The fate of altertoxin II during tomato processing steps at a laboratory scale

Abstract

The emerging <i>Alternaria </i>mycotoxin altertoxin II demonstrated substantial genotoxicity <i>in vitro</i>. Ubiquitous <i>Alternaria ssp</i>. frequently infest various agricultural crops, leading to economic losses and also potential food safety issues caused by associated mycotoxin contaminations. Due to the lack of commercially available reference standards, data on the general chemical behavior, the occurrence and the biological/toxicological effects of altertoxin II are scarce. Since tomatoes are particularly prone to <i>Alternaria </i>infestations, we simulated the storage and food processing of intact tomatoes and purees after altertoxin II-addition. We observed significant decrease in altertoxin II concentrations during storage at room temperature and particularly under thermal stress, by employing a validated LC-MS/MS method. Moreover, the reduction to the compound’s epoxide group to the alcohol, i.e. the formation of altertoxin I, was determined at considerable ratios in intact tomato fruits suggesting effective enzymatic xenobiotic metabolism.<br>

Bioavailability, metabolism, and excretion of a complex Alternaria culture extract versus altertoxin II: a comparative study in rats

“…Due to interfering matrix effects, reliable quantitation of more than half of the ALP signals was not possible. However, these results are in line with previous in vivo (Puntscher et al 2019b) and in vitro studies demonstrating the highly reactive potential and low persistency of epoxide-holding perylene quinones (Aichinger et al 2018;Fleck et al 2014a, b;Puntscher et al 2019c). Of note, ATX-I was also determined in plasma, urine and fecal samples of rats receiving the isolated ATX-II (ATX-II group).…”

“…The respective concentrations were lower by a factor 5-10 compared to the samples of the extract group and partly below the LOQ (in plasma and in urine after 24 h). However, these results clearly suggest de-epoxidation of ATX-II in vivo resulting in the formation of ATX-I as suggested in in vitro models (Fleck et al 2014a, b) and for plant metabolism (Puntscher et al 2019c) before. In general, the enzymatic reduction of epoxides by mammalian epoxide hydrolases is known as a major detoxification mechanism (Decker et al 2009).…”

“…However, the precise mechanism of action has not been elucidated so far. In human cell lines (and tomato tissue in case of ATX-II), both compounds were found to be reduced to their alcohol analogues, ATX-I and ALP, respectively (Fleck et al 2014a, b;Puntscher et al 2019c). Moreover, significant degradation or chemical reactivity of ATX-II was determined in the presence of the natural food component and the flavonoid delphinidin (Aichinger et al 2018) and in tomato matrix (Puntscher et al 2019c).…”

Mycotoxins: Biotransformation and Bioavailability Assessment Using Caco-2 Cell Monolayer

“…( A ): Demethylation; ( B , C , H ): Hydroxylation; ( D , I ): Methylation; ( E , F ): Sulfation, glycosylation, and glucuronidation; ( G ): Epoxide reduction. CYP: Cytochrome P; and UGTs: Uridine 5′-diphospho-glucuronosyltransferase [ 71 , 117 , 121 , 172 , 173 , 174 , 177 , 178 , 179 , 180 , 181 ].…”

Naturally occurring mixtures of Alternaria toxins: anti-estrogenic and genotoxic effects in vitro

“…Another perylene quinone epoxide, STE-III, was recently described to impair DNA integrity to a comparable extent as ATX-II (Fleck et al 2016). However, these toxins are expected to be rather unstable under physiologic conditions (Aichinger et al 2018b) and during food processing (Puntscher et al 2018b). Thus, their toxicological relevance in vivo remains to be clarified.…”