Concerted Action Of Reduced Glutathione And Superoxide Dismutase In Preventing Redox Cycling Of Dihydroxypyrimidines, And Their Role In Antioxidant Defence

Dialuric Acid, the reduced form of the β-cell toxin alloxan, and the related fava bean derivatives divicine and isouramil, autoxidize rapidly in neutral solution by a radical mechanism. GSH promotes redox cycling of each compound, with concomitant GSH oxidation and H₂O₂ production. With superoxide dismutase present, there is a lag period in which little oxidation occurs, followed by rapid oxidation. GSH extends this lag and decreases the subsequent rate of oxidation, so that with superoxide dismutase and a sufficient excess of GSH. coupled oxidation of GSH and each pyrimidine is almost completely suppressed. This mechanism may be a means whereby GSH in combination with superoxide dismutase protects against the cytotoxic effects of these reactive pyrimidines. Superoxide dismutase may also protect cells against oxida-tive stress in other situations where GSH acts as a radical scavenger. and we propose that the concerted action of GSH and superoxide dismutase constitutes an important antioxidant defence     

Concerted Action Of Reduced Glutathione And Superoxide Dismutase In Preventing Redox Cycling Of Dihydroxypyrimidines,And Their Role In Antioxidant Defence

Dialuric Acid, the reduced form of the β-cell toxin alloxan, and the related fava bean derivatives divicine and isouramil, autoxidize rapidly in neutral solution by a radical mechanism. GSH promotes redox cycling of each compound, with concomitant GSH oxidation and H₂O₂ production. With superoxide dismutase present, there is a lag period in which little oxidation occurs, followed by rapid oxidation. GSH extends this lag and decreases the subsequent rate of oxidation, so that with superoxide dismutase and a sufficient excess of GSH. coupled oxidation of GSH and each pyrimidine is almost completely suppressed. This mechanism may be a means whereby GSH in combination with superoxide dismutase protects against the cytotoxic effects of these reactive pyrimidines. Superoxide dismutase may also protect cells against oxida-tive stress in other situations where GSH acts as a radical scavenger. and we propose that the concerted action of GSH and superoxide dismutase constitutes an important antioxidant defence     

谷胱甘肽还原酶和超氧化物歧化酶在玉米幼苗热激诱导的交叉适应中的作用

玉米幼苗经过热激处理后,在随后的高温、低温、干旱和盐胁迫环境中,其存活率明显高于未热激的幼苗,表明热激能提高植物的抗热性、抗冷性、抗旱性和抗盐性,证实了玉米幼苗交叉适应现象的存在;热激还可提高谷胱甘肽还原酶(GR)和超氧化物歧化酶(SOD)的活性,且在上述4种胁迫过程中GR、SOD活性水平与玉米幼苗的存活率呈正相关,表明GR和SOD参与玉米幼苗交叉适应的形成.     

The pyrogallol assay for superoxide dismutase: Absence of a glutathione artifact

Reduced glutathione was found to affect the assay for superoxide dismutase when autooxidation of epinephrine, but not pyrogallol, was used as the indicator. Glutathione concentrations in the micromolar range, which correspond to levels in erythrocyte extracts, were capable of perturbing the epinephrine assay method and causing overestimation of enzyme content. The pyrogallol method was not significantly affected by large excesses of glutathione and appears to be a superior method for tissue extracts likely to be rich in glutathione.     

Hepatic response to the oxidative stress induced by E. coli endotoxin: Glutathione as an index of the acute phase during the endotoxic shock

Reactive oxygen species are important mediators of cellular damage during endotoxic shock. In order to investigate the hepatic response to the oxidative stress induced by endotoxin, hepatic and plasma glutathione (total, GSH and GSSG), GSSG/GSH ratio as well as Mn-superoxide dismutase and catalase activities were determined during the acute and recovery phases of reversible endotoxic shock in the rat. A significant increase in liver and plasma total glutathione content was observed 5 h after endotoxin treatment (acute phase), followed by a diminution of these parameters below control values at 48 h (recovery phase). The significant increases of GSSG levels and GSSG/GSH ratio are indicative of oxidative stress occurring during the acute phase. Liver Mn-SOD activity showed a similar time dependency as the GSSG/GSH ratio; however, a marked decrease in the liver catalase activity was observed during the process. These results indicate the participation of liver glutathione in the response to endotoxin and the possible use of plasma glutathione levels and GSSG/GSH ratio as indicators of the acute phase during the endotoxic process. (Mol Cell Biochem 159: 115-121, 1996)     

