9-(tetrahydro-2-furyl)-adenine and Thrombosis

Chlorogenic acid is a potent phenolic antioxidant. However, its effect on platelet aggregation, a critical factor in arterial thrombosis, remains unclear. Consequently, chlorogenic acid-action mechanisms in preventing platelet activation and thrombus formation were examined.. Chlorogenic acid in a dose-dependent manner (0.1 to 1 mmol/L) inhibited platelet secretion and aggregation induced by ADP, collagen, arachidonic acid and TRAP-6, and diminished platelet firm adhesion/aggregation and platelet-leukocyte interactions under flow conditions. At these concentrations chlorogenic acid significantly decreased platelet inflammatory mediators (sP-selectin, sCD40L, CCL5 and IL-1β) and increased intraplatelet cAMP levels/PKA activation. Interestingly, SQ22536 (an adenylate cyclase inhibitor) and ZM241385 (a potent A2A receptor antagonist) attenuated the antiplatelet effect of chlorogenic acid. Chlorogenic acid is compatible to the active site of the adenosine A2A receptor as revealed through molecular modeling. In addition, chlorogenic acid had a significantly lower effect on mouse bleeding time when compared to the same dose of aspirin.. Antiplatelet and antithrombotic effects of chlorogenic acid are associated with the A2A receptor/adenylate cyclase/cAMP/PKA signaling pathway.

Topics: Adenine; Adenosine Triphosphate; Animals; Binding Sites; Bleeding Time; Cell Communication; Cell Line; Cell Survival; Chlorogenic Acid; Collagen; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Enzyme Activation; Hemorheology; Humans; Inflammation Mediators; Leukocytes; Mice; Models, Molecular; P-Selectin; Platelet Activation; Platelet Adhesiveness; Platelet Aggregation; Platelet Glycoprotein GPIIb-IIIa Complex; Receptor, Adenosine A2A; Thrombosis; Triazines; Triazoles

Amarogentin, an active principle of Gentiana lutea, possess antitumorigenic, antidiabetic, and antioxidative properties. Activation of platelets is associated with intravascular thrombosis and cardiovascular diseases. The present study examined the effects of amarogentin on platelet activation. Amarogentin treatment (15~60  μM) inhibited platelet aggregation induced by collagen, but not thrombin, arachidonic acid, and U46619. Amarogentin inhibited collagen-induced phosphorylation of phospholipase C (PLC) γ2, protein kinase C (PKC), and mitogen-activated protein kinases (MAPKs). It also inhibits in vivo thrombus formation in mice. In addition, neither the guanylate cyclase inhibitor ODQ nor the adenylate cyclase inhibitor SQ22536 affected the amarogentin-mediated inhibition of platelet aggregation, which suggests that amarogentin does not regulate the levels of cyclic AMP and cyclic GMP. In conclusion, amarogentin prevents platelet activation through the inhibition of PLC γ2-PKC cascade and MAPK pathway. Our findings suggest that amarogentin may offer therapeutic potential for preventing or treating thromboembolic disorders.

Topics: 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; Adenine; Adenosine Triphosphate; Animals; Arachidonic Acid; Collagen; Cyclic GMP; Guanylate Cyclase; Humans; Iridoids; MAP Kinase Signaling System; Mice; Oxadiazoles; Phospholipase C gamma; Plant Extracts; Platelet Activation; Protein Kinase C; Quinoxalines; Thrombin; Thromboembolism; Thrombosis