Free-radical scavenging action of medicinal herbs from Ghana: Thonningia sanguinea on experimentally-induced liver injuries.

The antioxidant action of medicinal herbs used in Ghana for treating various ailments was evaluated in vitro and in vivo. Five plants, Desmodium adscendens, Indigofera arrecta, Trema occidentalis, Caparis erythrocarpus, and Thonningia sanguinea were tested for their free radical scavenging action by their interaction with 1,1-diphenyl-2-picrylhydrazyl (DPPH). Of these five plants, only Thonningia sanguinea was found to scavenge the DPPH radical. Lipid peroxidation in liver microsomes induced by H2O2 was also inhibited by T. sanguinea. The hepatoprotective effect of T. sanguinea was studied on acute hepatitis induced in rats by a single dose of galactosamine (GalN, 400 mg/kg, IP) and in mice by carbon tetrachloride (CCl4, 25 microl/kg, IP). GalN induced hepatotoxicity in rats as evidenced by an increase in alanine aminotransferase (ALT) and glutathione (GSH) S-transferase activities in serum was significantly inhibited when T. sanguinea extract (5 ml/kg, IP) was given to rats 12 hr and 1 hr before GalN treatment. The activity of liver microsomal GSH S-transferase, which is known to be activated by oxidative stress, was increased by the GaIN treatment and this increase was blocked by T. sanguinea pretreatment. Similarly, T. sanguinea pretreatment also inhibited CCl4-induced hepatotoxicity in mice. These data indicate that T. sanguinea is a potent antioxidant and can offer protection against GalN- or CCl4-induced hepatotoxicity.     

Inhibition of the renin-angiotensin system attenuates the development of liver fibrosis and oxidative stress in rats

1. The present study was designed to investigate the potential antifibrotic and anti-oxidant effects of lisinopril, fosinopril and losartan in an experimental rat model of liver injury using carbon tetrachloride (CCl(4)). 2. First, the potential hepatoprotective dose of each drug was screened against CCl(4)-induced acute hepatotoxicity. Then, we chose the minimum hepatoprotective dose of each drug to further investigate the mechanisms involved in the hepatoprotection using a chronic model of hepatotoxicity induced by CCl(4). 3. Liver function was assessed in addition to histopathological examination. Furthermore, oxidative stress markers (reduced glutathione (GSH) and lipid peroxides levels) and markers of fibrosis (hydroxyproline content and liver fibrosis area) were assessed. 4. It was found that treatment of animals with different drugs concomitantly with CCl(4) significantly counteracted the changes in liver function induced by CCl(4) (except fosinopril). In addition, the drugs ameliorated the histopathological changes induced by CCl(4). All drugs significantly counteracted lipid peroxidation and GSH depletion (except fosinopril) compared with the CCl(4)-intoxicated group. Moreover, the drugs studied significantly reduced liver hydroxyproline levels and the area of fibrosis compared with the CCl(4)-intoxicated group. 5. In conclusion, the present study provides evidence for the hepatoprotective effect of lisinopril, fosinopril and losartan. Both lisinopril and losartan was found to have better hepatoprotective potential than fosinopril against CCl(4)-induced hepatotoxicity. These hepatoprotective effects can be explained on the basis of anti-oxidant and antifibrotic mechanisms, mainly enhancement of GSH and reduction of lipid peroxidation and fibrosis.     

Evaluation of the antioxidant, anti-inflammatory and hepatoprotective properties of vanillin in carbon tetrachloride-treated rats

The antioxidant and anti-inflammatory effects of vanillin are considered as important forces in the protection against liver injury and fibrosis. This study investigated the protective effects of vanillin against carbon tetrachoride (CCl(4))-induced hepatotoxicity in rat. Pretreatment with vanillin prior the administration of CCl(4) significantly prevented the decrease of protein synthesis and the increase in plasma alanine (ALT) and aspartate (AST) aminotransferases. Furthermore, it inhibited hepatic lipid peroxidation (MDA) and protein carbonyl (PCO) formation and attenuated the (CCl(4))-mediated depletion of antioxidant enzyme catalase and superoxide dismutase (SOD) activities and glutathione level (GSH) in the liver. In addition, vanillin markedly attenuated the expression levels of pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) and prevented CCl(4)-induced hepatic cell alteration and necrosis, as indicated by liver histopathology. These findings suggest that the antioxidant and anti-inflammatory effects of vanillin against CCl(4)-induced acute liver injury may involve its ability to block CCl(4)-generated free radicals.     

