Weitere Helenanolide aus den Blüten vonArnica chamissonissubsp.foliosa1,2,3

Abstract
A phytochemical study of the flowers of Arnica chamissonis Less. subsp. foliosa (Nutt.) Maguire (Asteraceae) has resulted in the identification of a further 23 helenanolides. Six of them, 2α-hydroxy-6-O-angelicoyl-2,3-dihydrohelenalin (3b), 2α-hydroxy-6-O-senecioyl-2, 3-dihydrohelenalin (3c), 2α-hydroxy-6-O-tigloyl-2,3,11α,13-tetrahydrohelenalin (4a), 2α-hydroxy-6-O-isovaleryl-2, 3,11α,13-tetrahydrohelenalin (4d), 6-O-acetylchamissonolide (5c), and 4,6-di-O-acetylchamissonolide (5d), were isolated for the first time as natural compounds. Their structures were established by GLC-MS studies and IR, 1H- and 13C-NMR spectroscopy