Erythrocyte Membrane Lipid Peroxidation Research Articles

Lipid peroxidation associated with anemia in rats experimentally infected with Trypanosoma evansi

This study aimed to assess the plasma lipid peroxidation and the susceptibility of erythrocytes to in vitro peroxidation as indicators of oxidative damage in erythrocytes and their roles in the pathogenesis of anemia during the early acute phase of Trypanosoma evansi infection in rats. Fifty male Wistar rats were randomly distributed into seven groups: three trypanosome-infected groups (T 2, T 4 and T 6; n = 10 animals per group) and four uninfected controls (C 0, C 2, C 4 and C 6; n = 5 animals per group). Animals from trypanosome-infected groups were inoculated intraperitoneally with 10 6 trypanosomes. Blood samples were collected by cardiac puncture before infection (day 0; group C 0) or on the 2nd (C 2 and T 2), 4th (C 4 and T 4) and 6th (C 6 and T 6) day post-infection (dpi). Samples were analyzed for red blood cell (RBC) count, hemoglobin (Hb) concentration, packed cell volume (PCV), plasma malondialdehyde (MDA) and in vitro peroxidation of erythrocytes. The mean values of the hematological indices gradually decreased in the infected rats compared with the control. MDA was significantly increased ( P < 0.001) on the 6th dpi in infected versus control animals and was negatively correlated with PCV ( P < 0.001; R 2 = 0.372). The values for erythrocyte in vitro peroxidation were higher for groups T 4 and T 6 than for the control rats ( P < 0.01). A positive correlation between erythrocyte peroxidation and MDA ( P < 0.001; R 2 = 0.414) was observed. The results of this study indicate that T. evansi infection in rats is associated with oxidative stress, indicated by lipid peroxidation and oxidative damage in erythrocyte membranes, as demonstrated by in vitro peroxidation. This may be one of the causes of anemia in acute trypanosomosis.

Modulatory role of Emblica officinalis against alcohol induced biochemical and biophysical changes in rat erythrocyte membranes

This study investigated the protective effect of Emblica officinalis against alcohol-induced biochemical and biophysical changes in rat erythrocyte membranes. Thirty-two male rats were divided into four groups ( n = 8 in each group): control (C), alcohol (A), alcohol plus Emblica fruit extract (A + EFE) and Emblica fruit extract (EFE) alone. Administration of twenty percent alcohol (5 g/kg body weight) to rats significantly increased cholesterol/phospholipid (C/P) ratio, lipid peroxidation and the activities of Na +/K + and Mg 2+ ATPases in erythrocyte membranes as well as augmented nitric oxide (NO) levels. However, membrane fluidity studies using the fluorescent probe DPH (1,6 diphenyl 1,3 hexatriene) reveals that alcohol administration significantly ( p < 0.05) increased membrane anisotropic values and altered membrane individual phospholipid content. Administration of EFE (250 mg/kg body weight) to alcoholic rats resulted in significant ( p < 0.05) reduction of NO levels, erythrocyte membrane lipid peroxidation, C/P ratio, activities of Na +/K + and Mg 2+ ATPases and fluorescent anisotropic values. Further, EFE administration to alcoholic rats beneficially modulated membrane properties as evidenced from the contents of total phospholipids as well individual phospholipid classes. The tannoid principles present in Emblica offers protection against alcohol induced adverse effects in rats.

Bidis — hand-rolled, Indian cigarettes: Induced biochemical changes in plasma and red cell membranes of human male volunteers

Objective To investigate the effect of bidi smoking on erythrocyte antioxidant status, membrane fluidity. Design and methods Thirty experimental and control subjects (mean age 35 ± 5) were selected for the study. Experimental subjects smoke 22 ± 4 bidis per day for 8–10 years. Results Increase in plasma total cholesterol, LDL-cholesterol, triglycerides, lipid peroxidation, protein carbonyls with a decrease in HDL-cholesterol, thiol groups as well as increased erythrocyte catalase (CAT), superoxide dismutase (SOD), decreased glutathione peroxidase (GPx) activity and reduced glutathione (GSH) content was observed in bidi smokers. Increase in the erythrocyte membrane lipid peroxidation, cholesterol phospholipids (C/P) ratio as well as decrease in protein and Na +/K +-ATPase activity was observed. Increase in nitrite/nitrate (NOx) levels of plasma, red cell lysate was positively correlated with C/P ratio ( r = 0.614) and Na +/K +-ATPase ( r = 0.435) in bidi smokers. Conclusions Bidi smoke alters antioxidant status, red cell membrane fluidity and increases atherogenicity.

