Effect of autoxidized oil on carp - II. Decomposition of linoleic acid hydroperoxide in carp intestine.

Abstract

To clarify the toxic effect of lipid hydroperoxides on fish, the decomposition process of lipid hydroperoxides in carp intestinal tissue was studied. Pure linoleic acid hydroperoxide was incubated with carp intestinal extract or acetone powder, and the decomposition rate of hydroperoxide and the formation of carbonyl compounds were investigated. To determine the degree of involvement of the enzymatic reaction in the decomposition of hydroperoxides, the data was compared with the control system which was incubated with the boiled intestinal preparation. In addition, the inhibitory effect of EDTA and cyanide was also investigated to examine the influence of metal ions and heme compounds on the reaction. As a result, both the systems decomposed approximately equivalent amount of hydroperoxide and carbonyl compounds, specially unsaturated carbonyls were elevated more in the experimental system than in the control. This result was supported by a higher UV absorption at 275nm of the experimental system. Both EDTA and cyanide have only a partial inhibitory effect on the reaction. These data indicate that most of the lipid hydroperoxides were decomposed in carp intestinal tissue and converted to carbonyl compounds. It was suggested that heat-unstable substances in the carp's intestine were partly involved in the formation of unsaturated carbonyls from lipid peroxides.