Optimization of extraction and development of an LC-HRMS method to quantify glutathione and glutathione disulfide in white wine lees and yeast derivatives

The antioxidant capacity of wine depends on its quality and aging potential. Aging on lees can improve this capacity thanks to the release of glutathione (GSH), as can the addition of yeast derivatives (YD). Therefore, the GSH potential of wine lees (WL) and YD requires investigation. We propose an optimized method to extract and quantify GSH from WL and YD. First, a method was developed to detect and quantify GSH and glutathione disulfide (GSSG) using LC-HRMS. Second, Box-Behnken response surface methodologies (RSM) were applied to both matrices. Results showed that the main parameter affecting GSH extraction efficiency was ethanol concentration. Quantitation of various samples revealed GSH concentrations of up to 900 µg/g for WL and 40 mg/g for YD. To our knowledge, the absolute quantitation of GSH/GSSG in these matrices has not been reported until now.

[Metabolic Stress of Red Blood Cells Induces Hemoglobin Glutathionylation]

Metabolic stress caused by a lack of glucose significantly affects the state of red blood cells, where glycolysis is the main pathway for the production of ATP. Hypoglycemia can be both physiological (occurring during fasting and heavy physical exertion) and pathological (accompanying a number of diseases, such as diabetes mellitus). In this study, we have characterized the state of isolated erythrocytes under metabolic stress caused by the absence of glucose. It was established that 24 h of incubation of the erythrocytes in a glucose-free medium to simulate blood plasma led to a two-fold decrease in the ATP level into them. The cell size, as well as intracellular sodium concentration increased. These findings could be the result of a disruption in ion transporter functioning because of a decrease in the ATP level. The calcium level remained unchanged. With a lack of glucose in the medium of isolated erythrocytes, there was no increase in ROS and a significant change in the level of nitric oxide, while the level of the main low-molecular weight thiol of cells, glutathione (GSH) decreased by almost 2 times. It was found that the metabolic stress of isolated red blood cells induced hemoglobin glutathionylation despite the absence of ROS growth. The cause was the lack of ATP, which led to a decrease in the level of GSH because of the inhibition of its synthesis and, probably, due to a decrease in the NADPH level required for glutathione (GSSG) reduction and protein deglutathionylation. Thus, erythrocyte metabolic stress induced hemoglobin glutathionylation, which is not associated with an increase in ROS. This may have an important physiological significance, since glutathionylation of hemoglobin changes its affinity for oxygen.

Biomarkers for the toxicity of sublethal concentrations of triclosan to the early life stages of carps

Accumulation, contents of protein, non-enzymatic antioxidant glutathione (GSH and GSSG), lipid peroxidation product (melondialdehyde-MDA) and organic acids (fumarate, succinate, malate and citrate), and activities of neurological (acetylcholinesterase-AChE), detoxification (glutathione S-transferase-GST) and metabolic (lactate dehydrogenase-LDH, aspartate transaminase-AST and alanine transaminase-ALT) enzymes were recorded in the hatchlings of Cyprinus carpio, Ctenopharyngodon idella, Labeo rohita and Cirrhinus mrigala after 7 and 14 days exposure and 10 days post exposure (recovery period) to sublethal concentrations (0.005, 0.01, 0.02 and 0.05 mg/L) of triclosan, a highly toxic and persistent biocide used in personal care products. Accumulation was maximum between 7-14 days at 0.01 mg/L for C. carpio and L. rohita but at 0.005 mg/L for C. idella and C. mrigala. No triclosan was observed at 0.005 mg/L in C. carpio and C. mrigala after recovery. Significant decline in protein, glutathione and acetylcholinesterase but increase in glutathione S-transferase, lactate dehydrogenase, aspartate transaminase, alanine transaminase, melondialdehyde and organic acids over control during exposure continued till the end of recovery period. Integrated biomarker response (IBR) analysis depicted higher star plot area for glutathione and glutathione S-transferase during initial 7 days of exposure, thereafter, during 7-14 days of exposure and the recovery period, higher star plot area was observed for acetylcholinesterase, aspartate transaminase, alanine transaminase and organic acids. Higher star plot area was observed for protein in all the species throughout the study. The study shows that L. rohita is most sensitive and glutathione, acetylcholinesterase, aspartate transaminase and alanine transaminase are the biomarkers for the toxicity of sublethal concentrations of TCS.

Adrenergic regulation during acute hepatic infection with Entamoeba histolytica in the hamster: involvement of oxidative stress, Nrf2 and NF-KappaB

Oxidative stress and transcriptional pathways of nuclear factor erythroid 2-related factor 2 (Nrf2) and nuclear factor kappa-B (NF-κB) are critically involved in the etiopathology of amebic liver abscess (ALA). In this work, we studied the relationship between the adrenergic nervous system and ALA in the hamster. ALA was visible at 12 h of infection. While 6-hydroxidopamine (6-OHDA) decreased infection, propranolol (β-adrenergic blocker) treatment was associated with less extensive liver damage, and phentolamine treatment (α-adrenergic blocker) significantly reduced ALA compared to 6-OHDA and propranolol. Serum enzymatic activities of alanine aminotransferase (ALT) and γ-glutamyl transpeptidase (γ-GTP) were increased at 12 h post-infection. Chemical denervation and α and β-adrenergic blockers decreased ALT to normal levels, while 6-OHDA and propranolol showed a trend to decrease γ-GTP but phentolamine significantly reduced γ-GTP. Amebic infection increased oxidized glutathione (GSSG) and decreased both reduced glutathione (GSH) and the GSH/GSSG ratio. Propranolol and 6-OHDA showed a tendency to decrease GSSG. However, GSH, GSSG and GSH/GSSG returned to normal levels with phentolamine. Furthermore, amebic infection increased pNF-κB and interleukin-1β (IL-1β), and showed a tendency to decrease hemoxigenase-1 (HO-1), but not Nrf2. Chemical denervation showed a trend to decrease pNF-κB and IL-1β, and neither Nrf2 nor HO-1 increased significantly. In addition, NF-κB and IL-1β were attenuated by propranolol and phentolamine treatments, although phentolamine showed significant overexpression of Nrf2 and HO-1. This suggests that the adrenergic system may be involved in oxidative stress and in modulation of the Nrf2 and NF-κB pathways during ALA development.

Assessment of glutathione/glutathione disulphide ratio and S-glutathionylated proteins in human blood, solid tissues, and cultured cells

Glutathione (GSH) is the major non-protein thiol in humans and other mammals, which is present in millimolar concentrations within cells, but at much lower concentrations in the blood plasma. GSH and GSH-related enzymes act both to prevent oxidative damage and to detoxify electrophiles. Under oxidative stress, two GSH molecules become linked by a disulphide bridge to form glutathione disulphide (GSSG). Therefore, assessment of the GSH/GSSG ratio may provide an estimation of cellular redox metabolism. Current evidence resulting from studies in human blood, solid tissues, and cultured cells suggests that GSH also plays a prominent role in protein redox regulation via S -glutathionylation, i.e., the conjugation of GSH to reactive protein cysteine residues. A number of methodologies that enable quantitative analysis of GSH/GSSG ratio and S-glutathionylated proteins (PSSG), as well as identification and visualization of PSSG in tissue sections or cultured cells are currently available. Here, we have considered the main methodologies applied for GSH, GSSG and PSSG detection in biological samples. This review paper provides an up-to-date critical overview of the application of the most relevant analytical, morphological, and proteomics approaches to detect and analyse GSH, GSSG and PSSG in mammalian samples as well as discusses their current limitations.

UHPLC-MS/MS determination of varietal thiol precursors in Sauvignon Blanc grapes

Varietal thiol precursors in grapes are subject to metabolic changes during post-harvest treatments. Metabolic activity should therefore be limited after sampling to understand their biosynthesis in the berry and genetic regulation. In this study, berries were frozen in liquid nitrogen immediately after harvesting, transported in dry ice, stored briefly at -80 °C, cryo-milled and extracted without being thawed in cold methanol in a ratio of 1:4 (w/v). A UHPLC-MS/MS method for quantitative determination of the thiol precursors 3-S-glutathionylhexan-1-ol (G3MH), 3-S-cysteinylhexan-1-ol (Cys3MH), 4-S-glutathionyl-4-methylpentan-2-one (G4MMP) and 4-S-cysteinyl-4-methylpentan-2-one (Cys4MMP), glutathione, oxidized glutathione and L-methionine in grapes was developed. Reference material was provided through synthesis of precursors and their deuterium labelled analogues. The average thiol precursor content in grapes in 2013-15 was in the range 8-16 μg kg-1 for G3MH, 1-6 μg kg-1 for Cys3MH, 1-4 μg kg-1 for Cys4MMP and 0.3 μg kg-1 for G4MMP. In 2013 and 2014, the highest precursor content in mature Sauvignon Blanc grapes from vineyards located in Italy regarded G3MH, followed by Cys3MH, Cys4MMP and G4MMP. In 2015, G3MH was again the most abundant precursor, but followed by Cys4MMP, Cys3MH and G4MMP.

