Reduction of carbon tetrachloride-induced rat liver injury by IRFI 042, a novel dual vitamin E-like antioxidant

Antioxidant Activity and Hepatoprotective Effect of Exopolysaccharides From Cultivated Ophiocordyceps Sinensis Against CCl4-Induced Liver Damages

Cordyceps is a well-known and valuable fungal Chinese medicine and health food. The polysaccharides from C. sinensis have been reported as the main bioactive components, which possess antioxidant, anti-aging, and liver protective activities. This study aimed to investigate the in vitro antioxidative and protective effects of exopolysaccharides (EPS) from cultivated Ophiocordyceps sinensis (O. sinensis) on rats with liver damage induced by CCl4. The results indicated that cultivated O. sinensis EPS possess moderate ABTS and hydroxyl radical scavenging abilities with IC50 values of 2.00 and 3.78 mg/mL, respectively. EPS and the positive control (silymarin) could also protect rat liver from the oxidative effect induced by CCl4 via increasing GSH levels, reducing MAD levels and decreasing serum AST and ALT activities. Moreover, the changes in histopathological liver tissue showed that EPS significantly reduced the damage induced by CCl4 in the liver. The findings suggest that EPS possesses a significant hepatoprotective effect against hepatotoxicity induced by CCl4 in rats.

Extracts from Fermented Black Garlic Exhibit a Hepatoprotective Effect on Acute Hepatic Injury

The mechanism of hepatoprotective compounds is usually related to its antioxidant or anti-inflammatory effects. Black garlic is produced from garlic by heat treatment and its anti-inflammatory activity has been previously reported. Therefore, the aim of this study was to investigate the hepatoprotective effect of five different extracts of black garlic against carbon tetrachloride (CCl₄)-induced acute hepatic injury (AHI). In this study, mice in the control, CCl₄, silymarin, and black garlic groups were orally administered distilled water, silymarin, and different fraction extracts of black garlic, respectively, after CCl₄ was injected intraperitoneally to induce AHI. The results revealed that the n-butanol layer extract (BA) and water layer extract (WS) demonstrated a hepatoprotective effect by reducing the levels of alanine aminotransferase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), and hepatic malondialdehyde (MDA). Furthermore, the BA and WS fractions of black garlic extract increased the activity of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), glutathione reductase (GSH-Rd), tumor necrosis factor alpha (TNF-α), and the interleukin-1 (IL-1β) level in liver. It was concluded that black garlic exhibited significant protective effects on CCl₄-induced acute hepatic injury.

Preventive Effect of Blueberry Extract on Liver Injury Induced by Carbon Tetrachloride in Mice

The blueberry is a common fruit that is rich in nutritional value and polyphenol substances. In this study, the blueberry polyphenol content in extract was analysed by spectrophotometry. The results showed that the blueberry polyphenol content in the extract reached 52.7%. A mouse model of liver injury induced by carbon tetrachloride (CCl₄) was established to study the preventive effect of blueberry extract (BE) on liver injury in mice and the experimental animals were examined using biochemical and molecular biological methods. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) are important clinical liver function indicators; the changes of triglyceride (TG) and total cholesterol (TC) are observed after liver injury; interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) are important inflammatory indexes; superoxide dismutase (SOD) activity and thiobarbituric acid reactive substances (TBARS) are important changes of oxidative stress indexes. The in vivo animal experiment results showed that BE decreased the liver index of mice with liver injury, BE could reduce the AST, ALT, TG and TC levels and also could reduce the serum cytokine IL-6, TNF-α and IFN-γ levels in mice with liver injury. Moreover, BE increased the SOD activity and decreased the TBARS level in the gastric tissues of mice with liver injury. After treatment with the highest concentration of BP in liver injury mice, these levels returned close to those obtained after treatment with the standard drug of silymarin. Detection of messenger RNA (mRNA) in liver tissue showed that BE upregulated the Cu/Zn-SOD, Mn-SOD and chloramphenicol acetyltransferase (CAT) expression levels and downregulated cyclooxygenase (COX)-2 expression. The effect of BE on mice with liver injury was positively correlated with the BE concentration and was similar to that of silymarin, which is a drug for liver injury, suggesting that BE had a good preventive effect on liver injury. Thus, BE rich in polyphenols is a bioactive substance with value for development and utilization.

Capparis spinosa leaves extract: Source of bioantioxidants with nephroprotective and hepatoprotective effects

Capparis spinosa, Capparidaceae, is largely distributed all over the Mediterranean Basin and is traditionally used to treat many illnesses, such as liver and kidney diseases. The aim of the current study was to explore the antioxidant, nephroprotective and hepatoprotective effects of methanolic extract of Capparis spinosa leaves (MECS) associated with its phytochemical content. The levels of total phenolics, flavonoids and condensed tannins were 23.37mgGAE/g, 9.05mgQE/g and 9.35mgTAE/g, respectively. HPLC analysis revealed nine compounds, namely rutin, resveratrol, coumarin, epicatechin, luteolin, catechin, kaempferol, vanillic acid and gallic acid. The MECS showed interesting antioxidant capacity. The MECS-treatment significantly reduced the increased plasma levels of creatinine, urea and uric acid, reduced the elevated MDA levels, significantly reduced the antioxidant enzyme activities and restored the kidney damage, provoked by cisplatin-treatment. Furthermore, MECS-treatment significantly prevented the increase in serum ALT, AST and LDH levels in acute liver damage induced by CCl₄, decreased the amount of hepatic malondialdehyde (MDA) formation and elevated the activities of SOD, CAT and GPx, and restored liver injury. This study supports the traditionally use of C. spinosa to cure kidney and liver diseases. The obtained results highlighted the possible use of C. spinosa as a source of phytochemical with important biological advantages.

Antioxidant and proapoptotic effects of anthocyanins from bilberry extract in rats exposed to hepatotoxic effects of carbon tetrachloride

AIMS

The aim of this research was to determine the hepatoprotective effects of anthocyanins from bilberry extract in rats exposed to carbon tetrachloride (CCl4) by monitoring the parameters of oxidative stress and apoptosis, and by performing the histopathological and morphometric analyses.

MAIN METHODS

Animals were divided into four groups: Group I (0.9% NaCl-10days), Group II (bilberry extract, 75mg/kg-10days), Group III (0,9% NaCl-9days, and on the tenth day CCl4-2ml/kg), Group IV (bilberry extract, 75mg/kg-10days and on the tenth day CCl4-2ml/kg).

KEY FINDINGS

Bilberry extract led to a significant decrease in the activity of biochemical parameters in serum (AST, GGT, LDH, and ALT), the activity of pro-oxidative enzyme xanthine oxidase, as well as the level of lipid peroxidation in the liver in Group IV compared to Group III (p<0.01). Bilberry extract resulted in a significant increase in the activity of the antioxidant markers-catalase (p<0.05), superoxide dismutase, glutathione S-transferase and glutathione peroxidase (p<0.01), and the concentration of reduced glutathione (p<0.05) in Group IV in relation to Group III. The application of bilberry extract resulted in an increase in the number of apoptotic hepatocytes and the activity of caspase-3 in the liver tissue (p<0.01). The reduction of coagulation necrotic areas was proved (p<0.001) as well as the number of macrovesicular hepatocytes (p<0.01), along with an increased mitotic activity (p<0.01) in Group IV compared to Group III.

