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Evaluation of Hydroxyl Radical and Alkyl-oxy Radical Scavenging Activity of Coffee by ESR Spin Trapping Method 被引量:2
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作者 Hiromi Kameya 《Journal of Food Science and Engineering》 2017年第6期305-311,共7页
We evaluated the hydroxyl and alkyl-oxy radical scavenging activity of instant coffee using an electron spin resonance (ESR) spin-trapping method, which was based the spin-trapping reagent 5-(2,2-dimethy-l,3-propox... We evaluated the hydroxyl and alkyl-oxy radical scavenging activity of instant coffee using an electron spin resonance (ESR) spin-trapping method, which was based the spin-trapping reagent 5-(2,2-dimethy-l,3-propoxycyclophosphoryl)-5-methyl-l-pyrroline N-oxide (CYPMPO). In this method, very pure hydroxyl and alkyl-oxy radicals were generated by illuminating a phosphate buffer solution containing hydrogen peroxide and 2,2'-azobis (2-amidinopropane) dihydrochloride with a Hg-Xe arc lamp. The ESR adduct signal was sensitive and very stable. We concluded that instant coffee has high hydroxyl radical and alkyl-oxy radical scavenging activity. 展开更多
关键词 Radical scavenging COFFEE spin trapping electron spin resonance.
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Spin Trapping of the Phosphorus-centered Radicals Generated from Hydrogen Abstraction Reaction by 2,2-Diphenyl-1-picrylhydrazyl
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作者 Yoshimi Sueishi and Yuko Nishihara (Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushima Naka, Okayama 700-8530, Japan) 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 2000年第4期313-319,共7页
Two kinds of the phosphorus-centered radicals produced from hydrogen atomion by 2, 2-diphenyl-1-picrylhydrazyl(DPPH were trapped by N-tert-butyl-α-phenylnitrone(PBN) and 5, 5-dimethyl-1-pyrroline N-oxide (DMPO), and ... Two kinds of the phosphorus-centered radicals produced from hydrogen atomion by 2, 2-diphenyl-1-picrylhydrazyl(DPPH were trapped by N-tert-butyl-α-phenylnitrone(PBN) and 5, 5-dimethyl-1-pyrroline N-oxide (DMPO), and investigated by means of EPR spectroscopy. The spin adducts with a characteristic hyperfine coupling constant(hfcc) caused by a phosphorus atom were observed. Based on the hfcc values caused by the phosphorus and hydrogen atoms, the con formational positions of the adducts trapped by PBN and DMPO are discussed. 展开更多
关键词 EPR spin trap Phosphorus-centered radical
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Fat and Oil Oxidation by Electron Spin Resonance (ESR) Spin-Trapping Method 被引量:1
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作者 Hiromi Fujino Mitsuko Ukai 《Journal of Food Science and Engineering》 2013年第11期584-591,共8页
Oxidation of fats and oils during storage causes their degradation and loss of nutritional value and appearance. Electron spin resonance (ESR) is the only method that can be used to directly observe the radicals. In... Oxidation of fats and oils during storage causes their degradation and loss of nutritional value and appearance. Electron spin resonance (ESR) is the only method that can be used to directly observe the radicals. In this study, the authors used an ESR spin-trapping method to study the oxidation of triacylglycerols (TAG) containing different fatty acids (FAs) commonly found in food. The ESR adduct signals were analyzed to study the effect of double bonds and the chain length of the FAs of TAG on oxidation. Oxidation was conducted by applying UV irradiation to TAG by dissolving it in N-tert-buthyl〈t-phenylnitrone (PBN), which trapped the radicals induced in the TAG as an ESR adduct signal. The detection was clearly successful. There were no differences in the spectra of tristearin (18:0) and tripalmitin (16:0); thus, it can be concluded that the length of the carbon chain of the FAs of TAG does not affect the oxidation reactions. However, the ESR spectra of tristearin (18:0), triolein (18:1) and trilinolein (18:3) were clearly different due to the presence/absence of a new peak corresponding to new induced radicals, leading to the conclusion that double bonds play a major role in the oxidation reactions of fats and oils. 展开更多
关键词 ESR spin trapping fats and oils TAG OXIDATION UV irradiation.
