Bioassay-directed fractionation of an ethanolic extract of stems of Vernonia cinerea has resulted in the isolation of two novel sesquiterpene lactones, vernolide-A and -B. Their structures were elucidated on the basis of spectroscopic analysis. Biological evaluation showed that vernolide-A demonstrated potent cytotoxicity against human KB, DLD-1, NCI-661, and Hela tumor cell lines (ED50=0.02, 0.05, 0.53, 0.04 μg/ml for KB, DLD-1, NCI-661, and Hela, respectively); vernolide-B had marginal cytoxicity (ED50=3.78, 5.88, 6.42 μg/ml for KB, NCI-661, and Hela, respectively).

The C18 dibenzocyclooctadiene lignans including three novel schizanrin F (1), G (2), H (3), along with the known kadsurarin (4), were isolated from Kadsura matsudai. A new C19 homolignan named schiarisanrin E (5), together with the known C18 lignans, gomisin B (6), G (7) and (+)-gomisin K3 (8) were obtained from Schizandra arisanensis. Gomisin B, G and (+)-gomisin K3 showed moderate to strong activity for antihepatitis in anti-HBsAg (human type B hepatitis, surface antigen) and/or anti-HBeAg (human type B hepatitis, e antigen) tests. The structural elucidations of new compounds 1—3 and 5 were based on two-dimensional (2D) NMR techniques including COSY, HMQC, HMBC, NOESY and CD spectra. Preliminary structure–activity relationship studies for these isolated lignans are also discussed.