Antioxidant defence mechanisms: from the beginning to the end (of the beginning)

Proteomics in investigation of protein nitration in kidney disease: technical challenges and perspectives from the spontaneously hypertensive rat

Kidneys are the mammalian organs with widest range of oxidative status ranging from the well-perfused cortex to the relatively anoxic medulla. This organ is of key interest from the perspective of hypertension, an important contributor to human mortality, and there has been growing use of the spontaneously hypertensive rat (SHR) as a model to explore oxidative stress in hypertensive kidney. Nitrosative stress is often associated with oxidative stress and, like oxidative stress, can lead to covalent modification of protein side-chains. It is especially relevant to kidney because of high levels of both nitrite/nitrate and nitric oxide synthase in medulla. Because of their relatively low abundance and their well-known role in signal transduction, nitration of tyrosines to 3-nitrotyrosines (3NT) is of particular interest in this regard. This modification has the potential to contribute to changes in regulation, in protein activity and may provide a means of specific targeting of key proteins. Mass spectrometry (MS) offers a promising route to detecting this modification. This review surveys protein nitration in kidney disease and highlights opportunities for MS detection of nitrated residues in the SHR.

Oxidative stress and antioxidants in hepatic pathogenesis

Long term hepatitis B virus (HBV) infection is a major risk factor in pathogenesis of chronic liver diseases, including hepatocellular carcinoma (HCC). The HBV encoded proteins, hepatitis B virus X protein and preS, appear to contribute importantly to the pathogenesis of HCC. Both are associated with oxidative stress, which can damage cellular molecules like lipids, proteins, and DNA during chronic infection. Chronic alcohol use is another important factor that contributes to oxidative stress in the liver. Previous studies reported that treatment with antioxidants, such as curcumin, silymarin, green tea, and vitamins C and E, can protect DNA from damage and regulate liver pathogenesis-related cascades by reducing reactive oxygen species. This review summarizes some of the relationships between oxidative stress and liver pathogenesis, focusing upon HBV and alcohol, and suggests antioxidant therapeutic approaches.

The relationship between serum biotin and oxidant/antioxidant activities in bovine lameness

Serum biotin concentrations, erythrocyte superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), reduced glutathione (GSH) and plasma thiobarbituric acid reactive substances (TBARS) were measured in 36 dairy cows, 18 of them were healthy and served as control. In the 18 cows with lameness problems, there were 5 cows with interdigital necrobacillosis, 5 cows with subsolar abscessation, 2 cows with solar ulcers, 2 cows with white line disease, 2 cows with chronic laminitis and 2 cows with septic arthritis. The degree of lameness was estimated to be slight in 3 cows, moderate in 11 cows and severe in 4 cows. Plasma fibrinogen levels and TBARS concentrations were increased significantly (P≤0.05) in lame cows compared to control group. The antioxidant enzymes GSH-Px, and CAT concentrations were increased significantly (P≤0.05) in lame cows. The level of reduced glutathione and the activity of SOD were significantly decreased in affected cows compared to healthy ones. Serum biotin levels in healthy cows ranged from 2.25 to 3.5ng/ml while in lame cows, biotin levels ranged from 1.17 to 2.3ng/ml. Biotin levels correlated positively with blood GSH (r=0.870, P≤0.05), (r=0.735, P≤0.05) and with GSH-Px (r=0.539, P≤0.05), (r=0.637, P≤0.05) and with SOD (r=0.637, P≤0.05), (r=0.449, P≤0.05) and with catalase (r=0.533, P≤0.05), (r=0.585, P≤0.05) in both healthy and lameness affected subjects, respectively.

Ethanol and acetaldehyde disturb TNF-alpha and IL-6 production in cultured astrocytes

Ethanol disturbs astroglial growth and differentiation and causes functional alterations. Furthermore, many signalling molecules produced by astrocytes contribute to these processes. The aim of the present study was to investigate the influence of ethanol and its primary metabolite, acetaldehyde, on TNF-alpha and IL-6 production in a rat cortical astrocyte primary culture. We are the first to report that both ethanol and acetaldehyde can modulate TNF-alpha and IL-6 secretion from cultured astrocytes. Long-term exposure (7 days) to ethanol and acetaldehyde was more toxic than an acute (24 hours) exposure. However, both compounds showed a biphasic, hormestic effect on the IL-6 secretion after the acute as well as the long-term exposure, and the maximum stimulation was reached for 50-mM ethanol and 1-mM acetaldehyde after 7-day exposure. In contrast, both compounds reduced the TNF-alpha secretion, where the effect was concentration-dependent. The catalase inhibitor 2-amino-1,2,4 triazole significantly reduced the ethanol toxicity in the cultured astrocytes after the acute as well as the long-term exposure. In conclusion, both ethanol and acetaldehyde affect the production of IL-6 and TNF-alpha in cultured astrocytes. The effect depends on the concentration of the compounds and the duration of the exposure. Acetaldehyde is a more potent toxin than ethanol, and ethanol's toxicity in the brain is at least partially due to its primary metabolite, acetaldehyde.

