Effect of 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one on oxidative stress in cerebral cortex of rats

Stability of di-butyl-dichalcogenide-capped gold nanoparticles: experimental data and theoretical insights

Metals capped with organochalcogenides have attracted considerable interest due to their practical applications, which include catalysis, sensing, and biosensing, due to their optical, magnetic, electrochemical, adhesive, lubrication, and antibacterial properties. There are numerous reports of metals capped with organothiol molecules; however, there are few studies on metals capped with organoselenium or organotellurium. Thus, there is a gap to be filled regarding the properties of organochalcogenide systems which can be improved by replacing sulfur with selenium or tellurium. In the last decade, there has been significant development in the synthesis of selenium and tellurium compounds; however, it is difficult to find commercial applications of these compounds because there are few studies showing the feasibility of their synthesis and their advantages compared to organothiol compounds. Stability against oxidation by molecular oxygen under ambient conditions is one of the properties which can be improved by choosing the correct organochalcogenide; this can confer important advantages for many more suitable applications. This paper reports the successful synthesis and characterization of gold nanoparticles functionalized with organochalcogenide molecules (dibutyl-disulfide, dibutyl-diselenide and dibutyl-ditelluride) and evaluates the oxidation stability of the organochalcogenides. Spherical gold nanoparticles with diameters of 24 nm were capped with organochalcogenides and were investigated using X-ray photoelectron spectroscopy (XPS) to show the improved stability of organoselenium compared with organothiol and organotellurium. The results suggest that the organoselenium is a promising candidate to replace organothiol because of its enhanced stability towards oxidation by molecular oxygen under ambient conditions and its slow oxidation rate. The observed difference in the oxidation processes, as discussed, is also in agreement with theoretical calculations.

Evaluation of Oxidative Stress Parameters and Energy Metabolism in Cerebral Cortex of Rats Subjected to Sarcosine Administration

Sarcosine is an N-methyl derivative of the amino acid glycine, and its elevation in tissues and physiological fluids of patients with sarcosinemia could reflect a deficient pool size of activated 1-carbon units. Sarcosinemia is a rare inherited metabolic condition associated with mental retardation. In the present study, we investigated the acute effect of sarcosine and/or creatine plus pyruvate on some parameters of oxidative stress and energy metabolism in cerebral cortex homogenates of 21-day-old Wistar rats. Acute administration of sarcosine induced oxidative stress and diminished the activities of adenylate kinase, GAPDH, complex IV, and mitochondrial and cytosolic creatine kinase. On the other hand, succinate dehydrogenase activity was enhanced in cerebral cortex of rats. Moreover, total sulfhydryl content was significantly diminished, while DCFH oxidation, TBARS content, and activities of SOD and GPx were significantly enhanced by acute administration of sarcosine. Co-administration of creatine plus pyruvate was effective in the prevention of alterations provoked by sarcosine administration on the oxidative stress and the enzymes of phosphoryltransfer network. These results indicate that acute administration of sarcosine may stimulate oxidative stress and alter the energy metabolism in cerebral cortex of rats. In case these effects also occur in humans, they may contribute, along with other mechanisms, to the neurological dysfunction of sarcosinemia, and creatine and pyruvate supplementation could be beneficial to the patients.

Eugenol derivatives as potential anti-oxidants: is phenolic hydroxyl necessary to obtain an effect?

OBJECTIVES

Eugenol, obtained from clove oil (Eugenia caryophyllata), possess several biological activities. It is anti-inflammatory, analgesic, anaesthesic, antipyretic, antiplatelet, anti-anaphylactic, anticonvulsant, anti-oxidant, antibacterial, antidepressant, antifungal and antiviral. The anti-oxidant activity of eugenol have already been proven. From this perspective testing, a series of planned structural derivatives of eugenol were screened to perform structural optimization and consequent increase of the potency of these biological activities.

METHODS

In an attempt to increase structural variability, 16 compounds were synthesized by acylation and alkylation of the phenolic hydroxyl group. Anti-oxidant activity capacity was based on the capture of DPPH radical (2,2-diphenyl-1-picryl-hydrazyl), ABTS radical 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid), measure of TBARS (thiobarbituric acid-reactive species), total sulfhydryl and carbonyl content (eugenol derivatives final concentrations range from 50 to 200 μm).

