Effect of Milk Whey and Its Fermentation Products by Lactic Acid Bacteria on Mitochondrial Lipid Peroxide and Hepatic Injury in Bile Duct-ligated Rats

The study was carried out to assess whether bovine milk whey and its products fermented by lactic acid bacteria could ameliorate the lipid peroxidation of hepatic mitochondria associated with cholestatic liver injury due to bile duct ligation. Rats were maintained on one of five diets for 3 weeks before being operated upon and killed 3 weeks after bile duct ligation. The diets included one deficient in vitamin E (control diet) and others supplemented with either 5% milk whey or 5% milk whey fermented with Bifidobacterium longum (B. longum), Lactobacillus acidophilus (L. acidophilus), and Streptococcus salivarius subsp. thermophillus (S. thermophillus). Bile duct-ligated rats, compared with sham-operated rats, had higher organ weights (liver and spleen), higher serum alkaline phosphatase activity, higher serum bilirubin concentration, and higher content of hepatic mitochondrial lipid hydroperoxide. The rats fed on diets containing milk whey fermented with B. longum ameliorated the elevation of organ weights, enzyme activity, bilirubin concentration, and content of mitochondrial lipid hydroperoxide. Milk whey and milk whey fermented with L. acidophilus and S. thermophillus also suppressed the elevation of mitochondrial lipid hydroperoxide, but had no ameliorating effects on organ weights, enzyme activity, and bilirubin concentration. The elevation of serum lipid hydroperoxide was ameliorated in rats fed on diets containing milk whey and milk whey fermented with B. longum and S. thermophillus. The reduction in plasma α-tocopherol due to bile duct ligation was ameliorated in those rats fed on diets containing milk whey fermented with B. longum as well as by S. themophillus. These results suggest that a milk whey fermented with lactic acid bacteria exerts a beneficial effect on free radical-mediated hepatic injury.     

Mitochondrial lipid peroxidation is influenced by dietary factors in early colon carcinogenesis

Oxidative damage to mitochondrial proteins, lipids, and DNA seem to influence the promotion and progression of tumors. High-fat diets and diets high in iron decrease manganese superoxide dismutase activity, a mitochondrial antioxidant, in colon mucosa. Lipid peroxidation products are low in microsomal preparations from colonic mucosa even under peroxide-inducing conditions. However, damage specific to mitochondrial membranes is unknown. This study was designed to investigate dietary lipid and iron effects on fatty acid incorporation and lipid peroxide formation in mitochondrial membranes of colonic mucosa. Male Fischer rats were fed high-fat diets containing either corn oil or menhaden oil with an iron level of either 35 or 535 mg/kg diet. Animals were given two injections of the colon carcinogen, azoxymethane, or saline. Colon tissue was collected 1 and 6 weeks after injections. Mitochondrial and microsomal fractions were prepared for fatty acid analysis and quantitation of lipid peroxidation products. Results showed that lipid composition of both subcellular fractions were influenced by diet. Fatty acid composition of mitochondria differed from microsomes, but overall saturation remained constant. Peroxidation products in mitochondrial membranes were significantly greater than in microsomal membranes. Dietary treatment significantly affected mitochondrial peroxidation in carcinogen-treated animals. Therefore, mitochondria from colon mucosa are more susceptible to peroxidation than are microsomes, dietary factors influence the degree of peroxidation, and the resulting damage may be important in early colon carcinogenesis.     

Oxidative stress and antioxidant status in mouse kidney: effects of dietary lipid and vitamin E plus iron

