ANTIOXIDANT EFFECT OF RIBOFLAVIN IN ENZYMATIC LIPID-PEROXIDATION

The antioxidant effect, if any, of riboflavin during lipid peroxidation in an enzyme system was studied. When lipoxygenase was added to a mixture of linoleic acid and riboflavin, absorbance at 234 nm increased and absorbance at 444 nm decreased. Starting about 400 s after the addition of lipoxygenase, however, absorbance at 234 nm tended to decrease and that at 444 nm tended to increase. The decrease at 234 nm suggested that hydroperoxide had decomposed, and the increase at 444 nm suggested that the reduced form of riboflavin had been oxidized. When riboflavin is oxidized, the hydroperoxide in it acts as an electron acceptor and the hydroperoxide itself then decomposes. The extent of the phenomenon may be proportional to the amount of the antioxidant.