New Massarilactones, Massarigenin E, and Coniothyrenol, Isolated from the Endophytic Fungus Coniothyrium sp. from Carpobrotus edulis

Kock, Ines; Krohn, Karsten; Egold, Hans; Draeger, Siegfried; Schulz, Barbara; Rheinheimer, Joachim

doi:10.1002/ejoc.200600987

Cited by 31 publications

(20 citation statements)

References 8 publications

(19 reference statements)

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“…Scirpyrone A (1) is structurally related to cladobotrin I (11) [25] and tetillapyrone (12), [26] a relatively rare class of α-pyrones with the furylpyranone skeleton, but dif-fers significantly in having a γ-lactone ring joined to the pyrone moiety through C-6 and C-7, rather than a C-5-C-7 connected furan or tetrahydrofuran in known compounds, representing the first described 6-(5-oxotetrahydrofuran-2yl)-2H-pyran-2-one. Scirpyranes A (4) and B (5) are new members of the furo[3,4-b]pyran-5-ones, of which only a limited number of natural product examples have been reported, [10,[27][28][29][30][31][32] whereas scirpyranes C (6) and D (7) are the ring-opened products of 4 and its stereoisomer, respectively. Scirpyranes A (4) and B (5) are new members of the furo[3,4-b]pyran-5-ones, of which only a limited number of natural product examples have been reported, [10,[27][28][29][30][31][32] whereas scirpyranes C (6) and D (7) are the ring-opened products of 4 and its stereoisomer, respectively.…”

Section: Discussionmentioning

confidence: 99%

α‐Pyrones and Pyranes from the Plant Pathogenic Fungus Pestalotiopsis scirpina

Li¹,

Wu²,

Ding³

et al. 2012

Eur J Org Chem

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Three new α‐pyrones, scirpyrones A–C (1–3), and four new pyranes, scirpyranes A–D (4–7), were isolated from solid cultures of the plant pathogen Pestalotiopsis scirpina. Their structures were elucidated primarily by NMR experiments. The absolute configurations of C‐7 and C‐2′ in 1, C‐7 in 2, and C‐6 and C‐7 in 3 were deduced on the basis of circular dichroism (CD) data, whereas those of the secondary alcohols in 4–7 were determined by a modification of Mosher's method. Compound 1 is the first described 6‐(5‐oxotetrahydrofuran‐2‐yl)‐2H‐pyran‐2‐one. Compounds 4–6 showed significant cytotoxicity towards MCF‐7 cells.

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Section: Discussionmentioning

confidence: 99%

α‐Pyrones and Pyranes from the Plant Pathogenic Fungus Pestalotiopsis scirpina

Li¹,

Wu²,

Ding³

et al. 2012

Eur J Org Chem

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“…The other known compounds were determined to be massarilactone D (7), 11 enalin A (8), 12 massarilactone G (9), 13 palmarumycin CJ-12,371 (10), 14 palmarumycin CP 2 (11), 15 palmarumycin CP 19 (12), 16 massarigenin C (13), 17 and trichocladinol B (14). 10 The Insect Antifeedant Activities.…”

Section: ■ Introductionmentioning

confidence: 99%

Paraverrucsins A–F, Antifeedant, and Antiphytopathogenic Polyketides from Rhizospheric Paraphaeosphaeria verruculosa and Induced Bioactivity Enhancement by Coculturing with Host Plant Dendrobium officinale

Yang

Wang

et al. 2020

ACS Omega

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Six new polyketides named paraverrucsins A−F (1− 6) with oxabicyclic and dioxatricyclic skeletons, together with eight known metabolites (7−14), were discovered and isolated from the fermentation medium of Paraphaeosphaeria verruculosa. Paraverrucsin A−C possessed a novel decarboxylated skeleton compared with that of trichocladinols. Their structures were elucidated by extensive spectral analysis and DP4+ calculations. Paraverrucsins B/C and D/E were isolated as a mixture for the mutarotation occurred at C-2. Paraverrucsins B/C, D/E, F/ trichocladinol B, 8, and 9 displayed antifeedant activities against silkworm larvae, with antifeedant index percentages ranging from 62.5 to 93.0%, at a concentration of 50 μg/cm 2 . Among them, Paraverrucsins B/C and 9 had EC 50 values at 13.9 and 18.2 μg/cm 2 . Most compounds showed antifungal activities against phytopathogenic fungi with minimum inhibitory concentration (MIC) values of 16−64 μg/mL. Coculture of P. verruculosa and host plant Dendrobium officinale leads to the enhancement of antifeedant and antiphytopathogenic activities. Compounds 1, 2/3, 4/5, 6/14 were tested for cytotoxicity against five human carcinoma cell lines, HL-60, A549, MCF-7, SW480, and SMMC-7721, while they exhibited selected cytotoxicity against SW480 with inhibition ratios of 32−38% at a concentration of 40 μM.

