(p-ClPhSe)2 modulation on carbohydrate and lipid metabolism requires the insulin-like signaling in Caenorhabditis elegans

Organoselenium compounds modulate the metabolism by regulating carbohydrate and lipid syntheses and degradation in the liver, muscle, and adipose tissue. Notably, p-chloro-diphenyl diselenide (p-ClPhSe)2 can directly regulate the activities of enzymes involved in glucose metabolism, suggesting an insulin-like effect in rodents; however, there is still a lack of scientific evidence to confirm this hypothesis. The objective of this study was to investigate (p-ClPhSe)2 effects on glucose and lipid metabolism in Caenorhabditis elegans. The contribution of AGE-1/PI3K, AKT-1, AKT-2, PFK-1, DAF-16, and DAF-2 in the (p-ClPhSe)2 effects were also investigated. Our results demonstrate that (p-ClPhSe)2 acute exposure presented some toxicity to the worms, and therefore, lower concentrations were further used. (p-ClPhSe)2 reduced glucose and triglyceride levels to the baseline levels, after induction with glucose or fructose, in wild-type worms. This effect required proteins involved in the insulin/IGF-1 like signaling, such as the DAF-2, AGE-1, AKT-1 and AKT-2, PFK-1, but also DAF-16, which would be negatively regulated by DAF-2 activation. Moreover, the reduction in glucose and triglyceride levels, caused by (p-ClPhSe)2per se was lost in age-1/daf-16 worms, suggesting that insulin/IGF-1-like signaling in a DAF-2 and AGE-1/DAF-16 dependent-manner in C. elegans are necessary to effects of (p-ClPhSe)2. In conclusion, (p-ClPhSe)2 requires proteins involved in the IIS pathway to modulate carbohydrate and lipid metabolism.

Bougainvillea glabra Choisy bracts extract in free and liposomal forms reduce hyperplasia induced by let-60gain-of-function in Caenorhabditis elegans

In this study, we evaluated the toxicological and antiproliferative effects of B. glabra Choisy bract extract (BGCE) in its free and loaded into liposomes forms administered to C. elegans mutants with let-60 gain-of-function (gf). Our results demonstrated that the concentration up to 75 μg CAE/mL of BGCE was safe for the worms. Notably, we developed BGCE-loaded liposomes to extend the pharmacological window up to 100 μg CAE/mL without toxicity. In addition, the extract and liposomes reduced the number and area of the multivulva formed in let-60 gf mutants. There was also an increase in the apoptotic signaling in the germline cells and increased longevity mediated through DAF-16 nuclear translocation with GST-4 activation in the treated animals. Our findings demonstrated that the BGCE-loaded liposomes possess antitumoral effects due to the activation of the apoptotic signaling and DAF-16 nuclear translocation.

Nanoencapsulated Curcumin: Enhanced Efficacy in Reversing Memory Loss in An Alzheimer Disease Model

Investigating new drugs or formulations that target Alzheimer disease (AD) is critical for advancing therapeutic interventions. Therefore, this study aimed to assess the effectiveness of nanoencapsulated curcumin (NC Curc) in alleviating memory impairment, oxidative stress, and neuroinflammation in a validated AD model. Male Wistar rats were given bilateral intracerebroventricular injections of either saline or streptozotocin (STZ) (3 mg/3 µL/site) to establish the AD model (day 0). On day 22, daily oral administrations of curcumin (6 mg/kg), NC Curc (6 mg/kg), or a vehicle (unloaded NC) were initiated and continued for 14 days. NC Curc significantly reversed memory deficits in object recognition and inhibitory avoidance tests induced by STZ. Both formulations of curcumin attenuated elevated acetylcholinesterase activity caused by STZ. Importantly, NC Curc alone effectively mitigated STZ-induced oxidative stress. Additionally, NC Curc treatment normalized GFAP levels, suggesting a potential reduction in neuroinflammation in STZ-treated rats. Our findings indicate that NC Curc improves memory in an AD rat model, highlighting its enhanced therapeutic effects compared to unencapsulated curcumin. This research significantly contributes to understanding the therapeutic and neurorestorative potential of NC Curc in AD, particularly in reversing pathophysiological changes.

Purple pitanga extract (Eugenia uniflora) attenuates oxidative stress induced by MPTP

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has been widely used due to its specific and reproducible neurotoxic effect on the nigrostriatal system, being considered a convenient model of dopaminergic neurodegeneration to study interventions therapeutics. The purple pitanga (Eugenia uniflora) is a polyphenol-rich fruit with antioxidant and antidepressant properties, among others. Therefore, this study investigated the effect of purple pitanga extract (PPE) on acute early oxidative stress induced by intranasal 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration in rats. Male Wistar rats were pre-treated orally with PPE (1000 mg/kg) or vehicle. After 24 h, MPTP (0.1 mg/10µL/nostril) or vehicle was administered bilaterally into the animal's nostrils, and 6 h later, the olfactory bulb (OB), striatum (ST), and substantia nigra (SN) were collected to evaluate the oxidative stress parameters. Our findings revealed that OB and SN were the most affected areas after 6 h of MPTP infusion; an early increase in reactive oxygen species (ROS) levels was observed, while pretreatment with a single dose of PPE prevented this increment. No differences in thiobarbituric acid reactive species (TBARS) and 3-nitrotyrosine (3-NT) formation were observed, although 4-hydroxy-2-nonenal (4-HNE) levels increased, which is the most toxic form of lipid peroxidation, in the MPTP group. The PPE pretreatment could prevent this increase by increasing the NPSH levels previously decreased by MPTP. Furthermore, PPE prevents the Na+/K + ATPase strongly inhibited by MPTP, showing the neuroprotective capacity of the PPE by inhibiting the MPTP-generated oxidation. Thus, we demonstrated for the first time the antioxidant and neuroprotective effects of PPE against the early MPTP neurotoxicity.

