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PubMed1994

Effect of 21-aminosteroid lipid peroxidation inhibitor, U74006F, in the rat middle cerebral artery occlusion model.

The aim of this study was to evaluate the effect of 21-aminosteroid lipid peroxidation inhibitor, U74006F, on ischaemic brain tissue damage using the rat middle cerebral artery occlusion model. Under anaesthesia, the left middle cerebral artery was exposed without cutting the dura mater via a subtemporal craniotomy, under an operating microscope. Photo-illumination (wave length; 540 nm) was applied to the middle cerebral artery and then rose bengal (20 mg/kg) was administered intravenously. The middle cerebral artery was completely occluded by thrombus about 6 min after the administration of rose bengal. U74006F (1.0 mg/kg) was then injected intravenously just after the cessation of illumination. Twenty four hours after the operation, the extent of ischaemic damage was measured by magnetic resonance imaging technique. After measuring the extent of ischaemic damage, the brain was immediately removed from animals treated with or without U74006F for determination of lipid peroxidation, and the generation of free arachidonic acid in the brain. U74006F significantly (P < 0.01) reduced the size of ischaemic damage. Twenty-four hours after the operation, lipid peroxidation and the concentration of free arachidonic acid in the left hemisphere (infarction side) were significantly (P < 0.05) higher than in the right hemisphere. U74006F significantly (P < 0.05) decreased the content of lipid peroxidation products and free arachidonic acid. There was a significant (P < 0.05) correlation between the extent of ischaemic damage and the concentration of lipid peroxidation products in the left hemisphere 24 h after the operation. In conclusion, U74006F might reduce the extent of ischaemic damage by inhibiting lipid peroxidation in the brain, thus minimizing oxidative damage to neural tissues.

Animals↗
PubMed1985

Organic hydroperoxide-induced lipid peroxidation and cell death in isolated hepatocytes.

Organic hydroperoxides such as tert-butyl hydroperoxide (TBHP) are cytotoxic to suspensions of isolated hepatocytes. The exact mechanism of toxicity is unknown but may involve peroxidation of cellular lipids, alkylation of cellular macromolecules, or alterations in cellular calcium homeostasis. These studies were designed to examine lipid peroxidation as a mechanism of organic hydroperoxide-induced cell death. Hepatocytes isolated from mice were more susceptible to the cytotoxic effects of TBHP than were rat hepatocytes. TBHP-induced cell death was preceded by malondialdehyde formation which was also greater in mouse than rat hepatocytes. Species differences in lipid peroxidation were due to intrinsic properties of hepatocyte membranes as lipids isolated from mouse liver and peroxidized with iron/ascorbate formed approximately eightfold more malondialdehyde than lipids isolated from rat liver. Initiation of lipid peroxidation in mouse and rat hepatocytes with iron/ascorbate caused the formation of malondialdehyde equal to that seen with TBHP and a slight depletion of cellular GSH. As with TBHP, malondialdehyde formation induced by iron/ascorbate was greater in mouse than in rat hepatocytes. However, iron/ascorbate had no effect on hepatocyte viability or morphology from either species. Furthermore, TBHP-induced malondialdehyde and ethane formation in isolated rat hepatocytes were completely blocked by promethazine whereas cell toxicity was altered only slightly. Therefore, these data do not support a role for lipid peroxidation in the acute cytotoxicity of TBHP to suspensions of isolated rat hepatocytes.

Animals↗
PubMed1991

No relationship between the age-related decrease in prostacyclin production and the level of intracellular lipid peroxidation in human umbilical vein endothelial cells in culture.

Some investigators have speculated that a decrease in prostacyclin production observed during ageing of endothelial cells is caused by an increase in intracellular lipid peroxide. We checked this speculation using an in vitro model to study the ageing of human vascular endothelial cells. For this purpose we determined the levels of intracellular lipid peroxide of endothelial cells at various culture ages, and found that the level of intracellular lipid peroxidation did not increase during in vitro ageing. Amounts of intracellular lipid peroxide also differed depending on the growth phase, the addition of heparin and the strain of endothelial cells, but the cells producing prostacyclin at a low level did not necessarily contain larger amounts of intracellular lipid peroxide. Therefore, we postulate that the age-related decrease in prostacyclin production is not due to an increase in the amount of intracellular lipid peroxide as a function of age.

