Dimerized sesquiterpenoid [4 + 2] adducts with ferroptosis-promoting activity from Inula britannica Linn.

Inubritanolides C and D (1 and 2), two exo sesquiterpenoid [4 + 2] adducts with unprecedented interconverting conformations of twist-chair and chair, together with two previously undescribed endo [4 + 2] dimers (3 and 4) were discovered from Inula britannica flowers. Dimers 1 and 2 have an undescribed carbon skeleton comprising of eudesmanolide and guaianolide units with the linkage mode of C-11/C-1' and C-13/C-3' via a Diels-Alder cycloaddition reaction. Their structures were elucidated using 1D/2D NMR, X-ray diffraction, ECD, and variable-temperature NMR experiments. Dimer 2 displayed a strong inhibitory effect on breast cancer cells by promoting lipid ROS production, showing its potential as ferroptosis inducer.

Cannabinoid Receptor Type II Ligands from Sandalwood Oil and Synthetic α-Santalol Derivatives.

Bioassay-guided fractionation of the essential oil of Santalum album led to the identification of α-santalol (1) and ß-santalol (2) as new chemotypes of cannabinoid receptor type II (CB2) ligands with Ki values of 10.49 and 8.19 µM, respectively. Nine structurally new α-santalol derivatives (4a-4h and 5) were synthesized to identify more selective and potent CB2 ligands. Compound 4e with a piperazine structural moiety demonstrated a Ki value of 0.99 µM against CB2 receptor and did not show binding activity against cannabinoid receptor type I (CB1) at 10 µM. Compounds 1, 2, and 4e increased intracellular calcium influx in SH-SY5Y human neuroblastoma cells that were attenuated by CB2 antagonism or inverse agonism, supporting the results that these compounds are CB2 agonists. Molecular docking showed that 1 and 4e had similar binding poses, exhibiting a unique interaction with Thr114 within the CB2 receptor, and that the piperazine structural moiety is required for the binding affinity of 4e. A 200 ns molecular dynamics simulation of CB2 complexed with 4e confirmed the stability of the complex. This structural insight lays a foundation to further design and synthesize more potent and selective α-santalol-based CB2 ligands for drug discovery.

Phytoecdysteroids from Dianthus superbus L.: Structures and anti-neuroinflammatory evaluation.

Six undescribed C27-phytoecdysteroid derivatives, named superecdysones A-F, and ten known analogs were extracted from the whole plant of Dianthus superbus L. Their structures were identified by extensive spectroscopy, mass spectrometric methods, chemical transformations, chiral HPLC analysis, and the single-crystal X-ray diffraction analysis. Superecdysones A and B possess a tetrahydrofuran ring in the side chain and superecdysones C-E are rare phytoecdysones containing a (R)-lactic acid moiety, whereas superecdysone F is an uncommon B-ring-modified ecdysone. Notably, based on the variable temperature (from 333 K to 253 K) NMR experiments of superecdysone C, the missing carbon signals were visible at 253 K and assigned. The neuroinflammatory bioassay of all compounds were evaluated, and 22-acetyl-2-deoxyecdysone, 2-deoxy-20-hydroxyecdysone, 20-hydroxyecdysone, ecdysterone-22-O-benzoate, 20-hydroxyecdysone-20,22-O-R-ethylidene, and acetonide derivative 20-hydroxyecdysterone-20, 22-acetonide significantly suppressed the LPS-induced nitric oxide generation in microglia cells (BV-2), with IC50 values ranging from 6.9 to 23.0 µM. Structure-activity relationships were also discussed. Molecular docking simulations of the active compounds confirmed the possible mechanism of action against neuroinflammations. Furthermore, none compounds showed cytotoxicity against HepG2 and MCF-7. It is the first report about the occurrence and anti-neuroinflammatory activity of the phytoecdysteroids in the genus Dianthus. Our findings demonstrated that ecdysteroids may be used as potential anti-inflammatory drugs.

Chemical characterization and multifunctional neuroprotective effects of sesquiterpenoid-enriched Inula britannica flowers extract.