Protective effect of boric acid against carbon tetrachloride-induced hepatotoxicity in mice

The protective effect of boric acid against liver damage was evaluated by its attenuation of carbon tetrachloride (CCl(4))-induced hepatotoxicity in mice. Male albino mice were treated intraperitoneally (i.p.) with boric acid (50, 100, and 200 mg/kg) or silymarin daily for 7 days and received 0.2% CCl(4) in olive oil (10 mL/kg, i.p.) on day 7. Results showed that administration of boric acid significantly reduced the elevation in serum levels of aspartate aminotransferase, alkaline phosphatase, alanine aminotransferase, and the level of malondialdehyde in the liver that were induced by CCl(4) in mice. Boric acid treatment significantly increased glutathione content, as well as the activities of superoxide dismutase and catalase in the liver. Boric acid treatment improved the catalytic activity of cytochrome P450 2E1 and maintained activation of nuclear factor kappa light-chain enhancer of activated B cell gene expression, with no effect on inducible nitric oxide synthase gene expression in the livers of mice. Histopathologically, clear decreases in the severity of CCl(4)-induced lesions were observed, particularly at high boric acid concentrations. Results suggest that boric acid exhibits potent hepatoprotective effects on CCl(4)-induced liver damage in mice, likely the result of both the increase in antioxidant-defense system activity and the inhibition of lipid peroxidation.     

Toxicological evaluation and hepatoprotective potential of Clerodendron glandulosum.Coleb leaf extract

This inventory evaluates toxicological effects and hepatoprotective potential of Clerodendron glandulosum.Coleb (CG) aqueous extract. Acute and subchronic toxicity tests were performed using Swiss albino mice as per the guideline of Organisation for Economic Cooperation and Development (OECD). Also, hepatoprotective potential of CG extract was examined in experimental model of carbon tetrachloride (CCl( 4))-induced hepatotoxicity. Acute and subchronic toxicity tests revealed that CG extract is non-toxic and its median lethal dose (LD(50)) value is >5000 mg/kg bodyweight. Also, rats pretreated with CG extract followed by administration of CCl(4) recorded significant decrement in plasma marker enzymes of hepatic damage, total bilirubin content and hepatic lipid peroxidation. While, hepatic reduced glutathione, ascorbic acid content, activity levels of superoxide and catalase and plasma total protein content were significantly increased. Microscopic examination of liver showed that pretreatment with CG extract prevented CCl(4)-induced hepatic damage in CG + CCl( 4) group. CG extract has hepatoprotective potential by modulating activity levels of enzymes and metabolites governing liver function and by helping in maintaining cellular integrity of hepatocytes that is comparable with that of standard drug silymarin. CG extract exhibits potent hepatoprotective activity against CCl(4)-induced hepatic damage but does not exhibit any toxic manifestations.     

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.     

Protective effects of total flavonoids of Bidens bipinnata L. against carbon tetrachloride-induced liver fibrosis in rats

