Methods of prophylaxis or treatment of a disease state initiated by or characterized by platelet aggregation, that employ a fruit extract or active fraction thereof, are disclosed. In one embodiment, the fruit extract or active fraction thereof, is obtained from the fruit of plants of the families Solanaceae, Rutaceae, Cucurbitaceae, Rosaceae, Musaceae, Anacardiaceae, Bromeliaceae, Vitaceae, Arecaceae, Ericaceae and Lauraceae. Pharmaceutical compositions comprising a fruit extract or active fraction thereof having platelet aggregation inhibitory activity are also disclosed.