Radical kinetics and characterization of the free radicals in gamma irradiated red pepper

Electron spin resonance spectral analysis of irradiated royal jelly

The analysis of unpaired electron components in royal jelly was carried out using electron spin resonance (ESR) with the aim to develop a detection method for irradiated royal jelly. The ESR spectrum of royal jelly had natural signals derived from transition metals, including Fe(3+) and Cu(2+), and a signal line near g=2.00. After irradiation, a new splitting asymmetric spectrum with overall spectrum width ca. 10mT at g=2.004 was observed. The intensities of the signals at g=2.004 increased in proportion to the absorbed dose in samples under different storage conditions: fresh frozen royal jelly and dried royal jelly powder at room temperature. The signal intensity of the fresh frozen sample was stable after irradiation. One year after 10kGy irradiation of dried powder, the signal intensity was sevenfold greater than before irradiation, although the intensity continued to steadily decrease with time. This stable radiation-induced radical component was derived from the poorly soluble constituent of royal jelly.

EPR spectroscopy as a tool for investigation of differences in radical status in wheat plants of various tolerances to osmotic stress induced by NaCl and PEG-treatment

Two kinds of wheat genotypes with different tolerance to osmotic stress (NaCl and PEG-treatment) were investigated with biochemical analyses, including the measurements of total antioxidant capacity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, reducing power and starch content. The results were compared with electron paramagnetic resonance (EPR) data concerning the nature and amounts of stable long lived radicals present in the control and stressed plants. In addition, the changes in manganese content upon stress conditions were monitored. Different mechanisms of protection against PEG stress in sensitive and tolerant wheat genotypes were postulated. In sensitive genotypes, electrons were created in excess in stress conditions, and were stabilized by polysaccharide molecules, whereas in tolerant genotypes, protection by antioxidants dominated. Moreover, the quinone-semiquinone balance shifted towards semiquinone, which became the place of electron trapping. NaCl-treatment yielded significant effects mainly in sensitive genotypes and was connected with the changes of water structure, leading to inactivation of reactive oxygen species by water molecules.

An investigation into gamma-ray treatment of shellfish using electron paramagnetic resonance spectroscopy

BACKGROUND

Gamma irradiation is a safe method for the decontamination of shellfish, and its technical feasibility and safety have been endorsed (FAO/IAEA/WHO). In order to implement proper food-processing regulations, the identification of radiation treatment is required. In this study, electron paramagnetic resonance (EPR) spectroscopy was employed to identify the irradiation of seven different types of commonly consumed shellfish.

RESULTS

Characteristics (g factor and signal intensity) of the EPR spectra of control and irradiated samples were recorded in order to clarify the gamma-ray treatment of shellfish. Radiation-specific signals around g = 2.0038 ± 0.0006 (g₁) and g = 1.9996 ± 0.0002 (g₂ and g₃) were observed for all shellfish samples irradiated with absorbed doses of 3 and 6 kGy. The X-ray diffraction (XRD) spectra of some shellfish samples were recorded to investigate their mineral profiles.

CONCLUSION

The EPR spectroscopic results indicated that carbonate minerals were the source of the paramagnetic species that were produced upon irradiation, entrapped in the shellfish and showed radiation-specific asymmetric signals whose intensities increased quantitatively with the absorbed radiation dose. The XRD analysis revealed that aragonite and calcite minerals were present in the shells of shellfish.

