fumarates and diethyl-maleate

The Keap1-Nrf2 system plays a critical role in cellular defense against electrophiles and reactive oxygen species. Keap1 possesses a number of cysteine residues, some of which are highly reactive and serves as sensors for these insults. Indeed, point mutation of Cys151 abrogates the response to certain electrophiles. However, this mutation does not affect the other set of electrophiles, suggesting that multiple sensor systems reside within the cysteine residues of Keap1. The precise contribution of each reactive cysteine to the sensor function of Keap1 remains to be clarified. To elucidate the contribution of Cys151 in vivo, in this study we adopted transgenic complementation rescue assays. Embryonic fibroblasts and primary peritoneal macrophages were prepared from mice expressing the Keap1-C151S mutant. These cells were challenged with various Nrf2 inducers. We found that some of the inducers triggered only marginal responses in Keap1-C151S-expressing cells, while others evoked responses in a comparable magnitude to those observed in the wild-type cells. We found that tert-butyl hydroquinone, diethylmaleate, sulforaphane, and dimethylfumarate were Cys151 preferable, whereas 15-deoxy-Δ(12,14)-prostaglandin J(2) (15d-PG-J(2)), 2-cyano-3,12 dioxooleana-1,9 diene-28-imidazolide (CDDO-Im), ebselen, nitro-oleic acid, and cadmium chloride were Cys151 independent. Experiments with embryonic fibroblasts and primary macrophages yielded consistent results. Experiments testing protective effects against the cytotoxicity of 1-chloro-2,4-dinitrobenzene of sulforaphane and 15d-PG-J(2) in Keap1-C151S-expressing macrophages revealed that the former inducer was effective, while the latter was not. These results thus indicate that there exists distinct utilization of Keap1 cysteine residues by different chemicals that trigger the response of the Keap1-Nrf2 system, and further substantiate the notion that there are multiple sensing mechanisms within Keap1 cysteine residues.

Topics: Adaptor Proteins, Signal Transducing; Amino Acid Substitution; Animals; Antioxidants; Azoles; Cytoskeletal Proteins; Dimethyl Fumarate; Fumarates; Gene Expression; Gene Expression Regulation; Glutamate-Cysteine Ligase; HEK293 Cells; Humans; Hydroquinones; Imidazoles; Isoindoles; Isothiocyanates; Kelch-Like ECH-Associated Protein 1; Macrophages, Peritoneal; Maleates; Mice; Mice, Transgenic; NAD(P)H Dehydrogenase (Quinone); NF-E2-Related Factor 2; Oleanolic Acid; Organoselenium Compounds; Oxidants; Oxidative Stress; Sulfoxides; Transcriptional Activation

Chairs and sofas imported from China to Europe were shown to contain dimethyl fumarate (DMF), a sensitizing, volatile chemical. Many of the sensitized patients also had positive patch test reactions to acrylates.. To analyse the occurrence and strength of DMF sensitization and the appearance of concomitant reactions.. Patch testing with DMF in concentrations of 0.1-0.00001% was carried out in 37 patients. Diethyl fumarate (DEF), diethyl maleate (DEM), dimethyl maleate (DMM), ethyl acrylate (EA), methyl acrylate (MA), and methyl methacrylate (MMA) were also tested with a dilution series at equimolar concentrations.. The lowest concentration of DMF eliciting a reaction varied between 0.0001% and 0.1% and all but four patients reacted concurrently to DEF. DEM elicited positive patch test reactions in 21/37 patients and DMM reactions were seen in all 9 patients tested. EA elicited positive reactions in 13/37 patients and a positive MA reaction was seen in 7/37 patients, 2 of whom also reacted to MMA.. The strength of the sensitization to DMF showed variation and concurrent reactions were common. Concurrent reactions to (meth)acrylates were seen in patients, who reacted to lower (0.001% or less) DMF concentration probably elicited by cross-reactivity.

Topics: Acrylates; Adult; China; Dermatitis, Allergic Contact; Dimethyl Fumarate; Female; Finland; Fumarates; Humans; Interior Design and Furnishings; Male; Maleates; Methylmethacrylate; Middle Aged; Patch Tests; United Kingdom

The reactivity of various vinyl ethers and vinyloxy derivatives of ribose in the presence of diethyl fumarate or diethyl maleate was investigated for evaluating the potential of donor-acceptor-type copolymerization applied to unsaturated monomers derived from renewable feedstock. The photochemically induced polymerization of model monomer blends in the bulk state was monitored by infrared spectroscopy. The method allowed us to examine the influence of monomer pair structure on the kinetic profiles. The simultaneous consumption of both monomers was observed, supporting an alternating copolymerization mechanism. A lower reactivity of the blends containing maleates compared with fumarates was confirmed. The obtained kinetic data revealed a general correlation between the initial polymerization rate and the Hansen parameter δ(H) associated with the H-bonding aptitude of the donor monomer.

