Asymmetric total synthesis of polycyclic xanthenes and discovery of a WalK activator active against MRSA.

The development of new antibiotics continues to pose challenges, particularly considering the growing threat of multidrug-resistant Staphylococcus aureus. Structurally diverse natural products provide a promising source of antibiotics. Herein, we outline a concise approach for the collective asymmetric total synthesis of polycyclic xanthene myrtucommulone D and five related congeners. The strategy involves rapid assembly of the challenging benzopyrano[2,3-a]xanthene core, highly diastereoselective establishment of three contiguous stereocenters through a retro-hemiketalization/double Michael cascade reaction, and a Mitsunobu-mediated chiral resolution approach with high optical purity and broad substrate scope. Quantum mechanical calculations provide insight into stereoselective construction mechanism of the three contiguous stereocenters. Additionally, this work leads to the discovery of an antibacterial agent against both drug-sensitive and drug-resistant S. aureus. This compound operates through a unique mechanism that promotes bacterial autolysis by activating the two-component sensory histidine kinase WalK. Our research holds potential for future antibacterial drug development.

Antiviral C-geranylated flavonoids from Artocarpus communis.

Ten C-geranylated flavonoids, along with three known analogues, were isolated from the leaves of Artocarpus communis. The chemical structures of these compounds were unambiguously determined via comprehensive spectroscopic analysis, single-crystal X-ray diffraction experiments, and quantum chemical electronic circular dichroism calculations. Structurally, artocarones A-I (1-9) represent a group of unusual, highly modified C-geranylated flavonoids, in which the geranyl chain is cyclised with the ortho-hydroxy group of flavonoids to form various heterocyclic scaffolds. Notably, artocarones E and G-I (5 and 7-9) feature a 6H-benzo[c]chromene core that is hitherto undescribed in C-geranylated flavonoids. Artocarone J (10) is the first example of C-9-C-16 connected C-geranylated aurone. Meanwhile, the plausible biosynthetic pathways for these rare C-geranylated flavonoids were also proposed. Notably, compounds 1, 2, 4, 8, 11, and 12 exhibited promising in vitro inhibitory activities against respiratory syncytial virus and herpes simplex virus type 1.

Anti-inflammatory naphthoquinone-monoterpene adducts and neolignans from Eugenia caryophyllata.

A phytochemical investigation on the buds of edible medicinal plant, Eugenia carvophyllata, led to the discovery of seven new compounds, caryophones A-G (1-7), along with two biogenetically-related known ones, 2-methoxy-7-methyl-1,4-naphthalenedione (8) and eugenol (9). Compounds 1-3 represent the first examples of C-5-C-1' connected naphthoquinone-monoterpene adducts with a new carbon skeleton. Compounds 4-7 are a class of novel neolignans with unusual linkage patterns, in which the C-9 position of one phenylpropene unit coupled with the aromatic core of another phenylpropene unit. The chemical structures of the new compounds were determined based on extensive spectroscopic analysis, X-ray diffraction crystallography, and quantum-chemical calculation. Among the isolates, compounds (-)-2, 3, 6, and 9 showed significant in vitro inhibitory activities against respiratory syncytial virus (RSV)-induced nitric oxide (NO) production in RAW264.7 cells.

[Two new benzoyl-sesquiterpenes from Mesona chinensis].

Mesona chinensis is a common medicinal and edible plant in the Lingnan region of China, which has extensive pharmacological activity. However, the study of its chemical constituents is not sufficient. In this study, a variety of modern chromatographic separation techniques were used to isolate two compounds from 95% ethanol extract of the grass parts of M. chinensis. Their absolute configurations were determined by ultraviolet spectroscopy(UV), infrared spectroscopy(IR), high resolution mass spectrometry(HR-ESI-MS), 1D and 2D nuclear magnetic resonance(1D NMR and 2D NMR), and single-crystal X-ray diffraction(SC-XRD). Specifically, they were two new benzoyl-sesquiterpenes and named mesonanol A and mesonanol B, respectively. The results of the pharmacological activity evaluation showed that neither of the two new compounds showed obvious antiviral and anti-inflammatory activities.

Targeting FAPα-positive lymph node metastatic tumor cells suppresses colorectal cancer metastasis.

