Sesquiterpene Lactones Containing an α-Methylene-γ-Lactone Moiety Selectively Down-Regulate the Expression of Tumor Necrosis Factor Receptor 1 by Promoting Its Ectodomain Shedding in Human Lung Adenocarcinoma A549 Cells.

Alantolactone is a eudesmane-type sesquiterpene lactone containing an α-methylene-γ-lactone moiety. Previous studies showed that alantolactone inhibits the nuclear factor κB (NF-κB) signaling pathway by targeting the inhibitor of NF-κB (IκB) kinase. However, in the present study, we demonstrated that alantolactone selectively down-regulated the expression of tumor necrosis factor (TNF) receptor 1 (TNF-R1) in human lung adenocarcinoma A549 cells. Alantolactone did not affect the expression of three adaptor proteins recruited to TNF-R1. The down-regulation of TNF-R1 expression by alantolactone was suppressed by an inhibitor of TNF-α-converting enzyme. Alantolactone increased the soluble forms of TNF-R1 that were released into the culture medium as an ectodomain. The structure-activity relationship of eight eudesmane derivatives revealed that an α-methylene-γ-lactone moiety was needed to promote TNF-R1 ectodomain shedding. In addition, parthenolide and costunolide, two sesquiterpene lactones with an α-methylene-γ-lactone moiety, increased the amount of soluble TNF-R1. Therefore, the present results demonstrate that sesquiterpene lactones with an α-methylene-γ-lactone moiety can down-regulate the expression of TNF-R1 by promoting its ectodomain shedding in A549 cells.

Insecticidal, antifeedant and acetylcholinesterase inhibitory activity of sesquiterpenoids derived from eudesmane, their molecular docking and QSAR.

This work evaluated the insecticidal, antifeedant and AChE inhibitory activity of compounds with eudesmane skeleton. The insecticidal activity was tested against larvae of Drosophila melanogaster and Cydia pomonella, the compounds 3 and 4 were the most active (LC50 of 104.2 and 106.7 µM; 82.0 and 84.4 µM, respectively). Likewise, the mentioned compounds were those that showed the highest acetylcholinesterase inhibitory activity, with IC50 of 0.26 ± 0.016 and 0.77 ± 0.016 µM, respectively. Enzyme kinetic studies, as well as molecular docking, show that the compounds would be non-competitive inhibitors of the enzyme. The antifeedant activity on Plodia interpunctella larvae showed an antifeedant index (AI) of 99% at 72 h for compounds 16, 27 and 20. The QSAR studies show that the properties associated with the polarity of the compounds would be responsible for the biological activities found.

Alantolactone derivatives inhibit the tumor necrosis factor α-induced nuclear factor κB pathway by a different mechanism from alantolactone.

Alantolactone is a eudesmane-type sesquiterpene lactone that exerts various biological effects, including anti-inflammatory activity. In the present study, screening using the RIKEN Natural Products Depository chemical library identified alantolactone derivatives that inhibited the expression of intercellular adhesion molecule-1 (ICAM-1) on human umbilical vein endothelial cells stimulated with proinflammatory cytokines and Toll-like receptor ligands. In human lung adenocarcinoma A549 cells stimulated with tumor necrosis factor-α (TNF-α), six alantolactone derivatives inhibited ICAM-1 expression in a dose-dependent manner and at IC50 values of 13-21 µM, whereas that of alantolactone was 5 µM. Alantolactone possesses an α-methylene-γ-lactone moiety, whereas alantolactone derivatives do not. In the nuclear factor κB (NF-κB) signaling pathway, alantolactone prevented the TNF-α-induced phosphorylation and degradation of the inhibitor of NF-κB α (IκBα) protein, and its downstream signaling pathway. In contrast, alantolactone derivatives neither reduced TNF-α-induced IκBα degradation nor the nuclear translocation of the NF-κB subunit RelA, but inhibited the binding of RelA to the ICAM-1 promoter. The inhibitory activities of alantolactone and alantolactone derivatives were attenuated by glutathione. These results indicate that alantolactone derivatives inhibit the TNF-α-induced NF-κB pathway by a different mechanism from alantolactone.

