Chemoenzymatic Synthesis of a New Germacrene Derivative Named Germacrene F.

The new farnesyl pyrophosphate (FPP) derivative with a shifted olefinic double bond from C6-C7 to C7-C8 is accepted and converted by the sesquiterpene cyclases protoilludene synthase (Omp7) as well as viridiflorene synthase (Tps32). In both cases, a so far unknown germacrene derivative was found to be formed, which we name "germacrene F". Both cases are examples in which a modification around the central olefinic double bond in FPP leads to a change in the mode of initial cyclization (from 1→11 to 1→10). For Omp7 a rationale for this behaviour was found by carrying out molecular docking studies. Temperature-dependent NMR experiments, accompanied by NOE studies, show that germacrene F adopts a preferred mirror-symmetric conformation with both methyl groups oriented in the same directions in the cyclodecane ring.

Cytotoxic Pentaketide-Sesquiterpenes from the Marine-Derived Fungus Talaromyces variabilis M22734.

Talaromyces, a filamentous fungus widely distributed across terrestrial and marine environments, can produce a diverse array of natural products, including alkaloids, polyketones, and polyketide-terpenoids. Among these, chrodrimanins represented a typical class of natural products. In this study, we isolated three previously undescribed pentaketide-sesquiterpenes, 8,9-epi-chrodrimanins (1-3), along with eight known compounds (4-11). The structures of compounds 1-3 were elucidated using nuclear magnetic resonance (NMR) and mass spectrometry (MS), while their absolute configurations were determined through X-ray crystallography and electronic circular dichroism (ECD) computations. The biosynthetic pathways of compounds 1-3 initiate with 6-hydroxymellein and involve multiple stages of isoprenylation, cyclization, oxidation, and acetylation. We selected four strains of gastrointestinal cancer cells for activity evaluation. We found that compound 3 selectively inhibited MKN-45, whereas compounds 1 and 2 exhibited no significant inhibitory activity against the four cell lines. These findings suggested that 8,9-epi-chrodrimanins could serve as scaffold compounds for further structural modifications, potentially leading to the development of targeted therapies for gastric cancer.

Essential oils and their nanoformulations for breast cancer therapy.

Breast Cancer (BC) is the most prevalent type of cancer in the world. Current treatments include surgery, radiation, and chemotherapy but often are associated with high toxicity to normal tissues, chemoresistance, and relapse. Thus, developing novel therapies which could combat these limitations is essential for effective treatment. In this context, phytochemicals are increasingly getting popular due to their safety profile, ability to efficiently target tumors, and circumvent limitations of existing treatments. Essential Oils (EOs) are mixtures of various phytochemicals which have shown potential anticancer activity in preclinical BC models. However, their clinical translation is limited by factors such as high volatility, low stability, and poor solubility. Nanotechnology has facilitated their encapsulation in a variety of nanostructures and proven to overcome these limitations. In this review, we have efficiently summarized the current knowledge on the anticancer effect of EOs and constituents in both in in vitro and in in vivo BC models. Further, we also provide a descriptive account on the potential of nanotechnology in enhancing the anti-BC activity of EOs and their constituents. The papers discussed in this review were selected using the keywords "antiproliferative Essential Oils in breast cancer," "anticancer activity of Essential Oil in breast cancer," and "cytotoxicity of Essential Oils in breast cancer" performed in PubMed and ScienceDirect databases.

Isolation and Bioactivity Evaluation of Sesquiterpenes from an Alcyonarian of the Genus Lemnalia from the Saudi Arabian Red Sea.

Over the last decades, soft corals have been proven a rich source of biologically active compounds, featuring a wide range of chemical structures. Herein, we investigated the chemistry of an alcyonarian of the genus Lemnalia (Neptheidae), specimens of which were collected from the coral reefs near Al Lith, on the south-west coast of Saudi Arabia. A series of chromatographic separations led to the isolation of 31 sesquiterpenes, featuring mainly the nardosinane and neolemnane carbon skeletons, among which three (13, 14 and 28) are new natural products. The metabolites isolated in sufficient amounts were evaluated in vitro in human tumor and non-cancerous cell lines for a number of biological activities, including their cytotoxic, anti-inflammatory, anti-angiogenic, and neuroprotective activities, as well as for their effect on androgen receptor (AR)-regulated transcription. Among the tested metabolites, compound 12 showed comparable neuroprotective activity to the positive control N-acetylcysteine, albeit at a 10-fold lower concentration.

