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PubMed1989

[The activity of antioxidant enzymes in the saliva of normal children].

Salivary total antioxidant activity and the activities of catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, and glutathione transferase were measured in 30 normal children with different salivary gland functioning in different seasons. The activities of all the examined enzymes were detected in the saliva. Studies of nonstimulated saliva are recommended to define the normal values and to develop diagnostic tests on the basis of estimation of peroxidation and antioxidant defense parameters.

Adolescent↗
PubMed1987

[Activity of enzymes of glutathione metabolism and regulation by cAMP in human tumors].

Tumors were studied in 38 patients, tissues located far away from tumor being used as control. Breast and stomach tumors revealed relatively high levels of glutathione reductase, glutathione-S-transferase (I) and, particularly, gamma-glutamyl transferase (II). The said changes were not observed in colorectal tumors. Gamma-glutamyl transferase (II) may be used as a marker for breast and stomach malignancies in man but it is not a universal and absolutely specific marker for all tumors. The activity of glutathione peroxidase (III) either did not change or decreased. The activating effect of cAMP on III and I remained generally unchanged in all tumors studied.

Adult↗
PubMedDate not supplied

Effects of bendazac L-lysine salt on some metabolic enzymes of glutathione in the rabbit lens after X-irradiation.

The effect of (1-benzoyl-1H-indazol-3-yl)oxylacetate L-Lysine (bendazac-lysine) on some enzymatic activities involved in the metabolism of reduced glutathione (GSH) was studied in the rabbit lens during developing cataract induced by a single dose of X-rays (2000 rads). The specific activities of glutathione reductase (G.R.), glutathione peroxidase (GSH.Px) and glutathione S-transferase (GSHS-tr.) do not change following irradiation and treatment with bendazac-lysine. The activity of the same enzymes expressed as a function of water soluble proteins (WSP) per lens significantly decreases (P less than 0.01) as compared to controls in the irradiated lens not treated with bendazac-lysine (ILNTB) at the 8th week, whereas no significant decrease as compared to controls is observed in the irradiated lens treated with bendazac-lysine (ILTB). In the ILNTB the specific activity of glucose-6-phosphate dehydrogenase (G6PDH) is reduced by 10% after 0.3 weeks and by 29% after 12 weeks. In the ILTB the specific activity of G6PDH is reduced by 8% after 0.3 weeks and by 14.5% after 12 weeks. The specific activity of superoxide dismutase (SOD) in the ILNTB is reduced by 19% after 0.3 weeks and reached 31% after 12 weeks. In the ILTB the specific activity of SOD is reduced by 11% after 0.3 weeks and 19.8% after 12 weeks. The mechanism of protective effect of bendazac-lysine on cataract is discussed.

Animals↗
PubMed1995

N,S-bis-fluorenylmethoxycarbonylglutathione: a new, very potent inhibitor of mammalian glyoxalase II.

A very potent competitive inhibitor of mammalian glyoxalase II activity, N,S-bis-fluorenylmethoxycarbonylglutathione (DiFMOC-G) has been synthesized and characterized. The Ki value for inhibition of glyoxalase II purified from calf liver is 0.08 microM. The Ki values for glyoxalase I inhibitions range from 285 to 500 fold higher than the values obtained for glyoxalase II inhibitions, depending on the source of the enzyme. Among other enzymes involved in glutathione metabolism, such as glutathione S-transferase, glutathione reductase, and glutathione peroxidase, only glutathione S-transferase is inhibited to a small extent by DiFMOC-G. Diesters of DiFMOC-G were prepared in order to improve transport of DiFMOC-G into mammalian tumor cells (rat adrenal pheochromocytoma, PC-12) in culture. Among the diesters synthesized, diisopropyl DiFMOC-G was found to be the most inhibitory to cell viability, with a [I]0.5 value of 3 microM.

Animals↗
PubMed1994

Ameliorative capacities of vitamins and monothiols post therapy in the restoration of methylmercury altered glutathione metabolism.

