Neuroprotective effects of dehydroepiandrosterone (DHEA) in rat model of Alzheimer's disease

The current study was undertaken to elucidate a possible neuroprotective role of dehydroepiandrosterone (DHEA) against the development of Alzheimer's disease in experimental rat model. Alzheimer's disease was produced in young female ovariectomized rats by intraperitoneal administration of AlCl(3) (4.2 mg/kg body weight) daily for 12 weeks. Half of these animals also received orally DHEA (250 mg/kg body weight, three times weekly) for 18 weeks. Control groups of animals received either DHAE alone, or no DHEA, or were not ovariectomized. After such treatment the animals were analyzed for oxidative stress biomarkers such as hydrogen peroxide, nitric oxide and malondialdehyde, total antioxidant capacity, reduced glutathione, glutathione peroxidase, glutathione reductase, superoxide dismutase and catalase activities, antiapoptotic marker Bcl-2 and brain derived neurotrophic factor. Also brain cholinergic markers (acetylcholinesterase and acetylcholine) were determined. The results revealed significant increase in oxidative stress parameters associated with significant decrease in the antioxidant enzyme activities in Al-intoxicated ovariectomized rats. Significant depletion in brain Bcl-2 and brain-derived neurotrophic factor levels were also detected. Moreover, significant elevations in brain acetylcholinesterase activity accompanied with significant reduction in acetylcholine level were recorded. Significant amelioration in all investigated parameters was detected as a result of treatment of Al-intoxicated ovariectomized rats with DHEA. These results were confirmed by histological examination of brain sections. These results clearly indicate a neuroprotective effect of DHEA against Alzheimer's disease.     

Relationship Between Sonic Hedgehog Protein, Brain-Derived Neurotrophic Factor and Oxidative Stress in Autism Spectrum Disorders

The etiology of autism spectrum disorders (ASD) is not well known but oxidative stress has been suggested to play a pathological role. We report here that the serum levels of Sonic hedgehog (SHH) protein and brain-derived neurotrophic factor (BDNF) might be linked to oxidative stress in ASD. By using the whole blood or polymorphonuclear leukocytes, we demonstrated that autistic children produced a significantly higher level of oxygen free radicals (OFR). In addition, we found significantly higher levels of serum SHH protein in children with mild as well as severe form of autism. We also found that the serum level of BDNF was significantly reduced in autistic children with mild form of the disorder but not with severe form of the disorder. Our findings are the first to report a correlation between SHH, BDNF and OFR in autistic children, suggesting a pathological role of oxidative stress and SHH in autism spectrum disorders.     

Neuroprotective effect of rutin against colistin-induced oxidative stress,inflammation and apoptosis in rat brain associated with the CREB/BDNF expressions

The purpose of the current study was to examine the neuroprotective effect of rutin against colistin-induced neurotoxicity in rats. Thirty-five male Sprague Dawley rats were randomly divided into 5 groups. The control group (orally received physiological saline), the rutin group (orally administered 100 mg/kg body weight), the colistin group (i.p. administered 15 mg/kg body weight), the Col?+?Rut 50 group (i.p. administered 15 mg/kg body weight of colistin, and orally received 50 mg/kg body weight of rutin), the Col?+?Rut 100 group (i.p. administered 15 mg/kg body weight of colistin, and orally received 100 mg/kg body weight of rutin). Administration of colistin increased levels of glial fibrillary acidic protein and brain-derived neurotrophic factor and acetylcholinesterase and butyrylcholinesterase activities while decreasing level of cyclic AMP response element binding protein and extracellular signal regulated kinases 1 and 2 (ERK1/2) expressions. Colistin increased oxidative impairments as evidenced by a decrease in level of nuclear factor erythroid 2-related factor 2 (Nrf-2), glutathione, superoxide dismutase, glutathione peroxidase and catalase activities, and increased malondialdehyde content. Colistin also increased the levels of the apoptotic and inflammatoric parameters such as cysteine aspartate specific protease-3 (caspase-3), p53, B-cell lymphoma-2 (Bcl-2), nuclear factor kappa B (NF-κB), Bcl-2 associated X protein (Bax), tumor necrosis factor-α (TNF-α) and neuronal nitric oxide synthase (nNOS). Rutin treatment restored the brain function by attenuating colistin-induced oxidative stress, apoptosis, inflammation, histopathological and immunohistochemical alteration suggesting that rutin supplementation mitigated colistin-induced neurotoxicity in male rats.

