| Affiliation: | 1. Institut für Organische und Analytische Chemie, Universität Bremen, Leobener Straße 7, 28359 Bremen, Germany;2. Institut für Organische und Analytische Chemie, Universität Bremen, Leobener Straße 7, 28359 Bremen, Germany These authors contributed equally to this work.;3. KIT, Institut für Biologische Grenzflächen 4, Magnetische Resonanz, Postfach 3640, 76021 Karlsruhe, Germany;4. Institut für Biometrie und Medizinische Informatik, Otto von Guericke Universität Magdeburg, Leipziger Straße 44 (Haus 2), 39120 Magdeburg, Germany |
| Abstract: | (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. |