The purpose of this study was to determine the effects of dietary fat, vitamin E, and iron on oxidative damage and antioxidant status in kidneys of mice. Sixty 1-month-old male Swiss-Webster mice were fed a basal vitamin E-deficient diet that contained either 8% fish oil + 2% corn oil or 10% lard with or without 1 g all-rac-alpha-tocopherol acetate or 0.74 g ferric citrate per kilogram of diet for 4 weeks. Significantly (P < 0.05) higher levels of lipid peroxidation products, thiobarbituric acid reactants (TBAR), and conjugated dienes were found in the kidneys of mice fed with fish oil compared with mice fed lard irrespective of vitamin E status. Mice maintained on a vitamin E-deficient diet had significantly higher renal levels of TBAR, but not conjugated dienes, than the supplemented group. Fish oil fed mice receiving vitamin E supplementation had lower levels of alpha-tocopherol than did mice in the lard fed group. Significantly higher levels of ascorbic acid were also found in the kidneys of mice fed with fish oil than were found in mice fed lard. The levels of protein carbonyls and glutathione (GSH), and activities of catalase, superoxide dismutase, selenium (Se)-GSH peroxidase, and non-Se-GSH peroxidase were not significantly altered by dietary fat or vitamin E. Dietary iron had no significant effect on any of the oxidative stress and antioxidant indices measured. The results obtained provide experimental evidence for the pro-oxidant effect of high fish oil intake in mouse kidney and suggest that dietary lipids play a key role in determining cellular susceptibility to oxidative stress.     

Dietary intrinsic phytate protects colon from lipid peroxidation in pigs with a moderately high dietary iron intake.

High iron consumption has been proposed to relate to an increase in the risk of colon cancer, whereas high levels of supplemental sodium phytate effectively reduce iron-induced oxidative injury and reverse iron-dependent augmentation of colorectal tumorigenesis. However, the protective role of intrinsic dietary phytate has not been determined. In this study, we examined the impact of removing phytate present in a corn-soy diet by supplemental microbial phytase on susceptibility of pigs to the oxidative stress caused by a moderately high dietary iron intake. Thirty-two weanling pigs were fed the corn-soy diets containing two levels of iron (as ferrous sulfate, 80 or 750 mg/kg diet) and microbial phytase (as Natuphos, BASF, Mt. Olive, NJ, 0 or 1200 units/kg). Pigs fed the phytase-supplemented diets did not receive any inorganic phosphorus to ensure adequate degradation of phytate. After 4 months of feeding, liver, colon, and colon mucosal scrapings were collected from four pigs in each of the four dietary groups. Colonic lipid peroxidation, measured as thiobarbituric acid reacting substances (TBARS), was increased by both the high iron (P< 0.0008) and phytase (P< 0.04) supplementation. Both TBARS and F2-isoprostanes, an in vivo marker of lipid peroxidation, in colonic mucosa were affected by dietary levels of iron (P< 0.03). Mean hepatic TBARS in pigs fed the phytase-supplemented, high iron diet was 43%-65% higher than that of other groups although the differences were nonsignificant. Moderately high dietary iron induced hepatic glutathione peroxidase activity (P= 0.06) and protein expression, but decreased catalase (P< 0.05) in the colonic mucosa. In conclusion, intrinsic phytate in corn and soy was protective against lipid peroxidation in the colon associated with a moderately high level of dietary iron.     

Ovarian follicular development, lipid peroxidation, antioxidative status and immune response in laying hens fed fish oil-supplemented diets to produce n-3-enriched eggs

The objective of the present study was to research the effect of feeding laying hens fish oil-supplemented diets to produce n-3-enriched eggs on their ovarian follicular development, serum lipid peroxidation, antioxidative status and immune response. A total of 105 white Bovens hens at 24 weeks of age were housed in cages in an open-sided building under a 16 h light : 8 h dark lighting schedule. Birds were randomly divided into five treatments and were fed, ad libitum, diets containing 0% (control), 1.25%, 2.5%, 3.5% or 5.0% fish oil from 24 to 36 weeks of age. Egg production and weight were recorded. By weeks 35 and 36 of age 15 eggs were taken at random from each treatment to determine the yolk lipid profile and cholesterol content. At the end of the experimental period, 10 females from each treatment were randomly chosen, anaesthetised and killed by decapitation. Ovary and oviduct samples were immediately weighted and ovarian follicles were classified. Serum thiobarbituric acid-reactive substance (TBARS), hepatic TBARS and hepatic glutathione peroxidase (GSH-Px) activity were measured. No clear trend was observed concerning egg production and egg yolk cholesterol. As dietary fish oil levels increased, n-3-polyunsaturated fatty acids (n-3 PUFA) increased, whereas n-6 PUFA tended to decrease in yolk lipids. No negative effects were detected in ovary and oviduct weights, expressed in both absolute terms and relative to body weight. The numbers and total weights of large yellow follicles (LYF) in the ovary were not significantly affected by fish oil supplementation. Low levels (1.25% to 2.5%) of fish oil reduced both plasma and hepatic TBARS and enhanced GSH-Px activity. It is also interesting to note that inclusion of 2.5% fish oil in laying hen diets enhanced the antibody titre in laying hens. Therefore, it could be concluded that inclusion of fish oil in laying hen diets at moderate levels increased the n-3 fatty acids content in eggs, improved antioxidative status, enhanced the antibody response and did not have a negative influence on the different reproductive morphology parameters in laying hens.     

