The inhibitory effect of Opuntia humifusa Raf. ethyl acetate extract on platelet aggregation

Abstract

This study was designed to investigate the activity of ethyl acetate extract from Opuntia humifusa Raf. (OH-EAE) in ligand-activated platelet aggregation. Platelet aggregation was induced either by ADP, a potent agonist to platelet G protein-coupled P2Y receptor, by collagen, a potent ligand that activates platelet integrin alpha 2 beta 1 and glycoprotein VI, or thrombin, a platelet protease-activated receptors subtype I and IV. The OH-EAE inhibited platelet aggregation induced by ADP (10 mu M) in a dose dependent manner. In addition, OH-EAE significantly and dose-dependently inhibited collagen (2.5 mu g/ml)- and thrombin (0.05 U/ml)-induced platelet aggregation. Moreover, the downstream signaling analysis revealed that the extract potently inhibited ADP-induced intracellular calcium mobilization ([Ca(2+)l(i)). Since degranulation is a marker of platelet activation, the extract effect on the dense granule secretary activity was evaluated. As such, OH-EAE strongly suppressed ADP-induced ATP release. This preliminary result suggests that O. humifusa may be taken as a candidate lead natural compound to be considered in the search for natural products with beneficial effects on aberrant platelet activation mediated cardiovascular disorders.