Eremophilane-type Sesquiterpenes from the Leaves of Ligularia Virgaurea

Abstract

A phytochemical study of the ethanolic extract of the leaves of Ligularia virgaurea led to the isolation of a new eremophilane-type sesquiterpene lactone, (4 S,5 R,6 S,8 S,10 R)–6β-angeloyloxy-eremophil-7(11)-en-10βH-8α,12-olide (1), along with a known eremophilane-type sesquiterpene, (4 S,5 R,6 S,10 S)–6β-angeloyloxy-10βH-furanoeremophil-9-one (2). Their structures were elucidated by extensive spectroscopic methods, including 1D and 2D nuclear magnetic resonance and high-resolution electrospray ionization mass spectrometry experiments, and the absolute configurations were confirmed by single-crystal X-ray diffraction analysis using the anomalous scattering of Cu Kα radiation.