Morin hydrate inhibits platelet activation and clot retraction by regulating integrin αIIbβ3, TXA2, and cAMP levels.Eur J Pharmacol 2019; 865:172734EJ
Morin hydrate is an active constituent of Morus alba L, Prunus dulcis, and Cudrania tricuspidata and has been reported to inhibit platelet activation in vivo and in vitro, but no reports have been issued on its regulation of αIIbβ3, a platelet-specific integrin and thromboxane A2 (TXA2), positive feedback molecule. In this study, we investigated the anti-platelet activity of morin hydrate in collagen- and thrombin-induced human platelets and attempted to identify the mechanism responsible for integrin αIIbβ3 activation and TXA2 generation. Our results demonstrated that morin hydrate (25-100 μM) inhibited collagen- and thrombin-induced platelet aggregation, granule secretion (P-selectin expression, ATP, and serotonin release), calcium mobilization, TXA2 production, integrin αIIbβ3 activation, and clot retraction. Additionally, morin hydrate attenuated the phosphorylations of phospholipase Cγ2 (PLCγ2), cytosolic phospholipase A2 (cPLA2), phosphoinositide 3-kinase (PI3K), Akt, c-Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK), and enhanced the phosphorylations of inositol trisphosphate receptor (IP3 receptor) and cyclic adenosine monophosphate (cAMP) generation. However, it had no effect on the coagulation pathway. Taken together, these observations indicate morin hydrate inhibits platelet-mediated thrombosis by down-regulating TXA2 production and integrin αIIbβ3 activation, and by upregulating cAMP generation, and thus, inhibits clot retraction. These results suggest morin hydrate may have therapeutic potential as a treatment for platelet-activation-related diseases.