Lipid hydroperoxide induced mitochondrial dysfunction following acute ethanol intoxication in rats. The critical role for mitochondrial reduced glutathione

The 2-oxoglutarate carrier promotes liver cancer by sustaining mitochondrial GSH despite cholesterol loading

Cancer cells exhibit mitochondrial cholesterol (mt-cholesterol) accumulation, which contributes to cell death resistance by antagonizing mitochondrial outer membrane (MOM) permeabilization. Hepatocellular mt-cholesterol loading, however, promotes steatohepatitis, an advanced stage of chronic liver disease that precedes hepatocellular carcinoma (HCC), by depleting mitochondrial GSH (mGSH) due to a cholesterol-mediated impairment in mGSH transport. Whether and how HCC cells overcome the restriction of mGSH transport imposed by mt-cholesterol loading to support mGSH uptake remains unknown. Although the transport of mGSH is not fully understood, SLC25A10 (dicarboxylate carrier, DIC) and SLC25A11 (2-oxoglutarate carrier, OGC) have been involved in mGSH transport, and therefore we examined their expression and role in HCC. Unexpectedly, HCC cells and liver explants from patients with HCC exhibit divergent expression of these mitochondrial carriers, with selective OGC upregulation, which contributes to mGSH maintenance. OGC but not DIC downregulation by siRNA depleted mGSH levels and sensitized HCC cells to hypoxia-induced ROS generation and cell death as well as impaired cell growth in three-dimensional multicellular HCC spheroids, effects that were reversible upon mGSH replenishment by GSH ethyl ester, a membrane permeable GSH precursor. We also show that OGC regulates mitochondrial respiration and glycolysis. Moreover, OGC silencing promoted hypoxia-induced cardiolipin peroxidation, which reversed the inhibition of cholesterol on the permeabilization of MOM-like liposomes induced by Bax or Bak. Genetic OGC knockdown reduced the ability of tumor-initiating stem-like cells to induce liver cancer. These findings underscore the selective overexpression of OGC as an adaptive mechanism of HCC to provide adequate mGSH levels in the face of mt-cholesterol loading and suggest that OGC may be a novel therapeutic target for HCC treatment.

Proteomic analysis of mice fed methionine and choline deficient diet reveals marker proteins associated with steatohepatitis

The mechanisms underlying the progression of simple steatosis to steatohepatitis are yet to be elucidated. To identify the proteins involved in the development of liver tissue inflammation, we performed comparative proteomic analysis of non-alcoholic steatohepatitis (NASH). Mice fed a methionine and choline deficient diet (MCD) developed hepatic steatosis characterized by increased free fatty acid (FFA) and triglyceride levels as well as alpha-SMA. Two-dimensional proteomic analysis revealed that the change from the normal diet to the MCD diet affected the expressions of 50 proteins. The most-pronounced changes were observed in the expression of proteins involved in Met metabolism and oxidative stress, most of which were significantly downregulated in NASH model animals. Peroxiredoxin (Prx) is the most interesting among the modulated proteins identified in this study. In particular, cross-regulated Prx1 and Prx6 are likely to participate in cellular defense against the development of hepatitis. Thus, these Prx isoforms may be a useful new marker for early stage steatohepatitis. Moreover, curcumin treatment results in alleviation of the severity of hepatic inflammation in steatohepatitis. Notably, curcumin administration in MCD-fed mice dramatically reduced CYP2E1 as well as Prx1 expression, while upregulating Prx6 expression. These findings suggest that curcumin may have a protective role against MCD fed-induced oxidative stress.

Hepatoprotective Evaluation of Ganoderma lucidum Pharmacopuncture: In vivo Studies of Ethanol-induced Acute Liver Injury

OBJECTIVES

Alcohol abuse is a public issue and one of the major causes of liver disease worldwide. This study was aimed at investigating the protective effect of Ganoderma lucidum pharmacopuncture (GLP) against hepatotoxicity induced by acute ethanol (EtOH) intoxication in rats.

METHODS

Sprague-Dawley (SD) rats were divided into 4 groups of 8 animals each: normal, control, normal saline pharmacopuncture (NP) and GLP groups. The control, NP and GLP groups received ethanol orally. The NP and the GLP groups were treated daily with injections of normal saline and Ganoderma lucidum extract, respectively. The control group received no treatment. The rats in all groups, except the normal group, were intoxicated for 6 hours by oral administration of EtOH (6 g/kg BW). The same volume of distilled water was administered to the rats in the normal group. Two local acupoints were used: Qimen (LR14) and Taechung (LR3). A histopathological analysis was performed, and the liver function and the activities of antioxidant enzymes were assessed.

RESULTS

GLP treatment reduced the histological changes due to acute liver injury induced by EtOH and significantly reduced the increase in the alanine aminotransferase (ALT) enzyme; however, it had an insignificant effect in reducing the increase in aspartate aminotransferase (AST) enzyme. It also significantly ameliorated the superoxide dismutase (SOD) and the catalase (CAT) activities.

CONCLUSION

The present study suggests that GLP treatment is effective in protecting against ethanol-induced acute hepatic injury in SD rats by modulating the activities of ethanol-metabolizing enzymes and by attenuating oxidative stress.

Hepatoprotective effects of Astragalus kahiricus root extract against ethanol-induced liver apoptosis in rats

The hepatoprotective activity of the ethanol extract of Astragalus kahiricus (Fabaceae) roots against ethanol-induced liver apoptosis was evaluated and it showed very promising hepatoprotective actions through different mechanisms. The extract counteracted the ethanol-induced liver enzymes leakage and glutathione depletion. In addition, it demonstrated anti-apoptotic effects against caspase-3 activation and DNA fragmentation that were confirmed by liver histopathological examination. Moreover, the phytochemical study of this extract led to the isolation of four cycloartane-type triterpenes identified as astrasieversianin II (1), astramembrannin II (2), astrasieversianin XIV (3), and cycloastragenol (4). The structures of these isolates were established by HRESI-MS and 1D and 2D NMR experiments. The antimicrobial, antimalarial, and cytotoxic activities of the isolates were further evaluated, but none of them showed any activity.

