Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.109 (AST)
 6,066 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the past decade it became accepted that free radicals, lipid peroxidation and antioxidant defense play a role in various tissues damages, thus in certain liver diseases as well. Since only limited data have been reported concerning the oxidative stress in viral hepatitis, a comparative study was performed in patients (pts) with chronic hepatitis C and alcoholic liver disease. In addition, the effects of a flavonolignan drug silymarin were assessed. 10 pts with chronic hepatitis C, 5 pts with alcoholic hepatitis and 13 pts with alcoholic cirrhosis have been investigated. Biochemical liver tests (serum bilirubin, aminotransferases, ALT, AST, lactate dehydrogenase (LDH), pseudocholinesterase, prothrombin), malandialdehyde (MDA) levels in plasma and red blood cell (RBC) hemolysate, superoxide radical generating capacity of stimulated polymorphonuclear granulocytes (PMN), plasma concentrations of reduced (GSH) and oxidized (GSSG) glutathione, vitamin A, luteine and beta carotene, furthermore RBC superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase activities were determined. The level of plasma MDA--as the marker of lipid peroxidation--was highest in alcoholic cirrhosis (five times of normal) (p < 0.05), the RBC hemolysate MDA was most elevated in chronic hepatitis C (p < 0.05). The mean PMNs' superoxide radical generating capacity was 116.6% of normal control in alcoholic hepatitis, where the mean GSH level was the lowest (89.8% of normal). Plasma vitamin A content was lowest in alcoholic cirrhosis (68% of control) (p < 0.05). SOD activity was elevated in both chronic hepatitis C and alcoholic cirrhosis, where GPx activity was decreased (p < 0.05). There was a correlation between LDH and SOD activities (r = 0.77, p = 0.015). Silymarin treatment of one month duration resulted in normalization of serum bilirubin in 55% of treated pts, AST became normal in 45%, and RBC hemolyzate MDA level normalized in similar rate. A significant increase in both GSH and retinoids was found. Alterations in oxidative stress and antioxidant defense system were shown in chronic hepatitis C, not only in alcoholic liver disease. The parameters of lipid peroxidation and antioxidant defense may be useful surrogate markers for monitoring pts with liver disease during hepatoprotective treatment.
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PMID:[Oxidative stress and antioxidant defense in alcoholic liver disease and chronic hepatitis C]. 1096 2

The hepatoprotective activity of the aqueous-methanolic extract of Ambrosia maritima was investigated against acetaminophen (paracetamol, 4-hydroxy acetanilide) induced hepatic damage. Acetaminophen at the dose of 640 mg/kg produced liver damage in rats as manifested by the significant (P < 0.001) rise in serum levels of glutamate oxaloacetate transaminase (AST), glutamate pyruvate transaminase (ALT) and alkaline phosphatase (ALP) to 1178.5 +/-118.05; 607.5 +/- 32.6 and 274.16 +/- 8.89 IU/l (n = 10), respectively, compared with respective control values of 97.83+/-3.23; 46.0 +/- 3.92 and 168.67 +/- 7.86 IU/l. Pretreatment of rats with the plant extract (100 and 200 mg/kg) lowered significantly (P < 0.001) the respective serum AST to 203.3+/-5.74 and 157.1 +/- 8.78 IU/l, ALT to 138.67 +/- 7.7 and 87.5 +/- 3.6 IU/l and ALP levels to 238.0 +/- 5.89 and 206.5 +/- 7.5 IU/l, respectively. Treatment of rats with acetaminophen led to a marked increase in lipid peroxidation as measured by malondialdehyde (MDA) (42%). This was associated with a significant reduction of the hepatic antioxidant system e.g. reduced glutathione (GSH) (65%), glutathione reductase (GSH-R) (35%), total glutathione peroxidase (GSH-Px) (32%) and glutathione-S-transferase (GST) (16%). These biochemical alterations resulting from acetaminophen administration were inhibited by pretreatment with A. maritima L. extract. These data suggest that the plant A. maritima L. may act as a hepatoprotective and antioxidant agent.
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PMID:Evaluation of the protective potential of Ambrosia maritima extract on acetaminophen-induced liver damage. 1129 46

