Lindera cyclopentenedione intermediates from the roots of Lindera aggregata

Chromatographic fractionation of the roots of Lindera aggregata has led to the isolation of three new monomers of Lindera cyclopentenedione derivatives (1-3), a pair of new enantiomers of bi-linderone derivatives (4a/4b), and six known Lindera 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 in vivo biosynthesis of the monomers of Lindera cyclopentenediones. A possible biosynthetic pathway for 1 and a plausible biosynthetic pathway from stilbenes to Lindera cyclopentenediones via the key intermediates 2 and 3 were postulated. The inhibitory activity of these compounds against three microorganisms was also evaluated.