DataSheet1_Novel Triterpenoid Alkaloids With Their Potential Cytotoxic Activity From the Roots of Siraitia grosvenorii.docx

Four novel triterpenoid alkaloids, siragrosvenins A–D (1–4), and two new cucurbitane-type triterpenoids, siragrosvenins E–F (5, 6), together with eight known analogs (7−14), were isolated from the roots of Siraitia grosvenorii. Compounds 1−4 possessed a rare cucurbitane-type triterpenoid scaffold, featuring an extra pyrazine unit via the Strecker reaction in the cucurbitane framework. Compound 5 displayed a 6/6/6/5/6/5-fused polycyclic ring system, with an uncommon fused furan and pyran ring in the side chain. All the structures were characterized by extensive spectroscopic analysis, including HRESIMS, NMR, and X-ray crystallographic data. It is worth noting that the DP4+ analysis method was applied for the first time to determine the absolute configurations of the trihydroxybutyl moiety in the side chain of compounds 1–4. In vitro cytotoxicity screening found that compounds 4, 8, 9, 13, and 14 exhibited remarkable cytotoxic activities against three cell lines with IC50 values ranging from 1.44 to 9.99 μM. Siragrosvenin D shows remarkable cytotoxic activity on MCF-7 cells. As a result, it inhibited the proliferation of MCF-7 cells and reduced their viability via the induction of G2/M phase arrest and significantly induced apoptosis in MCF-7 cells.</p

Discovery of Cadinane-Type Sesquiterpenoids from the Infected Stems of Hibiscus tiliaceus as Potential Agrochemical Fungicides

Ten new cadinane-type sesquiterpenoids, named hibisceusins I–R (1–10), along with 14 known sesquiterpenoids (11–24), were acquired from the tainted stems of Hibiscus tiliaceus. Their structures were identified via spectroscopic analysis, one-dimensional (1D) and two-dimensional (2D) NMR, and computer-assisted structure elucidation techniques, including infrared (IR) and mass spectrometry (MS) data. Additionally, subsequent DP4/DP4+ probability methods were used to resolve 3′s relative configurations by comparing their experimental values to the predicted NMR data. The absolute configurations of compounds 1–4 were measured through electronic circular dichroism (ECD) spectra. The ability of all isolates to inhibit the growth of five phytopathogenic fungi (Rhizopus stolonifer, Verticillium dahliae Kleb., Thanatephorus cucumeris, Fusarium oxysporum Schltdl., and F. oxysporum HK-27) was evaluated. Aldehydated sesquiterpenoids (1, 6–9, 11, 12, and 22) and a known sesquiterpenoid quinine (18) exhibited significant inhibitory activities against V. dahliae, T. cucumeris, F. oxysporum, and F. oxysporum HK-27 with minimum inhibitory concentration (MIC) values of 2.5–50 μg/mL, but all isolates remained inactive against R. stolonifer. Moreover, the effects of the isolates on the mycelial morphology were watched through scanning electron microscopy. This study revealed that aldehydated cadinane-type sesquiterpenoids could be used as novel antifungal molecules to develop agrochemical fungicides in plant protection

Eleucanainones A and B: Two Dimeric Structures from the Bulbs of <i>Eleutherine americana</i> with Anti-MRSA Activity

Two naphthoquinone-derived heterodimers with unprecedented carbon skeletons, eleucanainones A (1) and B (2), were isolated from the bulbs of Eleutherine americana. Their structures were elucidated by comprehensive spectroscopic methods. The structures of 1 and 2 were determined to be the first examples of dibenzofuran- and naphthalenone-containing naphthoquinone dimers. Compound 1 exhibited significant anti-MRSA activity in vitro with minimum inhibitory concentration (MIC) values of 0.78 μg/mL by downregulation of basal expression of agrA, cidA, icaA and sarA in methicillin-resistant S. aureus (MRSA)

A Gatekeeper Residue Controls Aromatic Acceptor Specificity of the PHB-Type UbiA Prenyltransferases

