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At least 1,243 records · Page 69Linked to original sources
PubMed1990

[Effect of mercuric chloride on phospholipid peroxidation in rat].

Individual molecular species of mercuric chloride induced phospholipid peroxide formed in rat brain, liver and kidney were determined using the multi-channel UV-high-performance liquid chromatography (HPLC) combined with potentiometric determination. Mercuric chloride (0.5 mg/kg/day) was administered subcutaneously to rats for 3 days. In accordance with a specified time schedule following administration (0.5, 1, 3 and 5 days), rats were decapitated and the phospholipids of brains, livers and kidneys were extracted and purified. The samples were then injected into the HPLC and the ratio (235 nm/203 nm) of peak area of each phospholipid was calculated. The peroxide value of each sample was determined using the calibration curve of the auto-oxidized standard phospholipids which were analyzed by both potentiometric determination and UV HPLC. Kidney phospholipid peroxides were easier induced than those in other organs reached their maximum peak (20.5 meq./kg) at 1 day after initial administration. Phospholipid peroxides in kidney and brain showed similar movement, while those in liver showed their maximum peak 3 days later. Of the phospholipids, phosphatidylserine and phosphatidylethanolamine seemed to be more susceptible to lipid peroxidation induced by mercuric chloride, the common feature of these two phospholipids being that both of them have primary amine group(s) on their polary heads and both are located on the cytosolic side of cell membrane. These results may be explained by mechanisms that relate to the interaction between mercurials and cell membranes or that between mercurials and primary amine groups of phospholipids. Further study is necessary to clarify the specific mechanisms involved in the induction of lipid peroxidation by mercurials and the interaction of mercurials with phospholipids.

Animals↗
PubMed1987

MPTP potentiates iron-induced lipid peroxidation without the involvement of free radicals derived from oxygen.

We demonstrate here that MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) potentiates iron-catalyzed lipid peroxidation in intact erythrocytes, whereas it does not mediate hydrogen peroxide catalysed lipid peroxidation. The malonaldehyde formation which results from this lipid peroxidation is generated in the absence of superoxides, hydroxyl radicals, hydrogen peroxide or singlet oxygen. The MPTP reaction is blocked by addition of iron +2 chelator but not by iron +3 chelator. These results suggest that an iron-MPTP complex promotes the formation of lipid peroxidation by interacting directly with membrane polyunsaturated lipids.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1985

[Post-therapeutic benzoyl peroxide contact allergy in ulcus cruris patients].

Of 739 dermatitis patients, 4.1% showed a positive patch test reaction to benzoyl peroxide 1% in petrolatum. Forty-one patients with leg ulcers (patch test: negative to benzoyl peroxide) were treated with a 20% benzoyl peroxide emulsion for 4 weeks. After this therapy, the sensitization rate was as high as that for the maximization test, namely 76%. In most patients, the post-therapeutic allergy to benzoyl peroxide was accompanied by contact allergies to other therapeutic agents applied. Only 9 of 31 sensitized patients showed a monovalent benzoyl peroxide allergy. From the allergologic point of view, benzoyl peroxide cannot be recommended for the treatment of leg ulcers. However, there appears to be no danger in the treatment of acne vulgaris.

Administration, Topical↗
PubMed1984

[Penetration of benzoyl peroxide in the skin].

Benzoyl peroxide preparations have proven to be effective agents in the treatment of acne. In comparison to the numerous clinical communications, very few reports exist concerning the pharmacokinetics of benzoyl peroxide. The benzoyl peroxide content of abraded horny layers and its metabolite benzoic acid were investigated by high-pressure liquid chromatography after application (1-2 min) of emulsion containing benzoyl peroxide. It was found that benzoyl peroxide penetrates the stratum corneum very quickly where it is rapidly degraded to benzoic acid. No benzoyl peroxide depot in the stratum corneum could be demonstrated.

