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.

Two new eudesmane-type sesquiterpene derivatives from Lecokia cretica (Lam.) DC

Two new sesquiterpene glucosides, 1α,6β,9β-trihydroxy-eudesm-4(15)-en-1,6-O-β-diglucopyranoside (1) and 1α,6β,9β-trihydroxy-eudesm-3-en-1,6-O-β-diglucopyranoside (2) were obtained along with the 1α,6β,9β-trihydroxy-5,10-bis-epi-eudesm-3-en-6-O-β-D-glucopyranoside (3), chlorogenic acid (4), luteolin 7-O-rutinoside (5) and luteolin 7-O- glucoside (6) from the whole plant parts of Lecokia cretica. Their structures were determined on the basis of 1 D, 2 D NMR and HRMS analyses. The in vitro cytotoxic activity of compounds 1-3 against human lung cancer cells (A549) and normal human lung cells (BEAS-2B) was determined using the MTT colorimetric assay. All the tested eudesmane derivatives were found to be inactive.

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.

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.

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.

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).

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.

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

Atractylodin and β-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 β-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). β-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 β-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 β-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.

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.

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.

Two new dinor-eudesmane sesquiterpenoids from the roots of Chloranthus multistachys

Two new dinor-eudesmane sesquiterpenoids, named multistalin A (1), and multistalin B (2), together with three sesquiterpene glycosides (3-5), and a norlabdane-type diterpene (6) were isolated from the root extract of Chloranthus multistachys Pei. Their structures were elucidated on the basis of spectroscopic analysis including 1D, 2D NMR techniques and HR-ESI-MS. In addition, the cytotoxicity activities of the isolated compounds against selected cancer cells (Hela and A-549) were evaluated by MTT assay.

Antifungal effects of alantolactone on Candida albicans: An in vitro study

The human fungal pathogen Candida albicans can cause many kinds of infections, including biofilm infections on medical devices, while the available antifungal drugs are limited to only a few. In this study, alantolactone (Ala) demonstrated antifungal activities against C. albicans, as well as other Candida species, with a MIC of 72 μg/mL. Ala could also inhibit the adhesion, yeast-to-hyphal transition, biofilm formation and development of C. albicans. The exopolysaccharide of biofilm matrix and extracellular phospholipase production could also be reduced by Ala treatment. Ala could increase permeability of C. albicans cell membrane and ROS contribute to the anti-biofilm activity of Ala. Overall, the present study suggests that Ala may provide a promising candidate for developing antifungal drugs against C. albicans infections.

Cardioprotective effects of alantolactone on isoproterenol-induced cardiac injury and cobalt chloride-induced cardiomyocyte injury

OBJECTIVES

Alantolactone (AL) is a compound extracted from the roots of Inula Racemosa that has shown beneficial effects in cardiovascular disease. However, the cardioprotective mechanism of AL against hypoxic/ischemic (H/I) injury is still unclear. This research aimed to determine AL's ability to protect the heart against isoproterenol (ISO)-induced MI injury in vivo and cobalt chloride (CoCl2) induced H/I injury in vitro.

METHODS

Electrocardiography (ECG), lactate dehydrogenase (LDH), creatine kinase (CK), and cardiac troponin I (cTnI) assays in addition to histological analysis of the myocardium were used to investigate the effects of AL in vivo. Influences of AL on L-type Ca2+ current (ICa-L) in isolated rat myocytes were observed by the patch-clamp technique. Furthermore, cell viability, apoptosis, oxidative stress injury, mitochondrial membrane potential, and intracellular Ca2+ concentration were examined in vitro.

RESULTS

The results indicated that AL treatment ameliorated the morphological and ECG changes associated with MI, and decreased levels of LDH, CK, and cTnI. Furthermore, pretreatment with AL elevated antioxidant enzyme activity and suppressed ROS production. AL prevented H/I-induced apoptosis, mitochondria damage, and calcium overload while reducing ICa-L in a concentration and time dependent fashion. The 50% inhibiting concentration (IC50) and maximal inhibitory effect (Emax) of AL were 17.29 μmol/L and 57.73 ± 1.05%, respectively.

CONCLUSION

AL attenuated MI-related injury by reducing oxidative stress, apoptosis, calcium overload, and mitochondria damage. These cardioprotective effects may be related to the direct inhibition of ICa-L.

Sesquiterpenoids and their glycosides from Dobinea delavayi (Baill.) Baill

Eight undescribed sesquiterpenoids, including two eudesmane glycosides dobinosides A and B, five eudesmane aglycones dobinins Q-U, and one germacrane dobinin P, were isolated from the 80% ethanol extract of roots of Dobinea delavayi. Their structures were elucidated by extensive spectroscopic data (1D and 2D NMR, HR-ESI-MS) and single-crystal X-ray diffraction analysis. Dobinoside A, dobinins Q and R, as well as six reported eudesmane sesquiterpenoids, were evaluated for their in vivo antimalarial activities against Plasmodium yoelii BY265RFP in mice. A summary of preliminary structure-activity relationship of eudesmane sesquiterpenoids for in vivo antimalarial activity was described.

[New eudesmane sesquiterpenoids from Atractylodis Macrocephalae Rhizoma and their inhibitory activities against SREBPs]

Three sesquiterpenoids were isolated and purified from the 95% ethanol extract of Atractylodis Macrocephalae Rhizoma by column chromatography on silica gel, Sephadex LH-20, ODS, and high-performance liquid chromatography(HPLC). Their chemical structures were identified on the basis of spectroscopic analysis and physiochemical properties as(7Z)-8β,13-diacetoxy-eudesma-4(15),7(11)-diene(1), 7-oxo-7,8-secoeudesma-4(15),11-dien-8-oic acid(2), and guai-10(14)-en-11-ol(3). Compounds 1 and 2 are new compounds and compound 3 was obtained from Compositae family for the first time. Compounds 1, 2, and 3 showed weak inhibitory activities against sterol regulatory element-binding proteins(SREBPs).