The iron chelating activity of deferoxamine (DFO) has been exploited to obtain protection against the peroxidative damage in rat heart which was induced by the administration of an acute dose of doxorubicin (DXR, 25 mg x kg(-1), i.v.). The peroxidative lesions were evaluated both biochemically and histopathologically, 48 h after DXR administration. Abnormal biochemical changes including a marked increase in the levels of serum creatine kinase isoenzyme (CK-MB), and lactate dehydrogenase (LDH), as well as elevated serum creatinine, blood urea nitrogen and transaminases (ALT and AST) levels were observed. Myocardial tissue from DXR treated rats showed a marked increase in malondialdehyde (MDA) production and depletion of reduced glutathione (GSH) contents. Similar results were also observed in both kidney and liver tissues. Pretreatment of rats with DFO, given i.p. 30 min prior to DXR injection, substantially reduced the peroxidative damage in the myocardium, hepatic and renal tissues and markedly lowered the serum CK-MB, LDH and the other biochemical variables. The protective effects obtained by DFO administration, however, were not complete and did not reach those of the control group. The significant protection against DXR-induced cardiomyopathy by DFO was evident from the histopathological findings observed by light microscopy. DFO at a dosing level equivalent to 10-fold of that of DXR was useful to obtain protective effects. Higher DFO dosing levels did not, however, show more improvement in the DXR-induced cardiotoxicity and at the same time exhibited hepatoxicity which was confirmed by microscopical examination. These results strongly suggest that DFO protects against acute DXR-induced cardiotoxicity in a dose-dependent manner with recognizing the presence of mild DFO-related biochemical and cytological hepatic toxicity.
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PMID:The preventive role of deferoxamine against acute doxorubicin-induced cardiac, renal and hepatic toxicity in rats. 1140 11

Tobacco smoke is involved in the pathogenesis of several diseases regarding different body systems, mainly cardiovascular and respiratory in addition to its local toxic effect in the oral cavity. The noxious effects of smoke compounds justify the high incidence of periodontal diseases, caries, and neoplastic diseases of oral tissues in smokers. Some toxic components of tobacco smoke, unsaturated and saturated aldehydes, could interact with thiol rich compounds, leading to structural and functional modification of these molecules. Previous papers have demonstrated an in vitro significant decrease of some enzymatic activities, both in plasma and in saliva, following external addition of aldehydes or exposure to cigarette smoke (CS). Furthermore, the same studies underlined the protective effect exerted by the addition of glutathione (GSH) against the damaging role of smoke aldehydes. In this study some salivary enzymes (lactic dehydrogenase [LDH], aspartate aminotransferase [AST] and amylase), and total GSH were measured in 20 volunteers smokers, before and just after smoking a single cigarette. All enzymatic activities showed a significant inhibition following a single cigarette, probably due to the interaction between smoke aldehydes and -SH groups of the enzyme molecules. Moreover, the percentage of the enzymatic inhibition showed a negative correlation with the basal level of salivary GSH. Our results emphasize that not only one cigarette is sufficient to impair the salivary enzymatic activities but also strengthen the proposed protective role of GSH against the noxious biochemical effects of CS.
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PMID:Inhibition of salivary enzymes by cigarette smoke and the protective role of glutathione. 1204 26

