A target fishing study to spot possible biological targets of fusaric acid: Inhibition of protein kinase-A and insights on the underpinning mechanisms

Computational methods meet in vitro techniques: A case study on fusaric acid and its possible detoxification through cytochrome P450 enzymes

Mycotoxins are known environmental pollutants that may contaminate food and feed chains. Some mycotoxins are regulated in many countries to limit the trading of contaminated and harmful commodities. However, the so-called emerging mycotoxins are poorly understood and need to be investigated further. Fusaric acid is an emerging mycotoxin, noxious to plants and animals, but is known to be less toxic to plants when hydroxylated. The detoxification routes effective in animals have not been elucidated yet. In this context, this study integrated in silico and in vitro techniques to discover potential bioremediation routes to turn fusaric acid to its less toxic metabolites. The toxicodynamics of these forms in humans have also been addressed. An in silico screening process, followed by molecular docking and dynamics studies, identified CYP199A4 from the bacterium Rhodopseudomonas palustris HaA2 as a potential fusaric acid biotransforming enzyme. Its activity was confirmed in vitro. However, the effect of hydroxylation seemed to have a limited impact on the modelled toxicodynamics against human targets. This study represents a starting point to develop a hybrid in silico/in vitro pipeline to find bioremediation agents for other food, feed and environmental contaminants.

Free fatty acid receptors beyond fatty acids: A computational journey to explore peptides as possible binders of GPR120

Free fatty acids receptors, with members among G protein-coupled receptors (GPCRs), are crucial for biological signaling, including the perception of the so called "fatty taste". In recent years, GPR120, a protein belonging to the GPCR family, drew attention as an interesting pharmacological target to cope with obesity, satiety and diabetes. Apart from long chain fatty acids, which are GPR120 natural agonists, other synthetic molecules were identified as agonists expanding the chemical space of GPR120's ligands. In this scenario, we unveiled peptides as possible GPR120 binders toward a better understanding of this multifaceted and relevant target. This study analyzed a virtual library collecting 531 441 low-polar hexapeptides, providing mechanistic insights on the GPR120 activation and further extending the possible chemical space of GPR120 agonists. The computational pipeline started with a narrow filtering of hexapeptides based on their chemical similarity with known GPR120 agonists. The best hits were tested through docking studies, molecular dynamics and umbrella sampling simulations, which pointed to G[I,L]FGGG as a promising GPR120 agonist sequence. The presence of both peptides in food-related proteins was thoroughly assessed, revealing they may occur in mushrooms, food-grade bacteria and rice. Simulations on the counterparts with D-amino acids were also performed. Umbrella sampling simulations described that GdIFGGG may have a better interaction compared to its all-L counterpart (-13 kCal/mol ΔG and -6 kCal/mol ΔG, respectively). Overall, we obtained a predictive model to better understand the underpinning mechanism of GPR120-hexapeptides interaction, hierarchizing novel potential agonist peptides for further analysis and describing promising food sources worth of further dedicated investigations.

Virtual display of targets: A new level to rise the current understanding of ochratoxin A toxicity from a molecular standpoint

Ochratoxin A (OTA) is a mycotoxin spread worldwide contaminating several food and feed commodities and rising concerns for humans and animals. OTA toxicity has been thoroughly assessed over the last 60 years revealing a variety of adverse effects, including nephrotoxicity, hepatotoxicity and possible carcinogenicity. However, the underpinning mechanisms of action have yet to be completely displayed and understood. In this framework, we applied a virtual pipeline based on molecular docking, dynamics and umbrella simulations to display new OTA potential targets. The results collected consistently identified OGFOD1, a key player in protein translation, as possibly inhibited by OTA and its 2'R diastereomer. This is consistent with the current knowledge of OTA's molecular toxicology and may fill some gaps from a mechanistic standpoint. This could pave the way for further dedicated analysis focusing their attention on the OTA-OGFOD1 interaction, expanding the current understanding of OTA toxicity at a molecular level.

