• Journal of the Korean Wood Science and Technology
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• v.30 no.4
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• pp.51-57
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• 2002

Antimicrobial and antioxidative activites on heartwood extractives of domestic species were investigated to develop a natural fungicide or preservative. One steroid, stilbene derivatives and two flavonoids were isolated from heartwood of Robinia pseudo-acacia which has been selected due to its high antioxidative activity among the tested species. The structures were determinded as: 3-𝛽-stigmast-5-en-3-ol(daucosterol), 3,3'4,5-tetrahydroxystilbene, 3,3'4'5,7-pentahydroxyflavone(robinetin) and 3,3'4'7-tetrahydroxyflavanone(fustin) respectively on the basis of spectroscopic data and chemical correlations. According to the results of free radical scavenging activity, 3,3'4'5,7-pentahydroxyflavone was evaluated as the highest antioxidative compound among the four compounds and showed higher radical scavenging activity than those of 𝛼-tocopherol and butylated hydroxytoluene(BHT), one of the strongest synthetic antioxidants. 3,3'4'5-Tetrahydroxystilbene and 3,3'4'7-tetrahydroxyflavanone showed higher antioxidative activities than that of 𝛼-tocopherol. However, 3-𝛽-stigmast-5-en-3-ol did not show free radical scavenging activity. In this regard, it could inferred that high antioxidative activity of extractives of R. pseudo-acacia was derived from 3,3'4'5'7-pentahydroxyflavone, 3,3'4'5-tetrahydroxystilbene and 3,3'4'7-tetrahydroxyflavanone.

• Journal of the Korean Wood Science and Technology
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• v.28 no.2
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• pp.42-48
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• 2000

Two stilbenoids and two flavonoids were isolated from ethylacetate fraction of ethanol extract of Morns bombycis heartwood. These four compounds were identified 2',3,4',5-tetrahydroxystilbene(oxyresveratrol), 3,4',5-trihydroxystilbene (resveratrol) as stilbenoids, and 2',3,4',5,7-pentahydroxyflavone(morin), 3,4',5,7-tetrahydroxyflavan((+)-afzelechin) as flavonoids by Mass and NMR spectroscopic analysis.

• Biomolecules & Therapeutics
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• v.6 no.4
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• pp.378-382
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• 1998

In the previous screening on antidiabetic effect of Lycii fructus by glucose transport method using $N_2$-STZ diabeted rat model, each extracts showed the potent antidiabetic activity. We obtained three compounds isolated from the water fraction, EtOAc fraction and n-BuOH fraction of Lycii fructus in the present work and their structures were identified as 1-carboxy-N,N,N-trimethylmethanaminium hydroxide inner salt, 2,4(1H,3H)-pyrimidinedione and 3,3',4',5,7-pentahydroxyflavone-3-rutinoside . Among the constituents separated from Lycii fructus, 2,4(IH,3H)-pyrimidinedione, 3,3',4',5,7-pentahydroxyflavone-3-rutinoside and ascorbic acid were shown a remarkable antidiabetic effect.

• Journal of the Korean Wood Science and Technology
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• v.28 no.3
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• pp.78-84
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• 2000

Two flavanones and one flavone were isolated from the diethylether soluble fraction of ethanol extract of Larix leptolepis heartwood. These compounds were identified 3,3',4',5,7-pentahydroxyflavanone(taxifolin), 3,4',5,7-tetrahydroxyflavanone(aromadendrin) and 3,3',4',5,7-pentahydroxyflavone(quercetin) by instrumental analyses using UV, IR, MS and NMR spectrometries. Antioxidative activies of these compounds were investigated by 1,1-diphenyl-2-picrylhydrazyl(DPPH) free radical scavenging activity. Quercetin and taxifolin indicated high free radical scavenging activities compared to ${\alpha}$-tocopherol and BHT(butylated hydroxytoluene).

• Journal of Applied Biological Chemistry
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• v.49 no.3
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• pp.114-116
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• 2006

• Preventive Nutrition and Food Science
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• v.11 no.2
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• pp.171-175
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• 2006

Alnus japonica Steud (Betulaceae) has long been used as a Korean traditional medicine for gastric disorders, hepatitis, and fatty liver. As a part of our study on the identification of secondary metabolites of naturally occurring bioactive compounds, we isolated 1,7-bis(4-hydroxyphenyl)-3,5-heptanediol(1), 5-hydroxy-1,7bis(4-hydroxyphenyl)-3-heptanone(2), 5,3'-dihydroxy-7,4'-dimethoxyflavone(3) and 3,5,7,3',4'-pentahydroxyflavone(4) from the dichloromethane and ethylacetate-soluble fractions of Alnus japonica Steud. These compounds showed significant antioxidant activity in a concentration-dependent manner. The $IC_{50}$ values of compounds 1, 2, 3 and 4 were 30.1, 37.4, 20.2 and 13.7 ${\mu}g/mL$, respectively, through the scavenging capacity of 1,1-diphenyl-2-picrylhydrazyl radical assay.

