H2O2-induced Lipid Peroxidation Research Articles

Novel Indole-Based Analogs of Melatonin: Synthesis and in Vitro Antioxidant Activity Studies

The aim of this study was to synthesize and examine possible in vitro antioxidant effects of indole-based melatonin analogue compounds. As a part of our ongoing study nineteen indole hydrazide/hydrazone derivatives were synthesized, characterized and their in vitro antioxidant activity was investigated by three different assays: by evaluating their reducing effect against oxidation of a redox sensitive fluorescent probe, by examining their protective effect against H2O2-induced membrane lipid peroxidation and by determining their inhibitory effect on AAPH–induced hemolysis of human erythrocytes. The results indicated significant strong antioxidant activity for most of the compounds, when compared to melatonin.

Evaluation of Azadirachta indica Leaf Fractions for in Vitro Antioxidant Potential and Protective Effects against H2O2-Induced Oxidative Damage to pBR322 DNA and Red Blood Cells

We evaluated the protective effects of subfractions of the ethyl acetate fraction (EAF) and the methanolic fraction (MF) from the crude ethanolic extract (CEE) of Azadirachta indica A. Juss (neem) leaves against various free radicals and hydrogen peroxide (H2O2)-induced oxidative damage to red blood cells (RBCs) and pBR322 DNA. Neem leaf fractions reduced DPPH(*), ABTS(*+), superoxide (O(*-)), hydroxyl (OH(*)), and nitric oxide radicals to nonradical forms in a concentration-dependent manner. Treatment with the benzene insoluble fraction from EAF (EBIF), the chloroform insoluble fraction from EAF (ECIF), the chloroform insoluble fraction from MF (MCIF), and the ethyl acetate insoluble fraction from MF (MEIF) significantly mitigated H2O2-induced oxidative damage to RBCs and pBR322 DNA. Although we found low in vitro free radical scavenging activity for the benzene insoluble fraction from EAF (EBSF), the chloroform soluble fraction from EAF (ECSF), the chloroform soluble fraction from MF (MCSF), and the ethyl acetate soluble fraction from MF (MESF), these fractions showed no effect on H2O2-induced lipid peroxidation and pBR322 DNA damage. High-performance liquid chromatography (HPLC) and TLC-Iatroscan analysis revealed that the greater efficacy of EBIF, ECIF, MCIF, and MEIF may be due to the presence of more polar compounds such as nimbolide and quercetin. Our studies suggest that the antioxidant and protective effects of active neem leaf fractions against H2O2-induced lipid peroxidation and pBR322 DNA damage can be attributed to their ability to inhibit various free radicals.

Date Seed Oil Inhibits Hydrogen Peroxide-Induced Oxidative Stress in Normal Human Epidermal Melanocytes

The administration of antioxidants has been shown to enhance repair and healing processes in cutaneous tissue. Date seed oil (DSO) extract, which might be a potential source of natural antioxidants such as phenols and tocopherols, has been reported to be beneficial in the reduction of chemically induced oxidative stress in normal human skin. In this study, we investigated the protective effects of DSO against hydrogen peroxide (H2O2)-induced oxidative stress in terms of lipid peroxidation, depletion of such endogenous antioxidant defense enzymes as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) using normal human epidermal melanocytes (NHEM). The results showed that DSO, endowed with a radical scavenging ability, decreased oxidative injury by inhibition of damage caused by H2O2. Treatment of NHEM with DSO inhibited H2O2-induced lipid peroxidation. In addition, the extract inhibited H2O2-induced depletion of antioxidant defense components, such as SOD, CAT, and GPx. Our findings demonstrate that DSO is an efficient extract able to prevent melanocytes oxidative damage induced by H2O2 exposure. Thus it may be a potential promising candidate, as a chemopreventive agent, in the development of melanocyte-related pathologies like vitiligo and melanoma.

