• Natural Product Sciences
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• v.21 no.3
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• pp.162-169
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• 2015

Hamamelis japonica (Hamamelidaceae), widely known as Japanese witch hazel, is a deciduous flowering shrub that produces compact clumps of yellow or orange-red flowers with long and thin petals. As a part of our ongoing search for phenolic constituents from this plant, eleven phenolic constituents including six flavonol glycosides, a chalcone glycoside, two coumaroyl flavonol glycosides and two galloylated compounds were isolated from the flowers. Their structures were elucidated as methyl gallate (1), myricitrin (2), hyperoside (3), isoquercitrin (4), quercitrin (5), spiraeoside (6), kaempferol 4'-O-β-glucopyranoside (7), chalcononaringenin 2'-O-β-glucopyranoside (8), trans-tiliroside (9), cis-tiliroside (10), and pentagalloyl-O-β-D-glucose (11), respectively. These structures of the compounds were identified on the basis of spectroscopic studies including the on-line LCNMR-MS and conventional NMR techniques. Particularly, directly coupled LC-NMR-MS afforded sufficient structural information rapidly to identify three flavonol glycosides (2 - 4) with the same molecular weight in an extract of Hamamelis japonica flowers without laborious fractionation and purification step. Cytotoxic effects of all the isolated phenolic compounds were evaluated on HCT116 human colon cancer cells, and pentagalloyl-O-β-D-glucose (11) was found to be significantly potent in inhibiting cancer cell growth.

• 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 ${\mu}M$.

• Horticultural Science & Technology
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• v.28 no.6
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• pp.921-927
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• 2010

The objective of this study was to improve the breeding efficiency and consumption of red onion by analysis of chemical components. The red cultivar S&P5294 ($52.9mg{\cdot}g^{-1}$ F.W.) resulted in the highest sugar content, and sweetness whereas 'Redprime' had the lowest. For the pyruvic acid content the cultivar 'Redsun' showed the highest value, followed by 'Sunpower' (yellow onion) and S&P7270. Breeding lines had higher sugar content and sweetness than 'Redprime' and 'Sunpower', while they had less pyruvic acid value than 'Redsun' and 'Sunpower'. The the same trend was verified for the total phenol and total flavonoid, of which breeding lines were found to have more content than 'Redprime' or 'Sunpower'. Three major flavonoids, rutin (quercetin glycoside), myricetin, and quercetin, were identified and quantified whereas kaempferol was not detected in all cultivars. Rutin was the major flavonoid present in all cultivars (136.9 to $169.9{\mu}g{\cdot}g^{-1}$ F.W.), followed by quercetin (62.5 to $135.7{\mu}g{\cdot}g^{-1}$ F.W.). Relatively smaller amount of myricetin (11.2 to $16.1{\mu}g{\cdot}g^{-1}$ F.W.) was also detected. Among nine cultivars, 'Redsun' exhibited significantly ($p$ < 0.05) higher content of quercetin and rutin (135.7 and $169.9{\mu}g{\cdot}g^{-1}$ F.W., respectively), and S&P5296 had the highest content of myricetin($16.1{\mu}g{\cdot}g^{-1}$ F.W.). Breeding lines had more quercetin, rutin and myricetin contents than the cultivars 'Redprime' and 'Sunpower'. Hampyeong had the highest content for total phenol and total flavonoid, followed by Andong and Changyeong whereas Changyeong had the highest value for rutin, myricetin and quercetin followed by Hampyeong and Andong. Among red onion cultivars, 'Redsun' showed the highest value for anthocyanin, followed by S&P5295 and S&P5296, which the cultivar 'Redprime' had significantly (p<0.05) lower content(35.5 mg%).