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1.
Food Chem ; 350: 129222, 2021 Jul 15.
Article in English | MEDLINE | ID: mdl-33607411

ABSTRACT

The reaction pathways were investigated by which a fungoid chitosan (CsG) may protect against photooxidative decay of model solutions and a sulphite-free white wine. Samples containing CsG were dark incubated for 2 days before exposure to fluorescent lighting for up to 21 days in the presence of wine like (+)-catechin and/or iron doses. In both systems CsG at winemaking doses significantly reduced the photoproduction of acetaldehyde and, to a better extent, glyoxylic acid, two key reactive aldehydes implicated in wine oxidative spoilage. After 21 days, CsG was two-fold more effective than sulphur dioxide in preventing glyoxylic acid formation and minimizing the browning of white wine. Among the antioxidant mechanisms involved in CsG protective effect, iron chelation, and hydrogen peroxide quenching were demonstrated. Besides, the previously unreported tartrate displacement from the [iron(III)-tartrate] complex was revealed as an additional inhibitory mechanism of CsG under photo-Fenton oxidation conditions.


Subject(s)
Aldehydes/chemistry , Chitosan/chemistry , Photochemical Processes , Wine/analysis , Antioxidants/chemistry , Catechin/chemistry , Glyoxylates/chemistry , Oxidation-Reduction , Sulfur Dioxide/chemistry , Tartrates/chemistry
2.
Food Chem ; 285: 67-76, 2019 Jul 01.
Article in English | MEDLINE | ID: mdl-30797377

ABSTRACT

The efficacy against oxidative degradation in model and sulphite-free white wines of two commercial, insoluble chitosans (one being approved for winemaking) were investigated by electron paramagnetic resonance (EPR). Both compounds at various doses significantly inhibited the formation of α-(4-pyridyl-1-oxide)-N-t-butylnitrone (4-POBN)-1-hydroxyethyl adducts under normal wine storage conditions. Pre-incubation with 2 g/L chitosan followed by filtration had a better effect than adding 50 mg/L sulphur dioxide to the experimental Chardonnay wine on the release of 4-POBN adducts after 6 days of incubation with 100 µM iron(II). In a relevant photooxidative system acetaldehyde formation was significantly reduced after 6 days of incubation. Parallel EPR tests were performed to assess the importance of metal chelation (iron and copper) versus direct scavenging of hydroxyl radicals on the effect of chitosan. The present data support the potentiality of using biocompatible chitosan as a healthier complement and/or alternative to sulphur dioxide against white wine oxidative spoilage.


Subject(s)
Antioxidants/chemistry , Chitosan/chemistry , Sulfites/chemistry , Chelating Agents/chemistry , Electron Spin Resonance Spectroscopy , Ferrous Compounds/chemistry , Hydroxyl Radical/chemistry , Pyridines/chemistry , Spin Labels , Wine/analysis
3.
J Food Sci ; 83(11): 2858-2865, 2018 Nov.
Article in English | MEDLINE | ID: mdl-30289967

ABSTRACT

Many studies have shown that flavan-3-ols inhibit mammalian alpha-amylases but the published IC50 and Ki values vary up to a thousand times. We therefore tested the effects of 6 pure flavan-3-ols-abundant in green tea-on the activity of pure porcine pancreatic alpha-amylase (PPA) under steady-state kinetic conditions. We used both amylose and maltopentaose as substrates, along with spectrophotometry and chromatography as analytical tools, respectively. A Docking approach was also used to probe the interaction between PPA and each flavan-3-ol. The results showed that the 6 flavan-3-ols inhibit amylose hydrolysis with Ki comprised between 7 and 34 µM, according to a mixed inhibition profile for gallocatechin gallate, and a competitive inhibition profile for the 5 other flavanols. Only the galloyl-containing flavan-3-ols inhibited the maltopentaose hydrolysis with a Ki of about 30 µM according to a noncompetitive profile. We conclude that dietary flavan-3-ols could inhibit starch digestion nonnegligibly. The results of the docking trials were concordant with the kinetic data and have noticeably revealed that the cis-flavan-3-ols epigallocatechin gallate and epicatechin gallate bind similarly to PPA, involving π-stacking with Trp59.