Endogenous A1 adenosine receptor protects mice from acute ethanol-induced hepatotoxicity

Previous studies have indicated a critical role of adenosine and its receptors in the pathogenesis of liver diseases. The aim of this study was to determine the contribution of A1 adenosine receptor (A1AR) to acute ethanol-induced hepatotoxicity. Wild-type (WT) and A1AR(-/-) mice were intragastrically administered with ethanol (5 g/kg), and hepatic injury was evaluated 6h thereafter. Mice lacking A1AR were more susceptible to ethanol-induced liver damage than WT mice, as evidenced by higher serum transaminase levels and increased extent of histopathological changes. Ethanol induced triglycerides accumulation in the serum and liver, and this accumulation was augmented in A1AR(-/-) mice. Analysis of gene expression in the liver revealed up-regulated mRNA levels of genes related to lipogenesis (including: FAS, SCD1, ACC1, DGAT2, and PPARγ) in A1AR(-/-) mice after ethanol treatment. In addition, lack of A1AR aggravated lipid peroxidation and superoxide dismutase depletion caused by acute ethanol exposure. A subsequent study revealed that, pretreatment with A1AR antagonist DPCPX increases the sensitivity of mice to ethanol-induced liver injury. In conclusion, these results indicated that endogenous A1AR activation protects mice against acute ethanol-induced liver injury by reducing oxidative stress and decreasing lipid accumulation.

Reactive oxygen species and the MEK/ERK pathway are involved in the toxicity of clostridium perfringens α-toxin, a prototype bacterial phospholipase C

Clostridium perfringens, the most broadly distributed pathogen in nature, produces a prototype phospholipase C, also called α-toxin, which plays a key role in the pathogenesis of gas gangrene. α-Toxin causes plasma membrane disruption at high concentrations, but the role of intracellular mediators in its toxicity at low concentrations is unknown. This work demonstrates that α-toxin causes oxidative stress and activates the MEK/ERK pathway in cultured cells and furthermore provides compelling evidence that O(2)(-.), hydrogen peroxide, and the OH(.) radical are involved in its cytotoxic and myotoxic effects. The data show that antioxidants and MEK1 inhibitors reduce the cytotoxic and myotoxic effects of α-toxin and demonstrate that edaravone, a clinically used hydroxyl radical trap, reduces the myonecrosis and the mortality caused by an experimental infection with C. perfringens in a murine model of gas gangrene. This knowledge provides new insights for the development of novel therapies to reduce tissue damage during clostridial myonecrosis.

Effect of Emilia sonchifolia (Linn.)DC on alcohol-induced oxidative stress in pancreas of male albino rats

OBJECTIVE

To explore the efficacy of n-hexane extract of Emilia sonchifolia (E. sonchifobia) against ethanol induced pancreatic dysfunction in the young Wistar albino rats.

METHODS

The rats were divided into four groups. Control rats in group received distilled water orally, group received oral administration of 20% (w/v) ethanol dissolved in drinking water, group received oral administration of 20% (w/v) ethanol in distilled water+n-hexane extract of E. sonchifolia (250 mg/kg body weight), and group received oral administration of n-hexane extract of E. sonchifolia (250 mg/kg body weight) alone. Liver marker enzymes aspartate aminotransferase (AST), alanine aminotransferase (ALT), pancreatic enzymatic antioxidants superoxide dismutase, lipid peroxidation, catalase, glutathione peroxidase, non-enzymatic antioxidants glutathione and vitamin C were measured and compared.

RESULTS

Administration of 20% ethanol for 16 weeks significantly increased the liver marker enzymes AST, ALT(P<0.05), reduced the pancreatic enzymatic antioxidants superoxide dismutase, lipid peroxidation, catalase, glutathione peroxidase, glutathione and vitamin C(P<0.05). Histopathological examination showed that the ethanol provoked the oxidative stress which was demonstrated as pancreatic necrosis and oedema. Simultaneous administration of n-hexane extract of E. sonchifolia (250 mg/kg body weight) protected the pancreas against the damage induced by ethanol which was confirmed by the histopathological studies and the normalization of biochemical parameters.

CONCLUSIONS

Thus n-hexane extract of E. sonchifolia shows a promise in therapeutic use in alcohol induced oxidative stress.

Increased mitochondrial matrix-directed superoxide production by fatty acid hydroperoxides in skeletal muscle mitochondria

Previous studies have shown that muscle atrophy is associated with mitochondrial dysfunction and an increased rate of mitochondrial reactive oxygen species production. We recently demonstrated that fatty acid hydroperoxides (FA-OOHs) are significantly elevated in mitochondria isolated from atrophied muscles. The purpose of this study was to determine whether FA-OOHs can alter skeletal muscle mitochondrial function. We found that FA-OOHs (at low-micromolar concentrations) induce mitochondrial dysfunction assessed by a decrease in the rate of ATP production, oxygen consumption, and activity of respiratory chain complexes I and III. Using methods to distinguish superoxide release toward the matrix and toward the intermembrane space, we demonstrate that FA-OOHs significantly elevate oxidative stress in the mitochondrial matrix (and not the intermembrane space), with complex I as the major site of superoxide production (most probably from a site upstream of the ubiquinone binding site but downstream from the flavin binding site-the iron sulfur clusters). Our results are the first to indicate that FA-OOHs are important modulators of mitochondrial function and oxidative stress in skeletal muscle mitochondria and may play an important role in muscle atrophies that are associated with increased generation of FA-OOHs, e.g., denervation-induced muscle atrophy.

Protective effect of some vitamins against the toxic action of ethanol on liver regeneration induced by partial hepatectomy in rats

AIM

To investigate the effects of vitamins (A, C and E) on liver injury induced by ethanol administration during liver regeneration in rats.

METHODS

Male Wistar rats subjected to 70% partial hepatectomy were divided into five groups (groups 1-5). During the experiment, animals of Group 1 drank only water. The other four groups (2-5) drank 30 mL of ethanol/L of water. Group 3 additionally received vitamin A, those of group 4 vitamin C and those of group 5 received vitamin E. Subsequently serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin and bilirubin were measured colorimetrically. Lipid peroxidation (thiobarbituric-acid reactive substances, TBARS) both in plasma and liver was measured, as well as liver mass gain assessment and total DNA.

