The water-soluble vitamin E analogue Trolox protects against ischaemia/reperfusion damage in vitro and ex vivo. A comparison with vitamin E

Fast FRAP-SIA method to determine antioxidant capacity

One of the most used methods to measure antioxidant capacity in food is the ferric reducing antioxidant power (FRAP) test, which is simple, sensitive, and economical, nevertheless has long analysis times, causing measurement errors due to the instability of the FRAP reagent due to its precipitation sequential injection analysis (SIA) is a flow technique that can correct these disadvantages because it is more quickly. So, a novel FRAP-SIA method was developed to evaluate the antioxidant capacity. The system was optimized using a central composite design for hydrodynamic and chemical factors, resulting in a flow rate of 35 μL s-1, and aspirate volumes of 33 μL-38 μL-33 μL for the sequence (FRAP-Antioxidant-FRAP). FRAP reagent was prepared with an HCl solution at 0.005 mol L-1, improving its stability 24 times, concerning when it is in acetate buffer at pH 3.6. The method showed excellent accuracy (RSD <3%) with a LOD of 1.0 μmol L-1 of Trolox for a linear range of 5-120 μmol L-1. The reaction time was diminished by 96% concerning the FRAP-microplate assay (from 30 min to 1.2 min). The method was applied in beverages and extracts, obtaining recovery values ranging from 91.24 to 114.22%.

Innovative approaches to Alzheimer's therapy: Harnessing the power of heterocycles, oxidative stress management, and nanomaterial drug delivery system

Alzheimer's disease (AD) presents a complex pathology involving amyloidogenic proteolysis, neuroinflammation, mitochondrial dysfunction, and cholinergic deficits. Oxidative stress exacerbates AD progression through pathways like macromolecular peroxidation, mitochondrial dysfunction, and metal ion redox potential alteration linked to amyloid-beta (Aβ). Despite limited approved medications, heterocyclic compounds have emerged as promising candidates in AD drug discovery. This review highlights recent advancements in synthetic heterocyclic compounds targeting oxidative stress, mitochondrial dysfunction, and neuroinflammation in AD. Additionally, it explores the potential of nanomaterial-based drug delivery systems to overcome challenges in AD treatment. Nanoparticles with heterocyclic scaffolds, like polysorbate 80-coated PLGA and Resveratrol-loaded nano-selenium, show improved brain transport and efficacy. Micellar CAPE and Melatonin-loaded nano-capsules exhibit enhanced antioxidant properties, while a tetra hydroacridine derivative (CHDA) combined with nano-radiogold particles demonstrates promising acetylcholinesterase inhibition without toxicity. This comprehensive review underscores the potential of nanotechnology-driven drug delivery for optimizing the therapeutic outcomes of novel synthetic heterocyclic compounds in AD management. Furthermore, the inclusion of various promising heterocyclic compounds with detailed ADMET (Absorption, Distribution, Metabolism, Excretion, and Toxicity) data provides valuable insights for planning the development of novel drug delivery treatments for AD.

Systems-level analyses dissociate genetic regulators of reactive oxygen species and energy production

Respiratory chain dysfunction can decrease ATP and increase reactive oxygen species (ROS) levels. Despite the importance of these metabolic parameters to a wide range of cellular functions and disease, we lack an integrated understanding of how they are differentially regulated. To address this question, we adapted a CRISPRi- and FACS-based platform to compare the effects of respiratory gene knockdown on ROS to their effects on ATP. Focusing on genes whose knockdown is known to decrease mitochondria-derived ATP, we showed that knockdown of genes in specific respiratory chain complexes (I, III, and CoQ10 biosynthesis) increased ROS, whereas knockdown of other low ATP hits either had no impact (mitochondrial ribosomal proteins) or actually decreased ROS (complex IV). Moreover, although shifting metabolic conditions profoundly altered mitochondria-derived ATP levels, it had little impact on mitochondrial or cytosolic ROS. In addition, knockdown of a subset of complex I subunits-including NDUFA8, NDUFB4, and NDUFS8-decreased complex I activity, mitochondria-derived ATP, and supercomplex level, but knockdown of these genes had differential effects on ROS. Conversely, we found an essential role for ether lipids in the dynamic regulation of mitochondrial ROS levels independent of ATP. Thus, our results identify specific metabolic regulators of cellular ATP and ROS balance that may help dissect the roles of these processes in disease and identify therapeutic strategies to independently target energy failure and oxidative stress.

Systems-level analyses dissociate genetic regulators of reactive oxygen species and energy production

Respiratory chain dysfunction can decrease ATP and increase reactive oxygen species (ROS) levels. Despite the importance of these metabolic parameters to a wide range of cellular functions and disease, we lack an integrated understanding of how they are differentially regulated. To address this question, we adapted a CRISPRi- and FACS- based platform to compare the effects of respiratory gene knockdown on ROS to their effects on ATP. Focusing on genes whose knockdown is known to decrease mitochondria-derived ATP, we showed that knockdown of genes in specific respiratory chain complexes (I, III and CoQ10 biosynthesis) increased ROS, whereas knockdown of other low ATP hits either had no impact (mitochondrial ribosomal proteins) or actually decreased ROS (complex IV). Moreover, although shifting metabolic conditions profoundly altered mitochondria-derived ATP levels, it had little impact on mitochondrial or cytosolic ROS. In addition, knockdown of a subset of complex I subunits-including NDUFA8, NDUFB4, and NDUFS8-decreased complex I activity, mitochondria-derived ATP and supercomplex level, but knockdown of these genes had differential effects on ROS. Conversely, we found an essential role for ether lipids in the dynamic regulation of mitochondrial ROS levels independent of ATP. Thus, our results identify specific metabolic regulators of cellular ATP and ROS balance that may help dissect the roles of these processes in disease and identify therapeutic strategies to independently target energy failure and oxidative stress.

Surface Lin28A expression consistent with cellular stress parallels indicators of senescence

AIMS

Declining cellular functional capacity resulting from stress or ageing is a primary contributor to impairment of myocardial performance. Molecular pathway regulation of biological processes in cardiac interstitial cells (CICs) is pivotal in stress and ageing responses. Altered localization of the RNA-binding protein Lin28A has been reported in response to environmental stress, but the role of Lin28A in response to stress in CICs has not been explored. Surface Lin28A redistribution is indicative of stress response in CIC associated with ageing and senescence.

METHODS AND RESULTS

Localization of Lin28A was assessed by multiple experimental analyses and treatment conditions and correlated to oxidative stress, senescence, and ploidy in adult murine CICs. Surface Lin28A expression is present on 5% of fresh CICs and maintained through Passage 2, increasing to 21% in hyperoxic conditions but lowered to 14% in physiologic normoxia. Surface Lin28A is coincident with elevated senescence marker p16 and beta-galactosidase (β-gal) expression in CICs expanded in hyperoxia, and also increases with polyploidization and binucleation of CICs regardless of oxygen culture. Transcriptional profiling of CICs using single-cell RNA-Seq reveals up-regulation of pathways associated with oxidative stress in CICs exhibiting surface Lin28A. Induction of surface Lin28A by oxidative stress is blunted by treatment of cells with the antioxidant Trolox in a dose-dependent manner, with 300 μM Trolox exposure maintaining characteristics of freshly isolated CICs possessing low expression of surface Lin28A and β-gal with predominantly diploid content.

CONCLUSION

Surface Lin28A is a marker of environmental oxidative stress in CICs and antioxidant treatment antagonizes this phenotype. The biological significance of Lin28 surface expression and consequences for myocardial responses may provide important insights regarding mitigation of cardiac stress and ageing.

