title: Sulfoglucosides as Novel Modified Forms of the Mycotoxins Alternariol and Alternariol Monomethyl Ether.
abstract: The mycotoxins alternariol and alternariol-9-O-methyl ether have recently been reported to be extensively conjugated with glucose and malonyl glucose in tobacco suspension cells. However, only trace amounts of glucosylated conjugates were detected in tomatoes inoculated with Alternaria alternata in the present study. Instead, mostly sulfate conjugates were observed. In studies using cultures of A. alternata and incubations of alternariol and alternariol-9-O-methyl ether with tomato tissue in the absence of the fungus, it was clarified that sulfate conjugates were produced by the fungus, whereas tomato tissues converted alternariol and alternariol-9-O-methyl ether to glucosylated metabolites. Alternariol-3-sulfate, alternariol-9-sulfate, and alternariol-9-O-methyl ether-3-sulfate were unambiguously identified as fungal metabolites using MS and1H and13C NMR spectroscopy. When these sulfate conjugates were incubated with tobacco suspension cells or ex planta tomato tissues, three sulfoglucosides of alternariol and one sulfoglucoside of alternariol-9-O-methyl ether were formed. Using NMR spectroscopy, the chemical structures of alternariol-3-sulfate-9-glucoside, alternariol-9-sulfate-3-glucoside, and alternariol-9-O-methyl ether-3-sulfate-7-glucoside were established. These conjugates were also detected in the A. alternata-inoculated tomato. This is the first report on a mixed sulfate/glucoside diconjugate of a mycotoxin. Diconjugates of this novel type may be formed by all mycotoxins and their phase I metabolites with two or more hydroxyl groups and should be taken into account in the future analysis of modified mycotoxins.
authors: Department of Safety and Quality of Fruits and Vegetables, Max Rubner-Institut, Federal Research Institute of Nutrition and Food , Haid-und-Neu-Straße 9, 76131 Karlsruhe, Germany.
authors: Sebastian T
authors: ST
authors: Soukup
authors: Institute of Applied Biosciences, Department of Food Chemistry and Phytochemistry, Karlsruhe Institute of Technology (KIT) , Adenauerring 20a, 76131 Karlsruhe, Germany.
authors: Beate N
authors: BN
authors: Kohn
authors: Institute of Applied Biosciences, Department of Food Chemistry and Phytochemistry, Karlsruhe Institute of Technology (KIT) , Adenauerring 20a, 76131 Karlsruhe, Germany.
authors: Erika
authors: E
authors: Pfeiffer
authors: Department of Safety and Quality of Fruits and Vegetables, Max Rubner-Institut, Federal Research Institute of Nutrition and Food , Haid-und-Neu-Straße 9, 76131 Karlsruhe, Germany.
authors: Rolf
authors: R
authors: Geisen
authors: Institute of Applied Biosciences, Department of Food Chemistry and Phytochemistry, Karlsruhe Institute of Technology (KIT) , Adenauerring 20a, 76131 Karlsruhe, Germany.
authors: Manfred
authors: M
authors: Metzler
authors: Institute of Applied Biosciences, Department of Food Chemistry and Phytochemistry, Karlsruhe Institute of Technology (KIT) , Adenauerring 20a, 76131 Karlsruhe, Germany.
authors: Mirko
authors: M
authors: Bunzel
authors: Department of Safety and Quality of Fruits and Vegetables, Max Rubner-Institut, Federal Research Institute of Nutrition and Food , Haid-und-Neu-Straße 9, 76131 Karlsruhe, Germany.
authors: Sabine E
authors: SE
authors: Kulling
mesh_terms: D000528:Alternaria / Q000737:chemistry / Q000378:metabolism*; D007783:Lactones / Q000737:chemistry* / Q000378:metabolism; D015394:Molecular Structure; D009183:Mycotoxins / Q000737:chemistry* / Q000378:metabolism; D014026:Nicotiana / Q000378:metabolism / Q000382:microbiology*
chemical_list: D007783:Lactones; D009183:Mycotoxins; C005197:alternariol; C018206:alternariol monomethyl ether
keywords: Alternaria toxins; masked mycotoxins; modified mycotoxins; sulfates; sulfoglucosides