Bidens bipinnata L. is well known in China as a traditional Chinese medicine and has been used to treat hepatitis in clinics for many years. In a previous study we found that total flavonoids of Bidens bipinnata L. (TFB) had a protective effect against carbon tetrachloride (CCl4)-induced acute liver injury in mice. Now this study was designed to investigate its therapeutic effect against CCl4-induced liver fibrosis in rats and to determine, in part, its mechanism of action. The liver fibrosis model was established by subcutaneous injection of 50% CCl4 twice a week for 18 weeks. TFB (40, 80 and 160 mg kg(-1)) was administered by gastrogavage daily from the 9th week. The results showed that TFB (80 and 160 mg kg(-1)) treatment for 10 weeks significantly reduced the elevated liver index (liver weight/body weight) and spleen index (spleen weight/body weight), elevated levels of serum transaminases (alanine aminotransferase and aspartate aminotransferase), hyaluronic acid, type III procollagen and hepatic hydroxyproline. In addition, TFB markedly inhibited CCl4-induced lipid peroxidation and enhanced the activity of the antioxidant enzymes superoxide dismutase and glutathione peroxidase. Moreover, TFB (80 and 160 mg kg(-1)) treatment improved the morphologic changes of hepatic fibrosis induced by CCl4 and suppressed nuclear factor (NF)-kappaB, alpha-smooth muscle actin (SMA) protein expression and transforming growth factor (TGF)-beta1 gene expression in the liver of liver fibrosis of rats. In conclusion, TFB was able to ameliorate liver injury and protect rats from CCl4-induced liver fibrosis by suppressing oxidative stress. This process may be related to inhibiting the induction of NF-kappaB on hepatic stellate cell activation and the expression of TGF-beta1.     

Effects of novel antioxidants on carbon tetrachloride-induced lipid peroxidation and toxicity in precision-cut rat liver slices

Previous studies in rat liver microsomes have demonstrated the effectiveness of the 21-aminosteroid, U-74,006F, the troloxamine, U-78,517G, and N,N'-diphenyl-p-phenylenediamine (DPPD) in preventing carbon tetrachloride (CCl4)-induced lipid peroxidation. Studies reported here utilized liver slices to assess whether these antioxidants could prevent lipid peroxidation and ensuing toxicity in a more complete/complex system. Liver slices prepared from Aroclor 1254-induced SD rats were incubated in Dulbecco's modified eagle media, 37 degrees C, for up to 9 hr. Slices were preincubated with test compounds for 30 min prior to addition of CCl4. Lipid peroxidation, as measured by the formation of thiobarbituric acid-reactive substances and ethane evolution, was decreased by U-74,006F (100 microM), U-78,517G (100 microM), and DPPD (1 microM). CCl4 (2.5 microliters) decreased intracellular K+ content, intracellular lactate dehydrogenase (LDH), and intracellular isocitrate dehydrogenase (ICD) activities over a 9-hr incubation period. Despite the marked effects on lipid peroxidation, U-74,006F showed no protection against K+ or LDH loss and only moderate protection against ICD loss. U-78,517G showed no protection against K+ loss but substantial protection against enzyme loss. DPPD demonstrated slight protection against K+ and marked protection against enzyme loss. All three compounds inhibited CCl4-induced lipid peroxidation; U-78,517G being most effective, followed by DPPD and U-74,006F. Inhibition of lipid peroxidation provided protection to the membrane structure as indicated by inhibition of LDH and ICD loss. The antioxidants failed to protect against CCl4-induced toxicity (K+ loss). These results suggest that CCl4-induced lipid peroxidation and toxicity may be dissociable.     

Protective effects of Pycnogenol on carbon tetrachloride-induced hepatotoxicity in Sprague-Dawley rats.

Oxidative damage is implicated in the pathogenesis of various liver injuries. In the present study the ability of Pycnogenol (PYC) as an antioxidant to protect against CCl4-induced oxidative stress and hepatotoxicity in rats was investigated. Four experimental groups of six rats each were constructed: a vehicle control group received the respective vehicles (distilled water and corn oil) only; a CCl4 group received a 14-day repeated intraperitoneal (i.p.) dose of distilled water and then a single oral dose of CCl4 at 1.25 ml/kg; and the CCl4&PYC 10 and CCl4&PYC 20 groups received a 14-day repeated i.p. dose of PYC 10 and 20 mg/kg, respectively, and then a single oral dose of CCl4 at 1.25 ml/kg. Hepatotoxicity was assessed 24 h after the CCl4 treatment by measurement of serum aminotransferase (AST) and alanine aminotransferase (ALT) activities, hepatic malondialdehyde (MDA) and glutathione (GSH) concentrations, and catalase, superoxide dismutase (SOD), and glutathione-S-transferase (GST) activities. The results were confirmed histopathologically. The single oral dose of CCl4 produced significantly elevated levels of serum AST and ALT activities. Histopathological examinations showed extensive liver injuries, characterized by extensive hepatocellular degeneration/necrosis, fatty changes, inflammatory cell infiltration, congestion, and sinusoidal dilatation. In addition, an increased MDA concentration and decreased GSH, catalase, SOD, and GST were observed in the hepatic tissues. On the contrary, PYC treatment prior to the administration of CCl4 significantly prevented the CCl4-induced hepatotoxicity, including the elevation of serum AST and ALT activities and histopathological hepatic lesions, in a dose-dependent manner. Moreover, MDA and GSH levels and catalase, SOD, and GST activities in hepatic tissues were not affected by administration of CCl4, indicating that the pretreatment of PYC efficiently protects against CCl4-induced oxidative damage in rats. The results indicate that PYC has a protective effect against acute hepatotoxicity induced by the administration of CCl4 in rats, and that the hepatoprotective effects of PYC may be due to both the inhibition of lipid peroxidation and the increase of antioxidant activity.     

