• 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.

• Advances in Traditional Medicine
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• v.9 no.3
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• pp.252-258
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• 2009

Shade-dried flowers of Sarcostemma brevistigma Wight Syn (SBF) belonging to Asclepiadaceae yielded a rare flavonol glycoside viz., Quercetin 5a prenyl, 3-O-glucosyl, 7-O-(4c-p-coumaroyl) neohesperidoside which were characterized based on chemical and spectral (including 2D NMR) studies. The ethyl acetate fraction of alcoholic concentrate (test sample) of flowers of this plant (SBF) was evaluated for its hepatoprotective and inhibition of lipid peroxidation activities to investigate the scientific basis of the traditional uses. The oral administration in varying doses viz., 125 and 250 mg/kg of aqueous suspension of SBF to rats for 7 days produced significant (P < 0.01) hepatoprotective effect comparable to that of standard drug silymarin. The SBF afforded good hepatoprotection against $CCl_4$ induced elevation levels of serum marker enzymes, serum bilirubin and liver weight. The free radical scavenging effects of SBF and flavonol glycoside (SA) were assigned by $Fe^{2+}$/ascorbate induction method (in vitro), which revealed the inhibition of lipid peroxidation. The SBF and SA showed prominent anti-lipid peroxidation activity ($IC_{50}$ about $\sim$180 mg/ml and 11.0 mg/ml respectively), which was comparable to standard drug curcumin ($IC_{50}$ about $\sim$8.25 mg/ml). Thus the hepatoprotective activity of SB could be correlated to the free radical scavenging property of the flavonol glycoside.

• Applied Biological Chemistry
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• v.42 no.2
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• pp.166-169
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• 1999

The repeated silica gel colum chromatographies of n-BuOH fraction obtained from MeOH extracts of Eucommia ulmoides leaves led to isolation of a flavonoid-glycoside inhibiting monoamine oxidase B activity. Its chemical structure was determined to be $3-O-[{\beta}-D-glucopyranosyl\;(1{\rightarrow}2)\;{\beta}-D-xylopyranosyl]$ quercetin through interpretation of spectral data and adaptation of acid hydrolysis. The $IC_{50}$ value of this compound in rat brain mitochondrial MAO-B inhibitory activity was evaluated to be $8.05\;{\mu}mol/l$.

• YAKHAK HOEJI
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• v.40 no.4
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• pp.394-399
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• 1996

As a series of the studies on the specific and indigenous plants of Mt. Halla, the constituents from stem of Rhamnus taquetii (Rhamnaceae) were investigated. From the water fraction of the MeOH extract, a new flavonol glycoside, kaempferide-3-O-${\alpha}$-L-rhamnopyranosyl(1->3)-${\alpha}$-L-rhamnopyranosyl(1-6)-${\beta}$-D-galactopyranoside, was isolated with three known compounds, quercetin, quercetin-3-methylether, kaempferol, by column chromatographic separation using Amberlite XAD-2, ODS-gel and Sephadex LH-20 and elucidated physico-chemical evidences($^1H-NMR,\;^{13}C-NMR$,IR, EI-Mass, FAB-Mass, and G.C.),respectively.

• Korean Journal of Pharmacognosy
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• v.33 no.3 s.130
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• pp.194-199
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• 2002

The radix and folium of Eucommia ulmoides(Eucommiaceae) has been used for backache, atrophy of the leg and knee, enuresis, hypertension. In order to evaluate to quality of folium, we have been isolated a main compound as a standard compound, which was elucidated $quercetin-3-O-{\beta}-D-xylopyranosyl(l{\rightarrow}2)-{\beta}-D-glucopyranoside$ through it's physicochemical data and IR, FAB-Mass, $^{13}C-NMR$ and $^{1}H-NMR$ analysis. It was analyzed by HPLC system using 17% $CH_3CN$ as a solvent system. The amount of $quercetin-3-O-{\beta}-D-xylopyranosyl(l{\rightarrow}2)-{\beta}-D-glucopyranoside$ from Eucommiae folium was in the range of $0.056{\pm}0.022$ mg(n=7) and also from the results of analysis through seasonal variation$(June{\sim}October)$ September and October have been evaluated to be very high in it's content.