RESULTS

Compared with sham group, serum AST and ALT increased significantly under ethanol treatment (43% and 93%, respectively, with P < 0.05). Vitamin C and vitamin E treatment attenuated the ethanol-induced increases in ALT and AST activity. Ethanol treatment also decreased serum albumin concentration compared to sham group (3.1 +/- 0.4 g/dL vs 4.5 +/- 0.2 g/dL; P < 0.05). During liver regeneration vitamins C and E significantly ameliorated liver injury for ethanol administration in hepatic lipid peroxidation (4.92 nmol/mg and 4.25 nmol/mg vs 14.78 nmol/mg, respectively, with P < 0.05). In association with hepatic injury, ethanol administration caused a significant increase in both hepatic and plasma lipid peroxidation. Vitamins (C and E) treatment attenuated hepatic and plasma lipid peroxidation.

CONCLUSION

Vitamins C and E protect against liver injury and dysfunction, attenuate lipid peroxidation, and thus appear to be significantly more effective than vitamin A against ethanol-mediated toxic effects during liver regeneration.

Toxicity of fatty acid hydroperoxides towards Yarrowia lipolytica: Implication of their membrane fluidizing action

Linoleic acid hydroperoxide (HPOD), substrate of hydroperoxide lyase, an enzyme of the lipoxygenase pathway, can be transformed into many aromatic compounds, the so-called "green notes". The presence of linoleic acid hydroperoxide in the culture medium of Yarrowia lipolytica, the yeast expressing the cloned hydroperoxide lyase of green bell pepper, undoubtedly exerted an inhibition on the growth and a toxic effect with 90% of yeast cells died after 120 min of exposition in 100 mM HPOD solution. The increase in cell membrane fluidity evaluated by measuring fluorescence generalized polarization with the increasing concentration of HPOD in the medium confirmed the fluidizing action of HPOD on yeast membrane. In addition, we determined by infrared spectroscopy measurement that this compound rapidly diffused into model phospholipids [1, 2-Dimyristoyl-D54-sn-Glycero-3-Phosphocholine (DMPC-D54)] bilayer, modifying their general physical state and their phase transition. In the presence of various concentrations of HPOD, the phase transition of DMPC-D54 occurred with an increase of both the corresponding wave number shift and the temperature range but the phase transition temperature was not modified. These results show that the toxic effects of HPOD on the yeast Yarrowia lipolytica may be initially linked to a strong interaction of this compound with the cell membrane phospholipids and components.

L-Buthionine (S,R) sulfoximine depletes hepatic glutathione but protects against ethanol-induced liver injury

BACKGROUND

L-Buthionine (S,R) sulfoximine (BSO) is an inhibitor of glutathione biosynthesis and has been used as an effective means of depleting glutathione from cells and tissues. Here we investigated whether treatment with BSO enhanced ethanol-induced liver injury in mice.

METHODS

Female C57Bl/6 mice were pair fed with control and ethanol-containing liquid diets in which ethanol was 29.2% of total calories. During the final 7 days of pair feeding, groups of control-fed and ethanol-fed mice were given 0, 5 or 7.6 mM BSO in the liquid diets.

RESULTS

Compared with controls, ethanol given alone decreased total liver glutathione. This effect was exacerbated in mice given ethanol with 7.6 mM BSO, causing a 72% decline in hepatic glutathione. While ethanol alone caused no decrease in mitochondrial glutathione, inclusion of 7.6 mM BSO caused a 2-fold decline compared with untreated controls. L-Buthionine (S,R) sulfoximine did not affect ethanol consumption, but serum ethanol levels in BSO-treated mice were nearly 6-fold lower than in mice given ethanol alone. The latter decline in serum ethanol was associated with a significant elevation in the specific activities of cytochrome P450 2E1 and alcohol dehydrogenase in livers of BSO-treated animals. Ethanol consumption caused a 3.5-fold elevation in serum alanine aminotransferase levels but the enzyme fell to control levels when BSO was included in the diet. L-Buthionine (S,R) sulfoximine administration also attenuated ethanol-induced steatosis, prevented the leakage of lysosomal cathepsins into the cytosol, and prevented the ethanol-elicited decline in proteasome activity.

CONCLUSIONS

L-Buthionine (S,R) sulfoximine, administered with ethanol, significantly depleted hepatic glutathione, compared with controls. However, despite the decrease in hepatic antioxidant levels, liver injury by ethanol was alleviated, due, in part, to a BSO-elicited acceleration of ethanol metabolism.

Silymarin protects against acute ethanol-induced hepatotoxicity in mice

BACKGROUND

Accumulated evidence has demonstrated that both oxidative stress and abnormal cytokine production, especially tumor necrosis factor-alpha (TNF), play important etiological roles in the pathogenesis of alcoholic liver disease (ALD). Agents that have both antioxidant and anti-inflammation properties, particularly anti-TNF production, represent promising therapeutic interventions for ALD. We investigated the effects and the possible mechanism(s) of silymarin on liver injury induced by acute ethanol (EtOH) administration.

METHODS

Nine-week-old mice were divided into 4 groups, control, silymarin treatment, EtOH treatment, and silymarin/EtOH treatment, with 6 mice in each group. Because control and silymarin values were virtually identical, only control treatment is shown for ease of viewing. Ethanol-treated mice received EtOH [5 g/kg body weight (BW)] by gavage every 12 hours for a total of 3 doses. Control mice received an isocalorical maltose solution. In the silymarin/EtOH group, silymarin was dissolved in the EtOH and gavaged simultaneously with EtOH at a dose of 200 mg/kg BW. At 4 hours after the last dosing, the mice were anesthetized and subsequent serum alanine aminotransferase (ALT) level, hepatic lipid peroxidation, enzymatic activity of hepatic cytochrome P450 2E1, hepatic TNF-alpha, and glutathione (GSH) levels were measured. Histopathological change was assessed by hematoxylin and eosin staining.

RESULTS

Acute EtOH administration caused prominent hepatic microvesicular steatosis with mild necrosis and an elevation of serum ALT activity, induced a significant decrease in hepatic GSH in conjunction with enhanced lipid peroxidation, and increased hepatic TNF production. Supplementation with a standardized silymarin attenuated these adverse changes induced by acute EtOH administration.

CONCLUSIONS

Silymarin protects against the liver injury caused by acute EtOH administration. In view of its nontoxic nature, it may be developed as an effective therapeutic agent for alcohol-induced liver disease by its antioxidative stress and anti-inflammatory features.

