Antioxidant enzymes, hydrogen peroxide metabolism, and respiration in rat heart during experimental hyperammonemia

The effects of toxic ammonia doses on H₂O₂ metabolism, energy metabolism, and antioxidant enzyme activities in rat heart were studied. Ammonium acetate administration to animals proved to increase total superoxide dismutase (SOD), catalase, and glutathione peroxidase activities in the heart cytoplasmic fraction as well as Mn-SOD, catalase, and glutathione reductase in heart mitochondria. Conversely, ammonia inhibited the same activities in the brain, liver, and erythrocytes. Hyperammonemia had no effect on the levels of ATP, ADP and total adenine nucleotides in the heart but decreased them in the brain. Ammonia impaired oxidative phosphorylation and increased the rate of H₂O₂ production in heart and brain mitochondria. The ammonia concentration inhibiting antioxidant enzymes in the liver and brain can be insufficient for such effect in the heart.     

Comparative study of the antioxidant defence systems in the erythrocytes of australian marsupials and monotremes

A comparison of the erythrocyte (RBC) antioxidant metabolites and enzymes in nine marsupial and two monotreme species was carried out. Reduced glutathione (GSH) concentrations were comparable with those reported for other marsupial and eutherian species. An important finding was that the erythrocytes of the southern hairy nosed wombat regenerated GSH faster than the erythrocytes from its close relative, the common wombat. The activities of glutathione-S-transferase, NADH-methaemoglobin reductase, Superoxide dismutase, and glutathione peroxidase (GSH-Px), showed similar levels and extents of variation as those observed in other marsupial and eutherian species. Catalase activities in the marsupials were lower than those measured in the two monotreme species and much lower than those reported in eutherian species. A negative correlation, significant at P < 0.05, was observed between GSH-Px and catalase activities in the RBC of the marsupials. Since both these enzymes “detoxify” H₂O₂, there appears to be a reciprocal relationship between the activities of these enzymes in marsupial RBC     

Enzyme defense against reactive oxygen derivatives. II. Erythrocytes and tumor cells

Summary The enzymatic destruction of oxidizing products produced during metabolic reduction of oxygen in the cell (such as singlet oxygen, H₂O₂ and OH radical) involves the concerted action of superoxide dismutase-which removes O ₂ ^- and yields H₂O₂-and H₂O₂ removing enzymes such as catalase and glutathione peroxidase. A difference in distribution or ratio of these enzymes in various tissues may result in a different reactivity of oxygen radicals.It was found that in red blood cells superoxide dismutase and catalase are extracted in the same fraction as hemoglobin, while glutathione peroxidase appears to be loosely bound to the cellular structure. This suggests that in red blood cells catalase acts in series with superoxide dismutase against bursts of oxygen radicals formed from oxyhemoglobin, while glutathione & peroxidase may protect the cell membrane against low concentrations of H₂O₂. On the other hand, catalase activity is absent in various types of ascites tumor cells, while glutathione peroxidase and superoxide dismutase are found in the cytoplasm. However, the peroxidase/dismutase ratio is lower than in liver cells, and this may provide an explanation for the higher susceptibility of tumor cells to treatments likely to involve oxygen radicals.     

Oxidative Stress Responses in the Unicellular Cyanobacterium Synechococcus Pcc 7942

Oxidative stress responses were tested in the unicellular cyanobacterium synechococcus PCC 7942 (R-2). Cells were exposed to hydrogen peroxide, cumene hydroperoxide and high light intensities. The extent and time course of oxidative stress were related to the activities of ascorbate peroxidase and catalase. Ascorbate peroxidase was found to be the major enzyme involved in the removal of hydrogen peroxide under the tested oxidative stresse. Catalase activity was inhibited in cells, treated with high H₂O₂ concentrations, and was not induced under photooxidative stress. Catalase was specifically induced in cells treated with cumene hydroperoxide.

Superoxide dismutase activity increased under conditions generating superoxide, such as high light intensities. The induction of the antioxidative enzymes was light dependent and was inhibited by chloramphenicol.     

