Syzygium cumini leaf extract protects macrophages against the oxidized LDL-induced toxicity: A promising atheroprotective effect.

Oxidized LDL (oxLDL) plays a pivotal role on atherosclerosis development, mainly in the formation of lipid-laden macrophage "foam cells". As a consequence, substances that can modulate LDL oxidation have a pharmacological and therapeutic relevance. Based in previous findings showing the ability of Syzigium cumini leaf extract (ScExt) in preventing LDL oxidation in vitro, this study was aimed to assess the effects of ScExt on oxLDL-mediated toxicity in murine J774 macrophages-like cells. For biochemical analyses, LDL isolated from fresh human plasma and oxidized with CuSO4 was incubated with ScExt pre-treated macrophages. Our results demonstrated that ScExt was efficient in preventing the overproduction of reactive oxygen/nitrogen species (ROS/RNS), the loss of macrophage's viability and the foam cells formation induced by oxLDL. These protective effects of ScExt make it a promising antioxidant for future trials toward atherogenesis.

Methylglyoxal disturbs DNA repair and glyoxalase I system in Saccharomyces cerevisiae.

Methylglyoxal (MG) is a highly reactive aldehyde able to form covalent adducts with proteins and nucleic acids, disrupting cellular functions. In this study, we performed a screening of Saccharomyces cerevisiae (S. cerevisiae) strains to find out which genes of cells are responsive to MG, emphasizing genes against oxidative stress and DNA repair. Yeast strains were grown in the YPD-Galactose medium containing MG (0.5 to 12 mM). The tolerance to MG was evaluated by determining cellular growth and cell viability. The toxicity of MG was more pronounced in the strains with deletion in genes engaged with DNA repair checkpoint proteins, namely Rad23 and Rad50. MG also impaired the growth and viability of S. cerevisiae mutant strains Glo1 and Gsh1, both components of the glyoxalase I system. Differently, the strains with deletion in genes encoding for antioxidant enzymes were apparently resistant to MG. In summary, our data indicate that DNA repair and MG detoxification pathways are keys in the control of MG toxicity in S. cerevisiae.

Pequi enriched diets protect Drosophila melanogaster against paraquat-induced locomotor deficits and oxidative stress.

The species Caryocar coriaceum Wittm (C. coriaceum), is popularly employed in northeast of Brazil for culinary purposes and in folk medicine. The oil from its fruit, deignated Pequi, is commonly used to treat inflammatory problems, and its leaves to treat viral infections. However, comprehensive knowledge regarding the pharmacological properties attributed to these plant parts is still scarce. Thus, this study aimed to explore the in vivo antioxidant potential of aqueous extract of the leaves (AEL) and Pequi pulp oil (PPO) on the pro-oxidative effects induced by paraquat (PQ) using Drosophila melanogaster (D. melanogaster) as a model. These flies were fed with either standard or AEL and PPO supplemented diets prior to (pre-treatment for 7 days) or concomitantly (co-treatment for 5 days) with PQ. D. melanogaster administered PQ exhibited locomotor deficits and a higher rate of mortality. PQ induced significant changes in the antioxidant/oxidant status of D. melanogaster, including significant (1) increase in levels of reactive oxygen species (ROS) and lipid peroxidation; (2) elevation in the activity of antioxidant enzymes catalase (CAT) and glutathione-S-transferase (GST) and marked up-regulation in mRNA expression of stress-related genes for CAT, superoxide dismutase (SOD), thioredoxin reductase and Keap-1. Aside for mortality rates, AEL and PPO treatments reduced PQ-induced oxidative stress and motor impairments. No apparent evidence of toxicity was observed in D. melanogaster fed with AEL and PPO alone. Our findings provide evidence that AEL and PPO may confer protection against oxidant conditions by stimulating antioxidant responses.

Resveratrol Protects Against Vacuous Chewing Movements Induced by Chronic Treatment with Fluphenazine.

