Abstract
From the fronds of Pteris longipes DON two known and five new ent-kaurane type diterpenes were isolated. The structures of the new diterpenes, pterokaurene L1, L2, L3, L4 and pterokaurane L5, were established respectively as ent-9-hydroxy-15-oxo-kaur-16-en-19-oic acid, ent-9, 15α-dihydroxy-kaur-16-en-19-oic acid, ent-9-hydroxy-kaur-16-en-19-oic acid, ent-12α, 15α-dihydroxy-kaur-16-en-19-oic acid and ent-11α, 16α-epoxy-16R-kauranoic acid by spectroscopic methods, some chemical transformations and X-ray crystallographic analysis.