Endotoxin pretreatment protects against the hepatotoxicity of acetaminophen and carbon tetrachloride: role of cytochrome P450 suppression

Bacterial endotoxin (lipopolysaccharide, LPS) is known to potentiate the toxicity of many hepatotoxicants. However, exposure to a sublethal dose of LPS renders animals tolerant to a lethal dose of LPS, and protects against the toxicity of some chemicals. This study was designed to examine the effects of LPS pretreatment on acetaminophen- and carbon tetrachloride (CCl(4))-induced liver injury in LPS-sensitive C3H/OuJ and LPS-resistant C3H/HeJ mice. Pretreatment of male C3H/OuJ mice with a single injection of LPS (0. 1 mg/kg, ip, for 24 h) protected against the hepatotoxic effects of acetaminophen (400 mg/kg) and carbon tetrachloride (CCl(4), 30 mg/kg), as indicated by serum alanine aminotransferase activity. In contrast, pretreatment of C3H/HeJ mice with 0.1 or 10 mg/kg LPS afforded no protection against the hepatotoxic effects of acetaminophen and CCl(4). In an attempt to determine the mechanism of LPS-induced protection against acetaminophen- and CCl(4)-induced hepatotoxicity in C3H/OuJ mice, liver cytochrome P450 was determined 24 h after LPS injection. LPS treatment caused a 26% decrease in total P450 content in C3H/OuJ but not in C3H/HeJ mice. CYP3A-catalized testosterone 6 beta-, 2 beta-, and 15 beta-hydroxylation was decreased 40% by LPS only in C3H/OuJ mice. To determine whether the differences to LPS-response in the two stains of mice is mediated by a strain-related difference in the release of cytokines, mice were pretreated with interleukin-1 (IL-1 alpha, 5 x 10(5) U/mouse), and the hepatoprotection and hepatic P450 enzymes were examined. IL-1 alpha pretreatment equally protected against the hepatotoxicity of acetaminophen and CCl(4) in both strains, and suppressed the total microsomal P450 and P450 enzyme-catalyzed testosterone hydroxylation to a similar extent. In conclusion, LPS pretreatment suppressed hepatic cytochrome P450 enzymes and protected against the hepatotoxicity of acetaminophen and CCl(4) in LPS-sensitive C3H/OuJ mice, but not in LPS-refractory C3H/HeJ mice. This protective effect of LPS appears to be mediated through the release of cytokines such as IL-1 alpha, which in turn suppresses the cytochrome P450 responsible for the activation of acetaminophen and CCl(4) to reactive metabolites.     

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.     

