• Journal of the Korean Society of Combustion
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• v.4 no.1
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• pp.27-38
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• 1999

We constructed a wire-cylinder type pulsed corona discharge system for $NO_x$ removal, which was operated in room temperature. A emission spectrometer was built with a boxcar averager and monochrometer equipped with photo-multiplier tube detector. The sensitivity of the emission spectrometer was greatly improved by synchronizing the emission spectrometer with pulsed corona discharge system using a triggered spark-gap switch. $N_2$ spectrum($c^3{\Pi}_u{\rightarrow}X^1{\Sigma}_g{^+}$) was measured in the range of 300 - 450 nm and oxidizing OH radical emission($A^2{\Sigma}^+{\rightarrow}X^2{\Pi}$) was measured in case $N_2$ was supplied with water bubbling. As wet gas composition of inlet $N_2$ supplied in the discharge system increased, the intensity of OH emission was increased and saturated at wet gas composition 50%. We also investigated additive effect of $C_2H_4,\;H_2O,\;H_2O_2$ on the intensity of OR emission and $NO/NO_2/NO_x$ reduction and analysed the related reaction mechanism in corona discharge process. $H_2O_2$ additive increased the intensity of OH emission and $NO/NO_x$ reduction.

• Bulletin of the Korean Chemical Society
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• v.8 no.5
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• pp.414-418
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• 1987

Electrochemical reduction of dibenzoylmethane was studied on mercury electrode by means of cyclic voltammetry, polarography and potentiostatic measurements in ethanol-water system. In acidic solutions monomeric pinacol was produced by irreversible two-electron process while monomeric and dimeric pinacol were competitively produced by the same process in neutral solution. However, in basic solution the dimeric pinacol was mostly produced through radical by irreversible one-electron transfer process. Mechanisms of the reduction of dibenzoylmethane are deduced from Tafel slope, pH dependance and reaction order with respect to the concentration of dibenzoylmethane in the solution of various pH.

• Journal of Ginseng Research
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• v.34 no.2
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• pp.145-149
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• 2010

This study investigated the antioxidant effects of ginseng coffee in L6 muscle cells. Ginseng coffee was prepared by coating and digesting coffee beans with ginseng concentrate. The ginseng coffee water extract potently protected against hydrogen peroxide-induced L6 cell death and adenosine triphosphate reduction in a dose-dependent manner; in fact, these cytoprotective effects were significantly greater than those of normal coffee. However, ginseng coffee did not exhibit significant radical scavenging or catalase-like activity. These results suggest that ginseng coffee might act as a cytoprotective agent in muscles, but that the protective effects are not due to a direct radical-reduction property but rather to another intracellular signaling factor.

• 한국연소학회:학술대회논문집
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• 2003.12a
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• pp.209-214
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• 2003

Numerical simulations are performed at atmospheric pressure in order to understand the effect of additives on flame speed, flame temperature, the radical concentration, the NOx formation in freely propagating $CH_4/O_2/N_2$ flames. The additives used are carbon dioxide and hydrogen chloride which have a combination of physical and chemical behavior on hydrocarbon flame. In the flame established with the same mole of methane and additive, $CO_2$ addition significantly contributes toward the reduction of flame speed and flame temperature by the physical effect, whereas addition of HCl mainly does by the chemical effect. The impact of HCl addition on the decrease of the radical concentration is about 1.6-1.8 times as large as $CO_2$ addition. Hydrogen chloride addition is higher on the reduction of EINO than $CO_2$ addition because of the chemical effect of HCl.

• Archives of Pharmacal Research
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• v.29 no.7
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• pp.563-565
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• 2006

Potential anti-Helicobacter pylori agent dehydrodiconiferyl alcohol was synthesized in 44% overall yield, starting from vanillin which could be commercially available. Carbon extension of vanillin followed by the Horner-Wadsworth-Emmons reaction, a biomolecular radical coupling reaction and DIBAL-H reduction gave dehydrodiconiferyl alcohol.

• Advances in Traditional Medicine
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• v.8 no.3
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• pp.260-265
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• 2008

Annona reticulata belonging to the family Annonaceae is traditionally used as anthelmintic and it is reported to have anticancer activity. Free radicals are known to be involved in various types of diseases like cancer, diabetes, neurological disorders etc. The present study was aimed to evaluate free radical scavenging property of methanol extract of the leaves of Annona reticulata in some in vitro models e.g. DPPH, nitric oxide, superoxide and lipid peroxide radical model. The extract showed good dose-dependent free radical scavenging property in all the models. $IC_{50}$ values were found to be 3.22, 170.01, 25.12 and $140.12\;{\mu}g/ml$ respectively in DPPH, nitric oxide, superoxide and lipid peroxidation inhibition assays. Reductive ability of the extract was also tested based on potassium ferricyanide reduction where dose dependant reducing capability was observed. Measurement of total phenolic compounds by Folin-Ciocalteu's phenol reagent indicated that 1mg of the extract contained $146.20\;{\mu}g$ equivalent of pyrocatechol. The findings ascertain promising free radical scavenging property of the extract and the antioxidant property of the extract may be due to the high content of phenolic compounds.