Biochemical and Ultrastructural Lung Damage Induced by Rhabdomyolysis in the Rat

Rhabdomyolysis-induced oxidative stress is associated with morphological and functional damage to the kidney and other organs, but applications of this model in the lung are still lacking. The aim of the present study was to determine the relationship between oxidative stress and the morphological changes occurring in the lungs of rats subjected to rhabdomyolysis. Rhabdomyolysis was induced by intramuscular glycerol injection (50% v/v, 10 ml/kg), and the control group was injected with saline vehicle. Arterial blood samples were drawn at 0, 2, 4, and 6 hrs for measurement of arterial gases, creatine kinase activity, and plasma free F2-isoprostane levels. Six hours later, the lungs were removed to determine the wet-to-dry weight ratio, reduced glutathione (GSH) and GSH disulfide (GSSG) levels, and activity of antioxidant enzymes (cataiase [CAT], superoxide dismutase [SOD], and GSH peroxidase [GSH-Px]). Protein carbonylation and lipid peroxidation were assessed in the lungs by measurement of carbonyl and malondialdehyde (MDA) production, respectively. Bronchoalveolar lavage, cell counts, and lung ultrastructural studies were also performed. Six hours after glycerol injection, arterial PO2 and PCO2 were 23% and 38% lower, respectively, and plasma free F2-isoprostane levels were 72% higher, compared with control values. In lungs, protein carbonyl and MDA production were 58% and 12% higher, respectively; the GSH:GSSG ratio and GSH-Px activity were 43% and 60% lower, respectively; and activities of CAT and SOD showed no significant differences compared with controls. Rhabdomyolysis-induced ultrastructural impairment of the lung showed Type II cell damage, extracytoplasmic lamellar bodies and lack of tubular myelin reorganization, endothelial cellular edema, and no disruption of the alveolar-capillary barrier. These results provide evidence that rhabdomyolysis could induce tissue injury associated with increased oxidative stress, suggesting the contribution of oxidative stress to the pathogenic mechanism of acute lung injury.

In vitro evaluation of antitumoral efficacy of catalase in combination with traditional chemotherapeutic drugs against human lung adenocarcinoma cells

Lung cancer is the most lethal cancer-related disease worldwide. Since survival rates remain poor, there is an urgent need for more effective therapies that could increase the overall survival of lung cancer patients. Lung tumors exhibit increased levels of oxidative markers with altered levels of antioxidant defenses, and previous studies demonstrated that the overexpression of the antioxidant enzyme catalase (CAT) might control tumor proliferation and aggressiveness. Herein, we evaluated the effect of CAT treatment on the sensitivity of A549 human lung adenocarcinoma cells toward various anticancer treatments, aiming to establish the best drug combination for further therapeutic management of this disease. Exponentially growing A549 cells were treated with CAT alone or in combination with chemotherapeutic drugs (cisplatin, 5-fluorouracil, paclitaxel, daunorubicin, and hydroxyurea). CalcuSyn(®) software was used to assess CAT/drug interactions (synergism or antagonism). Growth inhibition, NFκB activation status, and redox parameters were also evaluated in CAT-treated A549 cells. CAT treatment caused a cytostatic effect, decreased NFκB activation, and modulated the redox parameters evaluated. CAT treatment exhibited a synergistic effect among most of the anticancer drugs tested, which is significantly correlated with an increased H2O2 production. Moreover, CAT combination caused an antagonism in paclitaxel anticancer effect. These data suggest that combining CAT (or CAT analogs) with traditional chemotherapeutic drugs, especially cisplatin, is a promising therapeutic strategy for the treatment of lung cancer.

Pitfalls in the analysis of the physiological antioxidant glutathione (GSH) and its disulfide (GSSG) in biological samples: An elephant in the room

Glutathione (GSH) is the most abundant low-molecular-mass thiol within cells and one of the major antioxidant compounds in body fluids. Under pro-oxidant conditions, two GSH molecules donate one electron each and are converted into glutathione disulfide (GSSG). The GSH/GSSG molar ratio is considered a powerful index of oxidative stress and disease risk. Despite high interest in GSH/GSSG titration as measures of thiol redox balance, no broad agreement has yet been reached as to the best pre-analytical and analytical methods for the quantitation of these molecules in biological samples. Consequently, measured concentrations of GSH and GSSG and calculated GSH/GSSG molar ratios vary widely among laboratories. Here, we describe in detail the main analytical and pre-analytical problems related to the artificial oxidation of the sulfhydryl (SH) group of GSH that occur during sample manipulation. We underline how this aspect has been neglected for long time after its first description more than fifty years ago. Finally, selected reliable procedures and methods to measure GSH and GSSG in biological samples are discussed.

Straightforward method to quantify GSH, GSSG, GRP, and hydroxycinnamic acids in wines by UPLC-MRM-MS

A novel, robust and fast ultrahigh performance liquid chromatography–multiple reaction monitoring mass spectrometry method has been developed for the simultaneous quantification of reduced glutathione (GSH), oxidized glutathione (GSSG), grape reaction product (GRP) and hydroxycinnamic acids in wine. The method was evaluated in terms of linearity, precision, accuracy, limits of detection and quantification, stability and matrix effects. Quantitative recovery (74–110%) and satisfactory interday precision (RSD <14%) were achieved for all target compounds. No significant matrix-dependent suppression/enhancement effects were observed. To demonstrate the method applicability, white, rosé and red wine samples with different levels of oxidation were analyzed. Levels of GSH and GSSG varied from 1.63 to 9.91 mg/L and from 0.32 to 3.33 mg/L, respectively. Levels of caftaric acid ranged from 2.57 to 293.07 mg/L. Levels of GRP were between 28.35 and 114.20 mg/L.

Heritability of glutathione and related metabolites in stored red blood cells

Red blood cells (RBCs) collected for transfusion deteriorate during storage. This deterioration is termed the "RBC storage lesion." There is increasing concern over the safety, therapeutic efficacy, and toxicity of transfusing longer-stored units of blood. The severity of the RBC storage lesion is dependent on storage time and varies markedly between individuals. Oxidative damage is considered a significant factor in the development of the RBC storage lesion. In this study, the variability during storage and heritability of antioxidants and metabolites central to RBC integrity and function were investigated. In a classic twin study, we determined the heritability of glutathione (GSH), glutathione disulfide (GSSG), the status of the GSSG,2H(+)/2GSH couple (Ehc), and total glutathione (tGSH) in donated RBCs over 56 days of storage. Intracellular GSH and GSSG concentrations both decrease during storage (median net loss of 0.52 ± 0.63 mM (median ± SD) and 0.032 ± 0.107 mM, respectively, over 42 days). Taking into account the decline in pH, Ehc became more positive (oxidized) during storage (median net increase of 35 ± 16 mV). In our study population heritability estimates for GSH, GSSG, tGSH, and Ehc measured over 56 days of storage are 79, 60, 67, and, 75%, respectively. We conclude that susceptibility of stored RBCs to oxidative injury due to variations in the GSH redox buffer is highly variable among individual donors and strongly heritable. Identifying the genes that regulate the storage-related changes in this redox buffer could lead to the development of new methods to minimize the RBC storage lesion.

An application of RP-HPLC for determination of the activity of cystathionine β-synthase and γ-cystathionase in tissue homogenates

The RP-HPLC-based method of determination of the activity of cystathionine β-synthase and γ-cystathionase was undertaken in mouse liver, kidney and brain. Products of the reactions, such as cystathionine, α-ketobutyrate, cysteine and glutathione, were measured using the RP-HPLC method. A difference in the cystathionine level between homogenates with totally CTH-inhibiting concentrations of DL-propargylglycine and without the inhibitor was employed to evaluate the activity of cystathionine β-synthase. Gamma-cystathionase activity was measured using DL-homoserine as a substrate and a sensitive HPLC-based assay to measure α-ketobutyrate. The results confirmed high cystathionine β-synthase activity and no γ-cystathionase activity in brain, and high γ-cystathionase activity in mouse liver. The method presented here allows for evaluating the relative contribution of CBS and CTH to generation of H2S in tissues. Additionally, it provides results, which reflect the redox status (GSH/GSSG) of a tissue.