     

Protective effect of propolis against oxidative stress and immunosuppression induced by oxytetracycline in rainbow trout (Oncorhynchus mykiss, W.)

The aim of this study was to investigate the effects of propolis on oxytetracycline (OTC)-induced oxidative stress and immunosuppression in fish. OTC (100 mg per kg?1 body weight) was orally administered to fish for 14 days. A significant elevation in the level of malondialdehyde, as an index of lipid peroxidation, and reductions in antioxidant enzyme activities (superoxide dismutase, catalase, and glutathione peroxidase) and low molecular weight antioxidant (reduced glutathione) levels were observed in the blood, liver, kidney, spleen, and heart tissues of OTC-treated fish. OTC also had a suppressive effect on specific and non-specific immune system parameters, such as leucocyte counts, oxidative radical production (nitrobluetetrazolium activity), total plasma protein and immunoglobulin levels, and phagocytic activity. Pre-treatment, post-treatment, and simultaneous treatment with propolis (50 mg per kg?1 body weight, orally) attenuated the OTC-induced oxidative stress by significantly decreasing the levels of malondialdehyde in tissues. In addition, propolis significantly increased the level of reduced glutathione and the catalase, glutathione peroxidase, and superoxide dismutase activities. Upon the administration of propolis, the suppressed immune system parameters were significantly increased in fish treated with OTC. The present results suggest that pre-treatment, post-treatment, and simultaneous administration of propolis might alleviate OTC-induced oxidative stress and immunosuppression.     

Retinol supplementation induces oxidative stress and modulates antioxidant enzyme activities in rat sertoli cells

Recent intervention studies revealed that supplementation with retinoids resulted in a higher incidence of lung cancer. Recently the causal mechanism has begun to be clarified. We report here that retinol caused cellular oxidative stress and modulated superoxide dismutase, catalase and glutathione peroxidase activities. Retinol (7 μM) significantly increased TBARS, conjugated dienes, and hydroperoxide-initiated chemiluminescence in cultured Sertoli cells. In response to retinol treatment superoxide dismutase, catalase and glutathione peroxidase activities increased. TBARS content and catalase activities were decreased by a free radical scavenger. These findings suggest that retinol may induce oxidative stress and modulate antioxidant enzyme activities in Sertoli cells.     

Lipid peroxidation and antioxidant status in blood of patients with uterine myoma, endometrial polypus, hyperplastic and malignant endometrium

Oxidative stress is considered to be involved in pathogenesis of many disorders of the female genital tract. In this study, we explored the lipid peroxidation levels and antioxidant enzyme activities in women diagnosed with different forms of uterine diseases in order to evaluate the extent of oxidative stress in blood of such patients. Blood samples of healthy subjects and gynecological patients were collected and subjected to assays for superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and lipid hydroperoxides. The results show that alterations of measured parameters vary with the enzyme type and diagnosis. However, both reduction in antioxidants and elevation of lipid peroxidation were observed in general. Lipid hydroperoxides level was negatively correlated to superoxide dismutase and glutathione peroxidase activities, as well as positively correlated to catalase activity. In addition, the lipid hydroperoxides/ glutathione peroxidase ratio was found to be increased, according to the type of uterine disease. The obtained results show that perturbation of antioxidant status is more pronounced in blood of patients with premalignant (hyperplastic) and malignant (adenocarcinoma) lesions, compared to those with benign uterine changes such as polypus and myoma.     

