Total Thiol Groups Research Articles

Versatile Probes for the Selective Detection of Vicinal‐Dithiol‐Containing Proteins: Design, Synthesis, and Application in Living Cells

Endogenous vicinal-dithiol-containing proteins (VDPs) that have two thiol groups close to each other in space play a significant importance in maintaining the cellular redox microenvironment. Approaches to identify VDPs mainly rely on monitoring the different concentration of monothiol and total thiol groups or on indirect labeling of vicinal thiols by using p-aminophenylarsenoxide (PAO). Our previous work has reported the direct labeling of VDPs with a highly selective receptor PAO analogue, which could realize fluorescence detection of VDPs directly in living cells. Herein, we developed a conjugated approach to expand detectable tags to nitrobenzoxadiazole (NBD), fluorescein, naphthalimide, and biotin for the synthesis of a series of probes. Different linkers have also been introduced toward conjugation of VTA2 with these functional tags. These synthesized flexible probes with various features will offer new tools for the potential identification and visualization of vicinal dithiols existing in different regions of VDPs in living cells. These probes are convenient tools for proteomics studies of various disease-related VDPs and for the discovery of new drug targets.

The patients with clinically isolated syndrome and relapsing remitting multiple sclerosis show different levels of advanced protein oxidation products and total thiol content in plasma and CSF

Advanced oxidation protein products (AOPP) and total thiol (SH) groups levels in plasma and CSF were studied in a cohort of 50 clinically isolated syndrome (CIS) and 57 relapsing remittent multiple sclerosis (RRMS) patients related to 20 control group (CG) patients’ values. The obtained results were compared regarding patients demographic, biochemical, clinical (EDSS) and MRI features (total T2 weighted lesions number and Gd enhancement lesion volume).Plasma and CSF AOPP levels in CIS and RRMS patients were higher than those in CG, while SH groups showed lower values compared to CG (p<0.05). Both parameters were higher in CIS than in RRMS patients (p<0.05). Related to EDSS median range, all patients were divided into those with slight or mild and those with severe clinical presentation. AOPP and SH group changes were more pronounced in both, CIS and RRMS patients with higher, compared to those with lower EDSS (p<0.05). AOPP, SH group levels and EDSS positive correlations were observed in both study groups (p<0.01). Both parameters showed the same approach regarding the median range of total T2 weighted lesions and Gd enhancement lesion volume mean values (p<0.05), but no correlation was found between AOPP and SH levels and these patients radiological characteristics (p>0.01).The data support the fact that oxidative stress is always involved in CIS and RRMS pathophysiology, but not always as a disease determinant dependent on its intensity, which might be important for new therapeutic strategies based on antioxidant approach in those patients.

Antihyperglycemic and Antioxidant Activity of Crocin in Streptozotocin-Induced Diabetic Rats

The aim of the present study was to investigate the antihyperglycemic and protective potential of crocin, a pharmacologically active constituent of Crocus sativus L., in streptozotocin-induced diabetic rats. Rats were administered crocin intraperitoneally at doses of 15, 30, and 60 mg/kg of body weight for 6 weeks. The levels of thiobarbituric acid reactive substance (TBARS) and total thiol (SH) groups were measured in the liver and kidney at the end of 6 weeks. Under our experimental conditions, crocin at a dose of 60 mg/kg was found to significantly reduce the blood glucose level in diabetic animals. In addition, there was a significant increase in TBARS levels and decreased total thiol concentrations in the liver and kidney of diabetic animals. Crocin, at doses of 30 and 60 mg/kg, appears to exert an antioxidative activity demonstrated by a lowering of lipid peroxidation levels in these organs. In conclusion, our findings suggest that crocin has the hypoglycemic and antioxidative properties in streptozotocin-induced diabetes and it may be useful in the management of diabetic patients.

Oxidative stress in the gill tissues of goldfishes (Carassius auratus) parasitized by Dactylogyrus spp.

