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2009
Ciric-Marjanovic, Gordana; Dragičević, Ljiljana; Milojević, Maja; Mojović, Miloš; Mentus, Slavko; Dojčinović, Biljana; Marjanović, Budimir; Stejskal, Jaroslav
Synthesis and characterization of self-assembled polyaniline nanotubes/silica nanocomposites Journal Article
In: Journal of Physical Chemistry B, vol. 113, no. 20, pp. 7116 – 7127, 2009.
Abstract | Links | BibTeX | Tags:
@article{Ciric-Marjanovic20097116,
title = {Synthesis and characterization of self-assembled polyaniline nanotubes/silica nanocomposites},
author = {Gordana Ciric-Marjanovic and Ljiljana Dragičević and Maja Milojević and Miloš Mojović and Slavko Mentus and Biljana Dojčinović and Budimir Marjanović and Jaroslav Stejskal},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67650065013&doi=10.1021%2fjp900096b&partnerID=40&md5=cda45850184db3f9f2c87f17aff96fee},
doi = {10.1021/jp900096b},
year = {2009},
date = {2009-01-01},
journal = {Journal of Physical Chemistry B},
volume = {113},
number = {20},
pages = {7116 – 7127},
abstract = {Self-assembled semiconducting, paramagnetic polyaniline nanotubes have been synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in aqueous medium in the presence of colloidal silica particles of an average diameter ∼12 nm, without added acid. The electrical conductivity of polyaniline nanotubes/silica nanocomposites is in the range (3.3-4.0) × 10-3 S cm-1. The presence of paramagnetic polaronic emeraldine salt form of polyaniline and phenazine units in nanocomposites was proved by FTIR, Raman, and EPR spectroscopies. The influence of the initial silica/aniline weight ratio on the morphology of polyaniline/silica nanocomposites was studied by scanning and transmission electron microscopies. Nano-composites synthesized by using the initial weight ratio silica/aniline ≤0.2 contain polyaniline nanotubes which have a typical outer diameter of 100-250 nm and an inner diameter of 10-80 nm, and nanorods with a diameter of 60-100 nm, accompanied with polyaniline/silica nanogranules, while the nanocomposite synthesized at weight ratio silica/aniline ∼2 contains polyaniline/silica nanogranules with an average diameter of 35-70 nm. The evolution of molecular and supramolecular structure of polyaniline in the presence of colloidal silica is discussed. © 2009 American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Self-assembled semiconducting, paramagnetic polyaniline nanotubes have been synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in aqueous medium in the presence of colloidal silica particles of an average diameter ∼12 nm, without added acid. The electrical conductivity of polyaniline nanotubes/silica nanocomposites is in the range (3.3-4.0) × 10-3 S cm-1. The presence of paramagnetic polaronic emeraldine salt form of polyaniline and phenazine units in nanocomposites was proved by FTIR, Raman, and EPR spectroscopies. The influence of the initial silica/aniline weight ratio on the morphology of polyaniline/silica nanocomposites was studied by scanning and transmission electron microscopies. Nano-composites synthesized by using the initial weight ratio silica/aniline ≤0.2 contain polyaniline nanotubes which have a typical outer diameter of 100-250 nm and an inner diameter of 10-80 nm, and nanorods with a diameter of 60-100 nm, accompanied with polyaniline/silica nanogranules, while the nanocomposite synthesized at weight ratio silica/aniline ∼2 contains polyaniline/silica nanogranules with an average diameter of 35-70 nm. The evolution of molecular and supramolecular structure of polyaniline in the presence of colloidal silica is discussed. © 2009 American Chemical Society.
Ciric-Marjanovic, Gordana; Dondur, Vera; Milojević, Maja; Mojović, Miloš; Mentus, Slavko; Radulović, Aleksandra; Vuković, Zorica; Stejskal, Jaroslav
Synthesis and characterization of conducting self-assembled polyaniline nanotubes/zeolite nanocomposite Journal Article
In: Langmuir, vol. 25, no. 5, pp. 3122 – 3131, 2009.
Abstract | Links | BibTeX | Tags:
@article{Ciric-Marjanovic20093122,
title = {Synthesis and characterization of conducting self-assembled polyaniline nanotubes/zeolite nanocomposite},
author = {Gordana Ciric-Marjanovic and Vera Dondur and Maja Milojević and Miloš Mojović and Slavko Mentus and Aleksandra Radulović and Zorica Vuković and Jaroslav Stejskal},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-65249102675&doi=10.1021%2fla8030396&partnerID=40&md5=81eec5ed391dfe3aac3e6feadb991f4e},
doi = {10.1021/la8030396},
year = {2009},
date = {2009-01-01},
journal = {Langmuir},
volume = {25},
number = {5},
pages = {3122 – 3131},
abstract = {Self-assembled conducting, paramagnetic polyaniline nanotubes have been synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in aqueous medium in the presence of zeolite HZSM-5, without added acid. The influence of initial zeolite/aniline weight ratio on the conductivity, molecular and supramolecular structure, paramagnetic characteristics, thermal stability, and specific surface area of poly aniline/zeolite composites was studied. The conducting (∼10-2S cm-1), semiconducting (3 × 10-5 S cm-1), and nonconducting (5 × 10-9 S cm-1) composites are produced using the zeolite/aniline weight ratios 1, 5, and 10, respectively. The coexistence of polyaniline nanotubes, which have a typical outer diameter of 70-170 nm and an inner diameter of 5-50 nm, accompanied by nanorods with a diameter of 60-100 nm and polyaniline/zeolite mesoporous aggregates, distinct from the morphology of mieroporous zeolite HZSM-5, was proved in the conducting nanocomposite by scanning and transmission electron microscopies. FTIR spectroscopy confirmed the presence of polyaniline in the form of conducting emeraldine salt and suggested significant interaction of polyaniline with zeolite. The evolution of molecular and supramolecular structure of polyaniline in the presence of zeolite was discussed. © Copyright 2009 American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Self-assembled conducting, paramagnetic polyaniline nanotubes have been synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in aqueous medium in the presence of zeolite HZSM-5, without added acid. The influence of initial zeolite/aniline weight ratio on the conductivity, molecular and supramolecular structure, paramagnetic characteristics, thermal stability, and specific surface area of poly aniline/zeolite composites was studied. The conducting (∼10-2S cm-1), semiconducting (3 × 10-5 S cm-1), and nonconducting (5 × 10-9 S cm-1) composites are produced using the zeolite/aniline weight ratios 1, 5, and 10, respectively. The coexistence of polyaniline nanotubes, which have a typical outer diameter of 70-170 nm and an inner diameter of 5-50 nm, accompanied by nanorods with a diameter of 60-100 nm and polyaniline/zeolite mesoporous aggregates, distinct from the morphology of mieroporous zeolite HZSM-5, was proved in the conducting nanocomposite by scanning and transmission electron microscopies. FTIR spectroscopy confirmed the presence of polyaniline in the form of conducting emeraldine salt and suggested significant interaction of polyaniline with zeolite. The evolution of molecular and supramolecular structure of polyaniline in the presence of zeolite was discussed. © Copyright 2009 American Chemical Society.
Kukavica, Biljana; Mojović, Miloš; Vučinić, Željko; Maksimović, Vuk; Takahama, Umeo; Jovanović, Sonja Veljović
In: Plant and Cell Physiology, vol. 50, no. 2, pp. 304 – 317, 2009.