The involvement of Smac/DIABLO, p53, NF-kB, and MAPK pathways in apoptosis of keratinocytes from perilesional vitiligo skin: Protective effects of curcumin and capsaicin

Oxidative stress has been suggested as the initial pathogenetic event in melanocyte degeneration in vitiligo. Our previous results indicate that keratinocytes from perilesional skin show the features of damaged cells. In the present study, biopsies were taken from the perilesional skin of 12 patients suffering from nonsegmental vitiligo. The intracellular pathways involved in keratinocyte damage and apoptosis and the antioxidant protection of curcumin and capsaicin in these cells were investigated. In keratinocytes from perilesional vitiligo skin, we observed high levels of activated p38, NF-kB p65 subunit, p53, and Smac/DIABLO proteins. In contrast, low levels of ERK phosphorylation were present. To investigate the relationship between these pathways, we used specific inhibitors and evaluated the alteration of each pathway. For the first time, our study demonstrates the pivotal role of p38 MAP kinase as an upstream signal of perilesional keratinocyte damage, and the important contribution of p38 and NF-kB on p53 accumulation. Curcumin and capsaicin also increase ERK phosphorylation, thus inhibiting apoptosis. Moreover, pretreatment with such natural antioxidants inhibited caspase activation, increased total antioxidant capacity, repressed intracellular ROS generation and lipid peroxidation, and improved mitochondrial activity. These results suggest that antioxidants might represent an alternative approach to protect against vitiligo progression.

Protective effects of platinum nanoparticles against UV-light-induced epidermal inflammation

Intracellular reactive oxygen species (ROS) and apoptosis play important roles in the ultraviolet (UV)-induced inflammatory responses in the skin. Metal nanoparticles have been developed to increase the catalytic activity of metals, which is because of the large surface area of smaller particles. Platinum nanoparticles (nano-Pt) protected by poly acrylic acid were manufactured by reduction with ethanol. A marked increase in ROS production was observed in UV-treated HaCaT keratinocytes cell lines, while a decrease in ROS production was observed in nano-Pt-treated cells. Pretreatment of the cells with nano-Pt also caused a significant inhibition of UVB- and UVC-induced apoptosis. Furthermore, we found that mice treated with nano-Pt gel prior to UV irradiation showed significant inhibition of UVB-induced inflammation and UVA-induced photoallergy compared to UV-irradiated control mice. These results suggest that nano-Pt effectively protects against UV-induced inflammation by decreasing ROS production and inhibiting apoptosis in keratinocytes.

Prophylactic effect of N-acetylcysteine against sodium fluoride-induced blood oxidative stress in mice

Ninety female Balb/c mice were used. The animals were allocated to evenly six groups. While the first group was maintained as control, Groups 3, 4, 5, and 6 were administered 750 ppm, 1500 ppm, 3000 ppm, and 6000 ppm of N-acetylcysteine, respectively, for a period of 15 days. After day 15, Groups 2-6 were administered sodium fluoride, containing 100 ppm fluoride in drinking water, for another 15 days. Plasma malondialdehyde (MDA) levels and erythrocyte superoksid dismutase (SOD) and catalase (CAT) activities were determined at the beginning of the trial and on days 15 and 30. According to the data obtained in the present study, N-acetylcysteine, when administered at the indicated doses, did not produce a significant alteration in any of the three parameters investigated. On the other hand, while the plasma MDA level was determined to have increased significantly, erythrocyte SOD and CAT activities were ascertained to have decreased significantly in the group, which was administered sodium fluoride alone on day 30. In the groups, which were administered N-acetylcysteine prior to sodium fluoride, however, it was observed that, after sodium fluoride administration, plasma MDA levels and erythrocyte SOD and CAT activities drew closer to the values of the control group.

Comparative study of the in vitro protective effects of several antioxidants on elongation factor 2 under oxidative stress conditions

One of the biochemical pathways affected by aging in all organisms is protein synthesis. Previous reports from our laboratory have indicated that the elongation step is specially affected by aging as a consequence of alterations in elongation factor-2 (eEF-2). In the present work, we studied in vitro the effectiveness of several individual nutritional antioxidants in protecting the levels of hepatic eEF-2 subjected to oxidative stress induced by cumene hydroperoxide. The in vitro system employed consisted of rat liver homogenates treated with cumene hydroperoxide. The antioxidants used in this study were lipoic acid, coenzyme Q10, tethrahydrofolic acid, and N-tert-butyl-alpha-phenylnitrone. The results indicate that the antioxidants have different capacities to prevent eEF-2 loss, folic acid being the most effective. A comparison between the antioxidants used and their potential pro-oxidant activity is also discussed, on the basis of the oxidative stress parameters measured.

Trace minerals status and antioxidant enzymes activities in calves with dermatophytosis

The aim of this study was to determine the levels of trace minerals Zn, Cu, and Se, the effect of dermatophytosis on the level of thiobarbituric acid reactive substances (TBARS) as an indicator of lipid peroxidation, the status of enzymatic and nonenzymatic antioxidants, and the relationship between the mentioned trace minerals and antioxidant defense system in calves with dermatophytosis. A total of 21 Holstein calves with clinically established diagnosis of dermatophytosis and an equal number of healthy ones were included in this study. Results showed that 81% of mycotic isolates were Trichophyton verrucosum, while 19% were Trichophyton mentagrophytes. The level of Zn, Cu, Se, and glutathione (GSH) and the activity of the antioxidant enzymes, glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) were significantly (P <or= 0.05) lower. The plasma level of TBARS was significantly (P <or= 0.05) higher in dermatophytic calves compared to healthy controls. SOD activity was fairly correlated with serum Cu and positively correlated with serum Zn in healthy control (r = 0.68, P <or= 0.05; r = 0.58, P <or= 0.05) and in calves affected with dermatophytosis (r = 0.73, P <or= 0.05; r = 0.55, P <or= 0.05), respectively. GSH-Px activity was highly correlated with whole blood selenium (r = 0.78, P <or= 0.05) in healthy control and dermatophytic subjects (r = 0.76, P <or= 0.05). Our results demonstrated that in dermatophytosis, the alteration in the antioxidant enzyme activities might be secondary to changes in their cofactor concentrations.