Inflammation and Oxidative Stress in the Context of Extracorporeal Cardiac and Pulmonary Support

Extracorporeal circulation (ECC) systems, including cardiopulmonary bypass, and extracorporeal membrane oxygenation have been an irreplaceable part of the cardiothoracic surgeries, and treatment of critically ill patients with respiratory and/or cardiac failure for more than half a century. During the recent decades, the concept of extracorporeal circulation has been extended to isolated machine perfusion of the donor organ including thoracic organs (ex-situ organ perfusion, ESOP) as a method for dynamic, semi-physiologic preservation, and potential improvement of the donor organs. The extracorporeal life support systems (ECLS) have been lifesaving and facilitating complex cardiothoracic surgeries, and the ESOP technology has the potential to increase the number of the transplantable donor organs, and to improve the outcomes of transplantation. However, these artificial circulation systems in general have been associated with activation of the inflammatory and oxidative stress responses in patients and/or in the exposed tissues and organs. The activation of these responses can negatively affect patient outcomes in ECLS, and may as well jeopardize the reliability of the organ viability assessment, and the outcomes of thoracic organ preservation and transplantation in ESOP. Both ECLS and ESOP consist of artificial circuit materials and components, which play a key role in the induction of these responses. However, while ECLS can lead to systemic inflammatory and oxidative stress responses negatively affecting various organs/systems of the body, in ESOP, the absence of the organs that play an important role in oxidant scavenging/antioxidative replenishment of the body, such as liver, may make the perfused organ more susceptible to inflammation and oxidative stress during extracorporeal circulation. In the present manuscript, we will review the activation of the inflammatory and oxidative stress responses during ECLP and ESOP, mechanisms involved, clinical implications, and the interventions for attenuating these responses in ECC.

Protective effects of antioxidants on striatal dopamine release induced by organophosphorus pesticides

Although the toxic effects of organophosphorus (OP) pesticides have been classically attributed to inhibition of the acetylcholinesterase, other neurotoxic mechanisms, as oxidative stress can also occur. Here we evaluated if antioxidants prevent the excessive dopamine release induced by OP pesticides in conscious and freely moving rats, using cerebral microdialysis technique. Intrastriatal infusion of paraoxon (5 mM), glufosinate (10 mM) or glyphosate (5 mM) significantly increased the dopamine release (1006 ± 106%, 991 ± 142%, and 1164 ± 128%, relative to baseline, respectively). To evaluate if these increased dopamine release could be related to oxidative stress, we pretreated animals with antioxidants glutathione (GSH, 400 or 800 μM), dithiothreitol (DTT, 5 or 10 μM), trolox (1 or 3 mM), and α-lipoic acid (ALA, 400 or 800 μM) before administration of OP pesticides. Intrastriatal administration of the antioxidants GSH, DTT, trolox, and ALA was highly effective in preventing the glyphosate and glufosinate-induced dopamine overflow. However, only GSH (800 μM) significantly decreased the effect of paraoxon on dopamine levels. The high toxicity of this pesticide and the low concentrations used could explain this lack of effect in our experimental conditions. The fact that ROS scavengers prevent the excessive dopamine release induced by OP pesticides, further supports the view that dopamine overflow can cause neuronal damage mediated, at least in part, by oxidative stress.

Thiamine deficiency and recovery: impact of recurrent episodes and beneficial effect of treatment with Trolox and dimethyl sulfoxide

At present, thiamine deficiency (TD) is managed with administration of high doses of thiamine. Even so, severe and permanent neurological disorders can occur in recurrent episodes of TD. In this study, we used a murine model to assess the efficacy of TD recovery treatments using thiamine with or without additional administration of the antioxidant Trolox or the anti-inflammatory dimethyl sulfoxide (DMSO) after a single or recurrent episode of TD. TD was induced for 9 days with deficient chow and pyrithiamine, and the recovery period was 7 days with standard amounts of chow and thiamine, Trolox, and/or DMSO. After these periods, we evaluated behavior, histopathology, and ERK1/2 modulation in the brain. Deficient animals showed reductions in locomotor activity, motor coordination, and spatial memory. Morphologically, after a single episode of TD and recovery, deficient mice showed neuronal vacuolization in the dorsal thalamus and, after two episodes, a reduction in neuronal cell number. These effects were attenuated or reversed by the recovery treatments, mainly in the treatments with thiamine associated with Trolox or DMSO. Deficient animals showed a strong increase in ERK1/2 phosphorylation in the thalamus, hippocampus, and cerebral cortex after one deficiency episode and recovery. Interestingly, after recurrent TD and recovery, ERK1/2 phosphorylation remained high only in the deficient mice treated with thiamine and/or Trolox or thiamine with DMSO. Our data suggest that a protocol for TD treatment with thiamine in conjunction with Trolox or DMSO enhances the recovery of animals and possibly minimizes the late neurological sequelae.

Momordica charantia L. Extract Protects Hippocampal Neuronal Cells against PAHs-Induced Neurotoxicity: Possible Active Constituents Include Stigmasterol and Vitamin E

Polycyclic aromatic hydrocarbons (PAHs) have been recognized to cause neurobehavioral dysfunctions and disorder of cognition and behavioral patterns in childhood. Momordica charantia L. (MC) has been widely known for its nutraceutical and health-promoting properties. To date, the effect of MC for the prevention and handling of PAHs-induced neurotoxicity has not been reported. In the current study, the neuroprotective effects of MC and its underlying mechanisms were investigated in mouse hippocampal neuronal cell line (HT22); moreover, in silico analysis was performed with the phytochemicals MC to decipher their potential function as neuroprotectants. MC was demonstrated to possess neuroprotective effect by reducing reactive oxygen species’ (ROS’) production and down-regulating cyclin D1, p53, and p38 mitogen-activated protein kinase (MAPK) protein expressions, resulting in the inhibition of cell apoptosis and the normalization of cell cycle progression. Additionally, 28 phytochemicals of MC and their competence on inhibiting cytochrome P450 (CYP: CYP1A1, CYP1A2, and CYP1B1) functions were resolved. In silico analysis of vitamin E and stigmasterol revealed that their binding to either CYP1A1 or CYP1A2 was more efficient than the binding of each positive control (alizarin or purpurin). Together, MC is potentially an interesting neuroprotectant including vitamin E and stigmasterol as probable active components for the prevention for PAHs-induced neurotoxicity.

Self-assembled mono- and bilayers on gold electrodes to assess antioxidants—a comparative study

Oxidative stress is considered as an imbalance of reactive species over antioxidants, leading to diseases and cell death. Various methods have been developed to determine the antioxidant potential of natural or synthetic compounds based on the ability to scavenge free radicals. However, most of them lack biological relevance. Here, a gold-based self-assembled monolayer (SAM) was compared with a gold-supported lipid bilayer as models for the mammalian cell membrane to evaluate the free radical scavenging activity of different antioxidants. The oxidative damage induced by reactive species was verified by cyclic and differential pulse voltammetry and measured by the increase of electrochemical peak current of a redox probe. Trolox, caffeic acid (CA), epigallocatechin gallate (EGCG), ascorbic acid (AA), and ferulic acid (FA) were used as model antioxidants. The change in the decrease of the electrochemical signal reflecting oxidative membrane damage confirms the expected protective role. Both model systems showed similar efficacies of each antioxidant, the achieved order of radical scavenging potential is as follows: Trolox > CA > EGCG > AA > FA. The results showed that the electrochemical assay with SAM-modified electrodes is a stable and powerful tool to estimate qualitatively the antioxidative activity of a compound with respect to cell membrane protection against biologically relevant reactive species.