Eudesmane sesquiterpenoids with inhibitory effects on NO production from Artemisia princeps.

Five undescribed eudesmane methyl esters (1-5), three undescribed eudesmane-12,6-olides (6-8), and 21 known analogues (9-29) were isolated from the aerial part of Artemisia princeps Pamp. Their structures were established by detailed analysis of the NMR and HRESIMS data. The absolute configurations of 1-8 were determined based on single-crystal X-ray diffraction analysis and ECD calculations. Moreover, the inhibitory effects on LPS-induced NO production in BV-2 microglial cells of all the isolated compounds were assessed. Except for compounds 2, 4, 10, and 11, the others showed significant inhibitory activities, with IC50 values of 0.73-18.66 µM, wherein the potential structure-activity relationship was also discussed.

Eudesmane-type sesquiterpenoids from the aerial parts of Artemisia lavandulaefolia and their anti-pancreatic cancer activities.

Five undescribed eudesmane sesquiterpenoids, artemilavanins A-E, and one undescribed rearranged eudesmane sesquiterpenoid, artemilavanin F, were isolated from the 95% ethanol extract of the aerial parts of Artemisia lavandulaefolia DC., along with ten known compounds. The structures and configurations of undescribed compounds were mainly elucidated by spectroscopic analyses and single-crystal X-ray diffraction analysis. Among all isolated compounds, artemilavanin F exhibited inhibitory activity on PANC-1 pancreatic cancer cells with IC50 of 9.69 ± 2.39 µM. Artemilavanin F inhibited PANC-1 cell proliferation by induction of G2/M cell cycle arrest and apoptosis mediated by downregulation of cyclin-dependent kinases and accumulation of reactive oxygen species. Moreover, artemilavanin F inhibited the colony formation, cell migration and sphere formation of PANC-1 cells, indicating the suppression of stem-cell-like phenotype of PANC-1 cells. Further results confirmed that the expression of cancer stem cell markers such as Bmi1, CD44, CD133 were inhibited by artemilavanin F. Downregulation of epithelial-mesenchymal transition (EMT) markers such as N-cadherin and Oct-4 indicated the potential of artemilavanin F in prevention of metastasis.

Eudesmane sesquiterpenoid glycosides from the leaves of Pittosporum lenticellatum with anti-neuroinflammatory activity.

Chemical investigation of the EtOAc extract of the leaves of Pittosporum lenticellatum led to the isolation of twenty-five previously undescribed eudesmane sesquiterpenoid glycosides, pitlencosides A－Y (1-25); their structures were elucidated by extensive spectroscopic analysis, including 1D and 2D NMR, HR-ESI-MS, ECD spectra, and X-ray crystallographic analysis. Among them, compounds 4, 5, 7, 8, 15 and 16 exhibited significant inhibitory effects on the production of nitric oxide in lipopolysaccharide-induced BV-2 microglial cells by suppressing the expression of inducible nitric oxide synthase and cyclooxygenase-2, with IC50 values ranging from 7.95 to 25.88 µM, which showed stereo-chemical and substituent dependents. Western blot analysis and molecular docking simulation confirmed the anti-inflammatory activity of compounds 4, 5, 7, 8, 15 and 16.

Ent-eudesmane sesquiterpenoids from the Chinese liverwort Chiloscyphus polyanthus.

- Seven previously undescribed ent-eudesmane sesquiterpenoids (1-7), as well as seven known analogs (8-14), were isolated from the Chinese liverwort Chiloscyphus polyanthus var. rivularis. Their structures were established based on comprehensive spectroscopy analysis, electronic circular dichroism calculations, as well as biosynthetic considerations. The cytotoxicity against HepG2 (Human hepatocellular carcinomas) cancer cell line, and antifungal activity against Candida albicans SC5314 of all isolated ent-eudesmane sesquiterpenoids were preliminarily tested, results showed that the tested compounds did not display obvious cytotoxicity and antifungal activities under the tested concentration.

