High diversity of Ligularia dictyoneura in chemical composition and DNA sequence

Chemical Constituents of Ligularia Species (Asteraceae) and Their Diversity in East Asia

More than 100 Ligularia species and those of several related genera (Cremanthodium, Cacalia, Senecio, and others) in the plant family Senecioneae grow in East Asia. For many years, researchers have studied the chemical constituents of these plants, and terpenoids, flavonoids, sterols, alkaloids, and aromatic compounds have been isolated. Among these, in particular, numerous sesquiterpenoids were reported. In this contribution, relevant chemical studies are described mainly from literature reports appearing since 2000, inclusive of investigations performed by the present authors, on the diversity in secondary metabolites of Ligularia growing in the Hengduan Mountains area of China, focusing on eremophilane sesquiterpenoids and other metabolites. Terpenoids and aromatic compounds (totaling 1049), both new and known, are listed. Genetic studies and synthesis investigations are also reviewed briefly.

Diversity in Eremophilane Components of Ligularia dictyoneura in Yunnan and Sichuan Provinces of China

The chemical composition of 3 samples of Ligularia dictyoneura was studied. Nine furanoeremophilanes 1 to 9 and bakkenolide A (10) were isolated, among which compound 6 was a new furanoeremophilane-15,6-olide. These results, together with our previous results on 20 L. dictyoneura samples, show that furanoeremophilane is the major compound in the peripheries of the plant’s distribution area, while eremophilan-8-one, in the center. DNA analysis suggests that a furanoeremophilane producer in the center, an exception, is introgressed; namely, the ability to produce furanoeremophilane in the sample may have its origin in some other plant.

Two new eremophilane Sesquiterpenoides from Ligularia dictyoneura

Two new eremophilane sesquiterpenoides, 6α,9α-dihydroxyeremophilenolide (1), and 1β,10β-dihydroxyeremophilenolide (2), along with ten known eremophilane sesquiterpenoides (3-12) were isolated from the aerial parts of Ligularia dictyoneura (Franch.) Hand.-Mazz. Their structures were elucidated by means of extensive spectroscopic analysis. Compounds 3-6 were assessed for their cytotoxicity against five human cancer cell lines (HL-60, SMMC-7721, A-549, MCF-7 and SW-480), and the result showed that they had no activity.

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.

[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.

Chemical and genetic similarity and diversity of Ligularia anoleuca and L. fischeri collected in the Hengduan Mountains of China

The sesquiterpenoid composition in the root and the DNA sequences of evolutionarily neutral regions were studied in Ligularia anoleuca and Ligularia fischeri (Asteraceae) collected in the Sichuan Province of China. LC-MS analysis showed that L. anoleuca populations from different localities had different chemical compositions. However, the isolated compounds were similar to each other, indicating that the differences in chemical composition were not large. The DNA analysis suggested that the two species were indistinguishable. Seventeen furanoeremophilanes and an eremophilane acetal were isolated.

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.

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.

Chemical and genetic study of Ligularia duciformis and related species in Sichuan and Yunnan Provinces of China

The chemical constituents of the root extracts and the evolutionarily neutral DNA base sequences were studied for 28 samples of Ligularia duciformis, L. kongkalingensis, and L. nelumbifolia collected in Sichuan and Yunnan Provinces of China. The samples could be classified into four chemotypes (1-4). Sesquiterpenoids having eremophilane and oplopane skeletons were isolated from two (Chemotype 1) and three (Chemotype 2) samples, respectively. Two new oplopane derivatives were isolated and their structures were determined. In 18 samples, phenylpropenoids were the major components (Chemotype 3). In five samples, neither phenylpropenoids nor sesquiterpenoids were found (Chemotype 4). Despite this large chemical variety, no correlation was found between the chemotype and the morphological criteria of species identification. The analysis of the evolutionarily neutral DNA regions also indicated that the samples were not separated into distinct clades and that introgression was extensive.

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.

Diversity of Furanoeremophilanes in Major Ligularia Species in the Hengduan Mountains

The chemical and genetic diversity of Ligularia species in the Hengduan Mountains area of China is reviewed. A hypothesis that the production of furanoeremophilanes is ecologically advantageous is proposed.

Phytochemicals and biological activities of Ligularia species

Ligularia, an important genus of the Compositae family, has captured the interest of natural product chemists for years. Phytochemical investigations on the title genus have led to isolation of hundreds of secondary metabolites with various skeletons. Herein, we summarized the chemical constituents of this genus and their biological activities over the past few decades.

Chemical and genetic differentiation of Ligularia hodgsonii in Japan and China

The chemical composition of the root extract and neutral base sequences of L. hodgsonii samples collected in Japan and China were examined. From the Japanese and the Chinese samples, 6beta-(angeloyloxy)furanoeremophilan-15-oic acid and 3beta-acetoxy-6beta-[(2-methylbutanoyl)oxy]furanoeremophilan-10beta-ol were isolated as the major component, respectively. The sequence of the internal transcribed spacers (ITSs) of the ribosomal RNA gene was different in the Japanese and the Chinese samples. In contrast to the significant genetic difference, chemical diversity was limited to the positions of O-functionalities on the furanoeremophilane skeleton, supporting our hypothesis that the production of furanoeremophilanes is ecologically advantageous.

Two New Furanoeremophilane Sesquiterpenoids from: Ligularia oligonema

From the roots of Ligularia oligonema and an unidentified sample of Ligularia collected in Yunnan Province of China, two new sesquiterpenoids, 3β-acetoxy-6β-(2-methylbutyryloxy)furanoeremophilan-10β-ol and 3β-acetoxy-6β-isobutyryloxy-furanoeremophilan-10β-ol, were isolated. DNA sequencing showed that the unidentified sample was likely to be L. oligonema. In addition, the DNA data suggested that the chemical evolution among L. oligonema and related Ligularia species is rather complex.

Chemical constituents and diversity of Ligularia lankongensis in Yunnan Province of China

The chemical constituents of the roots of Ligularia lankongensis collected at seven different places in Yunnan Province, China, were investigated together with the DNA sequence of the atpB- rbcL intergenic region. All the samples contained a new, highly oxygenated bisabolane-type sesquiterpene ( 1). Four other oxygenated bisabolanes ( 2 and the new 3, 4, and 5) were also obtained. Intraspecific diversity was observed in the composition of the compounds, but not in the DNA sequence.