Stelleranoids A-M, guaiane-type sesquiterpenoids based on [5,7] bicyclic system from Stellera chamaejasme and their cytotoxic activity

Osthole Activates the Cholinergic Anti-Inflammatory Pathway via α7nAChR Upregulation to Alleviate Inflammatory Responses

Osthole (also known as Osthol) is the main anti-inflammatory coumarin found in Cnidium monnieri and severs as the exclusive quality-controlled component according the Chinese Pharmacopoeia. However, its underlying anti-inflammatory mechanism remains unknown. In this study, we demonstrated that Osthole treatment significantly inhibited the generation of TNF-α, but not IL-6 in the classical LPS-stimulated RAW264.7 macrophage model. In addition, LPS induced the activation of both MAPK and NF-κB signalling pathways, of which the former was dose-dependently restrained by Osthole via suppressing the phosphorylation of JNK and P38 proteins, while the phosphorylation of IκB and P65 proteins remained unaffected. Interestingly, Osthole dose-dependently up-regulated the expression of the key cholinergic anti-inflammatory pathway regulator α7nAChR, and the TNF-α inhibition effect of Osthole was also significantly alleviated by the treatment of α7nAChR antagonist methylbetaine. These results demonstrate that Osthole may regulate TNF-α by promoting the expression of α7nAChR, thereby activate the vagus nerve-dependent cholinergic anti-inflammatory pathway.

Glaucatotones A-I: Guaiane-type sesquiterpenoids from the roots of Lindera glauca with anti-inflammatory activity

Glaucatotones A - I, nine new guaiane-type sesquiterpenoids, along with two reported compounds, namely (1β,5β)-1-hydroxyguaia-4(15),11(13)-dieno-12,5-lactone (10) and pseudoguaianelactone C (11), were isolated from the roots of Lindera glauca. The structures and absolute configurations of these compounds were elucidated by extensive spectroscopic analyses, single-crystal X-ray diffraction, and comparison of experimental and calculated electronic circular dichroism (ECD) data. Structurally, glaucatotone A (1) is characterized as a dihomosesquiterpenoid with an unprecedented 5/5/7/6 ring system. A pair of enantiomers, (±)-glaucatotone B (2a/2b), represent the first rearranged norsesquiterpenoid with a (cyclopentylmethyl)cyclohexane skeleton. 3 is defined as a dinorsesquiterpenoid possessing a 5/7/5 ring system. 4-6 are three guaiane-type norsesquiterpenoids. In vitro bioactivity, 2a selectively inhibited Bcap-37 with IC50 value of 5.60 μM, and 9 selectively inhibited Du-145 with IC50 value of 5.52 μM. The anti-inflammatory activity of 1-9 were tested, and of these compounds, 1, 2a, 2b and 7 exhibited potent inhibitory effects.

Antimicrobial sesquiterpenes from the cultured mycobiont Diorygma pruinosum against methicillin-resistant Staphylococcus aureus isolated from Vietnamese street foods

Traditionally, lichen has been used for many purposes, but there remains a lack of understanding regarding the chemical composition and antimicrobial characteristics of Diorygma pruinosum, a lichen native to Vietnam. In this study, four sesquiterpenes, diorygmones B-E (1-4), one phenolic compound, 3,5-dihydroxy-4-methoxybenzoic acid (5), and one sterol, β-sitosterol (6), were isolated and structurally elucidated from the cultured mycobiont of the lichen Diorygma pruinosum. Additionally, two compounds, stictic acid (7) and norstictic acid (8), were also isolated from the lichen D. pruinosum. Compounds 2-4 were new compounds. Their chemical structures were established using comprehensive spectroscopic data, and the absolute configurations were confirmed through the analysis of NOESY and electronic circular dichroism (ECD). Moreover, Staphylococcus aureus, a Gram-positive bacterium, has been responsible for various infections, including food poisoning. Herein, we identified and isolated 13 strains of S. aureus from street food sources. Among these strains, one was identified as a multidrug-resistant variant, designated as SAX15, and was subsequently used for further antimicrobial testing. Compounds 1-3 produced zones of inhibition against S. aureus SAX15 (each 5 mm) in comparison to commercial drugs such as penicillin, ciprofloxacin, gentamicin, cefoxitin, and clarithromycin, which displayed inhibitory zones of 7, 5, 10, 9.7, and 7 mm, respectively.