Multiparametric protocol for the determination of thiol redox state in living matter

Thiol redox state (TRS) evaluation is mostly restricted to the estimation of GSH and GSSG. However, these TRS parameters can estimate the GSSG/GSH potential, which might be useful for indicating abnormalities in redox metabolism. Nonetheless, evaluation of the multiparameric nature of TRS is required for a more accurate assessment of its physiological role. The present protocol extends the partial assessment of TRS by current methodologies. It measures 15 key parameters of TRS by two modular subprotocols: one for the glutathione (GSH)- and cysteine (CSH)-based nonprotein (NP) thiols/mixed disulfides (i.e., GSH, GSSG, GSSNP, CSH, CSSNP, NPSH, NPSSNP, NP(x)SH(NPSSNP), NP(x)SH(NPSH)), and the other for their protein (P) thiols/mixed disulfides (i.e., PSH, PSSG, PSSC, PSSNP, PSSP, NP(x)SH(PSSNP)). The protocol eliminates autoxidation of GSH and CSH (and thus overestimation of GSSG and CSSNP). Its modularity allows the determination GSH and GSSG also by other published specific assays. The protocol uses three assays; two are based on the photometric reagents 4,4'-dithiopyridine (DTP) and ninhydrin (NHD), and the third on the fluorometric reagent o-phthaldialdehyde (OPT). The initial assays employing these reagents have been extensively modified and redesigned for increased specificity, sensitivity, and simplicity. TRS parameter values and their standard errors are estimated automatically by sets of Excel-adapted algebraic equations. Protocol sensitivity for NPSH, PSH, NPSSNP, PSSP, PSSNP, CSH, CSSNP, PSSC, NP(x)SH(NPSSNP), and NP(x)SH(NPSH) is 1 nmol -SH/CSH, for GSSNP 0.2 nmol, for GSH and GSSG 0.4 nmol, and for PSSG 0.6 nmol. The protocol was applied on human plasma, a sample of high clinical value, and can be also applied in any organism.

The concentration of glutathione in human erythrocytes is a heritable trait

Glutathione (GSH) is a ubiquitous, redox-active, small molecule that is critical to cellular and organism health. In red blood cells (RBCs), the influence of the environment (e.g., diet and lifestyle) on GSH levels has been demonstrated in numerous studies. However, it remains unknown if levels of GSH are determined principally by environmental factors or if there is a genetic component, i.e., heritability. To investigate this we conducted a twin study. Twin studies are performed by comparing the similarity in phenotypes between mono- and dizygotic twin pairs. We determined the heritability of GSH, as well as its oxidation product glutathione disulfide (GSSG), the sum of GSH equivalents (tGSH), and the status of the GSSG/2GSH couple (marker of oxidation status, Ehc) in RBCs. In our study population we found that the estimated heritability for the intracellular concentration of GSH in RBCs was 57 %; for GSSG it was 51 %, tGSH 63 %, and Ehc 70 %. We conclude that a major portion of the phenotype of these traits is controlled genetically. We anticipate that these heritabilities will also be reflected in other cell types. The discovery that genetics plays a major role in the innate levels of redox-active species in RBCs is paradigm shifting and opens new avenues of research in the field of redox biology. Inherited RBC antioxidant levels may be important disease modifiers. By identifying the relative contributions of genes and the environment to antioxidant variation between individuals, new therapeutic strategies can be developed. Understanding the genetic determinants of these inherited traits may allow personalized approaches to relevant therapies.

Role of endoplasmic reticulum stress in aberrant activation of fluoride-treated osteoblasts

The aberrant activation of osteoblasts in the early stage is one of the critical steps during the pathogenesis of skeletal fluorosis. The endoplasmic reticulum (ER) stresses and unfolded protein response (UPR) are initiated to alleviate the accumulation of unfolded proteins against cell injury. The previous researches had demonstrated that fluoride induced ER stress in other cells or tissues. In this study, we determined the ER stress and UPR to investigate their roles in aberrant activation of fluoride-treated osteoblasts. The gene expression of bone markers and UPR factors in MC3T3-E1 cells treated with varying doses of fluoride administration was analyzed. Meantime, levels of glutathione and glutathione disulfide were tested by the ultraperformance liquid chromatography-tandem mass spectrometry applications. Our results indicated that a certain dose and period of fluoride administration induced cell proliferation and differentiation, and Runx2 was involved in the regulation of osteoblastic differentiation of MC3T3-E1 cells. Increase trend of Runx2 expression was consistent with change of marker of ER stress. Fluoride caused ER stress and stimulated UPR during the process of osteoblast maturation, while oxidative stress was also active in the occurrence of ER stress. These data indicated that ER stress and UPR were possibly involved in the action of fluoride on osteoblasts.

Effect of beta-carotene on oxidative stress and expression of cardiac connexin 43

BACKGROUND

Intervention studies have shown an increased mortality in patients who received beta-carotene. However, the mechanisms involved in this phenomenon are still unknown.

OBJECTIVE

Evaluate the influence of beta-carotene on oxidative stress and the expression of connexin 43 in rat hearts.

METHODS

Wistar rats, weighing approximately 100 g, were allocated in two groups: CONTROL GROUP (n=30), that received the diet routinely used in our laboratory, and Beta-Carotene Group (n = 28), which received beta-carotene (in crystal form, added and mixed to the diet) at a dose of 500 mg of beta-carotene/kg of diet. The animals received the treatment until they reached 200-250 g, when they were sacrificed. Samples of blood, liver and heart were collected to perform Western blotting and immunohistochemistry for connexin 43; morphometric studies, dosages of beta-carotene by high-performance liquid chromatography as well as reduced glutathione, oxidized glutathione and lipids hydroperoxides were performed by biochemical analysis.

RESULTS

Beta-carotene was detected only in the liver of Beta-Carotene Group animals (288 ± 94.7 µg/kg). Levels of reduced/oxidized glutathione were higher in the liver and heart of Beta-Carotene Group animals (liver -

CONTROL GROUP

42.60 ± 1.62; liver - Beta-Carotene Group: 57.40 ± 5.90; p = 0.04; heart: -

CONTROL GROUP

117.40 ± 1.01; heart - Beta-Carotene Group: 121.81 ± 1.32 nmol/mg protein; p = 0.03). The content of total connexin 43 was larger in Beta-Carotene Group.

CONCLUSION

Beta-carotene demonstrated a positive effect, characterized by the increase of intercellular communication and improvement of anti-oxidizing defense system. In this model, mechanism does not explain the increased mortality rate observed with the beta-carotene supplementation in clinical studies.

Diesel exhaust particles induce cysteine oxidation and s-glutathionylation in house dust mite induced murine asthma

Background

Diesel exhaust particle (DEP) exposure enhances allergic inflammation and has been linked to the incidence of asthma. Oxidative stress on the thiol molecules cysteine (Cys) and glutathione (GSH) can promote inflammatory host responses. The effect of DEP on the thiol oxidation/reduction (redox) state in the asthmatic lung is unknown.

Objective

To determine if DEP exposure alters the Cys or GSH redox state in the asthmatic airway.

Methods

Bronchoalveolar lavage fluid was obtained from a house dust mite (HDM) induced murine asthma model exposed to DEP. GSH, glutathione disulfide (GSSG), Cys, cystine (CySS), and s-glutathionylated cysteine (CySSG) were determined by high pressure liquid chromatography.

Results

DEP co-administered with HDM, but not DEP or HDM alone, decreased total Cys, increased CySS, and increased CySSG without significantly altering GSH or GSSG.

Conclusions

DEP exposure promotes oxidation and S-glutathionylation of cysteine amino acids in the asthmatic airway, suggesting a novel mechanism by which DEP may enhance allergic inflammatory responses.

Detection and quantification of S-nitrosoglutathione (GSNO) in pepper (Capsicum annuum L.) plant organs by LC-ES/MS

Glutathione (GSH) is one of the major, soluble, low molecular weight antioxidants, as well as the major non-protein thiol in plant cells. However, the relevance of this molecule could be even greater considering that it can react with nitric oxide (NO) to generate S-nitrosoglutathione (GSNO) which is considered to function as a mobile reservoir of NO bioactivity in plants. Although this NO-derived molecule has an increased physiological and phytopathological relevance in plants cells, its identification and quantification in plant tissues have not be reported so far. Using liquid chromatography-electrospray/mass spectrometry (LC-ES/MS), a method was set up to detect and quantify simultaneously GSNO as well reduced and oxidized glutathione (GSH and GSSG, respectively) in different pepper plant organs including roots, stems and leaves, and in Arabidopsis leaves. The analysis of NO and GSNO reductase (GSNOR) activity in these pepper organs showed that the content of GSNO was directly related to the content of NO in each organ and oppositely related to the GSNOR activity. This approach opens up new analytical possibilities to understand the relevance of GSNO in plant cells under physiological and stress conditions.

