Search results for "xenobiotic"
showing 10 items of 127 documents
Hepatocyte cell lines: their use, scope and limitations in drug metabolism studies.
2006
Gaining knowledge on the metabolism of a drug, the enzymes involved and its inhibition or induction potential is a necessary step in pharmaceutical development of new compounds. Primary human hepatocytes are considered a cellular model of reference, as they express the majority of drug-metabolising enzymes, respond to enzyme inducers and are capable of generating in vitro a metabolic profile similar to what is found in vivo. However, hepatocytes show phenotypic instability and have a restricted accessibility. Different alternatives have been explored in the past recent years to overcome the limitations of primary hepatocytes. These include immortalisation of adult or fetal human hepatic cel…
Multixenobiotic resistance efflux activity in Daphnia magna and Lumbriculus variegatus
2015
Multixenobiotic resistance is a phenomenon in which ATP-binding cassette (ABC) family proteins transfer harmful compounds out of cells. Daphnia magna and Lumbriculus variegatus are model species in aquatic ecotoxicology, but the presence and activity of ABC proteins have not been well described in these species. The aim of this work was to study the presence, activity, and inhibition of ABC transport proteins in D. magna and L. variegatus. The presence of abcb1 and abcc transcripts in 8–9-day-old D. magna was investigated by qRT-PCR. The activity of MXR in D. magna and L. variegatus was explored by influx of the fluorescent ABC protein substrates rhodamine B and calcein-AM, with and without…
Oral enzymatic detoxification system: Insights obtained from proteome analysis to understand its potential impact on aroma metabolization
2021
The oral cavity is an entry path into the body, enabling the intake of nutrients but also leading to the ingestion of harmful substances. Thus, saliva and oral tissues contain enzyme systems that enable the early neutralization of xenobiotics as soon as they enter the body. Based on recently published oral proteomic data from several research groups, this review identifies and compiles the primary detoxification enzymes (also known as xenobiotic-metabolizing enzymes) present in saliva and the oral epithelium. The functions and the metabolic activity of these enzymes are presented. Then, the activity of these enzymes in saliva, which is an extracellular fluid, is discussed with regard to the…
Bis(hydroxyphenyl)methane-bisphenol F-metabolism by the HepG2 human hepatoma cell line and cryopreserved human hepatocytes
2011
author cannot archive publisher's version/PDF; International audience; Bisphenol F (BPF) is present in the environment and as a contaminant of food. Humans may, therefore, be exposed to BPF, and an assessment of this risk is required. BPF has been shown to have genotoxic and endocrine-disruptor properties in a human hepatoma cell line (HepG2), which is a model system for studies of xenobiotic toxicity. In this study, we investigated the ability of HepG2 cells to biotransform BPF, because metabolism may affect the observed effects of BPF, and we compared this metabolic capacity with that of human hepatocytes. Cells were incubated for 24 hours with [(3)H]-BPF. The culture medium was then conc…
Effets des polyphénols de vin rouge sur la prolifération cellulaire et sur le métabolisme du resvératrol
2011
It is known that moderate consumption of red wine may protect against many diseases, in particular because of its polyphenols. We studied in particular the effect of these polyphenols on colorectal cancer, one of the most common cancers in industrialized countries. Some purified polyphenols from red wine, like resveratrol and quercetin, showed antiproliferative effects against colorectal cancer cells.Our first approach was to use polyphenolic extracts from Burgundy red wine. We then studied their in vitro effects on human colorectal tumor cell lines SW480’s proliferation and the interactions between the polyphenols and the transport and metabolism of resveratrol; and secondly, the effects o…
Prospects of in vivo 31P NMR method in glyphosate degradation studies in whole cell system
2009
Abstract The degradation of the phosphonate herbicide glyphosate ( N -phosphonomethylglycine) by four taxonomically distinct microorganisms was studied in vivo in whole cell system using phosphorus nuclear magnetic spectroscopy ( 31 P NMR). The time-course of glyphosate metabolization in dense cell cultures was followed by means of 31 P NMR up to 21 days after the addition. The results obtained by this non-invasive way confirmed that the cells of Spirulina platensis and Streptomyces lusitanus biodegrade herbicide. Moreover, phosphorus starvation influenced the rate of glyphosate degradation by S. platensis . On the other hand, the results of similar measurements in the cultures of green alg…
On the Ability of Perfluorohexane Sulfonate (PFHxS) Bioaccumulation by Two
2019
PFASs (perfluoroalkyl and polyfluoroalkyl substances) are highly fluorinated, aliphatic, synthetic compounds with high thermal and chemical stability as well as unique amphiphilic properties which make them ingredients in a range of industrial processes. PFASs have attracted consideration due to their persistence, toxicity and bioaccumulation tendency in the environment. Recently, attention has begun to be addressed to shorter-chain PFASs, such as perfluorohexane sulfonate [PFHxS], apparently less toxic to and more easily eliminated from lab animals. However, short-chain PFASs represent end-products from the transformation of fluorotelomers whose biotic breakdown reactions have not been ide…
Analytical Methods Used in Biotransformation Studies of Organophosphonates
2022
This work was supported by the National Science Centre, Poland (NCN) grant number 2017/27/B/NZ4/00698. Among diverse organophosphorus compounds, whose residues are determined in various ecosystems, phosphonates possess special meaning. Regarding their biological activity, capability to chelating metal cations, and stability of direct carbon to phosphorus bond under physiological conditions, phosphonic compounds found many various applications. These compounds are commonly used as pesticides, drugs, anticorrosive agents, and additives to surfactants. Common use of these substances results in an increase in their concentration in various ecosystems which may cause considerable ecological prob…
Cell Systems for Use in Studies on the Relationship Between Foreign Compound Metabolism and Toxicity
1995
: Since the metabolism of most foreign compounds is predominantly controlled by hepatic in metabolism, isolated hepatocytes in most cases quite well predict the pattern of the overall metabolism of a given compound. Methods have been developed for cryopreserving isolated hepatocytes from man and other species with satisfactory maintenance of foreign compound metabolizing enzyme activities. The installation of a bank of cryopreserved hepatocytes from different species is possible and may be used for rational species extrapolation. It is necessary for some toxicological investigations to have hepatocytes which retain their differentiated status in culture for a sufficient time period. This mi…
Toxicological implications of enzymatic control of reactive metabolites.
1990
Many foreign compounds are transformed into reactive metabolites, which may produce genotoxic effects by chemically altering critical biomolecules. Reactive metabolites are under the control of activating, inactivating and precursor sequestering enzymes. Such enzymes are under the long-term control of induction and repression, as well as the short-term control of post-translational modification and low molecular weight activators or inhibitors. In addition, the efficiency of these enzyme systems in preventing reactive metabolite-mediated toxicity is directed by their subcellular compartmentalization and isoenzymic multiplicity. Extrapolation from toxicological test systems to the human req…