Typical antipsychotics, which are commonly used to treat schizophrenia, cause motor disorders such as tardive dyskinesia (TD) in humans and orofacial dyskinesia (OD) in rodents. The disease mechanisms as well as treatment effectiveness are still unknown. In this study, we investigated the effect of resveratrol, a polyphenol with neuroprotective properties, on behavioral changes induced by chronic treatment with fluphenazine in rats and the possible relationship between monoamine oxidase (MAO) activity and vacuous chewing movements (VCMs). Rats were treated for 18 weeks with fluphenazine enantate [25 mg/kg, intramuscularly (i.m.), every 21 days] and/or resveratrol (20 mg/kg, offered daily in drinking water). Next, body weight gain, behavioral parameters (VCMs and open field tests-locomotor and rearing activity), and MAO activity were evaluated. Fluphenazine treatment reduced body weight gain, number of crossings and rearings, and the co-treatment with resveratrol did not affect these alterations. Fluphenazine increased the prevalence and intensity of VCMs and the co-treatment with resveratrol reduced the VCMs. Furthermore, a negative correlation was found between the number of VCMs and MAO-B activity in the striatum of rats. Our data suggest that resveratrol could be promissory to decrease OD. Moreover, MAO-B activity in the striatum seems to be related to VCMs intensity.

Effect of Syzygium cumini and Bauhinia forficata aqueous-leaf extracts on oxidative and mitochondrial parameters in vitro.

Aqueous-leaf extract of Syzygium cumini and Bauhinia forficata are traditionally used in the treatment of diabetes and cancer, especially in South America, Africa, and Asia. In this study, we analyzed the effects of these extracts on oxidative and mitochondrial parameters in vitro, as well as their protective activities against toxic agents. Phytochemical screenings of the extracts were carried out by HPLC analysis. The in vitro antioxidant capacities were compared by DPPH radical scavenging and Fe(2+) chelating activities. Mitochondrial parameters observed were swelling, lipid peroxidation and dehydrogenase activity. The major chemical constituent of S. cumini was rutin. In B. forficata were predominant quercetin and gallic acid. S. cumini reduced DPPH radical more than B. forficata, and showed iron chelating activity at all tested concentrations, while B. forficata had not similar property. In mitochondria, high concentrations of B. forficata alone induced a decrease in mitochondrial dehydrogenase activity, but low concentrations of this extract prevented the effect induced by Fe(2+)+H2O2. This was also observed with high concentrations of S. cumini. Both extracts partially prevented the lipid peroxidation induced by Fe(2+)/citrate. S. cumini was effective against mitochondrial swelling induced by Ca(2+), while B. forficata alone induced swelling more than Ca(2+). This study suggests that leaf extract of S. cumini might represent a useful therapeutic for the treatment of diseases related with mitochondrial dysfunctions. On the other hand, the consumption of B. forficata should be avoided because mitochondrial damages were observed, and this possibly may pose risk to human health.

Diphenyl diselenide modulates gene expression of antioxidant enzymes in the cerebral cortex, hippocampus and striatum of female hypothyroid rats.

INTRODUCTION: Cellular antioxidant signaling can be altered either by thyroid disturbances or by selenium status. AIMS: To investigate whether or not dietary diphenyl diselenide can modify the expression of genes of antioxidant enzymes and endpoint markers of oxidative stress under hypothyroid conditions. METHODS: Female rats were rendered hypothyroid by continuous exposure to methimazole (MTZ; 20 mg/100 ml in the drinking water) for 3 months. Concomitantly, MTZ-treated rats were either fed or not with a diet containing diphenyl diselenide (5 ppm). mRNA levels of antioxidant enzymes and antioxidant/oxidant status were determined in the cerebral cortex, hippocampus and striatum. RESULTS: Hypothyroidism caused a marked upregulation in mRNA expression of catalase, superoxide dismutase (SOD-1, SOD-3), glutathione peroxidase (GPx-1, GPx-4) and thioredoxin reductase (TrxR-1) in brain structures. SOD-2 was increased in the cortex and striatum, while TrxR-2 increased in the cerebral cortex. The increase in mRNA expression of antioxidant enzymes was positively correlated with the Nrf-2 transcription in the cortex and hippocampus. Hypothyroidism caused oxidative stress, namely an increase in lipid peroxidation and reactive oxygen species levels in the hippocampus and striatum, and a decrease in nonprotein thiols in the cerebral cortex. Diphenyl diselenide was effective in reducing brain oxidative stress and normalizing most of the changes observed in gene expression of antioxidant enzymes. CONCLUSION: The present work corroborates and extends that hypothyroidism disrupts antioxidant enzyme gene expression and causes oxidative stress in the brain. Furthermore, diphenyl diselenide may be considered a promising molecule to counteract these effects in a hypothyroidism state.