The effect of vitamin E supplementation on selected inflammatory biomarkers in adults: a systematic review and meta-analysis of randomized clinical trials

The previous meta-analysis of clinical trials revealed a beneficial effect of vitamin E supplementation on serum C-reactive protein (CRP) concentrations; however, it is unknown whether this vitamin has the same influence on other inflammatory biomarkers. Also, several clinical trials have been published since the release of earlier meta-analysis. Therefore, we aimed to conduct a comprehensive meta-analysis to summarize current evidence on the effects of vitamin E supplementation on inflammatory biomarkers in adults. We searched the online databases using relevant keywords up to November 2019. Randomized clinical trials (RCTs) investigating the effect of vitamin E, compared with the placebo, on serum concentrations of inflammatory cytokines were included. Overall, we included 33 trials with a total sample size of 2102 individuals, aged from 20 to 70 years. Based on 36 effect sizes from 26 RCTs on serum concentrations of CRP, we found a significant reduction following supplementation with vitamin E (− 0.52, 95% CI − 0.80, − 0.23 mg/L, P < 0.001). Although the overall effect of vitamin E supplementation on serum concentrations of interleukin-6 (IL-6) was not significant, a significant reduction in this cytokine was seen in studies that used α-tocopherol and those trials that included patients with disorders related to insulin resistance. Moreover, we found a significant reducing effect of vitamin E supplementation on tumor necrosis factor-α (TNF-α) concentrations at high dosages of vitamin E; such that based on dose–response analysis, serum TNF-α concentrations were reduced significantly at the dosages of ≥ 700 mg/day vitamin E (P_{non-linearity} = 0.001). Considering different chemical forms of vitamin E, α-tocopherol, unlike other forms, had a reducing effect on serum levels of CRP and IL-6. In conclusion, our findings revealed a beneficial effect of vitamin E supplementation, particularly in the form of α-tocopherol, on subclinical inflammation in adults. Future high-quality RCTs should be conducted to translate this anti-inflammatory effect of vitamin E to the clinical setting.

Thiamine Deficiency Modulates p38MAPK and Heme Oxygenase-1 in Mouse Brain: Association with Early Tissue and Behavioral Changes

Thiamine deficiency (TD) produces severe neurodegenerative lesions. Studies have suggested that primary neurodegenerative events are associated with both oxidative stress and inflammation. Very little is known about the downstream effects on intracellular signaling pathways involved in neuronal death. The primary aim of this work was to evaluate the modulation of p38^MAPK and the expression of heme oxygenase 1 (HO-1) in the central nervous system (CNS). Behavioral, metabolic, and morphological parameters were assessed. Mice were separated into six groups: control (Cont), TD with pyrithiamine (Ptd), TD with pyrithiamine and Trolox (Ptd + Tr), TD with pyrithiamine and dimethyl sulfoxide (Ptd + Dmso), Trolox (Tr) and DMSO (Dmso) control groups and treated for 9 days. Control groups received standard feed (AIN-93M), while TD groups received thiamine deficient feed (AIN-93DT). All the groups were subjected to behavioral tests, and CNS samples were collected for cell viability, histopathology and western blot analyses. The Ptd group showed a reduction in weight gain and feed intake, as well as a reduction in locomotor, grooming, and motor coordination activities. Also, Ptd group showed a robust increase in p38^MAPK phosphorylation and mild HO-1 expression in the cerebral cortex and thalamus. The Ptd group showed a decreased cell viability, hemorrhage, spongiosis, and astrocytic swelling in the thalamus. Groups treated with Trolox and DMSO displayed diminished p38^MAPK phosphorylation in both the structures, as well as attenuated thalamic lesions and behavioral activities. These data suggest that p38^MAPK and HO-1 are involved in the TD-induced neurodegeneration in vivo, possibly modulated by oxidative stress and neuroinflammation.

Nitrone-Trolox conjugate as an inhibitor of lipid oxidation: Towards synergistic antioxidant effects

Free radical scavengers like α-phenyl-N-tert-butylnitrone (PBN) and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) have been widely used as protective agents in various biomimetic and biological models. A series of three amphiphilic Trolox and PBN derivatives have been designed by adding to those molecules a perfluorinated chain as well as a sugar group in order to render them amphiphilic. In this work, we have studied the interactions between these derivatives and lipid membranes to understand how they influence their ability to prevent membrane lipid oxidation. We showed the derivatives better inhibited the AAPH-induced oxidation of 1,2-dilinoleoyl-sn-glycero-3-phosphocholine (DLiPC) small unilamellar vesicles (SUVs) than the parent compounds. One of the derivatives, bearing both PBN and Trolox moieties on the same fluorinated carrier, exhibited a synergistic antioxidant effect by delaying the oxidation process. We next investigated the ability of the derivatives to interact with DLiPC membranes in order to better understand the differences observed regarding the antioxidant properties. Surface tension and fluorescence spectroscopy experiments revealed the derivatives exhibited the ability to form monolayers at the air/water interface and spontaneously penetrated lipid membranes, underlying pronounced hydrophobic properties in comparison to the parent compounds. We observed a correlation between the hydrophobic properties, the depth of penetration and the antioxidant properties and showed that the location of these derivatives in the membrane is a key parameter to rationalize their antioxidant efficiency. Molecular dynamics (MD) simulations supported the understanding of the mechanism of action, highlighting various key physical-chemical descriptors.

Radicicol rescues yeast cell death triggered by expression of human α-synuclein and its A53T mutant, but not by human βA4 peptide and proapoptotic protein bax

Aggregation/misfolding of α-synuclein and βA4 proteins cause neuronal cell death (NCD) associated with Parkinson's and Alzheimer's disease. It has been suggested that a heat shock protein-90 (Hsp90) inhibitor can prevent NCD by activating the heat shock transcription factor-1 which, in turn, upregulates molecular chaperones such as Hsp70 that targets aggregated/misfolded proteins for refolding/degradation. We have isolated radicicol, an Hsp90 inhibitor, from a fungus occurring in the crevices of marble rocks of Central India. Radicicol, which was found to be a strong antioxidant, was tested for its ability to rescue yeast cells from death induced by expression of wild-type α-synuclein, its more toxic A53T mutant, and βA4. It effectively overcomes wild-type/mutant α-synuclein mediated yeast cell death, concomitantly diminishes ROS levels, reverses mitochondrial dysfunction and prevents nuclear DNA-fragmentation, a hallmark of apoptosis. Surprisingly however, radicicol is unable to rescue yeast cells from death triggered by expression of secreted βA4. Moreover, although radicicol acts as an antioxidant it fails to prevent yeast cell death inflicted by the proapoptotic protein, Bax. Our results indicate that radicicol specifically targets aggregated/misfolded α-synuclein's toxicity and opens up the possibility of using multiple yeast assays to screen natural product libraries for compounds that would unambiguously target α-synuclein aggregation/misfolding.

Vitamin E improved redox homeostasis in heart and aorta of hypothyroid rats

OBJECTIVES

The objective of this study was to evaluate the effect of vitamin E on the oxidative stress parameters and antioxidant defense enzymes in the heart and aorta of 6-n-propylthiouracil (PTU)-induced hypothyroid rats.

METHODS

The animals were divided into 4 experimental groups: Group 1 (Euthyroid) received tap water, Group 2 (Hypothyroid) received 0.05 % of PTU in dissolved in their drinking water, Group 3 (PTU+Vit E) hypothyroid rats treated with vitamin E, and Group 4 (Euthyroid+Vit E). Vitamin E was injected daily (20 mg/kg) to groups 3 and 4 via daily gavage for 6 weeks. Malondialdehyde (MDA) levels, total thiol levels, and the activities of Cu, Zn-superoxide dismutase (SOD) and catalase (CAT) were evaluated in the aortic and cardiac tissues.

