Peroxidative Damage To Membrane Lipids Research Articles

Erythroid spectrin binding modulates peroxidase and catalase activity of heme proteins.

Hemoglobin oxidation due to oxidative stress and disease conditions leads to the generation of ROS (reactive oxygen species) and membrane attachment of hemoglobin in-vivo, where its redox activity leads to peroxidative damage of membrane lipids and proteins. Spectrin, the major component of the red blood cell (RBC) membrane skeleton, is known to interact with hemoglobin and, here this interaction is shown to increase hemoglobin peroxidase activity in the presence of reducing substrate ABTS (2', 2'-Azino-Bis-3-Ethylbenzothiazoline-6-Sulfonic Acid). It is also shown that in the absence of reducing substrate, spectrin forms covalently cross-linked aggregates with hemoglobin which display no peroxidase activity. This may have implications in the clearance of ROS and limiting peroxidative damage. Spectrin is found to modulate the peroxidase activity of different hemoglobin variants like A, E, and S, and of isolated globin chains from each of these variants. This may be of importance in disease states like sickle cell disease and HbE-β-thalassemia, where increased oxidative damage and free globin subunits are present due to the defects inherent in the hemoglobin variants associated with these diseases. This hypothesis is corroborated by lipid peroxidation experiments. The modulatory role of spectrin is shown to extend to other heme proteins, namely catalase and cytochrome-c. Experiments with free heme and Raman spectroscopy of heme proteins in the presence of spectrin show that structural alterations occur in the heme moiety of the heme proteins on spectrin binding, which may be the structural basis of increased enzyme activity.

Therapeutic lithium alters polar head-group region of lipid bilayer and prevents lipid peroxidation in forebrain cortex of sleep-deprived rats

Lithium is regarded as a unique therapeutic agent for the management of bipolar disorder (BD). In efforts to explain the favourable effects of lithium in BD, a wide range of mechanisms was suggested. Among those, the effect of clinically relevant concentrations of lithium on the plasma membrane was extensively studied. However, the biophysical properties of brain membranes isolated from experimental animals exposed to acute, short-term and chronic lithium have not been performed to-date. In this study, we compared the biophysical parameters and level of lipid peroxidation in membranes isolated from forebrain cortex (FBC) of therapeutic lithium-treated and/or sleep-deprived rats. Lithium interaction with FBC membranes was characterized by appropriate fluorescent probes. DPH (1,6-diphenyl-1,3,5-hexatriene) and TMA-DPH (1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene p-toluenesulphonate) were used for characterization of the hydrophobic lipid core and Laurdan (6-dodecanoyl-2-dimethylaminonaphthalene) for the membrane-water interface. Lipid peroxidation was determined by immunoblot analysis of 4-HNE-(4-hydroxynonenal)-protein adducts. The organization of polar head-group region of FBC membranes, measured by Laurdan generalized polarization, was substantially altered by sleep deprivation and augmented by lithium treatment. Hydrophobic membrane interior characterized by steady-state anisotropy of DPH and TMA-DPH fluorescence was unchanged. Chronic lithium had a protective effect against peroxidative damage of membrane lipids in FBC. In summary, lithium administration at a therapeutic level and/or sleep deprivation as an animal model of mania resulted in changes in rat FBC membrane properties.

Prophylactic Administration of Nanocurcumin Abates the Incidence of Liver Toxicity Induced by an Overdose of Copper Sulfate: Role of CYP4502E1, NF-κB and Bax Expressions.

Background:The consequences of excess copper in human tissue are the alterations in the oxidative stress markers and peroxidative damage of membrane lipids. Unselective copper binding may be the clue to damaging impact to protein construction and hence modifying their biological functions. The aim of this study is to match the hepatoprotective efficacy of curcumin (CM) or nanocurcumin (NCM) with that of desferrioxamine (DSF; standard heavy metal chelator) against toxic doses of copper sulphate (CuSO4).Method:All treatments were given simultaneously with CuSO4 for 7 days.Result:CuSO4 administration elevated serum alanine transaminase, and hepatic nitric oxide (NO), lipid peroxide, and caspase-3 as well as protein expression of cytochrome P4502E1, and nuclear factor-κB (NF-κB) and Bax gene expressions. On the other hand, hepatic levels of reduced glutathione, superoxide dismutase, and interleukin-10 were decreased, whereas DNA degradation was increased as well compared with the control group. The administration of the aforementioned antioxidants ameliorated all the previous altered measured parameters. Interestingly, NCM achieved the most pronounced hepatoprotective effect nearly equivalent to that of DSF.Conclusion:It was concluded that NCM is considered a promising candidate against CuSO4 toxicity, and cytochrome P450, NF-κB, and Bax are involved in its toxicity and treatment.