The present investigation focused on the possible hepatoprotective potential of captopril on carbon tetrachloride (CCl4)-induced acute liver injury in mice. Twenty-four hours after a single intraperitoneal injection of CCl4 (20 microl/Kg), hepatotoxicity was evidenced in the serum by elevated levels of aspartate transaminase (AST; EC: 2.6.1.1), alanine transaminase (ALT; EC: 2.6.1.2) and lactate dehydrogenase (LDH; EC: 1.1.1.27) and in the liver by depleted level of reduced glutathione (GSH), enhanced activity of glutathione peroxidase (GSH-Px; EC: 1I.11.1.9) and elevated level of lipid peroxides (LP). Captopril was given orally at three dose levels viz., 10, 25 and 50 mg/Kg/day for three consecutive days before subjecting the animals to the hepatotoxin. With the exception of the lowest dose namely, 10 mg/Kg/day, captopril afforded protection against CCl4-induced hepatotoxicity to different extents. Thus, the elevated activities of the enzymes AST, ALT, LDH and GSH-Px as well as the enhanced lipid peroxidation were markedly reduced below those elicited by the hepatotoxin, reaching values closer to the control, though still statistically higher. Captopril, however, did not ameliorate the depletion of GSH produced by CCl4. The data reported herein reveal a protective potential of captopril against the acute hepatotoxicity induced by CCl4 in mice. This hepatoprotection could be attributed, at least in part, to the free radical scavenging properties of the drug.
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PMID:Prior treatment with captopril attenuates carbon tetrachloride-induced liver injury in mice. 1209 Mar 55

The radioprotective effect of silymarin using different modes of treatment against radiation (3 or 6 Gy) induced hepatotoxicity 1, 3 and 7 days post-irradiation was studied. Whole-body gamma-irradiation revealed an increase in serum alkaline phosphatase (AP) activity as well as liver glutathione reductase (GR) and glutathione peroxidase (GSH-PX) activities on the first post-exposure day with respect to the control value. However, 3 days after radiation exposure, these parameters showed a significant decrease below the control level which persisted till the end of the experimental time except for serum AP activity that showed another increase on the seventh post-exposure day at 3 Gy dose of radiation. A gradual increase in serum alanine and aspartate aminotransferase (ALT&AST) as well as gamma glutamyl transpeptidase activities were observed due to irradiation throughout the experimental time. Administration of silymarin as single (70 mg kg (-1)), fractionated (490 mg kg (-1)) oral doses or as intravenous (i.v.) injection (50 mg kg (-1)), caused significant protection. Intravenous treatment showed the most pronounced protection. The protective effect of silymarin was attributed to its antioxidant and free radicals scavenging properties.
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PMID:Radioprotective effect of silymarin against radiation induced hepatotoxicity. 1216 44

In order to study sub-acute hepatotoxicity of low doses of microcystins in vivo, as well as to understand the mechanisms of hepatotoxicity of microcystins, eighty Spague-Dawley rats were injected with microcystins intraperitoneally at the doses of 0, 4, 8 and 12 micrograms.(kg.d)-1, respectively, for 35 days. Then blood and liver samples were used for assay. Several enzymatic levels and pathological changes were detected. Both terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) and immunohistochemical methods were employed to study the apoptosis and proliferating cell nuclear antigen (PCNA). It was shown that the activity of serum gamma-glutamyltransferase (GGT) and concentrations of whole blood glutathione (GSH) decreased, serum activities of lactate dehydrogenase (LDH) and aminotransferase (AST) increased after exposure to MC. No significant change of concentration of serum alanine aminotransferase (ALT) was observed in the tested groups. Characteristic morphological alterations and active proliferation as well as apoptosis of hepatotocytes were observed in the treated groups. It was suggested that oxidative injury and apoptosis of hepatocytes induced by microcystins may be the mechanisms of its hepatotoxicity.
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PMID:[Sub-acute hepatotoxicity of low doses of microcystins]. 1253 25