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Initiation Mechanism of Polymerization of Acryl-amide by Ceric Ion/2-Benzoyl Acetanilide System
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作者 DONG Jian-hua DENG Chao QIU Kun-yuan and FENG Xin-de(Department of Chemistry, Peking University,Beijing,100871) 《Chemical Research in Chinese Universities》 SCIE CAS CSCD 1994年第4期327-332,共6页
he initiation mechanism of ceric ion/2-benzoyl acetanilide system was studiedby means of FT-IR, EPR and kinetic studies which revealed that 2-benzoyl ac-etanilide acts as a very active promotor to the polymerization i... he initiation mechanism of ceric ion/2-benzoyl acetanilide system was studiedby means of FT-IR, EPR and kinetic studies which revealed that 2-benzoyl ac-etanilide acts as a very active promotor to the polymerization initiated by ceric ion.The initiation mechanism was then proposed which involved the complex formationbetween a ceric ion and a l ,3-diketone group or a carbamate group, followed by,thedecomposition of the complex to generate C-centered secondary alkyl radical and N-centered anillido radical, both of which would initiate polymerization of vinylmonomer as the end groups of the polymers formed. 展开更多
关键词 spin trapping and EPR 2-Benzoyl acetanilide Ceric ion Acrylamidepolymerization Intermediate of redox reaction
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Photochemical Method to Evaluate Oxidation Levels in Heat-Treated Vegetable Oil: Comparison with Peroxide-Value and Acid-Value
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作者 Hiromi Kameya Mitsuko Ukai 《Journal of Food Science and Engineering》 2013年第6期299-308,共10页
To determine the degree of oxidation in vegetable oil, a photochemical method using the electron spin resonance (ESR) spin trapping technique was developed, and the results were compared with those obtained using co... To determine the degree of oxidation in vegetable oil, a photochemical method using the electron spin resonance (ESR) spin trapping technique was developed, and the results were compared with those obtained using conventional peroxide-value (PV) and acid-value (AV) methods. Vegetable oil heat-treated were subjected to short UV illumination, and the produced alkyl-oxyl radicals were identified and quantified using the ESR spin trapping technique. ESR signal intensity was used as an indicator of oil oxidation, which monotonically increased as a function of the heat-treatment time. Commercially, available oils were selected and analyzed. The results were compared with those obtained using the PV and AV methods. The present method displayed some analogies with the PV method at least in the early stage of heating. Overall, the present method had highly sensitive and capable of detecting early-stage oxidation in vegetable oil. 展开更多
关键词 ESR spin trapping plant oil peroxy radical UV-illumination.
