loss of the g = 6 species thus likely indicates another pathway leading to enzymatic inactivation. The inactivation, however, was prevented by the exogenous reductant guaiacol. The studies of PGIS with PA described herein provide a mechanistic model of a peroxidase reaction catalyzed by the class III cytochromes P450. PMID:19187034

  17. Reactivity of OH radicals with chlorobenzoic acids-A pulse radiolysis and steady-state radiolysis study

    Energy Technology Data Exchange (ETDEWEB)

    Zona, Robert [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Solar, Sonja, E-mail: sonja.solar@univie.ac.a [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Getoff, Nikola [University of Vienna, Department of Nutritional Sciences, Section Radiation Biology, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Sehested, Knud; Holcman, Jerzy [RISO National Laboratory Environmental Science and Technology Department, DK-4000, Roskilde (Denmark)

    2010-05-15

    The reactions of OH radicals with 2-, 3-, 4-chlorobenzoic acids (ClBzA) and chlorobenzene (ClBz), k({sup c}entre dotOH+substrates)=(4.5-6.2)x10{sup 9} dm{sup 3} mol{sup -1} s{sup -1}, have been studied by pulse radiolysis in N{sub 2}O saturated solutions. The absorption maxima of the OH-adducts were in the range of 320-340 nm. Their decay was according to a second-order reaction, 2k=(1-9)x10{sup 8} dm{sup 3} mol{sup -1} s{sup -1}. In the presence of N{sub 2}O/O{sub 2} the formation of peroxyl radicals was detectable for 2-, 4-ClBzA and ClBz, k(OH-adduct+O{sub 2})=(2-4)x10{sup 7} dm{sup 3} mol{sup -1} s{sup -1}, while this reaction for 3-ClBzA was too slow to be registered. In the presence of N{sub 2}O the degradation rates induced by gamma radiation were very similar for all chlorobenzoic acids, yet the chloride formation was distinctly higher for 3-ClBzA. In the presence of oxygen the initial degradation of 2-and 4-ClBzA equaled the OH-radical concentration, whereas in case of 3-ClBzA only approx60% of {sup c}entre dotOH led to degradation. The order for the efficiency of dehalogenation was 4->2->3-ClBzA. Several primary radiolytic products could be detected by HPLC. To evaluate the toxicity of final products a bacterial bioluminescence test was carried out.

  18. Reactivity of OH radicals with chlorobenzoic acids-A pulse radiolysis and steady-state radiolysis study

    DEFF Research Database (Denmark)

    Zona, Robert; Solar, Sonja

    2010-01-01

    The reactions of OH radicals with 2-, 3-, 4-chlorobenzoic acids (ClBzA) and chlorobenzene (ClBz), k(OH+substrates)=(4.5?6.2)×109 dm3 mol?1 s?1, have been studied by pulse radiolysis in N2O saturated solutions. The absorption maxima of the OH-adducts were in the range of 320?340 nm. Their decay was according to a second-order reaction, 2k=(1?9)×108 dm3 mol?1 s?1. In the presence of N2O/O2 the formation of peroxyl radicals was detectable for 2-, 4-ClBzA and ClBz, k(OH-adduct+O2)=(2?4)×107 dm3 mol?1 s?1, while this reaction for 3-ClBzA was too slow to be registered. In the presence of N2O the degradation rates induced by gamma radiation were very similar for all chlorobenzoic acids, yet the chloride formation was distinctly higher for 3-ClBzA. In the presence of oxygen the initial degradation of 2-and 4-ClBzA equaled the OH-radical concentration, whereas in case of 3-ClBzA only 60% of OH led to degradation. The order for the efficiency of dehalogenation was 4->2->3-ClBzA. Several primary radiolytic products could be detected by HPLC. To evaluate the toxicity of final products a bacterial bioluminescence test was carried out.

  19. Tropospheric chemistry of natural hydrocarbons, aldehydes, and peroxy radicals: Their connections to sulfuric acid production and climate effects

    International Nuclear Information System (INIS)

    Recent work has shown that natural hydrocarbon emissions can significantly affect the levels of urban and regional tropospheric ozone. We report on the reactivities of these biogenic trace gases, particularly isoprene, focusing on their importance in the production of aldehydes and peroxy radicals, leading to increased levels of hydrogen over regional forests. Hydrogen peroxide can lead to the wet oxidation of sulfur dioxide to acidic sulfate in aerosols, fogs, and clouds. In turn, acidic sulfate can act to as a light scattering aerosol and a source of cloud condensation nuclei (CCN), potentially leading to global cooling. Aerosol sulfate and other dissolved organic and inorganic compounds can also play important roles as a greenhouse species in the lower troposphere

  20. Immobilized transition metal-based radical scavengers and their effect on durability of Aquivion® perfluorosulfonic acid membranes

    Science.gov (United States)

    D'Urso, C.; Oldani, C.; Baglio, V.; Merlo, L.; Aricò, A. S.

    2016-01-01

    A simple and broadly applicable preparation procedure to obtain silica-supported transition metal (namely Cr, Co and Mn)-based radical scavengers, containing sulfonic acid functionalities, is reported. These systems are widely characterised in terms of structure, bulk and surface composition and morphology by X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), X-Ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM). The scavenger material is loaded in ePTFE reinforced membranes prepared from Aquivion® perfluorosulfonic acid (PFSA) dispersions. All these composite membranes show longer lifetime in Accelerated Stress Tests (AST) and reduced fluoride release in Fenton's tests than the scavenger-free membranes without any loss in electrochemical performance. The Cr-scavenger-based polymer electrolyte shows a three-time larger stability than the pristine membrane.

  1. Chemical Constituents with Free-Radical-Scavenging Activities from the Stem of Microcos paniculata

    Directory of Open Access Journals (Sweden)

    Yu Chen

    2010-08-01

    Full Text Available The free-radical-scavenging activities of various solvent extracts of Microcos paniculata were evaluated through in vitro model systems, such as 1,1-diphenyl-2-picrylhydrazyl (DPPH, 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonate (ABTS and Co (II EDTA-induced luminol chemiluminescence by flow injection. In all three of these systems the ethyl acetate (EtOAc extract showed the highest free-radical-scavenging activity compared with the other three (n-BuOH, water and petroleum ether extracts. Free-radical-scavenging assay-guided chromatographic separation of the EtOAc extract, using a normal-phase and reverse-phase silica gel column chromatography yielded five compounds: a new triterpene named methyl 3b-O-p-hydroxy-E-cinnamoyloxy-2a,23-dihydroxyolean-12-en-28-oate (1, whose spectral data are presented for the first time, together with four known compounds, epicatechin (2, 3-trans-feruloyl maslinic acid (3, maslinic acid (4 and sucrose (5. All of the compounds were isolated from Microcos paniculata for the first time. The compounds were identified by spectroscopic methods. Among them, compound 2 displayed significant free-radical-scavenging activity which is similar to that of standard antioxidant ascorbic acid (VC and therefore may be a promising natural antioxidant.

  2. Neuroprotective and free radical scavenging activities of phenolic compounds from Hovenia dulcis.

    Science.gov (United States)

    Li, Gao; Min, Byung-Sun; Zheng, Changji; Lee, Joongku; Oh, Sei-Ryang; Ahn, Kyung-Seop; Lee, Hyeong-Kyu

    2005-07-01

    The EtOAc-soluble fraction from a methanolic extract of Hovenia dulcis Thunb. exhibited neuroprotective activity against glutamate-induced neurotoxicity in mouse hippocampal HT22 cells. The neuroprotective activity-guided isolation resulted in 8 phenolic compounds (1-8), such as vanillic acid (1), ferulic acid (2), 3,5-dihydroxystilbene (3), (+)-aromadendrin (4), methyl vanillate (5), (-)-catechin (6), 2,3,4-trihydrobenzoic acid (7), and (+)-afzelechin (8). Among these, compounds 6 and 8 had a neuroprotective effect on the glutamate-induced neurotoxicity in HT22 cells. Furthermore, compound 6 had a DPPH free radical scavenging effect with an IC50 value of 57.7 microM, and a superoxide anion radical scavenging effect with an IC50 value of 8.0 microM. Both compounds 6 and 8 had ABTS cation radical scavenging effects with IC50 values of 7.8 microM and 23.7 microM, respectively. These results suggest that compounds 6 and 8 could be neuroprotectants owing to their free radical scavenging activities. PMID:16114495

  3. beta-Scission of C-3 (beta-carbon) alkoxyl radicals on peptides and proteins : a novel pathway which results in the formation of alpha-carbon radicals and the loss of amino acid side chains

    DEFF Research Database (Denmark)

    Headlam, H A; Mortimer, A

    2000-01-01

    Exposure of proteins to radicals in the presence of O(2) brings about multiple changes in the target molecules. These alterations include oxidation of side chains, fragmentation, cross-linking, changes in hydrophobicity and conformation, altered susceptibility to proteolytic enzymes, and formation of new reactive groups, including hydroperoxides. These processes can result in the loss of structural or enzymatic activity. Backbone fragmentation is known to occur via a number of mechanisms, most of which involve hydrogen abstraction from the alpha-carbon site on the backbone. In this study, we demonstrate that initial attack at a side chain site, the beta-position (C-3), can give rise to formation of alpha-carbon radicals, and hence backbone cleavage, via the formation and subsequent beta-scission of C-3 alkoxyl radicals. This beta-scission reaction is rapid (k estimated to be >10(7) s(-)(1)) even with primary alkoxyl radicals derived from Ala residues, and occurs when the alkoxyl radicals are generated from a variety of precursors, including hydroperoxides and nitrate esters. These reactions release the former side chain as a reactive aldehyde or ketone; thus, Ala peptides release high yields of methanal (formaldehyde). This product has been quantified with a number of oxidized peptides and proteins, and can account for up to 64% of the initial attacking radicals with some Ala peptides. When quantified together with the hydroperoxide precursors, these species account for up to 80% of the initial radicals, confirming that this is a major process. Methanal causes cell toxicity and DNA damage and is an animal carcinogen and a genotoxic agent in human cells. Thus, the formation and subsequent reaction of alkoxyl radicals formed at the C-3 position on aliphatic amino acid side chains on peptides and proteins can give rise to both backbone fragmentation and the release of further reactive species which can cause cell toxicity and mutagenicity.

  4. Toxicological Evaluation of Emblica officinalis Fruit Extract and its Anti-inflammatory and Free Radical Scavenging Properties

    Science.gov (United States)

    Middha, Sushil Kumar; Goyal, Arvind Kumar; Lokesh, Prakash; Yardi, Varsha; Mojamdar, Lavanya; Keni, Deepthi Sudhir; Babu, Dinesh; Usha, Talambedu

    2015-01-01

    Background: Emblica officinalis (Euphorbiaceae), popularly known as Indian gooseberry or “Amla” in India, is used in Ayurveda as “rejuvenating herb” since ancient times. Objective: This study was carried out to estimate toxicity, anti-inflammatory, and antioxidative activities of the methanolic extract of Emblica officinalis fruit (MEO) in an animal model. Materials and Methods: Antioxidative property of MEO was assessed by in vitro assays such as phosphomolybdenum assay (total antioxidant capacity), free radical scavenging assays 1,1-diphenyl-2-picrylhydrazyl and 2,2’-azino-bis and 3-ethylbenzthiazoline-6-sulphonic acid (DPPH and ABTS method) and lipid peroxidation assay (LPO). The anti-inflammatory property was evaluated by carrageenan-induced acute inflammation in rats by measuring rat paw volume at different time intervals and toxicological analysis using mice. Results and Discussion: High performance liquid chromatography studies revealed the presence of gallic acid (2.10%), mucic acid (4.90%), ellagic acid (2.10%), quercetin (28.00%), rutin (3.89%), and ?-glucogallin (1.46%). MEO showed highest antioxidant activities by using DPPH (17.33–89.00%), ABTS (23.03–94.16%), nitric oxide scavenging activity (12.94–70.16%), LPO (56.54%), and phosphomolybdenum assay (142 ± 6.09 ?g/ml). The LD50 was found to be approximately 1125 mg/kg (p.o). High dose of MEO showed significant reduction (72.71%) in the inflammation after 4 h of treatment, which was comparable to diclofenac (10 mg/kg) (61.57%) treated group. Significant reduction (P phenolic compounds of MEO may serve as a potential herbal drug for amelioration of acute inflammation due to their modulatory action on free radicals. SUMMARY The methanolic extract of Emblica officinalis fruit (MEO) has potent antioxidant activity as assessed by DPPH, ABTS and LPO assaysMEO has potent anti-inflammatory activity in carrageenan induced paw edema modelThe phenolic compounds of MEO might be a potential herbal drug for amelioration of acute inflammation. Abbreviations used: ROS, reactive oxygen species; RNS, reactive nitrogen species, LPO, lipid peroxidation, NO, nitric oxide, IL, interleukin; TNF ? tumor necrosis factor alpha; NSAIDs, nonsteroidal anti inflammatory drugs; AA, ascorbic acid; MEO, methanolic extract of Emblica officinalis fruit; ABTS+; 2,2’ azino bis 3 ethylbenzthiazoline 6 sulphonic acid; DPPH, 1,1 diphenyl 2 picrylhydrazyl; HPLC, high performance liquid chromatography; MDA, malondialdehyde; DMSO, dimethyl sulphoxide; ELISA, enzyme linked immunosorbent assay.

  5. Peroxyacetic acid in urban and rural atmosphere: concentration, feedback on PAN-NOx cycle and implication on radical chemistry

    Directory of Open Access Journals (Sweden)

    J. L. Li

    2009-10-01

    Full Text Available Peroxyacetic Acid (PAA is one of important atmospheric organic peroxides, which have received increasing attention for their potential contribution to the oxidation capacity of the troposphere and the formation of secondary aerosols. We report here that, for the first time, a series of data for atmospheric PAA concentrations at urban and rural sites, from five field campaigns carried out in China in summer 2006, 2007 and 2008. For these five measurements, daytime mean PAA concentrations on sunlit days were 0.02–0.14 ppbv with a maximum level of ~1 ppbv. The various meteorological and chemical parameters influencing PAA concentrations were examined using the Principal Factor Analysis. This statistical analysis shows that the local photochemical production was the major source of PAA, and its concentration increased with increasing temperature, solar radiation and ozone but decreased with increasing NOx (NO and NO2, CO, SO2, and relative humidity. Based on the dataset, several issues are highlighted in this study: (i because PAA is a product from the photochemical oxidation of some specific volatile organic compounds (VOCs that lead to acetyl peroxy radicals, the importance of various VOCs with respect to the PAA formation is therefore ranked using the incremental reactivity method. (ii The contribution of PAN thermal degradation to PAA formation under conditions of different NOx concentrations is estimated based on the chemical kinetics analysis. The result shows that PAN seems to play an important role in the formation of PAA when the NO/NO2 concentration ratio was less than 0.2 and PAA would correspondingly have feedback on the PAN-NOx cycle. (iii PAA and other peroxides, such as methyl hydroperoxide (MHP and H2O2, usually exhibited a similar asymmetric shape typically shifted to the afternoon. However, at a high SO2 level, H2O2 showed a profile different from those of MHP and PAA. The combination of linear regression and chemical kinetics analysis reveals that a possible unknown pathway results in the significant removal of H2O2 and the extent of H2O2 undergoing this pathway needs a further study. (iv Considering that PAA is the reservior of free radicals, its fate is expected to have an effect on the free radical budget in the atmosphere. A box model based on the CBM-IV mechanism has been performed to access its influence on the radical budget. We suggest that the detailed information on PAA in the atmosphere is of importance to better understand the free radical chemistry.

  6. Peroxyacetic acid in urban and rural atmosphere: concentration, feedback on PAN-NOx cycle and implication on radical chemistry

    Science.gov (United States)

    Zhang, X.; Chen, Z. M.; He, S. Z.; Hua, W.; Zhao, Y.; Li, J. L.

    2010-01-01

    Peroxyacetic acid (PAA) is one of the most important atmospheric organic peroxides, which have received increasing attention for their potential contribution to the oxidation capacity of the troposphere and the formation of secondary aerosols. We report here, for the first time, a series of data for atmospheric PAA concentrations at urban and rural sites, from five field campaigns carried out in China in summer 2006, 2007 and 2008. For these five measurements, daytime mean (08:00-20:00 LT) PAA concentrations on sunlit days were 21.4-148.0 pptv with a maximum level of ~1 ppbv. The various meteorological and chemical parameters influencing PAA concentrations were examined using Principal Factor Analysis. This statistical analysis shows that the local photochemical production was the major source of PAA, and its concentration increased with increasing temperature, solar radiation and ozone but decreased with increasing NOx (NO and NO2), CO, SO2, and relative humidity. Based on the dataset, several issues are highlighted in this study: (i) Because PAA is a product from the photochemical oxidation of some specific volatile organic compounds (VOCs) that lead to acetyl peroxy radicals, the importance of various VOCs with respect to the PAA formation is therefore ranked using the incremental reactivity method. (ii) The contribution of PAN thermal degradation to PAA formation under conditions of different NOx concentrations is estimated based on the chemical kinetics analysis. The result shows that PAN seems to play an important role in the formation of PAA when the NO/NO2 concentration ratio was less than 0.2 and PAA would correspondingly have feedback on the PAN-NOx cycle. (iii) PAA and other peroxides, such as methyl hydroperoxide (MHP) and H2O2, usually exhibited a similar asymmetric shape typically shifted to the afternoon. However, under some conditions, H2O2 diurnal cycle was out of phase with MHP and PAA. The combination of linear regression and kinetics analysis indicate that the formation and removal processes of H2O2 may be different from those of MHP and PAA. (iv) Considering that PAA is the reservior of free radicals, its fate is expected to have an effect on the free radical budget in the atmosphere. A box model based on the CBM-IV mechanism has been performed to access its influence on the radical budget. We suggest that the detailed information on PAA in the atmosphere is of importance to better understand the free radical chemistry.

  7. Peroxyacetic Acid in Urban and Rural Atmosphere: Feedback on PAN-NO-NO2 Cycle and Implication on Radical Chemistry

    Science.gov (United States)

    Chen, Z.; Zhang, X.

    2009-12-01

    Peroxyacetic Acid (PAA) is one of important atmospheric organic peroxides, which have received increasing attention for their contribution to the oxidizing power of the troposphere and the formation of secondary sulfate and organic aerosols. We report here, for the first time, a series of data of atmospheric PAA concentrations at urban and rural sites, from five field campaigns carried out in China in summer 2006, 2007 and 2008. For these five measurements, daytime mean PAA concentrations on sunlit days were 0.02 to 0.14 ppbv with a maximum level of ~ 1 ppbv. The various meteorological and chemical parameters influencing PAA concentrations were examined using the Principal Factor Analysis. This statistical analysis shows that the local photo-chemical production was the major source of PAA, and its concentration increased with increasing temperature, solar radiation and ozone but decreased with increasing NOx (NO and NO2), CO, SO2, and relative humidity. Because PAA is a product from the photo-chemical oxidation of some specific volatile organic compounds (VOCs) that lead to acetyl peroxy radicals, the importance of various VOCs with respect to the PAA formation was therefore ranked using the incremental reactivity method. Moreover, the contribution of PAN thermal degradation to PAA formation under different NOx concentrations was estimated using a chemical kinetics analysis. The result shows that PAN played an important role in the formation of PAA when NO/NO2 concentration ratio was less than 0.2 and PAA would correspondingly give a feedback on the PAN-NO-NO2 cycle by consuming acetyl peroxy radicals. Like other peroxides measured in these campaigns, such as methyl hydroperoxide (MHP) and H2O2, PAA usually exhibited an asymmetric shape typically shifted to the afternoon. However, under a high SO2 level, H2O2 showed a different trend from MHP and PAA. The combination of linear regression and chemical kinetics analysis reveals that a potentially unknown pathway results in the significant removal of H2O2 and the extent of H2O2 undergoing this pathway needs a further study. Considering that PAA is both source and sink of free radicals, its fate is expected to have an effect on the free radical burden in the atmosphere. A box model based on the CBM-IV mechanism has been employed to make a preliminary estimation on this effect. We suggest that the detailed information on PAA in the atmosphere is of importance to better understand the free radical chemistry.

  8. Peroxyacetic acid in urban and rural atmosphere: concentration, feedback on PAN-NOx cycle and implication on radical chemistry

    Directory of Open Access Journals (Sweden)

    J. L. Li

    2010-01-01

    Full Text Available Peroxyacetic acid (PAA is one of the most important atmospheric organic peroxides, which have received increasing attention for their potential contribution to the oxidation capacity of the troposphere and the formation of secondary aerosols. We report here, for the first time, a series of data for atmospheric PAA concentrations at urban and rural sites, from five field campaigns carried out in China in summer 2006, 2007 and 2008. For these five measurements, daytime mean (08:00–20:00 LT PAA concentrations on sunlit days were 21.4–148.0 pptv with a maximum level of ~1 ppbv. The various meteorological and chemical parameters influencing PAA concentrations were examined using Principal Factor Analysis. This statistical analysis shows that the local photochemical production was the major source of PAA, and its concentration increased with increasing temperature, solar radiation and ozone but decreased with increasing NOx (NO and NO2, CO, SO2, and relative humidity. Based on the dataset, several issues are highlighted in this study: (i Because PAA is a product from the photochemical oxidation of some specific volatile organic compounds (VOCs that lead to acetyl peroxy radicals, the importance of various VOCs with respect to the PAA formation is therefore ranked using the incremental reactivity method. (ii The contribution of PAN thermal degradation to PAA formation under conditions of different NOx concentrations is estimated based on the chemical kinetics analysis. The result shows that PAN seems to play an important role in the formation of PAA when the NO/NO2 concentration ratio was less than 0.2 and PAA would correspondingly have feedback on the PAN-NOx cycle. (iii PAA and other peroxides, such as methyl hydroperoxide (MHP and H2O2, usually exhibited a similar asymmetric shape typically shifted to the afternoon. However, under some conditions, H2O2 diurnal cycle was out of phase with MHP and PAA. The combination of linear regression and kinetics analysis indicate that the formation and removal processes of H2O2 may be different from those of MHP and PAA. (iv Considering that PAA is the reservior of free radicals, its fate is expected to have an effect on the free radical budget in the atmosphere. A box model based on the CBM-IV mechanism has been performed to access its influence on the radical budget. We suggest that the detailed information on PAA in the atmosphere is of importance to better understand the free radical chemistry.

  9. Radical-mediated dehydrogenation of bile acids by means of hydrogen atom transfer to triplet carbonyls.

    Science.gov (United States)

    Miro, P; Marin, M L; Miranda, M A

    2016-02-24

    The aim of the present paper is to explore the potential of radical-mediated dehydrogenation of bile salts (BSs), which is reminiscent of the enzymatic action of hydroxysteroid dehydrogenase enzymes (HSDH). The concept has been demonstrated using triplet carbonyls that can be efficiently generated upon selective UVA-excitation. Hydrogen atom transfer (HAT) from BSs to triplet benzophenone (BP) derivatives gave rise to radicals, ultimately leading to reduction of the BP chromophore with concomitant formation of the oxo-analogs of the corresponding BSs. The direct reactivity of triplet BP with BSs in the initial step was evaluated by determining the kinetic rate constants using laser flash photolysis (LFP). The BP triplet decay was monitored (?max = 520 nm) upon addition of increasing BS concentrations, and the obtained rate constant values indicated a reactivity of the methine hydrogen atoms in the order of C-3 kinetics of the overall process, monitored through the disappearance of the typical BP absorption band at 260 nm, was much faster under N2 than under O2, also supporting the role of the oxygen-quenchable triplet in the dehydrogenation process. Furthermore, irradiation of deaerated aqueous solutions of sodium cholate in the presence of KPMe provided the oxo-analogs, 3[O],7[O]-CA, 3[O]-CA and 7[O]-CA, arising from the HAT process. PMID:26833240

  10. Free radical grafting of gallic acid (GA) on cellulose nanocrystals (CNCS) and evaluation of antioxidant reinforced gellan gum films

    Science.gov (United States)

    Criado, P.; Fraschini, C.; Salmieri, S.; Becher, D.; Safrany, A.; Lacroix, M.

    2016-01-01

    Antiradical properties were introduced on cellulose nanocrystals (CNCs) by redox pair (RP) initiator and γ-radiation treatments. Different procedures were tested on CNC, first a 2 h reaction of hydrogen peroxide (H2O2)/ascorbic acid (AA) was performed on CNC solution. γ-Radiation treatment at 20 kGy dose was then applied and immediately after GA was reacted during 24 h with the pretreated CNCs, giving CNC-H2O2-AA-γ-GA. The formation of new carboxylic acids and carbonyl groups were characterized by FT-IR at 1650 and 1730 cm-1 respectively. Carboxylic acid functionalities were also analyzed by conductometric titration where an increase from 49 to 134 mmol COOH kg-1 was found from native to irradiated CNCs. A similar increase in the carboxylic acid content (132 mmol kg-1) was observed for CNC-H2O2-AA-γ-GA, showing the highest radical scavenging properties (8 mM Trolox eq/mg CNC). Thermogravimetric analysis confirmed the structural changes onto CNC. Film packaging containing 20% of CNC-H2O2-AA-γ-GA was then added to a gellan-based film packaging. A significant improvement (pCNC-H2O2-AA-γ-GA was added to the film packaging formulation.

  11. Norcantharidin enhances ABT-737-induced apoptosis in hepatocellular carcinoma cells by transcriptional repression of Mcl-1.

    Science.gov (United States)

    Zhang, Shuijun; Li, Gongquan; Ma, Xiuxian; Wang, Yu; Liu, Guangzhi; Feng, Liushun; Zhao, Yongfu; Zhang, Gong; Wu, Yang; Ye, Xuexiang; Qin, Baoming; Lu, Jianfeng

    2012-09-01

    Small-molecule cell-permeable Bcl-2/Bcl-xL antagonist ABT-737 has recently emerged as a novel cancer therapeutic agent because it potently induces apoptosis in certain cancer cells. However, since ABT-737 binds to Mcl-1 with low affinity, ABT-737-mediated apoptosis signaling is inhibited in hepatocellular carcinoma (HCC) cells and other solid cancer cells due to the elevated expression of Mcl-1. Accordingly, strategies that target Mcl-1 are explored for overcoming ABT-737-resistance. In this study, we reported that Norcantharidin (NCTD), a small-molecule anticancer drug derived from Chinese traditional medicine blister beetle (Mylabris), induced transcriptional repression of Mcl-1 and considerably enhanced ABT-737-triggered cell viability inhibition and apoptosis in multiple HCC cell lines. Moreover, we observed that the enhancement of ABT-737-mediated apoptosis by NCTD was associated with activation of mitochondrial apoptosis signaling pathway, which involved cytosolic release of cytochrome c, cleavage of caspase-9 and caspase-3. Additionally, knockdown of Bax/Bak, the key effectors permeabilizing mitochondrial outer membrane significantly attenuated the enhancement, indicating mitochondrial apoptosis pathway played an essential role in the execution of the apoptosis. Finally, knockdown of Mcl-1 substantially potentiated ABT-737-mediated apoptotic cell death, confirming the potency of Mcl-1 repression by NCTD in enhancing ABT-737-induced apoptosis. These results therefore suggest that combination treatment with NCTD can overcome ABT-737 resistance and enhance ABT-737 therapeutic efficacy in treating human HCC. PMID:22609455

  12. Automatic flow system for sequential determination of ABTS*+ scavenging capacity and Folin-Ciocalteu index: a comparative study in food products.

    Science.gov (United States)

    Magalhães, Luís M; Segundo, Marcela A; Reis, Salette; Lima, José L F C; Tóth, Ildikó V; Rangel, António O S S

    2007-06-01

    In the present work, an automatic flow procedure for the sequential spectrophotometric determination of Folin-Ciocalteu reducing capacity (FC assay) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS*+) scavenging capacity expressed as the trolox equivalent (TEAC assay) is proposed for a comparative study of antioxidant properties in food products. Exploiting the flexibility of flow management associated to the computer control offered by multisyringe flow injection analysis, both methodologies were carried out in the same manifold using gallic acid and trolox as standard compounds. The proposed system configuration allowed the performance of each method separately or in tandem, providing 24 determinations per hour, which accounts for its application in routine analysis. The present methodology was applied to a large number of beverages (n=72), namely red and white wines, herbal and tea infusions, juices and beers. The results obtained showed that FC reducing capacity and TEAC values of red wines were significantly different from those obtained for the other beverages, while tea infusions provided significantly higher TEAC values when compared to white wines, herbal infusions, juices and beers. A good correlation was found between TEAC and FC reducing capacity (R>0.9) for red wines, herbal and tea infusions, and beers. For these beverages, similar slope values were found (106-140 mg L(-1) of gallic acid per mM of Trolox), except for beers that showed a higher response for FC assay. These results provided evidence that the correlation between these assays vary according to the type of sample, reinforcing the idea that more than one method should be used for evaluation of antioxidant capacity. PMID:17512826

  13. Sulfate radical-induced degradation of Acid Orange 7 by a new magnetic composite catalyzed peroxymonosulfate oxidation process

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Dan; Ma, Xiaolong; Zhou, Jizhi [School of Environmental and Chemical Engineering, Shanghai University, No. 99 Shangda Road, Shanghai 200444 (China); Chen, Xi [Department of Earth and Environmental Engineering, Columbia University, West 120th Street, New York, NY 10027 (United States); Qian, Guangren, E-mail: grqian@shu.edu.cn [School of Environmental and Chemical Engineering, Shanghai University, No. 99 Shangda Road, Shanghai 200444 (China)

    2014-08-30

    Graphical abstract: Organic dyes could be absorbed on the surface of the composite or dispersed in the solution. Sulfate radicals (SO{sub 4}·{sup ?}) generated by the synergistic reaction between peroxymonosulfate (PMS) and the composite, attacked the organic functional groups of the dyes molecules both adsorbed on the composite surface and dispersed in the solution, which resulted in the degradation of AO7 dye. - Highlights: • A new composite was synthesized successfully via microwave hydrothermal method. • The complete degradation in the system of FLCN and PMS can be achieved. • The catalytic behavior of FLCN can be reused at least for five times. • The AO7 degradation mechanism in the system of FLCN and PMS was demonstrated. - Abstract: We synthesized a novel magnetic composite, Fe{sub 3}O{sub 4}/Cu(Ni)Cr-LDH, as a heterogeneous catalyst for the degradation of organic dyes in the solution using sulfate radical-based advanced oxidation processes. The physicochemical properties of the composite synthesized via two-step microwave hydrothermal method were characterized by several techniques, such as X-ray diffraction (XRD), inductively coupled plasma (ICP), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The degradation tests were performed at 25 °C with Acid Orange 7 (AO7) initial concentration of 25 mg/L and AO7/peroxymonosulfate (PMS) molar ratio of 1:10, which showed that the complete degradation by Fe{sub 3}O{sub 4}/Cu{sub 1.5}Ni{sub 0.5}Cr-LDH could be achieved and the mineralization rate could reach 46%. PMS was activated by Cu (II) and Fe (II/III) of Fe{sub 3}O{sub 4}/Cu(Ni)Cr-LDH to generate sulfate radicals (SO{sub 4}·{sup ?}). Subsequently, the organic functional groups of AO7 molecules were destroyed by sulfate radicals (SO{sub 4}·{sup ?}), inducing the degradation of AO7. Moreover, the catalytic behavior of the catalysts could be reused five times. Therefore, our work suggested that the Fe{sub 3}O{sub 4}/Cu(Ni)Cr-LDH composite could be applied widely for the treatment of organic dyes in wastewater.

  14. Sulfate radical-induced degradation of Acid Orange 7 by a new magnetic composite catalyzed peroxymonosulfate oxidation process

    International Nuclear Information System (INIS)

    Graphical abstract: Organic dyes could be absorbed on the surface of the composite or dispersed in the solution. Sulfate radicals (SO4·?) generated by the synergistic reaction between peroxymonosulfate (PMS) and the composite, attacked the organic functional groups of the dyes molecules both adsorbed on the composite surface and dispersed in the solution, which resulted in the degradation of AO7 dye. - Highlights: • A new composite was synthesized successfully via microwave hydrothermal method. • The complete degradation in the system of FLCN and PMS can be achieved. • The catalytic behavior of FLCN can be reused at least for five times. • The AO7 degradation mechanism in the system of FLCN and PMS was demonstrated. - Abstract: We synthesized a novel magnetic composite, Fe3O4/Cu(Ni)Cr-LDH, as a heterogeneous catalyst for the degradation of organic dyes in the solution using sulfate radical-based advanced oxidation processes. The physicochemical properties of the composite synthesized via two-step microwave hydrothermal method were characterized by several techniques, such as X-ray diffraction (XRD), inductively coupled plasma (ICP), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The degradation tests were performed at 25 °C with Acid Orange 7 (AO7) initial concentration of 25 mg/L and AO7/peroxymonosulfate (PMS) molar ratio of 1:10, which showed that the complete degradation by Fe3O4/Cu1.5Ni0.5Cr-LDH could be achieved and the mineralization rate could reach 46%. PMS was activated by Cu (II) and Fe (II/III) of Fe3O4/Cu(Ni)Cr-LDH to generate sulfate radicals (SO4·?). Subsequently, the organic functional groups of AO7 molecules were destroyed by sulfate radicals (SO4·?), inducing the degradation of AO7. Moreover, the catalytic behavior of the catalysts could be reused five times. Therefore, our work suggested that the Fe3O4/Cu(Ni)Cr-LDH composite could be applied widely for the treatment of organic dyes in wastewater

  15. Identification of essential amino-acid residues in Azotobacter vinelandii isocitrate dehydrogenase by radical anions and H atoms

    International Nuclear Information System (INIS)

    Pure TPN+-specific isocitrate dehydrogenase from Azotobacter vinelandii was irradiated with H atoms generated in a ?-irradiated solution at pH 6.5. A G(-activity) = 0.12 +- 0.01 was found. At the same time no corresponding loss in free sulfhydryls was observed. These results confirmed the essentiality of methionine for the enzymatic activity as known from previous studies. Irradiation with the radical anions, (CNS)2- and Br2- generated in ?-irradiated solutions at pH 6.5, strongly inactivated isocitrate dehydrogenase with yields of G(-activity) of 2.1 and 3.9, respectively. Part of the inactivating effect, however, is due to oxidation of sulfhydryl groups. These results lead to the conclusion that tryptophan is an essential amino-acid residue to isocitrate dehydrogenase from A. vinelandii. The presence of tryptophan in the enzyme was demonstrated by pulse radiolysis

  16. Antioxidant activity and free radical scavenging capacity of phenolic extracts from Helicteres isora L. and Ceiba pentandra L.

    Science.gov (United States)

    Loganayaki, Nataraj; Siddhuraju, Perumal; Manian, Sellamuthu

    2013-08-01

    In the present study, antioxidant activities of the phenolic extracts from H. isora fruits and C. pentandra seeds were investigated by employing established in vitro systems, which included reducing power, OH(?), DPPH(?), ABTS(?+), linoleic acid emulsion, metal chelation and antihemolytic activity. The extracts of C. pentandra contained relatively higher levels of total phenolics and flavonoids than those of H. isora. All the extracts showed dose dependent reducing power activity and moreover, they were well correlated with the total phenolic substances. A similar dose dependant trend has also been observed for hydroxyl radical scavenging activity and DPPH(?) radical scavenging activity. Further, addition of 250 ?g of extracts to the reaction mixture produced 41.3-54.6% peroxidation inhibiting activity during 60 h of incubation. The potential of multiple antioxidant activity of samples can be further evidenced by inhibition of reactive oxygen mediated erythrocyte cell lysis and metal ion chelating activity. PMID:24425970

  17. Spectroscopic studies on the antioxidant activity of ellagic acid

    Science.gov (United States)

    Kilic, Ismail; Ye?ilo?lu, Ye?im; Bayrak, Yüksel

    2014-09-01

    Ellagic acid (EA, C14H6O8) is a natural dietary polyphenol whose benefits in a variety of diseases shown in epidemiological and experimental studies involve anti-inflammation, anti-proliferation, anti-angiogenesis, anticarcinogenesis and anti-oxidation properties. In vitro radical scavenging and antioxidant capacity of EA were clarified using different analytical methodologies such as total antioxidant activity determination by ferric thiocyanate, hydrogen peroxide scavenging, 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2?-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity and superoxide anion radical scavenging, ferrous ions (Fe2+) chelating activity and ferric ions (Fe3+) reducing ability. EA inhibited 71.2% lipid peroxidation of a linoleic acid emulsion at 45 ?g/mL concentration. On the other hand, butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), ?-tocopherol and ascorbic acid displayed 69.8%, 66.8%, 64.5% and 59.7% inhibition on the peroxidation of linoleic acid emulsion at the same concentration, respectively. In addition, EA had an effective DPPH• scavenging, ABTSrad + scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, ferric ions (Fe3+) reducing power and ferrous ions (Fe2+) chelating activities. Also, those various antioxidant activities were compared to BHA, BHT, ?-tocopherol and ascorbic acid as references antioxidant compounds. These results suggested that EA can be used in the pharmacological, food industry and medicine because of these properties.

  18. Characterization of the peroxidase mechanism upon reaction of prostacyclin synthase with peracetic acid. Identification of a tyrosyl radical intermediate.

    Science.gov (United States)

    Yeh, Hui-Chun; Gerfen, Gary J; Wang, Jinn-Shyan; Tsai, Ah-Lim; Wang, Lee-Ho

    2009-02-10

    Prostacyclin synthase (PGIS) is a membrane-bound class III cytochrome P450 that catalyzes an isomerization of prostaglandin H(2), an endoperoxide, to prostacyclin. We report here the characterization of the PGIS intermediates in reactions with other peroxides, peracetic acid (PA), and iodosylbenzene. Rapid-scan stopped-flow experiments revealed an intermediate with an absorption spectrum similar to that of compound ES (Cpd ES), which is an oxo-ferryl (Fe(IV)O) plus a protein-derived radical. Cpd ES, formed upon reaction with PA, has an X-band (9 GHz) EPR signal of g = 2.0047 and a half-saturation power, P(1/2), of 0.73 mW. High-field (130 GHz) EPR reveals the presence of two species of tyrosyl radicals in Cpd ES with their g-tensor components (g(x), g(y), g(z)) of 2.00970, 2.00433, 2.00211 and 2.00700, 2.00433, 2.00211 at a 1:2 ratio, indicating that one is involved in hydrogen bonding and the other is not. The line width of the g = 2 signal becomes narrower, while its P(1/2) value becomes smaller as the reaction proceeds, indicating migration of the unpaired electron to an alternative site. The rate of electron migration ( approximately 0.2 s(-1)) is similar to that of heme bleaching, suggesting the migration is associated with the enzymatic inactivation. Moreover, a g = 6 signal that is presumably a high-spin ferric species emerges after the appearance of the amino acid radical and subsequently decays at a rate comparable to that of enzymatic inactivation. This loss of the g = 6 species thus likely indicates another pathway leading to enzymatic inactivation. The inactivation, however, was prevented by the exogenous reductant guaiacol. The studies of PGIS with PA described herein provide a mechanistic model of a peroxidase reaction catalyzed by the class III cytochromes P450. PMID:19187034

  19. Formulation design and evaluation of amorphous ABT-102 nanoparticles.

    Science.gov (United States)

    Jog, Rajan; Kumar, Sumit; Shen, Jie; Jugade, Nital; Tan, David Cheng Thiam; Gokhale, Rajeev; Burgess, Diane J

    2016-02-10

    Amorphous nanoparticles are able to enhance the kinetic solubility and concomitant dissolution rates of BCS class II and BCS class II/IV molecules due to their characteristic increased supersaturation levels, smaller particle size and greater surface area. A DoE approach was applied to investigate formulation and spray drying process parameters for the preparation of spray dried amorphous ABT-102 nanoparticles. Stability studies were performed on the optimized formulations to monitor physical and chemical changes under different temperature and humidity conditions. SLS/soluplus(®) and SLS/PVP K25 were the best stabilizer combinations. Trehalose was used to prevent nanoparticle aggregation during spray drying. Particle size distribution, moisture content, PXRD, PLM, FTIR and in vitro dissolution were utilized to characterize the spray dried nanoparticle formulations. The formulations prepared using soluplus(®) showed enhanced dissolution rate compared to those prepared using PVP K25. Following three months storage, it was observed that the formulations stored at 4°C were stable in terms of particle size distribution, moisture content, and crystallinity, whereas those stored at 25°C/60%RH and 40°C/75%RH were unstable. A predictive model to prepare stable solid spray dried amorphous ABT-102 nanoparticles, incorporating both formulation and process parameters, was successfully developed using multiple linear regression analysis. PMID:26705150

  20. Prostatic Fatty Acids and Cancer Recurrence Following Radical Prostatectomy for Early-Stage Prostate Cancer

    Science.gov (United States)

    Objective: Results from some observational studies suggest that diet and energy balance influence the clinical course of early-stage prostate cancer. To evaluate possible mechanisms, we prospectively examined the relation between prostatic concentrations of fatty acids at diagnosis and cancer recurr...

  1. Low-weight Molecular Organic Peroxides, Acids and Carbonyls Production in the Gas-phase OH radical-initiated Reaction of Alpha-pinene at Different Relative Humidity

    Science.gov (United States)

    Li, H.; Huang, D.; Huang, L.; Chen, Z.

    2014-12-01

    The photooxidation of biogenic volatile organic compounds (BVOCs) plays an important role in the chemistry of atmosphere. Although alpha-pinene is the most widely observed monoterpene among BVOCs, its photooxidation mechanism is still incompletely understood. In this study, we has investigated the OH radical-initiated reaction of alpha-pinene in the gas phase using a flow tube reactor at different relative humidity, focusing on the low-weight molecular products, including carbonyls, carboxylic acids and organic peroxides. The results show the relationship between these products and water vapor concentrations and indicate that the water vapor may affect the reactions of RO2 radicals. Interestingly, we find the formation of peroxy carboxylic acids in this reaction for the first time. Our findings provide a useful insight into the role of water vapor in the reaction of alpha-pinene with OH radicals.

  2. AVALIAÇÃO DO RADICAL N,N-DIETIL-1,4-FENILENODIAMINO (DEPD•+ COMO SONDA ESPECTROFOTOMÉTRICA PARA DETERMINAÇÃO DA CAPACIDADE ANTIOXIDANTE EM BEBIDAS

    Directory of Open Access Journals (Sweden)

    Rosicleide Viturina dos Santos

    2015-08-01

    Full Text Available AbstractMany well-established methods for determining the antioxidant capacities in several samples have been described in literature. However, DPPH (2,2-diphenyl-1-picrylhydrazyl and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid are the main two methods that utilize radicals as spectrophotometric probes for analysis. Nevertheless, these methods have certain limitations because of their slower kinetics, solvent polarity effects, the hydrophilicity and lipophilicity of the compounds, chemical costs, etc. In this study, a spectrophotometric method for determining the antioxidant capacity in beverages was developed based on an exploration of the cation radical derived from DEPD. This method was based on the oxidation of aromatic amines with Fe(III ions at pH 4.0, which leads to their corresponding purple cation radicals (DEPD•+ with λmax values at 500 and 540 nm. The addition of an antioxidant after the formation of the radical leads to a reduction in color intensity that is proportional to the antioxidant concentration in the medium. Results obtained using this method were compared with the Folin-Ciocalteau, ABTS and DPPH methods in terms of applications in wines, teas, and infusions samples. Linear correlation analysis at a 95% confidence level was employed to compare the results, which were in good agreement with a correlation coefficient of r > 0.9000. Thus, the developed method was simple, accurate, and consistent with other assays for the determination of the total amount of phenolic compounds and antioxidant capacity.

  3. Isolation of Lactic Acid Bacteria Showing Antioxidative and Probiotic Activities from Kimchi and Infant Feces.

    Science.gov (United States)

    Ji, Keunho; Jang, Na Young; Kim, Young Tae

    2015-09-28

    The purpose of this study was to investigate lactic acid bacteria with antioxidative and probiotic activities isolated from Korean healthy infant feces and kimchi. Isolates A1, A2, S1, S2, and S3 were assigned to Lactobacillus sp. and isolates A3, A4, E1, E2, E3, and E4 were assigned to Leuconostoc sp. on the basis of their physiological properties and 16S ribosomal DNA sequence analysis. Most strains were confirmed as safe bioresources through nonhemolytic activities and non-production of harmful enzymes such as ?-glucosidase, ?- glucuronidase and tryptophanase. The 11 isolates showed different resistance to acid and bile acids. In addition, they exhibited antibacterial activity against foodborne bacteria, especially Bacillus cereus, Listeria monocytogenes, and Escherichia coli. Furthermore, all strains showed significantly high levels of hydrophobicity. The antioxidant effects of culture filtrates of the 11 strains included 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging capacity, 2.2'- azino-bis (2-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical cation scavenging activity, and superoxide dismutase activity. The results revealed that most of the culture filtrates have effective scavenging activity for DPPH and ABTS radicals. All strains appeared to have effective superoxide dismutase activity. In conclusion, the isolated strains A1, A3, S1, and S3 have significant probiotic activities applicable to the development of functional foods and health-related products. These strains might also contribute to preventing and controlling several diseases associated with oxidative stress, when used as probiotics. PMID:25951843

  4. DEGRADATION OF ACRYLIC ACID-GRAFTED CELLULOSE IN AQUEOUS MEDIUM WITH RADICAL INITIATORS

    OpenAIRE

    AÍDA NEIRA; MIGUEL TARRAGA; ROSA CATALAN

    2008-01-01

    The chemical modification of cellulose by grafting reaction with Acrylic Acid (AA) considering different reaction factors was investigated. Natural polymers such as Santa Fe Cellulose, Microcrystalline Cellulose (Avicell) and Secondary Pulp were studied as substrates. pH effect; Ce (IV), Mn(VII) and Fenton as initiators; time and temperature polymerization were investigated. Grafting reachs a maximum, 90 % graft, at pH 7. A medium to weak C=0 band at 1715 cm"¹ for carboxylic group in FTIR spe...

  5. About formation of radicals by the photolysis of uranyl salts in aliphatic carbon acids

    International Nuclear Information System (INIS)

    The photolysis of UO2(NO3)2x6H2O and UO2(RCOO)2 (R=CH3, C2H5, C3H7, and CH(CH3)2) has been studied by ESR spin trapping technique using nitrosodurene as a spin trap. Evidences for electron transfer from both coordinated anions and carboxylic acid to U(VI) were found. (author)

  6. Effect of free-radical spin trap N-tert-butyl-alpha-phenylnitrone on seizures induced in immature rats by homocysteic acid.

    Czech Academy of Sciences Publication Activity Database

    Folbergrová, Jaroslava; Druga, Rastislav; Otáhal, Jakub; Haugvicová, Renata; Mareš, Pavel; Kubová, Hana

    2005-01-01

    Ro?. 46, ?. S6 (2005), s. 375-375. ISSN 0013-9580. [International Epilepsy Congress /26./. 28.08.2005-01.09.2005, Paris] R&D Projects: GA ?R(CZ) GA309/02/1238; GA ?R(CZ) GA309/05/2015 Keywords : free radical scavenger * epilepsy * immature rats * homocysteic acid Subject RIV: ED - Physiology

  7. The ratio of oleic-to-stearic acid in the prostate predicts biochemical failure after radical prostatectomy for localized prostate cancer

    Science.gov (United States)

    Our study examined lifestyle-related factors that may influence the prognosis of clinically localized prostate cancer, we evaluated the relative impact of obesity and prostatic fatty acid concentrations at diagnosis on risk of biochemical failure following radical prostatectomy. Height and weight w...

  8. Antioxidant Activity and Mechanism of Protocatechuic Acid in vitro

    Directory of Open Access Journals (Sweden)

    Shuzhi Chen

    2011-07-01

    Full Text Available Background: Protocatechuic acid (PCA is a natural phenolic acid widely distributed in plantsand is considered as an active component of some traditional Chinese herbal medicines such as Cibotium barometz (L. J.Sm, Stenoloma chusanum (L. Ching, Ilex chinensis Sims. PCA was reported to possess various pharmacological effects which may be closely correlated with its antioxidant activities. However, the antioxidant of PCA has not been investigatedsystematically yet. Methods: In the study, the antioxidant activities of protocatechuic acid were measured in vitrousing various antioxidant assays including 1,1-diphenyl-2-picryl-hydrazyl (DPPH•, 2,2’-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid (ABTS+•, superoxide anion radicals (•O2- and hydroxyl radical (•OH scavenging activity, ferric ions (Fe3+ and cupric ions (Cu2+ reducing power, ferrous ions (Fe2+ and cupric ions (Cu2+ chelating activity, compared with the positive controls Trolox or BHT.Results: In all assays, PCA along with positive controls exhibited dose-dependently antioxidant ability. Comparing to a standard antioxidant Trolox, the relative antioxidant activity of PCA (i.e. the ratio of IC50(Trolox/IC50(PCA was calculated as 2.8, 2.3, 3.7, 6.1, 4.2, 1.0, 2.7, 1.5, respectively, for DPPH, ABTS, reducing power (Fe3+, reducing power (Cu2+, superoxide anion radical-scavenging, hydroxyl radical-scavenging, chelating ability (Fe2+ and chelating ability (Cu2+. Functional Foods in Health and Disease 2011; 7:232-244 Conclusion: Comparing to Trolox, PCA shows much more effective antioxidant activity in vitro in both lipid and aqueous media. Hence, it could therefore be used in pharmacological or food industry as a natural antioxidant. It may exhibit antioxidant activity by both chelating metal transition ions as well as by scavenging free radicals via donating hydrogen atom (H• or electron (e.

  9. First-principles study of radiation-induced radicals in solid-state amino acids and sugars: confrontation of density-functional calculations with experimental results

    OpenAIRE

    Pauwels, Ewald

    2004-01-01

    In this work, we present an extensive computational study of several radiationinduced radicals of biomolecules. In particular, two specific types of molecular systems will be highlighted: amino acids and sugars. Both systems are abundantly present in the natural world and are vital to the existence of life in all its forms. Amino acids are the building blocks of polypeptides and proteins, which are involved in nearly all biochemical processes. Sugars (or carbohydrates) also play a key role, n...

  10. Rate constants for the reactions of halogenated organic radicals

    International Nuclear Information System (INIS)

    Absolute rate constants have been measured by means of pulse radiolysis for the reactions of various halogenated aliphatic compounds (ethane derivatives, including the anaesthetics halothane, enflurane, isoflurane and methoxyflurane) with hydrated electrons and OH anion radicals, the reactions of halogenated carbon-centred radicals, derived thereby, with molecular oxygen, and the reactions of halogenated peroxyl radicals with various antioxidants (ascorbate, chlorpromazine promethazine, propyl gallate, ABTS) in aqueous solutions. All oxygen addition reactions occur essentially diffusion-controlled. This finding is correlated with the stereoelectronic properties of the primary carbon-centred radicals. The oxidative power of the halogenated peroxyl radicals reflects the inductive-l effect of the halogens and accordingly increases with the degree of halogen substitution, with fluorine substituents being particularly effective. The peroxyl radicals derived from freon 113, namely CClF2CClFOO radical and CCl2FCF2OO radical, have been identified as the best oxidants among these species. (author)

  11. The structure and properties of free radicals: An electron spin resonance study of radiation damage to nucleic acid and protein components and to some sulfur-substituted derivitives

    International Nuclear Information System (INIS)

    When cellular systems are exposed to ionizing radiation the long-term effects may range from minor disturbances to such dramatic changes as mutations and cell death. The processes leading to these macroscopical injuries are primarily confined at the molecular level. In all models aimed at a description of the action of radiation at the molecular level the formation of free radicals (which are species containing unpaired electrons) is a central concept. The technique of ESR spectroscopy is uniquely suited to study free radicals, as it is based on resonance absorption of energy by unpaired electrons in a magnetic field. ESR spectroscopy makes it possible to detect free radicals and, in some cases, to identify them. In order to study free radicals by ESR it is necessary to build up a sufficient number of unpaired spins in the sample (approximately 1011 or more, depending on the shape of the resonance). This may be different techniques have been used to trap the induced radicals or to attain a sufficient steady state concentration level. A procedure which seems to contain a large amount of information is to irradiate at low temperatures, and, by subsequent heat-treatment of the sample to study the reactions and fate of the induced radicals. In this thesis single crystal studies of aromatic amino acids and pyrimidine derivitives together with some substituted purine derivitives are presented, and the results are discussed in relation to the present knowledge about radical formation in these classes of compounds. Single crystal studies of some sulfur-containing aromatic compounds have been presented with the purpose of shedding light on the electronic structure of sulfur-centred radicals. (JIW)

  12. Factors Influencing the ABT Phenomenon among Graduate Students in a Master Program in Mexico

    Science.gov (United States)

    Gonzalez-Castillo, Vicente; Cisneros-Cohernour, Edith J.

    2007-01-01

    This paper presents the findings of a study examining the factors that influence the ABT phenomenon (all but thesis) among graduate students of a Master in Education program in the Southeast of Mexico. Findings of the study identified individual and organizational factors influencing ABT. The study allowed for a better understanding about how…

  13. DEGRADATION OF ACRYLIC ACID-GRAFTED CELLULOSE IN AQUEOUS MEDIUM WITH RADICAL INITIATORS

    Directory of Open Access Journals (Sweden)

    AÍDA NEIRA

    2008-03-01

    Full Text Available The chemical modification of cellulose by grafting reaction with Acrylic Acid (AA considering different reaction factors was investigated. Natural polymers such as Santa Fe Cellulose, Microcrystalline Cellulose (Avicell and Secondary Pulp were studied as substrates. pH effect; Ce (IV, Mn(VII and Fenton as initiators; time and temperature polymerization were investigated. Grafting reachs a maximum, 90 % graft, at pH 7. A medium to weak C=0 band at 1715 cm"¹ for carboxylic group in FTIR spectroscopy is presented. Santa Fe and Avicel cellulose grafted whith AA at 17 hours are degraded. Secondary pulp with Fenton at 50-60 and 70 °C at 17 hours are degraded too. The degradation of polymers at long reaction times at 17 hours and 70°C were analized by FTIR spectroscopy and electronic microscopy analysis (SEM.

  14. DEGRADATION OF ACRYLIC ACID-GRAFTED CELLULOSE IN AQUEOUS MEDIUM WITH RADICAL INITIATORS

    Scientific Electronic Library Online (English)

    AÍDA, NEIRA; MIGUEL, TARRAGA; ROSA, CATALAN.

    2008-03-01

    Full Text Available The chemical modification of cellulose by grafting reaction with Acrylic Acid (AA) considering different reaction factors was investigated. Natural polymers such as Santa Fe Cellulose, Microcrystalline Cellulose (Avicell) and Secondary Pulp were studied as substrates. pH effect; Ce (IV), Mn(VII) and [...] Fenton as initiators; time and temperature polymerization were investigated. Grafting reachs a maximum, 90 % graft, at pH 7. A medium to weak C=0 band at 1715 cm"¹ for carboxylic group in FTIR spectroscopy is presented. Santa Fe and Avicel cellulose grafted whith AA at 17 hours are degraded. Secondary pulp with Fenton at 50-60 and 70 °C at 17 hours are degraded too. The degradation of polymers at long reaction times at 17 hours and 70°C were analized by FTIR spectroscopy and electronic microscopy analysis (SEM).

