Propolis protects CYP 2E1 enzymatic activity and oxidative stress induced by carbon tetrachloride

Induction of CYP 2E1 by carbon tetrachloride (CCl₄) is one of the central pathways by which CCl₄ generates oxidative stress in hepatocytes. Experimental liver injury was induced in rats by CCl₄ to determine toxicological actions on CYP 2E1 by microsomal drug metabolizing enzymes. In this report, ethanolic extract of propolis at a dose of 200 mg/kg (po) was used after 24 h of toxicant administration to validate its protective potential. Intraperitoneal injection of CCl₄ (1.5 ml/kg) induced hepatotoxicity after 24 h of its administration that was associated with elevated malonyldialdehyde (index of lipid peroxidation), lactate dehydrogenase and γ-glutamyl transpeptidase release (index of a cytotoxic effect). Hepatic microsomal drug metabolizing enzymes of CYP 2E1 showed sharp depletion as assessed by estimating aniline hydroxylase and amidopyrine N-demethylase activity after CCl₄ exposure. Toxic effect of CCl₄ was evident on CYP 2E1 activity by increased hexobarbitone induced sleep time and bromosulphalein retention. Propolis extract showed significant improvement in the activity of both enzymes and suppressed toxicant induced increase in sleep time and bromosulphalein retention. Choleretic activity of liver did not show any sign of toxicity after propolis treatment at a dose of 200 mg/kg (id). Histopathological evaluation of the liver revealed that propolis reduced the incidence of liver lesions including hepatocyte swelling and lymphocytic infiltrations induced by CCl₄. Electron microscopic observations also showed improvement in ultrastructure of liver and substantiated recovery in biochemical parameters. Protective activity of propolis at 200 mg/kg dose was statistically compared with positive control silymarin (50 mg/kg, po), a known hepatoprotective drug seems to be better in preventing hepatic CYP 2E1 activity deviated by CCl₄. These results lead us to speculate that propolis may play hepatoprotective role via improved CYP 2E1 activity and reduced oxidative stress in living system.     

Effect of vitamin E supplementation on diabetes induced oxidative stress in experimental diabetes in rats

Diabetes induced by streptozotocin (50 mg/kg body wt, i.p.) in the rats substantially increased the plasma glucose and malondialdehyde levels along with corresponding decrease in the antioxidants levels. Supplementation of vitamin E (200 mg/kg body wt., ip) for 5 weeks resulted in non-significant decrease in the blood glucose levels but plasma malondialdehyde levels were reduced to below normal levels. Plasma vitamin E, vitamin C, uric acid and red blood cell glutathione levels were also restored to near normal levels on vitamin E supplementation to diabetic rats as compared to control (diabetic) rats. The activities of antioxidant enzymes, catalase (EC 1.11.1.6), glutathione peroxidase (GSHPx EC 1.11.1.9), and glutathione reductase (GR EC 1.6.4.2) were also concomitantly restored to near normal levels by vitamin E supplementation to diabetic rats. The results clearly demonstrated that vitamin E supplementation augments the antioxidant defense mechanism in diabetes and provides evidence that vitamin E may have a therapeutic role in free radical mediated diseases.     

Vitamin E prevents nonylphenol-induced oxidative stress in testis of rats

In the present study we have investigated if administration of nonylphenol-induced oxidative stress in various subcellular fractions of adult rat testis and the effect of vitamin E on reactive oxygen species mediated nonylphenol toxicity. Male rats were administered orally with nonylphenol at 1, 10 and 100 microg/kg body weight per day for 45 days with and without supplementation of vitamin E (20 mg/kg body weight). In nonylphenol-treated rats the activities of antioxidant enzymes superoxide dismutase and glutathione reductase decreased significantly while the levels of lipid peroxidation increased significantly in the crude homogenate and in the mitochondrial and microsome-rich fractions of testis. Co-administration of nonylphenol and vitamin E did not cause changes in the activities of antioxidant enzymes in various subcellular fractions of rat testis. The results suggest that graded doses of nonylphenol elicit depletion of antioxidant defence system in rat testis, indicating nonylphenol induced oxidative stress in the testis of rats which could be reversed by the administration of vitamin E.     