Antioxidant defense and apoptotic effectors in ascorbic acid and β-glycerophosphate-induced osteoblastic differentiation

MC3T3-E1 cells grown in the presence of ascorbic acid and β-glycerophosphate (AA/β-GP) express alkaline phosphatase and produce an extensive collagenous extracellular matrix. Differentiated MC3T3-E1 cells are more sensitive to hydrogen peroxide-induced oxidative stress than undifferentiated cells. In this study, we compared the profile of antioxidant enzymes and molecular markers of apoptosis in undifferentiated and differentiated MC3T3-E1 cells (cell differentiation was induced by treatment with AA/β-GP). Differentiated osteoblasts showed lower expression and activity of catalase, glutathione S-transferase and glutathione peroxidase. The total superoxide dismutase activity and the expression of Cu/Zn superoxide dismutase were also lower, while the expression of Mn superoxide dismutase was higher in differentiated osteoblasts. The level of malondialdehyde, a widely used marker for oxidative stress, was lower in the AA/β-GP group compared with control cells, but this difference was not significant. Western blotting showed that treatment with AA/β-GP increased the Bax/Bcl-2 ratio used as an index of cellular vulnerability to apoptosis. In addition, the activities of caspases 3, 8 and 9 and cleaved poly (ADP) ribose polymerase were significantly higher in differentiated cells. These findings provide new insights into how changes in the activities of major antioxidant enzymes and in the signaling pathways associated with apoptosis may influence the susceptibility of bone cells to oxidative stress.     

Sonic Hedgehog Protects Cortical Neurons Against Oxidative Stress

Oxidative stress is one of the most important pathological mechanisms in neurodegenerative diseases and ischemia. Recent studies have indicated that the sonic hedgehog (SHH) signaling pathway is involved in these diseases, but the underlying mechanisms remains elusive. Here we report that the SHH pathway was activated in primary cultured cortical neurons after exposure to hydrogen peroxide (H₂O₂). H₂O₂ treatment decreased the cell viability of neurons, and inhibition of endogenous SHH signaling exacerbated its neurotoxicity. Activation of SHH signaling protected neurons from H₂O₂-induced apoptosis and increased the cell viability while those effects were partially reversed by blocking SHH signals. Exogenous SHH increased the activities of Superoxide dismutase (SOD) and Glutathione peroxidase (GSH-PX) in H₂O₂-treated neurons and decreased production of Malondialdehyde (MDA). It also promoted expression of the anti-apoptotic gene Bcl-2 and inhibited expression of pro-apoptotic gene Bax. Activation of SHH signals upregulated both Neurotrophic factors vascular endothelial growth factor (VEGF) and brain-derived neurotrophic factor (BDNF). Pretreatment with SHH inhibited the activation of ERK (extracellular signal-regulated kinases) signals induced by H₂O₂. Our findings demonstrate that activation of SHH signaling protects cortical neurons against oxidative stress and suggest a potential role of SHH for the clinic treatments of brain ischemia and neurodegenerative disorders.     

Retinol supplementation induces oxidative stress and modulates antioxidant enzyme activities in rat Sertoli cells

Recent intervention studies revealed that supplementation with retinoids resulted in a higher incidence of lung cancer. Recently the causal mechanism has begun to be clarified. We report here that retinol caused cellular oxidative stress and modulated superoxide dismutase, catalase and glutathione peroxidase activities. Retinol (7 μM) significantly increased TBARS, conjugated dienes, and hydroperoxide-initiated chemiluminescence in cultured Sertoli cells. In response to retinol treatment superoxide dismutase, catalase and glutathione peroxidase activities increased. TBARS content and catalase activities were decreased by a free radical scavenger. These findings suggest that retinol may induce oxidative stress and modulate antioxidant enzyme activities in Sertoli cells.     

Response of the cultivated tomato and its wild salt-tolerant relative Lycopersicon pennellii to salt-dependent oxidative stress: increased activities of antioxidant enzymes in root plastids

Root plastids of the cultivated tomato Lycopersicon esculentum (Lem) exhibited salt-induced oxidative stress as indicated by the increased H 2 O 2 and lipid peroxidation levels which were accompanied with increased contents of the oxidized forms of ascorbate and glutathione. In contrast, H 2 O 2 level decreased, lipid peroxidation level slightly decreased and the levels of the reduced forms of ascorbate and glutathione increased in plastids of L. pennellii (Lpa) species in response to salinity. This better protection of Lpa root plastids from salt-induced oxidative stress was correlated with increased activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidases (POD), monodehydroascorbate reductase (MDHAR), glutathione peroxidase (GPX), glutathione- S -transferase (GST) and phospholipid hydroperoxide glutathione peroxidase (PHGPX). In the plastids of both species, activities of SOD, APX, and POD could be resolved into several isozymes. In Lem plastids two Cu/ZnSOD isozymes were found whereas in Lpa an additional FeSOD type could also be detected. In response to salinity, activities of selected SOD, APX, and POD isozymes were increased in Lpa, while in Lem plastids the activities of most of SOD and POD isozymes decreased. Taken together, it is suggested that plastids play an important role in the adaptation of Lpa roots to salinity.     

