Cytotoxic and anticoagulative diterpenoid glycosides from Pteris decrescens.

Diterpenoids from the genus Pteris have demonstrated consistent anticancer properties. In the present study, five previously undescribed (1-5) and four known diterpenoids (6-9) were isolated from the 95 % methanol extract of P. decrescens. Among them, decrescensin A (1), represents the first naturally occurring example of a 15(8 → 9)-abeo-ent-kauranoid. The structures of these compounds were established based on their spectroscopic data and single-crystal X-ray diffraction. Compounds 1-9 have been evaluated for their cytotoxic effects against a panel of cancer cell lines including HeLa, HepG2, A549 and SW480. Compound 1 showed significant activity in SW480 cells with an IC50 value of 0.46 μM. In addition, compounds 4 and 6 displayed a mild prolongation effect on activated partial thromboplastin time.