Paracetamol-induced Lipid Peroxidation Research Articles

The impact of vitamin C on the relationship among inflammation, lipid peroxidation and platelet activation during analgesic nephropathy in rats.

Oxidative stress and inflammation are involved in the pathogenesis of paracetamol-induced renal damage. This study examines the relationship between 8-iso-prostaglandin F2α (8-iso-PGF2α) and platelet activation as well as the relative contribution of the pro-inflammatory markers interleukin (IL)-1β and tumor necrosis factor-α (TNF-α) in enhanced 8-iso-PGF2α biosynthesis, as a complementary onset during analgesic nephropathy induced by chronic treatment with paracetamol. The protective effects of vitamin C on the aforementioned settings are also investigated. Analgesic nephropathy was induced in Wistar rats. Renal function markers and the activity of antioxidant enzymes were determined spectrophotometrically. Immunoassays were used to measure the pro-inflammatory markers and the markers of lipid peroxidation and platelet activation. The chronic treatment with paracetamol led to renal dysfunction, represented by the elevation of plasma urea and creatinine and the decline in the enzymatic antioxidant status, but did not cause a significant increase in TNF-α and IL-1β. The paracetamol-induced lipid peroxidation and enhanced production of 8-iso-PGF2α was not sufficient to cause changes in platelet activation represented by the level of 11-dehydro thromboxane B2. Our results suggest that oxidative stress cannot circumvent the need of stimulation by circulatory cytokines in order to induce inflammatory response and changes in platelet activation during analgesic nephropathy. Vitamin C proved to be beneficial in restoring the renal function markers to normal, increasing the renal enzymatic antioxidant potential, inhibiting lipid peroxidation, and lowering cytokine production and 11-dehydro thromboxane B2 excretion. The observed effects of vitamin C offer support for its potential use as protective treatment in cases of chronic paracetamol overdose.

Evaluation of hepatoprotective activity of abelmoschus moschatus seed in paracetamol induced hepatotoxicity on rat

Paracetamol (PCM) is widely used as analgesic and antipyretic drug, but at high dose it leads to undesirable side effects, such as hepatotoxicity. This study gives the information about hepatoprotective activity of abelmoschus moschatus seed extract against paracetamol and ethanol induced hepatotoxicity. Paracetamol induce hepatotoxicity was evaluated by an increase (P<0.05) in serum AST, ALT, ALP activity and bilirubin level Paracetamol hepatotoxicity was manifested by an increase (P<0.05) lipid peroxidation, depletion of reduced glutathione (GSH) and catalase activity in liver tissue. Administration of etanolic as well as aqueous plants extract [300mg/kg body weight of rat] protects the paracetamol induced lipid peroxidation, restored altered serum marker enzymes and antioxidant level towards normal. The results indicate hepatoprotective activity of all studied plants extract against paracetamol induced toxicity. Ethanolic extract was found more significant than the aqueous extract.

Antioxidant and hepatoprotective effects of the methanol extract of the leaves ofSatureja macrostema

Satureja Macrostema is used both as a functional food and as a drug. In this study, the antioxidative potential of the methanol extract of Satureja Macrostema (SM) was evaluated using various antioxidant assays, including DPPH, superoxide, nitric oxide (NO), hydroxyl radical scavenging and iron-chelating activity. Total phenolic and flavonoid content of SM was also determined by a colorimetric method. The extract exhibited powerful free radical scavenging, especially against DPPH, hydroxyl radical scavenging and iron-chelating activity as well as a moderate effect on NO and superoxide anions. The protective effects of methanol extract of SM were studied in carbon tetrachloride-reduced biochemical markers of hepatic injury such as glutamate pyruvate transaminase (SGPT), serum glutamate oxalaoacetate transaminase (SGOT), alkaline phosphatase (ALP), serum bilirubin, cholesterol alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. The increased level of HDL demonstrated dose dependant reduction in the in vivo peroxidation induced by CCl4. SM could protect from paracetamol-induced lipid peroxidation eliminating the deleterious effects of toxic metabolites from paracetamol. Degree of protection was measured by using biochemical parameters such as serum transaminase (GOT and GPT), alkaline phosphatase (ALKP) and bilirubin. Hexane and chloroform extracts did not show any effects. Results obtained in the present study suggest that S. Macrostema elicits hepatoprotectivity through antioxidant activity on carbon tetrachloride- and paracetamol-induced hepatic damage in rats.