Two New Eudesmane-Type Sesquiterpene from Clonostachys sp. Y6-1and Their Cytotoxic Activity.

Two undescribed eudesmane-type sesquiterpenoids together with four known compounds were isolated from Clonostachys sp. Y6-1 associated. Their chemical structures were unambiguously determined by NMR, mass spectrometry, and 13 C-NMR calculation as well as DP4+ probability analyses. The absolute configurations of compounds 1 and 2 were determined by ECD calculation and X-ray single-crystal diffraction methods. Furthermore, all isolates were evaluated for in vitro cytotoxic activities against MCF-7, HCT-116, MDA-MB-231, and SW620 cancer cells. Among them, bioactivity evaluation of compound 5 revealed that weak activity (IC50 =66.55±0.82 µM) against SW620.

Four new eudesmane-type and one new eremophilane-type sesquiterpenes from the whole plant of Carpesium abrotanoides L.

The extract of the whole plant of Carpesium abrotanoides L. yielded five new sesquiterpenes including four eudesmanes (1-4) and one eremophilane (5). The new compounds were characterized by spectroscopic analysis especially 1D and 2D NMR spectroscopy and HRESIMS data. Structurally, both compounds 1 and 2 were sesquiterpene epoxides and 2 owned an epoxy group at C-4/C-15 position to form a spiro skeleton. Compounds 4 and 5 were two sesquiterpenes without lactones and 5 possessed a carboxy group in the molecule. Additionally, all the isolated compounds were preliminarily evaluated for the inhibitory activity against SARS-CoV-2 main protease. As a result, compound 2 showed moderate activity with an IC50 value of 18.79 µM, while other compounds were devoid of noticeable activity (IC50 > 50 µM).

Pitsubcosides A-L, highly esterified eudesmane sesquiterpenoid glycosides with antibacterial activity from Pittosporum subulisepalum and their mechanism.

BACKGROUND: Plants from the genus Pittosporum are traditionally used as antibacterial, antifungal and antiviral agents. A bioassay evaluation of the extract of Pittosporum subulisepalum revealed antibacterial activity. This study focused on the discovery of the antibacterial metabolism in P. subulisepalum, as well as the modes of action of its active components. RESULTS: A chemical investigation of an ethyl acetate (EtOAc) extract of the aerial parts of P. subulisepalum led to the isolation of 12 previously undescribed eudesmane sesquiterpenoid glycoside esters (ESGEs), pitsubcosides A-L (1-12). Their structures were elucidated by extensive spectroscopic analysis, including one- and two-dimensional NMR, high-resolution electrospray ionization mass spectrometry, electronic circular dichroism spectra and single-crystal X-ray crystallography analysis or by comparing with authentic samples. The new ESGEs were characterized by their highly esterified glycoside moieties. Among them, compounds 1-3, 5 and 8 showed a moderate inhibitory effect against Staphylococcus aureus, methicillin-resistant S. aureus (MRSA), Bacillus cereus, Bacillus subtilis, Pseudomonas syringae pv. actinidiae (Psa) and Erwinia carotovora with minimum inhibitory concentrations (MICs) ranging from 3.13 to 100 µm. Among them, compounds 3 and 5 showed remarkable antibacterial activity against S. aureus and Psa with MIC values of 6.25 and 3.13 µm, respectively. Live bacterial mass and the biofilms of S. aureus and Psa were quantified using methyl tetrazolium and crystal violet assays. Fluorescence microscopy and scanning electron microscopy experiments revealed an antibacterial mechanism of cell membrane architectural disruption. CONCLUSION: The results suggest that ESGEs possess great potential for the development of antibacterial agents to control plant pathogens. © 2023 Society of Chemical Industry.

Modulatory Effects of Atractylodin and ß-Eudesmol on Human Cytochrome P450 Enzymes: Potential Drug-Drug Interactions.

