Abstract: Objective: To explore the inhibitory effect of the fibrinolytic enzyme from Lyophyllum ulmarium (LUFE) on rat thrombosis. Methods: SD rats were randomly divided into sham operation, model, positive control and low- and high-dose LUFE groups. All groups except the sham operation group were used to establish a ferric chloride (FeCl3)-induced carotid arterial thrombosis model. Before modeling, the rats in the positive control group and the low- and high-dose LUFE groups were administered with 10 mg/kg mb of aspirin and 100 and 400 mg/kg mb of LUFE, respectively, by gavage for 7 days. The changes in thrombus mass and carotid vascular histopathology were observed. The levels of tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), platelet-activating factor (PAF), soluble thrombomodulin (sTM), E-selectin and tissue factor (TF) were detected by enzyme-linked immunosorbent assay. The expression level of CD62P in platelets was detected by flow cytometry. In order to observe the effect of LUFE on platelet function, collagen-induced platelet activation was performed in vitro to observe the effect of LUFE on P-selectin, β-thromboglobulin (β-TG) and platelet membrane glycoprotein IIbIIIa (GPIIbIIIa) levels in platelet-rich plasma. Western blot was used to evaluate the effect of LUFE on the expression levels of phosphatidylinositol 3 kinase (PI3K), protein kinase B (Akt) and p38 mitogen-activated protein kinase (p38 MAPK) in platelets. Results: LUFE significantly reduced thrombus mass and vascular damage, inhibited the increase in serum sTM, E-selectin, TF, TNF-α, IL-6 and PAF levels in the thrombus model rats, and decreased the expression of platelet CD62P. LUFE could in vitro reduce the levels of P-selectin, β-TG and GPIIbIIIa in collagen induced platelet-rich plasma, and down-regulated the phosphorylation levels of platelet PI3K, Akt and p38 MAPK protein. Conclusion: LUFE has an anti-thrombotic effect, and its mechanism may be related to the protection of vascular endothelial cells and the inhibition of platelet activation.

Key words: Lyophyllum ulmarium; thrombolytic enzyme; antithrombotic effect; vascular endothelial cells; platelets