Four Lignans from Syringa pinnatifolia and Their Antioxidant Activity

n investigation of ethyl acetate extracts from Syringa pinnatifolia has led to the isolation of one new lignan ( 1 ) together with three known compounds ( 2–4 ). The structures of compounds 1–4 were identified by UV, IR, ESI-MS, and 1D NMR and 2D NMR. 2,2-Diphenyl-1-picryhydrazyl (DPPH) was used to evaluate the antioxidant activity of the compounds for the radical scavenging capacity. All of the compounds showed strong antioxidant activity.