Euglenatides, potent antiproliferative cyclic peptides isolated from the freshwater photosynthetic microalga Euglena gracilis

A. Ganesan, Mohammed Aldholmi, Rizwan Ahmad, Daniel Carretero-Molina, Ignacio Pérez-Victoria, Jesús Martín, Fernando Reyes, Olga Genilloud, Léa Gourbeyre, Thierry Gefflaut, Hanne Carlsson, Alexei Maklakov, Robert A. Field, Ellis O'Neill, Barrie Wilkinson, Maria O'Connell

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Abstract

By limiting the nitrogen source to glutamic acid, we isolated cyclic peptides from Euglena gracilis containing asparagine and non-proteinogenic amino acids. Structure elucidation was accomplished through spectroscopic methods, mass spectrometry and chemical degradation. The euglenatides potently inhibit pathogenic fungi and cancer cell lines e.g., euglenatide B exhibiting IC 50 values of 4.3 μM in Aspergillus fumigatus and 0.29 μM in MCF-7 breast cancer cells. In an unprecedented convergence of non-ribosomal peptide synthetase and polyketide synthase assembly-line biosynthesis between unicellular species and the metazoan kingdom, euglenatides bear resemblance to nemamides from Caenorhabditis elegans and inhibited both producing organisms E. gracilis and C. elegans. By molecular network analysis, we detected over forty euglenatide-like metabolites in E. gracilis, E. sanguinea and E. mutabilis, suggesting an important biological role for these natural products.

Original languageEnglish
JournalAngewandte Chemie International Edition
Early online date24 Mar 2022
DOIs
Publication statusE-pub ahead of print - 24 Mar 2022

Keywords

  • Antiproliferative
  • Cyclic Peptides
  • Microalgae
  • Natural Products
  • Nematodes

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