Amount Of Superoxide Radicals Research Articles

Protective responses of tolerant and sensitive wheat seedlings to systemic and local zearalenone application \u2013 Electron paramagnetic resonance studies

BackgroundMycotoxins are among the environmental stressors whose oxidative action is currently widely studied. The aim of this paper was to investigate the response of seedling leaves to zearalenone (ZEA) applied to the leaves (directly) and to the grains (indirectly) in tolerant and sensitive wheat cultivars.ResultsBiochemical analyses of antioxidant activity were performed for chloroplasts and showed a similar decrease in this activity irrespective of plant sensitivity and the way of ZEA application. On the other hand, higher amounts of superoxide radical (microscopic observations) were generated in the leaves of plants grown from the grains incubated in ZEA solution and in the sensitive cultivar. Electron paramagnetic resonance (EPR) studies showed that upon ZEA treatment greater numbers of Mn - aqua complexes were formed in the leaves of the tolerant wheat cultivar than in those of the sensitive one, whereas the degradation of Fe-protein complexes occurred independently of the cultivar sensitivity.ConclusionThe changes in the quantity of stable, organic radicals formed by stabilizing reactive oxygen species on biochemical macromolecules, indicated greater potential for their generation in leaf tissues subjected to foliar ZEA treatment. This suggested an important role of these radical species in protective mechanisms mainly against direct toxin action. The way the defense mechanisms were activated depended on the method of the toxin application.

Evaluation of angiogenic and neuroprotective potential of different extracts from three Veronica species

Methanol and 70% acetone extracts from Veronica jacquinii, Veronica urticifolia and Veronica teucrium were evaluated regarding their neuroprotective/antioxidant effects on the human neuroblastoma SH-SY5Y cell line. All extracts exhibited modest protective activity by increasing cell survival in cells stressed with sodium nitroprusside (9–12%) and hydrogen peroxide (16–21%) compared to non-treated cells. These activities were accompanied by reductions in the amount of superoxide radicals and index of lipid peroxidation. Extracts were further analysed for the content of total phenolics, phenylpropanoid glycosides and iridoids, and the major compounds acteoside and aucubin. The highest amount of total phenolics was observed in V. jacquinii, while V. teucrium was richest in total iridoids, acteoside and aucubin. Angiogenic properties on EA.hy926 human endothelial cells were also examined. At the highest non-toxic concentration (25 µg/ml), the tested extracts inhibited spontaneous tube formation of endothelial cells on the extracellular matrix, implying their possible antiangiogenic activity. The most potent inhibitory effects were shown by methanol extract of V. jacquinii and aqueous acetone extract of V. teucrium. The extracts did not significantly change the adhesive or migratory capacity of EA.hy926 cells. Considering the traditional use of Veronica species, these results suggest a need for further assessment of their supposed wound-healing properties.

Salicylic acid alleviates cold-induced photosynthesis inhibition andoxidative stress in Jasminum sambac

Salicylic acid (SA) is a signal molecule that mediates many biotic and abiotic stress-induced physiological responses in plants. In the current study the protective effects of SA on cold stress-caused oxidative damage and photosynthesis inhibition in jasmine plants (Jasminum sambac) were examined. Jasmine seedlings were pretreated with 100 µM SA for 3 days and then subjected to cold stress (4 °C) for 15 days. The amounts of superoxide radicals (O_2^{-}) and hydrogen peroxide (H_{2}O_{2}) significantly increased in leaves of plants exposed to cold stress and resulted in oxidative damage, indicated by an increase in malondialdehyde accumulation and membrane leakage. The total chlorophyll content, stomatal conductance (g_s), photochemical efficiency (F_v/F_m), and net photosynthesis rate (P_n) were significantly reduced in response to the cold treatment. However, plants pretreated with exogenous SA (100 µM) exhibited significantly higher photosynthesis-related parameters and antioxidant enzyme activities (peroxidase and catalase) and lower reactive oxygen species levels compared with the cold control. It was therefore concluded that SA could alleviate the cold treatment-caused oxidative stress and photosynthesis decline by enhancing the activities of antioxidant enzymes in leaves of jasmine.

Role of oxidative stress in chronic otitis media with effusion in children

Chronic otitis media with effusion (OME) is a common pathologic condition characterized by nonpurulent fluid in the middle ear (ME) that leads to moderate conductive hearing loss and flat tympanogram. During OME inflammatory cells generate large amounts of superoxide radicals to improve bactericidal activity. Overproduction of oxygen-derived free radicals induces oxidative damage in humans. Glutathione (GSH) is one of the major components of the antioxidant system that protects cells from oxidative stress. The aim of the study was to evaluate oxidative stress in chronic OME by investigation of ME fluids collected during myringotomy. During myringotomy, fluid was collected from the ME to evaluate lipid peroxide levels in the effusion. Immunohistochemical study was also performed to assess the anatomical features of tympanic membrane. Fifty-nine children with ME effusion without any resolution after repeated medical treatments were enrolled in the study. No morphological significant changes were observed. Lipid peroxide levels in all samples were high (mean 11.5 nmole/million cells), similar to the values found in other chronic diseases. GSH might be employed during surgery while applying ventilation tubes and after surgery to prevent oxidative stress. The high oxidant levels in chronic OME observed in our research and the improvement seen in children after antioxidant treatment suggest that oxygen-derived free radicals play an important role in chronic OME.