Chemical Composition of Artemisia Scoparia and Their Bioactivities.

Three undescribed sesquiterpenes (1-3), two enantiomeric pairs of monoterpenes (4a/4b-5a/5b), one alkyne (6), two known alkynes (7-8) and eight known coumarins (9-16) were isolated from the aerial parts extracts of Artemisia scoparia. The structures of these compounds were fully elucidated by their 1D and 2D NMR, HRESIMS spectral data analyses, and comparison with literature. The absolute configurations of compounds were determined by single-crystal X-ray crystallography (1), a comparison of experimental and calculated electronic circular dichroism (ECD) data (2-6). 15 showed moderate inhibitory activity with the NO release in LPS-induced RAW264.7 cells. 9-16 showed varying degrees of promoting melanogenesis and tyrosinase activity in B16 cells.

Atramacrolodes A-D (1-4), Four Undescribed Eudesmane-type Sesquiterpenes from the Rhizome of Atractylodes macrocephala.

Four undescribed sesquiterpenes, atramacrolodes A-D (1-4), along with six known compounds 5-10 were isolated from the rhizome of Atractylodes macrocephala. Compound 3 possessed a new skeleton based on an unprecedented carton-carton connection. Their structures were determined by UV, IR, HRESIMS, NMR spectra, 13C NMR calculation with DP4+ analysis, and the comparison of experimental and calculated ECD spectra. Compounds 5 and 8 showed protective effects against paracetamol-induced liver cell injury.

Two new guaiane-type sesquiterpenes from Curcuma wenyujin.

Two new guaiane-type sesquiterpenes, wenyujinolides A (1) and B (2), were isolated from the ethanol extract of Curcuma wenyujin, together with 10 known compounds. Their structures were established by extensive spectroscopic methods (IR, ESIMS, HRESIMS, ECD, 1D and 2D NMR) and comparison of their NMR data with literatures. Compounds 1 and 2 were evaluated for the inhibition of NO production in LPS induced RAW 264.7 macrophages.

Cadinane sesquiterpenes from the stems and branches of Illicium ternstroemioides.

Three new cadinane sesquiterpenes (1-3) and three known sesquiterpenes were isolated from the stems and branches of Illicium ternstroemioides A. C. Smith. The structures of the new compounds were elucidated by extensive analysis of spectroscopic and HRESIMS data. The structures of illiternins A-C (1-3) were confirmed by single crystal X-ray diffraction, allowing for the determination of their absolute configurations. Compounds 3 and 6 exhibited antiviral activity against Coxsackievirus B3 with IC50 values of 33.3 and 57.7 µM, respectively.

Sesquiterpenes from Wikstroemia lungtzeensis with anti-neuroinflammatory effects.

An anti-neuroinflammatory activities-guided phytochemical research of Wikstroemia lungtzeensis was performed for the first time. Three undescribed carotane-type sesquiterpenes, excoecafolinols C-E (1-3), and nine known sesquiterpene derivatives were isolated from the effective ethyl acetate extract of W. lungtzeensis. Their structures were determined based on multiple spectroscopic techniques and electronic circular dichroism (ECD) spectra. Furthermore, the anti-neuroinflammatory activities of the identified compounds were evaluated in lipopolysaccharide-stimulated BV-2 cells. Among them, six components (1, 2, 4, 7, 11, 12) exhibited significant inhibitory effects on nitric oxide (NO) production, with IC50 values ranging from 10.48 to 49.41 µM (positive control minocycline, IC50 53.20 µM). Carotane-type sesquiterpenes (1, 2, 4) with high content and significant inhibitory effects, are considered to be major active ingredients of W. lungtzeensis, which might serve as potential therapeutic agents for neurodegenerative diseases.

Unravelling the Function of the Sesquiterpene Cyclase STC3 in the Lifecycle of Botrytis cinerea.

