Investigating the interaction between organic anion transporter 1 and ochratoxin A: An in silico structural study to depict early molecular events of substrate recruitment and the impact of single point mutations

Organic anion transporters (OATs) belong to a subgroup of the solute carrier 22 transporter family. OATs have a central role in xenobiotic disposition affecting the toxicokinetics of its substrates and inter-individual differences in their expression, activity and function impact both toxicokinetics and toxicodynamics. Amongst OATs, OAT1 (solute carrier family 22 member 6) is involved in the urinary excretion of many xenobiotics bringing substrates into renal proximal tubular cells which can then be secreted across the apical membrane into the tubule lumen. The mycotoxin ochratoxin A has been shown to have a high affinity for OAT1, which is an important renal transporter involved in its urinary excretion. Nowadays, molecular modeling techniques are widely applied to assess protein-ligand interactions and may provide a tool to depict the mechanic of xenobiotic action be it toxicokinetics or toxicodynamics. This work provides a structured pipeline consisting of docking and molecular dynamic simulations to study OAT1-ligand interactions and the impact of OAT1 polymorphisms on such interactions. Such a computational structure-based analytical framework allowed to: i) model OAT1-substrate complex formation and depict the features correlating its sequence, structure and its capability to recruit substrates; and ii) investigate the impact of OAT1 missense mutations on substrate recruitment. Perspectives on applying such a structured pipeline to xenobiotic-metabolising enzymes are discussed

Assessing the Mycotoxin-related Health Impact of Shifting from Meat-based Diets to Soy-based Meat Analogues in a Model Scenario Based on Italian Consumption Data

The aim of this study was to assess the risk of replacing meat with plant-based analogues with respect to mycotoxin exposure, as a proof of concept to demonstrate the need for a proper regulatory framework for mycotoxins in meat imitates. Hence, we considered a full replacement of meat consumption with soy-based meat analogues and we evaluated the exposure to AFB1 and OTA, based on the Italian National Food Consumption Survey INRAN-SCAI 2005–2006 and the European Food Safety Authority occurrence data. The overall health impact from soy-based food consumption and a meat-free diet was quantified in terms of Disability-Adjusted Life Years (DALYs) in three different contamination and consumption scenarios. The substitution of meat products with soy-based imitates would prevent up to 406.2 colorectal cancer cases/year/country associated with 532 healthy years of life. However, we also determined an increased risk of liver cancer and loss of healthy life-years due to AFB1 exposure and a potential risk of renal cancer as due to an increased intake of OTA, leading up to 1208 extra cancer cases associated with the loss of 12,080 healthy life-years/country. Shifting to a plant-based diet actually eliminates a cancer risk factor such as processed meat, however, higher and unexpected risks could arise if mycotoxins are not properly regulated in plant-based meat alternatives. Taking into account the ubiquitous occurrence of mycotoxins, also in the light of climate change, and the growing trend toward plant-based meat analogues, greater importance should be given to actual food consumption trends and correlated with updated natural toxins regulations and risk assessments

Modulation of aflatoxin B1 cytotoxicity and aflatoxin M1 synthesis by natural antioxidants in a bovine mammary epithelial cell line

Aflatoxin (AF) B1, a widespread food and feed contaminant, is bioactivated by drug metabolizing enzymes (DME) to cytotoxic and carcinogenic metabolites like AFB1-epoxide and AFM1, a dairy milk contaminant. A number of natural antioxidants have been reported to afford a certain degree of protection against AFB1 (cyto)toxicity. As the mammary gland potentially participates in the generation of AFB1 metabolites, we evaluated the role of selected natural antioxidants (i.e. curcumin, quercetin and resveratrol) in the modulation of AFB1 toxicity and metabolism using a bovine mammary epithelial cell line (BME-UV1). Quercetin and, to a lesser extent, resveratrol and curcumin from Curcuma longa (all at 5 \u3bcM) significantly counteracted the AFB1-mediated impairment of cell viability (concentration range: 96\u2013750 nM). Moreover, quercetin was able to significantly reduce the synthesis of AFM1. The quantitative PCR analysis on genes encoding for DME (phase I and II) and antioxidant enzymes showed that AFB1 caused an overall downregulation of the detoxifying systems, and mainly of GSTA1, which mediates the GSH conjugation of the AFB1-epoxide. The negative modulation of GSTA1 was efficiently reversed in the presence of quercetin, which significantly increased GSH levels as well. It is suggested that quercetin exerts its beneficial effects by depressing the bio-transformation of AFB1 and counterbalancing its pro-oxidant effects

In vitro interactions of Alternaria mycotoxins, an emerging class of food contaminants, with the gut microbiota: a bidirectional relationship

The human gut microbiota plays an important role in the maintenance of human health. Factors able to modify its composition might predispose the host to the development of pathologies. Among the various xenobiotics introduced through the diet, Alternaria mycotoxins are speculated to represent a threat for human health. However, limited data are currently available about the bidirectional relation between gut microbiota and Alternaria mycotoxins. In the present work, we investigated the in vitro effects of different concentrations of a complex extract of Alternaria mycotoxins (CE; containing eleven mycotoxins; e.g. 0.153 µM alternariol and 2.3 µM altersetin, at the maximum CE concentration tested) on human gut bacterial strains, as well as the ability of the latter to metabolize or adsorb these compounds. Results from the minimum inhibitory concentration assay showed the scarce ability of CE to inhibit the growth of the tested strains. However, the growth kinetics of most of the strains were negatively affected by exposure to the various CE concentrations, mainly at the highest dose (50 µg/mL). The CE was also found to antagonize the formation of biofilms, already at concentrations of 0.5 µg/mL. LC–MS/MS data analysis of the mycotoxin concentrations found in bacterial pellets and supernatants after 24 h incubation showed the ability of bacterial strains to adsorb some Alternaria mycotoxins, especially the key toxins alternariol, alternariol monomethyl ether, and altersetin. The tendency of these mycotoxins to accumulate within bacterial pellets, especially in those of Gram-negative strains, was found to be directly related to their lipophilicity