Induction of Betalain Pigmentation in Hairy Roots of Red Beet under Different Radiation Sources

The effects of aluminum on lipid peroxidation and activities of antioxidative enzymes were investigated in detached rice leaves treated with 0 to 5 mM AlCl₃ at pH 4.0 in the light. AlCl₃ enhanced the content of malondialdehyde but not the content of H₂O₂. Superoxide dismutase activity was reduced by AlCl₃, while catalase and glutathione reductase activities were increased. Peroxidase and ascorbate peroxidase activities were increased only after prolonged treatment, when toxicity occurred. The results give evidence that Al treatment caused oxidative stress and in turn, it caused lipid peroxidation.     

Increase in glutathione peroxidase activity in erythrocytes from trisomy 21 subjects.

Glutathione peroxidase activity has been measured in erythrocytes from normal subjects and from trisomy 21 patients. The latter cases show about 50 % increase of this enzyme similar to the increase observed for superoxide dismutase (erythrocuprein) suggesting either localisation of the gene for glutathione peroxidase on chromosome 21 (as is the case for erythrocuprein) or regulation of this enzyme by intracellular levels of O₂^$\text{?}$, H₂O₂ or superoxide dismutase.     

Erythrocyte antioxidant enzymes in multiple sclerosis and the effect of hyperbaric oxygen

The activities of catalase, glutathione peroxidase, and glutathione reductase, were not significantly different from normal whereas that of superoxide dismutase was decreased (P<0.05) in erythrocytes from patients with multiple sclerosis. Assay of the lipid peroxidation product, malondialdehyde, after incubation of erythrocytes with 10 mM H₂O₂ under carefully controlled conditions (peroxide stress test) demonstrated that MS erythrocytes are significantly (P<0.001) less susceptible to H₂O₂-induced lipid peroxidation in vitro. This finding suggests that the level of an endogenous antioxidant, possibly vitamin E, may be elevated in MS red cells. After treatment with hyperbaric O₂, the activity of MS erythrocyte catalase is significantly (P<0.01) elevated by 2–6-fold.     

Tolerance of the yeast Yarrowia lipolytica to oxidative stress

The adaptive response of the yeast Yarrowia lipolytica to the oxidative stress induced by the oxidants hydrogen peroxide, menadione, and juglone has been studied. H₂O₂, menadione, and juglone completely inhibited yeast growth at concentrations higher than 120, 0.5, and 0.03 mM, respectively. The stationary-phase yeast cells were found to be more resistant to the oxidants than the exponential-phase cells. The 60-min pretreatment of logarithmic-phase cells with nonlethal concentrations of H₂O₂ (0.3 mM), menadione (0.05 mM), and juglone (0.005 mM) made the cells more resistant to high concentrations of these oxidants. The adaptation of yeast cells to H₂O₂, menadione, and juglone was associated with an increase in the activity of cellular catalase, superoxide dismutase, glucose-6-phosphate dehydrogenase, and glutathione reductase, the main enzymes involved in cell defense against oxidative stress.     

Nitric oxide alleviates manganese toxicity by preventing oxidative stress in excised rice leaves

In the present study, we have investigated the effects of nitric oxide (NO) on alleviating manganese (Mn)-induced oxidative stress in rice leaves. Exogenous MnCl₂ treatment to excised rice leaves for 24 and 48 h resulted in increased production of H₂O₂ and lipid peroxides, decline in the levels of antioxidants, glutathione and ascorbic acid, and increased activities of antioxidative enzymes, superoxide dismutase, guaiacol peroxidase, catalase, ascorbate peroxidase, dehydroascorbate reductase, and glutathione reductase. Treatment of rice leaves with 100 μM sodium nitroprusside (SNP), a NO donor, was effective in reducing Mn-induced increased levels of H₂O₂, lipid peroxides and increased activities of antioxidative enzymes. The levels of reduced ascorbate and glutathione were considerably recovered due to SNP treatment. The effect of SNP was reversed by the addition of NO scavenger, 2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (c-PTIO) suggesting that ameliorating effect of SNP is due to release of NO. The results indicate that MnCl₂ induces oxidative stress in excised rice leaves, lowers the levels of reduced ascorbate and glutathione, and elevates activities of the key antioxidative enzymes. NO appears to provide a protection to the rice leaves against Mn-induced oxidative stress and that exogenous NO application could be advantageous in combating the deleterious effects of Mn-toxicity in rice plants.     

Salinity induced oxidative stress and antioxidant system in salt-tolerant and salt-sensitive cultivars of rice (Oryza sativa L.)

