ESI-MS and MS/MS identification of the first ceramide analogues of fumonisin B sub(1) mycotoxin from a Fusarium verticillioides culture following RP-HPLC separation

• Published in: Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment Vol. 30; no. 9; pp. 1651 - 1659
• Main Authors: Bartok, T, Szecsi, A, Juhasz, K, Bartok, M, Mesterhazy, A
• Format: Journal Article
• Language: English
• Published: 01.09.2013
• Subjects: Fusarium verticillioides; Oryza sativa
• ISSN: 1944-0049; 1944-0057
• DOI: 10.1080/19440049.2013.809626

Following the earlier detection of six new esterified fumonisin B sub(1) (EFB sub(1)) isomers containing three acyl groups in a Fusarium verticillioides-inoculated rice culture, it was assumed that linoleic, palmitic or oleic acid esterifies one of the free OH groups on the fumonisin backbone. On the basis of the results of our recent investigations we now propose that these EFB sub(1) isomers are actually 3-O- and 5-O-acyl derivatives of FB sub(1) (3-O-linoleoyl-FB sub(1), 5-O-linoleoyl-FB sub(1), 3-O-palmitoyl-FB sub(1), 5-O-palmitoyl-FB sub(1), 3-O-oleoyl-FB sub(1) and 5-O-oleoyl-FB sub(1)). A F. verticillioides strain was identified that produced not only O-acyl-FB sub(1) isomers, but also low amounts of three N-acyl derivatives (N-linoleoyl-FB sub(1), N-palmitoyl-FB sub(1) and N-oleoyl-FB sub(1)), which eluted from the HPLC column after the six O-acyl compounds and in the same sequence as for the O-acyl compounds. The characteristic positive and negative ESI-MS/MS spectra obtained after solid-phase extraction of the culture extract facilitated identification of these N-acyl-FB sub(1) derivatives. The biosynthesis of N-palmitoyl-FB sub(1) by F. verticillioides was verified by spiking the culture extract with synthetic N-palmitoyl-FB sub(1). This is the first report of the separation and mass spectrometric identification of the six O-acyl- and three N-acyl-FB sub(1) derivatives extracted from a F. verticillioides culture.