Vitamin E forms in Alzheimer's disease: a review of controversial and clinical experiences

Vitamin E is a collective term for eight naturally occurring compounds, four tocopherols (alpha-, beta-, gamma-, and delta-) and four tocotrienols (alpha-, beta-, gamma-, and delta-). Although it is the major form of vitamin E in US diets, gamma-tocopherol receives little attention when compared to alpha-tocopherol, which is generally found in supplements and most studied for its effects on progression of cognitive impairment. Many clinical trials had been conducted with vitamin E and neurodegenerative disorders, with controversial results, including a recent study which disproves the benefit of vitamin E for Mild Cognitive Impairment and Alzheimer's Disease. This study examined the alpha-tocopherol supplement instead of gamma-tocopherol. Gamma-tocopherol has been found to be more effective in scavenging free radicals and nitrogen oxygen species that cause inflammation; both of these are components of neurodegenerative disorders. Secondly, the use of alpha-tocopherol supplements significantly reduces serum gamma-tocopherol, and this may have important biological effects. Therefore, any potential health benefits of alpha-tocopherol supplements may be offset by deleterious changes in the bioavailability of other forms of tocopherols and tocotrienols. This might account for the null effects of alpha tocopherol supplementation in Mild Cognitive Impairment and Alzheimer's Disease.

Regulation of apoptosis-associated lysosomal membrane permeabilization

Lysosomal membrane permeabilization (LMP) occurs in response to a large variety of cell death stimuli causing release of cathepsins from the lysosomal lumen into the cytosol where they participate in apoptosis signaling. In some settings, apoptosis induction is dependent on an early release of cathepsins, while under other circumstances LMP occurs late in the cell death process and contributes to amplification of the death signal. The mechanism underlying LMP is still incompletely understood; however, a growing body of evidence suggests that LMP may be governed by several distinct mechanisms that are likely engaged in a death stimulus- and cell-type-dependent fashion. In this review, factors contributing to permeabilization of the lysosomal membrane including reactive oxygen species, lysosomal membrane lipid composition, proteases, p53, and Bcl-2 family proteins, are described. Potential mechanisms to safeguard lysosomal integrity and confer resistance to lysosome-dependent cell death are also discussed.

Antigenotoxic potential of Gymnema montanum leaves on DNA damage in human peripheral blood lymphocytes and HL-60 cell line

In this study we have evaluated the genoprotective effect of the ethanol extract of Gymnema montanum (GLEt) leaves in human peripheral blood lymphocytes and HL-60 cell line in vitro using the comet assay. DNA damage was induced by treating the cells with H(2)O(2) and methyl methane sulphonate (MMS). GLEt treatment effectively protected the lymphocytes and HL-60 cell line from H(2)O(2)-induced oxidative DNA damage in a dose-dependent manner whereas it was not effective against alkylative DNA damage caused by MMS. The global percent repair efficiency also showed that both pre- and post- GLEt treatment provided effective protection against H(2)O(2) induced DNA damage but not as effective against MMS. At 200 microg ml(-1) level, its repair capacity against H(2)O(2) induced DNA damage was comparable to that of vitamin-C (100 microM). Furthermore, exposure to GLEt reduced the formation of apoptotic cells caused by H(2)O(2), which was demonstrated by the decreased sub-G1-DNA content in cell cycle analysis and apoptotic frequencies of lymphocytes in an annexin-V binding assay. In addition, GLEt was found to have effective peroxide scavenging ability in dose-dependent manner. The protective efficiency of the extract was found to be directly proportional to its total phenolic content. The present study indicates that G. montanum leaves are a significant source of phytochemicals with antigenotoxic and antioxidant activity, and thus has potential therapeutic use.

A proteomics based approach to assessing the toxicity of bisphenol A and diallyl phthalate to the abalone (Haliotis diversicolor supertexta)

The contamination of marine ecosystems by endocrine disrupting compounds (EDCs) is of great concern. Protein expression profile maybe a good method to help us understand the molecular mechanisms of EDCs-toxicity to aquatic organisms. In this study, the abalone (Haliotis diversicolor supertexta), was selected as the target organism. Toxicological effects of two reference endocrine disruptors: diallyl phthalate (DAP, 50microgL(-1)) and bisphenol-A (BPA, 100microgL(-1)) were investigated after a three months static-renewal exposure on abalones using proteomics to analyze their hepatopancreas tissues. Some enzyme activity parameters of hepatopancreas extracts were also performed, including Na(+)-K(+)-ATPase, Ca(2+)-Mg(2+)-ATPase, peroxidase (POD) and malondialdehyde (MDA) production. After analyzing the proteomics profile of hepatopancreas by 2D gel electrophoresis, we found that 24 spots significantly increased or decreased at protein expression level (2-fold difference) in the 2D-maps from the treatment groups. Eighteen out of 24 protein spots were successfully identified by matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry (MALDI-TOF-MS). These proteins can be roughly categorized into diverse functional classes such as detoxification, oxidative stress, hormone regulating, cellular metabolism and innate immunity. In addition, the enzymatic results indicated that DAP/BPA exposure affected the oxidative stress status and the cellular homeostasis, which partly corroborated the proteomics' results. Taken together, these data demonstrate that proteomics is a powerful tool to provide valuable insights into possible mechanisms of toxicity of EDCs contaminants in aquatic species. Additionally, the results highlight the potential of abalone as a valuable candidate for investigating EDCs impacts on marine ecosystems.