• Biomolecules & Therapeutics
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• v.24 no.6
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• pp.610-615
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• 2016

Quercetin, a flavonol, has been reported to exhibit a wide range of biological properties including anti-oxidant and anti-inflammatory activities. However, pharmacological properties of quercetin-3-O-${\beta}$-D-glucuronide (QG), a glycoside derivative of quercetin, have not been extensively examined. The objective of this study is to elucidate the anti-inflammatory property and underlying mechanism of QG in lipopolysaccharide (LPS)-challenged RAW264.7 macrophage cells in comparison with quercetin. QG significantly suppressed LPS-induced extracellular secretion of pro-inflammatory mediators such as nitric oxide (NO) and $PGE_2$, and pro-inflammatory protein expressions of iNOS and COX-2. To elucidate the underlying mechanism of the anti-inflammatory property of QG, involvement of MAPK signaling pathways was examined. QG significantly attenuated LPS-induced activation of JNK and ERK in concentration-dependent manners with a negligible effect on p38. In conclusion, the present study demonstrates QG exerts anti-inflammatory activity through the suppression of JNK and ERK signaling pathways in LPS-challenged RAW264.7 macrophage cells.

• Korean Journal of Pharmacognosy
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• v.43 no.3
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• pp.206-212
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• 2012

Ten flavonol glycosides were isolated from the EtOAc fraction of the MeOH extract of Metaplexis japonica Makino. Structures of the flavonoids were elucidated on the basis of spectroscopic data and comparison with literature values. The flavonoids were found to be mostly common flavonol 3-glycosides. It is of interest that the sacchaide parts of the isolates were pairs of arabinosides, glucosides, galactosides, rutinosides and robinobiosides of kaempferol and quercetin. All of these compounds were isolated for the first time from this plant.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.16 no.1
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• pp.1-17
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• 1990

The major flavonoid component of Ginseng leaf is trifolin, a glycoside of kaempferol. To evaluate the antioxidative properties of trifolin and kaempferol on cellular membranes, we compared them with the other flavonoids through the 102-Induced photohemolysis of rabbit erythrocytes. All the flavonoid aglycones including kaempferol, quercetin and baicalein protected effectively the cells from the 102-caused damage in a dose- dependent manner, by scavenging 102 and free radicals in the cellular membranes. The solubilization of the flavonoid aglycones into micelles or erythrocyte membranes was deduced from spectro-photometric and microscopic observations. The flavonoid glycosides were not protective or less protective than their corresponding aglycones, and trifolin was the only glycoside that exhibited a solubilization into the membranes and a significant protection against the photohemolysis. We also tested some phenolic compounds contained in Ginseng, and found that they did not prevent the photohemolysis so effectively as kaempferol or trifolin.

• Korean Journal of Pharmacognosy
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• v.21 no.2
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• pp.111-120
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• 1990

Five biflavones and sevenflavonolglycosideswereisolatedfromtheleaves of Ginkgo biloba. They were sciadopitysin(1), ginkgetin(2), isoginkgetin(3), bilobetin(4), amentoflavone(5), kaempferol 3-O-[$6'-O-{\rho}-coumaroyl-{\beta}-_D-glucopyranosyl(1{\rightarrow}2)-{\alpha}-_Lrhamnopyranoside$](6), quercetin 3-O-[$6'-O-{\rho}-coumaroyl-{\beta}-_D-glucopyranosyl(1{\rightarrow}2)-{\alpha}-_Lrhamnopyranoside$](8), rutinosides of kaempferol(7), isorhamnetin(9), quercetin(10), laricitrin(11), and kaempferol 3-O-($2',6'-{\alpha}-_L-dirhamnopyranosyl-{\beta}-_{D}-glucopyranoside$)(12). The structures were established by spectroscopic and chemical methods.

• YAKHAK HOEJI
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• v.38 no.4
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• pp.469-475
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• 1994

As the continued studies for Korean cultivated rhubarb, MeOH extract of the leaves was fractionated with ether, ethylacetate, and n-butanol. From the ethyl acetate fraction of MeOH extract, one flavone glycoside, apigenin-8-${\beta}$-D-glucopyranoside(vitexin, $C_{21}H_{20}O_{10}$) and from the n-BuOH fraction of MeOH extract, two flavonol glycosids, kaempferol-3-O-(2,6-di-O-rhamnopyranosyl)-${\beta}$-D-galactopyranoside$(C_{33}H_{40}O_{19})$and quercetin-3-O-rutinoside(rutin, $C_{27}H_{30}O_{16}$) were isolated and identified through the physico-chemical properties and spectroscopic evidences(UV, IR, NMR, Mass) respectively.