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Sample records for superoxide radical anions

  1. Methylglyoxal as a scavenger for superoxide anion-radical.

    Science.gov (United States)

    Shumaev, K B; Lankin, V Z; Konovalova, G G; Grechnikova, M A; Tikhaze, A K

    2016-07-01

    Methylglyoxal at a concentration of 5 mM caused a significant inhibition of superoxide anion radical (O2 (·-)) comparable to the effect of Tirone. In the process of O2 (·-) generation in the system of egg phosphatidylcholine liposome peroxidation induced by the azo-initiator AIBN, a marked inhibition of chemiluminescence in the presence of 100 mM methylglyoxal was found. At the same time, methylglyoxal did not inhibit free radical peroxidation of low-density lipoprotein particles, which indicates the absence of interaction with methylglyoxal alkoxyl and peroxyl polyenoic lipid radicals. These findings deepen information about the role of methylglyoxal in the regulation of free radical processes.

  2. Inhibitory effects of chitosan on superoxide anion radicals and lipid free radicals

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    With the electron spin resonance (ESR) technique, the inhibitory effects of chitosan on superoxide anion radicals and linoleic acid lipid radicals were found. The inhibitory ratio E for these two kinds of radicals is in proportion to the concentration of chitosan. It was also observed that E for linoleic acid lipid radicals increased with the increase of the degree of deacetylation and decreased with the increase of the molecular weight of chitosan.

  3. Superoxide Anion Radical Scavenging Ability of Quaternary Ammonium Salt of Chitosan

    Institute of Scientific and Technical Information of China (English)

    Xiao Yan ZHU; Jian Min WU; Zhi Shen JIA

    2004-01-01

    A series of N-alkyl or N-aryl chitosan quaternary ammonium salt were prepared using 96% deacetylated chitosan. Their scavenging activities against superoxide anion radical were investigated by chemiluminescence. The IC50 values of these compounds range from 280 to 880 μg/mL, which should be attributed to their different substitutes.

  4. Mechanism of Action of Sulforaphane as a Superoxide Radical Anion and Hydrogen Peroxide Scavenger by Double Hydrogen Transfer: A Model for Iron Superoxide Dismutase.

    Science.gov (United States)

    Prasad, Ajit Kumar; Mishra, P C

    2015-06-25

    The mechanism of action of sulforaphane as a scavenger of superoxide radical anion (O2(•-)) and hydrogen peroxide (H2O2) was investigated using density functional theory (DFT) in both gas phase and aqueous media. Iron superoxide dismutase (Fe-SOD) involved in scavenging superoxide radical anion from biological media was modeled by a complex consisting of the ferric ion (Fe(3+)) attached to three histidine rings. Reactions related to scavenging of superoxide radical anion by sulforaphane were studied using DFT in the presence and absence of Fe-SOD represented by this model in both gas phase and aqueous media. The scavenging action of sulforaphane toward both superoxide radical anion and hydrogen peroxide was found to involve the unusual mechanism of double hydrogen transfer. It was found that sulforaphane alone, without Fe-SOD, cannot scavenge superoxide radical anion in gas phase or aqueous media efficiently as the corresponding reaction barriers are very high. However, in the presence of Fe-SOD represented by the above-mentioned model, the scavenging reactions become barrierless, and so sulforaphane scavenges superoxide radical anion by converting it to hydrogen peroxide efficiently. Further, sulforaphane was found to scavenge hydrogen peroxide also very efficiently by converting it into water. Thus, the mechanism of action of sulforaphane as an excellent antioxidant has been unravelled.

  5. Reactions of superoxide dismutases with HS(-)/H2S and superoxide radical anion: An in vitro EPR study.

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    Bolić, Bojana; Mijušković, Ana; Popović-Bijelić, Ana; Nikolić-Kokić, Aleksandra; Spasić, Snežana; Blagojević, Duško; Spasić, Mihajlo B; Spasojević, Ivan

    2015-12-01

    Interactions of hydrogen sulfide (HS(-)/H2S), a reducing signaling species, with superoxide dimutases (SOD) are poorly understood. We applied low-T EPR spectroscopy to examine the effects of HS(-)/H2S and superoxide radical anion O2.- on metallocenters of FeSOD, MnSOD, and CuZnSOD. HS(-)/H2S did not affect FeSOD, whereas active centers of MnSOD and CuZnSOD were open to this agent. Cu(2+) was reduced to Cu(1+), while manganese appears to be released from MnSOD active center. Untreated and O2.- treated FeSOD and MnSOD predominantly show 5 d-electron systems, i.e. Fe(3+) and Mn(2+). Our study provides new details on the mechanisms of (patho)physiological effects of HS(-)/H2S.

  6. Superoxide Anion Radical Production in the Tardigrade Paramacrobiotus richtersi, the First Electron Paramagnetic Resonance Spin-Trapping Study.

    Science.gov (United States)

    Savic, Aleksandar G; Guidetti, Roberto; Turi, Ana; Pavicevic, Aleksandra; Giovannini, Ilaria; Rebecchi, Lorena; Mojovic, Milos

    2015-01-01

    Anhydrobiosis is an adaptive strategy that allows withstanding almost complete body water loss. It has been developed independently by many organisms belonging to different evolutionary lines, including tardigrades. The loss of water during anhydrobiotic processes leads to oxidative stress. To date, the metabolism of free radicals in tardigrades remained unclear. We present a method for in vivo monitoring of free radical production in tardigrades, based on electron paramagnetic resonance and spin-trap DEPMPO, which provides simultaneous identification of various spin adducts (i.e., different types of free radicals). The spin trap can be easily absorbed in animals, and tardigrades stay alive during the measurements and during 24-h monitoring after the treatment. The results show that hydrated specimens of the tardigrade Paramacrobiotus richtersi produce the pure superoxide anion radical ((•)O2(-)). This is an unexpected result, as all previously examined animals and plants produce both superoxide anion radical and hydroxyl radical ((•)OH) or exclusively hydroxyl radical.

  7. A study on scavenging effects of Chinese medicine on superoxide anion radicals by pulse radiolysis

    Energy Technology Data Exchange (ETDEWEB)

    Li Fengmei; Liu Andong; Gu Hongchun; Di Shaojie (Beijing Normal Univ., BJ (China). Inst. of Low Energy Nuclear Physics)

    A study on scavenging and dismutation effects on superoxide anion radical ([center dot]O[sub 2][sup -]) using two Chinese antiaging medicines - Salvia miltiorrhiza injection (S.M.) and Sulekang capsule (S.C.) was carried out using pulse radiolysis. The absorption spectra of [center dot] OH[sub 2][sup -] was redetermined by radiolysis of an aqueous solution of sodium format. The absorption maximum is at about 250 nm. The results suggested that S.M. and S.C. can dismutate and scavenge [center dot]O[sub 2][sup -]. The experimental scavenging rates of S.M. (150[mu]g/ml) and S.C. (250[mu]g/ml) were 89.6% and 69.5% respectively. (author).

  8. PCL assay application in superoxide anion-radical scavenging capacity of tea Camellia sinensis extracts

    Directory of Open Access Journals (Sweden)

    Anna Gramza-Michałowska

    2015-12-01

    Full Text Available Background. Plant polyphenols are known for their limiting of adverse effects on reactive oxygen species (ROS in biological systems. The photochemiluminescence (PCL assay allows to evaluate the antiradical activity of a compound in the presence of a superoxide anion-radical (O •-, which is one of the ROS directly associated with the human body. In this work, determination of the superoxide anion radical scavenging ac- tivity of different tea extracts using the PCL assay was performed. Material and methods. Investigations were conducted on different tea leaves extracts. The study included five kinds of tea leaves subjected to aqueous and ethanol extraction procedure. Catechins content was evalu- ated using HPLC. Antiradical activity of the samples was conducted with use of Photochem assay. Results. Analysis of total catechins content in tea aqueous extracts enabled them to be arranged as follows: yellow > green > white > red > black, while for ethanol extracts it was: yellow = green > white > red > black. The examined tea extracts were ranked from highest to lowest water-soluble antioxidative capacity (ACW values as follows: yellow > green > white > red > black. The results of lipid-soluble antioxidative capacity (ACL values for aqueous extracts were similar; however, were approximately 50% lower than those pre- sented as ACW. The second examined group were ethanol extracts, which ranked for ACW values: yellow > green = red = white > black, while ACL values ranked as follows: yellow > white = black = red > green. PCL assay results were correlated with total catechin content in aqueous extracts. Conclusions. Antiradical activity of different tea leaves extracts in PCL assay, showed that the highest activ- ity was found in extracts of yellow tea; the lowest, however, was identified in black tea extracts.

  9. 1,1-Diphenyl-2-picrylhydrazyl radical and superoxide anion scavenging activity of Rhizophora mangle (L. bark

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    Janet Calero Sánchez

    2010-01-01

    Full Text Available Background: Rhizophora mangle (L. produce a variety of substances that possesses pharmacological actions. Although it shown antioxidant properties in some assays, there is no available information about its effect on some free radical species. So the objective of the present research is to evaluate the DPPH radical and superoxide anion scavenging properties of R. mangle extract and its polyphenol fraction. Methods: Rhizophora mangle (L. bark aqueous extract and its major constituent, polyphenols fraction, were investigated for their antioxidant activities employing 2 in vitro assay systems: 1,1-diphenyl-2-picrylhydrazyl (DPPH and superoxide anion radicals scavenging. Results: IC 50 for DPPH radical-scavenging activity was 6.7 μg tannins/mL for extract and 7.6 μg tannins/mL for polyphenolic fraction. The extract showed better activity than its fraction (P < 0.05 in the DPPH radicals reducing power. Polyphenolic fraction exhibited better superoxide anion scavenging ability (IC 50 = 21.6 μg tannins/mL than the extract (IC 50 = 31.9 μg tannins/mL. Antioxidant activities of both samples increased with the rise of tannins concentration. The comparison of regression lines showed significant differences (P < 0.05 between extract and its polyphenolic fraction in both assays, indicating that extract was more effective in DPPH radical scavenging than its fraction at tannin concentrations below the crossing point of both lines, while that fraction was more effective than extract inhibiting the superoxide anions generation. Conclusions: R. mangle aqueous extract showed a potent antioxidant activity, achieved by the scavenging ability observed against DPPH radicals and superoxide anions. Regarding its polyphenolic composition, the antioxidant effects observed in this study are due, most probably, to the presence of polyphenolic compounds.

  10. Ferrous Ion Chelating, Superoxide Anion Radical Scavenging and Tyrosinase Inhibitory Properties of Pure and Commercial Essential Oils of Anetrhum Graveolens

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    Sh Darvish Alipour Astaneh

    2013-04-01

    Full Text Available Introduction: Despite slight toxicities of essential oils, they are not under strict control in many countries. Anethum graveolens is widely consumed and its essential oils are at public reach. This study was designed to study essential oils of Anethum graveolens. Methods: The biological properties of pure and commercial essential oils of Anethum graveolens were investigated. In fact, Ferrous ion chelating activity, superoxide anion radical scavenging property, tyrosinase inhibition and total flavonoids of the oils were determined. Results: Chelating activity of 7.8 µg of EDTA was equivalent to 2 µg of the pure oil. The oils had superoxide anion radical scavenging activities which may be related to their total phenol and flavonoid contents. IC50 of ferrous ion chelating, antityrosiase and superoxide anion radical scavenging activities of pure and commercial oils were 1.3, 1.4, 1 and (171.6, 589, 132 µg respectively. Antityrosiase activity of 6.4 µg pure oil was equal to 1000 µg of the commercial oil. Conclusion: Anethum possesses antioxidative and free radical scavenging properties. This oil chelates ferrous ions and superoxide radicals. It is effective in formation of reactive toxic products. Anethum has good potentials regarding its applications in food and drug industries.

  11. Superoxide Anion Radical: Generation and Detection in Cellular and Non-Cellular Systems.

    Science.gov (United States)

    Chiste, Renan Campos; Freitas, Marisa; Mercadante, Adriana Zerlotti; Fernandes, Eduarda

    2015-01-01

    The production of superoxide anion radical (O2•(-)) is essential for the life of aerobic organisms. This free radical acts as a signaling molecule, regulating numerous biological processes including apoptosis, aging, and senescence. Nevertheless, when overproduction of O2•(-) occurs and/or antioxidant defences are deficient, oxidative stress may develop, damaging important biomolecules and altering their physiological function. These effects have been associated to the development of several diseases. Scavenging of O2•(-) has been used as a hallmark to test the antioxidant capacity of several types of compounds in cellular and non-cellular systems. However, despite the pathophysiological importance of O2•(-), the information about its endogenous and/or chemical generation and detection is dispersed and there are no reports that concisely cover the information in an integrated form. This gap can explain the limitations attributed to the currently used systems, namely in what concerns the selectivity, specificity and validation. This review attempts to provide a critical assessment of the available O2•(-) generating and detection, both in endogenous and chemical systems, scrutinizing its advantages and limitations in order to facilitate the choice and implementation of the O2•(-) generator and/or detection method that better fits the researchers' objectives.

  12. [Production of superoxide anion radical and nitric oxide in renal tissues sutured with different surgical suture material].

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    Kostenko, V O; Tsebrzhins'kii, O I

    2000-01-01

    The generation of superoxide anion radicals (in mitochondria, microsomes and under respiratory burst of leucocytes) and nitric oxide (NO) in renal tissue has been studied in the experiment with white rats, which had been carried out nephrotomy with following usage for suture such absorbable surgical threads as plain and chromic catgut, biofil (of dura mater spinalis of the cattle), Dexon II (polyglycolic acid) and biofil modified with aethonium, succinate and mexidol. The research proves the use of plai and chromic catgut leads to the development longer oxidative stress with increasing of cytotoxic agents production (superoxide anion and NO). The risk of longitudinal oxidative stress decreases under the use of biofil suture modified with biological active compounds (aethonium, succinate and mexidol). In this case, the generation of superoxide anion radicals in mitochondria and microsomes is normalised earlier. The superoxide generation with respiratory burst of leucocytes and NO production decreases in 14 day of postoperative period under the use of biofil suture modified with succinate and mexidol.

  13. Superoxide radical anion scavenging and dismutation by some Cu2+ and Mn2+ complexes: A pulse radiolysis study

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    Joshi, Ravi

    2017-10-01

    Copper (Cu) and manganese (Mn) ions are catalytic centers, in complexed form, in scavenging and dismutation process of superoxide radicals anion (O2.-) by superoxide dismutase enzyme. In the present work, fast reaction kinetics and mechanism of scavenging and dismutation of O2.- by Cu2+, Mn2+ and their complexes formed with some natural ligands have been studied using pulse radiolysis technique. Catechol, gentisic acid, tetrahydroxyquinone, tyrosine, tryptophan, embelin and bilirubin have been used as low molecular weight natural ligands for Cu2+ and Mn2+ to understand superoxide radical scavenging and dismutation reactions. These complexes have been found to be efficient scavengers of O2.- (k 107-109 M-1 s-1). The effects of nature of metal ion and ligand, and stoichiometry of complex on scavenging reaction rate constants are reported. Higher scavenging rate constants have been observed with complexes of: (1) Cu2+ as compared to Mn2+, and (2) at [ligand]/[metal] ratio of one as compared to two. A clear evidence of O2.- dismutation by free metal ions and some of the complexes has been observed. The study suggests that complexes of Cu2+ and Mn2+ with small natural ligands can also act as SOD mimics.

  14. Superoxide anion radicals induce IGF-1 resistance through concomitant activation of PTP1B and PTEN.

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    Singh, Karmveer; Maity, Pallab; Krug, Linda; Meyer, Patrick; Treiber, Nicolai; Lucas, Tanja; Basu, Abhijit; Kochanek, Stefan; Wlaschek, Meinhard; Geiger, Hartmut; Scharffetter-Kochanek, Karin

    2015-01-01

    The evolutionarily conserved IGF-1 signalling pathway is associated with longevity, metabolism, tissue homeostasis, and cancer progression. Its regulation relies on the delicate balance between activating kinases and suppressing phosphatases and is still not very well understood. We report here that IGF-1 signalling in vitro and in a murine ageing model in vivo is suppressed in response to accumulation of superoxide anions (O2∙-) in mitochondria, either by chemical inhibition of complex I or by genetic silencing of O2∙--dismutating mitochondrial Sod2. The O2∙--dependent suppression of IGF-1 signalling resulted in decreased proliferation of murine dermal fibroblasts, affected translation initiation factors and suppressed the expression of α1(I), α1(III), and α2(I) collagen, the hallmarks of skin ageing. Enhanced O2∙- led to activation of the phosphatases PTP1B and PTEN, which via dephosphorylation of the IGF-1 receptor and phosphatidylinositol 3,4,5-triphosphate dampened IGF-1 signalling. Genetic and pharmacologic inhibition of PTP1B and PTEN abrogated O2∙--induced IGF-1 resistance and rescued the ageing skin phenotype. We thus identify previously unreported signature events with O2∙-, PTP1B, and PTEN as promising targets for drug development to prevent IGF-1 resistance-related pathologies.

  15. Sonochemiluminescence of lucigenin: Evidence of superoxide radical anion formation by ultrasonic irradiation

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    Matsuoka, Masanori; Takahashi, Fumiki; Asakura, Yoshiyuki; Jin, Jiye

    2016-07-01

    The sonochemiluminescence (SCL) behavior of lucigenin (Luc2+) has been studied in aqueous solutions irradiated with 500 kHz ultrasound. Compared with the SCL of a luminol system, a tremendously increased SCL intensity is observed from 50 µM Luc2+ aqueous solution (pH =11) when small amounts of coreactants such as 2-propanol coexist. It is shown that SCL intensity strongly depends on the presence of dissolved gases such as air, O2, N2, and Ar. The highest SCL intensity is obtained in an O2-saturated solution, indicating that molecular oxygen is required to generate SCL. Since SCL intensity is quenched completely in the presence of superoxide dismutase (SOD), an enzyme that can catalyze the disproportionation of O2 •-, the generation of O2 •- in the ultrasonic reaction field is important in the SCL of Luc2+. In this work, the evidence of O2 •- production is examined by a spectrofluorometric method using 2-(2-pyridyl)benzothiazoline as the fluorescent probe. The results indicate that the yield of O2 •- is markedly increased in the O2-saturated solutions when a small amount of 2-propanol coexists, which is consistent with the results of SCL measurements. 2-Propanol in the interfacial region of a cavitation bubble reacts with a hydroxyl radical (•OH) to form a 2-propanol radical, CH3C•(OH)CH3, which can subsequently react with dissolved oxygen to generate O2 •-. The most likely pathways for SCL as well as the spatial distribution of SCL in a microreactor are discussed in this study.

  16. Peroxynitrite mediates active site tyrosine nitration in manganese superoxide dismutase. Evidence of a role for the carbonate radical anion.

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    Surmeli, N Basak; Litterman, Nadia K; Miller, Anne-Frances; Groves, John T

    2010-12-08

    carbonate radical anion (•CO3(-)) in MnSOD nitration by PN. We also observed that the nitration of Tyr34 caused inactivation of the enzyme, while nitration of Tyr9 and Tyr11 did not interfere with the superoxide dismutase activity. The loss of MnSOD activity upon Tyr34 nitration implies that the responsible reagent in vivo is peroxynitrite, acting either directly or through the action of •CO3(-).

  17. Proton transfer from 1,4-pentadiene to superoxide radical anion: a QTAIM analysis

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    Angela Rodríguez-Serrano

    2014-04-01

    Full Text Available We studied the bis-allylic proton transferreaction from 1,4-pentadiene to superoxideradical anion (O2·־. Minima andtransition state geometries, as well asthermochemical parameters were computedat the B3LYP/6-311+G(3df,2plevel of theory. The electronic wavefunctions of reactants, intermediates,and products were analyzed within theframework of the Quantum Theory ofAtoms in Molecules. The results showthe formation of strongly hydrogen bondedcomplexes between the 1,4-pentadien-3-yl anion and the hydroperoxylradical as the reaction products. Theseproduct complexes (PCs are more stablethan the isolated reactants and muchmore stable than the isolated products.This reaction occurs via pre-reactivecomplexes which are more stable thanthe PCs and the transition states. This isin agreement with the fact that the netproton transfer reaction that leads to freeproducts is an endothermic and nonspontaneousprocess.

  18. Viral infection correlated with superoxide anion radicals production and natural and synthetic copper complexes.

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    Tomas, E; Popescu, A; Titire, A; Cajal, N; Cristescu, C; Tomas, S

    1989-01-01

    Studies conducted on asymmetric triazine derivatives synthetized at the Chemical and Pharmaceutical Research Institute showed that products S1, S16, S17, S19, S20 and S22 have a remarkable O2- radical scavenger activity. Among these derivatives, the product S1 is the most efficient as an antiviral agent.

  19. The activity of 3- and 7-hydroxyflavones as scavengers of superoxide radical anion generated from photo-excited riboflavin

    Energy Technology Data Exchange (ETDEWEB)

    Montana, P.; Pappano, N.; Debattista, N. [Universidad Nacional de San Luis, Area de Quimica Fisica, San Luis (Argentina); Avila, V.; Posadaz, A.; Bertolotti, S.G.; Garcia, N.A. [Universidad Nacional de Rio Cuarto, Dto. de Quimica, Rio Cuarto (Argentina)

    2003-08-01

    The visible-light irradiation of the system Riboflavin plus 3-hydroxyflavone or plus 7-hydroxyflavone, under aerobic conditions, produces a series of competitive processes that depend on the relative concentrations of the pigment and the flavones. The picture comprises photochemical mechanisms that potentially operate in nature. They mainly include the quenching of Rf singlet ({sup 1}Rf*) and triplet ({sup 3}Rf*) excited states (with bimolecular rate constants in the order of 10{sup 9} M{sup -1} s{sup -1}) and superoxide radical anion-mediated reactions. The participation of the oxidative species singlet molecular oxygen was not detected. The overall result shows chemical transformations in both Rf and 3-hydroxyflavone. No experimental evidence was found indicating any chemical reaction involving 7-hydroxyflavone. The fate of the pigment also depends on the amount of the dissolved flavonoid. At 50 mM concentrations of these compounds or higher, practically no photochemistry occurs, owing to the extensive quenching of ({sup 1}Rf*) When the concentration of the flavones is in the mM range or lower, ({sup 3}Rf*) is photogenerated. Then, the excited triplet species can be quenched mainly by the flavones through an electron-transfer process, yielding the semireduced pigment. The latter interacts with dissolved oxygen producing O{sub 2}{sup .-}, which reacts with both the pigment and 3-hydroxyflavone. In summary, 3-hydroxyflavone and 7-hydroxyflavone participate in the generation of superoxide ion in an Rf-sensitized process, and simultaneously 3-hydroxyflavone constitutes a degradable quencher of the oxidative species. (author)

  20. Superoxide anion radical (O2(-)) degrades methylmercury to inorganic mercury in human astrocytoma cell line (CCF-STTG1).

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    Mailloux, Ryan J; Yumvihoze, Emmanuel; Chan, Hing Man

    2015-09-05

    Methylmercury (MeHg) is a global pollutant that is affecting the health of millions of people worldwide. However, the mechanism of MeHg toxicity still remains somewhat elusive and there is no treatment. It has been known for some time that MeHg can be progressively converted to inorganic mercury (iHg) in various tissues including the brain. Recent work has suggested that cleavage of the carbon-metal bond in MeHg in a biological environment is facilitated by reactive oxygen species (ROS). However, the oxyradical species that actually mediates this process has not been identified. Here, we provide evidence that superoxide anion radical (O2(-)) can convert MeHg to iHg. The calculated second-order rate constant for the degradation of 1μM MeHg by O2(-) generated by xanthine/xanthine oxidase was calculated to be 2×10(5)M(-1)s(-1). We were also able to show that this bioconversion can proceed in intact CCF-STTG1 human astrocytoma cells exposed to paraquat (PQ), a O2(-) generating viologen. Notably, exposure of cells to increasing amounts of PQ led to a dose dependent increase in both MeHg and iHg. Indeed, a 24h exposure to 500μM PQ induced a ∼13-fold and ∼18-fold increase in intracellular MeHg and iHg respectively. These effects were inhibited by superoxide dismutase mimetic MnTBAP. In addition, we also observed that a 24h exposure to a biologically relevant concentration of MeHg (1μM) did not induce cell death, oxidative stress, or even changes in cellular O2(-) and H2O2. However, co-exposure to PQ enhanced MeHg toxicity which was associated with a robust increase in cell death and oxidative stress. Collectively our results show that O2(-) can bioconvert MeHg to iHg in vitro and in intact cells exposed to conditions that simulate high intracellular O2(-) production. In addition, we show for the first time that O2(-) mediated degradation of MeHg to iHg enhances the toxicity of MeHg by facilitating an accumulation of both MeHg and iHg in the intracellular

  1. Ionol (BHT) produces superoxide anion.

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    Smirnova, E G; Lyubimov, Yu I; Malinina, T G; Lyubimova, E Yu; Alexandrushkina, N I; Vanyushin, B F; Kolesova, G M; Yaguzhinsky, L S

    2002-11-01

    In aqueous medium etiolated wheat seedlings release superoxide anion (O2*-). Interaction of a synthetic antioxidant, butylated hydroxytoluene (BHT, ionol), with oxygen in the aqueous medium is accompanied by O2*- formation. This suggests that under certain conditions BHT behaves as a prooxidant. A natural antioxidant, superoxide dismutase (SOD), and also a wound healing preparation, emulsified denatured placenta (EDP), do not exhibit the prooxidant properties. In contrast to BHT, they reduce O2*- production by the etiolated wheat seedling system.

  2. The carbonate radical anion-induced covalent aggregation of human copper, zinc superoxide dismutase, and alpha-synuclein: intermediacy of tryptophan- and tyrosine-derived oxidation products.

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    Zhang, Hao; Andrekopoulos, Christopher; Joseph, Joy; Crow, John; Kalyanaraman, B

    2004-06-01

    In this review, we describe the free radical mechanism of covalent aggregation of human copper, zinc superoxide dismutase (hSOD1). Bicarbonate anion (HCO3-) enhances the covalent aggregation of hSOD1 mediated by the SOD1 peroxidase-dependent formation of carbonate radical anion (CO3*-), a potent and selective oxidant. This species presumably diffuses out the active site of hSOD1 and reacts with tryptophan residue located on the surface of hSOD1. The oxidative degradation of tryptophan to kynurenine and N-formyl kynurenine results in the covalent crosslinking and aggregation of hSOD1. Implications of oxidant-mediated aggregation of hSOD1 in the increased cytotoxicity of motor neurons in amyotrophic lateral sclerosis are discussed.

  3. Superoxide generated by pyrogallol reduces highly water-soluble tetrazolium salt to produce a soluble formazan: a simple assay for measuring superoxide anion radical scavenging activities of biological and abiological samples.

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    Xu, Chen; Liu, Shu; Liu, Zhiqiang; Song, Fengrui; Liu, Shuying

    2013-09-02

    Superoxide anion radical (O2(˙-)) plays an important role in several human diseases. The xanthine/xanthine oxidase system is frequently utilized to produce O2(˙-). However, false positive results are easily got by using this system. The common spectrophotometric probes for O2(˙-) are nitroblue tetrazolium (NBT) and cytochrome c. Nevertheless, the application of NBT method is limited because of the water-insolubility of NBT formazan and the assay using cytochrome c lacks sensitivity and is not suitable for microplate measurement. We overcome these problems by using 1,2,3-trihydroxybenzene (pyrogallol) as O2(˙-)-generating system and a highly water-soluble tetrazolium salt, 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium sodium salt (WST-1) which can be reduced by superoxide anion radical to a stable water-soluble formazan with a high absorbance at 450 nm. The method is simple, rapid and sensitive. Moreover, it can be adapted to microplate format. In this study, the O2(˙-) scavenging activities of superoxide dismutase (SOD), L-ascorbic acid, N-acetyl-L-cysteine (NAC), albumin from human serum, flavonoids and herbal extracts were assessed by using this method. Meanwhile, the activities of tissue homogenates and serum were determined by using this validated method. This method, applicable to tissue homogenates, serum and herbal extracts, proved to be efficient for measuring O2(˙-) scavenging activities of biological and abiological samples.

  4. Competitive Deprotonation and Superoxide [O2 -•] Radical-Anion Adduct Formation Reactions of Carboxamides under Negative-Ion Atmospheric-Pressure Helium-Plasma Ionization (HePI) Conditions

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    Hassan, Isra; Pinto, Spencer; Weisbecker, Carl; Attygalle, Athula B.

    2016-03-01

    Carboxamides bearing an N-H functionality are known to undergo deprotonation under negative-ion-generating mass spectrometric conditions. Herein, we report that N-H bearing carboxamides with acidities lower than that of the hydroperoxyl radical (HO-O•) preferentially form superoxide radical-anion (O2 -•) adducts, rather than deprotonate, when they are exposed to the glow discharge of a helium-plasma ionization source. For example, the spectra of N-alkylacetamides show peaks for superoxide radical-anion (O2 -•) adducts. Conversely, more acidic amides, such as N-alkyltrifluoroacetamides, preferentially undergo deprotonation under similar experimental conditions. Upon collisional activation, the O2 -• adducts of N-alkylacetamides either lose the neutral amide or the hydroperoxyl radical (HO-O•) to generate the superoxide radical-anion ( m/z 32) or the deprotonated amide [ m/z (M - H)-], respectively. For somewhat acidic carboxamides, the association between the two entities is weak. Thus, upon mildest collisional activation, the adduct dissociates to eject the superoxide anion. Superoxide-adduct formation results are useful for structure determination purposes because carboxamides devoid of a N-H functionality undergo neither deprotonation nor adduct formation under HePI conditions.

  5. Construction of a highly sensitive non-enzymatic sensor for superoxide anion radical detection from living cells.

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    Liu, Yuelin; Liu, Xiuhui; Liu, Yidan; Liu, Guoan; Ding, Lan; Lu, Xiaoquan

    2017-04-15

    A novel non-enzymatic superoxide anion (O2•(-)) sensor was fabricated based on Ag nanoparticles (NPs)/L-cysteine functioned carbon nanotubes (Cys-MWCNTs) nanocomposites and used to measure the release of O2•(-) from living cells. In this strategy, AgNPs could be uniformly electrodeposited on the MWCNTs surface with average diameter of about 20nm as exhibited by scanning electronmicroscopy (SEM). Electrochemical study demonstrated that the AgNPs/Cys-MWCNTs modified glassy carbon electrode exhibited excellent catalytic activity toward the reduction of O2•(-) with a super wide linear range from 7.00×10(-11) to 7.41×10(-5)M and a low detection limit (LOD) of 2.33×10(-11)M (S/N=3). Meanwhile, the mechanism for O2•(-) reduction was also proposed for the first time. Importantly, this novel non-enzymatic O2•(-) sensor can detect O2•(-) release from cancer cells under both the external stimulation and the normal condition, which has the great potential application in clinical diagnostics to assess oxidative stress of living cells.

  6. Ursodeoxycholic acid and superoxide anion

    Institute of Scientific and Technical Information of China (English)

    Predrag Ljubuncic; Omar Abu-Salach; Arieh Bomzon

    2005-01-01

    AIM: To investigate the ability of ursodeoxycholic acid (UDCA) to scavenge superoxide anion (O2-).METHODS: We assessed the ability of UDCA to scavenge (O2-) generated by xanthine-xanthine oxidase (X-XO) in a cell-free system and its effect on the rate of O2--induced ascorbic acid (AA) oxidation in hepatic post-mitochondrial supernatants.RESULTS: UDCA at a concentration as high as 1 mmol/Ldid not impair the ability of the X-XO system to generate O2-, but could scavenge O2- at concentrations of 0.5 and 1 mmol/L, and decrease the rate of AA oxidation at a concentration of 100 μmol/L.CONCLUSION: UDCA can scavenge O2-, an action that may be beneficial to patients with primary biliary cirrhosis.

  7. Corticosteroids increase superoxide anion production by rat liver microsomes.

    Science.gov (United States)

    Nelson, D H; Ruhmann-Wennhold, A

    1975-01-01

    Superoxide anion production by liver microsomes from intact, adrenalectomized, and cortisoltreated adrenalectomized rats has been determined. The amount formed was roughly proportionate to the amount of cortisol given, and a similar response was seen in the activity of NADPH-cytochrome c reductase. The amount of measurable superoxide anion was markedly reduced by the addition of superoxide dismutase. The increased production of this potent free radical with cortisol therapy suggests that its formation may contribute to some of the harmful effects of corticosteroids given in more than physiologic amounts. PMID:239969

  8. 氧脱木素过程中超氧阴离子自由基的控制%Regulation of Superoxide Anion Radical During the Oxygen Delignification Process

    Institute of Scientific and Technical Information of China (English)

    曹石林; 詹怀宇; 付时雨; 陈礼辉

    2007-01-01

    In this study, the superoxide anion radicals were generated by the auto-oxidation of 1,2,3-trihydroxybenzene and determined by UV spectrophotometry, and the reaction was found to be facilitated by anthraquinone-2-sulfonic acid sodium salt. The bamboo kraft pulps were treated by the 1,2,3-trihydroxybenzene auto-oxidation method or the 1,2,3-trihydroxybenzene auto-oxidation combined with anthraquinone-2-suffonic acid sodium salt to show the effect of the superoxide anion radicals during the oxygen delignification of bamboo kraft pulp and the enhancing affect of anthraquinone compounds as an additive on delignification. The results indicated that the superoxide anion radicals could react with lignin and remove it from pulp with negligible damage on cellulose, and the anthraquinone-2-sulfonic acid sodium salt could facilitate the generation of superoxide anion radical to enhance delignification of pulps. The oxygen delignification selectivity could be improved using the 1,2,3-trihydroxybenzene auto-oxidation system combined with anthraquinone-2-sulfonic acid sodium salt.

  9. Effect of insulin, the glutathione system, and superoxide anion radical in modulation of lipolysis in adipocytes of rats with experimental diabetes.

    Science.gov (United States)

    Ivanov, V V; Shakhristova, E V; Stepovaya, E A; Nosareva, O L; Fedorova, T S; Ryazantseva, N V; Novitsky, V V

    2015-01-01

    Spontaneous lipolysis was found to be increased in adipocytes of rats with alloxan-induced diabetes. In addition, isoproterenol-stimulated hydrolysis of triacylglycerols was inhibited against the background of oxidative stress and decreased redox-status of cells. A decrease in the ability of insulin to inhibit isoproterenol-stimulated lipolysis in adipocytes that were isolated from adipose tissue of rats with experimental diabetes was found, which shows a disorder in regulation of lipolysis in adipocytes by the hormone in alloxan-induced diabetes. Based on these findings, we concluded that there is an influence of reactive oxygen species, superoxide anion radical in particular, and redox potential of the glutathione system on molecular mechanisms of change in lipolysis intensity in rat adipocytes in alloxan-induced oxidative stress. Activation of spontaneous lipolysis under conditions of oxidative stress might be a reason for the high concentration of free fatty acids in blood plasma in experimental diabetes, and this may play a significant role in development of insulin resistance and appearance of complications of diabetes.

  10. Healing of colonic ischemic anastomoses in the rat: role of superoxide radicals.

    Science.gov (United States)

    Garcia, J G; Criado, F J; Persona, M A; Alonso, A G

    1998-07-01

    The aim of this study was to evaluate the role of superoxide radicals in the healing of ischemic colonic anastomoses in the rat. Adult male Wistar rats were used in a factorial design with two factors (normal or ischemic colonic anastomoses) each having two levels (treatment with saline or allopurinol). Colonic anastomoses were performed either in normal or previously devascularized colons (ischemic anastomoses) at identical locations, using the same technique. On the fourth postoperative day, animals were killed, and specimens were taken for determinations. Ischemic anastomoses displayed significant increases in superoxide radical (assayed as superoxide anion), superoxide dismutase, and glutathione peroxidase concentrations. Bursting strength and hydroxyproline levels were also significantly lower in these anastomoses. Allopurinol administration elicited a significant decrease in superoxide anions and raised both bursting strength and hydroxyproline levels only in ischemic anastomoses. Superoxide radicals are involved in the delay in healing of ischemic anastomoses. Allopurinol lowers superoxide anion production and has beneficial effects on the cicatrization of ischemic anastomoses.

  11. Inhibitory effects of cardols and related compounds on superoxide anion generation by xanthine oxidase.

    Science.gov (United States)

    Masuoka, Noriyoshi; Nihei, Ken-ichi; Maeta, Ayami; Yamagiwa, Yoshiro; Kubo, Isao

    2015-01-01

    5-Pentadecatrienylresorcinol, isolated from cashew nuts and commonly known as cardol (C₁₅:₃), prevented the generation of superoxide radicals catalysed by xanthine oxidase without the inhibition of uric acid formation. The inhibition kinetics did not follow the Michelis-Menten equation, but instead followed the Hill equation. Cardol (C₁₀:₀) also inhibited superoxide anion generation, but resorcinol and cardol (C₅:₀) did not inhibit superoxide anion generation. The related compounds 3,5-dihydroxyphenyl alkanoates and alkyl 2,4-dihydroxybenzoates, had more than a C9 chain, cooperatively inhibited but alkyl 3,5-dihydroxybenzoates, regardless of their alkyl chain length, did not inhibit the superoxide anion generation. These results suggested that specific inhibitors for superoxide anion generation catalysed by xanthine oxidase consisted of an electron-rich resorcinol group and an alkyl chain having longer than C9 chain.

  12. Superoxide anion production by human neutrophils activated by Trichomonas vaginalis.

    Science.gov (United States)

    Song, Hyun-Ouk; Ryu, Jae-Sook

    2013-08-01

    Neutrophils are the predominant inflammatory cells found in vaginal discharges of patients infected with Trichomonas vaginalis. In this study, we examined superoxide anion (O2 (.-)) production by neutrophils activated by T. vaginalis. Human neutrophils produced superoxide anions when stimulated with either a lysate of T. vaginalis, its membrane component (MC), or excretory-secretory product (ESP). To assess the role of trichomonad protease in production of superoxide anions by neutrophils, T. vaginalis lysate, ESP, and MC were each pretreated with a protease inhibitor cocktail before incubation with neutrophils. Superoxide anion production was significantly decreased by this treatment. Trichomonad growth was inhibited by preincubation with supernatants of neutrophils incubated for 3 hr with T. vaginalis lysate. Furthermore, myeloperoxidase (MPO) production by neutrophils was stimulated by live trichomonads. These results indicate that the production of superoxide anions and MPO by neutrophils stimulated with T. vaginalis may be a part of defense mechanisms of neutrophils in trichomoniasis.

  13. Bosentan, a mixed endothelin receptor antagonist, inhibits superoxide anion-induced pain and inflammation in mice.

    Science.gov (United States)

    Serafim, Karla G G; Navarro, Suelen A; Zarpelon, Ana C; Pinho-Ribeiro, Felipe A; Fattori, Victor; Cunha, Thiago M; Alves-Filho, Jose C; Cunha, Fernando Q; Casagrande, Rubia; Verri, Waldiceu A

    2015-11-01

    Bosentan is a mixed endothelin receptor antagonist widely used to treat patients with pulmonary arterial hypertension, and the emerging literature suggests bosentan as a potent anti-inflammatory drug. Superoxide anion is produced in large amounts during inflammation, stimulates cytokine production, and thus contributes to inflammation and pain. However, it remains to be determined whether endothelin contributes to the inflammatory response triggered by the superoxide anion. The present study investigated the effects of bosentan in a mouse model of inflammation and pain induced by potassium superoxide, a superoxide anion donor. Male Swiss mice were treated with bosentan (10-100 mg/kg) by oral gavage, 1 h before potassium superoxide injection, and the inflammatory response was evaluated locally and at spinal cord (L4-L6) levels. Bosentan (100 mg/kg) inhibited superoxide anion-induced mechanical and thermal hyperalgesia, overt pain-like behavior (abdominal writhings, paw flinching, and licking), paw edema, myeloperoxidase activity (neutrophil marker) in the paw skin, and leukocyte recruitment in the peritoneal cavity. Bosentan also inhibited superoxide anion-induced interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) production, while it enhanced IL-10 production in the paw skin and spinal cord. Bosentan inhibited the reduction of antioxidant capacity (reduced glutathione, ferric reducing antioxidant power, and ABTS radical scavenging ability) induced by the superoxide anion. Finally, we demonstrated that intraplantar injection of potassium superoxide induces the mRNA expression of prepro-endothelin-1 in the paw skin and spinal cord. In conclusion, our results demonstrated that superoxide anion-induced inflammation, pain, cytokine production, and oxidative stress depend on endothelin; therefore, these responses are amenable to bosentan treatment.

  14. Mechanism and kinetics for scavenging superoxide anion by progesterone

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The chemical reaction of progesterone with superoxide anion in 0.1 mol/L NaHCO3 medium is studied by polarography. Differing from the indirect inhibition of generation by synthesized glucocorticoids in mechanism, the function that progesterone scavenges is ascribed to that directly oxidizes the C == C double bond conjugated with the carbonyl moiety of progesterone molecule to a free radical, and then is reduced to H2O2. The result obtained in this work gives new evidence for biomedical research. The equation of rate constant of the oxidization reaction is de-duced, and the apparent rate constant obtained is 308 L·mol-1·s-1.

  15. In vitro inhibition of superoxide anion production and superoxide dismutase activity by zinc in human spermatozoa.

    Science.gov (United States)

    Gavella, M; Lipovac, V; Vucić, M; Sverko, V

    1999-08-01

    The in vitro effect of zinc on superoxide anion (O2-) generation and on SOD-like activity in spermatozoa of infertile men was investigated. The formation of superoxide anion was stimulated by NADPH and the level of superoxide anion was measured by the reduction of ferricytochrome c. Both Percoll-isolated (n = 14) and washed spermatozoa (n = 14) exposed to 1 mmol/L zinc (60 min, 37 degrees C), released less (p zinc-untreated spermatozoa. These results implicate a possible role for zinc as a scavenger of excessive superoxide anions produced by defective spermatozoa in semen after ejaculation. Additionally, zinc was found to dose-dependently inhibit superoxide dismutase (SOD)-like activity of spermatozoa in vitro. The inhibition of SOD-like activity by an equal concentration of zinc (1 mmol/L) was less pronounced in oligospermic (p zinc to inhibit SOD-like activity may be relevant to the physiological function of spermatozoa in fertilization. The evidence that zinc may elicit an inhibition of both superoxide anion production and SOD-like activity in human spermatozoa, indicate the existence of novel, zinc-related mechanism(s) involved in the oxidative events occurring after ejaculation, with a possible modulatory effect on germ cell function.

  16. Antioxidative capacity and enzyme activity in Haematococcus pluvialis cells exposed to superoxide free radicals

    Institute of Scientific and Technical Information of China (English)

    刘建国; 张晓丽; 孙延红; 林伟

    2010-01-01

    The antioxidative capacity of astaxanthin and enzyme activity of reactive oxygen eliminating enzymes such as superoxide dismutase (SOD),peroxidase (POD),catalase (CAT) and ascorbate peroxidase (APX) were studied in three cell types of Haematococcus pluvialis exposed to high concentrations of a superoxide anion radical (O2ˉ).The results show that defensive enzymes and astaxanthin-related mechanisms were both active in H.pluvialis during exposure to reactive oxygen species (ROS) such as Oˉ2.Astaxanthin reacte...

  17. Scavenging of superoxide anions by lecithinized superoxide dismutase in HL-60 cells.

    Science.gov (United States)

    Ishihara, Tsutomu; Shibui, Misaki; Hoshi, Takaya; Mizushima, Tohru

    2016-01-01

    Superoxide dismutase covalently bound to four lecithin molecules (PC-SOD) has been found to have beneficial therapeutic effects in animal models of various diseases. However, the mechanism underlying these improved therapeutic effects has not yet been elucidated. It has previously been shown that PC-SOD localizes on the plasma membrane and in the lysosomes of cells. In this study, we evaluated the superoxide anion-scavenging activity of PC-SOD in HL-60 human promyelocytic leukemia cells. Compared to SOD, PC-SOD had only 17% scavenging activity in cell-free systems. Nevertheless, by analyzing enzyme activities in cell suspensions containing PC-SOD or SOD, PC-SOD and SOD showed almost equal activity for scavenging extracellular superoxide anions produced by HL-60 cells. Furthermore, the activity for scavenging extracellular superoxide anions increased with increased amount of PC-SOD on the plasma membrane. Moreover, PC-SOD exhibited no obvious inhibitory effect on the scavenging of intracellular superoxide anions. These results suggested that the association of PC-SOD with the plasma membrane plays a key role in its beneficial therapeutic effects. Thus, this finding may provide a rationale for selecting target diseases for PC-SOD treatment.

  18. Superoxide anion production and superoxide dismutase and catalase activities in Coxiella burnetii.

    OpenAIRE

    Akporiaye, E T; Baca, O G

    1983-01-01

    Coxiella burnetii was examined for superoxide anion (O2-) production and superoxide dismutase and catalase activities. The organism generated O2- at pH 4.5 but not at pH 7.4. The rickettsia displayed superoxide dismutase activity distinguishable from that of the host cell (L-929 mouse fibroblast). Catalase activity was maximal at pH 7.0 and diminished at pH 4.5. These enzymes may account, in part, for the ability of this obligate intracellular parasite to survive within phagocytes.

  19. A novel murrel Channa striatus mitochondrial manganese superoxide dismutase: gene silencing, SOD activity, superoxide anion production and expression.

    Science.gov (United States)

    Arockiaraj, Jesu; Palanisamy, Rajesh; Bhatt, Prasanth; Kumaresan, Venkatesh; Gnanam, Annie J; Pasupuleti, Mukesh; Kasi, Marimuthu

    2014-12-01

    We have reported the molecular characterization including gene silencing, superoxide activity, superoxide anion production, gene expression and molecular characterization of a mitochondrial manganese superoxide dismutase (mMnSOD) from striped murrel Channa striatus (named as CsmMnSOD). The CsmMnSOD polypeptide contains 225 amino acids with a molecular weight of 25 kDa and a theoretical isoelectric point of 8.3. In the N-terminal region, CsmMnSOD carries a mitochondrial targeting sequence and a superoxide dismutases (SOD) Fe domain (28-109), and in C-terminal region, it carries another SOD Fe domain (114-220). The CsmMnSOD protein sequence shared significant similarity with its homolog of MnSOD from rock bream Oplegnathus fasciatus (96%). The phylogenetic analysis showed that the CsmMnSOD fell in the clade of fish mMnSOD group. The monomeric structure of CsmMnSOD possesses 9 α-helices (52.4%), 3 β-sheets (8.8%) and 38.8% random coils. The highest gene expression was noticed in liver, and its expression was inducted with fungal (Aphanomyces invadans) and bacterial (Aeromonas hydrophila) infections. The gene silencing results show that the fish that received dsRNA exhibited significant (P superoxide anion production was determined by calculating the granular blood cell count during infection in murrel. It shows that the infection influenced the superoxide radical production which plays a major role in killing the pathogens. Overall, this study indicated the defense potentiality of CsmMnSOD; however, further research is necessary to explore its capability at protein level.

  20. Carbon dioxide suppresses macrophage superoxide anion production independent of extracellular pH and mitochondrial activity

    NARCIS (Netherlands)

    Kuebler, Joachim F.; Kos, Marcin; Jesch, NataLie K.; Metzelder, Martin L.; van der Zee, David C.; Bax, Klaas M.; Vieten, Gertrud; Ure, Benno M.

    2007-01-01

    Background: Superoxide anions released by activated inacrophages during surgery are considered to be responsible for local cellular damage. Application of CO2 prieumoperitoneum during laparoscopy affects superoxide anion release, but the underlying mechanism remains unclear and the data reported are

  1. Nanostructured cobalt phosphates as excellent biomimetic enzymes to sensitively detect superoxide anions released from living cells.

    Science.gov (United States)

    Wang, Min-Qiang; Ye, Cui; Bao, Shu-Juan; Xu, Mao-Wen; Zhang, Yan; Wang, Ling; Ma, Xiao-Qing; Guo, Jun; Li, Chang-Ming

    2017-01-15

    Monitoring superoxide anion radicals in living cells has been attracting much academic and industrial interest due to the dual roles of the radicals. Herein, we synthesized a novel nanostructured cobalt phosphate nanorods (Co3(PO4)2 NRs) with tunable pore structure using a simple and effective micro-emulsion method and explored their potential utilization in the electrochemical sensing of superoxide anions. As an analytical and sensing platform, the nanoscale biomimetic enzymes Co3(PO4)2 NRs exhibited excellent selectivity and sensitivity towards superoxide anion (O2(•-)) with a low detection limit (2.25nM), wide linear range (5.76-5396nM), and long-term stability. Further, the nanoscale biomimetic enzyme could be efficiently applied in situ to electrochemically detect O2(•-) released from human malignant melanoma cells and normal keratinocyte, showing excellent real time quantitative detection capability. This material open up exciting opportunities for implementing biomimetic enzymes in nanoscale transition metal phosphates and designing enzyme-free biosensors with much higher sensitivity and durability in health and disease analysis than those of natural one.

  2. Equine digital veins are more sensitive to superoxide anions than digital arteries.

    Science.gov (United States)

    Lapo, Rock Allister; Gogny, Marc; Chatagnon, Gérard; Lalanne, Valérie; Harfoush, Khaled; Assane, Moussa; Desfontis, Jean-Claude; Mallem, Mohamed Yassine

    2014-10-05

    This work was designed to investigate (i) the effect of superoxide dismutase (SOD) inhibition on endothelial function and (ii) the free radical-induced endothelial dysfunction in equine digital veins (EDVs) and equine digital arteries (EDAs) isolated from healthy horses. EDV and EDA rings were suspended in a 5 ml organ bath containing Krebs solution. After a 60 min equilibration period, EDV and EDA rings were contracted with phenylephrine. Then, cumulative concentration-response curves (CCRCs) to acetylcholine were performed. In both EDVs and EDAs, acetylcholine (1 nM to 10 µM) produced concentration-dependent relaxation. We investigated the influence of SOD inhibition by diethyldithiocarbamate (DETC; 100 µM), a CuZnSOD inhibitor, on EDAs and EDVs relaxant responses to acetylcholine. Acetylcholine -mediated relaxation was impaired by DETC only in EDVs. SOD activity assayed by a xanthine-xanthine oxidase method was higher in EDAs compared with EDVs (Psuperoxide anions generating systems showed that in both EDVs and EDAs, the acetylcholine-mediated relaxation was significantly impaired by pyrogallol and homocysteine. This impairment was more pronounced in EDVs than in EDAs. Moreover, the pyrogallol-induced impairment of acetylcholine-mediated relaxation was potentiated by DETC to a greater extent in EDVs. We concluded that due to the lower activity of SOD, EDVs are more sensitive to superoxide anions than EDAs. So, any alteration of superoxide anions metabolism is likely to have a more important impact on venous rather than arterial relaxation.

  3. Traditional Chinese medicine formula Qing Huo Yi Hao as superoxide anion scavenger in high glucosetreated endothelial cells

    Institute of Scientific and Technical Information of China (English)

    Qiong xu; Bin ZHANG; Xiao-mu LI; Xin GAO

    2012-01-01

    Aim:To investigate the effects of a traditional Chinese medicine formula Qing Huo Yi Hao (QHYH)and its components on hydroxyl radical (HO·)production in vitro and the activity of QHYH against free radicals in cultured endothelial cells induced by high glucose.Methods:Hydroxyl radicals (HO·)were generated through Fenton reactions in vitro,and 5,5-dimethyl-1-pyrroline N-oxide (DMPO)was used as a spin trap to form DMPO/HO·adducts detected using electron paramagnetic resonance (EPR).Immortalized mouse cerebral microvascular endothelial (bEnd.3)cells were treated with high glucose (35 mmol/L).The free radical scavenging ability of QHYH in the cells was evaluated using EPR.Superoxide dismutase (SOD)was used to identify the free radicals scavenged by QHYH in the cells.Results:QHYH and its 8 components concentration-dependently reduced DMPO/HO· signaling.The DMPO/HO· adduct scavenging ability of QHYH was 82.2%,which was higher than each individual component.The free radical scavenging ability of 1% QHYH in high glucose-treated bEnd.3 cells was approximately 70%.In these cells,the free radicals were also specifically reduced by SOD (400 U/mL),implying that the free radicals were primarily superoxide anions.Conclusion:The results demonstrate that the QHYH formula is potent antioxidant acting as scavenge of superoxide anions in high glucose-treated endothelial cells.

  4. Superoxide anion-induced pain and inflammation depends on TNFα/TNFR1 signaling in mice.

    Science.gov (United States)

    Yamacita-Borin, Fabiane Y; Zarpelon, Ana C; Pinho-Ribeiro, Felipe A; Fattori, Victor; Alves-Filho, Jose C; Cunha, Fernando Q; Cunha, Thiago M; Casagrande, Rubia; Verri, Waldiceu A

    2015-09-25

    Inhibition of tumor necrosis factor-alpha (TNFα) and superoxide anion production reduces inflammation and pain. The present study investigated whether superoxide anion-induced pain depends on TNFα signaling and the role of superoxide anion in TNFα-induced hyperalgesia to clarify the interrelation between these two mediators in the context of pain. Intraplantar injection of a superoxide anion donor (potassium superoxide) induced mechanical hyperalgesia (0.5-5h after injection), neutrophil recruitment (myeloperoxidase activity), and overt pain-like behaviors (paw flinching, paw licking, and abdominal writhings) in wild-type mice. Tumor necrosis factor receptor 1 deficiency (TNFR1-/-) and treatment of wild-type mice with etanercept (a soluble TNFR2 receptor that inhibits TNFα actions) inhibited superoxide anion-induced pain-like behaviors. TNFR1(-/-) mice were also protected from superoxide anion donor-induced oxidative stress, suggesting the role of this pathway in the maintenance of oxidative stress. Finally, we demonstrated that Apocynin (an NADPH oxidase inhibitor) or Tempol (a superoxide dismutase mimetic) treatment inhibited TNFα-induced paw mechanical hyperalgesia and neutrophil recruitment (myeloperoxidase activity). These results demonstrate that TNFα/TNFR1 signaling is important in superoxide anion-triggered pain and that TNFα/TNFR1 signaling amplifies the oxidative stress triggered by superoxide anion, which contributes to sustaining pain and inflammation.

  5. (Bi)sulfite Oxidation by Copper,Zinc-Superoxide Dismutase: Sulfite-Derived, Radical-Initiated Protein Radical Formation

    Science.gov (United States)

    Ranguelova, Kalina; Bonini, Marcelo G.; Mason, Ronald P.

    2010-01-01

    Background Sulfur dioxide, formed during the combustion of fossil fuels, is a major air pollutant near large cities. Its two ionized forms in aqueous solution, sulfite and (bi)sulfite, are widely used as preservatives and antioxidants to prevent food and beverage spoilage. (Bi)sulfite can be oxidized by peroxidases to form the very reactive sulfur trioxide anion radical (•SO3−). This free radical further reacts with oxygen to form the peroxymonosulfate anion radical (−O3SOO•) and sulfate anion radical (SO4• −). Objective To explore the critical role of these radical intermediates in further oxidizing biomolecules, we examined the ability of copper,zinc-superoxide dismutase (Cu,Zn-SOD) to initiate this radical chain reaction, using human serum albumin (HSA) as a model target. Methods We used electron paramagnetic resonance, optical spectroscopy, oxygen uptake, and immuno-spin trapping to study the protein oxidations driven by sulfite-derived radicals. Results We found that when Cu,Zn-SOD reacted with (bi)sulfite, •SO3− was produced, with the concomitant reduction of SOD-Cu(II) to SOD-Cu(I). Further, we demonstrated that sulfite oxidation mediated by Cu,Zn-SOD induced the formation of radical-derived 5,5-dimethyl-1-pyrroline N-oxide (DMPO) spin-trapped HSA radicals. Conclusions The present study suggests that protein oxidative damage resulting from (bi)sulfite oxidation promoted by Cu,Zn-SOD could be involved in oxidative damage and tissue injury in (bi)sulfite-exacerbated allergic reactions. PMID:20348042

  6. 酶法制备鲽鱼鱼皮胶原蛋白肽及其清除超氧阴离子自由基的研究%Study on the Enzymatic Preparation and Superoxide Anion Radical Scavenging Activity of Collagen Peptide from Plaice Skin

    Institute of Scientific and Technical Information of China (English)

    王群; 郑海涛; 葛尧; 何计国

    2011-01-01

    采用碱性蛋白酶酶解鲽鱼鱼皮胶原蛋白制备胶原蛋白肽,对其清除超氧阴离子自由基的能力进行研究.通过单因素试验和响应面法分析不同酶解条件对超氧阴离子自由基清除率的影响,优化得到最佳酶解工艺条件:pH 9.5,加酶量158l U/g,底物浓度10 mg/mL,酶解时间为6h,酶解温度60℃,最高清除率为75.51%,半数清除浓度(IC5o)为7.98 mg/mL.%Alcalase was used to hydrolyze plaice skin for preparing collagen peptide, and the superoxide anion radical scavenging activity of this collagen peptide was studied. Effect of the different enzymatic hydrolysis conditions on superoxide anion radical scavenging activity were analyzed by single factor experiment and response surface method. The optimal hydrolytic conditions of plaice skin collagen using Alcalase with high scavenging rate were pH=9.5, enzyme dosage 1581 U/g, concentration of substrate 10 mg/mL, hydrolysis time 6 h, temperature 60℃. The maximum scavenging rate of 75.51% and half scavenging concentration (IC50) of 7.98 mg/mL were obtained.

  7. Bleaching of the red anthocyanin induced by superoxide radical.

    Science.gov (United States)

    Yamasaki, H; Uefuji, H; Sakihama, Y

    1996-08-01

    Red anthocyanin prepared from petals of Hibiscus rosa-sinensis L. was photobleached in the EDTA-riboflavin system. The rate of bleaching monitored at 565 nm depended on the light intensity and EDTA concentrations. Anaerobic conditions and/or addition of superoxide dismutase prevented the bleaching of anthocyanin, whereas mannitol and catalase did not. A similar bleaching was observed under dark conditions in the xanthine-xanthine oxidase system. The results indicate that anthocyanin is bleached by the nonenzymatic reaction with the superoxide radical and suggest that the pigment can function as an antioxidant. The antioxidative efficiency of cyanidin to superoxide was 10-fold higher than that of cyanidin-3-sophoroside as a Hibiscus anthocyanin.

  8. Anion photoelectron spectroscopy of radicals and clusters

    Energy Technology Data Exchange (ETDEWEB)

    Travis, Taylor R. [Univ. of California, Berkeley, CA (United States)

    1999-12-01

    Anion photoelectron spectroscopy is used to study free radicals and clusters. The low-lying 2Σ and 2π states of C2nH (n = 1--4) have been studied. The anion photoelectron spectra yielded electron affinities, term values, and vibrational frequencies for these combustion and astrophysically relevant species. Photoelectron angular distributions allowed the author to correctly assign the electronic symmetry of the ground and first excited states and to assess the degree of vibronic coupling in C2H and C4H. Other radicals studied include NCN and I3. The author was able to observe the low-lying singlet and triplet states of NCN for the first time. Measurement of the electron affinity of I3 revealed that it has a bound ground state and attachment of an argon atom to this moiety enabled him to resolve the symmetric stretching progression.

  9. Superoxide anion production by neutrophils in myelodysplastic syndromes (preleukemia.

    Directory of Open Access Journals (Sweden)

    Takahashi,Isao

    1988-02-01

    Full Text Available Superoxide anion (O2- production by neutrophils from 14 untreated patients with acute nonlymphocytic leukemia (ANLL was significantly less than that of healthy controls (4.93 +/- 1.99 vx 6.20 +/- 1.53 nmol/min/10(6 neutrophils, p less than 0.05. In 10 patients with myelodysplastic syndrome (MDS, however, it was not significantly different from the control level although 6 of the 10 patients had low levels, when individual patients were compared with the lower limit of the control range. An inverse correlation between the O2- production of neutrophils and the percentage of leukemic cells in the marrow existed in ANLL (r = -0.55, p less than 0.01, but not in MDS. Three of 4 MDS patients who died of pneumonia prior to leukemic conversion showed a low level of O2- production. The impaired O2- production by neutrophils from some MDS patients, probably due to the faulty differentiation from leukemic clones, may be one of the causes of enhanced susceptibility to infection.

  10. Endomorphins 1 and 2 modulate chemotaxis, phagocytosis and superoxide anion production by microglia.

    Science.gov (United States)

    Azuma, Y; Ohura, K; Wang, P L; Shinohara, M

    2001-09-03

    We evaluate the role of endomorphins 1 and 2 on microglial functions. Endomorphins 1 and 2 blocked phagocytosis of Escherichia coli. In addition, both markedly inhibited chemotaxis toward zymosan-activated serum. In contrast, when microglia was preincubated with these endomorphins, followed by incubation with LPS before stimulation with phorbol 12-myristate 13-acetate (PMA) at 200 nM, they potentiated superoxide anion production. Furthermore, when microglia was preincubated with these endomorphins together with PMA at 20 nM, followed by stimulation with PMA at 200 nM, superoxide anion production was potentiated. These results suggest that endomorphins 1 and 2 modulate phagocytosis, chemotaxis and superoxide anion production by microglia.

  11. Superoxide Radical Formation in Isolated PMN from Experimental Vaginal Trichomoniasis

    Directory of Open Access Journals (Sweden)

    Z Valadkhani

    2006-06-01

    Full Text Available Trichomoniasis, the most widespread sexually transmitted disease is caused by Trichomonas vaginalis. This parasite is site specific for the genitourinary tract and recruitment of macrophages as well as polymorphonuclear nutrophils (PMN to the site of infection is the first line of defense as a component of non-specific resistance and immunity. In this study, BALB/c mice were infected with 10 isolates from symptomatic and 10 from asymptomatic patients. Then PMN from vaginal washes, vaginal tissue and blood of infected mice was isolated and the rate of superoxide formation by intact stimulated PMN was measured. Results showed that, mice infected with symptomatic isolates indicated significant increase in polymorphs with increase in days of infection as compared with mice infected with asymptomatic isolate and control (uninfected animals. Vaginal tissue cells generated maximal amount of superoxide in symptomatic isolates infected animals (5.17 ± 0.36 as compared to asymptomatic isolates (4.54 ± 0.43, which brings out the maximal abnormality in PMN in this localized area. The amount of superoxide radicals generated by cells of vaginal washes and blood of symptomatic isolate infected mice 4.29 ± 0.25 and 2.16 ± 0.35 was less than the asymptomatic isolate (4.94 ± 0.49 and 3.18 ± 0.26, respectively. This study indicates that super oxide radical generation may play role in establishing the infection.

  12. Induction of Apoptosis by Superoxide Anion and the Protective Effects of Selenium and Vitamin E

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Objective The purpose of this study is to investigate the effect of superoxide anion on the apoptosis of cultured fibroblasts and the protective role of selenium and Vitamin E. Methods Cultured fibroblasts (NIH3T3), with or without selenium or vitamin E in the medium, were treated by superoxide anion produced by xanthine/xanthine oxidase reaction system and changes in cell structure and DNA were observed microscopically and electrophoretically. Results Apoptosis was observed when superoxide anion at a concentration of 5 nmol/L or 10 nmol/L had acted on the fibroblasts for 5-10 h. Selenium and Vitamin E in the medium inhibited the apoptosis significantly when their concentrations reached 1.15 mol/L and 2.3 mol/L respectively. Conclusion Selenium and vitamin E have protective effect against the apoptosis induced by superoxide anion. The effect of selenium is more remarkable than that of vitamin E.

  13. Chemiluminescence Imaging of Superoxide Anion Detects Beta-Cell Function and Mass.

    Science.gov (United States)

    Bronsart, Laura L; Stokes, Christian; Contag, Christopher H

    2016-01-01

    Superoxide anion is produced during normal cellular respiration and plays key roles in cellular physiology with its dysregulation being associated with a variety of diseases. Superoxide anion is a short-lived molecule and, therefore, its homeostatic regulation and role in biology and disease requires dynamic quantification with fine temporal resolution. Here we validated coelenterazine as a reporter of intracellular superoxide anion concentration and used it as a dynamic measure both in vitro and in vivo. Chemiluminescence was dependent upon superoxide anion levels, including those produced during cellular respiration, and concentrations varied both kinetically and temporally in response to physiologically relevant fluctuations in glucose levels. In vivo imaging with coelenterazine revealed that beta cells of the pancreas have increased levels of superoxide anion, which acted as a measure of beta-cell function and mass and could predict the susceptibility of mice to diabetes mellitus. Glucose response and regulation are key elements of cellular physiology and organismal biology, and superoxide anion appears to play a fundamental and dynamic role in both of these processes.

  14. Anamperometric superoxide anion radicalbiosensor based on SOD/PtPd-PDARGO modified electrode.

    Science.gov (United States)

    Tang, Jie; Zhu, Xiang; Niu, Xiangheng; Liu, Tingting; Zhao, Hongli; Lan, Minbo

    2015-05-01

    In the present work, a high-performance enzyme-based electrochemical sensor for the detection of superoxide anion radical (O2(●-)) is reported. Firstly, we employed a facile approach to synthesize PtPd nanoparticles (PtPd NPs) on chemically reduced graphene oxide (RGO) coated with polydopamine (PDA). The prepared PtPd-PDARGO composite was well characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectra, X-ray diffraction, X-ray photoelectron spectroscopy and electrochemical methods. Then the assembled composite was used as a desired electrochemcial interface for superoxide dismutase (SOD) immobilization. Owing to the PDA layer as well as the synergistic effect of PtPd NPs, the fabricated SOD/PtPd-PDARGO sensor exhibited an outstanding sensitivity of 909.7 μA mM(-1) cm(-2) upon O2(●-) in a linear range from 0.016 mM to 0.24 mM (R(2)=0.992), with a low detection limit of 2 μM (S/N=3) and excellent selectivity, good reproducibility as well as favorable long-term stability.

  15. Iron-mediated induction of sister-chromatid exchanges by hydrogen peroxide and superoxide anion.

    Science.gov (United States)

    Larramendy, M; Mello-Filho, A C; Martins, E A; Meneghini, R

    1987-05-01

    When Chinese hamster fibroblasts were exposed to hydrogen peroxide or to a system consisting of xanthine oxidase and hypoxanthine, which generates superoxide anion plus hydrogen peroxide, sister-chromatid exchanges (SCEs) were formed in a dose-dependent manner. When the iron-complexing agent o-phenanthroline was present in the medium, however, the production of these SCEs was completely inhibited. This fact indicates that the Fenton reaction: Fe2+ + H2O2----OH0 + OH- + Fe3+ is responsible for the production of SCEs. When O2- and H2O2 were generated inside the cell by incubation with menadione, the production of SCE was prevented by co-incubation with copper diisopropylsalicylate, a superoxide dismutase mimetic agent. The most likely role of O2- is as a reducing agent of Fe3+: O2- + Fe3+----Fe2+ + O2, so that the sum of this and the Fenton reaction, i.e., the iron-catalyzed Haber-Weiss reaction, provides an explanation for the active oxygen species-induced SCE: H2O2 + O2(-)----OH- + OH0 + O2. According to this view, the OH radical thus produced is the agent which ultimately causes SCE. These results are discussed in comparison with other mechanisms previously proposed for induction of SCE by active oxygen species.

  16. Correlation between the circadian rhythm of melatonin, phagocytosis, and superoxide anion levels in ring dove heterophils.

    Science.gov (United States)

    Rodríguez, A B; Marchena, J M; Nogales, G; Durán, J; Barriga, C

    1999-01-01

    A functional role for melatonin is its relationship to circadian timing mechanisms. In addition, there has recently been assumed to be a functional connection between the pineal gland and the immune system in mammals and birds, with some findings showing melatonin to be a free radical scavenger and general antioxidant. The present study investigates the possible relationship between the circadian rhythm of melatonin and the ingestion capacity as well as superoxide anion levels of ring dove (Streptopelia risoria) heterophils. In birds, heterophils, with their ability to ingest and kill different antigens, play a central role in the host defence mechanism. All determinations were made during 24 hr periods at 2 hr intervals. Radioimmunoassay showed an increase of melatonin serum levels during the dark period (from 20:00 to 07:00 hr) with a maximum at 04:00 hr, and a significant decline during the hours of light with a minimum at 16:00 hr. Similarly, the phagocytic index was enhanced during the night, with the maximum at approximately 04:00 hr and the minimum at approximately 18:00 hr. The same was the case in relation to phagocytic percentage. However, the superoxide anion levels were lower during darkness (minimum at 04:00 hr) and higher during the light period (maximum at 14:00 hr). In conclusion, our findings show that one pineal-mediated effect on the immune system may be a direct action of melatonin on phagocytosis and the phagocytic biochemical process, and that this neurohormone might act as an antioxidant.

  17. Quantification of superoxide radical production in thylakoid membrane using cyclic hydroxylamines.

    Science.gov (United States)

    Kozuleva, Marina; Klenina, Irina; Mysin, Ivan; Kirilyuk, Igor; Opanasenko, Vera; Proskuryakov, Ivan; Ivanov, Boris

    2015-12-01

    Applicability of two lipophilic cyclic hydroxylamines (CHAs), CM-H and TMT-H, and two hydrophilic CHAs, CAT1-H and DCP-H, for detection of superoxide anion radical (O2(∙-)) produced by the thylakoid photosynthetic electron transfer chain (PETC) of higher plants under illumination has been studied. ESR spectrometry was applied for detection of the nitroxide radical originating due to CHAs oxidation by O2(∙-). CHAs and corresponding nitroxide radicals were shown to be involved in side reactions with PETC which could cause miscalculation of O2(∙-) production rate. Lipophilic CM-H was oxidized by PETC components, reducing the oxidized donor of Photosystem I, P700(+), while at the same concentration another lipophilic CHA, TMT-H, did not reduce P700(+). The nitroxide radical was able to accept electrons from components of the photosynthetic chain. Electrostatic interaction of stable cation CAT1-H with the membrane surface was suggested. Water-soluble superoxide dismutase (SOD) was added in order to suppress the reaction of CHA with O2(∙-) outside the membrane. SOD almost completely inhibited light-induced accumulation of DCP(∙), nitroxide radical derivative of hydrophilic DCP-H, in contrast to TMT(∙) accumulation. Based on the results showing that change in the thylakoid lumen pH and volume had minor effect on TMT(∙) accumulation, the reaction of TMT-H with O2(∙-) in the lumen was excluded. Addition of TMT-H to thylakoid suspension in the presence of SOD resulted in the increase in light-induced O2 uptake rate, that argued in favor of TMT-H ability to detect O2(∙-) produced within the membrane core. Thus, hydrophilic DCP-H and lipophilic TMT-H were shown to be usable for detection of O2(∙-) produced outside and within thylakoid membranes.

  18. Protonation Reaction of Benzonitrile Radical Anion and Absorption of Product

    DEFF Research Database (Denmark)

    Holcman, Jerzy; Sehested, Knud

    1975-01-01

    The rate constant for the protonation of benzonitrile radical anions formed in pulse radiolysis of aqueous benzonitrile solutions is (3.5 ± 0.5)× 1010 dm3 mol–1 s–1. A new 270 nm absorption band is attributed to the protonated benzonitrile anion. The pK of the protonation reaction is determined...

  19. Superoxide radicals can act synergistically with hypochlorite to induce damage to proteins

    DEFF Research Database (Denmark)

    Hawkins, Clare Louise; Rees, Martin D; Davies, Michael Jonathan

    2002-01-01

    Activated phagocytes generate both superoxide radicals via a respiratory burst, and HOCl via the concurrent release of the haem enzyme myeloperoxidase. Amine and amide functions on proteins and carbohydrates are major targets for HOCl, generating chloramines (RNHCl) and chloramides (RC(O)NClR'), ......Activated phagocytes generate both superoxide radicals via a respiratory burst, and HOCl via the concurrent release of the haem enzyme myeloperoxidase. Amine and amide functions on proteins and carbohydrates are major targets for HOCl, generating chloramines (RNHCl) and chloramides (RC......(O)NClR'), which can accumulate to high concentrations (>100 microM). Here we show that superoxide radicals catalyse the decomposition of chloramines and chloramides to reactive nitrogen-centred radicals, and increase the extent of protein fragmentation compared to that observed with either superoxide radicals...... or HOCl, alone. This synergistic action may be of significance at sites of inflammation, where both superoxide radicals and chloramines/chloramides are formed simultaneously....

  20. Role of superoxide dismutase enzymes and ascorbate in protection of nitrergic relaxation against superoxide anions in mouse duodenum

    Institute of Scientific and Technical Information of China (English)

    M Ata SECILMIS; Olcay Ergurhan KIROGLU; Nuran OGULENER

    2008-01-01

    Aim: The aim of this study was to investigate whether superoxide dismutase (SOD) enzymes and ascorbate play a role in the protection of the nitrergic relax-ation against superoxide anion inhibition in the mouse duodenum. Methods: The effects of exogenous SOD, N,N'-bis(salicylidene) ethylenediamine chlo-ride (EUK-8; a synthetic cell-permeable mimetic of the manganese SOD [Mn SOD] and ascorbate on relaxant responses induced by nitrergic nerve stimulation), exogenous nitric oxide (NO), and nitroglycerin were investigated in isolated mouse duodenum tissues. Results: Diethyidithiocarbamate (DETCA) inhibited the relaxation to exogenous NO and nitroglycerin, but not relaxation to electri-cal field stimulation (EFS). SOD and ascorbate partially prevented the inhibi-tory effect of DETCA on relaxation to NO, abut not to nitroglycerin. The DETCA-induced inhibition on nitroglycerin was prevented by ELrK-8. Hemoglobin, 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazolinel-oxyl-3-oxide, and hydroxo-cobalamin inhibited the relaxation to NO, but not to EFS and nitroglycerin in the presence of DETCA. Pyrogallol and hydroquinone inhibited the relaxation to NO, but not to EFS and nitroglycerin. This inhibition was prevented by exog-enous SOD and ascorbate, but was not prevented by EUK-8. Pyrogallol and hy-droquinone did not inhibit the EFS-induced relaxation in the presence of DETCA. Duroquinone and 6-anilino-5.8-quinolinedione inhibited the relaxation to EFS, NO, and nitroglycerin, and this inhibition was prevented by EUK-8. Conclusion: These results suggest that the nitrergic neurotransmission in the mouse duode-num is protected by endogenous tissue antioxidants against superoxide anions, and Mn SOD, in addition to copper/zinc SOD, can protect NO from attack from superoxide anion generators intracellularly. Also, the possibility that the endog-enous neurotransmitter may not be the free NO but a NO-containing or NO-generating molecule in the mouse duodenum remains open.

  1. Effect of superoxide anion scavenger on rat hearts with chronic intermittent hypoxia.

    Science.gov (United States)

    Pai, Peiying; Lai, Ching Jung; Lin, Ching-Yuang; Liou, Yi-Fan; Huang, Chih-Yang; Lee, Shin-Da

    2016-04-15

    Only very limited information regarding the protective effects of the superoxide anion scavenger on chronic intermittent hypoxia-induced cardiac apoptosis is available. The purpose of this study is to evaluate the effects of the superoxide anion scavenger on cardiac apoptotic and prosurvival pathways in rats with sleep apnea. Forty-two Sprague-Dawley rats were divided into three groups, rats with normoxic exposure (Control, 21% O2, 1 mo), rats with chronic intermittent hypoxia exposure (Hypoxia, 3-7% O2vs. 21% O2per 40 s cycle, 8 h per day, 1 mo), and rats with pretreatment of the superoxide anion scavenger and chronic intermittent hypoxia exposure (Hypoxia-O2 (-)-Scavenger, MnTMPyP pentachloride, 1 mg/kg ip per day; 3-7% O2vs. 21% O2per 40 s cycle, 8 h per day, 1 mo) at 5-6 mo of age. After 1 mo, the protein levels and apoptotic cells of excised hearts from three groups were measured by Western blotting and terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL) assay. The superoxide anion scavenger decreased hypoxia-induced myocardial architecture abnormalities, left ventricular hypertrophy, and TUNEL-positive apoptosis. The superoxide anion scavenger decreased hypoxia-induced Fas ligand, Fas death receptors, Fas-associated death domain (FADD), activated caspase-8, and activated caspase-3 (Fas-dependent apoptotic pathway) as well as Bad, activated caspase-9 and activated caspase-3 (mitochondria-dependent apoptotic pathway), endonuclease G (EndoG), apoptosis-inducing factor (AIF), and TUNEL-positive apoptosis. The superoxide anion scavenger increased IGF-1, IGF-1R, p-PI3k, p-Akt, p-Bad, Bcl-2, and Bcl-xL (survival pathway). Our findings imply that the superoxide anion scavenger might prevent cardiac Fas-mediated and mitochondrial-mediated apoptosis and enhance the IGF-1-related survival pathway in chronic intermittent hypoxia. The superoxide anion scavenger may prevent chronic sleep apnea-enhanced cardiac apoptotic pathways and enhances

  2. Superoxide dismutase activity of the naturally occurring human serum albumin-copper complex without hydroxyl radical formation.

    Science.gov (United States)

    Kato, Ryunosuke; Akiyama, Matofusa; Kawakami, Hiroyoshi; Komatsu, Teruyuki

    2014-01-01

    The superoxide radical anion (O2(.-)) is biologically toxic and contributes to the pathogenesis of various diseases. Here we describe the superoxide dismutase (SOD) activity of human serum albumin (HSA) complexed with a single Cu(II) ion at the N-terminal end (HSA-Cu complex). The structure of this naturally occurring copper-coordinated blood serum protein has been characterized by several physicochemical measurements. The O2(.-) dismutation ability of the HSA-Cu (1:1) complex is almost the same as that of the well-known SOD mimics, such as Mn(III) -tetrakis(N-methylpyridinium)porphyrin. Interestingly, the HSA-Cu complex does not induce a subsequent Fenton reaction to produce the hydroxyl radical (OH(.)), which is one of the most harmful reactive oxygen species.

  3. Induction of Apoptosis by Superoxide Anion and the Protective Effects of Selenium and Vitamin E

    Institute of Scientific and Technical Information of China (English)

    GUOLING; XUEAN-NA; 等

    2001-01-01

    Objective:The purpose of this study is to investigate the effect of superoxide anion on the apoptosis of cultured fibroblasts and the protective role of seleium and Vitamin E.Methods:Cultured fibroblasts(NIH3T3),with or without selenium or vitamin E in the medium,were treated by superoxide anion produced by xanthine/xanthine oxidase reaction system and changes in cell structure and DNA were observed microscopically and electrophoretically,Results:Apoptosis was observed when superoxide anion at a concentration of 5nmol/L or 10nmol/L had acted on the fibroblasts for 5-10h.Selenium and Vitamin E in the medium inhibited the apoptosis significantly when their concentrations reached 1.15mol/L and 2.3mol/L respectively.Concleusion:selenium and vitamin Ehave protective effect against the apoptosis induced by superoxide anion.The effect of selenium is more remakable than that of vitamin E.