Effect of Copper-Hydroquinone Complex on Oxidative Stress-Related Parameters in Human Erythrocytes (In Vitro)

The effect of in vitro exposure of human erythrocytes to micromolar concentrations of hydroquinone and copper simultaneously on oxidative status-related biochemical parameters was studied. Hydroquinone is a component of cigarette smoke and serum copper level is increased in smokers. Copper forms a complex with hydroquinone and enhances its auto-oxidation to benzoquinone which covalently binds to sulfhydryl group containing compounds like reduced glutathione. In this study, copper increased H2O2 production by hydroquinone. Hydroquinone either alone or in the presence of copper produced a decrease of reduced glutathione level without altering methemoglobin concentration and erythrocyte lipid peroxidation. Catalase inhibition by sodium azide depleted reduced glutathione level further. Copper–hydroquinone complex mediated glutathione depletion in the catalase containing RBC was not decreased by antioxidant, butylated hydroxytoluene. From the known facts and above findings, it is suggested that depletion of reduced glutathione by hydroquinone in the presence of copper in catalase active RBC may be due to the formation of 1, 4 benzoquinone adduct of reduced glutathione and to some extent due to binding of copper to the thiol group of reduced glutathione rather than conversion to oxidized glutathione via reactive oxygen species. Depletion of reduced glutathione by N-ethylmaleimide pretreatment followed by copper-hydroquinone treatment had no effect on methemoglobin level or lipid peroxidation. Furthermore, copper-hydroquinone complex did not increase erythrocyte susceptibility to oxidative stress. This suggests hydroquinone in the presence of copper does not contribute to erythrocyte membrane lipid peroxidation seen in smokers. Criteria for ideal antioxidant supplementation in smokers were suggested.

Effect of 2-hydroxy-4-methoxy benzoic acid from the roots ofHemidesmus indicuson streptozotocin-induced diabetic rats

The aim of the present study was to investigate the effect of 2-hydroxy-4-methoxy benzoic acid isolated from the roots of Hemidesmus indicus on plasma glucose, plasma, erythrocyte and erythrocyte membrane lipid peroxidation and membrane-bound Ca2+ ATPase activity in streptozotocin-induced diabetic rats. In our study, diabetic rats had increased levels of blood glucose and lipid peroxidation in plasma, erythrocytes and erythrocyte membrane and decreased level of plasma insulin and decreased activity of low affinity Ca2+ ATPase in erythrocytes. Restoration of plasma insulin and glucose in diabetic rats indicates the effect of HMBA on insulin, glucose and lipid peroxidation. HMBA also restored diabetes-induced alterations in the activity of membrane-bound Ca2+ ATPase. Based on the results of this study it can be concluded that HMBA mediated normalization of membrane-bound ATPase in erythrocytes is due to improved glycemic control and antioxidant activity.

Anti-inflammatory and hypolipemic effects in vitro of simvastatin comparing to epicatechin in patients with type-2 hypercholesterolemia

