Journal of Natural Products 最新文献

Wheldone is a fungal metabolite isolated from the coculture of Aspergillus fischeri and Xylaria flabelliformis, displaying cytotoxic activity against breast, melanoma, and ovarian cancer cell lines. Initially, its structure was characterized as an unusual 5-methyl-bicyclo[5.4.0]undeca-3,5-diene scaffold with a 2-hydroxy-1-propanone side chain and a 3-(2-(1-hydroxyethyl)-2-methyl-2,5-dihydrofuran-3-yl)acrylic acid moiety. Upon further examination, minor inconsistencies in the data suggested the need for the structure to be revisited. Thus, the structure of wheldone has been revised using an orthogonal experimental-computational approach, which combines 1,1-HD-ADEQUATE NMR experiments, DFT-GIAO chemical shift calculations, and single-crystal X-ray diffraction (SCXRD) analysis of a semisynthetic p-bromobenzylamide derivative, formed via a Steglich-type reaction. The summation of these data now permits the unequivocal assignment of both the structure and absolute configuration of the natural product.

Hepatocellular carcinoma (HCC) is an aggressive cancer that has an effect on human health. As a first-line drug for HCC, despite its excellent efficacy, lenvatinib (Len) is prone to developing drug resistance in HCC patients. The N6-methyladenosine (m6A) modification is not only related to the development of HCC but also shows great potential in overcoming HCC resistance. Using Dot Blot, our group first screened a small molecule m6A regulator, lobeline (Lob), from a library of 390 compounds (mostly natural products). In vitro experiments demonstrated that Lob could significantly enhance the sensitivity to Len of Len-resistant HCC (HCC/Len) and inhibit migration of resistant cells. In Len-resistant cell-derived and patient-derived xenograft models, Lob could reverse the resistant phenotype, with reductions in tumor volume of 68% and 60%, respectively. Furthermore, MeRIP-m6A sequencing results indicated that the underlying molecular mechanism of Lob reversal of HCC drug resistance was related to UBE3B. Taken together, this study highlighted that Lob, a plant derived natural product, could reverse the resistance of HCC to Len by regulating the m6A levels. It is hoped that this will provide a pharmacological research basis for the clinical treatment of HCC patients.

In the search of new inhibitors for human coronavirus (HCoV), we screened extracts of endemic Annonaceae plants on an assay using a cellular model of Huh-7 cells infected with the human alphacoronavirus HCoV-229E. The EtOAc bark extract of the rare Southeast Asian plant Neo-uvaria foetida exhibited inhibition of HCoV-229E and SARS-CoV-2 viruses with IC₅₀ values of 3.8 and 7.8 μg/mL, respectively. Using LC-MS/MS and molecular networking analysis guided isolation, we discovered two new labdane-type diterpenoids, 8-epi-acuminolide (1) and foetidalabdane A (4), and three known labdane diterpenoids, acuminolide (2), 17-O-acetylacuminolide (3), and spiroacuminolide (5). A new norlabdane diterpene, 16-foetinorlabdoic acid (6), was also isolated and identified. Excluding compounds 5 and 6, all other metabolites were active against the virus HCoV-229E. Terpenoids 1 and 4 presented antiviral activity against SARS-CoV-2 with IC₅₀ values of 63.3 and 93.5 μM, respectively, indicating lower potency. Additionally, virological assays demonstrated that compounds 1, 2, and 3 exert antiviral effects against Zika virus by specifically interfering with the late stage of its infectious cycle with IC₅₀ values of 76.0, 31.9, and 14.9 μM, respectively.

Seven new formononetin derivatives (1-7) were designed and prepared from formononetin (phase II phytoestrogen). The derivatives 9-butyl-3-(4-methoxyphenyl)-9,10-dihydro-4H,8H-chromeno[8,7-e][1,3]oxazin-4-one (2) and 9-(furan-3-ylmethyl)-3-(4-methoxyphenyl)-9,10-dihydro-4H,8H-chromeno[8,7-e][1,3]oxazin-4-one (7) promoted significant osteoblast formation by modulating the BMP/Smad pathway. Compound 7 exhibited potent antiosteoclastogenesis activity in RANKL-induced RAW264.7 cells and ovariectomy (OVX)-induced osteoporosis in mice by regulation of the RANK/RANKL/OPG pathway. Compound 7 regulated osteoblast and osteoclast simultaneously and showed better effect than the well-known drug ipriflavone in vivo, suggesting 7 as a patented antiosteoporosis candidate.

Portimine B was isolated from an extract derived from the dinoflagellate Vulcanodinium rugosum, a known producer of the closely related portimine A. Initial molecular characterization studies of portimine B suggested an open tetrahydrofuranyl ring isomer, contrary to the intact ring moiety found in portimine A. In 2023, the Baran lab synthesized both portimines A and B suggesting that both macrocyclic analogs contained the intact tetrahydrofuranyl ring. In this note, we utilize newly acquired NMR data, the i-HMBC NMR experiment, and advanced density functional theory calculations to define the structural divergence, originating from the presence of a transient hydrate.