  15. Free radical derivatives formed from cyclooxygenase-catalyzed dihomo-?-linolenic acid peroxidation can attenuate colon cancer cell growth and enhance 5-fluorouracil?s cytotoxicity

    Directory of Open Access Journals (Sweden)

    Yi Xu

    2014-01-01

    Full Text Available Dihomo-?-linolenic acid (DGLA and its downstream fatty acid arachidonic acid (AA are both nutritionally important ?–6 polyunsaturated fatty acids (?–6s. Evidence shows that, via COX-mediated peroxidation, DGLA and its metabolites (1-series prostaglandins are associated with anti-tumor activity, while AA and its metabolites (2-series prostaglandins could be tightly implicated in various cancer diseases. However, it still remains a mystery why DGLA and AA possess contrasting bioactivities. Our previous studies showed that DGLA could go through an exclusive C-8 oxygenation pathway during COX-catalyzed lipid peroxidation in addition to a C-15 oxygenation pathway shared by both DGLA and AA, and that the exclusive C-8 oxygenation could lead to the production of distinct DGLA?s free radical derivatives that may be correlated with DGLA?s anti-proliferation activity. In the present work, we further investigate the anti-cancer effect of DGLA?s free radical derivatives and their associated molecular mechanisms. Our study shows that the exclusive DGLA?s free radical derivatives from C-8 oxygenation lead to cell growth inhibition, cell cycle arrest and apoptosis in the human colon cancer cell line HCA-7 colony 29, probably by up-regulating the cancer suppressor p53 and the cell cycle inhibitor p27. In addition, these exclusive radical derivatives were also able to enhance the efficacy of 5-Fluorouracil (5-FU, a widely used chemo-drug for colon cancer. For the first time, we show how DGLA?s radical pathway and metabolites are associated with DGLA?s anti-cancer activities and able to sensitize colon cancer cells to chemo-drugs such as 5-FU. Our findings could be used to guide future development of a combined chemotherapy and dietary care strategy for colon cancer treatment.

  16. Melt Free-Radical Grafting of Maleic Anhydride onto Biodegradable Poly(lactic acid by Using Styrene as A Comonomer

    Directory of Open Access Journals (Sweden)

    Piming Ma

    2014-05-01

    Full Text Available Maleic anhydride (MA was grafted onto poly(lactic acid (PLA in the presence of styrene (St by using a free-radical grafting methodology. The grafting degree (Dg of MA was increased from 0.65 wt % to 1.1 wt % with the St/MA ratio up to 2/1, where the grafting efficiency (Eg of MA was 27%. However, both Dg and Eg were decreased with further increasing of the St/MA ratio to 4/1. The Dg of MA increased with MA concentration and showed a maximum at 180 °C in the temperature range of 165 °C–190 °C. The grafting mechanisms of MA in the presence of St are analyzed based on titration, thermogravimetric analysis and infrared results, i.e., MA is grafted onto PLA chains via single monomers and a charge-transfer-complex (CTC at St/MA ratios of ? 1/1, while dominantly via St-co-MA oligomers at St/MA ratios of around 2/1. Copolymerization rather than grafting of St and MA occurs at St/MA ratios of around 4/1. The thermal stability of PLA was compromised to a certain extent by the grafting of MA, resulting in reductions in the decomposition temperature (Td-5% and molecular weight of the PLA. In addition, the crystallization and melting temperatures of the PLA were slightly reduced after the grafting.

  17. Phytochemical Analysis and Free Radical Scavenging Activity of Medicinal Plants Gnidia glauca and Dioscorea bulbifera

    OpenAIRE

    Ghosh, Sougata; Derle, Abhishek; Ahire, Mehul; More, Piyush; Jagtap, Soham; Phadatare, Suvarna D.; Patil, Ajay B.; Jabgunde, Amit M; Sharma, Geeta K.; Shinde, Vaishali S.; Pardesi, Karishma; Dhavale, Dilip D.; Balu A. Chopade

    2013-01-01

    Gnidia glauca and Dioscorea bulbifera are traditional medicinal plants that can be considered as sources of natural antioxidants. Herein we report the phytochemical analysis and free radical scavenging activity of their sequential extracts. Phenolic and flavonoid content were determined. Scavenging activity was checked against pulse radiolysis generated ABTS•+ and OH radical, in addition to DPPH, superoxide and hydroxyl radicals by biochemical methods followed by principal component analysis....

  18. Radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl of ascorbic acid 2-glucoside (AA-2G) and 6-acyl-AA-2G.

    Science.gov (United States)

    Fujinami, Y; Tai, A; Yamamoto, I

    2001-05-01

    The radical scavenging activity of the stable derivatives, which are O-substituted at the C-2 position of ascorbic acid (AA), against 1,1-diphenyl-2-picrylhydrazyl (DPPH) was evaluated in buffer under different pH conditions, and compared with those of AA and alpha-tocopherol. AA was shown to have 50% radical scavenging ability (EC50) at a concentration of 2.2 x 10(-5) M against 0.1 mM DPPH in 60% ethanol. Ascorbyl 6-palmitate, a lipophilic AA derivative which has a free endiol group and is therefore unstable, also showed potent radical scavenging activity with EC50 of 2.9 x 10(-5) M. A typical lipophilic antioxidant, alpha-tocopherol gave a similar EC50 value as that of AA. In contrast, ascorbyl 2,6-dipalmitate, AA 2-phosphate and AA 2-sulfate exhibited negligible scavenging activity. On the other hand, 2-O-alpha-D-glucopyranosyl-L-ascorbic acid (AA-2G) and a series of 6-O-acyl-2-O-alpha-D-glucopyranosyl-L-ascorbic acids (6-Acyl-AA-2G) themselves exhibited the radical scavenging activity of EC50: 6.1 x 10(-5) M and 4.4 x 10(-5)-5.9 x 10(-5) M, respectively, although their activities were lower than that of AA. Among 6-Acyl-AA-2G derivatives, the EC50 values tended to decrease with increasing length of their acyl carbon group. Increasing pH of the buffer resulted in decrease in the scavenging activity of all compounds tested as expected. We speculate that the difference in the radical scavenging activity of derivatives O-substituted at the C-2 position of AA may be ascribed to the linkage type of the substituent group to the endiol-lactone resonance system and the degree of dissociation of the C-3 proton. PMID:11383624

  19. Modeling nitrous acid and its impact on ozone and hydroxyl radical during the Texas Air Quality Study 2006

    Directory of Open Access Journals (Sweden)

    B. H. Czader

    2012-02-01

    Full Text Available Nitrous acid (HONO mixing ratios for the Houston metropolitan area were simulated with the Community Multiscale Air Quality (CMAQ model for an episode during the Texas Air Quality Study (TexAQS II in August/September 2006 and compared to in-situ MC/IC (mist-chamber/ion chromatograph and long path DOAS (Differential Optical Absorption Spectroscopy measurements at three different altitudes. Several HONO sources were accounted for in simulations, such as gas phase formation, direct emissions, nitrogen dioxide (NO2* hydrolysis, photo-induced formation from excited NO2* and photo-induced conversion of NO2 into HONO on surfaces covered with organic materials. Compared to the gas-phase HONO formation there was about a tenfold increase in HONO mixing ratios when additional HONO sources were taken into account, which improved the correlation between modeled and measured values. Concentrations of HONO simulated with only gas phase chemistry did not change with altitude, while measured HONO concentrations decrease with height. A trend of decreasing HONO concentration with altitude was well captured with CMAQ predicted concentrations when heterogeneous chemistry and photolytic sources of HONO were taken into account. Heterogeneous HONO production mainly accelerated morning ozone formation, albeit slightly. Also HONO formation from excited NO2 only slightly affected HONO and ozone (O3 concentrations. Photo-induced conversion of NO2 into HONO on surfaces covered with organic materials turned out to be a strong source of daytime HONO. Since HONO immediately photo-dissociates during daytime its ambient mixing ratios were only marginally altered (up to 0.5 ppbv, but significant increase in the hydroxyl radical (OH and ozone concentration was obtained. In contrast to heterogeneous HONO formation that mainly accelerated morning ozone formation, inclusion of photo-induced surface chemistry influenced ozone throughout the day.

  20. Modeling nitrous acid and its impact on ozone and hydroxyl radical during the Texas Air Quality Study 2006

    Directory of Open Access Journals (Sweden)

    B. H. Czader

    2012-08-01

    Full Text Available Nitrous acid (HONO mixing ratios for the Houston metropolitan area were simulated with the Community Multiscale Air Quality (CMAQ Model for an episode during the Texas Air Quality Study (TexAQS II in August/September 2006 and compared to in-situ MC/IC (mist-chamber/ion chromatograph and long path DOAS (Differential Optical Absorption Spectroscopy measurements at three different altitude ranges. Several HONO sources were accounted for in simulations, such as gas phase formation, direct emissions, nitrogen dioxide (NO2 hydrolysis, photo-induced formation from excited NO2 and photo-induced conversion of NO2 into HONO on surfaces covered with organic materials. Compared to the gas-phase HONO formation there was about a tenfold increase in HONO mixing ratios when additional HONO sources were taken into account, which improved the correlation between modeled and measured values. Concentrations of HONO simulated with only gas phase chemistry did not change with altitude, while measured HONO concentrations decrease with height. A trend of decreasing HONO concentration with altitude was well captured with CMAQ predicted concentrations when heterogeneous chemistry and photolytic sources of HONO were taken into account. Heterogeneous HONO production mainly accelerated morning ozone formation, albeit slightly. Also HONO formation from excited NO2 only slightly affected HONO and ozone (O3 concentrations. Photo-induced conversion of NO2 into HONO on surfaces covered with organic materials turned out to be a strong source of daytime HONO. Since HONO immediately photo-dissociates during daytime its ambient mixing ratios were only marginally altered (up to 0.5 ppbv, but significant increase in the hydroxyl radical (OH and ozone concentration was obtained. In contrast to heterogeneous HONO formation that mainly accelerated morning ozone formation, inclusion of photo-induced surface chemistry influenced ozone throughout the day.

  1. Histone H1- and other protein- and amino acid-hydroperoxides can give rise to free radicals which oxidize DNA

    DEFF Research Database (Denmark)

    Luxford, C; Morin, B; Dean, R T; Davies, Michael Jonathan

    carbon-centred radicals (detected by electron paramagnetic resonance spectroscopy) on exposure to Cu(+) and other transition metal ions. These hydroperoxide-derived radicals react readily with pyrimidine DNA bases and nucleosides to give adduct species (i.e. protein-DNA base cross-links). Product....../ml). Evidence has also been obtained with DNA for reaction at cytosine and thymine, but not adenine; the lack of damage to the latter may result from damage transfer to 2'-deoxyguanosine residues. These studies demonstrate that initial radical-induced damage to nuclear proteins can give rise to subsequent DNA...

  2. Extremely enhanced contaminant decomposition catalyzed by hemin via the coupling of persistent free radicals and ascorbic acid.

    Science.gov (United States)

    Yao, Yuyuan; Jiang, Bin; Mao, Yajun; Chen, Juan; Huang, Zhenfu; Huang, Sanqing; Zhang, Li

    2015-10-27

    Persistent free radicals (PFRs) have mainly been reported as negative species. Here we report a positive role of PFRs in enhancing reactive oxygen species (ROS) generation for an extreme rate enhancement in environmental pollutant decomposition. PMID:26393410

  3. Radical-generating coordination complexes as tools for rapid and effective fragmentation and fluorescent labeling of nucleic acids for microchip hybridization.

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, J. J.; Chernov, B. K.; Tovstanovsky, I.; Mirzabekov, A. D.; Bavykin, S. G.; Biochip Technology Center; Northwestern Univ.; Engelhardt Inst. of Molecular Biology

    2002-12-15

    DNA microchip technology is a rapid, high-throughput method for nucleic acid hybridization reactions. This technology requires random fragmentation and fluorescent labeling of target nucleic acids prior to hybridization. Radical-generating coordination complexes, such as 1,10-phenanthroline-Cu(II) (OP-Cu) and Fe(II)-EDTA (Fe-EDTA), have been commonly used as sequence nonspecific 'chemical nucleases' to introduce single-strand breaks in nucleic acids. Here we describe a new method based on these radical-generating complexes for random fragmentation and labeling of both single- and double-stranded forms of RNA and DNA. Nucleic acids labeled with the OP-Cu and the Fe-EDTA protocols revealed high hybridization specificity in hybridization with DNA microchips containing oligonucleotide probes selected for identification of 16S rRNA sequences of the Bacillus group microorganisms.We also demonstrated cDNA- and cRNA-labeling and fragmentation with this method. Both the OP-Cu and Fe-EDTA fragmentation and labeling procedures are quick and inexpensive compared to other commonly used methods. A column-based version of the described method does not require centrifugation and therefore is promising for the automation of sample preparations in DNA microchip technology as well as in other nucleic acid hybridization studies.

  4. Norcantharidin enhances ABT-263-mediated anticancer activity in neuroblastoma cells by upregulation of Noxa.

    Science.gov (United States)

    Wang, Xiaohui; Gu, Zhimin; Li, Gongquan; Zhang, Shufeng; Cao, Zhenjie; Yang, Zhanfeng; Liu, Guangzhi

    2014-08-01

    Neuroblastoma is an aggressive childhood disease. Even with intensive conventional treatments, the long term survival rate for children with neuroblastoma remains less than 40%, highlighting the importance of finding new therapies. Bcl-2 family proteins play crucial roles in survival, proliferation and chemotherapeutic resistance of neuroblastoma cells. Therefore, targeting Bcl-2 with small molecule inhibitor ABT-263 could be a novel strategy for treatment of neuroblastoma. However, previous studies indicated that most neuroblastoma cell lines are resistant to ABT-263-mediated apoptosis. Thus, it is crucial to discover approaches that could overcome ABT-263 resistance. In this study, we examined the anticancer activity of ABT-263 in combination with norcantharidin (NCTD), a small-molecule anticancer drug derived from a traditional Chinese medicine, in human malignant neuroblastoma cells. We found that NCTD substantially enhanced ABT-263-mediated apoptosis induction, cell viability inhibition, and clonal formation inhibition in neuroblastoma SH-SY5Y and CHLA-119 cell lines. Moreover, the combination anticancer activity was accompanied by upregulation of Noxa, and was associated with characteristics of mitochondrial apoptosis signaling, such as cytosolic release of cytochrome c, activation of caspase-9,-3, and cleavage of PARP. Notably, we observed that knockdown of Noxa significantly attenuated cell death induction by cotreatment with ABT-263 and NCTD, indicating Noxa essentially contributes to the combination anticancer effect. Collectively, our study demonstrated that NCTD could overcome ABT-263-resistance in neuroblastoma cells, and suggested that combinational treatment of ABT-263 with NCTD might be a novel therapeutic option for children with neuroblastoma. PMID:24891300

  5. Free Radical Scavenging Activity and Reducing Capacity of Five Southern Thai Indigenous Vegetable Extracts

    Directory of Open Access Journals (Sweden)

    Worawan PANPIPAT

    2010-01-01

    Full Text Available The phenolic compounds of five southern Thai indigenous vegetables including Mon-pu (Glochidion wallichianum Muell Arg, Cha-plu (Piper sarmentosum Roxb., white popinac (Leucaena leucocephala de Wit., djenkol tree (Archidendrom jiringa I. C. Nielsen. and stink bean (Parkia speciosa Hassk. were extracted using different solvents (50 % acetone, 80 % methanol and distilled water at a ratio of sample to extracting medium of 1:25 (w/v. The extracts were analyzed for total phenolic content using the Folin-Ciocalteu procedure, free radical scavenging capacity by using 2’,2’-azinobis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS and 1,1-diphenyl-2-picrylhydrazyl (DPPH methods, and reducing capacity by using a ferric reducing antioxidant power (FRAP assay. The acetone extracts of all plants possessed the highest total phenolic content followed by the methanolic and distilled water extracts, respectively. The highest total phenolic content was found in the acetone extracts of Mon-pu and white popinac (p < 0.05. The acetone extracts of all plants showed higher free radical scavenging capacity and reducing capacity than those of their methanolic and water extracts counterparts, respectively (p < 0.05. Among all plants tested, the extracts of Mon-pu extracted with all extracting media exhibited the highest free radical scavenging and reducing abilities (p < 0.05. The present study suggested that the acetone extract of Mon-pu was a potential source of natural antioxidants.

  6. A non-acid-assisted and non-hydroxyl-radical-related catalytic ozonation with ceria supported copper oxide in efficient oxalate degradation in water

    KAUST Repository

    Zhang, Tao

    2012-06-01

    Oxalate is usually used as a refractory model compound that cannot be effectively removed by ozone and hydroxyl radical oxidation in water. In this study, we found that ceria supported CuO significantly improved oxalate degradation in reaction with ozone. The optimum CuO loading amount was 12%. The molar ratio of oxalate removed/ozone consumption reached 0.84. The catalytic ozonation was most effective in a neutral pH range (6.7-7.9) and became ineffective when the water solution was acidic or alkaline. Moreover, bicarbonate, a ubiquitous hydroxyl radical scavenger in natural waters, significantly improved the catalytic degradation of oxalate. Therefore, the degradation relies on neither hydroxyl radical oxidation nor acid assistance, two pathways usually proposed for catalytic ozonation. These special characters of the catalyst make it suitable to be potentially used for practical degradation of refractory hydrophilic organic matter and compounds in water and wastewater. With in situ characterization, the new surface Cu(II) formed from ozone oxidation of the trace Cu(I) of the catalyst was found to be an active site in coordination with oxalate forming multi-dentate surface complex. It is proposed that the complex can be further oxidized by molecular ozone and then decomposes through intra-molecular electron transfer. The ceria support enhanced the activity of the surface Cu(I)/Cu(II) in this process. © 2012 Elsevier B.V.

  7. Scavenger Activity Evaluation of the Clove Bud Essential Oil (Eugenia caryophyllus) and Eugenol Derivatives Employing ABTS Decolorization.

    Science.gov (United States)

    Merchán Arenas, Diego R; Acevedo, Amner Muñoz; Vargas Méndez, Leonor Y; Kouznetsov, Vladimir V

    2011-01-01

    The essential oil (EO) of clove bud dried fruits from Eugenia caryophyllus was obtained by a conventional hydrodistillation process in an excellent yield (11.7 %). Its chemical composition was analyzed by GC-MS, identifying eugenol as a main constituent (60.5%). Four eugenol-like molecules, ?-diisoeugenol, hydroxymethyleugenol, dihydroeugenol and 1,3-dioxanylphenol, were synthesized using eugenol or isoeugenol as initial precursors under green chemistry protocols. To evaluate the possible antioxidant capacity of eugenol compounds including the clove bud EO, the Trolox® Equivalent Antioxidant Capacity value, obtained by the ABTS(+•) radical-cation discoloration method, was employed. The methodology was performed in a UV-Vis reader of 96-well microplates (dilution methodology), using well-known antioxidant agents (BHA, BHT and vitamin E) as reference compounds. It was found that the prepared eugenol derivatives had a more potent free radical scavenger activity than the reference compounds. In particular, the most active molecules, ?-diisoeugenol and 1,3-dioxanylphenol, were ca. 3-fold more potent than vitamin E. PMID:22145105

  8. Protective effect of aqueous extract from Spirulina platensis against cell death induced by free radicals

    Directory of Open Access Journals (Sweden)

    Radhakrishnan Ammu

    2010-09-01

    Full Text Available Abstract Background Spirulina is a commercial alga well known to contain various antioxidants, especially phycocyanin. Apart from being sold as a nutraceutical, Spirulina is incorporated as a functional ingredient in food products and beverages. Most of the previous reports on antioxidant activity of Spirulina were based on chemical rather than cell-based assays. The primary objective of this study was to assess the antioxidant activity of aqueous extract from Spirulina based on its protective effect against cell death induced by free radicals. Methods The antioxidant activity of the cold water extract from food-grade Spirulina platensis was assessed using both chemical and cell-based assays. In the cell-based assay, mouse fibroblast cells (3T3 cells were incubated for 1 h in medium containing aqueous extract of Spirulina or vitamin C (positive control at 25, 125 and 250 ?g/mL before the addition of 50 ?M 1,1-diphenyl-2-picrylhydrazyl (DPPH or 3-ethylbenzothiazoline-6-sulfonic acid (ABTS. The cells were incubated for another 24 h before being assessed for cell death due to apoptosis using the Cell Death Detection ELISA Kit. Spectrophotometric assays based on DPPH and ABTS were also used to assess the antioxidant activity of the extract compared to vitamin C and vitamin E (positive controls. Results Spirulina extract did not cause cytotoxic effect on 3T3 cells within the range of concentrations tested (0 - 250 ?g/mL. The extract reduced significantly (p Conclusions The results showed that aqueous extract of Spirulina has a protective effect against apoptotic cell death due to free radicals. The potential application of incorporating Spirulina into food products and beverages to enhance their antioxidant capacity is worth exploring.

  9. In vitro alpha glucosidase inhibition and free-radical scavenging activity of propolis from Thai stingless bees in mangosteen orchard

    Directory of Open Access Journals (Sweden)

    Boonyadist Vongsak

    2015-10-01

    Full Text Available ABSTRACTThe chemical component and biological activity of propolis depend on flora area of bee collection and bee species. In the study, the propolis from three stingless bee species, Lepidotrigona ventralis Smith, Lepidotrigona terminata Smith, and Tetragonula pagdeni Schwarz, was collected in the same region of mangosteen garden from Thailand. Total phenolic content, alpha glucosidase inhibitory effect, and free-radical scavenging activity using FRAP, ABTS, DPPH assays were determined. The most potent activity of propolis extract was investigated for bioactive compounds and their quantity. The ethanol extract of T. pagdeni propolis had the highest total phenolic content 12.83 ± 0.72 g of gallic acid equivalents in 100 g of the extract, and the strongest alpha glucosidase inhibitory effect with the IC50 of 70.79 ± 6.44 µg/ml. The free-radical scavenging activity evaluated by FRAP, ABTS, DPPH assays showed the FRAP value of 279.70 ± 20.55 µmol FeSO4 equivalent/g extract and the IC50 of 59.52 ± 10.76 and 122.71 ± 11.76 µg/ml, respectively. Gamma- and alpha-mangostin from T. pagdeni propolis extract were isolated and determined for the biological activity. Gamma-mangostin exhibited the strongest activity for both alpha glucosidase inhibitory effect and free-radical scavenging activity. Using HPLC quantitative analysis method, the content of gamma- and alpha-mangostin in the extract was found to be 0.94 ± 0.01 and 2.77 ± 0.08% (w/w, respectively. These findings suggested that T. pagdeni propolis may be used as a more suitable raw material for nutraceutical and pharmaceutical products and these mangostin derivatives as markers.

  10. Application of Attenuated Total Reflectance-Fourier Transformed Infrared (ATR-FTIR) Spectroscopy To Determine the Chlorogenic Acid Isomer Profile and Antioxidant Capacity of Coffee Beans.

    Science.gov (United States)

    Liang, Ningjian; Lu, Xiaonan; Hu, Yaxi; Kitts, David D

    2016-01-27

    The chlorogenic acid isomer profile and antioxidant activity of both green and roasted coffee beans are reported herein using ATR-FTIR spectroscopy combined with chemometric analyses. High-performance liquid chromatography (HPLC) quantified different chlorogenic acid isomer contents for reference, whereas ORAC, ABTS, and DPPH were used to determine the antioxidant activity of the same coffee bean extracts. FTIR spectral data and reference data of 42 coffee bean samples were processed to build optimized PLSR models, and 18 samples were used for external validation of constructed PLSR models. In total, six PLSR models were constructed for six chlorogenic acid isomers to predict content, with three PLSR models constructed to forecast the free radical scavenging activities, obtained using different chemical assays. In conclusion, FTIR spectroscopy, coupled with PLSR, serves as a reliable, nondestructive, and rapid analytical method to quantify chlorogenic acids and to assess different free radical-scavenging capacities in coffee beans. PMID:26725502

  11. Effects of roasting temperature and duration on fatty acid composition, phenolic composition, Maillard reaction degree and antioxidant attribute of almond (Prunus dulcis) kernel.

    Science.gov (United States)

    Lin, Jau-Tien; Liu, Shih-Chun; Hu, Chao-Chin; Shyu, Yung-Shin; Hsu, Chia-Ying; Yang, Deng-Jye

    2016-01-01

    Roasting treatment increased levels of unsaturated fatty acids (linoleic, oleic and elaidic acids) as well as saturated fatty acids (palmitic and stearic acids) in almond (Prunus dulcis) kernel oils with temperature (150 or 180 °C) and duration (5, 10 or 20 min). Nonetheless, higher temperature (200 °C) and longer duration (10 or 20 min) roasting might result in breakdown of fatty acids especially for unsaturated fatty acids. Phenolic components (total phenols, flavonoids, condensed tannins and phenolic acids) of almond kernels substantially lost in the initial phase; afterward these components gradually increased with roasting temperature and duration. Similar results also observed for their antioxidant activities (scavenging DPPH and ABTS(+) radicals and ferric reducing power). The changes of phenolic acid and flavonoid compositions were also determined by HPLC. Maillard reaction products (estimated with non-enzymatic browning index) also increased with roasting temperature and duration; they might also contribute to enhancing the antioxidant attributes. PMID:26213005

  12. [Research on the Quantitative Analysis for In-Situ Detection of Acid Radical Ions Using Laser Raman Spectroscopy].

    Science.gov (United States)

    Chen, Jing; Li, Ying; Du, Zeng-feng; Gu, Yan-hong; Guo, Jin-jia

    2015-09-01

    Laser Raman spectroscopy as an in situ analytical technology can enable detailed investigation of the ocean environment. It is necessary to set up a quantitative analysis method based on laser Raman spectroscopy to understand the marine status in situ. In the laboratory investigations, varied concentration of HCO3(-), SO4(2-) and coastal waters of Qingdao are taken as the samples, operating 532 nm of laser, using fiber optic probes to simulate detection mode in situ. Raman spectra are analyzed using the method of internal standard normalization, multiple linear regression (MLR), general Partial Least Squares (PLS) and PLS based on dominant factor respectively in data processing. It was found that correlation coefficients of calibration curves are not high in internal standard normalization method and predicted relative errors on the prepared samples are much high, so internal standard normalization method cannot be effectively used in the quantitative analysis of HCO3(-), SO4(2-) in the water. And with the multiple linear regression, the analysis accuracy was improved effectively. The calibration curve of PLS based on dominant factor showed that the SO4(2-) and HCO3(-) of pre-made solution with correlation coefficient R2 of 0.990 and 0.916 respectively. The 30 mmol · L(-1) of SO4(2-) and 20 mmol · L(-1) of HCO3(-) in two target samples were determined with the relative errors lower than 3.262% and 5.267% respectively. SO4(2-) in the coastal waters as the research object was analyzed by above-mentioned methods, comparing with 28.01 mmol · L(-1) by ion chromatography. It was demonstrated that PLS based on dominant factor method is superior to the rest of the three analysis methods, which can be used in situ calibration, with the mean relative error about 1.128%. All the results show that analysis accuracy would be improved by the PLS based on dominant factor method to predict concentration of acid radical ions. PMID:26669165

  13. Pulse radiolytic study of electron transfer reaction for fast repair of the one-electron oxidized radicals of dAMP and dGMP by hydroxycinnamic acid derivatives

    International Nuclear Information System (INIS)

    Using the techniques of pulse radiolysis, it has been demonstrated that the interaction of one-electron-oxidized radicals of dAMP (2'-deoxyadenosine-5-monophosphate) and dGMP (2'-deoxyguanosine-5'-monophosphate), produced by SO·-4 radical reaction, with hydroxycinnamic acid derivatives proceeds via electron transfer reaction. The rate constants of electron transfer from hydroxycinnamic acid derivatives to oxidizing free radicals of dAMP and dGMP were obtained to be (1-3)x109 dm3 mol-1 s-1

  14. Free Radical Scavenging Profile and Myeloperoxidase Inhibition of Extracts from Antidiabetic Plants: Bauhinia forficata and Cissus sicyoides

    Scientific Electronic Library Online (English)

    NAJEH M, KHALIL; MARIA T, PEPATO; IGUATEMY L, BRUNETTI.

    Full Text Available There is abundant evidence that reactive oxygen species are implicated in several physiological and pathological processes. To protect biological targets from oxidative damage, antioxidants must react with radicáis and other reactive species faster than biological substrates do. The aim of the prese [...] nt study was to determine the in vitro antioxidant activity of aqueous extracts from leaves of Bauhinia forficata Link (Fabaceae - Caesalpinioideae) and Cissus sicyoides L. (Vitaceae) (two medicinal plants used popularly in the control of diabetes mellitus), using several different assay systems, namely, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) decolorization, superoxide anión radical (0(2)•-) scavenging and myeloperoxidase (MPO) activity. In the ABTS assay for total antioxidant activity, B. forficata showed IC50 = 8.00±0.07 ?g/mL, while C. sicyoides showed IC50 = 13.0±0.2 ?g/mL. However, the extract of C. sicyoides had a stronger effect on 0(2)•- (IC50 = 60.0±2.3 ?g/mL) than the extract of B. forficata (IC50 = 90.0±4.4 ?g/ mL). B. forficata also had a stronger inhibitory effect on MPO activity, as measured by guaiacol oxidation, than C. sicyoides. These results indicate that aqueous extracts of leaves of B. forficata and C. sicyoides are a potential source of natural antioxidants and may be helpful in the prevention of diabetic complications associated with oxidative stress.

  15. Free Radical Scavenging Profile and Myeloperoxidase Inhibition of Extracts from Antidiabetic Plants: Bauhinia forficata and Cissus sicyoides

    Directory of Open Access Journals (Sweden)

    NAJEH M KHALIL

    2008-01-01

    Full Text Available There is abundant evidence that reactive oxygen species are implicated in several physiological and pathological processes. To protect biological targets from oxidative damage, antioxidants must react with radicáis and other reactive species faster than biological substrates do. The aim of the present study was to determine the in vitro antioxidant activity of aqueous extracts from leaves of Bauhinia forficata Link (Fabaceae - Caesalpinioideae and Cissus sicyoides L. (Vitaceae (two medicinal plants used popularly in the control of diabetes mellitus, using several different assay systems, namely, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS decolorization, superoxide anión radical (0(2•- scavenging and myeloperoxidase (MPO activity. In the ABTS assay for total antioxidant activity, B. forficata showed IC50 = 8.00±0.07 ?g/mL, while C. sicyoides showed IC50 = 13.0±0.2 ?g/mL. However, the extract of C. sicyoides had a stronger effect on 0(2•- (IC50 = 60.0±2.3 ?g/mL than the extract of B. forficata (IC50 = 90.0±4.4 ?g/ mL. B. forficata also had a stronger inhibitory effect on MPO activity, as measured by guaiacol oxidation, than C. sicyoides. These results indicate that aqueous extracts of leaves of B. forficata and C. sicyoides are a potential source of natural antioxidants and may be helpful in the prevention of diabetic complications associated with oxidative stress.

  16. Impact of Lactic Acid on Cell Proliferation and Free Radical Induced Cell Death in Monolayer Cultures of Neural Precursor Cells

    OpenAIRE

    Lampe, Kyle J.; Namba, Rachael M.; Silverman, Tyler R.; Bjugstad, Kimberly B.; MAHONEY, MELISSA J.

    2009-01-01

    Biomaterials prepared from polyesters of lactic acid and glycolic acid, or a mixture of the two, degrade in the presence of water into the naturally occurring metabolites, lactic acid and glycolic acid. While the lactic acid degradation product that is released from biomaterials is well-tolerated by the body, lactic acid can influence the metabolic function of cells; it can serve as an energy substrate for cells, and has been shown to have antioxidant properties. Neural precursor cells, a cel...

  17. In Vitro Antioxidant Activities, Free Radical Scavenging Capacity, and Tyrosinase Inhibitory of Flavonoid Compounds and Ferulic Acid from Spiranthes sinensis (Pers. Ames

    Directory of Open Access Journals (Sweden)

    Chung Pin Liang

    2014-04-01

    Full Text Available In this study, ultrasound-assisted extraction (UAE and other methods of extracting flavonoid compounds and ferulic acid (FA from S. sinensis were investigated. Five different extraction methods, including water extraction (W, water extraction using UAE (W+U, 75% ethanol extraction (E, 75% ethanol extraction using UAE (E+U, and supercritical CO2 extraction (SFE were applied in the extraction of bioactive compounds (flavonoids and ferulic acid in order to compare their efficiency. The highest yield of flavonoids (4.28 mg/g and ferulic acid (4.13 mg/g content was detected in the E+U extract. Furthermore, S. sinensis extracts obtained by E+U show high antioxidant activity, and IC50 values of 0.47 mg/mL for DPPH radicals and 0.205 mg/mL for metal chelating activity. The total antioxidant assay shows superoxide radical scavenging capacity and in vitro mushroom tyrosinase inhibition in a dose-dependent manner, suggesting that E+U can be used for extraction of bioactive compounds from S. sinensis.

  18. Determination of protective properties of Bardejovske Kuple spa curative waters by rotational viscometry and ABTS assay

    OpenAIRE

    TOPOLSKA Dominika; VALACHOVA Katarina; HRABAROVA Eva; Rapta, Peter; BANASOVA Maria; JURNANEK Ivo; SOLTES Ladislav

    2014-01-01

    Mineral waters from Bardejovske Kupele spa are natural, strongly mineralized, with healing effects. They are classified as hydrocarbonic - containing chloride and sodium - carbonic, cold, hypotonic, with a relatively high boric acid content. Potential anti-oxidative effects of curative waters from Bardejovske Kupele were investigated against the hyaluronan (HA) degradation. High-molar-mass HA was exposed to the action of ascorbate and cupric ions, which initiate free-radical chain degradation...

  19. A New Hyaluronic Acid Derivative Obtained from Atom Transfer Radical Polymerization as a siRNA Vector for CD44 Receptor Tumor Targeting.

    Science.gov (United States)

    Palumbo, Fabio Salvatore; Bavuso Volpe, Antonella; Bongiovì, Flavia; Pitarresi, Giovanna; Giammona, Gaetano

    2015-11-01

    Two derivatives of hyaluronic acid (HA) have been synthesized by atom transfer radical polymerization (ATRP), starting from an ethylenediamino HA derivative (HA-EDA) and by using diethylaminoethyl methacrylate (DEAEMA) as a monomer for polymerization. Both samples, indicated as HA-EDA-pDEAEMA a and b, are able to condense siRNA, as determined by gel retardation assay and resulting complexes show a size and a zeta potential value dependent on polymerization number, as determined by dynamic light scattering measurements. In vitro studies performed on HCT 116 cell line, that over express CD44 receptor, demonstrate a receptor mediated uptake of complexes, regardless of their surface charge. PMID:26136372

  20. A novel detection approach based on chromophore-decolorizing with free radical and application to photometric determination of copper with acid chrome dark blue.

    Science.gov (United States)

    Gao, Hong-Wen; Chen, Fang-Fang; Chen, Ling; Zeng, Teng; Pan, Lu-Ting; Li, Jian-Hua; Luo, Hua-Fei

    2007-03-21

    A novel detection approach named chromophore-decolorizing with free radicals is developed for determination of trace heavy metal. The hydroxyl radicals (HO) generated from Fe(III) and hydrogen peroxide will oxidize the free chromophore into almost colorless products. The copper-acid chrome dark blue (ACDB) complexation was investigated at pH 5.07. In the presence of Fe(III) and hydrogen peroxide, the excess ACDB was decolorized in the Cu-ACDB reaction solution, and the final solution contained only one color compound, the Cu-ACDB complex. After oxidation of free hydroxyl radicals, the complexation becomes sensitive and selective and it has been used for the quantitation of trace amounts of Cu(II) dissolved in natural water. Beer's law is obeyed in the range from 0 to 0.500 microg mL(-1) Cu(II) and the limit of detection is only 6 microg L(-1) Cu(II). Besides, the Cu-ACDB complex formed was characterized. PMID:17386753

  1. Primary steps in the reaction of OH radicals with amino acids at low temperatures in Laval nozzle expansions: perspectives from experiment and theory.

    Science.gov (United States)

    Liessmann, Matthias; Hansmann, Björn; Blachly, Patrick G; Francisco, Joseph S; Abel, Bernd

    2009-07-01

    Recent work has focused on the damaging effects of free radicals on biological molecules. This study investigates the kinetics of the attack of OH radicals on L-alanine ethyl ester in the gas phase in cold beams of Laval nozzle expansions. Experiments and high-level theory are used to understand the preferred site of attack by the OH radical. Optimizations of L-alanine and L-alanine ethyl ester show that the essential transition state features for hydrogen abstraction off the C(alpha), C(beta), and N are similar. The energetics show that for L-alanine, the C(alpha)-site, C(beta)-site, and N-site transition states are all below the reactants level. For L-alanine ethyl ester, however, the energetics for hydrogen abstraction off the C(alpha) and N are the preferred site of reaction. These findings are supported by the observed negative temperature dependence of the rate constants of OH with alanine ethyl ester in Laval nozzle expansion experiments. More importantly, both the experiments and theory show that L-alanine ethyl ester provides a good model for gas phase studies of the amino acids such as L-alanine. PMID:19552478

  2. Dosimetric Applications of Electronic Paramagnetic Resonance Measurements of Free Radicals Formed in Amino Acids: Construction of a Tissue-Equivalent Dosimeter Based on Alanine

    International Nuclear Information System (INIS)

    In the case of amino acids rupture of the molecules due to the action of radiation is found to produce free radicals. The number of these radicals can be measured by means of an electronic paramagnetic resonance spectrometer and this number is proportional to the dose absorbed. Alanine has been used for this purpose since it possesses this property over a wide dose range (from 10 to 5 x 106 rads). The present paper covers essentially the following points: (a) Pre-irradiation effect in non-irradiated alanine: this dose limits the minimum measurable dose to approximately 10 rads. The origin of this dose and means of re- ducing it have been studied; (b) Energy response of the alanine: by virtue of the close similarity of its composition to that of tissue, this dosimeter has a good energy response for gamma radiations; the loss of efficiency at low energies can be corrected by the addition of a higher Z material (Ba or Ca); (c) Response to neutrons: with neutrons the radical yield is lower than in the case of gamma radiation, although this yield can be increased by adding a hydrogenated substance (paraffin); (d) Construction of a dosimeter in pellet form: the addition of paraffin improves the response to neutrons and enables moulded pellets of the mixture to be produced. These are easier to use than alanine in powder form and the dosimeters can be produced in any desired form. (author)

  3. Effects of chloride ion on degradation of Acid Orange 7 by sulfate radical-based advanced oxidation process: implications for formation of chlorinated aromatic compounds.

    Science.gov (United States)

    Yuan, Ruixia; Ramjaun, Sadiqua N; Wang, Zhaohui; Liu, Jianshe

    2011-11-30

    Sodium chloride is a common salt used during textile wet processes. Here a dual effect of chloride (i.e. inhibitory and accelerating effect) on azo dye (Acid Orange 7, AO7) degradation in an emerging cobalt/peroxymonosulfate (Co/PMS) advanced oxidation process (AOP) was reported. Compared to OH-based AOPs, high concentrations of chloride (>5mM) can significantly enhance dye decoloration independent of the presence of the Co(2+) catalyst, but did greatly inhibit dye mineralization to an extent which was closely dependent upon the chloride content. Both UV-vis absorbance spectra and AOX determination indicated the formation of some refractory byproducts. Some chlorinated aromatic compounds, including 3-chloroisocoumain, 2-chloro-7-hydroxynaphthalene, 1,3,5-trichloro-2-nitrobenzene and tetrachlorohydroquione, were identified by GC-MS measurement in both Co/PMS/Cl(-) and PMS/Cl(-) reaction systems. Based on those experimental results, two possible branched (SO(4)(-)radical-based and non-radical) reaction pathways are proposed. This is one of the very few studies dealing with chlorinated organic intermediates formed via chlorine radical/active chlorine species (HOCl/Cl(2)) attack on dye compounds. Therefore, this finding may have significant technical implications for utilizing Co/PMS regent to detoxify chloride-rich azo dyes wastewater. PMID:21968121

  4. OH-radical induced degradation of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 4-chloro-2-methylphenoxyacetic acid (MCPA): A pulse radiolysis and gamma-radiolysis study

    International Nuclear Information System (INIS)

    The reactions of ·OH, H· and eaq? with 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 4-chloro-2-methylphenoxyacetic acid (MCPA) were studied by pulse radiolysis. The site of ·OH-radicals addition to the aromatic ring of 2,4,5-T was found to be—C1: ?18%, C2/C4/C5: total ?28% and C3/C6: total ?41%. The overall rate constants with OH-radicals were k(·OH+2,4,5-T)=6.4 (±0.5)×109 mol dm?3 s?1 and k(·OH+MCPA)=8.5 (±0.8)×109 mol dm?3 s?1. The radiation induced decomposition of the pesticides, chloride- and product formation (phenolic compounds, aliphatic acids) was studied by gamma radiolysis as a function of dose. A mechanism for acetate formation is discussed. The presence of oxygen during irradiation affected the decomposition rate only indiscernibly, however, chloride elimination, ring fragmentation (formation of aliphatic acids), TOC- and toxicity reduction were strongly enhanced. For complete removal of 500 ?mol dm?3 herbicides a dose of ?4 kGy was required. Using air saturation during irradiation a reduction of 37–40% of the TOC was observable at 5 kGy, detoxification (luminescence inhibition <20%) was achieved with 10 kGy. - Highlights: ? Degradation of phenoxyacetic acid herbicides by ionizing radiation. ? Primary pattern of OH-radical addition to the aromatic ring of 2,4,5-T. ? Strong influence of oxygen concentration on chloride elimination, formation of phenolic intermediates and aliphatic acids. ? Detoxification of 500 ?mol herbicide solutions is obtained with 10 kGy.

  5. A 1H NMR Investigation of the Interaction between Phenolic Acids Found in Mango (Manguifera indica cv Ataulfo) and Papaya (Carica papaya cv Maradol) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) Free Radicals

    Science.gov (United States)

    López-Martínez, Luis M.; Santacruz-Ortega, Hisila; Navarro, Rosa-Elena; Sotelo-Mundo, Rogerio R.; González-Aguilar, Gustavo A.

    2015-01-01

    The benefits of phenolic acids on human health are very often ascribed to their potential to counteract free radicals to provide antioxidant protection. This potential has been attributed to their acidic chemical structure, which possesses hydroxyl groups in different positions. Phenolic acids can interact between themselves and exhibit an additive, antagonistic or synergistic effect. In this paper, we used 1H NMR to analyze the interactions and mechanisms that are present in major phenolic acids found in mango (gallic, protocatechuic, chlorogenic and vanillic acids) and papaya (caffeic, ferulic and p-coumaric acids), and the DPPH radical was used to evaluate the effect of the antioxidant mixtures. The interactions were found to occur via hydrogen bonds between the -OH and -COOH groups. Moreover, the phenolic acids exhibit two types of mechanisms for the neutralization of the DPPH radical. According to the results, these two mechanisms are Hydrogen Atom Transfer (HAT) and Single Electron Transfer (SET). The ability of the phenolic acid to neutralize the DPPH radical decreases in the following order in mango: gallic > chlorogenic > protocatechuic > vanillic. Moreover, within the acids found in papaya, the order was as follows: caffeic > p-coumaric > ferulic. PMID:26559189

  6. Aqueous-phase photolysis of biacetyl (An ?-dicarbonyl compound): A sink for biacetyl, and a source of acetic acid, peroxyacetic acid, hydrogen peroxide, and the highly oxidizing acetylperoxyl radical in aqueous aerosols, fogs, and clouds

    Science.gov (United States)

    Faust, Bruce C.; Powell, Kendall; Rao, C. Janakiram; Anastasio, Cort

    Aqueous-phase photolysis of biacetyl represents a heretofore uncharacterized sink for biacetyl and source of organic acids and peroxides to aqueous aerosols, and fog and cloud drops. The photolysis half-life of aqueous-phase biacetyl is approximately 1.0-1.6 h for a solar zenith angle of 36° (midday equinox sunlight in Durham, NC). Major products of aqueous biacetyl photolysis are acetic acid, peroxyacetic acid, and hydrogen peroxide. Pyruvic acid and methylhydroperoxide are minor photoproducts. Common atmospheric reductants (H-atom donors), such as formate, formaldehyde, glyoxal, phenol (as a model for phenolic compounds) and ?- D-glucose (as a model for carbohydrates), substantially increase the quantum yields of peroxyacetic acid Formate also significantly increases the quantum yields of hydrogen peroxide. The highly oxidizing acetylperoxyl radical is proposed as a key intermediate in the photolysis of aqueous biacetyl. The sources and reactions of acetylperoxyl radicals in aqueous aerosols, fogs, and clouds should be investigated in future studies of atmospheric water-drop chemistry.

  7. Studies on the syntheses, structural characterization, antimicrobial-, and DPPH radical scavenging activity of the cocrystals caffeine:cinnamic acid and caffeine:eosin dihydrate

    Science.gov (United States)

    Suresh Kumar, G. S.; Seethalakshmi, P. G.; Bhuvanesh, N.; Kumaresan, S.

    2013-10-01

    Two organic cocrystals namely, caffeine:cinnamic acid [(caf)(ca)] (1) and caffeine:eosin dihydrate [(caf)(eos)]·2H2O (2) were synthesized and studied by FT-IR, TGA/DTA, and single crystal XRD. The crystal system of cocrystal 1 is triclinic with space group P-1 and Z = 2 and that of cocrystal 2 is monoclinic with space group P21/C and Z = 4. An imidazole-carboxylic acid synthon is observed in the cocrystal 1. The intermolecular hydrogen bond, O-H⋯N and π-π interactions play a major role in stabilizing 1 whereas the intermolecular hydrogen bonds, O-H⋯O, O-H⋯N, and intramolecular hydrogen bond, O-H⋯Br; along with π-π interactions together play a vital role in stabilizing the structure of 2. The antimicrobial- and DPPH radical scavenging activities of both the cocrystals were studied.

  8. Efficacies of ABT-773, a New Ketolide, against Experimental Bacterial Infections

    OpenAIRE

    Mitten, M. J.; Meulbroek, J; Nukkala, M.; Paige, L; Jarvis, K.; Oleksijew, A.; Tovcimak, A.; Hernandez, L.; Alder, J D; P. Ewing; Or, Y. S.; Ma, Z.; Nilius, A. M.; Mollison, K.; Flamm, R. K.

    2001-01-01

    ABT-773 is a novel ketolide effective against antibacterial-resistant respiratory tract pathogens. The pharmacokinetic profile of ABT-773 was studied in rats and consisted of a mean peak concentration in plasma of 1.07 ?g/ml and an area under the concentration-time curve (AUC) of 12.03 ?g?·?h/ml when the compound was delivered at a dose of 25 mg/kg of body weight. It concentrated in rat lung tissue, with a lung tissue-to-plasma ratio of 29 based on the AUC. In acute systemic infections in mic...

  9. Carotenoid Radicals and Radical Ions

    Science.gov (United States)

    El-Agamey, Ali; McGarvey, David J.

    Various types of carotenoid-derived ions, radicals and radical ions are referred to in this Chapter and elsewhere in this Volume. The different species are defined below and their relationship to the parent carotenoid is illustrated by the example of ?-carotene (3, C40H56).

  10. In Vitro and In Vivo Enhancement of Chemoradiation Using the Oral PARP Inhibitor ABT-888 in Colorectal Cancer Cells

    Energy Technology Data Exchange (ETDEWEB)

    Shelton, Joseph W., E-mail: jwshelt@emory.edu [Department of Radiation Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Waxweiler, Timothy V.; Landry, Jerome; Gao, Huiying; Xu, Yanbo; Wang, Lanfang [Department of Radiation Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); El-Rayes, Bassel [Department of Hematology and Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States); Shu, Hui-Kuo G. [Department of Radiation Oncology, Winship Cancer Institute, Emory University, Atlanta, Georgia (United States)

    2013-07-01

    Purpose: Poly(ADP-ribose) polymerase plays a critical role in the recognition and repair of DNA single-strand breaks and double-strand breaks (DSBs). ABT-888 is an orally available inhibitor of this enzyme. This study seeks to evaluate the use of ABT-888 combined with chemotherapy and radiation therapy (RT) in colorectal carcinoma models. Methods and Materials: RT clonogenic assays were performed on HCT116 and HT29 cells treated with 5-fluorouracil, irinotecan, or oxaliplatin with or without ABT. The surviving fraction at 2 Gy and dose-modifying factor at 10% survival were analyzed. Synergism was assessed by isobologram analysis for combination therapies. ?H2AX and neutral comet assays were performed to assess the effect of therapy on DSB formation/repair. In vivo assessments were made by use of HCT116 cells in a xenograft mouse model. Tumor growth delay was measured at a volume of 500 mm{sup 3}. Results: Both lines were radiosensitized by ABT alone, and ABT further increased chemotherapy dose-modifying factors to the 1.6 to 1.8 range. All combinations were synergistic (combination indices <0.9). ABT treatment significantly increased DSB after RT (?H2AX, 69% vs 43%; P=.017) and delayed repair. We found tumor growth delays of 7.22 days for RT; 11.90 days for RT and ABT; 13.5 days for oxaliplatin, RT, and ABT; 14.17 days for 5-fluorouracil, RT, and ABT; and 23.81 days for irinotecan, RT, and ABT. Conclusion: ABT-888 radiosensitizes at similar or higher levels compared with classic chemotherapies and acts synergistically with these chemotherapies to enhance RT effects. In vivo confirmation of these results indicates a potential role for combining its use with existing chemoradiation regimens.

  11. In Vitro and In Vivo Enhancement of Chemoradiation Using the Oral PARP Inhibitor ABT-888 in Colorectal Cancer Cells

    International Nuclear Information System (INIS)

    Purpose: Poly(ADP-ribose) polymerase plays a critical role in the recognition and repair of DNA single-strand breaks and double-strand breaks (DSBs). ABT-888 is an orally available inhibitor of this enzyme. This study seeks to evaluate the use of ABT-888 combined with chemotherapy and radiation therapy (RT) in colorectal carcinoma models. Methods and Materials: RT clonogenic assays were performed on HCT116 and HT29 cells treated with 5-fluorouracil, irinotecan, or oxaliplatin with or without ABT. The surviving fraction at 2 Gy and dose-modifying factor at 10% survival were analyzed. Synergism was assessed by isobologram analysis for combination therapies. ?H2AX and neutral comet assays were performed to assess the effect of therapy on DSB formation/repair. In vivo assessments were made by use of HCT116 cells in a xenograft mouse model. Tumor growth delay was measured at a volume of 500 mm3. Results: Both lines were radiosensitized by ABT alone, and ABT further increased chemotherapy dose-modifying factors to the 1.6 to 1.8 range. All combinations were synergistic (combination indices <0.9). ABT treatment significantly increased DSB after RT (?H2AX, 69% vs 43%; P=.017) and delayed repair. We found tumor growth delays of 7.22 days for RT; 11.90 days for RT and ABT; 13.5 days for oxaliplatin, RT, and ABT; 14.17 days for 5-fluorouracil, RT, and ABT; and 23.81 days for irinotecan, RT, and ABT. Conclusion: ABT-888 radiosensitizes at similar or higher levels compared with classic chemotherapies and acts synergistically with these chemotherapies to enhance RT effects. In vivo confirmation of these results indicates a potential role for combining its use with existing chemoradiation regimens

  12. Effect of methyl mercury induced free radical stress on nucleic acids and protein: Implications on cognitive and motor functions

    OpenAIRE

    Zahir, Farhana; Rizvi, Shameem J; Haq, Soghra K; Khan, Rizwan H.

    2006-01-01

    Mercury pollution and acute neurotoxicity of mercury is well known. The recent reports suggest the adverse effect of low dose mercury, though the available literature is still silent on its mechanism. This study was therefore undertaken to probe the effect of low dose methyl mercury induced heavy metal toxicity on free radical stress and its impact on behaviour of male albino rats. Male albino rats were exposed to 1 mg/kg body wt of methylmercury chloride for seven days, on day 8 they were te...

  13. Enzyme inhibitory and radical scavenging effects of some antidiabetic plants of Turkey

    Directory of Open Access Journals (Sweden)

    Nilüfer Orhan

    2014-06-01

    Full Text Available Objective(s:Ethnopharmacological field surveys demonstrated that many plants, such as Gentiana olivieri, Helichrysum graveolens, Helichrysum plicatum ssp. plicatum, Juniperus oxycedrus ssp. oxycedrus, Juniperus  communis var. saxatilis, Viscum album (ssp. album, ssp. austriacum, are used as traditional medicine for diabetes in different regions of Anatolia. The present study was designed to evaluate the in vitro antidiabetic effects of some selected plants, tested in animal models recently. Materials and Methods: ?-glucosidase and ?-amylase enzyme inhibitory effects of the plant extracts were investigated and Acarbose was used as a reference drug. Additionally, radical scavenging capacities were determined using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid ABTS radical cation scavenging assay and total phenolic content of the extracts were evaluated using Folin Ciocalteu method. Results: H. graveolens ethanol extract exhibited the highest inhibitory activity (55.7 % ± 2.2 on ?-amylase enzyme. Additionally, J. oxycedrus hydro-alcoholic leaf extract had potent ?-amylase inhibitory effect, while the hydro-alcoholic extract of J. communis fruit showed the highest ?-glucosidase inhibitory activity (IC50: 4.4 ?g/ml. Conclusion:Results indicated that, antidiabetic effect of hydro-alcoholic extracts of H. graveolens capitulums, J. communis fruit and J. oxycedrus leaf might arise from inhibition of digestive enzymes.

  14. Radical prostatectomy

    DEFF Research Database (Denmark)

    Fode, Mikkel; Sønksen, Jens; Jakobsen, Henrik

    2014-01-01

    OBJECTIVE: The aim of this study was to compare oncological and functional outcomes between robot-assisted laparoscopic radical prostatectomy (RALP) and retropubic radical prostatectomy (RRP) during the initial phase with RALP at a large university hospital. MATERIAL AND METHODS: Patient and tumour characteristics, surgeon, nerve sparing, surgical margins and blood loss were recorded prospectively in patients who underwent RRP or RALP between April 2008 and May 2012. Patients filled out the Dani...

