Atividade anticonvulsivante e antioxidante de erva-mate (Ilex paraguariensis, St. Hil.) orgânica e convencional e seu efeito sobre o comportamento de ratos wistar

Abstract

Epilepsy is one of the most common and serious neurological disorders. It is characterized by the occurrence of seizures, which may increase the generation of reactive species, unbalancing the redox metabolism of epileptic patients and increasing the incidence of diseases associated with oxidative stress. Studies have shown that some polyphenols may have anticonvulsant activity in animal models of epilepsy. Yerba mate (Ilex paraguariensis) is a plant rich in polyphenols, compounds with known antioxidant potential. Currently, the cultivation of yerba mate can be made from two different methods, the organic, in which the use of fungicides, inseticides and/or inorganic fertilizers is prohibited, and conventional one, where the use of these inputs are allowed. Studies have shown that some plants grown under organic management have higher polyphenolic content than those produced by conventional cultivation. Thus, the objective of this study was to evaluate the potential anticonvulsant, antioxidant and possible behavioral changes of infusions of yerba mate, organic and conventional in Wistar rats. We also evaluated the polyphenolic profile of both yerba mate samples. Male rats were divided into three groups and treated by oral gavage with distilled water, infusion of organic yerba mate and infusion of conventional yerba mate for 15 days. At the end of treatment, the animals were behaviorally evaluated by the Open Field test. Subsequently, a single dose of the convulsant drug pentylenetetrazole (PTZ) 60 mg/kg (i.p.) was administered and animals were observed for 30 minutes in relation to the latency time, tonic-clonic seizures time, intensity and frequency of seizures, total duration of convulsions and mortality induced by PTZ. Then, the animals were sacrificed and the tissues of the CNS (cerebellum, cerebral cortex and hippocampus), the liver and serum were collected for the evaluation of antioxidant effects of yerba mate infusions. The results showed that both infusions, organic and conventional, did not alter the behavior (locomotor, exploration and anxiety) of the rats. It was observed that treatments with both organic and conventional yerba mate were able to decrease the frequency of seizures in relation to the PTZ group. In adittion, the treatment with organic yerba mate significaltly decreased the time of tonic-clonic seizures when compared to the control group. Both infusions studied showed a tendency of decreasing intensity of seizures (animals that have reached level 5 on the scale of Racine) induced by PTZ. Moreover, infusions of organic and conventional yerba mate reduced the levels of oxidative damage to lipids and proteins, and the levels of nitric oxide raised by PTZ in rats. Both infusions studied prevented, also, the depletion of enzymatic (superoxide dismutase and catalase) and non-enzymatic (protein sulfhydryl content) antioxidant defenses induced by PTZ. There were no differences in total phenolic content between infusions of organic and conventional yerba mate. The phenolic compounds rutin, chlorogenic acid and acyl derivatives, and the alkaloid caffeine were identified in both infusions of yerba mate.