Mitochondrially targeted vitamin E and vitamin E mitigate ethanol-mediated effects on cerebellar granule cell antioxidant defense systems

Ethanol (EtOH) disrupts the structure and function of the developing nervous system, sometimes leading to birth defects associated with fetal alcohol syndrome (FAS). Animal FAS models indicate that cellular membrane peroxidation, intracellular oxidant accumulation, and suppression of endogenous antioxidant enzymes contribute to the toxic effects of EtOH. Mitochondrially targeted vitamin E (MitoVit E), a chemically engineered form of vitamin E (VE) designed to accumulate in the mitochondria, has been shown to inhibit intracellular oxidant accumulation and cell death more effectively than VE. In previous investigations, we have shown that, in vivo, VE reduces neuronal death in the developing cerebellum of EtOH-exposed animals, and, in vitro, VE prevents apoptotic and necrotic death of EtOH-exposed cerebellar granule cells (CGCs). The present investigation shows that, in a FAS CGC model, 1 nM MitoVit E renders significant neuroprotection against EtOH concentrations as high as 1600 mg/dL. The present study also demonstrates that, in this same model, MitoVit E mitigates EtOH-induced accumulation of intracellular oxidants and counteracts suppression of glutathione peroxidase/glutathione reductase (GSH-Px/GSSG-R) functions, protein expression of gamma-glutamylcysteine synthetase (gamma-GCS), and total cellular glutathione (GSH) levels. In the presence and absence of EtOH, VE amplifies the protein expression levels of gamma-GCS, an enzyme that performs the rate-limiting step for GSH synthesis, and total GSH levels. These results suggest that MitoVit E and VE ameliorate EtOH toxicity through non-oxidant mechanisms-modulations of endogenous cellular proteins-and antioxidant means.

Bax interacts with the voltage-dependent anion channel and mediates ethanol-induced apoptosis in rat hepatocytes

Acute ethanol exposure induces oxidative stress and apoptosis in primary rat hepatocytes. Previous data indicate that the mitochondrial permeability transition (MPT) is essential for ethanol-induced apoptosis. However, the mechanism by which ethanol induces the MPT remains unclear. In this study, we investigated the role of Bax, a proapoptotic Bcl-2 family protein, in acute ethanol-induced hepatocyte apoptosis. We found that Bax translocates from the cytosol to mitochondria before mitochondrial cytochrome c release. Bax translocation was oxidative stress dependent. Mitochondrial Bax formed a protein complex with the mitochondrial voltage-dependent anion channel (VDAC). Prevention of Bax-VDAC interactions by a microinjection of anti-VDAC antibody effectively prevented hepatocyte apoptosis by ethanol. In conclusion, these data suggest that Bax translocation from the cytosol to mitochondria leads to the subsequent formation of a Bax-VDAC complex that plays a crucial role in acute ethanol-induced hepatocyte apoptosis.

S-Adenosylmethionine Protects against Acetaminophen-Induced Hepatotoxicity in Mice

An overdose of acetaminophen (APAP) is the most frequent cause of fulminant liver failure in the United States. Increasing evidence demonstrates that oxidative stress plays an important etiologic role in APAP-induced liver injury. S-Adenosylmethionine (SAMe) is a key intermediate in the hepatic trans-sulfuration pathway and serves as a precursor for glutathione (GSH) as well as the methyl donor in most transmethylation reactions. In the present study, we investigated effects of SAMe on liver injury induced by APAP administration in male C57BL/6 mice. Two related studies were performed. In the first experiment, SAMe (1g/kg BW) was injected intraperitoneally 4 h before APAP (600 mg/kg BW) administration. In the second experiment, SAMe was injected intraperitoneally 1 h after APAP administration. Our results showed that APAP administration induced changes typical of confluent centrilobular necrosis by histological examination and a marked elevation in serum alanine aminotransferase (ALT) activity. APAP administration induced significant decreases in both hepatic and blood SAMe concentrations. In addition, APAP decreased intracellular (both cytosolic and mitochondrial) GSH concentrations along with increased lipid peroxidation in conjunction with mitochondrial dysfunction as documented by Ca2+-induced mitochondrial permeability transition. SAMe treatment (both before and after APAP) significantly attenuated the liver injury. Exogenous SAMe prevented the decrease in liver and blood SAMe concentrations. Moreover, SAMe treatment attenuated both cytosolic and mitochondrial GSH depletion as well as mitochondrial dysfunction. We conclude that SAMe at least in part protects the liver from APAP-induced injury by preventing intracellular GSH depletion and mitochondrial dysfunction.

S-adenosylmethionine (SAMe) protects against acute alcohol induced hepatotoxicity in mice

Although S-Adenosylmethionine (SAMe) has beneficial effects in many hepatic disorders, the effects of SAMe on acute alcohol-induced liver injury are unknown. In the present study, we investigated effects of SAMe on liver injury in mice induced by acute alcohol administration. Male C57BL/6 mice received ethanol (5 g/kg BW) by gavage every 12 hrs for a total of 3 doses. SAMe (5 mg/kg BW) was administrated i.p. once a day for three days before ethanol administration. Subsequent serum ALT level, hepatic lipid peroxidation, enzymatic activity of CYP2E1 and hepatic mitochondrial glutathione levels were measured colorimetrically. Intracellular SAMe concentration was measured by high-performance liquid chromatography (HPLC). Histopathological changes were assessed by H&E staining. Our results showed that acute ethanol administration caused prominent microvesicular steatosis with mild necrosis and an elevation of serum ALT activity. SAMe treatment significantly attenuated the liver injury. In association with the hepatocyte injury, acute alcohol administration induced significant decreases in both hepatic SAMe and mitochondrial GSH levels along with enhanced lipid peroxidation. SAMe treatment attenuated hepatic SAMe and mitochondrial GSH depletion and lipid peroxidation following acute alcohol exposure. These results demonstrate that SAMe protects against the liver injury and attenuates the mitochondrial GSH depletion caused by acute alcohol administration. SAMe may prove to be an effective therapeutic agent in many toxin-induced liver injuries including those induced by alcohol.

Binge ethanol exposure increases liver injury in obese rats

BACKGROUND & AIMS

The objective of this study was to address the hepatic effects of acute alcohol consumption in obesity by simulating an alcohol binge in genetically obese fa/fa rats compared with lean Fa/? rats.

METHODS

Ethanol 4 g/kg or saline was administered by gavage every 12 hours for 3 days.