Association between life-span extension by caloric restriction and thiol redox state in two different strains of mice

The hypothesis that the life-extending effect of caloric restriction (CR) is associated with an attenuation of the age-related pro-oxidant shift in the thiol redox state was tested employing a novel experimental design. Amounts of GSH, GSSG, and protein mixed disulfides (Pr-SSG) in the skeletal muscle and liver were compared between two strains of mice that have similar life spans when fed ad libitum (AL), but different life spans under the standard CR regimen. The life span of one strain, C57BL/6, is extended under CR, whereas it remains unaffected in the other strain, DBA/2. Mice were fed AL or 40% less food starting at 4 months and compared at 6 and 24 months of age. The amounts of GSSG and Pr-SSG increased and the GSH:GSSG ratios decreased with age in both strains of AL-fed mice. CR prevented these age-related changes in the C57BL/6, whose life span is extended by CR, but not in the DBA/2 mice, in which it remains unaffected. CR enhanced the activity of glutamate-cysteine ligase in the C57BL/6, but not in the DBA/2 mice. The results suggest that longevity extension by CR may be associated with the attenuation of age-related pro-oxidizing shifts in the thiol redox state.

Interaction between 24-hydroxycholesterol, oxidative stress, and amyloid-β in amplifying neuronal damage in Alzheimer's disease: three partners in crime

All three cholesterol oxidation products implicated thus far in the pathogenesis of Alzheimer's disease, 7β-hydroxycholesterol, 24-hydroxycholesterol, and 27-hydroxycholesterol, markedly enhance the binding of amyloid-beta (Aβ) to human differentiated neuronal cell lines (SK-N-BE and NT-2) by up-regulating net expression and synthesis of CD36 and β1-integrin receptors. However, only 24-hydroxycholesterol markedly potentiates the pro-apoptotic and pro-necrogenic effects of Aβ(1-42) peptide on these cells: 7β-hydroxycholesterol and 27-hydroxycholesterol, like unoxidized cholesterol, show no potentiating effect. This peculiar behavior of 24-hydroxycholesterol at physiologic concentrations (1 μm) depends on its strong enhancement of the intracellular generation of NADPH oxidase-dependent reactive oxygen species (ROS), mainly H(2) O(2) , and the consequent impairment of neuronal cell redox equilibrium, measured in terms of the GSSG/GSH ratio. Cell incubation with antioxidants quercetin or genistein prevents 24-hydroxycholesterol's pro-oxidant effect and potentiation of Aβ-induced necrosis and apoptosis. Thus, the presence of 24-hydroxycholesterol in the close vicinity of amyloid plaques appears to enhance the adhesion of large amounts of Aβ to the plasma membrane of neurons and then to amplify the neurotoxic action of Aβ by locally increasing ROS steady-state levels. This report further supports a primary involvement of altered brain cholesterol metabolism in the complex pathogenesis of Alzheimer's disease.

Exercise training attenuates oxidative stress and decreases p53 protein content in skeletal muscle of type 2 diabetic Goto-Kakizaki rats

Oxidative stress can impair mitochondrial function and fuel utilization and is closely linked with the development of insulin resistance in skeletal muscle in diabetes mellitus as well as fatty liver disease. In vitro data indicate that cellular levels of reactive oxygen species depend on the expression and activity of p53, which plays a key role in energy metabolism and as a crucial transcription factor for SCO cytochrome oxidase deficient homolog 2 (SCO2) and tumor p53-induced glycolysis and apoptosis regulator (TIGAR), which regulate mitochondrial respiration and glycolysis in cells. The aims of this study were: (1) to investigate whether exercise training could attenuate the development of oxidative stress in skeletal muscle in rats with diabetes mellitus (DM) and (2) to evaluate the potential role of p53 and its transcriptional targets in exercise-induced mitochondrial adaptation in skeletal muscle in rats with DM. Goto-Kakizaki (GK) rats, which develop type 2 DM (T2DM) early in life, were randomly divided into two groups: (1) subjected to regular exercise on a treadmill at 20m/min for 30-60min, 6 days per week for 8 weeks (GK exercising, n=7), and (2) rested controls (GK control, n=7). Exercise training increased serum adiponectin and decreased serum insulin and levels of glycosylated hemoglobin (P<0.05). Skeletal muscle GSH content and GSH:GSSG ratio increased in GK exercising rats vs GK controls (P<0.05). Skeletal muscle COX activity (P<0.05), mtDNA markers (P<0.01), and COXII protein levels (P<0.05) increased in response to exercise training. Exercise training decreased p53 protein levels and TIGAR expression in skeletal muscle (P<0.05), but SCO2 expression was unchanged. These data indicate that exercise training can attenuate oxidative stress and increase mitochondrial DNA content in skeletal muscle in rats with T2DM and that exercise-induced suppression of p53 and TIGAR expression may play a role in preventing oxidative stress in insulin resistance.

Pro-oxidant activity of apocynin radical

Apocynin has been widely used as an NADPH oxidase inhibitor in many experimental models. However, concern regarding the efficacy, selectivity, and oxidative side effects of the inhibitor is increasing. In this study, our aim was to characterize the pro-oxidant properties of apocynin and the structurally-related compounds vanillin and vanillic acid. Glutathione (GSH), cysteine, ovalbumin, and the coenzyme NADPH were chosen as potential target biomolecules that could be affected by transient free radicals from apocynin, vanillin and vanillic acid. Additionally, trolox and rifampicin were used as models of hydroquinone moieties, which are particularly susceptible to oxidation. Transient radicals were generated by horseradish peroxidase/hydrogen peroxide-mediated oxidation. In the presence of apocynin, oxidation of GSH was increased seven-fold, and the product of this reaction was identified as GSSG. Similar results were obtained for oxidation of cysteine and ovalbumin. Oxidation of the coenzyme NADPH increased more than 100-fold in the presence of apocynin. Apocynin also caused rapid oxidation of trolox and rifampicin to their quinone derivatives. In conclusion, the pro-oxidant activity of apocynin is related to its previous oxidation leading to transient free radicals. This characteristic may underlie some of the recent findings regarding beneficial or deleterious effects of the phytochemical.

Altered lipid profile, oxidative status and hepatitis B virus interactions in human hepatocellular carcinoma

Altered membrane integrity in hepatocellular carcinoma (HCC) tissue was indicated by an elevation in cholesterol and significant decrease in phosphatidylcholine (PC). The resultant decreased phosphatidylcholine/phosphatidylethanolamine (PC/PE) and increased cholesterol/phospholipid ratios are associated with decreased fluidity in the carcinoma tissue. The lower PC was associated with a decrease in the quantitative levels of the saturated (C16:0, C18:0), omega6 (C18:2, C20:4) and omega3 (C22:5, C22:6) fatty acids (FAs), resulting in reduced long-chain polyunsaturated fatty acids (LCPUFAs), total PUFA and an increase in omega6/omega3 FA ratio. In PE, the saturated and omega3 (C22:5, C22:6) FAs were reduced while the total omega6 FA level was not affected, leading to an increased omega6/omega3 FA ratio. Increased levels of C18:1omega9, C20:2omega6 and reduction of 22:6omega3 in PC and PE suggest a dysfunctional delta-6 desaturase. The reduced PC/PE ratio resulted in a decreased C20:4omega6 (PC/PE) ratio, implying a shift towards synthesis of the 2-series eicosanoids. Lipid peroxidation was reduced in both hepatitis B negative (HBV(-)) and positive (HBV(+)) HCC tissues. Glutathione (GSH) was decreased in HCC while HBV had no effect, suggesting an impairment of the GSH redox cycle. In contrast HBV infection enhanced GSH in the surrounding tissue possibly to counter oxidative stress as indicated by the increased level of conjugated dienes. Apart from the reduced LCPUFA, the low level of lipid peroxidation in the carcinoma tissue was associated with increased superoxide dismutase and glutathione peroxidase activity. The disruption of the redox balance, resulting in increased cellular antioxidant capacity, could create an environment for resistance to oxidative stress in the carcinoma tissue. Alterations in membrane cholesterol, phospholipids, FA parameters, C20:4omega6 membrane distribution and low lipid peroxidation are likely to be important determinants underlying the selective growth advantage of HCC cells.