Subject(s)
Flavonoids/pharmacology , Starch/metabolism , Tea/chemistry , alpha-Amylases/metabolism , Amylose/metabolism , Animals , Catechin/analogs & derivatives , Catechin/pharmacology , Digestion , Hydrolysis , Inhibitory Concentration 50 , Models, Molecular , Oligosaccharides/metabolism , Swine , alpha-Amylases/antagonists & inhibitors
4.
Eur J Med Chem ; 148: 306-313, 2018 Mar 25.
Article in English | MEDLINE | ID: mdl-29471119

ABSTRACT

A novel series of enediynes possessing pentafluorophenylsulfoxide have been developed. The innovative compounds possess antiproliferative activity against a broad panel of human cancer cells originating from breast, blood, lung, kidney, colon, prostate, pancreas or skin with IC50 ranging from 0.6 to 3.4 µM. The antiproliferative activity of enediynes in darkness is associated to their ability to compromise microtubule network. In addition, exposure to UV leads to double-stranded DNA cleavage caused by the newly synthesized molecules reducing further their IC50 in nanomolar range against human tumor cells, including chemo-resistant pancreatic cancer cells. Taken together, the examined data demonstrate that enediynes possessing pentafluorosulfoxide are promising molecules in the cancer therapy.


Subject(s)
Antineoplastic Agents/chemistry , Enediynes/chemistry , Sulfoxides/chemistry , Cell Line, Tumor , DNA/drug effects , DNA Breaks, Double-Stranded/drug effects , DNA Breaks, Double-Stranded/radiation effects , Humans , Microtubules/drug effects , Ultraviolet Rays
5.
J Ethnopharmacol ; 207: 251-267, 2017 Jul 31.
Article in English | MEDLINE | ID: mdl-28669771

ABSTRACT

ETHNOPHARMACOLOGICAL RELEVANCE: According to Saharian traditional medicine, Anvillea radiata Coss. & Dur. (Asteraceae) has been valued for treating a variety of ailments such as gastro-intestinal, liver and pulmonary diseases, and has gained awareness for its beneficial effect on postprandial hyperglycemia. However, to best of our knowledge, no detailed study of the antidiabetic curative effects of this plant has been conducted yet. AIM OF THE STUDY: To determine the hypoglycemic and antidiabetic effect of dietary supplementation with Anvillea radiata extracts on high-fat-diet (HFD)-induced obesity and insulin resistance in C57BL/6J mice in relation with antioxidant, anti-inflammatory, pancreatic beta-cells and skeletal muscle protection, and digestive enzyme inhibiting properties. MATERIALS AND METHODS: Six extracts (water soluble and organic) from aerial parts of the plant were analyzed phytochemically (total phenolic and flavonoid content) and screened for in vitro superoxide (by chemiluminescence) and hydroxyl radical (by electron paramagnetic resonance spin-trapping) scavenging, antioxidant (DPPH, TRAP and ORAC assays), xanthine oxidase, metal chelating, α-amylase and α-glucosidase inhibitory property, and protective effects on copper-induced lipoprotein oxidation. Then selected hydroalcoholic and aqueous extracts were assessed for toxicity in normal human lung fibroblasts and A549 cancer cells using FMCA and MTT assays. Two water-soluble extracts having the best overall properties were assessed for their (i) protective effect at 1-15µg/mL on metabolic activity of rat insulinoma-derived INS-1 cells exposed to hyperglycemic medium, and (ii) acute hypoglycemic effect on 16-weeks HFD-induced diabetic mice. Then diabetic mice were administered HFD supplemented by extracts (up to 150mg/kg/day) for 12 additional weeks using standard diet as control and the antidiabetic drug, metformin (150mg/kg), as positive control. Then the antidiabetic, anti-inflammatory and antioxidant activity of extracts were determined. RESULTS: Of the highly efficient polyphenolics-enriched hydroalcoholic and ethyl acetate extracts, the lyophilized aqueous (AQL) and butanol extracts were not toxic in cells (≤ 400µg/mL) or when given orally in normal mice (≤ 2000mg/kg), exerted a dose-dependent hypoglycemic action in diabetic mice, which was maximal at the dose of 150mg/kg. Upon administering this dose for 12 weeks, both extracts significantly ameliorated body weight control capacity, recovery of plasma glucose and insulin level, reduced oxidative stress in blood, myocardial and skeletal muscles, and improved hyperlipidemic and inflammatory status. Moreover, diabetes-related complications were optimally ameliorated by oral therapy based on halved doses (75mg/kg) of a mixture of AQL and metformin. CONCLUSIONS: Current investigation supports the traditional medicinal usage of Anvillea radiata and suggests that both readily accessible and low-cost bio-extracts have the potency to develop an antihyperglycemic, antihyperlipidemic and protective agent against beta-cells and muscle dysfunction at doses compatible with the common practices of indigenous people for the management of metabolic disorders.


