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 (1ß,5ß)-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.

Novel drimane-type sesquiterpenoids and nucleosides from the Helicoma septoconstrictum suppress the growth of ovarian cancer cells.

Four new drimane-type sesquiterpenoids and two new nucleoside derivatives (1-6), were isolated from the fungus Helicoma septoconstrictum. Their structures were determined based on the combination of the analysis of their HR-ESI-MS, NMR, ECD calculations data and acid hydrolysis. All the isolated compounds were detected for their bio-activities against MDA-MB-231, A549/DDP, A2780 and HepG2 cell lines. Helicoside C (4) exhibited superior cytotoxicity against the A2780 cell line with IC50 7.5 ± 1.5 µM. The analysis of reactive oxygen species (ROS) revealed that Helicoside C induced an increase in intracellular ROS. Furthermore, the flow cytometry and mitochondrial membrane potential (MMP) analyses unveiled that Helicoside C mediated mitochondrial-dependent apoptosis in A2780 cells. The western blotting test showed that Helicoside C could suppress the STAT3's phosphorylation. These findings offered crucial support for development of H. septoconstrictum and highlighted the potential application of drimane-type sesquiterpenoids in pharmaceuticals.

Sesquiterpenoids from Carpesium abrotanoides and their anti-inflammatory activity both in vitro and in vivo.

Twenty-nine sesquiterpenoids, including pseudoguaiane-type (1-11), eudesmane-type (12-23), and carabrane-type (24-29), have been identified from the plant Carpesium abrotanoides. Of them, compounds 1-4, 12-15, and 24-27, namely carpabrotins A-L, are twelve previously undescribed ones. Compound 3 possessed a pseudoguaiane backbone with a rearrangement modification at C-11, C-12 and C-13, while compound 4 suffered a carbon bond break between the C-4 and C-5 to form a rare 4,5-seco-pseudoguaiane lactone. Compounds 1-3, 5, 13-16 and 25-27 exhibited anti-inflammatory activity by inhibiting NO production in LPS-induced RAW264.7 macrophages with IC50 values less than 40 µM, while compounds 1, 2, 5, 13, 14, 16, and 25-27 showed significant inhibitory activity comparable to that of dexamethasone. The anti-atopic dermatitis (AD) effects of compounds 5 and 16 were tested according to 2,4-dinitrochlorobenzene (DNCB)-induced AD-like skin lesions in KM mice, and the results revealed that the major products 5 and 16 improved the histological features of AD-like skin lesions and mast cell infiltration in mice. This study suggested that sesquiterpenoids in C. abrotanoides should play a key role in its anti-inflammatory use.

The discovery of a new potent FXR agonist based on natural product screening.

FXR agonistic activity screening was conducted based on natural product resources containing 38 structurally diverse sesquiterpenoids isolated from Xylopia vielana. Among them, 34 undescribed sesquiterpenoids with 5 different skeleton types were first characterized by HRESIMS, NMR data, ECD calculations and X-ray crystallographic analysis. High-content screening for FXR agonistic activity of these compounds demonstrated that 13 compounds could activate FXR. Then molecular docking results suggested that hydrogen bonding and hydrophobic interactions might contribute to the main interaction of active compounds with FXR. The preliminary structure-activity relationships (SARs) of those isolates were also discussed. The most potent compound 27 significantly elevated the transcriptional activity of the FXR target gene BSEP promoter (EC50 = 14.26 µM) by a dual-luciferase reporter assay. Western blotting indicated that compound 27 activated the FXR-associated pathway, thereby upregulating SHP and BSEP expression, and downregulating CYP7A1 and NTCP expression. We further revealed that FXR was the target protein of compound 27 through diverse target validation methods, including CETSA, SIP, and DARTS under the intervention of temperature, organic reagents and protease. Pharmacological in vivo experiments showed that compound 27 effectively ameliorated α-naphthyl isothiocyanate (ANIT)-induced cholestasis in mice, as evidenced by the ameliorative histopathology of the liver and the decrease in biochemical markers: alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), total bilirubin (TBIL), direct bilirubin (DBIL), and total bile acid (TBA). This work showed a practical strategy for the discovery of new FXR agonists from natural products and provided potential insights for sesquiterpenoids as FXR agonist lead compounds.

Discovery of potential components characteristic by conjugated enone from the branches and leaves of Croton lauioides with anti-neuroinflammatory activity via regulating the NF-κB pathway.