Alantolactone alleviates collagen-induced arthritis and inhibits Th17 cell differentiation through modulation of STAT3 signalling

CONTEXT

Alantolactone, the bioactive component in Inula helenium L. (Asteraceae), exhibits multiple biological effects.

OBJECTIVE

We aimed to determine the anti-inflammatory effect of alantolactone in a collagen-induced arthritis (CIA) mouse model and its immunomodulatory effects on Th17 differentiation.

MATERIALS AND METHODS

A CIA mouse model was established with DBA/1 mice randomly divided into four groups (n = 6): healthy, vehicle and two alantolactone-treated groups (25 or 50 mg/kg), followed by oral administration of alantolactone to mice for 21 consecutive days after arthritis onset. The severity of CIA was evaluated by an arthritic scoring system and histopathological examination. Levels of cytokines and anti-CII antibodies as well as percentages of splenic Th17 and Th17 differentiation with or without alantolactone treatments (0.62, 1.2 or 2.5 μM) were detected with ELISA and flow cytometry, respectively. Western blot analysis was used to evaluate intracellular signalling in alantolactone-treated spleen cells.

RESULTS

In CIA mice, alantolactone at 50 mg/kg attenuated RA symptoms, including high arthritis scores, infiltrating inflammatory cells, synovial hyperplasia, bone erosion and levels of the proinflammatory cytokines TNF-α, IL-6 and IL-17A, but not IL-10 in paw tissues. Alantolactone also reduced the number of splenic Th17 cells and the capability of naïve CD4⁺ T cells to differentiate into the Th17 subset by downregulating STAT3/RORγt signalling by as early as 24 h of treatment.

DISCUSSION AND CONCLUSIONS

Alantolactone possesses an anti-inflammatory effect that suppresses murine CIA by inhibiting Th17 cell differentiation, suggesting alantolactone is an adjunctive therapeutic candidate to treat rheumatoid arthritis.

Eudesmane-type and agarospirane-type sesquiterpenes from agarwood of Aquilaria agallocha

Eleven previously unreported sesquiterpenes, including nine eudesmane-type (agalleudesmanol A-I) and two agarospirane-type sesquiterpenes (agarospiranic aldehyde A-B), together with eight known sesquiterpenes, were isolated from the agarwood of Aquilaria agallocha Roxb. The structures were established based on extensive spectroscopic analyses, including infrared (IR), high-resolution electrospray ionisation mass spectrometry (HRESIMS), nuclear magnetic resonance (NMR), X-ray diffraction, quantum chemical calculations based on empirical electronic circular dichroism (ECD) data, and DP4+ probability analysis. The bioactivity of these undescribed compounds against lipopolysaccharide (LPS)-induced NO production in RAW 264.7 cells was evaluated. Compounds 1 and 2 exhibited significant anti-inflammatory activities, with IC₅₀ values of 5.46-14.07 μM (aminoguanidine as positive control, IC₅₀ 20.33 ± 1.08 μM).

β-eudesmol but not atractylodin exerts an inhibitory effect on CFTR-mediated chloride transport in human intestinal epithelial cells

Oriental herbal medicine with the two bioactive constituents, β-eudesmol (BE) and atractylodin (AT), has been used as a remedy for gastrointestinal disorders. There was no scientific evidence reporting their antidiarrheal effect and underpinning mechanisms. Therefore, we aimed to investigate the anti-secretory activity of these two compounds in vitro. The inhibitory effect of BE and AT on cAMP-induced Cl^- secretion was evaluated by Ussing chamber in human intestinal epithelial (T84) cells. Short-circuit current (I_SC) and apical Cl^- current (I_Cl-) were measured after adding indirect and direct cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel activator. MTT assay was used to determine cellular cytotoxicity. Protein-ligand interaction was investigated by in silico molecular docking analysis. BE, but not AT concentration-dependently (IC₅₀ of ~1.05 µM) reduced cAMP-mediated, CFTR_inh-172 inhibitable Cl^- secretion as determined by transepithelial I_SC across a monolayer of T84 cells. Potency of CFTR-mediated I_Cl- inhibition by BE did not change with the use of different CFTR activators suggesting a direct blockage of the channel active site(s). Pretreatment with BE completely prevented cAMP-induced I_Cl-. Furthermore, BE at concentrations up to 200 µM (24 h) had no effect on T84 cell viability. In silico studies indicated that BE could best dock onto dephosphorylated structure of CFTR at ATP-binding pockets in nucleotide-binding domain (NBD) 2 region. These findings provide the first evidence for the anti-secretory effect of BE involving inhibition of CFTR function. BE represents a promising candidate for the therapeutic or prophylactic intervention of diarrhea resulted from intestinal hypersecretion of Cl^.

