Anomericity of T-2 toxin-glucosides; masked mycotoxins in cereal crops

Authors: McCormick, Susan; KATO, TAKAYUKI - Wayne State University; Maragos, Chris; Busman, Mark; LATTANZIO, VERONICA - National Research Council - Italy; GALAVERNA, GIANNI - University Of Parma; DALL-ASTA, CHIARA - University Of Parma; CRICH, DAVID - Wayne State University; Price, Neil; Kurtzman, Cletus

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/18/2014
Publication Date: 12/18/2014
Publication URL: http://handle.nal.usda.gov/10113/60526
Citation: McCormick, S.P., Kato, T., Maragos, C.M., Busman, M., Lattanzio, V.M.T., Galaverna, G., Dall-Asta, C., Crich, D., Price, N.P.J., Kurtzman, C.P. 2014. Anomericity of T-2 toxin-glucosides; masked mycotoxins in cereal crops. Journal of Agricultural and Food Chemistry. 63(2):731-738.

Interpretive Summary: T-2 toxin is a trichothecene mycotoxin produced when the fungus Fusarium infects small grains, especially oats. Ingestion of T-2 toxin contaminated grain can cause diarrhea, hemorrhaging, and feed refusal. Plants infected with mycotoxin-producing fungi form sugar derivatives of toxins. These sugar derivatives, sometimes called masked mycotoxins, are a potential food safety concern because they are not detectable by standard approaches and may be converted back to the parent toxin during digestion or food processing. Development of improved methods for detection and assessment of the risk posed by these masked mycotoxins have been hindered by an inability to isolate or synthesize sufficient amounts of these masked toxins. This study found that the masked mycotoxin, T-2 toxin glucoside, found in contaminated grain was identical to that produced in a laboratory using Blastobotrys yeast cells. This study showed that this yeast method is an efficient way to produce T-2 toxin 3-glucoside that can be used to assess its toxicity and to develop new analytical methods for its detection and measurement. A commercial kit for detection of T-2 toxin was not effective for detection of T-2 toxin glucoside but a test developed to detect T-2 toxin glucoside also detects T-2 toxin. The stability of T-2 glucosides was tested with a human gut assay that mimics the human gastrointestinal process. Both glucosides as well as the parent T-2 toxin were significantly degraded after 24 hours.

Technical Abstract: T-2 toxin is a trichothecene mycotoxin produced when the fungus Fusarium infects small grains, especially oats. Ingestion of T-2 toxin contaminated grain can cause diarrhea, hemorrhaging, and feed refusal. Cereal crops infected with mycotoxin-producing fungi form toxin glycosides, sometimes called masked mycotoxins, which are a potential food safety concern because they are not detectable by standard approaches and may be converted back to the parent toxin during digestion or food processing. Masked glucoside forms of trichothecenes such as deoxynivalenol and T-2 toxin have been reported, but because it occurs at low concentration, the anomericity of T-2 toxin glucoside has not been determined. In this study T-2 toxin ß-glucoside was chemically synthesized and compared to T-2 toxin a-glucoside prepared with Blastobotrys muscicola cultures, and the T-2 toxin glucoside found in naturally contaminated oats and wheat. The anomeric forms were separated chromatographically and differ in both NMR and mass spectrometry. Neither T-2 glucoside was phytotoxic to the model plant alga Chlamydomonas reinhardtii. Both anomers were significantly degraded to T-2 and HT-2 under conditions that mimic human digestion, but with different kinetics and metabolic end products. Significantly, an antibody test for detection of T-2 toxin was not effective for detection of T-2 toxin a-glucoside. The naturally occurring T-2 toxin glucoside from plants was found to be identical to T-2 toxin a-glucoside prepared with B. muscicola. Importantly, this anomer was produced in sufficient quantity to assess its animal toxicity and to develop detection methods, should these be needed to regulate T-2 toxin glucoside in agricultural products.