Atractylodin and ß-eudesmol, the major bioactive compounds in Atractylodes lancea, are promising candidates for anti-cholangiocarcinoma. The inhibitory effects of both compounds on human rCYP1A2, rCYP2C9, rCYP2C19, rCYP2D6 and rCYP3A4 enzymes were investigated using luminogenic CYP450 kits. The modulatory effects were investigated in mouse livers following a daily oral dose of atractylodin or ß-eudesmol at 100 mg/kg body weight for 1, 7, 14, and 21 days. The inhibitory effects of both compounds on all rCYP450s were weak (IC50: 167 to >686 µM). ß-Eudesmol showed the most potent inhibitory effect on rCYP2C19 (IC50 = 172.7 µM) and rCYP3A4 (IC50 = 218.6 µM). Results of the ex vivo study showed that short exposure (1-7 days) of atractylodin and ß-eudesmol resulted in the upregulation of mRNA. Prolonged exposure to the daily oral dose for at least 14 days significantly downregulated the expressions of mRNA and proteins, which correlated with the decrease in the activities of mCYP1A2 and mCYP3A11. Based on the results of the ex vivo study, clinical uses of atractylodin or ß-eudesmol for the treatment of cholangiocarcinoma are of concern for the risk of toxicity due to hCYP3A4 inhibition following chronic dosing, as well as the metabolic interaction with the coadministered drugs that are metabolized by hCYP3A4.

Structurally diverse new eudesmane sesquiterpenoids with anti-inflammatory activity from the fruits of Alpinia oxyphylla.

The phytochemical investigation of the fruits of Alpinia oxyphylla led to the isolation and identification of 40 structurally diverse sesquiterpenoids, including 17 new eudesmane sesquiterpenoids (1-17) and 23 known analogues (18-40). Among the isolates, 14 and 17 were unusual rearranged eudesmane sesquiterpenoids, featuring rare 5/6-fused and 6/8-fused bicyclic carbon skeleton, respectively; 15 and 16 were the novel 6,7-seco-eudesmane sesquiterpenoids isolated from plant-origin for the first time, 1 and 3-6 were rare nor-eudesmane sesquiterpenoids. Their structures were elucidated by comprehensive spectroscopic data analysis (NMR, HRESIMS, IR, UV), single crystal X-ray diffraction, and quantum chemistry calculations (ECD and 13C NMR). Moreover, all isolates were evaluated by measuring their inhibitory effect on nitric oxide (NO) in LPS-stimulated BV-2 cells. As a result, compounds 11, 20, 24 and 40 showed moderate to strong inhibition on NO productions, with IC50 values ranging from 21.63 to 60.70 µM. Meanwhile, these compounds also partially decreased the secretion of TNF-α and IL-6 in LPS-stimulated BV-2 cells. Furthermore, 20 could down-regulate protein expressions (COX-2 and iNOS) and observably inhibit the mRNA expressions of TNF-α, IL-6, COX-2 and iNOS. In this study, the discovery of structurally diverse anti-inflammatory sesquiterpenoids from the fruits of A. oxyphylla could benefit the further development and utilization of this plant.

Alantolactone inhibits oesophageal adenocarcinoma cells through nuclear factor erythroid 2-related factor 2-mediated reactive oxygen species increment.

BACKGROUND: Oesophageal adenocarcinoma (EAC) is a highly lethal cancer associated with a rapidly rising incidence and a poor prognosis. Alantolactone, a sesquiterpene lactone isolated from inula helenium, has anti-inflammatory, antimicrobial, neuroprotective activities, and anticancer properties. OBJECTIVE: In the present study, the anticancer effects of alantolactone on the human EAC cells were investigated in vitro and in vivo. METHODS AND FINDINGS: After treated with alantolactone, the cell viability of KYAE-1, KYAE-2, OE19, and OE33 cells reduced significantly compared with that of the control cells. Alantolactone induced apoptosis of the EAC cell lines by inhibiting the protein expression levels of nuclear factor erythroid2-related factor 2 (Nrf2). Furthermore, the apoptosis-inducing effect of alantolactone was enhanced by Nrf2 knockdown while reduced by overexpression of Nrf2. Antioxidant α-tocopherol and glutathione can protect EAC cell lines against alantolactone. A xenograft nude mice model showed that alantolactone can inhibit EAC growth in vivo. CONCLUSIONS: Alantolactone inhibits oesophageal adenocarcinoma cells through Nrf2-mediated reactive oxygen species (ROS) increment. Alantolactone maybe a potential therapeutical candidate for treating EAC.