Dried flowers of Inula britannica commercially serve as pharmaceutical/nutraceutical herbs in the manufacture of medicinal products and functional tea that has been reported to possess extensive biological property. However, the neuroprotective constituents in I. britannica flowers are not known. In the current study, phytochemicals of sesquiterpenoid-enriched I. britannica flowers extract and their potential multifunctional neuroprotective effects were investigated. Nineteen structurally diverse sesquiterpenoids, including two new sesquiterpenoid dimers, namely, inubritanolides A and B (1, 2), and four new sesquiterpenoid monomers (3-6), namely, 1-O-acetyl-6-O-chloracetylbritannilactone (3), 6-methoxybritannilactone (4), 1-hydroxy-10ß-methoxy-4αH-1,10-secoeudesma-5(6),11(13)-dien-12,8ß-olide (5) and 1-hydroxy-4αH-1,10-secoeudesma-5(6),10(14),11(13)-trien-12,8ß-olide (6), as well as 13 known congeners (7-19) were isolated from this source. The structures of compounds 1-6 were elucidated by 1D- and 2D- NMR and HR-ESI-MS data, and their absolute configurations were discerned by electronic circular dichroism (ECD) data analysis and single crystal X-ray diffraction. Interestingly, inubritannolide A (1) is a new type [4 + 2] Diels-Alder dimer featuring a hepta-membered cycloether skeleton. Most of the compounds showed potential multifunctional neuroprotective effects, including antioxidative, anti-neuroinflammatory, and microglial polarization properties. Specifically, 1 and 6 displayed slight strong neuroprotective potency against different types of neuronal cells mediated by various inducers including H2O2, 6-hydroxydopamine (6-OHDA), and lipopolysaccharide (LPS). Overall, this is the first report on multifunctional neuroprotective effects of sesquiterpenoid-enriched I. britannica flowers extract, which supports its potential pharmaceutical/nutraceutical application in neurodegenerative diseases.

Cytotoxic Diterpenoids from Euphorbia fischeriana.

Five new diterpenoids, named euphorfischerins A-E, were isolated from the roots of Euphorbia fischeriana. Their chemical structures and absolute configurations were determined by interpretation of NMR, HR-ESI-MS, ECD and X-ray diffraction data. Euphorfischerin A showed cytotoxicity against the human cancer cell lines HeLa, H460 and Namalwa with IC50 values of 4.6, 11.5 and 16.4 µM, respectively, while euphorfischerin B gave comparable IC50 values of 9.5, 17.4 and 13.3 µM against the three cancer cell lines, respectively.

Ganorbifates A and B from Ganoderma orbiforme, determined by DFT calculations of NMR data and ECD spectra.

Ganorbifate A featuring an unprecedented 6/6/6/5/5 pentacyclic system, and ganorbifate B with an unusual 6/4/6/5/8/5 ring system were isolated from the fruiting body of Ganoderma orbiforme. Their structures were established using extensive spectroscopic analysis, including DFT calculations of NMR data and ECD spectra.

Triterpenoid saponins from the roots of Psammosilene tunicoides.

Seven oleanane-type triterpenoid saponins, tunicosaponins B-D (1-3), F-I (4-7), along with eight known triterpenoid saponins (8-15), were isolated from the roots of Psammosilene tunicoides. The structures of compounds 1-7 were determined by comprehensive spectroscopic analysis, including 1D and 2D NMR techniques, mass spectrometry and chemical methods. Triterpene glycosides have been considered as major active constituents of P. tunicoides. This work provides a more complete insight into the saponin constituents of P. tunicoides.

Diversity Modification and Structure-Activity Relationships of Two Natural Products 1ß-hydroxy Alantolactone and Ivangustin as Potent Cytotoxic Agents.

Sesquiterpene lactones (STLs) are a class of plant secondary metabolites widely found in nature with potent antitumor activities. In this work, two isolated STLs 1ß-hydroxy alantolactone (1) and ivangustin (2) were derivatized through diversity-oriented strategy, and in vitro cytotoxic activity assessments were conducted against six cell lines including HeLa, PC-3, HEp-2, HepG2, CHO and HUVEC. The cytotoxic structure-activity relationship showed that the double bond between C5 and C6 was beneficial to improve activity; C1-OH oxidized derivatives showed a slight stronger activity, comparable to the positive drug etoposide (VP-16). Yet, C1-OH esterified derivatives decreased the potency which were different from those of 1-O-acetylbritannilactone (ABL) reported previously by us, and C13-methylene reductive and spiro derivatives resulted in almost complete ablation of cytotoxic activity. Mechanistic basis of cytotoxicity of the representative compound 1i was assayed to relate with apoptosis and cell cycle arrest. Furthermore, 1i inhibited TNF-α-induced canonical NF-κB signaling in PC-3 cells. Molecular modeling studies exhibited additional hydrogen bond interaction between 1i and the residue Lys37 of p65, indicating that 1i could form covalent protein adducts with Cys38 on p65.

