Thymidine Free Radicals Generated During Metallo-phthalocyanine Photosensitization: A Comparison with γ-radiation

1995 ◽  
Vol 68 (1) ◽  
pp. 29-36 ◽  
Author(s):  
T.G. Gantchev
Keyword(s):  
Free Radicals ◽  
Γ Radiation

Electron Spin Resonance Studies of Reactions of Photo-generated Organic Radicals with Hydrogen Peroxide in Aqueous Solution

1971 ◽  
Vol 49 (24) ◽  
pp. 4005-4016 ◽  
Author(s):  
C. E. Burchill ◽  
P. W. Jones
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Free Radicals ◽  
Electron Spin Resonance ◽  
Organic Radicals ◽  
Chain Reaction ◽  
Direct Photolysis ◽  
Ketyl Radical ◽  
Γ Radiation ◽  
Spin Resonance

The reactions with H2O2 of free radicals derived from 2-propanol, methanol, dimethoxymethane, and tetrahydrofuran have been investigated by e.s.r. using in-cavity photolysis with acetone photosensitization to generate the radicals in flowing aqueous solutions. The variation in the concentrations of the radicals derived from a particular solute with addition of H2O2 is attributed to the selective oxidation of one radical by H2O2, propagating a secondary chain reaction, e.g.,[Formula: see text]The rate constant for the oxidation of the acetone ketyl radical ((CH3)2ĊOH) by H2O2 is estimated to be 5 × 105 M−1 s−1.The results and conclusions of this study are demonstrated to be consistent with the results of previous investigations employing γ-radiation, photolysis, and the reaction of Ti(III) with H2O2 for initiation.Results are also reported for the direct photolysis of aqueous malonic acid in the presence of H2O2.

scholarly journals Production of Free Radicals from Adamantane by High Energy Irradiation

1972 ◽  
Vol 27 (11) ◽  
pp. 1289-1293 ◽  
Author(s):  
W. G. Filby ◽  
K. Günther
Keyword(s):  
Free Radicals ◽  
Room Temperature ◽  
High Energy ◽  
Γ Radiation ◽  
Energy Irradiation ◽  
High Energy Irradiation

The nature and properties of radicals produced by the action of electron and γ-radiation on adamantane have been investigated. Radicals produced by irradiation at 77°K are stable to around room temperature, while irradiation at the latter temperature yields well resolved spectra of species stable to about 130°C. The significance of the latter, assigned as the 1-adamantyl radical, in the formation of trapped radicals is discussed.

scholarly journals Free Radical Chemistry of White Phosphorus: γ-Irradiation of P4 in Bromoform

1968 ◽  
Vol 23 (7) ◽  
pp. 916-921 ◽  
Author(s):  
P. Airey ◽  
H. Drawe ◽  
A. Henglein
Keyword(s):  
Free Radicals ◽  
White Phosphorus ◽  
High Yield ◽  
Red Phosphorus ◽  
Γ Irradiation ◽  
Γ Radiation ◽  
Chain Reactions ◽  
Phosphorus Containing ◽  
High Yields ◽  
Free Radical Chemistry

CHBr2PBr2 and (CHBr2)2PBr are formed in high yields and in preparatively useful amounts when solutions of white phosphorus in bromoform are exposed to γ-radiation. In the first stages of irradiation, a red phosphorus containing many groups from the solvent is the only reaction product. About 1000 molecules of P4 are consumed per 100 eV of energy absorbed. In the later stages of irradiation, free radicals from the solvent attack this red phosphorus and lead to the formation of bromophosphines in high yield. Chain reactions are formulated for the formation of both the red phosphorus and the bromophosphines.

Inhibition of radiation-induced clastogenicity by Aegle marmelos (L.) Correa in mice bone marrow exposed to different doses of γ-radiation

2007 ◽  
Vol 26 (2) ◽  
pp. 111-124 ◽  
Author(s):  
G.C. Jagetia ◽  
P. Venkatesh
Keyword(s):  
Bone Marrow ◽  
Body Weight ◽  
Free Radicals ◽  
Fluorescent Probe ◽  
Peak Level ◽  
Aegle Marmelos ◽  
Γ Radiation ◽  
Post Irradiation ◽  
Radiation Induced ◽  
Different Doses