Cells, Cultured↗
PubMed1984

Adriamycin stimulates NADPH-dependent lipid peroxidation in liver microsomes not only by enhancing the production of O2 and H2O2, but also by potentiating the catalytic activity of ferrous ions.

The antitumor drug, adriamycin, enhances NADPH-dependent lipid peroxidation in liver microsomes via the formation of superoxide anion radicals (O2) and hydrogen peroxide (H2O2). In the presence of metal ions additional reactive species are generated, causing stimulation of lipid peroxidation. However, in this study it was found that the stimulation of NADPH-dependent lipid peroxidation by adriamycin was not only affected by the production of O2 and H2O2. Adriamycin also enhances the catalysis by metal ions of the formation of those reactive oxygen species which initiate peroxidation. This was inferred from the fact that adriamycin stimulated malondialdehyde production at low ferrous ion concentrations, whereas at high ferrous ion concentrations no stimulation was found. Additional evidence was found in experiments in which the enzymic redox cycle of adriamycin in microsomes was abolished by heat-inactivation of the microsomes, and O2 and H2O2 were only produced with xanthine and xanthine oxidase. In this case in the presence of ferrous ions, adriamycin stimulated lipid peroxidation.

Animals↗
PubMed1992

Mechanism of the increase in lipid peroxide induced by cisplatin in the kidneys of rats.

To clarify the mechanism where by cisplatin induces increases in lipid peroxide, we examined the effects of antioxidants on changes in the activity of lipid peroxidation protecting enzymes in the kidneys of rats after cisplatin administration. alpha-Tocopherol and glutathione (GSH) significantly depressed lipid peroxidation in the kidneys of cisplatin-treated rats on the 4th day after cisplatin administration, and GSH depressed the increases in blood urea nitrogen levels induced by cisplatin. Thus, GSH appeared to reduce cisplatin-induced nephrotoxicity. However, alpha-tocopherol and GSH had no effect on the significant decrease in the activity of lipid peroxidation protecting enzymes induced in the kidney after cisplatin treatment. These results showed that lipid peroxide produced by cisplatin had no effect on these enzymes, suggesting that the increases of lipid peroxide were a result of the cisplatin-induced reduction in the activity of these enzymes.

Animals↗
PubMed1985

Consecutive action of phospholipase A2 and glutathione peroxidase is required for reduction of phospholipid hydroperoxides and provides a convenient method to determine peroxide values in membranes.

The purpose of this study was to investigate the ability of selenium-dependent glutathione peroxidase to reduce phospholipid hydroperoxides in membrane bilayers and to develop a method to measure the peroxide content of phospholipids. Phospholipid hydroperoxides were synthesized by photooxidation of 1-palmitoyl 2-linoleoyl phosphatidylcholine and characterized by gas chromatography-mass spectrometry. Phospholipid hydroperoxides in phosphatidylcholine bilayers showed no detectable reactivity with Se-dependent glutathione peroxidase (the reaction is at least 65,000 times slower than with an available hydroperoxide). However, after the phospholipid hydroperoxides were preincubated with phospholipase A2, the free fatty acid hydroperoxides became available as a substrate for Se-dependent glutathione peroxidase. The enzyme assay can be used for convenient determination of peroxide values in phospholipids at the 1 nmole level and free fatty acid hydroperoxides can be distinguished from phospholipid hydroperoxides by omitting phospholipase A2. The accuracy of the enzymatic method was confirmed using an improved colorimetric chemical assay to measure peroxide values of phospholipid hydroperoxides to the same sensitivity. The chemical assay was not linear in the presence of high levels of lipid, but at low levels of lipid the peroxide values of phospholipid hydroperoxides measured by both methods agreed to within 1%. Since high levels of lipid inhibited the chemical assay, the enzyme assay is more accurate for determination of peroxides in membranes and tissues. The possible role of phospholipase deficiencies as a causal factor in degenerative diseases thought to be due to lipid peroxidation, such as Neuronal Ceroid Lipofuscinosis (Battens disease), is discussed.

