Inhibitory effects of total saponin from Korean Red Ginseng on [Ca(2+)]i mobilization through phosphorylation of cyclic adenosine monophosphate-dependent protein kinase catalytic subunit and inositol 1,4,5-trisphosphate receptor type I in human platelets

The effects of ginsenosides on platelet aggregation and vascular intima in the treatment of cardiovascular diseases: From molecular mechanisms to clinical applications

Thrombosis initiated by abnormal platelet aggregation is a pivotal pathological event that precedes most cases of cardiovascular diseases (CVD). Recently, growing evidence indicates that platelet could be a potential target for CVD prevention. However, as the conventional antithrombotic management strategy, applications of current antiplatelet agents are somewhat limited by their various side effects, such as bleeding risk and drug resistance. Hence, efforts have been made to search for agents as complementary therapies. Ginsenoside, the principal active component extracted from Panax ginseng, has gained much attention for its regulations on multiple crucial events of platelet aggregation. From structural characteristics to clinical applications, this review anatomized the intrinsic structure-function relationship of antiplatelet potency of ginsenosides, and the involved signal pathways were specifically summarized. Additionally, the emphasis was placed on clinical studies that investigate the antithrombotic efficacy of ginsenosides in the treatment of CVD. Further, a broad overview of approaches for improving the bioavailability of ginsenosides was concluded. Limitations and prospects of current studies were also discussed. This study may provide some new insights into the systematic understanding of ginsenosides in CVD treatment and lay a foundation for future research.

Anti-platelet role of Korean ginseng and ginsenosides in cardiovascular diseases

Cardiovascular diseases prevail among modern societies and underdeveloped countries, and a high mortality rate has also been reported by the World Health Organization affecting millions of people worldwide. Hyperactive platelets are the major culprits in thrombotic disorders. A group of drugs is available to deal with such platelet-related disorders; however, sometimes, side effects and complications caused by these drugs outweigh their benefits. Ginseng and its nutraceuticals have been reported to reduce the impact of thrombotic conditions and improve cardiovascular health by antiplatelet mechanisms. This review provides (1) a comprehensive insight into the available pharmacological options from ginseng and ginsenosides (saponin and nonsaponin fractions) for platelet-originated cardiovascular disorders; (2) a discussion on the impact of specific functional groups on the modulation of platelet functions and how structural modifications among ginsenosides affect platelet activation, which may further provide a basis for drug design, optimization, and the development of ginsenoside scaffolds as pharmacological antiplatelet agents; (3) an insight into the synergistic effects of ginsenosides on platelet functions; and (4) a perspective on future research and the development of ginseng and ginsenosides as super nutraceuticals.

In vitro and in silico evaluation of stereoselective effect of ginsenoside isomers on platelet P2Y12 receptor

BACKGROUND

P2Y₁₂ receptor (P2Y₁₂R) is a newly discovered Gi-coupled ADP receptor that plays critical role in platelet function. Ginsenosides are the main constituents responsible for most of pharmacological actions of ginseng, especially cardio-cerebrovascular protective efficacy that is closely related to the influence on platelet function.

HYPOTHESIS/PURPOSE

To explore stereoselective effect of naturally abundant ginsenoside isomers, including the C-20 epimers of protopanaxadiol (PPD), protopanaxatriol (PPT), and their glycosides Rg2, Rg3, Rh1, Rh2 on P2Y₁₂R in platelets.

STUDY DESIGN/METHODS

Both in vitro assay and in silico molecular docking study were performed to investigate the stereoselective effects.

RESULTS

In vitro assay using washed rat platelets revealed differential effects of ginsenoside isomers on ADP-induced platelet aggregation with the direction and degree of action varying with chemical structures. More to the point, the ginsenoside 20S-Rh2 but not its 20R-epimer was found to be the only one that could significantly promote in vitro platelets aggregation induced by ADP. The correlation analysis demonstrated that ginsenosides may have impact on P2Y₁₂R related platelet functions through a cAMP-dependent pathway. Molecular docking stimulation further indicated that ginsenoside isomers could be potent substrate of P2Y₁₂R with differential protein-ligand interaction that would be responsible for the stereoselective efficacy of C-20 ginsenoside epimers. Hydrogen bonding with Asp266 via the C-20 hydroxyl may provide ginsenosides with promoting effect on ADP-induced platelets aggregation, whereas interactions with Tyr105 could contribute to the promotion of inhibitory efficacy.

CONCLUSION

Ginsenosides are potent P2Y₁₂R substrate with stereoselective effects on P2Y₁₂R-related platelet function, which result from their chemical diversity and are closely related to the different interaction ways as P2Y₁₂R ligand.

Inhibitory effects of thromboxane A2 generation by ginsenoside Ro due to attenuation of cytosolic phospholipase A2 phosphorylation and arachidonic acid release

BACKGROUND

Thromboxane A2 (TXA2) induces platelet aggregation and promotes thrombus formation. Although ginsenoside Ro (G-Ro) from Panax ginseng is known to exhibit a Ca2+-antagonistic antiplatelet effect, whether it inhibits Ca2+-dependent cytosolic phospholipase A2 (cPLA2α) activity to prevent the release of arachidonic acid (AA), a TXA2 precursor, is unknown. In this study, we attempted to identify the mechanism underlying G-Ro-mediated TXA2 inhibition.

METHODS

We investigated whether G-Ro attenuates TXA2 production and its associated molecules, such as cyclooxygenase-1 (COX-1), TXA2 synthase (TXAS), cPLA2α, mitogen-activated protein kinases, and AA. To assay COX-1 and TXAS, we used microsomal fraction of platelets.