Effect of overexpression of Bcl-2 on cellular oxidative damage, nitric oxide production, antioxidant defenses, and the proteasome

Bcl-2 is a gene family involved in the suppression of apoptosis in response to a wide range of cellular insults. Multiple papers have suggested a link between Bcl-2 and oxidative damage/antioxidant protection. We therefore examined parameters of antioxidant defense and oxidative damage in two different cell lines, NT-2/D1 (NT-2) and SK-N-MC, overexpressing Bcl-2 as compared with vector-only controls. Bcl-2 transfectants of both cell lines were more resistant to H₂O₂ and showed increases in GSH level and Cu/Zn-superoxide dismutase (SOD1) activity, but not in Mn-superoxide dismutase, glutathione peroxidase, or glutathione reductase activities. Catalase activity was increased in SK-N-MC cells. Overexpression of Bcl-2 did not significantly decrease levels of oxidative DNA damage (measured as 8-hydroxyguanine) or lipid peroxidation, but it decreased levels of 3-nitrotyrosine in both cell lines and protein carbonyls in SK-N-MC cells only. It also increased proteasome activity in both cell lines. We conclude that Bcl-2 raises cellular antioxidant defense status, but this is not necessarily reflected in decreased levels of oxidative damage to DNA and lipids. The ability of Bcl-2 overexpression to decrease 3-nitrotyrosine levels suggests that it may decrease formation of peroxynitrite or other reactive nitrogen species; this was confirmed as decreased production of NO₂⁻/NO₃⁻ in the transfected cells and a fall in the level of nNOS protein.     

Mitochondrial defects and oxidative damage in patients with peripheral arterial disease

Abnormal mitochondrial function is present in patients with peripheral arterial disease and may contribute to its clinical manifestations. However, the specific biochemical mitochondrial defects and their association with increased oxidative stress have not been fully characterized. Gastrocnemius muscle was obtained from peripheral arterial disease patients (n = 25) and age-matched controls (n = 16) and mitochondrial parameters were measured. Complexes I through IV of the electron transport chain were individually evaluated to assess for isolated defects. Muscle was also evaluated for protein and lipid oxidative changes by measuring the levels of protein carbonyls, lipid hydroperoxides, and total 4-hydroxy-2-nonenal binding and for the activities of the antioxidant enzymes superoxide dismutase, catalase, and glutathione peroxidase. Mitochondrial electron transport chain complexes I, III, and IV in arterial disease patients demonstrated significant reductions in enzymatic activities and mitochondrial respiration compared to controls. Oxidative stress biomarker analysis demonstrated significantly increased levels of protein carbonyls, lipid hydroperoxides, and 4-hydroxy-2-nonenal compared to control muscle. Antioxidant enzyme activities were altered, with a significant decrease in superoxide dismutase activity and significant increases in catalase and glutathione peroxidase. Peripheral arterial disease is associated with abnormal mitochondrial function and evidence of significant oxidative stress.     

Effects of piperine on antioxidant pathways in tissues from normal and streptozotocin-induced diabetic rats

Using diabetes mellitus as a model of oxidative damage, this study investigated whether subacute treatment (10 mg/kg/day, intraperitoneally for 14 days) with the compound piperine would protect against diabetes-induced oxidative stress in 30-day streptozotocin-induced diabetic Sprague-Dawley rats. Liver, kidney, brain, and heart were assayed for degree of lipid peroxidation, reduced and oxidized glutathione (GSH and GSSG, respectively) content, and activities of the free-radical detoxifying enzymes catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase. Piperine treatment of normal rats enhanced hepatic GSSG concentration by 100% and decreased renal GSH concentration by 35% and renal glutathione reductase activity by 25% when compared to normal controls. All tissues from diabetic animals exhibited disturbances in antioxidant defense when compared with normal controls. Treatment with piperine reversed the diabetic effects on GSSG concentration in brain, on renal glutathione peroxidase and superoxide dismutase activities, and on cardiac glutathione reductase activity and lipid peroxidation. Piperine treatment did not reverse the effects of diabetes on hepatic GSH concentrations, lipid peroxidation, or glutathione peroxidase or catalase activities; on renal superoxide dismutase activity; or on cardiac glutathione peroxidase or catalase activities. These data indicate that subacute treatment with piperine for 14 days is only partially effective as an antioxidant therapy in diabetes.     

