Jesús M. Gonzalez-Jartin

Yogurt, a milk-derived product, is susceptible to mycotoxin contamination. While various methods have been developed for the analysis of dairy products, only a few have been specifically validated for yogurt. In addition, these methods are primarily focus on detecting aflatoxins and zearalenone. This study aimed to conduct a preliminary investigation into the presence of regulated, emerging, and modified mycotoxins in natural and oat yogurts available in the Spanish market. For this, a QuEChERS-based extraction method was optimized and then validated to detect and quantify 32 mycotoxins using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The method was in-house validated for the analysis of natural and oat yogurt in terms of linearity, matrix effect, sensitivity, accuracy, and precision. Satisfactory performance characteristics were achieved; for most of the analytes, LOQs were lower than 2 ng/g, and recoveries ranged from 60 to 110% with a precision, expressed as the relative standard deviation of the recovery, lower than 15%. Subsequently, the validated method was applied to analyze commercial yogurt samples, revealing a notable incidence of beauvericin and enniatins, with some analogues found in up to 100% of the samples. Alternariol methyl ether was also frequently found, appearing in 50% of the samples. Additionally, the study identified regulated toxins such as fumonisins, ochratoxin A , and HT-2 toxin. These results provide new incidence data in yogurt, raising concerns about potential health risks for consumers.

Enniatins (ENNs) A1 and B1, previously considered ionophores, are emerging mycotoxins with effects on Ca²⁺ homeostasis. However, their exact mechanism of action remains unclear. This study investigated how these toxins affect Ca²⁺ flux in SH-SY5Y cells. ENN A1 induced Ca²⁺ influx through store-operated channels (SOC). The mitochondrial uncoupler FCCP reduced this influx, suggesting that the mitochondrial status influences the toxin effect. Conversely, ENN B1 did not affect SOC but acted on another Ca²⁺ channel, as shown when nickel, which directly blocks the Ca²⁺ channel pore, is added. Mitochondrial function also influenced the effects of ENN B1, as treatment with FCCP reduced toxin-induced Ca²⁺ depletion and uptake. In addition, both ENNs altered mitochondrial function by producing the opening of the mitochondrial permeability transition pore. This study describes for the first time that ENN A1 and B1 are not Ca²⁺ ionophores and suggests a different mechanism of action for each toxin.

Psammaplins are sulfur containing bromotyrosine alkaloids that have shown antitumor activity through the inhibition of class I histone deacetylases (HDACs). The cytotoxic properties of psammaplin A (1), the parent compound, are related to peroxisome proliferator-activated receptor γ (PPARγ) activation, but the mechanism of action of its analogs psammaplin K (2) and bisaprasin (3) has not been elucidated. In this study, the protective effects against oxidative stress of compounds 1-3, isolated from the sponge Aplysinella rhax, were evaluated in SH-SY5Y cells. The compounds improved cell survival, recovered glutathione (GSH) content, and reduced reactive oxygen species (ROS) release at nanomolar concentrations. Psammaplins restored mitochondrial membrane potential by blocking mitochondrial permeability transition pore opening and reducing cyclophilin D expression. This effect was mediated by the capacity of 1-3 to activate PPARγ, enhancing gene expression of the antioxidant enzymes catalase, nuclear factor E2-related factor 2 (Nrf2), and glutathione peroxidase. Finally, HDAC3 activity was reduced by 1-3 under oxidative stress conditions. This work is the first description of the neuroprotective activity of 1 at low concentrations and the mechanism of action of 2 and 3. Moreover, it links for the first time the previously described effects of 1 in HDAC3 and PPARγ signaling, opening a new research field for the therapeutic potential of this compound family.

Oxidative stress is a common pathological mechanism in neurodegenerative diseases. Aging leads to mitochondrial dysfunction and produces a reduction in endogenous antioxidant systems efficiency, with a consequent increase in reactive oxygen species (ROS) release. This unbalance among protecting and damaging molecules impairs neuronal function, even causing cell death. Therefore, the search for new drugs with antioxidant and neuroprotective effects is a great challenge. In this work, the bioactivity of three new cyclopeptides (1–3), isolated from the freshwater cyanobacterium Microcoleus autumnalis, was tested in SH-SY5Y human neuroblastoma cells. This species is a prolific source of bioactive metabolites, anatoxin being the best-characterized molecule due to its neurotoxicity. In this context, cytotoxicity of compounds was firstly analyzed. None of the M. autumnalis metabolites induced toxic effects up to 50 µM after 24 h of incubation. In view of the lack of neurotoxicity produced by compounds 1–3, their antioxidant and neuroprotective ability was analyzed. With this objective, SH-SY5Y cells were co-treated with compounds (0.001, 0.01, 0.1, and 1 µM) and 150 µM H₂O₂ for 6 h. The effect of compounds 1–3 on cell viability under oxidative stress conditions was determined, finding that the three compounds were able to protect neuronal cells from oxidative damage. Next, mitochondrial function was evaluated by monitoring mitochondrial membrane potential. In this assay, only compound 3 recovered the organelles from the depolarization generated by H₂O₂. Finally, intracellular ROS content was assessed, observing that 1–3 decreased the levels of these harmful molecules. In conclusion, M. autumnalis cyclopeptides presented neuroprotective effects mainly mediated by their ability to reduce ROS levels. These results suggest that compounds 1–3 act as direct antioxidants and could be interesting compounds for further studies in neurodegenerative diseases.

The presence of contaminants in water may involve a risk to human and animal health. Conventional water treatment methods such as coagulation, flocculation, and sedimentation are ineffective for cyanotoxin removal. In addition, high amounts of cyanotoxins can be released during those processes if cells lyse. Thus, new mitigation strategies must be developed to ameliorate the consequences of harmful algal blooms. In this sense, nanotechnology has become a promising tool for the treatment of contaminated water. Several nanomaterials with specific chemical affinities can be combined into hybrid structures, leading to nanostructured agents with a large surface area and with the ability to absorb different contaminants. In addition, these structures can include magnetite, which enables separation from the detoxified substance by magnetic extraction, which is considered a green technique. This approach has been successfully applied to the removal of dyes, endocrine disruptors, and heavy metal ions. Recently, we have described the use of carbon nanoparticles to remove around 60% of microcystins from contaminated solutions, but with a low efficiency in the adsorption of anatoxin-a and cylindrospermopsin. In this work, a new set of biocompatible magnetic nanocomposites were tested using artificially contaminated water. The toxin content in solutions was determined before and after treatment by ultra-performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS). With these new nanocomposites, cyanotoxin elimination was highly improved, reaching toxin removal rates of up 80%. Therefore, the implementation of the nanotechnology in water treatment could be a promising approach to reduce the presence of natural toxins in the water.