Subject(s)
Anti-Inflammatory Agents/pharmacology , Antioxidants/pharmacology , Asteraceae/chemistry , Hypoglycemic Agents/pharmacology , Plant Extracts/pharmacology , 1-Butanol/chemistry , Animals , Anti-Inflammatory Agents/administration & dosage , Anti-Inflammatory Agents/isolation & purification , Antioxidants/administration & dosage , Antioxidants/isolation & purification , Cell Line , Cell Line, Tumor , Diabetes Mellitus, Experimental/drug therapy , Diet, High-Fat , Dose-Response Relationship, Drug , Female , Humans , Hypoglycemic Agents/administration & dosage , Hypoglycemic Agents/isolation & purification , Medicine, Traditional , Metformin/pharmacology , Mice , Mice, Inbred C57BL , Oxidative Stress/drug effects , Plant Extracts/administration & dosage , Rats , Water/chemistry
6.
Sci Rep ; 7(1): 5880, 2017 07 19.
Article in English | MEDLINE | ID: mdl-28724959

ABSTRACT

The metabolic effects of an oral supplementation with a Curcuma longa extract, at a dose nutritionally relevant with common human use, on hepatic metabolism in rats fed a high fructose and saturated fatty acid (HFS) diet was evaluated. High-resolution magic-angle spinning NMR and GC/MS in combination with multivariate analysis have been employed to characterize the NMR metabolite profiles and fatty acid composition of liver tissue respectively. The results showed a clear discrimination between HFS groups and controls involving metabolites such as glucose, glycogen, amino acids, acetate, choline, lysophosphatidylcholine, phosphatidylethanolamine, and ß-hydroxybutyrate as well as an increase of MUFAs and a decrease of n-6 and n-3 PUFAs. Although the administration of CL did not counteract deleterious effects of the HFS diet, some metabolites, namely some n-6 PUFA and n-3 PUFA, and betaine were found to increase significantly in liver samples from rats having received extract of curcuma compared to those fed the HFS diet alone. This result suggests that curcuminoids may affect the transmethylation pathway and/or osmotic regulation. CL extract supplementation in rats appears to increase some of the natural defences preventing the development of fatty liver by acting on the choline metabolism to increase fat export from the liver.


Subject(s)
Dietary Supplements , Liver/metabolism , Plant Extracts/pharmacology , Animals , Betaine/metabolism , Choline/metabolism , Curcuma , Diet, High-Fat , Discriminant Analysis , Fatty Acids , Fructose , Glutathione/metabolism , Least-Squares Analysis , Male , Malondialdehyde/metabolism , Multivariate Analysis , Proton Magnetic Resonance Spectroscopy , Rats, Sprague-Dawley , Triglycerides/metabolism
7.
Talanta ; 170: 119-127, 2017 Aug 01.
Article in English | MEDLINE | ID: mdl-28501147

ABSTRACT

Myeloperoxidase (MPO) is a key enzyme derived from leukocytes which is associated with the initiation and progression of many inflammatory diseases. Increased levels of MPO may contribute to cellular dysfunction and tissues injury by producing highly reactive oxidants such as hypochlorous acid (HOCl). Myeloperoxidase-generated HOCl is therefore considered as a relevant biomarker of oxidative stress-related damage and its quantitation is of great importance to the study of disease progression. In this context, the current study describes a rapid, sensitive and homogeneous fluorescence-based method for detecting the MPO chlorination activity in biological samples. This assay utilizes 7-hydroxy-2-oxo-2H-chromene-8-carbaldehyde oxime as a selective probe for HOCl detection, and is adapted to 96-well microplates to allow high-throughput quantitation of active MPO. The ability of the method to monitor HOCl release was further investigated in hyperglycemic streptozotocin-treated diabetic rats. The data proved that the present assay has a reliable performance when quantitating the active MPO in the plasma of diabetic animals, a feature of inflammatory disease found concomitant with an elevation of protein carbonyls levels and lipid peroxidation and which was negatively correlated with the ratio of reduced-to-oxidized glutathione.


Subject(s)
Diabetes Mellitus, Experimental/metabolism , Enzyme Assays/methods , Hypochlorous Acid/metabolism , Oxidative Stress , Peroxidase/metabolism , Animals , HL-60 Cells , Halogenation , Humans , Male , Peroxidase/blood , Rats , Spectrometry, Fluorescence
8.
Nanotoxicology ; 9(6): 696-705, 2015.
Article in English | MEDLINE | ID: mdl-25325158