KEY FINDINGS

Four derivatives presented an efficient concentration to decrease 50% of the DPPH radical (EC50 ) < 100 μm, which has a good potential as a free-radical scavenger. Three of these compounds also showed reduction of ABTS radical. Eugenol derivatives presenting alkyl or aryl (alkylic or arylic) groups substituting hydroxyl 1 of eugenol were effective in reducing lipid peroxidation, protein oxidative damage by carbonyl formation and increase total thiol content in cerebral cortex homogenates. In liver, the eugenol derivatives evaluated had no effect.

CONCLUSIONS

Our results suggest that these molecules are promising anti-oxidants agents.

Kinetic studies on the inhibition of creatine kinase activity by 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one in the cerebral cortex of rats

Tellurium has been used as an industrial component of many alloys and in the electronic industry. Organotellurium compounds can cause poisoning which leads to neurotoxic symptoms such as significant impairment of learning, spatial memory and are potentially neurotoxic to human beings. However, the molecular mechanisms of neurotoxicity of organotellurium compounds are not well understood. Considering that creatine kinase plays a key role in energy metabolism of tissues with intermittently high and fluctuating energy requirements, such as nervous tissue, the main objective of this study was to investigate the mechanisms by which 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one inhibit creatine kinase activity, a key enzyme of energy homeostasis, in the cerebral cortex of 30-day-old Wistar rats. For the kinetic studies, the Lineweaver-Burk plot was used to characterize the mechanisms of enzyme inhibition by 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one. The results suggested that this compound inhibits creatine kinase activity by two different mechanisms: competition with ADP and oxidation of critical sulfhydryl groups for the functioning of the enzyme. The potential for inhibition of creatine kinase to occur in vivo may contribute to the neurotoxicity observed by this organochaocogen.

Effect of chronic administration of the vinyl chalcogenide 3-methyl-1-phenyl-2-(phenylseleno)oct-2-en-1-one on oxidative stress in different brain areas of rats

Selenium (Se) is an essential mineral for mammals. It is a nutrient related to the complex metabolic and enzymatic functions. Although Se has important physiological functions in the cells, organic compounds of Se can be extremely toxic, and may affect the central nervous system. This study aims to investigate the effect of the chronic treatment with the vinyl chalcogenide 3-methyl-1-phenyl-2-(phenylseleno)oct-2-en-1-one on some parameters of oxidative stress in the brain of rats. Animals received the vinyl chalcogenide (125, 250 or 500 μg/kg body weight) intraperitoneally once a day during 30 days. The cerebral cortex, the hippocampus, and the cerebellum were dissected and homogenized in KCl. Afterward, thiobarbituric acid reactive substances (TBARS), carbonyl, sulfhydryl, catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were measured in the brain. Results showed that the organoselenium enhanced TBARS in the cerebral cortex of rats but the compound was not able to change carbonyl levels. Furthermore, the organoselenium reduced thiol groups measured by the sulfhydryl assay in all tissues studied. The activity of the antioxidant enzyme CAT was increased by the organochalcogen in the cerebral cortex and in the cerebellum, and the activity of SOD was increased in the hippocampus. On the other hand, the activity of the antioxidant enzyme GPx was reduced in all brain structures. Our findings indicate that this organoselenium compound induces oxidative stress in different brain regions of rats, corroborating to the fact that this tissue is a potential target for organochalcogen action.

The organochalcogen 3-methyl-1-phenyl-2-(phenylseleno)oct-2-en-1-one induces oxidative stress in heart, liver, and kidney of rats

The objective of this study was to investigate the in vitro effects of the organochalcogen 3-methyl-1-phenyl-2-(phenylseleno)oct-2-en-1-one on some parameters of oxidative stress in liver, kidney, and heart of 10-day-old rats. The homogenates of liver, kidney, and heart were incubated for 1 h in the absence (control) or in the presence of 1, 10, or 30 μM of the organoselenium and thiobarbituric acid reactive substances, carbonyl, and the activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) were measured. First, we tested the influence of the compound on 1,1-diphenyl-2-picrylhydrazyl (DPPH(•)) radical scavenging and verified that the organochalcogen did not have any antioxidant properties. We observed an increase of lipid peroxidation in all concentrations tested in heart and kidney, while in liver only in the concentrations of 10 and 30 μM. Moreover, we also verified an enhance of protein oxidation in the concentrations of 10 and 30 μM in kidney. On the other hand, the compound caused a reduction on the activity of CAT in heart (10 and 30 μM), liver (30 μM), and kidney (30 μM). The activity of SOD was increased in heart (10 and 30 μM), while in liver (30 μM) and in kidney (10 and 30 μM) the activity was reduced. Our findings indicate that this organoselenium compound induces oxidative stress in liver, heart, and kidney of immature rats, collaborating to the fact that these tissues are potential targets for the organochalcogen action.

