Sesquiterpenes fromLigularia Fischeri

Anti-inflammatory sesquiterpenoids from Ligularia fischeriTurcz

Ligularia fischeriTurcz. is a medicinal plant for the treatment of inflammation in China and Korea. Its chemical components in anti-sepsis activity and the related molecular mechanisms remain unknown yet. In this study, two undescribed eremophilane sesquiterpenoids fischerins A (1) and B (2), together with 8 known sesquiterpenoid derivatives (3-10), were isolated from the whole plant of L. fischeri. Their structures were identified by detailed spectroscopic and ECD analyses. 3-Oxo-8-hydroxyeremophila-1,7(11)-dien-12,8-olide (6) showed the most inhibitory effect on NO production in LPS-stimulated RAW 264.7 cells with the IC50 value of 6.528 μM. Meanwhile, compound 6 also decreased the mRNA expression of pro-inflammatory factors IFN-γ, IL-1β, IL-6 and TNF-α via downregulating NF-κB signaling pathway in vitro. Furthermore, compound 6 reduced the mortality, murine sepsis score, the serum TNF-α level and organic damage in a mouse model of sepsis. These findings indicated that compound 6 possessed the potent anti-inflammatory activity and had the potential as a promising drug candidate for sepsis therapy.

Three undescribed compounds from Diaporthe biguttusis T-24, an endophytic fungus isolated from Ligularia fischeri

Diaporthpyran A (1), diaporthester E (2) and diaporthester F (3), three new compounds along with four known compounds (4-7) were isolated from the crude extract of Diaporthe biguttusis T-24, an endophytic fungus isolated from Ligularia fischeri. The planar structures of compounds 1-3 including the relative and absolute configurations were elucidated on the basis of HRMS, NMR, J-based coupling constant analysis, CD, and calculated ECD analysis. In addition, compounds 1 and 3 were evaluated for their cytotoxic activities against four human cancer cell lines.

New eremophilane-type sesquiterpenes from Synotis solidaginea

Eleven new highly oxygenated eremophilane-type sesquiterpenoids were isolated from the whole plant of Synotis solidaginea, including two pairs of C-8 S/R epimers. The structures of the new compounds were elucidated on the basis of detailed spectroscopic analysis and the absolute configurations of 1 and 9 were confirmed by single-crystal X-ray crystallography using Cu Kα radiation. All the isolates were tested for the inhibition of LPS-stimulated NO production in macrophage-like mouse monocytic leukemia RAW264.7 cells. Compound 1 exhibited weak inhibitory effects with an IC50 of 71.2 μM.

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.

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.

Phytochemical study of Ligularia subspicata and valuation of its anti-inflammatory activity

This report illustrated isolation and identification of 42 compounds comprising five (spicatainoids A-E) undescribed eremophilanolide type sesquiterpenoids and one undescribed nor-eremophilane (spicatainoid F) from Ligularia subspicata.. Among all the isolated new compounds, 4 is reported as the first enantiomeric form of novel eremophilanolide type sesquiterpenoid. Comprehensive analysis of HRESIMS, 1D/2D NMR, experimental circular dichroism (CD), calculated ECD analysis, and X-ray crystallographic (XRD) analysis validated the complete configuration and confirmation of these isolated compounds. All the isolated compounds were tested for the anti-inflammatory potential by measuring the amount of nitric oxide production. Among the tested compounds, 4 was the most effective with 90% NO-inhibition activity. Compounds 1, 2, 3, 9, 10 18, 29, 34, 35 exhibited moderate inhibitory effects against the production of NO, while other compounds displayed no activity even at the concentration of 50 μM. Additionally, compounds 1, 3 and 4 presented moderate anti-inflammatory activity by inhibiting the release of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) in LPS-stimulated N9 cells. The IC₅₀ values of compounds 1, 3 and 4 were calculated 39.6 ± 2.7, 42.5 ± 3.8 and 27.60 ± 1.9 μΜ.

