An optimized herbal medicine containing Scutellaria baicalensis Georgi, Alisma orientale Juzepzuk, and Atractylodes japonica Koidzumi has potent antiplatelet and antithrombotic activities.

Background and aim: Platelet-derived thrombosis is important in the pathogenesis of cardiovascular diseases. HTB is an optimized herbal medicine including Scutellaria baicalensis Georgi, Alisma orientale Juzepzuk, and Atractylodes japonica Koidzumi. It is widely used in traditional medicine due to its anti-inflammatory and antioxidant effects. However, its antiplatelet and antithrombotic activities have not been completely validated. The current study aimed to examine the inhibitory effect of the novel herb formula HTB against platelet activation and thrombus formation. Experimental procedure: The antiplatelet activities of HTB via platelet aggregation, granule secretion, reactive oxygen species generation, and intracellular calcium mobilization were evaluated. Moreover, the antithrombotic effect of HTB via FeCl3-induced arterial thrombus formation in vivo in mice was assessed. The inhibitory effect of HTB against primary hemostasis was investigated based on transection tail bleeding time. Results and conclusion: HTB treatment significantly inhibited glycoprotein VI-mediated platelet aggregation, granule secretion, reactive oxygen species generation, and intracellular calcium mobilization. Biochemical studies revealed that HTB inhibited glycoprotein VI-mediated platelet signal transduction during cell activation. Further, its antioxidant effect might be derived by reducing the phosphorylation of the p47phox/Hic5 axis signalosome. Oral HTB treatment was effective in decreasing FeCl3-induced arterial thrombus formation without prolonging the tail bleeding time. HTB can be an effective therapeutic agent against thrombotic diseases.

Sinomenium acutum Modulates Platelet Aggregation and Thrombus Formation by Regulating the Glycoprotein VI-Mediated Signalosome in Mice.

Sinomenium acutum (SA) has long been used as a traditional medicine in China, Japan, and Korea to treat a wide range of diseases. It has been traditionally used to ameliorate inflammation and improve blood circulation. However, its role in platelet activation has not been thoroughly investigated. Hence, we conducted this study to assess the potential inhibitory effect of SA on platelet aggregation and thrombus formation. The antiplatelet activities of SA were evaluated by assessing platelet aggregation, granular secretion, intracellular Ca2+ mobilization, and the Glycoprotein (GP) VI-mediated signalosome. The thrombosis and bleeding time assays were used to investigate the effect of SA (orally administered at 50 and 100 mg/kg for seven days) in mice. SA treatment at concentrations of 50, 100, and 200 µg/mL significantly reduced GPVI-mediated platelet aggregation, granular secretion, and intracellular Ca2+ mobilization. Further biochemical studies revealed that SA inhibited spleen tyrosine kinase, phospholipase Cγ2, phosphatidylinositol 3-kinase, and AKT phosphorylation. Interestingly, oral administration of SA efficiently ameliorated FeCl3-induced arterial thrombus formation without prolonging the tail bleeding time. These findings suggest that SA has beneficial effects in thrombosis and hemostasis. Therefore, SA holds promise as an effective therapeutic agent for the treatment of thrombotic diseases.

Quercitrin inhibits platelet activation in arterial thrombosis.

BACKGROUND: The ingestion of flavonoids has been reported to be associated with reduced cardiovascular disease risk. Quercitrin is a common flavonoid in nature, and it exhibits antioxidant properties. Although the process of thrombogenesis is intimately related to cardiovascular disease risk, it is unclear whether quercitrin plays a role in thrombogenesis. PURPOSE: The aim of this study was to examine the antiplatelet effect of quercitrin in platelet activation. METHODS: Platelet aggregation, granule secretion, calcium mobilization, and integrin activation were used to assess the antiplatelet activity of quercitrin. Antithrombotic effect was determined in mouse using ferric chloride (FeCl3)-induced arterial thrombus formation in vivo and thrombus formation on collagen-coated surfaces under arteriolar shear in vitro. Transection tail bleeding time was used to evaluate whether quercitrin inhibited primary hemostasis. RESULTS: Quercitrin significantly impaired collagen-related peptide-induced platelet aggregation, granule secretion, reactive oxygen species generation, and intracellular calcium mobilization. Outside-in signaling of αIIbß3 integrin was significantly inhibited by quercitrin in a concentration-dependent manner. The inhibitory effect of quercitrin resulted from inhibition of the glycoprotein VI-mediated platelet signal transduction during cell activation. Further, the antioxidant effect is derived from decreased phosphorylation of components of the TNF receptor-associated factor 4/p47phox/Hic5 axis signalosome. Oral administration of quercitrin efficiently blocked FeCl3-induced arterial thrombus formation in vivo and thrombus formation on collagen-coated surfaces under arteriolar shear in vitro, without prolonging bleeding time. Studies using a mouse model of ischemia/reperfusion-induced stroke indicated that treatment with quercitrin reduced the infarct volume in stroke. CONCLUSIONS: Our results demonstrated that quercitrin could be an effective therapeutic agent for the treatment of thrombotic diseases.

Anti Xa oral anticoagulants inhibit in vivo platelet activation by modulating glycoprotein VI shedding.

Anti Xa non-vitamin K oral anticoagulants (anti Xa NOACs) seem to possess antiplatelet effect in vitro, but it is unclear if this occurs also in vivo. Aim of the study was to compare the effect on platelet activation of two anti Xa NOACs, namely apixaban and rivaroxaban, to warfarin, and to investigate the potential underlying mechanism by evaluating soluble glycoprotein GPVI (sGPVI), a protein involved in platelet activation. We performed a cross-sectional including AF patients treated with warfarin (n=30), or apixaban 10mg/day (n=40), or rivaroxaban 20mg/day (n=40). Patients were balanced for sex, age and cardiovascular risk factors. Platelet activation by urinary excretion of 11-dehydro-thromboxane (Tx) B2 and soluble GPVI (sGPVI) were analysed at baseline and after 3 months of treatment. Baseline TxB2 value was 155.2±42.7ng/mg creatinine. The 3 months-variation of urinary excretion of TxB2 was -6.5% with warfarin (p=0.197), -29% with apixaban (p<0.001) and -31% with rivaroxaban (p<0.001). Use of anti Xa NOACs was independently associated to the variation of urinary TxB2 (B: -0.469, p<0.001), after adjustment for clinical characteristics; sGPVI was significantly lower in patients treated with NOACs at 3 months (p<0.001), while only a trend for the warfarin group (p=0.116) was observed. The variation of sGPVI was correlated with that of TxB2 in the NOACs group (Rs: 0.527, p<0.001). In 15 patients (5 per each group) platelet recruitment was significantly lowered at 3 months by NOACs (p<0.001), but not by warfarin. The study provides evidence that anti Xa NOACs significantly inhibit urinary TxB2 excretion compared to warfarin, suggesting that NOACs possess antiplatelet property.