Dietary diacetylene falcarindiol induces phase 2 drug-metabolizing enzymes and blocks carbon tetrachloride-induced hepatotoxicity in mice through suppression of lipid peroxidation

Falcarindiol is a diacetylenic natural product containing unique carbon-carbon triple bonds. Mice were orally administrated falcarindiol (100 mg/kg), and drug-metabolizing and antioxidant enzymes were monitored in several tissues of mice. Treatment with falcarindiol was found to increase glutathione S-transferase (GST) and NAD(P)H: quinone oxidoreductase 1 activities in liver, small intestine, kidney, and lung. No changes were observed in cytochrome P450 (CYP) 1A known to activate procarcinogens. Western blot analysis revealed that various GST subunits including GSTA4, which plays an important role in the detoxification of alkenals produced from lipid peroxides, were induced in liver, small intestine, and kidney of falcarindiol-treated mice. Additionally, we investigated the protective effects of falcarindiol against hepatotoxicity induced by carbon tetrachloride (CCl(4)) and the mechanism of its hepatoprotective effect. Pretreatment with falcarindiol prior to the administration of CCl(4) significantly suppressed both an increase in serum alanine transaminase/aspartate transaminase (ALT/AST) activity and an increase in hepatic thiobarbituric acid reactive substance levels without affecting CCl(4)-mediated degradation of CYP2E1. Formation of hexanoyl-lysine and 4-hydroxy-2(E)-nonenal-histidine adducts, lipid peroxidation biomarkers, in homogenates from the liver of CCl(4)-treated mice was decreased in the group of mice pretreated with falcarindiol. These results suggest that the protective effects of falcarindiol against CCl(4) toxicity might, in part, be explained by anti-lipid peroxidation activity associated with the induction of the GSTs including GSTA4.     

The course of CCl4 induced hepatotoxicity is altered in mGSTA4-4 null (-/-) mice

Glutathione S-transferases (GSTs) play a key role in cellular detoxification of environmental toxicants through their conjugation to glutathione (GSH). Recent studies have shown that the alpha-class GSTs also provide protection against oxidative stress and lipid peroxidation (LPO). GSTA4-4 is a member of a sub group of the alpha-class GSTs. It has been shown to metabolize 4-hydroxynonenal (4-HNE) with high catalytic efficiency through its conjugation to glutathione (GSH) and has been suggested to be a major component of cellular defense against toxic electrophiles such as 4-HNE generated during LPO. Since the hepatotoxicity of carbon tetrachloride (CCl(4)) has been suggested to be due to the generation of free radicals leading to membrane LPO, the present studies were designed to compare hepatotoxicity of CCl(4) in GSTA4-4 null (-/-) and wild type (+/+) mice. The results show that administration of a single dose of CCl(4) (1 ml/kg i.p.) resulted in time dependent hepatotoxicity in both -/- and +/+ mice; the extent of cellular damage by serum enzymes suggests that progression was more rapid in -/- mice, although injury was similar by 24 h. Histopathologic examination showed similar degrees of centrilobular necrosis by 24 h but much greater surrounding degenerative change, including cellular swelling, disarray, and vacuolization, in the liver of -/- mice. As expected -/- mice did not show any expression of mGSTA4-4; after CCl(4) a compensatory increase in the activities of total GST activity was noted at 24 h. Major alterations in other antioxidant enzymes was not observed. 4-HNE levels in the liver of -/- mice were about four-fold higher than in +/+ mice, suggesting a positive correlation between 4-HNE levels and the altered course of CCl(4) hepatotoxicity. These studies suggest that GSTA4-4 is an important component during the early stages (1-6 h) of cellular defense against oxidative stress and LPO although, it is not effective in protecting against the ultimate degree of overall cell injury.     

Protective effect of saponins derived from the roots of Platycodon grandiflorum against carbon tetrachloride induced hepatotoxicity in mice

The purpose of this study was to investigate the protective effects of the saponins isolated from the root of Platycodi Radix (Changkil saponins: CKS) on carbon tetrachloride (CCl(4))-induced hepatotoxicities in mice. Pretreatment with CKS prior to the administration of CCl(4) significantly prevented the increase in serum alanine aminotransferase and aspartate aminotransferase activities and hepatic lipid peroxidation formation. In addition, CKS prevented CCl(4)-induced apoptosis and necrosis, as indicated by a liver histopathologic study and DNA laddering. To determine whether Fas/Fas ligand (FasL) pathway involved in CCl(4)-induced acute liver injury, Fas and FasL proteins and caspase-3, -8 activities were tested by western blotting and ELISA. CKS markedly decreased CCl(4)-induced Fas/FasL protein expression levels and in turn attenuated CCl(4)-induced caspase-3, -8 activities in mouse livers. Additionally, CKS protected the CCl(4)-induced depletion of hepatic glutathione levels. The effect of CKS on CYP2E1, the major isozyme involved in CCl(4) bioactivation, was investigated. Treatment with CKS resulted in a significant decrease in the CYP2E1-dependent hydroxylation of aniline. In addition, CKS exhibited antioxidant effects on FeCl(2)-ascorbate induced lipid peroxidation in liver homogenates, and on superoxide radical scavenging activity. These findings suggest that the protective effects of CKS against CCl(4)-induced acute liver injury possibly involve mechanisms related to its ability to block CYP2El-mediated CCl(4) bioactivation and its free radical scavenging effects, and that is also protects against Fas/FasL pathway mediated apoptosis.     