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Detection of Hydrogen Peroxide Photogenerating from a Hypocrellin B Derivative
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作者 刘光艳 马江华 《Transactions of Tianjin University》 EI CAS 2003年第2期144-147,共4页
In order to f urther improve the photosensitizing activity of hypocrellin B(HB), the complex o f 5,8 di Br HB with Al 3+ was designed and synthesized in high yield. Th e complex of aluminium ion with 5,8 di Br HB is a... In order to f urther improve the photosensitizing activity of hypocrellin B(HB), the complex o f 5,8 di Br HB with Al 3+ was designed and synthesized in high yield. Th e complex of aluminium ion with 5,8 di Br HB is a new water soluble perylene quinonoid derivative with enhanced absorption over HB in the phototherapeutic wi ndow (600-900 nm). Electron paramagnetic resonance (EPR) measurement and 9,10 diphenyl anthracene bleaching methods were used to investigate the photosensiti zing activity of [Al 2(5,8 di Br HB)Cl 4] n in the prese nce of oxygen. Singlet oxygen, superoxide anion radical, hydroxyl radical can be generated by [Al 2(5,8 di Br HB)Cl 4] n photosensit ization. The results showed that the production of hydroxyl radical ( · OH) by [Al 2(5,8 di Br HB)Cl 4] n photosensitization comes from the Fenton Haber Weiss reaction and the decom position of DMPO 1O 2 adduct. Formation of H 2O 2 as one of main intermedi ates in the photogeneration of hydroxyl radical was detected by using the cataly zed oxidation of the DPD reagent by the POD enzyme method. Moreover, the experim ents of EPR spin trap and catalase enzyme excluded the effect of organoperoxide on DPD oxidization. These results further support the proposed mechanism of · OH formation. 展开更多
关键词 complex of aluminium ion with 5 8 di B r HB electron paramagnetic resonance DPD method spin trap hydroxyl radical hydrogen peroxide
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A Novel and Convenient Assay for the Determination of OH Produced by Fenton Reaction
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作者 Zhuo Bin YUAN Zhi Ru MA(Department of Chendstry, Graduate School, USTC, Academia Sinica, Beijing 100039) 《Chinese Chemical Letters》 SCIE CAS CSCD 1998年第6期569-571,共3页
A novel, simple and convenient method for the determination of hydroxyl radicals isestablished. Hydroxyl radicals produced by Fenton reaction is trapped by spin trap reagent phenyl-t-butyl nitrone (PBN), and the free ... A novel, simple and convenient method for the determination of hydroxyl radicals isestablished. Hydroxyl radicals produced by Fenton reaction is trapped by spin trap reagent phenyl-t-butyl nitrone (PBN), and the free radical adduct of PBN can be detected by single sweeposcillopolarography, with its second order derivative cathodic wave at -0.52V vs SCE. Theoptimum experimental conditions for the detemination is discussed, and the scavenging effects ofsome compounds on OH was also studied. 展开更多
关键词 hydroxyl radicals Fenton reaction spin trap reagent PBN electrochemical method
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Toxic effects of chlortetracycline on maize growth,reactive oxygen species generation and the antioxidant response 被引量:6
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作者 Bei Wen Yu Liu +4 位作者 Peng Wang Tong WU Shuzhen Zhang Xiaoquan Shan Jingfen Lu 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2012年第6期1099-1105,共7页
The toxicity of chlortetracycline (CTC) on maize (Zea mays L.) growth and reactive oxygen species (ROS) generation was studied.The root and shoot lengths and fresh weights of maize seedlings were inhibited by CT... The toxicity of chlortetracycline (CTC) on maize (Zea mays L.) growth and reactive oxygen species (ROS) generation was studied.The root and shoot lengths and fresh weights of maize seedlings were inhibited by CTC treatment (p 〈 0.05).Root length was more sensitive than other parameters with the EC 10 value of 0.064 mg/L.The spin trapping technique followed by electron paramagnetic resonance (EPR) analysis was used to quantify the ROS production.The ROS generated in maize roots after exposure to CTC was identified as hydroxyl radical (·OH).The EPR signal intensity correlated positively with the logarithm of CTC concentrations exposed (p 〈 0.05).The dynamic changes of malondialdehyde (MDA) contents and the antioxidative enzyme activities in maize roots were also determined.As compared to the control group,CTC was found to significantly increase MDA content.Treatment of maize roots with the ·OH scavenger sodium benzoate (SB) reduced the MDA content and enhanced the antioxidative enzyme activities.The results demonstrated the harmfulness of CTC at high dose to maize in the early developmental stage,and clarified that the inducement of ·OH is one of the mechanisms of CTC toxicity. 展开更多
关键词 maize (Zea mays L.) CHLORTETRACYCLINE electron paramagnetic resonance (EPR) spin trapping hydroxyl radical (-OH) antioxidant enzyme
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