Anti-inflammatory Eudesmane Sesquiterpenoids from Artemisia hedinii

Fourteen new eudesmane sesquiterpenoids (1, 3-5, 7-16) and seven known analogues were isolated from the whole plant of Artemisia hedinii. Their structures were elucidated by spectroscopic data analysis and comparison with published NMR data, and their absolute configurations were confirmed by X-ray diffraction experiments and TDDFT ECD calculation. Compounds 1-15 were identified as eudesmane acids, which represent a kind of lactone ring-opening eudesmane-type sesquiterpenes with an acetoxyl or a hydroxy group attached to C-9. Compounds 1 and 2, 5 and 6, and 7 and 8 are three pairs of epimers isomerized at C-3, C-5, and C-11, respectively. Compounds 1-9, 11-13, 15-19, and 21 could influence the proinflammatory phenotype of the M1 macrophage. Among them, compounds 5, 8, 9, 12, 16, and 19 consistently exhibited anti-inflammatory effects, as evidenced by downregulating classic pro-inflammatory cytokines TNF-α, IL-12, IL-6, and IFN-γ in LPS-induced primary bone marrow derived M1 macrophages.

Anti-angiogenic effects of beta-eudesmol and atractylodin in developing zebrafish embryos

Angiogenesis is the process of formation of new blood vessels which plays an essential role in the normal physiological development of the organs and systems. Several factors contribute to and regulate this process. Unregulated angiogenesis, however, is harmful and is usually found in tumors and cancerous cells. β-Eudesmol and atractylodin are sesquiterpenoid contents extracted from the rhizome of Atractylodes lancea (AL). Reports suggest potential anti-angiogenic activities of both compounds. In this study, the anti-angiogenic activities of both compounds were investigated using the well-established zebrafish in vivo model. Zebrafish embryos were treated with a series of concentrations (6.3, 12.5, 25, and 50 μM) of β-eudesmol and (6.3, 12.5, and 25 μM) of atractylodin up to 72 h post-fertilization. Assessment of the effects on phenotypic blood vessel development (sub-intestinal vessel intersection count) revealed that both the compounds inhibited vessel development, particularly at higher concentrations. At the genetic levels, only β-eudesmol significantly downregulated the expression of the Vegfaa gene and also its receptor Vegfr2. β-Eudesmol also affected the expression of Vegfaa protein in a concentration-dependent manner. Results indicate that β-eudesmol exerts anti-angiogenic property through inhibition of Vegfaa at both the gene and protein levels. However, atractylodin does not possess this property.

Synthesis of Active Strigolactone Analogues Based on Eudesmane- and Guaiane-Type Sesquiterpene Lactones

Strigolactones are natural products that are exuded by plants and stimulate parasitic weed germination. Their use in herbicides is limited since they are produced in small quantities, but the synthesis of bioactive analogues provides an alternative source. In this work, eleven analogues have been synthesized. Among them, nine compounds belong to a novel family named eudesmanestrigolactones. The procedure is short (3-6 steps), the starting materials are isolated on a multigram scale, and global yields are up to 8%, which significantly enhance isolated yields. In bioassay, the compounds germinated high percentages of Phelipanche ramosa, Orobanche cumana, and Orobanche crenata seeds, even at nanogram doses (100 nM). Bioactivity was stereochemistry-dependent, and it was discussed in terms of the presence and geometry of the enol ether, orientation of the butenolide, and unsaturation of ring A. The reported compounds provide a set of readily obtained allelochemicals with potential applications as preventive herbicides.

Oxygenated Geosmins and Plant-like Eudesmanes from a Bacterial Mangrove Endophyte

Geosmin (1) is a microbial terpene metabolite that is responsible for the typical smell of soil and causes an off-odor of food and water. Eudesmane sesquiterpenes are commonly found in plant essential oils. Here we describe the discovery of four geosmin-type metabolites, 7R-hydroxygeosmin (2), 3-oxogeosmin (3), 2R-hydroxy-7-oxogeosmin (4), 5-deoxy-7β,9β-dihydroxygeosmin (5), the plant-like eudesmanes 4β,10α-eudesmane-5β,11-diol (6) and (1S,5S,6S,7S,10S)-10α-eudesm-4(15)-ene-1α,6α-diol (7), and the known 1(10)E,5E-germacradiene-2,11-diol (8) from a bacterial endophyte (Streptomyces sp. JMRC:ST027706) of the mangrove plant Bruguiera gymnorrhiza. By means of NMR, MS, and ECD spectroscopy, all chemical structures as well as the absolute configurations for the new compounds were elucidated. Compounds 2-5 represent the first geosmin-related metabolites directly as bacterial natural products. The plant-derived eudesmane-5β,11-diol (6) and (1S,5S,6S,7S,10S)-10α-eudesm-4(15)-ene-1α,6α-diol (7) are also now reported as bacterial products. The broad antimicrobial activities of 6 against a suite of fungal and bacterial pathogens including methicillin-resistant Staphylococcus aureus suggest that this terpene could be an important active principle of the medicinal plant Cymbopogon distans. The discovery of geosmin metabolites from one actinomycete indicated that these bacteria could possess enzymes for modifying geosmin and offer a possibility for bioremediation.

Nanoemulsions with oleoresin of Copaifera reticulata (Leguminosae) improve anthelmintic efficacy in the control of monogenean parasites when compared to oleoresin without nanoformulation

This study compared the in vitro anthelmintic activity of Copaifera reticulata oleoresin (200, 400, 600, 800 and 1,000 mg/L) and of nanoemulsions prepared with this oleoresin (50, 100, 150, 200 and 250 mg/L) against monogeneans on the gills of Colossoma macropomum. The major compounds present in the oleoresin of C. reticulata were γ-macrocarpene (14.2%), α-bergamotene (13.6%), β-selinene (13.4%) and β-caryophyllene (11.7%). All concentrations of the nanoemulsion and the oleoresin without nanoformulation showed anthelmintic efficacy against monogeneans, and higher concentrations led to more rapid parasite mortality. Structural damages to the tegument of the parasites exposed to C. reticulata oleoresin were observed with scanning electron microscopy. At two hours of exposure, fish showed 100% tolerance to all nanoemulsion concentrations used in the in vitro assays, whereas 100% mortality was shown in the fish exposed to the oleoresin without nanoformulation after one hour. The results of this study suggest that nanoemulsions with oleoresin of C. reticulata have advantages in the control and treatment of monogenean infections in C. macropomum when compared to the oleoresin without nanoformulation. In addition, since nanoemulsions with the C. reticulata oleoresin are safe to control monogeneans, the efficacy of these nanoformulations may be assayed in therapeutic baths to treat C. macropomum infected by monogeneans.

