Protective effect of vitamin E on chromium (VI)-induced cytotoxicity and lipid peroxidation in primary cultures of rat Hepatocytes

Pretreatment of primary cultures of rat hepatocytes with α-tocopherol succinate (vitamin E) for 20 h prior to exposure to K₂Cr₂O₇ resulted in a marked decrease of chromium (VI)-induced cytotoxicity, as evaluated by the leakage of lactate dehydrogenase, without affecting cellular uptake and subcellular distribution of chromium. The levels of chromium (VI)-induced lipid peroxidation, as monitored by malondialdehyde formation, were also inhibited by pretreatment with the vitamin. Pretreatment with vitamin E normalized the levels of nonenzymatic antioxidants such as glutathione and vitamin C suppressed by dichromate, and caused a distinct accumulation of vitamin E in hepatocytes. However, vitamin E pretreatment did not affect the activities of enzymatic antioxidants including glutathione reductase, superoxide dismutase, and catalase suppressed by dichromate. These results indicate that the protective effect of vitamin E against chromium (VI)-induced cytotoxicity as well as lipid peroxidation, may be associated more with the level of nonenzymatic antioxidants than the activity of enzymatic antioxidants. Received: 31 October 1995/Accepted: 16 July 1996     

Antioxidant status and lipid peroxidation in colorectal cancer

Colon carcinogenesis is a multistep process where oxygen radicals were found to enhance carcinogenesis at all stages: initiation, promotion, and progression. Since insufficient capacity of protective antioxidant system can result in cancer, the aim of this study was to examine the activity of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase) and the levels of reduced glutathione, vitamin C, and vitamin E. The lipid peroxidation products were also determined by measuring malondialdehyde and 4-hydroxynonenal levels in colorectal cancer tissue collected from 55 patients. In these cases the activity of superoxide dismutase, glutathione peroxidase, and glutathione reductase was significantly increased while the activity of catalase was significantly decreased in cancer tissue. However, the level of nonenzymatic antioxidant parameters (glutathione, vitamin C, and vitamin E) was significantly decreased in cancer tissue. Further lipid peroxidation was enhanced during cancer development, manifested by a significant increase in malondialdehyde and 4-hydroxynonenal levels. The obtained results indicate significant changes in antioxidant capacity of colorectal cancer tissues, which lead to enhanced action of oxygen radicals, resulting in lipid peroxidation.     

Failure of inhibition of lipid peroxidation by vitamin E to protect against gentamicin nephrotoxicity in the rat

We tested the hypothesis that accelerated lipid peroxidation, possibly at the level of the lysosome, is linked causally to the pathogenesis of aminoglycoside nephrotoxicity by investigating whether administration of vitamin E would inhibit lipid peroxidation and prevent or ameliorate gentamicin-induced proximal tubular cell injury. Five groups of rats were injected with either saline, vitamin E (600 mg/kg per day) for 6 days, gentamicin (100 mg/kg per day) for 6 days, vitamin E for 6 days plus gentamicin for 6 days or vitamin E for 12 days and gentamicin for the last 6 days. Gentamicin alone induced a 16% increase in renal cortical phospholipids; vitamin E had no significant effect on this change. Gentamicin alone caused accelerated lipid peroxidation evident by a doubling of renal cortical malondialdehyde to 1.23 nmol/mg protein, and a sharp decline of esterified polyunsaturated fatty acids, especially arachidonic acid which fell 43%. These changes were accompanied by depressions of superoxide dismutase, catalase, and total glutathione and a shift from reduced to oxidized glutathione. Concurrent treatment of rats with vitamin E plus gentamicin for 6 days had no significant effect on the gentamicin-induced alterations of malondialdehyde, superoxide dismutase, catalase or the glutathione cascade; however, the shift from polyunsaturated to saturated fatty acids was largely reversed. In rats pretreated with vitamin E for 6 days, gentamicin failed to raise renal cortical malondialdehyde above that of saline-treated rats. The changes in esterified fatty acids were prevented almost entirely, and there were no significant alterations from control of the glutathione cascade. The depressions of superoxide dismutase and of catalase, however, were not reversed. Vitamin E did not affect the amount of gentamicin accumulated in renal cortex nor did it prevent the gentamicin-induced rise of serum creatinine. Examination of renal cortex by light and electron microscopy revealed that vitamin E did not prevent or even reduce the severity of gentamicin-induced proximal tubular cell lesions and necrosis. These results confirm those we obtained in a previous study with the antioxidant diphenyl-phenylenediamine. The observation that inhibition of lipid peroxidation by two distinct antioxidants failed to prevent proximal tubular cell injury and renal dysfunction associated with gentamicin administration leads us to conclude that lipid peroxidation is a consequence and not a cause of gentamicin-induced nephrotoxicity.     