In this study, the chemical composition and pharmacological activity of Croton lauioides were investigated for the first time. The bioactive and HPLC-UV guided isolation led to the discovery of twenty-three conjugated enone-type components (1-23), including nine previously unknown sesquiterpenoid derivatives (1-4, 9-10, 12-14). Notably, compounds 1 and 12 are epoxides containing an endoperoxide bridge (1) or a unique dioxaspiro core (12), respectively. Compounds 2-7 are non-benzenoid aromatics featuring a tropone function, while 9-11 possess a rare rearranged scaffold with tropone shift into benzene. Extensive characterization was performed using NMR spectra, HRESIMS data, and electronic circular dichroism (ECD) calculations. Furthermore, we evaluated the bioactivities of all isolated compounds against neuroinflammation in LPS-stimulated BV-2 microglial cells. Remarkably, most sesquiterpenoid derivatives exhibited significant NO inhibit activities, and compound 5 showed the most potent effect with an IC50 value of 0.14 ± 0.04 µM. Structure-activity relationship (SAR) analysis revealed that sesquiterpenoids modified with endocyclic enone conjugation may serve as a key pharmacophore for NO inhibition, particularly involving aromatic tropone moiety. The qPCR and Western blot results demonstrated that 5 exerted an inhibitory effect on the mRNA levels of iNOS, TNF-α and COX-2 in a time-dependent manner, as well as suppressed the protein expression of iNOS, TNF-α, COX-2. In mechanism, 5 could prevented activation of NF-κB pathway by suppressing phosphorylation of p65 and IκB-α. These findings revealed C. lauioides might be a promising resource for drug candidate development targeting neuroinflammation.

Discovery of sesquiterpenoids from an actinomycete Crossiella cryophila through genome mining and heterologous expression.

Genome mining of the Actinomycete Crossiella cryophila facilitated the discovery of a minimal terpenoid biosynthetic gene cluster of cry consisting of a class I terpene cyclase CryA and a CYP450 monooxygenase CryB. Heterologous expression of cry allowed the isolation and characterization of two new sesquiterpenoids, ent-viridiflorol (1) and cryophilain (2). Notably, cryophilain (2) possesses a 5/7/3-fused tricyclic skeleton bearing a distinctive bridgehead hydroxy group. The combined in vivo and in vitro experiments revealed that CryA, the first ent-viridiflorol terpene cyclase, catalyzes farnesyl diphosphate to form the 5/7/3 sesquiterpene core scaffold and P450 CryB serves as a tailoring enzyme responsible for installing a hydroxy group at the bridgehead carbon.

Discovery of sesquiterpenoids from the roots of Chloranthus henryi Hemsl. var. hupehensis (Pamp.) K. F. Wu and their anti-inflammatory activity by IKBα/NF-κB p65 signaling pathway suppression.

Phytochemical analysis of Chloranthus henryi var. hupehensis roots led to the identification of a new eudesmane sesquiterpenoid dimer, 18 new sesquiterpenoids, and three known sesquiterpenoids. Among the isolates, 1 was a rare sesquiterpenoid dimer that is assembled by a unique oxygen bridge (C11-O-C8') of two highly rearranged eudesmane-type sesquiterpenes with the undescribed C16 carbon framework. (+)-2 and (-)-2 were a pair of new skeleton dinorsesquiterpenoids with a remarkable 6/6/5 tricyclic ring framework including one γ-lactone ring and the bicyclo[3.3.1]nonane core. Their structures were elucidated using spectroscopic data, single-crystal X-ray diffraction analysis, and quantum chemical computations. In the LPS-induced BV-2 microglial cell model, 17 suppressed IL-1ß and TNF-α expression with EC50 values of 6.81 and 2.76 µM, respectively, indicating its excellent efficacy in inhibiting inflammatory factors production in a dose dependent manner and without cytotoxicity. In subsequent mechanism studies, compounds 3, 16, and 17 could reduce IL-1ß and TNF-α production by inhibiting IKBα/p65 pathway activation.

Sesquiterpenoids from the roots of Lindera glauca and their cytotoxicity activities.

The chemical investigation of the roots of Lindera glauca guided the isolation and identification of 3 new sesquiterpenoids, namely glaucatotones J-L (1-3), and one known congener, (1ß,5ß)-1-hydroxyguaia-4(15),11(13)-dieno-12,5-lactone (4). The structures of new compounds were established based on comprehensive spectrographic methods, mainly including 1D & 2D NMR and HRESIMS analyses, and the absolute configurations were further confirmed by the comparison of experimental and calculated electronic circular dichroism. The cytotoxicity activities of isolates were evaluated, and the results showed that they have moderate cytotoxic activities.