The recovery of glutathione and its metabolising enzymes (glutathione disulfide reductase, glutathione peroxidase, thiol transferase, gamma-glutamyl transpeptidase and glutathione transferase) along with sulfhydryl groups and byproduct of lipid peroxidation (malondialdehyde) in the brain, spinal cord, kidney and liver of mice, altered during methylmercury chloride (MMC) intoxication, is recorded in post-therapeutic treatment with vitamins and monothiols. For this purpose ten groups of animals were intoxicated with 1 mg/kg MMC/day for 7 days. Out of these, one group was sacrificed on 8th day and one group was kept without toxicant for another seven days before sacrificing on 15th day. Study shows significant decrease of various biomolecules of glutathione metabolism during MMC application, which are further decreased with increasing the duration on 15th day. The trend is same in all the tissues with few exceptions. However, malondialdehyde, a byproduct of lipid peroxidation, is increased with increasing the duration after intoxication. Study also shows a significant recovery (in many cases a complete control level) of most of the components with one or the other chelator or with their combined therapy. Therefore, it is concluded from overall study that vitamins B complex and E, GSH (or its precursor NAHT) either alone or in combinations, are quite suitable for methylmercury post-therapy.

Animals↗
PubMed1992

Antioxidants and Manganese Deficiency in Needles of Norway Spruce (Picea abies L.) Trees.

Chlorotic and green needles from Norway spruce (Picea abies L.) trees were sampled in the Calcareous Bavarian Alps in winter. The needles were used for analysis of the mineral and pigment contents, the levels of antioxidants (ascorbate, glutathione), and the activities of protective enzymes (superoxide dismutase, catalase, ascorbate peroxidase, monodehydroascorbate radical reductase, dehydroascorbate reductase, glutathione reductase). In addition, the activities of two respiratory enzymes (glucose-6-phosphate dehydrogenase, NAD-malate dehydrogenase), which might provide the NADPH necessary for functioning of the antioxidative system, were determined. We found that chlorotic needles were severely manganese deficient (3 to 6 micrograms Mn per gram dry weight as compared with up to 190 micrograms Mn per gram dry weight in green needles) but had a similar dry weight to fresh weight ratio, had a similar protein content, and showed no evidence for enhanced lipid peroxidation as compared with green needles. In chlorotic needles, the level of total ascorbate and the activities of superoxide dismutase, monodehydroascorbate radical reductase, NAD-malate dehydrogenase, and glucose-6-phosphate dehydrogenase were significantly increased, whereas the levels of ascorbate peroxidase, dehydroascorbate reductase, glutathione reductase, and glutathione were not affected. The ratio of ascorbate to dehydroascorbate was similar in both green and chlorotic needles. These results suggest that in spruce needles monodehydroascorbate radical reductase is the key enzyme involved in maintaining ascorbate in its reduced state. The reductant necessary for this process may have been supplied at the expense of photosynthate.

Journal Article↗
PubMed2005

Riboflavin deficiency causes protein and DNA damage in HepG2 cells, triggering arrest in G1 phase of the cell cycle.

Eukaryotes convert riboflavin to flavin adenine dinucleotide, which serves as a coenzyme for glutathione reductase and other enzymes. Glutathione reductase mediates the regeneration of reduced glutathione, which plays an important role in scavenging free radicals and reactive oxygen species. Here we tested the hypothesis that riboflavin deficiency decreases glutathione reductase activity in HepG2 liver cells, causing oxidative damage to proteins and DNA, and cell cycle arrest. As a secondary goal, we determined whether riboflavin deficiency is associated with gene expression patterns indicating cell stress. Cells were cultured in riboflavin-deficient and riboflavin-supplemented media for 4 days. Activity of glutathione reductase was not detectable in cells cultured in riboflavin-deficient medium. Riboflavin deficiency was associated with an increase in the abundance of damaged (carbonylated) proteins and with increased incidence of DNA strand breaks. Damage to proteins and DNA was paralleled by increased abundance of the stress-related transcription factor GADD153. Riboflavin-deficient cells arrested in G1 phase of the cell cycle. Moreover, oxidative stress caused by riboflavin deficiency was associated with increased expression of clusters of genes that play roles in cell stress and apoptosis. For example, the abundance of the pro-apoptotic pleiomorphic adenoma gene-like 1 gene was 183% greater in riboflavin-deficient cells compared with riboflavin-sufficient controls. We conclude that riboflavin deficiency is associated with oxidative damage to proteins and DNA in liver cells, leading to cell stress and G1 phase arrest.