SIGNIFICANCE

Anthocyanins from bilberry extract have strong antioxidant properties and therefore can be considered as powerful hepatoprotectives in natural products.

Effects of curcumin on antioxidative activities and cytokine production in Jian carp (Cyprinus carpio var. Jian) with CCl4-induced liver damage

We investigated the protective effects of curcumin on liver-damaged Cyprinus carpio var. Jian (Jian carp). The carp were fed 0.1%, 0.5%, or 1.0% curcumin for 60 days, then injected intraperitoneally with 30% carbon tetrachloride solution. Liver and blood samples were collected to measure the liver index, serum- and liver-associated enzymes, liver histology, nuclear factor-κB (NF-κB)/c-Rel, interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and IL-12 mRNA expression, and the level of NF-κB/c-Rel protein in the liver, and for a comet assay. We found that 0.5% and 1.0% curcumin significantly reduced the CCl(4)-induced increase in the liver index. The comet assay showed that the tail moment, olive tail moment, tail length, and tail DNA% improved in fish pretreated with 0.5 or 1.0% curcumin. CCl(4)-induced histological changes, including extensive hepatocyte degeneration, indistinct cell borders, nuclear condensation, and karyolysis were clearly reduced after treatment with 0.5% and 1.0% curcumin. Moreover, 0.5% and 1.0% curcumin significantly inhibited the CCl(4)-induced increase in serum glutamic oxaloacetic transaminase and promoted the restoration of superoxide dismutase in the liver; 1.0% curcumin significantly reduced serum glutamic pyruvic transaminase and lactate dehydrogenase and hepatic malondialdehyde, but significantly increased the total antioxidant capacity and glutathione levels in the liver. The CCl(4)-induced upregulation of NF-κB/c-Rel, IL-1β, and TNF-α mRNAs and NF-κB/c-Rel protein levels was inhibited by 0.5% and 1.0% curcumin, and IL-12 mRNA was reduced by all three doses of curcumin. The effects of curcumin on the liver index, enzymes, histological changes, and cytokines were dose-dependent. Our results indicate that curcumin reduces CCl(4)-induced liver damage in Jian carp by upregulating antioxidative activities and inhibiting NF-κB, IL-1β, TNF-α, and IL-12 expression.

Effect of polycan, a β-glucan originating from Aureobasidium, on a high-fat diet-induced hyperlipemic hamster model

The aim of the present study was to analyze the effect of polycan, a β-glucan originating from Aureobasidium, on high-fat diet (HFD)-induced hyperlipemia and hepatic damage. A total of 30 hamsters were divided into 6 groups based on their body weight following acclimatization: control, sham, simvastatin (SIMVA) and 3 Polycan groups. In the polycan groups, Polycan, at three concentrations (31.25, 62.5 and 125 mg/kg), was administered orally once a day for 56 days, in addition to the HFD. On the day of sacrifice, changes in the body weight, food consumption, liver weight and serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride and total cholesterol (T-CHOL) were observed, as well as changes to the liver and aorta (thoracic and abdominal) histopathology and histomorphometry. The results from the polycan groups were compared with a SIMVA 10 mg/kg oral treatment group, in addition to the sham and vehicle control groups. After the HFD-induced hyperlipidemic hamsters were administered Polycan, there was no significant change in their body weight and food consumption when compared with the hamsters in the vehicle control group. However, the serum levels of AST, ALT, triglyceride, T-CHOL and LDL were significantly reduced in a dose-dependent manner when compared with the vehicle control group (P<0.05). Furthermore, the levels of liver steatosis and arteriosclerosis in the abdominal and thoracic aorta were significantly decreased in a dose-dependent manner (P<0.01). In the SIMVA-treated group, body weight (P<0.05), the serum level of lipids (triglyceride, T-CHOL and LDL; P<0.01) and the level of arteriosclerosis (P<0.01) were significantly reduced when compared with the vehicle control group. However, liver weight and the serum levels of AST, ALT, and liver steatosis increased when compared with the vehicle control group. Based on these results, it was concluded that polycan exerts a favorable effect in decreasing HFD-induced hyperlipemia and associated atherosclerosis, with relatively good protective effects on liver damage.

Solid phase synthesis of mitochondrial triphenylphosphonium-vitamin E metabolite using a lysine linker for reversal of oxidative stress

Mitochondrial targeting of antioxidants has been an area of interest due to the mitochondria's role in producing and metabolizing reactive oxygen species. Antioxidants, especially vitamin E (α-tocopherol), have been conjugated to lipophilic cations to increase their mitochondrial targeting. Synthetic vitamin E analogues have also been produced as an alternative to α-tocopherol. In this paper, we investigated the mitochondrial targeting of a vitamin E metabolite, 2,5,7,8-tetramethyl-2-(2′-carboxyethyl)-6-hydroxychroman (α-CEHC), which is similar in structure to vitamin E analogues. We report a fast and efficient method to conjugate the water-soluble metabolite, α-CEHC, to triphenylphosphonium cation via a lysine linker using solid phase synthesis. The efficacy of the final product (MitoCEHC) to lower oxidative stress was tested in bovine aortic endothelial cells. In addition the ability of MitoCEHC to target the mitochondria was examined in type 2 diabetes db/db mice. The results showed mitochondrial accumulation in vivo and oxidative stress decrease in vitro.

Potential antioxidant properties and hepatoprotective effects of an aqueous extract formula derived from three Chinese medicinal herbs against CCl(4)-induced liver injury in rats

The hepatoprotective effects of an aqueous extract formula (AEF) derived from Artemisia capillaris, Lonicera japonica and Silybum marianum (ratio 1:1:1) were evaluated by its antioxidant properties and its attenuation of carbon tetrachloride (CCl(4))-induced liver damage in rats. The antioxidant analyses revealed that the AEF showed higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and superoxide anion radical scavenging activities as well as ferric reducing antioxidant potential (FRAP) and Trolox equivalent antioxidant capacity (TEAC) compared with the individual herbs, suggesting a synergism in antioxidation between the three herbs. The animal experiments showed that the CCl(4) treatment increased serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, but decreased triglyceride (TG) and glutathione (GSH) levels as well as glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT) activities. However, AEF administration can successfully lower serum ALT and AST activities, restore the GSH level, ameliorate or restore GPx and CAT activities as well as improve SOD action depending on AEF dosage. Histological examination of liver showed that CCl(4) increased the extent of bile duct proliferation, necrosis, fibrosis and fatty vacuolation throughout the liver, but AEF can improve bile duct proliferation, vacuolation and fibrosis, and restore necrosis. The present study demonstrated the hepatoprotective potential of AEF as an alternative to the traditional silymarin.

Protection of the extracts of Lentinus edodes mycelia against carbon-tetrachloride-induced hepatic injury in rats

Lentinus edodes is the medicinal macrofungus showing potential for therapeutic applications in infectious disorders including hepatitis. In an attempt to develop the agent for handling hepatic injury, we used the extracts of Lentinus edodes mycelia (LEM) to screen the effect on hepatic injury in rats induced by carbon tetrachloride (CCl₄). Intraperitoneal administration of CCl₄ not only increased plasma glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) but also decreased hepatic superoxide dismutase (SOD) and glutathione peroxidase (GPx) levels in rats. Similar to the positive control silymarin, oral administration (three times daily) of this product (LEM) for 8 weeks significantly reduced plasma GOT and GPT. Also, the activities of antioxidant enzymes of SOD and GPx were elevated by LEM. in liver from CCl₄-treated rats, indicating that mycelium can increase antioxidant-like activity. Moreover, the hepatic mRNA and protein levels of SOD and GPx were both markedly raised by LEM. The obtained results suggest that oral administration of the extracts of Lentinus edodes mycelia (LEM) has the protective effect against CCl₄-induced hepatic injury in rats, mainly due to an increase in antioxidant-like action.

