161
ligularol-type of samples (samples 8–10), fukinone (4), 160, ligularol (161), 163,
ligularone (168), 225, and bakkenolide A (629) were isolated [37]. From the
furanoeremophil- 1(10)-ene-type of samples (samples 4 and 5), both 1(10)-enes
(250, 254, 256, and 257) and 1,10-epoxides (287, 289, 290, 291, 293, and 330) were
apparent [37, 155]. Compounds 163 and 330 were deemed as artifacts, as produced
during extraction with EtOH.
Additional eremophilanes and other compounds have been isolated from L. fischeri samples collected at different locations. From sample 2 (obtained in Jilin Province,
China), furanoligularenone (268), and compounds 412, 413, 447, 450, 451, 452, and
554, fischerisins A (575) and B (576), fischelactone B (577), fischelactone (578), and
compounds 579 and 580 were isolated, together with the triterpenoid 837 [158, 210–
212]. Compounds 577, 578, 579, and 580 were characterized as dimeric lactones.
From samples 12–14 (from Hubei Province, China), eremophilanes 17, 27, 344, 346,
356, 359, 361, 363, 364, 365, and 556 were produced [54, 179, 185]. An aromadendrane (787) and three eudesmanes (795, 798, and 799) were also obtained from the
same sample [54]. The eremophilane composition of samples 3 and 19 from
Chongqing City, China, proved to be somewhat different from those of the other
specimens examined. From samples 3 and 19, the noreremophilanes 94, 119, 120,
121, 122, 135, 137, and 138 and the highly functionalized furanoeremophilanes 241,
242, and 306 occurred [85, 96, 165]. Compounds 241 and 242 were assigned structurally as chlorinated furanoeremophilanes (sample 3) [188]. Two bakkane compounds, 644 and 645 [165], and an aromatic compound, 951 [85], were also obtained.
Only the eremophilan-8-one derivatives 2, 5, 48, 50, 54, 56, and 60 were obtained
from sample 20 (from Henan Province, China) [30], while eremophilanolides 421,
422, 431, and 432 and the noreremophilane 140 were obtained from a commercial
Chinese medicine (sample 15) [110]. From sample 21 (Shaanxi Province, China), the
eremophilanolides 344, 345, 346, 356, 359, 360, 361, 389, 393, 435, 447, and 556
were isolated together with compounds 26 and 120 and bakkenolide A (629) [58].
From the same sample, the aromatic derivatives 901, 916, 1010, 1019, 1020, 1021,
1027, 1033, 1034, and 1045 were also purified [257]. Sample 22 from Shanxi
Province, China, produced only diterpenoids [246], comprising fischericins A (815),
B (816), C (817), D (818), E (819), and F (820), as well as other ent-kaurane-type
diterpenoids (821, 822, 823, 824, 825, and 826) and a labdane-type diterpenoid
(827). Interestingly, no sesquiterpenoids at all were detected in this sample.
Secondary metabolites in Korean samples were also studied (samples 16–18).
From these, eremophilanolides (366, 451, and 452), a furanoligularenone (268), a
eudesmane (792), and linear hydrocarbons (885, 887, and 888) were isolated [157,
187, 188]. These studies indicate that the widely distributed L. fischeri produces
eremophilanes as the major components but is highly diverse in its chemical
composition.
The chemical composition of L. anoleuca has been reported by only our group
and was found to be close to the furanoeremophil-1(10)-ene type of L. fischeri.
From six samples of L. anoleuca, furanoeremophil-1(10)-enes 249, 256, 262, 263,
264, 265, 266, 267, and 271 and 1,10-epoxyfuranoeremophilanes 291, 295, 298,
299, 300, and 302 were isolated. Furanoligularenone (268), a related 1-en-3-one,
was also obtained (Table 27) [154, 155].
Chemical Constituents of Ligularia Species (Asteraceae) and Their Diversity…
ligularol-type of samples (samples 8–10), fukinone (4), 160, ligularol (161), 163,
ligularone (168), 225, and bakkenolide A (629) were isolated [37]. From the
furanoeremophil- 1(10)-ene-type of samples (samples 4 and 5), both 1(10)-enes
(250, 254, 256, and 257) and 1,10-epoxides (287, 289, 290, 291, 293, and 330) were
apparent [37, 155]. Compounds 163 and 330 were deemed as artifacts, as produced
during extraction with EtOH.
Additional eremophilanes and other compounds have been isolated from L. fischeri samples collected at different locations. From sample 2 (obtained in Jilin Province,
China), furanoligularenone (268), and compounds 412, 413, 447, 450, 451, 452, and
554, fischerisins A (575) and B (576), fischelactone B (577), fischelactone (578), and
compounds 579 and 580 were isolated, together with the triterpenoid 837 [158, 210–
212]. Compounds 577, 578, 579, and 580 were characterized as dimeric lactones.
From samples 12–14 (from Hubei Province, China), eremophilanes 17, 27, 344, 346,
356, 359, 361, 363, 364, 365, and 556 were produced [54, 179, 185]. An aromadendrane (787) and three eudesmanes (795, 798, and 799) were also obtained from the
same sample [54]. The eremophilane composition of samples 3 and 19 from
Chongqing City, China, proved to be somewhat different from those of the other
specimens examined. From samples 3 and 19, the noreremophilanes 94, 119, 120,
121, 122, 135, 137, and 138 and the highly functionalized furanoeremophilanes 241,
242, and 306 occurred [85, 96, 165]. Compounds 241 and 242 were assigned structurally as chlorinated furanoeremophilanes (sample 3) [188]. Two bakkane compounds, 644 and 645 [165], and an aromatic compound, 951 [85], were also obtained.
Only the eremophilan-8-one derivatives 2, 5, 48, 50, 54, 56, and 60 were obtained
from sample 20 (from Henan Province, China) [30], while eremophilanolides 421,
422, 431, and 432 and the noreremophilane 140 were obtained from a commercial
Chinese medicine (sample 15) [110]. From sample 21 (Shaanxi Province, China), the
eremophilanolides 344, 345, 346, 356, 359, 360, 361, 389, 393, 435, 447, and 556
were isolated together with compounds 26 and 120 and bakkenolide A (629) [58].
From the same sample, the aromatic derivatives 901, 916, 1010, 1019, 1020, 1021,
1027, 1033, 1034, and 1045 were also purified [257]. Sample 22 from Shanxi
Province, China, produced only diterpenoids [246], comprising fischericins A (815),
B (816), C (817), D (818), E (819), and F (820), as well as other ent-kaurane-type
diterpenoids (821, 822, 823, 824, 825, and 826) and a labdane-type diterpenoid
(827). Interestingly, no sesquiterpenoids at all were detected in this sample.
Secondary metabolites in Korean samples were also studied (samples 16–18).
From these, eremophilanolides (366, 451, and 452), a furanoligularenone (268), a
eudesmane (792), and linear hydrocarbons (885, 887, and 888) were isolated [157,
187, 188]. These studies indicate that the widely distributed L. fischeri produces
eremophilanes as the major components but is highly diverse in its chemical
composition.
The chemical composition of L. anoleuca has been reported by only our group
and was found to be close to the furanoeremophil-1(10)-ene type of L. fischeri.
From six samples of L. anoleuca, furanoeremophil-1(10)-enes 249, 256, 262, 263,
264, 265, 266, 267, and 271 and 1,10-epoxyfuranoeremophilanes 291, 295, 298,
299, 300, and 302 were isolated. Furanoligularenone (268), a related 1-en-3-one,
was also obtained (Table 27) [154, 155].
Chemical Constituents of Ligularia Species (Asteraceae) and Their Diversity…