Protective Role of Raphanus Sativus Root Extract on Paracetamol-Induced Hepatotoxicity in Albino Rats

The methanol extract of Raphanus sativus root extract showed a protective effect on paracetamol-induced hepatotoxicity in a dose-dependent manner. Degree of lipid peroxidation caused by paracetamol was measured in terms of thiobarbituric acid reactive substances (TBARS) and protection was measured in reference to serum glutamate oxaloacetate transaminase (SGOT), serum glutamate aspartate transaminase (SGPT), and blood and hepatic levels of antioxidants like glutathione and catalase. Administration of extract along with paracetamol showed significant protection. Levels of TBARS were found to be low, activities of SGOT and SGPT were low, while hepatic glutathione levels were significantly higher in experimental rats that received the mixture of paracetamol and the extract as compared to rats that received paracetamol only. Activities of catalase were also high in all experimental groups. Thus this study indicates the involvement of Raphanus sativus root extract with antioxidants like glutathione and catalase in rendering protection against paracetamol-induced lipid peroxidation and hepatotoxicity.

Cytotoxic and cytoprotective activities of curcumin: Effects on paracetamol-induced cytotoxicity, lipid peroxidation and glutathione depletion in rat hepatocytes

The cytoprotective effect of curcumin, a natural constituent of Curcuma longa, on the cytotoxicity of paracetamol in rat hepatocytes was studied. Paracetamol was selected as a model-toxin, since it is known to be bioactivated by 3-methylcholanthrene inducible cytochromes P450 presumably to N-acetyl- p-benzoquinone imine (NAPQI), a reactive metabolite which upon overdosage causes protein- and non-protein thiol-depletion, lipid peroxidation and cytotoxicity measured as LDH-leakage. At low concentrations curcumin was found to protect significantly against paracetamol-induced lipid peroxidation, without protection against paracetamol-induced LDH-leakage and without protection against paracetamol-induced GSH-depletion. At a 100 times higher concentration of curcumin the observed protective effect on lipid peroxidation was accompanied with a tendency to increase cellular GSH-depletion and LDH-leakage. No time-dependency was found as to the curcumin-induced effects: treatment of the hepatocytes 1 hr before, concomitantly or 1 hr after the addition of paracetamol to the cells had similar effects. In contrast to what was expected on the basis of previous in vivo experiments, at higher concentrations curcumin itself was found to be slightly cytotoxic. Curcumin-induced LDH-leakage was accompanied by a significant depletion of GSH. It has been concluded that the observed cytoprotective and cytotoxic activities of curcumin may be explained by a strong anti-oxidant capacity of curcumin and the capability of curcumin to conjugate with GSH. Furthermore, it has been concluded that lipid peroxidation is not playing a causal role in cell-death induced by paracetamol or by curcumin.

Effect of iron overload on spontaneous and xenobiotic-induced lipid peroxidation in vivo.

To study the effect of iron-overload on hepatic lipid peroxidation, two rat models of haemochromatosis were employed: in the first model resembling secondary haemochromatosis, repeated i.p. injections with Fe-dextran led to an accumulation of Fe in Kupffer cells, while in the second model resembling hereditary haemochromatosis, iron was located mainly in periportal hepatocytes after feeding on a diet containing 3.5% Fe-fumarate for 3 weeks. In both models, total hepatic iron content was elevated four- to fivefold over controls. In vivo lipid peroxidation (ethane exhalation) was enhanced only in the second model, indicating that the hepatocytes are the main targets of Fe-induced lipid peroxidation. Low hepatotoxicity was observed in the second model. Additional treatment of the rats with hepatotoxic agents led to different results: with ethanol and bromobenzene, lipid peroxidation was only evident in both models of iron-overload, while paracetamol-induced lipid peroxidation was seen only in Fe-fumarate-fed rats. CCl4-induced lipid peroxidation was strongly enhanced in both models of haemochromatosis. Hepatotoxicity was enhanced by iron overload only in the case of CCl4-treated, Fe-fumarate-fed rats. The activities of phase I and phase II enzymes of xenobiotic metabolism were not markedly altered in livers of iron-overloaded rats. This implies that neither the bioactivation nor the detoxification of the agents studied were affected in experimental haemochromatosis.

Paracetamol-stimulated lipid peroxidation in isolated rat and mouse hepatocytes

Treatment of isolated hepatocytes from 3-methylcholanthrene induced rats with 1 mM paracetamol has been found to greatly decrease cellular reduced glutathione (GSH) content and to promote lipid peroxidation, evaluated as malonaldehyde (MDA) production and conjugated diene absorbance. A similar dosing of hepatocytes from phenobarbital-induced or normal rats is ineffective in that respect. On the other hand, the aspecific stimulation of the cytochrome P-450-mediated paracetamol activation due to acetone addition further increases GSH depletion as well as MDA production. Isolated hepatocytes with basal low GSH content are also more susceptible to paracetamol-induced lipid peroxidation, indicating that the rate of the drug metabolism and the cellular GSH content are critical factors in the determination of such peroxidative attack. In isolated mouse liver cells paracetamol does not require preliminary cytochrome P-450 induction to stimulate MDA formation, even at concentrations ineffective in rat cells. However, 5 mM paracetamol, despite a great depletion of cellular GSH content, does not promote MDA formation either in the rat or in the mouse hepatocytes. This effect may be due to the ability of paracetamol to scavenge lipid peroxides under defined conditions, as tested in various lipid peroxidizing systems. Membrane leakage of lactate dehydrogenase (LDH) is evident in paracetamol treated cells undergoing lipid peroxidation, but not when MDA formation is inhibited by high doses of the drug or by addition of antioxidants such as α-tocopherol and diphenylphenylenediamine (DPPD). Nevertheless in these conditions the covalent binding of activated paracetamol metabolites is not affected, suggesting that lipid peroxidation might play a role in the pathogenesis of liver damage following paracetamol overdose.