  15. ABT-737, Synergistically Enhances Daunorubicin-Mediated Apoptosis in Acute Myeloid Leukemia Cell Lines

    Directory of Open Access Journals (Sweden)

    Hassan Dariushnejad

    2014-03-01

    Full Text Available Purpose: Intensive chemotherapy with daunorubicin (DNR is associated with serious side effects in acute myeloid leukemia (AML patients. In this study the effect of small-molecule BH3-mimetic, ABT-737, on the sensitivity of HL60 and U937 AML cell lines was investigated. Methods: The cytotoxic effects of DNR and ABT-737, alone or in combination were assessed using MTT assay and combination index analysis. The effects of treatments on the cell proliferation was determined by trypan blue assay. ELISA cell death assay was used for measurement of apoptosis. Results: IC50 values of DNR and ABT-737 were 2.52 and 0.59 ?M for HL-60 cells line and 1.31 and 0.80 ?M for U937 cell line at 24 h, respectively. Surprisingly, combination treatment significantly lowered the IC50 values in a synergic manner in both cell lines. Moreover, treatment with a mixture of two agents had more growth inhibition effect relative to the monotherapy. Results of apoptosis assay showed that the cytotoxic effects are related to the enhancement of apoptosis. Conclusion: Our study suggests that ABT-737 synergistically enhances the cytotoxic effect of DNR in AML cell lines and therefore may be useful to overcome chemoresistance of leukemia patients.

  16. 78 FR 29367 - Access to Confidential Business Information by ABT Associates, Incorporated; Perry Johnson...

    Science.gov (United States)

    2013-05-20

    ... AGENCY Access to Confidential Business Information by ABT Associates, Incorporated; Perry Johnson Registrars, Inc.; SGS North America, Inc.; SAI Global, Inc.; Orion Registrar, Inc.; NSF-ISR International... Global; Orion Registrar, Inc.; NSF- ISR International, and T V S D America, Inc., also known as...

  17. Estudio comparativo sobre la capacidad de atrapamiento del catiónradical ABTS+. Por los aceites esenciales de especies aromáticas con alto contenido de trans-ANETOL Y ESTRAGOL

    Directory of Open Access Journals (Sweden)

    Amner Muñoz

    2007-01-01

    Full Text Available Se determinó la composición química de aceites esenciales (AEs y extractos de seis especies aromáticas con alto contenido de trans-anetol y estragol (estragón de invierno, estragón, anís estrellado, anisillo, hinojo y sígueme morado, obtenidos por hidrodestilación asistida por radiación de microondas (MWHD y destilación-extracción simultánea con solvente (SDE. La separación e identificación de los compuestos se realizó por GC-MS en columna apolar DB-5MS, comparando sus espectros de masas con los de las bases de datos ADAMS, NIST02 y Wiley138 e índices de retención de kovàts. Para todos los AEs se evaluó su capacidad del atrapamiento del catión-radical ABTS+. (ácido 2,2? -azino-bis -(3-etiltiazolina-bencenosulfónico-6.

  18. Nitrogen Oxides in the Nocturnal Boundary Layer: Chemistry of Nitrous Acid (HONO) and the Nitrate Radical (N03)

    Energy Technology Data Exchange (ETDEWEB)

    Jochen Stutz

    2005-05-24

    Summary Chemical processes occurring at night in the lowest part of the urban atmosphere, the so called nocturnal boundary layer (NBL), can influence the composition of the atmosphere during the night as well as the following day. They may impact the budgets of some of the most important pollutants, such as ozone and nitrogen oxides, as well as influence size and composition of particular matter. Few studies have thus far concentrated on the nocturnal chemistry of the urban NBL, most likely due to the strong influence of vertical transport and mixing, which requires the measurement of trace gas profiles instead of simple point observations. Motivated by our lack of observations and understanding of nocturnal chemistry, the focus of this project was the study of the vertical distribution of trace gases and the altitude dependence of nocturnal chemistry under polluted conditions through field observations and modeling studies. The analysis of three field experiments (TEXAQS, Houston, 2000; Phoenix Sunrise Ozone Experiment, 2001; NAPOX, Boston, 2002), two of which were performed in this project, showed that ozone concentrations typically increase with height in the lowest 150m, while NO2 typically decreases. NO3, the dominant nocturnal radical species, showed much higher concentrations in the upper part of the NBL, and was often not present at the ground. With the help of a one-dimensional chemical transport model, developed in this project, we found that the interaction of ground emissions of NOx and hydrocarbons, together with their vertical transport, is responsible for the vertical profiles. The dominant chemical reactions influencing ozone, NO2 and NO3 are the reaction of ozone and NO3 with freshly emitted NO. Sensitivity studies with our model showed that the magnitude of the trace gas gradients depend both on the emission rates and the vertical stability of the NBL. Observations and model analysis clearly show that nocturnal chemistry in urban areas is altitude dependent. Measurements at one altitude, for example at the ground, where most air quality monitoring stations are located, are not representative for the rest of the NBL. Our model also revealed that radical chemistry is, in general, altitude dependent at night. We distinguish three regions: an unreactive, NO rich, ground layer; an upper, O3 and NO3 dominated layer, and a reactive mixing layer, where RO2 radicals are mixed from aloft with NO from the ground. In this reactive layer an active radical chemistry and elevated OH radical levels can be found. The downward transport of N2O5 and HO2NO2, followed by their thermal decay, was also identified as a radical source in this layer. Our observations also gave insight into the formation of HONO in the NBL. Based on our field experiments we were able to show that the NO2 to HONO conversion was relative humidity dependent. While this fact was well known, we found that it is most likely the uptake of HONO onto surfaces which is R.H. dependent, rather than the NO2 to HONO conversion. This finding led to the proposal of a new NO2 to HONO conversion mechanism, which is based on solid physical chemical principles. Noteworthy is also the observation of enhanced NO2 to HONO conversion during a dust storm event in Phoenix. The final activity in our project investigated the influence of the urban canopy, i.e. building walls and surfaces, on nocturnal chemistry. For the first time the surface area of a city was determined based on a Geographical Information System database of the city of Santa Monica. The surface to volume areas found in this study showed that, in the 2 lower part of the NBL, buildings provide a much larger surface area than the aerosol. In addition, buildings take up a considerable amount of the volume near the ground. The expansion of our model and sensitivity studies based on the Santa Monica data revealed that the surface area of buildings considerably influences HONO levels in urban areas. The volume reduction leads to a decrease of O3 and an increase of NO2 near the ground due to the stronger impact o

  19. Pulmonary delivery of a dopamine D-1 agonist, ABT-431, in dogs and humans.

    Science.gov (United States)

    Zheng, Y; Marsh, K C; Bertz, R J; El-Shourbagy, T; Adjei, A L

    1999-11-30

    The purpose of this study was to evaluate the feasibility of intrapulmonary delivery of ABT-431, a selective D1 receptor agonist. Following intratracheal instillation of the drug solution, the lung bioavailability was found to be approximately 75% in dogs. An aerosol suspension formulation was then developed by dispersing the drug in tetrafluoroethane, HFC-134a, with the aid of poloxamer 124 and vitamin E. This ABT-431 MDI aerosol formulation showed about 40% of the particles emitted from the valve and actuator system to be under 5 microm in diameter. Also, the primary package (15 mL aluminum container, DF10/ACT-150 valve, and Micron-4-actuator with the orifice 0.4 mm) was satisfactory for accurate and reproducible dosimetry. Using tracheostomized beagle dogs, the C(max) following tracheal administration of 5 mg aerosolized ABT-431 was found to be 13.3+/-0.9 ng ml(-1) and the AUC(0-24) was estimated at 33.2+/-10.6 h ng ml(-1). The lung bioavailability of the aerosolized drug was 34% compared to intravenous injection in dogs. In humans, results from a single rising dose study demonstrated that rapid absorption of ABT-431 following oral inhalation administration resulted in a dose-dependent increase in the area under the plasma-time curve at dosage levels between 3.3 and 13.2 mg. There is a possibility of up to 25% absorption of the drug from human lung. Thus, pulmonary bioavailability of ABT-431 is significantly greater than that of oral administration. Also, these findings suggest that small and lipophilic compounds, especially with hepatic first pass effect, may be effectively delivered systemically using oral inhalation aerosols. PMID:10564839

  20. THERMOCHEMISTRY OF HYDROCARBON RADICALS

    Energy Technology Data Exchange (ETDEWEB)

    Kent M. Ervin, Principal Investigator

    2004-08-17

    Gas phase negative ion chemistry methods are employed to determine enthalpies of formation of hydrocarbon radicals that are important in combustion processes and to investigate the dynamics of ion-molecule reactions. Using guided ion beam tandem mass spectrometry, we measure collisional threshold energies of endoergic proton transfer and hydrogen atom transfer reactions of hydrocarbon molecules with negative reagent ions. The measured reaction threshold energies for proton transfer yield the relative gas phase acidities. In an alternative methodology, competitive collision-induced dissociation of proton-bound ion-molecule complexes provides accurate gas phase acidities relative to a reference acid. Combined with the electron affinity of the R {center_dot} radical, the gas phase acidity yields the RH bond dissociation energy of the corresponding neutral molecule, or equivalently the enthalpy of formation of the R{center_dot} organic radical, using equation: D(R-H) = {Delta}{sub acid}H(RH) + EA(R) - IE(H). The threshold energy for hydrogen abstraction from a hydrocarbon molecule yields its hydrogen atom affinity relative to the reagent anion, providing the RH bond dissociation energy directly. Electronic structure calculations are used to evaluate the possibility of potential energy barriers or dynamical constrictions along the reaction path, and as input for RRKM and phase space theory calculations. In newer experiments, we have measured the product velocity distributions to obtain additional information on the energetics and dynamics of the reactions.

  1. Identification and quantification of phytochemical composition and anti-inflammatory and radical scavenging properties of methanolic extracts of Chinese propolis.

    Science.gov (United States)

    Shi, Haiming; Yang, Haisha; Zhang, Xiaowei; Yu, Liangli Lucy

    2012-12-19

    Fifteen propolis samples collected from different regions of China were investigated and compared for their phytochemical composition and anti-inflammatory and radical scavenging properties. Eleven compounds including caffeic, p-coumaric, ferulic, isoferulic, and 3,4-dimethylcaffeic acids, pinobanksin, chrysin, pinocembrin, galangin, pinobanksin 3-acetate, and caffeic acid phenylethyl ester were quantified for the 15 propolis samples using a UHPLC method, whereas 38 compounds were identified by UPLC/Q-TOF-MS. The 15 propolis samples significantly differed in their total phenolic and total flavonoid contents, as well as their phytochemical profiles. The methanol extracts of propolis also showed significant anti-inflammatory effects in LPS-stimulated RAW 264.7 mouse macrophage cells at 10 ?g propolis extract/mL concentration. Additionally, the propolis samples differed in their DPPH, ABTS cation, hydroxyl, and peroxide radical scavenging capacities and ferric reducing abilities. The results from this study may be used to improve the commercial production and consumption of Chinese propolis products. PMID:23176258

  2. Effects of Extraction and Processing Methods on Antioxidant Compound Contents and Radical Scavenging Activities of Laver (Porphyra tenera).

    Science.gov (United States)

    Hwang, Eun-Sun; Thi, Nhuan Do

    2014-01-01

    Laver is one of the most consumed edible red algae seaweeds in the genus Porphyra. Laver is primarily prepared in the form of dried, roasted, and seasoned products. We investigated the total polyphenol and flavonoid contents of laver products, and evaluated the in vitro antioxidant properties of solvent extracts from commercially processed laver products. Significant differences in the concentration of phenolic compounds were found among differently processed laver. The total phenolic content for laver extracts ranged from 10.81 mg gallic acid equivalent (GAE)/g extract to 32.14 mg GAE/g extract, depending on extraction solvent and temperature. Laver extracts contained very few flavonoids (0.55 mg catechin equivalent/g extracts to 1.75 mg catechin equivalent/g extracts). 2,2-Diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS), hydroxyl radical, and superoxide anion scavenging assays were used to determine the radical scavenging capacities of laver extracts. These assays revealed that the processing method and extraction condition affected the antioxidant potentials of laver. Antioxidant activity of dried laver, roasted laver, and seasoned laver increased in a concentration-dependent manner (100~1,000 ?g/mL). The radical scavenging activities of 37°C and 100°C water extracts were lower than that of a 37°C 70% ethanol extract. The highest radical scavenging capacity was observed in the 37°C 70% ethanol extracts of dried laver, roasted laver, and seasoned laver. Overall, these results support that notion that laver contains bioactive compounds, such as polyphenols and flavonoids, which may have a positive effect on health. PMID:24772408

  3. Evaluation of in vitro antioxidant activity and free radical scavenging potential of variety of Tagetes erecta L. flowers growing in Bulgaria

    Directory of Open Access Journals (Sweden)

    Miglena Valyova

    2012-08-01

    Full Text Available Summary. Marigold (Tagetes erecta L. is well known for its antimicrobial, antiseptic, wound and ulcer healing, antiinflammatory, antioxidant and antiviral properties, and it has a long history of being used as an herbal remedy. T. erecta L. produces a variety of substances that possess pharmacological effects and antioxidant activity. The present study was therefore aimed to analyze the antioxidant activity of extracts and fractions of T. erecta L. flowers, cultivated in Bulgaria. Radical scavenging potential was determined using two different in vitro assays. 1, 1-diphenyl-2-picrylhydrazyl (DPPH and 2, 2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS radicals. The ethyl acetate fraction of T. erecta L. ethanol extract was found to be the most effective in both assays, DPPH (IC50 4.3±0.4 ?g/ml and ABTS (0.8±0.2 TEAC. The greatest total phenolic content was detected in EtOAc fraction from EtOH extract (517.8 mg/g GAE. It was obtained high quantity of ascorbate and ascorbate/dehydroascorbate ratio more than 1. The quantity of glutathione reduced is low and glutathione reduced/glutathione oxidized ratio was lower than 1. A correlation between radical scavenging capacities of samples with total phenolic compound content was observed. The present study revealed that the EtOAc fraction effectively show the best ability to scavenge the free radicals. Industrial relevance. Herbal medicines have gained increasing attention worldwide for the treatment of chronic diseases because of their effectiveness and small side effects as compared to synthetic drugs.Recently, an attention has been directed toward the antioxidant phytochemicals which have proved as protective against cardiovascular diseases and cancer, associated with overproduction of reactive oxygen species. The present investigations focus has been to discover plant extracts and fractions from T. erecta useful to prevent chronic degenerative diseases, especially those mediated by free radicals damages. The great antioxidant activity indicates the potential of the extracts as a source of natural antioxidants or nutraceuticals with possible application to reduce oxidative stress with consequent health benefits. Keywords. Tagetes erecta L.; in vitro antioxidant activity; free radical scavenging potential; phenols; flavonoids; ascorbate, glutathione.

  4. Phenolic acid content and radical scavenging activity of extracts from medlar (Mespilus germanica L.) fruit at different stages of ripening.

    Czech Academy of Sciences Publication Activity Database

    Grúz, Ji?í; Ayaz, F. A.; Torun, H.; Strnad, Miroslav

    2011-01-01

    Ro?. 124, ?. 1 (2011), s. 271-277. ISSN 0308-8146 R&D Projects: GA AV ?R KAN200380801 Institutional research plan: CEZ:AV0Z50380511 Keywords : Phenolic acid s * HPLC * Mass spectrometry * Fruit * Ripening Subject RIV: EF - Botanics Impact factor: 3.655, year: 2011

  5. Understanding sensitivity to BH3 mimetics: ABT-737 as a case study to foresee the complexities of personalized medicine

    Directory of Open Access Journals (Sweden)

    Stamelos Vasileios A

    2012-08-01

    Full Text Available Abstract BH3 mimetics such as ABT-737 and navitoclax bind to the BCL-2 family of proteins and induce apoptosis through the intrinsic apoptosis pathway. There is considerable variability in the sensitivity of different cells to these drugs. Understanding the molecular basis of this variability will help to determine which patients will benefit from these drugs. Furthermore, this understanding aids in the design of rational strategies to increase the sensitivity of cells which are otherwise resistant to BH3 mimetics. We discuss how the expression of BCL-2 family proteins regulates the sensitivity to ABT-737. One of these, MCL-1, has been widely described as contributing to resistance to ABT-737 which might suggest a poor response in patients with cancers that express levels of MCL-1. In some cases, resistance to ABT-737 conferred by MCL-1 is overcome by the expression of pro-apoptotic proteins that bind to apoptosis inhibitors such as MCL-1. However, the distribution of the pro-apoptotic proteins amongst the various apoptosis inhibitors also influences sensitivity to ABT-737. Furthermore, the expression of both pro- and anti-apoptotic proteins can change dynamically in response to exposure to ABT-737. Thus, there is significant complexity associated with predicting response to ABT-737. This provides a paradigm for the multiplicity of intricate factors that determine drug sensitivity which must be considered for the full implementation of personalized medicine.

  6. The effects of ABT-491 administration on visual evoked potentials in rat model of hypoxic ischemic brain injury - Original Article

    Directory of Open Access Journals (Sweden)

    Tolgay Ergeno?lu

    2010-12-01

    Full Text Available Aim: In the present study, we aimed to investigate the effects of ABT-491 on visual evoked potentials (VEP in rat model of hypoxic ischemic brain injury (HIBI. Material and Method: Fifty-seven male Wistar newborn rats were used in this study. Animals were divided into three groups randomly. HIBI was formed on postnatal seventh day according to modified Levine-Rice model in 1st (n=18 and 2nd (n=20 groups. Third group (n=19 served as sham group. After HIBI, ABT-491 was applied intraperitoneally to rats in the 1st group (ABT group and saline was administered to the rats in the 2nd group (saline group. On postnatal 16th weeks, VEPs were recorded from Ag-AgCl disc electrode placed on the occipital region. Results: The latencies of P3 wave were shorter in the ABT group than the saline group (p<0.05. Peak-to-peak amplitudes of P2-N2 and N2-P3 were smaller in the ABT and saline groups compared to the sham group (for all pairwise comparisons p<0.001.Conclusions:It was concluded that HIBI caused a decrement in amplitudes of VEP responses and this change could not be ameliorated with ABT-491. However, shortening in latencies of P3 wave could be ameliorated with ABT-491 treatment after HIBI was formed. (Turk Arch Ped 2010; 45: 319-23

  7. A peripherally acting, selective T-type calcium channel blocker, ABT-639, effectively reduces nociceptive and neuropathic pain in rats.

    Science.gov (United States)

    Jarvis, Michael F; Scott, Victoria E; McGaraughty, Steve; Chu, Katharine L; Xu, Jun; Niforatos, Wende; Milicic, Ivan; Joshi, Shailen; Zhang, Qingwei; Xia, Zhiren

    2014-06-15

    Activation of T-type Ca²? channels contributes to nociceptive signaling by facilitating action potential bursting and modulation of membrane potentials during periods of neuronal hyperexcitability. The role of T-type Ca²? channels in chronic pain is supported by gene knockdown studies showing that decreased Ca(v)3.2 channel expression results in the loss of low voltage-activated (LVA) currents in dorsal root ganglion (DRG) neurons and attenuation of neuropathic pain in the chronic constriction injury (CCI) model. ABT-639 is a novel, peripherally acting, selective T-type Ca²? channel blocker. ABT-639 blocks recombinant human T-type (Ca(v)3.2) Ca²? channels in a voltage-dependent fashion (IC?? = 2 ?M) and attenuates LVA currents in rat DRG neurons (IC?? = 8 ?M). ABT-639 was significantly less active at other Ca²? channels (e.g. Ca(v)1.2 and Ca(v)2.2) (IC?? > 30 ?M). ABT-639 has high oral bioavailability (%F = 73), low protein binding (88.9%) and a low brain:plasma ratio (0.05:1) in rodents. Following oral administration ABT-639 produced dose-dependent antinociception in a rat model of knee joint pain (ED?? = 2 mg/kg, p.o.). ABT-639 (10-100 mg/kg, p.o.) also increased tactile allodynia thresholds in multiple models of neuropathic pain (e.g. spinal nerve ligation, CCI, and vincristine-induced). [corrected]. ABT-639 did not attenuate hyperalgesia in inflammatory pain models induced by complete Freund's adjuvant or carrageenan. At higher doses (e.g. 100-300 mg/kg) ABT-639 did not significantly alter hemodynamic or psychomotor function. The antinociceptive profile of ABT-639 provides novel insights into the role of peripheral T-type (Ca(v)3.2) channels in chronic pain states. PMID:24726441

  8. Modeling nitrous acid and its impact on ozone and hydroxyl radical during the Texas Air Quality Study 2006

    OpenAIRE

    B. H. Czader; Rappenglück, B.; P. Percell; Byun, D.W.; Ngan, F.; Kim, S.

    2012-01-01

    Nitrous acid (HONO) mixing ratios for the Houston metropolitan area were simulated with the Community Multiscale Air Quality (CMAQ) model for an episode during the Texas Air Quality Study (TexAQS) II in August/September 2006 and compared to in-situ MC/IC (mist-chamber/ion chromatograph) and long path DOAS (Differential Optical Absorption Spectroscopy) measurements at three different altitudes. Several HONO sources were accounted for in simulations, such as gas phase formation, direct emission...

  9. The BCL2 inhibitor ABT-199 significantly enhances imatinib-induced cell death in chronic myeloid leukemia progenitors

    OpenAIRE

    Ko, Tun Kiat; Chuah, Charles T.H.; Huang, John W. J.; Ng, King-Pan; Ong, S. Tiong

    2014-01-01

    BCR-ABL1-specific tyrosine kinase inhibitors prolong the life of patients with chronic myeloid leukemia (CML) but cannot completely eradicate CML progenitors. The BH3 mimetic, ABT-263, targets prosurvival BCL2 family members, and has activity against CML progenitors. However, the inhibitory effect of ABT-263 on BCL-XL, which mediates platelet survival, produces dose-limiting thrombocytopenia. A second-generation BH3 mimetic, ABT-199, has been developed to specifically bind BCL2 but not BCL-XL...

  10. Comparative evaluation of free radical scavenging activity of Boerhaavia diffusa root extracts (BDRE and determination of dose effectivity against radiation induced damages in Swiss albino mice

    Directory of Open Access Journals (Sweden)

    P Dhakar

    2012-12-01

    Full Text Available Summary: Purpose of the study was to evaluate free radical scavenging activity (FRSA of root extracts of Boerhaavia diffusa in different solvents and to examine its dose effectivity against radiation induced damages in Swiss albino mice. Scavenging activities of aqueous, ethanolic and hydroethanolic extracts of B. diffusa roots were evaluated by DPPH (2, 2-diphenyl-1 picryl hydrazyl, ABTS (2,2’-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid and NO (nitric oxide assay to find the most effective extract and results were expressed as IC50. To find the most effective dose, hydroethanolic root extract (50:50 of B. diffusa was orally administered to Swiss albino mice at the dose of 250, 500 and 1000 mg/Kg.body.weight for 15 consecutive days prior to irradiation with 8 Gy gamma radiation. Results indicates that hydroethanolic extract exhibited the highest free radical scavenging activity in DPPH., ABTS.+ and NO. assays showing IC50 as 293.77, 43.62 and 32.58 µg/ml, respectively. Reduced symptoms of radiation sickness, decline in body weight and mortality were minimum when mice were pre-treated with hydroethanolic extract at the dose of 1000 mg/Kg.body.weight prior to irradiation with 8 Gy gamma radiation as compared to mice pre-treated with extract at  the dose of 250 and 500 mg/Kg.body.weight prior to irradiation with same dose of radiation. Thus, it was Concluded that certain phenolic constituents of B. diffusa roots like quercitin, caeffic acid, kempferol etc. and their derivatives act as antioxidant compounds confirming B. diffusa roots a potential source of antioxidant agent. Industrial Relevance: Having noticed with the importance of phytochemicals including flavonoids and phenolic acids as contributing factors to the antioxidant activity and common use of roots of Boerhaavia diffusa in majority of medicinal aspects can be responsible in curing oxidative stress related diseases in human beings. This study perhaps will be helpful in development of the effective drug for providing protection to biological systems against free radical induced damage. Keywords: Radioprotection, Boerrhavia diffusa, Free Radical Scavenging Activity, Dose Reduction Factor, Antioxidants.

  11. The wheat cytochrome oxidase subunit II gene has an intron insert and three radical amino acid changes relative to maize

    OpenAIRE

    Bonen, Linda; Boer, Poppo H.; GRAY, MICHAEL W.

    1984-01-01

    We have determined the sequence of the wheat mitochondrial gene for cytochrome oxidase subunit II (COII) and find that its derived protein sequence differs from that of maize at only three amino acid positions. Unexpectedly, all three replacements are non-conservative ones. The wheat COII gene has a highly-conserved intron at the same position as in maize, but the wheat intron is 1.5 times longer because of an insert relative to its maize counterpart. Hybridization analysis of mitochondrial D...

  12. The BH3 mimetic ABT-737 increases treatment efficiency of paclitaxel against hepatoblastoma

    International Nuclear Information System (INIS)

    The primary goal of current chemotherapy in hepatoblastoma (HB) is reduction of tumour volume and vitality to enable complete surgical resection and reduce risk of recurrence or metastatic disease. Drug resistance remains a major challenge for HB treatment. In some malignancies inhibition of anti-apoptotic pathways using small BH3 mimetic molecules like ABT-737 shows synergistic effects in combination with cystotoxic agents in vitro. Now we analysed toxicology and synergistic effects of this approach in HB cells and HB xenografts. Viability was monitored in HB cells (HUH6 and HepT1) and fibroblasts treated with paclitaxel, ABT-737 and a combination of both in a MTT assay. HUH6 xenotransplants in NOD/LtSz-scid IL2R?null mice (NSG) were treated accordingly. Tumour volume and body weight were monitored. Xenografted tumours were analysed by histology and immunohistochemistry (Ki-67 and TUNEL assay). ABT-737 reduced viability in HUH6 and HepT1 cells cultures at concentrations above 1 ?M and also enhanced the cytotoxic effect of paclitaxel when used in combination. Thereby paclitaxel could be reduced tenfold to achieve similar reduction of viability of tumour cells. In contrast no toxicity in fibroblasts was observed at the same regiments. Subcutaneous HB (HUH6) treated with paclitaxel (12 mg/kg body weight, n = 7) led to delayed tumour growth in the beginning of the experiment. However, tumour volume was similar to controls (n = 5) at day 25. Combination treatment with paclitaxel and ABT-737 (100 mg/kg, n = 8) revealed significantly 10 fold lower relative tumour volumes compared to control and paclitaxel groups. Paclitaxel dependent toxicity was observed in this mice strain. Our results demonstrate enhancement of chemotherapy by using modulators of apoptosis. Further analyses should include improved pharmacological formulations of paclitaxel and BH3 mimetics in order to reduce toxicological effects. Sensitising HB to apoptosis may also render resistant HB susceptible to established chemotherapy regimens

  13. The BH3 mimetic ABT-737 increases treatment efficiency of paclitaxel against hepatoblastoma

    Directory of Open Access Journals (Sweden)

    Fuchs Jörg

    2011-08-01

    Full Text Available Abstract Background The primary goal of current chemotherapy in hepatoblastoma (HB is reduction of tumour volume and vitality to enable complete surgical resection and reduce risk of recurrence or metastatic disease. Drug resistance remains a major challenge for HB treatment. In some malignancies inhibition of anti-apoptotic pathways using small BH3 mimetic molecules like ABT-737 shows synergistic effects in combination with cystotoxic agents in vitro. Now we analysed toxicology and synergistic effects of this approach in HB cells and HB xenografts. Methods Viability was monitored in HB cells (HUH6 and HepT1 and fibroblasts treated with paclitaxel, ABT-737 and a combination of both in a MTT assay. HUH6 xenotransplants in NOD/LtSz-scid IL2R?null mice (NSG were treated accordingly. Tumour volume and body weight were monitored. Xenografted tumours were analysed by histology and immunohistochemistry (Ki-67 and TUNEL assay. Results ABT-737 reduced viability in HUH6 and HepT1 cells cultures at concentrations above 1 ?M and also enhanced the cytotoxic effect of paclitaxel when used in combination. Thereby paclitaxel could be reduced tenfold to achieve similar reduction of viability of tumour cells. In contrast no toxicity in fibroblasts was observed at the same regiments. Subcutaneous HB (HUH6 treated with paclitaxel (12 mg/kg body weight, n = 7 led to delayed tumour growth in the beginning of the experiment. However, tumour volume was similar to controls (n = 5 at day 25. Combination treatment with paclitaxel and ABT-737 (100 mg/kg, n = 8 revealed significantly 10 fold lower relative tumour volumes compared to control and paclitaxel groups. Paclitaxel dependent toxicity was observed in this mice strain. Conclusions Our results demonstrate enhancement of chemotherapy by using modulators of apoptosis. Further analyses should include improved pharmacological formulations of paclitaxel and BH3 mimetics in order to reduce toxicological effects. Sensitising HB to apoptosis may also render resistant HB susceptible to established chemotherapy regimens.

  14. A phase I study of ABT-510 plus bevacizumab in advanced solid tumors

    International Nuclear Information System (INIS)

    Targeting multiple regulators of tumor angiogenesis have the potential to improve treatment efficacy. Bevacizumab is a monoclonal antibody directed against vascular endothelial growth factor and ABT-510 is a synthetic analog of thrombospondin, an endogenous angiogenesis inhibitor. Dual inhibition may result in additional benefit. We evaluated the safety, tolerability, and efficacy of the combination of bevacizumab plus ABT-510 in patients with refractory solid tumors. We also explored the effects of these agents on plasma-based biomarkers and wound angiogenesis. Thirty-four evaluable subjects were enrolled and received study drug. Therapy was well tolerated; minimal treatment-related grade 3/4 toxicity was observed. One patient treated at dose level 1 had a partial response and five other patients treated at the recommended phase II dose had prolonged stable disease for more than 1 year. Biomarker evaluation revealed increased levels of D-dimer, von Willebrand factor, placental growth factor, and stromal-derived factor 1 in response to treatment with the combination of bevacizumab and ABT-510. Data suggest that continued evaluation of combination antiangiogenesis therapies may be clinically useful

  15. ABT737 enhances cholangiocarcinoma sensitivity to cisplatin through regulation of mitochondrial dynamics

    International Nuclear Information System (INIS)

    Cholangiocarcinoma responses weakly to cisplatin. Mitochondrial dynamics participate in the response to various stresses, and mainly involve mitophagy and mitochondrial fusion and fission. Bcl-2 family proteins play critical roles in orchestrating mitochondrial dynamics, and are involved in the resistance to cisplatin. Here we reported that ABT737, combined with cisplatin, can promote cholangiocarcinoma cells to undergo apoptosis. We found that the combined treatment decreased the Mcl-1 pro-survival form and increased Bak. Cells undergoing cisplatin treatment showed hyperfused mitochondria, whereas fragmentation was dominant in the mitochondria of cells exposed to the combined treatment, with higher Fis1 levels, decreased Mfn2 and OPA1 levels, increased ratio of Drp1 60 kD to 80 kD form, and more Drp1 located on mitochondria. More p62 aggregates were observed in cells with fragmented mitochondria, and they gradually translocated to mitochondria. Mitophagy was induced by the combined treatment. Knockdown p62 decreased the Drp1 ratio, increased Tom20, and increased cell viability. Our data indicated that mitochondrial dynamics play an important role in the response of cholangiocarcinoma to cisplatin. ABT737 might enhance cholangiocarcinoma sensitivity to cisplatin through regulation of mitochondrial dynamics and the balance within Bcl-2 family proteins. Furthermore, p62 seems to be critical in the regulation of mitochondrial dynamics. - Highlights: • Cholangiocarcinoma may adapt to cisplatin through mitochondrial fusion. • ABT737 sensitizes cholangiocarcinoma to cisplatin by promoting fission and mitophagy. • p62 might participate in the regulation of mitochondrial fission and mitophagy

  16. Clearance of senescent cells by ABT263 rejuvenates aged hematopoietic stem cells in mice.

    Science.gov (United States)

    Chang, Jianhui; Wang, Yingying; Shao, Lijian; Laberge, Remi-Martin; Demaria, Marco; Campisi, Judith; Janakiraman, Krishnamurthy; Sharpless, Norman E; Ding, Sheng; Feng, Wei; Luo, Yi; Wang, Xiaoyan; Aykin-Burns, Nukhet; Krager, Kimberly; Ponnappan, Usha; Hauer-Jensen, Martin; Meng, Aimin; Zhou, Daohong

    2016-01-01

    Senescent cells (SCs) accumulate with age and after genotoxic stress, such as total-body irradiation (TBI). Clearance of SCs in a progeroid mouse model using a transgenic approach delays several age-associated disorders, suggesting that SCs play a causative role in certain age-related pathologies. Thus, a 'senolytic' pharmacological agent that can selectively kill SCs holds promise for rejuvenating tissue stem cells and extending health span. To test this idea, we screened a collection of compounds and identified ABT263 (a specific inhibitor of the anti-apoptotic proteins BCL-2 and BCL-xL) as a potent senolytic drug. We show that ABT263 selectively kills SCs in culture in a cell type- and species-independent manner by inducing apoptosis. Oral administration of ABT263 to either sublethally irradiated or normally aged mice effectively depleted SCs, including senescent bone marrow hematopoietic stem cells (HSCs) and senescent muscle stem cells (MuSCs). Notably, this depletion mitigated TBI-induced premature aging of the hematopoietic system and rejuvenated the aged HSCs and MuSCs in normally aged mice. Our results demonstrate that selective clearance of SCs by a pharmacological agent is beneficial in part through its rejuvenation of aged tissue stem cells. Thus, senolytic drugs may represent a new class of radiation mitigators and anti-aging agents. PMID:26657143

  17. Stability studies of ascorbic acid 2-glucoside in cosmetic lotion using surface response methodology.

    Science.gov (United States)

    Huang, Wen-Ying; Lee, Pei-Chi; Huang, Ling-Kuei; Lu, Li-Ping; Liao, Wayne C

    2013-03-15

    Ascorbic acid 2-glucoside (AA-2G) has been widely used in cream and lotion types of cosmetic products. Thus, the degradation of AA-2G caused by the temperature change and pH variation was very critical for determining the bio-functionality of cosmetics. Response surface methodology (RSM) was introduced to study the influence of temperature and pH on the stability of AA-2G. The optimal condition of retaining AA-2G with the highest stability was determined to be 55.3°C and pH 6.4. The antioxidative activities of AA-2G including DPPH and ABTS free radical scavenging activities, metal chelating activity, and reducing ability were also determined. AA-2G was a good ascorbic acid derivative which could be used in cosmetic products as an active ingredient. PMID:23416010

  18. ?-scission of ?-thioalkyl radicals. Time-resolved ESR detection in the pulse radiolysis of ?-(alkylthio)-substituted acetamide, acetic acid, and acetone

    International Nuclear Information System (INIS)

    Full text: The pulse radiolysis of aqueous solutions of ?-(methylthio)acetamide CH3SCH2C(O)NH2, yields significant quantities of acetamide radicals, CH2C(O)NH2. The acetamide radicals were identified by time-resolved electron spin resonance (TRESR), and yields of the acetamide radicals were estimated at pH 1 and pH 7. The yields of the acetamide radicals roughly track the yields of hydrogen atoms from the radiolysis of water at both pH values. At low pH, where hydrated electrons are converted in large yield to hydrogen atoms, the yield of the acetamide radicals in proportionally higher than the yield at neutral pH. Although this correspondence, between the H-atom and acetamide yields, is evidence that the H-atoms could be main precursors of the acetamide radicals, molecular orbital calculations throw doubt on this as the main reaction pathway. At pH 1, the most plausible mechanism for formation of acetamide radicals is by hydroxyl radical attack at the sulfur atom, forming hydroxysulfuranyl radicals which decay by elimination of water; the resulting sulfur radical cations, in turn, decay via deprotonation forming CH2-S-CH2C(O)NH2 which decays via ?-scission. In similar experiments, CH2COOH radicals were identified by TRESR in the pulse radiolysis of low pH aqueous solutions of CH3SCH2COOH. A third example of ?-scission is given where CH2-C(O)CH3 radicals are observed following the pulse radiolysis of CH3CH2SCH2C(O)CH3

  19. Grafting of Poly(methyl methacrylate) Brushes from Magnetite Nanoparticles Using a Phosphonic Acid Based Initiator by Ambient Temperature Atom Transfer Radical Polymerization (ATATRP)

    Science.gov (United States)

    2008-01-01

    Poly(methyl methacrylate) in the brush form is grown from the surface of magnetite nanoparticles by ambient temperature atom transfer radical polymerization (ATATRP) using a phosphonic acid based initiator. The surface initiator was prepared by the reaction of ethylene glycol with 2-bromoisobutyrl bromide, followed by the reaction with phosphorus oxychloride and hydrolysis. This initiator is anchored to magnetite nanoparticles via physisorption. The ATATRP of methyl methacrylate was carried out in the presence of CuBr/PMDETA complex, without a sacrificial initiator, and the grafting density is found to be as high as 0.90 molecules/nm2. The organic–inorganic hybrid material thus prepared shows exceptional stability in organic solvents unlike unfunctionalized magnetite nanoparticles which tend to flocculate. The polymer brushes of various number average molecular weights were prepared and the molecular weight was determined using size exclusion chromatography, after degrafting the polymer from the magnetite core. Thermogravimetric analysis, X-ray photoelectron spectra and diffused reflection FT-IR were used to confirm the grafting reaction.

  20. Synthesis and Characterization of Surface Grafted Poly(N-isopropylacrylamide) and Poly(Carboxylic Acid)– Iron Particles via Atom Transfer Radical Polymerization for Biomedical Applications

    Science.gov (United States)

    Sutrisno, Joko; Fuchs, Alan; Evrensel, Cahit

    2014-01-01

    This research relates to the preparation and characterization of surface grafted poly(N-isopropylacrylamide) and poly(carboxylic acid)–micron-size iron particles via atom transfer radical polymerization (ATRP). The surface grafted polymers–iron particles result in multifunctional materials which can be used in biomedical applications. The functionalities consist of cell targeting, imaging, drug delivery, and immunological response. The multifunctional materials are synthesized in two steps. First, surface grafting is used to place polymer molecules on the iron particles surface. The second step, is conjugation of the bio-molecules onto the polymer backbone. Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy were used to confirm the presence of polymers on the iron particles. The thickness of the grafted polymers and glass transition temperature of the surface grafted polymers were determined by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The covalent bond between grafted polymers and iron particles caused higher glass transition temperature as compared with non-grafted polymers. The ability to target the bio-molecule and provide fluorescent imaging was simulated by conjugation of rat immunoglobulin and fluorescein isothiocyanate (FITC) labeled anti-rat. The fluorescence intensity was determined using flow cytometry and conjugated IgG-FITC anti-rat on iron particles which was imaged using a fluorescence microscopy. PMID:25382869

  1. Grafting of Poly(methyl methacrylate Brushes from Magnetite Nanoparticles Using a Phosphonic Acid Based Initiator by Ambient Temperature Atom Transfer Radical Polymerization (ATATRP

    Directory of Open Access Journals (Sweden)

    Babu Kothandapani

    2008-01-01

    Full Text Available AbstractPoly(methyl methacrylate in the brush form is grown from the surface of magnetite nanoparticles by ambient temperature atom transfer radical polymerization (ATATRP using a phosphonic acid based initiator. The surface initiator was prepared by the reaction of ethylene glycol with 2-bromoisobutyrl bromide, followed by the reaction with phosphorus oxychloride and hydrolysis. This initiator is anchored to magnetite nanoparticles via physisorption. The ATATRP of methyl methacrylate was carried out in the presence of CuBr/PMDETA complex, without a sacrificial initiator, and the grafting density is found to be as high as 0.90 molecules/nm2. The organic–inorganic hybrid material thus prepared shows exceptional stability in organic solvents unlike unfunctionalized magnetite nanoparticles which tend to flocculate. The polymer brushes of various number average molecular weights were prepared and the molecular weight was determined using size exclusion chromatography, after degrafting the polymer from the magnetite core. Thermogravimetric analysis, X-ray photoelectron spectra and diffused reflection FT-IR were used to confirm the grafting reaction.

  2. Transient effects of 2,4-dichlorophenoxyacetic acid (2,4-D) exposure on some metabolic and free radical processes in goldfish white muscle.

    Science.gov (United States)

    Kubrak, Olga I; Atamaniuk, Tetiana M; Husak, Viktor V; Lushchak, Volodymyr I

    2013-09-01

    This study aims to assess effects of 96 h goldfish exposure to 1, 10 and 100 mg/L of the herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), on metabolic indices and free radical process markers in white muscle of a commercial fish, the goldfish Carassius auratus L. Most oxidative stress markers and antioxidant enzymes were not affected at 2,4-D fish treatment. 2,4-D fish exposure induced the elevated levels of total (by 46% and 40%) and reduced (by 77% and 73%) glutathione in muscles of goldfish of 10 mg/L 2,4-D and recovery (after 100 mg/L of 2,4-D exposure) groups, respectively. However, in muscles of 100 mg/L 2,4-D exposed goldfish these parameters were depleted (by 47% and 64%). None of investigated parameters of protein and carbohydrate metabolisms changed in white muscles of 2,4-D exposed fish, with exception of lactate dehydrogenase activity, which was slightly (by 11-15%) elevated in muscles of goldfish exposed to 10-100 mg/L of 2,4-D, but also recovered. Thus, the short term exposure of goldfish to the selected concentrations of 2,4-D does not substantially affect their white muscle, suggesting the absence of any effect under the environmentally relevant concentrations. PMID:23806294

  3. Oxidation of Gas-Phase SO2 on the Surfaces of Acidic Microdroplets: Implications for Sulfate and Sulfate Radical Anion Formation in the Atmospheric Liquid Phase.

    Science.gov (United States)

    Hung, Hui-Ming; Hoffmann, Michael R

    2015-12-01

    The oxidation of SO2(g) on the interfacial layers of microdroplet surfaces was investigated using a spray-chamber reactor coupled to an electrospray ionization mass spectrometer. Four major ions, HSO3(-), SO3(•-), SO4(•-) and HSO4(-), were observed as the SO2(g)/N2(g) gas-mixture was passed through a suspended microdroplet flow, where the residence time in the dynamic reaction zone was limited to a few hundred microseconds. The relatively high signal intensities of SO3(•-), SO4(•-), and HSO4(-) compared to those of HSO3(-) as observed at pH oxygen suggests an efficient oxidation pathway via sulfite and sulfate radical anions on droplets possibly via the direct interfacial electron transfer from HSO3(-) to O2. The concentrations of HSO3(-) in the aqueous aerosol as a function of pH were controlled by the deprotonation of hydrated sulfur dioxide, SO2·H2O, which is also affected by the pH dependent uptake coefficient. When H2O2(g) was introduced into the spray chamber simultaneously with SO2(g), HSO3(-) is rapidly oxidized to form bisulfate in the pH range of 3 to 5. Conversion to sulfate was less at pH reactions. The rapid oxidation of SO2(g) on the acidic microdroplets was estimated as 1.5 × 10(6) [S(IV)] (M s(-1)) at pH ? 3. In the presence of acidic aerosols, this oxidation rate is approximately 2 orders of magnitude higher than the rate of oxidation with H2O2(g) at a typical atmospheric H2O2(g) concentration of 1 ppb. This finding highlights the relative importance of the acidic surfaces for SO2 oxidation in the atmosphere. Surface chemical reactions on aquated aerosol surfaces, as observed in this study, are overlooked in most atmospheric chemistry models. These reaction pathways may contribute to the rapid production of sulfate aerosols that is often observed in regions impacted by acidic haze aerosol such as Beijing and other megacities around the world. PMID:26270804

  4. Radical-scavenging capacity of phenol fractions in the brown seaweed Ascophyllum nodosum: an electrochemical approach.

    Science.gov (United States)

    Blanc, Nathalie; Hauchard, Didier; Audibert, Laetitia; Gall, Erwan Ar

    2011-04-15

    In this article, the radical-scavenging capacity of phenol fractions extracted from the brown seaweed Ascophyllum nodosum was assessed using in parallel colorimetric methods (ABTS and DPPH) and electrochemistry (cyclic voltammetry). Results obtained by the three methods correlated in the case of global fractions, whereas only ABTS and DPPH correlated when activities were expressed on a phenol basis. The successive fractions separated by both their average molecular size and their polarity exhibited activities largely dependent on their phenol content, suggesting that phlorotannins are the main anti-oxidant molecules in hydro-alcoholic extracts of A. nodosum. In addition, phenol fractions of relative low molecular weight were clearly more active than others. This work opens new opportunities to better evaluate the radical-scavenging potential of phenol pools in algae using both bi-parametric fractionating and electrochemistry. PMID:21376981

  5. Hydrogen transfer between sulfuric acid and hydroxyl radical in the gas phase: competition among hydrogen atom transfer, proton-coupled electron-transfer, and double proton transfer.

    Science.gov (United States)

    Anglada, Josep M; Olivella, Santiago; Solé, Albert

    2006-02-01

    In an attempt to assess the potential role of the hydroxyl radical in the atmospheric degradation of sulfuric acid, the hydrogen transfer between H2SO4 and HO* in the gas phase has been investigated by means of DFT and quantum-mechanical electronic-structure calculations, as well as classical transition state theory computations. The first step of the H2SO4 + HO* reaction is the barrierless formation of a prereactive hydrogen-bonded complex (Cr1) lying 8.1 kcal mol(-1) below the sum of the (298 K) enthalpies of the reactants. After forming Cr1, a single hydrogen transfer from H2SO4 to HO* and a degenerate double hydrogen-exchange between H2SO4 and HO* may occur. The single hydrogen transfer, yielding HSO4* and H2O, can take place through three different transition structures, the two lowest energy ones (TS1 and TS2) corresponding to a proton-coupled electron-transfer mechanism, whereas the higher energy one (TS3) is associated with a hydrogen atom transfer mechanism. The double hydrogen-exchange, affording products identical to reactants, takes place through a transition structure (TS4) involving a double proton-transfer mechanism and is predicted to be the dominant pathway. A rate constant of 1.50 x 10(-14) cm(3) molecule(-1) s(-1) at 298 K is obtained for the overall reaction H2SO4 + HO*. The single hydrogen transfer through TS1, TS2, and TS3 contributes to the overall rate constant at 298 K with a 43.4%. It is concluded that the single hydrogen transfer from H2SO4 to HO* yielding HSO4* and H2O might well be a significant sink for gaseous sulfuric acid in the atmosphere. PMID:16451034

  6. In vitro antioxidant properties, free radicals scavenging activities of extracts and polyphenol composition of a non-timber forest product used as spice: Monodora myristica

    Directory of Open Access Journals (Sweden)

    Bruno Moukette Moukette

    2015-01-01

    Full Text Available BACKGROUND: Excessive production of free radicals causes direct damage to biological molecules such as DNA, proteins, lipids, carbohydrates leading to tumor development and progression. Natural antioxidant molecules from phytochemicals of plant origin may directly inhibit either their production or limit their propagation or destroy them to protect the system. In the present study, Monodora myristica a non-timber forest product consumed in Cameroon as spice was screened for its free radical scavenging properties, antioxidant and enzymes protective activities. Its phenolic compound profile was also realized by HPLC. RESULTS: This study demonstrated that M. myristica has scavenging properties against DPPH',OH',NO', and ABTS'radicals which vary in a dose depending manner. It also showed an antioxidant potential that was comparable with that of Butylated Hydroxytoluene (BHT and vitamin C used as standard. The aqueous ethanol extract of M. myristica barks (AEH; showed a significantly higher content in polyphenolic compounds (21.44 ±0.24 mg caffeic acid/g dried extract and flavonoid (5.69 ± 0.07 quercetin equivalent mg/g of dried weight as compared to the other studied extracts. The HPLC analysis of the barks and leaves revealed the presence of several polyphenols. The acids (3,4-OH-benzoic, caffeic, gallic, O- and P- coumaric, syringic, vanillic, alcohols (tyrosol and OH-tyrosol, theobromine, quercetin, rutin, catechine and apigenin were the identified and quantified polyphenols. All the tested extracts demonstrated a high protective potential on the superoxide dismutase (SOD, catalase and peroxidase activities. CONCLUSION: Finally, the different extracts from M. myristica and specifically the aqueous ethanol extract reveal several properties such as higher free radical scavenging properties, significant antioxidant capacities and protective potential effects on liver enzymes.

  7. In vitro antioxidant properties, free radicals scavenging activities of extracts and polyphenol composition of a non-timber forest product used as spice: Monodora myristica

    Scientific Electronic Library Online (English)

    Bruno Moukette, Moukette; Constant Anatole, Pieme; Jacques Romain, Njimou; Cabral Prosper Nya, Biapa; Bravi, Marco; Jeanne Yonkeu, Ngogang.

    Full Text Available BACKGROUND: Excessive production of free radicals causes direct damage to biological molecules such as DNA, proteins, lipids, carbohydrates leading to tumor development and progression. Natural antioxidant molecules from phytochemicals of plant origin may directly inhibit either their production or [...] limit their propagation or destroy them to protect the system. In the present study, Monodora myristica a non-timber forest product consumed in Cameroon as spice was screened for its free radical scavenging properties, antioxidant and enzymes protective activities. Its phenolic compound profile was also realized by HPLC. RESULTS: This study demonstrated that M. myristica has scavenging properties against DPPH',OH',NO', and ABTS'radicals which vary in a dose depending manner. It also showed an antioxidant potential that was comparable with that of Butylated Hydroxytoluene (BHT) and vitamin C used as standard. The aqueous ethanol extract of M. myristica barks (AEH); showed a significantly higher content in polyphenolic compounds (21.44 ±0.24 mg caffeic acid/g dried extract) and flavonoid (5.69 ± 0.07 quercetin equivalent mg/g of dried weight) as compared to the other studied extracts. The HPLC analysis of the barks and leaves revealed the presence of several polyphenols. The acids (3,4-OH-benzoic, caffeic, gallic, O- and P- coumaric, syringic, vanillic), alcohols (tyrosol and OH-tyrosol), theobromine, quercetin, rutin, catechine and apigenin were the identified and quantified polyphenols. All the tested extracts demonstrated a high protective potential on the superoxide dismutase (SOD), catalase and peroxidase activities. CONCLUSION: Finally, the different extracts from M. myristica and specifically the aqueous ethanol extract reveal several properties such as higher free radical scavenging properties, significant antioxidant capacities and protective potential effects on liver enzymes.

  8. Exploiting the synergy between carboplatin and ABT-737 in the treatment of ovarian carcinomas.

    KAUST Repository

    Jain, Harsh Vardhan

    2014-01-06

    Platinum drug-resistance in ovarian cancers mediated by anti-apoptotic proteins such as Bcl-xL is a major factor contributing to the chemotherapeutic resistance of recurrent disease. Consequently, concurrent inhibition of Bcl-xL in combination with chemotherapy may improve treatment outcomes for patients. Here, we develop a mathematical model to investigate the potential of combination therapy with ABT-737, a small molecule inhibitor of Bcl-xL, and carboplatin, a platinum-based drug, on a simulated tumor xenograft. The model is calibrated against in vivo experimental data, wherein xenografts established in mice were treated with ABT-737 and/or carboplatin on a fixed periodic schedule. The validated model is used to predict the minimum drug load that will achieve a predetermined level of tumor growth inhibition, thereby maximizing the synergy between the two drugs. Our simulations suggest that the infusion-duration of each carboplatin dose is a critical parameter, with an 8-hour infusion of carboplatin given weekly combined with a daily bolus dose of ABT-737 predicted to minimize residual disease. The potential of combination therapy to prevent or delay the onset of carboplatin-resistance is also investigated. When resistance is acquired as a result of aberrant DNA-damage repair in cells treated with carboplatin, drug delivery schedules that induce tumor remission with even low doses of combination therapy can be identified. Intrinsic resistance due to pre-existing cohorts of resistant cells precludes tumor regression, but dosing strategies that extend disease-free survival periods can still be identified. These results highlight the potential of our model to accelerate the development of novel therapeutics such as BH3 mimetics.

  9. ANTIOXIDANT CAPACITY AND AMINO ACID PROFILES OF EGG TOFU

    Directory of Open Access Journals (Sweden)

    Maizura Murad

    2013-01-01

    Full Text Available Tofu contains high quality protein source and antioxidant which could reduce risk of cancer. This research aims to determine the effect of soymilk and egg ratios on the antioxidant capacity, daidzein and genistein content and amino acid profiles of egg tofu. Egg tofu was prepared using soymilk and fresh egg in ratios of 1:1, 2:1, 3:1 and 4:1. Glucono-Delta-Lactone (GDL was added in the egg tofu to act as a coagulating agent. Increased of soymilk at all ratios had significantly (p<0.05 increased in Ferric-Reducing Antioxidant Power (FRAP, daidzein and genistein content of egg tofu. Conversely, decreased in soymilk ratio had significantly (p<0.05 increased the radical scavenging activities of the 2,2-Azino-Bis 3-ethylbenzothiazoline-6-Sulfonic acid (ABTS and 2,2-Diphenyl-2-Picrylhydrazyl (DPPH in egg tofu. Increased of soymilk ratio up to 3:1 caused decreased in amino acid methionine (met and cystein (cys significantly (p<0.05. A significant (p<0.01 and a positive correlation was observed between Total Phenolic Content (TPC and FRAP (r = 0.93. However, there was a negative (p<0.01 correlation between TPC and DPPH (r = -0.83. The antioxidant capacity of egg tofu in DPPH assay showed a positive and significant (p<0.01 correlation with cysteine, methionine and tryptophan with r value of 0.92, 0.93 and 0.96 respectively. Higher content of egg in egg tofu had contributed to the increased of antioxidant capacity as indicated in DPPH assay and ABTS assay as well as amino acid methionine and cysteine.

  10. The molecular basis of synergism between carboplatin and ABT-737 therapy targeting ovarian carcinomas.

    OpenAIRE

    Jain, Harsh Vardhan; Meyer-Hermann, Michael

    2011-01-01

    Resistance to standard chemotherapy (carboplatin + paclitaxel) is one of the leading causes of therapeutic failure in ovarian carcinomas. Emergence of chemoresistance has been shown to be mediated in part by members of the Bcl family of proteins including the antiapoptotic protein Bcl-x(L), whose expression is correlated with shorter disease-free intervals in recurrent disease. ABT-737 is an example of one of the first small-molecule inhibitors of Bcl-2/Bcl-x(L) that has been shown to increas...

  11. Exploiting the Synergy between Carboplatin and ABT-737 in the Treatment of Ovarian Carcinomas

    OpenAIRE

    Jain, Harsh Vardhan; Richardson, Alan; Meyer-Hermann, Michael; Helen M. Byrne

    2014-01-01

    Platinum drug-resistance in ovarian cancers mediated by anti-apoptotic proteins such as Bcl-xL is a major factor contributing to the chemotherapeutic resistance of recurrent disease. Consequently, concurrent inhibition of Bcl-xL in combination with chemotherapy may improve treatment outcomes for patients. Here, we develop a mathematical model to investigate the potential of combination therapy with ABT-737, a small molecule inhibitor of Bcl-xL, and carboplatin, a platinum-based drug, on a sim...

