<i>Lindera</i> cyclopentenedione intermediates from the roots of <i>Lindera aggregata</i>

Abstract

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