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

BACKGROUND

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

METHODS

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

RESULTS

G-Ro reduced TXA production by inhibiting AA release. It acted by decreasing the phosphorylation of cPLA, 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 TXA production, which may counteract TXA-associated thrombosis.