Properties of ginseng saponin inhibition of catecholamine secretion in bovine adrenal chromaffin cells.
To investigate the relationship between the inhibitory effects of ginseng saponins (ginsenosides) on acetylcholine-evoked secretion of catecholamines and the structures of ginsenosides, we examined the effects of ginsenoside-Rg3 and -Rh2, which are panaxadiol saponins, 20(R)- and 20(S)-ginsenoside-Rg2, which are epimers involving the hydroxyl group at C-20 of sapogenin, and other plant saponins on the acetylcholine-evoked secretion of catecholamines from cultured bovine adrenal chromaffin cells. The ginsenoside-Rg3 (1-100 microM) and -Rh2 (10-100 microM) greatly reduced the acetylcholine-evoked secretion in a concentration-dependent manner comparable to that of ginsenoside-Rg2, a panaxatriol saponin, which was the most potent inhibitor in our previous study. 20(R)- and 20(S)-ginsenoside-Rg2 (1-100 microM) similarly reduced the acetylcholine-evoked secretion. In contrast, saikosaponin-a, glycyrrhizin and the cardiac glycosides (100 nM-100 microM), digitoxin and digoxin, had no significant inhibitory effect on catecholamine secretion. Saikosaponin-c (10-100 microM), however, had an inhibitory effect, which was less than that of ginsenoside-Rg2 and -Rg3. These results strongly suggest that the inhibitory effects of ginsenosides on the acetylcholine-evoked secretion of catecholamines from bovine adrenal chromaffin cells are a unique property of ginseng. Further, the relationship between the inhibitory effects and the structures of ginsenosides is discussed.
Kudo
K
K
Department of Pharmacology, School of Medicine, Iwate Medical University, Morioka, Japan.
Tachikawa
E
E
Kashimoto
T
T
Takahashi
E
E
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D002301:Cardiac Glycosides / Q000494:pharmacology; D002395:Catecholamines / Q000378:metabolism*; D002417:Cattle; D002491:Central Nervous System Agents / Q000737:chemistry / Q000494:pharmacology*; D019439:Chromaffin Cells / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D036145:Ginsenosides; D019695:Glycyrrhizic Acid / Q000494:pharmacology; D009828:Oleanolic Acid / Q000031:analogs & derivatives*; D005894:Panax / Q000737:chemistry*; D010946:Plants, Medicinal; D012502:Sapogenins / Q000494:pharmacology; D012503:Saponins / Q000737:chemistry / Q000494:pharmacology*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D000972:Antineoplastic Agents, Phytogenic; D002301:Cardiac Glycosides; D002395:Catecholamines; D002491:Central Nervous System Agents; D036145:Ginsenosides; D012502:Sapogenins; D012503:Saponins; C097367:ginsenoside Rg3; C026474:ginsenoside Rg2; D019695:Glycyrrhizic Acid; D009828:Oleanolic Acid; C055305:ginsenoside Rh2; C025759:saikosaponin D