Curcumin ameliorates oxidative stress during nicotine-induced lung toxicity in Wistar rats

Nicotine, a major toxic component of cigarette smoke has been identified as a major risk factor for lung related diseases. In the present study, we evaluated the protective effects of curcumin on lipid peroxidation and antioxidants status in bronchoalveolar lavage fluid (BALF) and bronchoalveolar lavage (BAL) of nicotine treated Wistar rats. Lung toxicity was induced by subcutaneous injection of nicotine at a dose of 2.5 mg/kg body weight (5 days a week, for 22 weeks) and curcumin (80 mg/kg body weight) was given simultaneously by intragastric intubation for 22 weeks. Measurement of biochemical marker enzymes: alkaline phosphatase, lactate dehydrogenase, lipid peroxidation and antioxidants were used to monitor the antiperoxidative effects of curcumin. The increased biochemical marker enzymes as well as lipid peroxides in BALF and BAL of nicotine treated rats was accompanied by a significant decrease in the levels of glutathione, glutathione peroxidase, superoxide dismutase and catalase. Administration of curcumin significantly lowered the biochemical marker enzymes, lipid peroxidation and enhanced the antioxidant status. The results of the present study suggest that curcumin exert its protective effect against nicotine-induced lung toxicity by modulating the biochemical marker enzymes, lipid peroxidation and augmenting antioxidant defense system.     

Pulmonary protective effects of curcumin against paraquat toxicity

An early feature of paraquat (PQ) toxicity is the influx of inflammatory cells, releasing proteolytic enzymes and oxygen free radicals, which can destroy the lung epithelium and result in pulmonary fibrosis. Therefore, the ability to suppress early lung injury seems to be an appropriate therapy of pulmonary damage before the development of irreversible fibrosis. Here I show curcumin confers remarkable protection against PQ lung injury. A single intraperitoneal injection of PQ (50 mg/kg) resulted in a significant rise in the levels of protein, angiotensin converting enzyme (ACE), alkaline phosphatase (AKP), N-acetyl-beta-D-glucosaminidase (NAG) and thiobarbituric acid reactive substances (TBARS), and neutrophils in the bronchoalveolar lavage fluid (BALF), while a decrease in glutathione levels. In paraquat rats bronchoalveolar lavage (BAL) cell TBARS concentration was increased with a simultaneous decrease in glutathione content. In addition, the data also demonstrated that PQ caused a decrease in ACE and glutathione levels and an increase in levels of TBARS and myeloperoxidase (MPO) activity in the lung. Interestingly, curcumin prevented the general toxicity and mortality induced by PQ and blocked the rise in BALF protein, ACE, AKP, NAG TBARS and neutrophils. Similarly, curcumin prevented the rise in TBARS content in both BAL cell and lung tissue and MPO activity of the lung. In addition, PQ induced reduction in lung ACE and BAL cell and lung glutathione levels was abolished by curcumin treatment. These findings indicate that curcumin has important therapeutic implications in facilitating the early suppression of PQ lung injury.     

Elevated semicarbazide-sensitive amine oxidase (SSAO) activity in lung with ischemia-reperfusion injury: protective effect of ischemic preconditioning plus SSAO inhibition