Development and In Vivo Assessment of 4-Phenyltellanyl-7-chloroquinoline-loaded Polymeric Nanocapsules in Alzheimer's Disease Models

Alzheimer's disease (AD) is the most common form of dementia in older people, and available treatments are palliative and produce undesirable side effects. The 4-phenyltellanyl-7-chloroquinoline (TQ) is an organochalcogen compound studied due to its pharmacological properties, particularly its antioxidant potential. However, TQ possesses some drawbacks such as low aqueous solubility and high toxicity, thus warranting the search for tools that improve the safety and effectiveness of new compounds. Here, we developed and investigated the biological effects of TQ-loaded polymeric nanocapsules (NCTQ) in an AD model in transgenic Caenorhabditis elegans expressing human Aβ_1-42 in their body-wall muscles and Swiss mice injected with Aβ_25-35. The NCTQ displayed good physicochemical properties, including nanometer size and maximum encapsulation capacity. The treatment showed low toxicity, reduced Aβ peptide-induced paralysis, and activated an endoplasmic reticulum chaperone in the C. elegans model. The Aβ injection in mice caused memory impairment, which NCTQ mitigated by improving working, long-term, and aversive memory. Additionally, no changes in biochemical markers were evidenced in mice, demonstrating that there was no hepatotoxicity in the tested doses. Altogether, these findings provide insights into the neuroprotective effects of TQ and indicate that NCTQ is a promising candidate for AD treatment.

Neuroprotective effect of Eugenia uniflora against intranasal MPTP-induced memory impairments in rats: The involvement of pro-BDNF/p75NTR pathway

Parkinson's disease is a multisystemic neurodegenerative disorder that includes motor and non-motor symptoms, and common symptoms include memory loss and learning difficulties. Thus, we investigated the neuroprotective potential of a hydroalcoholic extract of Brazilian purple cherry (Eugenia uniflora) (HAE-BC) on memory impairments induced by intranasal 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration in rats and the involvement of hippocampal BDNF/TrkB/p75^NTR pathway in its effects. Adult male Wistar rats were exposed to MPTP (1 mg/nostril) or vehicle. Twenty-four hours later, the HAE-BC treatments began at doses of 300 or 2000 mg/kg/day or vehicle for 14 days. From 7 days after the MPTP induction, the animals were subjected to behavioral tests to evaluate several cognitive paradigms. HAE-BC treatments, at both doses, blocked the MPTP-caused disruption in the social recognition memory, short- and long-term object recognition memories, and working memory. Furthermore, MPTP-induced motor deficit linked to striatal tyrosine hydroxylase levels decreased, which was blocked by HAE-BC. Our findings demonstrated that HAE-BC blocked the MPTP-induced increase in the hippocampal pro-BDNF, TrkB.t1, and p75^NTR levels. The pro-BDNF/p75^NTR interaction negatively regulates synaptic transmission and plasticity, and the neuroprotective effect of HAE-BC was related, at least partly, to the modulation of this hippocampal signaling pathway. Thus, our study reports the first evidence of the potential therapeutic of E. uniflora in a Parkinson's disease model in rodents.

MeHg exposure impairs both the catecholaminergic and cholinergic systems resulting in motor and non-motor behavioral changes in Drosophila melanogaster

Human exposure to the natural environmental contaminant methylmercury (MeHg) has been associated to adverse health effects. Importantly, the mechanisms by which this organomercurial exerts its neurotoxicity have yet to be fully clarified. Therefore, the aim of this study was to evaluate whether exposure to MeHg alters dopamine (DA) and octopamine (OA) levels, acetylcholinesterase (AChE) activity and impacts both motor and non-motor behaviours. We studied the effect of MeHg by feeding 1-2 d old flies (male and females) with 25 and 50 μM MeHg for 4 d and determined effects on survival, motor and non-motor behaviours, oxidative stress, AChE and tyrosine hydroxylase (TH) activities, as well as DA and OA levels. We found that Drosophila melanogaster (D. melanogaster) exposed to MeHg showed a reduction in survival rate, associated with the inhibition of AChE and TH activities in head of flies and decreased DA and OA levels. These changes were accompanied by behavioural alterations, such as locomotor deficit and increased grooming behaviour, in addition to an increase in oxidative stress markers both in head and in body of flies, and an increase in glutathione-S-transferase (GST) activity in head of flies. Collectively, our data support the hypothesis that MeHg neurotoxicity is associated with altered OA and DA levels, AChE inhibition, which may serve, at least in part, as the underpinnings of both motor and non-motor behavioural changes.

Dihydropyrimidinone-derived selenoesters efficacy and safety in an in vivo model of Aβ aggregation

In a previous in vitro study, dihydropyrimidinone-derived selenoesteres demonstrated antioxidant properties, metal chelators and inhibitory acetylcholinesterase (AChE) activity, making these compounds promising candidates for Alzheimer's Disease (AD) treatment. However, these effects have yet to be demonstrated in an in vivo animal model; therefore, this study aimed to evaluate the safety and efficacy of eight selenoester compounds in a Caenorhabditis elegans model using transgenic strains for amyloid-beta peptide (Aβ) aggregation. The L1 stage worms were acutely exposed (30 min) to the compounds at concentrations ranging from 5 to 200 μM and after 48 h the maintenance temperature was increased to 25 ° C for Aβ expression and aggregation. After 48 h, several parameters related to phenotypic manifestations of Aβ toxicity and mechanistic elucidation were analyzed. At the concentrations tested no significant toxicity of the compounds was found. The selenoester compound FA90 significantly reduced the rate of paralyzed worms and increased the number of swimming movements compared to the untreated worms. In addition, FA90 and FA130 improved egg-laying induced by levamisole and positively modulated HSP-6 and HSP-4 expression, thereby increasing reticular and mitochondrial protein folding response in C. elegans, which could attenuate Aβ aggregation in early exposure. Therefore, our initial screening using an alternative model demonstrated that FA90, among the eight selenoesters evaluated, was the most promising compound for AD evaluation screening in more complex animals.

