Rutaecarpine, an Alkaloid from Evodia rutaecarpa, Can Prevent Platelet Activation in Humans and Reduce Microvascular Thrombosis in Mice: Crucial Role of the PI3K/Akt/GSK3ß Signal Axis through a Cyclic Nucleotides/VASP-Independent Mechanism.

The role of activated platelets in acute and chronic cardiovascular diseases (CVDs) is well established. Therefore, antiplatelet drugs significantly reduce the risk of severe CVDs. Evodia rutaecarpa (Wu-Chu-Yu) is a well-known Chinese medicine, and rutaecarpine (Rut) is a main bioactive component with substantial beneficial properties including vasodilation. To address a research gap, we investigated the inhibitory mechanisms of Rut in washed human platelets and experimental mice. At low concentrations (1-5 µM), Rut strongly inhibited collagen-induced platelet aggregation, whereas it exerted only a slight or no effect on platelets stimulated with other agonists (e.g., thrombin). Rut markedly inhibited P-selectin expression; adenosine triphosphate release; [Ca2+]i mobilization; hydroxyl radical formation; and phospholipase C (PLC)γ2/protein kinase C (PKC), mitogen-activated protein kinase, and phosphoinositide 3-kinase (PI3K)/Akt/glycogen synthase kinase-3ß (GSK3ß) phosphorylation stimulated by collagen. SQ22536 (an adenylate cyclase inhibitor) or ODQ (a guanylate cyclase inhibitor) did not reverse Rut-mediated antiplatelet aggregation. Rut was not directly responding to vasodilator-stimulated phosphoprotein phosphorylation. Rut significantly increased the occlusion time of fluorescence irradiated thrombotic platelet plug formation. The findings demonstrated that Rut exerts a strong effect against platelet activation through the PLCγ2/PKC and PI3K/Akt/GSK3ß pathways. Thus, Rut can be a potential therapeutic agent for thromboembolic disorders.

Anti-embolic effect of Taorenchengqi Tang in rats with embolic stroke induced by occluding middle cerebral artery.

OBJECTIVE: To investigate the anti-embolic effect of Taorenchengqi Tang (TRCQT), a formulas from Traditional Chinese Medicine, plus aspirin in rats with embolic stroke induced by selective occlusion of the middle cerebral artery (MCA). Possible side effects of hemorrhagic incident and other bleeding events and anti-platelet effect were also explored. METHODS: Ninety rats were randomly separated into 9 groups (n = 10): group 1 a sham-operated group (n = 10); groups 2 and 3 orally treated with an isovolumetric solvent (distilled water) for 1 and 3 months, followed by thromboembolic occlusion (n = 10); groups 4 and 5 orally treated with aspirin (5 mg/kg) alone for 1 and 3 months, followed by thromboembolic occlusion (n = 10); groups 6 and 7 orally treated with TRCQT (0.5 g/kg) alone for 1 and 3 months, followed by thromboembolic occlusion (n = 10); groups 8 and 9 orally treated with TRCQT plus aspirin for 1 and 3 months, respectively followed by thromboembolic occlusion (n = 10). The ischemic stroke in rats was induced by selective MCA occlusion. One was orally administered. After the treatments, rats' brains were removed, sectioned and stained with triphenyltetrazolium chloride (TTC) for infarct volume measurement. The incidence of subarachnoid hemorrhage (SAH) and intracerebral hemorrhage (ICH) were observed. A potential gastric bleeding side effect was assessed by measuring hemoglobin (Hb), and prothrombin time (PT). Collagen-induced platelet activation and tail vein bleeding time were measured. RESULTS: Treatment with TRCQT alone or in combination with aspirin reduced infarct volume for 1 (P < 0.05), and 3 (P < 0.01) months without SAH and ICH incidences, and gastric bleeding. TRCQT treatment for 1 month was also not altered PT. Moreover, a concentration dependent inhibition of collagen-induced platelet activation, followed by increasing of tail vein bleeding time was observed after TRCQT treatment. CONCLUSION: Either TRCQT alone or TRCQT plus aspirin exhibits potent neuroprotective effect by reducing infarct volume without changing the status of SAH, ICH and gastric bleeding possibly via inhibiting the platelet activation and increasing bleeding time.

Antrodia camphorata Potentiates Neuroprotection against Cerebral Ischemia in Rats via Downregulation of iNOS/HO-1/Bax and Activated Caspase-3 and Inhibition of Hydroxyl Radical Formation.

