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Sample records for high density free-radical

  1. Improvement of the thermal and thermo-oxidative stability of high-density polyethylene by free radical trapping of rare earth compound

    Energy Technology Data Exchange (ETDEWEB)

    Ran, Shiya; Zhao, Li; Han, Ligang [Laboratory of Polymer Materials and Engineering, Ningbo Institute of Technology, ZhejiangUniversity, Ningbo, 315100 (China); MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Institute of Polymer Composites, Zhejiang University, Hangzhou, 310027 (China); Guo, Zhenghong, E-mail: guozhenghong@nit.zju.edu.cn [Laboratory of Polymer Materials and Engineering, Ningbo Institute of Technology, ZhejiangUniversity, Ningbo, 315100 (China); Fang, Zhengping [Laboratory of Polymer Materials and Engineering, Ningbo Institute of Technology, ZhejiangUniversity, Ningbo, 315100 (China); MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Institute of Polymer Composites, Zhejiang University, Hangzhou, 310027 (China)

    2015-07-20

    Highlights: • Polyethylene filled with ytterbium trifluoromethanesulfonate was prepared. • A low Yb loading improved thermal stability of PE obviously by radical trapping. • Yb(OTf){sub 3} is expected to be an efficient thermal stabilizer for the polymer. - Abstract: A kind of rare earth compound, ytterbium trifluoromethanesulfonate (Yb(OTf){sub 3}), was introduced into high-density polyethylene (HDPE) by melt compounding to investigate the effect of Yb(OTf){sub 3} on the thermal and thermo-oxidative stability of HDPE. The results of thermogravimetric (TG) and differential scanning calorimetry (DSC) showed that the addition of Yb(OTf){sub 3} made the thermal degradation temperatures dramatically increased, the oxidative induction time (OIT) extended, and the enthalpy (ΔH{sub d}) reduced. Very low Yb(OTf){sub 3} loading (0.5 wt%) in HDPE could increase the onset degradation temperature in air from 334 to 407 °C, delay the OIT from 11.0 to 24.3 min, and decrease the ΔH{sub d} from 61.0 to 13.0 J/g remarkably. Electron spin resonance spectra (ESR), thermogravimetric analysis coupled to Fourier transform infrared spectroscopy (TGA-FTIR), rheological investigation and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) indicated that the free radicals-trapping ability of Yb(OTf){sub 3} was responsible for the improved thermal and thermo-oxidative stability.

  2. Free radicals. High-resolution spectroscopy and molecular structure

    International Nuclear Information System (INIS)

    Hirota, E.

    1983-01-01

    High-resolution, high-sensitivity spectroscopy using CW laser and microwave sources has been applied to free radicals and transient molecules to establish their existence and to explore their properties in detail. The radicals studied were mainly generated by discharge-induced reactions. A few molecules are used as typical examples to illustrate the results so far obtained. The molecular and electronic structures of free radicals, intramolecular motions of large amplitudes in some labile molecules, and metastable electronic states of carbenes are given special emphasis. The significance of the present spectroscopic results in other related fields such as astronomy and atmospheric chemistry is stressed. 4 figures, 3 tables

  3. Modification of Ultra-High Vacuum Surfaces Using Free Radicals

    CERN Document Server

    Vorlaufer, G

    2002-01-01

    In ultra-high vacuum systems outgassing from vacuum chamber walls and desorption of surface adsorbates are usually the factors which determine pressure and residual gas composition. In particular in beam vacuum systems of accelerators like the LHC, where surfaces are exposed to intense synchrotron radiation and bombardment by energetic ions and electrons, surface properties like the molecular desorption yield or secondary electron yield can strongly influence the performance of the accelerator. Well-established treatment methods like vacuum bake-out or glow-discharge cleaning have been successfully applied in the past to condition ultra-high vacuum surfaces, but these methods are sometimes difficult to carry out, for example if the vacuum chambers are not accessible. In this work, an alternative treatment method is investigated. This method is based on the strong chemical reactivity of free radicals, electrically neutral fragments of molecules. Free radicals (in the case of this work, nitrogen and oxygen radi...

  4. Simplifying the free-radical polymerization of styrene : microwave-assisted high-temperature auto polymerizations

    NARCIS (Netherlands)

    Erdmenger, T.; Becer, C.R.; Hoogenboom, R.; Schubert, U.S.

    2009-01-01

    We have investigated the combination of the thermally auto-initiated free radical polymn. of styrene and pptn. polymn. in order to develop a fast and environmentally friendly approach to produce polystyrene. To achieve high reaction temps. in a short period of time, microwave irradn. was utilized as

  5. Free radical production by high energy shock waves--comparison with ionizing irradiation.

    Science.gov (United States)

    Morgan, T R; Laudone, V P; Heston, W D; Zeitz, L; Fair, W R

    1988-01-01

    Fricke chemical dosimetry is used as an indirect measure of the free radical production of ionizing irradiation. We adapted the Fricke ferrous sulfate radiation dosimeter to examine the chemical effects of high energy shock waves. Significant free radical production was documented. The reaction was dose dependent, predictably increased by acoustic impedance, but curvilinear. A thousand shocks at 18 kilovolts induced the same free radical oxidation as 1100 rad cobalt-60 gamma ionizing irradiation, increasing to 2900 rad in the presence of an air-fluid zone of acoustic impedance. The biological effect of these free radicals was compared to that of cobalt-60 ionizing irradiation by measuring the affect on Chinese hamster cells by clonogenic assay. While cobalt-60 irradiation produced a marked decrease in clonogenic survivors, little effect was noted with high energy shock waves. This suggested that the chemical effects produced by shock waves were either absent or attenuated in the cells, or were inherently less toxic than those of ionizing irradiation.

  6. Graphdiyne Nanoparticles with High Free Radical Scavenging Activity for Radiation Protection.

    Science.gov (United States)

    Xie, Jiani; Wang, Ning; Dong, Xinghua; Wang, Chengyan; Du, Zhen; Mei, Linqiang; Yong, Yuan; Huang, Changshui; Li, Yuliang; Gu, Zhanjun; Zhao, Yuliang

    2018-03-06

    Numerous carbon networks materials comprised of benzene moieties, such as graphene and fullerene, have held great fascination for radioprotection because of their acknowledged good biocompatibility and strong free radical scavenging activity derived from their delocalized π-conjugated structure. Recently, graphdiyne, a new emerging carbon network material consisting of a unique chemical structure of benzene and acetylenic moieties, has gradually attracted attention in many research fields. Encouraged by its unique structure with strong conjugated π-system and highly reactive diacetylenic linkages, graphdiyne might have free radical activity and can thus be used as a radioprotector, which has not been investigated so far. Herein, for the first time, we synthesized bovine serum albumin (BSA)-modified graphdiyne nanoparticles (graphdiyne-BSA NPs) to evaluate their free radical scavenging ability and investigate their application for radioprotection both in cell and animal models. In vitro studies indicated that the graphdiyne-BSA NPs could effectively eliminate the free-radicals, decrease radiation-induced DNA damage in cells, and improve the viability of cells under ionizing radiation. In vivo experiments showed that the graphdiyne-BSA NPs could protect the bone marrow DNA of mice from radiation-induced damage and make the superoxide dismutase (SOD) and malondialdehyde (MDA) (two kinds of vital indicators of radiation-induced injury) recover back to normal levels. Furthermore, the good biocompatibility and negligible systemically toxicity responses of the graphdiyne-BSA NPs to mice were verified. All these results manifest the good biosafety and radioprotection activity of graphdiyne-BSA NPs to normal tissues. Therefore, our studies not only provide a new radiation protection platform based on graphdiyne for protecting normal tissues from radiation-caused injury but also provide a promising direction for the application of graphdiyne in the biomedicine field.

  7. Extraction method for high free radical scavenging activity of Siamese neem tree flowers

    Directory of Open Access Journals (Sweden)

    Worarat Chaisawangwong

    2009-10-01

    Full Text Available Siamese neem tree (Azadirachta indica A. Juss. var. siamensis Valeton is a medicinal plant found in Thailand. Youngleaves and young flowers of this plant are commonly consumed as a bitter tonic vegetable. The flowers are also used fortreatment of fever. The flower extract has been reported to exhibit in vitro free radical scavenging activity and can inhibitlipid peroxidation of bronchogenic cancer cell line. Active compounds in the flowers are flavonoids such as rutin andquercetin. The content of these compounds in the crude extract depends on the method of extraction. Therefore, the appropriateextraction method promoting high yield of total flavonoids and high free radical scavenging activity was investigated inthis study. Six different extraction methods, i.e. maceration, percolation, decoction, soxhlet extraction, ultrasonic extraction(UE, and microwave assisted extraction (MA were carried out for extracting dried powder of Siamese neem tree young flowers. The solvent used for maceration, percolation, and soxhlet extraction was 50% ethanol, while distilled water was used for decoction and MA, and both solvents were used for UE. The content of crude extract, free radical scavenging activity, and total flavonoids content of each extract were investigated and compared. Comparing the various extraction methods, decoction provided an extract containing a high amount of total flavonoids (17.54 mgRE/g extract and promoting the highest scavenging activity at EC50 11.36 g/ml. Decoction is also simple, cheap, and convenient and could be used in developing countries. Thus, it should be the recommended extraction method for the flowers of Siamese neem tree for furtherdevelopment of antioxidant pharmaceutical preparations.

  8. High-frequency electromagnetic radiation and the production of free radicals in four mouse organs

    Czech Academy of Sciences Publication Activity Database

    Barcal, J.; Stopka, Pavel; Křížová, Jana; Vrba, J.; Vožeh, F.

    2014-01-01

    Roč. 56, 1-2 (2014), s. 9-14 ISSN 1337-933X Institutional support: RVO:61388980 Keywords : Free radicals * Mobile phones * Paramagnetic resonance spectroscopy * Radiation Subject RIV: CA - Inorganic Chemistry

  9. Fetal programming and early identification of newborns at high risk of free radical-mediated diseases.

    Science.gov (United States)

    Perrone, Serafina; Santacroce, Antonino; Picardi, Anna; Buonocore, Giuseppe

    2016-05-08

    Nowadays metabolic syndrome represents a real outbreak affecting society. Paradoxically, pediatricians must feel involved in fighting this condition because of the latest evidences of developmental origins of adult diseases. Fetal programming occurs when the normal fetal development is disrupted by an abnormal insult applied to a critical point in intrauterine life. Placenta assumes a pivotal role in programming the fetal experience in utero due to the adaptive changes in structure and function. Pregnancy complications such as diabetes, intrauterine growth restriction, pre-eclampsia, and hypoxia are associated with placental dysfunction and programming. Many experimental studies have been conducted to explain the phenotypic consequences of fetal-placental perturbations that predispose to the genesis of metabolic syndrome, obesity, diabetes, hyperinsulinemia, hypertension, and cardiovascular disease in adulthood. In recent years, elucidating the mechanisms involved in such kind of process has become the challenge of scientific research. Oxidative stress may be the general underlying mechanism that links altered placental function to fetal programming. Maternal diabetes, prenatal hypoxic/ischaemic events, inflammatory/infective insults are specific triggers for an acute increase in free radicals generation. Early identification of fetuses and newborns at high risk of oxidative damage may be crucial to decrease infant and adult morbidity.

  10. Modeling of free radical polymerization up to high conversion. II. Development of a mathematical model.

    NARCIS (Netherlands)

    Tefera shibeshe, N.; Tefera, N.; Weickert, G.; Westerterp, K.R.

    1997-01-01

    In free radical polymerization diffusion-controlled processes take place simultaneously to the normal chemical reactions. Despite extensive efforts to model such processes a consistent model for the design of a polymerization reactor has not yet been established. In this article a semiempirical

  11. Characterization of Free Radicals By Electron Spin Resonance Spectroscopy in Biochars from Pyrolysis at High Heating Rates and at High Temperatures

    DEFF Research Database (Denmark)

    Trubetskaya, Anna; Jensen, Anker Degn; Larsen Andresen, Mogens

    of mathematical models that can predict yields, composition and rates of product (char, tar, light gases) formation from fast pyrolysis. The modeling of cross-linking and polymerization reactions in biomass pyrolysis includes the formation of free radicals and their disappearance. Knowledge about these radical...... reactions is important in order to achieve the high fuel conversion at short residence times. However, little is known about the extent of free radical reactions in pulverized biomass at fast pyrolysis conditions.The concentration and type of free radicals from the decay (termination stage) of pyrolysis...... to the less efficient catalytic effects of potassium on the bond-breaking and radical re-attachments. The high Si levels in the rice husk caused an increase in the char radical concentration compared to the wheat straw because the free radicals were trapped in a char consisting of a molten amorphous silica...

  12. Physiology of free radicals

    Directory of Open Access Journals (Sweden)

    Stevanović Jelka

    2011-01-01

    Full Text Available Free radicals imply that every atom, molecule, ion, group of atoms, or molecules with one or several non-paired electrons in outer orbital. Among these are: nitrogenoxide (NO•, superoxide-anion-radical (O2•-, hydroxyl radical (OH•, peroxyl radical (ROO•, alcoxyl radical (RO• and hydroperoxyl radical (HO2•. However, reactive oxygen species also include components without non-paired electrons in outer orbital (so-called reactive non-radical agents, such as: singlet oxygen (1O2, peroxynitrite (ONOO-, hydrogen-peroxide (H2O2, hypochloric acid (eg. HOCl and ozone (O3. High concentrations of free radicals lead to the development of oxidative stress which is a precondition for numerous pathological effects. However, low and moderate concentrations of these matter, which occur quite normally during cell metabolic activity, play multiple significant roles in many reactions. Some of these are: regulation of signal pathways within the cell and between cells, the role of chemoattractors and leukocyte activators, the role in phagocytosis, participation in maintaining, changes in the position and shape of the cell, assisting the cell during adaption and recovery from damage (e.g.caused by physical effort, the role in normal cell growth, programmed cell death (apoptosis and cell ageing, in the synthesis of essential biological compounds and energy production, as well as the contribution to the regulation of the vascular tone, actually, tissue vascularization.

  13. Free radical inactivation of trypsin

    International Nuclear Information System (INIS)

    Cudina, Ivana; Jovanovic, S.V.

    1988-01-01

    Reactivities of free radical oxidants, radical OH, Br2-anion radical and Cl 3 COO radical and a reductant, CO2-anion radical, with trypsin and reactive protein components were determined by pulse radiolysis of aqueous solutions at pH 7, 20 0 C. Highly reactive free radicals, radical OH, Br2-anion radical and CO2-anion radical, react with trypsin at diffusion controlled rates. Moderately reactive trichloroperoxy radical, k(Cl 3 COO radical + trypsin) preferentially oxidizes histidine residues. The efficiency of inactivation of trypsin by free radicals is inversely proportional to their reactivity. The yields of inactivation of trypsin by radical OH, Br2-anion radical and CO2-anion radical are low, G(inactivation) = 0.6-0.8, which corresponds to ∼ 10% of the initially produced radicals. In contrast, Cl 3 COO radical inactivates trypsin with ∼ 50% efficiency, i.e. G(inactivation) = 3.2. (author)

  14. High-field/ high-frequency EPR study on stable free radicals formed in sucrose by gamma-irradiation.

    Science.gov (United States)

    Georgieva, Elka R; Pardi, Luca; Jeschke, Gunnar; Gatteschi, Dante; Sorace, Lorenzo; Yordanov, Nicola D

    2006-06-01

    The EPR spectrum of sucrose irradiated by high-energy radiation is complex due to the presence of more than one radical species. In order to decompose the spectrum and elucidate the radical magnetic parameters a high-field (HF(-)EPR) study on stable free radicals in gamma-irradiated polycrystalline sucrose (table sugar) was performed at three different high frequencies--94, 190 and 285 GHz as well as at the conventional X-band. We suggest a presence of three stable radicals R1, R2 and R3 as the main radical species. Due to the increase of g-factor resolution at high fields the g-tensors of these radicals could be extracted by accurate simulations. The moderate g-anisotropy suggests that all three radicals are carbon-centred. Results from an earlier ENDOR study on X-irradiated sucrose single crystals (Vanhaelewyn et al., Appl Radiat Isot, 52, 1221 (2000)) were used for analyzing of the spectra in more details. It was confirmed that the strongest hyperfine interaction has a relatively small anisotropy, which indicates either the absence of alpha-protons or a strongly distorted geometry of the radicals.

  15. Comparison between Two Bromine Containing Free Radical Initiators in PRESAGE®

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyeonsuk; Ryu, Dongmin; Ye, Sung-Joon [Seoul National University, Seoul (Korea, Republic of)

    2016-10-15

    PRESAGE® is an optically clear 3-D polyurethane dosimeter which contains a halogenated carbon as a free radical initiator and leucomalachite dye. The change of the optical density is known to be linear with respect to the absorbed dose and the sensitivity is related to the carbon–halogen bond dissociation energy of the free radical initiator. Although there are some studies regarding free radical initiators and dye materials, there’s a lack of reports about the effect of other elements like LMG solvent which can be added when there’s a difficulty mixing materials. Also, there are some studies about comparison between free radicals with different kind of halogen atoms but there’s a lack of studies of comparison between initiators with the same halogen atom. In this experiments, two kinds of halocarbon free radical initiator with the same halogen atom (bromine) as well as the effect of the LMG solvent were studied to use the dosimeter as a therapeutic purpose. Effective atomic numbers were also calculated. The initiators with the same halogen atom, CBr{sub 4} and C{sub 2}H{sub 2}Br{sub 4}, reacted totally differently. CBr{sub 4} was more sensitive to the radiation and emitted maximum 4 times more free radicals upon irradiation with no additional effective atomic number but the absorbance after irradiation was highly variable with time. For stable measurement, C{sub 2}H{sub 2}Br{sub 4} would be more appropriate as a free radical initiator.

  16. Characterization of free radicals by electron spin resonance spectroscopy in biochars from pyrolysis at high heating rates and at high temperatures

    DEFF Research Database (Denmark)

    Trubetskaya, Anna; Jensen, Peter Arendt; Jensen, Anker Degn

    2016-01-01

    The concentration and type of free radicals from the decay (termination stage) of pyrolysis at slow and fast heating rates and at high temperatures (above 1000°C) in biomass char have been studied. A room temperature electron spin resonance spectroscopy study was conducted on original wood...... because the free radicals were trapped in a char consisting of a molten amorphous silica at heating rates of 103-104 K s-1. The experimental electron spin resonance spectroscopy spectra were analyzed by fitting to simulated data in order to identify radical types, based on g-values and line widths......, herbaceous biomass, holocelluloses, lignin and their chars, prepared at high temperatures in a wire mesh reactor, an entrained flow reactor, and a tubular reactor. The radical concentrations in the chars from the decay stage range up between 7·1016 and 1.5·1018 spins g -1. The results indicated...

  17. Free radical explosive composition

    Science.gov (United States)

    Walker, Franklin E.; Wasley, Richard J.

    1979-01-01

    An improved explosive composition is disclosed and comprises a major portion of an explosive having a detonation velocity between about 1500 and 10,000 meters per second and a minor amount of a getter additive comprising a compound or mixture of compounds capable of capturing or deactivating free radicals or ions under mechanical or electrical shock conditions and which is not an explosive. Exemplary getter additives are isocyanates, olefins and iodine.

  18. High hydrostatic pressure leads to free radicals accumulation in yeast cells triggering oxidative stress.

    Science.gov (United States)

    Bravim, Fernanda; Mota, Mainã M; Fernandes, A Alberto R; Fernandes, Patricia M B

    2016-08-01

    Saccharomyces cerevisiae is a unicellular organism that during the fermentative process is exposed to a variable environment; hence, resistance to multiple stress conditions is a desirable trait. The stress caused by high hydrostatic pressure (HHP) in S. cerevisiae resembles the injuries generated by other industrial stresses. In this study, it was confirmed that gene expression pattern in response to HHP displays an oxidative stress response profile which is expanded upon hydrostatic pressure release. Actually, reactive oxygen species (ROS) concentration level increased in yeast cells exposed to HHP treatment and an incubation period at room pressure led to a decrease in intracellular ROS concentration. On the other hand, ethylic, thermic and osmotic stresses did not result in any ROS accumulation in yeast cells. Microarray analysis revealed an upregulation of genes related to methionine metabolism, appearing to be a specific cellular response to HHP, and not related to other stresses, such as heat and osmotic stresses. Next, we investigated whether enhanced oxidative stress tolerance leads to enhanced tolerance to HHP stress. Overexpression of STF2 is known to enhance tolerance to oxidative stress and we show that it also leads to enhanced tolerance to HHP stress. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  19. Muon substituted free radicals

    International Nuclear Information System (INIS)

    Burkhard, P.; Fischer, H.; Roduner, E.; Strub, W.; Gygax, F.N.; Brinkman, G.A.; Louwrier, P.W.F.; McKenna, D.; Ramos, M.; Webster, B.C.

    1984-01-01

    Spin polarized energetic positive muons are injected as magnetic probes into unsaturated organic liquids. They are implemented via fast chemical processes ( -10 s) in various molecules. Of particular interest among these are muonium substituted free radicals. The technique allows determination of accurate rate coefficients for fast chemical reactions of radicals. Furthermore, radiochemical processes occuring in picoseconds after injection of the muon are studied. Of fundamental interest are also the structural and dynamical implications of substituting a proton by a muon, or in other terms, a hydrogen atom by a muonium atom. Selected examples for each of these three types of experiments are given. (Auth.)

  20. Total free radical species and oxidation equivalent in polluted air.

    Science.gov (United States)

    Wang, Guoying; Jia, Shiming; Niu, Xiuli; Tian, Haoqi; Liu, Yanrong; Chen, Xuefu; Li, Lan; Zhang, Yuanhang; Shi, Gaofeng

    2017-12-31

    Free radicals are the most important chemical intermediate or agent of the atmosphere and influenced by thousands of reactants. The free radicals determine the oxidizing power of the polluted air. Various gases present in smog or haze are oxidants and induce organ and cellular damage via generation of free radical species. At present, however, the high variability of total free radicals in polluted air has prevented the detection of possible trends or distributions in the concentration of those species. The total free radicals are a kind of contaminants with colorless, tasteless characteristics, and almost imperceptible by human body. Here we present total free radical detection and distribution characteristics, and analyze the effects of total free radicals in polluted air on human health. We find that the total free radical values can be described by not only a linear dependence on ozone at higher temperature period, but also a linear delay dependence on particulate matter at lower temperature period throughout the measurement period. The total free radical species distribution is decrease from west to east in Lanzhou, which closely related to the distribution of the air pollutants. The total free radical oxidation capacity in polluted air roughly matches the effects of tobacco smoke produced by the incomplete combustion of a controlled amount of tobacco in a smoke chamber. A relatively unsophisticated chromatographic fingerprint similarity is used for indicating preliminarily the effect of total free radicals in polluted air on human health. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. High-performance liquid chromatography coupled with post-column dual-bioactivity assay for simultaneous screening of xanthine oxidase inhibitors and free radical scavengers from complex mixture.

    Science.gov (United States)

    Li, D Q; Zhao, J; Li, S P

    2014-06-06

    Xanthine oxidase (XO) can catalyze hypoxanthine and xanthine to generate uric acid and reactive oxygen species (ROS), including superoxide anion radical (O₂(•-)) and hydrogen peroxide. XO inhibitors and free radical scavengers are beneficial to the treatment of gout and many related diseases. In the present study, an on-line high-performance liquid chromatography (HPLC) coupled with post-column dual-bioactivity assay was established and successfully applied to simultaneously screening of XO inhibitors and free radical scavengers from a complex mixture, Oroxylum indicum extract. The integrated system of HPLC separation, bioactivity screening and mass spectrometry identification was proved to be simple and effective for rapid and sensitive screening of individual bioactive compounds in complex mixtures. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Lipid nanocarriers based on natural oils with high activity against oxygen free radicals and tumor cell proliferation

    International Nuclear Information System (INIS)

    Lacatusu, I.; Badea, N.; Badea, G.; Oprea, O.; Mihaila, M.A.; Kaya, D.A.; Stan, R.; Meghea, A.

    2015-01-01

    The development of nano-dosage forms of phytochemicals represents a significant progress of the scientific approach in the biomedical research. The aim of this study was to assess the effectiveness of lipid nanocarriers based on natural oils (grape seed oil, fish oil and laurel leaf oil) in counteracting free radicals and combating certain tumor cells. No drug was encapsulated in the nanocarriers. The cytotoxic effect exerted by bioactive nanocarriers against two tumor cells, MDA-MB 231 and HeLa cell lines, and two normal cells, L929 and B16 cell lines, was measured using the MTT assay, while oxidative damage was assessed by measuring the total antioxidant activity using chemiluminescence analysis. The best performance was obtained for nanocarriers based on an association of grape seed and laurel leaf oils, with a capacity to scavenge about 98% oxygen free radicals. A dose of nanocarriers of 5 mg·mL −1 has led to a drastic decrease in tumor cell proliferation even in the absence of an antitumor drug (e.g. about 50% viability for MDA-MB 231 cell line and 60% viability for HeLa cell line). A comparative survival profile of normal and tumor cells, which were exposed to an effective dose of 2.5 mg·mL −1 lipid nanocarriers, has revealed a death rate of 20% for normal B16 cells and of 40% death rate for MDA-MB 231 and HeLa tumor cells. The results in this study imply that lipid nanocarriers based on grape seed oil in association with laurel leaf oil could be a candidate to reduce the delivery system toxicity and may significantly improve the therapeutic efficacy of antitumor drugs in clinical applications. - Highlights: • Functional lipid nanocarriers with unique features and broad spectrum effectiveness • Lipid nanocarriers based on laureal leaf oil (LLO) and grape seed oil (GSO) • Antioxidant activity has reached 98% for nanocarriers containing 25% GSO and 2% LLO. • LLO exerts a significant cytotoxic effect against HeLa and MDA-MB 231 tumor cells. • 50

  3. Lipid nanocarriers based on natural oils with high activity against oxygen free radicals and tumor cell proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Lacatusu, I.; Badea, N.; Badea, G.; Oprea, O. [University Politehnica of Bucharest, Faculty of Applied Chemistry and Materials Science, Polizu Street No 1, 011061 Bucharest (Romania); Mihaila, M.A. [Institute of Virusology “Stefan S. Nicolau”, Center of Immunology, Bravu Road, No. 285, 030304 Bucharest (Romania); Kaya, D.A. [Department of Field Crops, Faculty of Agriculture, Mustafa Kemal University, 31030 Antakya, Hatay (Turkey); Stan, R., E-mail: rl_stan2000@yahoo.com [University Politehnica of Bucharest, Faculty of Applied Chemistry and Materials Science, Polizu Street No 1, 011061 Bucharest (Romania); Meghea, A. [University Politehnica of Bucharest, Faculty of Applied Chemistry and Materials Science, Polizu Street No 1, 011061 Bucharest (Romania)

    2015-11-01

    The development of nano-dosage forms of phytochemicals represents a significant progress of the scientific approach in the biomedical research. The aim of this study was to assess the effectiveness of lipid nanocarriers based on natural oils (grape seed oil, fish oil and laurel leaf oil) in counteracting free radicals and combating certain tumor cells. No drug was encapsulated in the nanocarriers. The cytotoxic effect exerted by bioactive nanocarriers against two tumor cells, MDA-MB 231 and HeLa cell lines, and two normal cells, L929 and B16 cell lines, was measured using the MTT assay, while oxidative damage was assessed by measuring the total antioxidant activity using chemiluminescence analysis. The best performance was obtained for nanocarriers based on an association of grape seed and laurel leaf oils, with a capacity to scavenge about 98% oxygen free radicals. A dose of nanocarriers of 5 mg·mL{sup −1} has led to a drastic decrease in tumor cell proliferation even in the absence of an antitumor drug (e.g. about 50% viability for MDA-MB 231 cell line and 60% viability for HeLa cell line). A comparative survival profile of normal and tumor cells, which were exposed to an effective dose of 2.5 mg·mL{sup −1} lipid nanocarriers, has revealed a death rate of 20% for normal B16 cells and of 40% death rate for MDA-MB 231 and HeLa tumor cells. The results in this study imply that lipid nanocarriers based on grape seed oil in association with laurel leaf oil could be a candidate to reduce the delivery system toxicity and may significantly improve the therapeutic efficacy of antitumor drugs in clinical applications. - Highlights: • Functional lipid nanocarriers with unique features and broad spectrum effectiveness • Lipid nanocarriers based on laureal leaf oil (LLO) and grape seed oil (GSO) • Antioxidant activity has reached 98% for nanocarriers containing 25% GSO and 2% LLO. • LLO exerts a significant cytotoxic effect against HeLa and MDA-MB 231 tumor

  4. Donor free radical explosive composition

    Science.gov (United States)

    Walker, Franklin E. [15 Way Points Rd., Danville, CA 94526; Wasley, Richard J. [4290 Colgate Way, Livermore, CA 94550

    1980-04-01

    An improved explosive composition is disclosed and comprises a major portion of an explosive having a detonation velocity between about 1500 and 10,000 meters per second and a minor amount of a donor additive comprising an organic compound or mixture of organic compounds capable of releasing low molecular weight free radicals or ions under mechanical or electrical shock conditions and which is not an explosive, or an inorganic compound or mixture of inorganic compounds capable of releasing low molecular weight free radicals or ions under mechanical or electrical shock conditions and selected from ammonium or alkali metal persulfates.

  5. Measurements of Free Radical in Vitamin E-Doped Ultra-High Molecular Weight Polyethylene: Dependence on Materials Processing and Irradiation Environments

    International Nuclear Information System (INIS)

    Ridley, M. D.

    2006-01-01

    In an effort to combat oxidation of the load-bearing, polyethylene (PE) components of total hip- and knee-joint replacement devices, antioxidant such as vitamin E (α-Tocopherol (α-T)) has been introduced into polymer matrix. In this study we investigated effect of α-T on free radicals in medical grade ultra-high molecular weight polyethylene (UHMWPE), GUR 1020 resin. Since oxidation resistance depends on radical reaction, we used electron spin resonance (ESR) technique for direct detection of free radicals before and after irradiation. High concentration (20% by vol.) of α-T was used so its ESR signal (due to α-T-O degree radical) could be distinguished among the overwhelming signals due to PE radicals. Two groups of samples were investigated. In one group, samples were prepared from blends of α-T and UHMWPE powder (α-T-P), and in the second group, from compression molded blocks (α-T-B). In each group, samples were γ-irradiated in sealed packages filled with N 2 , or in open air, and free radicals were measured in open air environment as a function of time. Also included in this study were α-T, and powder resin and compression molded blocks without any α-T. Following irradiation in air, α-T-P and α-T produced identical ESR spectra showing characteristic feature of α-T-O degree radical. Absence of PE radicals in the ESR signals suggests quenching/repairing of PE radicals by α-T in presence of oxygen. However, when irradiation was performed in N 2 , ESR signals of α-T-P exhibited superimposed resonance lines due to PE and α-T-O degree radicals. Furthermore, presence of a-T or α-T-O degree radicals did not prevent subsequent oxidation of PE radicals in producing stable, oxygen-induced radicals (OIR). Post-irradiation oxidation index measured by FTIR, however, did not show any difference between these samples. Compression molded samples, with or without α-T, produced ESR spectra showing features characteristics of PE radicals only, and there was no

  6. Development and validation of a simple high performance thin layer chromatography method combined with direct 1,1-diphenyl-2-picrylhydrazyl assay to quantify free radical scavenging activity in wine.

    Science.gov (United States)

    Agatonovic-Kustrin, Snezana; Morton, David W; Yusof, Ahmad P

    2016-04-15

    The aim of this study was to: (a) develop a simple, high performance thin layer chromatographic (HPTLC) method combined with direct 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay to rapidly assess and compare free radical scavenging activity or anti-oxidant activity for major classes of polyphenolics present in wines; and (b) to investigate relationship between free radical scavenging activity to the total polyphenolic content (TPC) and total antioxidant capacity (TAC) in the wine samples. The most potent free radical scavengers that we tested for in the wine samples were found to be resveratrol (polyphenolic non-flavonoid) and rutin (flavonoid), while polyphenolic acids (caffeic acid and gallic acid) although present in all wine samples were found to be less potent free radical scavengers. Therefore, the total antioxidant capacity was mostly affected by the presence of resveratrol and rutin, while total polyphenolic content was mostly influenced by the presence of the less potent free radical scavengers gallic and caffeic acids. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Free radical transfer in polymers

    International Nuclear Information System (INIS)

    Sonntag, C. von; Bothe, E.; Ulanski, P.

    1998-01-01

    For the present study of free-radical transfer in polymers pulse radiolysis and product studies have been carried out in aqueous solutions using thus far only the water-soluble polymers polyacrylic acid, polymethacrylic acid and polyvinyl alcohol. When OH radicals, generated in the radiolysis of N 2 O-saturated aqueous solutions, react with polymers the lifetime of the polymer radical thus created very much depends on the number of radicals per polymer chain. When there are a large number of radicals per chain their bimolecular decay may be faster than the corresponding (diffusion controlled) decay of monomeric radicals, but when the macromolecule contains only few or even just one radical their lifetime is considerably prolonged. Highly charged polymers such as polyacrylic acid at high pH attain a rod-like conformation which again favors a long lifetime of the radicals. Under such conditions, radical transfer reactions can occur. For example, in polyacrylic acid OH radicals generate two kinds of radicals side by side. The radical in β-position to the carboxylate group converts into the thermodynamically more stable α-radicals by an H-transfer reaction as can be followed by spectrophotometry. Besides radical transfer reactions β-fragmentation reactions occur causing chain scission. Such reactions can be followed in a pulse radiolysis experiment by conductometry, because counter ions are released upon chain scission. Such a process is especially effective in the case of polymethacrylic acid, where it results in a chain depolymerization. An intramolecular H-abstraction is also observed in the γ-radiolysis of polyacrylic acid with the corresponding peroxyl radicals. This causes a chain reaction to occur. The resulting hydroperoxides are unstable and decarboxylate given rise to acetylacetone-like products. In polyvinyl alcohol the peroxyl radicals in α-position to the alcohol function undergo HO 2 -elimination. This prevents a scission of the polymer chain in the

  8. Free radical reactions of daunorubicin

    International Nuclear Information System (INIS)

    Houee-Levin, C.

    1991-01-01

    Daunorubicin is an antitumor antibiotic activated in vivo by reduction. Its mechanism of action involves DNA and topoisomerase attack, but side effects are cytotoxicity related to free radical formation. Therefore the mechanism of the one-electron reduction of the drug and the reactions of the daunorubicin transients towards compounds of biological interest have been studied by the methods of radiolysis, in order to provide possible explanations of the drug mechanism of action. Their relative importance in cellular conditions is discussed [fr

  9. Effects of the peculiar compositions in tea plant on free radicals induced by radiation

    International Nuclear Information System (INIS)

    Yang Yuehua; Lin Shuqi; Sun Tao; Cheng Qikun

    1994-01-01

    Effects of the peculiar compositions in tea plant on free radicals induced by radiation was investigated. Results showed that the contents of free radicals in aborescence large-leaf varieties were more than that in shrubby middle-small leaf varieties under the same irradiation dose. Dose-effect curve for free radical contents in tea varieties could be described with an exponential equation. The contents of free radical and the radiosensitivities were related to the contents of catechin, tea polyphenols, flavone glycoside and caffeine. The main factor that affected free radical content in tea plant was catechin. Results also showed that there was a quantitative effect between (-)-EGCG and free radical: (-)-EGCG could induce the increase of free radical contents in tea at low concentration but scavenge free radicals at high concentration

  10. Free radicals in chemical carcinogenesis.

    Science.gov (United States)

    Clemens, M R

    1991-12-15

    During the past decade, remarkable progress has been made in our understanding of cancer-causing agents, mechanisms of cancer formation and the behavior of cancer cells. Cancer is characterized primarily by an increase in the number of abnormal cells derived from a given normal tissue, invasion of adjacent tissues by these abnormal cells, and lymphatic or blood-borne spread of malignant cells to regional lymph nodes and to distant sites (metastasis). It has been estimated that about 75-80% of all human cancers are environmentally induced, 30-40% of them by diet. Only a small minority, possibly no more than 2% of all cases, result purely from inherent genetic changes. Several lines of evidence confirm that the fundamental molecular event or events that cause a cell to become malignant occur at the level of the DNA and a variety of studies indicate that the critical molecular event in chemical carcinogenesis is the interaction of the chemical agent with DNA. The demonstration that DNA isolated from tumor cells can transfect normal cells and render them neoplastic provides direct proof that an alteration of the DNA is responsible for cancer. The transforming genes, or oncogenes, have been identified by restriction endonuclease mapping. One of the characteristics of tumor cells generated by transformation with viruses, chemicals, or radiation is their reduced requirement for serum growth factors. A critical significance of electrophilic metabolites of carcinogenes in chemical carcinogenesis has been demonstrated. A number of "proximate" and "ultimate" metabolites, especially those of aromatic amines, were described. The "ultimate" forms of carcinogens actually interact with cellular constituents to cause neoplastic transformation and are the final metabolic products in most pathways. Recent evidence indicates that free radical derivatives of chemical carcinogens may be produced both metabolically and nonenzymatically during their metabolism. Free radicals carry no

  11. Effects of treatment on free radicals in patients with pulmonary ...

    African Journals Online (AJOL)

    fense against Mycobacteria, enhanced ROS generation may promote tissue injury .... time of analysis for electrolytes and free radicals. The sputum of patients .... with high level INH resistance in MTB by using real time technology PCR with 3 ...

  12. Free radicals in health and disease

    International Nuclear Information System (INIS)

    Gonet, B.

    1993-01-01

    Free radicals appear in the cells as the result of exogenic factors (ionizing radiation, UV) or reactions naturally occurring in the cell. Free radical reactions may cause destruction of macromolecules (DNA, lipids, proteins). Free radical pathology is important in many diseases and aging processes in organisms

  13. Oxygen free radicals in rheumatoid arthritis

    NARCIS (Netherlands)

    P. Biemond (Pieter)

    1986-01-01

    textabstractCurrent knowledge strongly suggests that oxygen free radicals are involved in the pathogenesis of RA. Additional information about the mechanism of free radical attack is necessary in order to find out if interaction with the mechanism of free radical damage can be used in the treatment

  14. Redox properties of free radicals

    International Nuclear Information System (INIS)

    Neta, P.

    1981-01-01

    Results of electron transfer reactions observed and monitored by pulse radiolysis are reported. This technique allows determination of the first one-electron reduction or oxidation of a compound rather than the overall two-electron transfer usually reported. Pulse radiolysis allows the determination of absolute rate constants for reactions of free radicals and helps elucidate the mechanisms involved. Studies using this technique to study radicals derived from quinones, nitro compounds, pyridines, phenols, and anilines are reported. Radicals of biochemical interest arising from riboflavin, ascorbic acid, vitamin K 3 , vitamin E, MAD + , porphyrins, etc. have also been studied

  15. Covalent Modification of Highly Ordered Pyrolytic Graphite with a Stable Organic Free Radical by Using Diazonium Chemistry.

    Science.gov (United States)

    Seber, Gonca; Rudnev, Alexander V; Droghetti, Andrea; Rungger, Ivan; Veciana, Jaume; Mas-Torrent, Marta; Rovira, Concepció; Crivillers, Núria

    2017-01-26

    A novel, persistent, electrochemically active perchlorinated triphenylmethyl (PTM) radical with a diazonium functionality has been covalently attached to highly ordered pyrolytic graphite (HOPG) by electrografting in a single-step process. Electrochemical scanning tunneling microscopy (EC-STM) and Raman spectroscopy measurements revealed that PTM molecules had a higher tendency to covalently react at the HOPG step edges. The cross-section profiles from EC-STM images showed that there was current enhancement at the functionalized areas, which could be explained by redox-mediated electron tunneling through surface-confined redox-active molecules. Cyclic voltammetry clearly demonstrated that the intrinsic properties of the organic radical were preserved upon grafting and DFT calculations also revealed that the magnetic character of the PTM radical was preserved. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Measurement of OH free radical in magnetized sheet plasma crossed with vertical gas-flow by laser-induced fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Tonegawa, Akira; Takatori, Masahiko; Kobayashi, Yukihiro; Kawamura, Kazutaka; Takayama, Kazuo

    1997-01-01

    We demonstrated the production of OH free radicals in an argon magnetized sheet plasma crossed with vertical gas-flow mixed with an oxygen gas O 2 and a hydrogen gas H 2 . The density and the rotational-vibrational temperature of the OH free radicals were measured by a laser-induced fluorescence (LIF). The density of OH free radicals increases with increasing O 2 gas-flow, while the high energy part of the electron-energy-distribution-function f e (E) above 8 eV decreases. These results suggest the high energy part of f e (E) is contributed to the dissociation of O 2 and the production of OH free radicals. (author)

  17. Nitroxyl free radicals formed from hindered amine light stabilizers under 60Co γ-ray irradiation

    International Nuclear Information System (INIS)

    Wang Huiliang; Chen Wenxiu

    2006-01-01

    Nitroxyl free radicals formed from several low molecular weight (LMW) hindered amine light stabilizers (HALS) under 60 Co γ-ray irradiation was studied with electron spin resonance (ESR) spectroscopy. All the HALSs irradiated in air formed nitroxyl free radicals under irradiation in air. For most of the HALSs, concentration of the nitroxyl free radicals increased linearly and quickly with absorbed dose in 0-10 kGy range, but increased slowly, or even kept constant, with doses of greater than 10 kGy. Concentration of nitroxyl free radicals formed from LMW HALS was usually higher than high molecular weight HALS. Tetramethyl HALS was easier to form nitroxyl free radicals than pentamethyl HLAS. Concentration of nitroxyl free radicals formed from the samples irradiated in oxygen was about two times higher than that the samples irradiated in air. Mechanisms of the nitroxyl free radical formation from the γ-ray irradiated HALSs were was discussed. (authors)

  18. Processing of free radical damaged DNA bases

    International Nuclear Information System (INIS)

    Wallace, S.

    2003-01-01

    Free radicals produced during the radiolysis of water gives rise to a plethora of DNA damages including single strand breaks, sites of base loss and a wide variety of purine and pyrimidine base lesions. All these damages are processed in cells by base excision repair. The oxidative DNA glycosylases which catalyze the first step in the removal of a base damage during base excision repair evolved primarily to protect the cells from the deleterious mutagenic effects of single free radical-induced DNA lesions arising during oxidative metabolism. This is evidenced by the high spontaneous mutation rate in bacterial mutants lacking the oxidative DNA glycosylases. However, when a low LET photon transverses the DNA molecule, a burst of free radicals is produced during the radiolysis of water that leads to the formation of clustered damages in the DNA molecule, that are recognized by the oxidative DNA glycosylases. When substrates containing two closely opposed sugar damages or base and sugar damages are incubated with the oxidative DNA glycosylases in vitro, one strand is readily incised by the lyase activity of the DNA glycosylase. Whether or not the second strand is incised depends on the distance between the strand break resulting from the incised first strand and the remaining DNA lesion on the other strand. If the lesions are more than two or three base pairs apart, the second strand is readily cleaved by the DNA glycosylase, giving rise to a double strand break. Even if the entire base excision repair system is reconstituted in vitro, whether or not a double strand break ensues depends solely upon the ability of the DNA glycosylase to cleave the second strand. These data predicted that cells deficient in the oxidative DNA glycosylases would be radioresistant while those that overproduce an oxidative DNA glycosylase would be radiosensitive. This prediction was indeed borne in Escherichia coli that is, mutants lacking the oxidative DNA glycosylases are radioresistant

  19. Allylthioketone Mediated Free Radical Polymerization of Methacrylates

    Directory of Open Access Journals (Sweden)

    Feng Zhong

    2017-11-01

    Full Text Available By combination of high trapping free radical efficiency of the thioketone and resonance of the allylic radical, a new type of mediating agent, 1,3,3-triphenylprop-2-ene-1-thione (TPPT has been successfully synthesized, and then is used to study controlled free radical polymerization of methacrylates. Very stable TPPT radicals at the end of poly(methyl methacrylate (PMMA are detected in the polymerization of MMA using TPPT and AIBN as the control agent and initiator. The MALDI-TOF MS spectra are used to identify terminal groups of the resultant poly(glycidyl methacrylate (PGMA, and major component of the obtained polymer has the structure, (CH32(CNC-PGMA-C7H9O3. Chain extension reaction tests ascertain formation of the dead polymers during the polymer storage and purification process of the polymers. Owing to very slow fragmentation reaction of the TPPT-terminated polymethacrylate radical and addition reaction of this radical with a primary radical, the growing chain radicals are difficult to be regenerated, leading to an unobvious change of the molecular weight with monomer conversion. The molecular weights of polymers can be controlled by the ratios of monomer/initiator and TPPT/initiator. However, the first order kinetics of the polymerization and the polymers with narrow polydispersity are obtained, and these phenomena are discussed. This study provides useful information on how to design a better controlling agent.

  20. An Appreciation of Free Radical Chemistry

    Indian Academy of Sciences (India)

    ... Lecture Workshops · Refresher Courses · Symposia · Live Streaming. Home; Journals; Resonance – Journal of Science Education; Volume 10; Issue 9. An Appreciation of Free Radical Chemistry - 6. Experiments Involving Free Radicals. G Nagendrappa. Classroom Volume 10 Issue 9 September 2005 pp 79-84 ...

  1. Measurements of free radical in vitamin E-doped ultra-high molecular weight polyethylene: Dependence on materials processing and irradiation environments

    Energy Technology Data Exchange (ETDEWEB)

    Ridley, M.D. [Department of Physics, Biomaterials Research Laboratory, University of Memphis, 216 Manning Hall, Memphis, TN 38152 (United States); Jahan, M.S. [Department of Physics, Biomaterials Research Laboratory, University of Memphis, 216 Manning Hall, Memphis, TN 38152 (United States)], E-mail: mjahan@memphis.edu

    2007-12-15

    Ultra-high molecular weight polyethylene (UHMWPE), doped with vitamin E ({alpha}-tocopherol ({alpha}-T)), was irradiated with gamma rays in nitrogen (N{sub 2}) or air, and the resulting free radicals were detected in air using an electron spin resonance (ESR) technique. Two groups of samples were investigated. In one group, samples were prepared from blends of {alpha}-T (20 wt%) and UHMWPE powder (PPE-{alpha}-T) and, in the other, from compression molded blocks (CMPE-{alpha}-T). The CMPE-{alpha}-T blocks contained 0% (control), 0.5%, 1.0%, 10.0%, 15.0%, 20.0% and 25.0% {alpha}-T by weight. When irradiation was performed in air, the ESR spectrum of powder samples showed the presence of only vitamin E radical (tocopheroxyl, {alpha}-T-O{sup {center_dot}}), and there was no detectable signal due to PE radicals (alkyl/allyl). Most likely, all PE radicals were quenched by vitamin E during irradiation in air. However, when irradiation was performed in N{sub 2}, composite ESR spectra showed the presence of both PE and {alpha}-T-O{sup {center_dot}} radicals. Compared to the control (PPE, 0% {alpha}-T) PE radicals in PPE-20% {alpha}-T were found to be significantly reduced or quenched by {alpha}-T. The presence of {alpha}-T in powder samples, however, did not affect the long-term (71 days in this study) oxidation behavior of the PE radicals. Compression molded samples, with and without {alpha}-T, produced identical ESR spectra irrespective of their irradiation environment N{sub 2} or air. However, radical concentration, measured immediately after irradiation, was found to be an order of magnitude less in CMPE-{alpha}-T than in the control (CMPE-0% {alpha}-T). They also evidenced identical structural changes in the respective ESR spectra during subsequent oxidation for 24 days in open air. These observations suggest that {alpha}-T can effectively quench a significant fraction of PE radicals during irradiation, but has no measurable effect on subsequent reactions. No

  2. Fast beam studies of free radical photodissociation

    Energy Technology Data Exchange (ETDEWEB)

    Neumark, D.M. [Lawrence Berkeley Laboratory, CA (United States)

    1993-12-01

    The authors have developed a novel technique for studying the photodissociation spectroscopy and dynamics of free radicals. In these experiments, radicals are generated by laser photodetachment of a fast (6-8 keV) mass-selected negative ion beam. The resulting radicals are photodissociated with a second laser, and the photofragments are collected and detected with high efficiency using a microchannel plate detector. The overall process is: ABC{sup -} {yields} ABC + e{sup -} {yields} A + BC, AB + C. Two types of fragment detection schemes are used. To map out the photodissociation cross-section of the radical, the photodissociation laser is scanned and the total photofragment yield is measured as a function of wavelength. In other experiments, the photodissociation frequency is fixed and the photofragment masses, kinetic energy release, and scattering angle is determined for each photodissociation event.

  3. MISCONCEPTIONS AND NON-SCIENTIFIC CONCEPTS ON FREE RADICALS

    Directory of Open Access Journals (Sweden)

    Rosiris Sindeaux de Alencar Pires de Oliveira

    2016-11-01

    Full Text Available INTRODUCTION: Misconceptions or alternative conceptions are defined as conceptions that are somewhat different from the scientifically accepted ones and are known to be highly resistant to changes. Free radicals are a widely publicized subject in the media due to their putative importance in human aging and health. Free radicals are a subject susceptible to misconceptions widely spread by the media supporting prejudicial advertising inducing antioxidant consumption. OBJECTIVES: Identify and categorized different free radicals misconceptions published in printed media. MATERIALS AND METHODS: Revista Veja (Digital Archive, the weekly magazine with the largest circulation in Brazil, was selected for this investigation. Period analyzed: from 01/01/2000 to 31/07/2014 with search terms Free radicals and antioxidants. Passages selected were classified as: Right Concept (RC, Wrong Concept (WC, Misconception (MC, Inadequate generalization (IG, Inductive [to misconceptions] Concept (IC, Inductive [to misconceptions] Information (II, and Not fit the inclusion criteria (NFIC. Each one of these categories were further subdivided. DISCUSSION AND RESULTS: 79 magazine articles, advertisements and information materials were found which led to 293 text passages. 56.3% were MC, 21.4% II, 8.8% IC, 5.4% IG, 3.4% RC, 2.7% WR, 2.0% NFIC. The most frequently subcategory in each category was: MC: x [something] combats free radicals (22.6%; II: x [substance] is antioxidant (54.0%; IC: x [something] increases free radicals production (34.6%; IG: antioxidant x [substance] combats cancer (56.3%; RC: too much vitamins and minerals is harmful to health (30.0%; WR: free radicals are formed during oxygen conversion to energy process (25.0%. CONCLUSION: Magazine analysis reveal non-scientific concepts (MC, II, IC and IG to be highly frequent, notably misconceptions. Moreover, non-scientific concepts together reach 91.8% of all concepts while right concepts respond for only 2

  4. Free radical EPR in delineating oil bearing zones

    International Nuclear Information System (INIS)

    Sharma, R.K.; Kumar, V.; Das, T.K.; Gundu Rao, T.K.

    1993-01-01

    Presence of naturally occurring gamma ray activity has long been detected in oil/gas wells is invariably carried out for formation evaluation. Similarly, presence of free radicals in oil bearing formations has also been known for quite sometime. Present paper deals with a systematic study of detecting these free radicals in oil wells and correlations of these with x-ray and other logs for identification of hydrocarbon bearing zones. Present study attempts to establish EPR as as inexpensive and reliable tool in comparison with gamma ray and neutron density logs recorded in exploratory oil wells. EPR studies have been carried out in an exploratory well between depth intervals 1600 m-1400 m located in south of existing producing field in Bombay Offshore region. Based on these results, an EPR log has been prepared and compared with gamma ray and neutron density logs. (author). 4 refs., 1 fig., 1 tab

  5. Free radicals trapped in polyethylene matrix

    International Nuclear Information System (INIS)

    Shimada, S.; Maeda, M.; Hori, Y.; Kashiwabara, H.

    1977-01-01

    Two types of alkyl radicals were found to be trapped in irradiated crystals grown from polyethylene solution. One of them corresponds to the broad sextet pattern of the e.s.r. spectrum and the other corresponds to the sharp sextet pattern. The free radicals attributed to the broad sextet began to disappear at a lower temperature than the temperature at which the free radicals attributed to the sharp sextet disappeared. When butadiene molecules were brought into contact with the specimen, the decay of the free radicals corresponding to the broad sextet was accelerated. When the specimen was subjected to fuming nitric acid treatment, no broad sextet was observed. The mat of the crystals was aligned so that the c-axes of its crystallites were perpendicular to its surface. The broad sextet showed no anisotropy when the angle between the direction of applied magnetic field and that of the c-axis of the crystallite was varied. On the other hand, the sharp component of the spectrum showed apparent anisotropy. It can be concluded that the broad component comes from the free radicals trapped in the lamellar surface and the sharp component is attributed to the free radicals trapped in the inner part of the crystallite. (author)

  6. Unconventional field induced phases in a quantum magnet formed by free radical tetramers

    Science.gov (United States)

    Saúl, Andrés; Gauthier, Nicolas; Askari, Reza Moosavi; Côté, Michel; Maris, Thierry; Reber, Christian; Lannes, Anthony; Luneau, Dominique; Nicklas, Michael; Law, Joseph M.; Green, Elizabeth Lauren; Wosnitza, Jochen; Bianchi, Andrea Daniele; Feiguin, Adrian

    2018-02-01

    We report experimental and theoretical studies on the magnetic and thermodynamic properties of NIT-2Py, a free radical based organic magnet. From magnetization and specific-heat measurements we establish the temperature versus magnetic field phase diagram which includes two Bose-Einstein condensates (BEC) and an infrequent half-magnetization plateau. Calculations based on density functional theory demonstrate that magnetically this system can be mapped to a quasi-two-dimensional structure of weakly coupled tetramers. Density matrix renormalization group calculations show the unusual characteristics of the BECs where the spins forming the low-field condensate are different than those participating in the high-field one.

  7. Free radical scavenging and COX-2 inhibition by simple colon metabolites of polyphenols: A theoretical approach.

    Science.gov (United States)

    Amić, Ana; Marković, Zoran; Marković, Jasmina M Dimitrić; Jeremić, Svetlana; Lučić, Bono; Amić, Dragan

    2016-12-01

    Free radical scavenging and inhibitory potency against cyclooxygenase-2 (COX-2) by two abundant colon metabolites of polyphenols, i.e., 3-hydroxyphenylacetic acid (3-HPAA) and 4-hydroxyphenylpropionic acid (4-HPPA) were theoretically studied. Different free radical scavenging mechanisms are investigated in water and pentyl ethanoate as a solvent. By considering electronic properties of scavenged free radicals, hydrogen atom transfer (HAT) and sequential proton loss electron transfer (SPLET) mechanisms are found to be thermodynamically probable and competitive processes in both media. The Gibbs free energy change for reaction of inactivation of free radicals indicates 3-HPAA and 4-HPPA as potent scavengers. Their reactivity toward free radicals was predicted to decrease as follows: hydroxyl>alkoxyls>phenoxyl≈peroxyls>superoxide. Shown free radical scavenging potency of 3-HPAA and 4-HPPA along with their high μM concentration produced by microbial colon degradation of polyphenols could enable at least in situ inactivation of free radicals. Docking analysis with structural forms of 3-HPAA and 4-HPPA indicates dianionic ligands as potent inhibitors of COX-2, an inducible enzyme involved in colon carcinogenesis. Obtained results suggest that suppressing levels of free radicals and COX-2 could be achieved by 3-HPAA and 4-HPPA indicating that these compounds may contribute to reduced risk of colon cancer development. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Fast beam studies of free radical photodissociation

    Energy Technology Data Exchange (ETDEWEB)

    Cyr, Douglas Robert [Univ. of California, Berkeley, CA (United States)

    1993-11-01

    The photodissociation of free radicals is studied in order to characterize the spectroscopy and dissociation dynamics of the dissociative electronic states in these species. To accomplish this, a novel method of radical production, based on the photodetachment of the corresponding negative ion, has been combined with a highly complementary form of photofragment translational spectroscopy. The optical spectroscopy of transitions to dissociative states is determined by monitoring the total photofragment yield as a function of dissociation photon energy. Branching ratios to various product channels, internal energy distributions of the fragments, bond dissociation energies, and the translational energy-dependent photofragment recoil angular distributions are then determined at selected excitation energies. A detailed picture of the dissociation dynamics can then be formulated, allowing insight concerning the interactions of potential energy surfaces involved in the dissociation. After an introduction to the concepts and techniques mentioned above, the experimental apparatus used in these experiments is described in detail. The basis and methods used in the treatment of data, especially in the dissociation dynamics experiments, are then put forward.

  9. Fast beam studies of free radical photodissociation

    International Nuclear Information System (INIS)

    Cyr, D.R.; California Univ., Berkeley, CA

    1993-11-01

    The photodissociation of free radicals is studied in order to characterize the spectroscopy and dissociation dynamics of the dissociative electronic states in these species. To accomplish this, a novel method of radical production, based on the photodetachment of the corresponding negative ion, has been combined with a highly complementary form of photofragment translational spectroscopy. The optical spectroscopy of transitions to dissociative states is determined by monitoring the total photofragment yield as a function of dissociation photon energy. Branching ratios to various product channels, internal energy distributions of the fragments, bond dissociation energies, and the translational energy-dependent photofragment recoil angular distributions are then determined at selected excitation energies. A detailed picture of the dissociation dynamics can then be formulated, allowing insight concerning the interactions of potential energy surfaces involved in the dissociation. After an introduction to the concepts and techniques mentioned above, the experimental apparatus used in these experiments is described in detail. The basis and methods used in the treatment of data, especially in the dissociation dynamics experiments, are then put forward

  10. ESR study on free radicals trapped in crosslinked polytetrafluoroethylene (PTFE)

    International Nuclear Information System (INIS)

    Oshima, Akihiro; Tabata, Yoneho; Seguchi, Tadao

    1997-01-01

    Free radicals in crosslinked PTFE which formed by 60 Co γ-rays irradiation at 77 K and at room temperature were studied by electron spin resonance (ESR) spectroscopy. The crosslinked PTFE specimens with different crosslinking density were prepared by electron beam irradiation in the molten state. The ESR spectra observed in the irradiated crosslinked PTFE are much different from those in non-crosslinked PTFE (virgin); a broad singlet component increases with increasing the crosslinking density, G-value of radicals is much higher in crosslinked PTFE than in non-crosslinked one. Free radicals related to the broad component are trapped in the non-crystalline region of crosslinked PTFE and rather stable at room temperature, whereas radicals trapped in amorphous non-crosslinked PTFE are unstable at room temperature. It is thought that most of free radicals trapped in the crosslinked PTFE are formed in the crosslinked amorphous region. The trapped radicals decays around 383 K (110 o C) due to the molecular motion of α-relaxation. (Author)

  11. Free radicals in biology. Volume II

    International Nuclear Information System (INIS)

    Pryor, W.A.

    1976-01-01

    This volume continues the treatment of topics in free radical biology and free radical pathology from Volume I. In the first chapter, pyridinyl radicals, radicals which are models for those derived from NAD, are discussed. Pyridinyl radicals can be synthesized and isolated and directly studied in a number of chemical systems. The next chapter treats the role of glutathione in the cell. It is becoming even more apparent that this vital thiol controls a large number of important cellular functions. The GSH/GSSG balance has recently been implicated as a control for cellular development; this balance also may be important in relaying the effects of oxidants from one site to another in the body. The next chapter outlines the reactions of singlet oxygen; some of these involve free radicals and some do not. This reactive intermediate appears to be important both in photochemical smog and in cellular chemistry where singlet oxygen is produced by nonphotochemical processes. The production of free radicals from dry tissues, a controversial area with conflicting claims is reviewed. The next chapter outlines the current status of the studies of photochemical smog. The next two chapters treat specific reactive materials which are present in smog. The first discusses the chemistry of nitrogen oxides and ozone. The second chapter treats the chemistry of the peroxyacyl nitrites. These compounds, although present in only small concentration, are among the most toxic components of smog. The last two chapters treat radiation damage to proteins and radiation protection and radical reactions produced by radiation in nucleic acids

  12. Lipophilic fluorescent products of free radicals

    Czech Academy of Sciences Publication Activity Database

    Ivica, Josko; Wilhelm, Jiří

    2014-01-01

    Roč. 158, č. 3 (2014), s. 365-372 ISSN 1213-8118 R&D Projects: GA ČR(CZ) GAP303/11/0298 Institutional support: RVO:67985823 Keywords : lipofuscin-like pigments * lipid peroxidation * free radical s * fluorescence Subject RIV: CE - Biochemistry Impact factor: 1.200, year: 2014

  13. Phytochemical screening, free radical scavenging and antibacterial ...

    African Journals Online (AJOL)

    Cassia sieberiana is a tropical plant, widely distributed throughout Sudan and Guinea savannah. It is used in traditional medicine for the treatment of malarial, cancer and stomach ache. The study was conducted to screen for phytochemicals, free radical scavenging and antibacterial potentials of the root bark.

  14. The role of proteins in damage induced by free radicals

    International Nuclear Information System (INIS)

    Gebicki, J.M.

    1996-01-01

    The initial consequence of oxidative stress in living organisms is chemical modification of cell components. Recently increasing attention in this area has been paid to the modification of proteins. A form of protein modification which has been studied in some detail only recently is peroxidation. In the last 8 years, we and our collaborators have shown that a range of isolated proteins acquire hydroperoxide groups when exposed to a range of biologically plausible oxidants. These include HO free radicals generated by radiation or in the Fenton reaction, peroxyl radicals, oxidants released by activated neutrophils, and peroxynitrite. In more complex systems, we also found protein peroxides in the apo B component of LDL treated with 20 μM Cu ++ , and in irradiated blood serum. These observations suggest that the formation of protein peroxides is a possible consequence of oxidative stress in vivo. A remarkable feature of the process of protein peroxidation is its high efficiency. This is most easily measured with proteins oxidized by radiation-generated free radicals. It was found that, for some proteins, peroxide yields reached 40% of the numbers of HO radicals generated. Thus in effect, almost half of these radicals can be converted to the much more long-lived protein peroxide groups. If they, in turn, have the capacity to damage other molecules, the major oxidative pathway in vivo may have the sequence: free radical ? protein peroxide ? another oxidized molecule. This hypothesis was tested by studying the ability of protein peroxides to react with selected molecules and the results are briefly discussed. Clearly, these effects are specific to individual proteins. More generally, amino acid and protein peroxides were found to be a potential source of a range of free radicals when reduced by Fe ++ . If this turns out to be a common phenomenon, protein peroxides may prove to be a major source of oxidative damage

  15. The role of proteins in damage induced by free radicals

    Energy Technology Data Exchange (ETDEWEB)

    Gebicki, J.M. [Macquarie Univ., North Ryde, NSW (Australia). School of Biological Sciences

    1996-12-31

    The initial consequence of oxidative stress in living organisms is chemical modification of cell components. Recently increasing attention in this area has been paid to the modification of proteins. A form of protein modification which has been studied in some detail only recently is peroxidation. In the last 8 years, we and our collaborators have shown that a range of isolated proteins acquire hydroperoxide groups when exposed to a range of biologically plausible oxidants. These include HO free radicals generated by radiation or in the Fenton reaction, peroxyl radicals, oxidants released by activated neutrophils, and peroxynitrite. In more complex systems, we also found protein peroxides in the apo B component of LDL treated with 20 {mu}M Cu{sup ++}, and in irradiated blood serum. These observations suggest that the formation of protein peroxides is a possible consequence of oxidative stress in vivo. A remarkable feature of the process of protein peroxidation is its high efficiency. This is most easily measured with proteins oxidized by radiation-generated free radicals. It was found that, for some proteins, peroxide yields reached 40% of the numbers of HO radicals generated. Thus in effect, almost half of these radicals can be converted to the much more long-lived protein peroxide groups. If they, in turn, have the capacity to damage other molecules, the major oxidative pathway in vivo may have the sequence: free radical ? protein peroxide ? another oxidized molecule. This hypothesis was tested by studying the ability of protein peroxides to react with selected molecules and the results are briefly discussed. Clearly, these effects are specific to individual proteins. More generally, amino acid and protein peroxides were found to be a potential source of a range of free radicals when reduced by Fe{sup ++}. If this turns out to be a common phenomenon, protein peroxides may prove to be a major source of oxidative damage.

  16. Computational study of the structure-free radical scavenging relationship of procyanidins.

    Science.gov (United States)

    Mendoza-Wilson, Ana María; Castro-Arredondo, Sergio Ivan; Balandrán-Quintana, René Renato

    2014-10-15

    Procyanidins (PCs) are effective free radical scavengers, however, their antioxidant ability is variable because they have different degrees of polymerisation, are composed by distinct types of subunits and are very susceptible to changes in conformation. In this work the structure-free radical scavenging relationship of monomers, dimers and trimers of PCs was studied through the hydrogen atom transfer (HAT), sequential proton-loss electron-transfer (SPLET) and single electron transfer followed by proton transfer (SET-PT) mechanisms in aqueous phase, employing the Density Functional Theory (DFT) computational method. The structure-free radical scavenging relationship of PCs showed a very similar behaviour in HAT and SET-PT mechanisms, but very different in the SPLET mechanism. The structural factor that showed more effects on the ability of PCs to scavenge free radicals in aqueous phase was the conformation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. EPR study of free radicals in bread

    Science.gov (United States)

    Yordanov, Nicola D.; Mladenova, Ralitsa

    2004-05-01

    The features of the recorded EPR spectra of paramagnetic species formed in bread and rusk are reported. The appearance of free radicals in them is only connected with their thermal treatment since the starting materials (flour and grains) exhibit very weak EPR signal. The obtained EPR spectra are complex and indicate that: (i) the relative number of paramagnetic species depends on the temperature and treating time of the raw product; (ii) the g-values are strongly temperature dependent with a tendency to coincide at t≥220 °C. Because of the relatively low (150-220 °C) temperature of thermal treatment, the studied free radicals can be assumed to appear in the course of the browning (Maillard) reaction and not to the carbonization of the material.

  18. Mechanisms of free radical-induced damage to DNA.

    Science.gov (United States)

    Dizdaroglu, Miral; Jaruga, Pawel

    2012-04-01

    Endogenous and exogenous sources cause free radical-induced DNA damage in living organisms by a variety of mechanisms. The highly reactive hydroxyl radical reacts with the heterocyclic DNA bases and the sugar moiety near or at diffusion-controlled rates. Hydrated electron and H atom also add to the heterocyclic bases. These reactions lead to adduct radicals, further reactions of which yield numerous products. These include DNA base and sugar products, single- and double-strand breaks, 8,5'-cyclopurine-2'-deoxynucleosides, tandem lesions, clustered sites and DNA-protein cross-links. Reaction conditions and the presence or absence of oxygen profoundly affect the types and yields of the products. There is mounting evidence for an important role of free radical-induced DNA damage in the etiology of numerous diseases including cancer. Further understanding of mechanisms of free radical-induced DNA damage, and cellular repair and biological consequences of DNA damage products will be of outmost importance for disease prevention and treatment.

  19. EPR and optical spectroscopic studies of neutral free radicals in an adamantane matrix

    International Nuclear Information System (INIS)

    Jordan, J.E.

    1975-03-01

    Recent work in our laboratory has demonstrated that neutral free radicals produced by x-irradiation and trapped in adamantane exhibit exceedingly long lifetimes because of the lack of rapid diffusion in the solid matrix. This observation and the fact that samples can be pressed into pellets with high optical transparency in the visible and near uv regions of the spectrum suggested to us that this unique matrix might be used for studying the optical properties of free radicals. The results of a wide variety of experiments of this type are described in this thesis. These include experiments in which secondary free radicals are produced by photoinduced decomposition of primary free radicals by selective irradiation with visible light, the observation of strong optical absorption spectra of free radicals at room temperature using a Cary 14 spectrophotometer, the finding that certain free radicals exhibit strong, visible fluorescence when irradiated with uv light, and the discovery that the absorption intensity of multiplicity-forbidden transition in singlet and doublet state species is enhanced relative to spin-allowed transitions by at least three orders of magnitude. An analysis of these results in terms of molecular orbital theory is given, and experiments designed to obtain the epr spectra of electronically-excited states of free radicals are described

  20. Free radicals induced archive paper by irradiation

    International Nuclear Information System (INIS)

    Cutrubinis, M.; Moise, I.V.; Negut, C.D.; Georgescu, R.; Suvaila, R.; Virgolici, M.; Manea, M.M.

    2011-01-01

    Complete text of publication follows. Irradiation of archive paper (document archives of institutions, companies etc. and library or museum collections of books and documents) can solve the problems related to the bio-deterioration and bio-contamination of paper and sometimes save valuable cultural heritage paper items. For valuable paper items care should be taken to the degradation induced instantly by the ionising radiation to the cellulosic support and also to the long term post-irradiation effects. The free radicals formed due to the irradiation treatment could contribute to instant degradation of paper. Part of them are also trapped for months and years after irradiation and they could be related to the post-irradiation effects in paper items. In this study, different sorts of cellulosic support samples (soft wood and hard wood cellulose, contemporary paper, paper from archives and from collections etc.) have been irradiated with dosis up to 100 kGy and the radiation induced free radicals have been measured by ESR spectrometry. The ESR signals have shown the type and quantity of radiation induced free radicals. Their study can be used for a realistic estimation of the degradative effect of the ionising radiation treatment of archive paper.

  1. Isoflurane preconditions myocardium against infarction via release of free radicals

    NARCIS (Netherlands)

    Müllenheim, Jost; Ebel, Dirk; Frässdorf, Jan; Preckel, Benedikt; Thämer, Volker; Schlack, Wolfgang

    2002-01-01

    BACKGROUND: Isoflurane exerts cardioprotective effects that mimic the ischemic preconditioning phenomenon. Generation of free radicals is implicated in ischemic preconditioning. The authors investigated whether isoflurane-induced preconditioning may involve release of free radicals. METHODS:

  2. Scavenging performance and antioxidant activity of γ-alumina nanoparticles towards DPPH free radical: Spectroscopic and DFT-D studies.

    Science.gov (United States)

    Zamani, Mehdi; Moradi Delfani, Ali; Jabbari, Morteza

    2018-05-03

    The radical scavenging performance and antioxidant activity of γ-alumina nanoparticles towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical were investigated by spectroscopic and computational methods. The radical scavenging ability of γ-alumina nanoparticles in the media with different polarity (i.e. i-propanol and n-hexane) was evaluated by measuring the DPPH absorbance in UV-Vis absorption spectra. The structure and morphology of γ-alumina nanoparticles before and after adsorption of DPPH were studied using XRD, FT-IR and UV-Vis spectroscopic techniques. The adsorption of DPPH free radical on the clean and hydrated γ-alumina (1 1 0) surface was examined by dispersion corrected density functional theory (DFT-D) and natural bond orbital (NBO) calculations. Also, time-dependent density functional theory (TD-DFT) was used to predict the absorption spectra. The adsorption was occurred through the interaction of radical nitrogen N and NO 2 groups of DPPH with the acidic and basic sites of γ-alumina surface. The high potential for the adsorption of DPPH radical on γ-alumina nanoparticles was investigated. Interaction of DPPH with Brønsted and Lewis acidic sites of γ-alumina was more favored than Brønsted basic sites. The following order for the adsorption of DPPH over the different active sites of γ-alumina was predicted: Brønsted base free radicals. Copyright © 2018. Published by Elsevier B.V.

