Cumulative Data of 1H and 13C NMR Signals and Specific Rotations of Eremophilane Sesquiterpenoids. 1. Bicyclic Eremophilanes (1)

1H and 13C Nuclear Magnetic Resonance (NMR) signals and specific rotations of eremophilane sesquiterpenoids are cumulated as a series of review articles. In the first chapter of this review, 332 bicyclic eremophilanes, namely with no furan or lactone rings (except for epoxides), without 3-OR functionality (except for hydroxy, acetoxy, and carbonyl) are listed in tables. These data may help chemists working in the area of natural products chemistry as well as synthetic scientists.

Eremophilane Sesquiterpenoids and Nor- and Dinorsesquiterpenoids from Ligularia virgaurea Collected in China

Four samples of Ligularia virgaurea collected in China afforded three new eremophilane sesquiterpenoids, one new norsesquiterpenoid, and two new dinorsesquiterpenoids as well as 28 known compounds. All the four samples belonged to the ligularol type (L type), one of the five chemotypes we have described for this species. The configuration of the previously reported eremophila-7(11),9-dien-12,8-olide is revised to be H-8α. The absolute configuration of ethyl 8-oxoeremophila-7(11),9-dien-12-oate was established to be 4 S,5 R by a DFT calculation.

Eremophilanes from Ligularia hookeri Collected in China and Structural Revision of 3β-Acyloxyfuranoeremophilan-15,6-olide

Chemical constituents of Ligularia hookeri (Asteraceae) collected in Yunnan and Sichuan Provinces in China were examined for the first time. Seven furanoeremophilanes, five of which were new, as well as known bisabolane- and eudesmane-type sesquiterpenoids, were isolated. Spectroscopic evidence indicates that the previously reported 3β-(2'-methylpropenoyloxy)furanoeremophilan-15,6β-olide should be revised to 3β-(2'-methylpropenoyloxy)furanoeremophilan-15,6α-olide.

Chemical and Genetic Identity of Ligularia tsangchanensis and L. muliensis. Isolation of a Cacalol Precursor from a Hybrid of L. tsangchanensis and L. vellerea

The chemical composition and the DNA sequence of an evolutionarily neutral region were studied for three samples of L. tsangchanensis, three samples of L. muliensis, and one sample of a hybrid between L. tsangchanensis and L. vellerea. L. tsangchanensis and L. muliensis were indistinguishable in the chemical composition and the ITS sequence, supporting a recent taxonomic study that merged the two species into L. tsangchanensis. Cacalol (1) was isolated as the most major component from both L. tsangchanensis and L. muliensis, while 6-acetoxy-9-oxofuranoeremophilane (10), a putative cacalol precursor, was isolated from the hybrid.

A New Diterpenoid with a Rearranged Skeleton from Salvia prattii

A new diterpenoid with a rearranged skeleton, prattinin A (1), was isolated along with five known compounds (2–6) from the roots of Salvia prattii. The structure of 1 bearing a methyl group at the C-5 position was established by extensive spectroscopic analyses and the absolute configuration of 1 was elucidated by comparing the calculated and experimental electronic circular dichroism (ECD) spectra. Compounds 1, 3, 4, and 5 exhibited moderate or weak cytotoxicity against HL-60 and HeLa cell lines.

Chemical Diversity in Ligularia oligonema

The chemical composition of a sample of the title species collected in Pianma, Lushui County, Yunnan Province of China, was examined. Two 3,6,10-oxygenated and two 3,6-oxygenated furanoeremophilanes were isolated. Structures of two new compounds were elucidated. The 3,6-oxygenated furanoeremophilanes were not detected in a sample of the same species previously collected in Laojunshan, Jianchuan County, Yunnan, indicating chemical diversity in the species.

New Eremophilane-type Sesquiterpenes from Ligularia cymbulifera

From the roots of Ligularia cymbulifera collected in Yunnan Province, China, two new eremophilane-type sesquiterpenoids (1 and 2) together with ten known compounds (3–12) were obtained through the precise chemical component elucidation. The structure determination was mainly carried out with 1D and 2D NMR data.

