New chaetoglobosins from maize infested by Phomopsis leptostromiformis fungi. Production, identification, and semi‐synthesis

Article type: Research Article

Authors: Burlot, Ludovic | Cherton, Jean‐Claude^; | Convert, Odile | Correia, Isabelle | Dennetiere, Bruno

Affiliations: Laboratoire SIRCOB, Département de Chimie, Université de Versailles Saint‐Quentin en Yvelines, 45 avenue des Etats‐Unis, 78035 Versailles, France | Université Pierre et Marie Curie, 4 place Jussieu, boite 45, 75252 Paris, Cedex 05, France | Laboratoire de Cryptogamie, Muséum National d'Histoire Naturelle, 12 rue Buffon, 75005, Paris, France

Note: [] Corresponding author. Tel.: +331 39 25 44 54; Fax: +331 39 25 44 52; E‐mail: [email protected].

Abstract: This paper deals with the cytotoxic chaetoglobosins obtained from culture on maize of the strains ATCC 26115 and MRC 2654 of the fungus Phomopsis leptostromiformis. Both strains produced, in more or less important amounts, the known chaetoglobosins M (1) and N (2). In addition, the new chaetoglobosin O (3), was isolated from the ATCC 26115 strain and characterized by HRMS and 2D NMR experiments. With the MRC 2654 strain, a fungal metabolite 4, more polar than the chaetoglobosins M and N, was extracted and purified. Spectroscopic and chromatographic data of metabolite 4 led to its identification to the bridged chaetoglobosin named compound S, which previously has been obtained by intramolecular Michael reaction on the chaetoglobosin M. Moreover, a methylation under Williamson conditions of the chaetoglobosin 4 resulted in the formation of the trimethylated chaetoglobosin 5.

Journal: Spectroscopy, vol. 17, no. 4, pp. 725-734, 2003