Antrodia camphorata (A. camphorata) is a fungus generally used in Chinese folk medicine for treatment of viral hepatitis and cancer. Our previous study found A. camphorata has neuroprotective properties and could reduce stroke injury in cerebral ischemia animal models. In this study, we sought to investigate the molecular mechanisms of neuroprotective effects of A. camphorata in middle cerebral artery occlusion (MCAO) rats. A selective occlusion of the middle cerebral artery (MCA) with whole blood clots was used to induce ischemic stroke in rats and they were orally treated with A. camphorata (0.25 and 0.75 g/kg/day) alone or combined with aspirin (5 mg/kg/day). To provide insight into the functions of A. camphorata mediated neuroprotection, the expression of Bax, inducible nitric oxide synthase (iNOS), haem oxygenase-1 (HO-1), and activated caspase-3 was determined by Western blot assay. Treatment of aspirin alone significantly reduced the expressions of HO-1 (P < 0.001), iNOS (P < 0.001), and Bax (P < 0.01) in ischemic regions. The reduction of these expressions was more potentiated when rats treated by aspirin combined with A. camphorata (0.75 g/kg/day). Combination treatment also reduced apoptosis as measured by a significant reduction in active caspase-3 expression in the ischemic brain compared to MCAO group (P < 0.01). Moreover, treatment of A. camphorata significantly (P < 0.05) reduced fenton reaction-induced hydroxyl radical (OH(•)) formation at a dose of 40 mg/mL. Taken together, A. camphorata has shown neuroprotective effects in embolic rats, and the molecular mechanisms may correlate with the downregulation of Bax, iNOS, HO-1, and activated caspase-3 and the inhibition of OH(•) signals.

Potential advantages of Chinese medicine Taohong Siwu Decoction () combined with tissue-plasminogen activator for alleviating middle cerebral artery occlusion-induced embolic stroke in rats.

OBJECTIVE: To investigate whether combination treatment with Taohong Siwu Decoction (, TSD) and recombinant tissue-type plasminogen activator (rt-PA) potentiate in reducing infarct volume and alleviate thromboembolic stroke in an in vivo rat model. METHOD: Adult male Wistar rats were subjected to embolic middle cerebral artery occlusion (MCAO) and treated with rt-PA (4 and 8 mg/kg) alone (n=5), TSD [0.7 g/(kg·day)] alone (n=5), combination of rt-PA and TSD, 24 h after stroke. Rats were sacrificed at 14 days after treatment and lesion volumes were measured. To investigate the underlying mechanism of neuroprotective effect of the combination treatment, cleaved caspase-3, tumor necrosis factor alpha (TNF-α), hypoxia-inducible factor (HIF)-1α, and inducible nitric oxide synthase (iNOS) immunostaining were performed. RESULTS: Combination treatment significantly reduced infarct volume of cerebral ischemic regions compared with treatment of rt-PA and TSD alone and that of the saline control group (P<0.01). A combined treatment of rt-PA (4 mg/kg) with TSD [0.7 g/(kg·day)] significantly increased cerebral blood flow in a time (100 and 120 min) dependent manner (P<0.05). Interestingly, despite treatment of rt-PA (4 mg/kg) alone significantly reduced the expressions of HIF-1α, TNF-α, and iNOS in ischemic regions, reduction of these expressions were more potentiated when combined with TSD (P<0.05). Combination treatment also reduced apoptosis as measured by a significant reduction in active caspase-3 expression in the ischemic brain compared with the MCAO group (P<0.01). CONCLUSIONS: A combination of low-dose rt-PA and TSD after embolic stroke reduced infarct volume, improved cerebral blood flow and provided neuroprotection and these effects were associated with reduction of apoptosis and attenuation of HIF-1α, TNF-α and iNOS expression. These results provide a positive contribution to better understand the therapeutic value of the combination of TSD with rt-PA in ischemic stroke and may support further clinical evaluation.

Novel bioactivity of ellagic Acid in inhibiting human platelet activation.

Pomegranates are widely consumed either as fresh fruit or in beverage form as juice and wine. Ellagic acid possesses potent antioxidative properties; it is known to be an effective phytotherapeutic agent with antimutagenic and anticarcinogenic qualities. Ellagic acid (20 to 80 µ M) exhibited a potent activity in inhibiting platelet aggregation stimulated by collagen; however, it did not inhibit platelet aggregation stimulated by thrombin, arachidonic acid, or U46619. Treatment with ellagic acid (50 and 80 µ M) significantly inhibited platelet activation stimulated by collagen; this alteration was accompanied by the inhibition of relative [Ca(2+)] i mobilization, and the phosphorylation of phospholipase C (PLC) γ 2, protein kinase C (PKC), mitogen-activated protein kinases (MAPKs), and Akt, as well as hydroxyl radical (OH(●)) formation. In addition, ellagic acid also inhibited p38 MAPK and Akt phosphorylation stimulated by hydrogen peroxide. By contrast, ellagic acid did not significantly affect PKC activation and platelet aggregation stimulated by PDBu. This study is the first to show that, in addition to being considered a possible agent for preventing tumor growth, ellagic acid possesses potent antiplatelet properties. It appears to initially inhibit the PLCγ2-PKC cascade and/or hydroxyl radical formation, followed by decreased phosphorylation of MAPKs and Akt, ultimately inhibiting platelet aggregation.