Antioxidant response of Arabidopsis plants to gamma irradiation: Genome-wide expression profiling of the ROS scavenging and signal transduction pathways

Arabidopsis presumably has few sensors for gamma-rays and few signal transduction systems that respond to them. In an effort to assess their radiation sensitivity, wild-type (Ler) Arabidopsis plants were irradiated with various doses of gamma-rays at the vegetative (VE) and reproductive (RE) stages. 100Gy treatment induced the higher production of siliques during both the VE and RE stages compared with non-irradiation. Treatments at doses over 200Gy repressed shoot growth, and the plants perished under 800Gy treatment. The results of physiological analysis using electron spin resonance (ESR) and transmission electron microscopy (TEM) revealed that increased doses of gamma-rays induce greater ROS generation. To establish the gene expression profiles after gamma irradiation and for an analysis of the antioxidant response, we employed an oligonucleotide microarray system. Different responses of genes related with ROS scavenging and signal transduction pathways by a gamma irradiation were observed. At least 33 and 42 out of all genes with significantly altered expression were associated with ROS scavenging and signal transduction pathways having an induction or repression ratio cutoff of at least 2-fold, respectively. CAT3 (At1g20620), Ferritin1 (At5g01600), Blue copper binding protein (At5g20230), and AOX putative (At1g32350) were up-regulated regardless of dosage at the VE stage. Reactive oxygen species signaling genes encoding phospholipase, zinc finger protein, WRKY DNA-binding protein, and calcium binding protein were highly expressed, evidencing changes greater than 2-fold. Our transcriptomic profile of the responses of Arabidopsis genes to gamma irradiation showed that plants evidenced altered expressions of many signal transduction and antioxidant genes, as have been seen with other environmental stresses.

A new electron paramagnetic resonance method to identify irradiated soybean

Low-dose gamma irradiation causes minimal changes in food matrix making identification of radiation-processed foods a challenging task. In the present study, soybean samples were irradiated with commercially permitted gamma radiation dose in the 0.25 to 1.0 kGy range for insect disinfestations of food. Immediately after irradiation electron paramagnetic resonance (EPR) spectrum of the skin part of soybean showed a triplet signal (g = 2.0046, hyperfine coupling constant hfcc = 3.0 mT) superimposed on naturally present singlet. These signals were characterized as cellulose and phenoxyl radicals using EPR spectrum simulation technique. Kernel part of the samples exhibited a short-lived, radiation-induced singlet of carbon-centered radical superimposed on naturally present sextet signal of Mn2+. A detailed study on relaxation and thermal behavior of induced radicals in skin part was carried out using EPR spectroscopy. These findings revealed that progressive saturation and thermal characteristics of the induced radicals may be the most suitable parameters to distinguish soybean subjected to radiation dose as low as 0.25 kGy from thermally treated and nonirradiated samples, even after a prolonged period of storage.

Detection of organic free radicals in irradiated Foeniculi fructus by electron spin resonance spectroscopy

Foeniculi fructus were irradiated with an electron beam and organic free radicals were detected by electron spin resonance (ESR) spectroscopy for the purpose of identifying radio-disinfected and sterilized herbal drugs. An ESR single-line spectrum near g = 2.005 was observed in the sample before irradiation. After irradiation, the intensity of the signal near g = 2.005 increased. In addition, two subsignals derived from cellulose radicals were observed approximately 3 mT to either side of the main signal, at g = 2.023 and g = 1.987. The intensity of the subsignal at g = 2.023 was proportional to the absorbed dose of radiation. The decrease in intensity of the signals was considerable 2 weeks after irradiation, and continued to decrease steadily thereafter. Among the signals, the fading of the subsignal at g = 2.023 was relatively small. The intensity of the subsignal at g = 2.023 was detectable for over 1 year in the sample that had been irradiated to the level of disinfection and sterilization. Therefore, organic free radicals in irradiated Foeniculi fructus can be measured rapidly and with high sensitivity by ESR spectroscopy. The stable signal at g = 2.023 is a promising indicator of the detection of irradiated herbal drugs.

