• 대한한방내과학회지
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• 제17권1호
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• pp.265-277
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• 1996

Jwagyuyeum and Woogyuyeum, being known to reinforce Kidney-yin and -yang, were tested for the effects of on free radical generating enzyme and lipid peroxidation in rat's kidney. In vitro, levels of lipid peroxide in tissues of brain were proportionally decreased to concentration of extracts prepared from Jwagyuyeum and Woogyuyeum. They were much more decreased, when lipid peroxidation was induced with ferrous iron (Fe+2), In vivo, after both herbs were administered to the rat, levels of lipid peroxide in kidney were decreased only in Jwagyuyeum. The enzyme activities and the ratio of type conversion of xanthine oxidase were decreased only in Jwagyuyeum. But, We can't see special changes in Woogyuyeum. The enzyme activities of aldehyde oxidase was lowered in both herbs, especially Jwagyuyeum was much more done. These results suggest that Jwagyuyeum and Woogyuyeum decrease the activities of free radical generating enzymes such as xanthine oxidase and aldehyde oxidase which form lipid peroxide.

• Macromolecular Research
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• 제15권4호
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• pp.385-391
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• 2007

Block copolymer micelles are generally formed via the self-assembly of amphiphilic block copolymers in an aqueous medium. The hydrophilic and hydrophobic blocks form shell and core micelles, respectively. The block copolymers of methoxy poly(ethylene glycol) (MPEG)-b-poly(2-diisopropylamino)ethyl methacrylate (PDPA) were synthesized via atom transfer radical polymerization, with the macro initiator synthesized by the coupling of 2-bromoisobutyryl bromide with MPEG in the presence of a triethyl amine base catalyst. The atom transfer radical polymerization of 2-diisopropylamino)ethyl methacrylate was performed in conjunction with an N,N,N',N",N"-pentamethyl-diethylenetriamine/copper bromide catalyst system, in DMF, at $70^{\circ}C$. The pH induced micellization/demicellization was studied using fluorescence, with a pyrene probe. Furthermore, the pH dependent micellization was confirmed using the microviscosity method, with a dipyme fluorescence probe. The pH dependant micelle size distribution was studied using dynamic light scattering. The characterization of the synthesized polymers was established using gel permeation chromatography and from the $^1H-nuclear$ magnetic resonance spectroscopy.

• 한국수소및신에너지학회논문집
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• 제18권2호
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• pp.157-163
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• 2007

During PEMFC operation, low current and low humidity conditions accelerate the degradation of perfluorosulfonic acid membrane. But, there have been no studies that clearly explain why these conditions accelerate the membrane degradation. In this study, the hydrogen permeability through the membrane, I-V polarization of MEA, fluoride emission rate(FER) in effluent water were measured during cell operation under low current densities and low relative humidity(RH). The experimental results were evaluated with oxygen radical mechanism the most commonly known for membrane degradation. It seems that low RH of anode is a good condition for $H{\cdot}$ radical formation on the Pt catalyst and the low current condition accelerates the $H{\cdot}$ to form $HO_2{\cdot}$ radical attacking the polymer membrane.

• Food Science and Biotechnology
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• 제15권3호
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• pp.357-362
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• 2006

We assessed various antioxidant activities, such as 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, 2,2'-azino-bis 3-ethylbenz-thiazoline-6-sulfonic acid (ABTS) radical, and reactive oxygen species (ROS) radical scavenging effect, along with antioxidant capacity, of soybean oil with added Citrus species peel extracts (CPEs). These extract oils showed higher radical scavenging effects than grape fruit seed extract, the natural antioxidant agent, did. When CPEs were added to soybean oil, they showed peroxide value (POV) and acid value (AV) increasing inhibition effects. Furthermore, none of the CPEs showed any cytotoxicity over the tested concentration range of 0.01-100 ppm. The major flavonoid contents of Citrus junos, as determined by HPLC, were naringin ($7.5\;{\mu}g/mg$) and neohesperidin ($7.5\;{\mu}g/mg$), and those of Citrus unshiu were narirutin ($3.13\;{\mu}g/mg$) and hesperidin ($1.97\;{\mu}g/mg$). However, the aglycone form was not found. This study showed that CPEs might be a potent source of natural antioxidant, without any toxic effects.

• Applied Biological Chemistry
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• 제47권2호
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• pp.283-286
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• 2004

In the course of screening for reactive oxygen species scavengers from natural products, two antioxidants were isolated from the edible mushroom Polyozellus multiflex and identified as polyozellin and thelephoric acid. Thelephoric acid inhibited 45.7% of the super oxide anion radical, 74.6% of the hydroxyl radical, and 44.0% of the DPPH radical at 0.1 mM, while the positive control ${\alpha}-tocopherol$ did 22.1%, 75.6%, and 26.5% of each radical, respectively. Polyozellin, the reductive acetylated form of thelephoric acid, showed almost same scavenging activity against above mentioned radicals. The isolated compounds showed scavenging activity on the superoxide anion radical in the ESR method ($IC_{50}$ of polyozellin and thelephoric acid were $218.0\;{\mu}M$ and $21.1\;{\mu}M$, respenctively). However, they showed no significant activity on the hydrogen peroxide radical.