Peroxide-induced cell death and lipid peroxidation in C6 glioma cells

Peroxides are often used as models to induce oxidative damage in cells in vitro. The aim of the present study was to elucidate the role of lipid peroxidation in peroxide-induced cell death. To this end (i) the ability to induce lipid peroxidation in C6 rat astroglioma cells of hydrogen peroxide (H2O2), cumene hydroperoxide (CHP) and t-butyl hydroperoxide (t-BuOOH) (ii) the relation between peroxide-induced lipid peroxidation and cell death in terms of time and concentration dependency and (iii) the capability of the lipid peroxidation chain breaking alpha-tocopherol to prevent peroxide-induced lipid peroxidation and/or cell death were investigated. Lipid peroxidation was characterised by measuring thiobarbituric acid reactive substances (TBARS) and, by HPLC, malondialdehyde (MDA), 4-hydroxynonenal (4-HNE) and hexanal. Within 2 h CHP, t-BuOOH and H2O2 induced cell death with EC50 values of 59+/-9 microM, 290+/-30 microM and 12+/-1.1 mM, respectively. CHP and t-BuOOH, but not H2O2 induced lipid peroxidation in C6 cells with EC50 values of 15+/-14 microM and 130+/-33 microM, respectively. The TBARS measured almost exclusively consisted of MDA. 4-HNE was mostly not detectable. The concentration of hexanal slightly increased with increasing concentrations of organic peroxides. Regarding time and concentration dependency lipid peroxidation preceded cell death. Pretreatment with alpha-tocopherol (10 microM, 24 h) prevented both, peroxide-induced lipid peroxidation and cell death. The results strongly indicate a major role of lipid peroxidation in the killing of C6 cells by organic peroxides but also that lipid peroxidation is not involved in H2O2 induced cell death.

Rhapontigenin from Rheum undulatum Protects Against Oxidative-Stress-Induced Cell Damage Through Antioxidant Activity

The antioxidant properties of rhapontigenin and rhaponticin isolated from Rheum undulatum were investigated. Rhapontigenin was found to scavenge intracellular reactive oxygen species (ROS), the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, and hydrogen peroxide (H2O2). The radical scavenging effect of rhapontigenin was more effective than rhaponticin. Rhapontigenin protected against H2O2-induced membrane lipid peroxidation and cellular DNA damage, which are the main targets of oxidative stress-induced cellular damage. The radical scavenging activity of rhapontigenin protected Chinese hamster lung fibroblast (V79-4) cells exposed to H2O2 by inhibiting apoptosis. Rhapontigenin inhibited cell damage induced by serum starvation and was also found to increase the activity of catalase and its protein expression. Further, rhapontigenin increased phosphorylation of extracellular signal-regulated kinase (ERK) and inhibited the activity of activator protein 1 (AP-1), a redox-sensitive transcription factor. In summary, these results suggest that rhapontigenin protects V79-4 cells against oxidative damage by enhancing the cellular antioxidant activity and modulating cellular signal pathways.

Screening of free radical scavenging capacity and antioxidant activities of Rosmarinus officinalis extracts with focus on location and harvesting times

Methanolic extracts from the leaves of Rosmarinus officinalis (rosemary) harvested from different locations of Turkey at four different times of the year were analyzed by HPLC, and their radical scavenging capacities and antioxidant activities were studied by various assays. The amounts of carnosol, carnosic acid and rosmarinic acid, active constituents of rosemary, varied in different geographical regions of growth, and also showed a seasonal variation. The levels of the constituents were higher in the warm months of June 2004 and September 2004. The antioxidant activities of 12 extracts were determined by in vitro DPPH radical scavenging activity, by Trolox equivalent antioxidant capacity (TEAC), and by reversing H2O2-induced erythrocyte membrane lipid peroxidation (EMLP). The two antioxidant enzyme activities of human erythrocyte, namely superoxide dismutase (SOD) and catalase (CAT), after in vitro incubation with the extracts, were also examined in order to see whether the observed effects are related to altered enzymatic efficiency. The resulting values were correlated with active metabolite and total phenol contents of the extracts. The results indicated that the plants harvested in September possessing higher levels of active constituent had superior antioxidant capacities compared to the ones collected at other times. With respect to the location, plants harvested from the Izmir region had lower total phenol and active constituent levels resulting in poorer antioxidant activity.