Green tea extract supplementation ameliorates CCl4-induced hepatic oxidative stress, fibrosis, and acute-phase protein expression in rat

BACKGROUND/PURPOSE

We evaluated the long-term effects of green tea extract (GTE) supplementation on oxidative stress, biliary acute phase protein expression, and liver function in CCl(4)-induced chronic liver injury.

METHODS

We evaluated the antioxidant activity of GTE in comparison with those of vitamin C, vitamin E, and β-carotene in vitro by using an ultrasensitive chemiluminescence analyzer. Chronic liver injury was induced by intraperitoneally administering carbon tetrachloride (CCl(4)) (1 mL/kg body weight, twice weekly) to female Wistar rats for 8 weeks. The effects of low (4 mg/kg body weight per day) and high (20 mg/kg body weight per day) doses of intragastric GTE on CCl(4)-induced liver dysfunction and fibrosis were examined by measuring the bile and blood reactive oxygen species levels and biochemical parameters by using Western blot and two-dimensional polyacrylamide gel electrophoresis techniques.

RESULTS

GTE has greater scavenging activity against O(2)(-), H(2)O(2), and Hypochlorous acid (HOCl) in vitro than vitamin C, vitamin E, and β-carotene do. In vivo, CCl(4) markedly increased bile and blood reactive oxygen species production, lipid accumulation, number of infiltrated leukocytes, fibrosis, hepatic hydroxyproline content, and plasma alanine aminotransferase and aspartate aminotransferase activities, and reduced plasma albumin levels. Two-dimensional polyacrylamide gel electrophoresis revealed that CCl(4) increased the acute-phase expression of six biliary proteins and decreased hepatic B-cell lymphoma 2 (Bcl-2), catalase, and CuZn superoxide dismutase protein expression. GTE supplementation attenuated CCl(4)-enhanced oxidative stress, levels of biochemical parameters, pathology, and acute-phase protein secretion, and preserved antioxidant/antiapoptotic protein expression.

CONCLUSION

GTE supplementation attenuates CCl(4)-induced hepatic oxidative stress, fibrosis, acute phase protein excretion, and hepatic dysfunction via the antioxidant and antiapoptotic defense mechanisms.

Carbon tetrachloride-mediated lipid peroxidation induces early mitochondrial alterations in mouse liver

Although carbon tetrachloride (CCl(4))-induced acute and chronic hepatotoxicity have been extensively studied, little is known about the very early in vivo effects of this organic solvent on oxidative stress and mitochondrial function. In this study, mice were treated with CCl(4) (1.5 ml/kg ie 2.38 g/kg) and parameters related to liver damage, lipid peroxidation, stress/defense and mitochondria were studied 3 h later. Some CCl(4)-intoxicated mice were also pretreated with the cytochrome P450 2E1 inhibitor diethyldithiocarbamate or the antioxidants Trolox C and dehydroepiandrosterone. CCl(4) induced a moderate elevation of aminotransferases, swelling of centrilobular hepatocytes, lipid peroxidation, reduction of cytochrome P4502E1 mRNA levels and a massive increase in mRNA expression of heme oxygenase-1 and heat shock protein 70. Moreover, CCl(4) intoxication induced a severe decrease of mitochondrial respiratory chain complex IV activity, mitochondrial DNA depletion and damage as well as ultrastructural alterations. Whereas DDTC totally or partially prevented all these hepatic toxic events, both antioxidants protected only against liver lipid peroxidation and mitochondrial damage. Taken together, our results suggest that lipid peroxidation is primarily implicated in CCl(4)-induced early mitochondrial injury. However, lipid peroxidation-independent mechanisms seem to be involved in CCl(4)-induced early hepatocyte swelling and changes in expression of stress/defense-related genes. Antioxidant therapy may not be an efficient strategy to block early liver damage after CCl(4) intoxication.

Hepatoprotective effect of Scoparia dulcis on carbon tetrachloride induced acute liver injury in mice

This study aims to investigate the hepatoprotective activity and active constituents of the ethanol extract of Scoparia dulcis (SDE). The hepatoprotective effect of SDE (0.1, 0.5 and 1 g/kg) was evaluated on the carbon tetrachloride (CCl(4))-induced acute liver injury. The active constituents were detected by high performance liquid chromatography (HPLC). Mice pretreated orally with SDE (0.5 and 1.0 g/kg) and silymarin (200 mg/kg) for five consecutive days before the administering of a single dose of 0.2% CCl(4) (10 ml/kg of bw, ip) showed a significant inhibition of the increase of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Histological analyses also showed that SDE (0.5 and 1.0 g/kg) and silymarin reduced the extent of liver lesions induced by CCl(4), including vacuole formation, neutrophil infiltration and necrosis. Moreover, SDE decreased the malondialdehyde (MDA) level and elevated the content of reduced glutathione (GSH) in the liver as compared to those in the CCl(4) group. Furthermore, SDE (0.5 and 1.0 g/kg) enhanced the activities of anti-oxidative enzymes including superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GRd) and glutathione-S-transferase (GST). The quantities of active constituents in SDE were about 3.1 mg luteolin/g extract and 1.1 mg apigenin/g extract. The hepatoprotective mechanisms of SDE were likely associated to the decrease in MDA level and increase in GSH level by increasing the activities of antioxidant enzymes such as SOD, GPx, GRd and GST. These results demonstrated that SDE could alleviate CCl(4)-induced acute liver injury in mice.

Antihepatotoxic and Antioxidant Activities of Methanol Extract and Isolated Compounds from Ficus Chlamydocarpa

Free radicals, in particular radical oxygen species (ROS), play an important role in the aetiology and pathogenesis of various diseases. Current research in many countries focuses on the use of local medicinal plants as a promising source of liver protective agents. This paper describes the hepatoprotective effects of the methanol extract and four isolated compounds from Ficus chlamydocarpa on CCl4-induced liver damage, as well as the possible antioxidant mechanisms involved in this protection. The DPPH test, along with the ß-Carotene-Linoleic Acid Model System and Ferric-Reducing Antioxidant Power assays, as well as the inhibition of microsomal lipid peroxidation were used to measure radical-scavenging and antioxidant activities. Pretreatment of rats with the methanol extract of F. chlamydocarpa before CCl4 administration, significantly prevented serum increase of hepatic enzyme markers, glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT), in a dose-dependent manner. The hepatoprotection was also associated with a significant enhancement in hepatic reduced glutathione (GSH) and a marked decrease of liver malondialdehyde (MDA). Among the four compounds 1-4, isolated from the methanol extract, α-amyrin acetate (1) and luteolin (4) showed a significant hepatoprotective activity, as indicated by their ability to prevent liver cell death and lactate dehydrogenase (LDH) leakage during CCl4 intoxication.

