• Environmental Engineering Research
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• 제17권4호
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• pp.205-210
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• 2012

Hydroperoxyl radical/superoxide anion radical ($HO_2{\cdot}/O_2^-{\cdot}$, $pK_a$=4.8) as an intermediate is of considerable importance in oxidation processes. Hence, the method of detecting $HO_2{\cdot}/O_2^-{\cdot}$ with high sensitivity is necessary to be developed. To achieve this objective, this study newly employed terephthalate (TA) as a probe for the measurement of $HO_2{\cdot}/O_2^-{\cdot}$ in the kinetic method presented in our previous study. This method was based on the hydroxylation of TA to produce mainly hydroxyterephthalic acid or hydroxyterephthalate (OHTA), which was analyzed by fluorescence detection (${\lambda}_{ex}$=315nm, ${\lambda}_{ex}$=425nm). The life-time of $HO_2{\cdot}/O_2^-{\cdot}$ and its concentration formed from the photolysis technique of $H_2O_2$ were reported in this study. At range of pH 2-10, the life-time of $HO_2{\cdot}/O_2^-{\cdot}$ was 51-422 sec. In particular, an increase in the life-time with pH was observed. The sensitivities of the kinetic method by using TA were always higher with 1.7-2.5 times at pH 8.0 than those by using benzoic acid. From these results, this study can contribute to understanding the basic functions of $HO_2{\cdot}/O_2^-{\cdot}$ in oxidation processes.

• Bulletin of the Korean Chemical Society
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• 제15권6호
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• pp.465-468
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• 1994

The charge transfer compounds $(TTF)_4FeCl_3{\cdot}CH_3OH,\;(TTF)_4SbCl_4\;and\;(TTF)_5(SbBr_4)_2{\cdot}CH_3COCH_3$ were prepared from reactions of the TTF (tetrathiafulvalene) and metal halides. The compounds were characterized by spectroscopic (UV,IR, EPR and XPS) methods, magnetic susceptibility and electrical conductivity measurements. The d.c electrical conductivities of the pressed pellets are in the order of $10^{-1}-10^{-3} Scm^{-1}$, which lies in the range of semiconductor region at room temperature. It means that the partially ionized TTF has stacked in low-dimensional chain in each compound. Spectroscopic properties also indicate that TTF molecules are partially ionized and charge transfer has occurred from (TTF)n to Fe(III) center in $(TTF)_4FeCl_3{\cdot}CH_3OH$ whereas to the $-SbX_4^-$ entity in $(TTF)_4SbCl_4\;and\;(TTF)_5(SbBr_4)_2{\cdot}CH_3COCH_3$. The EPR g values are consistent with TTF radical formation and EPR linewidths suggest the delocalization of unpaired electrons along TTF stacks. A signal arised from metal (Fe and Sb) ions were not detected in EPR spectra, indicating that metal ion is in the diamagnetic state in each compound. The diamagnetic state was also examined by the magnetic susceptibility measurement. The magnetic properties reveal the significant interaction between the $TTF^+$ radical cations in the stacks. The oxidation state of metal ions was also investigated by XPS spectra.

• 혜화의학회지
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• 제25권1호
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• pp.145-153
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• 2016

Objectives : The purpose of this study is to evaluate the wound healing potential of Glycyrrhiza uralensis extract. Methods : Free radical scavenging activity tests for DPPH, peroxynitrite (ONOO) and hydroxyl radical (${\cdot}OH$) and total phenolic contents of Glycyrrhiza uralensis extract were conducted. Tube formation assay was performed using human umbilical vein endothelial cells (HUVECs). Results : The results showed that Glycyrrhiza uralensis extract exerted inhibitory effects on ONOO and ${\cdot}OH$. Tube formation in HUVEC was increase in a dose dependent manner. Conclusions : These results show the potential to promote the wound healing process by Glycyrrhiza uralensis extract.

• 원예과학기술지
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• 제29권1호
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• pp.68-73
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• 2011