  12. A novel poly(ADP-ribose) polymerase inhibitor, ABT-888, radiosensitizes malignant human cell lines under hypoxia

    International Nuclear Information System (INIS)

    The chemo- and radioresponse of tumor cells can be determined by genetic factors (e.g., those that modify cell cycle arrest, DNA damage repair or cell death) and microenvironmental factors, such as hypoxia. Poly(ADP-ribose) polymerase (PARP) is a nuclear enzyme that rapidly recognizes and binds to DNA breaks to facilitate DNA strand break repair. Pre-clinical data suggest that PARP inhibitors (PARPi) may potentiate the effects of radiotherapy and chemotherapy. However, it is unclear as to whether PARPi are effective against hypoxic cells. We therefore tested the role for a novel PARPi, ABT-888, as a radiosensitizing agent under hypoxic conditions. Using human prostate (DU-145, 22RV1) and non-small cell lung (H1299) cancer cell lines, we observed that ABT-888 inhibited both recombinant PARP activity and intracellular PARP activity (86% to 92% decrease in all 3 cells lines following 2.5 ?M treatment). ABT-888 was toxic to both oxic and hypoxic cells. When ABT-888 was combined with ionizing radiation (IR), clonogenic radiation survival was decreased by 40-50% under oxic conditions. Under acute hypoxia, ABT-888 radiosensitized malignant cells to a level similar to oxic radiosensitivity. To our knowledge, this is the first study to demonstrate that inhibition of PARP activity can sensitize hypoxic cancer cells and the combination of IR-PARPi has the potential to improve the therapeutic ratio of radiotherapy

  13. Hydrophobic benzyl amines as supports for liquid-phase C-terminal amidated peptide synthesis: application to the preparation of ABT-510.

    Science.gov (United States)

    Matsumoto, Emiko; Fujita, Yuko; Okada, Yohei; Kauppinen, Esko I; Kamiya, Hidehiro; Chiba, Kazuhiro

    2015-09-01

    C-terminal amidation is one of the most common modification of peptides and frequently found in bioactive peptides. However, the C-terminal modification must be creative, because current chemical synthetic techniques of peptides are dominated by the use of C-terminal protecting supports. Therefore, it must be carried out after the removal of such supports, complicating reaction work-up and product isolation. In this context, hydrophobic benzyl amines were successfully added to the growing toolbox of soluble tag-assisted liquid-phase peptide synthesis as supports, leading to the total synthesis of ABT-510 (2). Although an ethyl amide-forming type was used in the present work, different types of hydrophobic benzyl amines could also be simply designed and prepared through versatile reductive aminations in one step. The standard acidic treatment used in the final deprotection step for peptide synthesis gave the desired C-terminal secondary amidated peptide with no epimerization. PMID:26200065

  14. Strong Inhibition of O-Atom Transfer Reactivity for Mn(IV)(O)(?-Radical-Cation)(Lewis Acid) versus Mn(V)(O) Porphyrinoid Complexes.

    Science.gov (United States)

    Zaragoza, Jan Paulo T; Baglia, Regina A; Siegler, Maxime A; Goldberg, David P

    2015-05-27

    The oxygen atom transfer (OAT) reactivity of two valence tautomers of a Mn(V)(O) porphyrinoid complex was compared. The OAT kinetics of Mn(V)(O)(TBP8Cz) (TBP8Cz = octakis(p-tert-butylphenyl)corrolazinato(3-)) reacting with a series of triarylphosphine (PAr3) substrates were monitored by stopped-flow UV-vis spectroscopy, and revealed second-order rate constants ranging from 16(1) to 1.43(6) × 10(4) M(-1) s(-1). Characterization of the OAT transition state analogues Mn(III)(OPPh3)(TBP8Cz) and Mn(III)(OP(o-tolyl)3)(TBP8Cz) was carried out by single-crystal X-ray diffraction (XRD). A valence tautomer of the closed-shell Mn(V)(O)(TBP8Cz) can be stabilized by the addition of Lewis and Brønsted acids, resulting in the open-shell Mn(IV)(O)(TBP8Cz(•+)):LA (LA = Zn(II), B(C6F5)3, H(+)) complexes. These Mn(IV)(O)(?-radical-cation) derivatives exhibit dramatically inhibited rates of OAT with the PAr3 substrates (k = 8.5(2) × 10(-3) - 8.7 M(-1) s(-1)), contrasting the previously observed rate increase of H-atom transfer (HAT) for Mn(IV)(O)(TBP8Cz(•+)):LA with phenols. A Hammett analysis showed that the OAT reactivity for Mn(IV)(O)(TBP8Cz(•+)):LA is influenced by the Lewis acid strength. Spectral redox titration of Mn(IV)(O)(TBP8Cz(•+)):Zn(II) gives Ered = 0.69 V vs SCE, which is nearly +700 mV above its valence tautomer Mn(V)(O)(TBP8Cz) (Ered = -0.05 V). These data suggest that the two-electron electrophilicity of the Mn(O) valence tautomers dominate OAT reactivity and do not follow the trend in one-electron redox potentials, which appear to dominate HAT reactivity. This study provides new fundamental insights regarding the relative OAT and HAT reactivity of valence tautomers such as M(V)(O)(porph) versus M(IV)(O)(porph(•+)) (M = Mn or Fe) found in heme enzymes. PMID:25964988

  15. Anticancer compound ABT-263 accelerates apoptosis in virus-infected cells and imbalances cytokine production and lowers survival rates of infected mice

    OpenAIRE

    Kakkola, L; Denisova, O V; Tynell, J; Viiliäinen, J; Ysenbaert, T; Matos, R C; Nagaraj, A; Öhman, T; Kuivanen, S; Paavilainen, H; Feng, L; Yadav, B; Julkunen, I; Vapalahti, O.; Hukkanen, V

    2013-01-01

    ABT-263 and its structural analogues ABT-199 and ABT-737 inhibit B-cell lymphoma 2 (Bcl-2), BCL2L1 long isoform (Bcl-xL) and BCL2L2 (Bcl-w) proteins and promote cancer cell death. Here, we show that at non-cytotoxic concentrations, these small molecules accelerate the deaths of non-cancerous cells infected with influenza A virus (IAV) or other viruses. In particular, we demonstrate that ABT-263 altered Bcl-xL interactions with Bcl-2 antagonist of cell death (Bad), Bcl-2-associated X protein (...

  16. Chemical Constituents with Free-Radical-Scavenging Activities from the Stem of Microcos paniculata

    OpenAIRE

    Yu Chen; Xiang-Ming Liu; Tong Zheng; Zhi-Nan Mei; Guang-Zhong Yang; Su Chen; Hua Fan

    2010-01-01

    The free-radical-scavenging activities of various solvent extracts of Microcos paniculata were evaluated through in vitro model systems, such as 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) and Co (II) EDTA-induced luminol chemiluminescence by flow injection. In all three of these systems the ethyl acetate (EtOAc) extract showed the highest free-radical-scavenging activity compared with the other three (n-BuOH, water and petroleum ether) ext...

  17. Reaction between protein radicals and other biomolecules

    DEFF Research Database (Denmark)

    Østdal, Henrik; Davies, Michael Jonathan

    2002-01-01

    The present study investigates the reactivity of bovine serum albumin (BSA) radicals towards different biomolecules (urate, linoleic acid, and a polypeptide, poly(Glu-Ala-Tyr)). The BSA radical was formed at room temperature through a direct protein-to-protein radical transfer from H(2)O(2)-activated immobilized horseradish peroxidase (im-HRP). Subsequently, each of the three different biomolecules was separately added to the BSA radicals, after removal of im-HRP by centrifugation. Electron spin resonance (ESR) spectroscopy showed that all three biomolecules quenched the BSA radicals. Subsequent analysis showed a decrease in the concentration of urate upon reaction with the BSA radical, while the BSA radical in the presence of poly(Glu-Ala-Tyr) resulted in increased formation of the characteristic protein oxidation product, dityrosine. Reaction between the BSA radical and a linoleic acid oil-in-water emulsion resulted in additional formation of lipid hydroperoxides and conjugated dienes. The results clearly show that protein radicals have to be considered as dynamic species during oxidative processes in biological systems and that protein radicals should not be considered as end-products, but rather as reactive intermediates during oxidative processes in biological systems hereby supporting recent data.

  18. A hydrogen-donating monohydroxamate scavenges ferryl myoglobin radicals

    DEFF Research Database (Denmark)

    Cooper, C E; Green, E S; Rice-Evans, C A; Davies, M J; Wrigglesworth, J M

    1994-01-01

    -lived radical is observed at lower concentrations that is still present after 90 minutes. The monohydroxamate N-methylbutyro-hydroxamic acid (NMBH) increases the rate of decay of the fenyl species. In the presence of NMBH, none of the protein-bound free radicals are detectable; instead nitroxide radicals...

  19. Antioxidant activities and radical scavenging activities of flavonoids studied by the electrochemical methods and ESR technique based on the novel paramagnetic properties of poly(aniline-co-5-aminosalicylic acid)

    International Nuclear Information System (INIS)

    Graphical abstract: ESR spectra of the PAASA/RGO/graphite electrodes: (1) in the buffer solution consisting of 0.20 M phosphate and methanol (80: 20, v/v), (2) in the buffer solutions containing 150 μM of (+)-catechin. -- Abstract: Four kinds of flavonoid, viz. flavanone naringenin, Flavone apigenin, flavonol kaempferol, and flavanol (+)-catechin, are used to investigate their antioxidant and radical scavenging activitis in the water-methanol solution of pH 6.3, using the electrochemical methods and electron spin resonance (ESR) technique. Poly(aniline-co-5-aminosalicylic acid) (PAASA) is first used as a radical source that was polymerized on a reduced graphene oxide (RGO)/glassy carbon (GC) disk or on the RGO/graphite fiber electrode. The assessment of the antioxidant activities is performed using both cyclic voltammetry and the open circuit potential measurement. On the basis of results from both electrochemical mathods, the order of the antioxidant actitvities of flavonoids is as follows: (+)-catechin > kaempferol > apigenin > naringenin However, the difference in the antioxidant activities between naringenin and apigenin is very small. On the basis of the ESR signal intensities of PAASA, the order of the radical scavenging activities of flavonoids is in good agreement with that of the above antioxdant activities.Three oxidation peaks on the cyclic voltammograms of (+)-catechin are first detected, which gives us a deep insight into the oxidation mechanism of (+)-catechin

  20. In vitro antioxidant potential and deoxyribonucleic acid protecting activity of CNB-001, a novel pyrazole derivative of curcumin

    Directory of Open Access Journals (Sweden)

    Richard L Jayaraj

    2014-01-01

    Full Text Available Background: Free radicals are underpinned to initiate cascade of toxic events leading to oxidative stress and resultant cell death in many neurodegenerative disorders. Now-a-days antioxidants have become mandatory in the treatment of various diseases apart from the drug?s modes of action. CNB-001, a novel hybrid molecule synthesized by combining curcumin and cyclohexyl bisphenol A is known to possess various biological activities, but the antioxidative property of the compound has not yet been elucidated. Aim: The present study is aimed to analyze various free radicals scavenging by employing in vitro antioxidant assays and to evaluate the deoxyribonucleic acid (DNA protecting the ability of CNB-001 against hydroxyl radicals. Materials and methods: The in vitro antioxidant potential of CNB-001 was evaluated by analyzing its ability to scavenge DPPH, ABTS, nitric oxide, superoxide, hydrogen peroxide, superoxide anion, hydroxyl, hydrogen peroxide radicals and reducing power using spectroscopic method. The DNA protecting activity of CNB-001 was also evaluated on pUC19 plasmid DNA subjected to hydroxyl radicals using standard agarose gel electrophoresis. Results: From the assays, it was observed that CNB-001 scavenged free radicals effectively in a dose dependent manner. CNB-001 scavenged 2,2-diphenyl-1-picrylhydrazyl (IC50 = 44.99 ?g/ml, 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid (IC50 = 17.99 ?g/ml, nitric oxide (IC50 = 1.36 ?g/ml, superoxide radical (IC50 = 77.17 ?g/ml, hydrogen peroxide (IC50 = 492.7 ?g/ml, superoxide (IC50 = 36.92 ?g/ml and hydroxyl (IC50 = 456.5 ?g/ml radicals effectively and the reducing power was found to be 11.53 ?g/ml. CNB-001 showed considerable protecting activity against plasmid DNA (pUC19 strand scission by ·OH at dose dependent manner. Conclusion: Results from these assays concluded that CNB-001 has a good antioxidant potential by reducing reactive oxygen and reactive nitrogen radicals and it showed significant protecting activity against DNA scission by hydroxyl radicals. Hence, CNB-001 can be further developed as potential drug for free radical induced neurodegenerative disorders.

  1. Melanin and humic acid-like polymer complex from olive mill waste waters. Part I. Isolation and characterization.

    Science.gov (United States)

    Khemakhem, Maissa; Papadimitriou, Vassiliki; Sotiroudis, Georgios; Zoumpoulakis, Panagiotis; Arbez-Gindre, Cécile; Bouzouita, Nabiha; Sotiroudis, Theodore G

    2016-07-15

    A water soluble humic acid and melanin-like polymer complex (OMWW-ASP) was isolated from olive mill waste waters (OMWW) by ammonium sulfate fractionation to be used as natural additive in food preparations. The dark polymer complex was further characterized by a variety of biochemical, physicochemical and spectroscopic techniques. OMWW-ASP is composed mainly of proteins associated with polyphenols and carbohydrates and the distribution of its relative molecular size was determined between about 5 and 190kDa. SDS-PAGE shows the presence of a well separated protein band of 21.3kDa and a low molecular weight peptide. The OMWW-ASP complex exhibits a monotonically increasing UV-Vis absorption spectrum and it contains stable radicals. Antioxidant activity measurements reveal the ability of the OMWW protein fraction to scavenge both the cationic 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS(+)) radical, as well as the stable nitroxide free radical 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPOL). PMID:26948649

  2. Mathematical Evaluation of the Amino Acid and Polyphenol Content and Antioxidant Activities of Fruits from Different Apricot Cultivars

    Directory of Open Access Journals (Sweden)

    Rene Kizek

    2011-09-01

    Full Text Available Functional foods are of interest because of their significant effects on human health, which can be connected with the presence of some biologically important compounds. In this study, we carried out complex analysis of 239 apricot cultivars (Prunus armeniaca L. cultivated in Lednice (climatic area T4, South Moravia, Czech Republic. Almost all previously published studies have focused only on analysis of certain parameters. However, we focused on detection both primary and secondary metabolites in a selection of apricot cultivars with respect to their biological activity. The contents of thirteen biogenic alpha-L-amino acids (arginine, asparagine, isoleucine, lysine, serine, threonine, valine, leucine, phenylalanine, tryptophan, tyrosine, proline and alanine were determined using ion exchange chromatography with UV-Vis spectrometry detection. Profile of polyphenols, measured as content of ten polyphenols with significant antioxidant properties (gallic acid, procatechinic acid, p-aminobenzoic acid, chlorogenic acid, caffeic acid, vanillin, p-coumaric acid, rutin, ferrulic acid and quercetrin, was determined by high performance liquid chromatography with spectrometric/electrochemical detection. Moreover, content of total phenolics was determined spectrophotometrically using the Folin-Ciocalteu method. Antioxidant activity was determined using five independent spectrophotometric methods: DPPH assay, DMPD method, ABTS method, FRAP and Free Radicals methods. Considering the complexity of the obtained data, they were processed and correlated using bioinformatics techniques (cluster analysis, principal component analysis. The studied apricot cultivars were clustered according to their common biochemical properties, which has not been done before. The observed similarities and differences were discussed.

  3. A radical approach to radical innovation

    OpenAIRE

    Deichmann, Dirk; Ende, Jan van der

    2014-01-01

    Innovation pays. Amazon, Apple, Facebook, Google – nearly every one of today’s most successful companies has a talent for developing radical new ideas. But how best to encourage radical initiative taking from employees, and does their previous success or failure at it play a role?

  4. Emergence of oxyl radicals as selective oxidants.

    Science.gov (United States)

    Ramasarma, T

    2012-10-01

    Hydroxyl radicals (HO*) are derived in Fenton reaction with ferrous salt and H2O2 in acid medium, and at neutral pH, metal-oxyl radicals (M-O*) predominate. Evidence is accumulating that M-O* radicals are also active in oxidation reactions, in addition to metal-oxo (M=O) now shown in many publications. Reactivity of these radicals gives selective oxidized products useful in cellular activities, in contrast to purported indiscriminate cell damage by hydroxyl radicals. Reactions with vanadium compounds, such as diperoxovanadate, peroxo-bridged mixed valency divanadate, vanadium-oxyl radical, tetravalent vanadyl and decavanadate illustrates selective gain in oxidative capacity of oxo- and oxyl- species. Occurrence of ESR signals typical of hydroxyl radicals is demonstrated in cell homogenates and tissue perfusates treated with spin trap agents. It is known for a long time lipid peroxides are formed in tissue microsomal systems exclusively in presence of salts of iron, among many metals tested. Oxygen and a reducing agent, ascorbate (non-enzymic) or NADPH (enzymic) are required to produce 'ferryl', the chelated Fe=O active form (possibly Fe-O* and Fe-O-O-Fe ?) for the crucial step of H-atom abstraction. Yet literature is replete with unsupported affirmations that hydroxyl radicals initiate lipid peroxidation, an unexplained fixation of mindset. The best-known *OH generator, a mixture of ferrous salt and H2O2, does not promote lipid peroxidation, nor do the many hydroxyl radical quenching agents stop it. The availability of oxo and oxyl-radical forms with transition metals, and also with non metals, P, S, N and V, calls for expansion of vision beyond superoxide and hydroxyl radicals and explore functions of multiple oxygen radicals for their biological relevance. PMID:23259316

  5. Contemporary Radical Prostatectomy

    OpenAIRE

    Leon Sun; Qiang Fu; Judd W. Moul

    2011-01-01

    Purpose. Patients diagnosed with clinically localized prostate cancer have more surgical treatment options than in the past. This paper focuses on the procedures' oncological or functional outcomes and perioperative morbidities of radical retropubic prostatectomy, radical perineal prostatectomy, and robotic-assisted laparoscopic radical prostatectomy. Materials and Methods. A MEDLINE/PubMed search of the literature on radical prostatectomy and other new management options was performed. Resul...

  6. Hydroxyl radical detection in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Chevion, M.; Floyd, R.A.

    1986-05-01

    Hydroxyl radicals have been implicated as the actual species responsible for the deleterious effects of active oxygen in biology. However, in most cases, its presence has only been inferred by circumstantial evidence. Using electrochemical detection coupled to HPLC separation technique the authors can identify and quantitate (at sub-picomole level) the hydroxylated products of 3 aromatic compounds (phenol, salicylate, and 2-deoxy-guanosine) as a direct measure of hydroxyl radical formation. Firstly, the authors showed that mixing ascorbate with copper ions (in the absence of presence of a protein) yields catechols, dihydroxybenzoic acids and 8-OH-deoxy-guanosine (8-OHdG). This approach has been used to study the formation of OH in vivo. Human granulocytes stimulated with TPA showed that 8-OHdG was formed in the cellular DNA at high levels (one 8-OHdG/800 DNA bases). Unstimulated granulocytes contained 8-OHdG below detection level. Formation of 8-OHdG in the TPA-stimulated granulocytes DNA was decreased by the addition of SOD and catalase. Using salicylate as an in vivo scavenger of hydroxyl radicals the authors showed that the level of trapped-dihydroxybenzoic acids is increased approx.8 and approx.3 fold in the lungs and liver of paraquat-poisoned mice, respectively, as compared to normal animals. Similarly, the detected level of dihydroxybenzoic acids in the hearts of adriamycin-treated rats was increased over 100-fold as compared to the hearts of control animals.

  7. In vitro reduction of coplanar PCB congeners by ABTS oxidases from the culture of Trametes versicolor

    Energy Technology Data Exchange (ETDEWEB)

    Sonoki, S. [High-Tech Research Center, Azabu Univ., Kanagawa (Japan); Sue, T.; Hisamatsu, S. [Graduate School of Environmental Health, Azabu Univ., Kanagawa (Japan); Nagasaka, H. [Inst. of Environmental Ecology, Shin-Nippon Meteorological and Oceanographical Consultant Co., Ltd., Shizuoka (Japan)

    2004-09-15

    In recent years, the environmental contamination by the harmful polluted chemicals becomes more serious. Among them, especially, the dioxins such as coplanar PCBs (Co-PCBs) and PCDDs are hard to be decomposed due to their stability and hydrophobic nature, leading to the world-wide contamination. To clean up the polluted environment, bioremediation using a microorganism is expected to solve the environmental pollution problem because of cost-effective alternative to the more established engineering method. There are some reports on the biodegradation of dioxins using various organisms, in which basidiomycetes, so-called white-rot fungi, have been extensively studied in the process of lignin degradation. As a result unique extracellular oxidative lignindegrading enzymes, such as lignin peroxidase, manganese-dependent peroxidase and laccase were supposed to be responsible for degrading dioxins. Overall many studies on biodegradation of dioxins or other chlorinated aromatic hydrocarbons have focused on using white-rot fungi; however, few reports referred to the metabolism of these environmental pollutants in the in vitro reaction by use of lignin-degrading enzymes produced by white-rot fungi. In this study, we reported the reduction of levels of Co-PCBs in the in vitro incubation with the fractions which had the oxidase activity toward 2, 2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) in the culture fluid of white-rot fungus, Trametes versicolor.

  8. In Vitro Activity of ABT-773 against Legionella pneumophila, Its Pharmacokinetics in Guinea Pigs, and Its Use to Treat Guinea Pigs with L. pneumophila Pneumonia

    OpenAIRE

    Edelstein, Paul H; F. Higa; Edelstein, Martha A. C.

    2001-01-01

    The activity of ABT-773 was studied against extracellular and intracellular Legionella pneumophila and for the treatment of guinea pigs with L. pneumophila pneumonia. The ABT-773 MIC at which 50% of isolates are inhibited (MIC50) for 20 different Legionella sp. strains was 0.016 ?g/ml, whereas the MIC50s of clarithromycin and erythromycin were 0.032 and 0.125 ?g/ml, respectively. ABT-773 (1 ?g/ml) was bactericidal for two L. pneumophila strains grown in guinea pig alveolar macrophages. In con...

  9. Melatonin's unique radical scavenging properties - roles of its functional substituents as revealed by a comparison with its structural analogs.

    Science.gov (United States)

    Poeggeler, Burkhard; Thuermann, Sandra; Dose, Andreas; Schoenke, Markus; Burkhardt, Susanne; Hardeland, Rüdiger

    2002-08-01

    Melatonin's O-methyl and N-acetyl residues are not only the basis of its amphilicity enabling the molecule to enter all organs and all subcellular compartments, but are also decisive for its antioxidant properties. We have compared melatonin's redox chemistry with that of several structural analogs: tryptamine, N-acetyltryptamine, serotonin, N-acetylserotonin, 5-methoxytryptamine, 6-chloromelatonin and 2-iodomelatonin. Scavenging of hydroxyl radicals (*OH) was measured in a scavenger competition assay based on ABTS cation radical (ABTS(*)+) formation. The capability of undergoing single-electron transfer reactions was studied using an ABTS(*)+ reduction assay, reflecting the more general property of scavenging organic cation radicals. Direct scavenging of superoxide anions (O2(*)-), under non-catalyzed conditions, was investigated in a hematoxylin autoxidation assay. Measurements of chemiluminescence were used for studying scavenging of O2(*)- under catalyzed conditions, either by hemin-mediated interaction or by combination with the respective indolyl cation radicals. Light emission was determined in the absence or presence of the *OH scavenger dimethylsulfoxide and the O2(*)- scavenger Tiron. Products formed by oxidation of the respective indoles in a moderately alkaline, hemin-catalyzed H2O2 system were analyzed by thin-layer chromatography and fluorometry. Absence of either the O-methyl or the N-acetyl residue causes marked diminutions in the capacities of scavenging *OH and ABTS(*)+ as well as in chemiluminescence emitted during oxidation. The importance of the N-acetyl group is insofar remarkable as it seems, at first glance, to be isolated from the indolic moiety; interactions between side chain and indolic moiety are therefore decisive for melatonin's redox properties. The 5-hydroxylated compounds are not generally more efficient scavengers, but particularly better reducers of ABTS(*)+; in the alkaline H2O2 system generating *OH and O2(*)-, melatonin was much more rapidly oxidized than the 5-hydroxylated and non-substituted analogs. Oxidative products formed from any of the compounds studied contained much less of substituted kynuramines as in the case of melatonin, indicating that radical chain termination by O2(*)- is considerably more efficient with melatonin. These findings are supported by measurements of chemiluminescence, which largely reflects pyrrole ring cleavage as a result of combination with superoxide anions. In this regard, only 6-chloromelatonin equalled melatonin, whereas the efficiency of 2-iodomelatonin was much lower, another indication for the importance of 2,3-dioxygenation. PMID:12121482

  10. Free-radical inactivation of muscle aldolase

    International Nuclear Information System (INIS)

    Rabbit muscle aldolase has been shown to be deactivated by addition of irradiated crystals of various sugars and amino acids. Inactivation observed immediately upon dissolution is ascribed to reaction with free radicals, whereas post-dissolution inactivation is ascribed to acid-catalyzed reaction with nonradical radiolysis products. (U.S.)

  11. Comparison of In Vitro Activities of ABT-773 and Telithromycin against Macrolide-Susceptible and -Resistant Streptococci and Staphylococci

    OpenAIRE

    Shortridge, Virginia D.; Zhong, Ping; Cao, ZhenSheng; Beyer, Jill M.; Almer, Laurel S.; Ramer, Nancy C.; Doktor, Stella Z.; Flamm, Robert K.

    2002-01-01

    The activity of a new ketolide, ABT-773, was compared to the activity of the ketolide telithromycin (HMR-3647) against over 600 gram-positive clinical isolates, including 356 Streptococcus pneumoniae, 167 Staphylococcus aureus, and 136 Streptococcus pyogenes isolates. Macrolide-susceptible isolates as well as macrolide-resistant isolates with ribosomal methylase (Erm), macrolide efflux (Mef), and ribosomal mutations were tested using the NCCLS reference broth microdilution method. Both compou...

  12. Radical theory of rings

    CERN Document Server

    Gardner, JW

    2003-01-01

    Radical Theory of Rings distills the most noteworthy present-day theoretical topics, gives a unified account of the classical structure theorems for rings, and deepens understanding of key aspects of ring theory via ring and radical constructions. Assimilating radical theory's evolution in the decades since the last major work on rings and radicals was published, the authors deal with some distinctive features of the radical theory of nonassociative rings, associative rings with involution, and near-rings. Written in clear algebraic terms by globally acknowledged authorities, the presentation

  13. Reactions of carbonate radical with cobalt(II) aminopolycarboxylates

    International Nuclear Information System (INIS)

    Reactions of carbonate (CO3-radical) and bicarbonate (HCO3radical) radicals generated by photolysis of a carbonate or bicarbonate solution at pH 11.2 and 8.5, respectively, with Co(II) complexes of iminodiacetic acid (IDA) and ethylenediaminetetraacetic acid (EDTA) have been studied. The rate constants for the reactions were in the order of 106-107 dm3mol-1s-1. From the time-resolved spectroscopy of the products formed after reaction of CO3-radical or HCO3radical, it is observed that CO3-radical or HCO3radical oxidize the metal center to its higher oxidation state. (author) 26 refs.; 2 figs.; 1 tab

  14. In Vitro Activities of a New Ketolide, ABT-773, Alone and in Combination with Amoxicillin, Metronidazole, or Tetracycline against Helicobacter pylori

    OpenAIRE

    Pendland, Susan L.; Prause, Jennifer L.; Neuhauser, Melinda M.; Boyea, Nicole; Hackleman, Jodi M.; Danziger, Larry H.

    2000-01-01

    The in vitro activity of ABT-773, a new ketolide, was compared with those of clarithromycin, amoxicillin, metronidazole, and tetracycline against 15 strains of Helicobacter pylori. The MIC of ABT-773 at which 90% of isolates were inhibited was 0.25 ?g/ml, which was 3 dilutions higher than that of the most active agent, clarithromycin. Synergy and antagonism were not seen with any combinations. Additive activity was seen with tetracycline, metronidazole, and amoxicillin in 100, 60, and 40% of ...

  15. Effect of Bucillamine on Free-Radical-Mediated Degradation of High-Molar-Mass Hyaluronan Induced in vitro by Ascorbic Acid and Cu(II Ions

    Directory of Open Access Journals (Sweden)

    Mária Ba?asová

    2014-10-01

    Full Text Available The bucillamine effect on free-radical-mediated degradation of high-molar-mass hyaluronan (HA has been elucidated. As HA fragmentation is expected to decrease its dynamic viscosity, rotational viscometry was applied to follow the oxidative HA degradation. Non-isothermal chemiluminometry, thermogravimetry, differential scanning calorimetry, and size-exclusion chromatography (SEC were applied to characterize resulting HA fragments. Although bucillamine completely inhibited the HA viscosity decrease caused by oxidative system, indicating HA protection from degradation, SEC analysis suggested that some other mechanisms leading to the bucillamine transformations without the decay of the viscosity may come into a play as well. Nonetheless, the link between the reduction of chemiluminescence intensity and disappearance of the differential scanning calorimetry exotherm at 270 °C for fragmented HAs indicates a particular role of the bucillamine in preventing the decrease of HA viscosity.

  16. In Vitro Antioxidant Activities, Free Radical Scavenging Capacity, and Tyrosinase Inhibitory of Flavonoid Compounds and Ferulic Acid from Spiranthes sinensis (Pers.) Ames

    OpenAIRE

    Chung Pin Liang; Chia Hao Chang; Chien Cheng Liang; Kuei Yu Hung; Chang Wei Hsieh

    2014-01-01

    In this study, ultrasound-assisted extraction (UAE) and other methods of extracting flavonoid compounds and ferulic acid (FA) from S. sinensis were investigated. Five different extraction methods, including water extraction (W), water extraction using UAE (W+U), 75% ethanol extraction (E), 75% ethanol extraction using UAE (E+U), and supercritical CO2 extraction (SFE) were applied in the extraction of bioactive compounds (flavonoids and ferulic acid) in order to compare their efficiency. The h...

  17. Chemotherapeutic drugs sensitize human renal cell carcinoma cells to ABT-737 by a mechanism involving the Noxa-dependent inactivation of Mcl-1 or A1

    Directory of Open Access Journals (Sweden)

    Zantl Niko

    2010-06-01

    Full Text Available Abstract Background Human renal cell carcinoma (RCC is very resistant to chemotherapy. ABT-737 is a novel inhibitor of anti-apoptotic proteins of the Bcl-2 family that has shown promise in various preclinical tumour models. Results We here report a strong over-additive pro-apoptotic effect of ABT-737 and etoposide, vinblastine or paclitaxel but not 5-fluorouracil in cell lines from human RCC. ABT-737 showed very little activity as a single agent but killed RCC cells potently when anti-apoptotic Mcl-1 or, unexpectedly, A1 was targeted by RNAi. This potent augmentation required endogenous Noxa protein since RNAi directed against Noxa but not against Bim or Puma reduced apoptosis induction by the combination of ABT-737 and etoposide or vinblastine. At the level of mitochondria, etoposide-treatment had a similar sensitizing activity and allowed for ABT-737-induced release of cytochrome c. Conclusions Chemotherapeutic drugs can overcome protection afforded by Mcl-1 and A1 through endogenous Noxa protein in RCC cells, and the combination of such drugs with ABT-737 may be a promising strategy in RCC. Strikingly, A1 emerged in RCC cell lines as a protein of similar importance as the well-established Mcl-1 in protection against apoptosis in these cells.

  18. Potent and selective small-molecule MCL-1 inhibitors demonstrate on-target cancer cell killing activity as single agents and in combination with ABT-263 (navitoclax)

    Science.gov (United States)

    Leverson, J D; Zhang, H; Chen, J; Tahir, S K; Phillips, D C; Xue, J; Nimmer, P; Jin, S; Smith, M; Xiao, Y; Kovar, P; Tanaka, A; Bruncko, M; Sheppard, G S; Wang, L; Gierke, S; Kategaya, L; Anderson, D J; Wong, C; Eastham-Anderson, J; Ludlam, M J C; Sampath, D; Fairbrother, W J; Wertz, I; Rosenberg, S H; Tse, C; Elmore, S W; Souers, A J

    2015-01-01

    The anti-apoptotic protein MCL-1 is a key regulator of cancer cell survival and a known resistance factor for small-molecule BCL-2 family inhibitors such as ABT-263 (navitoclax), making it an attractive therapeutic target. However, directly inhibiting this target requires the disruption of high-affinity protein–protein interactions, and therefore designing small molecules potent enough to inhibit MCL-1 in cells has proven extremely challenging. Here, we describe a series of indole-2-carboxylic acids, exemplified by the compound A-1210477, that bind to MCL-1 selectively and with sufficient affinity to disrupt MCL-1–BIM complexes in living cells. A-1210477 induces the hallmarks of intrinsic apoptosis and demonstrates single agent killing of multiple myeloma and non-small cell lung cancer cell lines demonstrated to be MCL-1 dependent by BH3 profiling or siRNA rescue experiments. As predicted, A-1210477 synergizes with the BCL-2/BCL-XL inhibitor navitoclax to kill a variety of cancer cell lines. This work represents the first description of small-molecule MCL-1 inhibitors with sufficient potency to induce clear on-target cellular activity. It also demonstrates the utility of these molecules as chemical tools for dissecting the basic biology of MCL-1 and the promise of small-molecule MCL-1 inhibitors as potential therapeutics for the treatment of cancer. PMID:25590800

  19. Potent and selective small-molecule MCL-1 inhibitors demonstrate on-target cancer cell killing activity as single agents and in combination with ABT-263 (navitoclax).

    Science.gov (United States)

    Leverson, J D; Zhang, H; Chen, J; Tahir, S K; Phillips, D C; Xue, J; Nimmer, P; Jin, S; Smith, M; Xiao, Y; Kovar, P; Tanaka, A; Bruncko, M; Sheppard, G S; Wang, L; Gierke, S; Kategaya, L; Anderson, D J; Wong, C; Eastham-Anderson, J; Ludlam, M J C; Sampath, D; Fairbrother, W J; Wertz, I; Rosenberg, S H; Tse, C; Elmore, S W; Souers, A J

    2015-01-01

    The anti-apoptotic protein MCL-1 is a key regulator of cancer cell survival and a known resistance factor for small-molecule BCL-2 family inhibitors such as ABT-263 (navitoclax), making it an attractive therapeutic target. However, directly inhibiting this target requires the disruption of high-affinity protein-protein interactions, and therefore designing small molecules potent enough to inhibit MCL-1 in cells has proven extremely challenging. Here, we describe a series of indole-2-carboxylic acids, exemplified by the compound A-1210477, that bind to MCL-1 selectively and with sufficient affinity to disrupt MCL-1-BIM complexes in living cells. A-1210477 induces the hallmarks of intrinsic apoptosis and demonstrates single agent killing of multiple myeloma and non-small cell lung cancer cell lines demonstrated to be MCL-1 dependent by BH3 profiling or siRNA rescue experiments. As predicted, A-1210477 synergizes with the BCL-2/BCL-XL inhibitor navitoclax to kill a variety of cancer cell lines. This work represents the first description of small-molecule MCL-1 inhibitors with sufficient potency to induce clear on-target cellular activity. It also demonstrates the utility of these molecules as chemical tools for dissecting the basic biology of MCL-1 and the promise of small-molecule MCL-1 inhibitors as potential therapeutics for the treatment of cancer. PMID:25590800

  20. Radical Perineal Prostatectomy

    Directory of Open Access Journals (Sweden)

    Cemal Gökta?

    2015-12-01

    Full Text Available Prostate cancer is the most common malignancy and the second leading cause of cancer death in men. Complete surgical removal of the prostate is the most commonly used treatment option for patients with localized prostate cancer. Surgical treatment of localized prostate cancer includes radical retropubic prostatectomy, radical perineal prostatectomy and robotic/ laparoscopic radical prostatectomy. Since lympadenectomy from the same incision is not possible in radical retropubic prostatectomy, this approach is less preferable. On the other hand, when radical perineal prostatectomy in well selected cases is compared with radical retropubic prostatectomy in terms of many operational or functional criteria, similar results were obtained. In this paper, we aimed to report our experiences with this uncommon surgical approach.

  1. Characterization of pH-responsive hydrogels of poly(itaconic acid-g-ethylene glycol) prepared by UV-initiated free radical polymerization as biomaterials for oral delivery of bioactive agents.

    Science.gov (United States)

    Betancourt, Tania; Pardo, Juan; Soo, Ken; Peppas, Nicholas A

    2010-04-01

    Effective oral delivery of proteins is impeded by steep pH gradients and proteolytic enzymes in the gastrointestinal tract, as well as low absorption of the proteins into the bloodstream because of their size, charge, or solubility. In this work, pH-responsive complexation hydrogels of poly(itaconic acid) (PIA) with poly(ethylene glycol) (PEG) grafts were synthesized for applications in oral drug delivery. These hydrogels were expected to be in collapsed configuration at low pH because of hydrogen bonding between PIA carboxyl groups and PEG, and to swell with increasing pH because of charge repulsion between deprotonated carboxylic acid groups. Hydrogels were prepared by UV-initiated free radical polymerization using tetraethylene glycol as the crosslinking agent and Irgacure 2959 as the initiator. The effect of monomer ratios, crosslinking ratio, and solvent amount on the properties of the hydrogels were investigated. The composition of the hydrogels was confirmed by Fourier transform infrared spectroscopy. Equilibrium swelling studies in the pH range of 1.2-7 revealed that the extent of swelling increased with increasing pH up to a pH of about 6, when no further carboxylic acid deprotonation occurred. Studies in Caco-2 colorectal carcinoma cells confirmed the cytocompatibility of these materials at concentrations of up to 5 mg/mL. PMID:19536838

  2. Preparation and study of dialkyl nitroxide radicals

    International Nuclear Information System (INIS)

    These radicals are obtained by oxidation of N-hydroxy-imides with lead tetracetate or p-nitro-perbenzoic acid. These imides are prepared by heating dicarboxylic acids anhydrides with benzyloxy-amine followed by catalytic hydrogenation of N-benzyloxy-imides so obtained. Two series of radicals have mainly been studied, the first concerning five-membered cyclic imides, the second six-membered cyclic imides, these molecules having methyls substituents or no on the carbon ring. N. M. R. spectra of some O-benzyl-imides have been analysed. These different results have made it possible to study the conformation and stereochemistry of these imides. (author)

  3. Radical Scavenging Effects of Different Veronica species

    Directory of Open Access Journals (Sweden)

    Ummuhan ?ebnem Harput

    2011-01-01

    Full Text Available It is well known that the excessive production of reactive oxygen species is hazardous for living organisms and damages major cellular constituents such as DNA, lipid and protein. To find new products reducing free radical damage is very important researches in recent pharmaceutical investigations. Considering this information, fourteen Veronica species are decided to research in the view point of their antioxidant capacity and the chemical content. Water extracts of the plants were tested for their radical scavenging activity against 2,2-diphenyl-1-picryl hydrazyl (DPPH, superoxide (SO and nitric oxide (NO radicals spectroscopically. Dose dependent radical scavenging activity was observed and the results were found to be comparable to that of ascorbic acid, quercetin and BHA which are known antioxidative compounds. In addition, gallic acid equivalent total phenolic contents of the plants were also determined using Folin-Ciocalteau reagent. The most significant scavenging activity was found for V. chamaedrys against SO radical (IC50 113.40 ?g/ml and V. officinalis against DPPH and NO radicals (IC50 40.93 ?g/ml, 570.33 ?g/ml, respectively .

  4. Cistectomía radical robótica / Robotic radical cystectomy

    Scientific Electronic Library Online (English)

    Burak, Turna; Monish, Aron; Georges-Pascal, Haber; Inderbir S., Gill; Jihad H., Kaouk.

    2007-05-01

    Full Text Available Objetivos: En la última década hemos visto un tremendo crecimiento en la implantacion y desarrollo de los robots quirúrgicos. Popularizados por la prostatectomía radical, las técnicas robóticas están siendo, en la actualidad, muy aplicadas en la cistectomía radical. Trataremos aquí de revisar el des [...] arrollo y estado actual de la cistectomía radical robótica (CRR) en la práctica contemporánea de la urología. Métodos: Se ha revisado toda la literatura publicada, entre 1995 y 2007, en la base de datos de la Biblioteca Nacional de Medicina (MEDLINE) utilizando las palabras clave: robótica, asistido por robot, laparoscópica y cistectomía. Desde el primer trabajo en 2003, se han encontrado 9 originales publicados. Se valoraron con respecto a la técnica, ventajas y desventajas perioperatorias y resultados oncológicos. Describimos asimismo nuestra experiencia inicial, aún no publicada. Resultados: En este momento todos los artículos publicados sobre la CRR se basan en un número pequeño de pacientes con seguimientos a corto plazo. No obstante, demuestran la viabilidad de la CRR con resultados perioperatorios esperanzadores. Comparada con la cistectomía radical abierta (CRA), la CRR parece estar asociada con menor pérdida de sangre, estancia hospitalaria y necesidades analgésicas. Estas ventajas se encuentran asimismo en la cistectomía radical laparoscópica (CRL) y son una función del abordaje mínimamente invasivo. El tiempo quirúrgico es mayor, de forma considerable cuando el tiempo intestinal se realiza de manera intracorpórea. Conclusiones: La cistectomía radical robótica está en evolución. La viabilidad técnica ha sido demostrada. Los resultados perioperatorios iniciales son prometedores. Los resultados oncológicos esperan identificar el papel de la misma en el manejo del cáncer de vejiga. Se necesitan ensayos prospectivos y aleatorizados comparando la CRA con la CRR y la CRL. Abstract in english Objectives: The last decade has seen tremendous growth of surgical robotics. Popularized for radical prostatectomy, robotic techniques are now increasingly being applied to radical cystectomy. Herein, we review the development and current status of robotic radical cystectomy (RRC) in contemporary ur [...] ological practice. Methods: Between 1995 and 2007 published literature was reviewed using the National Library of Medicine database and the following key words: robotic, robot-assisted, laparoscopic and cystectomy. Since the first report in 2003, nine published original reports were identified. These were evaluated with regards to the technique, advantages and disadvantages, perioperative and oncological outcomes. Our initial experience, as yet unpublished, is also described. Results: At this writing, all published papers on RRC are based on small number of patients with short-term follow-up. Nevertheless, they have demonstrated the technical feasibility of RRC with encouraging perioperative outcomes. Compared to open radical cystectomy (ORC), RRC appears to be associated with decreased blood loss, hospital stay and analgesic requirement. These advantages are also found with laparoscopic radical cystectomy (LRC) and are a function of the minimally invasive approach. The operating time is longer, markedly so when the bowel work is performed intracorporeally. Conclusions: RRC is in evolution. Technical feasibility has been demonstrated. Initial perioperative outcomes are encouraging. Oncological outcomes are awaited to identify the role of RRC in the management of bladder cancer. Multi-center prospective randomized trials comparing ORC with RRC and LRC are necessary.

  5. Oxidation of SO2 by stabilized Criegee intermediate (sCI radicals as a crucial source for atmospheric sulfuric acid concentrations

    Directory of Open Access Journals (Sweden)

    M. Boy

    2013-04-01

    Full Text Available The effect of increased reaction rates of stabilized Criegee intermediates (sCIs with SO2 to produce sulfuric acid is investigated using data from two different locations, SMEAR II, Hyytiälä, Finland, and Hohenpeissenberg, Germany. Results from MALTE, a zero-dimensional model, show that using previous values for the rate coefficients of sCI + SO2, the model underestimates gas phase H2SO4 by up to a factor of two when compared to measurements. Using the rate coefficients recently calculated by Mauldin et al. (2012 increases sulfuric acid by 30–40%. Increasing the rate coefficient for formaldehyde oxide (CH2OO with SO2 according to the values recommended by Welz et al. (2012 increases the H2SO4 yield by 3–6%. Taken together, these increases lead to the conclusion that, depending on their concentrations, the reaction of stabilized Criegee intermediates with SO2 could contribute as much as 33–46% to atmospheric sulfuric acid gas phase concentrations at ground level. Using the SMEAR II data, results from SOSA, a one-dimensional model, show that the contribution from sCI reactions to sulfuric acid production is most important in the canopy, where the concentrations of organic compounds are the highest, but can have significant effects on sulfuric acid concentrations up to 100 m. The recent findings that the reaction of sCI + SO2 is much faster than previously thought together with these results show that the inclusion of this new oxidation mechanism could be crucial in regional as well as global models.

  6. Setting the stage for electron transfer: Molecular basis of ABTS-binding to four laccases from Trametes versicolor at variable pH and protein oxidation state

    DEFF Research Database (Denmark)

    Christensen, Niels Johan; Kepp, Kasper Planeta

    2014-01-01

    Laccases are multi-copper oxidases having exquisite oxidation power, high stability, and multiple industrial applications. Although Km varies ?1000-fold across laccases, the molecular basis of substrate binding is poorly understood. Furthermore, laccase isoenzymes vary substantially in stability and activity for unknown reasons, and are thus useful probes of stability-function trade-offs relevant to protein engineering. We report here the first systematic comparison of ABTS-binding to different proteins, i.e. the four isoforms of Trametes versicolor, using a combination of sequence clustering, density functional theory calculations, homology modeling, and multiple induced-fit docking protocols at variable pH-dependent protonation states and T1-copper oxidation state. Clustering analysis provided a systematic overview of laccases across Trametes and revealed distinct isoenzyme classes (A–J) with the four T. versicolor isoforms belonging to separate classes. The T1 oxidation state had minor effect on ABTS binding, whereas the protonation state of Asp206 was important, consistent with site-directed mutagenesis studies. The absence of active poses for the ?-isoform agrees with its large Km, whereas the ?-isoform with the smallest Km also had most active poses with protonated Asp206 corresponding to its pHopt?2. Protonated Asp can bind to ABTS to form strong, active conformations partially explaining the low pHopt of fungal laccases toward ABTS. We identified several laccase properties optimal for ABTS binding. Notably, very high (R2?0.99) correlation was observed between logKm (ABTS) and binding-pocket charge due to sites 157, 161, 269, 271, and 333, i.e. laccases optimal for ABTS turnover have positively charged anchor points in their pockets. Our work also demonstrates how activity-constraints can markedly improve docking to reduce inactive false positives.

  7. Anticancer compound ABT-263 accelerates apoptosis in virus-infected cells and imbalances cytokine production and lowers survival rates of infected mice.

    Science.gov (United States)

    Kakkola, L; Denisova, O V; Tynell, J; Viiliäinen, J; Ysenbaert, T; Matos, R C; Nagaraj, A; Ohman, T; Kuivanen, S; Paavilainen, H; Feng, L; Yadav, B; Julkunen, I; Vapalahti, O; Hukkanen, V; Stenman, J; Aittokallio, T; Verschuren, E W; Ojala, P M; Nyman, T; Saelens, X; Dzeyk, K; Kainov, D E

    2013-01-01

    ABT-263 and its structural analogues ABT-199 and ABT-737 inhibit B-cell lymphoma 2 (Bcl-2), BCL2L1 long isoform (Bcl-xL) and BCL2L2 (Bcl-w) proteins and promote cancer cell death. Here, we show that at non-cytotoxic concentrations, these small molecules accelerate the deaths of non-cancerous cells infected with influenza A virus (IAV) or other viruses. In particular, we demonstrate that ABT-263 altered Bcl-xL interactions with Bcl-2 antagonist of cell death (Bad), Bcl-2-associated X protein (Bax), uveal autoantigen with coiled-coil domains and ankyrin repeats protein (UACA). ABT-263 thereby activated the caspase-9-mediated mitochondria-initiated apoptosis pathway, which, together with the IAV-initiated caspase-8-mediated apoptosis pathway, triggered the deaths of IAV-infected cells. Our results also indicate that Bcl-xL, Bcl-2 and Bcl-w interact with pattern recognition receptors (PRRs) that sense virus constituents to regulate cellular apoptosis. Importantly, premature killing of IAV-infected cells by ABT-263 attenuated the production of key pro-inflammatory and antiviral cytokines. The imbalance in cytokine production was also observed in ABT-263-treated IAV-infected mice, which resulted in an inability of the immune system to clear the virus and eventually lowered the survival rates of infected animals. Thus, the results suggest that the chemical inhibition of Bcl-xL, Bcl-2 and Bcl-w could potentially be hazardous for cancer patients with viral infections. PMID:23887633

  8. The Thrombospondin-1 Mimetic ABT-510 Increases the Uptake and Effectiveness of Cisplatin and Paclitaxel in a Mouse Model of Epithelial Ovarian Cancer

    Directory of Open Access Journals (Sweden)

    Nicole E. Campbell

    2010-03-01

    Full Text Available Epithelial ovarian cancer (EOC comprises approximately 90% of ovarian cancers and arises from the surface epithelium. Typical treatment of EOC involves cytoreductive surgery combined with chemotherapy. More recent therapies have targeted the tumor vasculature using antiangiogenic compounds such as thrombospondin-1 (TSP-1. TSP-1 mimetic peptides such as ABT-510 have been created and have been in various clinical trials. We have previously shown that ABT-510 reduces abnormal vasculature associated with tumor tissue and increases the presence of mature blood vessels. It has been hypothesized that treatment with antiangiogenic compounds would allow increased delivery of cytotoxic agents and enhance treatment. In this study, we evaluated the potential role of ABT-510 and various chemotherapeutics (cisplatin and paclitaxel on tumor progression, angiogenesis, and the benefits of combinational treatments on tissue uptake and perfusion using an orthotopic syngeneic mouse model of EOC. Animals were treated with ABT-510 (100 mg/kg per day alone or in combination with cisplatin (2 mg/kg per 3 days or paclitaxel (10 mg/kg per 2 days at 60 days after tumor induction. Radiolabeled and fluorescently labeled paclitaxel demonstrated a significant increase in tumor uptake after ABT-510 treatment. Combined treatment with ABT-510 and cisplatin or paclitaxel resulted in a significant increase in tumor cell and tumor endothelial cell apoptosis and a resultant decrease in ovarian tumor size. Combined treatment also regressed secondary lesions and eliminated the presence of abdominal ascites. The results from this study show that through vessel normalization, ABT-510 increases uptake of chemotherapy drugs and can induce regression of advanced ovarian cancer.

  9. ABT-737 reverses the acquired radioresistance of breast cancer cells by targeting Bcl-2 and Bcl-xL

    OpenAIRE

    Li Ji-Yu; Li Yu-Yang; Jin Wei; Yang Qing; Shao Zhi-Ming; Tian Xing-Song

    2012-01-01

    Abstract Background Acquired radioresistance of cancer cells remains a fundamental barrier to attaining the maximal efficacy of radiotherapy for the treatment of breast cancer. Anti-apoptotic proteins, such as Bcl-2 and Bcl-xL, play an important role in the radioresistance of cancer cells. In the present study, we aimed to determine if ABT-737, a BH3-only mimic, could reverse the acquired radioresistance of the breast cancer cell line MDA-MB-231R by targeting Bcl-2 and Bcl-xL. Methods The rad...

  10. Automatic flow system for sequential determination of ABTS scavenging capacity and Folin-Ciocalteu index: A comparative study in food products

    OpenAIRE

    Magalhães, Luís M.; Segundo, Marcela A.; Reis, Salette; Lima, José L.F.C.; Tóth, Ildikó V.; Rangel, António O. S. S.

    2007-01-01

    In the present work, an automatic flow procedure for the sequential spectrophotometric determination of Folin-Ciocalteu reducing capacity (FC assay) and 2,2 -azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS•+) scavenging capacity expressed as the trolox equivalent (TEAC assay) is proposed for a comparative study of antioxidant properties in food products. Exploiting the flexibility of flow management associated to the computer control offered by multisyringe flow injectio...

  11. Radical formation in single crystals of aromatic amines and radical transformation by light

    International Nuclear Information System (INIS)

    Single crystals of the four aromatic bioamine salts phenylethylamine hydrochloride, tyramine hydrochloride, tryptamine hydrochloride, and histamine dihydrochloride were grown in various states of deuteration. Free radicals were produced by exposure to X-rays between 77 and 300 K and investigated by electron spin resonance spectroscopy. Dissociation of atomic hydrogen from Csub(?) of the aliphatic chain occurs in all compounds studied except tryptamine. However deamination as usually present in the analogous amino acids is not found. The Csub(?)-radical is characterized by an anisotropic Hsub(?)-splitting and two isotropic Hsub(?)-splittings. The latter splittings depend strongly on temperature in tyramine. In comparison to the analogous amino acids, radical formation in the aromatic residues is favoured. Among the seven different aromatic radicals found only one is identified in histamine but two in each of the three other bioamines. Two of these are characterized by hydrogen dissociation which occurs in phenylethylamine and tyramine. One hydrogen addition radical is found in each of the three compounds phenylethylamine, tyramine and histamine. In tryptamine two different addition radicals are detected. One of the two products can be converted into the other by visible light. The reverse process is induced by heat, thus permitting the switching of the radical site reversibly between two different structures. (author)

  12. Radicals derived from 1,4-disubstituted anthraquinones

    International Nuclear Information System (INIS)

    The radicals derived from three 1,4-disubstituted anthraquinones containing NH2, NHMe and OH substituent groups have been studied in methanol solution using the technique of pulse radiolysis. Absorption spectra and rates of formation of semiquinone radical species (DH. and D-.), formed respectively under acidic and alkaline conditions, have been recorded. Aggregation of the ground state dye must be assumed to obtain positive extinction coefficients for the radical formed under alkaline conditions. (author)

  13. (S)-3-methyl-5-(1-methyl-2-pyrrolidinyl) isoxazole (ABT 418): a novel cholinergic ligand with cognition-enhancing and anxiolytic activities: I. In vitro characterization.

