Promethazine inhibits the formation of aldehydic products of lipid peroxidation but not covalent binding resulting from the exposure of rat liver fractions to CCl4

Reflections of an Aging Free Radical Part 2: Meeting Inspirational People

Significance: During my long career in the field of redox biology, I met many inspiring people, especially Lester Packer. Recent Advances: This special issue of Antioxidants & Redox Signaling is dedicated to Lester Packer. Critical Issues: In this short review, I explore how Lester and other pioneers helped to develop the redox biology field and how I interacted with them. Future Directions: In our research to advance the field of redox biology, we stand on the shoulders of giants, including Lester Packer.

Melatonin ameliorates oxidative stress and reproductive toxicity induced by cyclophosphamide in male mice

The present study evaluated the efficacy of melatonin in cyclophosphamide (CP)-induced testicular injury, lipid peroxidative damage, and antioxidant enzymes status of the mice testis on the basis of biochemical and histological studies. Mice were pretreated with four different doses of melatonin (2.5, 5, 10, and, 20 mg/kg by body weight (b.w.)) via intraperitoneal injection for five consecutive days followed by injection with CP (200 mg/kg b.w.) 1 h after the last injection of melatonin on the 5th day. After 24 h, mice were euthanized, testes were immediately removed, and biochemical and histological studies were conducted. Treatment with melatonin significantly mitigates lipid peroxidation, superoxide dismutase, and catalase activity and the level of reduced glutathione content abnormality induced by CP in mice testis. Histological examination clearly demonstrates that pretreatment of melatonin prevented CP-induced spermatogenesis toxicity and spermatogenic cells reduction in mice testis. The protective effect of melatonin is likely due to the antioxidative properties of the indolamine existed in the chemical structure. Because melatonin is a safe, natural compound, it could be used concomitantly as a supplement to protect people undergoing chemotherapy against reproductive toxicity.

Early pneumotoxic effects after oral administration of 1,2-dichloroethane

Early biochemical and histological changes in rat lungs were investigated after oral administration of 136 mg/kg 1,2-dichloroethane in oleum solution. The experiment was performed using 80 male Wistar rats. Bronchoalveolar lavage fluid and lung homogenate were examined on posttreatment days 1, 5, 15, and 30. In bronchoalveolar lavage fluid, the activities of lactate dehydrogenase, alkaline phosphatase, and acid phosphatase were elevated on day 1. The activities of superoxide dismutase, catalase, and glutathione peroxidase, and the content of malondialdehyde in lung homogenate, were also increased on day 1. The histological investigation indicated congestion, edema, and lung interstitial inflammatory changes. It was concluded that oral administration of 1,2-dichloroethane causes mild-to-moderate transitory toxic injury of the lung. Lipid peroxidation and the levels of key antioxidant enzymes are increased in the earliest posttreatment period.

Response of urinary lipophilic aldehydes and related carbonyl compounds to factors that stimulate lipid peroxidation in vivo

Peroxidation of lipids results in the formation of a number of aldehydic and other carbonyl-containing secondary degradation products. The effect of peroxidative stimuli mediated by vitamin E deficiency, a diet high in polyunsaturated fatty acids (containing cod liver oil), and carbon tetrachloride administration on urinary excretion of a number of lipophilic aldehydes and related carbonyl compounds was examined in rats. These secondary lipid peroxidation products were measured as 2,4-dinitrophenylhydrazine derivatives. All three treatments increased urinary excretion of secondary lipid peroxidation products, although the pattern of excretion of these products varied somewhat among the treatments. Significant increases were found in butanal, hexanal, octanal, butan-2-one, pentan-2-one, hex-2-enal, hepta-2,4-dienal, 4-hydroxyhex-2-enal, 4-hydroxyoct-2-enal, 4-hydroxynon-2-enal, and a number of unidentified carbonyl compounds. These results suggest that urinary excretion of these lipophilic secondary lipid peroxidation products is a useful and noninvasive marker of whole-body lipid peroxidation.

