Artemyriantholides A-K, guaiane-type sesquiterpenoid dimers from Artemisia myriantha var. pleiocephala and their antihepatoma activity.

Artemyriantholides A-K (1-11) as well as 14 known compounds (12-25) were isolated from Artemisia myriantha var. pleiocephala (Asteraceae). The structures and absolute configuration of compounds 2 and 8-9 were confirmed by the single crystal X-ray diffraction analyses, and the others were elucidated by MS, NMR spectral data and electronic circular dichroism calculations. All compounds were chemically characterized as guaiane-type sesquiterpenoid dimers (GSDs). Compound 1 was the first example of the GSD fused via C-3/C-11' and C-5/C-13' linkages, and compounds 2 and 5 were rare GSDs containing chlorine atoms. Eleven compounds showed obvious inhibitory activity in HepG2, Huh7 and SK-Hep-1 cell lines by antihepatoma assay to provide the IC50 values ranging from 7.9 to 67.1 µM. Importantly, compounds 5 and 8 exhibited the best inhibitory activity with IC50 values of 14.2 and 18.8 (HepG2), 9.0 and 11.5 (Huh7), and 8.8 and 11.3 µM (SK-Hep-1), respectively. The target of compound 5 was predicted to be MAP2K2 by a computational prediction model. The interaction between compound 5 and MAP2K2 was conducted to give docking score of -9.0 kcal/mol by molecular docking and provide KD value of 43.7 µM by Surface Plasmon Resonance assay.

A derivative of trihydroxynaphthalenone and a pyrone metabolite from the endophytic fungus Talaromyces purpurpgenus.

A newly discovered trihydroxynaphthalenone derivative, epoxynaphthalenone (1) involving the condensation of ortho-hydroxyl groups into an epoxy structure, and a novel pyrone metabolite characterized as pyroneaceacid (2), were extracted from Talaromyces purpurpgenus, an endophytic fungus residing in Rhododendron molle. The structures of these compounds were elucidated through a comprehensive analysis of their NMR and HRESIMS data. The determination of absolute configurations was accomplished using electronic circular dichroism (ECD) calculations and CD spectra. Notably, these recently identified metabolites exhibited a moderate inhibitory activity against xanthine oxidase (XOD).

Artemdubosides A-G, seven unusual polyacetylenes from Artemisia dubia var. subdigitata and their antihepatoma activity.

Artemdubosides A-E (1-5), the first examples of natural polyacetylenes substituted by 6'-O-crotonyl ß-glucopyranoside, and artemdubosides F-G (6-7) that were two unusual polyacetylenes featuring a 6'-O-acetyl ß-glucopyranoside moiety, were isolated from Artemisia dubia var. subdigitata. Their structures were elucidated based on the spectral data including HRESIMS, UV, IR, 1D and 2D NMR, and ECD calculations. Antihepatoma assay suggested that compound 1 exhibited activity against HepG2, Huh7, and SK-Hep-1 cells with inhibitory ratios of 77.1%, 90.8%, and 73.1% at 200.0 µM, respectively.

Synthesis and antihepatoma activity of guaianolide dimers derived from lavandiolide I.

Guaianolide dimers represent a unique class of natural products with anticancer activities, but their low content in plants has limited in-depth pharmacological studies. Lavandiolide I is a guaianolide dimer isolated from Artemisia species, and had been synthesized on a ten-gram scale in four steps with 60 % overall yield, which showed potent antihepatoma activity on the HepG2, Huh7, and SK-Hep-1 cell lines with IC50 values of 12.1, 18.4, and 17.6 µM, respectively. To explore more active dimers, 33 lavandiolide I derivatives were designed, synthesized, and evaluated for their inhibitory activity on human hepatoma cell lines. Among them, 10 derivatives were more active than lavandiolide I and sorafenib on the three cell lines. The primary structure-activity relationship concluded that the introduction of aldehyde, ester, azide, amide, carbamate and urea functional groups at C-14' of the guaianolide dimer significantly enhanced the antihepatoma activity. Among these compounds, derivatives 25, 27, and 33 enhanced antihepatoma activity more than 1.2-5.8 folds than that of lavandiolide I, and demonstrated low toxicity to the human liver cell lines (THLE-2) and good safety profiles with selective index ranging from 1.3 to 3.4, while lavandiolide I was more toxic to THLE-2 cells. This work provides new insights into enhancing the antihepatoma efficacy and reducing the toxicity of sesquiterpenoid dimers.

