Sesquiterpene Lactones From Onopordum Ambiguum

The aerial parts of Onopordum ambiguum afforded a new dihydroxylated sesquiterpene lactone, namely, 8 alpha-[4-hydroxymethacryloyloxy]-1-epi-sonchucarpolide [1], a C-1 epimer of a perviously isolated eudesmanolide, in addition to the known germacranolide, onopordopicrin [2]. The known flavonoid 5,7,3',4'-tetrahydroxy-3-methoxyflavone was also isolated and characterized. The structure elucidation of the new compound was based primarily on 1D and 2D-NMR analyses