Antioxidant and Anti-inflammatory Activities of the Methanolic Extract of Neorhodomela aculeate in Hippocampal and Microglial Cells

The antioxidant and anti-inflammatory properties of the marine red alga Neorhodomela aculeate (N. aculeata) Masuda were investigated with neuronal and microglial cells. Extracts of N. aculeata had potent neuroprotective effects on glutamate-induced neurotoxicity and inhibited reactive oxygen species (ROS) generation in the murine hippocampal HT22 cell line. Also, extracts of N. aculeata inhibited H2O2-induced lipid peroxidation in rat brain homogenates. The properties of the extract as an anti-inflammatory agent were investigated in microglial activation by interferon-gamma (IFN-gamma): it reduced the inducible nitric oxide synthase that consequently resulted in the reduction of nitric oxide. These results suggest that the marine red alga N. aculeata could be considered as a potential source for reducing reactive oxygen species and inflammation related to neurological diseases.

Antioxidant and antiinflammatory activities of xanthorrhizol in hippocampal neurons and primary cultured microglia

Xanthorrhizol, a natural sesquiterpenoid isolated from the rhizome of Curcuma xanthorrhiza Roxb (Zingiberaceae), has antibacterial activities and protective effects against cisplatin-induced hepatotoxicity. In this study, we investigated the activities of xanthorrhizol as an antioxidant or antiinflammatory agent using neuronal and microglial cells. Xanthorrhizol had potent neuroprotective effects on glutamate-induced neurotoxicity and reactive oxygen species (ROS) generation in the murine hippocampal HT22 cell line. Also, xanthorrhizol inhibited H(2)O(2)-induced lipid peroxidation in rat brain homogenates. The properties of xanthorrhizol as an antiinflammatory agent were investigated in microglial activation by lipopolysaccharide. It reduced the expression of cyclooxygenase-2 and the inducible nitric oxide synthase, which consequently resulted in the reduction of nitric oxide. The production of proinflammatory cytokines, such as interleukin-6 and tumor necrosis factor-alpha in activated microglial cells, was reduced by xanthorrhizol. These results suggest that xanthorrhizol could be an effective candidate for the treatment of Alzheimer's disease- and other neurological disease-related ROS and inflammation.

Protective Effect of Propofol Against Kainic Acid-Induced Lipid Peroxidation in Mouse Brain Homogenates

This study compared the effectiveness of propofol with that of trolox and melatonin for reduction of lipid peroxidation in vitro. Lipid peroxidation was induced by addition of kainic acid (KA; 10 mM), hydrogen peroxide (H2O2; 10 mM), or ferrous ammonium sulfate (5 microM) to mouse brain homogenate, and thiobarbituric acid-reactive substances (TBA-RS) were used as a marker of lipid peroxidation. Propofol, trolox, and melatonin reduced KA-, H2O2-, and ferrous ammonium sulfate-induced lipid peroxidation in a concentration-dependent manner. In reducing KA-induced lipid peroxidation, 50% inhibitory concentration (IC50) values of antioxidants were as follows: propofol (11.33 mM), trolox (4.00 mM), and melatonin (9.72 mM). In reducing H2O2-induced lipid peroxidation, IC50 values of antioxidants were as follows: propofol (56.86 mM), trolox (33.34 mM), and melatonin (26.63 mM). In reducing ferrous ion-induced lipid peroxidation, IC50 values of antioxidants were as follows: propofol (49.57 mM), trolox (60.35 mM), and melatonin (22.02 mM). Under the in vitro conditions of this experiment, propofol was an excellent and a very potent antioxidant in inhibiting KA-, H2O2-, and ferrous ion-induced lipid peroxidation in mouse brain homogenates. We conclude that the antioxidant properties of propofol at clinically relevant anesthetic concentrations may have a neuroprotective effect.

