References of "Sergent, Thérèse"
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See detailCharacterization of Black locust (Robinia pseudoacacia L.) heartwood extractives: identification of resveratrol and piceatannol
Sergent, Thérèse; Kohnen, Stéphane; Jourez, Benoît ULg et al

in Wood Science and technology (2014)

Robinia pseudoacacia L. heartwood is characterized by a very high natural durability. However, a significant difference was observed between the mature and juvenile heartwood, the latter presenting less ... [more ▼]

Robinia pseudoacacia L. heartwood is characterized by a very high natural durability. However, a significant difference was observed between the mature and juvenile heartwood, the latter presenting less durability against fungi decay, which could be attributed to lower extractive content. In order to elucidate this idea, extractives from mature and juvenile heartwoods of black locust trees were investigated. Results showed that extractive and phenolic contents were higher in mature than in juvenile heartwoods. The identification of phenolic compounds by UPLC–DAD–MS/MS revealed, for the first time, the presence of resveratrol and piceatannol. These two stilbenes as well as the flavonoid dihydrorobinetin were present at the highest level in mature heartwood, and as they are known antifungals, they could account for the great durability of mature heartwood. The stilbenes were detected in significant amounts particularly in mature heartwood where piceatannol reached a level tenfold higher than that reported for Japanese knotweed roots, the primary natural source of these stilbenes, whereas resveratrol level was comparable with reported values. As resveratrol and piceatannol receive increasing demand for nutraceutical, cosmetic and, possibly, pharmaceutical purposes, due to their beneficial health effects, this study underlines the use of R. pseudoacacia as a promising sustainable and economical source of resveratrol and piceatannol. [less ▲]

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See detailCYP1A1 and CYP3A4 modulation by dietary flavonoids in human intestinal Caco-2 cells.
Sergent, Thérèse; Dupont, Isabelle; Van Der Heiden, Edwige ULg et al

in Toxicology Letters (2009), 191

Flavonoids have been proposed to exert beneficial effects in a multitude of disease states. However, evidence of potential toxic actions has also emerged. Since large doses of flavonoids can be ... [more ▼]

Flavonoids have been proposed to exert beneficial effects in a multitude of disease states. However, evidence of potential toxic actions has also emerged. Since large doses of flavonoids can be encountered in the intestine simultaneously with ingested drugs and pollutants, this study aimed at investigating nine individual flavonoid compounds and their interactions with the major intestinal isoforms of cytochrome P450, i.e. CYPs 1A1 and 3A4, using human intestinal Caco-2 cells cultivated in a serum-free medium. Genistein, quercetin and chrysin provoked a dose-dependent inducing effect on the CYP1A1 activity, measured with the EROD assay. However, they did not affect the CYP1A1 mRNA expression, suggesting they are not aryl hydrocarbon receptor-ligands in intestinal cells and act at a post-transcriptional level. Chrysin, at 50muM, was detected as a potent inhibitor of the TCDD-induced CYP1A1 activity, leading the activity to ca. 10% of the TCDD-control value (n=3), this effect involving, at least partly, direct interactions at the enzyme level. Quercetin was also shown to significantly inhibit the constitutive CYP3A4 activity, measured by the 6beta-(OH)-testosterone assay, and to impair its induction by 1,25-vitamin D(3). Chrysin, quercetin and genistein, were detected as significant inhibitors of the 1,25-vitamin D(3)-induced CYP3A4 activity. In vivo, these effects could result in reduced activation of procarcinogens and/or in drug bioavailability limitation. They underline the importance of intestinal studies to assess food safety and health risks linked to the ingestion of flavonoid-enriched supplements or functional foods. [less ▲]

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See detailCYP1A1 induction and CYP3A4 inhibition by the fungicide imazalil in the human intestinal Caco-2 cells-Comparison with other conazole pesticides
Sergent, Thérèse; Dupont, Isabelle; Jassogne, Coralie et al

in Toxicology Letters (2009), 184(3), 159-168

Imazalil (IMA) is a widely used imidazole-antifungal pesticide and. therefore. a food contaminant. This compound is also used as a drug (enilconazole). As intestine is the first site of exposure to ... [more ▼]