Indices of oxidative stress viz., superoxide radical and H₂O₂ content increased in leaves of all the cultivars with the rise in salinity level, the increase was more pronounced and significant in salt-sensitive varieties and non-significant in resistant cultivars. Except for glutathione reductase (GR), basal activities of all other antioxidative enzymes viz. superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX) and glutathione reductase (GR) were significantly higher in leaves of all the resistant cultivars as compared to the sensitive ones. A differential response of salinity was observed on various enzymatic and non-enzymatic components of antioxidant system in leaves of salt-tolerant and salt-sensitive cultivars of rice (Oryza sativa L.). Activities of superoxide dismutase and glutathione reductase enhanced in all the tolerant cultivar while declined in the sensitive cultivars with increasing salinity from 0 to 100 mM. Salt-stress induced the activities of catalase and peroxidase in all the cultivars but the magnitude of increase was more pronounced in the sensitive cultivars than in the tolerant cultivars. Contrarily, APX activity increased in the salt-sensitive cultivars but showed no significant change in the salt-tolerant cultivars. The amount of ascorbic acid content, reduced glutathione (GSH), reduced/oxidized glutathione (GSSG) ratio was higher in leaves of the tolerant cultivars than that of the sensitive cultivars under saline conditions. It is inferred that leaves of salt-tolerant cultivars tend to attain greater capacity to perform reactions of antioxidative pathway under saline conditions to combat salinity-induced oxidative stress.     

Inactivation of red cell glutathione peroxidase by divicine and its relation to the hemolysis of favism

A significant inactivation of red blood cell glutathione peroxidase (25% less than the physiological value) was observed after exposure of intact erythrocytes to 2 mM divicine (an autoxidizable aminophenol from Vicia faba seeds) and 2 mM ascorbate for 3 h at 37°C. Addition of catalase and conversion of Hb to the carbomonoxy derivative resulted in protection against enzyme inactivation. Oxidation of Hb was a concurrent phenomenon, and augmented the inactivating effect. In hemolysates, much stronger effects were observed at shorter times (2 h); divicine was effective also without ascorbate, and the presence of reductants (ascorbate or glutathione or NADPH) enhanced its inactivating power. Of the other antioxidant enzymes, superoxide dismutase was unaffected under the same experimental conditions. Catalase was found to be much less sensitive to the inactivation; it was almost unaffected in experiments with intact erythrocytes and specifically protected by NADPH in experiments with hemolysates. This specific damage of glutathione peroxidase, apparently involving interaction of H₂O₂ and HbO₂, may be related to the pathogenesis of hemolysis in favism.     

Peroxide-metabolizing systems of the crystalline lens

The ability of transparent and cataractous human, rabbit and mice lenses to metabolize hydrogen peroxide in the surrounding medium was evaluated. Using a chemiluminescence method in a system of luminol-horseradish peroxidase and a photometric technique, the temperature-dependent kinetics of H₂O₂ decomposition by lenses were measured. The ability of opaque human lenses to catalyze the decomposition of 10^?4 M H₂O₂ was significantly decreased. However, this was reserved by the addition of GSH to the incubation medium. Incubation of the mice lenses with the initial concentration H₂O₂ 10^?4 M led to partial depletion of GSH in normal and cataractous lenses. Human cataractous lenses showed decreased activities of glutathione reductase, glutathione peroxidase (catalyzing reduction of organic hydroperoxides including hydroperoxides of lipids), superoxide dismutase, but no signs of depletion in activities of catalase or glutathione peroxidase (utilizing H₂O₂). The findings indicated an impairment in peroxide metabolism of the mature cataractous lenses compared to normal lenses to be resulted from a deficiency of GSH. An oxidative stress induced by accumulation of lipid peroxidation products in the lens membranes during cataract progression could be considered as a primary cause of GSH deficiency and disturbance of the redox balance in the lens.     

Effect of NaCl stress on H2O2 metabolism in rice leaves

The effect of NaCl stress on H₂O₂ metabolismin detached rice leaves was studied. NaCl (200 mM)treatment did not cause the accumulation ofH₂O₂ and resulted in no increase in lipidperoxidation and membrane leakage of leaf tissues. The activities of peroxidase, ascorbate peroxidase,superoxide dismutase, and glutathione reductase wereobserved to be greater in NaCl-stressed rice leavesthan in control leaves. However, glycolate oxidasewas lower in NaCl-treated rice leaves than in thecontrol leaves. There was no difference in catalaseactivity between NaCl and control treatments. Theseresults suggest that some antioxidant enzymes can beactivated in response to oxidative stress induced byNaCl.     