Doxorubicin Resistance Conferred by Selective Enhancement of Intracellular Glutathione Peroxidase or Superoxide Dismutase Content in Human MCF-7 Breast Cancer Cells

To examine the role of doxorubicin-stimulated oxyradical formation in tumor cell killing, we introduced glutathione peroxidase (GSH Px) or superoxide dismutase (SOD) into MCF-7 cells by “scrape loading.” Control cytoplasmic GSH Px and SOD levels increased from (mean ± S.E.) 0.37nmol/min/mg and 0.58 μg SOD/mg, respectively, to 3.99 or 7.63 nmol/min/mg and 1.40 or 1.83 μg SOD/mg after treatment with either 150 or 300 units/ml of GSH Px or 20 or 40mg/ml SOD. Resistance to doxorubicin was cbrrelated with the level of GSH Px introduced into the MCF-7 cells: a one-hour exposure to 1.75 μM doxorubicin decreased the cloning efficiency of control cells loaded with medium alone to 34%, whereas doxorubicin-treated cells augmented with 150 or 300 units/ml of GSH Px had plating efficiencies of 56 or 86%, P < 0.05. Introduction of SOD increased MCF-7 resistance to doxorubicin similarly. The heat-inactivated enzymes were not protective. Cells loaded with GSH Px were also resistant to the redox cycling anticancer quinone mitomycin C but not to the redox inactive analogs 5-iminodaunorubicin and mitoxan-trone. suggesting that amplification of GSH Px or SOD levels can produce doxorubicin resistance in MCF-7 cells.     

The antioxidant defense system of isolated guinea pig Leydig cells

Utilization of highly enriched preparations of steroidogenic Leydig cells have proven invaluable for studying the direct effects of various hormones and agents on Leydig cell functionin vitro. However, recent work indicates that isolated Leydig cells are often subjected to oxygen (O₂) toxicity when cultured at ambient (19%) oxygen concentrations. Because intracellular antioxidants play an important role in protecting cells against oxygen toxicity, we have investigated the intracellular antioxidant defense system of isolated Leydig cells. The cellular levels of several antioxidants including catalase, glucose-6-phosphate dehydrogenase (G-6-PDH), superoxide dismutase (SOD) of the Cu/Zn & Mn variety, glutathione peroxidase, glutathione reductase and total glutathione were quantitated using enriched populations of Leydig cells isolated from adult male guinea pig testes. Compared to whole testicular homogenates, Leydig cells contained significantly (P<0.01) less G-6-PDH, total SOD, glutathione reductase and total glutathione, but significantly (P<0.001) more glutathione peroxidase. Compared to hepatic values previously reported in the guinea pig, Leydig cells contain nearly 400 times less catalase, about 14 times less glutathione peroxidase and almost 11 times less glutathione reductase. Since G-6-PDH and glutathione reductase are both necessary to regenerate reduced gluthathione (GSH) which couples with glutathione peroxidase to breakdown hydrogen peroxide (H₂O₂) under normal conditions, it is plausible that the oxygen toxicity observed in isolated Leydig cells is due to the intracellular accumulation of H₂O₂. Using the dichlorofluorescin diacetate (DCF-DA) assay, we found that Leydig cells incubated in the presence of 19% O₂ produced significantly (P<0.001) higher levels of H₂O₂ with time in culture compared to Leydig cells maintained at 3% O₂. These results support the hypothesis that the increased susceptibility of isolated Leydig cells to oxygen toxicity may be due, in part, to decreased amounts of certain antioxidant defenses and an increased production of the reactive oxygen species H₂O₂.     

Mechanism of citrinin-induced dysfunction of mitochondria. V. Effect on the homeostasis of the reactive oxygen species

The effects of citrinin in the maintenance of the homeostasis of the reactive oxygen species in rat liver cells were evaluated. Citrinin (CTN) modifies the antioxidant enzymatic defences of cells through the inhibition of GSSG-reductase and transhydrogenase. No effect was observed on GSH-peroxidase, catalase, glucose 6-phosphate and 6 phosphogluconate dehydrogenases, and superoxide dismutase. The mycotoxin increased the generation of reactive oxygen species, stimulating the production of the superoxide anion in the respiratory chain. The results suggest that oxidative stress is an important mechanism, side by side with other effects previously shown, in the establishment of the cytotoxicity and cellular death provoked by CTN in several tissues. © 1997 John Wiley & Sons, Ltd.     