Phytocannabinoids tetrahydrocannabinol and cannabidiol act against rotenone induced damages in murine cell cultures

Phytocannabinoids (PCs) are terpenphenoles deriving from Cannabis species. In the brain, their activity is mediated by specific receptors such as the cannabinoid receptor 1 (CB1) or 2. These receptors are widely expressed in the brain. PCs as well have antioxidative capacities. Since one major event in PD is oxidative stress, cannabinoids are suggested as neuroprotective drugs. Oxidative stress can be induced by the complex I inhibitor rotenone. We investigated the effects of tetrahydrocannabinol (THC) and cannabidiol (CBD) on rotenone affected dissociated mesencephalic cultures and neuroblastoma cells (N18TG2) of mice. Cannabinoids (0.1 to 10µM) were administered alone or concomitantly with rotenone (80nM) for 48h. Rotenone treatment resulted in a degeneration of about 20% of the dopaminergic cells which was counteracted significantly by THC and CBD at 10µM. A significant restoration of glutathione levels in rotenone treated cultures at 0.1µM of THC and 10µM of CBD was also found. Electron spin resonance spectroscopy in N18TG2 cells revealed that the amount of superoxide radicals in cells exposed to rotenone nearly doubled. Neither THC nor CBD counteracted this increase. Thus radical scavenging does not appear to be the main mechanism of PCs action. The mechanisms which lead to the observed effects remain to be investigated, but cannabinoids might be candidates for neuroprotective agents in disorders linked to oxidative stress.

Oxidative stress in chronic otitis media with effusion

Conclusions: The high oxidant levels in chronic otitis media with effusion (OME) observed in our research and the improvement seen in children with chronic OME after antioxidant treatment suggest that oxygen-derived free radicals play an important role in chronic OME. Objectives: OME is a common pathologic condition characterized by nonpurulent fluid in the middle ear (ME) that leads to moderate conductive hearing loss and flat tympanogram. During OME inflammatory cells generate large amounts of superoxide radicals to improve bactericidal activity. Overproduction of oxygen-derived free radicals induces oxidative damage in humans. Glutathione (GSH) is one of the major components of the antioxidant system that protects cells from oxidative stress. The aim of the study was to evaluate oxidative stress in chronic OME by investigation of ME fluids collected during myringotomy. Methods: During myringotomy, fluid was collected from the ME to evaluate lipid peroxide levels in the effusion. Fifty-nine children with ME effusion without any resolution after repeated medical treatments were enrolled in the study. Results: Lipid peroxide levels in all samples were high (mean 11.5 nmole/million cells), similar to the values found in other chronic diseases. GSH might be employed during surgery while applying ventilation tubes and after surgery to prevent oxidative stress.

Aldosterone Causes DNA Strand Breaks and Chromosomal Damage in Renal Cells, Which are Prevented by Mineralocorticoid Receptor Antagonists

Epidemiological studies exploring the connection between hypertension and cancer incidence find a higher cancer mortality in hypertensive patients, particularly elevated in hypertension associated with a stimulation of the renin-angiotensin-aldosterone system. Primary aldosteronism, with plasma aldosterone levels between 0.5 and 1 nM (18-36 ng/dL) and local aldosterone levels up to 500 nM (18,000 ng/dL), is now recognised as a more common cause for hypertension. We recently found angiotensin II to be genotoxic due to its induction of oxidative stress. Since aldosterone in higher concentrations also has oxidative effects, its potential genotoxic action in pig LLC-PK1 cells with properties of proximal tubules was analysed. DNA damage was evaluated by two test systems: the comet assay, and the micronucleus frequency test. The results showed that aldosterone concentrations starting from 10 nM (360 ng/dL) caused a significant increase of DNA damage monitored with the comet assay in LLC-PK1, while there was no change in cell vitality and proliferation. The micronucleus frequency test revealed that 10 nM aldosterone also leads to the formation of micronuclei. Furthermore, the formation of superoxide radicals in the cells by this aldosterone concentration could be detected with the superoxide-specific stain dihydroethidium. Further evidence for oxidative stress-induced DNA damage was its reversibility by the antioxidants tempol and catalase. Addition of the steroidal mineralocorticoid receptor antagonist spironolactone or the novel selective nonsteroidal antagonist (R)-BR-4628 reduced the DNA damage and the amount of superoxide radicals indicating a receptor-dependent process.