Effect of old age on paracetamol-induced lipid peroxidation in rat liver

Post-mitochondrial supernatants isolated from the livers of mature rats (3 to 6 months old) 2 h or more after the administration of a single large oral dose of paracetamol (800 mg/kg) showed rapid rates of lipid peroxidation when incubated in vitro. In similar experiments with old rats (27–30 months old) the time between administration of paracetamol and the onset of lipid peroxidation was much longer (6 h or more). In both age groups, lipid peroxidation was dependent on the depletion of glutathione from the liver.

Studies on paracetamol-induced lipid peroxidation

Post-mitochondrial supernatants isolated from livers of rats given a single large oral dose of paracetamol (800 mg/kg) showed rapid rates of lipid peroxidation when incubated in vitro. As a result of paracetamol administration the level of reduced glutathione (GSH) declined to approx. 20–25% of the peak physiological value. Addition of reduced GSH to the supernatant inhibited the peroxidation. Paracetamol-induced lipid peroxidation was inhibited in vitro by antioxidants (e.g. vitamin E) but was unaffected by superoxide dismutase and mannitol. N-acetyl cysteine and cysteamine inhibited lipid peroxidation in vitro in a cytosol-dependent manner in the absence of glutathione. Lipid peroxidation probably occurs simultaneously with the proposed covalent binding of the active metabolite of paracetamol. Since the former process is known to cause severe and extensive membrane damage, it may be a very important factor in paracetamol-induced liver necrosis.

Drug-induced lipid peroxidation in mice—I Modulation by monooxegenase activity, glutathione and selenium status

Feeding male mice for 2 days with sucrose leads to a decrease of total liver glutathione by more than 50 per cent when compared to controls. Such animals were intoxicated with 300 mg/kg paracetamol and upon administration of inducers of the drug-metabolizing system, in vivo and vitro lipid peroxidation in these animals was largely increased as well as the susceptibility to the drug. Pretreatment of the mice with methylcholanthrene led to a 28-fold, with benzo(α)pyrene to a 22-fold, and with phenobarbital to a tenfold increase in ethane exhalation. In vivo administration of various monooxygenase inhibitors showed that all agents effectively inhibit paracetamol-induced lipid peroxidation. It is concluded that phase I metabolism of paracetamol is a prerequisite for the manifestation of drug-induced lipid peroxidation. Selenium deficiency in mice neither affected hepatic levels of glutathione nor its decrease following sucrose feeding, nor glutathione transferase, superoxide dismutase, catalase and glutathione reductase activity. Selenium-dependent glutathione peroxidase activity of selenium-deficient mice, reactive with H 2O 2 as well as with t-butylhydroperoxide, decreased to 5 per cent of the supplemented controls. A glutathione peroxidase activity, which utilized cumenehydroperoxide as a substrate but insensitive to selenium deficiency, was found. Selenium-deficient diethylmaleate-pretreated animals were much more susceptible to paracetamol-induced lipid peroxidation than controls. Supplemented diethylmaleate-pretreated animals showed no signs of lipid peroxidation if treated with 100 mg/kg aminopyrine or ethylmorphine. However, deficient animals exhibited high ethane exhalation rates, drastically increased serum transaminases, loss of hepatic glutathione and mortality upon administration of these drugs. Qualitatively similar results with lower ethane exhalation rates were observed when 125 mg/kg furosemide was administered to diethylmaleate-pretreated selenium-deficient or -adequate mice. Even administration of 200 mg/kg ethoxycoumarin in combination with diethylmaleate lead to significant lipid peroxidation in phenobarbital-induced mice. The results demonstrate that in vivo selenium-dependent glutathione peroxidase plays a predominant role within the glutathione redox couple system. The enzyme protects the liver from peroxidative damage evoked by phase I metabolism of various drug types, as long as sufficient glutathione is available. It is suggested that activated oxygen released from the microsomal monooxygenase is the species responsible for the observed lipid peroxidation accompanied by severe acute liver lesions.