Antimalarial Eudesmane Sesquiterpenoids from Dobinea delavayi

Eleven new angeloylated eudesmane sesquiterpenoids, dobinins D-N (2, 3, 5, 6, 8, 9, and 11-15), and four known compounds (1, 4, 7, and 10) were isolated from the roots of Dobinea delavayi. A new oxidation product (8a) was also obtained from dobinin H (8). Their structures were elucidated by spectroscopic data and single-crystal X-ray diffraction analyses. Dobinins K-N (12-15) are the first examples of rearrangement noreudesmane analogue sesquiterpenoids with a unique 6/5-fused carbon skeleton. A putative biosynthetic pathway of compounds 12-15 is proposed. Compound 12 exhibited significant antimalarial activity superior to artemisinin with the inhibition ratio of 59.1%, and compounds 3, 5, and 15 exhibited moderate antimalarial activities against Plasmodium yoelii BY265RFP with inhibition ratios ranging from 14.5% to 18.5% at a dose of 30 mg/kg/day. In addition, the apoptosis of P. yoelii BY265RFP by the depolarization of mitochondrial membrane potential with striking ROS production, after parasitized erythrocyte lysis mediated by cytokines IL-12 and IFN-γ, may be a possible mechanism of antimalarial action of compound 12 against P. yoelii BY265RFP.

Alantolactone suppresses inflammation, apoptosis and oxidative stress in cigarette smoke-induced human bronchial epithelial cells through activation of Nrf2/HO-1 and inhibition of the NF-κB pathways

BACKGROUND

It is well established that airway remodeling and inflammation are characteristics for chronic obstructive pulmonary disease (COPD). Moreover, cigarette smoke extract (CSE) promots inflammation, apoptosis and oxidative stress in COPD. And, there is evidence suggested that alantolactone (ALT), a sesquiterpene lactone isolated from Inula helenium, plays an adverse role in inflammation, apoptosis and oxidative stress. However, few studies have investigated the function and mechanism of ALT treatment on the COPD pathological process.

METHODS

The levels of IL-1 β, TNF-α, IL-6 and IFN-γ were examined by ELISA. Cells' apoptosis and caspase-3 activity were detected by Cell Death Detection PLUS enzyme-linked immunosorbent assay and caspase-Glo 3/7 Assay, respectively. The content of malondialdehyde (MDA) and superoxide dismutase (SOD) were determined by using MDA and SOD assay kits. Reactive oxygen species (ROS) generation was measured by DCFH-DA assay. Protein expression was assayed by Western blot.

RESULTS

In the present study, we aimed to observe the protective effects of ALT against inflammation, apoptosis and oxidative stress in human bronchial epithelial Beas-2B and NHBE cells. Our results showed that different doses of CSE exposure induced Beas-2B and NHBE cell inflammatory cytokines IL-1 β, TNF-α, IL-6 and IFN-γ expression, cell apoptosis, caspase-3 activity and mediated oxidative stress markers MDA, ROS and SOD levels, while ALT treatment counteracted the effects of CSE. Further studies suggested that ALT attenuated NF-κB pathway activation. ALT also activated the Nrf2/HO-1 signal pathway through promoting Nrf2 nuclear aggregation and downstream HO-1 protein expression. HO-1 inhibitor tin protoporphyrin IX (SnPP IX) reversed the effects of ALT on Beas-2B and NHBE cell inflammation, apoptosis and oxidative stress.

CONCLUSIONS

The above results collectively suggested that ALT suppressed CSE-induced inflammation, apoptosis and oxidative stress by modulating the NF-ĸB and Nrf2/ HO-1 axis.

Inula helenium and Grindelia squarrosa as a source of compounds with anti-inflammatory activity in human neutrophils and cultured human respiratory epithelium

ETHNOPHARMACOLOGICAL RELEVANCE

During the epidemic season, over 90% of acute wheezing disease is associated with bronchial inflammation. Both neutrophil- and eosinophil-mediated inflammation have been involved in the pathophysiology of acute bronchitis, but neutrophil cell recruitment has been shown to be dominant. The ongoing inflammation increases the chemotaxis of neutrophils to inflamed site providing to their overaccumulation. The pharmacological reduction of neutrophil migration can be limited by suppression of major chemo-attractants and cytokines (IL-8, IL-1β and TNF-α) release and downregulation of adhesive molecules.

AIM OF THE STUDY

During a screening of plants traditionally used in respiratory tracts diseases (e.g. cough, rhinitis, bronchitis, throat infection, fever, influenza) in Europe, we have selected roots of Inula helenium and aerial parts of Grindelia squarrosa as a potential source of compounds limiting neutrophil migration.