Objective The study involved 25 patients with type-2 hypercholesterolemia (mean age 49.3 ± 11.3). The control group consisted of 28 healthy individuals (mean age 50.7 ± 7.2). Methods The cholesterol concentrations in plasma membranes of erythrocytes were measured by means of Liebermann-Burchard reagent. The membrane lipid peroxidation in whole erythrocytes was determined. The membrane fluidity was estimated by spin labelled method. Results The in vitro study shows that the cholesterol concentration in membranes incubated with simvastatin and epicatechin decreases; in healthy donors there are no changes. Simvastatin does not lead to changes in the lipid peroxidation in the in vitro data. Epicatechin decreases the level of membrane lipid peroxidation in patients with hypercholesterolemia and in healthy donors. Simvastatin and epicatechin cause an increase in the fluidity of plasma membranes of erythrocytes. Conclusions Simvastatin causes the decrease in cholesterol concentration in erythrocytes membranes not only in the in vivo but also the in vitro experiments. Flavonoids have antioxidant properties in vitro. Simvastatin influences the lipid peroxidation only in vivo, not in vitro systems. This observation is an additional contribution to the statins’ pleiotropic effect.

Potential cytoprotection: antioxidant defence by caffeic acid phenethyl ester against free radical-induced damage of lipids, DNA, and proteins

Oxidative stress is considered to be a major cause of cellular injuries in a variety of chronic health problems, such as carcinogenesis and neurodegenerative disorders. Caffeic acid phenethyl ester (CAPE), derived from the propolis of honeybee hives, possesses a variety of biological and pharmacological properties including antioxidant and anticancer activity. In the present study, we focused on the diverse antioxidative functionalities of CAPE and its related polyphenolic acid esters on cellular macromolecules in vitro. The effects on human erythrocyte membrane ghost lipid peroxidation, plasmid pBR322 DNA, and protein damage initiated by the water-soluble initiator 2,2'-azobis(2-amidinopropane) hydrochloride (AAPH) and hydrogen peroxide (H(2)O(2)) were monitored by formation of hydroperoxides and by DNA nicking assay, single-cell alkaline electrophoresis, and SDS-polyacrylamide gel electrophoresis. Our results showed that CAPE and its related polyphenolic acid esters elicited remarkable inhibitory effects on erythrocyte membrane lipid peroxidation, cellular DNA strand breakage, and protein fragmentation. The results suggest that CAPE is a potent exogenous cytoprotective and antigenotoxic agent against cell oxidative damage that could be used as a template for designing novel drugs to combat diseases induced by oxidative stress components, such as various types of cancer.

Detection of Membrane Fluidity in Submitochondrial Particles of Platelets and Erythrocyte Membranes from Mexican Patients with Alzheimer Disease by Intramolecular Excimer Formation of 1,3 Dipyrenylpropane

It has been suggested that mitochondrial dysfunction and defects in membrane structure could be implied in AD pathogenesis. The aim of the present work was the study of membrane fluidity in submitochondrial platelet particles and erythrocyte membranes from Mexican patients. Blood samples were obtained from 30 patients with Alzheimer disease and 30 aged-matched control subjects. Membrane fluidity determinations were done using a very low concentration of the fluorescent dipyrenylpropane probe incorporated in both types of membranes. This probe is able to give excimer and monomer fluorescence, therefore it can be used to monitor fluidity changes in biological membranes. The data obtained showed that in submitochondrial particles from AD patients, the excimer to monomer fluorescent intensity ratio was lower (0.231 ± 0.008) than aged-matched control subjects (0.363 ± 0.014). Therefore, membrane fluidity was lower in AD samples. On the other hand, we found similar membrane fluidity in erythrocytes from AD patients and aged-matched controls: the fluorescent intensity ratios were 0.312 ± 0.03 and 0.305 ± 0.033, respectively. In addition, lipid peroxidation in submitochondrial particles and erythrocyte membranes was higher in AD samples than in aged-matched controls. These data suggest that submitochondrial platelet particles are more sensitive to oxidative stress than erythrocyte membranes.

Effect of sulphated polysaccharides on erythrocyte changes due to oxidative and nitrosative stress in experimental hyperoxaluria.

