evaluation of their pharmacological activities. These compounds showed significant inhibition of plateletaggregation and some of them possessed a protective against endothelial cell injury. Structure-activity relationship studies indicated that 2b, 2d and 3b are potent inhibitors of plateletaggregation induced by arachidonic acid (AA) with an IC50 in the range of 1-10 micrograms/ml. Among them, 3b