Biosynthesis and characterization of 15N6-labeled Phomopsin A, a lupin associated mycotoxin produced by Diaporthe toxica.
The hepatotoxin Phomopsin A (PHO-A), a secondary metabolite mainly produced by the fungus Diaporthe toxica, occurs predominantly on sweet lupins. Along with the growing interest in sweet lupins for food and feed commodities, concerns have been raised about fungal infestations, and consequently, about the determination of PHO-A.
High performance liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) represents the most suitable analytical technique for sensitive and selective detection of mycotoxins including PHO-A. However, isotopic labeled substances are needed as internal standards for a reliable and convenient quantification.
As no isotope standard for PHO-A is currently available, a biosynthesis of fully 15N6-labeled PHO-A was established by cultivation of D. toxica on defined media containing Na15NO3 and 15N-labeled yeast extract as the only nitrogen sources. The identity of 15N6-PHO-A was confirmed by high resolution mass spectrometry.
The new 15N6-labeled standard will facilitate the method development for PHO-A including a more accurate quantification by LC-MS/MS.
Schloss S.; Wedell, I.; Koch, M.; Rohn, S.; Maul, R. 2015. Biosynthesis and characterization of 15N6-labeled Phomopsin A, a lupin associated mycotoxin produced by Diaporthe toxica. Food Chemistry 177, 61-65.