Lymphatic metastasis is the main metastatic route for colorectal cancer, which increases the risk of cancer recurrence and distant metastasis. The properties of the lymph node metastatic colorectal cancer (LNM-CRC) cells are poorly understood, and effective therapies are still lacking. Here, we found that hypoxia-induced fibroblast activation protein alpha (FAPα) expression in LNM-CRC cells. Gain- or loss-function experiments demonstrated that FAPα enhanced tumor cell migration, invasion, epithelial-mesenchymal transition, stemness, and lymphangiogenesis via activation of the STAT3 pathway. In addition, FAPα in tumor cells induced extracellular matrix remodeling and established an immunosuppressive environment via recruiting regulatory T cells, to promote colorectal cancer lymph node metastasis (CRCLNM). Z-GP-DAVLBH, a FAPα-activated prodrug, inhibited CRCLNM by targeting FAPα-positive LNM-CRC cells. Our study highlights the role of FAPα in tumor cells in CRCLNM and provides a potential therapeutic target and promising strategy for CRCLNM.

Tautomeric cinnamoylphloroglucinol-monoterpene adducts from Cleistocalyx operculatus and their antiviral activities.

Guided by 1H NMR spectroscopic experiments using the characteristic enol proton signals as probes, three pairs of new tautomeric cinnamoylphloroglucinol-monoterpene adducts (1-3) were isolated from the buds of Cleistocalyx operculatus. Their structures with absolute configurations were established by spectroscopic analysis, modified Mosher's method, and quantum chemical electronic circular dichroism calculation. Compounds 1-3 represent a novel class of cinnamoylphloroglucinol-monoterpene adducts featuring an unusual C-4-C-1' linkage between 2,2,4-trimethyl-cinnamyl-ß-triketone and modified linear monoterpenoid motifs. Notably, compounds 1-3 exhibited significant in vitro antiviral activity against respiratory syncytial virus (RSV).

Kaempferol-3-O-sophoroside (PCS-1) contributes to modulation of depressive-like behaviour in C57BL/6J mice by activating AMPK.

BACKGROUND AND PURPOSE: Kaempferol-3-O-sophoroside (PCS-1) is the main component in Crocus sativus (Saffron), a herb with mood-enhancing properties. AMP-activated protein kinase (AMPK) is a potential therapeutic target for depression. This study explores the antidepressive-like properties of PCS-1 and its AMPK activation to confirm AMPK as a target for antidepression. EXPERIMENTAL APPROACH: Corticosterone (CORT)-induced PC12 cell injury served as an in vitro model to evaluate the neuroprotective effect of PCS-1. Neuro-2a cells and primary neurons were utilized to evaluate the synaptogenesis role of PCS-1. CORT-induced mouse depression model and chronic unpredictable mild stress (CUMS) model were used to assess the antidepressive-like properties of PCS-1 through behavioural tests, magnetic resonance imaging, and biochemical index measurements. Western blot and immunofluorescence assays were used to study the mechanisms of PCS-1. Cellular thermal shift assay was used to confirm the binding target. KEY RESULTS: PCS-1 (12.5-50 µM) ameliorated CORT-induced PC12 cell damage, oxidative stress and inflammation. PCS-1 alone promoted an increase in synapses in Neuro-2a cells and primary neurons. Oral administration of PCS-1 (10 and 20 mg·kg-1 ) ameliorated weight loss, dyskinesia, and hippocampal volume reduction induced by CORT and CUMS. PCS-1 bound to AMPK to improve the expression of brain-derived neurotrophic factor (BDNF) and induce autophagy. CONCLUSION AND IMPLICATIONS: PCS-1 binds to AMPK to promote BDNF production and autophagy enhancement, ultimately achieving antidepressant effects. This study provides support for the clinical application of saffron petals and provides further evidence for AMPK as a potential target for antidepression.

Discovery of Unusual Ajmaline-Macroline Type Bisindole Alkaloids from Alstonia macrophylla by Building Blocks-Based Molecular Networking.

Three unusual ajmaline-macroline type bisindole alkaloids, alsmaphylines A-C, together with their postulated biogenetic precursors, were isolated from the stem barks and leaves of Alstonia macrophylla via the building blocks-based molecular network (BBMN) strategy. Alsmaphyline A represents a rare ajmaline-macroline type bisindole alkaloid with an S-shape polycyclic ring system. Alsmaphylines B and C are two novel ajmaline-macroline type bisindole alkaloids with N-1-C-21' linkages, and the former possesses an unconventional stacked conformation due to the presence of intramolecular noncovalent interactions. The chemical structures including absolute configurations of alsmaphylines A-C were established by comprehensive spectroscopic analyses, electronic circular dichroism (ECD) calculations, and single-crystal X-ray crystallography. In addition, a plausible biosynthetic pathway of these bisindole alkaloids as well as their ability to promote the protein synthesis on HT22 cells were discussed.

