Natural Occurrence of Alternaria Toxins in Wheat-Based Products and Their Dietary Exposure in China.

Kai Zhao,Dajin Yang,Bing Shao,Fengqin Li,Jianghui Zhu,Aimin Zhang

doi:10.1371/journal.pone.0132019

Abstract

A total of 181 wheat flour and 142 wheat-based foods including dried noodle, steamed bread and bread collected in China were analyzed for alternariol (AOH), alternariol monomethyl ether (AME), tentoxin (TEN) and tenuazonic acid (TeA) by ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry. TeA was the predominant toxin found in 99.4% wheat flour samples at levels ranging from 1.76 μg/kg to 520 μg/kg. TEN was another Alternaria toxin frequently detected in wheat flour samples (97.2%) at levels between 2.72 μg/kg and 129 μg/kg. AOH and AME were detected in 11 (6.1%) samples at levels ranging from 16.0 μg/kg to 98.7 μg/kg (AOH) and in 165 (91.2%) samples with a range between 0.320 μg/kg and 61.8 μg/kg (AME). AOH was quantified at higher levels than AME with the ratio of AOH/AME ranging from 1.0 to 3.7. Significant linear regressions of correlation in toxin concentrations were observed between AOH and AME, AME and TeA, TEN and TeA, AOH+AME and TeA. At an average and 95th percentile, dietary exposure to AOH and AME in the Chinese general population and different age subgroups exceeded the relevant threshold value of toxicological concern (TTC), with the highest exposure found in children which deserves human health concern. TEN and TeA seem unlikely to be health concerns for the Chinese via wheat-based products but attention should be paid to synergistic or additive effects of TeA with AOH, AME, TEN and a further assessment will be performed once more data on toxicity-guided fractionation of the four toxins are available. It is necessary to conduct a systemic surveillance of Alternaria toxins in raw and processed foods in order to provide the scientific basis for making regulations on these toxins in China.

Highlights

Cereal grains are frequently infected by species of Alternaria that are capable of producing a number ofmycotoxins
tenuazonic acid (TeA) was the predominant Alternaria toxin in terms of either frequency or concentration, and it was detected in 99.4% (180/181) wheat flour samples at levels ranging from 1.76 μg/kg to 520 μg/kg
TeA, whether frequency or concentration, was the predominant Alternaria toxin detected in wheat flour and wheat-based foods, followed by TEN, AOH and alternariol monomethyl ether (AME)

Summary

Introduction

Cereal grains are frequently infected by species of Alternaria that are capable of producing a number ofmycotoxins. Alternaria Toxins in Chinese Wheat-Based Products characterized and have documented toxicity to animals can be grouped into three different structural classes: dibenzopyrone derivatives as in alternariol (AOH), alternariol monomethyl ether (AME), and altenuene (ALT); a tetramic acid derivative tenuazonic acid (TeA); and the perylene derivatives altertoxins I, II and III (ATX I, II and III) [1,2]. These toxins have been shown to have harmful effects in animals, including cytotoxic, fetotoxic and teratogenic activities [3]. Consumption of cereals invaded by Alternaria species and contaminated with associated mycotoxins was related to risk of human esophageal cancer in China [8]

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