The frequency of micronucleated polychromatic (MPCE), normochromatic erythrocytes (MNCE), and polychromatic/normochromatic erythrocyte ratio (PCE/NCE), was studied in the bone marrow of mice orally administered with 0, 200, 225, 250, 275 and 300 mg/kg body weight of hydroalcoholic leaf extract of Aegle marmelos (AME). Treatment of mice with AME, once daily for 5 consecutive days, before exposure to 2 Gy resulted in a significant decline in the frequency of MPCE when compared to the non-drug-treated irradiated control. The greatest reduction in MPCE was observed for 250 mg/kg body weight AME, accompanied by the highest polychromatic erythrocyte to normochromatic erythrocyte ratio, in comparison with the non-drug-treated irradiated control. Therefore, further studies were carried out using this dose of AME, where the animals were administered with 250 mg/kg body weight of AME before exposure to 0, 0.5, 1, 2, 3 and 4 Gy of γ-radiation and evaluated at 12, 24, 36 and 48 hours post-irradiation. Whole body irradiation of mice to different doses of γ-radiation resulted in a dose-dependent increase in the frequency of MPCE at all post-irradiation times. Treatment of 250 mg/kg AME orally (p.o.) before irradiation significantly reduced the frequency of MPCE at all post-treatment times. The frequency of MPCE increased with time, reached a peak level at 24 hours, and declined thereafter. The occurrence of MNCE has also shown a pattern similar to MPCE, except that the MNCE frequency reached a peak level by 48 hours. The AME significantly reduced the frequency of MNCE at all post-irradiation times, when compared to the non-drug-treated irradiated group. Treatment of mice with AME before exposure to different doses of γ-radiation resulted in the inhibition of a radiation-induced decline in the PCE/NCE ratio, when compared with the concurrent irradiated controls. To gain insight into the mechanism of action, AME was tested for its antioxidant effects in cell-free chemical systems using H2O 2/FeSO4 to generate hydroxyl (◦OH) radicals, which were measured by a fluorescent probe, 2V, 7V-dichlorofluorescin diacetate (DCFH/DA). Xanthine/xanthine oxidase was used to generate superoxide (O2◦-) anion radical, which was measured by a fluorescent probe dihydroethidium (DHE). AME significantly reduced fluorescence in a concentration dependent manner, indicating its efficacy to scavenge free radicals. Our results demonstrate that one of the mechanism of reduction in the radiation-induced DNA damage in mice bone marrow by AME may be due to scavenging of free radicals and elevation in the antioxidant status, as previously reported. Human & Experimental Toxicology (2007) 26, 111-124

scholarly journals The effect of mechanochemical activation and γ-radiation to a depth of coal catalytic hydrogenation of deposit Mamyt

2019 ◽  
pp. 20-26
Author(s):  
Zhaksyntay Kairbekov ◽  
Saltanat Suimbayeva ◽  
Indira Jeldybayeva ◽  
Murtezaoglu Kirali ◽  
Yelmira Yermoldina
Keyword(s):  
Free Radicals ◽  
Radiation Effect ◽  
Mechanochemical Activation ◽  
Functional Dependence ◽  
Electron Flow ◽  
Maximum Yield ◽  
Linear Regression Method ◽  
Iron Compounds ◽  
Γ Radiation ◽  
Liquid Products

This article presents the results of the mechanochemical activation of coal in a shock-grinding-type mill and the γ-radiation effect of a stream of electrons at the LU-6 electron accelerator. It was established that during the hydrogenation of dispersed coal, the yield of both total liquid products and coal distillates of various fractional composition increases. The maximum yield of liquid products (69.2 wt.%), gasoline (13.9 wt.%) and diesel (18.7 wt.%) fractions was observed during the hydrogenation of crushed coal for 30 min. It has been shown that the irradiation of coal with an electron flow (an irradiation dose of 150 kGy) also increases its reactivity in the process of hydrogenation, and also promotes the formation of free radicals and changes in iron compounds that make up the coal hydrogenation catalyst based on natural bauxite from the Turgai deposit. The non-linear regression method established the functional dependence of the yield of liquid products on the radiation dose, on the time of mechanical activation and on the concentration of free radicals, which are of an extreme nature.