Thylakoid membrane stability to heat stress studied by flash spectroscopic measurements of the electrochromic shift in intact potato leaves: influence of the xanthophyll content

ABSTRACTA flash‐induced transthylakoid electric field was measured at 515 nm as an electrochromic absorbance shift in intact potato leaves using a double flash differential spectrophotometer. The decay rate of the electrochromic shift in dark‐adapted samples was used to examine the conductance to ions of thylakoid membranes. Heat stress (39.5 °C for 15 min) was found to accelerate drastically the electric field decay, with the half decay time falling from more than 200 ms to less than 45 ms. Heat‐induced acceleration of the electric field breakdown was insensitive to the PSII electron donor Hydroxylamine and to the ATPase inhibitor dicyclohexylcarbodiimide (DCCD), thus indicating that it reflects an increase in thylakoid membrane permeability after heat stress. This phenomenon did not involve peroxidative damage of membrane lipids. Acceleration of the electric field relaxation exhibited the same temperature dependence as that of PSII deactivation, suggesting that the ionic permeability of thylakoid membranes is one of the most heat‐sensitive components of the photosynthetic apparatus. When potato leaves were infiltrated with 100 mol m−3 ascorbate (in a buffer of pH 5), there was massive conversion of the carotenoid violaxanthin to zeaxanthin. This change in carotenoid composition protected thylakoid membranes against heat‐induced changes in permeability, as revealed by the maintenance of a slow decay of the 515 nm absorbance change after heat stress. No such effect was observed after treatments which did not induce the vio‐laxanthin‐to‐zeaxanthin conversion: leaf infiltration with 0 mol m−3 ascorbate (at pH 5 or 8), 100 mol m−3 ascorbate at pH 8 or 100 mol m−3 ascorbate +5 mol m−3 dithiothreitol at pH 5. Increased stability of the permeability properties of thylakoid membranes was also observed after a mild heat treatment (2 h at 35 °C). The data presented suggest that de‐epoxidized xanthophylls in vivo stabilize thylakoid membranes and protect thylakoids against heat‐induced disorganization.

Can estrogens diminish exercise induced muscle damage?

Estrogens are female sex hormones that may also protect against peroxidative damage of membrane lipids and low density lipoproteins (LDL). Studies have reported that female rats have greater protection against free radical induced lipid peroxidation and muscle damage consequent to exercise than do male rats. It has been suggested that the lower susceptibility to exercise induced oxidative stress and muscle membrane disruption of female rats may be due primarily to the antioxidant and membrane stabilizing properties of estrogens. Studies on humans have indicated that the lower incidence of atherosclerosis seen in premenopausal females in comparison to males is due at least in part to the ability of estrogens to diminish LDL peroxidation. However, there is little evidence as to the potential of estrogens to protect human females from free radical induced peroxidation and muscle damage due to exercise. This paper reviews the evidence for membrane stabilization potential of estrogens and their possible mechanisms, and speculates as to the potential significance of this for human exercise.

Changes in Lipid Peroxidation and Lipolytic and Free-Radical Scavenging Enzyme Activities during Aging and Sprouting of Potato (Solanum tuberosum) Seed-Tubers.

Previous research has shown that cell membranes of potato (Solanum tuberosum L. cv Russet Burbank) seed-tubers lose integrity between 7 and 26 months of storage (4[deg]C, 95% relative humidity), and this loss coincides with a significant decrease in growth potential. The age-induced decline in membrane integrity is apparently due to increased peroxidative damage of membrane lipids. Malondialdehyde (MDA) and ethane concentrations (sensitive markers of lipid peroxidation and membrane damage) increased in seed-tuber tissues with advancing age. Moreover, in vivo ethane production from discs of cortex tissue from 13- and 25-month-old seed-tubers was 87% greater (on average) than that from discs from 1-month-old tubers. Calcium suppressed ethane production from all ages of tissue discs, and the effect was concentration dependent. Linoleic acid enhanced ethane production from 5- and 17-month-old tubers by 61 and 228%, respectively, suggesting that older tissue may contain a higher free-radical (FR) titer and/or lower free polyunsaturated fatty acid content. In addition, throughout plant establishment, the internal ethane concentration of older seed-tubers was 54% higher than that of younger seed-tubers. MDA concentration of tuber tissue declined by about 65% during the initial 7 months of storage and then increased 267% as tuber age advanced to 30 months. The age-induced trend in tuber reducing sugar concentration was similar to that of MDA, and the two were linearly correlated. The age-dependent increase in reducing sugars may thus reflect peroxidative degeneration of the amyloplast membrane, leading to increased starch hydrolysis. Compared with 5-month-old seed tubers, 17- and 29-month-old seed-tubers had significantly higher levels of lipofuscin-like fluorescent compounds (FCs), which are produced when MDA reacts with free amino acids. Age-dependent increases in MDA, ethane, and FCs were not associated with higher activities of phospholipase and lipoxygenase in tissue from older tubers. In fact, 8-month-old seed-tubers had significantly higher activities of these enzymes than 20-month-old seed-tubers. However, the activities of superoxide dismutase, peroxidase, and catalase in 20-month-old tubers were substantially higher out of storage, and increased at a faster rate during plant establishment, than in 8-month-old seed-tubers. Collectively, these results suggest that a gradual build-up of FRs leads to peroxidative damage of membrane lipids during aging of potato seed-tubers.