Status of lipid peroxidation, glutathione, ascorbic acid, vitamin E and antioxidant enzymes in patients with pregnancy--induced hypertension

The exact pro-oxidant and antioxidant status in pregnancy--induced hypertension patients is still not clear. To add a new insight to the question, changes in the erythrocyte lipid peroxidation products (malondialdehyde; MDA), levels of glutathione (GSH), ascorbic acid and plasma vitamin E (non enzymatic antioxidant parameters) and activities of antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase in erythrocytes were studied in thirty five patients with pregnancy--induced hypertension and thirty five healthy pregnant normotensive cases. It was observed that there was a significant increase in erythrocyte MDA levels, activities of SOD, GPx and a significant decrease in erythrocyte GSH, ascorbic acid, plasma vitamin E levels and catalase activity in patients with pregnancy--induced hypertension when compared to controls. The results of our study have shown higher oxygen free radical production, evidenced by increased levels of MDA and decreased levels of GSH, ascorbic acid, vitamin E and Catalase activity supports the oxidative stress in pregnancy--induced hypertension. The increased activities of antioxidant enzymes may be a compensatory regulation in response to increased oxidative stress. The decreased concentrations of glutathione and antioxidant vitamin status supports the hypothesis that lipid peroxidation is an important causative factor in the pathogenesis of preeclampsia.     

Studies of the blood lipid peroxide status and vitamin E levels in patients with chronic active hepatitis and alcoholic liver disease

As free radicals and lipid peroxidation are involved in the pathogenesis of different inflammatory diseases of the liver, the blood malondialdehyde content, the activity or quantity of free radical eliminating enzymes and the natural antioxidant, vitamin E serum level has been studied in ten patients with chronic active hepatitis and in six subjects with alcoholic liver disease. Thirty healthy volunteers served as controls. The serum malondialdehyde/thiobarbituric acid reactive substance and its concentrations increased significantly in both hepatitis groups. The superoxide dismutase content was also raised in the patients' sera. The serum glutathione peroxidase (GSH-Px) activity was decreased in both groups, while the red blood cell GSH-Px showed a significantly lower activity in the alcoholic hepatitis patients. Serum catalase activity and vitamin E levels in both types of chronic hepatitis were not significantly different from the healthy controls.     

Effects of cianidanol on the blood lipid peroxide status in patients with chronic hepatitis

This study was designed to investigate the effect of the natural bioflavonoid compound cianidanol on the blood lipid peroxide status of patients with chronic hepatitis. Nine patients had chronic active liver disease--seven of them hepatitis B virus-positive--and five had chronic alcoholic hepatitis. Besides some biochemical liver function tests (serum bilirubin, aminotransferases and gamma-glutamyl transferase), the changes in the serum level of malondialdehyde (a thiobarbituric acid reactive substance) as one of the end-products of lipid peroxidation, as well as the quantity/or activity of enzymes controlling peroxidation (superoxide dismutase (SOD), glutathione peroxidase and catalase) were measured. In addition, the serum level of the natural antioxidant vitamin E was followed-up. Cianidanol treatment (at a dose of 3.0 g/day for one month and of 1.5 g/day for two months) resulted in a slight improvement in aminotransferases and a significant fall (normalization) of high serum malondialdehyde level. After a marked transient increase, serum SOD content decreased while glutathione peroxidase and catalase activities as well as the vitamin E blood level increased during the treatment. Results suggest that (cianidanol in vivo inhibits lipid peroxidation and influences antioxidant enzyme systems and vitamin E in the blood of patients with chronic hepatitis.     