Supramolecular helix of an oligomeric azapeptide building block containing four ß-turn structures.

Oligomers of benzoylalanine-based amidothioureas containing four ß-turn structures spaced by meta-substituted benzenes were shown to undergo assembly in dilute CH3CN solution into supramolecular helices of enhanced supramolecular helicity, whereas those spaced by para-substituted benzene spacer(s) or those spaced by meta-substituted benzenes but with one or two ß-turns exhibit a substantially decreased tendency of assembling.

Characterization and Engineering of Two Highly Paralogous Sesquiterpene Synthases Reveal a Regioselective Reprotonation Switch.

Sesquiterpene synthases (STPSs) catalyze carbocation-driven cyclization reactions that can generate structurally diverse hydrocarbons. The deprotonation-reprotonation process is widely used in STPSs to promote structural diversity, largely attributable to the distinct regio/stereoselective reprotonations. However, the molecular basis for reprotonation regioselectivity remains largely understudied. Herein, we analyzed two highly paralogous STPSs, Artabotrys hexapetalus (-)-cyperene synthase (AhCS) and ishwarane synthase (AhIS), which catalyze reactions that are distinct from the regioselective protonation of germacrene A (GA), resulting in distinct skeletons of 5/5/6 tricyclic (-)-cyperene and 6/6/5/3 tetracyclic ishwarane, respectively. Isotopic labeling experiments demonstrated that these protonations occur at C3 and C6 of GA in AhCS and AhIS, respectively. The cryo-electron microscopy-derived AhCS complex structure provided the structural basis for identifying different key active site residues that may govern their functional disparity. The structure-guided mutagenesis of these residues resulted in successful functional interconversion between AhCS and AhIS, thus targeting the three active site residues [L311-S419-C458]/[M311-V419-A458] that may act as a C3/C6 reprotonation switch for GA. These findings facilitate the rational design or directed evolution of STPSs with structurally diverse skeletons.

Preserving Structurally Labile Peptide Nanosheets After Molecular Functionalization of the Self-Assembling Peptides.

A significant challenge in creating supramolecular materials is that conjugating molecular functionalities to building blocks often results in dissociation or undesired morphological transformation of their assemblies. Here we present a facile strategy to preserve structurally labile peptide assemblies after molecular modification of the self-assembling peptides. Sheet-forming peptides are designed to afford a staggered alignment with the segments bearing chemical modification sites protruding from the sheet surfaces. The staggered assembly allows for simultaneous separation of attached molecules from each other and from the underlying assembly motifs. Strikingly, using PEGs as the external molecules, PEG400 - and PEG700 -peptide conjugates directly self-associate into nanosheets with the PEG chains localized on the sheet surfaces. In contrast, the sheet formation based on in-register lateral packing of peptides does not recur upon the peptide PEGylation. This strategy allows for fabrication of densely modified assemblies with a variety of molecules, as demonstrated using biotin (hydrophobic molecule), c(RGDfK) (cyclic pentapeptide), and nucleic acid aptamer (negatively charged ssDNA). The staggered co-assembly also enables extended tunability of the amount/density of surface molecules, as exemplified by screening ligand-appended assemblies for cell targeting. This study paves the way for functionalization of historically challenging fragile assemblies while maintaining their overall morphology.

Highly oxygenated guaiane-type sesquiterpene lactones from Artemisia sacrorum and their antihepatoma activity.