RESULTS

A significant decrease of thyroxine (T4) serum levels confirmed hypothyroidism in rats, which received PTU. The MDA level increased and total thiol level decreased in the hypothyroid group compared to control group (p<0.001). Th e activities of SOD and CAT significantly decreased in the hypothyroid rats in comparison to the control. Vitamin E treatment resulted in increased levels of total thiol, SOD, and CAT within aortic and cardiac tissues and decreased levels of MDA in comparison with the hypothyroid group (p<0.01-p<0.001).

CONCLUSIONS

PTU-induced hypothyroidism resulted in oxidative stress. Chronic administration of vitamin E to hypothyroid rats decreased the oxidative stress markers in the aortic and cardiac tissues.

Fructose-Fed Rat Hearts are Protected Against Ischemia-Reperfusion Injury

High fructose-fed (HFF) rat model is known to develop the insulin-resistant syndrome with a very similar metabolic profile to the human X syndrome. Such metabolic modifications have been associated with a high incidence of cardiovascular disease. The role of free radical attack in diabetes mellitus and its cardiovascular complications have been abundantly documented. The present study examined the susceptibility to myocardial ischemic injury and the involvement of free radical attack and/or protection in the metabolic disorders of high FF rats. Rats were divided into two experimental groups that received diet for 4 weeks: a control group (C, n = 28) receiving a standard diet and a HFF group (FF, n = 28), in which 58% of the total carbohydrate was fructose. The euglycemic clamp technique was performed to assess insulin resistance. For the ischemia-reperfusion procedure, rat hearts were isolated and perfused at constant pressure before they were subjected to a 30-min occlusion of the left coronary artery followed by 120 mins of reperfusion. Hemodynamic parameters were measured throughout the protocol. Infarct-to-risk ratio (I/R) was assessed at the end of the protocol by 2,3,4-triphenyltetrazolium chloride staining and planimetric analysis. Lipid peroxidation, antioxidant enzyme activity, level of vitamin E, and trace element status were measured in blood samples from both groups. Rats of the FF group developed an insulin resistance indicated by the glucose infusion rate, which was decreased by 47%. Infarct size was significantly reduced in rats from the FF group (19.9% ± 6.6%) compared to rats from the control group (34.6% ± 4.9%), and cardiac functional recovery at reperfusion was improved in the FF group. Lipid peroxidation and oxidative stress were higher in the FF group, as indicated by higher malonedialdehyde level, whereas plasma vitamin E/triacylglycerol ratio was also enhanced in this group. This study indicates that fructose feeding affords protection against in vitro ischemia-reperfusion injury, potentially implicating vitamin E.

Antioxidants as potential medical countermeasures for chemical warfare agents and toxic industrial chemicals

The continuing horrors of military conflicts and terrorism often involve the use of chemical warfare agents (CWAs) and toxic industrial chemicals (TICs). Many CWA and TIC exposures are difficult to treat due to the danger they pose to first responders and their rapid onset that can produce death shortly after exposure. While the specific mechanism(s) of toxicity of these agents are diverse, many are associated either directly or indirectly with increased oxidative stress in affected tissues. This has led to the exploration of various antioxidants as potential medical countermeasures for CWA/TIC exposures. Studies have been performed across a wide array of agents, model organisms, exposure systems, and antioxidants, looking at an almost equally diverse set of endpoints. Attempts at treating CWAs/TICs with antioxidants have met with mixed results, ranging from no effect to nearly complete protection. The aim of this commentary is to summarize the literature in each category for evidence of oxidative stress and antioxidant efficacy against CWAs and TICs. While there is great disparity in the data concerning methods, models, and remedies, the outlook on antioxidants as medical countermeasures for CWA/TIC management appears promising.

Antioxidants in Cardiovascular Therapy: Panacea or False Hope?

Oxidative stress is a key feature of the atherothrombotic process involved in the etiology of heart attacks, ischemic strokes, and peripheral arterial disease. It stands to reason that antioxidants represent a credible therapeutic option to prevent disease progression and thereby improve outcome, but despite positive findings from in vitro studies, clinical trials have failed to consistently show benefit. The aim of this review is to re-appraise the concept of antioxidants in the prevention and management of cardiovascular disease. In particular, the review will explore the reasons behind failed antioxidant strategies with vitamin supplements and will evaluate how flavonoids might improve cardiovascular function despite bioavailability that is not sufficiently high to directly influence antioxidant capacity. As well as reaching conclusions relating to those antioxidant strategies that might hold merit, the major myths, limitations, and pitfalls associated with this research field are explored.

Infusion of docosahexaenoic acid protects against myocardial infarction

Most of the cardioprotective effects of long-chain omega 3 fatty acids, namely docosahexaenoic (DHA; 22:6n-3) and eicosapentaenoic (EPA; 20:5n-3), are due to their hypotriglyceridemic and anti-inflammatory effects, which lower the risk for cardiovascular disease and myocardial infarction. Little is known on the direct preventive activities of DHA and EPA on heart function. In isolated hearts, we studied (1) whether infused DHA is able to protect the heart from ischemia/reperfusion damage and (2) the role played by Notch-mediated signal transduction pathways in myocardial infarction. Perfusion with DHA before and before/after induction of ischemia reperfusion significantly diminished cardiac damage and afforded antioxidant protection. Mechanistically, infusion of DHA before and before/after the induction of ischemia differentially modulated the expression of Notch2 and 3 target genes. In particular, DHA increased the expression of Hey1 when infused pre- and pre/post-ischemia; Jagged 1 and the Notch2 receptors increased with DHA pre-ischemia, but not pre/post; Notch2 and 3 receptors as well as Delta increased following DHA administration pre- and (especially) pre/post-ischemia. In conclusion, while the precise nature of the Notch-mediated protection from ischemia/reperfusion afforded by DHA is as yet to be fully elucidated, our data add to the growing body of literature that indicates how systemic administration of DHA provides cardiovascular protection.

Neuroprotective effects of 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), an antioxidant in middle cerebral artery occlusion induced focal cerebral ischemia in rats

OBJECTIVES

In the present study, we have investigated the neuroprotective potential of 6hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), in middle cerebral artery occlusion (MCAO) induced focal cerebral ischemia.

METHODS

Sprague-Dawley rats were subjected to 2 hours of MCAO followed by 22 or 70 hours of reperfusion. After reperfusion, rats were evaluated for neurological deficits and cerebral infarction. Brain malondialdehyde (MDA) level and in situ terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling (TUNEL) were also estimated.

RESULTS

Focal cerebral ischemia produced a significant infarct volume and neurological scores as compared with sham-operated animals. Cerebral ischemia reperfusion injury was associated with an increase in lipid peroxidation in ipsilateral and contralateral hemisphere of brain along with an increase in TUNEL positive cells in ipsilateral hemisphere of brain sections indicating oxidative stress and DNA fragmentation, respectively. Trolox (10 and 30 mg/kg, i.p.) treatment significantly decreased neurological damage which was evident from the reduction in infarct volume and neurological score. Trolox (30 mg/kg) also attenuated oxidative stress and DNA fragmentation.

DISCUSSION

Oxidative stress-induced neuronal damage is implicated in the pathophysiology of cerebral ischemia. Our study suggests that Trolox is a potent neuroprotective agent in focal cerebral ischemia and its neuroprotective effects may be attributed to the reduction of lipid peroxidation and DNA fragmentation.