Kidney stones are known to haunt humanity for centuries and increase in oxalate is a predominant risk factor for stone formation. The present study was initiated with a notion to study the oxidative and nitrosative stress on erythrocytes under oxalate stress and the putative role of sulphated polysaccharides. Hyperoxaluria was induced in two groups by the administration of 0.75% ethylene glycol in drinking water for 28 days and one of them was treated with sulphated polysaccharides from Fucus vesiculosus from the 8th day to the end of the experimental period of 28 days at a dose of 5 mg/kg body weight subcutaneously. Control and drug control (sulphated polysaccharides alone) were also included in the study. Glycolic and glyoxylic acid levels of urine were analyzed as an index of hyperoxaluria. The plasma enzymic markers of cellular integrity, redox status of red blood cells, osmotic fragility, and (14)C-oxalate binding were investigated. Urine and plasma nitric oxide metabolites, expression of inducible nitric oxide synthase protein, and mRNA were assessed in kidney to evaluate the nitrosative stress. Increased levels of glycolic and glyoxylic acid in urine indicated the prevalence of hyperoxaluria in ethylene glycol-administered groups. Plasma aspartate and alanine transaminase were not altered, but alkaline phosphatase and lactate dehydrogenase of hyperoxaluric group were increased indicating tissue damage. Activities of antioxidant enzymes were decreased, whereas erythrocyte membrane lipid peroxidation was increased in hyperoxaluric rats. Moreover, an altered fragility with an increase in oxalate binding activity was observed in hyperoxaluric group. Increase in nitric oxide metabolites levels in urine and plasma along with an increase in expression of inducible nitric oxide synthase protein and mRNA in kidney were observed in hyperoxaluric rats. Administration of sulphated polysaccharides to hyperoxaluric rats averted the abnormal increase in urinary glycolic and glyoxylic acid levels and enzyme activities, decreased lipid peroxidation, and increased the activities of antioxidant enzymes. Furthermore, increased nitrosative stress accompanying hyperoxaluria was also normalized on sulphated polysaccharides treatment. To conclude, sulphated polysaccharide administration was able to maintain the integrity of erythrocyte membrane and decrease the damage to erythrocytes in hyperoxaluria.

The Effect of Simvastatin on Erythrocyte Membrane Fluidity During Oxidative Stress Induced by Cardiopulmonary Bypass: A Randomized Controlled Study

Background: Abnormal erythrocyte deformability can cause severe complications during cardiopulmonary bypass (CPB) surgery, including both hemolysis and perfusion abnormalities. Objectives: The goals of this study were to evaluate changes in erythrocyte membrane fluidity and lipid peroxidation during CPB and to examine the effect of simvastatin treatment on these parameters. Methods: Patients undergoing cardiac surgery involving CPB were selected and randomized to receive either simvastatin 40 mg/d or placebo for 3 weeks before surgery. Three blood samples were obtained at different times during surgery for analysis of erythrocyte membrane fluidity, anion permeability, and lipid peroxidation. Erythrocyte ghosts were prepared and incubated with a lipophilic fluorescent probe (diphenyl-hexatriene), and fluorescence anisotropy was evaluated by spectrophotofluorimetric assay as a measure of membrane fluidity. Anion permeability was evaluated by the specific absorption of methemoglobin (C M) at 590 and 635 nm after treatment of heparinized blood with NaNO2. The formation of thiobarbituric acid-reactive substances was evaluated as an index of lipid peroxidation. Aspartate transaminase and lactate dehydrogenase were also measured as indices of hemolysis. Results: Forty patients met the inclusion criteria (20 simvastatin, 20 placebo). Their characteristics differed significantly at baseline only in terms of the lipid profile; the statin group had higher levels of high-density lipoprotein cholesterol ( P = 0.01) and lower levels of low-density lipoprotein cholesterol ( P = 0.001) than the placebo group. CPB was found to significantly modify characteristics of the erythrocyte membrane. Compared with preoperative values, CPB induced decreases in both mean (SD) erythrocyte membrane fluidity and anion permeability (preoperative C M: 0.69 [0.02]; 24-hour postoperative C M: 0.18 [0.02]; P < 0.001) and an increase in mean (SD) membrane lipid peroxidation (preoperative malonyl dialdehyde [MDA]: 0.21 [0.01] nmol/mL; postoperative MDA: 0.10 [0.02] nmol/mL; P < 0.001). Treatment with simvastatin was associated with a significant reduction in mean (SD) membrane lipid peroxidation both preoperatively and at 24 hours postoperatively compared with placebo (preoperative MDA: 0.07 [0.01] vs 0.10 [0.02] nmol/mL, respectively; P < 0.05; postoperative MDA: 0.10 [0.04] vs 0.21 [0.01] nmol/mL; P < 0.05). In addition, statin treatment was associated with significant increases in anion permeability preoperatively and postoperatively compared with placebo (preoperative C M: 0.79 [0.01] vs 0.69 [0.02]; P < 0.01; 24-hour postoperative C M: 0.30 [0.01] vs 0.18 [0.02]; P < 0.01). Conclusion: The results of this study suggest that among these patients undergoing CPB surgery, use of simvastatin for 3 weeks before the surgery had significant beneficial effects on erythrocyte membrane fluidity, lipid peroxidation, and anion permeability.