Protective effect of deferoxamine on chromium(VI)-induced DNA single-strand breaks, cytotoxicity, and lipid peroxidation in primary cultures of rat hepatocytes

Incubation of primary cultures of rat hepatocytes with K₂Cr₂O₇ and deferoxamine (DFO), an iron chelator, resulted in a marked decrease in cellular levels of DNA single-strand breaks caused by K₂Cr₂O₇. Cellular treatment with DFO also suppressed both dichromate-induced cytotoxicity – evaluated by the leakage of lactate dehydrogenase, and lipid peroxidation – as monitored by malondialdehyde formation. In addition, treatment with DFO attenuated the suppression of the levels of vitamin E and C as well as the inhibition of alkaline phosphatase and glutathione peroxidase activity attributed to K₂Cr₂O₇. However, DFO had no influence on the cellular level of glutathione or the activity of glutathione reductase and superoxide dismutase suppressed by dichromate. Under the same experimental conditions, cellular uptake and distribution of chromium were not affected by DFO. These results indicate that DFO protects cells from chromium(VI)-induced DNA strand breaks, cytotoxicity, lipid peroxidation, vitamin E and C depression, and glutathione peroxidase inhibition. The role of antioxidants in chromium(VI)-induced cytotoxicity, DNA breaks, and lipid peroxidation is discussed. Received: 17 September 1996 / Accepted: 25 November 1996     

Topiramate and vitamin e modulate antioxidant enzyme activities, nitric oxide and lipid peroxidation levels in pentylenetetrazol-induced nephrotoxicity in rats

Previous studies have shown that generation of free radicals is increased following pentylenetetrazol kindling, due to increased cytosolic Ca2+ concentrations. Topiramate, a voltage-gated calcium channel inhibitor, has an evident effect in the treatment of childhood epilepsy; however, topiramate may cause nephrotoxicity. We investigated the effects of topiramate and vitamin E administration on pentylenetetrazol-induced nephrotoxicity in rats by evaluation of lipid peroxidation, nitric oxide, glutathione peroxidase, catalase and superoxide dismutase values. Forty male Wistar rats were randomly divided into five equal groups. Group 1 was used as control and group II received a single dose of pentylenetetrazol. Fifty and 100 mg/kg topiramate daily were intragastrically administered to rats in groups III and IV for 7 days, respectively. Intragastric 100 mg topiramate (daily for 7 days) and intraperitoneal vitamin E (150 mg/kg, daily for 3 days) combination were given to animals in group V before a single-dose pentylenetetrazol administration. Serum and kidney samples were taken after 3 hr of pentylenetetrazol administration. Pentylenetetrazol resulted in a significant increase in nitric oxide levels of serum and kidney, and lipid peroxidation levels of kidney although superoxide dismutase and catalase activities in the kidney was reduced by pentylenetetrazol administration. The lipid peroxidation levels in serum and kidneys and the nitric oxide levels in kidneys of groups III, IV and V were decreased by topiramate although the superoxide dismutase and catalase activities in the kidneys were increased. Lipid peroxidation and nitric oxide levels were reduced by the topiramate and vitamin E combination compared to only topiramate. Glutathione peroxidase activity was not affect by pentylenetetrazol, topiramate and vitamin E administrations. In conclusion, topiramate and vitamin E have protective effects on pentylenetetrazol-induced nephrotoxicity by inhibition of free radicals and by support of the antioxidant redox system.     

