Masked fungal toxins in our food | Chemical & Engineering News
Volume 94 Issue 46 | p. 10 | Concentrates
Issue Date: November 21, 2016

Masked fungal toxins in our food

When pathogenic fungi leave poisons behind on harvests, the plant can modify the toxins, sidestepping food safety detection
Department: Science & Technology
Keywords: toxicology, mycotoxin, food, toxicology, agriculture, fungus
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Alternaria fungi (below) produce a toxin called alternariol, which can be conjugated with sulfate (blue) and glucoside (red) groups, pushing the poison off the radar of food safety monitors.
A structure of an alternariol sulfate glucoside.
 
Alternaria fungi (below) produce a toxin called alternariol, which can be conjugated with sulfate (blue) and glucoside (red) groups, pushing the poison off the radar of food safety monitors.
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Credit: J. Agric. Food Chem.
Image of Alternaria fungi.
 
Credit: J. Agric. Food Chem.

When fungi attack agricultural crops, they don’t just decrease yield, they can also leave behind poisonous compounds on the harvest. Although food safety scientists have long monitored these fungal products, known as mycotoxins, in recent years they’ve discovered that plants can chemically modify the compounds for their own survival, say, by adding a protective sugar group. However, food safety tests don’t currently look for these masked mycotoxins. Furthermore, the masked mycotoxins “may be hydrolyzed in the [human] digestive tract, thereby releasing the parental form and increasing the total exposure to the toxin,” notes a research team led by Sabine E. Kulling of the German Federal Research Institute of Nutrition & Food (J. Agric. Food Chem. 2016, DOI: 10.1021/acs.jafc.6b03120). Kulling and her colleagues report that when Alternaria alternata infects tomato cells, the fungus first decorates its toxins—including alternariol (shown)—with a sulfate group and then the tomato’s enzymes add a glucoside. Because monitoring only focuses on the parent toxin and not its metabolites, levels of mycotoxins such as alternariol in food might be much higher than previously thought. “If you don’t look for these conjugates, you have no chance of seeing them,” Kulling tells C&EN.

 
Chemical & Engineering News
ISSN 0009-2347
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