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Publikationen - Natur- und Wirkstoffchemie

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Publikation

Ditfe, T.; Bette, E.; N. Sultani, H.; Otto, A.; Wessjohann, L. A.; Arnold, N.; Westermann, B.; Synthesis and biological evaluation of highly potent fungicidal deoxy‐hygrophorones Eur. J. Org. Chem. 2021, 3827-3836, (2021) DOI: 10.1002/ejoc.202100729

Although stripped from hydroxyl-groups, deoxygenated hygrophorones remain highly active against severe phytopathogens. The synthesis to these natural product congeners is achieved in rearrangement sequences, with an optimized deprotection strategy avoiding retro-aldol reactions. The activities are comparable to fungicides used in agriculture. Based on naturally occurring hygrophorones, racemic di- and mono-hydroxylated cyclopentenones bearing an aliphatic side chain have been produced in short synthetic sequences starting from furfuryl aldehyde. For the series of dihydroxylated trans-configured derivatives, an Achmatowicz-rearrangement and a Caddick-ring contraction were employed, and for the series of trans-configured mono-hydroxylated derivatives a Piancatelli-rearrangement. All final products showed good to excellent fungicidal activities against the plant pathogens B. cinerea, S. tritici and P. infestans.
Publikation

Otto, A.; Porzel, A.; Westermann, B.; Brandt, W.; Wessjohann, L.; Arnold, N.; Structural and stereochemical elucidation of new hygrophorones from Hygrophorus abieticola (Basidiomycetes) Tetrahedron 73, 1682-1690, (2017) DOI: 10.1016/j.tet.2017.02.013

Four new hygrophorones (1–4) together with the known hygrophorone B12 (5) have been isolated from fruiting bodies of the basidiomycete Hygrophorus abieticola Krieglst. ex Gröger & Bresinsky. Their structures were assigned on the basis of extensive one and two dimensional NMR spectroscopic analyses as well as ESI-HRMS measurements. Among these compounds, two previously undescribed hygrophorone types, named hygrophorone H12 (3) and 2,3-dihydrohygrophorone H12 (4), were identified. The absolute configuration of hygrophorone E12 (2) is suggested based on quantum chemical CD calculations, while a semisynthetic approach in conjunction with computational studies and analysis of NOE interactions allowed the stereochemical assignment of compounds 3 and 4. Additionally, semisynthetic derivatives of hygrophorone B12 (5) were generated by acetylation of the hydroxyl groups. The biological activity of the natural and semisynthetic hygrophorones was evaluated against phytopathogenic organisms, revealing that the α,β-unsaturated carbonyl functionality is likely to be an essential structural feature. Hygrophorone B12 (5) was identified as the most active compound, acting against both ascomycetous fungi and oomycetes.
Publikation

Otto, A.; Laub, A.; Haid, M.; Porzel, A.; Schmidt, J.; Wessjohann, L.; Arnold, N.; Tulasporins A–D, 19-Residue Peptaibols from the Mycoparasitic Fungus Sepedonium tulasneanum Nat. Prod. Commun. 11, 1821-1824, (2016) DOI: 10.1177/1934578X1601101212

Four new 19-residue peptaibols, named tulasporins A–D (1–4), were isolated from the semi-solid cultures of Sepedonium tulasneanum. Their structures were elucidated on the basis of extensive ESI-HRMSn fragmentation studies as well as 1H NMR spectroscopic analyses. Interestingly, the structures of tulasporins A–D (1–4) resemble those of chrysospermins isolated earlier from cultures of S. chrysospermum. Previously, it was hypothesized that the peptaibol production by Sepedonium species correlates with the morphology of the aleurioconidia, as exclusively round-shaped aleurioconidia forming species produced peptaibols. Since the investigated Sepedonium tulasneanum produces oval aleurioconidia, this study can be considered as the first report of peptaibols from a Sepedonium strain with oval-shaped aleurioconidia. Thus, it could be demonstrated that both round as well as oval aleurioconidia forming Sepedonium species are able to produce peptaibols. Tulasporins A-D (1–4), when tested against phytopathogenic fungi, exhibited good growth inhibitory activity against both Botrytis cinerea and Phytophthora infestans, while they were devoid of significant activity against Septoria tritici.
Publikation

Otto, A.; Porzel, A.; Schmidt, J.; Brandt, W.; Wessjohann, L.; Arnold, N.; Structure and Absolute Configuration of Pseudohygrophorones A12 and B12, Alkyl Cyclohexenone Derivatives from Hygrophorus abieticola (Basidiomycetes) J. Nat. Prod. 79, 74-80, (2016) DOI: 10.1021/acs.jnatprod.5b00675

