thromboxane-a2 and cordycepin

In this study, we investigated the effect of cordycepin-enriched (CE)-WIB801C from Cordyceps militaris on ADP (20 µM)-stimulated platelet aggregation. CE-WIB801C dose-dependently inhibited ADP-induced platelet aggregation, and its IC50 value was 18.5 μg/mL. CE-WIB801C decreased TXA2 production, but did not inhibit the activities of COX-1 and thromboxane synthase (TXAS) in ADP-activated platelets, which suggests that the inhibition of TXA2 production by CE-WIB801C is not resulted from the direct inhibition of COX-1 and TXAS. CE-WIB801C inhibited ATP release and [Ca(2+)]i mobilization, and increased cAMP level and IP3RI (Ser(1756)) phosphorylation in ADP-activated platelets. cAMP-dependent protein kinase (A-kinase) inhibitor Rp-8-Br-cAMPS increased CE-WIB801C-inhibited [Ca(2+)]i mobilization, and strongly inhibited CE-WIB801C-increased IP3RI (Ser(1756)) phosphorylation. CE-WIB801C elevated the phosphorylation of VASP (Ser(157)), an A-kinase substrate, but inhibited fibrinogen binding to αIIb/β3. These results suggest that CE-WIB801C-elevated cAMP involved in IP3RI (Ser(1756)) phosphorylation to inhibit [Ca(2+)]i mobilization and, VASP (Ser(157)) phosphorylation to inhibit αIIb/β3 activation. Therefore, in this study, we demonstrate that CE-WIB801C may have a preventive or therapeutic potential for platelet aggregation-mediated diseases, such as thrombosis, myocardial infarction, atherosclerosis, and ischemic cerebrovascular disease.

Topics: 8-Bromo Cyclic Adenosine Monophosphate; Adenosine Diphosphate; Adenosine Triphosphate; Blood Platelets; Calcium; Calcium Signaling; Cell Adhesion Molecules; Cordyceps; Cyclic AMP; Cyclooxygenase 1; Deoxyadenosines; Dose-Response Relationship, Drug; Fibrinogen; Herb-Drug Interactions; Humans; Inositol 1,4,5-Trisphosphate Receptors; Microfilament Proteins; Phosphoproteins; Phosphorylation; Plant Extracts; Platelet Aggregation; Platelet Aggregation Inhibitors; Thionucleotides; Thromboxane A2; Thromboxane-A Synthase

Cordycepin (3'-deoxyadenosine) is isolated from Cordyceps militaris, a species of the fungal genus Cordyceps. Cordycepin is an ingredient used in traditional Chinese medicine and is prescribed for various diseases, such as cancer and chronic inflammation. In this study, we investigated the novel effect of cordycepin (3'-deoxyadenosine) on collagen-induced human platelet aggregation. Cordycepin inhibited dose-dependently collagen-induced platelet aggregation in the presence of various concentrations of exogenous CaCl(2). Of two aggregation-inducing molecules, cytosolic free Ca(2+) ([Ca(2+)](i)) and thromboxane A(2) (TXA(2)), cordycepin (500 microM) blocked the up-regulation of [Ca(2+)](i), by up to 74%, but suppressed TXA(2) production by 46%. Subsequently, Ca(2+)-dependent phosphorylation of both 47-kDa and 20-kDa proteins in collagen-treated platelets was potently diminished by cordycepin. However, upstream pathways for producing these two inducers, such as the activation of phospholipase C-gamma2 (PLC-gamma2) (assessed by the phosphotyrosine level) and the formation of inositol 1,4,5-trisphosphate (IP(3)), were not altered by cordycepin. Cordycepin increased the level of second messengers adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP) in collagen-stimulated platelets. Whereas the NO-sensitive guanylyl cyclase inhibitor ODQ did not alter the cordycepin-induced up-regulation of cGMP, the adenylyl cyclase inhibitor SQ22536 completely blocked the cAMP enhancement mediated by cordycepin, indicating that cordycepin had different modes of action. Therefore, our data suggest that the inhibitory effect of cordycepin on platelet aggregation might be associated with the down-regulation of [Ca(2+)](i) and the elevation of cAMP/cGMP production.

Topics: Calcium; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cyclic GMP; Deoxyadenosines; Dose-Response Relationship, Drug; Humans; Phospholipase C gamma; Phosphorylation; Platelet Aggregation; Platelet Aggregation Inhibitors; Thromboxane A2

Cordycepin (3'-deoxyadenosine), which comes from Cordyceps militaris, the Chinese medicinal fungal genus Cordyceps, is known to have anti-tumour activity. In this study, we investigated the novel effect of cordycepin on human platelet aggregation that was induced by U46619, a thromboxane A(2) (TXA(2)) analogue. TXA(2) is an aggregation-inducing autacoidal molecule that is produced in various agonist-activated platelets. Cordycepin completely inhibited U46619-induced platelet aggregation and simultaneously reduced cytosolic free Ca(2+) ([Ca(2+)](i)), which was increased by U46619 (5 microM) up to 66%. Furthermore, the U46619-stimulated phosphorylation of Ca(2+)-dependent proteins (20 kDa of a myosin light chain and 47 kDa of pleckstrin) was strongly inhibited by cordycepin. These results suggest that cordycepin may have a beneficial effect on autacoidal TXA(2)-mediated thrombotic diseases by inhibiting TXA(2)-induced platelet aggregation via suppression of the Ca(2+) level.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Antineoplastic Agents; Blood Proteins; Calcium; Calcium Chloride; Calcium Signaling; Deoxyadenosines; Dose-Response Relationship, Drug; Humans; Medicine, Chinese Traditional; Molecular Structure; Myosin Light Chains; Phosphoproteins; Phosphorus Radioisotopes; Phosphorylation; Platelet Aggregation; Platelet Aggregation Inhibitors; Thromboxane A2