• 대한화학회지
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• 제35권4호
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• pp.405-409
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• 1991

비양성자성용매인 아세토니트릴 중에서 Copper-1-(2-thiazolylazo)-2-naphthol(이하 Cu(II)-TAN으로 줄임) 착물의 전기화학적 성질을 조사하였다. 착물의 직류폴라로그램으로부터 환원전류의 유형과 가역성 및 양성자 주게인 물의 첨가에 따른 영향을 검토하였다. 그리고 환원반응에 관여한 전자수는 일정전위 전기분해법으로 구하였다. 또 일정전위 전기분해한 전해생성물의 UV-Vis Spectrum으로부터 전해생성물을 확인하였다. 이상의 실험 결과로부터 아세토니트릴 용매 중에서 Cu(II)-TAN 착물은 3단계의 환원과정을 거쳐 최종적으로 아민화합물이 됨을 알았다. 이 때 1단계 환원과정에서는 anion radical이 생성되는 과정이고, 2단계 환원과정에서는 dianion이 생성되는 과정이다. 또 1단계와 2단계의 환원과정은 모두 가역성이 좋은 편이었으나 3단계 환원과정은 가역성이 매우 나쁜 편이었다. 또한 각 단계의 환원전류는 확산지배적이었다.

• Natural Product Sciences
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• 제13권3호
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• pp.199-206
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• 2007

Antioxidant activity of 70% aqueous ethanolic extract of leaves of Justicia gendarussa (EJ) was evaluated. EJ was prepared by cold maceration method. The antioxidant potency of EJ was investigated employing various established in vitro systems, such as DPPH radical scavenging, nitric oxide (NO) scavenging, ${\beta}-carotene$ linoleic acid module system (${\beta}$ CLAMS), hydroxyl (OH) radical scavenging, anti lipid peroxidation. $IC_{50}$ values were determined in each experiment. Also, ferric ion reduction capacity of extracts in presence and absence of chelating agent (EDTA) and total antioxidant capacity were determined. Preliminary phytochemical investigation was carried out to know the nature of constituents present in the leaves and correlate it with antioxidant activity. Further total phenolic content was determined in EJ. $IC_{50}$ values of EJ were 123.09 ${\pm}$ 3.01, 643.0 ${\pm}$ 61.10, 132.3 ${\pm}$ 6.03, 68.5 ${\pm}$ 11.5 and 68.13 ${\pm}$ 1.38 ${\mu}g/mL$ in DPPH radical scavenging, NO scavenging, ${\beta}$ CLAMS, OH radical scavenging and anti lipid peroxidation activity respectively. In total antioxidant capacity assay, ascorbic acid equivalent value was found to be 205.56 ${\pm}$ 4.69 ${\mu}g/mg$ of extract. Total phenolic content was found to be 43.76 ${\pm}$ 4.27 ${\mu}g$ equivalent of gallic acid per mg of extract. Phytochemical investigation reveals the presence of flavonoids. The results indicate that EJ possess antioxidant activity and flavonoids are responsible for this activity.

• 대한수학회보
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• 제47권3호
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• pp.653-661
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• 2010

Let R be a ring, and let $\Psi$(R) be the ideal generated by the set {x $\in$R | 1 + sxt $\in$ R is unit-regular for all s, t $\in$ R}. We show that $\Psi$(R) has "radical-like" property. It is proven that $\Psi$(R) has stable range one. Thus, diagonal reduction of matrices over such ideal is reduced.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1993년도 Fifth International Fuzzy Systems Association World Congress 93
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• pp.1106-1108
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• 1993

This paper deals with an industrial application of a fuzzy feedback combined learning control to an industrial batch free radical polymerization reactor. As a result, the plant has reduced the batch reaction time by 50 minute and stabilized both by 40 percent reduction of the standard deviations of product qualities, such as the total solid content and the graft gum, and by 45 percent reduction of the standard deviation of the batch reaction end time.