Caffeine intake may modulate inflammation markers in trained rats.

Caffeine is presented in many commercial products and has been proven to induce ergogenic effects in exercise, mainly related to redox status homeostasis, inflammation and oxidative stress-related adaptation mechanisms. However, most studies have mainly focused on muscle adaptations, and the role of caffeine in different tissues during exercise training has not been fully described. The aim of this study was therefore, to analyze the effects of chronic caffeine intake and exercise training on liver mitochondria functioning and plasma inflammation markers. Rats were divided into control, control/caffeine, exercise, and exercise/caffeine groups. Exercise groups underwent four weeks of swimming training and caffeine groups were supplemented with 6 mg/kg/day. Liver mitochondrial swelling and complex I activity, and plasma myeloperoxidase (MPO) and acetylcholinesterase (AChE) activities were measured. An anti-inflammatory effect of exercise was evidenced by reduced plasma MPO activity. Additionally, caffeine intake alone and combined with exercise decreased the plasma AChE and MPO activities. The per se anti-inflammatory effect of caffeine intake should be highlighted considering its widespread use as an ergogenic aid. Therefore, caffeine seems to interfere on exercise-induced adaptations and could also be used in different exercise-related health treatments.

Diphenyl diselenide supplementation reduces biochemical alterations associated with oxidative stress in rats fed with fructose and hydrochlorothiazide.

The study evaluated whether a diet containing diphenyl diselenide (PhSe)2, a synthetic antioxidant, could reduce the biochemical alterations induced by chronic consumption of highly enriched fructose diet and/or hydrochlorothiazide (HCTZ). Rats were fed a control diet (CT) or a high fructose diet (HFD), supplemented with or not HCTZ (4.0g/kg) and/or (PhSe)2 (3ppm) for 18weeks. HFD intake increased significantly plasma glucose, fructosamine, triglycerides and cholesterol levels. (PhSe)2 supplementation significantly reduced triglycerides and cholesterol but could not restore them to control levels. The combination of HFD and HCTZ significantly altered plasma glucose, fructosamine, triglycerides and cholesterol levels which were not restore by (PhSe)2 supplementation. Lipid peroxidation, protein carbonyl formation, vitamin C level and catalase activity decreased after HFD, HCTZ or HFD plus HCTZ ingestion. Remarkably (PhSe)2 supplementation restored the oxidative stress parameters. HCTZ decreased renal superoxide dismutase (SOD) activity, which was restored to control levels by (PhSe)2. Furthermore, the association of HFD and HCTZ decreased plasma potassium levels and aggravated HCTZ-induced hypomagnesemia and hypertriglyceridemia. Here we provided evidence of the involvement of oxidative stress and metabolic disorders in a rat model of HFD associated or not with HTCZ. (PhSe)2 supplementation reduced the oxidative stress and this compound should be considered for the treatment of biochemical disturbances and oxidative stress in other animal models of metabolic disorders.

Role of calcium and mitochondria in MeHg-mediated cytotoxicity.

Methylmercury (MeHg) mediated cytotoxicity is associated with loss of intracellular calcium (Ca²âº) homeostasis. The imbalance in Ca²âº physiology is believed to be associated with dysregulation of Ca²âº intracellular stores and/or increased permeability of the biomembranes to this ion. In this paper we summarize the contribution of glutamate dyshomeostasis in intracellular Ca²âº overload and highlight the mitochondrial dysfunctions induced by MeHg via Ca²âº overload. Mitochondrial disturbances elicited by Ca²âº may involve several molecular events (i.e., alterations in the activity of the mitochondrial electron transport chain complexes, mitochondrial proton gradient dissipation, mitochondrial permeability transition pore (MPTP) opening, thiol depletion, failure of energy metabolism, reactive oxygen species overproduction) that could culminate in cell death. Here we will focus on the role of oxidative stress in these phenomena. Additionally, possible antioxidant therapies that could be effective in the treatment of MeHg intoxication are briefly discussed.