본 연구는 차로써 이용이 증대되고 있는 구절초 꽃의 항산화 능력과 이와 관련된 유효한 성분을 탐색하고자 수행되었다. 구절초 꽃을 MeOH로 추출한 수율은 16%였고, MeOH 추출물을 다시 용매별로 분획한 결과 잔류 water > n-hexane > EtOAc > n-BuOH > $CHCl_3$ 분획물 순으로 추출수율을 보였다. 총 polyphenol 함량은 EtOAc분획물이 $195mg{\cdot}g^{-1}$으로 가장 높았고 그 다음으로 MeOH 추출물, $CHCl_3$, 잔류 water, n-BuOH, n-hexane 분획물 순으로 높게 나왔다. Flavonoid 함량 역시 EtOAc 분획물이 $143mg{\cdot}g^{-1}$으로 가장 높게 나타났으며 그 다음으로는 n-BuOH, n-hexane, 메탄올, 잔류 water, $CHCl_3$ 분획물 순으로 높았다. 구절초의 전자공여능과 총 항산화력 측정에서는 추출물의 농도가 높아질수록 활성이 증가하였으며 EtOAc 분획물이 $100{\mu}g{\cdot}mL^{-1}$에서 81.56%, 68.12%의 가장 높은 전자공여능 및 총 항산화력을 나타내었다. 구절초 MeOH 추출물과 EtOAc분획물을 HPLC로 분석한 결과 flavonoid 유효성분으로 quercetin과 luteolin이 확인되었으며 EtOAc 분획물 경우 각각의 함량이 $20.02mg{\cdot}g^{-1}$, $1.65mg{\cdot}g^{-1}$이었다. 이상의 결과를 종합해볼 때, 구절초 꽃의 항산화력은 MeOH 추출물의 EtOAc 분획에 포함된 quercetin에 주로 기인하는 것으로 판단되었다.

• Nutrition Research and Practice
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• 제13권4호
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• pp.279-285
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• 2019

BACKGROUND/OBJECTIVES: Excessive production of reactive oxygen species (ROS) such as hydroxyl (${\cdot}OH$), nitric oxide (NO), and hydrogen peroxide ($H_2O_2$) is reported to induce oxidative stress. ROS generated by oxidative stress can potentially damage glial cells in the nervous system. Cordyceps militaris (CM), a kind of natural herb widely found in East Asia. In this study, we investigated the free radical scavenging activity of the CM extract and its neuroprotective effects in $H_2O_2$-induced C6 glial cells. MATERIALS/METHODS: The ethanol extract of CM ($100-1,000{\mu}g/mL$) was used to measure DPPH, ${\cdot}OH$, and NO radical scavenging activities. In addition, hydrogen peroxide ($H_2O_2$)-induced C6 glial cells were treated with CM at $0.5-2.5{\mu}g/mL$ for measurement of cell viability, ROS production, and protein expression resulting from oxidative stress. RESULTS: The CM extract showed high scavenging activities against DPPH, ${\cdot}OH$, and NO radicals at concentration of $1,000{\mu}g/mL$. Treatment of CM with $H_2O_2$-induced oxidative stress in C6 glial cells significantly increased cell viability, and decreased ROS production. Cyclooxygenase-2 and inducible nitric oxide synthase protein expression was down-regulated in CM-treated groups. In addition, the protein expression level of phospho-p38 mitogen-activated protein kinase (p-p38 MAPK), phospho-c-Jun N-terminal kinase (p-JNK), and phospho-extracellular regulated protein kinases (p-ERK) in $H_2O_2$-induced C6 glial cells was down-regulated upon CM administration. CONCLUSION: CM exhibited radical scavenging activity and protective effect against $H_2O_2$ as indicated by the increased cell viability, decreased ROS production, down-regulation of inflammation-related proteins as well as p-p38, p-JNK, and p-ERK protein levels. Therefore, we suggest that CM could play the protective role from oxidative stress in glial cells.

• Korean Chemical Engineering Research
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• 제47권4호
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• pp.441-445
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• 2009

고분자전해질 막의 전기화학적 열화에 미치는 온도의 영향에 대해 연구하였다. 가속 열화 조건(OCV, anode 무가습, cathode 65% RH)에서 셀 온도를 변화시켜 144시간 운전한 후 셀 성능은 12에서 35%까지 감소하였다. 이러한 성능 감소는 FER(Fluoride Emission Rate) 측정에서 알 수 있듯이 과산화수소 혹은 산소라디칼(${\cdot}OH$, $HO_2{\cdot}$)의 공격에 의한 막의 열화에 따른 것으로 라디칼 형성을 위한 가스 crossover의 증가를 가져왔다. 전극에서의 라디칼 생성은 ESR로 확인하였다. 고분자막 열화의 온도 의존성을 나타내는 Arrhenius plot에 얻어진 활성화 에너지 값은 66.2 kJ/mol이었다. 셀 작동온도 증가는 라디칼 형성속도와 라디칼이 막을 공격하는 반응 속도뿐 아니라 가스 crossover 속도도 증가시켜 막 열화를 가속화시켰다.