  4. Osmotic stress stimulates generation of superoxide anion by spermatozoa in horses.

    Science.gov (United States)

    Burnaugh, L; Ball, B A; Sabeur, K; Thomas, A D; Meyers, S A

    2010-02-01

    The objective of this study was to examine the interplay between osmotic and oxidative stress as well as to determine mechanisms by which osmotic stress increases superoxide generation in spermatozoa of horses. Superoxide production, as measured by dihydroethidium (DHE), increased when spermatozoa of horses were incubated under either hyperosmotic or hyposmotic conditions. This increase in superoxide production was inhibited by the MAP kinase p38 inhibitor, SB203580, and by the superoxide scavenger, tiron. Incubation of spermatozoa under hyperosmotic conditions increased overall protein tyrosine phosphorylation as measured by western blotting techniques; however, a similar increase was not detected when spermatozoa were incubated under hyposmotic conditions. The general protein kinase C (PKC) and protein tyrosine kinase (PTK) inhibitor staurosporine inhibited (P<0.05) tyrosine phosphorylation in samples from cells under hyperosmotic conditions. In addition, the NADPH oxidase inhibitor diphenyleneiodonium (DPI) also inhibited (P<0.05) protein tyrosine phosphorylation in cells under hyperosmotic conditions. In summary, these data indicate that incubation of equine spermatozoa under both hyposmotic and hyperosmotic conditions can increase superoxide anion generation. Under hyperosmotic conditions, this increased generation of superoxide anion was accompanied by increased protein tyrosine phosphorylation.

  5. Isoprene, sulphoxy radical-anions and acidity

    Science.gov (United States)

    Rudziński, 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.

  6. Isoprene, sulphoxy radical-anions and acidity

    Directory of Open Access Journals (Sweden)

    K. J. Rudziński

    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.

  7. Formation and cleavage of aromatic disulfide radical anions.

    Science.gov (United States)

    Antonello, Sabrina; Daasbjerg, Kim; Jensen, Henrik; Taddei, Ferdinando; Maran, Flavio

    2003-12-03

    The electron transfer (ET) to a series of para-substituted diaryl disulfides, having the general formula (X-C(6)H(4)S-)(2), has been studied. The X groups were selected as to have a comprehensive variation of the substituent effect, being X = NH(2), MeO, H, F, Cl, CO(2)Et, CN, and NO(2). The reduction was carried out experimentally, using N,N-dimethylformamide as the solvent, and by molecular orbital (MO) ab initio calculations. The ET was studied heterogeneously, by voltammetric reduction and convolution analysis, and homogeneously, by using electrogenerated radical anions as the solution electron donors. The reduction is dissociative, leading to the cleavage of the S-S bond in a stepwise manner. Both experimental approaches led us to estimate the E degrees and the intrinsic barrier values for the formation of the radical anions. Comparison of the independently obtained results allowed obtaining, for the first time, a quantitative description of the correlation between heterogeneous and homogeneous rate constants of ETs associated with significant inner reorganization energy. The experimental outcome was fully supported by the theoretical calculations, which provided information about the disulfide lowest unoccupied MOs (LUMOs) and singly occupied MO (SOMO), the bond dissociation energies, and the most significant structural modifications associated with radical anion formation. With disulfides bearing electron-donating or mildly electron-withdrawing groups, the inner reorganization is particularly large, which reflects the significant stretching of the S-S bond experienced by the molecule upon ET. The process entails formation of loose radical anion species in which the SOMO is heavily localized, as the LUMO, onto the frangible bond. As a consequence of the formation of these sigma-radical anions, the S-S bond energy of the latter is rather small and the cleavage rate constant is very large. With electron-withdrawing groups, the extent of delocalization of the

  8. Feijoa sellowiana Berg fruit juice: anti-inflammatory effect and activity on superoxide anion generation.

    Science.gov (United States)

    Monforte, Maria T; Fimiani, Vincenzo; Lanuzza, Francesco; Naccari, Clara; Restuccia, Salvatore; Galati, Enza M

    2014-04-01

    Feijoa sellowiana Berg var. coolidge fruit juice was studied in vivo for the anti-inflammatory activity by carrageenin-induced paw edema test and in vitro for the effects on superoxide anion release from neutrophils in human whole blood. The fruit juice was analyzed by the high-performance liquid chromatography method, and quercetin, ellagic acid, catechin, rutin, eriodictyol, gallic acid, pyrocatechol, syringic acid, and eriocitrin were identified. The results showed a significant anti-inflammatory activity of F. sellowiana fruit juice, sustained also by an effective antioxidant activity observed in preliminary studies on 1,1-diphenyl-2-picrylhydrazyl (DPPH) test. In particular, the anti-inflammatory activity edema inhibition is significant since the first hour (44.11%) and persists until the fifth hour (44.12%) of the treatment. The effect on superoxide anion release was studied in human whole blood, in the presence of activators affecting neutrophils by different mechanisms. The juice showed an inhibiting response on neutrophils basal activity in all experimental conditions. In stimulated neutrophils, the higher inhibition of superoxide anion generation was observed at concentration of 10(-4) and 10(-2) mg/mL in whole blood stimulate with phorbol-myristate-13-acetate (PMA; 20% and 40%) and with N-formyl-methionyl-leucyl-phenylalanine (FMLP; 15% and 48%). The significant reduction of edema and the inhibition of O2(-) production, occurring mainly through interaction with protein-kinase C pathway, confirm the anti-inflammatory effect of F. sellowiana fruit juice.

  9. The superoxide anion donor, potassium superoxide, induces pain and inflammation in mice through production of reactive oxygen species and cyclooxygenase-2.

    Science.gov (United States)

    Maioli, N A; Zarpelon, A C; Mizokami, S S; Calixto-Campos, C; Guazelli, C F S; Hohmann, M S N; Pinho-Ribeiro, F A; Carvalho, T T; Manchope, M F; Ferraz, C R; Casagrande, R; Verri, W A

    2015-04-01

    It is currently accepted that superoxide anion (O2•-) is an important mediator in pain and inflammation. The role of superoxide anion in pain and inflammation has been mainly determined indirectly by modulating its production and inactivation. Direct evidence using potassium superoxide (KO2), a superoxide anion donor, demonstrated that it induced thermal hyperalgesia, as assessed by the Hargreaves method. However, it remains to be determined whether KO2 is capable of inducing other inflammatory and nociceptive responses attributed to superoxide anion. Therefore, in the present study, we investigated the nociceptive and inflammatory effects of KO2. The KO2-induced inflammatory responses evaluated in mice were: mechanical hyperalgesia (electronic version of von Frey filaments), thermal hyperalgesia (hot plate), edema (caliper rule), myeloperoxidase activity (colorimetric assay), overt pain-like behaviors (flinches, time spent licking and writhing score), leukocyte recruitment, oxidative stress, and cyclooxygenase-2 mRNA expression (quantitative PCR). Administration of KO2 induced mechanical hyperalgesia, thermal hyperalgesia, paw edema, leukocyte recruitment, the writhing response, paw flinching, and paw licking in a dose-dependent manner. KO2 also induced time-dependent cyclooxygenase-2 mRNA expression in the paw skin. The nociceptive, inflammatory, and oxidative stress components of KO2-induced responses were responsive to morphine (analgesic opioid), quercetin (antioxidant flavonoid), and/or celecoxib (anti-inflammatory cyclooxygenase-2 inhibitor) treatment. In conclusion, the well-established superoxide anion donor KO2 is a valuable tool for studying the mechanisms and pharmacological susceptibilities of superoxide anion-triggered nociceptive and inflammatory responses ranging from mechanical and thermal hyperalgesia to overt pain-like behaviors, edema, and leukocyte recruitment.

  10. Dehydroepiandrosterone inhibits the spontaneous release of superoxide radical by alveolar macrophages in vitro in asbestosis

    Energy Technology Data Exchange (ETDEWEB)

    Rom, W.N.; Harkin, T. (New York Univ. Medical Center, New York (United States))

    1991-08-01

    Asbestosis is characterized by an alveolar macrophage alveolitis with injury and fibrosis of the lower respiratory tract. Alveolar macrophages recovered by bronchoalveolar lavage spontaneously release exaggerated amounts of oxidants including superoxide anion and hydrogen peroxide that may mediate alveolar epithelial cell injury. Dehydroepiandrosterone (DHEA) is a normally occurring adrenal androgen that inhibits glucose-6-phosphate dehydrogenase, the initial enzyme in the pentose phosphate shunt necessary for NADPH generation and superoxide anion formation. In this regard, the authors hypothesized that DHEA may reduce asbestos-induced oxidant release. DHEA added in vitro to alveolar macrophages lavaged from 11 nonsmoking asbestos workers significantly reduced superoxide anion release. DHEA is an antioxidant and potential anticarcinogenic agent that may have a therapeutic role in reducing the increased oxidant burden in asbestos-induced alveolitis of the lower respiratory tract.

  11. Neutrophil superoxide-anion generating capacity in chronic smoking: effect of long-term -tocopherol therapy

    Indian Academy of Sciences (India)

    Lambertus J Hvan Tits; Frouwkje De Waart; Heidi L M Hak-Lemmers; Jacqueline De Graaf; Pierre N M Demacker; Anton F H Stalenhoef

    2003-02-01

    We investigated whether long-term -tocopherol therapy in chronic smoking affects superoxide generating capacity of neutrophils ex vivo. To this purpose, we randomly assigned 128 male chronic smokers (37 ± 21 pack years of smoking) to treatment with placebo ( = 64) or -tocopherol (400 IU dL--tocopherol daily, = 64). After two years of therapy, we measured phorbol 12-myristate 13-acetate-induced superoxide production of isolated neutrophils and of diluted whole blood by monitoring reduction of ferricytochrome and luminolenhanced peroxidase-catalyzed chemiluminescence. Plasma lipids and lipoproteins were not different between the two treatment groups. As expected, concentrations of -tocopherol in plasma and in low-density lipoproteins were markedly elevated in the supplemented group compared to the placebo group (+ 120%, P < 0.0001 and + 83%, < 0.0001, respectively). Consequently, resistance to in vitro oxidation of low-density lipoproteins (reflected by lag time of conjugated diene formation) was higher in the supplemented group than in the placebo group (+ 22%, < 0.0001). Superoxide generating capacity of neutrophils and superoxide production in diluted whole blood did not differ between -tocopherol and placebo group. It is concluded that in chronic smoking long-term supranormal -tocopherol intake does not reduce neutrophil superoxide-anion generating capacity, despite large increases in the concentrations of -tocopherol in plasma and in low-density lipoproteins.

  12. A two-photon fluorescent probe for exogenous and endogenous superoxide anion imaging in vitro and in vivo.

    Science.gov (United States)

    Li, Run-Qing; Mao, Zhi-Qiang; Rong, Lei; Wu, Nian; Lei, Qi; Zhu, Jing-Yi; Zhuang, Lin; Zhang, Xian-Zheng; Liu, Zhi-Hong

    2017-01-15

    Herein, we report a novel quinoline derivative-based two-photon fluorescent probe 6-(dimethylamino)quinoline-2-benzothiazoline (HQ), which is capable of tracking superoxide anion in organisms with specific "turn-on" fluorescence response based on extension of π-conjugations and moderate ICT process. The probe exhibited favorable photophysical properties, a broad linear range and high photostability. It can specifically detect superoxide anion with a significant fluorescence enhancement and great linearity from 0 to 500μM in PBS buffer. Furthermore, HQ shows low cytotoxicity and excellent photostability toward living cells and organisms, which was able to monitor endogenous superoxide anion fluxes in living cells and in vivo. For the first time, endogenous superoxide anion in lung inflammation was visualized successfully by using HQ through two-photon microscopy, and the probe HQ shows great potential for fast in-situ detecting of inflammatory response in live organisms.

  13. SK-N-MC cell death occurs by distinct molecular mechanisms in response to hydrogen peroxide and superoxide anions: involvements of JAK2-STAT3, JNK, and p38 MAP kinases pathways.

    Science.gov (United States)

    Moslehi, Maryam; Yazdanparast, Razieh

    2013-07-01

    Oxidative stress plays a vital role in the pathogenesis of neurodegenerative diseases. Nerve cells are incessantly exposed to environmental stresses leading to overproduction of some harmful species like reactive oxygen species (ROS). ROS including hydrogen peroxide and superoxide anion are potent inducers of various signaling pathways encompassing MAPKs and JAK-STAT pathways. In the current study, we scrutinized the effects of hydrogen peroxide and/or menadione (superoxide anion generator) on JNK/p38-MAPKs and JAK2-STAT3 pathways to elucidate the mechanism(s) by which each oxidant modulated the above-mentioned pathways leading to SK-N-MC cell death. Our results delineated that hydrogen peroxide and superoxide anion radical induced distinct responses as we showed that STAT3 and p38 were activated in response to hydrogen peroxide, but not superoxide anion radicals indicating the specificity in ROS-induced signaling pathways activations and behaviors. We also observed that menadione induced JNK-dependent p53 expression and apoptotic death in SK-N-MC cells while H2O2-induced JNK activation was p53 independent. Thus, we declare that ROS type has a key role in selective instigation of JNK/p38-MAPKs and JAK2-STAT3 pathways in SK-N-MC cells. Identifying these differential behaviors and mechanisms of hydrogen peroxide and superoxide anion functions illuminates the possible therapeutic targets in the prevention or treatment of ROS-induced neurodegenerative diseases such as Alzheimer's disease.

  14. Repair effect of thymine radical anion by echinocoside using pulse radiolysis

    Institute of Scientific and Technical Information of China (English)

    李雯艳; 郑荣梁; 赵松岭; 姜岳; 林念芸

    1996-01-01

    Repair activities of thymine radical anion by echinocoside, isolated from Pedicularis plicata. were studied using pulse radiolysis technique. The thymine radical anion was produced by the reaction of hydrated electron with thymine. Echinocoside. one of the polyphenols of phenylpropanoid glycoside, was added to the thymine aqueous solution saturated with N2. Kinetic analysis by transient absorption spectrum showed that thymine radical anion was formed at first, and then after several decades of microseconds of pulse radiolysis. the spectrum of thymine radical anion was changed to that of echinocoside radical anion. The evidence indicated that thymine radical anion was repaired through one-electron-transfer between the DNA base radical anion and echinocoside. The rate constant of electron transfer by echinocoside was 1.45× 109 dm3 · mol1 · s 1.

  15. Immobilization of superoxide dismutase on Pt-Pd/MWCNTs hybrid modified electrode surface for superoxide anion detection.

    Science.gov (United States)

    Zhu, Xiang; Niu, Xiangheng; Zhao, Hongli; Tang, Jie; Lan, Minbo

    2015-05-15

    Monitoring of reactive oxygen species like superoxide anion (O2(∙-)) turns to be of increasing significance considering their potential damages to organism. In the present work, we fabricated a novel O2(∙-) electrochemical sensor through immobilizing superoxide dismutase (SOD) onto a Pt-Pd/MWCNTs hybrid modified electrode surface. The Pt-Pd/MWCNTs hybrid was synthesized via a facile one-step alcohol-reduction process, and well characterized by transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The immobilization of SOD was accomplished using a simple drop-casting method, and the performance of the assembled enzyme-based sensor for O2(∙-) detection was systematically investigated by several electrochemcial techniques. Thanks to the specific biocatalysis of SOD towards O2(∙-) and the Pt-Pd/MWCNTs - promoted fast electron transfer at the fabricated interface, the developed biosensor exhibits a fast, selective and linear amperometric response upon O2(∙-) in the concentration scope of 40-1550 μM (R(2)=0.9941), with a sensitivity of 0.601 mA cm(-2) mM(-1) and a detection limit of 0.71 μM (S/N=3). In addition, the favorable biocompatibility of this electrode interface endows the prepared biosensor with excellent long-term stability (a sensitivity loss of only 3% over a period of 30 days). It is promising that the proposed sensor will be utilized as an effective tool to quantitatively monitor the dynamic changes of O2(∙-) in biological systems.

  16. The TOM complex is involved in the release of superoxide anion from mitochondria.

    Science.gov (United States)

    Budzińska, Małgorzata; Gałgańska, Hanna; Karachitos, Andonis; Wojtkowska, Małgorzata; Kmita, Hanna

    2009-08-01

    Available data indicate that superoxide anion (O(2)(*-) ) is released from mitochondria, but apart from VDAC (voltage dependent anion channel), the proteins involved in its transport across the mitochondrial outer membrane still remain elusive. Using mitochondria of the yeast Saccharomyces cerevisiae mutant depleted of VDAC (Deltapor1 mutant) and the isogenic wild type, we studied the role of the TOM complex (translocase of the outer membrane) in the efflux of O(2)(*-) from the mitochondria. We found that blocking the TOM complex with the fusion protein pb(2)-DHFR decreased O(2)(*-) release, particularly in the case of Deltapor1 mitochondria. We also observed that the effect of the TOM complex blockage on O(2)(*-) release from mitochondria coincided with the levels of O(2)(*-) release as well as with levels of Tom40 expression in the mitochondria. Thus, we conclude that the TOM complex participates in O(2)(*-) release from mitochondria.

  17. Oxidation of silicon surface with atomic oxygen radical anions

    Institute of Scientific and Technical Information of China (English)

    Wang Lian; Song Chong-Fu; Sun Jian-Qiu; Hou Ying; Li Xiao-Guang; Li Quan-Xin

    2008-01-01

    The surface oxidation of silicon (Si) wafers by atomic oxygen radical anions (O- anions) and the preparation of metal-oxide-semiconductor (MOS) capacitors on the O--oxidized Si substrates have been examined for the first time. The O- anions are generated from a recently developed O- storage-emission material of [Ca24Al28O64]4+.4O- (C12A7-O- for short). After it has been irradiated by an O- anion beam (0.5 μA/cm2) at 300℃ for 1-10 hours, the Si wafer achieves an oxide layer with a thickness ranging from 8 to 32 nm. X-ray photoelectron spectroscopy (XPS) results reveal that the oxide layer is of a mixture of SiO2, Si2O3, and Si2O distributed in different oxidation depths. The features of the MOS capacitor of are investigated by measuring capacitance-voltage (C - V) and current-voltage (Ⅰ - Ⅴ) curves. The oxide charge density is about 6.0×1011 cm-2 derived from the C - V curves. The leakage current density is in the order of 10-6 A/cm2 below 4 MV/cm, obtained from the Ⅰ - Ⅴ curves. The Oanions formed by present method would have potential applications to the oxidation and the surface-modification of materials together with the preparation of semiconductor devices.

  18. Ab initio molecular dynamics of the reaction of quercetin with superoxide radical

    Science.gov (United States)

    Lespade, Laure

    2016-08-01

    Superoxide plays an important role in biology but in unregulated concentrations it is implicated in a lot of diseases such as cancer or atherosclerosis. Antioxidants like flavonoids are abundant in plant and are good scavengers of superoxide radical. The modeling of superoxide scavenging by flavonoids from the diet still remains a challenge. In this study, ab initio molecular dynamics of the reaction of the flavonoid quercetin toward superoxide radical has been carried out using Car-Parrinello density functional theory. The study has proven different reactant solvation by modifying the number of water molecules surrounding superoxide. The reaction consists in the gift of a hydrogen atom of one of the hydroxyl groups of quercetin to the radical. When it occurs, it is relatively fast, lower than 100 fs. Calculations show that it depends largely on the environment of the hydroxyl group giving its hydrogen atom, the geometry of the first water layer and the presence of a certain number of water molecules in the second layer, indicating a great influence of the solvent on the reactivity.

  19. Charge transfer from 2-aminopurine radical cation and radical anion to nucleobases: A pulse radiolysis study

    Energy Technology Data Exchange (ETDEWEB)

    Manoj, P. [School of Chemical Sciences, Mahatma Gandhi University, Kottayam 686 560, Kerala (India); Mohan, H. [Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Mittal, J.P. [Radiation Chemistry and Chemical Dynamics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Manoj, V.M. [School of Chemical Sciences, Mahatma Gandhi University, Kottayam 686 560, Kerala (India); Aravindakumar, C.T. [School of Chemical Sciences, Mahatma Gandhi University, Kottayam 686 560, Kerala (India)], E-mail: CT-Aravindakumar@rocketmail.com

    2007-01-08

    Pulse radiolysis study has been carried out to investigate the properties of the radical cation of 2-aminopurine (2AP) and the probable charge transfer from the radical cation and radical anion of 2AP to natural nucleobases in aqueous medium. The radical cation of 2AP was produced by the reaction of sulfate radical anion (SO{sub 4}{sup dot-}). The time resolved absorption spectra obtained by the reaction of SO{sub 4}{sup dot-} with 2AP at neutral pH have two distinct maxima at 380 and 470nm and is assigned to the formation of a neutral radical of the form 2AP-N{sup 2}(-H){sup dot} (k{sub 2}=4.7x10{sup 9}dm{sup 3}mol{sup -1}s{sup -1} at pH 7). This neutral radical is formed from the deprotonation reaction of a very short-lived radical cation of 2AP. The transient absorption spectra recorded at pH 10.2 have two distinct maxima at 400 and 480nm and is assigned to the formation of a nitrogen centered radical (2AP-N(9){sup dot}). As the hole transport from 2AP to guanine is a highly probable process, the reaction of SO{sub 4}{sup dot-} is carried out in the presence of guanosine, adenosine and inosine. The spectrum obtained in the presence of guanosine was significantly different from that in the absence and it showed prominent absorption maxima at 380 and 470nm, and a weak broad maximum centered around 625nm which match well with the reported spectrum of a neutral guanine radical (G(-H){sup dot}). The electron transfer reaction from the radical anion of 2AP to thymine (T), cytidine (Cyd) and uridine (Urd) was also investigated at neutral pH. Among the three pyrimidines, only the transient spectrum in the presence of T gave a significant difference from the spectral features of the electron adduct of 2AP, which showed a prominent absorption maximum at 340nm and this spectrum is similar to the electron adduct spectrum of T. The preferential reduction of thymine by 2AP{sup dot-} and the oxidation of guanosine by 2AP{sup dot+} clearly follow the oxidation

  20. Direct determination of rate constants for coupling between aromatic radical anions and alkyl and benzyl radicals by laser-flash photolysis

    DEFF Research Database (Denmark)

    Lund, T.; Christensen, P.; Wilbrandt, Robert Walter

    2003-01-01

    Coupling rates between the radicals methyl, n-, sec-, tert-butyl and benzyl (R-.) and the aromatic radical anions of 1,4-dicyanonaphthalene, 9,10-dicyanoanthracene and fluorenone (A(-.)) have been obtained using a new laser-flash photolysis method. The radicals R-. and the radical anions A(-.) were...... generated by a photoinduced electron transfer reaction between the aromatic compound A and the alkyl or benzyl triphenylborate anion RB(Ph)(3)(-). For the first time the rate constants of the coupling reaction between methyl and benzyl radicals with aromatic radical anions have been obtained. For all...... of the radicals and the structure and standard potentials of the aromatic radical anions....

  1. A nitro radical anion formation from nifedipine: an electrochemical approach.

    Science.gov (United States)

    Squella, J A; Solabarrieta, C; Nuñez-Vergara, L J

    1993-12-01

    The cyclic voltammetric behaviour of nifedipine was studied. The addition of three aprotic solvents to nifedipine in an aqueous citrate buffer system was examined. Qualitatively they result in separation of the initial irreversible 4 electron reduction into two stages, the NO2/RNO2.- and RNO2.-, 4H/RNHOH, H2O couples, respectively. Particular attention was directed to the 1-electron RNO2/RNO2.- couple as measured by the cyclic voltammetric mode in mixed media. Analysis of the cyclic voltammetric response as a function of scan rate and non-aqueous solvent content yields information on the stability of the radical anion. The chemical forward reaction of the radical anion follows a second order kinetics with a stability constant of 1.1 x 10(-3) l mol-1 s-1 and a half-life time of 0.09 s for 1 mM of nifedipine in aqueous citrate buffer, pH 7.4/DMF; 50:50.

  2. Ammoniated electron as a solvent stabilized multimer radical anion

    CERN Document Server

    Shkrob, I A

    2005-01-01

    The excess electron in liquid ammonia ("ammoniated electron") is commonly viewed as a cavity electron in which the s-type wave function fills the interstitial void between 6-9 ammonia molecules. Herewith an alternative model is examined in which the ammoniated electron is regarded as a solvent stabilized multimer radical anion, as was originally suggested by Symons [Chem. Soc. Rev. 1976, 5, 337]. In this model, most of the excess electron density resides in the frontier orbitals of N atoms in the ammonia molecules forming the solvation cavity; a fraction of this spin density is transferred to the molecules in the second solvation shell. The cavity is formed due to the repulsion between negatively charged solvent molecules. Using density functional theory calculations for small ammonia cluster anions in the gas phase, it is demonstrated that such core anions would quantitatively account for the observed pattern of Knight shifts for 1H and 14N nuclei as observed by NMR spectroscopy and the downshifted stretchin...

  3. Triterpenoids and Steroids from Ganoderma mastoporum and Their Inhibitory Effects on Superoxide Anion Generation and Elastase Release

    Directory of Open Access Journals (Sweden)

    Tran Dinh Thang

    2013-11-01

    Full Text Available The methanol extracts of the fruiting bodies of Ganoderma mastoporum collected in Vietnam was purified to afford eight compounds, including three triterpenoids and five steroids. The purified compounds were examined for their inhibitory effects against superoxide anion generation and elastase release. Among the tested compounds, ergosta-4,6,8(14,22-tetraen-3-one (3 exhibited the most significant inhibition towards superoxide anion generation and elastase release with IC50 values of 2.30 ± 0.38 and 1.94 ± 0.50 µg/mL, respectively.

  4. Rapid reaction of nanomolar Mn(II) with superoxide radical in seawater and simulated freshwater

    Science.gov (United States)

    Hansard, S.P.; Easter, H.D.; Voelker, B.M.

    2011-01-01

    Superoxide radical (O2-) has been proposed to be an important participant in oxidation-reduction reactions of metal ions in natural waters. Here, we studied the reaction of nanomolar Mn(II) with O 2- in seawater and simulated freshwater, using chemiluminescence detection of O2- to quantify the effect of Mn(II) on the decay kinetics of O2-. With 3-24 nM added [Mn(II)] and superoxide could maintain a significant fraction of dissolved Mn in the +III oxidation state. ?? 2011 American Chemical Society.

  5. [Generation of superoxide radicals by the mitochondrial respiratory chain of isolated cardiomyocytes].

    Science.gov (United States)

    Kashkarov, K P; Vasil'eva, E V; Ruuge, E K

    1994-06-01

    Generation of superoxide radicals by the mitochondrial respiratory chain of cardiomyocites isolated from rat heart and treated with saponin was studied. The rate of O2- production was measured by electron paramagnetic resonance (EPR) spectroscopy using hydroxylamine TEMPONE-H as spin trap. A device has been constructed which provided permanent stirring of cardiomyocyte samples directly in the cavity and prevented cell aggregation. When substrates and antimycin A and/or rotenone are added, the radical production rate increased and reached its maximum in the presence of the both inhibitors. Superoxide dismutase as well as KCN suppressed the radical production, thus being suggestive of the generation of superoxide radicals in the bc1 complex, while the mechanism of O2- production is the same as was suggested for isolated mitochondria. The ratio between rates of O2- generation by isolated cardiomyocytes under various experimental conditions is in a good accord with corresponding parameter of isolated mitochondria. However, in the case of cardiomyocytes the absolute values of the O2- production rate are approximately twice as high as those in isolated mitochondria, presumably due to the partial damage of the mitochondrial respiratory chain during the isolation procedure.

  6. Utilization of superoxide anion by indoleamine oxygenase-catalyzed tryptophan and indoleamine oxidation.

    Science.gov (United States)

    Hayaishi, O

    1996-01-01

    The following is our current working hypothesis concerning the biological significance of IDO induction. When tissues are invaded by virus, bacteria, or parasites, leukocytes and lymphocytes will accumulate at the site and interferon will be produced by these cells in the inflammatory loci. The interferon thus produced is released and interacts with the cell surface to trigger IDO induction in the same or other types of cells. As a consequence of inflammation, superoxide anion is liberated and serves as a substrate for IDO. Although it is possible that some trytophan metabolites may activate the immune system or act as bacteriostatic agents, available evidence does not support this hypothesis. We therefore tentatively conclude that tryptophan is degraded by IDO and depleted, whereby the growth of viruses, bacteria and certain parasites is inhibited, because tryptophan is the least available and therefore most important essential amino acid for their growth.

  7. Production of superoxide anions by keratinocytes initiates P. acnes-induced inflammation of the skin.

    Directory of Open Access Journals (Sweden)

    Philippe A Grange

    2009-07-01

    Full Text Available Acne vulgaris is a chronic inflammatory disorder of the sebaceous follicles. Propionibacterium acnes (P. acnes, a gram-positive anareobic bacterium, plays a critical role in the development of these inflammatory lesions. This study aimed at determining whether reactive oxygen species (ROS are produced by keratinocytes upon P. acnes infection, dissecting the mechanism of this production, and investigating how this phenomenon integrates in the general inflammatory response induced by P. acnes. In our hands, ROS, and especially superoxide anions (O2(*-, were rapidly produced by keratinocytes upon stimulation by P. acnes surface proteins. In P. acnes-stimulated keratinocytes, O2(*- was produced by NAD(PH oxidase through activation of the scavenger receptor CD36. O2(*- was dismuted by superoxide dismutase to form hydrogen peroxide which was further detoxified into water by the GSH/GPx system. In addition, P. acnes-induced O2(*- abrogated P. acnes growth and was involved in keratinocyte lysis through the combination of O2(*- with nitric oxide to form peroxynitrites. Finally, retinoic acid derivates, the most efficient anti-acneic drugs, prevent O2(*- production, IL-8 release and keratinocyte apoptosis, suggesting the relevance of this pathway in humans.

  8. Generation of naphthoquinone radical anions by electrospray ionization: solution, gas-phase, and computational chemistry studies.

    Science.gov (United States)

    Vessecchi, Ricardo; Naal, Zeki; Lopes, José N C; Galembeck, Sérgio E; Lopes, Norberto P

    2011-06-02

    Radical anions are present in several chemical processes, and understanding the reactivity of these species may be described by their thermodynamic properties. Over the last years, the formation of radical ions in the gas phase has been an important issue concerning electrospray ionization mass spectrometry studies. In this work, we report on the generation of radical anions of quinonoid compounds (Q) by electrospray ionization mass spectrometry. The balance between radical anion formation and the deprotonated molecule is also analyzed by influence of the experimental parameters (gas-phase acidity, electron affinity, and reduction potential) and solvent system employed. The gas-phase parameters for formation of radical species and deprotonated species were achieved on the basis of computational thermochemistry. The solution effects on the formation of radical anion (Q(•-)) and dianion (Q(2-)) were evaluated on the basis of cyclic voltammetry analysis and the reduction potentials compared with calculated electron affinities. The occurrence of unexpected ions [Q+15](-) was described as being a reaction between the solvent system and the radical anion, Q(•-). The gas-phase chemistry of the electrosprayed radical anions was obtained by collisional-induced dissociation and compared to the relative energy calculations. These results are important for understanding the formation and reactivity of radical anions and to establish their correlation with the reducing properties by electrospray ionization analyses.

  9. Superoxide anions and hydrogen peroxide induce hepatocyte death by different mechanisms : Involvement of JNK and ERK MAP kinases

    NARCIS (Netherlands)

    Conde de la Rosa, L; Schoemaker, MH; Vrenken, TE; Buist-Homan, M; Havinga, R; Jansen, PLM; Moshage, H

    2006-01-01

    Background/Aims: In liver diseases, reactive oxygen species (ROS) are involved in cell death and liver injury, but the mechanisms are not completely elucidated. To elucidate the mechanisms of hepatocyte cell death induced by the ROS superoxide anions and hydrogen peroxide, primary cultures of hepato

  10. Structures and energies of the radicals and anions generated from chlorpyrifos.

    Science.gov (United States)

    Zhang, Yi; Liu, Chang-Zhong; Li, Xiao-Jun; Wang, Zi-Liang; Zhang, Hai-Tang; Miao, Zhi-Guo

    2010-08-01

    The radicals and anions generated from chlorpyrifos by removing a hydrogen atom have been investigated using the hybrid density functional B3PW91 method. The results show that all the radicals have been classified as three groups and their stability order is methylene (radical 1, 3, 5, and 7) > methyl (radical 9, 11 and 13) > ring (15); the anions have the relative energetic order: methyl > methylene > ring. Moreover, some decomposition reactions are also reported. The large HOMO-LUMO gaps indicate that both radicals and anions are predicted to be high-kinetic stable molecules. We also find that radicals 9, 11 and 13 have the highest AEAs and anions 2, 4 and 6 have higher VDEs. Additionally, natural population analysis charges show that there is the lowest Deltaq (0.14) for the C7 and C9 atoms. We hope that our theoretical results may provide a reference for further experiment and practical application.

  11. Parthenolide induces superoxide anion production by stimulating EGF receptor in MDA-MB-231 breast cancer cells.

    Science.gov (United States)

    D'Anneo, A; Carlisi, D; Emanuele, S; Buttitta, G; Di Fiore, R; Vento, R; Tesoriere, G; Lauricella, M

    2013-12-01

    The sesquiterpene lactone parthenolide (PN) has recently attracted considerable attention because of its anti-microbial, anti-inflammatory and anticancer effects. However, the mechanism of its cytotoxic action on tumor cells remains scarcely defined. We recently provided evidence that the effect exerted by PN in MDA-MB-231 breast cancer cells was mediated by the production of reactive oxygen species (ROS). The present study shows that PN promoted the phosphorylation of EGF receptor (phospho-EGFR) at Tyr1173, an event which was observed already at 1 h of incubation with 25 µM PN and reached a peak at 8-16 h. This effect seemed to be a consequence of ROS production, because N-acetylcysteine (NAC), a powerful ROS scavenger, prevented the increment of phospho-EGFR levels. In addition fluorescence analyses performed using dihydroethidium demonstrated that PN stimulated the production of superoxide anion already at 2-3 h of incubation and the effect further increased prolonging the time of treatment, reaching a peak at 8-16 h. Superoxide anion production was markedly hampered by apocynin, a well known NADPH oxidase (NOX) inhibitor, suggesting that the effect was dependent on NOX activity. The finding that AG1478, an EGFR kinase inhibitor, substantially blocked both EGFR phosphorylation and superoxide anion production strongly suggested that phosphorylation of EGFR can be responsible for the activation of NOX with the consequent production of superoxide anion. Therefore, EGFR phosphorylation can exert a key role in the production of superoxide anion and ROS induced by PN in MDA-MB-231 cells.

  12. Detection of superoxide radicals in tomato plants exposed to salinity, drought, cold and heavy metal stress using CMC-G-SOD biosensor.

    Science.gov (United States)

    Kocabay, Ozge; Emregul, Emel; Aydın, Semra Soydan; Aras, Sumer

    2013-10-01

    A novel highly sensitive electrochemical carboxymethylcellulose-gelatin-superoxide dismutase biosensor was used for the determination of superoxide radicals enhancement in tomato plants exposed to salinity, drought, cold and heavy metal stress. The variations in superoxide radicals depending on abiotic stress was determined using biosensor. The superoxide radical production with regard to control rapidly was increased in tomato plants exposed to salinity, drought, cold and heavy metal stress. The superoxide radical enhancement in tomato plants exposed to salinity, drought, cold and heavy metal stress was successfully determined using carboxymethylcellulose-gelatin-superoxide dismutase biosensor.

  13. Rapid reaction of superoxide with insulin-tyrosyl radicals to generate a hydroperoxide with subsequent glutathione addition.

    Science.gov (United States)

    Das, Andrew B; Nauser, Thomas; Koppenol, Willem H; Kettle, Anthony J; Winterbourn, Christine C; Nagy, Péter

    2014-05-01

    Tyrosine (Tyr) residues are major sites of radical generation during protein oxidation. We used insulin as a model to study the kinetics, mechanisms, and products of the reactions of radiation-induced or enzyme-generated protein-tyrosyl radicals with superoxide to demonstrate the feasibility of these reactions under oxidative stress conditions. We found that insulin-tyrosyl radicals combined to form dimers, mostly via the tyrosine at position 14 on the α chain (Tyr14). However, in the presence of superoxide, dimerization was largely outcompeted by the reaction of superoxide with insulin-tyrosyl radicals. Using pulse radiolysis, we measured a second-order rate constant for the latter reaction of (6±1) × 10(8) M(-1) s(-1) at pH 7.3, representing the first measured rate constant for a protein-tyrosyl radical with superoxide. Mass-spectrometry-based product analyses revealed the addition of superoxide to the insulin-Tyr14 radical to form the hydroperoxide. Glutathione efficiently reduced the hydroperoxide to the corresponding monoxide and also subsequently underwent Michael addition to the monoxide to give a diglutathionylated protein adduct. Although much slower, conjugation of the backbone amide group can form a bicyclic Tyr-monoxide derivative, allowing the addition of only one glutathione molecule. These findings suggest that Tyr-hydroperoxides should readily form on proteins under oxidative stress conditions where protein radicals and superoxide are both generated and that these should form addition products with thiol compounds such as glutathione.

  14. Synthesis of decacationic [60]fullerene decaiodides giving photoinduced production of superoxide radicals and effective PDT-mediation on antimicrobial photoinactivation.

    Science.gov (United States)

    Wang, Min; Maragani, Satyanarayana; Huang, Liyi; Jeon, Seaho; Canteenwala, Taizoon; Hamblin, Michael R; Chiang, Long Y

    2013-05-01

    We report a novel class of highly water-soluble decacationic methano[60]fullerene decaiodides C60[>M(C3N6(+)C3)2]-(I(-))10 [1-(I(-))10] capable of co-producing singlet oxygen (Type-II) and highly reactive hydroxyl radicals, formed from superoxide radicals in Type-I photosensitizing reactions, upon illumination at both UVA and white light wavelengths. The O2(-)·-production efficiency of 1-(I(-))10 was confirmed by using an O2(-)·-reactive bis(2,4-dinitrobenzenesulfonyl)tetrafluorofluorescein probe and correlated to the photoinduced electron-transfer event going from iodide anions to (3)C60*[>M(C3N6(+)C3)2] leading to C60(-)·[>M(C3N6(+)C3)2]. Incorporation of a defined number (ten) of quaternary ammonium cationic charges per C60 in 1 was aimed to enhance its ability to target pathogenic Gram-positive and Gram-negative bacterial cells. We used the well-characterized malonato[60]fullerene diester monoadduct C60[>M(t-Bu)2] as the starting fullerene derivative to provide a better synthetic route to C60[>M(C3N6(+)C3)2] via transesterification reaction under trifluoroacetic acid catalyzed conditions. These compounds may be used as effective photosensitizers and nano-PDT drugs for photoinactivation of pathogens.

  15. Pyrrolidine dithiocarbamate inhibits superoxide anion-induced pain and inflammation in the paw skin and spinal cord by targeting NF-κB and oxidative stress.

    Science.gov (United States)

    Pinho-Ribeiro, Felipe A; Fattori, Victor; Zarpelon, Ana C; Borghi, Sergio M; Staurengo-Ferrari, Larissa; Carvalho, Thacyana T; Alves-Filho, Jose C; Cunha, Fernando Q; Cunha, Thiago M; Casagrande, Rubia; Verri, Waldiceu A

    2016-06-01

    We evaluated the effect of pyrrolidine dithiocarbamate (PDTC) in superoxide anion-induced inflammatory pain. Male Swiss mice were treated with PDTC and stimulated with an intraplantar or intraperitoneal injection of potassium superoxide, a superoxide anion donor. Subcutaneous PDTC treatment attenuated mechanical hyperalgesia, thermal hyperalgesia, paw oedema and leukocyte recruitment (neutrophils and macrophages). Intraplantar injection of superoxide anion activated NF-κB and increased cytokine production (IL-1β, TNF-α and IL-10) and oxidative stress (nitrite and lipid peroxidation levels) at the primary inflammatory foci and in the spinal cord (L4-L6). PDTC treatment inhibited superoxide anion-induced NF-κB activation, cytokine production and oxidative stress in the paw and spinal cord. Furthermore, intrathecal administration of PDTC successfully inhibited superoxide anion-induced mechanical hyperalgesia, thermal hyperalgesia and inflammatory response in peripheral foci (paw). These results suggest that peripheral stimulus with superoxide anion activates the local and spinal cord oxidative- and NF-κB-dependent inflammatory nociceptive mechanisms. PDTC targets these events, therefore, inhibiting superoxide anion-induced inflammatory pain in mice.

  16. Inhibitory effects of N-acetylcysteine on superoxide anion generation in human polymorphonuclear leukocytes.

    Science.gov (United States)

    Villagrasa, V; Cortijo, J; Martí-Cabrera, M; Ortiz, J L; Berto, L; Esteras, A; Bruseghini, L; Morcillo, E J

    1997-05-01

    It has been suggested that reactive oxygen species released by activated polymorphonuclear leukocytes (PMN) in man is one mechanism of tissue injury. Therapeutic action aimed at increasing antioxidant defence mechanisms is still a clinical challenge. This study examines the activity of N-acetylcysteine, a known antioxidant, in the protection of PMN exposed in-vitro to the chemoattractant peptide fMet-Leu-Phe (FMLP), the protein kinase C activator phorbol myristate acetate or the lipid peroxidation promoter t-butyl hydroperoxide. FMLP (3-300 nM) and phorbol myristate acetate (160 pm-160 nM) induced concentration-related superoxide anion generation. Pre-treatment with N-acetylcysteine (33-333 microM) resulted in concentration-related inhibition of superoxide production induced by FMLP (30 nM) or phorbol myristate acetate (16 nM);-log IC50 values were 3.97 +/- 0.07 and 3.91 +/- 0.10, respectively. Changes in intracellular calcium ion concentration ([Ca2+]i) induced by FMLP (30 nM) were studied in fura-2-loaded human PMN. FMLP produced a transient calcium response, i.e. a peak followed by decay to a residual value above baseline. N-Acetylcysteine (333 microM) did not affect either basal [Ca2+]i values or changes in [Ca2+]i values after treatment with FMLP. Activation by phorbol myristate acetate caused a reduction in glutathione levels from 5.94 +/- 0.86 (control) to 1.84 +/- 0.51 nmol/3 x 10(6) cells (P 0.05 compared with control). Exposure to t-butyl hydroperoxide (0.5 mM, 30 min) markedly increased malondialdehyde levels (from 0.03 +/- 0.02 to 0.73 +/- 0.07 nmol/10(6) cells), and index of lipid peroxidation. Malondialdehyde levels were significantly reduced in PMN treated with N-acetylcysteine (333 microM; 0.55 +/- 0.04 nmol/10(6) cells; P < 0.05 compared with untreated cells exposed to t-butyl hydroperoxide). In conclusion, N-acetylcysteine reduces superoxide generation in response to FMLP and phorbol myristate acetate and partially protects against lipid

  17. Structure and Reactivity of the N-Acetyl-Cysteine Radical Cation and Anion: Does Radical Migration Occur?

    NARCIS (Netherlands)

    Osburn, S.; G. Berden,; Oomens, J.; O' Hair, R. A. J.; Ryzhov, V.

    2011-01-01

    The structure and reactivity of the N-acetyl-cysteine radical cation and anion were studied using ion-molecule reactions, infrared multi-photon dissociation (IRMPD) spectroscopy, and density functional theory (DFT) calculations. The radical cation was generated by first nitrosylating the thiol of N-

  18. Structure and reactivity of the N-acetyl-cysteine radical cation and anion: does radical migration occur?

    NARCIS (Netherlands)

    Osburn, S.; Berden, G.; Oomens, J.; O'Hair, R.A.J.; Ryzhov, V.

    2011-01-01

    The structure and reactivity of the N-acetyl-cysteine radical cation and anion were studied using ion-molecule reactions, infrared multi-photon dissociation (IRMPD) spectroscopy, and density functional theory (DFT) calculations. The radical cation was generated by first nitrosylating the thiol of N-

  19. Structure and Reactivity of the N-Acetyl-Cysteine Radical Cation and Anion: Does Radical Migration Occur?

    NARCIS (Netherlands)

    Osburn, S.; G. Berden,; Oomens, J.; O' Hair, R. A. J.; Ryzhov, V.

    2011-01-01

    The structure and reactivity of the N-acetyl-cysteine radical cation and anion were studied using ion-molecule reactions, infrared multi-photon dissociation (IRMPD) spectroscopy, and density functional theory (DFT) calculations. The radical cation was generated by first nitrosylating the thiol of N-

  20. Structure and reactivity of the N-acetyl-cysteine radical cation and anion: does radical migration occur?

    NARCIS (Netherlands)

    Osburn, S.; Berden, G.; Oomens, J.; O'Hair, R.A.J.; Ryzhov, V.

    2011-01-01

    The structure and reactivity of the N-acetyl-cysteine radical cation and anion were studied using ion-molecule reactions, infrared multi-photon dissociation (IRMPD) spectroscopy, and density functional theory (DFT) calculations. The radical cation was generated by first nitrosylating the thiol of N-

  1. Structure and Reactivity of the N-Acetyl-Cysteine Radical Cation and Anion: Does Radical Migration Occur?

    NARCIS (Netherlands)

    Osburn, S.; G. Berden,; Oomens, J.; O' Hair, R. A. J.; Ryzhov, V.

    2011-01-01

    The structure and reactivity of the N-acetyl-cysteine radical cation and anion were studied using ion-molecule reactions, infrared multi-photon dissociation (IRMPD) spectroscopy, and density functional theory (DFT) calculations. The radical cation was generated by first nitrosylating the thiol of

  2. Structure and reactivity of the N-acetyl-cysteine radical cation and anion: does radical migration occur?

    NARCIS (Netherlands)

    Osburn, S.; Berden, G.; Oomens, J.; O'Hair, R.A.J.; Ryzhov, V.

    2011-01-01

    The structure and reactivity of the N-acetyl-cysteine radical cation and anion were studied using ion-molecule reactions, infrared multi-photon dissociation (IRMPD) spectroscopy, and density functional theory (DFT) calculations. The radical cation was generated by first nitrosylating the thiol of

  3. Activation/driving force relationships for cyclopropylcarbinyl --> homoallyl-type rearrangements of radical anions.

    Science.gov (United States)

    Chahma, M'hamed; Li, Xiangzhong; Phillips, J Paige; Schwartz, Phillip; Brammer, Larry E; Wang, Yonghui; Tanko, James M

    2005-04-21

    By using direct and indirect electrochemical methods, rate constants (ko) for cyclopropane ring opening of radical anions derived from the one-electron reduction of trans-1-benzoyl-2-phenylcyclopropane, trans-1-benzoyl-2-vinylcyclopropane, 2-methylenecyclopropyl phenyl ketone, spiro[anthracene-9,1'-cyclopropan-10-one], 3-cyclopropylcyclohex-2-en-1-one, and 3-(1-methylcyclopropyl)cyclohex-2-en-1-one were determined. Qualitatively, rate constants for ring opening of these (and other cyclopropyl- and cyclobutyl-containing radical anions) can be rationalized on the basis of the thermodynamic stability of the radical anion, the ability of substituents on the cyclopropyl group to stabilize the radical portion of the distonic radical anion, and the stability of the enolate portion of the distonic radical anion. On the basis of this notion, a thermochemical cycle for estimating deltaG(o) for ring opening was presented. For simple cyclopropyl-containing ketyl anions, a reasonable correlation between log(ko) and deltaG(o) was found, and stepwise dissociative electron transfer theory was applied to rationalize the results. Activation energies calculated with density functional theory (UB3LYP/6-31+G*) correlate reasonably well with measured log(ko). The derived log(ko) and deltaG(o) and log(ko) vs E(a) plots provide the basis for a "calibration curve" to predict rate constants for ring opening of radical anions derived from carbonyl compounds, in general.

  4. Superoxide anion production by human spermatozoa as a part of the ionophore-induced acrosome reaction process.

    Science.gov (United States)

    Griveau, J F; Renard, P; Le Lannou, D

    1995-04-01

    The involvement of superoxide anion (O2o-) in human sperm capacitation and/or acrosome reaction was investigated. Addition of superoxide dismutase (SOD) to the medium at the beginning of the capacitation process or 15 min before induction of the acrosome reaction, decreased the level of ionophore-induced acrosome reaction. Hyperactivation was unaffected by the presence of SOD during the capacitation process. Addition of calcium ionophore to the sperm suspension increased production of O2o- by the spermatozoa by four to five-fold and induced the acrosome reaction. In the presence of SOD, superoxide anion could not be detected in the medium and the rate of induced-acrosome reaction was decreased greatly. The presence of an inhibitor of protein kinase C inhibited the production of O2o- in the medium and reduced the induced-acrosome reaction. The production of O2o- and the acrosome reaction were also increased by exposure of spermatozoa to 12-myristate 13-acetate phorbol ester, a specific activator of protein kinase C. While the level of spontaneous acrosome reaction was not increased by the direct addition of O2o- to the medium, its presence induced the release of unesterified fatty acids from membrane phospholipids. These findings suggest that the production of O2o- by spermatozoa could be involved in the ionophore-induced acrosome reaction, possibly through the de-esterification of membrane phospholipids. However, this production of superoxide anion is not sufficient on its own to induce the acrosome reaction.

  5. Inactivation of Bacillus Subtilis by Atomic Oxygen Radical Anion

    Institute of Scientific and Technical Information of China (English)

    LI Longchun; WANG Lian; YU Zhou; LV Xuanzhong; LI Quanxin

    2007-01-01

    UAtomic oxygen radical anion (O- ) is one of the most active oxygen species, and has extremely high oxidation ability toward small-molecules of hydrocarbons. However, to our knowledge, little is known about the effects of O- on cells of micro-organisms. This work showed that O- could quickly react with the Bacillus subtilis cells and seriously damage the cell walls a s well as their other contents, leading to a fast and irreversible inactivation. SEM micrographs revealed that the cell structures were dramatically destroyed by their exposure to O-. The inactivation efficiencies of B. subtilis depend on the O-- intensity, the initial population of cells and the treatment temperature, but not on the pH in the range of our investigation. For a cell concentration of 106 cfu/ml, the number of survived cells dropped from 106 cfu/ml to 103 cfu/ml after about five-minute irradiation by an O- flux in an intensity of 233 nA/cm2 under a dry argon environment (30 ℃, 1 atm, exposed size: 1.8 cm2). The inactivation mechanism of micro-organisms induced by O- is also discussed.

  6. Superoxide radical production in chicken skeletal muscle induced by acute heat stress.

    Science.gov (United States)

    Mujahid, A; Yoshiki, Y; Akiba, Y; Toyomizu, M

    2005-02-01

    Heat stress is of major concern for poultry, especially in the hot regions of the world because of the resulting poor growth performance, immunosuppression, and high mortality. To assess superoxide (O2*-) production in mitochondria isolated from skeletal muscle of chickens (n = 4 to 8) exposed to acute heat stress, electron spin resonance (ESR) spectroscopy using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trap agent and lucigenin-derived chemiluminescence (LDCL) method were applied. ESR spectra of suspensions containing mitochondria from control and acute heat-treated meat-type chickens showed similar hyperfine coupling constants (aN = 1.44 mT, aHbeta = 0.12 mT, and aHbeta = 0.11 mT) to those of DMPO-O2*- adducts observed in a hypoxanthine-xanthine oxidase system. Heat exposure resulted in enhancement of the DMPO-O2*- signal. The results using LDCL showed significantly enhanced superoxide production in heat stress-treated skeletal muscle mitochondria of meat-type chickens, whereas no such increase was observed in laying chickens. The enhancement of superoxide production in the former case was associated with heat-induced increments in rectal and muscle temperatures, leading to significant body weight loss. In contrast, the latter case showed no increase in temperatures, although there was a slight decrease in body weight gain. Percentage increases of superoxide production in the presence of carboxyatractylate, a specific inhibitor of adenine nucleotide translocator (ANT), were the same for skeletal muscle mitochondria from meat- and laying-type chickens from the control or heat stress-treated group. This finding suggests the irrelevance of ANT in the regulation of reactive oxygen species flux under heat stress conditions. The study provides the first evidence of superoxide anion production in the skeletal muscle mitochondria of meat-type chickens in response to acute heat stress.

  7. Effect of Mn cluster on the formation of superoxide radicals in photoinhibition of photosystem Ⅱ

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To further realize the action of superoxide radicals (O-2) in photoinhibition of photosystem Ⅱ (PS Ⅱ),we employed 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trap, associated with EPR spectroscopy, to study the effect of illumination time on O-*2 formation during high light photoinhibition in PS Ⅱ membranes and Mn-depleted PS Ⅱ membranes. Results indicated that the removal of Mn cluster from PSⅡmembranes has a strong influence on the dynamnics of superoxide formation.The relative mechanism was also discussed.These novel findings may further promote the studies of the structure and function of PSⅡand the mechanism of photoinhibition.

  8. Using Distonic Radical Ions to Probe the Chemistry of Key Combustion Intermediates: The Case of the Benzoxyl Radical Anion

    Science.gov (United States)

    Li, Cong; Lam, Adrian K. Y.; Khairallah, George N.; White, Jonathan M.; O'Hair, Richard A. J.; da Silva, Gabriel

    2013-04-01

    The benzoxyl radical is a key intermediate in the combustion of toluene and other aromatic hydrocarbons, yet relatively little experimental work has been performed on this species. Here, a combination of electrospray ionization (ESI), multistage mass spectrometry experiments, and density functional theory (DFT) calculations are used to examine the formation and fragmentation of a benzoxyl (benzyloxyl) distonic radical anion. Excited 4-carboxylatobenzoxyl radical anions were produced via two methods: (1) collision induced dissociation (CID) of the nitrate ester 4-(nitrooxymethyl)benzoate, -O2CC6H4CH2ONO2, and (2) reaction of ozone with the 4-carboxylatobenzyl radical anion, -O2CC6H4CH2 •. In neither case was the stabilized -O2CC6H4CH2O• radical anion intermediate detected. Instead, dissociation products at m/ z 121 and 149 were observed. These products are attributed to benzaldehyde (O2 -CC6H4CHO) and benzene (-O2CC6H5) products from respective loss of H and HCO radicals in the vibrationally excited benzoxyl intermediate. In no experiments was a product at m/ z 120 (i.e., -O2CC6H4 •) detected, corresponding to absence of the commonly assumed phenyl radical + CH2=O channel. The results reported suggest that distonic ions are useful surrogates for reactive intermediates formed in combustion chemistry.

  9. Formation and disappearance of superoxide radicals in aqueous solutions. [79 references

    Energy Technology Data Exchange (ETDEWEB)

    Allen, A O; Bielski, B H.J.

    1980-01-01

    A literature review of superoxide radicals in aqueous solutions is presented covering the following: history; methods of formation of aqueous HO/sub 2//HO/sub 2//sup -/ by radiolysis and photolysis, electrolysis, mixing nonaqueous solutions into water, chemical reactions, enzymatic generation of O/sub 2//sup -/, and photosensitization; and properties of HO/sub 2//O/sub 2//sup -/ in aqueous solution, which cover spontaneous dismutation rates, pk and absorption spectra, catalyzed dismutation, thermodynamics and the so-called Haber-Weiss Reaction.

  10. Pyrroloquinoline quinone from Gluconobacter oxydans fermentation broth enhances superoxide anion-scavenging capacity of Cu/Zn-SOD.

    Science.gov (United States)

    Ma, Ke; Cui, Jun-Zhu; Ye, Jian-Bin; Hu, Xian-Mei; Ma, Ge-Li; Yang, Xue-Peng

    2017-09-01

    A bioassay-guided fractionation of extract from Gluconobacter oxydans fermentation broth afforded Compound 1, which was identified as pyrroloquinoline quinone (PQQ) by spectroscopic methods. PQQ has been shown to enhance the superoxide anion-scavenging capacity significantly for Cu/Zn-SOD. To illustrate the mechanism, the interaction between PQQ and Cu/Zn-SOD was investigated. The multiple binding sites involving hydrogen bonds and van der Waals force between PQQ and Cu/Zn-SOD were revealed by isothermal titration calorimetry. The α-helix content was increased in the Cu/Zn-SOD structure with the addition of PQQ into the solution through ultraviolet (UV) spectroscopy. These results indicated that PQQ could change the conformation of Cu/Zn-SOD through interaction, which could enhance its superoxide anion-scavenging capacity. Therefore, PQQ is a potential natural antioxidant. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. The changes of serum nitric oxide, angiotensin Ⅱ and superoxide anion in renal artery hypertension rat

    Institute of Scientific and Technical Information of China (English)

    马向红; 杨万松; 黄体钢; 周丽娟; 倪燕平; 樊振旺

    2003-01-01

    Objectives To study the changes of nitric oxide, angiotensin Ⅱ and superoxide anion in renal artery hypertension pathogenesis. Methods Male Wistar rats weighing 256 -285g were divided into 5 groups randomly, 10 rats of each group. Control group:false operation was made and routine diet was given; Ligature group: left renal artery was ligatured uncompletely and routine diet was given; Ligature + Losartan group:left renal artery was ligatured uncompletely and Losartan ture + L -Arg group: left renal artery was ligatured undrinking water; Ligature + L - Arg + Losartan group: left the drinking water. Blood pressure and heart rate were measured before and at the end of the experiment. One week after ligature, blood was drawn to determine angiotensin Ⅱ, cGMP, nitric oxide, nitric oxide synthase (NOS), O2-, superoxide dismutase (SOD). Results Systolic blood pressure was higher in ligature group than that in control group (p<0.05), systolic blood pressure was much lower in ligature + Losartan group than that in ligature group. Heart rate did not change significantly after experiment (p > 0. 05 ). AngⅡ was higher in ligature group than that in control group, even much higher in ligature + Losartan group (p < 0. 01 ). There was no difference of cGMP in each group (p > 0. 05 ). The concentration of NO was lower in ligature group (p < 0. 05 ), NO was higher in ligature + L - Arg + Losartan group than that in ligature group (p < 0. 05). O2' was higher in ligature group and ligature + L - Arg group than that in control group (p < 0. 05), O2- was lower in ligature + Losartan group than that in ligature group (p <0. 05). The level of SOD was lower in ligature group than that in control group (p < 0.05), higher in ligature + L - Arg group and ligature + L - Arg + Losartan group than that in ligature group (p <0.05). Conclusions AnglⅡ,O2- and NO imbalance play an important role in hypertension pathogenesis, L-Arg and losartan may have protective effect.

  12. OD ESR detection of the radical anions of cyclic nitrones in liquid solutions

    Science.gov (United States)

    Barlukova, M. M.; Gritsan, N. P.; Bagryansky, V. A.; Starichenko, V. F.; Grigor'ev, I. A.; Molin, Yu. N.

    2005-01-01

    The radical anions of five-membered cyclic nitrone spin traps, 3,3,5,5-tetramethyl-1-pyrroline-1-oxide and 1,2,2,5,5-pentamethyl-3-imidazoline-3-oxide, formed under radiolysis of liquid squalane solutions at 250-268 K, were registered by the method of optically detected ESR, and the hfc constants and g-values of the radical anions were determined. The hfc constants of these radical anions were predicted by DFT calculations and were found to be in quantitative agreement with experiment. It was demonstrated that radical anions of the five-membered cyclic nitrones have non-planar geometry with the spin density localized in the C dbnd N sbnd O fragment.

  13. Membrane Separator for Redox Flow Batteries that Utilize Anion Radical Mediators.

    Energy Technology Data Exchange (ETDEWEB)

    Delnick, Frank M.

    2014-10-01

    A Na + ion conducting polyethylene oxide membrane is developed for an organic electrolyte redox flow battery that utilizes anion radical mediators. To achieve high specific ionic conductivity, tetraethyleneglycol dimethylether (TEGDME) is used as a plasticizer to reduce crystallinity and increase the free volume of the gel film. This membrane is physically and chemically stable in TEGDME electrolyte that contains highly reactive biphenyl anion radical mediators.

  14. Modifications in nitric oxide and superoxide anion metabolism induced by fructose overload in rat heart are prevented by (-)-epicatechin.

    Science.gov (United States)

    Calabró, Valeria; Piotrkowski, Barbara; Fischerman, Laura; Vazquez Prieto, Marcela A; Galleano, Monica; Fraga, Cesar G

    2016-04-01

    Fructose overload promotes functional and metabolic derangements in humans and in animal experimental models. Evidence suggests that dietary flavonoids have the ability to prevent/attenuate the development of metabolic diseases. In this work we investigated the effects of (-)-epicatechin on the modifications induced by fructose overload in the rat heart in terms of nitric oxide and superoxide metabolism. Male Sprague Dawley rats received 10% (w/v) fructose in the drinking water for 8 weeks, with or without (-)-epicatechin (20 mg per kg body weight per day) in the rat chow diet. These conditions of fructose overload did not lead to overt manifestations of heart hypertrophy or tissue remodeling. However, biochemical and molecular changes were observed and could represent the onset of functional alterations. (-)-Epicatechin prevented a compromised NO bioavailability and the development of oxidative stress produced by fructose overload essentially acting on superoxide anion metabolism. In this line, the increase in superoxide anion production, the overexpression of NOX2 subunit p47phox and of NOX4, the decrease in superoxide dismutase activity, and the higher oxidized/reduced glutathione ratio installed by fructose overload were absent in the rats receiving (-)-epicatechin. These results support the hypothesis that diets rich in (-)-epicatechin could prevent the onset and progression of heart dysfunctions associated with metabolic alterations.

  15. 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.

  16. Kinetics and mechanism of superoxide radical reactions with some biologically important compounds in aqueous solutions. Pulse radiolysis

    Science.gov (United States)

    Revina, A. A.; Amiragova, M. I.; Volod'ko, V. V.; Vannikov, A. V.

    Microsecond pulse radiolysis of oxygenated aqueous solutions containing 0.02 mol dm -3 sodium formate and 2 mmol dm -3 phosphate buffer at pH 7 was used to generate superoxide anion radicals. The influence of some biologically important compounds upon the rate of O ⨪2 decay was monitored spectrophotometrically in the range of 245-300 nm. Hematoporphyrin (HP), hemin C (HC), catalase (Cat), cobalt sulfophthalocyanine (CoTSPc) were studied. Among the investigated compounds only Cat was found to show a high catalytic efficiency towards the self-decay of O ⨪2. A red shift of O ⨪2 absorption band and slowing down of its decay were observed to take place by adding HP or CoTSPc to the solutions containing formate ions in excess. This effect is associated with the formation of a transient superoxo-complex. An appearance of an intermediate species with absorption maxima at 350 nm and half-life of about 2s was observed to accompany the superoxo-complex of CoTSPc decay. In the aerated solution of HP the intensity of absorbance at 260 nm was found to be independent of the presence of formate ions.

  17. 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.

  18. Qualitative analysis of phytochemicals, and comparative superoxide radical scavenging along with reducing potency of Solanum nigrum using various solvent extracts

    Directory of Open Access Journals (Sweden)

    A Thenmozhi

    2011-01-01

    Full Text Available An attempt has been made to screen the phytochemicals, comparative superoxide radical scavenging and reducing potency of Solanum nigrum using various solvent extracts. The herbal powder obtained from plant part-dry leaves were extracted with various solvents. The extracts were analysed for phytochemicals and antioxidants-carotenoids, ascorbic acid, tocopherol, total phenol, proteins, reducing sugars and sterols. Free radical scavenging capacity was analysed in terms of superoxide radial scavenging assay and reducing power assay. Phytochemical characterization of the different extracts revealed the presence of the phytochemicals-alkaloids, phenols, flavonoids, sterol, saponin glycosides, reducing sugars, proteins, cardio active aglycones and cardinolides. Excellent Superoxide Radical scavenging ability found in almost all extracts of S. nigrum. In the present study superoxide radical reduces nitro blue tetrazolium (NBT to a blue coloured formazan that is measured at 560 nm. Antioxidant activity has been reported to be concomitant with development of reducing power. This shows that extracts might contain reductones like ascorbic acid, reducing sugar, thiol group containing protein which could react with free radicals to stabilize and terminate radical chain reaction. These findings suggest that the promising phytonutrients of the plant could be exploited against oxidative stress, cancer, ageing, Ischemic heart disease in dissolving thrombus, microbial infections and hormone replacement therapy (HRT justifying their use in traditional medicine as nutraceuticals.

  19. The strong influence of the solvent on the electron spin resonance spectra of semiquinone radical anions

    DEFF Research Database (Denmark)

    Spanget-Larsen, Jens

    2013-01-01

    The hyperfine constants of the chrysazin radical anion and the anthralin-10-yl radical were studied by UB3LYP Density Functional Theory (DFT) calculations, using the basis sets EPR-II or EPR-III and representing the influence of the solvent by the Isodensity Polarizable Continuum Model (IPCM......). The proton hyperfine constants predicted for the chrysazin semiquinone radical anion were highly sensitive to the assumed dielectric constant ε of the solvent continuum, inverting the relative magnitudes of the hyperfine constants and thereby leading to agreement with the observed data published by Stegmann...

  20. Reactions between the (SO·4-) radical and some common anions in atmospheric aqueous droplets

    Institute of Scientific and Technical Information of China (English)

    OUYANG Bin; FANG Hao-jie; ZHU Cheng-zhu; DONG Wen-bo; HOU Hui-qi

    2005-01-01

    The rate constants of reactions between the SO4·- radical and some common anions in atmospheric aqueous droplets e.g. Cl-,NO3-, HSO3- and HCO3- were determined using the laser flash photolysis technique. Absorption spectra of SO4·- and the product radicals were also reported. The chloride ion was evaluated among all the anions to be the most efficient scavenger of SO4·- . The results may supply useful information for a better understanding of the vigorous radical-initiated reactions in atmospheric aqueous droplets such as clouds, rains or fogs.

  1. Superoxide anion production and expression of gp91(phox) and p47(phox) are increased in glomeruli and proximal tubules of cisplatin-treated rats.

    Science.gov (United States)

    Trujillo, Joyce; Molina-Jijón, Eduardo; Medina-Campos, Omar Noel; Rodríguez-Muñoz, Rafael; Reyes, José Luis; Barrera, Diana; Pedraza-Chaverri, José

    2015-04-01

    The chemotherapeutic drug cisplatin has some side effects including nephrotoxicity that has been associated with reactive oxygen species production, particularly superoxide anion. The major source of superoxide anion is nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) oxidase. However, the specific segment of the nephron in which superoxide anion is produced has not been identified. Rats were sacrificed 72 h after cisplatin injection (7.5 mg/kg), and kidneys were obtained to isolate glomeruli and proximal and distal tubules. Cisplatin induced superoxide anion production in glomeruli and proximal tubules but not in distal tubules. This enhanced superoxide anion production was prevented by diphenylene iodonium, an inhibitor of NADPH oxidase. Consistently, this effect was associated with the increased expression of gp91(phox) and p47(phox), subunits of NADPH oxidase. The enhanced superoxide anion production in glomeruli and proximal tubules, associated with the increased expression of gp91(phox) and p47(phox), is involved in the oxidative stress in cisplatin-induced nephrotoxicity.

  2. HIV-1-infected monocytes and monocyte-derived macrophages are impaired in their ability to produce superoxide radicals.

    Science.gov (United States)

    Howell, A L; Groveman, D S; Wallace, P K; Fanger, M W

    1997-01-01

    Monocytes and monocyte-derived macrophages play a key role in immune defense against pathogenic organisms. Superoxide anion production is a key mechanism by which phagocytes kill pathogens. We sought to determine whether human immunodeficiency virus-infected monocytes and monocyte-derived macrophages are compromised in their ability to produce the superoxide anion following stimulation with phorbol myristate acetate (PMA) or after cross-linking the type I Fc receptor for IgG (Fc gamma RI). Fc gamma RI was cross-linked by the binding of monoclonal antibody 197, which reacts with an epitope of Fc gamma RI via its Fc region. Monocytes and monocyte-derived macrophages obtained from seronegative donors were infected in vitro with human immunodeficiency virus-1JR-FL and used in effector assays that measured superoxide anion production by the reduction of nitroblue tetrazolium. Reduced nitroblue tetrazolium was measured spectrophotometrically and by microscopy in which the percentage of cells containing intracellular deposits of the dye was assessed. By spectrophotometric measurement, we found that human immunodeficiency virus-infected monocytes and monocyte-derived macrophages produced less superoxide anion following either phorbol myristate acetate stimulation or Fc gamma RI cross-linking than uninfected cells from the same donor. Using microscopy we saw no difference in the percentage of infected and uninfected macrophages containing intracellular deposits of nitroblue tetrazolium suggesting that human immunodeficiency virus-infected macrophages produce less superoxide anion on a per cell basis than uninfected macrophages. Activation of human immunodeficiency virus-infected monocytes with interferon-gamma for 72 h prior to stimulation with phorbol myristate acetate or monoclonal antibody 197 increased their ability to reduce nitroblue tetrazolium. These findings suggest that impairment in the production of reactive oxygen intermediates may, in some cases, contribute to

  3. [Free radicals of oxygen and superoxide dismutase. Biological and medical aspects].

    Science.gov (United States)

    Monte, M; Sacerdote de Lustig, E

    1994-01-01

    Oxygen free radicals (OFR) are very reactive and unstable metabolites capable of altering important biomolecules including proteins, lipids and nucleic acids. OFR are regulated by enzymes such as superoxide dismutases (SOD), catalase, glutation peroxidase and by molecules such as vitamins E, A, C, and K, selenio, cystein and other compounds. Increased OFR levels due to an overproduction of these metabolites or to a failure in the control system, induce cellular and tissue injuries that could lead to diseases such as atherosclerosis, arthritis, fibrosis, lung and heart injuries, neurological disorders and cancer. In this article we consider the use of SOD as therapeutic agents both in human and experimental models. We also refer to the administration of SOD as a protective factor against secondary injuries during radiotherapy and to the determination of SOD as a tumor marker.

  4. Use of high-performance liquid chromatography to detect hydroxyl and superoxide radicals generated from mitomycin C.

    Science.gov (United States)

    Pritsos, C A; Constantinides, P P; Tritton, T R; Heimbrook, D C; Sartorelli, A C

    1985-11-01

    Distinguishing between short-lived reactive oxygen species like hydroxyl and superoxide radicals is difficult; the most successful approaches employ electron spin resonance (ESR) spin-trapping techniques. Using the spin trap 5,5-dimethyl-l-pyrroline N-oxide (DMPO) to selectively trap various radicals in the presence and absence of ethanol, an HPLC system which is capable of separating the hydroxyl- and superoxide-generated DMPO adduct species has been developed. The radical-generated DMPO adducts were measured with an electrochemical detector attached to the HPLC system and confirmed by spin-trapping techniques. The HPLC separation was carried out on an ODS reverse-phase column with a pH 5.1 buffered 8.5% acetonitrile mobile phase. The advantage of the HPLC system described is that it permits the separation and detection of hydroxyl and superoxide radicals without requiring ESR instrumentation. The antineoplastic bioreductive alkylating agent mitomycin C, when activated by NADPH-cytochrome c reductase, was shown to generate both hydroxyl and superoxide radicals.

  5. Possible Involvement of NADPH Oxidase in Lanthanide Cation-Induced Superoxide Anion Generation in BY-2 Tobacco Cell Suspension Culture

    Institute of Scientific and Technical Information of China (English)

    Yang Shengchang

    2006-01-01

    A rapid and concentration-dependent generation of superoxide anion (·O-2), measured with a superoxide-specific Cypridina luciferin-derived chemiluminescent reagent, was observed when two lanthanide salts (LaCl3 and GdCl3) were added to tobacco (Nicotiana tabacum) cell suspension culture.Addition of superoxide dismutase (480 U·ml-1) and Tiron (5 μmol·L-1) to cell culture suspension decreases the level of lanthanide cation-induced ·O-2 generation, suggesting that ·O-2 generation is extra-cellular.Pretreatment of the cell culture suspension with diphenyleneiodonium (10 and 50 μmol·L-1), quinacrine (1 and 5 mmol·L-1) and imidazol (10 mmol·L-1), inhibitors of NADPH oxidase, notably inhibits the generation of superoxide induced by lanthanide cation, implying the possible involvement of activation of NADPH oxidase.In addition, addition of SHAM (1 and 5 mmol·L-1), azide (0.2 and 1 mmol·L-1), inhibitor of peroxidase, has no influence on ·O-2 generation.

  6. Propylparaben-induced disruption of energy metabolism in human HepG2 cell line leads to increased synthesis of superoxide anions and apoptosis.

    Science.gov (United States)

    Szeląg, S; Zabłocka, A; Trzeciak, K; Drozd, A; Baranowska-Bosiacka, I; Kolasa, A; Goschorska, M; Chlubek, D; Gutowska, I

    2016-03-01

    The effect of propylparaben (in final concentrations 0.4 ng/ml, 2.3 ng/ml and 4.6 ng/ml) on the energy metabolism of HepG2 hepatocytes, superoxide anion synthesis, apoptosis and necrosis is described. Propylparaben can be toxic to liver cells due to the increased production of superoxide anions, which can contribute to a reduced concentration of superoxide dismutase in vivo and impairment of the body's antioxidant mechanisms. Finally, a further reduction in the mitochondrial membrane potential and uncoupling of the respiratory chain resulting in a reduction in ATP concentration as a result of mitochondrial damage may lead to cell death by apoptosis.

  7. Electron affinities of aromatic hydrocarbons and disproportionation of their radical-anions

    Energy Technology Data Exchange (ETDEWEB)

    Szwarc, M.

    1986-09-01

    Electron affinities of aromatic hydrocarbons measured in the gas-phase and in solutions are compared. The experimental methods used for their determination are briefly reviewed. The reduction yields the respective radical-anions. Radical-anions may undergo disproportionation, a reaction described by the scheme: 2A/sup -/ . , Cat/sup =/ in equilibrium A + A/sup 2-/, 2 Cat/sup +/, K/sub dipr/. The disproportionation constant, K/sub dipr/, is greatly affected by the nature of aromatic hydrocarbon, of the cation, and of the solvent. Variation of each of these factors is illustrated. Variation of the cation and solvent results in changes of the disproportionation constant as large as factors of 10/sup 25/. The causes of these variations are rationalized and discussed in terms of the respective ..delta..H and ..delta..S. Kinetics of disproportionation was investigated by flash-photolysis techniques. The experimental approach is described. The peculiarities of Ba salts deserved some discussion to clarify the nature of those salts. The effect of disproportionation on reactions of radical-anions are described: namely on cis-trans isomerization of stilbenes, on protonation of radical-anions of anthracene an perylene, on dissociation of radical anions of aromatic derivatives ethane, etc.

  8. Effects of PDE4 inhibitors on lipopolysaccharide-induced priming of superoxide anion production from human mononuclear cells

    Directory of Open Access Journals (Sweden)

    Noëlla Germain

    2001-01-01

    Full Text Available Aims: Phosphodiesterase 4 (PDE4 inhibitors have been described as potent anti-inflammatory compounds, involving an increase in intracellular levels of cyclic 3',5'-adenosine monophosphate (AMP. The aim of this study was to compare the effects of selective PDE4 inhibitors, rolipram and RP 73-401 with the cell permeable analogue of cyclic AMP, dibutyryl-cyclic AMP (db-cAMP and the anti-inflammatory cytokine interleukin-10 (IL-10 on superoxide anion production from peripheral blood mononuclear cells preincubated with lipopolysaccharide (LPS.

  9. Photocatalytic degradation kinetics and mechanism of pentachlorophenol based on superoxide radicals

    Institute of Scientific and Technical Information of China (English)

    Yang Li; Junfeng Niu; Lifeng Yin; Wenlong Wang; Yueping Bao; Jing Chen; Yanpei Duan

    2011-01-01

    The micron grade multi-metal oxide bismuth silicate (Bi12SiO20,BSO) was prepared by the chemical solution decomposition technique.Photocatalytic degradation of pentachlorophenol (PCP) was investigated in the presence of BSO under xenon lamp irradiation.The reaction kinetics followed pseudo first-order and the degradation ratio achieved 99.1% after 120 min at an initial PCP concentration of 2.0 mg/L.The pH decreased from 6.2 to 4.6 and the dechlorination ratio was 68.4% after 120 min at an initial PCP concentration of 8.0 mg/L.The results of electron spin resonance showed that superoxide radical (O2-) was largely responsible for the photocatalytic degradation of PCP.Interestingly,this result was different from that of previous photocatalytic reactions where valence band holes or hydroxyl radicals played the role of major oxidants.Some aromatic compounds and aliphatic carboxylic acids were determined by GC/MS as the reaction intermediates,which indicated that O2- can attack the bond between the carbon and chlorine atoms to form less chlorinated aromatic compounds.The aromatic compounds were further oxidized by O2- to generate aliphatic carboxylic acids which can be finally mineralized to CO2 and H2O.

  10. Effect of xenobiotics on the respiratory activity of rat heart mitochondria and the concomitant formation of superoxide radicals

    Energy Technology Data Exchange (ETDEWEB)

    Stolze, K.; Nohl, H. (Univ. of Vienna (Austria). Inst. of Pharmacology and Toxicology)

    1994-03-01

    The effects of the xenobiotics atrazine, benzene, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), lindane, toluene, and xylenol on the respiration of isolated rate heart mitochondria were studied. Bioenergetic parameters such as respiratory control (RC) and ATP/oxygen (P/O) values decreased considerably in the presence of these substances, and a concomitant increase of superoxide radical (O[sub 2][sup [minus

  11. Preparation of (±)-5,6,7-Trioxygenated Dihydrofiavonols and Evaluation of their Superoxide Radical Scavenging Activity

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The synthesis of (±)-5, 6, 7-trioxygenated dihydroflavonols was carried out. All synthetic compounds were passed through superoxide radical scavenging activity in vitro.Compounds 1 e and 1 g exhibited significant bioactivity with the inhibitory rates of 68.1% and 80.9% at 40 μg/mL, respectively.

  12. Formation of radical anions of radiosensitizers and related model compounds via electrospray ionization

    DEFF Research Database (Denmark)

    Feketeová, Linda; Albright, Abigail L; Sørensen, Brita Singers

    2014-01-01

    Radiosensitizers are used in radiotherapy to enhance tumour control of radioresistant hypoxic tumours. While the detailed mechanism of radiosensitization is still unknown, the formation of radical anions is believed to be a key step. Thus understanding the ionization reactions of radiosensitizers......, misonidazole and related compounds using a hybrid linear ion trap – Fourier Transform Ion Cyclotron Resonance mass spectrometer (Finnigan-LTQ-FT). A key finding is that negative electrospray ionization of these radiosensitizers leads to the formation of radical anions, allowing their fragmentation reactions...