Antioxidant Defense System Induced by a Methanol Extract of Caesalpinia bonducella. in Rat Liver

ABSTRACT

The antioxidant defense system dramatically controls hepatocellular carcinoma induced by N.-nitrosodiethylamine (NDEA). In order to assess the anticarcinogenic activity of a methanol extract of Caesalpinia bonducella. (MECB) leaves containing flavonoids and triterpenoids, the antioxidant defense system has been evaluated. The effect of MECB on lipid peroxidation end-product malondialdehyde (MDA), enzymatic antioxidants such as superoxide dismutase (SOD) and catalase (CAT), and nonenzymatic antioxidants glutathione (GSH), vitamin E, and vitamin C levels were analyzed in the liver of control and experimental animals. Serum was also analyzed for transaminase activity (SGOT and SGPT), alkaline phosphatase (SALP), bilirubin, total protein, and uric acid. Depletion of all these antioxidants was recorded in cancer conditions. These deleterious effects are controlled by the administration of MECB. After drug administration, there was a marked increase in antioxidant levels and a dramatic decrease in lipid peroxidation levels. MECB also produced a protective effect by decreasing the activity of serum enzymes, bilirubin, and increased the protein and uric acid levels. From the above results, it can be concluded that the observed anticarcinogenic properties of MECB may also be explained by its strong antioxidant capacity and capability to induce an in vivo. antioxidant system.     

Nitrofurantoin-Induced Hepatic and Pulmonary Biochemical Changes in Mice Fed Different Vitamin E Doses

Abstract: The hepatic and pulmonary effects of nitrofurantoin (40 mg/kg, intraperitoneally) were determined at 4 and 24 hr following its administration in mice fed for 10 weeks with a vitamin E sufficient, deficient or enriched diet. Liver glutathione (GSH) was reduced by nitrofurantoin at 4 hr but was unchanged 20 hr later. Nitrofurantoin did not affect liver glutathione peroxidase, glutathione reductase or superoxide dismutase activities. Liver catalase activities were decreased by nitrofurantoin at 4 hr. Lung GSH levels were increased whilst glutathione peroxidase activity was decreased at 4 and 24 hr. Lung glutathione reductase activity was reduced in certain groups. Nitrofurantoin did not affect lung superoxide dismutase, but catalase was decreased at 24 hr. Liver malondialdehyde levels were increased by nitrofurantoin in the vitamin E deficient group whilst lung malondialdehyde levels remained unchanged. Both liver and lung malondialdehyde levels were unaffected by vitamin E supplementation when compared to the vitamin E-sufficient group. These results suggest that nitrofurantoin (40 mg/kg) was deleterious to the liver and lung. Nitrofurantoin-induced lipid peroxidation was seen in vitamin E deficiency but an increase in dietary vitamin E content did not provide additional protection compared to the recommended daily allowance. The antioxidant acitivities of α-tocopherol and γ-enriched tocotrienol were similar.     

Study of oxidative stress and trace element levels in patients with alcoholic and non-alcoholic coronary artery disease

Alcohol consumption induces oxidative stress, and leads to lipid peroxidation. These effects have been linked to alcohol-related toxicity and diseases are considered relevant to alcohol-atherosclerosis interrelationship. Deficiency of many antioxidants and trace elements may impair the antioxidant defense leading to ethanol induced oxidative stress. In the present study, our aim was to investigate the lipid peroxidation, lipid profile, antioxidant enzymes and trace elements in patients with and without alcoholic coronary artery disease (CAD). Our study included 61 patients suffering from CAD, 124 patients suffering from alcoholic CAD with high to moderate alcohol intake, 75 controls were randomly selected for our study. Increased serum lipid peroxidation, total cholesterol, triglycerides, LDL cholesterol and copper levels were high while levels of HDL cholesterol, glutathione peroxdiase, superoxide dismutase, trace elements like Selenium and Zinc were low in high alcoholic CAD patients compared with moderate and non alcoholic CAD patients. The results obtained from present study indicate that high alcohol intake predicts low antioxidant enzyme and that trace element may contribute to the increased susceptibility for the development of CAD.     