  3. Free radicals in wood induced by γ-radiation

    International Nuclear Information System (INIS)

    Xu Honglin; Zhang Wenhui

    1994-01-01

    The free radicals in wood induced by γ-radiation were studied by electron spin resonance. The fine structure of the ESR signal from sawdust samples irradiated could be resolved into various radicals. These free radicals have a very long lifetime. The major spectrum for the free radicals will exponentially increased along with the radiation dose according to Y 1-Exp(-α a D). The intensity of radiation radicals is dependent on tree species. The stronger the intensity of mechanic free radicals is, the stronger the intensity of radiation free radicals

  4. Hydroxyl free radical production during torsional phacoemulsification.

    Science.gov (United States)

    Aust, Steven D; Hebdon, Thomas; Humbert, Jordan; Dimalanta, Ramon

    2010-12-01

    To quantitate free radical generation during phacoemulsification using an ultrasonic phacoemulsification device that includes a torsional mode and evaluate tip designs specific to the torsional mode. Chemistry and Biochemistry Department, Utah State University, Logan, Utah, USA. Experimental study. Experiments were performed using the Infiniti Vision System and OZil handpiece. Hydroxyl radical concentrations in the aspirated irrigation solution during torsional phacoemulsification were quantitated as nanomolar malondialdehyde (nM MDA) and determined spectrophotometrically using the deoxyribose assay. The mean free radical production during phacoemulsification with torsional modality at 100% amplitude was 30.1 nM MDA ± 5.1 (SD) using a 0.9 mm 45-degree Kelman tapered ABS tip. With other tip designs intended for use with the torsional modality, free radical production was further reduced when fitted with the 0.9 mm 45-degree Kelman mini-flared ABS tip (13.2 ± 5.6 nM MDA) or the 0.9 mm 45-degree OZil-12 mini-flared ABS tip (14.3 ± 6.7 nM MDA). Although the measurements resulting from the use of the latter 2 tips were not statistically significantly different (P ≈ .25), they were different from those of the tapered tip (P<.0001). The MDA concentration in the aspirated irrigation solution using the torsional modality was approximately one half that reported for the handpiece's longitudinal modality in a previous study using the same bent-tip design (Kelman tapered, P<.0001). The level of MDA was further reduced approximately one half with torsional-specific tips. Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  5. Effects of Solvent and Temperature on Free Radical Formation in Electronic Cigarette Aerosols.

    Science.gov (United States)

    Bitzer, Zachary T; Goel, Reema; Reilly, Samantha M; Foulds, Jonathan; Muscat, Joshua; Elias, Ryan J; Richie, John P

    2018-01-16

    The ever-evolving market of electronic cigarettes (e-cigarettes) presents a challenge for analyzing and characterizing the harmful products they can produce. Earlier we reported that e-cigarette aerosols can deliver high levels of reactive free radicals; however, there are few data characterizing the production of these potentially harmful oxidants. Thus, we have performed a detailed analysis of the different parameters affecting the production of free radical by e-cigarettes. Using a temperature-controlled e-cigarette device and a novel mechanism for reliably simulating e-cigarette usage conditions, including coil activation and puff flow, we analyzed the effects of temperature, wattage, and e-liquid solvent composition of propylene glycol (PG) and glycerol (GLY) on radical production. Free radicals in e-cigarette aerosols were spin-trapped and analyzed using electron paramagnetic resonance. Free radical production increased in a temperature-dependent manner, showing a nearly 2-fold increase between 100 and 300 °C under constant-temperature conditions. Free radical production under constant wattage showed an even greater increase when going from 10 to 50 W due, in part, to higher coil temperatures compared to constant-temperature conditions. The e-liquid PG content also heavily influenced free radical production, showing a nearly 3-fold increase upon comparison of ratios of 0:100 (PG:GLY) and 100:0 (PG:GLY). Increases in PG content were also associated with increases in aerosol-induced oxidation of biologically relevant lipids. These results demonstrate that the production of reactive free radicals in e-cigarette aerosols is highly solvent dependent and increases with an increase in temperature. Radical production was somewhat dependent on aerosol production at higher temperatures; however, disproportionately high levels of free radicals were observed at ≥100 °C despite limited aerosol production. Overall, these findings suggest that e-cigarettes can be

  6. The mitochondrial free radical theory of aging.

    Science.gov (United States)

    Barja, Gustavo

    2014-01-01

    The mitochondrial free radical theory of aging is reviewed. Only two parameters currently correlate with species longevity in the right sense: the mitochondrial rate of reactive oxygen species (mitROS) production and the degree of fatty acid unsaturation of tissue membranes. Both are low in long-lived animals. In addition, the best-known manipulation that extends longevity, dietary restriction, also decreases the rate of mitROS production and oxidative damage to mtDNA. The same occurs during protein restriction as well as during methionine restriction. These two manipulations also increase maximum longevity in rodents. The decrease in mitROS generation and oxidative stress that takes place in caloric restriction seems to be due to restriction of a single dietary substance: methionine. The information available supports a mitochondrial free radical theory of aging focused on low generation of endogenous damage and low sensitivity of membranes to oxidation in long-lived animals. © 2014 Elsevier Inc. All rights reserved.

  7. Unimolecular reaction dynamics of free radicals

    International Nuclear Information System (INIS)

    Terry A. Miller

    2006-01-01

    Free radical reactions are of crucial importance in combustion and in atmospheric chemistry. Reliable theoretical models for predicting the rates and products of these reactions are required for modeling combustion and atmospheric chemistry systems. Unimolecular reactions frequently play a crucial role in determining final products. The dissociations of vinyl, CH2= CH, and methoxy, CH3O, have low barriers, about 13,000 cm-1 and 8,000 cm-1, respectively. Since barriers of this magnitude are typical of free radicals these molecules should serve as benchmarks for this important class of reactions. To achieve this goal, a detailed understanding of the vinyl and methoxy radicals is required. Results for dissociation dynamics of vinyl and selectively deuterated vinyl radical are reported. Significantly, H-atom scrambling is shown not to occur in this reaction. A large number of spectroscopic experiments for CH3O and CHD2O have been performed. Spectra recorded include laser induced fluorescence (LIF), laser excited dispersed fluorescence (LEDF), fluorescence dip infrared (FDIR) and stimulated emission pumping (SEP). Such results are critical for implementing dynamics experiments involving the dissociation of methoxy

  8. Effect of flavoring chemicals on free radical formation in electronic cigarette aerosols.

    Science.gov (United States)

    Bitzer, Zachary T; Goel, Reema; Reilly, Samantha M; Elias, Ryan J; Silakov, Alexey; Foulds, Jonathan; Muscat, Joshua; Richie, John P

    2018-05-20

    Flavoring chemicals, or flavorants, have been used in electronic cigarettes (e-cigarettes) since their inception; however, little is known about their toxicological effects. Free radicals present in e-cigarette aerosols have been shown to induce oxidative stress resulting in damage to proliferation, survival, and inflammation pathways in the cell. Aerosols generated from e-liquid solvents alone contain high levels of free radicals but few studies have looked at how these toxins are modulated by flavorants. We investigated the effects of different flavorants on free radical production in e-cigarette aerosols. Free radicals generated from 49 commercially available e-liquid flavors were captured and analyzed using electron paramagnetic resonance (EPR). The flavorant composition of each e-liquid was analyzed by gas chromatography mass spectroscopy (GCMS). Radical production was correlated with flavorant abundance. Ten compounds were identified and analyzed for their impact on free radical generation. Nearly half of the flavors modulated free radical generation. Flavorants with strong correlations included β-damascone, δ-tetradecalactone, γ-decalactone, citral, dipentene, ethyl maltol, ethyl vanillin, ethyl vanillin PG acetal, linalool, and piperonal. Dipentene, ethyl maltol, citral, linalool, and piperonal promoted radical formation in a concentration-dependent manner. Ethyl vanillin inhibited the radical formation in a concentration dependent manner. Free radical production was closely linked with the capacity to oxidize biologically-relevant lipids. Our results suggest that flavoring agents play an important role in either enhancing or inhibiting the production of free radicals in flavored e-cigarette aerosols. This information is important for developing regulatory strategies aimed at reducing potential harm from e-cigarettes. Copyright © 2018 Elsevier Inc. All rights reserved.

  9. Production of free radical by magnetized sheet plasma with vertical gas-flow

    International Nuclear Information System (INIS)

    Tonegawa, Akira; Takatori, Masahiko; Kawamura, Kazutaka

    1995-01-01

    Free radicals play an important role in plasma processing, environment problem, and space plasma and so on because of their outstanding physical properties. Although much work has been done on the free radicals in the reactive plasma, very little is known about the production mechanism of the free radicals against various plasma parameters. To overcome this problem, we have proposed to do a new system of a magnetized sheet plasma with vertical gas-flow. The sheet plasma is a special type of strongly magnetized highly ionized slab plasma. This system is controlled to the parameters of radicals and plasma independently. Therefore, it is possible to make a quantitative analysis of free radicals as the simple one. In this paper, we describe the magnetized sheet plasma with vertical gas-flow system and report the preliminary results of production of the free radical. In particular, we show to produce and control the OH free radical which has been the most commonly studied combustion species

  10. Infrared absorption spectroscopy and chemical kinetics of free radicals

    Energy Technology Data Exchange (ETDEWEB)

    Curl, R.F.; Glass, G.P. [Rice Univ., Houston, TX (United States)

    1993-12-01

    This research is directed at the detection, monitoring, and study of chemical kinetic behavior by infrared absorption spectroscopy of small free radical species thought to be important intermediates in combustion. During the last year, infrared kinetic spectroscopy using excimer laser flash photolysis and color-center laser probing has been employed to study the high resolution spectrum of HCCN, the rate constant of the reaction between ethynyl (C{sub 2}H) radical and H{sub 2} in the temperature region between 295 and 875 K, and the recombination rate of propargyl (CH{sub 2}CCH) at room temperature.

  11. Ab initio study of the Si(CH3)2O double free radical under external electric field

    International Nuclear Information System (INIS)

    Chen Xiaojun; Luo Sunzhong; Jiang Shubing; Huang Wei; Gao Xiaoling; Ma Meizhong; Zhu Zhenghe

    2004-01-01

    Infrared spectrum and NMR chemical shifts of Si(CH 3 ) 2 O double free radical were calculated employing density functional theory (DFT) with the basis sets 6-311 + G(2d, p). Excited states, dipole moment and energy of Si(CH 3 ) 2 O double free radical were also calculated using time dependent density function theory (TD-DFT) with the same basis sets. It is found that the external electric field along the X, Y and Z axis affect differently on the excited states and other properties of Si(CH 3 ) 2 O double free radical. (author)

  12. Resveratrol products resulting by free radical attack

    Energy Technology Data Exchange (ETDEWEB)

    Bader, Yvonne; Quint, R.M. [Section Radiation Biology, Department of Nutritional Sciences, Faculty of Life Sciences, University of Vienna, UZAII, Althanstrasse 14, A-1090 Vienna (Austria); Getoff, Nikola [Section Radiation Biology, Department of Nutritional Sciences, Faculty of Life Sciences, University of Vienna, UZAII, Althanstrasse 14, A-1090 Vienna (Austria)], E-mail: nikola.getoff@univie.ac.at

    2008-06-15

    Trans-resveratrol (trans-3,4',5-trihydroxystilbene; RES), which is contained in red wine and many plants, is one of the most relevant and extensively investigated stilbenes with a broad spectrum of biological activities. Among other duties, RES has been reported to have anti-carcinogenetic activities, which could be attributed to its antioxidant properties. The degradation of RES was studied under various conditions. The products (aldehydes, carboxylic acids, etc.) generated from RES by the attack of free radicals were registered as a function of the radical concentration (absorbed radiation dose). Based on the obtained data it appears that the OH radicals are initiating the rather complicated process, which involves of the numerous consecutive reactions. A possible starting reaction mechanism is presented.

  13. Effect of metal complexation to anti-inflammatory over the action against oxidative and free radicals: ketoprofen action

    International Nuclear Information System (INIS)

    Manente, Francine Alessandra; Mello, Lucas Rosolen de Almeida; Vellosa, Jose Carlos Rebuglio; Khalil, Omar Arafat Kdudsi; Carvalho, Claudio Teodoro de; Bannach, Gilbert

    2011-01-01

    Free radicals are highly reactive species generated in living organisms for the purpose of protection. However, in some circumstances, they are responsible for the occurrence or aggravation of tissue damage. Many anti-inflammatory drugs have a direct effect on free radicals and not radical reactive species, which contributes to its actions against inflammation. Ketoprofen is a nonsteroidal anti-inflammatory agent that generates free radicals by photo irradiation and has an important hemolytic effect with that. The complexation of metals to different drugs has been used as a strategy to improve the pharmacological action of different molecules and reduce their side effects. This paper presents the results of ketoprofen and their metallic complexes action on erythrocytes and free radicals. It was observed that the cerium enhances the scavenger properties of ketoprofen on free radicals, while copper enhances its action over non-radical oxidants. Copper also reduced the hemolytic effect presented by ketoprofen meanwhile its cerium derivative maintained it. (author)

  14. The research progress of several kinds of free radical scavengers

    International Nuclear Information System (INIS)

    Qian Liren; Huang Yuecheng; Cai Jianming

    2009-01-01

    Ionization radiation can generate free radicals in biological system, which could induce lipid peroxi-dation, biomacromolecule and biomembrane damage, lost of cell function, cell cycle disturbance, genetic mutation and so on. The scavenging free radicals can protect organism from radiation damage. Many radio-protective agents, such as amylase, hydroxyl-benzene derivatives, hormone, vitamin, have great abilities to protect organism from radiation via scavenging free radicals. In this paper, we mainly review the free radical scavenging effects of several kinds of radio-protective agents. (authors)

  15. Even free radicals should follow some rules: a guide to free radical research terminology and methodology.

    Science.gov (United States)

    Forman, Henry Jay; Augusto, Ohara; Brigelius-Flohe, Regina; Dennery, Phyllis A; Kalyanaraman, Balaraman; Ischiropoulos, Harry; Mann, Giovanni E; Radi, Rafael; Roberts, L Jackson; Vina, Jose; Davies, Kelvin J A

    2015-01-01

    Free radicals and oxidants are now implicated in physiological responses and in several diseases. Given the wide range of expertise of free radical researchers, application of the greater understanding of chemistry has not been uniformly applied to biological studies. We suggest that some widely used methodologies and terminologies hamper progress and need to be addressed. We make the case for abandonment and judicious use of several methods and terms and suggest practical and viable alternatives. These changes are suggested in four areas: use of fluorescent dyes to identify and quantify reactive species, methods for measurement of lipid peroxidation in complex biological systems, claims of antioxidants as radical scavengers, and use of the terms for reactive species. Copyright © 2014 Elsevier Inc. All rights reserved.

  16. The role of free radicals and antioxidants in reproduction.

    Science.gov (United States)

    Agarwal, Ashok; Gupta, Sajal; Sikka, Suresh

    2006-06-01

    This review summarizes the role of free radicals and oxidative stress in the pathophysiology of human reproduction. An extensive review of the literature on the role of oxidative stress in influencing assisted reproduction and its outcome is described in this article. Free radicals or reactive oxygen species mediate their action through many of the proinflammatory cytokines and this mechanism has been proposed as a common underlying factor for endometriosis, ovarian cancer, polycystic ovary disease, and various other pathologies affecting the female reproductive process, as highlighted in this review. Oxidative stress, sperm DNA damage, and apoptosis have been implicated in male infertility. Elevated reactive oxygen species levels correlate with the poor fertility outcomes seen in the assisted reproductive technology setting. Oxidative stress has been implicated in male and female infertility, including fetal dysmorphogenesis, abortions, and intrauterine growth restriction. Accurate evaluation of seminal oxidative stress by standardized assays may help in the diagnosis and management of male infertility. There is evidence in the literature on the beneficial effects of oral antioxidant supplementation in male infertility. Current ongoing trials will provide answers on the safety and effectiveness of antioxidants in improving maternal and fetal outcomes. Further studies need to be conducted to determine if antioxidant supplementation will prevent fetal developmental defects in high-risk pregnancy with diabetes.

  17. Oxidation and Free Radical Decay in Vitamin E-stabilized, Radiation Cross-linked UHMWPE

    International Nuclear Information System (INIS)

    Oral, E.

    2006-01-01

    A novel a-tocopherol (vitamin E, α-T)-stabilized, cross-linked ultra-high molecular weight polyethylene (UHMWPE) (αTPE) was developed for total joint arthroplasty as a bearing surface with low wear and improved mechanical properties. Accelerated aging showed α-T protects irradiated UHMWPE against oxidation. However, accelerated aging may not truly reflect in vivo and shelf oxidation. We used real-time aging to monitor the evolution of oxidation and free radical signals of α-T to determine the mechanism of oxidative stability. UHMWPE blocks (30x30x10 mm) were machined and γ-irradiated (85 kGy) in argon. The blocks were doped in α-T for 5 hours at 120 degree and homogenized for 64 hours at 120 degree in argon, packaged in vacuum and γ-sterilized (25 kGy). Samples were aged in air at room temperature, in air at 40 degree and in water at 40 degree. Measurements were at 1, 2, 3, 4 and 7 months. Sections cut from the aged blocks (150μm) were boiled in hexane overnight to extract free species and evaluated by FTIR. Oxidation indices were calculated by taking the area under the carbonyl peak and normalizing it to a skeletal peak. ESR was used to determine the content and type of free radicals. Control was 100-kGy irradiated, unstabilized UHMWPE. αTPE showed a small amount of oxidation, which stabilized after 2 months. This indicated that the decay of the hydroperoxides formed by the reaction of the residual free radicals with oxygen was exhausted by α-T due to its ability to scavenge free radicals. In contrast, control UHMWPE continued to oxidize because the residual free radicals likely continued to form hydroperoxides and additional free radicals, furthering the oxidation reactions. There was a shift in the free radical signature of both αTPE and control from the sextet alkyl/allyl radicals to a sharp singlet during aging. Most likely, trapped free radicals move along the crystal stems until they react with another free radical or until they reach the crystal

  18. Application of the EPR technique to examine free radical qualities reducing infection of spring wheat grain with pathogenic fungi by He-Ne laser irradiation

    International Nuclear Information System (INIS)

    Gagoś, M.; Koper, R.; Sujak, A.; Misiak, L.E.; Kowalczuk, E.

    2000-01-01

    Samples of spring wheat grain, Jasna cv., infected with pathogenic fungi (Aspergillus niger, Penicillium sp., Fusarium, Mucor) were examined using an EPR technique. Considering the quantity of generated free radicals the fungi belonged to most toxine generating. Their toxicity was connected with the number of free radicals generated in examined grain. Grain was irradiated with He-Ne laser at known wavelength, power density and time of exposure what gave the mycostatic effect appearing in decrease of free radicals in grain samples. However, this process was not stable as the increase of free radicals was observed again with the regrowth of fungi after some days

  19. Teaching Methods in Nutrition: Free Radicals, Antioxidants, and Human Disease.

    Science.gov (United States)

    Janowiak, John J.

    This article presents a teaching methodology for free radical theory and discusses the role of antioxidants in human health. Free radicals are a normal byproduct of respiration, which allows the body to use oxygen, liberate energy, and dispose of harmful substances. The body's antioxidants and nutritional antioxidants quench most of the free…

  20. Influence of Free Radicals on the Intrinsic MRI Relaxation Properties.

    Science.gov (United States)

    Tain, Rong-Wen; Scotti, Alessandro M; Li, Weiguo; Zhou, Xiaohong Joe; Cai, Kejia

    2017-01-01

    Free radicals are critical contributors in various conditions including normal aging, Alzheimer's disease, cancer, and diabetes. Currently there is no non-invasive approach to image tissue free radicals based on endogenous contrast due to their extremely short lifetimes and low in vivo concentrations. In this study we aim at characterizing the influence of free radicals on the MRI relaxation properties. Phantoms containing free radicals were created by treating egg white with various H 2 O 2 concentrations and scanned on a 9.4 T MRI scanner at room temperature. T 1 and T 2 relaxation maps were generated from data acquired with an inversion recovery sequence with varied inversion times and a multi-echo spin echo sequence with varied echo times (TEs), respectively. Results demonstrated that free radicals express a strong shortening effect on T 1 , which was proportional to the H 2 O 2 concentration, and a relatively small reduction in T 2 (free radicals was estimated to be in the pM range that is within the physiological range of in vivo free radical expression. In conclusion, the free radicals show a strong paramagnetic effect that may be utilized as an endogenous MRI contrast for its non-invasive in vivo imaging.

  1. 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.

  2. Free Radical Scavenging and Cellular Antioxidant Properties of Astaxanthin.

    Science.gov (United States)

    Dose, Janina; Matsugo, Seiichi; Yokokawa, Haruka; Koshida, Yutaro; Okazaki, Shigetoshi; Seidel, Ulrike; Eggersdorfer, Manfred; Rimbach, Gerald; Esatbeyoglu, Tuba

    2016-01-14

    Astaxanthin is a coloring agent which is used as a feed additive in aquaculture nutrition. Recently, potential health benefits of astaxanthin have been discussed which may be partly related to its free radical scavenging and antioxidant properties. Our electron spin resonance (ESR) and spin trapping data suggest that synthetic astaxanthin is a potent free radical scavenger in terms of diphenylpicryl-hydrazyl (DPPH) and galvinoxyl free radicals. Furthermore, astaxanthin dose-dependently quenched singlet oxygen as determined by photon counting. In addition to free radical scavenging and singlet oxygen quenching properties, astaxanthin induced the antioxidant enzyme paroxoanase-1, enhanced glutathione concentrations and prevented lipid peroxidation in cultured hepatocytes. Present results suggest that, beyond its coloring properties, synthetic astaxanthin exhibits free radical scavenging, singlet oxygen quenching, and antioxidant activities which could probably positively affect animal and human health.

  3. Insight into the Reaction Mechanism of Graphene Oxide with Oxidative Free Radical

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xuejiao; XU Liangyou

    2017-01-01

    Graphene oxide(GO),as an important derivative of graphene,could be considered as a super aromatic molecule decorated with a range of reactive oxygen-containing groups on its surface,which endows graphene high reactivity with other molecules.In our previous work,we demonstrated that GO sheets were cut into small pieces(graphene quantum dots,GQDs) by oxidative free radicals(hydroxyl radical HO or oxygen radical [O]) under UV irradiation.It is notable that reactions involving free radicals are influenced by reaction conditions pronouncedly.However,researches on details about reactions of GO with free radicals have not been reported thus far.In this work,the effects of different factors on the photo-Fenton reaction of GO were studied.It is demonstrated that the reaction rate is closely related to the concentration of free radicals.It is speculated that through the optimization of reaction conditions,the reaction of graphene with free radicals could carry out efficiently for further applications.

  4. Free radicals, oxygen and radiosensitizing drugs: a very brief introduction

    International Nuclear Information System (INIS)

    Willson, R.

    1981-01-01

    A review is presented of the historical aspects of the search for radiation sensitizing drugs. Metronidazole, Flagyl and misonidazole are undergoing clincial trials as the result of basic free radical and cellular research. Studies at the molecular, biochemical and cellular levels are described. From the information obtained it now appears that several processes may be involved in sensitization: interference with charge recombination due to a sensitizer having a high electron affinity; an increase in the yield of oxidizing hydroxyl radicals by electron sequestration; interference with radical combination reactions due to a sensitizer having a high one electron oxidation potential; oxidation or organic radicals so fixing them; formation of products which are toxic; and changes in the biochemistry of the cell. 106 references, 4 figures

  5. Study by electron spin resonance of the free radicals created under irradiation in glycine

    International Nuclear Information System (INIS)

    Thomet, P.; Rassat, A.; Servoz-Gavin, P.; Choudens, H. de

    1967-01-01

    The free radicals created by different radiations in glycine are measured by electron spin resonance and their number is evaluated in function of the absorbed dose. This number decreases when the LET of the radiations increases ; in other words,high LET radiations gives less radiochemical effects; in contrary with the fact that high LET radiations creates more damage in biological materials. The decreasing with time of the number of free radicals and the speed of this decrease is a function of temperature; by the study of the kinetics of this decrease, an attempt has been made to prove the presence of three radicals. (authors) [fr

  6. EPR studies of free radicals decay and survival in gamma irradiated aminoglycoside antibiotics: sisomicin, tobramycin and paromomycin.

    Science.gov (United States)

    Wilczyński, Sławomir; Pilawa, Barbara; Koprowski, Robert; Wróbel, Zygmunt; Ptaszkiewicz, Marta; Swakoń, Jan; Olko, Paweł

    2012-02-14

    Radiation sterilization technology is more actively used now that any time because of its many advantages. Gamma radiation has high penetrating power, relatively low chemical reactivity and causes small temperature rise. But on the other hand radiosterilization can lead to radiolytic products appearing, in example free radicals. Free radicals in radiative sterilized sisomicin, tobramycin and paromomycin were studied by electron paramagnetic resonance (EPR) spectroscopy. Dose of gamma irradiation of 25kGy was used. Concentrations and properties of free radicals in irradiated antibiotics were studied. EPR spectra were recorded for samples stored in air and argon. For gamma irradiated antibiotics strong EPR lines were recorded. One- and two-exponential functions were fitted to experimental points during testing and researching of time influence of the antibiotics storage to studied parameters of EPR lines. Our study of free radicals in radiosterilized antibiotics indicates the need for characterization of medicinal substances prior to sterilization process using EPR values. We propose the concentration of free radicals and other spectroscopic parameters as useful factors to select the optimal type of sterilization for the individual drug. The important parameters are i.a. the τ time constants and K constants of exponential functions. Time constants τ give us information about the speed of free radicals concentration decrease in radiated medicinal substances. The constant K(0) shows the free radicals concentration in irradiated medicament after long time of storage. Copyright © 2011 Elsevier B.V. All rights reserved.

  7. Xanthine oxidase activity and free radical generation in patients with sepsis syndrome

    DEFF Research Database (Denmark)

    Galley, H F; Davies, Michael Jonathan; Webster, N R

    1996-01-01

    OBJECTIVE: To determine xanthine oxidase activity, free radical concentrations, and lipid peroxidation in patients with sepsis syndrome compared with noninfected critically ill patients. DESIGN: A prospective observational study. SETTING: A nine-bed intensive care unit in a university teaching......). CONCLUSIONS: Patients with sepsis have xanthine oxidase activation, high free-radical concentrations, and evidence of free radical damage. The finding that xanthine oxidase activity was lower in those patients who died, coupled with increased lactate concentrations implies more severe ischemia with incomplete...... to the Acute Physiology and Chronic Health Evaluation (APACHE) II score or to the presence of organ dysfunction. The mean ascorbyl radical concentration (arbitrary units) determined by electron paramagnetic resonance following spin trapping was increased in patients compared with healthy subjects (p

  8. Experimental study of living free radical polymerization using trifunctional initiator and polymerization mediated by nitroxide

    International Nuclear Information System (INIS)

    Galhardo, Eduardo; Lona, Liliane M.F.

    2009-01-01

    Controlled free radical polymerization or living free radical polymerization has received increasing attention as a technique for the production of polymers with microstructure highly controlled. In particular, narrow molecular weight distributions are obtained with polydispersity very close to one. In this research it was investigate the controlled polymerization mediated by nitroxide, using a cyclic trifunctional peroxide. As long as we know, there are only publications in literature dealing with NMRP using mono- and bi-functional initiators. It was believed that the trifunctional peroxide can increase the rate of polymerization, since more free radicals are generated, if compared with initiators with lower functionality. Furthermore, the fact of the initiator be cyclic means that branches are not generated in the chains, which theoretically prevents an increase in polydispersity of the polymer. The effect of the dissociation constant of the trifunctional initiator in the velocity of the reaction was analyzed. (author)

  9. In vitro free radical scavenging activity of Ixora coccinea L

    Directory of Open Access Journals (Sweden)

    Moni Rani Saha

    2008-06-01

    Full Text Available Antioxidant activity of the methanol extract of Ixora coccinea L. was determined by DPPH free radical scavenging assay, reducing power and total antioxidant capacity using phosphomolybdenum method. Preliminary phytochemical screening revealed that the extract of the flower of I. coccinea possesses flavonoids, steroids and tannin materials. The extract showed significant activities in all antioxidant assays compared to the standard antioxidant in a dose dependent manner and remarkable activities to scavenge reactive oxygen species (ROS may be attributed to the high amount of hydrophilic phenolics. In DPPH radical scavenging assay the IC50 value of the extract was found to be 100.53 μg/mL while ascorbic acid had the IC50 value 58.92 μg/mL. Moreover, I. coccinea extract showed strong reducing power and total antioxidant capacity.

  10. [Research progress on free radicals in human body].

    Science.gov (United States)

    Wang, Q B; Xu, F P; Wei, C X; Peng, J; Dong, X D

    2016-08-10

    Free radicals are the intermediates of metabolism, widely exist in the human bodies. Under normal circumstances, the free radicals play an important role in the metabolic process on human body, cell signal pathway, gene regulation, induction of cell proliferation and apoptosis, so as to maintain the normal growth and development of human body and to inhibit the growth of bacteria, virus and cancer. However, when organic lesion occurs affected by external factors or when equilibrium of the free radicals is tipped in the human body, the free radicals will respond integratedly with lipids, protein or nucleic acid which may jeopardize the health of human bodies. This paper summarizes the research progress of the free radicals conducted in recent years, in relations to the perspective of the types, origins, test methods of the free radicals and their relationship with human's health. In addition, the possible mechanisms of environmental pollutants (such as polycyclic aromatic hydrocarbons) mediating oxidative stress and free radicals scavenging in the body were also summarized.

  11. Transmission of Free Radicals through and Damage to Freestanding Single and Multilayer Dielectric Film

    Science.gov (United States)

    Choudhury, Faraz Anwar

    A high concentration of free radicals is present in many processing plasmas, which affects the processing conditions and the properties of materials exposed to the plasma. Measuring the types and concentrations of free radicals present in the plasma is critical in order to determine their effects on the materials being processed. Current methods for detecting free radicals in a plasma require multiple expensive and bulky instruments, complex setups and often modifications to the plasma reactor. In this work, we present a simple technique that detects reactive-oxygen radicals incident on a surface from a plasma. The measurements are made using a fluorophore dye that is commonly used in biological and cellular systems for assay labeling in liquids. Using fluorometric analysis, it was found that the fluorophore reacts with oxygen radicals incident from the plasma, which is indicated by degradation of its fluorescence. As plasma power was increased, the quenching of the fluorescence significantly increased. Both immobilized and non-immobilized fluorophore dyes were used and the results indicate that both states function effectively under vacuum conditions. Using radical-sensitive dyes and free-standing films, the transmission of oxygen radicals through silicon nitride and silicon dioxide dielectric films is measured and their absorption lengths are determined. The absorption lengths were found to be 33, 37 and 40 nm for 15, 30 and 45-minute oxygen plasma exposures respectively. FTIR and XRR measurements show that a silicon oxynitride-like layer forms on the surface of the film which has a lower density than silicon nitride. The increase in absorption length with plasma-exposure time is attributed to the formation of the surface layer. In silicon dioxide films, the absorption length of oxygen radicals was found to be 70 nm after 20 minutes of plasma exposure. After 30 minutes of plasma exposure under the same conditions, the absorption length was reduced to 66 nm. XRR

  12. Flavonoids: hemisynthesis, reactivity, characterization and free radical scavenging activity.

    Science.gov (United States)

    Es-Safi, Nour-Eddine; Ghidouche, Souhila; Ducrot, Paul Henri

    2007-09-26

    Phenolic compounds form one of the main classes of secondary metabolites. They display a large range of structures and they are responsible for the major organoleptic characteristics of plant-derived-foods and beverages, particularly color and taste properties and they also contribute to the nutritional qualities of fruits and vegetables. Phenolic compounds are also highly unstable compounds which undergo numerous enzymatic and chemical reactions during postharvest food storage and processing thus adding to the complexity of plant polyphenol composition. Among these compounds flavonoids constitute one of the most ubiquitous groups of all plant phenolics. Owing to their importance in food organoleptic properties and in human health, a better understanding of their structures, their reactivity and chemical properties in addition to the mechanisms generating them appears essential to predict and control food quality. The purpose of this work is an overview of our findings concerning the hemisynthesis, the reactivity and the enzymatic oxidation of some flavonoids and shed light on the mechanisms involved in some of these processes and the structures of the resulting products. The free radical scavenging activity of some of the synthesized compounds is also presented and a structure-activity relationship is discussed. The first part of this review concerns the synthesis and structural characterization of modified monomeric flavanols. The use of these compounds as precursor for the preparation of natural and modified dimeric procyanidin derivatives was then explored through different coupling reactions. The full characterization of the synthesized compounds was achieved by concerted use of NMR and ESI-MS techniques. The free radical scavenging activity of some of the synthesized compounds was investigated. The second part of this review concerns the enzymatic oxidation of several flavonols by Trametes versicolor laccase. Most of the major oxidation products have been

  13. Flavonoids: Hemisynthesis, Reactivity, Characterization and Free Radical Scavenging Activity

    Directory of Open Access Journals (Sweden)

    Paul Henri Ducrot

    2007-09-01

    Full Text Available Phenolic compounds form one of the main classes of secondary metabolites. They display a large range of structures and they are responsible for the major organoleptic characteristics of plant-derived-foods and beverages, particularly color and taste properties and they also contribute to the nutritional qualities of fruits and vegetables. Phenolic compounds are also highly unstable compounds which undergo numerous enzymatic and chemical reactions during postharvest food storage and processing thus adding to the complexity of plant polyphenol composition. Among these compounds flavonoids constitute one of the most ubiquitous groups of all plant phenolics. Owing to their importance in food organoleptic properties and in human health, a better understanding of their structures, their reactivity and chemical properties in addition to the mechanisms generating them appears essential to predict and control food quality. The purpose of this work is an overview of our findings concerning the hemisynthesis, the reactivity and the enzymatic oxidation of some flavonoids and shed light on the mechanisms involved in some of these processes and the structures of the resulting products. The free radical scavenging activity of some of the synthesized compounds is also presented and a structure-activity relationship is discussed. The first part of this review concerns the synthesis and structural characterization of modified monomeric flavanols. The use of these compounds as precursor for the preparation of natural and modified dimeric procyanidin derivatives was then explored through different coupling reactions. The full characterization of the synthesized compounds was achieved by concerted use of NMR and ESI-MS techniques. The free radical scavenging activity of some of the synthesized compounds was investigated. The second part of this review concerns the enzymatic oxidation of several flavonols by Trametes versicolor laccase. Most of the major oxidation

  14. Free Radical Scavenging Properties of Annona squamosa

    Science.gov (United States)

    Vikas, Biba; Akhil B, S; P, Remani; Sujathan, K

    2017-10-26

    Annona squamosa has extensively been used in the traditional and folkloric medicine and found to possess many biological activities. Different solvents, petroleum ether, chloroform, ethyl acetate and methanol extracts of Annona squamosa seeds (ASPE, ASCH, ASEA, ASME) have been used to prepare plant extracts. The present investigations dealt with the free radical scavenging activity of four extracts using various techniques such as total reducing power estimation, total phenolic count, 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging effect, evaluation of ABTS cation decolorisation capacity, FRAP assay, hdroxyl radical scavenging assay, super oxide assay and Nitric oxide radical scavenging assay of the extracts. The results showed that the four extracts of Annona squamosa showed significant reducing power in four extracts. The total phenolic contents in petroleum ether, chloroform, ethyl acetate, methanol extracts and positive control were 0.64±0.17, 0.54±0.27, 0.49±0.24, 0.57±0.22 and 0.66±0.33. The antioxidant capacity by ABTS assay of ASPE, ASCH, ASEA, ASME and positive control, trolox showed 77.75±0.5,73.25±1.7,78.5± 1.2 , 80 ± 0.8 μg/ml and 94.2 ± 0.9 respectively. The (50 % scavenging activity) SA50 of ASPE and ASCH, ASEA and ASME was found to be 34.4 μg/ml, 43.8 μg/ml 34.7 μg/m and 28.8 μg/ml respectively by DPPH assay. The percentage of hydroxyl radical scavenging increased with the increasing concentration of the extracts. ASPE, ASCH, ASEA and ASME showed superoxide radical scavenging activity, as indicated by their values 66 ± 0.5, 68 ± 1 ,63 ± 1 and 70 ± 0.5 μg/ml respectively compared to gallic acid which was 97 ± 0.5 μg/ml. The values for scavenging of nitric oxide for ASPE, ASCH, ASEA and ASME were 91.0 ± 1.0, 66.75 ± 0.5, 71.75 ± 1.1 and 75.75 ± 1.15 μg/ml while value for standard ascorbic acid was 91.0 ± 1.0 μg/ml. The results revealed strong antioxidants in four extracts may lead to the development of potent

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

    Science.gov (United States)

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

    2013-03-13

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

  16. Comparative study of copper(II)-curcumin complexes as superoxide dismutase mimics and free radical scavengers.

    Science.gov (United States)

    Barik, Atanu; Mishra, Beena; Kunwar, Amit; Kadam, Ramakant M; Shen, Liang; Dutta, Sabari; Padhye, Subhash; Satpati, Ashis K; Zhang, Hong-Yu; Indira Priyadarsini, K

    2007-04-01

    Two stoichiometrically different copper(II) complexes of curcumin (stoichiometry, 1:1 and 1:2 for copper:curcumin), were examined for their superoxide dismutase (SOD) activity, free radical-scavenging ability and antioxidant potential. Both the complexes are soluble in lipids and DMSO. The formation constants of the complexes were determined by voltammetry. EPR spectra of the complexes in DMSO at 77K showed that the 1:2 Cu(II)-curcumin complex is square planar and the 1:1 Cu(II)-curcumin complex is distorted orthorhombic. Cu(II)-curcumin complex (1:1) with larger distortion from square planar structure shows higher SOD activity. These complexes inhibit gamma-radiation induced lipid peroxidation in liposomes and react with DPPH acting as free radical scavengers. One-electron oxidation of the two complexes by radiolytically generated azide radicals in Tx-100 micellar solutions produced phenoxyl radicals, indicating that the phenolic moiety of curcumin in the complexes participates in free radical reactions. Depending on the structure, these two complexes possess different SOD activities, free radical neutralizing abilities and antioxidant potentials. In addition, quantum chemical calculations with density functional theory have been performed to support the experimental observations.

  17. EFFECT OF CADMIUM(II) ON FREE RADICALS IN DOPA-MELANIN TESTED BY EPR SPECTROSCOPY.

    Science.gov (United States)

    Zdybel, Magdalena; Pilawa, Barbara; Chodurek, Ewa

    2015-01-01

    Electron paramagnetic resonance (EPR) spectroscopy may be applied to examine interactions of melanin with metal ions and drugs. In this work EPR method was used to examination of changes in free radical system of DOPA-melanin--the model eumelanin after complexing with diamagnetic cadmium(II) ions. Cadmium(II) may affect free radicals in melanin and drugs binding by this polymer, so the knowledge of modification of properties and free radical concentration in melanin is important to pharmacy. The effect of cadmium(II) in different concentrations on free radicals in DOPA-melanin was determined. EPR spectra of DOPA-melanin, and DOPA-melanin complexes with cadmium(II) were measured by an X-band (9.3 GHz) EPR spectrometer produced by Radiopan (Poznań, Poland) and the Rapid Scan Unit from Jagmar (Krak6w, Poland). The DOPA (3,4-dihydroxyphenylalanine) to metal ions molar ratios in the reaction mixtures were 2:1, 1:1, and 1: 2. High concentrations of o-semiquinone (g ~2.0040) free radicals (~10(21)-10(22) spin/g) characterize DOPA-melanin and its complexes with cadmium(II). Formation of melanin complexes with cadmium(II) increase free radical concentration in DOPA-melanin. The highest free radical concentration was obtained for DOPA-melanin-cadmium(II) (1:1) complexes. Broad EPR lines with linewidths: 0.37-0.73 mT, were measured. Linewidths increase after binding of cadmium(II) to melanin. Changes of integral intensities and linewidths with increasing microwave power indicate the homogeneous broadening of EPR lines, independently on the metal ion concentration. Slow spin-lattice relaxation processes existed in all the tested samples, their EPR lines saturated at low microwave powers. Cadmium(II) causes fastening of spin-lattice relaxation processes in DOPA-melanin. The EPR results bring to light the effect of cadmium(II) on free radicals in melanin, and probably as the consequence on drug binding to eumelanin.

  18. Tissue diversity in respiratory metabolism and free radical processes ...

    African Journals Online (AJOL)

    SAM

    2014-04-23

    Apr 23, 2014 ... marina seeds to desiccation contributes to an under- standing of the ... normal, thus increasing the generation of free radical ...... A review of recalcitrant seed physio- ... In: Kigel J, Galili G (eds) Seed development and germina-.

  19. Free Radicals and Antioxidants in Cardiovascular Health and Disease

    African Journals Online (AJOL)

    Free radicals can be overproduced or the natural antioxidant system defenses weakened, first resulting in oxidative stress, and then leading to oxidative injury ... Keywords: Oxidative stress, cardiovascular disease, atherosclerosis, inflammation, cell signaling and transduction mechanisms, antioxidants, dietary phenolics.

  20. Antimicrobial and free radical scavenging activities of five ...

    African Journals Online (AJOL)

    Extracts from five indigenous Palestinian medicinal plants including Rosmarinus officinalis, Pisidium guajava, Punica granatum peel, grape seeds and Teucrium polium were investigated for antimicrobial and free radical scavenging activities against eight microorganisms, using well diffusion method. The microorganisms ...

  1. Study progress on free radicals and graves disease

    International Nuclear Information System (INIS)

    Zhang Ruiguo; Jin Jianhua

    2009-01-01

    Free radical-mediated oxidative injury has been closely implicated in the occurrence and development of many diseases. Graves disease was also accompanied by changes of the free radicals, especially for reactive oxygen species and reactive nitrogen, et al, and the oxidative stress can cause a certain degree of injury on the thyroid and other human important organs. Antithyroid drug and 131 I treatment of Graves disease, the oxidative and antioxidative parameters can also be changed. (authors)

  2. Free radical interactions between raw materials in dry soup powder.

    Science.gov (United States)

    Raitio, Riikka; Orlien, Vibeke; Skibsted, Leif H

    2011-12-01

    Interactions at the free radical level were observed between dry ingredients in cauliflower soup powder, prepared by dry mixing of ingredients and rapeseed oil, which may be of importance for quality deterioration of such dry food products. The free radical concentrations of cauliflower soup powder, obtained by electron spin resonance (ESR) spectroscopy, rapidly become smaller during storage (40°C and relative humidity of 75%) than the calculated concentrations of free radicals based on the free radical concentrations of the powder ingredients used to make the soup powder and stored separately under similar conditions. Similarly, free radical concentrations decreased faster when any combination of two powder ingredients (of the three major ingredients of the soup powder) were mixed together and stored at 50°C for 1week than when each powder component was stored separately. Furthermore, yeast extract powder was found to play a key role when free radical interactions between powder ingredients occurred. The incubation of rapeseed oil with powder ingredients at 45°C for 24h, indicated the ability of cauliflower powder to increase the concentration of hydroperoxides in rapeseed oil, while yeast extract powder was found to prevent this hydroperoxide formation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Application of stable, nitroxide free radicals in solution to low magnetic fields measurements

    International Nuclear Information System (INIS)

    Besson, Rene

    1973-01-01

    The first attempts to use the Overhauser-Abragam effect for measuring low magnetic fields date back to 1956. However, the instability of the free radical used, PREMY'S Salt, as well as its virtual insolubility in solvents other than water, hampered the development of the nuclear magnetic resonance magnetometer realized in accordance to this principle: dynamic polarization of protons. New free radicals stable and soluble in many solvents, will enhanced the interest in the device. In particular, the use of 2,2,6,6, tetramethyl- piperidine-4-one-1-oxide (TANO or TANONE) leads to a high sensitivity, low field magnetometer. The methods of measurements, the required apparatus and sample preparation are first described. Next the results of measurements made both in high and low magnetic fields with various free radicals in different solvents are presented in tabular and graphical form. These measurements have determined which radical-solvent couple will yield a high dynamic polarization coefficient. In addition, the improvement obtained by complete deuteration of the free radical has been demonstrated. Problems connected with the application of such radicals in solution to the 'double effect probe' of the magnetometer built by LETI at CEN Grenoble and the solutions reached are discussed. (author) [fr

  4. The role of melanin as protector against free radicals in skin and its role as free radical indicator in hair

    Science.gov (United States)

    Herrling, Thomas; Jung, Katinka; Fuchs, Jürgen

    2008-05-01

    Throughout the body, melanin is a homogenous biological polymer containing a population of intrinsic, semiquinone-like radicals. Additional extrinsic free radicals are reversibly photo-generated by UV and visible light. Melanin photochemistry, particularly the formation and decay of extrinsic radicals, has been the subject of numerous electron spin resonance (ESR) spectroscopy studies. Several melanin monomers exist, and the predominant monomer in a melanin polymer depends on its location within an organism. In skin and hair, melanin differs in content of eumelanin or pheomelanin. Its bioradical character and its susceptibility to UV irradiation makes melanin an excellent indicator for UV-related processes in both skin and hair. The existence of melanin in skin is strongly correlated with the prevention against free radicals/ROS generated by UV radiation. Especially in the skin melanin (mainly eumelanin) ensures the only natural UV protection by eliminating the generated free radicals/ROS. Melanin in hair can be used as a free radical detector for evaluating the efficacy of hair care products. The aim of this study was to investigate the suitability of melanin as protector of skin against UV generated free radicals and as free radical indicator in hair.

  5. The entry of free radicals into polystyrene latex particles

    International Nuclear Information System (INIS)

    Adams, M.E.; Trau, M.; Gilbert, R.C.; Napper, D.R.

    1988-01-01

    Mechanistic understanding of the processes governing the kinetics of emulsion polymerization has both scientific and technical interest. One component of this process that is poorly understood at present is that of free radical entry into latex particles. Measurements were made of the entry rate coefficient as a function of temperature for free radicals entering polystyrene latex particles in seeded emulsion polymerizations initiated by γ-rays. The activation energy for entry was found to be less than 24 ± 3 kJ mol -1 , consistent with entry being controlled by a physical (e.g. diffusional) rather than a chemical process. Measurement of the entry rate coefficient as a function of the γ-ray dose rate suggested that the factors that determine the entry rate when the primary free radicals are uncharged are similar to those that determine the entry rate for charged free radicals derived from chemical initiation by peroxydisulfate. This result was consistent with measurements of the entry rate coefficient of charged free radicals derived from peroxydisulfate; these data were found to be virtually independent of both the extent of the latex surface coverage by the anionic surfactant sodium dodecyl sulfate and the ionic strength of the continuous phase. The data refute several proposals given in the literature for the rate-determining step for entry, being inconsistent with control by collision of free radicals with the latex particles, surfactant desorption, and an electrostatic barrier arising from the colloidal nature of the entering free radical. The origin of the activation energy for entry remains obscure

  6. Free radical activity during development of insulin-dependent diabetes mellitus in the rat

    Energy Technology Data Exchange (ETDEWEB)

    Pitkaenen, O.M.; Akerblom, H.K.; Sariola, H.; Andersson, S.M. (Univ. of Helsinki (Finland)); Martin, J.M. (Hospital for Sick Children, Toronto, Ontario (Canada)); Hallman, M. (Univ. of California, Irvine (United States))

    1991-01-01

    Free radical-induced lipid peroxidation was quantified by measuring expired pentane from diabetic prone BB Wistar rats of 45-90 d of age. Insulin-dependent diabetes mellitus was manifest at the age of 71 {plus minus} 8 d. Expired pentane increased from 2.1 {plus minus} 0.7 to 5.0 {plus minus}3.0 pmol/100g/min (p <0.01) at manifestation of the disease and remained high throughout the test period. In healthy age-matched control rats it persisted low. In rats made diabetic with streptozotocin, expired pentane remained low. The changes in expired pentane suggest that the development of endogenous insulin-dependent diabetes mellitus in BB rats is associated with increased free radical activity. This is not due to hyperglycemia or ketosis per se, and reflects a fundamental difference in the free radical activity between the spontaneously diabetic BB rats and the disease produced by streptozotocin. Development of spontaneous insulin-dependent diabetes in BB rats is associated with increased free radical activity that persists after the manifestation of the disease.

  7. [The significance of free radicals and antioxidants due to the load induced by sport activity].

    Science.gov (United States)

    Holecek, V; Liska, J; Racek, J; Rokyta, R

    2004-01-01

    Sport performance is followed by a high production of free radicals. The main reasons are reperfusion after the previous imbalance between the increased need of the organism and the ability of blood supply by oxygen, increased production of ATP, decomposition of the cells particularly white blood cells, oxidation of the purin basis from DNA, stress, output of epinephrine release of free iron, increased temperature in the muscle and its inflammation, and the reception of free radicals from external environment. Peroxidation of lipids, proteins, DNA and other compounds follows the previous biochemical steps. Antioxidants are consumed by free radicals, antioxidative enzymes are released into blood plasma, intracellular calcium is increased, the production of nitric oxide rises, the levels of hydrogen peroxide and hypochlorous acid increase. These penetrate through the membranes and oxidatively damage the tissues. Training improves the ability of the organism to balance the increased load of free radicals. The damage can be lowered by the application of a mixture of antioxidants, the most important are vitamin C, A, E, glutathione, selenium, carnosine, eventually bioflavonoids and ginkgo biloba. The lack of antioxidants can significantly diminish the sport performance and therefore the supplementation with antioxidants is for top sportsmen but also for aged people advisable.

  8. Synoviocytes, not chondrocytes, release free radicals after cycles of anoxia/re-oxygenation

    International Nuclear Information System (INIS)

    Schneider, Nicole; Mouithys-Mickalad, Ange L.; Lejeune, Jean-Philippe; Deby-Dupont, Ginette P.; Hoebeke, Maryse; Serteyn, Didier A.

    2005-01-01

    By oxymetry and electron paramagnetic resonance (EPR), we investigated the effects of repeated anoxia/re-oxygenation (A/R) periods on the respiration and production of free radicals by synoviocytes (rabbit HIG-82 cell line and primary equine synoviocytes) and equine articular chondrocytes. Three periods of 20 min anoxia followed by re-oxygenation were applied to 10 7 cells; O 2 consumption was measured before anoxia and after each re-oxygenation. After the last A/R, cellular free radical formation was investigated by EPR spectroscopy with spin trapping technique (n = 3 for each cell line). Both types of synoviocytes showed a high O 2 consumption, which was slowered after anoxia. By EPR with the spin trap POBN, we proved a free radical formation. Results were similar for equine and rabbit synoviocytes. For chondrocytes, we observed a low O 2 consumption, unchanged by anoxia, and no free radical production. These observations suggest an oxidant activity of synoviocytes, potentially important for the onset of osteoarthritis

  9. Study of new compounds for their application on free radicals EPR dosimetry

    International Nuclear Information System (INIS)

    Condes N, C.S.

    1996-01-01

    L- α alanine is an amino acid which has been used for electron and γ ray dosimetric purposes, when crystallites of L-α alanine are irradiated with ionizing radiation free radicals are produced. The yield of free radicals produced by irradiation of alanine crystals can be evaluated by EPR spectrometry, however when L- α alanine crystals are irradiated with thermal neutrons the yield of the free radicals produced is very low and in consequence it's EPR-signal response is poor. In this work we mixed L-α alanine together with some lithium compounds such as LiF, LiBO 2 , LiOH and Li 2 CO 3 . In this way when we irradiate the respective mixture of alanine-lithium with thermal neutrons, the nuclear reactions 6 Li (n,α)T and 10 B (n, α) 7 Li can be produced with a high probability. As a consequence α particles and recoil atoms emerging from the nuclear reactions can impinge on alanine molecules, producing extra free radicals. From the alanine-lithium mixtures obtained, we made dosemeters (30 mm long., 3.9 mm diameter) which were irradiated in the thermal column of the TRIGA Mark III Nuclear Reactor with a flux of thermal neutrons of 5 x 10 7 n/ cm 2 s. Irradiations were made at different periods. Experimental evaluations indicate that the mixtures can be used for dosimetric purposes. (Author)

  10. Propofol Effect on Stress Response and Free Radicals in Patient during Surgery and Sedation Procedure

    Directory of Open Access Journals (Sweden)

    Theresia Monica Rahardjo

    2015-12-01

    Full Text Available BACKGROUND: Propofol is an intravenous anesthetic used worldwide as an anesthesia induction and maintenance agent. Propofol also used as sedation agent in Intensive Care Unit (ICU. Despite it’s usual anesthesia properties, propofol has an unique pharmacologic characteristic, especially as antioxidant and stress response reduction. These advantages suggested propofol has positive effects when used as an anesthesia agent in surgery or sedation in ICU in conditions when high stress and free radical level are released. CONTENT: Stress response and free radical can be elevated in various conditions including surgery or during care in ICU, especially critical ill patient. Cortisol is a major stress hormone that influences metabolism, cardiovascular and central nervous system, either in acute or chronic phase. Oxidative stress was marked by free radical elevation called Radical Oxygen Species (ROS. Combination of both elements (cortisol and ROS can worsen patient condition. Propofol with anti-stress and antioxidant properties could be used to reduce stress response and attenuate free radical level in order to improve patient condition. SUMMARY: The anti-stress and antioxidant properties of Propofol are interesting, because these benefits can be added as adjunctive therapy when propofol was used as an anesthetic agent in surgery and a sedation in ICU. KEYWORDS: propofol, stress response, antioxidant.

  11. Free radicals and lipid peroxidation mediated injury in burn trauma: the role of antioxidant therapy

    International Nuclear Information System (INIS)

    Horton, Jureta W.

    2003-01-01

    Burn trauma produces significant fluid shifts that, in turn, reduce cardiac output and tissue perfusion. Treatment approaches to major burn injury include administration of crystalloid solutions to correct hypovolemia and to restore peripheral perfusion. While this aggressive postburn volume replacement increases oxygen delivery to previously ischemic tissue, this restoration of oxygen delivery is thought to initiate a series of deleterious events that exacerbate ischemia-related tissue injury. While persistent hypoperfusion after burn trauma would produce cell death, volume resuscitation may exacerbate the tissue injury that occurred during low flow state. It is clear that after burn trauma, tissue adenosine triphosphate (ATP) levels gradually fall, and increased adenosine monophosphate (AMP) is converted to hypoxanthine, providing substrate for xanthine oxidase. These complicated reactions produce hydrogen peroxide and superoxide, clearly recognized deleterious free radicals. In addition to xanthine oxidase related free radical generation in burn trauma, adherent-activated neutrophils produce additional free radicals. Enhanced free radical production is paralleled by impaired antioxidant mechanisms; as indicated by burn-related decreases in superoxide dismutase, catalase, glutathione, alpha tocopherol, and ascorbic acid levels. Burn related upregulation of inducible nitric oxide synthase (iNOS) may produce peripheral vasodilatation, upregulate the transcription factor nuclear factor kappa B (NF-κB), and promote transcription and translation of numerous inflammatory cytokines. NO may also interact with the superoxide radical to yield peroxynitrite, a highly reactive mediator of tissue injury. Free radical mediated cell injury has been supported by postburn increases in systemic and tissue levels of lipid peroxidation products such as conjugated dienes, thiobarbituric acid reaction products, or malondialdehyde (MDA) levels. Antioxidant therapy in burn therapy

  12. Free radicals created by radiation and aging symptoms

    International Nuclear Information System (INIS)

    Ashry, O.M.

    2012-01-01

    The universality of aging implies that its cause is basically the same in all species. A free radical hypothesis of aging has been proposed that the free radicals produced during normal metabolism of the cell over time damage DNA and other macromolecules leading to degenerative diseases, malignancies, and eventual death of vital cells which in turn causes aging and death of the organism. This hypothesis is supported by several observations. Radiation produces its biologic effect through free radical formation and causes premature aging. Second, the age pigment lipo fuscin is associated with lipid peroxidation. The hypothesis that oxygen radicals play a role in aging is also supported by the observation that, in general, long-lived species produce less endogenous free oxygen radicals because of their lower metabolic rate. Long-lived animals also have more superoxide dismutase than do their short-lived counterparts, and animal species with the longest lifespan have the highest levels of superoxide dismutase. Oxidative DNA damage is rapidly and effectively repaired. It has been estimated that there are several thousand oxidative DNA damage sites in a human cell every day, and the majority of these are repaired. However, a small fraction of unrepaired lesions could cause permanent changes in DNA and might be a major contributor to aging and cancer. A consequence of the free radical hypothesis of aging is the idea that free radical scavenging agents might be used to prevent aging. (author)

  13. Photoactivation of isoflavonoid phytoalexins: involvement of free radicals

    International Nuclear Information System (INIS)

    Bakker, J.; Gommers, F.J.; Smits, L.; Fuchs, A.; Vries, F.W. de

    1983-01-01

    Ultraviolet irradiation of isoflavonoid phytoalexins phaseollin, 3.6a. 9-trihydroxypterocarpan, glyceollin, tuberosin and pisatin, but not medicarpin, brought about inactivation of glucose-6-phosphate dehydrogenase in an in vitro assay system. Photoinactivation of the enzyme by photoactivated pisatin in air-saturated solutions was hardly affected by singlet oxygen quenchers such as NaN 3 , bovine serum albumin, histidine or methionine. Neither addition of the hydroxyl radical scavengers mannitol, Na-benzoate and ethanol nor the presence of catalase or superoxide dismutase protected the enzyme against photoinactivation, suggesting that OHradical, H 2 O 2 and O 2 radical are not the reactive oxygen species involved. However, the free radical scavenger S-(2-amino-ethyl)isothiouronium bromide hydrobromide (AET) protected the enzyme against inactivation by photoactivated pisatin. Direct evidence for the generation of free radicals was obtained by ESR measurements of solutions of phaseollin, pisatin and medicarpin in hexane irradiated with ultraviolet light in the presence or absence of O 2 . Phaseollin produced the most stable free radicals, whereas medicarpin hardly gave rise to free radical formation; pisatin took a somewhat intermediate position by producing a strong ESR signal which, however, decayed rather quickly. These results indicate free radical formation as the cause for photoinactivation of enzymes by photoactivated isoflavonoid phytoalexins. (author)

  14. Effect of Free Radicals & Antioxidants on Oxidative Stress: A Review

    Directory of Open Access Journals (Sweden)

    Ashok Shinde

    2012-01-01

    Full Text Available Recently free radicals have attracted tremendous importance in the field of medicine including dentistry and molecular biology. Free radicals can be either harmful or helpful to the body. When there is an imbalance between formation and removal of free radicals then a condition called as oxidative stress is developed in body. To counteract these free radicals body has protective antioxidant mechanisms which have abilities to lower incidence of various human morbidities and mortalities. Many research groups in the past have tried to study and confirm oxidative stress. Many authors also have studied role of antioxidants in reducing oxidative stress. They have come across with controversial results and furthermore it is not yet fully confirmed whether oxidative stress increases the need for dietary antioxidants. Recently, an association between periodontitis and cardiovascular disease has received considerable attention. Various forms of antioxidants have been introduced as an approach to fight dental diseases and improve general gingival health. The implication of oxidative stress in the etiology of many chronic and degenerative diseases suggests that antioxidant therapy represents a promising avenue for treatment. This study was conducted with the objective of reviewing articles relating to this subject. A Pub Med search of all articles containing key words free radicals, oxidative stress, and antioxidants was done. A review of these articles was undertaken.

  15. The Nanoconfined Free Radical Polymerization: Reaction Kinetics and Thermodynamics

    Science.gov (United States)

    Zhao, Haoyu; Simon, Sindee

    The reaction kinetics and thermodynamics of nanoconfined free radical polymerizations are investigated for methyl methacrylate (MMA) and ethyl methacrylate (EMA) monomers using differential scanning calorimetry. Controlled pore glass is used as the confinement medium with pore diameters as small as 7.5 nm; the influence of both hydrophobic (silanized such that trimethylsilyl groups cover the surface) and hydrophilic (native silanol) surfaces is investigated. Propagation rates increase when monomers are reacted in the hydrophilic pores presumably due to the specific interactions between the carbonyl and silanol groups; however, the more flexible EMA monomer shows weaker effects. On the other hand, initial rates of polymerization in hydrophobic pores are unchanged from the bulk. In both pores, the onset of autoacceleration occurs earlier due to the reduced diffusivity of confined chains, which may be compensated at high temperatures. In addition to changes in kinetics, the reaction thermodynamics can be affected under nanoconfinement. Specifically, the ceiling temperature (Tc) is shifted to lower temperatures in nanopores, with pore surface chemistry showing no significant effects; the equilibrium conversion is also reduced at high temperatures below Tc. These observations are attributed to a larger negative change in entropy on propagation for the confined system, with the MMA system again showing greater effects. Funding from ACS PRF is gratefully acknowledged.

  16. Free radical scavenging properties of some wine probes

    International Nuclear Information System (INIS)

    Stasko, A.; Liptakova, M.; Malik, F.

    1999-01-01

    There are preliminary results of investigation of scavenging properties of 8 probes of Slovak wines (consisting of one reference, 3 probes of white wine and 4 probes of red wine). According to the literature so far, wine probes contain paramagnetic species (Mn 2+ , characterised with sextet spectrum, and a singlet line around g=2,00). In our probes we observed Mn 2+ signals, but no significant evidence for a single line of free radical was found. We can conclude that Mn 2+ content in the red wines is generally higher than in the white ones. Further, we investigated the scavenging activities of the probes adding solution of dinitropicryl hydrazyl (DPPH-stable radical) to them. Their ability to terminate free radicals resulted in the decrease of the final DPPH concentrations in the probes. The red wines have significantly higher capability to scavenge free radicals than the probes of white wines. (authors)

  17. Deciphering free-radical code of radiation effects

    International Nuclear Information System (INIS)

    Volovyk, S.; Bazyka, D.; Loganovsky, K.; Bebeshko, V.

    2007-01-01

    Complete text of publication follows. Objective: Ionizing radiation is fundamental environmental factor for life origin and evolution. Free radicals, primordial 'sea' for life conceiving and existence, induced by cosmic and terrestrial background radiation, are evolutionally archetypal, ubiquitous, and omnipotent in physiological- pathophysiological dichotomy. Classical free-radical paradigm in radiation biology and medicine, focused in essence on oxidative damage, needs new conceptualization and generalization. Methods: Suggested novel insights into free radicals dual immanent nature and functions in organism systems are based on original concepts of radicals dynamic charge transfer (CT) - redox ambivalence (interactional nucleo-, electro-, and ambiphilicity spectrum); pertinent chemical reactivity and selectivity delocalization model; physiological functional ambivalence and complementarity, and dynamic free-radical homeostasis. Results: Subtle perturbations in radicals CT spatiotemporal homeodynamics, in responsive signaling / controlling networks, concomitant alterations in genes expression, transcription, and apoptosis, redox control of mitochondrial ET chain, telomere/telomerase balance, DNA CT, circadian clock, hemispheric biochemical dominance/accentuation, including alteration of nitric oxide-superoxide complementarity, membranes permeability, neurotransmission pattern, synaptic circuitry, etc under radiation exposure have more fundamental impact on organism systems (especially CNS and CVS) deterioration than simple radicals inflicted oxidative (nitrosative) damage of cellular constituents. Conclusions: This novel conceptualization of free-radical paradigm constitutes new dimension in deciphering molecular mechanisms of radiation effects on subtle borderline norm-pathology and continuity-discontinuity dichotomy in organisms systems disorders - CT(redox)omics, which involves investigation of CT, redox, and spin states of free radicals, DNA bases

  18. Theory of solvent effects on the hyperfine splitting constants in ESR spectra of free radicals

    International Nuclear Information System (INIS)

    Abe, T.; Tero-Kubota, S.; Ikegami, Y.

    1982-01-01

    An expression for the effects of solvation and hydrogen bonding on the hyperfine splitting constants of a free radical has been derived by obtaining π-electron spin densities of the radical in solution by perturbation theory. When no hydrogen bonding occurs between the radical and a solvent molecule, the splitting constant is approximately proportional to the Block and Walker parameter of theta(epsilon/sub r/) identical with 3 epsilon/sub r/ (ln epsilon/sub r/)/(epsilon/sub r/ ln epsilon/sub r/ - epsilon/sub r/ + 1) - 6/(ln epsilon/sub r/) - 2, where epsilon/sub r/ is the relative permittivity of the solvent. The expression is successfully applied to the di-tert-butyl nitroxide radical, the 1-methyl-4-(methoxycarbonyl)pyridinyl radical, and other free radicals. The effects of hydrogen bonding are discussed

  19. Free radical-scavenging delta-lactones from Boletus calopus.

    Science.gov (United States)

    Kim, Jin-Woo; Yoo, Ick-Dong; Kim, Won-Gon

    2006-12-01

    The methanol extracts from the fruiting body of the mushroom Boletus calopus showed free radical-scavenging activity. Bioactivity-guided fractionation of the methanol extracts led to a new hydroxylated calopin named calopin B, along with the known delta-lactones calopin and cyclocalopin A. The structure of the new calopin analogue was elucidated by spectroscopic methods. All compounds showed potent free radical-scavenging activity against superoxide, DPPH, and ABTS radicals with IC (50) values of 1.2 - 5.4 microg/mL.

  20. Selective free radical reactions using supercritical carbon dioxide.

    Science.gov (United States)

    Cormier, Philip J; Clarke, Ryan M; McFadden, Ryan M L; Ghandi, Khashayar

    2014-02-12

    We report herein a means to modify the reactivity of alkenes, and particularly to modify their selectivity toward reactions with nonpolar reactants (e.g., nonpolar free radicals) in supercritical carbon dioxide near the critical point. Rate constants for free radical addition of the light hydrogen isotope muonium to ethylene, vinylidene fluoride, and vinylidene chloride in supercritical carbon dioxide are compared over a range of pressures and temperatures. Near carbon dioxide's critical point, the addition to ethylene exhibits critical speeding up, while the halogenated analogues display critical slowing. This suggests that supercritical carbon dioxide as a solvent may be used to tune alkene chemistry in near-critical conditions.

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

    Directory of Open Access Journals (Sweden)

    Qiong Meng

    2012-06-01

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

  2. Effect of hydrogen pressure on free radicals in direct coal liquefaction/coprocessing

    Energy Technology Data Exchange (ETDEWEB)

    Seehra, M.S.; Ibrahim, M.M. [West Virginia Univ., Morgantown, WV (United States)

    1995-12-31

    The objective of this study was to investigate the coprocessing of coal with waste tires and commingled plastics and to characterize the relevant catalysts, using high pressure/high temperature in-situ ESR (Electron Spin Resonance) spectroscopy. The recent results from high pressure ESR spectroscopy are emphasized. During this period, considerable progress was made in developing the high pressure capabilities in in-situ ESR spectroscopy and new results carried out in 1000 psi of H{sub 2}gas are presented. In these experiments, sapphire tubes were used to contain the high pressures at temperatures up to 500{degrees}C. Results of the experiments carried out under 1000 psi of H{sub 2} are compared with those under 1000 psi of non-interacting argon and with the earlier experiments in flowing H{sub 2} gas where the volatiles are removed by the flowing gas. In these experiments, the free radical density N of the Blind Canyon coal was measured at each temperature and pressure by double integration of the ESR signal and calibrating it against a standard. The details of the experimental apparatus and procedures have been described in earlier publications.

  3. Evaluation of Antioxidant and Free Radical Scavenging Abilities of ...

    African Journals Online (AJOL)

    Objective: This study was aimed at determining the antioxidants and free radical scavenging abilities of some packaged fruit juices (PFJ) widely used as source of fluids in Nigeria. Materials and methods: Packaged fruit juice samples produced by The Coca cola Company and Chi company namely: Apple(AP), blackcurrant, ...

  4. Semiconductor processing apparatus with compact free radical source

    NARCIS (Netherlands)

    Kovalgin, Alexeij Y.; Aarnink, Antonius A.I.

    2013-01-01

    A semiconductor processing apparatus (1), comprising: a substrate processing chamber (158), defining a substrate support location (156) at which a generally planar semiconductor substrate (300) is supportable; and at least one free radical source (200), including: a precursor gas source (250); an

  5. Microbial fuel cell as a free-radical scavenging tool

    International Nuclear Information System (INIS)

    Koleva, Ralitza; Yemendzhiev, Hyusein; Nenov, Valentin

    2017-01-01

    Microbial fuel cells (MFCs) are known for their capability to directly convert organic substrates into electricity by the biochemical activity of specific microorganisms. Availability of a proper terminal electron acceptor is crucial for this process. Free radicals, with their one or more unpaired electrons, are extremely reducible and could be considered as electron acceptors in terms of cathodic processes in MFC. During this reduction, free radicals could be transformed in the same manner as they are transformed by antioxidants. The present study investigated this opportunity by utilization of 2,2-diphenyl-1-picrylhydrazyl (150 mmol/dm"3 methanol solution) as a free-radical molecule. During the studied process, over 90% radical neutralization was observed in less than 16 hours. The results obtained demonstrate for the first time the potential of MFC type bioelectrochemical systems to serve as a free-radical scavenging tool and to provide antioxidant and anti-radical activity. In this way, this study opens a completely new field of research and application of bio-electrochemical systems

  6. Free radical and thermal curing of terpyridine-modified terpolymers

    NARCIS (Netherlands)

    Hofmeier, H.; El-Ghayoury, A.; Schubert, U.S.

    2004-01-01

    Terpolymers bearing terpyridine as well as (meth)acrylates as free radical curable groups (UV-curing) or hydroxyl groups (thermal curing with bis-isocyanates) were synthesized and characterized using 1H NMR, IR and UV-vis spectroscopy as well as GPC. Subsequently, the ability of covalent

  7. Free Radical Scavenging Activities of Methanol Extract and ...

    African Journals Online (AJOL)

    Michael Horsfall

    fractions were subjected to in vitro antioxidant evaluation using the DPPH free radical scavenging ... The crude extract has IC-50 value for radical scavenging activity of 5μg/mL which was .... effective concentration of the sample that is required.

  8. Free radical scavenging activity and phenolic contents of ...

    African Journals Online (AJOL)

    Anthocleista djalonensis extract is widely used in Nigerian folk medicine to treat conditions whose pathogenesis implicate oxidative stress, such as diabetes and hepatitis. However, little is known of the mechanism underlying these activities. In this study, the free radical scavenging potential of a methanol extract of A.

  9. Effects of treatment on free radicals in patients with pulmonary ...

    African Journals Online (AJOL)

    Background: Formation of Malondialdehyde (MDA), a free radical, in Tuberculosis patients does occur when Tubercule bacilli induces ... All patients were screened for presence or absence of Mycobacterium tuberculosis in their sputum and. HIV 1 & 2 in .... fever, Diabetes Mellitus, patients with intestinal infec- tions which ...

  10. Chemical determination of free radical-induced damage to DNA.

    Science.gov (United States)

    Dizdaroglu, M

    1991-01-01

    Free radical-induced damage to DNA in vivo can result in deleterious biological consequences such as the initiation and promotion of cancer. Chemical characterization and quantitation of such DNA damage is essential for an understanding of its biological consequences and cellular repair. Methodologies incorporating the technique of gas chromatography/mass spectrometry (GC/MS) have been developed in recent years for measurement of free radical-induced DNA damage. The use of GC/MS with selected-ion monitoring (SIM) facilitates unequivocal identification and quantitation of a large number of products of all four DNA bases produced in DNA by reactions with hydroxyl radical, hydrated electron, and H atom. Hydroxyl radical-induced DNA-protein cross-links in mammalian chromatin, and products of the sugar moiety in DNA are also unequivocally identified and quantitated. The sensitivity and selectivity of the GC/MS-SIM technique enables the measurement of DNA base products even in isolated mammalian chromatin without the necessity of first isolating DNA, and despite the presence of histones. Recent results reviewed in this article demonstrate the usefulness of the GC/MS technique for chemical determination of free radical-induced DNA damage in DNA as well as in mammalian chromatin under a vast variety of conditions of free radical production.

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

    Czech Academy of Sciences Publication Activity Database

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

    2006-01-01

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

  12. Antioxidant and free radical scavenging activities of plant extracts ...

    African Journals Online (AJOL)

    Twenty-two species of medicinal plants collected in the Mexican state of Morelos were selected to evaluate their free radical scavenging and antioxidant activities. The extracts from the aerial parts of the plants were obtained using hexane, acetone and methanol (66 extracts). The initial qualitative screening of antioxidants ...

