Euglenatides, Potent Antiproliferative Cyclic Peptides Isolated from the Freshwater Photosynthetic Microalga <i>Euglena gracilis</i>

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 chemical degradation. The euglenatides potently inhibit pathogenic fungi cancer cell lines e.g., euglenatide B exhibiting IC 50 values of 4.3 μM in Aspergillus fumigatus 0.29 MCF‐7 breast cells. In an unprecedented convergence non‐ribosomal peptide synthetase polyketide synthase assembly‐line biosynthesis between unicellular species metazoan kingdom, bear resemblance nemamides Caenorhabditis elegans inhibited both producing organisms E. C. . molecular network analysis, detected over forty euglenatide‐like metabolites , sanguinea mutabilis suggesting important biological role for these natural products.