• Proceedings of the PSK Conference
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• 2003.04a
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• pp.211.1-211.1
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• 2003

There are now increasing evidences that free radicals and reactive oxygen species are involved in a variety of pathological events. Flavonoids. a group of polypenolic compounds, are widespread in the human food supply. This study was carried out to investigate the antioxidant activity of these compounds. myriceitn and (+)-catechin on B 16Fl0. murine melanoma cell line in oxidative stress. Oxidative stress was induced by exposure to hydrogen peroxide. (omitted)

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.258.3-258.3
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• 2003

The Seeds of Astragalus sinicus(Leguminosae) is used for the treatment of excretion of urine, circulation of blood and the throat inflammation in Korean traditional medicine. Eight flavonoids were isolated from 80％ Acetone extracts. The structure were elucidated as Quercetin 3-O-${\beta}$-D-Xylopyranosyl-(1\longrightarrow2)-${\beta}$-D-galactopyranoside, ampelopsin and myricetin by phytochemical and spectral evidences. The other compounds are understudied by 2D-NMR.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.144.2-145
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• 2003

Reactive Oxygen Species (ROS) are produced during normal cellular function. ROS are very transient species due to their high chemical reactivity that leads to lipid peroxidation and oxidation of some enzyme, massive protein oxidation and degradation. Under normal conditions, antioxidant are substances that either directly or indirectly protect cells against adverse effects of ROS. Several biologically important compounds have been reported to have antioxidant functions. These incluce vitamin C, vitamin E, GSH, flavonoids. superoxidee dismutase(SOD), glutathione peroxidase(GPX) and catalase(CAT). (omitted)

• Journal of Applied Biological Chemistry
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• v.52 no.1
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• pp.15-20
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• 2009

Poplar contains various flavonoids including naringenin, kaempferol, myricetin, apigenin, luteolin, rhamnetin, and quercetin. These flavonoids are synthesized from naringenin with various enzymes. However, none of genes from poplar involved in flavonoid biosynthesis have been biochemically characterized. We cloned PFNS I-1 from Populus deltoids by RT-PCR method. The open reading frame of PFNS I-1 consisted of 1,017-bp and it showed high similarity with other FNS genes. The purified recombinant PFNS I-1, expressed in Escherichia coli, catalyzed the reaction from flavanone (naringenin) to flavone (apigenin). The reaction of PFNS I-1 was enhanced by cofactors such as oxoglutarate, $Fe^{2+}$, ascorbate and catalase. Thus, it is concluded that PFNS N-1 encodes a flavone synthase I.

• YAKHAK HOEJI
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• v.59 no.3
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• pp.107-112
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• 2015

Blueberries (Ericaceae) are cultivated worldwide, and are used not only as foodstuff but also for relievement of eyestrain. Bluberry species representatively includes highbush blueberry (V. corymbosum L.), lowbush blueberry (V. angustifolium $A_{IT}$.), rabbiteye blueberry (V. ashei $R_{EADE}$), and bilberry blueberry (V. myrtillus L.). All of these species contain large amounts of phenolics and anthocyanins. In this regard, we isolated six compounds from Korea cultivated blueberry and identified as 3-O-caffeoylquinic acid (1), 5-O-caffeoylquinic acid (2), myricetin-3-O-${\beta}$-D-galactoside (3), quercetin-3-O-rutinoside (4), ethyl-3-O-caffeoylquinic acid ester (5), ethyl-5-O-caffeoyl quinic acid ester (6) by $^1H$-NMR, $^{13}C$-NMR and MS. Anti-oxidative activities of six compounds were verified by anti-oxidant assay such as DPPH, ABTS and Hypoxanthine/xanthine oxidase system. And then, anti-oxidant activities of Korea blueberry and Canadian were compared with each other. These results support that Korean blueberry has also the possibility to be potential supplementary material as healthy food like Canadian blueberry. Therefore, Korean blueberry can be used as a substitute of Canadian blueberry.

• Korean Journal of Food Science and Technology
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• v.52 no.3
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• pp.205-211
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• 2020

In this study, fruit phenolics were investigated with using LC/MS and HPLC analysis in order to compare the differences between domestic ('Campbell Early', 'Kyoho', 'Heukbosuk', and 'Hongju SDS') and imported ('Crimson SDS' and 'Thomson SDS') grapes. In the case of fruit characteristics, imported grape 'Crimson SDS' and 'Thompson SDS', had lighter skin weight (300-350 mg/berry) and hard flesh (5.2-5.6 kg·f) than domestic grape cultivar. The phenolic compound contents of 'Crimson SDS' skin was higher, but resveratrol (25-29 mg/kg), quercetin (350-380 mg/kg), and myricetin (31-32 mg/kg) contents were similar in to those of 'Hongju SDS'. The anthocyanin content was different from differed between grape cultivars. 'Hongju SDS' grape was showed higher in Delphinidin-3-glucose (D3G) levels, and 'Crimson SDS' was showed higher in Peonidin-3-glucoside (P3G) levels. The contents of phenolic compounds were investigated differently for each grape berry part. Catechin, epicatechin, procyanidin B1, and B2 were found in grape seeds.

