Mitsuko Ukai

Free radicals in irradiated pepper: An electron spin resonance study

With electron spin resonance (ESR) spectroscopy, we revealed various free radicals in commercially available pepper in Japan before and after γ-irradiation. The representative ESR spectrum of the pepper is composed of a sextet centered atg=2.0, a singlet at the sameg-value and a singlet atg=4.0. The first signal is attributable to a signal with hyperfine interactions of the Mn2+ ion (hyperfine constant, 7.4 mT). The second signal is due to an organic free radical apparently induced by a sterilization process. The third signal may originate from the Fe3+ ion in the nonheme proteins. The progressive saturation behavior at various microwave power levels indicated quite different relaxation behaviors of those radicals. Namely, the peak intensity of the organic free radical component decreases in a monotonic fashion, whereas the Mn2+ and Fe3+ ESR signals substantially remain constant. This evidences the presence of three independent radicals in the pepper before irradiation. Upon γ-irradiation, a new pair of signals appeared in the pepper. The progressive saturation behavior of the pair peaks after the irradiation showed a quite different behavior as compared with the free radical centered atg=2.0. For the measure of irradiation effects, we propose a universal index for the ESR analysis of irradiated dry foods.

ESR study of free radicals in mango

An electron spin resonance (ESR) spectroscopic study of radicals induced in irradiated fresh mangoes was performed. Mangoes in the fresh state were irradiated with gamma-rays, lyophilized and then crushed into a powder. The ESR spectrum of the powder showed a strong main peak at g=2.004 and a pair of peaks centered at the main peak. The main peak was detected from both flesh and skin specimens. This peak height gradually decreased during storage following irradiation. On the other hand, the side peaks showed a well-defined dose-response relationship even at 9 days post-irradiation. The side peaks therefore provide a useful means to define the irradiation of fresh mangoes.

Free radicals in irradiated wheat flour detected by electron spin resonance

By electron spin resonance (ESR) spectroscopy, we revealed free radicals in wheat flour before and after γ-ray inrradiation and their thermal behavior during heat treatment. The ESR spectrum of wheat flour before irradiation consists of a sextet centered atg=2.0 and a singlet signal at the sameg-value position. The first one is attributable to a signal with hyperfine (hf) interactions of Mn2+ ion (hf constant, 7.4 mT). The second signal originates from the carbon-centered radical. Upon γ-ray irradiation, however, a new signal with two triplet lines at the low- and high-field ends was detected on the Mn2+ sextet lines. We analyzed the triplet ESR lines as due to powder spectra (rhombicg-tensor symmetry) with nitrogen (14N) hf interactions. This indicates that a new organic radical was induced in the conjugated protein portion of wheat flour by γ-ray irradiation. The intensity of the organic free radical atg=2.0 detected in irradiated wheat flour increased monotonically under thermal treatment. The analysis of the time-dependent evolution process on the basis of the theory of transient phenomena as well as the nonlinear least-squares numerical method provided a unique time constant for the radical evolution in wheat flour during thermal treatment.

An electron spin resonance study of radical decay in γ-ray irradiated pepper by thermal treatments

We examined by electron spin resonance (ESR) spectroscopy the thermal decay of radicals as induced by γ-irradiation on pepper. Upon irradiation, the satellite signals were newly induced and appeared at the symmetric positions of the organic free radical, i.e., theg=2.0 signal. Heat treatment decreased the satellite signals exponentially. The ESR signal of the pepper heated for more than 10 min was essentially the same as that before irradiation. To evaluate the radical decay by heat treatment, we formulated a time-dependent master equation. We could evaluate the time constant of the radical decay on the basis of the general solution of the equation together with the non-linear least-squares method.

Kinetic evaluation of spin trapping rate constants of new CYPMPO-type spin traps for superoxide and other free radicals

Abstract CYPMPO (5-(2,2-dimethyl-1,3-propoxyl cyclophosphoryl)-5-methyl-1-pyrroline N-oxide) is a phosphorus containing spin trap that has been useful in aqueous media. Using a kinetic ESR spin trapping technique, we evaluated free radical trapping rate constants of two newly synthesized CYPMPO-type spin traps, including 2,2-dibutyl-substituted CYPMPO (DBCYP) and 5-phenyl-substituted CYPMPO (PhCYP). We investigated the spin trapping of five free radical species, i. e., superoxide, hydroxyl radical, alkoxyl radical, alkyl peroxyl radical and methyl radical. Other than superoxide, spin trapping rate constants of DBCYP and PhCYP are comparable to CYPMPO, ranging from 43.9% to 101% of CYPMPOs corresponding rate constants. However, PhCYPs spin-trapping rate constant against superoxide was 44% higher than that of CYPMPO. The results indicate that DBCYP and PhCYP may be the spin traps as useful as CYPMPO either in aqueous or non-aqueous medium.