The Effect of Extremely Low‐Frequency Electromagnetic Fields on the Prevalence of Musculoskeletal Disorders and the Role of Oxidative Stress

Extremely low‐frequency electromagnetic fields (ELF‐EMFs) may cause negative health effects. This study aimed to investigate the direct and indirect effects of chronic exposure to extremely low‐frequency electric and magnetic fields on the prevalence of musculoskeletal disorders (MSDs). In this cross‐sectional study, 152 power plant workers were enrolled. The exposure level of employees was measured based on the IEEE Std C95.3.1 standard. Superoxide dismutase (SOD), catalase (Cat), glutathione peroxidase (GPx), total antioxidant capacity (TAC), and malondialdehyde (MDA) (independent variables) were measured in the serum of subjects. The Nordic musculoskeletal questionnaire was used to assess MSDs (dependent variable). The mean exposure of electric and magnetic fields were 4.09 V/m (standard deviation [SD] = 4.08) and 16.27 µT (SD = 22.99), respectively. Increased levels of SOD, Cat, GPx, and MDA had a direct significant relation with MSDs. In the logistic regression model, SOD (odds ratio [OR] = 0.952, P = 0.026), GPx (OR = 0.991, P = 0.048), and MDA (OR = 0.741, P = 0.021) were significant predictors of MSDs. ELF‐EMFs were not related to MSDs directly; however, increased levels of oxidative stress may cause MSDs. Bioelectromagnetics. 2019;40:354–360. © 2019 Bioelectromagnetics Society.     

The effects of diazinon on lipid peroxidation and antioxidant enzymes in rat heart and ameliorating role of vitamin E and vitamin C

Diazinon is one of the most widely used organophosphate insecticides (OPIs) in agriculture and public health programs. Reactive oxygen species (ROS) caused by OPIs may be involved in the toxicity of various pesticides. The aim of this study was to investigate how diazinon affects lipid peroxidation (LPO) and the antioxidant defense system in vivo and the possible ameliorating role of vitamins E and C. For this purpose, experiments were done to study the effects of DI on LPO and the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) in adult rat heart. Experimental groups were: (1) control group, (2) diazinon treated (DI) group, (3) DI+vitamins E and C-treated (DI+Vit) group. The levels of malondialdehyde (MDA) and the activities of SOD and CAT increased significantly in the DI group compared with the control group. The activity of SOD and the levels of MDA decreased significantly in the DI+Vit group compared with the DI group. The differences between the DI+Vit and control groups according to the MDA levels and the activities of both SOD and CAT were statistically significant. These results suggest that treating rats with a single dose of diazinon increases LPO and some antioxidant enzyme activities in the rat myocardium and, in addition, that single-dose treatment with a combination of vitamins E and C after the administration of diazinon can reduce LPO caused by diazinon, though this treatment was not sufficiently effective to reduce the values to those in control group.     

The influence of alimentary microelementosis on the activity of superoxide dismutase and glutathione peroxidase

Studies of K_m for glutathione peroxidase (GPx) and activities of superoxide dismutase and GPx were carried out in liver and erythrocytes of rats kept on either the normal semisynthetic diet or a high-fat diet with increased content of Cu, Zn, Mn, and Se. The diet containing microelement additions caused the increase in TBH affinity of liver and erythrocyte GPx, as well as the decrease of liver SOD observed on the 14th day of the treatment of rats with the high-fat diet with additional increase of Cu, Zn, Mn, and Se.     

The effect of negative air ions on the respiratory organs and blood

The effect of ionized air containing negatively charged ions at a concentration of 320000–350000 ions/cm³ inhaled by rats was studied. It was demonstrated that the inhalation of negative air ions for 60 min activated the secretion of goblet cells without impairing the tracheal mucosa and changing the protein profile of bronchoalveolar lavage. It was also found that the level of spontaneous production of reactive oxygen species by unfractionated blood cells increased after the action of negative air ions in both males and females. However, the intensity of their generation induced by opsonized zymosan increased only in females. Different sensitivities of the female and male blood antioxidant enzymes—superoxide dismutase and glutathione reductase—to negative air ions were observed. These results allow the effect of negative air ions on the respiratory organs and blood to be interpreted as priming and weak activation via a direct action on the mucosa of primary target respiratory organs and then on the blood.     

