• 한국자기공명학회논문지
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• 제11권1호
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• pp.56-63
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• 2007

A series of bromophenols and corresponding debrominated phenolic compounds was prepared by isolation from red alga Tichocarpus crinitus and by structural modification of natural bromophenols. Their structures were determined by extensive NMR analysis and the antioxidant activities were established through the determination of their abilities to inhibit free radicals using DPPH as the stable radical. The most active free radical scavengers were the debrominated phenolic derivatives 3,4-dihydroxybenzyl alcohol and 3,3',4,4'-tetrahydroxydiphenylmethane.

• Journal of Microbiology and Biotechnology
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• 제10권2호
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• pp.233-237
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• 2000

As part of a continuing investigation to identify free radical scavengers from the fruit bodies of basidiomycetes, we isolated two p-terphenyl compounds, designated as PAl and PA2l, from cethanolic extract of the fruit body of Pasillus panuoides. The methanolic extract was processed by ethyl acetate extraction and silica gel column chromatography to yield two active fraction. PAl was obtained from one of the fractions through Sephadex LH-20 and silica gel column chromatographies and reverse-phase HPLC. The other fraction was purified by Sephadex LH-20 and reverse-phase column chromatographies to produce PA2. The compounds PA1 and PA2 were identified as leucomentin-4 and leucomentin-2, respectively, on the basis of various spectroscopic analyses. These compounds exhibited strong inhibitory activities against lipid peroxidation in rat liver microsomes with IC_{50}$ values of 0.10 and $0.06{\;}\mu\textrm{g}ml$, respectively.

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 2001년도 추계학술대회 및 정기총회
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• pp.92-92
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• 2001

ICAP법을 이용하였을 때 뇌내 약물량은 SS20-0098은 PBN보다 4.5배 큰 값을 나타내었고 정맥투여 후 2시간에서의 뇌내 약물량은 SS20-0098과 PBN이 거의 유사한 값을 나타내었다. PBN과 SS20-0098은 octanol partition 계수(log P)가 각각 1.23, 2.26로 지용성인 큰 SS20-0098이 혈액 내에서 대사를 저지시키는 방법으로 투여되었을 때는 비교적 더 많은 양이 뇌로 이행되고 있음을 알 수 있었다.

• Environmental Analysis Health and Toxicology
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• 제8권3_4호
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• pp.33-41
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• 1993

This study was designed to determine the hemolytic mechanism of antitumor agent tetraphosphine platinum (II) complex (RC-1), which was synthesized recently. Erythrocytes treated with RC-1 showed concentration and time dependent lipid peroxydation, methemoglobin synthesis and hemolysis. And also treatment of radical scavengers showed the inhibitory effect of hemolysis and the decrease of malondialdehyde levels in RC-1 treated erythrocytes. So, the mechanism of hemolysis was considered to be the generation of free radicals, methemoglobin synthesis and the lipid peroxidation of phospholipid which composed of erythrocyte membrane.

• Natural Product Sciences
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• 제14권3호
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• pp.202-205
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• 2008

The antioxidant activity of Paeonia suffruticosa (Paeoniaceae) was determined by measuring the radical scavenging effect on DPPH (1,1-diphenyl-2-picrylhydrazyl). The methanolic extract of P. suffruticosa showed the strong antioxidant activity. The antioxidant activity of ethyl acetate soluble fraction was stronger than that of the others ($IC_{50}$, $1.2\;{\mu}g/mL$), and the fraction was subjected to purification by repeated silica gel and Sephadex LH-20 column chromatography. Suffruticosol A, suffruticosol B, methyl gallate, and gallic acid, were isolated from the ethyl acetate soluble fraction. Their structures were elucidated by physico-chemical and spectroscopic studies.

• Natural Product Sciences
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• 제17권2호
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• pp.142-146
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• 2011

In the course of screening for antioxidant compounds by measuring the radical scavenging effect on 1,1-diphenyl- 2-picrylhydrazyl (DPPH), a total extract from the whole plant of Veronica peregrina (Scrophulariaceae) was found to show potent antioxidant activity. Subsequent activity-guided fractionation of the methanolic extract led to the isolation of six phenolic compounds including chrysoeriol (1), diosmetin (2), 4-hydroxybenzoic acid (3), apigenin (4), caffeic acid methylester (5) and protocatechuic acid (6). Their structures were elucidated by spectroscopic studies. Compounds 1-5 were isolated for the first time from this plant. Compounds 5 and 6 showed significant antioxidative effects in DPPH free radical scavenging and superoxide quenching activity assays.

• Archives of Pharmacal Research
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• 제18권3호
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• pp.159-163
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• 1995

Previously, we have reported that methylene blue (MB) induces cytotoxicity in human brain tumor cells through the generation of free radicals. In this study the effect of deferoxamine (DFO), an iron chelator, on MB-induced cytotoxicity was investigated using SK-N-MC human neuroblastoma and U-373 MG human astrocytoma cells as model cellular systems. The cytotoxic effect of MB was potentiated by DFO. The potentiation effect of DFO was significantly blocked by either stoichiometric amounts of ferric ion, various antioxidants, hydroxyl radical scavengers or intracellular $Ca^{2+}$ release blockers. These results suggest that hydroxyl radical and intracellular $Ca^{2+}$ may act as important mediators of the enhanced cytotoxicity by MB and DFO. These results further suggest that the combined treatment with MB and DFO may be useful for the therapeutical applications of human brain tumors.

• 한국약용작물학회지
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• 제11권1호
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• pp.1-4
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• 2003

천연물로부터 항산화 활성물질을 목적으로 DPPH 자유 라디칼 소거활성 검색법을 이용하여 검색을 실사하고, 유의한 활성을 나타낸 산국 메탄올 추출물로부터 2종의 화합물을 분리하고 기기분석을 이용하여 화합물 1과 2의 구조를 apigenin과 acacetin-7-O-rutinoside (Linarin)으로 동정하였다. 이들 화합물은 각각 13.3 및 $42.1{\mu}g$의 농도에서 DPPH 라디칼을 50% 소거하는 활성을 나타내었으며, 화합물 1은 양성 대조양물인 L-ascorbic acid $(RC_{50}\;=\;13.1{\mu}g)$에 비하여 강한 활성을 나타내었다.

• Archives of Pharmacal Research
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• 제25권4호
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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.

• Molecules and Cells
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• 제22권2호
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• pp.220-227
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• 2006

Oxidative alteration of mitochondrial cytochrome c has been linked to disease and is one of the causes of proapoptotic events. We have investigated the modification of cytochrome c by $H_2O_2$. When cytochrome c was incubated with $H_2O_2$, oligomerization of the protein increased and the formation of carbonyl derivatives and dityrosine was stimulated. Radical scavengers prevented these effects suggesting that free radicals are implicated in the $H_2O_2$-mediated oligomerization. Oligomerization was significantly inhibited by the iron chelator, deferoxamine. During incubation of deoxyribose with cytochrome c and $H_2O_2$, damage to the deoxyribose occurred in parallel with the release of iron from cytochrome c. When cytochrome c that had been exposed to $H_2O_2$ was analyzed by amino acid analysis, the tyrosine, histidine and methionine residues proved to be particularly sensitive. These results suggest that $H_2O_2$-mediated cytochrome c oligomerization is due to oxidative damage resulting from free radicals generated by a combination of the peroxidase activity of cytochrome c and the Fenton reaction of free iron released from the oxidatively-damaged protein.