    Science.gov (United States)

    Arneric, S P; Sullivan, J P; Briggs, C A; Donnelly-Roberts, D; Anderson, D J; Raszkiewicz, J L; Hughes, M L; Cadman, E D; Adams, P; Garvey, D S

    1994-07-01

    A diversity of nicotinic acetylcholine receptor (nAChR) subtypes has been identified in mammalian brain using recombinant DNA technology. Alterations in the activity of these acetylcholinegated ion channels have been implicated in a number of central nervous system disorders including Alzheimer's disease (AD). The potential therapeutic usefulness of (-)-nicotine [(S)-3-(1-methyl-2-pyrrolidinyl) pyridine], the prototypic agonist at nAChRs, is severely limited by side effects that are the result of activation of both cholinergic and noncholinergic pathways in the central and peripheral nervous systems. This study sought to determine the in vitro selectivity of (S)-3-methyl-5-(1methyl-2-pyrrolidinyl)isoxazole (ABT 418), a novel analog of (-)-nicotine in which the pyridine ring was replaced with an isoxazole bioisotere, to activate nAChRs. ABT 418 was a potent inhibitor of [3H]-cytisine binding to nAChR in rat brain (Ki = 3 nM) but was inactive (Ki > 10,000 nM) in 37 other receptor/neurotransmitter-uptake/enzyme/transduction system binding assays, including those for alpha-bungarotoxin, muscarinic and 5-hydroxytryptamine3 receptors. In PC12 cells, patch-clamp studies indicated that ABT 418 was an agonist with an EC50 value of 209 microM, a potency to activate cholinergic channel currents some 4-fold less than that of (-)-nicotine (52 microM). Channel current responses elicited by ABT 418 were prevented by the cholinergic channel blocker, mecamylamine. ABT 418 was also approximately 10-fold less potent (EC50 value = 380 nM) than (-)-nicotine (40 nM) in increasing [3H]-dopamine release from rat striatal slices, an effect that was blocked by the nAChR antagonist, dihydro-beta-erythroidine (10 microM).2+ In contrast, ABT 418 appeared equipotent with (-)-nicotine in enhancing 86Rb+ flux from mouse thalamic synaptosomes. ABT 418 demonstrated an in vitro pharmacological profile of cholinergic channel activation that was robust at some nAChR, but not others. The reasons for this are unclear. However, a nAChR subtype selectivity may account for the in vitro potency differences of ABT 418 on various neurotransmitter systems, and the substantial separation between the cognitive enhancement/anxiolytic benefits, and the reduced central nervous system side-effect liabilities seen in vivo. ABT 418 represents the first neuronal nAChR ligand that differentiates the toxicities/liabilities and other negative aspects normally associated with liabilities and other negative aspects normally associated with (-)-nicotine from the potential pharmacological benefits of selective cholinergic channel activation. PMID:7518514

  14. Prostatectomia radical laparoscópica Radical laparoscopic prostatectomy

    Directory of Open Access Journals (Sweden)

    OCTAVIO A CASTILLO C

    2011-04-01

    Full Text Available La Prostatectomia radical laparoscópica (PRL se ha convertido en una técnica atractiva para el tratamiento quirúrgico del cáncer de próstata localizado. Si bien, los resultados actuales son inicialmente comparables a la prostatectomia radical abierta, es importante mencionar que la tendencia quirúrgica en cáncer de próstata, se ha modificado a pesar de que no hay estudios que confirmen la superioridad del método endoscópico y hoy, el estándar dorado sigue siendo la prostatectomia radical abierta. Dos rutas de acceso quirúrgico pueden ser utilizadas para la realización de PRL, la vía extraperitoneal y la transperitoneal. Un menor sangrado y menor tasa de transfusión, así como, tiempo de hospitalización y recuperación más cortos, son ventajas incuestionables para los procedimientos laparoscópicos. Los resultados oncológicos y funcionales de la prostatectomia laparoscópica son hoy en día comparables, pero en ningún caso mejores que la técnica retropúbica abierta estándar. Recientemente, Hu y colaboradores, en base a una revisión de cerca de 3.000 pacientes tratados en los Estados Unidos, plantean la posibilidad de que los pacientes tratados con prostatectomia laparoscópica (pura o asistida por robot, pudiesen tener mayor riesgo de recurrencia de la enfermedad. Esta es una posición discutible, ya que el análisis, a pesar de ser extenso es limitado para establecer conclusiones finales en el tema. Es importante recordar que la PRL sigue siendo una intervención técnicamente difícil y debiera ser realizada en centros seleccionados con equipos experimentados. La prostatectomía laparoscópica asistida por Robot, facilita el procedimiento y en suma, pareciera mejorar los resultados oncológicos y funcionales. La PRL es hoy en día una alternativa válida a la prostatectomía retropúbica tradicional, con ciertas ventajas adicionales.Radical laparosocpic prostatectomy (RLP is an attractive therapeutic modality for localized prostate cancer. The results obtained with this technique are similar to those obtained with open radical prostatectomy, which continues to be the gold standard for the treatment of prostate cancer. The surgical access for RLP can be extra-peritoneal or trans-peritoneal. The advantages of laparoscopy are lower bleeding rates, less need for transfusion and shorter recuperation time and hospital stay. The oncological results of RLP are similar, but in any case better, that those obtained with open retropubic radical prostatectomy. Recent reports raised the concern that laparoscopic prostatectomy could have higher rates of relapse of cancer. However this opinion is questionable. RLP is a difficult technique and should be performed by experienced teams. Robot assistance facilitates the procedure and could improve functional and oncological results. Therefore RLP is nowadays an alternative to traditional retropubic prostatectomy.

  15. Prostatectomia radical laparoscópica / Radical laparoscopic prostatectomy

    Scientific Electronic Library Online (English)

    OCTAVIO A, CASTILLO C; IVAR, VIDAL-MORA; RAFAEL, SÁNCHEZ-SALAS.

    2011-04-01

    Full Text Available La Prostatectomia radical laparoscópica (PRL) se ha convertido en una técnica atractiva para el tratamiento quirúrgico del cáncer de próstata localizado. Si bien, los resultados actuales son inicialmente comparables a la prostatectomia radical abierta, es importante mencionar que la tendencia quirúr [...] gica en cáncer de próstata, se ha modificado a pesar de que no hay estudios que confirmen la superioridad del método endoscópico y hoy, el estándar dorado sigue siendo la prostatectomia radical abierta. Dos rutas de acceso quirúrgico pueden ser utilizadas para la realización de PRL, la vía extraperitoneal y la transperitoneal. Un menor sangrado y menor tasa de transfusión, así como, tiempo de hospitalización y recuperación más cortos, son ventajas incuestionables para los procedimientos laparoscópicos. Los resultados oncológicos y funcionales de la prostatectomia laparoscópica son hoy en día comparables, pero en ningún caso mejores que la técnica retropúbica abierta estándar. Recientemente, Hu y colaboradores, en base a una revisión de cerca de 3.000 pacientes tratados en los Estados Unidos, plantean la posibilidad de que los pacientes tratados con prostatectomia laparoscópica (pura o asistida por robot), pudiesen tener mayor riesgo de recurrencia de la enfermedad. Esta es una posición discutible, ya que el análisis, a pesar de ser extenso es limitado para establecer conclusiones finales en el tema. Es importante recordar que la PRL sigue siendo una intervención técnicamente difícil y debiera ser realizada en centros seleccionados con equipos experimentados. La prostatectomía laparoscópica asistida por Robot, facilita el procedimiento y en suma, pareciera mejorar los resultados oncológicos y funcionales. La PRL es hoy en día una alternativa válida a la prostatectomía retropúbica tradicional, con ciertas ventajas adicionales. Abstract in english Radical laparosocpic prostatectomy (RLP) is an attractive therapeutic modality for localized prostate cancer. The results obtained with this technique are similar to those obtained with open radical prostatectomy, which continues to be the gold standard for the treatment of prostate cancer. The surg [...] ical access for RLP can be extra-peritoneal or trans-peritoneal. The advantages of laparoscopy are lower bleeding rates, less need for transfusion and shorter recuperation time and hospital stay. The oncological results of RLP are similar, but in any case better, that those obtained with open retropubic radical prostatectomy. Recent reports raised the concern that laparoscopic prostatectomy could have higher rates of relapse of cancer. However this opinion is questionable. RLP is a difficult technique and should be performed by experienced teams. Robot assistance facilitates the procedure and could improve functional and oncological results. Therefore RLP is nowadays an alternative to traditional retropubic prostatectomy.

  16. Carbohydrate radicals: from ethylene glycol to DNA strand breakage.

    Science.gov (United States)

    von Sonntag, Clemens

    2014-06-01

    Radiation-induced DNA strand breakage results from the reactions of radicals formed at the sugar moiety of DNA. In order to elucidate the mechanism of this reaction investigations were first performed on low molecular weight model systems. Results from studies on deoxygenated aqueous solutions of ethylene glycol, 2-deoxy-d-ribose and other carbohydrates and, more relevantly, of d-ribose-5-phosphate have shown that substituents can be eliminated from the ?-position of the radical site either proton and base-assisted (as in the case of the OH substituent), or spontaneously (as in the case of the phosphate substituent). In DNA the C(4') radical undergoes strand breakage via this type of reaction. In the presence of oxygen the carbon-centred radicals are rapidly converted into the corresponding peroxyl radicals. Again, low molecular weights models have been investigated to elucidate the key reactions. A typical reaction of DNA peroxyl radicals is the fragmentation of the C(4')-C(S') bond, a reaction not observed in the absence of oxygen. Although OH radicals may be the important direct precursors of the sugar radicals of DNA, results obtained with poly(U) indicate that base radicals may well be of even greater importance. The base radicals, formed by addition of the water radicals (H and OH) to the bases would in their turn attack the sugar moiety to produce sugar radicals which then give rise to strand breakage and base release. For a better understanding of strand break formation it is therefore necessary to investigate in more detail the reactions of the base radicals. For a start, the radiolysis of uracil in oxygenated solutions has been reinvestigated, and it has been shown that the major peroxyl radical in this system undergoes base-catalysed elimination of [Formula: see text], a reaction that involves the proton at N(l). In the nucleic acids the pyrimidines are bound at N(l) to the sugar moiety and this type of reaction can no longer occur. Therefore, with respect to the nucleic acids, pyrimidines are good models only in acid solutions where the [Formula: see text] elimination reaction is too slow to compete with the bimolecular reactions of the peroxyl radicals. Moreover, the long lifetime of the radical sites on the nucleic acid strand may allow reactions to occur which are kinetically of first order, and which cannot be studied in model systems at ordinary dose rates. It is therefore suggested to extend model system studies to low dose rates and to oligonucleo-tides. Such studies might eventually reveal the key reactions in radical-induced DNA degradation. PMID:24882513

  17. Gallic Acid Ameliorates Cyclophosphamide-Induced Neurotoxicity in Wistar Rats Through Free Radical Scavenging Activity and Improvement in Antioxidant Defense System.

    Science.gov (United States)

    Oyagbemi, Ademola Adetokunbo; Omobowale, Temidayo Olutayo; Saba, Adebowale Bernard; Olowu, Ebunoluwa Racheal; Dada, Racheal Omolola; Akinrinde, Akinleye Stephen

    2016-07-01

    Cyclophosphamide (CPA) is a widely used anticancer chemotherapeutic agent and its toxicity has been associated with its toxic metabolites phosphormide mustard. Therefore, the ameliorative effect of Gallic acid against neurotoxicity was examined in this study. Sixty rats were grouped into 10 rats per group. Group 1 received saline orally. Group 2 received CPA at 100 mg/kg single dose intraperitoneally on day 1. Groups 3 and 4 were treated with Gallic acid (GA) at 60 and 120 mg/kg body weight only for 10 days and also received a single dose of CPA (100 mg/kg) intraperitoneally on day 1, respectively. Rats in groups 5 and 6 received GA at 60 and 120 mg/kg body weight only for 10 days. Groups 3, 4, 5, and 6 received GA orally. The cerebellar and cerebral malondialdehyde (MDA) contents and hydrogen peroxide generation were significantly (p agents with structure/function similar to GA could be of potential benefit to the pharmaceutical industries as an adjuvant in chemotherapy with little or no side effects. PMID:26716793

  18. Radical chemistry of artemisinin

    Energy Technology Data Exchange (ETDEWEB)

    Denisov, Evgenii T; Solodova, S L; Denisova, Taisa G [Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region (Russian Federation)

    2010-12-29

    The review summarizes physicochemical characteristics of the natural sesquiterpene peroxide artemisinin. The kinetic schemes of transformations of artemisinin radicals under anaerobic conditions are presented and analyzed. The sequence of radical reactions of artemisinin in the presence of oxygen is considered in detail. Special emphasis is given to the intramolecular chain oxidation resulting in the transformation of artemisinin into polyatomic hydroperoxide. The kinetic characteristics of elementary reaction steps involving alkyl, alkoxyl, and peroxyl radicals generated from artemisinin are discussed. The results of testing of artemisinin and its derivatives for the antimalarial activity and the scheme of the biochemical synthesis of artemisinin in nature are considered.

  19. Antimicrobial, free radical scavenging activities and catalytic oxidation of benzyl alcohol by nano-silver synthesized from the leaf extract of Aristolochia indica L.: a promenade towards sustainability

    Science.gov (United States)

    Shanmugam, C.; Sivasubramanian, G.; Parthasarathi, Bera; Baskaran, K.; Balachander, R.; Parameswaran, V. R.

    2015-07-01

    Silver nanoparticles (Ag-NPs) were synthesized from aqueous silver nitrate through a simple route using the leaf extract of Aristolochia indica L. (LAIL) which acted as a reducing as well as capping agent. X-ray diffraction confirmed that the synthesized silver particles have a face centred cubic structure. EDS predicted the presence of elemental silver. The SEM images showed the synthesis of spherically mono-dispersed particles, with nano dimensions accounted by the TEM images. Infra-red spectrum adopted to the different organic functionalities present at the surface of the particles. TGA indicated an overall 11 % weight loss up to 1000 °C, suggesting desorption of biomolecules from the surface. X-ray photoelectron spectroscopy (XPS) analysis revealed the presence of metallic silver nanoparticles. The prepared material was utilized as catalyst in the oxidation of benzyl alcohol with molecular oxygen as the oxidant in methanol, under ambient conditions of temperature and pressure. Also Ag-NPs showed good to moderate anti-microbial activity employing the Agar disc diffusion method against various strains using Ciprofloxacin and Fluconazole as standard. Free radical scavenging activity of the nanoparticles were observed by modified 1,1-diphynyl-2-picrylhydrazyl, DPPH and 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid), ABTS in vitro assays. The work presented here demonstrates the adaptability of the synthesized Ag-NPs in participating as a disinfectant agent, free radical scavenger and an effective oxidation catalyst. The basic premise of attaining sustainability through the green synthesis of smart multifaceted materials has been consciously addressed.

  20. Radical simplification made easy

    Science.gov (United States)

    Zippel, R. E. B.

    1977-01-01

    Problems encountered in manipulating algebraic numbers and functions are discussed. Methods for simplifying nested and un-nested radicals are described. Results obtained are either classical or direct corollaries of classical results.

  1. Homegrown religious radicalization

    DEFF Research Database (Denmark)

    Khawaja, Iram

    2015-01-01

    It has been reported that a growing number of youngsters from Western Europe are engaging in conflicts motivated by religious and political conflicts in the Middle East. This paper aims at exploring the reasons behind this seemingly religious radicalization from the point of view of the youngsters and their families. Existing literature and ways of thinking about the social psychological process of radicalization will be reviewed, such as social identity theory and transformative learning theory...

  2. Violent Radicalization in Europe

    DEFF Research Database (Denmark)

    Dalgaard-Nielsen, Anja

    2010-01-01

    When, why, and how do people living in a democracy become radicalized to the point of being willing to use or directly support the use of terrorist violence against Fellow citizens? This question has been at the center of academic and public debate over the past years as terrorist attacks and foiled plots inspired by militant Islamism have grabbed European and American headlines. This article identifies and discusses empirical studies of radicalization and points to the strengths as well as the ...

  3. Violent Radicalization in Europe

    DEFF Research Database (Denmark)

    Dalgaard-Nielsen, Anja

    2010-01-01

    When, why, and how do people living in a democracy become radicalized to the point of being willing to use or directly support the use of terrorist violence against fellow citizens? This question has been at the center of academic and public debate over the past years as terrorist attacks and foiled plots inspired by militant Islamism have grabbed European and American headlines. This article identifies and discusses empirical studies of radicalization and points to the strengths as well as the ...

  4. Laparoscopic radical prostatectomy

    OpenAIRE

    Lipke Michael; Sundaram Chandru

    2005-01-01

    Millions of men are diagnosed annually with prostate cancer worldwide. With the advent of PSA screening, there has been a shift in the detection of early prostate cancer, and there are increased numbers of men with asymptomatic, organ confined disease. Laparoscopic radical prostatectomy is the latest, well accepted treatment that patients can select. We review the surgical technique, and oncologic and functional outcomes of the most current, large series of laparoscopic radical prostatectomy ...

  5. Hydroxyl radicals in indoor environments

    Energy Technology Data Exchange (ETDEWEB)

    Sarwar, G.; Corsi, R.; Kimura, Yosuke; Allen, D. [University of Texas, Austin, TX (United States). Center for Energy and Environmental Resources; Weschler, C.J. [Rutgers Univ., Piscataway, NJ (United States). Environmental and Occupational Health Sciences Inst.

    2002-08-01

    Indoor hydroxyl radical concentrations were estimated using a new indoor air quality model which employs the SAPRC-99 atmospheric chemistry model to simulate indoor homogenous reactions. Model results indicate that typical indoor hydroxyl radical concentrations are lower than typical outdoor summertime urban hydroxyl radical levels of 5-10 x 10{sup 6} molecules cm{sup -3}; however, indoor levels can be similar to or greater than typical nighttime outdoor hydroxyl radical levels of approximately 5 x 10{sup 4} molecules cm{sup -3}. Effects of selected parameters on indoor hydroxyl radical concentrations are presented herein. Indoor hydroxyl radical concentrations are predicted to increase non-linearly with increasing outdoor ozone concentrations, indoor alkene emission rates, and air exchange rates. Indoor hydroxyl radical concentrations decrease with increasing outdoor nitric oxide concentrations. Indoor temperature and indoor light intensity have moderate impacts on indoor hydroxyl radical concentrations. Outdoor hydroxyl radical concentrations, outdoor nitrate (NO{sub 3}) radical concentrations, outdoor hydroperoxy radical concentrations, and hydroxyl radical removal by indoor surfaces are predicted to have no appreciable impact on indoor hydroxyl radical concentrations. Production of hydroxyl radicals in indoor environments appears to be controlled primarily by reactions of alkenes with ozone, and nitric oxide with hydroperoxy radical. Estimated indoor hydroxyl radical levels may potentially affect indoor air quality. Two examples are presented in which reactions of d-limonene and {alpha}-pinene with indoor hydroxyl radicals produce aldehydes, which may be of greater concern than the original compounds.(author)

  6. Quantificação de compostos fenólicos e ácido ascórbico em frutos e polpas congeladas de acerola, caju, goiaba e morango / Quantification of phenolic compounds and ascorbic acid in fruits and frozen pulp of acerola, cashew, strawberry and guava

    Scientific Electronic Library Online (English)

    Juliana Mesquita, Freire; Celeste Maria Patto de, Abreu; Denise Alvarenga, Rocha; Angelita Duarte, Corrêa; Natália Rodrigues, Marques.

    2013-12-01

    Full Text Available O crescente interesse da população pela promoção da saúde vem despertando a atenção dos consumidores por alimentos ricos em antioxidantes, combinado com a praticidade do consumo de sucos de frutos processados. O presente trabalho objetivou quantificar e avaliar a capacidade antioxidante de compostos [...] fenólicos e ácido ascórbico em frutas in natura e polpas congeladas. As frutas in natura e polpas congeladas obtidas na região de Lavras - MG foram submetidas à quantificação de compostos fenólicos e ácido ascórbico e os respectivos extratos acetônico-etanólico e acetônico-metanólico. Foram determinadas suas atividades antioxidantes pelos métodos radicalares DPPH e ABTS. O extrato acetônico-metanólico foi mais efetivo para extrair os compostos antioxidantes das amostras. Apenas as polpas congeladas de acerola apresentaram uma redução do teor de compostos fenólicos em relação ao fruto. Para o teor de ácido ascórbico, houve uma redução nas polpas congeladas de acerola e goiaba. As amostras de acerola apresentaram os maiores teores de compostos fenólicos, ácido ascórbico e atividade antioxidante em relação aos demais frutos analisados. Abstract in english The growing public interest in health- promotion, has called the attention of consumers for foods rich in antioxidants, combined with the practicality of the consumption of processed fruit juices. Therefore, this study aimed to quantify and evaluate the antioxidant capacity of phenolic compounds and [...] ascorbic acid in fruits "in natura" and frozen pulps. The fruits "in natura" and frozen pulps from region of Lavras-MG, underwent quantification of phenolic compounds, ascorbic acid and the corresponding extracts acetonic-ethanolic and acetonic-methanolic. Their antioxidant activities were evaluated by DPPH and ABTS radical methods. The extract acetonic-methanolic was more effective to extract the antioxidant compounds from samples. Only frozen acerola pulps showed lower content of phenolic compounds in relation to fruit. For ascorbic acid, there was a reduction in the frozen pulp of acerola and guava. Acerola samples showed higher content of phenolic compounds, ascorbic acid and antioxidant activity compared to other fruits analyzed.

  7. Poly (N-vinyl-2-pyrrolidone-co-acrylic acid): Comparing of Traditional Heating and Microwave-Assisted Free Radical Polymerization

    International Nuclear Information System (INIS)

    In organic chemistry microwave irradiation has become a common heat source and the use of microwave irradiation is also increasingly studied for polymerization reactions. Polymers have been synthesized at long reaction times by classical thermal methods. In contrast, microwave-assisted polymer synthesis is a well-known and most useful method, which is requiring shorter reaction times. In this study, our aims are to compare THPS and MAPS methods between themselves, and investigate the effect of temperature in MAPS method at different parameters such as reaction times, weight average molecular weight (Mw), polydispersity index (PDI), hydrodynamic radius (Rh), intrinsic and Mark Houwink equation constant (a) of copolymers, viscosity Firstly we synthesized N-vinyl-2-pyrrolidone-acrylic acid copolymers (P(VP-co-AA)) both with traditional heating polymer synthesis (THPS) and microwave-assisted polymer synthesis (MAPS) method comparatively in this study. Secondly, to research temperature effect on MAPS method in addition to microwave irradiation power, polymer synthesis at 40 degree C, 50 degree C and 80 degree C were tried. For analyzing of copolymers Fourier Transform Infrared (FT-IR) spectroscopy and Gel Permeation Chromatography (GPC) system with four detectors were used. (author)

  8. Antioxidant capacity and radical scavenging effect of polyphenol rich Mallotus philippenensis fruit extract on human erythrocytes: an in vitro study.

    Science.gov (United States)

    Gangwar, Mayank; Gautam, Manish Kumar; Sharma, Amit Kumar; Tripathi, Yamini B; Goel, R K; Nath, Gopal

    2014-01-01

    Mallotus philippinensis is an important source of molecules with strong antioxidant activity widely used medicinal plant. Previous studies have highlighted their anticestodal, antibacterial, wound healing activities, and so forth. So, present investigation was designed to evaluate the total antioxidant activity and radical scavenging effect of 50% ethanol fruit glandular hair extract (MPE) and its role on Human Erythrocytes. MPE was tested for phytochemical test followed by its HPLC analysis. Standard antioxidant assays like DPPH, ABTS, hydroxyl, superoxide radical, nitric oxide, and lipid peroxidation assay were determined along with total phenolic and flavonoids content. Results showed that MPE contains the presence of various phytochemicals, with high total phenolic and flavonoid content. HPLC analysis showed the presence of rottlerin, a polyphenolic compound in a very rich quantity. MPE exhibits significant strong scavenging activity on DPPH and ABTS assay. Reducing power showed dose dependent increase in concentration absorption compared to standard, Quercetin. Superoxide, hydroxyl radical, lipid peroxidation, nitric oxide assay showed a comparable scavenging activity compared to its standard. Our finding further provides evidence that Mallotus fruit extract is a potential natural source of antioxidants which have a protective role on human Erythrocytes exhibiting minimum hemolytic activity and this justified its uses in folklore medicines. PMID:25525615

  9. Fenoles totales y capacidad antioxidante estimada con los ensayos DPPH/ABTS en rosas en soluciones preservantes / Total phenols and antioxidant capacity estimated with DPPH/ABTS assays in roses on preservative solutions

    Scientific Electronic Library Online (English)

    Nadia, Zenil Lugo; Ma. Teresa, Colinas León; Cecilio, Bautista Bañuelos; Tito Roque, Vázquez Rojas; Héctor, Lozoya Saldaña; Ma.Teresa, Martínez Damián.

    2014-09-01

    Full Text Available Tallos de rosa 'Freedom' se evaluaron en dos soluciones preservantes: 8-citrato de hidroxiquinoleina (HQC) y Chrysal CLEAR Professional 2® T-bag (CHRYSAL) en un pulso de 24 h a temperatura ambiente (24 ± 2 °C, 75 % HR) y agua como testigo. Se utilizó un diseño completamente al azar con cuatro repeti [...] ciones, la unidad experimental fue un tallo floral. Se evaluó la vida de florero, el contenido de fenoles totales con el método colorimétrico de Folin-Ciocalteauy la capacidad antioxidante total (caT) con los ensayos DPPH y ABTS tanto en hoja como en pétalo. Se realizó el ANOVA y correlaciones simples entre la caT y el contenido de fenoles, y entre ambos ensayos. Los resultados muestran que las soluciones preservantes promueven un aumento en la caT y contenido de fenoles totales en hoja, pero no en pétalo. Las hojas de los tallos florales tratados con CHRYSAL presentaron los mayores contenidos de fenoles totales y caT, mientras que el testigo los menores. La vida media de florero fue de: 13, 11 y 9 días para los tratados con CHRYSAL, HQC y el testigo, respectivamente. El contenido de fenoles totales presentó una estrecha relación positiva (?? 0.01) con la caT: 0.87 y 0.85 medida con el ABTS y 0.92 y 0.85 con el DPPH en hoja y pétalo respectivamente y también ambos métodos se correlacionaron entre sí positiva y significativamente (r= 0.91) en hoja y (r= 0.93) en pétalo. Abstract in english Rose stems 'Freedom' were evaluated in two preservative solutions: 8-hydroxyquinoline citrate (HQC) and Chrysal CLEAR® Professional 2 T-bag (CHRYSAL) in a pulse of 24 h at room temperature (24 ± 2 °C, 75% HR) and water as control. A completely randomized design with four replications was used; the e [...] xperimental unit was a flower stem. Vase life, total phenolic content with the colorimetric method Folin-Ciocalteauy, total antioxidant capacity (caT) with DPPH and ABTS assays in both leaf and petal was evaluated. ANOVA and simple correlations between caT and content of phenols and between both assays was made. The results show that preservative solutions promote an increase in caT and total phenolic content in leaf, but not in petal. The leaves of the flowering stems treated with CHRYSAL had the highest contents of total phenols and caT, while control the lowest. The average vase life was 13, 11 and 9 days for those treated with CHRYSAL, HQC and control, respectively. The total phenolic content showed a strong positive relation (? ?0.01) with caT: 0.87 and 0.85 measured with ABTS and 0.92 and 0.85 with DPPH in leaf and petal respectively and also both methods were correlated positively and significantly with each other (r= 0.91) in leaf and (r= 0.93) in petal.

  10. Radical scavenging activities of Tyr-, Trp-, Cys- and Met-Gly and their protective effects against AAPH-induced oxidative damage in human erythrocytes.

    Science.gov (United States)

    Zheng, Lin; Dong, Hongzhu; Su, Guowan; Zhao, Qiangzhong; Zhao, Mouming

    2016-04-15

    Radical scavenging activities of Tyr-, Trp-, Cys- and Met-Gly and their protective effects against AAPH-induced oxidative damage in erythrocytes were evaluated in this study. This damage includes hemolysis, oxidation of hemoglobin, formation of MDA and the depletion of glutathione (GSH) and catalase (CAT). Results showed that Tyr- and Trp-Gly could quench the radicals effectively in ABTS and ORAC assays with TE (Trolox equivalent) values of more than 1.0?mol TE/?mol, followed by Cys- and Met-Gly. All these dipeptides could protect erythrocytes against AAPH-induced hemolysis in a dose-dependent manner. They could also significantly (perythrocytes. The protective effects of these dipeptides decreased in the following order: Trp-Gly>Tyr-Gly>Met-Gly>Cys-Gly, which were consistent with their peroxyl radical scavenging activities. It suggested that these dipeptides might protect erythrocytes against AAPH-induced oxidative damage, mainly by acting as the direct radical scavengers. PMID:26617020

  11. Free radical scavenging activity of leaves of Alocasia indica (Linn

    Directory of Open Access Journals (Sweden)

    Mulla W

    2009-01-01

    Full Text Available The free radical scavenging potential of the plant Alocasia indica (Linn. was studied by using different antioxidant models of screening like scavenging of 1,1-diphenyl-2-picryl hydrazyl radical, nitric oxide radical, superoxide anion radical, hydroxyl radical, iron chelating activity, total antioxidant capacity, non-enzymatic glycosylation of haemoglobin, rapid screening for antioxidant compounds by thin layer chromatography. The hydroalcoholic extract at 1000 ?g/ml showed maximum scavenging of superoxide radical (87.17 by riboflavin-NBT-system, followed by scavenging of stable radical 1,1-diphenyl-2-picryl hydrazyl radical (83.48%, nitric oxide radical (74.09% hydroxyl radical (60.96% at the same concentration. However the extract showed only moderate activity by iron chelation (68.26%. That could be due to higher phenolic content in the extract. This finding suggests that hydro alcoholic extract of A. indica possess potent in vitro antioxidant activity as compared to the standard ascorbic acid. The results justify the therapeutic applications of the plant in the indigenous system of medicine, augmenting its therapeutic value.

  12. Free-radical reactions of glycerolipids and sphingolipids

    Science.gov (United States)

    Yurkova, I. L.

    2012-02-01

    Free-radical reactions of glycero- and sphingolipids occurring in their polar moiety (fragmentation) and in their hydrophobic residue (peroxidation) under the action of reactive oxygen species are considered. The main attention is focused on free-radical fragmentation; its mechanism and regularities are discussed. Lipid peroxidation has been shown to modify the residues of polyunsaturated fatty acids, while the free-radical fragmentation results in the cleavage of ester, O-glycosidic and amide bonds in lipid molecules to give glycerophosphatides, ceramides and fatty acid amides functioning as secondary messengers in biosystems. The bibliography includes 132 references.

  13. Data on the DNA damaging and mutagenic potential of the BH3-mimetics ABT-263/Navitoclax and TW-37

    Science.gov (United States)

    Green, Maja M.; Shekhar, Tanmay M.; Hawkins, Christine J.

    2016-01-01

    Unfortunately, the mutagenic activities of chemotherapy and radiotherapy can provoke development of therapy-induced malignancies in cancer survivors. Non-mutagenic anti-cancer therapies may be less likely to trigger subsequent malignant neoplasms. Here we present data regarding the DNA damaging and mutagenic potential of two drugs that antagonize proteins within the Bcl-2 family: ABT-263/Navitoclax and TW-37. Our data reveal that concentrations of these agents that stimulated Bax/Bak-dependent signaling provoked little DNA damage and failed to trigger mutations in surviving cells. The data supplied in this article is related to the research work entitled "Inhibition of Bcl-2 or IAP proteins does not provoke mutations in surviving cells" [1].

  14. An exploratory study on the peroxyl-radical-scavenging activity of 2,6-dimethyl-5-hepten-2-ol and its heterocyclic analogues

    Science.gov (United States)

    Stobiecka, Agnieszka; Sikora, Magdalena; Bonikowski, Rados?aw; Kula, Józef

    2016-03-01

    The structural properties and radical scavenging activity of 2,6-dimethyl-5-hepten-2-ol (1) and its new heterocyclic analogues, i.e. 2-methyl-4-(5-methylfuran-2-yl)-butan-2-ol (2) and 2-methyl-4-(5-methylthiophen-2-yl)-butan-2-ol (3) and have been studied by using the experimental and theoretical methods for the first time. Activity of title compounds against the peroxyl radical was determined by using standard fluorimetric test, i.e. the Oxygen Radical Absorbance Capacity assay (ORACFL). Furthermore, the electron-donating ability of odorants has been evaluated by using colorimetric ABTS assay. According to the experimental results obtained from the ORACFL test 2,6-dimethyl-5-hepten-2-ol was characterized by the highest activity in comparison with the novel counterparts. Nevertheless, all investigated compounds exhibited pronounced anti-peroxyl radical activity comparable to that exerted by the one of the most prominent antioxidant among the monoterpene alcohols, i.e. by linalool. On the other hand, the title compounds exerted relatively low capacity to quench the radical cation of ABTS. Theoretical calculations based on the Density Functional Theory (DFT) method with the hybrid functional B3LYP were carried out in order to investigate selected structural and electronic properties including the geometrical parameters as well as the energy of frontier molecular orbitals of parent molecules and the resulting radicals. Furthermore, the possible mechanism of peroxyl-radical-scavenging has been determined by using the thermodynamic descriptors such as the bond dissociation enthalpies (BDEs) and ionization potentials (IPs). These theoretical data pointed out the relevance of HAT mechanism in the peroxyl-radical-scavenging exhibited by 2,6-dimethyl-5-hepten-2-ol and its new heterocyclic analogues in polar and non-polar medium.

  15. Thermochemistry of fluorocarbon radicals

    International Nuclear Information System (INIS)

    The ideal gas thermodynamic functions (entropy, heat capacity, enthalpy) for free radicals can only be determined by statistical thermodynamics as the species are much too reactive for extended calorimetric measurements. These functions have been calculated in the rigid rotor, harmonic oscillator approximation and hindered, internal rotations have been treated by Pitzer's semiclassical approximations. This approximation has been shown to give quite satisfactory agreement with exact calculations. These calculations require detailed structural and mechanical data for the free radical. Very little of these data are known, though difluoromethylene and trifluoromethyl are exceptions, so that much must be estimated. Though these data are limited, they can be combined with group additivity to form the basis for the thermochemistry of several classes of free radicals. Caution must be exercised when this estimation procedure is applied to compounds with groups of very different polarity. 41 references, 12 tables

  16. The Corrole Radical.

    Science.gov (United States)

    Schweyen, Peter; Brandhorst, Kai; Wicht, Richard; Wolfram, Benedikt; Bröring, Martin

    2015-07-01

    The reaction of 5,10,15-trimesitylcorrole (H3 cor) with tungsten hexachloride and tungsten hexacarbonyl resulted in the unexpected formation of the 3,17-dichloro-5,10,15-trimesitylcorrole radical (H2 cor*) as an air-stable product. X-ray crystallography proved the planarization of the corrole radical structure, which was rationalized by the reduced steric hindrance of two versus three hydrogen atoms inside the N4 cavity. Although the aromaticity was lost, no specific changes in C-C or C-N bond distances could be observed. The regioselectivity of the two-fold chlorination is the result of the nucleophilic attack of chloride ions to an oxidized corrole macrocycle, and is supported by DFT results. The corrole radical acts as a dianionic ligand and allows the insertion of the divalent zinc(II) cation, which usually does not form neutral corrole complexes. PMID:26074281

  17. Anesthesia for radical prostatectomy

    Directory of Open Access Journals (Sweden)

    Hadži-?oki? J.

    2005-01-01

    Full Text Available Radical prostatectomy is one of most common treatment options currently recommended for clinically localized prostate cancer. Evaluation of intraoperative and postoperative complications is important in evaluation of relative morbidity of this treatment option. Furthermore, investigation of complications of surgical treatment in correlation with not only surgical technique, but comorbidity, ASA stage and anesthetic technique enables improvements in complete perioperative treatment and decrease of incidence of complications resulting from the procedure. Improvement of anesthetic techniques and use of new anesthetic agents contributes to better outcome of surgical treatment. For radical surgery, combined epidural analgesia and general anesthesia reduces postoperative complications and mortality. Benefits can be conferred most likely by altered coagulation activation in surgery, increased blood flow, reduction of operative stress response. Modalities for reduction of intraoperative blood loss during radical prostatectomy are normovolemic haemodilution, preoperative donation of blood for autologus transfusion and use of erythropoietin for increasing red cell mass.

  18. Laparoscopic radical prostatectomy

    Directory of Open Access Journals (Sweden)

    Lipke Michael

    2005-01-01

    Full Text Available Millions of men are diagnosed annually with prostate cancer worldwide. With the advent of PSA screening, there has been a shift in the detection of early prostate cancer, and there are increased numbers of men with asymptomatic, organ confined disease. Laparoscopic radical prostatectomy is the latest, well accepted treatment that patients can select. We review the surgical technique, and oncologic and functional outcomes of the most current, large series of laparoscopic radical prostatectomy published in English. Positive margin rates range from 2.1-6.9% for pT2a, 9.9-20.6% for pT2b, 24.5-42.3% for pT3a, and 22.6-54.5% for pT3b. Potency rates after bilateral nerve sparing laparoscopic radical prostatectomy range from 47.1 to 67%. Continence rates at 12 months range from 83.6 to 92%.

  19. Antioxidant activity and free radical scavenging capacity of phenolic extracts from Helicteres isora L. and Ceiba pentandra L.

    OpenAIRE

    Loganayaki, Nataraj; Siddhuraju, Perumal; Manian, Sellamuthu

    2011-01-01

    In the present study, antioxidant activities of the phenolic extracts from H. isora fruits and C. pentandra seeds were investigated by employing established in vitro systems, which included reducing power, OH?, DPPH?, ABTS?+, linoleic acid emulsion, metal chelation and antihemolytic activity. The extracts of C. pentandra contained relatively higher levels of total phenolics and flavonoids than those of H. isora. All the extracts showed dose dependent reducing power activity and moreover, they...

  20. Sources, sinks, and mechanisms of hydroxyl radical (•OH) photoproduction and consumption in authentic acidic continental cloud waters from Whiteface Mountain, New York: The role of the Fe(r) (r = II, III) photochemical cycle

    Science.gov (United States)

    Arakaki, Takemitsu; Faust, Bruce C.

    1998-02-01

    Hydroxyl radical (•OH) photoproduction in 25 authentic acidic (pH = 2.9-4.4) continental cloud waters from Whiteface Mountain, New York was quantified by phenol formed from the •OH-mediated oxidation of benzene (1.2 mM) that was added as an •OH scavenger. Based on the effect of added bisulfite (HSO3-/HOSO2-), an HOOH sink, the •OH photoproduction in these samples was apportioned into two categories: HOOH-dependent sources (dominant), and HOOH-independent sources (minor). On average only a small percentage (median = 9.4%, mean±standard deviation = 16±12%) of the HOOH-dependent •OH source is due to direct photolysis (313 nm) of HOOH. Nearly all of the HOOH-dependent •OH source is accounted for by an iron(II)-HOOH photo-Fenton reaction mechanism (Fe(II) + HOOH ? Fe(III) + •OH + OH-) that is initiated by photoreduction of Fe(III) to Fe(II) in the presence of HOOH. A photostationary state is established, involving rapid photolysis of Fe(III) to form Fe(II), and rapid reoxidation of Fe(II) to Fe(III). Consequently, a new term is introduced, Fe(r) (r = II, III), to represent the family of labile Fe(III) and Fe(II) species whose rapid photoredox cycling drives the Fenton production of •OH. The Fe(r) photochemical cycle, which drives the aqueous phase photoformation of •OH, is analogous to the classical NOx photochemical cycle, which drives the gas phase formation of O3 and thus •OH. Based on the cloud waters studied here, the iron(II)-HOOH photo-Fenton reaction is a significant source of •OH to acidic continental cloud waters in comparison to gas-to-drop partitioning processes. Filtering (0.5 ?m Teflon) cloud water samples had little effect on the •OH photoformation kinetics. Measured lifetimes of aqueous •OH ranged from 2.4 to 10.6 ?s in these cloud waters, and decreased with increasing concentration of dissolved organic carbon. In acidic atmospheric water drops, the principal aqueous sinks for •OH will be reactions with dissolved organic compounds, bisulfite, and Cl-. Given such short chemical reaction lifetimes, little of the aqueous phase photoformed •OH is likely to escape to the gas phase.

  1. Biocompatible and biodegradable poly(Tannic Acid) hydrogel with antimicrobial and antioxidant properties.

    Science.gov (United States)

    Sahiner, Nurettin; Sagbas, Selin; Sahiner, Mehtap; Silan, Coskun; Aktas, Nahit; Turk, Mustafa

    2016-01-01

    A novel resourceful bulk poly(Tannic Acid) (p(TA)) hydrogel was prepared by crosslinking TA molecules with an epoxy crosslinker, trimethylolpropane triglycidyl ether (TMPGDE), in an autoclave at 90°C for 2h. The obtained p(TA) hydrogels were in disk form and have highly porous morphology. The swelling characteristics of p(TA) hydrogels were investigated in wound healing pH conditions of pH 5.4, 7.4, and 9 at 37.5°C, and the hydrogels showed good swelling and moisture content behavior. Especially, p(TA) hydrogels were found to be sensitive to pH 9 with 1669% maximum swelling. P(TA) hydrogels were completely degraded at pH 9 hydrolytically in 9 days. Total phenol contents and the effects of scavenging ABTS(+) radicals of degraded p(TA) hydrogels at pH 5.4, 7.4, and 9 were evaluated and calculated in terms of gallic acid equivalent and trolox equivalent antioxidant capacity, respectively, and found to be very effective. Moreover, degraded p(TA) hydrogels display strong antimicrobial behavior against gram positive Staphylococcus aureus, Bacillus subtilis, gram negative Pseudomonas aeruginosa bacteria strains and Candida albicans fungus strain. The WST-1 results indicated that bulk p(TA) hydrogels have no cyctotoxicity to the L929 fibroblast cell line in vitro. PMID:26526171

  2. Sorafenib Sensitizes Glioma Cells to the BH3 Mimetic ABT-737 by Targeting MCL1 in a STAT3-Dependent Manner

    Directory of Open Access Journals (Sweden)

    Irina Kiprianova

    2015-07-01

    Full Text Available The oncogenic transcription factor signal transducer and activator of transcription 3 (STAT3 is overactivated in malignant glioma and plays a key role in promoting cell survival, thereby increasing the acquired apoptosis resistance of these tumors. Here we investigated the STAT3/myeloid cell leukemia 1 (MCL1 signaling pathway as a target to overcome the resistance of glioma cells to the Bcl-2-inhibiting synthetic BH3 mimetic ABT-737. Stable lentiviral knockdown of MCL1 sensitized LN229 and U87 glioma cells to apoptotic cell death induced by single-agent treatment with ABT-737 which was associated with an early activation of DEVDase activity, cytochrome c release, and nuclear apoptosis. Similar sensitizing effects were observed when ABT-737 treatment was combined with the multikinase inhibitor sorafenib which effectively suppressed levels of phosphorylated STAT3 and MCL1 in MCL1-proficient LN229 and U87 glioma cells. In analogous fashion, these synergistic effects were observed when we combined ABT-737 with the STAT3 inhibitor WP-1066. Lentiviral knockdown of the activating transcription factor 5 combined with subsequent quantitative polymerase chain reaction analysis revealed that sorafenib-dependent suppression of MCL1 occurred at the transcriptional level but did not depend on activating transcription factor 5 which previously had been proposed to be essential for MCL1-dependent glioma cell survival. In contrast, the constitutively active STAT3 mutant STAT3-C was able to significantly enhance MCL1 levels under sorafenib treatment to retain cell survival. Collectively, these data demonstrate that sorafenib targets MCL1 in a STAT3-dependent manner, thereby sensitizing glioma cells to treatment with ABT-737. They also suggest that targeting STAT3 in combination with inducers of the intrinsic pathway of apoptosis may be a promising novel strategy for the treatment of malignant glioma.

  3. Sorafenib Sensitizes Glioma Cells to the BH3 Mimetic ABT-737 by Targeting MCL1 in a STAT3-Dependent Manner12

    Science.gov (United States)

    Kiprianova, Irina; Remy, Janina; Milosch, Nelli; Mohrenz, Isabelle V.; Seifert, Volker; Aigner, Achim; Kögel, Donat

    2015-01-01

    The oncogenic transcription factor signal transducer and activator of transcription 3 (STAT3) is overactivated in malignant glioma and plays a key role in promoting cell survival, thereby increasing the acquired apoptosis resistance of these tumors. Here we investigated the STAT3/myeloid cell leukemia 1 (MCL1) signaling pathway as a target to overcome the resistance of glioma cells to the Bcl-2-inhibiting synthetic BH3 mimetic ABT-737. Stable lentiviral knockdown of MCL1 sensitized LN229 and U87 glioma cells to apoptotic cell death induced by single-agent treatment with ABT-737 which was associated with an early activation of DEVDase activity, cytochrome c release, and nuclear apoptosis. Similar sensitizing effects were observed when ABT-737 treatment was combined with the multikinase inhibitor sorafenib which effectively suppressed levels of phosphorylated STAT3 and MCL1 in MCL1-proficient LN229 and U87 glioma cells. In analogous fashion, these synergistic effects were observed when we combined ABT-737 with the STAT3 inhibitor WP-1066. Lentiviral knockdown of the activating transcription factor 5 combined with subsequent quantitative polymerase chain reaction analysis revealed that sorafenib-dependent suppression of MCL1 occurred at the transcriptional level but did not depend on activating transcription factor 5 which previously had been proposed to be essential for MCL1-dependent glioma cell survival. In contrast, the constitutively active STAT3 mutant STAT3-C was able to significantly enhance MCL1 levels under sorafenib treatment to retain cell survival. Collectively, these data demonstrate that sorafenib targets MCL1 in a STAT3-dependent manner, thereby sensitizing glioma cells to treatment with ABT-737. They also suggest that targeting STAT3 in combination with inducers of the intrinsic pathway of apoptosis may be a promising novel strategy for the treatment of malignant glioma. PMID:26297434

  4. Radically enhanced molecular recognition

    KAUST Repository

    Trabolsi, Ali

    2009-12-17

    The tendency for viologen radical cations to dimerize has been harnessed to establish a recognition motif based on their ability to form extremely strong inclusion complexes with cyclobis(paraquat-p-phenylene) in its diradical dicationic redox state. This previously unreported complex involving three bipyridinium cation radicals increases the versatility of host-guest chemistry, extending its practice beyond the traditional reliance on neutral and charged guests and hosts. In particular, transporting the concept of radical dimerization into the field of mechanically interlocked molecules introduces a higher level of control within molecular switches and machines. Herein, we report that bistable and tristable [2]rotaxanes can be switched by altering electrochemical potentials. In a tristable [2]rotaxane composed of a cyclobis(paraquat-p-phenylene) ring and a dumbbell with tetrathiafulvalene, dioxynaphthalene and bipyridinium recognition sites, the position of the ring can be switched. On oxidation, it moves from the tetrathiafulvalene to the dioxynaphthalene, and on reduction, to the bipyridinium radical cation, provided the ring is also reduced simultaneously to the diradical dication. © 2010 Macmillan Publishers Limited. All rights reserved.

  5. Radical School Reform.

    Science.gov (United States)

    Gross, Beatrice, Ed.; Gross, Ronald, Ed.

    This book provides a comprehensive examination of the nature of the school crisis and the ways in which radical thinkers and educators are dealing with it. Excerpts from the writings of Jonathan Kozol, John Holt, Kenneth Clark, and others are concerned with the realities of education in ghettos and suburbs. Paul Goodman, Marshall McLuhan, Sylvia…

  6. MCL-1 and BCL-xL-dependent resistance to the BCL-2 inhibitor ABT-199 can be overcome by preventing PI3K/AKT/mTOR activation in lymphoid malignancies

    Science.gov (United States)

    Choudhary, G S; Al-harbi, S; Mazumder, S; Hill, B T; Smith, M R; Bodo, J; Hsi, E D; Almasan, A

    2015-01-01

    Overexpression of anti-apoptotic BCL-2 family members is a hallmark of many lymphoid malignancies, including chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL) that can be targeted with small molecule inhibitors. ABT-199 is a rationally designed BCL-2 homology (BH)-3 mimetic that specifically binds to BCL-2, but not to MCL-1 and BCL-xL. Although the thrombocytopenia that occurs with navitoclax treatment has not been a problem with ABT-199, clinical trials in CLL could benefit by lowering the ABT-199 concentration through targeting other survival pathways. In this study, we investigated the mechanisms of resistance that develops to ABT-199 therapy by generating ABT-199-resistant (ABT199-R) cell lines via chronic exposure of NHL cell lines to ABT-199. Acquired resistance resulted in substantial AKT activation and upregulation of MCL-1 and BCL-xL levels that sequestered BIM. ABT199-R cells exhibited increased MCL-1 stability and failed to activate BAX in response to ABT-199. The ABT-199 acquired and inherent resistant cells were sensitized to treatment with ABT-199 by inhibitors of the PI3K, AKT, and mTOR pathways, NVP-BEZ235 and GS-1101. NVP-BEZ235, a dual inhibitor of p-AKT and mTOR, reduced MCL-1 levels causing BIM release from MCL-1 and BCL-xL, thus leading to cell death by BAX activation. The PI3K? inhibitor GS-1101 (idelalisib) downregulated MCL-1 and sensitized ABT199-R cells through AKT-mediated BAX activation. A genetic approach, through siRNA-mediated down-regulation of AKT, MCL-1, and BCL-xL, significantly decreased cell survival, demonstrating the importance of these cell survival factors for ABT-199 resistance. Our findings suggest a novel mechanism that modulates the expression and activity of pro-survival proteins to confer treatment resistance that could be exploited by a rational combination therapeutic regimen that could be effective for treating lymphoid malignancies. PMID:25590803

  7. Reaction of hydroxyl radicals with 1-bromo-n-iodoalkanes in aqueous solution: 2c-3e bonded radical cations

    International Nuclear Information System (INIS)

    The transient optical absorption bands (?max=310, 350 nm) formed on reaction of OH radicals with 1-bromo-4-iodobutane (pH=6) are assigned to OH-adduct. In acidic solutions (pH=3.0), the OH adduct is converted to a transient band with ?max=440 nm. This band is assigned to intramolecular radical cation formed on p-orbital overlap of oxidized iodine with bromine. In 1-bromo-3-iodopropane, the hydroxyl radicals react to form absorption band with ?max=400 nm and a small shoulder in 310-330 nm region. In acidic solutions, the absorption of 310-330 nm band decreases and that of 400 nm band increases. The transient band at 400 nm is assigned to intramolecular radical cation. A fraction of OH radical is able to react by electron transfer mechanism at neutral pH. The fraction of OH radical forming OH-adduct at neutral pH decreases and is converted to radical cation in acidic pH. (author). 4 refs

  8. Oxidation of aromatic amines and diamines by OH radicals. Formation and ionization constants of amine cation radicals in water

    International Nuclear Information System (INIS)

    The one-electron oxidation by hydroxyl radicals of aromatic amines and diamines in water was studied using the fast-reaction technique of pulse radiolysis and kinetic absorption spectrophotometry. The following compounds were examined: N,N,N1,N1- tetramethyl-p-phenylenediamine (TMPD), p-phenylenediamine (PD), N,N-dimethyl-p-phenylenediamene (DMPD), N,N,N1,N1-tetramethylbenzidine (TMB), and diphenylamine (DPA). The main initial reaction of the OH radicals is suggested to be an addition to these compounds to give absorption spectra which absorb strongly in the visible and uv regions. These OH radical adducts decay by first-order kinetics and have lifetimes of approximately 5-50 ?sec, dependent on the pH, buffer concentration, and the nature of the aromatic amines and diamines. They decay to give species with somewhat similar absorption spectra and extinction coefficients, which are very long lived in the absence of oxygen. The latter species are assigned to the cation radicals TMPD.+, PD.+, DMPD.+, TMB.+, and DPA.+. The OH radical adducts and the cation radicals have acid-base properties. The pK/sub a/ values of the cation radicals TMPDH.2+, PDH.2+, DMPDH.2+, TMBH.2+, and DPAH.2+ were found to be 5.3, 5.9, 6.1, 5.1, and 4.2, respectively. The results indicate that these aromatic amines and diamines can be oxidized by free radicals to yield the corresponding cation radicals. (U.S.)

  9. Synthesis of novel well-defined poly(vinyl acetate)-b-poly(acrylonitrile) and derivatized water-soluble poly(vinyl alcohol)-b-poly(acrylic acid) block copolymers by cobalt-mediated radical polymerization

    OpenAIRE

    Debuigne, A.; Warnant, J; Jerome, R.; I. K. Voets; Keizer, A (Arie) de; Cohen Stuart, M.A.; Detrembleur, C

    2008-01-01

    Poly(vinyl acetate)¿Co(acac)2 macroinitiators, prepared by cobalt-mediated radical polymerization of vinyl acetate (VAc), were used to synthesize well-defined poly(vinyl acetate)-b-poly(acrylonitrile) (PVAc-b-PAN) block copolymers. Different solvents and temperatures were tested for the polymerization of the acrylonitrile segment by cobalt-mediated radical polymerization (CMRP), and copolymers with low polydispersity were obtained provided that dimethylformamide was used as solvent at 0 °C. T...

  10. Free radical scavenging abilities of polypeptide from Chlamys farreri

    Science.gov (United States)

    Han, Zhiwu; Chu, Xiao; Liu, Chengjuan; Wang, Yuejun; Mi, Sun; Wang, Chunbo

    2006-09-01

    We investigated the radical scavenging effect and antioxidation property of polypeptide extracted from Chlamys farreri (PCF) in vitro using chemiluminescence and electron spin resonance (ESR) methods. We examined the scavenging effects of PCF on superoxide anions (O{2/-}), hydroxyl radicals (OH·), peroxynitrite (ONOO-) and the inhibiting capacity of PCF on peroxidation of linoleic acid. Our experiment suggested that PCF could scavenge oxygen free radicals including superoxide anions (O{2/-}) (IC50=0.3 mg/ml), hydroxyl radicals (OH·) (IC50=0.2 ?g/ml) generated from the reaction systems and effectively inhibit the oxidative activity of ONOO- (IC50=0.2 mg/ml). At 1.25 mg/ml of PCF, the inhibition ratio on lipid peroxidation of linoleic acid was 43%. The scavenging effect of PCF on O{2/-}, OH· and ONOO- free radicals were stronger than those of vitamin C but less on lipid peroxidation of linoleic acid. Thus PCF could scavenge free radicals and inhibit the peroxidation of linoleic acid in vitro. It is an antioxidant from marine products and potential for industrial production in future.

  11. Gangs, Terrorism, and Radicalization

    OpenAIRE

    Scott Decker; David Pyrooz

    2011-01-01

    What can street gangs tell us about radicalization and extremist groups? At first glance, these two groups seem to push the boundaries of comparison. In this article, we examine the important similarities and differences across criminal, deviant, and extremist groups. Drawing from research on street gangs, this article explores issues such as levels of explanation,organizational structure, group process, and the increasingly important role of technology and the Internet in the context of radi...

  12. Salvage robotic radical prostatectomy

    OpenAIRE

    Kaffenberger, Samuel D.; Smith, Joseph A.

    2014-01-01

    Failure of non-surgical primary treatment for localized prostate cancer is a common occurrence, with rates of disease recurrence ranging from 20% to 60%. In a large proportion of patients, disease recurrence is clinically localized and therefore potentially curable. Unfortunately, due to the complex and potentially morbid nature of salvage treatment, radical salvage surgery is uncommonly performed. In an attempt to decrease the morbidity of salvage therapy without sacrificing oncologic effica...

  13. Probability and radical behaviorism

    OpenAIRE

    Espinosa, James M.

    1992-01-01

    The concept of probability appears to be very important in the radical behaviorism of Skinner. Yet, it seems that this probability has not been accurately defined and is still ambiguous. I give a strict, relative frequency interpretation of probability and its applicability to the data from the science of behavior as supplied by cumulative records. Two examples of stochastic processes are given that may model the data from cumulative records that result under conditions of continuous reinforc...