Altered pharmacokinetics of cimetidine caused by down-regulation of renal rat organic cation transporter 2 (rOCT2) after liver ischemia-reperfusion injury

The renal tubular secretion of cationic drugs is dominated by basolateral organic cation transporter 2 (rOCT2/SLC22A2) and luminal multidrug and toxin extrusion 1 (rMATE1/SLC47A1). Little is known about the variation in the expression of these renal transporters after liver ischemia-reperfusion (I/R) injury. Here, we examined the pharmacokinetics of a cationic drug, cimetidine, and renal rOCT2 and rMATE1 levels as well as their regulation after liver I/R. Rats were subjected to 60 min of liver ischemia followed by 12 h of reperfusion. The antioxidant Trolox was administered intravenously 5 min before reperfusion. The systemic and tubular secretory clearances of cimetidine (78% and 55%) as well as renal rOCT2 and rMATE1 levels (67% and 61%) in I/R rats were decreased compared with those in sham-operated rats, respectively. However, the renal tissue-to-plasma concentration ratio but not the renal tissue-to-urine clearance ratio of cimetidine was decreased after liver I/R. Moreover, Trolox prevented the decreases in renal rOCT2 levels and systemic clearance of cimetidine after liver I/R. These results demonstrate that liver I/R decreases the tubular secretion of cimetidine, mainly because of the decreased rOCT2 level in the kidney, and that oxidative stress should be responsible in part for decreased renal rOCT2 after liver I/R injury.

The cardioprotective effect of danshen and gegen decoction on rat hearts and cardiomyocytes with post-ischemia reperfusion injury

Background

Danshen (Salviae Miltiorrhizae Radix) and Gegen (Puerariae Lobatae Radix) have been used for treating heart disease for several thousand years in China. It has been found that a Danshen and Gegen decoction (DG) exhibiting an anti-atherosclerosis effect, which improves the patients’ heart function recovery. Pre-treatment with DG was reported to have protective effects on myocardium against ischemia/reperfusion injury. In the present study, we aim to investigate the post-treatment effect of DG on ischemic-reperfusion injuries ex vivo or in vitro and the underlying mechanisms involved.

Methods

The rat heart function in an ischemia and reperfusion (I/R) model was explored by examining three parameters including contractile force, coronary flow rate and the release of heart specific enzymes within the heart perfusate. In vitro model of hypoxia and reoxygenation (H/R), the protective effect of DG on damaged cardiomyocytes was investigated by examining the cell structure integrity, the apoptosis and the functionality of mitochondria.

Results

Our results showed that DG significantly improved rat heart function after I/R challenge and suppressed the release of enzymes by damaged heart muscles in a dose-dependent manner. DG also significantly inhibited the death of cardiomyocytes, H9c2 cells, with a H/R challenge. It obviously decreased cell apoptosis, protected the mitochondrial function and cell membrane skeleton integrity on H9c2 cells. The cardio-protection was also found to be related to a decrease in intracellular calcium accumulation within H9c2 cells after I/R challenge.

Conclusion

The potential application of DG in treating rat hearts with an I/R injury has been implied in this study. Our results suggested that DG decoction could act as an anti-apoptotic and anti-ion stunning agent to protect hearts against an I/R injury.

Biochemical factors modulating cellular neurotoxicity of methylmercury

Methylmercury (MeHg), an environmental toxicant primarily found in fish and seafood, poses a dilemma to both consumers and regulatory authorities, given the nutritional benefits of fish consumption versus the possible adverse neurological damage. Several studies have shown that MeHg toxicity is influenced by a number of biochemical factors, such as glutathione (GSH), fatty acids, vitamins, and essential elements, but the cellular mechanisms underlying these complex interactions have not yet been fully elucidated. The objective of this paper is to outline the cellular response to dietary nutrients, as well as to describe the neurotoxic exposures to MeHg. In order to determine the cellular mechanism(s) of toxicity, the effect of pretreatment with biochemical factors (e.g., N-acetyl cysteine, (NAC); diethyl maleate, (DEM); docosahexaenoic acid, (DHA); selenomethionine, SeM; Trolox) and MeHg treatment on intercellular antioxidant status, MeHg content, and other endpoints was evaluated. This paper emphasizes that the protection against oxidative stress offered by these biochemical factors is among one of the major mechanisms responsible for conferring neuroprotection. It is therefore critical to ascertain the cellular mechanisms associated with various dietary nutrients as well as to determine the potential effects of neurotoxic exposures for accurately assessing the risks and benefits associated with fish consumption.

Protective effects of antioxidants and anti-inflammatory agents against manganese-induced oxidative damage and neuronal injury

Exposure to excessive manganese (Mn) levels leads to neurotoxicity, referred to as manganism, which resembles Parkinson's disease (PD). Manganism is caused by neuronal injury in both cortical and subcortical regions, particularly in the basal ganglia. The basis for the selective neurotoxicity of Mn is not yet fully understood. However, several studies suggest that oxidative damage and inflammatory processes play prominent roles in the degeneration of dopamine-containing neurons. In the present study, we assessed the effects of Mn on reactive oxygen species (ROS) formation, changes in high-energy phosphates and associated neuronal dysfunctions both in vitro and in vivo. Results from our in vitro study showed a significant (p<0.01) increase in biomarkers of oxidative damage, F(2)-isoprostanes (F(2)-IsoPs), as well as the depletion of ATP in primary rat cortical neurons following exposure to Mn (500 μM) for 2h. These effects were protected when neurons were pretreated for 30 min with 100 of an antioxidant, the hydrophilic vitamin E analog, trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), or an anti-inflammatory agent, indomethacin. Results from our in vivo study confirmed a significant increase in F(2)-IsoPs levels in conjunction with the progressive spine degeneration and dendritic damage of the striatal medium spiny neurons (MSNs) of mice exposed to Mn (100mg/kg, s.c.) 24h. Additionally, pretreatment with vitamin E (100mg/kg, i.p.) or ibuprofen (140 μg/ml in the drinking water for two weeks) attenuated the Mn-induced increase in cerebral F(2)-IsoPs? and protected the MSNs from dendritic atrophy and dendritic spine loss. Our findings suggest that the mediation of oxidative stress/mitochondrial dysfunction and the control of alterations in biomarkers of oxidative injury, neuroinflammation and synaptodendritic degeneration may provide an effective, multi-pronged therapeutic strategy for protecting dysfunctional dopaminergic transmission and slowing of the progression of Mn-induced neurodegenerative processes.

Protective roles of cornuside in acute myocardial ischemia and reperfusion injury in rats

Cornuside is a secoiridoid glucoside isolated from the fruit of Cornus officinalis SIEB. et ZUCC. In this study, we investigated the anti-myocardial ischemia and reperfusion (I/R) injury effects of cornuside in vivo and elucidated the potential mechanism. Rat models of myocardial I/R were induced by coronary occlusion followed by reperfusion or by Isoproterenol (ISO), treatment of rats with cornuside (20 and 40 mg/kg, i.v.) protected the animals from myocardial I/R injury as indicated by a decrease in infarct volume, improvement in hemodynamics and reduction of myocardial damage severity. Treatment with cornuside also attenuated polymorphonuclear leukocytes (PMNs) infiltration, decreased myeloperoxidase (MPO) activity in the heart, lowered serum levels of pro-inflammatory factors and reduced phosphorylated IκB-α and nuclear factor kappa B (NF-κB) levels in the heart. Additionally, cornuside was shown to have remarkable antioxidant activity and inhibited ISO-induced myocardial cell necrosis. Thus, cornuside appeared to protect the rat from myocardial I/R injury by acting as an anti-inflammatory agent. These findings suggested that cornuside may be used therapeutically in the setting of myocardial I/R where inflammation and oxidant injury are prominent.

