167
3.25 Ligularia cymbulifera (W. W. Smith) Handel-Mazzetti
Ligularia cymbulifera is a very abundant species in the Shangri-La area, Yunnan Province,
China (Plate 18, Table 30). Initially, 13 samples were collected in Shangri-La and adjacent counties. No intraspecific diversity in chemical composition was observed by TLC
analysis. The extracts of two samples (samples 1 and 2) were worked up to isolate eremoligenol (14), tetradymol (225), and the furanoeremophilan- 15,6-olides 215, 222, and
224 [48]. In addition to these compounds, a simple eremophilane (26) and seven eremophilanolides (389, 393, 394, 441 (Sect. 3.1), 498, 561, and 562), including their derivative 146, were isolated in a detailed study (sample 8) [49]. Furanoeremophilanes 191,
201, 203, and 204 (from samples 6 and 7) [128] and other terpenoids, ligulacymirins A
(592), B (593), 813, and 866 (from sample 9) [147], were also recorded. Ligulacymirins
(592 and 593) have an interesting 19-carbon skeleton, for which their structures were
determined by X-ray crystallographic analysis. Their plausible biosynthesis pathways are
illustrated in Fig. 74. Among these compounds, tetradymol (225) is the major component
and is considered to be a phytotoxin to prevent the growth of other plants [147].
Plate 18 Photograph of
L. cymbulifera
Fig. 74 Plausible mechanism for the formation compounds 592 and 593
Chemical Constituents of Ligularia Species (Asteraceae) and Their Diversity…
3.25 Ligularia cymbulifera (W. W. Smith) Handel-Mazzetti
Ligularia cymbulifera is a very abundant species in the Shangri-La area, Yunnan Province,
China (Plate 18, Table 30). Initially, 13 samples were collected in Shangri-La and adjacent counties. No intraspecific diversity in chemical composition was observed by TLC
analysis. The extracts of two samples (samples 1 and 2) were worked up to isolate eremoligenol (14), tetradymol (225), and the furanoeremophilan- 15,6-olides 215, 222, and
224 [48]. In addition to these compounds, a simple eremophilane (26) and seven eremophilanolides (389, 393, 394, 441 (Sect. 3.1), 498, 561, and 562), including their derivative 146, were isolated in a detailed study (sample 8) [49]. Furanoeremophilanes 191,
201, 203, and 204 (from samples 6 and 7) [128] and other terpenoids, ligulacymirins A
(592), B (593), 813, and 866 (from sample 9) [147], were also recorded. Ligulacymirins
(592 and 593) have an interesting 19-carbon skeleton, for which their structures were
determined by X-ray crystallographic analysis. Their plausible biosynthesis pathways are
illustrated in Fig. 74. Among these compounds, tetradymol (225) is the major component
and is considered to be a phytotoxin to prevent the growth of other plants [147].
Plate 18 Photograph of
L. cymbulifera
Fig. 74 Plausible mechanism for the formation compounds 592 and 593
Chemical Constituents of Ligularia Species (Asteraceae) and Their Diversity…