129
Sample 2 (Lhünzê, Tibet Autonomous Region, China) produced quite different
compounds from those of sample 1. A number of flavones (919, 920, 1025, 1026,
1027, and 1028) and two lactones (891 and 892) were isolated [255]. The absolute
configurations of compounds 891 and 892 were determined by ECD spectroscopy.
However, a NOE between H 3 -7 and H-10β for the conformation indicated in the
literature was difficult to detect due to the large intramolecular distance involved
Fig. 53 Other sesquiterpenoids
Chemical Constituents of Ligularia Species (Asteraceae) and Their Diversity…
Sample 2 (Lhünzê, Tibet Autonomous Region, China) produced quite different
compounds from those of sample 1. A number of flavones (919, 920, 1025, 1026,
1027, and 1028) and two lactones (891 and 892) were isolated [255]. The absolute
configurations of compounds 891 and 892 were determined by ECD spectroscopy.
However, a NOE between H 3 -7 and H-10β for the conformation indicated in the
literature was difficult to detect due to the large intramolecular distance involved
Fig. 53 Other sesquiterpenoids
Chemical Constituents of Ligularia Species (Asteraceae) and Their Diversity…