The ethanol and EtOAc extracts of Artemisia sacrorum exhibited inhibitory effect against HepG2, Huh7, and SK-Hep-1 cell lines with inhibitory ratios of 65.5%, 28.1%, 84.6%, and 93.5%, 82.0%, 89.0% at 200 µg/mL. Twenty-three undescribed guaiane-type sesquiterpene lactones, artemisacrolides A‒W, were isolated from A. sacrorum under the guidance of antihepatoma activity. Their structures were elucidated by spectral data (HRESIMS, IR, UV, 1D and 2D NMR), ECD calculations, and a single-crystal X-ray diffraction. Artemisacrolides A‒U were guaiane-type sesquiterpene lactones possessing α-methylene-γ-lactone and containing acetoxyl groups at C-8, and artemisacrolides V and W represented the first report from the genus Artemisia with a 1,10-rearranged guaiane-type sesquiterpene lactone. Antihepatoma assay suggested that artemisacrolides A‒U demonstrated better inhibitory activity in Huh7 and SK-Hep-1 cells than those of HepG2 cells. Among them, nine compounds exhibited significant inhibitory activity against Huh7 cells with IC50 values of 8.2-14.3 µM, superior or equal to that of sorafenib; seven compounds demonstrated obvious activity against SK-Hep-1 cells with IC50 values of 13.5-19.2 µM, which were equivalent to that of sorafenib. Artemisacrolides B and E were the most active ones in three human hepatoma cell lines with IC50 values of 21.9, 8.2, 16.9 and 22.6, 9.0, 17.3 µM.

Computational exploration of the significance of COPS6 in cancer: Functional and clinical relevance across tumor types.

BACKGROUND: The COP9 signalosome subunit 6 (COPS6) has been implicated in cancer progression, while its precise role in most types of cancer remains elusive. AIM: To investigate the functional and clinical relevance of COPS6 across various tumor types using publicly available databases. METHODS: We used R software and online analysis databases to analyze the differential expression, prognosis, mutation and related functions of COPS6 in pan-cancer. RESULTS: Differential expression analysis and survival analysis demonstrated that COPS6 was highly expressed and associated with high-risk profiles in the majority of cancer types. Possible associations between COPS6 expression level and prognostic outcomes were found using data from public databases. Mutational analysis revealed that missense mutations were the predominant type of COPS6 mutation. Additionally, positive correlations were identified between COPS6 expression level and tumor mutational burden and microsatellite instability in most types of cancer. Immune infiltration analysis demonstrated a negative correlation between COPS6 expression level and CD8+ T cell infiltration in certain types of cancer. The correlation between COPS6 expression level and cancer-associated fibroblast infiltration exhibited heterogeneity, in which a positive correlation was found in head and neck squamous cell carcinoma and tenosynovial giant cell tumor, and a negative correlation was identified in diffuse large B-cell lymphoma and thymoma. The correlation between COPS6 expression level and macrophage infiltration was closely related to macrophage type. Gene co-expression and enrichment analysis highlighted transcription elongation factor B polypeptide 2 and G protein pathway suppressor 1 were significantly and positively associated with COPS6 expression level. These genes were predominantly involved in processes, such as ubiquitin-mediated proteolysis and human immunodeficiency virus 1 infection. CONCLUSION: In conclusion, this study systematically explored the significance of COPS6 across different tumor types, providing a solid foundation for considering COPS6 as a novel biomarker in cancer research.

Artemongolins A-K, undescribed germacrane-guaiane sesquiterpenoid dimers from Artemisia mongolica and their antihepatoma activities.

Artemongolins A-K (1-11), which are undescribed sesquiterpenoid dimers, were obtained from Artemisia mongolica and characterized through comprehensive spectral data, including HRESIMS, IR, 1D and 2D NMR, and ECD calculations. The absolute configurations of compounds 1, 4, and 7 were undoubtedly determined by a single-crystal X-ray crystallography. Artemongolins A-K (1-11) featured a rare 5/7/5/5/5/10 hexacyclic system composed of a germacrene and a guaianolide by a fused 2-oxaspiro[4,4]nonane-1-one ring system. Antihepatoma evaluation against three human hepatoma cell lines demonstrated that the most active compounds 5 and 6 displayed inhibitory activity with IC50 values of 88.6 and 57.0 (HepG2), 59.1 and 26.4 (Huh7), and 67.5 and 32.5 (SK-Hep-1) µM, respectively.

