Vitamin C combined with oregano essential oil, Origanum vulgare, reduced oxidative damage in Astyanax aff. bimaculatus exposed to air

We studied the effects of water-soluble (vitamin C, VC) and fat-soluble antioxidants (oregano essential oil, OEO) on the stress responses and redox status of Astyanax aff. bimaculatus exposed to air. Ten isoproteic and isoenergetic diets were formulated, with different levels of VC (0, 40, 80, 120, and 160 mg kg −1 ), with or without OEO (1,000 mg kg −1 ). Fish were fed these diets for 55 days, and then 18 fish from each group were exposed to air. VC at concentrations of 120 and 160 mg kg −1 reduced glycemia. In the gills, VC at 120 and 160 mg kg −1 , only in combination with OEO, reduced oxidative damage (malondialdehyde, MDA, and carbonylated proteins, PC) and superoxide dismutase (SOD) activity. In the absence of VC, OEO increased PC and SOD. In the liver, all VC concentrations, without OEO, reduced MDA while in the presence of OEO, only VC at 40 and 160 mg kg −1 reduced MDA. Regardless of OEO, all VC concentrations reduced PC levels and SOD and catalase (CAT) activity. However, OEO increased CAT and glutathione S-transferase (GST) activity regardless of VC level. While VC at a concentration of 40 with 1,000 mg kg −1 OEO reduced oxidative damage to lipids in the gills and liver, a reduction in protein and lipid damage in the gills was only observed with a least VC 120 + OEO. Therefore, we recommend simultaneous supplementation of VC 120 + 1,000 OEO, as their combined use is more effective in reducing oxidative damage in A. aff. bimaculatus exposed to air.