Eremophilane-type Sesquiterpenes from the Leaves of Ligularia Virgaurea

A phytochemical study of the ethanolic extract of the leaves of Ligularia virgaurea led to the isolation of a new eremophilane-type sesquiterpene lactone, (4 S,5 R,6 S,8 S,10 R)–6β-angeloyloxy-eremophil-7(11)-en-10βH-8α,12-olide (1), along with a known eremophilane-type sesquiterpene, (4 S,5 R,6 S,10 S)–6β-angeloyloxy-10βH-furanoeremophil-9-one (2). Their structures were elucidated by extensive spectroscopic methods, including 1D and 2D nuclear magnetic resonance and high-resolution electrospray ionization mass spectrometry experiments, and the absolute configurations were confirmed by single-crystal X-ray diffraction analysis using the anomalous scattering of Cu Kα radiation.

[Diversity of Plants Belonging to the Genus Ligularia (Asteraceae) Based on Terpenoids and Synthetic Studies on Some Terpenoids]

The terpenoid constituents of Ligularia virgaurea (30 samples), Ligularia pleurocaulis (8 samples), Ligularia dictyoneura (8 samples), Ligularia brassicoides (5 samples), Ligularia lingiana (1 sample), and Ligularia liatroides (1 sample)(all belonging to section Senecillis of Ligularia, Asteraceae and collected in Yunnan, Sichuan, Qinghai, and Gansu provinces, China), from which 220 compounds were isolated, including 113 novel ones, are reviewed. Five chemotypes were identified in L. virgaurea based on their chemical constituents, while three clades were detected from the base sequences. Although intra-specific diversity was found in L. virgaurea, more samples were needed of other species in order to reach a definite conclusion. Inter-specific diversity was also examined in section Senecillis but was restricted due to the scarcity of samples. Synthetic studies on chiral natural products to determine their absolute configurations, especially those of riccardiphenols A and B as well as crispatanolide, which were all isolated from the liverwort, are briefly reviewed.

Terpenoid Composition and Base Sequences of Ligularia virgaurea (Asteraceae) Grown in the Hengduan Mountain Area in China and a Comment on Drawing Structures

A chemical analysis of 30 samples of Ligularia virgaurea (Asteraceae) collected in Sichuan province and its adjacent territories in China was reviewed. These samples afforded 146 compounds, 73 of which were novel, and the chemical constituents were classified into 8 categories: (1) simple eremophilanes (without ring C) and eudesmanes including nor-derivatives, (2) furanoeremophilanes and lactones with a 1(10)-saturated bond, (3) furanoeremophilanes and lactones with a 1(10)-unsaturated bond, 1,10-epoxide, or 10-ol, (4) furanoeremophilanes and lactones with 1(10)-en-2-one, 1(10)-en-2-ol, or 1-en-3-one, (5) furanoeremophilanes and lactones with 1(10)-en-9-one, 1(10)-en-9-ol, or 1,10-epoxy-9-one, (6) cacalol and their derivatives, (7) bakkanes and their derivatives, and (8) others, as shown in Tables 1-7. In these studies, five chemotypes were identified in addition to three clades from the DNA sequences of L. virgaurea. The structural determination of some compounds was also discussed and a comment on how to express the real structure was proposed, particularly for spiro compounds.

Chemical and Genetic Study of two Ligularia Hybrids in Shangrila County, Yunnan Province, China

The composition of root chemicals was examined for samples of L. cyathiceps × L. duciformis, L. duciformis × L. yunnanensis, and L. yunnanensis. Various furanoeremophilanes were isolated from a sample of L. cyathiceps × L. duciformis and found to be very similar to those isolated from L. cyathiceps. Lupeol and docosyl ferulate were isolated from L. yunnanensis, L. duciformis, and L. duciformis × L. yunnanensis.

Three New Eremophilanes from a Ligularia Hybrid Collected in China

Three new eremophilanes were isolated from a sample of Ligularia collected in Yunnan province of China and their structures were determined. The chemical constituents including eleven eremophilanes (major constituents: 6-acyloxyfuranoeremophilan-10β-ols) were similar to those of a hybrid of L. cyathiceps and L. subspicata, however, the base sequence of the ITS1-5.8S-ITS2 region was typical of L. cyathiceps, indicating backcrossing.