The influence of exogenous antioxidants and physical exercise on some parameters associated with production and removal of free radicals

Metabolic processes generate chemically active forms of oxygen, among which a prominent role is played by the superoxide ion. Cells are equipped with defence systems against the effects of superoxide radicals, superoxide dismutase is the most important one. The organism depends on the delivery of exogenous antioxidants, like selenium, vitamins E and C. Physical exercise triggers the production of superoxide radicals, which can at least partly be responsible for muscular damage. This work has studied the effect of Protection Zellaktiv (Smith Kline Beecham, Fink Naturarznei GmbH), a preparation containing selenium, vitamins C, E, B2, niacin and beta-carotene on the activities of superoxide dismutase and catalase, levels of glutathione malondialdehyde selenium, iron, zinc, triglicerides, total cholesterol, HDL- and LDL-cholesterol, before and after physical exercise. Muscle status was monitored by the activities of lactic dehydrogenase and creatine kinase. Protecton Zellaktiv was administered orally for one month, the measurements were repeated and the results before and after treatment were compared. It was found that treatment diminished the levels of malondialdehyde and zinc in serum, as well as cholesterol and triglicerides. Physical exercise before treatment decreased the levels of reduced glutatione, zinc and triglycerides. As expected, the levels of selenium were increased by the preparation. Protecton Zellaktiv suppressed the production of malondialdehyde during physical exercise. The preparation had a beneficial effect on lipid levels and it is inferred that lipid peroxidation was suppressed.     

Modulatory effects of curcumin on lipid peroxidation and antioxidant status during nicotine-induced toxicity

Nicotine, a pharmacologically active substance in tobacco, has been identified as a major risk factor for lung diseases. In the present study, we evaluated the protective effects of curcumin on tissue lipid peroxidation and antioxidants in nicotine-treated Wistar rats. Lung toxicity was induced by subcutaneous injection of nicotine at a dose of 2.5 mg/kg (5 days a week, for 22 weeks). Curcumin (80 mg/kg) was given simultaneously by intragastric intubation for 22 weeks. The enhanced level of tissue lipid peroxides in nicotine-treated rats was accompanied by a significant decrease in the levels of ascorbic acid, vitamin E, reduced glutathione, glutathione peroxidase, superoxide dismutase and catalase. Administration of curcumin significantly lowered the level of lipid peroxidation and enhanced the antioxidant status. The results of the present study suggest that curcumin exerts its protective effect against nicotine-induced lung toxicity by modulating the extent of lipid peroxidation and augmenting antioxidant defense system.     

Ameliorative effects of black tea extract on aflatoxin-induced lipid peroxidation in the liver of mice.

We have evaluated the ameliorative effect of black tea extract on aflatoxin-induced lipid peroxidation in the liver of mice. Adult male albino mice were orally administered with 25 and 50 microg of aflatoxin in 0.2 ml olive oil/animal/day for 30 days. Results revealed dose-dependent and significantly (p<0.05) higher lipid peroxidation in the liver of aflatoxin-treated mice than that of vehicle control. As compared with vehicle control, the levels of non-enzymatic antioxidants such as glutathione and ascorbic acid, as well as the enzymatic antioxidants such as superoxide dismutase, glutathione peroxidase and catalase were significantly (p<0.05) lowered in the liver of aflatoxin-treated mice. Oral administration of two percent aqueous black tea extract along with aflatoxin for 30 days (groups 6 and 7) caused significant (p<0.05) amelioration in aflatoxin-induced lipid peroxidation by increasing significantly (p<0.05) the activities of enzymatic (superoxide dismutase, glutathione peroxidase, catalase) and contents of non-enzymatic (glutathione and ascorbic acid) antioxidants in the liver of mice as compared with those given aflatoxin alone (groups 4 and 5). Thus, oral administration of black tea along with aflatoxin significantly (p<0.05) ameliorates aflatoxin-induced lipid peroxidation in the liver of mice.     

