Licamichauxiioic-A and -B acids--two ent-kaurene diterpenoids from Licania michauxii.

Bioassay-guided fractionation allowed the isolation of two new cytotoxic ent-kaurene diterpenoids, licamichauxiioic-A and -B acids (1 and 2) from the root extract of Licania michauxii Prance (Chrysobalanaceae). They were characterized as ent-15-oxo-9(11),16-kauradien-19-oic acid (1) and ent-15-oxo-13(14),16-kauradien-19-oic acid (2) by various spectroscopic methods, in particular, 1D and 2D NMR spectra, and chemical evidence.