• 충청수학회지
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• 제16권1호
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• pp.103-112
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• 2003

We consider multiplier ideals on CR manifolds, which is associated to Kiremidjian's work on CR embedding problem. Similar to the Kohn's result, we found that the multipliers form a nontrivial radical ideal.

• Journal of Ginseng Research
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• 제31권4호
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• pp.230-236
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• 2007

본 연구는 증숙 횟수에 따른 인삼의 총페놀 화합물 함량과 페놀산 획분의 DPPH, ABTS 라디칼 소거활성을 시험하고, 개별 페놀산 조성과 함량을 GC로 분석하였다. 총페놀 함량은 0.53-2.89%로 증숙 횟수에 비례하여 증가하였다. 결합 형태에 따른 페놀산 획분의 함량은 결합형 >에스테르형>유리형 순으로 나타났으며, 이들 세 획분의 총량 (1.03-1.41%)은 증숙횟수에 영향을 받지 않았다. 각 획분에서 salicylic, cinnamic, p-hydroxybenzoic, gentisic, vanillic, syingic, caffeic, ferolic acid가 확인되었으며, 이 중 gentisic acid와 ferulic acid 가 주된 페놀산으로 50% 이상을 차지하였다. 각 페놀산 획분은 50% 이상의 DPPH와 ABTS 라디칼 소거활성을 보였으며, 결합형태에 따른 페놀산 획분 간에는 큰 차이가 없었다. 반면 각 획분별로 증숙 횟수에 따라 라디칼 소거활성이 차이를 보였으며, 증숙 횟수가 증가할수록 라디칼 소거활성도 증가하는 경향을 보였다.

• 한국응용과학기술학회지
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• 제25권2호
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• pp.168-174
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• 2008

This study is focused on the antimicrobial activity of cyanobacteria Microcystis aeruginosa by the reduction and oxidation reaction of copper and zinc alloy metal fiber filter. Cu/Zn ion is easily makes radicals with molecular hydroperoxide. Especially, hydroperoxide radical shows strong toxicity to the strains. Plasma membrane causes conformational change when hydroperoxide radical binds to plasma membrane. Elution of copper ion from copper and zinc alloy metal fiber is detected in the cyanobacteria solution as 0.5 ppm, and that of zinc ion is 0 ppm respectively. Zinc ion is figured to form a hydroxide in the cyanobacteria solution and precipitated to form a sludge. The concentration of chlorophyll-a in the cyanobacteria solution was proved to be the index of antimicrobial level of Microcystis aeruginosa.

• Preventive Nutrition and Food Science
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• 제19권1호
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• pp.40-48
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• 2014

Laver is one of the most consumed edible red algae seaweeds in the genus Porphyra. Laver is primarily prepared in the form of dried, roasted, and seasoned products. We investigated the total polyphenol and flavonoid contents of laver products, and evaluated the in vitro antioxidant properties of solvent extracts from commercially processed laver products. Significant differences in the concentration of phenolic compounds were found among differently processed laver. The total phenolic content for laver extracts ranged from 10.81 mg gallic acid equivalent (GAE)/g extract to 32.14 mg GAE/g extract, depending on extraction solvent and temperature. Laver extracts contained very few flavonoids (0.55 mg catechin equivalent/g extracts to 1.75 mg catechin equivalent/g extracts). 2,2-Diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS), hydroxyl radical, and superoxide anion scavenging assays were used to determine the radical scavenging capacities of laver extracts. These assays revealed that the processing method and extraction condition affected the antioxidant potentials of laver. Antioxidant activity of dried laver, roasted laver, and seasoned laver increased in a concentration-dependent manner ($100{\sim}1,000{\mu}g/mL$). The radical scavenging activities of $37^{\circ}C$ and $100^{\circ}C$ water extracts were lower than that of a $37^{\circ}C$ 70% ethanol extract. The highest radical scavenging capacity was observed in the $37^{\circ}C$ 70% ethanol extracts of dried laver, roasted laver, and seasoned laver. Overall, these results support that notion that laver contains bioactive compounds, such as polyphenols and flavonoids, which may have a positive effect on health.

• Environmental Engineering Research
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• 제12권5호
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• pp.211-217
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• 2007

Polycyclic aromatic hydrocarbon growth from cyclopentadiene (CPD) pyrolysis was investigated using a laminar flow reactor operating in a temperature range of 600 to $950^{\circ}c$. Major products from CPD pyrolysis are benzene, indene and naphthalene. Formation of observed products from CPD is explained as follows. Addition of the cyclopentadienyl radical to a CPD $\pi$-bond produces a resonance-stabilized radical, which further reacts by one of three unimolecular channels: intramolecular addition, C-H bond $\beta$-scission, or C-C bond $\beta$-scission. The intramolecular addition pathway produces a 7-norbornenyl radical, which then decomposes to indene. Decomposition by C-H bond $\beta$-scission produces a biaryl intermediate, which then undergoes a ring fusion sequence that has been proposed for dihydrofulvalene-to-naphthalene conversion. In this study, we propose C-C bond $\beta$-scission pathway as an alternative reaction channel to naphthalene from CPD. As preliminary computational analysis, Parametric Method 3 (PM3) molecular calculation suggests that intramolecular addition to form indene is favored at low temperatures and C-C bond $\beta$-scission leading to naphthalene is predominant at high temperatures.