Studies on preventive and curative effects of berberine on chemical-induced hepatotoxicity in rodents

Berberis aristata is an edible plant employed in the South Asian Traditional Medicine, particularly its fruits being used as a tonic remedy for liver and heart. In this investigation, berberine, a known compound from this plant, was studied for its possible antihepatotoxic action in rats. Pretreatment of animals with berberine (4 mg/kg; orally twice daily for 2 days) prevented the acetaminophen- or CCl4-induced rise in serum levels of alkaline phosphatase (ALP) and aminotransaminases (AST and ALT), suggestive of hepatoprotection. Post-treatment with three successive oral doses of berberine (4 mg/kg every 6 h) reduced the hepatic damage induced by acetaminophen, while CCl4-induced hepatotoxicity was not modified, suggesting a selective curative effect against acetaminophen. Pretreatment of animals with a single oral dose of berberine (4 mg/kg) induced prolongation of the pentobarbital (60 mg/kg, i.p.)-induced sleeping time as well as increased strychnine (0.3 mg/kg; i.p.)-induced toxicity, suggestive of inhibitory effect on microsomal drug metabolizing enzymes, cytochrome P450s (CYPs).

Lipophilic aldehydes and related carbonyl compounds in rat and human urine

Rat and human urine samples were analyzed for lipophilic aldehydes and other carbonyl products of lipid peroxidation. The following compounds were identified as their 2,4-dinitrophenyl hydrazones by cochromatography with pure standards using three solvent systems: butanal, butan-2-one, pentan-2-one, hex-2-enal, hexanal, hepta-2,4-dienal, hept-2-enal, octanal, non-2-enal, deca-2,4-dienal, 4-hydroxyhex-2-enal, and 4-hydroxynon-2-enal. In general, fasted rats excreted less of these compounds than fed rats, indicating they were partially of dietary origin or that the endogenous compounds were excreted in a form not susceptible to hydrazone formation. The compounds excreted in human urine were similar to those excreted in rat urine but were present in lower concentrations. Identification of the conjugated forms of the lipophilic aldehydes and related carbonyl compounds excreted in urine may be a source of information about their reactions in vivo.

Paraquat-induced free radical reaction in mouse brain microsomes

Paraquat has been implicated as an environmental toxin which may induce the syndrome of Parkinson's disease after exposure to this agent. However, the biochemical mechanism by which paraquat causes cell death and neurodegeneration has not been extensively studied. Paraquat was rapidly taken up by nerve terminals isolated from mouse cerebral cortices. It induced lipid peroxidation in a concentration dependent manner in the presence of NADPH and ferrous ion. The maximal stimulation effect was obtained at a paraquat concentration around 100 microM and the Km value for paraquat was 46.7 microM. The lipid peroxidation required microsomal enzymes. Antioxidants, such as superoxide dismutase, catalase and promethazine significantly inhibited paraquat-induced lipid peroxidation. Due to its structural similarity to the pyridinium compound MPP+ (N-methyl-4-phenyl pyridium ion), it may be taken up by dopamine neurons and cause lipid peroxidation and cell death resulting in the manifestation of Parkinsonian syndrome.

C-methylated dihydrochalcones from Myrica gale L: effects as antioxidants and as scavengers of 1,1-diphenyl-2-picrylhydrazyl

A number of isomeric or chemically closely related C-methylated dihydrochalcones, which is a rare substance class, has been isolated from the fruit exudate of Myrica gale L. and subjected to the following tests: 1) inhibition of lipid peroxidation induced by tert-butyl hydroperoxide or bromotrichloromethane in isolated rat hepatocytes, 2) inhibition of peroxidation induced by Fe2+ ions in a cell free system with linolenic acid as substrate, 3) scavenging activity against the diphenylpicrylhydrazyl radical, and 4) inhibition of enzymatic lipid peroxidation in linoleic acid by soybean 15-lipoxy-genase. One of the compounds (myrigalone B = MyB; 2',6'-dihydroxy-4'-methoxy-3',5'-dimethyldihydrochalcone) showed good activity in all tests whereas the others were inactive or slightly active, except that myrigalone A (MyA; 3-(1-oxo-3-phenylpropyl)-1,1,5-trimethylcyclohexane-2,4,6-trione)) like its synthetic analogue MyA* (the polar part of MyA) was nearly as active as MyB in 4). The antioxidant properties of MyB are probably due to its radical scavenging activity and may be related to its conformation, which differs from that of the other compounds.