Abstract | Links | BibTeX | Tags:
@article{Kukavica2009304,
title = {Generation of hydroxyl radical in isolated pea root cell wall, and the role of cell wall-bound peroxidase, Mn-SOD and phenolics in their production},
author = {Biljana Kukavica and Miloš Mojović and Željko Vučinić and Vuk Maksimović and Umeo Takahama and Sonja Veljović Jovanović},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-60149094200&doi=10.1093%2fpcp%2fpcn199&partnerID=40&md5=3a1745eef0e87e4a70c9a99913b2002f},
doi = {10.1093/pcp/pcn199},
year = {2009},
date = {2009-01-01},
journal = {Plant and Cell Physiology},
volume = {50},
number = {2},
pages = {304 – 317},
abstract = {The hydroxyl radical produced in the apoplast has been demonstrated to facilitate cell wall loosening during cell elongation. Cell wall-bound peroxidases (PODs) have been implicated in hydroxyl radical formation. For this mechanism, the apoplast or cell walls should contain the electron donors for (i) H2O2 formation from dioxygen; and (ii) the POD-catalyzed reduction of H2O2 to the hydroxyl radical. The aim of the work was to identify the electron donors in these reactions. In this report, hydroxyl radical (·OH) generation in the cell wall isolated from pea roots was detected in the absence of any exogenous reductants, suggesting that the plant cell wall possesses the capacity to generate ·OH in situ. Distinct POD and Mn-superoxide dismutase (Mn-SOD) isoforms different from other cellular isoforms were shown by native gel electrophoresis to be preferably bound to the cell walls. Electron paramagnetic resonance (EPR) spectroscopy of cell wall isolates containing the spin-trapping reagent, 5-diethoxyphosphoryl-5- methyl-1-pyrroline-N-oxide (DEPMPO), was used for detection of and differentiation between ·OH and the superoxide radical (O 2-·). The data obtained using POD inhibitors confirmed that tightly bound cell wall PODs are involved in DEPMPO/OH adduct formation. A decrease in DEPMPO/OH adduct formation in the presence of H 2O2 scavengers demonstrated that this hydroxyl radical was derived from H2O2. During the generation of ·OH, the concentration of quinhydrone structures (as detected by EPR spectroscopy) increased, suggesting that the H2O2 required for the formation of ·OH in isolated cell walls is produced during the reduction of O2 by hydroxycinnamic acids. Cell wall isolates in which the proteins have been denaturated (including the endogenous POD and SOD) did not produce ·OH. Addition of exogenous H2O2 again induced the production of ·OH, and these were shown to originate from the Fenton reaction with tightly bound metal ions. However, the appearance of the DEPMPO/OOH adduct could also be observed, due to the production of O 2-· when endogenous SOD has been inactivated. Also, O2-· was converted to ·OH in an in vitro horseradish peroxidase (HRP)/H2O2 system to which exogenous SOD has been added. Taken together with the discovery of the cell wall-bound Mn-SOD isoform, these results support the role of such a cell wall-bound SOD in the formation of ·OH jointly with the cell wall-bound POD. According to the above findings, it seems that the hydroxycinnamic acids from the cell wall, acting as reductants, contribute to the formation of H 2O2 in the presence of O2 in an autocatalytic manner, and that POD and Mn-SOD coupled together generate ·OH from such H2O2. © The Author 2008. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The hydroxyl radical produced in the apoplast has been demonstrated to facilitate cell wall loosening during cell elongation. Cell wall-bound peroxidases (PODs) have been implicated in hydroxyl radical formation. For this mechanism, the apoplast or cell walls should contain the electron donors for (i) H2O2 formation from dioxygen; and (ii) the POD-catalyzed reduction of H2O2 to the hydroxyl radical. The aim of the work was to identify the electron donors in these reactions. In this report, hydroxyl radical (·OH) generation in the cell wall isolated from pea roots was detected in the absence of any exogenous reductants, suggesting that the plant cell wall possesses the capacity to generate ·OH in situ. Distinct POD and Mn-superoxide dismutase (Mn-SOD) isoforms different from other cellular isoforms were shown by native gel electrophoresis to be preferably bound to the cell walls. Electron paramagnetic resonance (EPR) spectroscopy of cell wall isolates containing the spin-trapping reagent, 5-diethoxyphosphoryl-5- methyl-1-pyrroline-N-oxide (DEPMPO), was used for detection of and differentiation between ·OH and the superoxide radical (O 2-·). The data obtained using POD inhibitors confirmed that tightly bound cell wall PODs are involved in DEPMPO/OH adduct formation. A decrease in DEPMPO/OH adduct formation in the presence of H 2O2 scavengers demonstrated that this hydroxyl radical was derived from H2O2. During the generation of ·OH, the concentration of quinhydrone structures (as detected by EPR spectroscopy) increased, suggesting that the H2O2 required for the formation of ·OH in isolated cell walls is produced during the reduction of O2 by hydroxycinnamic acids. Cell wall isolates in which the proteins have been denaturated (including the endogenous POD and SOD) did not produce ·OH. Addition of exogenous H2O2 again induced the production of ·OH, and these were shown to originate from the Fenton reaction with tightly bound metal ions. However, the appearance of the DEPMPO/OOH adduct could also be observed, due to the production of O 2-· when endogenous SOD has been inactivated. Also, O2-· was converted to ·OH in an in vitro horseradish peroxidase (HRP)/H2O2 system to which exogenous SOD has been added. Taken together with the discovery of the cell wall-bound Mn-SOD isoform, these results support the role of such a cell wall-bound SOD in the formation of ·OH jointly with the cell wall-bound POD. According to the above findings, it seems that the hydroxycinnamic acids from the cell wall, acting as reductants, contribute to the formation of H 2O2 in the presence of O2 in an autocatalytic manner, and that POD and Mn-SOD coupled together generate ·OH from such H2O2. © The Author 2008. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved.
Spasojević, Ivan; Mojović, Miloš; Blagojević, Duško; Spasić, Snežana D.; Jones, David R.; Nikolić-Kokić, Aleksandra; Spasić, Mihajlo B.
Relevance of the capacity of phosphorylated fructose to scavenge the hydroxyl radical Journal Article
In: Carbohydrate Research, vol. 344, no. 1, pp. 80 – 84, 2009.
