New triterpenoids and a dibenzocyclooctadiene lignan from the leaves of Schisandra chinensis

Five schinortriterpenoids and seven lignans, were isolated from the leaves of Schisandra chinensis, including one undescribed schinortriterpenoid, schinensilactone C (1), one new lignan, schinlignan H (3), together with 20-epi-schilancitrilactone A (2) obtained as a natural product. Their structures were established by analysis of their spectroscopic data including MS, IR, 1D- and 2D NMR spectra. The absolute configuration of 1 was confirmed by single-crystal X-ray diffraction and that of the biphenyl ring in 3 was assigned by CD spectroscopy. Compounds 6, 9 and 11 are reported from Schisandra for the first time. All compounds were evaluated for their cytotoxic activity against LN299 cell line, (with doxorubicin as the positive control, IC50 = 0.49 μM), and compound 4 exhibited significant activity with an IC50 value of 0.36 μM.