Relationships between lipid peroxidation and anoxia tolerance in a range of species during post-anoxic reaeration

Peroxidation was studied in anoxically treated plant tissues and quantified as conjugated dienes/trienes in the total lipid fraction and as the production of thiobarbituric acid reactive substances (TBARS). Oxidative stress caused by re-exposure of plants to oxygen led to an increase of conjugated diene/triene formation in rhizomes of Iris germanica and roots of wheat ( Triticum aestivum L.) and oats ( Avena sativa L.), and after a long anoxic exposure (45 days) in the rhizomes of the very anoxia tolerant Iris pseudacorus . Second derivative (SD) spectrophotometry of the UV spectrum of lipid extracts confirmed the formation of dienes. However, determination of TBARS in Iris spp. showed no lipid peroxidation in the anoxia tolerant I. pseudacorus . In the rhizomes of the anoxia intolerant I. germanica , elevated levels of TBARS correlated positively with conjugated diene/triene formation. The results suggest that anoxic stress may induce qualitative changes in membrane lipids, as indicated by lipid peroxidation after restoration of aerobic conditions. The rate of lipid peroxidation correlated negatively with anoxic stress tolerance.     

Effects of high-fat,low-cholesterol diets on hepatic lipid peroxidation and antioxidants in apolipoprotein E-deficient mice

The present study describes the effects of several high-fat low-cholesterol antiatherogenic diets on the hepatic lipid peroxidation and hepatic antioxidant systems in apolipoprotein E-deficient mice. Eighty mice were distributed into five groups and fed with regular mouse chow or chow supplemented with coconut, palm, olive and sunflower seed oils. After ten weeks, they were sacrificed and the livers were removed so that lipid peroxidation and -tocopherol concentrations, and superoxide dismutase, glutathione peroxidase and glutathione reductase activities could be measured. The size of the atherosclerotic lesions in the aortas was also measured. Results showed that the diets supplemented with olive oil, palm oil or sunflower seed oil significantly decreased the size of the lesion. However, there was an association between those mice that were on diets supplemented with palm or coconut oils and a significant increase in hepatic lipid peroxidation. This association was not found in animals fed with olive or sunflower seed oils, the diets with the highest content of vitamin E. The dietary content of vitamin E was significantly correlated (r = 0.98; p < 0.05) with the hepatic concentration of this compound. Our study suggests that the high content of vitamin E in olive oil or sunflower seed oil may protect from the undesirable hepatotoxic effects of high-fat diets in apo E-deficient mice and that this should be taken into account when these diets are used to prevent atherosclerosis.     

Dietary lipid level influences fatty acid profiles, tissue composition, and lipid peroxidation of soft-shelled turtle, Pelodiscus sinensis

Dietary lipids containing equal portions of soybean oil and fish oil were fed to juvenile Chinese soft-shelled turtle, Pelodiscus sinensis, at supplementation level of 0 to 15% for 8 weeks. Tissue fat contents of turtles increased when dietary lipid concentration increased. Fatty acid profiles for turtles fed diets supplemented with 6% or higher levels of lipids were similar to those in dietary lipids. On absolute value basis, fatty acids of 14-, 16-, and 18-carbons in muscle of turtles fed diet without lipid supplementation were higher than those in the initial turtle muscle. Among them, C16:1 and C18:1 was approximately 4 and 2 fold higher, respectively, than that of the initial turtles. By contrast, absolute amounts of C20:5 and C22:6 in muscle of turtles fed diet without lipid supplementation were slightly less than those in the initial turtles. For turtles fed lipid supplemented diets, tissue C20:5 and C22:6, however, increased when dietary lipid level increased. These results suggest that soft-shelled turtles are capable of synthesizing fatty acids up to 18 carbons from other nutrients and that they may have limited or no ability to synthesize highly unsaturated fatty acids. Lipid peroxidation measured by thiobarbituric acid-reactive substances in tissues of turtles fed 12% and 15% lipids was greater (p<0.05) than that in turtles fed 3% to 9% lipids. This could be due to high lipid and unsaturated fatty acid content in these tissues. On lipid basis, lipid peroxidation in turtles fed diet without lipid supplementation was the highest among all groups suggesting the existence of antioxidant factors in the dietary lipids.     

