Platelet anti-aggregating activities of bupleurumin from the aerial parts of Bupleurum falcatum.

An aryltetralin lactone, (-)-(1S,2R,3R)-1-(3',4'-methylenedioxyphenyl)-3-(hydroxymethyl)-6,7-dimethoxy-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid lactone, was isolated from the methanol extract of the aerial parts of Bupleurum falcatum and named bupleurumin. The structure of the compound was determined on the basis of chemical and spectroscopic methods, including two-dimensional NMR spectrometry (e.g., 1H- and 13C-NMR, homo- and heteronuclear COSY, HMBC). Bupleurumin showed an 8-fold potent inhibitory effect (IC50: 47.5 uM) compared to that of acetylsalicylic acid (ASA, IC50 : 420 uM) on collagen induced platelet aggregation and comparable effects as ASA on arachidonic acid-induced platelet aggregation.