  13. Long-range intramolecular electron transfer in aromatic radical anions and binuclear transition metal complexes

    DEFF Research Database (Denmark)

    Kuznetsov, A. M.; Ulstrup, Jens

    1981-01-01

    Intramolecular electron transfer (ET) over distances up to about 10 Å between states in which the electron is localized on donor and acceptor groups by interaction with molecular or external solvent nuclear motion occurs, in particular, in two classes of systems. The excess electron in anionic...... in the intermediate states. We have furthermore provided criteria for the distinction between direct ET, ET through high-energy (superexchange), and low-energy (''radical'' intermediate mechanism) intermediate states on the basis of experimental rate data and illustrated this with data for organic radical anions...

  14. Resonance Raman Spectrum of the Transient (SCN)2 Free Radical Anion

    DEFF Research Database (Denmark)

    Wilbrandt, Robert Walter; Jensen, N. H.; Pagsberg, Palle Bjørn

    1979-01-01

    The resonance Raman spectrum of the transient species (λmax = 475 nm, τ½ = 1.6 μs) formed by pulse radiolysis of aqueous solutions of thiocyanate, SCN2−, is reported. The spectrum is discussed in terms of the previous assignment of this transient to the radical anion, (SCN)−2. The observed...... vibrational frequencies of the radical anion are consistent with substantial weakening of the S---S and the Ctriple bond; length as m-dashN bonds are compared with neutral thiocyanogen....

  15. 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 Cα-C bond but also stimulates the breaking of N-Cα 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-Cα 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 ππ* and repulsive πσ* excited states of a model amide system.

  16. Superoxide anions produced by Streptococcus pyogenes group A-stimulated keratinocytes are responsible for cellular necrosis and bacterial growth inhibition.

    Science.gov (United States)

    Regnier, Elodie; Grange, Philippe A; Ollagnier, Guillaume; Crickx, Etienne; Elie, Laetitia; Chouzenoux, Sandrine; Weill, Bernard; Plainvert, Céline; Poyart, Claire; Batteux, Frédéric; Dupin, Nicolas

    2016-02-01

    Gram-positive Streptococcus pyogenes (group A Streptococcus or GAS) is a major skin pathogen and interacts with keratinocytes in cutaneous tissues. GAS can cause diverse suppurative and inflammatory infections, such as cellulitis, a common acute bacterial dermo-hypodermitis with a high morbidity. Bacterial isolation yields from the lesions are low despite the strong local inflammation observed, raising numerous questions about the pathogenesis of the infection. Using an in vitro model of GAS-infected keratinocytes, we show that the major ROS produced is the superoxide anion ([Formula: see text]), and that its production is time- and dose-dependent. Using specific modulators of ROS production, we show that [Formula: see text] is mainly synthesized by the cytoplasmic NADPH oxidase. Superoxide anion production leads to keratinocyte necrosis but incomplete inhibition of GAS growth, suggesting that GAS may be partially resistant to the oxidative burst. In conclusion, GAS-stimulated keratinocytes are able to develop an innate immune response based on the production of ROS. This local immune response limits GAS development and induces keratinocyte cell death, resulting in the skin lesions observed in patients with cellulitis.

  17. Stochastic modelling suggests that an elevated superoxide anion - hydrogen peroxide ratio can drive extravascular phagocyte transmigration by lamellipodium formation.

    Science.gov (United States)

    Kundu, Siddhartha

    2016-10-21

    Chemotaxis, integrates diverse intra- and inter-cellular molecular processes into a purposeful patho-physiological response; the operatic rules of which, remain speculative. Here, I surmise, that superoxide anion induced directional motility, in a responding cell, results from a quasi pathway between the stimulus, surrounding interstitium, and its biochemical repertoire. The epochal event in the mounting of an inflammatory response, is the extravascular transmigration of a phagocyte competent cell towards the site of injury, secondary to the development of a lamellipodium. This stochastic-to-markovian process conversion, is initiated by the cytosolic-ROS of the damaged cell, but is maintained by the inverse association of a de novo generated pool of self-sustaining superoxide anions and sub-critical hydrogen peroxide levels. Whilst, the exponential rise of O2(.-) is secondary to the focal accumulation of higher order lipid raft-Rac1/2-actin oligomers; O2(.-) mediated inactivation and redistribution of ECSOD, accounts for the minimal concentration of H2O2 that the phagocyte experiences. The net result of this reciprocal association between ROS/ RNS members, is the prolonged perturbation and remodeling of the cytoskeleton and plasma membrane, a prelude to chemotactic migration. The manuscript also describes the significance of stochastic modeling, in the testing of plausible molecular hypotheses of observable phenomena in complex biological systems.

  18. Antioxidant protection of NO-induced relaxations of the mouse anococcygeus against inhibition by superoxide anions, hydroquinone and carboxy-PTIO.

    Science.gov (United States)

    Lilley, E; Gibson, A

    1996-09-01

    physiological antioxidants protected NO from superoxide anions, and from direct NO-scavengers. The possibility that the presence of these antioxidants within nitrergically-innervated tissues might explain the lack of effect of the NO inhibitors on nerve-induced relaxation, without the need to invoke a transmitter other than free radical NO, is discussed.

  19. A superoxide anion-scavenger, 1,3-selenazolidin-4-one suppresses serum deprivation-induced apoptosis in PC12 cells by activating MAP kinase

    Energy Technology Data Exchange (ETDEWEB)

    Nishina, Atsuyoshi, E-mail: nishina@yone.ac.jp [Yonezawa Women' s Junior College, 6-15-1 Tohrimachi, Yonezawa, Yamagata 992-0025 (Japan); Kimura, Hirokazu; Kozawa, Kunihisa [Gunma Prefectural Institute of Public Health and Environmental Sciences, 378 Kamioki, Maebashi, Gunma 371-0052 (Japan); Sommen, Geoffroy [Lonza Braine SA, Chaussee de Tubize 297, B-1420 Braine l' Alleud (Belgium); Nakamura, Takao [Department of Biomedical Information Engineering, Graduate School of Medical Science, Yamagata University, Yamagata 990-9585 (Japan); Heimgartner, Heinz [University of Zuerich, Institut of Organic Chemistry, Winterthurerstrasse 190, CH-8057 Zuerich (Switzerland); Koketsu, Mamoru [Department of Materials Science and Technology, Faculty of Engineering, Gifu University, Gifu 501-1193 (Japan); Furukawa, Shoei [Laboratory of Molecular Biology, Gifu Pharmaceutical University, 5-6-1 Mitahora-higashi, Gifu 502-8585 (Japan)

    2011-12-15

    Synthetic organic selenium compounds, such as ebselen, may show glutathione peroxidase-like antioxidant activity and have a neurotrophic effect. We synthesized 1,3-selenazolidin-4-ones, new types of synthetic organic selenium compounds (five-member ring compounds), to study their possible applications as antioxidants or neurotrophic-like molecules. Their superoxide radical scavenging effects were assessed using the quantitative, highly sensitive method of real-time kinetic chemiluminescence. At 166 {mu}M, the O{sub 2}{sup -} scavenging activity of 1,3-selenazolidin-4-ones ranged from 0 to 66.2%. 2-[3-(4-Methoxyphenyl)-4-oxo-1,3-selenazolidin-2-ylidene]malononitrile (compound b) showed the strongest superoxide anion-scavenging activity among the 6 kinds of 2-methylene-1,3-selenazolidin-4-ones examined. Compound b had a 50% inhibitory concentration (IC{sub 50}) at 92.4 {mu}M and acted as an effective and potentially useful O{sub 2}{sup -} scavenger in vitro. The effect of compound b on rat pheochromocytome cell line PC12 cells was compared with that of ebselen or nerve growth factor (NGF) by use of the MTT [3-(4, 5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide] assay. When ebselen was added at 100 {mu}M or more, toxicity toward PC12 cells was evident. On the contrary, compound b suppressed serum deprivation-induced apoptosis in PC12 cells more effectively at a concentration of 100 {mu}M. The activity of compound b to phosphorylate mitogen-activated protein kinase/extracellular signal-regulated protein kinase (ERK) 1/2 (MAP kinase) in PC12 cells was higher than that of ebselen, and the former at 100 {mu}M induced the phosphorylation of MAP kinase to a degree similar to that induced by NGF. From these results, we conclude that this superoxide anion-scavenger, compound b, suppressed serum deprivation-induced apoptosis by promoting the phosphorylation of MAP kinase. -- Highlights: Black-Right-Pointing-Pointer We newly synthesized 1,3-selenazolidin-4-ones to

  20. Copper-zinc alloy nanoparticle based enzyme-free superoxide radical sensing on a screen-printed electrode.

    Science.gov (United States)

    Derkus, Burak; Emregul, Emel; Emregul, Kaan C

    2015-03-01

    In this paper, amperometric enzyme-free sensors using superoxide dismutase (SOD) enzyme as a catalyst for the dismutation reaction of superoxides into oxygen and hydrogen peroxide, enabling superoxide radical detection have been described. For this purpose, the surfaces of screen-printed platinum electrodes have been modified with gelatin composites of CuO, ZnO and CuZn nanoparticles with the expectation of an increase in catalytic effect toward the dismutation reaction. SOD containing electrodes were also prepared for comparative studies in which glutaraldehyde was used as a cross-linker for the immobilization of SOD to the nanocomposite materials. Electrochemical measurements were carried out using a screen-printed electrochemical system that included potassiumferrocyanide (K4[Fe(CN)6]) and potassiumferricyanide (K3[Fe(CN)6]) as the redox probes. The results revealed that the enzyme-free detection method using CuZn nanoparticles can determine superoxide radicals with high performance compared to other detection methods prepared with different nanoparticles by mimicking the active region of superoxide dismutase enzyme. The anodic (ks(a)) and cathodic (ks(c)) electron transfer rate constants and the anodic (α(a)) and cathodic (α(c)) transfer coefficients were evaluated and found to be ks(a)=6.31 s(-1) and α(a)=0.81, ks(c)=1.48 s(-1) and α(c)=0.19 for the gelatin-CuZn-SOD electrode; ks(a)=6.15 s(-1) and α(a)=0.79, ks(c)=1,63 s(-1) and α(c)=0.21 for the enzyme-free gelatin-CuZn electrode. The enzyme-free electrode showed nearly 80% amperometric performance with respect to the enzyme containing electrode indicating the superior functionality of enzyme-free electrode for the detection of superoxide radicals.

  1. Resonance Raman Spectra of the Transient Cl2 and Br2 Radical Anions

    DEFF Research Database (Denmark)

    Wilbrandt, Robert Walter; Jensen, Niels-Henrik; Sillesen, Alfred Hegaard

    1984-01-01

    The resonance Raman spectra of the short-lived radical anions ClImage 2− and BrImage − in aqueous solution are reported. The observed wavenumbers of 279 cm−1 for ClImage − and 177 cm−1 for BrImage − are about 10% higher than those published for the corresponding species isolated in solid argon...

  2. Spectroscopically resolved competition between dissociation and detachment from nitrobenzene radical anion

    NARCIS (Netherlands)

    Steill, J. D.; Oomens, J.

    2011-01-01

    We report the vibrational spectrum of the gas-phase isolated nitrobenzene radical anion. The spectrum has been acquired by infrared multiple-photon absorption induced dissociation and electron detachment using the FT mass spectrometer coupled to the infrared free-electron laser FELIX. Upon wavelengt

  3. Effects of zinc acexamate (NAS-501) on superoxide radicals and lipid peroxidation of rat gastric mucosa.

    Science.gov (United States)

    Tsutsui, Y; Nakamura, Y; Yamaguchi, S; Kawanaka, N; Sato, M

    1999-04-01

    Zinc acexamate (NAS-501), an anti-ulcer agent, has been reported to prevent various acute experimental gastric mucosal lesions and duodenal ulcers in rats. In order to clarify the mechanisms by which NAS-501 exhibits the anti-ulcer effects, we investigated the anti-oxidative effects of NAS-501 in vitro and in vivo. NAS-501 significantly reduced the superoxide radical-dependent chemiluminescence, generated by hypoxanthine-xanthine oxidase, rat neutrophils and guinea-pig macrophages in vitro. These in vitro effects were also confirmed by electron spin resonance using a 5, 5-dimethyl-1-pyrroline-N-oxide spin-trapping method. In addition, NAS-501 significantly inhibited lipid peroxidation induced by increasing concentrations of Fe2+/ascorbate in rat gastric mucosal homogenate in vitro. Oral administration of NAS-501 (30 mg/kg) significantly inhibited production of thiobarbituric acid-reactive substance in rat gastric mucosa following per os instillation of 60% ethanol in 150 mmol/l HCl in vivo. These results suggest that NAS-501 exhibits the preventive effect from acute gastric mucosal lesions by the anti-oxidative activity.

  4. [Role of free radicals on canine bile-induced pancreatitis and effect of superoxide dismutase].

    Science.gov (United States)

    Sato, T

    1995-06-01

    The purpose of this study was to determine the effect of superoxide dismutase (SOD) on canine experimental pancreatitis. Pancreatitis was induced by retrograde biliary juice injection (0.5 ml/kg) to accessory pancreatic duct. Twenty-one mongrel dogs were divided into two groups, i.e. control (untreated) group (n = 13) and SOD-treated group (n = 8). In SOD-treated group, SOD 5000 units/kg was administered from celiac artery immediately after onset of pancreatitis. Xanthine oxidase (XOD), malondialdehyde (MDA), phospholipase (PL), and SOD were assayed from pancreatic tissue 1 and 3 hours after onset of pancreatitis. Serum amylase, elastase I, calcium, and WBC were assayed for 7 days after onset of pancreatitis. XOD and MDA levels were increased in untreated group, and not significantly changed in treated group with statistical difference. PL levels were increased after onset of pancreatitis in both groups and SOD levels were not changed even in treated group. No statistical difference was seen in PL and SOD levels between two groups. Increase of XOD levels suggests continuous generating of free radical species from pancreatic tissue, and SOD inhibits this increase. Increase of PL level was not improved by SOD. Serum laboratory findings and survival rates were not improved by SOD treatment.

  5. Superoxide radical production and performance index of Photosystem II in leaves from magnetoprimed soybean seeds.

    Science.gov (United States)

    Baby, Shine Madukakkuzhyil; Narayanaswamy, Guruprasad Kadur; Anand, Anjali

    2011-11-01

    Priming of soybean seeds with static magnetic field exposure of 200 mT (1 h) and 150 mT (1 h) resulted in plants with enhanced performance index (PI). The three components of PI i.e the density of reaction centers in the chlorophyll bed (RC/ABS), exciton trapped per photon absorbed (φpo) and efficiency with which a trapped exciton can move in electron transport chain (Ψo) were found to be 17%, 27% and 16% higher, respectively in leaves from 200 mT (1h) treated compared to untreated seeds. EPR spectrum of O2.--PBN adduct revealed that the O2.-radical level was lower by 16% in the leaves of plants that emerged from magnetic field treatment. Our study revealed that magnetoprimed seeds have a long lasting stimulatory effect on plants as reduced superoxide production and higher performance index contributed to higher efficiency of light harvesting that consequently increased biomass in plants that emerged from magnetoprimed seeds.

  6. Study on superoxide and hydroxyl radicals generated in indirect electrochemical oxidation by chemiluminescence and UV-visible spectra

    Institute of Scientific and Technical Information of China (English)

    Zhang Botao; Zhao Lixia; Lin Jinming

    2008-01-01

    The generation and transformation of radicals on the cathode of indirect electrochemical oxidation were studied by chemiluminescence (CL) and UV-visible spectra in the reactor with a salt bridge that connected the separated chambers. The CL intensity of 4 × 10-9 mol/L luminol on the cathode with bubbling oxygen was about seven times that of the intensity without it, which was because of the generation of reactive oxygen species (ROS). The existence of ROS, especially the generation of the superoxide radical, could be affirmed by the fact that the CL intensity of 4 × 10--9 mol/L 2-methyl-6-(4-methoxyphenyl)-3,7-dihydroimidazo[1,2-a]pyrazin-3-one with bubbling oxygen was about four times that of the intensity without it. However, there was no chemiluminescence on the anode under the same condition. The change in the UV-visible spectra of nitro blue tetrazolium and N,N-dimethyl-4-nitrosoaniline at the cathode chamber affirmed the transformation from oxygen to superoxide and hydroxyl radicals. The mechanism of the superoxide and hydroxyl radical generation and transformation on the cathode was discussed with the help of the experimental results and relative references.

  7. Vascular nitric oxide and superoxide anion contribute to sex-specific programmed cardiovascular physiology in mice.

    Science.gov (United States)

    Roghair, Robert D; Segar, Jeffrey L; Volk, Kenneth A; Chapleau, Mark W; Dallas, Lindsay M; Sorenson, Anna R; Scholz, Thomas D; Lamb, Fred S

    2009-03-01

    Intrauterine environmental pertubations have been linked to the development of adult hypertension. We sought to evaluate the interrelated roles of sex, nitric oxide, and reactive oxygen species (ROS) in programmed cardiovascular disease. Programming was induced in mice by maternal dietary intervention (DI; partial substitution of protein with carbohydrates and fat) or carbenoxolone administration (CX, to increase fetal glucocorticoid exposure). Adult blood pressure and locomotor activity were recorded by radiotelemetry at baseline, after a week of high salt, and after a week of high salt plus nitric oxide synthase inhibition (by l-NAME). In male offspring, DI or CX programmed an elevation in blood pressure that was exacerbated by N(omega)-nitro-l-arginine methyl ester administration, but not high salt alone. Mesenteric resistance vessels from DI male offspring displayed impaired vasorelaxation to ACh and nitroprusside, which was blocked by catalase and superoxide dismutase. CX-exposed females were normotensive, while DI females had nitric oxide synthase-dependent hypotension and enhanced mesenteric dilation. Despite the disparate cardiovascular phenotypes, both male and female DI offspring displayed increases in locomotor activity and aortic superoxide production. Despite dissimilar blood pressures, DI and CX-exposed females had reductions in cardiac baroreflex sensitivity. In conclusion, both maternal malnutrition and fetal glucocorticoid exposure program increases in arterial pressure in male but not female offspring. While maternal DI increased both superoxide-mediated vasoconstriction and nitric oxide mediated vasodilation, the balance of these factors favored the development of hypertension in males and hypotension in females.

  8. Depression of alveolar macrophage hydrogen peroxide and superoxide anion release by mineral dusts: correlation with antimony, lead, and arsenic contents.

    Science.gov (United States)

    Gulyas, H; Labedzka, M; Gercken, G

    1990-04-01

    Activated rabbit alveolar macrophages were incubated with airborne dusts from four West German sites (1 to 200 micrograms/10(6) cells) and waste incinerator fly ash fractions (50 to 500 micrograms/10(6) cells). Quartz dust DQ 12 (5 to 200 micrograms/10(6) cells) and Fe2O3 (0.05 to 50 micrograms/10(6) cells) were used as control dusts. The zymosan-stimulated hydrogen peroxide and superoxide anion release of the macrophages were not affected significantly by Fe2O3. All other investigated dusts decreased the two cell functions which were correlated negatively with surfaces, particle numbers, and antimony, lead, and arsenic contents of the dusts. The influence of heavy metal antagonisms and dust surfaces on dust toxicity against alveolar macrophages is discussed.

  9. A novel amperometric biosensor for superoxide anion based on superoxide dismutase immobilized on gold nanoparticle-chitosan-ionic liquid biocomposite film

    Energy Technology Data Exchange (ETDEWEB)

    Wang Lu; Wen Wei; Xiong Huayu; Zhang Xiuhua; Gu Haoshuang [Ministry of Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules and College of Chemistry and Chemical Engineering, Hubei University, Wuhan 430062 (China); Wang Shengfu, E-mail: wangsf@hubu.edu.cn [Ministry of Education Key Laboratory for the Synthesis and Application of Organic Functional Molecules and College of Chemistry and Chemical Engineering, Hubei University, Wuhan 430062 (China)

    2013-01-03

    Graphical abstract: Schematic representation of the assembly process of SOD/GNPs-CS-IL/GCE. Highlights: Black-Right-Pointing-Pointer SOD was immobilized in gold nanoparticles-chitosan-ionic liquid (GNPs-CS-IL) film. Black-Right-Pointing-Pointer The biosensor was constructed by one-step ultrasonic electrodeposition of GNPs-CS-IL onto GCE. Black-Right-Pointing-Pointer The biosensor showed excellent analytical performance for O{sub 2}{center_dot}{sup -} real-time analysis. - Abstract: A novel superoxide anion (O{sub 2}{center_dot}{sup -}) biosensor is proposed based on the immobilization of copper-zinc superoxide dismutase (SOD) in a gold nanoparticle-chitosan-ionic liquid (GNPs-CS-IL) biocomposite film. The SOD-based biosensor was constructed by one-step ultrasonic electrodeposition of GNP-CS-IL composite onto glassy carbon electrode (GCE), followed by immobilization of SOD on the modified electrode. Surface morphologies of a set of representative films were characterized by scanning electron microscopy. The electrochemical performance of the biosensor was evaluated by cyclic voltammetry and chronoamperometry. A pair of quasi-reversible redox peaks of SOD with a formal potential of 0.257 V was observed at SOD/GNPs-CS-IL/GCE in phosphate buffer solution (PBS, 0.1 M, pH 7.0). The effects of varying test conditions on the electrochemical behavior of the biosensor were investigated. Furthermore, several electrochemical parameters were calculated in detail. Based on the biomolecule recognition of the specific reactivity of SOD toward O{sub 2}{center_dot}{sup -}, the developed biosensor exhibited a fast amperometric response (<5 s), wide linear range (5.6-2.7 Multiplication-Sign 10{sup 3} nM), low detection limit (1.7 nM), and excellent selectivity for the real-time measurement of O{sub 2}{center_dot}{sup -}. The proposed method is promising for estimating quantitatively the dynamic changes of O{sub 2}{center_dot}{sup -} in biological systems.

  10. FITC Doped Rattle-Type Silica Colloidal Particle-Based Ratiometric Fluorescent Sensor for Biosensing and Imaging of Superoxide Anion.

    Science.gov (United States)

    Zhou, Ying; Ding, Jie; Liang, Tingxizi; Abdel-Halim, E S; Jiang, Liping; Zhu, Jun-Jie

    2016-03-01

    Fluorescent nanosensors have been widely applied in recognition and imaging of bioactive small molecules; however, the complicated surface modification process and background interference limit their applications in practical biological samples. Here, a simple, universal method was developed for ratiometric fluorescent determination of general small molecules. Taking superoxide anion (O2(•-)) as an example, the designed sensor was composed of three main moieties: probe carrier, rattle-type silica colloidal particles (mSiO2@hmSiO2 NPs); reference fluorophore doped into the core of NPs, fluorescein isothiocyanate (FITC); fluorescent probe for superoxide anion, hydroethidine (HE). In the absence of O2(•-), the sensor just emitted green fluorescence of FITC at 518 nm. When released HE was oxidized by O2(•-), the oxidation product exhibited red fluorescence at 570 nm and the intensity was linearly associated with the concentration of O2(•-), while that of reference element remained constant. Accordingly, ratiometric determination of O2(•-) was sensitively and selectively achieved with a linear range of 0.2-20 μM, and the detection limit was calculated as low as 80 nM. Besides, the technique was also successfully applied for dual-emission imaging of O2(•-) in live cells and realized visual recognition with obvious fluorescence color change in normal conditions or under oxidative stress. As long as appropriate reference dyes and sensing probes are selected, ratiometric biosensing and imaging of bioactive small molecules would be achieved. Therefore, the design could provide a simple, accurate, universal platform for biological applications.

  11. Oxidation of caffeine by phosphate radical anion in aqueous solution under anoxic conditions

    Indian Academy of Sciences (India)

    Maram Ravi Kumar; Mundra Adinarayana

    2000-10-01

    The photooxidation of caffeine in presence of peroxydiphosphate (PDP) in aqueous solution at natural H (∼7 5) has been carried out in a quantum yield reactor using a high-pressure mercury lamp. The reactions were followed spectrophotometrically by measuring the absorbance of caffeine at max (272 nm). The rates of reaction were calculated under different experimental conditions. The quantum yields were calculated from the rates of oxidation of caffeine and the intensity of light at 254 nm which was measured by using peroxydisulphate solution as a standard chemical actinometer. The reaction rates of oxidation of caffeine by PDP increase with increase in [PDP] as well as with increase in light intensity, while they are independent of [caffeine]. The quantum yields of oxidation of caffeine by PDP are independent of [PDP] as well as light intensity. However, quantum yields of oxidation of caffeine by PDP increase with increase in caffeine concentration. On the basis of these experimental results and product analysis, a probable mechanism has been suggested in which PDP is activated to phosphate radical anions (PO$_{4}^{\\bullet 2-}$) by direct photolysis of PDP and also by the sensitizing effect of caffeine. The phosphate radical anions thus produced react with caffeine by electron transfer reaction, resulting in the formation of caffeine radical cation, which deprotonates in a fast step to produce C8OH adduct radicals. These radicals might react with PDP to give final product 1,3,7-trimethyluric acid and PO$_{4}^{\\bullet 2-}$ radicals, the latter propagates the chain reaction.

  12. Acute Superoxide Radical Scavenging Reduces Blood Pressure but Does Not Influence Kidney Function in Hypertensive Rats with Postischemic Kidney Injury

    Directory of Open Access Journals (Sweden)

    Zoran Miloradović

    2014-01-01

    Full Text Available Acute kidney injury (AKI is associated with significant morbidity and mortality in hypertensive surroundings. We investigated superoxide radical molecules influence on systemic haemodynamic and kidney function in spontaneously hypertensive rats (SHR with induced postischemic AKI. Experiment was performed in anesthetized adult male SHR. The right kidney was removed, and left renal artery was subjected to ischemia by clamping for 40 minutes. The treated group received synthetic superoxide dismutase mimetic TEMPOL in the femoral vein 5 minutes before, during, and 175 minutes after the period of reperfusion, while the control AKI group received the vehicle via the same route. All parameters were measured 24 h after renal reperfusion. TEMPOL treatment significantly decreased mean arterial pressure and total peripheral resistance P<0.05 compared to AKI control. It also increased cardiac output and catalase activity P<0.05. Lipid peroxidation and renal vascular resistance were decreased in TEMPOL P<0.05. Plasma creatinine and kidney morphological parameters were unchanged among TEMPOL treated and control groups. Our study shows that superoxide radicals participate in haemodynamic control, but acute superoxide scavenging is ineffective in glomerular and tubular improvement, probably due to hypertension-induced strong endothelial dysfunction which neutralizes beneficial effects of O2− scavenging.

  13. Homocysteine enhances superoxide anion release and NADPH oxidase assembly by human neutrophils. Effects on MAPK activation and neutrophil migration.

    Science.gov (United States)

    Alvarez-Maqueda, Moisés; El Bekay, Rajaa; Monteseirín, Javier; Alba, Gonzalo; Chacón, Pedro; Vega, Antonio; Santa María, Consuelo; Tejedo, Juan R; Martín-Nieto, José; Bedoya, Francisco J; Pintado, Elisabeth; Sobrino, Francisco

    2004-02-01

    Hyperhomocysteinaemia has recently been recognized as a risk factor of cardiovascular disease. However, the action mechanisms of homocysteine (Hcy) are not well understood. Given that Hcy may be involved in the recruitment of monocytes and neutrophils to the vascular wall, we have investigated the role of Hcy in essential functions of human neutrophils. We show that Hcy increased superoxide anion (O2*-) release by neutrophils to the extracellular medium, and that this effect was inhibited by superoxide dismutase and diphenyleneiodonium (DPI), an inhibitor of NADPH oxidase activity. The enzyme from rat peritoneal macrophages displayed a similar response. These effects were accompanied by a time-dependent increased translocation of p47phox and p67phox subunits of NADPH oxidase to the plasma membrane. We also show that Hcy increased intracellular H2O2 production by neutrophils, that Hcy enhanced the activation and phosphorylation of mitogen-activated protein kinases (MAPKs), specifically p38-MAPK and ERK1/2, and that the migration of neutrophils was increased by Hcy. Present results are the first evidence that Hcy enhances the oxidative stress of neutrophils, and underscore the potential role of phagocytic cells in vascular wall injury through O2*- release in hyperhomocysteinaemia conditions.

  14. Calculation of electron affinities of polycyclic aromatic hydrocarbons and solvation energies of their radical anion.

    Science.gov (United States)

    Betowski, Leon D; Enlow, Mark; Riddick, Lee; Aue, Donald H

    2006-11-30

    Electron affinities (EAs) and free energies for electron attachment (DeltaGo(a,298K)) have been directly calculated for 45 polynuclear aromatic hydrocarbons (PAHs) and related molecules by a variety of theoretical methods, with standard regression errors of about 0.07 eV (mean unsigned error = 0.05 eV) at the B3LYP/6-31 + G(d,p) level and larger errors with HF or MP2 methods or using Koopmans' Theorem. Comparison of gas-phase free energies with solution-phase reduction potentials provides a measure of solvation energy differences between the radical anion and neutral PAH. A simple Born-charging model approximates the solvation effects on the radical anions, leading to a good correlation with experimental solvation energy differences. This is used to estimate unknown or questionable EAs from reduction potentials. Two independent methods are used to predict DeltaGo(a,298K) values: (1) based upon DFT methods, or (2) based upon reduction potentials and the Born model. They suggest reassignments or a resolution of conflicting experimental EAs for nearly one-half (17 of 38) of the PAH molecules for which experimental EAs have been reported. For the antiaromatic molecules, 1,3,5-tri-tert-butylpentalene and the dithia-substituted cyclobutadiene 1, the reduction potentials lead to estimated EAs close to those expected from DFT calculations and provide a basis for the prediction of the EAs and reduction potentials of pentalene and cyclobutadiene. The Born model has been used to relate the electrostatic solvation energies of PAH and hydrocarbon radical anions, and spherical halide anions, alkali metal cations, and ammonium ions to effective ionic radii from DFT electron-density envelopes. The Born model used for PAHs has been successfully extended here to quantitatively explain the solvation energy of the C60 radical anion.

  15. Metal ions induced heat shock protein response by elevating superoxide anion level in HeLa cells transformed by HSE-SEAP reporter gene.

    Science.gov (United States)

    Yu, Zhanjiang; Yang, Xiaoda; Wang, Kui

    2006-06-01

    The aim of this work is to define the relationship between heat shock protein (HSP) and reactive oxygen species (ROS) in the cells exposed to different concentrations of metal ions, and to evaluate a new method for tracing the dynamic levels of cellular reactive oxygen species using a HSE-SEAP reporter gene. The expression of heat shock protein was measured using a secreted alkaline phosphatase (SEAP) reporter gene transformed into HeLa cell strain, the levels of superoxide anion (O(2)(-)) and hydrogen peroxide (H(2)O(2)) were determined by NBT reduction assay and DCFH staining flow cytometry (FCM), respectively. The experimental results demonstrated that the expression of heat shock protein induced by metal ions was linearly related to the cellular superoxide anion level before cytotoxic effects were observed, but not related to the cellular hydrogen peroxide level. The experimental results suggested that metal ions might induce heat shock protein by elevating cellular superoxide anion level, and thus the expression of heat shock protein indicated by the HSE-SEAP reporter gene can be an effective model for monitoring the dynamic level of superoxide anion and early metal-induced oxidative stress/cytotoxicity.

  16. Progress in Understanding Algal Bloom-Mediated Fish Kills: The Role of Superoxide Radicals, Phycotoxins and Fatty Acids.

    Science.gov (United States)

    Dorantes-Aranda, Juan José; Seger, Andreas; Mardones, Jorge I; Nichols, Peter D; Hallegraeff, Gustaaf M

    2015-01-01

    Quantification of the role of reactive oxygen species, phycotoxins and fatty acids in fish toxicity by harmful marine microalgae remains inconclusive. An in vitro fish gill (from rainbow trout Oncorhynchus mykiss) assay was used to simultaneously assess the effect in superoxide dismutase, catalase and lactate dehydrogenase enzymatic activities caused by seven species of ichthyotoxic microalgae (Chattonella marina, Fibrocapsa japonica, Heterosigma akashiwo, Karenia mikimotoi, Alexandrium catenella, Karlodinium veneficum, Prymnesium parvum). Quantification of superoxide production by these algae was also performed. The effect of purified phycotoxins and crude extracts was compared, and the effect of fatty acids is discussed. The raphidophyte Chattonella was the most ichthyotoxic (gill cell viability down to 35%) and also the major producer of superoxide radicals (14 pmol cell-1 hr-1) especially after cell lysis. The raphidophyte Heterosigma and dinoflagellate Alexandrium were the least toxic and had low superoxide production, except when A. catenella was lysed (5.6 pmol cell-1 hr-1). Catalase showed no changes in activity in all the treatments. Superoxide dismutase (SOD) and lactate dehydrogenase exhibited significant activity increases of ≤23% and 51.2% TCC (total cellular content), respectively, after exposure to C. marina, but SOD showed insignificant changes with remaining algal species. A strong relationship between gill cell viability and superoxide production or superoxide dismutase was not observed. Purified brevetoxins PbTx-2 and -3 (from Karenia brevis, LC50 of 22.1 versus 35.2 μg mL-1) and karlotoxin KmTx-2 (from Karlodinium; LC50 = 380 ng mL-1) could almost entirely account for the fish killing activity by those two dinoflagellates. However, the paralytic shellfish toxins (PST) GTX1&4, C1&C2, and STX did not account for Alexandrium ichthyotoxicity. Only aqueous extracts of Alexandrium were cytotoxic (≤65% decrease of viability), whereas crude

  17. Progress in Understanding Algal Bloom-Mediated Fish Kills: The Role of Superoxide Radicals, Phycotoxins and Fatty Acids.

    Directory of Open Access Journals (Sweden)

    Juan José Dorantes-Aranda

    Full Text Available Quantification of the role of reactive oxygen species, phycotoxins and fatty acids in fish toxicity by harmful marine microalgae remains inconclusive. An in vitro fish gill (from rainbow trout Oncorhynchus mykiss assay was used to simultaneously assess the effect in superoxide dismutase, catalase and lactate dehydrogenase enzymatic activities caused by seven species of ichthyotoxic microalgae (Chattonella marina, Fibrocapsa japonica, Heterosigma akashiwo, Karenia mikimotoi, Alexandrium catenella, Karlodinium veneficum, Prymnesium parvum. Quantification of superoxide production by these algae was also performed. The effect of purified phycotoxins and crude extracts was compared, and the effect of fatty acids is discussed. The raphidophyte Chattonella was the most ichthyotoxic (gill cell viability down to 35% and also the major producer of superoxide radicals (14 pmol cell-1 hr-1 especially after cell lysis. The raphidophyte Heterosigma and dinoflagellate Alexandrium were the least toxic and had low superoxide production, except when A. catenella was lysed (5.6 pmol cell-1 hr-1. Catalase showed no changes in activity in all the treatments. Superoxide dismutase (SOD and lactate dehydrogenase exhibited significant activity increases of ≤23% and 51.2% TCC (total cellular content, respectively, after exposure to C. marina, but SOD showed insignificant changes with remaining algal species. A strong relationship between gill cell viability and superoxide production or superoxide dismutase was not observed. Purified brevetoxins PbTx-2 and -3 (from Karenia brevis, LC50 of 22.1 versus 35.2 μg mL-1 and karlotoxin KmTx-2 (from Karlodinium; LC50 = 380 ng mL-1 could almost entirely account for the fish killing activity by those two dinoflagellates. However, the paralytic shellfish toxins (PST GTX1&4, C1&C2, and STX did not account for Alexandrium ichthyotoxicity. Only aqueous extracts of Alexandrium were cytotoxic (≤65% decrease of viability, whereas

  18. Synthesis of zwitterionic cobaltocenium borate and borata-alkene derivatives from a borole-radical anion.

    Science.gov (United States)

    Bauer, Jürgen; Braunschweig, Holger; Hörl, Christian; Radacki, Krzysztof; Wahler, Johannes

    2013-09-27

    Chemical single-electron reduction of 1-mesityl-2,3,4,5-tetraphenylborole (3) gave a stable radical anion [CoCp*2 ][3] as shown in earlier investigations. Herein, we present the reaction of [CoCp*2 ][3] with the 2,2,6,6-tetramethylpiperidine-N-oxyl radical (TEMPO), a common radical trap. Instead of radical recombination, the reaction proceeds through a redox pathway involving oxidation of the borole radical anion combined with reduction of TEMPO. This electron-transfer process is accompanied by a deprotonation reaction of the cobaltocenium counterion by the base TEMPO(-) to give TEMPO-H and a neutral cobalt(I) fulvene complex (7). The latter was not observed directly during the reaction, because it instantaneously reacts as a nucleophile attacking at the boron center of the in situ generated borole 3 to give the borate 6. However, 7 was synthesized independently by deprotonation of [CoCp*2 ][PF6 ]. In addition, the obtained zwitterionic cobaltocenium borate 6 undergoes a photolytic rearrangement to form the borata-alkene derivative 9 that thermally transforms to the chiral cobaltocenium borate 12. Our investigations are based on spectroscopic evidence, X-ray crystallography, elemental analysis, as well as DFT calculations. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Electrochemical, UV--visible and EPR studies on nitrofurantoin: nitro radical anion generation and its interaction with glutathione.

    Science.gov (United States)

    Núñez-Vergara, L J; Sturm, J C; Olea-Azar, C; Navarrete-Encina, P; Bollo, S; Squella, J A

    2000-05-01

    This paper deals with the reactivity of the nitro radical anion electrochemically generated from nitrofurantoin with glutathione. Cyclic voltammetry (CV) and controlled potential electrolysis were used to generate the nitro radical anion in situ and in bulk solution, respectively and cyclic voltammetry, UV--Visible and EPR spectroscopy were used to characterize the electrochemically formed radical and to study its interaction with GSH. By cyclic voltammetry on a hanging mercury drop electrode, the formation of the nitro radical anion was possible in mixed media (0.015M aqueous citrate/DMF, 40/60, pH 9) and in aprotic media. A second order decay of the radicals was determined, with a k2 value of 201 and 111 M(-1) s(-1), respectively. Controlled potential electrolysis generated the radical and its detection by cyclic voltammetry, UV--Visible and EPR spectroscopy was possible. When glutathione (GSH) was added to the solution, an unambiguous decay in the signals corresponding to a nitro radical anion were observed and using a spin trapping technique, a thiyl radical was detected. Electrochemical and spectroscopic data indicated that it is possible to generate the nitro radical anion from nitrofurantoin in solution and that GSH scavenged this reactive species, in contrast with other authors, which previously reported no interaction between them.

  20. Spin trapping of superoxide, alkyl- and lipid-derived radicals with derivatives of the spin trap EPPN.

    Science.gov (United States)

    Stolze, Klaus; Udilova, Natascha; Rosenau, Thomas; Hofinger, Andreas; Nohl, Hans

    2003-11-01

    The N-t-butyl-alpha-phenylnitrone derivative N-2-(2-ethoxycarbonyl-propyl)-alpha-phenylnitrone (EPPN) has recently been reported to form a superoxide spin adduct (t(1/2)=5.25 min at pH 7.0), which is considerably more stable than the respective N-t-butyl-alpha-phenylnitrone or 5,5-dimethylpyrroline N-oxide adducts (t(1/2) approximately 10 and 45s, respectively). In continuation of our previous studies on structure optimization of 5-(ethoxycarbonyl)-5-methyl-1-pyrroline N-oxide derivatives, a series of six different EPPN derivatives was synthesized and characterized by 1H NMR, 13C NMR and IR spectroscopy. The ethoxy group of EPPN was replaced by a propoxy, iso-propoxy, n-butoxy, sec-butoxy, and tert-butoxy moiety, as well as the phenyl by a pyridyl ring. Electron spin resonance spectra and stabilities of the superoxide adducts of the propoxy derivatives were found to be similar to those of the respective EPPN adduct, whereas the electron spin resonance spectra of the superoxide adducts of N-2-(2-ethoxycarbonyl-propyl)-alpha-(4-pyridyl) nitrone and the butoxy derivatives were accompanied by decomposition products. In contrast to the 5-(ethoxycarbonyl)-5-methyl-1-pyrroline N-oxide series, no significant improvement of the superoxide adduct stability could be obtained when the ethoxy group was replaced by other substituents. Carbon centered radical adducts derived from methanol, ethanol, formic acid and linoleic acid hydroperoxide were more stable than those of 5,5-dimethylpyrroline N-oxide, whereas among the alkoxyl radicals only the methoxyl radical adduct could be detected.

  1. Spectroscopic characterization of photoaccumulated radical anions: a litmus test to evaluate the efficiency of photoinduced electron transfer (PET processes

    Directory of Open Access Journals (Sweden)

    Maurizio Fagnoni

    2013-04-01

    Full Text Available Steady-state irradiation in neat acetonitrile of some aromatic nitriles, imides and esters (10−5–10−3 M solution in the presence of tertiary amines allowed the accumulation of the corresponding radical anions, up to quantitative yield for polysubstituted benzenes and partially with naphthalene and anthracene derivatives. The condition for such an accumulation was that the donor radical cation underwent further evolution that precluded back electron transfer and any chemical reaction with the radical anion. In fact, no accumulation occurred with 1,4-diazabicyclo[2.2.2]octane (DABCO, for which this condition is not possible. The radical anions were produced from benzene polyesters too, but decomposition began early. Ipso substitution was one of the paths with secondary amines and the only reaction with tetrabutylstannane. The results fully support the previously proposed mechanism for electron transfer (ET mediated photochemical alkylation of aromatic acceptors via radical ions and radical intermediates.

  2. Oxidative stress and enzymatic scavenging of superoxide radicals induced by solar UV-B radiation in Ulva canopies from southern Spain

    NARCIS (Netherlands)

    Bischof, K.; Janknegt, P.J.; Buma, A.G.J.; Rijstenbil, J.W.; Peralta, G.; Breeman, Arno

    2003-01-01

    The generation of reactive oxygen species (ROS) and scavenging of the superoxide radical by superoxide dismutase (SOD) was studied in mat-like canopies of the green macroalga Ulva rotundata Bliding in a tidal brine pond system in southern Spain. Artificial canopies were covered with different cut-of

  3. Photoelectron spectroscopy and density functional theory studies on the uridine homodimer radical anions

    Science.gov (United States)

    Jae Ko, Yeon; Storoniak, Piotr; Wang, Haopeng; Bowen, Kit H.; Rak, Janusz

    2012-11-01

    We report the photoelectron spectrum (PES) of the homogeneous dimer anion radical of uridine, (rU)2•-. It features a broad band consisting of an onset of ˜1.2 eV and a maximum at the electron binding energy (EBE) ranging from 2.0 to 2.5 eV. Calculations performed at the B3LYP/6-31++G** level of theory suggest that the PES is dominated by dimeric radical anions in which one uridine nucleoside, hosting the excess charge on the base moiety, forms hydrogen bonds via its O8 atom with hydroxyl of the other neutral nucleoside's ribose. The calculated adiabatic electron affinities (AEAGs) and vertical detachment energies (VDEs) of the most stable homodimers show an excellent agreement with the experimental values. The anionic complexes consisting of two intermolecular uracil-uracil hydrogen bonds appeared to be substantially less stable than the uracil-ribose dimers. Despite the fact that uracil-uracil anionic homodimers are additionally stabilized by barrier-free electron-induced proton transfer, their relative thermodynamic stabilities and the calculated VDEs suggest that they do not contribute to the experimental PES spectrum of (rU)2•-.

  4. Polymorphism and Metallic Behavior in BEDT-TTF Radical Salts with Polycyano Anions

    Directory of Open Access Journals (Sweden)

    Carlos J. Gómez-García

    2012-04-01

    Full Text Available Up to five different crystalline radical salts have been prepared with the organic donor BEDT-TTF and three different polynitrile anions. With the polynitrile dianion tcpd2− (=C[C(CN2]32−, two closely related radical salts: α'-(ET4tcpd·THF (1 (THF = tetrahydrofurane and α'-(ET4tcpd·H2O (2 have been prepared, depending on the solvent used in the synthesis. With the mono-anion tcnoetOH− (=[(NC2CC(OCH2CH2OHC(CN2]− two polymorphs with similar physical properties but different crystal packings have been synthesized: θ-(ET2(tcnoetOH (3 and β''-(ET2(tcnoetOH (4. Finally, with the mono-anion tcnoprOH− (=[(NC2CC(OCH2CH2CH2OHC(CN2]− we have prepared a metallic radical salt: β''-(ET2(tcnoprOH(CH2Cl2CH3Cl0.5 (5. Salts 1‑4 are semiconductors with high room temperature conductivities and activation energies in the range 0.1–0.5 eV, whereas salt 5 is metallic down to 0.4 K although it does not show any superconducting transition above this temperature.

  5. Electrochemical investigations of antioxidant interactions with radical anion and dianion of 1,3-dinitrobenzene

    Energy Technology Data Exchange (ETDEWEB)

    Arshad, Nasima [Department of Chemistry, Allama Iqbal Open University, Islamabad (Pakistan); Janjua, Naveed Kausar [Department of Chemistry, Quaid-i-Azam University, Islamabad (Pakistan)], E-mail: nkausarjanjua@yahoo.com; Ahmed, Safeer [Department of Chemistry, Quaid-i-Azam University, Islamabad (Pakistan); Khan, Athar Yaseen [Department of Chemistry, Allama Iqbal Open University, Islamabad (Pakistan); Skibsted, Leif H. [Food Chemistry, Department of Food Science, University of Copenhagen (Denmark)

    2009-11-01

    Interactions of five antioxidants (AO), quercetin (Q), morin (M), rutin (R), ascorbic acid (AA) and {beta}-carotene ({beta}-C) with anion radical and dianion of 1,3-dinitrobenzene (1,3-DNB) in two aprotic solvents - dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO) - have been studied by cyclic voltammetry using glassy carbon electrode. Electrochemical parameters - peak potential (E{sub p}), half-wave potential (E{sub 1/2}), and peak current (i{sub p}) - for the reduction of 1,3-DNB before and after the addition of various concentrations of antioxidants, were evaluated. A gradual decrease in the oxidation peak current and finally irreversibility in 1,3-DNB radical anion and dianion systems upon the addition of antioxidant, reveals their interactions. The homogeneous bi-molecular rate constant (k{sub 2}) was determined from electrochemical data. In comparison to all other antioxidants used, enhanced homogeneous second order rate constant for the interaction of morin with 1,3-DNB anion radical and dianion, was observed. This aspect is attributable to protonation initiated by hydrogen bonding and greater acidic nature of morin.

  6. Ultrasensitive detection of superoxide anion released from living cells using a porous Pt-Pd decorated enzymatic sensor.

    Science.gov (United States)

    Zhu, Xiang; Liu, Tingting; Zhao, Hongli; Shi, Libo; Li, Xiaoqing; Lan, Minbo

    2016-05-15

    Considering the critical roles of superoxide anion (O2(∙-)) in pathological conditions, it is of great urgency to establish a reliable and durable approach for real-time determination of O2(∙-). In this study, we propose a porous Pt-Pd decorated superoxide dismutase (SOD) sensor for qualitative and quantitative detection O2(∙-). The developed biosensor exhibits a fast, selective and linear amperometric response upon O2(∙-) in the concentration scope of 16 to 1,536 μM (R(2)=0.9941), with a detection limit of 0.13 μM (S/N=3) and a low Michaelis-Menten constant of 1.37 μM which indicating a high enzymatic activity and affinity to O2(∙-). Inspiringly, the proposed sensor possesses an ultrahigh sensitivity of 1270 μA mM(-1)cm(-2). In addition, SOD/porous Pt-Pd sensor exhibits excellent anti-interference property, reproducibility and long-term storage stability. Beyond our expectation, the trace level of O2(∙-) released from living cells has also been successfully captured. These satisfactory results are mainly ascribed to (1) the porous interface with larger surface area and more active sites to provide a biocompatible environment for SOD (2) the specific biocatalysis of SOD towards O2(∙-) and (3) porous Pt-Pd nanomaterials fastening the electron transfer. The superior electrochemical performance makes SOD/porous Pt-Pd sensor a promising candidate for monitoring the dynamic changes of O2(∙-)in vivo.

  7. Titanium dioxide nanoparticles enhance production of superoxide anion and alter the antioxidant system in human osteoblast cells

    Directory of Open Access Journals (Sweden)

    Niska K

    2015-02-01

    Full Text Available Karolina Niska,1 Katarzyna Pyszka,1 Cecylia Tukaj,2 Michal Wozniak,1 Marek Witold Radomski,3–5 Iwona Inkielewicz-Stepniak1 1Department of Medical Chemistry, 2Department of Electron Microscopy, Medical University of Gdansk, Gdansk, Poland; 3School of Pharmacy and Pharmaceutical Sciences, Trinity Biomedical Sciences Institute, The University of Dublin Trinity College, Dublin, Ireland; 4Kardio-Med Silesia, 5Silesian Medical University, Zabrze, Poland Abstract: Titanium dioxide (TiO2 nanoparticles (NPs are manufactured worldwide for a variety of engineering and bioengineering applications. TiO2NPs are frequently used as a material for orthopedic implants. However, to the best of our knowledge, the biocompatibility of TiO2NPs and their effects on osteoblast cells, which are responsible for the growth and remodeling of the human skeleton, have not been thoroughly investigated. In the research reported here, we studied the effects of exposing hFOB 1.19 human osteoblast cells to TiO2NPs (5–15 nm for 24 and 48 hours. Cell viability, alkaline phosphatase (ALP activity, cellular uptake of NPs, cell morphology, superoxide anion (O2•- generation, superoxide dismutase (SOD activity and protein level, sirtuin 3 (SIR3 protein level, correlation between manganese (Mn SOD and SIR, total antioxidant capacity, and malondialdehyde were measured following exposure of hFOB 1.19 cells to TiO2NPs. Exposure of hFOB 1.19 cells to TiO2NPs resulted in: (1 cellular uptake of NPs; (2 increased cytotoxicity and cell death in a time- and concentration-dependent manner; (3 ultrastructure changes; (4 decreased SOD and ALP activity; (5 decreased protein levels of SOD1, SOD2, and SIR3; (6 decreased total antioxidant capacity; (7 increased O2•- generation; and (8 enhanced lipid peroxidation (malondialdehyde level. The linear relationship between the protein level of MnSOD and SIR3 and between O2•- content and SIR3 protein level was observed. Importantly, the cytotoxic

  8. Vibrational Spectroscopy of Transient Dipolar Radicals via Autodetachment of Dipole-Bound States of Cold Anions

    Science.gov (United States)

    Huang, Dao-Ling; Liu, Hong-Tao; Dau, Phuong Diem; Wang, Lai-Sheng

    2014-06-01

    High-resolution vibrational spectroscopy of transient species is important for determining their molecular structures and understanding their chemical reactivity. However, the low abundance and high reactivity of molecular radicals pose major challenges to conventional absorption spectroscopic methods. The observation of dipole-bound states (DBS) in anions extend autodetachment spectroscopy to molecular anions whose corresponding neutral radicals possess a large enough dipole moment (>2.5 D).1,2 However, due to the difficulty of assigning the congested spectra at room temperature, there have been only a limited number of autodetachment spectra via DBS reported. Recently, we have built an improved version of a cold trap3 coupled with high-resolution photoelectron imaging.4 The first observation of mode-specific auotodetachment of DBS of cold phenoxide have shown that not only vibrational hot bands were completely suppressed, but also rotational profile was observed.5 The vibrational frequencies of the DBS were found to be the same as those of the neutral radical, suggesting that vibrational structures of dipolar radicals can be probed via DBS.5 More significantly, the DBS resonances allowed a number of vibrational modes with very weak Frank-Condon factors to be "lightened" up via vibrational autodetachment.5 Recently, our first high-resolution vibrational spectroscopy of the dehydrogenated uracil radical, with partial rotational resolution, via autodetachment from DBS of cold deprotonated uracil anions have been reported.6 Rich vibrational information is obtained for this important radical species. The resolved rotational profiles also allow us to characterize the rotational temperature of the trapped anions for the first time.6 1 K. R. Lykke, D. M. Neumark, T. Andersen, V. J. Trapa, and W. C. Lineberger, J. Chem. Phys. 87, 6842 (1987). 2 D. M. Wetzel, and J. I. Brauman, J. Chem. Phys. 90, 68 (1989). 3 P. D. Dau, H. T. Liu, D. L. Huang, and L. S. Wang, J. Chem. Phys

  9. Forgotten Radicals in Biology

    OpenAIRE

    2008-01-01

    Redox reactions play key roles in intra- and inter-cellular signaling, and in adaptative processes of tissues towards stress. Among the major free radicals with essential functions in cells are reactive oxygen species (ROS) including superoxide anion (O2 •-), hydroxyl radical (•OH) and reactive nitrogen species (RNS) such as nitric oxide (•NO). In this article, we review the forgotten and new radicals with potential relevance to cardiovascular pathophysiology. Approximately 0.3% of O2 •- pres...

  10. Excited states in electron-transfer reaction products : ultrafast relaxation dynamics of an isolated acceptor radical anion.

    OpenAIRE

    D. A. Horke; Roberts, G.M.; Verlet, J. R. R.

    2011-01-01

    The spectroscopy and ultrafast relaxation dynamics of excited states of the radical anion of a representative charge-transfer acceptor molecule, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, have been studied in the gas phase using time-resolved photoelectron spectroscopy. The photoelectron spectra reveal that at least two anion excited states are bound. Time-resolved studies show that both excited states are very short-lived and internally convert to the anion ground state, with the ...

  11. Reactions of isoprene and sulphoxy radical-anions - a possible source of atmospheric organosulphites and organosulphates

    Science.gov (United States)

    Rudziński, K. J.; Gmachowski, L.; Kuznietsova, I.

    2009-03-01

    Transformation of isoprene coupled with auto-oxidation of SIV in aqueous solutions was studied experimentally and by chemical-kinetic modelling over a 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 auto-oxidation 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=163), sulphurous acid mono-(4-hydroxy-2-methyl-but-2-enyl) ester (m/z=165), sulphuric acid mono-(2-methyl-4-oxo-but-2-enyl) ester (m/z=179), sulphuric acid mono-(4-hydroxy-2-methyl-but-2-enyl) ester (m/z=181), and possible structural isomers of these species - was indicated by electrospray ionisation mass spectrometric analysis of post-reaction mixtures. The experimental results 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 radical-anions by isoprene, the formation of sulphoxy radical-anions during further reactions of isoprene radicals, and the auto-oxidation of SIV itself. A chemical mechanism based on this idea was explored numerically to show good agreement with experimental data. In basic and neutral solutions, the model overestimated the consumption of isoprene, probably because reactions of primary sulphite and sulphate derivatives of isoprene with sulphoxy radical-anions were not included. Interaction of isoprene with sulphur(IV) species and oxygen can possibly result in formation of new organosulphate and organosulphite components of atmospheric aerosols and waters, and influence the distribution of reactive sulphur and oxygen species

  12. Accumulation of non-superoxide anion reactive oxygen species mediates nitrogen-limited alcoholic fermentation by Saccharomyces cerevisiae.

    Science.gov (United States)

    Mendes-Ferreira, Ana; Sampaio-Marques, Belém; Barbosa, Catarina; Rodrigues, Fernando; Costa, Vítor; Mendes-Faia, Arlete; Ludovico, Paula; Leão, Cecília

    2010-12-01

    Throughout alcoholic fermentation, nitrogen depletion is one of the most important environmental stresses that can negatively affect the yeast metabolic activity and ultimately leads to fermentation arrest. Thus, the identification of the underlying effects and biomarkers of nitrogen limitation is valuable for controlling, and therefore optimizing, alcoholic fermentation. In this study, reactive oxygen species (ROS), plasma membrane integrity, and cell cycle were evaluated in a wine strain of Saccharomyces cerevisiae during alcoholic fermentation in nitrogen-limiting medium under anaerobic conditions. The results indicated that nitrogen limitation leads to an increase in ROS and that the superoxide anion is a minor component of the ROS, but there is increased activity of both Sod2p and Cta1p. Associated with these effects was a decrease in plasma membrane integrity and a persistent cell cycle arrest at G(0)/G(1) phases. Moreover, under these conditions it appears that autophagy, evaluated by ATG8 expression, is induced, suggesting that this mechanism is essential for cell survival but does not prevent the cell cycle arrest observed in slow fermentation. Conversely, nitrogen refeeding allowed cells to reenter cell cycle by decreasing ROS generation and autophagy. Altogether, the results provide new insights on the understanding of wine fermentations under nitrogen-limiting conditions and further indicate that ROS accumulation, evaluated by the MitoTracker Red dye CM-H(2)XRos, and plasma membrane integrity could be useful as predictive markers of fermentation problems.

  13. Ratiometric fluorescence detection of superoxide anion based on AuNPs-BSA@Tb/GMP nanoscale coordination polymers.

    Science.gov (United States)

    Liu, Nan; Hao, Juan; Cai, Keying; Zeng, Mulan; Huang, Zhenzhong; Chen, Lili; Peng, Bingxian; Li, Ping; Wang, Li; Song, Yonghai

    2017-08-03

    A novel ratiometric fluorescence nanosensor for superoxide anion (O2(•-) ) detection was designed with gold nanoparticles-bovine serum albumin (AuNPs-BSA)@terbium/guanosine monophosphate disodium (Tb/GMP) nanoscale coordination polymers (NCPs) (AuNPs-BSA@Tb/GMP NCPs). The abundant hydroxyl and amino groups of AuNPs-BSA acted as binding points for the self-assembly of Tb(3+) and GMP to form core-shell AuNPs-BSA@Tb/GMP NCP nanosensors. The obtained probe exhibited the characteristic fluorescence emission of both AuNPs-BSA and Tb/GMP NCPs. The AuNPs-BSA not only acted as a template to accelerate the growth of Tb/GMP NCPs, but also could be used as the reference fluorescence for the detection of O2(•-) . The resulting AuNPs-BSA@Tb/GMP NCP ratiometric fluorescence nanosensor for the detection of O2(•-) demonstrated high sensitivity and selectivity with a wide linear response range (14 nM-10 μM) and a low detection limit (4.7 nM). Copyright © 2017 John Wiley & Sons, Ltd.

  14. Revisiting the electrochemical formation, stability and structure of radical and biradical anionic structures in dinitrobenzenes

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Munoz, Lindsay S.; Gonzalez, Felipe J. [Departamento de Quimica, Centro de Investigacion y Estudios Avanzados, Av. I.P.N. 2508. Col. San Pedro Zacatenco, 07360, D.F. (Mexico); Gonzalez, Ignacio [Departamento de Quimica, Universidad Autonoma Metropolitana-Iztapalapa, Area de Electroquimica, Apartado Postal 55-534, 09340, D.F. (Mexico); Goulart, Marilia O.F.; Abreu, Fabiane Caxico de; Ribeiro, Adriana Santos [Instituto de Quimica e Biotecnologia, Universidade Federal de Alagoas, Tabuleiro do Martins, Maceio, AL, 57072-970 (Brazil); Ribeiro, Rogerio Tavares; Longo, Ricardo L. [Departamento de Quimica Fundamental, Universidade Federal de Pernambuco, Av. Prof. Luiz Freire, s/n, Cid. Universitaria, Recife, PE, 50740-540 (Brazil); Navarro, Marcelo, E-mail: navarro@ufpe.b [Departamento de Quimica Fundamental, Universidade Federal de Pernambuco, Av. Prof. Luiz Freire, s/n, Cid. Universitaria, Recife, PE, 50740-540 (Brazil); Frontana, Carlos, E-mail: ultrabuho@yahoo.com.m [Departamento de Quimica, Centro de Investigacion y Estudios Avanzados, Av. I.P.N. 2508. Col. San Pedro Zacatenco, 07360, D.F. (Mexico)

    2010-11-30

    The effects of the position of a second nitroaromatic group (orthovs.paravs.meta) during reduction of nitrobenzenes were analysed. Cyclic voltammetric experiments in acetonitrile solution revealed that ortho-, meta- and para-dinitrobenzenes show two reversible reduction processes. An Electrochemical-Electron Spin Resonance (E-ESR) study showed that the corresponding radical anions of the ortho and para derivatives, electrogenerated during the first electron transfer uptake, remain the same even after the second monoelectronic process, increasing their intensity due to the presence of a comproportionation process (A{sup 2-} + A {yields} 2A{center_dot}{sup -}). For the case of the meta derivative, the electrogenerated radical anion at the first reduction peak is consumed at the second reduction step, forming a secondary radical species. During the electrochemical study of methyl 3,5-dinitrobenzoate, two successive and reversible electron processes were also observed; however, in this case, a very rare biradical dianion structure was found. The use of ESR-spectroelectrochemistry shed some light on controversial aspects of nitroaromatic reduction, especially concerning the second and further waves. These results were corroborated and interpreted with quantum chemical calculations of the molecular and electronic structures, electron affinities and spin densities. As a result, electrochemical mechanisms are presented and discussed.

  15. SYNTHESIS OF BLOCK COPOLYMER BY INTEGRATED LIVING ANIONIC POLYMERIZATION-ATOM TRANSFER RADICAL POLYMERIZATION (ATRP)

    Institute of Scientific and Technical Information of China (English)

    Bing Liu; Feng Liu; Ning Luo; Sheng-kang Ying; Qing Liu

    2000-01-01

    Alpha-trichloroacetoxy terminated polystyrene oligomer (PS-CH2CH2OCOCCl3) and poly-(styrene-b-butadiene)oligomer [P(S-b-B)-CH2CH2OCOCCl3)] were synthesized by living anionic polymeri-zation using n-butyllithium as initiator.Then the PS-CH2CH2OCOCCl3 (PS-Cl3) or P(S-b-B)-CH2CH2O-COCCl3 (PSB-Cl3) was used as the macroinitiator in the polymerization of (meth)acrylates in the presence of CuX/bpy. AB diblock and ABC triblock copolymers were prepared by the integrated living anionic polymerization (LAP)-atom transfer radical polymerization (ATRP). The structures of the PSB-Cl3 and the P(S-b-MMA) were identified by FTIR and 1H-NMR spectrum, respectively. A new way to design block copolymers (the combination of LAP and ATRP) was developed.

  16. Hypochlorite and superoxide radicals can act synergistically to induce fragmentation of hyaluronan and chondroitin sulphates

    DEFF Research Database (Denmark)

    Rees, Martin D; Hawkins, Clare Louise; Davies, Michael Jonathan

    2004-01-01

    chelators and the metal ion-binding protein BSA, consistent with chloramide decomposition and polymer fragmentation occurring via O2*--dependent one-electron reduction, possibly catalysed by trace metal ions. Polymer fragmentation induced by O2*- [generated by the superoxide thermal source 1, di-(4...

  17. Formation of the 42-mer Amyloid Radical and the Therapeutic Role of Superoxide Dismutase in Alzheimer's Disease

    Directory of Open Access Journals (Sweden)

    Kazuma Murakami

    2011-01-01

    Full Text Available Oxidative stress is closely involved in age-related diseases and ageing itself. There is evidence of the leading contribution of oxidative damage to neurodegenerative disease, in contrast to other diseases where oxidative stress plays a secondary role. The 42-mer amyloid β (Aβ42 peptide is thought to be a culprit in the pathogenesis of Alzheimer's disease (AD. Aβ42 aggregates form the oligomeric assembly and show neurotoxicity, causing synaptic dysfunction. Aβ42 also induces tissue oxidation (DNA/RNA, proteins, and lipids through trace metals (Cu, Zn, and Fe, which can be protected by antioxidant enzymes, vitamin C, and vitamin E. Superoxide dismutase catalyzes the conversion of toxic superoxide radical to less reactive hydrogen peroxide, contributing to protection from AD. Here we review the involvement of oxidative stress in AD progression induced from an imbalance between the radical formation of Aβ42 itself together with unique turn structure at positions Glu22 and Asp23 and several defense systems.

  18. Anion-radical oxygen centers in small (AgO)n clusters: density functional theory predictions

    CERN Document Server

    Trushin, Egor V

    2012-01-01

    Anion-radical form of the oxygen centers O(-) is predicted at the DFT level for small silver oxide particles having the AgO stoichiometry. Model clusters (AgO)n appear to be ferromagnetic with appreciable spin density at the oxygen centers. In contrast to these clusters, the Ag2O model cluster have no unpaired electrons in the ground state. The increased O/Ag ratio in the oxide particles is proved to be responsible for the spin density at oxygen centers.

  19. A new endoplasmic reticulum-targeted two-photon fluorescent probe for imaging of superoxide anion in diabetic mice.

    Science.gov (United States)

    Xiao, Haibin; Liu, Xiao; Wu, Chuanchen; Wu, Yaohuan; Li, Ping; Guo, Xiaomeng; Tang, Bo

    2017-05-15

    Excessive or unfolded proteins accumulation in endoplasmic reticulum (ER) will cause ER stress, which has evolved to involve in various metabolic diseases. In particular, ER stress plays an important role in the pathogenesis of diabetes. Both ER stress and course of diabetes accompany oxidative stress and production of reactive oxygen species (ROS), among which superoxide anion (O2(•-)) is the first produced ROS and has been recognized as cell signaling mediator involved in the physiological and pathological process of diabetes. Hence, the development of effective monitoring methods of O2(•-) in live cells and in vivo is of great importance for ascertaining the onset and progress of related diseases. Herein, a new endoplasmic reticulum-targeted two-photon fluorescent probe termed ER-BZT is designed and synthesized for imaging of O2(•-). The probe ER-BZT shows high sensitivity, selectivity, stability, and low cytotoxicity. Based on these superior properties, the rise of O2(•-) levels in endoplasmic reticulum induced with different stimuli is visualized by one- and two-photon fluorescence imaging. Most importantly, by utilizing ER-BZT, the two-photon fluorescence imaging results demonstrate that the endogenous O2(•-) concentration in abdominal or hepatic tissue of diabetic mice is higher than that in normal mice. Meanwhile, after treated with metformin, a broad-spectrum antidiabetic drug, the diabetic mice exhibit depressed O2(•-) level. The proposed two-photon probe, ER-BZT might serve as perfect tool to image the O2(•-) fluctuations and study the relevance between O2(•-) and various diseases in live cells and in vivo.

  20. Insights in the radical scavenging mechanism of syringaldehyde and generation of its anion

    Science.gov (United States)

    Yancheva, D.; Velcheva, E.; Glavcheva, Z.; Stamboliyska, B.; Smelcerovic, A.

    2016-03-01

    The ability of syringaldehyde, a naturally occurring phenolic antioxidant and medicinally important compound, to scavenge free radicals according different mechanisms was elucidated by computing the respective reaction enthalpies at DFT B3LYP/6-311++G** level. Bond dissociation enthalpy, ionization potentials and proton affinities were calculated in gas phase, benzene, water and DMSO in order to account for different environment (nonpolar lipid membranes and polar physiological liquids) where the antioxidant action in the living organism could take place and various experimental in vitro conditions. Molecular and electronic properties influencing the reactivity of syringaldehyde according to the different mechanisms were discussed in the light of the reported radical scavenging activities in crocin bleaching, oxidation potential of the first anodic peak and DPPH test. According to the calculated reaction enthalpies, in polar environment the syringaldehyde reacts preferably by sequential proton loss electron transfer which is related to the formation of a phenoxy anion. Such phenoxy anion was generated in DMSO solution and the changes in the force field, steric and electronic structure, resulting from the conversion, were described in detail based on the IR spectral data and DFT computations.

  1. Ab initio study of long-range electron transfer between biphenyl anion radical and naphthalene

    Institute of Scientific and Technical Information of China (English)

    李象远; 肖顺清; 何福城

    1999-01-01

    After the separation of the donor, the aeceptor, and the σ-type bridge from the π-σ-π system, the geometries of biphenyl, biphenyl anion radical, naphthalene, and naphthalene anion radical are optimized, and then the reorganization energy for the intermolecular electron transfer (ET) at the levels of HF/4-31G and HF/DZP is calculated. The ET matrix elements of the self-exchange reactions of the π-σ-π systems have been calculated by means of both the direct calculation based on the variational principle, and the transition energy between the molecular orbitals at the linear coordinate R=0.5. For the cross reactions, the ET matrix element and the geometry of the transition state are determined by searching the minimum energy splitting △min along the reaction coordinate. In the evaluation of the solvent reorganization energy of the ET in solution, the Marcus’ two-sphere model has been invoked. A few of ET rate constants for the intramolecular ET reactions for the π-σ-π systems, which contain

  2. Oxidative stress and enzymatic scavenging of superoxide radicals induced by solar UV-B radiation in Ulva canopies from southern Spain

    OpenAIRE

    Bischof, Kai; Janknegt, Paul J.; Buma, Anita G.J.; Rijstenbil, Jan W.; Peralta, Gloria; Breeman, Anneke M.

    2003-01-01

    The generation of reactive oxygen species (ROS) and scavenging of the superoxide radical by superoxide dismutase (SOD) was studied in mat-like canopies of the green macroalga Ulva rotundata Bliding in a tidal brine pond system in southern Spain. Artificial canopies were covered with different cut-off filters, generating different radiation conditions. ROS and SOD were assessed after three days of exposure. ROS induced lipid peroxidation depended on the position of individual thalli within the...

  3. A time-dependent density functional theory (TDDFT) interpretation of the optical spectra of zinc phthalocyanine π-cation and π-anion radicals1

    National Research Council Canada - National Science Library

    Ricciardi, Giampaolo; Rosa, Angela

    2009-01-01

    ...-anion radical prove to be in excellent agreement with the solution spectra and generally in line with deconvolution analyses of solution absorption and magnetic circular dichroism (MCD) spectra...

  4. Study of radicals, clusters and transition state species by anion photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, D.W.

    1994-08-01

    Free radicals, elemental and van der Waals clusters and transition state species for bimolecular chemical reactions are investigated using anion photoelectron spectroscopy. Several low-lying electronic states of ozone have been identified via photoelectron spectroscopy of O{sub 3}{sup {minus}}. A characterization of these states is important to models for atmospheric ozone reaction kinetics. The fluoroformyloxyl radical, FCO{sub 2}, has been investigated, providing vibrational frequencies and energies for two electronic states. The technique has also been employed to make the first direct observation and characterization of the NNO{sub 2} molecule. Several electronic states are observed for this species which is believed to play a role as a reactive intermediate in the N + NO{sub 2} reaction. The experimental results for all three of these radicals are supplemented by ab initio investigations of their molecular properties. The clusters investigations include studies of elemental carbon clusters (C{sub 2}{sup {minus}} {minus} C{sub 11}{sup {minus}}), and van der Waals clusters (X{sup {minus}}(CO{sub 2}){sub n}, X = I, Br, Cl; n {le} 13 and I{sup {minus}} (N{sub 2}O){sub n=1--11}). Primarily linear clusters are observed for the smaller carbon clusters, while the spectra of the larger clusters contain contribution from cyclic anion photodetachment. Very interesting ion-solvent interactions are observed in the X{sup {minus}}(CO{sub 2})n clusters. The transition state regions for several bimolecular chemical reactions have also been investigated by photodetachment of a negative ion precursor possessing a geometry similar to that of the transition state species. These spectra show features which are assigned to motions of the unstable neutral complex existing between reactants and products.

  5. Study of radicals, clusters and transition state species by anion photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, Don Wesley [Univ. of California, Berkeley, CA (United States)

    1994-08-01

    Free radicals, elemental and van der Waals clusters and transition state species for bimolecular chemical reactions are investigated using anion photoelectron spectroscopy. Several low-lying electronic states of ozone have been identified via photoelectron spectroscopy of O3-. A characterization of these states is important to models for atmospheric ozone reaction kinetics. The fluoroformyloxyl radical, FCO2, has been investigated, providing vibrational frequencies and energies for two electronic states. The technique has also been employed to make the first direct observation and characterization of the NNO2 molecule. Several electronic states are observed for this species which is believed to play a role as a reactive intermediate in the N + NO2 reaction. The experimental results for all three of these radicals are supplemented by ab initio investigations of their molecular properties. The clusters investigations include studies of elemental carbon clusters (C2- - C11-), and van der Waals clusters (X-(CO2)n, X = I, Br, Cl; n {le} 13 and I- (N2O)n=1--11). Primarily linear clusters are observed for the smaller carbon clusters, while the spectra of the larger clusters contain contribution from cyclic anion photodetachment. Very interesting ion-solvent interactions are observed in the X-(CO2)n clusters. The transition state regions for several bimolecular chemical reactions have also been investigated by photodetachment of a negative ion precursor possessing a geometry similar to that of the transition state species. These spectra show features which are assigned to motions of the unstable neutral complex existing between reactants and products.

  6. Nitro radical anion formation from nitrofuryl substituted 1,4-dihydropyridine derivatives in mixed and non-aqueous media.

    Science.gov (United States)

    Argüello, J; Núñez-Vergara, L J; Bollo, S; Squella, J A

    2006-09-01

    Three new nitrofuryl substituted 1,4-dihydropyridine derivatives were electrochemically tested in the scope of newly found compounds useful as chemotherapeutic alternative to the Chagas' disease. All the compounds were capable to produce nitro radical anions sufficiently stabilized in the time window of the cyclic voltammetric experiment. In order to quantify the stability of the nitro radical anion we have calculated the decay constant, k2. Furthermore, from the voltammetric results, some parameters of biological significance as E7(1) (indicative of in vivo nitro radical anion formation) and KO2 (thermodynamic indicator of oxygen redox cycling) have been calculated. From the comparison of E7(1), KO2 and k2 values between the studied nitrofuryl 1,4-DHP derivatives and well-known current drugs an auspicious activity for one of the studied compounds i.e. FDHP2, can be expected.

  7. Study of organic radicals through anion photoelectron velocity-map imaging spectroscopy

    Science.gov (United States)

    Dixon, Andrew Robert

    We report preliminary results on the photoelectron imaging of phenylcarbene, cyanophenylcarbene, and chlorophenylcarbene anions. Triplet phenylcarbene is observed to have an EA of ≤ 0.83 eV, considerably lower than the previously indirectly-determined value. Transitions to the singlet and triplet ground state of both cyanophenylcarbene and chlorophenylcarbene are observable, though unidentified bands make full assignment difficult. Cyanophenylcarbene is found to have a triplet ground-state, with a tentative EA of 2.04 eV. Chlorophenylcarbene is found to have a singlet ground-state. The phenyl-group is found to favor the singlet state slightly. The cyanofluoromethyl radical, FC(H)CN, was estimated to have an EA of 1.53 +/- 0.08 eV, by a combination of experimental and theoretical results.. With similar methodology, we report the adiabatic electron affinity of the cyanobenzyl radical, EA(PhCHCN) = 1.90 +/- 0.01 eV, and assign an upper limit of the EA for the chlorobenzyl radical, EA(PhCHCl) ≤ 1.12 eV. These values were used to estimate the C-H bond dissociation energy (BDE)s for these substituted methanes. Fluoroacetonitrile was found to have a BDE of D H198 = 90.7 +/- 2.8 kcal mol□1. The C-H bond dissociation energies at the benzyl-alpha sites of the phenylmethanes are determined as 80.9 +/- 2.3 kcal mol-1 for benzyl nitrile and an upper limit of 84.2 kcal mol-1 for benzyl chloride. These results are discussed in terms of substituent interactions in a simple MO framework and in relation to other similar molecules, including recently reported results for chloroacetonitrile. The 532 nm photoelectron spectrum of glyoxal provides the first direct spectroscopic determination of the adiabatic electron affinity, EA = 1.10(2) eV. This assignment is supported by a Franck-Condon simulation of the experimental spectrum that successfully reproduces the observed spectral features. The vertical detachment energy (VDE) of the glyoxal radical anion is determined as VDE = 1

  8. Ab initio ro-vibronic spectroscopy of the 2Π PCS radical and +1ΣPCS- anion

    Science.gov (United States)

    Finney, Brian; Mitrushchenkov, Alexander O.; Francisco, Joseph S.; Peterson, Kirk A.

    2016-12-01

    Near-equilibrium potential energy surfaces have been calculated for both the PCS radical and its anion using a composite coupled cluster approach based on explicitly correlated F12 methods in order to provide accurate structures and spectroscopic properties. These transient species are still unknown and the present study provides theoretical predictions of the radical and its anion for the first time. Since these species are strongly suggested to play an important role as intermediates in the interstellar medium, the rotational and vibrational spectroscopic parameters are presented to help aid in the identification and assignment of these spectra. The rotational constants produced will aid in ground-based observation. Both the PCS radical and the PCS- anion are linear. In the PCS- anion, which has a predicted adiabatic electron binding energy (adiabatic electron affinity of PCS) of 65.6 kcal/mol, the P-C bond is stronger than the corresponding neutral radical showing almost triple bond character, while the C-S bond is weaker, showing almost single bond character in the anion. The PCS anion shows a smaller rotational constant than that of the neutral. The ω3 stretching vibrational frequencies of PCS- are red-shifted from the radical, while the ω1 and ω2 vibrations are blue-shifted with ω1 demonstrating the largest blue shift. The ro-vibronic spectrum of the PCS radical has been accurately calculated in variational nuclear motion calculations including both Renner-Teller (RT) and spin-orbit (SO) coupling effects using the composite potential energy near-equilibrium potential energy and coupled cluster dipole moment surfaces. The spectrum is predicted to be very complicated even at low energies due to the presence of a strong Fermi resonance between the bending mode and symmetric stretch, but also due to similar values of the bending frequency, RT, and SO splittings.

  9. [Reliability of electron-transport membranes and the role of oxygen anion-radicals in aging: stochastic modulation of the genetic program].

    Science.gov (United States)

    Kol'tover, V K

    2010-01-01

    All biomolecular constructions and nanorecators are designed to perform preset functions. All of them operate with limited reliability, namely, for each and every device or bionanoreactor normal operation alternates with accidental malfunctions (failures). Timely preventive maintenance replacement (prophylaxis) of functional elements in cells and tissues, the so-called turnover, is the main line of assuring high system reliability of organism as a whole. There is a finite number of special groups of genes (reliability assuring structures, RAS) that perform supervisory functions over the preventive maintenance. In a hierarchic pluricellular organism, RAS are genetic regulatory networks of a special group of cells, like hypothalamic neurons in the suprachiasmatic nucleus of mammals. Of the primary importance is limited reliability of mitochondrial nanoreactors, since the random malfunctions of electron transport chains produce reactive anion-radicals of oxygen (superoxide radical, O2*(-)). With time, O2*(-) radicals initiate accumulation of irreparable damages in RAS. When these damages accumulate up to preset threshold level, a fatal decrease in reliability of RAS occurs. Thus, aging is the stochastic consequence of programmed deficiency in reliability of biomolecular constructions and nanoreactors including the genetically preset limit of the system reliability. This reliability approach provides the realistic explanation of the data on prolongation of life of experimental animals with antioxidants as well as the explanation of similar "hormetic" effects of ionizing radiation in low doses.