The aim of this study was to investigate the status of oxidative stress in the gill tissues of goldfishes (Carassius auratus) parasitized by Dactylogyrus spp. We therefore compared the concentrations of malondialdehyde (MDA) and total thiol groups in the gill tissues of parasitized and non- parasitized goldfishes. 15 goldfishes parasitized by Dactylogyrus spp. along with 15 non-parasitized goldfishes were selected for the study. A significant increase in MDA concentration (P<0.01) and a significant decrease in total thiol groups in the parasitized group, were observed when compared to the non- parasitized group. This is the first study which evaluates the effect of Dactylogyrus spp. on the oxidative stress status of goldfish. The results of the present study revealed that parasitized goldfishes showed more severe oxidative stress and lipid peroxidation than non- parasitized fishes and enhanced lipid peroxidation may be linked to gill damage in goldfishes parasitized by Dactylogyrus spp.

The Role of Xanthine Oxidase in Hemodialysis-Induced Oxidative Injury: Relationship with Nutritional Status

The role of xanthine oxidase (XOD) in patients undergoing chronic hemodialysis treatment (HD) is poorly understood. Geriatric nutritional risk index (GNRI) ≤ 90 could be linked with malnutrition-inflammation complex syndrome. This study measured XOD, myeloperoxidase (MPO), superoxide dismutase (SOD), lipid hydroperoxides, total free thiol groups, and advanced oxidation protein products (AOPP) in 50 HD patients before commencing (pre-HD) and immediately after completion of HD session (post-HD) and in 22 healthy controls. Pre-HD serum hydroperoxides, AOPP, XOD, and SOD were higher and total thiol groups were lower in patients than in controls (P < 0.05, resp.). Compared to baseline values, serum MPO activity was increased irrespective of GNRI status. Serum XOD activity was increasing during HD treatment in the group with GNRI ≤ 90 (P = 0.030) whilst decreasing in the group with GNRI > 90 (P = 0.002). In a multiple regression analysis, post-HD serum XOD activity was independently associated with GNRI ≤ 90 (β ± SE: 0.398 ± 0.151; P = 0.012) and HD vintage (β ± SE: −0.349 ± 0.139; P = 0.016). These results indicate that an upregulated XOD may be implicated in HD-induced oxidative injury contributing to accelerated protein damage in patients with GNRI ≤ 90.

Protective Effect of Myricetin on Proteins and Lipids of Erythrocytes Membranes

Myricetin (3, 5, 7-Trihydroxy -2- (3, 4, 5-trihydroxyphenyl) - 4-chromenone), a naturally occurring flavonol, is a potent scavenger of reactive oxygen species (ROS) and effectively prevent erythrocyte oxidation. The protective effect of myricetin on proteins and lipids of erythrocytes membranes was investigated. Erythrocytes membranes were subjected to oxidative stress by incubating them with 10 −5 M tert-butylhydroperoxide; this caused a significant increase in membrane protein carbonyl group content and membrane lipid peroxides while caused a significant decrease of membrane total thiol group and Na + , K + -ATPase activity. The presence of myricetin in micromolar concentration in the incubation medium decreased significantly protein carbonylation, lipid peroxidation and caused an increase in total thiol group and Na + , K + ATP-ase activity.

Apigenin-induced apoptosis in A375 and A549 cells through selective action and dysfunction of mitochondria