Effect of anthocyanin-rich extract from black rice (Oryza sativa L. Japonica) on chronically alcohol-induced liver damage in rats

The study evaluated the protective effect of anthocyanin-rich extract from black rice (AEBR) on chronic ethanol-induced biochemical changes in male Wistar rats. Administration of ethanol (3.7 g/kg/day) to Wistar rats for 45 days induced liver damage with a significant increase (P < 0.05) of aspartate transaminase (AST), alanine transaminase (ALT), gamma glutamyl transferase (GGT) in the serum and the hepatic malondialdehyde (MDA) level. In contrast, administration of AEBR (500 mg/kg) along with alcohol significantly (P < 0.01) decreased the activities of liver enzymes (AST, ALT and GGT) in serum, the MDA levels and the concentrations of serum and hepatic triglyceride (TG) and total cholesterol (TCH). Rats treated with AEBR showed a better profile of the antioxidant system with normal glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and glutathione S-transferase (GST) activities. All these results were accompanied by histological observations in liver. The results demonstrate that AEBR has a beneficial effect in reducing the adverse effect of alcohol.

Simultaneous analysis of reactive oxygen species and reduced glutathione content in living cells by polychromatic flow cytometry

Reactive oxygen species (ROS) are continuously produced in the cell as a consequence of aerobic metabolism, and are controlled by several antioxidant mechanisms. An accurate measurement of ROS is essential to evaluate the redox status of the cell, or the effects of molecules with the pro-oxidant or antioxidant activity. Here we report a cytofluorimetric technique for measuring simultaneously, at the single-cell level, hydrogen peroxide and superoxide anion, reduced glutathione (a main intracellular antioxidant) and cell viability. The staining is performed with the fluorescent dyes 2',7'-dichlorodihydrofluorescein diacetate (H2DCFH-DA), hydroethidine (HE), monobromobimane (MBB) and TO-PRO-3. This analysis is possible with new-generation flow cytometers equipped with several light sources (in our case, four lasers and an UV lamp), which excite different fluorochromes. This approach is extremely useful to study the balance between ROS content and antioxidants in cells receiving different stimuli, and to analyze the relationship between oxidative stress and cell death.

The Clinical Application of Ozonetherapy

The reader may be eager to examine in which diseases ozonetherapy can be proficiently used and she/he will be amazed by the versatility of this complementary approach (Table 9 1). The fact that the medical applications are numerous exposes the ozonetherapist to medical derision because superficial observers or sarcastic sceptics consider ozonetherapy as the modern panacea. This seems so because ozone, like oxygen, is a molecule able to act simultaneously on several blood components with different functions but, as we shall discuss, ozonetherapy is not a panacea. The ozone messengers ROS and LOPs can act either locally or systemically in practically all cells of an organism. In contrast to the dogma that “ozone is always toxic”, three decades of clinical experience, although mostly acquired in private clinics in millions of patients, have shown that ozone can act as a disinfectant, an oxygen donor, an immunomodulator, a paradoxical inducer of antioxidant enzymes, a metabolic enhancer, an inducer of endothelial nitric oxide synthase and possibly an activator of stem cells with consequent neovascularization and tissue reconstruction.

Effect of short-term free Fatty acids elevation on mitochondrial function in skeletal muscle of healthy individuals

CONTEXT

Mitochondrial dysfunction has been proposed as an underlying mechanism in the pathogenesis of insulin resistance and type 2 diabetes mellitus.

OBJECTIVE

To determine whether mitochondrial dysfunction plays a role in the free fatty acid (FFA)-induced impairment in insulin action in skeletal muscle of healthy subjects.

DESIGN

Eleven lean normal glucose tolerant individuals received 8 h lipid and saline infusion on separate days with a euglycemic insulin clamp during the last 2 h. Vastus lateralis muscle biopsies were performed at baseline and after 6 h lipid or saline infusion. Inner mitochondrial membrane potential (Psi(m)) and mitochondrial mass were determined ex vivo by confocal microscopy.

RESULTS

Compared with saline infusion, lipid infusion reduced whole-body glucose uptake by 22% (P < 0.05). Psi(m) decreased by 33% (P < 0.005) after lipid infusion and the decrement in Psi(m) correlated with change in plasma FFA after lipid infusion (r = 0.753; P < 0.005). Mitochondrial content and morphology did not change after lipid infusion. No significant changes in genes expression, citrate synthase activity, and total ATP content were observed after either lipid or saline infusion.

CONCLUSIONS

Short-term physiological increase in plasma FFA concentration in lean normal glucose tolerant subjects induces insulin resistance and impairs mitochondrial membrane potential but has no significant effects on mitochondrial content, gene expression, ATP content, or citrate synthase activity.

Is Ozone Really a “Wonder Drug”?