In vivo spin trapping of free radicals generated in brain, spleen, and liver during γ radiation of mice

1986 ◽  
Vol 244 (1) ◽  
pp. 156-160 ◽  
Author(s):  
Edward K. Lai ◽  
Carol Crossley ◽  
Rajagopalan Sridhar ◽  
Hara P. Misra ◽  
Edward G. Janzen ◽  
...  
Keyword(s):  
Free Radicals ◽  
Spin Trapping ◽  
Γ Radiation

scholarly journals Influence of a Modified Plant Extract on Activity of Antioxidant Enzymes and Concentration of Pigments in Gamma-Irradiated Plants of Maize and Wheat

2018 ◽  
Vol 72 (1) ◽  
pp. 38-42
Author(s):  
Ibrahim Azizov ◽  
Elshan Shamilov ◽  
Asim Abdullayev ◽  
Zohra Muslimova ◽  
Gunel Mamedli ◽  
...  
Keyword(s):  
Antioxidant Enzymes ◽  
Free Radicals ◽  
Plant Extract ◽  
Photosynthetic Pigment ◽  
Average Dose ◽  
Γ Irradiation ◽  
Dose Power ◽  
Γ Radiation ◽  
Gamma Irradiated ◽  
Object Of Study

Abstract The influence of a medicinal plant extract, immobilised by ligands, on the activity of antioxidant enzymes and photosynthetic pigment concentration of wheat and maize was studied. The object of study was seed of drought-resistant firm durum wheat (Triticum durum Desf.) and maize (Zea mays L.). Seeds were subjected to general uniform γ-radiation from a 60Co source on a Rkhund installation at average dose power of MD = 0.306 Gy/sec. Before radiation seeds were treated in modified extract from medicinal plants. The treatment of seeds with 0.1 and 0.01% solution of modified extract from Hypericum, Dandelion, and Calendula caused significant reduction in processes initiated by radiation and in formation of free radicals. On the basis of the obtained results it was concluded that the used modified plant extract collection had a protective effect, reducing the amount of free radicals produced by γ-irradiation.

Strahlenchemische Erzeugung und optische Absorptionsspektren organischer Schwefelradikale in organischen Gläsern bei —196 °C

1966 ◽  
Vol 21 (7) ◽  
pp. 632-642 ◽  
Author(s):  
J. Wendenburg ◽  
H. Möckel ◽  
A. Granzow ◽  
A. Henglein
Keyword(s):  
Hydrogen Sulfide ◽  
Free Radicals ◽  
Negative Ions ◽  
Visible Range ◽  
Radical Ions ◽  
Free Electrons ◽  
Absorption Bands ◽  
Broad Absorption ◽  
Γ Radiation ◽  
Positive Ions

Organic disulfides, mercaptans, sulfides and hydrogen sulfide have been exposed to γ-radiation in glasses of methyltetrahydrofuran or hydrocarbons at -196 °C. Absorptions have been observed which are attributed to either radicals of the type RS· or to addition complexes of these radicals to S-containing molecules or ions (for example to RS-SR- radical ions). In the case of disulfides. the S-radicals were produced by dissociative capture of electrons from the ionization of the glassy solvent. In the case of mercaptans, the sulphur radicals were formed via H-abstraction by free radicals from the radiolysis of the solvent, when the irradiated glasses were slowly warmed up. HS was formed this way in H2S containing irradiated glasses. The electron capture in benzylmercaptan, dibenzyldisulfide, and dibenzylsulfide partially leads to the benzylradical. Several new absorption bands have been observed which are tentatively attributed to negative ions: C6H5SH⊖ from phenylmercaptan (8100 A), C6H5SC6H5e from diphenylsulfide (broad absorption over the visible range), C6H5CHS⊖ from dibenzylsulfide (~ 3900 A). Carbontetrachloride simultaneously present in the glass was found to inhibit all reactions of free electrons, while the reactions of free radicals during warming up were not suppressed.Glasses of a methylcyclohexane-isopentane mixture containing olefins were found to absorb strongly between 7000 and 9000 A. These absorptions are attributed to positive ions. The absorption of ionized or protonated olefins occurs at longer wave lengths with decreasing number of Η-atoms at the carbon atoms of the double bond. Absorption by positive ions was also observed for diphenyldisulfide (8500 A), and for diallyldisulfide (6840 A). Small amounts of substances which can readily be protonated (such as n-propanol or methyltetrahydrofuran) decrease the intensity of the absorption bands of positive ions.

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