Methyl parathion activation by a partially purified rat brain fraction

Influence of agricultural land-use and pesticides on benthic macroinvertebrate assemblages in an agricultural river basin in southeast Brazil

Land-use alterations and pesticide run-offs are among the main causes for impairment in agricultural areas. We evaluated the influence of different land-uses (forest, pasture and intensive agriculture) on the water quality and on benthic macroinvertebrate assemblages on three occasions: in the dry season, wet season and at the end of the wet season. Macroinvertebrates responded to this gradient of impairment: agricultural sites had significantly lower richness numbers than forested and pasture sites, and all major invertebrate groups were significantly affected. Most taxa found in forested sites were found in pasture sites, but often with lower densities. In this case, the loss of habitats due to sedimentation and the lower complexity of substrates seem to be the disruptive force for the macroinvertebrate fauna.

Macro and micro minerals: are frozen fruits a good source?

Fruits are rich in minerals, which are essential for a wide variety of metabolic and physiologic processes in the human body. The use of frozen fruits has greatly spread in the last years not only in the preparation of juices, but also as raw material for yogurts, candies, cookies, cakes, ice creams, and children's food. However, up to now there is no data about the mineral profile of frozen fruits. This is the first database to quantify the levels of minerals in 23 samples of frozen fruits, including the most used around the world and some native fruits from the Amazon rainforest in Brazil. Considering the Dietary Reference Intakes, 100g of frozen fruits can provide 0.2 to 2.8% of macro and 2.5 to 100% of microminerals for adults (31-50 years old). Although geographical differences should be considered, these data can help to plan diets and to develop population interventions aiming to prevent chronic diseases.

Development of a simple and low-cost enzymatic methodology for quantitative analysis of carbamates in meat samples of forensic interest

Foods contaminated with a granulated material similar to Temik (a commercial pesticide formulation containing the carbamate insecticide aldicarb) are often involved in accidental ingestion, suicides, and homicides in Brazil. We developed a simple technique to detect aldicarb. This technique is based on the inhibition of a stable preparation of the enzyme acetylcholinesterase, and it is specially adapted for forensic purposes. It comprises an initial extraction step with the solvent methylene chloride followed by a colorimetric acetylcholinesterase assay. We propose that results of testing contaminated forensic samples be expressed in aldicarb equivalents because, even though all other carbamates are also potent enzyme inhibitors, aldicarb is the contaminant most frequently found in forensic samples. This method is rapid (several samples can be run in a period of 2 h) and low cost. This method also proved to be precise and accurate, detecting concentrations as low as 40 microg/kg of aldicarb in meat samples.

Frozen fruit pulp of Euterpe oleraceae Mart. (Acai) prevents hydrogen peroxide-induced damage in the cerebral cortex, cerebellum, and hippocampus of rats

Oxidative stress is implicated in several human illnesses, including neurological disorders such as Parkinson's and Alzheimer's diseases. Acai is largely consumed in Brazil and contains high levels of antioxidant compounds. This work aims to study the antioxidant activity of acai frozen fruit pulp in the cerebral cortex, hippocampus, and cerebellum of rats treated with the oxidizing agent hydrogen peroxide (H(2)O(2)). Pretreatment of tissue with acai decreased H(2)O(2)-induced damage of both lipids and proteins in all tissues tested. This fruit was also able to reduce the activities of the antioxidant enzymes superoxide dismutase and catalase to basal levels. We observed a negative correlation between the polyphenol content of acai and the levels of lipid (r = -0.689; P <or= .05) and protein damage (r = -0.569; P <or= .05), suggesting the participation of polyphenols in the observed antioxidant activity. These data suggest that acai has a positive contribution in the development of age-related neurodegenerative diseases.

Phenolic content and antioxidant activities of white and purple juices manufactured with organically- or conventionally-produced grapes

Although the beneficial effects of moderate wine intake are well-known, data on antioxidant capacity of grape juices are scarce and controversial. The purpose of this study was to quantify total polyphenols, anthocyanins, resveratrol, catechin, epicatechin, procyanidins, and ascorbic acid contents in grape juices, and to assess their possible antioxidant activity. Eight Vitis labrusca juices--white or purple, from organically- or conventionally-grown grapes, and obtained in pilot or commercial scale--were used. Organic grape juices showed statistically different (p<0.05) higher values of total polyphenols and resveratrol as compared conventional grape juices. Purple juices presented higher total polyphenol content and in vitro antioxidant activity as compared to white juices, and this activity was positively correlated (r=0.680; p<0.01) with total polyphenol content. These results indicate that white and purple grape juices can be used as antioxidants and nutritional sources.

Avaliação integrada do impacto do uso de agrotóxicos sobre a saúde humana em uma comunidade agrícola de Nova Friburgo, RJ

O impacto do uso de agrotóxicos sobre a saúde humana é um problema que tem merecido atenção da comunidade científica em todo o mundo, sobretudo nos países em desenvolvimento. O consumo de agrotóxicos na região sudeste do Brasil está estimado em 12kg de agrotóxico/trabalhador/ano. Em algumas áreas agrícolas do Estado do Rio de Janeiro, como na região da Microbacia do Córrego de São Lourenço, Nova Friburgo, o consumo de agrotóxico foi estimado em 56kg de agrotóxico/trabalhador/ano. Elevados níveis de contaminação humana e ambiental foram encontrados nesta região, como decorrência do uso extensivo destes agentes químicos. A avaliação do impacto sobre a saúde humana implica o conhecimento e a visualização da importância/magnitude relativa de cada uma das vias de contaminação. Inúmeros fatores, que, em geral, encontram-se inter-relacionados, contribuem para a situação encontrada na Microbacia do Córrego de São Lourenço e a forma mais adequada de se avaliar toda a dimensão deste problema é o uso de uma abordagem integrada.

Cytochrome P450 2B (CYP2B)-mediated activation of methyl-parathion in rat brain extracts

The role of cytochrome P450 (CYP) and the CYP isoform involved in the activation of the widely used pesticide methyl-parathion (MePA) were investigated in rat brain extracts by measuring the effect of different CYP inhibitors on acetylcholinesterase (AChE) inhibition by MePA. Brain extracts provide a useful tool to study the activation mechanisms of organophosphorus compounds (OP) since they contain both the activating enzyme(s) and the molecular target for OP toxicity. As expected, in incubations of rat brain extract supplemented with NADPH, AChE activity was non-competitively inhibited by the presence of MePA, indicating that MePA was activated to its reactive metabolite methyl-paraoxon (MePO). Indeed, Vmax(app) decreased from 13.4 to 8.7 micromol thionitrobenzoic acid (TNB)/min per mg protein. MePA activation by rat brain extracts, as measured by the AChE inhibition produced by the presence of the pesticide in the incubation, was fully prevented by previously bubbling the incubation mix with CO, by the presence of monoclonal anti-rat CYP2B1/2B2 antibodies and by the addition of phenobarbital (PB), a CYP2B substrate. Interestingly, MePA showed a greater affinity for CYP2B than PB. CYP1A1 antibodies showed no effect on MePA activation. The presence of cytochrome P450 2B (CYP2B) in the rat brain extracts was confirmed by immunoblotting. These results demonstrate indisputably the responsibility of CYP2B in MePA activation in the rat brain in vitro, suggesting that metabolic activation of OP compounds in situ might be crucial for their organ specific toxicity to the central nervous system also in vivo.