  13. Free radical scavenging activities of pigment extract from Hibiscus ...

    African Journals Online (AJOL)

    AJL

    2012-01-05

    Jan 5, 2012 ... molecules by getting electrons from them (Lien et al.,. 2008; Perry et al., ... of the filtrate was adjusted to 80% with 95% ethanol. The ..... Free Radical bio. Med. ... Antioxidant properties of banana flower of two cultivars in China using 2 ... total phenolic contents in peel and pulp of Chinese jujube (Ziziphus.

  14. Free radical scavenging potency of quercetin catecholic colonic metabolites: Thermodynamics of 2H+/2e- processes.

    Science.gov (United States)

    Amić, Ana; Lučić, Bono; Stepanić, Višnja; Marković, Zoran; Marković, Svetlana; Dimitrić Marković, Jasmina M; Amić, Dragan

    2017-03-01

    Reaction energetics of the double (2H + /2e - ), i.e., the first 1H + /1e - (catechol→ phenoxyl radical) and the second 1H + /1e - (phenoxyl radical→ quinone) free radical scavenging mechanisms of quercetin and its six colonic catecholic metabolites (caffeic acid, hydrocaffeic acid, homoprotocatechuic acid, protocatechuic acid, 4-methylcatechol, and catechol) were computationally studied using density functional theory, with the aim to estimate the antiradical potency of these molecules. We found that second hydrogen atom transfer (HAT) and second sequential proton loss electron transfer (SPLET) mechanisms are less energy demanding than the first ones indicating 2H + /2e - processes as inherent to catechol moiety. The Gibbs free energy change for reactions of inactivation of selected free radicals indicate that catecholic colonic metabolites constitute an efficient group of more potent scavengers than quercetin itself, able to deactivate various free radicals, under different biological conditions. They could be responsible for the health benefits associated with regular intake of flavonoid-rich diet. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Multiple free-radical scavenging capacity in serum

    Science.gov (United States)

    Oowada, Shigeru; Endo, Nobuyuki; Kameya, Hiromi; Shimmei, Masashi; Kotake, Yashige

    2012-01-01

    We have developed a method to determine serum scavenging-capacity profile against multiple free radical species, namely hydroxyl radical, superoxide radical, alkoxyl radical, alkylperoxyl radical, alkyl radical, and singlet oxygen. This method was applied to a cohort of chronic kidney disease patients. Each free radical species was produced with a common experimental procedure; i.e., uv/visible-light photolysis of free-radical precursor/sensitizer. The decrease in free-radical concentration by the presence of serum was quantified with electron spin resonance spin trapping method, from which the scavenging capacity was calculated. There was a significant capacity change in the disease group (n = 45) as compared with the healthy control group (n = 30). The percent values of disease’s scavenging capacity with respect to control group indicated statistically significant differences in all free-radical species except alkylperoxyl radical, i.e., hydroxyl radical, 73 ± 12% (p = 0.001); superoxide radical, 158 ± 50% (p = 0.001); alkoxyl radical, 121 ± 30% (p = 0.005); alkylperoxyl radical, 123 ± 32% (p>0.1); alkyl radical, 26 ± 14% (p = 0.001); and singlet oxygen, 57 ± 18% (p = 0.001). The scavenging capacity profile was illustrated using a radar chart, clearly demonstrating the characteristic change in the disease group. Although the cause of the scavenging capacity change by the disease state is not completely understood, the profile of multiple radical scavenging capacities may become a useful diagnostic tool. PMID:22962529

  16. Free radical scavenging injectable hydrogels for regenerative therapy

    International Nuclear Information System (INIS)

    Komeri, Remya; Thankam, Finosh Gnanaprakasam; Muthu, Jayabalan

    2017-01-01

    Pathological free radicals generated from inflamed and infarcted cardiac tissues interferes natural tissue repair mechanisms. Hypoxic microenvironment at the injured zone of non-regenerating cardiac tissues hinders the therapeutic attempts including cell therapy. Here we report an injectable, cytocompatible, free radical scavenging synthetic hydrogel formulation for regenerative therapy. New hydrogel (PEAX-P) is prepared with D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer (PEAX) and PEGDiacrylate. PEAX-P hydrogel swells 4.9 times the initial weight and retains 100.07 kPa Young modulus at equilibrium swelling, which is suitable for cardiac applications. PEAX-P hydrogel retains elastic nature even at 60% compressive strain, which is favorable to fit with the dynamic and elastic natural tissue counterparts. PEAX-P hydrogel scavenges 51% DPPH radical, 40% hydroxyl radicals 41% nitrate radicals with 31% reducing power. The presence of hydrogel protects 62% cardiomyoblast cells treated with stress inducing media at LD 50 concentration. The free hydroxyl groups in sugar alcohols of the comacromer influence the free radical scavenging. Comparatively, PEAX-P hydrogel based on xylitol evinces slightly lower scavenging characteristics than with previously reported PEAM-P hydrogel containing mannitol having more hydroxyl groups. The possible free radical scavenging mechanism of the present hydrogel relies on the free π electrons associated with uncrosslinked fumarate bonds, hydrogen atoms associated with sugar alcohols/PEG and radical dilution by free water in the matrix. Briefly, the present PEAX-P hydrogel is a potential injectable system for combined antioxidant and regenerative therapy. - Graphical abstract: Injectable hydrogel with inherent free radical scavenging property for regenerative tissue engineering application. - Highlights: • Novel injectable hydrogel (PEAX-P) is prepared using D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer

  17. Free radical scavenging injectable hydrogels for regenerative therapy

    Energy Technology Data Exchange (ETDEWEB)

    Komeri, Remya [Sree Chitra Tirunal Institute for Medical Sciences and Technology, Polymer Science Division, BMT Wing, Thiruvananthapuram 695 012, Kerala State (India); Thankam, Finosh Gnanaprakasam [Dept. of Biomedical Sciences, Creighton University, 2500 California Plaza, Omaha NE68178 (United States); Muthu, Jayabalan, E-mail: mjayabalan52@gmail.com [Sree Chitra Tirunal Institute for Medical Sciences and Technology, Polymer Science Division, BMT Wing, Thiruvananthapuram 695 012, Kerala State (India)

    2017-02-01

    Pathological free radicals generated from inflamed and infarcted cardiac tissues interferes natural tissue repair mechanisms. Hypoxic microenvironment at the injured zone of non-regenerating cardiac tissues hinders the therapeutic attempts including cell therapy. Here we report an injectable, cytocompatible, free radical scavenging synthetic hydrogel formulation for regenerative therapy. New hydrogel (PEAX-P) is prepared with D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer (PEAX) and PEGDiacrylate. PEAX-P hydrogel swells 4.9 times the initial weight and retains 100.07 kPa Young modulus at equilibrium swelling, which is suitable for cardiac applications. PEAX-P hydrogel retains elastic nature even at 60% compressive strain, which is favorable to fit with the dynamic and elastic natural tissue counterparts. PEAX-P hydrogel scavenges 51% DPPH radical, 40% hydroxyl radicals 41% nitrate radicals with 31% reducing power. The presence of hydrogel protects 62% cardiomyoblast cells treated with stress inducing media at LD 50 concentration. The free hydroxyl groups in sugar alcohols of the comacromer influence the free radical scavenging. Comparatively, PEAX-P hydrogel based on xylitol evinces slightly lower scavenging characteristics than with previously reported PEAM-P hydrogel containing mannitol having more hydroxyl groups. The possible free radical scavenging mechanism of the present hydrogel relies on the free π electrons associated with uncrosslinked fumarate bonds, hydrogen atoms associated with sugar alcohols/PEG and radical dilution by free water in the matrix. Briefly, the present PEAX-P hydrogel is a potential injectable system for combined antioxidant and regenerative therapy. - Graphical abstract: Injectable hydrogel with inherent free radical scavenging property for regenerative tissue engineering application. - Highlights: • Novel injectable hydrogel (PEAX-P) is prepared using D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer

  18. EPR assessment of the free radicals in irradiated foodstuffs

    International Nuclear Information System (INIS)

    Tencheva, S.; Katsareva, Ts.; Malinovski, A.; Kabasanov, K.

    1985-01-01

    In the hygienic assessment of radiation treated foodstuffs the study of free radicals formed during radiation exposure, their concentration and disintegration kinetics are of particular interest. In the work presented the concentration of the free radicals in irradiated prunes, nuts and corn is determined using EPR spectroscopy. The following doses are applied: 2, 10 and 20 kGy for prunes, 1, 10 and 20 kGy for nuts, and 0.75, 10 and 20 kGy for corn. EPR measurements are done immediately after the irradiation: 24 hours, and 3, 6, 9 and 15 days after the exposure. In the small radiation doses the formation of single radicals is observed. In doses of 10 kGy the spectra get complicated with the occurence of radicals R 1 , R 2 , R 3 and R 4 . The assessment of radicals proves to be a prospective method for the identification and determination of the preservation terms of foodstuffs

  19. Reactions of inorganic free radicals with liver protecting drugs

    International Nuclear Information System (INIS)

    Gyoergy, I.; Foeldiak, G.; Blazovics, A.; Feher, J.

    1990-01-01

    Liver protecting drugs, silibinin, a flavonolignane, and the dihydroquinoline derivatives, CH 402 and MTDQ-DA, were shown to inhibit processes in which enzymatically or non-enzymatically generated free radicals were involved. Inorganic free radicals (N 3 , (SCN) 2 - , OH, Trp, CO 2 - , O 2 - ) produced by pulse radiolysis readily react with the compounds, which transform into exceptionally long-lived, unreactive transients. Time evolution of the UV and visible spectra indicate that oxidising radicals form a phenoxyl type radical from silibinin, while OH forms an adduct by attacking, simultaneously, at various sites of the molecule. Superoxide radicals reduce silibinin and oxidise CH 402 and MTDQ-DA. It is concluded that the drugs might exhibit antioxidant behavior in living systems. (author)

  20. Preparing polymer brushes on polytetrafluoroethylene films by free radical polymerization

    International Nuclear Information System (INIS)

    Sun Wei; Chen Yiwang; Deng Qilan; Chen Lie; Zhou Lang

    2006-01-01

    Films of polytetrafluoroethylene (PTFE) were exposed to sodium naphthalenide (Na/naphtha) etchant so as to defluorinate the surface for obtaining hydroxyl functionality. Surface-initiators were immobilized on the PTFE films by esterification of 4,4'-azobis(4-cyanopentanoic acid) (ACP) and the hydroxyl groups covalently linked to the surface. Grafting of polymer brushes on the PTFE films was carried out by the surface-initiated free radical polymerization. Homopolymers brushes of methyl methacrylate (MMA) were prepared by free radical polymerization from the azo-functionalized PTFE surface. The chemical composition and topography of the graft-functionalized PTFE surfaces were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance (ATR) FT-IR spectroscopy and atomic force microscopy (AFM). Water contact angles on PTFE films were reduced by surface grafting of MMA

  1. Resonance Raman Spectroscopy of Free Radicals Produced by Ionizing Radiation

    DEFF Research Database (Denmark)

    Wilbrandt, Robert Walter

    1984-01-01

    Applications of time-resolved resonance Raman spectroscopy to the study of short-lived free radicals produced by ionizing radiation are briefly reviewed. Potential advantages and limitations of this technique are discussed in the light of given examples. The reduction of p-nitrobenzylchloride and......Applications of time-resolved resonance Raman spectroscopy to the study of short-lived free radicals produced by ionizing radiation are briefly reviewed. Potential advantages and limitations of this technique are discussed in the light of given examples. The reduction of p......-nitrobenzylchloride and subsequent formation of the p-nitrobenzyl radical and the reaction of p-nitrotoluene with O– are studied by resonance Raman and optical absorption spectroscopy....

  2. 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.

  3. Free radical scavenging injectable hydrogels for regenerative therapy.

    Science.gov (United States)

    Komeri, Remya; Thankam, Finosh Gnanaprakasam; Muthu, Jayabalan

    2017-02-01

    Pathological free radicals generated from inflamed and infarcted cardiac tissues interferes natural tissue repair mechanisms. Hypoxic microenvironment at the injured zone of non-regenerating cardiac tissues hinders the therapeutic attempts including cell therapy. Here we report an injectable, cytocompatible, free radical scavenging synthetic hydrogel formulation for regenerative therapy. New hydrogel (PEAX-P) is prepared with D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer (PEAX) and PEGDiacrylate. PEAX-P hydrogel swells 4.9 times the initial weight and retains 100.07kPa Young modulus at equilibrium swelling, which is suitable for cardiac applications. PEAX-P hydrogel retains elastic nature even at 60% compressive strain, which is favorable to fit with the dynamic and elastic natural tissue counterparts. PEAX-P hydrogel scavenges 51% DPPH radical, 40% hydroxyl radicals 41% nitrate radicals with 31% reducing power. The presence of hydrogel protects 62% cardiomyoblast cells treated with stress inducing media at LD 50 concentration. The free hydroxyl groups in sugar alcohols of the comacromer influence the free radical scavenging. Comparatively, PEAX-P hydrogel based on xylitol evinces slightly lower scavenging characteristics than with previously reported PEAM-P hydrogel containing mannitol having more hydroxyl groups. The possible free radical scavenging mechanism of the present hydrogel relies on the free π electrons associated with uncrosslinked fumarate bonds, hydrogen atoms associated with sugar alcohols/PEG and radical dilution by free water in the matrix. Briefly, the present PEAX-P hydrogel is a potential injectable system for combined antioxidant and regenerative therapy. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Free radical reactions of hematoporphyrin: a pulse radiolysis study

    International Nuclear Information System (INIS)

    Ahmed, Mohammed; Guleria, Apurav; Singh, Ajay K.; Sarkar, S.K.

    2011-01-01

    Radiation chemistry of porphyrin derivatives has been given much attention in recent years. Although till date photo dynamic therapy (PDT) with Hematoporphyrin (HP) has already proved its effectiveness in the treatment of cancer, the molecular mechanisms by which this therapy-destroys tumour cells as well as its optimal physical parameters are still not fully understood. Thus it becomes necessary to understand the interaction of different free radicals with HP. Pulse radiolysis studies have been performed to understand the interaction of different free radicals with HP. The product formation along with bleaching and presence of a number of transients makes it difficult to pin point the mode and site of free radical attack. The radiation-induced formation of various transients (HP-OH, HO - , HP + ) in aqueous solution was investigated at various pHs by pulse radiolysis technique by means of N 3 , O - and CCl 3 O 2 radicals with and without triethyl-amine, under different dose conditions. The observed intermediates are characterized by their kinetic and spectroscopic data. The absorption spectrum of each transient could be differentiated from each other by their absorption maxima, extinction coefficients and kinetics. A clear indication of product formation has also been observed by employing continuous electron pulse and the solution shows a green coloration. It is conceivable that under certain conditions, similar transients may be produced when HP is used as a sensitizer in radiation chemotherapy of cancer patients. Our study may throw some light into the breakdown mechanism of haemoglobin to BV in addition to the understanding of free radical interaction of HP. (author)

  5. Phytochemical Screening and Free Radical Scavenging Activities of ...

    African Journals Online (AJOL)

    Total phenolic, total flavonoid and proanthocyanidin contents were 65, 0.07 and 2.38 mg/g of powdered plant material for AF fruits, and 12, 51.35, 19.5 mg/g of powdered plant material for AF leaves as gallic acid, rutin and catechin equivalents respectively. Conclusion: AF leaves are five times more potent as a free radical ...

  6. Investigation of free radicals in paprika with the ESR method

    International Nuclear Information System (INIS)

    Kispeter, J.; Szabo, I.; Horvath, L.J.

    1998-01-01

    Complete text of publication follows. The ESR method is the one of the most successfully applied method among the physical methods for the identification of radiation or ionising treatment of foods. The identification of free radicals having short and long lifetimes is the base of the measurement. The quantitative determination makes possible the determination of the absorbed dose deriving from 60 Co radiation treatment. It has to be noted that the treatment of the foods with ionising radiation and other treatments (milling, frying, baking) and the oxidative process result free radicals in paprika samples as a function of absorbed radiation dose (2.5; 5 and 10 kGy) on the different particle size and on storage time. The intensities of the samples given after each of the seven stages of the paprika milling increased till the fifth stage corresponding to the effect of a 2 kGy absorbed dose. After conditioning and increasing the water content by 5-8% the ESR intensity shows significant lowering. This value characterises the ESR intensity of not irradiated sample. As an effect of the irradiation the ESR intensities increased along with the increase of the absorbed dose. The samples having lower particle size are more sensible for the identification of the irradiation. Evaluating the art of the decline we concluded that there are free radicals having short and long shelf lifetimes in paprika samples at the same time

  7. Bergenin Content and Free Radical Scavenging Activity of Bergenia Extracts. .

    Science.gov (United States)

    Hendrychová, Helena; Martin, Jan; Tůmová, Lenka; Kočevar-Glavač, Nina

    2015-07-01

    Our research was focused on the evaluation of bergenin content and free radical scavenging activity of extracts prepared from three different species of Bergenia - B. crassifolia (L.) Fritsch., B. ciliata (Haw.) Sternb. and B. x ornata Stein. collected during different seasons. Using an HPLC method, the highest total amount of bergenin was revealed in the leaves of B. x ornata and B. crassifolia (4.9 - 5.1 mg x g(-1)). Free radical scavenging power was determined by two methods--FRAP and NADH. The best free radical scavengers were B. crassifolia (FRAP: 6.7 - 15.9 mg GAE. 100g(-1); NADH: 20.3 - 50.9%) and B. ornata (FRAP: 13.7 - 15.2 mg GAE. 100g(-1); NADH: 29.3 - 31.1%). The lowest content of bergenin and the weakest radical scavenger was B. ciliata (bergenin: 3.1 mg x g(-1); FRAP: 5.5 - 11.0 mg GAE.100g(-1); NADH: 23.2 - 25.6%). The presence of a large percentage of bergenin is responsible for the radical scavenging activity, as shown by the results from the FRAP and NADH assays. Significant, positive correlation was found between bergenin content and radical scavenging activity in both methods.

  8. Free radicals in cellulose containing food detected by ESR

    International Nuclear Information System (INIS)

    Abe, Aika; Yogo, Satsuki; Ichii, Akane; Ukai, Mitsuko

    2003-01-01

    Using electron spin resonance (ESR) spectroscopy, we revealed three radical species in cellulose containing foods, pepper and green tea. These are commercially available in Japan. The representative ESR spectrum is composed of a sextet centered at g=2.0, a singlet at the same g-value, and a singlet at g=4.0. The first one is attributable to a signal with hyperfine (hf) interactions of Mn 2+ ion (hf constant: 7.4 mT). The second one is due to an organic free radical, the third one may be originated from Fe 3+ ion. The progressive saturation behavior (PSB) of the ESR at various microwave power levels were indicated different relaxation behaviors of in those radicals. Namely, the peak intensity of the organic free radical component decreases in a monotonic fashion, whereas the Mn 2+ and Fe 3+ ESR signals substantially keep constant. This reflects the evidence of three independent radical species. The ESR spectrum of the cellulose containing foods shows the same spectral feature irrespective of the tea or pepper. Upon gamma irradiation, a new pair of signals appeared. The PSB of the pair peaks after the irradiation showed a quite different as compared with the free radical centered at g=2. (author)

  9. Redox potentials of free radicals. III. Reevaluation of the method

    International Nuclear Information System (INIS)

    Rao, P.S.; Hayon, E.

    1974-01-01

    A reevaluation of the method described in ref 1 and 2 to determine the redox potentials of free radicals (.RH) in water using the techniques of pulse radiolysis and absorption spectrophotometry is presented. This method is based on the dependence of the percentage efficiency for the one-electron oxidation (or reduction) of .RH radicals on the redox potentials E 01 of the electron acceptors, A. The reaction .RH + A → .A - + R + H + (kappa/sub ox/) is not reversible for most radicals under the experimental conditions used, and the derived potentials are, therefore, not thermodynamic values. A reinterpretation of the results is made on the basis of the kinetic competition between the above reaction and .RH + A → .RHA (kappa/sub add/) (radical adducts). Based on kappa/ sub ox/ and kappa/sub add/, it is concluded that the observed experimental ''titration'' curves do represent a measure of the redox property of the free radicals. From the midpoint on the curves, the kinetic potential, E/sub kappa/ 01 : of the free radicals can be derived based on the known two-electron redox potentials of the electron acceptors. These and other questions are discussed. (U.S.)

  10. Theoretical insights on the antioxidant activity of edaravone free radical scavengers derivatives

    Science.gov (United States)

    Cerón-Carrasco, José P.; Roy, Hélène M.; Cerezo, Javier; Jacquemin, Denis; Laurent, Adèle D.

    2014-04-01

    The prediction of antioxidant properties is not straightforward due to the complexity of the in vivo systems. Here, we use theoretical descriptors, including the potential of ionization, the electrodonating power and the spin density distribution, to characterize the antioxidant capacity of edaravone (EDV) derivatives. Our computations reveal the relationship between these parameters and their potential bioactivity as free radical scavengers. We conclude that more efficient antioxidants could be synthesized by tuning the R1 and R2 positions of the EDV structure, rather than modifying the R3 group. Such modifications might improve the antioxidant activity in neutral and deprotonated forms.

  11. Abstracts of 2. symposium on free radicals in biology and medicine

    International Nuclear Information System (INIS)

    1994-01-01

    The abstracts presented in the booklet concern influence of free radicals (frequently generated by ionizing radiation) on DNA, proteins, lipids and chromatin of various living organisms. Works show, that free radicals cause serious damages in biological systems leading to carcinogenesis and many genetic diseases. Thus understanding of mechanisms of free radical action is important issue in medicine and life sciences

  12. Abstracts of 2. symposium on free radicals in biology and medicine

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-12-31

    The abstracts presented in the booklet concern influence of free radicals (frequently generated by ionizing radiation) on DNA, proteins, lipids and chromatin of various living organisms. Works show, that free radicals cause serious damages in biological systems leading to carcinogenesis and many genetic diseases. Thus understanding of mechanisms of free radical action is important issue in medicine and life sciences.

  13. Temperature Effects on Free Radicals in Gamma-sterilized Beef

    Science.gov (United States)

    Pramanik, S. I.; Jahan, M. S.

    1999-11-01

    Gamma irradiation has become the method of choice for sterilizing frozen meat and their products to reduce levels of food-borne pathogens and to extend shelf life. In this report we have employed ESR technique for detection of free radicals in sterilized and non-sterilized dry beef without bone. We have also determined the heating effects on free radicals at temperatures 176^°C and 250^°C. Meat samples were dried in a food dehydrator at 60^°C and were packaged in dry N_2. They were then sterilized by γ-irradiation (2.5 MRad), ground into powder, and placed in ESR sample tubes. Non-sterilized powder samples were used as control. While all powder samples, sterilized or not, produced a broad single line in the ESR spectra with (Δ H_pp ~ 9 G) and g = 2.013, the radical concentration in the sterilized samples increased by a factor of five. Heat treatment at 176^°C produced similar radicals. But, when samples were heated 250^°C different radical species were formed which are characterized by narrow width (Δ H_pp ~ 6 G) and lower g-value (g =2.010). In contrast with previous work, where free radicals in chicken bones were reduced by heating [1], we observed an increase in concentration. Results of structural analyses of the radicals will be presented. Ref.[1]: Radiat. Phys. Chem., 49, 477-481, 1997. Work supported by Grants from the University of Memphis

  14. Role of free radicals in radiation chemical aging

    Energy Technology Data Exchange (ETDEWEB)

    Greenstock, C L

    1986-01-01

    Ionizing radiation initiates chemical changes in DNA, phospholipid membranes and other critical cell targets, that, if allowed to accumulate unrepaired, may lead to aging and other chronic effects. The chemical effects are free radical mediated, the principal damaging species being radical OH and to a lesser extent O2-anion radical and the molecular product H/sub 2/O/sub 2/. Many compounds can act in combination with ionizing radiation, to amplify the potential oxidative stress. Chemicals, ultra-violet light, lipid peroxides and their breakdown products may increase the extent of acute and chronic radiobiological effects.

  15. Molybdenum disulfide for ultra-low detection of free radicals: electrochemical response and molecular modeling

    Science.gov (United States)

    Gupta, Ankur; Rawal, Takat B.; Neal, Craig J.; Das, Soumen; Rahman, Talat S.; Seal, Sudipta

    2017-06-01

    Two-dimensional (2D) molybdenum disulfide (MoS2) offers attractive properties due to its band gap modulation and has led to significant research-oriented applications (i.e. DNA and protein detection, cell imaging (fluorescent label) etc.). In biology, detection of free radicals (i.e. reactive oxygen species and reactive nitrogen (NO*) species are very important for early discovery and treatment of diseases. Herein, for the first time, we demonstrate the ultra-low (pico-molar) detection of pharmaceutically relevant free radicals using MoS2 for electrochemical sensing. We present pico- to nano- molar level sensitivity in smaller MoS2 with S-deficiency as revealed by x-ray photoelectron spectroscopy. Furthermore, the detection mechanism and size-dependent sensitivity have been investigated by density functional theory (DFT) showing the change in electronic density of states of Mo atoms at edges which lead to the preferred adsorption of H2O2 on Mo edges. The DFT analysis signifies the role of size and S-deficiency in the higher catalytic activity of smaller MoS2 particles and, thus, ultra-low detection.

  16. Habitat of in vivo transformation influences the levels of free radical scavengers in Clinostomum complanatum: implications for free radical scavenger based vaccines against trematode infections.

    Science.gov (United States)

    Zafar, Atif; Rizvi, Asim; Ahmad, Irshad; Ahmad, Masood

    2014-01-01

    Since free radical scavengers of parasite origin like glutathione-S-transferase and superoxide dismutase are being explored as prospective vaccine targets, availability of these molecules within the parasite infecting different hosts as well as different sites of infection is of considerable importance. Using Clinostomum complanatum, as a model helminth parasite, we analysed the effects of habitat of in vivo transformation on free radical scavengers of this trematode parasite. Using three different animal models for in vivo transformation and markedly different sites of infection, progenetic metacercaria of C. complanatum were transformed to adult ovigerous worms. Whole worm homogenates were used to estimate the levels of lipid peroxidation, a marker of oxidative stress and free radical scavengers. Site of in vivo transformation was found to drastically affect the levels of free radical scavengers in this model trematode parasite. It was observed that oxygen availability at the site of infection probably influences levels of free radical scavengers in trematode parasites. This is the first report showing that habitat of in vivo transformation affects levels of free radical scavengers in trematode parasites. Since free radical scavengers are prospective vaccine targets and parasite infection at ectopic sites is common, we propose that infections at different sites, may respond differently to free radical scavenger based vaccines.

  17. A multiple free-radical scavenging (MULTIS) study on the antioxidant capacity of a neuroprotective drug, edaravone as compared with uric acid, glutathione, and trolox.

    Science.gov (United States)

    Kamogawa, Erisa; Sueishi, Yoshimi

    2014-03-01

    Edaravone (3-methyl-1-phenyl-2-pyrazoline-5-one) is a neuroprotective drug that has been used for brain ischemia injury treatment. Because its activity is speculated to be due to free radical scavenging activity, we carried out a quantitative determination of edaravone's free radical scavenging activity against multiple free radical species. Electron spin resonance (ESR) spin trapping-based multiple free-radical scavenging (MULTIS) method was employed, where target free radicals were hydroxyl radical, superoxide anion, alkoxyl radical, alkylperoxyl radical, methyl radical, and singlet oxygen. Edaravone showed relatively high scavenging abilities against hydroxyl radical (scavenging rate constant k=2.98×10(11) M(-1) s(-1)), singlet oxygen (k=2.75×10(7) M(-1) s(-1)), and methyl radical (k=3.00×10(7) M(-1) s(-1)). Overall, edaravone's scavenging activity against multiple free radical species is as robust as other known potent antioxidant such as uric acid, glutathione, and trolox. A radar chart illustration of the MULTIS activity relative to uric acid, glutathione, and trolox indicates that edaravone has a high and balanced antioxidant activity with low specificity. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Synthesis and Free Radical Scavenging Activity of New Hydroxybenzylidene Hydrazines

    Directory of Open Access Journals (Sweden)

    Frantisek Sersen

    2017-05-01

    Full Text Available Hydroxybenzylidene hydrazines exhibit a wide spectrum of biological activities. Here, we report synthesis and free radical scavenging activity of nine new N-(hydroxybenzylidene-N′-[2,6-dinitro-4-(trifluoromethyl]phenylhydrazines. The chemical structures of these compounds were confirmed by 1H-NMR, 13C-NMR, 19F-NMR, IR spectroscopy, LC-MS, and elemental analysis. The prepared compounds were tested for their activity to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH, galvinoxyl radical (GOR, and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS radicals. The free radical scavenging activity expressed as SC50 values of these compounds varied in a wide range, from a strong to no radical scavenging effect. The most effective radical scavengers were hydroxybenzylidene hydrazines containing three hydroxyl groups in the benzylidene part of their molecules. The prepared compounds were also tested for their activity to inhibit photosynthetic electron transport in spinach chloroplasts. IC50 values of these compounds varied in wide range, from an intermediate to no inhibitory effect.

  19. Synthesis and Free Radical Scavenging Activity of New Hydroxybenzylidene Hydrazines.

    Science.gov (United States)

    Sersen, Frantisek; Gregan, Fridrich; Kotora, Peter; Kmetova, Jarmila; Filo, Juraj; Loos, Dusan; Gregan, Juraj

    2017-05-29

    Hydroxybenzylidene hydrazines exhibit a wide spectrum of biological activities. Here, we report synthesis and free radical scavenging activity of nine new N-(hydroxybenzylidene)-N'-[2,6-dinitro-4-(trifluoromethyl)]phenylhydrazines. The chemical structures of these compounds were confirmed by 1H-NMR, 13C-NMR, 19F-NMR, IR spectroscopy, LC-MS, and elemental analysis. The prepared compounds were tested for their activity to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH), galvinoxyl radical (GOR), and 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulphonic acid (ABTS) radicals. The free radical scavenging activity expressed as SC50 values of these compounds varied in a wide range, from a strong to no radical scavenging effect. The most effective radical scavengers were hydroxybenzylidene hydrazines containing three hydroxyl groups in the benzylidene part of their molecules. The prepared compounds were also tested for their activity to inhibit photosynthetic electron transport in spinach chloroplasts. IC50 values of these compounds varied in wide range, from an intermediate to no inhibitory effect.

  20. Multiple free-radical scavenging (MULTIS) capacity in cattle serum.

    Science.gov (United States)

    Sueishi, Yoshimi; Kamogawa, Erisa; Kimura, Anna; Kitahara, Go; Satoh, Hiroyuki; Asanuma, Taketoshi; Oowada, Shigeru

    2017-01-01

    Multiple free-radical scavenging (MULTIS) activity in cattle and human sera was evaluated with electron spin resonance spectroscopy. Scavenging rates against six active species, namely hydroxyl radical, superoxide anion, alkoxyl radical, alkylperoxyl radical, methyl radical, and singlet oxygen were quantified. The difference in the electron spin resonance signal intensity in the presence and absence of the serum was converted into the scavenging rates. Comparative MULTIS measurements were made in sera from eight beef cattle, three fetal calves and fifteen healthy human volunteers. Further, we determined the MULTIS value of albumin, the most abundant component in serum. MULTIS values in cattle sera indicated higher scavenging activity against most free radical species tested than human sera. In particular, cattle serum scavenging activities against superoxide and methyl radical were higher than human serum by 2.6 and 3.7 fold, respectively. In cattle serum, albumin appears to play a dominant role in MULTIS activity, but in human serum that is not the case. Previous data indicated that the abundance of uric acid in bovine blood is nearly 80% less than humans; however, this difference does not explain the deviation in MULTIS profile.

  1. IRON AND FREE RADICAL OXIDATIONS IN CELL MEMBRANES

    Science.gov (United States)

    Schafer, Freya Q.; Yue Qian, Steven; Buettner, Garry R.

    2013-01-01

    Brain tissue being rich in polyunsaturated fatty acids, is very susceptible to lipid peroxidation. Iron is well known to be an important initiator of free radical oxidations. We propose that the principal route to iron-mediated lipid peroxidations is via iron-oxygen complexes rather than the reaction of iron with hydrogen peroxide, the Fenton reaction. To test this hypothesis, we enriched leukemia cells (K-562 and L1210 cells) with docosahexaenoic acid (DHA) as a model for brain tissue, increasing the amount of DHA from approximately 3 mole % to 32 mole %. These cells were then subjected to ferrous iron and dioxygen to initiate lipid peroxidation in the presence or absence of hydrogen peroxide. Lipid-derived radicals were detected using EPR spin trapping with α-(4-pyridyl-1-oxide)-N-t-butylnitrone (POBN). As expected, lipid-derived radical formation increases with increasing cellular lipid unsaturation. Experiments with Desferal demonstrate that iron is required for the formation of lipid radicals from these cells. Addition of iron to DHA-enriched L1210 cells resulted in significant amounts of radical formation; radical formation increased with increasing amount of iron. However, the exposure of cells to hydrogen peroxide before the addition of ferrous iron did not increase cellular radical formation, but actually decreased spin adduct formation. These data suggest that iron-oxygen complexes are the primary route to the initiation of biological free radical oxidations. This model proposes a mechanism to explain how catalytic iron in brain tissue can be so destructive. PMID:10872752

  2. Hormonal shifts and intensity of free radical oxidation in the blood of patients with facial nerve neuropathies

    Directory of Open Access Journals (Sweden)

    L. V. Govorova

    2010-01-01

    Full Text Available Pathochemical characteristic features of facial nerve neuropathy (FNN have been more accurately defined. Heterogeneous patochemical pattern of facial nerve neuropathy has been shown to be dependent on the severity of the disease, intensity of free radical oxidation processes, and hormonal status of the patient. We have found reliable distinctions in dynamics of free radical oxidation processes, and hormo-nal status in the blood of the patients with moderately severe and severe forms of facial nerve neuropathies. In facial nerve neuropathies we observed regulatory effects of cortisol and somatotropic hormone; in facial nerve neuropathywith moderate severity the hormones of thyroid group were seen to be switching off, falling out the processes regulating metabolism. Follicle stimulating hormone (FSH and luteinizing hormone (LH were found to have regulating effects, especially in the acute phase of the disease. Different dynamics of the hormones in patients with high and low free radical oxidation levels suggests that the oxidative stress intensity could be associated with regulatory effects of the hormones . The results of correlation analysis confirm the reliable distinctions in free radical oxidation characteristics andand cortisole levels, STH, FSH and LH levels.

  3. Optimization of free radical scavenging capacity and pH of Hylocereus polyrhizus peel by Response Surface Methodology

    Science.gov (United States)

    Putranto, A. W.; Dewi, S. R.; Puspitasari, Y.; Nuriah, F. A.

    2018-03-01

    Red dragon fruit (Hylocereus polyrhizus) peel, a by-product of juice processing, contains a high antioxidant that can be used for nutraceuticals. Hence, it is important to extract and investigate its antioxidant stability. The aim of this study was to optimize the free radical scavenging capacity and pH of H. polyrhizus peel extract using Central Composite Design (CCD) under Response Surface Methodology (RSM). The extraction of H. polyrhizus peel was done by using green-Pulsed Electric Field (PEF)-assisted extraction method. Factors optimized were electric field strength (kV/cm) and extraction time (seconds). The result showed that the correlation between responses (free radical-scavenging capacity and pH) and two factors was quadratic model. The optimum conditions was obtained at the electric field strength of 3.96 kV/cm, and treatment time of 31.9 seconds. Under these conditions, the actual free radical-scavenging capacity and pH were 75.86 ± 0.2 % and 4.8, respectively. The verification model showed that the actual values are in accordance with the predicted values, and have error rate values of free radical-scavenging capacity and pH responses were 0.1% and 3.98%, respectively. We suggest to extract the H. polyrhizus peel using a green and non-thermal extraction technology, PEF-assisted extraction, for research, food applications and nutraceuticals industry.

  4. Differential radioprotection and free radical scavenging activity of Caesalpinia digyna extracts and the active constituent

    International Nuclear Information System (INIS)

    Singh, Umang; Kunwar, A.; Barik, A.; Priyadarsini, K.I.; Mula, S.; Srinivasan, R.

    2008-01-01

    Differential free radical activity of the fractionated extracts (F1: methanolic fraction, F2: acetone soluble fraction and F3: acetone insoluble fraction) of a medicinal plant Caesalpinia digyna, has been studied employing DPPH, superoxide radical and in vitro radioprotecting activity by following their effect on radiation induced protein carbonylation and DNA damage in pBR322. The activity for these fractions is in the order of F1>F2>F3. HPLC analysis indicated that all fractions contain high amount of bergenin, a polyhydroxy isocoumarin derivative and the fractions are more active than isolated bergenin. (author)

  5. Differential radioprotection and free radical scavenging activity of Caesalpinia digyna extracts and the active constituent

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Umang; Kunwar, A; Barik, A; Priyadarsini, K I [Radiation and Photochemistry Div., Bhabha Atomic Research Centre, Mumbai (India); Mula, S [Bio-Organic Div., Bhabha Atomic Research Centre, Mumbai (India); Srinivasan, R [JSS College of Pharmacy, Ootacamund (India)

    2008-01-15

    Differential free radical activity of the fractionated extracts (F1: methanolic fraction, F2: acetone soluble fraction and F3: acetone insoluble fraction) of a medicinal plant Caesalpinia digyna, has been studied employing DPPH, superoxide radical and in vitro radioprotecting activity by following their effect on radiation induced protein carbonylation and DNA damage in pBR322. The activity for these fractions is in the order of F1>F2>F3. HPLC analysis indicated that all fractions contain high amount of bergenin, a polyhydroxy isocoumarin derivative and the fractions are more active than isolated bergenin. (author)

  6. Evaluation of free radical scavenging capacity and antioxidative damage effect of resveratrol-nanostructured lipid carriers

    Science.gov (United States)

    Jin, Ju; Shi, Fan; Li, Qiu-wen; Li, Pei-shan; Chen, Tong-sheng; Wang, Yi-fei; Wang, Zhi-ping

    2016-03-01

    Cellular damage induced by free-radicals like reactive oxygen species has been implicated in several diseases. 2, 2-azobis(2-amidino-propane) dihydrochloride(AAPH) generates two potent ROS capable of inducing lipid peroxidation: alkoxy radical(RO-) and peroxy radical(ROO-). These radicals are similar to those that are physiologically active and thus might initiate a cascade of intracellular toxic events leading to oxidation, lipid peroxidation, DNA damage and subsequent cell death. Hence naturally anti-oxidant play a vital role in combating these conditions. In this study, resveratrol loaded nanostructured lipid carriers (Res-NLC) was prepared by hot melting and then high pressure homogenization technique. The effects of Res-NLC on free radical scavenging capacity and antioxidative damage is investigated. The particle size and zeta potential of Res-NLC were 139.3 ± 1.7 nm and -11.21 ± 0.41 mV, respectively. By free radical scavenging assays, the IC50 value of Res-NLC were 19.25, 5.29 μg/mL with DPPH, ABTS assay respectively, and 0.161 mg ferrous sulfate/1 mg Res-NLC with FRAP assay; and by AAPH-induced oxidative injury cell model assay, Res-NLC showed the strong protective effect against the human liver tumor HepG2 cell oxidative stress damage. These results indicated that the antioxidant properties of Res-NLC hold great potential used as an alternative to more toxic synthetic antioxidants as an additive in food, cosmetic and pharmaceutical preparations for the oxidative diseases treatment.

  7. Monte Carlo simulation of non-linear free radical polymerization using a percolation kinetic gelation model (I): free radical homo polymerization

    International Nuclear Information System (INIS)

    Ghiass, M.; Dabir, B.; Nikazar, M.; Rey, A.D.; Mirzadeh, H.

    2001-01-01

    A kinetic gelation model that incorporates the kinetics of free radical homo polymerization is implemented to determine the effects of kinetics on polymerization statistics and microstructures. The simulation is performed on a simple cubic lattice that has 100 sites in each direction. A new algorithm for random selecting of the next step in a self-avoiding random walk and very efficient mechanisms of mobility of components are introduced to improve the generality of the predictions by removing commonly accruing deficiencies due to early trapping of radicals. A first order kinetics is considered for decomposition of initiator that enables us to consider the effect of temperature on polymerization reaction. Better understanding of microstructural evolution during polymerization and providing a framework to produce a realistic system of highly packed random chains within polymer network are among the benefits of model

  8. High density dispersion fuel

    International Nuclear Information System (INIS)

    Hofman, G.L.

    1996-01-01

    A fuel development campaign that results in an aluminum plate-type fuel of unlimited LEU burnup capability with an uranium loading of 9 grams per cm 3 of meat should be considered an unqualified success. The current worldwide approved and accepted highest loading is 4.8 g cm -3 with U 3 Si 2 as fuel. High-density uranium compounds offer no real density advantage over U 3 Si 2 and have less desirable fabrication and performance characteristics as well. Of the higher-density compounds, U 3 Si has approximately a 30% higher uranium density but the density of the U 6 X compounds would yield the factor 1.5 needed to achieve 9 g cm -3 uranium loading. Unfortunately, irradiation tests proved these peritectic compounds have poor swelling behavior. It is for this reason that the authors are turning to uranium alloys. The reason pure uranium was not seriously considered as a dispersion fuel is mainly due to its high rate of growth and swelling at low temperatures. This problem was solved at least for relatively low burnup application in non-dispersion fuel elements with small additions of Si, Fe, and Al. This so called adjusted uranium has nearly the same density as pure α-uranium and it seems prudent to reconsider this alloy as a dispersant. Further modifications of uranium metal to achieve higher burnup swelling stability involve stabilization of the cubic γ phase at low temperatures where normally α phase exists. Several low neutron capture cross section elements such as Zr, Nb, Ti and Mo accomplish this in various degrees. The challenge is to produce a suitable form of fuel powder and develop a plate fabrication procedure, as well as obtain high burnup capability through irradiation testing

  9. Doxorubicin hepatotoxicity and hepatic free radical metabolism in rats

    International Nuclear Information System (INIS)

    Kalender, Yusuf; Yel, Mustafa; Kalender, Suna

    2005-01-01

    Doxorubicin (DXR) is an anthracycline antibiotic, broady used in tumor therapy. In the present study we investigated whether vitamin E and catechin can reduce the toxic effects of doxorubicin. Vitamin E (200 IU/kg/week), catechin (200 mg/kg/week), doxorubicin (5 mg/kg/week), doxorubicin + vitamin E (200 IU/kg/week), doxorubicin + catechin (200 mg/kg/week) combinations were given to rats weighing 210-230 g (n = 6/group). Changes in major enzymes participating in free radical metabolism superoxide dismutase (Cu,Zn-SOD), glutathione peroxidase (GSHPx), catalase (CAT) and malondialdehyde (MDA) were evaluated in the livers of all animals. Superoxide dismutase and catalase activity increased in the doxorubicin-treated group compared to control (P 0.05). Electron microscopic studies supported biochemical findings. We conclude that vitamin E and catechin significantly reduce doxorubicin-induced hepatotoxicity in rats

  10. Photodissociation dynamics and spectroscopy of free radical combustion intermediates

    Energy Technology Data Exchange (ETDEWEB)

    Osborn, David Lewis [Univ. of California, Berkeley, CA (United States)

    1996-12-01

    The photodissociation spectroscopy and dynamics of free radicals is studied by the technique of fast beam photofragment translational spectroscopy. Photodetachment of internally cold, mass-selected negative ions produces a clean source of radicals, which are subsequently dissociated and detected. The photofragment yield as a function of photon energy is obtained, mapping out the dissociative and predissociative electronic states of the radical. In addition, the photodissociation dynamics, product branching ratios, and bond energies are probed at fixed photon energies by measuring the translational energy, P(ET), and angular distribution of the recoiling fragments using a time- and position-sensitive detector. Ab initio calculations are combined with dynamical and statistical models to interpret the observed data. The photodissociation of three prototypical hydrocarbon combustion intermediates forms the core of this work.

  11. Infrared Absorption Spectroscopy and Chemical Kinetics of Free Radicals

    Energy Technology Data Exchange (ETDEWEB)

    Curl, Robert F; Glass, Graham

    2004-11-01

    This research was directed at the detection, monitoring, and study of the chemical kinetic behavior by infrared absorption spectroscopy of small free radical species thought to be important intermediates in combustion. Work on the reaction of OH with acetaldehyde has been completed and published and work on the reaction of O({sup 1}D) with CH{sub 4} has been completed and submitted for publication. In the course of our investigation of branching ratios of the reactions of O({sup 1}D) with acetaldehyde and methane, we discovered that hot atom chemistry effects are not negligible at the gas pressures (13 Torr) initially used. Branching ratios of the reaction of O({sup 1}D) with CH{sub 4} have been measured at a tenfold higher He flow and fivefold higher pressure.

  12. Photodissociation spectroscopy and dynamics of free radicals, clusters, and ions

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Hyeon [Univ. of California, Berkeley, CA (United States)

    1999-12-01

    The photodissociation spectroscopy and dynamics of free radicals and ions is studied to characterize the dissociative electronic states in these species. To accomplish this, a special method of radical production, based on the photodetachment of the corresponding negative ion, has been combined with the technique of fast beam photofragment translational spectroscopy. The photofragment yield as a function of photon energy is obtained, mapping out the dissociative and predissociative electronic states. Branching ratios to various product channels, the translational energy distributions of the fragments, and bond dissociation energies are then determined at selected photon energies. The detailed picture of photodissociation dynamics is provided with the aid of ab initio calculations and a statistical model to interpret the observed data. Important reaction intermediates in combustion reactions have been studied: CCO, C2H5O, and linear Cn (n = 4--6).

  13. Molecular Mechanisms behind Free Radical Scavengers Function against Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Fereshteh Ahmadinejad

    2017-07-01

    Full Text Available Accumulating evidence shows that oxidative stress is involved in a wide variety of human diseases: rheumatoid arthritis, Alzheimer’s disease, Parkinson’s disease, cancers, etc. Here, we discuss the significance of oxidative conditions in different disease, with the focus on neurodegenerative disease including Parkinson’s disease, which is mainly caused by oxidative stress. Reactive oxygen and nitrogen species (ROS and RNS, respectively, collectively known as RONS, are produced by cellular enzymes such as myeloperoxidase, NADPH-oxidase (nicotinamide adenine dinucleotide phosphate-oxidase and nitric oxide synthase (NOS. Natural antioxidant systems are categorized into enzymatic and non-enzymatic antioxidant groups. The former includes a number of enzymes such as catalase and glutathione peroxidase, while the latter contains a number of antioxidants acquired from dietary sources including vitamin C, carotenoids, flavonoids and polyphenols. There are also scavengers used for therapeutic purposes, such as 3,4-dihydroxyphenylalanine (L-DOPA used routinely in the treatment of Parkinson’s disease (not as a free radical scavenger, and 3-methyl-1-phenyl-2-pyrazolin-5-one (Edaravone that acts as a free radical detoxifier frequently used in acute ischemic stroke. The cell surviving properties of L-DOPA and Edaravone against oxidative stress conditions rely on the alteration of a number of stress proteins such as Annexin A1, Peroxiredoxin-6 and PARK7/DJ-1 (Parkinson disease protein 7, also known as Protein deglycase DJ-1. Although they share the targets in reversing the cytotoxic effects of H2O2, they seem to have distinct mechanism of function. Exposure to L-DOPA may result in hypoxia condition and further induction of ORP150 (150-kDa oxygen-regulated protein with its concomitant cytoprotective effects but Edaravone seems to protect cells via direct induction of Peroxiredoxin-2 and inhibition of apoptosis.

  14. Examining the free radical bonding mechanism of benzoquinone– and hydroquinone–methanol passivation of silicon surfaces

    International Nuclear Information System (INIS)

    Kotulak, Nicole A.; Chen, Meixi; Schreiber, Nikolas; Jones, Kevin; Opila, Robert L.

    2015-01-01

    Highlights: • Photons are required for high levels of c-Si passivation by both BQ/ME and HQ/ME solutions. • Protons are required for high levels of c-Si passivation by both BQ/ME and HQ/ME solutions. • The free radical QH· is the likely passivating species for c-Si surfaces from BQ/ME and HQ/ME solutions. - Abstract: The surface passivation of p-benzoquinone (BQ) and hydroquinone (HQ) when dissolved in methanol (ME) has been examined through effective lifetime testing of crystalline silicon (c-Si) wafers treated with the aforementioned solutions. Changes in the availability of both photons and protons in the solutions were demonstrated to affect the level of passivation achieved. The requirement of both excess protons and ambient light exposure to maintain high effective lifetimes supports the presence of a free radical species that drives the surface passivation. Surface analysis suggests a 1:1 ratio of HQ-like bonds to methoxy bonds on the c-Si surface after treatment with a BQ/ME solution.

  15. Standard Gibbs free energies of reactions of ozone with free radicals in aqueous solution: quantum-chemical calculations.

    Science.gov (United States)

    Naumov, Sergej; von Sonntag, Clemens

    2011-11-01

    Free radicals are common intermediates in the chemistry of ozone in aqueous solution. Their reactions with ozone have been probed by calculating the standard Gibbs free energies of such reactions using density functional theory (Jaguar 7.6 program). O(2) reacts fast and irreversibly only with simple carbon-centered radicals. In contrast, ozone also reacts irreversibly with conjugated carbon-centered radicals such as bisallylic (hydroxycylohexadienyl) radicals, with conjugated carbon/oxygen-centered radicals such as phenoxyl radicals, and even with nitrogen- oxygen-, sulfur-, and halogen-centered radicals. In these reactions, further ozone-reactive radicals are generated. Chain reactions may destroy ozone without giving rise to products other than O(2). This may be of importance when ozonation is used in pollution control, and reactions of free radicals with ozone have to be taken into account in modeling such processes.

  16. Neem leaf extract as potential modifier of free radical interaction with RBC membrane

    International Nuclear Information System (INIS)

    Patil, Shilpa M.; Kulkarni, Satish G.; Rane, Charusheela

    2004-01-01

    Full text: Neem tree (Azadirachta indica) is well known as village pharmacy due to its multifaceted medicinal action in curing countless health problems. The leaf extract of Neem is known to purify blood by removing toxins and neutralizing free radicals. Using gamma irradiation as free radical generation process the efficacy of neem leaf extract in combating free radical attack on RBC membrane has been explored. The results narrating role of concentration and dose dependency in this radio modulation will be discussed

  17. Studies on free radical scavenging activity in Chinese seaweeds part I. Screening results

    Science.gov (United States)

    Yan, Xiao-Jun; Fang, Guo-Ming; Lou, Qing-Xiang

    1999-09-01

    Antioxidants have attracted the attention of researchers due to their beneficial effects as free radical scavengers. Application of a stable free radical named 1, 1-diphenyl-2-picrylhydrazyl(DPPH) to screen the free radical scavenging activity in 27 species of Chinese seaweed showed that 15 of them had significant activity in at least one of the organic solvent extracts. The most interesting seaweed species were Gelidium amansii, Gloiosiphonia capillaris, Polysiphonia urceolata, Sargassum kjellmanianum, Desmarestia viridis, and Rhodomela teres.

  18. Free Radical Scavenging Activity and Anthocyanin Profile of Cabernet Sauvignon Wines from the Balkan Region

    Directory of Open Access Journals (Sweden)

    Blaga Radovanović

    2010-06-01

    Full Text Available The present study is focused on anthocyanin derivatives characterizing the antioxidant activity of Cabernet Sauvignon wines produced from different vineyard regions in the Balkans. These bioactive compounds were quantified with a high performance liquid chromatography (HPLC-diode array detection (DAD method. The antiradical activity was estimated by the ability of the wine to scavenge the stable 2,2`-diphenyl-1-picrylhydrazyl free radical (DPPH·. The results show that the total anthocyanin content varied from 205.88 to 1940.28 mg/L, depending on agroclimatic factors and the enological practices of the corresponding vineyard region. The most prominent antocyanin in all investigated Cabernet Sauvignon wines was malvidin-3-O-monoglucoside, which accounted for 50.57% of total content, followed by its acetyl derivatives, 15.45%, and p-coumaryl derivatives 5.66%. The relationship between the anthocyanin derivatives and free radical scavenging activity is discussed. A high correlation between total anthocyanin content and DPPH· scavenging ability of tested wines was confirmed (r2 = 0.9619. The significant correlations were obtained between antiradical activity and the sum of 3-monoglucoside (r2 = 0.95594, the sum of 3-acetyl-3-glucoside (r2 = 0.9728 and the sum of p-coumaryl-3-glucoside (r2 = 0.8873 of wine samples. It can be concluded that, the anthocyanin composition can be used as biochemical marker for the authenticity of red grape cultivar and their corresponding single-cultivar wine.

  19. Updating the mitochondrial free radical theory of aging: an integrated view, key aspects, and confounding concepts.

    Science.gov (United States)

    Barja, Gustavo

    2013-10-20

    An updated version of the mitochondrial free radical theory of aging (MFRTA) and longevity is reviewed. Key aspects of the theory are emphasized. Another main focus concerns common misconceptions that can mislead investigators from other specialties, even to wrongly discard the theory. Those different issues include (i) the main reactive oxygen species (ROS)-generating site in the respiratory chain in relation to aging and longevity: complex I; (ii) the close vicinity or even contact between that site and the mitochondrial DNA, in relation to the lack of local efficacy of antioxidants and to sub-cellular compartmentation; (iii) the relationship between mitochondrial ROS production and oxygen consumption; (iv) recent criticisms on the MFRTA; (v) the widespread assumption that ROS are simple "by-products" of the mitochondrial respiratory chain; (vi) the unnecessary postulation of "vicious cycle" hypotheses of mitochondrial ROS generation which are not central to the free radical theory of aging; and (vii) the role of DNA repair concerning endogenous versus exogenous damage. After considering the large body of data already available, two general characteristics responsible for the high maintenance degree of long-lived animals emerge: (i) a low generation rate of endogenous damage: and (ii) the possession of tissue macromolecules that are highly resistant to oxidative modification.

  20. Effect of metal complexation to anti-inflammatory over the action against oxidative and free radicals: ketoprofen action; Efeito da complexacao de metais aos antiinflamatorios na acao contra agentes oxidativos e radicais livres: acao do cetoprofeno

    Energy Technology Data Exchange (ETDEWEB)

    Manente, Francine Alessandra; Mello, Lucas Rosolen de Almeida; Vellosa, Jose Carlos Rebuglio [UEPG, Universidade Estadual de Ponta Grossa, Departamento de Analises Clinicas eToxicologicas, Ponta Grossa, PR (Brazil); Khalil, Omar Arafat Kdudsi [IFG, Instituto Federal de Goias, Campus de Formosa, Formosa - GO (Brazil); Carvalho, Claudio Teodoro de [UFGD, Universidade Federal da Grande Dourados, Faculdade de Ciencias Exatas e Tecnologias, Dourados-MS (Brazil); Bannach, Gilbert [UNESP, Universidade Estadual Paulista Julio de Mesquita Filho, Faculdade de Ciencias de Bauru, Bauru, SP (Brazil)

    2011-07-01

    Free radicals are highly reactive species generated in living organisms for the purpose of protection. However, in some circumstances, they are responsible for the occurrence or aggravation of tissue damage. Many anti-inflammatory drugs have a direct effect on free radicals and not radical reactive species, which contributes to its actions against inflammation. Ketoprofen is a nonsteroidal anti-inflammatory agent that generates free radicals by photo irradiation and has an important hemolytic effect with that. The complexation of metals to different drugs has been used as a strategy to improve the pharmacological action of different molecules and reduce their side effects. This paper presents the results of ketoprofen and their metallic complexes action on erythrocytes and free radicals. It was observed that the cerium enhances the scavenger properties of ketoprofen on free radicals, while copper enhances its action over non-radical oxidants. Copper also reduced the hemolytic effect presented by ketoprofen meanwhile its cerium derivative maintained it. (author)

  1. Free Radical Oxidation in Rat Myocardium after Maximum Permissible Hepatic Resection.

    Science.gov (United States)

    Ermolaev, P A; Khramykh, T P; Barskaya, L O

    2016-03-01

    Free radical oxidation in rat myocardial homogenate was studied by chemiluminescent assay during the early terms after maximum permissible liver resection. During this period, activation of free radical oxidation was biphasic. The critical terms characterized by dramatic intensification of free radical oxidation in the myocardium are the first hour and the first day after surgery. The period from 3 to 12 h after surgery, in which the indices of chemiluminescence decrease, can be tentatively termed as the period of "putative wellbeing". Normalization of the free radical oxidation processes in the myocardium occurred by day 7 after surgery.

  2. EPR study of N+-ion-induced free radical formation in antibiotic-producers

    International Nuclear Information System (INIS)

    Xie Liqing; Zhang Yinfen; Chen Ruyi; Gao Juncheng; Zhang Peiling; Ying Hengfeng.

    1995-01-01

    Under the room temperature, electron paramagnetic resonance (EPR) spectrometer was used to study free radical formation in antibiotic-producers in order to investigate antibiotic-producer mutagenic breeding, which were induced by N + ion implanting into antibiotic-producers (e.g., Streptomyces ribosidificus, Streptomyces kanamyceticus and the phage-resistant culture of Streptomyces kanamyceticus). The results show that a lot of free radicals can be induced by N + ion implanting into antibiotic-producers, and the yields of the free radicals increase with implanting dose. The death rate of antibiotic-producers rises due to the increase of N + -ion-induced free radical yields. (author)

  3. Role of Free Radicals, Oxidative Stress and Xenobiotics in Carcinogenesis by Environmental Pollutants

    Directory of Open Access Journals (Sweden)

    Dibyajyoti Saha

    2014-09-01

    Full Text Available Carcinogenesis by many small molecular weight chemicals involves either a direct action of the chemical on cellular DNA or metabolism of the parent chemical to an active or ultimate form, which can than react with cellular DNA to produce a permanent chemical change in a DNA structure. A free radical is an atom or molecule that has one or more unpaired electron(s. These are highly reactive species capable of wide spread, indiscriminate oxidation and per oxidation of proteins, lipids and DNA which can lead to significant cellular damage and even tissue and/or organ failure. . Oxidative stress is a leading cause to damage cells by oxidation. The rate at which oxidative damage is induced (input and the rate at which it is efficiently repaired and removed (output. Xenobiotics are a compound that is foreign to the body. Xenobiotics can produce a variety of biological effects, including pharmacologic responses, toxicity, genes, immunologic reactions and cancer. Oxidative stress is a leading cause to damage cells by oxidation. The rate at which oxidative damage is induced (input and the rate at which it is efficiently repaired and removed (output. This communication highlights the role of carcinogens as environmental pollutants with the possible mechanism of free radicals, oxidative stress and xenobiotics.

  4. Near-Infrared Free-Radical and Free-Radical-Promoted Cationic Photopolymerizations by In-Source Lighting Using Upconverting Glass.

    Science.gov (United States)

    Kocaarslan, Azra; Tabanli, Sevcan; Eryurek, Gonul; Yagci, Yusuf

    2017-11-13

    A method is presented for the initiation of free-radical and free-radical-promoted cationic photopolymerizations by in-source lighting in the near-infrared (NIR) region using upconverting glass (UCG). This approach utilizes laser irradiation of UCG at 975 nm in the presence of fluorescein (FL) and pentamethyldiethylene triamine (PMDETA). FL excited by light emitted from the UCG undergoes electron-transfer reactions with PMDETA to form free radicals capable of initiating polymerization of methyl methacrylate. To execute the corresponding free-radical-promoted cationic polymerization of cyclohexene oxide, isobutyl vinyl ether, and N-vinyl carbazole, it was necessary to use FL, dimethyl aniline (DMA), and diphenyliodonium hexafluorophosphate as sensitizer, coinitiator, and oxidant, respectively. Iodonium ions promptly oxidize DMA radicals formed to the corresponding cations. Thus, cationic polymerization with efficiency comparable to the conventional irradiation source was achieved. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Investigation of free-radical processes in low temperature radiolysis of copolymers of ethylene with styrene

    International Nuclear Information System (INIS)

    Mal'tseva, A.P.; Golikov, V.P.; Leshchenko, S.S.; Karpov, V.L.; Muromtsev, V.I.

    1977-01-01

    Free radical processes during γ-radiolysis of statistical ethylene-styrene copolimers (ESC) have been investigated. The presence of styrene links in the ESC has been shown to reduce both radical yields and their reaction ability as compared with low density polyethylene irradiated under the same conditions. The character of radical processes in ESC sighificantly depends both on styrene concentration in them and on the dose absorbed. The most pronounced decrease in radical yield is found in the copolymer having 5 mol % styrene. This effect seems to be caused by the accumulation in the irradiated copolymer of products which are capable of more effective dissipation of absorbed energy than only styrene links alone

  6. Evolution of material properties during free radical photopolymerization

    Science.gov (United States)

    Wu, Jiangtao; Zhao, Zeang; Hamel, Craig M.; Mu, Xiaoming; Kuang, Xiao; Guo, Zaoyang; Qi, H. Jerry

    2018-03-01

    Photopolymerization is a widely used polymerization method in many engineering applications such as coating, dental restoration, and 3D printing. It is a complex chemical and physical process, through which a liquid monomer solution is rapidly converted to a solid polymer. In the most common free-radical photopolymerization process, the photoinitiator in the solution is exposed to light and decomposes into active radicals, which attach to monomers to start the polymerization reaction. The activated monomers then attack Cdbnd C double bonds of unsaturated monomers, which leads to the growth of polymer chains. With increases in the polymer chain length and the average molecular weight, polymer chains start to connect and form a network structure, and the liquid polymer solution becomes a dense solid. During this process, the material properties of the cured polymer change dramatically. In this paper, experiments and theoretical modeling are used to investigate the free-radical photopolymerization reaction kinetics, material property evolution and mechanics during the photopolymerization process. The model employs the first order chemical reaction rate equations to calculate the variation of the species concentrations. The degree of monomer conversion is used as an internal variable that dictates the mechanical properties of the cured polymer at different curing states, including volume shrinkage, glass transition temperature, and nonlinear viscoelastic properties. To capture the nonlinear behavior of the cured polymer under low temperature and finite deformation, a multibranch nonlinear viscoelastic model is developed. A phase evolution model is used to describe the mechanics of the coupling between the crosslink network evolution and mechanical loading during the curing process. The comparison of the model and the experimental results indicates that the model can capture property changes during curing. The model is further applied to investigate the internal stress

  7. "Living" free radical photopolymerization initiated from surface-grafted iniferter monolayers

    NARCIS (Netherlands)

    de Boer, B.; Simon, H.K.; Werts, M.P L; van der Vegte, E.W.; Hadziioannou, G

    2000-01-01

    A method for chemically modifying a surface with grafted monolayers of initiator groups, which can be used for a "living" free radical photopolymerization, is described. By using "living" free radical polymerizations, we were able to control the length of the grafted polymer chains and therefore the

  8. Investigating free radical generation in HepG2 cells using immuno-spin trapping.

    Science.gov (United States)

    Horinouchi, Yuya; Summers, Fiona A; Ehrenshaft, Marilyn; Kawazoe, Kazuyoshi; Tsuchiya, Koichiro; Tamaki, Toshiaki; Mason, Ronald P

    2014-10-01

    Oxidative stress can induce the generation of free radicals, which are believed to play an important role in both physiological and pathological processes and a number of diseases such as cancer. Therefore, it is important to identify chemicals which are capable of inducing oxidative stress. In this study, we evaluated the ability of four environmental chemicals, aniline, nitrosobenzene (NB), N,N-dimethylaniline (DMA) and N,N-dimethyl-4-nitrosoaniline (DMNA), to induce free radicals and cellular damage in the hepatoma cell line HepG2. Cytotoxicity was assessed using lactate dehydrogenase (LDH) assays and morphological changes were observed using phase contrast microscopy. Free radicals were detected by immuno-spin trapping (IST) in in-cell western experiments or in confocal microscopy experiments to determine the subcellular localization of free radical generation. DMNA induced free radical generation, LDH release and morphological changes in HepG2 cells whereas aniline, NB and DMA did not. Confocal microscopy showed that DMNA induced free radical generation mainly in the cytosol. Preincubation of HepG2 cells with N-acetylcysteine and 2,2'-dipyridyl significantly prevented free radical generation upon subsequent incubation with DMNA, whereas preincubation with apocynin and dimethyl sulfoxide did not. These results suggest that DMNA induces oxidative stress and that reactive oxygen species, metals and free radical generation play a critical role in DMNA-induced cytotoxicity. Copyright © 2014. Published by Elsevier Inc.

  9. “Living” Free Radical Photopolymerization Initiated from Surface-Grafted Iniferter Monolayers

    NARCIS (Netherlands)

    Boer, B. de; Simon, H.K.; Werts, M.P.L.; Vegte, E.W. van der; Hadziioannou, G.

    2000-01-01

    A method for chemically modifying a surface with grafted monolayers of initiator groups, which can be used for a “living” free radical photopolymerization, is described. By using “living” free radical polymerizations, we were able to control the length of the grafted polymer chains and therefore the

  10. Adriamycin and derivatives interaction with the mitochondrial membrane: O2 consumption and free radicals formation

    NARCIS (Netherlands)

    Pollakis, G.; Goormaghtigh, E.; Delmelle, M.; Lion, Y.; Ruysschaert, J. M.

    1984-01-01

    Adriamycin induces the formation of semiquinone free radicals, O(2) and OH. species, in beef heart intact mitochondria, submitochondrial particles and complex I-III containing proteoliposomes. Free radicals were detected by the use of Electron Spin Resonance (ESR) spectroscopy with the spin trapping

  11. Oxygen free radical altered immunoglobin G in the etiopathogenesis of rheumatoid arthritis

    NARCIS (Netherlands)

    H.A. Kleinveld (Henk)

    1990-01-01

    textabstractThe particular association of RA with anti-lgG antibodies suggests an important role of lgG in the etiology and pathology of RA. One of the suggested mechanisms by which lgG could be altered is exposure to oxygen free radicals. During inflammation large amounts of oxygen free radicals

  12. Comparative investigation of the free radical scavenging potential and anticancer property of Diospyros blancoi (Ebenaceae

    Directory of Open Access Journals (Sweden)

    Muhammad Ali Khan

    2016-05-01

    Conclusions: Our results indicate that Diospyros blancoi stem bark had the significant highest antioxidant and free radical scavenging properties as well as moderate anticancer activity. Hence, we assume that the anticancer activity of this plant can be, at least in part, attributed to its content in phenolic compounds as well as its significant free radical scavenging properties.

  13. Free radicals generated by radiolysis of aqueous solutions

    International Nuclear Information System (INIS)

    Schwarz, H.A.

    1981-01-01

    The free radicals produced in the radiolysis of aqueous solutions span the range of redox potentials from -2.9 to +2.65 volts. The identity and nature of these radicals were discussed. Most of the discussion was results obtained with low LET radiation sources ( 60 Co gamma radiation or electron accelerators). Water radiolysis provides the synthesis of many radicals and radical ions in aqueous solution. The primary radicals, e/sub aq/ - H, OH, are well characterized. The radical population can be made to be 90% pure OH (or O - ) if N 2 O solutions are irradiated, the remaining 10% being H atoms. 55% of the radicals can be converted to H atoms in acid solution or in neutral phosphate solutions(e/sub aq/ - reacts with H 2 PO 4- to produce H). The remaining 45% (OH radicals) are difficult to convert to H by reaction with H 2 , due to the slow rate of the reaction. About 100 atmospheres of H 2 are required to do the conversion in less than 10 - 6 sec. 3 figures, 3 tables. (DP)

  14. Modulation of oxidative damage by nitroxide free radicals.

    Science.gov (United States)

    Dragutan, Ileana; Mehlhorn, Rolf J

    2007-03-01

    Piperidine nitroxides like 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) are persistent free radicals in non-acidic aqueous solutions and organic solvents that may have value as therapeutic agents in medicine. In biological environments, they undergo mostly reduction to stable hydroxylamines but can also undergo oxidation to reactive oxoammonium compounds. Reactions of the oxoammonium derivatives could have adverse consequences including chemical modification of vital macromolecules and deleterious effects on cell signaling. An examination of their reactivity in aqueous solution has shown that oxoammonium compounds can oxidize almost any organic as well as many inorganic molecules found in biological systems. Many of these reactions appear to be one-electron transfers that reduce the oxoammonium to the corresponding nitroxide species, in contrast to a prevalence of two-electron reductions of oxoammonium in organic solvents. Amino acids, alcohols, aldehydes, phospholipids, hydrogen peroxide, other nitroxides, hydroxylamines, phenols and certain transition metal ions and their complexes are among reductants of oxoammonium, causing conversion of this species to the paramagnetic nitroxide. On the other hand, thiols and oxoammonium yield products that cannot be detected by ESR even under conditions that would oxidize hydroxylamines to nitroxides. These products may include hindered secondary amines, sulfoxamides and sulfonamides. Thiol oxidation products other than disulfides cannot be restored to thiols by common enzymatic reduction pathways. Such products may also play a role in cell signaling events related to oxidative stress. Adverse consequences of the reactions of oxoammonium compounds may partially offset the putative beneficial effects of nitroxides in some therapeutic settings.

  15. In vitro free radical scavenging activity of platinum nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Aki; Kajita, Masashi; Kim, Juewon; Kanayama, Atsuhiro; Miyamoto, Yusei [Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Bioscience Building 402, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562 (Japan); Takahashi, Kyoko; Mashino, Tadahiko, E-mail: yusei74@k.u-tokyo.ac.j [Department of Pharmaceutical Sciences, Faculty of Pharmacy, Keio University, 1-5-30 Shibakoen, Minato, Tokyo 105-8512 (Japan)

    2009-11-11

    A polyacrylic acid (PAA)-protected platinum nanoparticle species (PAA-Pt) was prepared by alcohol reduction of hexachloroplatinate. The PAA-Pt nanoparticles were well dispersed and homogeneous in size with an average diameter of 2.0 {+-} 0.4 nm (n = 200). We used electron spin resonance to quantify the residual peroxyl radical AOO. generated from 2,2-azobis (2-aminopropane) dihydrochloride (AAPH) by thermal decomposition in the presence of O{sub 2} and a spectrophotometric method to quantify the residual 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. PAA-Pt scavenged these two radicals in a dose-dependent manner. Platinum was the functional component. PAA-Pt reduced the rate of oxygen consumption required for linoleic acid peroxidation initiated by AOO. generated from AAPH, indicating inhibition of the propagation of linolate peroxidation. A thiobarbituric acid test also revealed dose-dependent inhibition of the linolate peroxidation by PAA-Pt. Fifty micromolar platinum, as PAA-Pt, completely quenched 250 {mu}M DPPH radical for 5 min. Even when twice diluted in half, the PAA-Pt still quenched 100% of the 250 {mu}M DPPH radical. The scavenging activity of PAA-Pt is durable. These observations suggest that PAA-Pt is an efficient scavenger of free radicals.

  16. A Derivative Method with Free Radical Oxidation to Predict Resveratrol Metabolites by Tandem Mass Spectrometry.

    Science.gov (United States)

    Liu, Wangta; Shiue, Yow-Ling; Lin, Yi-Reng; Lin, Hugo You-Hsien; Liang, Shih-Shin

    2015-10-01

    In this study, we demonstrated an oxidative method with free radical to generate 3,5,4'-trihydroxy- trans -stilbene ( trans -resveratrol) metabolites and detect sequentially by an autosampler coupling with liquid chromatography electrospray ionization tandem mass spectrometer (LC-ESI-MS/MS). In this oxidative method, the free radical initiator, ammonium persulfate (APS), was placed in a sample bottle containing resveratrol to produce oxidative derivatives, and the reaction progress was tracked by autosampler sequencing. Resveratrol, a natural product with purported cancer preventative qualities, produces metabolites including dihydroresveratrol, 3,4'-dihydroxy- trans -stilbene, lunularin, resveratrol monosulfate, and dihydroresveratrol monosulfate by free radical oxidation. Using APS free radical, the concentrations of resveratrol derivatives differ as a function of time. Besides simple, convenient and time- and labor saving, the advantages of free radical oxidative method of its in situ generation of oxidative derivatives followed by LC-ESI-MS/MS can be utilized to evaluate different metabolites in various conditions.