Abstract | Links | BibTeX | Tags:
@article{Spasojević200980,
title = {Relevance of the capacity of phosphorylated fructose to scavenge the hydroxyl radical},
author = {Ivan Spasojević and Miloš Mojović and Duško Blagojević and Snežana D. Spasić and David R. Jones and Aleksandra Nikolić-Kokić and Mihajlo B. Spasić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-57749111966&doi=10.1016%2fj.carres.2008.09.025&partnerID=40&md5=efd9e15381559ca758d6e1449d776864},
doi = {10.1016/j.carres.2008.09.025},
year = {2009},
date = {2009-01-01},
journal = {Carbohydrate Research},
volume = {344},
number = {1},
pages = {80 – 84},
abstract = {The hydroxyl radical (radical dotOH) has detrimental biological activity due to its very high reactivity. Our experiments were designed to determine the effects of equimolar concentrations of glucose, fructose and mannitol and three phosphorylated forms of fructose (fructose-1-phosphate (F1P); fructose-6-phosphate (F6P); and fructose-1,6-bis(phosphate) (F16BP)) on radical dotOH radical production via the Fenton reaction. EPR spectroscopy using spin-trap DEPMPO was applied to detect radical production. We found that the percentage inhibition of radical dotOH radical formation decreased in the order F16BP > F1P > F6P > fructose > mannitol = glucose. As ketoses can sequester redox-active iron thus preventing the Fenton reaction, the Haber-Weiss-like system was also employed to generate radical dotOH, so that the effect of iron sequestration could be distinguished from direct radical dotOH radical scavenging. In the latter system, the rank order of radical dotOH scavenging activity was F16BP > F1P > F6P > fructose = mannitol = glucose. Our results clearly demonstrate that intracellular phosphorylated forms of fructose have more scavenging properties than fructose or glucose, leading us to conclude that the acute administration of fructose could overcome the body's reaction to exogenous antioxidants during appropriate therapy in certain pathophysiological conditions related to oxidative stress, such as sepsis, neurodegenerative diseases, atherosclerosis, malignancy, and some complications of pregnancy. © 2008 Elsevier Ltd. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The hydroxyl radical (radical dotOH) has detrimental biological activity due to its very high reactivity. Our experiments were designed to determine the effects of equimolar concentrations of glucose, fructose and mannitol and three phosphorylated forms of fructose (fructose-1-phosphate (F1P); fructose-6-phosphate (F6P); and fructose-1,6-bis(phosphate) (F16BP)) on radical dotOH radical production via the Fenton reaction. EPR spectroscopy using spin-trap DEPMPO was applied to detect radical production. We found that the percentage inhibition of radical dotOH radical formation decreased in the order F16BP > F1P > F6P > fructose > mannitol = glucose. As ketoses can sequester redox-active iron thus preventing the Fenton reaction, the Haber-Weiss-like system was also employed to generate radical dotOH, so that the effect of iron sequestration could be distinguished from direct radical dotOH radical scavenging. In the latter system, the rank order of radical dotOH scavenging activity was F16BP > F1P > F6P > fructose = mannitol = glucose. Our results clearly demonstrate that intracellular phosphorylated forms of fructose have more scavenging properties than fructose or glucose, leading us to conclude that the acute administration of fructose could overcome the body's reaction to exogenous antioxidants during appropriate therapy in certain pathophysiological conditions related to oxidative stress, such as sepsis, neurodegenerative diseases, atherosclerosis, malignancy, and some complications of pregnancy. © 2008 Elsevier Ltd. All rights reserved.
Živković, Jelena; Zeković, Zoran; Mujić, Ibrahim; Signevac, Dejan Gocrossed D; Mojović, Miloš; Mujić, Aida; Spasojević, Ivan
In: Food Biophysics, vol. 4, no. 2, pp. 126 – 133, 2009.
Abstract | Links | BibTeX | Tags:
@article{Živković2009126,
title = {EPR spin-trapping and spin-probing spectroscopy in assessing antioxidant properties: Example on extracts of catkin, leaves, and spiny burs of castanea sativa},
author = {Jelena Živković and Zoran Zeković and Ibrahim Mujić and Dejan Gocrossed D Signevac and Miloš Mojović and Aida Mujić and Ivan Spasojević},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67349213556&doi=10.1007%2fs11483-009-9109-8&partnerID=40&md5=396637db5c47c6c616ea572464c292d4},
doi = {10.1007/s11483-009-9109-8},
year = {2009},
date = {2009-01-01},
journal = {Food Biophysics},
volume = {4},
number = {2},
pages = {126 – 133},
abstract = {Electron paramagnetic resonance (EPR) spin-trapping and spin-probing techniques were applied to determine antioxidant activity of extracts of catkin, leaves, and spiny burs of Castanea sativa against physiologically relevant reactive species-superoxide and hydroxyl radical generated in simple chemical systems and hydrogen peroxide applied on erythrocytes. Efflux of K + was used as a marker of membrane integrity. Chemical composition of extracts was analyzed using HPLC/DAD and LC/MS. Extracts showed high antioxidative capacity against superoxide but lower activity against hydroxyl radical. They protected fluidity and integrity of membranes of erythrocytes exposed to hydrogen peroxide. Levels of derivatives of ellagitannins showed positive correlation with the antioxidative activity of extracts. Therefore, ellagitannins from chestnut extracts could represent easily accessible natural antioxidants and beneficial component of human diet in pathophysiological conditions related to oxidative stress. In conclusion, EPR spectroscopy represents a valuable tool for evaluation of antioxidant activity in both hydrophilic and lipophilic media. © 2009 Springer Science+Business Media, LLC.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Electron paramagnetic resonance (EPR) spin-trapping and spin-probing techniques were applied to determine antioxidant activity of extracts of catkin, leaves, and spiny burs of Castanea sativa against physiologically relevant reactive species-superoxide and hydroxyl radical generated in simple chemical systems and hydrogen peroxide applied on erythrocytes. Efflux of K + was used as a marker of membrane integrity. Chemical composition of extracts was analyzed using HPLC/DAD and LC/MS. Extracts showed high antioxidative capacity against superoxide but lower activity against hydroxyl radical. They protected fluidity and integrity of membranes of erythrocytes exposed to hydrogen peroxide. Levels of derivatives of ellagitannins showed positive correlation with the antioxidative activity of extracts. Therefore, ellagitannins from chestnut extracts could represent easily accessible natural antioxidants and beneficial component of human diet in pathophysiological conditions related to oxidative stress. In conclusion, EPR spectroscopy represents a valuable tool for evaluation of antioxidant activity in both hydrophilic and lipophilic media. © 2009 Springer Science+Business Media, LLC.
Daković, Marko; Mojović, Miloš; Bačić, Goran
EPR study of the production of OH radicals in aqueous solutions of uranium irradiated by ultraviolet light; [Russian Source] Journal Article
In: Journal of the Serbian Chemical Society, vol. 74, no. 6, pp. 651 – 661, 2009.
Abstract | Links | BibTeX | Tags:
@article{Daković2009651,
title = {EPR study of the production of OH radicals in aqueous solutions of uranium irradiated by ultraviolet light; [Russian Source]},
author = {Marko Daković and Miloš Mojović and Goran Bačić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-68949085650&doi=10.2298%2fJSC0906651D&partnerID=40&md5=d74ca1b3fba8dca9bbfd34904aebb7b9},
doi = {10.2298/JSC0906651D},
year = {2009},
date = {2009-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {74},
number = {6},
pages = {651 – 661},
abstract = {The aim of the study was to establish whether hydroxyl radicals (•OH) were produced in UV-irradiated aqueous solutions of uranyl salts. The production of •OH was studied in uranyl acetate and nitrate solutions by an EPR spin trap method over a wide pH range, with variation of the uranium concentrations. The production of •OH in uranyl solutions irradiated with UV was unequivocally demonstrated for the first time using the EPR spin-trapping method. The production of •OH can be connected to speciation of uranium species in aqueous solutions, showing a complex dependence on the solution pH. When compared with the results of radiative de-excitation of excited uranyl (* UO22+) by the quenching of its fluorescence, the present results indicate that the generation of hydroxyl radicals plays a major role in the fluorescence decay of * UO22+. The role of the presence of carbonates and counter ions pertinent to environmental conditions in biological systems on the production of hydroxyl radicals was also assessed in an attempt to reveal the mechanism of * UO22+ de-excitation. Various mechanisms, including •OH production, are inferred but the main point is that the generation of •OH in uranium containing solutions must be considered when assessing uranium toxicity. Copyright CC(2009) SCS.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The aim of the study was to establish whether hydroxyl radicals (•OH) were produced in UV-irradiated aqueous solutions of uranyl salts. The production of •OH was studied in uranyl acetate and nitrate solutions by an EPR spin trap method over a wide pH range, with variation of the uranium concentrations. The production of •OH in uranyl solutions irradiated with UV was unequivocally demonstrated for the first time using the EPR spin-trapping method. The production of •OH can be connected to speciation of uranium species in aqueous solutions, showing a complex dependence on the solution pH. When compared with the results of radiative de-excitation of excited uranyl (* UO22+) by the quenching of its fluorescence, the present results indicate that the generation of hydroxyl radicals plays a major role in the fluorescence decay of * UO22+. The role of the presence of carbonates and counter ions pertinent to environmental conditions in biological systems on the production of hydroxyl radicals was also assessed in an attempt to reveal the mechanism of * UO22+ de-excitation. Various mechanisms, including •OH production, are inferred but the main point is that the generation of •OH in uranium containing solutions must be considered when assessing uranium toxicity. Copyright CC(2009) SCS.
