Profiling of oxidized lipid products of marine fish under acute oxidative stress

Free radical products including reactive oxygen species are potent to oxidize lipids and reliable measurements have been established mostly in human and rodent. To date, robust biomarkers were not used to assess the peroxidation in marine fish. The changes of oxidized lipid products from polyunsaturated fatty acids and cholesterol were assessed after exposure of H2O2 to fish (medaka). Oxidized lipid products released by free radical reaction (F2-isoprostanes and metabolites, F3-isoprostanes, neuroprostanes, 7-ketocholesterol, 7β-hydroxycholesterol), by lipoxygenase enzymes (5(S)-, 8(S)-, 12(S)- and 15(S)-HETE, and resolvin D1) and by cytochrome P450 (9(S)-, 11(S)- and 20-HETE, and 27-hydroxycholestrol) were measured in fish muscle using LC/MS/MS. Arachidonate, docosahexaenoate, eicosapentaenoate and cholesterol levels, and antioxidant enzymes activity (catalase, SOD and gluthathione reductase) measurement were also determined. Activity of antioxidant enzymes especially catalase were elevated in presence of H2O2 however longer exposure time suppressed the antioxidant activities. Arachidonate, docosahexaenoate, eicosapentaenoate and cholesterol levels were reduced in presence of H2O2 and oxidized lipid products (isoprostanes, neuroprostanes 5(S)-HETE, 20-HETE, 7-ketocholesterol, 27-hydroxycholesterol and resolvin D1) were rapidly released in the fish muscle. This study validates oxidized lipid products, noticeably isoprostanes are measurable in marine fish muscle and should be considered when assessing oxidative stress especially due to exogenous factors.