Potential role of a newly AChE reactivator in the depressive-like behavior induced by malathion

AChE inhibition caused by exposure to organophosphate (OP) compounds is strongly related to behavioural disorders such as depression. Malathion is an OP that already has a relationship between its exposure and behavioural changes, although few data still have its effects in a longer exposure protocol. In addition, intoxication therapy is based on the use of atropine-oxime which still has its controversial efficacy depending on the type of compound. For this, (3Z)-5-Chloro-3-(hydroxyimino)indolin-2-one (Cℓ-HIN), a compound that has properties of isatin and oxime in its structure, have shown reactivating properties in the activity of AChE that have been added to antidepressant-like effects in rats exposed to malathion in acute protocol. In this sense, effects of Cℓ-HIN on the depressive-like behaviour and AChE activity were evaluated in a protocol of subchronic exposure to malathion in rats. Male wistar rats were co-treated with Cℓ-HIN [5 mg/kg, p.o.] and/or malathion [1 or 10 mg/kg, i.p] for 20 days. The exposure to both doses of malathion increased immobility time of rats on the forced swimming test (FST). Besides, malathion inhibited the AChE activity in the prefrontal cortex of rats, but any significant difference was observed in the hippocampus. Cℓ-HIN protected against increased immobility time in the FST of those rats exposed to a dose of 1 mg/kg of malathion. Similarly, Cℓ-HIN was able to reactivate AChE activity only in that group exposed to the lowest dose of malathion. Collectively, the results of this study suggest that Cℓ-HIN is an oxime capable of reactivating AChE inhibited and presents na antidepressant-like effect in cases of prolonged exposure to malathion.

Co-nanoencapsulated meloxicam and curcumin improves cognitive impairment induced by amyloid-beta through modulation of cyclooxygenase-2 in mice

Alzheimer’s disease (AD) is a progressive brain disorder and complex mechanisms are involved in the physiopathology of AD. However, there is data suggesting that inflammation plays a role in its development and progression. Indeed, some non-steroidal anti-inflammatory drugs, such as meloxicam, which act by inhibiting cyclooxygenase-2 (COX-2) have been used as neuroprotective agents in different neurodegenerative disease models. The purpose of this study was to investigate the effects of co-nanoencapsulated curcumin and meloxicam in lipid core nanocapsules (LCN) on cognitive impairment induced by amyloid-beta peptide injection in mice. LCN were prepared by the nanoprecipitation method. Male Swiss mice received a single intracerebroventricular injection of amyloid-beta peptide aggregates (fragment 25–35, 3 nmol/3 μL) or vehicle and were subsequently treated with curcumin-loaded LCN (10 mg/kg) or meloxicam-loaded LCN (5 mg/kg) or meloxicam + curcumin-co-loaded LCN (5 and 10 mg/kg, respectively). Treatments were given on alternate days for 12 days (i.e., six doses, once every 48 hours, by intragastric gavage). Our data showed that amyloid-beta peptide infusion caused long-term memory deficits in the inhibitory avoidance and object recognition tests in mice. In the inhibitory avoidance test, both meloxicam and curcumin formulations (oil or co-loaded LCN) improved amyloid-beta-induced memory impairment in mice. However, only meloxicam and curcumin-co-loaded LCN attenuated non-aversive memory impairment in the object recognition test. Moreover, the beneficial effects of meloxicam and curcumin-co-loaded LCN could be explained by the anti-inflammatory properties of these drugs through cortical COX-2 downregulation. Our study suggests that the neuroprotective potential of meloxicam and curcumin co-nanoencapsulation is associated with cortical COX-2 modulation. This study was approved by the Committee on Care and Use of Experimental Animal Resources, the Federal University of Pampa, Brazil (approval No. 02-2015) on April 16, 2015.

A toxicological comparison between two uranium compounds in Artemia salina: Artificial seawater containing CaCO3

Uranium (U) mining is an aquatic environmental concern because most of these harmful compounds are discharged into freshwater, reaching the saline environment as the final destination of this contaminated water. Carbonates are present in ocean waters and are essential for benthic organisms, however they may influence the U-induced toxicity. Thus, the aim of this study was to compare the toxicity of uranium nitrate (UN) and uranium acetate (UA) in Artemia salina (AS), which is one of the leading representatives of the marine biota. The cultures of AS (instar II) maintained in artificial seawater containing CaCO₃ were exposed for 24 h to different concentrations of U compounds. The results showed that AS were more sensitive to UN (LC₅₀ ≈ 15 μM) when compared with UA (LC₅₀ ≈ 245 μM) indicating higher toxicity of this U compound. Calculated U speciation indicated that Ca₂UO₂(CO₃)₃ and (UO₂)2CO₃(OH)₃^- complexes predominated under our experimental conditions. The immobilization/lethality was observed after 9 h of exposure for both U compounds. However, only UN caused a significant decrease (≈40%) in the acetylcholinesterase (AChE) activity when compared with control. In order to observe preliminary toxicity effects, we evaluated oxidative stress parameters, such as catalase (CAT) activity, TBARS formation, radical species (RS) generation and cell membrane injury and/or apoptosis (CMI). In this study, we demonstrate that U compounds caused a significant decrease in CAT activity. Similarly, we also observed that UN increased TBARS levels in AS at concentrations 5 times lower than AU (10 μM and 50 μM, respectively). Furthermore, RS generation and CMI were enhanced only on AS treated with UN. Overall, the effects observed here were remarkably significant in AS exposed to UN when compared with AU. In this study, we showed different profiles of toxicity for both U compounds, contributing significantly to the current and scarce understanding of the aquatic ecotoxicity of this heavy metal.

Cadmium exposure activates NADPH oxidase, renin-angiotensin system and cyclooxygenase 2 pathways in arteries, inducing hypertension and vascular damage

Exposure to high concentrations of cadmium (Cd), widely used in many industries and found in air, food and contaminated water, is not uncommon. Cd damages the cardiovascular system, but the vascular mechanisms involved are not fully understood. This study investigated the mechanisms involved in cardiovascular damage after exposure to high Cd concentrations. Three-month-old male Wistar rats were treated intraperitoneally for 14 days with distilled water (Untreated group) or 1 mg/kg cadmium chloride (Cd group). We investigated the systolic blood pressure (SBP) and vascular reactivity of mesenteric resistance arteries (MRA) and the aorta by analysing contractile and relaxation responses in the absence and presence of the endothelium; we also evaluated pathways involved in vascular tone regulation. Superoxide anion production, COX-2 protein expression and in situ detection of COX-2, AT-1, and NOX-1 were evaluated. Oxidative status, creatinine level and angiotensin-converting enzyme (ACE) activity in plasma were also evaluated. Fourteen-day exposure to a high Cd concentration induced hypertension associated with vascular dysfunction in MRA and the aorta. In both vessels, there was increased participation of cyclooxygenase 2 (COX2), angiotensin II type 1 (AT1) receptor and NOX1. MRA also presented endothelial dysfunction, denoted by impaired acetylcholine-mediated relaxation. All vascular changes were accompanied by increased reactive oxygen species production and COX2, NOX1 and AT1 receptor expression in vascular tissue. Overall, high Cd concentrations induced cardiovascular damage: hypertension, endothelial dysfunction and vascular damage in conductance and resistance arteries, NADPH oxidase, renin-angiotensin system and COX2 pathway activation.