Protective effect of fermented sea tangle against ethanol and carbon tetrachloride-induced hepatic damage in Sprague-Dawley rats

Sea tangle has long been used as Korean folk remedy to promote material health, and is one of the popular dietary supplement. This study was designed to evaluate the protective effect of fermented sea tangle (FST) against ethanol and carbon tetrachloride (CCl(4))-induced hepatotoxicity in rats. Sprague-Dawley rats were orally treated with FST (25, 250, 2500 mg/kg/day) with administration of ethanol (5 mL/kg) for 13 weeks and the single intraperitoneal (i.p.) dose of 50% CCl(4) (5 mL/kg/day, CCl(4) in olive oil) at 12 week, and repeated i.p. dose of 20% CCl(4) (2 mL/kg/day) for 1 week. Hepatotoxicity was evaluated by measuring the serum levels of glutamic pyruvate transaminase (GPT), gamma glutamyl transpeptidase (gamma-GT) and malondialdehyde (MDA) as well as the tissue levels of antioxidant enzyme such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). Ethanol and CCl(4)-induced the rat liver damage, and significantly increased (p<0.05) the GPT, gamma-GT and MDA levels, and decreased the SOD, CAT and GPx levels. However, treatment with FST could decrease serum GPT, gamma-GT, and MDA levels significantly in plasma, and increase the activities of SOD, CAT, and GPx in liver tissues compared with ethanol and CCl(4)-treated group.

Protective effects of silica hydride against carbon tetrachloride-induced hepatotoxicity in mice

The protective effects of MegaHydrate silica hydride against liver damage were evaluated by its attenuation of carbon tetrachloride (CCl(4))-induced hepatotoxicity in mice. Male ICR mice were orally treated with silica hydride (104, 208 and 520 mg/kg) or silymarin (200 mg/kg) daily, with administration of CCl(4) (1 mL/kg, 20% CCl4 in olive oil) twice a week for eight weeks. The results showed that oral administration of silica hydride significantly reduced the elevated serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), triglyceride (TG), and cholesterol and the level of malondialdehyde (MDA) in the liver that were induced by CCl(4) in mice. Moreover, the silica-hydride treatment was also found to significantly increase the activities of superoxide dismutase (SOD), catalase, and glutathione peroxidase (GSH-Px), as well as increase the GSH content, in the liver. Liver histopathology also showed that silica hydride reduced the incidence of liver lesions induced by CCl(4). The results suggest that silica hydride exhibits potent hepatoprotective effects on CCl(4)-induced liver damage in mice, likely due to both the increase of antioxidant-defense system activity and the inhibition of lipid peroxidation.

Choleretic activity of 2-demethoxycarbonyl-2-ethoxycarbonyl-11-deoxymisoprostol on the model of CCl4-induced hepatitis

Therapeutic administration of 11-deoxymisoprostol had a hepatoprotective effect, which manifested in a decrease in the content of alanine transaminase and aspartate transaminase in blood plasma, and produced a choleretic effect in rats with CCI4-induced toxic hepatitis.

Protective effects of puerarin on carbon tetrachloride-induced hepatotoxicity

Puerarin, the main isoflavone glycoside found in the root of Pueraria lobata, has been used for various medicinal purposes in traditional Chinese medicine for thousands of years. The purpose of this study was to investigate the protective effects of puerarin against hepatotoxicity induced by carbon tetrachloride (CCl4) and the mechanism of its hepatoprotective effect. In mice, pretreatment with puerarin prior to the administration of CCl4 significantly prevented the increased serum enzymatic activity of alanine aspartate aminotransferase and hepatic malondialdehyde formation in a dose-dependent manner. In addition, pretreatment with puerarin significantly prevented both the depletion of reduced glutathione (GSH) content and the decrease in glutathione S-transferase (GST) activity in the liver of CCl4-intoxicated mice. Hepatic GSH levels and GST activity were increased by treatment with puerarin alone. CCl4-induced hepatotoxicity was also prevented, as indicated by liver histopathology. The effects of puerarin on cytochrome P450 (CYP) 2E1, the major isozyme involved in CCl4 bioactivation, were also investigated. Treatment of the mice with puerarin resulted in a significant decrease in the CYP2E1-dependent aniline hydroxylation in a dose-dependent manner. Consistent with these observations, the CYP2E1 protein levels were also lowered. Puerarin exhibited anti-oxidant effects on FeCl2-ascorbate induced lipid peroxidation in mouse liver homogenates, and on superoxide radical scavenging activity. These results suggest that the protective effects of puerarin against the CCl4-induced hepatotoxicity possibly involve mechanisms related to its ability to block CYP-mediated CCl4 bioactivation, induction of GST activity and free radical scavenging effects.

Protection against oxidative stress-induced hepatic injury by intracellular type II platelet-activating factor acetylhydrolase by metabolism of oxidized phospholipids in vivo

Membrane phospholipids are susceptible to oxidation, which is involved in various pathological processes such as inflammation, atherogenesis, neurodegeneration, and aging. One enzyme that may help to remove oxidized phospholipids from cells is intracellular type II platelet-activating factor acetylhydrolase (PAF-AH (II)), which hydrolyzes oxidatively fragmented fatty acyl chains attached to phospholipids. Overexpression of PAF-AH (II) in cells or tissues was previously shown to suppress oxidative stress-induced cell death. In this study we investigated the functions of PAF-AH (II) by generating PAF-AH (II)-deficient (Pafah2(-/-)) mice. PAF-AH (II) was predominantly expressed in epithelial cells such as kidney proximal and distal tubules, intestinal column epithelium, and hepatocytes. Although PAF-AH activity was almost abolished in the liver and kidney of Pafah2(-/-) mice, Pafah2(-/-) mice developed normally and were phenotypically indistinguishable from wild-type mice. However, mouse embryonic fibroblasts derived from Pafah2(-/-) mice were more sensitive to tert-butylhydroperoxide treatment than those derived from wild-type mice. When carbon tetrachloride (CCl(4)) was injected into mice, Pafah2(-/-) mice showed a delay in hepatic injury recovery. Moreover, after CCl(4) administration, liver levels of the esterified form of 8-iso-PGF(2alpha), a known in vitro substrate of PAF-AH (II), were higher in Pafah2(-/-) mice than in wild-type mice. These results indicate that PAF-AH (II) is involved in the metabolism of esterified 8-isoprostaglandin F(2alpha) and protects tissue from oxidative stress-induced injury.

Hepatoprotective and antioxidant effects of the coffee diterpenes kahweol and cafestol on carbon tetrachloride-induced liver damage in mice

The hepatoprotective effects of kahweol and cafestol, coffee-specific diterpenes, on the carbon tetrachloride (CCl(4))-induced liver damage as well as the possible mechanisms involved in these protections were investigated. Pretreatment with kahweol and cafestol prior to the administration of CCl(4) significantly prevented the increase in the serum levels of hepatic enzyme markers (alanine aminotransferase and aspartate aminotransferase) and reduced oxidative stress, such as reduced glutathione content and lipid peroxidation, in the liver in a dose-dependent manner. The histopathological evaluation of the livers also revealed that kahweol and cafestol reduced the incidence of liver lesions induced by CCl(4). Treatment of the mice with kahweol and cafestol also resulted in a significant decrease in the cytochrome P450 2E1 (CYP2E1), the major isozyme involved in CCl(4) bioactivation, specific enzyme activities, such as p-nitrophenol and aniline hydroxylation. Kahweol and cafestol exhibited antioxidant effects on FeCl(2)-ascorbate induced lipid peroxidation in a mouse liver homogenate, and on superoxide radical scavenging activity. These results suggest that the protective effects of kahweol and cafestol against the CCl(4)-induced hepatotoxicity possibly involve mechanisms related to their ability to block the CYP2E1-mediated CCl(4) bioactivation and free radical scavenging effects.

