Rhizoma Bletillae polysaccharide elicits hemostatic effects in platelet-rich plasma by activating adenosine diphosphate receptor signaling pathway.

Rhizoma Bletillae, the tubes of Bletilla striata, has been traditionally used in China as a hemostatic agent. In preliminary studies, the major active fraction responsible for its hemostatic effect have been confirmed to be Rhizoma Bletillae polysaccharide (RBp), but the hemostatic mechanism of action of RBp is still unknown.The main aim of this study was to clarify its mechanism of hemostatic effect. RBp was prepared by 80 % ethanol precipitation of the water extract of Rhizoma Bletillae followed by the Sevag method to remove proteins. The average molecular weight (Mw) of the crude RBp maintained at a range of 30.06-200 KDa. The hemostatic effects of RBp were evaluated by testing its effect on the platelet aggregation of rat platelet-rich plasma (PRP). PRP was dealt with different concentrations of RBp and platelet aggregation was measured by the turbidimetric method. The hemostatic mechanism of RBp was investigated by examining its effect on platelet shape, platelet secretion, and activation of related receptors (P2Y1, P2Y12 and TXA2) by electron microscopy and the turbidimetric method. RBp significantly enhanced the platelet aggregations at concentrations of 50-200 mg/L in a concentration-dependent manner. The inhibitory rate of platelet aggregation was significantly increased by apyrase and Ro31-8220 in a concentration-dependent manner, while RBp-induced platelet aggregation was completely inhibited by P2Y1, P2Y12 and the PKC receptor antagonists. However, the aggregation was not sensitive to TXA2. RBp, the active ingredients of Rhizoma Bletillae responsible for its hemostatic effect, could significantly accelerate the platelet aggregation and shape change. The hemostatic mechanism may involve activation of the P2Y1, P2Y12, and PKC receptors in the adenosine diphosphate (ADP) receptor signaling pathway.

Tetramethylpyrazine attenuates atherosclerosis development and protects endothelial cells from ox-LDL.

PURPOSE: We assessed whether tetramethylpyrazine (TMP), an active ingredient of Ligusticum wallichii Franchat, attenuates atherosclerosis (AS) development in rabbits and protects endothelial cells injured by ox-LDL. METHODS: In vivo, rabbits subjected to atherosclerosis were treated with TMP (75 and 150 mg/kg) by oral gavage for 12 weeks. In vitro, rat aortic endothelial cells (RAECs) were stimulated by ox-LDL. RESULTS: TMP treatment with 75 and 150 mg/kg significantly reduced the relative atherosclerosis area ratio in the aorta (0.41 ± 0.042, 0.27 ± 0.047 vs. 0.66 ± 0.058 in AS), the ratio of intimal/medial thickness (0.54 ± 0.09, 0.39 ± 0.07 vs. 1.1 ± 0.3 in AS) and the number of monocytes in intimal (10.1 ± 2.8, 8.2 ± 2.0 vs. 14.1 ± 4.9 counts/mm(2) in AS). TMP also decreased levels of TC (15 ± 4.2 to 6.1 ± 1.2 mmol/L), TG (1.8 ± 0.3 to 1.08 ± 0.24 mmol/L), LDL-C (20.1 ± 4.3 to 10.2 ± 1.6 mmol/L) and increased HDL-C levels (0.40 ± 0.08 to 0.85 ± 0.17 mmol/L) in atherosclerosis rabbit plasma. TMP decreased the MCP-1 (187.3 ± 38.4 to 86.1 ± 17.2 pg/ml) and ICAM-1 (350.6 ± 43.7 to 260.6 ± 46.1 pg/ml) levels in plasma and inhibited LOX-1 expression in the rabbit aortas. Moreover, our in vitro study revealed that TMP suppressed monocyte adhesion to RAECs, inhibited RAEC migration, and down-regulated MCP-1 and ICAM-1 expression in ox-LDL-injured RAECs. Likewise, TMP inhibited LOX-1 and 5-LOX expression, and prevented nuclear accumulation of RelA/p65 and IκB degradation in ox-LDL-injured RAECs. Furthermore, TMP suppressed ox-LDL-induced activations of p-ERK, p-p38, and p-JNK MAPK. CONCLUSION: TMP produces a tangible protection in atherosclerosis and endothelial cells. TMP might be a potential protective agent for atherosclerosis.