• Korean Journal of Pharmacognosy
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• v.42 no.2
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• pp.110-116
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• 2011

As part of our ongoing study focused on the discovery of antioxidants from natural products by measuring the DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging activity, methanol extract of flowers of Carthamus tinctorius L. was found to show potent antioxidant activity. Activity-guided fractionation of the methanol extract lead to the isolation of twenty compounds including two flavonol glycosides, quercertin-3-O-${\beta}$-D-glucopyranoside (12) and kaempferol-3-O-${\alpha}$-L-rhamnopyranosyl-${\beta}$-D-glucopyranoside (18), two flavanone glycosides, (2S)-4',5,6,7-tetrahydroxyflavanone 6-O-${\beta}$-D-glucopyranoside (15) and (2R)-5,7,8',4-tetrahydroxyflavanone 8-O-${\beta}$-D-glucopyranoside (16), and two acetylenic glycosides, 8Z-decaene-4,6-diyne-1-O-${\beta}$-D-glucopyranoside (13) and 4,6-decadiyne-1-O-${\beta}$-D-glucopyranoside (14). Their chemical structures were identified by using spectroscopic analysis. Among them, compounds 12-18 were tested in DPPH assay. Compounds 13-16 were first reported to their antioxidant activity. Quercertin-3-O-${\beta}$-D-glucopyranoside (12) showed the most potent inhibitory effect on DPPH with $IC_{50}$ value of 56.7 ${\mu}M$.

• Preventive Nutrition and Food Science
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• v.7 no.1
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• pp.18-21
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• 2002

The extract of Ginkgo biloba leaves was measured for inhibitory activity against xanthine oxidase. Aceton extract of G. biloba leaves showed strong inhibitory activity. Inhibitory activities of the fractionated extract were in the order of water > ethyl acetate fractions. Two fractions exhibiting strong inhibitory activities ware further purified via repeated silica gel, Amberlite IRN-78, Polyclar AT, and Sephadex LH-20 column chromatographies. Active components were isolated and identified through $^1$H-NMR and $^{13}$ C-NMR. The compounds were characterized as kaempferol 3-Ο-$\alpha$-(6$^{"′}$-p-coumaroylglucosyl-$\beta$-1,4-rhamnoside), and quercertin 3-Ο-$\alpha$-(6$^{′}$-p-coumaroylglucosyl-$\beta$-1,4-rhamnoside).

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.4
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• pp.687-692
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• 1998

To use onion(Allium cepa L.) residue as raw materials of food product, yields of onion-juice according to various extracting methods and optimal extracting condition of quercetin and its related glycosides were carried out. Onion juices gained by the methods of pressing, rotary crushing, freeze pressing and enzyme treatment. The yield by the method of enzyme treatment was higher than others. The yields of juice from fresh onion and heat-treated onion(8$0^{\circ}C$/10min) by pressing were 66% and 83%, respectively. Ethanol extraction of onion was efficient at 75$^{\circ}C$ and acetic acid extraction was proper at 3% concentration for 3 hours at 11$0^{\circ}C$. The onion extract was fractionated in the order of hexane, chloroform, ethylacetate and butanol to test flavonoids. The highest abundant flavonoids were found in ethylacetate and butanol fraction.

• Korean Journal of Medicinal Crop Science
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• v.14 no.3
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• pp.148-152
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• 2006

Comparison of four phenolic compounds among three different parts of Panax ginseng C.A. Meyer was performed in this study. Contents of esculetin, p-coumaric acd, quercetin, maltol in the ethyl acetate fraction were determinated by HPLC analysis. The main root has a highest concentration of p-coumaric acid and the leave has a highest concentration of quercetin and esculetin. This ethyl acetate fraction of the leaves exhibited higher depigmenting activity and lower cell toxicity than the other parts of ginseng. In addition, it showed that quercetin and esculetin among phenolic compounds highly inhibited melanin biosynthesis in ginseng. It implies that leaves of ginseng may be used as skin whitening herb. Quercetin and esculetin proved to be active compounds in the leaves of ginseng.

• Herbal Formula Science
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• v.26 no.3
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• pp.183-193
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• 2018

Objectives : In Traditional Korean Medicine, Epimedium koreanum Nakai has diverse pharmacological activities to treat impotence, forgetfulness, cataract and exophthalmos. Present study investigated anti-fibrogenic effects of E. koreanum water extract (EKE) in hepatic stellate cells (HSCs). Methods : To study anti-fibrogenic effects of EKE, LX-2 cells, a human immortalized HSCs, were pre-treated with $3-300{\mu}g/mL$ of EKE, and then subsequently exposed to 5 ng/mL of transforming growth $factor-{\beta}1$ ($TGF-{\beta}1$). Expression level of ${\alpha}-smooth$ muscle actin was determined by immunoblot analysis. Phosphorylation of Smad, transactivation of Smad, and expression of plasminogen activator inhibitor-1 (PAI-1) were monitored to investigate the effect of EKE on $TGF-{\beta}1-mediated$ signaling pathway. Results : Up to $100{\mu}g/mL$, EKE did not show any cytotoxicity on LX-2 cells. Pre-treatment of EKE ($100{\mu}g/mL$) significantly inhibited ${\alpha}-smooth$ muscle actin expression induced by $TGF-{\beta}1$. In addition, EKE significantly decreased Smad2 and Smad3 phosphorylations, Smad binding element-driven luciferase activity and PAI-1 expression by $TGF-{\beta}1$. Of three flavonoid compounds found in EKE, only quercertin ($30{\mu}M$) attenuated $TGF-{\beta}1-mediated$ PAI-1 expression. Conclusion : These results suggest that EKE has an ability to suppress fibrogenic process in HSCs via inhibition of $TGF-{\beta}1/Smad$ signaling pathway.

• Korean Journal of Food Science and Technology
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• v.35 no.2
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• pp.266-271
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• 2003

Insoluble polyphenol antioxidants, quercetin and catechin, were stabilized through the complexation with cyclodextrin to increase heat and pH stabilities. Comparison of inclusion complex formabilities of quercetin and catechin with ${\alpha}-,\;{\beta}-$, and ${\gamma}-CDs$ revealed ${\beta}-CD$ to be the most suitable result. Optimal molar mixing ratio of ${\beta}-CD$ and quercetin or catechin for inclusion complex formation was found to be 1 : 1. Inclusion complexation was confirmed using differential scanning calorimetry. Solubility of ${\beta}-CD-antioxidant$ inclusion complexes increased compared with native antioxidants, Stability against temperature and pH of ${\beta}-CD-antioxidant$ inclusion complex analyzed revealed antioxidant activities of ${\beta}-CD-quercetin$ and catechin inclusion complexes have higher stabilization compare to raw quercetin and catechin. Peroxide value of linoleic acid dissolved in water decreased substantionally after using ${\beta}-CD-quercetin$ inclusion complex. ${\beta}-CD-antioxidant$ inclusion complex can be used effectively as a fresh-food preservative.