Denise Bohrer

Diphenyl diselenide, a simple organoselenium compound, decreases methylmercury-induced cerebral, hepatic and renal oxidative stress and mercury deposition in adult mice.

Oxidative stress has been pointed out as an important molecular mechanism in methylmercury (MeHg) intoxication. At low doses, diphenyl diselenide ((PhSe)2), a structurally simple organoselenium compound, has been shown to possess antioxidant and neuroprotective properties. Here we have examined the possible in vivo protective effect of diphenyl diselenide against the potential pro-oxidative effects of MeHg in mouse liver, kidney, cerebrum and cerebellum. The effects of MeHg exposure (2 mg/(kg day) of methylmercury chloride 10 ml/kg, p.o.), as well as the possible antagonist effect of diphenyl diselenide (1 and 0.4 mg/(kg day); s.c.) on body weight gain and on hepatic, cerebellar, cerebral and renal levels of thiobarbituric acid reactive substances (TBARS), non-protein thiols (NPSH), ascorbic acid content, mercury concentrations and activities of antioxidant enzymes (glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD)) were evaluated after 35 days of treatment. MeHg caused an increase in TBARS and decreased NPSH levels in all tissues. MeHg also induced a decrease in hepatic ascorbic acid content and in renal GPx and CAT activities. Diphenyl diselenide (1 mg/kg) conferred protection against MeHg-induced hepatic and renal lipid peroxidation and at both doses prevented the reduction in hepatic NPSH levels. Diphenyl diselenide also conferred a partial protection against MeHg-induced oxidative stress (TBARS and NPSH) in liver and cerebellum. Of particular importance, diphenyl diselenide decreased the deposition of Hg in cerebrum, cerebellum, kidney and liver. The present results indicate that diphenyl diselenide can protect against some toxic effects of MeHg in mice. This protection may be related to its antioxidant properties and its ability to reduce Hg body burden. We posit that formation of a selenol intermediate, which possesses high nucleophilicity and high affinity for MeHg, accounts for the ability of diphenyl diselenide to ameliorate MeHg-induced toxicity.

Presence of synthetic pharmaceuticals as adulterants in slimming phytotherapeutic formulations and their analytical determination

Obesity that is associated with a high consumption of slimming substances is considered a public health problem around the world. In this context, the increasing consumption of phytotherapeutic formulations as alternative obesity treatments has revealed the presence of synthetic pharmaceuticals as adulterants. The illegally added adulterants are frequently anorexic, anxiolytic, and antidepressant pharmaceuticals. This review aims to describe the analytical methodologies utilized for the determination of adulterants in slimming phytotherapeutic formulations. Furthermore, this review describes some important adulteration cases, which occurred mainly in Europe, Asia, Brazil, and the USA.

Cyclooxygenase-2/PGE2 pathway facilitates pentylenetetrazol-induced seizures

Cyclooxygenases (COXs) are rate-limiting enzymes in the metabolic pathways in which arachidonic acid is converted to prostaglandins. COX-2 is the isoform induced at injury/inflammation sites and expressed constitutively in a few tissues, such as the central nervous system, and plays a role in neurodegenerative diseases associated with increased excitatory activity. However, the role of COX-2 and its main product, prostaglandin E(2) (PGE(2)), in the convulsive states is not fully established. In this study we showed that the selective COX-2 inhibitor, celecoxib (at the dose of 2mg/kg, but not at the doses of 0.2 or 20mg/kg, p.o.), protects against the seizures induced by pentylenetetrazol (PTZ, 60 mg/kg, i.p.). The role of PGE(2) in the convulsions induced by PTZ was further investigated by administering anti-PGE(2) antibodies (4 microg/2 microl, i.c.v.), and assessing electroencephalographic changes induced by PTZ (PTZ, 60 mg/kg, i.p.). Anti-PGE(2) antibodies attenuated PTZ-induced seizures in rats. In addition, combining PGE(2) (100 ng/2 microl, i.c.v.) with a subconvulsant dose of PTZ (20mg/kg, i.p.) caused seizures, further supporting a role for this prostaglandin in the convulsions induced by PTZ. Finally, we showed that the anticonvulsant action of celecoxib (2mg/kg, p.o.) was reversed by the intracerebroventricular administration of PGE(2) (10 ng/2 microl, i.c.v.). These data constitute strong converging pharmacological evidence supporting a facilitatory role for the COX-2/PGE(2) pathway in the seizures induced by PTZ. However, whether selective COX-2 inhibitors are safer anti-inflammatory drugs for epileptic patients than nonspecific inhibitors remains to be determined.

