Twelve new compounds from Ligularia melanothyrsa; isolation of melanothyrsins A–E, normelanothyrsin A, and other eremophilane sesquiterpenoids

Twelve new compounds, namely, five melanothyrsins A-E (1 alpha-angeloyloxyeremophilenolides), normelanothyrsin A (1 alpha-angeloyloxynoreremophilenone), and six other eremophilane-type compounds, have been isolated from Ligularia melanothyrsa Hand.-Mazz. (Asteraceae), collected in the Sichuan Province of China. Six of the compounds have a 1 alpha-angeloyloxy moiety, while the other six have no functional group at the C-1 position. The absolute configuration was also determined using CD spectra. This is the first chemical study of compounds isolated from this species. (C) 2014 Elsevier Ltd. All rights reserved.