Adolescent↗
PubMed1996

Protective role of anion channel blocker in lipid peroxidation caused by H2O2 in microsomes of bovine pulmonary arterial smooth muscle tissue.

The role of hydroxyl radical (OH.) in H2O2-mediated stimulation of lipid peroxidation in microsomes of bovine pulmonary arterial smooth muscle tissue and the protective effects of DIDS, the anion channel blocker have been studied. Treatment of microsomes with H2O2 (1 mM) stimulate iron release, OH. production and lipid peroxidation. Pretreatment with DFO (an iron chelator) or DMTU (a hydroxyl radical scavenger) prevents OH. production and thereby reduces lipid peroxidation without any appreciable reduction of iron release. Simultaneous treatment of either DFO or DMTU with H2O2 significantly reduces lipid peroxidation and prevents OH. production without any significant reduction of iron release. However, addition of DFO or DMTU 2 min after treatment of the microsome with H2O2 does not produce any significant reduction of lipid peroxidation, OH production and iron release. Pretreatment of microsomes with DIDS markedly reduces the stimulation of lipid peroxidation without appreciably altering the increase in OH. production and iron release caused by H2O2.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1998

Radical-induced lipoprotein and plasma lipid oxidation in normal and apolipoprotein E gene knockout (apoE-/-) mice: apoE-/- mouse as a model for testing the role of tocopherol-mediated peroxidation in atherogenesis.

Exposure of plasma from apolipoprotein E gene knockout (apoE-/-) and control (CBA or C57BL/6J) mice plasma to a constant rate of aqueous peroxyl radicals (ROO.) resulted in the depletion of ascorbate, urate and alpha-tocopherol (alpha-TOH), with substantial and little lipid peroxidation, respectively. Alpha-TOH levels were 3-times higher in plasma from apoE-/- than control mice and its addition enhanced the oxidizability of control mouse plasma. In apoE-/- mouse plasma, alpha-TOH was associated primarily with very low density lipoprotein (VLDL), whereas in plasma from control mice, the vitamin was located largely in high density lipoproteins. Oxidation of isolated lipoproteins by ROO. resulted in the accumulation of lipid hydroperoxides to an extent that reflected the plasma concentration and alpha-TOH content of the different lipoprotein fractions. Oxidation of 'plasma' reconstituted from components of apoE-/- mice and/or human plasma showed that human and apoE-/- mouse lipoproteins peroxidized with similar kinetics, although the initiation of lipid peroxidation was greater in the presence of mouse than human lipoprotein-deficient plasma. Also, the chain length of lipid peroxidation in apoE-/- mouse plasma after ascorbate depletion appeared to be independent of the rate of ROO. generation. Together, these results show that the ROO. induced peroxidation of plasma lipoproteins in atherogenesis-susceptible apoE-/- mice exhibits some, though not all, features of tocopherol-mediated peroxidation (TMP). Therefore, apoE-/- mice may represent a suitable animal model to test a role for TMP in atherogenesis and the prevention of this disease by anti-TMP agents.

Animals↗
PubMed1989

Hydrogen peroxide damage to human corneal epithelial cells in vitro. Implications for contact lens disinfection systems.

We investigated the cytotoxicity of hydrogen peroxide by exposing primary cell cultures of human corneal epithelium to a single dose of this agent at concentrations ranging from 30 to 100 ppm. Hydrogen peroxide, at a concentration as low as 30 ppm, caused cell retraction as well as cessation of cell movement and mitotic activity. Formation of membranous vesicles preceded cell death that occurred by 7 to 8 hours after exposure to 30 ppm. With a concentration of 50 ppm, normal cell activity ceased almost instantaneously. Numerous surface vesicles formed by 1.5 hours of exposure, and the cells died by 4 to 5 hours. Higher concentrations of hydrogen peroxide (70 to 100 ppm) caused cell death within a few minutes. Because neutralization of hydrogen peroxide and patient compliance are critical in the proper use of hydrogen peroxide-based contact lens disinfection systems, users will be well served if the long-term effects of residual peroxide on the cornea are subjected to continued study.