We isolated apigenin (5,7,4'-trihydroxy flavone) from ethanolic extract of Lycopodium clavatum (LC) used as a homeopathic mother tincture for treatment of various diseases. We assessed the anticancer potentials of the compound using human malignant melanoma cell line A375 and a lung carcinoma cell line A549 and focussed on its putative molecular mechanism of action on apoptosis induction. We examined the cytotoxicity of apigenin in both cancer cells and normal peripheral blood mononuclear cells (PBMC). A375 cells were more prone to apigenin-induced apoptosis, as compared with A549 cells after 24 h of treatment, while PBMC showed little or no cytotoxicity to apigenin. We also evaluated the effects of apigenin on interaction with DNA by comparative analysis of circular dichroism spectral data and melting temperature profiles (Tm) of calf thymus DNA (CT-DNA) treated with or without apigenin. Reactive oxygen species (ROS) accumulation in mitochondria, super-oxide dismutase and total thiol group (GSH) activities were also analyzed. The apoptotic process involved mitochondrial pathway associated with apigenin-DNA interaction, DNA fragmentation, ROS accumulation, cytochrome c (cyt c) release and mitochondrial transmembrane potential depolarization, Bax, caspase 3, 9, PARP, up-regulation, Bcl-2 down-regulation and down-regulation of cyt c in the mitochondrial fraction. Results of mitochondrial inner membrane swelling measurements, intracellular ADP/ATP ratio and ATPase activity showed that in A549 cells, apigenin did not appear to directly target the mitochondrial oxidative phosphorylation system but rather acted at an upstream step to activate the mitochondrial apoptotic pathway. However, apigenin could directly target and impair mitochondrial function in A375 cells by breaking down their oxidative phosphorylation system. Collectively, these results suggest that apigenin exhibits anticancer potential in A375 and A549 cells that may be mediated through DNA interaction, damage and mitochondrial dysfunction either by direct or indirect action on mitochondrial oxidative phosphorylation system.

969 Antitumor Activity of NPS-1034, a Synthetic MET and AXL Inhibitor, in Lung Cancer Cells With Resistance to EGFR Tyrosine Kinase Inhibitors by MET or AXL Activation

an angiogenic phenotype by changing the local equilibrium between positive and negative regulators of angiogenesis, starts to grow rapidly and becomes clinically detectable, also to identify if the free radicals of oxygen plays an important role in the signaling pathway for the angiogenic transformation. Materials and Methods: We use RS1 experimental hepatoma bearing rats treated with Bevacizumab 5mg/body weight, weakly for 3 months and in this dynamics we determine the cell apoptosis by flow cytometry measurement and also the free radical of oxygen production by biochemical assays (lipid peroxidation, total thiol groups and the ability of plasma to reduce the iron). Results: Our results show a decrease of free radical production with 15%, 23% and 29% during the treatment suggesting the inhibition of the new blood vessel formation and the oxygen apport comparative to the untreated group. The histograms type graphics representing the DNA quantity distribution and the total cell number obtained by apoptosis measurement indicate an increase of apoptotic status with 9, 12%, 20, 14% and 31, 15% during the three month treatment. Conclusions: The anti-angiogenic treatment induces apoptosis − possiblemediated by free radicals of oxygen in a concentration dependent manner. When the reactive oxygen species are in a small concentration they can initiate the cell phenotype transformation to an angiogenic form, and when there is an increase of oxygen reactive species it is optimal to administer a targeted anti-angiogenic treatment to induce the tumoral cells apoptosis.

Structural Changes Imposed on Whey Proteins by UV Irradiation in a Continuous UV Light Reactor

The objective of this study was to investigate the structural changes of whey proteins during exposure in a continuous-flow UV reactor. Varying UV irradiation dosages were obtained by controlling the flow rate and the mixing speed. Whey protein isolate (WPI) solutions at concentrations of 1% and 5% (w/v) were circulated at flow rates ranging from 30 to 800 mL·min(-1), and changes in physicochemical properties of the proteins were investigated. Intrinsic fluorescence spectra and surface hydrophobicity measurements suggested changes in the tertiary structure of the proteins with UV exposure. The UV treatment also increased the concentration of total and accessible thiol groups in 1% WPI solutions, while no change was measured in 5% WPI solutions. Size-exclusion chromatography demonstrated the formation of UV-induced aggregates and oxidation products (N-formylkynurenine and dityrosine) of aromatic amino acids. Furthermore, the UV-induced changes in protein conformation increased the susceptibility of whey proteins to pepsin hydrolysis.