S-allylcysteine inhibits circulatory lipid peroxidation and promotes antioxidants in N-nitrosodiethylamine-induced carcinogenesis

Effects of S-allylcysteine (SAC), an organosulfur compound of garlic, on circulatory lipid peroxidation and antioxidant levels were evaluated in N-nitrosodiethylamine (NEDA)-induced hepatocarcinogenesis in Wistar rats. Significantly elevated thiobarbituric acid reactive substances in the circulation of rats bearing carcinoma indicated the higher levels of lipid peroxidation which was accompanied by significantly decreased levels of antioxidants (beta-carotene, ascorbic acid, alpha-tocopherol, reduced glutathione, glutathione peroxidase, superoxide dismutase and catalase) when compared with controls. Lipid peroxidation has been implicated as a major cause in cancer development. SAC-administered rats showed the inhibition of tumor incidence and lipid peroxidation with simultaneous elevation in antioxidants. We suggest that SAC exerts its chemopreventive effects by decreasing lipid peroxidation and enhancing the levels of antioxidants in NDEA carcinogenesis by reducing the formation of free radicals.     

Amelioration of corticosteroid-induced type 2 diabetes mellitus by rosiglitazone is possibly mediated through stimulation of thyroid function and inhibition of tissue lipid peroxidation in mice

We investigated the possible involvement of thyroid hormones and lipid peroxidation in the antidiabetic potential of rosiglitazone (a peroxisome proliferator-activated receptors gamma-agonist) on corticosteroid-induced type 2 diabetes mellitus. Rosiglitazone was administered to dexamethasone-induced hyperglycaemic male mice and the alterations in serum concentrations of thyroid hormones insulin, total cholesterol, triglycerides and fasting glucose were studied. Simultaneously changes in lipid peroxidation, reduced glutathione (GSH) content, superoxide dismutase and catalase activities in renal and cardiac tissues (which are commonly affected in diabetes mellitus), were also investigated. Administration of dexamethasone (1.0 mg/kg/day intramuscularly for 28 days) caused hyperglycaemia with a parallel increase in serum insulin, total cholesterol, triglycerides and tissue lipid peroxidation with a decrease in serum levels of both the thyroid hormones (triiodothyronine, T(3) and thyroxine, T(4)) and in the activity of associated tissue antioxidants such as superoxide, catalase and glutathione. However, rosiglitazone administration (3.2 mg/kg/day orally for 21 days) along with an equivalent amount of dexamethasone reverted most of these changes, including a marked inhibition of tissue lipid peroxidation and an increase in the serum levels of both thyroid hormones. The present findings reveal that the test drug ameliorates corticosteroid-induced type 2 diabetes mellitus through an increase in serum thyroid hormone concentrations and inhibition in tissue lipid peroxidation.     

Formation and removal of active oxygen species and lipid peroxides in biological systems]

The mechanisms of formation and removal of active oxygen species and lipid peroxides in biological systems have been briefly reviewed. Cytotoxic active oxygen species can be classified into two types: (a) radical species such as O2-. (superoxide) and HO. (hydroxyl radical) and (b) non-radical species such as H2O2 (hydrogen peroxide) and 1O2 (singlet oxygen). The direct or indirect attack of active oxygen species on polyunsaturated fatty acids, essential constituents of biological membranes, has been shown to result in the formation of a number of peroxidative lipid breakdown-products: LOOH (lipid hydroperoxide), LOO. (lipid peroxyl radical) and LO. (lipid alkoxyl radical). The lipid peroxide decomposition is probably dependent on the presence of ferric-ferrous ions. These processes are called lipid peroxidation reactions. In recent years, there has been a renewed interest in the role played by lipid peroxidation in many disease states. The multiple lines of defense against toxic oxygen intermediates consist of enzymatic systems, glutathione peroxidase, catalase and superoxide dismutase, and furthermore involves antioxidant capacities such as those of vitamin E and vitamin C. In biological systems, there are naturally occurring lipid-soluble (vitamin E and ubiquinone) and water-soluble (vitamin C, reduced glutathione and uric acid) antioxidants. Therefore, so long as homeostasis is maintained between the rate of radical generation and the rate of radical dissipation, the cellular generation of radicals may not be harmful. In contrast, this balance can be disturbed if cellular defenses are decreased or if there is a significant increase in the flux of radical generation. Once lipid peroxidation is initiated, the reactive intermediate formed induces cell damage.(ABSTRACT TRUNCATED AT 250 WORDS)     

