Aminotenuazonic Acid: Isolation, Structure Elucidation, Total Synthesis and Herbicidal Activity of a New Tetramic Acid from Fruiting Bodies of Laccaria Species

• Published in: Chemistry : a European journal Vol. 25; no. 44; pp. 10333 - 10341
• Main Authors: Schrey, Hedda, Backenköhler, Jana, Kogler, Herbert, Plaumann, Markus, Spiteller, Peter
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 06.08.2019; Wiley Subscription Services, Inc
• Subjects: 3-acyltetramic acids; Acids; Chemistry; Chemistry, Multidisciplinary; Fruit bodies; fungi; Isoleucine; Mushrooms; Mycotoxins; Natural products; NMR; Nuclear magnetic resonance; Physical Sciences; phytotoxicity; Pine trees; Science & Technology; Tenuazonic acid; total synthesis; Two dimensional analysis; METABOLITES; CHEMICAL-SHIFTS; IDENTIFICATION; MICROORGANISMS; natural products; phytotoxicity; 3-acyltetramic acids; fungi; BIOSYNTHESIS; BIOCHEMISTRY; ALTERNARIA-TENUIS AUCT; total synthesis; TENUAZONIC ACID; DERIVATIVES; BICOLOR; phytotoxic activity
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201901405

(5S,6S)‐Aminotenuazonic acid, a new 3‐acyltetramic acid, related to the well‐known mycotoxin tenuazonic acid has been isolated from fruiting bodies of Laccaria bicolor. Its structure was mostly established by analysis of its 2D NMR and HR‐(+)‐ESI‐MS spectra. A total synthesis starting from N‐Boc‐l‐isoleucine gave (5S,6S)‐aminotenuazonic acid in 8 % yield over nine steps (67 % de). The key steps of the total synthesis are a light‐initiated Hofmann–Löffler–Freytag radical chain reaction and a Dieckmann cyclisation. The relative and absolute configurations of the natural product were determined by comparison of its NMR and CD spectra with those of the corresponding enantiopure synthetic compounds. Metabolic profiling of crude extracts of different mushrooms showed that aminotenuazonic acid is present in all four of the investigated Laccaria species. Aminotenuazonic acid shows phytotoxic activities against the root and shoot growth of Lepidium sativum, Pinus sylvestris and Arabidopsis thaliana comparable to those of tenuazonic acid. Unravelling some fungi secrets: (5S,6S)‐Aminotenuazonic acid, a new 3‐acyltetramic acid, which is structurally closely related to the well‐known mycotoxin (5S,6S)‐tenuazonic acid was found in fruiting bodies of several Laccaria species, namely, in L. bicolor. The new alkaloid exhibits herbicidal and cytotoxic activities comparable to those of tenuazonic acid.