Kojic, Danijela; Spasojevic, Ivan; Mojovic, Miloš; Blagojevic, Duško; Worland, M. Roger; Grubor-Lajsic, Gordana; Spasic, Mihajlo B.
Potential role of hydrogen peroxide and melanin in the cold hardiness of Ostrinia nubilalis (Lepidoptera: Pyralidae) Journal Article
In: European Journal of Entomology, vol. 106, no. 3, pp. 451 – 454, 2009.
Abstract | Links | BibTeX | Tags:
@article{Kojic2009451,
title = {Potential role of hydrogen peroxide and melanin in the cold hardiness of Ostrinia nubilalis (Lepidoptera: Pyralidae)},
author = {Danijela Kojic and Ivan Spasojevic and Miloš Mojovic and Duško Blagojevic and M. Roger Worland and Gordana Grubor-Lajsic and Mihajlo B. Spasic},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-71949101615&doi=10.14411%2feje.2009.056&partnerID=40&md5=b5b45070bc766cdb874fdaa92f016b71},
doi = {10.14411/eje.2009.056},
year = {2009},
date = {2009-01-01},
journal = {European Journal of Entomology},
volume = {106},
number = {3},
pages = {451 – 454},
abstract = {The aim of this study was to investigate the relationship between antioxidant enzymes and reactive oxygen species production in diapausing larvae of the European corn borer, Ostrinia nubilalis (Lepidoptera: Pyralidae) kept at 5°C, -3°C and -16°C for two weeks. The amount of hydrogen peroxide (H2O2), activity of antioxidant enzymes, copper zinc superoxide dismutase (CuZnSOD), manganese superoxide dismutases (MnSOD) and catalase (CAT) in whole body homogenates, as well as the electron paramagnetic resonance (EPR) spectroscopy of this insect's whole body were analysed. A higher level of melanin radical and lower CuZnSOD and CAT activities were found in larvae kept at -3°C than at 5°C and -16°C. At the same temperature (-3°C) an elevated H2O2 concentration was recorded. A possible regulatory role of H2O2 at -3°C, which is the temperature that triggers freezing tolerance, is suggested. © 2003 Institute of Entomology.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The aim of this study was to investigate the relationship between antioxidant enzymes and reactive oxygen species production in diapausing larvae of the European corn borer, Ostrinia nubilalis (Lepidoptera: Pyralidae) kept at 5°C, -3°C and -16°C for two weeks. The amount of hydrogen peroxide (H2O2), activity of antioxidant enzymes, copper zinc superoxide dismutase (CuZnSOD), manganese superoxide dismutases (MnSOD) and catalase (CAT) in whole body homogenates, as well as the electron paramagnetic resonance (EPR) spectroscopy of this insect's whole body were analysed. A higher level of melanin radical and lower CuZnSOD and CAT activities were found in larvae kept at -3°C than at 5°C and -16°C. At the same temperature (-3°C) an elevated H2O2 concentration was recorded. A possible regulatory role of H2O2 at -3°C, which is the temperature that triggers freezing tolerance, is suggested. © 2003 Institute of Entomology.
2008
Bačić, Goran; Spasojević, Ivan; Šećerov, Bojana; Mojović, Miloš
Spin-trapping of oxygen free radicals in chemical and biological systems: New traps, radicals and possibilities Journal Article
In: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, vol. 69, no. 5, pp. 1354 – 1366, 2008.
Abstract | Links | BibTeX | Tags:
@article{Bačić20081354,
title = {Spin-trapping of oxygen free radicals in chemical and biological systems: New traps, radicals and possibilities},
author = {Goran Bačić and Ivan Spasojević and Bojana Šećerov and Miloš Mojović},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-42149158251&doi=10.1016%2fj.saa.2007.09.047&partnerID=40&md5=f41fe03eec3fadb649a427f1029d8d4a},
doi = {10.1016/j.saa.2007.09.047},
year = {2008},
date = {2008-01-01},
journal = {Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy},
volume = {69},
number = {5},
pages = {1354 – 1366},
abstract = {The choice of the spin-trap that is to be applied in any EPR study represents the crossroad between a comprehensive investigation and an "ordinary" quantification of production of radicals. So, the scope of our study was to compare the performance of different spin-traps for qualitative analysis of radical-generating systems, and their ability to recognize previously unnoticed radicals. In addition, we present a brief account of the difficulties involved in the detection of oxygen-centered radicals in chemical and biological systems accompanied by the rationale for using the EPR spin-trapping technique in quantitative studies of such reactive species. Certain technical aspects of EPR experiments related to efficient trapping of free radicals in biochemical systems are also discussed. As an example we present here results obtained using EPR spectroscopy and the spin-trap DEPMPO, which show that the Fenton reaction, as well as various biological systems generate a previously unappreciated hydrogen (radical dotH) atom. © 2007 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The choice of the spin-trap that is to be applied in any EPR study represents the crossroad between a comprehensive investigation and an "ordinary" quantification of production of radicals. So, the scope of our study was to compare the performance of different spin-traps for qualitative analysis of radical-generating systems, and their ability to recognize previously unnoticed radicals. In addition, we present a brief account of the difficulties involved in the detection of oxygen-centered radicals in chemical and biological systems accompanied by the rationale for using the EPR spin-trapping technique in quantitative studies of such reactive species. Certain technical aspects of EPR experiments related to efficient trapping of free radicals in biochemical systems are also discussed. As an example we present here results obtained using EPR spectroscopy and the spin-trap DEPMPO, which show that the Fenton reaction, as well as various biological systems generate a previously unappreciated hydrogen (radical dotH) atom. © 2007 Elsevier B.V. All rights reserved.
Godevac, Dejan; Vujisić, Ljubodrag; Mojović, Miloš; Ignjatović, Aleksandar; Spasojević, Ivan; Vajs, Vlatka
Evaluation of antioxidant capacity of Allium ursinum L. volatile oil and its effect on membrane fluidity Journal Article
In: Food Chemistry, vol. 107, no. 4, pp. 1692 – 1700, 2008.
Abstract | Links | BibTeX | Tags:
@article{Godevac20081692,
title = {Evaluation of antioxidant capacity of Allium ursinum L. volatile oil and its effect on membrane fluidity},
author = {Dejan Godevac and Ljubodrag Vujisić and Miloš Mojović and Aleksandar Ignjatović and Ivan Spasojević and Vlatka Vajs},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-36448978506&doi=10.1016%2fj.foodchem.2007.10.017&partnerID=40&md5=8d3b102026c429cf7918f62d79d34886},
doi = {10.1016/j.foodchem.2007.10.017},
year = {2008},
date = {2008-01-01},
journal = {Food Chemistry},
volume = {107},
number = {4},
pages = {1692 – 1700},
abstract = {A total of 20 components were identified in Allium ursinum volatile oil (AUVO) by GC-MS, and 10 of them are found for the first time in this plant species. The antioxidant capacity of AUVO was examined by β-carotene-linoleic acid bleaching, lipid peroxidation by Fenton reaction, EPR spin-probing assay using stable nitroxide radicals, DPPHradical dot, and ABTSradical dot+ scavenging assays. Reaction mechanism of the volatile oil components with nitroxide radicals, based on IR spectra analysis, is proposed. AUVO demonstrated poor scavenging ability against DPPHradical dot and ABTSradical dot+ comparing to synthetic antioxidants BHT and trolox, while in β-carotene-linoleic acid system AUVO showed an effect comparable to those for BHT. AUVO was also capable to scavenge stable nitroxide radicals such as water-soluble Tempone, and 7-DS and 12-DS, incorporated into the liposome membrane. Finally, AUVO increased membrane fluidity, which could be an important feature for further in vivo investigation of some disorders, such as hypertension and atherosclerosis. © 2007 Elsevier Ltd. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A total of 20 components were identified in Allium ursinum volatile oil (AUVO) by GC-MS, and 10 of them are found for the first time in this plant species. The antioxidant capacity of AUVO was examined by β-carotene-linoleic acid bleaching, lipid peroxidation by Fenton reaction, EPR spin-probing assay using stable nitroxide radicals, DPPHradical dot, and ABTSradical dot+ scavenging assays. Reaction mechanism of the volatile oil components with nitroxide radicals, based on IR spectra analysis, is proposed. AUVO demonstrated poor scavenging ability against DPPHradical dot and ABTSradical dot+ comparing to synthetic antioxidants BHT and trolox, while in β-carotene-linoleic acid system AUVO showed an effect comparable to those for BHT. AUVO was also capable to scavenge stable nitroxide radicals such as water-soluble Tempone, and 7-DS and 12-DS, incorporated into the liposome membrane. Finally, AUVO increased membrane fluidity, which could be an important feature for further in vivo investigation of some disorders, such as hypertension and atherosclerosis. © 2007 Elsevier Ltd. All rights reserved.