Probucol as a potent inhibitor of oxygen radical-induced lipid peroxidation and DNA damage: in vitro studies

Probucol, a clinically used cholesterol lowering and antioxidant drug, was investigated for possible protection against lipid peroxidation and DNA damage induced by iron nitrilotriacetate (Fe-NTA) plus hydrogen peroxide (H2O2). Fe-NTA is a potent nephrotoxic agent and induces acute and subacute renal proximal tubular necrosis by catalyzing the decomposition of H2O2-derived production of hydroxyl radicals, which are known to cause lipid peroxidation and DNA damage. Fe-NTA is associated with a high incidence of renal adenocarcinoma in rodents. Lipid peroxidation and DNA damage are the principal manifestation of Fe-NTA induced toxicity, which could be mitigated by probucol. Incubation of renal microsomal membrane and/or calf thymus DNA with H2O2 (40 mM) in the presence of Fe-NTA (0.1 mM) induces renal microsomal lipid peroxidation and DNA damage to about 2.4-fold and 5.9-fold, respectively, as compared to control (P < 0.05). Induction of renal microsomal lipid peroxidation and DNA damage was inhibited by probucol in a concentration-dependent manner. In lipid peroxidation protection studies, probucol treatment showed a concentration-dependent inhibition (10–34% inhibition; P <0.05) of Fe-NTA plus H2O2-induced lipid peroxidation as measured by thiobarbituric acid reacting species' (TBARS) formation in renal microsomes. Similarly, in DNA damage protection studies, probucol treatment also showed a concentration-dependent strong inhibition (36–71% inhibition; P < 0.05) of DNA damage. From these studies, it was concluded that probucol inhibits peroxidation of microsomal membrane lipids and DNA damage induced by Fe-NTA plus H2O2. However, because the lipid peroxidation and DNA damage studied here are regarded as early markers of carcinogenesis, we suggest that probucol may be developed as a cancer chemopreventive agent against renal carcinogenesis and other adverse effects of Fe-NTA exposure in experimental animals, in addition to being a cholesterol-lowering drug, useful for the control of hypercholestrolemia.

Protective effect of green tea polyphenol (-)-epigallocatechin gallate and other antioxidants on lipid peroxidation in gerbil brain homogenates.

The aim of this study was to compare the protective effects of green tea polyphenol (-)-epigallocatechin gallate (EGCG) and other well-known antioxidants on the lipid peroxidation in gerbil brain homogenates. Oxidative stress was induced by H2O2 (10 mM) or ferrous ammonium sulfate (5 microM) and lipid peroxidation was studied. Hydrogen peroxide and ferrous ions are capable of oxidizing a wide range of substrates and causing biological damage. The reaction, referred to as the Fenton process, is complex and can generate both hydroxyl radicals and higher oxidation states of the iron. Thiobarbituric acid-reactive substances (TBA-RS) were used as a marker of lipid peroxidation. EGCG, trolox, lipoic acid, and melatonin reduced H2O2- or ferrous ion-induced lipid peroxidation in a concentration-dependent manner. In reducing the H2O2-induced lipid peroxidation, IC50 values of antioxidants were as follows: EGCG (0.66 microM), trolox (37.08 microM), lipoic acid (7.88 mM), and melatonin (19.11 mM). In reducing the ferrous ion-induced lipid peroxidation, IC50 values of antioxidants were as follows: EGCG (3.32 microM), trolox (75.65 microM), lipoic acid (7.63 mM), and melatonin (15.48 mM). Under the in vitro conditions of this experiment, EGCG was the most potent antioxidant in inhibiting H2O2 or ferrous ion-induced lipid peroxidation in the gerbil brain homogenates.

Effects of Added Dietary Taurine on Erythrocyte Lipids and Oxidative Stress in Rabbits Fed a High Cholesterol Diet