  14. DEMOCRACIA RADICAL Y CIUDADANÍA

    OpenAIRE

    Pedro Pablo Serna

    2008-01-01

    En el presente texto se presentan dos miradas con respecto a la democracia y su relación con el pensamiento liberal, mostrando de manera específica las características principales de la democracia radical y la manera como ésta puede realizar un adecuado encuentro entre lo individual y lo social, sin afectar las garantías mínimas que se le deben dar a todos los individuos para la realización de su propia concepción de bien. Debe propiciar también unas condiciones adecuadas de participación y c...

  15. Impacts of an unknown daytime nitrous acid source on its daytime concentration and budget, as well as those of hydroxyl, hydroperoxyl, and organic peroxy radicals, in the coastal regions of China

    Directory of Open Access Journals (Sweden)

    Y. Tang

    2015-01-01

    Full Text Available Many field experiments have found high nitrous acid (HONO mixing ratios in both urban and rural areas during daytime, but these high daytime HONO mixing ratios cannot be explained well by gas-phase production, suggesting that an unknown daytime HONO source (Punknown could exist. The formula Punknown ≈ 19.60 × NO2 × J(NO2 was obtained using observed data from 13 field experiments across the globe. The additional HONO sources (i.e. the Punknown, HONO emissions, and nighttime hydrolysis conversion of nitrogen dioxide (NO2 on aerosols were coupled into the WRF-Chem model (Weather Research and Forecasting model coupled with Chemistry to assess the Punknown impacts on the concentrations and budgets of HONO and peroxy (hydroxyl, hydroperoxyl, and organic peroxy radicals (ROx (= OH + HO2 + RO2 in the coastal regions of China. Results indicated that the additional HONO sources produced a significant improvement in HONO and OH simulations, particularly in the daytime. Elevated daytime-mean Punknown values were found in the coastal regions of China, with a maximum of 2.5 ppb h?1 in the Beijing–Tianjin–Hebei region. The Punknown produced a 60–250% increase of OH, HO2 and RO2 near the ground in the major cities of the coastal regions of China, and a 5–48% increase of OH, HO2 and RO2 in the daytime meridional-mean mixing ratios within 1000 m above the ground. When the additional HONO sources were included, the photolysis of HONO was dominated in the OH production rate in Beijing, Shanghai and Guangzhou before 10:00 LST with a maximum of 10.01 [7.26 due to the Punknown] ppb h?1 in Beijing, whereas the reaction of HO2 + NO (nitric oxide was dominated after 10:00 LST with a maximum of 9.38 [7.23] ppb h?1 in Beijing. The whole ROx cycle was accelerated by the additional HONO sources, especially the Punknown. The OH production rate was enhanced by 0.67 [0.64] to 4.32 [3.86] ppb h?1 via the reaction of HO2 + NO, and by 0.85 [0.69] to 4.11 [3.61] ppb h?1 via the photolysis of HONO, and the OH loss rate was enhanced by 0.58 [0.55] to 2.03 [1.92] ppb h?1 via the reaction of OH + NO2 and by 0.31 [0.28] to 1.78 [1.64] ppb h?1 via the reaction of OH + CO (carbon monoxide in Beijing, Shanghai and Guangzhou. Similarly, the additional HONO sources produced an increase of 0.31 [0.28] to 1.78 [1.64] ppb h?1 via the reaction of OH + CO and 0.10 [0.09] to 0.63 [0.59] ppb h?1 via the reaction of CH3O2 (methylperoxy radical + NO in the HO2 production rate, and 0.67 [0.61] to 4.32 [4.27] ppb h?1 via the reaction of HO2 + NO in the HO2 loss rate in Beijing, Shanghai and Guangzhou. The above results suggest that the Punknown considerably enhanced the ROx concentrations and accelerated ROx cycles in the coastal regions of China, and could produce significant increases in concentrations of inorganic aerosols and secondary organic aerosols and further aggravate haze events in these regions.

  16. Impacts of an unknown daytime nitrous acid source on its daytime concentration and budget, as well as those of hydroxyl, hydroperoxyl, and organic peroxy radicals, in the coastal regions of China

    Science.gov (United States)

    Tang, Y.; An, J.; Wang, F.; Li, Y.; Qu, Y.; Chen, Y.; Lin, J.

    2015-01-01

    Many field experiments have found high nitrous acid (HONO) mixing ratios in both urban and rural areas during daytime, but these high daytime HONO mixing ratios cannot be explained well by gas-phase production, suggesting that an unknown daytime HONO source (Punknown) could exist. The formula Punknown ? 19.60 × NO2 × J(NO2) was obtained using observed data from 13 field experiments across the globe. The additional HONO sources (i.e. the Punknown, HONO emissions, and nighttime hydrolysis conversion of nitrogen dioxide (NO2) on aerosols) were coupled into the WRF-Chem model (Weather Research and Forecasting model coupled with Chemistry) to assess the Punknown impacts on the concentrations and budgets of HONO and peroxy (hydroxyl, hydroperoxyl, and organic peroxy) radicals (ROx) (= OH + HO2 + RO2) in the coastal regions of China. Results indicated that the additional HONO sources produced a significant improvement in HONO and OH simulations, particularly in the daytime. Elevated daytime-mean Punknown values were found in the coastal regions of China, with a maximum of 2.5 ppb h-1 in the Beijing-Tianjin-Hebei region. The Punknown produced a 60-250% increase of OH, HO2 and RO2 near the ground in the major cities of the coastal regions of China, and a 5-48% increase of OH, HO2 and RO2 in the daytime meridional-mean mixing ratios within 1000 m above the ground. When the additional HONO sources were included, the photolysis of HONO was dominated in the OH production rate in Beijing, Shanghai and Guangzhou before 10:00 LST with a maximum of 10.01 [7.26 due to the Punknown] ppb h-1 in Beijing, whereas the reaction of HO2 + NO (nitric oxide) was dominated after 10:00 LST with a maximum of 9.38 [7.23] ppb h-1 in Beijing. The whole ROx cycle was accelerated by the additional HONO sources, especially the Punknown. The OH production rate was enhanced by 0.67 [0.64] to 4.32 [3.86] ppb h-1 via the reaction of HO2 + NO, and by 0.85 [0.69] to 4.11 [3.61] ppb h-1 via the photolysis of HONO, and the OH loss rate was enhanced by 0.58 [0.55] to 2.03 [1.92] ppb h-1 via the reaction of OH + NO2 and by 0.31 [0.28] to 1.78 [1.64] ppb h-1 via the reaction of OH + CO (carbon monoxide) in Beijing, Shanghai and Guangzhou. Similarly, the additional HONO sources produced an increase of 0.31 [0.28] to 1.78 [1.64] ppb h-1 via the reaction of OH + CO and 0.10 [0.09] to 0.63 [0.59] ppb h-1 via the reaction of CH3O2 (methylperoxy radical) + NO in the HO2 production rate, and 0.67 [0.61] to 4.32 [4.27] ppb h-1 via the reaction of HO2 + NO in the HO2 loss rate in Beijing, Shanghai and Guangzhou. The above results suggest that the Punknown considerably enhanced the ROx concentrations and accelerated ROx cycles in the coastal regions of China, and could produce significant increases in concentrations of inorganic aerosols and secondary organic aerosols and further aggravate haze events in these regions.

  17. The amorphous solid dispersion of the poorly soluble ABT-102 forms nano/microparticulate structures in aqueous medium: impact on solubility

    Directory of Open Access Journals (Sweden)

    Frank KJ

    2012-11-01

    Full Text Available Kerstin J Frank,1,3 Ulrich Westedt,2 Karin M Rosenblatt,2 Peter Hölig,2 Jörg Rosenberg,2 Markus Mägerlein,2 Gert Fricker,3 Martin Brandl11Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark; 2Abbott GmbH and Co. KG, Ludwigshafen, Germany; 3Department of Pharmaceutical Technology, University of Heidelberg, Heidelberg, GermanyAbstract: Amorphous solid dispersions (ASDs are a promising formulation approach for poorly soluble active pharmaceutical ingredients (APIs, because they ideally enhance both dissolution rate and solubility. However, the mechanism behind this is not understood in detail. In the present study, we investigated the supramolecular and the nano/microparticulate structures that emerge spontaneously upon dispersion of an ASD in aqueous medium and elucidated their influence on solubility. The ASD, prepared by hot melt extrusion, contained the poorly soluble ABT-102 (solubility in buffer, 0.05 µg/mL, a hydrophilic polymer, and three surfactants. The apparent solubility of ABT-102 from the ASD-formulation was enhanced up to 200 times in comparison to crystalline ABT-102. At the same time, the molecular solubility, as assessed by inverse equilibrium dialysis, was enhanced two times. Asymmetrical flow field-flow fractionation in combination with a multiangle light-scattering detector, an ultraviolet detector, and a refractometer enabled us to separate and identify the various supramolecular assemblies that were present in the aqueous dispersions of the API-free ASD (placebo and of binary/ternary blends of the ingredients. Thus, the supramolecular assemblies with a molar mass between 20,000 and 90,000 could be assigned to the polyvinylpyrrolidone/vinyl acetate 64, while two other kinds of assemblies were assigned to different surfactant assemblies (micelles. The amount of ABT-102 remaining associated with each of the assemblies upon fractionation was quantified offline with high-performance liquid chromatography–ultraviolet-visible. The polymeric and the micellar fraction contributed to the substantial increase in apparent solubility of ABT-102. Furthermore, a microparticulate fraction was isolated by centrifugation and analyzed by scanning electron microscopy, X-ray scattering, and infrared spectroscopy. The microparticles were found to be amorphous and to contain two of the surfactants besides ABT-102 as the main component. The amorphous microparticles are assumed to be the origin of the observed increase in molecular solubility ("true" supersaturation.Keywords: solid dispersion, AFlFFF, micelles, solubility, supersaturation

  18. Empirical antibiotic therapy (ABT) of lower respiratory tract infections (LRTI) in the elderly: application of artificial neural network (ANN). Preliminary results.

    Science.gov (United States)

    Gueli, Nicolò; Martinez, Andrea; Verrusio, Walter; Linguanti, Adele; Passador, Paola; Martinelli, Valentina; Longo, Giovanni; Marigliano, Benedetta; Cacciafesta, Flaminia; Cacciafesta, Mauro

    2012-01-01

    LRTI are among the most common diseases in developed countries, including chronic obstructive pulmonary disease (COPD), one of the most frequent conditions. Their treatment in general practice is often unsuccessful and this increases hospital admissions. We know, bacterial infections in the elderly show a higher morbidity and mortality, either for more severe symptoms, than in younger adults, or because the causing agent often remains unknown. The need for a quick initiation of ABT often requires to chose on empirical grounds. To date there are no official guidelines for empirical ABT of COPD exacerbations, but only heterogeneous and often conflicting recommendations exist. The aim of our study was to identify a tool to guide the choice of the most effective empirical ABT when symptoms are acute and bacteriological tests cannot be performed. We used an ANN to study 117 patients aged between 55 and 97 years (mean 81.5 ± 8.7 years) (± S.D.), admitted with a diagnosis of pneumonia, COPD exacerbation or pneumonia with respiratory failure. We registered symptoms at onset and some individual variables such as age, sex, risk factors, comorbidity, current drug therapies. Then the ANN was applied to choose ABT in 20 patients versus 20 subjects whose therapy was chosen by the physicians, comparing these groups for therapy's efficacy, mean durations of therapy and hospitalization (H). In the learning phase, the ANN could predict the resolution index 99.05% of the time (i.e., 104 times) with a ± S.D. = 0.23. After the training, during the test phase, the network predicted the resolution index 91.67% of the time (i.e., 11 times) with a ± S.D. = 0.54, thus proving the validity of the relations identified during the learning phase. Preliminary results of the application of our tool, show the ANN allowed us to greatly reduce the duration of the ABT and subsequently of the H. Based on preliminary results, we assume that the use of ANN can make a valuable contribution in the choice of empirical ABT in the course of acute lung diseases in elderly. PMID:21978414

  19. Effects of radical scavengers on aqueous solutions exposed to heavy-ion irradiation using the liquid microjet technique

    Science.gov (United States)

    Nomura, Shinji; Tsuchida, Hidetsugu; Furuya, Ryousuke; Miyahara, Kento; Majima, Takuya; Itoh, Akio

    2015-12-01

    The effects of the radical scavenger ascorbic acid on water radiolysis are studied by fast heavy-ion irradiation of aqueous solutions of ascorbic acid, using the liquid microjet technique under vacuum. To understand the reaction mechanisms of hydroxyl radicals in aqueous solutions, we directly measure secondary ions emitted from solutions with different ascorbic acid concentrations. The yield of hydronium secondary ions is strongly influenced by the reaction between ascorbic acid and hydroxyl radicals. From analysis using a simple model considering chemical equilibria, we determine that the upper concentration limit of ascorbic acid with a radical scavenger effect is approximately 70 ?M.

  20. Silicon based radicals, radical ions, diradicals and diradicaloids.

    Science.gov (United States)

    Chandra Mondal, Kartik; Roy, Sudipta; Roesky, Herbert W

    2016-02-21

    Radicals are an important class of species which act as intermediates in numerous chemical and biological processes. Most of the radicals have short lifetimes. However, radicals with longer lifetimes can be isolated and stored in a pure form. They are called stable radicals. Over the last five decades, the syntheses of several stable radicals have been reported. Recently, highly unstable radicals have been successfully stabilized via strong ?-donation of singlet carbenes. Cyclic aklyl(amino) carbene (cAAC) is regarded as a stronger ?-donor and a better ?-acceptor when compared with that of an N-heterocyclic carbene (NHC). In this article we review preferentially the results of our group to generate stable radical centers on the carbene carbon atoms by employing the so far hidden and unique ability of the cAACs. We focus on the development of new synthetic routes to stable and isolable radicals containing silicon atoms. All the compounds have been well characterized by single crystal X-ray analysis; the mono-radicals have been distinguished by EPR spectroscpy and the ground state of the diradicals has been studied by magnetic susceptibility measurements and theoretical calculations. Many of these compounds are studied by cyclic voltammetry and are often converted to their corresponding radical cations or radical anions via electron abstraction or addition processes. Some of them are stable, having long lifetimes and hence are isolated and characterized thoroughly. Not much information has been obtained on the short lived persistent radical species. Herein, we discuss some of the examples of such a type of species and focus on what kind of chemical reactions are initiated by these short-lived radical species in solution. We also briefly mention the syntheses and charaterization of the so far reported stable silicon centered radicals. PMID:26585359

  1. New free radical scavenging neolignans from fruits of Piper attenuatum

    Science.gov (United States)

    Reddy, S. Divya; Siva, Bandi; Poornima, B.; Kumar, D. Anand; Tiwari, Ashok K.; Ramesh, U.; Babu, K. Suresh

    2015-01-01

    Objective: The aim was to study and identify free radicals scavenging and antihyperglycemic principles in fruit of Piper attenuatum. Materials and Methods: Bioassay guided identification of extracts possessing potent free radical scavenging activity, and isolation of compounds was done. Chloroform extract of P. attenuatum possessing potent radical scavenging activity was also evaluated for antihyperglycemic activity following oral glucose tolerance test in rats. Results: Nine neolignans namely, denudatin B (1), iso-4’, 5’-dimethoxy-3, 4-methylenedioxy-2’-oxo-?3’,5’,8’-8.1’-lignan (2), lancifolin D (3), denudatin A (4), wallichinin (5), piperenone (6), lancifolin C (7), 2-oxo-piperol B (8), piperkadsin A (9) and a crotepoxide (10) was identified in Chloroform extract of P. attenuatum. Neolignans (1-9) displayed potent 2, 2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) radical and piperkadsin A (9) also displayed 1, 1-diphenyl-2-picrylhydrazyl radical scavenging activity. Analysis of structure-activity relationship revealed that presence of furan ring and methoxy groups is an important criterion to influence 2, 2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging potentials. Chloroform extract of P. attenuatum fruit could not display antihyperglycemic activity following oral glucose tolerance test in rats. Conclusion: Neolignans present in P. attenuatum fruits are potent free radical scavengers and this is the first report identifying these compounds and activities in this fruit. PMID:25829760

  2. Structure and lyoluminescent reactions of free radicals of irradiated lactose

    International Nuclear Information System (INIS)

    To determine mechanisms of processes, resulting in lyoluminescence the structure of fren radicals in ?-irradiated lactose was investigated by the method of electron paramagnetic resonance. Analysis of dependences of different radical content in irradiated crystals and lyoluminescent characteristics of these samples on the period of their storing enabled to confirm suggested earlier luminescence mechanism with lambdasub(max)=630 nm of irradiated carbon-hydrate in neutral and acid media. The possibility of controlling the content of different types of radicals in samples by lyoluminescent method was shown

  3. Changes in free-radical scavenging ability of kombucha tea during fermentation.

    Science.gov (United States)

    Jayabalan, R; Subathradevi, P; Marimuthu, S; Sathishkumar, M; Swaminathan, K

    2008-07-01

    Kombucha tea is a fermented tea beverage produced by fermenting sugared black tea with tea fungus (kombucha). Free-radical scavenging abilities of kombucha tea prepared from green tea (GTK), black tea (BTK) and tea waste material (TWK) along with pH, phenolic compounds and reducing power were investigated during fermentation period. Phenolic compounds, scavenging activity on DPPH radical, superoxide radical (xanthine-xanthine oxidase system) and inhibitory activity against hydroxyl radical mediated linoleic acid oxidation (ammonium thiocyanate assay) were increased during fermentation period, whereas pH, reducing power, hydroxyl radical scavenging ability (ascorbic acid-iron EDTA) and anti-lipid peroxidation ability (thiobarbituric assay) were decreased. From the present study, it is obvious that there might be some chances of structural modification of components in tea due to enzymes liberated by bacteria and yeast during kombucha fermentation which results in better scavenging performance on nitrogen and superoxide radicals, and poor scavenging performance on hydroxyl radicals. PMID:26054285

  4. Hydroxyl Radical and Its Scavengers in Health and Disease

    OpenAIRE

    Boguslaw Lipinski

    2011-01-01

    It is generally believed that diseases caused by oxidative stress should be treated with antioxidants. However, clinical trials with such antioxidants as ascorbic acid and vitamin E, failed to produce the expected beneficial results. On the other hand, important biomolecules can be modified by the introduction of oxygen atoms by means of non-oxidative hydroxyl radicals. In addition, hydroxyl radicals can reduce disulfide bonds in proteins, specifically fibrinogen, resulting in their unfoldin...

  5. Lipid peroxyl radicals mediate tyrosine dimerization and nitration in membranes

    OpenAIRE

    Bartesaghi, Silvina; Wenzel, Jorge; Trujillo, Madia; López, Marcos; Joseph, Joy; Kalyanaraman, Balaraman; Radi, Rafael

    2010-01-01

    Protein tyrosine dimerization and nitration by biologically-relevant oxidants usually depend on the intermediate formation of tyrosyl radical (•Tyr). In the case of tyrosine oxidation in proteins associated to hydrophobic biocompartments, the participation of unsaturated fatty acids in the process must be considered since they typically constitute preferential targets for the initial oxidative attack. Thus, we postulate that lipid-derived radicals mediate the one-electron oxidation of tyrosin...

  6. Resonant cavity spectroscopy of radical species

    Science.gov (United States)

    Ritchie, Grant

    2015-04-01

    Photo-oxidation in the troposphere is highly complex, being initiated by short lived radical species, in the daytime dominated by the hydroxyl radical, OH, with contributions from Cl atoms, and at night by either NO3 radicals or ozone. Chemical oxidation cycles, which couple OH, HO2 and peroxy (RO2) radical species, remove primary emitted trace species which are harmful to humans or to the wider environment. However, many of the secondary products produced by atmospheric photo-oxidation are also directly harmful, for example O3, NO2, acidic and multifunctional species, many of which are of low volatility and are able to partition effectively to the condensed phase, creating secondary organic aerosol (SOA), which contributes a significant fraction of tropospheric aerosol, with associated impacts on climate and human health. The accuracy of atmospheric models to predict these impacts necessarily requires accurate knowledge of the chemical oxidative cycling. Two of the simplest intermediates are the hydroperoxy radical, HO2, and the smallest and dominant organic peroxy radical, CH3O2, formed directly by the reactions of OH with CO/O2 and CH4/O2, respectively, and indirectly following the oxidation of larger VOCs. OH, HO2 and RO2 (collectively known as ROx) are rapidly cycled, being at the centre of tropospheric oxidation, and hence are some of the best targets for models to compare with field data. The reaction of HO2 and RO2 with NO constitutes the only tropospheric in-situ source of O3. Despite their importance, neither HO2 nor CH3O2 is measured directly in the atmosphere. HO2 is only measured indirectly following its conversion to OH and CH3O2 is not measured at all. Typically only the sum of RO2 radicals is measured, making no distinction between different organic peroxy radicals. This contribution will detail recent studies using (i) optical feedback cavity enhanced absorption spectroscopy with both quantum and inter-band cascade lasers in the mid-IR, and (ii) near-IR diode laser based noise immune cavity enhanced heterodyne molecular spectroscopy as potential methods for the direct detection of HO2 and CH3O2 at atmospheric levels.

  7. Phenolic antioxidant scavenging of myosin radicals generated by hypervalent myoglobin.

    Science.gov (United States)

    Jongberg, Sisse; Lund, Marianne N; Østdal, Henrik; Skibsted, Leif H

    2012-12-01

    The scavenging activity of extracts of green tea (GTE), white grape (WGE), and rosemary (RE), all plant material with high phenolic content, and of the phenolic compounds 4-methylcatechol (4-MC), (+)-catechin, and carnosic acid toward long-lived myosin radicals generated by reaction with H2O2-activated myoglobin at room temperature (pH 7.5, I=1.0) was investigated by freeze-quench ESR spectroscopy. Myosin radicals were generated by incubating 16 ?M myosin, 800 ?M metmyoglobin, and 800 ?M H2O2 for 10 min, and the phenolic extracts were subsequently added (1% (w/w) phenolic compounds relative to myosin). GTE was able to scavenge myosin radicals and reduce the radical intensity by 65%. Furthermore, a low concentration of 4-MC (33 ?M) was found to increase the radical concentration when added to the myosin radicals, whereas a higher concentration of 4-MC and catechin (330 ?M) was found to scavenge myosin radicals and reduce the overall radical concentration by ?65%. PMID:23163579

  8. Atropisomerism of the Asn ? Radicals Revealed by Ramachandran Surface Topology

    DEFF Research Database (Denmark)

    Gerlei, Klára Z.; Jákli, Imre

    2013-01-01

    C radicals are typically trigonal planar and thus achiral, regardless of whether they originate from a chiral or an achiral C-atom (e.g., C-H + (•)OH ? C• + H2O). Oxidative stress could initiate radical formation in proteins when, for example, the H-atom is abstracted from the C?-carbon of an amino acid residue. Electronic structure calculations show that such a radical remains achiral when formed from the achiral Gly, or the chiral but small Ala residues. However, when longer side-chain containing proteogenic amino acid residues are studied (e.g., Asn), they provide radicals of axis chirality, which in turn leads to atropisomerism observed for the first time for peptides. The two enantiomeric extended backbone structures, •?L and •?D, interconvert via a pair of enantiotopic reaction paths, monitored on a 4D Ramachandran surface, with two distinct transition states of very different Gibbs-free energies: 37.4 and 67.7 kJ/mol, respectively. This discovery requires the reassessment of our understanding on radical formation and their conformational and stereochemical behavior. Furthermore, the atropisomerism of proteogenic amino acid residues should affect our understanding on radicals in biological systems and, thus, reframes the role of the D-residues as markers of molecular aging.

  9. Pomegranate seed oil: Effect on 3-nitropropionic acid-induced neurotoxicity in PC12 cells and elucidation of unsaturated fatty acids composition.

    Science.gov (United States)

    Al-Sabahi, Bushra N; Fatope, Majek O; Essa, Musthafa Mohamed; Subash, Selvaraju; Al-Busafi, Saleh N; Al-Kusaibi, Fatma S N; Manivasagam, Thamilarasan

    2014-09-19

    Background Seed oils are used as cosmetics or topical treatment for wounds, allergy, dandruff, and other purposes. Natural antioxidants from plants were recently reported to delay the onset or progress of various neurodegenerative conditions. Over one thousand cultivars of Punica granatum (Punicaceae) are known and some are traditionally used to treat various ailments. Aim The effect of pomegranate oil on 3-nitropropionic acid- (3-NP) induced cytotoxicity in rat pheochromocytoma (PC12) neuronal cells was analyzed in this study. Furthermore, the analysis of unsaturated fatty acid composition of the seed oil of pomegranate by gas chromatography-electron impact mass spectrometry (GC-MS) was done. Results GC-MS study showed the presence of 6,9-octadecadiynoic acid (C18:2(6,9)) as a major component (60%) as 4,4-dimethyloxazoline derivative. The total extractable oil with light petroleum ether by Soxhlet from the dry seed of P. granatum was 4-6%. The oil analyzed for 48.90 ±?1.50 mg gallic acid equivalents/g of oil, and demonstrated radical-scavenging-linked antioxidant activities in various in vitro assays like the DPPH (2,2-diphenyl-l-picrylhydrazyl, % IP = 35.2 ± 0.9%), ABTS (2,2'-azino-bis-3-ethylene benzothiozoline-6-sulfonic acid, % IP 2.2 ± 0.1%), and ?-carotene bleaching assay (% IP = 26 ± 3%), respectively, which could be due the possible role of one methylene interrupted diynoic acid system for its radical-scavenging/antioxidant properties of oil. The oil also reduced lipid peroxidation, suppressed reactive oxygen species, extracellular nitric oxide, lactate/pyruvate ratio, and lactase dehydrogenase generated by 3-NP- (100 mM) induced neurotoxicity in PC12 cells, and enhanced the levels of enzymatic and non-enzymatic antioxidants at 40 ?g of gallic acid equivalents. Conclusion The protective effect of pomegranate seed oil might be due to the ability of an oil to neutralize ROS or enhance the expression of antioxidant gene. PMID:25238165

  10. Kinetics and mechanism of protection of thymine from sulphate radical anion under anoxic conditions

    Indian Academy of Sciences (India)

    M Sudha Swaraga; M Adinarayana

    2003-04-01

    The rates of photooxidation of thymine in presence of peroxydisulphate (PDS) have been determined by measuring the absorbance of thymine at 264 nm spectrophotometrically. The rates and the quantum yields () of oxidation of thymine by sulphate radical anion have been determined in the presence of different concentrations of caffeic acid. Increase in [caffeic acid] is found to decrease the rate of oxidation of thymine suggesting that caffeic acid acts as an efficient scavenger of SO$^{\\bullet -}_{4}$ and protects thymine from it. Sulphate radical anion competes for thymine as well as for caffeic acid. The rate constant of sulphate radical anion with caffeic acid has been calculated to be 1.24 × 1010 dm3 mol-1 s-1. The quantum yields of photooxidation of thymine have been calculated from the rates of oxidation of thymine and the light intensity absorbed by PDS at 254 nm, the wavelength at which PDS is activated to sulphate radical anion. From the results of experimentally determined quantum yields (exptl) and the quantum yields calculated (cl) assuming caffeic acid acting only as a scavenger of SO$^{\\bullet -}_{4}$ radicals show that exptl values are lower than cl values. The ' values, which are experimentally found quantum yield values at each caffeic acid concentration and corrected for SO$^{\\bullet-}_{4}$ scavenging by caffeic acid, are also found to be greater than exptl values. These observations suggest that the thymine radicals are repaired by caffeic acid in addition to scavenging of sulphate radical anions.

  11. Bursectomy at radical gastrectomy.

    Science.gov (United States)

    Kayaalp, Cuneyt

    2015-10-27

    Radical gastrectomy with extended lymph node dissection and prophylactic resection of the omentum, peritoneum over the posterior lesser sac, pancreas and/or spleen was advocated at the beginning of the 1960s in Japan. In time, prophylactic routine resections of the pancreas and/or spleen were abandoned because of the high incidence of postoperative complications. However, omentectomy and bursectomy continued to be standard parts of traditional radical gastrectomy. The bursa omentalis was thought to be a natural barrier against invasion of cancer cells into the posterior part of the stomach. The theoretical rationale for bursectomy was to reduce the risk of peritoneal recurrences by eliminating the peritoneum over the lesser sac, which might include free cancer cells or micrometastases. Over time, the indication for bursectomy was gradually reduced to only patients with posterior gastric wall tumors penetrating the serosa. Despite its theoretical advantages, its benefit for recurrence or survival has not been proven yet. The possible reasons for this inconsistency are discussed in this review. In conclusion, the value of bursectomy in the treatment of gastric cancer is still under debate and large-scale randomized studies are necessary. Until clear evidence of patient benefit is obtained, its routine use cannot be recommended. PMID:26523213

  12. Evidence for radical-oxidation of plasma proteins in humans

    Energy Technology Data Exchange (ETDEWEB)

    Wang, D.; Davies, M.; Dean, R. [Heart Research Institute, Camperdown, NSW (Australia); Fu, S.; Taurins, A.; Sullivans, D. [Royal Prince Alfred Hospital, Camperdown, NSW (Australia). Department of Biochemistry; Muench, G. [Biozentrum der University of Wuerzberg, (Germany)

    1998-12-31

    Oxidation of proteins by radicals has been implicated in many pathological processes. The hydroxyl radical is known to generate protein-bound hydroxylated derivatives of amino acids, for example hydroxyvaline (from Val), hydroxyleucine (from Leu), o-tyrosine (from Phe), and DOPA (from Tyr). In this study, we have investigated the occurrence of these oxidised amino acids in human plasma proteins from both normal subjects and dialysis patients. By employing previously established HPLC methods [Fu et al. Biochemical Journal, 330, 233-239, 1998], we have found that oxidised amino acids exist in normal human plasma proteins (n=32). The level of these oxidised amino acids is not correlated to age. Similar levels of oxidised amino acids are found in the plasma proteins of the dialysis patients (n=6), but a more detailed survey is underway. The relative abundance of the oxidised amino acids is similar to that resulting from oxidation of BSA by hydroxy radicals or Fenton systems [Fu et al. Biochemical Journal, 333, 519-525, 1998]. The results suggest that metal-ion catalysed oxyl-radical chemistry may be a key contributor to the oxidative damage in plasma proteins in vivo in humans

  13. Evidence for radical-oxidation of plasma proteins in humans

    International Nuclear Information System (INIS)

    Oxidation of proteins by radicals has been implicated in many pathological processes. The hydroxyl radical is known to generate protein-bound hydroxylated derivatives of amino acids, for example hydroxyvaline (from Val), hydroxyleucine (from Leu), o-tyrosine (from Phe), and DOPA (from Tyr). In this study, we have investigated the occurrence of these oxidised amino acids in human plasma proteins from both normal subjects and dialysis patients. By employing previously established HPLC methods [Fu et al. Biochemical Journal, 330, 233-239, 1998], we have found that oxidised amino acids exist in normal human plasma proteins (n=32). The level of these oxidised amino acids is not correlated to age. Similar levels of oxidised amino acids are found in the plasma proteins of the dialysis patients (n=6), but a more detailed survey is underway. The relative abundance of the oxidised amino acids is similar to that resulting from oxidation of BSA by hydroxy radicals or Fenton systems [Fu et al. Biochemical Journal, 333, 519-525, 1998]. The results suggest that metal-ion catalysed oxyl-radical chemistry may be a key contributor to the oxidative damage in plasma proteins in vivo in humans

  14. Poly(ADP-ribose) polymerase inhibitor ABT-888 potentiates the cytotoxic activity of temozolomide in leukemia cells: influence of mismatch repair status and O6-methylguanine-DNA methyltransferase activity

    OpenAIRE

    Horton, Terzah M.; Jenkins, Gaye; Pati, Debananda; Zhang, Linna; Dolan, M Eileen; Ribes-Zamora, Albert; Bertuch, Alison A.; Blaney, Susan M; Delaney, Shannon L.; Hegde, Madhuri; Berg, Stacey L.

    2009-01-01

    The poly(ADP-ribose) polymerase (PARP) inhibitor ABT-888 potentiates the antitumor activity of temozolomide (TMZ). TMZ resistance results from increased O6-methylguanine-DNA methyltransferase (MGMT) activity and from mismatch repair (MMR) system mutations. We evaluated the relative importance of MGMT activity, MMR deficiency, nonhomologous end joining (NHEJ), and PARP activity in ABT-888 potentiation of TMZ. MMR-proficient and MMR-deficient leukemia cells with varying MGMT activity, as well a...

  15. The revealing of the absorption band of phenol cation-radical

    International Nuclear Information System (INIS)

    The photolysis and radiolysis of phenol in polar solutions resulted in the appearance of the bands typical of a solvated electron and phenoxy radical in the absorption spectra. At the same time no bands which could be attributed to phenol cation-radical were found. To find the region of the phenol cation-radical absorption the 77 K and room temperature absorption spectra of phenol photolysis products in a boric acid glass (1x10-3 M) have been investigated, where cation-radicals were known to be effectively stabilized. The room-temperature photolysis resulted in the appearance of the features in absorption spectrum typical of phenoxy radical in the region of 410 nm, while the 77 K photolysis lead to the formation of a photolysis with somewhat another spectrum. After refreezing the sample photolyzed at 77 K, its absorption spectrum changed to coincide completely with the phenoxy radical spectrum. Such absorption spectrum behaviour can be accounted for the phenol cation-radical formation in the glassy boric acid by the 77 K photolysis and its subsequent conversion to phenoxy radical with proton splitting by refreezing. This phenol cation-radical absorption band is situated in the region of 440-450 nm for this matrix. A similar absorption spectrum was observed by the phenol radiolysis in butyl chloride and by the anisole photolysis in orthophosphoric acid at 77 K, the facts confirming the validity of the assignment of this band to the cation-radical. (author)

  16. Spectroscopic characterization of radicals and radical pairs in fruit fly cryptochrome - protonated and nonprotonated flavin radical-states.

    Science.gov (United States)

    Paulus, Bernd; Bajzath, Csaba; Melin, Frédéric; Heidinger, Lorenz; Kromm, Viktoria; Herkersdorf, Christoph; Benz, Ulrike; Mann, Lisa; Stehle, Patricia; Hellwig, Petra; Weber, Stefan; Schleicher, Erik

    2015-08-01

    Drosophila melanogaster cryptochrome is one of the model proteins for animal blue-light photoreceptors. Using time-resolved and steady-state optical spectroscopy, we studied the mechanism of light-induced radical-pair formation and decay, and the photoreduction of the FAD cofactor. Exact kinetics on a microsecond to minutes timescale could be extracted for the wild-type protein using global analysis. The wild-type exhibits a fast photoreduction reaction from the oxidized FAD to the FAD(•-) state with a very positive midpoint potential of ~ +125 mV, although no further reduction could be observed. We could also demonstrate that the terminal tryptophan of the conserved triad, W342, is directly involved in electron transfer; however, photoreduction could not be completely inhibited in a W342F mutant. The investigation of another mutation close to the FAD cofactor, C416N, rather unexpectedly reveals accumulation of a protonated flavin radical on a timescale of several seconds. The obtained data are critically discussed with the ones obtained from another protein, Escherichia coli photolyase, and we conclude that the amino acid opposite N(5) of the isoalloxazine moiety of FAD is able to (de)stabilize the protonated FAD radical but not to significantly modulate the kinetics of any light-inducted reactions. PMID:25879256

  17. Screening tests for free radical scavengers on cutaneous cultured cells.

    Science.gov (United States)

    Noel-Hudson, M S; Cornelis, M; Lindenbaum, A; Wepierre, J

    1990-06-01

    Synopsis Numerous studies discuss the important development of free radicals in human skin after exposure to UV irradiation. They suggest that these reactive molecules are responsible for sun-accelerated cutaneous aging. We reproduced two types of radical agression on cutaneous human cell cultures. The first brings into action oxygen radicals generated by hypoxanthine-xanthine oxidase system and the second involves the use of UV radiation. These complementary models may be used as screening methods for antioxidant molecule research because they allow the distinction between molecules with filtering properties and free radical scavengers. The possibility of introducing molecules at different stages (before, during and after exposure to agression) permits the study of the molecular mecanism. These models were tested on silymarin, catechin, ascorbic acid and alpha tocopherol. PMID:19291025

  18. Characteristics of the OH radical scavenging activity of tea catechins

    International Nuclear Information System (INIS)

    Reaction rate constants of (-)-epigallocatechin gallate (EGCG) and (+)-catechin with the hydroxyl radical (·OH) were measured using the rapid flow ESR method. The rate constant of EGCG was larger twice than that of the pyrogallol or gallic acid, they are the model compounds of the B ring of EGCG. It was explained by the quantum-chemical calculation of the bond dissociation energy (BDE) of the phenolic hydroxyl group (?-OH) and the spin densities of EGCG radical. The energy of the EGCG radical was lowered by the hydrogen bonding between the radical part on the B ring and the hydroxyl group on the gallate group, leading to the lowering of BDE. Linear relationship between the relative activation energy and BDE of all the polyphenols measured was observed (Evans-Polanyi equation), showing that the reaction with ·OH occurs in the same manner. (author)

  19. Synthesis, molecular modeling and biological evaluation of novel 2-allyl amino 4-methyl sulfanyl butyric acid as ?-amylase and ?-glucosidase inhibitor

    Science.gov (United States)

    Balan, Kannan; Perumal, Perumal; Sundarabaalaji, Narayanan; Palvannan, Thayumanavan

    2015-02-01

    In the present study 2-allyl amino 4-methyl sulfanyl butyric acid (AMSB) was synthesized in good yield. AMSB was characterized by Fourier transforms infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR) (1H and 13C) and Liquid chromatography mass spectrometry (LCMS). The radical scavenging activity and reducing power assay of AMSB was assessed using 1-1-diphenyl 2-picryl hydrazyl (DPPH), 2,2?-azino-bis (3-ethyl benzothiazoline-6-sulfonic acid) (ABTS) and ferric ion reducing antioxidant power assay (FRAP) and was found to be 44.1, 34.71 and 41.7 ?g/ml respectively. The compound showed effective inhibition against ?-amylase and ?-glucosidase. AMSB was identified to be a reversible mixed noncompetitive inhibitor of ?-amylase and ?-glucosidase. The molecular docking study was carried out to evaluate the specific groove binding properties and affords valuable information of AMSB binding mode in the active site of ?-glucosidase the study may lead to the which leads to the rational design of new class of antidiabetic drugs targeting ?-glucosidase based on AMSB in near future.

  20. Pulse radiolysis of aqueous solutions of sodium azide: reactions of azide radical with tryptophan and tyrosine

    International Nuclear Information System (INIS)

    Azide radicals (N3) are formed on reactions of azide anions (N-sub(3aq)) and hydroxyl radicals in aqueous solutions. Mechanisms of formation of N3 and its reactions with the amino acids tryptophan (trpH) and tyrosine (tyrH), which gave the radicals trp and tyr, respectively, and with some inorganic transients, have been studied by use of the pulse radiolysis technique. Variation of pH has no significant effect on the formation or decay of the azide radical. Its decay rate increases with the concentration of N-sub(3aq); this is consistent with the formation of the diazide radical anion. Electron transfer reactions of N-sub(3aq) with the isopropyl radical and the dithiocyanate radical anion have been studied. The results are discussed. (author)

  1. Studies of radiation-produced radicals and radical ions

    International Nuclear Information System (INIS)

    The radiolytic oxidation of anti-5-methylbicyclo[2.1.0]pentane gives the 1-methylcyclopentene radical cation as the sole rearrangement product H migration whereas oxidation of its syn isomer results in the highly selective formation of the 3-methylcyclopentene radical cation by methyl group migration. Since exactly the same stereoselectivity of olefin formation was observed in corresponding PET (photosensitized electron transfer) studies in the liquid phase, it is concluded that the rearrangement in this case also occurs through the intermediacy of radical cations. Clearly, the radical cation rearrangement must occur very rapidly (10-8--10-9s) under liquid-phase conditions at room temperature to compete with back electron transfer, and therefore the hydrogen (or methyl) migration is a fast process under these conditions. An intramolecular cycloaddition reaction was demonstrated in the radical cation rearrangement of 4-vinylcyclohexene to bicyclo[3.2.1]oct-2-ene. ESR studies show that the radiolytic oxidation of quadricyclane in Freon matrices under conditions of high substrate dilution leads to the bicyclo[3.2.0]hepta-2,6-diene radical cation as well as the previously reported norbornadiene radical cation, the former species predominating at sufficiently low concentrations

  2. Model studies in cytochrome P-450-mediated toxicity of halogenated compounds: radical processes involving iron porphyrins.

    OpenAIRE

    Brault, D

    1985-01-01

    Haloalkane toxicity originates from attack on biological targets by reactive intermediates derived from haloalkane metabolism by a hemoprotein, cytochrome P-450. Carbon-centered radicals and their peroxyl derivatives are most likely involved. The reactions of iron porphyrin--a model for cytochrome P-450--with various carbon-centered and peroxyl radicals generated by pulse radiolysis are examined. Competition between iron porphyrin and unsaturated fatty acids for attack by peroxyl radicals is ...

  3. Antioxidant and Free Radical Scavenging Properties of Twelve Traditionally Used Indian Medicinal Plants

    OpenAIRE

    AQIL, Farrukh; AHMAD, IQBAL; MEHMOOD, Zafar

    2006-01-01

    The methanolic crude extracts of 12 traditionally used Indian medicinal plants were screened for their antioxidant and free radical scavenging properties using a-tocopherol and butylated hydroxy toluene (BHT) as standard antioxidants. Antioxidant activity was measured by ferric thiocyanate (FTC) assay and compared with the thiobarbituric acid (TBA) method. Free radical scavenging activity was evaluated using diphenyl picryl hydrazyl (DPPH) radicals. The overall antioxidant activity of Lawsoni...

  4. Screening of Various Botanical Extracts for Antioxidant Activity Using DPPH Free Radical Method

    OpenAIRE

    Waqas, Muhammad Khurram; Saqib, Najam-us; Rashid, Saeed-ur; Shah, Pervaiz Akhtar; Akhtar, Naveed; Murtaza, Ghulam

    2013-01-01

    Aiming at the exploration of herbal use by society, crude extracts of the seeds of some commonly used medicinal plants (Vitis vinifera, Tamarindus indica and Glycin max) were screened for their free radical scavenging properties using ascorbic acid as standard antioxidant. Free radical scavenging activity was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical. The overall antioxidant activity of grape seeds (Vitis vinifera) was the strongest, followed in descending order by soy...

  5. Radical Scavenging Efficacy of Thiol Capped Silver Nanoparticles

    Indian Academy of Sciences (India)

    Kumudini Chandraker; Sandeep Kumar Vaishanav; Rekha Nagwanshi; Manmohan L Satnami

    2015-12-01

    Radical scavenging efficacy of L-cysteine (L-Cys), glutathione (GSH) and thioctic acid (TA) in the presence of silver nanoparticles (AgNPs) were determined by 1,1-diphenyl 2-picryl hydrazil (DPPH), nitric oxide (NO) and hydroxyl (OH) radicals as spectrophotometric assay. The hydrogen peroxide (H2O2) scavenging efficacy has been determined by titration method. Ascorbic acid has been used as standard for all radical scavenging efficacies. In general, antioxidant activity decreases in the presence of AgNPs. The covalent interactions of thiols (-SH) were found to be a key factor for the decreases in scavenging activity. The effect of thiol concentrations has been discussed. The size and shape of the nanoparticles and AgNP-SR interactions have been characterized through Transmission Electron Microscopy (TEM) and Fourier Transform Infrared (FTIR) spectroscopy, respectively.

  6. Alkylphenol oxidation with a laccase from a white-rot fungus: effects of culture induction and of ABTS used as a mediator.

    Science.gov (United States)

    Farnet, A M; Chevremont, A C; Gil, G; Gastaldi, S; Ferre, E

    2011-01-01

    We investigated the potential of the laccase from the white-rot fungus Marasmius quercophilus to transform certain alkylphenols (p-nonylphenol, p-octylphenol and p-t-octylphenol). We tested the reactivity of this enzyme under different conditions: in liquid cultures and using the partially purified laccase with and without 2,2'-azino-bis-3-ehtylbenzothiazoline-6-sulfonicacid (ABTS) as a mediator. The percentage of p-t-octylphenol disappearance in liquid cultures was 69.0 ± 1.5% and 81 ± 5% after a 8-d or 15-d incubation, respectively, with p-nonylphenol, these percentages were 62 ± 4% and 91 ± 6% and with p-octylphenol 37 ± 3% and 65 ± 1% after a 15-d and a 21-d incubations, respectively. Induced pre-cultures were also used to inoculate the liquid cultures to enhance p-octylphenol transformation: the percentages of disappearance were 91.0 ± 0.5% and 97 ± 1% after a 8-d and a 15-d incubation, respectively. Mass spectrometry analysis showed that the products of oxidation of p-octylphenol were dimers with a mass of 411 m/z. Furthermore, we identified a purple compound (m/z 476) formed when ABTS was added to the reaction medium with the purified laccase. This result confirms that, in complex environments such as soils or litters where many molecules can interact with the enzyme substrate or the product of oxidation, laccase activities and those of other phenoloxidases should not be measured with ABTS. PMID:20980040

  7. Competitive reduction of perferrylmyoglobin radicals by protein thiols and plant phenols.

    Science.gov (United States)

    Jongberg, Sisse; Lund, Marianne N; Skibsted, Leif H; Davies, Michael J

    2014-11-19

    Radical transfer from perferrylmyoglobin to other target species (myofibrillar proteins, MPI) and bovine serum albumin (BSA), extracts from green tea (GTE), maté (ME), and rosemary (RE), and three phenolic compounds, catechin, caffeic acid, and carnosic acid) was investigated by electron paramagnetic resonance (EPR) spectroscopy to determine the concentrations of plant extracts required to protect against protein oxidation. Blocking of MPI thiol groups by N-ethylmaleimide was found to reduce the rate of reaction of MPI with perferrylmyoglobin radicals, signifying the importance of protein thiols as radical scavengers. GTE had the highest phenolic content of the three extracts and was most effective as a radical scavenger. IC50 values indicated that the molar ratio between phenols in plant extract and MPI thiols needs to be >15 in order to obtain efficient protection against protein-to-protein radical transfer in meat. Caffeic acid was found most effective among the plant phenols. PMID:25343706

  8. Radical production in biological systems

    International Nuclear Information System (INIS)

    This paper describes our effort to develop a metric for radiation exposure that is more fundamental than adsorbed dose and upon which a metric for exposure to chemicals could be based. This metric is based on the production of radicals by the two agents. Radicals produced by radiation in biological systems commonly assumed to be the same as those produced in water despite the presence of a variety of complex molecules. This may explain why the extensive efforts to describe the relationship between energy deposition (track structure) and molecular damage to DNA, based on the spectrum of radicals produced, have not been successful in explaining simple biological effects such as cell killing. Current models assume that DNA and its basic elements are immersed in water-like media and only model the production and diffusion of water-based radicals and their interaction with DNA structures; these models lack the cross sections associated with each macro-component of DNA and only treat water-based radicals. It has been found that such models are not realistic because DNA is not immersed in pure water. A computer code capable of simulating electron tracks, low-energy electrons, energy deposition in small molecules, and radical production and diffusion in water like media has been developed. This code is still in at a primitive stage and development is continuing. It is being used to study radical production by radiation, and radical diffusion and interactions in simple molecular systems following their production. We are extending the code to radical production by chemicals to complement our PBPK modeling efforts. It therefore has been developed primarily for use with radionuclides that are in biological materials, and not for radiation fields

  9. Guest Editorial: Processes of Radicalization and De-Radicalization

    Directory of Open Access Journals (Sweden)

    Donatella Della Porta

    2012-05-01

    Full Text Available The study of radicalization and de-radicalization, understood as processes leading towards the increased or decreased use of political violence, is central to the question of how political violence emerges, how it can be prevented, and how it can be contained. The focus section of this issue of the International Journal of Conflict and Violence addresses radicalization and de-radicalization, seeking to develop a more comprehensive understanding of the processes, dynamics, and mechanisms involved and taking an interdisciplinary approach to overcome the fragmentation into separate disciplines and focus areas. Contributions by Pénélope Larzillière, Felix Heiduk, Bill Kissane, Hank Johnston, Christian Davenport and Cyanne Loyle, Veronique Dudouet, and Lasse Lindekilde address repressive settings, legitimacy, institutional aspects, organizational outcomes, and dynamics in Europe, Asia, Africa, and North and South America.

  10. Borra de café colombiano (Coffea arabica) como fuente potencial de sustancias con capacidad antirradicales libres in vitro / Colombian spent coffee grounds (Coffea arabica) as a potential source of substances with free radicals capacity in vitro

    Scientific Electronic Library Online (English)

    Miguel A, Puertas-Mejía; Paola, Villegas-Guzmán; Benjamín, Alberto Rojano.

    2013-09-01

    Full Text Available Introducción: Coffea arabica L., además de su importancia comercial, también se considera una planta medicinal, porque presenta propiedades biológicas diversas, pero por su comercialización como bebida genera muchos subproductos. La borra es uno de estos, que se obtiene por la preparación de la bebi [...] da, contiene una concentración significativa de compuestos polifenólicos y, por tanto, la recuperación de estas sustancias a partir de un residuo sin valor, sería potencialmente útil para la industria farmacéutica y alimentaria. Objetivos: recuperar compuestos fenólicos a partir de la borra de café y darle un valor agregado a un residuo de origen vegetal, como fuente de componentes con capacidad antirradicales libres in vitro. Métodos: la borra de café previamente secada se sometió a extracciones sólido-líquido usando diferentes sistemas de solventes. Se evaluaron las propiedades antioxidantes in vitro usando los métodos del catión radical del ácido 2,2´-azino-bis (3-etilbenzotiazoline-6-sulfónico) y del radical 1,1-difenil-2-picrilhidracilo. Se usó cromatografía líquida de alta resolución acoplada a espectrometría de masas para la caracterizaron de los principales componentes. Resultados: todos los extractos obtenidos mostraron buena capacidad antioxidante, con el extracto de etanol:agua como el mejor, seguido del extracto de metanol acidulado. Sin embargo, la capacidad antioxidante de la fracción en diclorometano del extracto etanol:agua resultó menor que la presentada por la taza de café. Se identificaron los ácidos clorogénico, isoclorogénico y feruloilquínico como los principales componentes de la borra de café. Conclusiones: todos los extractos presentaron buena capacidad protectora contra radicales libres. La borra de café, considerada un desecho obtenido del procesamiento industrial, se puede convertir en materia prima para la recuperación de sustancias antioxidantes; lo cual genera grandes expectativas sobre su posible uso en la industria farmacéutica y alimentaria, y le da al café un valor agregado importante. Abstract in english Introduction: besides its commercial importance, Coffee arabica L. is also considered a medicinal plant due to its various biological properties, but its marketing produces a large amount of residues. Spent coffee grounds are one of these residues, which are obtained after the preparation of the dri [...] nk and contain a significant concentration of polyphenolic compounds. Therefore, the recovery of these substances costless residual will be potentially useful for food and pharmaceutical industry. Objectives: to recover polyphenolic compounds from spent coffee grounds and to give an added value to a vegetable waste as a source of substances with free radicals capacity in vitro. Methods: dehydrated spent coffee grounds were subjected to solid-liquid extraction using different solvent systems. Antioxidant properties were evaluated in vitro using the radical monocation 2,2´-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and the stable free radical 2-2-diphenyl-1-picrylhydrazyl (DPPH). Liquid chromatography coupled to mass spectrometry was applied to characterize the main compounds. Results: all the extracts obtained showed a good antioxidant capacity with ethanol-water extract, followed by acidulated methanol extract. However, the antioxidant capacity of the ethanol-water extract was lower than coffee beverage. Chlorogenic, isochlorogenic and feruloylquinic acids were identified as the main compounds present in spent coffee grounds. Conclusions: all extracts showed a significant protection effect against free radicals; spent coffee ground, which is considered an undesirable solid waste from industrial processing, could be an add-value raw material in the recovery of antioxidant substances which generates great expectations about its possible use in the pharmaceutical and food industry and gives coffee an important added value.

  11. Hydroxyl radical induced degradation of salicylates in aerated aqueous solution

    Science.gov (United States)

    Szabó, László; Tóth, Tünde; Homlok, Renáta; Rácz, Gergely; Takács, Erzsébet; Wojnárovits, László

    2014-04-01

    Ionizing radiation induced degradation of acetylsalicylic acid, its hydrolysis product salicylic acid and a salicylic acid derivative 5-sulpho-salicylic acid, was investigated in dilute aqueous solutions by UV-vis spectrophotometry, HPLC separation and diode-array or MS/MS detection, chemical oxygen demand, total organic carbon content and by Vibrio fischeri toxicity measurements. Hydroxyl radicals were shown to degrade these molecules readily, and first degradation products were hydroxylated derivatives in all cases. Due to the by-products, among them hydrogen peroxide, the toxicity first increased and then decreased with the absorbed dose. With prolonged irradiation complete mineralization was achieved.