Photo-induced lipid peroxidation of erythrocyte membranes by a bis-methanophosphonate fullerene

Using human erythrocyte membranes (EMs) as a model system, we have examined photo-induced lipid peroxidation by a bis-methanophosphonate fullerene (BMPF) and four other fullerene derivatives including a mono-methanophosphonic acid fullerene (MMPF), a dimalonic acid C 60 (DMA C 60), a trimalonic acid C 60 (TMA C 60) and a polyhydroxylated fullerene (fullerol). Lipid peroxidation was assessed as the malondialdehyde (MDA) level measured by the thiobarbituric acid assay. It was observed that BMPF increased the MDA level of EMs after irradiation in both time- and dose-dependent manners. The photo-induced activity became very significant ( p < 0.01) under the conditions of either the concentration of 10 μM and irradiation time of 30 min or the concentration of 5 μM and irradiation time of 60 min. Involvement of reactive oxygen species (ROS) in the activity was also examined by specific inhibitors of singlet oxygen, superoxide anions and hydroxyl radicals, respectively. While all three kinds were found responsible for the activity, the former two might play more important roles than the last one. Furthermore, the activity of BMPF was the strongest among all tested fullerene derivatives. These results indicated BMPF was a potential photosensitizer that would find application in photodynamic therapy.

Ameliorative Influence of Sesame Lignans on Lipid Profile and Lipid Peroxidation in Induced Diabetic Rats

Sesame lignans are working as antioxidants in various physiological functions. In the present study, the antioxidative effect of sesame lignans is examined in chemically induced diabetes mellitus (DM) in rats against lipid profile and lipid peroxidations. DM was induced in four groups of rats by injection of alloxan. The control groups (non-diabetic and diabetic) received a diet containing sunflower oil while the rest of the three experimental diabetic groups received a diet containing 0.25% alpha-tocopherol (D-Toc), 0.5% sesame lignan (D-SL), and 0.25% alpha-tocopherol+0.25% sesame lignan (D-Toc-SL) in sunflower oil for 4 weeks. Lipid profile and lipid peroxidations of plasma, erythrocyte membrane (EM), and liver tissues were measured. The total cholesterol, non-HDL cholesterol, plasma lipid peroxidation, and also LDL-peroxidation decreased, and HDL cholesterol increased significantly (P<0.05) in all the experimental groups as compared to the control diabetic sunflower oil group. The triacylglycerol (TAG) level in plasma decreased significantly in the D-SL and D-Toc-SL groups as compared to control diabetic group. Significant decrease in TAG level was observed in the D-SL group as compared to the D-Toc group. LDL peroxidation also decreased significantly in the D-Toc-SL group as compared to the D-Toc group. EM lipid peroxidation and liver lipid peroxidation decreased significantly in the D-Toc, D-SL, and D-Toc-SL groups as compared to the control diabetic group. Liver TAG level decreased more significantly in the D-SL and D-Toc-SL groups than in the control diabetic group. So, sesame lignans at 0.5% level and sesame lignan + alpha-tocopherol significantly ameliorate the alteration in lipid profile and the adverse free radical generative influence of DM induced by alloxan.