• 생물환경조절학회지
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• 제18권1호
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• pp.60-66
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• 2009

나물로 이용되는 방아풀, 쑥부쟁이 및 씀바귀의 효율적인 건조방법을 구명하고자 건조방법을 달리하여 건조한 후 메탄올을 용매로 한 추출액 $1,000mg{\cdot}L^{-1}$ 생리활성을 조사하였다. 총 페놀 함량은 방아풀과 쑥부쟁이는 동결건조 한 것에서 각각 65.1 및 $60.2mg{\cdot}L^{-1}$로, 씀바귀는 오븐에서 건조한 것에서 $51.2mg{\cdot}L^{-1}$로 가장 많았다. 총 플라보노이드 함량은 방아풀은 오븐건조 처리구에서 $70.6mg{\cdot}L^{-1}$로, 쑥부쟁이와 씀바귀는 동결건조 처리구에서 각각 53.9 및 $35.8mg{\cdot}L^{-1}$로 가장 많았다. 전자 공여능은 방아물의 경우동결건조 한 것에서 78.8%로 가장 높았으며, 쑥부쟁이는 $89.8{\sim}90.9%$로 유의성을 나타내지 않았다. 씀바귀 추출물의 전자 공여능은 오븐으로 건조한 것(91.9%), 자연건조 한 것(91.0%), 동결건조 한 것(90.9%) 순으로 높았다. 아질산염 소거능은 방아풀과 쑥부쟁이는 자연건조 한 것에서 각각 73.3및 78.2%로 높았으며, 씀바귀는 동결건조 한 것에서 75.1%로 가장 높았다.

• 한국물환경학회지
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• 제22권5호
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• pp.851-855
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• 2006

The aim of this study was to investigate characteristics of formation of mixed oxidants and some aspects of the performance of electrochemical process as an alternative disinfection strategy for water purification. The study of electrochemical process has shown free chlorine to be produced, but smaller amounts of stronger oxidants, such as ozone, hydrogen peroxide and OH radicals, were also generated. The formation of ozone and hydrogen peroxide increased with increasing electric conductivity, but was limited at conductivities greater than 0.6 mS/cm. Also, formation of OH radical was enhanced as electric conductivity was increased to 0.9 mS/cm and The stead-state concentrations of OH radical were calculated at $1.1{\sim}6.4{\times}10^{-14}M$. Using E. coti, inactivation kinetic studies were performed. With the exception of free chlorine, the role of mixed oxidants, especially OH radical, was investigated for enhancement of the inactivation rate.

• 한국해양바이오학회지
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• 제2권3호
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• pp.187-191
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• 2007

The radical scavenging activity of methanol extracts of seaweeds and their active compounds, alginic acid, fucoidan and phloroglucinol, were investigated under in vitro. Among methanol extracts of seaweeds (sea mustard, sea tangle, seaweed papulosa, fusiforme, sea lettuce, purple laver and chlorella), seaweed papulosa and sea tangle showed strong scavenging activities of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and hydroxyl radical (${\cdot}OH$). In addition, under in vitro, the scavenging activities on DPPH radical of alginic acid and fucoidan, which are active compounds of brown algae, and phloroglucinol, the active compound from Ecklonia species, were evaluated and compared. Fucoidan and phloroglucinol showed strong DPPH scavenging effect, in particular, phloroglucinol had strongest activity among the active compounds. On the other hand, alginic acid did not exert DPPH scavenging activity. From the present study, we could confirm the antioxidative activity of seaweeds and its active compounds.

• 생약학회지
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• 제40권1호
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• pp.1-5
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• 2009

The antioxidant and anti-diabetes effects were evaluated by the ethanol extracts from Astragalus membranaceus root classified by years using through DPPH radical scavenging activity, hydroxyl radical (${\cdot}OH$) scavenging activity, total phenolic and flavonoid contents, reducing power activity, $\alpha$-amylase and $\alpha$-glucosidase inhibitory activities. $IC_{50}$ values for DPPH radical scavenging activity of ethanol extract from 6 years old root ($749.25{\mu}g/mL$) was higher than 1 year ($1452.67{\mu}g/mL$) and 3 years old root ($1095.61{\mu}g/mL$). 6 years old root showed better effects in ${\cdot}OH$ scavenging activity ($IC_{50}$: $10.58{\mu}g/mL$), reducing power, total phenolic contents ($26.13{\pm}0.79\;Tan\;{\mu}g/mg$, $24.03{\pm}0.74\;Cat\;{\mu}g/mg$) $\alpha$-amylase ($33.33{\pm}0.55%$) and $\alpha$-glucosidase inhibitory activity ($49.71{\pm}1.01%$). On the other hand, total flavonoid compound contents were estimated much higher in 1 year old root ($44.93{\pm}1.35\;Que\;{\mu}g/mg$, $70.32{\pm}2.03\;Rut\;{\mu}g/mg$) than others. Based on these results, It was suggested that 6 years old root of A. membranaceus has a potential candidate for functional cosmetic and medicine.