• Bulletin of the Korean Chemical Society
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• 제25권12호
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• pp.1907-1910
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• 2004

Generation of hydroxyl radical, one of their major active species in ozonation of water was directly observed with spin-trapping/electron spin resonance (ESR) technique using 5,5-dimethyl-pyrrolidine-1-oxyl (DMPO) as a spin-trapping reagent. Hydroxyl radical was trapped with DMPO as a stable radical, DMPO-OH. 80 mM of ozone produced $1.08{\times}10^{-6}$M of DMPO-OH, indicating that 1.4% of ${\cdot}$OH is trapped with DMPO if ${\cdot}$OH is produced stoichiometrically from ozone. Humic acid suppressed DMPO-OH generation in a dose-dependent manner. Generation rate of DMPO-OH was determined with ESR/stopped-flow measurement. Phenol derivatives increased the amount and generation rate of DMPO-OH, indicating that phenol derivatives enhance·OH generation during ozonation of water.

• 한국자원식물학회지
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• 제21권4호
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• pp.254-259
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• 2008

약용식물 9종의 물 추출물에 대한 항산화 효과를 탐색하기 위해 in vitro 조건에서 강력한 산화력과 독성을 갖는 $ONOO^-$와 ${\cdot}$OH radical의 소거효과를 측정하였다. 그 결과, 감잎, 구기자, 꾸지뽕나무, 담쟁이덩굴, 마디풀, 비파나무, 으름덩굴, 참취 추출물은 10${\mu}g/ml$ 농도에서 50% 이상의$ONOO^$ 소거효과를 나타냈다. 이러한 $ONOO^-$ 소거효과는 양성 대조물인 penicillamine(94.08${\pm}$3.04)에 비해 낮았지만 비파나무 물 추출물(89.87${\pm}$4.57)이 다른 시료에 비해 가장 강력한 $ONOO^-$ 소거효과를 나타냈다. 또한, 가는잎쐐기풀과 감잎 물 추출물은 1mg/ml 농도에서 양성대조물인 thiourea 보다 효과적인${\cdot}$OH radical 억제효 과를 나타냈다. 결론적으로 9종의 약용식물은 $ONOO^-$와${\cdot}$OH radical과 연관된 산화적 스트레스에 의한 세포와 조직의 손상을 억제시킬 수 있는 천연 항산화제로 밝혀졌다.

• Bulletin of the Korean Chemical Society
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• 제27권11호
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• pp.1785-1790
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• 2006

A novel kinetic method for determination of $HO_2{^{\cdot}}/O_2{^{{\cdot}-}}$ in ozone decomposition in water is described. In this study, potential interferences of $O_3$ and the hydroxyl radicals, $^{\cdot}OH_{(O3)}$, are suppressed by $HSO_3{^-}/SO_3{^{2-}}$. $HO_2{^{\cdot}}/O_2{^{{\cdot}-}}$ formed in ozone decomposition reduces $Fe^{3+}$-EDTA into $Fe^{2+}$-EDTA and subsequently the well-known Fenton-like (FL) reaction of $H_2O_2$ and $Fe^{2+}$-EDTA produces the hydroxyl radicals, $^{\cdot}OH_{(FL)}$. Benzoic acid (BA) scavenges $^{\cdot}OH_{(FL)}$ to produce OHBA, which are analyzed by fluorescence detection (${\lambda}_{ex}=320nm$ and ${\lambda}_{ex}=400nm$). The concentration of $HO_2{^{\cdot}}/O_2{^{{\cdot}-}}$ in ozone decomposition has been determined by the novel kinetic method using the experimentally determined half-life ($t_{1/2}$). The steady-state concentration of $HO_2{^{\cdot}}/O_2{^{{\cdot}-}}$ is proportional to the $O_3$ concentration at a given pH. However, the steady-state concentration of $HO_2{^{\cdot}}/O_2{^{{\cdot}-}}$ in ozone decomposition is inversely proportional to pH values. This pH dependence is due to significant loss of $O_2{^{{\cdot}-}}$ by $O_3$ at higher pH conditions. The steady-state concentrations of $HO_2{^{\cdot}}/O_2{^{{\cdot}-}}$ are in the range of $2.49({\pm}0.10){\times}10^{-9}M(pH=4.17){\sim}3.01({\pm}0.07){\times}10^{-10}M(pH=7.59)$ at $[O_3]_o=60{\mu}M$.

• 상하수도학회지
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• 제31권6호
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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.