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“…Krohn and co-workers later discovered massarilactones C and D from the endophytic fungus Coniothyrium sp, but despite the crude extract of all six isolates showing antifungal, antibacterial and antialgal activities, the purified substances were inactive against the gram-positive bacterium Bacillus megaterium, the fungus Microbotryum violaceum, and the green alga Chlorella fusca. 20 Further work by the same group uncovered massarilactones E, F and G and the acetonide 16, also isolated from Coniothyrium sp. 21 Massarilactone H was later isolated from the marine fungus Phoma herbarum.…”

Section: Massarilactonesmentioning

confidence: 98%

“…Several groups have been involved in the isolation, structure elucidation, and synthesis of the furo [3,4-b]pyran-based natural products. The furo [3,4-b]pyran scaffold is found in only a handful of known natural products, including TAN-2483A and B, 16 the fusidilactones, 17,18 the massarilactones, [19][20][21][22] and waol A 23,24 and B. 25 The biological activity of these natural products is broad, and includes cytotoxic, antibacterial, antifungal and antialgal properties.…”

Section: Introductionmentioning

confidence: 99%

Toward the Synthesis of (–)-TAN-2483B Lactam Analogues

Stirrat¹

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Natural products continue to be an abundant source of lead compounds for drug discovery and development. (–)-TAN-2483A and (–)-TAN-2483B, isolated from the culture of a filamentous fungus, incorporate an unusual furo[3,4-b]pyran-5-one scaffold. TAN-2483A was initially reported to inhibit the c-Src tyrosine kinase enzyme, a potential anticancer target, and parathyroid hormone-induced bone resorption. TAN-2483B, on the other hand, was not isolated in sufficient quantities for biological testing. The synthesis of TAN-2483B is therefore desirable from a drug discovery perspective. Several analogues of TAN-2483B that are functionalised at the propenyl sidechain have previously been synthesised in the Harvey group and have shown promising biological activity. For example, the (Z)-ethyl ester analogue showed micromolar inhibition of HL-60 cells and Bruton’s tyrosine kinase, a protein involved in B-cell maturation that is implicated in certain cancers. The lactone moiety of TAN-2483B and its sidechain analogues, however, appears to be unstable to nucleophilic attack. The aim of this thesis was to investigate the viability of a synthetic route toward lactam analogues of TAN-2483B. It was proposed that substituting the lactone for a lactam would increase the stability of the compound in nucleophilic media. Moreover, the lactam nitrogen may provide a site for further functionalisation of the compound for future structure-activity relationship studies. Because installation of the (Z)-ethyl ester sidechain via Wittig conditions has previously been found to be more facile than installation of the (E)-propenyl sidechain found in the natural product, investigations into forming the lactam ring system were carried out on the ethyl ester advanced intermediates. Reductive amination of a ketone intermediate was envisaged to install the amine prior to a palladium-catalysed carbonylation/lactam formation step. The promising bioactivity of the (Z)-ethyl ester analogue was anticipated to be retained in the target lactam analogues. It was found that the substrates of the proposed reductive amination, the advanced ketone intermediates, were incompatible with the tested conditions, presumably due to base sensitivity. Three by-products from the reductive amination experiments were isolated and tentatively characterised by NMR spectroscopy and HRMS. An alternative route toward lactam analogues of TAN-2483B, via intermediate amines accessed by the substitution of an activated alcohol, was briefly investigated with encouraging results. Further optimisation of the synthetic route toward analogues of TAN-2483B was also achieved. Removal of a purification step enabled the more expedient two-step synthesis of a diol intermediate. The two-step transformation to (Z)- and (E)-ethyl ester intermediates, via sodium periodate-mediated diol cleavage and Wittig olefination, proceeded in the highest yield obtained to date. Investigations into the desilylation of a trimethylsilyl-protected acetylene were also conducted. Although lactam analogues of TAN-2483B were not obtained in this study, progress was made toward their synthesis. The alternative route toward amines that was briefly explored here appears promising, and work is ongoing in the Harvey group to access lactam (and other) analogues of TAN-2483B, in addition to the natural product itself.

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New Massarilactones, Massarigenin E, and Coniothyrenol, Isolated from the Endophytic Fungus Coniothyrium sp. from Carpobrotus edulis

Cited by 31 publications

References 8 publications

α‐Pyrones and Pyranes from the Plant Pathogenic Fungus Pestalotiopsis scirpina

α‐Pyrones and Pyranes from the Plant Pathogenic Fungus Pestalotiopsis scirpina

Paraverrucsins A–F, Antifeedant, and Antiphytopathogenic Polyketides from Rhizospheric Paraphaeosphaeria verruculosa and Induced Bioactivity Enhancement by Coculturing with Host Plant Dendrobium officinale

Toward the Synthesis of (–)-TAN-2483B Lactam Analogues

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