Artemleucolides A-L, eudesmane-type sesquiterpenoids from Artemisia leucophylla and their antihepatoma cytotoxicity.

Twelve undescribed and 13 known eudesmane-type sesquiterpenoids were obtained from Artemisia leucophylla, and structurally elucidated based on comprehensive analyses of spectral data, including HRESIMS, IR, 1D and 2D NMR, and ECD calculation. The absolute configuration of compound 1 was determined by a single X-ray single crystal diffraction. Chemically, compounds 1-5 featured unprecedented 1,2-seco-1-nor-eudesmane-type skeleton with a cis-fused 6/5 bicyclic system. Antihepatoma evaluation against three human hepatoma cell lines (HepG2, Huh7, and SK-Hep-1) for all compounds demonstrated that compound 7 displayed the most active cytotoxicity with IC50 values of 35.1, 35.0, and 32.7 µΜ.

Eudesmane-type sesquiterpenes from the rhizomes of Atractylodes macrocephala and their bioactivities.

Fifteen undescribed eudesmane-type sesquiterpenes, named atramacronoids D-R, along with fourteen known analogues were isolated from the rhizomes of Atractylodes macrocephala. The structures of atramacronoids D-R were elucidated based on extensive spectroscopic data analysis, Snatzke's rule, electronic circular dichroism (ECD) calculations, and X-ray crystallographic analysis. Notably, of the undescribed isolates, atramacronoids D and E are the first example of eudesmanolactam-phenol and eudesmanolactam-ethyl hybrids obtained from plants, respectively. A pair of enantiomers, (+)- and (-)-atramacronoids F, were successfully resolved by chiral-phase HPLC. Atramacronoid D exhibited weak cytotoxicity against SGC-7901 cells. Atramacronoid E significantly promoted the proliferation of LPS-induced IEC-6 cells.

Two new eudesmane sesquiterpene glucosides from the aerial parts of Artemisia vulgaris.

Using combined chromatographic methods, two new sesquiterpene glucosides, vulgarosides A (1) and B (2), and two known analogs ainsliaside E (3) and pumilaside A (4) were isolated from the aerial parts of Artemisia vulgaris. Their chemical structures were established by spectroscopic methods, including one and two-dimensional nuclear magnetic resonance (1 D and 2 D-NMR) spectroscopy and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS). In addition, their cytotoxicity on five human cancer cell lines, including KB (epidermoid carcinoma), HepG2 (hepatocarcinoma), MCF7 (breast carcinoma), SK-Mel-2 (melanoma), and LNCaP (prostate cancer) was also evaluated by the SRB assay. However, none of the tested eudesmane sesquiterpene glycosides showed significant cytotoxicity (IC50>100 µM).

Sesquiterpenoids Isolated from the Rhizomes of Genus Atractylodes.

Atractylodes plants have been used in traditional herbal medicine to treat gastrointestinal diseases and contain various chemical compounds. Sesquiterpenoids are the most important therapeutic compounds in Atractylodes rhizomes. Based on studies reported from 2000 to 2022, we classified sesquiterpenoids by their chemical skeletons and original resources. Moreover, we discussed their biosynthesis and physicochemical and pharmacological features. We reported sesquiterpenoids with skeletal moieties, such as monocyclic sesquiterpenes (bisabolene- and elemene-type), bicyclic sesquiterpenes (eudesmane-, isopterocarpolone-, hydroxycarissone-, eremophilane-, bisesquiterpenoid-, guaiane- and spirovetivane-type and eudesmane lactones) and tricyclic sesquiterpenes (cyperene- and patchoulene-type), with their biosynthetic pathways, chemical modifications and in vivo metabolites. The pharmacological activities of sesquiterpenoids as anti-inflammatory, anti-tumor, anti-diabetic and anti-microbial and for treating gastrointestinal disorders have been reported for this genus.