Picrotoxane Sesquiterpene Glycosides and a Coumarin Derivative from Coriaria nepalensis and Their Neurotrophic Activity.

Two picrotoxane sesquiterpene lactone glycosides, nepalactones A (1) and B (2), and one new coumarin, nepalarin (3), were isolated from the root barks of the poisonous plant Coriarianepalensis. Their structures were elucidated via HRESIMS and 1D and 2D NMR spectroscopic analyses, and further verified via transformation methods. In addition, compounds 1-3 and five semisynthetic congeners (1a-e) were assayed for the activity to induce neurite outgrowth in rat pheochromocytoma (PC12) cells. As a result, nepalactone A derivative 1c and nepalarin (3) significantly enhanced nerve growth factor (NGF)-mediated neurite outgrowth in PC12 cells.

Characterization of isobutylhydroxyamides with NGF-potentiating activity from Zanthoxylum bungeanum.

Eight isobutylhydroxyamides, including three new (1-3), qinbunamides A-C, and five known sanshools (4-8), ZP-amide A (4), ZP-amide B (5), ZP-amide E (6), ZP-amide C (7), and ZP-amide D (8), were isolated from the pericarps of cultivated Zanthoxylum bungeanum Maxim, cultivated in Qinling mountain area, Shaanxi, China. The structures of all compounds were determined on the basis of spectroscopic techniques, including 1D and 2D NMR analysis and comparison with previously reported data. Compounds 1 and 2 are the first example of isobutylhydroxyamides containing an ethoxy group, and compound 3 is a rare C11 fatty acid-containing sanshool existing in genus Zanthoxylum. The tested compounds enhanced nerve growth factor (NGF)-mediated neurite outgrowth (neurotrophic activity) in rat pheochromocytoma (PC12) cells, but were inactive in the inhibitory effects on the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and growth of HCT116 cells at concentrations of 50µM.

Soluble epoxide hydrolase inhibitory and anti-inflammatory components from the leaves of Eucommia ulmoides Oliver (duzhong).

Eucommia ulmoides leaves have been used as a functional food and drink in China. The purpose of this study was to identify the bioactive constituents with soluble epoxide hydrolase (sEH) inhibitory activity and anti-inflammatory properties. Twenty-seven known compounds (1-27) were isolated from the leaves of E. ulmoides Oliver, and their structures were identified by NMR and ESIMS analysis; three of these, 2,5-dimethoxy-3-glucopyranosyl cinnamic alcohol (11), foliasalacioside E2 (26), and icariside F2 (27), were obtained from this plant for the first time. Compounds 1-7 exhibited soluble epoxide hydrolase (sEH) inhibitory activity at 100 µM; among them, quercetin (1) and kaempferol (5) displayed potential activities with IC50 values of 22.5 ± 0.9 and 31.3 ± 2.6 µM, respectively, with noncompetitive inhibition mode. Nuclear factor kappa B (NF-κB) inhibitory activity of the isolated compounds was evaluated by the NF-κB liciferase assay in HepG2 cells. Compounds 1, 9, 20, and 27 displayed potent NF-κB inhibitory effects, with IC50 values of 15.14 ± 2.29, 15.23 ± 2.34, 16.88 ± 2.17, and 16.25 ± 2.19 µM, respectively, whereas other compounds showed weak inhibition of NF-κB transcriptional activity ranging from 17.54 to 92.6 µM. A structure-activity relationship of flavonoids 1-9 was also discussed. The results obtained in this work might contribute to the understanding of pharmacological activities of E. ulmoides leaves and further investigation on its potential application values for food and drug.

Antifungal, phytotoxic and toxic metabolites produced by Penicillium purpurogenum.

