Aromatic polyketides from a caterpillar associated Alternaria sp.

Shen, Ye; Xu, Qin; Cheng, Ping; Liu, Cheng-Li; Lu, Zhi Yao; Li, Wei; Wang, Ting Ting; Lu, Yan; Tan, Ren Xiang; Ge, Hui; Jiao, Rui Hua

doi:10.1016/j.tetlet.2017.06.071

Cited by 12 publications

(6 citation statements)

References 11 publications

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“…After subsequent isolation and purification we were able to confirm the identity of calyxanthone (12, m/z 287.1) and identified the other compounds as alternaphenol B (11, m/z 271.9), 16 penicixanthone D (13 m/z 295.5), 17 and an as yet unknown xanthone (m/z 547.1) (Figures S92−S97).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Subplenones A–J: Dimeric Xanthones with Antibacterial Activity from the Endophytic Fungus Subplenodomus sp. CPCC 401465

Cai,

Hu,

Zhang

et al. 2023

J. Nat. Prod.

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Subplenones A−J (1−10), 10 new xanthone dimers, have been isolated and characterized from the endophytic fungus Subplenodomus sp. CPCC 401465, which resides within the Chinese medicinal plant Gentiana straminea. The isolation process was guided by antibacterial assays and molecular-networking-based analyses. The chemical structures of these compounds were elucidated through the interpretation of nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectrometry (HRESIMS) data. Furthermore, the relative configuration of the compounds was determined using NMR and single-crystal X-ray diffraction analyses, and the absolute configuration was established using electronic circular dichroism calculations. All of the isolated compounds exhibited significant inhibitory activity against Gram-positive bacteria. Notably, compounds 1, 5, and 7 displayed remarkable inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA) ATCC 700698, with a minimum inhibitory concentration (MIC) of 0.25 μg/mL, and against vancomycin-resistant Enterococcus faecium (VRE) ATCC 700221, with MIC values ranging from 0.5 to 1.0 μg/mL.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Subplenones A–J: Dimeric Xanthones with Antibacterial Activity from the Endophytic Fungus Subplenodomus sp. CPCC 401465

Cai,

Hu,

Zhang

et al. 2023

J. Nat. Prod.

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“…A bibliographic survey confirmed the considerable difficulties in distinguishing these two scaffolds, as such pairs of compounds display identical carbon connectivities, and thus similar sets of HMBC correlations [ 9 ]. Interestingly, oxepinedione-containing metabolites were claimed to have been isolated from fungal sources on several occasions, mostly from micromycetes [ 10 , 11 , 12 ]. It turned out that many such metabolites had been erroneously elucidated at first and had later been revised into carboxylic acid-containing xanthones [ 9 , 13 ].…”

Section: Resultsmentioning

confidence: 99%

Ominoxanthone—The First Xanthone Linearly Fused to a γ-Lactone from Cortinarius ominosus Bidaud Basidiomata. CASE- and DFT-Based Structure Elucidation

et al. 2023

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The UHPLC–HRMS analysis of Cortinarius ominosus basidiomata extract revealed that this mushroom accumulated elevated yields of an unreported specialized metabolite. The molecular formula of this unknown compound, C17H10O8, indicated that a challenging structure elucidation lay ahead, owing to its critically low H/C atom ratio. The structure of this new isolate, namely ominoxanthone (1), could not be solved from the interpretation of the usual set of 1D/2D NMR data that conveyed too limited information to afford a single, unambiguous structure. To remedy this, a Computer-Assisted Structure Elucidation (CASE) workflow was used to rank the different possible structure candidates consistent with our scarce spectroscopic data. DFT-based chemical shift calculations on a limited set of top-ranked structures further ascertained the determined structure for ominoxanthone. Although the determined scaffold of ominoxanthone is unprecedented as a natural product, a plausible biosynthetic scenario involving a precursor known from cortinariaceous sources and classical biogenetic reactions could be proposed.

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“…The structures of some other natural products, such as wentiquinones A and B ( 12 and 13 ), CT-1 ( 14 ), and compounds 15 − 18 , which were initially assigned the structures as seco -anthraquinones [14,15,16,17,18], are likely incorrectly assigned and their structures should be reassessed. Compounds 19 and 20 [19,20], which were considered being seco -anthraquinones, are also required to be re-checked carefully.…”

Section: Resultsmentioning

confidence: 99%

Structural Revision of Wentiquinone C and Related Congeners from Anthraquinones to Xanthones Using Chemical Derivatization and NMR Analysis

Li¹,

Wang²

2018

Marine Drugs

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Wentiquinone C, which was previously isolated from the marine brown alga-derived endophytic fungus Aspergillus wentii EN-48, was found to be a potent antioxidant against α,α-diphenyl-picrylhydrazyl (DPPH) radical. The structure of wentiquinone C was originally assigned as an anthraquinone derivative (1,10-dihydroxy-3-(hydroxymethyl)-8-methoxydibenzo [b,e]oxepine-6,11-dione, 1) by 1D and 2D NMR experiments. However, the minor differences of the chemical shifts between xanthones and anthraquinones were queried, leading to the structure of 1 to be revised as a xanthone analog (8-hydroxy-6-(hydroxymethyl)-3-methoxy-9-oxo-9H-xanthene-1-carboxylic acid, 2) on the basis of a methylation and subsequent NMR measurements, and was confirmed by X-ray crystallographic analysis. The method established in this paper could be applied to the structural re-examination or revision for some of the reported seco-anthraquinone derivatives.

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Aromatic polyketides from a caterpillar associated Alternaria sp.

Cited by 12 publications

References 11 publications

Subplenones A–J: Dimeric Xanthones with Antibacterial Activity from the Endophytic Fungus Subplenodomus sp. CPCC 401465

Subplenones A–J: Dimeric Xanthones with Antibacterial Activity from the Endophytic Fungus Subplenodomus sp. CPCC 401465

Ominoxanthone—The First Xanthone Linearly Fused to a γ-Lactone from Cortinarius ominosus Bidaud Basidiomata. CASE- and DFT-Based Structure Elucidation

Structural Revision of Wentiquinone C and Related Congeners from Anthraquinones to Xanthones Using Chemical Derivatization and NMR Analysis

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