Airborne toluene exposure causes germline apoptosis and neuronal damage that promotes neurobehavioural changes in Caenorhabditis elegans

Toluene is a highly volatile organic solvent present in gasoline. Exposure mainly occurs by absorption via the pulmonary tract and easily reaches the central nervous system, which causes toxic effects. Toluene toxicity has been described but not well established. The present work aimed to evaluate the effects of airborne exposure to toluene, the in vivo model Caenorhabditis elegans was assessed to determine whether nematode could be used to evaluate the effects of exposure to toluene and the possible mechanisms of toxicity of the solvent. Worms at the first or fourth larval stages were exposed to toluene for 48 or 24 h, respectively, in a laboratory-developed vapor chamber at concentrations of 450, 850, 1250 and 1800 ppm. We observed increases in worm mortality and significant developmental delays that occurred in a concentration-dependent manner. An increased incidence of apoptotic events in treated germline cells was shown, which was consistent with observed reductions in reproductive capacity. In addition, toluene promoted significant behavioural changes affecting swimming movements and radial locomotion, which were associated with changes in the fluorescence intensity and morphology of GABAergic and cholinergic neurons. We conclude that toluene exposure was toxic to C. elegans, with effects produced by the induction of apoptosis and neuronal damage.

(3Z)-5-Chloro-3-(Hydroxyimino)indolin-2-one attenuates hyperglycemia, increased hepatic glycogen content and hepatic damage induced by malathion acute exposure in rats

BACKGROUND

Organophosphorus pesticides (OP's) are heavily constituted in agriculture, gardens, home and veterinary and although it is useful, there are concerns about the environment, safety and health of human and animals. In this study, we investigated the effects of a new oxime, (3Z)-5-Chloro-3-(Hydroxyimino)indolin-2-one (OXIME) against the alterations induced by malathion, an OP insecticide, acute exposure on markers of hepatic damage, glucose homeostasis, oxidative stress in rats cholinesterase (ChE) activity in rats.

METHODS

Adult male Wistar rats were divided into four groups: Control; Malathion; OXIME; and Malathion+OXIME. Twelve hours after co-treatment with malathion (250 mg/kg, i.p.) and/or OXIME (50 mg/kg, i.g.), the plasma and liver samples were collected for biochemical analyses.

RESULTS

The OXIME blocked the increase of plasma markers of hepatic function (AST and ALP) and the enzymatic inhibition of catalase and glutathione reductase in the liver of malathion-treated rats. Moreover, the hepatic cholinesterases inhibition induced by malathion acute exposure was suppressed by OXIME treatment. As assessed, a single dose of OXIME lowered the glycemia levels and hepatic glycogen content enhanced by malathion.

CONCLUSIONS

This study suggests promise effects of (3Z)-5-Chloro-3-(Hydroxyimino) indolin-2-one against the hyperglycemia and the hepatic damage induced by malathion acute exposure, as well as its use as a ChE activity reactivator.

Cationic and anionic unloaded polymeric nanocapsules: Toxicological evaluation in rats shows low toxicity

The experimental design aiming at evaluating the performance of drugs nanoencapsulated involves inclusion of a formulation without drug (unloaded). This formulation has sometimes presented per se effect. In this sense, we sought to evaluate the toxicity of unloaded polymeric nanocapsules (NCs) with different surfaces (cationic and anionic) in male Wistar rats in male Wistar rats. The physicochemical characterization of NCs with different surfaces: polysorbate 80 (P80), polyethylene glycol (PEG), eudragit ®RS 100 (EUD) and chitosan (CS) was performed. Rats were treated with unloaded NCs (P80, PEG, EUD and CS surfaces) daily for 14 days per oral route. 24 h of last treatment, animals were euthanized and organs were removed and weighted. After, biochemical determinations were performed. In general, NCs-surfaces did not cause alterations in body weight, weight of organs and histopathological analysis. PEG-surface NCs did not generate hepatotoxicity. In investigation of lipid profile, the surface with P80 changed TC and HDL-C levels. Besides that, all NCs did not alter oxidative stress markers in organs studied (TBARS and Reactive Species) and CS-surface presented antioxidant activity in kidney. This study demonstrated that NCs-surfaces depending on their physicochemical characteristics had low or no toxicity.

Organoselenotriazoles attenuate oxidative damage induced by mitochondrial dysfunction in mev-1 Caenorhabditis elegans mutants

Organic selenium compounds have several pharmacological activities already described, as anti-inflammatory and antitumor activities, which have been attributed to their antioxidant effects. Because they are promising in pharmacology, the synthesis of these compounds has increased significantly. As many new molecules are synthesized the use of a simple model like Caenorhabditis elegans is highly advantageous for initial evaluation of the toxicity and therapeutic potential of these molecules. The objective of this study was to evaluate the toxicity and antioxidant capacity of a series of selenotriazoles compounds in C. elegans. The animals were exposed to the compounds in liquid medium for only 30 min at the first larval stage (L1). The compounds had no toxic effects at the concentrations tested. Treatment with selenotriazoles (10 μM) partially reversed the stress induced by the pesticide paraquat (1 mM). Se-Tz Ia compound partially increased the survival of worms treated with H₂O₂ (0.5 mM). The compounds also increased the longevity of mev-1 mutants, which have a reduced life span by the production of excessive reactive oxygen species (ROS) in the mitochondria caused by a mutation in complex II of the electron transport chain. In addition, the compounds reduced the levels of ROS determined by the fluorescent probe DCF-DA as well as also reduced catalase enzyme activity in these animals. Based on the results found, it is possible to conclude that the compounds have antioxidant activity mainly in oxidative stress condition generated by a mitochondrial dysfunction in C. elegans.