  17. Study Free Radical Of Irradiated Pulasari (Alexyia reinwadrtii BI) By Using Electron Spin Resonance (ESR)

    International Nuclear Information System (INIS)

    Erizal; Chosdu, Rahayu

    2000-01-01

    In the effort to develop the application of gamma irradiation for medicinal plant preservation especially for seeds i.e. pulasari (Alyxia reinwardtii Bi), the characteristic of free radical of irradiated pulasari (water content 4-6%) at doses of 10; 20; 30 kGy after storage time ranged 0-70 days were studied by using electron spin resonance. It was found that with increasing irradiation dose, the yield of free radicals formation increase. The yield of free radical of pulasari powder more lower than in a chips state. With increasing storage time up 5 days, the yield of free radical decrease up to 60-70 %. At storage time up to 70 days, the free radical remained ranged 10-20%, relatively

  18. Novel Water Soluble Chitosan Derivatives with 1,2,3-Triazolium and Their Free Radical-Scavenging Activity.

    Science.gov (United States)

    Li, Qing; Sun, Xueqi; Gu, Guodong; Guo, Zhanyong

    2018-03-28

    Chitosan is an abundant and renewable polysaccharide, which exhibits attractive bioactivities and natural properties. Improvement such as chemical modification of chitosan is often performed for its potential of providing high bioactivity and good water solubility. A new class of chitosan derivatives possessing 1,2,3-triazolium charged units by associating "click reaction" with efficient 1,2,3-triazole quaternization were designed and synthesized. Their free radical-scavenging activity against three free radicals was tested. The inhibitory property and water solubility of the synthesized chitosan derivatives exhibited a remarkable improvement over chitosan. It is hypothesized that triazole or triazolium groups enable the synthesized chitosan to possess obviously better radical-scavenging activity. Moreover, the scavenging activity against superoxide radical of chitosan derivatives with triazolium (IC 50 radical-scavenging assay, the same pattern were observed, which should be related to the triazolium grafted at the periphery of molecular chains.

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

    International Nuclear Information System (INIS)

    Goossens, Lieven

    2011-01-01

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

  20. Photodissociation of Small Molecules and Photoionization of Free Radicals Using the VUV Velocity-Map Imaging Photoion and Photoelectron Method

    Science.gov (United States)

    Gao, Hong

    The tunable vacuum ultraviolet (VUV) laser generated through the two-photon resonance-enhanced four-wave mixing scheme is combined with the newly developed time-slice velocity map imaging photoion method to study the photodissociation of small molecules in the VUV region, and with the velocity map imaging photoelectron method to study the photoionization of free radicals. The photodissociation dynamics of NO in the energy region around 13.5 eV has been investigated. Branching ratios of the three lowest dissociation channels of 12C 16O that produce C(3P) + O(3P), C( 1D) + O(3P) and C(3P) + O(1D) are measured for the first time in the VUV region from 102,500 cm-1 to 110,500 cm-1, valuable information of the dissociation dynamics for this prototype system has been deduced. We demonstrated an experiment that has two independently tunable VUV lasers and a time-slice velocity map imaging setup, this provides us a global way to perform systematic state-selected photodissociation of small molecules via state-selected detection of the atomic products in the VUV region. The velocity map imaging photoelectron method was successfully used to obtain the photoelectron spectrum of the propargyl radical (C3H3) via a single VUV photoionization process. The propargyl radical is generated by the 193 nm laser photodissociation of the precursor C3H3Cl. This is the first time that the velocity map imaging photoelectron method is used to get the photoelectron spectra of free radicals, indicating that it is a powerful technique for studying the photoionization of free radicals which are always hard to be produced with high enough number densities for spectroscopic studies. This dissertation is mainly based on the following peer-reviewed journal articles: 1. Hong Gao, Yang Pan, Lei Yang, Jingang Zhou, C. Y. Ng and William M. Jackson. "Time-slice velocity-map ion imaging studies of the Photodissociation of NO in the vacuum ultraviolet region", the Journal of Chemical Physics, 136, 134302

  1. Review Article: Dyslipidaemia, Lipid Oxidation, And Free Radicals In ...

    African Journals Online (AJOL)

    Diabetes mellitus is frequently associated with dyslipidaemia evidenced by high prevalence rate that range from 16%-40%, and chronically elevated level of plasma lipids, low-density lipoprotein in particular, leads to modification of structures, importantly through oxidative processes. Renal tissue particularly in diabetes ...

  2. Star-shaped Polymers through Simple Wavelength-Selective Free-Radical Photopolymerization.

    Science.gov (United States)

    Eibel, Anna; Fast, David E; Sattelkow, Jürgen; Zalibera, Michal; Wang, Jieping; Huber, Alex; Müller, Georgina; Neshchadin, Dmytro; Dietliker, Kurt; Plank, Harald; Grützmacher, Hansjörg; Gescheidt, Georg

    2017-11-06

    Star-shaped polymers represent highly desired materials in nanotechnology and life sciences, including biomedical applications (e.g., diagnostic imaging, tissue engineering, and targeted drug delivery). Herein, we report a straightforward synthesis of wavelength-selective multifunctional photoinitiators (PIs) that contain a bisacylphosphane oxide (BAPO) group and an α-hydroxy ketone moiety within one molecule. By using three different wavelengths, these photoactive groups can be selectively addressed and activated, thereby allowing the synthesis of ABC-type miktoarm star polymers through a simple, highly selective, and robust free-radical polymerization method. The photochemistry of these new initiators and the feasibility of this concept were investigated in unprecedented detail by using various spectroscopic techniques. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Surface modification of carbon nanotubes via combination of mussel inspired chemistry and chain transfer free radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Qing; Tian, Jianwen; Liu, Meiying; Zeng, Guangjian; Huang, Qiang [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang, 330031 (China); Wang, Ke; Zhang, Qingsong [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing, 100084 (China); Deng, Fengjie, E-mail: fengjiedeng@aliyun.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang, 330031 (China); Zhang, Xiaoyong, E-mail: xiaoyongzhang1980@gmail.com [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang, 330031 (China); Wei, Yen, E-mail: weiyen@tsinghua.edu.cn [Department of Chemistry and the Tsinghua Center for Frontier Polymer Research, Tsinghua University, Beijing, 100084 (China)

    2015-08-15

    Graphical abstract: A novel strategy combination of mussel inspired chemistry and chain transfer free radical polymerization has been developed for surface modification of carbon nanotubes with polymers for the first time. - Highlights: • Surface modification of CNTs via mussel inspired chemistry. • Preparation of aminated polymers through free radical polymerization. • Functionalized CNTs with aminated polymers via Michael addition reaction. • Highly dispersed CNTs in organic and aqueous solution. - Abstract: In this work, a novel strategy for surface modification of carbon nanotubes (CNTs) was developed via combination of mussel inspired chemistry and chain transfer free radical polymerization. First, pristine CNTs were functionalized with polydopamine (PDA), which is formed via self-polymerization of dopamine in alkaline conditions. These PDA functionalized CNTs can be further reacted with amino-terminated polymers (named as PDMC), which was synthesized through chain transfer free radical polymerization using cysteamine hydrochloride as chain transfer agent and methacryloxyethyltrimethyl ammonium chloride as the monomer. PDMC perfectly conjugated with CNT-PDA was ascertained by a series of characterization techniques including transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The dispersibility of obtained CNT nanocomposites (named as CNT-PDA-PDMC) was further examined. Results showed that the dispersibility of CNT-PDA-PDMC in aqueous and organic solutions was obviously enhanced. Apart from PDMC, many other amino-terminated polymers can also be used to functionalization of CNTs via similar strategy. Therefore, the method described in this work should be a general strategy for fabrication various polymer nanocomposites.

  4. Magnetic Levitation To Characterize the Kinetics of Free-Radical Polymerization.

    Science.gov (United States)

    Ge, Shencheng; Semenov, Sergey N; Nagarkar, Amit A; Milette, Jonathan; Christodouleas, Dionysios C; Yuan, Li; Whitesides, George M

    2017-12-27

    This work describes the development of magnetic levitation (MagLev) to characterize the kinetics of free-radical polymerization of water-insoluble, low-molecular-weight monomers that show a large change in density upon polymerization. Maglev measures density, and certain classes of monomers show a large change in density when monomers covalently join in polymer chains. MagLev characterized both the thermal polymerization of methacrylate-based monomers and the photopolymerization of methyl methacrylate and made it possible to determine the orders of reaction and the Arrhenius activation energy of polymerization. MagLev also made it possible to monitor polymerization in the presence of solids (aramid fibers, and carbon fibers, and glass fibers). MagLev offers a new analytical technique to materials and polymer scientists that complements other methods (even those based on density, such as dilatometry), and will be useful in investigating polymerizations, evaluating inhibition of polymerizations, and studying polymerization in the presence of included solid materials (e.g., for composite materials).

  5. Cellular and Molecular Mechanisms of the Production of Free Radicals during Exercise and Their Function on Skeletal Muscles

    Directory of Open Access Journals (Sweden)

    2017-06-01

    Full Text Available Physical activity is an integral part of human life. Among significant biological changes during physical activity are increase of metabolism and production of free radicals. Free radical can be defined as molecule or molecular fragments containing unpaired electron in the outer orbital, which react with nearby molecules to obtain stability. These highly reactive molecules have various deleterious effects, such as reduced force generation and increased muscle atrophy. There is evidence that ROS produced during exercise has positive adaptation effects. ROS production leads to increased expression of the anti-oxidants. These molecules, by neutralizing free radicals, neutralize the negative effects of ROS. In addition, exercise-induced ROS leads to the expression of PGC-1α  protein, having a significant impact on various aspects of cell metabolism, mitochondrial biogenesis and cellular respiration as well as metabolism of fat and glucose. This paper provides an overview of the evidence to date on the effects of ROS on exercising muscle. These aspects include the sources of ROS, their positive and negative cellular effects,  role of antioxidants, and ROS-dependent adaptations of muscle cells in response to physical exercise

  6. FREE RADICAL SCAVENGING CAPACITY OF PAPAVER SOMNIFERUM L. AND DETERMINATION OF PHARMACOLOGICALLY ACTIVE ALKALOIDS USING CAPILLARY ELECTROPHORESIS

    Directory of Open Access Journals (Sweden)

    Marián Valko

    2012-02-01

    Full Text Available The free radical generation is related to the oxidation process in biological systems as well as in foods. It was found that oxidation is affected by antioxidants that can act as radical scavengers. Objective of the present work was to study the free radical scavenging capacity of opium poppy (Papaver somniferum L. extract by using the DPPH test and to verify the suitability of the micellar electrokinetic capillary chromatography (MEKC technique for analytical assessment and determination of three major poppy alkaloids (thebaine, morphine and papaverine. Because of its generally high separation efficiency, the MEKC is successfully used for analytical evaluation of biologically active substances usually without special claims for sample preparation. The results of DPPH test have shown that poppy contains components capable of terminating free radicals. We have confirmed that nature of the solvent used for the electrophoretic medium in MEKC has a strong influence on the separation efficiency. In our experiments, the most effective solvent was mixture of water to acetonitrile (ratio 4:6.

  7. Extracts and Constituents of Rubus chingii with 1,1-Diphenyl-2-picrylhydrazyl (DPPH Free Radical Scavenging Activity

    Directory of Open Access Journals (Sweden)

    Hsiou-Yu Ding

    2011-06-01

    Full Text Available The 1,1-diphenyl-2-picrylhydrazyl (DPPH free radical scavenging activity of the fruits of Rubus chingii was studied in vitro. Ethanolic extract, ethyl acetate and n-butanol fractions from dried R. chingii fruits revealed strong DPPH free radical scavenging activity with IC50 values of 17.9, 3.4 and 4.0 µg/mL, respectively. The ethyl acetate and n-butanol fractions were further purified by a combination of silica gel chromatography, Lobar RP-8 chromatography, and high-pressure liquid chromatography (HPLC. Nine compounds were isolated, where methyl (3-hydroxy-2-oxo-2,3-dihydroindol-3-yl-acetate (2, vanillic acid (5, kaempferol (7, and tiliroside (9 showed stronger DPPH free radical scavenging activity than that of ascorbic acid (131.8 µM with IC50 values of 45.2, 34.9, 78.5, and 13.7 µM, respectively. In addition, rubusine (1 is a new compound discovered in the present study and methyl (3-hydroxy-2-oxo-2,3-dihydroindol-3-yl-acetate (2, methyl dioxindole-3-acetate (3, and 2-oxo-1,2-dihydroquinoline-4-carboxylic acid (4 were isolated from the fruits for the first time.

  8. Generation of hydrogen free radicals from water for fuels by electric field induction

    International Nuclear Information System (INIS)

    Nong, Guangzai; Chen, Yiyi; Li, Ming; Zhou, Zongwen

    2015-01-01

    Highlights: • Hydrogen free radicals are generated from water splitting. • Hydrogen fuel is generated from water by electric field induction. • Hydrocarbon fuel is generated from CO_2 and water by electric field induction. - Abstract: Water is the most abundant resource for generating hydrogen fuel. In addition to dissociating H"+ and "−OH ions, certain water molecules dissociate to radicals under an electric field are considered. Therefore, an electric field inducing reactor is constructed and operated to generate hydrogen free radicals in this paper. Hydrogen free radicals begin to be generated under a 1.0 V electric field, and increasing the voltage and temperature increases the number of hydrogen free radicals. The production rate of hydrogen free radicals is 0.245 mmol/(L h) at 5.0 V and room temperature. The generated hydrogen free radicals are converted to polymer fuel and hydrogen fuel at production rates of 0.0093 mmol/(L h) and 0.0038 mmol/(L h) respectively, under 5.0 V and 0.25 mA. The results provide a way to generate hydrogen free radicals, which might be used to generate hydrocarbon fuel in industrial manufacture.

  9. High density hydrogen research

    International Nuclear Information System (INIS)

    Hawke, R.S.

    1977-01-01

    The interest in the properties of very dense hydrogen is prompted by its abundance in Saturn and Jupiter and its importance in laser fusion studies. Furthermore, it has been proposed that the metallic form of hydrogen may be a superconductor at relatively high temperatures and/or exist in a metastable phase at ambient pressure. For ten years or more, laboratories have been developing the techniques to study hydrogen in the megabar region (1 megabar = 100 GPa). Three major approaches to study dense hydrogen experimentally have been used, static presses, shockwave compression, and magnetic compression. Static tchniques have crossed the megabar threshold in stiff materials but have not yet been convincingly successful in very compressible hydrogen. Single and double shockwave techniques have improved the precision of the pressure, volume, temperature Equation of State (EOS) of molecular hydrogen (deuterium) up to near 1 Mbar. Multiple shockwave and magnetic techniques have compressed hydrogen to several megabars and densities in the range of the metallic phase. The net result is that hydrogen becomes conducting at a pressure between 2 and 4 megabars. Hence, the possibility of making a significant amount of hydrogen into a metal in a static press remains a formidable challenge. The success of such experiments will hopefully answer the questions about hydrogen's metallic vs. conducting molecular phase, superconductivity, and metastability. 4 figures, 15 references

  10. Effect of radiation sterilization on free radicals content in dry beverages

    International Nuclear Information System (INIS)

    Hidayati, Nur; Sudiro, Sutjipto; Maha, Munsiah

    1998-01-01

    This study was done to determine free radicals content in several dry beverages, namely instant coffee, milk powder, cane sugar, nutrisari, tea, and cacao powder after radiation-sterilization at 25 kGy and stored at room (24 o C) and freezing (-13 o C) temperatures. Each sample was vacuum-packed in Al foil laminate pouches, then irradiated at 25 kGy in dry ice temperature. Free radicals contents in some samples after being dissolved or soaked in hot water (73 o C) then freeze-dried were also measured. The free radicals content was measured using Electron Spin Resonance (ESR) Spectroscopy and expressed in spectrum area/g in arbitrary unit. The results showed that free radicals content increased after irradiation, but it decreased immediately after storage especially at room temperature. After about 5 months storage either at room or freezing temperature, free radicals contents of irradiated coffee, milk, powder and cacao powder were similar to those of the unirradiated control, while in tea sample stored at freezing temperature, the free radicals content was still a little bit higher than that stored at room temperature which was already similar to the control. Free radicals content of irradiated sugar as well as nutrisari was higher than the other samples, and the radicals were relatively stable either at room or freezing temperatures. However, after dissolving or soaking the samples in water, the ESR spectra or free radicals contents of the irradiated samples were found to be identical to the control. This indicates that free radicals formed by irradiation in the samples disappear because termination. (authors)

  11. High Power Density Motors

    Science.gov (United States)

    Kascak, Daniel J.

    2004-01-01

    With the growing concerns of global warming, the need for pollution-free vehicles is ever increasing. Pollution-free flight is one of NASA's goals for the 21" Century. , One method of approaching that goal is hydrogen-fueled aircraft that use fuel cells or turbo- generators to develop electric power that can drive electric motors that turn the aircraft's propulsive fans or propellers. Hydrogen fuel would likely be carried as a liquid, stored in tanks at its boiling point of 20.5 K (-422.5 F). Conventional electric motors, however, are far too heavy (for a given horsepower) to use on aircraft. Fortunately the liquid hydrogen fuel can provide essentially free refrigeration that can be used to cool the windings of motors before the hydrogen is used for fuel. Either High Temperature Superconductors (HTS) or high purity metals such as copper or aluminum may be used in the motor windings. Superconductors have essentially zero electrical resistance to steady current. The electrical resistance of high purity aluminum or copper near liquid hydrogen temperature can be l/lOO* or less of the room temperature resistance. These conductors could provide higher motor efficiency than normal room-temperature motors achieve. But much more importantly, these conductors can carry ten to a hundred times more current than copper conductors do in normal motors operating at room temperature. This is a consequence of the low electrical resistance and of good heat transfer coefficients in boiling LH2. Thus the conductors can produce higher magnetic field strengths and consequently higher motor torque and power. Designs, analysis and actual cryogenic motor tests show that such cryogenic motors could produce three or more times as much power per unit weight as turbine engines can, whereas conventional motors produce only 1/5 as much power per weight as turbine engines. This summer work has been done with Litz wire to maximize the current density. The current is limited by the amount of heat it

  12. Altered free radical metabolism in acute mountain sickness: implications for dynamic cerebral autoregulation and blood-brain barrier function

    DEFF Research Database (Denmark)

    Bailey, D M; Evans, K A; James, P E

    2008-01-01

    We tested the hypothesis that dynamic cerebral autoregulation (CA) and blood-brain barrier (BBB) function would be compromised in acute mountain sickness (AMS) subsequent to a hypoxia-mediated alteration in systemic free radical metabolism. Eighteen male lowlanders were examined in normoxia (21% O...... developed clinical AMS (AMS+) and were more hypoxaemic relative to subjects without AMS (AMS-). A more marked increase in the venous concentration of the ascorbate radical (A(*-)), lipid hydroperoxides (LOOH) and increased susceptibility of low-density lipoprotein (LDL) to oxidation was observed during...

  13. Screening of various botanical extracts for antioxidant activity using DPPH free radical method.

    Science.gov (United States)

    Waqas, Muhammad Khurram; Saqib, Najam-Us; Rashid, Saeed-Ur; Shah, Pervaiz Akhtar; Akhtar, Naveed; Murtaza, Ghulam

    2013-01-01

    Aiming at the exploration of herbal use by society, crude extracts of the seeds of some commonly used medicinal plants (Vitis vinifera, Tamarindus indica and Glycin max) were screened for their free radical scavenging properties using ascorbic acid as standard antioxidant. Free radical scavenging activity was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical. The overall antioxidant activity of grape seeds (Vitis vinifera) was the strongest, followed in descending order by soybean (Glycin max) and tamarind (Tamarindus indica). The seeds extract of Vitis vinifera, Glycin max and Tamarindus indica showed 85.61%, 83.45% and 79.26%, DPPH scavenging activity respectively.

  14. Radiolytic oxidation of tamoxifen using the free radicals .OH and (or) HO2

    International Nuclear Information System (INIS)

    Leguene, C.; Clavere, P.; Jore, D.; Gardes-Albert, M.

    2001-01-01

    Tamoxifen is the most widely used antiestrogen in the treatment of breast cancer. In this work, we have studied its antioxidant properties. We have investigated the ability of tamoxifen to scavenge, in vitro, . OH and (or) HO 2 . free radicals that are produced by water radiolysis. Aqueous solutions of tamoxifen of concentrations ranging between 10 -5 and 2.5 x 10 -5 M have been irradiated (γ 137 Cs) in aerated acidic medium (H 3 PO 4 10 -3 M or HCOOH 10 -1 M). The results show that tamoxifen reacts quantitatively with . OH free radicals but does not react with HO 2 . free radicals under our experimental conditions. (author)

  15. EPR study of the free radicals in the spices and pigments turmeric and saffron

    International Nuclear Information System (INIS)

    Troup, G.J.; Hutton, D.R.; Hunter, C.A.; Hewitt, D.; Mulinacci, N.; Romani, A.; Giaccherini, K. Anon

    2000-01-01

    Full text: The spices Turmeric (curcuma longa) and Saffron (crocus sativus) have also been used as pigments. The EPR spectrum of each shows a readily detectable free radical signal. EPR spectra of the available pure chief active colorants in solid form also give free radical signals. Curcumin (turmeric) is a 'linear' symmetric phenolic, so is expected to do so. The peptide turmerin (commercially unavailable), containing sulphur, may also contribute to the ESR signal. Crocetin (saffron) is a 'linear' molecule, related to the beta-carotenes, which do not give free radical signals: but it does, presumably because of its particular resonant structure properties

  16. Innate catalytic and free radical scavenging activities of silver nanoparticles synthesized using Dillenia indica bark extract.

    Science.gov (United States)

    Mohanty, Alfa S; Jena, Bhabani S

    2017-06-15

    A green approach was envisaged for the rapid synthesis of stable silver nanoparticles in an aqueous medium using phenolic rich ethanolic bark extract from D. indica with marked free radical scavenging and reducing ability. Biosynthesis of silver nanoparticles (AgNPs) was confirmed and characterized by using UV-visible spectroscopy, particle size analyzer, X-ray diffractometry (XRD), Transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FT-IR). Bio-reduction of Ag+ was confirmed with the appearance of golden yellow coloration within 5-10min at 45°C with maximum absorbance at 421nm. XRD analysis of AgNPs indicated the crystalline nature of metallic Ag. As analyzed by TEM, AgNPs were found to be spherical in shape, well dispersed and size varied from 15 to 35nm and dynamic light scattering (DLS) studies showed the average particle size of 29nm with polydispersity index (PDI) of 0.280. Synthesized AgNPs were showing surface functionalization as revealed through FTIR studies. These AgNPs were observed to be highly stable at room temperature (28±2°C) for more than 3months, thereby indicating the ethanolic extract of D. indica was a reducing as well as a capping agent for stabilization of AgNPs. Moreover, these green synthesized AgNPs showed enhanced free radical scavenging and excellent catalytic activities when used in the reduction of 4-nitrophenol and methylene blue dye, at room temperature. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Photoisomerization and photodissociation dynamics of reactive free radicals

    Energy Technology Data Exchange (ETDEWEB)

    Bise, Ryan T. [Univ. of California, Berkeley, CA (United States)

    2000-08-01

    The photofragmentation pathways of chemically reactive free radicals have been examined using the technique of fast beam photofragment translational spectroscopy. Measurements of the photodissociation cross-sections, product branching ratios, product state energy distributions, and angular distributions provide insight into the excited state potential energy surfaces and nonadiabatic processes involved in the dissociation mechanisms. Photodissociation spectroscopy and dynamics of the predissociative $\\tilde{A}$2A1 and $\\tilde{B}$2A2 states of CH3S have been investigated. At all photon energies, CH3 + S(3Pj), was the main reaction channel. The translational energy distributions reveal resolved structure corresponding to vibrational excitation of the CH3 umbrella mode and the S(3Pj) fine-structure distribution from which the nature of the coupled repulsive surfaces is inferred. Dissociation rates are deduced from the photofragment angular distributions, which depend intimately on the degree of vibrational excitation in the C-S stretch. Nitrogen combustion radicals, NCN, CNN and HNCN have also been studied. For all three radicals, the elimination of molecular nitrogen is the primary reaction channel. Excitation to linear excited triplet and singlet electronic states of the NCN radical generates resolved vibrational structure of the N2 photofragment. The relatively low fragment rotational excitation suggests dissociation via a symmetric C2V transition state. Resolved vibrational structure of the N2 photofragment is also observed in the photodissociation of the HNCN radical. The fragment vibrational and rotational distributions broaden with increased excitation energy. Simple dissociation models suggest that the HNCN radical isomerizes to a cyclic intermediate (c-HCNN) which then dissociates via a tight cyclic

  18. Is brain copper deficiency in Alzheimer's, Lewy body, and Creutzfeldt Jakob diseases the common key for a free radical mechanism and oxidative stress-induced damage?

    Science.gov (United States)

    Deloncle, Roger; Guillard, Olivier

    2015-01-01

    In Alzheimer's (AD), Lewy body (LBD), and Creutzfeldt Jakob (CJD) diseases, similar pathological hallmarks have been described, one of which is brain deposition of abnormal protease-resistant proteins. For these pathologies, copper bound to proteins is able to protect against free radicals by reduction from cupric Cu++ to cupreous Cu+. We have previously demonstrated in bovine brain homogenate that free radicals produce proteinase K-resistant prion after manganese is substituted for copper. Since low brain copper levels have been described in transmissible spongiform encephalopathies, in substantia nigra in Parkinson's disease, and in various brain regions in AD, LBD, and CJD, a mechanism has been proposed that may underlie the neurodegenerative processes that occur when copper protection against free radicals is impaired. In peptide sequences, the alpha acid proton near the peptide bond is highly mobile and can be pulled out by free radicals. It will produce a trivalent α-carbon radical and induce a free radical chain process that will generate a D-amino acid configuration in the peptide sequence. Since only L-amino acids are physiologically present in mammalian (human) proteins, it may be supposed that only physiological L-peptides can be recycled by physiological enzymes such as proteases. If a D-amino acid is found in the peptide sequence subsequent to deficient copper protection against free radicals, it will not be recognized and might alter the proteasome L-amino acid recycling from brain peptides. In the brain, there will result an accumulation of abnormal protease-resistant proteins such as those observed in AD, LBD, and CJD.

  19. Delocalization model of regioselectivity and reactivity of free radicals in reactions of addition to olefins

    International Nuclear Information System (INIS)

    Volovik, S.V.; Dyadyusha, G.G.; Staninets, V.I.

    1987-01-01

    On the basis of the concept of polarity (philicity) of free radicals as proposed by the authors, within the framework of methods of qualitative surfaces of potential energy (linear combinations of configurations of fragments) and stabilization energy, an effective model has been developed for the regioselectivity and reactivity of radicals in processes of addition. A critical examination is made of certain key aspects of the change in regiochemistry and reactivity with changes in the electronic structure of the free radical and substrate. The dominant trends in regioselectivity and reactivity in processes of free-radical addition to olefins are controlled by electronic effects and can be predicted by analyzing interactions of diabatic potential energy surfaces or orbital interactions for a system consisting of a free radical and an unsaturated substrate

  20. Calorimetric and spectroscopic properties of small globular proteins (bovine serum albumin, hemoglobin) after free radical generation

    International Nuclear Information System (INIS)

    Farkas, N.; Belagyi, J.; Lorinczy, D.

    2003-01-01

    Mild oxidation of -SH-containing proteins (serum albumin, hemoglobin) by Ce(IV)-ions in the presence of the spin trap phenyl-tert-butylnitrone (PBN) resulted in the appearance of strongly immobilized nitroxide free radicals which evidences the formation of thiyl radicals on the thiol site of the proteins. In hydroxyl free radical generating system a fraction of strongly immobilized nitroxide radicals was also detected in these proteins, which implies that the oxidation of a fraction of the thiol groups was also involved in the free radical reaction. According to the differential scanning calorimetry (DSC) experiments the melting processes of the proteins were calorimetrically irreversible, therefore the two-state kinetic model was used to evaluate the experiments. The results support the view that site-specific interaction of SH-containing proteins with hydroxyl and thiyl free radicals is able to modify the internal dynamics of proteins and affect the conformation of large molecules

  1. The free radical process for the polymer surface treated by radio frequency plasma

    International Nuclear Information System (INIS)

    Ma Yuguang; Yang Meiling; Shen Jiacong; Zheng Yingguang

    1992-01-01

    The formation and translation of the free radicals on the polymer surface treated by plasmas were studied and observed by ESR measurement. The results show that C-C bond split was main reaction in the process of the polymer irradiated by plasma, by which a stable alkyl free radical was formed. When alkyl free radical contacted with air, they translate into peroxide radical instantaneously. The peroxide radical was not as stable as radical in vacuum, they can react each other to form some polar-groups on polymer surface. The interaction between the peroxide free radical and polymer chain was correlative not only to the structure of polymer but also to the molecular motion of the polymer chain. The nature of plasma treating polymer surface was that the peroxide radicals were led onto polymer surface

  2. Protective role of edible clam Paphia malabarica (Chemnitz) against lipid peroxidation and free radicals

    Digital Repository Service at National Institute of Oceanography (India)

    Pawar, R.T.; Nagvenkar, S.S.; Jagtap, T.G.

    In vitro inhibition of lipid peroxidation and free radical scavenging properties of a seafood Paphia malabarica (Chemnitz) as a natural source of antioxidants was observed. Antioxidant activities of Paphia malabarica extracts were tested...

  3. Comparative in vitro study on free radical scavenging potential of selected bivalve species

    Digital Repository Service at National Institute of Oceanography (India)

    Shenai-Tirodkar, P.S.; Pawar, R.T.; Jagtap, T.G.

    Bivalves such as, Crassostrea spp., Meretrix casta, Placuna placenta and Polymesoda erosa are largely consumed as edible seafood. It forms natural source of nutrition in coastal and worldwide population. Free radical scavenging activities...

  4. Free radical scavenging potential, reducing power, phenolic and biochemical constituents of Porphyra species from India

    Digital Repository Service at National Institute of Oceanography (India)

    Pise, N.M.; Jena, K.B.; Maharana, D.; Gaikwad, D.; Jagtap, T.G.

    . Antioxidant potentials of algae were assessed through phenolic content, 2, 2-diphenyl-1- picrylhydrazyl (DPPH) activity, hydrogen peroxide (H sub(2)O sub(2)), scavenging power and reducing potential. A dose-dependent free radical scavenging action against DPPH...

  5. Radiation-initiated free-radical fragmentation of biologically active glycerides

    International Nuclear Information System (INIS)

    Akhrem, A.A.; Kisel', M.A.; Shadyro, O.I.; Yurkova, I.L.

    1993-01-01

    Oxidation reactions of the free-radical type play a decisive role in the initial processes of radiation damage. The most suitable substrates for such reactions are lipids. Lipids are a basic structural element of biomembranes and are involved in the barrier function and biocatalytic activity of such membranes. Free-radical degradation of membrane lipids can lead to serious damage and ultimately to destruction of the living cell. A well-studied type of free-radical conversion of lipids is oxidation of polyunsaturated fatty acid residues, so-called peroxide oxidation of lipids. In this paper, using as examples dimyristoylphosphatidyl glycerol (DMPG), monoglycerides, and glycerophosphate, the authors investigated the possibility of free-radical degradation in compounds of a lipid nature containing the α,β-bifunctional group

  6. Relationship between human tooth enamel free radical concentration and radiation dose

    International Nuclear Information System (INIS)

    Zhou Yongzeng; Wang Jiadong; Jia Xiaomei; Wu Ke; Cong Jianbo; Sun Cunpu

    1999-01-01

    Free radical concentrations of 25 adult tooth enamel samples were measured by electron spin resonance (ESR) technique in this paper, and the relationship between free radical concentration of tooth enamel and radiation dose was also investigated. In the 25 adult enamel samples they are 16 male samples and 9 female samples, Ages of tooth donors range from 18-41 years. Difference in background ESR signal intensity between male and female samples was no observed; free radical concentration (or increment of radiation-induced free radical concentration) in tooth enamel increases linearly with increasing of radiation dose. In the case of radiation accident, the study results of this paper could be applied to dose estimation when conditions of ESR measurement of exposed individual tooth enamel are similar to measurement conditions of dose-effect calibration curve in this paper

  7. Direct Measurement of Free Radical Levels in the Brain After Cortical Ischemia Induced by Photothrombosis

    Czech Academy of Sciences Publication Activity Database

    Mareš, J.; Nohejlová, K.; Stopka, Pavel; Rokyta, R.

    2016-01-01

    Roč. 65, č. 5 (2016), s. 853-860 ISSN 0862-8408 Institutional support: RVO:61388980 Keywords : Free radicals * EPR * Focal ischemia * Brain * Photothrombosis Subject RIV: CA - Inorganic Chemistry Impact factor: 1.461, year: 2016

  8. Analysis of conformations and ESR spectra of free radicals in carbohydrates

    International Nuclear Information System (INIS)

    Abaghyan, G.V.; Abaghyan, A.G.; Apresyan, A.S.

    1998-01-01

    The conformations of free radicals arising when the unpaired electron is localized on carbon atoms in pyranose ring of carbohydrate molecule are considered. On the base of the analysis of expected conformations of radicals a possible contribution of β-protons in hyperfine structure of ESP spectra is predicted. The results of conformational analysis for different types of free radicals are in satisfactory agreement with the corresponding experimental data for the liquid phase. 17 refs

  9. Study of anti-oxidation and scavenging effects on free radicals of quercetin

    International Nuclear Information System (INIS)

    Wang Chongdao; Qiang Yizhong; Lao Qinhua; Shao Yuan

    1999-01-01

    The effects of Quercetin on the contents of lipid peroxides (LPO) in the mice caused by γ-whole-body irradiation by method of the modified spectrophotometry of TBA, and the scavenging effects of Quercetin on the free radicals of DNA induced by radiation exposure by means of ESR technique were investigated. The results demonstrates that Quercetin has a good anti-oxidation effect and is very effective in scavenging of free radicals

  10. Anti-oxidation and scavenging effects of some extracts from Chinese medicines on free radicals

    International Nuclear Information System (INIS)

    Wang Chongdao; Qiang Yizhong; Lao Qinhua; Cui Fengmei; Shao Yuan; Sun Cunpu

    1999-11-01

    The inhibiting effects of Chinonin, Quercetin and Tannic Acid on the lipid oxidation induced by radiation exposure were investigated by means of a modified TBA spectrophotometry. The scavenging effects on free radicals caused by γ-irradiation exposure of the three active principles were observed by technique of ESR. The results showed that anti-oxidation effects of Chinonin and Quercetin were better than that of Tannic Acid, while the scavenging effects of the three active principles on free radicals were similar

  11. Epigenetic oxidative redox shift (EORS) theory of aging unifies the free radical and insulin signaling theories

    OpenAIRE

    Brewer, Gregory J.

    2009-01-01

    Harman’s free radical theory of aging posits that oxidized macromolecules accumulate with age to decrease function and shorten life-span. However, nutritional and genetic interventions to boost antioxidants have generally failed to increase life-span. Furthermore, the free radical theory fails to explain why exercise causes higher levels of oxyradical damage, but generally promotes healthy aging. The separate anti-aging paradigms of genetic or caloric reductions in the insulin signaling pathw...

  12. Free radical reaction characteristics of coal low-temperature oxidation and its inhibition method.

    Science.gov (United States)

    Li, Zenghua; Kong, Biao; Wei, Aizhu; Yang, Yongliang; Zhou, Yinbo; Zhang, Lanzhun

    2016-12-01

    Study on the mechanism of coal spontaneous combustion is significant for controlling fire disasters due to coal spontaneous combustion. The free radical reactions can explain the chemical process of coal at low-temperature oxidation. Electron spin resonance (ESR) spectroscopy was used to measure the change rules of the different sorts and different granularity of coal directly; ESR spectroscopy chart of free radicals following the changes of temperatures was compared by the coal samples applying air and blowing nitrogen, original coal samples, dry coal samples, and demineralized coal samples. The fragmentation process was the key factor of producing and initiating free radical reactions. Oxygen, moisture, and mineral accelerated the free radical reactions. Combination of the free radical reaction mechanism, the mechanical fragmentation leaded to the elevated CO concentration, fracturing of coal pillar was more prone to spontaneous combustion, and spontaneous combustion in goaf accounted for a large proportion of the fire in the mine were explained. The method of added diphenylamine can inhibit the self-oxidation of coal effectively, the action mechanism of diphenylamine was analyzed by free radical chain reaction, and this research can offer new method for the development of new flame retardant.

  13. Kinetics of free radical reactions in irradiated crystalline L-leucine

    International Nuclear Information System (INIS)

    Dole, M.; Mahdavi, M.

    1983-01-01

    Four aspects of the radiation chemistry of crystalline L-leucine are presented. They are as follows: the transformation of one type of free radical into another as observed by following the ESR spectrum of individual peaks in the initial stages of the free radical decay at room or higher temperatures after a gamma irradiation at 77K; the catalytic effect of hydrogen gas in significantly accelerating the free radical decay; the unexpected effect of argon gas in decreasing the rate of the free radical decay; and the accurate agreement of the decay data with the diffusion controlled second order Waite equation when the latter is expressed in the linear form. The major free radical which exists in irradiated L-leucine gives rise to a spectrum of 8 Doublets for a total of 16 lines. Numbering the peaks from the least intense to the strongest, peaks numbers 3, 4, 6, and 7, initially increase in intensity before decreasing while peak number 5 rapidly decreases. However, during this initial period the total free radical concentration as measured by the total moment of the ESR spectrum decreases. The kinetics of these effects are discussed. (author)

  14. Dialogue between E. coli free radical pathways and the mitochondria of C. elegans.

    Science.gov (United States)

    Govindan, J Amaranath; Jayamani, Elamparithi; Zhang, Xinrui; Mylonakis, Eleftherios; Ruvkun, Gary

    2015-10-06

    The microbial world presents a complex palette of opportunities and dangers to animals, which have developed surveillance and response strategies to hints of microbial intent. We show here that the mitochondrial homeostatic response pathway of the nematode Caenorhabditis elegans responds to Escherichia coli mutations that activate free radical detoxification pathways. Activation of C. elegans mitochondrial responses could be suppressed by additional mutations in E. coli, suggesting that C. elegans responds to products of E. coli to anticipate challenges to its mitochondrion. Out of 50 C. elegans gene inactivations known to mediate mitochondrial defense, we found that 7 genes were required for C. elegans response to a free radical producing E. coli mutant, including the bZip transcription factor atfs-1 (activating transcription factor associated with stress). An atfs-1 loss-of-function mutant was partially resistant to the effects of free radical-producing E. coli mutant, but a constitutively active atfs-1 mutant growing on wild-type E. coli inappropriately activated the pattern of mitochondrial responses normally induced by an E. coli free radical pathway mutant. Carbonylated proteins from free radical-producing E. coli mutant may directly activate the ATFS-1/bZIP transcription factor to induce mitochondrial stress response: feeding C. elegans with H2O2-treated E. coli induces the mitochondrial unfolded protein response, and inhibition of a gut peptide transporter partially suppressed C. elegans response to free radical damaged E. coli.

  15. Free radicals and related reactive species as mediators of tissue injury and disease: implications for Health.

    Science.gov (United States)

    Kehrer, James P; Klotz, Lars-Oliver

    2015-01-01

    A radical is any molecule that contains one or more unpaired electrons. Radicals are normal products of many metabolic pathways. Some exist in a controlled (caged) form as they perform essential functions. Others exist in a free form and interact with various tissue components. Such interactions can cause both acute and chronic dysfunction, but can also provide essential control of redox regulated signaling pathways. The potential roles of endogenous or xenobiotic-derived free radicals in several human pathologies have stimulated extensive research linking the toxicity of numerous xenobiotics and disease processes to a free radical mechanism. In recent years, improvements in analytical methodologies, as well as the realization that subtle effects induced by free radicals and oxidants are important in modulating cellular signaling, have greatly improved our understanding of the roles of these reactive species in toxic mechanisms and disease processes. However, because free radical-mediated changes are pervasive, and a consequence as well as a cause of injury, whether such species are a major cause of tissue injury and human disease remains unclear. This concern is supported by the fact that the bulk of antioxidant defenses are enzymatic and the findings of numerous studies showing that exogenously administered small molecule antioxidants are unable to affect the course of most toxicities and diseases purported to have a free radical mechanism. This review discusses cellular sources of various radical species and their reactions with vital cellular constituents, and provides examples of selected disease processes that may have a free radical component.

  16. Investigation on the recombination kinetics of the pyrolytic free-radicals in the irradiated polyimide

    International Nuclear Information System (INIS)

    Sun Chengyue; Wu Yiyong; Yue Long; Shi Yaping; Xiao Jingdong

    2012-01-01

    Highlights: ► Free radicals behavior was exposure during the irradiation and anneal during the post storage. ► Both of the recombination and oxygen reaction affect the post-annealing evolution of free radicals. ► The activation energy and the surface reaction rate were calculated by the analysis of the free radical anneal process. - Abstract: The free radical behavior of 60 and 110 keV proton-irradiated polyimide were investigated using electron paramagnetic resonance measurements. The results indicate that during proton irradiation, a type of pyrolytic carbon free radical was formed with a g value of 2.0025. The radical population was found, after proton irradiation to decrease in a combination of an exponential and linear modes with an annealing time in the range of 50–120 °C. The exponential part indicated a radical recombination process while the linear part is due to the reaction of the radical with the ambient. Using the annealing results, the recombination activation energy of the radicals was determined as 12.4 ± 0.2 and 17.6 ± 0.2 kJ/mol for 60 and 110 keV irradiated polyimide, respectively, with a surface reaction rate of about 0.02/h. It is possible that the kinetic study presented here is used as one of the criteria for predicting the optical properties of polyimide material in spacecraft. The mechanism of the free radical evolution will be discussed in this paper.

  17. Retardative chain transfer in free radical free-radical polymerisations of vinyl neo-decanoate in low molecular weight polyisoprene and toluene

    NARCIS (Netherlands)

    Monteiro, M.J.; Subramaniam, N.; Taylor, J.R.; Pham, B.T.T.; Tonge, M.P.; Gilbert, R.G.

    2001-01-01

    The kinetics of free-radical polymerisation of vinyl neo-decanoate (VneoD) and the molecular weight distributions (MWDs) of the polymers formed in the presence and absence of low molecular weight polyisoprene at 50°C under a variety of conditions were investigated. The bulk reaction was successfully

  18. High-density polyethylene dosimetry by transvinylene FTIR analysis

    DEFF Research Database (Denmark)

    McLaughlin, W.L.; Silverman, J.; Al-Sheikhly, M.

    1999-01-01

    and electrons. The useful dose range of 0.053 cm thick high-density polyethylene film (rho = 0.961 g cm(-3); melt index = 0.8 dg min(-1)), for irradiations by (60)Co gamma radiation and 2.0 and 0.4 MeV electron beams in deaerated atmosphere (Na gas), is about 50-10(3) kGy for FTIR transvinylene......The formation of transvinylene unsaturation, -CH=CH-, due to free-radical or cationic-initiated dehydrogenation by irradiation, is a basic reaction in polyethylene and is useful for dosimetry at high absorbed doses. The radiation-enhanced infrared absorption having a maximum at nu = 965 cm......(-l) (lambda = 10.36 mu m) is stable in air and can be measured by Fourier-transform infrared (FTIR) spectrophotometry. The quantitative analysis is a useful means of product end-point dosimetry for radiation processing with gamma rays and electrons, where polyethylene is a component of the processed product...

  19. The free-radical scavenger edaravone accelerates thrombolysis with alteplase in an experimental thrombosis model.

    Science.gov (United States)

    Yamashita, Tsutomu; Sato, Takumi; Sakamoto, Kumi; Ishii, Hiromitsu; Yamamoto, Junichiro

    2015-06-01

    Reperfusion injury after thrombolytic therapy can have adverse neurologic effects. The free-radical scavenger edaravone is used in combination with the recombinant tissue plasminogen activator alteplase to treat acute ischemic stroke. However, basic investigations of this combination use remain inadequate. Here, we used an in vivo model to investigate the effects of edaravone on alteplase-induced thrombolysis. Thrombolysis was evaluated by using a He-Ne-laser-induced thrombosis model in rat mesenteric microvessels. Changes in thrombus volume were analyzed with the image analysis software Image-Pro Plus (Media Cybernetics, USA). There were three experimental groups (placebo, alteplase 0.6 mg/kg, alteplase 0.6 mg/kg + edaravone 10.5 mg/kg). Sequential changes (0 to 60 min) in thrombus volume were compared by using a relative optical density method that we had used previously. In the placebo group, the thrombus volume at 60 min, reflecting the extent of thrombolysis, was 97.2% ± 5.7% of the initial value. In the alteplase group, thrombus volume decreased to 70.7% ± 4.1% (Pedaravone group, thrombus volume decreased to 66.9% ± 7.2% (Pedaravone accelerates thrombolysis by alteplase. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. EPR studies of the free radicals generated in gamma irradiated amino acid derivatives

    Science.gov (United States)

    Osmanoğlu, Y. Emre; Sütçü, Kerem

    2017-10-01

    Gamma irradiated powder forms of N-acetyl-DL-aspartic acid, N-carbamoyl-DL-aspartic acid and N-methyl-L-serine were investigated by electron paramagnetic resonance spectroscopy (EPR) at room temperature. In these compounds, the paramagnetic centers formed after irradiation were attributed to the HOOCCH2ĊHCOOH, COOHĊHCHNH and HOCH2ĊHCOOH radicals, respectively. The g values and the hyperfine coupling constants for the radical species are with values of g = 2.0038 ± 0.0005, aα = 2.15 mT, aβ(1) = 3.84 mT and aβ(2) = 2.15 for the first radical, g = 2.0039 ± 0.0005, aα = 1.7 mT, aß(1) = 0.62 mT, aß(2) = 0.54 mT, aγ = 0.53 mT for the second radical and g = 2.0039 ± 0.0005, aβ(1) = 2.40 mT, aβ(2) = 1.83 mT and aα = 1.83 mT for the third radical. The free radicals formed in three compounds were found to be stable for three months at room temperature. It was concluded that, spin density was concentrated predominantly in the 2pπ orbital of the carbon atom.

  1. Role of the reacting free radicals on the antioxidant mechanism of curcumin

    Energy Technology Data Exchange (ETDEWEB)

    Galano, Annia, E-mail: agalano@prodigy.net.mx [Universidad Autonoma Metropolitana-Iztapalapa, Departamento de Quimica, Area de Quimica Analitica, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, C.P. 09340, Mexico D.F. (Mexico); Alvarez-Diduk, Ruslan; Ramirez-Silva, Maria Teresa; Alarcon-Angeles, Georgina; Rojas-Hernandez, Alberto [Universidad Autonoma Metropolitana-Iztapalapa, Departamento de Quimica, Area de Quimica Analitica, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, C.P. 09340, Mexico D.F. (Mexico)

    2009-09-18

    Density functional theory is used to study the antioxidant mechanism of curcumin. Five different mechanisms are considered: single electron transfer (SET), radical adduct formation (RAF), H atom transfer from neutral curcumin (HAT), H atom transfer from deprotonated curcumin (HAT-D), and sequential proton loss electron transfer (SPLET). The influence of the environment is investigated for polar and non-polar surroundings. The apparent contradictions among previous experimental results are explained by the role of the nature of the reacting free radical on the relative importance of the above mentioned mechanism. It is proposed that the curcumin + DPPH reaction actually takes place mainly through the SPLET mechanism, while the reaction with {sup {center_dot}}OCH{sub 3}, and likely with other alkoxyl radicals, is governed by the HAT mechanism. Branching ratios for the {sup {center_dot}}OCH{sub 3} + curcumin reaction are reported for the first time. The calculated overall rate constants for this reaction are 1.16 x 10{sup 10} (benzene) and 5.52 x 10{sup 9} (water) L mol{sup -1} s{sup -1}. The role of phenolic groups on the antioxidant activity of curcumin has been experimentally confirmed.

  2. Environmentally Persistent Free Radicals in Soils of Past Coking Sites: Distribution and Stabilization.

    Science.gov (United States)

    Jia, Hanzhong; Zhao, Song; Nulaji, Gulimire; Tao, Kelin; Wang, Fu; Sharma, Virender K; Wang, Chuanyi

    2017-06-06

    This study presents the existence of environmentally persistent free radicals (EPFRs) in soils of past coking sites, mainly contaminated by polycyclic aromatic hydrocarbons (PAHs). Measurements of EPFRs were conducted by electron paramagnetic resonance (EPR) technique with numerous soil samples, which were collected from different distances (0-1000 m) and different depths (0-30 cm) of three contaminant sources. EPR signals with ∼3 × 10 17 radicals/g of the soil samples were obtained, which are very similar to that generated in PAHs contaminated clays, that is, g = 2.0028-2.0036. Concentrations of PAHs and soil components were determined to understand their role in producing EPFRs. PAHs, clay, and iron predominately contributed to generating EPRFs. Meanwhile, organic matter negatively influenced the production of EPRFs. The effects of environmental factors (moisture and oxic/anoxic) were also studied to probe the persistency of EPFRs under various simulated conditions. The EPFRs are stable under relatively dry and oxic conditions. Under anoxic conditions without O 2 and H 2 O, the spin densities decrease initially, followed by gradual increase before attaining constant values in two months period time. The present work implies that continuous formation of EPFRs induced by PAHs is largely responsible for the presence of relatively stable radicals in soils of coking sites.

  3. Free-radical-induced chain scission and cross-linking of polymers in aqueous solution. An overview

    International Nuclear Information System (INIS)

    Von Sonntag, C.

    2002-01-01

    Complete text of publication follows. In the radiolysis of N 2 O-saturated aqueous solutions OH are generated. In their reactions with polymers, they give rise to polymer-derived radicals. The kinetics of the formation and decay of these radicals are reviewed. The rate of reaction of a polymer with a reactive free radical is noticeably lower than that of an equivalent concentration of monomer due to the non-random distribution of the reaction sites. Once a larger number of radicals are formed on one polymer molecule, e.g. upon pulse radiolysis, close-by radicals recombine more rapidly while the more distant ones survive for much longer times than an equivalent concentration of freely diffusing radicals. Intermolecular cross-linking (between two polymer chains, increase in molecular weight) and intramolecular cross-linking (formation of small loops, no increase in polymer weight) are competing processes, and their relative yields thus depend on the dose rate and polymer concentration. Hydrogen-transfer reactions within the polymer, e.g. transformation of a secondary radical into a tertiary one, are common and facilitated by the high local density of reactive sites. Due to repulsive forces, the lifetime of radicals of charged polymers is substantially increased. This enables even relatively slow b-fragmentation reactions to become of importance. In the case of poly(methacrylic acid), where β-fragmentation is comparatively fast, this even leads to an unzipping, and as a consequence of the efficient release of methacrylic acid the situation of equilibrium polymerization is approached. Heterolytic β-fragmentation is possible when adequate leaving groups are available, e.g. in polynucleotides and DNA. In the presence of O 2 , chain scission occurs via oxyl radicals as intermediates. Some implications for technical applications are discussed

  4. OKN-007 decreases free radical levels in a preclinical F98 rat glioma model.

    Science.gov (United States)

    Coutinho de Souza, Patricia; Smith, Nataliya; Atolagbe, Oluwatomisin; Ziegler, Jadith; Njoku, Charity; Lerner, Megan; Ehrenshaft, Marilyn; Mason, Ronald P; Meek, Bill; Plafker, Scott M; Saunders, Debra; Mamedova, Nadezda; Towner, Rheal A

    2015-10-01

    Free radicals are associated with glioma tumors. Here, we report on the ability of an anticancer nitrone compound, OKN-007 [Oklahoma Nitrone 007; a disulfonyl derivative of α-phenyl-tert-butyl nitrone (PBN)] to decrease free radical levels in F98 rat gliomas using combined molecular magnetic resonance imaging (mMRI) and immunospin-trapping (IST) methodologies. Free radicals are trapped with the spin-trapping agent, 5,5-dimethyl-1-pyrroline N-oxide (DMPO), to form DMPO macromolecule radical adducts, and then further tagged by immunospin trapping by an antibody against DMPO adducts. In this study, we combined mMRI with a biotin-Gd-DTPA-albumin-based contrast agent for signal detection with the specificity of an antibody for DMPO nitrone adducts (anti-DMPO probe), to detect in vivo free radicals in OKN-007-treated rat F98 gliomas. OKN-007 was found to significantly decrease (P free radical levels detected with an anti-DMPO probe in treated animals compared to untreated rats. Immunoelectron microscopy was used with gold-labeled antibiotin to detect the anti-DMPO probe within the plasma membrane of F98 tumor cells from rats administered anti-DMPO in vivo. OKN-007 was also found to decrease nuclear factor erythroid 2-related factor 2, inducible nitric oxide synthase, 3-nitrotyrosine, and malondialdehyde in ex vivo F98 glioma tissues via immunohistochemistry, as well as decrease 3-nitrotyrosine and malondialdehyde adducts in vitro in F98 cells via ELISA. The results indicate that OKN-007 effectively decreases free radicals associated with glioma tumor growth. Furthermore, this method can potentially be applied toward other types of cancers for the in vivo detection of macromolecular free radicals and the assessment of antioxidants. Copyright © 2015. Published by Elsevier Inc.

  5. Polyphenolic Compounds and Free Radical Scavenging Activity in Eight Lamiaceae Herbs of Manipur

    Directory of Open Access Journals (Sweden)

    Sandhyarani Devi KHOMDRAM

    2011-05-01

    Full Text Available Eight plants of Lamiaceae under subfamily Nepetoideae found in Manipur, India were selected for estimation of their polyphenolic compounds and free radical scavenging activity which is expressed on dry weight basis. In this present study, the total phenol and flavonoid contents as well as the free radical scavenging activity were studied using spectrophotometric method. The total phenol content was determined based on Folin-Ciocalteau reagent, flavonoid was determined by aluminium chloride spectrophotometric method and tannin by Folin Dennis Method. The free radical scavenging activity was determined by using DPPH radical which is expressed as IC50 (μg/ml. The total phenolic content varied from 21.39±0.927 to 46.28±0.543 mg/g, flavonoids content in the selected samples varied from 13.30±0.684 to 26.03±0.217 mg/g and tannin content varied from 8.72±0.160 to 17.04±0.206 mg/g. The free radical scavenging activity among the selected samples varied from 11.67±0.221 to 38.29±0.532 μg/ml. The correlation between the free radical scavenging activity with total phenol content (R2=0.511, with flavonoids (R2=0.241 and with tannin (R2=0.690 was calculated and maximum correlation value was found between tannin content and the free radical scavenging activity of the plant samples. The result supports that tannins were more responsible for free radical scavenging activity in the presently selected plants.

  6. Free radical scavenging and anti-oxidative activities of an ethanol-soluble pigment extract prepared from fermented Zijuan Pu-erh tea.

    Science.gov (United States)

    Fan, Jiang Ping; Fan, Chong; Dong, Wen Min; Gao, Bin; Yuan, Wei; Gong, Jia Shun

    2013-09-01

    An ethanol-soluble pigment extract was separated from fermented Zijuan Pu-erh tea. The compositions of the ethanol soluble pigment extract were analyzed by high-performance liquid chromatography-tandem mass spectroscopy (HPLC-MS/MS). The extract was prepared into a series of ethanol solutions and analyzed for free radical-scavenging activities (against two free radicals: 1,1-diphenyl-2-picrylhydrazyl (DPPH) and (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)) and in vitro anti-oxidative properties. Electron spin resonance spectroscopy showed that the peaks of DPPH and TEMPO decreased with increasing extract concentration, suggesting that the extract had excellent free radical-scavenging activities. In vitro cell culture suggested that, at 50-200 mg/L, the extract had no measurable effect on the viability of vascular endothelial cells (ECV340) but produced significant protective effects for cells that underwent oxidative injuries due to hydrogen peroxide (H₂O₂) treatment. Compared with the H₂O₂ treatment alone cells group, 200 mg/L of the extract increased the activity of superoxide dismutase (SOD) in cells by 397.3%, and decreased the concentration of malondialdehyde (MDA) and the activity of lactate acid dehydrogenase (LDH) by 47.8% and 69.6%, respectively. These results suggest that the extract has excellent free radical scavenging and anti-oxidative properties. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. FREE-RADICAL OXIDATION ACTIVITY IN PATIENTS WITH ACUTE MYOCARDIAL INFARCTION WITHOUT Q WAVE TREATED WITH EPROSARTAN OR ENALAPRIL ADDITIONALLY TO THE BASIC THERAPY

    Directory of Open Access Journals (Sweden)

    O. G. Zaylobidinov

    2009-01-01

    Full Text Available Aim. To compare effects of eprosartan and enalapril on free-radical oxidation in patients with acute myocardial infarction (AMI without Q wave.Material and methods. 50 patients (aged 52,8±3,3 y.o. with AMI without Q were involved into the study. Patients were randomized on 2 groups. The first group consisted of 24 patients (51,1±2,4 y.o. which received basic therapy and enalapril (10 mg daily. The second group consisted of 26 patients (53,1±3,0 y.o. which received basic therapy and eprosartan (600 mg daily. Basic therapy included anticoagulants, antiplatelets, beta-blockers, nitrates and statins. Intensity of free-radical oxidation was evaluated by change of serum malonic dialdehyde (MDD concentration. Functional activity of serum enzymes of antioxidatic system (AOS was evaluated by rate of reaction of superoxide dismutase (SOD and catalase (CT.Results. The intensity of free-radical oxidation increased in patients with AMI without Q: high level of MDD and peroxinitrite (ONOO-. Besides activity of AOS enzymes (SOD and CT decreased. Eprosartan reduced intensity of peroxide oxidation more prominently in comparison with enalapril. Both drugs preserved low activity of SOD and CT.Conclusion. Eprosartan was significantly more effective than enalapril in reduction of serum free-radical oxidation in patients with AMI without Q wave during 10 days after hospital admission.

  8. Surface PEGylation of mesoporous silica materials via surface-initiated chain transfer free radical polymerization: Characterization and controlled drug release.

    Science.gov (United States)

    Huang, Long; Liu, Meiying; Mao, Liucheng; Huang, Qiang; Huang, Hongye; Wan, Qing; Tian, Jianwen; Wen, Yuanqing; Zhang, Xiaoyong; Wei, Yen

    2017-12-01

    As a new type of mesoporous silica materials with large pore diameter (pore size between 2 and 50nm) and high specific surface areas, SBA-15 has been widely explored for different applications especially in the biomedical fields. The surface modification of SBA-15 with functional polymers has demonstrated to be an effective way for improving its properties and performance. In this work, we reported the preparation of PEGylated SBA-15 polymer composites through surface-initiated chain transfer free radical polymerization for the first time. The thiol group was first introduced on SBA-15 via co-condensation with γ-mercaptopropyltrimethoxysilane (MPTS), that were utilized to initiate the chain transfer free radical polymerization using poly(ethylene glycol) methyl ether methacrylate (PEGMA) and itaconic acid (IA) as the monomers. The successful modification of SBA-15 with poly(PEGMA-co-IA) copolymers was evidenced by a series of characterization techniques, including 1 H NMR, FT-IR, TGA and XPS. The final SBA-15-SH- poly(PEGMA-co-IA) composites display well water dispersity and high loading capability towards cisplatin (CDDP) owing to the introduction of hydrophilic PEGMA and carboxyl groups. Furthermore, the CDDP could be released from SBA-15-SH-poly(PEGMA-co-IA)-CDDP complexes in a pH dependent behavior, suggesting the potential controlled drug delivery of SBA-15-SH-poly(PEGMA-co-IA). More importantly, the strategy should be also useful for fabrication of many other functional materials for biomedical applications owing to the advantages of SBA-15 and well monomer adoptability of chain transfer free radical polymerization. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Free Radical Imaging Using In Vivo Dynamic Nuclear Polarization-MRI.

    Science.gov (United States)

    Utsumi, Hideo; Hyodo, Fuminori

    2015-01-01

    Redox reactions that generate free radical intermediates are essential to metabolic processes, and their intermediates can produce reactive oxygen species, which may promote diseases related to oxidative stress. The development of an in vivo electron spin resonance (ESR) spectrometer and its imaging enables us noninvasive and direct measurement of in vivo free radical reactions in living organisms. The dynamic nuclear polarization magnetic resonance imaging (DNP-MRI), also called PEDRI or OMRI, is also a new imaging method for observing free radical species in vivo. The spatiotemporal resolution of free radical imaging with DNP-MRI is comparable with that in MRI, and each of the radical species can be distinguished in the spectroscopic images by changing the frequency or magnetic field of ESR irradiation. Several kinds of stable nitroxyl radicals were used as spin probes to detect in vivo redox reactions. The signal decay of nitroxyl probes, which is determined with in vivo DNP-MRI, reflects the redox status under oxidative stress, and the signal decay is suppressed by prior administration of antioxidants. In addition, DNP-MRI can also visualize various intermediate free radicals from the intrinsic redox molecules. This noninvasive method, in vivo DNP-MRI, could become a useful tool for investigating the mechanism of oxidative injuries in animal disease models and the in vivo effects of antioxidant drugs. © 2015 Elsevier Inc. All rights reserved.

  10. [In vitro anti-inflammatory and free radical scavenging activities of flavans from Ilex centrochinensis].

    Science.gov (United States)

    Li, Lu-jun; Yu, Li-juan; Li, Yan-ci; Liu, Meng-yuan; Wu, Zheng-zhi

    2015-04-01

    This study was carried out to evaluate the anti-inflammatory and free radical scavenging activities of flavans from flex centrochinensis S. Y. Hu in vitro and their structure-activity relationship. LPS-stimulated RAW 264.7 macrophage was used as inflammatory model. MTT assay for cell availability, Griess reaction for nitric oxide (NO) production, the content of TNF-alpha, IL-1beta, IL-6 and PGE, were detected with ELISA kits; DPPH, superoxide anion and hydroxyl free radicals scavenging activities were also investigated. According to the result, all flavans tested exhibited anti-inflammatory effect in different levels. Among them, compounds 1, 3, 4 and 6 showed potent anti-inflammatory effect through the inhibition of NO, TNF-alpha, IL-lp and IL-6, of which 1 was the most effective inhibitor, however, 2 and 5 were relatively weak or inactive. The order of free radical scavenging activities was similar to that of anti-inflammatory activities. Therefore, these results suggest that 3, 4 and 6, especially of 1, were,in part responsible for the anti-inflammatory and free radical scavenging activity of Ilex centrochinensis. Hydroxyl group at 4'-position of B-ring plays an important role in the anti-inflammatory and free radical scavenging capacities.

  11. Free radical scavenging window of infertile patients with polycystic ovary syndrome: correlation with embryo quality.

    Science.gov (United States)

    Huang, Bo; Li, Zhou; Ren, Xinling; Ai, Jihui; Zhu, Lixia; Jin, Lei

    2017-06-01

    The activity of free radicals in follicular fluid was related to ovarian responsiveness, in vitro fertilization (IVF), and embryo transfer success rate. However, studies analyzing the relationship between the free radical scavenging capacity and embryo quality of infertile women with polycystic ovarian syndrome (PCOS) were lacking. The aim of this study was to evaluate the relationship between the free radical scavenging window of women with PCOS and their embryo quality. The free radical scavenging capacity of follicular fluid from women with PCOS was determined by a,a-diphenyl-b-picrylhydrazyl (DPPH), 2,2-azinobis (3-ethylbenzthiazoline-6-sulphonic acid) assay, superoxide radical, and reactive oxygen species (ROS) assay. In the DPPH and ROS assays, the follicular fluid from grades I and II embryos was significantly higher than the follicular fluid from grades III and IVembryos. The lower control limit of DPPH radical scavenging capacity and upper control limit of ROS level were 13.2% and 109.0 cps, respectively. The calculated lower control limit and upper control limit were further confirmed in the follicular fluid of embryos of all grades. These cut-off values of free radical scavenging activity of follicular fluid could assist embryologists in choosing the development of embryos in PCOS patients undergoing IVF.

  12. Free radical scavenging activity of coenzyme Q measured by a chemiluminescent assay

    International Nuclear Information System (INIS)

    Battino, Maurizio; Ferri, Elida; Girotti, Stefano; Lenaz, Giorgio

    1991-01-01

    Involvement of coenzyme Q (CoQ) in anti-oxydant activities, in addition to its major redox role, has frequently been suggested in recent years. In order to elucidate if CoQ could really be engaged in scavenging free radicals produced endogenously in a biological system, an experimental system was developed in which beef heart mitochondria in the presence of a saturating NADH concentration and of rotenone produce free radicals. The presence of oxygen-reactive forms was easily detected by a luminol-dependent chemiluminescence process. The chemi-luminescence assay showed that short-chain CoQ homologues can act as pro-oxidants, enhancing free radical effects, while exogenous coenzyme Q 10 could scavenge free radicals, especially at very low concentration. In this system, exogenous CoQ 10 was more effective than α-tocopherol at the same concentration in scavenging free radicals. The molecular mechanism that leads to this activity is still unclear, but these results are of biochemical importance because they indicate that CoQ may act as an anti=oxidant in situations mimicking physiopathological conditions. This direct chemiluminescent method is promising for studies of biochemical processes which involve active oxygen species. (author). 24 refs.; 4 figs

  13. The efficacy of edaravone (radicut), a free radical scavenger, for cardiovascular disease.

    Science.gov (United States)

    Kikuchi, Kiyoshi; Tancharoen, Salunya; Takeshige, Nobuyuki; Yoshitomi, Munetake; Morioka, Motohiro; Murai, Yoshinaka; Tanaka, Eiichiro

    2013-07-04

    Edaravone was originally developed as a potent free radical scavenger, and has been widely used to treat acute ischemic stroke in Japan since 2001. Free radicals play an important role in the pathogenesis of a variety of diseases, such as cardiovascular diseases and stroke. Therefore, free radicals may be targets for therapeutic intervention in these diseases. Edaravone shows protective effects on ischemic insults and inflammation in the heart, vessel, and brain in experimental studies. As well as scavenging free radicals, edaravone has anti-apoptotic, anti-necrotic, and anti-cytokine effects in cardiovascular diseases and stroke. Edaravone has preventive effects on myocardial injury following ischemia and reperfusion in patients with acute myocardial infarction. Edaravone may represent a new therapeutic intervention for endothelial dysfunction in the setting of atherosclerosis, heart failure, diabetes, or hypertension, because these diseases result from oxidative stress and/or cytokine-induced apoptosis. This review evaluates the potential of edaravone for treatment of cardiovascular disease, and covers clinical and experimental studies conducted between 1984 and 2013. We propose that edaravone, which scavenges free radicals, may offer a novel option for treatment of cardiovascular diseases. However, additional clinical studies are necessary to verify the efficacy of edaravone.

  14. The Efficacy of Edaravone (Radicut, a Free Radical Scavenger, for Cardiovascular Disease

    Directory of Open Access Journals (Sweden)

    Eiichiro Tanaka

    2013-07-01

    Full Text Available Edaravone was originally developed as a potent free radical scavenger, and has been widely used to treat acute ischemic stroke in Japan since 2001. Free radicals play an important role in the pathogenesis of a variety of diseases, such as cardiovascular diseases and stroke. Therefore, free radicals may be targets for therapeutic intervention in these diseases. Edaravone shows protective effects on ischemic insults and inflammation in the heart, vessel, and brain in experimental studies. As well as scavenging free radicals, edaravone has anti-apoptotic, anti-necrotic, and anti-cytokine effects in cardiovascular diseases and stroke. Edaravone has preventive effects on myocardial injury following ischemia and reperfusion in patients with acute myocardial infarction. Edaravone may represent a new therapeutic intervention for endothelial dysfunction in the setting of atherosclerosis, heart failure, diabetes, or hypertension, because these diseases result from oxidative stress and/or cytokine-induced apoptosis. This review evaluates the potential of edaravone for treatment of cardiovascular disease, and covers clinical and experimental studies conducted between 1984 and 2013. We propose that edaravone, which scavenges free radicals, may offer a novel option for treatment of cardiovascular diseases. However, additional clinical studies are necessary to verify the efficacy of edaravone.

  15. Radiation inactivation analysis of enzymes. Effect of free radical scavengers on apparent target sizes

    International Nuclear Information System (INIS)

    Eichler, D.C.; Solomonson, L.P.; Barber, M.J.; McCreery, M.J.; Ness, G.C.

    1987-01-01

    In most cases the apparent target size obtained by radiation inactivation analysis corresponds to the subunit size or to the size of a multimeric complex. In this report, we examined whether the larger than expected target sizes of some enzymes could be due to secondary effects of free radicals. To test this proposal we carried out radiation inactivation analysis on Escherichia coli DNA polymerase I, Torula yeast glucose-6-phosphate dehydrogenase, Chlorella vulgaris nitrate reductase, and chicken liver sulfite oxidase in the presence and absence of free radical scavengers (benzoic acid and mannitol). In the presence of free radical scavengers, inactivation curves are shifted toward higher radiation doses. Plots of scavenger concentration versus enzyme activity showed that the protective effect of benzoic acid reached a maximum at 25 mM then declined. Mannitol alone had little effect, but appeared to broaden the maximum protective range of benzoic acid relative to concentration. The apparent target size of the polymerase activity of DNA polymerase I in the presence of free radical scavengers was about 40% of that observed in the absence of these agents. This is considerably less than the minimum polypeptide size and may reflect the actual size of the polymerase functional domain. Similar effects, but of lesser magnitude, were observed for glucose-6-phosphate dehydrogenase, nitrate reductase, and sulfite oxidase. These results suggest that secondary damage due to free radicals generated in the local environment as a result of ionizing radiation can influence the apparent target size obtained by this method

  16. Regulated production of free radicals by the mitochondrial electron transport chain: Cardiac ischemic preconditioning.

    Science.gov (United States)

    Matsuzaki, Satoshi; Szweda, Pamela A; Szweda, Luke I; Humphries, Kenneth M

    2009-11-30

    Excessive production of free radicals by mitochondria is associated with, and likely contributes to, the progression of numerous pathological conditions. Nevertheless, the production of free radicals by the mitochondria may have important biological functions under normal or stressed conditions by activating or modulating redox-sensitive cellular signaling pathways. This raises the intriguing possibility that regulated mitochondrial free radical production occurs via mechanisms that are distinct from pathologies associated with oxidative damage. Indeed, the capacity of mitochondria to produce free radicals in a limited manner may play a role in ischemic preconditioning, the phenomenon whereby short bouts of ischemia protect from subsequent prolonged ischemia and reperfusion. Ischemic preconditioning can thus serve as an important model system for defining regulatory mechanisms that allow for transient, signal-inducing, production of free radicals by mitochondria. Defining how these mechanism(s) occur will provide insight into therapeutic approaches that minimize oxidative damage without altering normal cellular redox biology. The aim of this review is to present and discuss evidence for the regulated production of superoxide by the electron transport chain within the ischemic preconditioning paradigm of redox regulation.

  17. Effect of shear stress and free radicals induced by ultrasound on erythrocytes

    International Nuclear Information System (INIS)

    Kondo, T.; Fukushima, Y.; Kon, H.; Riesz, P.

