• Natural Product Sciences
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• v.11 no.2
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• pp.75-78
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• 2005

A new acetophenone named rumexin $(3-hydroxy-5-methyl-4-O-{\beta}-D-glucopyranosyl\;acetophenone)$ was isolated from methanolic extract of Rumex aquatica together with eight known compounds, $quercetin-3-O-{\beta}-D-glucuropyranoside$, $musizin-8-O-{\beta}-D-glucopyranoside$, $quercetin-3-O-{\alpha}-L-rhamnoside$, $emodin-8-O-{\beta}- D-glucopyranoside$, caffeic acid, $1-O-caffeoyl-{\beta}-D-glucopyranoside$, 1-methyl caffeic acid, $kaempferol-3-O-{\beta}-D-glucuropyranoside$. All of the above compounds were isolated from Rumex aquatica for the first time, and structures of compounds were established by spectroscopic means.

• YAKHAK HOEJI
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• v.40 no.2
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• pp.170-176
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• 1996

A chemical examination of the aerial parts of Euphorbia pekinensis $R_{UPRECHT}$. (Euphorbiaceae) has led to the isolation of seven hydrolyzable tannins and ten fl avonoid glycosides. The former ones have been identified as gallic acid, methylgallate, 3-O-galloyl shikimic acid, 1,3,4,6-tetra-O-galloyl-${\beta}-_D$-glucose, 1,2,3,4,6-penta-O-galloyl-${\beta}-_D$-glucose, corilagin, geraniin and the latter ones as isoquercitrin, quercitrin, astragalin, afzelin, prunin, rutin, kaempferol-3-O-rutinoside, quercetin-3-O-(2"-O-galloyl)-${\beta}-_D$-glucoside and quercetin-3-O-(2"-O-galloyl)-${\alpha}-_L$-rhamnoside on the basis of chemical and spectroscopic evidence.

• Biomolecules & Therapeutics
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• v.24 no.4
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• pp.410-417
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• 2016

Quercetin is a flavonoid usually found in fruits and vegetables. Aside from its antioxidative effects, quercetin, like other flavonoids, has a various neuropharmacological actions. Quercetin-3-O-rhamnoside (Rham1), quercetin-3-O-rutinoside (Rutin), and quercetin-3-(2(G)-rhamnosylrutinoside (Rham2) are mono-, di-, and tri-glycosylated forms of quercetin, respectively. In a previous study, we showed that quercetin can enhance ${\alpha}7$ nicotinic acetylcholine receptor (${\alpha}7$ nAChR)-mediated ion currents. However, the role of the carbohydrates attached to quercetin in the regulation of ${\alpha}7$ nAChR channel activity has not been determined. In the present study, we investigated the effects of quercetin glycosides on the acetylcholine induced peak inward current ($I_{ACh}$) in Xenopus oocytes expressing the ${\alpha}7$ nAChR. $I_{ACh}$ was measured with a two-electrode voltage clamp technique. In oocytes injected with ${\alpha}7$ nAChR copy RNA, quercetin enhanced $I_{ACh}$, whereas quercetin glycosides inhibited $I_{ACh}$. Quercetin glycosides mediated an inhibition of $I_{ACh}$, which increased when they were pre-applied and the inhibitory effects were concentration dependent. The order of $I_{ACh}$ inhibition by quercetin glycosides was Rutin${\geq}$Rham1>Rham2. Quercetin glycosides-mediated $I_{ACh}$ enhancement was not affected by ACh concentration and appeared voltage-independent. Furthermore, quercetin-mediated $I_{ACh}$ inhibition can be attenuated when quercetin is co-applied with Rham1 and Rutin, indicating that quercetin glycosides could interfere with quercetin-mediated ${\alpha}7$ nAChR regulation and that the number of carbohydrates in the quercetin glycoside plays a key role in the interruption of quercetin action. These results show that quercetin and quercetin glycosides regulate the ${\alpha}7$ nAChR in a differential manner.

• Natural Product Sciences
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• v.4 no.1
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• pp.9-14
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• 1998

Jaceidin, Jaceidin-7-O-methylether and quercetin were isolated from-Juniperus phoenicea L. alcoholic extract, however, Sequoiaflavone was isolated from Cupressus semperiverns L. In addition, the alcoholic extracts of both plants were found to contain also kaempferol-3-O-rhamnoside, quercetrin, myricitrin, cupressuflavone. The chemical identities of the isolated compounds were established using UV, IR, $^1H-and\;^{13}C-NMR$ spectroscopy.