Ischemic preconditioning (IP) triggers protection of the liver from prolonged subsequent ischemia. However, the underlying protective mechanisms are largely unknown. We investigated whether and how IP protects the liver against reperfusion injury caused by Kupffer cell (KC)-derived oxidants. IP before 90 minutes of warm ischemia of rat livers in vivo significantly reduced serum alanine aminotransferase (AST) levels and leukocyte adherence to sinusoids and postsinusoidal venules during reperfusion. This protective effect was mimicked by postischemic intravenous infusion of glutathione (GSH), an antioxidative strategy against KC-derived H(2)O(2). Interestingly, no additional protection was achieved by infusion of GSH to preconditioned animals. These findings and several additional experiments strongly suggest IP mediated antioxidative effects: IP prevented oxidant cell injury in isolated perfused rat livers after selective KC activation by zymosan. Moreover, IP prevented cell injury and pertubations of the intracellular GSH/GSSG redox system caused by direct infusion of H(2)O(2) (0.5 mmol/L). IP-mediated resistance against H(2)O(2) could neither be blocked by the adenosine A2a antagonist DMPX nor mimicked by A2a agonist CGS21680. In contrast, H(2)O(2) resistance was abolished by the p38 mitogen-activated protein kinase (p38 MAPK) inhibitor SB203580, but induced when p38 MAPK was directly activated by anisomycin. In conclusion, we propose a novel concept of hepatoprotection by IP: protection of liver cells by enhancing their resistance against KC-derived H(2)O(2). Activation of p38 MAPK and preservation of the intracellular GSH/oxidized glutathione (GSSG) redox system, but not adenosine A2a receptor stimulation, seems to be pivotal for the development of H(2)O(2) resistance in preconditioned livers.
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PMID:Induction of cellular resistance against Kupffer cell-derived oxidant stress: a novel concept of hepatoprotection by ischemic preconditioning. 1254 Jul 78

The aim of this study was to investigate the protective effect of honokiol and magnolol on hepatocyte injury induced by either tertiary butyl hydroperoxide (tBH)- or D-galactosamine (GalN). The cellular leakage of LDH and AST, and cell death by treatment with 1.5 mM tBH for 1 h, were significantly inhibited by treatment with honokiol (40 and 20 microM) or magnolol (40 microM). Treatment with honokiol or magnolol significantly inhibited lipid peroxidation in both cells and media, the generation of intracellular reactive oxygen species (ROIs), and intracellular glutathione (GSH) depletion induced by tBH. The cellular leakage of LDH and AST, and cell death, by 24-hour treatment with 30 mM GalN were significantly inhibited by treatment with honokiol (20, 5 and 1 microM) or magnolol (20, 5 and 1 microM). Treatment with honokiol (20, 5 and 1 microM) or magnolol (20 and 5 microM) significantly inhibited the intracellular GSH depletion induced by GalN. The hepatoprotective effects of honokiol and magnolol on oxidative stress induced by tBH were probably the result of their antioxidant activity. Honokiol and magnolol also had a protective effect against GalN-induced hepatotoxicity, which was used as an alternate model to oxidative stress, acting by inhibiting intracellular GSH depletion.
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PMID:Protective effects of honokiol and magnolol on tertiary butyl hydroperoxide- or D-galactosamine-induced toxicity in rat primary hepatocytes. 1256 76

The effect of N-acetylcysteine (NAC) (Ig/kg body weight in saline for 7 days) against the damages induced by gamma ray was studied. Whole body exposure of rats to gamma-rays (3.5 Gy) caused increases in lipid peroxides (P < 0.01). Reduced glutathione (GSH) (P < 0.01) and total sulphydryl groups (TSH) (P < 0.05), were found to be increased probably to counteract the damages produced by the lipid peroxides. The plasma antioxidant vitamins E, C and A were reduced. The activities of antioxidant enzymes, superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) were enhanced, which might be to eliminate the superoxide radical and H2O2 and accompanied by a fall in glutathione-s-transferase (GST) and glutathione reductase (GR) activity. The excessive production of free radicals and lipid peroxides might have caused the leakage of cytosolic enzymes such as aminotransferases (AST and ALT), lactate dehydrogenase (LDH), creatine kinase (CK) and phosphatases. Membrane damage is quite evident from histological studies undertaken in the intestinal tissue, which is susceptible to radiation damage. Intragastric pretreatment of NAC (1g/kg body weight in saline for 7 days) prevented the radiation induced damage to an appreciable extent. From the results it may be concluded that NAC is effective in protecting from the damages caused by gamma-ray radiations and its prospects as an adjuvant to radiotherapy should be considered.
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PMID:Protective effect of N-acetylcysteine against gamma ray induced damages in rats--biochemical evaluations. 1262 81


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