Effect of chitobiose and chitotriose on carbon tetrachloride-induced acute hepatotoxicity in rats

The purpose of the present study was to examine whether chitobiose and chitotriose can protect rats from CCl4-induced hepatic toxicity when given orally. We studied the effects of the 2 chitooligosaccharides given orally to rats on the acute hepatotoxicity induced by CCl4-dependent lipid peroxidation. The increase in the sum of malondialdehyde and 4-hydroxy-2-alkenals, a marker of lipid peroxidation, in both plasma and liver of CCl4-treated rats was suppressed by oral administration of chitobiose or chitotriose. The elevation in the levels of plasma aspartate transaminase and alanine transaminase activities, markers of hepatic injury, induced by CCl4 intoxication was also counteracted by oral administration of either chitooligosaccharide. The results indicate that chitobiose and chitotriose have the ability to exert a protective action against CCl4-induced acute hepatoxicity, probably by their antioxidant activity.     

Inhibition by the bioflavonoid ternatin of aflatoxin B1-induced lipid peroxidation in rat liver

Aflatoxin B1, a metabolite of Aspergillus flavus is a potent hepatotoxic and hepatocarcinogenic mycotoxin. Lipid peroxidation and oxidative DNA damage are the principal manifestations of aflatoxin B1-induced toxicity which could be mitigated by antioxidants. Many plant constituents, e.g. flavonoids, lignans and spice principles (capsaicin, curcumin, eugenol, etc.) have been reported to prevent liver damage associated with lipid peroxidation. In this study we investigated ternatin, a tetramethoxyflavone isolated from Egletes viscosa, for possible protection against liver injury induced by aflatoxin B1 in rats. Seventy two hours after a single intraperitoneal dose of aflatoxin B1 (1 mg kg(-1)), the concentration of malondialdehyde, the product of lipid peroxidation in liver homogenates, and serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were significantly elevated (P<0.001). Subcutaneous ternatin (25 mg kg(-1)) pretreatment greatly reduced aflatoxin B1-induced increases in the levels of serum enzymes (ALT from 5071+/-763 to 293+/-66 international units L(-1) and AST from 4241+/-471 to 449+/-108 international units L(-1)) and elevated malondialdehyde levels (from 11.37+/-1.27 to 0.79+/-0.22 nmol (mg wet tissue)(-1)) in a manner similar to oral vitamin E (300 mg kg(-1)), a standard antioxidant. Further, histological changes induced by aflatoxin B1 such as hepatocellular necrosis and bile-duct proliferation were markedly inhibited in animals pretreated with ternatin or vitamin E. These data provide evidence that ternatin inhibits lipid peroxidation and affords protection against liver damage induced by aflatoxin B1. Ternatin might, therefore, be a suitable candidate for the chemoprevention of aflatoxicosis associated liver cancer.     

