Isolation and absolute configuration of ent-Halimane diterpenoids from Hymenaea courbaril from the Suriname rain forest.

Bioactivity-directed fractionation of a methanol extract of Hymenaea courbaril afforded the three new diterpenoids (13R)-13-hydroxy-1(10),14-ent-halimadien-18-oic acid (1), (2S,13R)-2,13-dihydroxy-1(10),14-ent-halimadien-18-oic acid (2), and (13R)-2-oxo-13-hydroxy-1(10),14-ent-halimadien-18-oic acid (3). The configurations of these compounds were determined from X-ray crystallography of 1, circular dichroism of 2 and 3, and spectral studies of prepared derivatives. Compound 1 exhibited weak cytotoxicity toward the 1138 mutant yeast strain and the A2780 human ovarian cancer cell line.