ABSTRACT

The broad range of applications of cerium oxide (CeO2) nanoparticles (nano-CeO2) has attracted industrial interest, resulting in greater exposures to humans and environmental systems in the coming years. Their health effects and potential biological impacts need to be determined for risk assessment. The aims of this study were to gain insights into the molecular mechanisms underlying the genotoxic effects of nano-CeO2 in relation with their physicochemical properties. Primary human dermal fibroblasts were exposed to environmentally relevant doses of nano-CeO2 (mean diameter, 7 nm; dose range, 6 × 10(-5)-6 × 10(-3) g/l corresponding to a concentration range of 0.22-22 µM) and DNA damages at the chromosome level were evaluated by genetic toxicology tests and compared to that induced in cells exposed to micro-CeO2 particles (mean diameter, 320 nm) under the same conditions. For this purpose, cytokinesis-blocked micronucleus assay in association with immunofluorescence staining of centromere protein A in micronuclei were used to distinguish between induction of structural or numerical chromosome changes (i.e. clastogenicity or aneuploidy). The results provide the first evidence of a genotoxic effect of nano-CeO2, (while not significant with micro-CeO2) by a clastogenic mechanism. The implication of oxidative mechanisms in this genotoxic effect was investigated by (i) assessing the impact of catalase, a hydrogen peroxide inhibitor, and (ii) by measuring lipid peroxidation and glutathione status and their reversal by application of N-acetylcysteine, a precusor of glutathione synthesis in cells. The data are consistent with the implication of free radical-related mechanisms in the nano-CeO2-induced clastogenic effect, that can be modulated by inhibition of cellular hydrogen peroxide release.


Subject(s)
Cerium/toxicity , DNA Damage , Fibroblasts/drug effects , Mutagens/toxicity , Nanoparticles/toxicity , Oxidative Stress/drug effects , Skin/drug effects , Cells, Cultured , Cerium/chemistry , Colloids , Fibroblasts/metabolism , Fibroblasts/pathology , Humans , Mutagens/chemistry , Nanoparticles/chemistry , Particle Size , Primary Cell Culture , Skin/metabolism , Skin/pathology , Surface Properties
9.
Biochimie ; 94(12): 2569-76, 2012 Dec.
Article in English | MEDLINE | ID: mdl-22835478

ABSTRACT

We have developed a rapid nonradioisotope chemiluminescent assay adapted to high-throughput screening experiments, to evaluate glucose uptake activity in cultured cells. For chemiluminescence quantification of 2-deoxyglucose, we used a luminol oxidation reaction after an enzymatic dephosphorylation of 2-deoxyglucose-6-phosphate. All reactions were performed at 37 °C by consecutive addition of reagents, and the assay is able to quantify 2DG in picomole per well. To confirm the reliability of this method, we have evaluated the dose-effect of insulin, GLUT4 inhibitors and insulin-sensitizing agent on 2DG uptake into 3T3-L1 cells. The results obtained with the assay for 2DG uptake in vitro in the absence or presence of insulin stimulation, were similar to those obtained by the previous radioisotopic and enzymatic methods. We have also used this assay to evaluate the effect of various reactive carbonyl and oxygen species on insulin-stimulated 2DG-uptake into adipocytes. All reactive carbonyl species tested decreased insulin-stimulated glucose uptake in a time- and dose-dependent manner without affecting basal glucose uptake in 3T3-L1 cells. 4-hydroxynonenal was found to be the most potent in the impairment of glucose uptake. This new enzymatic chemiluminescent assay is rapid and useful for measurement of 2DG uptake in insulin-responsive in cultured cells.


Subject(s)
Adipocytes/drug effects , Adipocytes/metabolism , Deoxyglucose/pharmacokinetics , Luminescent Measurements/methods , 3T3-L1 Cells , Acrolein/pharmacology , Aldehydes/pharmacology , Animals , Biological Transport/drug effects , Chromans/pharmacology , Cytochalasin B/pharmacology , Deoxyglucose/metabolism , Hydrogen Peroxide/pharmacology , Hypoglycemic Agents/pharmacology , Insulin/pharmacology , Luminescent Measurements/instrumentation , Mice , Pyruvaldehyde/pharmacology , Reproducibility of Results , Thiazolidinediones/pharmacology , Troglitazone
10.
Biochimie ; 94(8): 1668-75, 2012 Aug.
Article in English | MEDLINE | ID: mdl-22349737

ABSTRACT

The mycotoxin aflatoxin B1 (AFB1) is a carcinogenic food contaminant which is metabolically activated by epoxydation. The metabolism of mycotoxins via the mercapturate metabolic pathway was shown, in general, to lead to their detoxication. Mercapturic acids thus formed (S-substitued-N-acetyl-l-cysteines) may be accumulated in the kidney and either excreted in the urine or desacetylated by Acylase 1 (ACY1) to yield cysteine S-conjugates. To be toxic, the N-acetyl-l-cysteine-S-conjugates first have to undergo deacetylation by ACY 1. The specificity and rate of mercapturic acid deacetylation may determine the toxicity, however the exact deacetylation processes involved are not well known. The aim of this study was to investigate the role of ACY1 in the toxicity of some bioactive epoxides from Aflatoxin B1. We characterized the kinetic parameters of porcine kidney and human recombinant aminoacylase-1 towards some aromatic and aliphatic-derived mercapturates analogue of mycotoxin-mercapturic acids and 3,4-epoxyprecocene, a bioactive epoxide derivated from aflatoxin. The deacetylation of mercapturated substrates was followed both by reverse phase HPLC and by TNBS method. Catalytic activity was discussed in a structure-function relationship. Ours results indicate for the first time that aminoacylase-1 could play an important role in deacetylating mercapturate metabolites of aflatoxin analogues and this process may be in relation with their cyto- and nephrotoxicity in human.


