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Differential Effects of Quercetin and Quercetin Glycosides on Human α7 Nicotinic Acetylcholine Receptor-Mediated Ion Currents.

Lee BH, Choi SH, Kim HJ, Jung SW, Hwang SH, Pyo MK, Rhim H, Kim HC, Kim HK, Lee SM, Nah SY - Biomol Ther (Seoul) (2016)

Bottom Line: Quercetin is a flavonoid usually found in fruits and vegetables.Quercetin glycosides mediated an inhibition of IACh, which increased when they were pre-applied and the inhibitory effects were concentration dependent.These results show that quercetin and quercetin glycosides regulate the α7 nAChR in a differential manner.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, College of Veterinary Medicine and BioMolecular Informatics Center, Konkuk University, Seoul 05029, Republic of Korea.

ABSTRACT
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 α7 nicotinic acetylcholine receptor (α7 nAChR)-mediated ion currents. However, the role of the carbohydrates attached to quercetin in the regulation of α7 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 (IACh) in Xenopus oocytes expressing the α7 nAChR. IACh was measured with a two-electrode voltage clamp technique. In oocytes injected with α7 nAChR copy RNA, quercetin enhanced IACh, whereas quercetin glycosides inhibited IACh. Quercetin glycosides mediated an inhibition of IACh, which increased when they were pre-applied and the inhibitory effects were concentration dependent. The order of IACh inhibition by quercetin glycosides was Rutin≥Rham1>Rham2. Quercetin glycosides-mediated IACh enhancement was not affected by ACh concentration and appeared voltage-independent. Furthermore, quercetin-mediated IACh inhibition can be attenuated when quercetin is co-applied with Rham1 and Rutin, indicating that quercetin glycosides could interfere with quercetin-mediated α7 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 α7 nAChR in a differential manner.

No MeSH data available.


Chemical structures of quercetin and its glycosides. (A) Quercetin, (B) quercetin-3-O-rhamnoside (Rham1), (C) quercetin-3-O-rutinoside (Rutin), and (D) quercetin-3-(2G-rhamnosylrutinoside) (Rham2).
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f1-bt-24-410: Chemical structures of quercetin and its glycosides. (A) Quercetin, (B) quercetin-3-O-rhamnoside (Rham1), (C) quercetin-3-O-rutinoside (Rutin), and (D) quercetin-3-(2G-rhamnosylrutinoside) (Rham2).

Mentions: Human wild-type α7 nAChR cDNA was kindly provided by Dr. S. Heinemann (Salk Institute, California, USA). Quercetin (Fig. 1) and all other reagents were purchased from Sigma-Aldrich (St. Louis, MO, USA).


Differential Effects of Quercetin and Quercetin Glycosides on Human α7 Nicotinic Acetylcholine Receptor-Mediated Ion Currents.

Lee BH, Choi SH, Kim HJ, Jung SW, Hwang SH, Pyo MK, Rhim H, Kim HC, Kim HK, Lee SM, Nah SY - Biomol Ther (Seoul) (2016)

Chemical structures of quercetin and its glycosides. (A) Quercetin, (B) quercetin-3-O-rhamnoside (Rham1), (C) quercetin-3-O-rutinoside (Rutin), and (D) quercetin-3-(2G-rhamnosylrutinoside) (Rham2).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4930285&req=5

f1-bt-24-410: Chemical structures of quercetin and its glycosides. (A) Quercetin, (B) quercetin-3-O-rhamnoside (Rham1), (C) quercetin-3-O-rutinoside (Rutin), and (D) quercetin-3-(2G-rhamnosylrutinoside) (Rham2).
Mentions: Human wild-type α7 nAChR cDNA was kindly provided by Dr. S. Heinemann (Salk Institute, California, USA). Quercetin (Fig. 1) and all other reagents were purchased from Sigma-Aldrich (St. Louis, MO, USA).

Bottom Line: Quercetin is a flavonoid usually found in fruits and vegetables.Quercetin glycosides mediated an inhibition of IACh, which increased when they were pre-applied and the inhibitory effects were concentration dependent.These results show that quercetin and quercetin glycosides regulate the α7 nAChR in a differential manner.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology, College of Veterinary Medicine and BioMolecular Informatics Center, Konkuk University, Seoul 05029, Republic of Korea.

ABSTRACT
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 α7 nicotinic acetylcholine receptor (α7 nAChR)-mediated ion currents. However, the role of the carbohydrates attached to quercetin in the regulation of α7 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 (IACh) in Xenopus oocytes expressing the α7 nAChR. IACh was measured with a two-electrode voltage clamp technique. In oocytes injected with α7 nAChR copy RNA, quercetin enhanced IACh, whereas quercetin glycosides inhibited IACh. Quercetin glycosides mediated an inhibition of IACh, which increased when they were pre-applied and the inhibitory effects were concentration dependent. The order of IACh inhibition by quercetin glycosides was Rutin≥Rham1>Rham2. Quercetin glycosides-mediated IACh enhancement was not affected by ACh concentration and appeared voltage-independent. Furthermore, quercetin-mediated IACh inhibition can be attenuated when quercetin is co-applied with Rham1 and Rutin, indicating that quercetin glycosides could interfere with quercetin-mediated α7 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 α7 nAChR in a differential manner.

No MeSH data available.