  10. Signaling Pathways Linked to Serotonin-Induced Superoxide Anion Production: A Physiological Role for Mitochondria in Pulmonary Arteries

    Science.gov (United States)

    Genet, Nafiisha; Billaud, Marie; Rossignol, Rodrigue; Dubois, Mathilde; Gillibert-Duplantier, Jennifer; Isakson, Brant E.; Marthan, Roger; Savineau, Jean-Pierre; Guibert, Christelle

    2017-01-01

    Serotonin (5-HT) is a potent vasoconstrictor agonist and contributes to several vascular diseases including systemic or pulmonary hypertension and atherosclerosis. Although superoxide anion (O2•_) is commonly associated to cellular damages due to O2•_ overproduction, we previously demonstrated that, in physiological conditions, O2•_ also participates to the 5-HT contraction in intrapulmonary arteries (IPA). Here, we focused on the signaling pathways leading to O2•_ production in response to 5-HT in rat IPA. Using electron paramagnetic resonance on rat IPA, we showed that 5-HT (100 μM)-induced O2•_ production was inhibited by ketanserin (1 μM—an inhibitor of the 5-HT2 receptor), absence of extracellular calcium, two blockers of voltage-independent calcium permeable channels (RHC80267 50 μM and LOE-908 10 μM) and a blocker of the mitochondrial complex I (rotenone—100 nM). Depletion of calcium from the sarcoplasmic reticulum or nicardipine (1 μM—an inhibitor of the L-type voltage-dependent calcium channel) had no effect on the 5-HT-induced O2•_ production. O2•_ levels were also increased by α-methyl-5-HT (10 μM—a 5-HT2 receptors agonist) whereas GR127935 (1 μM—an antagonist of the 5-HT1B/D receptor) and citalopram (1 μM—a 5-HT transporter inhibitor) had no effect on the 5-HT-induced O2•_ production. Peroxynitrites were increased in response to 5-HT (100 μM). In isolated pulmonary arterial smooth muscle cells loaded with rhod-2 or mitosox probes, we respectively showed that 5-HT increased both mitochondrial calcium and O2•_ levels, which were both abrogated in absence of extracellular calcium. Mitochondrial O2•_ levels were also abolished in the presence of rotenone (100 nM). In pulmonary arterial smooth muscle cells loaded with TMRM, we showed that 5-HT transiently depolarized the mitochondrial membrane whereas in the absence of extracellular calcium the mitochondrial membrane depolarisation was delayed and sustained in

  11. The effect of orexin-A on cardiac dysfunction mediated by NADPH oxidase-derived superoxide anion in ventrolateral medulla.

    Directory of Open Access Journals (Sweden)

    Jun Chen

    Full Text Available Hypocretin/orexin-producing neurons, located in the perifornical region of the lateral hypothalamus area (LHA and projecting to the brain sites of rostral ventrolateral medulla (RVLM, involve in the increase of sympathetic activity, thereby regulating cardiovascular function. The current study was designed to test the hypothesis that the central orexin-A (OXA could be involved in the cardiovascular dysfunction of acute myocardial infarction (AMI by releasing NAD(PH oxidase-derived superoxide anion (O2 (- generation in RVLM, AMI rat model established by ligating the left anterior descending (LAD coronary artery to induce manifestation of cardiac dysfunction, monitored by the indicators as heart rate (HR, heart rate variability (HRV, mean arterial pressure (MAP and left intraventricular pressure. The results showed that the expressions of OXA in LHA and orexin 1 receptor (OX1R increased in RVLM of AMI rats. The double immunofluorescent staining indicated that OX1R positive cells and NAD(PH oxidative subunit gp91phox or p47phox-immunoreactive (IR cells were co-localized in RVLM. Microinjection of OXA into the cerebral ventricle significantly increased O2 (- production and mRNA expression of NAD(PH oxidase subunits when compared with aCSF-treated ones. Exogenous OXA administration in RVLM produced pressor and tachycardiac effects. Furthermore, the antagonist of OX1R and OX2R (SB-408124 and TCS OX2 29, respectively or apocynin (APO, an inhibitor of NAD(PH oxidase, partly abolished those cardiovascular responses of OXA. HRV power spectral analysis showed that exogenous OXA led to decreased HF component of HRV and increased LF/HF ratio in comparison with aCSF, which suggested that OXA might be related to sympathovagal imbalance. As indicated by the results, OXA might participate in the central regulation of cardiovascular activities by disturbing the sympathovagal balance in AMI, which could be explained by the possibility that OXR and NAD(PH-derived O

  12. Transient Raman spectra, structure, and thermochemistry of the thiocyanate dimer radical anion in water

    Science.gov (United States)

    Janik, Ireneusz; Carmichael, Ian; Tripathi, G. N. R.

    2017-06-01

    Time-resolved resonance-enhanced Stokes and anti-Stokes Raman spectra of the thiocyanate dimer radical anion, (SCN)2•-, prepared by pulse radiolysis in water, have been obtained and interpreted in conjunction with theoretical calculations to provide detailed information on the molecular geometry and bond properties of the species. The structural properties of the radical are used to develop a molecular perspective on its thermochemistry in an aqueous solution. Twenty-nine Stokes Raman bands of the radical observed in the 120-4200 cm-1 region are assigned in terms of the strongly enhanced 220 cm-1 fundamental, weakly enhanced 721 cm-1, and moderately enhanced 2073 cm-1 fundamentals, their overtones, and combinations. Calculations by range-separated hybrid density functionals (ωB97x and LC-ωPBE) support the spectroscopic assignments of the 220 cm-1 vibration to a predominantly SS stretching mode and the features at 721 cm-1 and 2073 cm-1 to CS and CN symmetric stretching modes, respectively. The corresponding bond lengths are 2.705 (±0.036) Å, 1.663 (±0.001) Å, and 1.158 (±0.002) Å. A first order anharmonicity of 1 cm-1 determined for the SS stretching mode suggests a convergence of vibrational states at an energy of ˜1.5 eV, using the Birge-Sponer extrapolation. This value, estimated for the radical confined in solvent cage, compares well with the calculated gas-phase energy of 1.26 ± 0.04 eV required for the radical to dissociate into SCN• and SCN- fragments. The enthalpy of dissociation drops to 0.60 ± 0.03 eV in water when solvent dielectric effects on the radical and its dissociation products upon S-S bond scission are incorporated in the calculations. No frequency shift or spectral broadening was observed between light and heavy water solvents, indicating that the motion of solvent molecules in the hydration shell has no perceptible effect on the intramolecular dynamics of the radical. The Stokes and anti-Stokes Raman frequencies were found to be

  13. The Ability of Bile to Scavenge Superoxide Radicals and Pigment Gallstone Formation in Guinea Pigs

    Directory of Open Access Journals (Sweden)

    Cong Lin

    1996-01-01

    Full Text Available After partial ligation of the common bile duct (CBD of guinea pigs, 14 of 16 animals developed pigment gallstones within one week (S group. Intraperitoneal injection of Vit. E and C, each 10 mg/kg daily from 3 days before CBD ligation to one week after the operation (S+V group, decreased the gallstone incidence to 5/14 (exact probability0.05, but Vit. E and C normalized the SR, and the difference between S group and S+V group was significant (p<0.05. These results suggested that Vit. E and C, known as antioxidants, enhanced the ability to scavenge oxygen radical in S+V group; and that in addition to the increases of UCB and Ca2+ concentrations, the participation of oxygen radicals might be of importance for pigment gallstone formation induced by bile duct obstruction.

  14. Ubiquitous trisulfur radical anion: fundamentals and applications in materials science, electrochemistry, analytical chemistry and geochemistry.

    Science.gov (United States)

    Chivers, Tristram; Elder, Philip J W

    2013-07-21

    The trisulfur radical anion [S3]˙(-) is well-known from inorganic chemistry textbooks as the blue chromophore in ultramarine blues in which this highly reactive species is trapped in a zeolitic framework. Recent findings have revealed that [S3]˙(-) has a multi-faceted role in a variety of media, including alkali metal-sulfur batteries, aqueous solutions at high temperatures and pressures, and ionic liquids; it has also been used to detect trace amounts of water in organic solvents. This tutorial review illustrates how various physical techniques are used to identify a reactive species in solution and shows how elucidation of electronic structures can be used to explain spectroscopic and structural properties. Examples of the function of [S3]˙(-) in materials science, electrochemistry, analytical chemistry and geochemistry are used to illustrate the widespread influence of this fundamentally important triatomic sulfur species.

  15. Release of reactive oxygen intermediates (superoxide radicals, hydrogen peroxide, and hydroxyl radicals) and peroxidase in germinating radish seeds controlled by light, gibberellin, and abscisic acid.

    Science.gov (United States)

    Schopfer, P; Plachy, C; Frahry, G

    2001-04-01

    Germination of radish (Raphanus sativus cv Eterna) seeds can be inhibited by far-red light (high-irradiance reaction of phytochrome) or abscisic acid (ABA). Gibberellic acid (GA3) restores full germination under far-red light. This experimental system was used to investigate the release of reactive oxygen intermediates (ROI) by seed coats and embryos during germination, utilizing the apoplastic oxidation of 2',7'-dichlorofluorescin to fluorescent 2',7'-dichlorofluorescein as an in vivo assay. Germination in darkness is accompanied by a steep rise in ROI release originating from the seed coat (living aleurone layer) as well as the embryo. At the same time as the inhibition of germination, far-red light and ABA inhibit ROI release in both seed parts and GA3 reverses this inhibition when initiating germination under far-red light. During the later stage of germination the seed coat also releases peroxidase with a time course affected by far-red light, ABA, and GA3. The participation of superoxide radicals, hydrogen peroxide, and hydroxyl radicals in ROI metabolism was demonstrated with specific in vivo assays. ROI production by germinating seeds represents an active, developmentally controlled physiological function, presumably for protecting the emerging seedling against attack by pathogens.

  16. Sensitive electrochemical detection of superoxide anion using gold nanoparticles distributed poly(methyl methacrylate)-polyaniline core-shell electrospun composite electrode.

    Science.gov (United States)

    Santhosh, Padmanabhan; Manesh, Kalayil Manian; Lee, Se-Hee; Uthayakumar, Sivaperumal; Gopalan, Anantha Iyengar; Lee, Kwang-Pill

    2011-04-21

    In the present communication, a novel composite nanofibrous electrode is developed for the detection of superoxide anion (O(2)˙(-)) in phosphate buffered saline (PBS). The composite fiber electrode is fabricated by dispersing gold nanoparticles onto poly(methyl methacrylate) (PMMA)-polyaniline (PANI) core-shell electrospun nanofibers. The constructed architecture is proven to be a favorable environment for the immobilization of the enzyme, superoxide dismutase (SOD). Direct electron transfer is achieved between SOD and the electrode with an electron transfer rate constant of 8.93 s(-1). At an applied potential of +300 mV, PMMA/PANI-Au(nano)/SOD-ESCFM shows highly sensitive detection of O(2)˙(-). In addition to this, quantification of different activities of SOD is realized at PMMA/PANI-Au(nano)/SOD-ESCFM. These analytical features offer great potential for construction of the third-generation O(2)˙(-) biosensor.

  17. A study of quasi reversible nitro radical anion from -nitrostyrene at wax-impregnated carbon paste electrode

    Indian Academy of Sciences (India)

    Ronald J Mascarenhas; Irishi N Namboothiri; B S Sherigara; Vijayakumar K Reddy

    2006-05-01

    A comprehensive study of the electrochemical reduction of -nitrostyrene and the corresponding heterocyclic analogue has been carried out in aprotic media using wax-impregnated carbon paste electrodes. Nitrostyrene exhibits quasi-reversible reduction process in aprotic medium at the waximpregnated carbon paste electrodes as compared to other electrodes reported in the literature. The nitroradical anion couple detected in the presence of tetrabutyl ammonium perchlorate is found to be stable only in aprotic media. Though, as reported, the pharmacological activity related to this nitro radical anion and its therapeutic value are related to the stability of the nitro radical anion, the stability itself depends on the electrode system employed. Added benzoic acid is found to bring about a positive shift in cathodic peak potential.

  18. A study on the comparison of antioxidant effects among cultivated ginseng, and cultivated wild ginseng extracts -Using the measurement of superoxide and hydroxy radical scavenging activities-

    Directory of Open Access Journals (Sweden)

    Tae Jin, Rhim

    2009-06-01

    Full Text Available Objectives : The objective of this study was to compare the antioxidant effects among cultivated wild ginseng and ginseng extracts. Methods : In vitro antioxidant activities were examined by superoxide and hydroxyl radical scavenging activities of ginseng and cultivated wild ginseng extracts. Results : 1. In the superoxide radical scavenging activities of ginseng and cultivated wild ginseng extracts, antioxidant activities of cultivated wild ginseng extracts was showed higher than cultivated ginseng in the concentration of 0.25 and 0.50㎎/㎖. 2. In the hydroxyl radical scavenging activities of ginseng and cultivated wild ginseng extracts, antioxidant activities of cultivated wild ginseng extracts was showed higher than cultivated ginseng in the concentration of 1.0, 2.5, and 5.0㎎/㎖. Conclusions : In summary, the results of this study demonstrate that cultivated wild ginseng extracts had higher antioxidant activities to cultivated ginseng.

  19. Potent Free Radical Scavenging Activity of Propol Isolated from Brazilian Propolis

    National Research Council Canada - National Science Library

    Purusotam Basnet; Tetsuya Matsuno; Richard Neidlein

    1997-01-01

    ...) generated superoxide anion assay systems. The free radical scavenging activity guided fractionation and chemical analysis led to the isolation of a new compound, propol {3-[4-hydroxy-3-(3-oxo-but-1-enyl)-phenyl]-acrylic acid...

  20. A superoxide anion biosensor based on direct electron transfer of superoxide dismutase on sodium alginate sol-gel film and its application to monitoring of living cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xiuhua; Han Min; Bao Jianchun; Tu Wenwen [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210097 (China); Dai Zhihui, E-mail: daizhihuii@njnu.edu.cn [Jiangsu Key Laboratory of Biofunctional Materials, College of Chemistry and Materials Science, Nanjing Normal University, Nanjing 210097 (China)

    2012-03-02

    Highlights: Black-Right-Pointing-Pointer The direct electron transfer of SOD was facilitated on SA sol-gel film. Black-Right-Pointing-Pointer O{sub 2}{center_dot}{sup -} sensor has high selectivity, stability and sensitivity. Black-Right-Pointing-Pointer The proposed measurement for O{sub 2}{center_dot}{sup -} can be applied in living cells. - Abstract: The direct electron transfer of superoxide dismutase (SOD) was greatly facilitated by sodium alginate (SA) sol-gel film with the formal potential of 0.14 V, which was just located between O{sub 2}{center_dot}{sup -}/O{sub 2} and O{sub 2}{center_dot}{sup -}/H{sub 2}O{sub 2}. The preparation of the SOD/SA modified electrode was simple without any mediators or promoters. Based on bimolecular recognition for specific reactivity of SOD/SA toward O{sub 2}{center_dot}{sup -}, the SOD modified electrode was utilized to measure O{sub 2}{center_dot}{sup -} with good analytical performance, such as low applied potential (0 V), high selectivity (no obvious interference), wide linear range (0.44-229.88 {mu}M) and low detection limit (0.23 {mu}M) in pH 7.0 phosphate buffer solution. Furthermore, it could be successfully exploited for the determination of O{sub 2}{center_dot}{sup -} released from living cells directly adhered on the modified electrode surface. Thus, the proposed O{sub 2}{center_dot}{sup -} biosensor, combining with the properties of SA sol-gel film, provided a novel approach for protein immobilization, direct electron transfer study of the immobilized protein and real-time determination of O{sub 2}{center_dot}{sup -} released from living cells.

  1. Prion-derived copper-binding peptide fragments catalyze the generation of superoxide anion in the presence of aromatic monoamines

    Directory of Open Access Journals (Sweden)

    Tomonori Kawano

    2007-01-01

    Full Text Available Objectives: Studies have proposed two opposing roles for copper-bound forms of prion protein (PrP as an anti-oxidant supporting the neuronal functions and as a pro-oxidant leading to neurodegenerative process involving the generation of reactive oxygen species. The aim of this study is to test the hypothesis in which putative copper-binding peptides derived from PrP function as possible catalysts for monoamine-dependent conversion of hydrogen peroxide to superoxide in vitro. Materials and methods: Four peptides corresponding to the copper (II-binding motifs in PrP were synthesized and used for analysis of peptide-catalyzed generation of superoxide in the presence of Cu (II and other factors naturally present in the neuronal tissues. Results: Among the Cu-binding peptides tested, the amino acid sequence corresponding to the Cu-binding site in the helical region was shown to be the most active for superoxide generation in the presence of Cu(II, hydrogen peroxide and aromatic monoamines, known precursors or intermediates of neurotransmitters. Among monoamines tested, three compounds namely phenylethylamine, tyramine and benzylamine were shown to be good substrates for superoxide-generating reactions by the Cu-bound helical peptide. Conclusions: Possible roles for these reactions in development of prion disease were suggested.

  2. Vibronic spectra of the p-benzoquinone radical anion and cation: a matrix isolation and computational study

    OpenAIRE

    Piech, Krzysztof; Bally, Thomas; Ichino, Takatoshi; Stanton, John

    2014-01-01

    The electronic and vibrational absorption spectra of the radical anion and cation of p-benzoquinone (PBQ) in an Ar matrix between 500 and 40 000 cm⁻¹ are presented and discussed in detail. Of particular interest is the radical cation, which shows very unusual spectroscopic features that can be understood in terms of vibronic coupling between the ground and a very low-lying excited state. The infrared spectrum of PBQ˙⁺ exhibits a very conspicuous and complicated pattern of features above 1900 ...

  3. Excited states in electron-transfer reaction products: ultrafast relaxation dynamics of an isolated acceptor radical anion.

    Science.gov (United States)

    Horke, Daniel A; Roberts, Gareth M; Verlet, Jan R R

    2011-08-04

    The spectroscopy and ultrafast relaxation dynamics of excited states of the radical anion of a representative charge-transfer acceptor molecule, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, have been studied in the gas phase using time-resolved photoelectron spectroscopy. The photoelectron spectra reveal that at least two anion excited states are bound. Time-resolved studies show that both excited states are very short-lived and internally convert to the anion ground state, with the lower energy state relaxing within 200 fs and a near-threshold valence-excited state relaxing on a 60 fs time scale. These excited states, and in particular the valence-excited state, present efficient pathways for electron-transfer reactions in the highly exergonic inverted region which commonly displays rates exceeding predictions from electron-transfer theory.

  4. Effects of microsolvation on uracil and its radical anion: Uracil.(H2O)n (n=1-5)

    Science.gov (United States)

    Kim, Sunghwan; Schaefer, Henry F.

    2006-10-01

    Microsolvation effects on the stabilities of uracil and its anion have been investigated by explicitly considering the structures of complexes of uracil with up to five water molecules at the B3LYP /DZP++ level of theory. For all five systems, the global minimum of the neutral cluster has a different equilibrium geometry from that of the radical anion. Both the vertical detachment energy (VDE) and adiabatic electron affinity (AEA) of uracil are predicted to increase gradually with the number of hydrating molecules, qualitatively consistent with experimental results from a photodetachment-photoelectron spectroscopy study [J. Schiedt et al., Chem. Phys. 239, 511 (1998)]. The trend in the AEAs implies that while the conventional valence radical anion of uracil is only marginally bound in the gas phase, it will form a stable anion in aqueous solution. The gas-phase AEA of uracil (0.24eV) was higher than that of thymine by 0.04eV and this gap was not significantly affected by microsolvation. The largest AEA is that predicted for uracil•(H2O)5, namely, 0.96eV. The VDEs range from 0.76to1.78eV.

  5. Highly efficient green-light ionization of an aryl radical anion: key step in a catalytic cycle of electron formation.

    Science.gov (United States)

    Kerzig, Christoph; Goez, Martin

    2014-12-14

    A sustainable generation of hydrated electrons with green light would allow solar-driven applications of this potent reductant, such as the detoxification of halogenated organic waste. Using two-color laser flash photolysis, we have studied the photoionizations of the 1,5-naphthalene disulfonate radical anion and triplet with 532 nm as well as 355 nm. The radical anion is prepared by reducing the triplet with the bioavailable ascorbate monoanion under physiological conditions; its photoionization recovers the starting substrate, so turns the reaction sequence into a catalytic cycle. A comparison of the four ionizations suggests that their efficiency is strongly influenced by the electronic configuration of the state ejecting the electron. The quantum yield for ionizing the radical anion with 532 nm (0.27) is at least four times higher than for the very few known examples of such green-light ionizations and comparable to the most efficient UV ionizations known to date, so this system might represent a breakthrough towards the "green" production of hydrated electrons.

  6. Dramatic enhancement of organics degradation and electricity generation via strengthening superoxide radical by using a novel 3D AQS/PPy-GF cathode.

    Science.gov (United States)

    Zhang, Yan; Li, Jinhua; Bai, Jing; Li, Linsen; Xia, Ligang; Chen, Shuai; Zhou, Baoxue

    2017-08-24

    A dramatic enhancement of organics degradation and electricity generation has been achieved in a wastewater fuel cell (WFC) system via strengthening superoxide radical with radical chain reaction by using a novel 3D anthraquinone/polypyrrole modified graphite felt (AQS/PPy-GF) cathode. The AQS/PPy-GF was synthesized by one-pot electrochemical polymerization method and used to in-situ generate superoxide radical by reducing oxygen under self-imposed electric field. Results showed that methyl orange (MO) were effectively degraded in AQS/PPy-GF/Fe(2+) system with a high apparent rate constant (0.0677 min(-1)), which was 3.9 times that (0.0174 min(-1)) in the Pt/Fe(2+) system and even 9.4 times that (0.0072 min(-1)) in the traditional WFC system (without Fe(2+)). Meanwhile, it showed a superior performance for electricity generation and the maximum power density output (1.130 mW cm(-2)) was nearly 3.3 times and 5.0 times higher, respectively, when compared with the Pt/Fe(2+) system and traditional WFC. This dramatic advance was attributed to 3D AQS/PPy-GF cathode which produces more O2(-) via one-electron reduction process. The presence of O2(-) cannot only directly contribute to MO degradation, but also promotes the final complete mineralization by turning itself to OH. Additionally, O2(-) accelerates the Fe(2+)/Fe(3+) couple cycling, thus avoiding continuous addition of any external ferrous ions. Inhibition and probe studies were conducted to ascertain the role of several radicals (OH and O2(-)) on the MO degradation. Superoxide radicals were considered as the primary reactive oxidants, and the degradation mechanism of MO was proposed. The proposed WFC system provides a more economical and efficient way for energy recovery and wastewater treatment. Copyright © 2017. Published by Elsevier Ltd.

  7. BPA-toxicity via superoxide anion overload and a deficit in β-catenin signaling in human bone mesenchymal stem cells.

    Science.gov (United States)

    Leem, Yea-Hyun; Oh, Seikwan; Kang, Hong-Je; Kim, Jung-Hwa; Yoon, Juno; Chang, Jae-Suk

    2017-01-01

    Bisphenol A (BPA), used in the manufacture of products based on polycarbonate plastics and epoxy resins, is well known as an endocrine-disrupting monomer. In the current study, BPA increased cytotoxicity in hBMSCs in a dose- and time-dependent manner, concomitantly with increased lipid peroxidation. Increased cell death in BPA-treated cells was markedly blocked by pretreatment with the superoxide dismutase mimetic MnTBAP and MnTMPyP, but not by catalase, glutathione, the glutathione peroxidase mimetic ebselen, the NOS inhibitor NAME, or the xanthine oxidase inhibitor allopurinol. Furthermore, the decline in nuclear β-catenin and cyclin D1 levels in hBMSCs exposed to BPA was reversed by MnTBAP treatment. Finally, treatment of hBMSCs with the GSK3β inhibitor LiCl2 increased nuclear β-catenin levels and significantly attenuated cytotoxicity compared with BPA treatment. Our current results in hBMSCs exposed to BPA suggest that BPA causes a disturbance in β-catenin signaling via a superoxide anion overload. © 2016 The Authors Environmental Toxicology Published by Wiley Periodicals, Inc. Environ Toxicol 32: 344-352, 2017.

  8. An Azobenzenyl Anion Radical Complex of Magnesium: Synthesis, Structure, and Reactivity Studies.

    Science.gov (United States)

    Ren, Wenshan; Gu, Defa

    2016-11-21

    Azobenzenyl anion radical complex of magnesium [HC(C(Me)N-2,6-(i)Pr2C6H3)2]Mg(PhNNPh) (THF) (2) was obtained for the first time through the reaction of [HC(C(Me)N-2,6-(i)Pr2C6H3)2]MgBr (1) with potassium graphite in the presence of azobenzene. Complex 2 is a useful electron-transfer reagent as shown by the reactivity with diphenyl disulfide, diphenyl diselenide, oxygen, sulfur, and Me3SiN3 yielding the magnesium thiolate [HC(C(Me)N-2,6-(i)Pr2C6H3)2]Mg(SPh)(THF) (3), magnesium selenolate [HC(C(Me)N-2,6-(i)Pr2C6H3)2]Mg(SePh)(THF) (4), peroxido complex {[HC(C(Me)N-2,6-(i)Pr2C6H3)2]Mg(THF)}2(μ-η(2)-η(2)-O2) (5), persulfido complex {[HC(C(Me)N-2,6-(i)Pr2C6H3)2]Mg(THF)}2(μ-η(2)-η(2)-S2) (6), and azido complex [HC(C(Me)N-2,6-(i)Pr2C6H3)2]MgN3 (7), respectively. Furthermore, treatment of 2 with Me3SiCHN2 results in a rearrangement product {[HC(C(Me)N-2,6-(i)Pr2C6H3)2]Mg[CNN(SiMe3)]}2 (8).

  9. Pyridoxine and pyridoxamine inhibits superoxide radicals and prevents lipid peroxidation, protein glycosylation, and (Na+ + K+)-ATPase activity reduction in high glucose-treated human erythrocytes.

    Science.gov (United States)

    Jain, S K; Lim, G

    2001-02-01

    Vitamin B(6) (pyridoxine) supplementation has been found beneficial in preventing diabetic neuropathy and retinopathy, and the glycosylation of proteins. Oxygen radicals and oxidative damage have been implicated in the cellular dysfunction and complications of diabetes. This study was undertaken to test the hypothesis that pyridoxine (P) and pyridoxamine (PM) inhibit superoxide radical production, reduce lipid peroxidation and glycosylation, and increase the (Na+ + K+)-ATPase activity in high glucose-exposed red blood cells (RBC). Superoxide radical production was assessed by the reduction of cytochrome C by glucose in the presence and absence of P or PM in a cell-free buffered solution. To examine cellular effects, washed normal human RBC were treated with control and high glucose concentrations with and without P or PM. Both P and PM significantly lowered lipid peroxidation and glycated hemoglobin (HbA(1)) formation in high glucose-exposed RBC. P and PM significantly prevented the reduction in (Na+ + K+)-ATPase activity in high glucose-treated RBC. Thus, P or PM can inhibit oxygen radical production, which in turn prevents the lipid peroxidation, protein glycosylation, and (Na+ + K+)-ATPase activity reduction induced by the hyperglycemia. This study describes a new biochemical mechanism by which P or PM supplementation may delay or inhibit the development of complications in diabetes.

  10. Synergism between arsenite and proteasome inhibitor MG132 over cell death in myeloid leukaemic cells U937 and the induction of low levels of intracellular superoxide anion

    Energy Technology Data Exchange (ETDEWEB)

    Lombardo, Tomás [Laboratorio de Immunotoxicologia (LaITO), IDEHU-CONICET, Hospital de Clínicas, José de San Martín, Universidad de Buenos Aires (UBA), Buenos Aires (Argentina); Cavaliere, Victoria; Costantino, Susana N. [Laboratorio de Inmunología Tumoral (LIT), IDEHU-CONICET, Facultad de Farmacia y Bioquímica, UBA, Buenos Aires (Argentina); Kornblihtt, Laura [Servicio de Hematología, Hospital de Clínicas, José de San Martín (UBA), Buenos Aires (Argentina); Alvarez, Elida M. [Laboratorio de Inmunología Tumoral (LIT), IDEHU-CONICET, Facultad de Farmacia y Bioquímica, UBA, Buenos Aires (Argentina); Blanco, Guillermo A., E-mail: gblanco@ffyb.uba.ar [Laboratorio de Immunotoxicologia (LaITO), IDEHU-CONICET, Hospital de Clínicas, José de San Martín, Universidad de Buenos Aires (UBA), Buenos Aires (Argentina)

    2012-02-01

    Increased oxygen species production has often been cited as a mechanism determining synergism on cell death and growth inhibition effects of arsenic-combined drugs. However the net effect of drug combination may not be easily anticipated solely from available knowledge of drug-induced death mechanisms. We evaluated the combined effect of sodium arsenite with the proteasome inhibitor MG132, and the anti-leukaemic agent CAPE, on growth-inhibition and cell death effect in acute myeloid leukaemic cells U937 and Burkitt's lymphoma-derived Raji cells, by the Chou–Talalay method. In addition we explored the association of cytotoxic effect of drugs with changes in intracellular superoxide anion (O{sub 2}{sup −}) levels. Our results showed that combined arsenite + MG132 produced low levels of O{sub 2}{sup −} at 6 h and 24 h after exposure and were synergic on cell death induction in U937 cells over the whole dose range, although the combination was antagonistic on growth inhibition effect. Exposure to a constant non-cytotoxic dose of 80 μM hydrogen peroxide together with arsenite + MG132 changed synergism on cell death to antagonism at all effect levels while increasing O{sub 2}{sup −} levels. Arsenite + hydrogen peroxide also resulted in antagonism with increased O{sub 2}{sup −} levels in U937 cells. In Raji cells, arsenite + MG132 also produced low levels of O{sub 2}{sup −} at 6 h and 24 h but resulted in antagonism on cell death and growth inhibition. By contrast, the combination arsenite + CAPE showed high levels of O{sub 2}{sup −} production at 6 h and 24 h post exposure but resulted in antagonism over cell death and growth inhibition effects in U937 and Raji cells. We conclude that synergism between arsenite and MG132 in U937 cells is negatively associated to O{sub 2}{sup −} levels at early time points after exposure. -- Highlights: ► Arsenic combined cytotoxic and anti-proliferative effects by Chou–Talalay method. ► Cytotoxic effect

  11. Anion size control of the packing in the metallic versus semiconducting chiral radical cation salts (DM-EDT-TTF)2XF6 (X = P, As, Sb).

    Science.gov (United States)

    Pop, Flavia; Auban-Senzier, Pascale; Canadell, Enric; Avarvari, Narcis

    2016-10-13

    Control of the structural type in metallic enantiopure and racemic radical cation salts is achieved through hydrogen bonding interactions between the chiral donor DM-EDT-TTF and the XF6 anions (X = P, As, Sb), determined by the anion size and the chiral information.

  12. Hydration Leads to Efficient Reactions of the Carbonate Radical Anion with Hydrogen Chloride in the Gas Phase.

    Science.gov (United States)

    Tang, Wai Kit; van der Linde, Christian; Siu, Chi-Kit; Beyer, Martin K

    2017-01-12

    The carbonate radical anion CO3(•-) is a key intermediate in tropospheric anion chemistry. Despite its radical character, only a small number of reactions have been reported in the literature. Here we investigate the gas-phase reactions of CO3(•-) and CO3(•-)(H2O) with HCl under ultrahigh vacuum conditions. Bare CO3(•-) forms OHCl(•-) with a rate constant of 4.2 × 10(-12) cm(3) s(-1), which corresponds to an efficiency of only 0.4%. Hydration accelerates the reaction, and ligand exchange of H2O against HCl proceeds with a rate of 2.7 × 10(-10) cm(3) s(-1). Quantum chemical calculations reveal that OHCl(•-) is best described as an OH(•) hydrogen bonded to Cl(-), while the ligand exchange product is Cl(-)(HCO3(•)). Under tropospheric conditions, where CO3(•-)(H2O) is the dominant species, Cl(-)(HCO3(•)) is efficiently formed. These reactions must be included in models of tropospheric anion chemistry.

  13. Utilizing of 1-Hexyl-1-Methyl-Pyrrolidinium Bis (Trifluoromethyl-Sulfonyl Imide as Medium for Electrochemical Generation of Superoxide Ion-Radical

    Directory of Open Access Journals (Sweden)

    Maan Hayyan

    2011-12-01

    Full Text Available The superoxide ion-radical was generated and analysed electrochemically using cyclic voltammetry (CV technique from oxygen dissolved in a room-temperature ionic liquid, 1-Hexyl-1-methyl-pyrrolidinium bis (trifluoromethylsulfonyl imide, at atmospheric pressure. It was found that the generated superoxide ion was stable which indicates its possible use for further useful applications.ABSTRAK: Ion radikal superoksida dihasil dan dianalisa secara elektrokimia menggunakan teknik voltammetri berkitar (cyclic voltammetry (CV daripada oksigen yang dilarutkan dalam larutan ionik pada suhu bilik, 1-Hexyl-1-methyl-pyrrolidinium bis (trifluoromethylsulfonyl imida, pada tekanan atmosfera. Didapati bahawa ion superoksida yang terhasil adalah stabil. Ini menunjukkan ia berkemungkinan berguna dalam aplikasi lain.

  14. Formation and decay of fluorobenzene radical anions affected by their isomeric structures and the number of fluorine atoms.

    Science.gov (United States)

    Higashino, Saki; Saeki, Akinori; Okamoto, Kazumasa; Tagawa, Seiichi; Kozawa, Takahiro

    2010-08-12

    Aryl fluoride has attracted much attention as a resist component for extreme ultraviolet (EUV) lithography, because of the high absorption cross section of fluorine for EUV photons; however, less is known about electron attachment to fluorobenzene (FBz) and the stability of the reduced state. Picosecond and nanosecond pulse radiolysis of tetrahydrofuran solutions of FBz from mono-, di-, tri-, tetra-, penta-, and hexafluorobenzene was performed, and the effects of isomeric structure and number of fluorine atoms were examined. Scavenging of solvated electrons was found to correlate with the electron affinity obtained by density functional theory in the gas phase, whereas the decay of FBz radical anions was dominated by the activation energy of fluorine anion dissociation calculated using a polarized continuum model (PCM). A sharp contrast in the lifetimes of ortho-, meta-, and para-position difluorobenzene was observed, which could provide information on the molecular design of functional materials.

  15. Chloride anion effect on the advanced oxidation processes of methidathion and dimethoate: role of Cl2(·-) radical.

    Science.gov (United States)

    Caregnato, Paula; Rosso, Janina A; Soler, Juán M; Arques, Antonio; Mártire, Daniel O; Gonzalez, Mónica C

    2013-01-01

    The reaction of phosphor-containing pesticides such as methidathion (MT) and dimethoate (DM) with dichloride radical anions (Cl(2)(·-)) was investigated. The second order rate constants (1.3 ± 0.4) × 10(8) and (1.1 ± 0.4) × 10(8) M(-1) s(-1) were determined for the reaction of Cl(2)(·-) with MT and DM, respectively. A reaction mechanism involving an initial charge transfer from the sulfide groups of the insecticides to Cl(2)(·-) is proposed and supported by the identified transient intermediates and reaction products. The formation of chlorinated byproducts was determined. The unexpected consequences of an efficient Cl(2)(·-) reactivity towards MT and DM on the degradation capacity by Advanced Oxidation Procedures applied to polluted waters containing the insecticides and Cl(-) anions is discussed.

  16. Spin adducts of several N-2-(2-alkoxycarbonyl-propyl)-alpha-pyridylnitrone derivatives with superoxide, alkyl and lipid-derived radicals.

    Science.gov (United States)

    Stolze, Klaus; Udilova, Natascha; Rosenau, Thomas; Hofinger, Andreas; Nohl, Hans

    2004-07-01

    Several derivatives of N-t-butyl-alpha-phenylnitrone (PBN) such as N-2-(2-ethoxycarbonyl-propyl)-alpha-phenylnitrone (EPPN) have recently been reported to form superoxide spin adducts (t(1/2) ca. 2-7 min at pH 7.0), which are considerably more stable than their respective PBN or DMPO adducts (t(1/2) ca. 10 and 45 s, respectively). In continuation of our studies on structure optimization of EPPN derivatives, a series of 12 novel spin traps with 2-, 3- and 4-pyridinyl substituents was synthesized and fully characterized by 1H NMR, 13C NMR and IR spectroscopy. In addition to the replacement of the phenyl ring by a 2-, 3- or 4-pyridinyl substituent, the ethoxy group of the parent compound EPPN was replaced by either a propoxy, iso-propoxy, or cyclopropylmethoxy moiety. Superoxide adducts of all PPyN derivatives were considerably more stable than those of the respective EPPN derivatives with half-lives ranging from about 6 to 11 min. In addition, alkoxyl radical adducts were also considerably more stable than those of the EPPN series. Hydroxyl radical adducts were not detected, on the other hand, very stable spin adducts were formed from a series of carbon centered radicals, e.g. from the methyl or hydroxymethyl radical. The novel spin traps are offering an alternative to PBN or POBN, especially where the higher stability of oxygen-centered radical adducts is of major importance. All of them can easily be synthesized from commercially available compounds in two or three steps.

  17. Proton transfer from water to ketyl radical anion: Assessment of critical size of hydrated cluster and free energy barrier in solution from first principles simulations

    Science.gov (United States)

    Biswas, Sohag; Dasgupta, Teesta; Mallik, Bhabani S.

    2016-09-01

    We present the reactivity of an organic intermediate by studying the proton transfer process from water to ketyl radical anion using gas phase electronic structure calculations and the metadynamics method based first principles molecular dynamics (FPMD) simulations. Our results indicate that during the micro solvation of anion by water molecules systematically, the presence of minimum three water molecules in the gas phase cluster is sufficient to observe the proton transfer event. The analysis of trajectories obtained from initial FPMD simulation of an aqueous solution of the anion does not show any evident of complete transfer of the proton from water. The cooperativity of water molecules and the relatively weak anion-water interaction in liquid state prohibit the full release of the proton. Using biasing potential through first principles metadynamics simulations, we report the observation of proton transfer reaction from water to ketyl radical anion with a barrier height of 16.0 kJ/mol.

  18. Aqueous-Phase Reactions of Isoprene with Sulfoxy Radical Anions as a way of Wet Aerosol Formation in the Atmosphere

    Science.gov (United States)

    Kuznietsova, I.; Rudzinski, K. J.; Szmigielski, R.; Laboratory of the Environmental Chemistry

    2011-12-01

    Atmospheric aerosols exhibit an important role in the environment. They have implications on human health and life, and - in the larger scale - on climate, the Earth's radiative balance and the cloud's formation. Organic matter makes up a significant fraction of atmospheric aerosols (~35% to ~90%) and may originate from direct emissions (primary organic aerosol, POA) or result from complex physico-chemical processes of volatile organic compounds (secondary organic aerosol, SOA). Isoprene (2-methyl-buta-1,3-diene) is one of the relevant volatile precursor of ambient SOA in the atmosphere. It is the most abundant non-methane hydrocarbon emitted to the atmosphere as a result of living vegetation. According to the recent data, the isoprene emission rate is estimated to be at the level of 500 TgC per year. While heterogeneous transformations of isoprene have been well documented, aqueous-phase reactions of this hydrocarbon with radical species that lead to the production of new class of wet SOA components such as polyols and their sulfate esters (organosulfates), are still poorly recognized. The chain reactions of isoprene with sulfoxy radical-anions (SRA) are one of the recently researched route leading to the formation of organosulfates in the aqueous phase. The letter radical species originate from the auto-oxidation of sulfur dioxide in the aqueous phase and are behind the phenomenon of atmospheric acid rain formation. This is a complicated chain reaction that is catalyzed by transition metal ions, such as manganese(II), iron(III) and propagated by sulfoxy radical anions . The presented work addresses the chemical interaction of isoprene with sulfoxy radical-anions in the water solution in the presence of nitrite ions and nitrous acid, which are important trace components of the atmosphere. We showed that nitrite ions and nitrous acid significantly altered the kinetics of the auto-oxidation of SO2 in the presence of isoprene at different solution acidity from 2 to 8

  19. Secondary analysis of publicly available data reveals superoxide and oxygen radical pathways are enriched for associations between type 2 diabetes and low-frequency variants.

    Science.gov (United States)

    Yazdanpanah, Mojgan; Chen, Chuhua; Graham, Jinko

    2013-11-01

    Genome-wide association studies explain at most 5%-10% of the heritable components of type 2 diabetes. Some of the "missing type 2 diabetes heritability" could be explained by low-frequency variants. We examined the associations between low-frequency variants and type 2 diabetes, using data from 2538 diabetic and 2977 nondiabetic subjects in the publicly available database of Genotypes and Phenotypes. We applied two approaches. First, we combined information from all low-frequency (1%-5%) variants at a locus in a gene-centric analysis of associations with diabetes. Next, we searched for gene ontology (GO) biological processes that were enriched for gene-centric associations, after correcting for multiple testing to control the false discovery rate (FDR). We found three GO biological processes that were significantly enriched for associations to diabetes: "response to superoxide" (FDR-adjusted p=2.7×10(-3)), "response to oxygen radical" (FDR-adjusted p=2.7×10(-3)), and "heart contraction" (FDR-adjusted p=2.6×10(-2)). There were three genes that contributed to "response to superoxide" and "oxygen radical" pathways, including the SOD1 gene. Gene-centric tests of association with low-frequency variants, followed by analysis to evaluate which biological pathways are enriched for these associations has the potential to recover, at least some proportion of, the "missing heritability" of type 2 diabetes.

  20. Reactions of isoprene and sulphoxy radical-anions – a possible source of atmospheric organosulphites and organosulphates

    Directory of Open Access Journals (Sweden)

    K. J. Rudziński

    2009-03-01

    Full Text Available Transformation of isoprene coupled with auto-oxidation of SIV in aqueous solutions was studied experimentally and by chemical-kinetic modelling over a 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 auto-oxidation 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=163, sulphurous acid mono-(4-hydroxy-2-methyl-but-2-enyl ester (m/z=165, sulphuric acid mono-(2-methyl-4-oxo-but-2-enyl ester (m/z=179, sulphuric acid mono-(4-hydroxy-2-methyl-but-2-enyl ester (m/z=181, and possible structural isomers of these species – was indicated by electrospray ionisation mass spectrometric analysis of post-reaction mixtures. The experimental results 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 radical-anions by isoprene, the formation of sulphoxy radical-anions during further reactions of isoprene radicals, and the auto-oxidation of SIV itself. A chemical mechanism based on this idea was explored numerically to show good agreement with experimental data. In basic and neutral solutions, the model overestimated the consumption of isoprene, probably because reactions of primary sulphite and sulphate derivatives of isoprene with sulphoxy radical-anions were not included. Interaction of isoprene with sulphur(IV species and oxygen can possibly result in formation of new organosulphate and organosulphite components of atmospheric aerosols and waters, and

  1. Superoxide Mediates the Toxicity of Paraquat for Chinese Hamster Ovary Cells

    Science.gov (United States)

    Bagley, Ann C.; Krall, Judith; Lynch, Robert E.

    1986-05-01

    The roles of superoxide and H2O2 in the cytotoxicity of paraquat were assessed in Chinese hamster ovary cells. Neither catalase nor superoxide dismutase inhibited the loss of ability to form colonies when added to the medium. When introduced into the cells, superoxide dismutase but not catalase inhibited the toxicity of paraquat. That superoxide dismutase acted by its known catalytic action is shown by the loss of inhibition when the enzyme was inactivated by H2O2 before being introduced into the cells. The lack of inhibition by catalase, by dimethyl sulfoxide, and by desferoxamine suggests that the toxicity is not mediated by a reaction between H2O2 and superoxide to engender the hydroxyl radical. Exposure of Chinese hamster ovary cells to paraquat may be a suitable means to determine the effects of superoxide anion in cultured cells and the ways in which cells can resist this toxic action.

  2. Polyimido sulphur anions S(NR)$^{m-}_{n}$: Free radicals and coordination behaviour

    Indian Academy of Sciences (India)

    Dietmar Stalke

    2000-06-01

    In a reaction sequence of amide addition followed by halogen oxidation the triazasulphite S(NR)$^{2-}_{3}$ and the tetrazasulphate S(NR)$^{2-}_{4}$ are readily accessible from sulphur diimide S(NR)2 via sulphur triimide S(NR)3. Addition of lithium organics to sulphur triimide provides a general route to triazasulphonates RS(NR)$^{2-}_{3}$. All these anions resemble potential tripodal coordination behaviour because of their nitrogen donor centres. Furthermore, the sulphur polyimido ligands are capable of responding to the various requirements of different metals (even in mixed metal species) by charge (de)localization. This paper deals with the synthetic routes of the sulphur nitrogen anions and their coordination behaviour. Their reactivity, mainly towards main group metal synthons, is also discussed.

  3. Nitro radical anions from megazol and related nitroimidazoles in aprotic media. A father-son type reaction triggered by an acidic proton

    Energy Technology Data Exchange (ETDEWEB)

    Bonta, M.; Chauviere, G.; Perie, J.; Nunez-Vergara, L.J.; Squella, J.A

    2002-09-25

    We have studied the electrochemical reduction of some nitroimidazoles such as megazol(2-amino-5-(1-methyl-5-nitro-2-imidazolyl)-1,3,4-thiadiazol, CAS 19622-55-0) and two related derivatives in aprotic media (100% DMF, 0.1 M TBAP). All the studied compounds were easily reducible in aprotic media generating the corresponding nitro radical anions as products of the one electron reduction of the parent compound. The nitro radical anions decay by a dimerization reaction and the dimerization rate constants were obtained according to the Olmstead's approach by obtaining values of 150{+-}24, 1690{+-}42 and 640{+-}32 M{sup -1} s{sup -1} for megazol, GC-361 and GC-284, respectively. The existence of an acidic proton on the acetamide group in the GC-361 molecule triggered the appearance of father-son type reactions between the nitro radical anion from GC-361 (son compound) and GC-361 (father compound) generating the neutral radical and the conjugate base of GC-361. Thus the nitro radical anion from GC-361 acts as a Broensted base abstracting the proton of the acetamide group in the GC-361 derivative of megazol.

  4. N-acetylcysteine downregulates phosphorylated p-38 expression but does not reverse the increased superoxide anion levels in the spinal cord of rats with neuropathic pain.

    Science.gov (United States)

    Horst, A; de Souza, J A; Santos, M C Q; Riffel, A P K; Kolberg, C; Ribeiro, M F M; de Fraga, L S; Partata, W A

    2017-02-16

    We determined the effect of N-acetylcysteine (NAC) on the expression of the phosphorylated p38 (p-p38) protein and superoxide anion generation (SAG), two important players in the processing of neuropathic pain, in the lumbosacral spinal cord of rats with chronic constriction injury (CCI)-induced neuropathic pain. The sciatic functional index (SFI) was also measured to assess the functional recovery post-nerve lesion. Thirty-six male Wistar rats were divided equally into the following groups: Naive (rats did not undergo surgical manipulation); Sham (rats in which all surgical procedures involved in CCI were used except the ligature), and CCI (rats in which four ligatures were tied loosely around the right common sciatic nerve), which received 2, 4, or 8 intraperitoneal injections of NAC (150 mg·kg-1·day-1) or saline beginning 4 h after CCI. Rats were sacrificed 1, 3, and 7 days after CCI. The SFI was measured on these days and the lumbosacral spinal cord was used for analysis of p-p38 expression and SAG. CCI induced a decrease in SFI as well as an increase in p-p38 expression and SAG in the spinal cord. The SFI showed a partial recovery at day 7 in saline-treated CCI rats, but recovery was improved in NAC-treated CCI rats. NAC induced a downregulation in p-p38 expression at all time-points evaluated, but did not reverse the increased SAG induced by CCI. Since p-p38 is a mediator in neuropathic pain and/or nerve regeneration, modulation of this protein may play a role in NAC-induced effects in CCI rats.

  5. Inhibition of glutamate receptors reduces the homocysteine-induced whole blood platelet aggregation but does not affect superoxide anion generation or platelet membrane fluidization.

    Science.gov (United States)

    Karolczak, Kamil; Pieniazek, Anna; Watala, Cezary

    2017-01-01

    Homocysteine (Hcy) is an excitotoxic amino acid. It is potentially possible to prevent Hcy-induced toxicity, including haemostatic impairments, by antagonizing glutaminergic receptors. Using impedance aggregometry with arachidonate and collagen as platelet agonists, we tested whether the blockade of platelet NMDA (N-methyl-D-aspartate), AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) and kainate receptors with their inhibitors: MK-801 (dizocilpine hydrogen maleate, [5R,10S]-[+]-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine), CNQX (7-nitro-2,3-dioxo-1,4-dihydroquinoxaline-6-carbonitrile) and UBP-302 (2-{[3-[(2S)-2-amino-2-carboxyethyl]-2,6-dioxo-3,6-dihydropyrimidin 1(2H)-yl]methyl}benzoic acid) may hamper Hcy-dependent platelet aggregation. All the tested compounds significantly inhibited Hcy-augmented aggregation of blood platelets stimulated either with arachidonate or collagen. Hcy stimulated the generation of superoxide anion in whole blood samples in a concentration-dependent manner; however, this process appeared as independent on ionotropic glutamate receptors, as well as on NADPH oxidase and protein kinase C, and was not apparently associated with the extent of either arachidonate- or collagen-dependent platelet aggregation. Moreover, Hcy acted as a significant fluidizer of surface (more hydrophilic) and inner (more hydrophobic) regions of platelet membrane lipid bilayer, when used at the concentration range from 10 to 50 µmol/l. However, this effect was independent on the Hcy action through glutamate ionotropic receptors, since there was no effects of MK-801, CNQX or UBP-302 on Hcy-mediated membrane fluidization. In conclusion, Hcy-induced changes in whole blood platelet aggregation are mediated through the ionotopic excitotoxic receptors, although the detailed mechanisms underlying such interactions remain to be elucidated.

  6. Acute ethanol intake induces superoxide anion generation and mitogen-activated protein kinase phosphorylation in rat aorta: A role for angiotensin type 1 receptor

    Energy Technology Data Exchange (ETDEWEB)

    Yogi, Alvaro; Callera, Glaucia E. [Kidney Research Centre, Ottawa Hospital Research Institute, University of Ottawa, Ontario (Canada); Mecawi, André S. [Department of Physiology, Faculty of Medicine of Ribeirão Preto, University of São Paulo (USP), Ribeirão Preto, SP (Brazil); Batalhão, Marcelo E.; Carnio, Evelin C. [Department of General and Specialized Nursing, College of Nursing of Ribeirão Preto, USP, São Paulo (Brazil); Antunes-Rodrigues, José [Department of Physiology, Faculty of Medicine of Ribeirão Preto, University of São Paulo (USP), Ribeirão Preto, SP (Brazil); Queiroz, Regina H. [Department of Clinical, Toxicological and Food Science Analysis, Faculty of Pharmaceutical Sciences, USP, São Paulo (Brazil); Touyz, Rhian M. [Kidney Research Centre, Ottawa Hospital Research Institute, University of Ottawa, Ontario (Canada); Tirapelli, Carlos R., E-mail: crtirapelli@eerp.usp.br [Department of Psychiatric Nursing and Human Sciences, Laboratory of Pharmacology, College of Nursing of Ribeirão Preto, USP, Ribeirão Preto, SP (Brazil)

    2012-11-01

    Ethanol intake is associated with increase in blood pressure, through unknown mechanisms. We hypothesized that acute ethanol intake enhances vascular oxidative stress and induces vascular dysfunction through renin–angiotensin system (RAS) activation. Ethanol (1 g/kg; p.o. gavage) effects were assessed within 30 min in male Wistar rats. The transient decrease in blood pressure induced by ethanol was not affected by the previous administration of losartan (10 mg/kg; p.o. gavage), a selective AT{sub 1} receptor antagonist. Acute ethanol intake increased plasma renin activity (PRA), angiotensin converting enzyme (ACE) activity, plasma angiotensin I (ANG I) and angiotensin II (ANG II) levels. Ethanol induced systemic and vascular oxidative stress, evidenced by increased plasma thiobarbituric acid-reacting substances (TBARS) levels, NAD(P)H oxidase‐mediated vascular generation of superoxide anion and p47phox translocation (cytosol to membrane). These effects were prevented by losartan. Isolated aortas from ethanol-treated rats displayed increased p38MAPK and SAPK/JNK phosphorylation. Losartan inhibited ethanol-induced increase in the phosphorylation of these kinases. Ethanol intake decreased acetylcholine-induced relaxation and increased phenylephrine-induced contraction in endothelium-intact aortas. Ethanol significantly decreased plasma and aortic nitrate levels. These changes in vascular reactivity and in the end product of endogenous nitric oxide metabolism were not affected by losartan. Our study provides novel evidence that acute ethanol intake stimulates RAS activity and induces vascular oxidative stress and redox-signaling activation through AT{sub 1}-dependent mechanisms. These findings highlight the importance of RAS in acute ethanol-induced oxidative damage. -- Highlights: ► Acute ethanol intake stimulates RAS activity and vascular oxidative stress. ► RAS plays a role in acute ethanol-induced oxidative damage via AT{sub 1} receptor activation.

  7. The Protective Effects of N-Acetylcysteine on Exogenous Hydrogen Peroxide and Endogenous Superoxide Anion induced DNA Strand Breakage in Human Spermatozoa%`

    Institute of Scientific and Technical Information of China (English)

    徐德祥; 沈汉民; 王俊南

    2001-01-01

    Objective To explore the protective effects of N-Acetylcysteine (NAC) on exogenous hydrogen peroxide and endogenous superoxide anion-induced DNA strand breakage in human spermatozoa by using the single-cell gel electropherosis (SCGE)Methods Sperm cells were exposed to 0. 5 mmol/L of H2O2 or 5. 0 mmol/L of β -NADPH with or without 0. 1, 0. 5, 1. 0 mmol/L of NAC. The percentage of sperm comet cells and the comet tail lengths were measured in the treated sperm cells by using SCGE.Results Both percentage of comet sperm nuclei and mean tail length in sperm cells exposed to 0. 5 mmol/L hydrogen peroxide with different concentrations of NAC decrease significantly in a dose-dependent manner as compared with sperm cells exposed to H2O2 without NAC or catalase. Although mean tail length in sperm cells exposed to 5. 0 mmol/L of β-NADPH with different concentrations of NAC decreases significantly compared with sperm cells exposed to β-NADPH without NAC or SOD,there were no significant differences on the percentage of sperm comet cells between sperm cells exposed to 5. 0 mmol/L of β-NADPH with different concentrations of NAC and sperm cells exposed to 5. 0 mmol/L of β-NADPH without NAC.Conclusion NAC has a protective effect on exogenous hydrogen peroxide-induced DNA damage, while protective effect of NAC against O2- induced DNA strand break age is significant but very weak.

  8. Theoretical and experimental studies of the spin trapping of inorganic radicals by 5,5-dimethyl-1-pyrroline N-oxide (DMPO). 1. Carbon dioxide radical anion.

    Science.gov (United States)

    Villamena, Frederick A; Locigno, Edward J; Rockenbauer, Antal; Hadad, Christopher M; Zweier, Jay L

    2006-12-14

    The carbon dioxide radical anion (CO2*-) is known to be generated in vivo through various chemical and biochemical pathways. Electron paramagnetic resonance (EPR) spin trapping with the commonly used spin trap, 5,5-dimethyl-1-pyrroline N-oxide (DMPO), has been employed in the detection of CO2*-. The thermodynamics of CO2*- addition to DMPO was predicted using density functional theory (DFT) at the B3LYP/6-31++G**//B3LYP/6-31G* and B3LYP/6-311+G* levels with the polarizable continuum model (PCM) to simulate the effect of the bulk dielectric effect of water on the calculated energetics. Three possible products of CO2*- addition to DMPO were predicted: (1) a carboxylate adduct, (2) pyrroline-alcohol and (3) DMPO-OH. Experimentally, UV photolysis of H2O2 in the presence of sodium formate (NaHCO2) and DMPO gave an EPR spectrum characteristic of a C-centered carboxylate adduct and is consistent with the theoretically derived hyperfine coupling constants (hfcc). The pKa of the carboxylate adduct was estimated computationally to be 6.4. The mode of CO2*- addition to DMPO is predicted to be governed predominantly by the spin (density) population on the radical, whereas electrostatic effects are not the dominant factor for the formation of the persistent adduct. The thermodynamic behavior of CO2*- in the aqueous phase is predicted to be similar to that of mercapto radical (*SH), indicating that formation of CO2*- in biological systems may have an important role in the initiation of oxidative damage in cells.

  9. Electron Impact Ionization/Dissociation of Molecules: Production of Energetic Radical Ions and Anions

    Energy Technology Data Exchange (ETDEWEB)

    Feil, S [Institut fuer Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Technikerstr.25, A-6020 Innsbruck (Austria); Sulzer, P [Institut fuer Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Technikerstr.25, A-6020 Innsbruck (Austria); Mauracher, A [Institut fuer Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Technikerstr.25, A-6020 Innsbruck (Austria); Beikircher, M [Institut fuer Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Technikerstr.25, A-6020 Innsbruck (Austria); Wendt, N [Institut fuer Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Technikerstr.25, A-6020 Innsbruck (Austria); Aleem, A [Institut fuer Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Technikerstr.25, A-6020 Innsbruck (Austria); Denifl, S [Institut fuer Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Technikerstr.25, A-6020 Innsbruck (Austria); Zappa, F [Institut fuer Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Technikerstr.25, A-6020 Innsbruck (Austria); Matt-Leubner, S [Institut fuer Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Technikerstr.25, A-6020 Innsbruck (Austria); Bacher, A [Institut fuer Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Technikerstr.25, A-6020 Innsbruck (Austria); Matejcik, S [Department of Experimental Physics, Comenius University, SK-84248 Bratislava, Slovak Republic (Slovakia); Probst, M [Institut fuer Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Technikerstr.25, A-6020 Innsbruck (Austria); Scheier, P [Institut fuer Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Technikerstr.25, A-6020 Innsbruck (Austria); Maerk, T D [Institut fuer Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Technikerstr.25, A-6020 Innsbruck (Austria)

    2007-10-15

    In order to provide quantitative information on electron collision processes involving various plasma constituents (in particular hydrocarbons) and to elucidate the properties of cations and anions produced we have carried out the past years a series of studies with a variety of techniques in our laboratory in Innsbruck. In the present review we will present some recent results on electron impact ionization and attachment in order to illustrate recent progress in this field in particular concerning the production of energetic fragment cations for hydrocarbons and differences in the attachment of isomers for nitro-organics. Using a Nier type electron impact ion source in combination with a double focusing two sector field mass spectrometer, partial cross sections for electron impact ionization of acetylene, propene and other hydrocarbons have been measured for electron energies up to 1000 eV. Discrimination factors for ions have been determined using the deflection field method in combination with a three-dimensional ion trajectory simulation of ions produced in the ion source. Analysis of the ion yield curves obtained by scanning the deflectors allows the assignment of ions with the same mass-to-charge ratio to specific production channels on the basis of their different kinetic energy distributions. This analysis also allows to determine, besides kinetic energy distributions of fragment ions, partial cross sections differential in kinetic energy. Moreover charge separation reactions (for instance in case of acetylene the Coulomb explosion of the doubly-charged parent ions C{sub 2}H{sub 2}{sup ++} into the fragment ions C{sub 2}H{sup +} and H{sup +}) are investigated by means of a number of metastable mass spectrometry methods and the associated mean kinetic energy release is deduced. Free electron attachment to the three different isomers of mono-nitrotoluene molecules in the gas phase is studied using two different crossed electron-molecule beams technique. In

  10. Electron Impact Ionization/Dissociation of Molecules: Production of Energetic Radical Ions and Anions

    Science.gov (United States)

    Feil, S.; Sulzer, P.; Mauracher, A.; Beikircher, M.; Wendt, N.; Aleem, A.; Denifl, S.; Zappa, F.; Matt-Leubner, S.; Bacher, A.; Matejcik, S.; Probst, M.; Scheier, P.; Märk, T. D.

    2007-10-01

    In order to provide quantitative information on electron collision processes involving various plasma constituents (in particular hydrocarbons) and to elucidate the properties of cations and anions produced we have carried out the past years a series of studies with a variety of techniques in our laboratory in Innsbruck. In the present review we will present some recent results on electron impact ionization and attachment in order to illustrate recent progress in this field in particular concerning the production of energetic fragment cations for hydrocarbons and differences in the attachment of isomers for nitro-organics. Using a Nier type electron impact ion source in combination with a double focusing two sector field mass spectrometer, partial cross sections for electron impact ionization of acetylene, propene and other hydrocarbons have been measured for electron energies up to 1000 eV. Discrimination factors for ions have been determined using the deflection field method in combination with a three-dimensional ion trajectory simulation of ions produced in the ion source. Analysis of the ion yield curves obtained by scanning the deflectors allows the assignment of ions with the same mass-to-charge ratio to specific production channels on the basis of their different kinetic energy distributions. This analysis also allows to determine, besides kinetic energy distributions of fragment ions, partial cross sections differential in kinetic energy. Moreover charge separation reactions (for instance in case of acetylene the Coulomb explosion of the doubly-charged parent ions C2H2++ into the fragment ions C2H+ and H+) are investigated by means of a number of metastable mass spectrometry methods and the associated mean kinetic energy release is deduced. Free electron attachment to the three different isomers of mono-nitrotoluene molecules in the gas phase is studied using two different crossed electron-molecule beams technique. In contrast to previous studies for a

  11. Mechanistic aspects of the oxidative and reductive fragmentation of n-nitrosoamines: a new method for generating nitrenium cations, amide anions, and aminyl radicals

    OpenAIRE

    Piech, Krzysztof; Bally, Thomas; Sikora, Adam; Marcinek, Andrzej

    2008-01-01

    A new method for investigating the mechanisms of nitric oxide release from NO donors under oxidative and reductive conditions is presented. Based on the fragmentation of N-nitrosoamines, it allows generation and spectroscopic characterization of nitrenium cations, amide anions, and aminyl radicals. X-irradiation of N-nitroso-N,N-diphenylamine 1 in Ar matrices at 10 K is found to yield the corresponding radical ions, which apparently undergo spontaneous loss of NO° under the conditions of this...

  12. The formation and stability of the superoxide radical (O2-) on rock-forming minerals: Band gaps, hydroxylation state, and implications for Mars oxidant chemistry

    Science.gov (United States)

    Zent, Aaron P.; Ichimura, Andrew S.; Quinn, Richard C.; Harding, Heather K.

    2008-09-01

    We have examined the generation and stability of O2 - on TiO2 and albite, a common Na feldspar. We were not able to produce thermally stable superoxide on albite, in contrast to the results of Yen et al., who reported the generation of O2 - that was stable up to 200°C on labradorite, another common feldspar. The superoxide radical did form under UV irradiation at 77 K on albite that was not dehydrated but decayed rapidly at room temperature. On dehydrated albite, no superoxide signal was observed. We studied the kinetics of O2 - decomposition on hydrated albite and derived an activation energy, E a = 15.2 kJ/mol. Assuming pseudo first-order kinetics, a simple thermal model of Mars' regolith demonstrates that the surface O2 - population does not go to zero overnight; superoxide extinction at the surface is only complete when the seasonal CO2 cap covers the surface and surface photolysis is inhibited. Depending on the specific quantum efficiency of the e-/h+ generation process, a finite, non-equilibrium population of O2 - should be observable on Martian surface materials throughout the Martian year. However, on the basis of our inability to generate stable O2 - on hydrated albite via direct UV irradiation, we do not believe that this mechanism is capable of explaining the O2 release in the Viking Gas Exchange (GEx) results, since O2 release in that case was observed even after samples had been stored for 143 sols in the dark at 10°C, then heated to 145°C for 3 hours. At least two other potential pathways to the generation of O2 - are identified in this article. The first possibility is that metal oxides common on the Martian surface, particularly hematite, may be photoactive on Mars and play a role analogous to TiO2 in surface catalysis. Secondly, we found that superoxide that formed during the sorption or drying of a 1% H2O2 solution on TiO2, and potentially other oxides seems to be stable indefinitely.

  13. Mechanisms of oxidation of guanine in DNA by carbonate radical anion, a decomposition product of nitrosoperoxycarbonate.

    Science.gov (United States)

    Lee, Young Ae; Yun, Byeong Hwa; Kim, Seog K; Margolin, Yelena; Dedon, Peter C; Geacintov, Nicholas E; Shafirovich, Vladimir

    2007-01-01

    Peroxynitrite is produced during inflammation and combines rapidly with carbon dioxide to yield the unstable nitrosoperoxycarbonate, which decomposes (in part) to CO(3) (.-) and (.)NO(2) radicals. The CO(3) (.-) radicals oxidize guanine bases in DNA through a one-electron transfer reaction process that ultimately results in the formation of stable guanine oxidation products. Here we have explored these mechanisms, starting with a spectroscopic study of the kinetics of electron transfer from 20-22mer double-stranded oligonucleotides to CO(3) (.-) radicals, together with the effects of base sequence on the formation of the end-products in runs of one, two, or three contiguous guanines. The distributions of these alkali-labile lesions were determined by gel electrophoresis methods. The cascade of events was initiated through the use of 308 nm XeCl excimer laser pulses to generate CO(3) (.-) radicals by an established method based on the photodissociation of persulfate to sulfate radicals and the oxidation of bicarbonate. Although the Saito model (Saito et al., J. Am. Chem. Soc. 1995, 117, 6406-6407) predicts relative ease of one-electron oxidations in DNA, following the trend 5'-GGG > 5'-GG > 5'-G, we found that the rate constants for CO(3) (.-)-mediated oxidation of guanines in these sequence contexts (k(5)) showed only small variation within a narrow range [(1.5-3.0)x10(7) M(-1) s(-1)]. In contrast, the distributions of the end-products are dependent on the base sequence context and are higher at the 5'-G in 5'-GG sequences and at the first two 5'-guanines in the 5'-GGG sequences. These effects are attributed to a combination of initial hole distributions among the contiguous guanines and the subsequent differences in chemical reaction yields at each guanine. The lack of dependence of k(5) on sequence context indicates that the one-electron oxidation of guanine in DNA by CO(3) (.-) radicals occurs by an inner-sphere mechanism.

  14. Electron attachment to solvated dGpdG: effects of stacking on base-centered and phosphate-centered valence-bound radical anions.

    Science.gov (United States)

    Gu, Jiande; Liang, Guoming; Xie, Yaoming; Schaefer, Henry F

    2012-04-23

    To explore the nature of electron attachment to guanine-centered DNA single strands in the presence of a polarizable medium, a theoretical investigation of the DNA oligomer dinucleoside phosphate deoxyguanylyl-3',5'-deoxyguanosine (dGpdG) was performed by using density functional theory. Four different electron-distribution patterns for the radical anions of dGpdG in aqueous solution have been located as local minima on the potential energy surface. The excess electron is found to reside on the proton of the phosphate group (dGp(H-)dG), or on the phosphate group (dGp(.-)dG), or on the nucleobase at the 5' position (dG(.-)pdG), or on the nucleobase at the 3' position (dGpdG(.-)), respectively. These four radical anions are all expected to be electronically viable species under the influence of the polarizable medium. The predicted energetics of the radical anions follows the order dGp(.-)dG>dG(.-)pdG>dGpdG(.-)>dGp(H-)dG. The base-base stacking pattern in DNA single strands seems unaffected by electron attachment. On the contrary, intrastrand H-bonding is greatly influenced by electron attachment, especially in the formation of base-centered radical anions. The intrastrand H-bonding patterns revealed in this study also suggest that intrastrand proton transfer might be possible between successive guanines due to electron attachment to DNA single strands.

  15. Superoxide radical-mediated photocatalytic oxidation of phenolic compounds over Ag⁺/TiO₂: Influence of electron donating and withdrawing substituents.

    Science.gov (United States)

    Xiao, Jiadong; Xie, Yongbing; Han, Qingzhen; Cao, Hongbin; Wang, Yujiao; Nawaz, Faheem; Duan, Feng

    2016-03-05

    A comparative study was constructed to correlate the electronic property of the substituents with the degradation rates of phenolic compounds and their oxidation pathways under UV with Ag(+)/TiO2 suspensions. It was verified that a weak electron withdrawing substituent benefited photocatalytic oxidation the most, while an adverse impact appeared when a substituent was present with stronger electron donating or withdrawing ability. The addition of p-benzoquinone dramatically blocked the degradation, confirming superoxide radicals (O2(-)) as the dominant photooxidant, rather than hydroxyl radicals, singlet oxygen or positive holes, which was also independent of the substituent. Hammett relationship was established based on pseudo-first-order reaction kinetics, and it revealed two disparate reaction patterns between O2(-) and phenolic compounds, which was further verified by the quantum chemical computation on the frontier molecular orbitals and Mulliken charge distributions of O2(-) and phenolic compounds. It was found that electron donating group (EDG) substituted phenols were more likely nucleophilically attacked by O2(-), while O2(-) preferred to electrophilically assault electron withdrawing group (EWG) substituted phenols. Exceptionally, electrophilic and nucleophilic attack by O2(-) could simultaneously occur in p-chlorophenol degradation, consequently leading to its highest rate constant. Possible reactive positions on the phenolic compounds were also detailedly uncovered.

  16. Direction-Dependent Effects of Combined Static and ELF Magnetic Fields on Cell Proliferation and Superoxide Radical Production.

    Science.gov (United States)

    Naarala, Jonne; Kesari, Kavindra Kumar; McClure, Ian; Chavarriaga, Cristina; Juutilainen, Jukka; Martino, Carlos F

    2017-01-01

    Proliferation of human umbilical vein endothelial cells was stimulated by a nearly vertical 60 or 120 μT static magnetic field (MF) in comparison to cells that were shielded against MFs. When the static field was combined with an extremely low frequency (ELF) MF (18 Hz, 30 μT), proliferation was suppressed by a horizontal but not by a vertical ELF field. As these results suggested that the effects of an ELF MF depend on its direction in relation to the static MF, independent experiments were carried out to confirm such dependence using 50 Hz MFs and a different experimental model. Cytosolic superoxide level in rat glioma C6 cells exposed in the presence of a nearly vertical 33 μT static MF was increased by a horizontal 50 Hz, 30 μT MF, but not affected by a vertical 50 Hz MF. The results suggest that a weak ELF MF may interact with the static geomagnetic field in producing biological effects, but the effect depends on the relative directions of the static and ELF MFs.

  17. EPR characterization of ascorbyl and sulfur dioxide anion radicals trapped during the reaction of bovine Cytochrome c Oxidase with molecular oxygen

    Science.gov (United States)

    Yu, Michelle A.; Egawa, Tsuyoshi; Yeh, Syun-Ru; Rousseau, Denis L.; Gerfen, Gary J.

    2010-04-01

    The reaction intermediates of reduced bovine Cytochrome c Oxidase (CcO) were trapped following its reaction with oxygen at 50 μs-6 ms by innovative freeze-quenching methods and studied by EPR. When the enzyme was reduced with either ascorbate or dithionite, distinct radicals were generated; X-band (9 GHz) and D-band (130 GHz) CW-EPR measurements support the assignments of these radicals to ascorbyl and sulfur dioxide anion radical (SO2-rad), respectively. The X-band spectra show a linewidth of 12 G for the ascorbyl radical and 11 G for the SO2-rad radical and an isotropic g-value of 2.005 for both species. The D-band spectra reveal clear distinctions in the g-tensors and powder patterns of the two species. The ascorbyl radical spectrum displays approximate axial symmetry with g-values of gx = 2.0068, gy = 2.0066, and gz = 2.0023. The SO2-rad>/SUP> radical has rhombic symmetry with g-values of gx = 2.0089, gy = 2.0052, and gz = 2.0017. When the contributions from the ascorbyl and SO2-rad radicals were removed, no protein-based radical on CcO could be identified in the EPR spectra.

  18. Vibrio vulnificus MO6-24/O Lipopolysaccharide Stimulates Superoxide Anion, Thromboxane B2, Matrix Metalloproteinase-9, Cytokine and Chemokine Release by Rat Brain Microglia in Vitro

    Directory of Open Access Journals (Sweden)

    Alejandro M. S. Mayer

    2014-03-01

    Full Text Available Although human exposure to Gram-negative Vibrio vulnificus (V. vulnificus lipopolysaccharide (LPS has been reported to result in septic shock, its impact on the central nervous system’s innate immunity remains undetermined. The purpose of this study was to determine whether V. vulnificus MO6-24/O LPS might activate rat microglia in vitro and stimulate the release of superoxide anion (O2−, a reactive oxygen species known to cause oxidative stress and neuronal injury in vivo. Brain microglia were isolated from neonatal rats, and then treated with either V. vulnificus MO6-24/O LPS or Escherichia coli O26:B6 LPS for 17 hours in vitro. O2− was determined by cytochrome C reduction, and matrix metalloproteinase-2 (MMP-2 and MMP-9 by gelatinase zymography. Generation of cytokines tumor necrosis factor alpha (TNF-α, interleukin-1 alpha (IL-1α, IL-6, and transforming growth factor-beta 1 (TGF-β1, chemokines macrophage inflammatory protein (MIP-1α/chemokine (C-C motif ligand 3 (CCL3, MIP-2/chemokine (C-X-C motif ligand 2 (CXCL2, monocyte chemotactic protein-1 (MCP-1/CCL2, and cytokine-induced neutrophil chemoattractant-2alpha/beta (CINC-2α/β/CXCL3, and brain-derived neurotrophic factor (BDNF, were determined by specific immunoassays. Priming of rat microglia by V. vulnificus MO6-24/O LPS in vitro yielded a bell-shaped dose-response curve for PMA (phorbol 12-myristate 13-acetate-stimulated O2− generation: (1 0.1–1 ng/mL V. vulnificus LPS enhanced O2− generation significantly but with limited inflammatory mediator generation; (2 10–100 ng/mL V. vulnificus LPS maximized O2− generation with concomitant release of thromboxane B2 (TXB2, matrix metalloproteinase-9 (MMP-9, and several cytokines and chemokines; (3 1000–100,000 ng/mL V. vulnificus LPS, with the exception of TXB2, yielded both attenuated O2− production, and a progressive decrease in MMP-9, cytokines and chemokines investigated. Thus concentration-dependent treatment of

  19. Vibrio vulnificus MO6-24/O lipopolysaccharide stimulates superoxide anion, thromboxane B₂, matrix metalloproteinase-9, cytokine and chemokine release by rat brain microglia in vitro.

    Science.gov (United States)

    Mayer, Alejandro M S; Hall, Mary L; Holland, Michael; De Castro, Cristina; Molinaro, Antonio; Aldulescu, Monica; Frenkel, Jeffrey; Ottenhoff, Lauren; Rowley, David; Powell, Jan

    2014-03-26

    Although human exposure to Gram-negative Vibrio vulnificus (V. vulnificus) lipopolysaccharide (LPS) has been reported to result in septic shock, its impact on the central nervous system's innate immunity remains undetermined. The purpose of this study was to determine whether V. vulnificus MO6-24/O LPS might activate rat microglia in vitro and stimulate the release of superoxide anion (O₂⁻), a reactive oxygen species known to cause oxidative stress and neuronal injury in vivo. Brain microglia were isolated from neonatal rats, and then treated with either V. vulnificus MO6-24/O LPS or Escherichia coli O26:B6 LPS for 17 hours in vitro. O₂⁻ was determined by cytochrome C reduction, and matrix metalloproteinase-2 (MMP-2) and MMP-9 by gelatinase zymography. Generation of cytokines tumor necrosis factor alpha (TNF-α), interleukin-1 alpha (IL-1α), IL-6, and transforming growth factor-beta 1 (TGF-β1), chemokines macrophage inflammatory protein (MIP-1α)/chemokine (C-C motif) ligand 3 (CCL3), MIP-2/chemokine (C-X-C motif) ligand 2 (CXCL2), monocyte chemotactic protein-1 (MCP-1)/CCL2, and cytokine-induced neutrophil chemoattractant-2alpha/beta (CINC-2α/β)/CXCL3, and brain-derived neurotrophic factor (BDNF), were determined by specific immunoassays. Priming of rat microglia by V. vulnificus MO6-24/O LPS in vitro yielded a bell-shaped dose-response curve for PMA (phorbol 12-myristate 13-acetate)-stimulated O₂⁻ generation: (1) 0.1-1 ng/mL V. vulnificus LPS enhanced O₂⁻ generation significantly but with limited inflammatory mediator generation; (2) 10-100 ng/mL V. vulnificus LPS maximized O₂⁻ generation with concomitant release of thromboxane B2 (TXB2), matrix metalloproteinase-9 (MMP-9), and several cytokines and chemokines; (3) 1000-100,000 ng/mL V. vulnificus LPS, with the exception of TXB2, yielded both attenuated O₂⁻ production, and a progressive decrease in MMP-9, cytokines and chemokines investigated. Thus concentration-dependent treatment of

  20. [Involvement of carbonate/bicarbonate ions in the superoxide-generating reaction of adrenaline autoxidation].

    Science.gov (United States)

    Sirota, T V

    2015-01-01

    An important role of carbonate/bicarbonate ions has been recognized in the superoxide generating reaction of adrenaline autooxidation in an alkaline buffer (a model of quinoid adrenaline oxidation in the body). It is suggested that these ions are directly involved not only in formation of superoxide anion radical (О(2)(-)) but also other radicals derived from the carbonate/bicarbonate buffer. Using various buffers it was shown that the rate of accumulation of adrenochrome, the end product of adrenaline oxidation, and the rate of О(2)(-)· formation depend on concentration of carbonate/bicarbonate ions in the buffer and that these ions significantly accelerate adrenaline autooxidation thus demonstrating prooxidant properties. The detectable amount of diformazan, the product of nitro blue tetrazolium (NBT) reduction, was significantly higher than the amount of adrenochrome formed; taking into consideration the literature data on О(2)(-)· detection by NBT it is suggested that adrenaline autooxidation is accompanied by one-electron reduction not only of oxygen dissolved in the buffer and responsible for superoxide formation but possible carbon dioxide also dissolved in the buffer as well as carbonate/bicarbonate buffer components leading to formation of corresponding radicals. The plots of the dependence of the inhibition of adrenochrome and diformazan formation on the superoxide dismutase concentration have shown that not only superoxide radicals are formed during adrenaline autooxidation. Since carbonate/bicarbonate ions are known to be universally present in the living nature, their involvement in free radical processes proceeding in the organism is discussed.

  1. EPR studies of the vitamin K 1 semiquinone radical anion. Comparison to the electron acceptor A 1 in green plant photosystem I

    Science.gov (United States)

    Thurnauer, Marion C.; Brown, James W.; Gast, P.; Feezel, Laura L.

    Suggestions that the electron acceptor, A 1, in Photosystem I is a quinone have come from both optical and epr experiments. Vitamin K 1 (phylloquinone) is present in the PSI complex with a stoichiometry of two molecules per reaction center. In order to determine if A 1 can be identified with vitamin K 1, X-band and Q-band epr properties of the vitamin K 1 radical anion in frozen alcohol solutions are examined. The results are compared to the epr properties that have been observed for the reduced A 1 acceptor in vivo. The g-values obtained for the vitamin K 1 radical anion are consistent with identifying A 1 with vitamin K 1.

