The Study Of Pentamethylquercetin On Antiplatelet And Antithrombotic Effect

Part ? The effects of pentamethylquercetin on human platelet function and its mechanismObjectiveTo study the effects of pentamethylquercetin on human platelet function and its mechanism.MethodsThe toxicity of pentamethylquercetin on human washed platelets was detected by LDH Assay kit. The effects of pentamethylquercetin on different agonist (ADP, collagen, thrombin, U46619, epinephrine and PDBu)-induced platelet aggregation and different agonist (collagen and thrombin) induced ADP secretion were examined with an aggregometer. The effects of pentamethylquercetin on different agonist (collagen and thrombin)-induced P-selectin expression were examined by flow cytometric. The effects of pentamethylquercetin on platelet adhesion to collagen was observed with immunofluorescence.. Western blot was used to detect the effects of pentamethylquercetin on the major protein of platelet signaling pathway. The effects of pentamethylquercetin on platelet spreading on immobilized fibrinogen were observed with immunofluorescence. The effects of pentamethylquercetin on clot retraction were also investigated. Western blot was used to detect the effects of pentamethylquercetin on platelet outside-in signal transduction.ResultsPentamethylquercetin had no toxicity effect on platelet. Pentamethylquercetin inhibited human PRP aggregation by ADP and collagen and extended the time to human PRP aggregation maximum by epinephrine in low dose, but not in high dose. Pentamethylquercetin inhibited collagen, thrombin, U46619 and PDBu induced human washed platelet aggregation. Pentamethylquercetin also inhibited collagen and thrombin induced granule secretion. The number of adherent platelets on collagen was markedly reduced by pretreatment with pentamethylquercetin. Pentamethylquercetin inhibited the phosphorylation of PI3K-Akt-GSK3?, MAPK-ERK1/2 and Syk-PLCy2 signaling pathway. Pentamethylquercetin inhibited platelet spreading area on immobilized fibrinogen, clot retraction, and platelet outside-in signaling.ConclusionsPentamethylquercetin may possess antiplatelet activity by inhibiting platelet aggregation, release, adhesion and spreading. The underlying mechanism is related to its inhibiting the PI3K-Akt-GSK3?, MAPK-ERK1/2, Syk-PLCy2 pathway, namely platelet "inside-out" and "outside-in" signaling pathway.Part ? The effects of pentamethylquercetin on thrombosis in vivoObjectiveTo study the effects of pentamethylquercetin on thrombosis in vivo.MethodsThe effects of pentamethylquercetin on platelet aggregation in rat in vivo were detected by aggregometer. The effects of pentamethylquercetin on mice survival rates and the corresponding pathological changes in lung tissue were investigated by collagen-epinephrine-induced acute pulmonary thrombus formation mouse model. The effects of pentamethylquercetin on ferric chloride-induced arterial thrombosis in vivo were also examined. The effects of pentamethylquercetin on physiological hemostasis were tested by using the mouse tail bleeding model.ResultsPentamethylquercetin inhibited collagen and thrombin-induced platelet aggregation in vivo. Pentamethylquercetin significantly attenuated thrombus formation and mortality by collagen-epinephrine induced acute pulmonary thrombus mouse model. Pentamethylquercetin had a protect effect on ferric chloride-induced carotid arterial thrombosis in vivo. Pentamethylquercetin had no effect on physiological hemostasis.ConclusionPentamethylquercetin inhibits thrombosis in vivo.