• Journal of Dairy Science and Biotechnology
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• v.38 no.3
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• pp.134-141
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• 2020

Oxidative stress is a cascade reaction characterized by a significant increase in the amount of oxidized components. Free radicals produced by oxidative stress are one of the common features in several experimental models of disease, and contribute to wide range of neurodegenerative diseases, including Alzheimer's disease. Iron (II) species can participate in the Fenton, and Fenton-like reactions, to react with hydrogen peroxide and generate hydroxyl radical. As iron accumulation and oxidative stress are associated with the pathological progression of neurodegenerative diseases, iron chelation and antioxidant therapies have become strategies to combat these diseases. Due to the complexity of the redox system in vivo, a multifaceted approach may be an attractive therapeutic strategy. Further investigations are highly expected for the prevention and treatment of neurodegenerative diseases in future.

• Journal of Soil and Groundwater Environment
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• v.10 no.4
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• pp.62-69
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• 2005

Removal of 4-chlorophenol (4CP) by natural manganese dioxide (NMD) catalyzed reaction was investigated in this study. Tests were also carried out to evaluate the effects of pH and natural organic matter (NOM) on the degradative oxidation of 4CP. Experimental results proved that NMD was effective for the removal of 4CP. Extensive kinetic analysis suggests that overall oxidation of 4CP by NMD is second-order reaction, the first-order with respect to 4CP, and the first-order with respect to NMD, respectively. Also, 4CP oxidation rates on the Mn-oxide surfaces were highly dependent upon experimental conditions such as pH, initial concentration of 4CP or NMD, and existence of humic acid. As pH increased above PZC of NMD, the reaction rate of 4CP was decreased, due to the low affinity of 4CP on NMD at high pH. At pH lower than PZC of NMD, reaction rate of 4CP was also decreased. It was considered that humic acid was involved in the oxidative coupling reaction of 4CP by NMD, resulting in the enhanced degradation rate of 4CP. This study proved that natural manganese oxide can be effectively applied for the removal of chlorophenols in aqueous phase.

• Journal of the Korean Chemical Society
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• v.37 no.2
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• pp.244-248
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• 1993

Nitroalcohols were prepared by a substitution reaction from the corresponding bromoalcohols. The second nitro group was introduced via different methods depending on the carbon chain length. 3,3-Dinitro-1-propanol was obtained by an intramolecular varient of the alkaline nitration method. Whereas 5,5-dinitro-1-pentanol was given by the catalytic oxidative nitration. 3,3-Dinitro-1-propanol and 5,5-dinitro-1-pentanol were converted to 3,3-dinitro-1,6-hexanediol and 4,4-dinitro-1,8-octanediol via Michael reaction with acrolein followed by the reduction of the resulting aldehydes. Acetyl group was a good protecting group for the substitution reaction while THP was for the catalytic oxidative nitration.

• Bulletin of the Korean Chemical Society
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• v.33 no.9
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• pp.3009-3016
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• 2012

This study evaluated the use of iron-impregnated SBA-15 (Fe/SBA-15) as a catalyst for the oxidative degradation of persistent phenol analogues, such as 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2-nitrophenol (2-NP), 4-nitrophenol (4-NP) and 2,4,6-trichlorophenol (2,4,6-TCP) in water. The oxidation reactions were carried out with reaction time, concentration of the phenols, amount of the catalysts, reaction temperature, pH of the reaction mixture as the process variables with or without using hydrogen peroxide as the oxidizing agent. The conversion achieved with Fe/SBA-15 at 353 K for 2-CP, 4-CP, 2-NP, 4-NP, 2,4,6-TCP was 80.2, 71.2, 53.1, 62.8, 77.3% in 5h with a reactant to $H_2O_2$ mole ratio of 1:1, and 85.7, 65.8, 61.9, 63.7, 78.1% in the absence of $H_2O_2$, respectively. The reactions followed pseudo first order kinetics. The leachability study indicated that the catalyst released very little iron into water and therefore, the possibility of secondary pollution is negligible.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.5
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• pp.867-878
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• 1994

A general overview of the lipid peroxidation and its nutritional significance are presented ,with emphasis on the reaction mechaisms, peroxidized products, further interaction and nutritional/biological deterioration in a series of oxidative process. Overall mechanism with various factors and elements for initiation , propagation and termination of free radical reaction is reviewed and the primary /secondary products of peroxidized lipids are defined. Since these products are potentially reactive substances that can cause deterioration of proteins /amino acids and vitamins (carotene, tocopherols and ascorbic acid etc), mechanism and actual damages of their deterioration in some foods and biological models are outlined. Especially , chemical changes caused by interaction of peroxidized products (related hydroperoxides, radicals and malonaldehye etc) and protein are emphasized here. And also, the detailed mechanisms on radical scavenging of the these vitamins which are the most prominent natural antioxidants are presented . Additionally , the possible roles of peroxidicaed lipids and their secondary products in the process of aging an carcinogenesis are briefly discussed . However, it is important to not that more detailed and integrated studies on the reaction kinetics, energetics of peroxidation, their decomposed products , biochemical interaction potential damaging/aging / carcinogenic effects, protection from their oxidative spoilage and novel antioxidants in food and heterogeneous biological systems will be essential in order to assessing the implication of lipid peroxidation to human nutrition and health.

