Manoyl oxide alpha-arabinopyranoside and grindelic acid diterpenoids from Grindelia integrifolia.

Two new manoyl oxide-alpha-arabinopyranoside diterpenoids, 15-hydroxy-13-epi-manoyl oxide-14-O-alpha-L-arabinopyranoside (tarapacol-14-O-alpha-L-arabinopyranoside) (1) and 15-acetoxy-13-epi-manoyl oxide-14-O-alpha-L-arabinopyranoside (tarapacol-15-acetate-14-O-alpha-L-arabinopyranoside) (2), as well as a new grindelic acid derivative, 19-hydroxygrindelic acid (3), together with five known diterpenoids (tarapacol, tarapacanol A, grindelic acid, methyl grindeloate, 3beta-hydroxygrindelic acid, 4) were isolated from the aerial parts of Grindelia integrifolia. The structures of 1-3 were elucidated by spectral data analysis.