Lipid peroxidation leads to damage of polyunsaturated fatty acids of membrane phospholipids. The contribution of oxidative stress to hypercholesterolemia-induced hemolytic anemia and the effects of addition of taurine on erythrocyte lipid composition, oxidative stress, and hematological data were studied in rabbits fed on a high cholesterol (HC) diet (1%, w/w) for 2 months. The effects of taurine on erythrocyte hemolysis and H2O2-induced lipid peroxidation were investigated in normal rabbit erythrocytes in vitro. The HC diet resulted in increases in plasma lipids and lipid peroxide levels as well as increases in cholesterol levels and the cholesterol:phospholipid ratio in the erythrocytes. This diet caused a hemolytic anemia, but lipid peroxide levels remained unchanged in the erythrocytes of the rabbits. Taurine (2.5%, w/w) added to the food has an ameliorating effect on plasma lipids and lipid peroxide levels in rabbits fed on a HC diet. This treatment also caused decreases in elevated erythrocyte cholesterol levels and cholesterol:phospholipid ratio due to the HC diet, but it did not prevent the hemolytic anemia and did not change erythrocyte lipid peroxide levels. In addition, in an in vitro study, taurine did not protect erythrocytes against H2O2-induced hemolysis or lipid peroxidation. These results show that the HC diet causes hemolytic anemia without any changes in erythrocyte lipid peroxidation, and taurine treatment was not effective against hemolytic anemia caused by the HC diet.

Prevention of H2O2‐induced red blood cell lipid peroxidation and hemolysis by aqueous extracted turmeric

The protective effect of the aqueous extracted turmeric antioxidant protein on H2O2-induced red blood cell lipid peroxidation and hemolysis was investigated. Turmeric antioxidant protein inhibited lipid peroxidation and hemolysis by 70% and 80%, respectively, and was found to be more effective as an antioxidant than were -tocopherol and curcumin.

The activity of the pentose phosphate pathway is increased in response to oxidative stress in Alzheimer's disease.

In order to assess the integrity of antioxidant enzymes in Alzheimer's disease, the activities of glutathione peroxidase, glutathione reductase and two enzymes of the pentose phosphate pathway (glucose-6-phosphate dehydrogenase and 6-phosphonogluconate dehydrogenase) were determined in three regions of postmortem neocortex of controls and subjects with Alzheimer's disease. The activities of glutathione peroxidase and glutathione reductase were unaffected in Alzheimer's disease. By contrast, there was a selective increase in the activities of glucose-6-phosphate dehydrogenase and 6-phosphonogluconate dehydrogenase in the inferior temporal cortex of Alzheimer subjects. These changes negatively correlated with the Fe2+/ascorbate-induced lipid peroxidation which (in a previous study of the same subjects) was also found to be selectively elevated in the inferior temporal cortex. Increased activity of the pentose phosphate pathway probably occurs in response to increased prooxidant activity since both glucose-6-phosphate and 6-phosphonogluconate inhibited H2O2-induced lipid peroxidation in a concentration dependant fashion (IC50 = 504 +/- 105 microM and 88 +/- 12 microM, respectively). Together, these data suggest that not only is oxidative stress a feature of Alzheimer's disease, but also that it occurs because of increased prooxidant activity rather than a diminished antioxidant capacity.

Metallothionein-overexpressing neonatal mouse cardiomyocytes are resistant to H2O2 toxicity.

To study cellular and molecular events of cardiac protection by metallothionein (MT) from oxidative injury, a primary neonatal cardiomyocyte culture was established from a specific cardiac MT-overexpressing transgenic mouse model. Ventricular cardiomyocytes were isolated from 1- to 3-day-old neonatal mice and cultured in an Eagle's minimum essential medium supplemented with 20% fetal bovine serum under an atmosphere of 5% CO2-95% air at 37 degreesC. Forty-eight hours after plating was completed, the purity of such cultures was 95% myocytes, assessed by an immunocytochemical assay. Over 80% of the cardiomyocytes beat spontaneously on the first day of culture and synchronously in a confluent monolayer after the sixth day of culture. Cellular MT concentrations in the transgenic cardiomyocytes before culturing and on the sixth day postculturing were about seven- and twofold higher than nontransgenic controls, respectively. However, there were no significant differences in cell morphology, glutathione content, and antioxidant enzymatic activities between these two types of cardiomyocytes. When these cells were challenged by H2O2, the transgenic cardiomyocytes displayed a significant resistance to the toxic effect of this oxidant, as measured by cell viability, lactate dehydrogenase leakage, and morphological alterations. In addition, the transgenic cells were highly protected from H2O2-induced lipid peroxidation. These observations demonstrate that MT protects the cultured cardiomyocytes from H2O2 toxicity by preventing its interaction with macromolecules such as lipids, and this cultured primary neonatal mouse cardiomyocyte system provides a valuable tool to directly study cellular and molecular events of MT in cardiac protection against oxidative injury.