RESULTS

Plasma alcohol levels were similar in both groups. Binge ethanol exposure caused liver injury in obese fa/fa but not in lean Fa/? rats, as assessed by alanine aminotransferase and H&E staining. Obesity impaired the antioxidant defense because basal levels of glutathione, glutamate cysteine ligase modulatory subunit, catalase, glutathione reductase, and superoxide dismutase were lower in fa/fa compared with Fa/? rats; the ethanol binge further decreased these antioxidants in fa/fa rats and also decreased glutathione peroxidase activity. Nonesterified fatty acids and lipid peroxidation were increased after ethanol treatment in fa/fa rats. Cytochrome P450 2E1 was down-regulated in fa/fa compared with Fa/? rats; however, the ethanol binge increased cytochrome P450 2E1 in both genotypes. Adenosine triphosphate decreased and uncoupling protein 2 increased in fa/fa rats treated with ethanol. 3-Nitrotyrosine protein adducts were detected only in fa/fa rats treated with ethanol, and this was accompanied by an induction of inducible nitric oxide synthase. Ethanol binge increased caspase-3 and caspase-8 activity, the expression of Fas ligand, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling in fa/fa rats.

CONCLUSIONS

These data indicate that binge drinking increases apoptosis and liver injury in obese rats more than in lean controls and suggest that the injury may involve oxidative and nitrosative damage.

Alcohol-induced liver injury in mice lacking Cu, Zn-superoxide dismutase

Because alcoholic liver disease has been linked to oxidative stress, we investigated the effect of a compromised antioxidant defense system, Cu, Zn-superoxide dismutase (Sod1) deficiency, on alcohol-induced liver injury. C57BL/129SV wild-type (Sod1(+/+)) and Sod1 knockout (Sod1(-/-)) mice were fed dextrose or ethanol (10% of total calories) liquid diets for 3 weeks. Histologic evaluation of liver specimens of Sod1(-/-) mice fed ethanol showed the development of liver injury ranging from mild to extensive centrilobular necrosis and inflammation. Sod1(+/+) mice fed ethanol showed mild steatosis; both Sod1(+/+) and Sod1(-/-) mice fed the dextrose diet had normal histology. Alanine transaminase levels were significantly elevated only in Sod1(-/-) mice fed ethanol. Cytochrome P450 2E1 (CYP2e1) activity was elevated about 2-fold by ethanol in Sod1(+/+) and Sod1(-/-) mice. Ethanol consumption increased levels of protein carbonyls and lipid peroxidation aldehydic products in the liver of Sod1(-/-) mice. Hepatic adenosine triphosphate (ATP) content was reduced dramatically in Sod1(-/-) mice fed ethanol in association with a decrease in the mitochondrial reduced glutathione (GSH) level and activity of MnSOD. Immunohistochemical determination of 3-nitrotyrosine (3NT) residues in liver sections of the Sod1 knockout mice treated with ethanol showed a significant increase of 3NT staining in the centrilobular areas. In conclusion, a rather moderate ethanol consumption promoted oxidative stress in Sod1(-/-) mice, with increased formation of peroxynitrite, protein carbonyls, and lipid peroxidation and decreased mitochondrial GSH and MnSOD. We speculate that the increased oxidative stress causes mitochondrial damage and reduction of ATP content, leading to alcoholic liver injury. This model may be useful in further mechanistic studies on alcohol-induced liver injury.

S-Adenosyl-L-methionine and mitochondrial reduced glutathione depletion in alcoholic liver disease

The pathogenesis of alcohol-induced liver disease is not well understood, and many factors have been described to contribute to the progressive loss of liver functions, including the overgeneration of reactive oxygen species. Mitochondria are specific targets of the toxic effects of ethanol, reflected in the loss of phosphorylative oxidation and defective ATP generation, which underlie one of the hallmarks of the hepatic alterations induced by chronic alcohol intake. Mitochondrial reduced glutathione (GSH), whose primary function is to maintain a competitive functional organelle, becomes depleted by alcohol intake. Furthermore, GSH depletion in hepatocyte mitochondria has been revealed as an important mechanism in the sensitization of liver to alcohol-induced injury. This depletion of the mitochondrial GSH level is determined by an impaired transport of GSH from the cytosol into the mitochondrial matrix owing to a partial inactivation of mitochondrial GSH carrier. The loss of function of this specific mitochondrial transporter is due to the alterations in the physicochemical properties of the inner mitochondrial membrane caused by alcohol. Because of the primary defect in the transport of cytosolic GSH into mitochondria, GSH precursors are inefficient in replenishing the levels of mitochondrial GSH despite significant increase in cytosolic GSH. Supplementation of S-adenosyl-L-methionine (SAM) to rats fed alcohol chronically has been shown to replete the mitochondrial GSH levels because of normalization of the microviscosity of the mitochondrial inner membrane. Because of the instrumental role of GSH in mitochondria in hepatocyte survival against inflammatory cytokines, its repletion by SAM feeding may underlie the potential therapeutic use of this hepatoprotective agent in the treatment of alcohol-induced liver injury.

Acetaminophen-induced suppression of hepatic AdoMet synthetase activity is attenuated by prodrugs of L-cysteine

Administration of acetaminophen (ACP, 400 mg/kg, i.p.) to fasted, male Swiss-Webster mice caused a rapid 90% decrease in total hepatic glutathione (GSH) and a 58% decrease in mitochondrial GSH by 2 h post ACP. This was followed by a time-dependent decrease (72%) in hepatic AdoMet synthetase activity and rise in plasma ALT levels (>10000 U/l) at 24 h post ACP treatment. AdoMet synthetase activity was maintained at 82, 78 and 60% of controls, respectively, by the cysteine prodrugs PTCA, CySSME and NAC. Total hepatic and mitochondrial GSH levels were also protected from severe ACP-induced depletion by CySSME and MTCA. These results suggest that the maintenance of GSH homeostasis by cysteine prodrugs can protect mouse hepatic AdoMet synthetase, a sulfhydryl enzyme whose integrity is dependent on GSH, as well as the liver itself from the consequences of oxidative stress elicited by toxic metabolites of xenobiotics.

Role of mitochondria in alcoholic liver injury

Oxidative stress and oxygen-derived free radicals are well known to play an important role in the pathogenesis of ethanol-associated liver injury. Active oxidants produced during ethanol metabolism induce mitochondrial membrane depolarization and permeability changes in cultured hepatocytes. These mitochondrial alterations (loss of DeltaPsim and mitochondrial permeability transition [MPT]) are now recognized as a key step in apoptosis. In recent studies, including ours, the MPT has been identified as a key step for the induction of mitochondrial cytochrome c release and caspase activation by ethanol. In addition, chronic and/or acute ethanol modulates intracellular, especially mitochondrial, antioxidant levels, leading to the increased susceptibility to alcoholic liver injury induced by several apoptotic stimuli. In this review, we address the mechanism of mitochondrial alterations and liver injury induced by ethanol.