    1989-01-01

    The present study was undertaken to elucidate the mechanism of hemolysis induced by ultrasound. Ar or N2O gas was used to distinguish between cavitation with or without free radical formation (hydroxyl radicals and hydrogen atoms). Free radical formation was examined by the method of spin trapping combined with ESR. After sonication of erythrocyte suspensions, several structural and functional parameters of the erythrocyte membrane--hemolysis, membrane fluidity, membrane permeability, and membrane deformability--were examined. Although free radical formation was observed in the erythrocyte suspensions sonicated in the presence of Ar, no free radical formation was observed in the presence of N2O. However, the hemolysis behavior induced by ultrasound was similar in the presence of Ar or N2O. The membrane fluidity, permeability, and deformability of the remaining unlysed erythrocytes after sonication in the presence of Ar or N2O were unchanged and identical to those of the control cells. On the other hand, after gamma irradiation (700 Gy), the hemolysis behavior was quite different from that after sonication, and the membrane properties were significantly changed. These results suggest that hemolysis induced by sonication was due to mechanical shearing stress arising from cavitation, and that the membrane integrity of the remaining erythrocytes after sonication was the same as that of control cells without sonication. The triatomic gas, N2O, may be useful for ultrasonically disrupting cells without accompanying free radical formation

  18. Distribution of stable free radicals among amino acids of isolated soy proteins.

    Science.gov (United States)

    Lei, Qingxin; Liebold, Christopher M; Boatright, William L; Shah Jahan, M

    2010-09-01

    Application of deuterium sulfide to powdered isolated soy proteins (ISP) was used to quench stable free radicals and produce a single deuterium label on amino acids where free radicals reside. The deuterium labels rendered increases of isotope ratio for the specific ions of radical-bearing amino acids. Isotope ratio measurements were achieved by gas chromatography/mass spectrometry (GC/MS) analyses after the amino acids were released by acidic hydrolysis and converted to volatile derivatives with propyl chloroformate. The isotope enrichment data showed the stable free radicals were located on Ala, Gly, Leu, Ile, Asx (Asp+Asn), Glx (Glu+Gln), and Trp but not on Val, Pro, Met, Phe, Lys, and His. Due to the low abundance of Ser, Thr, and Cys derivatives and the impossibility to accurately measure their isotope ratios, the radical bearing status for these amino acids remained undetermined even though their derivatives were positively identified from ISP hydrolysates. The relative isotope enrichment for radical-bearing amino acids Ala, Gly, Leu, Ile, Asx (Asp+Asn), Glx (Glu+Gln), and Trp were 8.67%, 2.96%, 2.90%, 3.94%, 6.03%, 3.91%, and 21.48%, respectively. Isotope ratio increase for Tyr was also observed but further investigation revealed such increase was mainly from nonspecific deuterium-hydrogen exchange not free radical quenching. The results obtained from the present study provide important information for a better understanding of the mechanisms of free radical formation and stabilization in "dry" ISP.

  19. Study On DPPH Free Radical - Scavenging Activity Of Antioxidant Compounds In Plants Composing BIN-5 Biological Active Preparation

    Directory of Open Access Journals (Sweden)

    Purevjav Urjintseren

    2015-08-01

    Full Text Available Recently there has been common trend among people to refuse from food and medications produced via synthetic method but try to consume natural products as much as possible instead. In this regard wild berries and medicinal plants are considered to be highly essential for human health as these kinds of plants serve as rich sources of biological active substances-phenol compounds. As a result of conducting research on source and spread of herbs which are commonly used as anti-diabetic medication we have developed a technological method to extract preparations from medicinal herbs such as Peony Paeonia lactiflora Pall Dandelion Taraxacum officinalis Wigg. Huckleberry Vaccinium myrtillus L Blueberry Vaccinium uliginosum L Cranberry Vaccinium vitisidaea L and Stinging nettles Urtica dioica accordingly studied chemical composition and antioxidant activity and conducted pharmacological study. With the use of Folin Denis amp Folin Ciocalteu reagent methodit was determined that the content of polyphenol compounds was 4.14-5.17 and 27.5 101.5mgml. The study was also aimed to investigate DPPH free radical-scavenging activity in connection with term temperature and concentration to identify the most rational technological procedure. As a result of study it was identified that free radical-scavenging activity of herbs selected for the study was generally estimated at 564.25-1750.00 mcgml whereas antioxidant activity of solvents with 2-10 mgml concentration was 417.20-1750.00 mcg ml respectively. This shows that such activity is dependent on concentration. However in temperature of 30 1000amp1057 degrees their activity has slowly been decreased by 1750 mcgml 476.7mcgml depending on temperature. Regarding the stinging nettles the activity was grown directly dependent from temperature. DPHH free radical-scavenging activity was gradually increased in 1-10 minutes but was relatively stable and active in 11-16 minutes.

  20. An Experimental and Quantum Chemical Study of the Electronic Spectrum of the HBCl Free Radical

    Science.gov (United States)

    Gharaibeh, Mohammed A.; Nagarajan, Ramya; Clouthier, Dennis J.; Tarroni, Ricardo

    2012-06-01

    The chloroborane (HBCl) free radical has a complex electronic spectrum in the visible that involves a transition from a bent ground state to a linear excited state, both of which are the Renner-Teller components of what would be a ^2π state at linearity. We have used the synchronous-scan LIF and single vibronic level emission techniques to untangle the many overlapping vibronic bands and assign upper state K quantum numbers for jet-cooled HBCl and DBCl. The radicals were produced in a pulsed electric discharge jet using a precursor mixture of boron trichloride (BCl_3) and hydrogen or deuterium in high-pressure argon. As an important aid to understanding the data, the ground and excited state high level ab initio potential energy surfaces (PES) have been calculated and the vibrational levels obtained variationally. The calculated ground state levels are in excellent agreement with the emission data validating the quality of the PES. Aside from an approximately 100 cm-1 shift in the upper state electronic term value, the calculated excited state vibrational energy levels and isotope shifts match the LIF data very well, allowing the observed bands to be assigned with confidence.

  1. Detection of free radicals in γ-irradiated seasnail hard tissues by electron paramagnetic resonance

    International Nuclear Information System (INIS)

    Koeseoglu, Rahmi; Koeksal, Fevzi

    2003-01-01

    Gamma-irradiated seasnail (from family of Helix lukortium) hard tissues (CaCO 3 ) were investigated by electron paramagnetic resonance (EPR) at room temperature. The radicals produced by γ-irradiation in seasnail were attributed to orthorhombic C · O 2 - , freely rotating C · O 2 - , orthorhombic C · O 3 - , axial C · O 3 - , and axial C · O 3 3- free radicals. Unirradiated seasnail hard tissues also feature Mn 2+ ions in their EPR spectra. The hyperfine values were determined for the 13 C nucleus in the orthorhombic C · O 2 - and axial C · O 3 3- free radicals and for the manganese impurity ions. The g values of all the free radicals have been measured. The results were compared with the literature data for similar defects

  2. Increased cerebral output of free radicals during hypoxia: implications for acute mountain sickness?

    DEFF Research Database (Denmark)

    Bailey, Damian M; Taudorf, Sarah; Berg, Ronan M G

    2009-01-01

    This study examined whether hypoxia causes free radical-mediated disruption of the blood-brain barrier (BBB) and impaired cerebral oxidative metabolism and whether this has any bearing on neurological symptoms ascribed to acute mountain sickness (AMS). Ten men provided internal jugular vein...... paramagnetic resonance spectroscopy and ozone-based chemiluminescence were employed for direct detection of spin-trapped free radicals and nitric oxide metabolites. Neuron-specific enolase (NSE), S100beta, and 3-nitrotyrosine (3-NT) were determined by ELISA. Hypoxia increased the arterio-jugular venous...... concentration difference (a-v(D)) and net cerebral output of lipid-derived alkoxyl-alkyl free radicals and lipid hydroperoxides (P

  3. Reduction of cathodic delamination rates of anticorrosive coatings using free radical scavengers

    DEFF Research Database (Denmark)

    Sørensen, Per Aggerholm; Weinell, C. E.; Dam-Johansen, Kim

    2010-01-01

    Cathodic delamination is one of the major modes of failure for anticorrosive coatings subjected to a physical damage and immersed in seawater. The cause of cathodic delamination has been reported to be the result of a chemical attack at the coating-steel interface by free radicals and peroxides...... formed as intermediates in the cathodic reaction during the corrosion process. In this study, antioxidants (i.e., free radical scavengers and peroxide decomposers) have been incorporated into various generic types of coatings to investigate the effect of antioxidants on the rate of cathodic delamination...... of epoxy coatings on cold rolled steel. The addition of free radical scavengers to epoxy coatings improved the resistance toward cathodic delamination by up to 50% during seawater immersion, while peroxide decomposers had a limited effect. Testing using substrates prepared from stainless steel...

  4. Polyacrylamide grafting of modified graphene oxides by in situ free radical polymerization

    International Nuclear Information System (INIS)

    Tang, Mingyi; Xu, Xiaoyang; Wu, Tao; Zhang, Sai; Li, Xianxian; Li, Yi

    2014-01-01

    Highlights: • Graphene oxide (GO) was modified by chemical reactions to functionalized GO (FGO). • The FGOs and the GO were then subjected to in situ free radical polymerization. • Hydroxyl groups of GO were the most reactive grafting sites. - Abstract: Graphene oxide (GO) was modified using chemical reactions to obtain three types of functionalized GO sheets (FGO). The FGO sheets and the GO were then subjected to in situ free radical polymerization in order to study the grafting polymerization. The FGO and grafted-.FGO were analyzed with Fourier transform infrared spectroscopy, scanning electronic microscopy, thermo-gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The grafting percentages in the materials were calculated using the TGA and XPS results. The FGO sheets with different functional groups exhibited different grafting abilities, and hydroxyl groups were proven to be the most reactive grafting sites for the in situ free radical grafting polymerization of polyacrylamide

  5. Polyacrylamide grafting of modified graphene oxides by in situ free radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Mingyi [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Xu, Xiaoyang, E-mail: xiaoyangxu2012@163.com [School of Science, Tianjin University, Tianjin 30072 (China); Wu, Tao [School of Science, Tianjin University, Tianjin 30072 (China); Zhang, Sai; Li, Xianxian [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Li, Yi, E-mail: liyi@tju.edu.cn [School of Science, Tianjin University, Tianjin 30072 (China)

    2014-12-15

    Highlights: • Graphene oxide (GO) was modified by chemical reactions to functionalized GO (FGO). • The FGOs and the GO were then subjected to in situ free radical polymerization. • Hydroxyl groups of GO were the most reactive grafting sites. - Abstract: Graphene oxide (GO) was modified using chemical reactions to obtain three types of functionalized GO sheets (FGO). The FGO sheets and the GO were then subjected to in situ free radical polymerization in order to study the grafting polymerization. The FGO and grafted-.FGO were analyzed with Fourier transform infrared spectroscopy, scanning electronic microscopy, thermo-gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The grafting percentages in the materials were calculated using the TGA and XPS results. The FGO sheets with different functional groups exhibited different grafting abilities, and hydroxyl groups were proven to be the most reactive grafting sites for the in situ free radical grafting polymerization of polyacrylamide.

  6. Free radicals and antioxidants in primary fibromyalgia: an oxidative stress disorder?

    Science.gov (United States)

    Bagis, Selda; Tamer, Lulufer; Sahin, Gunsah; Bilgin, Ramazan; Guler, Hayal; Ercan, Bahadir; Erdogan, Canan

    2005-04-01

    The role of free radicals in fibromyalgia is controversial. In this study, 85 female patients with primary fibromyalgia and 80 age-, height-, and weight-matched healthy women were evaluated for oxidant/antioxidant balance. Malondialdehyde is a toxic metabolite of lipid peroxidation used as a marker of free radical damage. Superoxide dismutase is an intracellular antioxidant enzyme and shows antioxidant capacity. Pain was assessed by visual analog scale. Tender points were assessed by palpation. Age, smoking, body mass index (BMI), and duration of disease were also recorded. Malondialdehyde levels were significantly higher and superoxide dismutase levels significantly lower in fibromyalgic patients than controls. Age, BMI, smoking, and duration of disease did not affect these parameters. We found no correlation between pain and number of tender points. In conclusion, oxidant/antioxidant balances were changed in fibromyalgia. Increased free radical levels may be responsible for the development of fibromyalgia. These findings may support the hypothesis of fibromyalgia as an oxidative disorder.

  7. Effect of ultraviolet irradiation on free radical scavenging activity of immunosuppressants used in lung transplantation and comparative electron paramagnetic resonance study of kinetics of their interactions with model free radicals.

    Science.gov (United States)

    Stanjek-Cichoracka, A; Żegleń, S; Ramos, P; Pilawa, B; Wojarski, J

    2018-06-01

    The immunosuppressive drugs used in solid organ transplantation or autoimmunological processes were studied by electron paramagnetic resonance (EPR) spectroscopy to estimate their free radical scavenging activity. The interactions of immunosuppressants with free radicals were examined by an X-band (9.3 GHz) EPR spectroscopy and a model of DPPH free radicals. The EPR spectra of DPPH and DPPH interacting with individual drugs were compared. Kinetic studies were performed, and the effect of ultraviolet (UV) irradiation on the free radical scavenging activity of the tested drugs was determined. The free radical scavenging activity of non-irradiated drugs decreased in the order: rapamycin > mycophenolate mofetil > ciclosporin > tacrolimus. UV irradiation increased the free radical scavenging activity of all the tested immunosuppressive drugs, and the effect was highest for tacrolimus. For the non-irradiated samples, the speed of free radical interactions decreased in the order: ciclosporin > tacrolimus > mycophenolate mofetil > rapamycin. UV irradiation only slightly affected the speed of interactions of the immunosuppressive drugs with the model DPPH free radicals. Electron paramagnetic resonance spectroscopy is useful for obtaining information on interactions of immunosuppressive drugs with free radicals. We hypothesized that the long-term immunosuppressive effects of these drugs after transplantation or during autoimmune disorders may be mediated by anti-inflammatory action in addition to the known receptor/cell cycle inhibition. © 2018 John Wiley & Sons Ltd.

  8. Free Radicals Formation of Irradiated Lyophilized Can-Cellous Human and Bovine Bone

    International Nuclear Information System (INIS)

    Abbas, Basril; Sudiro, Sutjipto; Hilmy, Nazly

    2000-01-01

    Radiation sterilization of lyophilized human and bovine bone as allograft and xenograft have been produced and used in orthopaedic practice in Indonesia routinely. It is well known from radio biologic studies that one of the most pronounce effects of ionizing radiation on biologic species produced the free radicals that influence the physico-chemical as well as the mechanical properties of irradiated bone. The aim of our study is to investigate the free radicals formation of irradiated lyophilized cancellous triple A bone (Autolyzed Antigen-Extracted Allograft) produced by Batan Research Tissue Bank in Jakarta. The cancellous triple A were prepared according to AATB (American Association of Tissue Bank) method. Gamma Irradiations was done at doses of 10, 20 and 30 kGy with a dose rate of 7,5 kGy/h at room temperature (30 o C± 2 o C). Measurements of free radicals was done at 24 o C ±1 o C within 30 minutes after irradiational and measurement were continued up to 9 months of storage using a JES-REIX ESR Spectrophotometer (JEOL) with Mn exp. ++ standard. Parameters measured, were the effects of mechanical grinding, water immersion and irradiation dose on free radicals formation in the bone. Results show that the signal area of ESR spectra from irradiated bovine bone of 30 kGy was higher than those of human bone I.e. 1,4 x 10 exp. 7 dan 6,4 x 10 exp. 6 Au (arbitrary unit)/g samples respectively. The signal of ESR spectra increased linearly with increasing dose in the range of 10-30 kGy and it will reduce about 30% caused by water immersion. The ESR signal reduced sharply after 2 days and gradually decreased up to 14 days and then became constant up to 9 months of storage at room temperature. A certain method of crushing can produce free radicals. Key Words: free radical, irradiation, allograft, xenograft, mechanical-grinding

  9. Toward unfolding the prion misfolding mystery: protein free radical chemistry in transmissible spongiform encephalopathies

    International Nuclear Information System (INIS)

    Yang Chiming

    2003-01-01

    Owing to the high oxygen-respiration in the brain of mammals, oxidative damage to prion protein has been suggested to be an additional factor. A large body of intriguing features of scrapie and prion diseases have provided multiple lines of indirect chemistry evidence, suggesting that the infectious agents may be putative forms of sequence-specific prion radicals (SSPR) and/or their immediate precursors in the transmissible spongiform encephalopathies (TSE). Here a molecular mechanism corresponding to the self-replication of scrapie protein mediated by prion free-radical processes, consonant with 'protein-only' hypotheses is proposed. This new theory may not only aid our understanding of the occurrence of prions, but also provides new insight into the possible chemistry principles underlying the neutrodegenerative disorders. It is anticipated that future studies based on this suggestion and chemistry principles of genetic diseases may allow us to determine an effective approach to stop mad cow disease and its human version, new variant of Creutzfeldt-Jakob disease (v CJD)

  10. Free radicals from irradiated lyophilized DNA: influence of water of hydration

    International Nuclear Information System (INIS)

    Huettermann, J.; Roehrig, M.; Koehnlein, W.

    1992-01-01

    Lyophilized DNA equilibrated with water vapour at various relative humidities (0-95% H 2 O or D 2 O) was X-irradiated at 77 K and analysed for free radicals by electron paramagnetic resonance (EPR) spectroscopy in the temperature range 77-280 K. Analysis of spectra according to variation in humidity, microwave power and temperature generally yielded a doublet and a triplet spectrum at 77 K. The doublet partially converted into the 5-thymyl radical (TH . ). DNA containing deuterated thymine (dTDNA) revealed that the doublet of ''normal'' DNA should be composed of two similar doublets, one of which should be assigned to the thymine anion, the other possibly the cytosine anion. The triplet signal was more stable and could be related to the guanine cation or its deprotonated successor. Several other patterns were detected among them an allyl radical in highly aquated DNA (95% humidity). Other features occurred either predominantly or exclusively in DNA equilibrated above 66% relative humidity and were ascribed to an influence of the secondary structure. (author)

  11. Influence of the irradiation temperature on the free-radical response of alanine

    International Nuclear Information System (INIS)

    Wieser, A.; Siegele, R.; Regulla, D.F.

    1989-01-01

    GSF operates the only IAEA high-level dosimetry reference laboratory and, as a joint project with the IAEA, the International Dose Assurance Service (IDAS). Dosimetry is based on long-lived free radicals in organic alanine induced by ionizing radiation and readout by ESR spectroscopy. The thermal time response of the radical concentration in alanine is fairly constant after irradiation provided that the alanine samples are stored at temperatures below 50 0 C. By contrast, a positive temperature coefficient had earlier been found at GSF for the production rate of alanine radicals, for irradiation temperatures between 0 and 50 0 C. This effect has to be considered for reference dosimetry in radiation processing. Radiation processing is also of interest at irradiation temperatures below 0 0 C. The present study describes experiments on the influence of irradiation temperatures between +50 and -100 0 C. Comparison is made between the present and earlier results, in the overlapping temperature range. An empirical function is proposed for the temperature coefficient based on the experimental data. (author)

  12. Intracellular ROS protection efficiency and free radical-scavenging activity of curcumin.

    Directory of Open Access Journals (Sweden)

    Abolfazl Barzegar

    Full Text Available Curcumin has many pharmaceutical applications, many of which arise from its potent antioxidant properties. The present research examined the antioxidant activities of curcumin in polar solvents by a comparative study using ESR, reduction of ferric iron in aqueous medium and intracellular ROS/toxicity assays. ESR data indicated that the steric hindrance among adjacent big size groups within a galvinoxyl molecule limited the curcumin to scavenge galvinoxyl radicals effectively, while curcumin showed a powerful capacity for scavenging intracellular smaller oxidative molecules such as H₂O₂, HO•, ROO•. Cell viability and ROS assays demonstrated that curcumin was able to penetrate into the polar medium inside the cells and to protect them against the highly toxic and lethal effects of cumene hydroperoxide. Curcumin also showed good electron-transfer capability, with greater activity than trolox in aqueous solution. Curcumin can readily transfer electron or easily donate H-atom from two phenolic sites to scavenge free radicals. The excellent electron transfer capability of curcumin is because of its unique structure and different functional groups, including a β-diketone and several π electrons that have the capacity to conjugate between two phenyl rings. Therfore, since curcumin is inherently a lipophilic compound, because of its superb intracellular ROS scavenging activity, it can be used as an effective antioxidant for ROS protection within the polar cytoplasm.

  13. [The relationship between neuroendocrine dysfunction and free-radical oxidation in old age alcoholism].

    Science.gov (United States)

    Vinogradov, D B; Mingazov, A Kh; Izarovskaya, I V; Babin, K A; Sinitsky, A I

    2015-01-01

    to study the relationship between dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis and free-radical oxidation in old age alcoholism. Authors examined 46 men and women, aged 60-80 years, with alcoholism. Contents of cortisol, lipid peroxidation products and the level of an oxidatively modified protein were measured. A decrease in blood cortisol content and correlations between its level and activity of free-radical oxidation were identified. The severity of neuroendocrine dysfunction in old patients was sex-related. It has been suggested that the impairment of HPA system activity may be a cause of oxidative stress and development of alcoholism.

  14. Phenolic profile and free radical-scavenging activity of Cabernet Sauvignon wines of different geographical origins from the Balkan region.

    Science.gov (United States)

    Radovanović, Blaga C; Radovanović, Aleksandra N; Souquet, Jean-Marc

    2010-11-01

    The phenolic profile, determined by the relative proportions of different phenolic compounds, is characteristic for each grape variety and its corresponding wine. The aim of this study was to determine the phenolic and hydroxycinnamate acid, flavan-3-ol and flavonol contents and free radical-scavenging activity of single-cultivar (Cabernet Sauvignon) wines from selected Balkan vineyard regions by spectrophotometric methods and high-performance liquid chromatography with photodiode array and fluorescence detection. The contents of phenolic compounds varied depending on the agroclimatic factors and oenological practices of the vineyard region. The antioxidant activity of wine samples was estimated by their ability to scavenge the stable 2,2'-diphenyl-1-picrylhydrazyl free radical (DPPH). All wines showed high DPPH-scavenging activity (70.03-83.53%, mean 73.76%). Significant correlations between catechin (R(2) = 0.8504) and quercetin (R(2) = 0.8488) concentrations and DPPH-scavenging ability of the wines were found. The concentrations of the main components catechin and quercetin can be used as biochemical markers for the authentication of red grape cultivars and their corresponding single-cultivar wines. 2010 Society of Chemical Industry

  15. Studies of free radicals by ultraviolet excimer laser photolysis. Progress report, 1 April 1980-1 November 1980

    International Nuclear Information System (INIS)

    Leone, S.R.

    1980-01-01

    An experimental technique has been developed to produce and directly study vibrationally excited free radicals. Pulses of light from an ultraviolet excimer laser are used to photodissociate small molecules to generate free radicals with high internal excitation. The radicals are detected directly by the technique of time and wavelength-resolved infrared emission spectroscopy using a background-limited copper-doped germanium infrared detector. New results have been obtained on the CH 3 radical. A complete spectrum of the CH 3 umbrella band reveals for the first time accurate positions of the vibrational progression in this band. Photofragmentation of (CH 3 ) 2 Hg has yielded detailed information on the vibrational distribution, rotational temperature, and deactivation rates of the CH 3 stretch mode. A technique to study chemical chain reactions using low power, radical-specific, laser initiation and realtime kinetics detection had previously been demonstrated. The results provide a general method to study a large number of chain reaction combustion systems in greater detail. New results on more complex chain reactions such as Cl 2 /butane reveal that highly detailed infrared emission spectra of various products of the chain and their time evolution is possible. Partitioning of energy between vibrational degrees of freedom and translational heating is obtained over the course of the combustion

  16. Free radicals imaged in vivo in the rat by using proton-electron double-resonance imaging

    International Nuclear Information System (INIS)

    Lurie, D.J.; Nicholson, Ian; Foster, M.A.; Mallard, J.R.

    1990-01-01

    A new technique called proton-electron double-resonance imaging is described for imaging free radicals in aqueous samples. The method is a combination of proton NMR imaging with nuclear electron double resonance. The results of using this technique to image free radicals in vivo in the rat are presented. Rats were injected intravenously with a nitroxide free radical solution and a series of images was obtained from which the clearance of the free radical through the liver and kidneys could be observed. (author)

  17. Catalase expression is modulated by vancomycin and ciprofloxacin and influences the formation of free radicals in Staphylococcus aureus cultures

    DEFF Research Database (Denmark)

    Wang, Ying; Hougaard, Anni Bygvrå; Paulander, Wilhelm Erik Axel

    2015-01-01

    Detection of free radicals in biological systems is challenging due to their short half-lives. We have applied electron spin resonance (ESR) spectroscopy combined with spin traps using the probes PBN (N-tert-butyl-α-phenylnitrone) and DMPO (5,5-dimethyl-1-pyrroline N-oxide) to assess free radical...... that in S. aureus, bactericidal antibiotics modulate catalase expression, which in turn influences the formation of free radicals in the surrounding broth medium. If similar regulation is found in other bacterial species, it might explain why bactericidal antibiotics are perceived as inducing formation...... of free radicals....

  18. High Energy Density Laboratory Astrophysics

    CERN Document Server

    Lebedev, Sergey V

    2007-01-01

    During the past decade, research teams around the world have developed astrophysics-relevant research utilizing high energy-density facilities such as intense lasers and z-pinches. Every two years, at the International conference on High Energy Density Laboratory Astrophysics, scientists interested in this emerging field discuss the progress in topics covering: - Stellar evolution, stellar envelopes, opacities, radiation transport - Planetary Interiors, high-pressure EOS, dense plasma atomic physics - Supernovae, gamma-ray bursts, exploding systems, strong shocks, turbulent mixing - Supernova remnants, shock processing, radiative shocks - Astrophysical jets, high-Mach-number flows, magnetized radiative jets, magnetic reconnection - Compact object accretion disks, x-ray photoionized plasmas - Ultrastrong fields, particle acceleration, collisionless shocks. These proceedings cover many of the invited and contributed papers presented at the 6th International Conference on High Energy Density Laboratory Astrophys...

  19. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    International Nuclear Information System (INIS)

    Tanaka, Hiromasa; Mizuno, Masaaki; Toyokuni, Shinya; Maruyama, Shoichi; Kodera, Yasuhiro; Terasaki, Hiroko; Adachi, Tetsuo; Kato, Masashi; Kikkawa, Fumitaka; Hori, Masaru

    2015-01-01

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established

  20. Cancer therapy using non-thermal atmospheric pressure plasma with ultra-high electron density

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Hiromasa [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Mizuno, Masaaki [Center for Advanced Medicine and Clinical Research, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Toyokuni, Shinya [Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Maruyama, Shoichi [Department of Nephrology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kodera, Yasuhiro [Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Terasaki, Hiroko [Department of Ophthalmology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Adachi, Tetsuo [Laboratory of Clinical Pharmaceutics, Gifu Pharmaceutical University, 501-1196 Gifu (Japan); Kato, Masashi [Department of Occupational and Environmental Health, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Kikkawa, Fumitaka [Department of Obstetrics and Gynecology, Nagoya University Graduate School of Medicine, Tsurumai-cho 65, Showa-ku, Nagoya 466-8550 (Japan); Hori, Masaru [Institute of Innovation for Future Society, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-12-15

    Cancer therapy using non-thermal atmospheric pressure plasma is a big challenge in plasma medicine. Reactive species generated from plasma are key factors for treating cancer cells, and thus, non-thermal atmospheric pressure plasma with high electron density has been developed and applied for cancer treatment. Various cancer cell lines have been treated with plasma, and non-thermal atmospheric plasma clearly has anti-tumor effects. Recent innovative studies suggest that plasma can both directly and indirectly affect cells and tissues, and this observation has widened the range of applications. Thus, cancer therapy using non-thermal atmospheric pressure plasma is promising. Animal experiments and understanding the mode of action are essential for clinical application in the future. A new academic field that combines plasma science, the biology of free radicals, and systems biology will be established.

  1. The free radical scavenger, edaravone, ameliorates delayed neuropsychological sequelae after acute carbon monoxide poisoning in rabbits.

    Science.gov (United States)

    Qingsong, Wang; Yeming, Guan; Xuechun, Liu; Hongjuan, Liu; Jing, Wang

    2013-01-01

    The mechanism underlying delayed neuropsychological sequelae (DNS) after acute carbon monoxide (CO) poisoning is unclear. There are no effective treatments for DNS. As part of a new generation of antioxidants, edaravone has been reported to improve clinical outcomes in patients exhibiting ischemic strokes. There has been little data about edaravone in relationship to DNS prevention and treatment. We hypothesized that edaravone could ameliorate DNS: Here we test that hypothesis in rabbits Rabbits were randomly divided into sham control,DNS group, saline group and edaravone group. DNS model was made by intraperitoneal injection of CO. Normal saline or edaravone (1 mg/kg, twice daily, a total of one course for 14 days) was infused through the ear vein from Day 15 since the DNS model was established. Serum superoxide dismutase (SOD) activity and malondialdehyde (MDA) were measured in each group. Magnetic resonance spectroscopy (MRS) was used to examine regions of the brain for various compounds. The apoptotic index and neuronal density in the hippocampal CA1 area were also investigated. SOD activity decreased significantly and MDA content increased substantially in the DNS group and saline group when compared with the sham control (p edaravone group, serum SOD activity significantly increased and MDA levels significantly decreased when compared with DNS and saline group (p edaravone group (p edaravone group was significantly lower than that of the DNS and saline groups (p edaravone group was significantly higher than that of the DNS and saline group in the hippocampal CA1 area (p edaravone could ameliorate DNS after acute carbon monoxide poisoning in rabbits. These results suggest free radicals could be involved in the underlying mechanisms of DNS. Furthermore, brain MRS shows promise as a tool for early diagnosis for DNS.

  2. Novel Water Soluble Chitosan Derivatives with 1,2,3-Triazolium and Their Free Radical-Scavenging Activity

    Directory of Open Access Journals (Sweden)

    Qing Li

    2018-03-01

    Full Text Available Chitosan is an abundant and renewable polysaccharide, which exhibits attractive bioactivities and natural properties. Improvement such as chemical modification of chitosan is often performed for its potential of providing high bioactivity and good water solubility. A new class of chitosan derivatives possessing 1,2,3-triazolium charged units by associating “click reaction” with efficient 1,2,3-triazole quaternization were designed and synthesized. Their free radical-scavenging activity against three free radicals was tested. The inhibitory property and water solubility of the synthesized chitosan derivatives exhibited a remarkable improvement over chitosan. It is hypothesized that triazole or triazolium groups enable the synthesized chitosan to possess obviously better radical-scavenging activity. Moreover, the scavenging activity against superoxide radical of chitosan derivatives with triazolium (IC50 < 0.01 mg mL−1 was more efficient than that of derivatives with triazole and Vitamin C. In the 1,1-diphenyl-2-picrylhydrazyl (DPPH and hydroxyl radical-scavenging assay, the same pattern were observed, which should be related to the triazolium grafted at the periphery of molecular chains.

  3. Ethylene formation from methionine as a method to evaluate oxygen free radical scavenging and metal inactivation by cosmetics.

    Science.gov (United States)

    Galey, J B; Millecamps, F; Nguyen, Q L

    1991-04-01

    Synopsis It has been proposed that oxygen free radicals are involved in skin aging. This paper describes a new method for the evaluation of oxygen free radical scavenging by cosmetic products. It is based on the measurement, by gas chromatography, of ethylene produced during the oxidation of methionine by the hydroxyl radical. OH. is produced by an iron catalyzed superoxide-driven Fenton reaction in which superoxide is obtained by photochemical oxygen reduction. The cosmetic is applied, together with methionine, riboflavine, NADH, FeCl(3) and EDTA, on a glass microfibre filter and submitted to UVA exposure through a quartz cell. Ethylene is then measured from aliquots of the atmosphere inside the cell. Catalase or Desferal completely inhibits ethylene production. SOD or high concentrations of hydroxyl radical scavengers (Mannitol, DMSO etc.) afford a partial protection. Thus the efficiency of O(2) (-)., H(2)O(2) and OH. scavengers and iron chelators can be measured. The main advantage of this test is that it is performed in conditions which simulate skin during UV exposure (e.g. air and UV exposed thin layer). Furthermore, as it is non-invasive, it can also be applied to human skin in vivo.

  4. Free radical scavenging activities measured by electron spin resonance spectroscopy and B16 cell antiproliferative behaviors of seven plants.

    Science.gov (United States)

    Calliste, C A; Trouillas, P; Allais, D P; Simon, A; Duroux, J L

    2001-07-01

    In an effort to discover new antioxidant natural compounds, seven plants that grow in France (most of them in the Limousin countryside) were screened. Among these plants, was the extensively studied Vitis vinifera as reference. For each plant, sequential percolation was realized with five solvents of increasing polarities (hexane, chloroform, ethyl acetate, methanol, and water). Free radical scavenging activities were examined in different systems using electron spin resonance (ESR) spectroscopy. These assays were based on the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH), the hydroxyl radicals generated by a Fenton reaction, and the superoxide radicals generated by the X/XO system. Antiproliferative behavior was studied on B16 melanoma cells. ESR results showed that three plants (Castanea sativa, Filipendula ulmaria, and Betula pendula) possessed, for the most polar fractions (presence of phenolic compounds), high antioxidant activities in comparison with the Vitis vinifera reference. Gentiana lutea was the only one that presented a hydroxyl scavenging activity for the ethyl acetate and chloroform fractions. The antiproliferative test results showed that the same three plants are the most effective, but for the apolar fractions (chloroform and hexane).

  5. Prooxidant/Antioxidant Ratio (ProAntidex as a Better Index of Net Free Radical Scavenging Potential

    Directory of Open Access Journals (Sweden)

    Hwee Ming Cheng

    2010-11-01

    Full Text Available The antioxidant activity of several Malaysian plant extracts was analyzed simultaneously with their pro-oxidant capacity. This ratio represents an index (ProAntidex of the net free radical scavenging ability of whole plant extracts. We observed that ethanolic extracts of Nephelium lappaceum peel, Fragaria x ananassa leaf, Lawsonia inermis leaf, Syzygium aqueum leaf and grape seed had a lower Pro-Antidex than the commercially available Emblica™ extract which is an antioxidant agent with very low pro-oxidant activity. Among the aqueous extracts, Lawsonia inermis leaf, Nephelium mutobile leaf and grape seed had lower pro-oxidant activity compared to the Emblica™ extract. Among these extracts, aqueous extract of Nephelium mutobile leaf had a very low index of 0.05 compared to 0.69 for Emblica™. Most of the extracts had a far lower ProAntidex compared to the Vitamin C. The index enables us to identify extracts with high net free radical scavenging activity potential. The ProAntidex is beneficial as a screening parameter to the food industries and healthcare.

  6. Evaluation of antitumor, immunomodulatory and free radical scavenging effects of a new herbal prescription seaweed complex preparation

    Science.gov (United States)

    Liu, Xin; Shao, Changlun; Kong, Wenwen; Fang, Yuchun; Wang, Changyun

    2013-09-01

    Seaweed Complex Preparation (SCP) is a clinical traditional Chinese medicine preparation which is composed of seven traditional Chinese herbs, and it has been used for treatment of lung cancer, liver cancer and digestive cancer. However, little information is available about the pharmacodynamic basis. The antitumor, immunomodulatory and free radical scavenging effects of SCP were evaluated in this study. Transplanted tumor in vivo method was used to determine the antitumor effect. The effects on splenocyte proliferation and phagocytosis of macrophages in tumor-bearing mice were measured by the MTT method and the phagocytizing cock red blood cell (CRBC) method respectively. The scavenging activities of SCP on DPPH and hydroxyl radicals in vitro were investigated. It was found that the medium-dose and high-dose of SCP could significantly inhibit the growth of transplanted hepatic tumor of murine hepatocarcinoma cell line H22, and promote proliferation of splenocytes and phagocytosis of macrophages. SCP possessed noticeable scavenging activities on DPPH and hydroxyl radicals. The antitumor effects of SCP might be achieved by improving immune system and scavenging free radicals, which is in accordance with the viewpoint of traditional Chinese medicine in promoting the body resistance and eliminating pathogenic factors for cancer treatment.

  7. High current density ion source

    International Nuclear Information System (INIS)

    King, H.J.

    1977-01-01

    A high-current-density ion source with high total current is achieved by individually directing the beamlets from an electron bombardment ion source through screen and accelerator electrodes. The openings in these screen and accelerator electrodes are oriented and positioned to direct the individual beamlets substantially toward a focus point. 3 figures, 1 table

  8. formation and behaviour of coal free radicals in relation to ...

    African Journals Online (AJOL)

    DJFLEX

    61, 1249 – 1253. Xu L., Yang J and liu Z., 2004. Behaviour of organic sulfur model compounds in pyrolysis under coal like environment. Fuel Processing Technology 85 (8 - 10),. 1013 - 1024. Yokono T. Iyama S. Sanada Y. Shimokawa S and Yamada E., 1986. High temperature and high pressure 1H nmr and esr studies on.

  9. Anxiolytic and free radical scavenging potential of Chinese celery (Apium graveolens extract in mice

    Directory of Open Access Journals (Sweden)

    Supita Tanasawet

    2017-01-01

    Conclusions: Taken together, we showed that A. graveolens improve the behavioral changes which might be related to the inhibition of free radicals and modulation of MAO-A activity resulting in an increased number of survival neurons. Our findings suggest the therapeutic potential of A. graveolens in the treatment of anxiety.

  10. Investigations of the inhibitory effects of tocopherol (vitamin E) on free radical deterioration of cellular membranes

    Science.gov (United States)

    Richardson, D.

    1975-01-01

    The inhibitory effects are investigated of d,1-alpha-tocopherol and d,1-alpha-tocopheryl acetate on the free radical deterioration of cellular membranes. The level of toxicity of d,1-alpha-tocopherol and d,1-alpha-tocopheryl acetate in mice is determined.

  11. IN VIVO EVIDENCE OF FREE RADICAL FORMATION AFTER ASBESTOS INSTILLATION: AN ESR SPIN TRAPPING INVESTIGATION

    Science.gov (United States)

    It has been postulated that the in vivo toxicity of asbestos results from its catalysis of free radical generation. We examined in vivo radical production using electron spin resonance (ESR) coupled with the spin trap alpha-(4-pyridyl-1-oxide)-N-t-butylnitrone (4-POBN); 180 d...

  12. Computational studies of free radical-scavenging properties of phenolic compounds.

    Science.gov (United States)

    Alov, Petko; Tsakovska, Ivanka; Pajeva, Ilza

    2015-01-01

    For more than half a century free radical-induced alterations at cellular and organ levels have been investigated as a probable underlying mechanism of a number of adverse health conditions. Consequently, significant research efforts have been spent for discovering more effective and potent antioxidants / free radical scavengers for treatment of these adverse conditions. Being by far the most used antioxidants among natural and synthetic compounds, mono- and polyphenols have been the focus of both experimental and computational research on mechanisms of free radical scavenging. Quantum chemical studies have provided a significant amount of data on mechanisms of reactions between phenolic compounds and free radicals outlining a number of properties with a key role for the radical scavenging activity and capacity of phenolics. The obtained quantum chemical parameters together with other molecular descriptors have been used in quantitative structure-activity relationship (QSAR) analyses for the design of new more effective phenolic antioxidants and for identification of the most useful natural antioxidant phenolics. This review aims at presenting the state of the art in quantum chemical and QSAR studies of phenolic antioxidants and at analysing the trends observed in the field in the last decade.

  13. Lipid-derived free radical production in superantigen-induced interstitial pneumonia

    Science.gov (United States)

    Miyakawa, Hisako; Mason, Ronald P.; Jiang, JinJie; Kadiiska, Maria B.

    2009-01-01

    We studied the free radical generation involved in the development of interstitial pneumonia (IP) in an animal model of autoimmune disease. We observed an electron spin resonance (ESR) spectrum of α-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN) radical adducts detected in the lipid extract of lungs in autoimmune-prone mice after intratracheal instillation of staphylococcal enterotoxin B. The POBN adducts detected by ESR were paralleled by infiltration of macrophages and neutrophils in the bronchoalveolar lavage fluid. To further investigate the mechanism of free radical generation, mice were pretreated with the macrophage toxicant gadolinium chloride, which significantly suppressed the radical generation. Free radical generation was also decreased by pretreatment with the xanthine oxidase (XO) inhibitor allopurinol, the iron chelator Desferal, and the inducible nitric oxide synthase (iNOS) inhibitor 1400W. Histopathologically, these drugs significantly reduced both the cell infiltration to alveolar septal walls and the synthesis of pulmonary collagen fibers. Experiments with NADPH oxidase knockout mice showed that NADPH oxidase did not contribute to lipid radical generation. These results suggest that lipid-derived carbon-centered free radical production is important in the manifestation of IP and that a macrophage toxicant, an XO inhibitor, an iron chelator, and an iNOS inhibitor protect against both radical generation and the manifestation of IP. PMID:19376221

  14. Effects of Ginkgo biloba extract on free radical metabolism of liver in ...

    African Journals Online (AJOL)

    This study investigated the effect of Ginkgo biloba extract on Free Radical Metabolism of Liver in mice during endurance exercise. Forty-eight mice were divided into the quiet group and the exercised group. And the two groups were both grouped again, including the control group and the drug-treated group.

  15. Induction of oxygen free radical generation in human monocytes by lipoprotein(a)

    DEFF Research Database (Denmark)

    Riis Hansen, P; Kharazmi, A; Jauhiainen, M

    1994-01-01

    The mechanism behind the association of elevated plasma lipoprotein(a) [Lp(a)] levels with atherosclerotic disease is unknown. In the present study, Lp(a) induced generation of oxygen free radicals by monocytes from selected healthy individuals in vitro. This observation may provide a link between...

  16. Preparation of polystyrene-poly(ethylene glycol) diblock copolymer by "living" free radical polymerization

    DEFF Research Database (Denmark)

    Chen, Xianyi; Gao, Bo; Kops, Jørgen

    1998-01-01

    terminated with a TEMPO unit (MPEG-TEMPO), which was further used to prepare the diblock copolymer PS-b-PEG by 'living' free radical polymerisation of styrene. The product was purified and identified by H-1 n.m.r. and GPC. However, large amounts of homopolystyrene was also formed by simultaneous thermal...

  17. Crystal lattice dependency of the free radicals found in irradiated glycine

    NARCIS (Netherlands)

    Bie, M.J.A. de; Braams, R.

    1969-01-01

    The EPR spectra, and hence the stable free radicals, are different for the - or γ-irradiated α-, β- and γ-crystal forms of polycrystalline glycone. Therefore comparisons of the trideutero-glycine EPR spectrum with the EPR spectra of non-deuterated glycine are open to question

  18. Free radicals in hypoxic rat diaphragm contractility: no role for xanthine oxidase.

    NARCIS (Netherlands)

    Heunks, L.M.A.; Machiels, H.A.; Abreu, R.A. de; Zhu, X.; Heijden, E. van der; Dekhuijzen, P.N.R.

    2001-01-01

    Recent evidence indicates that hypoxia enhances the generation of oxidants. Little is known about the role of free radicals in contractility of the rat diaphragm during hypoxia. We hypothesized that antioxidants improve contractility of the hypoxic rat diaphragm and that xanthine oxidase (XO) is an

  19. DPPH and oxygen free radicals as pro-oxidant of biomolecules.

    Science.gov (United States)

    Letelier, María Eugenia; Molina-Berríos, Alfredo; Cortés-Troncoso, Juan; Jara-Sandoval, José; Holst, Marianne; Palma, Karina; Montoya, Margarita; Miranda, Dante; González-Lira, Víctor

    2008-03-01

    Numerous investigations exist about the alterations that oxygen free radicals can provoke on biomolecules; these modifications can be prevented and/or reversed by different antioxidants agents. On the other hand, 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), a stable nitrogen synthetic radical, is used to evaluate the antioxidant capacity of medicinal herbal products; however, the structural changes that this radical provoke on the herbal active principles are not clear yet. In this work, we compared the redox reactivity of oxygen free radicals and DPPH radical on phospholipids and protein thiol groups present in rat liver microsomes. Cu2+/ascorbate was used as generator system of oxygen free radical and as antioxidant, an extract of Buddleja globosa's leaves. Cu2+/ascorbate provoked microsomal lipid peroxidation, microsomal thiols oxidation and oxygen consumption; all of these phenomena were inhibited by B. globosa extract. On the other hand, DPPH was bleached in different extension by the herbal extract and phosphatidyl choline; beside, DPPH decreased microsomal thiols content, but this phenomenon were not prevented by the herbal extract. Furthermore, DPPH did not induce oxygen consumption and neither modified the oxygen consumption induced by Cu2+/ascorbate. Distinct redox mechanisms may explain the differences between the reactivity of DPPH and oxygen free radicals on biomolecules, which is discussed.

  20. Role of oxygen free radicals in the induction of sister chromatid exchanges by cigarette smoke

    International Nuclear Information System (INIS)

    Lee, C.K.; Brown, B.G.; Rice, W.Y. Jr.; Doolittle, D.J.

    1989-01-01

    Cigarette smoke has been reported to contain free radicals and free radical generators in both the gas and particulate phases. Studies in our laboratory have shown that both cigarette smoke condensate (CSC) and smoke bubbled through phosphate buffered saline solution (smoke-PBS) increased sister chromatid exchanges (SCE) in Chinese hamster ovary cells in a dose-dependent manner. Since oxygen free radicals have been shown to cause SCEs and other chromosomal damage, we investigated the role of these radicals in the induction of SCEs by CSC and smoke-PBS. Addition of the antioxidant enzymes catalase and superoxide dismutase or the oxygen-radical scavenger ascorbic acid failed to reduce the SCE frequency in the presence of either CSC or smoke-PBS. Additional studies indicated that the quantity of hydrogen peroxide produced in CSC or smoke-PBS is too small to account for the observed SCE induction. It appears, therefore, that SCE induction by CSC or smoke-PBS does not involve the participation of oxygen free radicals

  1. Notes on free radicals in the field of human and environmental protection against ionizing radiations

    International Nuclear Information System (INIS)

    Bittel, R.

    It is well known that ionizing radiations, in vitro and in vivo produce, free radicals which may be considered as mediators between physical agents and biological targets. Some aspects of this vast problem are accentuated. Ionizing radiations act either directly on the organic molecules of tissues or indirectly by creating, in the surroundings and in tissular water, inorganic free radicals which act on biochemical molecules to gives new radicals. Analysis of the free radical initiation phenomenon in vivo shows that many initiating agents exist, ionizing radiations representing only one group. The role of oxydants, especially oxydising polluants, and the part played by various enzyme systems (super-oxide dismutase, oxydases etc...) are emphasized. After propagation the chain reactions end in combinations between radicals are stopped by certain organic molecules (radical scavengers). Examples are given (free radical formation from compounds of great biological importance: puric and pyrimidic bases, nucleic acids in particular). These aspects are discussed from the viewpoint of their effects on human and environmental protection against both ionizing radiations and certain chemical pollution [fr

  2. Synthesis of tetrahydrokhusitone. Annulation of the cyclohexane ring by free radical and carbanionic sequence of reactions

    Directory of Open Access Journals (Sweden)

    ZIVORAD CEKOVIC

    2003-05-01

    Full Text Available The synthesis of norcadinane sesquiterpene tetrahydrokhusitone 1 has been achieved by a new method for annulation of cyclohexane ring involving a sequence of free radical d-alkylation of the non-activated carbon atom and intramolecular carbanionic alkylation. (–-Menthol was used as the starting compound.

  3. Critically evaluated rate coefficients for free-radical polymerization, 5. Propagation rate coefficient for butyl acrylate

    NARCIS (Netherlands)

    Asua, J.M.; Beuermann, S.; Buback, M.; Castignolles, P.; Charleux, B.; Gilbert, R.G.; Hutchinson, R.A.; Leiza, J.R.; Nikitin, A.N.; Vairon, J.P.; Herk, van A.M.

    2004-01-01

    Propagation rate coefficients, kp, for free-radical polymerization of butyl acrylate (BA) previously reported by several groups are critically evaluated. All data were determined by the combination of pulsed-laser polymerization (PLP) and subsequent polymer analysis by size exclusion (SEC)

  4. EPR detection of free radicals in UV-irradiated skin: mouse versus human

    International Nuclear Information System (INIS)

    Jurkiewicz, B.A.; Buettner, G.R.

    1996-01-01

    Ultraviolet radiation produces free radicals in Skh-1 mouse skin, contributing to photoaging and carcinogenesis. If a mouse model is a general indicator of free radical processes in human skin photobiology, then radical production observed in mouse and human skin should be directly comparative. In this work we show that UV radiation (λ > 300 nm, 14 μW/cm 2 UVB; 3.5 mW/cm 2 UVA) increases the ascorbate free radical (Asc) electron paramagnetic resonance (EPR) signal in both Skh-1 mouse skin (45%) and human facial skin biopsies (340%). Visible light (λ > 400 nm; 0.23 mW/cm 2 UVA) also increased the Ascsignal in human skin samples (45%) but did not increase baseline mouse Asc, indicating that human skin is more susceptible to free radical formation and that a chromophore for visible light may be present. Using EPR spin-trapping techniques, UV radiation produced spin adducts consistent with trapping lipid alkyl radicals in mouse skin (α-[4-pyridyl 1-oxide]-N-tert-butyl nitrone/alkyl radical adduct; a N = 15.56 G and a H 2.70 G) and lipid alkoxyl radicals in human skin (5,5-dimethylpyrroline -1-oxide/alkoxyl radical adduct; a N = 14.54 G and a H = 16.0 G). Topical application of the iron chelator Desferal to human skin significantly decreases these radicals (∼50%), indicating a role for iron in lipid peroxidation. (Author)

  5. Apoptotic and free radical scavenging properties of the methanolic extract of Gentianella alborosea.

    Science.gov (United States)

    Acero, Nuria; Llinares, Francisco; Galán de Mera, Antonio; Oltra, Beatriz; Muñoz-Mingarro, Dolores

    2006-09-01

    Gentianella alborosea ("Hercampure") is a Peruvian species used in folk medicine for the treatment of a variety of health disorders. We tested the free radical scavenging (DPPH) and induction of apoptosis on a human uterus tumor cell line (HeLa) by its methanolic extract. The results showed a noticeable radical scavenging activity and a dose-dependent apoptotic effect.

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

    Directory of Open Access Journals (Sweden)

    Yu Chen

    2010-08-01

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

  7. Postirradiation disturbances in peripheral nerve regeneration and role of free radical oxidation products in their occurrence

    International Nuclear Information System (INIS)

    Radlinskaya, V.N.; Zhutaev, I.A.; Bobyrev, V.N.; Voskresenskij, O.N.

    1985-01-01

    Long-term keeping of guinea pigs on antioxidant-free diet was shown to increase the rate of free-radical oxidation processes after local exposure to 20 Gy γ-radiation. Alimentary antioxidant deficiency enhanced new formation and growth of young axons, inhibited myelinization both in the exposed ad contralateral nonirradiated nerves being regenarated after ligating thereof

  8. In vitro anti-inflammatory and free radical scavenging activities of ...

    African Journals Online (AJOL)

    Methods: In vitro antioxidant activity was determined using free radical scavenging assays such as DPPH, ABTS and NO2. The antiinflammatory potential was carried out using inhibition of protein denaturation of egg albumin as a model of anti-inflammatory capacity. Results: Both the crude methanolic extract and saponins ...

  9. EPR of free radicals in solids I trends in methods and applications

    CERN Document Server

    Lund, Anders; Lund, Anders

    2012-01-01

    In its updated 2nd edition, this book surveys methods and applications of EPR in the study of free radical processes in solids. The focus is on trends in methods for extracting structural and dynamical properties of radicals and spin probes in solid matrices.

  10. Free radical production induced by methamphetamine in rat striatal synaptosomes

    International Nuclear Information System (INIS)

    Pubill, David; Chipana, Carlos; Camins, Antonio; Pallas, Merce; Camarasa, Jordi; Escubedo, Elena

    2005-01-01

    The pro-oxidative effect of methamphetamine (METH) in dopamine terminals was studied in rat striatal synaptosomes. Flow cytometry analysis showed increased production of reactive oxygen species (ROS) in METH-treated synaptosomes, without reduction in the density of dopamine transporters. In synaptosomes from dopamine (DA)-depleted animals, METH did not induce ROS production. Reserpine, in vitro, completely inhibited METH-induced ROS production. These results point to endogenous DA as the main source of ROS induced by METH. Antioxidants and inhibitors of neuronal nitric oxide synthase and protein kinase C (PKC) prevented the METH-induced oxidative effect. EGTA and the specific antagonist methyllycaconitine (MLA, 50 μM) prevented METH-induced ROS production, thus implicating calcium and α7 nicotinic receptors in such effect. Higher concentrations of MLA (>100 μM) showed nonspecific antioxidant effect. Preincubation of synaptosomes with METH (1 μM) for 30 min reduced [ 3 H]DA uptake by 60%. The METH effect was attenuated by MLA and EGTA and potentiated by nicotine, indicating that activation of α 7 nicotinic receptors and Ca 2+ entry are necessary and take place before DAT inhibition. From these findings, it can be postulated that, in our model, METH induces DA release from synaptic vesicles to the cytosol. Simultaneously, METH activates α 7 nicotinic receptors, probably inducing depolarization and an increase in intrasynaptosomal Ca 2+ . This would lead to DAT inhibition and NOS and PKC activation, initiating oxidation of cytosolic DA

  11. TRAPPING HO2 FREE RADICAL IN SONICATED WATER%空化水中HO2自由基的捕获

    Institute of Scientific and Technical Information of China (English)

    刘岩; 王军

    2003-01-01

    @@ 1 INTRODUCTION As a new advanced oxidation process (AOP) in water treatment, sonochemistry in water treatment has been paid more attention for one decade[1-7]. The collapsed cavitation bubbles give rise to high temperature and high pressure[8] to generate free radical, e.g. OH, O, HO2 in sonicated water. These kinds of radicals can oxidize the organic substances dissolved in water.

  12. Controlled free radical polymerization of vinyl acetate with cobalt ...

    Indian Academy of Sciences (India)

    The high molecular weight of polyvinyl acetate (PVAc) with its relatively low molecular distribution without unreacted monomer ... properties of the polymer indicated a lower glass transition state. The easily ..... vision software). The ease of ...

  13. Photoionization and High Density Gas

    Science.gov (United States)

    Kallman, T.; Bautista, M.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We present results of calculations using the XSTAR version 2 computer code. This code is loosely based on the XSTAR v.1 code which has been available for public use for some time. However it represents an improvement and update in several major respects, including atomic data, code structure, user interface, and improved physical description of ionization/excitation. In particular, it now is applicable to high density situations in which significant excited atomic level populations are likely to occur. We describe the computational techniques and assumptions, and present sample runs with particular emphasis on high density situations.

  14. High-density multicore fibers

    DEFF Research Database (Denmark)

    Takenaga, K.; Matsuo, S.; Saitoh, K.

    2016-01-01

    High-density single-mode multicore fibers were designed and fabricated. A heterogeneous 30-core fiber realized a low crosstalk of −55 dB. A quasi-single-mode homogeneous 31-core fiber attained the highest core count as a single-mode multicore fiber.......High-density single-mode multicore fibers were designed and fabricated. A heterogeneous 30-core fiber realized a low crosstalk of −55 dB. A quasi-single-mode homogeneous 31-core fiber attained the highest core count as a single-mode multicore fiber....

  15. The applications of VIP 397/418 bulbs in free radical white pigmented coatings: UV curing evaluation for different free radical white pigmented formulations (I)

    International Nuclear Information System (INIS)

    Rong Bao; McCartney, R.

    1999-01-01

    White pigmented coatings have gained commercial success using a Gallium doped microwave F600-V bulb. A novel VIP 397/418 bulb has been made recently, by Fusion UV Systems, to increase UV curing efficiency of white pigmented coatings. Previous research work has shown that the VIP 397/418 bulb can cure cationic white pigmented coatings 40-60% faster than a F600-V bulb. Further evaluations of free radical white pigmented coatings have produced significant data indicating that better physical properties (40-50%) or higher cure speeds (50%) can be obtained by using the VIP 397/418 bulb than a F600-V bulb

  16. High density matter at RHIC

    Indian Academy of Sciences (India)

    QCD predicts a phase transition between hadronic matter and a quark-gluon plasma at high energy density. The relativistic heavy ion collider (RHIC) at Brookhaven National Laboratory is a new facility dedicated to the experimental study of matter under extreme conditions. Already the first round of experimental results at ...

  17. Application of EPR spectroscopy to examine free radicals evolution during storage of the thermally sterilized Ungentum ophthalmicum.

    Science.gov (United States)

    Ramos, Paweł; Pilawa, Barbara

    2016-06-24

    Free radicals formed during thermal sterilization of the Ungentum ophthalmicum were examined by an X-band EPR spectroscopy. The influence of storage time (15 min; 1, 2 and 3 days after heating) on free radical properties and concentrations in this sample was determined. Thermal sterilization was done according to the pharmaceutical norms. The first-derivative EPR spectra with g-values about 2 were measured with magnetic modulation of 100 kHz in the range of microwave power 2.2-70 mW. The changes of amplitudes (A) and linewidths (ΔB pp ) with microwave powers were evaluated. Free radicals in concentration ∼10 17 spin/g were formed during heating of the tested Ungentum. Free radical concentration decreased with increase in storage time, and reached values ∼10 17 spin/g after 3 days from sterilization. The tested U. ophthalmicum should not be sterilized at a temperature of 160 °C because of the free radicals formation, or it should be used 3 days after heating, when free radicals were considerably quenched. Free radical properties remain unchanged during storage of the Ungentum. The EPR lines of the U. ophthalmicum were homogeneously broadened and their linewidths (ΔB pp ) increased with increase in microwave power. EPR spectroscopy is useful to examine free radicals to optimize sterilization process and storage conditions of ophthalmologic samples.

  18. High density operation in pulsator

    International Nuclear Information System (INIS)

    Klueber, O.; Cannici, B.; Engelhardt, W.; Gernhardt, J.; Glock, E.; Karger, F.; Lisitano, G.; Mayer, H.M.; Meisel, D.; Morandi, P.

    1976-03-01

    This report summarizes the results of experiments at high electron densities (>10 14 cm -3 ) which have been achieved by pulsed gas inflow during the discharge. At these densities a regime is established which is characterized by βsub(p) > 1, nsub(i) approximately nsub(e), Tsub(i) approximately Tsub(e) and tausub(E) proportional to nsub(e). Thus the toroidal magnetic field contributes considerably to the plasma confinement and the ions constitute almost half of the plasma pressure. Furthermore, the confinement is appreciably improved and the plasma becomes impermeable to hot neutrals. (orig.) [de

  19. Free Br atom and free radical reactions in the radiolysis of 1,2 dibromoethane (DBE) in air free aqueous solutions

    International Nuclear Information System (INIS)

    Lal, Manohar

    1986-01-01

    G(Br - ) have been reported in the free radical degradation of 1,2 DBE in Ar - and N 2 O-saturated solutions. It is clear from the results that a small chain reaction occurs, t-butanol radical reacts with 1,2 DBE to give Br - . At pH 12.3, high (Br - ) are attributed to another chain reaction involving O - radical anion. Dose rate studies confirm the occurrence of chain reaction. (author). 5 refs

  20. Outrunning free radicals in room-temperature macromolecular crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Owen, Robin L., E-mail: robin.owen@diamond.ac.uk; Axford, Danny [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); Nettleship, Joanne E.; Owens, Raymond J. [Rutherford Appleton Laboratory, Didcot OX11 0FA (United Kingdom); The Henry Wellcome Building for Genomic Medicine, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Robinson, James I.; Morgan, Ann W. [University of Leeds, Leeds LS9 7FT (United Kingdom); Doré, Andrew S. [Heptares Therapeutics Ltd, BioPark, Welwyn Garden City AL7 3AX (United Kingdom); Lebon, Guillaume; Tate, Christopher G. [MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH (United Kingdom); Fry, Elizabeth E.; Ren, Jingshan [The Henry Wellcome Building for Genomic Medicine, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Stuart, David I. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); The Henry Wellcome Building for Genomic Medicine, Roosevelt Drive, Oxford OX3 7BN (United Kingdom); Evans, Gwyndaf [Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom)

    2012-06-15

    A systematic increase in lifetime is observed in room-temperature protein and virus crystals through the use of reduced exposure times and a fast detector. A significant increase in the lifetime of room-temperature macromolecular crystals is reported through the use of a high-brilliance X-ray beam, reduced exposure times and a fast-readout detector. This is attributed to the ability to collect diffraction data before hydroxyl radicals can propagate through the crystal, fatally disrupting the lattice. Hydroxyl radicals are shown to be trapped in amorphous solutions at 100 K. The trend in crystal lifetime was observed in crystals of a soluble protein (immunoglobulin γ Fc receptor IIIa), a virus (bovine enterovirus serotype 2) and a membrane protein (human A{sub 2A} adenosine G-protein coupled receptor). The observation of a similar effect in all three systems provides clear evidence for a common optimal strategy for room-temperature data collection and will inform the design of future synchrotron beamlines and detectors for macromolecular crystallography.

  1. Outrunning free radicals in room-temperature macromolecular crystallography

    International Nuclear Information System (INIS)

    Owen, Robin L.; Axford, Danny; Nettleship, Joanne E.; Owens, Raymond J.; Robinson, James I.; Morgan, Ann W.; Doré, Andrew S.; Lebon, Guillaume; Tate, Christopher G.; Fry, Elizabeth E.; Ren, Jingshan; Stuart, David I.; Evans, Gwyndaf

    2012-01-01

    A systematic increase in lifetime is observed in room-temperature protein and virus crystals through the use of reduced exposure times and a fast detector. A significant increase in the lifetime of room-temperature macromolecular crystals is reported through the use of a high-brilliance X-ray beam, reduced exposure times and a fast-readout detector. This is attributed to the ability to collect diffraction data before hydroxyl radicals can propagate through the crystal, fatally disrupting the lattice. Hydroxyl radicals are shown to be trapped in amorphous solutions at 100 K. The trend in crystal lifetime was observed in crystals of a soluble protein (immunoglobulin γ Fc receptor IIIa), a virus (bovine enterovirus serotype 2) and a membrane protein (human A 2A adenosine G-protein coupled receptor). The observation of a similar effect in all three systems provides clear evidence for a common optimal strategy for room-temperature data collection and will inform the design of future synchrotron beamlines and detectors for macromolecular crystallography

  2. Free radicals, reactive oxygen species, oxidative stress and its classification.

    Science.gov (United States)

    Lushchak, Volodymyr I

    2014-12-05

    Reactive oxygen species (ROS) initially considered as only damaging agents in living organisms further were found to play positive roles also. This paper describes ROS homeostasis, principles of their investigation and technical approaches to investigate ROS-related processes. Especial attention is paid to complications related to experimental documentation of these processes, their diversity, spatiotemporal distribution, relationships with physiological state of the organisms. Imbalance between ROS generation and elimination in favor of the first with certain consequences for cell physiology has been called "oxidative stress". Although almost 30years passed since the first definition of oxidative stress was introduced by Helmut Sies, to date we have no accepted classification of oxidative stress. In order to fill up this gape here classification of oxidative stress based on its intensity is proposed. Due to that oxidative stress may be classified as basal oxidative stress (BOS), low intensity oxidative stress (LOS), intermediate intensity oxidative stress (IOS), and high intensity oxidative stress (HOS). Another classification of potential interest may differentiate three categories such as mild oxidative stress (MOS), temperate oxidative stress (TOS), and finally severe (strong) oxidative stress (SOS). Perspective directions of investigations in the field include development of sophisticated classification of oxidative stresses, accurate identification of cellular ROS targets and their arranged responses to ROS influence, real in situ functions and operation of so-called "antioxidants", intracellular spatiotemporal distribution and effects of ROS, deciphering of molecular mechanisms responsible for cellular response to ROS attacks, and ROS involvement in realization of normal cellular functions in cellular homeostasis. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  3. Cultured rat and purified human Pneumocystis carinii stimulate intra- but not extracellular free radical production in human neutrophils

    DEFF Research Database (Denmark)

    Jensen, T; Aliouat, E M; Lundgren, B

    1998-01-01

    The production of free radicals in human neutrophils was studied in both Pneumocystis carinii derived from cultures of L2 rat lung epithelial-like cells and Pneumocystis carinii purified from human lung. Using the cytochrome C technique, which selectively measured extracellular superoxide...... generation, hardly any free radical production was observed after stimulation with cultured rat-derived P. carinii. A chemiluminescence technique, which separately measured intra- and extracellular free radical production, was subsequently employed to differentiate the free radical generation....... It was established that 1) P. carinii stimulated intra- but not extracellular free radical production in human neutrophils, 2) opsonized cultured rat-derived P. carinii stimulated human neutrophils to a strong intracellular response of superoxide production, and 3) opsonized P. carinii, purified from human lung also...

  4. Infrared absorption spectroscopy and chemical kinetics of free radicals

    International Nuclear Information System (INIS)

    Curl, R.F.; Glass, G.P.

    1991-01-01

    A new channel producing ketenyl radical (HCCO) was discovered in the flash photolysis of ketene at 193 nm. H 2 CCO + hν(193 nm) → H + HCCO by observation near 2020 cm -1 of the infrared fundamental of ketenyl corresponding to the antisymmetric motion of the heavy atoms. This band has been partially rotationally analyzed and the rate constant for the reaction of ketenyl with NO has been determined. The OH stretching fundamental of hydroxymethyl radical (CH 2 OH) has been observed near 3600 cm -1 producing the radical either by the excimer flash photolysis of acetol (CH 3 COCH 2 OH) or by Cl atom abstraction of a methyl hydrogen from methanol. The assignment of the spectrum to CH 2 OH was confirmed by the agreement of the rate constant for the reaction of the species with O 2 with the literature value. The mechanism of the reaction of C 2 H with O 2 has been explored. There appear to be two channels producing CO product: a fast, direct one producing highly vibrationally excited CO up to v = 6 at the same rate C 2 H disappears and a slow, indirect one producing primarily ground state CO on a much longer timescale than the disappearance of C 2 H. The rate constants for the reactions of C 2 H with CH 4 , C 2 H 6 , C 2 H 4 , D 2 , and CO were determined by following the time decay of a C 2 H infrared transient absorption line originating from the ground vibronic state using diode laser spectroscopy creating the C 2 H by excimer laser flash photolysis (ArF, 193 nm) of CF 3 CCH. The branching ratio into OH of the reaction between NH 2 , and NO, which is the channel thought to propagate the radical chain of the Thermal deNOx process, has been measured up to 925 degree C. The OH yield thus obtained appears to be too small to maintain the process. 5 refs., 3 figs

  5. Oxidation of free, peptide and protein tryptophan residues mediated by AAPH-derived free radicals: role of alkoxyl and peroxyl radicals

    DEFF Research Database (Denmark)

    Fuentes-Lemus, E.; Dorta, E.; Escobar, E.

    2016-01-01

    The oxidation of tryptophan (Trp) residues, mediated by peroxyl radicals (ROOc), follows a complex mechanism involving free radical intermediates, and short chain reactions. The reactivity of Trp towards ROOc should be strongly affected by its inclusion in peptides and proteins. To examine...... the latter, we investigated (by fluorescence) the kinetic of the consumption of free, peptide- and protein-Trp residues towards AAPH (2,20 -azobis(2-amidinopropane)dihydrochloride)-derived free radicals. Interestingly, the initial consumption rates (Ri ) were only slightly influenced by the inclusion of Trp...... concentrations (10–50 mM), the values of Ri were nearly constant; and at high Trp concentrations (50 mM to 1 mM), a slower increase of Ri than expected for chain reactions. Similar behavior was detected for all three systems (free Trp, and Trp in peptides and proteins). For the first time we are showing...

  6. The Intensity of Free Radical Processes and the Testosterone and Estradiol Levels in Seminal Fluid of Men with Different Types of Pathospermia - Personalized Approach

    Directory of Open Access Journals (Sweden)

    Shkurat T

    2016-05-01

    Full Text Available Background: We studied the intensity of free-radical processes and the testosterone and estradiol levels in seminal fluid of men with normospermia, asthenozoospermia, oligozoospermia, oligoasthenozoospermia, teratozoospermia. Results: An increased ability to generate reactive oxygen species in seminal fluid in patients with oligozoospermia was determined. Increased levels of testosterone and estradiol in semen were noted in pathospermia associated with reduced sperm motility. A positive correlation was found between the free-radical processes intensity and testosterone levels increase, and high correlation (r = 0.8 between the testosterone and estradiol levels in seminal fluid in patients with oligozoospermia was marked. Conclusion: The prooxidant and antioxidant processes conjugacy violation occurs in one of the pathospermia types - asthenozoospermia, which is reflected in the absence of all studied parameters correlation in the seminal fluid.

  7. Free radical behaviours during methylene blue degradation in the Fe2+/H2O2 system.

    Science.gov (United States)

    Wang, Zhonghua; Zhao, Haiqian; Qi, Hanbing; Liu, Xiaoyan; Liu, Yang

    2017-12-22

    Behaviours of the free radicals during the methylene blue (MB) oxidation process in the Fe 2+ /H 2 O 2 system were studied to reveal the reason for the low utilization efficiency of H 2 O 2 . The roles of [Formula: see text], [Formula: see text] and [Formula: see text] radicals were proven to be different in the MB oxidation process. The results showed that [Formula: see text] radicals had a strong ability to oxidize MB; however, they were not the main active substances for MB degradation due to the low concentration in the traditional Fe 2+ /H 2 O 2 system. [Formula: see text] radicals could not oxidize MB. [Formula: see text] radicals were the main active substances for MB oxidation. In the short initial stage, the utilization efficiency of H 2 O 2 was high, because the generation rate of [Formula: see text] was much higher than that of [Formula: see text]. More [Formula: see text] radicals were involved in the MB oxidation reaction. In the long deceleration stage (after the short initial stage), a large amount of H 2 O 2 was consumed, but the amount of oxidized MB was very small. Most of the [Formula: see text] radicals were consumed via the rapid useless reaction between [Formula: see text] and [Formula: see text] in this stage, resulting in the serious useless consumption of H 2 O 2 . It is a feasible method to improve the utilization efficiency of H 2 O 2 by adding suitable additives into the Fe 2+ /H 2 O 2 system to weaken the useless reaction between [Formula: see text] and [Formula: see text].

  8. Edaravone, a free radical scavenger, attenuates cerebral infarction and hemorrhagic infarction in rats with hyperglycemia.

    Science.gov (United States)

    Okamura, Koichi; Tsubokawa, Tamiji; Johshita, Hiroo; Miyazaki, Hiroshi; Shiokawa, Yoshiaki

    2014-01-01

    Thrombolysis due to acute ischemic stroke is associated with the risk of hemorrhagic infarction, especially after reperfusion. Recent experimental studies suggest that the main mechanism contributing to hemorrhagic infarction is oxidative stress caused by disruption of the blood-brain barrier. Edaravone, a free radical scavenger, decreases oxidative stress, thereby preventing hemorrhagic infarction during ischemia and reperfusion. In this study, we investigated the effects of edaravone on hemorrhagic infarction in a rat model of hemorrhagic transformation. We used a previously established hemorrhagic transformation model of rats with hyperglycemia. Hyperglycemia was induced by intraperitoneal injection of glucose to all rats (n  =  20). The rats with hyperglycemia showed a high incidence of hemorrhagic infarction. Middle cerebral artery occlusion (MCAO) for 1.5 hours followed by reperfusion for 24 hours was performed in edaravone-treated rats (n  =  10) and control rats (n  =  10). Upon completion of reperfusion, both groups were evaluated for infarct size and hemorrhage volume and the results obtained were compared. Edaravone significantly decreased infarct volume, with the average infarct volume in the edaravone-treated rats (227.6 mm(3)) being significantly lower than that in the control rats (264.0 mm(3)). Edaravone treatment also decreased the postischemic hemorrhage volumes (53.4 mm(3) in edaravone-treated rats vs 176.4 mm(3) in controls). In addition, the ratio of hemorrhage volume to infarct volume was lower in the edaravone-treated rats (23.5%) than in the untreated rats (63.2%). Edaravone attenuates cerebral infarction and hemorrhagic infarction in rats with hyperglycemia.