Antioxidant potential of different melatonin-loaded nanomedicines in an experimental model of sepsis

Oxidative stress has been shown to play a major role in the complex pathophysiological processes leading to organ failure during sepsis. The aim of the present research was to evaluate the effect of different melatonin nanoparticle (NP) carriers in an experimental animal model of sepsis. Poly-D,L-lactide-co-glycolide (PLGA [NP-A]) and polyethylene glycol-co-(poly-D,L-lactide-co-glycolide) (PLGA-PEG [NP-B]) were used to obtain melatonin-loaded nanocarriers (10 mg/kg). Oxidative stress was measured in tissue homogenates by measuring heme oxygenase-1 (HO-1) expression, total thiol groups and lipid hydroperoxides (LOOH). In vitro NPs showed a long lag time followed by a controlled release of melatonin. All the different melatonin formulations restored total thiol group levels to those of controls in all the examined organs, with no significant changes among them. Both melatonin NP formulations significantly decreased LOOH levels when compared with sepsis vehicle animals. The stealth formulation NP-B was able to produce a more significant reduction in LOOH levels in the heart, lung and liver when compared with NP-A. No significant changes were observed between the two NP formulations in the kidney. Interestingly, HO-1 expression was differently affected following treatment with various melatonin formulations. The NP-B formulation was more effective in inducing HO-1 protein compared with free melatonin and NP-A, with the exception of the kidney. Taken together, our results show that melatonin possesses a significant antioxidant activity during sepsis and that it is possible to improve this ability by delivering the compound with specific drug delivery systems.

Comparison of oxidative stress biomarkers in renal tissues of d-galactose induced, naturally aged and young rats

Ageing of kidneys is a clinical health issue of the society. Age-related renal insufficiency has important implications due to impaired redox homeostasis. We examined protein, DNA and lipid oxidation biomarkers as well as protein-bound sialic acid (SA) in the kidney tissues of D-galactose induced ageing rats, naturally aged rats and their corresponding young control group. Intraperitoneal injection of D-galactose (60 mg/kg/day) for 6 weeks to young male Sprague-Dawley rats (20-week-old) was used to establish mimetic ageing model. In this study, we investigated the levels of protein carbonyl groups (PCO), various thiol fractions such as total thiol groups (T-SH), protein (P-SH) and non-protein thiol groups (NP-SH), lipid oxidation parameters such as lipid hydroperoxides (LHP) and malondialdehyde (MDA), SA and 8-hydroxy-2'deoxyguanosine (8-OHdG) parameters for comparison of naturally aged, induced aged and young rats. In D-galactose induced aged group, PCO, LHP, MDA, and 8-OHdG concentrations were significantly higher than young control group, whereas T-SH, P-SH levels were significantly lower than the young rats. In addition, NP-SH and SA concentrations were similar between the mimetic ageing and young control groups. In naturally ageing rats, PCO and MDA levels were significantly higher, whereas T-SH, P-SH, NP-SH concentrations were low compared to young controls. On the other hand, SA and 8-OHdG levels were not different between the naturally ageing group and the young control group. Our results demonstrated that the rats in the mimetic ageing group, have significant similarities with the naturally aged rats in terms of impaired redox homeostasis and can be used as a reliable animal model for renal ageing.

Insulin-induced hypoglycemia and stress oxidative state in healthy people

The purpose of this study is to assess the immediate effects of insulin-induced hypoglycemia on the natural antioxidant superoxide dismutase activity, malondialdehyde concentration, total antioxidative capacity and total thiol group concentration in young healthy subjects. In this clinical trial, 16 healthy men with the mean age of 29.3 ± 5.3 years (range 21-39 years) became volunteers to participate the study. Hypoglycemia was induced by intravenous administration of regular insulin 0.1 U/kg. Before and after inducing hypoglycemia, SOD activity was determined in red blood cells, whereas the MDA concentration was determined by thiobarbituric acid reactive substance method, total thiol groups by high-performance liquid chromatography method and total antioxidant capacity by ferric reducing/antioxidant power. A significant increase was seen in the TBARS levels following insulin-induced hypoglycemia (0.19 ± 0.07 vs. 0.38 ± 0.16 nmol/g, P < 0.001), while a significant decrement occurred in the antioxidant power (FRAP value) (321.4 ± 63.4 vs. 231.4 ± 57.5, P < 0.001), total thiol concentration (2.3 ± 0.8 vs. 1.3 ± 0.5, P = 0.001) and SOD enzyme activity (29.4 ± 8.2 vs. 23.1 ± 6.1, P < 0.001) subsequent the hypoglycemia with insulin.