Even if the reader has only browsed through the previous chapters, he ought to have received my feeling that ozone has an enormous therapeutic potential that, so far, has been either disregarded, if not obstructed by world medical authorities. Reasons for delaying the use of ozone are multiple: while quacks and inexpert ozonetherapists are at fault for poor work, other aspects such as commercial and pharmaceutical interests, prejudice, lack of knowledge and a myopic medical vision have done their best to block a substantial and rapid progress.

Neuroprotection in the newborn infant

Neonatal brain injury is an important cause of death and disability, with pathways of oxidant stress, inflammation, and excitotoxicity that lead to damage that progresses over a long period of time. Therapies have classically targeted individual pathways during early phases of injury, but more recent therapies such as growth factors may also enhance cell proliferation, differentiation, and migration over time. More recent evidence suggests combined therapy may optimize repair, decreasing cell injury while increasing newly born cells.

Antioxidant enzymes show adaptation to oxidative stress in athletes and increased stress in hemodialysis patients

The aim of the study is to compare oxidative stress in hemodialysis patients in controls and in rowers. The patients are a model of decreased antioxidant capacity, and the athletes (rowers) are a model of the highest antioxidant capacity due to their chronic adaptation to demanding training. Thirty-five subjects participated in the study, 9 patients with end-stage renal disease treated by hemodialysis, 12 healthy young subjects from the normal population, and 14 rowers. The antioxidant enzymes catalase, superoxide dismutase, and glutathione peroxidase, as well as non-transferrin-bound iron as a promoter of free radical damage, were determined. Blood analysis was taken in dialysis patients in the morning, before the dialysis procedure. There was significantly higher activity of catalase in dialysis patients (catalase 4.26 +/- 0.35 mkat/g Hb) compared to the controls (catalase 2.73 +/- 0.38 mkat/g Hb) and rowers (catalase 1.71 +/- 0.30 mkat/g Hb). Superoxide dismutase activity was significantly lower (10.42 +/- 1.46 microkat/g Hb) than in the controls (11.94 +/- 1.18 microkat/g Hb) and rowers (14.09 +/- 0.92 microkat/g Hb). There was no significant differences between glutathione peroxidase activities in the three groups. Superoxide dismutase and Se were higher in rowers than in dialysis patients (P < 0.05). The concentrations of both non-transferrin-bound iron and ferritin were significantly higher in dialysis patients. Hemodialysis patients might have increased oxidative stress, which is characterized by significantly higher erythrocyte enzyme activity of catalase and lower activity of superoxide dismutase. Top rowers had increased superoxide dismutase and glutathione peroxidase, perhaps because of adaptation during training, which was not the case in dialysis patients and controls.

Nrf2 and antioxidant defense against CYP2E1 toxicity

The transcription factor Nrf2 regulates the expression of important cytoprotective enzymes. Induction of CYP2E1 is one of the central pathways by which ethanol generates oxidative stress. CYP2E1 can be induced by ethanol and several low molecular mass chemicals such as pyrazole. This review discusses biochemical and toxicological effects of CYP2E1 and the effects of Nrf2 in modulating these actions of CYP2E1. Besides ethanol, CYP2E1 metabolizes and activates many other toxicologic important compounds. One approach to try to understand the basic effects and actions of CYP2E1 was to establish HepG2 cell lines that constitutively express human CYP2E1. Ethanol, polyunsaturated fatty acids and iron were toxic to the HepG2 cells, which express CYP2E1 (E47 cells) but not control C34HepG2 cells, which do not express CYP2E1. Toxicity was associated with enhanced oxidant stress and could be prevented by antioxidants and potentiated if glutathione was removed. The E47 cells had higher glutathione levels and a twofold increase in catalase, cytosolic and microsomal glutathione transferase, and heme oxygenase-1 than control HepG2 cells due to activation of their respective genes. These activations were prevented by antioxidants, suggesting that reactive oxygen species generated by CYP2E1 were responsible for the upregulation of these antioxidant genes. This upregulation may reflect an adaptive mechanism to remove CYP2E1-derived oxidants. Increases in Nrf2 protein and mRNA were observed in livers of chronic alcohol-fed mice or rats and of pyrzole-treated rats or mice, conditions known to elevate CYP2E1. E47 cells showed increased Nrf2 mRNA and protein expression compared with control HepG2 C34 cells. Upregulation of antioxidant genes in E47 cells is dependent on Nrf2 and is prevented by siRNA-Nrf2. Blocking Nrf2 by siRNA-Nrf2 decreases glutathione and increases reactive oxygen species and lipid peroxidation, resulting in decreased mitochondrial membrane potential and loss of cell viability of E47 cells, but not C34 cells. Nrf2 is activated and levels of Nrf2 protein and mRNA are increased when CYP2E1 is elevated. These results suggest that Nrf2 plays a key role in the adaptive response against increased oxidative stress caused by CYP2E1 in the HepG2 cells. However, it is not clear whether Nrf2 is protective against CYP2E1 toxicity in vivo as pyrazole which elevates CYP2E1 in wild-type mice did not elevate CYP2E1 in Nrf2 knockout mice, although pyrazole produced toxicity in the Nrf2 knockout mice.