Contribution of the raw material to the aluminum contamination in parenterals

BACKGROUND The extent of aluminum contamination in parenteral nutrition solutions was measured in 35 different commercial products, including amino acids, electrolytes, glucose, lipids, vitamins trace elements, and albumin. The extent of aluminum contamination in substances used as raw material for preparation of parenterals was also measured. Chemicals from different manufacturers and of different quality grades were analyzed individually. METHODS The measurements were done by atomic absorption spectrometry. RESULTS The results showed that the same product might have different aluminum content depending on the manufacturer, either for commercial formulations or substances. The highest contaminated chemicals included cystine, NaOH, vitamin C, biotin, gluconate, and Fe and Cr salts. The lowest contaminated chemicals included lipids, apolar amino acids, glucose, HCI, acetic acid, KCl, NaCl, and heparin. Among commercial products, the major contamination rates appeared in calcium gluconate, followed by trace elements, some vitamins, bicarbonate, phosphates salts, and heparin. CONCLUSIONS Comparing the aluminum in commercial products and substances, it can be concluded that the contamination may occur in parenterals because aluminum is present naturally in the chemicals. However, when the composition and concentration of the parenteral solution are considered, the contamination of calcium gluconate, trace elements, some vitamins, phosphates, bicarbonate, and heparin cannot be related only to the raw substances. The aluminum level present in these commercial formulations is too high to come only from the substances; therefore, it is possible that one of the steps of the manufacturing procedure is responsible for elevating the contamination of these products.

Effects of arsenic (As) exposure on the antioxidant status of gills of the zebrafish Danio rerio (Cyprinidae)

In fishes, arsenic (As) is absorbed via the gills and is capable of causing disturbance to the antioxidant system. The objective of present study was to evaluate antioxidant responses after As exposure in gills of zebrafish (Danio rerio, Cyprinidae). Fish were exposed for 48 h to three concentration of As, including the highest As concentration allowed by current Brazilian legislation (10 microg As/L). A control group was exposed to tap water (pH 8.0; 26 degrees C; 7.20 mg O(2)/L). As exposure resulted in (1) an increase (p<0.05) of glutathione (GSH) levels after exposure to 10 and 100 microg As/L, (2) an increase of the glutamate cysteine ligase (GCL) activity in the same concentrations (p<0.05), (3) no significant differences in terms of glutathione reductase, glutathione-S-transferase and catalase activities; (4) a significantly lower (p<0.05) oxygen consumption after exposure to 100 microg As/L; (4) no differences in terms of oxygen reactive species generation and lipid peroxidation content (p>0,05). In the gills, only inorganic As was detected. Overall, it can be concluded that As affected the antioxidant responses increasing GCL activity and GSH levels, even at concentration considered safe by Brazilian legislation.

Influence of the glass packing on the contamination of pharmaceutical products by aluminium. Part III: Interaction container-chemicals during the heating for sterilisation

The interaction of chemicals with the container materials during heating for sterilisation was investigated, storing the components of parenteral nutrition solutions individually in sealed glass ampoules and in contact with a rubber stopper, and heating the system at 121 degrees C for 30 min. Subsequently, the aluminium content of the solutions was measured by atomic absorption spectrometry (AAS). The assay was also carried out with acids, alkalis and some complexing agents for Al. The containers were decomposed and also assayed for aluminium. 30 different commercial solutions for parenteral nutrition, stored either in glass or in plastic containers, were assayed measuring the aluminium present in the solutions and in the container materials. The results of all investigated container materials revealed an aluminium content of 1.57% Al in glass, 0.05% in plastic and 4.54% in rubber. The sterilisation procedure showed that even pure water was able to extract Al from glass and rubber, 22.5 +/- 13.3 microg/L and 79.4 +/- 22.7 microg/L respectively, while from plastic the aluminium leached was insignificant. The Al released from glass ampoules laid between 20 microg/L for leucine, ornithine and lysine solutions and 1500 microg/L for solutions of basic phosphates and bicarbonate; from rubber stoppers it reached levels over 500 microg/L for cysteine, aspartic acid, glutamic acid and cystine solutions. Ion-exchange properties and influence of pH can explain the interaction of glass with some chemicals (salts, acids and alkalis), but only an affinity for aluminium could explain the action of some amino acids and other chemicals, as albumin and heparin, on glass and rubber, considering the aluminium release. Experiments with complexing agents for Al allowed to conclude that the higher the stability constant of the complex, the higher the Al release from the container material.