Two Mechanisms for Toxic Effects of Hydroxylamines in Human Erythrocytes: Involvement of Free Radicals and Risk of Potentiation

ABSTRACT: The toxic potency of three industrially used hydroxylamines was studied in human blood cellsin vitro. The parent compound hydroxylamine and the O-ethyl derivative gave very similar results. Both compounds induced a high degree of methemoglobin formation and glutathione depletion. Cytotoxicity was visible as Heinz body formation and hemolysis. High levels of lipid peroxidation occurred, in this respect O-ethyl hydroxylamine was more active than hydroxylamine. In contrast H2O2induced lipid peroxidation was lowered after O-ethyl hydroxylamine or hydroxylamine treatment, this is explained by the ferrohemoglobin dependence of H2O2induced radical species formation. Glutathione S-transferase (GST) and NADPH methemoglobin reductase (NADPH-HbR) activities were also impaired, probably as a result of the radical stress occurring. The riboflavin availability was decreased. Other enzyme activities glutathione reductase (GR), glucose 6-phosphate dehydrogenase (G6PDH), glucose phosphate isomerase and NADH methemoglobin reductase, were not or only slightly impaired by hydroxylamine or O-ethyl hydroxylamine treatment. A different scheme of reactivity was found for N,O-dimethyl hydroxylamine. This compound gave much less methemoglobin formation and no hemolysis or Heinz body formation at concentrations up to and including 7 mM. Lipid peroxidase induction was not detectable, but could be induced by subsequent H2O2treatment. GST and NADPH-HbR activities and riboflavin availability were not decreased. On the other hand GR and G6PDH activities were inhibited. These results combined with literature data indicate the existence of two different routes of hematotoxicity induced by hydroxylamines. Hydroxylamine as well as O-alkylated derivatives primarily induce methemoglobin, a process involving radical formation. The radical stress occurring is probably responsible for most other effects. N-alkylated species like N,O-dimethyl hydroxylamine primarily lead to inhibition of the protective enzymes G6PDH and GR. Since these enzymes play a key role in the protection of erythrocytes against oxidative stress a risk of potentiation during mixed exposure does exist.

Nitric oxide attenuates hydrogen peroxide-mediated injury to porcine pulmonary artery endothelial cells.

To examine the role of nitric oxide (.NO) in vascular endothelial cell injury, cultured porcine pulmonary artery endothelial cells (PAEC) were treated with H2O2 (100-500 microM) for 30 min in the presence or absence of the .NO donors (+/-)S-nitroso-N-acetylpenicillamine (SNAP) or diethylamine nitric oxide (DEANO). H2O2 caused dose-dependent PAEC cytotoxicity detected 2 h after H2O2 treatment as the release of lactate dehydrogenase. SNAP (100 microM) and DEANO (100 microM) attenuated H2O2-induced cytotoxicity if present during H2O2 treatment. In contrast, restricting treatment with .NO donors to periods before (30 min) or after (2 h) incubation with H2O2 did not prevent PAEC injury. Furthermore, the .NO synthase inhibitor NG-nitro-L-arginine methyl ester (1 mM) sensitized PAEC to H2O2-induced injury. SNAP also attenuated H2O2-induced PAEC lipid peroxidation even if restricted to periods before or after exposure to H2O2. Thus, although .NO effectively attenuated H2O2-mediated PAEC lipid peroxidation and cytotoxicity, these effects were clearly dissociated, suggesting that the antiperoxidative effects of .NO are not sufficient to account for its cytoprotective properties.