Adaptation to oxidative stress, chemoresistance, and cell survival

The discovery of some additional properties and functions of reactive oxygen species (ROS), beyond their toxic effects, provides a novel scenario for the molecular basis and cell regulation of several pathophysiologic processes. ROS are generated by redox-sensitive, prosurvival signaling pathways and function as second messengers in the transduction of several extracellular signals. A complex intracellular redox buffering network has developed to adapt and protect cells against the dangerous effects of oxidative stress. However, pathways involved in ROS-adaptive response may also play a critical role in protecting cells against cytotoxic effects of anticancer agents, thus supporting the hypothesis of a correlation between adaptation/resistance to oxidative stress and resistance to anticancer drugs. This review summarizes the main systems involved in the adaptive responses: an overview on the pathophysiologic relevance of mitochondria on redox-sensitive transcription factors and genes and main antioxidant networks in tumor cells is provided. One of the major aims is to highlight the adaptive mechanisms and their interplay in the intricate connection between oncogenic signaling, oxidative stress, and chemoresistance. Clarification of these mechanisms has tremendous application potential, in terms of developing novel molecular-targeted anticancer therapies and innovative strategies for rational combination of these agents with chemotherapeutic or tumor-specific biologic drugs.

Purification, Characterization, and Effect of Thiol Compounds on Activity of the Erwinia carotovora L-Asparaginase

L-asparaginase was extracted from Erwinia carotovora and purified by ammonium sulfate fractionation (60–70%), Sephadex G-100, CM cellulose, and DEAE sephadex chromatography. The apparent Mr of enzyme under nondenaturing and denaturing conditions was 150 kDa and 37 ± 0.5 kDa, respectively. L-asparaginase activity was studied in presence of thiols, namely, L-cystine (Cys), L-methionine (Met), N-acetyl cysteine (NAC), and reduced glutathione (GSH). Kinetic parameters in presence of thiols (10–400 μM) showed an increase in V_max values (2000, 2223, 2380, 2500, and control 1666.7 μmoles mg⁻¹min⁻¹) and a decrease in K_m values (0.086, 0.076, 0.062, 0.055 and control 0.098 mM) indicating nonessential mode of activation. K_A values displayed propensity to bind thiols. A decrease in V_max/K_m ratio in concentration plots showed inverse relationship between free thiol groups (NAC and GSH) and bound thiol group (Cys and Met). Enzyme activity was enhanced in presence of thiol protecting reagents like dithiothreitol (DTT), 2-mercaptoethanol (2-ME), and GSH, but inhibited by p-chloromercurybenzoate (PCMB) and iodoacetamide (IA).

Total antioxidant performance is associated with diet and serum antioxidants in participants of the diet and physical activity substudy of the Jackson Heart Study

Total antioxidant performance (TAP) measures antioxidant capacities in both hydrophilic and lipophilic compartments of serum and interactions known to exist between them. Our objective was to assess TAP levels in a subset of Jackson Heart Study (JHS) participants and to examine associations with dietary and total (diet + supplement) intakes of alpha-tocopherol, gamma-tocopherol (diet only), beta-carotene, vitamin C, fruit, vegetables, and nuts, and serum concentrations of alpha-tocopherol, gamma-tocopherol, and beta-carotene. We conducted a cross-sectional analysis of 420 (mean age 61 y; 254 women) African American men and women participating in the Diet and Physical Activity Sub-Study of the JHS in Jackson, Mississippi. In multivariate-adjusted models, we observed positive associations between total alpha-tocopherol, total and dietary beta-carotene, and total vitamin C intakes and TAP levels (P-trend < 0.05). Positive associations were also observed for vegetable, fruit, and total fruit and vegetable intakes (P-trend < 0.05). For serum antioxidant nutrients, alpha-tocopherol but not beta-carotene was associated with serum TAP levels. There were inverse associations for serum gamma-tocopherol and TAP levels. Associations for alpha-tocopherol were seen at intake levels much higher than the current Recommended Dietary Allowance. It may, therefore, be prudent to focus on increasing consumption of fruit, vegetables, nuts, and seeds to increase total antioxidant capacity.

Calorie restriction and the exercise of chromatin

Since the earliest stages of evolution, organisms have faced the challenge of sensing and adapting to environmental changes for their survival under compromising conditions such as food depletion or stress. Implicit in these responses are mechanisms developed during evolution that include the targeting of chromatin to allow or prevent expression of fundamental genes and to protect genome integrity. Among the different approaches to study these mechanisms, the analysis of the response to a moderate reduction of energy intake, also known as calorie restriction (CR), has become one of the best sources of information regarding the factors and pathways involved in metabolic adaptation from lower to higher eukaryotes. Furthermore, responses to CR are involved in life span regulation-conserved from yeast to mammals-and therefore have garnered major research interest. Herein we review current knowledge of responses to CR at the molecular level and their functional link to chromatin.

The ozone paradox: ozone is a strong oxidant as well as a medical drug

After five decades characterized by empiricism and several pitfalls, some of the basic mechanisms of action of ozone in pulmonary toxicology and in medicine have been clarified. The present knowledge allows to understand the prolonged inhalation of ozone can be very deleterious first for the lungs and successively for the whole organism. On the other hand, a small ozone dose well calibrated against the potent antioxidant capacity of blood can trigger several useful biochemical mechanisms and reactivate the antioxidant system. In detail, firstly ex vivo and second during the infusion of ozonated blood into the donor, the ozone therapy approach involves blood cells and the endothelium, which by transferring the ozone messengers to billions of cells will generate a therapeutic effect. Thus, in spite of a common prejudice, single ozone doses can be therapeutically used in selected human diseases without any toxicity or side effects. Moreover, the versatility and amplitude of beneficial effect of ozone applications have become evident in orthopedics, cutaneous, and mucosal infections as well as in dentistry.