Nine known metabolites, 6,8,1'-tri-O-methyl averantin (1), 6,8-di-O-methyl averufnin (2), 6,8-di-O-methyl averufanin (3), aversin (4), 1,3-dihydroxy-6,8-dimethoxy-9,10-anthraquinone (5), 6,8-di-O-methylnidurufin (6), 6,8-di-O-methyl versiconol (7), 5-methyoxysterigmatocystin (8) and (S)-ornidazole (9), were isolated from the extracts of Penicillium purpurogenum, and their structures were elucidated by using spectroscopic methods. The brine shrimp toxicity, anti-phytopathogenic and phytotoxic effects of these compounds were evaluated. Among them, compounds 1 and 8 exhibited the strongest toxicity against brine shrimp (Artemia salina), with lethality rates of 100% at a low concentration of 10 µM, comparable to the positive control toosendanin. Compounds 1, 4 and 7 moderately inhibited the growth of Botrytis cinerea. Moreover, 4 displayed moderate antifungal effects on Gibberella saubinettii. In addition, compounds 6, 7 and 9 produced the phytotoxic effects on radish seedlings at 100 µM. This is the first report on the isolation of these metabolites from this organism.

Chemical constituents of Abies delavayi.

Systematic phytochemical investigations on Abies delavayi afforded 110 compounds, including 49 terpenoids, 13 lignans, 20 flavonoids, three coumarins, and 25 other chemical constituents. By detailed analysis of one- and two-dimensional NMR spectroscopic and high-resolution mass spectrometric data, 10 previously unreported compounds were identified: they comprised three sesquiterpenoids, two diterpenoids, one triterpenoid, one monoterpenoid, one flavonoid, and two phenols. These 10 compounds and some previously known ones were subjected to two cytotoxic bioassays against three human tumor cell lines and NO production inhibition on RAW264.7 macrophages, respectively. (25R)-24,25-Dihydroabieslactone had the strongest cytotoxic activity against Colo-205 cells with an IC50 value of 19.0±3.7µg/mL. (+)-T-cadinol, 8,11,13-abietatrien-15-ol-18-yl acetate, 18-acetoxy-13-epi-manool, imperatorin, bergapten, and 5,7-O-dimethyl poriol exhibited weak inhibitory activity against LPS-induced NO production in RAW264.7 macrophages with IC50 values of approximately 50µg/mL.

Semisynthesis and in vitro cytotoxic evaluation of new analogues of 1-O-acetylbritannilactone, a sesquiterpene from Inula britannica.

Semisynthetic analogues of the natural product 1-O-acetylbritannilactone (ABL), a sesquiterpene isolated from the medicinal plant Inula britannica, have been prepared and exhibited significant in vitro cytotoxic activities against four cell lines including three human cancer cell lines (HCT116, HEp-2 and HeLa) and one normal hamster cell line (CHO). Structure-activity relationships indicate that esterification of 6-OH (enhanced lipophilicity) and α-methylene-γ-lactone functionalities play important roles in conferring cytotoxicity. Among the tested compounds, 14 bearing a lauroyl group (12C) at the 6-OH position displayed most potent in vitro cytotoxic activity, with IC50 values between 2.91 and 6.78 µM, comparable to the positive control etoposide (VP-16, IC50 values between 2.13 and 4.79 µM). Moreover, the compound 14 triggered remarkable apoptosis at a low concentration, and induced cell cycle arrest in G2/M phase in HCT116 cells. The biological assays conducted with normal cells (CHO) revealed that all the synthetic compounds are no selective against cancer cell lines tested.

Two novel lignans from Gaultheria yunnanensis.

Two new lignans, 9-salicyl-(+)-isolariciresinol (1) and gaultheroside G (2), together with seven known compounds, were isolated from the ethanolic extract of the whole plant of Gaultheria yunnanensis. Their structures were determined by extensive NMR and MS analyses. Gaultheroside G (2) was found to have an unusual ether linkage between the 2 and 9' positions of aryl-tetralin lignan skeleton. All nine compounds were assayed for inhibitory effects against nitric oxide and pro-inflammatory cytokines TNF-α and IL-6 release in LPS-induced RAW 246.7 macrophages, while no significant activities were observed for the evaluated compounds.

Bioactive metabolites from the mycelia of the basidiomycete Hericium erinaceum.