Metallothionein protection against alcoholic liver injury through inhibition of oxidative stress

Antioxidants are likely potential pharmaceutical agents for the treatment of alcoholic liver disease. Metallothionein (MT) is a cysteine-rich protein and functions as an antioxidant. This study was designed to determine whether MT confers resistance to acute alcohol-induced hepatotoxicity and to explore the mechanistic link between oxidative stress and alcoholic liver injury. MT-overexpressing transgenic and wild-type mice were administrated three gastric doses of alcohol at 5 g/kg. Liver injury, oxidative stress, and ethanol metabolism-associated changes were determined. Acute ethanol administration in the wild-type mice caused prominent microvesicular steatosis, along with necrosis and elevation of serum alanine aminotransferase. Ultrastructural changes of the hepatocytes include glycogen and fat accumulation, organelle abnormality, and focal cytoplasmic degeneration. This acute alcohol hepatotoxicity was significantly inhibited in the MT-transgenic mice. Furthermore, ethanol treatment decreased hepatic-reduced glutathione, but increased oxidized glutathione along with lipid peroxidation, protein oxidation, and superoxide generation in the wild-type mice. This hepatic oxidative stress was significantly suppressed in the MT-transgenic mice. However, MT did not affect the ethanol metabolism-associated decrease in NAD(+)/NADH ratio or increase in cytochrome P450 2E1. In conclusion, MT is an effective agent in cytoprotection against alcohol-induced liver injury, and hepatic protection by MT is likely through inhibition of alcohol-induced oxidative stress.

Toxicity by pyruvate in HepG2 cells depleted of glutathione: role of mitochondria

Several studies have shown that pyruvate can scavenge H(2)O(2) and protect from H(2)O(2)-mediated cell injury. Mitochondria are critical participants in the control of apoptotic and necrotic cell death. Mitochondrial GSH plays an important role in the maintenance of cell functions and viability by metabolism of oxygen free radicals generated by the respiratory chain. Since loss of GSH, especially mitochondrial GSH, is associated with increased production of reactive oxygen species and cell toxicity, the ability of pyruvate to protect against these actions was evaluated. Adding pyruvate to HepG2 cells depleted of GSH by treatment with l-buthionine sulfoximine (BSO) surprisingly caused loss of viability after 24 and 48 h of incubation. Anoxia, treatment with antioxidants, and infection with cytosolic catalase, and interestingly, catalase expressed in the mitochondrial compartment were able to rescue the HepG2 cells from this pyruvate plus BSO injury, suggesting a key role for H(2)O(2), and lipid peroxides as mediators in the cytotoxicity. This toxicity and cell death observed was linked to damage to the mitochondria as evidenced by the increased lipid peroxidation in total homogenate and mitochondrial fraction, loss of mitochondrial membrane potential, and a decrease in protein-sulfhydryl groups. The type of cell death observed under these conditions was a mixture of apoptosis and necrosis. These results suggest that the protective ability of pyruvate against oxidant damage requires a functional GSH pool, especially in the mitochondrial compartment, and that in the absence of GSH, pyruvate increases cell injury by damaging the mitochondria, presumably as a consequence of enhanced electron flow and reactive oxygen production by the respiratory chain.

The role of mitochondrial injury in bromobenzene and furosemide induced hepatotoxicity

Bromobenzene (BB) and furosemide (FS) are two hepatotoxicants whose bioactivation to reactive intermediates is crucial to the development of liver injury. However, the events which lead to hepatocellular toxicity following metabolite formation and covalent binding to cellular macromolecules remain unknown. The present study was undertaken to investigate the effect of administered BB and FS on mitochondrial total glutathione (GSH+GSSG, henceforth referred to as glutathione) content and respiratory function as potential initiating mechanisms of the hepatotoxicity of these compounds in the mouse. Bromobenzene (2 g/kg i.p.) significantly decreased mitochondrial glutathione to 48% of control at 3 h post administration, and to 41% at 4 h. This decrease in mitochondrial glutathione was subsequent to a significant decrease in cytosolic glutathione to 64 and 28% of control at 1 and 2 h, respectively. Oxygen consumption supported by complex I (glutamate-supported) of the respiratory chain was not inhibited by BB until 4 h, where state 3 (active) respiration was reduced to 16% of control. This resulted in a decreased respiratory control ratio (RCR) for complex I-supported respiration. Complex II (succinate)-supported state 3 and state 4 respiration were unaffected by BB until 4 h, at which time they were reduced to 57 and 48% of control, respectively. However, the similar reductions in state 3 and state 4 respiratory rates did not alter the corresponding RCR for complex II. Overt hepatic injury was detected at 4 h, with plasma alanine aminotransferase (ALT) activity increasing significantly at this time point. In contrast to the effects of BB, FS administration (400 mg/kg i.p.) did not alter mitochondrial or cytosolic glutathione, and had no effect on respiration supported by complex I or II for up to 5 h following dosing. However, ALT activity was significantly increased 5 h following FS administration. These results suggest that inhibition of mitochondrial respiratory function coinciding with a decrease in mitochondrial glutathione content may be crucial to the initiation of BB-induced hepatotoxicity, while such events are not required for the initiation of FS-induced hepatotoxicity.

Protective effect of Phyllanthus fraternus against carbon tetrachloride-induced mitochondrial dysfunction

The effect of carbon tetrachloride administration on liver mitochondrial function and the protective effect of an aqueous extract of Phyllanthus fraternus were studied in rats. The following changes were observed in mitochondria due to the administration of carbon tetrachloride. 1) A decrease in the rate of respiration, respiratory control ratio and P/O ratio using glutamate and malate or succinate as substrates. 2) A decrease in the activities of NADH dehydrogenase (35%), succinate dehydrogenase (76%) and cytochrome c oxidase (51%). The rate of electron transfer through site I, site II and site III was studied independently and found to be significantly decreased. 3) A decrease in the content of cytochrome aa3 (34%). 4) A significant decrease in the levels of phospholipids particularly cardiolipin and a significant increase in the lipid peroxide level was observed. The carbon tetrachloride induced toxicity may be partly due to the lipid peroxidation and partly due to the effect on protein synthesis. Administration of rats with an aqueous extract of P. fraternus prior to carbon tetrachloride administration showed significant protection on the carbon tetrachloride induced mitochondrial dysfunction on all the parameters studied.