Role of oxidative stress in alcohol-induced liver injury

Reactive oxygen species (ROS) are highly reactive molecules that are naturally generated in small amounts during the body's metabolic reactions and can react with and damage complex cellular molecules such as lipids, proteins, or DNA. Acute and chronic ethanol treatments increase the production of ROS, lower cellular antioxidant levels, and enhance oxidative stress in many tissues, especially the liver. Ethanol-induced oxidative stress plays a major role in the mechanisms by which ethanol produces liver injury. Many pathways play a key role in how ethanol induces oxidative stress. This review summarizes some of the leading pathways and discusses the evidence for their contribution to alcohol-induced liver injury. Special emphasis is placed on CYP2E1, which is induced by alcohol and is reactive in metabolizing and activating many hepatotoxins, including ethanol, to reactive products, and in generating ROS.

Protective effect of rutin on the ischemia/reperfusion induced damage in rat kidney

Reactive oxygen species (ROS) are suggested to participate in ischemia/reperfusion (I/R) injury in the kidney. This study was designed to investigate the effect of rutin, a bioflavonoid, in I/R induced renal injury. Wistar albino rats were unilaterally nephrectomized, and 2 wk later they were subjected to 45 min of left renal pedicle occlusion followed by 3h of reperfusion. Either rutin (1g/kg) or saline was administrated (i.p.) 1h prior to ischemia. At the end of the reperfusion period, kidney samples were taken for determination of renal malondialdehyde (MDA) and glutathione (GSH) levels, manganese-superoxide dismutase (MnSOD) activity and histological examination. Serum creatinine, blood urea nitrogen (BUN), and lactate dehydrogenase (LDH) concentrations were measured for the evaluation of renal function. I/R caused a significant decrease in GSH level and MnSOD activity, which was accompanied by a significant increase in MDA level of kidney tissues. Similarly, serum BUN and creatinine levels, as well as LDH were elevated in the I/R group compared with the control group. Pretreatment of rats with rutin (1g/kg/ i.p.) significantly attenuated renal dysfunction, reduced elevated MDA levels, and restored the depleted MnSOD activity and GSH levels. These beneficial changes in the biochemical parameters were also associated with parallel changes in histopathological appearance. These findings suggest that ROS play a causal role in I/R induced renal injury, and that rutin exerts renal-protective effects, probably by inhibiting ROS and antioxidant activities.

Carotenoids provide the major antioxidant defence in the globally significant N2-fixing marine cyanobacterium Trichodesmium

Photosynthetic oxygen-evolving microorganisms contend with continuous self-production of molecular oxygen and reactive oxygen species. The deleterious effects of reactive oxygen species are exacerbated for cyanobacterial nitrogen-fixers (diazotrophs) due to the innate sensitivity of nitrogenase to oxygen. This renders incompatible the processes of oxygen-evolving photosynthesis and N-fixation. We examined total antioxidative potential of various diazotrophic and non-diazotrophic cyanobacteria. We focused on Trichodesmium spp., a bloom-forming marine diazotroph that contributes significantly to global nitrogen fixation. Among the species tested, Trichodesmium possessed the highest antioxidant activity. Moreover, while proteins constituted the dominant antioxidative component of all other cyanobacteria tested, Trichodesmium was unique in that small-molecule natural products provided the majority of antioxidant activity, while proteins constituted only 13% of total antioxidant activity. Bioassay-guided fractionation followed by high-performance liquid chromatography profiling of antioxidant purified fractions identified the highly potent antioxidant all-trans-β-carotene, and small amounts of 9-cis-β-carotene and retinyl palmitate. Search of the Trichodesmium genome identified protein sequences homologous to key enzymes in the β-carotene to retinyl palmitate biosynthetic pathway, including 33-37% identity to lecithin retinol acyltransferase. The present study demonstrates the importance of carotenoids in Trichodesmium's arsenal of defensive compounds against oxidative damage and protection of nitrogenase from oxygen and its radicals.

Free radical scavenging activity of Lactobacillus fermentum in vitro and its antioxidative effect on growing-finishing pigs

AIMS

To evaluate the free radical-scavenging capacity of Lactobacillus fermentum and its effects on antioxidant enzyme levels in finishing pigs.

METHODS AND RESULTS

The free radical-scavenging activity of Lact. fermentum was analysed in vitro. The tested Lactobacillus showed a high scavenging ability against DPPH (1,1-diphenyl-2-picrylhydrazyl), superoxide and hydroxyl radicals which was dose dependent. Subsequently, 108 crossbred pigs weighing 20.67 BW, were allotted to dietary treatments including a basal diet or the basal diet supplemented with either aureomycin or 10.2 x 10(7) Lact. fermentum CFU g(-1) diet. Supplementation of Lact. fermentum increased total antioxidant capacity (P < 0.01) in serum from 50 kg pigs, while serum superoxide dismutase (P = 0.01) and glutathione peroxidase (P < 0.01) increased, and malondialdehyde levels decreased (P < 0.01) in 90 kg pigs. Hepatic catalase (P = 0.04), muscle superoxide dismutase (P < 0.01) and copper-zinc-superoxide dismutase were enhanced (P = 0.01), whereas malondialdehyde levels were reduced (P = 0.05) by Lact. fermentum.

CONCLUSIONS

The free radical-scavenging capacity of Lact. fermentum was dose dependent and its supplementation improved the antioxidant status of pigs.