Seven known compounds, three diketopiperazine alkaloids, 12ß-hydroxyverruculogen TR-2 (1), fumitremorgin C (2) and methylthiogliotoxin (5), two hetero-spirocyclic γ-lactam alkaloids, pseurotin A (3) and FD-838 (4), and cerevisterol (6) and herierin IV (7), were isolated from the mycelia of the basidiomycete Hericium erinaceum and identified by spectroscopic analyses. The antioxidant and antifungal activities of compounds 1-6 were evaluated. The results indicated that compounds 1, 3 and 6 exhibited potential antioxidant activity against DPPH (2, 2-diphenyl-1-picrylhydrazyl) radical with their IC50 data of ca. 12 µM, compared with positive control tertiary butylhydroquinone. In addition, compound 4 significantly inhibited the growth of two plant fungal pathogens Botrytis cinerea and Glomerella cingulata with an minimum inhibitory concentration of 6.25 µM for each, similar to that of the positive fungicide, carbendazim. Compounds 1-5 were isolated from the genus Hericium for the first time.

Bioactive metabolites isolated from Penicillium sp. YY-20, the endophytic fungus from Ginkgo biloba.

Six known metabolites, adenosine (1), methyl ß-D-ribofuranoside (2), adenine (3), 2'-deoxyadenosine (4), 3-methylpiperazine-2,5-dione (5) and 2'-deoxyuridine (6), were isolated from the extracts of the endophytic fungus Penicillium sp. YY-20 isolated from the root of Ginkgo biloba, and their structures were elucidated by spectroscopic methods. The antioxidant and growth-promoting activities of these compounds were first evaluated. The results indicated that compounds 1, 3 and 4 exhibited potential DPPH-scavenging activities compared with positive control. In addition, all the compounds (except 5) stimulated seed germination of Raphanus sativus, Brassica napus and Brassica chinensis but had weak stimulating effect on their root and hypocotyl growth.

Semisynthesis and antifeedant activity of new derivatives of a dihydro-ß-agarofuran from Parnassia wightiana.

Five new derivatives (2-6) were semi-synthesized using compound 1, a dihydro-ß-agarofuran sesquiterpene with C-2 ketone obtained from Parnassia wightiana, as the starting material by acylation, oxidation, reduction, esterification, and amination, respectively. Structures of 2-6 were confirmed by 1D- and 2D-NMR and HR-ESI-MS spectra. In addition, antifeedant activities of these compounds (1-6) were tested against the 3rd-instar larvae of Mythimna separata. Antifeedant effects of compounds 2 and 4 were greater than the parent compound 1 whereas other compounds exhibited low to no feeding deterrent effects against third instar M. separata larvae in lab bioassays. Therefore, our results suggest that acylated and reduced derivatives at C-8 and C-2, respectively, of 1 may improve the antifeeding effect. This preliminary information will be useful in designing new insect control agents against M. separata and other important pests.

Alkaloids from Cephalotaxus lanceolata and their cytotoxicities.

A phytochemical investigation of the branches and leaves of Cephalotaxus lanceolata resulted in the isolation of three new cephalotaxus alkaloids, cephalancetines A, B, and D (1, 2, and 4, resp.), together with ten known alkaloids, 3 and 5-13. The structures of the alkaloids were elucidated on the basis of spectroscopic analyses, including 1D- and 2D-NMR, and HR-ESI-MS, and single-crystal X-ray diffraction. All isolated compounds were tested for their cytotoxicities against four human tumor cell lines, A549, HCT116, SK-BR-3, and HepG2. Compounds 12 and 13 showed remarkable activities against A549, HCT116, and HepG2 cell lines.

Absolute configuration of fusarone, a new azaphilone from the endophytic fungus Fusarium sp. isolated from Melia azedarach, and of related azaphilones.

A new azaphilone derivative, named fusarone (1), has been isolated from the ethyl acetate soluble extract of the fermentation broth of an endophytic fungus, Fusarium sp. LN-12, isolated from the leaves of Melia azedarach Linn. The structure of the new compound was established on the basis of extensive spectroscopic analysis, including 1D-NMR and 2D-NMR ((1) H-(1)H COSY, TOCSY, HSQC, HMBC, and NOESY) experiments. The absolute configurations of fusarone (1) and of a second related azaphilone were determined by means of electronic circular dichroism spectroscopy and optical rotation calculations.