Ischemic preconditioning (IP) has been shown to protect the lung against ischemia-reperfusion (I/R) injury. Although the production of reactive oxygen species (ROS) has been postulated to play a crucial role in I/R injury, the sources of these radicals in I/R and the mechanisms of protection in IP remain unknown. Since it was postulated that deamination of endogenous and exogenous amines by semicarbazide-sensitive amine oxidase (SSAO) in tissue damage leads to the overproduction of hydrogen peroxide (H2O2), we investigated the possible contribution of tissue SSAO to excess ROS generation and lipid peroxidation during I/R and IP of the lung. Male Wistar rats were randomized into 6 groups: control lungs were subjected to 30 min of perfusion in absence and presence of SSAO inhibitor, whereas the lungs of the I/R group were subjected to 2 h of cold ischemia following the 30 min of perfusion in absence and presence of SSAO inhibitor. IP was performed by two cycles of 5 min ischemia followed by 5 min of reperfusion prior to 2 h of hypothermic ischemia in absence and presence of SSAO inhibitor. Lipid peroxidation, reduced (GSH) and oxidized (GSSG) glutathione levels, antioxidant enzyme activities, SSAO activity, and H2O2 release were determined in tissue samples of the study groups. Lipid peroxidation, glutathione disulfide (GSSG) content, SSAO activity and H2O2 release were increased in the I/R group, whereas GSH content, GSH/GSSG ratio and antioxidant enzyme activities were decreased. SSAO activity, H2O2 release, GSSG content and lipid peroxidation were markedly decreased in the IP group, whereas GSH content, GSH/GSSG ratio and antioxidant enzyme activities were significantly increased. SSAO activity was found to be positively correlated with H2O2 production in all study groups. Increased lipid peroxidation, SSAO activity, GSSG and H2O2 contents as well as decreased GSH and antioxidant enzyme levels in I/R returned to their basal levels when IP and SSAO inhibition were applied together. The present study suggests that application of IP and SSAO inhibition together may be more effective than IP alone against I/R injury in the lung.     

Synergistic interactions of Ferulic acid with Ascorbic acid: Its cardioprotective role during isoproterenol induced myocardial infarction in rats

Studies on the lipid peroxidation and antioxidant changes and their significance during myocardial injury have provided a new insight into the pathogenesis of heart disease. The heart failure subsequent to myocardial infarction may be associated with an antioxidant deficit as well as increased myocardial oxidative stress. The present study was designed to evaluate the effect of the combination of ferulic acid and ascorbic acid on antioxidant defense system and lipid peroxidation against isoproterenol (ISO)-induced myocardial infarction in rats. Induction of rats with isoproterenol (150 mg/kg body weight daily, i.p.) for 2 days resulted in a marked elevation in lipid peroxidation, serum marker enzymes (LDH, CPK, GOT, and GPT), and a significant decrease in activities of endogenous antioxidants (SOD, GPx, GST, CAT, and GSH). Pre-co-treatment with the combination of ferulic acid (20 mg/kg body weight/day) and ascorbic acid (80 mg/kg body weight/day) orally for 6 days, significantly attenuated these changes when compared to the individual treatment groups. Histopathological observations were also in correlation with the biochemical parameters. Thus, ferulic acid and ascorbic acid significantly counteracted the pronounced oxidative stress effect of ISO by the inhibition of lipid peroxidation, restoration of antioxidant status, and myocardial marker enzymes levels. In conclusion, these findings indicate the synergistic protective effect of ferulic acid and ascorbic acid on lipid peroxidation and antioxidant defense system during ISO-induced myocardial infarction and associated oxidative stress in rats.     

Gastroprotective and Anti-oxidative Properties of Ascorbic Acid on Indomethacin-induced Gastric Injuries in Rats

Reactive oxygen species (ROS) have been implicated in the etiology of indomethacin-induced gastric mucosal damage. This study investigated ascorbic acid (vitamin C)'s protective effects against oxidative gastric mucosal damage induced by indomethacin. Ascorbic acid is a powerful antioxidant because it can donate a hydrogen atom and form a relatively stable ascorbyl free radical. We have investigated alterations in the levels of myeloperoxidase, antioxidant system enzymes (glutathione S-transferase, superoxide dismutase, glutathione reductase, catalase, glutathione peroxidase), lipid peroxidation and glutathione, as markers for ulceration process following oral administration of ascorbic acid, famotidine, lansoprazole, and ranitidine in rats with indomethacin-induced ulcers. In the present study, we found that (1) ascorbic acid, famotidine, lansoprazole and ranitidine reduced the development of indomethacin-induced gastric damages; (2) the administration of indomethacin caused a significant decrease in the levels of superoxide dismutase, glutathione peroxidase, glutathione S-transferase and glutathione, and an increase in the lipid peroxidation level; (3) the administration of ascorbic acid reversed the trend, inducing a significant increase of these enzymes' levels and a reduction in lipid peroxidation level in tissues; and (4) catalase, glutathione reductase and myeloperoxidase activities, increased by indomethacin, were found to be lower in the ascorbic acid, famotidine, lansoprazole and ranitidine-treated groups. The results indicate that the gastroprotective properties of ascorbic acid could be related to its positive effects on the antioxidant system and myeloperoxidase activity in indomethacin-induced gastric ulcers in rats.     