Free radical scavenging and hepatoprotective actions of the medicinal herb, Crassocephalum crepidioides from the Okinawa Islands

Free radical scavenging and protective actions against chemically induced hepatotoxicity of Crassocephalum crepidioides were investigated. A water extract of C. crepidioides strongly scavenged superoxide anion, hydroxyl radical and also stable radical 1,1-diphenyl-2-picrylhydrazyl. Galactosamine (GalN, 400 mg/kg) and lipopolysaccharide (LPS, 0.5 microg/kg) induced hepatotoxicity of rats as seen by an elevation of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and of lipid peroxidation in liver homogenates was significantly depressed when the herbal extract was given intraperitoneally 1 and 15 h before GalN and LPS treatment. Similarly, carbon tetrachloride (CCl4) induced liver injury as evidenced by an increase in AST and ALT activities in serum was also inhibited by the extract pretreatment. Isochlorogenic acids, quercetin and kaempferol glycosides were identified as active components of C. crepidioides with strong free radical scavenging action. These results demonstrate that C. crepidioides is a potent antioxidant and protective against GalN plus LPS- or CCl4-induced hepatotoxicity.     

Mechanism of antihepatotoxic activity of atractylon, I: effect on free radical generation and lipid peroxidation1.

The mechanism of antihepatotoxic action of atractylon, a main sesquiterpenic constituent of ATRACTYLODES rhizomes, was studied. Atractylon inhibited carbon tetrachloride (CCl (4))-induced cytotoxicity in primary cultured rat hepatocytes and CCl (4)-induced lipid peroxidation by rat liver microsomes. However, atractylon increased the free radical generation by CCl (4) with rat liver microsomes in the presence of a radical trapping agent, phenyl T-butyl nitrone (PBN). In addition, atractylon generated free radical PER SE. Experiments using (13)CCl (4) instead of CCl (4) indicated that the increased free radicals consisted of those from (13)CCl (4) and from atractylon. Accumulated data support that although both CCl (4) and atractylon generate free radicals respectively by rat liver microsomes, free radical from CCl (4) conducts lipid peroxidation and produces liver lesion, while atractylon forms free radical which scavenges CCl (3) radical in the absence of PBN, inhibits lipid peroxidation by CCl (4) and suppresses CCl (4)-induced liver lesion.     

Hepatoprotective activity of berberine is mediated by inhibition of TNF-α, COX-2, and iNOS expression in CCl(4)-intoxicated mice

This study investigated the protective effects of isoquinoline alkaloid berberine on the CCl(4)-induced hepatotoxicity in mice. Berberine was administered as a single dose at 5 and 10mg/kg intraperitoneally (i.p.), 1h before CCl(4) (10%, v/v in olive oil, 2ml/kg) injection and mice were euthanized 24h later. The rise in serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) in CCl(4)-intoxicated mice was markedly suppressed by berberine in a concentration-dependent manner. The decrease in hepatic activity of superoxide dismutase (Cu/Zn SOD) and an increase in lipid peroxidation were significantly prevented by berberine. Histopathological changes were reduced and the expression of tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) was markedly attenuated by berberine 10mg/mg. The results of this study indicate that berberine could be effective in protecting the liver from acute CCl(4)-induced injury. The hepatoprotective mechanisms of berberine may be related to the free radical scavenging and attenuation of oxidative/nitrosative stress, as well as to the inhibition of inflammatory response in the liver.     

Mechanism investigation of dioscin against CCl(4)-induced acute liver damage in mice

The mechanisms of the ameliorating effects of dioscin against CCl(4) induced acute liver damage are investigated in this study. Dioscin significantly inhibited (p<0.01) the increases of serum ALT and AST activities compared with the CCl(4)-treated animals. The hepatic lipid peroxidation formation and, concentrations of TNF-α and IL-6 were also decreased. Liver histopathologic studies and a DNA laddering assay indicated that dioscin protected hepatocytes against CCl(4)-induced apoptosis and necrosis. Furthermore, dioscin decreased the protein expressions of Fas/FasL, increased Bcl-2/Bax ratio, inhibited the release of cytochrome c from mitochondrion to cytosol and attenuated CCl(4)-induced caspase-3 and -8 activities. The expressions of ICAM-1, vimentin, prohibitin, HGF, c-MET and GSTA1 were also regulated by dioscin and iNOS was also involved in the effects of this agent. These protective effects against CCl(4) induced acute liver damage might be through inhibiting lipid peroxidation, inflammatory cytokines, necrosis and apoptosis, and dioscin shows promise for development toward the treatment of acute chemically mediated liver injury.