The genome sequencing of Botrytis cinerea supplies a general overview of the map of genes involved in secondary metabolite synthesis. B. cinerea genomic data reveals that this phytopathogenic fungus has seven sesquiterpene cyclase (Bcstc) genes that encode proteins involved in the farnesyl diphosphate cyclization. Three sesquiterpene cyclases (BcStc1, BcStc5 and BcStc7) are characterized, related to the biosynthesis of botrydial, abscisic acid and (+)-4-epi-eremophilenol, respectively. However, the role of the other four sesquiterpene cyclases (BcStc2, BcStc3, BcStc4 and BcStc6) remains unknown. BcStc3 is a well-conserved protein with homologues in many fungal species, and here, we undertake its functional characterization in the lifecycle of the fungus. A null mutant ΔBcstc3 and an overexpressed-Bcstc3 transformant (OvBcstc3) are generated, and both strains show the deregulation of those other sesquiterpene cyclase-encoding genes (Bcstc1, Bcstc5 and Bcstc7). These results suggest a co-regulation of the expression of the sesquiterpene cyclase gene family in B. cinerea. The phenotypic characterization of both transformants reveals that BcStc3 is involved in oxidative stress tolerance, the production of reactive oxygen species and virulence. The metabolomic analysis allows the isolation of characteristic polyketides and eremophilenols from the secondary metabolism of B. cinerea, although no sesquiterpenes different from those already described are identified.

Exploring the Larvicidal and Adulticidal Activity against Aedes aegypti of Essential Oil from Bocageopsis multiflora.

This study investigates the chemical composition of the essential oil obtained from the leaves of Bocageopsis multiflora (Mart.) R.E.Fr (Annonaceae), examining its effectiveness in combating both the larvae and adult forms of Aedes aegypti mosquitoes. Additionally, for a deeper understanding of the insecticidal activity, toxicity properties and molecular docking calculations were conducted using the main compounds of this essential oil. GC/MS analysis revealed the presence of 26 constituents, representing 95.2% of the essential oil, with the major components identified as the sesquiterpenes α-selinene, ß-selinene, and ß-elemene. Larvicidal assays demonstrated potent activity of this essential oil with significant LC50 values of 40.8 and 39.4 µg/mL at 24 and 48 h, respectively. Adulticidal assessments highlighted strong efficacy with LC50 of 12.5 µg/mL. Molecular docking analysis identified optimal interaction activities of α-selinene and ß-selinene with key Aedes proteins. The in silico studies comparing synthetic insecticides with the major sesquiterpenes of the essential oil revealed that ß-selinene exhibited a significantly higher binding affinity compared to the other two sesquiterpenes. Also, ADMET studies of the three main sesquiterpenes indicated acceptable drug-like properties. In these findings, safety evaluations showed low toxicity and skin sensitization for the main sesquiterpenes, contrasting with commercial synthetic insecticides. Therefore, in silico analyses suggest promising interactions with Aedes proteins, indicating its potential as an effective alternative to conventional insecticides These results show the larvicidal and adulticidal potential of the essential oil from Bocageopsis multiflora against Aedes aegypti, supported by its predominant constituents, α-selinene, ß-selinene and ß-elemene.

Antimicrobial Activity of Drimanic Sesquiterpene Compounds from Drimys winteri against Multiresistant Microorganisms.

In this work, a group of ten sesquiterpene drimanes, including polygodial (1), isopolygodial (2), and drimenol (3) obtained from the bark of Drimys winteri F. and seven synthetic derivatives, were tested in vitro against a unique panel of bacteria, fungi, and oomycetes with standardized procedures against bacterial strains K. pneumoniae, S. tiphy, E. avium, and E. coli. The minimum inhibitory concentrations and bactericidal activities were evaluated using standardized protocols. Polygodial (1) was the most active compound, with MBC 8 µg/mL and MIC 16 µg/mL in E. avium; MBC 16 µg/mL and MIC 32 µg/mL in K. pneumoniae; MBC 64 µg/mL and MIC 64 µg/mL in S. typhi; and MBC 8 µg/mL and MIC 16 µg/mL and MBC 32 µg/mL and MIC 64 µg/mL in E. coli, respectively. The observed high potency could be attributed to the presence of an aldehyde group at the C8-C9 position. The antifungal activity of 1 from different microbial isolates has been evaluated. The results show that polygodial affects the growth of normal isolates and against filamentous fungi and oomycetes with MFC values ranging from 8 to 64 µg/mL. Sesquiterpene drimanes isolated from this plant have shown interesting antimicrobial properties.

