20(S)-ginsenoside Rh2, a newly identified active ingredient of ginseng, inhibits NMDA receptors in cultured rat hippocampal neurons.
Most herbal medicines that are orally administrated have been known to be metabolized before they are absorbed from the gastrointestinal tract. We, therefore, examined the effects of 20(S)-ginsenosides Rb1, Rg1 and Rg3, the three most commonly studied ginsenosides in the central nervous system, and their main metabolites on NMDA receptors using fura-2-based digital imaging and perforated whole-cell patch-clamp techniques. Among the nine ginsenosides tested, 20(S)-ginsenoside Rh2 (20(S)-Rh2) along with 20(S)-ginsenoside Rg3 (20(S)-Rg3) produced the highest inhibitory effect in cultured hippocampal neurons. Although 20(S)-Rg3 and 20(S)-Rh2 selectively targeted NMDA receptors with similar potency, they produced additive effects and seemed to modulate different NMDA receptor regulatory sites. As a competitive antagonist, 20(S)-Rh2 seems to inhibit the receptor via its interaction with polyamine-binding sites, and 20(S)-Rg3 does so using glycine-binding sites. Therefore, these results suggest that the treatment of 20(S)-Rh2, a newly identified active ingredient of ginseng, might be a novel preventive candidate in treating neurodegenerative disorders.
Lee
Eunyoung
E
Biomedical Research Center, Korea Institute of Science and Technology (KIST), 39-1 Hawholgok-dong Sungbuk-gu, Seoul 136-791, Republic of Korea.
Kim
Sunoh
S
Chung
Kwang Chul
KC
Choo
Min-Kyung
MK
Kim
Dong-Hyun
DH
Nam
Ghilsoo
G
Rhim
Hyewhon
H
D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005333:Fetus; D036145:Ginsenosides / Q000737:chemistry / Q000494:pharmacology*; D006624:Hippocampus; D008564:Membrane Potentials / Q000187:drug effects; D015394:Molecular Structure; D016202:N-Methylaspartate / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D005894:Panax / Q000737:chemistry*; D011073:Polyamines / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists / Q000037:antagonists & inhibitors* / Q000502:physiology; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
D036145:Ginsenosides; D011073:Polyamines; D016194:Receptors, N-Methyl-D-Aspartate; C097367:ginsenoside Rg3; D016202:N-Methylaspartate; C055305:ginsenoside Rh2; D002118:Calcium