Vieloplains A-G, seven new guaiane-type sesquiterpenoid dimers from Xylopia vielana.

Seven new guaiane-type sesquiterpene dimers vieloplains A-G, connecting patterns through three different direct CC bonds compounds 1-5 (C-3 to C-3', C-4 to C-1'), compound 6 (C-2 to C-3', C-4 to C-2') and compound 7 (C-2 to C-1', C-4 to C-2') were isolated from the roots of Xylopia vielana. Their absolute configurations were established by NOESY analysis, the Cu Kα X-ray crystallographic the experiment circular dichroism (ECD) and the calculated ECD. Among them, only compound 6 showed a considerable cytotoxicity against DU145 cells with IC50 values of 9.5 μM. Flow cytometry analysis confirmed that 6 caused death of DU145 cells via apoptosis induction.