MATERIALS AND METHODS

The effect on IL-8, IL-1β and TNF-α release by neutrophils and respiratory epithelium cell line (A549) was measured by enzyme-linked immunosorbent assay (ELISA). The surface expression of adhesive molecules was analyzed with flow cytometry, and the neutrophil attachment to the epithelial cells was assessed fluorimetrically.

RESULTS

We confirmed the ability of selected extracts and compounds to suppress neutrophil binding to the epithelium surface via downregulation of β2 integrin. Alantolactone and grindelic acid have shown significant suppression of IL-8, TNF-α and IL-1β release comparable with budesonide, used as a positive control.

CONCLUSIONS

The present study demonstrated that Inula helenium and Grindelia squarrosa, which have been traditionally used in Europe as medicinal plants, are a valuable source of active compounds with anti-inflammatory activity. Our observations justify the traditional use of I. helenium and G. squarrosa for a treatment of inflammation-based diseases in respiratory tract.

Nanoformulated Codelivery of Quercetin and Alantolactone Promotes an Antitumor Response through Synergistic Immunogenic Cell Death for Microsatellite-Stable Colorectal Cancer

Microsatellite-stable colorectal cancer (CRC) is known to be resistant to immunotherapy. The combination of quercetin (Q) and alantolactone (A) was found to induce synergistic immunogenic cell death (ICD) at a molar ratio of 1:4 (Q:A). To achieve ratiometric loading and delivery, the micellar delivery of Q and A (QA-M) was developed with high entrapment efficiency and drug loading at an optimal ratio. QA-M achieved prolonged blood circulation and increased tumor accumulation for both drugs. More importantly, QA-M retained the desired drug ratio (molar ratio of Q to A = 1:4) in tumors at 2 and 4 h after intravenous injection for synergistic immunotherapy. Tumor growth was significantly inhibited in murine orthotopic CRC by the treatment of QA-M compared to PBS and the combination of free drugs (p < 0.005). The combination of nanotherapy stimulated the host immune response to induce long-term tumor destruction and induced memory tumor surveillance with a 1.3-fold increase in survival median time compared to PBS (p < 0.0001) and a combination of free drugs (p < 0.0005). The synergistic therapeutic effect induced by codelivery of Q and A is capable of reactivating antitumor immunity by inducing ICD, causing cell toxicity and modulating the immune-suppressive tumor microenvironment. Such a combination of Q and A with synergistic effects entrapped in a simple and safe nanodelivery system may provide the potential for scale-up manufacturing and clinical applications as immunotherapeutic agents for CRC.

Alantolactone exhibits selective antitumor effects in HELA human cervical cancer cells by inhibiting cell migration and invasion, G2/M cell cycle arrest, mitochondrial mediated apoptosis and targeting Nf-kB signalling pathway

PURPOSE

Cervical cancer is responsible for significant mortality and morbidity across the globe. Owing to the adverse effects of the currently used chemotherapy, research is directed to develop effective and safer chemotherapy for cervical cancer. This study was therefore designed to examine the effects of Alantolactone (AL) against a panel of human cervical cancer cells (HeLa, C4-1, MEK-180, C33A) and a normal cell line (HCerEPiC).

METHODS

Cell viability was examined by WST-1 assay. Cell migration and invasion were examined by transwell assay. Cell cycle analysis was performed by flow cytometry. Apoptosis was detected by annexin V/propidium iodide (PI) and DAPI staining. Western blot analysis was used to examine protein expression.

RESULTS

The results revealed that AL inhibits the growth of the all the cervical cancer cells in a concentration -dependent manner and exhibited the lowest IC50 of 15 µM against the HeLa cervical cancer cells. The anticancer effects of AL were due to induction of mitochondrial mediated apoptosis. AL caused enhancement in the expression of apoptosis regulatory proteins such as caspase 3 and Bax in cervical cancer cells. AL not only prompted the accumulation of the cervical cancer cells in the G2/M phase of the cell cycle but also inhibited the expressions of various cyclins. Transwell assay revealed that AL suppresses the migration and invasion of cervical cancer cells. Moreover AL could also block the NF-kB signalling pathway concentration-dependently.

CONCLUSIONS

It is concluded that AL may serve as an important lead molecule for the development of therapy for cervical cancer.

Eudesmane Glycosides from Ambrosia artemisiifolia (Common Ragweed) as Potential Neuroprotective Agents

In Alzheimer's disease, amyloid-β (Aβ) accumulation in the brain results in neuronal cell death and is one of the major causes of dementia. Because the current therapeutic agents are not yet sufficiently effective or safe, there have been attempts to find new neuroprotective chemicals against Aβ-induced cytotoxicity. A 70% EtOH extract of whole plants of Ambrosia artemisiifolia (common ragweed) was selected after the screening of a natural extract library. Seven new eudesmane-type glycosides (1-7) and seven known compounds (8-14) were obtained through bioactivity-guided fractionation from the aerial parts of this plant. Their structures were determined on the basis of their nuclear magnetic resonance spectra, high-resolution electrospray ionization mass spectrometry analysis, and electronic circular dichroism calculations. Among them, compounds 1, 2, 4-6, 8, 9, 11, 13, and 14 showed protective effects against Aβ-induced cytotoxicity in Aβ₄₂-transfected HT22 cells. The most active compounds, 5 and 6, exhibited moderate protective activity dose-dependently (10, 20, and 40 μM).