Comparison of vitamin E, L-carnitine and melatonin in ameliorating carbon tetrachloride and diabetes induced hepatic oxidative stress

This study aimed to investigate whether treatments with vitamin E, L-carnitine and melatonin can protect against CCl₄ and diabetes-induced hepatic oxidative stress. Hepatic oxidative stress was performed in rats through 50% v/v carbon tetrachloride (CCl₄) (1 ml/kg/3days, i.p.), and through diabetes mellitus induced by streptozotocin (STZ) (40 mg/kg, i.p.). Vitamin E (100 mg/kg/day, i.p), L-carnitine (300 mg/kg/day, i.p.) and melatonin (10 mg/kg/day, i.p.) were injected for a period of 6 weeks. Thereafter, changes in serum glucose level, liver function tests, hepatic malondialdehyde (MDA) content, hepatic reduced glutathione (GSH) content, hepatic superoxide dismutase (SOD) activity, and serum total antioxidant capacity (TAC) level were evaluated. In CCl₄-induced liver fibrosis, the efficacy order was melatonin > L-carnitine > vitamin E, while in STZ-induced diabetes, the efficacy order was vitamin E ≥ melatonin > L-carnitine. In conclusion, these data indicate that low dose of melatonin is more effective than high doses of vitamin E and L-carnitine in reducing hepatic oxidative stress induced by CCl₄ and diabetes. Moreover, the potent effect of vitamin E in ameliorating diabetes can be linked not only to the antioxidant actions, but also to the superior effect in reducing diabetes-induced hyperglycaemia. Meanwhile, potency of L-carnitine was nearly the same in CCl₄ and diabetes-induced liver damage.     

Vitamin E and oxidative stress

Oxidative stress can result from or be enhanced by a large variety of conditions, including nutritional imbalance, exposure to chemical and physical agents in the environment, strenuous physical activities, injury, and hereditary disorders. While many enzymes and compounds are involved in protecting cells from the adverse effects of oxidative stress, vitamin E occupies an important and unique position in the overall antioxidant defense. The antioxidant function of vitamin E is closely related to the status of many dietary components. Vitamin E-depleted animals are generally more susceptible to the adverse effects of environmental agents than supplemented animals. Also, vitamin E supplementation is beneficial to certain groups of the population. However, supplementing vitamin E in experimental subjects maintained on a nutritionally adequate diet does not always provide additional protection. Differential metabolic responses in various organs and differences in experimental conditions often contribute in the discrepancies in the literature. The lack of clear evidence for the occurrence of lipid peroxidation or antioxidant function of vitamin E in vivo can be attributed partly to the presence of active pathways for metabolizing hydroperoxides, aldehydes, and other oxidation products. Specific and sensitive techniques for measuring lipid peroxidation products in biological systems are essential for understanding the role of free radical-induced lipid peroxidation in tissue damage and antioxidant function of vitamin E in vivo.     

Vitamin C or Vitamin B6 supplementation prevent the oxidative stress and decrease of prostacyclin generation in homocysteinemic rats

We hypothesize that homocysteinemia causes oxidative stress, decreases the aortic ability to generate prostacyclin and that antioxidants have a protective role. Four groups of eight rats each were fed for 8 weeks the control diet (group A), control diet with folic acid omitted and excess methionine (Me) added to drinking water (group B), diet B + 500 mg/kg of Vitamin C (group C) or diet B + 60 mg/kg Vitamin B6 (group D). The three groups of rats fed folic acid deficient (FD) diets (groups B, C and D) were homocysteinemic as indicated by the significant increase in their serum homocysteine (HC) concentration. Rats fed diet B had oxidative stress as indicated by an increase in serum thiobarbituric acid reactive substances (TBARS) and advanced oxidation protein products (AOPP) and urinary isoprostanes and had a decreased ability of their aortas to generate prostacyclin. Homocysteinemic rats fed a FD diet + Vitamin C (group C) or Vitamin B6 (group D) also had high levels of serum homocysteine but the oxidative stress markers and the ability of their aortas to generate prostacyclin returned to normal. This indicates that the homocysteinemic effect is through an oxidative mechanism and that Vitamin C as a free radical scavenger prevents these effects. Serum Vitamin C and liver glutathione concentrations significantly increased in rats fed excess Vitamin B6 compared to the control or FD rats. This may explain why Vitamin B6 has an antioxidative effect.     