Colorimetry↗
PubMed1995

Lipid peroxidation contributes to age-related membrane rigidity.

The aim of this work was to assess the relative contributions of lipid peroxidation and cholesterol content to the increase in membrane rigidity observed during senescence. Membrane fluidity was manipulated through exposure to peroxidized or cholesterol-loaded liposomes. Small unilamella liposomes were prepared and either peroxidized by Fe(++)-ADP-ascorbic acid or loaded with cholesterol. After incorporation of the liposomes into rat liver microsomal membranes, membrane fluidity was quantitated by measuring changes in polarization. Membranes exhibited a greater sensitivity to peroxidation than cholesterol in that incorporation of peroxidized liposomes induced microsomal membrane rigidity substantially more than did cholesterol-loaded liposomes. Thus it is proposed, based on data from the present and earlier studies, that membrane fluidity can be modulated readily by lipid peroxidation of membrane phospholipids, irrespective of the influences of cholesterol. These results support the proposal that alterations of lipid structure are more potent and effective than compositional changes in cholesterol in inducing age-related increases in membrane rigidity.

Aging↗
PubMed1991

Ultraviolet-treated lipoproteins as a model system for the study of the biological effects of lipid peroxides on cultured cells. III. The protective effect of antioxidants (probucol, catechin, vitamin E) against the cytotoxicity of oxidized LDL occurs in two different ways.

Comparison of the protective effect of three antioxidants (from three different chemical classes) against cell injury due to LDL oxidation, allowed us to clearly discriminate between two different lines of defence. The ultraviolet-induced lipid peroxidation of LDL was strongly inhibited by 10 mumol/l catechin and 25 mumol/l probucol, but only poorly by 100 mumol/l vitamin E. The ultraviolet-treated LDL protected by catechin or probucol (i.e. LDL irradiated by ultraviolet in the presence of effective concentrations of antioxidants inhibiting the lipid peroxidation) were much less 'cytotoxic' than unprotected ultraviolet-treated LDL. In contrast, LDL treated by ultraviolet in the presence of 100 mumol/l vitamin E were 'cytotoxic' similarly to unprotected LDL. The level of 'cytotoxicity' of LDL treated by ultraviolet in the presence of antioxidants (protected ultraviolet-treated LDL) was well correlated with their content in lipid peroxidation markers. Therefore these markers can be useful for predicting the 'cytotoxicity' of oxidized LDL and subsequently the protective effect of the tested antioxidants. The 'cytotoxicity' of unprotected ultraviolet-treated LDL (i.e. LDL irradiated by ultraviolet in the absence of exogenous antioxidant) can be effectively blocked by preincubation of the cells with antioxidants. Catechin (10 mumol/l) and vitamin E (100 mumol/l) are very effective cytoprotective agents, whereas probucol (up to 50 mumol/l) was completely ineffective under these experimental conditions. The cytoprotective effect of vitamin E was associated to a complete inhibition of the cellular TBARS formation induced by ultraviolet-treated LDL, whereas the cytoprotective effect of catechin was relatively independent on the TBARS inhibition. All these results showed that: (1) probucol (25 mumol/l) is very effective to prevent lipid peroxidation of LDL and their subsequent 'cytotoxicity', but it cannot protect cells against the 'cytotoxicity' of previously oxidized LDL; (2) vitamin E (100 mumol/l) prevents poorly the ultraviolet-induced lipid peroxidation of LDL, but is able to block simultaneously the cellular oxidative stress and the 'cytotoxicity' induced by previously oxidized LDL; and (3) catechin (10 mumol/l) exhibited two types of protective effects: it inhibits the lipid peroxidation of LDL (and their subsequent 'cytotoxicity') and very effectively protects the cells against 'toxicity' of previously oxidized LDL (with only little inhibition of the cellular oxidative stress).(ABSTRACT TRUNCATED AT 400 WORDS)

Antioxidants↗
PubMed2004

Possible link between glycated hemoglobin and lipid peroxidation in hyperthyroidism.