Bogdanović, J.; Mojović, M.; Milosavić, N.; Mitrović, A.; Vučinić, Ž.; Spasojević, I.
Role of fructose in the adaptation of plants to cold-induced oxidative stress Journal Article
In: European Biophysics Journal, vol. 37, no. 7, pp. 1241 – 1246, 2008.
Abstract | Links | BibTeX | Tags:
@article{Bogdanović20081241,
title = {Role of fructose in the adaptation of plants to cold-induced oxidative stress},
author = {J. Bogdanović and M. Mojović and N. Milosavić and A. Mitrović and Ž. Vučinić and I. Spasojević},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-50449105987&doi=10.1007%2fs00249-008-0260-9&partnerID=40&md5=025a55921bc130426ef8ff55eaed5332},
doi = {10.1007/s00249-008-0260-9},
year = {2008},
date = {2008-01-01},
journal = {European Biophysics Journal},
volume = {37},
number = {7},
pages = {1241 – 1246},
abstract = {This work presents findings, which indicate important role of fructose, fructose 6-phosphate (F6P), and fructose 1,6-bisphosphate (FBP) in preservation of homeostasis in plants under low temperature. Cold combined with light is known to incite increased generation of superoxide in chloroplasts leading to photoinhibition, but also an increased level of soluble sugars. In the present study, oxidative stress in pea leaves provoked by cold/light regime was asserted by the observed decrease of the level of oxidized form of PSI pigment P700 (P700+). Alongside, the increased antioxidative status and the accumulation of fructose were observed. The antioxidative properties of fructose and its phosphorylated forms were evaluated to appraise their potential protective role in plants exposed to chilling stress. Fructose, and particularly F6P and FBP exhibited high capacities for scavenging superoxide and showed to be involved in antioxidative protection in pea leaves. These results combined with previously established links implicate that the increase in level of fructose sugars through various pathways intercalated into physiological mechanisms of homeostasis represents important non-enzymatic antioxidative defense in plants under cold-related stress. © 2008 EBSA.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This work presents findings, which indicate important role of fructose, fructose 6-phosphate (F6P), and fructose 1,6-bisphosphate (FBP) in preservation of homeostasis in plants under low temperature. Cold combined with light is known to incite increased generation of superoxide in chloroplasts leading to photoinhibition, but also an increased level of soluble sugars. In the present study, oxidative stress in pea leaves provoked by cold/light regime was asserted by the observed decrease of the level of oxidized form of PSI pigment P700 (P700+). Alongside, the increased antioxidative status and the accumulation of fructose were observed. The antioxidative properties of fructose and its phosphorylated forms were evaluated to appraise their potential protective role in plants exposed to chilling stress. Fructose, and particularly F6P and FBP exhibited high capacities for scavenging superoxide and showed to be involved in antioxidative protection in pea leaves. These results combined with previously established links implicate that the increase in level of fructose sugars through various pathways intercalated into physiological mechanisms of homeostasis represents important non-enzymatic antioxidative defense in plants under cold-related stress. © 2008 EBSA.
Filipović, Miloš R.; Duerr, Katharina; Mojović, Miloš; Simeunović, Vladica; Zimmermann, Robert; Niketić, Vesna; Ivanović-Burmazović, Ivana
NO dismutase activity of seven-coordinate manganese(II) pentaazamacrocyclic complexes Journal Article
In: Angewandte Chemie - International Edition, vol. 47, no. 45, pp. 8735 – 8739, 2008.
Abstract | Links | BibTeX | Tags:
@article{Filipović20088735,
title = {NO dismutase activity of seven-coordinate manganese(II) pentaazamacrocyclic complexes},
author = {Miloš R. Filipović and Katharina Duerr and Miloš Mojović and Vladica Simeunović and Robert Zimmermann and Vesna Niketić and Ivana Ivanović-Burmazović},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-55249091126&doi=10.1002%2fanie.200801325&partnerID=40&md5=9ce584f68a0e9cf9f27296e391311168},
doi = {10.1002/anie.200801325},
year = {2008},
date = {2008-01-01},
journal = {Angewandte Chemie - International Edition},
volume = {47},
number = {45},
pages = {8735 – 8739},
abstract = {Redox selectivity? Seven-coordinate manganese(II) pentaazamacrocyclic complexes stimulate NO disproportionation by a novel dismutation mechanism based on the formation of labile metal-nitrosyl adducts and which is associated with the MnII/MnIII redox cycle. The metal-bound NO in these aducts has the character and reactivity of NO- and NO+ species. Ex vivo studies suggest that superoxide dismutase mimics of this kind could interfere with NO-mediated processes in biological milieu. (Chemical Equation Presented) © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Redox selectivity? Seven-coordinate manganese(II) pentaazamacrocyclic complexes stimulate NO disproportionation by a novel dismutation mechanism based on the formation of labile metal-nitrosyl adducts and which is associated with the MnII/MnIII redox cycle. The metal-bound NO in these aducts has the character and reactivity of NO- and NO+ species. Ex vivo studies suggest that superoxide dismutase mimics of this kind could interfere with NO-mediated processes in biological milieu. (Chemical Equation Presented) © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.
2006
Maksimović, Vuk; Mojović, Miloš; Vučinić, Željko
Monosaccharide-H 2 O 2 reactions as a source of glycolate and their stimulation by hydroxyl radicals Journal Article
In: Carbohydrate Research, vol. 341, no. 14, pp. 2360 – 2369, 2006.