Studies on curcumin and curcuminoids: XXVI. Antioxidant effects of curcumin on the red blood cell membrane

Abstract A natural polyphenol curcumin (Cur) was tested for its antioxidant effects on human red blood cell (RBC) and their membranes. Cur, at concentrations of 4–100 μM protected RBC against H2O2-induced lysis and lipid peroxidation (LPO). Cur (100 μM) caused significant inhibition of the LPO in normal RBC ghosts supplemented with exogenous iron and in β-thalassemic (Th) ghosts containing endogenous iron deposits. The Cur protective effect on Th ghosts was much more pronounced when ascorbic acid was added in the system (prior to H2O2) aiming to induce partial iron reduction. Cur alone did not change the ratio of Fe2+ /Fe3+ in these ghosts but significantly inhibited the rate of Fe2+ reoxidation by H2O2. The results indicate the possibility of Fe2+ complexing with Cur leading to a lower iron reactivity towards H2O2. Therefore Cur as a membrane antioxidant may protect Th RBC against iron-catalyzed oxidative damage.

Heart and red blood cell antioxidant status and plasma lipid levels in the spontaneously hypertensive and normotensive Wistar–Kyoto rat

Heart and red blood cell endogenous antioxidant status and plasma lipids were investigated in hypertensive, 14-week-old spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats fed a standard commercial rat chow. Specific heart and red blood cell antioxidant enzyme activities, as well as the susceptibility of tissues to H2O2-induced glutathione (GSH) depletion and lipid peroxidation, were measured. Systolic blood pressure in SHR was greater than in WKY rats at 13 weeks of age (197 +/- 12 vs. 132 +/- 14 mmHg (1 mmHg = 133.3 Pa); p < or = 0.05), confirming the presence of hypertension in SHR. Red blood cell catalase (CAT) and superoxide dismutase (SOD) activities were greater (p < or = 0.05) in SHR than WKY rats. Red blood cell CAT activity was positively correlated (r = +0.634; p = 0.026) with SOD, which in turn was correlated (r = +0.709; p = 0.049) with systolic blood pressure. Heart SOD activity was higher (p < or = 0.05) in SHR, while glutathione reductase (GSSG-Red) activity was lower (p < or = 0.05) than in WKY rats. This reduced ability to recycle GSH in the heart coincided with greater (p < or = 0.05) levels of H2O2-induced lipid oxidation products in SHR. Plasma total cholesterol and triacylglycerol levels were lower (p < or = 0.05) in SHR than WKY rats, with no visible signs of atherosclerosis in either SHR or WKY rats. In summary, hypertension in SHR was associated with alterations in antioxidant enzyme profiles of red blood cells and heart, with the latter showing an increased susceptibility to in vitro lipid oxidation. Although hypertension is a recognized factor in the development of human atherosclerosis, spontaneously hypertensive rats did not exhibit signs of aortic plaque, reflecting the resistance of this species to the development of atherosclerosis.

Inhibition of NF-κB Activation in Human T-Cell Lines by Anetholdithiolthione

Nuclear factor (NF)-κB is a redox sensitive cytosolic transcription factor. Redox regulation of NF-κB has been implicated in the activation of the human immuno-deficiency virus (HIV). Therefore, inhibition of NF-κB activation may be an effective strategy for acquired immunodeficiency syndrome therapy. Anetholdithiolthione (ADT, 5-[p-methoxyphenyl]-3H-1,2-dithiol-3-thione) is an antioxidant which has been used to protect against acetaminophen- and CCl4-induced hepatotoxicity, lipid peroxidation, radiation injury, and also has been used clinically as an anti-choleretic agent. The present study examined the effect of ADT pretreatment on NF-κB activation in response to a variety of stimuli such as H2O2, phorbol myrisitate acetate (PMA) or tumor necrosis factor α (TNFα). PMA and TNFα induced activation of (NF)-κB in human Jurkat T-cells was partially inhibited by ADT (0.1 mM) pretreatment. ADT (0.1 mM) also inhibited H2O2induced activation of the transcription factor in the peroxide sensitive human Wurzburg T-cells. Furthermore, ADT treated Wurzburg cells had significantly higher glutathione levels as compared with untreated cells. H2O2induced lipid peroxidation in Wurzburg cells was remarkably inhibited by ADT pretreatment. ADT, a pro-glutathione antioxidant, was observed to be capable of modulating NF-κB activation.