Lemneolemnanes A-D, Four Uncommon Sesquiterpenoids from the Soft Coral Lemnalia sp.

Four undescribed sesquiterpenoids, lemneolemnanes A-D (1-4), have been isolated from the marine soft coral Lemnalia sp. The absolute configurations of the stereogenic carbons of 1-4 were determined by single-crystal X-ray crystallographic analysis. Compounds 1 and 2 are epimers at C-3 and have an unusual skeleton with a formyl group on C-6. Compound 3 possesses an uncommonly rearranged carbon skeleton, while 4 has a 6/5/5 tricyclic system. Compound 1 showed significant anti-Alzheimer's disease (AD) activity in a humanized Caenorhabditis elegans AD pathological model.

Biotransformation of Glaucic Acid Isolated from the Root of Lindera glauca by the Endophytic Fungi Penicillium Chrysogenum SHJ-07.

Glaucic acid isolated from the root of Lindera glauca, was investigated by the biotransformation methods via the endophytic fungi, resulting in the production of five new glausesquiterpenes A‒E (1‒5), along with a known analogue 6. Their structures were elucidated based on spectroscopic methods and electronic circular dichroism (ECD) calculations. In the bioassays, glausesquiterpene A (1) showed good inhibitory activity of NO production in LPS-activated RAW 264.7 macrophages with an IC50 value of 20.1 µM than positive control (Indomethacin, IC50 24.1 µM). Further in vitro studies demonstrated that glausesquiterpene A significantly suppressed the protein expression of iNOS and COX-2 at the concentration of 25.0 µM.

New sesquiterpenoids from Biscogniauxia sp.

Five new sesquiterpenoids, including a campherenane-type (1), a bergamotane-type (2), a drimane-type (3), and two bisabolane-type (5-6) sesquiterpenoids have been isolated from Biscogniauxia sp. 71-10-1-1. Their structures were determined by spectroscopic analyses, quantum chemical ECD calculations,13C chemical shifts calculations, and X-ray crystallography. This is the first report of campherenane-type and drimane-type sesquiterpenoids from Biscogniauxia. Furthermore, the anti-inflammatory assays of all compounds are evaluated, and the results showed that compounds 3 and 7 exhibited the effects against the production of the pro-inflammatory cytokine TNF-α.

Sesquiterpenoids from cigar tobacco leaves.

Phytochemical investigation on cigar tobacco leaves led to four unknown sesquiterpenoids as well as nine reported ones. Among of them, 3-acetoxy-ß-damascone was first found in tobacco leaves. All the structures were elucidated by intensive spectroscopic analyses and X-ray diffraction. The relationship between the newly isolates and known ones was tried to describe.

Target isolation of diverse sesquiterpenoid from the stems of Daphne genkwa based on molecular networking.

Guiding by LC-MS/MS analysis and the Global Natural Products Social (GNPS) Molecular Networking, three undescribed sesquiterpenoids, stedapgens A-C, and two known analogues were discovered in the barks of Daphne genkwa Sieb. et Zucc. The structures were determined by analysis of their spectroscopic data and quantum-chemical calculations. All the isolated novel compounds were tested for their acetylcholinesterase inhibitory activities with IC50 = 0.754 ± 0.059, 0.696 ± 0.026, and 0.337 ± 0.023 µg/ml. Among them, stedapgen A displayed promising inhibitory activities against AChE, and the binding sites were predicted by molecular docking.

Chemical Investigation on the Volatile Part of the CO2 Supercritical Fluid Extract of Infected Aquilaria sinensis (Chinese Agarwood).

This work is focused on the characterization of the composition of a CO2 supercritical fluid extract of Aquilaria sinensis (Chinese agarwood) collected in the Dongguan area (China) and infected by mechanical methods. The constituents of this extract were analyzed by gas chromatography-mass spectrometry (GC-MS) and quantified accurately by gas chromatography with a flame ionization detector (GC-FID), using an internal reference and predicted response factors. Since a significant number of components of this extract remained non-identified after the initial GC-MS analysis of the whole extract, its fractionation by chromatography on silica gel helped to characterize several additional constituents by isolation and structural analysis by NMR spectroscopy. The main components are the classical agarwood chromones (Flindersia chromone and its mono-, di-, and trimethoxylated analogues (respectively, 11.01% and 0.11-4.02%) along with sesquiterpenic constituents typically found in agarwood essential oils, like baimuxinal (1.90%) and kusunol (1.24%), as well as less common selinane dialdehydes (1.58-2.27%) recently described in the literature. Moreover, the structure and stereochemistry of a new sesquiterpenic alcohol, 14ß,15ß-dimethyl-7αH-eremophila-9,11-dien-8ß-ol (0.67%), was determined unambiguously by the combination of structural analysis (NMR, MS), hemisynthesis, and total synthesis, leading to dihydrokaranone and a neopetasane epimer.