Protective role of Vitamin E pre-treatment on N-nitrosodiethylamine induced oxidative stress in rat liver

Nitrosamine compounds are known hepatic carcinogens. In the metabolism of nitrosamines, such as N-nitrosodiethylamine (NDEA), there is evidence of the formation of reactive oxygen species (ROS) resulting in oxidative stress, which may be one of the factors in the etiology of cancer. The formation of ROS may alter the antioxidant system, while the presence of Vitamin E may counteract NDEA induced oxidative stress. This study was planned to determine whether pre-treatment with Vitamin E (40 mg/kg body weight, i.p., twice a week for 4 weeks) to NDEA induced rats provides protection against oxidative stress in liver caused by the carcinogen. A single necrogenic dose of NDEA (200mg/kg body weight) was administered i.p. to the male albino rats with or without Vitamin E pre-treatment and the animals were sacrificed on Days 7, 14 or 21 after the administration of NDEA. The result showed enhanced levels of hepatic lipid peroxidation (LPO) and conjugated dienes of NDEA treated rats as the indices of oxidative stress, however, Vitamin E pre-treated rats administered NDEA showed decreased LPO and conjugated dienes (Day 21). Superoxide dismutase (SOD) activity in liver was not altered significantly in NDEA treated rats with or without Vitamin E pre-treatment. Catalase (CAT) activity was inhibited with NDEA treatment, however, Vitamin E pre-treatment showed recovery in hepatic CAT activity (Days 14 and 21). Total and Se-glutathione peroxidase (GSH-Px) activities and glutathione-S-transferase (GST) activity in liver increased in NDEA treated rats irrespective of Vitamin E pre-treatment. Glutathione reductase (GSH-R) activity as well as total glutathione (GSH) content in liver decreased in NDEA treated animals, both of which were recovered in Vitamin E pre-treated rats administered NDEA. Activities of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP) and lactate dehydrogenase (LDH) were increased significantly following NDEA treatment to rats with or without Vitamin E pre-treatment. The activities of AST and ALT enzymes were significantly reduced on Days 14 and 21 and ALP activity was reduced on Day 21 in NDEA+Vitamin E treated animals when compared to NDEA treated alone. LDH enzyme activity was normalized on Day 14 in Vitamin E pre-treated animals administered NDEA. However, the AST, ALT and ALP enzyme activities remained high in all treatment groups as compared to control group. Normal control and Vitamin E treated alone rats revealed normal histology of liver. On the other hand, NDEA treated animals showed alterations in normal hepatic histoarchitecture, which comprised of necrosis and vacuolization of the cells. However, the rats treated with Vitamin E+NDEA showed that the liver cells were normal, with very little necrosis (Day 21). This study concludes that the pre-treatment with Vitamin E prior to the administration of NDEA, reduced the degree of oxidative stress, although this vitamin produced only slight changes in the hepatic injury, in a time-dependent manner.     

Hepatoprotective potential of Ferula communis extract for carbon tetrachloride induced hepatotoxicity and oxidative damage in rats

ABSTRACT

We investigated the hepatoprotective potential of Ferula communis extract for CCI₄ induced liver damage. We used six groups of rats: group 1, untreated control; group 2, CCl₄ treated (hepatotoxic); group 3, treated with 150 mg/kg F. communis; group 4, treated with 300 mg/kg F. communis; group 5, treated with CCl₄ + 150 mg/kg F. communis; and group 6, treated with CCl₄ + 300 mg/kg F. communis. Liver damage was produced by injection of 1 ml/kg CCI₄ twice/week. Extracts of F. communis, 150 and 300 mg/kg/day, were administered for 8 weeks. The effects of F. communis were assessed by measuring aspartate aminotransferase (AST), alanine aminotransferase (ALT), γ-glutamyl transferase (GGT) and total bilirubin (T-BIL) levels, and the activities of antioxidant enzymes, superoxide dismutase (SOD) and glutathione peroxidase (GPx) in the liver. The histology and immunohistochemistry of liver tissue were evaluated using hematoxylin and eosin staining, and caspase 3 and 8-OHdG immunostaining. F. communis extract produced significant reductions in elevated levels of ALT, AST, GGT and T-BIL and increased levels of GPx and SOD in rats treated with CCl₄. F. communis extract decreased CCl₄ induced 8-OHdG formation and caspase 3 activation significantly in hepatocytes, especially at the 150 mg/kg dose. Our findings demonstrate the potential efficacy of F. communis for attenuating CCl₄ induced hepatotoxicity and oxidative damage.     