Phytochemistry and Pharmacology of Sesquiterpenoids from Atractylodes DC. Genus Rhizomes.

The rhizomes of the genus Atractylodes DC. consist of various bioactive components, including sesquiterpenes, which have attracted a great deal of research interest in recent years. In the present study, we reviewed the previously published literatures prior to November 2023 on the chemical structures, biosynthetic pathways, and pharmacological activities of the sesquiterpenoids from this genus via online databases such as Web of Science, Google Scholar, and ScienceDirect. Phytochemical studies have led to the identification of more than 160 sesquiterpenes, notably eudesmane-type sesquiterpenes. Many pharmacological activities have been demonstrated, particularly anticancer, anti-inflammatory, and antibacterial and antiviral activities. This review presents updated, comprehensive and categorized information on the phytochemistry and pharmacology of sesquiterpenes in Atractylodes DC., with the aim of offering guidance for the future exploitation and utilization of active ingredients in this genus.

[Active constituents of essential oil from Curcuma phaeocaulis for treatment of dysmenorrhea].

This study aims to identify the active constituents of essential oil from the rhizomes of Curcuma phaeocaulis for the treatment of dysmenorrhea. The compounds were separated and purified by molecular distillation, silica gel and Sephadex LH-20 column chromatography, preparative thin layer chromatography, and semi-preparative high performance liquid chromatography. Their structures were identified by mass spectrometry and nuclear magnetic resonance spectroscopy. The animal model of primary dysmenorrhea and the contraction model of isolated uterine smooth muscle of rats were established to examine the active constituents in the essential oil for treating dysmenorrhea. Six sesquiterpenes were isolated and identified as dehydrocommiterpene A(1), comosone Ⅱ(2), 5α(H)-eudesma-3(4),7(11)-dien-9ß-ol-6-one(3), guaia-6(7)-en-11-ol(4), curcumenol(5), and isocurcumenol(6), among which compound 1 was a novel compound. The animal experiments showed that the essential oil from C. phaeocaulis significantly lowered the level of PGF_(2α) in uterine tissue compared with the model group. The experiment with the contraction model of isolated uterine smooth muscle demonstrated that the components with high boiling points outperformed those with low boiling points in relaxing the uterine smooth muscle, and compounds 1, 2, 5, and 6 isolated from the fraction with a high boiling point had the effect of relaxing the uterine smooth muscle. Among them, compounds 5 and 6 inhibited the extracellular Ca~(2+) influx and intracellular Ca~(2+) release to relax the uterine smooth muscle. In conclusion, the components with high boiling points and sesquiterpenes are the active components in the essential oil of C. phaeocaulis for treating dysmenorrhea.

[Difference of effective component content and key enzyme gene expression of biosynthesis in Atractylodes chinensis with different leaf shapes].