  2. Oxygen Activation by Co(II) and a Redox Non-Innocent Ligand: Spectroscopic Characterization of a Radical-Co(II)-Superoxide Complex with Divergent Catalytic Reactivity.

    Science.gov (United States)

    Corcos, Amanda R; Villanueva, Omar; Walroth, Richard C; Sharma, Savita K; Bacsa, John; Lancaster, Kyle M; MacBeth, Cora E; Berry, John F

    2016-02-17

    Bimetallic (Et4N)2[Co2(L)2], (Et4N)2[1] (where (L)(3-) = (N(o-PhNC(O)(i)Pr)2)(3-)) reacts with 2 equiv of O2 to form the monometallic species (Et4N)[Co(L)O2], (Et4N)[3]. A crystallographically characterized analog (Et4N)2[Co(L)CN], (Et4N)2[2], gives insight into the structure of [3](1-). Magnetic measurements indicate [2](2-) to be an unusual high-spin Co(II)-cyano species (S = 3/2), while IR, EXAFS, and EPR spectroscopies indicate [3](1-) to be an end-on superoxide complex with an S = 1/2 ground state. By X-ray spectroscopy and calculations, [3](1-) features a high-spin Co(II) center; the net S = 1/2 spin state arises after the Co electrons couple to both the O2(•-) and the aminyl radical on redox non-innocent (L(•))(2-). Dianion [1](2-) shows both nucleophilic and electrophilic catalytic reactivity upon activation of O2 due to the presence of both a high-energy, filled O2(-) π* orbital and an empty low-lying O2(-) π* orbital in [3](1-).

  3. 1,4-Anhydro-4-seleno-d-talitol (SeTal) protects endothelial function in the mouse aorta by scavenging superoxide radicals under conditions of acute oxidative stress

    DEFF Research Database (Denmark)

    Ng, Hooi Hooi; Leo, Chen Huei; O'Sullivan, Kelly

    2016-01-01

    . Aortae were isolated from C57BL/6 male mice and mounted on a wire-myograph to assess vascular function. In the presence of a superoxide radical generator, pyrogallol, 300μM and 1mM of SeTal effectively prevented endothelial dysfunction compared to other selenium-containing compounds. In a second set...... of ex vivo experiments, mouse aortae were incubated for three days with either normal or high glucose, and co-incubated with SeTal at 37°C in 5% CO2. High glucose significantly reduced the sensitivity to the endothelium-dependent agonist, acetylcholine (ACh), increased superoxide production......, but had no effect in SeTal-treated aortae. Our data show that SeTal has potent antioxidant activity in isolated mouse aortae and prevents high glucose-induced endothelial dysfunction by decreasing superoxide levels, increasing basal NO availability and normalising the contribution of vasoconstrictor...

  4. Homoleptic 2,2'-bipyridine metalates(-I) of iron and cobalt, one cocrystallized with an anthracene radical anion and the other with neutral anthracene.

    Science.gov (United States)

    Brennessel, William W; Ellis, John E

    2014-08-01

    Homoleptic 2,2'-bipyridine (bipy) metalates of iron and cobalt have been synthesized directly from the corresponding homoleptic anthracene metalates. In the iron structure, bis[([2.2.2]cryptand)potassium(I)] tris(2,2'-bipyridine)ferrate(-I) anthracene(-I), [K(C18H36N2O6)]2[Fe(C10H8N2)3](C14H10), the asymmetric unit contains one potassium complex cation in a general position, the Fe center and one and a half bipy ligands of the ferrate complex on a crystallographic twofold axis that includes the Fe atom, and one half of an anthracene radical anion whose other half is generated by a crystallographic inversion center. The cations and anions are well separated and the geometry about the Fe center is essentially octahedral. In the cobalt structure, ([2.2.2]cryptand)potassium(I) bis(2,2'-bipyridine)cobaltate(-I) anthracene hemisolvate tetrahydrofuran (THF) disolvate, [K(C18H36N2O6)][Co(C10H8N2)2]·0.5C14H10·2C4H8O, the asymmetric unit contains the cation, anion, and both cocrystallized THF solvent molecules in general positions, and one half of a cocrystallized anthracene molecule whose other half is generated by a crystallographic inversion center. The cation and anion are well separated and the ligand planes in the cobaltate anion are periplanar. Each anthracene molecule is midway between and is oriented perpendicular to a pair of symmetry-related bipy ligands such that aromatic donor-acceptor interactions may play a role in the packing arrangement. The lengths of the bonds that connect the bipy rings support the assertion that the ligands are bipy radical anions in the iron structure. However, in the case of cobalt, these lengths are between the known ranges for a bipy radical anion and a bipy dianion, and therefore no conclusion can be made from the crystallography alone. One cocrystallized THF solvent molecule in the cobalt structure was modeled as disordered over three positions with appropriate geometric and thermal restraints, which resulted in a refined

  5. Oxygen radical production in leukocytes and disease severity in multiple sclerosis.

    Science.gov (United States)

    Mossberg, Natalia; Movitz, Charlotta; Hellstrand, Kristoffer; Bergström, Tomas; Nilsson, Staffan; Andersen, Oluf

    2009-08-18

    This study investigated the relationship between the formation of NADPH oxidase-dependent oxygen radicals in peripheral blood leukocytes ('respiratory burst') and disease severity in patients with multiple sclerosis (MS). Oxygen radical production was induced by formyl-Met-Leu-Phe (fMLF), Trp-Lys-Tyr-Met-Val-Met-NH2 (WKYMVM) or phorbol myristate acetate (PMA) and was assessed by quantifying superoxide anion, i.e. the initial radical formed by the NADPH oxidase. Disease severity was evaluated using the Multiple Sclerosis Severity Score (MSSS). In patients with severe disease, the production of superoxide anion was significantly lower for all three inducers of radical formation (p=0.04-0.004). Our findings are supportive of a protective role of oxygen radicals in autoimmunity.

  6. Ag/g-C3N4 catalyst with superior catalytic performance for the degradation of dyes: a borohydride-generated superoxide radical approach

    Science.gov (United States)

    Fu, Yongsheng; Huang, Ting; Zhang, Lili; Zhu, Junwu; Wang, Xin

    2015-08-01

    A straightforward approach is developed for fabrication of a visible-light-driven Ag/g-C3N4 catalyst. Morphological observation shows that the g-C3N4 sheets are decorated with highly dispersed Ag nanoparticles having an average size of 5.6 nm. The photocatalytic activity measurements demonstrate that the photocatalytic degradation rates of methyl orange (MO), methylene blue (MB), and neutral dark yellow GL (NDY-GL) over Ag/g-C3N4-4 can reach up to 98.2, 99.3 and 99.6% in the presence of borohydride ions (BH4-) only with 8, 45, and 16 min visible light irradiation, respectively. The significant enhancement in photoactivity of the catalyst is mainly attributed to the high dispersity and smaller size of Ag nanoparticles, the strong surface plasmon resonance (SPR) effect of metallic Ag nanoparticles, the efficient separation of photogenerated charge carriers, the additional superoxide radicals (O&z.rad;-2) generated from the reduction of dissolved oxygen in the presence of BH4- and the synergistic effect of Ag nanoparticles and g-C3N4.A straightforward approach is developed for fabrication of a visible-light-driven Ag/g-C3N4 catalyst. Morphological observation shows that the g-C3N4 sheets are decorated with highly dispersed Ag nanoparticles having an average size of 5.6 nm. The photocatalytic activity measurements demonstrate that the photocatalytic degradation rates of methyl orange (MO), methylene blue (MB), and neutral dark yellow GL (NDY-GL) over Ag/g-C3N4-4 can reach up to 98.2, 99.3 and 99.6% in the presence of borohydride ions (BH4-) only with 8, 45, and 16 min visible light irradiation, respectively. The significant enhancement in photoactivity of the catalyst is mainly attributed to the high dispersity and smaller size of Ag nanoparticles, the strong surface plasmon resonance (SPR) effect of metallic Ag nanoparticles, the efficient separation of photogenerated charge carriers, the additional superoxide radicals (O&z.rad;-2) generated from the reduction of

  7. Metabolic stability of superoxide and hydroxyl radical adducts of a cyclic nitrone toward rat liver microsomes and cytosol: A stopped-flow ESR spectroscopy study.

    Science.gov (United States)

    Bézière, Nicolas; Frapart, Yves; Rockenbauer, Antal; Boucher, Jean-Luc; Mansuy, Daniel; Peyrot, Fabienne

    2010-08-01

    The metabolic stability of the spin adducts derived from the reaction of superoxide and hydroxyl radicals with 5-tert-butoxycarbonyl-5-methyl-1-pyrroline N-oxide (BocMPO) in the presence of rat liver microsomes (RLM) and rat liver cytosol (RLC) was studied by using a stopped-flow device coupled to an electron spin resonance (ESR) spectrometer. The kinetics of the disappearance of the BocMPO-OH and BocMPO-OOH radicals could be followed by ESR spectroscopy with treatment of the ESR data by an appropriate computer program. The presence of cytosol led to a 60-fold decrease of the half-life of BocMPO-OOH with the intermediate formation of BocMPO-OH. This effect of cytosol was due to an ascorbate- and thiol-dependent reduction of BocMPO-OOH. RLC only led to a 5-fold decrease of the half-life of BocMPO-OH that was predominantly due to cytosolic ascorbate. RLM led to a 10-fold decrease of the BocMPO-OOH half-life that was mainly related to a direct reaction of the hydroperoxide function of BocMPO-OOH with cytochrome P450 Fe(III) (P450). Other ferric heme proteins, such as methemoglobin (metHb) and horseradish peroxidase (HRP), as well as hemin itself, exhibited a similar behavior. RLM and metHb showed a much weaker effect on BocMPO-OH half-life (2-fold decrease), whereas RLM in the presence of NADPH caused a greater decrease of the BocMPO-OH half-life ( approximately 5-fold). The effect of RLM without NADPH was mainly due to a direct reaction with microsomal P450, whereas the RLM- and NADPH-dependent effect was mainly due to flavin-containing reductases such as cytochrome P450 reductase. These data on the effects of liver subcellular fractions on the half-life of the BocMPO-OOH and the BocMPO-OH spin adducts highlight the role of heme as a biological cofactor involved in the disappearance of such spin adducts. They should be helpful for the design of new spin traps that would form more metabolically stable spin adducts in vitro and in vivo.

  8. Hydroxyl radical generation by red tide algae.

    Science.gov (United States)

    Oda, T; Akaike, T; Sato, K; Ishimatsu, A; Takeshita, S; Muramatsu, T; Maeda, H

    1992-04-01

    The unicellular marine phytoplankton Chattonella marina is known to have toxic effects against various living marine organisms, especially fishes. However, details of the mechanism of the toxicity of this plankton remain obscure. Here we demonstrate the generation of superoxide and hydroxyl radicals from a red tide unicellular organism, C. marina, by using ESR spectroscopy with the spin traps 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and N-t-butyl-alpha-phenylnitrone (PBN), and by using the luminol-enhanced chemiluminescence response. The spin-trapping assay revealed productions of spin adduct of superoxide anion (O2-) (DMPO-OOH) and that of hydroxyl radical (.OH) (DMPO-OH) in the algal suspension, which was not observed in the ultrasonic-ruptured suspension. The addition of superoxide dismutase (500 U/ml) almost completely inhibited the formation of both DMPO-OOH and DMPO-OH, and carbon-centered radicals were generated with the disappearance of DMPO-OH after addition of 5% dimethyl sulfoxide (Me2SO) and 5% ethanol. Furthermore, the generation of methyl and methoxyl radicals, which are thought to be produced by the reaction of hydroxyl radical and Me2SO under aerobic condition, was identified using spin trapping with a combination of PBN and Me2SO. Luminol-enhanced chemiluminescence assay also supported the above observations. These results clearly indicate that C. marina generates and releases the superoxide radical followed by the production of hydroxyl radical to the surrounding environment. The velocity of superoxide generation by C. marina was about 100 times faster than that by mammalian phagocytes per cell basis. The generation of oxygen radical is suggested to be a pathogenic principle in the toxication of red tide to susceptible aquaculture fishes and may be directly correlated with the coastal pollution by red tide.

  9. The cytoplasmic Cu,Zn superoxide dismutase of saccharomyces cerevisiae is required for resistance to freeze-thaw stress. Generation of free radicals during freezing and thawing

    DEFF Research Database (Denmark)

    Park, J I; Grant, C M; Davies, Michael Jonathan

    1998-01-01

    The involvement of oxidative stress in freeze-thaw injury to yeast cells was analyzed using mutants defective in a range of antioxidant functions, including Cu,Zn superoxide dismutase (encoded by SOD1), Mn superoxide dismutase (SOD2), catalase A, catalase T, glutathione reductase, gamma-glutamylc...

  10. Calculation of the properties of the S3- radical anion and its complexes with Cu+ in aqueous solution

    Science.gov (United States)

    Tossell, J. A.

    2012-10-01

    A species observed in aqueous sulfidic solutions at high T and P has recently been identified as the anion radical S3-, based on the Raman spectrum obtained in a hydrothermal diamond-anvil cell (Pokrovski and Dubrovinsky, 2011, Science, 331, 1052-1054). Such a species had not been expected to occur in such environments, although S3- as an component of lapis lazuli, other solids and even albite melt has been well studied (Winther et al., 1998; Reinen and Lindner, 1999; Arieli et al., 2004; Shnitko et al., 2008; Bacci et al., 2009). We have calculated the structures, energetics, vibrational and UV-visible spectra of S3- and several other similar species and confirm the species identification of Pokrovski and Dubrovinsky, although we are still somewhat concerned about the apparent lack of a third peak which we calculate to be present in the Raman spectrum of S3-. Our calculations indicate that the reaction: S6-2⇒2S3- in aqueous solution has a free energy change of +3 kcal/mol at 298 K and 1 atm pressure but -13 kcal/mol at 723 K and 1 atm pressure, consistent with the disappearance of disulfide species and the appearance of S3-at high T. Likewise, the free energy for the reaction: 2HS+SO4-2+H⇒S3-+.75O+2.5HO decreases from 44.1 to 19.0 kcal/mol between 298 and 723 K (again at 1 atm). This is consistent with the decrease in concentrations of SH- and SO4-2 and the formation of S3- observed by Pokrovski and Dubrovinski over this temperature range. The corresponding log K values are in semiquantitative agreement with those found by Pokrovski and Dubrovinsky. The main contribution to these changes in reaction free energy with temperature come from the VRT (vibrational-rotational-translational) contribution to the gas-phase free energy, while the hydration free energy difference changes little. Calculation of 34S-32S isotopic fractionations for S3- at 298 K give δ values of around +4.3% relative to H2S, a value intermediate between that of S3 and S3-2. Calculated free

  11. Fluorinated Dodecaphenylporphyrins: Synthetic and Electrochemical Studies Including the First Evidence of Intramolecular Electron Transfer Between an Fe(II) Porphyrin -Anion Radical and an Fe(I) Porphyrin

    Energy Technology Data Exchange (ETDEWEB)

    D' Souza, F.; Forsyth, T.P.; Fukuzumi, S.; Kadish, K.M.; Krattinger, B.; Lin, M.; Medforth, C.J.; Nakanishi, I.; Nurco, D.J.; Shelnutt, J.A.; Smith, K.M.; Van Caemelbecke, E.

    1998-10-19

    Dodecaphenylporphyrins with varying degrees of fluorination of the peripheral phenyl rings (FXDPPS) were synthesized as model compounds for studying electronic effects in nonplan~ porphyrins, and detailed electrochemical studies of the chloroiron(HI) complexes of these compounds were undertaken. The series of porphyrins, represented as FeDPPCl and as FeFXDPPCl where x = 4, 8 (two isomers), 12, 20,28 or 36, could be reversibly oxidized by two electrons in dichloromethane to give n-cation radicals and n-dications. All of the compounds investigated could also be reduced by three electrons in benzonitrile or pyridine. In benzonitrile, three reversible reductions were observed for the unfluorinated compound FeDPPC1, whereas the FeFXDPPCl complexes generally exhibited irreversible first and second reductions which were coupled to chemical reactions. The chemical reaction associated with the first reduction involved a loss of the chloride ion after generation of Fe FXDPPC1. The second chemical reaction involved a novel intramolecular electron transfer between the initially generated Fe(H) porphyrin n-anion radical and the final Fe(I) porphyrin reduction product. In pyridine, three reversible one electron reductions were observed with the second reduction affording stable Fe(II) porphyrin o - anion radicals for ail of the complexes investigated.

  12. Preparation of high-capacity, weak anion-exchange membranes by surface-initiated atom transfer radical polymerization of poly(glycidyl methacrylate) and subsequent derivatization with diethylamine

    Science.gov (United States)

    Qian, Xiaolei; Fan, Hua; Wang, Chaozhan; Wei, Yinmao

    2013-04-01

    Ion-exchange membrane is of importance for the development of membrane chromatography. In this work, a high-capacity anion-exchange membrane was prepared by grafting of glycidyl methacrylate (GMA) onto the surface of regenerated cellulose (RC) membranes via surface-initiated atom transfer radical polymerization (SI-ATRP) and subsequent derivatization with diethylamine. Attenuated total reflectance Fourier-transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to characterize changes in the chemical functionality, surface topography and pore morphology of the modified membranes. The static capacity of the prepared anion-exchange membrane was evaluated with bovine serum albumin (BSA) as a model protein. The results indicated that the anion-exchange membrane which could reach a maximum capacity of 96 mg/mL for static adsorption possesses a higher adsorption capacity, and the adsorption capacity increases with the polymerization time. The effect of pH and salt concentration confirmed that the adsorption of BSA followed ion-exchange mechanism. The established method would have potential application in the preparation of anion-exchange membrane.

  13. Gas-phase reactions of molecular oxygen with uranyl(V) anionic complexes-synthesis and characterization of new superoxides of uranyl(VI).

    Science.gov (United States)

    Lucena, Ana F; Carretas, José M; Marçalo, Joaquim; Michelini, Maria C; Gong, Yu; Gibson, John K

    2015-04-16

    Gas-phase complexes of uranyl(V) ligated to anions X(-) (X = F, Cl, Br, I, OH, NO3, ClO4, HCO2, CH3CO2, CF3CO2, CH3COS, NCS, N3), [UO2X2](-), were produced by electrospray ionization and reacted with O2 in a quadrupole ion trap mass spectrometer to form uranyl(VI) anionic complexes, [UO2X2(O2)](-), comprising a superoxo ligand. The comparative rates for the oxidation reactions were measured, ranging from relatively fast [UO2(OH)2](-) to slow [UO2I2](-). The reaction rates of [UO2X2](-) ions containing polyatomic ligands were significantly faster than those containing the monatomic halogens, which can be attributed to the greater number of vibrational degrees of freedom in the polyatomic ligands to dissipate the energy of the initial O2-association complexes. The effect of the basicity of the X(-) ligands was also apparent in the relative rates for O2 addition, with a general correlation between increasing ligand basicity and O2-addition efficiency for polyatomic ligands. Collision-induced dissociation of the superoxo complexes showed in all cases loss of O2 to form the [UO2X2](-) anions, indicating weaker binding of the O2(-) ligand compared to the X(-) ligands. Density functional theory computations of the structures and energetics of selected species are in accord with the experimental observations.

  14. Evidence for the interaction between (t)BuOK and 1,10-phenanthroline to form the 1,10-phenanthroline radical anion: a key step for the activation of aryl bromides by electron transfer.

    Science.gov (United States)

    Yi, Hong; Jutand, Anny; Lei, Aiwen

    2015-01-11

    Electron paramagnetic resonance and electrochemistry are used to evidence the interaction between 1,10-phenanthroline (Phen) and KO(t)Bu to form the 1,10-phenanthroline radical anion, Phen˙(-), and the (t)BuO˙ radical via an inner-sphere electron transfer. In addition, electrochemistry is also used to explain the formation of aryl radicals from aryl bromides via outer-sphere electron transfer from the key intermediate Phen˙(-).

  15. Cadmium Disrupts the Balance between Hydrogen Peroxide and Superoxide Radical by Regulating Endogenous Hydrogen Sulfide in the Root Tip of Brassica rapa

    Science.gov (United States)

    Lv, Wenjing; Yang, Lifei; Xu, Cunfa; Shi, Zhiqi; Shao, Jinsong; Xian, Ming; Chen, Jian

    2017-01-01

    Cd (cadmium) stress always alters the homeostasis of ROS (reactive oxygen species) including H2O2 (hydrogen sulfide) and O2•– (superoxide radical), leading to the oxidative injury and growth inhibition in plants. In addition to triggering oxidative injury, ROS has been suggested as important regulators modulating root elongation. However, whether and how Cd stress induces the inhibition of root elongation by differentially regulating endogenous H2O2 and O2•–, rather than by inducing oxidative injury, remains elusive. To address these gaps, histochemical, physiological, and biochemical approaches were applied to investigate the mechanism for Cd to fine-tune the balance between H2O2 and O2•– in the root tip of Brassica rapa. Treatment with Cd at 4 and 16 μM significantly inhibited root elongation, while only 16 μM but not 4 μM of Cd induced oxidative injury and cell death in root tip. Fluorescent and pharmaceutical tests suggested that H2O2 and O2•– played negative and positive roles, respectively, in the regulation of root elongation in the presence of Cd (4 μM) or not. Treatment with Cd at 4 μM led to the increase in H2O2 and the decrease in O2•– in root tip, which may be attributed to the up-regulation of Br_UPB1s and the down-regulation of their predicted targets (four peroxidase genes). Cd at 4 μM resulted in the increase in endogenous H2S in root tip by inducing the up-regulation of LCDs and DCDs. Treatment with H2S biosynthesis inhibitor or H2S scavenger significantly blocked Cd (4 μM)-induced increase in endogenous H2S level, coinciding with the recovery of root elongation, the altered balance between H2O2 and O2•–, and the expression of Br_UPB1s and two peroxidase genes. Taken together, it can be proposed that endogenous H2S mediated the phytotoxicity of Cd at low concentration by regulating Br_UPB1s-modulated balance between H2O2 and O2•– in root tip. Such findings shed new light on the regulatory role of endogenous H2S in

  16. Apple pectin-derived oligosaccharides produce carbon dioxide radical anion in Fenton reaction and prevent growth of Escherichia coli and Staphylococcus aureus.

    Science.gov (United States)

    Martinov, Jelena; Krstić, Miodrag; Spasić, Snežana; Miletić, Srdjan; Stefanović-Kojić, Jovana; Nikolić-Kokić, Aleksandra; Blagojević, Duško; Spasojević, Ivan; Spasić, Mihajlo B

    2017-10-01

    Pectin is the main soluble fiber in apples or citruses. It may be fermented by gut microbiota to metabolites showing local intestinal and systemic effects. A wide range of beneficial effects of dietary pectin includes impacts on the redox milieu and microbiota profile. We prepared pectin-derived oligosaccharides (apple (APDO) and citrus) and polygalacturonic acid-derived oligosaccharides, using alkaline hydrolysis by hydrogen peroxide, and analyzed them by Fourier Transform Infrared spectrometry. Furthermore, we analyzed the effects of pectin-derived oligosaccharides on hydroxyl radical (HO)-generating Fenton reaction using electron paramagnetic resonance spin-trapping spectroscopy, and the effects on the growth of Escherichia coli and Staphylococcus aureus in the presence of dietary-relevant HO-generating system (iron+ascorbate). The oligosaccharides react with HO radical to produce carbon dioxide radical anion (CO2(-)). A comparative analysis showed that APDO has the most prominent bacteriostatic effect. This might be at least partially related to the higher capacity of APDO to produce CO2(-), which specifically targets proteins and appears to have a longer lifetime and larger diffusion radius in biological systems compared to HO. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Synthesis of calcium superoxide

    Science.gov (United States)

    Rewick, R. T.; Blucher, W. G.; Estacio, P. L.

    1972-01-01

    Efforts to prepare Ca(O2) sub 2 from reactions of calcium compounds with 100% O3 and with O(D-1) atoms generated by photolysis of O3 at 2537 A are described. Samples of Ca(OH) sub 2, CaO, CaO2, Ca metal, and mixtures containing suspected impurities to promote reaction have been treated with excess O3 under static and flow conditions in the presence and absence of UV irradiation. Studies with KO2 suggest that the superoxide anion is stable to radiation at 2537 A but reacts with oxygen atoms generated by the photolysis of O3 to form KO3. Calcium superoxide is expected to behave in an analogous.

  18. Reaction of sulphate radical anion (SO{sub 4}{sup {center_dot}}{sup -}) with cyanuric acid. A potential reaction for its degradation?

    Energy Technology Data Exchange (ETDEWEB)

    Manoj, P.; Varghese, R.; Manoj, V.M.; Aravindakumar, C.T. [Mahatma Gandhi University, School of Chemical Sciences, Kottayam (India)

    2002-01-01

    A novel reaction between sulfate radical anion (SO{sub 4}{sup {center_dot}}{sup -}) and cyanuric acid (CA), a non-degradable end product of the oxidative degradation of the triazine based herbicide, atrazine, is presented using laser flash photolysis and steady state radiolysis techniques at pH 5. A second order rate constant of 1.9x10{sup 7} dm{sup 3} mol{sup -1} s{sup -1} has been determined and the transient intermediate ({lambda}{sub max}=330 nm) is assigned to a radical cation of CA (CA{sup {center_dot}}{sup +}). The degradation profile indicated that about 76% of CA have been decomposed after an absorbed {gamma}-radiation dose of 18 kGy. It is therefore proposed that the reaction of SO{sub 4}{sup {center_dot}}{sup -} could be utilised for the degradation of CA in aqueous medium which is normally stable to any Advanced Oxidation Processes. (author)

  19. 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 μg/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.

  20. Free radical scavenging abilities of polypeptide from Chlamys farreri

    Institute of Scientific and Technical Information of China (English)

    HAN Zhiwu; CHU Xiao; LIU Chengjuan; WANG Yuejun; SUN Mi; WANG Chunbo

    2006-01-01

    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 μg/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.

  1. Inhibition of formyl peptide-stimulated superoxide anion generation by Fal-002-2 occurs mainly through the blockade of the p21-activated kinase and protein kinase C signaling pathways in ratneutrophils.

    Science.gov (United States)

    Tsai, Ya-Ru; Huang, Li-Jiau; Lin, Hui-Yi; Hung, Yun-Jie; Lee, Miau-Rong; Kuo, Sheng-Chu; Hsu, Mei-Feng; Wang, Jih-Pyang

    2013-02-15

    In formyl-Met-Leu-Phe (fMLP)-stimulated rat neutrophils, a synthetic compound, 6-chloro-2-(2-chlorophenyl)-4-oxo-1,4-dihydroquinoline-3-carboxylate (Fal-002-2), inhibited superoxide anion (O2(•-)) generation with an IC50 value of about 11μM, which was not mediated by scavenging the generated O2(•-) or by a cytotoxic effect on neutrophils. Fal-002-2 effectively attenuated the phosphorylation of Ser residues in p47(phox) and the association between p47(phox) and p22(phox) in fMLP-stimulated neutrophils. The interaction of p47(phox) with protein kinase C (PKC) isoforms (α, βI, βII, δ and ζ) was attenuated by Fal-002-2 with a similar IC50 value to that required for inhibition of O2(•-) generation, whereas Fal-002-2 had no prominent effect on PKC isoform membrane translocation and did not affect the kinase activity. Moreover, Fal-002-2 had no effect on the phosphorylation of Akt and downstream glycogen synthase kinase-3β, only slightly affected the intracellular free Ca(2+) concentration, phosphorylation of extracellular signal-regulated kinase and p38 mitogen-activated protein kinase (MAPK), but effectively attenuated the downstream MAPK-activated protein kinase-2 phosphorylation. The interaction of p21-activated kinase (PAK) 1with p47(phox), phosphorylation of PAK1 (Thr423/Ser144) and the membrane recruitment of PAK1 were effectively inhibited by Fal-002-2. Fal-002-2 also blocked the activation of Rac1 and Cdc42 in a concentration range that effectively inhibited PAK activation. Taken together, these results suggest that Fal-002-2 inhibits fMLP-stimulated O2(•-) generation in neutrophils mainly through the blockade of PKC and PAK signaling pathways and partly through p38 MAPK signaling.

  2. Peritoneal lavage cells of Indonesian thin-tail sheep mediate antibody-dependent superoxide radical cytotoxicity in vitro against newly excysted juvenile Fasciola gigantica but not juvenile Fasciola hepatica.

    Science.gov (United States)

    Piedrafita, David; Estuningsih, Endah; Pleasance, Jill; Prowse, Rhoda; Raadsma, Herman W; Meeusen, Els N T; Spithill, Terry W

    2007-04-01

    Indonesian thin-tail (ITT) sheep resist infection by Fasciola gigantica by an immunological mechanism within 2 to 4 weeks of infection yet are susceptible to F. hepatica infection. Studies of ITT sheep show that little liver damage occurs following F. gigantica infection, suggesting that the invading parasites are killed within the peritoneum or shortly after reaching the liver. We investigated whether cells isolated from the peritoneums of ITT sheep could kill newly excysted juvenile F. gigantica in vitro and act as a potential mechanism of resistance against F. gigantica infection. Peritoneal cells from F. gigantica-infected sheep, rich in macrophages and eosinophils, mediated antibody-dependent cytotoxicity against juvenile F. gigantica in vitro. Cytotoxicity was dependent on contact between the parasite and effector cells. Isolated mammary gland eosinophils of F. gigantica-infected sheep, or resident peritoneal monocytes/macrophages from uninfected sheep, also killed the juvenile parasites in vitro. By using inhibitors, we show that the molecular mechanism of killing in these assays was dependent on the production of superoxide radicals by macrophages and eosinophils. In contrast, this cytotoxic mechanism was ineffective against juvenile F. hepatica parasites in vitro. Analysis of superoxide dismutase activity and mRNA levels showed that activity and gene expression were higher in F. hepatica than in F. gigantica, suggesting a possible role for this enzyme in the resistance of F. hepatica to superoxide-mediated killing. We suggest that ovine macrophages and eosinophils, acting in concert with a specific antibody, may be important effector cells involved in the resistance of ITT sheep to F. gigantica.

  3. Pulse radiolysis studies of electron migration in DNA from DNA base-radical anions to nitroacridine intercalators in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, R.F.; Patel, K.B. (Mount Vernon Hospital, Northwood (United Kingdom). Gray Lab.); Wilson, W.R. (Univ. of Auckland School of Medicine (New Zealand))

    1991-12-07

    The reactions of the aquated electron (e{sub aq}{sup -}) with intercalators of high reduction potential (nitracrine and related basic nitroacridines) has been investigated by pulse radiolysis in the presence of DNA in aqueous solution. Under conditions where the majority of the e{sub aq}{sup -} species react initially with DNA bases (high DNA:drug ratios) a slower subsequent electron transfer to the intercalator was observed. The rate of this intra-complex transfer, expressed as DNA base pairs traversed per second, was in the range (1.2-3.1) x 10{sup 5} base pairs s{sup -1} and increased in order of the one-electron reduction potentials of the DNA-bound intercalators. No transfer was seen to the much less electron affinic des-nitro analogue of the nitroacridines. Only a small proportion of the initial DNA base radicals ({<=}50%) underwent this intra-complex electron transfer. Even for the most efficient electron trap, nitracrine, the apparent mean electron migration distance was only three base pairs. A slow secondary reduction of nitroacridines ((0.08-5.0) x 10{sup 4} base pairs s{sup -1}) was also observed with a proportion of the essentially immobile {sup .}OH-induced DNA radicals. This secondary reaction may well serve as a measure of the mobility of the DNa-bound intercalators. This study therefore implies a lack of extensive migration of DNA-associated electrons in aqueous solution, although it does not exclude the possibility that more mobile electrons produced by direct ionization of DNA might migrate over large distances. (author).

  4. In vitro screening of Crataegus succulenta extracts for free radical scavenging and 15-lipoxygenase inhibitory activities.

    Science.gov (United States)

    Bedreag, Catrinel Florentina Giurescu; Trifan, Adriana; Vasincu, Al; Miron, S D; Aprotosoaie, Ana Clara; Miron, Anca

    2014-01-01

    Crataegus succulenta Schrad. ex Link is widely spread in North America. A literature survey revealed no studies on the chemical composition and biological effects of this species. The aim of the present study was to investigate the phenolic content, free radical scavenging and 15-lipoxygenase inhibitory effects of Crataegus succulenta leaf and flower extracts. Total phenolic, flavonoid and proanthocyanidin contents were quantified by spectrophotometric methods. Both extracts were evaluated for their ability to scavenge DPPH, superoxide anion and hydroxyl radicals and to inhibit 15-lipoxygenase activity. There were noticed no striking differences in the total phenolic, flavonoid and proanthocyanidin contents between leaf and flower extracts. Both extracts showed similar 15-lipoxygenase inhibitory effects. Flower extract scavenged more effectively DPPH and superoxide radicals while leave extract was more active against hydroxyl radical. In superoxide anion radical scavenging assay, both extracts were more active than (+)-catechin. In hydroxyl radical scavenging and 15-lipoxygenase inhibition assays, the extracts were only 4-5 times less active than (+)-catechin. The high antioxidant potential of Crataegus succulenta extracts suggest a possible use as ingredients in functional foods for the prevention of oxidative stress-related diseases.

  5. Transition Metal Complexes and Radical Anion Salts of 1,10-Phenanthroline Derivatives Annulated with a 1,2,5-Tiadiazole and 1,2,5-Tiadiazole 1,1-Dioxide Moiety: Multidimensional Crystal Structures and Various Magnetic Properties

    Directory of Open Access Journals (Sweden)

    Yoshiaki Shuku

    2014-01-01

    Full Text Available Advances in the molecular variety and the elucidation of the physical properties of 1,10-phenanthroline annulated with 1,2,5-thiadiazole and 1,2,5-thiadiazole 1,1-dioxide moieties have been achieved, and are described herein. A 1,2,5-thiadiazole compound, [1,2,5]thiadiazolo[3,4-f][1,10]phenanthroline (tdap, was used as a ligand to create multidimensional network structures based on S•••S and S•••N intermolecular interactions. A 1,2,5-thiadiazole 1,1-dioxide compound, [1,2,5] thiadiazolo[3,4-f][1,10]phenanthroline, 1,1-dioxide (tdapO2, was designed to create a stable radical anion, as well as good network structures. Single crystal X-ray structure analyses revealed that transition metal complexes of tdap, and radical anion salts of tdapO2 formed multidimensional network structures, as expected. Two kinds of tdap iron complexes, namely [Fe(tdap2(NCS2] and [Fe(tdap2(NCS2]•MeCN exhibited spin crossover transitions, and their transition temperatures showed a difference of 150 K, despite their similar molecular structures. Magnetic measurements for the tdapO2 radical anion salts revealed that the magnetic coupling constants between neighboring radical species vary from strongly antiferromagnetic (J = −320 K to ferromagnetic (J = 24 K, reflecting the differences in their π overlap motifs.

  6. Potent free radical scavenging activity of propol isolated from Brazilian propolis.

    Science.gov (United States)

    Basnet, P; Matsuno, T; Neidlein, R

    1997-01-01

    We evaluated free radical scavenging activity of the water, methanol and chloroform extracts of propolis in 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical and xanthine-xanthine oxidase (XOD) generated superoxide anion assay systems. The free radical scavenging activity guided fractionation and chemical analysis led to the isolation of a new compound, propol (3-[4-hydroxy-3-(3-oxo-but-1-enyl)-phenyl]-acrylic acid) from the water extract, which was more potent than most common antioxidants such as vitamin C and vitamin E (alpha-tocopherol) in these assay systems.

  7. Interaction between fulvic acids of different origins and active oxygen radicals

    Institute of Scientific and Technical Information of China (English)

    王春霞; 王子健; 彭安; 侯京武; 忻文娟

    1996-01-01

    Using the spin trapping technique, the interaction between fulvic acids (FAs) of different origins and the active oxygen radicals was studied. The active oxygen radicals under study included superoxide anion (O2 · -) produced by xanthine oxidase (XOD) and stimulated polymorphonuclear leukocytes (PMN) of human being and hydroxyl radical ( ·OH) produced from Fenton’s reaction. It has been found that the FAs from both Kaschin-Beck disease (KBD) region and non-KBD region can accelerate the production of ·OH and scavenge O2 ·- . FA from peat can scavenge both O2·- and ·OH. The results show that the behavior of KBD and non-KBD FAs differs clearly from peat FA. It has been concluded that the superoxidation damage of KBD induced by FA is mainly due to hydroxyl radical reaction initiated in biological system.

  8. Mulliken Hush elucidation of the encounter (precursor) complex in intermolecular electron transfer via self-exchange of tetracyanoethylene anion-radical

    Science.gov (United States)

    Rosokha, S. V.; Newton, M. D.; Head-Gordon, M.; Kochi, J. K.

    2006-05-01

    The paramagnetic [1:1] encounter complex (TCNE)2-rad is established as the important precursor in the kinetics and mechanism of electron-transfer for the self-exchange between tetracyanoethylene acceptor ( TCNE) and its radical-anion as the donor. Spectroscopic observation of the dimeric complex (TCNE)2-rad by its intervalence absorption band at the solvent-dependent wavelength of λIV ˜ 1500 nm facilitates the application of Mulliken-Hush theory which reveals the significant electronic interaction extant between the pair of cofacial TCNE moieties with the sizable coupling of HDA = 1000 cm -1. The transient existence of such an encounter complex provides the critical link in the electron-transfer kinetics by lowering the classical Marcus reorganization barrier by the amount of HDA in this strongly adiabatic system. Ab initio quantum-mechanical methods as applied to independent theoretical computations of both the reorganization energy ( λ) and the electronic coupling element ( HDA) confirm the essential correctness of the Mulliken-Hush formalism for fast electron transfer via strongly coupled donor/acceptor encounter complexes.

  9. Pathways of arachidonic acid peroxyl radical reactions and product formation with guanine radicals.

    Science.gov (United States)

    Crean, Conor; Geacintov, Nicholas E; Shafirovich, Vladimir

    2008-02-01

    Peroxyl radicals were derived from the one-electron oxidation of polyunsaturated fatty acids by sulfate radicals that were generated by the photodissociation of peroxodisulfate anions in air-equilibrated aqueous solutions. Reactions of these peroxyl and neutral guanine radicals, also generated by oxidation with sulfate radicals, were investigated by laser kinetic spectroscopy, and the guanine oxidation products were identified by HPLC and mass spectrometry methods. Sulfate radicals rapidly oxidize arachidonic (ArAc), linoleic (LnAc), and palmitoleic (PmAc) acids with similar rate constants, (2-4) x 10 (9) M (-1) s (-1). The C-centered radicals derived from the oxidation of ArAc and LnAc include nonconjugated Rn(.) ( approximately 80%) and conjugated bis-allylic Rba(.) ( approximately 20%) radicals. The latter were detectable in the absence of oxygen by their prominent, narrow absorption band at 280 nm. The Rn(.) radicals of ArAc (containing three bis-allylic sites) transform to the Rba(.) radicals via an intramolecular H-atom abstraction [rate constant (7.5 +/- 0.7) x 10 (4) s (-1)]. In contrast, the Rn(.) radicals of LnAc that contain only one bis-allylic site do not transform intramolecularly to the Rba(.) radicals. In the case of PmAc, which contains only one double bond, the Rba(.) radicals are not observed. The Rn(.) radicals of PmAc rapidly combine with oxygen with a rate constant of (3.8 +/- 0.4) x 10(9) M(-1) s(-1). The Rba(.) radicals of ArAc are less reactive and react with oxygen with a rate constant of (2.2 +/- 0.2) x 10 (8) M (-1) s (-1). The ArAc peroxyl radicals formed spontaneously eliminate superoxide radical anions [rate constant = (3.4 +/- 0.3) x 10 (4) M (-1) s (-1)]. The stable oxidative lesions derived from the 2',3',5'-tri- O-acetylguanosine or 2',3',5'-tri- O-acetyl-8-oxo-7,8-dihydroguanosine radicals and their subsequent reactions with ArAc peroxyl radicals were also investigated. The major products found were the 2,5-diamino-4 H

  10. Formation of Reactive Sulfite-Derived Free Radicals by the Activation of Human Neutrophils: An ESR Study

    Science.gov (United States)

    Ranguelova, Kalina; Rice, Annette B.; Khajo, Abdelahad; Triquigneaux, Mathilde; Garantziotis, Stavros; Magliozzo, Richard S.; Mason, Ronald P.

    2012-01-01

    The objective of the present study is to determine the effect of (bi)sulfite (hydrated sulfur dioxide) on human neutrophils and the ability of these immune cells to produce reactive free radicals due to (bi)sulfite oxidation. Myeloperoxidase (MPO) is an abundant heme protein in neutrophils that catalyzes the formation of cytotoxic oxidants implicated in asthma and inflammatory disorders. In the present study sulfite (•SO3−) and sulfate (SO4•−) anion radicals are characterized with the ESR spin-trapping technique using 5,5-dimethyl-1-pyrroline N-oxide (DMPO) in the reaction of (bi)sulfite oxidation by human MPO and human neutrophils via sulfite radical chain reaction chemistry. After treatment with (bi)sulfite, PMA-stimulated neutrophils produced DMPO-sulfite anion radical, -superoxide, and -hydroxyl radical adducts. The latter adduct probably resulted, in part, from the conversion of DMPO-sulfate to DMPO-hydroxyl radical adduct via a nucleophilic substitution reaction of the radical adduct. This anion radical (SO4•−) is highly reactive and, presumably, can oxidize target proteins to protein radicals, thereby initiating protein oxidation. Therefore, we propose that the potential toxicity of (bi)sulfite during pulmonary inflammation or lung-associated diseases such as asthma may be related to free radical formation. PMID:22326772

  11. Study on the Free Radical Scavenging Activity of Sea Cucumber (Paracaudina chinens var.) Gelatin Hydrolysate

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Gelatin from the sea cucumber (Paracaudina chinens var.) was hydrolyzed by bromelain and the hydrolysate was found to have a high free radical scavenging activity. The hydrolysate was fractionated through an ultrafiltration membrane with 5 kDa molecular weight cutoff (MWCO). The portion (less than 5 kDa) was further separated by Sephadex G-25. The active peak was collected and assayed for free radical scavenging activity. The scavenging rates for superoxide anion radicals (O2·-) and hydroxyl radicals (·OH) of the fraction with the highest activity were 29.02% and 75.41%, respectively. A rabbit liver mitochondrial free radical damage model was adopted to study the free radical scavenging activity of the fraction. The results showed that the sea cucumber gelatin hydrolysate can prevent the damage of rabbit liver and mitochondria.

  12. Possible involvement of an extracellular superoxide dismutase (SodA) as a radical scavenger in poly(cis-1,4-isoprene) degradation.

    Science.gov (United States)

    Schulte, Carina; Arenskötter, Matthias; Berekaa, Mahmoud M; Arenskötter, Quyen; Priefert, Horst; Steinbüchel, Alexander

    2008-12-01

    Gordonia westfalica Kb1 and Gordonia polyisoprenivorans VH2 induce the formation of an extracellular superoxide dismutase (SOD) during poly(cis-1,4-isoprene) degradation. To investigate the function of this enzyme in G. polyisoprenivorans VH2, the sodA gene was disrupted. The mutants exhibited reduced growth in liquid mineral salt media containing poly(cis-1,4-isoprene) as the sole carbon and energy source, and no SOD activity was detectable in the supernatants of the cultures. Growth experiments revealed that SodA activity is required for optimal growth on poly(cis-1,4-isoprene), whereas this enzyme has no effect on aerobic growth in the presence of water-soluble substrates like succinate, acetate, and propionate. This was detected by activity staining, and proof of expression was by antibody detection of SOD. When SodA from G. westfalica Kb1 was heterologously expressed in the sodA sodB double mutant Escherichia coli QC779, the recombinant mutant exhibited increased resistance to paraquat, thereby indicating the functionality of the G. westfalica Kb1 SodA and indirectly protection of G. westfalica cells by SodA from oxidative damage. Both sodA from G. polyisoprenivorans VH2 and sodA from G. westfalica Kb1 coded for polypeptides comprising 209 amino acids and having approximately 90% and 70% identical amino acids, respectively, to the SodA from Mycobacterium smegmatis strain MC(2) 155 and Micrococcus luteus NCTC 2665. As revealed by activity staining experiments with the wild type and the disruption mutant of G. polyisoprenivorans, this bacterium harbors only one active SOD belonging to the manganese family. The N-terminal sequences of the extracellular SodA proteins of both Gordonia species showed no evidence of leader peptides for the mature proteins, like the intracellular SodA protein of G. polyisoprenivorans VH2, which was purified under native conditions from the cells. In G. westfalica Kb1 and G. polyisoprenivorans VH2, SodA probably provides protection

  13. Radical scavenging activity of ribonuclease inhibitor from cow placenta.

    Science.gov (United States)

    Wang, Shuo; Li, Haiping

    2006-05-01

    Cow placenta ribonuclease inhibitor (CPRI) has been purified 5062-fold by affinity chromatography, the product being homogeneous by sodium dodecyl sulfate-gel electrophoresis. The chemiluminescence technique was used to determine the radical scavenging activities of CPRI toward different reactive oxygen species (ROS) including superoxide anion (O2-*), hydroxyl radical (OH*), lipid-derived radicals (R*), and singlet oxygen (1O2). CPRI could effectively scavenge O2-*, OH*, R*, and 1O2 at EC50 of 0.12, 0.008, 0.009, and 0.006 mg/ml, respectively. In addition, the radical scavenging activities of CPRI were higher than those of tea polyphenols, indicating that CPRI is a powerful antioxidant.

  14. Superoxide-dependent hydroxylation by myeloperoxidase.

    Science.gov (United States)

    Kettle, A J; Winterbourn, C C

    1994-06-24

    When stimulated, neutrophils undergo a respiratory burst converting oxygen to superoxide. Although superoxide is critical for microbial killing by phagocytic cells, the precise role it plays has yet to be established. It has been proposed to optimize their production of hypochlorous acid and to be required for the generation of hydroxyl radicals. Superoxide is also involved in the hydroxylation of salicylate by neutrophils. However, the mechanism of this reaction is unknown. We found that neutrophils stimulated with opsonized zymosan hydroxylated salicylate to produce mainly 2,5-dihydroxybenzoate. Its formation was dependent on superoxide and a heme protein but was independent of hydrogen peroxide and hydroxyl radicals. Production of 2,5-dihydroxybenzoate was enhanced by methionine, which scavenges hypochlorous acid. Neutrophils from an individual with myeloperoxidase deficiency hydroxylated salicylate at only 13% of the level of control cells. Purified human myeloperoxidase and xanthine oxidase plus hypoxanthine hydroxylated salicylate to produce 2,5-dihydroxybenzoate. As with neutrophils, the reaction required superoxide but not hydrogen peroxide and was unaffected by hydroxyl radical scavengers. Thus, myeloperoxidase catalyzes superoxide-dependent hydroxylation. This newly recognized reaction may be relevant to the in vivo functions of superoxide and myeloperoxidase.

  15. The Negative Ion Photoelectron Spectrum of meta -Benzoquinone Radical Anion (MBQ •– ): A Joint Experimental and Computational Study

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Bo; Hrovat, David A.; Deng, S. H. M.; Zhang, Jian; Wang, Xue-Bin; Borden, Weston Thatcher

    2014-03-05

    Negative ion photoelectron (NIPE) spectra of the radical anion of meta-benzoquinone (MBQ, m-OC6H4O) have been obtained at 20 K, using both 355 and 266 nm lasers for electron photodetachment. The spectra show well-resolved peaks and complex spectral patterns. The electron affinity of MBQ is determined from the first resolved peak to be 2.875 ±17 0.010 eV. Single-point, CASPT2/aug-cc-pVTZ//CASPT2/ aug-cc-pVDZ calculations predict accurately the positions of the 0-0 bands in the NIPE spectrum for formation of the four lowest electronic states of neutral MBQ from the 2A2 state of MBQ•-. In addition, the Franck-Condon factors that are computed from the CASPT2/aug-cc-pVDZ optimized geometries,vibrational frequencies, and normal mode vectors, successfully simulate the intensities and frequencies of the vibrational peaks in the NIPE spectrum that are associated with each of these electronic states. The successful simulation of the NIPE spectrum of MBQ•- allows the assignment of 3B2 as the ground state of MBQ, followed by the 1B2 and 1A1 electronic states, respectively 9.0 ± 0.2 and 16.6 ± 0.2 kcal/mol higher in energy than the triplet. These experimental energy differences are in good agreement with the calculated values of 9.7 and 15.7 kcal/mol. The relative energies of these two singlet states in MBQ confirm the previous prediction that their relative energies would be reversed from those in meta-benzoquinodimethane (MBQDM, m-CH2C6H4CH2).

  16. Impact of induced levels of specific free radicals and malondialdehyde on chicken semen quality and fertility.

    Science.gov (United States)

    Rui, Bruno R; Shibuya, Fábio Y; Kawaoku, Allison J T; Losano, João D A; Angrimani, Daniel S R; Dalmazzo, Andressa; Nichi, Marcilio; Pereira, Ricardo J G

    2017-03-01

    Over the past decades, scientists endeavored to comprehend oxidative stress in poultry spermatozoa and its relationship with fertilizing ability, lipid peroxidation (LPO), free-radical scavenging systems, and antioxidant therapy. Although considerable progress has been made, further improvement is needed in understanding how specific reactive oxygen species (ROS) and malondialdehyde (MDA, a toxic byproduct of LPO) disrupt organelles in avian spermatozoon. Hence, this study examined functional changes in chicken spermatozoa after incubation with different ROS, and their implications for the fertility. First, semen samples from 14 roosters were individually diluted and aliquoted into five equal parts: control, superoxide anion, hydrogen peroxide (H2O2), hydroxyl radicals, and MDA. After incubation with these molecules, aliquots were analyzed for motility, plasma membrane and acrosome integrity, mitochondrial activity, and LPO and DNA damage. Hydrogen peroxide was more detrimental for sperm motility than hydroxyl radicals, whereas the superoxide anion and MDA exhibited no differences compared with controls. In turn, plasma membrane and acrosome integrity, mitochondrial activity, LPO and DNA integrity rates were only affected by hydroxyl radicals. Thereafter, semen aliquots were incubated under the same conditions and used for artificial insemination. In accordance to our in vitro observations, H2O2 and hydroxyl radicals sharply reduced egg fertility, whereas superoxide anion and MDA only induced slight declines. Thus, chicken sperm function was severely impaired by H2O2 and hydroxyl radicals, but their mechanisms of action seemingly comprise different pathways. Further analysis regarding susceptibility of spermatozoon organelles to specific radicals in other poultry will help us to understand the development of interspecific differences in scavenging systems and to outline more oriented antioxidant approaches.

  17. Literature Review of Research and Application on Superoxide Dismutase%超氧化物歧化酶研究与应用

    Institute of Scientific and Technical Information of China (English)

    张俊艳; 贺阳

    2012-01-01

    Superoxide dismutase is a specific metalloproteinase to clear the superoxide anion radical (O2^**). It could catalyze the disproportionation of superoxide anion radical O2^**- to clear the O2^.**, and it have anti- inflammatory, anti-virus, anti-radiation, anti-aging effect. The source and distribution, purification methods, chemical modification, activity determination and application of the SOD on the article were reviewed, and its production problems and application prospect were analyzed.%超氧化物歧化酶(superoxide dismutase SOD)是一种专一清除超氧阴离子自由基(O2.-)的金属蛋白酶,催化超氧阴离子自由基O2.-发生歧化反应,从而清除O2.-,具有抗炎,抗病毒,抗辐射,抗衰老等作用。对SOD的来源分布、提纯方法、化学修饰、活性测定和生产应用等方面进行了综述,并对其生产问题以及应用前景进行了分析。

  18. A Review on Superoxide Dismutases of Hydrobios%水生生物超氧化物岐化酶的研究进展

    Institute of Scientific and Technical Information of China (English)

    张立颖; 赵萌; 王跃智

    2012-01-01

    Superoxide dismutase(SOD) is an important antioxidase in living creature, existing widely in cytoplasm, mitochondria and chloroplast of eukaryotic and prokaryotic cells, and it can efficiently eliminate superoxide free anion radicals in organism,and prevent organism damage from superoxide free anion radicals. This paper summarizes the research advances on hydrobios( eg. fishes, shrimps, shellfishes and algaes ) superoxide dismutase in terms of types, distribution, structural characteristics, physicochemical properties and gene cloning and expression. Meanwhile, the prospect of its application is also forecasted.%超氧化物歧化酶是生物体内一种重要的抗氧化酶,具有清除生物体内超氧阴离子自由基的作用,可有效地抗御氧自由基对有机体的伤害.概述水生生物(如鱼、虾、贝、藻)SOD的种类、分布、结构特征、理化性质及基因克隆表达的研究进展,并对其应用前景进行展望.

  19. Extracellular production and degradation of superoxide in the coral Stylophora pistillata and cultured Symbiodinium.

    Directory of Open Access Journals (Sweden)

    Eldad Saragosti

    Full Text Available BACKGROUND: Reactive oxygen species (ROS are thought to play a major role in cell death pathways and bleaching in scleractinian corals. Direct measurements of ROS in corals are conspicuously in short supply, partly due to inherent problems with ROS quantification in cellular systems. METHODOLOGY/PRINCIPAL FINDINGS: In this study we characterized the dynamics of the reactive oxygen species superoxide anion radical (O(2(- in the external milieu of the coral Stylophora pistillata. Using a sensitive, rapid and selective chemiluminescence-based technique, we measured extracellular superoxide production and detoxification activity of symbiont (non-bleached and aposymbiont (bleached corals, and of cultured Symbiodinium (from clades A and C. Bleached and non-bleached Stylophora fragments were found to produce superoxide at comparable rates of 10(-11-10(-9 mol O(2(- mg protein(-1 min(-1 in the dark. In the light, a two-fold enhancement in O(2(- production rates was observed in non-bleached corals, but not in bleached corals. Cultured Symbiodinium produced superoxide in the dark at a rate of . Light was found to markedly enhance O(2(- production. The NADPH Oxidase inhibitor Diphenyleneiodonium chloride (DPI strongly inhibited O(2(- production by corals (and more moderately by algae, possibly suggesting an involvement of NADPH Oxidase in the process. An extracellular O(2(- detoxifying activity was found for bleached and non-bleached Stylophora but not for Symbiodinium. The O(2(- detoxifying activity was partially characterized and found to resemble that of the enzyme superoxide dismutase (SOD. CONCLUSIONS/SIGNIFICANCE: The findings of substantial extracellular O(2(- production as well as extracellular O(2(- detoxifying activity may shed light on the chemical interactions between the symbiont and its host and between the coral and its environment. Superoxide production by Symbiodinium possibly implies that algal bearing corals are more susceptible to an

  20. Exploitation of the photochromic nitroprusside anion [ FeNO(CN){5}] 2- as counterion for constructing molecular conductors: The first radical cation salts based on BDH-TTP and the amide functionalized derivatives of EDT-TTF

    Science.gov (United States)

    Shibaeva, R.; Khasanov, S.; Zorina, L.; Simonov, S.; Shevyakova, I.; Kushch, L.; Buravov, L.; Yagubskii, E.; Baudron, S.; Mézière, C.; Batail, P.; Canadell, E.; Yamada, J.

    2004-04-01

    The radical cation salts based on BDH-TTP and the mono- and diamide functionalized derivatives of EDT-TTF with the double charged nitroprusside anion [ FeNO(CN){5}] 2- (NP): kappa -(BDH-TTP){4}[NP]C{6}H{5}NO{2} (1), kappa -(BDH-TTP){4}[NP] (2), (BDH-TTP){2}[NP] (3), α -[ EDT-TTF-CONH{2}] {4}[NP] (4), β -[ EDT-TTF-(CONH{2})2] {2}[NP]{0.5}(C{6}H{5}NO{2})0.5 (5) have been synthesized. The crystal structures and transport properties of 1 5, as well as electronic band structures of 1and 2 have been studied. Key words. organic conductors based on radical cation salts X-ray and band structure conductivity.

  1. L -propionyl-carnitine as superoxide scavenger, antioxidant, and DNA cleavage protector.

    Science.gov (United States)

    Vanella, A; Russo, A; Acquaviva, R; Campisi, A; Di Giacomo, C; Sorrenti, V; Barcellona, M L

    2000-01-01

    L-Propionylcarnitine, a propionyl ester of L-carnitine, increases the intracellular pool of L-carnitine. It exhibits a high affinity for the enzyme carnitine acetyltransferase (CAT) and, thus, is readily converted into propionyl-coenzyme A and free carnitine. It has been reported that L-propionylcarnitine possesses a protective action against heart ischemia-reperfusion injury; however, the antioxidant mechanism is not yet clear. L-Propionylcarnitine might reduce the hydroxyl radical production in the Fenton system, by chelating the iron required for the generation of hydroxyl radicals. To obtain a better insight into the antiradical mechanism of L-propionylcarnitine, the present research analyzed the superoxide scavenging capacity of L-propionylcarnitine and its effect on linoleic acid peroxidation. In addition, the effect of L-propionylcarnitine against DNA cleavage was estimated using pBR322 plasmid. We found that L-propionylcarnitine showed a dose-dependent free-radical scavenging activity. In fact, it was able to scavenge superoxide anion, to inhibit the lipoperoxidation of linoleic acid, and to protect pBR322 DNA from cleavage induced by H2O2 UV-photolysis.

  2. Leukocyte oxygen radical production determines disease severity in the recurrent Guillain-Barré syndrome

    Directory of Open Access Journals (Sweden)

    Bergström Tomas

    2010-08-01

    Full Text Available Abstract Background The recurrent Guillain-Barré syndrome (RGBS is characterized by at least two GBS episodes with intervening remission. In a previous study of monophasic GBS, we reported that the magnitude of oxygen radical production ("respiratory burst" in peripheral blood leukocytes was inversely correlated to disease severity. The present study sought to establish a similar correlation in patients with RGBS. Methods Oxygen radical production in leukocytes was induced by formyl-Met-Leu-Phe (fMLF, Trp-Lys-Tyr-Met-Val-Met-NH2 (WKYMVM, or phorbol myristate acetate (PMA and assessed by quantifying superoxide anion formed by the leukocyte NADPH oxidase. Results Disease severity, assessed using the MRC score, was negatively correlated to superoxide anion production triggered by fMLF or WKYMVM (p = 0.001 and 0.002, respectively; n = 10. Superoxide anion production also was significantly lower in RGBS patients with incomplete recovery after stimulation with fMLF (p = 0.004 or WKYMVM (p = 0.003. Conclusion We conclude that a lower respiratory burst in leukocytes is strongly associated with a severe course of RGBS.

  3. Leukocyte oxygen radical production determines disease severity in the recurrent Guillain-Barré syndrome.

    Science.gov (United States)

    Mossberg, Natalia; Andersen, Oluf; Nordin, Magnus; Nilsson, Staffan; Svedhem, Ake; Bergström, Tomas; Hellstrand, Kristoffer; Movitz, Charlotta

    2010-08-08

    The recurrent Guillain-Barré syndrome (RGBS) is characterized by at least two GBS episodes with intervening remission. In a previous study of monophasic GBS, we reported that the magnitude of oxygen radical production ("respiratory burst") in peripheral blood leukocytes was inversely correlated to disease severity. The present study sought to establish a similar correlation in patients with RGBS. Oxygen radical production in leukocytes was induced by formyl-Met-Leu-Phe (fMLF), Trp-Lys-Tyr-Met-Val-Met-NH2 (WKYMVM), or phorbol myristate acetate (PMA) and assessed by quantifying superoxide anion formed by the leukocyte NADPH oxidase. Disease severity, assessed using the MRC score, was negatively correlated to superoxide anion production triggered by fMLF or WKYMVM (p = 0.001 and 0.002, respectively; n = 10). Superoxide anion production also was significantly lower in RGBS patients with incomplete recovery after stimulation with fMLF (p = 0.004) or WKYMVM (p = 0.003). We conclude that a lower respiratory burst in leukocytes is strongly associated with a severe course of RGBS.

  4. Magnetoreception through Cryptochrome may involve superoxide

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Schulten, Klaus

    2009-01-01

    pair-based reaction in the photoreceptor cryptochrome that reduces the protein's flavin group from its signaling state FADH$^bullet$ to the inactive state FADH$^–$ (which reacts to the likewise inactive FAD) by means of the superoxide radical, O2$^$. We argue that the spin dynamics in the suggested...

  5. Revisiting the reactions of superoxide with glutathione and other thiols.

    Science.gov (United States)

    Winterbourn, Christine C

    2016-04-01

    The reaction between GSH and superoxide has long been of interest in the free radical biology. Early studies were confusing, as some reports suggested that the reaction could be a major pathway for superoxide removal whereas others questioned whether it happened at all. Further research by several investigators, including Helmut Sies, was required to clarify this complex reaction. We now know that superoxide does react with GSH, but the reaction is relatively slow and occurs mostly by a chain reaction that consumes oxygen and regenerates superoxide. Most of the GSH is converted to GSSG, with a small amount of sulfonic acid. As shown by Sies and colleagues, singlet oxygen is a by-product. Although removal of superoxide by GSH may be a minor pathway, GSH and superoxide have a strong physiological connection. GSH is an efficient free radical scavenger, and when it does so, thiyl radicals are generated. These further react to generate superoxide. Therefore, radical scavenging by GSH and other thiols is a source of superoxide and hydrogen peroxide, and to be an antioxidant pathway, there must be efficient removal of these species.

  6. Antioxidant capacity and angiotensin I converting enzyme inhibitory activity of a melon concentrate rich in superoxide dismutase.

    Science.gov (United States)

    Carillon, Julie; Del Rio, Daniele; Teissèdre, Pierre-Louis; Cristol, Jean-Paul; Lacan, Dominique; Rouanet, Jean-Max

    2012-12-01

    Antioxidant capacity and angiotensin 1-converting enzyme (ACE) inhibitory activity of a melon concentrate rich in superoxide dismutase (SOD-MC) were investigated in vitro. The total antioxidant capacity (TAC) was measured by the Trolox equivalent antioxidant capacity assay (TEAC), the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical assay, and the ferric reducing antioxidant power assay (FRAP). The ability of the extract to scavenge three specific reactive oxygen species (superoxide radical anion (O(2)(-)), hydroxyl radical (HO()) and hydrogen peroxide (H(2)O(2))) was also investigated in order to better evaluate its antioxidant properties. Even if the measures of TAC were relatively low, results clearly established an antioxidant potential of SOD-MC that exhibited the highest radical-scavenging activity towards O(2)(-), with a IC(50) 12-fold lower than that of H(2)O(2) or HO(). This lets hypothesis that the antioxidant potential of SOD-MC could be mainly due to its high level of SOD. Moreover, for the first time, an ACE inhibitory activity of SOD-MC (IC(50)=2.4±0.1mg/mL) was demonstrated, showing that its use as a functional food ingredient with potential preventive benefits in the context of hypertension may have important public health implications and should be carefully considered.

  7. Oxidative catalysis using the stoichiometric oxidant as a reagent: an efficient strategy for single-electron-transfer-induced tandem anion-radical reactions.

    Science.gov (United States)

    Kafka, František; Holan, Martin; Hidasová, Denisa; Pohl, Radek; Císařová, Ivana; Klepetářová, Blanka; Jahn, Ullrich

    2014-09-01

    Oxidative single-electron transfer-catalyzed tandem reactions consisting of a conjugate addition and a radical cyclization are reported, which incorporate the mandatory terminal oxidant as a functionality into the product.

  8. Free radicals and antioxidant systems in reflux esophagitis and Barrett's esophagus

    Institute of Scientific and Technical Information of China (English)

    Pilar Jiménez; Elena Piazuelo; M. Teresa Sánchez; Javier Ortego; Fernando Soteras; Angel Lanas

    2005-01-01

    AIM: Experimental studies suggest that free radicals are involved in acid and pepsin-induced damage of esophageal mucosa. The profile and balance between free radicals and antioxidant systems in human esophagitis are unknown. METHODS: Superoxide anion and its powerful oxidant reaction with nitric oxide (peroxynitrite) generation were determined in esophageal mucosal biopsies from 101 patients with different gastro-esophageal reflux diseases and 28 controls. Activity of both superoxide dismutase (SOD) and catalase, and reduced glutathione (GSH) levels,were also assessed. Expression of Cu,ZnSOD, MnSOD and tyrosine-nitrated MnSOD were analyzed by Western blot and/or immunohistochemistry.RESULTS: The highest levels of superoxide anion generation were found in patients with severe lesions of esophagitis. Peroxynitrite generation was intense in Barrett's biopsies, weaker in esophagitis and absent/weak in normal mucosa. Expression of Cu,ZnSOD and MnSOD isoforms were present in normal mucosa and increased according to the severityof the lesion, reaching the highest level in Barrett's esophagus. However, SOD mucosal activity significantly decreased in patients with esophagitis and Barrett's esophagus, which was, at least in part, due to nitration of its tyrosine residues. Catalase activity and GSH levels were significanUy increased in mucosal specimens from patients with esophagitis and/or Barrett's esophagus.CONCLUSION: A decrease in SOD antioxidant activity leading to increased mucosal levels of superoxide anion and peroxynitrite radicals may contribute to the development of esophageal damage and Barrett's esophagus in patients with gastroesophageal reflux. Administration of SOD may be a therapeutic target in the treatment of patients with esophagitis and Barrett's esophagus.

  9. The Effect of Nitrogen-Doped ATO Nanotubes on Radical Multiplication of Buffer Media by Visible Light Photocatalysis Rather UV

    Directory of Open Access Journals (Sweden)

    Kan-Hung Hu

    2012-01-01

    Full Text Available The use of TiO2 in photodynamic therapy for the treatment of cancer has generally been studied in cultured cancer cells in serum-containing RPMI 1640 medium under visible light application rather than ultraviolet (UV light. An ordered channel array of N-doped anodic titanium dioxide (ATO has been successfully made for visible light application. ATO nanotubes in the anatase form with a length of 10 μm are more effective than nanotubes of 1.8 μm in length as a photocatalyst for radical multiplication in buffer solution by generating hydroxyl radicals and superoxide radical anions under UV-A exposure. Only the N-doped ATO is applicable to visible light photocatalysis for radical multiplication in RPMI 1640+1% FBS and acrylamide, a free radical carrier.

  10. THE EFFECTS OF S-3-1 ON LIPID PEROXIDATION AND SCAVENGING FREE RADICALS IN VITRO

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    S-3-1 is a simplified synthetic analogue of the active principle of Salvia miltiorrhioza. Electron spin resonance spectrometry using 5,5′-dimethyl-1-pyrroline-N-oxide as a scavenger of free radicals indicated that 200 μg/ml of S-3-1 scavenged 1,1-diphenyl-2-picrylhydrazyl radicals completely. 25μg/ml of this compound quenched 100% of superoxide anion and a concentration of 250 μg/ml of S-3-1 quenched 63% of hydroxyl radicals. It was also shown that 3.56 mg/ml of S-3-1 could inhibit lipid peroxidation in microsome fraction from rat liver induced by FeSO4 and cysteine. These results show that S-3-1 is an effective antioxidant by scavenging free radicals.

  11. The role of anions on the indoor air quality; De rol van negatieve ionen op de binnenluchtkwaliteit

    Energy Technology Data Exchange (ETDEWEB)

    Havermans, J. [Afdeling Energie, Comfort en Binnenmilieu, TNO Bouw en Onderzoek, Delft (Netherlands)

    2010-11-15

    Anions may contribute to a more comfortable indoor environment. Even a simple apparatus as a lamp with semi conductor technique produces easily anions. Such ions will react with particles forming agglomerates that will precipitate. Also a reaction with oxygen and moist will result in the formation of a superoxide radical and peroxides. These radicals easily react with e.g. organic volatiles and possible also with spores and allergens. Depending on the concentration of the radicals, these compounds can be deteriorated fully. However, as a potential negative side effect the radicals can produce irritating substances by reaction with chemicals in the air. It is not clear yet if all cleaners, based on ionization, will cause this effect. Therefore more research is needed. [Dutch] Negatieve ionen (anionen) in de lucht kunnen een belangrijke bijdrage leveren aan een comfortabeler binnenmilieu en kunnen op een eenvoudige wijze worden geproduceerd. Bijvoorbeeld met lamp waarbij naast verlichting ook via (smd) halfgeleidertechniek negatieve ionen worden gevormd. Negatieve ionen reageren met deeltjes waardoor deze clusteren en deze uit de binnenlucht worden verwijderd. Ook kunnen ze met zuurstof en vocht reageren, waarbij reactief superoxide en peroxides worden gevormd. Deze radicalen zijn verantwoordelijk voor het verwijderen van bijvoorbeeld ongewenste geuren en mogelijk ook allergenen en schimmels. Ze kunnen ook als negatief bijeffect potentieel irriterende stoffen vormen door reactie met chemicalien in de lucht. Of dit het geval is met alle op ionisatie gebaseerde luchtzuiveringsapparaten dient nader te worden onderzocht.

  12. Free radicals and antioxidants at a glance using EPR spectroscopy.

    Science.gov (United States)

    Spasojević, Ivan

    2011-01-01

    The delicate balance between the advantageous and detrimental effects of free radicals is one of the important aspects of human (patho)physiology. The controlled production of reactive oxygen and nitrogen species has an essential role in the regulation of various signaling switches. On the other hand, imbalanced generation of radicals is highly correlated with the pathogenesis of many diseases which require the application of selected antioxidants to regain the homeostasis. In the era of growing interest for redox processes, electron paramagnetic resonance (EPR) spectroscopy is arguably the best-suited technique for such research due to its ability to provide a unique insight into the world of free radicals and antioxidants. Herein, I present the principles of EPR spectroscopy and the applications of this method in assessing: (i) the oxidative status of biological systems, using endogenous long-lived free radicals (ascorbyl radical (Asc(•)), tocopheroxyl radical (TO(•)), melanin) as markers; (ii) the production of short-lived radicals (hydroxyl radical (OH(•)), superoxide radical anion (O(2)(•-)), sulfur- and carbon-centered radicals), which are implicated in both, oxidative stress and redox signaling; (iii) the metabolism of nitric oxide (NO(•)); (iv) the antioxidative properties of various drugs, compounds, and natural products; (v) other redox-relevant parameter. Besides giving a comprehensive survey of up-to-date literature, I also provide illustrative examples in sufficient detail to provide a means to exploit the potential of EPR in biochemical/physiological/medical research. The emphasis is on the features and characteristics (both positive and negative) relevant for EPR application in clinical sciences. My aim is to encourage fellow colleagues interested in free radicals and antioxidants to expand their base knowledge or methods used in their laboratories with data acquired by EPR or some of the EPR techniques outlined in this review, in order to

  13. Detection of superoxide production in stimulated and unstimulated living cells using new cyclic nitrone spin traps.

    Science.gov (United States)

    Abbas, Kahina; Hardy, Micael; Poulhès, Florent; Karoui, Hakim; Tordo, Paul; Ouari, Olivier; Peyrot, Fabienne

    2014-06-01

    Reactive oxygen species (ROS), including superoxide anion and hydrogen peroxide (H2O2), have a diverse array of physiological and pathological effects within living cells depending on the extent, timing, and location of their production. For measuring ROS production in cells, the ESR spin trapping technique using cyclic nitrones distinguishes itself from other methods by its specificity for superoxide and hydroxyl radical. However, several drawbacks, such as the low spin trapping rate and the spontaneous and cell-enhanced decomposition of the spin adducts to ESR-silent products, limit the application of this method to biological systems. Recently, new cyclic nitrones bearing a triphenylphosphonium (Mito-DIPPMPO) or a permethylated β-cyclodextrin moiety (CD-DIPPMPO) have been synthesized and their spin adducts demonstrated increased stability in buffer. In this study, a comparison of the spin trapping efficiency of these new compounds with commonly used cyclic nitrone spin traps, i.e., 5,5-dimethyl-1-pyrroline N-oxide (DMPO), and analogs BMPO, DEPMPO, and DIPPMPO, was performed on RAW 264.7 macrophages stimulated with phorbol 12-myristate 13-acetate. Our results show that Mito-DIPPMPO and CD-DIPPMPO enable a higher detection of superoxide adduct, with a low (if any) amount of hydroxyl adduct. CD-DIPPMPO, especially, appears to be a superior spin trap for extracellular superoxide detection in living macrophages, allowing measurement of superoxide production in unstimulated cells for the first time. The main rationale put forward for this extreme sensitivity is that the extracellular localization of the spin trap prevents the reduction of the spin adducts by ascorbic acid and glutathione within cells.

  14. Theoretical and Experimental Studies of the Spin Trapping of Inorganic Radicals by 5,5-Dimethyl-1-Pyrroline N-Oxide (DMPO). 3. Sulfur Dioxide, Sulfite and Sulfate Radical Anions

    Science.gov (United States)

    Zamora, Pedro L.; Villamena, Frederick A.

    2012-01-01

    Radical forms of sulfur dioxide (SO2), sulfite (SO32−), sulfate (SO42−), and their conjugate acids are known to be generated in vivo through various chemical and biochemical pathways. Oxides of sulfur are environmentally pervasive compounds and are associated with a number of health problems. There is growing evidence that their toxicity may be mediated by their radical forms. Electron paramagnetic resonance (EPR) spin trapping using the commonly used spin trap, 5,5-dimethyl-1-pyrroline N-oxide (DMPO), has been employed in the detection of SO3•− and SO4•−. The thermochemistries of SO2•−, SO3•−, SO4•−, and their respective conjugate acids addition to DMPO were predicted using density functional theory (DFT) at the PCM/B3LYP/6-31+G**//B3LYP/6-31G* level. No spin adduct was observed for SO2•− by EPR but an S-centered adduct was observed for SO3•− and an O-centered adduct for SO4•−. Determination of adducts as S- or O-centered was made via comparison based on qualitative trends of experimental hfcc’s with theoretically calculated ones. The thermodynamics of the non-radical addition of SO32− and HSO3− to DMPO followed by conversion to the corresponding radical adduct via the Forrester-Hepburn mechanism was also calculated. Adduct acidities and decomposition pathways were investigated as well, including an EPR experiment using H217O to determine the site of hydrolysis of O-centered adducts. The mode of radical addition to DMPO is predicted to be governed by several factors, including spin population density, and geometries stabilized by hydrogen bonds. The thermodynamic data supports evidence for the radical addition pathway over the nucleophilic addition mechanism. PMID:22668066

  15. Requirements for superoxide-dependent tyrosine hydroperoxide formation in peptides

    DEFF Research Database (Denmark)

    Winterbourn, Christine C; Parsons-Mair, Helena N; Gebicki, Silvia

    2004-01-01

    Superoxide reacts rapidly with other radicals, but these reactions have received little attention in the context of oxidative stress. For tyrosyl radicals, reaction with superoxide is 3-fold faster than dimerization, and forms the addition product tyrosine hydroperoxide. We have explored structural...... requirements for hydroperoxide formation using tyrosine analogues and di- and tri-peptides. Superoxide and phenoxyl radicals were generated using xanthine oxidase, peroxidase and the respective tyrosine derivative, or by gamma-radiation. Peroxides were measured using FeSO4/Xylenol Orange. Tyrosine and tyramine...... losses, indicated that, in the absence of a free amino group, reaction with superoxide resulted primarily in restitution of the parent compound. With dipeptides, hydroperoxides were formed only on N-terminal tyrosines. However, adjacent lysines promoted hydroperoxide formation, as did addition of free...

  16. Lecithinized copper,zinc-superoxide dismutase as a protector against doxorubicin-induced cardiotoxicity in mice.

    NARCIS (Netherlands)

    Hartog, den GJ; Haenen, GR; Boven, E.; Vijgh, van der WJ

    2004-01-01

    Production of superoxide radicals from doxorubicin is widely accepted to be the cause of the cardiotoxicity induced by this antitumor agent. Pretreatment with superoxide dismutase could improve the therapeutic application. Aim of the present study was to determine whether lecithinized superoxide

  17. Comparison of the radical scavenging potential of polar and lipidic fractions of olive oil and other vegetable oils under normal conditions and after thermal treatment.

    Science.gov (United States)

    Valavanidis, Athanasios; Nisiotou, Christala; Papageorgiou, Yiannis; Kremli, Ioulia; Satravelas, Nikolaos; Zinieris, Nikolaos; Zygalaki, Helen

    2004-04-21

    The antioxidant activity (IC(50)) of extra virgin olive oil (EVOO), commercial olive oil, and other vegetable oils (soybean, sunflower, and corn oil) was determined by UV-vis and by electron paramagnetic resonance (EPR) spectroscopy of the stable radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). Also, we studied the antioxidant activity of the methanol soluble phase (methanolic, MF) and the nonsoluble phase (lipidic, LF) of oils by the same methods. Similarly, we studied the effect of heating on the antioxidant activity at 160 and 190 degrees C. Also, the MF, containing the polyphenolic substances, was used for measurements of the radical scavenging capacity toward the most important oxygen free radicals, superoxide anion (O(2)(*)(-)) and hydroxyl (HO(*)) radicals. Results showed that soybean oil and EVOO had the highest antioxidant potential and thermal stability. In the case of soybean oil, the antioxidant capacity is the result of its high content of gamma- and delta-tocopherols (with the highest antioxidant capacity and thermostabilities), whereas in EVOO, the antioxidant potential is the result of the combination of specific antioxidant polyphenols, which are acting additionally as effective stabilizers of alpha-tocopherol. The high content of EVOO in tyrosol, hydrotyrosol, and oleuropein and other polyphenolics with radical scavenging abilities toward superoxide anion and hydroxyl radical suggests that olive oil possesses biological properties that could partially account for the observed beneficial health effects of the Mediterranean diet.

  18. A lab-on-a-molecule for anions in aqueous solution: using Kolbe electrolysis and radical methylation at iridium for sensing.

