|Englich, Ulrich -|
Submitted to: Acta Crystallographica Secion E
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 8, 2013
Publication Date: May 15, 2013
Citation: Englich, U., Krasnoff, S. 2013. Metacridamide B methanol-d4 monosolvate. Acta Crystallographica Secion E. E69:o742 DOI: 10.1107/S1600536813009641. Interpretive Summary: Metarhizium acridum is an insect pathogenic fungus that is known to be highly host specific to grasshoppers. The conidia of M. acridum are the active ingredient of several commercially produced biopesticides used for control of migratory locusts in Africa and Australia. We evaluated the chemical constituents of conidia with the aim of improving efficacy and shelf-life of formulated product and evaluating potential chemical risks associated with use of these fungi as biopesticides. We previously reported two novel compounds, metacridamides A and B, which showed moderate activity against cancer cell lines. In this study we report the crystal structure of metacridamide B which advances our knowledge of the types of compounds produced by this biocontrol fungus and sets the stage for studying their biological role.
Technical Abstract: The title compound was extracted from conidia of the fungus Metarhizium acridum. Crystals were obtained as a methanol-d4 solvate. The tail part of the 4-methylhexan-2-yl group exhibits disorder over two positions, with an occupancy ratio of 0.682 (9):0.318 (9). The crystal structure confirms the absolute configuration of nine stereocenters determined previously for the acetylated compound metacridamide A. In the crystal, the methanol-d4 molecule is positioned close to the O atom in the carbonyl group of the peptide bond, forming an O—H---O hydrogen bond. It also forms an O— H---O hydrogen bond with an adjacent molecule. N—H---O and O—H---O hydrogen bonds are observed between neighboring molecules.