In this study, four Atractylodes chinensis(A. chinensis) with different leaf shapes, such as the split leaf, long and narrow leaf, oval leaf, and large round leaf, were used as experimental materials to establish a method for simultaneously determining atractylodin, atractylenolide Ⅰ, ß-eudesmol, and atractylon in the rhizome of A. chinensis. The expression of key enzyme genes for biosynthesis of acetyl-CoA carboxylase(ACC), 3-hydroxy-3-methylglutaryl-CoA reductase(HMGR), and farnesyl pyrophosphate synthase(FPPS) was detected by real-time fluorescence quantitative polymerase chain reaction(qRT-PCR). High performance liquid chromatography(HPLC) was used to compare the difference in the content of four active components in A. chinensis with different leaf shapes, and the correlation between the content of active components and the expression of key enzyme genes in biosynthesis was discussed. The results show that there was good linearity among atractylodin, atractylenolide Ⅰ, ß-eudesmol, and atractylon in the range of 3.30-33.00 µg·mL~(-1)(r =0.999 7), 12.04-120.40 µg·mL~(-1)(r =0.999 5), 29.16-291.60 µg·mL~(-1)(r =0.999 5), and 14.20-142.00 µg·mL~(-1)(r =0.999 5), respectively. The average recoveries were 99.77%(RSD=2.1%), 98.56%(RSD=1.2%), 103.0%(RSD=1.2%), and 100.6%(RSD=1.5%), respectively. The method was accurate and had good reproducibility, which could be used to simultaneously detect atractylodin, atractylenolide Ⅰ, ß-eudesmol, and atractylon. The results showed that there were significant differences in the content of four active components in A. chinensis with different leaf shapes. The content of atractylodin, atractylenolide Ⅰ, and ß-eudesmol in A. chinensis with split leaves was the highest, which were 1.341 9, 5.237 2, and 12.084 3 mg·g~(-1), respectively. The content of atractylon in A. chinensis with long and narrow leaves was the highest(5.470 1 mg·g~(-1)). The content of atractylodin, atractylenolide Ⅰ, ß-eudesmol, and atractylon in A. chinensis with oval leaves was the lowest. The total content of the four effective components in descending order was A. chinensis with split leaves > A. chinensis with long and narrow leaves > A. chinensis with large round leaves > A. chinensis with oval leaves. The gene expression levels of key enzymes ACC, HMGR, and FPPS in A. chinensis with split leaves were the highest(P < 0.05), and the gene expression levels of key enzymes ACC and HMGR in A. chinensis with oval leaves were the lowest(P < 0.05). The gene expression level of key enzyme FPPS in A. chinensis with large round leaves was the lowest. In A. chinensis with different leaf shapes, the key enzyme gene ACC was significantly positively correlated with the polyacetylene component, namely atractylodin(P < 0.01), and the key enzyme genes HMGR and FPPS were positively correlated with the sesquiterpene components, namely atractylenolide Ⅰ, ß-eudesmol, and atractylon. In summary, the quality of A. chinensis with split leaves is the best, and the biosynthesis of atractylodin is significantly correlated with the gene expression of key enzyme ACC, which provides a theoretical basis for screening and optimizing the germplasm resources of A. chinensis and improving the quality of medicinal materials.

Unified Synthesis of 2-Isocyanoallopupukeanane and 9-Isocyanopupukeanane through a "Contra-biosynthetic" Rearrangement.

Herein, we describe our synthetic efforts toward the pupukeanane natural products, in which we have completed the first enantiospecific route to 2-isocyanoallopupukeanane in 10 steps (formal synthesis), enabled by a key Pd-mediated cyclization cascade. This subsequently facilitated an unprecedented bio-inspired "contra-biosynthetic" rearrangement, providing divergent access to 9-isocyanopupukeanane in 15 steps (formal synthesis). Computational studies provide insight into the nature of this rearrangement.

Predicting functions of putative fungal sesquiterpene synthase genes based on multiomics data analysis.

Sesquiterpenes (STs) are secondary metabolites, which mediate biotic interactions between different organisms. Predicting the species-specific ST repertoires can contribute to deciphering the language of communication between organisms of the same or different species. High biochemical plasticity and catalytic promiscuity of sesquiterpene synthases (STSs), however, challenge the homology-based prediction of the STS functions. Using integrated analyses of genomic, transcriptomic, volatilomic, and metabolomic data, we predict product profiles for 116 out of 146 putative STS genes identified in the genomes of 30 fungal species from different trophic groups. Our prediction method is based on the observation that STSs encoded by genes closely related phylogenetically are likely to share the initial enzymatic reactions of the ST biosynthesis pathways and, therefore, produce STs via the same reaction route. The classification by reaction routes allows to assign STs known to be emitted by a particular species to the putative STS genes from this species. Gene expression information helps to further specify these ST-to-STS assignments. Validation of the computational predictions of the STS functions using both in silico and experimental approaches shows that integrated multiomic analyses are able to correctly link cyclic STs of non-cadalane type to genes. In the process of the experimental validation, we characterized catalytic properties of several putative STS genes from the mycorrhizal fungus Laccaria bicolor. We show that the STSs encoded by the L.bicolor mycorrhiza-induced genes emit either nerolidol or α-cuprenene and α-cuparene, and discuss the possible roles of these STs in the mycorrhiza formation.

Terpene Synthases in the Biosynthesis of Drimane-Type Sesquiterpenes across Diverse Organisms.