Cardioprotection with forsythoside B in rat myocardial ischemia-reperfusion injury: relation to inflammation response

The present study was undertaken to examine the effect of forsythoside B (FB) on rat myocardial ischemia-reperfusion (I/R) model and elucidate the potential mechanism. Left ventricular systolic pressure (LVSP) and +/-dp/dt(max) were detected. Blood samples were collected to determine serum levels of troponin T (Tn-T), TNF-alpha and IL-6. Hearts were harvested to assess histopathological change and infarct size, determine content of MDA, myeloperoxidase (MPO), SOD and GPx activities, analyze expression of high-mobility group box 1 (HMGB1), phosphor-I kappaB-alpha and phosphor-nuclear factor kappaB (NF-kappaB) in ischemic myocardial tissue by Western blot. Compared with control group, rats treatment with FB showed a significant recovery in myocardial function with improvement of LVSP and +/-dp/dt(max). The myocardial infarct volume, serum levels of Tn-T, TNF-alpha and IL-6, content of MDA and MPO activity in myocardial tissue were all reduced, protein expression of HMGB1, phosphor-I kappaB-alpha and phosphor-NF-kappaB were down-regulated, while attenuated the decrease of SOD and GPx activities. Besides, the infiltration of polymorph nuclear leukocytes (PMNs) and histopathological damages in myocardium were decreased in FB treated groups. These findings suggested that FB rescued cardiac function from I/R injury by limiting inflammation response and its antioxidant properties.

Oxidative stress is required for mechanical ventilation-induced protease activation in the diaphragm

Prolonged mechanical ventilation (MV) results in diaphragmatic weakness due to fiber atrophy and contractile dysfunction. Recent work reveals that activation of the proteases calpain and caspase-3 is required for MV-induced diaphragmatic atrophy and contractile dysfunction. However, the mechanism(s) responsible for activation of these proteases remains unknown. To address this issue, we tested the hypothesis that oxidative stress is essential for the activation of calpain and caspase-3 in the diaphragm during MV. Cause-and-effect was established by prevention of MV-induced diaphragmatic oxidative stress using the antioxidant Trolox. Treatment of animals with Trolox prevented MV-induced protein oxidation and lipid peroxidation in the diaphragm. Importantly, the Trolox-mediated protection from MV-induced oxidative stress prevented the activation of calpain and caspase-3 in the diaphragm during MV. Furthermore, the avoidance of MV-induced oxidative stress not only averted the activation of these proteases but also rescued the diaphragm from MV-induced diaphragmatic myofiber atrophy and contractile dysfunction. Collectively, these findings support the prediction that oxidative stress is required for MV-induced activation of calpain and caspase-3 in the diaphragm and are consistent with the concept that antioxidant therapy can retard MV-induced diaphragmatic weakness.

Antioxidant treatment of hindlimb-unloaded mouse counteracts fiber type transition but not atrophy of disused muscles

Oxidative stress was proposed as a trigger of muscle impairment in various muscle diseases. The hindlimb-unloaded (HU) rodent is a model of disuse inducing atrophy and slow-to-fast transition of postural muscles. Here, mice unloaded for 14 days were chronically treated with the selective antioxidant trolox. After HU, atrophy was more pronounced in the slow-twitch soleus muscle (Sol) than in the fast-twitch gastrocnemius and tibialis anterior muscles, and was absent in extensor digitorum longus muscle. In accord with the phenotype transition, HU Sol showed a reduced expression of myosin heavy chain type 2A (MHC-2A) and increase in MHC-2X and MHC-2B isoforms. In parallel, HU Sol displayed an increased sarcolemma chloride conductance related to an increased expression of ClC-1 channels, changes in excitability parameters, a positive shift of the mechanical threshold, and a decrease of the resting cytosolic calcium concentration. Moreover, the level of lipoperoxidation increased proportionally to the degree of atrophy of each muscle type. As expected, trolox treatment fully prevented oxidative stress in HU mice. Atrophy was not prevented but the drug significantly attenuated Sol phenotypic transition and excitability changes. Trolox treatment had no effect on control mice. These results suggest possible benefits of antioxidants in protecting muscle against disuse.

Melatonin and Trolox ameliorate duodenal LPS-induced disturbances and oxidative stress

BACKGROUND AND AIMS

Lipopolysaccharide evokes gastrointestinal motility disturbances and oxidative stress. The aims of the present study were to investigate the effect of melatonin and Trolox in the actions of lipopolysaccharide on duodenal contractility and on lipid peroxidation in rabbit duodenum.

METHODS

The in vitro duodenal contractility studies were carried out in organ bath and the levels of malondialdehyde were assayed by spectrophotometry. Duodenal segments were incubated with lipopolysaccharide (0.3 microg mL(-1)).

RESULTS

Lipopolysaccharide decreased acetylcholine-induced contractions and increased malondialdehyde and 4-hydroxyalkenals concentrations in homogenates of duodenum. Melatonin reduced the amplitude of spontaneous contractions in duodenal muscle. Acetylcholine-induced contractions were not altered by melatonin in longitudinal and circular muscles. Trolox decreased the amplitude of spontaneous contractions of duodenal muscle. Trolox (1.2 or 4 mM) did not alter acetylcholine-induced contractions in duodenal muscle, but the concentration of 12 mM diminished the frequency of contractions and acetylcholine-induced contractions. Melatonin (0.3 mM) or Trolox (4 mM) diminished malondialdehyde and 4-hydroxyalkenals levels induced by lipopolysaccharide in the duodenum.

CONCLUSIONS

Melatonin and Trolox reduce oxidative stress induced by lipopolysaccharide and ameliorate the effect of lipopolysaccharide on duodenal contractility.

Is oxidative stress a cause or consequence of disuse muscle atrophy in mice? A proteomic approach in hindlimb-unloaded mice

Two-dimensional proteomic maps of soleus (Sol), a slow oxidative muscle, and gastrocnemius (Gas), a fast glycolytic muscle of control mice (CTRL), of mice hindlimb unloaded for 14 days (HU mice) and of HU mice treated with trolox (HU-TRO), a selective and potent antioxidant, were compared. The proteomic analysis identified a large number of differentially expressed proteins in a pool of approximately 800 proteins in both muscles. The protein pattern of Sol and Gas adapted very differently to hindlimb unloading. The most interesting adaptations related to the cellular defense systems against oxidative stress and energy metabolism. In HU Sol, the antioxidant defense systems and heat shock proteins were downregulated, and protein oxidation index and lipid peroxidation were higher compared with CTRL Sol. In contrast, in HU Gas the antioxidant defense systems were upregulated, and protein oxidation index and lipid peroxidation were normal. Notably, both Sol and Gas muscles and their muscle fibres were atrophic. Antioxidant administration prevented the impairment of the antioxidant defense systems in Sol and further enhanced them in Gas. Accordingly, it restored normal levels of protein oxidation and lipid peroxidation in Sol. However, muscle and muscle fibre atrophy was not prevented either in Sol or in Gas. A general downsizing of all energy production systems in Sol and a shift towards glycolytic metabolism in Gas were observed. Trolox administration did not prevent metabolic adaptations in either Sol or Gas. The present findings suggest that oxidative stress is not a major determinant of muscle atrophy in HU mice.

Trolox ameliorates 3-nitropropionic acid-induced neurotoxicity in rats

3-nitropropionic acid (3-NPA) is a naturally occurring neurotoxin produced by legumes of the genus Astragalus and Arthrium fungi. Acute exposure to 3-NPA results in striatal astrocytic death and variety of behavior dysfunction in rats. Oxidative stress has been reported to play an important role in 3-NPA-induced neurotoxicity. Trolox is a potent free radical chain breaking antioxidant which has been shown to restore structure and function of the nervous system following oxidative stress. This rapid and efficient antioxidant property of trolox was attributed to its enhanced water solubility as compared with alpha-tocopherol. This investigation was aimed to study the effect of trolox against 3-NPA-induced neurotoxicity in female Wistar rats. The animals received trolox (0, 40 mg, 80 mg and 160 mg/kg, orally) daily for 7 days. 3-NPA (25mg/kg, i.p.) was administered daily 30 min after trolox for the same duration. One additional group of rats served as control (vehicle only). On day 8, the animals were observed for neurobehavioral performance. Immediately after behavioral studies, the animal's brains were dissected out for histological studies. Lesions in the striatal dopaminergic neurons were assessed by immunohistochemical method using tyrosine hydroxylase immunostaining. Administration of 3-NPA alone caused significant depletion of striatal dopamine and glutathione, whereas, the levels of thiobarbituric acid reactive substance (TBARS) and nitric oxide (NO) were significantly increased suggesting an elevated level of oxidative stress. Trolox significantly and dose-dependently protected animals against 3-NPA-induced neurobehavioral, neurochemical and structural abnormalities. These results clearly suggest that protective effect of trolox against 3-NPA-induced neurotoxicity is mediated through its free radical scavenging activity.