BACKGROUND: Glycated hemoglobin (HbA1C) levels are enhanced by elevated glucose concentrations. Glycation of hemoglobin is also modulated by lipid peroxides, ascorbic acid and reduced glutathione (GSH). We determined the strength of the relationships among these variables in a group of hyperthyroid patients. METHODS: Twenty-two untreated hyperthyroid patients and 17 healthy controls were recruited for the study. Whole blood GSH, HbA1C, plasma lipid peroxides, ascorbic acid and fasting glucose were analyzed in both the groups. Direct and partial correlation analysis was performed to explore the possible relationships between these variables. RESULTS: In hyperthyroid patients, HbA1C and lipid peroxides levels were found to be significantly increased than the controls. Ascorbic acid and GSH were decreased significantly in the test group when compared with the healthy control group. With partial correlation analysis, fasting glucose and lipid peroxides were found to have a significant positive correlation with HbA1C. Ascorbic acid and GSH showed no significant association with HbA1C levels. CONCLUSION: These data suggest that HbA1C levels are closely associated with fasting glucose and lipid peroxides in hyperthyroid patients. Therefore, serum lipid peroxides level should be kept in mind while interpreting HbA1C as a long-term glycemic index in hyperthyroid cases.

Adolescent↗
PubMed2005

Lipid peroxidation measurement by thiobarbituric acid assay in rat cerebellar slices.

Lipid peroxidation by reactive oxygen species (ROS) is known to be involved in the damaging mechanism of several acute and chronic brain disorders. The most prominent and currently used assay as an index for lipid peroxidation products is the thiobarbituric acid assay (TBA test). It is based on the reactivity of an end product of lipid peroxidation, malondialdehyde (MDA) with TBA to produce a red adduct. However, it is known that the MDA levels are frequently overestimated, that the reaction lacks specificity and mainly reflects the susceptibility of brain tissue to the generation and degradation of newly formed lipid hydroperoxides under the TBA test conditions. The present paper shows that artifactual lipid peroxidation by TBA test conditions can be prevented and that the MDA level overestimation can be minimized in cerebellar slices. This can be done by incubating the slices in a continuous tissue perfusion system, by adding butylated hydroxytoluene (BHT) to the homogenization solutions and by carrying out the assay anaerobically on deproteinizated supernatants of cerebellar slice homogenates. The present research also showed that lipid peroxidation products generated during incubation of the slices by hydrogen peroxide (H2O2) could be measured without artifactual interference by the TBA test conditions.

Animals↗
PubMed1999

Low density lipoprotein immunoapheresis does not increase plasma lipid peroxidation products in vivo.

Extracorporeal elimination of low density lipoprotein (LDL) is frequently used in drug-resistant hypercholesterolemia. LDL-immunoapheresis selectively removes LDL and lipoprotein(a) [Lp(a)] from plasma. Lipid peroxidation is one unwanted side effect, that occurs during extracorporeal plasma treatment. The purpose of this study was to investigate the effect of LDL immunoapheresis on lipid peroxidation. Before and after a single LDL-immunoapheresis treatment, plasma concentrations of lipid hydroperoxides, determined with two different spectophotometric assays, thiobarbituric acid-reacting substances (TBARS), determined spectrophotometrically and malondialdehyde (MDA), determined by an MDA-TBA/HPLC method, were measured in 13 hypercholesterolemic patients. In addition MDA was also determined in the eluate of the apheresis column. Before treatment, plasma cholesterol and LDL cholesterol concentrations were significantly higher in patients than in healthy control subjects, as were the lipid peroxidation products. LDL-immunoapheresis treatment of the patients led to significant decreases in total cholesterol (69+/-8%), LDL-cholesterol (79+/-7%), HDL-cholesterol (35+/-17%), triglycerides (38+/-21%), apolipoprotein-B (77+/-6%), apolipoprotein-A1 (25+/-5%) and Lp(a) concentrations (76+/-10%). Changes in plasma lipid peroxide concentrations (17+/-8 nmol/l before vs. 14+/-5 nmol/l after treatment) were not significant, neither were those in TBARS (3. 0+/-2.6 micromol/l vs. 2.3+/-1.3 micromol/l) or MDA concentrations (1.03+/-0.17 micromol/l vs. 1.0+/-0.20 micromol/l). Patients with high baseline values showed a decrease, whereas others did not. MDA was present (0.57+/-0.13 micromol/l) in the eluate of the apheresis column, suggesting that, along with LDL, lipid peroxidation products are also removed. From these results we conclude that a single LDL-immunoapheresis treatment effectively reduces LDL and Lp(a) in the absence of increases in plasma lipid peroxidation products.

