• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2004.05a
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• pp.118-118
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• 2004

• Journal of The Korean Society of Grassland and Forage Science
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• v.42 no.2
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• pp.114-119
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• 2022

The objective of this study was to determine phosphorus effects on drought stress-induced oxidative stress in Kentucky bluegrass. Drought stress was induced by reducing of water to plants in pots. Two types of phosphorus were applied as potassium phosphate (P) or potassium phosphonate (PA). Application of phosphorus was efficient to ameliorate the adverse effects of drought. Osmotic potential, total chlorophyll and carotenoid content were significantly decreased by drought stress, but was relieved by P or PA application. Superoxide (O₂^•-) concentration was significantly increased more than 14-fold under drought-stressed plants, was accompanied with increase of hydrogen peroxide (H₂O₂) and lipid peroxidation (MDA). However, malondialdehyde (MDA) was much less in P or PA applied plants under drought stress condition. Activities of catalase (CAT), ascorbate peroxidase (APX) and guaiacol-peroxidase (GPX) were largely increased by drought stress and its increase rate was much higher in P or PA applied plants except APX. These results indicate that drought stress-induced oxidative stress is alleviated by P or PA application due to the increase of activities of antioxidant enzymes.

• Molecular & Cellular Toxicology
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• v.5 no.4
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• pp.273-282
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• 2009

Cadmium (Cd) and tributyltin (TBT) are common contaminants of marine and freshwater ecosystems, and can induce the formation of reactive oxygen species (ROS). These ROS can, in turn, cause oxidative stress. In the present study, we investigated time-related effects of Cd (0.05 and 0.1 ppm) and TBT (5 and 10 ppb) treatment on antioxidant enzyme activity, i.e., the activity of superoxide dismutase (SOD) and catalase (CAT) in the gills and digestive glands of the ark shell, Scapharca broughtonii. In addition, hydrogen peroxide ($H_2O_2$) concentrations, lysozyme activity, and glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) levels were measured in the hemolymph. We found that Cd and TBT treatment significantly increased antioxidant enzyme mRNA expression and activity in the digestive glands and gills in a time-dependent manner. In response to the Cd and TBT treatments, antioxidant enzymes mRNA expression and activity increased up to day 5 in the digestive glands and then decreased by day 7. In the gills, antioxidant enzymes mRNA expression and activity increased up to day 3 and then decreased by day 5. Likewise, $H_2O_2$ concentrations significantly increased up to day 5 and then decreased by day 7. Finally, lysozyme activity decreased during the experimental period, whereas GOT and GPT levels were significantly increased in a time-dependent manner. These results suggest that antioxidant enzymes play an important role in decreasing ROS levels and oxidative stress in ark shells exposed to Cd and TBT.

• Preventive Nutrition and Food Science
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• v.13 no.4
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• pp.313-320
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• 2008

Efficiency of a far-infrared radiation (FIR) dryer for drying of citrus by-products (CBPs) was evaluated through their antioxidant activities. The CBPs dried through FIR were enzymatically digested by six carbohydrases (AMG, Celluclast, Pectinase, Termamyl, Ultraflo and Viscozyme) to prepare digests for evaluation of the activities. The total polyphenolic and total flavonoid contents of the digests were determined by colorimetric assays. The AMG digest was selected for the further experiments. The antioxidant potential of the digests were evaluated by DPPH, superoxide, hydroxyl and alkyl radical scavenging activities, $H_2O_2$ scavenging activity, metal chelating, lipid peroxidation inhibition and the reduction of DNA damage. The AMG digest from CBPs dried through FIR at $50^{\circ}C$ showed strong antioxidant activities in DPPH, superoxide, hydrogen peroxide, alkyl and metal chelating assays while all the digests showed strong lipid peroxidation activities. Further, enzymatic digests showed remarkable inhibitory activities against $H_2O_2$-induced DNA damage. Hence, the data obtained using different in vitro models clearly established the antioxidant potential of enzymatic digests from CBPs dried through FIR. Furthermore, they can be used as a source of natural antioxidants; hence, far-infrared radiation drying is a viable method for transforming wet CBPs into a dried form without destroying the bioactive components.

• Journal of the Korean Chemical Society
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• v.37 no.4
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• pp.462-469
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• 1993

The electrocatalytic reduction of dioxygen is investigated by cyclic voltammetry and chronoamperometry at glassy carbon electrode and carbon microelectrode coated with a variety of cobalt phenylporphyrins. The n value obtained at carbon microelectrode is slightly different from that determined at glassy carbon electrode. Dioxygen reduction catalyzed by the monormeric porphyrin Co(II)-TPP mainly occurs through the $2e^-$ reduction pathway resulting in the formation of hydrogen peroxide, electrocatalytic process carries out $4e^-$ reduction pathway of dioxygen to $H_2O$ at the electrodes coated with bis-cobalt phenylporphyrins. The electrocatalytic reduction of dioxygen is irreversible and diffusion controlled.

