Pharmacokinetics and metabolism of basil (Ocimum basilicum) essential oil as an anesthetic for tambaqui (Colossoma macropomum).

This study evaluated the pharmacokinetic profile of basil (Ocimum basilicum) essential oil (EO) in juvenile tambaqui (Colossoma macropomum). In trial I, juvenile tambaqui (119.9 ± 9.2 g) were exposed to 800 mg L−1 of EO for 10 min for anesthetic induction. After the blood samples, muscle and brain tissue samples were collected at 2, 4, 6, 8, and 10 min to determine the absorption time and distribution of methyl chavicol and linalool, the major compounds in the EO, the concentration of lactate and ammonia in the muscles, and the plasma levels of lactate, chloride, ammonia, and total calcium. In trial II, anesthetic induction occurred at the same time and concentration and blood, muscle, and brain tissue samples were collected at 0.0, 0.5, 1.0, 3.0, and 6.0 h to quantify the elimination of methyl chavicol and linalool and for a histological evaluation of the gills, liver, and spleen. In assay I, both compounds were identified in the plasma, muscle, and brain as early as 2 min, with maximum concentrations observed within 6 min. In assay II, the half-life of methyl chavicol and linalool in plasma was 0.30 h and 0.46 h, respectively. The half-life of methyl chavicol and linalool in muscle was 1.59 h and 0.32 h, respectively, and the half-life of methyl chavicol and linalool in the brain was 0.69 h and 0.33 h, respectively. The histological lesions observed in the gills between 0 and 3 h were reversible, with organ recovery 6 h after anesthesia induction. There were no changes in the liver and spleen during the times evaluated. The biochemical and pharmacokinetic results in this study confirm that the EO of O. basilicum at 800 mg L−1 is a safe anesthetic for tambaqui, inhibits the stress response, and is eliminated rapidly from the fish. [ABSTRACT FROM AUTHOR]