Lignans from Schisandra propinqua with inhibitory effects on lymphocyte proliferation

Seven new dibenzocyclooctadiene lignans, named propinquain E-K, together with 11 known lignans were isolated from the ethanol extract of the roots of Schisandra propinqua subsp. sinensis. The structures of the new compounds were elucidated by spectroscopic methods, including ¹H- and ¹³C-NMR, 2D-NMR, HR ESI-MS, and CD spectra. Two dibenzocyclooctadienes revealed inhibitory effects on lymphocyte proliferation.