Sensitive and selective alternariol analysis by a newly developed monoclonal antibody-based immunoassay

Alternariol is a toxic secondary metabolite produced by Alternaria fungi. Nowadays, this mycotoxin can be found in many products of plant origin at concerning concentrations. The aim of the present study was to develop a highly sensitive and selective immunochemical method for the analysis of alternariol. To this end, hapten synthesis was carried out from the scratch and specific high-affinity monoclonal antibodies to alternariol were generated by using, for the first time, alternariol bioconjugates with unambiguous linker tethering sites. A novel indirect enzyme-linked immunosorbent assay that incorporated a rationally designed heterologous conjugate was developed. The optimized assay showed an outstanding half-maximal inhibition concentration for alternariol below 0.04 ng/mL, and no cross-reactivity with alternariol monomethyl ether was observed. Very good recovery values and coefficients of variation were obtained from the analysis of alternariol-fortified fruit and cereal flour samples. Finally, alternariol was quantitatively determined in pears that had been previously infected with Alternaria alternata, showing excellent correlation with liquid chromatography results.

Pharmacokinetics and 28-day repeated-dose toxicity of enniatin B after oral administration in mice

Enniatins are emerging mycotoxins that contaminate foods. The present study investigated the oral pharmacokinetics and 28-day repeated-dose oral toxicity of enniatin B (ENNB) in CD1 (ICR) mice. In the pharmacokinetic study, male mice received a single oral or intravenous dose of ENNB [30 mg/kg body weight (BW) and 1 mg/kg BW, respectively]. After oral dosing, ENNB exhibited 139.9% bioavailability, a 5.1-hr elimination half-life, 5.26% fecal excretion from 4 to 24 h post-dose, and upregulation of Cyp7a1, Cyp2a12, Cyp2b10, and Cyp26a1 in the liver 2 h post-dosing. In the 28-day toxicity study, ENNB was administered to male and female mice by oral gavage at 0, 7.5, 15, and 30 mg/kg BW/day. Females (7.5 and 30 mg/kg) showed dose-unrelated decreased food consumption without accompanying changes in clinical parameters. Males (30 mg/kg) showed low red blood cell counts and high blood urea nitrogen levels and absolute kidney weights; however, other related parameters including the histopathology of systemic organs/tissues were unchanged. These results suggest that ENNB may not induce toxicity after 28 days of oral administration in mice, despite high absorption. The no-observed-adverse-effect level of ENNB after 28 days of repeated oral doses was 30 mg/kg BW/day for both sexes of mice.

Beauvericin: The beauty and the beast

Beauvericin (BEA) is a natural bioactive compound, with a dual nature. On the one hand, the peculiar characteristics of its molecule confer to BEA interesting properties, such as antibacterial, antiviral, antifungal, antiparasitic, insecticidal and anticarcinogenic activities. On the other hand, it is a natural contaminant of food and feed commodities, and an emerging mycotoxin, but lacks a toxicological risk assessment evaluation for long term exposure. This review aims to provide a global and comprehensive overview on BEA from its biological activities, to its in vivo and in vitro toxicological effects covering the multifaceted nature of this substance.

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

Alternaria molds can produce a variety of different mycotoxins, often resulting in food contamination with chemical mixtures, posing a challenge for risk assessment. Some of these metabolites possess estrogenic properties, an effect whose toxicological relevance is questioned in the light of the strong genotoxic and cytotoxic properties of co-occurring toxins. Thus, we tested a complex extract from A. alternata for estrogenic properties in Ishikawa cells. By assessing alkaline phosphatase activity, we did not observe estrogen receptor (ER) activation at non-cytotoxic concentrations (≤ 10 µg/ml). Furthermore, an extract stripped of highly genotoxic perylene quinones also did not mediate estrogenic effects, despite diminished genotoxic properties in the comet assay (≥ 10 µg/ml). Interestingly, both extracts impaired the estrogenicity of 17β-estradiol (E2) at non-cytotoxic concentrations (5-10 µg/ml), indicating anti-estrogenic effects which could not be explained by the presence of known mycoestrogens. A mechanism for this unexpected result might be the activation of the aryl hydrocarbon receptor (AhR) by Alternaria metabolites, as indicated by the induction of CYP1A1 transcription. While a direct influence on the metabolism of E2 could not be confirmed by LC-MS/MS, literature describing a direct interplay of the AhR with estrogenic pathways points to a corresponding mode of action. Taken together, the present study indicates AhR-mediated anti-estrogenic effects as a novel mechanism of naturally co-occurring Alternaria toxin mixtures. Furthermore, our results confirm their genotoxic activity and raise questions about the contribution of still undiscovered metabolites to toxicological properties.

Relationship between Fusarium spp. diversity and mycotoxin contents of mature grains in southern Belgium

Over a 4-year period (2010-13), a survey aiming at determining the occurrence of Fusarium spp. and their relations to mycotoxins in mature grains took place in southern Belgium. The most prevalent species were F. graminearum, F. avenaceum, F. poae and F. culmorum, with large variations between years and locations. An even proportion of mating type found for F. avenaceum, F. culmorum, F. cerealis and F. tricinctum is usually a sign of ongoing sexual recombination. In contrast, an unbalanced proportion of mating type was found for F. poae and no MAT1-2 allele was present in the F. langsethiae population. Genetic chemotyping indicates a majority of deoxynivalenol (DON)-producing strains in F. culmorum (78%, all 3-ADON producers) and F. graminearum (95%, mostly 15-ADON producers), while all F. cerealis strains belong to the nivalenol (NIV) chemotype. Between 2011 and 2013, DON, NIV, enniatins (ENNs) and moniliformin (MON) were found in each field in various concentrations. By comparison, beauvericin (BEA) was scarcely detected and T-2 toxin, zearalenone and α- and β-zearalenols were never detected. Principal component analysis revealed correlations of DON with F. graminearum, ENNs and MON with F. avenaceum and NIV with F. culmorum, F. cerealis and F. poae. BEA was associated with the presence of F. tricinctum and, to a lesser extent, with the presence of F. poae. The use of genetic chemotype data revealed that DON concentrations were mostly influenced by DON-producing strains of F. graminearum and F. culmorum, whereas the concentrations of NIV were influenced by the number of NIV-producing strains of both species added to the number of F. cerealis and F. poae strains. This study emphasises the need to pay attention to less-studied Fusarium spp. for future Fusarium head blight management strategies, as they commonly co-occur in the field and are associated with a broad spectrum of mycotoxins.