Integrative Biology Journals

Natural Products and Bioprospecting ›› 2026, Vol. 16 ›› Issue (2): 28-28.DOI: 10.1007/s13659-025-00579-8

• ORIGINAL ARTICLES • Previous Articles     Next Articles

Polydosetins & pullularins—bioactive tetramic acids & cyclodepsipeptides from the endophytic and nematophagous fungus Polydomus karssenii

Natalia A. Llanos-López1,2, Jan-Peer Wennrich1,2,5, Janette Miled1,2, Samad Ashrafi3,4, Wolfgang Maier3, Frank Surup1,2, Marc Stadler1,2   

  1. 1. Department of Microbial Drugs, Helmholtz Centre for Infection Research (HZI) and German Centre for Infection Research (DZIF), DZIF Partner Site Hannover-Brunswick, Germany, Inhoffenstrasse 7, 38124 Brunswick, Germany;
    2. Institute of Microbiology, Technische Universität Braunschweig, Spielmannstraße 7, 38106 Brunswick, Germany;
    3. Institute for Epidemiology and Pathogen Diagnostics, Julius Kühn Institute (JKI)-Federal Research Centre for Cultivated Plants, Messeweg 11-12, 38104 Brunswick, Germany;
    4. Department of Zoology and Entomology, University of the Free State, Bloemfontein 9300, South Africa;
    5. Laboratory of Fungal Genetics and Metabolism, Institute of Microbiology of the Czech Academy of Sciences, Prague 14220, Czechia
  • Received:2025-10-02 Online:2026-04-22 Published:2026-04-22
  • Contact: Marc Stadler,Email:marc.stadler@helmholtz-hzi.de
  • Supported by:
    The authors want to thank Wera Collisi for conducting the cytotoxicity and antimicrobial assays, Kirsten Harmrolfs and Esther Surges for performing the NMR spectroscopic measurements, and Aileen Gollasch for recording HRESIMS data. NAL is grateful for a PhD stipend grant (program ID 57552340) from the German Academic Exchange Service (DAAD). We express our sincere gratitude to the late Soleiman Helaly and the Alexander von Humboldt Foundation, supporting him with a scholarship. This work was supported by funds of the Landwirtschaftliche Rentenbank, Germany. C. elegans strain N2 was provided by the Caenorhabditis Genetics Center (CGC), which is funded by the National Institute of Health (NIH) Office of Research Infrastructure Programs (P40 OD010440). Funding from the European Union’s Horizon 2020 research and innovation program (RISE) under the Marie Skłodowska-Curie grant agreement No. 101008129, project acronym “Mycobiomics” to MS and J-P W is also gratefully acknowledged.

Polydosetins & pullularins—bioactive tetramic acids & cyclodepsipeptides from the endophytic and nematophagous fungus Polydomus karssenii

Natalia A. Llanos-López1,2, Jan-Peer Wennrich1,2,5, Janette Miled1,2, Samad Ashrafi3,4, Wolfgang Maier3, Frank Surup1,2, Marc Stadler1,2   

  1. 1. Department of Microbial Drugs, Helmholtz Centre for Infection Research (HZI) and German Centre for Infection Research (DZIF), DZIF Partner Site Hannover-Brunswick, Germany, Inhoffenstrasse 7, 38124 Brunswick, Germany;
    2. Institute of Microbiology, Technische Universität Braunschweig, Spielmannstraße 7, 38106 Brunswick, Germany;
    3. Institute for Epidemiology and Pathogen Diagnostics, Julius Kühn Institute (JKI)-Federal Research Centre for Cultivated Plants, Messeweg 11-12, 38104 Brunswick, Germany;
    4. Department of Zoology and Entomology, University of the Free State, Bloemfontein 9300, South Africa;
    5. Laboratory of Fungal Genetics and Metabolism, Institute of Microbiology of the Czech Academy of Sciences, Prague 14220, Czechia
  • 通讯作者: Marc Stadler,Email:marc.stadler@helmholtz-hzi.de
  • 基金资助:
    The authors want to thank Wera Collisi for conducting the cytotoxicity and antimicrobial assays, Kirsten Harmrolfs and Esther Surges for performing the NMR spectroscopic measurements, and Aileen Gollasch for recording HRESIMS data. NAL is grateful for a PhD stipend grant (program ID 57552340) from the German Academic Exchange Service (DAAD). We express our sincere gratitude to the late Soleiman Helaly and the Alexander von Humboldt Foundation, supporting him with a scholarship. This work was supported by funds of the Landwirtschaftliche Rentenbank, Germany. C. elegans strain N2 was provided by the Caenorhabditis Genetics Center (CGC), which is funded by the National Institute of Health (NIH) Office of Research Infrastructure Programs (P40 OD010440). Funding from the European Union’s Horizon 2020 research and innovation program (RISE) under the Marie Skłodowska-Curie grant agreement No. 101008129, project acronym “Mycobiomics” to MS and J-P W is also gratefully acknowledged.

Abstract: In course of investigating the endophytic and nematode-associated fungus Polydomus karssenii for the production of secondary metabolites, seven previously undescribed natural products were isolated from liquid and solid-state fermentations. 1D and 2D NMR spectroscopy, together with HR-ESI-MS data, enabled the elucidation of the planar structures of 3-decalinoyltetramic acids polydosetins A-E (1-5) and cyclodepsipeptides pullularins G and H (6 and 7). The relative configurations of the decalin moiety of 1-5 were determined based on ROESY correlations and 1H-1H coupling constants. The configuration of the side chains was established through a detailed J-resolved analysis (Murata's method) in combination with chemical shift comparison to model compounds. Absolute stereochemistry of 1-5 was assigned based on ECD data, and confirmed by Mosher's method utilizing 3. Finally, the absolute configuration of amino acid residues in 6 and 7 was determined through advanced Marfey's method. Bioassays revealed that compounds 1, 3, 5, and 7 were active against Gram-positive bacteria, 3 and 5 exhibited antifungal activity, and 1 and 2 showed nematicidal effects. These results underscore the untapped chemical potential of P. karssenii and highlight the importance of exploring nematode-associated fungi as sources of new natural products with potential antimicrobial and nematicidal properties.

Key words: Polydomus, Tetramic acids, Cyclodepsipeptides, Antimicrobial, Nematicidal

摘要: In course of investigating the endophytic and nematode-associated fungus Polydomus karssenii for the production of secondary metabolites, seven previously undescribed natural products were isolated from liquid and solid-state fermentations. 1D and 2D NMR spectroscopy, together with HR-ESI-MS data, enabled the elucidation of the planar structures of 3-decalinoyltetramic acids polydosetins A-E (1-5) and cyclodepsipeptides pullularins G and H (6 and 7). The relative configurations of the decalin moiety of 1-5 were determined based on ROESY correlations and 1H-1H coupling constants. The configuration of the side chains was established through a detailed J-resolved analysis (Murata's method) in combination with chemical shift comparison to model compounds. Absolute stereochemistry of 1-5 was assigned based on ECD data, and confirmed by Mosher's method utilizing 3. Finally, the absolute configuration of amino acid residues in 6 and 7 was determined through advanced Marfey's method. Bioassays revealed that compounds 1, 3, 5, and 7 were active against Gram-positive bacteria, 3 and 5 exhibited antifungal activity, and 1 and 2 showed nematicidal effects. These results underscore the untapped chemical potential of P. karssenii and highlight the importance of exploring nematode-associated fungi as sources of new natural products with potential antimicrobial and nematicidal properties.

关键词: Polydomus, Tetramic acids, Cyclodepsipeptides, Antimicrobial, Nematicidal