7-Chloro-4-(Phenylselanyl) Quinoline with Memory Enhancer Action in Aging Rats: Modulation of Neuroplasticity, Acetylcholinesterase Activity, and Cholesterol Levels

This study investigated the effect of 7-chloro-4-(phenylselanyl) quinoline (4-PSQ) to restore the cognitive impairment caused by aging in male Wistar rats. Moreover, modulation of neuroplasticity markers, acetylcholinesterase (AChE) activity, and cholesterol levels was performed. Aged rats were intragastrically treated with 4-PSQ (5 mg/kg) for 7 days. Animals were tested in behavioral tasks, and then plasma (to determine cholesterol levels), hippocampus, and cerebral cortex (to determine neural cell adhesion molecule (NCAM) and polysialyltransferase (PST) levels, and AChE activity) were removed. Our findings demonstrated that treatment of aged rats with 4-PSQ restored short-term and long-term memories in the object recognition tests. 4-PSQ treatment did not restore exploratory activity (rearings) but partially restored locomotor activity (crossings) reduced by aging in the open-field test. Moreover, the compound restored the reduction in the NCAM and PST levels, and AChE activity in cerebral structures, as well as the increase in the plasma cholesterol levels, caused by aging in rats. In conclusion, 4-PSQ restored cognitive impairment caused by aging in rats by modulating synaptic plasticity, cholinergic system, and cholesterol levels.

Thimerosal inhibits Drosophila melanogaster tyrosine hydroxylase (DmTyrH) leading to changes in dopamine levels and impaired motor behavior: implications for neurotoxicity

Thimerosal (THIM) is a well-established antifungal and antiseptic agent widely used as a preservative in vaccines.

Neuroprotective Benefits of Aerobic Exercise and Organoselenium Dietary Supplementation in Hippocampus of Old Rats

The progressive decline of neurological functions, such as learning and memory, is an unavoidable consequence of aging. Our previous work suggested that the combination of physical exercise and a diet supplemented with diphenyl diselenide improves age-related memory decline in rats. The present study investigated the effects of physical exercise and a diet supplemented with diphenyl diselenide on the levels of proteins involved in the hippocampal neuroprotection to figure out the mechanisms related to the beneficial effects of this intervention in aged rats. Male Wistar rats (27 months old) were fed daily with standard chow supplemented with 1 ppm of diphenyl diselenide and subjected to swimming training with a workload (1% of body weight, 20 min/day) for 4 weeks. The hippocampus was dissected from the brain and used for the western blot and immunohistochemistry analyses. The results of this study demonstrate that the association of diphenyl diselenide-supplemented diet and swimming exercise increased the levels of proteins involved in neuroprotection and decreased the activation of those related to apoptosis and neuroinflammation in the hippocampus of old rats. This study suggests that physical exercise and a diet supplemented with (PhSe)₂ promoted neuroprotection in the hippocampus of aged rats.

Ilex paraguariensis crude extract acts on protection and reversion from damage induced by t-butyl hydroperoxide in human erythrocytes: a comparative study with isolated caffeic and/or chlorogenic acids

BACKGROUND

Studies comparing the effects of phytochemicals under different regimens of exposure are necessary to give a better indication about their mechanism(s) of protection. Hence, in the present study, we investigated the preventive (pre-incubation), protective (co-incubation) and/or remediative (post-incubation) activity of chlorogenic acid and caffeic acids, in comparison with Ilex paraguariensis crude extract, against t-butyl hydroperoxide (t-BHP)-induced damage to human erythrocytes.

RESULTS

We found that both caffeic and chlorogenic acids were able to prevent and revert the hemolysis associated with t-BHP exposure. By contrast, isolated compounds (alone or in combination) presented no effect on basal and/or t-BHP-induced non-protein thiol (NPSH) oxidation or production of thiobarbituric acid reactive substances (TBBARS). In turn, I. paraguariensis extract was effective to prevent, protect and revert the hemolysis associated with t-BHP exposure. Moreover, I. paraguariensis significantly protects and reverts t-BHP-induced NPSH oxidation and TBARS production.

CONCLUSIONS

We have found that I. paraguariensis extract acts better with respect to the protection and reversion of t-BHP-associated changes, whereas isolated compounds are more active in preventing and reverting t-BHP pro-hemolytic action. Moreover, our data suggest that the pro-hemolytic activity of t-BHP may occur via mechanism(s) other(s) than lipid peroxidation and/or NPSH oxidation. © 2016 Society of Chemical Industry.

Neurotrophic factors in Alzheimer's and Parkinson's diseases: implications for pathogenesis and therapy

Neurotrophic factors comprise essential secreted proteins that have several functions in neural and non-neural tissues, mediating the development, survival and maintenance of peripheral and central nervous system. Therefore, neurotrophic factor issue has been extensively investigated into the context of neurodegenerative diseases. Alzheimer's disease and Parkinson's disease show changes in the regulation of specific neurotrophic factors and their receptors, which appear to be critical for neuronal degeneration. Indeed, neurotrophic factors prevent cell death in degenerative processes and can enhance the growth and function of affected neurons in these disorders. Based on recent reports, this review discusses the main findings related to the neurotrophic factor support – mainly brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor – in the survival, proliferation and maturation of affected neurons in Alzheimer's disease and Parkinson's disease as well as their putative application as new therapeutic approach for these diseases management.

Involvement of BDNF/TrkB signaling in the effect of diphenyl diselenide on motor function in a Parkinson's disease rat model

Parkinson's disease is a progressive neurodegenerative disorder characterized by degeneration of nigrostriatal dopaminergic neurons. Diphenyl diselenide [(PhSe)₂] is a compound with pharmacological proprieties, such as antidepressant and neuroprotective. Therefore, this study investigated whether (PhSe)₂ reverses motor impairment and neurochemical alterations in a model of Parkinson's disease induced by 6-hydroxydopamine (6-OHDA) in rats. For this, male Wistar rats received 20μg/3μl of 6-OHDA or vehicle into the right striatum. Three weeks later, animals were subjected to rotational behavioral test induced by D-amphetamine and randomly divided into four groups: Sham; (PhSe)₂; 6-OHDA and 6-OHDA+(PhSe)₂. The rats received (PhSe)₂ (1mg/kg/day; i.g.) or vehicle (canola oil) during 30 days. After treatment, behavioral tests were performed in order to evaluate the motor function and the ipsilateral striatal tissue was collected for immunoblotting assay. (PhSe)₂ treatment restored the normal motor behavior of 6-OHDA-infused rats in the cylinder, stepping and bridge tests, but not in the rotarod test. The 6-OHDA infusion and/or (PhSe)₂ treatment did not alter the muscle strength and spontaneous locomotion in the forelimb support and open-field tests, respectively. Additionally, striatal brain-derived neurotrophic factor (BDNF), proBDNF and tyrosine hydroxylase (TH) levels of 6-OHDA-lesioned rats were decreased, while the tropomyosin-related kinase B (TrkB) levels were increased. (PhSe)₂ treatment restored striatal proBDNF, TrkB and TH levels. Thus, (PhSe)₂ treatment reversed some motor impairment and TH levels in a 6-OHDA model of Parkinson's disease in rats, demonstrating a potential neurorestorative role. Additionally, the BDNF/TrkB signaling recovery can be involved in its neurorestorative effect.