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

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

The effect ofGongronema latifolium extracts on serum lipid profile and oxidative stress in hepatocytes of diabetic rats

Diabetes is known to involve oxidative stress and changes in lipid metabolism. Many secondary plant metabolites have been shown to possess antioxidant activities, improving the effects of oxidative stress on diabetes. This study evaluated the effects of extracts from Gongronema latifolium leaves on antioxidant enzymes and lipid profile in a rat model of non insulin dependent diabetes mellitus (NIDDM). The results confirmed that the untreated diabetic rats were subjected to oxidative stress as indicated by significantly abnormal activities of their scavenging enzymes (low superoxide dismutase and glutathione peroxide activities), compared to treated diabetic rats, and in the extent of lipid peroxidation (high malondialdehyde levels) present in the hepatocytes. The ethanolic extract of G. latifolium leaves possessed antioxidant activity as shown by increased superoxide dismutase and glutathione peroxidase activities and decreases in malondialdehyde levels. High levels of triglycerides and total cholesterol, which are typical of the diabetic condition, were also found in our rat models of diabetes. The ethanolic extract also significantly decreased triglyceride levels and normalized total cholesterol concentration.     

A bentazone-resistant mutant of cyanobacterium,Synechococcus elongatus PCC7942 adapts different strategies to counteract on bromoxynil- and salt-mediated oxidative stress

A bentazone-resistant mutant of Synechococcus elongatus PCC7942, called Mu2, tolerated elevated NaCl concentrations. As bentazone and bromoxynil exhibit similar mechanism of action, we investigated whether the mutant also toleratedbromoxynil and found it to be true. The line of investigation was then whether the acclimation strategy for the three stressors, bentazone, bromoxynil and NaCl was same or different. The cellular contents of malondialdehyde, hydrogen peroxide and superoxide increased in wild type strain following all the treatments suggesting their toxicities due to oxidative response. Notwithstanding, there were apparently different anti-oxidative measures pertaining to the herbicide and salinity stress. Glutathione contents and activities of superoxide dismutase, catalase-peroxidase, glutathione S-transferase and glutathione reductase decreased under NaCl, whereas bromoxynil affected only glutathione S-transferase reductase. Moreover, in-gel assays revealed that bromoxynil promoted appearance of isozymes of catalase-peroxidase, while NaCl induced such response only for superoxide dismutase. On the other hand, in Mu2, glutathione peroxidase-reductase and glutathione showed upward trend after bromoxynil exposure, whereas NaCl raised peroxidase and superoxide dismutase. Proteome comparison revealed peroxiredoxin Q to be highly expressed in wild type strain under bromoxynil, whereas NaCl favoured flavodoxin over-expression. Their amounts were already high in Mu2. We suggest that Mu2 acclimatized to bromoxynil in a manner similar to bentazone by upgrading peroxiredoxin Q and glutathione peroxidase-reductase. Conversely, for NaCl it devised another mechanism involving peroxidase and superoxide dismutase, and flavodoxin.     

Endogenous antioxidant defence system in rat liver following mercury chloride oral intoxication

