Hot Water Extracts of the Royal Sun Mushroom, Agaricus brasiliensis (Higher Basidiomycetes), Inhibit Platelet Activation via the P2Y1 Receptor.

Hot water extracts of the medicinal mushroom Agaricus brasiliensis were investigated for their inhibition of platelet aggregation. The extracts significantly inhibited human platelet aggregation induced by adenosine 5'-diphosphate (ADP), but not by collagen or thrombin receptor-activating peptide. The extracts also had a significant inhibitory effect on shape change and intracellular calcium mobilization induced by ADP via inhibition of ADP binding to the P2Y1 receptor. In addition, oral administration of the extracts resulted in prolonged tail bleeding time in mice. The marked antiplatelet activity of the mushroom extracts involving the P2Y1 receptor suggests their potential therapeutic use against vascular disorders.