Subject(s)
Acetylcysteine/chemistry , Amidohydrolases/chemistry , Epoxy Compounds/chemistry , Kidney/enzymology , Acetylation , Aflatoxin B1/chemistry , Amidohydrolases/metabolism , Animals , Benzopyrans/chemistry , Catalysis , Humans , Inactivation, Metabolic , Protein Conformation , Structure-Activity Relationship , Substrate Specificity , Swine
11.
J Org Chem ; 77(4): 1789-97, 2012 Feb 17.
Article in English | MEDLINE | ID: mdl-22304384

ABSTRACT

The synthesis and characterization of oxidized bis-thioketal-trispiro dinitroxide biradicals that orient the nitroxides in a rigid, approximately orthogonal geometry are reported. The biradicals show better performance as polarizing agents in dynamic nuclear polarization (DNP) NMR experiments as compared to biradicals lacking the constrained geometry. In addition, the biradicals display improved solubility in aqueous media due to the presence of polar sulfoxides. The results suggest that the orientation of the radicals is not dramatically affected by the oxidation state of the sulfur atoms in the biradical, and we conclude that a biradical polarizing agent containing a mixture of oxidation states can be used for improved solubility without a loss in performance.


Subject(s)
Cyclic N-Oxides/chemical synthesis , Spin Labels/chemical synthesis , Magnetic Resonance Spectroscopy/methods , Oxidation-Reduction , Solubility , Sulfoxides/chemistry , Sulfur/chemistry , Water
12.
Nat Prod Commun ; 6(8): 1151-4, 2011 Aug.
Article in English | MEDLINE | ID: mdl-21922924

ABSTRACT

The essential oils obtained by hydro distillation of the aerial parts of Pituranthos scoparius were collected from different regions of Algeria and gave various yields ranging from 0.6 up to 2.8% (v/w). These samples were analyzed by GC and GC-MS showing the occurrence of monoterpene hydrocarbons and some oxygenated compounds. The major components were alpha-pinene (4.4-35.8%), limonene (0.8-66.5%), bornyl acetate (tr-9.6%), myristicin (tr-31.1) and dill apiole (0.4-47.3%). The aerial parts of P. scoparius could be either very rich or very poor in limonene, myristicin or dill apiole. Cluster analysis shows differences in essential oil compositions of samples coming from the different area collected.


Subject(s)
Apiaceae/chemistry , Oils, Volatile/chemistry , Plant Oils/chemistry , Plant Components, Aerial/chemistry
13.
J Cell Sci ; 124(Pt 8): 1224-30, 2011 Apr 15.
Article in English | MEDLINE | ID: mdl-21406565

ABSTRACT

Proprotein convertases (PCs) are a family of serine proteases that are involved in the post-translational processing and activation of a wide range of regulatory proteins. The upstream role of PCs in the control of many physiological and pathological processes generates a growing interest in understanding their regulation. Here, we demonstrate that the serine protease inhibitor plasminogen activator inhibitor 1 (PAI-1) forms an SDS-stable complex with the PC furin, which leads to the inhibition of the intra-Golgi activity of furin. It is known that elevated PAI-1 plasma levels are correlated with the occurrence of the metabolic syndrome and type 2 diabetes, and we show that PAI-1 reduces the furin-dependent maturation and activity of the insulin receptor and ADAM17: two proteins involved in the onset of these metabolic disorders. In addition to demonstrating that PAI-1 is an intracellular inhibitor of furin, this study also provides arguments in favor of an active role for PAI-1 in the development of metabolic disorders.