Du-Zhong (Eucommia ulmoides Oliv.) leaves inhibits CCl4-induced hepatic damage in rats

The protective effects of water extract of Du-Zhong (Eucommia ulmoides Oliv.) leaves (WEDZ) and its active compound (protocatechuic acid; PCA) on liver damage were evaluated by carbon tetrachloride (CCl4)-induced chronic hepatotoxicity in rats. Wistar rats were orally treated with WEDZ (0.1, 0.5, and 1.0 g/kg bw) or PCA (0.1 g/kg bw) with administration of CCl4 (0.5 ml/rat, 20% CCl4 in olive oil) for 28 consecutive days. It showed that CCl4-treated rats increased the relative organ weights of liver and kidney. CCl4-induced rats liver damage and significantly (p<0.05) increased the GOT, GPT, LDH and ALP levels in serum as compared with the control group. Treatment with WEDZ or PCA could decrease the GOT, GPT, LDH and ALP levels in serum when compared with CCl4-treated group. CCl4-treated rats also significantly (p<0.05) decreased the GSH content in liver and trolox equivalent antioxidant capacity (TEAC) in serum whereas increased (p<0.05) MDA content in liver as compared with the control group. Treatment with WEDZ or PCA also significantly (p<0.05) increased the GSH content and significantly (p<0.05) decreased the MDA content in liver. Administration of WEDZ or PCA could increase the activities of GPx, GRd and GST in liver. Liver histopathology showed that WEDZ or PCA reduced the incidence of liver lesions including hepatic cells cloudy swelling, lymphocytes infiltration, cytoplasmic vacuolization, hepatic necrosis and fibrous connective tissue proliferated induced by CCl4 in rats. The data suggest that oral administration with WEDZ for 28 consecutive days significantly decrease the intensity of hepatic damage induced by CCl4 in rats.

In vitro and in vivo protective effects of proteoglycan isolated from mycelia of Ganoderma lucidum on carbon tetrachloride-induced liver injury

AIM: To investigate the possible mechanism of the protective effects of a bioactive fraction, Ganoderma lucidum proteoglycan (GLPG) isolated from Ganoderma lucidum mycelia, against carbon tetrachloride-induced liver injury.

METHODS: A liver injury model was induced by carbon tetrachloride. Cytotoxicity was measured by MTT assay. The activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined with an automatic multifunction-biochemical analyzer and the levels of superoxide dismutase (SOD) and TNF-α were determined following the instructions of SOD kit and TNF radioimmunoassay kit. Liver sections were stained with hematoxylin and eosin (H&E) for histological evaluation and examined under light microscope.

RESULTS: We found that GLPG can alleviate the L-02 liver cells injury induced by carbon tetrachloride (CCl₄) through the measurements of ALT and AST activities and the administration of GLPG to L-02 cells did not display any toxicity. Furthermore, histological analysis of mice liver injury induced by CCl₄ with or without GLPG pretreatment indicated that GLPG can significantly suppress the toxicity induced by CCl₄ in mice liver. We also found that GLPG reduced TNF-α level induced by CCl₄ in the plasma of mice, whereas increased SOD activity in the rat serum.

CONCLUSION: GLPG has hepatic protective activity against CCl₄-induced injury both in vitro and in vivo. The possible anti-hepatotoxic mechanisms may be related to the suppression of TNF-α level and the free radical scavenging activity.

Honokiol protects against carbon tetrachloride induced liver damage in the rat

This study aims to investigate the possible hepato-protective effects of honokiol against liver damage and cirrhosis induced by carbon tetrachloride (CCl(4)) in the rat. Rats were treated acutely, or chronically with CCl(4) at 5 day intervals (0.06 mL/100 g body weight, administered as 50% vol/vol solution in liquid paraffin) by gavage, in combination with phenobarbitone in drinking water (0.5 g/L for 7 days prior to, and during CCl(4) treatment) to induce liver damage. Some were also co-treated with 0.1 mg/kg or 0.03 mg/kg honokiol (i.p.) or with appropriate vehicle. In vivo measurement of the liver sinusoidal area was performed using confocal microscopy following i.v. fluorescein isothiocyanate (FITC) dextran. Liver histology and function tests were performed, and liver and body weights were measured. Confocal microscopy showed that acute and chronic CCl(4) treatment significantly reduced the sinusoidal area. Honokiol (0.1 mg/kg, but not 0.03 mg/kg) partially reversed the decrease in the sinusoidal area after acute or chronic treatments with CCl(4). Acute and chronic CCl(4) treatment produced significant histological liver damage. Honokiol (0.1 mg/kg) significantly reduced the histological damage caused by chronic treatment. Chronic treatment with CCl(4) caused a significant increase in the bilirubin level that was not observed following the high dose of honokiol (0.1 mg/kg). In conclusion, this study showed that honokiol exhibits potent hepato-protective effects in rats treated with CCl(4).

Liver targeting of catalase by cationization for prevention of acute liver failure in mice

To achieve hepatic delivery of CAT for the prevention of CCl4-induced acute liver failure in mice, two types of cationized CAT derivatives, HMD- and ED-conjugated CAT, were developed. Slight structural changes occurred during cationization and the number of increased free amino groups was 3.1 in HMD-CAT and 13.6 in ED-CAT. 111In-cationized CAT derivatives showed an increased binding to HepG2 cells, and were rapidly taken up by the liver. H2O2-induced cytotoxicity in HepG2 cells was significantly prevented by preincubation of the cells with cationized CAT derivatives. A bolus intravenous injection of the cationized CAT derivatives reduced the hepatotoxicity induced by CCl4 in mice. The ED-CAT, which showed more rapid and greater binding to the liver than the HMD-CAT, exhibited more beneficial effects as far as all the parameters examined (serum GOT, GPT, LDH and hepatic GSH) were concerned, suggesting that a high degree of cationization is effective in delivering CAT to the liver to prevent CCl4-induced hepatotoxicity. These results suggest that cationized CAT derivatives are effective in preventing acute liver failure, and ED-based cationization is a suitable method for developing liver-targetable cationized CAT derivatives, because it provides CAT with a high degree of cationization and a high remaining enzymatic activity.

Inhibition of lipid peroxidation by IRFI 042, a vitamin E analogue, decreases monensin cardiotoxicity in chicks

Monensin, a well-known ionophore antibiotic, may cause severe damage in myocardial cells. We investigated whether IRFI 042, a new analogue of vitamin E, may block lipid peroxidation in myocardial cells and in turn protect against monensin toxicity. Monensin toxicity was induced by repeated daily administration of the ionophore antibiotic (150 mg/kg/day for 7 days). Sham animals received by oral gavages only a saline solution and were used as controls. All animals were randomized to receive concomitantly by oral gavages IRFI 042 (20 mg/kg) or its vehicle. The experiment lasted 8 days. Survival rate, heart lipid peroxidation, studied by means of thiobarbituric acid-reactive substances (TBARs) levels, cardiac expression of endothelial nitric oxide (e-NOS) and histological analysis of the heart were performed. Monensin administration caused a decrease in survival rate. Mortality appeared following the second monensin injection and at day 7 caused a survival rate of 20%. Thereafter, no further mortality was observed. IRFI 042 administration improved survival rate. Injection of the ionophore antibiotic resulted in a marked cardiac lipid peroxidation and in a significant reduction in cardiac e-NOS message and protein expression. IRFI 042 decreased heart TBARs levels (Monensin + vehicle = 6.5 +/- 0.8 nmol/mg; Monensin + IRFI 042 = 3.2 +/- 1.1 nmol/mg; P < 0.001) and increased e-NOS message and protein expression. Histological analysis showed that IRFI 042 improved myocardial cells damage and enhanced the depressed e-NOS expression in chick heart samples following monensin administration. Our data suggest that IRFI 042 is a promising drug to reduce monensin cardio-toxicity in chicks.

