Platelet P2Y₁₂ receptors are involved in the haemostatic effect of notoginsenoside Ft1, a saponin isolated from Panax notoginseng

Abstract

BACKGROUND AND PURPOSESaponins isolated from Panax notoginseng (Burk.) F.H. Chen have been shown to relieve thrombogenesis and facilitate haemostasis. However, it is not known which saponin accounts for this haemostatic effect. Hence, in the present study we aimed to identify which saponins contribute to its haemostatic activity and to elucidate the possible underlying mechanisms. EXPERIMENTAL APPROACHPlatelet aggregation was analysed using a platelet aggregometer. Prothrombin time, activated partial thromboplastin time and thrombin time were measured using a blood coagulation analyser, which was further corroborated with bleeding time and thrombotic assays. The interaction of notoginsenoside Ft1 with the platelet P2Y12 receptor was determined by molecular docking analysis, cytosolic Ca 2+ and cAMP measurements, and phosphorylation of PI3K and Akt assays. KEY RESULTSAmong the saponins examined, Ft1 was the most potent procoagulant and induced dose-dependent platelet aggregation. Ft1 reduced plasma coagulation indexes, decreased tail bleeding time and increased thrombogenesis. Moreover, it potentiated ADP-induced platelet aggregation and increased cytosolic Ca 2+ accumulation, effects that were attenuated by clopidogrel. Molecular docking analysis suggested that Ft1 binds to platelet P2Y12 receptors. The increase in intracellular Ca 2+ evoked by Ft1 in HEK293 cells overexpressing P2Y12 receptors could be blocked by ticagrelor. Ft1 also affected the production of cAMP and increased phosphorylation of PI3K and Akt downstream of P2Y12 signalling pathways. CONCLUSION AND IMPLICATIONSFt1 enhanced platelet aggregation by activating a signalling network mediated through P2Y12 receptors. These novel findings may contribute to the effective utilization of this compound in the therapy of haematological disorders.

Panax notoginseng: A Double-Edged Sword in Haemostasis?

“…Gao et al [9] showed that different NTS may either increase or decrease platelet aggregation in the same experimental setting [9], further supporting the apparently contradicting results obtained by others. The source of the herbs aside, however, discrepancy in findings may also arise from different preparation methods (e.g.…”

“…Parameters of coagulation, such as prothrombin time, activated partial thromboplastin time and thrombin time, were also lengthened after Ft1 treatment [9]. This study [9] did not examine the haemostatic effect of raw notoginseng (water or alcohol extract) or dencichine, which will be of value to compare the efficacy of the various samples in the same experimental setting. Nevertheless, the enhanced platelet activity of NTS (notably Ft1) has been demonstrated.…”

“…In contrary, the water extract of notoginseng has only weak haemostatic effect [7] and may be attributed to dencichine, which is water-soluble [6]. Further analysis of the haemostatic effect of individual NTS showed that the notoginsenoside Ft1 was among the strongest pro-haemostatic saponin in notoginseng [9]. Similar to dencichine, Ft1 also exerted its action on platelets, activating the ADP (P2Y 12 ) receptor to initiate platelet aggregation [9].…”

“…Further analysis of the haemostatic effect of individual NTS showed that the notoginsenoside Ft1 was among the strongest pro-haemostatic saponin in notoginseng [9]. Similar to dencichine, Ft1 also exerted its action on platelets, activating the ADP (P2Y 12 ) receptor to initiate platelet aggregation [9]. Parameters of coagulation, such as prothrombin time, activated partial thromboplastin time and thrombin time, were also lengthened after Ft1 treatment [9].…”

“…Similar to dencichine, Ft1 also exerted its action on platelets, activating the ADP (P2Y 12 ) receptor to initiate platelet aggregation [9]. Parameters of coagulation, such as prothrombin time, activated partial thromboplastin time and thrombin time, were also lengthened after Ft1 treatment [9]. This study [9] did not examine the haemostatic effect of raw notoginseng (water or alcohol extract) or dencichine, which will be of value to compare the efficacy of the various samples in the same experimental setting.…”