Alantolactone induces apoptosis and suppresses migration in MCF‑7 human breast cancer cells via the p38 MAPK, NF‑κB and Nrf2 signaling pathways

Human breast cancer is a malignant type of cancer with high prevalence. In the present study, the anticancer effects of alantolactone, a sesquiterpene lactone, on the human breast cancer cell line MCF‑7 were investigated in vitro. The MCF‑7 cell morphology changed from diamond to round subsequent to treatment with alantolactone, and the cell viability reduced significantly compared with that of the control cells. Alantolactone induced apoptosis of MCF‑7 cells by regulating the protein expression levels of B‑cell lymphoma 2 (Bcl‑2), Bcl‑2‑associated X protein, p53, caspase‑3 and caspase‑12, which are associated with the apoptotic pathway, and suppressed colony formation and migration by regulating the protein expression of matrix metalloproteinase (MMP)‑2, MMP‑7 and MMP‑9. Cell signaling pathway analysis confirmed that alantolactone increased the phosphorylation of p38, and decreased the nuclear expression levels of p65 and nuclear factor erythroid 2‑related factor 2 (Nrf2), suggesting that the apoptosis‑promoting and migration‑suppressing effect of alantolactone may partially depend on regulating the p38 MAPK, NF‑κB and Nrf2 pathways. These results also suggested that alantolactone may become a potential therapeutic strategy for treating breast cancer.

New Eudesmane-Type Sesquiterpenoids from the Mangrove-Derived Endophytic Fungus Penicillium sp. J-54

Four new eudesmane-type sesquiterpenoids, penicieudesmol A–D (1–4), were isolated from the fermentation broth of the mangrove-derived endophytic fungus Penicillium sp. J-54. Their structures were determined by spectroscopic methods, the in situ dimolybdenum CD method, and modified Mosher’s method. The bioassays results showed that 2 exhibited weak cytotoxicity against K-562 cells.

Eudesmane-Type Sesquiterpene Glycosides from Dictamnus dasycarpus Turcz

Eudesmane-type sesquiterpenes have been reported to exhibit varieties of biological activities. During the process of investigating this kind of natural product from the root bark of Dictamnus dasycarpus Turcz., 13 eudesmane-type sesquiterpene glycosides including six new isolates, named as dictameudesmnosides A₁ (1), A₂ (2), B (3), C (4), D (5), and E (6), together with seven known ones (7-13), were obtained. Herein, their structures were determined by the analysis of physical data, spectroscopic analysis, and chemical methods. The existence of α-configuration glucose units in their structures (1-5, 8) is not very common in natural glycosidic components. Meanwhile, compounds 3-5, 7, and 9-13 displayed TG accumulation inhibitory effects on HepG2 cells.

Anti-allergic effects of sesquiterpene lactones from Saussurea costus (Falc.) Lipsch. determined using in vivo and in vitro experiments

ETHNOPHARMACOLOGICAL RELEVANCE

Saussurea costus (Falc.) Lipsch. root has been used in Asian traditional medicine for the treatment of asthma, rheumatism, and other conditions. S. costus extracts were shown to alleviate house dust mite-induced atopic-like dermatitis in Nc/Nga mice; besides, sesquiterpene lactones were isolated from S. costus extracts.

AIMS OF THE STUDY

We aimed to investigate the effects of sesquiterpene lactones (alantolactone, costunolide, and dehydrocostuslactone) in allergic asthma using female Balb/c mice and rat RBL-2H3 mast cells.

MATERIALS AND METHODS

Antigen-induced degranulation was assessed by measuring β-hexosaminidase activity in vitro. In addition, a murine ovalbumin-induced allergic asthma model was used to test the in vivo efficacy of sesquiterpene lactones.

RESULTS

Sesquiterpene lactones inhibited antigen-induced degranulation, wherein dehydrocostuslactone > costunolide > alantolactone in potency. Administration of sesquiterpene lactones decreased the number of immune cells, particularly eosinophils, and reduced the expression and secretion of Th2 cytokines (IL-4 and IL-13) in the bronchoalveolar lavage fluid and lung tissues of mice with ovalbumin-induced allergic asthma. Histological studies showed that sesquiterpene lactones reduced inflammation and mucin production in the lungs. Similar to the in vitro study, dehydrocostuslactone showed the highest potency, followed by costunolide and alantolactone.

CONCLUSION

These findings provide evidence that sesquiterpene lactones might be potential anti-allergic therapeutics.

Antiproliferative metabolites from the Northern African endemic plant Daucus virgatus (Apiaceae)

Chemical analysis of the dichloromethane fraction obtained from aerial parts of the Northern African endemic plant Daucus virgatus led to the isolation of three previously undescribed sesquiterpenoids, namely the daucane vaginatin B, a eudesmane and the elemane elemavirgolide, along with five known metabolites. The structures of these compounds were determined by a detailed MS and NMR analysis and they were evaluated for antiproliferative activity against three human cell lines, A375 (melanoma), MCF-7 (breast adenocarcinoma), and HACAT (keratinocyte). The phytoalexin 6-methoxymellein revealed a previously unreported antiproliferative activity, while the eudesmane and the elemane derivatives exhibited a selective activity (SI = 11.1 and 3.3, respectively) against melanoma tumor cell lines.

Semisynthesis, an Anti-Inflammatory Effect of Derivatives of 1β-Hydroxy Alantolactone from Inula britannica

1β-hydroxy alantolactone, a sesquiterpene lactone mainly isolated from Inula genus plants, exhibits potent anti-inflammatory and anticancer activities. In this work, 1β-hydroxy alantolactone was isolated and five derivatives were prepared through different reactions at the C1-OH and C13-methylene motifs. The structure-activity relationships (SAR) of anti-inflammatory effects against NO production in RAW264.7 cells showed that the α-methylene-γ-butyrolactone motif was essential for NO production suppression and that retaining the C1-OH group can remarkably improve this effect. The NF-κB signaling pathway plays a pivotal role in the regulation of NO expression. Moreover, the levels of p65 and p50 phosphorylation were investigated and active compound 1 inhibited phosphorylation of p65 and p50 in TNF-α-induced NF-κB signaling. Further molecular docking suggested that 1 may target the p65 of NF-κB.