Cell Survival↗
PubMed1997

Free radical scavenging and antioxidative properties of 'silibin' complexes on microsomal lipid peroxidation.

The antioxidant properties of silibin complexes, the water-soluble form silibin dihemisuccinate (SDH), and the lipid-soluble form, silibin phosphatidylcholine complex known as IdB 1016, were evaluated by studying their abilities to react with the superoxide radical anion (O2-.), and the hydroxyl radical (OH.). In addition, their effect on pulmonary and hepatic microsomal lipid peroxidation had been investigated. Superoxide radicals were generated by the PMS-NADH system and measured by their ability to reduce NBT. IC50 concentrations for the inhibition of the NBT reduction by SDH and IdB 1016 were found to be 25 microM and 316 microM respectively. Both silibin complexes had an inhibitory effect on xanthine oxidase activity. SDH reacted rapidly with OH radicals at approximately diffusion controlled rate and the rate constant was found to be (K = 8.2 x 10(9) M-1 s-1); it appeared to chelate Fe2+ in solution. In hepatic microsomes, when lipid peroxidation was induced by Fe2+, SDH inhibited by 39.5 per cent and IdB 1016 by 19.5 per cent, whereas when lipid peroxidation was induced by CuOOH, IdB 1016 exerted a better protective effect than SDH (29.4 per cent and 19.4 per cent inhibition, respectively). In both microsomal systems lipid peroxidation proceeded through a thiol depletion mechanism which could be restored in the presence of silibin complexes. Low levels of lipid peroxidation in pulmonary microsomes point out the differences between in-vitro lipid peroxidation occurring in microsomes of different tissues. The results support the free radical scavenger and antioxidative properties of silibin when it is complexed with a suitable molecule to increase its bioavailability.

Animals↗
PubMed1992

Novel inhibitors of iron-dependent lipid peroxidation for neurodegenerative disorders.

A considerable body of information supports the occurrence and pathophysiological importance of oxygen radical-mediated lipid peroxidation in acute cerebral damage secondary to traumatic or ischemic injury. Moreover, peroxidative mechanisms have been implicated in chronic neurodegenerative (e.g., Alzheimer's and Parkinson's diseases) and demyelinating (e.g., multiple sclerosis) disorders. Consequently, there has been interest in identification of pharmacological agents with potent ability to interrupt oxygen radical formation or cell membrane lipid peroxidative mechanisms. Our laboratories have developed a novel series of potent lipid peroxidation inhibitors known as the 21-aminosteroids or "lazaroids." One of these compounds, U-74006F or tirilazad mesylate, has shown efficacy in animal models of brain injury and focal cerebral ischemia. In addition, the compound has been found to attenuate the increased lipid peroxidation observed in Alzheimer's brain tissue, to retard anterograde degeneration of motor nerve fibers, and to be effective in decreasing the clinical disease severity and blood-brain barrier disruption observed in the multiple sclerosis model of experimental allergic encephalomyelitis. Another series of antioxidants, the 2-methylaminochromans typified by the compound U-78517F, have been discovered that are even more potent and effective inhibitors of lipid peroxidation than the 21-aminosteroids.

Animals↗
PubMed2005

Borate-catalyzed reactions of hydrogen peroxide: kinetics and mechanism of the oxidation of organic sulfides by peroxoborates.