The development of tuberculosis (TB) therapy has been marked by the discovery of natural-product-derived streptomycin, followed by the introduction of NP-derived rifampicin, representing a significant milestone in the history of TB management. However, TB remains a global challenge, with the emergence of multidrug-resistant Mycobacterium tuberculosis highlighting the need for novel therapeutic agents. In this study, a bioinformatic approach was employed to investigate d-amino acid-activating adenylation domains, leading to the identification of cordysetin A (1), a novel trans-decalin tetramic acid antibiotic from the ascomycete fungi Cordyceps militaris. Cordysetin A (1) exhibits considerable activity against M. tuberculosis in vitro and in vivo while maintaining low cytotoxicity. These results reveal that the d-configuration of the amino acid within this hybrid polyketide-nonribosomal antibiotic is crucial for preserving its anti-tuberculosis efficacy. These findings emphasize the significant translational potential of cordysetin A as a promising candidate for TB treatment, furthering our understanding of bioinformatic approaches in the development of effective anti-tuberculosis agents.

Four new compounds, racemic chalcone-monoterpene hybrids (1-3) and a chalcone (9), along with nine known compounds (4-8, 10-13), have been isolated from the buds of Cleistocalyx operculatus. The chemical structures of the isolated compounds were identified through NMR data analysis and confirmed by computational methods, including electronic circular dichroism (ECD) calculations, and further synthetic approaches. Compounds 1-5 were synthesized via a Diels-Alder reaction, a process informed by biomimetic condensation studies that combined chalcones and monoterpenes. These synthetic approaches also yielded various unnatural chalcone-monoterpene derivatives (14-23). The inhibitory effects on protein tyrosine phosphatase 1B (PTP1B) of both naturally isolated and synthetically obtained compounds were evaluated. Compounds 4, 9, 13, and 16b exhibited potent PTP1B inhibitory activity, with IC₅₀ values ranging from 0.9 ± 0.2 to 3.9 ± 0.7 μM. The enantiomers (+)-4 and (-)-16b showed enhanced activity compared to their respective enantiomers. Kinetic studies indicate that all active compounds inhibit PTP1B through mixed mechanisms, and molecular docking simulations agree with the experimental assays on PTP1B. Our results suggest that chalcone-meroterpene adducts from the buds of C. operculatus exhibit potential as antidiabetic agents, partly due to their PTP1B enzyme inhibition.

Unlike most common pentacyclic plant triterpenes, glutinol has a methyl group at position C-9 and a Δ₅ double bond. At the same time, it lacks a methyl at C-10. These features significantly modify its chemical behavior compared to other triterpenes, particularly under oxidative conditions. Although the isolation of glutinol from various plant species has been documented, its chemistry remains largely unexplored. In this study, glutinol was isolated from the bark of Balfourodendron riedelianum as a starting material for top-down strategies of structural diversification, which included ring fusion, oxidation, aromatization, and ring cleavage reactions. Glutinol, together with a library of 22 derivatives, was evaluated for antifungal activity against three phytopathogenic Fusarium strains, F. solani, F. graminearum, and F. tucumaniae. Some of the derivatives displayed antifungal activity; in particular, compound 12, featuring a triazine ring, displayed the best fungicidal properties against F. solani and F. graminearum, while the ring B cleavage product 23 showed the best activity against F. tucumaniae. This study highlights the potential of glutinol as a scaffold for structural diversification, and these results may contribute to the design of novel fungicidal agents against phytopathogenic strains.

Eighteen nitrogen-containing compounds (1-18) were isolated from cultures of the lichen-associated Streptomyces flavidovirens collected from the Qinghai-Tibet Plateau, including seven phenazine derivatives with three new ones, named subphenazines A-C (2-4), two new furan pyrrolidones (8-9), and nine known alkaloids. The structures were elucidated by spectroscopic data analysis, and absolute configurations were determined by single-crystal X-ray diffraction and ECD calculations. The phenazine-type derivatives, in particular compound 3, exhibited significantly better antineuroinflammatory activity than other isolated compounds (8-18). Compound 3 inhibited the release of proinflammatory cytokines including IL-6, TNF-α, and PGE₂, and the nuclear translocation of NF-κB; it also reduced the oxidative stress and activated the Nrf2 signaling pathway in LPS-induced BV2 microglia cells. In vivo anti-inflammatory activity in zebrafish indicated that 3 inhibited LPS-stimulated ROS generation. These findings suggested that compound 3 might be a potent antineuroinflammatory agent through the regulation of the NF-κB/Nrf2 signaling pathways.

A new polyketide, cladoic acid, was isolated from a fungus of the genus Cladosporium. The structure of the highly oxygenated trans-decalin ring with an all-E triene side chain was elucidated by extensive spectroscopic analysis. The unique chair/twist-boat conformation of the trans-decalin core and the flexibility of the B-ring were demonstrated by computer-aided conformational analysis. Cladoic acid was active against Trypanosoma cruzi and inhibited the proliferation of amastigotes and epimastigotes with IC₅₀ values of 27 and 46 μM, respectively, but it did not show any appreciable activity against P388 murine leukemia cells, bacteria, or fungi, indicating it is a potential candidate for drug development against Chagas disease.