Publications by authors named "William Dudefoi"

5 Publications

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digestion of food grade TiO (E171) and TiO nanoparticles: physicochemical characterization and impact on the activity of digestive enzymes.

Food Funct 2021 Jul;12(13):5975-5988

INRAE, UR1268 Biopolymères Interactions Assemblages, 44300 Nantes, France.

Titanium dioxide is a food additive that has raised some concerns for humans due to the presence of nanoparticles. We were interested in knowing the fate of TiO2 particles in the gastro-intestinal tract and their potential effect on digestive enzymes. For this purpose, we analysed the behaviour of two different food grade TiO2 samples (E171) and one nano-sized TiO2 sample (P25) through a standardized static in vitro digestion protocol simulating the oral, gastric and intestinal phases with appropriate juices including enzymes. Both E171 and P25 TiO2 particles remained intact in the digestive fluids but formed large agglomerates, and especially in the intestinal fluid where up to 500 μm sized particles have been identified. The formation of these agglomerates is mediated by the adsorption of mainly α-amylase and divalent cations. Pepsin was also identified to adsorb onto TiO2 particles but only in the case of silica-covered E171. In the salivary conditions, TiO2 exerted an inhibitory action on the enzymatic activity of α-amylase. The activity was reduced by a factor dependent on enzyme concentrations (up to 34% at 1 mg mL-1) but this inhibitory effect was reduced to hardly 10% in the intestinal fluid. In the gastric phase, pepsin was not affected by any form of TiO2. Our results hint that food grade TiO2 has a limited impact on the global digestion of carbohydrates and proteins. However, the reduced activity specifically observed in the oral phase deserves deeper investigation to prevent any adverse health effects related to the slowdown of carbohydrate metabolism.
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http://dx.doi.org/10.1039/d1fo00499aDOI Listing
July 2021

Evaluation of the effect of silver and silver nanoparticles on the function of selenoproteins using an in-vitro model of the fish intestine: The cell line RTgutGC.

Ecotoxicol Environ Saf 2021 Mar 17;211:111930. Epub 2021 Jan 17.

Department of Integrative Biology, Oklahoma State University, Stillwater, OK, USA. Electronic address:

Emerging research in mammalian cells suggests that ionic (AgNO) and nano silver (AgNP) can disrupt the metabolism of selenium which plays a vital role in oxidative stress control. However, the effect of silver (Ag) on selenoprotein function in fish is poorly understood. Here we evaluate the effects of AgNO and citrate coated AgNP (cit-AgNP) on selenoprotein function and oxidative stress using a fish cell line derived from the rainbow trout (Oncorhynchus mykiss) intestine (RTgutGC). Cell viability was evaluated using a cytotoxicity assay which measures simultaneously metabolic activity, membrane integrity and lysosome integrity. Cells exposed to equimolar amounts of AgNO and cit-AgNP accumulated the same amount of silver intracellularly, however AgNO was more toxic than cit-AgNP. Selenoenzymes glutathione peroxidase (GPx) and thioredoxin reductase (TrxR) mRNA levels and enzyme activity were measured. While mRNA levels remained unaffected by AgNO or cit-AgNP, the enzyme activity of GPx was inhibited by AgNO (1 µM) and cit-AgNP (5 µM) and TrxR activity was inhibited by AgNO (0.4 µM) and cit-AgNP (1, 5 µM). Moreover, cells exposed to 1 µM of AgNO and cit-AgNP showed an increase in metallothionein b (MTb) mRNA levels at 24 h of exposure, confirming the uptake of silver, but returned to control levels at 72 h suggesting silver scavenging by MTb. Oxidative stress was not observed at any of the doses of AgNO or cit-AgNP tested. Overall, this study shows that AgNO or cit-AgNP can inhibit the activity of selenoenzymes but do not induce oxidative stress in RTgutGC cells.
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http://dx.doi.org/10.1016/j.ecoenv.2021.111930DOI Listing
March 2021

Evaluation of the content of TiO nanoparticles in the coatings of chewing gums.

Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2018 Feb 20;35(2):211-221. Epub 2017 Oct 20.

a UR1268 BIA (Biopolymères Interactions Assemblages), INRA , Nantes , France.