Erythrocyte redox status in streptozotocin diabetic rats: effect of Casearia esculenta root extract

The present study was aimed to investigate the effect of Casearia esculenta root extract on erythrocyte lipid peroxidation and to assess the status of antioxidants in red blood cells of streptozotocin (STZ) diabetic rats. The study showed a significant elevation (p < 0.05) of erythrocyte thiobarbituric acid reactive substances (TBARS), an index of lipid peroxidation and significant reduction (p < 0.05) in reduced glutathione (GSH), ascorbic acid (vitamin C), alpha-tocopherol (vitamin E), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) in the STZ diabetic rats. The study also observed significant reduction in membrane cholesterol and phospholipid content in STZ diabetic rats. By oral administration of C. esculenta (200 and 300 mg/kg body wt.) for 45 days to the diabetic rats these values approached almost normal levels. A dose of 300 mg/kg body weight C. esculenta extract showed better antioxidant effects than 200 mg/kg body weight.     

Influence of naringenin on oxytetracycline mediated oxidative damage in rat liver

Naringenin is a naturally occurring citrus flavanone, which has been reported to have a wide range of pharmacological properties. The present work was carried out to evaluate the effect of naringenin on antioxidant and lipid peroxidation status in liver of oxytetracycline-intoxicated rats. Intraperitonial administration of oxytetracycline 200 mg/kg for 15 days resulted a significant elevation in serum hepatospecific markers such as aspartate transaminase, alanine transaminase, alkaline phosphatase, lactate dehydrogenase, and bilirubin and the levels of lipid peroxidation markers (thiobarbituric acid reactive substances (TBARS) and lipid hydroperoxides) in liver. Oxytetracycline also caused a significant reduction in the activities of superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione (GSH), vitamin C and vitamin E in liver. Oral administration of naringenin (50 mg/kg b.w.t.) with oxytetracycline significantly decreased the activities of serum aspartate transaminase, alanine transaminase, alkaline phosphatase, lactate dehydrogenase and the levels of bilirubin along with significant decrease in the levels of lipid peroxidation markers in the liver. In addition, naringenin significantly increased the activities of superoxide dismutase, catalase and GSH peroxidase as well as the level of GSH, vitamin C and vitamin E in liver of the oxytetracycline-treated rats. Our results demonstrate that naringenin exhibited antioxidant property and decrease the lipid peroxidation against oxytetracycline-induced oxidative stress in liver.     

Effects of the peroxisome proliferators ciprofibrate and perfluorodecanoic acid on hepatic cellular antioxidants and lipid peroxidation in rats.

The purpose of this study was to determine if hepatic cellular antioxidants and indices of oxidative damage are altered by administration of the peroxisome proliferators ciprofibrate and perfluorodecanoic acid (PFDA). Rats were fed 0.01% ciprofibrate in the diet or were injected with PFDA (0.5 or 5.0 mg/kg, i.p.) every 4 weeks for 6, 14, 30, 54, and 78 weeks. Peroxisomal fatty acyl-CoA oxidase and catalase activities were increased by both ciprofibrate and PFDA throughout the study. Neither ciprofibrate nor PFDA increased the levels of malonaldehyde or conjugated dienes, but ciprofibrate decreased these indices at early time points. Ciprofibrate decreased the following cellular antioxidants or antioxidant enzymes: vitamin C, vitamin D, DT-diaphorase, glutathione peroxidase, glutathione-S-transferase, and glutathione reductase; superoxide dismutase and glutathione were not affected. PFDA decreased DT-diaphorase and increased superoxide dismutase, but did not affect other cellular antioxidants. This study shows that administration of the peroxisome proliferators ciprofibrate and PFDA did not increase indices of lipid peroxidation, but that cellular antioxidant defenses were inhibited for a prolonged period of time by the peroxisome proliferator ciprofibrate.