Estudo in vitro do potencial efeito neuroprotetor do chimarrão na toxicidade induzida pelo pesticida clorpirifós

Abstract

The use of pesticides is increasing in Brazil and worldwide. Currently, one of the most used classes of these compounds is the organophosphates. Chlorpyrifos, a widely used organophosphate, is considered one of the most dangerous pesticides for human health due to its ability to cross the blood-brain barrier, making the brain more vulnerable to free radical attacks. Evidence has suggested that exposure to organophosphates is closely related to neuroinflammation, which plays an important role in the pathogenesis of neurodegenerative diseases. Thus, the consumption of foods or substances that have antioxidant and anti-inflammatory activity can be potential alternatives to attenuate the inflammatory process triggered by pesticides and consequently prevent the development of these diseases. Yerba mate (Ilex paraguariensis) is a plant native to South America widely used in the preparation of traditionally consumed beverages such as chimarrão, which is prepared from a partial infusion with hot water, and tererê, prepared from an infusion with ice water. Although the literature reports the anti-inflammatory, antioxidant, anticarcinogenic, antidepressant, anticonvulsant and neuroprotective properties of yerba mate and its extracts, few studies have been carried out mimicking its preparation and consumption conditions. Based on this context, this study aimed to: i) investigate the oxidative and inflammatory response of microglial cell exposure to the chlorpyrifos pesticide; and ii) assess in vitro whether chimarrão could protect or attenuate the neuroinflammatory effects triggered by chlorpyrifos. In the first experimental protocol, the BV-2 microglial cells were exposed to different concentrations of chlorpyrifos (0.3 – 300 μM) for 96 hours. Oxidative stress and the inflammatory response triggered by exposure to this pesticide were evaluated. In the second experimental protocol, a partial infusion was made from yerba mate with hot water, mimicking the condition of preparation and consumption of chimarrão. BV-2 cells were treated with chlorpyrifos, at its inflammatory concentration found from the results of the first experimental protocol, and with chimarrão extract (1 – 100 μg/mL) for 96 hours. The identification and quantification of the bioactive compounds of the chimarrão was carried out through chromatographic analysis. Furthermore, the effect of chimarrão on oxidative stress and the inflammatory response triggered by chlorpyrifos in microglial cells was evaluated. The results of the first article showed that exposure to low concentrations (0.3 – 3 μM) of chlorpyrifos increased cell proliferation and levels of oxidative stress. Furthermore, the pesticide induced the activation of microglial cells and the expression of pro-inflammatory cytokine genes (IL-1β and NLRP3), suggesting that the pesticide chlorpyrifos triggers a neuroinflammatory process. The results of the second manuscript revealed that the main bioactive compounds found in chimarrão are chlorogenic acid, caffeoylquinic acid and caffeine. Furthermore, chimarrão was able to reduce the proliferation and recruitment of BV-2 cells, as well as decrease the production of nitric oxide triggered by the chlorpyrifos and the expression of pro-inflammatory cytokines (IL-1β and TNF-α), and upregulate the expression of the anti-inflammatory cytokine (IL-10). The results suggest that chimarrão could act to attenuate the neuroinflammation process triggered by chlorpyrifos. Therefore, from the experimental results found, it can be concluded that subchronic exposure to low concentrations of chlorpyrifos triggers oxidative-inflammatory responses in immune cells of the central nervous system and that concomitant exposure to chimarrão could attenuate this neuroinflammation process caused by the pesticide.