SIGNIFICANCE AND IMPACT OF THE STUDY

Lactobacillus fermentum could be used to alleviate oxidative stress and increase pig performance and improve pork quality.

The wanderings of a free radical

In my career I have moved from chemistry to biochemistry to plant science to clinical chemistry and back again (in a partial way) to plants. This review presents a brief history of my research achievements (ascorbate-glutathione cycle, role of iron in oxidative damage and human disease, biomarkers of free radical damage, and studies on atherosclerosis and neurodegeneration) and how they relate to my research activities today. The field of free radicals/other reactive species/antioxidants underpins all of modern Biology. These agents helped to drive human evolution and the basic principles of the field are repeatedly found to be relevant in other research areas. It was an exciting field when I started some 40 years ago, and it still is today, but some major challenges must be faced.

Antioxidant effect of propolis against exposure to propetamphos in rats

In the present study, each group comprised six animals, and a total of 30 female. Wistar Albino rats weighing 200-250g were used. The first group served as the control group. Group 2 received propolis at a concentration of 100mg/kgbw/day in drinking water. Groups 3 and 4 were administered propetamphos at doses of 7.5 and 15.0mg/kgbw/day, respectively, in drinking water. Group 5 was treated with propetamphos at a dose of 15.0mg/kgbw/day, in association with 100mg/kgbw/day propolis in drinking water. Treatment was continued for 28 days, and at the end of this period, blood and tissue (liver, kidney and brain) samples were collected. Plasma and tissue MDA levels and erythrocyte and tissue SOD, CAT, and GSH-Px activities were measured. In conclusion, the administration of propolis was concluded to exhibit antiradical and antioxidant effect, and thereby to result in the alleviation of oxidative stress.

Pancreas beta-cells morphology, liver antioxidant enzymes and liver oxidative parameters in alloxan-resistant and alloxan-susceptible Wistar rats: a viable model system for the study of concepts into reactive oxygen species

The aim of this study was to investigate biochemical and antioxidant parameters in alloxan-resistant (ALR) and alloxan-susceptible (ALS) rats. Diabetes was induced in 60-day-old male Wistar rats by a single intraperitonial injection of alloxan (AL, 150 mg/kg). Ten days after induction, a group of rats showed a significant decrease in glycemia. This group was named alloxan-resistant group. Susceptible rats showed a remarkable increase in the plasma lipid content, blood glucose and HbA1. Glycogen content in the liver decreased significantly in the ALS group (2.08 +/- 0.41 mg%) compared with ALR group (4.22 +/- 0.18). Aspartate aminotransferase and alanine aminotransferase activities were quantified in the plasma. Interestingly, ALR rats showed a decrease in both activities (42.1 +/- 6.11 and 21.7 +/- 5.54 U/mL) when compared with ALS rats (59.1 +/- 6.55 and 58.1 +/- 7.28 U/mL). The TBARS index was significantly increased in the ALS liver (0.38 +/- 0.08 nm/mg protein) when compared with the ALR liver (0.18 +/- 0.04). Superoxide dismutase and catalase activities in the ALR (230 +/- 13 and 131 +/- 15 U/mg protein) liver showed a marked increase when compared with the ALS liver (148 +/- 13 and 68 +/- 5 U/mg protein). The immunohistochemical and hematoxilin-eosin analysis also revealed that pancreatic islets of ALR rats display a different morphology amongst the groups. These results suggest an increased regenerative or recovery process in the ALR rat pancreatic islets and an increased hepatic antioxidant defenses in these group of alloxan-resistant rats.

Protective effects against H2O2-induced damage by enzymatic hydrolysates of an edible brown seaweed, sea tangle (Laminaria japonica)

Enzymatic hydrolysates of Laminaria japonica were evaluated for antioxidative activities using hydroxyl radical scavenging activity and protective effects against H(2)O(2)-induced DNA and cell damage. In addition, activities of antioxidative enzymes, including catalase, glutathione peroxidase, and glutathione S-transferase, of the enzymatic hydrolysates from L. japonica were also estimated. L. japonica was first enzymatically hydrolyzed by seven carbohydrases (Dextrozyme, AMG, Promozyme, Maltogenase, Termamyl, Viscozyme, and Celluclast [all from Novo Co., Novozyme Nordisk, Bagsvaerd, Denmark]) and five proteinases (Flavourzyme, Neutrase, Protamex, Alcalase [all from Novo Co.], and pancreatic trypsin). The hydroxyl radical scavenging activities of Promozyme and pancreatic trypsin hydrolysates from L. japonica were the highest as compared to those of the other carbohydrases and proteinases, and their 50% inhibitory concentration values were 1.67 and 317.49 mug/mL, respectively. The pancreatic trypsin hydrolysates of L. japonica exerted a protective effect on H(2)O(2)-induced DNA damage. We also evaluated the protective effect on hydroxyl radical-induced oxidative damage in PC12 cells via propidium iodide staining using a flow cytometer. The AMG and pancreatic trypsin hydrolysates of L. japonica dose-dependently protected PC12 cells against cell death caused by hydroxyl radical-induced oxidative damage. Additionally, we analyzed the activity of antioxidative enzymes such as catalase, glutathione peroxidase, and the phase II biotransformation enzyme glutathione S-transferase in L. japonica-treated cells. The activity of all antioxidative enzymes was higher in L. japonica-treated cells compared with the nontreated cells. These results indicate that enzymatic hydrolysates of L. japonica possess antioxidative activity.