• YAKHAK HOEJI
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• v.50 no.1
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• pp.47-51
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• 2006

The roots of Dipsacus asper are used in traditional Chinese medicine as an analgesic, enhancement of liver activity, an anti-inflammatory agent and the treatment of fractures. In order to investigate the antioxidative activity, Dipsaci Radix was extracted with MeOH and fractionated with $CHCl_3$, EtOAc, BuOH and water. MeOH ex. and its solvent fractions were determined on the free radical scavenging activity by DPPH method and antioxidative activity on low density lipoprotein oxidation. The EtOAc and BuOH fractions showed antioxidative activities and from their fractions, two compounds were isolated and identified as hederagenin 3-O-${alpha}$-L-arabino pyranoside (compound 1) and O-${\alpha}$-L-arabinopyranosyl hed-eragenin 28-O-${\beta}$-D-glucopyranosyl ($1{\to}6$)-${\beta}$-D-glucopyranosyl ester (compound 2). Saponin glycoside, compound I showed anti-oxidative activity.

• Archives of Pharmacal Research
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• v.13 no.3
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• pp.252-256
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• 1990

Oxidative damage to DNA can be caused by excited oxygen species, which are produced by radiation or are by-products of aerobic metabolism. Endogenous evels of 8-hydroxy-2'deoxyguanosine (8-OH-dG), an adduct that results from the damage of DNA caused by hydroxyl radical,have been detected in E. coli and S. typhimurium. Treatment of bacterial cells with various concentrations of hydrogen peroxide caused a moderate increase in the 8-OH-dG content. The enzymatic release of 8-OH-dG from asocorbate/Cu(II)-treated DNA was effected by an extract of E. coli cells. These results indicate that 8-OH-dG is formed in vivo inbacterial DNA through endogenous oxidative mechanisms and on treatment with an oxygen radical-producing agent and that it is repairable.

• Journal of Korean Society of Water and Wastewater
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• v.31 no.6
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• pp.611-618
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• 2017

Recently, applications of high voltage impulse (hereafter HVI) technique to desalting, sludge solubilization and disinfection have gained great attention. However, information on how the operating condition of HVI changes the water qualities, particularly production of hydroxyl radical (${\cdot}OH$) is not sufficient yet. The aim of this study is to investigate the effect of operating conditions of the HVI on the generation of hydroxyl radical. Indirect quantification of hydroxyl radical using RNO which react with hydroxyl radical was used. The higher HVI voltage applied up to 15 kV, the more RNO decreased. However, 5 kV was not enough to produce hydroxyl radical, indicating there might be an critical voltage triggering hydroxyl radical generation. The concentration of RNO under the condition of high conductivity decreased more than those of the low conductivities. Moreover, the higher the air supplies to the HVI reactor, the greater RNO decreased. The conditions with high conductivity and/or air supply might encourage the corona discharge on the electrode surfaces, which can produce the hydroxyl radical more easily. The pH and conductivity of the sample water changed little during the course of HVI induction.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1998.11a
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• pp.182-182
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• 1998

The root of Aralia continentalis Kitagawa(Araliaceae) have been used as an analgesic and fever remedy, and for treatment of rheumatism in Chinese medicine, whereas the young leaves are used for salad. An antioxidant activity of the young leaves of A continentalis was determined by measuring lipid peroxide produced when a mouse liver homogenate was exposed to the air at 37$^{\circ}C$, using 2-thiobarbituric acid(TBA) and by evaluation the radical scavenging activity on 1,l-diphenyl-2 picrylhydrazyl (DPPH) radical. Bioassay guided fractionation of MeOH extract isolated six flavonoid compounds as active components from EtOAc fraction. Adenosine and two saponins were isolated from the weak active BuOH fraction. The antioxidant effect by DPPH radical scavenging activity showed that quercetin was the most active among these compounds. Hyperoside and kaempferol were also active, while 6"-O-acetyl astragalin, astragalin, trifolin, adenosine, oleanolic acid 28-O-glucosyl ester and salsoloside C methyl ester were almost inactive. All the compounds were identified by spectroscopic methods.

• Archives of Pharmacal Research
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• v.25 no.4
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• pp.449-452
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• 2002

The antioxidant activity of Juniperus chinensis (Cupressaceae) was determined by measuring the radical scavenging effect on DPPH (1,1-diphenyl-2-picrylhydrazyl). The methanolic extract of J. chinensis heartwood showed the strong antioxidant activity. The antioxidant activity of n-BuOH soluble fraction was stronger than that of the others, and the fraction was subjected to purification by repeated silica gel and Sephadex LH-20 column chromatography. Quercetin, naringenin, taxifolin, aromadendrin and isoquercitrin were isolated from the n-BuOH fraction. Their structures were elucidated by physico-chemical and spectroscopic studies.