Antioxidant Actions of Phenolic Compounds Found in Dietary Plants on Low-Density Lipoprotein and Erythrocytes in Vitro

Objective: There is increasing interest in the study of the antioxidant actions of plant phenolic compounds as evidence shows that consumption of plant products rich in these compounds contributes to protection from a number of ailments including cardiovascular diseases. In the present study, the antioxidant effects of selected phenolic compounds from dietary sources, namely barbaloin, 6-gingerol and rhapontin, were investigated.Methods: Low-density lipoprotein (LDL), erythrocytes and erythrocyte membranes were subjected to several in vitro oxidative systems. The antioxidant effects of the phenolic compounds were assessed by their abilities in inhibiting hemolysis and lipid peroxidation of LDL and erythrocyte membranes, and in protecting ATPase activities and protein sulfhydryl groups of erythrocyte membranes.Results: 6-Gingerol and rhapontin were found to exhibit strong inhibition against lipid peroxidation in LDL induced by 2,2′-azobis(2-amidinopropane) hydrochloride (AAPH) and hemin while barbaloin possessed weaker effects. A similar order of antioxidant potencies among the three compounds was observed on the lipid peroxidation of erythrocyte membranes in a tert-butylhydroperoxide (tBHP)/hemin oxidation system. On the other hand, barbaloin and rhapontin were comparatively stronger antioxidants than 6-gingerol in preventing AAPH-induced hemolysis of erythrocytes. Among the three compounds, only barbaloin protected Ca2+-ATPase and protein sulfhydryl groups on erythrocyte membranes against oxidative attack by tBHP/hemin. Interestingly, rhapontin demonstrated protective actions on Na+/K+-ATPase in a sulfhydryl group-independent manner under the same experimental conditions.Conclusions: In view of their protective effects on LDL and erythrocytes against oxidative damage, these phenolic compounds might have potential applications in prooxidant state-related cardiovascular disorders.

Antioxidant effect of diphenyl diselenide against sodium nitroprusside (SNP) induced lipid peroxidation in human platelets and erythrocyte membranes: An in vitro evaluation

An in vitro evaluation on the antioxidant effect of diphenyl diselenide (PhSe)(2), an organochalcogenide, against sodium nitroprusside (SNP)-induced lipid peroxidation (LPO) was conduced. Human platelets and erythrocyte membranes (ghosts), as well as rat brain homogenates (S(1)), were pre-incubated with different concentrations of SNP (0-10 microM). All SNP concentrations tested significantly increased LPO in human platelets and S(1). Platelets were more sensitive to SNP-induced peroxidative damage when compared to S(1). SNP 10 microM decreased glutathione peroxidase (GPx) activity and did not affect glutathione reductase (GR) and catalase (CAT) activities in human platelets. However, ghosts were insensitive to SNP-induced LPO and no changes on GPx, GR and CAT activities were observed. Diphenyl diselenide significantly protected human platelets against SNP-induced LPO and recovered GPx inactivation. This effect was more evident at (PhSe)(2) concentrations above 2 microM. The presented results indicate that (PhSe)(2) exerts protective effects on SNP-induced oxidative damage in human blood components and in rat brain. These phenomena seem to be related to its thiol peroxidase-like activity and to a possible direct interaction with SNP and derivatives. Based on our results and on literature, diphenyl diselenide can be pointed as a promising antioxidant molecule.