Adult↗
PubMed1998

Peroxidative damage to cardiac mitochondria: cytochrome oxidase and cardiolipin alterations.

Rat heart mitochondrial membranes exposed to the free radicals generating system tert-butylhydroperoxide/Cu2+ undergo lipid peroxidation as evidenced by the accumulation of thyobarbituric acid reactive substances. Mitochondrial lipid peroxidation resulted in a marked loss of both cytochrome c oxidase activity and cardiolipin content. The alterations in the properties of cytochrome c oxidase were confined to a decrease in the maximal activity (Vmax) with no change in the affinity (Km) with respect to the substrate cytochrome c. Various lipid soluble antioxidants could prevent the lipid peroxidation reaction and the associated loss of cytochrome c oxidase activity. External added cardiolipin but no other phospholipids, nor peroxidized cardiolipin was able to prevent the loss of cytochrome oxidase activity induced by lipid peroxidation. These results establish a close correlation between oxidative damage to cardiolipin and alterations in the cytochrome oxidase activity and may prove useful in probing molecular mechanism of free radicals induced peroxidative damage of mitochondria which has been proposed to contribute to aging and to chronic degenerative diseases.

Animals↗
PubMed1999

Nitroglycerin as a nitric oxide donor accelerates lipid peroxidation but preserves ventricular function in a canine model of orthotopic heart transplantation.

BACKGROUND: Nitric oxide has cardioprotective effects through several mechanisms. However, nitric oxide may have deleterious effects in the presence of superoxide because it is converted to peroxynitrite, which then initiates lipid peroxidation. Using a canine model of orthotopic heart transplantation, we examined whether adding an organic nitric oxide donor, nitroglycerin, to preservation solution elicits lipid peroxidation after reperfusion and causes deleterious effects on coronary endothelial function and left ventricular function. METHODS AND RESULTS: The donor heart was preserved for 24 hours in cold University of Wisconsin solution with nitroglycerin (0.1 mg/mL) supplementation (group NTG, n = 8) or in standard University of Wisconsin solution (group C, n = 8). After reperfusion, changes of coronary resistance were measured during the infusion of acetylcholine (0.1 mg/min) and of sodium nitroprusside (1 mg/min), and percent coronary relaxation was calculated. Left ventricular function was evaluated by pressure-volume relations with the use of a conductance catheter, thereby deriving the slopes of end-systolic pressure-volume relation, stroke work-end-diastolic volume relation, and maximum rate of change of left ventricular pressure-end-diastolic volume relation. Serum lipid peroxide level was measured. Percent coronary relaxation was similar for the 2 groups. The slopes of end-systolic pressure-volume relation, stroke work-end-diastolic volume relation, and maximum rate of change of left ventricular pressure-end-diastolic volume relation in group NTG were significantly higher than those in group C. On the other side, serum lipid peroxide level in group NTG was significantly higher than that in group C. CONCLUSIONS: Nitroglycerin may have detrimental effects evidenced by the increase in lipid peroxidation, which implied peroxynitrite formation. However, the overall effect of nitroglycerin was cardioprotective. Although the exact mechanism is yet to be clarified, the superb cardioprotective effect of nitroglycerin overwhelms the exaggeration of lipid peroxidation.

Animals↗
PubMed1999

Effect of aminoguanidine on lipid peroxidation in streptozotocin-induced diabetic rats.