Rapid capillary electrophoresis analysis of glutathione and glutathione disulfide in roots and shoots of plants exposed to copper

INTRODUCTION

Glutathione and glutathione disulfide can be determined by capillary zone electrophoresis; however, the frequent use of acidic precipitation of protein from samples prior to analysis generates an acidic matrix of strength and pH that may cause changes in the method sensitivity, comigration of species or changes in the equilibria that relate both species in cells or fluids.

OBJECTIVE

To optimise electrophoretic conditions for glutathione and glutathione disulfide determination, and to improve pre-analytical treatment for better visualization of the signals of both peptides in an acidic matrix.

METHODOLOGY

The method consisted of direct photometric detection at 185 nm and 300 mm borate at pH 7.6 as background electrolyte. The variables under study were voltage applied, injection time, capillary length and electrolyte pH. Seedlings were hydroponically grown and the peptides were extracted with metaphosphoric acid.

RESULTS

The resulting acidic matrix was previously treated with the same background electrolyte to prevent comigration and to improve signal resolution. The optimised method showed good reproducibility and linearity, with correlation coefficients above 0.999 and detection limits below 3 microM, and determination of both analytes in less than 3 min. Analyte recovery in the process was in the 88-104% range. The concentration range found in hydroponically grown tomato plants, irrespective of copper level, was 45-100 nmol/g fresh weight for glutathione and below 56 nmol/g fresh weight for glutathione disulfide.

CONCLUSION

The results obtained here support the applicability of the method to the fast and simultaneous determination of glutathione and glutathione disulfide in tissue of shoots and roots of plants grown under either normal or stressful conditions.

Impact of food disinfection on beneficial biothiol contents in strawberry

In this study, the impact of four food disinfectants including hydrogen peroxide, free chlorine, and gaseous- and aqueous-phase ozone with industrial doses on the concentration of biothiol compounds gamma-glutamylcysteinylglycine (GSH) and cystein (CYS) in strawberry was investigated for 1, 5, 15, 30, and 60 or 120 min. Additionally, the amount of oxidized glutathione (GSSG) was analyzed for calculation of the GSH/GSSG ratio as an indicator of oxidative stress. After this treatment, thiol contents of strawberry samples were examined using high-performance liquid chromatography (HPLC) technique. According to the results of measurements, free chlorine treatment for only 60 min significantly decreased CYS content in strawberry (p < 0.05). A significant decline in the GSH/GSSG ratio was also observed when H2O2 was applied for all time intervals except for 1 min (p < 0.05). However, aqueous-phase ozone treatment did not significantly affect the thiol levels (p < 0.05). In conclusion, this study may provide optimum disinfection methods for strawberry to minimize loss of beneficial biothiols.

Oxidative stress in duckweed (Lemna minor L.) caused by short-term cadmium exposure

The mechanisms of plant defence against cadmium toxicity have been studied by short-term exposure of Lemna minor L. (common duckweed) to concentrations of CdCl2 ranging from 0 to 500microM. High accumulation of cadmium was observed (12,320+/-2155microgg(-1) at 500microM CdCl2), which caused a gradual decrease of plant growth, increased lipid peroxidation, and weakened the entire antioxidative defence. Total glutathione concentration decreased significantly; however, the concentration of oxidized glutathione remained stable. The responses of four antioxidant enzymes showed that catalase was the most inhibited after CdCl2 exposure, ascorbate peroxidase and guaiacol peroxidase moderately, and glutathione reductase least. The total antioxidative potential revealed an induced antioxidative network at 0.1microM CdCl2 (137+/-13.2% of the control) and its reduction to only 47.4+/-4.0% of the control at higher cadmium concentrations. The possible application of the examined biomarkers in ecotoxicological research is discussed.

Proline modulates the intracellular redox environment and protects mammalian cells against oxidative stress

The potential of proline to suppress reactive oxygen species (ROS) and apoptosis in mammalian cells was tested by manipulating intracellular proline levels exogenously and endogenously by overexpression of proline metabolic enzymes. Proline was observed to protect cells against H(2)O(2), tert-butyl hydroperoxide, and a carcinogenic oxidative stress inducer but was not effective against superoxide generators such as menadione. Oxidative stress protection by proline requires the secondary amine of the pyrrolidine ring and involves preservation of the glutathione redox environment. Overexpression of proline dehydrogenase (PRODH), a mitochondrial flavoenzyme that oxidizes proline, resulted in 6-fold lower intracellular proline content and decreased cell survival relative to control cells. Cells overexpressing PRODH were rescued by pipecolate, an analog that mimics the antioxidant properties of proline, and by tetrahydro-2-furoic acid, a specific inhibitor of PRODH. In contrast, overexpression of the proline biosynthetic enzymes Delta(1)-pyrroline-5-carboxylate (P5C) synthetase (P5CS) and P5C reductase (P5CR) resulted in 2-fold higher proline content, significantly lower ROS levels, and increased cell survival relative to control cells. In different mammalian cell lines exposed to physiological H(2)O(2) levels, increased endogenous P5CS and P5CR expression was observed, indicating that upregulation of proline biosynthesis is an oxidative stress response.

Determination of cellular redox status by stable isotope dilution liquid chromatography/mass spectrometry analysis of glutathione and glutathione disulfide

Oxidation of glutathione (GSH) to glutathione disulfide (GSSG) occurs during cellular oxidative stress. The redox potential of the 2GSH/GSSG couple, which is determined by the Nernst equation, provides a means to assess cellular redox status. It is difficult to accurately quantify GSH and GSSG due to the ease with which GSH is oxidized to GSSG during sample preparation. To overcome this problem, a stable isotope dilution liquid chromatography/multiple reaction monitoring mass spectrometry (LC/MRM-MS) method has been developed using 4-fluoro-7-sulfamoylbenzofurazan (ABD-F) derivatization. ABD-F derivatization of the GSH thiol group was rapid, quantitative, and occurred at room temperature. The LC/MRM-MS method, which requires no sample clean-up, was validated within the calibration ranges of 5 to 400 nmol/mL in cell lysates for GSH and 0.5 to 40 nmol/mL in cell lysates for GSSG. Calibration curves prepared by adding known concentrations of GSH and GSSG to cell lysates were parallel to the standard curve prepared in buffers. GSH and GSSG concentrations were determined in two monocyte/macrophage RAW 267.4 cell lines with or without 15-LOX-1 expression (R15LO and RMock cells, respectively) after treatment with the bifunctional electrophile 4-oxo-2(E)-nonenal (ONE). R15LO cells synthesized much higher concentrations of the lipid hydroperoxide, 15(S)-hydroperoxyeicosatetraenoic acid (15-HPETE), which undergoes homolytic decomposition to ONE. GSH was depleted by ONE treatment in both RMock and R15LO cells, leading to significant increases in their redox potentials. However, R15LO cells had higher GSH concentrations (most likely through increased GSH biosynthesis) and had increased resistance to ONE-mediated GSH depletion than RMock cells. Consequently, R15LO cells had lower reduction potentials at all concentrations of ONE. GSSG concentrations were higher in R15LO cells after ONE treatment when compared with the ONE-treated RMock cells. This suggests that increased expression of 15(S)-HPETE modulates the activity of cellular GSH reductases or the transporters involved in removal of GSSG.

Assay for quantitative determination of glutathione and glutathione disulfide levels using enzymatic recycling method

The spectrophotometric/microplate reader assay method for glutathione (GSH) involves oxidation of GSH by the sulfhydryl reagent 5,5'-dithio-bis(2-nitrobenzoic acid) (DTNB) to form the yellow derivative 5'-thio-2-nitrobenzoic acid (TNB), measurable at 412 nm. The glutathione disulfide (GSSG) formed can be recycled to GSH by glutathione reductase in the presence of NADPH. The assay is composed of two parts: the preparation of cell cytosolic/tissue extracts and the detection of total glutathione (GSH and GSSG). The method is simple, convenient, sensitive and accurate. The lowest detection for GSH and GSSG is 0.103 nM in a 96-well plate. This method is rapid and the whole procedure takes no longer than 15 min including reagent preparation. The method can assay GSH in whole blood, plasma, serum, lung lavage fluid, cerebrospinal fluid, urine, tissues and cell extracts and can be extended for drug discovery/pharmacology and toxicology protocols to study the effects of drugs and toxic compounds on glutathione metabolism.

