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The cyclic depsipeptide mycotoxins beauvericin and enniatins are capable of reaching the systemic circulation through various routes of exposure and are hence capable of exerting central nervous system (CNS) effects, if they are able to pass the blood-brain barrier (BBB), which was the main objective of this study. Quantification of the mycotoxins was performed using an in-house developed and validated bio-analytical UHPLC-MS/MS method. Prior to the BBB experiments, the metabolic stability of the mycotoxins was evaluated in vitro in mouse serum and brain homogenate. The BBB permeation kinetics of beauvericin and enniatins were studied using an in vivo mice model, applying multiple time regression for studying the blood-to-brain influx. Additionally, capillary depletion was applied to obtain the fraction of the peptides really entering the brain parenchyma and the fraction loosely adhered to the brain capillary wall. Finally, also the brain-to-blood efflux transport kinetics was studied. Metabolic stability data indicated that the investigated mycotoxins were stable during the duration of the in vivo study. The brain influx study showed that beauvericin and enniatins are able to cross the blood-brain barrier in mice: using the Gjedde-Patlak biphasic model, it was shown that all investigated mycotoxins exert a high initial influx rate into the brain (K1 ranging from 11 to 53μL/(g×min)), rapidly reaching a plateau. After penetration, the mycotoxins reached the brain parenchyma (95%) with only a limited amount residing in the capillaries (5%). Negligible efflux (<0.005min(-1)) from the brain was observed in the 15min post-intracerebroventricular injection., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Currently, dermal exposure data of cyclic depsipeptide mycotoxins are completely absent. There is a lack of understanding about the local skin and systemic kinetics and effects, despite their widespread skin contact and intrinsic hazard. Therefore, we provide a quantitative characterisation of their dermal kinetics. The emerging mycotoxins enniatins (ENNs) and beauvericin (BEA) were used as model compounds and their transdermal kinetics were quantitatively evaluated, using intact and damaged human skin in an in vitro Franz diffusion cell set-up and ultra high-performance liquid chromatography (UHPLC)-MS analytics. We demonstrated that all investigated mycotoxins are able to penetrate through the skin. ENN B showed the highest permeation (kp,v=9.44 × 10(-6) cm/h), whereas BEA showed the lowest (kp,v=2.35 × 10(-6) cm/h) and the other ENNs ranging in between. Combining these values with experimentally determined solubility data, Jmax values ranging from 0.02 to 0.35 μg/(cm(2) h) for intact skin and from 0.07 to 1.11 μg/(cm(2) h) for damaged skin were obtained. These were used to determine the daily dermal exposure (DDE) in a worst-case scenario. On the other hand, DDE's for a typical occupational scenario were calculated based on real-life mycotoxin concentrations for the industrial exposure of food-related workers. In the latter case, for contact with intact human skin, DDE's up to 0.0870 ng/(kg BW × day) for ENN A were calculated, whereas for impaired skin barrier this can even rise up to 0.3209 ng/(kg BW × day) for ENN B1. This knowledge is needed for the risk assessment after skin exposure of contaminated food, feed, indoor surfaces and airborne particles with mycotoxins.

Fusafungine, a mixture of the cyclic hexadepsipeptides enniatins, is currently on the market for the treatment of upper respiratory tract diseases because of its bacteriostatic and anti-inflammatory effects. In this study, a quality-by-design risk assessment was performed with two objectives: (i) investigate whether enniatins are able to permeate the mucosa and reach blood circulation, as the summary of product characteristics indicates this is not the case, and if so, to quantify their transmucosal kinetics and (ii) study the influence of excipient concentration variability on mucosal permeation. First, the concentration of the two main excipients isopropyl myristate and ethanol, known penetration enhancers, in several marketed samples was determined using GC-FID. Then, the transmucosal kinetics of the enniatins were quantitatively evaluated for different dose solutions, using porcine buccal mucosa in an ex-vivo in-vitro Franz diffusion cell set-up, with UHPLC-MS/MS bioanalytics. This study demonstrated that enniatins are capable of permeating the mucosa. However, no risk of a significant different transmucosal permeability with varying excipient concentrations was detected., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Currently, dermal exposure data of cyclic depsipeptide mycotoxins beauvericin and enniatins are completely absent with a lack of local skin and systemic kinetics, despite their widespread skin contact and intrinsic hazard. Therefore a sensitive and specific bioanalytical high-throughput UHPLC-MS/MS method was developed for the quantitative and simultaneous determination of cyclic depsipeptide mycotoxins beauvericin and enniatins (A, A1, B, B1, D, E, C/F) in human skin Franz diffusion cell samples. The limits of detection ranged between 10 and 17pg/ml, while the total run time was only 4.5min. There was no significant effect of endogenous skin compounds on the mycotoxin MS signal observed, and the accuracy (0.68-24.68% bias) and precision (0.57-10.70% RSD) were considered acceptable for our purposes. Moreover, it was demonstrated that these cyclic depsipeptides are stable for at least 7 days when formulated in different organic or aqueous mixtures. Finally, adsorption to glass did occur: at least 50% ethanol or acetonitrile is required to prevent significant adsorption effects, which could be as high as 45%., (Copyright © 2014 Elsevier B.V. All rights reserved.)