Five new subspicatins and noreremophilane from Parasenecio petasitoides collected in China

Isomeric eremophilane lactones from the whole plant of Parasenecio albus and their cytotoxic and immunosuppressive activities

Ten previously unreported eremophilane lactones (parasalbolides A-J), including three pairs of C-10 epimers (parasalbolides A and G, B and H, and F and I, respectively), were isolated and identified from the whole plant of Parasenecio albus. Their structures were established on the basis of the HRESIMS and NMR spectroscopic analyses, combined with the comparison of the ECD spectra. The absolute configuration of parasalbolide A was confirmed by single-crystal X-ray diffraction using Cu Kα radiation. Parasalbolides A-J represent the first examples of 1,2,10-trioxygenated eremophila-7(11),8-dien-12,8-olides. The cytotoxic and immunosuppressive activities of selected isolates were evaluated and the (10S)-eremophilane lactones (parasalbolides A, B, and F) showed more potent activities than the (10R)-ones (parasalbolides G, H, and I).

Chemical and Genetic Diversity of Ligularia kanaitzensis in the Hengduan Mountains Area. Chemical Relationship with L. subspicata

Root chemicals and the sequences of the internal transcribed spacers (ITSs) were analyzed for 9 Ligularia kanaitzensis and 3 L. subspicata samples collected in northwestern Yunnan and southwestern Sichuan, China. Subspicatins A and C were isolated from two L. kanaitzensis samples. Introgression of genes responsible for these compounds from L. subspicata was suggested by their strong connection with L. subspicata/L. lamarum and the geographical proximity of the samples to L. subspicata. DNA analysis of a set of 27 L. kanaitzensis samples including those analyzed previously showed that they belong to two clades, designated A and B. Together with the presence/absence of furanoeremophilane, the 27 samples were sorted into three groups: clade A/furan, clade B/furan, and clade B/non-furan. The ancestral plant presumably belonged to clade B/non-furan, because furanoeremophilanes are biosynthesized from eremophilan-8-ones. 1β-Angeloyloxyfukinone, a likely intermediate between fukinone and subspicatin C, was isolated for the first time. This finding allowed us to propose plausible biosynthetic pathways of subspicatins A and C.

Eremophilane sesquiterpenoids from the whole plant of Parasenecio albus with immunosuppressive activity

Fifteen new highly oxygenated eremophilane sesquiterpenoids, parasubolides A-O (1-15), were obtained from the whole plant of Parasenecio albus. The structures of 1-15 were elucidated based on the interpretation of NMR and HRESIMS data, along with experimental electronic circular dichroism (ECD) and single-crystal X-ray diffraction analysis. Compounds 1-6, and 9-14 represent the first class of 1,2,10-trioxygenated eremophilane lactones. Selected isolates were evaluated for their immunosuppressive activities. Compounds 4, 5, and 12 exhibited moderate inhibition against LPS-induced B-cell proliferation with IC₅₀ values of 23.1, 33.8, and 26.6 μM, respectively.

Chemical constituents of hybrids of Ligularia cyathiceps and L. lamarum/L. subspicata collected in China: Structures of subspicatins M, N, O1, and O2, and related compounds

Three natural hybrids and an introgressed individual of Ligularia were evaluated based on a combination of morphology, root chemicals, and nucleotide sequences of evolutionally neutral regions to understand the chemical outcomes of hybridization and introgression. Six previously undescribed eremophilane sesquiterpenes were isolated from hybrids between L. cyathiceps and L. lamarum/L. subspicata, and benzofurans were isolated from L. subspicata for the first time. Their structures were elucidated based on spectroscopic analyses. Some compounds produced by hybrids have not been detected in either parental species, indicating that the metabolic profile was altered by hybridization and introgression.

Sesquiterpenoids and monoterpenoid coumarins from Parasenecio rubescens

Ten new sesquiterpenoids (1–2, 5–9, 12–14) and four new monoterpenoid coumarins (15–18) were isolated from the whole plant of Parasenecio rubescens.

[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.

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.

Eremophilane-Type Sesquiterpenoids from an Acremonium sp. Fungus Isolated from Deep-Sea Sediments

Chemical examination of an EtOAc extract of a cultured Acremonium sp. fungus from deep-sea sediments resulted in the isolation of 15 new eremophilane-type sesquiterpenoids, namely, acremeremophilanes A-O (1-15), together with seven known analogues. The structures of new compounds were determined through extensive spectroscopic analyses, in association with chemical conversions and ECD calculations for configurational assignments. The PKS-derived 4-hexenoic acid unit in 2-6 is rarely found in nature. All compounds were evaluated for inhibitory effects toward nitric oxide production induced by lipopolysaccharide in RAW 264.7 macrophage cells. Compounds 2-6 and 14 exhibited inhibitory effects with IC50 values ranging from 8 to 45 μM.

Chemical and genetic diversity of Cremanthodium lineare

Chemical constituents and evolutionally neutral DNA sequences of six samples of Cremanthodium lineare Maxim., collected in the Sichuan Province of China, were studied. Three samples produced furanoeremophilanes and the other three, eremophilan-8-ones. The chemotypes were found to be correlated with DNA sequence types, suggesting that the chemical diversity observed has a genetic origin. Production of furanoeremophilanes by a Cremanthodium species suggests an evolutionary relationship between Cremanthodium and Ligularia species, and possibly to related genera.

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.

Four eremophil-9-en-8-one derivatives from Cremanthodium stenactinium samples collected in China

Two samples of Cremanthodium stenactinium (Asteraceae) were collected in Sichuan Province, China. From the ethyl acetate extracts of the roots, three new eremophilane-type sesquiterpenoids and one new trinoreremophilane compound were isolated, together with other known eremophilanes. Their structures were determined based on the spectroscopic data. This is the first report of isolation of eremophilane-type compounds from the genus Cremanthodium.