Three New Ionone Glycosides from Rhododendron capitatum Maxim.

Six ionone glycosides (1-3 and 5-7), including three new ones, named capitsesqsides A-C (1-3), together with an eudesmane sesquiterpenoid glycoside (4) and three known triterpenoid saponins (8-10) were isolated from Rhododendron capitatum. The structures of these compounds were determined by extensive spectroscopic techniques (MS, UV, 1D-NMR, and 2D-NMR) and comparison with data reported in the literature. The absolute configurations were determined by comparison of the experimental and theoretically calculated ECD curves and LC-MS analyses after acid hydrolysis and derivatization. The anti-inflammatory activities of these compounds were evaluated in the LPS-induced RAW264.7 cells. Molecular docking demonstrated that 2 has a favorable affinity for NLRP3 and iNOS.

Solid-Phase Microextraction/Gas Chromatography-Time-of-Flight Mass Spectrometry Approach Combined with Network Pharmacology Analysis to Evaluate the Quality of Agarwood from Different Regions against Anxiety Disorder.

Agarwood (Aquilaria malaccensis Lam.) is a resinous material from different geographical locations. The current evaluation of agarwood quality is usually based on its physical properties and chemical compounds, yet only a few studies have linked agarwood quality with its anxiolytic effect, as indicated by characteristic compounds. In this study, using solid-phase microextraction/gas chromatography-time-of-flight mass spectrometry (SPME/GC-TOFMS) and multivariate analysis, we found 116 significantly different compounds in agarwood samples from four locations in Southeast Asia with regard to their quality. Brunei and Nha Trang agarwood had abundant sesquiterpenoids, exhibiting notable pharmacological efficacy in relieving anxiety. Malaysian and Irian agarwood had abundant alcohols and aldehydes, qualifying them as high-quality spices. Compound-target-disease network and pathway enrichment analysis were further employed to predict 79 gene targets and 20 pathways associated with the anxiolytic effects based on the 62 sesquiterpenoids. The correlated relationships among the sesquiterpenoids and targets suggest that agarwood treats anxiety via multiple compounds acting on multiple targets. Varying levels of sesquiterpenes across agarwood groups might lead to differences in the anxiolytic effects via signaling pathways, such as neurotransmitter- and hormone-regulated pathways. Our study originally evaluates agarwood quality and its anxiolytic effect by linking the characteristic compounds to potential gene targets and pathways.

Individual lipid transfer proteins from Tanacetum parthenium show different specificity for extracellular accumulation of sesquiterpenes.

KEY MESSAGE: A highly specialized function for individual LTPs for different products from the same terpenoid biosynthesis pathway is described and the function of an LTP GPI anchor is studied. Sequiterpenes produced in glandular trichomes of the medicinal plant Tanacetum parthenium (feverfew) accumulate in the subcuticular extracellular space. Transport of these compounds over the plasma membrane is presumably by specialized membrane transporters, but it is still not clear how these hydrophobic compounds are subsequently transported over the hydrophilic cell wall. Here we identified eight so-called non-specific Lipid transfer proteins (nsLTPs) genes that are expressed in feverfew trichomes. A putative function of these eight nsLTPs in transport of the lipophilic sesquiterpene lactones produced in feverfew trichomes, was tested in an in-planta transport assay using transient expression in Nicotiana benthamiana. Of eight feverfew nsLTP candidate genes analyzed, two (TpLTP1 and TpLTP2) can specifically improve extracellular accumulation of the sesquiterpene costunolide, while one nsLTP (TpLTP3) shows high specificity towards export of parthenolide. The specificity of the nsLTPs was also tested in an assay that test for the exclusion capacity of the nsLTP for influx of extracellular substrates. In such assay, TpLTP3 was identified as most effective in blocking influx of both costunolide and parthenolide, when these substrates are infiltrated into the apoplast. The TpLTP3 is special in having a GPI-anchor domain, which is essential for the export activity of TpLTP3. However, addition of the TpLTP3 GPI-anchor domain to TpLTP1 resulted in loss of TpLTP1 export activity. These novel export and exclusion assays thus provide new means to test functionality of plant nsLTPs.

