Journal of Lipid Research, Vol. 7, 341-348, May 1966
Copyright © 1966 by Lipid Research, Inc.

Water-soluble products of UV-irradiated, autoxidized linoleic and linolenic acids

Nome Baker and Leon Wilson

Radioisotope Research, Veterans Administration Center, Los Angeles, and Department of Biological Chemistry, UCLA Center for the Health Sciences, Los Angeles, California

The water-soluble products of the UV-initiated autoxidation of linoleic and linolenic acids emulsified in water were separated into volatile and relatively involatile components, each of which reacted with both thiobarbituric acid (TBA) and peroxidase. The volatile TBA-reactive compound is probably malonaldehyde and the volatile peroxidase-reactive compound is hydrogen peroxide. Additional compounds which absorb UV light were present in the volatile fraction.

After thin-layer chromatography of the involatile fraction, reactivity toward TBA and peroxidase was found in the same spot. Approximate molar yields of hydrogen peroxide, malonaldehyde, "hydroperoxides", and other TBA-reactive compounds were estimated. The ratio of "hydroperoxide" to TBA reactivity was lower for linoleic than for linolenic acid.

The mass of relatively involatile compounds was about 20 times greater than that predicted from either peroxidase or TBA assays of water extracts of oxidized linolenic acid. The properties of the water extract were similar to those shown by others for the products of prolonged autoxidation (without UV-irradiation) of emulsified methyl linoleate.

Supplementary key words polyunsaturated fatty acids • autoxidation • water-soluble products • thiobarbituric acid reactivity • hydrogen peroxide • hydroperoxides • metabolic inhibitors • UV-irradiation

Submitted on August 23, 1965
Accepted on December 17, 1965

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