Reassembly of Peptide Nanofibrils on Live Cell Surfaces Promotes Cell-Cell Interactions.

Nature regulates cellular interactions through the cell-surface molecules and plasma membranes. Despite advances in cell-surface engineering with diverse ligands and reactive groups, modulating cell-cell interactions through scaffolds of the cell-binding cues remains a challenging endeavor. Here, we assembled peptide nanofibrils on live cell surfaces to present the ligands that bind to the target cells. Surprisingly, with the same ligands, reducing the thermal stability of the nanofibrils promoted cellular interactions. Characterizations of the system revealed a thermally induced fibril disassembly and reassembly pathway that facilitated the complexation of the fibrils with the cells. Using the nanofibrils of varied stabilities, the cell-cell interaction was promoted to different extents with free-to-bound cell conversion ratios achieved at low (31%), medium (54%), and high (93%) levels. This study expands the toolbox to generate desired cell behaviors for applications in many areas and highlights the merits of thermally less stable nanoassemblies in designing functional materials.

Artemeriosides A-F, the first examples of natural sesquiterpenoids substituted by a 6'-O-crontonyl ß-glucopyranoside from Artemisia annua.

Artemeriosides A-F (1-6), six novel sesquiterpenoids containing a 6'-O-crontonyl ß-glucopyranoside, were isolated from Artemisia annua L. Their structures were determined by spectral data including HRESIMS, IR, UV, 1D and 2D NMR, and ECD calculations. Compounds 1-6 represented the first examples of natural sesquiterpenoid substituted by 6'-O-crontonyl ß-glucopyranoside. By antihepatoma assay, compounds 1 and 2 demonstrated inhibitory effect against both HepG2 and SK-Hep-1 cells with inhibitory ratios of 77.0%, 88.8%, and 86.8%, 83.9% at 200.0 µM, and compound 1 showed inhibitory activity against Huh7 cells with inhibitory ratio of 56.8%.

Amyloid peptide hydrogels via formation of coordination polymers with Ag+ by its core peptide equipped with a C-cysteine.

We report that the core sequence of amyloid ß (Aß) peptide, KLVFF, when equipped with a C-terminal cysteine residue, exhibited an extremely low minimum hydrogelation concentration of 0.05 wt% in the presence of Ag+ in pH 5 buffer, with this concentration 2 orders of magnitude lower than that of the pentapeptide itself. The CD signal of the Ag+-L-KLVFFC hydrogel was observed to be sensitive to the early-stage aggregation of amyloid ß peptide.

Design, synthesis, and biological evaluation of artemyrianolide H derivatives as potential antihepatoma agents.

Artemyrianolide H (AH) is a germacrene-type sesquiterpenolid isolated from Artemisia myriantha, and showed potent cytotoxicity against three human hepatocellular carcinoma cell lines HepG2, Huh7, and SK-Hep-1 with IC50 values of 10.9, 7.2, and 11.9 µM, respectively. To reveal structure-activity relationship, 51 artemyrianolide H derivatives including 19 dimeric analogs were designed, synthesized, and assayed for their cytotoxicity against three human hepatoma cell lines. Among them, 34 compounds were more active than artemyrianolide H and sorafenib on the three cell lines. Especially, compound 25 exhibited the most promising activity with IC50 values of 0.7 (HepG2), 0.6 (Huh7), and 1.3 µM (SK-Hep-1), which were 15.5, 12.0, and 9.2-fold higher than that of AH and 16.4, 16.3 and 17.5-fold higher than that of sorafenib. Cytotoxicity evaluation on normal human liver cell lines (THLE-2) demonstrated good safety profile of compound 25 with SI of 1.9 (HepG2), 2.2 (Huh 7) and 1.0 (SK-Hep1). Further studies revealed that compound 25 dose-dependently arrested cells at G2/M phase which was correlated with the up-regulation of both cyclin B1 and p-CDK1, and induced apoptosis through the activation of mitochondrial pathways in HepG2 cells. In addition, the migratory and invasive abilities in HepG2 cells after treatment with 1.5 µM of compound 25 were decreased by 89% and 86% with the increase of E-cadherin expression accompanied by the decrease of N-cadherin, vimentin expression. Bioinformatics analysis based on machine learning predicted that PDGFRA and MAP2K2 might be acting targets of compound 25, and SPR assays demonstrated compound 25 were bound with PDGFRA and MAP2K2 with KD value of 0.168 nM, and 8.49 µM, respectively. This investigation proposed that compound 25 might be considered as a promising lead compound for the development of antihepatoma candidate.