Abstract | Links | BibTeX | Tags:
@article{Maksimović20062360,
title = {Monosaccharide-H 2 O 2 reactions as a source of glycolate and their stimulation by hydroxyl radicals},
author = {Vuk Maksimović and Miloš Mojović and Željko Vučinić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33747801093&doi=10.1016%2fj.carres.2006.06.023&partnerID=40&md5=f26dbe11f9acbf8a464e76e446e12a98},
doi = {10.1016/j.carres.2006.06.023},
year = {2006},
date = {2006-01-01},
journal = {Carbohydrate Research},
volume = {341},
number = {14},
pages = {2360 – 2369},
abstract = {An analysis of the H 2 O 2 -induced breakdown and transformation of different keto-monosaccharides at physiological concentrations reveals that glycolate and other short-chained carbohydrates and organic acids are produced. Depletion of monosaccharides and glycolate synthesis occurs at increased rates as the length of the carbohydrate chain is decreased, and is significantly increased in the presence of trace amounts of Fe 2+ ions (10 μM). Rates of monosaccharide depletion (initial concentration of 3 mM) observed were up to 1.55 mmol h -1 in the case of fructose, and 2.59 mmol h -1 in the case of dihydroxyacetone, depending upon pH, H 2 O 2 concentration, temperature and the presence or absence of catalytic amounts of Fe 2+ . Glycolate was produced by dihydroxyacetone cleavage at rates up to 0.45 mmol h -1 in the absence, and up to 1.88 mmol h -1 in the presence of Fe 2+ ions (pH 8). Besides glycolate, other sugars (ribose, glyceraldehyde, glucose), glucitol (sorbitol) and organic acids (formic and 2-oxogluconic acid) were produced in such H 2 O 2 -induced reactions with fructose or dihydroxyacetone. EPR measurements demonstrated the participation of the radical dot OH radical, especially at higher pH. Presence of metal ions at higher pH values, resulting in increased glycolate synthesis, was accompanied by enhanced hydroxyl radical generation. Observed changes in intensity of DEPMPO-OH signals recorded from dihydroxyacetone and fructose reactions demonstrate a strong correlation with changes in glycolate yield, suggesting that radical dot OH radical formation enhances glycolate synthesis. The results presented suggest that different mechanisms are responsible for the cleavage or other reactions (isomerisation, auto- or free-radical-mediated oxidation) of keto-monosaccharides depending of experimental conditions. © 2006 Elsevier Ltd. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
An analysis of the H 2 O 2 -induced breakdown and transformation of different keto-monosaccharides at physiological concentrations reveals that glycolate and other short-chained carbohydrates and organic acids are produced. Depletion of monosaccharides and glycolate synthesis occurs at increased rates as the length of the carbohydrate chain is decreased, and is significantly increased in the presence of trace amounts of Fe 2+ ions (10 μM). Rates of monosaccharide depletion (initial concentration of 3 mM) observed were up to 1.55 mmol h -1 in the case of fructose, and 2.59 mmol h -1 in the case of dihydroxyacetone, depending upon pH, H 2 O 2 concentration, temperature and the presence or absence of catalytic amounts of Fe 2+ . Glycolate was produced by dihydroxyacetone cleavage at rates up to 0.45 mmol h -1 in the absence, and up to 1.88 mmol h -1 in the presence of Fe 2+ ions (pH 8). Besides glycolate, other sugars (ribose, glyceraldehyde, glucose), glucitol (sorbitol) and organic acids (formic and 2-oxogluconic acid) were produced in such H 2 O 2 -induced reactions with fructose or dihydroxyacetone. EPR measurements demonstrated the participation of the radical dot OH radical, especially at higher pH. Presence of metal ions at higher pH values, resulting in increased glycolate synthesis, was accompanied by enhanced hydroxyl radical generation. Observed changes in intensity of DEPMPO-OH signals recorded from dihydroxyacetone and fructose reactions demonstrate a strong correlation with changes in glycolate yield, suggesting that radical dot OH radical formation enhances glycolate synthesis. The results presented suggest that different mechanisms are responsible for the cleavage or other reactions (isomerisation, auto- or free-radical-mediated oxidation) of keto-monosaccharides depending of experimental conditions. © 2006 Elsevier Ltd. All rights reserved.
2005
Veljović-Jovanović, Sonja; Kukavica, Biljana; Cvetić, Tijana; Mojović, Miloš; Vučinić, Željko
Ascorbic acid and the oxidative processes in pea root cell wall isolates: Characterization by fluorescence and EPR spectroscopy Journal Article
In: Annals of the New York Academy of Sciences, vol. 1048, pp. 500 – 504, 2005.
Abstract | Links | BibTeX | Tags:
@article{Veljović-Jovanović2005500,
title = {Ascorbic acid and the oxidative processes in pea root cell wall isolates: Characterization by fluorescence and EPR spectroscopy},
author = {Sonja Veljović-Jovanović and Biljana Kukavica and Tijana Cvetić and Miloš Mojović and Željko Vučinić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-25144470117&doi=10.1196%2fannals.1342.076&partnerID=40&md5=0d832399737d944722017d3ab82e5494},
doi = {10.1196/annals.1342.076},
year = {2005},
date = {2005-01-01},
journal = {Annals of the New York Academy of Sciences},
volume = {1048},
pages = {500 – 504},
abstract = {A comparative fluorescence and oxygen radical-sensitive spin trap EPR spectroscopic study of isolated cell walls (with proteins or deproteinated), in the presence and absence of ascorbate and H2O2 is presented. Fluorescence spectra indicate the presence of at least two fluorophores, one degraded and the other synthesized after reduction or oxidation, indicating phenol di/polymerization. DEPMPO spin trap measurements show that isolated cell walls are capable of oxygen-dependent hydroxyl radical generation in the absence of NADH or other reductants, ascorbate addition, or deproteination of the cell wall abolishing the signal due to hydroxyl radicals. © 2005 New York Academy of Sciences.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A comparative fluorescence and oxygen radical-sensitive spin trap EPR spectroscopic study of isolated cell walls (with proteins or deproteinated), in the presence and absence of ascorbate and H2O2 is presented. Fluorescence spectra indicate the presence of at least two fluorophores, one degraded and the other synthesized after reduction or oxidation, indicating phenol di/polymerization. DEPMPO spin trap measurements show that isolated cell walls are capable of oxygen-dependent hydroxyl radical generation in the absence of NADH or other reductants, ascorbate addition, or deproteination of the cell wall abolishing the signal due to hydroxyl radicals. © 2005 New York Academy of Sciences.
Maksimović, Vuk; Mojović, Miloš; Neumann, Günter; Vučinić, Željko
Nonenzymatic reaction of dihydroxyacetone with hydrogen peroxide enhanced via a Fenton reaction Journal Article
In: Annals of the New York Academy of Sciences, vol. 1048, pp. 461 – 465, 2005.
Abstract | Links | BibTeX | Tags:
@article{Maksimović2005461,
title = {Nonenzymatic reaction of dihydroxyacetone with hydrogen peroxide enhanced via a Fenton reaction},
author = {Vuk Maksimović and Miloš Mojović and Günter Neumann and Željko Vučinić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-25144438518&doi=10.1196%2fannals.1342.067&partnerID=40&md5=68a6ddb9953ecf969461a1912870520e},
doi = {10.1196/annals.1342.067},
year = {2005},
date = {2005-01-01},
journal = {Annals of the New York Academy of Sciences},
volume = {1048},
pages = {461 – 465},
abstract = {An analysis of the reaction of dihydroxyacetone with hydrogen peroxide was performed using HPLC with electrochemical and spectrophotometric detection and EPR spectroscopy of the reactants and products. Glycolate production in such a reaction has been documented, and the glycolate yield analyzed at different pH values. The participation of hydroxyl free radical is shown with DEPMPO spin trap. Two types of mechanisms are proposed, one at higher pH values and pronounced participation of free radicals (enhanced by the presence of metal ions and Fenton reaction) and the other at lower pH values, with decreased free radical production and lower glycolate yield. © 2005 New York Academy of Sciences.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
An analysis of the reaction of dihydroxyacetone with hydrogen peroxide was performed using HPLC with electrochemical and spectrophotometric detection and EPR spectroscopy of the reactants and products. Glycolate production in such a reaction has been documented, and the glycolate yield analyzed at different pH values. The participation of hydroxyl free radical is shown with DEPMPO spin trap. Two types of mechanisms are proposed, one at higher pH values and pronounced participation of free radicals (enhanced by the presence of metal ions and Fenton reaction) and the other at lower pH values, with decreased free radical production and lower glycolate yield. © 2005 New York Academy of Sciences.
