Alveolarides: Antifungal Peptides from Microascus alveolaris Active against Phytopathogenic Fungi

Three novel cyclodepsipeptides, alveolarides A (1), B (2), and C (3), each possessing the rare 2,3-dihydroxy-4-methyltetradecanoic acid unit and a β-phenylalanine amino acid residue, along with the known peptide scopularide were isolated and identified from the culture broth of Microascus alveolaris strain PF1466. The pure compounds were evaluated for biological activity, and alveolaride A (1) provided strong in vitro activity against the plant pathogens Pyricularia oryzae, Zymoseptoria tritici, and Ustilago maydis. Moderate activity of alveolaride A was observed under in planta conditions against Z. tritici, Puccinia triticina, and Phakopsora pachyrhizi. Structures of 1, 2, and 3 were determined by detailed analysis of NMR (1D and 2D) and mass spectrometry data. The partial absolute configuration of alveolaride A (1) was established.