Citral como aditivo na dieta de peixes estuarinos: perfil redox, imunidade inata e parâmetros hepáticos

Abstract

Citral is a monoterpenoid that occurs in essential oils of different plant species used in folk medicine, which also showed promising effects when added to fish diets. However, in spite of the numerous biological activities demonstrated for essential oils, in vivo studies demonstrating the effective benefit of citral are insufficient, especially with regard to the increase of animal production. In Brazil, the growing interest in fish farming and good prospects for growth of commercial fish production increased the search for a healthier diet for the health of these animals. Thus, the objective of this study was to evaluate if the citral added to the diet has beneficial effects on the oxidative profile and innate immunity in juveniles of Centropomus undecimalis (common snook and Mugil liza (mullet). Biochemical markers (alanine aminotransferase and aspartate aminotransferase activity) and liver histology (tissue appearance and lobar center vein morphometry, sinusoidal capillaries and hepatocytes) were determined to evaluate the hepatic toxicity of the tested compound. Citral was commercially obtained and added to the diet of both species for 45 days at different concentrations (0, 0.44, 0.88, 1.76mg kg of diet) giving four experimental groups. Temperature, pH and dissolved oxygen were verified daily, while alkalinity, ammonia and nitrite were measured weekly throughout the experimental period. At the end of the experiment, ten fish from each tank were anesthetized and euthanized by section of the spinal cord to collect blood and tissues. Although in vitro studies have shown that citral has antioxidant capacity and benefical effects with the use of essential oils composed mainly of this monoterpenoid, our results indicate that for common snook the dietary addition of citral does not improve its health conditions. Although the compound under evaluation did not promote hepatic toxicity, it promoted lipoperoxidation in gills and hyperactivation of the complement system. The activity of the enzymes superoxide dismutase, catalase and glutathione-S-transferase increased in response to the oxidative damage evidenced. However, 10 for mullet the incorporation of citral in the diet was beneficial, improving oxidative parameters (reduced lipid peroxidase activity, increased the activity of superoxide dismutase, glutathione peroxidase and glutathione-S-transferase, increased levels of non-protein thiols), without altering the activity of enzymes and histological parameters of the liver. There was a decrease in myeloperoxidase activity in the two species under study. The data presented demonstrated that the physiological differences between the two species have a direct influence on citral activity, which in turn is not indicated as a dietary additive for C. undecimalis, but is recommended to supplement the M. liza diet at the concentration of 1.76 g per kg of diet.