Characteristic chromanone acids from Calophyllum membranaceum: Determination of C-3 configuration and anti-inflammatory activity.

One undescribed homologous furanochromanone (1) featuring a 6/6/5/3 tetracyclic skeleton and four highly oxidized pyranochromanones (2-5), along with a set of four pyranochromanone stereoisomers [(±)-6a and (±)-6b], were isolated from the leaves of Calophyllum membranaceum Gardn. Et Champ. Their structures were elucidated by using spectroscopic data, Snatzke's method, quantum-chemical calculations, and X-ray crystallographic analysis. The correlation of characteristic Cotton effects and specific chemical shifts with C-3 configuration provided a convenient approach to assign the C-3 configuration of 2,3-dimethylchromanones. The stereochemical assignments of 3-OH substituted pyranochromanones by quantum-based NMR methods following single/double MTPA derivatization were consistent with the ECD/NMR prediction, which verified the feasibility and reliability of the proposed empirical rule. The underlying mechanism was further clarified by conformational and molecular orbital analyses. Moreover, biological evaluation and binding assays demonstrated that compound 3 (KD = 0.45 µM) tightly binds to the TLR4-MD2 target, thereby inhibiting the TLR4/MyD88-dependent and -independent signal pathways. This study provides the first evidence that Calophyllum chromanones are a novel structural type of TLR4 inhibitors, exerting their anti-inflammatory effects by disrupting the binding between TLR4 and MD2.

Beauvericin suppresses the proliferation and pulmonary metastasis of osteosarcoma by selectively inhibiting TGFBR2 pathway.

Osteosarcoma (OS) patients, particularly those with distant metastasis, experience rapid progression and derive poor survival benefits from traditional therapies. Currently, effective drugs for treating patients with metastatic OS remain scarce. Here, we found that the cyclic hexadepsipeptide beauvericin (BEA) functioned as a new selective TGFBR2 inhibitor with potent antiproliferative and antimetastatic activities against OS cells. Functionally, BEA inhibited TGF-ß signaling-mediated proliferation, invasiveness, mesenchymal phenotype, and extracellular matrix remodeling of OS cells, and suppressed tumor growth and reduced pulmonary metastasis in vivo. Mechanistic investigation revealed that BEA selectively and directly bound to Asn 332 of TGFBR2 and inhibited its kinase activity, thereby suppressing the aggressive progression of OS cells. Together, our study identifies an innovative and natural selective TGFBR2 inhibitor with effective antineoplastic activity against metastatic OS and demonstrates that targeting TGFBR2 could be a potential therapeutic strategy for metastatic OS.

Biomimetic Synthesis of an Antiviral Cinnamoylphloroglucinol Collection from Cleistocalyx operculatus: A Synthetic Strategy Based on Biogenetic Building Blocks.

A synthetic strategy based on biogenetic building blocks for the collective and divergent biomimetic synthesis of cleistoperlones A-F, a cinnamoylphloroglucinol collection discovered from Cleistocalyx operculatus, has been developed. These syntheses proceeded successfully in only six to seven steps starting from commercially available 1,3,5-benzenetriol and involving oxidative activation of stable biogenetic building blocks as a crucial step. Key features of the syntheses include a unique Michael addition/ketalization/1,6-addition/enol-keto tautomerism cascade reaction for the construction of the dihydropyrano[3,2-d]xanthene tetracyclic core of cleistoperlones A and B, and a rare inverse-electron-demand hetero-Diels-Alder cycloaddition for the establishment of benzopyran ring in cleistoperlones D-F. Moreover, cleistoperlone A exhibited significant antiviral activity against acyclovir-resistant strains of herpes simplex virus type 1 (HSV-1/Blue and HSV-1/153).

Secoiridoid glycosides from the fruits of Ligustrum lucidum and their in vitro anti-inflammatory activity.

Seven new secoiridoid glycosides (1-7), together with a known analogue (8), were isolated from the fruits of Ligustrum lucidum. Their structures with absolute configurations were determined by HR-ESI-MS, 1D and 2D NMR, and electronic circular dichroism (ECD) spectroscopic analysis, as well as biogenetic consideration. Compounds 1 and 2 are the first examples of secoiridoid glycoside dimers featuring a rare rearranged oleoside-type secoiridoid moiety, and compounds 3-7 represent a new class of oleoside-type secoiridoid glycosides with unusual stereochemistry at C-1 position. A plausible biosynthetic pathway for this group of unusual secoiridoid glycosides was also proposed herein. In addition, the isolates were evaluated for their in vitro anti-inflammatory activity, and all tested compounds exhibited modest inhibitory effects against nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW264.7 macrophages.