Effect of different oximes on rat and human cholinesterases inhibited by methamidophos: a comparative in vitro and in silico study.

Methamidophos is one of the most toxic organophosphorus (OP) compounds. It acts via phosphorylation of a serine residue in the active site of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), leading to enzyme inactivation. Different oximes have been developed to reverse this inhibition. Thus, our work aimed to test the protective or reactivation capability of pralidoxime and obidoxime, as well as two new oximes synthesised in our laboratory, on human and rat cholinesterases inhibited by methamidophos. In addition, we performed molecular docking studies in non-aged methamidophos-inhibited AChE to understand the mechanisms involved. Our results suggested that pralidoxime protected and reactivated methamidophos-inhibited rat brain AChE. Regarding human erythrocyte AChE, all oximes tested protected and reactivated the enzyme, with the best reactivation index observed at the concentration of 50 µM. Concerning BChE, butane-2,3-dionethiosemicarbazone oxime (oxime 1) was able to protect and reactivate the methamidophos-inhibited BChE by 45% at 50 µM, whereas 2(3-(phenylhydrazono)butan-2-one oxime (oxime 2) reactivated 28% of BChE activity at 100 µM. The two classical oximes failed to reactivate BChE. The molecular docking study demonstrated that pralidoxime appears to be better positioned in the active site to attack the O-P moiety of the inhibited enzyme, being near the oxyanion hole, whereas our new oximes were stably positioned in the active site in a manner similar to that of obidoxime. In conclusion, our work demonstrated that the newly synthesised oximes were able to reactivate not only human erythrocyte AChE but also human plasma BChE, which could represent an advantage in the treatment of OP compounds poisoning.

The effects of diphenyl diselenide on oxidative stress biomarkers in Cyprinus carpio exposed to herbicide quinclorac (Facet®).

The occurrence of pollutants in the aquatic environment can produce severe toxic effects on non-target organisms, including fish. These sources of contamination are numerous and include herbicides, which represent a large group of toxic chemicals. Quinclorac, an herbicide widely applied in agriculture, induces oxidative stress due to free radical generation and changes in the antioxidant defense system. The aim of this study was to assess if dietary diphenyl diselenide (PhSe)2 has a protective effect in tissues of fish species Cyprinus carpio exposed to the quinclorac herbicide. The fish were fed with either a standard or a diet containing 3.0 mg/Kg of diphenyl diselenide for 60 d. After were exposed to 1 mg/L of Facet® (quinclorac commercial formulation) for 192 h. At the end of the experimental period, parameters as thiobarbituric acid-reactive substance levels (TBARS), protein carbonyl, catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), nonprotein thiols (NPSH) and ascorbic acid in the liver, gills, brain and muscle were evaluated in Cyprinus carpio. In fish exposed to quinclorac and feeding with standard diet TBARS levels increased in liver and gills. However, SOD activity decreases in liver whereas no alterations were observed in catalase activity in this tissue. Quinclorac also decrease GST activity in liver and brain, NPSH in brain and muscle and ascorbic acid in muscle. Concerning protein carbonyl exposed to herbicide the fish did not show any alterations. The diphenyl diselenide supplemented diet reversed these effects, preventing increases in TBARS levels in liver and gills. GST activity was recovered to control values in liver. NPSH levels in brain and muscle increased remain near to control values. These results indicated that dietary diphenyl diselenide protects tissues against quinclorac induced oxidative stress ameliorating the antioxidant properties.

Isatin-3-N4-benzilthiosemicarbazone, a non-toxic thiosemicarbazone derivative, protects and reactivates rat and human cholinesterases inhibited by methamidophos in vitro and in silico.