Dietary oils high in oleic acid, but with different non-glyceride contents, have different effects on lipid profiles and peroxidation in rabbit hepatic mitochondria

The influence on the lipid profile and lipid peroxidation in rabbit-liver mitochondria exerted by different edible oils high in oleic acid but different non-glyceride phenolic fractions was studied. High-phenolic virgin olive oil from the variety "Picual", the same oil submitted to an exhaustive process of washing to eliminate the phenolic fraction without altering the lipid profile and high-oleic sunflower oil (poor in phenolic compounds) were added to rabbit diets. The results reveal the importance of the different oleic: linoleic ratio of the lipid sources on the lipid profile of mitochondrial membranes. This is highlighted by the greater proportion of saturated fatty acids and the lower content in oleic acid (p < 0.05) shown by the rabbits fed on high-oleic sunflower oil. The group fed on the fat rich in phenolics exhibited the highest level of antioxidants (alpha-tocopherol, ubiquinone 10) and the highest activity of glutathione peroxidase as well as the lowest content in hydroperoxides and TBARS. The study provides evidences in vivo about the considerable antioxidant capacity of the phenolic fraction of virgin olive oil in rabbit-liver mitochondria and the important role that this non-glyceride fraction can play in the overall antioxidant benefits attributed to this oil.     

Antioxidant effect of vitamin E and glutathione on lipid peroxidation in boar semen plasma

The protective effect of vitamin E and reduced glutathione (GSH) against lipid peroxidation in boar semen plasma was studied. The lipid peroxidation, measured by the test for thiobarbituric acid reactive substances (TBARS), doubled in the presence of the lipid peroxidation Fe²⁺-sodium ascorbate-inducing system. The ascorbate-induced TBARS were inhibited by about 62% through the water-soluble vitamin E analog (TROLOX) and about 57% by GSH. In the in vivo experiments, 7 wk of oraldl-α-tocopherol acetate (1000 IU/d/animal) administration caused a significant fall in the level of the semen plasma TBARS, from 2.2±0.09 to 1.2±0.13 nmol MDA/mL. The semen plasma superoxide dismutase (SOD) and GSSG tended to increase with the time of vitamin E administration, but the increment did not reach a significant level by the seventh week. The vitamin E supplementation significantly increased the number of spermatozoa per 1 cm³ of ejaculate. The protective role of vitamin E and GSH with respect to boar semen against fatty acid peroxidation and a positive influence of vitamin E supplementation on semen quality have been evidenced.     

Ischemia/Reperfusion-induced oxidative stress causes structural changes of brain membrane proteins and lipids

Oxidative stress is a recognized factor of ischemia reperfusion injury. It shares damage of lipids (LPO) and proteins (PPO), and consequently might cause changes in activity of transport systems. Global 15 min ischemia followed by 2, 24 and 48 hour reperfusion was induced by four-vessel occlusion in Wistar rats of both sexes. Levels of TBARS and conjugated dienes as parameters of LPO were analyzed in forebrain homogenates. Concentrations of total free sulfhydryl (SH) groups and emission spectra of tryptophan were measured to quantify PPO. Our results indicate that lipid peroxidation and protein oxidation occurs mainly during the period of reperfusion. However, significant increase in the level of conjugated dienes can be detected already after 15 min ischemia. Attack of proteins by free radicals leads to modification in structure of proteins seen as a decrease of free SH groups and tryptophan fluorescence. Ischemia/reperfusion induces formation of lipid peroxidation products as well as protein modifications.     