ENO2-derived phosphoenolpyruvate functions as an endogenous inhibitor of HDAC1 and confers resistance to antiangiogenic therapy.

Metabolic reprogramming is associated with resistance to antiangiogenic therapy in cancer. However, its molecular mechanisms have not been clearly elucidated. Here, we identify the glycolytic enzyme enolase 2 (ENO2) as a driver of resistance to antiangiogenic therapy in colorectal cancer (CRC) mouse models and human participants. ENO2 overexpression induces neuroendocrine differentiation, promotes malignant behaviour in CRC and desensitizes CRC to antiangiogenic drugs. Mechanistically, the ENO2-derived metabolite phosphoenolpyruvate (PEP) selectively inhibits histone deacetylase 1 (HDAC1) activity, which increases the acetylation of ß-catenin and activates the ß-catenin pathway in CRC. Inhibition of ENO2 with enolase inhibitors AP-III-a4 or POMHEX synergizes the efficacy of antiangiogenic drugs in vitro and in mice bearing drug-resistant CRC xenograft tumours. Together, our findings reveal that ENO2 constitutes a useful predictive biomarker and therapeutic target for resistance to antiangiogenic therapy in CRC, and uncover a previously undefined and metabolism-independent role of PEP in regulating resistance to antiangiogenic therapy by functioning as an endogenous HDAC1 inhibitor.

Limonoids from the roots of Melia azedarach and their anti-inflammatory activity.

Twelve undescribed limonoids, meliazedarines J-U (1-12), along with a known one, were isolated from the roots of Melia azedarach. Their structures were elucidated by extensive spectroscopic investigations, X-ray diffraction analyses, and ECD calculations. Compounds 1-8 were identified as ring intact limonoids, while compounds 9-12 were established as ring C-seco ones. The anti-inflammatory potential of compounds 1-4, 6, 8, 9, and 11-13 was evaluated on macrophages. Compounds 1, 3, 4, 6, and 9 significantly suppressed nitric oxide production in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages, among them compound 3 showed the best inhibitory effect with an IC50 value of 7.07 ± 0.48 µΜ. Furthermore, compound 3 effectively reduced interleukin-1ß secretion in LPS plus nigericin-induced THP-1 macrophages by inhibiting NLRP3 inflammasome activation. The results strongly suggested that limonoids from the roots of M. azedarach might be candidates for treating inflammation-related diseases.

TCAF2 in Pericytes Promotes Colorectal Cancer Liver Metastasis via Inhibiting Cold-Sensing TRPM8 Channel.

Hematogenous metastasis is the main approach for colorectal cancer liver metastasis (CRCLM). However, as the gatekeepers in the tumor vessels, the role of TPCs in hematogenous metastasis remains largely unknown, which may be attributed to the lack of specific biomarkers for TPC isolation. Here, microdissection combined with a pericyte medium-based approach is developed to obtain TPCs from CRC patients. Proteomic analysis reveals that TRP channel-associated factor 2 (TCAF2), a partner protein of the transient receptor potential cation channel subfamily M member 8 (TRPM8), is overexpressed in TPCs from patients with CRCLM. TCAF2 in TPCs is correlated with liver metastasis, short overall survival, and disease-free survival in CRC patients. Gain- and loss-of-function experiments validate that TCAF2 in TPCs promotes tumor cell motility, epithelial-mesenchymal transition (EMT), and CRCLM, which is attenuated in pericyte-conditional Tcaf2-knockout mice. Mechanistically, TCAF2 inhibits the expression and activity of TRPM8, leading to Wnt5a secretion in TPCs, which facilitates EMT via the activation of the STAT3 signaling pathway in tumor cells. Menthol, a TRPM8 agonist, significantly suppresses Wnt5a secretion in TPCs and CRCLM. This study reveals the previously unidentified pro-metastatic effects of TPCs from the perspective of cold-sensory receptors, providing a promising diagnostic biomarker and therapeutic target for CRCLM.

Regulation of toll-like receptor (TLR) signaling pathways in atherosclerosis: from mechanisms to targeted therapeutics.