Chemiluminescent simultaneous determination of phosphatidylcholine hydroperoxide and phosphatidylethanolamine hydroperoxide in the liver and brain of the rat.

The quantification of phospholipid hydroperoxides in biological tissues is important in order to know the degree of peroxidative damage of membrane lipids. For this purpose, optimal conditions for the chemiluminescent simultaneous assay of phosphatidylcholine hydroperoxide (PCOOH) and phosphatidylethanolamine hydroperoxide (PEOOH) in rat liver and brain were determined. A chemiluminescence detection-high performance liquid chromatography (CL-HPLC) method that incorporates cytochrome c and luminol as a post-column hydroperoxide-specific luminescent reagent was used (Miyazawa et al. 1987. Anal. Lett. 20: 915-925; Miyazawa. 1989. Free Radical Biol. Med. 7: 209-217). An n-propylamine-bound silica column with hexane-2-propanol-methanol-water 5:7:2:1 (v/v/v/v) (flow rate 1.0 ml/min) as eluant was used to determine both PCOOH and PEOOH, which were separated from each other and from other lipids and lipid-soluble antioxidants. High reproducibility and sensitivity as low as 10 pmol hydroperoxide-O2 were observed with a mixture of 10 micrograms/ml cytochrome c and 2 micrograms/ml luminol in 50 mM borate buffer (pH 10.0, flow rate 1.1 ml/min) as luminescent reagent and a post-column mixing joint temperature of 40 degrees C. Using the established analytical conditions, it was confirmed that both PCOOH (1324 +/- 122 pmol/g liver, 114 +/- 18 pmol/g brain, mean +/- SD) and PEOOH (728 +/- 89 pmol/g liver, 349 +/- 60 pmol/g brain, mean +/- SD) are present in the liver and brain of Sprague-Dawley rats bred on a slightly modified AIN-76A semisynthetic diet for 3 months. The phospholipid hydroperoxide content in the rat liver was shown to be affected by dietary oils, but not significantly affected in the brain.

Participation of lipid peroxidation in the loss of hepatic drug-metabolizing activities in experimental fascioliasis in the rat

Fascioliasis causes a dramatic decrease in drug-metabolizing ability of the hepatic monooxygenase (MFO) and glucuronosyltransferase (GT) enzyme systems in the rat. The present study was undertaken to determine whether lipid peroxidation is involved in the enzymatic loss. Peroxidative damage of membrane lipids (as assessed by the tissue content of malonic dialdehyde, MDA, and the diene conjugation absorption in microsomal membranes) was found to occur over the entire course of the liver infection (concomitant to a decrease in glutathione levels), and to different degrees in relation to the various steps of the parasite cycle. The onset (MDA six times the controls; ΔE 1% = 1·55 at the 20th day) coincides with the beginning of the loss of MFO (− 30%) and GT (− 20% at the 20th day), and peaks between the 30th and 40th day (MDA eight times the controls; ΔE 1% = 1·96), when the loss in the enzyme activities is maximal (MFO − 60 70% ; GT- 65 95% ). There was a strict correlation at all the observation times between the extent of lipid peroxidation and the decrease in drug metabolizing ability: this supports the view that lipid peroxidation is the major agent in the impairment of MFO and GT enzyme activities, and very likely in the initiation of the pathological degeneration of the liver tissue. As evidenced by histological examination, the phagocytic response of the liver tissue to the parasite invasion and growth leads to oxidative stress, which is the causative agent in the initiation and development of lipid peroxidation.

The mechanism of toxic action of hyperbaric oxygenation on the mitochondria of rat-heart cells

Hyperbaric oxygenation of the whole animal was examined with respect to changes in mitochondria from heart cells. Accumulation of conjugated dienes, decrease of unsaturated fatty acids and changes in phospholipid pattern of the mitochondrial membrane indicate peroxidative damage of membrane lipids during oxygen stress. Hyperoxia induces increased activities of Superoxide dismutase, catalase and glutathione peroxidases, all enzymes protecting mitochondria from deleterious effects of reactive oxygen species. From the multiplicity of parameters related to pathophysiological effects of O 2 we inferred on increased formation rates of toxic oxygen species involving superoxide as the initial step in biological activation of O 2. The K m for superoxide formation was 550 μM, ranging above physiological oxygen levels by a factor of 11. Thus, the mechanism by which hyperoxia might affect stimulation of superoxide formation is discussed on the basis of enhanced Michaelis-Menten kinetics due to elevated oxygen levels in the heart tissue. The onset of the membrane damage is the first event in hyperbaric O 2 toxicity. Despite a clear induction, activities of protecting enzymes seem to be ‘swamped’ by raising oxygen concentration above normal.