Preventive and curative effects of Artemisia absinthium on acetaminophen and CCl4-induced hepatotoxicity

1. Effect of aqueous-methanolic extract of Artemisia absinthium (Compositae) was investigated against acetaminophen- and CCl4-induced hepatic damage. 2. Acetaminophen produced 100% mortality at the dose of 1 g/kg in mice while pretreatment of animals with plant extract (500 mg/kg) reduced the death rate to 20%. 3. Pretreatment of rats with plant extract (500 mg/kg, orally twice daily for two days) prevented (P < 0.01) the acetaminophen (640 mg/kg) as well as CCl4 (1.5 ml/kg)-induced rise in serum transaminases (GOT and GPT). 4. Post-treatment with three successive doses of extract (500 mg/kg, 6 hr) restricted the hepatic damage induced by acetaminophen (P < 0.01) but CCl4-induced hepatotoxicity was not altered (P > 0.05). 5. Plant extract (500 mg/kg) caused significant prolongation (P < 0.05) in pentobarbital (75 mg/kg)-induced sleep as well as increased strychnine-induced lethality in mice suggestive of inhibitory effect on microsomal drug metabolizing enzymes (MDME). 6. These results indicate that the crude extract of Artemisia absinthium exhibits hepatoprotective action partly through MDME inhibitory action and validates the traditional use of plant in hepatic damage.

Characterization of the potential antioxidant and pro-oxidant actions of some neuroleptic drugs

It has been suggested in the literature that neuroleptic drugs may be able to exert antioxidant and/or pro-oxidant actions in vivo. The feasibility of this was tested by measuring the ability of chlorpromazine, prochlorperazine, metoclopramide, methotrimeprazine and haloperidol to scavenge biologically relevant oxygen-derived species in vitro. None of the drugs reacted with superoxide radical at a significant rate. Chlorpromazine, prochlorperazine, metoclopramide and methotrimeprazine were very powerful scavengers of hydroxyl radicals, reacting at almost a diffusion-controlled rate. Chlorpromazine showed some ability to inhibit iron ion-dependent hydroxyl radical formation. Chlorpromazine, methotrimeprazine, promethazine and prochlorperazine were powerful inhibitors of iron ion-dependent liposomal lipid peroxidation, scavengers of organic peroxyl radicals and inhibitors of haem protein/hydrogen peroxide-dependent peroxidation of arachidonic acid. Chlorpromazine, prochlorperazine, metoclopramide, methotrimeprazine and haloperidol were powerful scavengers of hypochlorous acid. Haloperidol showed no ability to inhibit lipid peroxidation or to scavenge peroxyl radicals, and reproducibly increased lipid peroxidation catalysed by haem proteins, in both the presence and absence of hydrogen peroxide. The relevance of these in vitro observations to events in vivo is discussed.

Prevention of carbon tetrachloride-induced lipid peroxidation in liver microsomes from dehydroepiandrosterone-pretreated rats

Dehydroepiandrosterone (DHEA), a lipid soluble steroid, administered to rats (100 mg/kg b.wt) by a single intraperitoneal injection, increases to twice its normal level in the liver microsomes. Microsomes so enriched become resistant to lipid peroxidation induced by incubation with carbon tetrachloride in the presence of a NADPH-regenerating system: also the lipid peroxidation-dependent inactivation of glucose-6-phosphatase and gamma-glutamyl transpetidase due to the haloalkane are prevented. Noteworthy, the liver microsomal drug-metabolizing enzymes and in particular the catalytic activity of cytochrome P450IIE1, responsible for the CCl4-activation, are not impaired by the supplementation with the steroid. Consistently, in DHEA-pretreated microsomes the protein covalent binding of the trichloromethyl radical (CCl3 degrees), is similar to that of not supplemented microsomes treated with CCl4. It thus seems likely that DHEA protects liver microsomes from oxidative damage induced by carbon tetrachloride through its own antioxidant properties rather than inhibiting the metabolism of the toxin.

