Identification of the first fumonisin mycotoxins with three acyl groups by ESI-ITMS and ESI-TOFMS following RP-HPLC separation: palmitoyl, linoleoyl and oleoyl EFB₁ fumonisin isomers from a solid culture of Fusarium verticillioides.
The aim of this study was to apply RP-HPLC/ESI-ITMS and RP-HPLC/ESI-TOFMS to investigate and characterise six new higher molecular weight fumonisins (three pairs of isomers) extracted from a Fusarium verticillioides-infected solid rice culture. The ITMS and ITMS² spectra clearly indicated the m/z values (960, 984 and 986) of the protonated molecules and the FB₁ toxin-like structures of these compounds, respectively. Moreover, the data evaluation software of the TOFMS equipment unambiguously demonstrated the exact masses of the protonated molecules and the suggested empirical formulae (C₅₀H₈₉NO₁₆, C₅₂H₈₉NO₁₆ and C₅₂H₉₁NO₁₆) of the new fumonisins, with mass accuracy in the range between 0.1 and -1.1 ppm. Subtraction of the empirical formula of FB₁ toxin (C₃₄H₅₉NO₁₅) from these formulae and correction for the mass of water split-off from the fumonisin molecule during ester formation resulted in the empirical formulae of the fumonisin backbone esterifying agents (fatty acids): C₁₆H₃₂O₂ (palmitic acid, PA), C₁₈H₃₂O₂ (linoleic acid, LA) and C₁₈H₃₄O₂ (oleic acid, OA). We denoted the new compounds as esterified FB₁ (EFB₁) toxins, with the suggested names EFB₁ PA, iso-EFB₁ PA, EFB₁ LA, iso-EFB₁ LA, EFB₁ OA and iso-EFB₁ OA. The total amount of these new compounds comprised 0.1% of the FB₁ concentration, which may be rated as significant when it is considered that these new components are significantly more apolar than earlier-described fumonisins, and their uptake into and toxicity elicited in the various tissues of living organisms may therefore also be significantly different from those of other fumonisins.
Faculty of Engineering, University of Szeged, Szeged, Hungary. tibor.bartok@fumizol.hu
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D000215:Acylation; D002851:Chromatography, High Pressure Liquid; D056148:Chromatography, Reverse-Phase; D037341:Fumonisins / Q000737:chemistry* / Q000378:metabolism*; D005670:Fusarium / Q000254:growth & development / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D007536:Isomerism; D057230:Limit of Detection; D019787:Linoleic Acid / Q000737:chemistry / Q000378:metabolism*; D015394:Molecular Structure; D008970:Molecular Weight; D019301:Oleic Acid / Q000737:chemistry / Q000378:metabolism*; D012275:Oryza / Q000378:metabolism; D019308:Palmitic Acid / Q000737:chemistry / Q000378:metabolism*; D012639:Seeds / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry
D037341:Fumonisins; D019301:Oleic Acid; D019308:Palmitic Acid; C056933:fumonisin B1; D019787:Linoleic Acid