Effect of selenium pre-treatment on plasma antioxidant vitamins A (retinol) and E (α-tocopherol) in static magnetic field-exposed rats

In the present study, we evaluate the effect of the co-exposure to static magnetic field (SMF) and selenium (Se) on the antioxidant vitamins A and E levels and some other parameters of oxidative stress in rat. Sub-acute exposure of male adult rats to a uniform SMF (128 mT, 1 h/day during 5 consecutive days) increased plasma activity of glutathione peroxidase (+35%) but decreased α-tocopherol (-67%) and retinol levels (-41%). SMF exposure failed to alter the plasmatic thiobarbituric acid-reactive species (TBARs), total thiol groups and selenium concentrations. Sub-chronic administration of Se (Na(2)SeO(3), 0.2 mg/L, for 30 consecutive days, per os) ameliorated the antioxidant capacities in SMF-treated rats. Our investigation demonstrated that sub-acute exposure to SMF induced oxidative stress, which may be prevented by a pretreatment with selenium.

Effect of age‐dependent exposure to lead on hepatotoxicity and nephrotoxicity in male rats

Lead is known to induce a broad range of physiological, biochemical, and behavioral dysfunctions in laboratory animals and humans. This includes age-specific variations in absorption, retention, and tissue distribution of lead. This study was carried out to investigate the effects of chronic exposure to lead (50 mg/L) on liver and kidneys of two different age groups of male rats treated with lead from delivery until puberty period (40 days) and postpuberty period (65 days). For this purpose, the concentrations of thiobarbituric acid reactive substance (TBARS), total thiol groups (SH), and superoxide dismutase (SOD) activity were measured in the liver and kidney of rats. Renal function was analyzed by determining creatinine, acid uric, and urea. Plasma activities of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and albumin were determined spectrophotometrically to evaluate hepatic function. These markers of damage were determined to assess the level of toxicity in these animals. Our results clearly show that the administration of lead produces oxidative damage in liver and kidney, as strongly suggested by the significant increase in TBARS, decrease in total SH, and the alteration of SOD activity. In young lead-exposed animals, lead-induced perturbations on the synthetic function of the liver and the kidney were more pronounced. However, nephropathy is evident for adult lead-exposed animals. It is concluded that lead induces severe hepatic and renal toxicity, which depends on the age of the animals and the target organ.

Effect of dietary energy intake on erythrocytic antioxidant defence in growing lambs fed a wheat straw-based diet

Twenty-four Muzaffarnagari lambs (~8 months, 26.56 ± 2.04 kg), consisting 12 each of male and female, were used for ascertaining the effect of dietary energy restriction on the erythrocytic antioxidant defence including lipid peroxidation. The lambs, allotted randomly into three equal groups, were fed on wheat straw-based diets to provide 100, 80 and 70% of calculated metabolisable energy (ME) requirements. Bodyweight gain and feed intake were recorded. Blood samples were collected at the start and thereafter at 60-day intervals during 180 days of experimental duration and analysed for malonyl dialdehyde (MDA), reduced glutathione (GSH) and total thiol groups in addition to catalase, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione S-transferase. Dietary treatments imparted significant (P &lt; 0.001) effects on feed intake and average daily gain. The haemoglobin and haematocrit contents in blood reduced significantly (P &lt; 0.001) on reduction in dietary energy levels. The dietary alterations elicited no change in the activities of SOD, catalase and glutathione S-transferase, but reduced activities of GSH-Px (P &lt; 0.001) and GSH (P = 0.133) were evident on feeding the diet with 70% ME. Concentrations of total thiols decreased (P &lt; 0.001) with reduced energy level. Both the energy-restricted groups exhibited a significant (P &lt; 0.001) increase in MDA, indicative of increased lipid peroxidation. It was concluded that long-term energy malnutrition on a wheat straw-based diet reduces the erythrocytic antioxidant defence in growing lambs.