Antioxidant administration attenuates mechanical ventilation-induced rat diaphragm muscle atrophy independent of protein kinase B (PKB Akt) signalling

Oxidative stress promotes controlled mechanical ventilation (MV)-induced diaphragmatic atrophy. Nonetheless, the signalling pathways responsible for oxidative stress-induced muscle atrophy remain unknown. We tested the hypothesis that oxidative stress down-regulates insulin-like growth factor-1-phosphotidylinositol 3-kinase-protein kinase B serine threonine kinase (IGF-1-PI3K-Akt) signalling and activates the forkhead box O (FoxO) class of transcription factors in diaphragm fibres during MV-induced diaphragm inactivity. Sprague-Dawley rats were randomly assigned to one of five experimental groups: (1) control (Con), (2) 6 h of MV, (3) 6 h of MV with infusion of the antioxidant Trolox, (4) 18 h of MV, (5) 18 h of MV with Trolox. Following 6 h and 18 h of MV, diaphragmatic Akt activation decreased in parallel with increased nuclear localization and transcriptional activation of FoxO1 and decreased nuclear localization of FoxO3 and FoxO4, culminating in increased expression of the muscle-specific ubiquitin ligases, muscle atrophy factor (MAFbx) and muscle ring finger-1 (MuRF-1). Interestingly, following 18 h of MV, antioxidant administration was associated with attenuation of MV-induced atrophy in type I, type IIa and type IIb/IIx myofibres. Collectively, these data reveal that the antioxidant Trolox attenuates MV-induced diaphragmatic atrophy independent of alterations in Akt regulation of FoxO transcription factors and expression of MAFbx or MuRF-1. Further, these results also indicate that differential regulation of diaphragmatic IGF-1-PI3K-Akt signalling exists during the early and late stages of MV.

Renoprotective effect of trolox against ischaemia-reperfusion injury in rats

1. Although alpha-tocopherol has been shown to improve renal function following ischaemia-reperfusion (I/R) injury, its clinical use is not common because alpha-tocopherol requires several days of pretreatment to exhibit anti-oxidative benefits. The advent of trolox, a water-soluble analogue of alpha-tocopherol, has raised the possibility that this compound may function more rapidly during acute oxidative stress than the conventional alpha-tocopherol. 2. The present study was undertaken to determine the effects of the short-term administration of trolox on renal excretory function following I/R in rats. 3. Male Wistar rats were subjected to 45 min unilateral renal artery occlusion followed by 120 min reperfusion. The control I/R group was subjected to I/R and received saline as an intravenous bolus (2 mL/kg) followed by a continuous infusion of 2 mL/kg per h starting 30 min before ischaemia, whereas the three trolox-treated I/R groups were given an i.v. bolus of trolox (2.5 mg/kg) followed by a continuous infusion (12 mg/kg per h) starting at 30 min before ischaemia, 5 min before reperfusion and 5 min after reperfusion, respectively. Renal function, malondialdehyde, glutathione and histopathology were evaluated. 4. Ischaemia-reperfusion produced a significant deterioration of renal function, which was accompanied by an elevated malondialdehyde and depleted glutathione content. Kidneys from control I/R rats demonstrated tubular cell transformation, brush border loss, vacuolation, cast formation and tubular obstruction. These changes were attenuated by trolox treatment, with the best improvement achieved when trolox was delivered 5 min before reperfusion. 5. The results demonstrate the renoprotective effects of the short-term administration of trolox on I/R injury. These findings indicate the ability of trolox to overcome a major drawback of using alpha-tocopherol and suggest that trolox may offer a therapeutic advantage over alpha-tocopherol in acute ischaemic renal failure settings.

'In vitro' protective effect of a hydrophilic vitamin E analogue on the decrease in levels of elongation factor 2 in conditions of oxidative stress

BACKGROUND

Protein synthesis is inhibited by oxidative stress. Among the possible causes of this inhibition are the modifications of elongation factor 2 (eEF-2), the protein that catalyzes the translocation of the ribosome through mRNA. eEF-2 is extremely sensitive to oxidative stress caused mainly by lipid peroxidant compounds such as cumene hydroperoxide (CH).

OBJECTIVE

The purpose of this study was to determine whether the antioxidant Trolox prevents the effect of CH on the levels of hepatic eEF-2.

METHODS

The effect was determined in liver homogenates treated with both compounds. Lipid peroxides and carbonyl content were also measured.

RESULTS

The results show that Trolox at certain doses prevents the decrease in the level of eEF-2 caused by CH.

CONCLUSION

Under oxidative stress circumstances, vitamin E can prevent the effect of oxidations on relevant biological processes such as protein synthesis.

Free radical scavenger and antioxidant capacity correlation of alpha-tocopherol and Trolox measured by three in vitro methodologies

The objective of this study was to correlate the free radical scavenging and antioxidant activity of two known substances (Trolox and alpha-tocopherol), using three in vitro methods (linoleic acid emulsion, brain homogenate and 2,2-diphenyl-1-picryl-hydrazyl [DPPH]). At steady state, alpha-tocopherol showed a greater inhibition of spontaneous oxidation of brain homogenate (59.42%+/-1.91) than Trolox (38.50%+/-2.38), while the latter showed a better antioxidant activity performance regarding inhibition of linoleic acid peroxidation (100% versus 84.02%+/-1.98) and free radical scavenging activity (93.56%+/-5.71 versus 66.72%+/-6.28). When the IC50 value was used as a parameter, alpha-tocopherol presented greater antioxidant activity than Trolox evaluated in brain homogenate and DPPH, without a significant difference when using linoleic acid emulsion. Both compounds showed the same antioxidant efficiency measured by DPPH kinetics (0.37 mM). Antioxidant activity significantly changed according to the substrate, the parameter adopted to compare the substances in the same method and the form used to express antioxidant concentration.

Synthesis of 7-hydroxy-4-Oxo-4H-chromene- and 7-hydroxychroman-2-carboxylic acidN-alkyl amides and their antioxidant activities

A series of 7-hydroxy-4-oxo-4H-chromene- (3a - h) and 7-hydroxychroman-2-carboxylic acid N-alkyl amides (4a - g) were synthesized and their antioxidant activities were evaluated. While compounds 3a - h were less active, compounds 4a - g exhibited more potent inhibition of lipid peroxidation initiated by Fe2+ and ascorbic acid in rat brain homogenates. Among them, 7-hydroxychroman-2-carboxylic acid N-alkylamides (4e - g) bearing nonyl, decyl, and undecyl side chain exhibited 3 times more potent inhibition than trolox (1).