• Advances in Traditional Medicine
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• v.3 no.4
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• pp.205-211
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• 2003

Stem bark of Cinchona sp. (Rubiaceae) is one of the well known drugs for its therapeutic values in traditional as well as modern medicine. Even though a lot of work has been carried out on quinoline alkaloids of Cinchona, its phenolic constituents received very little attention. In the present study, we evaluated antioxidant properties of C. officinalis stem bark methanolic extract and water extract containing phenolic compounds (total phenolics 21.37, 5.18% w/w respectively in the two extracts) in different in vitro and ex vivo models viz., antiradical activity by DPPH reduction, superoxide radical scavenging activity in riboflavin/light/NBT system, nitric oxide radical scavenging activity in sodium nitroprusside/Greiss reagent system and inhibition of lipid peroxidation induced by iron-ADP-ascorbate in liver homogenate and haemolysis of erythrocytes induced by phenylhydrazine in erythrocyte membrane stabilization study. Both the extracts exhibited very good antioxidant activity in all the models tested. The phenolic compounds including tannins present in the stem bark seem to offer protection from the oxidative damage.

• Journal of Oriental Neuropsychiatry
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• v.20 no.1
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• pp.21-42
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• 2009

Objectives : This Study was performed to assess the antioxidant and neuroprotective effect of Chunghyul-dan(Qingxuedan) in PC12 cells and primary rat mesencephalic dopaminergic neurons. Methods : The anioxidant effect was investigated using the DPPH radical and ABTS cation scavenging assays and total polyphenol amout of Chunghyul-dan(Qingxuedan). The neuroprotective effect of Chunghyul-dan(Qingxuedan) in PC12 cells was evaluated using MTT assay. The scavenging activity of Chunghyul-dan(Qingxuedan) on ROS production induced by 6-OHDA(6-hydroxydopamine) in PC12 cells was evaluated, as well as the attenuating effect on GSH reduction. Finally, we examined the neuroprotective effect of Chunghyul-dan(Qingxuedan) against 6-0HDA-induced toxicity in the primary culture of rat mesencephalic doperminergic neurons. Results : Chunghyul-dan(Qingxuedan) showed concentration-dependent scavenging activities in DPPH radical and ABTS cation scavenging assays and it was not cytotoxic to PC12 cells. In postand co-treatment, Chunghyul-dan(Qingxuedan) protected PC12 cells from the 6-OHDA induced toxicity at 50 and 100 ${\mu}$g/mL significantly. And Chunghyu!-dan(Qingxuedan) decreased the 6-OHDA induced ROS production at a dose dependent manner, while increaing the 6-OHDA induced GSH reduction at 50 and 100 ${\mu}$g/mL significantly. Finally, Chunghyul-dan(Qingxuedan) showed signicant protection of rat mescencephalic dopaminergic neurons from 6-OHDA at 1 ${\mu}$g/mL. Conclusions : These results demonstrate that Chunghyul-dan(Qingxuedan) has the antioxidant and neuroprotective effect against 6-0HDA induced cytotoxicity through decreasing ROS production and increasing GSH reduction.

• Journal of the Korean Chemical Society
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• v.33 no.3
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• pp.281-286
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• 1989

The redox properties of benzophydroxamic acid (Hben) and its oxovanadium complex, $VO(Ben)_2$ has been studied by the use of polarograpy and cyclic voltammetry. The radical anions of Hben seem to be generated in acetone. The wave at -0.05V vs. Ag/AgCl electrode might be attributed to the formation of radical anion and the wave at -1.78V vs. Ag/AgCl electrode might be attributed the formation of radical dianion. The $VO(Ben)_2$ exhibits one oxidation wave at + 0.55V and two reduction waves at -0.15V and -1.30V vs. Ag/AgCl electrode; the oxidation is reversible one electron process $(VO(ben)_2 {\rightleftharpoons} VO(ben)^+ + e)$. The reduction wave at -0.15V is quasireversible and is arised from the formation of radical anion,$VO(Ben)_2^-$. The second reduction wave at -1.30V is irreversible and this reduction process produces vanadium(III). This oxygen containing ligand of Hben seems to reduce the stability of + 4 oxidation state of vanadium while the sulfur or nitrogen donor of the ligands stabilize the + 4 oxidation state of vanadium when comparisons are made among several oxovanadium complexes.

• Bulletin of the Korean Chemical Society
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• v.18 no.6
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• pp.604-608
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• 1997

Reactions of arenealdehyde 2-pyridylhydrazones (1) with thianthrene cation radical ($Th^{+·}$) and tris(2,4-dibromophenyl)aminium hexachloroantimonate ($Ar_3N^{+·}SbCl_6^-$) were investigated. The major product was switched depending on the cation radical being used. That is, s-triazolo[4,3-α]pyridines (2), an intramolecular cyclization product, and 1-(2-pyridyl)-1,2,4-triazoles (3), an intermolecular cycloaddition product, were obtained as a major product when reacted with $Th^{+·}$ and $Ar_3N^{+·}$, respectively in nitrile solvents. The plausible mechanisms are proposed based on both the reduction potentials of $Th^{+·}$ and $Ar_3N^{+·}$ and control experiments.