  9. [Correlation of Persistent Free Radicals, PCDD/Fs and Metals in Waste Incineration Fly Ash].

    Science.gov (United States)

    Wang, Tian-jiao; Chen, Tong; Zhan, Ming-xiu; Guo, Ying; Li, Xiao-dong

    2016-03-15

    Environmentally persistent free radicals (EPFRs) are relatively highly stable and found in the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Recent studies have concentrated on model dioxin formation reactions and there are few studies on actual waste incineration fly ash. In order to study EPFRs and the correlation with dioxins and heavy metals in waste incineration fly ash, the spins of EPFRs, concentration of PCDD/Fs and metals in samples from 6 different waste incinerators were detected. The medical waste incineration fly ash from Tianjin, municipal solid waste incineration fly ash from Jiangxi Province, black carbon and slag from municipal solid waste incinerator in Lanxi, Zhejiang Province, all contained EPFRs. Above all the signal in Tianjin sample was the strongest. Hydroxyl radicals, carbon-center radicals and semiquinone radicals were detected. Compared with other samples, Jiangxi fly ash had the highest toxic equivalent quantity (TEQ) of dioxins, up to 7.229 4 ng · g⁻¹. However, the dioxin concentration in the Tianjin sample containing the strongest EPFR signals was only 0.092 8 ng · g⁻¹. There was perhaps little direct numeric link between EPFRs and PCDD/Fs. But the spins of EPFRs in samples presented an increasing trend as the metal contents increased, especially with Al, Fe, Zn. The signal strength of radicals was purposed to be related to the metal contents. The concentration of Zn (0.813 7% ) in the Tianjin sample was the highest and this sample contained much more spins of oxygen-center radicals. We could presume the metal Zn had a greater effect on the formation of EPFRs, and was easier to induce the formation of radicals with a longer half-life period.

  10. Radiation-electrochemistry of the colloidal gold micro-electrode: Hydrogen formation by organic free radicals

    International Nuclear Information System (INIS)

    Westerhausen, J.; Henglein, A.; Lilie, J.

    1981-01-01

    Various organic free radicals as well as Ni + ions produce hydrogen in the presence of some 10 -4 M of colloidal gold. The gold catalyst was prepared via the reduction of HAuCl 4 either thermally by citrate or by γ-irradiation. The organic radicals were radiolytically produced. The mechanism of H 2 formation includes electron transfer from the organic radicals to the gold particles, storage of a large number of electrons per gold particle, conversion of the electrons into adsorbed H-atoms and desorption of the latter to form H 2 . - The rates of some of these steps were measured using the method of pulse radiolysis. 1-Hydroxy-1-methyl ethyl radicals, (CH 3 ) 2 COH, react with colloidal gold particles almost diffusion controlled provided that the gold particles are not charged with excess electrons. Charged gold particles react at a substantially lower rate. The stored electrons live seconds or even minutes depending on their number per gold particle. In the stationary state, up to 0.38 Coulomb of electrons could be stored per liter of a 2.9x10 -4 molar gold solution, each gold particle carrying about 39 electrons. A comparison is also made between the catalytic activities of colloidal gold and silver. Due to the relative fast conversion of electrons into adsorbed H-atoms, colloidal gold has less capacity for the storage of electrons than colloidal silver. - The dependence of the hydrogen yield on the pH of the solution, the concentration of gold, the size of the gold particles, the concentration of the polyvinyl alcohol stabilizer, and the intensity of radiation was also investigated. At high intensities, some of the radicals are destroyed in a gold catalysed disproportionation. (orig.)

  11. Aerosol Fragmentation Driven by Coupling of Acid-Base and Free-Radical Chemistry in the Heterogeneous Oxidation of Aqueous Citric Acid by OH Radicals.

    Science.gov (United States)

    Liu, Matthew J; Wiegel, Aaron A; Wilson, Kevin R; Houle, Frances A

    2017-08-10

    A key uncertainty in the heterogeneous oxidation of carboxylic acids by hydroxyl radicals (OH) in aqueous-phase aerosol is how the free-radical reaction pathways might be altered by acid-base chemistry. In particular, if acid-base reactions occur concurrently with acyloxy radical formation and unimolecular decomposition of alkoxy radicals, there is a possibility that differences in reaction pathways impact the partitioning of organic carbon between the gas and aqueous phases. To examine these questions, a kinetic model is developed for the OH-initiated oxidation of citric acid aerosol at high relative humidity. The reaction scheme, containing both free-radical and acid-base elementary reaction steps with physically validated rate coefficients, accurately predicts the experimentally observed molecular composition, particle size, and average elemental composition of the aerosol upon oxidation. The difference between the two reaction channels centers on the reactivity of carboxylic acid groups. Free-radical reactions mainly add functional groups to the carbon skeleton of neutral citric acid, because carboxylic acid moieties deactivate the unimolecular fragmentation of alkoxy radicals. In contrast, the conjugate carboxylate groups originating from acid-base equilibria activate both acyloxy radical formation and carbon-carbon bond scission of alkoxy radicals, leading to the formation of low molecular weight, highly oxidized products such as oxalic and mesoxalic acid. Subsequent hydration of carbonyl groups in the oxidized products increases the aerosol hygroscopicity and accelerates the substantial water uptake and volume growth that accompany oxidation. These results frame the oxidative lifecycle of atmospheric aerosol: it is governed by feedbacks between reactions that first increase the particle oxidation state, then eventually promote water uptake and acid-base chemistry. When coupled to free-radical reactions, acid-base channels lead to formation of low molecular

  12. The Cytotoxic, Antibacterial and Free Radical Scavenging Activities of Crude Extracts of Matricaria chamomilla, Salvadora persica and Artemisia annua

    KAUST Repository

    Seddek, Ahmed

    2011-12-01

    The discovery of drugs from natural sources has been a rapidly growing science in this era. Plants used for medicinal purposes have been usually studied as rich sources of bioactive chemical compounds that can be used as medications. Several plant-derived drugs have been approved so far. Cancer and infectious diseases have been common targets for the science of drug discovery, due to the high mortality rates caused by these diseases all over the world. Several plant-derived compounds are being marketed now as anti-cancer agents. However, finding novel antimicrobial and anti-cancer compounds has become an important goal to overcome the problems of existing anti-cancer and antimicrobial agents, such as resistance and non-selectivity. In this thesis project, an attempt to find out useful biological activities of the crude extracts of some plants used traditionally for medicinal purposes in Saudi Arabia has been made. Matricaria chamomilla, Salvadora persica and Artemisia annua have been selected for study, based on the literature review performed. These plants were screened for three biological activities; anti-cancer, anti-bacterial and free radical scavenging activities. The experimental part of the study consisted of some common in-vitro techniques, such as cytotoxicity and cell viability assays, disk diffusion assay and 1,1-diphenyl-2-picryl-hydrazyl assay. In addition, the crude extract of Matricaria chamomilla has undergone chemical fractionation and four solvent fractions were obtained using column chromatography. The crude extract of Matricaria chamomilla showed a promising anti-bacterial activity against Escherichia coli and a very promising free radical scavenging activity that was comparable to ascorbic acid, an important anti-oxidant. The four solvent fractions obtained from that extract showed that these activities were produced by more than one compound belonging to different solvent fractions. In addition, the crude extract of Artemisia annua showed

  13. The effect of the diazepam to the free radical under the brain radiation injury

    International Nuclear Information System (INIS)

    Huo Hongmei; Wang Chen; Zhang Zhilin

    2007-01-01

    Objective: To study the effect of the diazepam on free radical under in the brain radiation injury in the early stage. Methods: A model of whole brain radiation injury in wakefulness was established in the Sprague-Dawley rat. Diazepam was given intraperitoneally 30 minutes before radiation. The brain tissue homogenate was prepared respectively while the rats were executed 6 hours, 1 day, 1 week, 1 month after irradiation. The contents of the superoxide dismutase (SOD) and the malondialdehyde (MDA) in the tissue homogenate were measured by chemical colorimetry. Results: Diazepam could increase the vigor of SOD and reduce the MDA contents after irradiated. Conclusions: Diazepam has certain neuroprotection effect on radiation injury and decreasing the level of the free radicals. (authors)

  14. Antinociceptive and free radical scavenging activities of Cocos nucifera L. (Palmae) husk fiber aqueous extract.

    Science.gov (United States)

    Alviano, Daniela S; Rodrigues, Karen F; Leitão, Suzana G; Rodrigues, Marcio L; Matheus, Maria Eline; Fernandes, Patrícia D; Antoniolli, Angelo R; Alviano, Celuta S

    2004-06-01

    In the current study, the analgesic and free radical scavenging properties of an aqueous extract from the husk fiber of Cocos nucifera L. (Palmae) were demonstrated by the use of in vivo and in vitro models. The orally administered Cocos nucifera aqueous extract (200 or 400 mg/kg) inhibited the acetic acid-induced writhing response in mice. Tail flick and hot plate assays demonstrated that treatment of animals with this plant extract at 200 mg/kg induced attenuation in the response to a heat stimulus. A LD(50) of 2.30 g/kg was obtained in acute toxicity tests. Topic treatment of rabbits with the Cocos nucifera extract indicated that it does not induce any significant dermic or ocular irritation. In vitro experiments using the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) photometric assay demonstrated that this plant extract also possesses free radical scavenging properties.

  15. Detection of organic free radicals in irradiated pepper by electron spin resonance

    International Nuclear Information System (INIS)

    Ukai, Mitsuko; Shimoyama, Yuhei

    2002-01-01

    Using electron spin resonance (ESR) spectroscopy, we revealed various free radicals in a Japanese commercially available black pepper before and after γ-irradiation. The representative ESR spectrum of the pepper is composed of a sextet centered at g=2.0, a singlet at the same g-value and a singlet at g=4.0. The first one is attributable to a signal with hyperfine interactions of Mn 2+ ion (7.4 mT). The second one is due to an organic free radical. The third one may be originated from Fe 3+ ion of the non-hem Fe in proteins. A pair of signals appeared in the black pepper after γ-irradiation. The progressive saturation behavior reconfirmed the signal identification for the radicals in the black pepper. (author)

  16. The application of radiation-induced free radicals signals in retrospective dosimetry

    International Nuclear Information System (INIS)

    Liu Zhongchao; Zhang Wenyi; Jiao Ling

    2013-01-01

    For some materials and biological samples, free radicals can be induced after ionizing radiation. Electron spin resonance (ESR) spectroscopy can detect free radical signal and its intensity can reflect the dose of the ionizing radiation. It is a typical way to estimate the radiation dosimetry by using the ESR spectroscopy of teeth. In recent years, many researchers studied on ESR of easy-getting materials such as finger (toe) nail, hair, cell phone screen, in order to investigate the relationship between signal intensity and radiation dose. The aim of this paper is to survey the current literature about methodologies and the materials on background signal, linearity of dose-response relationship, minimum detection limit and post-irradiation signal stability, so that more data will be provided for nuclear accident dose estimation. (authors)

  17. Free radical scavenging activities of yellow gentian (Gentiana lutea L.) measured by electron spin resonance.

    Science.gov (United States)

    Kusar, A; Zupancic, A; Sentjurc, M; Baricevic, D

    2006-10-01

    Yellow gentian (Gentiana lutea L.) is a herbal species with a long-term use in traditional medicine due to its digestive and stomachic properties. This paper presents an investigation of the free radical scavenging activity of methanolic extracts of yellow gentian leaves and roots in two different systems using electron spin resonance (ESR) spectrometry. Assays were based on the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) and the superoxide radicals (O2*-) generated by the xanthine/xanthine oxidase (X/XO) system. The results of gentian methanolic extracts were compared with the antioxidant capacity of synthetic antioxidant butylated hydroxyanisole (BHA). This study proves that yellow gentian leaves and roots exhibit considerable antioxidant properties, expressed either by their capability to scavenge DPPH or superoxide radicals.

  18. Antitumor potential induction and free radicals production in melanoma cells by Boron Neutron Capture Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Faiao-Flores, F. [Biochemical and Biophysical Laboratory, Butantan Institute, 1500 Vital Brasil Avenue, Sao Paulo (Brazil)] [Faculty of Medicine, University of Sao Paulo, 455 Doutor Arnaldo Avenue, Sao Paulo (Brazil); Coelho, P.R.P.; Muniz, R.O.R.; Souza, G.S. [Institute for Nuclear and Energy Research, 2242 Lineu Prestes Avenue, Sao Paulo (Brazil); Arruda-Neto, J. [Physics Institute, University of Sao Paulo, 187 Matao Street, Sao Paulo (Brazil)] [FESP, Sao Paulo Engineering School, 5520 Nove de Julho Avenue, Sao Paulo (Brazil); Maria, Durvanei A., E-mail: durvaneiaugusto@yahoo.com.br [Biochemical and Biophysical Laboratory, Butantan Institute, 1500 Vital Brasil Avenue, Sao Paulo (Brazil)

    2011-12-15

    Antiproliferative and oxidative damage effects occurring in Boron Neutron Capture Therapy (BNCT) in normal fibroblasts and melanoma cell lines were analyzed. Melanoma cells and normal fibroblasts were treated with different concentrations of Boronophenylalanine and irradiated with thermal neutron flux. The cellular viability and the oxidative stress were determined. BNCT induced free radicals production and proliferative potential inhibition in melanoma cells. Therefore, this therapeutic technique could be considered efficient to inhibit growth of melanoma with minimal effects on normal tissues. - Highlights: Black-Right-Pointing-Pointer Boron Neutron Capture Therapy (BNCT) induces melanoma cell death. Black-Right-Pointing-Pointer BNCT stimulates free radicals production and proliferative inhibition in melanoma cells. Black-Right-Pointing-Pointer It produces tumor membrane degeneration and destruction with apoptotic bodies formation. Black-Right-Pointing-Pointer This therapy damages tumor cells selectively, with minimum effects on normal adjacent tissue.

  19. Free radicals, oxidative stress and importance of antioxidants in human health

    Directory of Open Access Journals (Sweden)

    K.I. Priyadarsini

    2011-07-01

    Full Text Available Reactive oxygen species (ROS is a collective term used for oxygen containing free radicals, depending on their reactivity and oxidizing ability. ROS participate in a variety of chemical reactions with biomolecules leading to a pathological condition known as oxidative stress. Antioxidants are employed to protect biomolecules from the damaging effects of such ROS. In the beginning, antioxidant research was mainly aimed at understanding free radical reactions of ROS with antioxidants employing biochemical assays and kinetic methods. Later on, studies began to be directed to monitor the ability of anti-oxidants to modulate cellular signaling proteins like receptors, secondary messengers, transcription factors, etc. Of late several studies have indicated that antioxidants can also have deleterious effects on human health depending on dosage and bio-availability. It is therefore, necessary to validate the utility of antioxidants in improvement of human health in order to take full advantage of their therapeutic potential.

  20. Antioxidant and free radical scavenging activities of Gastrodia elata Bl. and Uncaria rhynchophylla (Miq.) Jacks.

    Science.gov (United States)

    Liu, J; Mori, A

    1992-12-01

    Gastrodia elata Bl. (GE) and Uncaria rhynchophylla (Miq.) Jacks (UR) are two traditional Chinese medicinal herbal drugs, used for the treatment of convulsions and epilepsy. Their antioxidant effects in vivo and their free radical scavenging effects in vitro were investigated. Epileptogenic foci in the lateral brain of the rat were induced by the injection of ferric chloride into the lateral cortex. Both extracts significantly inhibited the increase in levels of lipid peroxide in the ipsilateral cortex, at all times observed. In addition, the two extracts also induced an early increase of activity of superoxide dismutase in the mitochondrial fraction of the ipsilateral cortex. In in vitro experiments, the two extracts exhibited significant dose-dependent scavenging effects on free radicals, using electron spin resonance spectroscopy. These results suggest that the proposed antiepileptic effects of GE and UR may be attributable to the antioxidant activity of the active components in these two medicinal herbs.

  1. EPR persistence measurements of UV-induced melanin free radicals in whole skin

    International Nuclear Information System (INIS)

    Collins, B.; Poehler, T.O.; Bryden, W.A.

    1995-01-01

    Electron paramagnetic resonance is used to detect the formation of free radicals caused by exposure to ultraviolet radiation in chemically untreated rabbit skin. A fast jump in EPR signal level, occurring over a few seconds, is observed immediately after a skin sample is exposed to UV. This is followed by a slower increase toward an elevated steady-state signal over a period of hours as the skin is continuously exposed to a UV light source. Upon cessation of UV light exposure, EPR signal levels undergo an abrupt drop followed by a slower decay toward natural levels. Elevated free radical concentrations following UV exposure are found to persist for several hours in whole skin. These results are consistent with time resolved EPR measurements of photoinduced radicals in various natural melanins. (Author)

  2. High density fuel storage rack

    International Nuclear Information System (INIS)

    Zezza, L.J.

    1980-01-01

    High storage density for spent nuclear fuel assemblies in a pool achieved by positioning fuel storage cells of high thermal neutron absorption materials in an upright configuration in a rack. The rack holds the cells at required pitch. Each cell carries an internal fuel assembly support, and most cells are vertically movable in the rack so that they rest on the pool bottom. Pool water circulation through the cells and around the fuel assemblies is permitted by circulation openings at the top and bottom of the cells above and below the fuel assemblies

  3. Fermentation of Smilax china root by Aspergillus usami and Saccharomyces cerevisiae promoted concentration of resveratrol and oxyresveratrol and the free-radical scavenging activity.

    Science.gov (United States)

    Yoon, So-Ra; Yang, Seung-Hwan; Suh, Joo-Won; Shim, Soon-Mi

    2014-07-01

    Smilax china root, which is rich in resveratrol and oxyresveratrol, has been used as emergency foods as well as folk medicine. This study investigated changes in concentration of bioactive components and the free-radical scavenging capacity of Smilax china root during fermentation by Aspergillus usami and Saccharomyces cerevisiae. Resveratrol, oxyresveratrol and piceid were quantified as major constituents in Smilax china root by using UPLC-ESI-MS. The concentration of oxyresveratrol and resveratrol remarkably increased through fermentation and the transformation of piceid to resveratrol. Its concentration in 4% Smilax china root was 1.16-2.95 times higher than that of a 2% preparation throughout fermentation. The vitamin C equivalent antioxidant capacity of 2% Smilax china root was 1.51-1.91 times higher than that of 4% Smilax china root during fermentation. Meanwhile, ABTS free-radical scavenging capacity was enhanced up to 95.07 and 99.35% for 2% and 4% Smilax china root, respectively. Results from our study propose that bioactive components in Smilax China root were highly extracted by fermentation followed by saccharification and ethanol production, resulting in enhanced free-radical scavenging capacity. © 2013 Society of Chemical Industry. © 2013 Society of Chemical Industry.

  4. Kinetics of Several Oxygen-Containing Carbon-Centered Free Radical Reactions with Nitric Oxide.

    Science.gov (United States)

    Rissanen, Matti P; Ihlenborg, Marvin; Pekkanen, Timo T; Timonen, Raimo S

    2015-07-16

    Kinetics of four carbon-centered, oxygen-containing free radical reactions with nitric oxide (NO) were investigated as a function of temperature at a few Torr pressure of helium, employing flow tube reactors coupled to a laser-photolysis/resonance-gas-discharge-lamp photoionization mass spectrometer (LP-RPIMS). Rate coefficients were directly determined from radical (R) decay signals under pseudo-first-order conditions ([R]0 ≪ [NO]). The obtained rate coefficients showed negative temperature dependences, typical for a radical-radical association process, and can be represented by the following parametrizations (all in units of cm(3) molecule(-1) s(-1)): k(CH2OH + NO) = (4.76 × 10(-21)) × (T/300 K)(15.92) × exp[50700/(RT)] (T = 266-363 K, p = 0.79-3.44 Torr); k(CH3CHOH + NO) = (1.27 × 10(-16)) × (T/300 K)(6.81) × exp[28700/(RT)] (T = 241-363 K, p = 0.52-3.43 Torr); k(CH3OCH2 + NO) = (3.58 ± 0.12) × 10(-12) × (T/300 K)(-3.17±0.14) (T = 221-363 K, p = 0.50-0.80 Torr); k(T)3 = 9.62 × 10(-11) × (T/300 K)(-5.99) × exp[-7100/(RT)] (T = 221-473 K, p = 1.41-2.95 Torr), with the uncertainties given as standard errors of the fits and the overall uncertainties estimated as ±20%. The rate of CH3OCH2 + NO reaction was measured in two density ranges due to its observed considerable pressure dependence, which was not found in the studied hydroxyalkyl reactions. In addition, the CH3CO + NO rate coefficient was determined at two temperatures resulting in k298K(CH3CO + NO) = (5.6 ± 2.8) × 10(-13) cm(3) molecule(-1) s(-1). No products were found during these experiments, reasons for which are briefly discussed.

  5. Biological activity of clovers - free radical scavenging ability and antioxidant action of six Trifolium species.

    Science.gov (United States)

    Kolodziejczyk-Czepas, Joanna; Nowak, Pawel; Kowalska, Iwona; Stochmal, Anna

    2014-10-01

    Clovers were chosen on the basis of traditional medicine recommendations, agricultural value, or available information on their promising chemical profiles. This study evaluates and compares free radical scavenging and antioxidant properties of six clover species: Trifolium alexandrinum L. (Leguminosae), Trifolium fragiferum L., Trifolium hybridum L., Trifolium incarnatum L., Trifolium resupinatum var. majus Boiss., and Trifolium resupinatum var. resupinatum L. Free radical scavenging activity of the extracts (1.5-50 µg/ml) was estimated by reduction of 1,1-diphenyl-2-picrylhydrazyl (DPPH(•)) and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic) acid (ABTS(•)) radicals. The Trifolium extract effects on total antioxidant capacity of blood plasma were determined by the reduction of ABTS(•+) and DPPH(•) radicals, as well as with the use of the ferric reducing ability of plasma (FRAP) assay. The UPLC analysis of chemical profiles of the examined extracts showed the presence of three or four groups of phenolic substances, including phenolic acids, clovamides, isoflavones, and other flavonoids. The measurements of free radical scavenging and ferric reducing ability of the examined clover extracts revealed the strongest effect for T. alexandrinum. Furthermore, antioxidant activity assays in human plasma have shown protective effects of all extracts against peroxynitrite-induced reduction of total antioxidant capacity. Trifolium plants may be a rich source of bioactive substances with antioxidant properties. The examined extracts displayed free radical scavenging action and partly protected blood plasma against peroxynitrite-induced oxidative stress; however, the beneficial effects of T. alexandrinum and T. incarnatum seem to be slightly higher.

  6. In vivo imaging of free radicals produced by multivitamin-mineral supplements

    Science.gov (United States)

    Buettner, Garry R.; Fink, Bruno

    2015-01-01

    Background Redox active minerals in dietary supplements can catalyze unwanted and potentially harmful oxidations. Methods To determine if this occurs in vivo we employed electron paramagnetic (EPR) imaging. We used 1-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine (CPH) as a reporter for one-electron oxidations, e.g. free radical-mediated oxidations; the one-electron oxidation product of CPH, 3-carboxy-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (CP•), is a nitroxide free radical that is relatively persistent in vivo and detectable by EPR. As model systems, we used research formulations of vitamin mineral supplements (RVM) that are typical of commercial products. Results In in vitro experiments, upon suspension of RVM in aqueous solution, we observed: (1) the uptake of oxygen in the solution, consistent with oxidation of the components in the RVM; (2) the ascorbate free radical, a real-time indicator of ongoing oxidations; and (3) when amino acid/oligosaccharide (AAOS; glycinate or aspartate with non-digestible oligofructose) served as the matrix in the RVM, the rate of oxidation was significantly slowed. In a murine model, EPR imaging showed that the ingestion of RVM along with CPH results in the one-electron oxidation of CPH by RVM in the digestive system. The resulting CP• distributes throughout the body. Inclusion of AAOS in the RVM formulation diminished the oxidation of CPH to CP• in vivo. Conclusions These data demonstrate that typical formulations of multivitamin/multimineral dietary supplements can initiate the oxidation of bystander substances and that AAOS-complexes of essential redox active metals, e.g. copper and iron, have reduced ability to catalyze free radical formation and associated detrimental oxidations when a part of a multivitamin/multimineral formulation. PMID:26705481

  7. Mechanism of free radical generation in platelets and primary hepatocytes: A novel electron spin resonance study.

    Science.gov (United States)

    Wang, Chiun-Lang; Yang, Po-Sheng; Tsao, Jeng-Ting; Jayakumar, Thanasekaran; Wang, Meng-Jiy; Sheu, Joen-Rong; Chou, Duen-Suey

    2018-01-01

    Oxygen free radicals have been implicated in the pathogenesis of toxic liver injury and are thought to be involved in cardiac dysfunction in the cirrhotic heart. Therefore, direct evidence for the electron spin resonance (ESR) detection of how D‑galactosamine (GalN), an established experimental hepatotoxic substance, induced free radicals formation in platelets and primary hepatocytes is presented in the present study. ESR results demonstrated that GalN induced hydroxyl radicals (OH•) in a resting human platelet suspension; however, radicals were not produced in a cell free Fenton reaction system. The GalN‑induced OH• formation was significantly inhibited by the cyclooxygenase (COX) inhibitor indomethasin, though it was not affected by the lipoxygenase (LOX) or cytochrome P450 inhibitors, AA861 and 1‑aminobenzotriazole (ABT), in platelets. In addition, the present study demonstrated that baicalein induced semiquinone free radicals in platelets, which were significantly reduced by the COX inhibitor without affecting the formed OH•. In the mouse primary hepatocytes, the formation of arachidonic acid (AA) induced carbon‑centered radicals that were concentration dependently enhanced by GalN. These radicals were inhibited by AA861, though not affected by indomethasin or ABT. In addition, GalN did not induce platelet aggregation prior to or following collagen pretreatment in human platelets. The results of the present study indicated that GalN and baicalein may induce OH• by COX and LOX in human platelets. GalN also potentiated AA induced carbon‑centered radicals in hepatocytes via cytochrome P450. The present study presented the role of free radicals in the pathophysiological association between platelets and hepatocytes.

  8. Influence of Cocoa Flavanols and Procyanidins on Free Radical-induced Human Erythrocyte Hemolysis

    Directory of Open Access Journals (Sweden)

    Qin Yan Zhu

    2005-01-01

    Full Text Available Cocoa can be a rich source of antioxidants including the flavan-3-ols, epicatechin and catechin, and their oligomers (procyanidins. While these flavonoids have been reported to reduce the rate of free radical-induced erythrocyte hemolysis in experimental animal models, little is known about their effect on human erythrocyte hemolysis. The major objective of this work was to study the effect of a flavonoid-rich cocoa beverage on the resistance of human erythrocytes to oxidative stress. A second objective was to assess the effects of select purified cocoa flavonoids, epicatechin, catechin, the procyanidin Dimer B2 and one of its major metabolites, 3ʹ-O-methyl epicatechin, on free radical-induced erythrocyte hemolysis in vitro. Peripheral blood was obtained from 8 healthy subjects before and 1, 2, 4 and 8 h after consuming a flavonoid-rich cocoa beverage that provided 0.25 g/kg body weight (BW, 0.375 or 0.50 g/kg BW of cocoa. Plasma flavanol and dimer concentrations were determined for each subject. Erythrocyte hemolysis was evaluated using a controlled peroxidation reaction. Epicatechin, catechin, 3ʹ-O-methyl epicatechin and (--epicatechin-(4β > 8epicatechin (Dimer B2 were detected in the plasma within 1 h after the consumption of the beverage. The susceptibility of erythrocytes to hemolysis was reduced significantly following the consumption of the beverages. The duration of the lag time, which reflects the capacity of cells to buffer free radicals, was increased. Consistent with the above, the purified flavonoids, epicatechin, catechin, Dimer B2 and the metabolite 3ʹ-O-methyl epicatechin, exhibited dose-dependent protection against AAPH-induced erythrocyte hemolysis at concentrations ranging from 2.5 to 20 μM. Erythrocytes from subjects consuming flavonoid-rich cocoa show reduced susceptibility to free radical-induced hemolysis (p < 0.05.

  9. Radioprotective effects of Asparagus racemosus extracts against free radical damage in rat liver mitochondria

    International Nuclear Information System (INIS)

    Boloor, K.K.; Kamat, J.P.; Devasagayam, T.P.A.; Venkatachalam, S.R.

    2000-01-01

    The possible antioxidant effect of the extracts of Asparagus racemosus against membrane damage induced by free radicals generated during γ-radiation was examined in rat liver/brain mitochondria. These extracts displayed significant antioxidant properties in mitochondria against oxidation of both lipids and proteins as assessed by lipid peroxidation, protein oxidation and depletion of thiols. The inhibitory effect of the extracts, rich in polysaccharides like galactose, was more than that of the established antioxidants glutathione and ascorbic acid. (author)

  10. Evaluation by electronic paramagnetic resonance of the number of free radicals produced in irradiated rat bone

    International Nuclear Information System (INIS)

    Marble, G.; Valderas, R.

    1966-01-01

    The number of long half-life free radicals created by gamma irradiation in the bones of the rat has been determined from the electrons paramagnetic resonance spectrum. This number decreases slowly with time (calculated half life: 24 days). It is proportional to the dose of gamma radiation given to the rat. The method could find interesting applications in the field of biological dosimetry. (authors) [fr

  11. Occupational exposure to ionizing radiation as a risk factor for free-radicals mediated diseases

    International Nuclear Information System (INIS)

    Djurovic, B.; Spasic-Jokic, V.; Selakovic, V.

    2007-01-01

    Complete text of publication follows. It was experimentally showed, that the exposure to low doses of ionizing radiation (IR) result in over-production of oxygen derived free radicals with inverse dose-rate effect. The oxidative stress that follows, especially cell membrane damage, was considered by Petkau, as crucial step in the induction of radiation injuries. From clinical research and practice with other unexposed patients is known that this type of cell damage can lead to an impairment of cellular function and can cause many free-radicals mediated diseases, such as atherosclerosis, damage of heart muscles, inflammatory and immuno-reactive lesions, senile dementia, cancer, etc. The aim of this paper is to investigate if occupational exposure to low doses of IR change the redox status of exposed personnel, and if so, is it the additional risk factor for free-radicals mediated diseases. Subjects: 77 medical workers, devided in two groups: 44 occupationally exposed to ionizing radiation (E), and 33 controls (C), matched in age, gender, habits-daitary, alcohol consumption, smoking and exposure time, were examined. Methods: Radiation dose accumulated over years was calculated on the basis of individual TL-dose records. Superoxide-anion and MDA production, as well as SOD (MnSOD, CuZnSOD) and GSH activity were determined in blood samples spectrophotometrically. Results: Significantly higher incidence of cataract, and higher, but not significant, incidence of cardiovascular diseases was noticed in exposed. Our results also confirmed significantly higher superoxide and MDA production (p=0.0049, 0.000028, respectively), as well as, increased activity of MnSOD and CuZnSOD (p0.0105, 0.001, respectively), and decreased level of GSH (p=0.0599) in exposed. Conclusions: Our results showed that low doses of IR could induce oxidative stress and for that reason could be considered as additional risk factor for free radical-mediated diseases. Further epidemiological studies are

  12. Synthesis, X-ray crystallography, spectroscopic characterization and spectroscopic/electrochemical evidence of formation of phenoxy free radical in active center analogs of galactose oxidase - [Cu(Salgly)H₂O] and [Cu(Salphenylalanine)H₂O].

    Science.gov (United States)

    Das, Biva; Medhi, Okhil K

    2013-03-01

    The formation of phenolate free radical is the factor of high turnover for catalytic activity of galactose oxidase (GO) compared to that by inorganic complexes. A new active center analog of GO, [Cu(II)(Salphenylalanine)H(2)O] have been synthesized and its single crystal X-ray analysis was done. In aqueous surfactant micellar solution chemical oxidation as well as electrochemical oxidation of structural models of galactose oxidase - [Cu(II)Salgly·H(2)O] and [Cu(II)(Salphenylalanine)·H(2)O], have been found to generate free radical originating at the phenolate group. Formation of the free radical have been proved by electron paramagnetic resonance spectroscopy, electronic spectroscopy and electrochemistry. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Double trouble at high density:

    DEFF Research Database (Denmark)

    Gergs, André; Palmqvist, Annemette; Preuss, Thomas G

    2014-01-01

    Population size is often regulated by negative feedback between population density and individual fitness. At high population densities, animals run into double trouble: they might concurrently suffer from overexploitation of resources and also from negative interference among individuals...... regardless of resource availability, referred to as crowding. Animals are able to adapt to resource shortages by exhibiting a repertoire of life history and physiological plasticities. In addition to resource-related plasticity, crowding might lead to reduced fitness, with consequences for individual life...... history. We explored how different mechanisms behind resource-related plasticity and crowding-related fitness act independently or together, using the water flea Daphnia magna as a case study. For testing hypotheses related to mechanisms of plasticity and crowding stress across different biological levels...

  14. A Free-Radical Pathway to Hydrogenated Phenanthrene in Molecular Clouds-Low Temperature Growth of Polycyclic Aromatic Hydrocarbons.

    Science.gov (United States)

    Thomas, Aaron M; Lucas, Michael; Yang, Tao; Kaiser, Ralf I; Fuentes, Luis; Belisario-Lara, Daniel; Mebel, Alexander M

    2017-08-05

    The hydrogen-abstraction/acetylene-addition mechanism has been fundamental to unravelling the synthesis of polycyclic aromatic hydrocarbons (PAHs) detected in combustion flames and carbonaceous meteorites like Orgueil and Murchison. However, the fundamental reaction pathways accounting for the synthesis of complex PAHs, such as the tricyclic anthracene and phenanthrene along with their dihydrogenated counterparts, remain elusive to date. By investigating the hitherto unknown chemistry of the 1-naphthyl radical with 1,3-butadiene, we reveal a facile barrierless synthesis of dihydrophenanthrene adaptable to low temperatures. These aryl-type radical additions to conjugated hydrocarbons via resonantly stabilized free-radical intermediates defy conventional wisdom that PAH growth is predominantly a high-temperature phenomenon and thus may represent an overlooked path to PAHs as complex as coronene and corannulene in cold regions of the interstellar medium like in the Taurus Molecular Cloud. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. SIMULTANEOUS MEASUREMENT OF FREE RADICAL DECAY IN POLYMERIZATION OF MMA INITIATED BY AIBN USING ESR AND ITS KINETIC MODEL

    Institute of Scientific and Technical Information of China (English)

    Ping Xia; Qing-song Hu; Xiao-lan Qian; Xul-in Jiang; De-yue Yan

    2001-01-01

    The kinetics of free radical decay in the polymerization of MMA initiated by AIBN was studied by means of ESR spectroscopy. It was found that the curves of radical decay are strongly associated with the reaction temperature, the initiator concentration and the solvent. In the case of the radical polymerization carried out at high temperature or in solution, the radical concentration first reached a maximum, then declined monotonously with reaction time. It was also found that the greater the amount of initiator or the higher the temperature, the more rapidly the radicals decay. When the bulk polymerization was implemented at a relatively low temperature, the curves of radical decay became more complicated, i.e.,the radical concentration rapidly rose to a maximum, then dropped to a minimum, finally increased again with reaction time.Taking into account the diffusion effect, a semi-empirical equation is suggested to describe the kinetics of propagating radical decay.

  16. EPR of free radicals in solids II trends in methods and applications

    CERN Document Server

    Lund, Anders; Lund, Anders

    2012-01-01

    EPR of Free Radicals in Solids: Trends in Methods and Applications, 2nd ed. presents a critical two volume review of the methods and applications of EPR (ESR) for the study of free radical processes in solids. Emphasis is on the progress made in the developments in EPR technology, in the application of sophisticated matrix isolation techniques and in the advancement in quantitative EPR that have occurred since the 1st edition was published. Improvements have been made also at theoretical level, with the development of methods based on first principles and their application to the calculation of magnetic properties as well as in spectral simulations. EPR of Free Radicals in Solids II focuses on the trends in applications of experimental and theoretical methods to extract structural and dynamical properties of radicals and spin probes in solid matrices by continuous wave (CW) and pulsed techniques in nine chapters written by experts in the field. It examines the studies involving radiation- and photo-induced in...

  17. Microwave Saturation of Complex EPR Spectra and Free Radicals of Burnt Skin Treated with Apitherapeutic Agent

    Directory of Open Access Journals (Sweden)

    Pawel Olczyk

    2013-01-01

    Full Text Available The effect of microwave power on the complex electron paramagnetic resonance spectra of the burn matrix after the therapy with propolis was examined. The spectra were measured with microwaves in the range of 2.2–79 mW. Three groups of free radicals were found in the damaged skin samples. Their spectral lines evolve differently with the microwave power. In order to detect these free radical groups, the lineshape of the spectra was numerically analysed. The spectra were a superposition of three component lines. The best fit was obtained for the deconvolution of the experimental spectra into one Gauss and two Lorentz lines. The microwave power changes also the lineshape of the spectra of thermally injured skin treated with the conventional agent—silver sulphadiazine. The spectral changes were different for propolis and for silver sulphadiazine. The number of individual groups of free radicals in the wound bed after implementation of these two substances is not equal. It may be explained by a higher activity of propolis than of silver sulphadiazine as therapeutic agents.

  18. Muon level crossing resonance spectroscopy applied to free-radical formation

    International Nuclear Information System (INIS)

    Venkateswaran, K.; Barnabas, M.V.; Walker, D.C.

    1989-01-01

    Muon Level Crossing Resonance Spectroscopy has been used to explore two aspects of muonium chemistry: unique free radicals and muonated radical yields. (1) A variety of new free-radicals have been seen by LCR. For instance, in thioacetamide the only radical produced from muonium is the S sm-bullet radical formed when Mu adds to the C of the C=S bond. In allylbenzene a whole range of radicals form with substantial yields (two side-chain and three ring additions); whereas in styrene, 85% of the radicals have Mu bonded to the end C of the side-chain and there is no meta-adduct at all. (2) Absolute yields of the radicals formed by interaction of muonium atoms in water with acrylamide as a solute (and with benzene in n-hexane) have shown that all muons not directly incorporated into diamagnetic molecules (such as MuH) appear as muonated free radicals. i.e. the missing fraction is found

  19. Evaluation of Both Free Radical Scavenging Capacity and Antioxidative Damage Effect of Polydatin.

    Science.gov (United States)

    Jin, Ju; Li, Yan; Zhang, Xiuli; Chen, Tongsheng; Wang, Yifei; Wang, Zhiping

    Cellular damage such as oxidation and lipid peroxidation, and DNA damage induced by free-radicals like reactive oxygen species, has been implicated in several diseases. Radicals generated by 2,2-azobis (2-amidino-propane) dihydrochloride (AAPH) are similar to physiologically active ones. In this study we found that polydatin, a resveratrol natural precursor derived from many sources, has the capacity of free radical scavenging and antioxidative damage. Using free radical scavenging assays, the IC50 values of polydatin were 19.25 and 5.29 μg/ml with the DPPH and the ABTS assay, respectively, and 0.125 mg ferrous sulfate/1 mg polydatin with the FRAP assay. With the AAPH-induced oxidative injury cell model assay, polydatin showed a strong protective effect against the human liver tumor HepG2 cell oxidative stress damage. These results indicate that the antioxidant properties of polydatin have great potential for use as an alternative to more toxic synthetic antioxidants as an additive in food, cosmetics and pharmaceutical preparations for the treatment of oxidative diseases.

  20. Increase in the free radical scavenging capability of bitter gourd by a heat-drying process.

    Science.gov (United States)

    Wei, Lu; Shaoyun, Wang; Shutao, Liu; Jianwu, Zhou; Lijing, Ke; Pingfan, Rao

    2013-12-01

    Bitter gourd (Momordica charantia Linn.) is widely regarded as one of the best remedy foods for diabetes. The positive effect of bitter gourd on diabetes has been attributed in part to the remarkable free radical scavenging activity of its boiled water extract from sun-dried fruits. It is well known that a heat process significantly influences the antioxidant activity of fresh fruits. However, the heat drying processes of bitter gourd have not been studied so far. Here, we show that the free radical scavenging capability of bitter gourd extract significantly increases after the heat drying process, while the content of flavonoids and phenols, which are generally regarded as the main antioxidant components in bitter gourd, remain unaffected. Furthermore, the content of free amino acids and the total reducing sugar were found to decrease with increasing browning index, indicating the progression of the Maillard reaction, products of which are known to possess significant antioxidant activity. Therefore, it suggests that Maillard reaction products may be the main contributors to the increase in antioxidant capability. Finally, the bitter gourd extract with the higher antioxidant activity, was shown to manifest a corresponding higher proliferation activity on NIT-1 beta-cells. These results suggest that controllable conditions in the heat-drying processing of fresh bitter gourd fruit is of significance for enhancing the total free radical scavenging capacity, beta-cell proliferation activity and possibly the anti-diabetic activity of this fruit.

  1. Quantitative investigation of free radicals in bio-oil and their potential role in condensed-phase polymerization.

    Science.gov (United States)

    Kim, Kwang Ho; Bai, Xianglan; Cady, Sarah; Gable, Preston; Brown, Robert C

    2015-03-01

    We report on the quantitative analysis of free radicals in bio-oils produced from pyrolysis of cellulose, organosolv lignin, and corn stover by EPR spectroscopy. Also, we investigated their potential role in condensed-phase polymerization. Bio-oils produced from lignin and cellulose show clear evidence of homolytic cleavage reactions during pyrolysis that produce free radicals. The concentration of free radicals in lignin bio-oil was 7.5×10(20)  spin g(-1), which was 375 and 138 times higher than free-radical concentrations in bio-oil from cellulose and corn stover. Pyrolytic lignin had the highest concentration in free radicals, which could be a combination of carbon-centered (benzyl radicals) and oxygen-centered (phenoxy radicals) organic species because they are delocalized in a π system. Free-radical concentrations did not change during accelerated aging tests despite increases in molecular weight of bio-oils, suggesting that free radicals in condensed bio-oils are stable. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Electrochemical behavior of free-radical derivatives of tetra(4hydroxyl-3,5-di-tert-butylphenyl) porphyrin

    Energy Technology Data Exchange (ETDEWEB)

    Pokhodenko, V.D.; Melezhik, A.V.; Platonova, E.P.; Vovk, D.N.

    1984-08-01

    The electrochemical behavior of free-radical derivatives of tetra(4hydroxyl-3,5-di-tert-butylphenyl) porphyrins and their complexes with Mg(II), Zn(II), Ni(II), CU(II), and Pd(II) ions was studied by the methods of voltamperometry, ESR, and spectrophotometry. It was shown that the introduction of free-radical substituents into the porphin macrocycle leads to a substantial decrease in the oxidation and reduction potentials of the complexes. The degree of conjunction of substituents with the porphin macrocycle is estimated according to the difference of the redox potentials of free-radical and quinoid derivatives of metalloporphyrins.

  3. Free radical generation induced by ultrasound in red wine and model wine: An EPR spin-trapping study

    OpenAIRE

    Zhang, Quing An; Shen, Yuan; Fan, Xue-Hui; García-Martín, Juan Francisco; Wang, Xi; Song, Yun

    2015-01-01

    © 2015 Published by Elsevier B.V. Direct evidence for the formation of 1-hydroxylethyl radicals by ultrasound in red wine and air-saturated model wine is presented in this paper. Free radicals are thought to be the key intermediates in the ultrasound processing of wine, but their nature has not been established yet. Electron paramagnetic resonance (EPR) spin trapping with 5,5-dimethyl-l-pyrrolin N-oxide (DMPO) was used for the detection of hydroxyl free radicals and 1-hydroxylethyl free radic...

  4. A novel property of gold nanoparticles: Free radical generation under microwave irradiation

    International Nuclear Information System (INIS)

    Paudel, Nava Raj; Shvydka, Diana; Parsai, E. Ishmael

    2016-01-01

    Purpose: Gold nanoparticles (GNPs) are known to be effective mediators in microwave hyperthermia. Interaction with an electromagnetic field, large surface to volume ratio, and size quantization of nanoparticles (NPs) can lead to increased cell killing beyond pure heating effects. The purpose of this study is to explore the possibility of free radical generation by GNPs in aqueous media when they are exposed to a microwave field. Methods: A number of samples with 500 mM 5,5-dimethyl-1-pyrroline N-oxide (DMPO) in 20 ppm GNP colloidal suspensions were scanned with an electron paramagnetic resonance (EPR)/electron spin resonance spectrometer to generate and detect free radicals. A fixed (9.68 GHz) frequency microwave from the spectrometer has served for both generation and detection of radicals. EPR spectra obtained as first derivatives of intensity with the spectrometer were double integrated to get the free radical signal intensities. Power dependence of radical intensity was studied by applying various levels of microwave power (12.5, 49.7, and 125 mW) while keeping all other scan parameters the same. Free radical signal intensities from initial and final scans, acquired at the same power levels, were compared. Results: Hydroxyl radical (OH⋅) signal was found to be generated due to the exposure of GNP–DMPO colloidal samples to a microwave field. Intensity of OH⋅ signal thus generated at 12.5 mW microwave power for 2.8 min was close to the intensity of OH⋅ signal obtained from a water–DMPO sample exposed to 1.5 Gy ionizing radiation dose. For repeated scans, higher OH⋅ intensities were observed in the final scan for higher power levels applied between the initial and the final scans. Final intensities were higher also for a shorter time interval between the initial and the final scans. Conclusions: Our results observed for the first time demonstrate that GNPs generate OH⋅ radicals in aqueous media when they are exposed to a microwave field. If OH

  5. A novel property of gold nanoparticles: Free radical generation under microwave irradiation.

    Science.gov (United States)

    Paudel, Nava Raj; Shvydka, Diana; Parsai, E Ishmael

    2016-04-01

    Gold nanoparticles (GNPs) are known to be effective mediators in microwave hyperthermia. Interaction with an electromagnetic field, large surface to volume ratio, and size quantization of nanoparticles (NPs) can lead to increased cell killing beyond pure heating effects. The purpose of this study is to explore the possibility of free radical generation by GNPs in aqueous media when they are exposed to a microwave field. A number of samples with 500 mM 5,5-dimethyl-1-pyrroline N-oxide (DMPO) in 20 ppm GNP colloidal suspensions were scanned with an electron paramagnetic resonance (EPR)/electron spin resonance spectrometer to generate and detect free radicals. A fixed (9.68 GHz) frequency microwave from the spectrometer has served for both generation and detection of radicals. EPR spectra obtained as first derivatives of intensity with the spectrometer were double integrated to get the free radical signal intensities. Power dependence of radical intensity was studied by applying various levels of microwave power (12.5, 49.7, and 125 mW) while keeping all other scan parameters the same. Free radical signal intensities from initial and final scans, acquired at the same power levels, were compared. Hydroxyl radical (OH⋅) signal was found to be generated due to the exposure of GNP-DMPO colloidal samples to a microwave field. Intensity of OH⋅ signal thus generated at 12.5 mW microwave power for 2.8 min was close to the intensity of OH⋅ signal obtained from a water-DMPO sample exposed to 1.5 Gy ionizing radiation dose. For repeated scans, higher OH⋅ intensities were observed in the final scan for higher power levels applied between the initial and the final scans. Final intensities were higher also for a shorter time interval between the initial and the final scans. Our results observed for the first time demonstrate that GNPs generate OH⋅ radicals in aqueous media when they are exposed to a microwave field. If OH⋅ radicals can be generated close to

  6. A novel property of gold nanoparticles: Free radical generation under microwave irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Paudel, Nava Raj, E-mail: nrpaudel@yahoo.com [Department of Radiation Oncology, The University of Toledo Medical Center, Toledo, Ohio 43614 and Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205 (United States); Shvydka, Diana; Parsai, E. Ishmael [Department of Radiation Oncology, The University of Toledo Medical Center, Toledo, Ohio 43614 (United States)

    2016-04-15

    Purpose: Gold nanoparticles (GNPs) are known to be effective mediators in microwave hyperthermia. Interaction with an electromagnetic field, large surface to volume ratio, and size quantization of nanoparticles (NPs) can lead to increased cell killing beyond pure heating effects. The purpose of this study is to explore the possibility of free radical generation by GNPs in aqueous media when they are exposed to a microwave field. Methods: A number of samples with 500 mM 5,5-dimethyl-1-pyrroline N-oxide (DMPO) in 20 ppm GNP colloidal suspensions were scanned with an electron paramagnetic resonance (EPR)/electron spin resonance spectrometer to generate and detect free radicals. A fixed (9.68 GHz) frequency microwave from the spectrometer has served for both generation and detection of radicals. EPR spectra obtained as first derivatives of intensity with the spectrometer were double integrated to get the free radical signal intensities. Power dependence of radical intensity was studied by applying various levels of microwave power (12.5, 49.7, and 125 mW) while keeping all other scan parameters the same. Free radical signal intensities from initial and final scans, acquired at the same power levels, were compared. Results: Hydroxyl radical (OH⋅) signal was found to be generated due to the exposure of GNP–DMPO colloidal samples to a microwave field. Intensity of OH⋅ signal thus generated at 12.5 mW microwave power for 2.8 min was close to the intensity of OH⋅ signal obtained from a water–DMPO sample exposed to 1.5 Gy ionizing radiation dose. For repeated scans, higher OH⋅ intensities were observed in the final scan for higher power levels applied between the initial and the final scans. Final intensities were higher also for a shorter time interval between the initial and the final scans. Conclusions: Our results observed for the first time demonstrate that GNPs generate OH⋅ radicals in aqueous media when they are exposed to a microwave field. If OH

  7. Inhibition of platelet aggregation and in vitro free radical scavenging activity of dried fruiting bodies of Pleurotus eous.

    Science.gov (United States)

    Suseem, S R; Saral, Mary

    2015-07-01

    To evaluate the ethyl acetate, methanol and aqueous extracts of dried fruiting bodies of Pleurotus eous for its anti-platelet activity on human volunteer's blood. And also to analyze the free radical scavenging property of the extracts of P.eous by using various in vitro models. Anti-platelet activity of dried fruiting bodies of P.eous was evaluated by in vitro model using blood platelets. Inhibition of platelet aggregation was monitored after pre-incubation of platelets with the crude extracts of mushroom P.eous. Antioxidant activities of extracts of P.eous were evaluated by different in vitro experiments, namely, 1, 1-diphenyl-2-picryl hydrazyl (DPPH), superoxide, hydroxyl radical and lipid peroxide radical models. Crude extracts of mushroom P.eous inhibited platelet aggregation dose-dependently which was induced by adenosine diphosphate (ADP). At a maximum concentration of 10 mg/mL, methanol extract effected 64.02% inhibition of lipid per-oxidation and 50.12% scavenging effect on superoxide anion radical. Aqueous extract of P.eous have shown 69.43% chelating ability on ferrous ions, 24.27% scavenging effect on hydroxyl radical and 49.57% scavenging effect on DPPH radical at 10 mg/mL. Increasing concentrations of the extract were found to cause progressively decreasing of the intensity of absorbance. Anti-platelet effects could be related in part to the polyphenolic compounds present in the extracts. Antioxidant activity results indicated the free radical scavenging property of the extracts of P.eous which might be due to the high content of phenolic compounds and flavonoids.

  8. The Synthesis and Evaluation of Novel Hydroxyl Substituted Chalcone Analogs with in Vitro Anti-Free Radicals Pharmacological Activity and in Vivo Anti-Oxidation Activity in a Free Radical-Injury Alzheimer’s Model

    Directory of Open Access Journals (Sweden)

    Ying Pan

    2013-01-01

    Full Text Available Alzheimer’s disease (AD pathogenesis involves an imbalance between free radical formation and destruction. In order to obtain a novel preclinical anti-AD drug candidate, we synthesized a series of novel hydroxyl chalcone analogs which possessed anti-free radical activity, and screened their effects on scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH and OH free radicals in vitro. Compound C7, 4,2'-dihydroxy-3,5-dimethoxychalcone was found to have potent activity in these anti-free radical activity tests. Further research revealed that C7 could elevate glutathione peroxidase (GSH-PX and super oxide dismutase (SOD levels and lower malonaldehyde (MDA level in vivo in the Alzheimer’s model. The indication of C7’s effect on AD needs further study.

  9. Environmentally persistent free radicals inhibit cytochrome P450 activity in rat liver microsomes

    Energy Technology Data Exchange (ETDEWEB)

    Reed, James R., E-mail: rreed@lsuhsc.edu [Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Science Center, 533 Bolivar St., New Orleans, LA 70112 (United States); The Stanley S. Scott Cancer Center, Louisiana State University Health Science Center, 533 Bolivar St., New Orleans, LA 70112 (United States); Cawley, George F.; Ardoin, Taylor G. [Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Science Center, 533 Bolivar St., New Orleans, LA 70112 (United States); The Stanley S. Scott Cancer Center, Louisiana State University Health Science Center, 533 Bolivar St., New Orleans, LA 70112 (United States); Dellinger, Barry; Lomnicki, Slawomir M.; Hasan, Farhana; Kiruri, Lucy W. [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States); Backes, Wayne L. [Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Science Center, 533 Bolivar St., New Orleans, LA 70112 (United States); The Stanley S. Scott Cancer Center, Louisiana State University Health Science Center, 533 Bolivar St., New Orleans, LA 70112 (United States)

    2014-06-01

    Combustion processes generate particulate matter that affects human health. When incineration fuels include components that are highly enriched in aromatic hydrocarbons (especially halogenated varieties) and redox-active metals, ultrafine particulate matter containing air-stable, environmentally persistent free radicals (EPFRs) is generated. The exposure to fine EPFRs (less than 2.5 μm in diameter) has been shown to negatively influence pulmonary and cardiovascular functions in living organisms. The goal of this study was to determine if these EPFRs have a direct effect on cytochrome P450 function. This was accomplished by direct addition of the EPFRs to rat liver microsomal preparations and measurement of several P450 activities using form-selective substrates. The EPFRs used in this study were formed by heating vapors from an organic compound (either monochlorophenol (MCP230) or 1,2-dichlorobenzene (DCB230)) and 5% copper oxide supported on silica (approximately 0.2 μm in diameter) to 230 °C under vacuum. Both types of EPFRs (but not silica, physisorbed silica, or silica impregnated with copper oxide) dramatically inhibited the activities of CYP1A, CYP2B, CYP2E1, CYP2D2 and CYP3A when incubated at concentrations less than 0.1 mg/ml with microsomes and NADPH. Interestingly, at the same concentrations, the EPFRs did not inhibit HO-1 activity or the reduction of cytochrome c by NADPH-cytochrome P450 reductase. CYP2D2-selective metabolism by rat liver microsomes was examined in more detail. The inhibition of CYP2D2-selective metabolism by both DCB230- and MCP230-EPFRs appeared to be largely noncompetitive and was attenuated in the presence of catalase suggesting that reactive oxygen species may be involved in the mechanism of inhibition. - Highlights: • Combustion of organic pollutants generates long-lived particulate radicals (EPFRs). • EPFRs inhibit metabolism by all cytochromes P450 tested in rat liver microsomes. • EPFR-mediated inhibition is related to

  10. Environmentally persistent free radicals inhibit cytochrome P450 activity in rat liver microsomes

    International Nuclear Information System (INIS)

    Reed, James R.; Cawley, George F.; Ardoin, Taylor G.; Dellinger, Barry; Lomnicki, Slawomir M.; Hasan, Farhana; Kiruri, Lucy W.; Backes, Wayne L.

    2014-01-01

    Combustion processes generate particulate matter that affects human health. When incineration fuels include components that are highly enriched in aromatic hydrocarbons (especially halogenated varieties) and redox-active metals, ultrafine particulate matter containing air-stable, environmentally persistent free radicals (EPFRs) is generated. The exposure to fine EPFRs (less than 2.5 μm in diameter) has been shown to negatively influence pulmonary and cardiovascular functions in living organisms. The goal of this study was to determine if these EPFRs have a direct effect on cytochrome P450 function. This was accomplished by direct addition of the EPFRs to rat liver microsomal preparations and measurement of several P450 activities using form-selective substrates. The EPFRs used in this study were formed by heating vapors from an organic compound (either monochlorophenol (MCP230) or 1,2-dichlorobenzene (DCB230)) and 5% copper oxide supported on silica (approximately 0.2 μm in diameter) to 230 °C under vacuum. Both types of EPFRs (but not silica, physisorbed silica, or silica impregnated with copper oxide) dramatically inhibited the activities of CYP1A, CYP2B, CYP2E1, CYP2D2 and CYP3A when incubated at concentrations less than 0.1 mg/ml with microsomes and NADPH. Interestingly, at the same concentrations, the EPFRs did not inhibit HO-1 activity or the reduction of cytochrome c by NADPH-cytochrome P450 reductase. CYP2D2-selective metabolism by rat liver microsomes was examined in more detail. The inhibition of CYP2D2-selective metabolism by both DCB230- and MCP230-EPFRs appeared to be largely noncompetitive and was attenuated in the presence of catalase suggesting that reactive oxygen species may be involved in the mechanism of inhibition. - Highlights: • Combustion of organic pollutants generates long-lived particulate radicals (EPFRs). • EPFRs inhibit metabolism by all cytochromes P450 tested in rat liver microsomes. • EPFR-mediated inhibition is related to

  11. Kinetics of several oxygenated carbon-centered free radical reactions with NO2.

    Science.gov (United States)

    Rissanen, Matti P; Arppe, Suula L; Timonen, Raimo S

    2013-05-16

    Five oxygenated carbon-centered free radical reactions with nitrogen dioxide (NO2) have been studied in direct time-resolved measurements. Experiments were conducted in a temperature-controlled flow tube reactor coupled to a 193 nm exciplex laser photolysis and a resonance gas lamp photoionization mass spectrometer. Reactions were investigated under pseudofirst-order conditions, with the NO2 concentrations of the experiments in great excess over the initial radical concentrations ([R]0 CH3CO radical reactions with NO2 and, hence, includes the three smallest hydroxyalkyl radical species (CH2OH, CH2CH2OH, and CH3CHOH). The obtained rate coefficients are high with the temperature-dependent rate coefficients given by a formula k(T) = k300K × (T/300 K)(-n) as (in units of cm(3) molecule(-1) s(-1)): k(CH2OH + NO2) = (8.95 ± 2.70) × 10(-11) × (T/300 K)(-0.54±0.27) (T = 298-363 K), k(CH2CH2OH + NO2) = (5.99 ± 1.80) × 10(-11) × (T/300 K)(-1.49±0.45)(T = 241-363 K), k(CH3CHOH + NO2) = (7.48 ± 2.24) × 10(-11) × (T/300 K)(-1.36±0.41) (T = 266-363 K), k(CH3OCH2 + NO2) = (7.85 ± 2.36) × 10(-11) × (T/300 K)(-0.93±0.28) (T = 243-363 K), and k(CH3CO + NO2) = (2.87 ± 0.57) × 10(-11) × (T/300 K)(-2.45±0.49) (T = 241-363 K), where the uncertainties refer to the estimated overall uncertainties of the values obtained. The determined rate coefficients show negative temperature dependence with no apparent bath gas pressure dependence under the current experimental conditions (241-363 K and about 1-3 Torr helium). This behavior is typical for a radical-radical addition mechanism with no potential energy barrier above the energy of the separated reactants in the entrance channel of the reaction. Unfortunately the absence of detected product signals prevented gaining deeper insight into the reaction mechanism.

  12. PHOTOGENERATION OF SINGLET OXYGEN AND FREE RADICALS IN DISSOLVED ORGANIC MATTER ISOLATED FROM THE MISSISSIPPI AND ATCHAFALAYA RIVER PLUMES

    Science.gov (United States)

    The photoreactivity to UV light of ultrafiltered dissolved organic matter (DOM) collected during cruises along salinity transects in the Mississippi and Atchafalaya River plumes was examined by measuring photogenerated free radicals and singlet molecular oxygen (1O2) photosensiti...

  13. The ability of Abelmoschus manihot L. leaf extract in scavenging of free radical DPPH and total flavonoid determination

    Science.gov (United States)

    Sudewi, S.; Lolo, W. A.; Warongan, M.; Rifai, Y.; Rante, H.

    2017-11-01

    Abelmoschus manihot L. has reported to have flavonoids content. This study aims were to determine the ability of A. manihot extract in counteracting free radical DPPH and determine the content of total flavonoids. A. manihot leaf was taken from 2 regions in North Sulawesi, namely Tomohon and Kotamobagu. The maceration was carried out to extract the active compound in a 96% ethanol solvent. Free radical scavenging analysis was carried out by DPPH and determination of its total flavonoid in the extract was measured using spectrophotometri method. The results showed that A. manihot extract from Tomohon and Kotamobagu could counteract free radical of DPPH with value of free radical activity of 88.151 and 88.801 %, respectively. A. manihot leaf from Kotamobagu has higher total flavonoids content 61.763 mg/g compare to Tomohon 46.679 mg/g which presented as quercetin. A. manihot has antioxidant activity.

  14. Nuclear coupling of 33S and the nature of free radicals in irradiated crystals of N-acetyl-L-cysteine

    International Nuclear Information System (INIS)

    Hadley, J.H. Jr.; Gordy, W.

    1977-01-01

    Hyperfine structure due to 33 S in its natural abundance of 0.76% has been measured in the electron spin resonance of free radicals produced by x-irradiation of single crystals of N-acetyl-L-cysteine at 77 K. These measurements proved that the radicals produced at 77 K with principal g values of 1.990, 2.006, and 2.214 are monosulfide radicals with the 3p unpaired electron density of 0.70 on the S. They are believed to be negatively charged molecules RCH 2 S - H or neutral RCH 2 SH 2 radicals in which 90% of the spin density of the captured electron is concentrated in a d-p hybrid orbital on the S. As the temperature is raised to 300 0 K, these, as well as the carbon-centered radicals produced at the lower temperature, are mostly converted to neutral disulfide radicals RCH 2 SS like those observed in irradiated cysteine

  15. Studies on photofading and stable free radical formation in reactive dyed cellulosic systems under their exposure to light

    International Nuclear Information System (INIS)

    Remi, E.; Horvath, O.; Vig, A.; Aranyosi, P.; Rusznak, I.

    1996-01-01

    In light exposed systems of cotton and C.I. Reactive Red 3, C.I. Reactive Black 5 and C.I. Direct Blue 78 azo dyes respectively, generated stable free radicals could be detected. The observed hyperfine splitting of ESR spectra suggest the free radical are formed in the chromophore. Based upon the calculated g-values the location of the generated unpaired electron could be assumed on one of the C atoms of the dye molecule. (author)

  16. Free radical generation from an aniline derivative in HepG2 cells: a possible captodative effect.

    Science.gov (United States)

    Horinouchi, Yuya; Summers, Fiona A; Ehrenshaft, Marilyn; Mason, Ronald P

    2015-01-01

    Xenobiotic metabolism can induce the generation of protein radicals, which are believed to play an important role in the toxicity of chemicals and drugs. It is therefore important to identify chemical structures capable of inducing macromolecular free radical formation in living cells. In this study, we evaluated the ability of four structurally related environmental chemicals, aniline, nitrosobenzene, N,N-dimethylaniline, and N,N-dimethyl-4-nitrosoaniline (DMNA), to induce free radicals and cellular damage in the hepatoma cell line HepG2. Cytotoxicity was assessed using lactate dehydrogenase assays, and morphological changes were observed using phase contrast microscopy. Protein free radicals were detected by immuno-spin trapping using in-cell western experiments and confocal microscopy to determine the subcellular locale of free radical generation. DMNA induced free radical generation, lactate dehydrogenase release, and morphological changes in HepG2 cells, whereas aniline, nitrosobenzene, N,N-dimethylaniline did not. Confocal microscopy showed that DMNA induced free radical generation mainly in the cytosol. Preincubation of HepG2 cells with N-acetylcysteine and 2,2'-dipyridyl significantly prevented free radical generation on subsequent incubation with DMNA, whereas preincubation with apocynin and dimethyl sulfoxide had no effect. These results suggest that DMNA is metabolized to reactive free radicals capable of generating protein radicals which may play a critical role in DMNA toxicity. We propose that the captodative effect, the combined action of the electron-releasing dimethylamine substituent, and the electron-withdrawing nitroso substituent, leads to a thermodynamically stabilized radical, facilitating enhanced protein radical formation by DMNA. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Development of a new free radical absorption capacity assay method for antioxidants: aroxyl radical absorption capacity (ARAC).

    Science.gov (United States)

    Nagaoka, Shin-ichi; Nagai, Kanae; Fujii, Yuko; Ouchi, Aya; Mukai, Kazuo

    2013-10-23

    A new free radical absorption capacity assay method is proposed with use of an aroxyl radical (2,6-di-tert-butyl-4-(4'-methoxyphenyl)phenoxyl radical) and stopped-flow spectroscopy and is named the aroxyl radical absorption capacity (ARAC) assay method. The free radical absorption capacity (ARAC value) of each tocopherol was determined through measurement of the radical-scavenging rate constant in ethanol. The ARAC value could also be evaluated through measurement of the half-life of the aroxyl radical during the scavenging reaction. For the estimation of the free radical absorption capacity, the aroxyl radical was more suitable than the DPPH radical, galvinoxyl, and p-nitrophenyl nitronyl nitroxide. The ARAC value in tocopherols showed the same tendency as the free radical absorption capacities reported previously, and the tendency was independent of an oxygen radical participating in the scavenging reaction and of a medium surrounding the tocopherol and oxygen radical. The ARAC value can be directly connected to the free radical-scavenging rate constant, and the ARAC method has the advantage of treating a stable and isolable radical (aroxyl radical) in a user-friendly organic solvent (ethanol). The ARAC method was also successfully applied to a palm oil extract. Accordingly, the ARAC method would be useful in free radical absorption capacity assay of antioxidative reagents and foods.

  18. Free radical generation induced by ultrasound in red wine and model wine: An EPR spin-trapping study.

    Science.gov (United States)

    Zhang, Qing-An; Shen, Yuan; Fan, Xue-Hui; Martín, Juan Francisco García; Wang, Xi; Song, Yun

    2015-11-01

    Direct evidence for the formation of 1-hydroxylethyl radicals by ultrasound in red wine and air-saturated model wine is presented in this paper. Free radicals are thought to be the key intermediates in the ultrasound processing of wine, but their nature has not been established yet. Electron paramagnetic resonance (EPR) spin trapping with 5,5-dimethyl-l-pyrrolin N-oxide (DMPO) was used for the detection of hydroxyl free radicals and 1-hydroxylethyl free radicals. Spin adducts of hydroxyl free radicals were detected in DMPO aqueous solution after sonication while 1-hydroxylethyl free radical adducts were observed in ultrasound-processed red wine and model wine. The latter radical arose from ethanol oxidation via the hydroxyl radical generated by ultrasound in water, thus providing the first direct evidence of the formation of 1-hydroxylethyl free radical in red wine exposed to ultrasound. Finally, the effects of ultrasound frequency, ultrasound power, temperature and ultrasound exposure time were assessed on the intensity of 1-hydroxylethyl radical spin adducts in model wine. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Use of a cocktail of spin traps for fingerprinting large range of free radicals in biological systems.

    Science.gov (United States)

    Marchand, Valérie; Charlier, Nicolas; Verrax, Julien; Buc-Calderon, Pedro; Levêque, Philippe; Gallez, Bernard

    2017-01-01

    It is well established that the formation of radical species centered on various atoms is involved in the mechanism leading to the development of several diseases or to the appearance of deleterious effects of toxic molecules. The detection of free radical is possible using Electron Paramagnetic Resonance (EPR) spectroscopy and the spin trapping technique. The classical EPR spin-trapping technique can be considered as a "hypothesis-driven" approach because it requires an a priori assumption regarding the nature of the free radical in order to select the most appropriate spin-trap. We here describe a "data-driven" approach using EPR and a cocktail of spin-traps. The rationale for using this cocktail was that it would cover a wide range of biologically relevant free radicals and have a large range of hydrophilicity and lipophilicity in order to trap free radicals produced in different cellular compartments. As a proof-of-concept, we validated the ability of the system to measure a large variety of free radicals (O-, N-, C-, or S- centered) in well characterized conditions, and we illustrated the ability of the technique to unambiguously detect free radical production in cells exposed to chemicals known to be radical-mediated toxic agents.

  20. Free Radical Damage in Ischemia-Reperfusion Injury: An Obstacle in Acute Ischemic Stroke after Revascularization Therapy

    Directory of Open Access Journals (Sweden)

    Ming-Shuo Sun

    2018-01-01

    Full Text Available Acute ischemic stroke is a common cause of morbidity and mortality worldwide. Thrombolysis with recombinant tissue plasminogen activator and endovascular thrombectomy are the main revascularization therapies for acute ischemic stroke. However, ischemia-reperfusion injury after revascularization therapy can result in worsening outcomes. Among all possible pathological mechanisms of ischemia-reperfusion injury, free radical damage (mainly oxidative/nitrosative stress injury has been found to play a key role in the process. Free radicals lead to protein dysfunction, DNA damage, and lipid peroxidation, resulting in cell death. Additionally, free radical damage has a strong connection with inducing hemorrhagic transformation and cerebral edema, which are the major complications of revascularization therapy, and mainly influencing neurological outcomes due to the disruption of the blood-brain barrier. In order to get a better clinical prognosis, more and more studies focus on the pharmaceutical and nonpharmaceutical neuroprotective therapies against free radical damage. This review discusses the pathological mechanisms of free radicals in ischemia-reperfusion injury and adjunctive neuroprotective therapies combined with revascularization therapy against free radical damage.

  1. Micrococcus radiodurans surface exonuclease. Dimer to monomer conversion by ionizing radiation-generated aqueous free radicals

    Energy Technology Data Exchange (ETDEWEB)

    Mitchel, R E.J.

    1980-01-01

    Micrococcus radiodurans possesses an exonuclease firmly bound to a middle cell wall membrane layer. Aqueous OH/sup -/ radicals generated chemically or by ionizing radiation cause the immediate release of this enzyme into the surrounding medium. The enzyme is located in a hydrophobic site and can also be released by aqueous n-butanol. When extracted by this solvent it is a non-covalently linked dimer and has a molecular weight of 260,000 as determined by gel filtration. When released by radiation generated OH/sup -/ radicals, the enzyme initially appears in solution as the dimer but is rapidly split by further aqueous radical attack into two 130,000 molecular weight subunits. Hydroxyl radicals are most effective but reducing radicals are also able to monomerize the enzyme. Only the released dimer enzyme is subject to free radical monomerization. Bound dimer enzyme is not split prior to release. No detectable loss of activity or change in catalytic properties accompanies the free radical cleavage of the enzyme. Both subunits of the dimer enzyme possess a tightly bound metal ion (probably Ca/sup 2 +/) required for activity. The monomer but not the dimer enzyme will bind to an anion exchanger. The monomer is susceptible to loss of its metal ion, and consequent inactivation, when exposed to the exchanger in the absence of Ca/sup 2 +/. Besides providing information on some of the immediate non-lethal effects of ionizing radiation, the behavior of this enzyme system demonstrates a potential cellular mechanism by which internally or externally generated free radicals could be utilized by the cell to control various enzymic reactions.