Vitamin E prevents cell death induced by mild oxidative stress in chicken skeletal muscle cells

Apoptosis and necrosis are two forms of cell death that can occur in response to various agents and oxidative damage. In addition to necrosis, apoptosis contributes to muscle fiber loss in various muscular dystrophies as well participates in the exudative diathesis in chicken, pathology caused by dietary deficiency of vitamin E and selenium, which affects muscle tissue. We have used chicken skeletal muscle cells and bovine fibroblasts to study molecular events involved in the cell death induced by oxidative stress and apoptotic agents. The effect of vitamin E on cell death induced by oxidants was also investigated. Treatment of cells with anti-Fas antibody (50 to 400 ng/mL), staurosporine (0.1 to 100 microM) and TNF-alpha (10 and 50 ng/mL) resulted in a little loss of Trypan blue exclusion ability. Those stimuli conducted cells to apoptosis detected by an enhancement in caspase activity upon fluorogenic substrates but this activity was not fully blocked by the caspase inhibitor Z-VAD-fmk. Oxidative stress induced by menadione (10, 100 and 250 muM) promoted a significant reduction in cell viability (10%, 20% and 35% for fibroblasts; 20%, 30% and 75% for muscle cells, respectively) and caused an increase in caspase activity and DNA fragmentation. H2O2 also promoted apoptosis verified by caspase activation and DNA fragmentation, but in higher doses induced necrosis. Vitamin E protected cells from death induced by low doses of oxidants. Although it was ineffective in reducing caspase activity in fibroblasts, this vitamin diminished the enzyme activity in muscle cells. These data suggested that oxidative stress could activate apoptotic mechanisms; however the mode of cell death will depend on the intensity and duration of the stimulus, and on the antioxidant status of the cells.     

Vitamin E and regression of hypercholesterolemia-induced oxidative stress in kidney

Hypercholesterolemia (HC) is an independent risk factor for the onset and progression of renal disease. HC induces oxidative stress (OS) in the kidney; Vitamin E (Vit.E), an antioxidant, slows the progression of OS in the kidney. This study was to investigate if Vit.E regresses the HC-induced OS, and the regression is associated with an increase in the antioxidant reserve (AR). The studies were carried out in four groups of rabbits. The kidneys were removed under anesthesia. OS and AR in the renal tissue were assessed by measuring malondialdetyde (MDA) and chemiluminescent (CL) activity, respectively. High-cholesterol diet elevated the serum total cholesterol (TC), and the regular diet with or without Vit.E following a high-cholesterol diet reduced the serum TC to control levels. HC increased the MDA levels of kidney by 5.54-fold compared to control. The MDA contents of the kidneys in groups on regular diet with or without Vit.E were, respectively, 56 and 53 % lower than the control group. The CL activity in the control group was 12.15 ± 0.73 × 10⁶ RLU/mg protein. The CL activity in HC group was 45.26 % lower than that in control, indicating an increase in AR. The regular diet with or without Vit.E following high-cholesterol diet normalized the CL activity/AR. In conclusion, HC increases OS in the kidney; reduction of serum cholesterol by regular diet regresses the renal OS but Vit.E does not regress HC-induced OS in kidney.     

