An aqueous extract of guaraná (Paullinia cupana) decreases platelet thromboxane synthesis.

The effects of an aqueous extract of guaraná (Paullinia cupana) on rabbit platelet aggregation and thromboxane synthesis were examined. The guaraná extract (100 mg/ml) and fractions separated by TLC (origin and xanthines) decreased platelet aggregation (37, 27 and 31% of control values, respectively) and platelet thromboxane formation from [14C]-arachidonic acid (78, 70 and 50% of control values, respectively). The decreased thromboxane synthesis could be responsible, at least in part, for the antiaggregatory action of guaraná.