UbiA prenyltransferases (PTs) play an important role in prenylation of aromatic compounds with diverse bioactivities. The deep and comprehensive understanding of their substrate selectivity and catalytic mechanism will facilitate the expansion of the robust biocatalytic tools for prenylation of aromatic compounds. Herein, we identified an atypical PHB-type UbiA PT (ClaS) from the basidiomycete Clitocybe clavipes. Unexpectedly, ClaS transferred geranyl pyrophosphate (GPP) to hydroquinone (HYQ) instead of p-hydroxybenzoic acid (PHB). Interestingly, the mutant H73R of ClaS completely switched the substrate preference from HYQ to PHB. Further, the conserved residues His and Arg at the substrate binding site were characterized as the gatekeeper residue of PHB-type UbiA PTs for recognition of the substrates HYQ and PHB, respectively. The structure of ClaS was predicted, and the substrates were docked into ClaS to investigate the catalytic and substrate selectivity mechanisms. QM calculations suggested that the proton transfer from the hydroxyl group of HYQ to the leaving pyrophosphate group may facilitate the nucleophilicity of the substrate. The structural analysis based on MD simulations showed that the pre-reaction state (PRS) occupancy in the complex WT-HYQ and mutant H73R-PHB was favorable for the formation of final products. Analysis of binding free energy further disclosed that the substrate selectivity may be controlled by the different interactions between the hydroxyl or carboxyl group of the substrate and the gatekeeper residues. Finally, we expanded the utility of ClaS by mutating the gatekeeper residue to catalyze the prenylation of various substituted-PHB analogues. Our findings reveal the molecular basis of the PHB-type UbiA PTs for recognizing and catalyzing different substrates and enable us to engineer them for the enzymatic or microbial production of prenylated aromatic compounds

Antimalarial and Antiproliferative Cassane Diterpenes of <i>Caesalpinia sappan</i>

Bioassay-guided fractionation of a methanol extract of the seeds of <i>Caesalpinia sappan</i> led to the isolation of 12 new cassane-type diterpenes, caesalsappanins A–L (<b>1</b>–<b>12</b>). Their structures were elucidated on the basis of NMR and HRESIMS analysis, and the absolute configuration of compound <b>1</b> was determined by single-crystal X-ray crystallography. All isolated compounds were tested against a chloroquine-resistant <i>Plasmodium falciparum</i> strain for antiplasmodial activities and against a small panel of human cancer cell lines for antiproliferative activities. Compounds <b>7</b> and <b>8</b> displayed antimalarial activity against the chloroquine-resistant K1 strain of <i>P. falciparum</i> with IC₅₀ values of 0.78 and 0.52 μM and selectivity indices of 17.6 and 16.4, respectively. Compound <b>10</b> showed antiproliferative activity against the KB cancer cell line with an IC₅₀ value of 7.4 μM

Presentation1_Cyclohexene oxide CA, a derivative of zeylenone, exhibits anti-cancer activity in glioblastoma by inducing G0/G1 phase arrest through interference with EZH2.ZIP

Introduction: Due to its highly aggressiveness and malignancy, glioblastoma (GBM) urgently requires a safe and effective treatment strategy. Zeylenone, a natural polyoxygenated cyclohexenes compound isolated from Uvaria grandiflora, has exhibited potential biological activities in various human diseases, including tumors.Methods: We designed and synthesized a series of (+)-Zeylenone analogues and evaluated their anti-GBM roles through structural-activity analysis. Cell Counting Kit-8, TUNEL, transwell and flow cytometry were employed for investigating the anticancer effects of CA on GBM cells. Western blotting, molecular docking, qRT-PCR and ChIP assays were performed to reveal the underlying mechanisms by which CA regulates the GBM cell cycle. The nude mouse xenograft model, HE staining, immunohistochemistry and was used to evaluate the anticancer effect of CA in vivo.Results: We identified CA ((1R, 2R, 3S)-3-p-fluorobenzoyl-zeylenone) as having the lowest IC50 value in GBM cells. CA treatment significantly inhibited the malignant behaviors of GBM cells and induced G0/G1 phase arrest in vitro. Furthermore, we validated the molecular mechanism by which CA interferes with EZH2, attenuating the down-regulation of cyclin-dependent kinase inhibitors p27 and p16 by the PRC2 complex. By establishing orthotopic nude mice models, we further validated the inhibitory role of CA on tumorigenesis of GBM cells in vivo and its potential values to synergistically potentiate the anti-tumor effects of EZH2 inhibitors.Conclusion: Overall, this paper elucidated the anti-GBM effects and potential mechanisms of CA, and may provide a therapeutic drug candidate for GBM treatment.</p

Image1_Cyclohexene oxide CA, a derivative of zeylenone, exhibits anti-cancer activity in glioblastoma by inducing G0/G1 phase arrest through interference with EZH2.TIF