The involvement of oxidative stress in the mechanisms of damaging cadmium action in bone tissue: A study in a rat model of moderate and relatively high human exposure

It was investigated whether cadmium (Cd) may induce oxidative stress in the bone tissue in vivo and in this way contribute to skeleton damage. Total antioxidative status (TAS), antioxidative enzymes (glutathione peroxidase, superoxide dismutase, catalase), total oxidative status (TOS), hydrogen peroxide (H2O2), lipid peroxides (LPO), total thiol groups (TSH) and protein carbonyl groups (PC) as well as Cd in the bone tissue at the distal femoral epiphysis and femoral diaphysis of the male rats that received drinking water containing 0, 5, or 50mg Cd/l for 6months were measured. Cd, depending on the level of exposure and bone location, decreased the bone antioxidative capacity and enhanced its oxidative status resulting in oxidative stress and oxidative protein and/or lipid modification. The treatment with 5 and 50mg Cd/l decreased TAS and activities of antioxidative enzymes as well as increased TOS and concentrations of H2O2 and PC at the distal femur. Moreover, at the higher exposure, the concentration of LPO increased and that of TSH decreased. The Cd-induced changes in the oxidative/antioxidative balance of the femoral diaphysis, abundant in cortical bone, were less advanced than at the distal femur, where trabecular bone predominates. The results provide evidence that, even moderate, exposure to Cd induces oxidative stress and oxidative modifications in the bone tissue. Numerous correlations noted between the indices of oxidative/antioxidative bone status, and Cd accumulation in the bone tissue as well as indices of bone turnover and bone mineral status, recently reported by us (Toxicology 2007, 237, 89–103) in these rats, allow for the hypothesis that oxidative stress is involved in the mechanisms of damaging Cd action in the skeleton. The paper is the first report from an in vivo study indicating that Cd may affect bone tissue through disorders in its oxidative/antioxidative balance resulting in oxidative stress.

L-carnitine protects plasma components against oxidative alterations

Objective l-Carnitine as a dietary supplement has been reported to have a beneficial effect on several cardiovascular risk parameters and exercise capacity, but the biological relevance of its activity is poorly understood. Dietary supplements (including l-carnitine) are often used to foster exercise performance; however, these may affect some pathways of human body metabolism. The aim of this study in vitro was to determine antioxidative properties of l-carnitine (0.1–100 μM) added to plasma and to assess if l-carnitine might protect plasma proteins and lipids against oxidative/nitrative damage (determined by levels of protein carbonyl groups, thiols, 3-nitrotyrosine formation and thiobarbituric-acid reactive substances generation) caused by 100 μM peroxynitrite (ONOO −), a strong physiologic oxidative/nitrative agent. Methods The level of carbonyl group generation was measured by a colorimetric method. For the estimation of 3-nitrotyrosine formation, a competition enzyme-linked immunosorbent assay was performed. Plasma lipid peroxidation was measured spectrophotometrically as the production of thiobarbituric-acid reactive substances. High-performance liquid chromatography was used to analyze total free thiol groups of plasma proteins and low-molecular-weight thiols (glutathione, cysteine, and homocysteine) in plasma. Results The l-carnitine added to plasma inhibited in vitro ONOO −-induced oxidation and nitration of blood plasma proteins. Incubation of plasma with peroxynitrite resulted in the decrease of protein thiols. l-Carnitine had a protective effect on peroxynitrite-induced decreased −SH level in plasma proteins. The presence of l-carnitine also prevented the decrease of low-molecular-weight thiols (glutathione, cysteine, and homocysteine) in plasma caused by peroxynitrite and protected plasma lipids against peroxidation induced by peroxynitrite. Conclusions These results demonstrated that l-carnitine possesses antioxidative activity.

Studies on antioxidant effects of the red grapes seed extract fromVitis Vinifera, Burgund Mare, Recaşin pregnant rats