Imazalil (IMA) is a widely used imidazole-antifungal pesticide and. therefore. a food contaminant. This compound is also used as a drug (enilconazole). As intestine is the first site of exposure to ingested drugs and pollutants, we have investigated the effects of IMA, at realistic intestinal concentrations, on xenobiotic-metabolizing enzymes and efflux pumps by using Caco-2 cells, as a validated in vitro model of the human intestinal absorptive epithelium. For comparison, other conazole fungicides, i.e. ketoconazole, propiconazole and tebuconazole. were also studied. IMA induced cytochrome P450 (CYP) 1A1 activity to the same extent as benzo(a)pyrene (B(a)P) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), in a dose-and time-dependent manner. Cell-free aryl hydrocarbon receptor (AhR) binding assay and reporter gene assay suggested that IMA is not an AhR-ligand, implying that IMA-mediated induction should involve an AhR-independent pathway. Moreover, IMA strongly inhibited the CYP3A4 activity in 1,25-vitamin D-3-induced Caco-2 cells. The other fungicides had weak or nil effects on CYP activities. Study of the apical efflux pump activities revealed that ketoconazole inhibited both P-glycoprotein (Pgp) and multidrug resistance-associated protein 2 (MRP-2) or breast cancer resistance protein (BCRP), whereas IMA and other fungicides did not. Our results imply that coingestion of IMA-contaminated food and CYP3A4- or CYP1A1-metabolizable drugs or chemicals could lead to drug bioavailability modulation or toxicological interactions, with possible adverse effects for human health. (C) 2008 Elsevier Ireland Ltd. All rights reserved. [less ▲]

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See detailFood flavonoid aryl hydrocarbon receptor-mediated agonistic/antagonistic/synergic activities in human and rat reporter gene assays
Van Der Heiden, Edwige ULg; Bechoux, Nathalie ULg; Muller, Marc ULg et al

in Analytica Chimica Acta (2009), 637

Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor mediating the adverse effects of dioxins and polycyclic aromatic hydrocarbons (PAHs). In this study, we investigated the genetic ... [more ▼]

Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor mediating the adverse effects of dioxins and polycyclic aromatic hydrocarbons (PAHs). In this study, we investigated the genetic-, time-, dose-, species- and tissue-dependent AhR-mediated agonistic/ antagonistic activities of three food flavonoids: quercetin, chrysin and genistein. To that end, four stably transfected cell lines were used in cell-based luciferase reporter gene assays: three lines were transformed with the ptKLuc vector harbouring four dioxinresponsive elements (DREs) upstream of the thymidine kinase promoter and the luciferase gene (HepG2-Luc, T-47D-Luc and H4IIE-ULg). The fourth is a patented cell line transformed with a different construct: H4IIE DR-CALUX®. Both H4IIE cells were compared for their genetic construction. Human hepatoma (HepG2-Luc) and human breast tumour (T-47D-Luc) cells were compared for tissue-dependent effects. Rat hepatoma (H4IIE-ULg) and human hepatoma (HepG2-Luc) cellswere compared for species-dependent activities.We concluded that quercetin, chrysin and genistein act in a time-, dose-, species- and tissue-specific way. For example, genistein displayed agonistic activities when exposed to rat hepatoma cells during 6h but not after 24 h. Flavonoids displayed agonistic/antagonistic activities in human breast tumour cells, depending on the exposure time, while in human hepatoma cells, only antagonistic activities of flavonoids were measured. In addition, we report, in all the cells, a synergy between an isoflavone and two food contaminants; the 2,3,7,8-tetrachlorodibenzop- dioxin and 3-methylcholanthrene, a PAH. In rat cells, this synergy occurred when cells were exposed to flavonoids and contaminant for 6h, while it was observed in human cells only after 24 h. [less ▲]

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See detailTime-, species- and tissue-dependent activity profiles of food flavonoids on the activation of the aryl hydrocarbon pathway
Van Der Heiden, Edwige ULg; Bechoux, Nathalie ULg; Sergent, Thérèse et al

in van Ginkel, L. A.; Bergwerff, A. A. (Eds.) Residues of Veterinary Drugs in Foods, Proceedings of the Euroresidue VI Conference (2008, May 19)

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See detailImazalil modulates CYPs 1A1 and 3A4 activities in the human Caco-2 cells as an intestinal model to assess food safety
Sergent, Thérèse; Ribonnet, Laurence; Jassogne, C. et al

in Toxicology Letters (2007), 172

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See detailNew experimental approach of identification and characterization of emerging risks in food safety (EMRISK).
Ribonnet, Laurence; Sergent, Thérèse; Nobels, Ingrid et al

Report (2007)

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See detailStudy of the flavonoids effect on the AhR-dependent transcription using reporter gene assays
Van Der Heiden, Edwige ULg; Bechoux, Nathalie ULg; Sergent, Thérèse et al

in Journal of Biotechnology (2007), 131(2, Suppl. S), 6

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See detailSet up of an experimental tool in order to investigate food chemical contaminant toxicity at realistic concentrations
Ribonnet, Laurence; Sergent, Thérèse; Nobels, Ingrid et al

in Toxicology Letters (2007), 172

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