AT1 Receptor Blocker Candesartan-induced Attenuation of Brain Injury of Rats Subjected to Chronic Cerebral Hypoperfusion

One of common pathophysiological states associated with central nervous system is chronic cerebral hypoperfusion (CH) that frequently occurs in conditions such as vascular dementia and Alzheimer’s disease. Long term blockage of angiotensin II type 1 (AT₁) receptor provides protection from ischemia induced injury of brain as well as reduction of cerebrovascular inflammation. Examining effect of the blockage on reduced glutathione (GSH), ascorbic acid (AA), and lipid peroxidation were of purpose in the present study. Modeling CH, rats were subjected to permanent occlusion of common carotid arteries bilaterally. AT₁ receptor antagonist, candesartan, was given daily for 14 days after surgery. CH caused a significant increase in lipid peroxidation and decrease in GSH content of cerebral hippocampal tissue with no change in AA level. Candesartan (0.5 mg/kg, oral) not only reduced lipid peroxidation but also restored GSH significantly besides elevating AA and improving histopathological alterations. In conclusion, long term AT₁ receptor blockage may be considered as novel therapeutic approach for protection from damage associated with CH. Underlying mechanism(s) may in part be related to suppressing oxidative stress and preserving brain antioxidant capacity.     

Bacopa monniera Linn. extract modulates antioxidant and marker enzyme status in fibrosarcoma bearing rats

Antioxidative property and tumor inhibitive property of B. monniera (20mg/kg body wt, sc) was examined in 3-methylcholanthrene induced fibrosarcoma rats. Antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and the levels of glutathione (GSH) and the rate of lipid peroxidation (LPO) in the liver and kidney tissues were assessed. A significant increase was noted for the rate of LPO with a corresponding decrease in the antioxidant enzyme status in fibrosarcoma bearing rats. In fibrosarcoma bearing rats, the tumor markers like lactate dehydrogenase (LDH), creatine kinase (CK), alanine transaminase (ALT), aspartate transaminase (AST) and sialic acid (SA) were increased in the serum. Treatment with B. monniera extract significantly increased the antioxidant enzyme status, inhibited lipid peroxidation and reduced the tumor markers. It can be concluded that B.monniera extract promotes the antioxidant status, reduces the rate of lipid peroxidation and the markers of tumor progression in the fibrosarcoma bearing rats.     

Oxidative Stress in Cerebrospinal Fluid of Patients with Aseptic and Bacterial Meningitis

This study aimed to determine whether patients with aseptic and bacterial meningitis presented alterations in oxidative stress parameters of cerebrospinal fluid (CSF). A total of 30 patients were used in the research. The CSF oxidative stress status has been evaluated through many parameters, such as lipid peroxidation through thiobarbituric acid reactive substances (TBARS) and antioxidant defense systems such as superoxide dismutase (SOD), glutathione S-transferase (GST), reduced glutathione (GSH) and ascorbic acid. TBARS levels, SOD and GST activity increase in aseptic meningitis and in bacterial meningitis. The ascorbic acid concentration increased significantly in patients with both meningitis types. The reduced glutathione levels were reduced in CSF of patients with aseptic and bacterial meningitis. In present study we may conclude that oxidative stress contributes at least in part to the severe neurological dysfunction found in meningitis.     

Protective Effects of Curcumin against Sodium Fluoride-Induced Toxicity in Rat Kidneys

In the present study, the protective effect of curcumin against sodium fluoride-induced nephrotoxicity was evaluated in rats. Renal injury was induced by daily administration of 600 ppm sodium fluoride in drinking water for 1 week. One week before the administration of fluoride, the animals selected as study group were given curcumin (10 and 20 mg/kg body weight, intraperitoneally). After 1 week, lipid peroxidation level, activities of superoxide dismutase, catalase, and level of glutathione in kidney homogenate were measured. Blood serum samples were examined for creatinine, serum urea, and blood urea nitrogen levels. Another group of rats received vitamin C (10 mg/kg) as standard antioxidant. The results show that curcumin and vitamin C treatment prior to fluoride administration normalized the levels of serum creatinine, serum urea, and blood urea nitrogen. Moreover, curcumin and vitamin C administrations prevented the antioxidant enzyme decreasing and lipid peroxidation levels imbalance. In conclusion, curcumin treatment at the doses of 10 and 20 mg/kg (intraperitoneally) showed significant nephroprotective effects.     