Role of glycolysis and antioxidant enzymes in the toxicity of amyloid beta peptide Aβ<Subscript>25–35</Subscript> to erythrocytes

The role of glycolysis and antioxidant enzymes in amyloid beta peptide Aβ_25–35 toxicity to human and rat erythrocytes was studied. The erythrotoxicity of Aβ_25–35 was shown to increase two-to fourfold both in the absence of glucose in the incubation medium and upon the addition of sodium fluoride, an enolase inhibitor. Potassium cyanide, a Cu,Zn-superoxide dismutase inhibitor, abolishes the toxic effect of Aβ_25–35 to erythrocytes, whereas mercaptosuccinate, a glutathione peroxidase inhibitor, and ouabain, a Na⁺,K⁺-ATPase inhibitor, promote it. Sodium azide, a catalase inhibitor, did not affect the cell lysis under the action of Aβ_25–35. The results support the hypothesis that H₂O₂, Cu,Zn superoxide dismutase, and glutathione peroxidase are involved in the toxicity mechanism rather than superoxide radical. Glycolysis and Na⁺,K⁺-ATPase play a substantial protective role. Fullerene C₆₀ nanoparticles are toxic to erythrocytes of both types; their toxicity is not related to enhanced oxidative stress and the mechanism of toxicity differs from that of Aβ_25–35.     

Pistacia lentiscus fruit oil reduces oxidative stress in human skin explants caused by hydrogen peroxide

We investigated the efficacy of Pistacia lentiscus fruit oil (PLFO) for protecting human skin from damage due to oxidative stress. PLFO contains natural antioxidants including polyphenols, sterols and tocopherols. We compared the antioxidant potential of PLFO with extra virgin olive oil (EVOO). Explants of healthy adult human skin were grown in culture with either PLFO or EVOO before adding hydrogen peroxide (H₂O₂). We also used cultured skin explants to investigate the effects of PLFO on lipid oxidation and depletion of endogenous antioxidant defense enzymes including glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT) one day after 2 h exposure to H₂O₂. We found that PLFO scavenged radicals and protected skin against oxidative injury. PLFO exhibited greater antioxidant and free radical scavenging activity than EVOO. Skin explants treated with PLFO inhibited H₂O₂ induced MDA formation by inhibition of lipid oxidation. In addition, the oil inhibited H₂O₂ induced depletion of antioxidant defense enzymes including GPx, SOD and CAT. We found that treatment with PLFO repaired skin damage owing to its antioxidant properties.     

An inductive pulse of hydrogen peroxide pretreatment restores redox-homeostasis and oxidative membrane damage under extremes of temperature in two rice cultivars

Imbibitional heat and chilling stress caused disruption of redox-homeostasis and oxidative damage to newly assembled membrane system by aggravating membrane lipid peroxidation and protein oxidation [measured in terms of thiobarbituric acid reactive substances (TBARS), free carbonyl content (C=O groups) and membrane protein thiol level (MPTL)] along with concomitant increase in accumulation of reactive oxygen species (superoxide and hydrogen peroxide) and significant reduction of antioxidative defense (assessed in terms of total thiol content and activities of superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase) in both the salt sensitive (Ratna) and resistant (SR 26B) germinating tissues of rice cultivars. When compared, salt resistant cultivar SR 26B found to suffer significantly less oxidative membrane damage as compared to salt sensitive cultivar Ratna. Treatment with low titer of hydrogen peroxide caused significant reversal in oxidative damages to the newly assembled membrane system imposed by imbibitional heat and chilling stress (evident from the data of TBARS, C=O, MPTL, ROS accumulation, membrane permeability status, membrane injury index and oxidative stress index) in seedlings of both the cultivars of rice (Ratna and SR 26B). Imbibitional H₂O₂ pretreatment also caused up-regulation of antioxidative defense (activities of superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase and total thiol content) in the heat and chilling stress-raised seedlings of experimental rice cultivars. When the parameters of early growth performances were assessed (in terms of relative growth index, biomass accumulation and vigor index), it clearly exhibited significant improvement of early growth performances of both the rice cultivars. Better response towards H₂O₂-mediated acclamatory performances and restoration of redox- homeostasis under extremes of temperature were noticed in salt sensitive rice cultivar Ratna compared to salt resistant SR 26B. Taken as a whole, the result suggests the significance of the role of ‘inductive pulse’ of H₂O₂ in acclimatizing adverse temperature stress by restoration of redox-homeostasis and mitigation of oxidative membrane protein and lipid damages during the recovery phase of post-germination event.     