• Toxicological Research
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• 제17권
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• pp.83-88
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• 2001

Most reactive oxygen species (ROS) are free radicals and implicated in the development of a number of disease processes including artherosclerosis, neurodegenerative disorders, aging and cancer. ROS are byproducts of a number of in vivo metabolic processes and are formed deliberately as part of nor-mal inflammatory response. On the other hand, ROS are generated either as by products of oxygen reduction during xenobiotic metabolism or are liberated as the result of the futile redox cycling of the chemical agents including several chemical carcinogens. A better understanding of the mechanisms of free radical toxicity may yield valuable clue to risks associated with chemical exposures that leading to the development of chronic diseases including cancer. The molecular biology of ROS-mediated alterations in gene expression, signal transduction and carcinognesis is one of the important subjects in free radical toxicology. Epidemiological studies suggest that high intake of vegetables and fruits are associated with the low incidence of human cancer. Many phytopolyphenols such as tea polyphenols, curcumin, resveratrol, apigenin, genistein and other flavonoids have been shown to be cancer chemopreventive agents. Most of these compounds are strong antioxidant and ROS scavengers in vitro and effective inducers of antioxidant enzymes such as superoxide dismutatse, catalase and glutathione peroxidase in vivo. Several cellular transducers namely receptor tyrosine kinase, protein kinase C, MAPK, PI3K, c-jun, c-fos, c-myc, NFkB, IkB kinase, iNOS, COX-2, Bcl-2, Bax, etc have been shown to be actively modulated by phyto-polyphenols. Recent development in free radical toxicology have provided strong basis for understanding the action mechanisms of cancer chemoprevention.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2000년도 춘계학술대회
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• pp.6-7
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• 2000

Recently, free radicals such as active oxygen species, nitric oxide, etc are believed to be one of the key substances in physiological and pathological, toxicological phenomena, and oxidative damages, and all organism have defencing system against such as free radicals. Formation and extinction of free radicals may be regulated through bio-redox system, in which various enzymes and compounds should be involved in very complicated manner. Thus, direct and non-invasive measurement of in vivo free radical reactions with living animals must be essential to understand the role of free radicals in pathophysiological phenomena. Electron spin resonance spectroscopy (ESR) is very selective and sensitive technique to detect free radicals, but a conventional ESR spectrometer has large detect in application to living animals, since high frequent microwave is absorbed with water, resulting in generation of high fever in living body. In order to estimate in vivo free radical reactions in living whole animals, we develop in vivo ESR-CT technique using nitroxide radicals as spin probes. Nitroxide radicals and their reduced forms, hydroxylamines, are known to interact with various redox systems. We found that! ! the signal decay due to reduction of nitroxyl radicals is influenced by aging, inspired oxygen concentration, ischemia-referfusion injury, radiation, etc. In the present paper, I will introduce in vivo ESR technique and my laboratory recent results concerning non-invasive evaluation of free radical reactions in living mice.

• Food Science and Biotechnology
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• 제14권5호
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• pp.614-620
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• 2005

The antioxidative effect of Ecklonia cava, a brown marine alga, was investigated on radical scavenging, including 1,1-diphenyl-2-picrylhydrazyl (DPPH), and hydroxyl and alkyl radicals, using an electron spin resonance (ESR) technique, and on the inhibition of $H_2O_2$-induced DNA damage using comet assay. E. cava was enzymatically hydrolyzed with five food industrial proteases (Alcalase, Flavourzyme, Kojizyme, Neutrase and Protamex) to prepare water-soluble extracts. All the proteolytic hydrolysates exhibited strong dose-dependent radical scavenging activities (above 80%) at a concentration of $2.5\;{\mu}g/mL$. Kojizyme extract (obtained by proteolytic hydrolysation of E. cava with Kojizyme) showed the highest hydroxyl radical scavenging activity of around 98%. In addition, the $H_2O_2$-induced DNA damage was determined using a comet assay, which was quantified by measuring the tail length. Reduction of DNA damage increased with increasing concentrations of Kojizyme extract from E. cava. These results indicated that E. cava has a potential as a valuable natural antioxidative source.