Drimane-type sesquiterpenes (DTSs) are significant terpenoid natural products characterized by their unique C15 bicyclic skeleton. They are produced by various organisms including plants, fungi, bacteria and marine organisms, and exhibit a diverse array of bioactivities. These bioactivities encompass antifeedant, anti-insecticidal, anti-bacterial, anti-fungal, anti-viral and anti-proliferative properties. Some DTSs contribute to the pungent flavor found in herb plants like water pepper, while others serve as active components responsible for the anti-cancer activities observed in medicinal mushrooms such as (-)-antrocin from Antrodia cinnamomea. Recently, DTS synthases have been identified in various organisms, biosynthesizing drimenol, drim-8-ene-11-ol and (+)-albicanol, which all possess the characteristic drimane skeleton. Interestingly, despite these enzymes producing chemical molecules with a drimane scaffold, they exhibit minimal amino acid sequence identity across different organisms. This Concept article focuses on the discovery of DTS synthases and the tailoring enzymes generating the chemical diversity of drimane natural products. We summarize and discuss their key features, including the chemical mechanisms, catalytic motifs and functional domains employed by these terpene synthases to generate DTS scaffolds.

seco-Sesquiterpenes and acorane-type sesquiterpenes with antiviral activity from the twigs and leaves of Illicium henryi Diels.

Chemical investigation of an alcohol extract from the twigs and leaves of Illicium henryi Diels resulted in the isolation of two new acorane-related seco-sesquiterpenes (1 and 3), two new acorane-related seco-norsesquiterpenes (2 and 4), one new 2-epi-cedrane sesquiterpene (5), eight new acorane-type sesquiterpenes (6-13), and a known major constituent of acorenone B (14). Their structures were established by interpreting extensive spectroscopic data, including HRESIMS, NMR (1H and 13C NMR, 1H-1H COSY, HSQC, and HMBC), and NOE difference spectra analysis. The absolute configurations of 1, 2, 4-7, 9, 10, and 14 were determined by X-ray crystallography, while chemical transformation methods were performed with compound 14 as the starting material to elegantly solve the absolute configuration issue of compounds 8 and 11-13. Notably, 1 and 2 are seco-sesquiterpenes that are related to acorane and possess an unusual ketal-linked hemiacetal in a 6,8-dioxabicyclo[3.2.1]octan-7-ol scaffold ring system. Plausible biosynthetic pathways for compounds 1-14, which were derived from the acorane skeleton, were proposed. All the isolated compounds (1-14) were evaluated for their antiviral and cytotoxic activities.

Separation and identification of terpene-conjugated curcuminoids based on liquid chromatography-tandem mass spectrometry and their in vitro anti-inflammatory activities.

Terpene-conjugated curcuminoids are conjugates of curcuminoids and bisabolanes in the rhizomes of Curcuma longa L. The fragmentation pathways of known three terpene-conjugated curcuminoids (bisabolocurcumin-ether, bisabocurcumin, and demethoxybisabolocurcumin ether) and curcumin, demethoxycurcumin, and bisdemethoxycurcumin were investigated using high-performance liquid chromatography-electrospray ionization tandem mass spectrometry in negative mode to rapidly search and discover similar unknown compounds of the acetone fraction of turmeric. Subsequently, compounds 1-3 were founded in the acetone fraction based on molecular weight and above fragmentation pathways (the characteristic fragment ions, the most and second most abundant fragment ions produced in MS2 spectra). Terpecurcumin X (1) and terpecurcumin Y (3) were further separated by liquid chromatography-tandem mass spectrometry guided isolation technique to verify their structures by nuclear magnetic resonance, electrospray ionization high-resolution mass spectroscopy, ultraviolet and visible spectra and infrared spectra. Interestingly, 1 and 3 were new compounds. The results indicate the feasibility and significant advantages of liquid chromatography-tandem mass spectrometry for the rapid discovery and analysis of new constituents in traditional Chinese medicine. In vitro, Terpene-conjugated curcuminoids had better nitric oxide inhibitory activity than the other seven curcuminoids (demethoxycurcumin, bisdemethoxycurcumin, curdione, curcumenone, bisacurone, curcumenol, and germacron).