Oxygen-related processes in red blood cells exposed to tert-butyl hydroperoxide

The correlation between the oxidative processes in tert-butyl hydroperoxide (tBHP)-exposed red blood cells and the reactions of oxygen consumption and release were investigated. Red blood cell exposure to tBHP resulted in transient oxygen release followed by oxygen consumption. The oxygen release in red blood cells was associated with intracellular oxyhaemoglobin oxidation. The oxygen consumption proceeded in parallel with free radical generation, as registered by chemiluminescence, but not to membrane lipid peroxidation. The oxygen consumption was also observed in membrane-free haemolyzates. The order of the organic hydroperoxide-induced reaction of oxygen release with respect to the oxidant (tBHP) was estimated to be 0.9 ± 0.1 and that of the oxygen consumption reaction was determined to be 2.4 ± 0.2. The apparent activation energy values of the oxygen release and oxygen consumption were found to be 107.5 ± 18.5 kJ/mol and 71.0 ± 12.5 kJ/mol, respectively. The apparent pKa value for the functional group(s) regulating the cellular oxyHb interaction with the oxidant in tBHP-treated red blood cells was estimated to be 6.7 ± 0.2 and corresponded to that of distal histidine protonation in haemoprotein. A strong dependence of tBHP-induced lipid peroxidation on the oxygen concentration in a red blood cell suspension was observed (P50 = 32 ± 3 mmHg). This dependence correlated with the oxygen dissociation curve of cellular haemoglobin. The order of the membrane lipid peroxidation reaction with respect to oxygen was found to be 0.5 ± 0.1. We can conclude that the intensity of the biochemical process of membrane lipid peroxidation in tBHP-exposed erythrocytes is controlled by small changes in such physiological parameters as the oxygen pressure and oxygen affinity of cellular haemoglobin. Neither GSH nor oxyhaemoglobin oxidation depended on oxygen pressure.

Could cholesterol bound to haemoglobin be a missing link for the occasional inverse relationship between superoxide dismutase and glutathione peroxidase activities?

The concept of an anti-oxidant defence system as a means to prevent oxidative cell damage implies balanced activities of anti-oxidant defence enzymes. As well as positive correlations between anti-oxidant enzyme activities in human erythrocytes, it has been observed that sometimes when glutathione peroxidase activity is increased, CuZn-superoxide dismutase activity is decreased. In our current study we have examined the plasma lipid profile and the anti-oxidant defence enzymes in erythrocytes from humans, pigs, and bulls. We found that a negative correlation existed between CuZn-superoxide dismutase and glutathione peroxidase activities in human erythrocytes when the concentrations of both plasma triglycerides and total cholesterol were high. This correlation was also found in pig erythrocytes, but not in bull erythrocytes. We propose that cholesterol could affect membrane lipid peroxidation and superoxide generation in erythrocytes via the recently found fraction of cholesterol bound to haemoglobin, termed haemoglobin-cholesterol.

Melatonin directly scavenges free radicals generated in red blood cells and a cell-free system: Chemiluminescence measurements and theoretical calculations

Melatonin, a pineal secretory product, has properties of both direct and indirect powerful antioxidant. The aim of the present study was to compare the radical-scavenging, structural and electronic properties of melatonin and tryptophan, precursor of melatonin. Using the alkoxyl- and peroxyl radical-generating systems [the organic peroxide-treated human erythrocytes and a cell-free system containing the azo-initiator 2,2′-azobis(2-amidinopropane)dihydrochloride], we evaluated the radical-scavenging effects of melatonin and tryptophan. Melatonin rather than tryptophan at concentrations of 100–2000 μM markedly inhibited membrane lipid peroxidation in human erythrocytes treated with organic hydroperoxide as well as radical-induced generation of luminol-dependent chemiluminescence. The apparent Stern–Volmer constants for inhibition of membrane lipid peroxidation by melatonin and tryptophan were estimated to be (0.23 ± 0.05) × 10 4 M − 1 and (0.02 ± 0.005) × 10 4 M − 1 , respectively. The apparent Stern–Volmer constants for inhibition of azo-initiator-derived peroxyl radical generation by melatonin and tryptophan were determined to be (0.42 ± 0.05) × 10 4 M − 1 and (0.04 ± 0.01) × 10 4 M − 1 , respectively. The structural and electronic properties of melatonin and its precursor, tryptophan, were determined theoretically by performing semi-empirical and ab initio calculations. The high radical-scavenging properties of melatonin may be explained by the high surface area value and high dipole moment value. From the thermodynamic standpoint, based on our calculations, N 1-acetyl- N 2-formyl-5-methoxykynuramine (AFMK), was the most stable end oxidative product of melatonin.