Bačić, Goran; Mojović, Miloš
EPR spin trapping of oxygen radicals in plants: A methodological overview Journal Article
In: Annals of the New York Academy of Sciences, vol. 1048, pp. 230 – 243, 2005.
Abstract | Links | BibTeX | Tags:
@article{Bačić2005230,
title = {EPR spin trapping of oxygen radicals in plants: A methodological overview},
author = {Goran Bačić and Miloš Mojović},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-25144448116&doi=10.1196%2fannals.1342.021&partnerID=40&md5=9546b82c7ac3c70df190c2a11beaa8cb},
doi = {10.1196/annals.1342.021},
year = {2005},
date = {2005-01-01},
journal = {Annals of the New York Academy of Sciences},
volume = {1048},
pages = {230 – 243},
abstract = {We present a brief account of the difficulties involved in detection of oxygen free radicals in plants and give a rationale for using the EPR spin trapping technique in such studies. Comparative analysis of characteristics of different spin traps is given, having in mind their suitability in trapping oxygen-centered free radicals. Certain technical aspects of EPR experiments related to successful trapping of free radicals are discussed. Previous studies of trapping of oxygen radicals in plants are reviewed in terms of how efficient the experimental approach employed has been in their detection and how this influences conclusions about the mechanisms of their production. In addition, we analyze the potential of spin labels in the analysis of free radical production in plants and demonstrate that the combination of EPR spin traps and spin labels is extremely efficient for this purpose. © 2005 New York Academy of Sciences.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We present a brief account of the difficulties involved in detection of oxygen free radicals in plants and give a rationale for using the EPR spin trapping technique in such studies. Comparative analysis of characteristics of different spin traps is given, having in mind their suitability in trapping oxygen-centered free radicals. Certain technical aspects of EPR experiments related to successful trapping of free radicals are discussed. Previous studies of trapping of oxygen radicals in plants are reviewed in terms of how efficient the experimental approach employed has been in their detection and how this influences conclusions about the mechanisms of their production. In addition, we analyze the potential of spin labels in the analysis of free radical production in plants and demonstrate that the combination of EPR spin traps and spin labels is extremely efficient for this purpose. © 2005 New York Academy of Sciences.
Mojović, Miloš; Spasojević, Ivan; Bačić, Goran
Detection of hydrogen atom adduct of spin-trap DEPMPO. The relevance for studies of biological systems Journal Article
In: Journal of Chemical Information and Modeling, vol. 45, no. 6, pp. 1716 – 1718, 2005.
Abstract | Links | BibTeX | Tags:
@article{Mojović20051716,
title = {Detection of hydrogen atom adduct of spin-trap DEPMPO. The relevance for studies of biological systems},
author = {Miloš Mojović and Ivan Spasojević and Goran Bačić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-28944439903&doi=10.1021%2fci050173d&partnerID=40&md5=ad8614aa10785184910cfbae82e481df},
doi = {10.1021/ci050173d},
year = {2005},
date = {2005-01-01},
journal = {Journal of Chemical Information and Modeling},
volume = {45},
number = {6},
pages = {1716 – 1718},
abstract = {We proposed EPR spectroscopy using spin-trap DEPMPO as a novel method for the detection of a hydrogen atom (*H) produced by chemical and biological systems. In complex EPR spectra of DEPMPO adducts in biological systems, spectral lines of unknown origin have been observed. We have assumed (Bačič, G.; Mojović, M. Ann. N. Y. Acad. Sci. 2005, 1048, 230-243) that those lines represent the spectrum of a hydrogen atom (*H) adduct i.e., DEPMPO/H. An electrochemical system known to produce only *H radicals was used here in order to obtain a separate spectrum of the DEPMPO/H adduct. An acquired spectrum as well as a computer spectral simulation of the DEPMPO/H adduct showed considerable resemblance with additional lines in the EPR spectra of DEPMPO adducts in biological systems-plant plasma membranes and cell walls. This shows that such a radical is produced by plants as well as that DEPMPO is suitable for detection in both electrochemical and biological systems. © 2005 American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We proposed EPR spectroscopy using spin-trap DEPMPO as a novel method for the detection of a hydrogen atom (*H) produced by chemical and biological systems. In complex EPR spectra of DEPMPO adducts in biological systems, spectral lines of unknown origin have been observed. We have assumed (Bačič, G.; Mojović, M. Ann. N. Y. Acad. Sci. 2005, 1048, 230-243) that those lines represent the spectrum of a hydrogen atom (*H) adduct i.e., DEPMPO/H. An electrochemical system known to produce only *H radicals was used here in order to obtain a separate spectrum of the DEPMPO/H adduct. An acquired spectrum as well as a computer spectral simulation of the DEPMPO/H adduct showed considerable resemblance with additional lines in the EPR spectra of DEPMPO adducts in biological systems-plant plasma membranes and cell walls. This shows that such a radical is produced by plants as well as that DEPMPO is suitable for detection in both electrochemical and biological systems. © 2005 American Chemical Society.
Mojović, Miloš; Spasojević, Ivan; Vuletić, Mirjana; Vučinić, Željko; Bačić, Goran
An EPR spin-probe and spin-trap study of the free radicals produced by plant plasma membranes Journal Article
In: Journal of the Serbian Chemical Society, vol. 70, no. 2, pp. 177 – 186, 2005.
Abstract | Links | BibTeX | Tags:
@article{Mojović2005177,
title = {An EPR spin-probe and spin-trap study of the free radicals produced by plant plasma membranes},
author = {Miloš Mojović and Ivan Spasojević and Mirjana Vuletić and Željko Vučinić and Goran Bačić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-25144441582&doi=10.2298%2fJSC0502177M&partnerID=40&md5=2f12dac6d99a81a7aa36c81912db03b3},
doi = {10.2298/JSC0502177M},
year = {2005},
date = {2005-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {70},
number = {2},
pages = {177 – 186},
abstract = {Plant plasma membranes are known to produce superoxide radicals, while the production of hydroxyl radical is thought to occur only in the cell wall. In this work it was demonstrated using combined spin-trap and spin-probe EPR spectroscopic techniques, that plant plasma membranes do produce superoxide and hydroxyl radicals but by kinetically different mechanisms. The results show that superoxide and hydroxyl radicals can be detected by DMPO spin-trap and that the mechanisms and location of their production can be differentiated using the reduction of spin-probes Tempone and 7-DS. It was shown that the mechanism of production of oxygen reactive species is NADH dependent and diphenylene iodonium inhibited. The kinetics of the reduction of Tempone, combined with scavengers or the absence of NADH indicates that hydroxyl radicals are produced by a mechanism independent of that of superoxide production. It was shown that a combination of the spin-probe and spin-trap technique can be used in free radical studies of biological systems, with a number of advantages inherent to them.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Plant plasma membranes are known to produce superoxide radicals, while the production of hydroxyl radical is thought to occur only in the cell wall. In this work it was demonstrated using combined spin-trap and spin-probe EPR spectroscopic techniques, that plant plasma membranes do produce superoxide and hydroxyl radicals but by kinetically different mechanisms. The results show that superoxide and hydroxyl radicals can be detected by DMPO spin-trap and that the mechanisms and location of their production can be differentiated using the reduction of spin-probes Tempone and 7-DS. It was shown that the mechanism of production of oxygen reactive species is NADH dependent and diphenylene iodonium inhibited. The kinetics of the reduction of Tempone, combined with scavengers or the absence of NADH indicates that hydroxyl radicals are produced by a mechanism independent of that of superoxide production. It was shown that a combination of the spin-probe and spin-trap technique can be used in free radical studies of biological systems, with a number of advantages inherent to them.
