• Journal of the Korean Electrochemical Society
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• v.10 no.3
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• pp.159-168
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• 2007

An electrochemical study related to the redox characteristics of Ethyl-3-acetyl-6-methyl-1, 4-diphenyl-4, 3a-dihydro-1, 3, 4-triazolino[3, 4-a] pyrimidine-5-carboxylate ester and its derivatives (1a-f) and (2a-e) in nonaqueous solvents such as 1, 2-dichloroethane (DCE), dichloromethane (DCM), acetonitrile (AN), dimethylsulphoxide (DMSO) and tetrahydrofurane (THF) using $0.1\;mol\;dm^{-3}$ tetrabutylammonium perchlorate (TBAP) as a supporting electrolyte at platinum, glassy carbon and gold electrodes, has been performed using cyclic voltammetry (CV). Controlled potential electrolysis (CPE) is also carried out to elucidate the course of different electrochemical reactions through the separation and identification of the intermediates and final electrolysis products. The redox mechanism is suggested and proved. It was found that all the investigated compounds in all solvents are oxidized in a single irreversible one electron donating process following the well known pattern of the EC-mechanism to give a dimer. On the other hand, these compounds are reduced in a single irreversible one electron step to form the anion radical, which is basic enough to proton from the media forming the radical which undergoes tautomerization and then dimerization processes to give also another bis-compound through N-N linkage formation.

• YAKHAK HOEJI
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• v.49 no.4
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• pp.347-354
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• 2005

Lipopolysaccharide (LPS) induces synthesis of several inflammatory cytokines and nitric oxide (NO). NO in brain is involved not only in the regulation of important metabolic pathways via intracellular cyclic GMP-dependent path­ways, but also in neurotoxic damage by reacting with superoxide ion leading to form peroxynitrite radical. Oxidative stress has suggested to be related to the inhibition of NO synthase/cyclic GMP pathway. OQ21 is a new fluorinated quinone compound that is recently known to have inhibitory effects on both NO synthase (NOS) and guanylyl cyclase (GC). In this study, we examined effects of OQ21, other known NOS or GC inhibitors, or an antioxidant, melatonin, on the oxidative stress produced by LPS in rat brain. Oxidative stress was observed by using the 2',7'-dichlorofluorescin diacetate to measure intra-cellular reactive oxygen species (ROS) production and by measuring the formation of thiobarbituric acid reactive substances to measure lipid peroxidation. LPS induced significant increase in both ROS produdction and lipid peroxidation in all brain regions tested (striatum, hippocampus and cortex), which were dissected 6hr after intraperitoneal administration of LPS to rats. Direct striatal injection of two NOS inhibitors, N-nitro-L-arginine methyl ester and diphenyleneiodonium, or a GC inhibitor, IH-[1,2,4]oxadiazolo[4,3-a]quinoxaline-l-one, produced no significant ROS increase. However, OQ21 enhanced ROS formation in striatal tissues from LPS-treated rats. Melatonin decreased LPS-induced ROS formation and decreased ROS formation increased by OQ21 in striatum of LPS-treated rats.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.252-257
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• 2023

In this study, to replace phthalate-based plasticizers known as endocrine disruptors, compounds as plasticizer candidates were synthesized by using alcohols containing rings and fatty acids extracted from animal and vegetable oils, and their properties as plasticizers, including their plasticization efficiency, were evaluated. Nine compounds synthesized by esterification of fatty acids (caprylic acid, capric acid, lauric acid) and alcohols (solketal, benzyl alcohol, cyclohexanol) were identified by ¹H-NMR. The nine synthetic compounds were evaluated for their plasticity by adding them to PVC resin, and compared with the commercial plasticizers DEHP, DINCH, and ESO. According to the results, plasticization efficiency was 0.96 to 1.02 times higher than DEHP, 0.94 to 0.98 times higher than ESO, and 1.05 to 1.10 times higher than DINCH. Thermal stability was somewhat lower than that of DEHP and DINCH, but showed better results than ESO. The results of the solvent extraction test showed that both aqueous and oily solvents showed higher values than DEHP and DINCH but showed similar or superior properties to ESO.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.3
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• pp.332-341
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• 2007

The purpose of this study was to investigate the change of flavor compounds of freeze-dried garlic and garlic roasted with soybean oil and sesame oil. Freeze-dried garlic and ground raw garlic roasted with oils was prepared at $180^{\circ}C$ for 5 minutes. Volatile compounds of garlic samples were obtained by Likens-Nickerson distillation/solvent extraction and identified by GC and GC/MS. Sulfur compounds, methyl allyl sulfide, diallyl sulfide, methyl allyl disulfide, dimethyl trisulfide, diallyl disulfide, methyl allyl trisulfide and diallyl trisulfide were the major volatile in garlic flavor which was more than 98% of the total volatile compounds. The total amount of sulfur compounds in freeze-dried garlic roasted with soybean oil was decreased to 20% compare to that of garlic flavor; however, 10 pyrazines such as 2-methyl pyrazine, 2,6-dimethyl pyrazine, 2-ethyl-5-methyl pyrazin and 3-ethyl-2,5-dimethyl pyrazine which were not originated from both freeze-dried garlic and soybean oil were identified. They might be generated from thermal interactions of sugars and nonvolatile flavor precursors of garlic. In freeze-dried garlic roasted with sesame oil, the amount of diallyl sulfide, methyl allyl disulfide, dimethyl trisulfide increased whereas diallyl disulfide completely disappeared. The amount of two cyclic compounds 3,4-dihydro-3-vinyl-1,2-dithiin and 2-vinyl-4H-1,3-dithiin, which were artifacts from allicin, increased in roasted garlic with sesame oil.

• Microbiology and Biotechnology Letters
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• v.35 no.1
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• pp.26-29
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• 2007

Tautomycetin (TMC), which is produced by Streptomyces sp. CK4412, is a novel activated T cell-specific immunosuppressive compound with an ester bond linkage between a terminal cyclic anhydride moiety and a linear polyketide chain bearing an unusual terminal alkene. Antifungal activity against Aspergillus niger and TMC productivity assayed by HPLC using culture extracts from Streptomyces sp. CK4412 grown on solid medium adjusted at various pH were measured. The cells cultured at acidic pH (pH 4-5) medium exhibited much stronger antifungal activity as well as higher TMC productivity than those cultured at neutral pH medium, implying that the acidic pH-shock should be an efficient strategy to induce the productivity of secondary metabolites in Streptomyces culture.