The kinetics of the oxidation of substituted phenyl methyl sulfides by hydrogen peroxide in borate/boric acid buffers were investigated as a function of pH, total peroxide concentration, and total boron concentration. Second-order rate constants at 25 degrees C for the reaction of methyl 4-nitrophenyl sulfide and H(2)O(2), monoperoxoborate, HOOB(OH)(3) (-), or diperoxoborate, (HOO)(2)B(OH)(2) (-), are 8.29 x 10(-5), 1.51 x 10(-2) and 1.06 x 10(-2) M(-1) s(-1), respectively. Peroxoboric acid, HOOB(OH)(2), is unreactive. The Hammett rho values for the reactions of a range of substituted phenyl methyl sulfides and hydrogen peroxide, monoperoxoborate or diperoxoborate are -1.50 +/- 0.1, -0.65 +/- 0.07 and -0.48 (two points only), respectively. The rho values for the peroxoborates are of significantly lower magnitude than expected from their reactivity compared to other peroxides. Nevertheless the negative rho values indicate positive charge development on the sulfur atom in the transition state consistent with nucleophilic attack by the organic sulfides on the peroxoborates as with the other peroxides. The kinetic parameters, including the lack of reactivity of peroxoboric acid, are discussed in terms of the differences in the transition state of reactions involving peroxoboron species with respect to those of other peroxides.

Borates↗
PubMed1990

Prevention of hepatocyte injury and lipid peroxidation by iron chelators and alpha-tocopherol in isolated iron-loaded rat hepatocytes.

These experiments were performed to characterize the relationship between lipid peroxidation and hepatocyte viability in iron overload. Hepatocytes were isolated from rats with chronic dietary iron overload and the effects of in vitro iron chelation on lipid peroxidation, cell viability and ultrastructure were studied over a 4-hr incubation period. Cell viability was significantly reduced at 3 and 4 hr in iron-loaded hepatocytes compared with controls and was preceded by an increase in iron-dependent lipid peroxidation. Similarly, extensive degenerative ultrastructural changes were observed in iron-loaded hepatocytes compared with controls after 4 hr of incubation. In vitro iron chelation with either deferoxamine or apotransferrin protected against lipid peroxidation, loss of viability and ultrastructural damage in iron-loaded hepatocytes. The addition of an antioxidant, alpha-tocopherol, also protected against lipid peroxidation and preserved cell viability over a 4-hr incubation. The protective effects of iron chelators and alpha-tocopherol support a strong association between iron-dependent lipid peroxidation and hepatocellular injury in iron overload.

Animals↗
PubMed1992

Role of cytochrome P-450 2E1 in ethanol-, carbon tetrachloride- and iron-dependent microsomal lipid peroxidation.

This study investigated the role of cytochrome P-450 2E1 in enhanced microsomal lipid peroxidation in experimental alcoholic liver disease. We also examined the contribution of this isoform to the increased microsomal injury in alcoholic liver disease caused by carbon tetrachloride-induced or iron-induced oxidant stress. Adult male Wistar rats were intragastrically infused with a high-fat diet and ethanol or glucose for 16 wk; this resulted in hepatic lipid peroxidation and fibrogenesis in the ethanol-fed animals. Microsomes were isolated by differential centrifugation in the presence of 100 mumol/L deferoxamine, washed twice in buffer without deferoxamine and incubated in the absence or presence of ethanol (50 mmol/L), carbon tetrachloride (150 mumol/L), ferric citrate (50 mumol/L) or ferric citrate plus ethanol at 37 degrees C for 30 min in an NADPH-generating system. The basal rate of lipid peroxidation in microsomes isolated from ethanol-fed rats was increased by 52% compared with that in microsomes from controls. Carbon tetrachloride-induced and ferric citrate-induced lipid peroxidation were also accentuated in microsomes from ethanol-fed rats, by 76% and 108%, respectively. Ethanol added in vitro significantly reduced basal (-58%) and ferric citrate-induced (-48%) lipid peroxidation in microsomes from ethanol-fed rats, whereas it had an insignificant effect on that in control microsomes. In fact, this protective effect of ethanol on microsomes from ethanol-fed rats resulted in attenuation of the difference in the level of microsomal lipid peroxidation between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

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.

Alanine Transaminase↗
PubMed1990

Effect of chronic halothane exposure on lipid peroxidation, osmotic fragility and morphology of rat erythrocytes.