Lipid peroxidation induced by carbon tetrachloride and its inhibition by antioxidant as evaluated by an oxidative stress marker, HODE

We have recently proposed total hydroxyoctadecadienoic acid (HODE) as a biomarker for oxidative stress in vivo. The biological samples such as plasma, urine, and tissues were first reduced and then saponified to convert the oxidation products of linoleate to HODE. In the present study, this method was applied to measure the oxidative damage induced by the administration of carbon tetrachloride to mice and also to evaluate the capacity of antioxidant to inhibit the above damage. alpha-Tocopherol transfer protein knock out (alpha-TTP-/-) mice were used to evaluate antioxidant effect in the absence of alpha-tocopherol. The intraperitoneal administration of carbon tetrachloride to mice induced the increase in HODE in liver and plasma, which was followed by an increase in plasma glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT). F2-isoprostanes, another prevailing biomarker, were also increased similarly, but their concentration was approximately two to three orders of magnitude smaller than that of HODE. The lipophilic antioxidants such as gamma-tocopherol, gamma-tocotrienol and 2,3-dihydro-5-hydroxy-4,6-di-tert-butyl-2,2-dipentylbenzofuran (BO-653) were effective in suppressing the formation of HODE.

Melatonin-selenium nanoparticles inhibit oxidative stress and protect against hepatic injury induced by Bacillus Calmette-Guérin/lipopolysaccharide in mice

Melatonin-selenium nanoparticles (MT-Se), a novel complex, were synthesized by preparing selenium nanoparticles in melatonin medium. The present investigation was designed to determine the protective effects of MT-Se against Bacillus Calmette-Guérin (BCG)/lipopolysaccharide (LPS)-induced hepatic injury in mice. In BCG/LPS-induced hepatic injury model, MT-Se administered (i.g.) at doses of 5, 10, or 20 mg/kg to BCG/LPS-treated mice for 10 days, significantly reduced the increase in plasma aminotransferase, reduced the severe extent of hepatic cell damage and the immigration of inflammatory cells. The MT-Se particles also attenuated the increase in the content of thiobarbituric acid-reactive substances and enhanced the decrease in reduced activities of superoxide dismutase and glutathione peroxidase (GPx). However, treatment with MT-Se suppressed the increase in nitric oxide levels both in plasma and liver tissue. Furthermore, supplementation with MT-Se at the dose of 10 mg/kg (composed of 9.9 mg/kg melatonin and 0.1 mg/kg selenium) had great capability to protect against hepatocellular damage than a similar dose of melatonin (10 mg/kg) or selenium (0.1 mg/kg) alone. This effect may relate to its higher antioxidant efficacy in decreasing lipid peroxidation and increasing GPx activity. These results suggest that the mode of MT-Se hepatic protective action is, at least in part, related to its antioxidant properties.

Glutamate promotes NF-κB pathway in primary astrocytes: protective effects of IRFI 016, a synthetic vitamin E analogue

Oxidative stress has been implicated in several neurodegenerative diseases affecting both neuronal and glial cells. The aim of this study was to investigate the involvement of reactive oxygen species in glutamate-evoked activation of NF-kappaB in primary astrocytes. A prolonged exposure to glutamate (24 h) caused a depletion of intracellular glutathione that, in astroglial cells, has been considered a biochemical change typical of early astrocyte dysfunction, leading to cell alterations occurring in the gliosis. These effects were initiated by AMPA/KA receptor activation and almost completely blocked by anti-oxidants. Indeed, we provide evidence that the incubation of primary astrocytes with a hydrophilic derivative of tocopherol, such as IRFI 016, was useful to reduce glutamate-induced oxidative effects. This agent also reduced in a dose-dependent manner the nuclear translocation of both p50 and p65 subunits of NF-kappaB. Altogether, these data confirm that GSH content plays a pivotal role to determine oxidative response to glutamate injury in primary astrocyte cultures and that NF-kappaB pathway is involved in this response. Furthermore, the positive effects obtained by IRFI 016 to prevent nuclear translocation of NF-kappaB may suggest new pharmacological strategies for antioxidant therapy and neuroprotection.

Protective effects of antioxidant raxofelast in alcohol-induced liver disease in mice

We investigated the effect of raxofelast on lipid peroxidation inhibition in mice exposed to chronic ethanol. Female C57BL/6 mice were fed a modified Lieber-DeCarli liquid ethanol (ETOH) or control diet (sham ETOH) for up to 14 days. Animals were assigned to receive either raxofelast (20 mg/kg/day i.p.) or its vehicle (DMSO:NaCl 0.9% 1:1, v:v; 1 ml/kg i.p.). Serum alanine aminotransferase (ALT), plasma and liver triglyceride levels, hepatic malondialdehyde (MDA), reduced glutathione (GSH) concentrations, liver gene expression of Toll-like receptor-4 (TLR-4), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) and intercellular adhesion molecule-1 (ICAM-1) were studied at the end of the study. A histological evaluation of liver damage was also carried out. Raxofelast, an analog of vitamin E, blunted the increased hepatic nuclear factor-kappaB activity, reduced serum ALT, plasma and liver triglycerides, lowered hepatic MDA levels, prevented liver GSH depletion and decreased TLR-4, TNF-alpha, IL-6 and ICAM-1 hepatic gene expression. Furthermore raxofelast ameliorated liver damage. Our results suggest that raxofelast blunts the inflammatory cascade and organ damage during chronic ethanol exposure.

Effect of Enalpril on acute liver injury induced by CCl4 in rats and its anti-oxidative function

AIM: To investigate the effect of Enalpril on acute liver injury induced by carbon tetrachloride (CCl₄) in rats and its anti-oxidative function.

METHODS: Fifty normal male SD rats were randomly divided into five groups (10 rats/group): Enalpril interventional groups A, B, and C (10, 5, and 2.5 mg/kg, respectively), injury-model group, and control group. Rats in interventional and model groups were given hypodermic CCl₄ (diluted with an equal volume of olive oil). Rats in control group received normal saline injection. Rats with liver injury induced by CCl₄ were then treated with Enalpril (10, 5, 2.5; ig). The activities of serum aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP) and total bile acid (TBA) were detected using full automatic biochemical analyzer. Superoxide dismutase (SOD), xanthine oxidase (XOD), glutathione perioxidase (GSH-PX), and malondialdehyde (MDA) were determined using colorimetric method.