Artemannuols A-C, novel sesquiterpenoid-flavonol hybrids with antihepatoma activity from Artemisia annua.

Artemisia annua, also known as "Qinghao" in Chinese, is a famous traditional Chinese medicine and has been used for the treatment of malaria and various tumors. In this study, three novel sesquiterpenoid-flavonol hybrids, artemannuols A-C (1-3), were isolated and elucidated by extensive spectral data and ECD calculations. Structurally, artemannuols A-C (1-3) are the first examples of sesquiterpenoid-flavonol hybrids fused by an ether bond, among which artemannuols A and B (1 and 2) are composed of bisabolane-type sesquiterpenoid and flavonol moieties, and artemannuol C (3) is composed of humulane-type sesquiterpenoid and flavonol moieties. The antihepatoma assay suggested that compounds 1-3 showed inhibitory effects against HepG2, Huh7, and SK-Hep-1 cell lines with IC50 values in the range of 32.7 to 70.4 µM.

Design and synthesis of guaianolide-germacranolide heterodimers as novel anticancer agents against hepatocellular carcinoma.

Inspired by our previous finding that disesquiterpenoids showed more potent antihepatoma cytotoxicity than their corresponding parent monomers, natural product-like guaianolide-germacranolide heterodimers were designed and synthesized from guaianolide diene and germacranolides via a biomimetic Diels-Alder reaction to provide three antihepatoma active dimers with novel scaffolds. To explore the structure-activity relationship, 31 derivatives containing ester, carbamate, ether, urea, amide, and triazole functional groups at C-14' were synthesized and evaluated for their cytotoxic activities against HepG2, Huh7, and SK-Hep-1 cell lines. Among them, 25 compounds were more potent than sorafenib against HepG2 cells, 15 compounds were stronger than sorafenib against Huh7 cells, and 17 compounds were stronger than sorafenib against SK-Hep-1 cells. Compound 23 showed the most potent cytotoxicity against three hepatoma cell lines with IC50 values of 4.4 µM (HepG2), 3.7 µM (Huh7), and 3.1 µM (SK-Hep-1), which were 2.7-, 2.2-, and 2.8-fold more potent than sorafenib, respectively. The underlying mechanism study demonstrated that compound 23 could induce cell apoptosis, prevent cell migration and invasion, cause G2/M phase arrest in SK-Hep-1 cells. Network pharmacology analyses predicted PDGFRA was one of the potential targets of compound 23, and surface plasmon resonance (SPR) assay verified that 23 had strong affinity with PDGFRA with a dissociatin constant (KD) value of 90.2 nM. These promising findings revealed that structurally novel guaianolide-germacranolide heterodimers might provide a new inspiration for the discovery of antihepatoma agents.

Artemiprinolides A-M, thirteen undescribed sesquiterpenoid dimers from Artemisia princeps and their antihepatoma activity.

