Atividade antioxidante e anticonvulsivante de suco de uva bordô e seu efeito no comportamento de ratos wistar

Abstract

Grape juice has an important economic role in Brazil, mainly in the state of Rio Grande do Sul, a great important producer of grapes and its derivatives. Currently, it can be found organic grape juice, in which the use of pesticides and genetic engineering in grape cultivation are forbidden, and conventional juices obtained from grapes that receive a series of agrochemicals. A remarkable difference observed between the two types of juices is the content of phenolic compounds, which is higher in organic juice. These compounds have significant antioxidant activity, reducing the incidence of several diseases related to oxidative stress, such as neurodegenerative disorders, cancer and atherosclerosis. Epilepsy is a most common neurological disease worldwide and is characterized by spontaneous and recurrent seizures. These crises may increase the concentration of oxigen reactive species, unbalancing the redox metabolism of epileptic patients. Accordingly, the aim of this study was to evaluate the antioxidant, anticonvulsant and behavior activities of organic and conventional purple grape juices treatments in Wistar rats. In addition, it was determined the content of total and major phenolic compounds of each juice. For the study, male Wistar rats (n = 48), 3 months old, were divided into three groups and treated, by gavage, with saline, organic or conventional grape juice for 17 days (time determined by pilot testing). On the 18th day, the animals were evalueted by the open field test and the possible behavior changes (anxiety, locomotor and exploratory activities) are appointed. After that, half the animals in each group received a single dose of the convulsant drug pentylenetetrazole (PTZ) and they were observed for 30 minutes for evaluation of seizure characteristics (the latency to seizure, the tonic-clonic seizure time, the total seizure time, the number of seizure and how many animals reached the fifth stage on Racine’s scale, the most severe type of seizure). It was also evaluated the mortality rate in each group. Then, the animals were euthanized by decapitation according the animal ethics protocols and the brain structures (hippocampus, cerebellum and cerebral cortex), liver and blood were collected to evaluate the redox metabolism (oxidative damage to lipids and proteins, the nitric oxide content, activity of the superoxide dismutase and catalase enzymes and proteins sulfhydryl content). The results showed that treatment with the juices did not change the behavior of rats and it was not able to minimize the PTZ-induced seizures. However, the treatment with conventional juice prevented the death of animals induced by PTZ, whereas with organic juice mortality was reduced to 33%. By the other hand, both juices prevented the oxidative damage to lipids and proteins, as well as increased the of nitric oxide content in the central nervous system (CNS), liver and serum of rats. It was also observed that treatment with the juices prevented depletion of sulfhydryl proteins in all studied tissues. Organic juice was also able to prevent the reduction of the activity of antioxidant superoxide dismutase and catalase enzymes in all tissues. However, the conventional juice do not prevented the decrease in antioxidant enzyme activity induced by PTZ in the CNS of treated rats. Also, organic juice had a higher organic concentration of total phenolic compounds, catechin, epicatechin, anthocyanins, procyanidin B1 and resveratrol than conventional juice, a factor that may have influenced the results obtained in this work. Therefore, the results obtained in this study open possibility to the delopment of new therapeutic strategies for the treatment of epilepsy in order to increase the quality and expectancy life of epileptic individuals, and contribute to increasing the value of grape juice, favoring the wine country.