ANTIOXIDANT EFFECTS OF CHLOROPHYLL AND PHEOPHYTIN ON THE AUTOXIDATION OF OILS IN THE DARK .2. THE MECHANISM OF ANTIOXIDATIVE ACTION OF CHLOROPHYLL

To understand the mechanism of the antioxidant effect of chlorophyll on the autoxidation of oils in the dark, antioxidant activities of several derivatives of chlorophyll were compared. Antioxidant activities were observed in chlorophyll derivatives such as protoporphyrin methyl ester and its magnesium chelated compound. Porphyrin seems to be an essential chemical structure for the antioxidant activity of chlorophyll. Chlorophyll did not decompose the hydroperoxides, but reduced free radicals such as 1,1-diphenyl-2-picryl-hydrazyl. Electron spin resonance spectrum of the .pi.-cation radical was recorded during the oxidation of chlorophyll in methyl linoleate solution. These observations suggest that chlorophyll may act as a hydrogen donor to break the chain reaction.