Melatonin administration prevents cardiac and diaphragmatic mitochondrial oxidative damage in senescence-accelerated mice

Cardiac and diaphragmatic mitochondria from male SAMP8 (senescent) and SAMR1 (resistant) mice of 5 or 10 months of age were studied. Levels of lipid peroxidation (LPO), glutathione (GSH), GSH disulfide (GSSG), and GSH peroxidase and GSH reductase (GRd) activities were measured. In addition, the effect of chronic treatment with the antioxidant melatonin from 1 to 10 months of age was evaluated. Cardiac and diaphragmatic mitochondria show an age-dependent increase in LPO levels and a reduction in GSH:GSSG ratios. Chronic treatment with melatonin counteracted the age-dependent LPO increase and GSH:GSSG ratio reduction in these mitochondria. Melatonin also increased GRd activity, an effect that may account for the maintenance of the mitochondrial GSH pool. Total mitochondrial content of GSH increased after melatonin treatment. In general, the effects of age and melatonin treatment were similar in senescence-resistant mice (SAMR1) and SAMP8 cardiac and diaphragmatic mitochondria, suggesting that these mice strains display similar mitochondrial oxidative damage at the age of 10 months. The results also support the efficacy of long-term melatonin treatment in preventing the age-dependent mitochondrial oxidative stress.

Neurotoxic Potential of Depleted Uranium—Effects in Primary Cortical Neuron Cultures and in Caenorhabditis elegans

Depleted uranium (DU) is an extremely dense metal that is used in radiation shielding, counterbalances, armor, and ammunition. In light of the public concerns about exposure to DU and its potential role in Gulf War Syndrome (GWS), this study evaluated the neurotoxic potential of DU using focused studies on primary rat cortical neurons and the nematode Caenorhabditis elegans. We examined cell viability, cellular energy metabolism, thiol metabolite oxidation, and lipid peroxidation following exposure of cultured neurons to DU, in the form of uranyl acetate. We concurrently evaluated the neurotoxicity of uranyl acetate in C. elegans using various neuronal-green fluourescent protein reporter strains to visualize neurodegeneration. Our studies indicate that uranyl acetate has low cytotoxic potential, and uranium exposure does not result in significant changes in cellular energy metabolism, thiol metabolite oxidation, or lipid peroxidation. Furthermore, our C. elegans studies do not show any significant neurodegeneration following uranyl acetate exposure. Together, these studies suggest that DU, in the form of uranyl acetate, has low neurotoxic potential. These findings should alleviate the some of public concerns regarding DU as an etiologic agent of neurodegenerative conditions associated with GWS.

Glutathione status in the blood and tissues of patients with virus-originated hepatocellular carcinoma

OBJECTIVES

Glutathione status can be regarded as the redox status for many diseases. This study was performed to investigate the glutathione status in virus-originated hepatocellular carcinoma (HCC).

DESIGN AND METHODS

The blood and tissue samples were obtained from 24 patients. Blood samples were also obtained from 137 controls for comparison.

RESULTS

The GSH level and the ratios of GSH/GSSG and GSH/total glutathione of the blood samples from the patients were significantly lower than those of the controls, while the GSSG values were significantly higher. Meanwhile, levels of GSH and total glutathione, as well as the ratios of GSH/GSSH and GSH/total glutathione, were significantly decreased, whereas GSSG levels were significantly higher, in the HCC tissues than those of the adjacent cancer-free tissues.

CONCLUSIONS

Glutathione status in the HCC suggested that the antioxidant system is severely impaired, supporting a consistent role of the free radical cytotoxicity in the pathophysiology of the disease.

Therapeutic effects of alpha-lipoic acid on bleomycin-induced pulmonary fibrosis in rats

Pulmonary fibrosis (PF) is a major side effect of radiotherapy and chemotherapy. Recent clinical trials, unfortunately, have failed to identify any therapeutic agent which has the potential to reduce the consequences of this devastating condition. Reactive oxygen species and tissue remodeling regulators, such as metalloproteinases (MMPs) and their inhibitors (TIMPs), are thought to be involved in the development of PF. We investigated these factors to determine the protective effects of antioxidant alpha-lipoic acid (LA) against antineoplastic agent bleomycin (BLM)-induced oxidant lung toxicity in Sprague-Dawley rats. At different time intervals after BLM administration, pathological changes of the lung were analyzed with the measurement of total protein in bronchoalveolar lavage fluid (BALF), hydroxyproline (HYP) content and the level of three oxidative stress markers, i.e. malondialdehyde (MDA), the GSH/GSSG ratio, and total antioxidative capability (T-AOC). Also, the expression changes of MMP-1 and TIMP-1 were measured. At day 14 or 28 after BLM administration, protein content in BALF, and HYP, MDA and T-AOC contents of the lung increased significantly with a decreased GSH/GSSG ratio, implicating an increased efflux of GSSG from the lung and consumption of GSH. In contrast, treatment with LA protected BLM-induced pulmonary injury by suppressing oxidative stress with the reduction of MDA, and the enhancement of the GSH/GSSG ratio and T-AOC. The BLM-stimulated symptoms of PF were relieved with significant reduction of HYP and total proteins in LA-treated rats. LA also ameliorated the MMP-1/TIMP-1 ratio. These results suggest that LA inhibits BLM-induced lung toxicity associated with oxidative damage. Therefore, antioxidant LA has a potential therapeutic effect in the prevention and alleviation of PF.

[Genotoxicity of doxorubicin assessed on Saccharomyces cerevisiae cell model]

The genotoxicity of doxorubicin was assessed by the induction of ribonucleotide reductase gene expression and by the oxidative stress induction in Saccharomyces cerevisiae as a eukaryote cell model. Doxorubicin induced dose-dependent inhibition of cell proliferation, increased the intracell concentration of GSH and GSSG, and did not significantly influence the malonic dialdehyde concentration. Doxorubicin activated (independently of the concentration) ribonucleotide reductase gene expression, thus increasing GSH concentration. The increase in GSSG concentration is probably indicative of the development of oxidative stress in Saccharomyces cerevisiae cells, although this is not accompanied by an increase the MDA concentration in the cells.

Effect of T3 treatment on glutathione redox pool and its metabolizing enzymes in mitochondrial and post-mitochondrial fractions of adult rat testes

T3 (3,3', 5-triiodo-L-thyronine; 20 microg/100 g body weight/day in 0.01 N NaOH, i.p for 1, 3 and 5 days) treatment modulated reduced (GSH) and oxidized (GSSG) glutathione contents along with the activities of its metabolizing enzymes (such as glutathione peroxidase, glutathione reductase and glutathione S-transferase) in the testis of Wistar rats. However, the magnitude and nature of changes in the above biochemical parameters in response to T3 treatment were noticed to be different between mitochondrial and post-mitochondrial fractions. This was accompanied with elevated levels of lipid hydroperoxide and ascorbic acid in the crude homogenate of testis. The level of hydrogen peroxide in the post-mitochondrial fractions of testes did not change on first day, decreased on 3rd day and increased on 5th day of the hormone treatment when compared to respective controls. Nevertheless, its content in mitochondria was significantly elevated in response to all the three durations of the hormone treatment having the highest induction on 3rd day. The changes observed in the levels of GSH and GSSG and its metabolizing enzymes in response to T3 treatment reflect an alteration in the redox state of testis, which may be a causative factor for the impairment of testicular physiology as a consequence of oxidative stress.

Effects of energy restriction and fish oil supplementation on renal guanidino levels and antioxidant defences in aged lupus-prone B/W mice

Energy restriction (ER) and dietary fish oil (FO) are known to reduce the severity of glomerulonephritis and increase the lifespan of lupus-prone (NZB×NZW) F1(B/W) mice. In the present study, mice were fed eitherad libitumor energy-restricted (a 40 % lower energy intake than the dietad libitum), semi-purified diets containing 5 % maize oil or 5 % fish oil supplementation. To estimate the renal damage associated with oxidative stress, the total amounts of reactive oxygen species (ROS), cyclooxygenase-derived ROS and levels of guanidino compounds were measured. Additionally, we assessed the putative action of ER and FO on several key antioxidant enzymes measured in the kidney post-mitochondrial fraction. Results showed that the age-related increase in creatinine level was significantly reduced by ER and FO in old mice. In contrast, arginine and guanidino acetic acid levels showed a decrease with age but were increased by ER and FO. The GSH:GSSG ratio showed a significant decrease with age, whereas ER and FO feeding prevented the decrease. The age-related decrease in antioxidant scavenging superoxide dismutase, catalase and glutathione peroxidase activities were all reversed by ER and FO. The moderately decreased glutathione reductase and glutathione-S-transferase activities with age were significantly increased by ER and FO. Furthermore, the increased total ROS and cyclooxygenase-derived ROS levels were effectively reduced by ER and FO. In conclusion, our data strongly indicate that ER and FO maintain antioxidant status and GSH:GSSG ratio, thereby protecting against renal deterioration from oxidative insults during ageing.