Autophagy modulation changes mechano-chemical sensitivity of T24 bladder cancer cells

Bladder cancer cells possess unique adaptive capabilities: shaped by their environment, cells face a complex chemical mixture of metabolites and xenobiotics accompanied by physiological mechanical cues. These responses might translate into resistance to chemotherapeutical regimens and can largely rely on autophagy. Considering molecules capable of rewiring tumor plasticity, compounds of natural origin promise to offer valuable options. Fungal derived metabolites, such as bafilomycin and wortmannin are widely acknowledged as autophagy inhibitors. Here, their potential to tune bladder cancer cells´ adaptability to chemical and physical stimuli was assessed. Additionally, dietary occurring mycotoxins were also investigated, namely deoxynivalenol (DON, 0.1-10 µM) and fusaric acid (FA, 0.1-1 mM). Endowing a Janus' face behavior, DON and FA are on the one side described as toxins with detrimental health effects. Concomitantly, they are also explored experimentally for selective pharmacological applications including anticancer activities. In non-cytotoxic concentrations, bafilomycin (BAFI, 1-10 nM) and wortmannin (WORT, 1 µM) modified cell morphology and reduced cancer cell migration. Application of shear stress and inhibition of mechano-gated PIEZO channels reduced cellular sensitivity to BAFI treatment (1 nM). Similarly, for FA (0.5 mM) PIEZO1 expression and inhibition largely aligned with the modulatory potential on cancer cells motility. Additionally, this study highlighted that the activity profile of compounds with similar cytotoxic potential (e.g. co-incubation DON with BAFI or FA with WORT) can diverge substantially in the regulation of cell mechanotransduction. Considering the interdependence between tumor progression and response to mechanical cues, these data promise to provide a novel viewpoint for the study of chemoresistance and associated pathways.

The bitter side of toxicity: A big data analysis spotted the interaction between trichothecenes and bitter receptors

The bitter taste perception evolved in human and animals to rapidly perceive and avoid potential toxic compounds. This is mediated by taste receptors type 2 (TAS2R), expressed in various tissues, which recently proved to be involved in roles beyond the bitter perception itself. With this study, the interaction between food-related toxic compounds and TAS2R46 has been investigated via computational approaches, starting with a virtual screening and moving to molecular docking and dynamics simulations. The virtual screening analysis identified trichothecolone and the trichothecenes class it belongs to, which includes mycotoxins widespread in several commodities raising food safety concerns, as possible TAS2R46 binders. Molecular docking and dynamics simulations were performed to further explore the trichotecenes-TAS2R46 interaction. The results indicated that deoxynivalenol and its 15-acetylated derivative could activate TAS2R46. Eventually, this study provided initial evidence supporting the involvement of TAS2R46 in the underpinning mechanisms of deoxynivalenol action highlighting the need of digging into the involvement of TAS2R46 and TAS2Rs in the adverse effects of deoxynivalenol and congeners.

In silico study on the Hepatitis E virus RNA Helicase and its inhibition by silvestrol, rocaglamide and other flavagline compounds

Hepatitis E Virus (HEV) follows waterborne or zoonotic/foodborne transmission. Genotype 3 HEV infections are worldwide spread, especially in swine populations, representing an emerging threat for human health, both for farm workers and pork meat consumers. Unfortunately, HEV in vitro culture and analysis are still difficult, resulting in a poor understanding of its biology and hampering the implementation of counteracting strategies. Indeed, HEV encodes for only one non-structural multifunctional and multidomain protein (ORF1), which might be a good candidate for anti-HEV drugging strategies. In this context, an in silico molecular modelling approach that consisted in homology modelling to derive the 3D model target, docking study to simulate the binding event, and molecular dynamics to check complex stability over time was used. This workflow succeeded to describe ORF1 RNA Helicase domain from a molecular standpoint allowing the identification of potential inhibitory compounds among natural plant-based flavagline-related molecules such as silvestrol, rocaglamide and derivatives thereof. In the context of scouting potential anti-viral compounds and relying on the outcomes presented, further dedicated investigations on silvestrol, rocaglamide and a promising oxidized derivative have been suggested. For the sake of data reproducibility, the 3D model of HEV RNA Helicase has been made publicly available.