We studied the content of cytotoxic compounds from Zuelania guidonia (Flacourtiaceae) leaves collected in Santa Rosa, Guanacaste (Costa Rica). We isolated
two labdanes (1,2) and twenty clerodanes (3–22), sixteen of which have not been previously reported. Interestingly, clerodane glycosides
are described for the first time in this family. The isolation was carried out using
HPLC techniques and the structural elucidation was performed with 1D and 2D NMR and
mass spectrometric techniques. The absolute stereochemistry of the elucidated clerodanes
was proposed to be 5S, 8R, 9R and 10S based on previous X-ray studies for compounds
from this family. The relative stereochemistry of the remaining chiral carbons was
determined using NOE and 13C-NMR spectroscopy.