Subject(s)
Enzyme Inhibitors/metabolism , Furin/antagonists & inhibitors , Furin/metabolism , Golgi Apparatus/enzymology , Plasminogen Activator Inhibitor 1/metabolism , Cell Line , Furin/genetics , Golgi Apparatus/metabolism , Humans , Intracellular Space/enzymology , Intracellular Space/genetics , Intracellular Space/metabolism , Plasminogen Activator Inhibitor 1/genetics , Protein Binding , Protein Processing, Post-Translational
14.
Chem Biol Interact ; 190(1): 28-34, 2011 Mar 15.
Article in English | MEDLINE | ID: mdl-21216240

ABSTRACT

Numerous reactive oxygen species (ROS) and reactive carbonyl species (RCS) issuing from lipid and sugar oxidation are known to damage a large number of proteins leading to enzyme inhibition and alteration of cellular functions. Whereas studies in literature only focus on the reactivity of one or two of these compounds, we aimed at comparing in the same conditions of incubations (4 and 24h at 37°C) the effects of both various RCS (4-hydroxynonenal, 4-hydroxyhexenal, acrolein, methylglyoxal, glyoxal, malondialdehyde) and ROS (H2O2, AAPH) on the activity of key enzymes involved in cellular oxidative stress: superoxide dismutase (Cu,Zn-SOD), glutathione peroxidase (GPx), glutathione S-transferase (GST) and glucose-6-phosphate dehydrogenase (G6PDH). This was realized both in vitro on purified proteins and MIAPaCa-2 cells. Incubation of these enzymes with RCS resulted in a significant time- and concentration-dependent inhibition for both pure enzymes and in cell lysates. Among all RCS and ROS, hydroxynonenal (HNE) was observed as the most toxic for all studied enzymes except for SOD and is followed by hydrogen peroxide. At 100µM, HNE resulted in a 50% reduction of GPx, 56% of GST, 65% of G6PDH, and only 10% of Cu,Zn-SOD. Meanwhile it seems that concentrations used in our study are closer to biological conditions for ROS than for RCS. H2O2 and AAPH-induced peroxyl radicals may be probably more toxic towards the studied enzymes in vivo.


Subject(s)
Aldehydes/toxicity , Antioxidants/metabolism , Glutathione Transferase/metabolism , Oxidative Stress , Oxidoreductases/metabolism , Reactive Oxygen Species/toxicity , Acrolein/toxicity , Amidines/toxicity , Cell Line, Tumor , Glucosephosphate Dehydrogenase/metabolism , Glutathione Peroxidase/metabolism , Glyoxal/toxicity , Humans , Hydrogen Peroxide/toxicity , Malondialdehyde/toxicity , Pyruvaldehyde/toxicity , Superoxide Dismutase/metabolism
15.
J Biol Chem ; 286(10): 7812-7821, 2011 Mar 11.
Article in English | MEDLINE | ID: mdl-21199874

ABSTRACT

Sulfate reducers have developed a multifaceted adaptative strategy to survive against oxidative stresses. Along with this oxidative stress response, we recently characterized an elegant reversible disulfide bond-dependent protective mechanism in the pyruvate:ferredoxin oxidoreductase (PFOR) of various Desulfovibrio species. Here, we searched for thiol redox systems involved in this mechanism. Using thiol fluorescent labeling, we show that glutathione is not the major thiol/disulfide balance-controlling compound in four different Desulfovibrio species and that no other plentiful low molecular weight thiol can be detected. Enzymatic analyses of two thioredoxins (Trxs) and three thioredoxin reductases allow us to propose the existence of two independent Trx systems in Desulfovibrio vulgaris Hildenborough (DvH). The TR1/Trx1 system corresponds to the typical bacterial Trx system. We measured a TR1 apparent K(m) value for Trx1 of 8.9 µM. Moreover, our results showed that activity of TR1 was NADPH-dependent. The second system named TR3/Trx3 corresponds to an unconventional Trx system as TR3 used preferentially NADH (K(m) for NADPH, 743 µM; K(m) for NADH, 5.6 µM), and Trx3 was unable to reduce insulin. The K(m) value of TR3 for Trx3 was 1.12 µM. In vitro experiments demonstrated that the TR1/Trx1 system was the only one able to reactivate the oxygen-protected form of Desulfovibrio africanus PFOR. Moreover, ex vivo pulldown assays using the mutant Trx1(C33S) as bait allowed us to capture PFOR from the DvH extract. Altogether, these data demonstrate that PFOR is a new target for Trx1, which is probably involved in the protective switch mechanism of the enzyme.


Subject(s)
Bacterial Proteins/metabolism , Desulfovibrio vulgaris/metabolism , Pyruvate Synthase/metabolism , Thioredoxins/metabolism , Anaerobiosis/physiology , Bacterial Proteins/genetics , Desulfovibrio vulgaris/genetics , Disulfides/metabolism , Mutation , NAD/genetics , NAD/metabolism , Oxidation-Reduction , Pyruvate Synthase/genetics , Reactive Oxygen Species/metabolism , Sulfhydryl Compounds/metabolism , Thioredoxins/genetics
16.
Antioxid Redox Signal ; 15(6): 1639-53, 2011 Sep 15.
Article in English | MEDLINE | ID: mdl-21235351

