Bioactive constituents of the roots of Licania intrapetiolaris

Fractionation of a methanol extract of the roots of Licania intrapetiolaris, as directed by activity against the KB assay, has led to the isolation of two novel clerodane diterpenoids, intrapetacins A (1) and B (2), and the known triterpenoid cucurbitacin B (3). The structures of 1 and 2 were deduced from one- and two-dimensional NMR experiments, including relative stereochemical assignments based on NOESY correlations and COSY coupling constants. Compound 3 was the most potent against the KB assay, but both 1 and 2 displayed moderate cytotoxicity. When evaluated against an antifungal assay using Aspergillus niger, 2 caused a significant zone of inhibition of fungal growth, while 1 was completely inactive. To the best of our knowledge, this is the first report of the isolation of bioactive compounds from the genus Licania.