Chemical Lineages of Ligularia Fischeri

Six Ligularia fischeri samples, two from Sichuan (samples 1 and 2) and four from Chongqing (samples 3–6), were examined for root chemicals and the DNA sequence of the internal transcribed spacers of the ribosomal RNA gene. Samples 2 and 3 contained benzofurans. The isolation of benzofurans shows that the chemical diversity in L. fischeri is higher than previously reported. Samples 1, 4, 5, and 6 contained eremophilanes. However, the compounds were different between sample 1 and samples 4–6, indicating variation within eremophilane producers. DNA data indicated that introgression could be a mechanism of benzofuran production in sample 2 and that sample 1 and samples 4–6 were genetically separate.

Diversity in Chemical Constituents of Ligularia Longihastata Collected in China

Root constituents of Ligularia longihastata were examined for the first time. Fourteen eremophilane sesquiterpenes, including two new eremophilanes identified as 3α-isobutyroyloxy-7β H-eremophila-9,11-dien-8-one and 3β-angeloyloxy-1β,10β-epoxyfuranoeremophilan-9-one, and three eudesmanes were isolated. From samples collected in Baiyu County, Sichuan Province, furanoeremophilane derivatives were isolated, while various eremophilan-8-ones were isolated from samples collected in Kangding County, Sichuan. The results suggest chemical diversity in the species.

Two New Diterpenoids from Salvia Przewarskii

One abietane-type and one dinoricetexane-type diterpenoid, salviskin A (1) and salviskin B (2), respectively, together with fourteen known diterpenoids, were isolated from Salvia przewarskii. Structural elucidation of these compounds was performed by spectroscopic methods including 2D NMR. The compounds isolated were evaluated for their cytotoxicity against HeLa and HL-60 cells.

Chemical Constituents of Ligularia Wilsoniana Collected in Chongqing, China

The chemical constituents of Ligularia wilsoniana were studied for the first time, using four samples collected in Chongqing City, China. Two new compounds, 6β-(2′,3′-epoxy-2′-methylpropanoyloxy)-1β,10β-epoxyfuranoeremophilane and 11αH-6β-(2′-hydroxymethylacryloyloxy)-1β,10β;7β,8β-diepoxyeremophilanolide, as well as eight known compounds, were isolated from one of the samples, while three to four known furanoeremophilanes were isolated from the other three samples. No compound was common to the two classes of the samples, demonstrating the presence of at least two chemotypes of this species.

Two New Eremophilane Sesquiterpenes and One New Resorcinol from Ligularia Knorringiana

Two new eremophilane sesquiterpenes, 12-oxa-1β, 5β,8,9aβ-tetramethyl-4α,5-ethano-4aβ-hydroxy-7β,10aβ-epoxy-9β-angeloyloxy-1,2,3,4,4a,5,6,7,9,9a,10,10a-dodecahydro-anthracen-13-on (knorringianalarin A, 1) and 6,9-dien-8-oxoeremophil-12-nor-11-ketone (knorringianalarin B, 2), and a new resorcinol, 4-acetyl-6-(2-methylpropionyl)-1,3-resorcinol (knorringianalarin C, 3) were isolated from the roots and rhizomes of Ligularia knorringiana, together with three known eremophilane sesquiterpenes (4–6). The structures of the new compounds were identified by spectroscopic methods including 2D-NMR techniques.

Chemical and Genetic Diversity of Ligularia hodgsonii in China

Ligularia hodgsonii was found to be diverse in China. Furanoeremophilanes were isolated from samples collected in Yunnan Province, while such compounds were absent from samples from Sichuan, Gansu, and Chongqing. DNA sequencing showed that the Yunnan samples were also genetically distinct. γ-Humulene and a new bisabolane sesquiterpene were isolated.

Four New Sesquiterpenoids from Ligularia subspicata Collected in China; Isolation of a Bakkane-type Lactone, an Eremophilane-type Lactone, and Two Ortho Esters

A bakkane type lactone, an eremophilane type lactone, and two ortho esters were isolated from Ligularia subspicata collected in Sichuan Province, China. The ortho ester type compound has been isolated from Ligularia for the first time.