Antioxidant Defenses in Wild Growing Halophyte Crithmum maritimum from Inland and Coastline Populations

Traditional Mediterranean diet includes the halophyte Crithmum maritimum L. (Apiaceae) which can be found in the coastline of the Balearic Islands but also inland. Both areas differed in the environmental conditions, mainly in salinity which can affect the oxidative status of this species. The aim was to evaluate the antioxidant enzyme activities, polyphenols and the lipid peroxidation in leaves of wild C. maritimum growing in a natural coastal area influenced by marine salinity and an inland area without marine influence. The activities of the antioxidant enzymes catalase, superoxide dismutase and glutathione peroxidase as well as polyphenol and reduced glutathione content were significantly higher in the samples from coastline population, whereas no significant differences were found in glutathione reductase activity and in malondialdehyde levels. The production of H₂O₂ was also significantly higher in the population from coastline. In conclusion, C. maritimum adapt their antioxidant defense machinery to the different salinity conditions, avoiding the instauration of oxidative stress.     

Erythrocyte antioxidants in aging and dementia

Age of patients and oxidative stress in brain cells may contribute to pathogenesis of Alzheimer’s disease (AD). Erythrocytes (red blood cells, RBC) are considered as passive “reporter cells” for the oxidative status of the whole body and remain poorly investigated in AD. The aim of this study was to assess whether the antioxidant status of RBC changes in aging and AD. Blood was taken from AD and non-Alzheimer’s dementia patients, aged-matched and younger controls. The antioxidant status of RBC was evaluated in each person participated in the study by measuring levels of H₂O₂, organic hydroperoxides, glutathione (GSH) and glutathione disulfide (GSSG), activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase, and glucose-6-phosphate dehydrogenase. In both aging and dementia, oxidative stress in RBC was shown to increase as evidenced by elevated concentrations of H₂O₂, organic hydroperoxides, decreased GSH/GSSG ratio, and decreased glutathione S-transferase activity. Decreased glutathione peroxidase activity in RBC may be considered as a new peripheral marker for Alzheimer’s disease while changes of other parameters of oxidative stress reflect age-related events.     

ANTIOXIDATIVE PROTECTION OF PERIDINIUM GATUNENSE IN LAKE KINNERET: SEASONAL AND DAILY VARIATION1

A comprehensive antioxidative mechanism was found in the freshwater dinoflagellate Peridinium gatunense Lemm. during the spring bloom in Lake Kinneret. Ascorbate was present throughout the bloom period and was responsible, together with catalase, for the elimination of photosynthetically produced H₂O₂. As glutathione concentrations and ascorbate regenerative enzymes were negligible during mid-spring, ascorbate was presumably biosynthesized during the photosynthetically active period. Antioxidative activity increased overall at the end of the spring in conjunction with elevated ambient stress conditions, for example high light. Under such circumstances, ascorbate was regenerated. Ascorbate levels doubled when cells were exposed to an increase in irradiance from 60 to 600 μmol photons·m^?2·s^?1, and on addition of H₂O₂, concentrations increased a further 20-fold. Significant antioxidative activity was also noted in the dark, although this was dependent on the presence of H₂O₂. Diurnal changes in antioxidants and their regenerative enzymes were observed. The activities of mono-dehydroascorbate reductase, glutathione reductase, and ascorbate concentrations showed ultraradian periodicity and were completely in phase throughout the day/night period. Dehydroascorbate reductase activity and glutathione concentrations were also in phase but showed aperiodic variation, as did ascorbate peroxidase activity. Superoxide dismutase and catalase activities were generally out of phase during the 24-h period but did show ultraradian periodicity. Lake samples entrained under constant light revealed an inate 12-h rhythm for catalase activity, during at least 36 h.