• Journal of Applied Biological Chemistry
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• 제50권3호
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• pp.115-119
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• 2007

To discover the sources with antioxidant and tyrosinase inhibitory activities in Korean traditional medicines, 10 extract of medicinal plants were screened for their potential to scavenge stable 1,1-diphenyl-2-picryhydrazyl (DPPH) free radical, inhibit hydroxyl radical (${\cdot}OH$), total phenolic content, and inhibition of tyrosinase. The potency of DPPH radical scavenging activity was shown in the extract of Ulmus davidiana var. japonica Nakai that has a greater effect with $IC_{50}$ values of $6.49{\pm}5.43{\mu}g/mL$, than BHA ($IC_{50}=20.99{\pm}0.74{\mu}g/mL$), L-ascorbic acid $(IC_{50}=20.59{\pm}1.06{\mu}g/mL),\;and\;{\alpha}-tocopherol\;(IC_{50}=25.55{\pm}0.26{\mu}g/mL)$ as a positive control. The ${\cdot}OH$ scavenging activities were observed in the plants tested. Acanthopanax senticosus, Cirsium setiders, U. davidiana exhibited scavenging activity of more than 60% at $500{\mu}g/mL$. The scavenging activity(%) of BHA and a-tocopherol were 64.32 and 55.87% at $500{\mu}g/mL$, respectively. The total phenolic content was determined, in order to assess its effect on the extract's antioxidant activity. The total phenoic content of $33.37{\pm}0.52mg/g$ was conformed by methanolic extract of U. davidiana. The U. davidiana and Morus bombycis exhibited tyrosinase inhibitory activity with a $34.28{\pm}1.32\;and\;75.57{\pm}1.10%$, respectively. In particular, M. bombycis has stronger tyrosinase inhibitory activity than albutin with $36.48{\pm}3.56%$ as a positive control. This work showed that the inhibitory abilities of Korean medicinal plants, such as U. davidiana and M. bombycis, on DPPH free radical, inhibit hydroxyl radical (${\cdot}OH$), and inhibition of tyrosinase and total phenolic content, can be useful in the prevention and treatment of free radical-relate disease. Investigations into further isolation of inhibitory principles of U. davidiana and M. bombycis are now in progress.

• Preventive Nutrition and Food Science
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• 제17권4호
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• pp.261-268
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• 2012

Ribes diacanthum Pall (RDP) is a member of the Saxifragaceae family. The plant is traditionally used in Mongolia for the treatment of various ailments associated with kidney and bladder's diseases, cystitis, kidney stone, and edema. This study was aimed to investigate antioxidant activities of different solvent extracts of whole Pall plants, based on ferric-reducing antioxidant potential (FRAP), 2,2'-azinobis(3-ethybenzothiazoline-6-sulfonic acid) ($ABTS{\cdot}+$) radical scavenging activity, 1,1-diphenyl-2-picrydrazyl ($DPPH{\cdot}$), and hydroxyl (${\cdot}OH$) radical scavenging activities. Additionally, total flavonoids and phenolic contents (TPC) were also determined. The ethyl acetate extract of RDP (EARDP) had a remarkable radical scavenging capacity with an $IC_{50}$ value of 0.1482 mg/mL. In addition, EARDP was shown to be higher in total phenolic and flavonoid contents than the methanol extract of RDP (MRDP). Moreover, the EARDP had the predominant antioxidant capacity, DPPH, hydroxyl, and ABTS radical scavenging activities and ferric reducing power. These results suggest a potential for R. diacanthum Pall extract as a functional medicinal material against free-radical-associated oxidative damage.

• 대한약리학회지
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• 제21권1호
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• pp.34-48
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• 1985

