The Characteristic Of Steroidal Saponins On Platelet Aggregation Through Structure-activity Assay And Mechanism Study

The rhizome of Paris polyphylla Sm. var. yunnanensis is widely used in traditional Chinese medicine for treatment of bleeding. In this study, the results showed that total steroid saponins extracted from Paris polyphylla (TSSP) could promote hemostasis in vivo and dose-dependently induce rat PRP aggregation in vitro. The platelet aggregation induced by steroidal saponins is inhibited by cyclic AMP, enhanced by G_z activation and mediated by protein kinase phosphorylation. Through bioassay-guided separation, we got total furostanol saponin with no activity and total spirostanol saponin with platelet aggregation activity, Through structure-activity relationship study, we found the structure of sapogenin skeleton and the conformation of the 3-O-sugar moiety are essential for steroidal saponins in inducing platelet aggregation. Further evidence revealed thatα_2bβ₃ activation is the prerequisite for pennogenin glycosides inducing platelet aggregation and the synergistic actions on platelet aggregation exist between pennogenin glycosides and the known platelet agonists, proposing these saponins have the characteristic of platelet agonists. Although, the diosgenin glycosides showed platelet aggregation activity, the characteristic and the underlying molecular mechanism are of great difference with pennogenin glycosides. The synergistic and antagonist effect exist among steroid saponins with different structure. Together, we firstly identified pennogenin glycosides with spirostanol structure are active ingredients of Paris polyphylla in promoting hemostasis in vivo, and the mode of their action on platelets indicated they are representing a new type of platelet agonists.