The hypolipidemic action of a diet supplemented with p,p'-methoxyl-diphenyl diselenide is not directly related to its antioxidant property

The present study investigated whether a p,p'-methoxyl-diphenyl diselenide (MeOPhSe)2-supplemented diet causes toxicity in rats. A second aim of this study was to determine whether a 10 ppm (MeOPhSe)2-supplemented diet has hypolipidemic effect on Triton WR-1339-induced hyperlipidemia in rats. To rule out the antioxidant property of (MeOPhSe)2 in its hypolipidemic action, parameters of oxidative stress were carried out. Wistar rats were fed with 3, 10, or 30 ppm of (MeOPhSe)2-supplemented diet for 30 days. None of (MeOPhSe)2-supplemented diets caused alteration in general parameters of toxicity and lipid profile of rats. The hypolipidemic effect of 10 ppm of (MeOPhSe)2-supplemented diet on rats treated with Triton WR-1339 (400 mg/kg, intraperitoneal) was investigated. The (MeOPhSe)2-supplemented diet partially protected against the levels of total cholesterol (TC) and non-HDL-C and reduced the atherogenic index (AI) increased by Triton WR-1339 in rats. A positive correlation between TC and triglyceride levels (r = 0.679) and non-HDL-C levels (r = 0.929) and AI (r = 0.889) was demonstrated. Triton WR-1339 altered parameters of oxidative stress in livers of rats but (MeOPhSe)2-supplemented diet did not protect against these alterations. The results demonstrated that the hypolipidemic action of (MeOPhSe)2-supplemented diet is not directly related to its antioxidant property and devoid of systemic toxicity in rats at the parameters analyzed.

p,p'-Methoxyl-diphenyl diselenide prevents neurodegeneration and glial cell activation induced by streptozotocin in rats

The purpose of this study was to investigate possible molecular targets involved in the neuroprotective effect of p,p'-methoxyl-diphenyl diselenide [(MeOPhSe)2], using a streptozotocin (STZ)-induced sporadic dementia of Alzheimer's type rat model. Male Wistar rats were injected with STZ (1.0 mg/8 μl; 4 μl/ventricle). After 21 days of STZ injection, regular diet-fed rats were supplemented with 10 ppm of (MeOPhSe)2 during 30 days. At the end of this period, rats performed object recognition and step-down passive avoidance tasks. Apoptosis was assessed by TUNEL staining and active caspase-3. Glial fibrillary acidic protein, ionized calcium binding adaptor molecule 1, and microtubule associated protein 2 were determined by immunofluorescence in rat hippocampus. The results demonstrate that the (MeOPhSe)2 dietary supplementation reversed STZ-induced memory impairment by enhancing memory in sham rats. (MeOPhSe)2 was also effective in reducing STZ-induced apoptosis and preserving dendrites and synapses. Moreover, (MeOPhSe)2 inhibited activation of microglia and astrogliosis induced by STZ in the rat hippocampus. We conclude that the (MeOPhSe)2 neuroprotective action is related to inhibition of apoptosis and suppression of inflammation.

Diphenyl diselenide reduces mechanical and thermal nociceptive behavioral responses after unilateral intrastriatal administration of 6-hydroxydopamine in rats

Parkinson's disease (PD) patients, in addition to motor dysfunction, also present alterations in pain sensation. The present study characterized the antinociceptive effects of diphenyl diselenide ((PhSe)2) in a model of nociception induced by unilateral, intrastriatal 6-hydroxydopamine (6-OHDA) injection in rats. Male adult Wistar rats received 20 μg/3 μl of 6-OHDA (in saline solution containing 0.02 % of ascorbic acid) or 3 μl of vehicle into the right striatum (1.0 mm anterior, 3.0 mm lateral, and 5.0 mm ventral-with respect to the bregma). Thirty days after injection, rats received (PhSe)2 intragastrically at a dose of 10 mg/kg 1 h before behavioral tests (von Frey hairs, hot plate, tail immersion, formalin, and open field). Our results demonstrated that 6-OHDA injection to rats augmented the response frequency of von Frey hairs (VHF) stimulation, besides reducing the thermal withdrawal latency in the hot plate test. Importantly, the (PhSe)2 treatment decreased the mechanical allodynia measured by the response frequency of VHF stimulation and diminished the thermal nociception in the hot plate test in 6-OHDA-injected rats. In conclusion, these results revealed that a single oral administration of (PhSe)2 1 h prior to the accomplishment of the behavioral tests was effective to attenuate the increased mechanical and thermal nociception caused by a single intrastriatal 6-OHDA injection to rats. Furthermore, other clarifying studies are warranted to improve the evidence bases for future clinical use of (PhSe)2 as a new alternative therapy for the treatment of painful symptoms associated to PD.

Association between oxidative stress and contextual fear conditioning in Carioca high- and low-conditioned freezing rats

We recently reported two novel breeding lines of rats known as Carioca high-and low-conditioned freezing (CHF and CLF), based on defensive freezing responses to contextual cues previously associated with electric footshock. The anxiety-like profile of these animals from the 7th generation was tested in the elevated plus maze. The results indicated that CHF animals presented a significantly more "anxious" phenotype compared with CLF animals. Animals from the 12th generation were used to evaluate the oxidative stress status of the cortex, hippocampus, and cerebellum. Reactive oxidative species (ROS) were evaluated using 2,7-dichlorofluorescin diacetate (DCFH-DA; a sensor of reactive oxygen species [ROS]), and the levels of malondialdehyde (MDA), an early marker of lipid peroxidation, were assessed. The results indicated that free radical concentrations and MDA levels were significantly higher in all three brain structures in CHF rats compared with CLF rats. Our data also showed that the hippocampus had the highest reactive species and MDA concentrations compared with the cortex and cerebellum in CHF rats. Animals from the 16th generation were used to evaluate the antioxidant enzyme activity of catalase (CAT) and glutathione peroxidase (GPx) within these three brain structures. The results indicated that CAT activity was lower in the cortex and hippocampus in CHF rats compared with CLF rats. No significant difference was observed in the cerebellum. The enzymatic activity of GPx was significantly decreased in all three structures in CHF rats compared with CLF rats. The hippocampus exhibited the highest GPx activity compared with the other two brain structures. These findings suggest the involvement of a redox system in these two bidirectional lines, and the hippocampus might be one of the prime brain structures involved in this state of oxidative stress imbalance.