Croargoids A-G, Eudesmane Sesquiterpenes from the Bark of Croton argyratus.

Seven new sesquiterpenes, named croargoid A-G (1-7), were isolated from the bark of Croton argyratus. Compounds 1-4 were the first examples of eudesmane sesquiterpene lactones containing C5-OH group. Compound 7 was a highly degraded eudesmane sesquiterpene possessing a rare eleven-carbon skeleton. Their structures with stereochemistry were mainly elucidated by NMR analyses in combination with MS and ECD data. Cytotoxicities and NO inhibitions of all isolates were evaluated and only compound 5 showed moderate NO inhibitory activity.

Selective Phytotoxic Effects of Sesquiterpenoids from Sonchus arvensis as a Preliminary Approach for the Biocontrol of Two Problematic Weeds of Wheat.

The objective of this study is to find new selective allelochemicals for managing two problematic weeds redroot pigweed (Amaranthus retroflexus) and common lambsquarters (Chenopodium album) with minimal negative effects on wheat, thereby facilitating the development of eco-friendly botanical herbicide. Three new sesquiterpenoids, sonarvenolide A-C (1-3), and nine known sesquiterpenoids (4-12) were isolated from Sonchus arvensis. Compound 1 was a rare peroxide-substituted eudesmane-type sesquiterpenoid, and compound 3 was a rare iphionane-type sesquiterpenoid. Notably, compounds 1, 3, 4, 6-8, and 11 showed selectivity phytotoxic activity. In particular, compounds 1, 3, and 4 exhibited excellent germination inhibitory effect on A. retroflexus (IC50 = 32.0-129.0 µM), higher than that of the positive control triasulfuron (IC50 = 141.7 µM), and compound 4 showed excellent inhibition on C. album (IC50 = 82.0 µM), higher than that of triasulfuron (IC50 = 100.9 µM). In addition, compounds 1, 3, and 4 showed allelopathy to the growth of two weeds, which were more potent than or close to that of triasulfuron. Furthermore, these compounds were not toxic to wheat even at a high concentration (1000 µM). Structure-activity relationships (SARs) revealed that the presence of peroxides or the absence of hydroxyl at C-5 in the eudesmane-type sesquiterpenoids could strengthen the inhibitory activities. The discovery of selective allelochemicals provides not only a new choice to control two problematic weeds of wheat but also new natural lead compounds for herbicides.

Chlorahupetenes A-D, Four Eudesmane-Type Sesquiterpenoid Dimer Enantiomers with Two Unusual Carbon Skeletons from Chloranthus henryi Var. hupehensis.

(+)- and (-)-Chlorahupetenes A (1a and 1b), B (2a and 2b), C (3a and 3b), and D (4a and 4b), four unique enantiomeric pairs of eudesmane-type sesquiterpenoid dimers with two new carbon skeletons, were isolated from the aerial parts of Chloranthus henryi var. hupehensis. Compounds 1 and 2 possess an unprecedented 6/6/5/6/6 pentacyclic carbon skeleton with a new dimerization pattern of two eudesmane-type sesquiterpenoids. Compounds 3 and 4, which are fused with two eudesmane-type sesquiterpenoids via an unprecedented five-membered O-heterocyclic ring, represent a new 6/6/5/5/6/6/5 heptacyclic ring system. The structures of the compounds were determined through spectroscopic data and X-ray crystallography. Compounds 1a-3b significantly inhibited NO production with IC50 values ranging from 9.62 to 12.91 µM. Moreover, compounds 1b and 3a suppressed the production of a proinflammatory mediator (TNF-α) and enzyme expression (iNOS) at the mRNA level.