A new lignan, named schisantherin A, has been isolated from the fruits of Hua-Zhong-Wu-Wei-Zi(Schisarndra sphenanthera Rehd et Wils) (Magnoliaceae).According to the pharmacological and preliminary clinical findings, the schisantherin A is one of the antihepatotoxic principle of this plant.It is a lignan unknown so far.The molecular formula of schisantherin A is found to be C₃₀H₃₂O₉ by mass spectroscopit and elementary analyses.When treated with 10% potassium hydroxide in methanol, it was converted into the corresponding hydroxy compound, schisantherinol A (C₂₃H₂₈O₈) and benzoic acid in high yields.By taking advantage of UV, IR,NMR and mess spectroscopy, the structures of the two compounds, schisantherin A and schisantherinol A, are shown to be Ⅰ_a and Ⅰ_b respectively.Finally, the structure including the positions of all of the functional groups and conformation of sohisantherin A is established by double resonance experiments and measurements of intramolecular nuclear Overhauser effects (NOE).The resints are shown in Ⅱ.