• Korean Journal of Food Science and Technology
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• v.29 no.3
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• pp.595-600
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• 1997

The antioxidant activity of the solvent fractions extracted from onion skin was examined. The antioxidant activity of methanol extract at the cencentration of 0.02% and 0.03% was stronger than that of mixed tocopherol. The antioxidant activity of the fractions of methanol extract increased in the order of butanol> ethyl acetate> ethyl ether> water fraction. The antioxidant activity of each fractions was strongly related with total phenol content and HDA. Further separation of butanol fraction by TLC yielded 6 fluorescent bands with Rf values of 0.20, 0.33, 0.49, 0.60 and 0.94. The total phenol content and HDA of fluorescent band, Rf 0.96, were remarkable higher than those of the other band and exhibited a strong UV absorption at 255 nm and 317 nm, which would be specifically produced by flavonol. Spectral analyses indicated that the major antioxidant component was quercetin aglycone (3,3',4',5,7-pentahydroxyflavone).

• The Korean Journal of Physiology and Pharmacology
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• v.15 no.5
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• pp.279-283
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• 2011

Quercetin (3,3',4',5,7-pentahydroxyflavone) is an attractive therapeutic flavonoid for cancer treatment because of its beneficial properties including apoptotic, antioxidant, and antiproliferative effects on cancer cells. However, the exact mechanism of action of quercetin on ion channel modulation is poorly understood in bladder cancer 253J cells. In this study, we demonstrated that large conductance $Ca^{2+}$-activated $K^+$ ($BK_{Ca}$) or MaxiK channels were functionally expressed in 253J cells, and quercetin increased $BK_{Ca}$ current in a concentration dependent and reversible manner using a whole cell patch configuration. The half maximal activation concentration ($IC_{50}$) of quercetin was $45.5{\pm}7.2{\mu}m$. The quercetin-evoked $BK_{Ca}$ current was inhibited by tetraethylammonium (TEA; 5 mM) a non-specific $BK_{Ca}$ blocker and iberiotoxin (IBX; 100 nM) a $BK_{Ca}$-specific blocker. Quercetin-induced membrane hyperpolarization was measured by fluorescence-activated cell sorting (FACS) with voltage sensitive dye, bis (1,3-dibutylbarbituric acid) trimethine oxonol ($DiBAC_4$2(3); 100 nM). Quercetin-evoked hyperpolarization was prevented by TEA. Quercetin produced an antiproliferative effect ($30.3{\pm}13.5%$) which was recovered to $53.3{\pm}10.5%$ and $72.9{\pm}3.7%$ by TEA and IBX, respectively. Taken together our results indicate that activation of $BK_{Ca}$ channels may be considered an important target related to the action of quercetin on human bladder cancer cells.

• Food Science and Biotechnology
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• v.16 no.5
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• pp.747-752
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• 2007

This study was carried out to identify and quantify the flavonoids from 6 different plant parts of Allium victorialis var. platyphyllum (AVP), including the flower, leaf, root, stem, flower stalk, and flower seed, using liquid chromatography/ mass spectrometry. Two major flavonoids were structurally identified as quercetin (3,5,7,3'4,'-pentahydroxyflavone) and kaempferol (3,5,7,4'-tetrahydroxyflavone) at contents of 11.8-25.8 and $6.0-64.4\;{\mu}g/mL$, respectively. In particular, the flower and root plant parts contained the highest amounts of quercetin and kaempferol compared to the other parts. We also assessed the recovery effects of each plant-part extract of AVP on gap junctional intercellular communication (GJIC) in WB-F344 cells by the scrape-loading and dye transfer (SL/DT) method. According to the results, GJIC was reduced by approximately 70.2% ($62.3{\pm}12.5$ cells) compared to the control ($209{\pm}9.5$ cells, 100%) when 12-O-tetradecanoylphorbol-13-acetate (TPA) was treated alone in the WB-F344 rat liver epithelial cells. However, the stem extract (0.2 mg/mL) restored GJIC to basal levels (92%, $204{\pm}2.3$ cells, p<0.01) and the flower extract (0.2 mg/mL) stimulated GJIC to 82.5% ($172.6{\pm}8.3$ cells, p<0.05), when applied together with the TPA.

• Journal of Physiology & Pathology in Korean Medicine
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• v.25 no.5
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• pp.830-836
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• 2011

The leaf of mulberry (Morus alba L) has long been used in Oriental medicine for the prevention or treatment of several diseases. However, little is known about the inhibitory effects of a single compound isolated from the mulberry leaves on inflammatory response. We are isolate a single compound of quercetin (3,3',4',5,7-pentahydroxyflavone) and astragalin (kaempferol-3-O-glucopyranoside) from the mulberry leaves, and then investigate the anti-inflammatory effects of quercetin, astragalin or quercetin plus astragalin in lipopolysaccharide (LPS)-stimulated murine peritoneal macrophages. Each compound suppressed the production of inflammatory mediators (NO, $PGE_2$ and IL-6) in LPS-stimulated murine peritoneal macrophages in a dose-dependent manner. Especially, the cotreatment of quercetin (2.5 ${\mu}M$) and astragalin (2.5 ${\mu}M$) markedly suppressed the production and the expression of inflammatory mediators. These suppressive effects were synergistically increased by their combination. These results suggest that the combination of quercetin and astragalin from the mulberry leaves may be useful for therapeutic drugs against inflammatory immune diseases, probably by suppressing the production of inflammatory mediators.