Labdane Diterpenes from Aster spathulifolius and Their Cytotoxic Effects on Human Cancer Cell Lines

Three new labdane diterpenes (<BO>1</BO>−<BO>3</BO>), together with eight known diterpenoids, were isolated from a methanol extract of the aerial parts of Aster spathulifolius. The structures of <BO>1</BO>−<BO>3</BO> were determined as (13R)-labda-7,14-diene 13-O-β-<SCP>d</SCP>-(4‘-O-acetyl)fucopyranoside (<BO>1</BO>), (13R)-labda-7,14-diene 13-O-β-<SCP>d</SCP>-(3‘-O-acetyl)fucopyranoside (<BO>2</BO>), and (13R)-labda-14(15)-en-8,13-diol 13-O-β-<SCP>d</SCP>-fucopyranoside (<BO>3</BO>), on the basis of spectroscopic and chemical methods. Compounds <BO>1</BO>, <BO>2</BO>, and four of the known compounds exhibited generally nonspecific cytotoxicity against human A549, SK-OV-3, SK-MEL-2, XF498, and HCT15 tumor cells.