Effect of DL-alpha-lipoic acid on the status of lipid peroxidation and antioxidants in mitochondria of aged rats

The life span of a species is thought to be determined by the rate of mitochondrial damage which in turn is inflicted by free radicals in the mitochondria during the course of normal metabolism. The level of lipid peroxidation and antioxidants were measured in liver and kidney mitochondria of young and aged rats before and after DL-alpha-lipoic acid supplementation. In both liver and kidney, mitochondrial lipid peroxidation increased with age and a decrease in the enzymatic and non-enzymatic antioxidants were observed. DL-alpha-lipoic acid treated aged rats showed a decrease in the level of lipid peroxides and an increase in the antioxidant status. Our results conclude that supplementation of lipoic acid restores the depleted mitochondrial antioxidant status and suggest that it could be an effective therapeutic agent in treatment of age-associated disorders where free radicals are the major causative factor.     

Enzyme release and mitochondrial activity in reoxygenated cardiac muscle: relationship with oxygen-induced lipid peroxidation

The aim of this work was to precisely determine the sites of the peroxidative action on unsatured lipids by oxygen-derived free radicals and the lytic cell damage on reoxygenated perfused hearts. The cellular load of lipid peroxidation products (malondialdehyde) during the reoxygenation was dependent on PO2. This unfavorable biochemical response was linked to creatine kinase leakage, alteration of coronary flow and mitochondrial injury. When an enzymatic (superoxide dismutase, 290 IU/minute) or tripeptide scavenger of oxygen radicals (reduced glutathione, 0.5 mmol/l) was administered at the end of hypoxia and during reoxygenation, the abnormal intolerance of hypoxic heart to molecular oxygen was significantly weakened; the load of lipid peroxides load, enzyme release, and vascular alteration were all reduced. Moreover, mitochondrial activity was enhanced and the oxygen-induced uncoupling of mitochondrial remained limited: both the respiratory control ratio (RCR) and the ADP/O ratio were higher than in control reoxygenated hearts. The inhibition by rotenone (100 mumol/l) of reoxidation of electron chain transfer during oxygen readmission also reduced the unfavorable cardiac accumulation of lipid peroxidation products and the release of creatine kinase. These data demonstrate that in the oxygen paradox, the peroxidative attack on lipids plays an important role in inducing alterations of sarcolemmal permeability and mitochondrial activity. An uncontrolled reactivation of oxidative function of mitochondria during reoxygenation enhances the synthesis of oxygen-derived free radicals and triggers the peroxidation of cardiac lipids resulting in irreversible injury to cellular and intracellular membranes.     

Fatty acid composition and lipid peroxidation of soft-shelled turtle, Pelodiscus sinensis, fed different dietary lipid sources

Juvenile soft-shelled turtles (Pelodiscus sinensis) were fed 7 diets containing 8% of lard, soybean oil, olive oil, menhaden fish oil, or mixtures of 1 to 1 ratio of fish oil and lard, soybean oil, olive oil for 10 weeks. Growth and muscle proximate compositions of the turtles were not affected by different dietary treatments (p>0.05). Fatty acid profiles in muscle polar lipids, muscle non-polar lipids, and liver polar lipids reflected the fatty acid composition of dietary lipid source. Turtles fed diets containing fish oil generally contained significantly higher (p<0.05) proportion of highly unsaturated fatty acids (HUFA) in both polar and non-polar lipids of muscle and polar fraction of liver lipids than those fed other oils. Non-polar fraction of liver lipids from all groups of turtles contained less than 1% of HUFA. All turtles contained relatively high proportions of oleic acid in their lipids regardless of the dietary lipid source. Further, lipid peroxidation in both muscle tissue and liver microsomes of turtles fed fish oil as the sole lipid source was greater (p<0.05) than those fed fish oil-free diets. Turtles fed olive oil as the sole lipid source had the lowest lipid peroxidation rate among all dietary groups. The results indicate that dietary n-3 HUFA may not be crucial for optimal growth of soft-shelled turtles although they may be used for metabolic purpose. Further, high level of dietary HUFA not only increases the HUFA content in turtle tissues, but also enhances the susceptibility of these tissues to lipid peroxidation.     

