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Background and Purpose: Thrombosis is a major cause of morbidity and mortality worldwide. Platelet activation by exposed collagen through glycoprotein VI (GPVI) and formation of neutrophil extracellular traps (NETs) are critical pathogenic factors for arterial and venous thrombosis. Both events are regulated by spleen tyrosine kinase (Syk)‐mediated signalling events. Asebogenin is a dihydrochalcone whose pharmacological effects remain largely unknown. This study aims to investigate the antithrombotic effects of asebogenin and the underlying molecular mechanisms. Experimental Approach: Platelet aggregation was assessed using an aggregometer. Platelet P‐selectin exposure, integrin activation and calcium mobilization were determined by flow cytometry. NETs formation was assessed by SYTOX Green staining and immunohistochemistry. Quantitative phosphoproteomics, microscale thermophoresis, in vitro kinase assay and molecular docking combined with dynamics simulation were performed to characterize the targets of asebogenin. The in vivo effects of asebogenin on arterial thrombosis were investigated using FeCl3‐induced and laser‐induced injury models, whereas those of venous thrombosis were induced by stenosis of the inferior vena cava. Key Results: Asebogenin inhibited a series of GPVI‐induced platelet responses and suppressed NETs formation induced by proinflammatory stimuli. Mechanistically, asebogenin directly interfered with the phosphorylation of Syk at Tyr525/526, which is important for its activation. Further, asebogenin suppressed arterial thrombosis demonstrated by decreased platelet accumulation and fibrin generation and attenuated venous thrombosis determined by reduced neutrophil accumulation and NETs formation, without increasing bleeding risk. Conclusion and Implications: Asebogenin exhibits potent antithrombotic effects by targeting Syk and is a potential lead compound for the development of efficient and safe antithrombotic agents. [ABSTRACT FROM AUTHOR]

Background and Purpose: Considerable evidence indicates that the beta(2)-adrenoceptor agonist clenbuterol decreases apoptosis in a rodent model of ischaemic cardiomyopathy. In this study, we investigated the effects of clenbuterol on infarct size caused by myocardial ischaemia/reperfusion (I/R) in anaesthetized rats.Experimental Approach: Rats were randomly assigned to the following groups: (i) sham (ii) I/R (iii) clenbuterol + I/R (iv) ICI 118551 + clenbuterol + I/R (v) metoprolol + clenbuterol + I/R (vi) metoprolol + I/R (vii) pertussis toxin + clenbuterol + I/R. Under anaesthesia, left anterior descending coronary artery was occluded for 30 min followed by reperfusion for 2 h.Key Results: Compared with the control I/R group,the clenbuterol (0.5 mg.kg(-1), i.p.) group had reduced infarct size, improved diastolic function and sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase (SERCA) activity, increased superoxide dismutase activity, and decreased malondialdehyde (MDA) level and LDH, CK release. Clenbuterol increased the phosphorylation of ERK1/2, which resulted in inhibition of myocardial apoptosis as indicated by the reduction of terminal deoxynucleotidyltransferase end labelling-positive staining, Bax/Bcl-2 mRNA and caspase-3 protein expression. The G(i)-protein inhibitor pertussis toxin blocked the clenbuterol-induced improvement in cardiac function and infarct size. Pretreatment with ICI 118551(a selective beta(2)-adrenoceptor antagonist) inhibited the effects of clenbuterol mentioned above. The beta(1)-adrenoceptor agonist metoprolol had similar effects to clenbuterol but failed to reduce MDA and improve SERCA activity. When administered together, metoprolol and clenbuterol did not induce synergistic effects.Conclusions and Implications: Clenbuterol pretreatment provides significant cardioprotection against ischaemia/reperfusion injury and this is mediated by the beta(2)-adrenoceptor-G(i)-protein signalling. A combination of the beta(2)-adrenoceptor agonist clenbuterol and the beta(1)-antagonist metoprolol did not lead to a synergistic anti-apoptotic effect. [ABSTRACT FROM AUTHOR]