  2. Daily grape juice consumption reduces oxidative DNA damage and plasma free radical levels in healthy Koreans

    International Nuclear Information System (INIS)

    Park, Yoo Kyoung; Park, Eunju; Kim, Jung-Shin; Kang, Myung-Hee

    2003-01-01

    Grape contains flavonoids with antioxidant properties which are believed to be protective against various types of cancer. This antioxidative protection is possibly provided by the effective scavenging of reactive oxygen species (ROS), thus defending cellular DNA from oxidative damage and potential mutations. This study of healthy adults tested whether a daily regimen of grape juice supplementation could reduce cellular DNA damage in peripheral lymphocytes and reduce the amount of free radicals released. Sixty-seven healthy volunteers (16 women and 51 men) aged 19-57 years were given 480 ml of grape juice daily for 8 weeks in addition to their normal diet, and blood samples were drawn before and after the intervention. The DNA damage was determined by using the single cell gel (comet) assay with alkaline electrophoresis and was quantified by measuring tail length (TL). Levels of free radicals were determined by reading the lucigenin-perborate ROS generating source, using the Ultra-Weak Chemiluminescence Analyzer System. Grape juice consumption resulted in a significant decrease in lymphocyte DNA damage expressed by TL (before supplementation: 88.75±1.55 μm versus after supplementation: 70.25±1.31 μm; P=0.000 by paired t-test). Additionally, grape juice consumption for 8 weeks reduced the ROS/photon count by 15%, compared to the beginning of the study. The preventive effect of grape juice against DNA damage was simultaneously shown in both sexes. These results indicate that the consumption of grape juice may increase plasma antioxidant capacity, resulting in reduced DNA damage in peripheral lymphocytes achieved at least partially by a reduced release of ROS. Our findings support the hypothesis that polyphenolic compounds contained in grape juice exert cancer-protective effects on lymphocytes, limiting oxidative DNA damage possibly via a decrease in free radical levels

  3. Daily grape juice consumption reduces oxidative DNA damage and plasma free radical levels in healthy Koreans

    Energy Technology Data Exchange (ETDEWEB)

    Park, Yoo Kyoung; Park, Eunju; Kim, Jung-Shin; Kang, Myung-Hee

    2003-08-28

    Grape contains flavonoids with antioxidant properties which are believed to be protective against various types of cancer. This antioxidative protection is possibly provided by the effective scavenging of reactive oxygen species (ROS), thus defending cellular DNA from oxidative damage and potential mutations. This study of healthy adults tested whether a daily regimen of grape juice supplementation could reduce cellular DNA damage in peripheral lymphocytes and reduce the amount of free radicals released. Sixty-seven healthy volunteers (16 women and 51 men) aged 19-57 years were given 480 ml of grape juice daily for 8 weeks in addition to their normal diet, and blood samples were drawn before and after the intervention. The DNA damage was determined by using the single cell gel (comet) assay with alkaline electrophoresis and was quantified by measuring tail length (TL). Levels of free radicals were determined by reading the lucigenin-perborate ROS generating source, using the Ultra-Weak Chemiluminescence Analyzer System. Grape juice consumption resulted in a significant decrease in lymphocyte DNA damage expressed by TL (before supplementation: 88.75{+-}1.55 {mu}m versus after supplementation: 70.25{+-}1.31 {mu}m; P=0.000 by paired t-test). Additionally, grape juice consumption for 8 weeks reduced the ROS/photon count by 15%, compared to the beginning of the study. The preventive effect of grape juice against DNA damage was simultaneously shown in both sexes. These results indicate that the consumption of grape juice may increase plasma antioxidant capacity, resulting in reduced DNA damage in peripheral lymphocytes achieved at least partially by a reduced release of ROS. Our findings support the hypothesis that polyphenolic compounds contained in grape juice exert cancer-protective effects on lymphocytes, limiting oxidative DNA damage possibly via a decrease in free radical levels.

  4. VEGF secretion during hypoxia depends on free radicals-induced Fyn kinase activity in mast cells

    International Nuclear Information System (INIS)

    Garcia-Roman, Jonathan; Ibarra-Sanchez, Alfredo; Lamas, Monica; Gonzalez Espinosa, Claudia

    2010-01-01

    Research highlights: → Bone marrow-derived mast cells (BMMCs) secrete functional VEGF but do not degranulate after Cobalt chloride-induced hypoxia. → CoCl 2 -induced VEGF secretion in mast cells occurs by a Ca 2+ -insensitive but brefeldin A and Tetanus toxin-sensitive mechanism. → Trolox and N-acetylcysteine inhibit hypoxia-induced VEGF secretion but only Trolox inhibits FcεRI-dependent anaphylactic degranulation in mast cells. → Src family kinase Fyn activation after free radical production is necessary for hypoxia-induced VEGF secretion in mast cells. -- Abstract: Mast cells (MC) have an important role in pathologic conditions such as asthma and chronic obstructive pulmonary disease (COPD), where hypoxia conduce to deleterious inflammatory response. MC contribute to hypoxia-induced angiogenesis producing factors such as vascular endothelial growth factor (VEGF), but the mechanisms behind the control of hypoxia-induced VEGF secretion in this cell type is poorly understood. We used the hypoxia-mimicking agent cobalt chloride (CoCl 2 ) to analyze VEGF secretion in murine bone marrow-derived mast cells (BMMCs). We found that CoCl 2 promotes a sustained production of functional VEGF, able to induce proliferation of endothelial cells in vitro. CoCl 2 -induced VEGF secretion was independent of calcium rise but dependent on tetanus toxin-sensitive vesicle-associated membrane proteins (VAMPs). VEGF exocytosis required free radicals formation and the activation of Src family kinases. Interestingly, an important deficiency on CoCl 2 -induced VEGF secretion was observed in Fyn kinase-deficient BMMCs. Moreover, Fyn kinase was activated by CoCl 2 in WT cells and this activation was prevented by treatment with antioxidants such as Trolox and N-acetylcysteine. Our results show that BMMCs are able to release VEGF under hypoxic conditions through a tetanus toxin-sensitive mechanism, promoted by free radicals-dependent Fyn kinase activation.

  5. VEGF secretion during hypoxia depends on free radicals-induced Fyn kinase activity in mast cells

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Roman, Jonathan; Ibarra-Sanchez, Alfredo; Lamas, Monica [Departamento de Farmacobiologia, Centro de Investigacion y de Estudios Avanzados del IPN (Cinvestav, IPN) (Mexico); Gonzalez Espinosa, Claudia, E-mail: cgonzal@cinvestav.mx [Departamento de Farmacobiologia, Centro de Investigacion y de Estudios Avanzados del IPN (Cinvestav, IPN) (Mexico)

    2010-10-15

    Research highlights: {yields} Bone marrow-derived mast cells (BMMCs) secrete functional VEGF but do not degranulate after Cobalt chloride-induced hypoxia. {yields} CoCl{sub 2}-induced VEGF secretion in mast cells occurs by a Ca{sup 2+}-insensitive but brefeldin A and Tetanus toxin-sensitive mechanism. {yields} Trolox and N-acetylcysteine inhibit hypoxia-induced VEGF secretion but only Trolox inhibits Fc{epsilon}RI-dependent anaphylactic degranulation in mast cells. {yields} Src family kinase Fyn activation after free radical production is necessary for hypoxia-induced VEGF secretion in mast cells. -- Abstract: Mast cells (MC) have an important role in pathologic conditions such as asthma and chronic obstructive pulmonary disease (COPD), where hypoxia conduce to deleterious inflammatory response. MC contribute to hypoxia-induced angiogenesis producing factors such as vascular endothelial growth factor (VEGF), but the mechanisms behind the control of hypoxia-induced VEGF secretion in this cell type is poorly understood. We used the hypoxia-mimicking agent cobalt chloride (CoCl{sub 2}) to analyze VEGF secretion in murine bone marrow-derived mast cells (BMMCs). We found that CoCl{sub 2} promotes a sustained production of functional VEGF, able to induce proliferation of endothelial cells in vitro. CoCl{sub 2}-induced VEGF secretion was independent of calcium rise but dependent on tetanus toxin-sensitive vesicle-associated membrane proteins (VAMPs). VEGF exocytosis required free radicals formation and the activation of Src family kinases. Interestingly, an important deficiency on CoCl{sub 2}-induced VEGF secretion was observed in Fyn kinase-deficient BMMCs. Moreover, Fyn kinase was activated by CoCl{sub 2} in WT cells and this activation was prevented by treatment with antioxidants such as Trolox and N-acetylcysteine. Our results show that BMMCs are able to release VEGF under hypoxic conditions through a tetanus toxin-sensitive mechanism, promoted by free radicals

  6. Effects of EGTA and antioxidants on the interaction of phenothiazine free radicals with calmodulin

    International Nuclear Information System (INIS)

    Prozialeck, W.C.

    1986-01-01

    Upon irradiation with UV light or treatment with horseradish peroxidase (HRP), phenothiazines generate free radicals that bind irreversibly to calmodulin (CaM). The purpose of the present studies was to examine the effects of the Ca 2+ -chelator EGTA and various antioxidants on the binding of these phenothiazine radicals to CaM. Solutions containing 2 μM CaM, 10 μM 3 H-chlorpromazine, 10 μM CaCl 2 , and either EGTA or the antioxidants (2mM), were irradiated with UV light or treated with HRP-H 2 O 2 . Samples were dialyzed to remove free chlorpromazine and counted for radioactivity. The antioxidants (ascorbic acid, dithiothreitol and glutathione) inhibited the HRP-induced irreversible binding by 95-100% but had little effect on the UV-induced binding. EGTA inhibited the HRP-induced binding by 100% but reduced the UV-induced binding by only 70%. The inhibition of the UV-induced binding by EGTA could be prevented by incubating the samples in the presence of excess Ca 2+ . By contrast, Ca 2+ did not prevent the inhibition of the HRP-induced binding by EGTA. These findings indicate that EGTA and antioxidants inhibit the HRP-induced irreversible binding of chlorpromazine to CaM by interacting with the chlorpromazine free radical and not by modifying CaM or chelating Ca 2+ . The fact that the UV-induced binding is resistant to inhibition by the antioxidants suggests that chlorpromazine binds to the Ca 2+ -CaM complex before photoactivation causes the formation of the free radical

  7. Electronic Paramagnetic Resonance (EPR) of free radicals induced by X-rays in pyrene

    International Nuclear Information System (INIS)

    Moya Partiti, C.S. de.

    1982-01-01

    Pyrene single crystals C 16 H 10 , irradiated by X-rays, at room temperature, were studied by EPR technique, to determine free radicals formed by radiation. The angular dependence of EPR spectra was explained by the presence of two kinds of radicals with an aditional hydrogen: 2-H 2 pyrene and 3-H 2 pyrene. It was studied the isothermic decay of the EPR signal and two typical values for the activation energy were found = (1,9+-0,1) eV and (1,93+-0,03) eV. (author) [pt

  8. Correction of Free Radical Lipid Oxidation in Internal Female Genital Inflammatory Diseases

    Directory of Open Access Journals (Sweden)

    A. D. Belyaevsky

    2008-01-01

    Full Text Available The paper descries a specific view on the mechanism responsible for development of the resistance of an inflammatory process in the female genital tract to drugs and on the role of a free radical process activation factor in the pathogenesis of the disease. Emphasis is laid on the importance of measures to diminish cell membrane permeability, by correcting their structural and functional states with antioxidants. Key words: inflammatory processes in the female genital organs, lipid peroxidation, antioxidative defense, cell membrane structural and functional state.

  9. Radiation-induced polymerisation of 2,3-dihydrofuran: free-radical or cationic mechanism?

    International Nuclear Information System (INIS)

    Janovsky, Igor; Naumov, Sergej; Knolle, Wolfgang; Mehnert, Reiner

    2005-01-01

    Concentrated (10 mol%) solutions of 2,3-dihydrofuran in CFCl 2 CF 2 Cl matrix were irradiated at 77 K and several intermediates (dimer radical cation, dihydrofuryl radical, and polymer radicals) were observed by low-temperature EPR spectroscopy. The irradiated solutions yielded after melting a polymeric product, which was characterised by IR spectroscopy and gel permeation chromatography. The polydisperse polymer is assumed to be formed mainly by a cationic process initiated by a dimer carbocation. The free-radical mechanism via the dihydrofuryl radical leads to low molecular weight oligomers only. Quantum chemical calculations support the interpretation of the experimental results

  10. μSR spectroscopy on free radicals: a complement to ESR spectroscopy

    International Nuclear Information System (INIS)

    Cox, S.F.J.; Symons, M.C.R.

    1986-12-01

    The paper on ''μSR spectroscopy on free radicals'' was presented to the conference on ''Muon spin, rotation, relaxation and resonance'' Uppsala, 1986. The spectroscopic techniques for both ESR and μSR are described, along with the interpretation of the spectra, hyperfine coupling constants and radical structure. A comparison of ESR and μSR data is carried out with respect: to 1) isotope effects in organic radicals, 2) isotope effects in solids, -the isotropic muonium defect centres, and 3) the muonium defect centres in semiconductors. Radical categories examined using ESR and μSR are discussed, including new species, formation mechanisms, and ionic species. (U.K.)

  11. Free radicals of an aromatic nature in air samples from iron foundries

    Energy Technology Data Exchange (ETDEWEB)

    Westerberg, L M

    1982-01-01

    Free radicals of relatively long life were identified as spin adducts of phenyl-N-tert-butylnitrone. Pyrolysis studies showed the radicals were oxy-radicals. The hyperfine splitting constants of spin adducts of radicals from the pyrolysis in air of benzo(a)pyrene, coal tar pitch, and moulding sand containing hard coal dust were the same as those of the radicals found in foundry air. Since these radicals can bind to DNA, they must be considered when estimating the hazardous effects of polluted air.

  12. Moessbauer effect study of iron(III)-inidazolidine nitroxyl-free radical ligand complex

    Energy Technology Data Exchange (ETDEWEB)

    Mulaba, A. [Technikon Witwatersrand, Metallurgy Department (South Africa); Kiremire, E. [University of the Witwatersrand, Chemistry Department (South Africa); Pollak, H. [University of the Witwatersrand, Physics Department (South Africa); Boeyens, J. [University of the Witwatersrand, Chemistry Department (South Africa)

    1999-09-15

    A new complex, [Fe(acac)L{sub 2}], bearing inidazolidine nitroxyl-free radical ligand (L{sup -}) was recently synthesised for biological studies. It proved to be biologically active against African sleeping sickness, plasmodium falciparum (malaria), leishmaniasis and chaga disease causative agents. Three ESR well resolved peaks indicated the presence of a free (unpaired) and chemically active electron in the complex. The structural complex ferric iron was found at the centre of two electric gradient whose the biggest is suggested to be initiated by the unpaired charge. No distinction between different cis isomers could be made.

  13. Free radicals and low-level photon emission in human pathogenesis: state of the art.

    Science.gov (United States)

    Van Wijk, Roeland; Van Wijk, Eduard P A; Wiegant, Fred A C; Ives, John

    2008-05-01

    Convincing evidence supports a role for oxidative stress in the pathogenesis of many chronic diseases. The model includes the formation of radical oxygen species (ROS) and the misassembly and aggregation of proteins when three tiers of cellular defence are insufficient: (a) direct antioxidative systems, (b) molecular damage repairing systems, and (c) compensatory chaperone synthesis. The aim of the present overview is to introduce (a) the basics of free radical and antioxidant metabolism, (b) the role of the protein quality control system in protecting cells from free radical damage and its relation to chronic diseases, (c) the basics of the ultraweak luminescence as marker of the oxidant status of biological systems, and (d) the research in human photon emission as a non-invasive marker of oxidant status in relation to chronic diseases. In considering the role of free radicals in disease, both their generation and their control by the antioxidant system are part of the story. Excessive free radical production leads to the production of heat shock proteins and chaperone proteins as a second line of protection against damage. Chaperones at the molecular level facilitate stress regulation vis-à-vis protein quali y control mechanisms. The manifestation of misfolded proteins and aggregates is a hallmark of a range of neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, amylotrophic lateral sclerosis, polyglutamine (polyQ) diseases, diabetes and many others. Each of these disorders exhibits aging-dependent onset and a progressive, usually fatal clinical course. The second part reviews the current status of human photon emission techniques and protocols for recording the human oxidative status. Sensitive photomultiplier tubes may provide a tool for non-invasive and continuous monitoring of oxidative metabolism. In that respect, recording ultraweak luminescence has been favored compared to other indirect assays. Several biological models have

  14. Moessbauer effect study of iron(III)-inidazolidine nitroxyl-free radical ligand complex

    International Nuclear Information System (INIS)

    Mulaba, A.; Kiremire, E.; Pollak, H.; Boeyens, J.

    1999-01-01

    A new complex, [Fe(acac)L 2 ], bearing inidazolidine nitroxyl-free radical ligand (L - ) was recently synthesised for biological studies. It proved to be biologically active against African sleeping sickness, plasmodium falciparum (malaria), leishmaniasis and chaga disease causative agents. Three ESR well resolved peaks indicated the presence of a free (unpaired) and chemically active electron in the complex. The structural complex ferric iron was found at the centre of two electric gradient whose the biggest is suggested to be initiated by the unpaired charge. No distinction between different cis isomers could be made

  15. Thermal, tensile and rheological properties of high density polyethylene (HDPE) processed and irradiated by gamma-ray in different atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Ferreto, H. F. R., E-mail: hferreto@ipen.br, E-mail: ana-feitoza@yahoo.com.br; Oliveira, A. C. F., E-mail: hferreto@ipen.br, E-mail: ana-feitoza@yahoo.com.br; Parra, D. F., E-mail: dfparra@ipen.br, E-mail: ablugao@ipen.br; Lugão, A. B., E-mail: dfparra@ipen.br, E-mail: ablugao@ipen.br [Center of Chemistry and Environment, Institute of Energy and Nuclear Research - IPEN (Brazil); Gaia, R., E-mail: renan-gaia7@hotmail.com [Faculdades Oswaldo Cruz (Brazil)

    2014-05-15

    The aim of this paper is to investigate structural changes of high density polyethylene (HDPE) modified by ionizing radiation (gamma rays) in different atmospheres. The gamma radiation process for modification of commercial polymers is a widely applied technique to promote new physical-chemical and mechanical properties. Gamma irradiation originates free radicals which can induce chain scission or recombination, providing its annihilation, branching or crosslinking. This polymer was irradiated with gamma source of {sup 60}Co at doses of 5, 10, 20, 50 or 100 kGy at a dose rate of 5 kGy/h. The changes in molecular structure of HDPE, after gamma irradiations were evaluated using thermogravimetric analysis (TGA) and tensile machine and oscillatory rheology. The results showed the variations of the properties depending on the dose at each atmosphere.

  16. Importing low-density ideas to high-density revitalisation

    DEFF Research Database (Denmark)

    Arnholtz, Jens; Ibsen, Christian Lyhne; Ibsen, Flemming

    2016-01-01

    Why did union officials from a high-union-density country like Denmark choose to import an organising strategy from low-density countries such as the US and the UK? Drawing on in-depth interviews with key union officials and internal documents, the authors of this article argue two key points. Fi...

  17. Evaluation of antioxidant, free radical scavenging and antimicrobial, activity of Quercus incana Roxb.

    Directory of Open Access Journals (Sweden)

    Rizwana eSarwar

    2015-11-01

    Full Text Available Considering the indigenous utilization of Quercus incana Roxb., the present study deals with the investigation of antioxidant, free radical scavenging activity, total phenolic content and antimicrobial activity of Quercus incana Roxb. In vitro antioxidant activity of the plant fractions were determined by DPPH and NO scavenging method. Total phenolic contents were determined by gallic acid equivalent (GAE and antimicrobial activities were determined by agar well diffusion method. It was observed that Quercus incana Roxb. showed significant antibacterial activity against Gram-positive and Gram-negative bacteria. n-Butanol fraction showed maximum activity against Micrococcus leuteus with 19 mm zone of inhibition. n-Butanol fraction of Quercus incana Roxb. showed immense antifungal activity against Aspergillus niger (32 mm ± 0.55 and Aspergillus flavus (28 mm ± 0.45. Similarly n-butanol fraction showed relatively good antioxidant activity with IC50 value of 55.4 ± 0.21μg/mL. The NO scavenging activity of ethyl acetate fraction (IC50 = 23.21 ± 0.31 μg/mL was fairly good compared to other fractions. The current study of Quercus incana Roxb. suggests the presences of synergetic action of some biological active compounds that may be present in the leaves of medicinal plant. Further studies are needed to better characterize the important active constituents responsible for the antimicrobial, antioxidant and free radical scavenging activity.

  18. ESR detection of free radicals in gamma irradiated spices and other foodstuffs

    Energy Technology Data Exchange (ETDEWEB)

    Pilbrow, J.R.; Troup, G.J.; Hutton, D.R. [Monash Univ., Clayton, VIC (Australia). Dept. of Physics; Hunter, C.R. [Monash Univ., Clayton, VIC (Australia). Dept. of Astronomy

    1996-12-31

    Irradiation of various food products, including vegetables, fruits, meats, seafoods, herbs, spices and seeds by appropriate doses of {gamma}-rays has for many years been suggested as a means of killing or sterilizing bacteria, viruses and pests and, therefore, as a means of preserving the foods. The position of food irradiation has been under review in Australia generally, through consumer organisations and by a Federal Government (House of Representatives) inquiry. From these reviews and inquiries, recommendations for irradiation, packaging, and labelling etc., are emerging with, for example, an NH and MRC recommended maximum dose of 10 kGy for Australia, with 6 kGy being a minimum dose for grains and spices. In early studies, electron spin resonance (ESR) spectroscopy was used to detect stable free radicals in bone and cuticle and it was demonstrated that {gamma}-irradiation breaks down proteins and DNA. Earlier studies suggested that induced free radical signals in spices rapidly decayed to negligible levels after three weeks, especially if some moisture was present. Although the members of the Monash group do not carry out research formally in the area of food technology, participation in the ADMIT program was appropriate given the availability of suitable ESR and {sup 137}Cs irradiation facilities and interest both politically and amongst consumer groups regarding food irradiation. (author).

  19. Development of sensors for monitoring oxygen and free radicals in plant physiology

    Science.gov (United States)

    Chaturvedi, Prachee

    Oxygen plays a critical role in the physiology of photosynthetic organisms, including bioenergetics, metabolism, development, and stress response. Oxygen levels affect photosynthesis, respiration, and alternative oxidase pathways. Likewise, the metabolic rate of spatially distinct plant cells (and therefore oxygen flux) is known to be affected by biotic stress (e.g., herbivory) and environmental stress (e.g., salt/nutrient stress). During aerobic metabolism, cells produce reactive oxygen species (ROS) as a by product. Plants also produce ROS during adaptation to stress (e.g., abscisic acid (ABA) mediated stress responses). If stress conditions are prolonged, ROS levels surpass the capacity of detoxifying mechanisms within the cell, resulting in oxidative damage. While stress response pathways such as ABA-mediated mechanisms have been well characterized (e.g., water stress, inhibited shoot growth, synthesis of storage proteins in seeds), the connection between ROS production, oxygen metabolism and stress response remains unknown. In part, this is because details of oxygen transport at the interface of cell(s) and the surrounding microenvironment remains nebulous. The overall goal of this research was to develop oxygen and Free radical sensors for studying stress signaling in plants. Recent developments in nanomaterials and data acquisition systems were integrated to develop real-time, non-invasive oxygen and Free radical sensors. The availability of these sensors for plant physiologists is an exciting opportunity to probe the functional realm of cells and tissues in ways that were not previously possible.

  20. Extraction and free radical scavenging activity of polysaccharide from 'Anji Baicha' (Camellia sinensis (L.) O. Kuntze).

    Science.gov (United States)

    Zhang, Zhongshan; Wang, Xiaomei; Li, Jingfen; Wang, Guozhi; Mao, Genxiang

    2016-03-01

    In this study, the optimization of the extraction conditions of polysaccharide from 'Anji Baicha' (Camellia sinensis (L.) O. Kuntze) (AP) was investigated by response surface methodology (RSM). Three main independent variables (extraction temperature, time, ratio of water to raw material) were taken into consideration. And then the free radical scavenging activities of the sample were investigated including scavenging effects of superoxide and hydroxyl radicals. The RSM analysis showed good correspondence between experimental and predicted values.. The optimal condition to obtain the highest yield of AP was determined as follows: temperature 76.79 °C, time 2.48 h, ratio of water to material 22.53 mL/g. For the free radical scavenging activity, the IC50 values of Vc and AP were 7.78 and 83.25 μg/mL. And for the scavenging effect on hydroxyl radical, that of AP and Vc were 1.80 and 1.69 mg/mL. AP showed excellent antioxidant activity. This exhibited AP had a good potential for antioxidant. The purification and structure needs to be study in further. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Free-Radical-Scavenging, Antityrosinase, and Cellular Melanogenesis Inhibitory Activities of Synthetic Isoflavones.

    Science.gov (United States)

    Lu, Tzy-Ming; Ko, Horng-Huey; Ng, Lean-Teik; Hsieh, Yen-Pin

    2015-06-01

    In this study, we examined the potential of synthetic isoflavones for application in cosmeceuticals. Twenty-five isoflavones were synthesized and their capacities of free-radical-scavenging and mushroom tyrosinase inhibition, as well as their impact on cell viability of B16F10 murine melanoma cells and HaCaT human keratinocytes were evaluated. Isoflavones that showed significant mushroom tyrosinase inhibitory activities were further studied on reduction of cellular melanin formation and antityrosinase activities in B16F10 melanocytes in vitro. Among the isoflavones tested, 6-hydroxydaidzein (2) was the strongest scavenger of both ABTS(.+) and DPPH(.) radicals with SC50 values of 11.3 ± 0.3 and 9.4 ± 0.1 μM, respectively. Texasin (20) exhibited the most potent inhibition of mushroom tyrosinase (IC50 14.9 ± 4.5 μM), whereas retusin (17) showed the most efficient inhibition both of cellular melanin formation and antityrosinase activity in B16F10 melanocytes, respectively. In summary, both retusin (17) and texasin (20) exhibited potent free-radical-scavenging capacities as well as efficient inhibition of cellular melanogenesis, suggesting that they are valuable hit compounds with potential for advanced cosmeceutical development. Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich.

  2. Ceruloplasmin (ferroxidase) oxidizes hydroxylamine probes: deceptive implications for free radical detection.

    Science.gov (United States)

    Ganini, Douglas; Canistro, Donatella; Jiang, JinJie; Jang, JinJie; Stadler, Krisztian; Mason, Ronald P; Kadiiska, Maria B

    2012-10-01

    Ceruloplasmin (ferroxidase) is a copper-binding protein known to promote Fe(2+) oxidation in plasma of mammals. In addition to its classical ferroxidase activity, ceruloplasmin is known to catalyze the oxidation of various substrates, such as amines and catechols. Assays based on cyclic hydroxylamine oxidation are used to quantify and detect free radicals in biological samples ex vivo and in vitro. We show here that human ceruloplasmin promotes the oxidation of the cyclic hydroxylamine 1-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine hydrochloride (CPH) and related probes in Chelex-treated phosphate buffer and rat serum. The reaction is suppressed by the metal chelators DTPA, EDTA, and desferal, whereas heparin and bathocuproine have no effect. Catalase or superoxide dismutase additions do not interfere with the CPH-oxidation yield, demonstrating that oxygen-derived free radicals are not involved in the CPH oxidation mediated by ceruloplasmin. Plasma samples immunodepleted of ceruloplasmin have lower levels of CPH oxidation, which confirms the role of ceruloplasmin (ferroxidase) as a biological oxidizing agent of cyclic hydroxylamines. In conclusion, we show that the ferroxidase activity of ceruloplasmin is a possible biological source of artifacts in the cyclic hydroxylamine-oxidation assay used for reactive oxygen species detection and quantification. Published by Elsevier Inc.

  3. Addressing Emerging Risks: Scientific and Regulatory Challenges Associated with Environmentally Persistent Free Radicals

    Directory of Open Access Journals (Sweden)

    Tammy R. Dugas

    2016-06-01

    Full Text Available Airborne fine and ultrafine particulate matter (PM are often generated through widely-used thermal processes such as the combustion of fuels or the thermal decomposition of waste. Residents near Superfund sites are exposed to PM through the inhalation of windblown dust, ingestion of soil and sediments, and inhalation of emissions from the on-site thermal treatment of contaminated soils. Epidemiological evidence supports a link between exposure to airborne PM and an increased risk of cardiovascular and pulmonary diseases. It is well-known that during combustion processes, incomplete combustion can lead to the production of organic pollutants that can adsorb to the surface of PM. Recent studies have demonstrated that their interaction with metal centers can lead to the generation of a surface stabilized metal-radical complex capable of redox cycling to produce ROS. Moreover, these free radicals can persist in the environment, hence their designation as Environmentally Persistent Free Radicals (EPFR. EPFR has been demonstrated in both ambient air PM2.5 (diameter < 2.5 µm and in PM from a variety of combustion sources. Thus, low-temperature, thermal treatment of soils can potentially increase the concentration of EPFR in areas in and around Superfund sites. In this review, we will outline the evidence to date supporting EPFR formation and its environmental significance. Furthermore, we will address the lack of methodologies for specifically addressing its risk assessment and challenges associated with regulating this new, emerging contaminant.

  4. Free radical formation in DNA: Some new aspects of an old problem

    International Nuclear Information System (INIS)

    Huettermann, J.; Gatzweiler, W.; Lange, M.; Weiland, B.

    1995-01-01

    Despite extensive efforts over the past three decades or more, there is a continuing debate about the number of different free radicals and their detailed chemical structure obtained from DNA irradiated under various conditions concerning, among others, hydration state, temperature of irradiation or measurement, base composition, and radiation dose or quality. The only proposal accepted unanimously is the 5-yl radical on the base thymine involving net H-gain at carbon C 6 denoted T(C 6 + H). Its octet spectrum which usually appears, after irradiation at e.g. 77 K, at elevated temperatures (ca. 200 K) provides for an unmistakable fingerprint in Electron Spin Resonance (ESR) spectroscopy, the method of choice for investigating free radicals in general. All other proposals of radical structures, nothing to say about details of their mechanism of formation or their subsequent reactions, have been challenged and are under debate. This apparently disturbing situation can, in the authors view, be traced back to several fundamental reasons which result from inherent limitations of both the sample itself and of the method of investigation

  5. A free radical scavenger edaravone suppresses systemic inflammatory responses in a rat transient focal ischemia model.

    Science.gov (United States)

    Fujiwara, Norio; Som, Angel T; Pham, Loc-Duyen D; Lee, Brian J; Mandeville, Emiri T; Lo, Eng H; Arai, Ken

    2016-10-28

    A free radical scavenger edaravone is clinically used in Japan for acute stroke, and several basic researches have carefully examined the mechanisms of edaravone's protective effects. However, its actions on pro-inflammatory responses under stroke are still understudied. In this study, we subjected adult male Sprague-Dawley rats to 90-min middle cerebral artery (MCA) occlusion followed by reperfusion. Edaravone was treated twice via tail vein; after MCA occlusion and after reperfusion. As expected, edaravone-treated group showed less infarct volume and edema formation compared with control group at 24-h after an ischemic onset. Furthermore, edaravone reduced the levels of plasma interleukin (IL)-1β and matrix metalloproteinase-9 at 3-h after ischemic onset. Several molecules besides IL-1β and MMP-9 are involved in inflammatory responses under stroke conditions. Therefore, we also examined whether edaravone treatment could decrease a wide range of pro-inflammatory cytokines/chemokines by testing rat plasma samples with a rat cytokine array. MCAO rats showed elevations in plasma levels of CINC-1, Fractalkine, IL-1α, IL-1ra, IL-6, IL-10, IP-10, MIG, MIP-1α, and MIP-3α, and all these increases were reduced by edaravone treatment. These data suggest that free radical scavengers may reduce systemic inflammatory responses under acute stroke conditions, and therefore, oxidative stress can be still a viable target for acute stroke therapy. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  6. Edaravone, a potent free radical scavenger, reacts with peroxynitrite to produce predominantly 4-NO-edaravone.

    Science.gov (United States)

    Fujisawa, Akio; Yamamoto, Yorihiro

    2016-05-01

    3-Methyl-1-phenyl-2-pyrazolin-5-one (edaravone) is used in clinical treatment of acute brain infarction to rescue the penumbra, based on its ability to prevent lipid peroxidation by scavenging lipid peroxyl radicals. Here, we show that edaravone also reacts with peroxynitrite to yield 4-NO-edaravone as the major product and 4-NO2-edaravone as a minor product. We observed little formation of 3-methyl-1-phenyl-2-pyrazolin-4,5-dione (4-oxoedaravone) and its hydrate, 2-oxo-3-(phenylhydrazono)butanoic acid, which are the major free radical-induced oxidation products of edaravone, suggesting that free radicals are not involved in the reaction with peroxynitrite. The reaction of peroxynitrite with edaravone is approximately 30-fold greater than with uric acid, a physiological peroxynitrite scavenger (reaction rate k = 1.5 × 10 (4)  M(-1) s(-1) vs. 480 M(-1) s(-1)). These results suggest that edaravone functions therapeutically as a scavenger of peroxynitrite as well as lipid peroxyl radicals, which is consistent with a report that edaravone treatment reduced levels of 3-nitrotyrosine in the cerebrospinal fluid of patients with amyotrophic lateral sclerosis.

  7. Protection from radiation-induced enteropathy by elemental diet feeding: The role of free radicals

    International Nuclear Information System (INIS)

    McArdle, A.H.; Duong, M.N.

    1991-01-01

    Free radicals have been implicated in intestinal reperfusion injury following ischemia and in epithelial cell damage resulting from ionizing radiation. Elemental diets (ED) have been shown to afford significant prophylaxis to the intestine from these injuries. The purpose of the present study was to investigate whether ED alters the activity of the defense mechanisms necessary for free radical removal. Six female dogs, fed on normal dog chow, had a 30 cm resection of terminal ileum to form Thiry-Vella loops. The main intestine was biopsied and anastomosed. Two weeks later, biopsies were taken from the lips of the loops. Following this, the loops were fed daily with ED another 2 weeks and biopsied again. The dogs were then placed on ED for 3 days before and during 4 days of pelvic irradiation, and the loops also were fed ED daily; after which the animals were again anesthetized, and the loops and main intestine were biopsied. All biopsies were processed for histology, and assayed for xanthine oxidase (XO), superoxide dismutase (SOD), glutathione peroxidase (GSP) and catalase (CAT). The XO and SOD pathway of free oxygen radical generation and scavenging are not affected by radiation. However, ED lowers both XO and SOD activity and may result in a reduced production of peroxides. The significantly increased activity of GSP and CAT when ED is fed improves the scavenging capacity of the free hydroxyl radicals generated by the radiation, and is an important adjunct to an understanding of ED prophylaxis

  8. ESR detection of free radicals in gamma irradiated spices and other foodstuffs

    International Nuclear Information System (INIS)

    Pilbrow, J.R.; Troup, G.J.; Hutton, D.R.; Hunter, C.R.

    1996-01-01

    Irradiation of various food products, including vegetables, fruits, meats, seafoods, herbs, spices and seeds by appropriate doses of γ-rays has for many years been suggested as a means of killing or sterilizing bacteria, viruses and pests and, therefore, as a means of preserving the foods. The position of food irradiation has been under review in Australia generally, through consumer organisations and by a Federal Government (House of Representatives) inquiry. From these reviews and inquiries, recommendations for irradiation, packaging, and labelling etc., are emerging with, for example, an NH and MRC recommended maximum dose of 10 kGy for Australia, with 6 kGy being a minimum dose for grains and spices. In early studies, electron spin resonance (ESR) spectroscopy was used to detect stable free radicals in bone and cuticle and it was demonstrated that γ-irradiation breaks down proteins and DNA. Earlier studies suggested that induced free radical signals in spices rapidly decayed to negligible levels after three weeks, especially if some moisture was present. Although the members of the Monash group do not carry out research formally in the area of food technology, participation in the ADMIT program was appropriate given the availability of suitable ESR and 137 Cs irradiation facilities and interest both politically and amongst consumer groups regarding food irradiation. (author)

  9. Free radical scavenging activity and secondary metabolites from in vitro cultures of Sanicula graveolens.

    Science.gov (United States)

    Cheel, José; Schmeda-Hirschmann, Guillermo; Jordan, Miguel; Theoduloz, Cristina; Rodríguez, Jaime A; Gerth, André; Wilken, Dirk

    2007-01-01

    An in vitro propagation system was developed to obtain shoot and root cultures from the Andean spice Sanicula graveolens (Apiaceae). Propagation of shoots, roots and plantlets was achieved by the temporary immersion system. The free radical scavenging effect of the methanol/water (7:3 v/v) extracts was determined by the discoloration of the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH). Total phenolic, flavonoid, chlorogenic acid (CA) and quercetin 3-O-glucoside content in the samples was assessed by spectrophotometry and DAD-HPLC analysis, respectively. On a dry weight basis, the crude extracts showed total phenolic values ranging from 3.57 to 6.93%, with highest content for the root culture sample. Total flavonoid content ranged from 1.23 to 2.23% and was lower for the root culture. Chlorogenic acid and neochlorogenic acid were identified by TLC in all samples. Highest free radical scavenging effect was observed for the root culture which also presented the highest CA content. Two of the shoot culture samples, with similar IC50 values in the DPPH discoloration assay, also presented close quercetin-3-O-glucoside content.

  10. ESR detection of free radicals in polyphenolic extracts from wine grapes, olives and green tea

    International Nuclear Information System (INIS)

    Troup, G.J.; Hutton, D.R.; Romani, A.; Mulinacci, N.; Vincieri, F.F.; Hunter, C.R.; Hewitt, D.G.

    1998-01-01

    Full text: Polyphenols are widespread in vegetables and fruits and they play an important role in human diet and health: these compounds act mainly as antioxidants and radical scavengers. In this work we have detected free radicals in the following natural polyphenols: Endotelon, an anthocyanic grapeskin extract; malvidin 3,5-O-diglucosides (malvin); oleuropein, an olive polyphenol; a commercial green tea extract, and pure epigallocatechingallate EGCG. The investigation was performed using a Varian E-12 ESR Spectrometer (∼9.1 GHz) at room temperature. All except the green tea extract gave single unstructured lines of ∼ 10 gauss linewidth. The tea extract signal showed 3 lines, one ∼ 20 gauss wide, one ∼ 10 gauss wide, and one ∼ 2-3 gauss wide. Saturation behaviour of these lines at room and liquid N 2 temperature showed them to be from different radicals About 50% of the extract is represented by epigallocatechingallate (EGCG). Using the pure sample EGCG it was possible to assign the appropriate radical, which corresponded with the broadest and strongest 'single' signal (∼20g wide). The presence of the free radicals in the solid extracts shows that the appropriate molecules can act as radical scavengers by forming stable radicals

  11. Preservation of kombucha tea-effect of temperature on tea components and free radical scavenging properties.

    Science.gov (United States)

    Jayabalan, Rasu; Marimuthu, Subbaiya; Thangaraj, Periyasamy; Sathishkumar, Muthuswamy; Binupriya, Arthur Raj; Swaminathan, Krishnaswami; Yun, Sei Eok

    2008-10-08

    Kombucha tea is sugared black tea fermented with a consortium of acetic acid bacteria and yeasts (tea fungus) for 14 days. The tea tastes slightly sweet and acidic. The formation of tea fungal biofilms during storage is a big problem when kombucha tea is being stored and commercialized. Various thermal treatments have been tried for long-term storage of kombucha tea. The present study revealed the influence of heat on the biochemical constituents and the free radical scavenging properties of kombucha tea. Heat treatment at 60, 65, and 68 degrees C for 1 min controlled biofilm formation in kombucha tea without changing its clarity, taste, and flavor. However, tea polyphenols and black tea quality parameters showed varying stability during the storage period. A decrease in free radical scavenging properties was also found during the storage period. Because the biological activities of kombucha tea depended on the biochemical constituents, it was concluded that heat treatment was not a suitable method for kombucha tea preservation.

  12. Role of enzymatic free radical scavengers in management of oxidative stress in autoimmune disorders.

    Science.gov (United States)

    Srivastava, Shikha; Singh, Deependra; Patel, Satish; Singh, Manju R

    2017-08-01

    Autoimmune disorders are distinct with over production and accumulation of free radicals due to its undisclosed genesis. The cause of numerous disorders as cancer, arthritis, psoriasis, diabetes, alzheimer's, cardiovascular disease, Parkinson's, respiratory distress syndrome, colitis, crohn's, pulmonary fibrosis, obesity and ageing have been associated with immune dysfunction and oxidative stress. In an oxidative stress, reactive oxygen species generally provoke the series of oxidation at cellular level. The buildup of free radicals in turn triggers various inflammatory cells causing release of various inflammatory interleukins, cytokines, chemokines, and tumor necrosis factors which mediate signal transduction and transcription pathways as nuclear factor- kappa B (NF-κB), signal transducer and activator of transcription 3 (STAT3), hypoxia-inducible factor-1 (HIF-1α) and nuclear factor-erythroid 2-related factor (Nrf2). The imbalance could only be combat by supplementing natural defensive antioxidant enzymes such as superoxide dismutase and catalase. The efficiency of these enzymes is enhanced by use of colloidal carriers which include cellular carriers, vesicular and particulate systems like erythrocytes, leukocytes, platelets, liposomes, transferosomes, solid lipid nanoparticles, microspheres, emulsions. Thus this review provides a platform for understanding importance of antioxidant enzymes and its therapeutic applications in treatment of various autoimmune disorders. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Inactivation of catalase by free radicals derived from oxygen via gamma radiolysis

    International Nuclear Information System (INIS)

    Malhaire, J.P.; Gardes-Albert, M.; Ferradini, C.; Sabourault, D.; Ribiere, C.

    1991-01-01

    The inactivation of catalase (10 -5 mol/l) by OH· or OH·/O 2 - · free radicals, at pH 7.4, has been investigated using γ radiolysis with doses up to 9000 Gy. Maxima initial G-values of catalase inactivation have been determined. These values are inferior to those of the free radicals OH· and O 2 - · produced by water radiolysis. Nevertheless, the presence of O 2 /O 2 - · enhances the inactivation due to OH· radicals. The general shape of the inactivation curves as a function of the radiation dose is biphasic: an initial rapid phase (from 0 to ∼ 500 Gy) followed by a slow phase (from ∼ 500 to 9000 Gy). The addition of H 2 O 2 at the beginning of irradiation decreases the inactivation yield by OH· radicals. This phenomenon could be due to the formation of compound-I (catalase-H 2 O 2 ) which would be less sensitive towards OH· radicals than catalase. In the presence of 0.1 mol/l ethanol, catalase (5 x 10 -6 mol/l) is not inactived by O 2 - · and RO 2 · (from ethanol) radicals for an irradiation dose of 2000 Gy, implying a complete protecting effect by ethanol [fr

  14. Relationship between oxygen free radicals, cytokines, cortisol and stress complications in patients with acute cerebrovascular disease

    International Nuclear Information System (INIS)

    Zhu Yingbin; Wang Bingjie; Li Yunchao

    2010-01-01

    Objective: To investigate the relationship between oxygen free radicals, cytokines, cortisol and stress complications in patients with acute cerebrovascular disease (ACVD). Methods: Serum levels of superoxide dismutases (SOD), malonaldehyde (MDA) (with biochemistry) interleukin-6 (IL-6), tumor necrosis factor (TNF-α) and cortisol (with RIA) were measured in 32 patients with acute cerebrovascular disease (ACVD) plus stress complications and 48 patients without stress complications as well as 36 controls. Results: Serum SOD contents in non-stressed group were higher than those in stressed group (P<0.05) but lower than those of the controls (P<0.05). However the levels of MDA, IL-6, TNF-α and cortisol were highest in the stressed group and lowest in the controls (all P<0.05). Conclusion: Oxygen free radicals, IL-6, TNF-α and cortisol were involved in stress complications in patients with ACVD. Monitoring the levels of serum SOD, MDA, IL-6, TNF-α and cortisol could be useful for predicting stress complications and evaluating the therapeutic effect. (authors)

  15. ESR Study of the polyvinyl alcohol gamma-ray induced free-radicals

    International Nuclear Information System (INIS)

    Rosas S, E.

    1994-01-01

    This work reports the findings of the molecular weight effect on the electron spin resonance saturation curve of the gamma-ray irradiated polyvinyl alcohol, G-RIPVA. It has been noted that Pva of a lower molecular weight, between 13,000-23,000, show some noticeable differences in the electron spin resonance, ESR, response as a function of the gamma-ray dose in the 1-100 k Gy range than the one reported in the literature with molecular weight of 108,000. Results show a linear response in the log-log plot of the dose vs ESR signal intensity for samples based on G-RIPVA of the lower molecular weight as contrasted with the non-linear ESR response of G-RIPVA of higher molecular weight in the above named dose range. Such a result has been assumed to arise from the shorter molecular chains for the case of the lower molecular weight samples making this to increase the production of Pva free radicals with respect to the absorbed studied doses. Also, a discussion on the nature and stability of the Pva free radicals will be given. (Author)

  16. Addressing Emerging Risks: Scientific and Regulatory Challenges Associated with Environmentally Persistent Free Radicals.

    Science.gov (United States)

    Dugas, Tammy R; Lomnicki, Slawomir; Cormier, Stephania A; Dellinger, Barry; Reams, Margaret

    2016-06-08

    Airborne fine and ultrafine particulate matter (PM) are often generated through widely-used thermal processes such as the combustion of fuels or the thermal decomposition of waste. Residents near Superfund sites are exposed to PM through the inhalation of windblown dust, ingestion of soil and sediments, and inhalation of emissions from the on-site thermal treatment of contaminated soils. Epidemiological evidence supports a link between exposure to airborne PM and an increased risk of cardiovascular and pulmonary diseases. It is well-known that during combustion processes, incomplete combustion can lead to the production of organic pollutants that can adsorb to the surface of PM. Recent studies have demonstrated that their interaction with metal centers can lead to the generation of a surface stabilized metal-radical complex capable of redox cycling to produce ROS. Moreover, these free radicals can persist in the environment, hence their designation as Environmentally Persistent Free Radicals (EPFR). EPFR has been demonstrated in both ambient air PM2.5 (diameter challenges associated with regulating this new, emerging contaminant.

  17. Molecular Mobility of n-Ethylene Glycol Dimethacrylate Glass Formers Upon Free Radical Polymerization

    Science.gov (United States)

    Plaza, Maria Teresa Viciosa

    When a liquid upon cooling avoids crystallization, it enters the supercooled state. If the temperature continues to decrease, the consequent increase of viscosity is reflected in the molecular mobility in such a way that the characteristic relaxation times of cooperative motions become of the same order of the experimentally accessible timescales. Further cooling finally transforms the highly viscous liquid into a glass, in which only local motions are allowed. The monomers n-ethylene glycol dimethacrylate (n-EGDMA) for n =1 to 4, that constitutes the object of this study, easily circumvent crystallization, being good candidates to study the molecular mobility in both supercooled and glassy states. Dielectric Relaxation Spectroscopy (DRS) was the technique chosen to obtain detailed information about their molecular mobility (Chapters 1 and 2). The first part of this work consisted in the dielectric characterization of the relaxation processes present above and below the glass transition temperature (Tg), which shifts to higher values with the molecular weight ( Mw), result confirmed by Differential Scanning Calorimetry (DSC). While the cooperative alpha-process associated to the glass transition, and the secondary beta process, depend on Mw, the other found secondary process, gamma, seems to be independent from this factor (Chapter 3). In the next Chapters different strategies were carried out in order to clarify the mechanisms in the origin of these two secondary relaxations (beta and gamma), and to learn about its respective relation with the main a relaxation. Monitoring the real time isothermal free radical polymerization of TrEGDMA by Temperature Modulated Differential Scanning Calorimetry (TMDSC), carried out at temperatures below the gamma T of the final polymer network, we shown among others two important features: i) the vitrification of the polymer in formation leads to relatively low degrees of conversion, and ii) the unreacted monomer is expelled from

  18. Antioxidant and Free Radical Scavenging Activity of Trigonella foenum-graecum L, Murraya koenigii , Coriandrum sativum and Centella asiatica

    Directory of Open Access Journals (Sweden)

    Sanghamitra Dutta

    2016-04-01

    Full Text Available Antioxidants are naturally occurring substances that combat oxidative damage in biological entities. An antioxidant achieves this by slowing or preventing the oxidation process that can damage cells in the body. It does this by getting oxidized itself in place of the cells. The aim of the present study was to evaluate the in vitro antioxidant and free radical scavenging activities of aqueous and 95% methanol leaf extracts of four herbs viz. Trigonella foenum-graecum L, Murraya koenigii, Coriandrum sativum and Centella asiatica which have frequent use in Indian cuisine. Both aqueous and 95% methanol leaf extracts have shown significant amount reducing power. Both aqueous and 95% methanol leaf extracts of Coriandrum sativum had significant DPPH radical scavenging activity with IC50 value of 0.21± 0.3 mg/L and 0.176 ± 0.008 mg/L respectively. The aqueous leaf extract of Trigonella foenum-graecum L showed low scavenging activity. Among all the leaf extracts, the aqueous leaf extract of Centella asiatica has exhibited significantly high NO radical scavenging activity (80% with IC50 value of 0.11 ± 0.17 mg/L. The aqueous leaf extracts of the samples have showed significantly high superoxide radical scavenging activity. The activity was maximum for the aqueous leaf extract of Centella asiatica, IC50 value is 4.36 ± 0.41 mg/L. anti lipid peroxide activities were very high ( 90 % for aqueous leaf extracts of Coriandrum sativum (IC50 = 0.064 ± 0.85 mg/L and Centella asiatica (IC50 = 0.066 ± 0.9mg/L at a concentration of 0.16 mg/L. The aqueous leaf extracts of the samples were found to contain large amounts of flavonoids and phenolic compounds and exhibited high antioxidant and free radical scavenging activities. These in vitro assays indicate that these plant extracts are significant source of natural antioxidants which might be helpful in preventing the progress of various oxidative stresses.

  19. Free radical generation in post-irradiation period: an evidence from the conversion of xanthine dehydrogenase into xanthine oxidase

    International Nuclear Information System (INIS)

    Kale, R.K.

    2003-01-01

    Xanthine oxidoreductase (XOR) system which consists of xanthine dehydrogenase (XDH) and xathine oxidase (XO), is one of the major sources of free radicals in biological systems. XOR system is pre-dominantly present as XDH in the normal tissue and converts into free radical generating XO-Form in the damaged tissue. Therefore, XO-Form of XOR system, is expected to be mainly found in the radiolytically damaged tissue. In such an event, XO may catalyze the generation of free radicals and potentiate the radiation effects in post-irradiation period. Recent findings on the effect of ionizing radiation on XOR system in the liver of mice, peroxidative damage and lactate dehydrogenase support this possibility. From these results it has been hypothized that free radical generating systems could be activated in the radiolytically damaged cell and in turn contribute to the cause and complications of late effects and their persistence in post-irradiation period. This aspect may have great significance in understanding the radiation - induced damages. It may also have serious implication in various fields like radiation therapy, health physics, carcinogenesis, space travelling radiation exposures and post nuclear accident care. Further, it is suggested that efforts need to be made to search more system(s) which could be activated particularly at lower doses of radiation and generate free radicals in post-irradiation period

  20. Relation between track structure and LET effect on free radical formation for ion beam-irradiated alanine dosimeter

    International Nuclear Information System (INIS)

    Krushev, V.V.; Koizumi, Hitoshi; Ichikawa, Tsuneki; Yoshida, Hiroshi; Shibata, Hiromi; Tagawa, Seiichi; Yoshida, Yoichi

    1994-01-01

    The yield and local concentration of free radicals generated from alanine (α-aminopropionic acid) by irradiation with 3 MeV H + and He + ions were examined by means of electron spin resonance (ESR) and ESR power saturation methods at room temperature. The G-value of the radical formation showed a marked dependence on linear energy transfer (LET) of the ions. The G-value for the H + ion (average LET: 28 eV/nm) was almost the same as that for γ-irradiation and it was smaller by a factor of 1/4.7 for the He + ion (average LET: 225eV/nm). Combining the local concentration of the free radicals along the ion tracks with the G-values and the reported ion range, the radius of a track filled with free radicals was estimated to be 4 ∼ 5 nm by assuming a simple rod-shaped track with a constant radius and homogeneous distribution of the free radicals in it. The track radius scarcely depends on the LET within the range examined. The radiation energy deposited in the core region of the ion track was concluded to spread over the rod to generate free radicals. (author)

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

    Directory of Open Access Journals (Sweden)

    Bruno Moukette Moukette

    2015-01-01

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

  2. In vitro antioxidant capacity and free radical scavenging evaluation of active metabolite constituents of Newbouldia laevis ethanolic leaf extract.

    Science.gov (United States)

    Habu, Josiah Bitrus; Ibeh, Bartholomew Okechukwu

    2015-03-14

    The aim of the present study was to evaluate the in vitro antioxidant and free radical scavenging capacity of bioactive metabolites present in Newbouldia laevis leaf extract. Chromatographic and spectrophotometric methods were used in the study and modified where necessary in the study. Bioactivity of the extract was determined at 10 μg/ml, 50 μg/ml, 100 μg/ml, 200 μg/ml and 400 μg/ml concentrations expressed in % inhibition. The yield of the ethanolic leaf extract of N.laevis was 30.3 g (9.93%). Evaluation of bioactive metabolic constituents gave high levels of ascorbic acid (515.53 ± 12 IU/100 g [25.7 mg/100 g]), vitamin E (26.46 ± 1.08 IU/100 g), saponins (6.2 ± 0.10), alkaloids (2.20 ± 0.03), cardiac glycosides(1.48 ± 0.22), amino acids and steroids (8.01 ± 0.04) measured in mg/100 g dry weight; moderate levels of vitamin A (188.28 ± 6.19 IU/100 g), tannins (0.09 ± 0.30), terpenoids (3.42 ± 0.67); low level of flavonoids (1.01 ± 0.34 mg/100 g) and absence of cyanogenic glycosides, carboxylic acids and aldehydes/ketones. The extracts percentage inhibition of DPPH, hydroxyl radical (OH.), superoxide anion (O2 .-), iron chelating, nitric oxide radical (NO), peroxynitrite (ONOO-), singlet oxygen (1O2), hypochlorous acid (HOCl), lipid peroxidation (LPO) and FRAP showed a concentration-dependent antioxidant activity with no significant difference with the controls. Though, IC50 of the extract showed significant difference only in singlet oxygen (1O2) and iron chelating activity when compared with the controls. The extract is a potential source of antioxidants/free radical scavengers having important metabolites which maybe linked to its ethno-medicinal use.

  3. High density energy storage capacitor

    International Nuclear Information System (INIS)

    Whitham, K.; Howland, M.M.; Hutzler, J.R.

    1979-01-01

    The Nova laser system will use 130 MJ of capacitive energy storage and have a peak power capability of 250,000 MW. This capacitor bank is a significant portion of the laser cost and requires a large portion of the physical facilities. In order to reduce the cost and volume required by the bank, the Laser Fusion Program funded contracts with three energy storage capacitor producers: Aerovox, G.E., and Maxwell Laboratories, to develop higher energy density, lower cost energy storage capacitors. This paper describes the designs which resulted from the Aerovox development contract, and specifically addresses the design and initial life testing of a 12.5 kJ, 22 kV capacitor with a density of 4.2 J/in 3 and a projected cost in the range of 5 cents per joule

  4. Nuclear reaction of 10 B (n, α) 7 Li and grain size effects on the production of free radicals in alanine

    International Nuclear Information System (INIS)

    Zurita Petatan, S.L.

    1993-01-01

    In general, it is important to know the physical and chemical properties of any material that is exposed to ionizing radiation. In particular, in dosimetric work, the amount of the absorbed doses by these materials is of much interest, in such a way that several methods have been developed in the past. An important and quantitatively accessible radiation effect in organic substances is the production of free radicals that can be easily measured by 'ELECTRON PARAMAGNETIC RESONANCE SPECTROSCOPY (EPR)'. Numerous studies have been now been made on pure D L-Alanine irradiated with different radiation sources. Examination of the irradiated samples reveals the production of a stable free radical (CH 3 - CH. -COOH). In particular, gamma and electron irradiated D L-Alanine has received wide attention in the high doses interval (10 - 10 5 Gy). In contrast, there are very few EPR studies on thermal neutron radiation induced free radicals in pure D L-alanine. This may be due to the weak EPR signals observed in the irradiated samples. The objective of this work is to study for the first time the increase of the radical yield produced in neutron irradiated borated alanine by the EPR technique. For this purpose alanine has been mixed with borax in different stoichiometric proportions and grain sizes. When the mixture is neutron irradiated, the boron of the borax may experience a neutron capture reaction, 10 B (n, α) 7 Li. With this nuclear reaction it is supposed that the α particles will may impinge on the alanine molecules, producing in this way extra free radicals. Samples were irradiated in the thermal column of a Triga Mark III nuclear reactor with a thermal neutron flux of 5 x 10 7 n/Cm 2 -s. A signal enhancement of up to 1260 % is observed when samples of alanine-borax were intimately mixed in a stoichiometric ratio of 1:1. We also studied dosimetric characteristics of the mixed samples such as: a) Sensibility. b) Accuracy. c) Traceability. d) Stability. e)Fading. f

  5. HPLC-Analysis of Polyphenolic Compounds in Gardenia jasminoides and Determination of Antioxidant Activity by Using Free Radical Scavenging Assays

    Directory of Open Access Journals (Sweden)

    Riaz Uddin

    2014-05-01

    Full Text Available Purpose: Gardenia jasminoides is a traditional medicinal plant rich in anti-inflammatory flavonoids and phenolic compounds and used for the treatment of inflammatory diseases and pain. In this present study, antioxidant potential of Gardenia jasminoides leaves extract was evaluated by using various antioxidant assays. Methods: Various antioxidant assays such as 1, 1-diphenyl-2-picrylhydrazyl (DPPH radical scavenging assay, reducing power and total antioxidant capacity expressed as equivalent to ascorbic acid were employed. Moreover, phenolic compounds were detected by high-performance liquid chromatography (HPLC coupled with diode-array detection. Results: The methanol extract showed significant free radical scavenging activities in DPPH radical scavenging antioxidant assays compared to the reference antioxidant ascorbic acid. Total antioxidant activity was increased in a dose dependent manner. The extract also showed strong reducing power. The total phenolic content was determined as 190.97 mg/g of gallic acid equivalent. HPLC coupled with diode-array detection was used to identify and quantify the phenolic compounds in the extracts. Gallic acid, (+-catechin, rutin hydrate and quercetin have been identified in the plant extracts. Among the phenolic compounds, catechin and rutin hydrate are present predominantly in the extract. The accuracy and precision of the presented method were corroborated by low intra- and inter-day variations in quantitative results in leaves extract. Conclusion: These results suggest that phenolic compounds and flavonoids might contribute to high antioxidant activities of Gardenia jasminoides leaves.

  6. High-density lipoprotein cholesterol: How High

    Directory of Open Access Journals (Sweden)

    G Rajagopal

    2012-01-01

    Full Text Available The high-density lipoprotein cholesterol (HDL-C is considered anti-atherogenic good cholesterol. It is involved in reverse transport of lipids. Epidemiological studies have found inverse relationship of HDL-C and coronary heart disease (CHD risk. When grouped according to HDL-C, subjects having HDL-C more than 60 mg/dL had lesser risk of CHD than those having HDL-C of 40-60 mg/dL, who in turn had lesser risk than those who had HDL-C less than 40 mg/dL. No upper limit for beneficial effect of HDL-C on CHD risk has been identified. The goals of treating patients with low HDL-C have not been firmly established. Though many drugs are known to improve HDL-C concentration, statins are proven to improve CHD risk and mortality. Cholesteryl ester transfer protein (CETP is involved in metabolism of HDL-C and its inhibitors are actively being screened for clinical utility. However, final answer is still awaited on CETP-inhibitors.

  7. In vitro free radical scavenging activity of ethanolic extract of the whole plant of Evolvulus alsinoides (L.) L.

    Science.gov (United States)

    Gomathi, Duraisamy; Ravikumar, Ganesan; Kalaiselvi, Manokaran; Vidya, Balasubramaniam; Uma, Chandrasekar

    2015-06-01

    To identify the free radical scavenging activity of ethanolic extract of Evolvulus alsinoides. The free radical scavenging activity was evaluated by in vitro methods like reducing power assay, total antioxidant activity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) reduction, superoxide radical scavenging activity, 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS(+)) scavenging activity, hydroxyl radical scavenging assay, and nitric oxide radical scavenging assay, which were studied by using ascorbic acid as standard. The extract showed significant activities in all antioxidant assays compared with the reference antioxidant ascorbic acid. The total antioxidant activity as well as the reducing power was also found to increase in a dose-dependent manner. Evolvulus alsinoides may act as a chemopreventive agent, providing antioxidant properties and offering effective protection from free radicals.

  8. Origin and evolution of the free radical theory of aging: a brief personal history, 1954–2009.

    Science.gov (United States)

    Harman, Denham

    2009-12-01

    Aging is the progressive accumulation in an organism of diverse, deleterious changes with time that increase the chance of disease and death. The basic chemical process underlying aging was first advanced by the free radical theory of aging (FRTA) in 1954: the reaction of active free radicals, normally produced in the organisms, with cellular constituents initiates the changes associated with aging. The involvement of free radicals in aging is related to their key role in the origin and evolution of life. The initial low acceptance of the FRTA by the scientific community, its slow growth, manifested by meetings and occasional papers based on the theory, prompted this account of the intermittent growth of acceptance of the theory over the past nearly 55 years.

  9. Photoprotective effect of vitamins A and E on polyamine and oxygenated free radical metabolism in hairless mouse epidermis.

    Science.gov (United States)

    Khettab, N; Amory, M C; Briand, G; Bousquet, B; Combre, A; Forlot, P; Barey, M

    1988-12-01

    The purpose of this study was to confirm the photoprotective effect on skin of vitamins A and E, due to inhibition of polyamine synthesis and production of free radicals. These variables were measured in the lumbar epidermis of the female hairless mouse subjected to UVA + B irradiation. Polyamines were assayed in epidermal homogenate by HPLC, and production of oxygenated free radicals was determined by spectrofluorometric assay of malonyl dialdehyde. It was determined that butyl-hydroxy-toluene and vitamin E inhibited production of free radicals (56% and 60%, respectively) and caused a significant reduction in polyamine biosynthesis (P less than 0.01), whereas the inhibitory effect of malonyl dialdehyde induced by vitamin A (30%) had no associated effect on polyamine metabolism.

  10. Singlet Oxygen and Free Radical Reactions of Retinoids and Carotenoids—A Review

    Science.gov (United States)

    Truscott, T. George

    2018-01-01

    We report on studies of reactions of singlet oxygen with carotenoids and retinoids and a range of free radical studies on carotenoids and retinoids with emphasis on recent work, dietary carotenoids and the role of oxygen in biological processes. Many previous reviews are cited and updated together with new data not previously reviewed. The review does not deal with computational studies but the emphasis is on laboratory-based results. We contrast the ease of study of both singlet oxygen and polyene radical cations compared to neutral radicals. Of particular interest is the switch from anti- to pro-oxidant behavior of a carotenoid with change of oxygen concentration: results for lycopene in a cellular model system show total protection of the human cells studied at zero oxygen concentration, but zero protection at 100% oxygen concentration. PMID:29301252

  11. Free radical homopolymerization of a vinylferrocene/cyclodextrin complex in water

    Directory of Open Access Journals (Sweden)

    Helmut Ritter

    2010-06-01

    Full Text Available We report the radical initiated homopolymerization of a soluble vinylferrocene cyclodextrin-complex in water. Uncomplexed vinylferrocene 1 and the corresponding homopolymer are hydrophobic and completely insoluble in water. Complexation of 1 with methyl-β-cyclodextrin 2 results in clearly water-soluble structures due to incorporation of the ferrocene moiety into the cyclodextrin cavity. After free radical polymerization of the water-soluble complexed monomer, corresponding to polyvinylferrocene (PVFc, the water-soluble polymer is obtained due to the host guest interactions. Those polymeric complexes are stable in water up to about 90 °C. Above this temperature the polymer precipitates due to decomplexation. The complex was investigated by 1H NMR spectrometry, dynamic light scattering (DLS, differential scanning calorimetry (DSC, and lower critical solution temperature (LCST measurements.

  12. Monte Carlo simulation on kinetics of batch and semi-batch free radical polymerization

    KAUST Repository

    Shao, Jing

    2015-10-27

    Based on Monte Carlo simulation technology, we proposed a hybrid routine which combines reaction mechanism together with coarse-grained molecular simulation to study the kinetics of free radical polymerization. By comparing with previous experimental and simulation studies, we showed the capability of our Monte Carlo scheme on representing polymerization kinetics in batch and semi-batch processes. Various kinetics information, such as instant monomer conversion, molecular weight, and polydispersity etc. are readily calculated from Monte Carlo simulation. The kinetic constants such as polymerization rate k p is determined in the simulation without of “steady-state” hypothesis. We explored the mechanism for the variation of polymerization kinetics those observed in previous studies, as well as polymerization-induced phase separation. Our Monte Carlo simulation scheme is versatile on studying polymerization kinetics in batch and semi-batch processes.

  13. Retinal Diseases Associated with Oxidative Stress and the Effects of a Free Radical Scavenger (Edaravone

    Directory of Open Access Journals (Sweden)

    Tomomi Masuda

    2017-01-01

    Full Text Available Oxidative stress plays a pivotal role in developing and accelerating retinal diseases including age-related macular degeneration (AMD, glaucoma, diabetic retinopathy (DR, and retinal vein occlusion (RVO. An excess amount of reactive oxygen species (ROS can lead to functional and morphological impairments in retinal pigment epithelium (RPE, endothelial cells, and retinal ganglion cells (RGCs. Here we demonstrate that edaravone, a free radical scavenger, decreased apoptotic cell death, oxidative damage to DNA and lipids, and angiogenesis through inhibiting JNK and p38 MAPK pathways in AMD, glaucoma, DR, and RVO animal models. These data suggest that the therapeutic strategy for targeting oxidative stress may be important for the treatment of these ocular diseases, and edaravone may be useful for treating retinal diseases associated with oxidative stress.

  14. Retinal Diseases Associated with Oxidative Stress and the Effects of a Free Radical Scavenger (Edaravone)

    Science.gov (United States)

    Hara, Hideaki

    2017-01-01

    Oxidative stress plays a pivotal role in developing and accelerating retinal diseases including age-related macular degeneration (AMD), glaucoma, diabetic retinopathy (DR), and retinal vein occlusion (RVO). An excess amount of reactive oxygen species (ROS) can lead to functional and morphological impairments in retinal pigment epithelium (RPE), endothelial cells, and retinal ganglion cells (RGCs). Here we demonstrate that edaravone, a free radical scavenger, decreased apoptotic cell death, oxidative damage to DNA and lipids, and angiogenesis through inhibiting JNK and p38 MAPK pathways in AMD, glaucoma, DR, and RVO animal models. These data suggest that the therapeutic strategy for targeting oxidative stress may be important for the treatment of these ocular diseases, and edaravone may be useful for treating retinal diseases associated with oxidative stress. PMID:28194256

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

    Directory of Open Access Journals (Sweden)

    Lilian Regina Barros Mariutti

    2008-12-01

    Full Text Available Ethanolic extracts from 23 different dried herbs and spices commercialized in Brazil were investigated for their free radical scavenging properties using the stable free radicals 2,2'-diphenyl-β-picrylhydrazyl (DPPH• and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS•+, and Trolox as reference (TEAC for both radicals. The kinetic curves for both radicals showed to follow the first order kinetics model and the decay rate constant (k obs was calculated. For all the samples, the two methods showed a good linear TEAC correlation, indicating that the average reactivity of the compounds present in the ethanolic extracts was similar. Sage and rosemary extracts showed the highest free radical scavenging capacities, while onion showed negligible activity and colorifico, one of the most consumed spices in Brazil, showed low ABTS•+ scavenging activity. Three distinct situations were found for the extracts concerning the DPPH• scavenging capacities: (1 extracts, like rosemary and laurel, that presented the same efficient concentrations (EC50 but differed in the TEAC values and velocities of action (k obs, (2 extracts, such as garlic and basil, that showed similar EC50 and TEAC values, but different k obs values and (3 extracts that reacted at the same velocities but completely differed in the free radical scavenging capacities, like black pepper, savory, nutmeg, rosemary and sage. Similar considerations could be done for the ABTS•+ results. For the first time the ABTS•+ scavenging activity for allspice, basil, cardamom, chives, colorifico, cumin, dill, laurel, marjoram, parsley and tarragon was reported.Extratos etanólicos de 23 ervas e condimentos desidratados comercializados no Brasil foram analisados quanto as suas propriedades antioxidantes utilizando os radicais 2,2'-difenil-β-picrilhidrazil (DPPH• e ácido 2,2'-azino-bis(3-etilbenzotiazolina-6-sulfônico (ABTS•+, Trolox foi usado como referência para ambos radicais

  16. The first report of a muoniated free radical formed from reaction of Mu with Br2

    International Nuclear Information System (INIS)

    Ghandi, Khashayar; Cottrell, Stephen P.; Fleming, Donald; Johnson, Clive

    2006-01-01

    In this paper, we report preliminary data for the first direct evidence of a free radical formed from Mu reactivity with Br 2 in the gas phase, in N 2 moderator at a total pressure of 3 bar. A new experimental setup and target vessel for μSR studies of reactive compounds, such as the halogens and hydrogen halides, suitable as well for RF measurements, is described. The experimental data, obtained from a longitudinal field repolarization curve, yields a hfc of 1770 MHz. We tentatively identify this as the [BrMuBr] radical, a non-conventional bond system, arising from the combination of a van der Waals interaction and dynamics on a repulsive surface. Studies of the dynamics and hfcs of possible radicals, which in principal could form, are also outlined here

  17. Free radicals formed by H(Mu) addition to triphenylene and dodecahydrotriphenylene

    Energy Technology Data Exchange (ETDEWEB)

    Brodovitch, Jean-Claude [TRIUMF and Department of Chemistry, 8888 University Drive, Simon Fraser University, Burnaby B.C., V5A 1S6 (Canada); Ghandi, Khashayar [TRIUMF and Department of Chemistry, 8888 University Drive, Simon Fraser University, Burnaby B.C., V5A 1S6 (Canada); McKenzie, Iain [TRIUMF and Department of Chemistry, 8888 University Drive, Simon Fraser University, Burnaby B.C., V5A 1S6 (Canada); Percival, Paul W. [TRIUMF and Department of Chemistry, 8888 University Drive, Simon Fraser University, Burnaby B.C., V5A 1S6 (Canada)]. E-mail: percival@sfu.ca; Schueth, Joachim [TRIUMF and Department of Chemistry, 8888 University Drive, Simon Fraser University, Burnaby B.C., V5A 1S6 (Canada)

    2006-03-31

    Muonium has been used as an H atom analogue to investigate the free radicals formed by H addition to the fused polyaromatic hydrocarbon triphenylene. Although there are three inequivalent sites of attack in this molecule, only two radicals were detected. Muon and proton hyperfine constants were determined by transverse field {mu}SR and LCR, respectively. With the help of quantum calculations, all the signals can be assigned to radicals formed by Mu addition to C-H sites, while there is no evidence for addition to the tertiary carbons at ring junctions. To force attack on a tertiary carbon, a complementary study was conducted on the dodecahydrotriphenylene molecule. As expected, only one radical is formed. From LCR measurements the number of non-equivalent protons are interpreted as the results of the conformational effect of the saturated side rings.