Diphenyl diselenide ameliorates behavioral and oxidative parameters in an animal model of mania induced by ouabain

Bipolar disorder (BD) is a common and severe mood disorder associated with higher rates of suicide and disability. Ouabain, a Na(+)/K(+)-ATPase inhibitor, induces behavioral changes in rats and has been used as a model of mania. The aim of this study was to investigate if diphenyl diselenide [(PhSe)(2)], an organoselenium compound with pharmacological properties, is effective against ouabain-induced hyperactivity and alterations in cerebral oxidative status of rats. Male Wistar rats were treated with a single dose of (PhSe)(2) (50 mg/kg, p.o.) 30 min before i.c.v. injection of ouabain (5 μl, 10(-5) M) or with the mood stabilizer, lithium chloride (LiCl) (45 mg/kg, p.o.), twice a day, for 7 days before the administration of ouabain. Open-field locomotion was quantified after ouabain administration. Thiobarbituric acid reactive substances (TBARS), oxidatively modified proteins, tyrosine nitration, ascorbic acid and non-protein thiols (NPSH) levels and superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR) activities were determined in the whole brain. Ouabain increased locomotor activity in the open-field test and pretreatment with (PhSe)(2) or LiCl blocked this effect. In addition, ouabain increased lipid peroxidation and oxidatively modified proteins, demonstrated by a significant increase in TBARS levels and carbonyl content, which were attenuated by pretreatment with (PhSe)(2) or LiCl. The activities of SOD and CAT were increased by ouabain. LiCl was effective on preventing the increases of both enzyme activities, but (PhSe)(2) attenuated the ouabain effect in SOD activity. GPx and GR activities, ascorbic acid, NPSH and tyrosine nitration levels were not altered in all experimental groups. Similarly to LiCl, (PhSe)(2) produced an antimanic-like action, since it was effective against the locomotor hyperactivity elicited by ouabain. The results also indicated that (PhSe)(2) was effective against oxidative stress caused by ouabain in rats.

Repeated malathion exposure induces behavioral impairment and AChE activity inhibition in brains of rat pups

The present study evaluated if repeated malathion administration would cause behavioral impairment in rat pups. Na+K+ ATPase and acetylcholinesterase (AChE) activities were investigated in brains of rat pups. Malathion was administered (100 or 200 mg/kg) orally (p.o.), once a day for four consecutive days. Rat pups were submitted to behavioral tests on the 5th day, 24 h after the last malathion administration. Malathion at the dose of 200 mg/kg caused a significant increase in the negative geotaxis latency and a decrease in the rotarod latency of rat pups. Rat pups exposed to malathion at both doses showed a significant decrease in the forelimb support latency and an inhibition of brain AChE activity. Repeated exposure of rat pups to malathion caused a decrease in motor coordination, vestibular function and muscular strength/coordination. The brain activity of AChE is involved in the behavioral alterations caused by malathion in rat pups.

Protective effect of brown Brazilian propolis against acute vaginal lesions caused by herpes simplex virus type 2 in mice: involvement of antioxidant and anti-inflammatory mechanisms

Propolis has been highlighted for its antioxidant, anti-inflammatory and antiviral properties. The purpose of this study was to investigate if brown Brazilian hydroalcoholic propolis extract (HPE) protects against vaginal lesions caused by herpes simplex virus type 2 (HSV-2) in female BALB/c mice. The treatment was divided in 5 days of pre-treatment with HPE [50 mg · kg(-1), once a day, intragastric (i.g.)], HSV-2 infection [10 µl of a solution 1 × 10(2) plaque-forming unit (PFU · ml(-1) HSV-2), intravaginal inoculation at day 6] and post-treatment with HPE (50 mg · kg(-1)) for 5 days more. At day 11, the animals were killed, and the in vivo analysis (score of lesions) and ex vivo analysis [haematological and histological evaluation; superoxide dismutase (SOD), catalase (CAT) and myeloperoxidase (MPO) activities; reactive species (RS), tyrosine nitration levels, non-protein thiols (NPSH) and ascorbic acid (AA) levels] were carried out. HPE treatment reduced extravaginal lesions and the histological damage caused by HSV-2 infection in vaginal tissues of animals. HPE was able to decrease RS, tyrosine nitration, AA levels and MPO activity. Also, it protected against the inhibition of CAT activity in vaginal tissues of mice. HPE promoted protective effect on HSV-2 infected animals by acting on inflammatory and oxidative processes, and this effect probably is caused by its antioxidant and anti-inflammatory properties.

Effects of diphenyl diselenide on lipid profile and hepatic oxidative stress parameters in ovariectomized female rats

Objectives

Ovarian hormone decline after menopause is linked to many pathophysiological reactions. Female rats submitted to ovariectomy are employed as a model of post-menopausal condition. This study investigated the effects of diphenyl diselenide (PhSe)2 on body weight gain, intra-abdominal fat deposition, plasma lipid profile and hepatic oxidative stress in ovariectomized rats.

Methods

Female adult Wistar rats were ovariectomized (OVX rats) or sham-operated and divided into four groups: (i) sham-operated, (ii) (PhSe)2, (iii) OVX and (iv) OVX + (PhSe)2. (PhSe)2 (5 mg/kg; 5 ml/kg, p.o.) was administered once a day for 30 days to groups (ii) and (iv). After that, rats were anaesthetized for blood sample gathering and submitted to euthanasia.

Key findings

(PhSe)2 (5 mg/kg) was effective in preventing the rise in body weight gain and intra-abdominal fat deposition induced in OVX rats. Although (PhSe)2 was not effective in avoiding the increase in plasma total cholesterol and non-HDL levels induced in OVX rats, (PhSe)2 reduced plasma triglycerides and augmented HDL levels in OVX rats. (PhSe)2 also increased hepatic ascorbic acid levels, reduced glutathione content, glutathione S-transferase activity and restored catalase activity in liver of OVX rats.