Cell Line↗
PubMed1987

Role of glutathione metabolizing enzymes in nickel mediated induction of hepatic glutathione.

The administration of nickel to rats resulted in a dose-dependent increase in the level of hepatic glutathione and in the activities of glutathione reductase and glutathione-S-transferase with a concomitant decrease in the activities of glutathione peroxidase and gamma-glutamyl transpeptidase. The increase in hepatic glutathione may be due to the decrease in the activities of glutathione utilizing enzymes and increase in the activity of glutathione reductase leading to the increased turnover of glutathione.

Animals↗
PubMed1994

Chinifur, a selective inhibitor and "subversive substrate" for Trypanosoma congolense trypanothione reductase.

Nitrofurans with aromatic and heterocyclic substituents inhibit Trypanosoma congolense trypanothione reductase (TR) and yeast glutathione reductase (GR), acting as uncompetitive inhibitors vs. NADPH and noncompetitive or uncompetitive inhibitors vs. disulfide substrate. Many of these compounds inhibited trypanothione reductase more efficiently than glutathione reductase. Chinifur (2-[5'-nitro(furo-2'-yl)-ethene-1-yl]-4(N,N-diethylamino)-1-methyl-but-1 -yl - aminocarbonyl-4-quinoline) was the most selective inhibitor of, and free radical-generating substrate for, trypanothione reductase (Ki = 4.5 microns, TN = 3 s-1, TN/Km = 3.2 x 10(4) M-1 s-1), only weakly inhibiting glutathione reductase (Ki = 100 microns). These findings point to the importance of hydrophobic interactions in the design of redox active heteroaromatic compounds acting as selective inhibitors of, and "subversive substrates" for, trypanothione reductase.

Animals↗
PubMed1989

Chromium (V) and hydroxyl radical formation during the glutathione reductase-catalyzed reduction of chromium (VI).

Electron spin resonance measurements provide evidence for the formation of long-lived Cr(V) intermediates in the reduction of Cr(VI) by glutathione reductase in the presence of NADPH and for the hydroxyl radical formation during the glutathione reductase catalyzed reduction of Cr(VI). Hydrogen peroxide suppresses Cr(V) and enhances the formation of hydroxyl radicals. Thus Cr(V) intermediates catalyze generation of hydroxyl radicals from hydrogen peroxide through a Fenton-like reaction. Thus the mechanism of Cr(VI) toxicity might involve the interaction between macromolecules and the hydroxyl radicals.

Animals↗
PubMed1991

Drought Stress, Enzymes of Glutathione Metabolism, Oxidation Injury, and Protein Synthesis in Tortula ruralis.

The activities of glutathione reductase (EC 1.6.4.2), glutathione peroxidase (EC 1.11.1.9), and glutathione S-transferase (EC 2.5.1.18) were found to increase during slow drying or during rehydration following rapid drying of the drought-tolerant moss Tortula ruralis. Little change was observed in the activity of malate deydrogenase (NAD(+) oxidoreductase, EC 1.1.1.37) during dehydration or subsequent rehydration. When the tissue was treated with cycloheximide, actinomycin D, or cordycepin, the increase in the activities of glutathione reductase and glutathione S-transferase was largely prevented while effect on glutathione peroxidase was much smaller. Concomitantly, oxidized glutathione (GSSG) as percentage of total glutathione increased. GSSG level was correlated positively with the levels of lipid peroxidation and solute leakage and negatively with the rate of protein synthesis. The results show that GSSG level is a good indicator of oxidation stress and provide support to the suggestion that GSSG mediates, at least in part, the drought stress-induced inhibition of protein synthesis.

Journal Article↗
PubMed2002

Crystallization and preliminary X-ray crystallographic analysis of glutathione amide reductase from Chromatium gracile.