Anti-inflammatory Activity of Eudesmane-Type Sesquiterpenoids from Salvia plebeia

Nine new sesquiterpenoid lactones and 11 known analogues were isolated from the aerial parts of Salvia plebeia R.Br. Their structures were elucidated via HRESIMS and NMR data, and their absolute configurations were defined via electronic circular dichroism data, X-ray crystallographic analysis, and the modified Mosher's ester method. Compounds 1-20 were investigated for their ability to inhibit LPS-stimulated nitric oxide production in murine macrophage cells. Of the isolates, epi-eudebeiolide C (20) showed the highest inhibitory effect (IC₅₀ of 17.9 μM). mRNA and protein expression of inducible nitric oxide synthase (iNOS), but not that of cyclooxygenase-2 (COX-2), was dose-dependently decreased by 20 in LPS-activated RAW 264.7 cells. Based on a mechanistic study involving the nuclear factor-κB (NF-κB) signaling pathway, the anti-inflammatory effect of 20 was attributed to NF-κB activation blockade via inhibition of NF-κB (IκB) phosphorylation. Therefore, 20 might be a potential candidate for relieving inflammatory diseases.

Isolation of eudesmanes from Pluchea odorata and evaluation of their effects on cancer cell growth and tumor invasiveness in vitro

The traditionally used Central American medicinal plant Pluchea odorata, known as an anti-inflammatory and cancer cell growth-inhibiting remedy, was subjected to bioassay-guided isolation. Structure elucidation by 1D- and 2D-NMR and MS techniques supported by ECD and UV spectroscopic data revealed seven structurally previously undescribed and eight known eudesmane-type sesquiterpenes. Furthermore, one previously undescribed and one known phytol-like alcohol were identified. All compounds were tested for their cytotoxicity in cancer cells and for their anti-invasive effects. Among the eudesmanes, 3α-(2',3'-epoxy-2'-methylbutyryloxy)-4α-hydroxy-11-hydroperoxy-eudesm-6-en-8-one exhibited the most potent cytotoxic activity with an IC₅₀ value of 8.8 μM (after 48 h). Also in an in vitro model measuring the tumor-triggered breaching of the adjacent lymph endothelial cell barrier (3S*,4R*,5S*,10S*,2'R*,3'R*)-3-(2',3'-epoxy-2'-methylbutyryloxy)-4,7-dihydroxy-eudesm-11-en-8-one (IC₇₅ = 47 μM) and (3S*,4R*,5R*,10S*,2'R*,3'R*)-3-(2',3'-epoxy-2'-methylbutyryloxy)-4-acetyloxy-6-methoxy-11-hydroxy-eudesm-6-en-8-one (IC₇₅ = 73 μM) showed inhibitory activities. Furthermore, preliminary structure-activity relationships (SARs) of the eudesmanes were developed.

Sesquiterpenoids from the twigs and leaves of Fokienia hodginsii

A rare carotane-type sesquiterpenoid, forkienin A (1), a new eudesmane-type sesquiterpenoid, forkienin B (2), and a new natural eudesmane-type sesquiterpenoid, forkienin C (3), were isolated from the twigs and leaves of Fokienia hodginsii, along with eight known sesquiterpenoids. The structures of the new compounds were elucidated on the basis of their spectroscopic analysis, including 1D and 2D NMR methods. All compounds were evaluated for cytotoxicity against HL-60, SMMC-7721, A-549, MCF-7, and SW480 cell lines.

Eudesmane-type sesquiterpenoids from Salvia plebeia inhibit IL-6-induced STAT3 activation

Seven eudesmane-type sesquiterpenoid lactones and the known plebeiolide C were isolated from an ethanol-soluble extract of the aerial parts of Salvia plebeia R. Br. Their structures were determined via NMR and MS, and their absolute configurations were elucidated using ECD, and X-ray crystallographic analysis, as well as the modified Mosher ester method. All isolates were evaluated for their inhibitory effects on IL6-induced STAT3 promoter activation in stably transfected Hep3B cells. Of these isolates, eudebeiolide D exhibited an inhibitory effect with the IC50 value of 1.1 μM.

Vetiverianines A, B, and C: Sesquiterpenoids from Vetiveria zizanioides Roots

Three new sesquiterpenoids-vetiverianines A (1), B (2), and C (3)-and a known eudesmane sesquiterpenoid (4) were isolated from the roots of Vetiveria zizanioides. Vetiverianine A (1) has a unique carbon framework comprising a rigid tricyclic ring system. Vetiverianines B (2) and C (3) are new eremophilane sesquiterpenoids. The structures of sesquiterpenoids 1-3, including the absolute configurations, were determined by NMR spectroscopic, X-ray crystallography, and vibrational circular dichroism data analysis. Vetiverianine C (3) exhibited weak cytotoxic activity against HL-60 cells.