Introduction: Due to its highly aggressiveness and malignancy, glioblastoma (GBM) urgently requires a safe and effective treatment strategy. Zeylenone, a natural polyoxygenated cyclohexenes compound isolated from Uvaria grandiflora, has exhibited potential biological activities in various human diseases, including tumors.Methods: We designed and synthesized a series of (+)-Zeylenone analogues and evaluated their anti-GBM roles through structural-activity analysis. Cell Counting Kit-8, TUNEL, transwell and flow cytometry were employed for investigating the anticancer effects of CA on GBM cells. Western blotting, molecular docking, qRT-PCR and ChIP assays were performed to reveal the underlying mechanisms by which CA regulates the GBM cell cycle. The nude mouse xenograft model, HE staining, immunohistochemistry and was used to evaluate the anticancer effect of CA in vivo.Results: We identified CA ((1R, 2R, 3S)-3-p-fluorobenzoyl-zeylenone) as having the lowest IC50 value in GBM cells. CA treatment significantly inhibited the malignant behaviors of GBM cells and induced G0/G1 phase arrest in vitro. Furthermore, we validated the molecular mechanism by which CA interferes with EZH2, attenuating the down-regulation of cyclin-dependent kinase inhibitors p27 and p16 by the PRC2 complex. By establishing orthotopic nude mice models, we further validated the inhibitory role of CA on tumorigenesis of GBM cells in vivo and its potential values to synergistically potentiate the anti-tumor effects of EZH2 inhibitors.Conclusion: Overall, this paper elucidated the anti-GBM effects and potential mechanisms of CA, and may provide a therapeutic drug candidate for GBM treatment.</p

Antimalarial and Antiproliferative Cassane Diterpenes of <i>Caesalpinia sappan</i>

Bioassay-guided fractionation of a methanol extract of the seeds of <i>Caesalpinia sappan</i> led to the isolation of 12 new cassane-type diterpenes, caesalsappanins A–L (<b>1</b>–<b>12</b>). Their structures were elucidated on the basis of NMR and HRESIMS analysis, and the absolute configuration of compound <b>1</b> was determined by single-crystal X-ray crystallography. All isolated compounds were tested against a chloroquine-resistant <i>Plasmodium falciparum</i> strain for antiplasmodial activities and against a small panel of human cancer cell lines for antiproliferative activities. Compounds <b>7</b> and <b>8</b> displayed antimalarial activity against the chloroquine-resistant K1 strain of <i>P. falciparum</i> with IC₅₀ values of 0.78 and 0.52 μM and selectivity indices of 17.6 and 16.4, respectively. Compound <b>10</b> showed antiproliferative activity against the KB cancer cell line with an IC₅₀ value of 7.4 μM

Two new cycloartane triterpenoid glycosides from the rhizomes of <i>Actaea vaginata</i>

Two new cycloartane triterpenoid glycosides, soulieoside V (1) and 15-deacetylbeesioside O (2), together with one known compound, beesioside J (3), were isolated from the ethanolic extract of the rhizomes of Actaea vaginata. Their structures were elucidated by spectroscopic methods and by comparison with data reported in the literature. All the compounds were tested for their cytotoxic activities against human cancer cell lines.</p

Two Cytochrome P450 Enzymes Form the Tricyclic Nested Skeleton of Meroterpenoids by Sequential Oxidative Reactions

Meroterpenoid clavilactones feature a unique benzo-fused ten-membered carbocyclic ring unit with an α,β-epoxy-γ-lactone moiety, forming an intriguing 10/5/3 tricyclic nested skeleton. These compounds are good inhibitors of the tyrosine kinase, attracting a lot of chemical synthesis studies. However, the natural enzymes involved in the formation of the 10/5/3 tricyclic nested skeleton remain unexplored. Here, we identified a gene cluster responsible for the biosynthesis of clavilactone A in the basidiomycetous fungus Clitocybe clavipes. We showed that a key cytochrome P450 monooxygenase ClaR catalyzes the diradical coupling reaction between the intramolecular hydroquinone and allyl moieties to form the benzo-fused ten-membered carbocyclic ring unit, followed by the P450 ClaT that exquisitely and stereoselectively assembles the α,β-epoxy-γ-lactone moiety in clavilactone biosynthesis. ClaR unprecedentedly acts as a macrocyclase to catalyze the oxidative cyclization of the isopentenyl to the nonterpenoid moieties to form the benzo-fused macrocycle, and a multifunctional P450 ClaT catalyzes a ten-electron oxidation to accomplish the biosynthesis of the 10/5/3 tricyclic nested skeleton in clavilactones. Our findings establish the foundation for the efficient production of clavilactones using synthetic biology approaches and provide the mechanistic insights into the macrocycle formation in the biosynthesis of fungal meroterpenoids