• Bulletin of the Korean Chemical Society
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• v.29 no.7
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• pp.1311-1314
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• 2008

Bacillus halodurans O-methyltransferase (BhOMT) is an S-adenosylmethionine dependent methyltransferase. In our previous study, three dimensional structure of the BhOMT has been determined by comparative homology modeling and automated docking study showed that two hydroxyl groups at 3'- and 4'-position in Bring and structural rigidity of C-ring resulting from the double bond characters between C2 and C3 of flavonoid, were key factors for interaction with BhOMT. In the present study, BhOMT was cloned and expressed. Binding assay was performed on purified BhOMT using fluorescence experiments and binding affinity of luteolin, quercetin, fisetin, and myricetin were measured in the range of $10^7$. Fluorescence quenching experiments indicated that divalent cation plays a critical role on the metal-mediated electrostatic interactions between flavonoid and substrate binding site of BhOMT. Fluorescence study confirmed successfully the data obtained from the docking study and these results imply that hydroxyl group at 7-position of luteolin, quercetin, fisetin, and myricetin forms a stable hydrogen bonding with K211 and carboxyl oxygen of C-ring forms a stable hydrogen bonding with R170. Hydroxyl group at 3'-and 4'-position in the B-ring also has strong $Ca^{2+}$ mediated electrostatic interactions with BhOMT.

• Journal of Life Science
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• v.19 no.8
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• pp.1125-1131
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• 2009

The antimicrobial activities of Helicobacter pylori as a functional food source with water and 60% ethanol extracts from Rododendron mucronulatum Turcz. flowers were examined. The total phenol content of 60% ethanol extracts (30.6${\pm}$0.14 mg/g) from Rododendron mucronulatum Turcz. flowers was higher than that of water extracts (23.2${\pm}$0.21 mg/g). The inhibitory activities of Rododendron mucronulatum Turcz. extracts on H. pylori was determined to clear zone of 15 mm in 80% ethanol extracts. Purification of inhibitory compounds was carried out in Sephadex LH-20 and MCI-gel CHP-20 column chromatography using a gradient procedure, with increasing ethanol(0${\rightarrow}$100%) in $H_2O$. The chemical structure of the purified inhibitory compounds of H. pylori was identified to be quercitrin (quercetin-3-O- rhamnopyranoside), myricitrin (myricetin-3-O-rhamnopyranoside), quercetin by FAB-MS, NMR and IR spectra.

• Journal of Korea Foresty Energy
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• v.21 no.1
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• pp.56-64
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• 2002

2kg of the dried leaves of Thuja orientalis Linnaeus were ground, extracted with acetone-$H_2O$(7:3, v/v), concentrated, and fractionated with a series of hexane, $CH_2C1_2$ EtOAc and water on a separators funnel. Each fraction was freeze dried to give dark-brown powder and a EtOAc soluble portion. of the powder was chromatographed on a Sephadex LH-20 column using a series of aqueous methanol and ethanol-hexane mixture as eluents. Spectrometric analyses such as NMR and FAB-MS including TLC were performed to characterize the structures of isolated compounds. The leave of Thuja orientalis Linnaeus contained a large amount of flavononol derivatives such as quercetin-3-O-$\alpha$-L-rhamnopyranoside and myricetin-3-O-$\alpha$-L-rhamnopyranoside in addition to a small amount of flavan compounds such as (+)-catechin and (+)-gallocatechin. The antioxidative activities of each fractions and isolated compounds were done by DPPH radical scavenging test, and all of them were indicated strong antioxidative activities.

• Korean Journal of Pharmacognosy
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• v.46 no.2
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• pp.105-108
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• 2015

To establish the anti-diabetic(α-glucosidase inhibitory) activity of D. lotus leaf extract, isolate and identify the constituents responsible for the activity. The methanolic extract of leaves was partitioned between water, n-butanol and ethyl acetate. Bio-assay guided fractionation, based on inhibition of ;${\alpha}$-glucosidase, allowed isolation and identification of the active components. Liquid chromatography/mass spectrometry(LC/MS), ¹ H-NMR and ¹³ C-NMR spectra analyses demonstrated that the active compound was myricetin-3-O-;${\alpha}$-L-rhamnoside(1). Compound 1 demonstrated a strong inhibition on the α-glucosidase, in vitro and ;${\alpha}$-glucosidase inhibitory value was calculated as 98.08%, when that of a reference drug, acarbose was estimated as 83.03%. The present study indicates compound 1 could be considered as an ;${\alpha}$-glucosidase inhibitor and developed as an important antidiabetes agent for type II diabetes therapy.