  18. Free radicals formed by H(Mu) addition to triphenylene and dodecahydrotriphenylene

    International Nuclear Information System (INIS)

    Brodovitch, Jean-Claude; Ghandi, Khashayar; McKenzie, Iain; Percival, Paul W.; Schueth, Joachim

    2006-01-01

    Muonium has been used as an H atom analogue to investigate the free radicals formed by H addition to the fused polyaromatic hydrocarbon triphenylene. Although there are three inequivalent sites of attack in this molecule, only two radicals were detected. Muon and proton hyperfine constants were determined by transverse field μSR and LCR, respectively. With the help of quantum calculations, all the signals can be assigned to radicals formed by Mu addition to C-H sites, while there is no evidence for addition to the tertiary carbons at ring junctions. To force attack on a tertiary carbon, a complementary study was conducted on the dodecahydrotriphenylene molecule. As expected, only one radical is formed. From LCR measurements the number of non-equivalent protons are interpreted as the results of the conformational effect of the saturated side rings

  19. Free radical scavenging activity and lipoxygenase inhibition of Mahonia aquifolium extract and isoquinoline alkaloids

    Directory of Open Access Journals (Sweden)

    Kettmann Viktor

    2007-07-01

    Full Text Available Abstract Roots and stem-bark of Mahonia aquifolium (Oregon grape (Berberidaceae are effectively used in the treatment of skin inflammatory conditions. In the present study, the effect of Mahonia aquifolium crude extract and its two representative alkaloid fractions containing protoberberine and bisbenzylisoquinoline (BBIQ alkaloids on activity of 12-lipoxygenase (12-LOX, was studied. The reactivity with 1,1-diphenyl-2-picryl-hydrazyl (DPPH, a free stable radical, was evaluated to elucidate the rate of possible lipid-derived radical scavenging in the mechanism of the enzyme inhibition. The results indicate that although the direct radical scavenging mechanism cannot be ruled out in the lipoxygenase inhibition by Mahonia aquifolium and its constituents, other mechanisms based on specific interaction between enzyme and alkaloids could play the critical role in the lipoxygenase inhibition rather than non-specific reactivity with free radicals.

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

    International Nuclear Information System (INIS)

    Kantoglu, O.; Ozbey, T.; Gueven, O.

    1995-01-01

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

  1. Melatonin and Structurally-Related Compounds Protect Synaptosomal Membranes from Free Radical Damage

    Directory of Open Access Journals (Sweden)

    María A. Sáenz

    2010-01-01

    Full Text Available Since biological membranes are composed of lipids and proteins we tested the in vitro antioxidant properties of several indoleamines from the tryptophan metabolic pathway in the pineal gland against oxidative damage to lipids and proteins of synaptosomes isolated from the rat brain. Free radicals were generated by incubation with 0.1 mM FeCl3, and 0.1 mM ascorbic acid. Levels of malondialdehyde (MDA plus 4-hydroxyalkenal (4-HDA, and carbonyl content in the proteins were measured as indices of oxidative damage to lipids and proteins, respectively. Pinoline was the most powerful antioxidant evaluated, with melatonin, N-acetylserotonin, 5-hydroxytryptophan, 5-methoxytryptamine, 5-methoxytryptophol, and tryptoline also acting as antioxidants.

  2. Infrared Absorption Spectroscopy and Chemical Kinetics of Free Radicals, Final Technical Report

    Science.gov (United States)

    Curl, Robert F.; Glass, Graham P.

    2004-11-01

    This research was directed at the detection, monitoring, and study of the chemical kinetic behavior by infrared absorption spectroscopy of small free radical species thought to be important intermediates in combustion. Work on the reaction of OH with acetaldehyde has been completed and published and work on the reaction of O({sup 1}D) with CH{sub 4} has been completed and submitted for publication. In the course of our investigation of branching ratios of the reactions of O({sup 1}D) with acetaldehyde and methane, we discovered that hot atom chemistry effects are not negligible at the gas pressures (13 Torr) initially used. Branching ratios of the reaction of O({sup 1}D) with CH{sub 4} have been measured at a tenfold higher He flow and fivefold higher pressure.

  3. Rate constants for the reactions of free radicals with oxygen in solution

    International Nuclear Information System (INIS)

    Maillard, B.; Ingold, K.U.; Scaiano, J.C.

    1983-01-01

    The kinetics of the rections of several free radicals with oxygen have been examined in solution at 300 K using laser flash photolysis techniques. The reactions of resonance-stabilized radicals are only slightly slower than those of nonstabilized radicals: for example, for tert-butyl (in cyclohexane), 4.93 x 10 9 ; benzyl, 2.36 x 10 9 (in cyclohexane); cyclohexadienyl (in benzene), 1.64 x 10 9 M -1 s -1 . The reaction of butyl-tin (n-Bu 3 Sn.) radicals is unusually fast (7.5 x 10 9 M -1 s -1 ), a fact that has been tentatively attributed to a relaxation of spin selection rules due to heavy atom effects. 1 table

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

    Directory of Open Access Journals (Sweden)

    Radhakrishnan Ammu

    2010-09-01

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

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

    Science.gov (United States)

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

    2013-01-01

    Gnidia glauca and Dioscorea bulbifera are traditional medicinal plants that can be considered as sources of natural antioxidants. Herein we report the phytochemical analysis and free radical scavenging activity of their sequential extracts. Phenolic and flavonoid content were determined. Scavenging activity was checked against pulse radiolysis generated ABTS•+ and OH radical, in addition to DPPH, superoxide and hydroxyl radicals by biochemical methods followed by principal component analysis. G. glauca leaf extracts were rich in phenolic and flavonoid content. Ethyl acetate extract of D. bulbifera bulbs and methanol extract of G. glauca stem exhibited excellent scavenging of pulse radiolysis generated ABTS•+ radical with a second order rate constant of 2.33×106 and 1.72×106, respectively. Similarly, methanol extract of G. glauca flower and ethyl acetate extract of D. bulbifera bulb with second order rate constants of 4.48×106 and 4.46×106 were found to be potent scavengers of pulse radiolysis generated OH radical. G. glauca leaf and stem showed excellent reducing activity and free radical scavenging activity. HPTLC fingerprinting, carried out in mobile phase, chloroform: toluene: ethanol (4: 4: 1, v/v) showed presence of florescent compound at 366 nm as well as UV active compound at 254 nm. GC-TOF-MS analysis revealed the predominance of diphenyl sulfone as major compound in G. glauca. Significant levels of n-hexadecanoic acid and octadecanoic acid were also present. Diosgenin (C27H42O3) and diosgenin (3á,25R) acetate were present as major phytoconstituents in the extracts of D. bulbifera. G. glauca and D. bulbifera contain significant amounts of phytochemicals with antioxidative properties that can be exploited as a potential source for herbal remedy for oxidative stress induced diseases. These results rationalize further investigation in the potential discovery of new natural bioactive principles from these two important medicinal plants. PMID:24367520

  6. Free radical reactions of isoxazole and pyrazole derivatives of hispolon: kinetics correlated with molecular descriptors.

    Science.gov (United States)

    Shaikh, Shaukat Ali M; Barik, Atanu; Singh, Beena G; Modukuri, Ramani V; Balaji, Neduri V; Subbaraju, Gottumukkala V; Naik, Devidas B; Priyadarsini, K Indira

    2016-12-01

    Hispolon (HS), a natural polyphenol found in medicinal mushrooms, and its isoxazole (HI) and pyrazole (HP) derivatives have been examined for free radical reactions and in vitro antioxidant activity. Reaction of these compounds with one-electron oxidant, azide radicals ([Formula: see text]) and trichloromethyl peroxyl radicals ([Formula: see text]), model peroxyl radicals, studied by nanosecond pulse radiolysis technique, indicated formation of phenoxyl radicals absorbing at 420 nm with half life of few hundred microseconds (μs). The formation of phenoxyl radicals confirmed that the phenolic OH is the active centre for free radical reactions. Rate constant for the reaction of these radicals with these compounds were in the order k HI ≅ k HP  >   k HS . Further the compounds were examined for their ability to inhibit lipid peroxidation in model membranes and also for the scavenging of 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical and superoxide ([Formula: see text]) radicals. The results suggested that HP and HI are less efficient than HS towards these radical reactions. Quantum chemical calculations were performed on these compounds to understand the mechanism of reaction with different radicals. Lower values of adiabatic ionization potential (AIP) and elevated highest occupied molecular orbital (HOMO) for HI and HP compared with HS controlled their activity towards [Formula: see text] and [Formula: see text] radicals, whereas the contribution of overall anion concentration was responsible for higher activity of HS for DPPH, [Formula: see text], and lipid peroxyl radical. The results confirm the role of different structural moieties on the antioxidant activity of hispolon derivatives.

  7. MRI of Retinal Free Radical Production With Laminar Resolution In Vivo

    Science.gov (United States)

    Berkowitz, Bruce A.; Lewin, Alfred S.; Biswal, Manas R.; Bredell, Bryce X.; Davis, Christopher; Roberts, Robin

    2016-01-01

    Purpose Recent studies have suggested the hypothesis that quench-assisted 1/T1 magnetic resonance imaging (MRI) measures free radical production with laminar resolution in vivo without the need of a contrast agent. Here, we test this hypothesis further by examining the spatial and detection sensitivity of quench-assisted 1/T1 MRI to strain, age, or retinal cell layer-specific genetic manipulations. Methods We studied: adult wild-type mice; mice at postnatal day 7 (P7); cre dependent retinal pigment epithelium (RPE)-specific MnSOD knockout mice; doxycycline-treated Sod2flox/flox mice lacking the cre transgene; and α-transducin knockout (Gnat1−/−) mice on a C57Bl/6 background. Transretinal 1/T1 profiles were mapped in vivo in the dark without or with antioxidant treatment, or followed by light exposure. We calibrated profiles spatially using optical coherence tomography. Results Dark-adapted RPE-specific MnSOD knockout mice had greater than normal 1/T1 in the RPE and outer nuclear layers that was corrected to wild-type levels by antioxidant treatment. Dark and light Gnat1−/− mice also had greater than normal outer retinal 1/T1 values. In adult wild-type mice, dark values of 1/T1 in the ellipsoid region and in the outer segment were suppressed by 13 minutes of light. By 29 minutes of light, 1/T1 reduction extended to the outer nuclear layer. Gnat1−/− mice demonstrated a faster light-evoked suppression of 1/T1 values in the outer retina. In P7 mice, transretinal 1/T1 profiles were the same in dark and light. Conclusions Quench-assisted MRI has the laminar resolution and detection sensitivity to evaluate normal and pathologic production of free radicals in vivo. PMID:26886890

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

    Directory of Open Access Journals (Sweden)

    Wagner Brett A

    2010-08-01

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

  9. Effect of free radical scavenger, edaravone, for patients with carbon monoxide poisoning.

    Science.gov (United States)

    Mori, Kiyofumi; Beppu, Takaaki; Fujisawa, Yutaka; Onodera, Makoto; Ogasawara, Kuniaki; Sasaki, Makoto; Ehara, Shigeru; Sakai, Akio; Endo, Shigeatsu

    2015-12-01

    Chronic neurological symptoms after carbon monoxide (CO) poisoning are caused by various biological processes in the damaged brain, with free radicals playing roles as mediators in establishing pathological processes leading to chronic neurological symptoms under CO poisoning. This study aimed to clarify the effects of a free radical scavenger, edaravone, in patients with CO poisoning. We retrospectively compared two groups comprising patients treated with hyperbaric oxygenation alone (Group A, n=25) or edaravone in addition to hyperbaric oxygenation (Group B, n=25). Edaravone was administrated intravenously at 30 mg every 12h for 7 days. Patient characteristics, general conditions on admission, and frequency of chronic neurological symptoms were compared between groups. Among patients showing chronic neurological symptoms, cognitive function and daily activity were also compared between groups. No significant differences in characteristics or general conditions on admission were identified between groups. In Group B, no patients presented with marked complications caused by edaravone. Although chronic persisting symptoms were less frequent in Group B (n=1, 0.04%) than in Group A (n=5, 20%), this difference was not significant. In the 11 patients showing chronic symptoms, scores for cognitive function and daily activity in the chronic phase were better in Group B than in Group A, but no significant differences were apparent. The present results suggest that edaravone represents a tolerable and feasible treatment for CO-poisoned patients. Further studies are needed to clarify whether edaravone can favorably influence chronic neurological symptoms caused by CO poisoning. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Free radical scavenger, edaravone, reduces the lesion size of lacunar infarction in human brain ischemic stroke

    Science.gov (United States)

    2011-01-01

    Background Although free radicals have been reported to play a role in the expansion of ischemic brain lesions, the effect of free radical scavengers is still under debate. In this study, the temporal profile of ischemic stroke lesion sizes was assessed for more than one year to evaluate the effect of edaravone which might reduce ischemic damage. Methods We sequentially enrolled acute ischemic stroke patients, who admitted between April 2003 and March 2004, into the edaravone(-) group (n = 83) and, who admitted between April 2004 and March 2005, into the edaravone(+) group (n = 93). Because, edaravone has been used as the standard treatment after April 2004 in our hospital. To assess the temporal profile of the stroke lesion size, the ratio of the area [T2-weighted magnetic resonance images (T2WI)/iffusion-weighted magnetic resonance images (DWI)] were calculated. Observations on T2WI were continued beyond one year, and observational times were classified into subacute (1-2 months after the onset), early chronic (3-6 month), late chronic (7-12 months) and old (≥13 months) stages. Neurological deficits were assessed by the National Institutes of Health Stroke Scale upon admission and at discharge and by the modified Rankin Scale at 1 year following stroke onset. Results Stroke lesion size was significantly attenuated in the edaravone(+) group compared with the edaravone(-) group in the period of early and late chronic observational stages. However, this reduction in lesion size was significant within a year and only for the small-vessel occlusion stroke patients treated with edaravone. Moreover, patients with small-vessel occlusion strokes that were treated with edaravone showed significant neurological improvement during their hospital stay, although there were no significant differences in outcome one year after the stroke. Conclusion Edaravone treatment reduced the volume of the infarct and improved neurological deficits during the subacute period, especially

  11. Free radical scavenger, edaravone, reduces the lesion size of lacunar infarction in human brain ischemic stroke

    Directory of Open Access Journals (Sweden)

    Suzuki Akifumi

    2011-03-01

    Full Text Available Abstract Background Although free radicals have been reported to play a role in the expansion of ischemic brain lesions, the effect of free radical scavengers is still under debate. In this study, the temporal profile of ischemic stroke lesion sizes was assessed for more than one year to evaluate the effect of edaravone which might reduce ischemic damage. Methods We sequentially enrolled acute ischemic stroke patients, who admitted between April 2003 and March 2004, into the edaravone(- group (n = 83 and, who admitted between April 2004 and March 2005, into the edaravone(+ group (n = 93. Because, edaravone has been used as the standard treatment after April 2004 in our hospital. To assess the temporal profile of the stroke lesion size, the ratio of the area [T2-weighted magnetic resonance images (T2WI/iffusion-weighted magnetic resonance images (DWI] were calculated. Observations on T2WI were continued beyond one year, and observational times were classified into subacute (1-2 months after the onset, early chronic (3-6 month, late chronic (7-12 months and old (≥13 months stages. Neurological deficits were assessed by the National Institutes of Health Stroke Scale upon admission and at discharge and by the modified Rankin Scale at 1 year following stroke onset. Results Stroke lesion size was significantly attenuated in the edaravone(+ group compared with the edaravone(- group in the period of early and late chronic observational stages. However, this reduction in lesion size was significant within a year and only for the small-vessel occlusion stroke patients treated with edaravone. Moreover, patients with small-vessel occlusion strokes that were treated with edaravone showed significant neurological improvement during their hospital stay, although there were no significant differences in outcome one year after the stroke. Conclusion Edaravone treatment reduced the volume of the infarct and improved neurological deficits during the subacute

  12. ESR detection of free radicals produced in irradiated fresh fruits and dried foods

    International Nuclear Information System (INIS)

    Bustos G, E.; Gomes, V.; Garcia, F.; Azorin, J.

    2007-01-01

    Full text: Electron spin resonance (ESR) technique was used to measure the stability of free radicals produced by the irradiation treatment in mangoes and in four spices: black pepper, oregano, 'guajillo' chili and 'morron' chili. The ESR spectra for mangoes were scanned in three different parts from the seeds and were recorded in fresh and dried tissues. The ESR spectra in fresh tissue of no irradiated mangoes, were a sextet line signal produced by Mn 2+ ion and a singlet centered at g = 2.00 produced by the endogenous radical. New resonances were observed in the irradiated samples at 1.5 mT and 3 mT respects to the center line for right and left side. These new resonance signals were-observed for eight days in mangoes treated at 1.00 kGy, and for three days at 0.15 kGy. The resonance due to the irradiation was observed in Iyophilized mangoes only one day after the treatment, in the vacuum dried samples, no new resonances were observed. The triplet signal, as well as the central single line appeared after irradiation in black pepper, morron chili and guajillo chili. These signals were also observed in the irradiated spices at any radiation dose higher than 1.0 kGy. The signals decrease promptly, in ten days after the 'irradiation. It was not possible to observe the triplet signal in oregano, even when the samples were analyzed immediately after irradiation treatment. The only signal observed in irradiated spice was the endogenous radical. This signal increased as the radiation dose increased and decreased during storage time at room temperature. Results showed that free radicals produced in irradiated fresh fruits or dried foods have a quick recombination. It was observed that in the spices the signal remains for several weeks meanwhile only eight days in mangoes. (Author)

  13. Role of oxygen free radicals in the proliferation of myofibroblasts induced by AngII

    Directory of Open Access Journals (Sweden)

    Liying Wang

    2013-02-01

    Full Text Available Previous studies have demonstrated the important role of angiotension II (AngII in promoting proliferation of myofibroblasts (myoFbs and myocardial fibrosis. However, the underlying mechanisms and the role of oxygen free radicals in the proliferation of myofibroblasts induced by AngII are unclear. The present study was designed to shed light on this issue through exploration of AngII signaling pathways via in vitro experiments. Primary cultures of neonatal rat myoFbs were divided into five groups which were treated with AngII (10−8 to 10−6 M, AngII with the antioxidant N-acetyl-L-cysteine (NAC, or normal culture medium. We observed the proliferation of myoFbs as induced by AngII at different concentrations with MTT. Reactive oxygen species (ROS levels in myoFbs were detected by monitoring the fluorescence of 2′,7′-dichlorofluorescein. The contents and levels of oxygen free radicals (OH· in the three groups were detected by spectrophotometer, immunocytochemical staining, and confocal fluorescence. Western blot and image analysis were used to measure membrane translocation and expression of phospho-protein kinase Cα. MyoFbs incubated with AngII (10−8 to 10−6 M for 24 h increased their rate of proliferation, the content of OH·, and expression of ROS (P<0.01 vs. control group, whereas these parameters decreased in the presence of NAC. Immunocytochemistry, confocal fluorescence staining and image analysis showed that AngII could promote the translocation and expression of p-PKCα in membrane, and the antioxidant NAC blocked this increase (P<0.01. Western blot results also showed that NAC could inhibit the expression of p-PKCα.

  14. Epigenetic oxidative redox shift (EORS) theory of aging unifies the free radical and insulin signaling theories.

    Science.gov (United States)

    Brewer, Gregory J

    2010-03-01

    Harman's free radical theory of aging posits that oxidized macromolecules accumulate with age to decrease function and shorten life-span. However, nutritional and genetic interventions to boost anti-oxidants have generally failed to increase life-span. Furthermore, the free radical theory fails to explain why exercise causes higher levels of oxyradical damage, but generally promotes healthy aging. The separate anti-aging paradigms of genetic or caloric reductions in the insulin signaling pathway is thought to slow the rate of living to reduce metabolism, but recent evidence from Westbrook and Bartke suggests metabolism actually increases in long-lived mice. To unify these disparate theories and data, here, we propose the epigenetic oxidative redox shift (EORS) theory of aging. According to EORS, sedentary behavior associated with age triggers an oxidized redox shift and impaired mitochondrial function. In order to maintain resting energy levels, aerobic glycolysis is upregulated by redox-sensitive transcription factors. As emphasized by DeGrey, the need to supply NAD(+) for glucose oxidation and maintain redox balance with impaired mitochondrial NADH oxidoreductase requires the upregulation of other oxidoreductases. In contrast to the 2% inefficiency of mitochondrial reduction of oxygen to the oxyradical, these other oxidoreductases enable glycolytic energy production with a deleterious 100% efficiency in generating oxyradicals. To avoid this catastrophic cycle, lactate dehydrogenase is upregulated at the expense of lactic acid acidosis. This metabolic shift is epigenetically enforced, as is insulin resistance to reduce mitochondrial turnover. The low mitochondrial capacity for efficient production of energy reinforces a downward spiral of more sedentary behavior leading to accelerated aging, increased organ failure with stress, impaired immune and vascular functions and brain aging. Several steps in the pathway are amenable to reversal for exit from the vicious

  15. Chemical Composition, In Vitro Antimicrobial, Free-Radical-Scavenging and Antioxidant Activities of the Essential Oil of Leucas inflata Benth

    Directory of Open Access Journals (Sweden)

    Ramzi A. Mothana

    2017-02-01

    Full Text Available The essential oil of Leucas inflata Balf.f. (Lamiaceae, collected in Yemen, was analyzed using gas chromatography (GC and gas chromatography-mass spectrometry (GC-MS techniques. Forty-three components were recognized, representing 89.2% of the total oil. The L. inflata volatile oil was found to contain a high percentage of aliphatic acids (51.1%. Hexadecanoic acid (32.8% and n-dodecanoic acid (7.8% were identified as the major compounds. Oxygenated monoterpenes were distinguished as the second significant group of constituents (16.0%. Camphor (6.1% and linalool (3.2% were found to be the main components among the oxygenated monoterpenes. In addition, the volatile oil was assessed for its antimicrobial activity against four bacterial strains and one yeast species using broth micro-dilution assay for minimum inhibitory concentrations (MIC. In addition, antioxidant activity was measured utilizing the anti-radical activity of the sable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH and β-Carotene-linoleic acid assays. The oil of L. inflata showed an excellent antibacterial activity against only the tested Gram-positive bacteria with a MIC-value of 0.81 mg/mL. Furthermore, the oil demonstrated, at a concentration of 1 mg/mL, a weak to moderate antiradical and antioxidant activity of 38% and 32%, respectively.

  16. Bromine isotopic signature facilitates de novo sequencing of peptides in free-radical-initiated peptide sequencing (FRIPS) mass spectrometry.

    Science.gov (United States)

    Nam, Jungjoo; Kwon, Hyuksu; Jang, Inae; Jeon, Aeran; Moon, Jingyu; Lee, Sun Young; Kang, Dukjin; Han, Sang Yun; Moon, Bongjin; Oh, Han Bin

    2015-02-01

    We recently showed that free-radical-initiated peptide sequencing mass spectrometry (FRIPS MS) assisted by the remarkable thermochemical stability of (2,2,6,6-tetramethyl-piperidin-1-yl)oxyl (TEMPO) is another attractive radical-driven peptide fragmentation MS tool. Facile homolytic cleavage of the bond between the benzylic carbon and the oxygen of the TEMPO moiety in o-TEMPO-Bz-C(O)-peptide and the high reactivity of the benzylic radical species generated in •Bz-C(O)-peptide are key elements leading to extensive radical-driven peptide backbone fragmentation. In the present study, we demonstrate that the incorporation of bromine into the benzene ring, i.e. o-TEMPO-Bz(Br)-C(O)-peptide, allows unambiguous distinction of the N-terminal peptide fragments from the C-terminal fragments through the unique bromine doublet isotopic signature. Furthermore, bromine substitution does not alter the overall radical-driven peptide backbone dissociation pathways of o-TEMPO-Bz-C(O)-peptide. From a practical perspective, the presence of the bromine isotopic signature in the N-terminal peptide fragments in TEMPO-assisted FRIPS MS represents a useful and cost-effective opportunity for de novo peptide sequencing. Copyright © 2015 John Wiley & Sons, Ltd.

  17. Damage of polyesters by the atmospheric free radical oxidant NO3 •: a product study involving model systems

    Science.gov (United States)

    Goeschen, Catrin

    2013-01-01

    Summary Manufactured polymer materials are used in increasingly demanding applications, but their lifetime is strongly influenced by environmental conditions. In particular, weathering and ageing leads to dramatic changes in the properties of the polymers, which results in decreased service life and limited usage. Despite the heavy reliance of our society on polymers, the mechanism of their degradation upon exposure to environmental oxidants is barely understood. In this work, model systems of important structural motifs in commercial high-performing polyesters were used to study the reaction with the night-time free radical oxidant NO3 • in the absence and presence of other radical and non-radical oxidants. Identification of the products revealed ‘hot spots’ in polyesters that are particularly vulnerable to attack by NO3 • and insight into the mechanism of oxidative damage by this environmentally important radical. It is suggested that both intermediates as well as products of these reactions are potentially capable of promoting further degradation processes in polyesters under environmental conditions. PMID:24204400

  18. In Vitro Propagation, Phytochemical Analysis, and Evaluation of Free Radical Scavenging Property of Scrophularia kakudensis Franch Tissue Extracts.

    Science.gov (United States)

    Manivannan, Abinaya; Soundararajan, Prabhakaran; Park, Yoo Gyeong; Jeong, Byoung Ryong

    2015-01-01

    The current study deals with in vitro propagation, antioxidant property estimation, and assessment of acacetin content in Scrophularia kakudensis Franch. Adventitious shoot induction was achieved from the nodal explant with the highest number of adventitious shoots per explant (17.4) on Murashige and Skoog's (MS) medium fortified with 2.0 mg·L(-1) 6-benzyladenine (BA) and 0.5 mg L(-1) indole-3-acetic acid (IAA). Maximum number of roots per plant (16.5) was noted in half strength MS medium supplemented with 0.5 mg·L(-1) IAA. The regenerated plants displayed successful survival ratio (95%) in the greenhouse. The highest content of acacetin, a pharmaceutically important flavonoid, was observed in the shoot extracts (in vitro: 32.83 µg·g(-1) FW; in vivo: 30.05 µg·g(-1) FW) followed by root extracts. Total phenol and flavonoid contents along with free radical scavenging assays revealed the occurrence of larger amount of antioxidants in shoot extract in comparison with callus and root extracts of S. kakudensis. Thus, the outcome of the present study can be highly beneficial for the germplasm conservation and commercial cultivation of S. kakudensis for therapeutic purposes.

  19. Developments in laser-induced fluorescence spectroscopy for quantitative in situ measurements of free radicals in the troposphere

    Science.gov (United States)

    Heard, Dwayne

    2015-04-01

    Photo-oxidation in the troposphere is highly complex, being initiated by short lived free radical species, in the daytime dominated by the hydroxyl radical, OH. Chemical oxidation cycles, which also involve peroxy radicals (HO2 and RO2), remove natural or anthropogenic emissions (for example methane) and generate a range of secondary products, for example ozone, nitrogen dioxide, acidic and multifunctional organic species, and secondary organic aerosol, which impact on human health and climate. Owing to their short lifetime in the atmosphere, the abundance of radicals is determined solely by their rate of chemical production and loss, and not by transport. Field measurements of the concentrations of radicals and comparison with calculations using a numerical model therefore constitutes one of the very best ways to test whether the chemistry in each of these locations is understood and accurately represented in the model. Validation of the chemistry is important, as the predictions of climate and air quality models containing this chemistry are used to drive the formulation of policy and legislation. However, in situ measurements of radical species, owing to their very low abundance (often sub part per trillion) and short lifetimes (pulse repetition rate tunable laser systems, will be discussed, together with calibration methods to make signals absolute, and identification of potential interferences. LIF instruments have been operated on ground, ship and aircraft platforms at a number of locations worldwide, and examples from recent fieldwork involving the Leeds instruments will be presented.

  20. Reactions of organic free radicals at colloidal silver in aqueous solution. Electron pool effect and water decomposition

    International Nuclear Information System (INIS)

    Henglein, A.

    1979-01-01

    Organic free radicals of high negative redox potential such as α-alcohol radicals were found to transfer electrons to colloidal silver particles stabilized by sodium dodecyl sulfate in aqueous solution. The colloidal particles thus became a pool of stored electrons that could reduce water to form hydrogen or react with suitable acceptors in solution. The organic radicals were produced by irradiation, using suitable scavengers for the primary radicals from the radiolysis of the aqueous solvent. The solutions initially contained silver ions at 1 x 10 -4 - 2 x 10 -3 M. At doses below 10 5 rd, the silver ions were completely reduced to form the colloidal catalyst. In this dose range, the corresponding hydrogen yield amounted to 1 molecule per 100 eV. It increased steeply at higher doses up to 3 molecules per 100 eV. The H 2 yield decreased with increasing dose rate and with increasing pH in alkaline solutions. It was highest at a concentration of sodium dodecyl sulfate of 1 x 10 -3 M, i.e., far below the critical micelle concentration of this surfactant. Changes in the absorption spectrum of the colloid are attributed to changes in the size of the silver particles upon charging up with electrons. The competition of radical-colloid reactions with radical-radical deactivation in the bulk of solution or at the surface of the colloidal particles is also discussed. 11 figures

  1. Free radicals in pyrimidines: ESR of. gamma. -irradiated 5-cyclohexenyl-1,5-dimethyl barbituric acid. [/sup 60/Co

    Energy Technology Data Exchange (ETDEWEB)

    Benson, B. (Lehigh Univ., Bethlehem, PA); Erich, L.

    1981-06-01

    ESR studies have determined that ionizing radiation damage of hexobarbital (5-cyclohexenyl-1,5-dimethylbarbituric acid) causes the formation of a free radical (A) by hydrogen abstraction from the cyclohexenyl group. Hyperfine coupling tensors were determined for coupling of the unpaired electron to four protons. Visible light of wavelengths near 450 nm reversibly converts this radical to a second free radical (B) which also has the unpaired electron localized in the cyclohexenyl group. The activation energy for a thermally induced reverse conversion (B ..-->.. A) was determined to be 1.4 eV.

  2. States of high energy density

    International Nuclear Information System (INIS)

    Murray, M.

    1988-02-01

    The transverse energy, E/sub tau/ spectra for O 16 and S 32 incident for various elements at 200 GeVnucleon are shown. The target and projectile dependencies of the data are discussed. The energy density achieved is estimated. For O 16 on Tungsten the multiplicity spectrum is also presented as well as the pseudorapidity spectra as a function of the transverse energy. The multiplicity cross section dσdN as measured in the backward hemisphere (0.9 < /eta/ < 2.9/ is found to be very similar in shape to the transverse energy distribution dσdE/tau/ reflecting the particular geometry of nucleus nucleus nucleus collisions. The dependence on the atomic mass of the target, A/sub tau/ and projectile A/sub p/ is not what one would expect from naive considerations

  3. High density harp for SSCL linac

    International Nuclear Information System (INIS)

    Fritsche, C.T.; Krogh, M.L.; Crist, C.E.

    1993-01-01

    AlliedSignal Inc., Kansas City Division, and the Superconducting Super Collider Laboratory (SSCL) are collaboratively developing a high density harp for the SSCL linac. This harp is designed using hybrid microcircuit (HMC) technology to obtain a higher wire density than previously available. The developed harp contains one hundred twenty-eight 33-micron-diameter carbon wires on 0.38-mm centers. The harp features an onboard broken wire detection circuit. Carbon wire preparation and attachment processes were developed. High density surface mount connectors were located. The status of high density harp development will be presented along with planned future activities

  4. High density harp for SSCL linac

    International Nuclear Information System (INIS)

    Fritsche, C.T.; Krogh, M.L.

    1993-05-01

    AlliedSignal Inc., Kansas City Division, and the Superconducting Super Collider Laboratory (SSCL) are collaboratively developing a high density harp for the SSCL linac. This harp is designed using hybrid microcircuit (HMC) technology to obtain a higher wire density than previously available. The developed harp contains one hundred twenty-eight 33-micron-diameter carbon wires on 0.38-mm centers. The harp features an onboard broken wire detection circuit. Carbon wire preparation and attachment processes were developed. High density surface mount connectors were located. The status of high density harp development will be presented along with planned future activities

  5. High density matter at RHIC

    Indian Academy of Sciences (India)

    are screened, and short range (high momentum) interactions are weak, leading to an ideal gas equation .... I will briefly touch on 'soft physics' ..... thermodynamic concepts to describe multi-particle production has a long history beginning with ...

  6. Effects of gamma radiation induced forced formation of free radicals on the strength of concrete for use in nuclear power plants

    Directory of Open Access Journals (Sweden)

    Burnham Steven

    2017-01-01

    Full Text Available In this paper, we present a summary of preliminary experiments and numerical assessments of the effects of gamma radiation induced formation of free radicals in the curing stage of concrete on its characteristics. Substantial literature reports on the damaging effects of long-term and high-dose gamma and neutron exposure on concrete. However, we show that short-term exposure of concrete to gamma radiation can be beneficial in increasing its compressive strength. The effects of exposing to 630 MBq 137Cs the 56 cubes each made of 125 cm3 concrete during the first seven days of curing are compared to another 56 cubes cured by the conventional process. The average compressive strength of the gamma cured cubes is around 8.500 psi, while conventionally cured cubes show the lower average strength of around 6.700 psi. The microstructure of the gamma and conventionally cured concrete cubes is analyzed using a scanning electron microscope. The radiolysis within the microstructure of the concrete cubes is assessed with computational modeling based on Geant4. The production of free radicals from radiolysis is shown to increase with increasing source strength and increasing the time of exposure to gamma radiation. This research shows in general that curing concrete in gamma radiation field provides observable trends toward its increased strength.

  7. Electronic DC transformer with high power density

    NARCIS (Netherlands)

    Pavlovský, M.

    2006-01-01

    This thesis is concerned with the possibilities of increasing the power density of high-power dc-dc converters with galvanic isolation. Three cornerstones for reaching high power densities are identified as: size reduction of passive components, reduction of losses particularly in active components

  8. New aspects of high energy density plasma

    International Nuclear Information System (INIS)

    Hotta, Eiki

    2005-10-01

    The papers presented at the symposium on 'New aspects of high energy density plasma' held at National Institute for Fusion Science are collected in this proceedings. The papers reflect the present status and recent progress in the experiments and theoretical works on high energy density plasma produced by pulsed power technology. The 13 of the presented papers are indexed individually. (J.P.N.)

  9. High regression rate, high density hybrid fuels, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR program will investigate high energy density novel nanofuels combined with high density binders for use with an N2O oxidizer. Terves has developed...

  10. Magnetization of High Density Hadronic Fluid

    DEFF Research Database (Denmark)

    Bohr, Henrik; Providencia, Constanca; da Providencia, João

    2012-01-01

    In the present paper the magnetization of a high density relativistic fluid of elementary particles is studied. At very high densities, such as may be found in the interior of a neutron star, when the external magnetic field is gradually increased, the energy of the normal phase of the fluid...... in the particle fluid. For nuclear densities above 2 to 3 rho(0), where rho(0) is the equilibrium nuclear density, the resulting magnetic field turns out to be rather huge, of the order of 10(17) Gauss....

  11. High energy density lithium batteries

    CERN Document Server

    Aifantis, Katerina E; Kumar, R Vasant

    2010-01-01

    Cell phones, portable computers and other electronic devices crucially depend on reliable, compact yet powerful batteries. Therefore, intensive research is devoted to improving performance and reducing failure rates. Rechargeable lithium-ion batteries promise significant advancement and high application potential for hybrid vehicles, biomedical devices, and everyday appliances. This monograph provides special focus on the methods and approaches for enhancing the performance of next-generation batteries through the use of nanotechnology. Deeper understanding of the mechanisms and strategies is

  12. Surface modification of lignocellulosic fibers using high-frequency ultrasound

    Science.gov (United States)

    Jayant B. Gadhe; Ram B. Gupta; Thomas Elder

    2005-01-01

    Enzymatic and chemical oxidation of fiber surfaces has been reported in the literature as a method for producing medium density fiberboards without using synthetic adhesives. This work focuses on modifying the surface properties of wood fibers by the generation of free radicals using high-frequency ultrasound. A sonochemical reactor operating at 610 kHz is used to...

  13. UV-generated free radicals (FR) in skin: Their prevention by sunscreens and their induction by self-tanning agents

    Science.gov (United States)

    Jung, K.; Seifert, M.; Herrling, Th.; Fuchs, J.

    2008-05-01

    In the past few years, the cellular effects of ultraviolet (UV) irradiation induced in skin have become increasingly recognized. Indeed, it is now well known that UV irradiation induces structural and cellular changes in all the compartments of skin tissue. The generation of reactive oxygen species (ROS) is the first and immediate consequence of UV exposure and therefore the quantitative determination of free radical reactions in the skin during UV radiation is of primary importance for the understanding of dermatological photodamage. The RSF method (radical sun protection factor) herein presented, based on electron spin resonance spectroscopy (ESR), enables the measurement of free radical reactions in skin biopsies directly during UV radiation. The amount of free radicals varies with UV doses and can be standardized by varying UV irradiance or exposure time. The RSF method allows the determination of the protective effect of UV filters and sunscreens as well as the radical induction capacity of self-tanning agents as dihydroxyacetone (DHA). The reaction of the reducing sugars used in self-tanning products and amino acids in the skin layer (Maillard reaction) leads to the formation of Amadori products that generate free radicals during UV irradiation. Using the RSF method three different self-tanning agents were analyzed and it was found, that in DHA-treated skin more than 180% additional radicals were generated during sun exposure with respect to untreated skin. For this reason the exposure duration in the sun must be shortened when self-tanners are used and photoaging processes are accelerated.

  14. IN VIVO EVIDENCE OF FREE RADICAL FORMATION IN THE RAT LUNG AFTER EXPOSURE TO AN EMISSION SOURCE AIR POLLUTION PARTICLE

    Science.gov (United States)

    Exposure to air pollution particles can be associated with increased human morbidity and mortality. The mechanism(s) of lung injury remains unknown. We tested the hypothesis that lung exposure to oil fly ash (an emission source air pollution particle) causes in vivo free radical ...

  15. Distribution of free radical products among the bases of x-irradiated DNA model systems: an ESR study

    International Nuclear Information System (INIS)

    Spalletta, R.A.

    1984-01-01

    Exposure of solid state DNA to ionizing radiation results in an ESR spectrum that has been attributed to a nonstoichiometric distribution of free radicals among the bases. At low temperatures radical cations appear to be stabilized on the purines while radical anions are stabilized on the pyrimidines. This distribution could arise from at least two different mechanisms. The first, charge transfer, involves the transfer of electrons and/or holes between stacked bases. In the second, saturation asymmetry, the free radical distribution arises from differences in the dose saturation characteristics of individual bases. The present study addresses the relative importance of charge transfer versus saturation asymmetry in the production of these population differences. Radicals formed by dissolving irradiated polycrystalline pyrimidines in aqueous solutions containing NtB or PBN spin traps were analyzed using ESR. The relative importance of the two free radical production and distribution mechanisms was assessed using DNA model systems. Saturation asymmetry plays a significant role in determining the free radical population while charge transfer was unambiguously observed in only one, the complex of dAMP and TMP. The results demonstrate that any quantitative analysis of charge transfer must take saturation asymmetry into account

  16. Toll-Like Receptor-Mediated Free Radical Generation in Clonorchis sinensis Excretory-Secretory Product-Treated Cholangiocarcinoma Cells.

    Science.gov (United States)

    Bahk, Young Yil; Pak, Jhang Ho

    2016-10-01

    Clonorchiasis, caused by direct contact with Clonorchis sinensis worms and their excretory-secretory products (ESPs), is associated with chronic inflammation, malignant changes in bile ducts, and even cholangiocarcinogenesis. Our previous report revealed that intracellular free radicals enzymatically generated by C. sinensis ESPs cause NF-κB-mediated inflammation in human cholangiocarcinoma cells (HuCCT1). Therefore, the present study was conducted to examine the role of upstream Toll-like receptors (TLRs) on the initial host innate immune responses to infection. We found that treatment of HuCCT1 cells with native ESPs induced changes in TLR mRNA levels in a time-dependent manner, concomitant with the generation of free radicals. ESP-mediated free radical generation was markedly attenuated by preincubation of the cells with TLR1-4-neutralizing antibodies, indicating that at least TLR1 through 4 participate in stimulation of the host innate immune responses. These findings indicate that free radicals triggered by ESPs are critically involved in TLR signal transduction. Continuous signaling by this pathway may function in initiating C. sinensis infection-associated inflammation cascades, a detrimental event leading to progression to more severe hepatobiliary diseases.

  17. Direct measurement of free radicals in the brain cortex and the blood serum after nociceptive stimulation in rats

    Czech Academy of Sciences Publication Activity Database

    Rokyta, R.; Stopka, Pavel; Holeček, V.; Křikavá, K.; Pekárková, I.

    2004-01-01

    Roč. 25, č. 4 (2004), s. 252-256 ISSN 0172-780X R&D Projects: GA ČR GA203/01/0944 Institutional research plan: CEZ:AV0Z4032918 Keywords : EPR method * free radicals * pain Subject RIV: CA - Inorganic Chemistry Impact factor: 1.048, year: 2004

  18. Determination of free radical reaction products and metabolites of salicylic acid using capillary electrophoresis and micellar electrokinetic chromatography

    NARCIS (Netherlands)

    Coolen, S.A.J.; Huf, F.A.; Reijenga, J.C.

    1998-01-01

    Hydroxylated radical products of salicylic acid are often used as a relative measurement in free radical research. Several analytical methods exist to determine the amount of 2,3-dihydroxybenzoic acid and 2,5-dihydroxybenzoic acid. In this study we use capillary zone electrophoresis (CZE) and

  19. The role of free-radical processes in the pathogenesis of age-related macular degeneration. Review

    Directory of Open Access Journals (Sweden)

    A. V. Kolesnikov

    2012-01-01

    Full Text Available the modern ideas of the role of free radical processes in the pathogenesis of age-related macular degeneration (AMD are consid- ered. Data of large randomized clinical trials on application of antioxidants for prevention and therapy AMD are provided. Possibility of the differential application of antioxidants depending on the genetic status of patients is discussed.

  20. Proton flux effects and prediction on the free radicals behavior of polyimide in vacuum using EPR measurements in ambient

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Chengyue [Physics Department, Harbin Institute of Technology, Harbin 150001 (China); National Key Lab of Materials Behaviors and Evaluation Technology in Space Environments, Harbin Institute of Technology, Harbin 150001 (China); Wu, Yiyong, E-mail: wuyiyong@hit.edu.cn [National Key Lab of Materials Behaviors and Evaluation Technology in Space Environments, Harbin Institute of Technology, Harbin 150001 (China); Xiao, Jingdong [National Key Lab of Materials Behaviors and Evaluation Technology in Space Environments, Harbin Institute of Technology, Harbin 150001 (China); Yu, Sui [Physics Department, Harbin Institute of Technology, Harbin 150001 (China); Yi, Zhong; Shen, Zicai [Chinese Academy of Sciences, Beijing 100029 (China); Wang, Li [Qian Xuesen Laboratory of Space Technology, Beijing 100029 (China); Wang, Yi [Lanzhou Institute of Physics, CAST, Lanzhou 730000 (China)

    2017-04-15

    Irradiation flux is an important parameter to the material irradiation damage investigation, for space material irradiation damage evaluation and the accelerated ground-based test, the irradiation flux effects cannot be ignored. In this paper, the polyimide was set as the research object, the irradiation flux effect and mechanism are investigated by the means of electron paramagnetic resonance test, and based on the free radical dynamic analysis, the dynamics mode of free radical population in vacumm can be established as a function of irradiation time (or proton irradiation flux). The results show that the free radical anneal process in vacuum follows the exponential mode, and the characteristic time constant τ{sub radical-vacuum} is about 1.9 h. Furthermore, a simplified method is proposed with the investigation of the free radical behavior of the irradiated surface modification polyimide (TiO{sub 2}/PI), and the characteristic time constant τ{sub bulk} is 1.9 h, which is almost the same to the value of τ{sub radical-vacuum}.

  1. In vitro antioxidant and free radical scavenging activity of different parts of Tabebuia pallida growing in Bangladesh.

    Science.gov (United States)

    Rahman, Md Mahbubur; Islam, Md Badrul; Biswas, Mohitosh; Khurshid Alam, A H M

    2015-10-30

    In humans, many diseases are associated with the accumulation of free radicals. Antioxidants can scavenge free radicals and minimize their impact. Therefore, the search for naturally occurring antioxidants of plant origin is imperative. Here, we aimed to investigate the antioxidant and free radical scavenging properties of methanolic extracts from Tabebuia pallida (T. pallida) stem bark (TPSB), root bark (TPRB), leaves (TPL), and flowers (TPF). The antioxidant and free radical scavenging activity were determined by several standard methods using spectrophotomer. Total phenolic and flavonoid contents were estimated using Folin-Ciocalteu reagent and aluminum chloride colorimetric assay methods, respectively. Among the extracts, TPL showed the highest total antioxidant capacity followed by TPRB, TPF, and TPSB. Based on DPPH and hydroxyl radical scavenging activity, TPL showed strong scavenging activity (91.05 ± 1.10 and 62.00 ± 0.57) with IC50 of 9.20 ± 0.28 and 46.00 ± 2.84 μg/mL, respectively when compared with standard BHT (IC50 of 7.00 ± 0.25 μg/mL) and CA (75.00 ± 0.14 μg/mL). These results suggest that TPL had the highest radical scavenging activity among the extractives that closely resembled the standard's. In lipid peroxidation inhibition assay, TPL exhibited the most potent inhibitory activity (83.18 ± 2.12 %) with IC50 of 12.00 ± 2.12 μg/mL, which closely resembled standard CA (IC50 of 10.50 ± 0.28 μg/mL). Also, the reducing capacity on ferrous ion was in the following order: TPL > TPRB > TF > TPSB. The phenolic and flavonoid contents of TPL were higher than other extractives. A positive correlation (p value free radical (DPPH(·) and (·)OH) scavenging efficiencies and lipid peroxidation inhibition activity. Methanolic extract of T. pallida leaf is a potential source of natural antioxidants and serves as an effective free radical scavenger and/or inhibitor. Hence, T. pallida might be a good plant-based pharmaceutical product for several

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

    Science.gov (United States)

    Chu, Wan-Loy; Lim, Yen-Wei; Radhakrishnan, Ammu Kutty; Lim, Phaik-Eem

    2010-09-21

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

  3. Relationship between free radical content in human tooth enamel and radiation dose

    International Nuclear Information System (INIS)

    Zhou Yongzeng; Wang Jiadong; Jia Xiaomei; Wu Ke; Cong Jianbo; Sun Cunpu

    2000-01-01

    Application of ESR technique of tooth enamel have become more and more wide-spread in accidental and retrospective dosimetry. The purpose of this paper is to study relationship between free radical content in tooth enamel and radiation dose. Method Samples of 25 Chinese adult teeth, 25 child permanent teeth and 35 milk teeth were used in the study. All teeth were obtained from patients in the course of dental practice. Tooth enamel was separated from dentine using dental drill and then crushed manually into grains of about 0.5-1.5 mm in diameter. The mass of each sample is 100 mg. Signal intensity of enamel samples was measured by ESR technique (Bruker-ESP300). Parameters used were modulation frequency 50 KHz, modulation amplitude 0.2 mT, time constant 41 ms, scan width 15 mT, microwave power 5 mw, room temperature. Samples of 25 adult teeth, 25 child permanent teeth and 35 milk teeth were divided into 5 dose groups, respectively, and irradiated with 60 Co γ-ray at dose rate of 0.48 Gy/min. Radiation doses of the 5 groups were 0.30, 0.50, 1.00, 3.00 and 5.00 Gy, respectively. After irradiation, each sample was subjected to ESR measurements. There is no significant difference in background signal intensity between male and female samples for both child permanent teeth and milk teeth. And also no significant difference in background signal intensity between child permanent teeth and milk teeth was observed. Results of study on adult teeth indicated that radiation sensitivity of different teeth is fairly uniform. Free radical content in enamel of child permanent teeth and milk teeth increases linearly with increasing of radiation dose, and similar results were obtained for adult teeth. Slope of the dose-response curve for adult teeth is somewhat steeper than that for milk teeth. There exists a linear relation between ESR signals intensity and radiation doses for adult teeth, child permanent and milk teeth. In the case of radiation accident, the dose-response curves

  4. Enzymatic and free radical formation of cis- and trans- epoxyeicosatrienoic acids in vitro and in vivo.

    Science.gov (United States)

    Aliwarga, Theresa; Raccor, Brianne S; Lemaitre, Rozenn N; Sotoodehnia, Nona; Gharib, Sina A; Xu, Libin; Totah, Rheem A

    2017-11-01

    Epoxyeicosatrienoic acids (EETs) are metabolites of arachidonic acid (AA) oxidation that have important cardioprotective and signaling properties. AA is an ω-6 polyunsaturated fatty acid (PUFA) that is prone to autoxidation. Although hydroperoxides and isoprostanes are major autoxidation products of AA, EETs are also formed from the largely overlooked peroxyl radical addition mechanism. While autoxidation yields both cis- and trans-EETs, cytochrome P450 (CYP) epoxygenases have been shown to exclusively catalyze the formation of all regioisomer cis-EETs, on each of the double bonds. In plasma and red blood cell (RBC) membranes, cis- and trans-EETs have been observed, and both have multiple physiological functions. We developed a sensitive ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) assay that separates cis- and trans- isomers of EETs and applied it to determine the relative distribution of cis- vs. trans-EETs in reaction mixtures of AA subjected to free radical oxidation in benzene and liposomes in vitro. We also determined the in vivo distribution of EETs in several tissues, including human and mouse heart, and RBC membranes. We then measured EET levels in heart and RBC of young mice compared to old. Formation of EETs in free radical reactions of AA in benzene and in liposomes exhibited time- and AA concentration-dependent increase and trans-EET levels were higher than cis-EETs under both conditions. In contrast, cis-EET levels were overall higher in biological samples. In general, trans-EETs increased with mouse age more than cis-EETs. We propose a mechanism for the non-enzymatic formation of cis- and trans-EETs involving addition of the peroxyl radical to one of AA's double bonds followed by bond rotation and intramolecular homolytic substitution (S H i). Enzymatic formation of cis-EETs by cytochrome P450 most likely occurs via a one-step concerted mechanism that does not allow bond rotation. The ability to accurately measure

  5. Melatonin against radiation induced free radicals: a study on tissues of Swiss albino mice

    International Nuclear Information System (INIS)

    Bhatia, A.L.; Manda, K.

    2003-01-01

    Full text: Antioxidant enzymes are part of the primary cellular defense against free radicals generated by radiation. Reports on low level chronic administration of melatonin with its antiradiation influence are scanty. Although compelling logic suggests that melatonin may be effective for a variety of disorders, the mode and optimal dose of melatonin is still not clear. Most studies have used doses of supraphysiological blood levels. Present investigation reports that melatonin in relatively lower concentrations increases the mRNA of both superoxide dismutases (SODs) and glutathione peroxidase (GSH-Px) and mediates possibly through receptors. The influence of low dose chronic administration (0.10 mg/Kg body weight/day for 15 days) of melatonin was studied against radiation-induced oxidative stress in 6 to 8 weeks old mice. Just after 24 hours of the last dose in various tissues viz. brain, liver, spleen and kidney were studied for lipid peroxidation, reduced glutathione (GSH), glutathione disulphide (GSSG), glutathione peroxidase (GSH-Px), protein, RNA, DNA and serum phosphatase activity. Radiation induced augmentation in the level of lipid peroxidation, glutathione disulphide (GSSG) and acid phosphatase was significantly ameliorated by pre-irradiation treatment with melatonin. Radiation induced depletion in the level of reduced glutathione (GSH), glutathione peroxidase (GSH-Px) and alkaline phosphatase is significantly averted by melatonin administration. Regression analysis of survival data yielded LD50/30 as 7.16 Gy and 11Gy for control (irradiation alone) and experimental (melatonin + irradiation), respectively. Animals produced a dose reduction factor (DRF) as 1.53. Radiation induced deficit in the body and organ weight was also significantly thwarted in the melatonin pre-treated mice. Results indicate the antioxidative properties of melatonin against the gamma radiation. The findings support the results showing melatonin as a free radical scavenger, and

  6. Synthesis of fused azole-piperidionoses: A free radical cyclization approach

    Energy Technology Data Exchange (ETDEWEB)

    Marco-Contelles, Jose; Alhambra Jimenez, Carolina [Instituto de Quimica Organica General (CSIC), Madrid (Spain)

    1999-08-01

    A new strategy has been reported for the synthesis of fused azole-piperidinoses featuring and unprecedented and very efficient 6-exo-trig free radical cyclization onto heterocyclic sugar templates. These compounds are key intermediates for the synthesis of known or analogues of azole-glycosidase inhibitors. In this communication we describe our recent and successful results on the synthesis of fused triazole-piperidinoses. Radical precursors have been prepared by standard methodologies from 1, 2:5, 6-bis-O-isopropylidene-{alpha}-D-glucofuranose (4) via triazoles linked at C3 with {beta}-orientation, readily obtained by 1, 3-dipolar cycloaddition of azide 5 with diethyl acetylenedicarboxylate or methyl propiolate, and by S{sub N}2 displacement of the tosylate at C3 with 1, 2, 4-triazole in compound 20. The key 6-exp-trig free radical cyclizations proceeded in the usual conditions [tributyltin hydride or tris(trimethylsily)silane, AIBN, toluene] yielding the azaannulated sugars 9, 11, 19 and 23 in good or excellent yields. A mechanism for these cyclizations has been proposed. [Spanish] Se ha informado una nueva estrategia para la sintesis azol-piperidinosas fusionadas mediante una ciclizacion 6-exo-trig muy eficiente y sin precedentes, sobre plantillas de azucares heterociclicos. Estos compuestos son intermediarios claves para la sintesis de inhibidores de azol-glicosidasa conocidos analogos de ellos. En esta comunicacion describimos nuestros resultados recientes y exitosos sobre la sintesis de triazol-piperidinosas. Los precursores de radicales fueron preparados por la metodologia usual a partir de 1, 2:5, 6-bis-O-isopropiliden-{alpha}-D-glucofuranosa (4) via triazoles unidos en C3, con orientacion {beta}, los cuales se obtienen facilmente por cicloadicion 1, 3-dipolar de la azida 5 con acetilendicarboxilato de dietilo o propiolato de metilo y por desplazamiento S{sub N}2 del tosilato en C3 con 1, 2, 4-triazol en el compuesto 20. Las ciclizaciones 6-exo

  7. Evaluation of free radical scavenging and radioprotective efficacy of Aloe vera extract

    International Nuclear Information System (INIS)

    Chakrawarti, Aruna; Purohit, R.K.; Agarwal, Manisha; Ranga, Anita; Saran, Leena

    2012-01-01

    Radiation induced damage and lethality to the normal tissues can be partially reduced by the use of radio-protectors that lower down the damaging effects of radiation. In the present study radio-protective effect of Aloe vera extract which is rich in vitamins. It is basically cellular regenerator and therefore acts, with very positive results in many conditions. It is reported to have antioxidant, anti carcinogenic, antimicrobial and immunity stimulants properties. For the present experiment, healthy Swiss albino mice (6-8 weeks old) were selected and maintained under standard conditions of temperature and light. Aloe vera juice was fed orally at the dose rate of 0.01 m1/animal/day. The animals were divided into seven groups according to the treatment given to them i.e. given cadmium chloride solution as drinking water (group-II) or exposed to 5.0 Gy gamma radiations (group-III) or combined treatment of radiation and cadmium chloride (group-IV). The alterations in the biochemical parameters of all these group were compared with that of sham irradiated animals (group-I). The animals of experimental groups were given Aloe vera seven days prior to radiation or cadmium chloride treatment (group-V, VI and VII) respectively. All biochemical parameters of the control groups were compared with the respective experimental groups. An increase in the value of total proteins, glycogen, acid and alkaline phosphatase activity and RNA was observed up to day-14 in the non drug treated group and day-7 in the Aloe vera groups. Thereafter value declined up to day-28 without reaching to the normal. Whereas the value of cholesterol and DNA showed a decreasing trend up to day-14 in non drug treated groups and day-7 in Aloe vera treated groups. Thus it showed that cadmium and radiation produced toxic effect on kidney and Aloe vera minimize these effects. Protection offered by Aloe vera may be due to the scavenging or oxidizing free radicals. Thus it can be concluded that Aloe vera may

  8. Some recent efforts toward high density implosions

    International Nuclear Information System (INIS)

    McClellan, G.E.

    1980-01-01

    Some recent Livermore efforts towards achieving high-density implosions are presented. The implosion dynamics necessary to compress DT fuel to 10 to 100 times liquid density are discussed. Methods of diagnosing the maximum DT density for a specific design are presented along with results to date. The dynamics of the double-shelled target with an exploding outer shell are described, and some preliminary experimental results are presented

  9. Direct evidence of iNOS-mediated in vivo free radical production and protein oxidation in acetone-induced ketosis

    Science.gov (United States)

    Stadler, Krisztian; Bonini, Marcelo G.; Dallas, Shannon; Duma, Danielle; Mason, Ronald P.; Kadiiska, Maria B.

    2008-01-01

    Diabetic patients frequently encounter ketosis that is characterized by the breakdown of lipids with the consequent accumulation of ketone bodies. Several studies have demonstrated that reactive species are likely to induce tissue damage in diabetes, but the role of the ketone bodies in the process has not been fully investigated. In this study, electron paramagnetic resonance (EPR) spectroscopy combined with novel spin-trapping and immunological techniques has been used to investigate in vivo free radical formation in a murine model of acetone-induced ketosis. A six-line EPR spectrum consistent with the α-(4-pyridyl-1-oxide)-N-t-butylnitrone radical adduct of a carbon-centered lipid-derived radical was detected in the liver extracts. To investigate the possible enzymatic source of these radicals, inducible nitric oxide synthase (iNOS) and NADPH oxidase knockout mice were used. Free radical production was unchanged in the NADPH oxidase knockout but much decreased in the iNOS knockout mice, suggesting a role for iNOS in free radical production. Longer-term exposure to acetone revealed iNOS overexpression in the liver together with protein radical formation, which was detected by confocal microscopy and a novel immunospin-trapping method. Immunohistochemical analysis revealed enhanced lipid peroxidation and protein oxidation as a consequence of persistent free radical generation after 21 days of acetone treatment in control and NADPH oxidase knockout but not in iNOS knockout mice. Taken together, our data demonstrate that acetone administration, a model of ketosis, can lead to protein oxidation and lipid peroxidation through a free radical-dependent mechanism driven mainly by iNOS overexpression. PMID:18559982

  10. Kombucha Tea Ameliorates Trichloroethylene Induced Hepatic Damages in Rats via Inhibition of Oxidative Stress and Free Radicals Induction

    International Nuclear Information System (INIS)

    Gharib, O.A.; Gharib, M.A.

    2008-01-01

    Kombucha Tea (KT) is reported to exhibit a wide variety of biological effects, including antioxidant. Evidence shows the important role of oxidative stress in the hepatic damage. The aim of this study is to investigate the possible protective effects of oral administration of KT in rats with trichloroethylene (TCE)-induced damage for ten consecutive days. Hepatic damage was evaluated by measuring total free radicals levels, biochemical and histological examinations. Serum gamma glutamyl transferase (GGT) activity (the hepatic damage marker), total protein, albumin and globulin as well as malonaldehyde (MDA), glutathione (GSH) content, nitric oxide (NO) concentration were evaluated in liver tissue homogenates. Total free radicals concentration in blood was examined by electron spin resonance (ESR). Total protein, DNA concentration, cell number and cell size in liver tissues were also examined. The rats orally administrated with TCE for ten days indicates hepatic damage changes, an increase in blood total free radicals concentration was observed, serum GGT activity, liver MDA, NO levels, total protein and decreased GSH content, DNA concentration and cell number. This accompanied with an increase in cell size of liver tissues, whereas KT reversed these effects. Furthermore, KT inhibits the concentration of total free radicals in blood and decreasing the increment of MDA and NO concentration. Histological studies reveal partial healing in those rats treated by KT after oral administration with TCE. The present results suggest that KT ameliorates TCE induced hepatic damage in rats probably due to its content of glucuronic, acetic acid and B vitamins via inhibition of oxidative stress and total free radicals

  11. Persistent free radicals, heavy metals and PAHs generated in particulate soot emissions and residue ash from controlled combustion of common types of plastic

    International Nuclear Information System (INIS)

    Valavanidis, Athanasios; Iliopoulos, Nikiforos; Gotsis, George; Fiotakis, Konstantinos

    2008-01-01

    The production and use of polymeric materials worldwide has reached levels of 150 million tonnes per year, and the majority of plastic materials are discarded in waste landfills where are burned generating toxic emissions. In the present study we conducted laboratory experiments for batch combustion/burning of commercial polymeric materials, simulating conditions of open fire combustion, with the purpose to analyze their emissions for chemical characteristics of toxicological importance. We used common types of plastic materials: poly(vinyl chloride) (PVC), low and high density poly(ethylene) (LDPE, HDPE), poly(styrene) (PS), poly(propylene) (PP) and poly(ethylene terephthalate) (PET). Samples of particulate smoke (soot) collected on filters and residue solid ash produced by controlled burning conditions at 600-750 deg. C are used for analysis. Emissions of particulate matter, persistent free radicals embedded in the carbonaceous polymeric matrix, heavy metals, other elements and PAHs were determined in both types of samples. Results showed that all plastics burned easily generating charred residue solid ash and black airborne particulate smoke. Persistent carbon- and oxygen-centered radicals, known for their toxic effects in inhalable airborne particles, were detected in both particulate smoke emissions and residue solid ash. Concentrations of heavy metals and other elements (determined by Inductively Coupled Plasma Emission Spectrometry, ICP, method) were measured in the airborne soot and residue ash. Toxic heavy metals, such as Pb, Zn, Cr, Ni, and Cd were relatively at were found at low concentrations. High concentrations were found for some lithophilic elements, such as Na, Ca, Mg, Si and Al in particulate soot and residue solid ash. Measurements of PAHs showed that low molecular weight PAHs were at higher concentrations in the airborne particulate soot than in the residue solid ash for all types of plastic. Higher-ringed PAHs were detected at higher

  12. Persistent free radicals, heavy metals and PAHs generated in particulate soot emissions and residue ash from controlled combustion of common types of plastic.

    Science.gov (United States)

    Valavanidis, Athanasios; Iliopoulos, Nikiforos; Gotsis, George; Fiotakis, Konstantinos

    2008-08-15

    The production and use of polymeric materials worldwide has reached levels of 150 million tonnes per year, and the majority of plastic materials are discarded in waste landfills where are burned generating toxic emissions. In the present study we conducted laboratory experiments for batch combustion/burning of commercial polymeric materials, simulating conditions of open fire combustion, with the purpose to analyze their emissions for chemical characteristics of toxicological importance. We used common types of plastic materials: poly(vinyl chloride) (PVC), low and high density poly(ethylene) (LDPE, HDPE), poly(styrene) (PS), poly(propylene) (PP) and poly(ethylene terephthalate) (PET). Samples of particulate smoke (soot) collected on filters and residue solid ash produced by controlled burning conditions at 600-750 degrees C are used for analysis. Emissions of particulate matter, persistent free radicals embedded in the carbonaceous polymeric matrix, heavy metals, other elements and PAHs were determined in both types of samples. Results showed that all plastics burned easily generating charred residue solid ash and black airborne particulate smoke. Persistent carbon- and oxygen-centered radicals, known for their toxic effects in inhalable airborne particles, were detected in both particulate smoke emissions and residue solid ash. Concentrations of heavy metals and other elements (determined by Inductively Coupled Plasma Emission Spectrometry, ICP, method) were measured in the airborne soot and residue ash. Toxic heavy metals, such as Pb, Zn, Cr, Ni, and Cd were relatively at were found at low concentrations. High concentrations were found for some lithophilic elements, such as Na, Ca, Mg, Si and Al in particulate soot and residue solid ash. Measurements of PAHs showed that low molecular weight PAHs were at higher concentrations in the airborne particulate soot than in the residue solid ash for all types of plastic. Higher-ringed PAHs were detected at higher

  13. Functionalized graphene quantum dots loaded with free radicals combined with liquid chromatography and tandem mass spectrometry to screen radical scavenging natural antioxidants from Licorice and Scutellariae.

    Science.gov (United States)

    Wang, Guoying; Niu, XiuLi; Shi, Gaofeng; Chen, Xuefu; Yao, Ruixing; Chen, Fuwen

    2014-12-01

    A novel screening method was developed for the detection and identification of radical scavenging natural antioxidants based on a free radical reaction combined with liquid chromatography with tandem mass spectrometry. Functionalized graphene quantum dots were prepared for loading free radicals in the complex screening system. The detection was performed with and without a preliminary exposure of the samples to specific free radicals on the functionalized graphene quantum dots, which can facilitate charge transfer between free radicals and antioxidants. The difference in chromatographic peak areas was used to identify potential antioxidants. This is a novel approach to simultaneously evaluate the antioxidant power of a component versus a free radical, and to identify it in a vegetal matrix. The structures of the antioxidants in the samples were identified using tandem mass spectrometry and comparison with standards. Fourteen compounds were found to possess potential antioxidant activity, and their free radical scavenging capacities were investigated. The order of scavenging capacity of 14 compounds was compared according to their free radical scavenging rate. 4',5,6,7-Tetrahydroxyflavone (radical scavenging rate: 0.05253 mL mg(-1) s(-1) ) showed the strongest capability for scavenging free radicals. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Comparison of ChemicalComposition and Free Radical Scavenging Ability of Glycosidically Bound andFree Volatiles from Bosnian Pine (Pinus heldreichii Christ. var. leucodermis

    Directory of Open Access Journals (Sweden)

    Mladen Milos

    2007-03-01

    Full Text Available The results obtained show that Bosnian pine is richin glycosidically bound volatile compounds with strong free radical scavengingproperties. Since volatiles can be released from nonvolatile glycosideprecursors, these compounds can be considered as a hidden potential source ofantioxidant substances and may contribute to the total free radical scavengingability of Bosnian pine.

  15. Crosslinking of fibrinogen and fibronectin by free radicals : A possible initial step in adhesion formation in osteoarthritis of the temporomandibular joint

    NARCIS (Netherlands)

    Dijkgraaf, LC; Zardeneta, G; Cordewener, FW; Liem, RSB; Schmitz, JP; de Bont, LGM; Milam, SB

    Purpose: Adhesion formation in osteoarthritis (OA) of the temporomandibular joint (TMJ) typically results in a sustained limitation of joint movement. We propose the hypothesis that free-radical-mediated crosslinking of proteins underlies this adhesion formation in affected joints. Free radicals may

  16. Correlation of the radioprotective effect of the methyl gallate on the ruptures induction in DNA and it effect in the capture of free radicals

    International Nuclear Information System (INIS)

    Morales R, P.; Cabral P, A.; Cruz V, V.L.; Gonzalez B, F.; Zarco M, A.

    2007-01-01

    It is shown in alive, the capacity of the methyl gallate to reduce the induced ruptures in the DNA for γ radiation. As well as to capture free radicals in a system in vitro. This suggests that the methyl gallate can be a radioprotector that acts capturing free radicals. (Author)

  17. Effects of oxygen radical scavengers on the inactivation of SS phi X174 DNA by the semi-quinone free radical of the antitumor agent etoposide

    NARCIS (Netherlands)

    van Maanen, M.J.; Mans, D.R.A.; Lafleur, M.V.M.; Van Schaik, M A; de Vries, J; Vermeulen, N P; Retèl, J.; Lankelma, J

    1990-01-01

    We have studied the effects of oxygen radical scavengers on the inactivation of ss phi X174 DNA by the semi-quinone free radical of the antitumor agent etoposide (VP 16-213), which was generated from the ortho-quinone of etoposide at pH greater than or equal to 7.4. A semi-quinone free radical of

  18. Low dose radiation induced hormesis and its mechanism of free radicals

    International Nuclear Information System (INIS)

    Zhang Liyuan; Huo Hongmei; Zhang Yusong; Zhao Peifeng; Li Wei; Jiang Jiagui

    2008-01-01

    Objective: To investigate whether the supernatant (the stimulating fluid) centrifuged from myeloid cells suspension after low dose radiation in vitro can produce hormesis on the normal or radiation damage cells. The mechanism of free radical was probed. Methods: Mouse myeloid cell suspension was irradiated respectively by 0, 2 and 5 Gy, and cultured in vitro. MTT method was used to measure the reproductive activity of cells. Meanwhile, Cytochrome C reduction method was used to determine the concentration of O 2 - . Lastly, the concentration of O 2 - was decreased or increased by adding DPI or PMA, and the effect of such changes on 'the stimulating fluid' was observed. Results: Co-cultured with 'the stimulating fluid', the reproductive activity of the myeloid cells after large dose radiation or the normal myeloid cells were enhanced. Decreasing the concentration of O 2 - ; may degrade the proliferation of the cells after radiation damage; while increasing it may lead to the opposite result. Conclusions: The stimulating fluid can enhance the proliferation of the myeloid cells after radiation damage and also the normal ones. The mechanism of above-mentioned phenomena might be related with the changes of O 2 - concentration. (authors)

  19. Environmentally Persistent Free Radical (EPFRs) - Ambient Air Particulates, Soils and Fate of Some Pollutants

    Science.gov (United States)

    Lomnicki, S. M.

    2017-12-01

    Environmentally Persistent Free Radicals (EPFRs) are relatively recently discovered species that are present on ambient air particulates. Their origin is typically associated with the combustion borne PM, where in the cool zone of the combustion process aromatic precursors react with the metal centers of particulates forming surface-organic complex with radical characteristics. EPFRs have been found to be sufficiently resistant to be emitted from the combustion sources and persist in the ambient air on particulates. Their inhalation has been associated with severe health effects, and potentially are one of the major agents contributing the epidemiological risks of PM exposure. Interestingly, EPFRs can be formed not only at the elevated temperatures but also in ambient conditions, where the contact of precursor molecules with transition metal (but not only) domains can result in adsorbate complexes. In fact, EPFRs have been detected in the contaminated soils, or during the oil spill incidents. It is very likely, that the interaction of some molecules released to the air can result in the formation of EPFRs on the ambient air particulates in atmospheric conditions. These species can be a natural degradation by-products that lead to the formation of oxygenated organics in ambient atmosphere.

  20. Scavenging capacity of strawberry tree (Arbutus unedo L.) leaves on free radicals.

    Science.gov (United States)

    Oliveira, Ivo; Coelho, Valentim; Baltasar, Raquel; Pereira, José Alberto; Baptista, Paula

    2009-07-01

    Despite strawberry tree (Arbutus unedo L.) leaves had a long use in traditional medicine due to its antiseptic, diuretic, astringent and depurative properties, the potential of their antioxidant activity are still lacking. Our study goals to assess the antioxidant and free radical scavenging potential of water, ethanol, methanol and diethyl ether extracts of A. unedo leaves. Total phenols content was achieved spectrophotometrically using Folin-Ciocalteau reagent with gallic acid as standard. Antioxidant activity was evaluated using three different methods: reducing power of iron (III)/ferricyanide complex assay, scavenging effect on DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals and scavenging effect on superoxide radicals by using the PMS-NADH-nitroblue tetrazolium system. Ethanol extracts of A. unedo leaves were the highest in reducing power (IC(50) 232.7 microg/mL) and DPPH scavenging effect (IC(50) 63.2 microg/mL) followed by water extracts (with IC(50) of 287.7 and 73.7 microg/mL, respectively); whereas diethyl ether extracts were the lowest. In the scavenging on superoxide radical assay, methanol extracts obtained the best results (IC(50) 6.9 microg/mL). For all the methods tested the antioxidant activity was concentration dependent. In accordance with antioxidant activity, highest total phenols content were found in ethanol, followed by water, methanol and diethyl ether extract. The results indicated that A. unedo leaves are a potential source of natural antioxidants.