粪产碱菌（Alcaligenes faecalis）对稻根氧化还原特性及水稻多元酚和内根际激素水平的影响

联合固氮粪产碱菌结合于水稻根表时能增强水稻根部还原力和稻根超氧化物歧化酶（ＳＯＤ）活性。实验室和田间试验证明粪产碱菌能提高水稻幼苗对高、低温不良环境的抗逆性。经浸种处理的水稻幼苗植株内多元酚含量增加了１２．５％。粪产以菌对接种水稻多元酚抽提物有强烈的趋化性,而该抽提物对粪产碱菌的固氮活性有明显的刺激作用。多元酚抽提物经双向纸层析和薄层层析表明接种诱导了至少一个特征组分含量提高。采用粪产减菌野生型Ａ１５０１（ｎｉｆ＋）和固氮缺陷型Ａ１５０６（Ｎｉｆ－）浸种能改变宿主水稻内源激素水平,提高内根际的ＩＡＡ和Ｚ的含量,促进植株及根系的生长发育,使其侧根和根毛数目明显增多。在根际联合体系形成过程中,多元酚或激素可能充当植物与细菌间相互作用的一类特异信号分子。     

Effect of lead exposure on liver lipid peroxidative and antioxidant defense systems of protein-undernourished rats

The effect of the liver mitogen, lead nitrate [Pb(NO₃)₂], on protein-undernutrition-induced increased lipid peroxidation and reduced antioxidants levels was investigated in rats. Animals were divided into four groups: A, B, C, and D of five animals each. Animals in groups C and D were placed on a low-protein diet (5% casein) and animals in groups A and B were maintained on a normal diet (16% casein) for 14 wk and fed ad libitum. Animals in groups B and D were each given a single intravenous injection of Pb(NO₃)₂ (100 μmol/kg body weight) 72 h before sacrifice. The results confirm that protein undernutrition (PU) induced an increase in lipid peroxidation with concomitant reductions in catalase (CAT) activity, glutathione (GSH) level, and superoxide dismutase (SOD) activity. Lead (Pb) treatment, however, provoked increased lipid peroxidation, CAT activity, and GSH level but resulted in reduced SOD activity in both normal and PU-rats. These results suggest that Pb exacerbates liver lipid peroxidation in PU rats and suggests the involvement of free radicals in the pathogenesis of Pb poisoning. In addition, the results show that Pb affects well-fed and PU rats in similar ways but that the CAT activity of PU rats is more sensitive to the effect of Pb than that of normal rats.     

茉莉酸甲酯对水分胁迫下花生幼苗SOD活性和膜脂过氧化作用的影响

茉莉酸甲酯能减缓水分胁迫时期花生幼苗（三叶期）叶片相对合水量的降低,明显提高抗旱性。经过茉莉酸甲酯处理的花生幼苗,在水分胁迫条件下,体内超氧物歧化酶和过氧化氢酶的活性下降程度比未经处理的轻,超氧物歧化酶同工酸酶带数则较多,抗坏血酸含量也较高,以减少雨二醛在叶片中的积累。     

谷胱甘肽对顺铂致小鼠染色体畸变的保护作用

为了研究谷胱甘Lk．（GSH）对顺铂（cDDP）所致染色体畸变的影响,将昆明小鼠随机分为空白对照组、GSH组、CDDP组、GSH＋CDDP组进行实验,GSH组按照1200mg／（kg·d1连续3天尾静脉注射GSH,对照组注射等量生理盐水;CDDP组于第2天一次注射顺铂20mg/ｋg。对小鼠尾静脉取血检测血常规,处死小鼠,取骨髓进行有核细胞计数、微核实验和染色体G显带,双盲阅片并进行统计学分析。结果表叽对照组细胞染色体数目与形态完好,微核出现的机率极低。GSH组与空白对照组相比无显著差异（Ｐ〉0．05）。CDDP组、GSH＋CDDP组出现了明显的骨髓抑制现象,染色体畸变率及微核率显著增高,与空白对照组比较均有显著性差异（Ｐ〈0．01）。GSH＋CDDP组与CDDP组相比染色体畸变率明显下降（Ｐ〈0．05）。表明谷胱甘肽对顺铂所致的染色体损伤具有一定的保护作用。     