Organophosphates (OPs), which are widely used as pesticides, are acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitors. The inactivation of AChE results in the accumulation of acetylcholine at cholinergic receptor sites, causing a cholinergic crisis that can lead to death. The classical treatment for OP poisoning is administration of oximes, but these compounds are ineffective in some cases. Here we determined whether the new compound isatin-3-N(4)-benzilthiosemicarbazone (IBTC), which in our previous study proved to be an antioxidant and antiatherogenic molecule, could protect and reactivate AChE and BChE. Toxicity of IBTC after subcutaneous injection in mice was measured using assays for oxidized diclorofluoresceine (DCF), thiobarbituric acid reactive substances (TBARS), non-protein thiol (NPSH) levels, and catalase (CAT), sodium potassium (Na(+)/K(+)) ATPase, delta-aminolevulinic acid dehydratase (ALA-D), and glutathione peroxidases (GPx) enzyme activities. The cytotoxicity was evaluated and the enzymatic activity of cholinesterase was measured in human blood samples. Molecular docking was used to predict the mechanism of IBTC interactions with the AChE active site. We found that IBTC did not increase the amount of DCF-RS or TBARS, did not reduce NPSH levels, and did not increase CAT, (Na(+)/K(+)) ATPase, ALA-D, or GPx activities. IBTC protected and reactivated both AChE and BChE activities. Molecular docking predicted that IBTC is positioned at the peripheral anionic site and in the acyl binding pocket of AChE and can interact with methamidophos, releasing the enzyme's active site. Our results suggest that IBTC, besides being an antioxidant and a promising antiatherogenic agent, is a non-toxic molecule for methamidophos poisoning treatment.

Antioxidant activity of ß-selenoamines and their capacity to mimic different enzymes.

The antioxidant properties of organoselenium compounds have been extensively investigated because oxidative stress is a hallmark of a variety of chronic human diseases. Here, we reported the influence of substituent groups in the antioxidant activity of ß-selenoamines. We have investigated whether they exhibited glutathione peroxidase-like (GPx-like) activity and whether they could be substrate of thioredoxin reductase (TrxR). In the DPPH assay, the ß-selenium amines did not exhibit antioxidant activity. However, the ß-selenium amines with p-methoxy and tosyl groups prevented the lipid peroxidation. The ß-selenium amine compound with p-methoxy substituent group exhibited thiol-peroxidase-like activity (GPx-like activity) and was reduced by the hepatic TrxR. These results contribute to understand the influence of structural alteration of non-conventional selenium compounds as synthetic mimetic of antioxidant enzymes of mammalian organisms.

Modulation of methylmercury uptake by methionine: prevention of mitochondrial dysfunction in rat liver slices by a mimicry mechanism.

Methylmercury (MeHg) is an ubiquitous environmental pollutant which is transported into the mammalian cells when present as the methylmercury-cysteine conjugate (MeHg-Cys). With special emphasis on hepatic cells, due to their particular propensity to accumulate an appreciable amount of Hg after exposure to MeHg, this study was performed to evaluate the effects of methionine (Met) on Hg uptake, reactive species (RS) formation, oxygen consumption and mitochondrial function/cellular viability in both liver slices and mitochondria isolated from these slices, after exposure to MeHg or the MeHg-Cys complex. The liver slices were pre-treated with Met (250 µM) 15 min before being exposed to MeHg (25 µM) or MeHg-Cys (25 µM each) for 30 min at 37 °C. The treatment with MeHg caused a significant increase in the Hg concentration in both liver slices and mitochondria isolated from liver slices. Moreover, the Hg uptake was higher in the group exposed to the MeHg-Cys complex. In the DCF (dichlorofluorescein) assay, the exposure to MeHg and MeHg-Cys produced a significant increase in DFC reactive species (DFC-RS) formation only in the mitochondria isolated from liver slices. As observed with Hg uptake, DFC-RS levels were significantly higher in the mitochondria treated with the MeHg-Cys complex compared to MeHg alone. MeHg exposure also caused a marked decrease in the oxygen consumption of liver slices when compared to the control group, and this effect was more pronounced in the liver slices treated with the MeHg-Cys complex. Similarly, the loss of mitochondrial activity/cell viability was greater in liver slices exposed to the MeHg-Cys complex when compared to slices treated only with MeHg. In all studied parameters, Met pre-treatment was effective in preventing the MeHg- and/or MeHg-Cys-induced toxicity in both liver slices and mitochondria. Part of the protection afforded by Met against MeHg may be related to a direct interaction with MeHg or to the competition of Met with the complex formed between MeHg and endogenous cysteine. In summary, our results show that Met pre-treatment produces pronounced protection against the toxic effects induced by MeHg and/or the MeHg-Cys complex on mitochondrial function and cell viability. Consequently, this amino acid offers considerable promise as a potential agent for treating acute MeHg exposure.