Topics: Free Radicals; Fumarates; Maleates; Polymerization; Polymers; Polyvinyl Chloride; Ribose; Spectroscopy, Fourier Transform Infrared; Ultraviolet Rays; Vinyl Compounds

The application of evolving window factor analysis (EFA), subwindow factor analysis (SFA), iterative target transformation factor analysis (ITTFA), alternating least squares (ALS), Gentle, automatic window factor analysis (AUTOWFA) and constrained key variable regression (CKVR) to resolve on-flow LC-NMR data of eight compounds into individual concentration and spectral profiles is described. CKVR has been reviewed critically and modifications are suggested to obtain improved results. A comparison is made between three single variable selection methods namely, orthogonal projection approach (OPA), simple-to-use interactive self-modelling mixture analysis approach (SIMPLISMA) and simplified Borgen method (SBM). It is demonstrated that LC-NMR data can be resolved if NMR peak cluster information is utilised.

Topics: Chromatography, Liquid; Factor Analysis, Statistical; Fumarates; Magnetic Resonance Spectroscopy; Maleates; Multivariate Analysis; Naphthols; Phenyl Ethers; Regression Analysis

A method is presented that allows for the convenient and reliable determination of (1)H-(1)H NMR coupling constants in higher order or symmetrically coupled spin systems. The method can be applied on any programmable FT-NMR spectrometer and is demonstrated here on micromole quantities of sample in a standard 5-mm NMR tube.

Topics: Fumarates; Magnetic Resonance Spectroscopy; Maleates; Microchemistry; Oleic Acid; Oleic Acids

Cellular thiols, and especially glutathione, act as scavenger nucleophiles and can protect against toxicity, mutagenicity, or transformation by ionizing radiation and many carcinogens. Development of a rapid assay to quantitate the cellular content of thiols could thus be useful in assessing or predicting cellular risk to damage. Several fluorescent thiol-reactive drugs, usually maleimide or bromobimane derivatives, have been described for use in histopathology. Most of these agents do not distinguish between protein and nonprotein thiols, and virtually all of these fluorescent stains have normally been used after fixation of the cells or tissues. We have found that some of the probes will, however, rapidly penetrate and bind within viable cells with little associated cytotoxicity; the amount bound can be easily quantified using flow cytometry. We have used several of these agents, in conjunction with fluorescence-activated cell sorting in V79 spheroids, to examine the thiol content of cells as a function of their depth or position in the spheroid. Additionally, the radiation response of cells from different depths has been assessed following addition of exogenous thiols including glutathione and WR-2721, or after treatment with thiol-depleting agents, including DL-buthionine-S,R-sulfoximine (BSO), diethylmaleate (DEM), and dimethylfumarate (DMF). Our studies indicate that examination of the thiol content and radiation response of the sorted cells provides an improved understanding of the modes of action of these compounds.

Topics: Animals; Buthionine Sulfoximine; Cell Survival; Cricetinae; Cricetulus; Flow Cytometry; Fumarates; Glutathione; Lung; Maleates; Methionine Sulfoximine; Oxygen; Radiation Tolerance; Staining and Labeling; Sulfhydryl Compounds; Sulfhydryl Reagents

Malondialdehyde (MDA) formation in mouse liver homogenates was measured in the presence of various glutathione depletors (5 mmol/l). After a lag phase of 90 min, the MDA formation increased from 1.25 nmol/mg protein to 14.5 nmol/mg in the presence of diethyl maleate (DEM), to 10.5 with diethyl fumarate (DEF) and to 4 with cyclohexenon by 150 min. It remained at 1.25 nmol/mg with phorone and in the control. On the other hand, glutathione (GSH) dropped from 55 nmol/mg to 50 nmol/mg in the control to, less than 1 with DEM, to 46 with DEF, to 3 with cyclohexenon and to 7 with phorone. The data show that the potency to deplete GSH is not related to MDA production in this system. DEM stimulated in vitro ethane evolution in a concentration-dependent manner and was strongly inhibited by SKF 525A. From type I binding spectra to microsomal pigments the following spectroscopic binding constants were determined: 2.5 mmol/l for phorone, 1.2 mmol/l for cyclohexenon, 0.5 mmol/l for DEM and 0.3 mmol/l for DEF. In isolated mouse liver microsomes NADPH-cytochrome P-450 reductase and NADH-cytochrome b5 reductase activity were unaffected by the presence of DEM, whereas ethoxycoumarin dealkylation was inhibited. Following in vivo pretreatment, hepatic microsomal electron flow as determined in vitro was augmented in the presence of depleting as well as non-depleting agents, accompanied by a shift from O2- to H2O2 production. It is concluded that it is not the absence of GSH which causes lipid peroxidation after chemically-induced GSH depletion but rather the interaction of the chemicals with the microsomal monoxygenase system.

Topics: 7-Alkoxycoumarin O-Dealkylase; Animals; Cyclohexanones; Cytochrome Reductases; Cytochrome-B(5) Reductase; Ethane; Fumarates; Glutathione; Ketones; Lipid Metabolism; Male; Maleates; Malondialdehyde; Mice; Microsomes, Liver; NADPH-Ferrihemoprotein Reductase; Oxygenases; Proadifen