Pseudohygrophorones A(12) (1) and B(12) (2), the first naturally occurring alkyl cyclohexenones from a fungal source, and the recently reported hygrophorone B(12) (3) have been isolated from fruiting bodies of the basidiomycete Hygrophorus abieticola Krieglst. ex Gröger & Bresinsky. Their structures were assigned on the basis of extensive one- and two-dimensional NMR spectroscopic analysis as well as ESI-HRMS measurements. The absolute configuration of the three stereogenic centers in the diastereomeric compounds 1 and 2 was established with the aid of (3)JH,H and (4)JH,H coupling constants, NOE interactions, and conformational analysis in conjunction with quantum chemical CD calculations. It was concluded that pseudohygrophorone A(12) (1) is 4S,5S,6S configured, while pseudohygrophorone B(12) (2) was identified as the C-6 epimer of 1, corresponding to the absolute configuration 4S,5S,6R. In addition, the mass spectrometric fragmentation behavior of 1-3 obtained by the higher energy collisional dissociation method allows a clear distinction between the pseudohygrophorones (1 and 2) and hygrophorone B(12) (3). The isolated compounds 1-3 exhibited pronounced activity against phytopathogenic organisms.
Publikation

Otto, A.; Laub, A.; Wendt, L.; Porzel, A.; Schmidt, J.; Palfner, G.; Becerra, J.; Krüger, D.; Stadler, M.; Wessjohann, L.; Westermann, B.; Arnold, N.; Chilenopeptins A and B, Peptaibols from the Chilean Sepedonium aff. chalcipori KSH 883 J. Nat. Prod. 79, 929-938, (2016) DOI: 10.1021/acs.jnatprod.5b01018

The Chilean Sepedonium aff. chalcipori strain KSH 883, isolated from the endemic Boletus loyo Philippi, was studied in a polythetic approach based on chemical, molecular, and biological data. A taxonomic study of the strain using molecular data of the ITS, EF1-α, and RPB2 barcoding genes confirmed the position of the isolated strain within the S. chalcipori clade, but also suggested the separation of this clade into three different species. Two new linear 15-residue peptaibols, named chilenopeptins A (1) and B (2), together with the known peptaibols tylopeptins A (3) and B (4) were isolated from the semisolid culture of strain KSH 883. The structures of 1 and 2 were elucidated on the basis of HRESIMS(n) experiments in conjunction with comprehensive 1D and 2D NMR analysis. Thus, the sequence of chilenopeptin A (1) was identified as Ac-Aib(1)-Ser(2)-Trp(3)-Aib(4)-Pro(5)-Leu(6)-Aib(7)-Aib(8)-Gln(9)-Aib(10)-Aib(11)-Gln(12)-Aib(13)-Leu(14)-Pheol(15), while chilenopeptin B (2) differs from 1 by the replacement of Trp(3) by Phe(3). Additionally, the total synthesis of 1 and 2 was accomplished by a solid-phase approach, confirming the absolute configuration of all chiral amino acids as l. Both the chilenopeptins (1 and 2) and tylopeptins (3 and 4) were evaluated for their potential to inhibit the growth of phytopathogenic organisms.
Publikation

Bette, E.; Otto, A.; Dräger, T.; Merzweiler, K.; Arnold, N.; Wessjohann, L.; Westermann, B.; Isolation and Asymmetric Total Synthesis of Fungal Secondary Metabolite Hygrophorone B12 Eur. J. Org. Chem. 2015, 2357-2365, (2015) DOI: 10.1002/ejoc.201403455

Hygrophorone B12, a new antifungal constituent from the fruiting bodies of Hygrophorus abieticola, has been isolated and subsquently synthesized in enantiomerically pure form. The total synthesis includes a Sharpless asymmetric dihydroxylation protocol as the stereodifferentiating step, followed by two diastereoselective aldol‐type reactions. The approach allows the unambiguous control of all three stereogenic centres, and, furthermore, unequivocal determination of the relative and absolute configuration of antibiotic hygrophorones B for the first time.
Publikation

Otto, A.; Laub, A.; Porzel, A.; Schmidt, J.; Wessjohann, L.; Westermann, B.; Arnold, N.; Isolation and Total Synthesis of Albu­peptins A-D: 11-Residue Peptaibols from the Fungus Gliocladium album Eur. J. Org. Chem. 2015, 7449-7459, (2015) DOI: 10.1002/ejoc.201501124