    Science.gov (United States)

    Schmittel, Michael; Qinghai, Shu

    2012-03-11

    Iridium complex [(pq)(2)IrCl](2) (1) is established as a quantitatively operating lab-on-a-molecule in aqueous media at physiological pH. Acting as a chemodosimeter, 1 uses two channels, PL and ECL, for the detection of cyanide and acetate, with the former undergoing nucleophilic attack and the latter Kolbe electrolysis and radical-metal combination. This journal is © The Royal Society of Chemistry 2012

  19. Piper betle shows antioxidant activities, inhibits MCF-7 cell proliferation and increases activities of catalase and superoxide dismutase

    Directory of Open Access Journals (Sweden)

    Abrahim Noor

    2012-11-01

    Full Text Available Abstract Background Breast cancer is the most common form of cancer and the focus on finding chemotherapeutic agents have recently shifted to natural products. Piper betle is a medicinal plant with various biological activities. However, not much data is available on the anti-cancer effects of P. betle on breast cancer. Due to the current interest in the potential effects of antioxidants from natural products in breast cancer treatment, we investigated the antioxidant activities of the leaves of P. betle and its inhibitory effect on the proliferation of the breast cancer cell line, MCF-7. Methods The leaves of P. betle were extracted with solvents of varying polarities (water, methanol, ethyl acetate and hexane and their phenolic and flavonoid content were determined using colorimetric assays. Phenolic composition was characterized using HPLC. Antioxidant activities were measured using FRAP, DPPH, superoxide anion, nitric oxide and hyroxyl radical scavenging assays. Biological activities of the extracts were analysed using MTT assay and antioxidant enzyme (catalase, superoxide dismutase, glutathione peroxidase assays in MCF-7 cells. Results Overall, the ethyl acetate extract showed the highest ferric reducing activity and radical scavenging activities against DPPH, superoxide anion and nitric oxide radicals. This extract also contained the highest phenolic content implying the potential contribution of phenolics towards the antioxidant activities. HPLC analyses revealed the presence of catechin, morin and quercetin in the leaves. The ethyl acetate extract also showed the highest inhibitory effect against the proliferation of MCF-7 cells (IC50=65 μg/ml. Treatment of MCF-7 cells with the plant extract increased activities of catalase and superoxide dismutase. Conclusions Ethyl acetate is the optimal solvent for the extraction of compounds with antioxidant and anti-proliferative activities. The increased activities of catalase and superoxide

  20. Antioxidative protection by melatonin: multiplicity of mechanisms from radical detoxification to radical avoidance.

    Science.gov (United States)

    Hardeland, Rüdiger

    2005-07-01

    Melatonin has been shown to protect against oxidative stress in various, highly divergent experimental systems. There are many reasons for its remarkable protective potential. Signaling effects comprise the upregulation of antioxidant enzymes, such as superoxide dismutases, peroxidases, and enzymes of glutathione supply, down-regulation of prooxidant enzymes, such as nitric oxide synthases and lipoxygenases, and presumably also the control of quinone reductase 2. Other mechanisms are based on direct interactions with several reactive oxygen and nitrogen species. Among these reactions, the capacity of easily undergoing single-electron transfer reactions is of particular importance. Electron donation by melatonin is not only an aspect of direct radical scavenging, but additionally represents the basis for formation of the protective metabolites AFMK (N1-ace-tyl-N2-formyl-5-methoxykynuramine) and AMK (N1-acetyl-5-methoxykynuramine). Recent investigations on mitochondrial metabolism indicate that melatonin as well as AMK are capable of supporting the electron flux through the respiratory chain, of preventing the breakdown of the mitochondrial membrane potential, and of decreasing electron leakage, thereby reducing the formation of superoxide anions. Radical avoidance is a new line of investigation, which exceeds mitochondrial actions and also comprises antiexcitatory effects and contributions to the maintenance of internal circadian phase relationships.

  1. The Scavenging of Free Radical and Oxygen Species Activities and Hydration Capacity of Collagen Hydrolysates from Walleye Pollock (Theragra chalcogramma) Skin

    Institute of Scientific and Technical Information of China (English)

    ZHUANG Yongliang; LI Bafang; ZHAO Xue

    2009-01-01

    Fish skin collagen hydrolysates (FSCH) were prepared from walleye pollock (Theragra chalcogramma) using a mixture of enzymes, namely trypsin and flavourzyme. The degree of hydrolysis of the skin collagen was 27.3%. FSCH was mainly composed of low-molecular-weight peptides and the relative proportion of <1000Da fraction was 70.6%. Free radical and oxygen species scavenging activities of FSCH were investigated in four model systems, including diphenylpicrylhy-drazyl radical (DPPH), superox-ide anion radical, hydroxyl radical and hydrogen peroxide model, and compared with that of a native antioxidant, reduced glutathione (GSH). FSCH was also evaluated by water-absorbing and water-holding capacity. The results showed that FSCH was able to scav-enge free radical and oxygen species significantly and to enhance water-absorbing and water-holding capacity remarkably. Therefore, FSCH may have potential applications in the medicine and food industries.

  2. Senescence marker protein-30/superoxide dismutase 1 double knockout mice exhibit increased oxidative stress and hepatic steatosis

    Directory of Open Access Journals (Sweden)

    Yoshitaka Kondo

    2014-01-01

    Full Text Available Superoxide dismutase 1 (SOD1 is an antioxidant enzyme that converts superoxide anion radicals into hydrogen peroxide and molecular oxygen. The senescence marker protein-30 (SMP30 is a gluconolactonase that functions as an antioxidant protein in mammals due to its involvement in ascorbic acid (AA biosynthesis. SMP30 also participates in Ca2+ efflux by activating the calmodulin-dependent Ca2+-pump. To reveal the role of oxidative stress in lipid metabolism defects occurring in non-alcoholic fatty liver disease pathogenesis, we generated SMP30/SOD1-double knockout (SMP30/SOD1-DKO mice and investigated their survival curves, plasma and hepatic lipid profiles, amounts of hepatic oxidative stress, and hepatic protein levels expressed by genes related to lipid metabolism. While SMP30/SOD1-DKO pups had no growth retardation by 14 days of age, they did have low plasma and hepatic AA levels. Thereafter, 39% and 53% of male and female pups died by 15–24 and 89 days of age, respectively. Compared to wild type, SMP30-KO and SOD1-KO mice, by 14 days SMP30/SOD1-DKO mice exhibited: (1 higher plasma levels of triglyceride and aspartate aminotransferase; (2 severe accumulation of hepatic triglyceride and total cholesterol; (3 higher levels of superoxide anion radicals and thiobarbituric acid reactive substances in livers; and (4 decreased mRNA and protein levels of Apolipoprotein B (ApoB in livers – ApoB is an essential component of VLDL secretion. These results suggest that high levels of oxidative stress due to concomitant deficiency of SMP30 and/or AA, and SOD1 cause abnormal plasma lipid metabolism, hepatic lipid accumulation and premature death resulting from impaired VLDL secretion.

  3. Simultaneous monitoring of superoxides and intracellular calcium ions in neutrophils by chemiluminescence and fluorescence: evaluation of action mechanisms of bioactive compounds in foods.

    Science.gov (United States)

    Kazumura, Kimiko; Sato, Yukiko; Satozono, Hiroshi; Koike, Takashi; Tsuchiya, Hiroshi; Hiramatsu, Mitsuo; Katsumata, Masakazu; Okazaki, Shigetoshi

    2013-10-01

    We have developed a measuring system for simultaneous monitoring of chemiluminescence and fluorescence, which indicate respectively, (i) generation of superoxide anion radicals (O2(-•)) and (ii) change in the intracellular calcium ion concentration ([Ca(2+)]i) of neutrophils triggered by the mechanism of innate immune response. We applied this measuring system for establishing a method to distinguish between anti-inflammatory actions and antioxidant actions caused by bioactive compounds. We evaluated anti-inflammatory agents (zinc ion [Zn(2+)] and ibuprofen) and antioxidants (superoxide dismutase [SOD] and ascorbic acid). It was shown that ibuprofen and Zn(2+) were anti-inflammatory while SOD and ascorbic acid were anti-oxidative. We conclude that it is possible to determine the mechanism of action of bioactive compounds using this method.

  4. The generation of free radicals in the development of grey mould on poinsettia leaves

    Directory of Open Access Journals (Sweden)

    Beata Kułek

    2013-12-01

    Full Text Available Participation of superoxide anion and hydroxyl radical as well as lipoxygenase (LOX activity and chemiluminescence in the development of grey mould on poinsettia leaves of the cvs.: Coco White - moderately resistant and Malibu Red - susceptible to Botryotinia fuckeliana (B. cinerea were investigated. In both poinsettia cultivars, the level of superoxide anion radical increased with the disease development. On later dates following inoculation, the content of O2.- in the diseased leaf areas of the susceptible cultivar was 2 - fold larger than in grey mould symptom areas of the moderately resistant cultivar. The postinfection generation of a strongly reactive hydroxyl radical was found in the cultivar susceptible to the pathogen. The level of .- OH in the last hours afier inoculation was 10 fold higher in grey mould spots than in healthy senescing leaves of that cultivar. Tlie activity of LOX exhibited opposite tendencies of changes in the both genotypes examined after the infection. In the first hours after inoculation, the enzyme activity was Low, whereas after 3rt day it significantly increased in diseased leaf areas and in their surroundings. However, in the moderately resistant cultivar the activity of lipoxygenase thoughout the first 3 days of the disease activity was relatively high and then decreased. Poinsettia leaves infected with B.cinerea emitted chemiluminescence. Kinetics and the intensity of ultraweak chemiluminescence depended on the cultivars of poinsettia and on the degree of the disease development. The postinfection increase of chemiluminescence was particularly visible in the zone surrounding diseased areas in the susceptible cultivar.

  5. The role of free radicals in traumatic brain injury.

    Science.gov (United States)

    O'Connell, Karen M; Littleton-Kearney, Marguerite T

    2013-07-01

    Traumatic brain injury (TBI) is a significant cause of death and disability in both the civilian and the military populations. The primary impact causes initial tissue damage, which initiates biochemical cascades, known as secondary injury, that expand the damage. Free radicals are implicated as major contributors to the secondary injury. Our review of recent rodent and human research reveals the prominent role of the free radicals superoxide anion, nitric oxide, and peroxynitrite in secondary brain injury. Much of our current knowledge is based on rodent studies, and the authors identified a gap in the translation of findings from rodent to human TBI. Rodent models are an effective method for elucidating specific mechanisms of free radical-induced injury at the cellular level in a well-controlled environment. However, human TBI does not occur in a vacuum, and variables controlled in the laboratory may affect the injury progression. Additionally, multiple experimental TBI models are accepted in rodent research, and no one model fully reproduces the heterogeneous injury seen in humans. Free radical levels are measured indirectly in human studies based on assumptions from the findings from rodent studies that use direct free radical measurements. Further study in humans should be directed toward large samples to validate the findings in rodent studies. Data obtained from these studies may lead to more targeted treatment to interrupt the secondary injury cascades.

  6. Studies on structures and electron affinities of the simplest alkyl dithio radicals and their anions with gaussian-3 theory and density functional theory.

    Science.gov (United States)

    Gao, Aifang; Du, Hongli; Li, Aiguo; Pei, Huiyi

    2013-06-01

    The equilibrium geometries and electron affinities of the R-SS/R-SS(-)(R=CH₃, C₂H₅, n-C₃H7, i-C₃H₇, n-C₄H₉, t-C₄H₉, n-C₅H₁₁) species have been studied using the higher level of the Gaussian-3(G3) theory and 21 carefully calibrated pure and hybrid density functionals (five generalized gradient approximation (GGA) methods, seven hybrid GGAs, three meta GGA methods, and six hybrid meta GGAs) in conjunction with diffuse function augmented double-ζ plus polarization (DZP++) basis sets. The geometries are fully optimized with each method and discussed. The reliable adiabatic electron affinity has been presented by means of the high level of G3 technique. With the DZP++ DFT method, three measures of neutral/anion energy differences reported in this work are the adiabatic electron affinity, the vertical electron affinity, and the vertical detachment energy. The adiabatic electron affinities, obtained at the BP86, M05-2X, B3LYP, M06, B98, M06-2X, mPW1PW91, HCTH, B97-1, M05, PBE1PBE, and VSXC methods, are in agreement with the G3 results. These methods perform better for EA prediction and are considered to be reliable.

  7. Investigation of the antioxidant and radical scavenging activities of some phenolic Schiff bases with different free radicals.

    Science.gov (United States)

    Marković, Zoran; Đorović, Jelena; Petrović, Zorica D; Petrović, Vladimir P; Simijonović, Dušica

    2015-11-01

    The antioxidant properties of some phenolic Schiff bases in the presence of different reactive particles such as (•)OH, (•)OOH, (CH2=CH-O-O(•)), and (-•)O2 were investigated. The thermodynamic values, ΔH BDE, ΔH IP, and ΔH PA, were used for this purpose. Three possible mechanisms for transfer of hydrogen atom, concerted proton-electron transfer (CPET), single electron transfer followed by proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET) were considered. These mechanisms were tested in solvents of different polarity. On the basis of the obtained results it was shown that SET-PT antioxidant mechanism can be the dominant mechanism when Schiff bases react with radical cation, while SPLET and CPET are competitive mechanisms for radical scavenging of hydroxy radical in all solvents under investigation. Examined Schiff bases react with the peroxy radicals via SPLET mechanism in polar and nonpolar solvents. The superoxide radical anion reacts with these Schiff bases very slowly.

  8. Photoelectron spectroscopy of higher bromine and iodine oxide anions: electron affinities and electronic structures of BrO(2,3) and IO(2-4) radicals.

    Science.gov (United States)

    Wen, Hui; Hou, Gao-Lei; Huang, Wei; Govind, Niranjan; Wang, Xue-Bin

    2011-11-14

    This report details a photoelectron spectroscopy (PES) and theoretical investigation of electron affinities (EAs) and electronic structures of several atmospherically relevant higher bromine and iodine oxide molecules in the gas phase. PES spectra of BrO(2)(-) and IO(2)(-) were recorded at 12 K and four photon energies--355 nm/3.496 eV, 266 nm/4.661 eV, 193 nm/6.424 eV, and 157 nm/7.867 eV--while BrO(3)(-), IO(3)(-), and IO(4)(-) were only studied at 193 and 157 nm due to their expected high electron binding energies. Spectral features corresponding to transitions from the anionic ground state to the ground and excited states of the neutral are unraveled and resolved for each species. The EAs of these bromine and iodine oxides are experimentally determined for the first time (except for IO(2)) to be 2.515 ± 0.010 (BrO(2)), 2.575 ± 0.010 (IO(2)), 4.60 ± 0.05 (BrO(3)), 4.70 ± 0.05 (IO(3)), and 6.05 ± 0.05 eV (IO(4)). Three low-lying excited states along with their respective excitation energies are obtained for BrO(2) [1.69 (A (2)B(2)), 1.79 (B (2)A(1)), 1.99 eV (C (2)A(2))], BrO(3) [0.7 (A (2)A(2)), 1.6 (B (2)E), 3.1 eV (C (2)E)], and IO(3) [0.60 (A (2)A(2)), 1.20 (B (2)E), ∼3.0 eV (C (2)E)], whereas six excited states of IO(2) are determined along with their respective excitation energies of 1.63 (A (2)B(2)), 1.73 (B (2)A(1)), 1.83 (C (2)A(2)), 4.23 (D (2)A(1)), 4.63 (E (2)B(2)), and 5.23 eV (F (2)B(1)). Periodate (IO(4)(-)) possesses a very high electron binding energy. Only one excited state feature with 0.95 eV excitation energy is shown in the 157 nm spectrum. Accompanying theoretical calculations reveal structural changes from the anions to the neutrals, and the calculated EAs are in good agreement with experimentally determined values. Franck-Condon factors simulations nicely reproduce the observed vibrational progressions for BrO(2) and IO(2). The low-lying excited state information is compared with theoretical calculations and discussed with their

  9. ROLE OF COPPER,ZINC-SUPEROXIDE DISMUTASE IN CATALYZING NITROTYROSINE FORMATION IN MURINE LIVER

    Science.gov (United States)

    The solely known function of Cu,Zn-superoxide dismutase (SOD1) is to catalyze the dismutation of superoxide anion into hydrogen peroxide. Our objective was to determine if SOD1 catalyzed murine liver protein nitration induced by acetaminophen (APAP) and lipopolysaccharide (LPS). Liver and plasma ...

  10. A new formula to calculate activity of superoxide dismutase in indirect assays

    NARCIS (Netherlands)

    Zhang, Chen; Bruins, Marieke E.; Yang, Zhi Qiang; Liu, Shu Tao; Rao, Ping Fan

    2016-01-01

    To calculate superoxide dismutase (SOD) activity rapidly and accurately by indirect SOD assays, a formula based on the ratio of the catalytic speed of SOD to the reaction speed of the indicator with superoxide anion was deduced. The accuracy of this formula was compared with the conventional form

  11. Cyclization by intramolecular carbolithiation of alkyl- and vinyllithiums prepared by the action of aromatic radical anions on phenyl thioethers. High stereoselectivity in the cyclization accelerated by an allylic lithium oxyanion.

    Science.gov (United States)

    Deng, Kai; Bensari-Bouguerra, Ahlem; Whetstone, Joseph; Cohen, Theodore

    2006-03-17

    The reductive lithiation of alkyl and vinyl phenyl thioethers by aromatic radical anions is shown to be the most general method yet known for preparing organolithiums capable of intramolecular carbometalation of unactivated alkenes to produce five-membered rings and in one case a four-membered ring (in a far higher yield than known cases). The relative rates of cyclization for alkyllithiums are secondary > tertiary > primary, and the yields are very high. In the secondary case, the stereoselectivity is extremely high, producing a cyclopentylmethyllithium with a trans-2-alkyl substituent. A remarkable finding is that for all of the organolithiums a lithium oxyanionic group in the proximal allylic position to the alkene greatly accelerates the cyclization and leads almost exclusively to a trans relationship between the CH(2)Li group and the OLi group, the opposite relationship from that observed in intramolecular carbolithiations by allyllithiums. A mechanistic rationale for this divergence is discussed. One of the two types of proximal homoallylic lithium oxyanions exerts an analogous effect. An intriguing limitation, even occurring with the highly reactive secondary organolithium and in the presence of an allylic oxyanionic group, is the failure of intramolecular carbolithiation when a methyl group is at the terminus of the alkene.

  12. Anion photoelectron imaging spectroscopy of glyoxal

    Science.gov (United States)

    Xue, Tian; Dixon, Andrew R.; Sanov, Andrei

    2016-09-01

    We report a photoelectron imaging study of the radical-anion of glyoxal. The 532 nm photoelectron spectrum provides the first direct spectroscopic determination of the adiabatic electron affinity of glyoxal, EA = 1.10 ± 0.02 eV. This assignment is supported by a Franck-Condon simulation of the experimental spectrum that successfully reproduces the observed spectral features. The vertical detachment energy of the radical-anion is determined as VDE = 1.30 ± 0.04 eV. The reported EA and VDE values are attributed to the most stable (C2h symmetry) isomers of the neutral and the anion.

  13. 螺旋藻体外清除自由基的ESR研究%Investigation with ESR on the Radical Scavenging Effect of Spirulina in Vitro

    Institute of Scientific and Technical Information of China (English)

    赵淑锐; 郑美青; 吴英婷; 薛冰

    2015-01-01

    利用DPPH、Fenton反应、SNAP、黄嘌呤氧化酶氧化黄嘌呤反应产生活性有机氮自由基、羟自由基(·OH)、一氧化氮(NO)自由基、超氧阴离子(·O2-)自由基,以电子顺磁共振法(ESR)研究了螺旋藻体外清除上述四种自由基的作用.该方法操作简单易行,结果直观.结果表明螺旋藻能有效清除上述4种自由基,而且随浓度的增加抗氧化能力也增加,浓度在40 mg/mL时对超氧阴离子和有机氮自由基的清除率达到了90%以上.%Organic nitrogen radicals, hydroxyl radicals (·OH), nitric oxide (NO) radicals, superoxide anion radicals (·O2-) were produced by DPPH, Fenton reaction, SNAP, oxidation reaction of xanthine and xanthine oxidase. The antioxidant activities of spirulina in different concentrations were determined by the four radicals scavenging activity using electron paramagnetic resonance (ESR)Technology. The method was simple and easy to observe the results. Experimental results showed that spirulina have strong free radical scavenging capacity. The free radical scavenging capacity was increased by increasing concentrations. when the concentration in 40 mg/mL , the scavenging rates of Superoxide anion and organic nitrogen radicals reached more than 90%.

  14. Free Radicals and Extrinsic Skin Aging

    Directory of Open Access Journals (Sweden)

    Borut Poljšak

    2012-01-01

    Full Text Available Human skin is constantly directly exposed to the air, solar radiation, environmental pollutants, or other mechanical and chemical insults, which are capable of inducing the generation of free radicals as well as reactive oxygen species (ROS of our own metabolism. Extrinsic skin damage develops due to several factors: ionizing radiation, severe physical and psychological stress, alcohol intake, poor nutrition, overeating, environmental pollution, and exposure to UV radiation (UVR. It is estimated that among all these environmental factors, UVR contributes up to 80%. UV-induced generation of ROS in the skin develops oxidative stress, when their formation exceeds the antioxidant defence ability of the target cell. The primary mechanism by which UVR initiates molecular responses in human skin is via photochemical generation of ROS mainly formation of superoxide anion (O2−•, hydrogen peroxide (H2O2, hydroxyl radical (OH•, and singlet oxygen (1O2. The only protection of our skin is in its endogenous protection (melanin and enzymatic antioxidants and antioxidants we consume from the food (vitamin A, C, E, etc.. The most important strategy to reduce the risk of sun UVR damage is to avoid the sun exposure and the use of sunscreens. The next step is the use of exogenous antioxidants orally or by topical application and interventions in preventing oxidative stress and in enhanced DNA repair.

  15. Extracellular superoxide dismutase of boar seminal plasma.

    Science.gov (United States)

    Kowalowka, M; Wysocki, P; Fraser, L; Strzezek, J

    2008-08-01

    Superoxide dismutase (SOD) is an enzymatic component of the antioxidant defense system that protects spermatozoa by catalysing the dismutation of superoxide anions to hydrogen peroxide and oxygen. Age and season effects on SOD activity in the seminal plasma were measured in boars at the onset of 8 months through a 35-month period. It was found that age-related changes in SOD activity in the seminal plasma were markedly higher in boars less than 2 years of age. However, it appeared that SOD activity was established at the early sexual maturity age (8-12 months). There were variations in SOD activity throughout the season, being significantly higher in spring and autumn than in summer. A secretory extracellular form of SOD (EC-SOD) was purified to homogeneity (350-fold) from boar seminal plasma, using a three-step purification protocol (affinity chromatography followed by ion exchange and ceramic hydroxyapatite chromatography). The molecular properties and specificity of SOD (molecular mass, isoelectric point, optimum pH, thermostability and susceptibility to inhibitors) confirmed that the purified enzyme is an extracellular form of Cu/Zn-superoxide dismutase occurring in boar seminal plasma. The results of this study indicate that EC-SOD is an important antioxidant enzyme of boar seminal plasma, which plays an important physiological role in counteracting oxidative stress in spermatozoa.

  16. The Negative Ion Photoelectron Spectrum of Cyclopropane-1,2,3-Trione Radical Anion, (CO) 3 •– — A Joint Experimental and Computational Study

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Bo; Hrovat, David A.; West, Robert; Deng, Shihu H. M.; Wang, Xue-Bin; Borden, Weston Thatcher

    2014-09-03

    Negative Ion Photoelectron (NIPE) spectra of the radical anion of cyclopropane-1,2,3-trione, (CO)3•-, have been obtained at 20 K, using both 355 and 266 nm lasers for electron photodetachment. The spectra show broadened bands, due to the short lifetimes of both the singlet and triplet states of (CO)3. The smaller intensity of the band with the lower electron binding energy suggests that the singlet is the ground state of (CO)3. From the NIPE spectra, the electron affinity (EA) and the singlet-triplet energy gap of (CO)3 are estimated to be, respectively, EA = 3.1 ± 0.1 eV and ΔEST = -14 ± 3 kcal/mol. High-level, (U)CCSD(T)/aug-cc-pVQZ//(U)CCSD(T)/aug-cc-pVTZ, calcu-lations give EA = 3.04 eV for the 1A1´ ground state of (CO)3 and ΔEST = -13.8 kcal/mol for the energy gap between the 1A1´ and 3A2 states, in excellent agreement with values from the NIPE spectra. In addition, simulations of the vibrational structures for formation of these states of (CO)3 from the 2A2'' state of (CO)3•- provide a good fit to the shapes of broad bands in the 266 nm NIPE spectrum. The NIPE spectrum of (CO)3•- and the analysis of the spectrum by high-quality electronic structure calculations demonstrate that NIPES can not only access and provide information about transition structures, but NIPES can also access and provide information about hilltops on potential energy surfaces.

  17. Cranberry flavonoids prevent toxic rat liver mitochondrial damage in vivo and scavenge free radicals in vitro.

    Science.gov (United States)

    Lapshina, Elena A; Zamaraeva, Maria; Cheshchevik, Vitali T; Olchowik-Grabarek, Ewa; Sekowski, Szymon; Zukowska, Izabela; Golovach, Nina G; Burd, Vasili N; Zavodnik, Ilya B

    2015-06-01

    The present study was undertaken for further elucidation of the mechanisms of flavonoid biological activity, focusing on the antioxidative and protective effects of cranberry flavonoids in free radical-generating systems and those on mitochondrial ultrastructure during carbon tetrachloride-induced rat intoxication. Treatment of rats with cranberry flavonoids (7 mg/kg) during chronic carbon tetrachloride-induced intoxication led to prevention of mitochondrial damage, including fragmentation, rupture and local loss of the outer mitochondrial membrane. In radical-generating systems, cranberry flavonoids effectively scavenged nitric oxide (IC50  = 4.4 ± 0.4 µg/ml), superoxide anion radicals (IC50  = 2.8 ± 0.3 µg/ml) and hydroxyl radicals (IC50  = 53 ± 4 µg/ml). The IC50 for reduction of 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH) was 2.2 ± 0.3 µg/ml. Flavonoids prevented to some extent lipid peroxidation in liposomal membranes and glutathione oxidation in erythrocytes treated with UV irradiation or organic hydroperoxides as well as decreased the rigidity of the outer leaflet of the liposomal membranes. The hepatoprotective potential of cranberry flavonoids could be due to specific prevention of rat liver mitochondrial damage. The mitochondria-addressed effects of flavonoids might be related both to radical-scavenging properties and modulation of various mitochondrial events.

  18. Superoxide reduction by a superoxide reductase lacking the highly conserved lysine residue.

    Science.gov (United States)

    Pinto, Ana F; Romão, Célia V; Pinto, Liliana C; Huber, Harald; Saraiva, Lígia M; Todorovic, Smilja; Cabelli, Diane; Teixeira, Miguel

    2015-01-01

    Superoxide reductases (SORs) are the most recently identified superoxide detoxification systems, being found in microorganisms from the three domains of life. These enzymes are characterized by a catalytic mononuclear iron site, with one cysteine and four histidine ligands of the ferrous active form. A lysine residue in the -EKHVP- motif, located close to the active site, has been considered to be essential for the enzyme function, by contributing to the positive surface patch that attracts the superoxide anion and by controlling the chemistry of the catalytic mechanism through a hydrogen bond network. However, we show here that this residue is substituted by non-equivalent amino acids in several putative SORs from Archaea and unicellular Eukarya. In this work, we focus on mechanistic and spectroscopic studies of one of these less common enzymes, the SOR from the hyperthermophilic Crenarchaeon Ignicoccus hospitalis. We employ pulse radiolysis fast kinetics and spectroscopic approaches to study the wild-type enzyme (-E23T24HVP-), and two mutants, T24K and E23A, the later mimicking enzymes lacking both the lysine and glutamate (a ferric ion ligand) of the motif. The efficiency of the wild-type protein and mutants in reducing superoxide is comparable to other SORs, revealing the robustness of these enzymes to single mutations.

  19. Free radical release and HSP70 expression in two human immune-relevant cell lines after exposure to 1800 MHz radiofrequency radiation.

    Science.gov (United States)

    Lantow, M; Schuderer, J; Hartwig, C; Simkó, M

    2006-01-01

    The goal of this study was to investigate whether radiofrequency (RF) electromagnetic-field (EMF) exposure at 1800 MHz causes production of free radicals and/or expression of heat-shock proteins (HSP70) in human immune-relevant cell systems. Human Mono Mac 6 and K562 cells were used to examine free radical release after exposure to incubator control, sham, RF EMFs, PMA, LPS, heat (40 degrees C) or co-exposure conditions. Several signals were used: continuous-wave, several typical modulations of the Global System for Mobile Communications (GSM): GSM-non DTX (speaking only), GSM-DTX (hearing only), GSM-Talk (34% speaking and 66% hearing) at specific absorption rates (SARs) of 0.5, 1.0, 1.5 and 2.0 W/kg. Heat and PMA treatment induced a significant increase in superoxide radical anions and in ROS production in the Mono Mac 6 cells when compared to sham and/or incubator conditions. No significant differences in free radical production were detected after RF EMF exposure or in the respective controls, and no additional effects on superoxide radical anion production were detected after co-exposure to RF EMFs+PMA or RF EMFs+LPS. The GSM-DTX signal at 2 W/kg produced a significant difference in free radical production when the data were compared to sham because of the decreasing sham value. This difference disappeared when data were compared to the incubator controls. To determine the involvement of heat-shock proteins as a possible inhibitor of free radical production, we investigated the HSP70 expression level after different RF EMF exposures; no significant effects were detected.

  20. Superoxide dismutase phenotypes in duodenal ulcers: A genetic marker?

    Directory of Open Access Journals (Sweden)

    Sulekha S

    2006-01-01

    Full Text Available Background:Cu-Zn superoxide dismutases are antioxidative defensive enzymes that catalyze the reduction of superoxide anions to hydrogen peroxide. Aim:The study focuses on the association of electromorph of superoxide dismutase with duodenal ulcers, which result due to an imbalance between aggressive and defensive factors. Materials and Methods:Endoscopically confirmed 210 duodenal ulcer patients and 185 healthy individuals for comparative analysis were considered for the present study. Phenotyping of superoxide dismutase was carried out by subjecting the RBC membranes to polyacrylamide gel electrophoresis, using appropriate staining protocols. Results:Statistical analysis of SOD phenotypes revealed a significant increase of SOD AFNx012 allele and Superoxide dismutases (SOD 2-2 phenotype in duodenal ulcer group. Among these individuals, a predominance of Helicobacter pylori infection was observed. The increased preponderance of homozygotes can be explained on the basis of reduced and altered enzyme activity, which may lead to disturbance in homeostasis of antioxidant/oxidant culminating in high lipid peroxidative gastric mucosal tissue damage and ulceration. No variation in the distribution of SOD phenotypes with respect to Helicobacter pylori indicates the role of Mn-SOD rather than Cu-Zn SOD in the Helicobacter pylori infected cases as reported earlier. Conclusions:Superoxide dismutase as a genetic marker / gene modifier, encoding for an antioxidant enzyme in maintaining tissue homeostasis of the gastric mucosa is discussed.

  1. BENZO[a]PYRENE METABOLITES EXAGGERATE DNA OXIDATIVE DAMAGE UPON THE INVOLVEMENT OF FREE RADICALS%苯并[a]比代谢产物在自由基参与下加速DNA的氧化损伤

    Institute of Scientific and Technical Information of China (English)

    罗云敬; GAO Da-yuan; WEI Hua-chen

    2003-01-01

    @@ Polycyclic aromatic hydrocarbons (PAHs),which constitute a major class of environmental pollu tants are posing a threat to human health. Benzopyrene,an index of PAH levels omnipresent in the everyday environment ,becomes toxic only when being metabolically and/or photo-activated,i. e. ,in the pres ence of UV light. Free radicals such as superoxide anions ('O2),hydrogen peroxide (H2O2),hydroxyl radicals ('OH) and singlet oxygen (1O2) are involved in carcinogenesis. Wei CE etc[1] studied the effects of different scavengers of active oxygen species (superoxide dismutase,catalase,mannitol and dimethyfu ran) on promoting B[a]P mutagenicity. Bryla P ete[2] investigated the roles of several ROS scavengers in the oxidation and binding of B[a]P to calf thymus DNA using the 32p-postlabeling assay.

  2. Visible Light Sensitized Production of Hydroxyl Radicals Using Fullerol as an Electron-Transfer Mediator.

    Science.gov (United States)

    Lim, Jonghun; Kim, Hyejin; Alvarez, Pedro J J; Lee, Jaesang; Choi, Wonyong

    2016-10-04

    Fullerenes and their derivatives are known to photosensitize the production of singlet oxygen ((1)O2), but their role in generating hydroxyl radical ((•)OH) under visible light has not been reported. Here, we demonstrate that fullerol can mediate the electron transfer from Rhodamine B dye to O2 under visible light irradiation, achieving simultaneous dye decolorization and (•)OH-induced degradation of 4-chlorophenol. The hydroxyl radical is proposed to be produced via a consecutive reduction of molecular oxygen by fullerol anion radical, which is formed through the electron transfer from the dye to the triplet state of fullerol. Mechanistic investigations using various probe reagents such as superoxide dismutase (superoxide quencher), t-butanol ((•)OH quencher), and coumarin ((•)OH probe) provided indirect evidence for the generation of (•)OH under visible light. Furthermore, spin trapping technique directly detected the oxidizing species such as (•)OH, HO2(•), and (1)O2 in the visible light irradiated solution of RhB/fullerol mixture. It was proposed that the photochemical oxidation mechanism depends on pH: (•)OH production is favored at acidic pH through fullerol-mediated sequential electron transfer while (1)O2 is generated as a main oxidant at neutral and alkaline condition through the energy-transfer process. Therefore, the photochemical oxidation can be switchable between (•)OH-driven and (1)O2-driven mechanism by a simple pH adjustment.

  3. Determination of antioxidant and radical scavenging activity of Basil (Ocimum basilicum L. Family Lamiaceae) assayed by different methodologies.

    Science.gov (United States)

    Gülçin, Ilhami; Elmastaş, Mahfuz; Aboul-Enein, Hassan Y

    2007-04-01

    The antioxidant properties of plants have been investigated, in the light of recent scientific developments, throughout the world due to their potent pharmacological activities and food viability. Basil (Ocimum basilicum L. Family Lamiaceae) is used as a kitchen herb and as an ornamental plant in house gardens. In the present study, the possible radical scavenging and antioxidant activity of the water (WEB) and ethanol extracts (EEB) of basil was investigated using different antioxidant methodologies: 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging, scavenging of superoxide anion radical-generated non-enzymatic system, ferric thiocyanate method, reducing power, hydrogen peroxide scavenging and metal chelating activities. Experiments revealed that WEB and EEB have an antioxidant effects which are concentration-dependent. The total antioxidant activity was performed according to the ferric thiocyanate method. At the 50 microg/mL concentration, the inhibition effects of WEB and EEB on peroxidation of linoleic acid emulsion were found to be 94.8% and 97.5%, respectively. On the other hand, the percentage inhibition of a 50 microg/mL concentration of BHA, BHT and alpha-tocopherol was found to be 97.1%, 98.5% and 70.4% inhibition of peroxidation of linoleic acid emulsion, respectively. In addition, WEB and EEB had effective DPPH radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, reducing power and metal chelating activities. Additionally, these various antioxidant activities were compared with BHA, BHT and alpha-tocopherol as reference antioxidants. The additional total phenolic content of these basil extracts was determined as the gallic acid equivalent and were found to be equivalent.

  4. Isolation and assessment of the molecular and electronic structures of azo-anion-radical complexes of chromium and molybdenum. Experimental and theoretical characterization of complete electron-transfer series.

    Science.gov (United States)

    Joy, Sucheta; Krämer, Tobias; Paul, Nanda D; Banerjee, Priyabrata; McGrady, John E; Goswami, Sreebrata

    2011-10-17

    The reaction of 3 equiv of the ligand 2-[(2-chlorophenyl)azo]pyridine (L(a)) or 2-[(4-chlorophenyl)azo]pyridine (L(b)) with 1 equiv of Cr(CO)(6) or Mo(CO)(6) in boiling n-octane afforded [Cr(L(a/b))(3)](0) (1a and 1b) and [Mo(L(a/b))(3)](0) (2a and 2b). The chemical oxidation reaction of these neutral complexes with I(2) in CH(2)Cl(2) provided access to air-stable one-electron-oxidized species as their triiodide (I(3)(-)) salts. The electronic structures of chromium and molybdenum centers coordinated by the three redox noninnocent ligands L(a/b) along with their redox partners have been elucidated by using a host of physical methods: X-ray crystallography, magnetic susceptibility measurements, nuclear magnetic resonance, cyclic voltammetry, absorption spectroscopy, electron paramagnetic resonance spectroscopy, and density functional theory. The four representative complexes, 1a, [1a]I(3), 2a, and [2a]I(3), have been characterized by X-ray crystallography. The results indicate a predominant azo-anion-radical description of the ligands in the neutral chromium(III) species, [Cr(III)(L(•-))(3)], affording a singlet ground state through strong metal-ligand antiferromagnetic coupling. All of the electrochemical processes are ligand-based; i.e., the half-filled (t(2g))(3) set of the Cr(III) d(3) ion remains unchanged throughout. The description of the molybdenum analogue is less clear-cut because mixing between metal- and ligand-based orbitals is more significant. On the basis of variations in net spin densities and orbital compositions, we argue that the oxidation events are again primarily ligand-based, although the electron density at the molybdenum center is clearly more variable than that at the chromium center in the corresponding series [1a](+), 1a, and [1a](-).

  5. Production of superoxide in chloroplast thylakoid membranes ESR study with cyclic hydroxylamines of different lipophilicity.

    Science.gov (United States)

    Kozuleva, Marina; Klenina, Irina; Proskuryakov, Ivan; Kirilyuk, Igor; Ivanov, Boris

    2011-04-06

    Accumulation of nitroxide radicals, DCP· or TMT·, under illumination of a thylakoid suspension containing either hydrophilic, DCP-H, or lipophilic, TMT-H, cyclic hydroxylamines that have high rate constants of the reaction with superoxide radicals, was measured using ESR. A slower accumulation of TMT· in contrast with DCP· accumulation was explained by re-reduction of TMT· by the carriers of the photosynthetic electron transport chain within the membrane. Superoxide dismutase suppressed TMT· accumulation to a lesser extent than DCP· accumulation. The data are interpreted as evidencing the production of intramembrane superoxide in thylakoids.

  6. Electrical and magnetic properties of new compounds of the conductor anion [Ni(dmit2]- and nitronyl nitroxide magnetic radicals Propriedades elétricas e magnéticas de novos compostos com o ânion condutor [Ni(dmit2]- e radicais magnéticos nitronil nitróxido

    Directory of Open Access Journals (Sweden)

    Mauro Cesar Dias

    2007-08-01

    Full Text Available Three compounds have been synthesized with formulae [3-MeRad][Ni(dmit2] (1, [4-MeRad][Ni(dmit2] (2 and [4-PrRad][Ni(dmit2] (3 where [Ni(dmit2]- is an anionic pi-radical (dmit = 1,3-dithiol-2-thione-4,5-dithiolate and [3-MeRad]+ is 3-N-methylpyridinium alpha-nitronyl nitroxide, [4-MeRad]+ is 4-N-methylpyridinium alpha-nitronyl nitroxide and [4-PrRad]+ is 4-N-propylpyridinium alpha-nitronyl nitroxide. The temperature-dependent magnetic susceptibility of 1 revealed that an antiferromagnetic interaction operates between the 3-MeRad+ radical cations with exchange coupling constants of J1 = - 1.72 cm-1 and antiferromagnetism assigned to the spin ladder chains of the Ni(dmit2 radical anions. Compound 1 exhibits semiconducting behavior and 3 presents capacitor behavior in the temperature range studied (4 - 300 K.

  7. To what end does nature produce superoxide? NADPH oxidase as an autocrine modifier of membrane phospholipids generating paracrine lipid messengers.

    Science.gov (United States)

    Saran, Manfred

    2003-10-01

    Production of superoxide anion O2*- by the membrane-bound enzyme NADPH oxidase of phagocytes is a long-known phenomenon; it is generally assumed that O2*-helps phagocytes kill bacterial intruders. The details and the chemistry of the killing process have, however, remained a mystery. Isoforms of NADPH oxidase exist in membranes of nearly every cell, suggesting that reactive oxygen species (ROS) participate in intra- and intercellular signaling processes. What the nature of the signal is exactly, how it is transmitted, and what structural characteristics a receptor of a "radical message" must have, have not been addressed convincingly. This review discusses how the action of messengers is in agreement with radical-specific behavior. In search for the smallest common denominator of cellular free radical activity we hypothesize that O2*- and its conjugate acid, HO2*, may have evolved under primordial conditions as regulators of membrane mechanics and that isoprostanes, widely used markers of "oxidative stress", may be an adventitious correlate of this biologic activity of O2*-/HO2*. An overall picture is presented that suggests that O2*-/HO2* radicals, by modifying cell membranes, help other agents gain access to the hydrophobic region of phospholipid bilayers and hence contribute to lipid-dependent signaling cascades. With this, O2*-/HO2* are proposed as indispensable adjuvants for the generation of cellular signals, for membrane transport, channel gating and hence, in a global sense, for cell viability and growth. We also suggest that many of the allegedly O2*- dependent bacterial pathologies and carcinogenic derailments are due to membrane-modifying activity rather than other chemical reactions of O2*-/HO2*. A consequence of this picture is the potential evolution of the "radical theory of ageing" to a "lipid theory of aging".

  8. Antioxidant activity of Cat's whiskers flavonoid on some reactive oxygen and nitrogen species generating inflammatory cells is mediated by scavenging of free radicals

    Institute of Scientific and Technical Information of China (English)

    Asis Bala; Biswakanth Kar; Indrajit Karmakar; R.B.Suresh Kumar; Pallab Kanti Haldar

    2012-01-01

    AIM:To find out the effect of Cat's whiskers (Cleome gynandra L.,Capparidaceae) flavonoid (CWF) for the scavenging of free radicals in some inflammatory cells.METHODS:Mouse erythrocyte's hemoglobin,peritoneal macrophage,and peripheral blood lymphocytes were oxidized either by some of toxic chemicals (nitrite,carbon tetrachloride) or by enzymatic stimulation (glucoseoxidase) to produce oxidative damage to cells.The protective effect of the CWF was examined,and the biochemical mechanism of action was also investigated in terms of the scavenging of free radicals.RESULTS:CWF (1-20 μg·mL-1) decreased glucoseoxidase and nitrite induce oxidative damage in a concentration dependent manner in an in vitro model and inhibited the lysis of RBC [(28.64 ±13.03)% and (70.31 ± 1.80)%] when mice were treated with CWF (25 and 50 mg·kg-1).To assess the antioxidant potential of CWF in the lymphocytes and macrophages in living animals,the effect of CWF was measured on the elevated level of superoxide anions production in the cells.CWF scavenged the superoxide anion (O2-) production and inhibited the O2-induced destruction of protein and lipid biomolecules.CONCLUSION:The study has established that the CWF mediates its antioxidant activity in some chronic inflammatory cells via its free radical scavenging activity.

  9. Models of Superoxide Dismutases

    Energy Technology Data Exchange (ETDEWEB)

    Cabelli, Diane E.; Riley, Dennis; Rodriguez, Jorge A.; Valentine, Joan Selverstone; Zhu, Haining

    1998-05-20

    In this review we have focused much of our discussion on the mechanistic details of how the native enzymes function and how mechanistic developments/insights with synthetic small molecule complexes possessing SOD activity have influenced our understanding of the electron transfer processes involved with the natural enzymes. A few overriding themes have emerged. Clearly, the SOD enzymes operate at near diffusion controlled rates and to achieve such catalytic turnover activity, several important physical principles must be operative. Such fast electron transfer processes requires a role for protons; i.e., proton-coupled electron transfer (''H-atom transfer'') solves the dilemma of charge separation developing in the transition state for the electron transfer step. Additionally, outer-sphere electron transfer is likely a most important pathway for manganese and iron dismutases. This situation arises because the ligand exchange rates on these two ions in water never exceed {approx}10{sup +7} s{sup -1}; consequently, 10{sup +9} catalytic rates require more subtle mechanistic insights. In contrast, copper complexes can achieve diffusion controlled (>10{sup +9}) exchange rates in water; thus inner-sphere electron transfer processes are more likely to be operative in the Cu/Zn enzymes. Recent studies have continued to expand our understanding of the mechanism of action of this most important class of redox active enzymes, the superoxide dismutases, which have been critical in the successful adaptation of life on this planet to an oxygen-based metabolism. The design of SOD mimic drugs, synthetic models compounds that incorporate this superoxide dismutase catalytic activity and are capable of functioning in vivo, offers clear potential benefits in the control of diseases, ranging from the control of neurodegenerative conditions, such as Parkinson's or Alzheimer's disease, to cancer.

  10. Cu(II)-vitamin D interaction leads to free radical-mediated cellular DNA damage: a novel putative mechanism for its selective cytotoxic action against malignant cells.

    Science.gov (United States)

    Rizvi, Asim; Chibber, Sandesh; Naseem, Imrana

    2015-03-01

    Vitamin D (vit D) is a known anticancer molecule, and cancer cells are reported to have elevated levels of Cu(II) ions. In this study, we show that interaction of vit D and Cu(II) leads to the formation of hydroxyl free radicals, superoxide anion and hydrogen peroxide, which causes severe oxidative stress, selectively in malignant cells. We show that the production of these reactive oxygen species causes cellular DNA fragmentation which may cause cell death. A novel putative chemical mechanism explaining how vit D causes cell death by DNA damage, selectively in malignant cells, is proposed.

  11. Mechanism of Scavenging Reactive Oxygen Radicals of Tea catechins%茶儿茶素清除活性氧自由基的机制

    Institute of Scientific and Technical Information of China (English)

    陈留记; 杨贤强; 沈生荣; 王岳飞

    2002-01-01

    @@ Tea catechins, have received considerable attention in recent years due to their numerous potentially beneficial medicinal properties. A common discussed mechanism of their biological and pharmacological effects is the antioxidative activities of tea catechins. In this paper, we evaluated the scavenging effects of four catechins both on superoxide anions (O2-) and hydroxyl free radical (@OH). In addition their synergic effects, structure-activity relationship, as well as stoichiometric factors and rate constants for the reactions of O2-and @OH with EGCG were discussed.

  12. Manipulation of persistent free radicals in biochar to activate persulfate for contaminant degradation.

    Science.gov (United States)

    Fang, Guodong; Liu, Cun; Gao, Juan; Dionysiou, Dionysios D; Zhou, Dongmei

    2015-05-01

    This study investigated the effects of metals (Fe3+, Cu2+, Ni2+, and Zn2+) and phenolic compounds (PCs: hydroquinone, catechol, and phenol) loaded on biomass on the formation of persistent free radicals (PFRs) in biochar. It was found that metal and phenolic compound treatments not only increased the concentrations of PFRs in biochar but also changed the types of PFRs formed, which indicated that manipulating the amount of metals and PCs in biomass may be an efficient method to regulate PFRs in biochar. These results provided direct evidence to elucidate the mechanism of PFR formation in biochar. Furthermore, the catalytic ability of biochar toward persulfate activation for the degradation of contaminants was evaluated. The results indicated that biochar activates persulfate to produce sulfate radicals (SO4•-) and degraded polychlorinated biphenyls (PCBs) efficiently. It was found that both the concentration and type of PFRs were the dominant factors controlling the activation of persulfate by biochar and that superoxide radical anions account for 20-30% of sulfate radical generation in biochar/persulfate. This conclusion was supported by linear correlations between the concentration of PFRs consumed and the formation of SO4•- and between λ (λ=[formed sulfate radicals]/[consumed PFRs]) and g-factors. The findings of this study provide new methods to manipulate PFR concentration in biochar for the transformation of contaminants and development of new alternative activators for persulfate-based remediation of contaminated soils.

  13. Extra Copper-mediated Enhancement of the DNA Cleavage Activity Supported with Wild-type Cu, Zn Superoxide Dismutase

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ruo-Yu; JIANG Wei; ZHANG Li-Na; WANG Li; LIU Chang-Lin

    2008-01-01

    It is well known that the primary function of wild type Cu, Zn superoxide dismutase (holo SOD) is to catalyze the conversion of the superoxide anion to H2O2 and O2 as an antioxidant enzyme. However, the aberrant copper-mediated oxidation chemistry in the enzyme (including its mutation forms) that damages nucleic acids, proteins including itself and cell membrane has attracted extensive attention in the past decade. The present study examined the hydrogen peroxide-dependent DNA cleavage activity supported with the combinations between holo SOD and extra copper (holo SOD+nCu(Ⅱ)). The results indicate that the presence of extra copper can enhance the DNA cleavage activity and a cooperative effect between holo SOD and the extra Cu(Ⅱ) occurs in DNA cleavage. The relative activity and kinetic assay showed that the DNA cleavage activity of holo SOD+nCu(Ⅱ) was enhanced upon addition of extra Cu(Ⅱ). The favorable pH regions for the DNA cleavage were observed to be 3.6-5.6 and 9.0-10, suggesting the species responsible for the DNA cleavage are different in different pH regions. In addition,to obtain an insight into DNA cleavage pathways, the effect of free radical scavengers and inhibitors on the DNA cleavage activity was probed.

  14. Cu/Zn-superoxide dismutase from the fungal strain Humicola lutea 103 improves ram spermatozoa functions in vitro.

    Science.gov (United States)

    Stefanov, R; Angelova, M; Stefanova, T; Subev, M; Dolashka, P; Voelter, W; Zachariev, Z

    2004-04-01

    In this study we determined the effect of reactive oxygen species (ROS) generation during incubation in media at 39 degrees C on ram spermatozoa and the protection by exogenously added antioxidant enzyme, superoxide dismutase (SOD). A novel Cu/Zn-SOD, isolated from the fungal strain Humicola lutea 103 (HLSOD), was used. Our results point out that the levels of both, superoxide anion radicals (*O2-) and H2O2, increase approximately 8-10- and 2-3-fold, respectively, during incubation of spermatozoa. Enhanced ROS generation coincided with reduction of motility, independently of the type of diluted medium. Addition of HLSOD (30, 60 and 120 U ml(-1) sperm) improved sperm functions, maintaining almost initial percentages of motile spermatozoa and increasing the values of mean cytochemical coefficient. At the same time, a significant diminution of *O2- and H2O2 content in the presence of antioxidant enzyme was established. The results suggest that HLSOD is an effective *O2- scavenger in semen that leads to protection of sperm functions.

  15. Oxidation of Hantzsch 1,4-dihydropyridines of pharmacological significance by electrogenerated superoxide.

    Science.gov (United States)

    Ortiz, M E; Núñez-Vergara, L J; Camargo, C; Squella, J A

    2004-03-01

    To study the reaction of a series of Hantzsch dihydropyridines with pharmacological significance such as, nifedipine, nitrendipine, nisoldipine, nimodipine, isradipine and felodipine, with electrogenerated superoxide in order to identify products and postulate a mechanism. The final pyridine derivatives were separated and identified by gas chromatography/mass spectrometry (GC-MS). The intermediates, anion dihydropyridine and the HO2*/HO2- species, were observed from voltammetric studies and controlled potential electrolysis was used to electrogenerate O2*-. The current work reveals that electrogenerated superoxide can quantitatively oxidize Hantzsch dihydropyridines to produce the corresponding aromatized pyridine derivatives. Our results indicate that the aromatization of Hantzsch dihydropyridines by superoxide is initiated by proton transfer from the N1-position on the 1,4-dihydropyridine ring to give the corresponding anion dihydropyridine, which readily undergoes further homogeneous oxidations to provide the final aromatized products. The oxidation of the anionic species of the dihydropyridine is more easily oxidized than the parent compound.

  16. Free radical scavenging property and antiproliferative activity of Rhodiola imbricata Edgew extracts in HT-29 human colon cancer cells

    Institute of Scientific and Technical Information of China (English)

    Ravichandran Senthilkumar; Thangaraj Parimelazhagan; Om Prakash Chaurasia; RB Srivastava

    2013-01-01

    Objective: To investigate the in vitro antioxidant and antiproliferative activity of rhizome extracts of Rhodiola imbricata (R. imbricata) in HT-29 human colon cancer cell line. Methods: The successively extracted rhizome of R. imbricata using various solvents was analyzed for their total phenolics, tannins and flavonoid contents. In vitro antioxidant activity was evaluated by employing different assays, including DPPH, ABTS radical scavenging assays, FRAP, phosphomolybdenum reduction assay, superoxide anion, hydroxyl radical scavenging activities and metal chelating ability. Results: Acetone and methanol extracts recorded higher phenolic content and showed comparable antioxidant activity with standard reference. Additionally, they also inhibited the proliferation of HT-29 cells upon treatment at higher concentration (200 μg/mL) (acetone and methanol, 84% and 84%, respectively). On examination acetone extract exhibited antiproliferative activity in a concentration dependent manner whereas, methanol extract showed both dose dependent and time dependent inhibitory activity. Conclusions: The results obtained justify the traditional usage of R. imbricata from their promising antioxidant activity.

  17. Mutations by near-ultraviolet radiation in Escherichia coli strains lacking superoxide dismutase

    Energy Technology Data Exchange (ETDEWEB)

    Hoerter, J. (Stephens College, Columbia (USA). Department of Natural Sciences); Eisenstark, A. (Missouri Univ., Columbia, MO (USA). Div. of Biological Sciences Paris 7 Universite (France). Centre National de la Recherche, Institut Jacques Monod); Touati, D. (Paris 7 Universite (France). Centre National de la Recherche, Institut Jacques Monod)

    1989-12-01

    In wild-type Eschericia coli, near-ultraviolet radiation (NUV) was only weakly mutagenic. However, in an allelic mutant strain (sodA sodB) that lacks both Mn- and Fe-superoxide dismutase (SOD) and assumed to have excess superoxide anion, NUV induced a 9-fold increase in mutatin above the level that normally occurs in this double mutant. When a sodA sodB double mutant contained a plasmid carrying katG{sup +} (excess HP-I catalase), mutation by NUV was reduced to wild-type (sodA{sup +} sodB{sup +}) levels. Also, in the sodA sodB xthA triple mutant, which lacks exonuclease III (exoIII) in addition to SOD, the mutational frequency by NUV was reduced to wild-type levels. This synergistic action of NUV and O{sub 2}{sup {minus}} suggested that pre-mutational lesions occur, with exoIII converting these lesions to stable mutants. Exposure to H{sub 2}O{sub 2} induced a 2.8-fold increase in mutations in sodA sodB double mutants, but was reduced to control levels when a plasmid carrying katG{sup +} was introduced. These results suggest that NUV, in addition to its other effects on cells, increases mutations indirectly by increasing the flux of OH{sup .} radicals, possibly by generating excess H{sub 2}O{sub 2}. (author). 20 refs.; 1 fig.; 1 tab.

  18. Effects of superoxide generating systems on muscle tone, cholinergic and NANC responses in cat airway.

    Science.gov (United States)

    Bauer, V; Nakajima, T; Pucovsky, V; Onoue, H; Ito, Y

    2000-02-14

    To study the possible role of reactive oxygen species in airway hyperreactivity, we examined the effects of the superoxide anion radical (O(2)(-)) generating systems, pyrogallol and xanthine with xanthine oxidase, on muscle tone, excitatory and inhibitory neurotransmission in the cat airway. Smooth muscle contraction or non-adrenergic non-cholinergic (NANC) relaxation evoked by electrical field stimulation (EFS) were measured before or after O(2)(-) generating systems with or without diethydithiocarbamic acid (DEDTCA), an inhibitor of endogenous superoxide dismutase (SOD). Resting membrane potential or excitatory junction potential (EJP) were also measured in vitro. Both pyrogallol and xanthine/xanthine oxidase produced biphasic changes in basal and elevated (by 5-HT) muscle tone. After SOD pretreatment, both systems consistently produced a prolonged contraction, thereby indicating that O(2)(-) was converted to H(2)O(2) by the action of SOD and as a result the actions of O(2)(-) were lost but those of H(2)O(2) introduced. The O(2)(-) showed no significant effect on smooth muscle contraction or EJP evoked by EFS, however after DEDTCA pretreatment, it evoked initial enhancement followed by suppression of the contraction and EJP. DEDTCA pretreatment ameliorated the inhibitory action of pyrogallol and xanthine/xanthine oxidase on the NANC relaxation, probably because O(2)(-) could combine with endogenous NO to form peroxynitrite. These results indicate that the O(2)(-) generating systems have multiple actions, presumably due to the presence and simultaneous action of at least two different reactive oxygen species (O(2)(-) and H(2)O(2)). While H(2)O(2) seems to be responsible for elevation of muscle tone and augmentation of smooth muscle contraction by EFS, O(2)(-) inhibits muscle tone, cholinergic and NANC neurotransmission.

  19. Dark production of extracellular superoxide by the coral Porites astreoides and representative symbionts

    Directory of Open Access Journals (Sweden)

    Tong Zhang

    2016-11-01

    Full Text Available The reactive oxygen species (ROS superoxide has been implicated in both beneficial and detrimental processes in coral biology, ranging from pathogenic disease resistance to coral bleaching. Despite the critical role of ROS in coral health, there is a distinct lack of ROS measurements and thus an incomplete understanding of underpinning ROS sources and production mechanisms within coral systems. Here, we quantified in situ extracellular superoxide concentrations at the surfaces of aquaria-hosted Porites astreoides during a diel cycle. High concentrations of superoxide (~10’s of nM were present at coral surfaces, and these levels did not change significantly as a function of time of day. These results indicate that the coral holobiont produces extracellular superoxide in the dark, independent of photosynthesis. As a short-lived anion at physiological pH, superoxide has a limited ability to cross intact biological membranes. Further, removing surface mucus layers from the P. astreoides colonies did not impact external superoxide concentrations. We therefore attribute external superoxide derived from the coral holobiont under these conditions to the activity of the coral host epithelium, rather than mucus-derived epibionts or internal sources such as endosymbionts (e.g., Symbiodinium. However, endosymbionts likely contribute to internal ROS levels via extracellular superoxide production. Indeed, common coral symbionts, including multiple strains of Symbiodinium (clades A to D and the bacterium Endozoicomonas montiporae LMG 24815, produced extracellular superoxide in the dark and at low light levels. Further, representative P. astreoides symbionts, Symbiodinium CCMP2456 (clade A and E. montiporae, produced similar concentrations of superoxide alone and in combination with each other, in the dark and low light, and regardless of time of day. Overall, these results indicate that healthy, non-stressed P. astreoides and representative symbionts produce

  20. Salicylic acid-induced superoxide generation catalyzed by plant peroxidase in hydrogen peroxide-independent manner.

    Science.gov (United States)

    Kimura, Makoto; Kawano, Tomonori

    2015-01-01

    It has been reported that salicylic acid (SA) induces both immediate spike and long lasting phases of oxidative burst represented by the generation of reactive oxygen species (ROS) such as superoxide anion radical (O2(•-)). In general, in the earlier phase of oxidative burst, apoplastic peroxidase are likely involved and in the late phase of the oxidative burst, NADPH oxidase is likely involved. Key signaling events connecting the 2 phases of oxidative burst are calcium channel activation and protein phosphorylation events. To date, the known earliest signaling event in response to exogenously added SA is the cell wall peroxidase-catalyzed generation of O2(•-) in a hydrogen peroxide (H2O2)-dependent manner. However, this model is incomplete since the source of the initially required H2O2 could not be explained. Based on the recently proposed role for H2O2-independent mechanism for ROS production catalyzed by plant peroxidases (Kimura et al., 2014, Frontiers in Plant Science), we hereby propose a novel model for plant peroxidase-catalyzed oxidative burst fueled by SA.

  1. Structural and molecular basis of the peroxynitrite-mediated nitration and inactivation of Trypanosoma cruzi iron-superoxide dismutases (Fe-SODs) A and B: disparate susceptibilities due to the repair of Tyr35 radical by Cys83 in Fe-SODB through intramolecular electron transfer.

    Science.gov (United States)

    Martinez, Alejandra; Peluffo, Gonzalo; Petruk, Ariel A; Hugo, Martín; Piñeyro, Dolores; Demicheli, Verónica; Moreno, Diego M; Lima, Analía; Batthyány, Carlos; Durán, Rosario; Robello, Carlos; Martí, Marcelo A; Larrieux, Nicole; Buschiazzo, Alejandro; Trujillo, Madia; Radi, Rafael; Piacenza, Lucía

    2014-05-02

    Trypanosoma cruzi, the causative agent of Chagas disease, contains exclusively iron-dependent superoxide dismutases (Fe-SODs) located in different subcellular compartments. Peroxynitrite, a key cytotoxic and oxidizing effector biomolecule, reacted with T. cruzi mitochondrial (Fe-SODA) and cytosolic (Fe-SODB) SODs with second order rate constants of 4.6 ± 0.2 × 10(4) M(-1) s(-1) and 4.3 ± 0.4 × 10(4) M(-1) s(-1) at pH 7.4 and 37 °C, respectively. Both isoforms are dose-dependently nitrated and inactivated by peroxynitrite. Susceptibility of T. cruzi Fe-SODA toward peroxynitrite was similar to that reported previously for Escherichia coli Mn- and Fe-SODs and mammalian Mn-SOD, whereas Fe-SODB was exceptionally resistant to oxidant-mediated inactivation. We report mass spectrometry analysis indicating that peroxynitrite-mediated inactivation of T. cruzi Fe-SODs is due to the site-specific nitration of the critical and universally conserved Tyr(35). Searching for structural differences, the crystal structure of Fe-SODA was solved at 2.2 Å resolution. Structural analysis comparing both Fe-SOD isoforms reveals differences in key cysteines and tryptophan residues. Thiol alkylation of Fe-SODB cysteines made the enzyme more susceptible to peroxynitrite. In particular, Cys(83) mutation (C83S, absent in Fe-SODA) increased the Fe-SODB sensitivity toward peroxynitrite. Molecular dynamics, electron paramagnetic resonance, and immunospin trapping analysis revealed that Cys(83) present in Fe-SODB acts as an electron donor that repairs Tyr(35) radical via intramolecular electron transfer, preventing peroxynitrite-dependent nitration and consequent inactivation of Fe-SODB. Parasites exposed to exogenous or endogenous sources of peroxynitrite resulted in nitration and inactivation of Fe-SODA but not Fe-SODB, suggesting that these enzymes play distinctive biological roles during parasite infection of mammalian cells.

  2. Copper complexes of bioactive ligands with superoxide dismutase activity.

    Science.gov (United States)

    Khalid, Huma; Hanif, Muhammad; Hashmi, Muhammad Ali; Mahmood, Tariq; Ayub, Khurshid; Monim-Ul-Mehboob, Muhammad

    2013-11-01

    Free radicals or reactive oxygen species (ROS) are highly toxic and their damaging effects result in a variety of detrimental health issues such as neurodegenerative, cardiovascular and age-related diseases. Human body has evolved an effective defense system including superoxide dismutase (SOD) and catalase against the toxicity of these free radicals. SOD is a metalloenzyme and it acts as an excellent antioxidant to protect the body from superoxide radicals that are generated in the biological system. However, the clinical use of SOD is limited due to its short in vivo life span, and its large size that hampered its penetration across the cell membranes. Pharmaceuticals that provide ROS scavenging systems are the most effective when the production of ROS exceeds the scavenging capacity of endogenous SOD as a result of aging or pathological processes. Inspired by the Nature, scientists have designed metal-based mimics of the superoxide dismutase. This review focuses on different copper complexes that are developed from bioactive ligands and mimic the protecting action of the SOD.

  3. Alterations of hepatocyte function with free radical generators and reparation or prevention with coffee polyphenols.

    Science.gov (United States)

    Saidi Merzouk, Amel; Hafida, Merzouk; Medjdoub, Amel; Loukidi, Bouchra; Cherrak, Sabri; Merzouk, Sid Ahmed; Elhabiri, Mourad

    2017-03-01

    Liver diseases are linked in the majority of cases to oxidative stress that antioxidants could neutralize with reducing liver injury. Chlorogenic acid, a coffee polyphenol, possesses antioxidant prosperities. The aim of this study was to evaluate in vitro preventive and corrective effects of cholorogenic acid in hepatocyte toxicity induced by free radicals. Hepatocytes were isolated from adult male Wistar rats. To determine corrective effects and reparation, cells were first exposed to two free radical generators (hydrogen peroxide/iron sulfate for hydroxyl radical formation, and phenazine methosulfate/nicotinamide adenine dinucleotide for superoxide anion formation) for 12H and thereafter treated by chlorogenic acid (1 and 10 μM final concentration) for another 12H. To show preventive effects, cells were pretreated by chlorogenic acid and thereafter exposed to free radical generators. Hepatocyte proliferation, glucose uptake, ATP contents, membrane fluidity and integrity, and intracellular redox status were investigated after 24H culture. The results showed that chlorogenic acid reversed the decrease in cell proliferation, glucose uptake and ATP levels, the increased LDH release and the reduced membrane fluidity and restored the oxidant/antioxidant status under oxidative stress. When pre-treated with chlorogenic acid, hepatocytes became very resistant to oxidative conditions and cellular homeostasis was maintained. In conclusion, chlorogenic acid displayed not only corrective but also preventive effects in hepatocytes exposed to oxidative stress and could be beneficial in patients with or at risk of liver diseases.

  4. Free radical scavenging potential and HPTLC analysis of Indigofera tinctoria linn (Fabaceae

    Directory of Open Access Journals (Sweden)

    Sakthivel Srinivasan

    2016-04-01

    Full Text Available The objective of this study was to evaluate the free radical scavenging potential and high performance thin layer chromatography (HPTLC fingerprinting of Indigofera tinctoria (I. tinctoria. Phytochemical analysis was carried out using standard methods, and free radical scavenging activity of the plant was determined using 2,2-diphenyl-1-picrylhydrazy (DPPH, nitric oxide (NO and superoxide anion (O2− radical scavenging capacities. HPTLC plate was kept in CAMAG TLC Scanner 3 and the Rf values at fingerprint data were recorded by WINCATS software. Aqueous extract of I. tinctoria reliably showed the total phenolics (267.2±2.42 mg/g, flavonoids (75.43±3.36 mg/g and antioxidants (349.11±8.04 mg/g. The extract was found to have DPPH (52.08%, NO (23.12% and O2− (26.79% scavenging activities at the concentration of 250 μg/mL and the results were statistically significant compared with ascorbic acid standard (p<0.05. HPTLC results confirmed that the extract contained several potential active components such as phenols, flavonoids, saponins and terpenoids as the slides revealed multi-colored bands of varying intensities. This study confirmed that the plant had multipotential antioxidant and free radicals scavenging activities.

  5. Free radical scavenging potential and HPTLC analysis of Indigofera tinctoria linn (Fabaceae)$

    Institute of Scientific and Technical Information of China (English)

    Sakthivel Srinivasan; Wankupar Wankhar; Sheeladevi Rathinasamy; Ravindran Rajan n

    2016-01-01

    The objective of this study was to evaluate the free radical scavenging potential and high performance thin layer chromatography (HPTLC) fingerprinting of Indigofera tinctoria (I. tinctoria). Phytochemical analysis was carried out using standard methods, and free radical scavenging activity of the plant was determined using 2,2-diphenyl-1-picrylhydrazy (DPPH), nitric oxide (NO) and superoxide anion ( O−2 ) radical scavenging capacities. HPTLC plate was kept in CAMAG TLC Scanner 3 and the Rf values at fin-gerprint data were recorded by WINCATS software. Aqueous extract of I. tinctoria reliably showed the total phenolics (267.2 7 2.42 mg/g), flavonoids (75.43 7 3.36 mg/g) and antioxidants (349.11 7 8.04 mg/g). The extract was found to have DPPH (52.08%), NO (23.12%) and O−2 (26.79%) scavenging activities at the concentration of 250μg/mL and the results were statistically significant compared with ascorbic acid standard (p o 0.05). HPTLC results confirmed that the extract contained several potential active com-ponents such as phenols, flavonoids, saponins and terpenoids as the slides revealed multi-colored bands of varying intensities. This study confirmed that the plant had multipotential antioxidant and free ra-dicals scavenging activities.

  6. Isolation and characterisation of in vitro and cellular free radical scavenging peptides from corn peptide fractions.

    Science.gov (United States)

    Wang, Liying; Ding, Long; Wang, Ying; Zhang, Yan; Liu, Jingbo

    2015-02-16

    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-flight 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.

  7. Catalytic Radical Domino Reactions in Organic Synthesis.

    Science.gov (United States)

    Sebren, Leanne J; Devery, James J; Stephenson, Corey R J

    2014-02-07

    Catalytic radical-based domino reactions represent important advances in synthetic organic chemistry. Their development benefits synthesis by providing atom- and step-economical methods to complex molecules. Intricate combinations of radical, cationic, anionic, oxidative/reductive, and transition metal mechanistic steps result in cyclizations, additions, fragmentations, ring-expansions, and rearrangements. This Perspective summarizes recent developments in the field of catalytic domino processes.

  8. CBLB502, an agonist of Toll-like receptor 5, has antioxidant and scavenging free radicals activities in vitro.

    Science.gov (United States)

    Li, Weiguang; Ge, Changhui; Yang, Liu; Wang, Ruixue; Lu, Yiming; Gao, Yan; Li, Zhihui; Wu, Yonghong; Zheng, Xiaofei; Wang, Zhaoyan; Zhang, Chenggang

    2016-01-01

    The bacterial protein flagellin is the known agonist of Toll-like receptor 5 (TLR5). It has been reported that CBLB502, a novel agonist of TLR5 derived from Salmonella flagellin, could reduce radiation toxicity in mouse and primate models, protect mice from dermatitis and oral mucositis caused by radiation, inhibit acute renal ischemic failure, and inhibit the growth of A549 lung cancer cell. The property of CBLB502 is able to bind to TLR5 and activates NF-κB signaling. In this study, we investigated the antioxidant potential and free radicals scavenging properties of CBLB502 in vitro. Interestingly, we found that CBLB502 has a direct and distinct antioxidant capacity and can efficiently scavenge a variety of free radicals, including superoxide anion, hydroxyl radical, and ABTS cation (ABTS(+)). Through wave scanning and kinetic evaluation of scavenging ABTS(+), we found that the ABTS(+) scavenging process of CBLB502 is relatively slow, and the ABTS(+) scavenging activity of CBLB502 has a consistently kinetics characteristics. In conclusion, our results suggested that CBLB502 has antioxidant and scavenging free radicals activities in vitro. It is implied that CBLB502 might partially promote the beneficial protective effect through its scavenging free radicals.

  9. Depressant effects of ambroxol and erdosteine on cytokine synthesis, granule enzyme release, and free radical production in rat alveolar macrophages activated by lipopolysaccharide.

    Science.gov (United States)

    Jang, Yoon Young; Song, Jin Ho; Shin, Yong Kyoo; Han, Eun Sook; Lee, Chung Soo

    2003-04-01

    The present study examined the effects of ambroxol and erdosteine, bronchial expectorants, on the cytokine synthesis, granule enzyme release, and free radical production in rat alveolar macrophages activated by lipopolysaccharide. Ambroxol and erdosteine significantly decreased the production of tumour necrosis factors-alpha, interleukin-1beta, and interleukin-6 in alveolar macrophages activated by lipopolysaccharide. These drugs significantly reduced the production of superoxide anion, hydrogen peroxide, and nitric oxide and the release of acid phosphatase and lysozyme in lipopolysaccharide-activated macrophages. Ambroxol and erdosteine showed no scavenging effect on superoxide anion and hydrogen peroxide, whereas both drugs effectively decomposed nitric oxide. The results show that ambroxol and erdosteine may inhibit the responses, including cytokine synthesis and free radical production, in rat alveolar macrophages activated by lipopolysaccharide. Unlike the production of reactive oxygen species, the inhibitory effect of ambroxol and erdosteine on the production of nitric oxide in lipopolysaccharide-activated alveolar macrophages may be accomplished by a scavenging action on the species and inhibition of the respiratory burst.

  10. Active Oxygen Radical Scavenging Ability of Water-Soluble β-Alanine C60 Adducts

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Water-soluble β-alanine C60 adducts were synthesized, and the scavenging ability to superoxygen anion radical O2-and hydroxyl radicalOH were studied by autoxidation ofpyrogallol and chemiluminescence, respectively. It was found that β-alanine C60 adducts showed an excellent efficiency in eliminating superoxygen anion radical and hydroxyl radical. The 50% inhibition concentration (IC50) for superoxygen anion radical and hydroxyl radical were 0.15 mg/mL and 0.048 mg/mL, respectively. The difference should be mainly attributed to the different scavenging mechanisms.

  11. Photocatalytic Anion Oxidation and Applications in Organic Synthesis.

    Science.gov (United States)

    Hering, Thea; Meyer, Andreas Uwe; König, Burkhard

    2016-08-19

    Ions and radicals of the same kind differ by one electron only. The oxidation of many stable inorganic anions yields their corresponding highly reactive radicals, and visible light excitable photocatalysts can provide the required oxidation potential for this transformation. Air oxygen serves as the terminal oxidant, or cheap sacrificial oxidants are used, providing a very practical approach for generating reactive inorganic radicals for organic synthesis. We discuss in this perspective several recently reported examples: Nitrate radicals are obtained by one-electron photooxidation of nitrate anions and are very reactive toward organic molecules. The photooxidation of sulfinate salts yields the much more stable sulfone radicals, which smoothly add to double bonds. A two-electron oxidation of chloride anions to electrophilic chlorine species reacting with arenes in aromatic substitutions extends the method beyond radical reactions. The chloride anion oxidation proceeds via photocatalytically generated peracidic acid as the oxidation reagent. Although the number of reported examples of photocatalytically generated inorganic radical intermediates for organic synthesis is still small, future extension of the concept to other inorganic ions as radical precursors is a clear perspective.

  12. Channeling the SmI₂ reactions to the radical path: radicals resisting reduction by SmI₂.

    Science.gov (United States)

    Yella, Ramesh; Hoz, Shmaryahu

    2014-08-01

    Studies on the reaction of 4-(2,2-diphenylvinyl)pyridine with SmI2 revealed that the intermediate radical strongly resists further reduction to the corresponding anion. The resistance of the radical to accepting another electron is traced to its stabilization by the nitrogen lone pair. The literature suggests that oxygen may also play a role similar to that of nitrogen in directing the course of the reaction toward radical rather than to anionic chemistry.

  13. In vitroevaluation of free radical scavenging activity ofCodariocalyx motorius root extract

    Institute of Scientific and Technical Information of China (English)

    Uma Chidambaram; Vanitha Pachamuthu; Suganya Natarajan; Bhakkiyalakshmi Elango; Suriyanarayanan; Kunga Mohan Ramkumar

    2013-01-01

    Objective:To determine the phenolic content inCodariocalyx motorius root extract and to evaluate its antioxidant properties using variousin vitro assay systems.Methods: The antioxidant activity was evaluated based on scavenging of 1,1-diphenyl-2-picrylhydrazyl, hydroxyl radicals, superoxide anions, nitric oxide, hydrogen peroxide, peroxynitrite, reducing power and by inhibition of lipid peroxidation which was estimated in terms of thiobarbituric acid reactive substances.Results: The root extract of theCodariocalyx motorius (C. motorius)exhibited potent total antioxidant activity that increased with increasing amount of extract concentration, which was compared with standard drug such as quercetin, butylated hydroxytoluene, tocopherol at different concentrations. The different concentrations of the extracts showed inhibition on lipid peroxidation. In addition, the extracts had effective reducing power, free radical scavenging, super oxide anion scavenging, nitric oxide scavenging, lipid peroxidation, and total phenolic content depending on concentration. High correlation between total phenolic contents and scavenging potential of different reactive oxygen species (r2=0.831-0.978) indicated the polyphenols as the main antioxidants.Conclusions:Codariocalyx motorius (C. motorius) root possess the highly active antioxidant substance which can be used for the treatment of oxidative stress-related diseases.

  14. Superoxide Induces Neutrophil Extracellular Trap Formation in a TLR-4 and NOX-Dependent Mechanism

    Science.gov (United States)

    Al-Khafaji, Ahmed B; Tohme, Samer; Yazdani, Hamza Obaid; Miller, David; Huang, Hai; Tsung, Allan

    2016-01-01

    Neutrophils constitute the early innate immune response to perceived infectious and sterile threats. Neutrophil extracellular traps (NETs) are a novel mechanism to counter pathogenic invasion and sequelae of ischemia, including cell death and oxidative stress. Superoxide is a radical intermediate of oxygen metabolism produced by parenchymal and nonparenchymal hepatic cells, and is a hallmark of oxidative stress after liver ischemia-reperfusion (I/R). While extracellular superoxide recruits neutrophils to the liver and initiates sterile inflammatory injury, it is unknown whether superoxide induces the formation of NETs. We hypothesize that superoxide induces NET formation through a signaling cascade involving Toll-like receptor 4 (TLR-4) and neutrophil NADPH oxidase (NOX). We treated neutrophils with extracellular superoxide and observed NET DNA release, histone H3 citrullination and increased levels of MPO-DNA complexes occurring in a TLR-4–dependent manner. Inhibition of superoxide generation by allopurinol and inhibition of NOX by diphenyleneiodonium prevented NET formation. When mice were subjected to warm liver I/R, we found significant NET formation associated with liver necrosis and increased serum ALT in TLR-4 WT but not TLR-4 KO mice. To reduce circulating superoxide, we pretreated mice undergoing I/R with allopurinol and N-acetylcysteine, which resulted in decreased NETs and ameliorated liver injury. Our study demonstrates a requirement for TLR-4 and NOX in superoxide-induced NETs, and suggests involvement of superoxide-induced NETs in pathophysiologic settings. PMID:27453505

  15. Placental NAD(P)H oxidase mediated superoxide generation in early pregnancy.

    NARCIS (Netherlands)

    Raijmakers, M.; Burton, G.J.; Jauniaux, E.; Seed, P.T.; Peters, W.H.M.; Steegers, E.A.P.; Poston, L.

    2006-01-01

    Early placental development is characterised by rapid cell differentiation and migration, matrix remodelling and angiogenesis. The enzyme NAD(P)H oxidase is a major source of superoxide anions implicated in signalling pathways regulating these processes in other systems. It is also thought to be

  16. [Generation of superoxides during the interaction of melanins with oxygen].

    Science.gov (United States)

    Lapina, V A; Dontsov, A E; Ostrovskiĭ, M A

    1984-10-01

    The rate of nitroblue tetrazolium (NBT) reduction by dihydroxyphenylalanine-melanin, pheomelanin and retinal pigment epithelium melanosomes under aerobic conditions (pH 7.4) is low both in the dark and upon illumination, but increases drastically in the presence of cetyltrimethylammonium bromide (CTAB). Under these conditions, the light insignificantly stimulates NBT reduction (1.3-fold). The reaction is effectively inhibited by superoxide dismutase. This suggests that superoxide anions (O2-. are formed as intermediate reaction products in the course of NBT reduction by melanins. At alkaline values of pH (greater than or equal to 9.0), the O2-.-dependent reduction of NBT can also take place in the absence of CTAB. In contrast with oxidation of photoreduced riboflavin, the melanin oxidation by O2 cannot induce lipid peroxidation. It is concluded that O2-. generation via melanin oxidation of melanosomes occurs only under non-physiological conditions and can hardly take place in vivo.

  17. Molecular structure, optical and magnetic properties of metal-free phthalocyanine radical anions in crystalline salts (H2Pc˙-)(cryptand[2,2,2][Na(+)])·1.5C6H4Cl2 and (H2Pc˙-)(TOA+)·C6H4Cl2 (TOA+ is tetraoctylammonium cation).