ABSTRACT

The p53-transcriptional target TP53INP1 is a potent stress-response protein promoting p53 activity. We previously showed that ectopic overexpression of TP53INP1 facilitates cell cycle arrest as well as cell death. Here we report a study investigating cell death in mice deficient for TP53INP1. Surprisingly, we found enhanced stress-induced apoptosis in TP53INP1-deficient cells. This observation is underpinned in different cell types in vivo (thymocytes) and in vitro (thymocytes and MEFs), following different types of injury inducing either p53-dependent or -independent cell death. Nevertheless, absence of TP53INP1 is unable to overcome impaired cell death of p53-deficient thymocytes. Stress-induced ROS production is enhanced in the absence of TP53INP1, and antioxidant NAC complementation abolishes increased sensitivity to apoptosis of TP53INP1-deficient cells. Furthermore, antioxidant defenses are defective in TP53INP1-deficient mice in correlation with ROS dysregulation. Finally, we show that autophagy is reduced in TP53INP1-deficient cells both at the basal level and upon stress. Altogether, these data show that impaired ROS regulation in TP53INP1-deficient cells is responsible for their sensitivity to induced apoptosis. In addition, they suggest that this sensitivity could rely on a defect of autophagy. Therefore, these data emphasize the role of TP53INP1 in protection against cell injury.


Subject(s)
Apoptosis , Fibroblasts/physiology , Nuclear Proteins/metabolism , Reactive Oxygen Species/metabolism , Thymus Gland/cytology , 2,6-Dichloroindophenol/pharmacology , Animals , Cell Cycle , Cells, Cultured , Fibroblasts/cytology , Gene Expression , Glutathione/metabolism , Mice , Mice, 129 Strain , Mice, Inbred C57BL , Nuclear Proteins/genetics , Oxidation-Reduction , Oxidative Stress/physiology
17.
Food Chem Toxicol ; 48(10): 2599-606, 2010 Oct.
Article in English | MEDLINE | ID: mdl-20600536

ABSTRACT

Hydromethanolic extracts from 18 Algerian medicinal plants were screened for their phenolic contents and radical scavenging activities. The phenolic extract of Cleome arabica (Capparaceae) was found to be the most active one. Purification of this extract by semi-preparative high performance liquid chromatography led to the isolation and identification of new steroid derivative. The structure of the active principle is proposed as (17-(4-hydroxy-1,5-dimethylhexyl)-2,3,7-(acetyloxy) gona-1,3,5(10)-trien-15-ol). Compared to six other standard antioxidants which were ascorbic acid, α-tocopherol, Trolox, (+) catechin, p-coumaric acid and gallic acid, the isolated compound was found to be significantly more active in the radical scavenging assay using 2,2-diphenyl-1-picrylhydrazyl (DPPH). Similar results were obtained in the hemolysis assay. The antioxidant capacities of the methanolic extract of C. arabica and its principle compound indicate that this plant may be an important source of chemopreventive and chemotherapeutic natural products activity.


Subject(s)
Antioxidants , Cleome/chemistry , Plants, Medicinal/chemistry , Steroids/pharmacology , Algeria , Biphenyl Compounds , Calibration , Chromatography, High Pressure Liquid , Free Radical Scavengers/chemistry , Free Radical Scavengers/pharmacology , Hemolysis/drug effects , Humans , In Vitro Techniques , Magnetic Resonance Spectroscopy , Phenols/chemistry , Phenols/pharmacology , Picrates , Spectrophotometry, Ultraviolet , Steroids/isolation & purification
18.
Int J Vitam Nutr Res ; 75(1): 11-8, 2005 Jan.
Article in English | MEDLINE | ID: mdl-15830916

ABSTRACT

Assessment of the antioxidant activity of vitamins and other compounds is of interest in the understanding of their in vivo effects. In this study, we have investigated the activity of several lipid and water-soluble vitamins in human whole blood. Measurements were carried out using a biological test that enables the evaluation of both red blood cells and plasma resistance against free radical activity induced by 2,2'-azobis (2-amidinopropane)hydrochloride (AAPH). Antioxidant activity of vitamins has been determined by using the biological test versus chemical methods (chemiluminescence, DMPD radical). We have observed strong anti-oxidant potentials for vitamins B6 and B9 with biological tests, but not with chemical methods. At 10 microM, the vitamin B9 efficiency in inhibiting radical-induced red blood cell hemolysis was almost three times higher than vitamin C efficiency and two times higher than alpha-tocopherol efficiency. Antioxidant activity was not observed for vitamins B1 or B2, nor for retinol. The weak activity of beta-carotene still remains to be investigated particularly in relation to oxygen pressure. Our study demonstrated that the biological test is more useful than the chemical methods employed in this instance, for the evaluation of antioxidant capacity of lipophilic and putatively biologically active compounds.