Neuroprotective effects of trolox in global cerebral ischemia in gerbils

Stroke is a third leading cause of death and oxygen free radicals have been shown to be involved in its pathophysiology. In the present study, we have investigated neuroprotective potential of trolox, a free radical scavenger in bilateral carotid arteries occlusion (5 min) model of global cerebral ischemia in Mongolian gerbils. Gerbils were treated with trolox (3, 10 or 30 mg/kg, i.p.) 30 min prior to occlusion. There was a significant increase in neurological symptoms and locomotor activity in ischemic animals as compared with the sham-operated animals. These effects were attenuated by trolox 30 mg/kg, i.p. Significant increase in the number of the surviving neurons in the hippocampal CA1 pyramidal region was observed in ischemic animals treated with trolox 30 mg/kg, i.p. There was significant increase in the level of malondialdehyde (MDA) in ischemic animals indicating oxidative stress. Elevated levels of MDA in ischemic animals (25.79+/-3.34 microM/mg of protein) were reduced (16.43+/-3.32 microM/mg of protein) and (8.98+/-0.89 microM/mg of protein) by trolox 10 and 30 mg/kg, i.p., respectively. This study demonstrates the neuroprotective potential of trolox in global cerebral ischemia in gerbils.

Inhibitory effect of chroman carboxamide on interleukin-6 expression in response to lipopolysaccharide by preventing nuclear factor-kappaB activation in macrophages

6-Hydroxy-7-methoxychroman-2-carboxylic acid (3-nitrophenyl)amide (CP-1158) is a synthetic chroman carboxamide with trolox-like chemical structure. In the present study, CP-1158 was found to inhibit interleukin (IL)-6 production in lipopolysaccharide (LPS)-stimulated macrophages RAW 264.7. The CP-1158 attenuated LPS-induced synthesis of IL-6 transcript but also inhibited LPS-induced IL-6 promoter activity. Further, CP-1158 attenuated LPS-induced syntheses of tumor necrosis factor (TNF)-alpha, IL-1beta, interferon-inducible protein (IP)-10 and macrophage inflammatory protein (MIP)-1beta transcripts. Nuclear factor (NF)-kappaB has been evidenced to play a major mechanism in LPS-induced expression of IL-6 or other inflammatory cytokines. CP-1158 prevented LPS-induced nuclear translocation of NF-kappaB complex and subsequently inhibited DNA binding activity of NF-kappaB complex as well as NF-kappaB transcriptional activity in macrophages RAW 264.7. However, CP-1158 did not affect LPS-induced phosphorylation and degradation of inhibitory kappaB (IkappaB). In another experiment, CP-1158 inhibited IL-6 promoter activity elicited by expression vectors encoding NF-kappaB p50 or p65 subunit. Taken together, CP-1158 inhibited LPS-induced expression of inflammatory cytokines including IL-6, targeting NF-kappaB activating pathway downstream IkappaB degradation, and thus could provide an anti-inflammatory potential of chroman carboxamide.

Control of oxidative stress in small bowel: relevance to organ preservation

BACKGROUND

Oxidative stress during cold small bowel (SB) storage has not been investigated because oxygen is depleted rapidly after procurement. We hypothesized that oxidative catabolism facilitated by a proven amino acid-based (AA) storage solution promotes oxidative stress; furthermore, there is an important role for antioxidant supplementation during cold storage.

METHODS

SB from Sprague-Dawley rats (n = 6 in each group) were procured according to standardized procedures involving vascular flush with modified University of Wisconsin solution and luminal treatment with an AA-based solution proven previously to aid preservation. SB were assigned randomly to the following antioxidant treatment groups: group 1, none; group 2, superoxide dismutase/catalase; group 3, 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox, a water-soluble analogue of vitamin E). Energetics, oxidative stress, electrophysiology, and histology were assessed over 24 hours at 4 degrees C.

RESULTS

The addition of Trolox in group 3 resulted in a significant reduction in malondialdehyde levels compared with all other groups throughout 24 hours of cold storage. Tissue energetics correlated well with reduced oxidative injury; over the first 12 hours, adenosine triphosphate and total adenylates were superior in tissues treated with Trolox (group 3) versus AA solution alone (group 1). Functional assessment showed relatively normal permeability in all groups, however, Trolox-treated tissues showed significantly higher short-circuit current compared with control group (17.7 vs 5.5 microA/cm(2)). Histologic integrity was improved in group 3 after 24 hours of cold storage.

CONCLUSIONS

Oxidative stress appears to be a determinant in the pathogenesis of mucosal injury during cold storage. Trolox effectively abrogates storage-related oxidative stress in SB.

Antisecretory and antiulcer effects of diphenyl diselenide

The antisecretory and antiulcer effects of diphenyl diselenide were studied in vivo and in vitro. Diphenyl diselenide, administered intraperitoneally prevented the development of gastric lesions induced by ethanol and indomethacin. There was no difference in plasma uric acid concentrations in diphenyl diselenide-treated rats with gastric lesions induced by 70% ethanol. There were no changes in TBARS levels in diphenyl diselenide-treated rats with gastric lesions induced by indomethacin and ethanol. Diphenyl diselenide (5, 10 and 50mg/kg) inhibited gastric acid secretion in pylorus-ligated rats. In vitro results demonstrated that diphenyl diselenide inhibited lipid peroxidation induced by Fe(2+)/ascorbate/H(2)O(2) and reduced K(+)-dependent ATPase activity. The mechanisms by which pre-administered diselenide protects the damaged area in the gastric mucosa are not clear but it appears that the antiulcer activity of diphenyl diselenide is the result of antisecretory activity, via inhibition of gastric K(+)-ATPase activity.

Preparation of 2,3-dihydroselenolo[2,3-b]pyridines and related compounds by free-radical means

Photolysis of the thiohydroximate ester derivative 21 of 2-carboethoxy-2-(2-(benzylseleno)pyridin-3-yl)tridecylcarboxylic acid (20) affords 2-dodecyl-2-carboethoxy-2,3-dihydroselenolo[2,3-b]pyridine (22) in 89% yield in a process presumably involving intramolecular homolytic substitution by a tertiary alkyl radical at selenium with loss of a benzyl radical. Alternatively, rearrangement of O-(omega-haloalkyl)esters 34 of 2-carboethoxy-N-hydroxypyridine-2-selone affords azonianaphthalenium halides 37 in 79% yield.

Screening of antioxidants from medicinal plants for cardioprotective effect against doxorubicin toxicity

Doxorubicin is an important and effective anticancer drug widely used for the treatment of various types of cancer but its clinical use is limited by dose-dependent cardiotoxicity. Elevated tissue levels of cellular superoxide anion/oxidative stress are a mechanism by which doxorubicin-induced cardiotoxicity. Selected medicinal plant extracts were tested for their antioxidant capacity and cardioprotective effect against doxorubicin-induced cardiotoxicity. The cardiac myoblasts H9c2 were incubated with the antioxidants ascorbic acid, trolox, N-acetylcysteine or selected medicinal plant extracts including; 1) ethanolic extracts from Curcuma longa L-EtOH Phyllanthus emblica L-EtOH, and Piper rostratum Roxb-EtOH; and 2) water extracts from Curcuma longa L-H2O and Morus alba L-H2O. The cardioprotective effects of these extracts were evaluated by crystal violet cytotoxicity assay. IC50s of doxorubicin were compared in the presence or absence of ascorbic acids, trolox, N-acetylcysteine or plant extracts. Morus alba L-H2O showed the highest antioxidant properties evaluated by ferric reducing/antioxidant power assay. Ascorbic acid and N-acetylcysteine had modest effects on the protection of doxorubicin-induced cytotoxicity while trolox showed insignificant protective effect. All plant extracts protected cardiac toxicity at different degrees except that Curcuma longa L-EtOH had no protective effect. Phyllanthus emblica-EtOH (100 microg/ml) showed the highest cardioprotective effect (approximately 12-fold doxorubicin IC50 increase). The data demonstrate that antioxidants from natural sources may be useful in the protection of cardiotoxicity in patients who receive doxorubicin.