    Science.gov (United States)

    Konarev, Dmitri V; Zorina, Leokadiya V; Khasanov, Salavat S; Litvinov, Aleksey L; Otsuka, Akihiro; Yamochi, Hideki; Saito, Gunzi; Lyubovskaya, Rimma N

    2013-05-21

    Ionic compounds containing radical anions of metal-free phthalocyanine (H2Pc˙(-)): (H2Pc˙(-))(cryptand[2,2,2][Na(+)])·1.5C6H4Cl2 (1) and (H2Pc˙(-))(TOA(+))·C6H4Cl2 (2) have been obtained as single crystals for the first time. Their crystal structures have been determined, and optical and magnetic properties have been investigated. The H2Pc˙(-) radical anions have a slightly bowl-like shape with four pyrrole nitrogen atoms located below the molecular plane, while four phenylene substituents are located above this plane. Changes in the average length of N-C and C-C bonds in H2Pc˙(-) in comparison with those in neutral H2Pc indicate that negative charge is mainly delocalized over the 24-atom phthalocyanine ring rather than the phenylene substituents. The H2Pc˙(-) formation is accompanied by a shift of up to 10 cm(-1) and disappearance of some intense IR-active bands whereas the band of the N-H stretching mode is shifted by 21-27 cm(-1) to larger wavenumbers. New bands attributed to H2Pc˙(-) appear in the NIR spectra of the salts with maxima at 1033 and 1028 nm for 1 and 2, respectively. The formation of H2Pc˙(-) is accompanied by the splitting of the Soret and Q-bands of H2Pc into several bands and their blue-shift up to 32 nm. Narrow EPR signals with g = 2.0033 and linewidth of 0.16-0.24 mT at room temperature in the spectra of the salts were attributed to the H2Pc˙(-) radical anions. According to SQUID measurements they have S = 1/2 spin states with effective magnetic moments of 1.73 (1) and 1.78 (2) μB at 300 K. Magnetic behavior of 1 and 2 follows the Curie-Weiss law with negative Weiss temperatures of -0.9 and -0.5 K, respectively, indicating weak antiferromagnetic interactions of spins. The EPR signal splits into two lines below 120 and 80 K for 1 and 2, respectively and these lines are noticeably broadened below 25 K.

  18. Bacteriocuprein superoxide dismutases in pseudomonads

    Energy Technology Data Exchange (ETDEWEB)

    Steinman, H.M.

    1985-06-01

    Two new instances of the rare bacteriocuprein form of superoxide dismutase have been discovered in Pseudomonas diminuta and P. maltophilia. Each species contains a manganese superoxide dismutase as well. Eight other strains of Pseudomonas and Xanthomonas spp. lacked bacteriocupreins and contained either a manganese or an iron superoxide dismutase. Native molecular weights and isoelectric points were determined for all these bacterial dismutases. A monospecific polyclonal antibody was prepared against the bacteriocuprein from Photobacterium leiognathi; it was not cross-reactive with the bacteriocuprein from either Pseudomonas strain. Bacteriocupreins have previously been identified in only two procaryotes, P. leiognathi and Caulobacter crescentus. The discovery of the Pseudomonas bacteriocupreins reveals a broader distribution, raising the possibility that bacteriocupreins are a continuous line of descent among procryotes and not isolated evolutionary occurrences, as previous data suggested.

  19. Endogenous antioxidant defense induction by melon superoxide dismutase reduces cardiac hypertrophy in spontaneously hypertensive rats.

    Science.gov (United States)

    Carillon, Julie; Rugale, Caroline; Rouanet, Jean-Max; Cristol, Jean-Paul; Lacan, Dominique; Jover, Bernard

    2014-08-01

    We assessed the influence of SODB, a melon superoxide dismutase (SOD), on left ventricular (LV) hypertrophy in SHR. SODB (4 or 40U SOD) was given orally for 4 or 28 days to SHR. For each treatment period, LV weight index (LVWI) and cardiomyocytes size were measured. SOD, glutathione peroxidase (GPx) and catalase expressions, and LV production and presence of superoxide anion were determined. Pro-inflammatory markers were also measured. SODB reduced LVWI and cardiomyocytes size after 4 or 28 days. Cardiac SOD and GPx increased by 30-40% with SODB. The presence but not production of superoxide anion was significantly reduced by SODB. No effect of SODB was detected on inflammatory status in any group. The beneficial effect of SODB on cardiac hypertrophy seems to be related to the stimulation of endogenous antioxidant defense, suggesting that SODB may be of interest as a dietary supplementation during conventional antihypertensive therapy.

  20. Evidence that the reactivity of the martian soil is due to superoxide ions

    Science.gov (United States)

    Yen, A. S.; Kim, S. S.; Hecht, M. H.; Frant, M. S.; Murray, B.

    2000-01-01

    The Viking Landers were unable to detect evidence of life on Mars but, instead, found a chemically reactive soil capable of decomposing organic molecules. This reactivity was attributed to the presence of one or more as-yet-unidentified inorganic superoxides or peroxides in the martian soil. Using electron paramagnetic resonance spectroscopy, we show that superoxide radical ions (O2-) form directly on Mars-analog mineral surfaces exposed to ultraviolet radiation under a simulated martian atmosphere. These oxygen radicals can explain the reactive nature of the soil and the apparent absence of organic material at the martian surface.

  1. Free radicals in the aqueous environment

    Energy Technology Data Exchange (ETDEWEB)

    Wood, A.; Laurence, G. [Adelaide Univ., SA (Australia)

    1996-12-31

    Full text: The chemistry of the degradation of organic herbicides and fungicides in natural systems is important in determining operationally important parameters such as withholding times before planting or consumption. Disappearance rates in the field are frequently many time larger than expected from reactions such as hydrolysis arid photochemical- and radical-initiated reactions are frequently cited as causes of the degradation reactions. Reactions of OH and O{sub 2}{sup -} radicals and secondary radicals derived from these are increasingly postulated as being important in many aqueous environmental reactions. Free radical reactions may contribute to the degradation of organic pesticides and are directly implicated in the use of radical generating systems such as Fenton`s Reagent or hydrogen peroxide in the removal of chlorinated organic chemicals from drinking water. Natural sources of these radicals in aqueous systems are predominantly photochemical reactions or reactions initiated by transition metal ions. Hydrogen peroxide is present in many aqueous environments in relatively high concentrations and we are attempting to establish the presence of superoxide radicals in natural systems. The measurement of stationary state concentrations of free radicals as low as 10{sup -} {sup 15} M is a challenge to analytical and free radical chemists. Long term scavenging studies are difficult and generally non-specific. Current ideas will be reviewed and our approach to the measurement of superoxide in natural systems will be outlined.

  2. Efficacy of golden rain tree against free radicals and H2O2-induced damage to pUC18/calf thymus DNA

    Institute of Scientific and Technical Information of China (English)

    Manish Kumar; Madhu Chandel; Neha Sharma; Subodh Kumar; Satwinderjeet Kaur

    2012-01-01

    Objective: To investigate the antioxidant and genoprotective potential of the methanol extract (METH-KP) along with its hexane fraction (HEX-KP) from the leaves of Koelreuteria paniculata (K. paniculata) Laxm. Methods: The antioxidant potential was checked using metal chelation assay, ABTS, DPPH (2,2-diphenyl-2-picryl-hydrazyl), reducing power and superoxide anion radical scavenging assay, Folin-Ciocalteu reducing capacity (FCR assay), Total flavonoid content (TFC assay) and genoprotective activity against the DNA damage induced by Fenton's reagent using pUC18/calf thymus. Results: Results showed that radical scavenging activities of the both test extract/fraction revealed a concentration-dependent antiradical activity in all the assays. In Metal chelation assay, METH-KP and HEX-KP showed 39.04% and 32.51% of scavenging at highest tested concentrations. The METH-KP exhibited IC50 of 54.54 μg/mL in ABTS, 115 μg/mL in DPPH, 110 μg/mL in reducing power and 135 μg/mL in superoxide anion radical scavenging assay while that HEX-KP was found to be very poor in radical scavenging in all the above assays. The phytochemical analysis showed good amount of phenolic and flavonoid compounds in METH-KP while the HEX-KP fraction lacks phenols. The METH-KP extract and HEX-KP fraction both showed DNA protective effect in Calf thymus/pUC18 DNA protection studies. Conclusions: The activity of METH-KP may be attributed to its polyphenolic constituents which needs further isolation of its active constituents which may lead to the development of novel drugs to combat cancer.

  3. The research on the mechanism of superoxide dismutase remove free radicals play a protective effect in myocardial ischemia reperfusion injury%超氧化物歧化酶清除自由基对心肌缺血再灌注损伤的保护作用及其机制

    Institute of Scientific and Technical Information of China (English)

    马德彰; 余晶; 郗敏; 徐逸; 冯幼平

    2014-01-01

    目的 建立小鼠心脏缺血再灌注损伤模型,分别给予两种超氧化物歧化酶(SOD)类似物进行干预治疗,观察心肌组织缺血再灌注以及缺血再灌注后心脏的功能状态.方法 建立小鼠心脏缺血再灌注模型,分别在灌注前5 min给予小鼠SOD类似物及磷酸盐缓冲液(PBS).通过Evans蓝和氯化三苯基四氮唑(TTC)双染色测定梗死心肌面积,激光多普勒测定心肌缺血再灌注后心肌血流量和心功能变化,观察小鼠缺血再灌注心脏损伤变化.结果 采用小鼠心脏冠状动脉左前降支结扎,成功构建小鼠心肌缺血再灌注损伤模型,模型成功率达96%.采用SOD类似物在缺血再灌注前进行干预,可明显减少小鼠心脏再灌注过程中心功能损伤,其中心肌梗死面积由65%下降至37%,平均动脉血压(MABP)平均变化率由33.3%降低为18.9%,差异均有统计学意义(P<0.05).结论 氧自由基分子是心肌缺血再灌注损伤的关键分子,SOD类似物可以通过清除氧自由基来发挥对心肌缺血再灌注损伤的保护作用.%Objective In this study,we establishment the mouse cardiac ischemia repeffusion model,given two superoxide dismutase (SOD) analogues,in order to observe cardiac functions of myocardial ischemia reperfusion and ischemia reperfusion.Methods Establishment of mouse cardiac ischemia reperfusion model.Mice were given SOD analogues and phosphate buffer (PBS) in 5 min respectively before perfusion.By Evans blue and TTC staining determination of myocardial infarct area,laser Dopplermeasurement and changes of myocardial blood flow perfusion and heart function of myocardial ischemia,ischemia repeffusion injury of heart were observed changes.Results Mouse heart left anterior descending coronary artery ligation in mice with myocardial ischemia repeffusion injury model was constructed successfully,the success rate of the model 96%.Using SOD analogs to intervene before ischemia-reperfusion can obviously

  4. Economical synthesis of potassium superoxide

    Science.gov (United States)

    Bell, A. T.; Sadhukhan, P.

    1979-01-01

    High-frequency discharge in oxygen can be used to prepare superoxides of alkali and alkaline-earth metals. Since no direct-current discharge at the electrodes is present, no sputtering can contaminate the product, hence a high conversion efficiency.

  5. Novel mechanisms for superoxide-scavenging activity of human manganese superoxide dismutase determined by the K68 key acetylation site.

    Science.gov (United States)

    Lu, Jiaqi; Cheng, Kuoyuan; Zhang, Bo; Xu, Huan; Cao, Yuanzhao; Guo, Fei; Feng, Xudong; Xia, Qing

    2015-08-01

    Superoxide is the primary reactive oxygen species generated in the mitochondria. Manganese superoxide dismutase (SOD2) is the major enzymatic superoxide scavenger present in the mitochondrial matrix and one of the most crucial reactive oxygen species-scavenging enzymes in the cell. SOD2 is activated by sirtuin 3 (SIRT3) through NAD(+)-dependent deacetylation. However, the exact acetylation sites of SOD2 are ambiguous and the mechanisms underlying the deacetylation-mediated SOD2 activation largely remain unknown. We are the first to characterize SOD2 mutants of the acetylation sites by investigating the relative enzymatic activity, structures, and electrostatic potential of SOD2 in this study. These SOD2 mutations affected the superoxide-scavenging activity in vitro and in HEK293T cells. The lysine 68 (K68) site is the most important acetylation site contributing to SOD2 activation and plays a role in cell survival after paraquat treatment. The molecular basis underlying the regulation of SOD2 activity by K68 was investigated in detail. Molecular dynamics simulations revealed that K68 mutations induced a conformational shift of residues located in the active center of SOD2 and altered the charge distribution on the SOD2 surface. Thus, the entry of the superoxide anion into the coordinated core of SOD2 was inhibited. Our results provide a novel mechanistic insight, whereby SOD2 acetylation affects the structure and charge distribution of SOD2, its tetramerization, and p53-SOD2 interactions of SOD2 in the mitochondria, which may play a role in nuclear-mitochondrial communication during aging.

  6. ACTIVITY OF SUPEROXIDE DISMUTASE ENZYME IN YEAST SACCHAROMYCES CEREVISIAE

    Directory of Open Access Journals (Sweden)

    Blažena Lavová

    2014-02-01

    Full Text Available Reactive oxygen species (ROS with reactive nitrogen species (RNS are known to play dual role in biological systems, they can be harmful or beneficial to living systems. ROS can be important mediators of damage to cell structures, including proteins, lipids and nucleic acids termed as oxidative stress. The antioxidant enzymes protect the organism against the oxidative damage caused by active oxygen forms. The role of superoxide dismutase (SOD is to accelerate the dismutation of the toxic superoxide radical, produced during oxidative energy processes, to hydrogen peroxide and molecular oxygen. In this study, SOD activity of three yeast strains Saccharomyces cerevisiae was determined. It was found that SOD activity was the highest (23.7 U.mg-1 protein in strain 612 after 28 hours of cultivation. The lowest SOD activity from all tested strains was found after 56 hours of cultivation of strain Gyöng (0.7 U.mg-1 protein.

  7. Part 1: Antiplasmodial, cytotoxic, radical scavenging and antioxidant activities of Thai plants in the family Acanthaceae.

    Science.gov (United States)

    Charoenchai, Panarat; Vajrodaya, Srunya; Somprasong, Winai; Mahidol, Chulabhorn; Ruchirawat, Somsak; Kittakoop, Prasat

    2010-11-01

    Crude extracts (CH(2)Cl(2) and MeOH) of 20 plants in the family Acanthaceae were screened for their antiplasmodial, cytotoxic, antioxidant, and radical scavenging activities. These plants included Asystasia nemorum, Barleria cristata, B. strigosa, Dicliptera burmanni, Eranthemum tetragonum, Hygrophila ringens, Justicia balansae, J. procumbens, Lepidagathis incurva, Peristrophe lanceolaria, Phaulopsis dorsiflora, Ruellia kerrii, Strobilanthes auriculata, S. corrugata, S. cusia, S. dimorphotricha, S. karensium, S. maxwellii, S. pateriformis, and S. brandisii. CH(2)Cl(2) extracts of A. nemorum, S. corrugata, S. cusia, S. maxwellii, S. pateriformis, and S. brandisii, as well as MeOH extracts of J. balansae and J. procumbens, showed antiplasmodial activity with IC(50) values of 10-100 µg/mL. CH(2)Cl(2) extracts of nine plants including D. burmanni, H. ringens, J. balansae, J. procumbens, L. incurva, P. lanceolaria, P. dorsiflora, S. corrugata, and S. maxwellii showed cytotoxic activity with IC(50) values of 3.5-46.0 µg/mL. MeOH extracts (at 100 µg/mL) of R. kerrii and S. auriculata could effectively scavenge DPPH free radicals (82-83% inhibition) and superoxide anion radicals (79% and 88% inhibition). In the ORAC antioxidant assay, MeOH extracts of B. cristata, J. procumbens, R. kerrii, and S. auriculata exhibited activity with ORAC units of 3.1-3.9.

  8. Antioxidant, Antimicrobial, and Free Radical Scavenging Potential of Aerial Parts of Periploca aphylla and Ricinus communis

    Science.gov (United States)

    Iqbal, Jamshed; Zaib, Sumera; Farooq, Umar; Khan, Afsar; Bibi, Irum; Suleman, Saba

    2012-01-01

    Context. Many diseases are associated with oxidative stress caused by free radicals. Objective. The present study evaluated the in vitro antioxidant and antibacterial activities of various extracts of aerial parts of Periploca aphylla and Ricinus communis. Materials and Methods. In vitro antioxidant activities of the plant extract were determined by DPPH and NO scavenging method. Superoxide anion radical activity was measured by the reduction of nitro blue tetrazolium as compared with standard antioxidants. Total phenolic contents and antibacterial activities of these plants were determined by gallic acid equivalent (GAE) and serial tube dilution method, respectively. Results. Plants showed significant radical scavenging activity. The results were expressed as IC50. n-Propyl gallate and 3-t-butyl-4-hydroxyanisole were used as standards for antioxidant assay. All the extracts of both plants showed comparable IC50 to those of standards. Plants extract exhibited high phenolic contents and antibacterial activities were comparable with standard drug, Ciprofloxacin. Discussion and Conclusion. The present study provides evidence that Periploca aphylla and Ricinus communis prove to be potent natural antioxidants and could replace synthetic antioxidants. Plants can also be used against pathogenic bacterial strains. PMID:22919511

  9. Peculiarities of the free radical processes in rat liver mitochondria under toxic hepatitis on the background of alimentary protein deficiency

    Directory of Open Access Journals (Sweden)

    G. P. Kopylchuk

    2016-04-01

    Full Text Available The rate of superoxide anion radical, hydroxyl radical and hydrogen peroxide generation, the level of oxidative modification of mitochondrial proteins in the liver of rats with toxic hepatitis was investigated on the background of alimentary protein deficiency. We did not find significant increases of the intensity of free radical processes in liver mitochondria of rats maintained on the protein-deficient ration. The most significant intensification of free radical processes in liver mitochondria is observed under the conditions of toxic hepatitis, induced on the background of alimentary protein deprivation. Under these conditions the aggravation of all studied forms of reactive oxygen species generation was observed in liver mitochondria. The generation rates were increased as follows: O2 – by 1.7 times, Н2О2 – by 1.5 times, •ОН – practically double on the background of accumulation of oxidized mitochondria-derived proteins. The established changes in thiol groups’ redox status of respiratory chain proteins insoluble in 0.05 M sodium-phosphate buffer (pH 11.5, and changes of their carbonyl derivatives content may be considered as one of the regulatory factors of mitochondrial energy-generating function.

  10. Anion exchange membrane

    Science.gov (United States)

    Verkade, John G; Wadhwa, Kuldeep; Kong, Xueqian; Schmidt-Rohr, Klaus

    2013-05-07

    An anion exchange membrane and fuel cell incorporating the anion exchange membrane are detailed in which proazaphosphatrane and azaphosphatrane cations are covalently bonded to a sulfonated fluoropolymer support along with anionic counterions. A positive charge is dispersed in the aforementioned cations which are buried in the support to reduce the cation-anion interactions and increase the mobility of hydroxide ions, for example, across the membrane. The anion exchange membrane has the ability to operate at high temperatures and in highly alkaline environments with high conductivity and low resistance.

  11. How the location of superoxide generation influences the β-cell response to nitric oxide.

    Science.gov (United States)

    Broniowska, Katarzyna A; Oleson, Bryndon J; McGraw, Jennifer; Naatz, Aaron; Mathews, Clayton E; Corbett, John A

    2015-03-20

    Cytokines impair the function and decrease the viability of insulin-producing β-cells by a pathway that requires the expression of inducible nitric oxide synthase (iNOS) and generation of high levels of nitric oxide. In addition to nitric oxide, excessive formation of reactive oxygen species, such as superoxide and hydrogen peroxide, has been shown to cause β-cell damage. Although the reaction of nitric oxide with superoxide results in the formation of peroxynitrite, we have shown that β-cells do not have the capacity to produce this powerful oxidant in response to cytokines. When β-cells are forced to generate peroxynitrite using nitric oxide donors and superoxide-generating redox cycling agents, superoxide scavenges nitric oxide and prevents the inhibitory and destructive actions of nitric oxide on mitochondrial oxidative metabolism and β-cell viability. In this study, we show that the β-cell response to nitric oxide is regulated by the location of superoxide generation. Nitric oxide freely diffuses through cell membranes, and it reacts with superoxide produced within cells and in the extracellular space, generating peroxynitrite. However, only when it is produced within cells does superoxide attenuate nitric oxide-induced mitochondrial dysfunction, gene expression, and toxicity. These findings suggest that the location of radical generation and the site of radical reactions are key determinants in the functional response of β-cells to reactive oxygen species and reactive nitrogen species. Although nitric oxide is freely diffusible, its biological function can be controlled by the local generation of superoxide, such that when this reaction occurs within β-cells, superoxide protects β-cells by scavenging nitric oxide.

  12. AMPK dysregulation promotes diabetes-related reduction of superoxide and mitochondrial function.

    Science.gov (United States)

    Dugan, Laura L; You, Young-Hyun; Ali, Sameh S; Diamond-Stanic, Maggie; Miyamoto, Satoshi; DeCleves, Anne-Emilie; Andreyev, Aleksander; Quach, Tammy; Ly, San; Shekhtman, Grigory; Nguyen, William; Chepetan, Andre; Le, Thuy P; Wang, Lin; Xu, Ming; Paik, Kacie P; Fogo, Agnes; Viollet, Benoit; Murphy, Anne; Brosius, Frank; Naviaux, Robert K; Sharma, Kumar

    2013-11-01

    Diabetic microvascular complications have been considered to be mediated by a glucose-driven increase in mitochondrial superoxide anion production. Here, we report that superoxide production was reduced in the kidneys of a steptozotocin-induced mouse model of type 1 diabetes, as assessed by in vivo real-time transcutaneous fluorescence, confocal microscopy, and electron paramagnetic resonance analysis. Reduction of mitochondrial biogenesis and phosphorylation of pyruvate dehydrogenase (PDH) were observed in kidneys from diabetic mice. These observations were consistent with an overall reduction of mitochondrial glucose oxidation. Activity of AMPK, the major energy-sensing enzyme, was reduced in kidneys from both diabetic mice and humans. Mitochondrial biogenesis, PDH activity, and mitochondrial complex activity were rescued by treatment with the AMPK activator 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR). AICAR treatment induced superoxide production and was linked with glomerular matrix and albuminuria reduction in the diabetic kidney. Furthermore, diabetic heterozygous superoxide dismutase 2 (Sod2(+/-)) mice had no evidence of increased renal disease, and Ampka2(-/-) mice had increased albuminuria that was not reduced with AICAR treatment. Reduction of mitochondrial superoxide production with rotenone was sufficient to reduce AMPK phosphorylation in mouse kidneys. Taken together, these results demonstrate that diabetic kidneys have reduced superoxide and mitochondrial biogenesis and activation of AMPK enhances superoxide production and mitochondrial function while reducing disease activity.

  13. Pseudomonas aeruginosa sodA and sodB mutants defective in manganese- and iron-cofactored superoxide dismutase activity demonstrate the importance of the iron-cofactored form in aerobic metabolism.

    OpenAIRE

    1995-01-01

    The consumption of molecular oxygen by Pseudomonas aeruginosa can lead to the production of reduced oxygen species, including superoxide, hydrogen peroxide, and the hydroxyl radical. As a first line of defense against potentially toxic levels of endogenous superoxide, P. aeruginosa possesses an iron- and manganese-cofactored superoxide dismutase (SOD) to limit the damage evoked by this radical. In this study, we have generated mutants which possess an interrupted sodA (encoding manganese SOD)...

  14. Anions in Cometary Comae

    Science.gov (United States)

    Charnley, Steven B.

    2011-01-01

    The presence of negative ions (anions) in cometary comae is known from Giotto mass spectrometry of IP/Halley. The anions 0-, OH-, C-, CH- and CN- have been detected, as well as unidentified anions with masses 22-65 and 85-110 amu (Chaizy et al. 1991). Organic molecular anions are known to have a significant impact on the charge balance of interstellar clouds and circumstellar envelopes and have been shown to act as catalysts for the gas-phase synthesis of larger hydrocarbon molecules in the ISM, but their importance in cometary comae has not yet been explored. We present details of the first attempt to model the chemistry of anions in cometary comae. Based on the combined chemical and hydro dynamical model of Rodgers & Charnley (2002), we investigate the role of large carbon-chain anions in cometary coma chemistry. We calculate the effects of these anions on coma thermodynamics, charge balance and examine their impact on molecule formation.

  15. Effect of Bothrops alternatus snake venom on macrophage phagocytosis and superoxide production: participation of protein kinase C

    Directory of Open Access Journals (Sweden)

    SS Setubal

    2011-01-01

    Full Text Available Envenomations caused by different species of Bothrops snakes result in severe local tissue damage, hemorrhage, pain, myonecrosis, and inflammation with a significant leukocyte accumulation at the bite site. However, the activation state of leukocytes is still unclear. According to clinical cases and experimental work, the local effects observed in envenenomation by Bothrops alternatus are mainly the appearance of edema, hemorrhage, and necrosis. In this study we investigated the ability of Bothrops alternatus crude venom to induce macrophage activation. At 6 to 100 ¼g/mL, BaV is not toxic to thioglycollate-elicited macrophages; at 3 and 6 ¼g/mL, it did not interfere in macrophage adhesion or detachment. Moreover, at concentrations of 1.5, 3, and 6 ¼g/mL the venom induced an increase in phagocytosis via complement receptor one hour after incubation. Pharmacological treatment of thioglycollate-elicited macrophages with staurosporine, a protein kinase (PKC inhibitor, abolished phagocytosis, suggesting that PKC may be involved in the increase of serum-opsonized zymosan phagocytosis induced by BaV. Moreover, BaV also induced the production of anion superoxide (O2_ by thioglycollate-elicited macrophages. This BaV stimulated superoxide production was abolished after treating the cells with staurosporine, indicating that PKC is an important signaling pathway for the production of this radical. Based on these results, we suggest that phagocytosis and reactive oxygen species are involved in the pathogenesis of local tissue damage characteristic of Bothrops spp. envenomations.

  16. NOC/oFQ PKC-dependent superoxide generation contributes to hypoxic-ischemic impairment of NMDA cerebrovasodilation.

    Science.gov (United States)

    Armstead, W M

    2000-12-01

    This study determined whether nociceptin/orphanin FQ (NOC/oFQ) generates superoxide anion (O(2)(-)) in a protein kinase C (PKC)-dependent manner and whether such production contributes to hypoxic-ischemic (H-I) impairment of N-methyl-D-aspartate (NMDA)-induced pial artery dilation in newborn pigs equipped with closed cranial windows. Superoxide dismutase (SOD)-inhibitable nitroblue tetrazolium (NBT) reduction was an index of O(2)(-) generation. Under non-H-I conditions, topical NOC/oFQ (10(-10) M, concentration present in cerebrospinal fluid after I or H-I) increased SOD-inhibitable NBT reduction from 1 +/- 1 to 20 +/- 3 pmol/mm(2). PKC inhibitors staurosporine and chelerythrine (10(-7) M) blunted NBT reduction (1 +/- 1 to 7 +/- 2 pmol/mm(2) for chelerythrine), whereas the NOC/oFQ receptor antagonist [F/G]NOC/oFQ (1-13)-NH(2) (10(-6) M) blocked NBT reduction. [F/G]NOC/oFQ(1-13)-NH(2) and staurosporine also blunted the NBT reduction observed after I or H-I. NMDA (10(-8), 10(-6) M)-induced pial artery dilation was reversed to vasoconstriction after H-I. The NOC/oFQ antagonist staurosporine and free radical scavengers partially prevented this impaired dilation (sham: 9 +/- 1 and 16 +/- 1; H-I: -5 and -10 +/- 1; H-I staurosporine pretreated: 3 +/- 1 and 6 +/- 1%). These data show that NOC/oFQ increased O(2)(-) production in a PKC-dependent manner and contributed to this production after insult and that NOC/oFQ contributed to impaired NMDA-induced pial artery dilation after H-I, suggesting, therefore, that PKC-dependent O(2)(-) generation by NOC/oFQ links NOC/oFQ release to impaired NMDA dilation after H-I.

  17. Copper complexes of 1,10-phenanthroline and related compounds as superoxide dismutase mimetics.

    Science.gov (United States)

    Bijloo, G J; van der Goot, H; Bast, A; Timmerman, H

    1990-11-01

    In a preliminary study we tested CuSO4.5H2O, (Cu(II]2[3,5-diisopropylsalicylate]4.2H2O and a number of copper complexes of substituted 1,10-phenanthrolines for superoxide anion dismutase activity. It appeared that this activity depends on the ligands involved and might be governed by the redox potential of the Cu(I) complex/Cu(II) complex couple. The strong superoxide anion dismutase activity of Cu(II)[DMP]2 complex can be expected considering its high redox potential. Rather surprisingly is the superoxide anion dismutase activity of the Cu(I)[DMP]2 complex since it involves oxidation to Cu(II)[DMP]2 complex. From regression analysis it was established that steric and field effects of the substituents of the investigated phenanthrolines play an important role in SOD activity and therefore it is concluded that complex formation is important for the superoxide dismutase-like activity.

  18. Metabolic stability of superoxide adducts derived from newly developed cyclic nitrone spin traps.

    Science.gov (United States)

    Bézière, Nicolas; Hardy, Micael; Poulhès, Florent; Karoui, Hakim; Tordo, Paul; Ouari, Olivier; Frapart, Yves-Michel; Rockenbauer, Antal; Boucher, Jean-Luc; Mansuy, Daniel; Peyrot, Fabienne

    2014-02-01

    Reactive oxygen species are by-products of aerobic metabolism involved in the onset and evolution of various pathological conditions. Among them, the superoxide radical is of special interest as the origin of several damaging species such as H2O2, hydroxyl radical, or peroxynitrite (ONOO(-)). Spin trapping coupled with ESR is a method of choice to characterize these species in chemical and biological systems and the metabolic stability of the spin adducts derived from reaction of superoxide and hydroxyl radicals with nitrones is the main limit to the in vivo application of the method. Recently, new cyclic nitrones bearing a triphenylphosphonium or permethylated β-cyclodextrin moiety have been synthesized and their spin adducts demonstrated increased stability in buffer. In this article, we studied the stability of the superoxide adducts of four new cyclic nitrones in the presence of liver subcellular fractions and biologically relevant reductants using an original setup combining a stopped-flow device and an ESR spectrometer. The kinetics of disappearance of the spin adducts were analyzed using an appropriate simulation program. Our results highlight the interest of the new spin trapping agents CD-DEPMPO and CD-DIPPMPO for specific detection of superoxide with high stability of the superoxide adducts in the presence of liver microsomes.

  19. Iron, copper, and manganese complexes with in vitro superoxide dismutase and/or catalase activities that keep Saccharomyces cerevisiae cells alive under severe oxidative stress.

    Science.gov (United States)

    Ribeiro, Thales P; Fernandes, Christiane; Melo, Karen V; Ferreira, Sarah S; Lessa, Josane A; Franco, Roberto W A; Schenk, Gerhard; Pereira, Marcos D; Horn, Adolfo

    2015-03-01

    Due to their aerobic lifestyle, eukaryotic organisms have evolved different strategies to overcome oxidative stress. The recruitment of some specific metalloenzymes such as superoxide dismutases (SODs) and catalases (CATs) is of great importance for eliminating harmful reactive oxygen species (hydrogen peroxide and superoxide anion). Using the ligand HPClNOL {1-[bis(pyridin-2-ylmethyl)amino]-3-chloropropan-2-ol}, we have synthesized three coordination compounds containing iron(III), copper(II), and manganese(II) ions, which are also present in the active site of the above-noted metalloenzymes. These compounds were evaluated as SOD and CAT mimetics. The manganese and iron compounds showed both SOD and CAT activities, while copper showed only SOD activity. The copper and manganese in vitro SOD activities are very similar (IC50~0.4 μmol dm(-3)) and about 70-fold higher than those of iron. The manganese compound showed CAT activity higher than that of the iron species. Analyzing their capacity to protect Saccharomyces cerevisiae cells against oxidative stress (H2O2 and the O2(•-) radical), we observed that all compounds act as antioxidants, increasing the resistance of yeast cells mainly due to a reduction of lipid oxidation. Especially for the iron compound, the data indicate complete protection when wild-type cells were exposed to H2O2 or O2(•-) species. Interestingly, these compounds also compensate for both superoxide dismutase and catalase deficiencies; their antioxidant activity is metal ion dependent, in the order iron(III)>copper(II)>manganese(II). The protection mechanism employed by the complexes proved to be independent of the activation of transcription factors (such as Yap1, Hsf1, Msn2/Msn4) and protein synthesis. There is no direct relation between the in vitro and the in vivo antioxidant activities. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Diosgenin inhibits superoxide generation in FMLP-activated mouse neutrophils via multiple pathways.

    Science.gov (United States)

    Lin, Y; Jia, R; Liu, Y; Gao, Y; Zeng, X; Kou, J; Yu, B

    2014-12-01

    Diosgenin possesses anti-inflammatory and anticancer properties. Activated neutrophils produce high concentrations of the superoxide anion which is involved in the pathophysiology of inflammation-related diseases and cancer. In the present study, the inhibitory effect and possible mechanisms of diosgenin on superoxide generation were investigated in mouse bone marrow neutrophils. Diosgenin potently and concentration-dependently inhibited the extracellular and intracellular superoxide anion generation in Formyl-Met-Leu-Phe (FMLP)- activated neutrophils, with IC50 values of 0.50 ± 0.08 μM and 0.66 ± 0.13 μM, respectively. Such inhibition was not mediated by scavenging the superoxide anion or by a cytotoxic effect. Diosgenin inhibited the phosphorylation of p47phox and membrane translocation of p47phox and p67phox, and thus blocking the assembly of nicotinamide adenine dinucleotide phosphate oxidase. Moreover, cellular cyclic adenosine monophosphate (cAMP) levels and protein kinase A (PKA) expression were also effectively increased by diosgenin. It attenuated FMLP-induced increase of phosphorylation of cytosolic phospholipase A (cPLA2), p21-activated kinase (PAK), Akt, p38 mitogen-activated protein kinase (p38MAPK), extracellular signal-regulated kinase (ERK1/2), and c-Jun N-terminal kinase (JNK). Our data indicate that diosgenin exhibits inhibitory effects on superoxide anion production through the blockade of cAMP, PKA, cPLA2, PAK, Akt and MAPKs signaling pathways. The results may explain the clinical implications of diosgenin in the treatment of inflammation-related disorders.

  1. Superoxide dismutase prevents development of adenocarcinoma in a rat model of Barrett's esophagus

    Institute of Scientific and Technical Information of China (English)

    Elena Piazuelo; Carmelo Cebrián; Alfredo Escartín; Pilar Jiménez; Fernando Soteras; Javier Ortego; Angel Lanas

    2005-01-01

    AIM: To test whether antioxidant treatment could prevent the progression of Barrett's esophagus to adenocarcinoma.METHODS: In a rat model of gastroduodenoesophageal reflux by esophagojejunal anastomosis with gastric preservation, groups of 6-10 rats were randomized to receive treatment with superoxide dismutase (SOD) or vehicle and followed up for 4 mo. Rat's esophagus was assessed by histological analysis, superoxide anion and peroxinitrite generation, SOD levels and DNA oxidative damage.RESULTS: All rats undergoing esophagojejunostomy developed extensive esophageal mucosal ulceration and inflammation by mo 4. The process was associated with a progressive presence of intestinal metaplasia beyondthe anastomotic area (9% 1st mo and 50% 4th mo) (94% at the anastomotic level) and adenocarcinoma(11% 1st mo and 60% 4th mo). These changes were associated with superoxide anion and peroxinitrite mucosal generation, an early and significant increase of DNA oxidative damage and a significant decrease in SOD levels (P<0.05). Exogenous administration of SOD decreased mucosal superoxide levels, increased mucosal SOD levels and reduced the risk of developing intestinal metaplasia beyond the anastomotic area (odds ratio = 0.326; 95%CI: 0.108-0.981; P = 0.046),and esophageal adenocarcinoma (odds ratio = 0.243;95%CI: 0.073-0.804; P = 0.021).CONCLUSION: Superoxide dismutase prevents the progression of esophagitis to Barrett's esophagus and adenocarcinoma in this rat model of gastrointestinal reflux, supporting a role of antioxidants in the chemoprevention of esophageal adenocarcinoma.

  2. Rebamipide attenuates nonsteroidal anti-inflammatory drugs (NSAID) induced lipid peroxidation by the manganese superoxide dismutase (MnSOD) overexpression in gastrointestinal epithelial cells.

    Science.gov (United States)

    Nagano, Y; Matsui, H; Shimokawa, O; Hirayama, A; Tamura, M; Nakamura, Y; Kaneko, T; Rai, K; Indo, H P; Majima, H J; Hyodo, I

    2012-04-01

    Nonsteroidal anti-inflammatory drugs (NSAIDs) often cause gastrointestinal complications such as gastric ulcers and erosions. Recent studies on the pathogenesis have revealed that NSAIDs induce lipid peroxidation in gastric epithelial cells by generating superoxide anion in mitochondria, independently with cyclooxygenase-inhibition and the subsequent prostaglandin deficiency. Although not clearly elucidated, the impairment of mitochondrial oxidative phosphorylation, or uncoupling, by NSAIDs is associated with the generation of superoxide anion. Physiologically, superoxide is immediately transformed into hydrogen peroxide and diatomic oxygen with manganese superoxide dismutase (MnSOD). Rebamipide is an antiulcer agent that showed protective effects against NSAID-induced lipid peroxidation in gastrointestinal tracts. We hypothesized that rebamipide may attenuate lipid peroxidation by increasing the expression of MnSOD protein in mitochondria and decreasing the leakage of superoxide anion in NSAID-treated gastric and small intestinal epithelial cells. Firstly, to examine rebamipide increases the expression of MnSOD proteins in mitochondria of gastrointestinal epithelial cells, we underwent Western blotting analysis against anti-MnSOD antibody in gastric RGM1 cells and small intestinal IEC6 cells. Secondly, to examine whether the pretreatment of rebamipide decreases NSAID-induced mitochondrial impairment and lipid peroxidation, we treated these cells with NSAIDs with or without rebamipide pretreatment, and examined with specific fluorescent indicators. Finally, to examine whether pretreatment of rebamipide attenuates NSAID-induced superoxide anion leakage from mitochondria, we examined the mitochondria from indomethacin-treated RGM1 cells with electron spin resonance (ESR) spectroscopy using a specific spin-trapping reagent, CYPMPO. Rebamipide increased the expression of MnSOD protein, and attenuated NSAID-induced mitochondrial impairment and lipid peroxidation in RGM1

  3. Copper-catalyzed activation of molecular oxygen for oxidative destruction of acetaminophen: The mechanism and superoxide-mediated cycling of copper species.

    Science.gov (United States)

    Zhang, Yunfei; Fan, Jinhong; Yang, Bo; Huang, Wutao; Ma, Luming

    2017-01-01

    In this study, the commercial zero-valent copper (ZVC) was investigated to activate the molecular oxygen (O2) for the degradation of acetaminophen (ACT). 50 mg/L ACT could be completely decomposed within 4 h in the ZVC/air system at initial pH 3.0. The H2O2, hydroxyl radical (OH) and superoxide anion radical (O2(-)) were identified as the main reactive oxygen species (ROSs) generated in the above reaction; however, only OH caused the decomposition and mineralization of ACT in the copper-catalyzed O2 activation process. In addition, the in-situ generated Cu(+) from ZVC dissolution not only activated O2 to produce H2O2, but also initiated the decomposition of H2O2 to generate OH. Meanwhile, the H2O2 could also be partly decomposed into O2(-), which served as a mediator for copper cycling by reduction of Cu(2+) to Cu(+) in the ZVC/air system. Therefore, OH could be continuously generated; and then ACT was effectively degraded. Additionally, the effect of solution pH and the dosage of ZVC were also investigated. As a result, this study indicated the key behavior of the O2(-) during Cu-catalyzed activation of O2, which further improved the understanding of O2 activation mechanism by zero-valent metals. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Superoxide microsensor integrated into a Sensing Cell Culture Flask microsystem using direct oxidation for cell culture application.

    Science.gov (United States)

    Flamm, H; Kieninger, J; Weltin, A; Urban, G A

    2015-03-15

    A new electrochemical sensor system for reliable and continuous detection of superoxide radical release from cell culture was developed utilizing direct oxidation of superoxide on polymer covered gold microelectrodes. Direct superoxide oxidation was demonstrated to provide robust measurement principle for sensitive and selective reactive oxygen species (ROS) quantification without the need for biocomponent supported conversion. Sensor performance was investigated by using artificial enzymatic superoxide production revealing a sensitivity of 2235AM(-1)m(-2). An electrode protection layer with molecular weight cut-off property from adsorbed linear branched polyethylenimine was successfully introduced for long term and selectivity improvement. Thin-film based sensor chip fabrication with implemented three-electrode setup and full integration into the technological platform Sensing Cell Culture Flask was described. Cell culturing directly on-chip and free radical release by phorbol-12-myristate-13-acetate (PMA) stimulation was demonstrated using T-47D human breast cancer carcinoma cell model. Transient extracellular superoxide production upon stimulation was successfully observed from amperometric monitoring. Signal inhibition from scavenging of extracellular superoxide by specific superoxide dismutase (SOD) showed the applicability for selective in vitro ROS determination. The results confirm the possibility of direct superoxide oxidation, with exclusion of the main interfering substances uric acid and hydrogen peroxide. This offers new insights into the development of reliable and robust ROS sensors.

  5. A new formula to calculate activity of superoxide dismutase in indirect assays.

    Science.gov (United States)

    Zhang, Chen; Bruins, Marieke E; Yang, Zhi-Qiang; Liu, Shu-Tao; Rao, Ping-Fan

    2016-06-15

    To calculate superoxide dismutase (SOD) activity rapidly and accurately by indirect SOD assays, a formula based on the ratio of the catalytic speed of SOD to the reaction speed of the indicator with superoxide anion was deduced. The accuracy of this formula was compared with the conventional formula based on inhibition in five indirect SOD assays. The new formula was validated in nearly the entire SOD activity range, whereas the conventional formula was validated only during inhibition of 40-60%. This formula might also be used for the assays of other enzymes.

  6. Cryo-Trapping the Distorted Octahedral Reaction Intermediate of Manganese Superoxide Dismutase

    Science.gov (United States)

    Borgstahl, Gloria; Snell, Edward H.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Superoxide dismutase protects organisms from potentially damaging oxygen radicals by catalyzing the disproportion of superoxide to oxygen and hydrogen peroxide. We report the use of cryogenic temperatures to kinetically trap the 6th ligand bound to the active site of manganese superoxide dismutase. Using cryocrystallography and synchrotron radiation, we describe at 1.55A resolution the six-coordinate, distorted octahedral geometry assumed by the active site during catalysis and compare it to the room temperature, five-coordinate trigonal-bipyramidal active site. Gateway residues Tyr34, His30 and a tightly bound water molecule are implicated in closing off the active site and blocking the escape route of superoxide during dismutation.

  7. The cellular distribution of extracellular superoxide dismutase in macrophages is altered by cellular activation but unaffected by the natural occurring R213G substitution

    DEFF Research Database (Denmark)

    Gottfredsen, Randi Heidemann; Goldstrohm, David; Hartney, John

    2014-01-01

    Extracellular superoxide dismutase (EC-SOD) is responsible for the dismutation of the superoxide radical produced in the extracellular space and known to be expressed by inflammatory cells, including macrophages and neutrophils. Here we show that EC-SOD is produced by resting macrophages...

  8. Impact of antiseptics on radical metabolism, antioxidant status and genotoxic stress in blood cells: povidone-iodine versus octenidine dihydrochloride.

    Science.gov (United States)

    Wagner, Karl-Heinz; Jürss, Alice; Zarembach, Beate; Elmadfa, Ibrahim

    2004-08-01

    No sufficient data are available of the of antiseptics' influence on human blood cells. Effects of two antiseptics, povidone-iodine (PVD-I) versus octenidine dihydrochloride (OD), were tested on antioxidant status, radical formation, antioxidant defence enzymes and genotoxic stress in blood cells, in vitro. Human blood was taken by venipuncture, enriched with PVD-I or OD (0.0001-20% final concentration) and incubated at 37 degrees C between 30 and 120 min. alpha-Tocopherol was assessed in erythrocytes and granulocytes. Superoxide-dismutase (SOD) and glutathione (GSH) were determined in erythrocytes, the total anti-oxidative capacity (TAC) and malondialdehyde (MDA) in their ghosts. In granulocytes status of hydrogen peroxide (H(2)O(2)), superoxide anions and MDA was observed. Genotoxic stress was determined by counting sister chromatide exchanges (SCE) in lymphocytes after enrichment within 0.05-0.4% of antiseptics. Based on all biomarker tested, concentrations up to 0.05% incubated for 30 min did not affect cell metabolism. 1% and 10% PVD-I reduced the activity of SOD (-40%), GSH (-62%) and the content of alpha-tocopherol more than OD (p<0.05). No significant differences between the antiseptics were observed for TAC and MDA. H(2)O(2) and superoxide anions were significantly reduced after the 10% addition for both substances independent on the exposure. Without having changes in lipid oxidation, the reduction of antioxidative defence mechanisms must be due to the oxidation caused by the antiseptics, mainly PVD-I. An increased SCE rate was neither observed with PVD-I nor with OD within an enrichment with 0.05-0.4%. Higher concentrations (1% and more) could not be tested on SCE formation because they caused cell bursts. The results presented indicate that concentrations up to 0.05% incubated for 30 min are safe for exposing blood cells of healthy subjects.

  9. Theoretical Investigation on Radical-Coupling Reactivity of Indolinonic Aminoxyls

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Indolinonic aminoxyls can effectively scavenge various radicals by directly coupling with them or by imitating superoxide dismutase. To better understand the radical-coupling reactions, DFT method B3LYP/6-31G(d,p) was employed to calculate variations of free energy for the coupling reactions and other physico-chemical parameters. The radical-coupling activity difference between aminoxyls was elucidated to a large extent in terms of electronic properties of substituents.

  10. The Superoxide Reductase from the Early Diverging Eukaryote Giardia Intestinalis

    Energy Technology Data Exchange (ETDEWEB)

    Cabelli, D.E.; Testa, F.; Mastronicola, D.; Bordi, E.; Pucillo, L.P.; Sarti, P.; Saraiva, L.M.; Giuffre, A.; Teixeira, M.

    2011-10-15

    Unlike superoxide dismutases (SODs), superoxidereductases (SORs) eliminate superoxide anion (O{sub 2}{sup {sm_bullet}-}) not through its dismutation, but via reduction to hydrogen peroxide (H{sub 2}O{sub 2}) in the presence of an electron donor. The microaerobic protist Giardia intestinalis, responsible for a common intestinal disease in humans, though lacking SOD and other canonical reactive oxygen species-detoxifying systems, is among the very few eukaryotes encoding a SOR yet identified. In this study, the recombinant SOR from Giardia (SOR{sub Gi}) was purified and characterized by pulse radiolysis and stopped-flow spectrophotometry. The protein, isolated in the reduced state, after oxidation by superoxide or hexachloroiridate(IV), yields a resting species (T{sub final}) with Fe{sup 3+} ligated to glutamate or hydroxide depending on pH (apparent pK{sub a} = 8.7). Although showing negligible SOD activity, reduced SOR{sub Gi} reacts with O{sub 2}{sup {sm_bullet}-} with a pH-independent second-order rate constant k{sub 1} = 1.0 x 10{sup 9} M{sup -1} s{sup -1} and yields the ferric-(hydro)peroxo intermediate T{sub 1}; this in turn rapidly decays to the T{sub final} state with pH-dependent rates, without populating other detectable intermediates. Immunoblotting assays show that SOR{sub Gi} is expressed in the disease-causing trophozoite of Giardia. We propose that the superoxide-scavenging activity of SOR in Giardia may promote the survival of this air-sensitive parasite in the fairly aerobic proximal human small intestine during infection.

  11. 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.

  12. Catalytic Radical Domino Reactions in Organic Synthesis

    Science.gov (United States)

    Sebren, Leanne J.; Devery, James J.; Stephenson, Corey R.J.

    2014-01-01

    Catalytic radical-based domino reactions represent important advances in synthetic organic chemistry. Their development benefits synthesis by providing atom- and step-economical methods to complex molecules. Intricate combinations of radical, cationic, anionic, oxidative/reductive, and transition metal mechanistic steps result in cyclizations, additions, fragmentations, ring-expansions, and rearrangements. This Perspective summarizes recent developments in the field of catalytic domino processes. PMID:24587964

  13. 白藜芦醇对衰老小鼠GSH和抗超氧阴离子自由基含量变化的影响%Effect of resveratrol on content of GSH and anti super oxide anion radical of naturally senile mice

    Institute of Scientific and Technical Information of China (English)

    张效莉; 吴景东

    2011-01-01

    目的:研究白藜芦醇对皮肤的抗衰老作用.方法:健康4月龄昆明种小鼠12只,作为青年对照组(A);健康18月龄昆明种小鼠60只,随机分成5组:老年空白对照组(B)、老年阳性对照组(C)、老年绞股蓝皂苷时照组(D)、老年白藜芦醇高剂量组(E)、老年白藜芦醇低剂量组(F).每日灌胃给药,以生化分析方法测定GSH及抗超氧阴离子自由基含量.结果:与青年对照组对比其余五个老年组的GSH和抗超氧阴离子自由基含量在药物的作用下明显提高.结论:白藜芦醇能够延缓小鼠的衰老.%Objective To study if resveratrol have function on delaying naturally senile mice or not. Methods 12 kind of Kunming age in four-month female small mice contrast a group as youth (A),60 kind of Kunmlng age in eighteen-month female small mice at random divides 5 group, 12 for a group: Old age blank group (B),old age masculine group(C),old age gypenoside group(D),resveratrol high dose(E),resveratrol low dose(F).Filling the stomach with medicine. Determine the content of GSH and anti super oxide anion radical. Results Compares with the youth group,the other five old age group can enhance the content of GSH and anti super oxide anion radical. Conclusion Resveratrol have function on delaying naturally senile mice.

  14. Impact of Thyroid Dysfunction on Antioxidant Capacity, Superoxide Dismutase

    Directory of Open Access Journals (Sweden)

    Mehdi Hedayati

    2014-01-01

    Full Text Available Background: In hypothyroidism and hyperthyroidism, disturbance of oxidant/antioxidant balance leads to reactive oxygen species (ROS generation. The aim of this study is assaying total antioxidant capacity and superoxide dismutase and catalase activities in patients with hypo-and hyperthyroidism in order to control the progression of its pathology and health care. Materials and Methods: This case-control study was performed on 85 patients with hypothyroidism, 66 patients with hyperthyroidism and 74 normal individuals as control that referred to the clinic of the Research Institute for Endocrine Sciences of Shahid-Beheshti University in year 2010. Serum enzymatic activity of catalase, superoxide dismutase and total antioxidant capacity was measured in the fasting state. Data was described as mean±SD and data means of the two groups was compared by independent t-test. Data was analyzed by SPSS-18 application. Results: The total antioxidant capacity in individuals with hyperthyroidism decreased compared to healthy controls, but individuals with hypothyroidism compared to the healthy control group showed no significant difference. Catalase and superoxide dismutase activity in hypo-and hyperthyroidism were significantly increased compared with healthy controls (p=0.005. Conclusion: Decreasing of antioxidant capacity in hyperthyroid patients is probably because of increased production of free radicals. There was not observed significant difference in total antioxidant capacity in hypothyroid patients. Also in hypo-and hyperthyroidism patients, increasing of enzymes activity is probably due to increasing of the production of ROS.

  15. Macroporous mesh of nanoporous gold in electrochemical monitoring of superoxide release from skeletal muscle cells.

    Science.gov (United States)

    Banan Sadeghian, Ramin; Han, Jiuhui; Ostrovidov, Serge; Salehi, Sahar; Bahraminejad, Behzad; Ahadian, Samad; Chen, Mingwei; Khademhosseini, Ali

    2017-02-15

    Real-time monitoring of metabolically relevant biochemicals released in minuscule amounts is of utmost diagnostic importance. Superoxide anion as a primary member of reactive oxygen species, has physiological and pathological effects that depend on its concentration and release rate. Here we present fabrication and successfully testing of a highly sensitive electrochemical biosensor featuring a three-dimensional macroporous mesh of nanoporous gold tailored to measure the dynamics of extracellular superoxide concentration. Wide and accessible surface of the mesh combined with high porosity of the thin nanoporous gold coating enables capturing the analyte in pico- to nano-molar ranges. The mesh is functionalized with cytochrome-c (cyt-c) and incorporated as a working electrode to measure the release rate of drug-induced superoxides from C2C12 cells through a porous membrane. The device displays a considerably improved superoxide sensitivity of 7.29nAnM(-)(1)cm(-)(2) and a low level of detection of 70pM. Such sensitivity is orders of magnitude higher than any similar enzyme-based electrochemical superoxide sensor and is attributed to the facile diffusion of the analyte through the well-spread nanofeatured gold skin. Superoxide generation rates captured from monolayer myoblast cultures containing about 4×10(4) cells, varied from 1.0 to 9.0nMmin(-)(1) in a quasi-linear fashion as a function of drug concentration. This work provides a platform for the development of highly sensitive molecular electrochemical biosensors.

  16. Anionic clusters in dusty hydrocarbon and silane plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Hollenstein, C.; Schwarzenbach, W.; Howling, A.A.; Courteille, C.; Dorier, J.L.; Sansonnens, L. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)

    1995-10-01

    Measurements of anions and cations are reported for hydrocarbon and silane rf capacitive glow discharges. Series of anions were observed by quadrupole mass spectrometry using power-modulated plasmas and their structures are interpreted from the form of the mass spectra. Various experiments in silane plasmas show that anion confinement results in particles and conversely, anion de-trapping can inhibit particle formation. In contrast, the polymerized neutral flux magnitudes, mass spectra and dynamics are independent of the powder formation. Powder is known to form readily in deposition plasmas containing electronegative free radicals, and the general role of anions in particle formation is discussed in the light of these experiments. (author) 6 figs., 21 refs.

  17. Iron-responsive regulation of the Helicobacter pylori iron-cofactored superoxide dismutase SodB is mediated by Fur.

    NARCIS (Netherlands)

    F.D.J. Ernst (Florian); G. Homuth (Georg); J. Stoof (Jeroen); U. Mader; B. Waidner (Barbara); E.J. Kuipers (Ernst); M. Kist (Manfred); J.G. Kusters (Johannes); S. Bereswill (Stefan); A.H.M. van Vliet (Arnoud)

    2005-01-01

    textabstractMaintaining iron homeostasis is a necessity for all living organisms, as free iron augments the generation of reactive oxygen species like superoxide anions, at the risk of subsequent lethal cellular damage. The iron-responsive regulator Fur controls iron metabolism in many bacteria, inc

  18. Production of superoxide and activity of superoxide dismutase in rabbit epididymal spermatozoa.

    Science.gov (United States)

    Holland, M K; Alvarez, J G; Storey, B T

    1982-12-01

    Mature rabbit spermatozoa from the cauda epididymidis suspended in potassium Tris phosphate buffer at 24 degrees C produced O2.-, as measured by reduction of acetylated ferricytochrome c, with an intrinsic rate of 0.20 nmol/min per 10(8) cells. This rate increased to 1.80 nmol/min per 10(8) cells in the presence of 10 mM cyanide. These spermatozoa contain 2.8 units per 10(8) cells of superoxide dismutase activity, 95% of which is sensitive, and 5% of which is insensitive, to cyanide inhibition. These activities correspond to the cytosolic Cu-Zn form and the mitochondrial Mn form of the dismutase, respectively. Only the cyanide-sensitive form is released from the sperm on hypo-osmotic treatment or sonication. Hypo-osmotically treated rabbit epididymal spermatozoa produced O2.- with an intrinsic rate of 0.24 nmol/min per 10(8) cells, which increased to 0.58 nmol/min per 10(8) cells in the presence of 10 mM cyanide. Both intact and hypo-osmotically treated cells react with O2.- in a second order reaction as inferred from the hyperbolic dependence on cell concentration of O2.- production rate in both the absence and presence of cyanide. The second order rate constant for this reaction with intact cells, kS, was calculated to be 22.9 X 10(-8) (cells/ml)-1 min-1 in its absence. For hypo-osmotically treated cells, the values of kS were 10.8 X 10(-8) (cells/ml)-1 min-1 and 8.2 X 10(-8) (cells/ml) -1 min-1, respectively. Since hypo-osmotically treated cells have lost much of their plasma membrane, the lower value of kS for the treated cells implies that this membrane is one site of reaction of O2.- with the cells. The increase in kS in the presence of cyanide, which inhibits superoxide dismutase and so increases O2.- production, suggests that the cells become more reactive with O2.- as its production rate increase, as would be expected for the occurrence of radical chain oxidation. This in turn suggests that superoxide dismutase plays a major role in protecting rabbit sperm

  19. Detoxification of superoxide without production of H2O2: antioxidant activity of superoxide reductase complexed with ferrocyanide

    CERN Document Server

    Molina-Heredia, Fernando P; Berthomieu, Catherine; Touati, Danièle; Tremey, Emilie; Favaudon, Vincent; Adam, Virgile; Nivière, Vincent

    2015-01-01

    The superoxide radical O(2)(-.) is a toxic by-product of oxygen metabolism. Two O(2)(-.) detoxifying enzymes have been described so far, superoxide dismutase and superoxide reductase (SOR), both forming H2O2 as a reaction product. Recently, the SOR active site, a ferrous iron in a [Fe(2+) (N-His)(4) (S-Cys)] pentacoordination, was shown to have the ability to form a complex with the organometallic compound ferrocyanide. Here, we have investigated in detail the reactivity of the SOR-ferrocyanide complex with O(2)(-.) by pulse and gamma-ray radiolysis, infrared, and UV-visible spectroscopies. The complex reacts very efficiently with O(2)(-.). However, the presence of the ferrocyanide adduct markedly modifies the reaction mechanism of SOR, with the formation of transient intermediates different from those observed for SOR alone. A one-electron redox chemistry appears to be carried out by the ferrocyanide moiety of the complex, whereas the SOR iron site remains in the reduced state. Surprisingly, the toxic H2O2 s...

  20. Ion-radical intermediates of the radiation-chemical transformations of organic carbonates

    Science.gov (United States)

    Shiryaeva, Ekaterina S.; Sosulin, Ilya S.; Saenko, Elizaveta V.; Feldman, Vladimir I.

    2016-07-01

    The spectral features and reactions of ion-radical intermediates produced from organic carbonates in low-temperature matrices were investigated by EPR spectroscopy and quantum-chemical calculations. It was shown that radical cations of diethyl carbonate and dimethyl carbonate underwent intramolecular hydrogen transfer to yield alkyl-type species, as was suggested previously. Meanwhile, radical cation of EC demonstrates a ring cleavage even at 77 K, while radical cation of PC is probably intrinsically stable and undergo an ion-molecule reaction with a neighboring neutral molecule in dimers or associates. Radical anions were obtained in glassy matrices of diethyl ether or perdeuteroethanol. The radical anions of linear carbonates show photoinduced fragmentation to yield the corresponding alkyl radicals; such process may also occur directly under radiolysis. Radical anions of cyclic carbonates are relatively stable and yield only trace amounts of fragmentation products under similar conditions.

  1. Spontaneous Binding of Molecular Oxygen at the Qo-Site of the bc1 Complex Could Stimulate Superoxide Formation

    DEFF Research Database (Denmark)

    Husen, Peter; Solov'yov, Ilia A

    2016-01-01

    to drive ATP synthesis. This molecular machinery, however, is suspected to be a source of superoxide, which is toxic to the cell, even in minuscular quantities, and believed to be a factor in aging. Through molecular dynamics simulations, we investigate here the migration of molecular oxygen in the bc1...... complex in order to identify possible reaction sites that could lead to superoxide formation. It is found, in particular, that oxygen penetrates spontaneously the Qo binding site of the bc1 complex in the presence of an intermediate semiquinone radical, thus making the Qo-site a strong candidate for being...... a center of superoxide production....

  2. The different behavior of rutile and anatase nanoparticles in forming oxy radicals upon illumination with visible light: an EPR study.

    Science.gov (United States)

    Lipovsky, Anat; Levitski, Luba; Tzitrinovich, Zeev; Gedanken, Aharon; Lubart, Rachel

    2012-01-01

    Photoexcited TiO(2) has been found to generate reactive oxygen species, yet the precise mechanism and chemical nature of the generated oxy species especially regarding the different crystal phases remain to be elucidated. Visible light-induced reactions of a suspension of titanium dioxide (TiO(2)) in water were investigated using electron paramagnetic resonance (EPR) coupled with the spin-trapping technique. Increased levels of both hydroxyl (˙OH) and superoxide anion (˙O(2)(-)) radicals were detected in TiO(2) rutile and anatase nanoparticles (50 nm). The intensity of signals assigned to the ˙OH and ˙O(2)(-) radicals was larger for the anatase phase than that originating from rutile. Moreover, illumination with visible (nonUV) light enhanced ˙O(2)(-) formation in the rutile phase. Singlet oxygen was not detected in water suspension of TiO(2) neither in rutile nor in anatase nanoparticles, but irradiation of the rutile phase with visible light revealed a signal, which could be attributed to singlet oxygen formation. The blue part of visible spectrum (400-500 nm) was found to be responsible for the light-induced ROS in TiO(2) nanoparticles. The characterization of the mechanism of visible light-induced oxy radicals formation by TiO(2) nanoparticles could contribute to its use as a sterilization agent.

  3. Fast Resonance Raman Spectroscopy of Short-Lived Radicals

    DEFF Research Database (Denmark)

    Pagsberg, Palle Bjørn; Wilbrandt, Robert Walter; Hansen, Karina Benthin

    1976-01-01

    We report the first application of pulsed resonance Raman spectroscopy to the study of short-lived free radicals produced by pulse radiolysis. A single pulse from a flash-lamp pumped tunable dye laser is used to excite the resonance Raman spectrum of the p-terphenyl anion radical with an initial...

  4. 碧萝芷对辐射所致小鼠各脏器中自由基的清除作用%Scavenging Effect of Pycnogenol on Free Radicals in Radiation Exposed Mice Organs

    Institute of Scientific and Technical Information of China (English)

    丁翔; 强亦忠; 王利利; 程跃进; 江家贵; 崔凤梅

    2011-01-01

    目的 观察碧萝芷对60Coγ射线整体照射所致小鼠主要脏器中超氧化物歧化酶( superoxide dismutase,SOD)活力、丙二醛(malondialdehyde,MDA)含量、抗超氧阴离子自由基能力和抑制羟自由基能力的影响.方法 小鼠随机分成3组:正常对照组,辐照对照组及碧萝芷实验组.辐照对照组及碧萝芷实验组各接受1次γ射线照射,同时碧萝芷实验组用碧萝芷灌胃,连续7d.处死后取肝、脾、肾和睾丸组织,测定SOD活力、MDA含量、抑制羟自由基能力和抗超氧阴离子自由基能力.结果 碧萝芷对受照小鼠脏器中SOD活力影响不大,可降低脏器中MDA含量;能增加肝脏、肾脏和睾丸组织中抗超氧阴离子自由基能力和抑制羟自由基能力,增加脾脏抑制羟自由基能力.结论 碧萝芷具有一定的抗辐射损伤作用,其通过直接中和超氧阴离子自由基和羟自由基而发挥抗氧化功能,并不增加组织中的抗氧化酶含量.%Objective To observe the effects of pycnogenol on contents of SOD and MDA, and the inhibition of superoxide anion and hydroxyl radical in '"Co y-ray exposed mice organs. Methods The mice were randomly divided into 3 groups I. E. The normal control, irradiation control and pycnogenol experiment groups. The irradiation control and pycnogenol experiment groups were exposed to 60Co y- ray, and the mice of pycnogenol experiment group were given pycnogenol for 7 days after radiation. The tissues were obtained after being sacrificed, in which the vitality of SOD, the content of MDA and the inhibition of superoxide anion and hydroxyl radical were detected. Results Results showed that after the mice were irradiated pycnogenol had no effect on SOD; however, the content of MDA could be reduced in organs. Pycnogenol could increase the inhibition of superoxide anion and hydroxyl radical in kidney, liver and testicular and could increase the inhibition of hydroxyl radical in spleen. Conclusions Pycnogenol shows

  5. Modeling and analysis of soybean (Glycine max. L Cu/Zn, Mn and Fe superoxide dismutases

    Directory of Open Access Journals (Sweden)

    V. Ramana Gopavajhula

    2013-01-01

    Full Text Available Superoxide dismutase (SOD, EC 1.15.1.1 is an important metal-containing antioxidant enzyme that provides the first line of defense against toxic superoxide radicals by catalyzing their dismutation to oxygen and hydrogen peroxide. SOD is classified into four metalloprotein isoforms, namely, Cu/Zn SOD, Mn SOD, Ni SOD and Fe SOD. The structural models of soybean SOD isoforms have not yet been solved. In this study, we describe structural models for soybean Cu/Zn SOD, Mn SOD and Fe SOD and provide insights into the molecular function of this metal-binding enzyme in improving tolerance to oxidative stress in plants.

  6. Effects of Acetosalicylic Acid on Levels of Superoxide Anion and Peroxidation of Membrane Lipid in Rice Seedlings Under Nickel-Stress%乙酰水杨酸对镍胁迫下水稻幼苗中O-2水平和膜脂过氧化的影响

    Institute of Scientific and Technical Information of China (English)

    王海华; 蒋明义; 康健; 彭喜旭; 帕尼古丽

    2001-01-01

    采用室内培养及生理指标测定方法,研究了乙酰水杨酸对镍胁迫下水稻幼苗中部分生理指标的影响。结果表明, 10 μ mol· L- 1和 30 μ mol· L- 1的镍胁迫下,稻苗叶片中 SOD活性明显降低,质外体中的 NADH氧化酶活性显著上升;同时,细胞中总和质外体中产生明显加快,从而导致叶片组织中 MDA含量和质膜透性亦明显增加。同样胁迫条件下,加入 0.05% ASA, SOD活性回升,产生速率回落, MDA含量和质膜透性增加的程度亦减小,但乙酰水杨酸 (ASA)对质外体中 NADH氧化酶活性无明显影响。这些结果提示产生与积累导致的膜脂过氧化作用介导了镍对稻苗的毒害; ASA能降低产生速率,减轻膜脂过氧化损伤程度,因而缓解了镍胁迫对稻苗的毒害%Two stress concentrations of nickel tested (10,30 μ mol· L- 1) significantly decreased superoxide dismutase (SOD) activity in rice leaves, while enhanced NADH oxidase activity significantly in apoplast. Measurement of, malondialdehyde(MDA), relative electric conductivity showed that there was a significantly increase in both totalgeneration rate and that of apoplast, as well as in MDA content and the plasma membrane permeability after nickel treatment. Addition of 0.05 % acetylsalicylic (ASA) to the same nickel stress condition decreased the rate of decline in SOD activity, and that of increase in generation, MDA content and the plasma permeability observed in rice leaves treated with nickel alone. However, no changes in apoplast NADH oxidase activity were observed. The results suggested that accumulation and membrane lipid peroxidation were involved in the toxicity to rice seedlings led by nickel, and the decline in level and membrane lipid peroxidation were the reasons by which ASA mitigated the injuries induced by nickel stress in rice seedlings.

  7. The two spin states of an end-on copper(II)-superoxide mimic.

    Science.gov (United States)

    Askari, Mohammad S; Girard, Brigitte; Murugesu, Muralee; Ottenwaelder, Xavier

    2011-07-28

    The reaction of nitrosobenzene with copper(I) complexes of a tetradentate ligand led to two novel species that are best described as copper(II) complexes of an O-bonded nitrosobenzyl radical anion, in either the singlet or the triplet spin-state. Both states were characterized by crystal structures, magnetic measurements and DFT calculations.

  8. Radical scavenging potentials of single and combinatorial herbal formulations in vitro

    OpenAIRE

    2015-01-01

    Reactive oxygen and nitrogen species (RONS) are involved in deleterious/beneficial biological processes. The present study sought to investigate the capacity of single and combinatorial herbal formulations of Acanthus montanus, Emilia coccinea, Hibiscus rosasinensis, and Asystasia gangetica to act as superoxide radicals (SOR), hydrogen peroxide (HP), nitric oxide radical (NOR), hydroxyl radical (HR), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical antagonists using in vitro models. The herba...

  9. Myocardial capillary permeability after regional ischemia and reperfusion in the in vivo canine heart. Effect of superoxide dismutase

    DEFF Research Database (Denmark)

    Svendsen, Jesper Hastrup; Bjerrum, P J; Haunsø, S

    1991-01-01

    This study assesses the effect of the superoxide anion scavenger superoxide dismutase on myocardial capillary permeability-surface area (PS) products for small hydrophilic molecules after ischemia and reperfusion. Open-chest dogs underwent a 20-minute occlusion of the left anterior descending...... the start of reperfusion. In 13 dogs, no scavenger treatment was given (nonprotected control group), whereas eight dogs were treated systemically with 15,000 units/kg superoxide dismutase during 1 hour, starting 20 minutes before ischemia. In the control group, three dogs developed reperfusion ventricular...... fibrillation in contrast to none in the superoxide dismutase group. Before ischemia, plasma flow rate, myocardial capillary extraction fraction, and PS values were similar in the two groups. Five minutes after the start of reperfusion, plasma flow rate increased significantly (p less than 0.01) in both groups...

  10. Activation of Mitochondrial Uncoupling Protein 4 and ATP-Sensitive Potassium Channel Cumulatively Decreases Superoxide Production in Insect Mitochondria.

    Science.gov (United States)

    Slocińska, Malgorzata; Rosinski, Grzegorz; Jarmuszkiewicz, Wieslawa

    2016-01-01

    It has been evidenced that mitochondrial uncoupling protein 4 (UCP4) and ATP-regulated potassium channel (mKATP channel) of insect Gromphadorhina coqereliana mitochondria decrease superoxide anion production. We elucidated whether the two energy-dissipating systems work together on a modulation of superoxide level in cockroach mitochondria. Our data show that the simultaneous activation of UCP4 by palmitic acid and mKATP channel by pinacidil revealed a cumulative effect on weakening mitochondrial superoxide formation. The inhibition of UCP4 by GTP (and/or ATP) and mKATP channel by ATP elevated superoxide production. These results suggest a functional cooperation of both energy-dissipating systems in protection against oxidative stress in insects.

  11. A superoxide dismutase of metacestodes of Taenia taeniaeformis.

    Science.gov (United States)

    Leid, R W; Suquet, C M

    1986-03-01

    Superoxide dismutase was purified from Taenia taeniaeformis metacestodes by sequential ion exchange chromatography on quaternary-amino-ethyl-cellulose, gel filtration chromatography on ACA 44 and ion exchange chromatography on DEAE-cellulose, followed by chromatofocusing on polybuffer exchanger 94. This isolation procedure resulted in the detection of a single protein-staining band on alkaline gels, coincident with enzyme activity. We have, however, detected what appear to be two peaks of enzyme activity within this single protein-staining band. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis using gradient slab gels and analysis under reducing conditions, resulted in the detection of only one protein at an apparent Mr of 16,600, while analysis under non-reducing conditions, gave a single protein of an apparent Mr of 64,000. The isoelectric point of the purified protein is 6.6. Boiling for 3 min completely destroyed the enzyme, whereas incubation for 2 h at 37 degrees C resulted in the loss of 56% of the enzymic activity. Incubation with 10 mM KCN resulted in 83% inhibition of the enzyme. We have detected up to 168 U ml-1 of enzyme activity in the cyst fluid surrounding the parasite in situ. This is the first instance in which any parasite superoxide dismutase has been purified to apparent homogeneity. Parasite-mediated enzymic destruction of superoxide anion can not only protect against oxygen toxicity as a result of normal parasite respiratory processes but also may serve as yet another mechanism used by tissue-dwelling parasites to evade host immunologic attack.

  12. Superoxide dismutases in chronic gastritis.

    Science.gov (United States)

    Švagelj, Dražen; Terzić, Velimir; Dovhanj, Jasna; Švagelj, Marija; Cvrković, Mirta; Švagelj, Ivan

    2016-04-01

    Human gastric diseases have shown significant changes in the activity and expression of superoxide dismutase (SOD) isoforms. The aim of this study was to detect Mn-SOD activity and expression in the tissue of gastric mucosa, primarily in chronic gastritis (immunohistochemical Helicobacter pylori-negative gastritis, without other pathohistological changes) and to evaluate their possible connection with pathohistological diagnosis. We examined 51 consecutive outpatients undergoing endoscopy for upper gastrointestinal symptoms. Patients were classified based on their histopathological examinations and divided into three groups: 51 patients (archive samples between 2004-2009) with chronic immunohistochemical Helicobacter pylori-negative gastritis (mononuclear cells infiltration were graded as absent, moderate, severe) divided into three groups. Severity of gastritis was graded according to the updated Sydney system. Gastric tissue samples were used to determine the expression of Mn-SOD with anti-Mn-SOD Ab immunohistochemically. The Mn-SOD expression was more frequently present in specimens with severe and moderate inflammation of gastric mucosa than in those with normal mucosa. In patients with normal histological finding, positive immunoreactivity of Mn-SOD was not found. Our results determine the changes in Mn-SOD expression occurring in the normal gastric mucosa that had undergone changes in the intensity of chronic inflammatory infiltrates in the lamina propria. © 2016 APMIS. Published by John Wiley & Sons Ltd.

  13. Superoxide Dismutase 1 Loss Disturbs Intracellular Redox Signaling, Resulting in Global Age-Related Pathological Changes

    Directory of Open Access Journals (Sweden)

    Kenji Watanabe

    2014-01-01

    Full Text Available Aging is characterized by increased oxidative stress, chronic inflammation, and organ dysfunction, which occur in a progressive and irreversible manner. Superoxide dismutase (SOD serves as a major antioxidant and neutralizes superoxide radicals throughout the body. In vivo studies have demonstrated that copper/zinc superoxide dismutase-deficient (Sod1−/− mice show various aging-like pathologies, accompanied by augmentation of oxidative damage in organs. We found that antioxidant treatment significantly attenuated the age-related tissue changes and oxidative damage-associated p53 upregulation in Sod1−/− mice. This review will focus on various age-related pathologies caused by the loss of Sod1 and will discuss the molecular mechanisms underlying the pathogenesis in Sod1−/− mice.

  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...... surgery and at follow-up and they were asked to report their use of pads/diapers. Potency was defined as an IIEF-5 score of at least 17 with or without phosphodiesterase-5 inhibitors. Patients using up to one pad daily for security reasons only were considered continent. Positive surgical margins, blood...... loss and functional outcomes were compared between groups. RESULTS: Overall, 453 patients were treated with RRP and 585 with RALP. On multivariate logistic regression analyses, the type of surgery did not affect surgical margins (p = 0.96) or potency at 12 months (p = 0.7). Patients who had undergone...

  15. Anion-π catalysis.

    Science.gov (United States)

    Zhao, Yingjie; Beuchat, César; Domoto, Yuya; Gajewy, Jadwiga; Wilson, Adam; Mareda, Jiri; Sakai, Naomi; Matile, Stefan

    2014-02-05

    The introduction of new noncovalent interactions to build functional systems is of fundamental importance. We here report experimental and theoretical evidence that anion-π interactions can contribute to catalysis. The Kemp elimination is used as a classical tool to discover conceptually innovative catalysts for reactions with anionic transition states. For anion-π catalysis, a carboxylate base and a solubilizer are covalently attached to the π-acidic surface of naphthalenediimides. On these π-acidic surfaces, transition-state stabilizations up to ΔΔGTS = 31.8 ± 0.4 kJ mol(-1) are found. This value corresponds to a transition-state recognition of KTS = 2.7 ± 0.5 μM and a catalytic proficiency of 3.8 × 10(5) M(-1). Significantly increasing transition-state stabilization with increasing π-acidity of the catalyst, observed for two separate series, demonstrates the existence of "anion-π catalysis." In sharp contrast, increasing π-acidity of the best naphthalenediimide catalysts does not influence the more than 12 000-times weaker substrate recognition (KM = 34.5 ± 1.6 μM). Together with the disappearance of Michaelis-Menten kinetics on the expanded π-surfaces of perylenediimides, this finding supports that contributions from π-π interactions are not very important for anion-π catalysis. The linker between the π-acidic surface and the carboxylate base strongly influences activity. Insufficient length and flexibility cause incompatibility with saturation kinetics. Moreover, preorganizing linkers do not improve catalysis much, suggesting that the ideal positioning of the carboxylate base on the π-acidic surface is achieved by intramolecular anion-π interactions rather than by an optimized structure of the linker. Computational simulations are in excellent agreement with experimental results. They confirm, inter alia, that the stabilization of the anionic transition states (but not the neutral ground states) increases with the π-acidity of the

  16. 野葛异黄酮糖苷的分离纯化及体外清除自由基活性的研究%Free radical scavenging capacities of isoflavonoid glycosides isolated from Pueraria Radix

    Institute of Scientific and Technical Information of China (English)

    杨华; 韩坤; 宛晓春; 方从兵

    2011-01-01

    以野葛的根样为试材,依次通过总黄酮提取、有机溶荆分级分离和柱色谱法进行分离纯化,获得4种异黄酮糖苷组分,依据核磁共振谱和质谱分析结果分别鉴定为葛根素、大豆苷、芒柄花苷和染料木苷.采用1,1-二苯基苦基苯肼(DPPH·)的有机自由基体系和超氧阴离子(O2·-)的无机活性氧自由基体系,对上述4种异黄酮糖苷化舍物的体外清除自由基能力和抗氧化活性进行测定.结果表明,4个异黄酮糖苷组分对DPPH·自由基和O2-·自由基均具有一定的清除活性,清除能力的大小与处理浓度均成正相关关系,对DPPH·自由基的清除效果由高到低依次为染料木苷、大豆苷、葛根素和芒柄花苷,抑制O2·-自由基能力由强到弱依次为葛根素、大豆苷、染料木苷和芒柄花苷.%Crude total isoflavonoids extracted from Pueraria Radix were partitioned by different organic solvents, then isolated and purified by several column chromatographic techniques and four isoflavonoid glycosides were obtained. On basis of the NMR and ESI-MS spectra, these four compounds can be identified as puerarin, daidzin, ononin, and genistin, respectively. Using an organic free radical system of 1, 1-diphenyl-2-picrylhydrazyl (DPPH · ) and an inorganic free radical system of superoxide anion free radical, the free radical scavenging capacities and antioxidant activities of these four isoflavonoid glycosides were examined in vitro. The results showed that all the four isoflavonoid glycosides were discovered to possess the scavenging capacities of the DPPH · free radical and superoxide anion radical. Meanwhile, there was a significantly positive correlation between the two free radical scavenging capacities and the treated concentrations of the four isoflavonoid glycosides. Genistin showed the highest DPPH · free radical scavenging capacity, followed by daidzin and puerarin,and ononin was the lowest among them. However, the

  17. Superoxide DismutasE in Spring Barley Caryopses

    Directory of Open Access Journals (Sweden)

    Natálie Březinová Belcredi

    2016-01-01

    Full Text Available Superoxide dismutase (SOD activity was determined in caryopses of spring barley grown in field trials in 2004–2006. A total set under study included five malting varieties with hulled grain, three waxy hull-less and hulled varieties (of US origin, seven lines formed by crossing of the above given varieties and four hull-less lines of Czech origin. SOD activity was determined by a modified method using a Ransod diagnostic kit (RANDOX. The method employs xanthine and xanthine oxidase to generate superoxide radicals which react with 2-(4-iodophenyl-3-(4-nitrophenol-5-phenyltetrazolium chloride (INT to form a red formazan dye. Statistically significantly higher activity was measured in the variety Nordus (131 U.g−1 d.m. and line ME1 (128 U.g−1 d.m. compared to the other varieties/lines (66–111 U.g−1 d.m.. The line ME1 had significantly higher SOD activity in grain versus its parental varieties Kompakt (83 U.g−1 d.m. and Krona (78 U.g−1 d.m.. The results of this study proved the availability of varieties/lines with a higher SOD content, the antioxidant effect of SOD can improve quality of beer and food made from barley.