Screening of free radical scavenging capacity and antioxidant activities of Rosmarinus officinalis extracts with focus on location and harvesting times

Methanolic extracts from the leaves of Rosmarinus officinalis (rosemary) harvested from different locations of Turkey at four different times of the year were analyzed by HPLC, and their radical scavenging capacities and antioxidant activities were studied by various assays. The amounts of carnosol, carnosic acid and rosmarinic acid, active constituents of rosemary, varied in different geographical regions of growth, and also showed a seasonal variation. The levels of the constituents were higher in the warm months of June 2004 and September 2004. The antioxidant activities of 12 extracts were determined by in vitro DPPH radical scavenging activity, by Trolox equivalent antioxidant capacity (TEAC), and by reversing H2O2-induced erythrocyte membrane lipid peroxidation (EMLP). The two antioxidant enzyme activities of human erythrocyte, namely superoxide dismutase (SOD) and catalase (CAT), after in vitro incubation with the extracts, were also examined in order to see whether the observed effects are related to altered enzymatic efficiency. The resulting values were correlated with active metabolite and total phenol contents of the extracts. The results indicated that the plants harvested in September possessing higher levels of active constituent had superior antioxidant capacities compared to the ones collected at other times. With respect to the location, plants harvested from the Izmir region had lower total phenol and active constituent levels resulting in poorer antioxidant activity.

酸化的ストレスを軽減するｎ‐３脂肪酸摂取

Effects of supplementation of n-3 and n-6 fatty acids on lipid peroxidation and DNA damage of rat tissues are shown. Rats were fed diet containing 5% safflower oil (S) rich in n-6 fatty acids or fish oil (F) rich in n-3 fatty acids for 6 weeks. Lipid peroxidation of erythrocyte membranes and other tissues as assessed by thiobarbituric acid-reactive substances and phospholipid hydroperoxides of both diet groups were not significantly different, whereas lipid peroidation of erythrocyte membranes of F diet group was higher than that of S diet group when they were oxidized under atmospheric conditions. Lipid peroxidaton and vitamin E content of hepatocyteas after intreperitoneal injection of Fe (III) of F diet group were higher and lower, respectively, than those of S diet group, whereas DNA damage of the cells of F diet group was lower than those of S diet group as assessed by 8-hydroxydeoxyguanine and comet assay. In vitro supercoiled DNA damage induced by various oxidants was inhibited by unoxidized polyunsaturated linoleic acid and low density lipoprotein, supporting that polyunsaturated fatty acids suppressed oxidative damage of DNA. The results indicate that supplementation of n-3 fatty acids reduces oxidative damage of DNA as compared with that of n-6 fatty acids.

Dietary comparison of conjugated linolenic acid (9 cis, 11 trans, 13 trans) and α‐tocopherol effects on blood lipids and lipid peroxidation in alloxan‐induced diabetes mellitus in rats

The present study investigated the dietary effect of conjugated linolenic acid (CLnA) on lipid profiles and lipid peroxidations in alloxan-induced diabetes mellitus in rats. Diabetic rats were fed with 20% sunflower oil (diabetic control), sunflower oil supplemented with 0.5% CLnA, sunflower oil supplemented with 0.15% alpha-tocopherol, and sunflower oil containing 0.25% CLnA + 0.15% alpha-tocopherol. The results demonstrated that 0.5% CLnA, 0.15% alpha-tocopherol, and 0.25% CLnA + 0.15% alpha-tocopherol each on supplementation significantly lowered total cholesterol and non-HDL-cholesterol in comparison with the diabetic control group. The TAG level was significantly lowered in both the 0.15% alpha-tocopherol and 0.25% CLnA + 0.15% alpha-tocopherol groups. LDL-lipid peroxidation and erythrocyte membrane lipid peroxidation were reduced significantly in each of the experimental groups vs. the control group. The CLnA + alpha-tocopherol diet induced a greater reduction in membrane lipid and liver lipid peroxidation than the alpha-tocopherol diet alone. In conclusion, dietary CLnA exerts antioxidant activity as evidenced by reduced lipid peroxidation in chemically induced diabetes mellitus.