Atherosclerosis, one of the life-threatening cardiovascular diseases (CVDs), has been demonstrated to be a chronic inflammatory disease, and inflammatory and immune processes are involved in the origin and development of the disease. Toll-like receptors (TLRs), a class of pattern recognition receptors that trigger innate immune responses by identifying pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs), regulate numerous acute and chronic inflammatory diseases. Recent studies reveal that TLRs have a vital role in the occurrence and development of atherosclerosis, including the initiation of endothelial dysfunction, interaction of various immune cells, and activation of a number of other inflammatory pathways. We herein summarize some other inflammatory signaling pathways, protein molecules, and cellular responses associated with TLRs, such as NLRP3, Nrf2, PCSK9, autophagy, pyroptosis and necroptosis, which are also involved in the development of AS. Targeting TLRs and their regulated inflammatory events could be a promising new strategy for the treatment of atherosclerotic CVDs. Novel drugs that exert therapeutic effects on AS through TLRs and their related pathways are increasingly being developed. In this article, we comprehensively review the current knowledge of TLR signaling pathways in atherosclerosis and actively seek potential therapeutic strategies using TLRs as a breakthrough point in the prevention and therapy of atherosclerosis.

Zoledronic acid and thymosin α1 elicit antitumor immunity against prostate cancer by enhancing tumor inflammation and cytotoxic T cells.

BACKGROUND: Advanced or metastatic prostate cancer (PCa) is still an incurable malignancy with high lethality and a poor prognosis. Despite the remarkable success of immunotherapy against many types of cancer, most patients with PCa receive minimal benefit from current immunotherapeutic strategies, because PCa is an immune cold tumor with scarce T-cell infiltration in the tumor microenvironment. The aim of this study was to develop an effective immunotherapeutic approach for immune cold PCa tumors. METHODS: The therapeutic efficacy of androgen deprivation therapy (ADT) and zoledronic acid (ZA) plus thymosin α1 (Tα1) therapy was analyzed retrospectively in patients with advanced or metastatic PCa. The effects and mechanisms by which ZA and Tα1 regulated the immune functions of PCa cells and immune cells were evaluated by a PCa allograft mouse model, flow cytometric analysis, immunohistochemical and immunofluorescence staining assays, and PCR, ELISA, and Western blot analyses. RESULTS: In this study, clinical retrospective analysis revealed that ADT combined with ZA plus Tα1 improved the therapeutic outcomes of patients with PCa, which might be associated with an enhanced frequency of T cells. ZA and Tα1 treatment synergistically inhibited the growth of androgen-independent PCa allograft tumors, with increased infiltration of tumor-specific cytotoxic CD8+ T cells and enhanced tumor inflammation. Functionally, ZA and Tα1 treatment relieved immunosuppression in PCa cells, stimulated pro-inflammatory macrophages, and enhanced the cytotoxic function of T cells. Mechanistically, ZA plus Tα1 therapy blocked the MyD88/NF-κB pathway in PCa cells but activated this signaling in macrophages and T cells, altering the tumor immune landscape to suppress PCa progression. CONCLUSIONS: These findings uncover a previously undefined role for ZA and Tα1 in inhibiting the disease progression of immune cold PCa tumors by enhancing antitumor immunity and pave the way for the application of ZA plus Tα1 therapy as an immunotherapeutic strategy for treating patients with immunologically unresponsive PCa.

lncRNA SYTL5-OT4 promotes vessel co-option by inhibiting the autophagic degradation of ASCT2.

AIMS: Vessel co-option is responsible for tumor resistance to antiangiogenic therapies (AATs) in patients with colorectal cancer liver metastasis (CRCLM). However, the mechanisms underlying vessel co-option remain largely unknown. Herein, we investigated the roles of a novel lncRNA SYTL5-OT4 and Alanine-Serine-Cysteine Transporter 2 (ASCT2) in vessel co-option-mediated AAT resistance. METHODS: SYTL5-OT4 was identified by RNA-sequencing and verified by RT-qPCR and RNA fluorescence in situ hybridization assays. The effects of SYTL5-OT4 and ASCT2 on tumor cells were investigated by gain- and loss-of-function experiments, and those of SYTL5-OT4 on ASCT2 expression were analyzed by RNA immunoprecipitation and co-immunoprecipitation assays. The roles of SYTL5-OT4 and ASCT2 in vessel co-option were detected by histological, immunohistochemical, and immunofluorescence analyses. RESULTS: The expression of SYTL5-OT4 and ASCT2 was higher in patients with AAT-resistant CRCLM. SYTL5-OT4 enhanced the expression of ASCT2 by inhibiting its autophagic degradation. SYTL5-OT4 and ASCT2 promoted vessel co-option by increasing the proliferation and epithelial-mesenchymal transition of tumor cells. Combination therapy of ASCT2 inhibitor and antiangiogenic agents overcame vessel co-option-mediated AAT resistance in CRCLM. CONCLUSION: This study highlights the crucial roles of lncRNA and glutamine metabolism in vessel co-option and provides a potential therapeutic strategy for patients with AAT-resistant CRCLM.