An in vitro comparison of a new vinyl chalcogenide and sodium selenate on adenosine deaminase activity of human leukocytes

Selenium (Se) is a dietary essential trace element with important biological roles. Sodium selenate (Na(2)SeO(4)) is an inorganic Se compound used in human and animal nutrition that acts as precursor for selenoprotein synthesis. The organoselenium 3-methyl-1-phenyl-2-(phenylseleno)oct-2-en-1-one (C(21)H(2)HOSe) is an α,β-unsaturated ketone functionalized vinyl chalcogenide that has been found as a potential tool in organic synthesis. Adenosine deaminase (ADA) is an important enzyme in the degradation of adenine nucleotides. In this study, we investigated the in vitro effects of both Se compounds on ADA activity and cell viability in leukocyte suspension (LS) of healthy donors (n=12). We first observed an inhibition of ADA activity using 0.1 μM of 3-methyl-1-phenyl-2-(phenylseleno)oct-2-en-1-one, and an increase in cellular viability when 30 μM were used. However, we did not observe alterations in the presence of sodium selenate. Moreover, both Se compounds did not alter lactate dehydrogenase activity and thiobarbituric acid reactive substance levels. These results suggest that the inhibition of ADA activity caused by α,β-unsaturated ketone may affect the adenosine levels in LS and modulate cell viability, attenuating conditions that involve the activation of the immune system.

Effect of acute administration of 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one on oxidative stress in cerebral cortex, hippocampus, and cerebellum of rats

Organotellurium compounds have been synthesized since 1840, but pharmacological and toxicological studies about them are still incipient. Therefore, the objective of this study was to verify the effect of acute administration of the organochalcogen 3-butyl-1-phenyl-2-(phenyltelluro)oct-en-1-one on some parameters of oxidative stress in the brain of 30-day-old rats. Animals were treated intraperitoneally with a single dose of the organotellurium (125, 250, or 500 μg/kg body weight) and sacrificed 60 min after the injection. The cerebral cortex, the hippocampus, and the cerebellum were dissected and homogenized in KCl. Afterward, thiobarbituric acid reactive substances (TBARS), carbonyl, sulfhydryl, catalase (CAT), superoxide dismutase (SOD), nitric oxide (NO) formation, and hydroxyl radical production were measured in the brain. The organotellurium enhanced TBARS in the cerebral cortex and the hippocampus, and increased protein damage (carbonyl) in the cerebral cortex and the cerebellum. In contrast, the compound provoked a reduced loss of thiol groups measured by the sulfhydryl assay in all the tissues studied. Furthermore, the activity of the antioxidant enzyme CAT was reduced by the organochalcogen in the cerebral cortex and the cerebellum, and the activity of SOD was inhibited in all the brain tissues. Moreover, NO production was increased in the cerebral cortex and the cerebellum by this organochalcogen, and hydroxyl radical formation was also enhanced in the cerebral cortex. Our findings indicate that this organotellurium compound induces oxidative stress in the brain of rats, corroborating that this tissue is a potential target for organochalcogen action.

Flavan-3-ol compounds from wine wastes with in vitro and in vivo antioxidant activity

It has been suggested that the dietary intake of antioxidant supplements could be a useful strategy to reduce the incidence of diseases associated with oxidative stress. The aim of present work is to study the possibility to obtain compounds with antioxidant activity from wine wastes using water as solvent. Results have shown that it is possible to obtain flavan-3-ol compounds from wine wastes both from V. vinifera (cv. Cabernet Sauvignon and Merlot) and V. labrusca (cv. Bordo and Isabella) species. The main phenolic compounds found in the extracts were catechin and epicatechin, followed by procyanidin B3, procyanidin B1, procyanidin B2, gallic acid, epigallocatechin, and procyanidin B4. All flavan-3-ol extracts showed significant in vitro and in vivo activities. It was found that the extracts were able to prevent lipid and protein oxidative damage in the cerebral cortex, cerebellum and hippocampus tissues of rats. Although further studies are necessary, these flavan-3-ol extracts show potential to be used to reduce the incidence of degenerative diseases associated with oxidative stress.