Vitamin E does not regress hypercholesterolemia-induced oxidative stress in heart

Vitamin E suppresses the hypercholesterolemia-induced cardiac oxidative stress. The objectives were to investigate: if vitamin E regresses the hypercholesterolemia-induced oxidative stress in hearts and if regression is associated with decreases in the antioxidant reserve. The rabbits were assigned to 4 groups: I, regular diet (2-months); II, 0.25 % cholesterol diet (2-months); III, 0.25 % cholesterol diet (2-months) followed by regular diet (2-months); and IV, 0.25 % cholesterol diet (2-months) followed by regular diet with vitamin E (2-months). Blood samples were collected before and at the end of protocol for the measurement of total cholesterol (TC). Hearts were removed at the end of the protocol under anesthesia for the assessment of oxidative stress parameters, malondialdehyde (MDA), and tissue chemiluminescent (CL) activity. High cholesterol diet increased the serum levels of TC, and regular diet with or without vitamin E reduced the TC levels to a similar extent. The MDA content of the heart in groups I, II, III, and IV were 0.074 ± 0.015, 0.234 ± 0.016, 0.183 ± 0.028 and 0.169 ± 0.016 nmol/mg protein, respectively. Regular diet following high cholesterol diet reduced the MDA levels (0.234 ± 0.016 vs. 0.183 ± 0.028 nmol/mg protein but vitamin E did not reduce the MDA levels. The cardiac-CL activities were similar in groups’ I, II, and III (30.11 ± 0.7 × 10⁶, 32.9 ± 1.43, and 37.92 ± 8.35 × 10⁶ RLU/mg protein). The activity decreased in group IV, suggesting that vitamin E increased the antioxidant reserve while lowering serum cholesterol did not increase antioxidant reserve. In conclusion, hypercholesterolemia increases cardiac oxidative stress and regular diet regresses hypercholesterolemia-induced oxidative stress but vitamin E does not further regress hypercholesterolemia-induced cardiac oxidative stress. Vitamin E reduces oxidative stress in the heart tissue in spite of a decrease in CL activity (increase in antioxidant reserve).     

Effect of vitamin E on monosodium glutamate induced hepatotoxicity and oxidative stress in rats

Monosodium glutamate (MSG), administered to rats (by gavage) at a dose of 0.6 mg/g body weight for 10 days, significantly (P<0.05) induced lipid peroxidation (LPO), decreased reduced glutathione (GSH) level and increased the activities of glutathione-s-transferase (GST), catalase and superoxide dismutase (SOD) in the liver of the animals; these were observed 24 hr after 10 days of administration. The activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma glutamyl transferase (GGT) were also significantly increased in the serum, on MSG administration. Vitamin E (0.2 mg/g body wt) co-administered with MSG, significantly reduced the LPO, increased the GSH level and decreased the hepatic activities of GST, catalase and SOD. The activities of ALT, AST and GGT in the serum were also significantly reduced. The results showed that MSG at a dose of 0.6 mg/g body wt induced the oxidative stress and hepatotoxicity in rats and vitamin E ameliorated MSG-induced oxidative stress and hepatotoxicity.     

Protective effects of ascorbic acid on hepatotoxicity and oxidative stress caused by carbon tetrachloride in the liver of Wistar rats

This study was planned to investigate the protective effect of l (+)‐ascorbic acid (Vit C) on CCl₄‐induced hepatotoxicity and oxidative stress in the liver of Wistar rats (Rattus Norvegicus, strain Wistar). Twenty‐four adult male Wistar rats were fed with standard rat chow diet for 10 days and randomly were divided into four groups of six each as follows: (1) control, (2) CCl₄, (3) “CCl₄ + Vit C”, (4) Vit C groups. CCl₄ was applied to rats belonging to CCl₄ and “CCl₄ + Vit C” groups subcutaneously at 1 mg kg^?1 dose CCl₄ for 3 days. Vit C applied to “CCl₄ + Vit C” and “Vit C” group rats intraperitoneally at 300 mg kg^?1 dose for 3 days. All rats were sacrificed and livers were quickly removed on the fourth day of the experiment. MDA, total glutathione (T.GSH) levels and superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH‐PX) activities were measured in the liver of all groups of rats and also serum alanine amino transferase (ALT) and aspartate amino transferase (AST) activities were detected to determine liver functions in all groups of rats. Histopathological changes were evaluated by light and transmission electron microscopes. In “CCl₄ + Vit C” group, MDA level was significantly decreased (p < 0.05) and SOD, CAT, GSH‐PX activities were significantly increased (p < 0.005, 0.01, 0.05) respectively, T.GSH level was significantly increased (p < 0.005) and serum ALT and AST activities were significantly decreased (p < 0.01, 0.05), respectively, when compared with CCl₄ group. These results show that Vit C has a highly protective effect on hepatotoxicity and oxidative stress caused by CCl₄. Copyright © 2009 John Wiley & Sons, Ltd.     

