Efeito do óleo essencial de Cymbopogon citratus em zebrafish (Danio rerio)

Abstract

Cymbopogon citratus DC. Stapf (Poaceae), is popularly known as lemongrass and several attributes of this plant have been reported. However, the use of its essential oil (EO) in zebrafish (Danio rerio) embryos and larvae is still limited. The objectives of the present study were to evaluate the toxic potential, anti-inflammatory, through caudal fin regeneration, neutrophil recruitment and evaluation of the protective effect of C. citratus EO against oxidative stress, apoptosis and hydrogen peroxide (H2O2)-induced reactive oxygen species in zebrafish. The concentrations analyzed for embryotoxicity assays were 50, 25, 12.5, 6.25, 3.12, 1.56, 0.78 and 0.39 μg/mL, diluted in 0.5% dimethyl sulfoxide (DMSO). Twenty embryos were subjected to their treatment in 96-well plates and analyzed up to 120 hours post-fertilization (hpf). A pool of forty larvae per treatment exposed for up to 96 hpf were used for the analyses of the antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione s-transferase (GST). For the identification of apoptotic cells, 20 72 hpf larvae were used and stained with acridine orange (AO) for 20 minutes. For the other tests, five concentrations (6.25; 3.12; 1.56; 0.78; 0.39 μg/mL) were tested and their effects were analyzed on neutrophil migration, caudal fin regeneration, enzyme activity, apoptosis, and the production of reactive oxygen species (ROS), in zebrafish embryos and larvae exposed to H2O2. The EO showed toxicity at concentrations of 50 and 25 μg/mL at 24 and 72 hpf, respectively. The concentration of 12.5 μg/mL caused 70% mortality. The concentration of 6.25 μg/mL caused teratogenic effects. Compared to control, SOD activity showed a significant reduction at concentrations higher than 0.78 μg/mL, and concentrations higher than 1.56 μg/mL resulted in a significant reduction in CAT activity. There was a significant reduction in neutrophil migration in all EO treatments when compared to the control group. The highest concentrations of EO (3.12 and 6.25 μg/mL) showed a significant reduction in the process of caudal fin regeneration. In addition, a significant reduction of SOD activity was observed in all concentrations of the EO. CAT activity was significantly lower in the 3.12 μg/ml group. On the other hand, GST activity was significantly increased in the 0.78 and 1.56μg/ml groups when compared to the control group. There was no significant difference in ROS production. A reduction in cell apoptosis was observed in all concentrations of OE when compared to the H2O2 control. The results of the studies indicate that the EO of C. citratus at the highest concentrations caused toxic and teratogenic effects in zebra fish embryos and larvae. However, at lower concentration, OE showed no toxicity. In addition, EO has potential for anti-inflammatory effect and protection against free radical formation.