The effect of ethanol and acetaldehyde on microsomal and mitochondrial membrane fatty acid profiles in cultured rat astroglia

It has been shown that free radical damage may be involved in ethanol-induced cytotoxicity in cultured neural cells. Since changes in oxidative metabolism and the resulting lipid peroxidation readily modify biological membranes and alter cell functions we studied the effect of ethanol and its metabolite acetaldehyde on rat astroglial fatty acids profiles in the most common lipid classes of mitochondrial and microsomal membranes, i.e. phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Rat astroglial cells were grown for 1 week in the presence of 50 m M or 100 m M ethanol. To examine acetaldehyde effects we used a 4-day co-culture model consisting of astroglial cells and alcohol dehydrogenase-transfected Chinese hamster ovary (CHO) cells. Acetaldehyde produced by these cells reached 172 mu M and 265 mu M, respectively, for ethanol concentrations of 10 and 20 m M. Mitochondrial and microsomal membranes were prepared by differential centrifugation, phosphatidylcholine and phosphatidylethanolamine were separated using thin layer chromatography and fatty acid quantitation was performed by GLC. Neither ethanol nor acetaldehyde changed the mitochondrial phosphatidylcholine or phosphatidylethanolamine profiles of total saturated, mono-unsaturated or polyunsaturated fatty acids. However, some significant alterations in particular fatty acids appeared especially after acetaldehyde but also after the highest ethanol dose. In microsomal phosphatidylcholine monounsaturated fatty acids were significantly increased after both, ethanol and acetaldehyde exposure. Among polyunsaturated fatty acids, arachidonic acid was found to be especially affected by both ethanol and acetaldehyde. Similar decreases were observed in adrenic, docosapentaenoic and docosahexaenoic acids in the groups treated with ethanol. In microsomal phosphatidylethanolamine, ethanol and acetaldehyde decreased monounsaturated and some polyunsaturated fatty acids. These data support the role of peroxidative processes in cultured rat astroglia exposed to ethanol and point to the role of acetaldehyde in this mechanism.

Oxidative stress and mitochondrial damage precedes gastric mucosal cell death induced by ethanol administration

Although it has been speculated that active oxidants and mitochondrial membrane damages play roles in ethanol-induced gastric mucosal damages, its detail remains unknown. The present study was designed to investigate whether ethanol induces oxidative stress and mitochondrial permeability transition (MPT) before cell death of gastric mucosal cells. Rat gastric mucosal cells (RGM-1) were kept in serum-free Dulbecco's modified Eagle's medium before addition of various concentrations of ethanol. Nuclear morphological aftemations and membrane barrier dysfunction of RGM-1 cells were assessed by staining with Hoechst 33342 and propidium iodide, respectively. To assess the contribution of oxygen-derived free radicals and intracellular glutathione, scavenger of hydrogen peroxide and the hydroxyl radical, N,N-dimethylthiourea, glutathione precursor, N-acetyl-L-cysteine, and an inhibitor of alcohol dehydrogenase, 4-methylpyrazole were added before treatment with ethanol. To investigate MPT, calcein and tetramethylrhodamine methyl ester were loaded before addition of ethanol, and the changes of fluorescence intensity were monitored using a laser scanning confocal microscope. Ethanol (>5% v/v) dose-dependently increased the number of propidium iodide-positive cells, suggesting a diminished barrier function of cell membrane. After addition of ethanol, mitochondria were filled quickly with calcein indicating MPT, which was accompanied by mitochondrial depolarization, as shown by loss of tetramethylrodamine methyl ester before cell death. Ethanol-induced cell death was significantly attenuated by simultaneous incubation with either N,N-dimethylthiourea or N-acetyl-L-cysteine, suggesting the importance of intracellular redox states in inducing cellular damage, whereas such change was not attenuated by 4-methylpyrazole. Present results suggest that ethanol treatment induces intracellular oxidative stress and produces MPT and mitochondrial depolarization, which are preceding cell death in gastric mucosal cells. Intracellular antioxidants, such as glutathione, may have a significant protective action against ethanol in gastric mucosal cells.

Pathogenesis of alcoholic liver disease with particular emphasis on oxidative stress

Oxidative stress is well recognized to be a key step in the pathogenesis of ethanol-associated liver injury. Ethanol administration induces an increase in lipid peroxidation either by enhancing the production of oxygen reactive species and/or by decreasing the level of endogenous antioxidants. Numerous experimental studies have emphasized the role of the ethanol-inducible cytochrome P450 in the microsomes and the molybdo-flavoenzyme xanthine oxidase in the cytosol. This review shows the putative role of ethanol-induced disturbances in iron metabolism in relation to iron as a pro-oxidant factor. Ethanol administration also affects the mitochondrial free radical generation. Many previous studies suggest a role for active oxygens in ethanol-induced mitochondrial dysfunction in hepatocytes. Recent studies in our laboratory in the Department of Internal Medicine, Keio University, using a confocal laser scanning microscopic system strongly suggest that active oxidants generated during ethanol metabolism produce mitochondrial membrane permeability transition in isolated and cultured hepatocytes. In addition, acetaldehyde, ethanol consumption-associated endotoxaemia and subsequent release of inflammatory mediators may cause hepatocyte injury via both oxyradical-dependent and -independent mechanisms. These cytotoxic processes may lead to lethal hepatocyte injury. Investigations further implicate the endogenous glutathione-glutathione peroxidase system and catalase as important antioxidants and cytoprotective machinery in the hepatocytes exposed to ethanol.

