Stereospecificity of Ginsenoside Rg3 Action on Ion Channels
2004; Springer Science+Business Media; Volume: 18; Issue: 3 Linguagem: Inglês
10.1016/s1016-8478(23)13128-1
ISSN0219-1032
AutoresSang Min Jeong, Jun‐Ho Lee, Jong‐Hoon Kim, Byung-Hwan Lee, In‐Soo Yoon, Joon‐Hee Lee, Dong‐Hyun Kim, Hyewhon Rhim, Yangmee Kim, Seung‐Yeol Nah,
Tópico(s)Pharmacological Effects of Natural Compounds
ResumoGinsenosides, active ingredients of Panax ginseng, exist as stereoisomers depending on the position of the hydroxyl group on carbon-20; i.e. 20(R)-ginsenoside and 20(S)-ginsenoside are epimers. We have shown previously that the mixture of 20(R)- and 20(S)-ginsenosides regulates ion channel activity. However, it was not clear which epimer was responsible. We investigated the structure-activity relationship of the ginsenoside Rg3 stereoisomers, 20-R-protopanaxatriol-3-[O-β-D-glucopyranosyl (1→2)-β-glucopyranoside], (20(R)-Rg3) and 20-S-proto-panaxatriol-3-[O-β-D-glucopyranosyl (1→2)-β-glucopyr-anoside], (20(S)-Rg3) in regulating voltage-dependent Ca2+, K+ or Na+ channel currents and 5-HT3A and α3β4 nicotinic acetylcholine (nACh) receptor channel currents expressed in Xenopus oocytes. 20(S)-Rg3 but not 20(R)-Rg3 inhibited the Ca2+, K+ and Na+ channel currents in a dose- and voltage-dependent manner. The fact that only 20(S)-Rg3 is active indicates that its hydroxyl group may be geometrically better aligned with the hydroxyl acceptor group in the ion channels than that of 20(R)-Rg3. However, both Rg3 stereoisomers inhibited 5-HT3A and α3β4 nACh receptor channel currents. These results indicate that the selectivity of action of the Rg3 stereoisomers differs between voltage-dependent and ligand-gated ion channels.
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