항균제 nitrofurantion에 의한 폐독작용의 생화학적 기전을 규명하기 위한 연구 일환으로 in vitro에서 폐장 microsome 지질의 과산화 및 반응성 산소 radical $(O^{-}_{2}{\cdot},\;H_2O_2,\;OH{\cdot},\;^1O_2)$의 생성에 대한 nitrofurantion의 영향과 양자 간의 상호 관련성을 검토하였다. Nitrofurantion은 호기성 반응 조건에서 돼지 폐장 microsome의 NADPH 의존성 지질 과산화를 용량 의존적으로 증가시킬 뿐 아니라 $O^{-}_{2}{\cdot},\;H_2O_2$ 및 두 radical의 상호 작용으로 2차적으로 형성되는 $OH{\cdot}$의 생성 또한 촉진하였으며 $^1O_2$생성은 관찰되지 않았다. 이와 같은 폐장 microsome지질 과산화 증가는 SOD 및 catalase에 의하여 억제될 뿐만 아니라 $OH{\cdot}$ 제거 물질인 mannitol, thiourea에 의하여도 현저히 억제되었으며, $^1O_2$ 제거 물질에 의하여는 영향을 받지 않았던 한편 염기성 반응 조건에서는 nitrofurantoin에 의한 지질 과산화가 관찰되지 않았다. 이상의 결과로 미루어 보아 nitrofurantoin은 폐장 microsome의 NADPH 의존적이 반응성산소 radical $(O^{-}_{2}{\cdot},\;H_2O_2$ 및 $OH{\cdot})$의 생성을 증가시키며 이들 중 특히 $OH{\cdot}$ 에 의한 microsome막 지질 과산화를 촉진하는 것으로 결론지었고, 이와 같은 in vivo 현상은 nitrofurantion의 in vitro 폐독작용의 기전을 설명하는 일부가 될 것으로 사료하였다.

• Preventive Nutrition and Food Science
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• 제14권1호
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• pp.86-89
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• 2009

In this study, we investigated the free radical [1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radical (${\cdot}OH$) and superoxide anion (${O_2}^-$)] scavenging activity of MeOH extract and 3 fractions of Citrus junos. Of the tested fractions, the BuOH fraction showed the strongest DPPH scavenging activity, showing the $IC_{50}$ values of 63.4 mg/mL. Therefore, we continuously carried out DPPH, ${\cdot}OH$ and ${O_2}^-$ scavenging activity tests of BuOH fraction of Citrus junos. The BuOH fraction of Citrus junos inhibited DPPH radical to 97.5% at a concentration of 1000 mg/mL and the scavenging activities were increased concentration-dependently. In addition, BuOH fraction from Citrus junos also scavenged ${\cdot}OH$ in a concentration dependent manner from 5 to 1000 mg/mL. Furthermore, BuOH fraction showed about 56% ${O_2}^-$-scavengimg activity at 25 mg/mL concentration but, the scavenging activities were not enhanced in a dose dependent manner. The present results suggest that BuOH fraction of Citrus junos would have the protective potential from oxidative stress induced by free radicals.

• BMB Reports
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• 제31권5호
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• pp.492-497
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• 1998

Cu,Zn-superoxide dismutase (SOD) was purified from horseradish by using Mono Q and Superose 12 FPLC column chromatography. The native molecular mass of the purified enzyme was approximately 33 kDa, as determined by gel filtration. The subunit molecular weight, as estimated by SDS-PAGE, was 16 kDa. These results indicated that the native enzyme is a homodimer. We investigated the free radical-generating function of horseradish Cu,Zn-SOD by using a chromogen, 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonate) (ABTS) which reacts with ${\cdot}OH$ radicals to form $ABTS^{+{\cdot}}$ The formation of $ABTS^{+{\cdot}}$ was required for both active Cu, Zn-SOD and $H_2O_2$. The optimal pH for the free radical-generating activity of this enzyme was 6.0-8.0, and it retained about $40^{\circ}C$ of its maximum activity when exposed at $40^{\circ}C$ for 15 min. A neutral scavenger, ethanol, inhibited the $ABTS^{+{\cdot}}$ formation by horseradish Cu, Zn-SOD more effectively than that by the mammalian enzyme. These results suggest that the active channel of horseradish enzyme is slightly larger than that of the mammalian enzyme.

• 농업과학연구
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• 제39권4호
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• pp.511-514
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• 2012

In this study, the comparison of antioxidative effect of the methanol (MeOH) extracts from grains were investigated in vitro radical scavenging system. Ten grains (black rice, rice, barley, wheat, millet, sorghum, glutinous millet, buckwheat, phellines linteus rice and brown rice) were extracted with MeOH. Among the MeOH extracts of grains, sorghum and black rice showed effective scavenging activities of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. The $IC_{50}$ values of sorghum and black rice were $47.4{\mu}g/mL$ and $50.6{\mu}g/mL$, respectively. In addition, black rice also exerted the strongest activities on hydroxyl radical (${\cdot}OH$) scavenging activity. Furthermore, the MeOH extracts of black rice showed effective and dose dependant scavenging activities of DPPH radical and ${\cdot}OH$. These results indicated that black rice showed strong free radical scavenging activity. It suggested that black rice could be a promising natural antioxidant against free radical-induced oxidative damage.