Ethanol-induced apoptosis and oxidative stress in hepatocytes

This short review focuses on ethanol-induced oxidative stress and hepatocyte apoptosis. Apoptosis is increasingly recognized as a fundamental biological process that impacts on an early development, maturation, and acquisition of disease states of multicellular organisms. Although the occurrence of apoptosis has been identified for many decades, relatively recent acceptance of this principle is evidenced by remarkable increases in special conferences and presentations on this topic as well as its rapidly expanding volume of scientific literature. Oxidative stress is well recognized to be a key step in the pathogenesis of ethanol-associated liver injury. Ethanol administration induces an increase in lipid peroxidation either by enhancing the production of oxygen reactive species and/or by decreasing the level of endogenous antioxidants. Studies in our laboratory using a confocal laser scanning microscopic system strongly suggest that agents which inhibit ethanol-induced oxidative stress effectively attenuate hepatocyte death, i.e., apoptosis and necrosis. In addition, our investigations demonstrated that inhibitors of intracellular antioxidants exaggerate ethanol-associated hepatocyte apoptosis. Although the detailed mechanism still remains unknown, it is conceivable that an oxidant-dependent mechanism is largely involved in the process for ethanol-induced hepatocyte apoptosis.

Impairment of mitochondrial respiration and electron transport chain enzymes during cocaine-induced hepatic injury

Morphological and biochemical changes in mitochondrial have been reported early in the course of cocaine-induced hepatotoxicity. This study was designed to examine the effects of repeated cocaine exposure in vivo on mitochondrial respiration, activities of respiratory chain enzymes, and lipid peroxide measures in liver. Male Sprague-Dawley rats were exposed to cocaine (5 i.p. injections of 25 mg/kg; 3-day period). Blood and liver samples were taken, and hepatic mitochondria were isolated by differential centrifugation. The cocaine-treated rats developed oxidative stress in hepatic mitochondria as evidenced by a significant increase in malonaldialdehyde (MDA; 52%; p < 0.0001) and a decreased glutathione (GSH; 22%; p < 0.0003). Blood aspartate aminotransferase (AST) and glutathione s-transferase (GST) levels in cocaine groups were significantly elevated (2.6 and 3.2 fold, respectively; p < 0.0001 for both). Cocaine caused a decrease in state-3 respiration and respiratory control ratio (RCR) ratio when exposed to site I and II substrates; these changes were parallelled by a decrease in complex I (22%; p < 0.003), succinate cytochrome c reductase (27%; p < 0.004), and complex IV (24%; p < 0.003). In conclusion, functional abnormalities of hepatic mitochondria accompany lipid peroxidation caused by cocaine, supporting the hypothesis that the mitochondria is one of the major intracellular targets of cocaine hepatotoxicity.

Feeding S-adenosyl-L-methionine attenuates both ethanol-induced depletion of mitochondrial glutathione and mitochondrial dysfunction in periportal and perivenous rat hepatocytes

Mitochondrial glutathione plays an important role in maintaining a functionally competent organelle. Previous studies have shown that ethanol feeding selectively depletes the mitochondrial glutathione pool, more predominantly in mitochondria from perivenous hepatocytes. Because S-adenosyl-L-methionine (SAM) is a glutathione precursor and maintains the structure and function of biological membranes, the purpose of the present study was to determine the effects of SAM on glutathione and function of perivenous (PV) and periportal (PP) mitochondria from chronic ethanol-fed rats. SAM administration resulted in a significant increase in the basal cytosol and mitochondrial glutathione in both PP and PV cells from both pair-fed or ethanol-fed groups. When hepatocytes from ethanol-fed rats supplemented with SAM were incubated with methionine plus serine or N-acetylcysteine, mitochondrial glutathione increased in parallel with cytosol, an effect not observed in cells from ethanol-fed rats without SAM. Feeding equimolar N-acetylcysteine raised cytosol glutathione but did not prevent the mitochondrial glutathione defect. In addition, SAM feeding resulted in significant preservation of cellular adenosine triphosphate (ATP) levels (23% to 43%), mitochondrial membrane potential (17% to 25%), and the uncoupler control ratio (UCR) of respiration (from 5.1 +/- 0.7 to 7.3 +/- 0.6 and 2.1 +/- 0.3 to 6.1 +/- 0.7) for PP and PV mitochondria, respectively. Thus, these effects of SAM suggest that it may be a useful agent to preserve the disturbed mitochondrial integrity in liver disease caused by alcoholism through maintenance of mitochondrial glutathione transport.

Depletion of brain glutathione is accompanied by impaired mitochondrial function and decreased N-acetyl aspartate concentration

The effect of depletion of reduced glutathione (GSH) on brain mitochondrial function and N-acetyl aspartate concentration has been investigated. Using pre-weanling rats, GSH was depleted by L-buthionine sulfoximine administration for up to 10 days. In both whole brain homogenates and purified mitochondrial preparations complex IV (cytochrome c oxidase) activity was decreased, by up to 27%, as a result of this treatment. In addition, after 10 days of GSH depletion, citrate synthase activity was significantly reduced, by 18%, in the purified mitochondrial preparations, but not in whole brain homogenates, suggesting increased leakiness of the mitochondrial membrane. The whole brain N-acetyl aspartate concentration was also significantly depleted at this time point, by 11%. It is concluded that brain GSH is important for the maintenance of optimum mitochondrial function and that prolonged depletion leads also to loss of neuronal integrity. The relevance of these findings to Parkinson's disease and the inborn errors of glutathione metabolism are also discussed.

Effect of acute ethanol exposure on cultured fetal rat hepatocytes: relation to mitochondrial function

Studies from our laboratory have shown that short-term ethanol exposure inhibits epidermal growth factor-dependent replication of cultured fetal rat hepatocytes, along with a drop in ATP level, and that these effects could be caused, at least in part, by ethanol-induced oxidative stress. In these prior studies, mitochondrial morphology was abnormal and membrane lipid peroxidation products were increased, along with reduced transmembrane potential and enhanced permeability to sucrose. To define the effects of ethanol on mitochondrial function further, the present study examines the impact of ethanol exposure on mitochondrial electron transport chain components. A 24-hr exposure of cultured fetal rat hepatocytes to ethanol (2.5 mg/ml) reduced mitochondrial complex I activity by 16% (p < 0.05), complex IV by 28% (p < 0.05), and succinate dehydrogenase by 23% (p < 0.05). This reduction was paralleled by lower ADP translocase activity (24%, p < 0.05) and diminished mitochondrial glutathione (GSH) (20%, p < 0.05). Pretreatment with 0.1 mM S-adenosyl methionine, before ethanol exposure, normalized mitochondrial GSH along with activities of complex I, complex IV, and succinate dehydrogenase. A 3-hr exposure of isolated mitochondria (which do not metabolize ethanol) to ethanol (2.5 mg/ml), inhibited the activities of complex I (19%, p < 0.05), complex IV (24%, p < 0.05), and of ATP synthesis (20%, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)