Terpenoids from the Roots of Stellera chamaejasme (L.) and Their Bioactivities

An undescribed diterpene, stellerterpenoid A (1), and two undescribed sesquiterpenoids, stellerterpenoids B and C (2-3), together with six known compounds, prostratin (4) stelleraguaianone B (5), chamaejasnoid A (6), auranticanol L (7), wikstronone C (8), and oleodaphnone (9), were isolated from the roots of Stellera chamaejasme L. Their structures were elucidated by extensive spectroscopic data (1D, 2D NMR, IR, UV, and HR-ESI-MS). The absolute configuration of 1-3 was elucidated based on ECD calculation. Among them, stellerterpenoid A was a rare 13, 14-seco nortigliane diterpenoid and stellerterpenoid B was a guaiacane-type sesquiterpenoid with an unusual 1, 2-diketone moiety. The known stelleraguaianone B (5) exhibited moderate activity for suppressing NO production in lipopolysaccharide (LPS)-treated RAW 264.7 macrophages cells with an IC50 value of 24.76 ± 0.4 μM. None of the compounds showed anti-influenza virus or anti-tumor activity in vitro.

Anti-inflammatory lanostane triterpenoids with rearranged spirobi[indene] scaffold and their biogenetically related analogues from Euphorbia maculata

Phytochemical investigations on the ethanol extract of the whole plant of Euphorbia maculata Linn. Resulted in the identification of 16 lanostane-related triterpenoids, including 11 undescribed ones, namely spiromaculatols A-C (1-3) and euphomaculatoids A-H (4-11). The structural determinations of the previously undescribed ones (1-11) were elucidated based on the interpretation of comprehensive spectroscopic data, quantum chemical calculation, as well as X-ray crystallographic experiments. Spiromaculatols A-C (1-3) possess a rare spirobi [indane] skeleton, which was biosynthetically derived from the 7 (8 → 9)-abeo bond migration of lanostane precursors. The biological activity of compounds 1-3, 5, 7, and 12-13 displayed inhibitory effect on the release of NO in an LPS-activated RAW264.7 cells model. Molecular mechanism study indicated that the most potent spiromaculatol C (3) can reduce the nuclear translocation of NF-κB p65 and decrease the transcriptional expressions of its downstream pro-inflammatory mediators.

Discovering the Mechanisms of Oleodaphnone as a Potential HIV Latency-Reversing Agent by Transcriptome Profiling

Latent HIV is a key factor that makes AIDS difficult to cure. Highly effective and specific latent HIV activators can effectively activate latent HIV, and then combined with antiretroviral therapy to achieve a functional cure of AIDS. Here, four sesquiterpenes (1-4) including a new one (1), five flavonoids (5-9) including three biflavonoid structures, and two lignans (10 and 11) were obtained from the roots of Wikstroemia chamaedaphne. Their structures were elucidated through comprehensive spectroscopic analyses. The absolute configuration of 1 was determined by experimental electronic circular dichroism. NH2 cell model was used to test the activity of these 11 compounds in activating latent HIV. Oleodaphnone (2) showed the latent HIV activation effect as well as the positive drug prostratin, and the activation effect was time- and concentration-dependent. Based on transcriptome analysis, the underlying mechanism was that oleodaphnone regulated the TNF, C-type lectin receptor, NF-κB, IL-17, MAPK, NOD-like receptor, JAK-Stat, FoxO, and Toll-like receptor signaling pathways. This study provides the basis for the potential development of oleodaphnone as an effective HIV latency-reversing agent.

