Resveratrol toxicity: Effects on risk factors for atherosclerosis and hepatic oxidative stress in standard and high-fat diets

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Adsorption of MX2 (M = Mn, Ni, Cu, Zn, and Cd; X = Cl, Br, and I) and FeCl3 by modified silica surface with imidazolylpropyl group

Silica gel surface modified with imidazolylpropyl group was used to adsorb MX2 (M = Mn, Ni, Cu, Zn, and Cd; X = Cl, Br, and I) and FeCl3 from ethanol and acetone solution. The adsorption capacity and the intensity of the adsorption were determined by using the Langmuir equation. The influences of the solvent, temperature, and degree of functionalization on the adsorption were also studied. The infrared spectra of the functionalized silica were recorded between 1700-1300 cm-1. The bands of the imidazole skeletal vibrations are shifted to higher frequencies upon metal-to-base nitrogen interaction. © 1985.

Adsorption of Cu(II), Zn(II), Cd(II), Hg(II) and Pb(II) from aqueous solutions on a 2-mercaptobenzimidazole-modified silica gel

The chemically modified silica, obtained by reacting 2-mercaptobenz-imidazole with 3-chloropropyl silica gel, was used to adsorb Cu(II), Zn(II), Cd(II) and Pb(II) from aqueous solutions at various pH. Between pH 3-5, the order of selectivity was Hg(II) > Cd(II) ≫ Cu(II) ∼ Zn(II) ∼ Pb(II). Under batch conditions retentions of 100% were achieved for all metals except for Pb(II) where 93% was attained. Under column conditions recoveries of 100% were obtained for all metals. © 1990 Springer-Verlag.

Influence of the heat treatment in the electrochemical corrosion of Al-Zn-Mg alloys

The localized corrosion of Al-(5.03%)Zn-(1.67%)Mg-(0.23%)Cu alloys and high purity Al has been studied using electrochemical techniques, optical microscopy, SEM and EDX. The samples were previously submitted to different heat treatments in which coherent and incoherent MgZn 2 precipitates with different distribution and aggregation degree were produced. The influence of NaCl and Na 2SO 4, dissolved oxygen, immersion time and convection were studied. In NaCl solutions, pitting potentials for the alloys were more negative than for aluminium, indicating an increase in their susceptibility to localized corrosion. Moreover, annealed and cold-rolled alloys presented more negative pitting and repassivation potentials than those submitted to age hardening with direct or interrupted quenching. In annealed and cold-rolled samples, pit nucleation and propagation takes place in the zones where MgZn 2 is accumulated. In the case of the age-hardened alloys, a double pitting behaviour is observed, the first one in the magnesium and zinc enriched regions and the second in the matrix. While the cold water quenched alloy is susceptible to stress corrosion craking, the alloy submitted to the interrupted quenching process is less susceptible to intergranular attack. The sulphate ion shifts the pitting potential of aluminium and the alloys by chloride towards more positive values because it impedes local accumulations of the latter. © 1992 Chapman & Hall.

Nitrite toxicity in Aspergillus nidulans: Effect of mutation at the nihB gene

The nihB gene of Aspergillus nidulans was found to confer sensitivity to elevated concentrations of nitrite, compact morphology and absence of conidiation. The nihB locus was allocated to linkage group II and was recessive in heterozygous diploids. When the nihB1 mutant was grown on a mixture of nitrite plus NH4 + its sensitivity to nitrite was unchanged. A possible role for this gene in nitrite transport and/or the maintenance of membrane integrity is discussed. © 1992 Rapid Communications of Oxford Ltd.

Protective effect of nickel chloride on superoxide damage: enhancement of CuZn superoxide dismutase affinity to the oxygen free radical.

The effect of nickel from soluble NiCl2 on Cu-Zn superoxide dismutase (SOD) activity, as well as on rate of nitro blue tetrazolium reduction, was studied in vitro since lipid peroxidation has been implicated in cell damage by nickel insoluble compounds, whose toxicity and carcinogenicity are well established. The physical and chemical nature of nickel compounds is one of the key determinations of its toxicity. Soluble nickel freely enter cells, but is just as readily excreted reducing the opportunity for production of lipid damage. Nickel from NiCl2 strongly activated SOD activity. In vitro addition of nickel chloride to a crude lung preparation altered the KM for SOD without changing the Vmax. Nickel chloride produced increased enzyme affinity to the substrate, because decreased (O2-) concentration that yields half-maximal velocity. The combination of nickel and SOD may contribute to stabilization of the particular conformation of SOD responsible for maximal catalytically activity.

Free radical production by azomethine H: Effects on pancreatic and hepatic tissues

The antimalarial properties of azomethine H represent the basis for its use as a chemotherapeutic agent. This work was carried out in order to verify the biological side effects of azomethine H and to clarify the contribution of reactive oxygen species (ROS) in this process. It was shown that azomethine H increased serum activities of amylase, alanine transaminase (ALT) and the TEARS concentrations, in rats. No changes were observed in glutathione peroxidase and catalase activities. The drug-induced tissue damage might be due to superoxide radicals (O-2(.-)), since Cu-Zn superoxide dismutase activities were increased by azomethine I-I treatment. This study allows tentative conclusions to be drawn regarding which reactive oxygen metabolites play a role in azomethine H activity. We concluded that (O-2(.-)) maybe produced as a mediator of azomethine H action.