• Journal of Aerospace System Engineering
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• v.14 no.3
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• pp.24-31
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• 2020

A study on the H2O2 based low toxic hypergolic propellant was conducted. The fuel candidates were chosen as a mixture of Amine solvent and reactive additive. The analytical performance was calculated via the NASA CEA code and 96% Isp of the NTO/UDMH was confirmed. The ignition delay measurement with drop test was performed and all candidates showed less than 10 ms in the best performance cases. Based on these results, the feasibility of high response H2O2 based low toxic hypergolic propellant was confirmed.

• Nuclear Engineering and Technology
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• v.9 no.1
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• pp.1-6
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• 1977

Monoiodobromosulfophthalein-$^{131}$ I (MIBSP-$^{131}$ I), one of the useful radiopharmaceuticals for liver function studies, has been prepared by a simple isotope exchange between the MIBSP and the molecular iodine-$^{131}$ I in phosphate buffer, pH 5.3. The pooled cold MIBSP was prepared by a normal iodination of BSP using iodine monochloride, and separated from the iodination mixture by applying a Sephadex LH-20 chromatography. At 10$0^{\circ}C$, the exchange rate was so fast that the reaction could be terminated in 5 min to show upto 95% yield. The final product could be obtained simply by further heating for about 5 min in a boiling water bath in the presence of a small amount of hydrogen peroxide, and subsequent pH adjustment and membrane filtration.

• Journal of the Korean Chemical Society
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• v.46 no.6
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• pp.509-514
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• 2002

A method to determin Fe(II) and Fe(III) ion in aqueous solution by chemiluminescence method using a stopped flow system has been studied. The method is based on the increased chemiluminescence intensity with the addition of Fe(III) ion to a solution of lucigenin and hydrogen peroxide. The effects of KOH concentration, flow rate of reagents, $H_2O_2$ concentration and citric acid concentration used for the masking of Fe(II) ion on the chemilu-minescence intensity have been investigated. The calibration curve for total Fe was linear over the range from 1.0${\times}$$10^{-6}$ M to 1.0${\times}$$10^{-4}$M, coefficient of correlation was 0.996 and the detection limit was 1.0${\times}$$10^{-7}$M under the optimal exper-imental conditions of 4.0 M, 2.0 M, 3.5 mL/min for the concentration of $H_2O_2,$ KOH and flow rate of reagents, respec-tively. The calibration curve for Fe(Ⅲ) was linear over the range from 1.0${\times}$$10^{-6}$M to 1.0${\times}10^{-4}$ M, the coefficient of correlation was 0.997 and the detection limit was 5.0${\times}$$10^{-7}$M under the optimal experimental conditions.

• Food Science and Biotechnology
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• v.18 no.1
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• pp.249-252
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• 2009

Two-dimensional gel electrophoresis (2-DE) was employed to assess the thermo-tolerance characteristics of Bifrdobacterium infantis ATCC 27920 to mild heat adaptation. When exposed to various heat levels, pH, and hydrogen peroxide ($H_2O_2$) stress conditions, B. infantis ATCC 27920 exhibited high level of stress resistance. Under mild-heat treatment ($46^{\circ}C$), no significant change in viability level was observed after 2 hr. Interestingly, improved viability was observed in mild-heat adapted ($46^{\circ}C$ for 1 hr) cultures exposed to $55^{\circ}C$, in comparison to control experiments. Viability was not affected by pH, bile, and $H_2O_2$ stress conditions. 2-DE analysis revealed those mild-heat adaptation up-regulated 4 proteins and down-regulated 3 proteins. Among these protein spots, isopropyhnalate dehydratase (leuD), glycosyltransferase (glgA), and ribosomal protein L5 (rp1E) were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALD1-TOF/MS).

• Journal of Microbiology and Biotechnology
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• v.33 no.5
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• pp.591-599
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• 2023

Fisetin is a bioactive flavonol molecule and has been shown to have antioxidant potential, but its efficacy has not been fully validated. The aim of the present study was to investigate the protective efficacy of fisetin on C2C12 murine myoblastjdusts under hydrogen peroxide (H₂O₂)-induced oxidative damage. The results revealed that fisetin significantly weakened H₂O₂-induced cell viability inhibition and DNA damage while blocking reactive oxygen species (ROS) generation. Fisetin also significantly alleviated cell cycle arrest by H₂O₂ treatment through by reversing the upregulation of p21WAF1/CIP1 expression and the downregulation of cyclin A and B levels. In addition, fisetin significantly blocked apoptosis induced by H₂O₂ through increasing the Bcl-2/Bax ratio and attenuating mitochondrial damage, which was accompanied by inactivation of caspase-3 and suppression of poly(ADP-ribose) polymerase cleavage. Furthermore, fisetin-induced nuclear translocation and phosphorylation of Nrf2 were related to the increased expression and activation of heme oxygenase-1 (HO-1) in H₂O₂-stimulated C2C12 myoblasts. However, the protective efficacy of fisetin on H₂O₂-mediated cytotoxicity, including cell cycle arrest, apoptosis and mitochondrial dysfunction, were greatly offset when HO-1 activity was artificially inhibited. Therefore, our results indicate that fisetin as an Nrf2 activator effectively abrogated oxidative stress-mediated damage in C2C12 myoblasts.