A new demethyl abietane diterpenoid from the roots of Tripterygium wilfordii

A new demethyl abietane diterpenoid, Triptotin K (3) together with three known compounds, friedelin (1), canophyllal (2), and triptonoterpene (4) were isolated from the roots of Tripterygium wilfordii Hook. f. by silica gel column and preparative high performance liquid chromatography. Their structures were determined by extensive NMR data and mass spectroscopic analysis. Triptotin K showed cytotoxic activities against KB, KBv200, HepG2, and MCF-7/ADM cells lines with IC₅₀ values of 29.88, 36.50, 39.55, and 41.38 μM, respectively.