Diabetes mellitus is postulated to be associated with increased lipid peroxidation, which may contribute to vascular complications. One potential mechanism of the increased lipid peroxidation in diabetes is lipid-linked advanced glycosylation and oxidation. Aminoguanidine (AMGN), the prototype inhibitor of advanced glycosylation end product (AGE) formation, has been recently shown to prevent oxidative modification of low-density lipoprotein (LDL) in vitro at a moderate concentration. It is unknown whether AMGN may act as an antioxidant against lipid peroxidation under hyperglycemia in vivo. To investigate the in vivo effect of AMGN on lipid peroxidation in diabetes, we administered AMGN (1 g/L in drinking water) or vitamin E (400 mg/d for 5 d/wk) to streptozotocin (STZ)-induced diabetic rats for 9 weeks and measured plasma lipid hydroperoxides by ferrous oxidation with xylenol orange II (FOX method) and red blood cell (RBC) membrane malondialdehyde (MDA) and related aldehydes as thiobarbituric acid-reactive substances (TBARS). Plasma lipid hydroperoxide was higher in STZ-induced diabetic rats versus control rats (mean +/- SD, 7.53 +/- 2.03 v 5.62 +/- 0.44 micromol/L, P < .05; n = 8 to 14). RBC membrane TBARS were also higher in STZ-induced diabetic rats than in control rats (2.67 +/- 0.46 v 1.81 +/- 0.19 nmol/mL, P < .05). Plasma lipid hydroperoxide was lower in AMGN-treated (6.23 +/- 0.59 micromol/L, P < .05) and vitamin E-treated (5.29 +/- 0.27 micromol/L, P < .05) diabetic rats than in untreated diabetic rats. RBC membrane TBARS were also lower in AMGN-treated (1.93 +/- 0.12 nmol/mL, P < .05) diabetic rats than in untreated diabetic rats. There was no significant difference in plasma glucose, cholesterol, and triglyceride levels among diabetic groups. Although the mechanism(s) of action of AMGN on lipid peroxidation in vivo should be studied further, these results suggest that AMGN may have an additional beneficial effect as an antioxidant against lipid peroxidation in a prevention trial for diabetic vascular complications.

Animals↗
PubMed1983

Benzoyl peroxide: percutaneous penetration and metabolic disposition. II. Effect of concentration.

The effect of drug concentrations of 2.5%, 5%, and 10% upon the transepidermal penetration of 14C-benzoyl peroxide in a lotion vehicle was assessed in excised human skin and in vivo in the rhesus monkey. In vitro, penetration of benzoyl peroxide was concentration-dependent, both as to rate and to amount, as measured by the hourly recovery of the metabolite, benzoic acid, from the dermal side of the model. In vivo, the higher the concentration of benzoyl peroxide applied, the greater the amount absorbed, as indicated by the urinary excretion of 14C-benzoic acid. Metabolic disposition of benzoyl peroxide, in turn, was unaffected by drug concentration. In all instances, the benzoyl peroxide absorbed was excreted rapidly in urine as benzoic acid; no hippuric acid was detected at any time. We conclude that (1) use of the excised human skin model for this compound can provide useful data in studies of the effects of vehicle and concentration on topical drug delivery, (2) the transepidermal delivery of benzoyl peroxide, but not its metabolic disposition, is concentration-dependent, and (3) the renal clearance of the systemically absorbed drug is so rapid that it precludes passage through the liver--therefore, no systemic toxicity due to drug accumulation can be expected.

Administration, Topical↗
PubMed2000

Attenuation of benzoyl peroxide-mediated cutaneous oxidative stress and hyperproliferative response by the prophylactic treatment of mice with spearmint (Mentha spicata).