Effect of chronic halothane exposure on hepatic and erythrocyte lipid peroxidation and erythrocyte osmotic fragility and morphology were determined in rats exposed to 0.4% halothane, 8 h per day for 40 days. Hepatic lipid peroxidation was increased in the halothane-treated group compared to controls. Lipid peroxidation was not increased by halothane exposure in erythrocytes without hydrogen peroxide, but after peroxide supplementation lipid peroxidation increased more in the erythrocytes of halothane-exposed rats than in control rats. We have observed significant morphological changes in erythrocytes from halothane-treated rats. In addition, erythrocytes of halothane-treated rats were more fragile in saline solutions compared to those of controls. Our results suggest that chronic halothane exposure is not only hepatotoxic but also affects erythrocyte membrane structure and stability.

Administration, Inhalation↗
PubMed1990

Hemoglobin degradation, lipid peroxidation, and inhibition of Na+/K(+)-ATPase in rat erythrocytes exposed to acrylonitrile.

The effect of acrylonitrile (VCN) on erythrocyte lipid metabolism was investigated in vitro in metabolically active red cells from male Sprague-Dawley rats containing three types of hemoglobins: oxyhemoglobin, methemoglobin, and carbon monoxyhemoglobin. VCN at the concentration of 10 mM rapidly depleted erythrocyte glutathione (GSH) (75% of control) and induced lipid peroxidation (274% of control). Degradation of oxy- and methemoglobin was directly proportional to the extent of lipid peroxidation (r = 0.89). Addition of glucose to the incubation medium decreased hemoglobin degradation while it slightly increased VCN-induced lipid peroxidation. The highest amount of lipid peroxidation occurred in erythrocytes containing carbon monoxyhemoglobin and glucose. In the isolated red cell membranes incubated with 10 mM VCN, the lipid peroxidation was 400% of controls. VCN (25 mM) noncompetitively inhibited erythrocyte membrane Na+/K(+)-ATPase activity and the degree of inhibition was inversely proportional to the reaction temperature (r = -0.88). These findings indicate that the VCN induced hemoglobin degradation and lipid peroxidation are two extremes of a spectrum of oxidative damage in red cells leading to a change in physical state of membrane structure causing inhibition of adenosine triphosphate (ATPase) activity.

Acrylonitrile↗
PubMed1995

Reduced glutathione esters--antidotes to toxicity. Cytotoxicity induced by hydrogen peroxide, 1-chloro-2,4-dinitrobenzene, and menadione in murine P388D1 macrophages in vitro.

Repletion of depleted cellular reduced glutathione (GSH) levels in oxidative stress and exposure to arylating agents is a strategy for the development of antidotes to chemical toxicity. The effect of GSH, reduced glutathione ethyl monoester (GSHEt), and reduced glutathione ethyl diester (GSHEt2) on the cytotoxicity of hydrogen peroxide, 1-chloro-2,4-dinitrobenzene (CDNB), and menadione to P388D1 macrophages in vitro was investigated. The median toxic concentration TC50 values of the toxicants were hydrogen peroxide 24 +/- 2 mM (N = 19), CDNB 63 +/- 6 microM (N = 18), and menadione 30 +/- 4 microM (N = 22). Reduced glutathione, GSHEt, and GSHEt2 were poor antidotes to hydrogen peroxide toxicity. Indeed, the observed antidote effects were attributed to the nonenzymatic reaction of the GSH derivatives with hydrogen peroxide in the extracellular medium. Reduced glutathione ethyl diester was a more potent antidote of CDNB- and menadione-mediated toxicity than GSHEt and GSH. For cell incubations with the approximate median toxic concentration TC50 values of hydrogen peroxide, CDNB, and menadione, the respective median effective antidote concentration EC50 values were GSHEt 23.8 +/- 4.1 mM (N = 9), 3.6 +/- 0.6 mM (N = 11), and 226 +/- 93 microM (N = 12); and GSHEt2 20.4 +/- 1.9 mM (N = 6), 603 +/- 2 microM (N = 9), and 7.6 +/- 2.3 microM (N = 12). Reduced glutathione ethyl diester was a potent antidote to CDNB- and menadione-induced toxicities but not to hydrogen peroxide-induced toxicity under acute intoxication conditions.