• Journal of Life Science
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• v.14 no.3
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• pp.406-410
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• 2004

Glyoxal or methylglyoxal was incubated with catalase in 0.24 M sodium phosphate buffer (pH 7.4) at 37$^{\circ}C$. Dicarbonyls modify and inactivate catalase. Plasmid DNA that is directly incubated with glycation propagators, glyoxal and methylglyoxal, showed different DNA mobility shift compared to nomal plasmid DNA. When plasmid DNA is added in Fenton reaction with glycated catalase, plasmid DNA was significantly strand broken and 8-hydroxydeoxyguanosine production was time dependently increased. These results suggest that glycation of antioxidant is synergistic effect to oxidative stress.

• Bulletin of the Korean Chemical Society
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• v.23 no.9
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• pp.1257-1262
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• 2002

$[(C_2B_9H_{11})Mo(CO)_3]_2PPN_2$ $(2{\cdot}PPN_2)$, a new precursor for the oxidative decarbonylation reaction, was synthesized in high yield by the one-electron oxidation reaction of $[(C_2B_9H_{11})Mo(CO)_3]PPN_2$. $2{\cdot}PPN_2$ was structurally characterized, showing a dimeric nature with long (3.321 ${\AA}$) Mo-Mo bonding. Reaction of $2{\cdot}PPN_2$ with sulfur gave the completely decarbonylated product $[(C_2B_9H_{11})Mo({\mu}-S)(S)]_2PPN_2$ ($3{\cdot}PPN_2$). The ligand substitution of the terminal sulfur ligands in $3{\cdot}PPN_2$ to oxygen ligands was carried out with the use of PhIO to give $[(C_2B_9H_{11})Mo({\mu}-S)(O)]_2PPN_2$ ($4{\cdot}PPN_2$). The structures of $3{\cdot}PPN_2$ and $4{\cdot}PPN_2$ were also studied.

• Environmental Engineering Research
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• v.20 no.3
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• pp.205-211
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• 2015

Reduced forms of iron, such as zero-valent ion (ZVI) and ferrous ion (Fe[II]), can activate dissolved oxygen in water into reactive oxidants capable of oxidative water treatment. The corrosion of ZVI (or the oxidation of (Fe[II]) forms a hydrogen peroxide ($H_2O_2$) intermediate and the subsequent Fenton reaction generates reactive oxidants such as hydroxyl radical ($^{\bullet}OH$) and ferryl ion (Fe[IV]). However, the production of reactive oxidants is limited by multiple factors that restrict the electron transfer from iron to oxygen or that lead the reaction of $H_2O_2$ to undesired pathways. Several efforts have been made to enhance the production of reactive oxidants by iron-induced oxygen activation, such as the use of iron-chelating agents, electron-shuttles, and surface modification on ZVI. This article reviews the chemistry of oxygen activation by ZVI and Fe(II) and its application in oxidative degradation of organic contaminants. Also discussed are the issues which require further investigation to better understand the chemistry and develop practical environmental technologies.

• Animal Bioscience
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• v.34 no.2
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• pp.312-319
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• 2021

Objective: Stress-induced cytotoxicity caused by xenobiotics and endogenous metabolites induces the production of reactive oxygen species and often results in damage to cellular components such as DNA, proteins, and lipids. The cytochrome P450 (CYP) family of enzymes are most abundant in hepatocytes, where they play key roles in regulating cellular stress responses. We aimed to determine the effects of the antioxidant compound, methylsulfonylmethane (MSM), on oxidative stress response, and study the cytochrome P450 family 3 subfamily A (CYP3A) gene expression in fetal horse hepatocytes. Methods: The expression of hepatocyte markers and CYP3A family genes (CYP3A89, CYP3A93, CYP3A94, CYP3A95, CYP3A96, and CYP3A97) were assessed in different organ tissues of the horse and fetal horse liver-derived cells (FHLCs) using quantitative reverse transcription polymerase chain reaction. To elucidate the antioxidant effects of MSM on FHLCs, cell viability, levels of oxidative markers, and gene expression of CYP3A were investigated in H2O2-induced oxidative stress in the presence and absence of MSM. Results: FHLCs exhibited features of liver cells and simultaneously maintained the typical genetic characteristics of normal liver tissue; however, the expression profiles of some liver markers and CYP3A genes, except that of CYP3A93, were different. The expression of CYP3A93 specifically increased after the addition of H2O2 to the culture medium. MSM treatment reduced oxidative stress as well as the expression of CYP3A93 and heme oxygenase 1, an oxidative marker in FHLCs. Conclusion: MSM could reduce oxidative stress and hepatotoxicity in FHLCs by altering CYP3A93 expression and related signaling pathways.

• Journal of the Korean Chemical Society
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• v.36 no.1
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• pp.147-156
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• 1992

Supported lead oxide catalysts were prepared by using ${\alpha}-,{\beta}-{\gamma}$-alumina, and MgO as a support. Among the supported lead oxide catalysts, MgO-supported catalyst showed the highest $C_2^+$ hydrocarbon selectivity for the methane conversion into $C_2^+$ hydrocarbons, but ${\gamma}$-alumina-supported PbO catalyst gave the highest $CO_2$ selectivity. And ${\alpha}$-alumina-supported catlyst showed the midium activity, whereas ${\beta}$-alumina-supported catalyst gave little activity. These reaction characteristics seemed to be largely dependent on the acticity of lattice oxygens in supported catalysts, which would be influnto be largely dependent on the activity of lattice oxygens in supported catalysts, which would be influenced in the interaction between the supports and lead oxides and the properties of supports. Especially, much higher ration of (002)/(111) peak intensities for PbO phase on MgO support than on the other supports in X-ray diffraction analysis was considered to be ab evidence that methane oxidative coupling of methane might be so-called structure-sensitive reaction, and this seemed to be an example of surface oxide-support interaction (SOSI) in the oxidative coupling reaction.