Conclusions

These findings suggest that (PhSe)2 could be a promising alternative to minimize menopause related symptoms.

Acute exposure to diphenyl ditelluride causes oxidative damage in rat lungs

The present study evaluated the effect of acute exposure to diphenyl ditelluride [(PhTe)(2)] on oxidative status in lungs of rats. Rats were exposed to a single subcutaneous application of (PhTe)(2) at the doses of 0.3, 0.6, 0.9 μmol/kg or vehicle. After 72 h of exposure to (PhTe)(2), biochemical parameters of oxidative stress were carried out in lungs of rats. The lungs of rats exposed to (PhTe)(2) showed an increase in the levels of lipid peroxidation, reactive species and non-protein thiol. Alterations in superoxide dismutase activity were observed at all tested doses. (PhTe)(2) caused an increase in catalase activity and a reduction in ascorbic acid levels at the dose of 0.9 μmol/kg. The oxidative damage was more pronounced in animals treated with the highest dose of (PhTe)(2). Thus, this study demonstrated that acute exposure to (PhTe)(2) induced oxidative damage and an adaptive response of antioxidants in pulmonary tissue of rats.

Comparison of the antioxidant properties and the toxicity of p,p'-dichlorodiphenyl ditelluride with the parent compound, diphenyl ditelluride

The hypothesis to be tested in this study is whether the introduction of the chloro group into diphenyl ditelluride molecule (p,p'-dichlorodiphenyl ditelluride, compound 1b) alters the antioxidant and scavenging activity of diphenyl ditelluride (compound 1a) in vitro. The results revealed that 1a and 1b had a potent antioxidant activity in vitro. However, the introduction of a functional group, chloro, into diphenyl ditelluride molecule (1b) did not cause great alterations in the antioxidant action of diphenyl ditelluride against lipid peroxidation, protein carbonyl, and scavenging of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) and 2,2'-diphenyl-1-picrylhydrazyl radicals. Based on the in vitro results, different doses (0.25 and 0.75 µmol/kg) of 1a and 1b or vehicle (canola oil, 1 ml/kg) were administered to rats to investigate if the presence of chloro into diphenyl ditelluride molecule reduces its toxicity. The data demonstrate that the chloro group introduced into diphenyl ditelluride molecule did not alter the acute oral toxicity in rats. The administration of compound 1a in rats only altered the urea level, while compound 1b caused alterations in all toxicological parameters analyzed (alanine aminotransferase and aspartate aminotransferase activities, urea and creatinine levels) in plasma of rats. The results of the present investigation support similar antioxidant and scavenging activities of 1a and 1b in rat liver homogenate in vitro. Furthermore, the presence of chloro into diphenyl ditelluride molecule did not alter the mortality index but increased toxicity of diphenyl ditelluride in rats.

Hydroxyl containing seleno-imine compound exhibits improved anti-oxidant potential and does not inhibit thiol-containing enzymes

Design and synthesis of organoselenium compounds with high thiol peroxidase (TPx) and low thiol oxidase (TOx) activities have been a difficult task and remains a synthetic-activity relationship dilemma. In this regard we are reporting for the first time a detail experimental data (both in vitro and in vivo) about the anti-oxidant and toxicological profile of an Imine (-N) containing organoselenium compound (Compound A). The TPx activity of Compound A was significantly higher than diphenyl diselenide (DPDS). Both Compound A and DPDS protected sodium nitropruside (SNP) induced thiobarbituric acid reactive species (TBARS) production in rats tissue homogenate with significantly higher activity observed for Compound A than DPDS (p<0.05). The Compound A also exhibited strong antioxidant activity in the DPPH and ABTS radical scavenging assays. This study reveals that an imine group close to selenium atom drastically enhances the catalytic activities in the aromatic thiol (PhSH) assay systems. The oxidation of biologically significant thiols reflects the toxicity of the compounds. However, the present data showed that treatment with Compound A at 0, 10, 25 or 50mg/kg was not associated with mortality or body weight loss. Similarly it did not inhibit α-ALA-D and Na(+1)/K(+1) ATPase (sulfhydryl group containing enzymes) activities after acute oral treatment; rather it enhanced non-protein thiols (NPSH) concentration. The Compound A did not cause any oxidative stress as measured by TBARS production in rat's tissue preparation. Our data also indicate that exposure to Compound A did not affect plasma transaminase activities or levels of urea and creatinine in rats. Ascorbic acid is always considered a marker of oxidative stress and the reduction of its content may indicate an increase in oxidative stress. Treatment with Compound A did not alter Ascorbic acid levels in rats. The conducted in vitro and in vivo tests show the versatile therapeutic potential of this compound in the area of free radical induced damages, will undoubtedly enhance our understanding of the mechanism of model compounds and may ultimately yield insights that result in improved GPx mimics.

Involvement of catalase in the protective effect of binaphthyl diselenide against renal damage induced by glycerol

In the present study, the protective effect of binapthyl diselenide [(NapSe)(2)] was investigated on glycerol-induced renal damage in rats. Adult male Wistar rats were treated with (NapSe)(2) (50 mg/kg, orally) or vehicle. After 24 h (NapSe)(2) treatment, the animals received an intramuscular injection of glycerol (8 ml/kg, dissolved in saline) or vehicle as a divided dose into the hind limbs. Twenty-four hours afterwards, rats were euthanized and the levels of urea and creatinine were measured in plasma. Non-protein thiol (NPSH) levels and catalase (CAT) activity were evaluated in renal homogenates. Histopathological evaluations were also performed in kidneys of rats. The rats exposed to glycerol presented swelling of the proximal and distal tubules with evidence of cell damage and death. Glycerol-exposed rats presented an increase in renal failure markers (plasmatic urea and creatinine levels) and a reduction in renal CAT activity. No change was observed in NPSH levels in kidneys of rats exposed to glycerol. (NapSe)(2) protected against the alterations caused by glycerol in rats. (NapSe)(2) increased per se NPSH levels (33%) in kidneys of rats. In conclusion, the results demonstrated that treatment with (NapSe)(2) protected against renal damage induced by glycerol in rats, probably due to its antioxidant effect.