Effect of alpha-tocopherol on hepatic mixed function oxidases in hepatic ischemia/reperfusion

This study was done to determine the relationship between microsomal lipid peroxidation during hepatic ischemia/reperfusion and alteration in cytochrome P-450-dependent drug metabolism. Rats were pretreated with alpha-tocopherol to inhibit lipid peroxidation or with vehicle (soybean oil) and then subjected to 60 min no-flow hepatic ischemia in vivo. Control animals were time-matched sham-ischemic animals. After 1, 5 or 24 hr of reperfusion, liver microsomes were isolated and cytochrome P-450 and mixed function oxidases were studied. In vehicle-treated ischemic rats, serum ALT levels peaked at 5 hr (5,242 +/- 682 U/L) and were significantly reduced by alpha-tocopherol pretreatment (1,854 +/- 229 U/L, p less than 0.01). Similarly, microsomal lipid peroxidation was elevated in the vehicle-treated ischemic group, but this elevation was prevented by alpha-tocopherol pretreatment. Microsomal cytochrome P-450 content and aminopyrine-N-demethylase activity were both decreased in vehicle-treated ischemic rats to 60% and 70% of sham-ischemic control levels, respectively. Although alpha-tocopherol restored cytochrome P-450 content to the level of sham-ischemic control rats, aminopyrine-N-demethylase activity remained at 76% of control with alpha-tocopherol treatment (p less than 0.01 compared with sham-ischemic control). In contrast to what was seen with cytochrome P-450 and aminopyrine-N-demethylase, aniline p-hydroxylase activity was elevated in the vehicle-treated ischemic rats compared with sham-ischemic control rats. These increases were prevented by alpha-tocopherol pretreatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipid peroxidation and irreversible cell damage: synergism between carbon tetrachloride and 1,2-dibromoethane in isolated rat hepatocytes

The combination of 1,2-dibromoethane (DBE) with carbon tetrachloride (CCl4) in the isolated rat hepatocyte model produces a significant potentiation of both lipid peroxidation and plasma membrane damage induced by the latter compound. The increase in malondialdehyde production precedes the hepatocyte damage, evaluated in terms both of lactate dehydrogenase leakage and trypan blue exclusion. When hepatocytes are isolated from vitamin E pretreated rats, both the prooxidant and the cytotoxic effects of CCl4 are prevented. Also the synergism between CCl4 and DBE on lipid peroxidation disappears completely while that on cell damage is strongly reduced. The increased lipid peroxidation appears to be one of the mechanisms of the observed synergism between CCl4 and DBE on hepatocyte damage. Regarding the antioxidant status of the hepatocyte challenged with CCl4 and DBE, an early and significant consumption of vitamin E is observed only in the presence of the mixture of these xenobiotics. Total nonprotein thiol content is not significantly modified by CCl4 poisoning while DBE, alone and in association with CCl4, markedly decreases it. Vitamin E supplementation does not prevent but moderately delays total nonprotein thiol depletion due to DBE or to the mixture. Finally, glutathione transferase activity is significantly reduced by CCl4 treatment and not by DBE, and vitamin E supplementation totally prevents such inhibition. The increased prooxidant effect of CCl4 plus DBE compared to CCl4 alone seems related to the shift in DBE metabolism consequent to the CCl4-dependent inactivation of glutathione transferase.

Menadione and cumene hydroperoxide induced cytotoxicity in biliary epithelial cells isolated from rat liver

Biliary epithelial cells (BEC) and parenchymal cells isolated from normal rat liver were exposed in vitro to a number of toxic compounds. BEC were found to be highly sensitive to concentrations of menadione (100 microM) and cumene hydroperoxide (10 microM) that are usually not effective as toxic agents in hepatocytes under normoxic conditions. On the other hand, BEC were not affected by concentrations of carbon tetrachloride or 7-ethoxycoumarin that are known to exert toxic effects on hepatocytes. The development of both menadione- and cumene hydroperoxide-induced toxic injury in BEC followed a common and time-correlated pattern, and included a strong depletion of GSH, depletion of protein thiols and an increase in the extent of cell death. The damage induced by cumene hydroperoxide was found to be independent of lipid peroxidative processes and was prevented by a pre-incubation with desferrioxamine. The cytotoxicity of menadione was further exacerbated by dicoumarol but was not prevented by desferrioxamine or promethazine. The mechanisms underlying BEC injury and death induced by the quinone and by the organic hydroperoxide are discussed in relation to the known biochemical characteristics of BEC.