  18. Enzyme superoxide dismutase in grain of barley and malt

    Directory of Open Access Journals (Sweden)

    Natálie Belcrediová

    2006-01-01

    Full Text Available The aim of the work was modification of superoxide dismutase enzyme (SOD, EC 1.15.1.1 activity analysis in barley grain and identical malts with using of the Ransod set. This set from company Randox were used for enzyme determination in blood samples. This method employs xanthine and xanthine oxidase to generate superoxide radicals, which react with tetrazolium chloride to form a red formazan dye. SOD is classified as natural antioxidants and enzyme plays a significant role at detoxication of products of molecular oxygen degradation. The largest rate of SOD occurs in embryo of barley grain. Its presence in barley grain and malt thus inhibits rancidity of grain during storage and undesirable beer flavour. The line Wabet x Washonubet (in grain-104,93 and malt 152,42 U/g dry matter and the variety Annabell (104,65 a 147,21 U/g dry matter had the highest activity of SOD in grain and malt of barley while the lowest activity was measured in the line KM 1910 (73,15 a 88,16 U/g dry matter and variety Tolar (74,34 a 96,44 U/g dry matter.

  19. Charge Transfer at the Qo-Site of the Cytochrome bc1 Complex Leads to Superoxide Production

    DEFF Research Database (Denmark)

    Salo, Adrian Bøgh; Husen, Peter; Solov'yov, Ilia A

    2017-01-01

    to influence the normal operation of the bc1 complex and acquire an extra electron, thus becoming superoxide, a biologically toxic free radical. The process is modeled by applying quantum chemical calculations to previously performed classical molecular dynamics simulations. Investigations reveal several...

  20. Changes in the ratio between FPR and FPRL1 triggered superoxide production in human neutrophils-a tool in analysing receptor specific events.

    Science.gov (United States)

    Fu, Huamei; Karlsson, Jennie; Björkman, Lena; Stenfeldt, Anna-Lena; Karlsson, Anna; Bylund, Johan; Dahlgren, Claes

    2008-02-29

    Neutrophils express the G protein-coupled N-formyl peptide receptor (FPR) as well as its closely related homologue, formyl peptide like receptor 1 (FPRL1), and activation of these receptors induce a release of superoxide anions. The magnitude of the responses induced by the two peptide agonists fMLF and WKYMVM, specific for FPR and FPRL1, respectively, was found to be very variable in different neutrophil populations. The ratio between the FPR and FPRL1 triggered respiratory burst was, however, very constant and close to 1. The ratio was changed in neutrophils that were desensitized as well as when the signaling through either of the receptors was inhibited by receptor specific antagonists or by a PIP(2) binding peptide. The FPR/FPRL1 ratio was not changed in primed neutrophils or in differentiated HL-60 cells. We show that the change in the ratio, calculated from the amount of radical release in neutrophils triggered with FPR and FPRL1 specific agonists can be used as a valuable tool to find/identify receptor specific/selective changes mediated by peptides/proteins/drugs, as well as to identify cells from patients or groups of patients that diverge from normal cells in their FPR/FPRL1 triggered functions.

  1. 噻二唑类Schiff碱配合物的合成及其对超氧阴离子自由基的抑制活性%Studies on synthesis and the free radical inhibition rate to superoxide anion of a new schiff base with thiadiazole and their complexes

    Institute of Scientific and Technical Information of China (English)

    王建华; 雷文; 王远亮

    2003-01-01

    用2-氨基-5-巯基-1,3,4-噻二唑与水杨醛及氯乙酸合成了Schiff碱及与Cu(Ⅱ)、Co(Ⅱ)、Zn(Ⅱ)的配合物,并由元素分析、红外光谱、紫外可见光谱和摩尔电导等对其进行了表征.核黄素-蛋氨酸光照法进行的活性实验表明配体及配合物均对超氧离子有一定的抑制效果.

  2. Biological Superoxide In Manganese Oxide Formation

    Science.gov (United States)

    Hansel, C.; Learman, D.; Zeiner, C.; Santelli, C. M.

    2011-12-01

    Manganese (Mn) oxides are among the strongest sorbents and oxidants within the environment, controlling the fate and transport of numerous elements and the degradation of recalcitrant carbon. Both bacteria and fungi mediate the oxidation of Mn(II) to Mn(III/IV) oxides but the genetic and biochemical mechanisms responsible remain poorly understood. Furthermore, the physiological basis for microbial Mn(II) oxidation remains an enigma. We have recently reported that a common marine bacterium (Roseobacter sp. AzwK-3b) oxidizes Mn(II) via reaction with extracellular superoxide (O2-) produced during exponential growth. Here we expand this superoxide-mediated Mn(II) oxidation pathway to fungi, introducing a surprising homology between prokaryotic and eukaryotic metal redox processes. For instance, Stibella aciculosa, a common soil Ascomycete filamentous fungus, precipitates Mn oxides at the base of asexual reproductive structures (synnemata) used to support conidia (Figure 1). This distribution is a consequence of localized production of superoxide (and it's dismutation product hydrogen peroxide, H2O2), leading to abiotic oxidation of Mn(II) by superoxide. Disruption of NADPH oxidase activity using the oxidoreductase inhibitor DPI leads to diminished cell differentiation and subsequent Mn(II) oxidation inhibition. Addition of Cu(II) (an effective superoxide scavenger) leads to a concentration dependent decrease in Mn oxide formation. We predict that due to the widespread production of extracellular superoxide within the fungal and likely bacterial kingdoms, biological superoxide may be an important contributor to the cycling of Mn, as well as other metals (e.g., Hg, Fe). Current and future explorations of the genes and proteins involved in superoxide production and Mn(II) oxidation will ideally lend insight into the physiological and biochemical basis for these processes.

  3. Differential production of superoxide by neuronal mitochondria

    Directory of Open Access Journals (Sweden)

    Levin Leonard A

    2008-01-01

    Full Text Available Abstract Background Mitochondrial DNA (mtDNA mutations, which are present in all mitochondria-containing cells, paradoxically cause tissue-specific disease. For example, Leber's hereditary optic neuropathy (LHON results from one of three point mutations mtDNA coding for complex I components, but is only manifested in retinal ganglion cells (RGCs, a central neuron contained within the retina. Given that RGCs use superoxide for intracellular signaling after axotomy, and that LHON mutations increase superoxide levels in non-RGC transmitochondrial cybrids, we hypothesized that RGCs regulate superoxide levels differently than other neuronal cells. To study this, we compared superoxide production and mitochondrial electron transport chain (METC components in isolated RGC mitochondria to mitochondria isolated from cerebral cortex and neuroblastoma SK-N-AS cells. Results In the presence of the complex I substrate glutamate/malate or the complex II substrate succinate, the rate of superoxide production in RGC-5 cells was significantly lower than cerebral or neuroblastoma cells. Cerebral but not RGC-5 or neuroblastoma cells increased superoxide production in response to the complex I inhibitor rotenone, while neuroblastoma but not cerebral or RGC-5 cells dramatically decreased superoxide production in response to the complex III inhibitor antimycin A. Immunoblotting and real-time quantitative PCR of METC components demonstrated different patterns of expression among the three different sources of neuronal mitochondria. Conclusion RGC-5 mitochondria produce superoxide at significantly lower rates than cerebral and neuroblastoma mitochondria, most likely as a result of differential expression of complex I components. Diversity in METC component expression and function could explain tissue specificity in diseases associated with inherited mtDNA abnormalities.

  4. Monitoring antioxidant defenses and free radical production in space-flight, aviation and railway engine operators, for the prevention and treatment of oxidative stress, immunological impairment, and pre-mature cell aging.

    Science.gov (United States)

    De Luca, C; Deeva, I; Mariani, S; Maiani, G; Stancato, A; Korkina, L

    2009-01-01

    Degenerative diseases, immune impairment, and premature ageing commonly affect professional categories exposed to severe environmental and psychological stress. Among these, cosmonauts routinely experience extreme conditions due to microgravity, space radiation, altered oxygen supply, physical and mental fatigue during training, spaceflight, and post-flight. Long route aviation pilots display elevated oncogenic risk, connected with cosmic radiation overexposure, and high mortality rates for cardiovascular causes. Engine drivers, like pilots, are affected by health consequences of psycho-emotional stress, and burnout syndrome. The free radical (FR)/antioxidant (AO) imbalance is a common feature in all these pathological conditions. To assess the effective relevance of oxidative stress, we analyzed blood and urine reliable markers of FR production and AO defenses in 12 Russian cosmonauts, 55 airline pilots, 63 train engine drivers, and 50 age-matched controls by measuring the following: (a) lipophilic/hydrophilic low-molecular weight AO and AO enzyme activities, (b) nitric oxide, superoxide anion, hydroperoxide production, and (c) urinary catecholamine/serotonine metabolites and lipoperoxidation markers. Cosmonauts showed elevated granulocyte superoxide and nitric oxide production, increased erythrocyte superoxide dismutase activity and glutathione oxidation, and drastically decreased plasma/leucocyte lipophilic AO levels (P monitoring of clinical biochemistry laboratory markers of AO/FR status, to tailor individually specific AO supplementation and diet regimen, and monitor treatment outcomes.

  5. [Effects of hydroxyl radicals on purified angiotensin I converting enzyme].

    Science.gov (United States)

    Michel, B; Nirina, L B; Grima, M; Ingert, C; Coquard, C; Barthelmebs, M; Imbs, J L

    1998-08-01

    Somatic angiotensin-converting enzyme (ACE) is a protein which contains two similar domains (N and C), each possessing a functional active site. The relationship between ACE, its natural substrates and oxygen free radicals is starting to be explored. On one hand, superoxide anions production is induced by angiotensin II and on the other hand, activated polynuclear neutrophils, through free radicals generation, alter endothelial ACE activity. In this study, we examined the impact of hydroxyl radicals (.OH) on purified ACE. .OH were produced using a generator: 2,2'-azo-bis 2-amidinopropane (GRH) provided by Lara-Spiral (Fr). GRH (3 mM), in a time-dependent fashion, inhibited ACE activity. When ACE was co-incubated for 4 h with GRH, its activity decreased by 70%. Addition of dimethylthiourea (DMTU: 0.03 to 1 mM) or mannitol + methionine (20/10 mM), two sets of .OH scavengers, produced a dose-dependent protection on ACE activity. To examine whether oxidation of thiol groups in the ACE molecule could be involved in the action of GRH, the effects of thiol reducing agents: mercaptoethanol and dithiotreitol (DTT) were investigated. These compounds produced a dose-dependent and significant protection; with 100% protection at 0.2 and 0.3 mM for mercaptoethanol and at 0.1 mM for DTT. The hydrolysis of two natural and domain-specific substrates were also explored. The hydrolysis of angiotensin I preferentially cleaved by the C domain was significantly (p GRH [in nmol angio II formed/min/nmol of ACE, n = 4; 35.9 +/- 0.6 (control), 15.5 +/- 2.8 (GRH : 0.3 mM), 15.1 +/- 0.5 (1), 10.9 +/- 0.6 (3)]. The hydrolysis of the hemoregulatory peptide (hp), preferential substrate for the N domain was not affected by GRH at 0.3 mM and inhibited by 28% (not significant) by 1 mM GRH [in nmol ph hydrolized/min/nmol ACE, n = 4; 12.6 +/- 1.9 (control), 14.9 (GRH : 0.3 mM), 8.3 +/- 4.0 (1). These results demonstrated that .OH affect ACE activity and could suggest a privileged impact of GRH on the

  6. Superoxide Enhances the Antitumor Combination of AdMnSOD Plus BCNU in Breast Cancer

    Directory of Open Access Journals (Sweden)

    Joseph J. Cullen

    2010-02-01

    Full Text Available Overexpression of manganese superoxide dismutase (MnSOD can sensitize a variety of cancer cell lines to many anticancer drugs. Recent work has shown that cancer cells can be sensitized to cell killing by raising peroxide levels through increased manganese superoxide dismutase (MnSOD when combined with inhibition of peroxide removal. Here we utilize the mechanistic property of one such anticancer drug, BCNU, which inhibits glutathione reductase (GR, compromising the glutathione peroxidase system thereby inhibiting peroxide removal. The purpose of this study was to determine if anticancer modalities known to produce superoxide radicals can increase the antitumor effect of MnSOD overexpression when combined with BCNU. To enhance MnSOD, an adenoviral construct containing the cDNA for MnSOD (AdMnSOD was introduced into human breast cancer cell line, ZR-75-1. AdMnSOD infection alone did not alter cell killing, however when GR was inhibited with either BCNU or siRNA, cytotoxicity increased. Futhermore, when the AdMnSOD + BCNU treatment was combined with agents that enhance steady-state levels of superoxide (TNF-α, antimycin, adriamycin, photosensitizers, and ionizing radiation, both cell cytotoxicity and intracellular peroxide levels increased. These results suggest that the anticancer effect of AdMnSOD combined with BCNU can be enhanced by agents that increase generation of superoxide.

  7. Superoxide dismutase overexpression protects against glucocorticoid-induced depressive-like behavioral phenotypes in mice.

    Science.gov (United States)

    Uchihara, Yuki; Tanaka, Ken-ichiro; Asano, Teita; Tamura, Fumiya; Mizushima, Tohru

    2016-01-22

    In the stress response, activation of the hypothalamic-pituitary-adrenal axis, and particularly the release of glucocorticoids, plays a critical role. However, dysregulation of this system and sustained high plasma levels of glucocorticoids can result in depression. Recent studies have suggested the involvement of reactive oxygen species (ROS), such as superoxide anion, in depression. However, direct evidence for a role of ROS in the pathogenesis of this disorder is lacking. In this study, using transgenic mice expressing human Cu/Zn-superoxide dismutase (SOD1), an enzyme that catalyzes the dismutation of superoxide anions, we examined the effect of SOD1 overexpression on depressive-like behavioral phenotypes in mice. Depressive-like behaviors were induced by daily subcutaneous administration of the glucocorticoid corticosterone for 4 weeks, and was monitored with the social interaction test, the sucrose preference test and the forced swim test. These tests revealed that transgenic mice overexpressing SOD1 are more resistant to glucocorticoid-induced depressive-like behavioral disorders than wild-type animals. Furthermore, compared with wild-type mice, transgenic mice showed a reduction in the number of 8-hydroxy-2'-deoxyguanosine (a marker of oxidative stress)-positive cells in the hippocampal CA3 region following corticosterone administration. These results suggest that overexpression of SOD1 protects mice against glucocorticoid-induced depressive-like behaviors by decreasing cellular ROS levels.

  8. Magnetic Resonance Imaging of Mitochondrial Dysfunction and Metabolic Activity, Accompanied by Overproduction of Superoxide.

    Science.gov (United States)

    Bakalova, Rumiana; Georgieva, Ekaterina; Ivanova, Donika; Zhelev, Zhivko; Aoki, Ichio; Saga, Tsuneo

    2015-12-16

    This study shows that a mitochondria-penetrating nitroxide probe (mito-TEMPO) allows detection of superoxide and visualization of mitochondrial dysfunction in living cells due to the effect of T1 shortening in MRI. Mitochondrial dysfunction was induced by treatment of cells with rotenone and 2-methoxyestradiol (2-ME/Rot). The MRI measurements were performed on 7T MRI. The 2-ME/Rot-treated cells were characterized by overproduction of superoxide, which was confirmed by a conventional dihydroethidium test. In the presence of mito-TEMPO, the intensity of MRI signal in 2-ME/Rot-treated cells was ∼30-40% higher, in comparison with that in untreated cells or culture media. In model (cell-free) systems, we observed that superoxide, but not hydrogen peroxide, increased the intensity of T1-weighted MRI signal of mito-TEMPO. Moreover, the superoxide restores the T1-weighted MRI contrast of mito-TEMPOH, a noncontrast (diamagnetic) analogue of mito-TEMPO. This was also confirmed by using EPR spectroscopy. The results demonstrate that superoxide radical is involved in the enhancement of T1-weighted MRI contrast in living cells, in the absence and presence of mito-TEMPO. This report gives a direction for discovering new opportunities for functional MRI, for detection of metabolic activity, accompanied by overproduction of superoxide, as well as by disturbance of the balance between superoxide and hydrogen peroxide, a very important approach to clarify the fine molecular mechanisms in the regulation of many pathologies. The visualization of mitochondrial activity in real-time can be crucial to clarify the molecular mechanism of the functional MRI in its commonly accepted definition, as a method for detection of neurovascular coupling.

  9. Potentiometric anion selective sensors

    NARCIS (Netherlands)

    Antonisse, Martijn M.G.; Reinhoudt, David N.

    1999-01-01

    In comparison with selective receptors (and sensors) for cationic species, work on the selective complexation and detection of anions is of more recent date. There are three important components for a sensor, a transducer element, a membrane material that separates the transducer element and the aqu

  10. Magnetoreception through Cryptochrome may involve superoxide

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Schulten, Klaus

    2009-01-01

    is still not understood. One theory for magnetoreception in birds invokes the so-called radical-pair model. This mechanism involves a pair of reactive radicals, whose chemical fate can be influenced by the orientation with respect to the magnetic field of the Earth through Zeeman and hyperfine interactions....... The fact that the geomagnetic field is weak, i.e., ~0.5 G, puts a severe constraint on the radical pair that can establish the magnetic compass sense. For a noticeable change of the reaction yield in a redirected geomagnetic field, the hyperfine interaction has to be as weak as the Earth field Zeeman...... interaction, i.e., unusually weak for an organic compound. Such weak hyperfine interaction can be achieved if one of the radicals is completely devoid of this interaction as realized in a radical pair containing an oxygen molecule as one of the radicals. Accordingly, we investigate here a possible radical...

  11. Hyperglycemic switch from mitochondrial nitric oxide to superoxide production in endothelial cells.

    Science.gov (United States)

    Brodsky, Sergey V; Gao, Shujuan; Li, Hong; Goligorsky, Michael S

    2002-11-01

    The accumulated ultrastructural and biochemical evidence is highly suggestive of the existence of mitochondrial nitric oxide (NO) synthase (mtNOS), where local production of NO regulates the electron transport along the respiratory chain. Here, the functional competence of mtNOS in situ in a living cell was examined using an intravital fluorescent NO indicator, 4,5-diaminofluorescein, employing a new procedure for loading it into the mitochondria to demonstrate local NO generation in undisrupted endothelial cells and in isolated mitochondria as well as in human embryonic kidney cells stably expressing endothelial NOS. With the use of this approach, we showed that endothelial cells incubated in the presence of high concentration of D-glucose (but not L-glucose) are characterized by the reduced NO synthetic function of mitochondria despite the unaltered abundance of the enzyme. In parallel, mitochondrial generation of superoxide was augmented in endothelial cells incubated in the presence of a high concentration of D-glucose. Both the NO generation and superoxide production in hyperglycemic environment could be restored to control levels by treating cells with a cell-permeable superoxide dismutase mimetic. In addition, enhanced mitochondrial superoxide production could be suppressed with an inhibitor of NOS in stimulated endothelial cells. In conclusion, the data 1) provide direct evidence of mitochondrial NO production in endothelial cells, 2) demonstrate its suppression and enhanced superoxide generation in hyperglycemic environment, and 3) provide evidence that "uncoupled" mtNOS represents an important source of superoxide anions in endothelial cells incubated in high glucose-containing medium.

  12. Perspective: Electrospray photoelectron spectroscopy: From multiply-charged anions to ultracold anions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lai-Sheng, E-mail: Lai-Sheng-Wang@brown.edu [Department of Chemistry, Brown University, Providence, Rhode Island 02912 (United States)

    2015-07-28

    Electrospray ionization (ESI) has become an essential tool in chemical physics and physical chemistry for the production of novel molecular ions from solution samples for a variety of spectroscopic experiments. ESI was used to produce free multiply-charged anions (MCAs) for photoelectron spectroscopy (PES) in the late 1990 s, allowing many interesting properties of this class of exotic species to be investigated. Free MCAs are characterized by strong intramolecular Coulomb repulsions, which create a repulsive Coulomb barrier (RCB) for electron emission. The RCB endows many fascinating properties to MCAs, giving rise to meta-stable anions with negative electron binding energies. Recent development in the PES of MCAs includes photoelectron imaging to examine the influence of the RCB on the electron emission dynamics, pump-probe experiments to examine electron tunneling through the RCB, and isomer-specific experiments by coupling PES with ion mobility for biological MCAs. The development of a cryogenically cooled Paul trap has led to much better resolved PE spectra for MCAs by creating vibrationally cold anions from the room temperature ESI source. Recent advances in coupling the cryogenic Paul trap with PE imaging have allowed high-resolution PE spectra to be obtained for singly charged anions produced by ESI. In particular, the observation of dipole-bound excited states has made it possible to conduct vibrational autodetachment spectroscopy and resonant PES, which yield much richer vibrational spectroscopic information for dipolar free radicals than traditional PES.

  13. High-Content Imaging Assays for Identifying Compounds that Generate Superoxide and Impair Mitochondrial Membrane Potential in Adherent Eukaryotic Cells.

    Science.gov (United States)

    Billis, Puja; Will, Yvonne; Nadanaciva, Sashi

    2014-02-19

    Reactive oxygen species (ROS) are constantly produced in cells as a result of aerobic metabolism. When there is an excessive production of ROS and the cell's antioxidant defenses are overwhelmed, oxidative stress occurs. The superoxide anion is a type of ROS that is produced primarily in mitochondria but is also generated in other regions of the cell including peroxisomes, endoplasmic reticulum, plasma membrane, and cytosol. Here, a high-content imaging assay using the dye dihydroethidium is described for identifying compounds that generate superoxide in eukaryotic cells. A high-content imaging assay using the fluorescent dye tetramethylrhodamine methyl ester is also described to identify compounds that impair mitochondrial membrane potential in eukaryotic cells. The purpose of performing both assays is to identify compounds that (1) generate superoxide at lower concentrations than they impair mitochondrial membrane potential, (2) impair mitochondrial membrane potential at lower concentrations than they generate superoxide, (3) generate superoxide and impair mitochondrial function at similar concentrations, and (4) do not generate superoxide or impair mitochondrial membrane potential during the duration of the assays.

  14. Signaling and Damaging Functions of Free Radicals in Aging-Free Radical Theory, Hormesis, and TOR.

    Science.gov (United States)

    Afanas'ev, Igor

    2010-10-01

    Harman's Free Radical Theory of Aging has been considered as a major theory of aging for more than 50 years. In 1956 Dr. Harman proposed that the accumulation of free radicals with the age causes the damage of biomolecules by these reactive species and the development of pathological disorders resulting in cell senescence and organismal aging. His hypothesis was supported by numerous experimental studies demonstrated an increase in free radical levels in cells and living organisms with aging. In subsequent years important discoveries of new physiological free radicals superoxide and nitric oxide have been made that led to understanding of other important functions of free radicals. It has been shown that superoxide and nitric oxide together with their diamagnetic reaction products hydrogen peroxide and peroxynitrite (all are now named reactive oxygen and nitrogen species, ROS and RNS) function as signaling species in many physiological enzymatic/gene processes. Furthermore, the disturbance of ROS and RNS physiological signaling can be an origin of various pathologies and aging. These discoveries demanded to widen original free radical theory of aging and to consider the damaging ROS signaling as an important, maybe major route to cell senescence and organismal aging. However, some experimental findings such as the extension of lifespan by calorie restriction of yeast, flies, worms, and mice, and favorable effects of physical exercises stimulated criticism of free radical theory because the expansion of lifespan accompanied in some cases by increasing oxidative stress. On these grounds such theories as Hormesis and Target of rapamycin (mTOR) theories refute the role of ROS and oxidative stress in aging. Accordingly, a major purpose of this review to show that ROS signaling is probably the most important enzyme/gene pathway responsible for the development of cell senescence and organismal aging and that ROS signaling might be considered as further development of free

  15. Total anesthesia, rats brain surgery, nitric oxide (NO) and free radicals

    OpenAIRE

    Jelenković Ankica V.; Jovanović Marina; Ninković Milica; Maksimović M.; Bošković Bogdan

    2005-01-01

    It is expected that clinical recovery after surgically induced brain trauma is followed by molecular and biochemical restitution. Seven days after surgery, we investigated whether the plastic cannula implanted in the left brain ventricle of adult Wistar rats (n = 6-7), performed in pentobarbital anesthesia, could influence oxidative stress elements (superoxide anion and lipid peroxidation), as well as the antioxidative system (superoxide dismuthase-SOD). Also, we investigated whether nitric o...

  16. Effect of Korea red ginseng on cerebral blood flow and superoxide production

    Institute of Scientific and Technical Information of China (English)

    Cuk Seong KIM; Jin Bong PARK; Kwang-Jin KIM; Seok Jong CHANG; Sung-Woo RYOO; Byeong Hwa JEON

    2002-01-01

    AIM: To investigate the effects of Korea red ginseng (KRG) on the cerebral perfusion rate in the rats and the generation of superoxide anion in the endothelial cells. METHODS: The cerebral perfusion rate was measured using laser-doppler flowmetry before and after the administration of crude saponin (CS) and saponin-free fraction (SFF) of KRG in the anesthetized rats. The superoxide generation was measured by the method based on lucigeninenhanced chemiluminescence in the cultured endothelial cells. RESULTS: The relative cerebral perfusion rate (rCBF) was significantly increased by the intraperitoneal injection of CS (100 mg/kg) in the rats, but SFF had no effect on the rCBF. Chronic treatment with CS for 7 d significantly inhibited the decrease of forebrain cerebral blood flow induced by clamping both carotid arteries in the rats. Furthermore, CS (0.1 g/L) significantly suppressed NADPH-induced superoxide generation in the human umbilical vein endothelial cells (P<0.01).CONCLUSION: The present study demonstrated that crude saponin fraction of KRG enhanced cerebral blood flow in rats. Furthermore, crude saponin fraction of KRG abrogated the NADPH-driven superoxide generation in endothelial cells.

  17. Tobacco Smoke: Involvement of Reactive Oxygen Species and Stable Free Radicals in Mechanisms of Oxidative Damage, Carcinogenesis and Synergistic Effects with Other Respirable Particles

    Directory of Open Access Journals (Sweden)

    Konstantinos Fiotakis

    2009-02-01

    Full Text Available Tobacco smoke contains many toxic, carcinogenic and mutagenic chemicals, as well as stable and unstable free radicals and reactive oxygen species (ROS in the particulate and the gas phase with the potential for biological oxidative damage. Epidemiological evidence established that smoking is one of the most important extrinsic factor of premature morbidity and mortality. The objective of this study was to investigate oxidative and carcinogenic mechanisms of tobacco and synergistic action with other respirable particles in the respiratory system of smokers. Electron Paramagnetic Resonance (EPR and spin- trapping techniques were used to study stable free radicals in the cigarette tar, and unstable superoxide anion (O2·- and hydroxyl (HO· radicals in the smoke Results showed that the semiquinone radical system has the potential for redox recycling and oxidative action. Further, results proved that aqueous cigarette tar (ACT solutions can generate adducts with DNA nucleobases, particularly the mutagenic 8-hydroxy-2’-deoxyguanosine (a biomarker for carcinogenesis.Also, we observed synergistic effects in the generation of HO·, through the Fenton reaction, with environmental respirable particles (asbestos fibres, coal dust, etc. and ambient particulate matter (PM, such as PM10, PM2.5 and diesel exhaust particles (DEP. The highest synergistic effects was observed with the asbestos fibres (freshly grounded, PM2.5 and DEP. Finally, we discuss results from our previous study of conventional cellulose acetate filters and “bio-filters” with hemoglobin impregnated activated carbon, which showed that these filters do not substantially alter the free radical content of smoke in the particulate and in the gaseous phase.

  18. Process for the preparation of calcium superoxide

    Science.gov (United States)

    Ballou, E. V.; Wood, P. C.; Wydeven, T. J.; Spitze, L. A. (Inventor)

    1978-01-01

    Calcium superoxide is prepared in high yields by spreading a quantity of calcium peroxide diperoxyhydrate on the surface of a container, positioning said container in a vacuum chamber on a support structure through which a coolant fluid can be circulated, partially evacuating said vacuum chamber, allowing the temperature of the diperoxyhydrate to reach the range of about 0 to about 40 C; maintaining the temperature selected for a period of time sufficient to complete the disproproriation of the diperoxyhydrate to calcium superoxide, calcium hydroxide, oxygen, and water; constantly and systematically removing the water as it is formed by sweeping the reacting material with a current of dry inert gas and/or by condensation of said water on a cold surface; backfilling the chamber with a dry inert gas; and finally, recovering the calcium superoxide produced.

  19. Radical Scavenging Effects of Different Veronica species

    Directory of Open Access Journals (Sweden)

    Ummuhan Şebnem 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 μg/ml and V. officinalis against DPPH and NO radicals (IC50 40.93 μg/ml, 570.33 μg/ml, respectively .

  20. 蛋清的蛋白酶解物清除自由基能力的研究%STUDY ON FREE RADICAL SCAVENGING ACTIVITY OF PROTEINASE HYDROLYSATES FROM EGG WHITE

    Institute of Scientific and Technical Information of China (English)

    陈晨; 迟玉杰; 刘丽

    2009-01-01

    目的 研究胃蛋白酶、胰蛋白酶、木瓜蛋白酶、中性蛋白酶及Alcalase碱性蛋白酶对蛋清蛋白的水解效果以及其酶解物对自由基的清除能力.方法 采用茚三酮法分析五种蛋白酶对蛋清蛋白的水解效果;通过Fenton体系和邻苯三酚自氧化体系测定五种蛋白酶水解产物对羟自由基及超氧阴离子的清除能力.结果 五种蛋白酶在其最适反应条件下,水解度大小依次为:alcalase碱性蛋白酶>胰蛋白酶>木瓜蛋白酶>中性蛋白酶>胃蛋白酶;羟自由基清除能力强弱依次为:木瓜蛋白酶>alcalase碱性蛋白酶>胰蛋白酶>中性蛋白酶>胃蛋白酶;超氧阴离子清除能力强弱依次为:木瓜蛋白酶>alcalase碱性蛋白酶>中性蛋白酶>胃蛋白酶>胰蛋白酶.木瓜蛋白酶水解3h的产物对两种自由基清除能力最强,对羟自由基的清除率为65.63%,对超氧阴离子的清除率为38.40%.结论 蛋清的蛋白酶解物具有清除羟自由基及超氧阴离子的能力,且对羟自由基的清除能力大于超氧阴离子.%Objective To determine the degree of hydrolysis (DH) and free radical scavenging activity of the hydrolysates of egg white protein (EWPHs) with pepsin, trypsin, papain, neutrase and Alcalase. Method The degree of hydrolysis of EWPH was measured by ninhydrin colorimetric method. The hydroxyl radical and superoxide anion scavenging activity was detected by the methods related to pyrogallol autoxidation and Fenton system. Results Under the optimal conditions the sequence of enzyme hydrolysis capacity was: alcalase>typsin>papain>neutrase>pepsin. The order of hydroxyl radical scavenging activity was: papain>alcalase>trypsin>neutrase>pepsin and the order of superoxide radical scavenging activity was: papain>alcalase>neutrase>pepsin>trypsin. The EWPHs with papain for 3h displayed the strongest radical scavenging activity. The values of hydroxyl radical and superoxide free radical scavenging activity were 65.63% and 38

  1. Superoxide Complex [W4O12(O2')]:A Theoretical Study

    Institute of Scientific and Technical Information of China (English)

    WANG Bin; ZHANG Xian-Hui; HUANG Xin; ZHANG Yong-Fan

    2008-01-01

    Extensive DFT calculations are performed to optimize the geometric structures of O-rich tungsten oxide clusters, to simulate the PES spectra, and to analyze the chemical bonding. The ground-state structure of W4O14- is best considered as W4O12(O2-), containing a side-on bound superoxide ligand. The current study indicates that the extra electron in W4O12- is capable of activating dioxygen by non-dissociative electron transfer (W 5d→O2 π*), and the anionic clusters can be viewed as models for reduced defect sites on tungsten oxide surfaces for the chemisorption of O2.

  2. Superoxide dismutase versus ferricytochrome C: determining rate constants for the spin trapping of superoxide by cyclic nitrones.

    Science.gov (United States)

    Weaver, John; Tsai, Pei; Pou, Sovitj; Rosen, Gerald M

    2004-11-26

    Given that spin trapping/electron paramagnetic resonance (EPR) spectroscopy has become the primary technique to identify important biologically generated free radicals, such as superoxide (O(2)(*-)), in vitro and in vivo models, evaluation of the efficiency of specific spin traps to identify this free radical is paramount. Recently, a family of ester-containing nitrones has been prepared, which appears to have distinct advantages for spin trapping O(2)(*-) compared to the well-studied spin traps 5,5-dimethyl-1-pyrroline N-oxide 1 and 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline N-oxide 2. An important determinant in the selection of a spin trap is the rate constant (k(app)) for its reaction with O(2)(*-), and several different methods have been employed in estimating this k(app). In this paper, the two most frequently used scavengers of O(2)(*-), ferricytochrome c and Cu/Zn-SOD, were evaluated as competitive inhibitors for spin trapping this free radical. Data presented herein demonstrate that SOD is the preferred compound when determining the k(app) for the reaction of O(2)(*-) with spin traps. Using this model, the k(app) for the reaction of nitrone 1, 5-tert-butoxycarbonyl-5-methyl-1-pyrroline N-oxide 3, and 5-methoxycarbonyl-5-methyl-1-pyrroline N-oxide 4 with O(2)(*)(-) was estimated to be 24.6 +/- 3.1, 73.0 +/- 12, and 89.4 +/- 1.0 M(-1) s(-1) at pH 7.0, respectively. Several other comparative studies between known spin traps were also undertaken.

  3. Neural stem cells genetically modified to overexpress cu/zn-superoxide dismutase enhance amelioration of ischemic stroke in mice.

    Science.gov (United States)

    Sakata, Hiroyuki; Niizuma, Kuniyasu; Wakai, Takuma; Narasimhan, Purnima; Maier, Carolina M; Chan, Pak H

    2012-09-01

    The harsh host brain microenvironment caused by production of reactive oxygen species after ischemic reperfusion injury offers a significant challenge to survival of transplanted neural stem cells (NSCs) after ischemic stroke. Copper/zinc-superoxide dismutase (SOD1) is a specific antioxidant enzyme that counteracts superoxide anions. We have investigated whether genetic manipulation to overexpress SOD1 enhances survival of grafted stem cells and accelerates amelioration of ischemic stroke. NSCs genetically modified to overexpress or downexpress SOD1 were administered intracerebrally 2 days after transient middle cerebral artery occlusion. Histological and behavioral tests were examined from Days 0 to 28 after stroke. Overexpression of SOD1 suppressed production of superoxide anions after ischemic reperfusion injury and reduced NSC death after transplantation. In contrast, downexpression of SOD1 promoted superoxide generation and increased oxidative stress-mediated NSC death. Transplantation of SOD1-overexpressing NSCs enhanced angiogenesis in the ischemic border zone through upregulation of vascular endothelial growth factor. Moreover, grafted SOD1-overexpressing NSCs reduced infarct size and improved behavioral performance compared with NSCs that were not genetically modified. Our findings reveal a strong involvement of SOD1 expression in NSC survival after ischemic reperfusion injury. We propose that conferring antioxidant properties on NSCs by genetic manipulation of SOD1 is a potential approach for enhancing the effectiveness of cell transplantation therapy in ischemic stroke.

  4. Ignorance Radicalized

    Directory of Open Access Journals (Sweden)

    Gergo Somodi

    2009-12-01

    Full Text Available The aim of this paper is twofold. I criticize Michael Devitt's linguistic---as opposed to Chomsky's psychological---conception of linguistics on the one hand, and I modify his related view on linguistic intuitions on the other. I argue that Devitt's argument for the linguistic conception is in conflict with one of the main theses of that very conception, according to which linguistics should be about physical sentence tokens of a given language rather than about the psychologically real competence of native speakers. The basis of this conflict is that Devitt's view on language, as I will show, inherits too much from the criticized Chomskian view. This is also the basis of Devitt's strange claim that it is the linguist, and not the ordinary speaker, whose linguistic intuition should have an evidential role in linguistics. I will argue for the opposite by sketching a view on language that is more appropriate to the linguistic conception. That is, in criticizing Devitt, I am not defending the Chomskian approach. My aim is to radicalize Devitt's claims.

  5. Propofol attenuates high glucose-induced superoxide anion accumulation in human umbilical vein endothelial cells.

    Science.gov (United States)

    Wang, Jiaqiang; Jiang, Hui; Wang, Jing; Zhao, Yanjun; Zhu, Yun; Zhu, Minmin

    2016-12-01

    Perioperative hyperglycemia is a common clinical metabolic disorder. Hyperglycemia could induce endothelial apoptosis, dysfunction, and inflammation, resulting in endothelial injury. Propofol is a widely used anesthetic drug in clinical settings. Our previous studies indicated that propofol attenuated high glucose-induced endothelial apoptosis, dysfunction, and inflammation via inhibiting reactive oxygen species (ROS) accumulation. However, the mechanisms by which propofol reduces high glucose-induced endothelial ROS accumulation are still obscure. In this study, we examined how propofol attenuates high glucose-induced endothelial ROS accumulation. Compared with 5 mm glucose treatment, 15 mm glucose upregulated the expression of pin-1, phosphatase A2 (PP2A), p66(shc) and mitochondrial p66(shc) expression, increased p66(shc) -Ser(36) phosphorylation, and O2·- accumulation. More importantly, although propofol had no effect on 15 mm glucose-induced p66(shc) -Ser(36) phosphorylation and pin-1 expression, propofol could downregulated PP2A expression and p66(shc) expression in whole-cell and mitochondrion, resulting in the reduction of O2·- accumulation. Moreover, we demonstrated that the antioxidative effect of propofol was similar to that of calyculin A, an inhibitor of PP2A. In contrast, FTY720, an activator of PP2A, antagonized the effect of propofol. Our data indicated that the antioxidative effect of propofol was achieved by downregulating PP2A expression, resulting in the inhibition of p66(shc) -Ser(36) dephosphorylation and mitochondrial p66(shc) expression. © 2016 Société Française de Pharmacologie et de Thérapeutique.

  6. Microsomal superoxide anion production and NADPH-oxidation in a series of 22 aziridinylbenzoquinones

    NARCIS (Netherlands)

    Prins, Bram; Koster, Andries Sj.; Verboom, Willem; Reinhoudt, David N.

    1989-01-01

    Several 2,5-bis(1-aziridinyl)-1,4-benzoquinones (BABQs) can be activated to alkylating species by reduction of the quinone moiety. On the other hand, cytotoxicity of these compounds can be induced by redox cycling. A series of BABQs and their methylated analogues (BMABQs) with different substituents

  7. Effect of beta2-adrenergic agonists on eosinophil adhesion, superoxide anion generation, and degranulation

    Directory of Open Access Journals (Sweden)

    Toru Noguchi

    2015-09-01

    Conclusions: These findings suggest that formoterol, but not salbutamol, suppresses eosinophil functions enhanced by IL-5, LTD4, or IP-10. As these factors are involved in the development of asthma exacerbation, our results strongly support the hypothesis that administration of formoterol is a novel strategy for treating asthma exacerbation.

  8. Terrorism, radicalization, and de-radicalization

    NARCIS (Netherlands)

    Doosje, B.; Moghaddam, F.M.; Kruglanski, A.W.; de Wolf, A.; Mann, L.; Feddes, A.R.

    2016-01-01

    In this article, we review the literature and present a model of radicalization and de-radicalization. In this model, we distinguish three phases in radicalization: (1) a sensitivity phase, (2) a group membership phase and (3) an action phase. We describe the micro-level, meso-level and macro-level

  9. Effect of anions on the electrochemistry of zinc tetraphenylporphyrin

    Energy Technology Data Exchange (ETDEWEB)

    Seely, G.R.; Gust, D.; Moore, T.A.; Moore, A.L. (Arizona State Univ., Tempe, AZ (United States))

    1994-10-13

    Accurate measurements of porphyrin redox potentials are essential for the prediction and rationalization of the rates of electron transfer reactions involving these biologically important electron-donating and accepting chromophores. The present work describes a survey of redox potentials of zinc tetraphenylporphyrin obtained by cyclic voltammetry in dichloromethane, with tetrabutylammonium salts containing a variety of anions as electrolytes. Of the anions tested, hexafluorophosphate appears to have the least ability to ligate the metal, so that potentials measured in its presence as electrolyte should most closely approach those of the unligated porphyrin. With perchlorate electrolyte, the potential for one-electron oxidation is approximately 80 mV lower, enough to affect the interpretation of photochemical electron transfer rates. In general, anions bind much more strongly to the cation radical than to zinc tetraphenylporphyrin itself. The use of reference redox systems based on thymoquinone and ferrocene carboxylate enabled comparison of potentials measured with different electrolytes. 30 refs., 2 tabs.

  10. Manganese superoxide dismutase and breast cancer recurrence

    DEFF Research Database (Denmark)

    Cronin-Fenton, Deirdre P; Christensen, Mariann; Lash, Timothy L

    2014-01-01

    BACKGROUND: Manganese superoxide dismutase (MnSOD) inhibits oxidative damage and cancer therapy effectiveness. A polymorphism in its encoding gene (SOD2: Val16Ala rs4880) may confer poorer breast cancer survival, but data are inconsistent. We examined the association of SOD2 genotype and breast...

  11. Superoxide reductase from Desulfoarculus baarsii: reaction mechanism and role of glutamate 47 and lysine 48 in catalysis

    CERN Document Server

    Lombard, M; Touati, D; Fontecave, M; Nivière, V

    2015-01-01

    Superoxide reductase (SOR) is a small metalloenzyme that catalyzes reduction of O(2)(*)(-) to H(2)O(2) and thus provides an antioxidant mechanism against superoxide radicals. Its active site contains an unusual mononuclear ferrous center, which is very efficient during electron transfer to O(2)(*)(-) [Lombard, M., Fontecave, M., Touati, D., and Nivi{\\`e}re, V. (2000) J. Biol. Chem. 275, 115-121]. The reaction of the enzyme from Desulfoarculus baarsii with superoxide was studied by pulse radiolysis methods. The first step is an extremely fast bimolecular reaction of superoxide reductase with superoxide, with a rate constant of (1.1 +/- 0.3) x 10(9) M(-1) s(-1). A first intermediate is formed which is converted to a second one at a much slower rate constant of 500 +/- 50 s(-1). Decay of the second intermediate occurs with a rate constant of 25 +/- 5 s(-1). These intermediates are suggested to be iron-superoxide and iron-peroxide species. Furthermore, the role of glutamate 47 and lysine 48, which are the closest...

  12. Oxygen radical induced fluorescence in proteins; identification of the fluorescent tryptophan metabolite, N-formyl kynurenine, as a biological index of radical damage.

    Science.gov (United States)

    Griffiths, H R; Lunec, J; Blake, D R

    1992-06-01

    The effect of oxygen derived free radicals (OFR) on aromatic and sulphur containing amino acids has been investigated, both in their free form and within protein backbones. Aerated amino acids and proteins in solution were exposed to three discrete OFR generating systems; (1) gamma radiation in the presence or absence of formate (2) photolysis by UV light at 254 and 366 nm, and (3) site specific modification by H2O2 in the presence of CuII ions.A sensitive reverse-phase HPLC technique with dual detection systems (UV absorbance and fluorescence monitoring) was developed to analyse the products of amino acid oxidation. OFR denatured amino acids were chromatographed by this procedure, and all radical species generated, with the exception of the superoxide anion, resulted in the formation of identifiable fluorescent metabolites of tryptophan, kynurenines. The identity of peaks was confimed by spiking with authentic material and scanning absorption spectroscopy. After complete proteolytic hydrolysis, OFR treated proteins were also analysed by this technique; again the dose dependent production of kynurenines was detected in IgG,γ lens crystallins and albumin. Bityrosine was not detected in any of the proteins studied using this procedure, however, several novel unidentified fluorophores were detected in proteolytic hydrolysates, possibly the product of two different amino acid radicals.Immunoglobulin G isolated from the sera of normals and rheumatoid arthritis (RA) patients was examined for the presence of one specific tryptophan metabolite, N-formyl kynurenine. Significantly elevated levels of this metabolite were detected in rheumatoid sera, suggesting increased OFR activity in RA.These results have demonstrated firstly, that specific oxidised products of amino acids are retained in the protein backbone after exposure to OFR generating systems. Secondly, in aerated solution, oxidised tryptophan residues confer the major new visible fluorescence in non-haem proteins

  13. Calorimetric Study of Thermal Denaturation of Superoxide Dismutase

    Institute of Scientific and Technical Information of China (English)

    王邦宁; 谈夫

    1994-01-01

    The thermal denaturation of superoxide dismutase (SOD) from bovine erythrocytes was studied at various pH values of different buffers and at various concentrations of solutions of two neutral salts by differential scanning calorimetry. The experiments performed indicate that the PIPES is a buffer non-coordinating with the SOD, and that the binding of the anions studied influences more or less the thermal denaturation of SOD, but the effect on the oxidation form of SOD is more apparent. A new conformer of SOD with lower thermostability was discovered by the experiments performed in different buffers at certain pH values higher than the isoelectric point of SOD, or at higher concentrations of neutral salt solutions. The new conformer may be converted irreversibly into the usual conformer with high thermostability during heating. Based on the thermodynamic parameters obtained in distilled water and by thermodynamic analysis using the Ooi’s model, it is revealed that the large enthalpy △Hdc contributed by

  14. Molecular cloning and biochemical characterization of iron superoxide dismutase from the rodent malaria parasite Plasmodium vinckei.

    Science.gov (United States)

    Prakash, Kirtika; Goyal, Manish; Soni, Awakash; Siddiqui, Arif Jamal; Bhardwaj, Jyoti; Puri, Sunil K

    2014-12-01

    Plasmodium parasite utilizes superoxide dismutase family proteins to limit the toxicity of reactive oxygen species, such as produced through hemoglobin degradation. These proteins play an important role in parasite survival during intra-erythrocytic phase. We have identified, and biochemically characterized a putative iron dependent superoxide dismutase from rodent malaria parasite Plasmodium vinckei (PvSOD1). The recombinant PvSOD1 protein was purified to homogeneity through a combination of affinity and gel filtration chromatography. Crosslinking, Native-PAGE and FPLC gel filtration analyses documented that PvSOD1 exists as a dimer in solution, a common feature shared by other Fe-SODs. PvSOD1 is cytosolic in localization and its expression is comparatively higher during trophozoite as compared to that of ring and schizont stages. Enzymatic activity of recombinant PvSOD1 was validated using conventional zymogram analyses and xanthine-xanthine oxidase system. Under optimal conditions, PvSOD1 was highly active and catalyzed the dismutation of superoxide radicals. Furthermore, PvSOD1 showed activity over a broad range of pH and temperature. Inhibition studies suggested that PvSOD1 was inactivated by hydrogen peroxide, and peroxynitrite, but not by cyanide and azide. Since, PvSOD1 plays a central role in oxidative defense mechanism, therefore, characterization of PvSOD1 will be exploited in the screening of new superoxide dismutase inhibitors for their antimalarial activity. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  15. Resonant spectra of quadrupolar anions

    CERN Document Server

    Fossez, K; Nazarewicz, W; Michel, N; Garrett, W R; Płoszajczak, M

    2016-01-01

    In quadrupole-bound anions, an extra electron is attached at a sufficiently large quadrupole moment of a neutral molecule, which is lacking a permanent dipole moment. The nature of the bound states and low-lying resonances of such anions is of interest for understanding the threshold behavior of open quantum systems in general. In this work, we investigate the properties of quadrupolar anions as extreme halo systems, the formation of rotational bands, and the transition from a subcritical to supercritical electric quadrupole moment. We solve the electron-plus-molecule problem using a non-adiabatic coupled-channel formalism by employing the Berggren ensemble, which explicitly contains bound states, narrow resonances, and the scattering continuum. We demonstrate that binding energies and radii of quadrupolar anions strictly follow the scaling laws for two-body halo systems. Contrary to the case of dipolar anions, ground-state band of quadrupolar anions smoothly extend into the continuum, and many rotational ban...

  16. LC-MS/MS Analysis Unravels Deep Oxidation of Manganese Superoxide Dismutase in Kidney Cancer

    Science.gov (United States)

    Zhao, Zuohui; Azadzoi, Kazem M.; Choi, Han-Pil; Jing, Ruirui; Lu, Xin; Li, Cuiling; Wang, Fengqin; Lu, Jiaju; Yang, Jing-Hua

    2017-01-01

    Manganese superoxide dismutase (MNSOD) is one of the major scavengers of reactive oxygen species (ROS) in mitochondria with pivotal regulatory role in ischemic disorders, inflammation and cancer. Here we report oxidative modification of MNSOD in human renal cell carcinoma (RCC) by the shotgun method using data-dependent liquid chromatography tandem mass spectrometry (LC-MS/MS). While 5816 and 5571 proteins were identified in cancer and adjacent tissues, respectively, 208 proteins were found to be up- or down-regulated (p kidney cancer due to modifications. Thus, LC-MS/MS analysis revealed multiple oxidative modifications of MNSOD at different amino acid residues that might mediate the regulation of the superoxide radicals, mitochondrial ROS scavenging and MNSOD activity in kidney cancer. PMID:28165386

  17. Manganese superoxide dismutase, but not CuZn superoxide dismutase, is highly expressed in the granulomas of pulmonary sarcoidosis and extrinsic allergic alveolitis.

    Science.gov (United States)

    Lakari, E; Pääkkö, P; Kinnula, V L

    1998-08-01

    The role of antioxidant defense mechanisms in the pathogenesis of granulomatous human lung diseases remains open to investigation. In this study we investigated the immunoreactivity of two important superoxide radical scavenging intracellular antioxidant enzymes, manganese superoxide dismutase (MnSOD) and copperzinc superoxide dismutase (CuZnSOD), in pulmonary sarcoidosis and extrinsic allergic alveolitis. In histologically normal lung MnSOD was variable but mostly positive in the cells of bronchial epithelium, alveolar epithelium especially in type II pneumocytes, and alveolar macrophages. Copperzinc SOD showed positive immunoreactivity most markedly in the bronchial epithelium. The biopsies of 22 patients with pulmonary sarcoidosis and 10 with extrinsic allergic alveolitis indicated that MnSOD was highly stained in the granulomas of both diseases, with 60 to 100% of the granulomas showing intensive immunoreactivity. Western blots conducted on the cell samples of bronchoalveolar lavage (BAL) fluid revealed significantly higher amounts of MnSOD in sarcoidosis and extrinsic allergic alveolitis than in the controls. Immunohistochemistry on the cells obtained from BAL fluid showed positive immunoreactivity of MnSOD in the macrophages but not in the lymphocytes. In contrast, copperzinc SOD was not induced in either of these diseases. We conclude that MnSOD is highly expressed in the granulomas of pulmonary sarcoidosis and extrinsic allergic alveolitis, and variable but mostly positive in alveolar macrophages, possibly owing to cytokine mediated induction during the granuloma formation.

  18. Unique Characteristics of Recombinant Hybrid Manganese Superoxide Dismutase from Staphylococcus equorum and S. saprophyticus.

    Science.gov (United States)

    Retnoningrum, Debbie S; Rahayu, Anis Puji; Mulyanti, Dina; Dita, Astrid; Valerius, Oliver; Ismaya, Wangsa T

    2016-04-01

    A recombinant hybrid of manganese dependent-superoxide dismutase of Staphylococcus equorum and S. saprophyticus has successfully been overexpressed in Escherichia coli BL21(DE3), purified, and characterized. The recombinant enzyme suffered from degradation and aggregation upon storage at -20 °C, but not at room temperature nor in cold. Chromatographic analysis in a size exclusion column suggested the occurrence of dimeric form, which has been reported to contribute in maintaining the stability of the enzyme. Effect of monovalent (Na(+), K(+)), divalent (Ca(2+), Mg(2+)), multivalent (Mn(2+/4+), Zn(2+/4+)) cations and anions (Cl(-), SO4 (2-)) to the enzyme stability or dimeric state depended on type of cation or anion, its concentration, and pH. However, tremendous effect was observed with 50 mM ZnSO4, in which thermostability of both the dimer and monomer was increased. Similar situation was not observed with MnSO4, and its presence was detrimental at 200 mM. Finally, chelating agent appeared to destabilize the dimer around neutral pH and dissociate it at basic pH. The monomer remained stable upon addition of ethylene diamine tetraacetic acid. Here we reported unique characteristics and stability of manganese dependent-superoxide dismutase from S. equorum/saprophyticus.

  19. Modeling Carbon Chain Anions in L1527

    CERN Document Server

    Harada, Nanase

    2008-01-01

    The low-mass protostellar region L1527 is unusual because it contains observable abundances of unsaturated carbon-chain molecules including CnH radicals, H2Cn carbenes, cyanopolyynes, and the negative ions C4H- and C6H-, all of which are more associated with cold cores than with protostellar regions. Sakai et al. suggested that these molecules are formed in L1527 from the chemical precursor methane, which evaporates from the grains during the heat-up of the region. With the gas-phase osu.03.2008 network extended to include negative ions of the families Cn-, and CnH-, as well as the newly detected C3N-, we modeled the chemistry that occurs following methane evaporation at T~ 25-30 K. We are able to reproduce most of the observed molecular abundances in L1527 at a time of ~5000 yr. At later times, the overall abundance of anions become greater than that of electrons, which has an impact on many organic species and ions. The anion-to-neutral ratio in our calculation is in good agreement with observation for C6H-...

  20. Role of extracellular superoxide dismutase in hypertension.

    Science.gov (United States)

    Gongora, Maria Carolina; Qin, Zhenyu; Laude, Karine; Kim, Ha Won; McCann, Louise; Folz, J Rodney; Dikalov, Sergey; Fukai, Tohru; Harrison, David G

    2006-09-01

    We previously found that angiotensin II-induced hypertension increases vascular extracellular superoxide dismutase (ecSOD), and proposed that this is a compensatory mechanism that blunts the hypertensive response and preserves endothelium-dependent vasodilatation. To test this hypothesis, we studied ecSOD-deficient mice. ecSOD(-/-) and C57Blk/6 mice had similar blood pressure at baseline; however, the hypertension caused by angiotensin II was greater in ecSOD(-/-) compared with wild-type mice (168 versus 147 mm Hg, respectively; P<0.01). In keeping with this, angiotensin II increased superoxide and reduced endothelium-dependent vasodilatation in small mesenteric arterioles to a greater extent in ecSOD(-/-) than in wild-type mice. In contrast to these findings in resistance vessels, angiotensin II paradoxically improved endothelium-dependent vasodilatation, reduced intracellular and extracellular superoxide, and increased NO production in aortas of ecSOD(-/-) mice. Whereas aortic expression of endothelial NO synthase, Cu/ZnSOD, and MnSOD were not altered in ecSOD(-/-) mice, the activity of Cu/ZnSOD was increased by 80% after angiotensin II infusion. This was associated with a concomitant increase in expression of the copper chaperone for Cu/ZnSOD in the aorta but not in the mesenteric arteries. Moreover, the angiotensin II-induced increase in aortic reduced nicotinamide-adenine dinucleotide phosphate oxidase activity was diminished in ecSOD(-/-) mice as compared with controls. Thus, during angiotensin II infusion, ecSOD reduces hypertension, minimizes vascular superoxide production, and preserves endothelial function in resistance arterioles. We also identified novel compensatory mechanisms involving upregulation of copper chaperone for Cu/ZnSOD, increased Cu/ZnSOD activity, and decreased reduced nicotinamide-adenine dinucleotide phosphate oxidase activity in larger vessels. These compensatory mechanisms preserve large vessel function when ecSOD is absent in

  1. Anionic surface binders

    Directory of Open Access Journals (Sweden)

    Aljaž-Rožič Mateja

    2004-01-01

    Full Text Available The MELAMIN Chemical Factory in Kočevje manufactures synthetic resins and binders for the paper industry. Binders based on AKD (alkyl ketene dimer are produced which are used for binding paper and cardboard in the range of neutral and partially basic pH. Cationic and, lately, anionic binders are mostly used for the bulk binding of paper and board. The possibility of using AKD binders on paper or board surfaces is presented. In this case partially cationic AKD binders may be applied. When optical whiteners are used, the application of AKD binders is recommended. In the case of paper it is possible to substitute acrylate binders by AKD binders. The best results are obtained when the paper is first partly treated in bulk and subsequently surface treated.

  2. Glutathione--hydroxyl radical interaction: a theoretical study on radical recognition process.

    Directory of Open Access Journals (Sweden)

    Béla Fiser

    Full Text Available Non-reactive, comparative (2 × 1.2 μs molecular dynamics simulations were carried out to characterize the interactions between glutathione (GSH, host molecule and hydroxyl radical (OH(•, guest molecule. From this analysis, two distinct steps were identified in the recognition process of hydroxyl radical by glutathione: catching and steering, based on the interactions between the host-guest molecules. Over 78% of all interactions are related to the catching mechanism via complex formation between anionic carboxyl groups and the OH radical, hence both terminal residues of GSH serve as recognition sites. The glycine residue has an additional role in the recognition of OH radical, namely the steering. The flexibility of the Gly residue enables the formation of further interactions of other parts of glutathione (e.g. thiol, α- and β-carbons with the lone electron pair of the hydroxyl radical. Moreover, quantum chemical calculations were carried out on selected GSH/OH(• complexes and on appropriate GSH conformers to describe the energy profile of the recognition process. The relative enthalpy and the free energy changes of the radical recognition of the strongest complexes varied from -42.4 to -27.8 kJ/mol and from -21.3 to 9.8 kJ/mol, respectively. These complexes, containing two or more intermolecular interactions, would be the starting configurations for the hydrogen atom migration to quench the hydroxyl radical via different reaction channels.

  3. Antiviral, immunomodulatory, and free radical scavenging activities of a protein-enriched fraction from the larvae of the housefly, Musca domestica.

    Science.gov (United States)

    Ai, Hui; Wang, Furong; Zhang, Na; Zhang, Lingyao; Lei, Chaoliang

    2013-01-01

    In our previous study, protein-enriched fraction (PEF) that was isolated from the larvae of the housefly, Musca domestica L. (Diptera: Muscidae), showed excellent hepatoprotective activity as well as the potential for clinical application in therapy for liver diseases. In this study, antiviral, immunomodulatory, and free radical scavenging activities of PEF were evaluated. The antiviral results demonstrated that PEF inhibited the infection of avian influenza virus H9N2 and had a virucidal effect against the multicapsid nucleopolyhedrovirus of the alfalfa looper, Autographa californica Speyer (Lepidoptera: Noctuidae) in vitro. The mortality of silkworm larve in a PEF treatment group decreased significantly compared with a negative control. PEF showed excellent scavenging activity for 1,1-diphenyl-2-picrylhydrazyl and superoxide anion radicals, which were similar to those of ascorbic acid. The imunomodulatory results suggested that PEF could effectively improve immune function in experimental mice. Our results indicated that PEF could possibly be used for the prophylaxis and treatment of diseases caused by avian influenza virus infection. In addition, PEF with virucidal activity against insect viruses might provide useful for the development of antimicrobial breeding technology for economically important insects. As a natural product from insects, PEF could be a potential source for the discovery of potent antioxidant and immunomodulatory agents.

  4. Complexes trans-[RuCl(2)(nic)(4)] and trans-[RuCl(2)(i-nic)(4)] as free radical scavengers.

    Science.gov (United States)

    Creczynski-Pasa, T B; Bonetti, V R; Beirith, A; Ckless, K; Konzen, M; Seifriz, I; Paula, M S; Franco, C V; Wilhelm Filho, D; Calixto, J B

    2001-09-01

    This study evaluates the action of the new ruthenium complexes trans-RuCl(2)(nic)(4)] (I) and trans-[RuCl(2)(i-nic)(4)] (II) as free radical scavengers. In our experiments, both compounds acted as scavengers of superoxide anion (O(2)*(-)), hydroxyl radicals (HO*) and nitrogen monoxide (formally known as 'nitric oxide'; NO*). In addition, complexes I and II potentiated the release of NO* from S-nitroso-N-acetyl-DL-penicilamine (SNAP), a NO* donor. Complex II, but not I, also decreased the nitrite levels in culture media of activated macrophages. A hypsochromic shift of lambda(max) and a significant change in half-wave potential (E(1/2)) was observed when NO* was added to the Complex II. Thiobarbituric reactive substance (TBARS) levels were significantly reduced in rats treated for 1 week with Complex II plus tert-butylhydroperoxide, when compared to rats treated only with tert-butylhydroperoxide. None of the complexes showed cytotoxicity. These findings support the suggestion that the new ruthenium complexes, especially trans-[RuCl(2)(i-nic)(4)] or its derivatives, might provide potential therapeutic benefits in disorders where reactive nitrogen (RNS) or oxygen (ROS) species are involved.

  5. Resonant spectra of quadrupolar anions

    Science.gov (United States)

    Fossez, K.; Mao, Xingze; Nazarewicz, W.; Michel, N.; Garrett, W. R.; Płoszajczak, M.

    2016-09-01

    In quadrupole-bound anions, an extra electron is attached at a sufficiently large quadrupole moment of a neutral molecule, which is lacking a permanent dipole moment. The nature of the bound states and low-lying resonances of such anions is of interest for understanding the threshold behavior of open quantum systems in general. In this work, we investigate the properties of quadrupolar anions as halo systems, the formation of rotational bands, and the transition from a subcritical to supercritical electric quadrupole moment. We solve the electron-plus-rotor problem using a nonadiabatic coupled-channel formalism by employing the Berggren ensemble, which explicitly contains bound states, narrow resonances, and the scattering continuum. The rotor is treated as a linear triad of point charges with zero monopole and dipole moments and nonzero quadrupole moment. We demonstrate that binding energies and radii of quadrupolar anions strictly follow the scaling laws for two-body halo systems. Contrary to the case of dipolar anions, ground-state band of quadrupolar anions smoothly extend into the continuum, and many rotational bands could be identified above the detachment threshold. We study the evolution of a bound state of an anion as it dives into the continuum at a critical quadrupole moment and we show that the associated critical exponent is α =2 . Everything considered, quadrupolar anions represent a perfect laboratory for the studies of marginally bound open quantum systems.

  6. Rutin inhibits proliferation, attenuates superoxide production and decreases adhesion and migration of human cancerous cells.

    Science.gov (United States)

    Ben Sghaier, Mohamed; Pagano, Alessandra; Mousslim, Mohamed; Ammari, Youssef; Kovacic, Hervé; Luis, José

    2016-12-01

    Lung and colorectal cancer are the principal causes of death in the world. Rutin, an active flavonoid compound, is known for possessing a wide range of biological activities. In this study, we examined the effect of rutin on the viability, superoxide anion production, adhesion and migration of human lung (A549) and colon (HT29 and Caco-2) cancer cell lines. In order to control the harmlessness of the tested concentrations of rutin, the viability of cancer cell lines was assessed using a 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. ROS generation was measured by lucigenin chemiluminescence detecting superoxide ions. To investigate the effect of rutin on the behavior of human lung and colon cancer cell lines, we performed adhesion assays, using various purified extracellular matrix (ECM) proteins. Finally, in vitro cell migration assays were explored using modified Boyden chambers. The viability of cancerous cells was inhibited by rutin. It also significantly attenuated the superoxide production in HT29 cells. In addition, rutin affected adhesion and migration of A549 and HT29 cell. These findings indicate that rutin, a natural molecule, might have potential as anticancer agent against lung and colorectal carcinogenesis.

  7. Sources of superoxide/H2O2 during mitochondrial proline oxidation

    Directory of Open Access Journals (Sweden)

    Renata L.S. Goncalves

    2014-01-01

    Full Text Available p53 Inducible gene 6 (PIG6 encodes mitochondrial proline dehydrogenase (PRODH and is up-regulated several fold upon p53 activation. Proline dehydrogenase is proposed to generate radicals that contribute to cancer cell apoptosis. However, there are at least 10 mitochondrial sites that can produce superoxide and/or H2O2, and it is unclear whether proline dehydrogenase generates these species directly, or instead drives production by other sites. Amongst six cancer cell lines, ZR75-30 human breast cancer cells had the highest basal proline dehydrogenase levels, and mitochondria isolated from ZR75-30 cells consumed oxygen and produced H2O2 with proline as sole substrate. Insects use proline oxidation to fuel flight, and mitochondria isolated from Drosophila melanogaster were even more active with proline as sole substrate than ZR75-30 mitochondria. Using mitochondria from these two models we identified the sites involved in formation of superoxide/H2O2 during proline oxidation. In mitochondria from Drosophila the main sites were respiratory complexes I and II. In mitochondria from ZR75-30 breast cancer cells the main sites were complex I and the oxoglutarate dehydrogenase complex. Even with combinations of substrates and respiratory chain inhibitors designed to minimize the contributions of other sites and maximize any superoxide/H2O2 production from proline dehydrogenase itself, there was no significant direct contribution of proline dehydrogenase to the observed H2O2 production. Thus proline oxidation by proline dehydrogenase drives superoxide/H2O2 production, but it does so mainly or exclusively by providing anaplerotic carbon for other mitochondrial dehydrogenases and not by producing superoxide/H2O2 directly.

  8. Sources of superoxide/H2O2 during mitochondrial proline oxidation.

    Science.gov (United States)

    Goncalves, Renata L S; Rothschild, Daniel E; Quinlan, Casey L; Scott, Gary K; Benz, Christopher C; Brand, Martin D

    2014-01-01

    p53 Inducible gene 6 (PIG6) encodes mitochondrial proline dehydrogenase (PRODH) and is up-regulated several fold upon p53 activation. Proline dehydrogenase is proposed to generate radicals that contribute to cancer cell apoptosis. However, there are at least 10 mitochondrial sites that can produce superoxide and/or H2O2, and it is unclear whether proline dehydrogenase generates these species directly, or instead drives production by other sites. Amongst six cancer cell lines, ZR75-30 human breast cancer cells had the highest basal proline dehydrogenase levels, and mitochondria isolated from ZR75-30 cells consumed oxygen and produced H2O2 with proline as sole substrate. Insects use proline oxidation to fuel flight, and mitochondria isolated from Drosophila melanogaster were even more active with proline as sole substrate than ZR75-30 mitochondria. Using mitochondria from these two models we identified the sites involved in formation of superoxide/H2O2 during proline oxidation. In mitochondria from Drosophila the main sites were respiratory complexes I and II. In mitochondria from ZR75-30 breast cancer cells the main sites were complex I and the oxoglutarate dehydrogenase complex. Even with combinations of substrates and respiratory chain inhibitors designed to minimize the contributions of other sites and maximize any superoxide/H2O2 production from proline dehydrogenase itself, there was no significant direct contribution of proline dehydrogenase to the observed H2O2 production. Thus proline oxidation by proline dehydrogenase drives superoxide/H2O2 production, but it does so mainly or exclusively by providing anaplerotic carbon for other mitochondrial dehydrogenases and not by producing superoxide/H2O2 directly.

  9. Lower Superoxide Dismutase 2 (SOD2) Protein Content in Mononuclear Cells Is Associated with Better Survival in Patients with Hemodialysis Therapy

    Science.gov (United States)

    Shen, Jianlin

    2016-01-01

    Mitochondrial superoxide dismutase 2 (SOD2) converts superoxide anions to hydrogen peroxide and oxygen. Human data on SOD2 protein content in chronic kidney disease (CKD) are sparse and mortality data are lacking. We investigated SOD2 protein content in monocytes from patients with hemodialysis therapy (n = 81), CKD stage 1–5 (n = 120), and healthy controls (n = 13) using in-cell Western assays. SOD2 protein decreased from CKD stage 1 until stage 4 whereas it increased again in stage 5 with and without hemodialysis. SOD2 gene expression, analyzed by quantitative real-time PCR, was not significantly different between the groups. Elevating cellular superoxide production reduced SOD2 protein content. This effect was abolished by the superoxide dismutase mimetic Tempol. Using gelelectrophoresis and Western blot we did not detect nitrotyrosine modifications of SOD2 in CKD. Finally, in patients with CKD stage 5 with hemodialysis therapy higher than median SOD2 protein content was associated with higher all-cause mortality. In conclusion, SOD2 protein content declined in CKD until stage 4 while SOD2 gene expression did not. Increased cellular superoxide anion production might affect SOD2 protein content. In advanced CKD (stage 5) SOD2 protein content increased again, but higher than median SOD2 protein content in these patients did not confer a survival benefit. PMID:27630759

  10. Lower Superoxide Dismutase 2 (SOD2 Protein Content in Mononuclear Cells Is Associated with Better Survival in Patients with Hemodialysis Therapy

    Directory of Open Access Journals (Sweden)

    Katharina Krueger

    2016-01-01

    Full Text Available Mitochondrial superoxide dismutase 2 (SOD2 converts superoxide anions to hydrogen peroxide and oxygen. Human data on SOD2 protein content in chronic kidney disease (CKD are sparse and mortality data are lacking. We investigated SOD2 protein content in monocytes from patients with hemodialysis therapy (n=81, CKD stage 1–5 (n=120, and healthy controls (n=13 using in-cell Western assays. SOD2 protein decreased from CKD stage 1 until stage 4 whereas it increased again in stage 5 with and without hemodialysis. SOD2 gene expression, analyzed by quantitative real-time PCR, was not significantly different between the groups. Elevating cellular superoxide production reduced SOD2 protein content. This effect was abolished by the superoxide dismutase mimetic Tempol. Using gelelectrophoresis and Western blot we did not detect nitrotyrosine modifications of SOD2 in CKD. Finally, in patients with CKD stage 5 with hemodialysis therapy higher than median SOD2 protein content was associated with higher all-cause mortality. In conclusion, SOD2 protein content declined in CKD until stage 4 while SOD2 gene expression did not. Increased cellular superoxide anion production might affect SOD2 protein content. In advanced CKD (stage 5 SOD2 protein content increased again, but higher than median SOD2 protein content in these patients did not confer a survival benefit.

  11. Lower Superoxide Dismutase 2 (SOD2) Protein Content in Mononuclear Cells Is Associated with Better Survival in Patients with Hemodialysis Therapy.

    Science.gov (United States)

    Krueger, Katharina; Shen, Jianlin; Maier, Alexandra; Tepel, Martin; Scholze, Alexandra

    2016-01-01

    Mitochondrial superoxide dismutase 2 (SOD2) converts superoxide anions to hydrogen peroxide and oxygen. Human data on SOD2 protein content in chronic kidney disease (CKD) are sparse and mortality data are lacking. We investigated SOD2 protein content in monocytes from patients with hemodialysis therapy (n = 81), CKD stage 1-5 (n = 120), and healthy controls (n = 13) using in-cell Western assays. SOD2 protein decreased from CKD stage 1 until stage 4 whereas it increased again in stage 5 with and without hemodialysis. SOD2 gene expression, analyzed by quantitative real-time PCR, was not significantly different between the groups. Elevating cellular superoxide production reduced SOD2 protein content. This effect was abolished by the superoxide dismutase mimetic Tempol. Using gelelectrophoresis and Western blot we did not detect nitrotyrosine modifications of SOD2 in CKD. Finally, in patients with CKD stage 5 with hemodialysis therapy higher than median SOD2 protein content was associated with higher all-cause mortality. In conclusion, SOD2 protein content declined in CKD until stage 4 while SOD2 gene expression did not. Increased cellular superoxide anion production might affect SOD2 protein content. In advanced CKD (stage 5) SOD2 protein content increased again, but higher than median SOD2 protein content in these patients did not confer a survival benefit.

  12. Levels of Lipid Perioxides and Superoxide Dismutase in Peritoneal Fluid of Patients with Endometriosis

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In order to evaluate the changes of lipid perioxides (LPO) and superoxide dismutase (SOD) levels in peritoneal fluid in patients with endometriosis, the levels of LPO and SOD in peritoneal fluids from infertile women with endometriosis and with normal pelvis were measured. The result showed that the levels of LPO but SOD was elevated significantly in peritoneal fluid from women with endometriosis than in women with normal pelvis (P<0.01). It is suggested that free oxygen radicals may be involved in the pathogenesis of endometriosis associated infertility.

  13. Study on stability and oxygen radicals scavenging capacity of acylated blueberries anthocyanins%酰基化蓝莓花色苷的稳定性和对氧自由基清除能力

    Institute of Scientific and Technical Information of China (English)

    李颖畅; 李冰心; 吕春茂; 孟宪军

    2012-01-01

    The instability of natural anthocyanins was a big obstacle for its usage in food as colorants.In order to improve the stability of anthocyanins, molecular modification was used.The molecular modification of blueberry anthocyanins by acylation, the light, thermal stability and scavenging oxygen radicals of acylated anthocyanins were studied.The UV absorption spectrum and infrared spectrum showed that the blueberry anthocyanins had been acylated.Light and heat stability of acylated anthocyanins were significantly increased being compared with no acylated anthocyanins, but the capability of acylated anthocyanins on scavenging the hydroxyl radical, superoxide anion radical were weaker than those no acylated anthocyanins.lC~0 of scavenging hydroxyl radical and superoxide anion was 0.74,3.14mg/mL, respectively.%由于天然花色苷稳定性差,严重阻碍了其在食品工业中的广泛应用。为了改善花色苷的稳定性,采用分子修饰的方法,通过酰基化反应修饰蓝莓花色苷,并研究酰化后蓝莓花色苷的光、热稳定性和对氧自由基的清除能力。通过紫外吸收光谱和红外光谱表明蓝莓花色苷已经酰基化。相对未酰化的蓝莓花色苷,酰基化蓝莓花色苷的光、热稳定性显著提高,但清除羟基自由基、超氧阴离子自由基的能力略有下降,清除羟自由基、超氧阴离子自由基的IC,。分别为0.74、3.14mg/mL。

  14. Synthesis of water-soluble cystine C60 derivative with catalyst and its active oxygen radical scavenging ability

    Institute of Scientific and Technical Information of China (English)

    Wen Chao Guan; Xiang Ying Tang; Li Zhen Huang; Hong Xu

    2007-01-01

    A novel water-soluble cystine C60 derivative was synthesized in the presence of the catalyst, tetrabutylammonium hydroxide (TBAH). The product was characterized by FT-IR, UV, 1H NMR, 13C NMR, MS and elemental analysis. Furthermore, the that cystine C60 derivative showed an excellent efficiency in eliminating superoxygen anion radical and hydroxyl radical. The 50%inhibition concentration (IC50) for superoxygen anion radical and hydroxyl radical were 0.167 and 0.008 mg/mL, respectively.

  15. Molecular mass spectrometric identification of superoxide dismutase in the liver of mice Mus musculus and Mus spretus using a metallomics analytical approach.

    Science.gov (United States)

    González-Fernández, M; García-Barrera, T; Gómez-Ariza, J L

    2011-11-01

    This paper reports the identification and quantification of superoxide dismutase in the liver of Mus musculus and Mus spretus mice using a metallomics analytical approach. The approach consisted of using orthogonal chromatographic systems coupled to ICP-MS and UV detectors. Size-exclusion fractionation of the cytosolic extracts was followed by anion-exchange chromatographic separation of Cu- and Zn-containing species. After purification then tryptic digestion, Cu- and Zn-containing superoxide dismutase was identified by nESI-QqTOF. The MS-MS spectra of doubly charged peptides, with the Mascot searching engine, were used to obtain the sequence of the protein.

  16. Influence of Aqueous Inorganic Anions on the Reactivity of Nanoparticles in TiO2 Photocatalysis.

    Science.gov (United States)

    Farner Budarz, Jeffrey; Turolla, Andrea; Piasecki, Aleksander F; Bottero, Jean-Yves; Antonelli, Manuela; Wiesner, Mark R

    2017-03-21

    The influence of inorganic anions on the photoreactivity and aggregation of titanium dioxide nanoparticles (NPs) was assessed by dosing carbonate, chloride, nitrate, phosphate, and sulfate as potassium salts at multiple concentrations. NP stability was monitored in terms of aggregate morphology and electrophoretic mobility (EPM). Aggregate size and fractal dimension were measured over time by laser diffraction, and the isoelectric point (IEP) as a function of anion and concentration was obtained by measuring EPM versus pH. Phosphate, carbonate, and to a lesser extent, sulfate decreased the IEP of TiO2 and stabilized NP suspensions owing to specific surface interactions, whereas this was not observed for nitrate and chloride. TiO2 NPs were exposed to UV-A radiation, and the photoreactivity was assessed by monitoring the production of reactive species over time both at the NP surface (photogenerated holes) and in the bulk solution (hydroxyl radicals) by observing their reactions with the selective probe compounds iodide and terephthalic acid, respectively. The generation of photogenerated holes and hydroxyl radicals was influenced by each inorganic anion to varying degrees. Carbonate and phosphate inhibited the oxidation of iodide, and this interaction was successfully described by a Langmuir-Hinshelwood mechanism and related to the characteristics of TiO2 aggregates. Chloride and nitrate do not specifically interact with TiO2, and sulfate creates relatively weak interactions with the TiO2 surface such that no decrease in photogenerated hole reactivity was observed. A decrease in hydroxyl radical generation was observed for all inorganic anions. Quenching rate constants for the reaction of hydroxyl radicals with each inorganic anion do not provide a comprehensive explanation for the magnitude of this decrease, which arises from the interplay of several physicochemical phenomena. This work shows that the reactivity of NPs will be strongly influenced by the makeup of

  17. A radical approach to radical innovation

    NARCIS (Netherlands)

    D. Deichmann (Dirk); J.C.M. van den Ende (Jan)

    2014-01-01

    textabstractInnovation 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?

  18. A radical approach to radical innovation

    OpenAIRE

    Deichmann, Dirk; van der Ende, Jan