Recent Development in the Field of Antioxidant Action

Abstract

Work from our laboratory showed that free fatty acids decreased the effectiveness of phenolic type antioxidants in unsaturated fats and that phospholipids were effective synergists. We therefore have started to study the effects of other basic substances as model substances, particularly aliphatic amines. Under some conditions, these were very effective synergists for phenolic antioxidants. Dioctylamine and trioctylamine acted as antioxidants themselves in high concentrations. A further study of trioctylamine (TOA) revealed that it was more effective as an antioxidant at 60°C and 70°C that it was at 50°C. Furthermore, with phenolic inhibitors, TOA acted as prooxidant for low levels of phenolic inhibitors and as an antioxidant at higher levels.
These combined observations suggested to us that the antioxidant and synergistic effect of TOA were due to a free-radical intermediate formed by the reaction of TOA with peroxides. TOA was therefore incubated with organic peroxides and with oxidizing fat and the products were examined for antioxidant effectiveness. A crystalline product, m.p. 78°C was isolated. It acted as an antioxidant in unsaturated fat. By elementary analysis and by infra-red absorption spectrum, the product was dioctylhydroxylamine. This pure compound showed evidence of free radical structure by electron-paramagnetic resonance (EPR) analysis. The relationship of this work to the synergistic properties of the phospholipids is now being studied. This work was done by Mrs. L. Harris.