Identification of the Sesquiterpene Cyclase Involved in the Biosynthesis of (+)-4-Epi-eremophil-9-en-11-ol Derivatives Isolated from Botrytis cinerea

Cultivation of the phytopathogenic fungus Botrytis cinerea using sublethal amounts of copper sulfate yielded a cryptic sesquiterpenoids family, which displayed the basic chemical structure of (+)-4-epi-eremophil-9-ene. The biosynthesis pathway was established, and the route involved the likely transformation of the diphosphate of farnesyl (FDP), to give a cis-fused eudesmane cation, through (S)-hedycaryol, finally yielding the (+)-4-epi-eremophil-9-enol derivatives. An expression study of genes that code for the sesquiterpene cyclases (STC), including the recently reported gene Bcstc7 present in the B. cinerea genome, was performed in order to establish the STC involved in this biosynthesis. The results showed a higher expression level for the Bcstc7 gene with respect to the other stc1-5 genes in both wild-type strains, B05.10 and Botrytis cinerea UCA992. Deletion of the Bcstc7 gene eliminated (+)-4-epi-eremophilenol biosynthesis, which could be re-established by complementing the null mutant with the Bcstc7 gene. Chemical analysis suggested that STC7 is the principal enzyme responsible for the key step of cyclization of FDP to eremophil-9-en-11-ols. Furthermore, a thorough study of the two wild-types and the complemented mutant revealed four new eremophilenol derivatives whose structures are reported here.

Isolation, Structure Elucidition, and Immunosuppressive Activity of Diterpenoids from Ligularia fischeri

Six new (1-3 and 6-8) and seven known diterpenoids were isolated from the whole plant of Ligularia fischeri. Compound 1 is a new 15,16-dinorerythroxylane-type diterpenoid possessing a C₁₈ skeleton, and 2 is the first example of a 6/6/6/6/5/5-fused hexacyclic ent-kaurane diterpenoid with 19,20-olide and 11,16-epoxy moieties. The structures of the new compounds were elucidated by spectroscopic analysis and chemical methods. The absolute configurations of 1 and 7 were determined by single-crystal X-ray diffraction. Compounds 1-13 were evaluated for their immunosuppressive activity, and 4, 7, and 13 showed moderate inhibitory activities against human B lymphoblast HMy2.CIR cells with IC₅₀ values of 56.3 ± 2.2, 13.3 ± 0.8, and 31.4 ± 0.9 μM, respectively.

4,5-Di-O-Caffeoylquinic Acid from Ligularia fischeri Suppresses Inflammatory Responses Through TRPV1 Activation

Ligularia fischeri (Ledeb.) Turcz., a perennial plant native to northeastern Asia, has long been used as folk remedies for the alleviation of inflammatory symptoms. We investigated whether the extract of L. fischeri (LFEx) and caffeoylquinic acid (CQA) derivatives, the pharmacologically active ingredients identified from L. fischeri, regulate inflammation via a transient receptor potential vanilloid 1 (TRPV1)-mediated pathway. Changes in intracellular Ca²⁺ levels to the LFEx and trans-5-O-CQA, 3,4-di-O-CQA, 3,5-di-O-CQA, and 4,5-di-O-CQA were monitored in TRPV1-expressing human embryonic kidney cell HEK 293T. LFEx and 4,5-di-O-CQA (EC₅₀  = 69.34 ± 1.12 μM) activated TRPV1, and these activations were significantly inhibited by ruthenium red, a general blocker of TRP channels, and capsazepine, a specific antagonist of TRPV1. 4,5-Di-O-CQA has been determined having antiinflammatory effect under hypoxic conditions by detecting the expression of cyclooxygenase-2 (COX-2), a representative inflammatory marker, and cellular migration in human pulmonary epithelial A549 cells. 4,5-Di-O-CQA suppressed COX-2 expression and cell migration, and this inhibition was countered by co-treatment with capsazepine. This study provides evidence that L. fischeri is selective to inflammatory responses via a TRPV1-mediated pathway, and 4,5-di-O-CQA might play a key role to create these effects. Copyright © 2017 John Wiley & Sons, Ltd.

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.

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.

A New Eudesmane Sesquiterpene from Dichrocephala integrifolia

A new sesquiterpene, eudesm-11-ene-4α,7β,9β-triol, was isolated from the EtOH extract of aerial parts of Dichrocephala integrifolia. Its structure was determined on the basis of spectral analysis of 1D and 2D NMR data.

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.

A pair of epimeric spirosesquiterpenes from the roots of Ligularia fischeri

Two new highly oxygenated spirosesquiterpene lactones, ligulactones A (1) and B (2), and one known sesquiterpenoid, 1beta,10beta-epoxy-6beta-isobutyryloxy-9-oxo-furanoeremophilane (3), were isolated from the roots of Ligularia fischeri. Their structures and relative configurations were elucidated by 1D and 2D NMR and MS data and by comparison of their NMR data with those of related compounds. Single-crystal X-ray diffraction analyses confirmed their structures. Compounds 1 and 2 are C-7 epimers. A possible biosynthetic process for their formation is proposed. Structure 3 was proposed as the likely parent compound for the two new epimeric sesquiterpenoids.