CYPArm2 is a CYP450 Monooxygenase with Protoilludene 13-Hydroxylase Activity Involved in the Biosynthesis of Armillyl Orsellinate-Type Sesquiterpenoids.

The melleolides are a family of structurally and functionally diverse sesquiterpenoids with potential applications as fungicides, antimicrobials, and cancer therapeutics. The initial and terminal steps of the biosynthesis pathway in Armillaria spp. have been characterized, but the intermediate steps are unclear. Biosynthetic gene clusters in A. mellea and A. gallica were shown to encode a terpene cyclase, a polyketide synthase, and four CYP450 monooxygenases. We have characterized CYPArm3, which is responsible for the hydroxylation of Δ-6-protoilludene, but the functions of the other CYP450s remain to be determined. Here we describe CYPArm2, which accepts Δ-6-protoilludene and 8α-hydroxy-6-protoilludene as substrates. To investigate the products in more detail, we generated recombinant Saccharomyces cerevisiae strains overexpressing CYPArm2 in combination with the previously characterized protoilludene synthase and 8α-hydroxylase. Using this total biosynthesis approach, sufficient quantities of product were obtained for NMR spectroscopy. This allowed the identification of 8α,13-dihydroxy-protoilludene, confirming that CYPArm2 is a protoilludene 13-hydroxylase.

Chemistry, Chemo-Ecology, and Biological Activities of Uncommon and Structurally Diverse Sesquiterpenoids from the Sanya Bay Nudibranch Hexabranchus sanguineus.

A detailed chemical investigation of the Sanya Bay nudibranch Hexabranchus sanguineus yielded thirteen new sesquiterpenoids, namely sanyagunins A-H, sanyalides A-C, and sanyalactams A and B, along with eleven known related ones. Sanyalactams A and B feature an unprecedented hexahydrospiro[indene-2,3'-pyrrolidine] core. The structures of new compounds were established by a combination of extensive spectroscopic data analysis, quantum mechanical-nuclear magnetic resonance methods, the modified Mosher's method, and X-ray diffraction analysis. Based on analysis of NOESY correlations and the modified Mosher's method, the stereochemistry of two known furodysinane-type sesquiterpenoids were revised. A plausible biogenetic relationship between these sesquiterpenoids wasproposed and discussed, and a chemo-ecological relationship of the title animal and its possible sponge preys has been analyzed. In bioassays, sanyagunin B showed moderate antibacterial activity, whereas 4α-formamidogorgon-11-ene exhibited potent cytotoxicity with IC50 values ranging from 0.87 to 1.95 µM.

Natural compound So-2 suppresses triple-negative breast cancer through inducing ferroptosis via downregulating transcription factor E2F7.

Triple-negative breast cancer (TNBC), accounting for about 15∼18% of all breast cancers, is notorious for its poor prognosis, high rate of relapse and short overall survival. Because of lacking effective therapeutic targets or drugs, treatment of TNBC in clinical encounters great obstacle. Siegesbeckiaorientalis L. have been used as a traditional Chinese medicine "Xi-Xian-Cao" for centuries with multiple medicinal benefits including cancerous treatment. We have reported the isolation of twenty-seven germacranolides including So-2 from the aerial parts of S. orientalis with potent cytotoxicity against breast cancer cells. The studyaims to verified the anti-TNBC function of the natural compound So-2 both in vitro and vivo and uncover the underlying mechanism. The results showed that So-2 caused cell cycle arrest and suppress TNBC cell proliferation and migration. Also, So-2 was first identified to be a bona fide ferroptosis inducer in TNBC cells. So-2 effectively suppressed tumor growth of TNBC by using an orthotopic transplantation tumor model. We also characterized the oncogenic role of the transcription factor E2F7 in TNBC. E2F7 was demonstrated to be involved in the ferroptosis-inducing and tumor suppression effect of So-2. Altogether, So-2 exhibits inhibitory effect on TNBC both in vitro and vivo by inducing TNBC ferroptosis via downregulating the expression of E2F7. These findings provide valuable insight into the pathogenesis of TNBC. The natural compound So-2, isolated from Chinese traditional medicine, might be a prospective drug candidate in TNBC therapy.