• Food Science and Biotechnology
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• 제18권6호
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• pp.1505-1510
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• 2009

Arginyl-fructose (AF) and arginyl-fructosyl-glucose (AFG) were chemically synthesized and purified. Their in vitro and cellular antioxidant activity was investigated using oxygen radical absorbance capacity (ORAC) and cellular antioxidant activity assay, respectively. The peroxyl radical scavenging activity of AF was much higher than that of AFG, which was in good agreement with their reduction capacity to donate electrons or hydrogen atoms. On the other hand, the hydroxyl radical scavenging activity of AF was weaker than that of AFG, which was consistent with their metal chelating activity, suggesting that AFG-$Cu^{2+}$ complex may be less redox-active than AF-$Cu^{2+}$ complex due to 1 glucose molecule attached. The cellular antioxidant activity of AF and AFG appeared to depend on both their permeability into cell membrane and the scavenging activity on peroxyl or hydroxyl radicals. These results indicate that AF and AFG, Maillard reaction products, may have a high potential as a material for the development of nutraceutical food with antioxidant activity.

• 한국식품영양과학회지
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• 제29권2호
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• pp.268-273
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• 2000

To investigate an effect of the ethanol extract of Lycium chinense(EELC) on the activities of enzymes scavenging oxygen free radicals or detoxicating alcohol. The ground Lycium chinense was extracted with 30% edible ethanol and then diluted with 6% ethanol to contain 2% EELC(w/v). Three different groups of male Sprague-Dawley rats had taken a drink EELC, ethanol(ETH) or water(control), respectively for 2 months. At the end of experimental period, the animals were sacrificed and obtained the following findings. The EELC-treated animals showed the highest activity of hepatic glucose-6-phosphatase among three groups. The activities of xanthine oxidase and cytochrome p-450 from EELC treatment group were lower than those from ETH-treated group. However, the activity of superoxide dismutase was higher in the EELC-treated group than the ETH-treated(p<0.005). Furthermore, hepatic alcohol or aldehyde dehydrogenase activity, and glutathione content and glutathione peroxidase were significantly higher in EELC-treated animals than in ETH-treated those. The activity of glutathione S-transferase in liver was appeared the orderly higher value in EELC, ETH and control-treated group. As the result, EELC may affect the reduction of oxygen free radical production and help the detoxication of ethanol.

• 대한약리학회지
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• 제21권1호
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• pp.12-26
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• 1985

흰쥐 뇌 미토콘드리아에 의한 $O^{-}_{2}{\cdot}$ 의 생성과 이 radical의 유해작용 및 그 작용기전을 알아보기 위하여 본실험을 수행하였다. Succinate와 antimycin존재하에서 미토콘드리아는 $O^{-}_{2}{\cdot}$을 생성하였으며 이는 SOD-inhibitable NBT환원으로 확인되었다. 동일 조건에서 $H_2O_2$는 일차생성물인 $O^{-}_{2}{\cdot}$의 dismutation으로 생성됨을 알수 있었다. 상기조건에서 미토콘드리아의 막지질이 파괴되었고 반응액에 첨가된 isocitrate dehydrogenase와 적혈구에 각각 불활성화와 용혈이 초래되었다. 이같은 작용은 $Fe^{++}$이 있을때만 관찰 되었다. 그리고 독작용은 superoxide dismutase 혹은 castalase에 의해서 억제되었다. 또한 methional을 첨가하였을 때 ethylene이 생성되었으며 그 생성은 $Fe^{++}$에 의하여 현저히 증가하였다. Ethylene 생성 역시 상기 효소에 의하여 억제되었다. 따라서 미토콘드리아에서 발생된 $O^{-}_{2}{\cdot}$은 거대분자 및 세포에 독성을 나타낼수 있으며 이같은 작용은 $Fe^{++}$의 촉매작용에 의한 $O^{-}_{2}{\cdot}$와 $H_2O_2$의 상호작용으로 발생되는 $OH{\cdot}$ 에 의한것으로 추측되었다. 이상의 결과는 미토콘드리아가 유독성 산소 radical을 발생하므로 조직손상을 시킬 수 있다는 가능성을 시사하는 증거라고 생각되었다.