16-tetranorlabdane-8α, 12, 14-triol (2), as well as an acetylated derivative, 8α-O-β-d-
glucopyranosyllabd-13 E-ene-15, 19-diol-8α-2′, 3′, 4′, 6′-hexaacetate (3a), were
isolated from the aerial parts of Crassocephalum mannii. The structures of 1, 2, and 3a were
elucidated by spectroscopic data analysis. Selective inhibitory activity for 1 and 2 and their
acetate derivatives, 1a and 2a, against cyclooxygenases (COX-1 and COX-2) was detected.