• Natural Product Sciences
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• v.8 no.1
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• pp.16-17
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• 2002

The flavonoids kaempferol, quercetin, myrecetin, kaempferol-3-O-rhamnoside and quercetrin has been isolated from the leaves of C. tamala and their structures were established by spectral analysis and direct comparison with authentic samples. This is the first report of occurrence of these compounds from C. tamala.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.34 no.3
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• pp.233-244
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• 2008

In this study, the antioxidative effects, inhibitory effects on elastase and tyrosinase, and component analysis of Psidium guajava leaf extracts were investigated. The free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scavenging activities $(FSC_{50})$ of extract/fractions of Psidium guajava leaf were in the order: 50% ethanol extract $(7.05{\mu}g/mL)$ < ethyl acetate fraction $(3.36{\mu}g/mL)$ < deglycosylated flavonoid aglycone fraction $(3.24{\mu}g/mL)$. Reactive oxygen species (ROS) scavenging activities $(OSC_{50})$ of some Psidium guajava leaf extracts on ROS generated in $Fe^{3+}-EDTA/H_2O_2$ system were investigated using the luminol-dependent chemiluminescence assay. The order of ROS scavenging activities were 50% ethanol extract $(OSC_{50},\;2.17{\mu}g/mL)$ < ethyl acetate fraction $(0.64{\mu}g/mL)$ < deglycosylated flavonoid aglycone fraction $(3.39{\mu}g/mL)$. Aglycone fraction showed the most prominent ROS scavenging activity. The protective effects of extract/fractions of Psidium guajava leaf on the rose-bengal sensitized photohemolysis of human erythrocytes were investigated. The Psidium guajava leaf extracts suppressed photohemolysis in a concentration dependent manner $(1{\sim}10{\mu}g/mL)$, particularly deglycosylated flavonoid aglycone fraction exhibited the most prominent celluar protective effect ${\tau}_{50}\;107.5min\;at\;1{\mu}g/mL)$. Aglycone fraction obtained from the deglycosylation reaction of ethyl acetate fraction among the Psidium guajava leaf extracts, showed 1 band in TLC and 1 peak in HPLC experiments (360 nm). One component was identified as quercetin. TLC chromatogram of ethyl acetate fraction of Psidium guajava leaf extract revealed 5 bands and HPLC chromatogram showed 5 peaks, which were identified as quercetin 3-O-gentobioside (10.32%) , quercetin 3-O-${\beta}$-D-glucoside (isoquercitin, 13.30%), quercetin 3-O-${\beta}$-D-galactoside (hyperin, 11.34%), quercetin 3-O-${\alpha}$-L-arabinoside (guajavarin, 19.70%), quercetin 3-O-${\beta}$-L-rhamnoside (quercitrin, 45.33%) in the order of elution time. The inhibitory effect of Psidium guajava leaf extracts on tyrosinase were investigated to assess their whitening efficacy. Finally, their anti-elastase activities were measured to predict the anti-wrinkle efficacy in the human skin. Inhibitory effects $(IC_{50})$ on tyrosinase of some Psidium guajava leaf extracts was 50% ethanol extract $(149.67{\mu}g/mL)$ < ethylacetate fraction $(30.67{\mu}g/mL)$ < deglycosylated aglycone fraction $(17.10{\mu}g/mL)$. Inhibitory effects $(IC_{50})$ on elastase of some Psidium guajava leaf extracts was 50% ethanol extract $(6.60{\mu}g/mL)$ < deglycosylated aglycone fraction $(5.66{\mu}g/mL)$ < ethylacetate fraction $(3.44{\mu}g/mL)$. These results indicate that extract/fractions of Psidium guajava leaf can function as antioxidants in bioloigcal systems, particularly skin exposed to UV radiation by scavenging $^1O_2$ and other ROS, and protect cellular membranes against ROS. And component analysis of Psidium guajava leaf extract and inhibitory activity on elastase of the aglycone fraction could be applicable to new functional cosmetics for smoothing wrinkles.

• Natural Product Sciences
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• v.11 no.4
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• pp.199-206
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• 2005

Investigation of M. peregrina aerial parts revealed the isolation and identification of 4-flavonoidal compounds, quercetin, quercetin-3-0-rutinoside (rutin), chrysoeriol-7-0-rhamnoside 6,8,3',5'-tetramethoxy apigenin. The compounds were identified by TLC, PC, MS, and $H^1-NMR$. The fatty acids and unsaponifiable matter were studied. The $LD_{50}$ for M. peregrina was 113.4 mg/100g b.wt. Repeated intraperitoneal injection of 1/20 and 1/10 $LD_{50}$ (5.67 mg and 11.34 mg/100g b.wt.) of defatted alcoholic of M. peregrina for 30 days induced significant decrease in serum glucose, liver enzymes and lipid components. M. peregrina administered i.p., 30min prior to carrageenan at the above doses significantly inhibited the rat paw oedema response, In acute pain models, namely, the acetic acid-induced writing and hot-plate assay, M. peregrina exhibited marked analgesic properties. In addition, M. peregrina administered at time of indomethacin injection inhibited the development of gastric lesions in rats.

