A new aristolactam alkaloid and anti-platelet aggregation constituents from Piper taiwanense

A new alkaloid, piperolactam E, and fourteen known compounds have been isolated from the stem of Piper taiwanense. Bioassay guided fractionation of the methanolic extract led to the isolation, from the chloroform-soluble part, of 4-allylcatechol, eugenol, trans-caffeic aldehyde, 2-hydroxy-1-methoxy-4H-dibenzo[de,g]quinoline-4,5-(6H)-dione, piperolactam B, piperolactam C, and piperolactam E as the active principles of anti-platelet aggregation in vitro. The derived 1,2-diacetoxy-4-allyl-benzene an eugenol acetate exhibit stronger anti-platelet aggregation activities induced by arachidonic acid than 4-allylcatechol and eugenol, respectively.