To estimate the effects of hydroethanolic red grapes seeds extract obtained from Vitis vinifera, Burgund Mare variety, Recaş , Romania (BMR) on oxidant-antioxidant ballance, as compared to ascorbic acid, during pregnancy in rats. Thirty Wistar female rats were assigned to three groups (n=10) which were administered by gavage: Group I, 3 x 100 mg/kg body weight saline, Group II - BMR 3 x 30 mg gallic acid equivalents/kg body weight; Group III - vitamin C 3 x 100 mg/kg body weight on days 1, 7 and 14 of pregnancy. On day 21 blood samples were collected. Malon dyaldehyde, lipid peroxides, protein carbonyls, nitric oxide (as oxidative stress parameters) and hydrogen donor ability and total thiol groups (as antioxidant parameters) serum concentrations were measured. Vitamin C significantly enhanced the antioxidant capacity of plasma (hydrogen donor ability, p=0.0001; thiol groups, p=0.0001), as well as nitric oxide levels (p=0.001). The extract increased the plasma antioxidant capacity (hydrogen donor ability, p=0.001; thiol groups p=0.001) and did not elevate the nitric oxide plasma levels in pregnant rats.In conclusion, in the chosen dose, the red grapes seed extract enhanced the plasma antioxidant capacity and did not influence the nitric oxide levels in pregnant rats.

Apolipoprotein, C-Reactive Protein and Oxidative Stress Parameters in Dyslipidemic Type 2 Diabetic Patients Treated or Not with Simvastatin

Oxidative stress is considered an important factor in the development of diabetic complications that causes a variety of changes such as oxidative modification of membrane lipids, nucleic acids and cellular proteins. Dyslipidemia is frequently associated with diabetes and cardiovascular disease. In this context, the objective of this study was to evaluate oxidative modifications of plasma proteins and lipids in non dyslipidemic type 2 diabetic (T2D) patients, in dyslipidemic T2D patients treated or not with simvastatin and in healthy subjects to investigate whether treatment with low doses of simvastatin plays a protective role on the lipid and protein oxidative damage in these patients. We determined oxidative damage of plasma proteins by carbonyl assay and total thiol group determination. We also characterized the membrane damage in terms of lipid peroxidation by measuring malonaldehyde (MDA) in nondyslipidemic T2D patients, dyslipidemic T2D patients treated with simvastatin (20 mg/day), dyslipidemic T2D patients not treated with simvastatin and in healthy age-matched control subjects. Our results showed that dyslipidemic T2D patients not treated with simvastatin had significantly higher plasma protein carbonyl groups and MDA when compared to dyslipidemic T2D patients treated with simvastatin and control group. Thiol concentrations from dyslipidemic T2D patients not treated with simvastatin were significantly lower than treated patients and controls. It was verified that the thiols groups were inversely correlated with apolipoprotein B and positively correlated with apolipoprotein A-I. These results demonstrated that treatment with low doses of simvastatin can minimize the protein and lipid oxidative damage in dyslipidemic T2D patients.

Ultraendurance exercise increases the production of reactive oxygen species in isolated mitochondria from human skeletal muscle

Exercise-induced oxidative stress is important for the muscular adaptation to training but may also cause muscle damage. We hypothesized that prolonged exercise would increase mitochondrial production of reactive oxygen species (ROS) measured in vitro and that this correlates with oxidative damage. Eight male athletes (24-32 yr) performed ultraendurance exercise (kayaking/running/cycling) with an average work intensity of 55% V(O(2peak)) for 24 h. Muscle biopsies were taken from vastus lateralis before exercise, immediately after exercise, and after 28 h of recovery. The production of H(2)O(2) was measured fluorometrically in isolated mitochondria with the Amplex red and peroxidase system. Succinate-supported mitochondrial H(2)O(2) production was significantly increased after exercise (73% higher, P = 0.025) but restored to the initial level at recovery. Plasma level of free fatty acids (FFA) increased fourfold and exceeded 1.2 mmol/l during the last 6 h of exercise. Plasma FFA at the end of exercise was significantly correlated to mitochondrial ROS production (r = 0.74, P < 0.05). Mitochondrial content of 4-hydroxy-nonenal-adducts (a marker of oxidative damage) was increased only after recovery and was not correlated with mitochondrial ROS production. Total thiol group level and glutathione peroxidase activity were elevated after recovery. In conclusion, ultraendurance exercise increases ROS production in isolated mitochondria, but this is reversed after 28 h recovery. Mitochondrial ROS production was not correlated with oxidative damage of mitochondrial proteins, which was increased at recovery but not immediately after exercise.