7
2 Compounds
Most compounds reported from Ligularia spp. are sesquiterpenoids belonging to
the eremophilane, bakkane, oplopane, bisabolane, and eudesmane types. Only
minor amounts of germacrane, guaiane, aromadendrane, caryophyllane, valencane,
and cadinane types are produced. Cacalol and its derivatives have been categorized
within a separate cacalol group, in which the C-14 eremophilane methyl group is
shifted to the C-6 position. There has been some confusion in compound numbering
in the literature, particularly for the C-14 and C-15 methyl groups, and the numbering herein is that proposed by Connolly and Hill [16]. Plate 5 shows the major
skeletons and their numbering as used in this contribution. The structures drawn
show relative configurations, and absolute configurations are presented where they
have been determined. When X-ray structural analysis has been used, this is also
mentioned. Questionable structures that have been proposed are pointed out, as necessary. A total of 1049 compounds isolated from Ligularia spp. are listed in Table 1.
The plant sourcing for each compound is also listed in this table along with appropriate references. Structures of compounds isolated from Ligularia spp. are shown
in Figs. 1–72.
Plate 5 Skeletons of sesquiterpenoids isolated from Ligularia plants and their numbering
Chemical Constituents of Ligularia Species (Asteraceae) and Their Diversity…
2 Compounds
Most compounds reported from Ligularia spp. are sesquiterpenoids belonging to
the eremophilane, bakkane, oplopane, bisabolane, and eudesmane types. Only
minor amounts of germacrane, guaiane, aromadendrane, caryophyllane, valencane,
and cadinane types are produced. Cacalol and its derivatives have been categorized
within a separate cacalol group, in which the C-14 eremophilane methyl group is
shifted to the C-6 position. There has been some confusion in compound numbering
in the literature, particularly for the C-14 and C-15 methyl groups, and the numbering herein is that proposed by Connolly and Hill [16]. Plate 5 shows the major
skeletons and their numbering as used in this contribution. The structures drawn
show relative configurations, and absolute configurations are presented where they
have been determined. When X-ray structural analysis has been used, this is also
mentioned. Questionable structures that have been proposed are pointed out, as necessary. A total of 1049 compounds isolated from Ligularia spp. are listed in Table 1.
The plant sourcing for each compound is also listed in this table along with appropriate references. Structures of compounds isolated from Ligularia spp. are shown
in Figs. 1–72.
Plate 5 Skeletons of sesquiterpenoids isolated from Ligularia plants and their numbering
Chemical Constituents of Ligularia Species (Asteraceae) and Their Diversity…