Abstract
Bleeding is the most common and serious adverse effect of currently available antiplatelet drugs. Many efforts are being made to develop novel antithrombotic agents without bleeding risks. Shear stress-induced platelet aggregation (SIPA), which occurs under abnormally high shear stress, plays a crucial role in the development of arterial thrombotic diseases. Here, we demonstrate that protocatechuic acid (PCA), a bioactive phytochemical from Lonicera (honeysuckle) flowers, selectively and potently inhibits high shear (>10,000 s−1)-induced platelet aggregation. In isolated human platelets, PCA decreased SIPA and attenuated accompanying platelet activation, including intracellular calcium mobilization, granule secretion, and adhesion receptor expression. The anti-SIPA effect of PCA was mediated through blockade of von Willebrand factor binding to activated glycoprotein Ib, a primary and initial event for the accomplishment of SIPA. Conspicuously, PCA did not inhibit platelet aggregation induced by other endogenous agonists like collagen, thrombin, or ADP that are important in both pathological thrombosis and normal hemostasis. Antithrombotic effects of PCA were confirmed in vivo in a rat arterial thrombosis model, where PCA significantly delayed the arterial occlusion induced by FeCl3. Of particular note, PCA did not increase bleeding times in a rat tail transection model, whereas conventional antiplatelet drugs, aspirin, and clopidogrel substantially prolonged it. Collectively, these results suggest that PCA may be a novel antiplatelet agent that can prevent thrombosis without increasing bleeding risks.
Footnotes
This work was supported by the National Research Foundation of Korea, which is funded by the Korean government [Grant 20120000844].
Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
ABBREVIATIONS:
- SIPA
- shear stress-induced platelet aggregation
- Ab
- antibody
- AM
- acetoxymethyl ester
- FITC
- fluorescein isothiocyanate
- GP
- glycoprotein
- LDH
- lactate dehydrogenase
- PCA
- protocatechuic acid
- PE
- phycoerythrin
- PGE1
- prostaglandin E1
- PRP
- platelet-rich plasma
- vWF
- von Willebrand factor
- WP
- washed platelet.
- Received July 8, 2012.
- Accepted September 4, 2012.
- Copyright © 2012 by The American Society for Pharmacology and Experimental Therapeutics
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