  12. Free-radical polymerization of some dental and medical materials by pulse radiolysis

    International Nuclear Information System (INIS)

    Complete text of publication follows. The extensive use of N-P-tolylglycine (NPG) analogues in adhesive bonding technologies calls for a better understanding of their role in initiating free-radical polymerization. The fast oxidation and reductions of NTG proceed via the formation of various types of free radicals and radical cation and anion intermediates. These intermediates were identified and their reactivity with oxygen, to produce the corresponding peroxyl radicals, has been measured. Hydroxyl radicals (OH) were used to initiate oxidation reactions of NTG, while the reduction reactions were initiated with hydrated electrons (eaq-). In the presence and absence of oxygen, the oxidation reaction mechanism of NTG by OH proceeded predominately by addition to the aromatic ring followed by OH- elimination reactions to produce NTG+ radical cations. In the presence of oxygen, OH-NTG also reacted with oxygen to produce peroxyl radicals. The reduction reaction of NTG with eaq- proceed via addition to the aromatic ring and amine-elimination, to produce various radicals: addition to the aromatic ring was followed by a fast protonation reaction to produce cyclohexadienyl radicals, and the amine-elimination reaction produced acetic acid free radicals and 4-methylaniline. In addition, it was found that the H-atom reaction with NTG also produced radical cations

  13. Energetics of reactions of O-sub(aq) and of O--transfer reactions between radicals

    International Nuclear Information System (INIS)

    Free energies of formation of various free radicals such as O-sub(aq), CO-sub(3aq), CO-sub(2aq), and X-sub(2aq) (X = Cl, Br and I) have been derived and used to calculate standard potentials of radicals and free energies of their reactions. O-sub(aq) is an oxidizing radical with a potential E0(O-sub(aq) + H2O/2OH-sub(aq)) = 1.9 V, i.e. electron pick-up is accompanied by simultaneous breakage of a water molecule in the hydration shell. Water is also decomposed in the reaction between two O-sub(aq) radicals, HO2- + OH- being much more probable products than O + 2OH-. O-sub(aq) is almost as strong a hydrogen atom abstracting radical as the hydroxyl radical. CO-sub(3aq) can donate O- to various radicals. These reactions may occur directly or via a complex that hydrolyses. O--transfer occurs in competition with electron transfer from the substrate radical to CO-sub(3aq). Transfer of O- from CO-sub(2aq) or HCOsub(3aq) radicals to form carbon monoxide is strongly exoergic. The formation of CO in the radiolysis of acid solutions of formate is explained by O--transfer between the intermediate radicals. O--transfer from a radical to an electrode is also considered. (author)

  14. CONTINENT RADICAL PROSTATECTOMY

    Directory of Open Access Journals (Sweden)

    Yu. P. Sernyak

    2014-07-01

    Full Text Available Objective: to evaluate the impact of dissection of the dorsal venous complex without pre-ligation, suturing, or coagulation during radical prostatectomy (RPE in patients with localized prostate cancer (PC on the quality of surgery and the function of urinary retention.Subjects and methods. The data of 42 patients who had undergone posterior and anterior anatomical repair and vesicourethral anastomosis using a V-lock suture after prostatectomy were analyzed. All the patients were divided into 2 groups. Group 1 consisted of 22 patients in whom the dorsal venous complex was closed using a 3-0 vicryl suture before urethral dissection. Group 2 included 20 patients in whom the urethra was dissected without suturing the venous complex.Results. In group 1, complete urinary retention after catheter removal was noted in 9 (40.9 % and 15 (68 % patients within 24 hours and after 3 months, respectively. Following 12 months, two (9 % patients were observed to have partial mild urinary incontinence (as many as 2 pads per day. Group 2 patients showed complete urinary retention in 17 (85 % cases on the first day after catheter removal; all the patients retained urine 3 months later.Conclusion. In patients with localized PC, dissection of the dorsal venous complex without presuturing during laparoscopic RPE exerts a considerable impact on the preservation of urinary retention, namely 45% more of the patients reported complete urinary retention in early periods and 10 % more did this in later periods. At the same time, there was no statistically significant increase in intraoperative blood loss (p > 0.05, the number of positive edges, or biochemical recurrences.

  15. Free radicals in the aqueous humor of patients with glaucoma

    Directory of Open Access Journals (Sweden)

    Eiki Oshida

    2010-06-01

    Full Text Available Eiki Oshida, Yukihiro Matsumoto, Kiyomi Arai1Department of Ophthalmology, Dokkyo Medical University Koshigaya Hospital, Koshigaya, Saitama, JapanPurpose: To clarify the presence of oxidative stress in glaucoma and discuss whether free radicals contribute to neovascular glaucoma (NVG and non-NVG.Methods: Two patient groups were formed: the NVG group (n = 10 and the non-NVG group (n = 17. Free radicals in aqueous humor were detected by measuring the electron spin resonance (ESR. To identify free radical species, either superoxide dismutase (SOD or catalase was added to the aqueous humor and compared with aqueous humor in which SOD or catalase was not added.Results: In the NVG group, free radical waveforms were detected that differed from ascorbate-free radical (AFR in all cases. Under SOD was added, the characteristic waveforms disappeared and the AFR of a specific waveform appeared. After catalase was added, the waveforms were unchanged. In the non-NVG group, the AFR of specific waveforms were detected in all cases. In 4 cases, the waveforms detected the presence of a trace of superoxide.Conclusions: In the NVG group, superoxides were detected, suggesting that superoxide scavenging activity was decreased markedly. L-ascorbic acid likely has an antioxidative function in the non-NVG group, suggesting that the aqueous humor in the NVG group was under higher oxidative stress compared with the non-NVG group.Keywords: oxidative stress, free radicals, glaucoma, ascorbate

  16. Switching radical stability by pH-induced orbital conversion.

    Science.gov (United States)

    Gryn'ova, Ganna; Marshall, David L; Blanksby, Stephen J; Coote, Michelle L

    2013-06-01

    In most radicals the singly occupied molecular orbital (SOMO) is the highest-energy occupied molecular orbital (HOMO); however, in a small number of reported compounds this is not the case. In the present work we expand significantly the scope of this phenomenon, known as SOMO-HOMO energy-level conversion, by showing that it occurs in virtually any distonic radical anion that contains a sufficiently stabilized radical (aminoxyl, peroxyl, aminyl) non-?-conjugated with a negative charge (carboxylate, phosphate, sulfate). Moreover, regular orbital order is restored on protonation of the anionic fragment, and hence the orbital configuration can be switched by pH. Most importantly, our theoretical and experimental results reveal a dramatically higher radical stability and proton acidity of such distonic radical anions. Changing radical stability by 3-4 orders of magnitude using pH-induced orbital conversion opens a variety of attractive industrial applications, including pH-switchable nitroxide-mediated polymerization, and it might be exploited in nature. PMID:23695628

  17. Thermochemistry of alkyl free radicals

    International Nuclear Information System (INIS)

    The group additivity difference method is used to estimate the thermochemical properties (Cp0(T), 298 0298, ?fH0298) of alkyl free radicals from ethyl through the C6 radicals. Revised values are calculated for the alkyl radical groups. Recent experimental and theoretical work on hindered rotor barrier heights necessitating these revised calculations is discussed. All Cp's are also expressed in polynomial form, Cp0(T) = a1 + a2T + a3T2 + a4T3. Polynomial coefficients are given for the calculation of the equilibrium constants for formation of the radicals from the elements: nC + 1/2(2n + 1)H2 ? CnH2n+1. 35 refs., 12 tabs

  18. Urogynaecological dysfunction after radical hysterectomy

    DEFF Research Database (Denmark)

    Axelsen, S M; Petersen, L K; Axelsen, Susanne Maigaard

    2006-01-01

    AIMS: To identify self-reported urogynaecological dysfunctions in women treated by radical hysterectomy, and predict risk factors. METHODS: A survey using questionnaires. Questionnaires were mailed to 396 patients. RESULTS: Symptoms of urinary incontinence and urinary retention were reported by...

  19. The role of the acidity of N-heteroaryl sulfonamides as inhibitors of bcl-2 family protein-protein interactions.

    Science.gov (United States)

    Touré, B Barry; Miller-Moslin, Karen; Yusuff, Naeem; Perez, Lawrence; Doré, Michael; Joud, Carol; Michael, Walter; DiPietro, Lucian; van der Plas, Simon; McEwan, Michael; Lenoir, Francois; Hoe, Madelene; Karki, Rajesh; Springer, Clayton; Sullivan, John; Levine, Kymberly; Fiorilla, Catherine; Xie, Xiaoling; Kulathila, Raviraj; Herlihy, Kara; Porter, Dale; Visser, Michael

    2013-02-14

    Overexpression of the antiapoptotic members of the Bcl-2 family of proteins is commonly associated with cancer cell survival and resistance to chemotherapeutics. Here, we describe the structure-based optimization of a series of N-heteroaryl sulfonamides that demonstrate potent mechanism-based cell death. The role of the acidic nature of the sulfonamide moiety as it relates to potency, solubility, and clearance is examined. This has led to the discovery of novel heterocyclic replacements for the acylsulfonamide core of ABT-737 and ABT-263. PMID:24900652

  20. Radical Innovation and Network Evolution

    OpenAIRE

    Phlippen, Sandra; Riccaboni, M.

    2007-01-01

    This paper examines how a radical technological innovation affects alliance formation of firms and subsequent network structures. We use longitudinal data of interfirm R&D collaborations in the biopharmaceutical industry in which a new technological regime is established. Our findings suggest that it requires radical technological change for firms to leave their embedded path of existing alliances and form new alliances with new partners. While new partners are mostly found through the firms’...

  1. Muon investigations of fullerenyl radicals

    International Nuclear Information System (INIS)

    Four of the five possible isomeric C70Mu radicals have been detected by transverse-field ?SR in a C70 powder sample at 298K. Their assignment is based on the results of semi-empirical MNDO calculations. There are significant changes in intensity and lineshape of the signals at low temperature. The first ?SR spectrum of a fullerenyl radical in solution has been obtained. (orig.)

  2. Radical prostatectomy. Results and indications

    International Nuclear Information System (INIS)

    Radical prostatectomy is the surgical curative treatment of localized prostate cancer. The survival is good in young patients (<70) with T2 N0M0 tumors and more than 10 year's life expectancy. Side-effects are urinary incontinence, impotence and anastomosis stricture. Quality of life should be considered as an important factor for the choice of the patient between radical prostatectomy, radiotherapy and follow-up. (author)

  3. Bioactive caffeic acid esters from Glycyrrhiza glabra.

    Science.gov (United States)

    Dey, Surajit; Deepak, Mundkinajeddu; Setty, Manjunath; D'Souza, Prashanth; Agarwal, Amit; Sangli, Gopal Krishna

    2009-01-01

    Thin layer chromatography bioautography (using DPPH spray reagent) guided fractionation of Glycyrrhiza glabra led to the isolation of two caffeic acid derivative esters, viz. eicosanyl caffeate (1) and docosyl caffeate (2). The two compounds exhibited potent elastase inhibitory activity, with IC(50) values of 0.99 microg mL(-1) and 1.4 microg mL(-1) for 1 and 2, respectively. The compounds also showed moderate antioxidant activity in DPPH and ABTS scavenging assays. The results indicate a possible role of caffeic acid derivatives, in addition to flavonoids in the anti-ulcer properties of G. glabra. PMID:19921583

  4. Exploring the Theories of Radicalization

    Directory of Open Access Journals (Sweden)

    Maskali?nait? Asta

    2015-12-01

    Full Text Available After the London bombings in July 2005, the concern of terrorism scholars and policy makers has turned to “home-grown” terrorism and potential for political violence from within the states. “Radicalization” became a new buzz word. This article follows a number of reviews of the literature on radicalization and offers another angle for looking at this research. First, it discusses the term “radicalization” and suggests the use of the following definition of radicalization as a process by which a person adopts belief systems which justify the use of violence to effect social change and comes to actively support as well as employ violent means for political purposes. Next, it proposes to see the theories of radicalization focusing on the individual and the two dimensions of his/her motivation: whether that motivation is internal or external and whether it is due to personal choice or either internal (due to some psychological traits or external compulsion. Though not all theories fall neatly within these categories, they make it possible to make comparisons of contributions from a variety of different areas thus reflecting on the interdisciplinary nature of the study of terrorism in general and radicalization as a part of it.

  5. The poly(ADP-Ribose) polymerase inhibitor ABT-888 reduces radiation-induced nuclear EGFR and augments head and neck tumor response to radiotherapy

    International Nuclear Information System (INIS)

    Background and purpose: Current therapies for head and neck cancer frequently are not curative, necessitating novel therapeutic strategies. Thus, we studied whether inhibition of poly(ADP-Ribose) polymerase (PARP), a key DNA repair enzyme, could improve efficacy of radiotherapy in human head and neck cancer. Materials and methods: UM-SCC1, UM-SCC5, UM-SCC6, and FaDu human head and neck cancer cellular susceptibility to the PARP inhibitor (PARPi) ABT-888 and/or radiation (IR) was assessed using colony formation assays. DNA damage was evaluated using the alkaline comet assay and immunostaining for ?-H2AX foci. Non-homologous end-joining (NHEJ) mediated repair was measured using phospho-DNA-Pk foci. Epidermal growth factor receptor (EGFR) location was assessed by immunostaining. Poly ADP-Ribose polymerization (PAR) levels were assessed using immunoblotting. Results: Human head and neck cancer cells exhibited enhanced cytotoxicity with IR and ABT-888 compared to either agent alone. This increased susceptibility correlated with reduced nuclear EGFR, attenuation of NHEJ, and persistence of DNA damage following IR. Interestingly, a subset of head and neck cancer cells which had elevated basal PAR levels was susceptible to PARPi alone. Conclusions: Combining radiotherapy and PARP inhibition may improve outcomes and quality of life for head and neck cancer patients treated with radiotherapy. Furthermore, this novel strategy may also be feasible in other tumor types. Moreover, PAR levels should be investigated as a potential biomarker for tumor susceptibility to PARP inhibition.

  6. Mechanistic studies of the atmospheric oxidation of methyl butenol by OH radicals, ozone and NO 3 radicals

    Science.gov (United States)

    Fantechi, G.; Jensen, N. R.; Hjorth, J.; Peeters, J.

    In a recent field study, strong indications have been obtained that 2-methyl-3-buten-2-ol (methyl butenol, MBO) is a compound emitted in important quantities by some types of vegetation. The atmospheric oxidation products from MBO are not yet well known. In this investigation we studied the reaction mechanisms and products of the reaction of MBO with OH radicals, O 3 and NO 3 radicals. All the experiments were performed in a 480 ? Teflon coated Pyrex glass chamber equipped with a long path length FTIR spectrometer. As products from the reaction between MBO and OH we identified and quantified acetone, glycolaldehyde, formaldehyde, formic acid, CO and CO 2. From the reaction between MBO and O 3, the products acetone, formaldehyde, formic acid, CO and CO 2 have been identified; also, 2-hydroxy-2-methyl-propanal (HMPR) is tentatively put forward as a product on the basis of HPLC and GC-MS analysis of the DNPH derivative. Organic nitrates, peroxynitrates and carbonyl nitrates, together with acetone were observed as products of the reaction between MBO and the nitrate radical. Tentative reaction mechanisms for the oxidation of MBO by OH radicals, O 3 and NO 3 radicals are proposed.

  7. FREE RADICAL SCAVENGING, IMMUNOMODULATORY ACTIVITY AND CHEMICAL COMPOSITION OF LUFFA ACUTANGULA VAR: AMARA (CUCURBITACEAE) PERICARP

    Scientific Electronic Library Online (English)

    KALASKAR, MOHAN G.; SURANA, SANJAY J..

    2014-03-01

    Full Text Available The Luffa acutangula Var. amara (Cucurbitaceae) is climbing shrub; commonly known as wild ridge gourd. Its aerial parts are used traditionally in diverse health ailments. Four successive extracts of L. amara pericarp (LAP) were evaluated for antioxidant using in vitro for DPPH, ABTS, superoxides rad [...] ical, reducing power and phosphomolybdenum assay. The bioactive ethanol extract was evaluated for immunomodulatory activity by in vivo phagocytosis using carbon clearance and neutrophil adhesion test. The bioactive ethanolic extracts showed potent in vitro antioxidant ability, increased phagocytic index (0.028 ± 0.002), and increased the % neutrophil adhesion (24.63 ± 0.87%). Furthermore, the potent plant phenolics such as gallic acid and p-hydroxybenzoic acid were isolated and identified spectroscopically. The presence of these plant phenolics and like constituents would be responsible for their potent antioxidant and immunomodulatory activity.

  8. Free radicals from purine nucleosides after hydroxyl radical attack

    International Nuclear Information System (INIS)

    Free radicals from imidazole, caffeine, guanosine, deoxyguanosine, inosine, adenosine, deoxyadenosine, and adenine, as well as ?-D-ribose and ?-D-deoxyribose, were generated by reaction with OH from H2O2--Ti3+ at pH 1.5-2 and studied by ESR, using a computerized, Q-band, fast-flow system. Purine base radicals, plus sugar radicals in nucleosides, were always observed. Prior deuteration of C8 made possible the assignment of the observed 10--15 gauss doublet splitting to the C8 proton in guanine derivatives, and to the C2 proton in adenine derivatives and inosine. Hueckel calculations (and INDO in a few cases) on possible radical species suggest that hydroxyl addition on nitrogens in the purine ring or on C5 may be responsible for the species which are observed. In imidazole, the radical species is a hydroxyl adduct. An anomalous effect of deuteration of CS on the spectrum obtained with caffeine is also reported

  9. Chemopreventive effect of cactus (Opuntia humifusa) extracts: radical scavenging activity, pro-apoptosis, and anti-inflammatory effect in human colon (SW480) and breast cancer (MCF7) cells.

    Science.gov (United States)

    Kim, Jinhee; Jho, Kwang Hyun; Choi, Young Hee; Nam, Sang-Yong

    2013-04-30

    Cactus (Opuntia spp) is widely cultivated as a vegetable, fruit, and forage crop and has been used in traditional medicine in American Indian, Mexican, and Korean cultures. Accumulative evidence from both in vitro and in vivo studies using cacti suggests their biological and pharmacological activities, such as their anti-cancer and anti-inflammatory roles in different cancer cells. In this study, the Opuntia humifusa stem (OHS) was extracted with different solvents and screened for radical scavenging activity using 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS?(+)) and 1,1-diphenyl-2-picryl hydrazyl (DPPH). In addition, the total phenolic and flavonoid contents of each extract were analyzed using the Folin-Ciocalteu method and high performance liquid chromatography, respectively. Further, the cacti's bioactive fractions were evaluated for cell cytotoxicity and to understand their mechanism of action on human colon cancer (SW480) and breast cancer (MCF7) cells. An ethyl acetate (EtOAc) extract exhibited the highest cytotoxicity and resulted in an up-regulated expression of the pro-apoptotic protein Bax (bcl-2 associated X protein) and a down-regulated expression of the anti-apoptotic protein Bcl2 in both SW480 and MCF7 cells. The apoptosis was mediated through activation of caspase 8, 9, and 3/7 activities as well as PARP cleavage in SW480 cells, while the same extract activated only a caspase 9 activity in MCF7 cells. Furthermore, incubation of cells with the EtOAc extract down-regulated the expression of inflammatory molecules such as cyclooxygenase-2 (COX2) and inducible nitric oxide synthase (iNOS) in SW480 cells but not in MCF7 cells. Taken together, these results suggest that SW480 colon cancer cells are more susceptible to bioactive compounds present in OHS and may have potential in the prevention of cancer through modulation of apoptosis markers and inhibition of inflammatory pathways. PMID:23435602

  10. Crystalline bipyridinium radical complexes and uses thereof

    Energy Technology Data Exchange (ETDEWEB)

    Fahrenbach, Albert C.; Barnes, Jonathan C.; Li, Hao; Stoddart, J. Fraser; Basuray, Ashish Neil; Sampath, Srinivasan

    2015-09-01

    Described herein are methods of generating 4,4'-bipyridinium radical cations (BIPY.sup..cndot.+), and methods for utilizing the radical-radical interactions between two or more BIPY.sup..cndot.+ radical cations that ensue for the creation of novel materials for applications in nanotechnology. Synthetic methodologies, crystallographic engineering techniques, methods of physical characterization, and end uses are described.

  11. Crystalline bipyridinium radical complexes and uses thereof

    Science.gov (United States)

    Fahrenbach, Albert C.; Barnes, Jonathan C.; Li, Hao; Stoddart, J. Fraser; Basuray, Ashish Neil; Sampath, Srinivasan

    2015-09-01

    Described herein are methods of generating 4,4'-bipyridinium radical cations (BIPY.sup..cndot.+), and methods for utilizing the radical-radical interactions between two or more BIPY.sup..cndot.+ radical cations that ensue for the creation of novel materials for applications in nanotechnology. Synthetic methodologies, crystallographic engineering techniques, methods of physical characterization, and end uses are described.

  12. Formation of bromate in sulfate radical based oxidation: mechanistic aspects and suppression by dissolved organic matter.

    Science.gov (United States)

    Lutze, Holger V; Bakkour, Rani; Kerlin, Nils; von Sonntag, Clemens; Schmidt, Torsten C

    2014-04-15

    Sulfate radical based oxidation is discussed being a potential alternative to hydroxyl radical based oxidation for pollutant control in water treatment. However, formation of undesired by-products, has hardly been addressed in the current literature, which is an issue in other oxidative processes such as bromate formation in ozonation of bromide containing water (US-EPA and EU drinking water standard of bromate: 10 ?g L(-1)). Sulfate radicals react fast with bromide (k = 3.5 × 10(9) M(-1) s(-1)) which could also yield bromate as final product. The mechanism of bromate formation in aqueous solution in presence of sulfate radicals has been investigated in the present paper. Further experiments were performed in presence of humic acids and in surface water for investigating the relevance of bromate formation in context of pollutant control. The formation of bromate by sulfate radicals resembles the well described mechanism of the hydroxyl radical based bromate formation. In both cases hypobromous acid is a requisite intermediate. In presence of organic matter formation of bromate is effectively suppressed. That can be explained by formation of superoxide formed in the reaction of sulfate radicals plus aromatic moieties of organic matter, since superoxide reduces hypobromous acid yielding bromine atoms and bromide. Hence formation of bromate can be neglected in sulfate radical based oxidation at typical conditions of water treatment. PMID:24565691

  13. Acetate peroxyl radicals, sup(.)O2CH2CO2-

    International Nuclear Information System (INIS)

    Hydroxyl radicals from the radiolysis of N2O/O2 (4:1 v/v)-saturated aqueous solutions have been reacted with acetate ions (10-2 M). As measured by pulse radiolysis, the resulting sup(.)CH2CO2- radicals react with oxygen yielding the corresponding peroxyl radicals, sup(.)O2CH2CO2- (k = 1.7 x 109 M-1s-1). These peroxyl radicals decay bimolecularly (2k = 1.5 x 108 M-1s-1) giving rise to the products (G values in brackets) glyoxylic acid (2.7), glycolic acid (0.7), formaldehyde (1.4), carbon dioxide (1.4), organic hydroperoxide (0.7) and hydrogen peroxide (2.5). Oxygen is consumed with a G value of 5.3. Aided by data from pulse radiolysis it is concluded that the intermediate tetroxide formed upon the bimolecular decay breaks down by various routes to yield: (i) hydrogen peroxide and two molecules of glyoxylic acid (ca. 27%); (ii) oxygen, glycolic acid and glyoxylic acid (ca. 25%); (iii) hydrogen peroxide and two molecules of formaldehyde, carbon dioxide and OH- (25%). These reactions do not involve free radicals as intermediates; (iv) There is some O2- (G proportional 0.5) formed in the decay of the peroxyl radicals, which is attributed to the decay of intermediate oxyl radicals (tetroxide -> O2 + 2 sup(.)OCH2CO2-) by 1,2-H shift, oxygen addition and HO2sup(.) elimination, a reaction sequence which gives rise to glyoxylic acid (10%); (v) The reaction of O2- with the organic peroxyl radical yields the hydroperoxide (13%). Reaction (iii) is a novel peroxyl radical reaction. (orig.)

  14. Formation and reactions of radical cations of substituted benzenes in aqueous media

    International Nuclear Information System (INIS)

    Radical cations of anisole, methylated benzenes, ethylbenzene, isopropylbenzene, tert-butylbenzene and N,N-dimethylaniline were studied in aqueous media by pulse radiolytic technique. Absorption spectra and reaction kinetics of the radical cations were recorded. The radical cations are formed from the corresponding OH adducts by the elimination of OH-, either by a simple dissociation or by an acid catalyzed reaction. The rate constants of the formation of the radical cations and their reactions with water, OH- and Fe2+, or the reaction of a proton loss, were measured. The rate constants for the reaction with water and OH-, together with the rate constants for the dissociation of the OH adducts, are correlated with the ionization potential of the parent compound. These correlations offer a possibility of predicting the acid-base properties of radical cations of substituted benzenes, or the estimation of their ionization potential. (author)

  15. In Vitro Antioxidant and free Radical Scavenging activity of the Ethanolic extract of Aesculus hippocastanum

    Directory of Open Access Journals (Sweden)

    R. V. Geetha

    2013-09-01

    Full Text Available The aim of the present study was to evaluate the antioxidant and free radical scavenging activity of the ethanolic extract of Aesculus hippocastanum (Horse chest nut. Highly reactive free radicals and oxygen species are present in biological systems from a wide variety of sources. These free radicals may oxidize nucleic acids, proteins, lipids or DNA and can initiate degenerative disease. Antioxidants play an important role in protecting cellular damage caused by reactive oxygen species. Plants containing phenolic compounds have been reported to possess strong antioxidant properties. Antioxidant potential of the ethanolic extract of Aesculus hippocastanum was studied using different in vitro free radical scavenging models like DPPH and Hydrogen Peroxide. The DPPH results have been compared with the standard Ascorbic acid .The extract showed good dose dependent free radical scavenging property in both the models used in this study.

  16. Peroxy radical partitioning during the AMMA radical intercomparison exercise

    Directory of Open Access Journals (Sweden)

    M. D. Andrés-Hernández

    2010-11-01

    Full Text Available Peroxy radicals were measured onboard two scientific aircrafts during the AMMA (African Monsoon Multidisciplinary Analysis campaign in summer 2006. This paper reports results from the flight on 16 August 2006 during which measurements of HO2 by laser induced fluorescence spectroscopy at low pressure (LIF-FAGE and total peroxy radicals (RO2* = HO2+?RO2, R = organic chain by two similar instruments based on the peroxy radical chemical amplification (PeRCA technique were subject of a blind intercomparison. The German DLR-Falcon and the British FAAM-BAe-146 flew wing tip to wing tip for about 30 min making concurrent measurements on 2 horizontal level runs at 697 and 485 hPa over the same geographical area in Burkina Faso. A full set of supporting measurements comprising photolysis frequencies, and relevant trace gases like CO, NO, NO2, NOy, O3 and a wider range of VOCs were collected simultaneously.

    Results are discussed on the basis of the characteristics and limitations of the different instruments used. Generally, no data bias are identified and the RO2* data available agree quite reasonably within the instrumental errors. The [RO2*]/[HO2] ratios, which vary between 1:1 and 3:1, as well as the peroxy radical variability, concur with variations in photolysis rates and in other potential radical precursors. Model results provide additional information about dominant radical formation and loss processes.

  17. Peroxy radical partitioning during the AMMA radical intercomparison exercise

    Directory of Open Access Journals (Sweden)

    M. D. Andrés-Hernández

    2010-04-01

    Full Text Available Peroxy radicals were measured onboard two scientific aircrafts during the AMMA (African Monsoon Multidisciplinary Analysis campaign in summer 2006. This paper reports results from the flight on 16 August 2006 during which measurements of HO2 by laser induced fluorescence spectroscopy at low pressure (LIF-FAGE and total peroxy radicals (RO2*=HO2+ΣRO2, R= organic chain by two similar instruments based on the peroxy radical chemical amplification (PerCA technique were subject of a blind intercomparison. The German DLR-Falcon and the British FAAM-BAe-146 flew wing tip to wing tip for about 30 min making concurrent measurements on 2 horizontal level runs at 697 and 485 hPa over the same geographical area in Burkina Faso. A full set of supporting measurements comprising photolysis frequencies, and relevant trace gases like CO, NO, NO2, NOy, O3 and a wider range of VOCs were collected simultaneously.

    Results are discussed on the basis of the characteristics and limitations of the different instruments used. Generally, no data bias are identified and the RO2* data available agree quite reasonably within the instrumental errors. The [RO2*]/[HO2] ratios, which vary between 1:1 and 3:1, as well as the peroxy radical variability, concur with variations in photolysis rates and in other potential radical precursors. Model results provide additional information about dominant radical formation and loss processes.

  18. Hydroxyl radical, sulfate radical and nitrate radical reactivity towards crown ethers in aqueous solutions

    International Nuclear Information System (INIS)

    Reaction rate constants of crown ethers (12-crown-4, 15-crown-5, 18-crown-6) and their analogs 1,4-dioxane (6C2) with some important oxidative radicals, hydroxyl radical (·OH), sulfate radical (SO4·?) and nitrate radical (NO3·), were determined in various aqueous solutions by pulse radiolysis and laser photolysis techniques. The reaction rate constants for 6C2 and crown ethers with ·OH and SO4·? increase with the number of hydrogen atoms in the ethers, indicating that the hydrogen-atom abstraction is a dominant reaction between crown ethers and these two radicals. The presence of cations in solution has negligible effect on the rate constants of crown ether towards ·OH and SO4·?. However, for the NO3·, the rate constants are not proportional to the number of hydrogen atoms in ethers, and 12-crown-4 (12C4) is the most reactive compared with other crown ethers. Except 12C4 and 6C2, the cations in the aqueous solution affect the reactivities of 15-crown-5 (15C5) and 18-crown-6 (18C6). The cations with high binding stability for crown ether would improve the reactivity of 15C5. For the studied crown ethers, the reaction rate constants of these oxidative radicals have the order ·OH>SO4·?>NO3·. Furthermore, the formation of radicals after the reaction of crown ethers with sulfate radical could be observed in the range of 260–280 nm using laser photolysis and pulse radiolysis. This is the first report on the kinetic behavior of crown ethers with NO3·, and it would be helpful for the understanding of stability of crown ethers in the processing of spent nuclear fuel. - Highlights: ? The rate constants of NO3· and SO4·? towards various crown ethers in aqueous solution were determined for the first time. ? The rate constants of these radicals towards crown ethers have the order ·OH>SO4·?>NO3·. ? Hydrogen atom abstraction is the dominant reaction between these radicals and crown ethers. ? The binding capacity of crown ethers with cations in solution will affect k (NO3·+ ethers).

  19. Is Kant’s conception of radical evil radical enough

    Directory of Open Access Journals (Sweden)

    Loli? Marinko

    2011-01-01

    Full Text Available Kant’s philosophical critical attitudes provoked strong reactions, not only philosophical, but the general public. Among those of his ideas, which have been provoking severe philosophical misunderstandings and controversy are: “Which in theory is not worth, that has no use in practice”, “The rights not to lie”, “against the rights of citizens to revolt”, etc. After all, the most attention in the great public was provoked by his idea about radical evil. In this short reflection, we will try to point out the main points of this philosophical misunderstanding and to make a little more explicit the concept of radical evil.

  20. Global radicals : Caribbean radical thought 1920-1983

    OpenAIRE

    Révauger, Jean-Paul

    2013-01-01

    This chapter explores the development of radical thought in the Caribbean, from the 1920’s until the American invasion of Grenada in 1983. The thrust of the argument is that radical thinkers had a global outlook, and not a nationalistic parochial one. They were aware of world debates and included within the international movements of their time. George Padmore is a case in point. An agent of the Communist International in the USSR and Germany, he fell foul with communism and became a Pan Afri...

  1. The production of OH radicals in the radiolysis of water with 4He ions

    International Nuclear Information System (INIS)

    Formic acid solutions of 1, 10, 100, and 1000 mM have been irradiated with 4He ions of 5 to 25 MeV, and the production of OH radicals has been determined by measuring the yield of CO2. The differential OH radical yields were obtained from the observed energy dependencies; with 25 MeV 4He ions they range from 1.91 to 3.48 molecules/100 eV for formic acid concentrations of 1 to 1000 mM, respectively. The OH radical yields decrease with decreasing particle energy, and at the maximum LET (230 eV/nm) they range from 0.30 at 1 mM to 0.82 molecules/100 eV at 1000 mM. These values are only 15 to 20% of that found with fast electrons. The OH radical yields are relatively more dependent on formic acid concentration at higher 4He ion energies. The average time dependencies of the OH radical from 7.7 ns to 7.7 microseconds were estimated from the formic acid concentration dependencies at various 4He energies. In terms of absolute yields, there is a considerable variation in the yields of OH radicals with time at the highest energies, but at the maximum LET the OH radical yields are nearly invariant with time after about 10 ns

  2. The tricarbonylchromium template for stereocontrol in radical reactions of arenes.

    Science.gov (United States)

    Merlic, C A; Walsh, J C

    2001-04-01

    Chromium tricarbonyl complexed aryl aldeyhydes and ketones underwent Sm(II)-promoted radical lactone formation in the presence of alpha,beta-unsaturated esters to produce diastereomerically pure lactones in good yields. The completely diastereoselective lactone formation involves capture of the benzylic ketyl radical by the ester anti to the chromium tricarbonyl moiety. The relative stereochemistry of the lactone and chromium tricarbonyl moieties was proven by X-ray crystallography and supports the proposed mechanism. Enantiopure chromium tricarbonyl complexed arenes afforded single enantiomers when subjected to Sm(II)-promoted radical lactone formation condiditions. The enantio- and diastereomerically pure chromium tricarbonyl complexed lactones were subsequently treated with BF3.OEt2 to generate a mixture of diastereomers via Lewis acid promoted chromium tricabonyl directed cationic rearrangement. The diastereomers were separated and individually decomplexed with I2 to afford both of the corresponding chromium-free enantiomerically pure lactones starting from a single enantiomerically pure chromium tricarbonyl complex. PMID:11281765

  3. Photoionization of the OH radical

    International Nuclear Information System (INIS)

    The hydroxyl radical (OH) is one of the most thoroughly studied free radicals because of its importance in atmospheric chemistry, combustion processes, and the interstellar medium. Detailed experimental and theoretical studies have been performed on the ground electronic state (X 2PI/sub i/) and on the four lowest bound excited electronic states (A 2?+, B 2?+, D 2?-, and C2?+). However, because it is difficult to distinguish the spectrum of OH from the spectra of the various radical precursors, the absorption spectrum in the wavelength region below 1200 A has not been well characterized. In the present work, the spectrum of OH has been determined in the wavelength region from 750 to 950 A using the technique of photoionization mass spectrometry. This technique allows complete separation of the spectrum of OH from that of the other components of the discharge and permits the unambiguous determination of the spectrum of OH

  4. Salvage radiotherapy following radical prostatectomy

    International Nuclear Information System (INIS)

    Recurrent disease following radical prostatectomy will occur in approximately 20% of patients, for whom the therapeutic options include surveillance, salvage radiotherapy, or hormonal therapy. This review will focus on the evidence for salvage radiotherapy. Efficacy results of 30-50% have been reported from multiple retrospective series, with minimal morbidity. Unfortunately there are no randomized or prospective studies in this area. Results of salvage radiotherapy improve when given earlier, ideally with the serum prostate-specific antigen <1 ng/mL. Other positive prognosticators are positive margins at radical prostatectomy, longer prostate-specific antigen doubling times, lower radical prostatectomy Gleason scores, and the absence of lymph node metastases. Current standard dosage is 64 Gy or slightly higher, although the optimal dosage has yet to be defined with prospective randomized trials. Salvage radiotherapy can provide a durable response when given early, and patients with recurrent disease should be considered for treatment or enrolment in clinical trials. (author)

  5. Epistemological barriers to radical behaviorism.

    Science.gov (United States)

    O'Donohue, W T; Callaghan, G M; Ruckstuhl, L E

    1998-01-01

    The historian and philosopher of science Gaston Bachelard proposed the concept of epistemological barriers to describe the intellectual challenges encountered by scientists in their work. In order to embrace novel ways of approaching a problem in science, scientists must overcome barriers or obstacles posed by their prior views. For example, Einsteinian physics presents scientists with claims that space is curved and that time and space are on the same continuum. We utilize Bachelard's concept of epistemological barriers to describe the differences between the intellectual journeys students pursuing advanced studies face when attempting to accept cognitive psychology or radical behaviorism. We contend that the folk psychological beliefs that students typically hold when entering these studies pose less challenge to cognitive psychology than to radical behaviorism. We also suggest that these barriers may also partly be involved in the problematic exegesis that has plagued radical behaviorism. In close, we offer some suggestions for dealing with these epistemological barriers. PMID:22478314

  6. Evaluation of Free Radical Scavenging Activity of Hydroethanolic Extract of Bacopa monnieri Through DPPH Assay

    Directory of Open Access Journals (Sweden)

    DISHA PANT

    2015-05-01

    Full Text Available The antioxidant potential of Bacopa monnieri in vitro through DPPH free radical scavenging assay, was evaluated using ascorbic acid as standard. There was a concentration dependent increase in percentage inhibition of DPPH free radical by ascorbic acid and hydroethanolic extract of Bacopa monnieri. The IC50 of the extract was found to be 28µg/ml and 270µg/ml for ascorbic acid and plant extract, with regression coefficients (r2 0.94 and 0.89, respectively. The hydroethanolic extract of Bacopa monnieri has a significant antioxidant potentiality comparable to a standard antioxidant like ascorbic acid.

  7. Free radical facilitated damage of ungual keratin.

    Science.gov (United States)

    Khengar, Rajeshree H; Brown, Marc B; Turner, Rob B; Traynor, Matthew J; Holt, Katherine B; Jones, Stuart A

    2010-09-01

    Thioglycolic acid (TA) and urea hydrogen peroxide (urea H(2)O(2)) are thought to disrupt alpha-keratin disulfide links in the nail. However, optimal clinical use of these agents to improve the treatment of nail disorders is currently hindered by a lack of fundamental data to support their mechanism of action. The aim of this study was to investigate how the redox environment of ungual keratin, when manipulated by TA and urea H(2)O(2), influenced the properties of the nail barrier. Potentiometric and voltammetric measurements demonstrated that urea H(2)O(2) obeyed the Nernst equation for a proton coupled one-electron transfer redox process while TA underwent a series of redox reactions that was complicated by electrode adsorption and dimer formation. The functional studies demonstrated that nail permeability, measured through TBF penetration (38.51+/-10.94 microg/cm(2)/h) and nail swelling (244.10+/-14.99% weight increase), was greatest when relatively low concentrations of the thiolate ion were present in the applied solution. Limiting the thiolate ion to low levels in the solution retards thiolate dimerisation and generates thiyl free radicals. It appeared that this free radical generation was fundamental in facilitating the redox-mediated keratin disruption of the ungual membrane. PMID:20550963

  8. The role of proteins in damage induced by free radicals

    Energy Technology Data Exchange (ETDEWEB)

    Gebicki, J.M. [Macquarie Univ., North Ryde, NSW (Australia). School of Biological Sciences

    1996-12-31

    The initial consequence of oxidative stress in living organisms is chemical modification of cell components. Recently increasing attention in this area has been paid to the modification of proteins. A form of protein modification which has been studied in some detail only recently is peroxidation. In the last 8 years, we and our collaborators have shown that a range of isolated proteins acquire hydroperoxide groups when exposed to a range of biologically plausible oxidants. These include HO free radicals generated by radiation or in the Fenton reaction, peroxyl radicals, oxidants released by activated neutrophils, and peroxynitrite. In more complex systems, we also found protein peroxides in the apo B component of LDL treated with 20 {mu}M Cu{sup ++}, and in irradiated blood serum. These observations suggest that the formation of protein peroxides is a possible consequence of oxidative stress in vivo. A remarkable feature of the process of protein peroxidation is its high efficiency. This is most easily measured with proteins oxidized by radiation-generated free radicals. It was found that, for some proteins, peroxide yields reached 40% of the numbers of HO radicals generated. Thus in effect, almost half of these radicals can be converted to the much more long-lived protein peroxide groups. If they, in turn, have the capacity to damage other molecules, the major oxidative pathway in vivo may have the sequence: free radical ? protein peroxide ? another oxidized molecule. This hypothesis was tested by studying the ability of protein peroxides to react with selected molecules and the results are briefly discussed. Clearly, these effects are specific to individual proteins. More generally, amino acid and protein peroxides were found to be a potential source of a range of free radicals when reduced by Fe{sup ++}. If this turns out to be a common phenomenon, protein peroxides may prove to be a major source of oxidative damage.

  9. Radical democratic politics and feminism

    Directory of Open Access Journals (Sweden)

    Martínez Labrin, Soledad

    2006-05-01

    Full Text Available In the article I present a reflection around the radical democratic project proposed by Chantal Mouffe and Ernesto Laclau. Specifically, I examine the application of the project in the context of the “new social movements” and especially, of feminist movement. I state the need of drawing attention to universalism and essentialism as the main obstacles to generate a collective proposal without margins. Nevertheless, doubts remind about the possibility of building up a feminism tailored by the radical democratic project, in a stage in which the political action of such a movement is characterized by categories that are closed and crystallized

  10. Free Radical Scavenging Activity of Some Nigerian Medicinal Plant Extracts

    Directory of Open Access Journals (Sweden)

    M.O. Sofidiya

    2006-01-01

    Full Text Available The present research evaluates the DPPH radical scavenging, total antioxidant activities, reducing power and total contents of phenolic compounds in methanolic leaf extracts of five Nigerian medicinal plants (Dalbergia saxatilis Hook.f. (Papilionacae, Ekebergia senegalensis A.Juss.(Meliaceae, Hymenocardia acida Tul. (Hymenocardiaceae, Icacina tricantha Oliv. (Icacinaceae and Salacia pallescens Oliv.(Celastraceae. Total phenols were analysed according to the Folin-Ciocalteu method. Each sample under assay condition, showed a dose-dependent effect both on free radical scavenging 1,1-diphenyl-2-picrylhydrazyl radical (DPPH and also on Fe3+ reducing power. The antioxidant activity of the plant extracts with the DPPH radical scavenging and reducing power method, were in the order Hymenocardia> Ekebergia> Salacia> Icacina> Dalbergia. H. acida and E. senegalensis possess very high radical scavenging activity in both assays. Potency of H. acida extract was of the same magnitude as that of reference ?-tocopherol. Total phenols in all the samples expressed as GAE (Gallic Acid Equivalent varied from 1.83 to 15.47mg g-1 of dry plant material. Total antioxidant activities correlated with total phenols (R2 = 0.6640 an indication that 66% of the antioxidant capacity of these extracts results from contribution of phenolic compounds. A linear positive relationship existed between the reducing power and total phenolics of the tested plant extracts (R2 = 0.9564.

  11. Setting the stage for electron transfer: Molecular basis of ABTS-binding to four laccases from Trametes versicolor at variable pH and protein oxidation state

    DEFF Research Database (Denmark)

    Christensen, Niels Johan; Kepp, Kasper Planeta

    2014-01-01

    Laccases are multi-copper oxidases having exquisite oxidation power, high stability, and multiple industrial applications. Although Km varies ∼1000-fold across laccases, the molecular basis of substrate binding is poorly understood. Furthermore, laccase isoenzymes vary substantially in stability...... and activity for unknown reasons, and are thus useful probes of stability-function trade-offs relevant to protein engineering. We report here the first systematic comparison of ABTS-binding to different proteins, i.e. the four isoforms of Trametes versicolor, using a combination of sequence clustering......, density functional theory calculations, homology modeling, and multiple induced-fit docking protocols at variable pH-dependent protonation states and T1-copper oxidation state. Clustering analysis provided a systematic overview of laccases across Trametes and revealed distinct isoenzyme classes (A–J) with...

  12. Effect of some naturally occurring iron ion chelators on the formation of radicals in the reaction mixtures of rat liver microsomes with ADP, Fe3+ and NADPH

    OpenAIRE

    Minakata, Katsuyuki; FUKUSHIMA, KAZUAKI; Nakamura, Masayuki; Iwahashi, Hideo

    2011-01-01

    In order to clarify the mechanism by polyphenols of protective effects against oxidative damage or by quinolinic acid of its neurotoxic and inflammatory actions, effects of polyphenols or quinolinic acid on the radical formation were examined. The ESR measurements showed that some polyphenols such as caffeic acid, catechol, gallic acid, D-(+)-catechin, L-dopa, chlorogenic acid and L-noradrenaline inhibited the formation of radicals in the reaction mixture of rat liver microsomes with ADP, Fe3...

  13. The Games Radicals Play: Special Issue on Free Radicals and Radical Ions

    Directory of Open Access Journals (Sweden)

    John C. Walton

    2015-02-01

    Full Text Available Chemistry and Physics have aptly been described as “most excellent children of Intellect and Art” [1]. Both these “children” engage with many playthings, and molecules rank as one of their first favorites, especially radicals, which are amongst the most lively and exciting. Checking out radicals dancing to the music of entropy round their potential energy ballrooms is surely both entertaining and enlightening. Radicals’ old favorite convolutions are noteworthy, but the new styles, modes and arrangements appearing on the scene are even more interesting. Some of these are ephemeral and enjoy only a brief appearance, others are retro-types reappearing in new guises, still others are genuinely new and “go viral” in the scientific world. This Special Issue of Molecules contains the observations and reflections of a select group of chemists and physicists fascinated by this spectacle. It contains an eclectic mix reflecting on new modes and advances as well as on permutations and combinations that revive mature themes. [...

  14. Molecular mechanisms induced by the effects of ionizing radiation on nucleic acids: Free radicals in 5-halogenated uracil derivatives after reaction of radiolysis products of water in low-temperature glass

    International Nuclear Information System (INIS)

    This thesis deals with the molecular mechanisms induced by the effects of ionizing radiation on the DNA. The study has been made for the main purpose of clarifying the possible role of the indirect effect, namely the attack of diffusible water radicals, in the process of radiosensitivity enhancement due to the incorporation of bromouracil instead of thymine into the DNA. The results of the experiments can be summarized by the statement that among the reactions studied in the low-temperature glasses, none revealed such a clear difference between uracil and thymine on the one hand, and the halogenated uracils on the other, that this difference could suffice to explain in terms of quality and quantity the observed in-vivo enhancement of radiosensitivity by halogenated uracils. This conclusion is in agreement with the results of radiobiological measurements on phagae and bacteria which in all cases revealed no or only very slight enhancement of the radiosensitivity in the indirect effect subsequent to bromouracil incorporation. (orig./AJ)

  15. Free-radical reactions induced by OH-radical attack on cytosine-related compounds: a study by a method combining ESR, spin trapping and HPLC.

    OpenAIRE

    Hiraoka, W; Kuwabara, M.; Sato, F.; Matsuda, A; Ueda, T.

    1990-01-01

    Free-radical reactions induced by OH-radical attack on cytosine-related compounds were investigated by a method combining ESR, spin trapping with 2-methyl-2-nitrosopropane and high-performance liquid chromatography (HPLC). Cytidine, 2'-deoxycytidine, cytidine 3'-monophosphate, cytidine 5'-monophosphate, 2'-deoxycytidine 5'-monophosphate and their derivatives, of which 5,6-protons at the base moiety were replaced by deuterons, and polycytidylic acid (poly(C] were employed as samples. OH radica...

  16. Characterization of Supersonic Radical Source.

    Czech Academy of Sciences Publication Activity Database

    Mašát, M.; Votava, Ond?ej

    Prague : MATFYZPRESS, 2008, s. 81-87. ISBN 978-80-7378-066-1. [WDS´08. Prague (CZ), 03.06.2009-06.06.2009] Institutional research plan: CEZ:AV0Z40400503 Keywords : spectroscopy * supersonic radical sources Subject RIV: CF - Physical ; Theoretical Chemistry

  17. Remembering Dutch-Moluccan radicalism

    DEFF Research Database (Denmark)

    Marselis, Randi Lorenz

    2016-01-01

    This article examines memory politics in relation to radical actions of young Dutch-Moluccans, more specifically a train hijacking in 1977 at the village of De Punt in the Netherlands. The article examines how these historical events were remembered in the drama-documentary television film, De Pu...

  18. Supporting radical front end innovation

    DEFF Research Database (Denmark)

    Aagaard, Annabeth; Gertsen, Frank

    2011-01-01

    of FEI, pharmaceutical FEI and radical innovation. Based on this understanding, empirical research through exploratory and inductive case studies is analyzed. The value added and the contribution of this article to the existing FEI literature is in the study of the theoretical fields of research in...... combination, in practice, and in the specificity of the empirical setting in which the issue is investigated....

  19. Is Radical Innovation Management Misunderstood?

    DEFF Research Database (Denmark)

    Kristiansen, Jimmi Normann; Gertsen, Frank

    2015-01-01

    This paper poses a critical view on radical innovation (RI) management research and practice. The study investigates how expected RI performance influences firms’ under- standing of their RI capability. RI performance is often based on output measures such as market shares or fiscal return. On the...

  20. Detecting Social Polarization and Radicalization

    DEFF Research Database (Denmark)

    Qureshi, Pir Abdul Rasool; Memon, Nasrullah; Wiil, Uffe Kock; Karampelas, Panagiotis

    2011-01-01

    This paper proposes a novel system to detect social polarization and to estimate the chances of violent radicalization associated with it. The required processes for such a system are indicated; it is also analyzed how existing technologies can be integrated into the proposed system to fulfill the...

  1. The Other Women: Radicalizing Feminism.

    Science.gov (United States)

    Puigvert, Lidia; Darder, Antonia; Merrill, Barbara; de los Reyes, Eileen; Stromquist, Nelly

    A recent international symposium on radicalizing feminism explored ways of developing a dialogic feminism that emphasizes working in different settings under the common goal of including women who have been invisible in the dominant feminist literature by furthering theories and practices based on the principles of dialogic feminism. The seminar…

  2. In vivo positron emission tomography studies on the novel nicotinic receptor agonist [{sup 11}C]MPA compared with [{sup 11}C]ABT-418 and (S)(-)[{sup 11}C]nicotine in Rhesus monkeys

    Energy Technology Data Exchange (ETDEWEB)

    Sihver, Wiebke E-mail: Wiebke.Sihver@pet.uu.se; Fasth, Karl-Johan; Oegren, Matthias; Lundqvist, Hans; Bergstroem, Mats; Watanabe, Yasuyoshi; Laangstroem, Bengt; Nordberg, Agneta

    1999-08-01

    The novel {sup 11}C-labeled nicotinic agonist (R,S)-1-[{sup 11}C]methyl-2(3-pyridyl)azetidine ([{sup 11}C]MPA) was evaluated as a positron emission tomography (PET) ligand for in vivo characterization of nicotinic acetylcholine receptors in the brain of Rhesus monkeys in comparison with the nicotinic ligands (S)-3-methyl-5-(1-[{sup 11}C]methyl-2-pyrrolidinyl)isoxazol ([{sup 11}C]ABT-418) and (S)(-)[{sup 11}C]nicotine. The nicotinic receptor agonist [{sup 11}C]MPA demonstrated rapid uptake into the brain to a similar extent as (S)(-) [{sup 11}C]nicotine and [{sup 11}C]ABT-418. When unlabeled (S)(-)nicotine (0.02 mg/kg) was administered 5 min before the radioactive tracers, the uptake of [{sup 11}C]MPA was decreased by 25% in the thalamus, 19% in the temporal cortex, and 11% in the cerebellum, whereas an increase was found for the uptake of (S)(-)[{sup 11}C]nicotine and [{sup 11}C]ABT-418. This finding indicates specific binding of [{sup 11}C]MPA to nicotinic receptors in the brain in a simple classical displacement study. [{sup 11}C]MPA seems to be a more promising radiotracer than (S)(-)[{sup 11}C]nicotine or [{sup 11}C]ABT-418 for PET studies to characterize nicotinic receptors in the brain.

  3. In vivo positron emission tomography studies on the novel nicotinic receptor agonist [11C]MPA compared with [11C]ABT-418 and (S)(-)[11C]nicotine in Rhesus monkeys

    International Nuclear Information System (INIS)

    The novel 11C-labeled nicotinic agonist (R,S)-1-[11C]methyl-2(3-pyridyl)azetidine ([11C]MPA) was evaluated as a positron emission tomography (PET) ligand for in vivo characterization of nicotinic acetylcholine receptors in the brain of Rhesus monkeys in comparison with the nicotinic ligands (S)-3-methyl-5-(1-[11C]methyl-2-pyrrolidinyl)isoxazol ([11C]ABT-418) and (S)(-)[11C]nicotine. The nicotinic receptor agonist [11C]MPA demonstrated rapid uptake into the brain to a similar extent as (S)(-) [11C]nicotine and [11C]ABT-418. When unlabeled (S)(-)nicotine (0.02 mg/kg) was administered 5 min before the radioactive tracers, the uptake of [11C]MPA was decreased by 25% in the thalamus, 19% in the temporal cortex, and 11% in the cerebellum, whereas an increase was found for the uptake of (S)(-)[11C]nicotine and [11C]ABT-418. This finding indicates specific binding of [11C]MPA to nicotinic receptors in the brain in a simple classical displacement study. [11C]MPA seems to be a more promising radiotracer than (S)(-)[11C]nicotine or [11C]ABT-418 for PET studies to characterize nicotinic receptors in the brain

  4. Photochemical synthesis of simple organic free radicals on simulated planetary surfaces - An ESR study

    Science.gov (United States)

    Tseng, S.-S.; Chang, S.

    1975-01-01

    Electron spin resonance (ESR) spectroscopy provided evidence for formation of hydroxyl radicals during ultraviolet photolysis (254 nm) at -170 C of H2O adsorbed on silica gel or of silica gel alone. The carboxyl radical was observed when CO or CO2 or a mixture of CO and CO2 adsorbed on silica gel at -170 C was irradiated. The ESR signals of these radicals slowly disappeared when the irradiated samples were warmed to room temperature. However, reirradiation of CO or CO2, or the mixture CO and CO2 on silica gel at room temperature then produced a new species, the carbon dioxide anion radical, which slowly decayed and was identical with that produced by direct photolysis of formic acid adsorbed on silica gel. The primary photochemical process may involve formation of hydrogen and hydroxyl radicals. Subsequent reactions of these radicals with adsorbed CO or CO2 or both yield carboxyl radicals, CO2H, the precursors of formic acid. These results confirm the formation of formic acid under simulated Martian conditions and provide a mechanistic basis for gauging the potential importance of gas-solid photochemistry for chemical evolution on other extraterrestrial bodies, on the primitive earth, and on dust grains in the interstellar medium.

  5. Reactions of Hydroxyalkyl Radicals with Cysteinyl Peptides in a NanoESI Plume

    Science.gov (United States)

    Stinson, Craig A.; Xia, Yu

    2014-07-01

    In biological systems, carbon-centered small molecule radicals are primarily formed via external radiation or internal radical reactions. These radical species can react with a variety of biomolecules, most notably nucleic acids, the consequence of which has possible links to gene mutation and cancer. Sulfur-containing peptides and proteins are reactive toward a variety of radical species and many of them behave as radical scavengers. In this study, the reactions between alkyl alcohol carbon-centered radicals (e.g., •CH2OH for methanol) and cysteinyl peptides within a nanoelectrospray ionization (nanoESI) plume were explored. The reaction system involved ultraviolet (UV) irradiation of a nanoESI plume using a low pressure mercury lamp consisting of 185 and 254 nm emission bands. The alkyl alcohol was added as solvent into the nanoESI solution and served as the precursor of hydroxyalkyl radicals upon UV irradiation. The hydroxyalkyl radicals subsequently reacted with cysteinyl peptides either containing a disulfide linkage or free thiol, which led to the formation of peptide- S-hydroxyalkyl product. This radical reaction coupled with subsequent MS/MS was shown to have analytical potential by cleaving intrachain disulfide linked peptides prior to CID to enhance sequence information. Tandem mass spectrometry via collision-induced dissociation (CID), stable isotope labeling, and accurate mass measurement were employed to verify the identities of the reaction products.

  6. Efficient scavenging of ?-carotene radical cations by antiinflammatory salicylates

    DEFF Research Database (Denmark)

    Cheng, Hong; Liang, Ran; Han, Rui-Min; Zhang, Jian-Ping; Skibsted, Leif Horsfelt

    2014-01-01

    anion of salicylic acid with 2.2 × 10 L mol s, but still of possible importance for light-exposed tissue. Surprisingly, acetylsalicylate, the aspirin anion, reacts with an intermediate rate in a reaction assigned to the anion of the mixed acetic-salicylic acid anhydride formed through base induced......The radical cation generated during photobleaching of ?-carotene is scavenged efficiently by the anion of methyl salicylate from wintergreen oil in a second-order reaction approaching the diffusion limit with k = 3.2 × 10 L mol s in 9:1 v/v chloroform-methanol at 23 °C, less efficiently by the...... rearrangements. The relative scavenging rate of the ?-carotene radical cation by the three salicylates is supported by DFT-calculations. © 2014 The Royal Society of Chemistry....

