Inhibitory Effect of 20(S)-Ginsenoside Rg3 on Human Platelet Aggregation and Intracellular Ca 2+ Levels via Cyclic Adenosine Monophosphate Dependent Manner.

Intracellular Ca2+ ([Ca2+ ]i ) induces platelet aggregation, and influences the activation of aggregation associated-molecules. The increased [Ca2+ ]i activates both the Ca2+ /calmodulin-dependent phosphorylation of the myosin light chain and the diacylglycerol-dependent phosphorylation of pleckstrin to trigger granule secretion (i.e., dense body and α-granule) and platelet aggregation. This study was carried out to elucidate the antagonistic effect of 20(S)-ginsenoside Rg3 (G-Rg3) present in Panax ginseng Mayer on Ca2+ . G-Rg3 inhibited thrombin-induced human platelet aggregation in a dose-dependent manner and suppressed thrombin-induced elevation of [Ca2+ ]i mobilization. G-Rg3 increased the levels of cAMP, and subsequently, elevated the phosphorylation of inositol 1,4,5-triphosphate receptor I (Ser1756 ) during thrombin-induced human platelet aggregation. Moreover, G-Rg3 inhibited thapsigargin-induced Ca2+ influx and the thrombin-induced elevation of extracellular signal-regulated kinase 2 phosphorylation. G-Rg3 exhibited an inhibitory effect on [Ca2+ ]i levels leading to granule release and thus a therapeutic potential against platelet-mediated thrombotic disease is suggested.