Effect of gamma radiation on amlodis and its potential for radiosterilization

In the present work, radiation sensitivity of amlodis (AML) and its active ingredient Amlodipin Besylate (AML-B) were separately investigated by electron spin resonance (ESR) spectroscopy using radiolytic products induced in these drugs. Irradiation in the dose range of 2.5-25kGy did not create any ESR resonance line in AML-B, but it create five characteristic ESR resonance lines associated with more than one radical species in the case of AML. This signal is attributed to the radical species created upon irradiation of inactive ingredients such as microcrystalline cellulose and sodium starch glycolate of AML. Five resonance lines were observed to be divided into three sub groups of different characteristic behaviors associable with three different radical species. Radical species responsible from observed ESR lines were unstable at room and above room temperatures, however, they conserved their identities over a storage period of 92 days. This permitted to discriminate irradiated AML from unirradiated one. A quadratic function was found to describe best the variations of the intensities of observed resonance lines with applied radiation dose. A model based on three tentative radical species with a pyranose ring formed by the rapture of CH bonds in positions 1 and 4 was proposed to explain the observed five lines experimental ESR spectra. AML was considered not providing the characteristic features of a good dosimetric material due to its low radiation yield and relatively fast decays of the created radical species, but very low radiation sensitivity of its active ingredient, namely AML-B makes AML a good candidate for radiosterilization.

ESR detection and dosimetric properties of irradiated naproxen sodium

In the present work, the electron spin resonance (ESR) dosimetric properties of naproxen sodium (NS) was investigated in the dose range of (2.5-25 kGy). Irradiated NS exhibited a very simple ESR spectrum consisting of a broadened antisymmetric single resonance line not saturating up to 2 mW microwave power at room temperature. The sum of two exponential increasing functions associated with two different radicals of different spectroscopic features and relative weights were found best describing experimental dose-response curve. Radiation induced radicals were observed to be very stable at room temperature but the increase in storage temperature increased very appreciably the decay of the contributing radicals. The results of the simulation calculation based on a model of two radicals showed that two carbon dioxide ionic free radicals (*CO(2))(-) of different orientational and environmental features produced by preferential rupture of carboxyl group from the rest of NS molecules in the crystalline matrix, were, likely at the origin of the experimentally observed ESR spectrum. Features such as good time stability of the signal intensity and relatively high radiation yield (G=0.13) were considered providing NS with potential use as dosimetric material in measuring radiation dose in the range of 2.5-25 kGy by ESR technique.

Effects of gamma-irradiation on the free radical and antioxidant contents in nine aromatic herbs and spices

Nine spice and aromatic herb samples (i.e., basil, bird pepper, black pepper, cinnamon, nutmeg, oregano, parsley, rosemary, and sage) were gamma-irradiated at a dose of 10 kGy according to commercial practices. The effects of the disinfection treatment on the content of organic radicals and some nutrients (namely, vitamin C and carotenoids) in the samples were investigated by chromatographic and spectroscopic techniques. Irradiation resulted in a general increase of quinone radical content in all of the investigated samples, as revealed by electron paramagnetic resonance spectroscopy. The fate of these radicals after storage for 3 months was also investigated. The cellulose radical was clearly observed in a few samples. Significant losses of total ascorbate were found for black pepper, cinnamon, nutmeg, oregano, and sage, whereas a significant decrease of carotenoids content was observed for cinnamon, oregano, parsley, rosemary, bird pepper, and sage.

Kinetics of the radicals induced in gamma-irradiated naproxen sodium and apranax. Applicability of ESR technique to monitor radiosterilization of naproxen sodium-containing drugs

In the present work the spectroscopic and kinetic features of the radicals induced in gamma-irradiated naproxen sodium (NS) and apranax (AP) tablet are investigated at room and different temperatures in the dose range of 2.5-25 kGy by electron spin resonance technique (ESR). Radiation produces two different radicals (I, II) in NS quite stable at room temperature but relatively unstable above room temperature, giving rise to a broad singlet centered at g = 2.0057. Dose-response and decay curves associated with the broad singlet were found to follow bi-exponentials. Information concerning the saturation decay rates and activation energies were obtained through the characteristics of these exponentials. Similar calculations were also performed for AP, which contains 550 mg NS as active ingredient, and the applicability of ESR technique for monitoring radiosterilization of AP was discussed.