Genetic variation in mouse beta globin cysteine content modifies glutathione metabolism: implications for the use of mouse models

Allelic variation in the mouse beta globin gene complex (Hbb) produces structurally different beta globins in different mouse strains. Like humans, mice with HbbS alleles produce a single beta globin with one reactive cysteine (beta Cys93). In contrast, mice with HbbD alleles produce two structurally different beta globins, each containing an additional cysteine (beta Cys13). beta Cys93 forms mixed disulfides with glutathione and plays a pivotal role in the activities of hemoglobin, glutathione, and nitric oxide. Similar roles for mouse beta Cys13 have not been described. We used capillary electrophoresis to compare reduced glutathione (GSH), glutathione disulfide (GSSG), and S-glutathionyl hemoglobin levels in erythrocytes from inbred C57BL/6J (homozygous HbbS/S) and 129S1/SvImJ (homozygous HbbD/D) mice and their homozygous and heterozygous B6129S/F2J hybrid offspring. S-glutathionyl hemoglobin was nearly undetectable in inbred or hybrid mice with only monocysteinyl beta globins (HbbS/S) but represented up to 10% of total hemoglobin in mice with polycysteinyl beta globins (HbbS/D or HbbD/D). The stepwise increase in beta globin sulfhydryl group concentration in HbbS/S, HbbS/D, and HbbD/D F2 mice was associated with increasing hemoglobin-bound glutathione and decreasing free glutathione (GSH + GSSG) concentrations. Total erythrocyte glutathione (GSH + GSSG + hemoglobin-bound) was not significantly different between groups. In vitro studies showed that beta Cys13 in mouse HbbD beta globins was more susceptible to disulfide exchange with GSSG than beta Cys93. We conclude that reactive beta globin sulfhydryl group concentration is genetically determined in mice, and that polycysteinyl beta globins markedly influence intraerythrocyte glutathione distribution between free and hemoglobin-bound compartments. Although Hbb heterozygosity and polycysteinyl beta globins are common in wild mouse populations, all common human beta globins contain only one reactive cysteine, and homozygosity is the norm. These fundamental differences in mouse and human beta globin genetics have important implications for the study of mouse biology and for the use of some mouse strains as models for humans.

Carvedilol inhibits mitochondrial complex I and induces resistance to H2O2 -mediated oxidative insult in H9C2 myocardial cells

Carvedilol, a beta-adrenoreceptor antagonist with strong antioxidant activity, produces a high degree of cardioprotection in a variety of experimental models of ischemic cardiac injury. Although growing evidences suggest specific effects on mitochondrial metabolism, how carvedilol would exert its overall activity has not been completely disclosed. In the present work we have investigated the impact of carvedilol-treatment on mitochondrial bioenergetic functions and ROS metabolism in H9C2 cells. This analysis has revealed a dose-dependent decrease in respiratory fluxes by NAD-dependent substrates associated with a consistent decline of mitochondrial complex I activity. These changes were associated with an increase in mitochondrial H(2)O(2) production, total glutathione and protein thiols content. To evaluate the antioxidant activity of carvedilol, the effect of the exposure of control and carvedilol-pretreated H9C2 cells to H(2)O(2) were investigated. The H(2)O(2)-mediated oxidative insult resulted in a significant decrease of mitochondrial respiration, glutathione and protein thiol content and in an increased level of GSSG. These changes were prevented by carvedilol-pretreatment. A similar protective effect on mitochondrial respiration could be obtained by pre-treatment of the cells with a sub-saturating amount of rotenone, a complex I inhibitor. We therefore suggest that carvedilol exerts its protective antioxidant action both by a direct antioxidant effect and by a preconditioning-like mechanism, via inhibition of mitochondrial complex I.

Antimelanogenic and Antioxidant Properties of Gallic Acid

To find novel skin-whitening agents, the melanogenesis inhibitory action of gallic acid (GA) was investigated. In this current study, the effects of GA on mushroom tyrosinase, tyrosinase inhibitory activity, and melanin content were assessed in B16 melanoma cells (B16 cells). Results indicated that GA has a strong antityrosinase activity (IC50=3.59x10(-6) M). Furthermore, data on murine tyrosinase activity and melanin biosynthesis revealed that GA effectively suppressed murine tyrosinase action and the amount of melanin. To investigate the relation between GA's inhibition of melanogenesis and antioxidant activity, the effect of GA on reactive species (RS) generation and the reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio in were determined in B16 cells. Results indicated that GA effectively down-regulated the RS generation and enhanced the GSH/GSSG ratio. Based on these results, I propose that GA exerts antimelanogenic activity coupled with antioxidant properties by suppressing RS generation and maintaining a higher GSH/GSSG ratio.

Exogenous hydrogen sulfide induces functional inhibition and cell death of cytotoxic lymphocytes subsets

The toxic effects of exogenous hydrogen sulfide on peripheral blood lymphocytes have been investigated in detail. Hydrogen sulfide is now considered as a gasotransmitter with specific functional roles in different cell types, like neurons and vascular smooth muscle. Here we show that exogenous hydrogen sulfide induces a caspase-independent cell death of peripheral blood lymphocytes that depends on their intracellular glutathione levels, with a physiologically relevant subset specificity for CD8+ T cells and NK cells. Although lymphocyte activation does not modify their sensitivity to HS-, after 24 h exposure to hydrogen sulfide surviving lymphocyte subsets show a dramatically decreased proliferation in response to mitogens and a reduced IL-2 production. Overall, our data demonstrate that HS- reduces the cellular cytotoxic response of peripheral blood lymphocytes as well as their production of IL-2, therefore de-activating the major players of local inflammatory responses, adding new basic knowledge to the clinically well known anti-inflammatory effects of sulfur compounds.

Stimulation of colonic mucosal growth associated with oxidized redox status in rats

Limited data in animal models suggest that colonic mucosa undergoes adaptive growth following massive small bowel resection (SBR). In vitro data suggest that intestinal cell growth is regulated by reactive oxygen species and redox couples [e.g., glutathione (GSH)/glutathione disulfide (GSSG) and cysteine (Cys)/cystine (CySS) redox]. We investigated the effects of SBR and alterations in redox on colonic growth indexes in rats after either small bowel transection (TX) or 80% midjejunoileal resection (RX). Rats were pair fed +/- blockade of endogenous GSH synthesis with buthionine sulfoximine (BSO). Indexes of colonic growth, proliferation, and apoptosis and GSH/GSSG and Cys/CySS redox potentials (E(h)) were determined. RX significantly increased colonic crypt depth, number of cells per crypt, and epithelial cell proliferation [crypt cell bromodeoxyuridine (BrdU) incorporation]. Administration of BSO markedly decreased colonic mucosal GSH, GSSG, and Cys concentrations in both TX and RX groups, with a resultant oxidation of GSH/GSSG and Cys/CySS E(h). BSO did not alter colonic crypt cell apoptosis but significantly increased all colonic mucosal growth indexes (crypt depth, cells/crypt, and BrdU incorporation) in both TX and RX groups in a time- and dose-dependent manner. BSO significantly decreased plasma GSH and GSSG, oxidized GSH/GSSG E(h), and increased plasma Cys and CySS concentrations. Collectively, these data provide in vivo evidence indicating that oxidized colonic mucosal redox status stimulates colonic mucosal growth in rats. The data also suggest that GSH is required to maintain normal colonic and plasma Cys/CySS homeostasis in these animal models.

Pro-oxidative effects of tea and polyphenols, epigallocatechin-3-gallate and epigallocatechin, on G6PD-deficient erythrocytes in vitro

Glucose-6-phosphate dehydrogenase (G6PD)-deficient subjects are vulnerable to chemical-induced hemolysis if exposed to oxidative agents. Recent studies reported that green tea and its constituents might act as pro-oxidants. Our objective was to investigate effects of tea and its polyphenolic components on the oxidative status of human G6PD-deficient erythrocytes. Erythrocytes of G6PD-deficient (n = 8) and normal (n = 8) subjects were incubated with water extracts of 3 types of tea samples (black tea, green tea and decaffeinated green tea extract) and 6 polyphenols. The resulting levels of reduced glutathione (GSH) and glutathione disulphide (GSSG), methemoglobin and plasma hemoglobin were quantified by HPLC and biochemical assays. The tea extracts significantly reduced GSH and increased GSSG levels in G6PD-deficient erythrocytes in a dose-dependent manner (0.5-10 mg/ml), but not in normal erythrocytes. Similar dose-dependent responses to (-)-epigallocatechin (EGC) and (-)-epigallocatechin-3-gallate (EGCG), but not to the other polyphenols, were observed. In G6PD-deficient cells, GSH was reduced by 43.3% (EGC at 0.05 mg/ml) and 33.3% (EGCG at 0.5 mg/ml), compared with pre-challenged levels. The concentration of methemoglobin was increased significantly when challenged with tea extracts, and EGC. Plasma hemoglobin levels were higher in G6PD-deficient samples after exposure to tea extracts, EGCG, EGC and gallic acid, compared with those in normal blood. Tea extracts and polyphenols significantly altered the oxidative status of G6PD-deficient erythrocytes in vitro as demonstrated by the decrease of GSH, and increased GSSG, methemoglobin and plasma hemoglobin. Our data caution against the excessive consumption of concentrated tea polyphenolic products by G6PD-deficient subjects.