Ischemia-reperfusion leads to depletion of glutathione content and augmentation of malondialdehyde production in the rat heart from overproduction of oxidants: Can caffeic acid phenethyl ester (CAPE) protect the heart?

During restoration of blood flow of the ischemic heart induced by coronary occlusion, free radicals cause lipid peroxidation with myocardial injury. Lipid peroxidation end-products, such as malondialdehyde (MDA), have been used to assess oxygen free radical-mediated injury of the ischemic-reperfused (I/R) myocardium in rats. This experimental study assessed the preventive effect of caffeic acid phenthyl ester (CAPE), antioxidant, on I/R-induced lipid peroxidation in the rat heart. We are also interested in the role of CAPE on glutathione (GSH) levels, an antioxidant whose levels are influenced by oxidative stress. I/R leads to the depletion of GSH which is the major intracellular nonprotein sulphydryl and plays an important role in the maintenance of cellular proteins and lipid in their functional state and acts primarily to protect these important structures against the threat of oxidation. In addition, we also examined morphologic changes in the heart by using light microscopy. The left coronary artery was occluded for 30 min and then reperfused for 120 min more before the experiment was terminated. CAPE (50 M kg^–1) was administered 10 min prior to ischemia and during occlusion by infusion. At the end of the reperfusion period, rats were sacrificed, and the heart was quickly removed for biochemical determination and histopathological analysis. I/R was accompanied by a significant increase in MDA production and decrease in GSH content in the rat heart. Administration of CAPE reduced MDA production and prevented depletion of GSH content. These beneficial changes in these biochemical parameters were also associated with parallel changes in histopathological appearance. These findings imply that I/R plays a causal role in heart injury due to overproduction of oxygen radicals or insufficient antioxidant and CAPE exert cardioprotective effects probably by the radical scavenging and antioxidant activities.     

Stimulation of thiamine diphosphatase activity by ascorbic acid in rat brain microsomes.

The effect of ascorbic acid on microsomal thiamine diphosphatase activity in rat brain was examined. Ascorbic acid at 0.02--0.1 mM increased the thiamine diphosphatase activity by 20--600% and produced a significant amount of lipid peroxide, which was measured with thiobarbiturate under the same conditions as the enzyme. A lag period of about 10 min was observed in the process of stimulation of enzyme activity by ascorbic acid. The stimulation of enzyme activity and the lipid peroxidation induced by ascorbic acid were blocked by metal-binding compounds (EDTA, alpha,alpha'-dipyridyl, o-phenanthroline) and an antioxidant (N,N'-diphenyl p-phenylenediamine). GSH significantly enhanced the stimulation of enzyme activity and formation of lipid peroxide by 0.02--0.05 mM ascorbic acid. The effect of GSH was due in part to maintenance of the concentration of ascorbic acid in the medium, since GSH could convert dehydroascorbic acid, an oxidized form of ascorbic acid, to ascorbic acid.     

Influence of dietary ginger (Zingiber officinales Rosc) on antioxidant defense system in rat: comparison with ascorbic acid

Ginger (Z. officinale; 1% w/w) significantly lowered lipid peroxidation by maintaining the activities of the antioxidant enzymes--superoxide dismutase, catalase and glutathione peroxidase in rats. The blood glutathione content was significantly increased in ginger fed rats. Similar effects were also observed after natural antioxidant ascorbic acid (100 mg/kg, body wt) treatment. The results indicate that ginger is comparatively as effective as ascorbic acid as an antioxidant.     