Effect of aluminum on δ-aminolevulinic acid dehydratase from mouse blood

Abstract The objective of this study was to investigate aluminum deposition in whole blood and plasma of mice and the activity of blood δ-aminolevulinic acid dehydratase (ALA-D) after in vitro and in vivo exposure to this element. In vitro experiments showed activation and inhibition of the enzyme activity when 0.01–5.0 mM of aluminum sulphate were used (IC50: 1.31 mM). Treatment with citrate and aluminum plus citrate increased ALA-D activity in vivo and the increase in enzyme activity was parallel to the increase in aluminum content in blood and plasma. These results show that aluminum has a distinct effect on ALA-D activity: first, at relatively lower concentrations it activated, and at high concentration it inhibited, blood ALA-D in vitro; second, it activated the enzyme when administered to drinking water. One important toxicological finding of the present report is that the apparent irrelevant addition of citrate to the drinking water significantly increased the level of aluminum in blood and plasma. Thus, in order to predict more accurately the extent of human exposure to aluminum it would be advantageous to consider the level of citrate ingestion and not exclusively the aluminum level in water or food.

Effects of aluminum sulfate on delta-aminolevulinate dehydratase from kidney, brain, and liver of adult mice

The purpose of the present study was to investigate the in vitro and in vivo effects of aluminum sulfate on delta-aminolevulinic acid dehydratase (ALA-D) activity from the brain, liver and kidney of adult mice (Swiss albine). In vitro experiments showed that the aluminum sulfate concentration needed to inhibit the enzyme activity was 1.0-5.0 mM (N = 3) in brain, 4.0-5.0 mM (N = 3) in liver and 0.0-5.0 mM (N = 3) in kidney. The in vivo experiments were performed on three groups for one month: 1) control animals (N = 8); 2) animals treated with 1 g% (34 mM) sodium citrate (N = 8) and 3) animals treated with 1 g% (34 mM) sodium citrate plus 3.3 g% (49.5 mM) aluminum sulfate (N = 8). Exposure to aluminum sulfate in drinking water inhibited ALA-D activity in kidney (23.3 +/- 3.7%, mean +/- SEM, P < 0.05 compared to control), but enhanced it in liver (31.2 +/- 15.0%, mean +/- SEM, P < 0.05). The concentrations of aluminum in the brain, liver and kidney of adult mice were determined by graphite furnace atomic absorption spectrometry. The aluminum concentrations increased significantly in the liver (527 +/- 3.9%, mean +/- SEM, P < 0.05) and kidney (283 +/- 1.7%, mean +/- SEM, P < 0.05) but did not change in the brain of aluminum-exposed mice. One of the most important and striking observations was the increase in hepatic aluminum concentration in the mice treated only with 1 g% sodium citrate (34 mM) (217 +/- 1.5%, mean +/- SEM, P < 0.05 compared to control). These results show that aluminum interferes with delta-aminolevulinate dehydratase activity in vitro and in vivo. The accumulation of this element was in the order: liver > kidney > brain. Furthermore, aluminum had only inhibitory properties in vitro, while in vivo it inhibited or stimulated the enzyme depending on the organ studied.

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.

Aluminum-induced oxidative stress in cucumber.

Aluminum (Al) is one of the most abundant elements of the planet and exposure to this metal can cause oxidative stress and lead to various signs of toxicity in plants. Plants are essential organisms for the environment as well as food for humans and animals. The toxic effect of aluminum is the major cause of decreased crop productivity. Thus, the objective of the present study was to analyze the effects of aluminum on the activity of antioxidant enzymes such as catalase (CAT - E.C. 1.11.1.6), superoxide dismutase (SOD - E.C.1.15.1.1) and ascorbate peroxidase (APX - E.C. 1.11.1.11), and on lipid peroxidation, electrolyte leakage percentage (ELP) and chlorophyll and protein oxidation levels in Cucumis sativus L. (cv. Aodai). Seedlings were grown at different concentrations of aluminum ranging from 1 to 2000 microM for 10 days. The increase in ELP and H(2)O(2) production observed in the seedlings may be related to the decreased efficiency of the antioxidant system at higher aluminum concentrations. The antioxidant system was unable to overcome toxicity resulting in negative effects such as lipid peroxidation, protein oxidation and a decrease in the growth of Cucumis seedlings. Aluminum toxicity triggered alterations in the antioxidant and physiological status of growing cucumber seedlings.