Bioactive dibenzocyclooctadiene lignans from the stems of Schisandra neglecta

Seven new unusual dibenzocyclooctadiene Lignans, neglignans A-G (1-7), together with 16 known dibenzocyclooctadiene Lignans, were isolated from the stems of Schisandra neglecta. Compounds 1 and 2 are the first dibenzocyclooctadiene Lignans bearing a carboxyl group at C-4, and compounds 3 and 4 are the first 7,8-seco-dibenzocyclooctadiene Lignans found from Nature. The new compounds (1-7) and several of the known compounds were evaluated for their anti-HIV activity and cytotoxicity. Compounds 2 and 6 showed anti-HIV-1 activities with therapeutic index values greater than 50, and compound 4 showed cytotoxicity against the NB4 and SHSY5Y Cancer cell lines with IC50 values of 2.9 and 3.3 μM, respectively.