Two New Taxane Diterpenoids From Taxus baccata

Two new diterpenoids named 13-oxo-wollifoliane-10,15-olide (1) and 19-acetoxy-7,9,10-deacetyl-baccatin VI (2), along with 14 known taxanes (3-16), were isolated from Taxus baccata. The structures of these compounds were elucidated by 1-dimensional and 2-dimensional nuclear magnetic resonance spectra, high-resolution electrospray ionization-mass spectrometry, and infrared spectroscopy. Structurally, 13-oxo-wollifoliane-10,15-olide (1) is the first taxane diterpenoid possessing an unusual carbonyl group at the C-13 position of the 11(15→1),11(10→9)bis- abeo-taxane structure (5/6/6/6/4 skeleton), and 19-acetoxy-7,9,10-deacetyl-baccatin VI (2) is a new compound containing an acetoxy group at the C-19 position of 6/8/6/4-taxane. Among the 14 known taxane compounds 3-16, compounds 7 and 9 were first isolated and reported from T. baccata. Several compounds (3-16) were evaluated for cytotoxicity against MCF-7 and HCT116 human cancer cell lines, but none of them showed considerable cytotoxic activity.