Two new compounds from Crataegus pinnatifida and their antithrombotic activities

One new sesquiterpene, (1α,4aβ,8aα)-1-isopropanol-4a-methyl-8-methylenedecahydronaphthalene (1), with one new phenylpropanoid, threo-2-(4-hydroxy-3,5-dimethoxyphenyl)-3-(4-hydroxy-3-methoxyphenyl)-3-ethoxypropan-1-ol (2), along with four known phenylpropanoids were isolated from Crataegus pinnatifida. The structures of compounds 1 and 2 were elucidated on the basis of 1D, 2D NMR analyses, and HR-ESI-MS. The antithrombotic activity in vitro of all isolates was assayed, and only compound 1 exhibited potent antithrombotic activity by inhibiting platelet aggregation in rat plasma by 81.4% at 1 mg/ml.