Animals↗
PubMed1988

Disturbance of cell proliferation by two model compounds of lipid peroxidation contradicts causative role in proliferative senescence.

Cumene hydroperoxide (Chp), a lipophilic peroxide, and hydroxy-nonenal (HNE), a breakdown product of lipid peroxides, were used as model compounds to assess the effects of lipid peroxidation upon cell proliferation. Amniotic fluid fibroblastlike (AFFL) cells and human diploid skin-derived (HDFL) cells were cultured with the two model compounds and cell proliferation was assayed via bromodeoxyuridine-Hoechst flow cytometry. At low doses Chp elicited an accumulation of cells in the S and G2 phase, while at higher doses the fraction of nonproliferating cells increased as well. Low doses of HNE caused an accumulation of cells in the G1 and G2 phase, whereas an additional increase of cells in S phase and in the nonproliferating fraction was found at an elevated concentration. A delay of onset of proliferation was obtained with both Chp and HNE. Permanent arrests in the S, G2, and G1 compartment are provoked by Chp only when Chp was applied together with serum. HNE, to the contrary, elicited a permanent arrest in the G2 and the G1 compartment even if added to quiescent cell cultures. Additionally, HNE caused a combination of a prolongation of the G1 phase of the cell cycle and an arrest in this compartment, which is reminiscent of cell differentiation. HDFL cells were much more sensitive toward Chp than were AFFL cells, but both cell types showed similar sensitivities toward HNE. We conclude that lipophilic peroxides exert toxic effects upon cell proliferation distinct from the pattern elicited by aldehydic breakdown products of lipid peroxides. The pattern of cell cycle arrest induced by Chp and HNE makes it unlikely that Chp and HNE, or related products of lipid peroxidation, are responsible for the limitation of the proliferative life span of human fibroblasts in culture.

Aldehydes↗
PubMed2005

Generation of hydrogen peroxide during brief oxygen-glucose deprivation induces preconditioning neuronal protection in primary cultured neurons.

Although reactive oxygen species (ROS) have been implicated in ischemic preconditioning (IPC)-induced neuronal protection, several key questions concerning ROS remain to be elucidated. The purpose of this study is to obtain direct evidence for the formation of specific ROS species generated by IPC, and to determine the specific species that is responsible for the observed neuronal protection. Primary cultured cortex neurons from rat embryos were preconditioned with 10 min of oxygen-glucose deprivation (OGD), which increased the intracellular levels of superoxide and hydrogen peroxide. This preconditioning markedly induced neuronal protection against 2-hr OGD stimuli. Preconditioning with exogenous ROS by the administration of xanthine/xanthine oxidase (X/XO), or hydrogen peroxide was also found to induce IPC-like neuronal protection. Administration of hydrogen peroxide scavengers, such as catalase, glutathione, or the thiol reductant N-(2-mercaptopriopionyl)-glycine, all reduced the increase in the intracellular hydrogen peroxide levels, which effectively eliminated IPC- or exogenous ROS-induced neuronal protection. In contrast, administration of the membrane-permeable superoxide dismutase mimic Mn(III)tetrakis(1-methyl-4-pyridyl)porphyrin pentachloride was able to block the increase of intracellular superoxide levels during IPC, but did not abolish either IPC- or exogenous X/XO preconditioning-induced neuronal protection. These findings strongly suggest that IPC enhances the generation of superoxide, which is then converted to hydrogen peroxide, and that hydrogen peroxide is likely the main trigger involved in the mechanism of IPC-induced neuronal protection.

Animals↗