• The Plant Pathology Journal
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• v.24 no.3
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• pp.322-327
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• 2008

Antifungal activities of natural substrances from Eucalyptus darlympleana, E. globules, E. gunnii and E. unigera were evaluated against postharvest pathogens of kiwifruits, Botrytis cinerea, Botryosphaeria dothidea, and Diaporthe actinidiae, to screen effective natural substances as an alternative to chemical fungicides. Methanol extract of the Eucalyptus trees showed strong antagonistic activity against the pathogenic fungi. Among them, E. unigera and E. darlympleana effectively inhibited mycelial growth of the pathogens. For chemical identification of the antifungal substances, the methanol extract of E. darlympleana leaves was successively partitioned with $CH_2Cl_2$, EtOAc, n-BuOH and $H_2O$. Among the fractions, $CH_2Cl_2$ and n-BuOH showed strong inhibitory activity of mycelial growth of the fungi. Five compounds were isolated from EtOAc and n-BuOH fractions subjected to $SiO_2$ column chromatography. Two phenolic compounds(gallic acid and 3,4-dihydroxybenzoic acid) and three flavonoid compounds(quercetin, quercetin-3-O-$\alpha$-L-rhamnoside, quercetin-3-O-$\beta$-glucoside) were identified by $^1H$-NMR and $^{13}C$-NMR spectroscopy. Among them, only gallic acid was found to be effective in mycelial growth and spore germination of B. cinerea at relatively high concentrations. The results suggest that gallic acid can be a safer and more acceptable alternative to current synthetic fungicides controlling soft rot decay of kiwifruit during postharvest storage.

• Microbiology and Biotechnology Letters
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• v.42 no.1
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• pp.51-57
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• 2014

In this study, the antioxidative effects and component analysis of Polygonum aviculare (P. aviculare) extracts were investigated. The ethyl acetate and the aglycone fraction from P. aviculare extracts were more active than (+)-${\alpha}$-tocopherol and $\small{L}$-ascorbic acid, which are known as strong antioxidants for their antioxidative activity by the DPPH method and chemiluminescence assay. The cellular protective effects of fractions of P. aviculare on the rose-bengal sensitized photohemolysis of human erythrocytes, increased in a concentration dependent manner ($1-10{\mu}l$). In particular, the ethyl acetate fraction at a concentration of $10{\mu}l$ showed the most prominent protective effect among all the extracts (${\tau}_{50}$, 314.70 min). TLC and HPLC chromatogram of the ethyl acetate fraction of P. aviculare extracts revealed 3 main bands (PA8, PA5, PA6) and peaks (peak 1, peak 2, peak 3), which were identified as myricetin-3-O-rhamnoside (myricitrin, PA8, peak 1), quercetin-3-${\alpha}$-rhamnoside (quercitrin, PA6, peak 3) by LC/ESI-MS/MS and $^1H$-NMR respectively. These results indicate that fractions from P. aviculare could be applicable to new functional cosmetics as antioxidants.

• The Korean Journal of Food And Nutrition
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• v.31 no.4
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• pp.464-470
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• 2018

All the parts of the Cedrela sinensis A. Juss., including the seeds, roots, and leaves, have been known to exert medicinal effects. The C. sinensis and its major compound, quercetin, were previously reported to exhibit the anti-inflammatory and anti-oxidative activities. However, the hepatoprotective effects of the C. sinensis leaves against the alcohol-induced oxidative stress in the HepG2 cells have not been studied. In this study, we investigated the antioxidant activities and analyzed the flavonoid contents of the C. sinensis-leaf extract (CE). The total flavonoid contents of the CE is 1,874.5 mg/100 g dry weight (DW), while the total quercetin 3-O-rhamnoside (quercitrin) contents, which was identified as the major flavonol in the CE, is 1,456.0 mg/100 g DW. In the ethanol-stimulated HepG2 cells, the CE effectively prevented the cytotoxic effect and increased the gene expression of the antioxidant enzymes, such as the heme oxygenase-1 (HO-1) and the glutathion peroxide (GPx). The level of the reactive oxygen species (ROS) production was significantly decreased in the CE-treated HepG2 cells. In conclusion, the C. sinensis extract suppressed the alcohol-induced oxidative stress in the HepG2 cells via the induced GPx and HO-1 gene expressions. It is expected the CE positive effects will likely be attributed to the flavonoids, like the quercetin, within the CE.