Dibenzocyclooctadiene lignans from Kadsura heteroclita.

Sixteen dibenzocyclooctadiene lignans, including eight new ones, kadheterins A-H (1-8), and a new natural product, 9-benzoyloxy-gomisin B (9), were isolated from the stems of K. heteroclita. The structures of 1-9 were elucidated by extensive spectroscopic methods, and their absolute configurations were determined by combining CD with ROESY experiments. Additionally, the absolute configuration of 1 was further confirmed by single crystal X-ray crystallographic analysis. In vitro activity assays showed that 1 exhibited moderate cytotoxicity against HL-60 with IC50 value at 14.59μM.