Search results for "biotransformation"
showing 10 items of 183 documents
Bioconcentration, biotransformation and elimination of pyrene in the arctic crustacean Gammarus setosus (Amphipoda) at two temperatures
2015
The influence of temperature on the bioaccumulation, toxicokinetics, biotransformation and depuration of pyrene was studied in the arctic marine amphipod Gammarus setosus. A two-compartment model was used to fit experimental values of total body burden, total metabolites and parent pyrene concentrations and to calculate toxicokinetic variables derived for two experimental treatments (2 and 8 °C). No statistically significant differences were observed with temperature for these toxicokinetic variables or bioconcentration factors. Contrarily, the Q10 values suggested that the toxicokinetic variables ke and km were temperature-dependent. This may be explained by the high standard deviation of …
Bioconversion of amino acids into flavouring alcohols and esters by Erwinia carotovora subsp. atroseptica
1991
International audience; Erwinia carotovora subsp. atroseptica produced flavour compounds when infecting endives (Cichorium intybus). These compounds were identified as esters and branched-chain alcohols.They were produced from amino acids and some of them such as methionol, methionol acetate, isobutanol, isobutyl acetate, beta-phenyl ethanol and tryptophol were produced with good yields.
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…
Metabolic activation to a mutagen of 3-hydroxy-trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene, a secondary metabolite of benzo[a]pyrene
1987
3-Hydroxy-trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene (3-OH-BP-7,8-diol) was isolated from arylsulfatase/beta-glucuronidase-treated bile of rats to which 3-hydroxybenzo[a]pyrene (3-OH-BP) has been administered. This triol was investigated for mutagenicity in Salmonella typhimurium (reversion to histidine prototrophy of strains TA 97, TA 98, TA 100 and TA 1537) and in V79 Chinese hamster cells (acquisition of resistance to 6-thioguanine). When no exogenous metabolizing system was added the triol was inactive, while 3-OH-BP showed weak mutagenic effects with all four bacterial strains. In the presence of NADPH-fortified postmitochondrial supernatant fraction (S9 mix) of liver homogenate fro…
Soil mutagens are airborne mutagens: variation of mutagenic activities induced in Salmonella typhimurium TA 98 and TA 100 by organic extracts of agri…
2000
As our hypothesis was that soil mutagens are airborne mutagens, possibly modified by soil microorganisms, we checked solvent extracts from agricultural and forest soils collected during late summer in the environment of Mainz, a region highly charged by anthropogenic air pollution, or near Bayreuth, a rural low charged region of Germany, or in a remote region of western Corsica without anthropogenic air pollution for the presence of mutagenicity in Salmonella typhimurium. Levels of mutagenic activities were quantified by calculation of revertants/g from the initial slope of dose-response curves applying tester strains S. typhimurium TA 98 and TA 100 in the absence and presence of an activat…
Drug biotransformation by human hepatocytes. In vitro/in vivo metabolism by cells from the same donor.
2001
Abstract Background/Aims : Cultured human hepatocytes are considered a close model to human liver. However, the fact that hepatocytes are placed in a microenvironment that differs from that of the cell in the liver raises the question: to what extent does drug metabolism in vitro reflect that of the liver in vivo? This issue was examined by investigating the in vitro and in vivo metabolism of aceclofenac, an analgesic/anti-inflammatory drug. Methods : Hepatocytes isolated from programmed liver biopsies were incubated with aceclofenac, and the metabolites formed were investigated by HPLC. During the course of clinical recovery, patients were given the drug, and the metabolites, largely prese…
Microsomal Biotransformation of Benzo[ghi]perylene, a Mutagenic Polycyclic Aromatic Hydrocarbon without a “Classic” Bay Region
2005
Carcinogenic polycyclic aromatic hydrocarbons (PAH), e.g., benzo[a]pyrene (BaP), possess a bay region comprising an ortho-fused benzene ring. Benzo[ghi]perylene (BghiP) represents the group of PAHs lacking such a "classic" bay region and hence cannot be metabolically converted like BaP to bay region dihydrodiol epoxides considered as ultimate mutagenic and carcinogenic metabolites of PAH. BghiP exhibits bacterial mutagenicity in strains TA98 (1.3 his(+)-revertant colonies/nmol) and TA100 (4.3 his(+)-revertant colonies/nmol) of Salmonella typhimurium after metabolic activation by the postmitochondrial hepatic fraction of CD rats treated with 3-methylcholanthrene. Inhibition of microsomal epo…
Involvement of acyl coenzyme A oxidase isozymes in biotransformation of methyl ricinoleate into gamma-decalactone by Yarrowia lipolytica.
2000
ABSTRACT We reported previously on the function of acyl coenzyme A (acyl-CoA) oxidase isozymes in the yeast Yarrowia lipolytica by investigating strains disrupted in one or several acyl-CoA oxidase-encoding genes ( POX1 through POX5 ) (H. Wang et al., J. Bacteriol. 181:5140–5148, 1999). Here, these mutants were studied for lactone production. Monodisrupted strains produced similar levels of lactone as the wild-type strain (50 mg/liter) except for Δ pox3 , which produced 220 mg of γ-decalactone per liter after 24 h. The Δ pox2 Δpox3 double-disrupted strain, although slightly affected in growth, produced about 150 mg of lactone per liter, indicating that Aox2p was not essential for the biotra…
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…
Hepatocytes--the choice to investigate drug metabolism and toxicity in man: in vitro variability as a reflection of in vivo.
2007
The pharmaceutical industry is committed to marketing safer drugs with fewer side effects, predictable pharmacokinetic properties and quantifiable drug-drug interactions. Drug metabolism is a major determinant of drug clearance and interindividual pharmacokinetic differences, and an indirect determinant of the clinical efficacy and toxicity of drugs. Progressive advances in the knowledge of metabolic routes and enzymes responsible for drug biotransformation have contributed to understanding the great metabolic variations existing in human beings. Phenotypic as well genotypic differences in the expression of the enzymes involved in drug metabolism are the main causes of this variability. How…