The Chromatiaceae-specific glutathione amide reductase (GAR) belongs to the well known family of the glutathione reductases, even though differences in both substrate (glutathione amide instead of glutathione) and coenzyme (NADH instead of NADPH) specificities are reported. Crystals of the GAR enzyme from Chromatium gracile have been grown at 294 K by the hanging-drop vapour-diffusion method using lithium sulfate as a precipitant in the presence of nickel ions. The crystals belong to space group P4(1), with unit-cell parameters a = b = 71.93, c = 223.85 A, alpha = beta = gamma = 90 degrees and one dimer per asymmetric unit. A full set of X-ray diffraction data was collected to 2.1 A resolution with a completeness of 95.2%. Structure determination via the method of molecular replacement is under way.

Bacterial Proteins↗
PubMed2002

Changes in glutathione-redox balance induced by hexachlorocyclohexane and lindane in CHO-K1 cells.

1. The basal cytotoxic effect of the organochlorine pesticides hexachlorocyclohexane and lindane on CHO-K1 cultures was assessed at fractions of their lethal doses as determined by the neutral red incorporation (NRI) assay (NRI(6.25), NRI(12.5) and NRI(25)). The sulphur-redox cycle enzymes glutathione peroxidase, glutathione reductase and glutathione S-transferase, and total and oxidized glutathione were evaluated at several points during the standard growth curve of the cultures. 2. After incubation with each compound for 24 h, both glutathione peroxidase and reductase showed a substantial increase at the lowest exposure doses (NRI(6.25))--more significantly for lindane than for 1,2,3,4,5,6-hexachlorocyclohexane (HCH)--and dropped at higher doses of both compounds. The reduced and oxidized glutathione content was greatly diminished at the lower exposures, whereas the total glutathione content was higher at NRI(12.5) values. 3. Changes in cell membrane integrity were assessed for a wide range of pesticide concentrations with the lactate dehydrogenase release assay and lipid peroxidation. Membrane leakage and peroxide production were significantly enhanced at concentrations of HCH 50 microg ml(-1), although this effect was not significant at lindane concentrations < 200 microg ml(-1). 4. Lipid peroxidation increased with exposure to HCH at concentrations as low as NRI(6.25), whereas in the case of lindane, this increase was only significant at doses of NRI(25) and above.

Animals↗
PubMed2001

Characterization of glutathione amide reductase from Chromatium gracile. Identification of a novel thiol peroxidase (Prx/Grx) fueled by glutathione amide redox cycling.

Among the Chromatiaceae, the glutathione derivative gamma-l-glutamyl-l-cysteinylglycine amide, or glutathione amide, was reported to be present in facultative aerobic as well as in strictly anaerobic species. The gene (garB) encoding the central enzyme in glutathione amide cycling, glutathione amide reductase (GAR), has been isolated from Chromatium gracile, and its genomic organization has been examined. The garB gene is immediately preceded by an open reading frame encoding a novel 27.5-kDa chimeric enzyme composed of one N-terminal peroxiredoxin-like domain followed by a glutaredoxin-like C terminus. The 27.5-kDa enzyme was established in vitro to be a glutathione amide-dependent peroxidase, being the first example of a prokaryotic low molecular mass thiol-dependent peroxidase. Amino acid sequence alignment of GAR with the functionally homologous glutathione and trypanothione reductases emphasizes the conservation of the catalytically important redox-active disulfide and of regions involved in binding the FAD prosthetic group and the substrates glutathione amide disulfide and NADH. By establishing Michaelis constants of 97 and 13.2 microm for glutathione amide disulfide and NADH, respectively (in contrast to K(m) values of 6.9 mm for glutathione disulfide and 1.98 mm for NADPH), the exclusive substrate specificities of GAR have been documented. Specificity for the amidated disulfide cofactor partly can be explained by the substitution of Arg-37, shown by x-ray crystallographic data of the human glutathione reductase to hydrogen-bond one of the glutathione glycyl carboxylates, by the negatively charged Glu-21. On the other hand, the preference for the unusual electron donor, to some extent, has to rely on the substitution of the basic residues Arg-218, His-219, and Arg-224, which have been shown to interact in the human enzyme with the NADPH 2'-phosphate group, by Leu-197, Glu-198, and Phe-203. We suggest GAR to be the newest member of the class I flavoprotein disulfide reductase family of oxidoreductases.