Bioassay-guided investigation of the active fraction of Artemisia princeps led to 13 undescribed sesquiterpenoid dimers, artemiprinolides A-M (1-13), together with 11 known ones (14-24). Their structures were elucidated by comprehensive spectroscopic data and absolute configurations were assigned based on single crystal X-ray diffraction data and ECD calculations. Structurally, all compounds were postulated to be derived from the Diels-Alder cycloaddition. The isolated dimers except 11 and 15 were assayed for their cytotoxicity against HepG2, Huh7, and SK-Hep-1 cell lines, of which four compounds (3, 13, 17, 18) exhibited obvious cytotoxicity with IC50 values ranging from 8.8 to 20.1 µM. Interestingly, the most active compounds 1 and 16 manifested significant cytotoxicity on the three tested hepatoma cell lines with IC50 values of 5.4, 4.1 (HepG2), 7.7, 5.6 (Huh7), and 11.8, 15.7 µM (SK-Hep-1), respectively, which were better than sorafenib. Compound 1 dose-dependently inhibited cell migration and invasion, and significantly induced the HepG2 cell arrest in G2/M phase by downregulating cdc2 and pcdc2 and upregulating cyclinB1; and induced apoptosis by downregulating Bcl-2 expression and upregulating Bax level. The molecular docking study implied that the carbonyl at the C-12' of 1 had a strong binding affinity with PRKACA.

One-Pot Cyclization to Large Peptidomimetic Macrocycles by In Situ-Generated ß-Turn-Enforced Folding.

Macrocycles have been targets of extensive synthetic efforts for decades because of their potent molecular recognition and self-assembly capabilities. Yet, efficient syntheses of macrocyclic molecules via irreversible covalent bonds remain challenging. Here, we report an efficient approach to large peptidomimetic macrocycles by using the in situ-generated ß-turn structural motifs afforded in the amidothiourea moieties from the early steps of the reaction of 2 molecules of bilateral amino acid-based acylhydrazine with 2 molecules of diisothiocyanate. Four chiral and achiral peptidomimetic large macrocycles were successfully synthesized in high yields of 45-63% in a feasible one-pot reaction under sub-molar concentration conditions and were purified by simple filtration. X-ray crystallographic characterization of three macrocycles reveals an important feature that their four ß-turn structures, each maintained by four 10-membered intramolecular hydrogen bonds, alternatively network the four aromatic arms. This affords an interesting conformation switching mode upon anion binding. Binding of SO42- to 1L or 1D that contains 4 alanine residues (with the lowest steric hinderance among the macrocycles) leads to an inside-out structural change of the host macrocycle, as confirmed by the X-ray crystal structure of 1L-SO42- and 1D-SO42- complexes, accompanied by an inversion of the CD signals. On the basis of the strong sulfate affinity of the macrocycles, we succeeded in the removal of sulfate anions from water via a macrocycle-mediated liquid-liquid extraction method. Our synthetic protocol can be easily extended to other macrocycles of varying arms and/or chiral amino acid residues; thus, a variety of structurally and functionally diverse macrocycles are expected to be readily made.

[Chemical constituents from leaves of Craibiodendron yunnanense].

The present study investigated the chemical constituents from the leaves of Craibiodendron yunnanense. The compounds were isolated and purified from the leaves of C. yunnanense by a combination of various chromatographic techniques including column chromatography over polyamide, silica gel, Sephadex LH-20, and reversed-phase HPLC. Their structures were identified by extensive spectroscopic analyses including MS and NMR data. As a result, 10 compounds, including melionoside F(1), meliosmaionol D(2), naringenin(3), quercetin-3-O-α-L-arabinopyranoside(4), epicatechin(5), quercetin-3'-glucoside(6), corbulain Ib(7), loliolide(8), asiatic acid(9), and ursolic acid(10), were isolated. Compounds 1 and 2 were two new compounds, and compound 7 was isolated from this genus for the first time. All compounds showed no significant cytotoxic activity by MTT assay.

Muyocoxanthones O-S: Undescribed xanthones with antioxidative damage bioactivity to cardiomyocytes from the endophytic fungus Muyocopron laterale.

The metabolites from the endophytic fungus Muyocopron laterale hosted in the medicinal plant Tylophora ovata were investigated, and five undescribed xanthones, muyocoxanthones O-S, along with seven known compounds were isolated. Their structures were elucidated by HR-ESI-MS, NMR, and ECD calculations. Compounds were evaluated for their anti-cardiomyocyte oxidative damage activity using a model of oxidative damage induced by cell hypoxia incubation. Muyocoxanthones O-Q and blennolide L exhibited moderate activity against oxidative damage to cardiomyocytes with relative viabilities of 62.4, 54.8, 60.3 and 54.9%, respectively.