β-eudesmol, a sesquiterpene from Teucrium ramosissimum, inhibits superoxide production, proliferation, adhesion and migration of human tumor cell

Reactive oxygen species are well-known mediators of various biological responses. Recently, new homologues of the catalytic subunit of NADPH oxidase have been discovered in non phagocytic cells. These new homologues (Nox1-Nox5) produce low levels of superoxides compared to the phagocytic homologue Nox2/gp91phox. In this study we examined the effect of β-eudesmol, a sesquiterpenoid alcohol isolated from Teucrium ramosissimum leaves, on proliferation, superoxide anion production, adhesion and migration of human lung (A549) and colon (HT29 and Caco-2) cancer cell lines. Proliferation of tumor cells was inhibited by β-eudesmol. It also significantly inhibited superoxide production in A549 cells. Furthermore, β-eudesmol inhibited adhesion and migration of A549 and HT29 cell. These results demonstrate that β-eudesmol may be a novel anticancer agent for the treatment of lung and colon cancer by different ways: by inhibition of superoxide production or by blocking proliferation, adhesion and migration.

Bioactive sesquiterpenoids from the flowers of Inula japonica

Phytochemical investigation of the flowers of Inula japonica led to isolation of nine sesquiterpenoids, inujaponins A-I, as well as eighteen known ones. These sesquiterpenoids belong to six skeletal-types, including eudesmane, 1,10-seco-eudesmane, germacrane, guaiane, 4,5-seco-guaiane, and pseudoguaiane sesquiterpenoids. Their structures were established by extensive spectroscopic analysis. The absolute configurations of inujaponin A, eupatolide, and deacetylovatifolin were determined by Cu-Kα X-ray crystallographic analysis. Most of the isolated compounds exhibited potent cytotoxicity against HL-60, SMMC-7721, A-549, MCF-7, and SW-480 cancer cell lines, with IC50 values ranging from 1.57 to 22.58 μM. Some selected compounds also possessed significant inhibitory activity against LPS-induced NO production in RAW264.7 macrophages with IC50 values ranging from 1.42 to 8.99 μM.

ent-Eudesmane-Type Sesquiterpenoids from the Chinese Liverwort Chiloscyphus polyanthus var. rivularis

Seven new ent-eudesmane-type sesquiterpenoids (1-7) and six known analogues (8-13) were isolated from the Chinese liverwort Chiloscyphus polyanthus var. rivularis. Their structures were determined from analysis of MS and NMR spectroscopic data and single-crystal X-ray diffraction. A cytotoxic evaluation showed that compound 1 exhibited weak inhibitory activity against the A549 cancer cell line with an IC50 value of 27.7 µM.

Eucarobustols A-I, Conjugates of Sesquiterpenoids and Acylphloroglucinols from Eucalyptus robusta

Nine new conjugates of sesquiterpenoids and acylphloroglucinols, named eucarobustols A-I (1-9), as well as 11 known analogues were isolated from the leaves of Eucalyptus robusta. The sesquiterpenoid motifs furnishing the new conjugates included four structural types of aristolane (1 and 2), guaiane (3), eudesmane (4), and aromadendrane (5-9) moieties. Compounds 1 and 2 were found to represent the first examples of conjugates of aristolane and acylphloroglucinol units. In turn, compound 3 features a new coupling model of guaiane and acylphloroglucinol via the C-4-C-7' bond. Compounds 1, 7, and 9 showed inhibitory activities against protein tyrosine phosphatase 1B (PTP1B) with IC50 values of 1.3, 1.8, and 1.6 μM, respectively.

Induction of ROS Overload by Alantolactone Prompts Oxidative DNA Damage and Apoptosis in Colorectal Cancer Cells

Cancer cells typically display higher than normal levels of reactive oxygen species (ROS), which may promote cancer development and progression but may also render the cancer cells more vulnerable to further ROS insult. Indeed, many of the current anticancer therapeutics kill cancer cells via induction of oxidative stress, though they target both cancer and normal cells. Recently, alantolactone (ATL), a natural sesquiterpene lactone, has been shown to induce apoptosis by increasing ROS levels specifically in cancer cells; however, the molecular mechanisms linking ROS overproduction to apoptosis remain unclear. Here we show that the ATL-induced ROS overload in human SW480 and SW1116 colorectal cancer cells was followed by a prominent accumulation of cellular oxidized guanine (8-oxoG) and immediate increase in the number of DNA strand breaks, indicating that increased ROS resulted in extensive oxidative DNA damage. Consequently, the G₁/S-CDK suppresser CDKN1B (p21) and pro-apoptotic proteins Bax and activated caspase-3 were upregulated, while anti-apoptotic Bcl-2 was downregulated, which were followed by cell cycle arrest at G₁ and marked apoptosis in ATL-treated cancer but not non-cancer cells. These results suggest that the ATL-induced ROS overload triggers cell death through induction of massive oxidative DNA damage and subsequent activation of the intrinsic apoptosis pathway.

New eudesmane-type sesquiterpenoids from the root bark of Pseudolarix kaempferi

The phytochemical investigation of the root bark of Pseudolarix kaempferi yielded eight eudesmane-type sesquiterpenoids, including three new ones, 1α-hydroxyl-4(14)-en-β-dihydroagarafuran (1), 1α, 2α-diacetoxy-8β-isobutanoyloxy-9α-benzoyl oxy-15-β-(β-furancarbonyloxy)-4β, 6β-dihydroxy-β-dihydroagarofuran (7), and 1α-acetoxy-2 α-furancarbonyloxy-8β-isobutanoyloxy-9α-benzoyloxy-15β-(β-acetoxy)-4β, 6β-dihydroxy-β-dihydroagarofuran (8). Herein the new compounds 7 and 8 were reported as a mixture. The molecular structures of the isolated compounds were elucidated on the basis of extensive spectroscopic analysis, including UV, IR, NMR, and MS, and comparison with the literature data.