Superoxide radical and nephrotoxic effect of cadmium exposure

Pollution and industrial practices result in concentrations of metals and other environmental agents that are related to environmental toxicity. Concentrations of metals are widely related to biochemicals values which are used in disease diagnosis due to environmental toxicity. This work was carried out in order to verify the nephrotoxic effect of cadmium and to clarify the contribution of reactive oxygen species (ROS) in this process. Cadmium chloride was tested for nephrotoxic damage in rats by a single intraperitoneal (i.p.) injection Cd 2+ (2 mg/kg) and oral intake (Cd2 +-100 mg/l-from CdCl 2). The cadmium-induced biochemical alterations included significant increased levels of serum creatinine concentrations, in rats with i.p. injection. Total urinary protein concentrations were only increased in rats with cadmium intake. Lipoperoxide was also increased after 3 and 7 days of the Cd 2+ treatment. No changes were observed in glutathione peroxidase activities. Cadmium-induced damage might be due to superoxide radicals (O 2 -), since Cu-Zn superoxide dismutase activities were decreased by Cd 2+ treatment. This study allows tentative conclusions to be drawn regarding which reactive oxygen metabolites play a role in cadmium nephrotoxicity. We concluded that the superoxide radical may be produced as a mediator of nephrotoxic action of cadmium.

Toxicity of synthetic piperonyl compounds to leaf-cutting ants and their symbiotic fungus

The development of Leucoagaricus gongylophorus, the fungus cultured by the leaf-cutting ant Atta sexdens was inhibited in vitro by synthetic compounds containing the piperonyl group. In addition, worker ants that were fed daily on an artificial diet to which these compounds were added had a higher mortality rate than the controls. The inhibition of the fungal growth increased with the size of the carbon side chain ranging from C1 through C8 and decreasing thereafter. 1-(3,4-Methylenedioxybenzyloxy)octane (compound 5) was the most active compound and inhibited the fungal development by 80% at a concentration of 15 μg m1-1. With worker ants the toxic effects started with compound 5 and increased with the number of carbons in the side chain. Thus, for the same concentration (100 μg m1-1) the mortality rates observed after 8 days of diet ingestion were 82%, 66% and 42%, for 1-(3,4-methylenedioxybenzyloxy)decane, 1-(3,4-methylenedioxybenzyloxy)dodecane and compound 5, respectively, whereas with commercial piperonyl butoxide the mortality was 68%. The latter compound, which is known as a synergist insecticide, was as inhibitory to the symbiotic fungus as the synthetic compound 5. The possibility of controlling these insects in the future using compounds that can target simultaneously both organisms is discussed. © 2001 Society of Chemical Industry.

Toxicity of hypercaloric diet and monosodium glutamate: oxidative stress and metabolic shifting in hepatic tissue.

The present study examines the effects of a hypercaloric diet on hepatic glucose metabolism of young rats, with and without monosodium glutamate (MSG) administration, and the association of these treatments with evaluating markers of oxidative stress. Male weaned Wistar rats (21 days old) from mothers fed with a hypercaloric diet or a normal diet, were divided into four groups (n=6): control (C) fed with control diet; (MSG) treated with MSG (4 mg/g) and control diet; (HD) fed with hypercaloric diet and (MSG-HD) treated with MSG and HD. Rats were sacrificed after the oral glucose tolerance test (OGTT), at 45 days of treatments. Serum was used for insulin determination. Glycogen, hexokinase(HK), glucose-6-phosphatase(G6PH), lipid hydroperoxide, superoxide dismutase(SOD) and glutathione peroxidase(GSH-Px) were determined in liver. HD rats showed hypoglycemia, hyperinsulinemia, and high hepatic glycogen, HK and decreased G6PH. MSG and MSG-HD had hyperinsulinemia, hyperglycemia, decreased HK and increased G6PH in hepatic tissue. These animals had impaired OGTT. HD, MSG and MSG-HD groups had increased lipid hydroperoxide and decreased SOD in hepatic tissue. Hypercaloric diet and monosodium glutamate administration induced alterations in metabolic rate of glucose utilization and decreased antioxidant defenses. Therefore, the hepatic glucose metabolic shifting induced by HD intake and MSG administration were associated with oxidative stress in hepatic tissue.

Evaluation of toxicity after one-months treatment with Bauhinia forficata decoction in streptozotocin-induced diabetic rats

Background: Previous experiments have shown that a decoction of Bauhinia forficata leaves reduces the changes in carbohydrate and protein metabolism that occur in rats with streptozotocin-induced diabetes. In the present investigation, the serum activities of enzymes known to be reliable toxicity markers were monitored in normal and streptozotocin-diabetic rats to discover whether the use of B. forficata decoction has toxic effects on liver, muscle or pancreas tissue or on renal microcirculation. Methods: An experimental group of normal and streptozotocin-diabetic rats received an aqueous decoction of fresh B. forficata leaves (150 g/L) by mouth for 33 days while a control group of normal and diabetic rats received water for the same length of time. The serum activity of the toxicity markers lactate dehydrogenase, creatine kinase, amylase, angiotensin-converting enzyme and bilirubin were assayed before receiving B. forficata decoction and on day 19 and 33 of treatment. Results: The toxicity markers in normal and diabetic rats were not altered by the diabetes itself nor by treatment with decoction. Whether or not they received B. forficata decoction the normal rats showed a significant increase in serum amylase activity during the experimental period while there was a tendency for the diabetic rats, both treated and untreated with decoction, to have lower serum amylase activities than the normal rats. Conclusions: Administration of an aqueous decoction of B. forficata is a potential treatment for diabetes and does not produce toxic effects measurable with the enzyme markers used in our study. © 2004 Pepato et al; licensee BioMed Central Ltd.