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A new bicyclic polyketide, amesilide (), along with the previously reported metabolites, chamisides A (), B (), and E (), chaetoconvosins B () and C (), and chaetochromins A () and B (), were isolated from the marine fungus MUT6601. The structures of the compounds were determined by extensive spectrometric (HRMS) and spectroscopic (1D and 2D NMR) analyses, as well as specific rotation. Absolute configurations of the stereogenic centers of amesilide () were determined by a comparison of its experimental circular dichroism (CD) spectrum with its time-dependent density functional theory (TD-DFT) electronic circular dichroism (ECD) spectra. Among them, chaetochromins A () and B () showed strong antibacterial activity against S25 (MBC values of 12.50 µM and MIC values of 6.25 µM) and a moderate cytotoxicity against monocytes (THP-1) and peripheral blood cells (PBMC) (IC values of 33.65-40.01 µM).
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http://dx.doi.org/10.3390/molecules30153169 | DOI Listing |
Molecules
July 2025
Marine Natural Products Team, Institut de Chimie de Nice, Université Côte d'Azur, CNRS UMR 7272, 06108 Nice, France.
A new bicyclic polyketide, amesilide (), along with the previously reported metabolites, chamisides A (), B (), and E (), chaetoconvosins B () and C (), and chaetochromins A () and B (), were isolated from the marine fungus MUT6601. The structures of the compounds were determined by extensive spectrometric (HRMS) and spectroscopic (1D and 2D NMR) analyses, as well as specific rotation. Absolute configurations of the stereogenic centers of amesilide () were determined by a comparison of its experimental circular dichroism (CD) spectrum with its time-dependent density functional theory (TD-DFT) electronic circular dichroism (ECD) spectra.
View Article and Find Full Text PDFJ Org Chem
June 2025
Graduate School of Bioagricultural Sciences, Nagoya UniversityFuro-cho, Chikusa, Nagoya 464-8601, Japan.
Aplysiatoxin (ATX) is a bioactive polyketide natural product produced by cyanobacteria and characterized by macrodiolide and spiroacetal moieties. Many structurally diverse analogs of ATX have been reported but are little studied due to the minuscule quantities in which they have been isolated. We hypothesized that most of these analogs are biosynthesized from anhydroATX, a dehydrated form of ATX, and report a synthesis of the phenolic OMe ether of anhydro-deBr-ATX, as well as syntheses of seven macrodiolide ATX analogs, OTX-B1, B2, M, J, and neo-deBr-ATX-A, G, and J, according to the biosynthetic hypothesis.
View Article and Find Full Text PDFChem Biodivers
July 2025
Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, People's Republic of China.
In the present study, 11 C-polyketides comprising a monocyclic skeleton of an aromatic (1-6 and 11) or a cyclohexanone moiety (7) and an oxygenated bicyclic nucleus (8-10) were isolated from a mutated strain of endophytic fungus Aspergillus terreus RA2905. Five pairs of enantiomers (2a/b-5a/b and 7a/b) were achieved by chiral-phase HPLC separation. The structures of previously unreported asptertides A-H (1-8) were determined by analysis of the spectroscopic data and electronic circular dichroism (ECD) calculations.
View Article and Find Full Text PDFPhytochemistry
June 2025
Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, 100700, China. Electronic address:
The bioassay-guided isolation of an endophytic fungus Talaromyces funiculosus TF37 yielded a total of eleven compounds (1-11), including three undescribed compounds, a bicyclic tetralone named tanicutone D (1) and two prenylated indole alkaloids named mangrovamides L (4) and M (5). The undescribed structures were elucidated by comprehensive spectroscopic analyses of HR-ESI-MS, 1D and 2D NMR, as well as ECD calculations. All isolates were evaluated by the antimicrobial assay against Staphylococcus aureus, Saccharomyces cerevisiae, Candida albicans, and MRSA.
View Article and Find Full Text PDFBiochemistry
January 2025
Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zurich, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland.
Janustatin A is a potently cytotoxic polyketide alkaloid produced at trace amounts by the marine bacterial plant symbiont . Its biosynthetic terminus features an unusual pyridine-containing bicyclic system of unclear origin, in which polyketide and amino acid extension units appear reversed compared to the order of enzymatic modules in the polyketide synthase (PKS)-nonribosomal peptide synthetase (NRPS) assembly line. To elucidate unknown steps in heterocycle formation, we first established robust genome engineering tools in .
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