Lancolides, Antiplatelet Aggregation Nortriterpenoids with Tricyclo[6.3.0.02,11]undecane-Bridged System from Schisandra lancifolia

A new class of highly oxygenated Schisandra nortriterpenoids, lancolides A–D (1–4), from Schisandra lancifolia, represents the first example of natural products that possess a tricyclo[6.3.0.02,11]undecane-bridged system. Their structures were elucidated by NMR spectra, X-ray diffraction, and quantum chemical calculations. Lancolides A (1) and D (4) had specific antiplatelet aggregation induced by platelet-activating factor (PAF).