AbstractGamma-linolenic acid (GLA 18:3 n-6) is an essential fatty acid which kills several human cancer cell lines at concentrations which do not harm normal cells. The lethal effects of GLA are enhanced by iron and other pro-oxidant compounds while being inhibited by vitamin C and other anti-oxidants. The cell killing is associated with the formation of lipid peroxides as indicated by the formation of thiobarbituric acid reactive substances (TBARS). TBARS are made up of malondialdehyde (MDA) and MDA-related substances which are produced during lipid peroxidation. They represent the end-stages of the reaction sequence. In order to explore further the process of lipid peroxidation in cancer cells in response to GLA we have now used two further techniques. Primary lipid peroxidation products formed at early stages in the reaction have a hydroperoxyl group and a conjugated diene in the molecule which absorbs strongly at approximately 234 nm. Schiff's reaction which involves the reaction of the Schiff reagent with certain aldehydes or carbonyl compounds to produce material which absorbs strongly at 544 nm has also been used to monitor lipid peroxidation in the liver. We have therefore investigated these two additional indicators of lipid peroxidation processes in normal and cancer cells exposed to GLA. Preliminary accounts of this work have been presented previously.
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