尖顶羊肚菌对急性酒精性胃黏膜损伤保护作用研究

研究尖顶羊肚菌菌丝体水提液对酒精引起的大鼠急性胃黏膜损伤的保护作用。以95%乙醇诱导的大鼠胃黏膜损伤为模型,测定各组胃黏膜损伤指数,并测定胃黏膜超氧化物歧化酶（SOD）、丙二醛（MDA）、谷胱甘肽（GSH）含量,采用幽门结扎法,测定大鼠胃酸、胃蛋白酶与胃黏液分泌的量。结果表明羊肚菌中、高剂量能明显降低胃黏膜损伤指数（p＜0.05）;羊肚菌不能抑制胃酸的分泌（p＞0.05）,但是能增加胃蛋白酶与胃黏液的分泌（p＜0.05）;95%乙醇能引起胃黏膜SOD活性与GSH的降低,MDA含量的增加,给予羊肚菌能明显抑制这一现象。结果说明羊肚菌对急性酒精性胃黏膜损伤的保护作用是与增加胃黏液分泌与提高机体抗氧化能力有关。     

The Activity of the Antioxidative System in Cadmium-Treated Arabidopsis thaliana

Changes in the content of reactive oxygen species (ROS) and activity of the antioxidant system were measured in leaves of Arabidopsis thaliana (L.) Heynh exposed to Cd²⁺. Mature plants growing in the nutrient solution were treated with Cd²⁺ at different concentrations (0, 5, 25, 50, 100 μM). An increase of content in leaves was observed at 5, 25 and 50 μM Cd²⁺. A strong accumulation of H₂O₂ was found only at the lowest Cd²⁺ concentration. The content of OH^*. was high at 50 and 100 μM Cd²⁺. Superoxide dismutase (SOD) activity was always higher in Cd²⁺-treated plants than in control. Catalase (CAT) activity decreased with increasing Cd²⁺ concentration in the nutrient solution. Guaiacol peroxidase (POX) activity was particularly high at the lowest and highest Cd²⁺ concentrations and ascorbate peroxidase (APX) activity additionally at 50 μM Cd²⁺. Enhanced activity of monodehydroascorbate reductase (MDHAR) and strong reduction in ascorbate (AA) content were observed at 25 μM Cd²⁺. Glutathione reductase (GR) activity was always higher than in control but decreased as Cd²⁺ concentration increased. However, it was accompanied by gradual content increase of SH-groups. This revised version was published online in July 2006 with corrections to the Cover Date.     

The Effect of Phosphinothricin (Glufosinate) on Glutathione Synthesis in Plants

The inhibitory effect of DL-phosphinothricin (glufosinate) on glutathione synthesis was studied in vivo and in vitro. The influence of phosphinothricin on γ-glutamylcysteine synthetase was compared with the already known effects of l -buthionine sulfoximine and l -methionine sulfoximine. The results showed that phosphinothricin and buthionine sulfoximine are inhibitors of γ-glutamylcysteine synthetase of plants. With both substances the enzyme was inhibited by 50 % at a concentration of 7 . 10^?4M (pI₅₀ = 3.15). Methionine sulfoximine reduced the enzyme activity by 50% at 5 . 10^?2 M (pI₅₀ = 1.30). It is discussed that the target enzyme of phosphinothricin is the glutamine synthetase whereas the γ-glutamylcysteine synthetase is only an accessory target.     

The oxidant defense system in human neuroblastoma IMR-32 cells predifferentiation and postdifferentiation to neuronal phenotypes

Differentiated neurons were investigated for their susceptibility to oxidative damage based on variations in the oxidant defense system occurring during differentiation. The main antioxidant enzymes and substances in human neuroblastoma (IMR-32) cells were evaluated pre- and post-differentiation to a neuronal phenotype. The activity of CuZn superoxide dismutase (CuZnSOD) and Mn superoxide dismutase (MnSOD) and the concentration of CuZnSOD were higher, but the activity and concentration of catalase were lower after differentiation. Differentiated cells had higher activity of glutathione peroxidase (GPx), lower concentration of total glutathione, a higher ratio of oxidised/reduced glutathione and lower activity of glucose-6-phosphate dehydrogenase than undifferentiated cells. We conclude that differentiated neuronal cells may be highly susceptible to oxidant-mediated damage based on the relative activities of the main antioxidant enzymes and on a limited capacity to synthesise and/or recycle glutathione.