Mercury is a highly toxic metal which induces oxidative stress. Superoxide dismutases, catalase, and glutathion peroxidase are proteins involved in the endogenous antioxidant defence system. In the present study rats were administered orally, by gavage, a single daily dose of HgCl2 for three consecutive days. In order to find a relation between the proteins involved in the antioxidant defence and mercury intoxication, parameters of liver injury, redox state of the cells, as well as intracellular protein levels and enzyme activities of Mn-dependent superoxide dismutase (MnSOD), Cu-Zn-dependent superoxide dismutase (CuZnSOD), catalase, and glutathione peroxidase (GPx) were assayed both in blood and in liver homogenates. HgCl2 at the doses of 0.1 mg/kg produced liver damage which that was detected by a slight increase in serum alanine aminotransferase and gamma glutamyl transferase. Hepatic GSH/GSSG ratio was assayed as a parameter of oxidative stress and a significant decrease was detected, as well as significant increases in enzyme activities and protein levels of hepatic antioxidant defence systems. Changes in both MnSOD and CuZnSOD were parallel to those of liver injury and oxidative stress, while the changes detected in catalase and GPx activities were progressively increased along with the mercury intoxication. Other enzyme activities related to the glutathione redox cycle, such as glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G6PDH), also increased progressively. We conclude that against low doses of mercury that produce a slight oxidative stress and liver injury, the response of the liver was to induce the synthesis and activity of the enzymes involved in the endogenous antioxidant system. The activities of all the enzymes assayed showed a rapidly induced coordinated response.     

Influence of treatment of diabetic rats with combinations of pycnogenol, beta-carotene, and alpha-lipoic acid on parameters of oxidative stress

Treatment with antioxidants may act more effectively to alter markers of free radical damage in combinations than singly. This study has determined whether treatment with combinations of pycnogenol, beta-carotene, and alpha-lipoic acid was more effective at reducing oxidative stress in diabetic rats than treatment with these antioxidants alone. It is not feasible, based on this study, to assume that there are interactive effects that make combinations of these antioxidants more effective than any one alone to combat oxidative stress. Female Sprague-Dawley rats, normal and streptozotocin-induced diabetic, were treated (10 mg/kg/day ip for 14 days) with pycnogenol, beta-carotene, pycnogenol + beta-carotene, or pycnogenol + beta-carotene + alpha-lipoic acid; controls were untreated. Concentrations of thiobarbituric acid reactive substances, glutathione and glutathione disulfide, and activities of glutathione reductase, glutathione peroxidase, superoxide dismutase, and catalase were measured in liver, kidney, and heart. Four types of effects were observed: (1) treatment with beta-carotene alone either reversed (cardiac glutathione disulfide) or elevated (cardiac glutathione, hepatic glutathione peroxidase activity) levels seen in diabetic animals; (2) beta-carotene alone produced no effect, but pycnogenol both alone and in combinations elevated (renal glutathione peroxidase and glutathione reductase activities, hepatic glutathione reductase activity and glutathione disulfide) or depressed (cardiac glutathione disulfide) levels seen in untreated diabetic animals; (3) all treatments with antioxidants, either alone or in combination, either normalized (lipid peroxidation in all tissues), elevated (hepatic GSH, cardiac glutathione peroxidase activity), or had no effect on (activities of hepatic catalase and superoxide dismutase in all tissues) levels seen in diabetic animals; (4) in only one case (cardiac glutathione reductase activity) levels in diabetic animals treated with combinations of antioxidants were normal, but elevated in animals treated with either antioxidant alone. Antioxidant effects seem to be dependent on the nature of the antioxidant used and not on combination effects.     

Quantitative determination of ortho- and meta-tyrosine as biomarkers of protein oxidative damage in beta-thalassemia

Oxidative stress in thalassemia is caused by secondary iron overload and stems from blood transfusion and increased iron uptake. In this study, we hypothesized that levels of o- and m-tyrosine, products of hydroxyl radical attack on phenylalanine, would be elevated in beta-thalassemia (intermediate). This study represents the first report in which specific markers of protein oxidative damage have been quantified in thalassemia. We used GC/MS to assay o- and m-tyrosine at the femtomole level using only a few microliters of plasma. Levels of both markers were significantly higher in patients with beta-thalassemia than in controls and were positively correlated with serum ferritin, malondialdehyde, superoxide dismutase, glutathione peroxidase and glutathione. We conclude that o- and m-tyrosine are useful biomarkers of oxidative damage to proteins in thalassemia (intermediate) and may also be useful markers in other iron overload diseases. Positive correlations between o- and m-tyrosine levels and malondialdehyde as well as antioxidants such as superoxide dismutase, glutathione peroxidase and glutathione, are indicative of the broad impact of oxidative stress on blood plasma in thalassemia, with up-regulation of antioxidant proteins probably reflecting a homeostatic response to these increased stress levels.