Vitamin C prevents DNA mutation induced by oxidative stress

The precise role of vitamin C in the prevention of DNA mutations is controversial. Although ascorbic acid has strong antioxidant properties, it also has pro-oxidant effects in the presence of free transition metals. Vitamin C was recently reported to induce the decomposition of lipid hydroperoxides independent of metal interactions, suggesting that it may cause DNA damage. To directly address the role of vitamin C in maintaining genomic integrity we developed a genetic system for quantifying guanine base mutations induced in human cells under oxidative stress. The assay utilized a plasmid construct encoding the cDNA for chloramphenicol acetyl transferase modified to contain an amber stop codon, which was restored to wild type by G to T transversion induced by oxidative stress. The mutation frequency was determined from the number of plasmids containing the wild type chloramphenicol acetyl transferase gene rescued from oxidatively stressed cells. Cells were loaded with vitamin C by exposing them to dehydroascorbic acid, thereby avoiding transition metal-related pro-oxidant effects of ascorbic acid. We found that vitamin C loading resulted in substantially decreased mutations induced by H(2)O(2). Depletion of glutathione led to cytotoxicity and an increase in H(2)O(2)-induced mutation frequency; however, mutation frequency was prominently decreased in depleted cells preloaded with vitamin C. The mutation results correlated with a decrease in total 8-oxo-guanine measured in genomic DNA of cells loaded with vitamin C and oxidatively stressed. These findings directly support the concept that high intracellular concentrations of vitamin C can prevent oxidation-induced mutations in human cells.     

Vitamin E supplementation for the ruminant

Vitamin E is essential for such body functions as growth, reproduction, prevention of various diseases, and for integrity of tissues. The most significantly important result of selenium and vitamin E deficiency is tissue degeneration (e.g. white muscle disease). Vitamin E does not cross the placenta in any appreciable amounts; however, it is concentrated in colostrum. Supplemental vitamin E can greatly increase colostral tocopherol. The importance of providing colostrum rich in vitamin E is essential as both calves and lambs are born with low levels of the vitamin. Vitamin E has been shown to increase performance of feedlot cattle and to increase immune response for ruminant health, including being beneficial for mastitis control. Vitamin E given to finishing cattle at higher than National Research Council (NRC) requirements dramatically maintained the red color (oxymyoglobin) compared with the oxidized metmyoglobin of beef. It appears that supplementation of 500 IU vitamin E per head daily for 84–126 days yields tissue -tocopherol that would maintain a favorable level of oxymyoglobin in meat, thus increasing its value. Vitamin E nutritional status is commonly estimated from plasma concentration, with a high correlation between plasma and liver levels of -tocopherol. The NRC estimates for vitamin E requirements of beef cattle, dairy cattle and sheep to range from 15 to 40 mg kg⁻¹; however, higher levels will likely improve performance, and megadose levels will improve carcass quality.     

Vitamin E may slow kidney failure owing to oxidative stress

Summary

Progression to kidney failure in a number of major renal diseases is now thought to be significantly worsened by oxidative stress at the biochemical level. Evidence is accumulating that the rate of deterioration could, in many cases, be slowed down to a more acceptable level by the simple expedient of dietary supplementation with the antioxidant, vitamin E. Evidence for the potential use of vitamin E as an adjunctive therapy to help prolong kidney function in conditions that are accelerated by oxidative stress is discussed.     

Hepatoprotective activity of ellagic acid against carbon tetrachloride induced hepatotoxicity in rats

Administration of CCl4 to normal rats and consequent oral feeding with ellagic acid (50 mg/kg) provided a significant protection against the biochemical alterations in serum and liver produced by CCl4. In vitro experiments showed that liver microsomes from animals treated with ellagic acid and CCl4, decreased lipid peroxidation compared to microsome prepared from rats exposed to CCl4 alone.