  7. Efficient scavenging of ?-carotene radical cations by antiinflammatory salicylates

    DEFF Research Database (Denmark)

    Cheng, Hong; Liang, Ran

    2014-01-01

    The radical cation generated during photobleaching of ?-carotene is scavenged efficiently by the anion of methyl salicylate from wintergreen oil in a second-order reaction approaching the diffusion limit with k = 3.2 × 10 L mol s in 9:1 v/v chloroform-methanol at 23 °C, less efficiently by the anion of salicylic acid with 2.2 × 10 L mol s, but still of possible importance for light-exposed tissue. Surprisingly, acetylsalicylate, the aspirin anion, reacts with an intermediate rate in a reaction assigned to the anion of the mixed acetic-salicylic acid anhydride formed through base induced rearrangements. The relative scavenging rate of the ?-carotene radical cation by the three salicylates is supported by DFT-calculations. © 2014 The Royal Society of Chemistry.

  8. ¿Es sostenible el constructivismo radical? / Is radical constructivism tenable?

    Scientific Electronic Library Online (English)

    Alfredo, Gaete.

    2013-03-01

    Full Text Available En este trabajo intento mostrar que el constructivismo epistemológico radical es un tesis insostenible, no tanto porque los argumentos a favor de dicha tesis sean deficientes sino porque hasta ahora existen problemas cruciales que ningún constructivista parece haber resuelto y que, sin embargo, debe [...] n ser resueltos para poder siquiera formular la tesis en cuestión. También me refiero a una consecuencia que estas consideraciones tienen en educación. Abstract in english In this work I try to show that radical, epistemological constructivism is an untenable thesis. Not so much because the arguments in favor of such a thesis are deficient, but because there are crucial problems that no constructivist seems to have solved and that must be solved in order for it to be [...] possible to even formulate the thesis in question. I also mention a consequence that these considerations have in education.

  9. Polyenyl cations and radical cations – synthesis, spectroscopic properties and reactions

    OpenAIRE

    Kildahl-Andersen, Geir

    2007-01-01

    In the present work, polyene precursors for the formation of charged polyenyl species were synthesised. Their conversion to charge delocalised radical cations and diamagnetic mono- and dications was carried out by treatment with Brønsted and Lewis acids. Reaction conditions were optimised to achieve sufficient stability of the charged polyenes for characterisation by modern spectroscopic methods; in particular nearinfrared absorption spectroscopy (NIR), two-dimensional nuclear magnetic resona...

  10. Arene-thioether mixed complex radical cations

    International Nuclear Information System (INIS)

    Studies of radiolytically generated radical cations in aromatic hydrocarbon solvents have led to the first direct characterization of monomeric thioether radical cations in liquid solution. Observation of these very reactive chemical intermediates is made possible by the great sensitivity of fluorescence-detected magnetic resonance (FDMR) and by solvent stabilization of the thioether radical cations via electron donation. Monomeric thioether radical cations in arene solvents such as toluene exist as arene-thioether mixed complex radical cations -- the first ?-lone pair mixed complex radical cations ever observed. Such orbital interactions are of fundamental importance for open-shell intermediates as they have consequences for both electronic structure and reactivity. Thioether radical cations provide a valuable test system to probe the chemical influence of orbital interactions that are generic to all ?-type and heteroatom-containing organic radical cations, and magnetic resonance provides unsurpassed structural resolution for condensed-phase paramagnetic intermediates

  11. Muonium radicals in benzene-styrene mixtures

    International Nuclear Information System (INIS)

    Muonium radicals were observed through their ?+SR precession frequencies in high transverse magnetic fields in pure benzene, pure styrene and their mixtures, all as liquids at room temperature. In benzene-styrene mixtures, the radicals obtained in each pure liquid are both present, so no slow (10-9-10-5 s) intermolecular exchange occurs; but strong selectivity was found with the formation of the radical from styrene being about eight-times more probable than the radical from benzene. (Auth.)

  12. The Radical Axis: A Motion Study

    Science.gov (United States)

    McGivney, Ray; McKim, Jim

    2006-01-01

    Interesting problems sometimes have surprising sources. In this paper we take an innocent looking problem from a calculus book and rediscover the radical axis of classical geometry. For intersecting circles the radical axis is the line through the two points of intersection. For nonintersecting, nonconcentric circles, the radical axis still…

  13. Radical carbonylations using a continuous microflow system

    Directory of Open Access Journals (Sweden)

    Takahide Fukuyama

    2009-07-01

    Full Text Available Radical-based carbonylation reactions of alkyl halides were conducted in a microflow reactor under pressurized carbon monoxide gas. Good to excellent yields of carbonylated products were obtained via radical formylation, carbonylative cyclization and three-component coupling reactions, using tributyltin hydride or TTMSS as a radical mediator.

  14. Free-radical chemistry of sulfite.

    OpenAIRE

    Neta, P; Huie, R E

    1985-01-01

    The free-radical chemistry of sulfite oxidation is reviewed. Chemical transformations of organic and biological molecules induced by sulfite oxidation are summarized. The kinetics of the free-radical oxidations of sulfite are discussed, as are the kinetics of the reactions of the sulfite-derived radicals SO3 and the peroxy derivative SO5 with organic compounds.

  15. Characterization of pH-Responsive Hydrogels of Poly(Itaconic acid-g-Ethylene Glycol) Prepared by UV-Initiated Free Radical Polymerization as Biomaterials for Oral Delivery of Bioactive Agents

    OpenAIRE

    Betancourt, Tania; Pardo, Juan; Soo, Ken; Peppas, Nicholas A.

    2010-01-01

    Effective oral delivery of proteins is impeded by steep pH gradients and proteolytic enzymes in the gastrointestinal tract, as well as low absorption of the proteins into the bloodstream due to their size, charge or solubility. In the present work, pH-responsive complexation hydrogels of poly(itaconic acid) with poly(ethylene glycol) grafts were synthesized for applications in oral drug delivery. These hydrogels were expected to be in collapsed configuration at low pH due to hydrogen bonding ...

  16. ESTIMATION OF HYDROXYL AND HYDROPEROXYL RADICALS CONCENTRATIONS IN THE URBAN ATMOSPHERE OF SANTIAGO

    Scientific Electronic Library Online (English)

    M. Angélica, Rubio; Eduardo, Liss; Guillermo, Villena; Victoria, Caroca; Ernesto, Gramsch; Álvaro, Ruiz.

    2005-06-01

    Full Text Available Photochemical smog episodes are frequent in Santiago of Chile city. We have measured the concentration of the main free radical precursors (formaldehyde, ozone, nitrogen dioxide, peroxyacetyl nitrate and nitrous acid), nitrogen monoxide and the irradiance. Calculations of the rate of OH* production [...] were performed for different periods of the year and at emission (Cerrillos and Estacion Central) and receptor sites (Las Condes). From these data and simple steady state considerations were derived the concentrations of hydroxyl and hydroperoxyl radicals. Daily profiles of both radicals show a noticeable accumulation during early afternoon, the time of most intense oxidants accumulation. During summer time, hydroperoxyl radical concentrations are higher in Las Condes than in Cerrillos. The concentrations calculated for both radicals are higher than those estimated in other cities, suggesting a particularly high photochemical activity in the urban atmosphere of Santiago of Chile

  17. ESTIMATION OF HYDROXYL AND HYDROPEROXYL RADICALS CONCENTRATIONS IN THE URBAN ATMOSPHERE OF SANTIAGO

    Directory of Open Access Journals (Sweden)

    M. Angélica Rubio

    2005-06-01

    Full Text Available Photochemical smog episodes are frequent in Santiago of Chile city. We have measured the concentration of the main free radical precursors (formaldehyde, ozone, nitrogen dioxide, peroxyacetyl nitrate and nitrous acid, nitrogen monoxide and the irradiance. Calculations of the rate of OH* production were performed for different periods of the year and at emission (Cerrillos and Estacion Central and receptor sites (Las Condes. From these data and simple steady state considerations were derived the concentrations of hydroxyl and hydroperoxyl radicals. Daily profiles of both radicals show a noticeable accumulation during early afternoon, the time of most intense oxidants accumulation. During summer time, hydroperoxyl radical concentrations are higher in Las Condes than in Cerrillos. The concentrations calculated for both radicals are higher than those estimated in other cities, suggesting a particularly high photochemical activity in the urban atmosphere of Santiago of Chile

  18. [Erectile rehabilitation after radical prostatectomy].

    Science.gov (United States)

    Droupy, S; Giuliano, F; Costa, P

    2009-12-01

    The concept of penile rehabilitation involves the procedures designed to improve oxygen delivery the penile erectile tissue to minimized tissue damage during the period of neural recovery following radical prostatectomy. Many basic research studies support the rationale and mechanism of the concept of penile rehabilitation, however they are few clinical studies in the literature that provide a clear medical evidence of its efficacy in patients. Waiting for new data, it is recommended to propose to the patients, following a radical prostatectomy, an active pharmacological penile rehabilitation. This rehabilitation involves counselling with the couple to have regular sexual activities, ideally 1 to 3 times a week. Penile erections could be induced by intracavernosal injections of PGE1 or improved by using PDE5 inhibitors on demand. The results of daily use of PDE5 inhibitor are conflicting and then it cannot be recommended systematically waiting for new data. The rehabilitation could be maintained for about 2 years as results improve with time. PMID:20123519

  19. Antioxidant Effects of Herbal Tea Leaves from Yacon (Smallanthus sonchifolius) on Multiple Free Radical and Reducing Power Assays, Especially on Different Superoxide Anion Radical Generation Systems.

    Science.gov (United States)

    Sugahara, Shintaro; Ueda, Yuto; Fukuhara, Kumiko; Kamamuta, Yuki; Matsuda, Yasushi; Murata, Tatsuro; Kuroda, Yasuhiro; Kabata, Kiyotaka; Ono, Masateru; Igoshi, Keiji; Yasuda, Shin

    2015-11-01

    Yacon (Smallanthus sonchifolius), a native Andean plant, has been cultivated as a crop and locally used as a traditional folk medicine for the people suffering from diabetes and digestive/renal disorders. However, the medicinal properties of this plant and its processed foods have not been completely established. This study investigates the potent antioxidative effects of herbal tea leaves from yacon in different free radical models and a ferric reducing model. A hot-water extract exhibited the highest yield of total polyphenol and scavenging effect on 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical among four extracts prepared with hot water, methanol, ethanol, and ethylacetate. In addition, a higher reducing power of the hot-water extract was similarly demonstrated among these extracts. Varying concentrations of the hot-water extract resulted in different scavenging activities in four synthetic free radical models: DPPH radical (EC50 28.1 ?g/mL), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) cation radical (EC50 23.7 ?g/mL), galvinoxyl radical (EC50 3.06 ?g/mL), and chlorpromazine cation radical (EC50 475 ?g/mL). The yacon tea-leaf extract further demonstrated superoxide anion (O2 (-) ) radical scavenging effects in the phenazine methosulfate-NADH-nitroblue tetrazolium (EC50 64.5 ?g/mL) and xanthine oxidase assay systems (EC50 20.7 ?g/mL). Subsequently, incubating human neutrophilic cells in the presence of the tea-leaf extract could suppress the cellular O2 (-) radical generation (IC50 65.7 ?g/mL) in a phorbol 12-myristate 13-acetate-activated cell model. These results support yacon tea leaves may be a good source of natural antioxidants for preventing O2 (-) radical-mediated disorders. PMID:26457985

  20. Remembering Dutch-Moluccan radicalism

    DEFF Research Database (Denmark)

    Marselis, Randi

    1800-01-01

    This article examines memory politics in relation to radical actions of young Dutch-Moluccans, more specifically a train hijacking in 1977 at the village of De Punt in the Netherlands. The article examines how these historical events were remembered in the drama-documentary television film, De Punt (Smitsman, 2009), as well as in user-generated comments in an online discussion. The television film proposed an inclusive memory discourse that acknowledged the difficult memories of all involved par...

  1. Penile rehabilitation after radical prostatectomy

    DEFF Research Database (Denmark)

    Fode, Mikkel; Ohl, Dana A; Ralph, David; Sønksen, Jens

    2013-01-01

    The pathophysiology of erectile dysfunction after radical prostatectomy (RP) is believed to include neuropraxia, which leads to temporarily reduced oxygenation and subsequent structural changes in penile tissue. This results in veno-occlusive dysfunction, therefore, penile rehabilitation programmes focus on tissue oxygenation. Animal studies support the use of phosphodiesterase type 5 inhibitors (PDE5Is) after cavernous nerve damage but results from human studies are contradictory. The largest s...

  2. Urogynaecological dysfunction after radical hysterectomy

    DEFF Research Database (Denmark)

    Axelsen, S M; Petersen, L K; Axelsen, Susanne Maigaard

    2006-01-01

    AIMS: To identify self-reported urogynaecological dysfunctions in women treated by radical hysterectomy, and predict risk factors. METHODS: A survey using questionnaires. Questionnaires were mailed to 396 patients. RESULTS: Symptoms of urinary incontinence and urinary retention were reported by more than one-third, respectively. One-third of the patients reported cystitis and dysuria. However, 78% of the women did not consider their symptoms as a problem. Analyses identified body mass index, at ...

  3. Free radical mediated cellulose degradation

    OpenAIRE

    Johansson, Erik

    2003-01-01

    This thesis addresses the mechanisms involved in cellulosedegradation in general and Totally Chlorine Free (TCF) bleachingof pulp in particular. The thesis shows that the cellulosedegradation during high consistency ozone bleaching is explainedby free radical chain reactions. By simulation, it has been shown that the number, weight andviscosity average of liner polymer chain length can be used tocalculate the number of random scissions in a linear polymer ofany molecular weight distribution, ...

  4. Kierkegaard as radical Christian thinker

    OpenAIRE

    Mojsi? Sofija

    2013-01-01

    The main goal of this paper is the reaffirmation and emphasis of the radical, revolutionary aspect of Kierkegaard’s thought which has been mainly neglected in the standard literature on the Danish thinker. The author contends that there were two crises in Kierkegaard’s life: in 1838 and 1848. In 1838 Kierkegaard completely withdrew from the world and people into his “hidden inwardness”, which he claimed to be the essence of true Christianity. In 1848 he bro...

  5. Evidence for formation of hydroxyl radicals during reperfusion after global cerebral ischaemia in rats using salicylate trapping and microdialysis

    DEFF Research Database (Denmark)

    Christensen, Thomas; Bruhn, T; Balchen, T; Diemer, Nils Henrik

    1994-01-01

    Systemic administration of salicylate (SA) to rats (100 mg kg-1 i.p. ) was used as an in vivo trap of hydroxyl radicals (.OH). In the brain SA reacts with hydroxyl radicals to form the stable adducts 2, 3- and 2,5 dihydroxybenzoic acid (DHBAs) which can thus be taken as an index of .OH formation...

  6. Cyclic Group 15 Radical Cations.

    Science.gov (United States)

    Brückner, Angelika; Hinz, Alexander; Priebe, Jacqueline B; Schulz, Axel; Villinger, Alexander

    2015-06-15

    Singlet cyclo-1,3-dipnicta-2,4-diazane-1,3-diyls of the type [E(?-NTer)2 E] (2, E=P, As, Ter=2,6-dimesitylphenyl) can undergo a one-electron-oxidation utilizing silver salts of weakly coordinating anions such as [AgLn][B(C6F5)4 ] (L=donor solvents) to afford the novel cyclic radical cations, [E(?-NTer)2E](+·) (3(+·)). When smaller and more basic anions were employed in the reaction, the anions were found to form covalent bonds to the radical centers yielding dipnictadiazanes, [FP(?-NTer)2PF] (5) and [(CF3CO2)P(?-NTer)2P(CF3CO2)] (6). A two-electron oxidation process, resulting in the formation of dications of the type [E(?-NTer)2E](2+), could not be observed. Computational and EPR data revealed that the spin density is almost completely localized at the two heavier pnictogen centers E of the former 1,3-dipnictadiazane-1,3-diyls. The bonding situation in the radical cations features a rare example of a transannular one-electron ? bond without having a ? bond. PMID:25960190

  7. Penile rehabilitation after radical prostatectomy.

    Science.gov (United States)

    Cohen, David Jacques; Glina, Sidney

    2015-01-01

    Erectile dysfunction (ED) is the main and most frequent side effect after radical prostatectomy. Also, ED is the primary impact factor for quality of life after radical prostatectomy. ED post radical prostatectomy is mainly due to lesions in the neurovascular bundles which can occur by partial or total sectioning, by stretching (the most common), or by thermal lesion of the nervous fibers, leading to a condition called "neuropraxia". The term penile rehabilitation (PR) after prostatectomy has been defined as any intervention with the intent of reestablishing preoperative erectile function and includes the isolated or combined use of phosphodiesterase 5 inhibitors (PDE5i), intracavernous injection, vacuum erectile device therapy, and use of intraurethral drugs. The use of intracavernous drugs, of intraurethral prostaglandin and the use of vacuum therapy have a poorly defined role regarding postoperative penile rehabilitation and must be better investigated through further studies. The use of PDE5i as PR is strongly supported by experimental research, but most clinical trials found controversial results. PMID:25642716

  8. Quantum Mechanical Calculations of Cytosine, Thiocytosine and Their Radical Ions

    Science.gov (United States)

    Singh, Rashmi

    2010-08-01

    The RNA and DNA are polymer that share some interesting similarities, for instance it is well known that cytosine is the one of the common nucleic acid base. The sulfur is characterized as a very reactive element and it has been used, in chemical warfare agents. Since the genetic information is based on the sequence of the nucleic acid bases. The quantum mechanical calculations of the energies, geometries, charges and vibrational characteristics of the cytosine and thiocytosine. and their corresponding radicals were carried out by using DFT method with b3lyp/6-311++g** basis set.

  9. Organic peroxy free radicals as ultimate agents in oxygen toxicity

    International Nuclear Information System (INIS)

    The role of organic peroxy free radicals in the interaction of oxygen with important biomolecules in in vitro radiation damage studies is reviewed. These studies include the reaction of RO2. but not R. or 02-. with NADH, antioxidants, unsaturated fatty acids, anti-inflammatory drugs and amino acids; the effects of 02-. and CCl302. on the survival of bacterio-phage T2 in the absence and presence of several anti-inflammatory drugs; the inactivation of lyzozyme by CCl302-.; the inactivation of alcohol dehydrogenase by RO2. generally but not 02.; and the protection of ADH by antioxidants and superoxide dismutase. (U.K.)

  10. Electron spin resonance studies on reduction process of nitroxyl spin radicals used in molecular imaging

    International Nuclear Information System (INIS)

    The Electron spin resonance studies on the reduction process of nitroxyl spin probes were carried out for 1mM 14N labeled nitroxyl radicals in pure water and 1 mM concentration of ascorbic acid as a function of time. The electron spin resonance parameters such as signal intensity ratio, line width, g-value, hyperfine coupling constant and rotational correlation time were determined. The half life time was estimated for 1mM 14N labeled nitroxyl radicals in 1 mM concentration of ascorbic acid. The ESR study reveals that the TEMPONE has narrowest line width and fast tumbling motion compared with TEMPO and TEMPOL. From the results, TEMPONE has long half life time and high stability compared with TEMPO and TEMPOL radical. Therefore, this study reveals that the TEMPONE radical can act as a good redox sensitive spin probe for molecular imaging

  11. A time-resolved Raman study of the reaction of OH radicals with p-phenylenediamine

    International Nuclear Information System (INIS)

    In a previous study of the reaction of OH with aromatic diamines the absorption spectrum attributed to the OH adducts was reported to be virtually identical with that of the radical cations, differing only in intensity. Here we apply pulse radiolysis methods with time-resolved resonance Raman detection to examine the intermediates formed in the OH oxidation of p-phenylenediamine. These studies show that in neutral and basic solution the OH adducts, if formed, have a very short lifetime, that the absorption spectrum previously assigned to the OH adduct is, in fact, that of the radical cation, and that this radical cations does not protonate in moderately acidic solutions

  12. Screening of various botanical extracts for antioxidant activity using DPPH free radical method.

    Science.gov (United States)

    Waqas, Muhammad Khurram; Saqib, Najam-Us; Rashid, Saeed-Ur; Shah, Pervaiz Akhtar; Akhtar, Naveed; Murtaza, Ghulam

    2013-01-01

    Aiming at the exploration of herbal use by society, crude extracts of the seeds of some commonly used medicinal plants (Vitis vinifera, Tamarindus indica and Glycin max) were screened for their free radical scavenging properties using ascorbic acid as standard antioxidant. Free radical scavenging activity was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical. The overall antioxidant activity of grape seeds (Vitis vinifera) was the strongest, followed in descending order by soybean (Glycin max) and tamarind (Tamarindus indica). The seeds extract of Vitis vinifera, Glycin max and Tamarindus indica showed 85.61%, 83.45% and 79.26%, DPPH scavenging activity respectively. PMID:24311867

  13. Novel azo-peresters radical initiators used for the synthesis of acrylic pressure-sensitive adhesives

    Directory of Open Access Journals (Sweden)

    2008-04-01

    Full Text Available Acrylic pressure-sensitive adhesives (PSA based on two monomers: 2-ethylhexyl acrylate and acrylic acid were synthesized in organic solvent ethyl acetate using AIBN (2, 2'?-azo-diisobutyronitrile and new synthesized azo-peresters as radical initiators. After polymerization the viscosity, molecular weight and polydispersity of synthesized acrylic PSA were evaluated. The novel synthesized radical azo-perester initiators were synthesized, isolated and compared with industrial predominant usable azo-initiator AIBN.

  14. Pulsed radiation studies of carotenoid radicals and excited states

    International Nuclear Information System (INIS)

    The one-electron reduction potentials of the radical cations of five dietary carotenoids, in aqueous micellar environments, have been obtained from a pulse radiolysis study of electron transfer between the carotenoids and tryptophan radical cations as a function of pH, and lie in the range 980 to 1060 mV. The decays of the carotenoid radical cations suggest a distribution of exponential lifetimes. The radicals persist for up to about one second, depending on the medium and may re-orientate within a biological environment to react with other biomolecules, such as tyrosine, cysteine or ascorbic acid, which was indeed confirmed. Spectral information of carotenoid pigmented liposomes has been collected, subsequently pulse radiolysis was used to generate the radical cations of ?-carotene, zeaxanthin and lutein, in unilamellar vesicles of dipalmitoyl phosphatidyl choline. The rate constants for the 'repair' of these carotenoid radical cations by water-soluble vitamin C were found to be similar (?1 x 107 M-1s-1) for ?-carotene and zeaxanthin and somewhat lower (?0.5 x 107 M-1s-1) for lutein. The results are discussed in terms of the microenvironment of the carotenoids and suggest that for ?-carotene, a hydrocarbon carotenoid, the radical cation is able to interact with a water-soluble species even though the parent hydrocarbon carotenoid is probably entirely in the non-polar region of the liposome. Studies investigating the ability of ingested lycopene to protect human lymphoid cells against singlet oxygen and nitrogen dioxide radical mediated cell damage have shown that a high lycopene diet is beneficial in protecting human cells against reactive oxygen species. Triplet states of carotenoids were produced in benzene solvent and their triplet lifetimes were found to depend on the concentration of the parent molecule. The rate constants obtained for ground state quenching correlate with the number of conjugated double bonds, the longer chain systems having higher quenching rate constants. The efficiency of deactivation of singlet oxygen by three asymmetric carotenoids was measured via time-resolved luminescence detection. In benzene, the deactivation efficiency was found to fit the trend reported previously, in that quenching efficiency increases with increasing wavelength of ??* absorption of the maxima of carotenoids. Both hydroxyl and carbonyl groups were shown to lower the quenching ability. The singlet oxygen deactivation efficiency of carotenoids incorporated within the bilayer of dipalmitoyl phosphotidyl choline liposomes and water/alcohol mixtures was determined concluding that out of the two xanthophylls and one carotene investigated, ?-carotene was the most efficient at singlet oxygen deactivation. The results are discussed in terms of the microenvironment of the carotenoids. (author)

  15. Bactericidal activity of alkyl peroxyl radicals generated by heme-iron-catalyzed decomposition of organic peroxides.

    Science.gov (United States)

    Akaike, T; Sato, K; Ijiri, S; Miyamoto, Y; Kohno, M; Ando, M; Maeda, H

    1992-04-01

    To clarify the nature of cytocidal molecular species among the radicals generated in the iron-catalyzed reactions of peroxides (ROOH), we examined the cytocidal effects of these radicals against gram-positive and gram-negative bacteria in the presence or absence of various radical scavengers. Three organic peroxides, t-butyl hydroperoxide (t-BuOOH), methyl ethyl ketone peroxide (MEKOOH), and cumene hydroperoxide, were used. Each radical generated from these peroxides was identified and quantitated by electron spin resonance (ESR) spin trapping with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). The major cytotoxic radical species generated in the mixtures of various peroxides and heme iron, especially methemoglobin, metmyoglobin, or hemin, was the alkyl peroxyl radical (ROO.). Strong bactericidal action against gram-positive bacteria was observed in the peroxide-heme iron system, especially in the case of t-BuOOH and MEKOOH. Killing curves for gram-positive bacteria showed an initial lag period, which may indicate the multihit/multitarget kinetics of cell killing. When the diethylenetriamine pentaacetic acid (DTPA)-Fe2+ complex was used as a catalyst for decomposition of various peroxides, alkyl, alkoxyl, and alkyl peroxyl radicals were identified by spin-trapping analysis. However, study of the time course of alkyl peroxyl radical production in the DTPA-Fe2+ complex system revealed that radical species generated in this system were very short lived: a maximal level was achieved within 1 min and then declined sharply, and no bactericidal activity was observed after 10 min. In contrast, the alkyl peroxyl radical level generated by the organic peroxide-heme iron system remained high for 30 min or longer. The generation of alkyl peroxyl radicals quantified by ESR correlated quite well with the bactericidal effect of the system of peroxide plus iron. In addition, bactericidal activity was completely inhibited by the addition of the spin trap DMPO, as well as of other various radical scavengers (alpha-tocopherol and L-ascorbic acid), into the peroxide-heme iron system, but this effect was not observed with superoxide dismutase, beta-carotene, dimethyl sulfoxide, diphenylamine, or butylated hydroxyltoluene. In view of these results, it is assumed that alkyl peroxyl radicals are the potent molecular species that are cytotoxic against bacteria, whereas alkoxyl radicals (RO.) generated in this system do not affect bacterial viability. PMID:1312811

  16. Sonovoltammetric behavior of ascorbic acid and dehydroascorbic acid at glassy carbon electrodes: Analysis using pulsed sonovoltammetry

    OpenAIRE

    Richard G. Compton; Matysik, Frank-Michael

    1996-01-01

    The effect of power ultrasound on the voltammetric behavior of ascorbic acid and dehydroascorbic acid at a glassy carbon electrode is described. The voltammetric characteristics of both compounds were found to be modified by ultrasonically formed radicals. In the case of dehydroascorbic acid the single sweep voltammogram shows an anodic signal in the presence of ultrasound which probably results from the formation of an oxidizable radical known to be an intermediate of ascorbic acid oxidation...

  17. On the reaction of molecular oxygen with thiyl radicals: a re-examination

    International Nuclear Information System (INIS)

    Absolute rate constants for the addition of oxygen to thiyl radicals, i.e. RS radicals + O2 ? RSOO radicals, have been determined by applying a new competition method based on RS radicals formation via one-electron reduction of the corresponding disulphides, and the competition between RS radicals reacting with O2 and an electron donor such as ascorbate. Bimolecular rate constants have been obtained for the thiyl radicals derived from cysteine (6.1 x 107 mol-1 dm3 s-1), penicillamine (2.5 x 107 mol-1 dm3 s-1), homocysteine (8.0 x 107 mol-1 dm3 s-1), cysteamine (2.8 x 107 mol-1 dm3 s-1), 3-thiopropionic acid (2.2 x 108 mol-1 dm3 s-1) and glutathione (3.0 x 107 mol-1 dm3 s-1), respectively. The values obtained for the O2 addition to the thiyl radicals from glutathione and cysteine are considerably lower (by about two orders of magnitude) than those previously published. This indicates that the RS radicals + O2 reaction may be of complex nature and is generally a process which is not solely controlled by the diffusion of the reactants. (author)

  18. Radical Budget and Ozone Production in Houston, TX during SHARP 2009

    Science.gov (United States)

    Ren, X.; van Duin, D.; Cazorla, M.; Chen, S.; Brune, W. H.; Flynn, J. H.; Lefer, B. L.; Dibb, J. E.; Wong, K.; Tsai, C.; Stutz, J.

    2010-12-01

    The chemistry of atmospheric radicals, especially the hydroxyl radical (OH) and hydroperoxyl radical (HO2), together called HOx, is deeply involved in the formation of the secondary pollutants ozone and fine particles. Radical precursors such as nitrous acid (HONO) and formaldehyde (HCHO) significantly affects HOx budget in urban environments like Houston. These chemical processes connect surface emissions, both human and natural, to local and regional pollution, and climate change. Using the data collected during the Study of Houston Atmospheric Radical Precursors (SHARP) in Houston, TX in spring 2009, we test our understanding of photochemistry through the analysis of the radical budget and ozone production. A numerical box model was used to simulate the oxidation processes and observed OH and HO2 during this study. Using the model results, we calculate the radical budget and analyze the sensitivity of ozone production to nitrogen oxides (NOx) and volatile organic compounds (VOCs). The radical budget shows that the photolysis of HONO and the photolysis of HCHO were significant HOx sources in this urban environment. We also compare the observed OH reactivity and ozone production rate to the model calculations. In general, ozone production rate was VOC limited in the morning and NOx limited in the afternoon. This relationship results from the ratio of VOCs to NOx in Houston. Results from this study provide additional support for regulatory actions to reduce reactive VOCs in Houston in order to reduce ozone and other secondary pollutants.

  19. A Radical Cascade Classifier for Handwritten Chinese Character Recognition

    OpenAIRE

    Enzhi Ni; Changle Zhou; Minjun Jiang

    2012-01-01

    Radical extraction is the core technique for radical-based Chinese character recognition. In this paper, we proposed a new method of radical extraction – radical cascade classifier. The radical cascade classifier consists of multiple AdaBoost classifiers. It can detect and extract specific radical from characters. To apply cascade classifier to radical extraction, we focus on two main points: feature selection and radical detection. In this paper, we discussed feature selection for the ...

  20. Effect of electron-withdrawing power of the substituted group on ${}^{\\bullet}$OH radical reaction with substituted aryl sulphides: A pulse radiolysis study

    Indian Academy of Sciences (India)

    Hari Mohan

    2002-12-01

    In neutral aqueous solution of (phenylthio)acetic acid, hydroxyl radical is observed to react with a bimolecular rate constant of 7.2 × 109 dm3 mol-1 s-1 and the transient absorption bands are assigned to ${}^{\\bullet}$OH radical addition to benzene and sulphur with a rough estimated values of 50 and 40% respectively. The reaction of the ${}^{\\bullet}$OH radical with diphenyl sulphide ( = 4.3 × 108 dm3 mol-1 s-1) is observed to take place with formation of solute radical cation, OH-adduct at sulphur and benzene with estimated values of about 12, 28 and 60% respectively. The transient absorption bands observed on reaction of ${}^{\\bullet}$OH radical, in neutral aqueous solution of 4-(methylthio) phenyl acetic acid, are assigned to solute radical cation (max = 550 and 730 nm), OH-adduct at sulphur (max = 360 nm) and addition at benzene ring (max = 320 nm). The fraction of ${}^{\\bullet}$OH radical reacting to form solute radical cation is observed to depend on the electron-withdrawing power of substituted group. In acidic solutions, depending on the concentration of acid and electron-withdrawing power, solute radical cation is the only transient species formed on reaction of ${}^{\\bullet}$OH radical with the sulphides studied.

  1. Establishment of activity indicator of TiO2 photocatalytic reaction-Hydroxyl radical trapping method

    International Nuclear Information System (INIS)

    In this study, a new, low cost and easy method, hydroxyl radical trapping method, was employed to investigate the photo-activity of UV/TiO2 photocatalytic reaction. The Taguchi method was utilized to optimize the preparation of titanium dioxide (TiO2) thin-film reactor through the modified chemical vapor deposition (CVD) method. The optimal yield of hydroxyl radicals was then evaluated by calculating the conversion ratio of salicylic acid under the optimal conditions. In the experiments, salicylic acid was used as the free-radical scavenger and the formation of three different intermediates were examined to shed light on the trend and kinetics of reaction of hydroxyl radical with organic substance under different operation conditions. The results indicated that the yield of hydroxyl radicals increased with increasing irradiation intensity and dissolved oxygen level. The optimal experimental conditions obtained in this study were irradiation with intensity of 2.9 mW cm-2 on salicylic acid at concentration of 250 mg L-1 by both agitation and aeration processes (dissolved oxygen level = 8.2 mg O2 L-1) at pH 5. Such conditions could achieve the optimal hydroxyl radical yield of 5.1 x 10-17 M.

  2. Laser spectroscopy of hydrocarbon radicals

    Energy Technology Data Exchange (ETDEWEB)

    Chen, P. [Harvard Univ., Cambridge, MA (United States)

    1993-12-01

    The author reports the application of supersonic jet flash pyrolysis to the specific preparation of a range of organic radicals, biradicals, and carbenes in a skimmed molecular beam. Each species was produced cleanly and specifically, with little or no secondary reactions by the thermal dissociation of appropriately designed and synthesized organic precursors. Photoelectron spectra of the three isomeric C{sub 3}H{sub 2} carbenes, ortho-benzyne, and the {alpha},3-dehydrotoluene biradical, were used to establish adiabatic ionization potentials for use in thermochemical determinations.

  3. Aromatic-radical oxidation chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Glassman, I.; Brezinsky, K. [Princeton Univ., NJ (United States)

    1993-12-01

    The research effort has focussed on discovering an explanation for the anomalously high CO{sub 2} concentrations observed early in the reaction sequence of the oxidation of cyclopentadiene. To explain this observation, a number of plausible mechanisms have been developed which now await experimental verification. One experimental technique for verifying mechanisms is to probe the reacting system by perturbing the radical concentrations. Two forms of chemical perturbation of the oxidation of cyclopentadiene were begun during this past year--the addition of NO{sub 2} and CO to the reacting mixture.

  4. Generation of OH radicals at palladium oxide nanoparticle modified electrodes, and scavenging by fluorescent probes and antioxidants.

    OpenAIRE

    Liu, J.; Lagger, G; Tacchini, P; GIRAULT, H. H.

    2008-01-01

    The reduction of palladium oxide nanoparticles in the presence of hydrogen peroxide or dissolved oxygen gives rise to a catalytic reduction current dependent on the hydrogen peroxide concentration or the oxygen concentration. Using terephthalic acid as an OH radical scavenger yielding the fluorescent 2-hydroxyterephthalic acid, we demonstrate that the catalytic current stems from the freshly exposed palladium metal re-oxidation by OH radicals. A kinetic model is presented to account for thes...

  5. Free radical kinetics of irradiated durum wheat

    International Nuclear Information System (INIS)

    In the present work, a detailed ESR investigation of characteristic features and kinetic behaviors at three different temperatures of free radicals produced in a species of durum wheat cultivated in Turkey and irradiated at doses of up to 5 kGy by a ? source, is reported. Unirradiated wheat samples exhibit a weak, single-line ESR signal originating from a radical of unknown structure called radical III in this work. Irradiation produces two more radicals identified as hydroxyalkyl (I) and aldehydalkyl (II) radicals beside radical III. The radicals (I, II and III) follow complicated kinetics. Species I and II initially decay very fast after the irradiation followed by slower decay. Radical half-life times depend on whether they were induced in the crystalline or amorphous fractions of the wheat starch. Activation energy values of the radicals were found to follow the order Ea(III)>Ea(II)>Ea(I). ESR parameters of the radical species were determined by simulating experimental spectra recorded following the irradiation. Room temperature dose-response curves and variations of different spectral parameters between 120 and 390 K were also studied

  6. Free radical kinetics of irradiated durum wheat

    Science.gov (United States)

    Korkmaz, M.; Polat, M.

    2000-04-01

    In the present work, a detailed ESR investigation of characteristic features and kinetic behaviors at three different temperatures of free radicals produced in a species of durum wheat cultivated in Turkey and irradiated at doses of up to 5 kGy by a ? source, is reported. Unirradiated wheat samples exhibit a weak, single-line ESR signal originating from a radical of unknown structure called radical III in this work. Irradiation produces two more radicals identified as hydroxyalkyl (I) and aldehydalkyl (II) radicals beside radical III. The radicals (I, II and III) follow complicated kinetics. Species I and II initially decay very fast after the irradiation followed by slower decay. Radical half-life times depend on whether they were induced in the crystalline or amorphous fractions of the wheat starch. Activation energy values of the radicals were found to follow the order Ea(III)> Ea(II)> Ea(I). ESR parameters of the radical species were determined by simulating experimental spectra recorded following the irradiation. Room temperature dose-response curves and variations of different spectral parameters between 120 and 390 K were also studied.

  7. Free radical kinetics of irradiated durum wheat

    Energy Technology Data Exchange (ETDEWEB)

    Korkmaz, M.; Polat, M

    2000-04-01

    In the present work, a detailed ESR investigation of characteristic features and kinetic behaviors at three different temperatures of free radicals produced in a species of durum wheat cultivated in Turkey and irradiated at doses of up to 5 kGy by a {gamma} source, is reported. Unirradiated wheat samples exhibit a weak, single-line ESR signal originating from a radical of unknown structure called radical III in this work. Irradiation produces two more radicals identified as hydroxyalkyl (I) and aldehydalkyl (II) radicals beside radical III. The radicals (I, II and III) follow complicated kinetics. Species I and II initially decay very fast after the irradiation followed by slower decay. Radical half-life times depend on whether they were induced in the crystalline or amorphous fractions of the wheat starch. Activation energy values of the radicals were found to follow the order E{sub a}(III)>E{sub a}(II)>E{sub a}(I). ESR parameters of the radical species were determined by simulating experimental spectra recorded following the irradiation. Room temperature dose-response curves and variations of different spectral parameters between 120 and 390 K were also studied.

  8. Nanostructured hybrid hydrogels prepared by a combination of atom transfer radical polymerization and free radical polymerization

    Science.gov (United States)

    Bencherif, Sidi A.; Siegwart, Daniel J.; Srinivasan, Abiraman; Horkay, Ferenc; Hollinger, Jeffrey O.; Washburn, Newell R.; Matyjaszewski, Krzysztof

    2012-01-01

    A new method to prepare nanostructured hybrid hydrogels by incorporating well-defined poly(oligo (ethylene oxide) monomethyl ether methacrylate) (POEO300MA) nanogels of sizes 110–120 nm into a larger three-dimensional (3D) matrix was developed for drug delivery scaffolds for tissue engineering applications. Rhodamine B isothiocyanate-labeled dextran (RITC-Dx) or fluorescein isothiocyanate-labeled dextran (FITC-Dx)-loaded POEO300MA nanogels with pendant hydroxyl groups were prepared by activators generated electron transfer atom transfer radical polymerization (AGET ATRP) in cyclohexane inverse miniemulsion. Hydroxyl-containing nanogels were functionalized with methacrylated groups to generate photoreactive nanospheres. 1H NMR spectroscopy confirmed that polymerizable nanogels were successfully incorporated covalently into 3D hyaluronic acid-glycidyl methacrylate (HAGM) hydrogels after free radical photo-polymerization (FRP). The introduction of disulfide moieties into the polymerizable groups resulted in a controlled release of nanogels from cross-linked HAGM hydrogels under a reducing environment. The effect of gel hybridization on the macroscopic properties (swelling and mechanics) was studied. It is shown that swelling and nanogel content are independent of scaffold mechanics. In-vitro assays showed the nanostructured hybrid hydrogels were cytocompatible and the GRGDS (Gly–Arg–Gly–Asp–Ser) contained in the nanogel structure promoted cell–substrate interactions within 4 days of incubation. These nanostructured hydrogels have potential as an artificial extracellular matrix (ECM) impermeable to low molecular weight biomolecules and with controlled pharmaceutical release capability. Moreover, the nanogels can control drug or biomolecule delivery, while hyaluronic acid based-hydrogels can act as a macroscopic scaffold for tissue regeneration and regulator for nanogel release. PMID:19592087

  9. Nitroxide radical biostability in skin.

    Science.gov (United States)

    Fuchs, J; Freisleben, H J; Podda, M; Zimmer, G; Milbradt, R; Packer, L

    1993-10-01

    Nitroxide radicals are important chemical tools in dermatologic research (e.g., for studying biophysical properties of skin lipids and epidermal membranes with the method of electron paramagnetic resonance, EPR, spectroscopy). However, nitroxides may loose their paramagnetic properties in biological tissues, which could limit their usefulness in biomedical applications. We analyzed the biostability of various chemical types of nitroxide radicals in keratinocytes, epidermis homogenate, and intact skin. EPR signal loss of imidazoline, pyrrolidine, piperidine, and oxazolidine nitroxides is attributed to their reduction to the corresponding hydroxylamine. The rate of nitroxide reduction in skin varies considerably with nitroxide ring structure and substitution. The order of nitroxide stability in isolated human keratinocytes, mouse epidermis homogenate, and intact mouse and human skin is imidazoline > pyrrolidine > di-t-butylnitroxide (DTBN) > piperidine > oxazolidine. Cationic nitroxides are reduced much faster than neutral or anionic probes, presumably due to transmembrane electron shuttle or internalization. The results indicate that imidazoline- and pyrrolidine-type nitroxides should be used when high biostability of nitroxides is needed. Piperidine-type nitroxides are versatile probes for studying one-electron transfer reactions in skin. PMID:8225023

  10. Sensitization of Microorganisms and Enzymes by Radiation-Induced Selective Inorganic Radical Anions

    International Nuclear Information System (INIS)

    Bacterial survival and enzymatic inactivation were examined following exposure to radiolytically-generated radical anions, X-2 , where X = Cl, Br, I, or CNS. Depending on pH, radical anions react selectively or specifically with cysteine, tryptophan, tyrosine and histidine. Consequently, when one or more of these amino acids is crucial for enzymatic activity or bacterial survival and is attacked by a radical anion, a high degree or radiosensitization may be realized. Halide radical anions can form free chlorine, bromine or iodine. However, these bactericidal halogens are destroyed by reaction with the hydrated electron, e-aq, or at pHs > 9, as occurs, for example, when a medium saturated with nitrous oxide, N2O , and e-aq scavenger, is replaced by nitrogen or oxygen. Increasing concentration of other e-aq scavengers, such as phosphate buffer, promotes formation of halogen from halides. The conditions producing formation and élimination o f halogens in irradiated media m ust be appreciated to avoid confusing radiosensitization by X2 to X-2. Radiosensitization by radical anions o f several microorganisms: S. faecalis, S. typhimurium, E. coli, and M. radiodurens is described. A crucial amino acid for survival of S. faecalis appears to be tyrosine, while both tyrosine and tryptophan seem essential for recovery of S. typhimurium from effects of ionizing radiation. It is postulated that the radiosensitizing action o f radical anions involves inhibition of DNA repair of strand-breaks by depriving the cells of energy. In view of the high OH scavenging power of foods, it is concluded that the radiosensitization of bacteria and enzymes in foods by radical anions, except for special cases, is not practical. Rather, radical anions serve to identify crucial amino acids to radiosensitization mechanisms in model systems, and possibly in radiotherapy. (author)

  11. 213 nm Ultraviolet Photodissociation on Peptide Anions: Radical-Directed Fragmentation Patterns

    Science.gov (United States)

    Halim, Mohammad A.; Girod, Marion; MacAleese, Luke; Lemoine, Jérôme; Antoine, Rodolphe; Dugourd, Philippe

    2015-11-01

    Characterization of acidic peptides and proteins is greatly hindered due to lack of suitable analytical techniques. Here we present the implementation of 213 nm ultraviolet photodissociation (UVPD) in high-resolution quadrupole-Orbitrap mass spectrometer in negative polarity for peptide anions. Radical-driven backbone fragmentation provides 22 distinctive fragment ion types, achieving the complete sequence coverage for all reported peptides. Hydrogen-deficient radical anion not only promotes the cleavage of C?-C bond but also stimulates the breaking of N-C? and C-N bonds. Radical-directed loss of small molecules and specific side chain of amino acids are detected in these experiments. Radical containing side chain of amino acids (Tyr, Ser, Thr, and Asp) may possibly support the N-C? backbone fragmentation. Proline comprising peptides exhibit the unusual fragment ions similar to reported earlier. Interestingly, basic amino acids such as Arg and Lys also stimulated the formation of abundant b and y ions of the related peptide anions. Loss of hydrogen atom from the charge-reduced radical anion and fragment ions are rationalized by time-dependent density functional theory (TDDFT) calculation, locating the potential energy surface (PES) of ??* and repulsive ??* excited states of a model amide system.

  12. 213 nm Ultraviolet Photodissociation on Peptide Anions: Radical-Directed Fragmentation Patterns.

    Science.gov (United States)

    Halim, Mohammad A; Girod, Marion; MacAleese, Luke; Lemoine, Jérôme; Antoine, Rodolphe; Dugourd, Philippe

    2016-03-01

    Characterization of acidic peptides and proteins is greatly hindered due to lack of suitable analytical techniques. Here we present the implementation of 213 nm ultraviolet photodissociation (UVPD) in high-resolution quadrupole-Orbitrap mass spectrometer in negative polarity for peptide anions. Radical-driven backbone fragmentation provides 22 distinctive fragment ion types, achieving the complete sequence coverage for all reported peptides. Hydrogen-deficient radical anion not only promotes the cleavage of C?-C bond but also stimulates the breaking of N-C? and C-N bonds. Radical-directed loss of small molecules and specific side chain of amino acids are detected in these experiments. Radical containing side chain of amino acids (Tyr, Ser, Thr, and Asp) may possibly support the N-C? backbone fragmentation. Proline comprising peptides exhibit the unusual fragment ions similar to reported earlier. Interestingly, basic amino acids such as Arg and Lys also stimulated the formation of abundant b and y ions of the related peptide anions. Loss of hydrogen atom from the charge-reduced radical anion and fragment ions are rationalized by time-dependent density functional theory (TDDFT) calculation, locating the potential energy surface (PES) of ??* and repulsive ??* excited states of a model amide system. Graphical Abstract ?. PMID:26545767

  13. Prostatectomía radical laparoscópica versus robótica / Laparoscopic radical prostatectomy versus robotic

    Scientific Electronic Library Online (English)

    Felipe, Cáceres; Carlos, Sánchez; Luis, Martínez-Piñeiro; Angel, Tabernero; Sergio, Alonso; Jesús, Cisneros; Pedro Manuel, Cabrera Castillo; Mario, Álvarez Maestro; Mario, Martín Hernández; Manolo, Pérez-Utrilla Pérez; Jesús J. de la, Peña.

    2007-05-01

    Full Text Available Objetivo: La cirugía laparoscópica ha demostrado ser una buena alternativa a la cirugía abierta para el tratamiento del cáncer de próstata localizado. La cirugía robótica podría ser una opción terapéutica. Pretendemos hacer una evaluación de ambas técnicas, analizando una serie de parámetros que nos [...] permitan describir las ventajas e inconvenientes de ambas técnicas. Métodos: Hemos realizado una búsqueda en MED-LINE, revisando las mayores series de Prostatectomía Radical Laparoscópica (PRL) y Prostatectomía Radical Robótica (PRR)y hemos analizado los siguientes parámetros de cada técnica: resultados oncológicos, resultados funcionales, pérdida sanguínea, tasa de transfusión, tiempo quirúrgico, tasa de complicaciones, curva de aprendizaje y coste. Resultados: Ambas técnicas tienen la ventaja de ser mínimamente invasivas, con ventajas en la recuperación del paciente y en los resultados estéticos. La curva de aprendizaje es menor para la prostatectomía robótica, siendo de 10 a 20 casos para ésta y de 50 a 60 casos para la PRL. El análisis de los costes económicos es más favorable para la PRL que tiene un gasto en fungibles por paciente de 533 dólares, siendo éste de 1.705 dólares para la robótica. El precio del robot es de 1.200.000 dólares más un gasto anual de mantenimiento de 100.000 dólares (1). El tiempo operatorio es de 182 min. [141-250] para la robótica y de 234 min. [151-453] para la PRL. Dentro de una misma institución, como ocurre en Montsouris, los tiempos son muy parecidos tardando 155 min. para la robótica y 181 min. para la PRL (tabla 3). El sangrado medio operatorio es de 234 ml. [75-500] para la robótica y de 482 ml. [185-859] para la PRL, dependiendo de la técnica utilizada y de las distintas instituciones. El porcentaje de complicaciones es similar con ambas técnicas. El porcentaje de márgenes quirúrgicos positivos es de 20.6% para la PRL y del 19.24% para la robótica. No se pueden dar todavía resultados a largo plazo sobre recurrencia bioquímica del PSA debido a la corta existencia de ambas técnicas. La tasa de continencia para la PRL es de 56-100% y para la robótica del 70-98%. La tasa de potencia para la PRL es del 25-82% y para la robótica del 79-100%. No existen datos lo suficientemente claros para decir que existan diferencias significativas en cuanto a resultados funcionales. Es difícil evaluar la estancia postoperatoria ya que muchas veces depende de la política de la instituciones médicas, aunque en conjunto no parece que existan diferencias significativas entre ambas técnicas. Conclusiones: La ventajas intraoperatorias y postoperatorias son comparables con las dos técnicas. La prostatectomía robótica tiene una curva de aprendizaje más corta. Son necesarios estudios prospectivos con mayor seguimiento para poder comparar los resultados oncológicos y funcionales. El coste de la PRL es menor que el de la robótica. Abstract in english Objectives: Laparoscopic surgery has demonstrated that it is a good alternative to conventional surgery for the treatment of localized prostate cancer. Robotic surgery could be a therapeutic option. We try to evaluate both techniques, analyzing a series of parameters that allow us to describe the ad [...] vantages and disadvantages of both techniques. Methods: We performed a MEDLINE search and reviewed the main series of laparoscopic radical prostatectomy (LRP) and robotic radical prostatectomy (RRP). The parameters analyzed for each techniques were: oncological results, functional results, blood loss, transfusion rates, surgical times, complications rates, learning curve and cost. Results: Both techniques have the advantage of being minimally invasive, which results in better recovery and aesthetic results. The learning curve of the robotic prostatectomy is shorter, 10 to 20 cases in comparison with 50 to 60 for the LRP. Cost analysis is more favourable for LRP, with a single-use instrument expenditure of 533 dollars per patient in comparison with 1.705 dollars with the robot.

  14. Customers as Partners in Radical Service Innovation

    OpenAIRE

    Scupola, Ada; Nicolajsen, Hanne Westh

    2009-01-01

      Purpose- The main purpose of this paper is to investigate customer involvement and related challenges in radical service innovations in engineering consulting services Design/methodology/approach - The paper uses a case study approach and so called rich descriptions to investigate customer involvement, roles and related challenges and conditions in radical service innovations.Findings- One main finding is that customers can engage in radical service innovations in engineering consultancy se...

  15. Optimal pain management for radical prostatectomy surgery

    DEFF Research Database (Denmark)

    Joshi, Grish P; Jaschinski, Thomas; Bonnet, Francis; Kehlet, Henrik

    2015-01-01

    BACKGROUND: Increase in the diagnosis of prostate cancer has increased the incidence of radical prostatectomy. However, the literature assessing pain therapy for this procedure has not been systematically evaluated. Thus, optimal pain therapy for patients undergoing radical prostatectomy remains controversial. METHODS: Medline, Embase, and Cochrane Central Register of Controlled Trials were searched for studies assessing the effects of analgesic and anesthetic interventions on pain after radical...

  16. Oxygen free radical scavenger properties of dehydroepiandrosterone.

    OpenAIRE

    POLI, Giuseppe; BOCCUZZI, Giuseppe; Danni, Oliviero; TAMAGNO, Elena; ARAGNO, Manuela

    1998-01-01

    The microsomes from dehydroepiandrosterone (DHEA)-supplemented animals are good hydroxyl radical scavengers, as demonstrated through electron spin resonance and deoxyribose degradation. The ability of DHEA-supplemented microsomes to react with superoxide radical was also demonstrated through the inhibition of nitroblue-tetrazolium reduction determined by superoxide radicals produced in a hypoxanthine-xanthine oxidase system. DHEA-enriched microsomes, obtained from acutely DHEA-treated rats, b...

  17. Towards radical improvement in production systems

    OpenAIRE

    Gåsvaer, Daniel

    2013-01-01

    As the speed of change is increasing, it’s of great importance that manufacturing companies strive to achieve not only incremental improvements, but also radical improvements within their production systems. Thus, more research has to be focused on how to realize radical improvement. In accordance, the objective of the licentiate thesis is to, through theoretical and empirical work, increase the understanding about radical improvement in production and identify what elements need to be consid...

  18. Free radical scavenging properties of pyrimidine derivatives

    OpenAIRE

    Bano, Tabassum; Kumar, Nitin; Rupesh DUDHE

    2012-01-01

    Free radicals are well known for playing a dual role in our body- deleterious as well as beneficial. It includes a metabolic pathway for its generation. Oxidative stress in our body occurs due to excessive generation of free radicals and reduced level of antioxidants, but at low concentrations, these radicals help to perform normal physiological functions of the body. Scientific evidence suggests that antioxidants reduce the risk for chronic diseases including cancer and heart disease. This r...

  19. Customers as Partners in Radical Service Innovation

    OpenAIRE

    Scupola, Ada; Nicolajsen, Hanne Westh

    2009-01-01

      Purpose- The main purpose of this paper is to investigate customer involvement and related challenges in radical service innovations in engineering consulting services Design/methodology/approach - The paper uses a case study approach and so called rich descriptions to investigate customer involvement, roles and related challenges and conditions in radical service innovations.Findings- One main finding is that customers can engage in radical service innovations in engineering consultancy se...

  20. El radical primo en sistemas triples

    OpenAIRE

    Jiménez B., Luis Rafael

    2012-01-01

    El objeto de este artículo es dar una definición del radical primo para un sistema triple y probar que satisface las propiedades básicas que debe tener un radical. Para facilitar la lectura del artículo lo dividiremos en tres secciones. En la primera sección presentaremos los prerrequisitos necesarios sobre sistemas triples, en la segunda daremos la definición del radical y desarrollaremos sus propiedades y en la tercera estudiaremos sus relaciones con nilpotencia. Este trabajo nació de una s...