Analysis of Relaxation Behavior of Free Radicals in Irradiated Cellulose Using Pulse and Continuous-Wave Electron Spin Resonance

© 2013 Kameya and Ukai, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Analysis of Relaxation Behavior of Free Radicals in Irradiated Cellulose Using Pulse and Continuous-Wave Electron Spin Resonance

Fe-transferrins or their homologues in ex-vivo mushrooms as identified by ESR spectroscopy and quantum chemical calculations: A full spin-Hamiltonian approach for the ferric sextet state with intermediate zero-field splitting parameters

Fe-transferrins/their homologues in ex-vivo mushrooms were identified by ESR spectroscopy at liquid helium temperature, 4 K. The ESR fine-structure signals from Grifola frondosa were analyzed by spectral simulation with a full spin-Hamiltonian approach, determining the spin Hamiltonian parameters of the ferric iron species bound in the biological environment: S = 5/2, g = (2.045, 2.01, 2.235), |D| = 0.28 cm-1, |E/D| = 0.05. The zero-field splitting (ZFS) parameters, D- and E-values, are very close to the reported values, |D| = 0.25 cm-1 and |E/D| = 0.06, for an Fe-transferrin with oxalate anion, and to |D| = 0.25 cm-1 and |E/D| = 0.04 for one with malonate anion in human sera, suggesting that the Fe3+ species are from Fe-transferrins or their homologues. Quantum chemical calculations of the ZFS tensors for Fe-transferrins were carried out. Fe-transferrins/homologues have been identified for all the mushrooms under study, suggesting that such Fe3+ enzymes are widely distributed in mushrooms.

N1, N14-diferuloylspermine as an antioxidative phytochemical contained in leaves of Cardamine fauriei

Most Brassicaceae vegetables are ideal dietary sources of antioxidants beneficial for human health. Cardamine fauriei (Ezo-wasabi in Japanese) is a wild, edible Brassicaceae herb native to Hokkaido, Japan. To clarify the main antioxidative phytochemical, an 80% methanol extraction from the leaves was fractionated with Diaion® HP-20, Sephadex® LH-20, and Sep-Pak® C18 cartridges, and the fraction with strong antioxidant activity depending on DPPH method was purified by HPLC. Based on the analyses using HRESIMS and MS/MS, the compound might be N1, N14-diferuloylspermine. This rare phenol compound was chemically synthesized, whose data on HPLC, MS and 1H NMR were compared with those of naturally derived compound from C. fauriei. All results indicated they were the same compound. The radical-scavenging properties of diferuloylspermine were evaluated by ORAC and ESR spin trapping methods, with the diferuloylspermine showing high scavenging activities of the ROO·, O2·−, and HO· radicals as was those of conventional antioxidants.

Effect of Long-term Storage on Quality Attributes of Onions(Allium cepa) Grown in Hokkaido.

北海道産タマネギ6種について,貯蔵による品種特性の変化を調べた.(1) 貯蔵中にいずれの品種でも固形分,糖度,平均一球重の変動が認められたが,「蘭太郎」,「さらり」では貯蔵による変動が少なかった.これら2種はピルビン酸生成量あるいはその貯蔵中の増加量が少なく,従来のF1種とは異なる性質を示した.最多に栽培されている「スーパー北もみじ」は,冷蔵貯蔵前の11月はピルビン酸生成量,硬度ともに低値を示したが,12月以降は両者とも急激に上昇した.(2) ほとんど全てのタマネギは,長期保存中もソテー加工に適する固形分量およびパウダー加工に適する還元糖量を示した.(3) タマネギの硬度を品種間で比較したが,測定時期(貯蔵期間)により変動し,品種による硬さの位置づけはできなかった.(4) 鱗茎部分の色彩および遊離糖の組成は貯蔵により変動し,その傾向は淡路産タマネギと類似していた.本研究を行うにあたり,北海道産タマネギの品種についてご指導いただいた北海道立北見農業試験場場長宮浦邦晃氏,ならびに試料タマネギの栽培,採取および選定にご協力いただいた同試験場園芸科科長田中静行氏に深く感謝の意を表します.