Effect of the essential oil of Lippia alba on oxidative stress parameters in silver catfish (Rhamdia quelen) subjected to transport

Juvenile silver fish (Rhamdia quelen) were exposed to the essential oil of Lippia alba and transported in plastic bags (10 specimens per bag, load density of 140–200 g.L−1) for different periods (5, 6 and 7 h) yielding final different oxygen levels. The biomarkers of oxidative stress, lipoperoxidation (LPO), catalase (CAT), superoxide dismutase (SOD), and glutathione-S-transferase (GST) were measured in the liver, gills and brain of the fish. The juveniles were assigned to 6 different treatment groups according to the presence or not of the essential oil of L. alba in water (10 μL L−1) and the length of transportation, which determined the final concentration of dissolved oxygen inside the bags: Five hours: hyperoxia (13.25 ± 0.35 mg L−1 O2); hyperoxia with L. alba (11.27 ± 0.22 mg L−1 O2); Six hours: normoxia (7.35 ± 0.35 mg L−1 O2); normoxia with L. alba (7.29 ± 0.40 mg L−1 O2); Seven hours: hypoxia (2.29 ± 0.36 mg L−1 O2); hypoxia with L. alba (3.82 ± 0.7 mg L−1 O2). The presence of essential oil of L. alba causes an increase of LPO in the brain of fish transported for 5 h and a decrease of GST in the fish transported for 5 and 7 h as compared to those transported for 6 h. In the liver, this essential oil of L. alba decreased LPO as well the three antioxidants enzymes measured in fish transported for 5 h whilst in the gills there was a decrease of LPO in fish transported for 5 and 7 h. These results suggest that the presence of the essential oil of L. alba improves the redox state in the evaluated tissues, both under hyperoxia and under hypoxia.