RESULTS: Enalpril significantly reduced serum ALT (685 ± 63, 1 241 ± 168, 1 705 ± 83, 2 302 ± 174 nkat/L vs> 3 531 ± 776 nkat/L in control, A, B, C versus model group respectively; P < 0.01), AST (1 240 ± 158, 2 430 ± 386 nkat/L vs> 3 372 ± 138 nkat/L in control, A versus model group; P < 0.01, P < 0.05 respectively), ALP (2 659 ± 248, 2 567 ± 159 nkat/L vs> 3 609 ± 346 nkat/L in control, A versus model group; P < 0.01) and TBA (8.48 ± 0.49, 16.35 ± 5.43, 16.92 ± 2.68 μmol/L vs> 24.16 ± 9.27 μmol/L in control, A, B versus model group; P < 0.01, P < 0.05, P < 0.05 respectively) in acute liver injury induced by CCl₄. The level of XOD in model group was significantly higher than that in control, A, B and C groups (1 042 ± 188 nkat/L vs> 571 ± 28, 724 ± 18, 821 ± 28, 868 ± 58 nkat/L; P < 0.01). SOD level in model group was significantly higher than that in control and A group (8 579 ± 861 nkat/L vs> 6 006± 639, 7 135 ± 1 560 nkat/L; P < 0.01, P < 0.05). MDA level in interventional group was obviously lower than that in model group and GSH-PX level was obviously higher than that in model group.

CONCLUSION: Enalpril has protective effects for rats with acute hepatic injury induced by carbon tetrachloride and the mechanism closely relates to its anti-oxidative function.

Modulation of IL-1 beta gene expression by lipid peroxidation inhibition after kainic acid-induced rat brain injury

Brain injury was induced by intraperitoneal administration of kainic acid (KA, 10 mg/kg). Animals were randomized to receive either IRFI 042 (20 mg/kg i.p.), a lipid peroxidation inhibitor, or its vehicle (NaCl 0.9% DMSO 10% 1 ml/kg i.p.) 30 min before KA administration. A first set of animals was sacrificed 6 h after KA injection to measure malondialdehyde (MDA) content, glutathione-reduced (GSH) levels and the mRNA for interleukin-1beta (IL-1beta) in the cortex and in the hippocampus. A second set of animals was sacrificed 48 h after KA administration for histological analysis. All animals were observed for monitoring the behavioral sequelae and for evaluating latency of convulsions. Sham brain injury rats were used as controls. Intraperitoneal administration of IRFI 042 significantly decreased brain MDA (cortex: KA + vehicle = 0.285 +/- 0.04 nmol/mg protein; KA + IRFI 042 = 0.156 +/- 0.02 nmol/mg protein, P < 0.005; hippocampus: KA + vehicle = 0.350 +/- 0.03 nmol/mg protein; KA + IRFI 042 = 0.17 +/- 0.04 nmol/mg protein, P < 0.005), prevented the brain loss of GSH in both cortex (KA + vehicle = 7.81 +/- 1 micromol/g protein; KA + IRFI 042 = 12.1 +/- 1 micromol/g protein; P < 0.005) and hippocampus (KA + vehicle = 5 +/- 0.8 micromol/g protein; KA + IRFI 042 = 9.4 +/- 1.8 micromol/g protein; P < 0.005), reduced both brain IL-1beta mRNA expression and oedema, and increased latency of convulsions. Histological analysis showed a reduction of cell damage in IRFI 042-treated samples. The present data indicate that lipid peroxidation inhibition reduces IL-1beta gene expression and protects against kainic acid-induced brain damage.

Hepatotoxicity and mechanism of action of haloalkanes: carbon tetrachloride as a toxicological model

The use of many halogenated alkanes such as carbon tetrachloride (CCl4), chloroform (CHCl3) or iodoform (CHI3), has been banned or severely restricted because of their distinct toxicity. Yet CCl4 continues to provide an important service today as a model substance to elucidate the mechanisms of action of hepatotoxic effects such as fatty degeneration, fibrosis, hepatocellular death, and carcinogenicity. In a matter of dose,exposure time, presence of potentiating agents, or age of the affected organism, regeneration can take place and lead to full recovery from liver damage. CCl4 is activated by cytochrome (CYP)2E1, CYP2B1 or CYP2B2, and possibly CYP3A, to form the trichloromethyl radical, CCl3*. This radical can bind to cellular molecules (nucleic acid, protein, lipid), impairing crucial cellular processes such as lipid metabolism, with the potential outcome of fatty degeneration (steatosis). Adduct formation between CCl3* and DNA is thought to function as initiator of hepatic cancer. This radical can also react with oxygen to form the trichloromethylperoxy radical CCl3OO*, a highly reactive species. CCl3OO* initiates the chain reaction of lipid peroxidation, which attacks and destroys polyunsaturated fatty acids, in particular those associated with phospholipids. This affects the permeabilities of mitochondrial, endoplasmic reticulum, and plasma membranes, resulting in the loss of cellular calcium sequestration and homeostasis, which can contribute heavily to subsequent cell damage. Among the degradation products of fatty acids are reactive aldehydes, especially 4-hydroxynonenal, which bind easily to functional groups of proteins and inhibit important enzyme activities. CCl4 intoxication also leads to hypomethylation of cellular components; in the case of RNA the outcome is thought to be inhibition of protein synthesis, in the case of phospholipids it plays a role in the inhibition of lipoprotein secretion. None of these processes per se is considered the ultimate cause of CCl4-induced cell death; it is by cooperation that they achieve a fatal outcome, provided the toxicant acts in a high single dose, or over longer periods of time at low doses. At the molecular level CCl4 activates tumor necrosis factor (TNF)alpha, nitric oxide (NO), and transforming growth factors (TGF)-alpha and -beta in the cell, processes that appear to direct the cell primarily toward (self-)destruction or fibrosis. TNFalpha pushes toward apoptosis, whereas the TGFs appear to direct toward fibrosis. Interleukin (IL)-6, although induced by TNFalpha, has a clearly antiapoptotic effect, and IL-10 also counteracts TNFalpha action. Thus, both interleukins have the potential to initiate recovery of the CCl4-damaged hepatocyte. Several of the above-mentioned toxication processes can be specifically interrupted with the use of antioxidants and mitogens, respectively, by restoring cellular methylation, or by preserving calcium sequestration. Chemicals that induce cytochromes that metabolize CCl4, or delay tissue regeneration when co-administered with CCl4 will potentiate its toxicity thoroughly, while appropriate CYP450 inhibitors will alleviate much of the toxicity. Oxygen partial pressure can also direct the course of CCl4 hepatotoxicity. Pressures between 5 and 35 mmHg favor lipid peroxidation, whereas absence of oxygen, as well as a partial pressure above 100 mmHg, both prevent lipid peroxidation entirely. Consequently, the location of CCl4-induced damage mirrors the oxygen gradient across the liver lobule. Mixed halogenated methanes and ethanes, found as so-called disinfection byproducts at low concentration in drinking water, elicit symptoms of toxicity very similar to carbon tetrachloride, including carcinogenicity.