Diversity of sesquiterpenoids from Stellera chamaejasme with neuroprotective effects

Chromatographic fractionation of the 95% EtOH extract of the roots of Stellera chamaejasme yielded 20 sesquiterpenoids of four different types, guaiane-, carotane-, sesquicarane-, and alpiniane-types. Among them, sesquistrachanoids A-F were previously undescribed ones, whose structures including absolute configurations were elucidated by spectroscopic methods, the Mo₂(OAc)₄-induced ECD experiment, and analysis of experimental and calculated 1D NMR and ECD data. Sesquistrachanoid A is a 2,3-seco-guaiane-type sesquiterpenoid with a α-pyrone core and sesquistrachanoid B is the first example of 8,9-seco-guaiane-type sesquiterpenoid featured with an 1,8-δ-lactone core. Sesquistrachanoid C is a guaiane sesquiterpenoid characterized by a peroxide bridge between C-8 and C-10. All sesquiterpenoids were evaluated for their neuroprotective effects on cell damage induced by sodium nitroprusside in PC-12 cells. The bioassay results showed that six compounds at 10 μM could restore the cell viability, being comparable to that of the positive control edaravone. The mechanistic study on the most pronounced activity compound, stelleraguaianone B, demonstrated that it played a neuroprotective role by promoting the mRNA expression of antioxidant enzymes to reduce oxidative stress.

New Guaiane-Type Sesquiterpenoids Biscogniauxiaols A-G with Anti-Fungal and Anti-Inflammatory Activities from the Endophytic Fungus Biscogniauxia Petrensis

Seven undescribed guaiane-type sesquiterpenoids named biscogniauxiaols A-G (1-7) were isolated from the endophytic fungus Biscogniauxia petrensis on Dendrobium orchids. Their structures were determined by extensive spectroscopic analyses, electronic circular dichroism (EC) and specific rotation (SR) calculations. Compound 1 represented a new family of guaiane-type sesquiterpenoids featuring an unprecedented [5/6/6/7] tetracyclic system. A plausible biosynthetic pathway for compounds 1-7 was proposed. The anti-fungal, anti-inflammatory and multidrug resistance reversal activities of the isolates were evaluated. Compounds 1, 2 and 7 exhibited potent inhibitory activities against Candida albicans with MIC values ranging from 1.60 to 6.30 μM, and suppressed nitric oxide (NO) production with IC50 ranging from 4.60 to 20.00 μM. Additionally, all compounds (100 μg/mL) enhanced the cytotoxicity of cisplatin in cisplatin-resistant non-small cell lung cancer cells (A549/DDP). This study opened up a new source for obtaining bioactive guaiane-type sesquiterpenoids and compounds 1, 2, and 7 were promising for further optimization as multifunctional inhibitors for anti-fungal (C. albicans) and anti-inflammatory purposes.

Targeted isolation of diterpenoids and sesquiterpenoids from Daphne gemmata E. Pritz. ex Diels using molecular networking together with network annotation propagation and MS2LDA

Investigation of the whole plant of Daphne gemmata E. Pritz. ex Diels (Thymelaeaceae) using molecular networking coupled to Network Annotation Propagation (NAP) and unsupervised substructure annotation (MS2LDA) led to the discovery of five tigliane diterpenoids, 14 guaiane sesquiterpenoids, one rhamnofolane diterpenoid and three carotene sesquiterpenoids. The structures of the eight undescribed compounds, daphnorbol A and daphnegemmatoids A-G, were characterized by detailed spectroscopic analyses, NMR and ECD calculations, application of Snatzke's method and single-crystal X-ray diffraction analysis. All isolated compounds were evaluated for their cytotoxic activities against HepG2, A549, and MCF-7 cells by MTT assay. Daphnorbol A exhibited significant cytotoxic activity against HepG2 and A549 cells with IC50 values of 4.06 μM and 6.35 μM, respectively. Prostratin showed potent cytotoxic activity against HepG2 and A549 cells with IC50 values of 6.06 μM and 5.45 μM, respectively. Further Hoechst 33,258 and AO-EB staining assays indicated that daphnorbol A and prostratin could induce apoptosis in HepG2 and A549 cells.

