Two undescribed compounds from Silybum marianum and their cytotoxicity activities

A new amide dimer (1), a new labdane-type diterpene (2), and 18 known compounds were isolated from the seeds of Silybum marianum (L.) Gaertn. The structures of the new compounds were elucidated by extensive spectroscopic data analyses and comparison with previously reported spectral date. The absolute configurations of compound 2 was established by analysis of the electronic circular dichroism (ECD) data. In vitro bioassays, none of them were cytotoxic to 4T1, but five compounds exhibited cytotoxicity to LN229 cells with IC50<25 mu M.