Exogenous Salicylic Acid Alleviates Growth Inhibition and Oxidative Stress Induced by Hypoxia Stress in Malus robusta Rehd

Salicylic acid (SA) as a signal molecule mediates many biotic and environmental stress-induced physiologic responses in plants. In this study we investigated the role of SA in regulating growth and oxidative stress in Malus robusta Rehd under both normoxic and hypoxic conditions. Hypoxia stress inhibited plant growth and dramatically reduced biomass. Addition of SA significantly alleviated the plant growth inhibition. The amounts of superoxide radicals (O2 −) and hydrogen peroxide (H2O2) significantly increased in leaves of the plants exposed to hypoxia stress and resulted in oxidative stress, which was indicated by accumulated concentration of malondialdehyde (MDA) and electrolyte leakage. Addition of SA significantly decreased the level of O2 −, electrolyte leakage, and lipid peroxidation and enhanced the activities of superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX) under hypoxia stress. As important antioxidants, ascorbate (AsA) and glutathione (GSH) contents in the plant leaves were slightly increased by SA treatment compared to hypoxia stress treatment alone. It was concluded that SA could alleviate the detrimental effects of hypoxia stress on plant growth and of oxidative stress by enhancing the antioxidant defense system in leaves of M. robusta Rehd.

Dual Role of Superoxide Radicals in the Chilling-Induced photoinhibition in Maize Seedlings

Maize (Zea mays) seedlings were exposed for 6 h to strong irradiance (1 000 μmol m−1 s−1 of PPFD) at 5, 12, 17, or 25 °C, followed by an exposure to the darkness for 6 h at 22 °C. Leaf chlorophyll fluorescence, net photosynthetic rate (PN), and the amount of superoxide radicals (O2−⋅) in relation to chilling-induced photoinhibition were investigated. During the photophase, a good correlation (r=−0.879) was observed between ΦPS2 (relative quantum efficiency of PS2 electron transport) and the amount of O2−⋅. Treatment with exogenous O2−⋅ reduced the PN and ΦPS2 as the chilling stress did, that was inhibited by specific scavenger of O2−⋅. Hence chilling-induced photoinhibition might be due to the production of O2−⋅. In contrast, in the dark period, PN and ΦPS2 of the seedlings treated with the exogenous O2−⋅ were enhanced, but they were inhibited by the specific scavenger of O2−⋅, showing the photoprotective role of O2−⋅ in the recovery phase. Furthermore, in terms of the effect of exogenous O2−⋅ on the xanthophyll cycle, the O2−⋅ production suggested a promotion effect for the de-epoxidation of violaxanthin during the photophase, the epoxidation of zeaxanthin at the dark stage, and the increase of the xanthophyll pool both in the photophase and dark phase, resulting in an enhancement of the ability of non-photochemical quenching to avoid or alleviate the damage to photosynthetic apparatus.

Effect of manganese chloride exposure on liver and brain mitochondria function in rats

Manganese (Mn) is an essential trace element found in many enzymes. As is the case for many essential trace elements, excessive Mn is toxic. Individuals suffering from manganese toxicity exhibit several symptoms, which are similar to those frequently observed in cases of Parkinson's disease. In this investigation, we studied the effect of manganese chloride (7.5, 15.0, and 30.0 mg/kg body weight) on mitochondrial function and attempted to ascertain the mechanism of manganese-induced mitochondrial dysfunction. The production of reactive oxygen species in mitochondria of rat liver and brain was assayed using 2′,7′-dichlorofluorescin diacetate, and the activities of respiratory chain enzymes were examined spectrophotometrically. Monoamine oxidase (MAO) activity was assayed by measuring reduction of benzylamine. Manganese and calcium content in mitochondria were determined by atomic absorption spectrophotometry. These results indicate that manganese chloride (MnCl 2) can decrease MAO activity and inhibit the respiratory chain. Manganese can accumulate in mitochondria and inhibit efflux of calcium. There is a significant inverse correlation between the amount of superoxide radicals and the specific activities of the mitochondria enzymes. Mitochondrial function was significantly affected in both males and females.

V-Ha-Ras overexpression induces superoxide production and alters levels of primary antioxidant enzymes.

Reactive oxygen species have been shown to play important roles in v-Ha-Ras mitogenic signaling. We hypothesized that v-Ha-Ras overexpression would induce superoxide production, and therefore modify expression of the primary antioxidant enzyme system. We have demonstrated that immortal rat kidney epithelial cells stably transduced with constitutively active v-Ha-ras produced significantly larger amounts of superoxide radical than wild-type or vector-transfected control cells. The levels of the primary antioxidant enzymes copper- and zinc-containing superoxide dismutase, manganese-containing superoxide dismutase, catalase, and glutathione peroxidase were increased in the superoxide-overproducing cells. DNA-binding activities of the transcription factors activator protein-1, activator protein-2, and nuclear factor-kappaB were all enhanced in the superoxide-overproducing cells. These v-Ha-ras transduced cells also had a shortened cell doubling time and higher plating efficiency, and displayed greater constitutive levels of phosphorylated mitogen-activated protein kinases. These data demonstrate that v-Ha-Ras overexpression increases superoxide production and this apparently affects a wide variety of cell signaling and redox systems.