RESULTS

G-Ro reduced TXA2 production by inhibiting AA release. It acted by decreasing the phosphorylation of cPLA2α, p38-mitogen-activated protein kinase, and c-Jun N-terminal kinase1, rather than by inhibiting COX-1 and TXAS in thrombin-activated human platelets.

CONCLUSION

G-Ro inhibits AA release to attenuate TXA2 production, which may counteract TXA2-associated thrombosis.

Inhibitory Effects of Ginsenoside Ro on Clot Retraction through Suppressing PI3K/Akt Signaling Pathway in Human Platelets

Glycoprotein IIb/IIIa (αIIb/β₃) is the most abundant integrin on platelet surfaces, which is involved in interaction between platelets, and triggers an intracellular signaling cascade, platelet shape changes, granule secretion, and clot retraction. In this study, we evaluated the effect of ginsenoside Ro (G-Ro) on the binding of fibronectin and fibrinogen to αIIb/β₃ and clot retraction. We found that G-Ro inhibited thrombin-induced platelet aggregation dose-dependently and attenuated the fibronectin-, and fibrinogen-binding to αIIb/β₃ through the dephosphorylation of phosphoinositide 3-kinase p85 and Akt, which influence clot retraction, reflecting the intensification of thrombus. We observed that G-Ro is involved in αIIb/β₃ in human platelets. These results suggest that G-Ro is beneficial, inhibiting fibronectin adhesion, fibrinogen binding, and clot retraction. Therefore, G-Ro in Panax ginseng may prevent platelet aggregation-mediated thrombotic disease.

Inhibitory Effect of 20(S)-Ginsenoside Rg3 on Human Platelet Aggregation and Intracellular Ca2+ 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.

Vasodilator-stimulated phosphoprotein-phosphorylation by ginsenoside Ro inhibits fibrinogen binding to αIIb/β3 in thrombin-induced human platelets

BACKGROUND

Glycoprotein IIb/IIIa (αIIb/β3) is involved in platelet adhesion, and triggers a series of intracellular signaling cascades, leading to platelet shape change, granule secretion, and clot retraction. In this study, we evaluated the effect of ginsenoside Ro (G-Ro) on the binding of fibrinogen to αIIb/β3.

METHODS

We investigated the effect of G-Ro on regulation of signaling molecules affecting the binding of fibrinogen to αIIb/β3, and its final reaction, clot retraction.

RESULTS

We found that G-Ro dose-dependently inhibited thrombin-induced platelet aggregation and attenuated the binding of fibrinogen to αIIb/β3 by phosphorylating cyclic adenosine monophosphate (cAMP)-dependently vasodilator-stimulated phosphoprotein (VASP; Ser157). In addition, G-Ro strongly abrogated the clot retraction reflecting the intensification of thrombus.

CONCLUSION

We demonstrate that G-Ro is a beneficial novel compound inhibiting αIIb/β3-mediated fibrinogen binding, and may prevent platelet aggregation-mediated thrombotic disease.

Total saponin from Korean Red Ginseng inhibits binding of adhesive proteins to glycoprotein IIb/IIIa via phosphorylation of VASP (Ser(157)) and dephosphorylation of PI3K and Akt

Background

Binding of adhesive proteins (i.e., fibrinogen, fibronectin, vitronectin) to platelet integrin glycoprotein IIb/IIIa (αIIb/β₃) by various agonists (thrombin, collagen, adenosine diphosphate) involve in strength of thrombus. This study was carried out to evaluate the antiplatelet effect of total saponin from Korean Red Ginseng (KRG-TS) by investigating whether KRG-TS inhibits thrombin-induced binding of fibrinogen and fibronectin to αIIb/β₃.

Methods

We investigated the effect of KRG-TS on phosphorylation of vasodilator-stimulated phosphoprotein (VASP) and dephosphorylation of phosphatidylinositol 3-kinase (PI3K) and Akt, affecting binding of fibrinogen and fibronectin to αIIb/β₃, and clot retraction.

Results

KRG-TS had an antiplatelet effect by inhibiting the binding of fibrinogen and fibronectin to αIIb/β₃ via phosphorylation of VASP (Ser¹⁵⁷), and dephosphorylation of PI3K and Akt on thrombin-induced platelet aggregation. Moreover, A-kinase inhibitor Rp-8-Br-cyclic adenosine monophosphates (cAMPs) reduced KRG-TS-increased VASP (Ser¹⁵⁷) phosphorylation, and increased KRG-TS-inhibited fibrinogen-, and fibronectin-binding to αIIb/β₃. These findings indicate that KRG-TS interferes with the binding of fibrinogen and fibronectin to αIIb/β₃ via cAMP-dependent phosphorylation of VASP (Ser¹⁵⁷). In addition, KRG-TS decreased the rate of clot retraction, reflecting inhibition of αIIb/β₃ activation. In this study, we clarified ginsenoside Ro (G-Ro) in KRG-TS inhibited thrombin-induced platelet aggregation via both inhibition of [Ca²⁺]_i mobilization and increase of cAMP production.

Conclusion

These results strongly indicate that KRG-TS is a beneficial herbal substance inhibiting fibrinogen-, and fibronectin-binding to αIIb/β₃, and clot retraction, and may prevent platelet αIIb/β₃-mediated thrombotic disease. In addition, we demonstrate that G-Ro is a novel compound with antiplatelet characteristics of KRG-TS.