TOXIC EFFECTS OF ETHOXYQUIN ON BIOCHEMICAL AND ENZYMATIC PARAMETERS IN THE FRESHWATER FISH OREOCHROMIS MOSSAMBICUS

Abstract

Ethoxyquin (EQ), a synthetic antioxidant used as a preservative in animal and human foods, prevents oxidative
degradation of fats and fat-soluble vitamins. However, several adverse effects have been reported in animals exposed to EQ,
as it can alter biochemical parameters and antioxidant defense mechanisms, causing organ damage. The present study
evaluated the acute toxicity of EQ in the freshwater fish Oreochromis mossambicus. The median lethal concentration
(LC₅₀ –96 h) determined through bioassay was 11.37 mg/L. Fishes were then exposed to a sublethal concentration (1.14
mg/L) for 24–96 hours, and variations in biochemical and enzymatic parameters were assessed. EQ exposure caused a
consistent decrease in blood total protein and glucose levels, indicating stress and altered glucose metabolism. A timedependent
increase in blood bilirubin suggested impaired bilirubin metabolism. Marker enzymes such as Aspartate
Transaminase (AST), Alanine Transaminase (ALT), Acid Phosphatase (ACP), and Alkaline Phosphatase (ALP) showed
significant elevations in treated groups compared to controls, indicating liver stress, cellular injury, and metabolic
disturbances. These biochemical and enzymatic alterations serve as early warning indicators of EQ-induced toxicity in
aquatic organisms. The findings highlight that even sublethal concentrations of EQ can induce significant physiological
stress in O. mossambicus, emphasizing the potential ecological risks associated with this compound in aquatic environments.