Chemical constituents of Nouelia insignis Franch.

Two new diterpenes and ent-15alpha-hydroxykaur-16-en-19-oic acid 11,12-acetonide (3), together with 23 known compounds were isolated from the dried aerial parts of Nouelia insignis Franch. The structures of new compounds were determined to be ent-14beta,15alpha-dihydroxykaur-16-en-19-oic acid (1), ent-14beta-hydroxy-15-oxokaur-16-en-19-oic acid (2) on the basis of spectral and chemical evidence. The structure of ent-11alpha,16alpha-epoxy-15alpha-hydroxy-16S-kaur-19-oic acid (4) was confirmed by X-ray crystallographic analysis.