Lipid peroxidation induced by a novel porphyrin plus light in isolated mitochondria: Possible implications in photodynamic therapy

With a view to locate porphyrins for use in photodynamic therapy (PDT), the new modality of cancer treatment we have evaluated the ability of a novel water soluble porphyrin meso-tetrakis[4-(carboxymethyleneoxy)phenyl]porphyrin (T4CPP) to induce damage to mitochondria during photosensitization. T4CPP, when exposed to visible light, induced lipid peroxidation in rat liver mitochondria as assessed by the formation of thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD) and lipid hydroperoxides (LOOH). The effect on mitochondrial function was assessed by estimating the activity of succinate dehydrogenase (SDH). The peroxidation induced was observed to be time- and concentration- dependent. Analysis of product formation and selective inhibition by scavengers of reactive oxygen species showed that the oxidative damage observed was mainly due to singlet oxygen (1O2) and partly due to other reactive species. T4CPP plus light also caused significant lipid peroxidation in Sarcoma 180 ascites tumour mitochondria. Our studies indicate that T4CPP has the potential to photoinduce damage in hepatic and ascites mitochondria, a crucial site of damage in PDT. (Mol Cell Biochem 166: 25-33, 1997)     

Role of glutathione, lipid peroxidation and antioxidants on acute bile-duct obstruction in the rat

The aim of this work was to evaluate the role of lipid peroxidation and glutathione on liver damage induced by 7-day biliary obstruction in the rat. Male Wistar rats were bile-duct-ligated and divided in groups of 10 animals. Groups received vitamin E (400 IU/rat, p.o., daily) or trolox (50 mg/kg, p.o., daily) or both. Lipid peroxidation increased significantly in the livers of bile-duct-ligated rats. Vitamin E and trolox prevented lipid peroxidation. GSH was oxidized in the BDL group and the GSH/GSSG ratio decreased as a consequence. However, total glutathione content increased in liver and blood indicating a possible induction in de novo synthesis of GSH. Antioxidants preserved the normal GSH/GSSG ratio. Despite the observation that antioxidants verted lipid peroxidation and oxidation of GSH, liver injury (as assessed by serum enzyme activities, bilirubin concentration, liver glycogen content and histology) was not affected by the treatments. These results suggest that drugs that inhibit lipid peroxidation and oxidation of glutathione have no effect on conventional biochemical markers of liver injury and on liver histology of bile-duct-ligated rats for 7 days. It seems more likely that the detergent action of bile salts is responsible for solubilization of plasma membranes and cell death, which in turn may lead to oxidative stress, GSH oxidation and lipid peroxidation.     

The role of phospholipase A2 in microsomal lipid peroxidation induced with t-butyl hydroperoxide

The role of phospholipase A2 (PlA2) in lipid peroxidation induced with t-butyl hydroperoxide was examined in rat liver microsomes. Exposure of microsomes to t-butyl hydroperoxide was associated with activation of endogenous PlA2. When PlA2 was inhibited with chlorpromazine, mepacrine, or p-bromphenacyl bromide, the accumulation of thiobarbituric acid reactive substances (TBARS) was reduced in a dose dependent manner. In contrast, the accumulation of conjugated dienes was not affected by chlorpromazine, and was slightly increased by mepacrine. When endogenous PlA2 was activated with mellitin prior to induction of peroxidation, accumulation of both TBARS and dienes was reduced. Analogously, pretreatment with exogenous PlA2 reduced both dienes and TBARS. In contrast, addition of mellitin following the induction of peroxidation did not alter either TBARS or dienes.     

Reaction of xanthine oxidase-derived oxidants with lipid and protein of human plasma