Titanium dioxide is a metal oxide used as a white pigment in many food categories, including confectionery. Due to differences in the mass fraction of nanoparticles contained in TiO, the estimated intakes of TiO nanoparticles differ by a factor of 10 in the literature. To resolve this problem, a better estimation of the mass of nanoparticles present in food products is needed. In this study, we focused our efforts on chewing gum, which is one of the food products contributing most to the intake of TiO. The coatings of four kinds of chewing gum, where the presence of TiO was confirmed by Raman spectroscopy, were extracted in aqueous phases. The extracts were analysed by transmission electron microscopy (TEM), X-ray diffraction, Fourier Transform Raman spectroscopy, and inductively coupled plasma atomic emission spectroscopy (ICP-AES) to establish their chemical composition, crystallinity and size distribution. The coatings of the four chewing gums differ chemically from each other, and more specifically the amount of TiO varies from one coating to another. TiO particles constitute the entire coating of some chewing gums, whereas for others, TiO particles are embedded in an organic matrix and/or mixed with minerals like calcium carbonate, talc, or magnesium silicate. We found 1.1 ± 0.3 to 17.3 ± 0.9 mg TiO particles per piece of chewing gum, with a mean diameter of 135 ± 42 nm. TiO nanoparticles account for 19 ± 4% of all particles, which represents a mass fraction of 4.2 ± 0.1% on average. The intake of nanoparticles is thus highly dependent on the kind of chewing gum, with an estimated range extending from 0.04 ± 0.01 to 0.81 ± 0.04 mg of nano-TiO per piece of chewing gum. These data should serve to refine the exposure scenario.
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http://dx.doi.org/10.1080/19440049.2017.1384576DOI Listing
February 2018

Impact of food grade and nano-TiO particles on a human intestinal community.

Food Chem Toxicol 2017 Aug 28;106(Pt A):242-249. Epub 2017 May 28.

Department of Biology, Queen's University, Kingston ON K7L 3N6, Canada; Department of Biomedical and Molecular Sciences, School of Environmental Studies, Queen's University, Kingston, ON K7L 3N6, Canada. Electronic address:

Titanium dioxide (TiO) nanoparticles (NPs) are used as an additive (E171 or INS171) in foods such as gum, candy and puddings. To address concerns about the potential hazardous effects of ingested NPs, the toxicity of these food-grade NPs was investigated with a defined model intestinal bacterial community. Each titania preparation (food-grade TiO formulations, E171-1 and E171-6a) was tested at concentrations equivalent to those found in the human intestine after sampling 1-2 pieces of gum or candy (100-250 ppm). At the low concentrations used, neither the TiO food additives nor control TiO NPs had an impact on gas production and only a minor effect on fatty acids profiles (C16:00, C18:00, 15:1 w5c, 18:1 w9c and 18:1 w9c, p < 0.05). DNA profiles and phylogenetic distributions confirmed limited effects on the bacterial community, with a modest decrease in the relative abundance of the dominant Bacteroides ovatus in favor of Clostridium cocleatum (-13% and +14% respectively, p < 0.05). Such minor shifts in the treated consortia suggest that food grade and nano-TiO particles do not have a major effect on human gut microbiota when tested in vitro at relevant low concentrations. However, the cumulative effects of chronic TiO NP ingestion remain to be tested.
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http://dx.doi.org/10.1016/j.fct.2017.05.050DOI Listing
August 2017

Criteria to define a more relevant reference sample of titanium dioxide in the context of food: a multiscale approach.

Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2017 May 14;34(5):653-665. Epub 2017 Feb 14.

a UR1268 BIA (Biopolymères Interactions Assemblages) , INRA , Nantes , France.

Titanium dioxide (TiO) is a transition metal oxide widely used as a white pigment in various applications, including food. Due to the classification of TiO nanoparticles by the International Agency for Research on Cancer as potentially harmful for humans by inhalation, the presence of nanoparticles in food products needed to be confirmed by a set of independent studies. Seven samples of food-grade TiO (E171) were extensively characterised for their size distribution, crystallinity and surface properties by the currently recommended methods. All investigated E171 samples contained a fraction of nanoparticles, however, below the threshold defining the labelling of nanomaterial. On the basis of these results and a statistical analysis, E171 food-grade TiO totally differs from the reference material P25, confirming the few published data on this kind of particle. Therefore, the reference material P25 does not appear to be the most suitable model to study the fate of food-grade TiO in the gastrointestinal tract. The criteria currently to obtain a representative food-grade sample of TiO are the following: (1) crystalline-phase anatase, (2) a powder with an isoelectric point very close to 4.1, (3) a fraction of nanoparticles comprised between 15% and 45%, and (4) a low specific surface area around 10 m g.
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http://dx.doi.org/10.1080/19440049.2017.1284346DOI Listing
May 2017
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