Protective role of curcumin against isoproterenol induced myocardial infarction in rats

The effect of curcumin on the biochemical changes induced by isoproterenol (ISO) administration in rats was examined. ISO (300 mg Kg^–1 administered subcutaneously twice at an interval of 24 h) caused a decrease in body weight and an increase in heart weight, water content as well as in the levels of serum marker enzymes viz creatine kinase (CK), lactate dehydrogenase (LDH) and LDH₁ isozyme. It also produced electrocardiographic changes such as increased heart rate, reduced R amplitude and ST elevation. Curcumin at a concentration of 200 mg.Kg^–1 when administered orally, showed a decrease in serum enzyme levels and the electrocardiographic changes got restored towards normalcy. Myocardial infarction was accompanied by the disintegration of membrane polyunsaturated fatty acids expressed by increase of thiobarbituric acid reactive substance (TBARS), a measure of lipid peroxides and by the impairment of natural scavenging, characterized by the decrease in the levels of superoxide dismutase, catalase, glutathione peroxidase, ceruloplasmin, alpha tocopherol, reduced glutathione (GSH) and ascorbic acid. The oral pretreatment with curcumin two days before and during ISO administration decreased the effect of lipid peroxidation. It was shown to have a membrane stabilizing action by inhibiting the release of -glucuronidase from nuclei, mitochondria, lysosome and microsome. Curcumin pre- and co-treatment decreased the severity of pathological changes and thus, could have a protective effect against the damage caused by myocardial infarction (MI).     

Effect of nicotinamide on the reactions of peroxide oxidation of biomolecules in the rat brain and erythrocytes in 1,2-dichloroethane toxic injury

It was established that acute poisoning of rats by 1,2-dichloroethane induced considerable changes in lipid peroxidation indices, glutathione content and activity of antioxidant enzymes--superoxidase, catalase, glutathione peroxidase in the brain tissue, erythrocytes and blood plasma. It was shown that nicotinamide in the dose of 200 mg/kg prevented considerable degree of the intoxication caused by 1,2-dichloroethane as well as activation of lipid peroxidation and inhibition of antioxidant defens enzyme activities in tissue of experimental animals.     

Stimulation of thiamine diphosphate activity by ascorbic acid in rat brain microsomes

The effect of ascorbic acid on microsomal thiamine diphosphate activity in rat brain was examined. Ascorbic acid at 0.02–0.1 mM increased the thiamine diphosphate activity by 20–600% and produced a significant amount of lipid peroxide, which was measured with thiobarbiturate under the same conditions as the enzyme. A lag period of about 10 min was observed in the process of stimulation of enzyme activity by ascorbic acid. The stimulation of enzyme activity and the lipid peroxidation induced by ascorbic acid were blocked by metal-binding compounds (EDTA, α,α′-dipyridyl, o-phenanthroline) and an antioxidant (N,N′-diphenyl p-phenylenediamine). GSH significantly enhanced the stimulation of enzyme activity and formation of lipid peroxide by 0.02–0.05 mM ascorbic acid. The effect of GSH was due in part to maintenance of the concentration of ascorbic acid in the medium, since GSH could convert dehydroascorbic acid, an oxidized form of ascorbic acid, to ascorbic acid.     

Modulation of endoperoxide product levels and cyclophosphamide-induced injury by glutathione repletion

Glutathione is a tripeptide important in a number of diverse cellular functions including enzymatic reactions involved in prostaglandin endoperoxide metabolism. We have previously reported that cyclophosphamide administration to rats results in acute lung injury manifested by increased bronchoalveolar lavage albumin concentrations. In the current study we examine whether cyclophosphamide treatment affects pulmonary glutathione stores or bronchoalveolar endoperoxide metabolic product levels and whether these effects may be related to acute lung injury caused by the drug. We show that cyclophosphamide treatment causes a dose-dependent reduction in pulmonary glutathione stores 4 h after drug administration. In addition, acute lung injury as the result of cyclophosphamide can be abrogated by coadministration of oxothiazolidine carboxylate, an intracellular cysteine delivery system that also reverses pulmonary glutathione depletion induced by cyclophosphamide in our study. Finally, cyclophosphamide treatment reduces prostaglandin E2 concentrations in bronchoalveolar lavage and alveolar macrophage culture supernatant in a dose-dependent fashion and increases bronchoalveolar thromboxane concentrations in low dose-treated animals. These effects are reversed to a variable degree by coadministration of oxothiazolidine carboxylate. Our study suggests in vivo pulmonary arachidonic acid metabolism and cyclophosphamide-induced acute lung injury are modulated by cellular glutathione stores. These findings may have important implications for the treatment of acute lung injury.     

