Petroleum-induced free radical toxicity in African catfish (Clarias gariepinus)

The reaction products derived from lipid peroxidation, as well as superoxide dismutase and catalase enzyme activities were measured in tissues of catfish (Clarias gariepinus) exposed to oil in water dispersions of 0%, 0.5%, 1.0% and 1.5% for 0, 7, 14, 21 and 28 days. Lipid peroxidation significantly (P < 0.05) increased in various tissues relative to control values after 14, 21, and 28 days of exposure to 1.0% and 1.5% oil in water dispersions. Catalase and superoxide dismutase activities decreased after 7 days of exposure but significantly ( P < 0.05) increased after 14, 21 and 28 days of exposure to 1.0% and 1.5% oil in water dispersions. The elevated levels of lipid peroxidation, superoxide dismutase and catalase activities in all tissues examined in C. gariepinus could be a reflection of oxidative stress on the fish. These observations seem to implicate that petroleum hydrocarbons act as a mediator in free radical generation. The increase in catalase and superoxide dismutase activities in these tissues could be an adaptive response to protect the fish from petroleum-hydrocarbon-induced free radical toxicity.