The modulating effect of spearmint (Mentha spicata) on benzoyl peroxide-induced responses of tumor promotion in murine skin was investigated. Benzoyl peroxide (BPO) is an effective cutaneous tumor promoter acting through the generation of oxidative stress, induction of ornithine decarboxylase activity and by enhancing DNA synthesis. BPO treatment (20 mg/animal) increased cutaneous microsomal lipid peroxidation and hydrogen peroxide generation. The activity of cutaneous antioxidant enzymes, namely catalase, glutathione peroxidase, glutathione reductase and glutathione S-transferase, was decreased and the level of cutaneous glutathione was depleted. BPO treatment also induced the ornithine decarboxylase activity and enhanced the [3H]thymidine uptake in DNA synthesis in murine skin. Prophylactic treatment of mice with spearmint extract (10, 15 and 20 mg/kg) 1 hr before BPO treatment resulted in the diminution of BPO-mediated damage. The susceptibility of cutaneous microsomal membrane to lipid peroxidation and hydrogen peroxide generation was significantly reduced (P < 0.05 ). In addition, depleted levels of glutathione, inhibited activity of glutathione dependent and antioxidant enzymes were recovered to a significant level (P < 0.01, P < 0.05 and P < 0.01, respectively). Similarly, the elevated ornithine decarboxylase activity and enhanced thymidine uptake in DNA synthesis was inhibited significantly (P < 0.05 ) in a dose-dependent manner. The protective effect of spearmint was dose dependent in all parameters. The result suggests that spearmint is an effective chemopreventive agent that may suppress BPO-induced cutaneous oxidative stress, toxicity and hyperproliferative effects in the skin of mice.

Animals↗
PubMed2003

Induction of lipid peroxidation in biomembranes by dietary oil components.

Prooxidant formation and resulting lipid peroxidation are supposed to be involved in the pathogenesis of various diseases including cancer. Cancer risk is possibly influenced by the composition of diet with high intake of fat and red meat being harmful and high consumption of fruits and vegetables being protective. Since dietary oils may contain potential prooxidants, the aim of the present study was to prove (i) whether oxidative stress in biomembranes may be induced by dietary oils and if, (ii) which impact it has on the viability and proliferation of cultured colon (carcinoma) cells. Lipid hydroperoxide content in dietary oils increased after heating. Linoleic acid hydroperoxide (LOOH) and/or oils with different hydroperoxide contents induced lipid peroxidation in liposomes, erythrocyte ghosts and colon cells. Upon incubation with liposomes, both LOOH and heated oil induced lipid peroxidation only in the presence of iron and ascorbate. LOOH was sufficient to start lipid peroxidation of erythrocyte ghosts. LOOH incorporates into the lipid bilayer decreasing membrane fluidity and initiating lipid peroxidation in the lipid phase. When cultured cells (IEC18 intestinal epithelial cells, SW480 and HT29/HI1 colon carcinoma cells) were exposed to LOOH, they responded by cell death both via apoptosis and necrosis. Cells with higher degree of membrane unsaturation were more susceptible and antioxidants (vitamin E and selenite) were protective indicating the involvement of oxidative stress. Thus, peroxidation of biomembranes can be initiated by lipid hydroperoxides from heated oils. Dietary consumption of heated oils may lead to oxidative damage and to cell death in the colon. This may contribute to the enhanced risk of colon cancer due to regenerative cell proliferation.

Animals↗
PubMed2003

Protection of cells from menadione-induced apoptosis by inhibition of lipid peroxidation.

Menadione is a commonly used compound that causes oxidative stress. We investigated the influence of lipid peroxidation on the apoptotic response of mouse myogenic C2C12 cells following menadione-induced oxidative stress. The presence of hypodiploid cells and phosphatidylserine translocation were assayed to detect apoptotic cells. Menadione at 10-40 micro M induced cell apoptosis. Menadione at dose of 80 micro M induced both apoptosis and necrosis. At a 160 micro M dosage, menadione induced cell necrosis. Caspase 3 activation is required for menadione-induced apoptosis. Incubation of cells with 40 micro M menadione resulted in the depletion of cellular glutathione and increased lipid peroxidation. Pre-treatment of cells with cysteine suppressed the menadione-induced apoptosis and prevented changes in reactive oxygen species levels, glutathione levels and lipid peroxidation. Pre-treatment of cells with deferoxamine mesylate, an iron chelator, also reduced both menadione-induced apoptosis and lipid peroxidation. However, this did not prevent menadione-induced glutathione depletion. Thus, the inhibition of lipid peroxidation by deferoxamine mesylate prevented apoptosis even though cellular glutathione remained depleted. Our data suggest that menadione-induced apoptosis is directly linked to iron-dependent lipid peroxidation.

Animals↗