Cleaning the Label of Cured Meat; Effect of the Replacement of Nitrates/Nitrites on Nutrients Bioaccessibility, Peptides Formation, and Cellular Toxicity of In Vitro Digested Salami

Curing salts composed of mixtures of nitrates and nitrites are preservatives widely used in processed meats. Despite many desirable technological effects, their use in meat products has been linked to methemoglobinemia and the formation of nitrosamines. Therefore, an increasing "anti-nitrite feeling" has grown among meat consumers, who search for clean label products. In this view, the use of natural compounds as alternatives represents a challenge for the meat industry. Processing (including formulation and fermentation) induces chemical or physical changes of food matrix that can modify the bioaccessibility of nutrients and the formation of peptides, impacting on the real nutritional value of food. In this study we investigated the effect of nitrate/nitrite replacement with a combination of polyphenols, ascorbate, and nitrate-reducing microbial starter cultures on the bioaccessibility of fatty acids, the hydrolysis of proteins and the release of bioactive peptides after in vitro digestion. Moreover, digested salami formulations were investigated for their impacts on cell proliferation and genotoxicity in the human intestinal cellular model (HT-29 cell line). The results indicated that a replacement of synthetic nitrates/nitrites with natural additives can represent a promising strategy to develop innovative "clean label" salamis without negatively affecting their nutritional value

Computations of gas-dynamic and plasma phenomena in a flowing partially-ionized gas

Imperial Users onl

Mechanisms of Fumonisin B1 Toxicity: A Computational Perspective beyond the Ceramide Synthases Inhibition

Fumonisins are mycotoxins produced by Fusarium fujikuroi species complex that may contaminate food and feed threatening human and animal health. Among the fumonisins group, fumonisin B1 is the most widespread and best characterized in terms of toxicity, while additional toxicological data on its congeners, such as N-acylated and hydrolyzed forms, need to be collected to support the group-based risk assessment. The inhibition of ceramide synthase has been identified as the key molecular mechanism of fumonisins toxicity resulting in modifications of sphingolipids rheostat. However, the existence of ancillary mechanisms and biological targets are likely to occur given the growing number of evidence reporting the multitarget mechanisms of mycotoxins toxicity. Therefore, in the framework of the early warning analysis of multitarget toxicity of fumonisins group, the present study aimed at searching potential targets for future hazard characterization studies of fumonisin B1 and its hydrolyzed and N-acetylated forms. In particular, on the basis of structural analogies with known inhibitors, the molecular interaction between N-acylated and hydrolyzed forms of fumonisin B1 and either ceramide transfer protein or sphingosine kinase I was assessed with a molecular modeling study. Our results pointed out that the molecular features of N-acylated hydrolyzed fumonisin B1 and hydrolyzed fumonisin B1 may allow the interaction with the ceramide transfer protein and with the sphingosine kinase I enzyme, respectively. Overall, our results identified such proteins as relevant targets that might take part in fumonisins group toxicity, adding plausible mechanistic insights to better understand fumonisins toxicity. Moreover, possible divergences in the mechanisms of action of fumonisin B1 and its modified forms were identified pointing out the need to assess their relevance with high priority to enhance the understanding of group toxicity

Risk–benefit assessment of shifting from traditional meat-based diets to alternative dietary patterns

The consumption of plant-based meat alternatives has recently transitioned from the niche market to the mainstream. However, changing the dietary patterns may lead to new health challenges referred to possible higher exposure to natural toxins found in plant-based food. The present project aimed to train the fellow in the field of chemical risk assessment and provide a comprehensive overview on how a change towards plant-based meat alternatives may represent a driver for emerging risks. Thus, within the EU-FORA programme the fellow engaged in the following activities: (i) perform a systematic review to analyse the distribution of natural toxins in the most common plant-based meat alternatives in Europe, (ii) risk–benefit assessment of shifting from meat-based diets to soy-based meat alternatives by modelling the substitution of meat with soy, and (iii) determine the occurrence of mycotoxins in plant-based meat alternatives from local markets in Parma, Italy. The fellow learnt the chemical risk assessment procedures applied by the researchers from the Department of Food and Drug of Parma University, thus gaining an in-depth expertise in all the steps. A risk–benefit assessment was performed modelling the intake of aflatoxin B1-contaminated soy-based meat analogues. The health impact due to intake of soy and exposure to aflatoxin B1 was estimated. Within the research group, the fellow also worked on developing a multi-mycotoxin determination method for plant-based meat alternatives matrices. The results of the project provide a picture reflecting the occurrence of natural toxins in plant-based meat alternatives and the need of upgraded regulation frameworks that take into account new products and dietary patterns. The EU-FORA fellowship was a great opportunity for the fellow to expand his professional network and increase his expertise in food safety by gaining new skills in chemical risk assessment, risk–benefit assessment and analytical chemistry