Pterisolic Acids A—F, New ent-Kaurane Diterpenoids from the Fern Pteris semipinnata

Abstract

Six new ent-15-oxokauran-19-oic acid derivatives, named pterisolic acids A—F (1—6), were isolated from the ethanol extract of the fern Pteris semipinnata (Pteridaceae), and the structures of these new ent-kauranoids were elucidated on the basis of extensive spectroscopic studies and single crystal X-ray diffraction analysis.