Amino Acid Sequence↗
PubMed1994

Thymic peptides increase glutathione level and glutathione disulfide reductase activity in vascular endothelial cells.

The glutathione redox cycle plays an important role in antioxidant and detoxification mechanisms. We recently reported that a calf thymic peptide (TP) protected vascular endothelial cells from oxidant injury induced by hydrogen peroxide. Using electrophoresis and amino acid sequencing analysis, we have now shown that TP consists of two peptides. The fast-moving peptide has 9 amino acid residues at the NH2 terminal and accounts for 92% of total quantity, while the other peptide has 18 amino acid residues at the NH2 terminal and amounts to 8%. The present study investigated the effect of TP on glutathione redox cycle. Confluent monolayers of bovine pulmonary artery endothelial cells (PAEC) were incubated with TP (12.5-100 micrograms/mL) for 24-48 h. TP caused a dose-dependent increase in glutathione (GSH) level and glutathione disulfide reductase activity but no significant change in GSH peroxidase activity. Exposure of PAEC to an organic oxidant t-butyl hydroperoxide (tBHP) resulted in decreased GSH level, increased lipid peroxidation, and elevated leakage of intracellular lactate dehydrogenase. Preincubation of PAEC with TP prevented these changes induced by tBHP. The data suggest that the antioxidant effect of TP may be due, at least in part, to its modulation of the GSH redox cycle in vascular endothelial cells. TP may thus be considered a new antioxidant with novel activities in addition to being an immune regulator.

Amino Acid Sequence↗
PubMed1982

Isolation and mapping of glutathione reductase-negative mutants of Escherichia coli K12.

Two independent mutants defective in glutathione reductase (EC 1.6.4.2) were isolated in an Escherichia coli K12 strain lysogenized with bacteriophage Mu. The prophage was lost (and the ability to reduce glutathione regained) by 32% of the xylose-positive transductants when T4GT7 was used as the vector, but the markers were not cotransduced by P1. Similarly, the prophage site and malA were cotransduced by T4GT7 but not by P1. The gor gene maps between min 77 and 78 on the E. coli genome, and the mutation causes no growth defect.

Bacteriophage mu↗
PubMed2003

Immunosuppression and oxidative stress induced by acute and chronic exposure to cocaine in rat.

The objective of the present study was to verify if immunosuppression caused by cocaine (CO) can be mediated, at least in part, by increased formation of oxidative metabolites and reactive oxygen species (ROS) in rat. Pharmacokinetics of cocaine and its metabolites, cell-mediated immune function and cytokines production, biomarkers of cell redox state maintenance and lipidic peroxidation, and variations of activity in the enzymatic systems involved in cell antioxidant defence were measured in spleen of Wistar rats acutely and chronically treated with cocaine.C(max), AUC, and t(1/2) of norcocaine (NC) significantly increased after chronic exposure to cocaine while kinetic parameters of benzoylecgonine (BE) significantly decreased. A decrease in cultured T-lymphocytes proliferation and natural killer (NK) cell activity, a high increase of immunosuppressive cytokines and a switch from Th1-type cytokines to Th2-type cytokines together with an unbalance toward anti-inflammatory cytokines recovered within 4 h after acute treatment while subsisted for 14 days after chronic treatment. A significant increase in ascorbic acid (AA), reduced glutathione and glutathione reductase (GR) with a simultaneous decrease in oxidized glutathione were observed in the first hours after acute administration. Conversely, the increase in oxidized glutathione and malondialdehyde (MDA) production and the simultaneous depletion of reduced glutathione and ascorbic acid persisted at least 24 h after chronic cocaine treatment as well as the increase in the activities of glutathione reductase, glutathione peroxidase (GPx) and superoxide dismutase (SOD). The results suggest that chronic cocaine administration affects cellular enzyme and non-enzyme-mediated antioxidant defence systems and promotes immunotoxicity in rat. Cocaine N-oxidative metabolism may be an indirect contributor, via oxidative stress.

Animals↗