New Eremophilane-Type Sesquiterpenes from Ligularia lapathifolia

Abstract

Seven new eremophilanolides were isolated from the roots and rhizomes of Ligularia lapathifolia. Their structures were established as 3β-angeloyloxy-8βH-eremophil-7(11)-ene-12,8α (14β, 6α)-diolide, 3β-angeloyloxy-8β-hydroxyeremophil-7(11)-ene-12,8α(14β,6α)-diolide,3β-angeloyloxy-8β-methoxyeremophil- 7(11)-ene-12,8α(14β,6α)-diolide,3β-angeloyloxy-8β-ethoxyeremophil-7(11)-ene-12, 8α (14β,6α)-diolide, 3β-angeloyloxy-10β- hydroxyeremophil-8(9),7(11)-diene-12,8(14β,6α)-diolide, 3β-angeloyloxy-8,12-expoy-12α-hydroxy-8β-methoxyeremophil-7(11)-en-14β,6α-olide and 3β-angeloyloxyeremophilan-7,11-dien-14β,6α-olide, by means of spectroscopic analyses. Moreover, application of a photooxygenation reaction on 7 resulted in the generation of 2 with an α,β-unsaturated γ-lactone moiety. This biomimetic transformation supports a biogenetic pathway proposed for 2.

Key words

Ligularia lapathifolia - Asteraceae - eremophilane-type sesquiterpenes - photooxygenation

References

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