Parameters of oxidative stress in saliva from diabetic and parenteral drug addict patients

BACKGROUND

Oxidative stress constitutes the basis for many diseases and it may account for the severity of systemic and oral disease complications. The aim of this study was to assess whether saliva may be used to detect the body's oxidative stress level.

METHODS

Oxidative stress was determined in saliva from 14 diabetic patients and 10 heroin addicts; two different pathologic conditions related to free radical damage, and 21 healthy control subjects were included in the study. Glutathione peroxidase (GPx) and reductase (GRd) activities, and glutathione (GSH) and glutathione disulfide (GSSG) levels were analyzed in the saliva of all individuals. Other variables including salivary volume and the oral status were also analyzed.

RESULTS

Diabetic patients had GPx and GRd activities of 39.98 +/- 1.61 and 6.19 +/- 0.61 nmol/min/mg prot, respectively. These values were significantly higher (P < 0.001) than those obtained in control saliva (27.51 +/- 0.86 and 3.44 +/- 0.25 nmol/min/mg prot, respectively). Drug addicts showed significantly (P < 0.001) lower salivary GPx and GRd activities than controls. Both group of patients had significantly lower levels of GSH and higher of GSSG than controls (P < 0.001).

CONCLUSIONS

Changes in the antioxidant enzymes and glutathione levels in saliva from two different pathologic situations as those here studied suggest that this biologic fluid may be suitable for determining the prognosis and evolution of these diseases and its oral manifestations.

Relationship between oxidative stress and antioxidant systems in the liver of patients with Wilson disease: hepatic manifestation in Wilson disease as a consequence of augmented oxidative stress

The role of oxidative stress in the pathogenesis of liver disease in Wilson disease (WD), a genetic disorder characterized by excess hepatic deposition of copper that generates free radicals, remains unclear. This study investigates oxidative stress on the liver and hepatic antioxidant responses in WD using liver specimens from affected patients showing mild liver damage (group I, n = 3), moderate or greater liver damage (group II, n = 5), and fulminant hepatic failure (group III, n = 5) and from asymptomatic carriers (n = 2). Decreased ratios of reduced glutathione (GSH) to oxidized glutathione (GSSG) and increased thiobarbituric acid reactive substance (TBARS), a lipid peroxidation product, were found in every affected patient, especially in group II and III patients. Activities and protein expressions of Mn-dependent superoxide dismutase (Mn-SOD), CuZn-dependent superoxide dismutase (CuZn-SOD), and catalase were decreased in all patients, especially in group III patients. Glutathione peroxidase (GPx) activity was decreased only in group III patients. Asymptomatic carriers without any clinical manifestations showed normal TBARS level and GSH/GSSG ratio with increases in both GSH and GSSG levels. Their CuZn-SOD, Mn-SOD, and catalase activities were increased. These results suggest that excessive copper-derived oxidants contribute to development and progression of liver disease in WD.

Isolation of chebulic acid from Terminalia chebula Retz. and its antioxidant effect in isolated rat hepatocytes

A hepatoprotective compound was isolated from the ethanolic extract of the fruits of Terminalia chebula Retz. by consecutive solvent partitioning, followed by silica gel and Sephadex LH-20 column chromatographies. The purified compound was identified as a mixture of chebulic acid and its minor isomer, neochebulic acid, with a ratio of 2:1 by spectroscopic analysis including 1D and 2D NMR and MS spectroscopy. To our knowledge, this is the first report on the protection of rat hepatocytes against oxidative toxicity by chebulic acid obtained from T. chebula Retz. This compound exhibited in vitro a free radical-scavenging activity and ferric-reducing antioxidant activity. Also, the specific ESR spectrum for the (*)OOH radical signals consisting of three-line ESR spectra was within the field of 0.27 mT, whereas 2.5 and 0.25 mg/ml of chebulic acid significantly reduced the signal intensity of the ESR spectra to 0.06 mT and 0.11 mT, respectively. Using isolated rat hepatocyte experiment, we demonstrated that the treatment of hepatocytes with chebulic acid significantly reduced the tert-butyl hydroperoxide (t-BHP)-induced cell cytotoxicity, intracellular reactive oxygen species level, and the ratio of GSSH, oxidized form of glutathione (GSH) to the over total GSH (GSH + GSSG) (4.42%) as compared to that with t-BHP alone (8.33%).

Cytotoxic effect of As(III) in Caco-2 cells and evaluation of its human intestinal permeability

Inorganic arsenic has been classified as a carcinogen for humans (Group I). However, its transit across the human intestinal epithelium has not been characterized. Using Caco-2 cells, the thiol-redox balance and apparent permeability coefficients (P(app)) for As(III) in the apical to basolateral (AP-BL) and basolateral to apical (BL-AP) direction were evaluated. After As(III) exposure, GSH-induced synthesis was observed, increasing the GSH/GSSG ratio by elevating the As(III) concentration. The AP-BL permeabilities decreased as the As(III) concentrations increased, indicating the existence of a mediated transport mechanism. The (BL-AP)/(AP-BL) permeability ratios were higher than unity, suggesting the existence of a secretion process.

Glucose 6-phosphate dehydrogenase overexpression models glucose deprivation and sensitizes lymphoma cells to apoptosis

Glucocorticoids are one component of combined treatment regimens for many types of lymphoma due to their ability to induce apoptosis in lymphoid cells. In WEHI7.2 murine thymic lymphoma cells, altering catalase and glutathione peroxidase activity by transfection or the use of chemical agents modulates the ability of glucocorticoids to induce apoptosis. This suggests that the oxidative stress response is important in determining the glucocorticoid sensitivity of the cells. For glutathione peroxidase and catalase to detoxify reactive oxygen species (ROS), reducing equivalents in the form of nicotinamide adenine dinucleotide phosphate, reduced form (NADPH) are ultimately required. The major source of NADPH in the cell is glucose 6-phosphate dehydrogenase (G6PDH). Therefore, we created G6PDH-overexpressing WEHI7.2 variants to test whether G6PDH activity is a key determinant of glucocorticoid sensitivity in WEHI7.2 cells. G6PDH-overexpressing WEHI7.2 cells were more sensitive to oxidative stress and glucocorticoids. The G6PDH-overexpressing WEHI7.2 variants appeared similar to cells undergoing glucose deprivation with decreased adenosine triphosphate (ATP) synthesis by the mitochondria and increased basal levels of ROS. Overexpression of G6PDH also sensitized the cells to other standard lymphoma chemotherapeutics including cyclophosphamide, doxorubicin, and vincristine. The decreased ATP and elevated ROS due to G6PDH overexpression may be key factors in increasing the sensitivity of the WEHI7.2 cells to lymphoma chemotherapeutics.

Analysis of glutathione and glutathione disulfide in human saliva using hydrophilic interaction chromatography with mass spectrometry

A sensitive method for the determination of glutathione (GSH) and glutathione disulfide (GSSG) in human saliva was developed and validated. GSH was captured and stabilized by the addition of N-ethylmaleimide (NEM). Solid-phase extraction (SPE) using an Oasis MAX extraction cartridge was employed for sample preparation and analysis was performed on a Shimadzu LCMS-2010 A that was operated in the single ion monitoring mode using positive ion electrospray ionization (ESI) as the interface. The monitored ion for GSH-NEM was m/z 433 and that for GSSG was m/z 613. Chromatography was carried out on an Atlantis HILIC silica column (150 mm x 2.1 mm, 5 microm) with acetonitrile and formate buffer as the mobile phase at the flow rate of 0.2 ml/min. The calibration curve was linear over the range of 0.1-100 microM for GSH-NEM. The extraction recoveries of GSH-NEM spiked at concentrations of 25 and 50 microM were 97.1 and 104.4%, respectively. Similar results were obtained for GSSG. The newly developed hydrophilic interaction chromatography with mass spectrometry (HILIC/MS) method showed superior sensitivity for the determination of GSH and GSSG in human saliva samples.