Quantitation of Six Alternaria Toxins in Infant Foods Applying Stable Isotope Labeled Standards

Abstract

Alternaria fungi are widely distributed saprophytes and plant pathogens. As pathogens, Alternaria fungi infect crops and vegetables and cause losses in the fields and during postharvest storage. While farmers suffer from declining yields, consumers are endangered by the formation of secondary metabolites, because some of these exhibit a pronounced toxicological potential. The evaluation of the toxicological capabilities is still ongoing and will contribute to a valid risk assessment. Additionally, data on the incidence and the quantity of Alternaria mycotoxins found in food products is necessary for dietary exposure evaluations. A sensitive LC-MS/MS method for the determination of the Alternaria mycotoxins alternariol (AOH), alternariol monomethylether (AME), tentoxin (TEN), altertoxin I (ATX I), alterperylenol (ALTP), and tenuazonic acid (TA) was developed. AOH, AME, and TA were quantified using stable-isotopically labeled standards. TEN, ATX I, and ALTP were determined using matrix matched calibration. The developed method was validated by using starch and fresh tomato matrix and resulted in limits of detection ranging from 0.05 to 1.25 μg/kg for starch (as a model for cereals) and from 0.01 to 1.36 μg/kg for fresh tomatoes. Limits of quantification were determined between 0.16 and 4.13 μg/kg for starch and between 0.02 and 5.56 μg/kg for tomatoes. Recoveries varied between 83 and 108% for starch and between 95 and 111% for tomatoes. Intra-day precisions were below 4% and inter-day precisions varied from 3 to 8% in both matrices. Various cereal based infant foods, jars containing vegetables and fruits as well as tomato products for infants were analyzed for Alternaria mycotoxin contamination (n = 25). TA was the most frequently determined mycotoxin and was detected in much higher contents than the other toxins. AME and TEN were quantified in many samples, but in low concentrations, whereas AOH, ATX I, and ALTP were determined rarely, among which AOH had higher concentration. Some infant food products were highly contaminated with Alternaria mycotoxins and the consumption of these individual products might pose a risk to the health of infants. However, when the mean or median is considered, no toxicological risk was obvious.

Fullerol C60(OH)24 Nanoparticles Affect Secondary Metabolite Profile of Important Foodborne Mycotoxigenic Fungi In Vitro

“…Tenuazonic acid (Figure 4c) belongs to a group of tetramic acid derivatives and is acutely toxic (LD 50 81-225 mg kg −1 BW; mice). It is produced as a virulence factor to facilitate the colonisation of the fungus on plants since it inhibits protein biosynthesis by suppressing the release of new proteins from the ribosomes [41]. All of the mentioned A. alternata metabolites detected after growth in RPMI 1640 media were decreased in concentration after FNP was added to the growth media.…”

Comprehensive Analysis of the Alternaria Mycobolome Using Mass Spectrometry Based Metabolomics

“…In addition to the non‐targeted analysis of fungal extracts, the identification and quantification of the mycotoxins AOH, AME, ATX I, ATX II, ALTP, STTX III, TEN, and TA were complemented by targeted LC‐MS/MS analysis. The mycotoxins were compared to reference compounds and were identified based on retention times and mass transitions . A chromatogram of AOH, AME, ATX I, ATX II, ALTP, STTX III, and TEN is displayed in Figure S1a, Supporting Information.…”

“…TA and TEN are non‐genotoxic and the estimated chronic dietary exposure did not reach the TTC value of 1500 ng kg −1 body weight per day . However, recent studies, particularly on infant foods, highlighted that these TTC values were exceeded and required the establishment of a legal limit for TA in food products for infants …”

“…Assigned molecular formulae are intended to be allocated to metabolites using the Antibase and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases. Complementing this non‐targeted FTICR‐MS approach with targeted LC‐MS/MS analysis will help to clearly identify Alternaria mycotoxins, as LC‐MS/MS offers advantages in selectivity and the possibility to chromatographically separate isomers such as ATX II and ALTP. Additionally, the LC‐MS/MS measurements are intended to provide quantitative results on intra‐ and extracellular mycotoxin contents.…”

Determination of Alternaria Toxins in Sunflower Oil by Liquid Chromatography Isotope Dilution Tandem Mass Spectrometry

“…High ME (mainly ion suppression) usually influences the mycotoxin analysis based on the LC-MS/MS method [40,41] that is also true for Alternarias [8,9,13,18,19,23,28,29,31,42]. The lower sensitivity of our instrument and the high ME for AOH and AME increased the LOQ.…”