Hyaluronic acid and chondroitin-4-sulphate treatment reduces damage in carbon tetrachloride-induced acute rat liver injury

Oxidative stress is involved in the pathogenesis of chemically mediated liver injury. Since glycosaminoglycans possess antioxidant activity, the aim of this work was to assess the protective effects of hyaluronic acid and chondroitin-4-sulphate treatment in a model of carbon tetrachloride-induced liver injury. Liver damage was induced in male rats by an intraperitoneal injection of carbon tetrachloride (1 ml/kg in vegetal oil). Serum alanine aminotransferase and aspartate aminotransferase, hepatic malondialdehyde, plasma TNF-alpha, hepatic reduced glutathione and catalase, and myeloperoxidase, an index of polymorphonuclear infiltration in the jeopardised hepatic tissue, were evaluated 24 h after carbon tetrachloride administration. Carbon tetrachloride produced a marked increase in serum alanine aminotransferase and aspartate aminotransferase activities, primed lipid peroxidation, enhanced plasma TNF-alpha levels, induced a severe depletion of reduced glutathione and catalase, and promoted neutrophil accumulation. Intraperitoneal treatment of rats with hyaluronic acid (25 mg/kg) or chondroitin-4-sulphate (25 mg/kg) failed to exert any effect in the considered parameter, while the combination treatment with both glycosaminoglycans (12,5 + 12,5 mg/kg) decreased the serum levels of alanine aminotransferase and aspartate aminotransferase, inhibited lipid peroxidation by reducing hepatic malondialdehyde, reduced plasma TNF-alpha, restored the endogenous antioxidants, and finally decreased myeloperoxidase activity. These results suggest that hyaluronic acid and chondroitin-4-sulphate possess a different antioxidant mechanism and consequently the combined administration of both glycosaminoglycans exerts a synergistic effect with respect to the single treatment.

Protective Effect of Acteoside on Carbon Tetrachloride-Induced Hepatotoxicity

This study investigated the protective effects of acteoside, a phenylethanoid glycoside, on the carbon tetrachloride-induced hepatotoxicity as well as the possible mechanisms involved in this protection in mice. Pretreatment with acteoside prior to the administration of carbon tetrachloride significantly prevented the increased serum enzymatic activities of alanine and aspartate aminotransferase in a dose-dependent manner. In addition, pretreatment with acteoside significantly prevented the increase in hepatic malondialdehyde formation and the depletion of the reduced glutathione content in the liver of carbon tetrachloride-intoxicated mice. Carbon tetrachloride-induced hepatotoxicity was also essentially prevented, as indicated by a liver histopathologic study. The effects of acteoside on cytochrome P450 (P450) 2E1, the major isozyme involved in carbon tetrachloride bioactivation were also investigated. Treatment of the mice with acteoside resulted in a significant decrease in the P450 2E1-dependent pnitrophenol and aniline hydroxylation in a dose-dependent manner. Consistent with these observations, the P450 2El protein levels were also lower. Acteoside exhibited anti-oxidant effects on FeCl2-ascorbate induced lipid peroxidation in a mouse liver homogenate, and on superoxide radical scavenging activity. These results suggest that the protective effects of acteoside against the carbon tetrachloride-induced hepatotoxicity possibly involve mechanisms related to its ability to block the P450-mediated carbon tetrachloride bioactivation and free radical scavenging effects.

Studies on liver-protection of Sorbaria sorbifolia aqueous extract

AIM

To study the liver-protection effects of Sorbaria sorbifolia aqueous extract.

METHODS

Sorbaria sorbifolia was perfused into stomach of the rats with liver injury induced by carbon tetrachloride and D-galactosamine. The activities of serum aspartate transaminase (AST), alanine transaminase (ALT), superoxide dismutase (SOD), glutathione perioxidase (GSH-PX), and malondialdehyde (MDA) were investigated by using colorimetric method.

RESULTS

The aqueous extract of Sorbaria sorbifolia significantly reduced serum ALT and AST in acute liver-injury induced by carbon tetrachloride and D-galactosamine, the activities of SOD and GSH-PX were signficantly higher in treated group than that in model group, and the MDA content in treated group was lower than that in model group.

CONCLUSION

The aqueous extract of Sorbaria sorbifolia has protecting effects for rats with acute hepatic injury induced by carbon tetrachloride and D-galactosamine.

Protective role of heme oxygenase-1 induction in carbon tetrachloride-induced hepatotoxicity

Reductive metabolism of carbon tetrachloride (CCl(4)) is thought to cause lipid peroxidation which results in hepatic injury. Heme oxygenase-1 (HO-1) (EC 1.14.99.3), the rate-limiting enzyme in heme catabolism, is known to be induced by oxidative stress and to confer protection against oxidative tissue injuries. In this study, we examined the role of HO-1 induction in a rat model of CCl(4)-induced acute liver injury. CCl(4) treatment (1 mL/kg, intraperitoneally) produced severe hepatic injury in rats as revealed by significant increases in serum alanine transaminase (ALT) (EC 2.6.1.2) activity and hepatic malondialdehyde (MDA) content, severe liver cell injury, and increases in hepatic tumor necrosis factor-alpha (TNF-alpha) mRNA expression and DNA binding activity of nuclear factor-kappa B (NF-kappa B). Following CCl(4) treatment, hepatic HO-1 expression was markedly increased both at transcriptional and protein levels in hepatocytes, especially around the central vein. HO-1 induction was mediated in part through a rapid increase in microsomal free heme concentration presumably derived from hepatic cytochrome P450. Inhibition of HO activity by tin-mesoporphyrin (Sn-MP), which resulted in a sustained increase in microsomal free heme concentration, exacerbated liver injury, as judged by the sustained increase in serum ALT activity, extensive hepatocytes injuries, a more pronounced expression of hepatic TNF-alpha mRNA and an enhanced NF-kappa B activation. These findings indicate that induction of HO-1 is an adaptive response to CCl(4) treatment, and it may be critical in the recovery of hepatocytes from injury. Our findings also suggest that HO-1 induction may play an important role in conferring protection on hepatocytes from oxidative damage caused by free heme.

Clinical usefulness of edaravone for acute liver injury

BACKGROUND

Edaravone, a newly synthesized radical scavenger, has shown an excellent effect on treating stroke patients. The effect of edaravone on carbon tetrachloride (CCl4)-induced acute liver injury was examined.

METHODS

Six rats were injected with CCl4 alone and six rats were intravenously injected with edaravone immediately after and 3 h after injection of CCl4. Another six rats were injected with olive oil alone. The animals were killed at 24 h after the CCl4 injection.

RESULTS

Injection of CCl4 was followed by a marked increase in serum alanine aminotranferase (ALT) level (CCl4, 1630.6 +/- 606.8 IU/L; olive oil, 21.0 +/- 2.6 IU/L; P < 0.001), lactate dehydrogenase (LDH) level (CCl4, 5068.0 +/- 2956.4 IU/L; olive oil, 203.6 +/- 30.5 IU/L; P < 0.005), and total bilirubin (TB) level (CCl4, 0.88 +/- 0.48 mg/dL; olive oil, 0.37 +/- 0.05 mg/dL; P < 0.01), whereas in the edaravone-treated rats, the ALT (119.4 +/- 113.5 IU/L, P < 0.001), LDH (369.7 +/- 288.2 IU/L, P < 0.005), and TB values (0.29 +/- 0.16 mg/dL, P < 0.01) were significantly decreased. Histological examination of the liver by hematoxylin and eosin and oil red O staining showed a marked reduction of steatosis in the CCl4 and edaravone-treated rats compared with the CCl4-injected rats. Significant inhibition of hepatocytic apoptosis was demonstrated by the terminal deoxynucleotidyl transferase-mediated UTP nick-end labeling (TUNEL) method in the edaravone-treated rats.

CONCLUSIONS

These results suggest that edaravone has a marked preventive effect on oxidative stress-induced acute liver injury.