Complex methylmercury-cysteine alters mercury accumulation in different tissues of mice.

Methylmercury (MeHg) can cause deleterious effects in vertebrate tissues, particularly in the central nervous system. MeHg interacts with sulfhydryl groups from low and high molecular weight thiols in the blood, which can facilitate MeHg uptake into different tissues. The purpose of this study was to examine the effect of MeHg-Cysteine (MeHg-Cys) complex administration on Hg-uptake in cerebral areas (cortex and cerebellum), liver and kidney of adult mice. Animals were divided into four groups: control (1 mL/kg distilled water), MeHg (2 mg/kg), Cys (2 mg/kg) and MeHg-Cys complex (0.8 molar ratio). Mice received one intraperitoneal injection per day for 60 consecutive days. Treatment with MeHg significantly increased mercury concentrations in all tissues analysed when compared with the control group. The accumulation of mercury in brain and in liver was further increased in animals that received MeHg-Cys complex when compared with the MeHg alone group. However, renal Hg decreased in MeHg-Cys treated mice, when compared with the group treated only with MeHg. In summary, the transport of MeHg-Cys complex was tissue-specific, and we observed an increase in its uptake by liver and brain as well as a decrease in kidney.

In vitro antioxidant activity of Valeriana officinalis against different neurotoxic agents.

Valeriana officinalis L. (Valerian) is widely used as a traditional medicine to improve the quality of sleep. Although V. officinalis have been well documented as promising pharmacological agent; the exact mechanisms by which this plant act is still unknown. Limited literature data have indicated that V. officinalis extracts can exhibit antioxidant properties against iron in hippocampal neurons in vitro. However, there is no data available about the possible antioxidant effect of V. officinalis against other pro-oxidants in brain. In the present study, the protective effect of V. officinalis on lipid peroxidation (LPO) induced by different pro-oxidant agents with neuropathological importance was examined. Ethanolic extract of valerian (0-60 microg/ml) was tested against quinolinic acid (QA); 3-nitropropionic acid; sodium nitroprusside; iron sulfate (FeSO4) and Fe2+/EDTA induced LPO in rat brain homogenates. The effect of V. officinalis in deoxyribose degradation and reactive oxygen species (ROS) production was also investigated. In brain homogenates, V. officinalis inhibited thiobarbituric acid reactive substances induced by all pro-oxidants tested in a concentration dependent manner. Similarly, V. officinalis caused a significant decrease on the LPO in cerebral cortex and in deoxyribose degradation. QA-induced ROS production in cortical slices was also significantly reduced by V. officinalis. Our results suggest that V. officinalis extract was effective in modulating LPO induced by different pro-oxidant agents. These data may imply that V. officinalis extract, functioning as antioxidant agent, can be beneficial for reducing insomnia complications linked to oxidative stress.

Diphenyl diselenide supplementation delays the development of N-nitroso-N-methylurea-induced mammary tumors.

The effect of dietary diphenyl diselenide (1 ppm) on N-nitroso-N-methylurea (NMU)-induced mammary carcinogenesis was examined in female Wistar rats. Beginning at 5 weeks of age, the animals were fed with either control or diphenyl-diselenide-supplied diets until the end of the study (210 days). At 50 days of age, mammary tumor was induced by the administration of three doses of NMU (50 mg/kg body wt, intraperitoneally) once a week for 3 weeks. In experimental trials, latency to tumor onset was extended in rats fed with diet supplemented with diphenyl diselenide (P < 0.05). The incidence and frequency of tumors were significantly small in animals supplemented with diphenyl diselenide. However, the multiplicity of tumors was not altered by dietary diphenyl diselenide. Diphenyl diselenide supplementation also restored superoxide dismutase (SOD) activity and vitamin C levels altered in the NMU group (P < 0.05). Our results suggest that diphenyl diselenide can be considered a chemopreventive agent, even when supplemented at a relatively low concentration.