Xanthine oxidase and purines have recently been detected in the circulation during acute viral infection and following hepatotoxicity and shock. Reactions of xanthine oxidase-generated oxidants with human plasma or bovine serum albumin (BSA) and egg phosphatidylcholine (PC) liposomes have been studied by measuring protein sulfhydryl oxidation and two markers of free radical-mediated lipid peroxidation, thiobarbituric acid reactive substances (TBARS) and conjugated dienes. Plasma incubated with 5 mU/ml xanthine oxidase (XO) and 0.5 mM hypoxanthine (Hx) for 2 h at 37 degrees C had 25-53% oxidation of sulfhydryl groups, with greater than 80% of the oxidation occurring during the first 20 min of the reaction. Concentrations of BSA similar to those present in serum, when exposed to XO/Hx-mediated oxidative stress, showed an even greater decrease in sulfhydryl concentration than that of plasma. No significant increase in plasma TBARS and conjugated dienes was observed during the 2-h incubation period in the presence of XO. Egg PC liposomes, suspended to a plasma phospholipid-equivalent concentration, showed a minor increase in TBARS and conjugated dienes under similar XO/Hx incubation conditions. In the presence of 0.23 mM BSA, lipid peroxidation was completely inhibited. A similar inhibition of lipid peroxidation was induced by cysteine but not by uric acid. Electrophoretic and arsenite-mediated sulfur reduction analysis revealed that BSA was oxidized beyond the disulfide form, with sulfenic acid formed during the initial period of oxidation. Protein sulfhydryls served as sacrificial antioxidants, preventing plasma lipid peroxidation, as well as being targets for oxidative damage. Plasma protein thiol oxidation was determined to be a more sensitive and specific indication of oxidant stress to the vascular compartment than assessment of lipid oxidation byproducts.     

Effect of clofibrate treatment on lipid peroxidation in rat liver homogenate and subcellular fractions

1. A study was made of the effect of hypolipidemic drug clofibrate on the level of lipid peroxidation in homogenates and subcellular fractions of rat liver. The intensity of lipid peroxidation was measured using chemiluminescence technique and malondialdehyde formation. 2. It was shown that under the action of clofibrate the levels of Fe/ADP-ascorbate-, as well as t-butyl hydroperoxide (Bu'OOH)-induced lipid peroxidation were decreased in the whole and "post-nuclear" liver homogenates. Dilution of the homogenates prevented depressing effect of clofibrate on lipid peroxidation. 3. Clofibrate significantly decreased the level of the Bu'OOH-dependent lipid peroxidation, but did not affect the activity of the Fe/ADP-ascorbate-induced reaction in rat liver mitochondria and microsomes. 4. Peroxidative alteration of membrane lipids in vivo was evaluated by determining the extent of conjugated dienes formation (absorption at 233 nm). It was shown that clofibrate did not increase the level of ultraviolet absorption of lipids from rat liver subcellular fractions. 5. The data obtained indicate that cytosol from the clofibrate treated rat liver contains a factor(s) which prevents lipid peroxidation in the mitochondria and microsomes.     

Fish oil and vitamin E supplementation in oxidative stress at rest and after physical exercise

Sen, Chandan K., Mustafa Atalay, Jyrki Ågren,David E. Laaksonen, Sashwati Roy, and Osmo Hänninen. Fishoil and vitamin E supplementation in oxidative stress at rest and afterphysical exercise. J. Appl. Physiol.83(1): 189-195, 1997.Fish oil supplementation and physicalexercise may induce oxidative stress. We tested the effects of 8 wk of-tocopherol (vitamin E) and fish oil (FO) supplementation on resting and exercise-induced oxidative stress. Rats(n = 80) were divided into groupssupplemented with FO, FO and vitamin E (FOVE), soy oil (SO), and SO andvitamin E (SOVE), and for FOVE and SOVE they were dividedinto corresponding exercise groups (FOVE-Ex and SOVE-Ex). Lipidperoxidation [thiobarbituric acid-reacting substances(TBARS)] was 33% higher in FO compared with SO in the liver, butoxidative protein damage (carbonyl levels) remained similar in bothliver and red gastrocnemius muscle (RG). Vitamin E supplementation,compared with FO and SO, markedly decreased liver and RG TBARS, butliver TBARS remained 32% higher in FOVE vs. SOVE. Vitamin E alsomarkedly decreased liver and RG protein carbonyl levels, althoughlevels in FOVE and SOVE were similar. Exercise increased liver and RGTBARS and RG protein carbonyl levels markedly, with similar levels inFOVE-Ex and SOVE-Ex. FO increased lipid peroxidation but not proteinoxidation in a tissue-specific manner. Vitamin E markedly decreasedlipid peroxidation and protein oxidation in both FOVE and SOVE,although liver lipid peroxidation remained higher in FOVE. Despitehigher levels of hepatic lipid peroxidation at rest in FOVE comparedwith SOVE, liver appeared to be relatively less susceptible toexercise-induced oxidative stress in FOVE.