cyclopentenedione intermediates from the roots of .

Chromatographic fractionation of the roots of has led to the isolation of three new monomers of cyclopentenedione derivatives (1-3), a pair of new enantiomers of bi-linderone derivatives (4a/4b), and six known cyclopentenediones (5-8 and 9a/9b). Their structures were determined by NMR and MS data. The absolute configurations of the new bi-linderone derivative enantiomers (4a/4b) were determined by ECD calculation. (±)-Lindepentone A (1) presents the novel skeleton of 3,5-dioxocyclopent-1-enecarboxylate. Lindoxepines A (2) and B (3) present an unprecedented oxepine-2,5-dione derivative skeleton, which may be enlightening for the biosynthesis of the monomers of cyclopentenediones. A possible biosynthetic pathway for 1 and a plausible biosynthetic pathway from stilbenes to cyclopentenediones the key intermediates 2 and 3 were postulated. The inhibitory activity of these compounds against three microorganisms was also evaluated.