Mojović, Miloš; Vuletić, Mirjana; Bačić, Goran G.
Detection of oxygen-centered radicals using EPR spin-trap DEPMPO: The effect of oxygen Journal Article
In: Annals of the New York Academy of Sciences, vol. 1048, pp. 471 – 475, 2005.
Abstract | Links | BibTeX | Tags:
@article{Mojović2005471,
title = {Detection of oxygen-centered radicals using EPR spin-trap DEPMPO: The effect of oxygen},
author = {Miloš Mojović and Mirjana Vuletić and Goran G. Bačić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-25144438044&doi=10.1196%2fannals.1342.069&partnerID=40&md5=4fd9ec4cc020b2163dc91a51ef38f486},
doi = {10.1196/annals.1342.069},
year = {2005},
date = {2005-01-01},
journal = {Annals of the New York Academy of Sciences},
volume = {1048},
pages = {471 – 475},
abstract = {Studies of the ability of the EPR spin trap DEPMPO to detect both superoxide and hydroxyl radicals produced by systems in vitro and in vivo are presented. Experiments using free radical-generating systems confirmed the suitability of the EPR spin trapping technique but also revealed the existence of an undesirable conversion of DEPMPO/OOH into DEPMPO/OH adducts. The rate of conversion decreases with oxygenation, and the production of oxygen-centered radicals increases. However, this property of DEPMPO does not have a significant influence on its ability to independently detect radicals produced by plant plasma membranes. Since the adduct conversion appears to be rather slow compared to radical generation, we conclude that the DEPMPO spin-trap can be efficiently used for detection of oxygen-centered radicals produced by systems in vivo, as demonstrated for isolated plasma membranes. © 2005 New York Academy of Sciences.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Studies of the ability of the EPR spin trap DEPMPO to detect both superoxide and hydroxyl radicals produced by systems in vitro and in vivo are presented. Experiments using free radical-generating systems confirmed the suitability of the EPR spin trapping technique but also revealed the existence of an undesirable conversion of DEPMPO/OOH into DEPMPO/OH adducts. The rate of conversion decreases with oxygenation, and the production of oxygen-centered radicals increases. However, this property of DEPMPO does not have a significant influence on its ability to independently detect radicals produced by plant plasma membranes. Since the adduct conversion appears to be rather slow compared to radical generation, we conclude that the DEPMPO spin-trap can be efficiently used for detection of oxygen-centered radicals produced by systems in vivo, as demonstrated for isolated plasma membranes. © 2005 New York Academy of Sciences.
2004
Mojović, Miloš; Vuletić, Mirjana; Bačić, Goran G.; Vučinić, Željko
Oxygen radicals produced by plant plasma membranes: An EPR spin-trap study Journal Article
In: Journal of Experimental Botany, vol. 55, no. 408, pp. 2523 – 2531, 2004.
Abstract | Links | BibTeX | Tags:
@article{Mojović20042523,
title = {Oxygen radicals produced by plant plasma membranes: An EPR spin-trap study},
author = {Miloš Mojović and Mirjana Vuletić and Goran G. Bačić and Željko Vučinić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-11144262180&doi=10.1093%2fjxb%2ferh266&partnerID=40&md5=89274629049d693354f57cd006e466d1},
doi = {10.1093/jxb/erh266},
year = {2004},
date = {2004-01-01},
journal = {Journal of Experimental Botany},
volume = {55},
number = {408},
pages = {2523 – 2531},
abstract = {Plant plasma membranes are known to produce superoxide radicals, while the production of the hydroxyl radical, previously detected in complex plant tissues, is thought to occur in the cell wall. The mechanism of production of superoxide radicals by plant plasma membranes is, however, under dispute. It is shown, using electron paramagnetic resonance spectroscopy with a 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide spintrap capable of differentiating between radical species, that isolated purified plasma membranes from maize roots produce hydroxyl radicals besides superoxide radicals. The results argue in favour of superoxide production through an oxygen and diphenylene iodonium-sensitive, NADH-dependent superoxide synthase mechanism, as well as through other unidentified mechanism(s). The hydroxyl radical is produced by an oxygen-insensitive, NADH-stimulated mechanism, which is enhanced in membranes in which the superoxide synthase is incapacitated by substrate removal or inhibition.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Plant plasma membranes are known to produce superoxide radicals, while the production of the hydroxyl radical, previously detected in complex plant tissues, is thought to occur in the cell wall. The mechanism of production of superoxide radicals by plant plasma membranes is, however, under dispute. It is shown, using electron paramagnetic resonance spectroscopy with a 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide spintrap capable of differentiating between radical species, that isolated purified plasma membranes from maize roots produce hydroxyl radicals besides superoxide radicals. The results argue in favour of superoxide production through an oxygen and diphenylene iodonium-sensitive, NADH-dependent superoxide synthase mechanism, as well as through other unidentified mechanism(s). The hydroxyl radical is produced by an oxygen-insensitive, NADH-stimulated mechanism, which is enhanced in membranes in which the superoxide synthase is incapacitated by substrate removal or inhibition.
2000
Petković, Jelena; Mladenović, Ivana; Vukelić, Nikola; Mojović, Miloš; Bačić, Goran
Lanthanide doped alkaline metal sulphates as candidates for EPR dosimetry Journal Article
In: Journal of the Serbian Chemical Society, vol. 65, no. 10, pp. 743 – 754, 2000.
Abstract | Links | BibTeX | Tags:
@article{Petković2000743,
title = {Lanthanide doped alkaline metal sulphates as candidates for EPR dosimetry},
author = {Jelena Petković and Ivana Mladenović and Nikola Vukelić and Miloš Mojović and Goran Bačić},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034345791&doi=10.2298%2fjsc0010743p&partnerID=40&md5=80728ed866a70109252945e70f2a451d},
doi = {10.2298/jsc0010743p},
year = {2000},
date = {2000-01-01},
journal = {Journal of the Serbian Chemical Society},
volume = {65},
number = {10},
pages = {743 – 754},
abstract = {The applicability of lanthanide doped alkaline metal sulphates as a new type of dosimeters for EPR dosimetery of ionizing radiation has been investigated in an attempt to obtain a dosimeter with better characteristics than the commonly used alanine dosimeter. Irradiation of samples doped with different lanthanides (Y, Ln, Gd) showed that the best sensitivity is obtained using dosimeters doped with Y2(SO4)3. Different procedures for manufacturing dosimeters were studied and an optimum procedure was established. The time stability of the EPR signal of the irradiated Y2(SO4)3 dosimeter was investigated using a 15N-PDT standard and no fading of the EPR signal was observed over at least two weeks. The dose dependence of alanine and Y2(SO4)3 doped K3Na(SO4)2 dosimeters irradiated in the range 20 Gy - 200 kGy was analysed using a combination of 1-hit and 2-hit mechanisms of free radicals creation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The applicability of lanthanide doped alkaline metal sulphates as a new type of dosimeters for EPR dosimetery of ionizing radiation has been investigated in an attempt to obtain a dosimeter with better characteristics than the commonly used alanine dosimeter. Irradiation of samples doped with different lanthanides (Y, Ln, Gd) showed that the best sensitivity is obtained using dosimeters doped with Y2(SO4)3. Different procedures for manufacturing dosimeters were studied and an optimum procedure was established. The time stability of the EPR signal of the irradiated Y2(SO4)3 dosimeter was investigated using a 15N-PDT standard and no fading of the EPR signal was observed over at least two weeks. The dose dependence of alanine and Y2(SO4)3 doped K3Na(SO4)2 dosimeters irradiated in the range 20 Gy - 200 kGy was analysed using a combination of 1-hit and 2-hit mechanisms of free radicals creation.