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 (1α-angeloyloxyeremophilenolides), normelanothyrsin A (1α-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 1α-angeloyloxy moiety, while the other six have no functional group at the C-1 position. The absolute configuration...