Effect of citrate feeding on free radical induced changes in experimental urolithiasis.

Feeding calculi producing diet (CPD) to rats for 4 weeks produced calcium oxaltate stones. Supplementation of sodium citrate to CPD (c-CPD) prevented stone formation. Except oxalate, the excretion of calcium, phosphorus and magnesium was restored to normal in c-CPD fed rats. The CPD fed rats exhibited increase in glycolic acid oxidase (GAO) and lactate dehydrogenase (LDH) activities and only GAO activity was partially restored in c-CPD fed rats. Kidney sub-cellular fractions of calculi producing diet (CPD) fed rats showed increased susceptibility for lipid peroxidation in presence of promotors. Antioxidant enzyme activities of superoxide dismutase (SOD), catalase and glutathione peroxidase and antioxidant concentrations of reduced glutathione, total thiols, ascorbic acid and vitamin E were significantly decreased while the xanthine oxidase activity, and concentrations of hydroxyl radical, diene conjugates and hydroperoxides were significantly increased in CPD fed rats. The susceptibility to lipid peroxidation, activities of antioxidant enzymes, and the concentration of antioxidants were not normalized by feeding citrate.     

Taurine restores ethanol-induced depletion of antioxidants and attenuates oxidative stress in rat tissues

Summary. Ethanol by its property of generating free radicals during the course of its metabolism causes damage to cell structure and function. The study investigates the protective effects of the antioxidant aminoacid taurine on ethanol-induced lipid peroxidation and antioxidant status. Male Wistar rats of body weight 170–190g were divided into 4 groups and maintained for 28 days as follows: a control group and taurine-supplemented control group, taurine supplemented and unsupplemented ethanol-fed group. Ethanol was administered to rats at a dosage of 3g/kg body weight twice daily and taurine was provided in the diet (10g/kg diet). Lipid peroxidation products and antioxidant potential were quantitated in plasma and in following tissues liver, brain, kidney and heart.Increased levels of thiobarbituric acid substances (TBARS) and lipid hydroperoxides (LHP) in plasma and tissues, decreased activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were observed in hemolysate and tissues of ethanol-fed rats. The contents of reduced glutathione (GSH), -tocopherol and ascorbic acid in plasma and tissues were significantly reduced in these animals as compared to control animals. Simultaneous administration of taurine along with ethanol attenuated the lipid peroxidation process and restored the levels of enzymatic and non-enzymatic antioxidants. We propose that taurine may have a bioprotective effect on ethanol-induced oxidative stress.     

Concentration dependent antioxidant/pro-oxidant activity of curcumin studies from AAPH induced hemolysis of RBCs

The antioxidant properties of curcumin have been studied by evaluating its ability to protect RBCs from AAPH (2,2'-azobis (2-amidinopropane) hydrochloride) induced oxidative damage. RBCs are susceptible to oxidative damage, resulting in peroxidation of the membrane lipids, release of hemoglobin (hemolysis), release of intracellular K(+) ions and depletion of glutathione (GSH). In this paper, lipid peroxidation, hemolysis and K(+) ion loss in RBCs were assessed respectively by formation of thiobarbituric acid reactive substances (TBARS), absorbance of hemoglobin at 532nm and flame photometry. The treatment of RBCs with curcumin showed concentration dependant decrease in level of TBARS and hemolysis. The IC(50) values for inhibition of lipid peroxidation and hemolysis were estimated to be 23.2+/-2.5 and 43+/-5microM respectively. However in contrast to the above mentioned effects, curcumin in similar concentration range, did not prevent release of intracellular K(+) ions during the process of hemolysis, rather curcumin induced its release even in the absence of hemolysis. The ability of curcumin to prevent oxidation of intracellular GSH due to hemolysis showed mixed results. At low concentrations of curcumin (<10microM) it prevented GSH depletion and at higher concentrations, the GSH levels decreased gradually. Curcumin scavenges the peroxyl radical generated from AAPH. Based on these results, it is concluded that curcumin exhibits both antioxidant/pro-oxidant activity, in a concentration dependent manner.     

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.