Sesquiterpenoids from Ixeris sonchifolia and their neuroprotective activities

The phytochemical investigation of the methanol extract of Ixeris sonchifolia led to the isolation and identification of nine analogs, including one new guaiane-type sesquiterpenoid, named ixerinoid A (1). The structure of 1 was determined by extensive analysis of the 1 D and 2 D nuclear magnetic resonance spectroscopic data, as well as quantum chemical calculations. Additionally, all the isolates were tested for their neuroprotective activity using the oxygen-glucose deprivation/reperfusion-induced SH-SY5Y cell injury model. Compounds 3, 5, 6, 8, and 9 displayed remarkable protective effects at concentrations of 1, 5, and 10 μM, respectively.

Brujavanoids A-U, structurally diverse apotirucallane-type triterpenoids from Brucea javanica and their anti-inflammatory effects

Extensive phytochemical investigation on the methanol extract of the inflorescences, twigs, and leaves of Brucea javanica led to the isolation and identification of 27 triterpenoids, including 21 previously undescribed ones, named brujavanoids A-U (1-21). Their structures were determined based on comprehensive spectroscopic analysis and single-crystal X-ray diffraction. Of these compounds, brujavanoid A (1) represents the first apotirucallane-type triterpenoid with a novel 19(10 → 9)abeo motif, and brujavanoids B and C (2-3) are the first apotirucallane-type triterpenoids with a rarely occurring 14-hydorxy-15,16-epoxy fragment. All the isolates were evaluated for their anti-inflammatory effect in an LPS-activated RAW264.7 cells model. Furthermore, the most active one, brujavanoid E (5), can suppress the transcriptional expression of typical pro-inflammatory mediators and inhibit the nuclear translocation of NF-κB p65 in the LPS- activated RAW264.7 cells.

Rare Carbon-Bridged Citrinin Dimers from the Starfish-Derived Symbiotic Fungus Penicillium sp. GGF16-1-2

Four novel, rare carbon-bridged citrinin dimers, namely dicitrinones G–J (1–4), and five known analogs (5–9) were isolated from the starfish-derived fungus Penicillium sp. GGF 16-1-2. Their structures were elucidated by extensive spectroscopic analysis and quantum chemical calculations. Compounds 1–9 exhibited strong antifungal activities against Colletotrichum gloeosporioides with LD₅₀ values from 0.61 μg/mL to 16.14 μg/mL. Meanwhile, all compounds were evaluated for their cytotoxic activities against human pancreatic cancer BXPC-3 and PANC-1 cell lines; as a result, compound 1 showed more significant cytotoxicities than the positive control against both cell lines. In addition, based on the analyses of the protein-protein interaction (PPI) network and Western blot, 1 could induce apoptosis by activating caspase 3 proteins (CASP3).

Jatrophane Diterpenoids with Kv1.3 Ion Channel Inhibitory Effects from Euphorbia helioscopia

Chemical investigation of bioactive components from the whole plant of Euphorbia helioscopia resulted in the isolation and identification of 17 new jatrophane diterpenoids, namely, heliojatrone D (1) and helioscopids A-P (2-17), along with 11 known analogues (18-28). The structural elucidation of the new diterpenoids was achieved by the comprehensive analysis of HRESIMS, NMR, and X-ray crystallographic data, as well as using electronic circular dichroism. Structurally, heliojatone D (1) is the fourth natural diterpenoid with a rare bicyclo[8.3.0]tridecane skeleton. The inhibitory effect of the isolated diterpenoids against Kv1.3 ion channels was evaluated in a human embryonic kidney 293 cell model transfected with plasmid encoding Kv1.3, resulting in the identification of a series of potent Kv1.3 ion channel inhibitors, with the most active ones (2 and 15) showing IC₅₀ values of 0.9 μM.

Hyperbeanone A, a 5,6-seco-spirocyclic polycyclic polyprenylated acylphloroglucinol derivative with an unprecedented skeleton from Hypericum beanii

Hyperbeanone A (1), a novel 5,6-seco-polycyclic PPAP derivative characterized by an undescribed benz[f]indene-1,9(4H)-dione ring system fused to a tricyclic γ-lactone unit via a ketone carbonyl, was isolated from the aerial parts of Hypericum beanii.