Search results for "Epoxy Compounds"
showing 10 items of 77 documents
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…
Human liver cytosolic epoxide hydrolases.
1988
Human liver epoxide hydrolases were characterized by several criteria and a cytosolic cis-stilbene oxide hydrolase (cEHcso) was purified to apparent homogeneity. Styrene oxide and five phenylmethyloxiranes were tested as substrates for human liver epoxide hydrolases. With microsomes activity was highest with trans-2-methylstyrene oxide, followed by styrene 7, 8-oxide, cis-2-With methylstyrene oxide, cis-1,2-dimethylstyrene oxide, trans-1, 2-dimethylstyrene oxide and 2, 2-dimethylstyrene oxide. With cytosol the same order was obtained for the first three substrates, whereas activity with 2, 2-dimethylstyrene oxide was higher than with cis-1,2-dimethylstyrene oxide and no hydrolysis occurred …
Determination of haemoglobin adducts of acrylamide and glycidamide in smoking and non-smoking persons of the general population
2005
Acrylamide (AA) is a food-borne toxicant suspected to be carcinogenic to humans. It is formed in the heating process of starch-containing food. Currently, there is a great discussion about the possible human health risks connected with the dietary uptake of acrylamide. Haemoglobin adducts of acrylamide and its oxidative metabolite glycidamide are both markers of biochemical effect. However, because glycidamide has a higher carcinogenic potency than acrylamide itself, the glycidamide adduct might mirror the genotoxicity better than acrylamide adducts. In order to gain more information about the human metabolism of acrylamide, we investigated a small group of persons for the effective interna…
Design, Synthesis, and Biological Evaluation of Novel Fluorinated Ethanolamines
2011
The preparation of novel fluorinated allylamines and their use as key fragments for the stereoselective synthesis of hydroxyethyl secondary amine (HEA)-type peptidomimetics is described. Our strategy employs chiral sulfinyl imines as synthesis intermediates, by treatment of hemiaminal precursors with two equivalents of vinylmagnesium bromide. The subsequent oxidation of the allylic amines to the corresponding epoxides was achieved by treatment with methyl(trifluoromethyl)dioxirane. Finally, epoxide ring opening with a range of nitrogen nucleophiles provided a library of HEA-derived peptidomimetics with a phenyldifluoromethylene moiety. The biological evaluation of these derivatives revealed…
Analytical strategies for organic food packaging contaminants
2016
In this review, we present current approaches in the analysis of food-packaging contaminants. Gas and liquid chromatography coupled to mass spectrometry detection have been widely used in the analysis of some relevant families of these compounds such as primary aromatic amines, bisphenol A, bisphenol A diglycidyl ether and related compounds, UV-ink photoinitiators, perfluorinated compounds, phthalates and non-intentionally added substances. Main applications for sample treatment and different types of food-contact material migration studies have been also discussed. Pressurized Liquid Extraction, Solid-Phase Microextraction, Focused Ultrasound Solid-Liquid Extraction and Quechers have been …
Amorphous Calcium Phosphates: Solvent-Controlled Growth and Stabilization through the Epoxide Route.
2020
Calcium phosphates stand among the most promising nanobiomaterials in key biomedical applications, such as bone repairment, signalling or drug/gene delivery. Their intrinsic properties as crystalline structure, composition, particle shape and size define their successful use. Among these compounds, metastable amorphous calcium phosphate (ACP) is currently gaining particular attention due to its inherently high reactivity in solution, which is crucial in bone development mechanisms. However, the preparation of this highly desired (bio)material with control over its shape, size and phase purity remains as a synthetic challenge. In this work, the epoxide route was adapted for the synthesis of …
The in vitro metabolic activation of dibenz[a,h]anthracene, catalyzed by by rat liver microsomes and examined by 32P-postlabelling.
1991
DNA has been incubated in vitro with dibenz[a,h]anthracene (DB[a,H]A) and the related 5,6-diol and 3,4-diol in the presence of 3-methylcholanthrene- or Aroclor 1254-induced rat liver microsomes. After incubation, the DNA was extracted and examined for the presence of aromatic adducts using the nuclease P1 modification of the 32P-postlabelling technique. The maps of PEI-cellulose plates and autoradiography showed that 92% of the radioactivity contained in DB[a,h]A-DNA adduct spots is derived from the related 3,4-diol and that about 50% of the adducts may be formed following the conversion of this diol to the bay-region anti- and syn-3,4-diol 1,2-oxides.
Detoxification of optically active bay- and fjord-region polycyclic aromatic hydrocarbon dihydrodiol epoxides by human glutathione transferase P1-1 e…
1998
Dihydrodiol epoxides (DEs) are important carcinogenic metabolites of polycyclic aromatic hydrocarbons (PAHs). The metabolic formation of four stereoisomeric DEs (a pair of optically active diastereomers termed as syn- and anti-form) is possible. Glutathione tranferases (GSTs) have been demonstrated to catalyze the detoxification of DEs. Purified GSTs display remarkable differences in catalytic efficiencies towards bay- and fjord-region DEs along with a high degree of regio- and stereoselectivity. Here we determined to which extent heterologously expressed human GSTP1-1, a major GST isoform in lung, affects the mutagenicity of stereoisomeric bay-region DEs of benzo[a]pyrene in Chinese hamste…
Catechol-Initiated Polyethers: Multifunctional Hydrophilic Ligands for PEGylation and Functionalization of Metal Oxide Nanoparticles
2012
Bifunctional CA-PEG (catechol-poly(ethylene glycol)) and multifunctional CA-PEG-PGA/PEVGE (poly(glycidyl amine)/poly(ethylene glycol vinyl glycidyl ether)) ligands for the functionalization and solubilization of nanoparticles are introduced. Tunable polymers with polydispersities1.25 and molecular weights in the range 500-7700 g mol(-1) containing a catechol moiety for conjugation to metal oxide nanoparticles were prepared. The functional PEG ligands were synthesized starting from the acetonide-protected catechol initiator 2,2-dimethyl-1,3-benzodioxole-5-propanol (CA-OH) for oxyanionic polymerization. CA-OH was used both for homopolymerization of ethylene oxide (EO) as well as copolymerizat…
Autocatalytic cleavage of Clostridium difficile toxin B.
2007
Clostridium difficile, the causative agent of nosocomial antibiotic-associated diarrhoea and pseudomembranous colitis, possesses two main virulence factors: the large clostridial cytotoxins A and B. It has been proposed that toxin B is cleaved by a cytosolic factor of the eukaryotic target cell during its cellular uptake. Here we report that cleavage of not only toxin B, but also all other large clostridial cytotoxins, is an autocatalytic process dependent on host cytosolic inositolphosphate cofactors. A covalent inhibitor of aspartate proteases, 1,2-epoxy-3-(p-nitrophenoxy)propane, completely blocked toxin B function on cultured cells and was used to identify its catalytically active prote…