• Food Science and Preservation
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• v.21 no.3
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• pp.421-426
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• 2014

In this study, the antioxidant and pancreatic lipase inhibitory activities of aqueous methanolic (70% methanol) extract from the roots of Anemarrhena asphodeloides were investigated. The extracts of four solvent fractions (the n-hexane layer, EtOAc layer, n-BuOH layer, and $H_2O$ layer) of the 70% methanol extract were also investigated. Furthermore, the total phenolic content was quantified using a spectrophotometric method. All the tested samples showed dose-dependent radical scavenging and pancreatic lipase inhibitory activities. In particular, the pancreatic lipase inhibitory activity of the ethyl acetate soluble portion (the EtOAc layer) from the rhizomes of the A. asphodeloides was higher than that of the other solvent-soluble portions. The antioxidant property of the extracts was evaluated using radical scavenging assays with DPPH and $ABTS^+$ radicals. 1000 mg/ml of the n-BuOH layer extract showed 91.2% DPPH radical scavenging activity. The EtOAc layer extract and the n-BuOH layer extract showed $IC_{50}=20.5{\pm}1.7mg/ml$ and $IC_{50}=50.5{\pm}0.7mg/ml$ $ABTS^+$ radical scavenging activities, respectively. The anti-obesity efficacy of the A. asphodeloides extract was tested via porcine pancreatic lipase assay. A pancreatic lipase inhibitory activity ($IC_{50}$) of $31.3{\pm}0.1mg/ml$ was obtained from the EtOAc layer extract. These results suggest that A. asphodeloides can be considered a new potential source of natural antioxidant and anti-obesity agents.

• Journal of Life Science
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• v.23 no.3
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• pp.361-367
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• 2013

Hizikia fusiformis has been widely used in Oriental herbal medicine and health food. To identify antioxidation properties that contain natural bioactive substances, we investigated the distribution of active compounds existing in batches of organic solvent fractionation. A dried form of H. fusiformis was subjected to sequential fractionation using n-hexane, ethyl acetate, n-BuOH, and aqueous n-BuOH. The results showed that among the four isolated fractions, the n-BuOH fraction showed the highest antioxidation activities. The n-BuOH fraction was applied to reserve-phase silica gel column chromatography, which produced three fractions: BA, BB, and BC. Among these fractions, BB showed the highest antioxidation activities, which increased in a concentration-dependent manner. At a concentration of 1.0 mg/ml n-BuOH fraction, the activities of DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging and reducing power were approximately $45{\pm}0.14%$ and $1.34{\pm}0.23$, respectively. In addition, the activities of ${\beta}$-carotene-linoleic acid, hydrogen peroxide scavenging, and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) radical scavenging were $76{\pm}0.12%$, $82{\pm}0.06%$, and $65{\pm}0.17%$, respectively. These findings suggest that the BB fraction contains potent antioxidation properties and that it could be used in the production of natural and functional foods.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.65-70
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• 2001

OH radical and NOx have been measured in a methane-air partially premixed flame using PLIF technique to define preheated air combustion characteristics. The temperature of mixture is determined by 300K, 400K, 600K and 800K below the auto-ignition temperature respectively. Flame height increases as equivalence ratio increased. As initial enthalpy is supplied, the radius of flame was increased and much amount of yellow flame in rich equivalence ratio was observed. This is due to the faster burning velocity. Also initial oxidization begins earlier as the initial temperature of mixture increased. It means that height of premixed flame front decreased. This phenomenon can be observed OH PLIF image. The qualitative analysis of OH concentration in the PLIF image shows that overall OH concentration increases with equivalence ratio and the initial temperature of mixture increased. At the preheating temperature goes up, axial gradient of OH concentration is less steep than that of lower temperature condition. This may identify that combustion reacts continuously, so preheated air combustion can evade the local heating and make high temperature indiscriminately in the overall reaction zone.

• Journal of Soil and Groundwater Environment
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• v.6 no.1
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• pp.3-12
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• 2001

During ozonation process, the hydroxyl radical generation rates were measured under different experimental conditions (ozone feed rate, nitrobenzene concentration, hydroxyl radical scavenger, pH, HO$_2$O$_2$/O$_3$ etc.) Nitrobenzene could be decomposed by hydroxyl radical rather than ozone only and nitrobenzene decomposition rate was expressed with functions of ozone and nitrobenzene concentration. The rate was decreased as the hydroxyl radical scavenger concentration was increased, and all results were followed pseudo first-order reaction. Using a competitive method, hydroxyl radical generation rate was measured with probe compound and scavenger. It was proportional to ozone concentration, and 0.24mo1 of hydroxyl radical was produced with 1mol of ozone. Under different pH conditions, hydroxyl radical generation rates were measured (pH 10.2 (0.91Ms$^{-1}$ ) > pH 7.3 (0.72Ms$^{-1}$ ) > pH 5.6 (0.67Ms$^{-1}$ ) > pH 3.4 (0.63Ms$^{-1}$ )) showing higher generation rate at high pH values. Addition of hydrogen peroxide promoted the generation rate of hydroxyl radical. Considering the results of pH experiments and addition of hydrogen peroxide experiments, the hydroxyl radical generation rate was 1.6 times higher in hydrogen peroxide solution than in high pH solution, indicating addition of hydrogen peroxide is better promoter to produce the hydroxyl radical in ozonation. These results could be applied to AOPs to remediate the contaminated wastewater and groundwater.

• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.177-179
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• 2012

This work presents an experimental investigation to study $NO_x$ emissions under stoichiometric air ratio and elevated pressure (2~10bar) in a High Press Combustor(HPC) equiped with double cone burner which was designed by Pusan Clean Coal Center(PC3). Exaust gas temperature and $NO_x$ emissions were measured at the end of the combustion chamber. The $OH^*$ radical concentration and $NO_x$ emission were decreased as a function of increasing ${\lambda}$ generally. On the other hand, $OH^*$ radical concentration and $NO_x$ emission increased with ${\lambda}$ pressure of the combustion chamber. $NO_x$ emissions which were governed by thermal $NO_x$, were highly increased under the elevated pressure, but slightly increased at sufficiently low fuel concentrations (${\lambda}>2.0$).