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-4 H-dibenzo[ de,g]quinoline-4,5-(6 H)-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 and eugenol acetate exhibit stronger anti-platelet aggregation activities induced by arachidonic acid than 4-allylcatechol and eugenol, respectively.