Four new 11‐mer peptaibols, named albupeptins A–D (1–4), were isolated from cultures of the fungus Gliocladium album. Their structures were elucidated on the basis of 1D and 2D NMR spectroscopy, as well as ESI‐HRMSn analysis. The sequence of albupeptin A (1) was thus identified as Ac‐Aib1‐Aib2‐Val3‐Leu4‐Aib5‐Pro6‐Iva7‐Leu8‐Gln9‐Aib10‐Leuol11. Albupeptins B (2) and C (3) feature an exchange of Aib5 by Iva5 and of Aib1 by Iva1, respectively, and albupeptin D (4) contains both Iva1 and Iva5 residues. The stereochemistry of the isolated peptaibols 1–4 was unambiguously assigned by 1H NMR chemical shift analysis in conjunction with solid‐phase peptide synthesis. By using this approach, the absolute configuration of the Iva residues in albupeptins A (1) and C (3) was determined to be D, whereas albupeptins B (2) and D (4) feature an additional Iva5 residue with an L configuration. Thus, albupeptins B (2) and D (4) belong to the rare class of peptaibols that have both stereoisomers of Iva in the same sequence.
Publikation

Otto, A.; Porzel, A.; Schmidt, J.; Wessjohann, L.; Arnold, N.; A study on the biosynthesis of hygrophorone B12 in the mushroom Hygrophorus abieticola reveals an unexpected labelling pattern in the cyclopentenone moiety Phytochemistry 118, 174-180, (2015) DOI: 10.1016/j.phytochem.2015.08.018

The hitherto unknown natural formation of hygrophorones, antibacterial and antifungal cyclopentenone derivatives from mushrooms, was investigated for hygrophorone B12 in Hygrophorus abieticola Krieglst. ex Gröger & Bresinsky by feeding experiments in the field using 13C labelled samples of d-glucose and sodium acetate. The incorporation of 13C isotopes was extensively studied using 1D and 2D NMR spectroscopy as well as ESI-HRMS analyses. In the experiment with [U-13C6]-glucose, six different 13C2 labelled isotopomers were observed in the 2D INADEQUATE spectrum due to incorporation of [1,2-13C2]-acetyl-CoA. This labelling pattern demonstrated that hygrophorone B12 is derived from a fatty acid-polyketide route instead of a 1,4-α-d-glucan derived anhydrofructose pathway. The experiment with [2-13C]-acetate revealed an unexpected incorporation pattern in the cyclopentenone functionality of hygrophorone B12. Four single-labelled isotopomers, in particular [1-13C]-, [2-13C]-, [3-13C]-, and [4-13C]-hygrophorone B12, were detected that showed only half enrichment in comparison to the respective labelled alkyl side chain carbons. This labelling pattern indicates the formation of a symmetrical intermediate during hygrophorone B12 biosynthesis. Based on these observations, a biogenetic route via a 4-oxo fatty acid and a chrysotrione B homologue is discussed.
Publikation

Otto, A.; Porzel, A.; Schmidt, J.; Wessjohann, L.; Arnold, N.; Penarines A–F, (nor-)sesquiterpene carboxylic acids from Hygrophorus penarius (Basidiomycetes) Phytochemistry 108, 229-233, (2014) DOI: 10.1016/j.phytochem.2014.09.005

Five sesquiterpene carboxylic acids (1–5) and one nor-sesquiterpene carboxylic acid (6) of the very rare ventricosane type, named penarines A–F, were isolated from fruiting bodies of the basidiomycete Hygrophorus penarius (Hygrophoraceae). This is the first report of (nor)-sesquiterpenes isolated from basidiocarps of the family Hygrophoraceae. Their structures were elucidated on the basis of extensive 1D (1H, 13C) and 2D (HSQC, HMBC, COSY, ROESY) NMR spectroscopic analyses as well as high-resolution mass spectrometry studies. Additionally, the only known member of this rare type of sesquiterpenes, ventricos-7(13)-ene (7), could be identified via headspace GC–MS analysis in a fruiting body of H. penarius. Compounds 1–6 were devoid of remarkable antifungal activity against Cladosporium cucumerinum. Additionally, the cytotoxic activities of compounds 1 and 2 were evaluated against the human prostate cancer cell line PC-3 and the colon cancer cell line HT-29 showing no significant cytotoxic activity.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
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