Constituents of Ligularia brassicoides Collected in China: A New Diels-Alder Adduct of Eremophilan-10βol and Methacrylic Acid

Chemical study of four samples of Ligularia brassicoides collected in Sichuan Province of China afforded 18 compounds, five of which were new. LC-MS profiles were somehow similar to each other, although the compound ratio was slightly different. One of the new compound was a Diels-Alder adduct between franoeremophilan-10β-ol and methacrylic acid.

Diversity in the Flavonoid Composition of Stellera chamaejasme in the Hengduan Mountains

The presence of diversity in the Stellera chamaejasme population was found via their chemical composition. The eight collected samples were grouped into two chemotypes on the basis of the amount of neochamaejasmin B and chamaejasmine. Diversity was also found in the amount of afzelechin. The stereochemistry of neochamaejasmin B was confirmed by NOE experiment.

Chemotypes of Ligularia vellerea, its Hybrids, and L. melanothyrsa

Ligularia vellerea and L. melanothyrsa have been found to share chemical characteristics based on geography. In one chemotype (Shangrila type), the major components were either 15-oxygenated furanoeremophilanes or eremophilanolides; and in another (Luguhu type), either 1-angeloyloxyfuranoeremophilanes or corresponding lactones. The two L. vellerea samples were found to have experienced hybridization with either L. cyathiceps or L. kanaitzensis; however, compounds typical of L. vellerea alone were isolated from them.

The First Isolation of Furanoeremophilane from Ligularia nelumbifolia

Ligularol (1), a furanoeremophilane, was isolated together with eremophil-1(10)-en-11-ol (2) from one of eight collected samples of Ligularia nelumbifolia and L. kongkalingensis, a closely related species. It is proposed that the ability to produce the furanoeremophilane has been acquired through hybridization.

Eight New Alkyne and Alkene Derivatives from Four Saussurea Species Collected in China

Five samples of four Saussurea species, S. hieracioides, S. stella, S. graminea, and S. tatsienensis, collected in Sichuan Province, China were studied and seven new diynes and a new alkene derivatives were isolated along with 16 known compounds. Absolute configurations of two of the new compounds were established using a modified Mosher's method.

Chemical Constituents of Ligularia Nelumbifolia and L. Subspicata Hybrid Collected in Shangrila County, Yunnan Province of China

Four Ligularia individuals possessing morphological characters of both L. nelumbifolia and L. subspicata were discovered in Shangrila County, Yunnan Province, China. DNA sequencing showed that the specimens were hybrids of the two species and their maternal parent was L. subspicata. The chemical composition of the root extract was examined for three of them as well as L. nelumbifolia and L. subspicata collected sympatrically. Nelumol was isolated from L. nelumbifolia, and furanoeremophilanes from L. subspicata. While nelumol and furanoeremophilanes were detected in two of the hybrid samples, only furanoeremophilanes were detected in the others.

Four New Guaianolides and Acetylenic Alcohol from Saussurea Katochaete Collected in China

Four new guaianolides and an acetylenic alcohol were isolated from Saussurea katochaete (Asteraceae) collected in China. The structures were determined based on the spectroscopic data including the absolute configuration by application of advanced Mosher's method.

Complex Diversity in

Two samples of Ligularia kanaitzensis collected in the Shizhongshan Mountain region of Yunnan Province, as well as one sample collected in Sichuan Province, were analyzed with regard to root constituents and neutral DNA sequences. The two Shizhongshan samples were found to be different from each other and from other samples analyzed previously, indicating that the intra-specific diversity in the species was highly complex.

Four New Eremophilane-Type Alcohols from Collected in China

Four new eremophilane-type sesquiterpenoid alcohols were isolated from Cremanthodium helianthus collected in China and their structures established on the basis of spectroscopic analyses. All of them had 9-en-8-one partial structures with one more double bond either Δ11, Δ11(13), or Δ7(11). Two of them had a hydroxy group at C-1 position.