Subject(s)
Antioxidants/pharmacology , Fluorescent Dyes , Luminescent Measurements/methods , Phenylenediamines , Vitamins/blood , Vitamins/pharmacology , Amidines/pharmacology , Antioxidants/metabolism , Ascorbic Acid/blood , Ascorbic Acid/pharmacology , Biological Assay , Caffeic Acids/blood , Caffeic Acids/pharmacology , Dose-Response Relationship, Drug , Hemolysis/drug effects , Humans , Oxidants/pharmacology , Reference Values , Solubility , Vitamin A/blood , Vitamin A/pharmacology , Vitamin B Complex/blood , Vitamin B Complex/pharmacology , alpha-Tocopherol/blood , alpha-Tocopherol/pharmacology , beta Carotene/blood , beta Carotene/pharmacology
19.
Biochim Biophys Acta ; 1621(1): 1-8, 2003 Apr 07.
Article in English | MEDLINE | ID: mdl-12667604

ABSTRACT

This study deals with the activity of various vitamins against the radical-mediated oxidative damage in human whole blood. We have used a biological method that allows both the evaluation of plasma and that of red blood cell resistance against the free radicals induced by 2,2'-azobis (2-amidinopropane) hydrochloride (AAPH). Spin trapping measures using mainly 5-(diethoxyphosphoryl)-5-methyl-1-pyrolline N-oxide nitrone (DEPMPO) were carried out under several conditions to identify the free radicals implicated in this test. Only the oxygenated-centred radical generated from AAPH was found highly reactive to initiate red blood cell lysis. With DEPMPO only alkoxyl radicals were observed and no evidence was found for alkylperoxyl radicals. The antioxidant activity of several lipid- and water-soluble vitamins has been assessed by the biological assay and through two chemical methods. We have noticed high antioxidant activities for tocopherols (in the order delta>gamma>alpha) in the biological test but not through chemical methods. At 1 microM, the delta-tocopherol efficiency in inhibiting radical-induced red blood cell hemolysis was three times as high as the alpha-tocopherol efficiency. For beta-carotene no significant activity even in whole blood was shown. Highly surprising antioxidant activities were observed for acid folic and pyridoxine, compared to ascorbic acid. At 10 microM, the effectiveness of folic acid was almost three times as high as vitamin C. The biological test seems clinically more relevant than most other common assays because it can detect several classes of antioxidants.


Subject(s)
Antioxidants/pharmacology , Blood , Erythrocytes/drug effects , Hemolysis/drug effects , Oxidants/analysis , Vitamins/pharmacology , Amidines/analysis , Antioxidants/chemistry , Electron Spin Resonance Spectroscopy , Endpoint Determination , Erythrocyte Membrane/drug effects , Erythrocytes/chemistry , Free Radical Scavengers , Free Radicals/chemistry , Luminescent Measurements , Oxygen , Spin Trapping , Vitamins/chemistry
20.
Environ Health Perspect ; 110(5): 479-86, 2002 May.
Article in English | MEDLINE | ID: mdl-12003751

ABSTRACT

Oxidative damage is increasingly recognized as playing an important role in the pathogenesis of several diseases such as cancer and cardiovascular diseases. Using a biologic test based on whole blood resistance to free-radical aggression, we sought to evaluate lifestyle factors that may contribute to the normal variability of the overall antioxidant status. We assessed this global antiradical defense capacity in 88 men and 96 women in relation to information on lifestyle obtained by questionnaire. In our relatively young, healthy population, we found a weak negative relation between male sex or aging and the resistance to oxidant stress. Among the factors studied, nonsmoking, vitamin and/or mineral supplementation, and regular physical activity were closely associated with an increased overall antioxidant capacity. Conversely, the antioxidant potential was negatively related to tobacco smoking; psychologic stress; alcohol consumption; moderate vegetable, low fruit, and low fish consumption; and, to a lesser extent, high natural ultraviolet light exposure. Thus, we were able to determine "unhealthy" and "healthy" lifestyle patterns that truly contributed to the variation of individual antioxidant capacity. We conclude that lifestyle determinants of cancer and cardiovascular risks were associated with a decreased overall antioxidant status as dynamically measured by means of a biologic test. Thus, the evaluation of the total human resistance against free-radical aggression, taking into account nutritional habits, lifestyle, and environmental factors, may be useful in preventive medicine as a precocious diagnosis to identify healthy subjects who are at risk for free-radical-mediated diseases.


Subject(s)
Antioxidants/pharmacology , Free Radicals/adverse effects , Health Status , Life Style , Oxidative Stress , Adult , Age Factors , Aged , Diet , Female , Hemolysis , Humans , Male , Middle Aged , Risk Assessment , Sex Factors , Smoking/adverse effects
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