The antioxidant activity of amino acids in two vegetable oils

Abstract

Of 27 amino acids studied, most had some antioxidant activity when added in aqueous solution to either safflower oil or a mixture of sunflower and cottonseed oil (active oxygen and storage methods). Cysteine-HCl, glutamic acid-HC1 (in the mixture), and glutamic acid-HCl (in safflower oil) behaved as prooxidants. When added as a solid, most amino acids were ineffective. The protection factors of these amino acids were less than 1.3 in safflower oil with methionine, proline, lysine and cysteine providing the highest activity. In the oil mixture (which had a higher metal content) lysine, arginine, glutamic acid, methionine, and hydroxyproline were antioxidant with protection factors of up to 1.85. Chelation of metals by amino acids was presumably responsible for the antioxidant activity. The increase in cysteine concentration up to 1% has more than doubled the protection factor in Bint oil (compared with the 0.01% level), whereas with some other amino acids the increase was either small or slight.

Alleviation of Waterlogging Damage in Winter Rape by Uniconazole Application: Effects on Enzyme Activity, Lipid Peroxidation, and Membrane Integrity

“…Furthermore, it has been reported that treatments that increase proline accumulation, such as chilling, increase the tolerance of plants to stress (Flores et al 1988). The prevention of oxidation of unsaturated vegetable oils by proline has also been reported (Ahmad et al 1983). Pretreatment of rape seedlings with uniconazole significantly increased the endogenous free proline content of rape leaves in plants exposed to waterlogging, suggesting the involvement of proline in the protection of rape plants from waterlogging damage.…”

Stabilization of cod liver oil with a quaternary combination of α‐tocopherol and synergists: Method of assessment

“…The effective level of L ‐lysine varies depending on the kinds of assessment used, i.e., the IP or the rate of oxidation products formation. Effective L ‐lysine levels reported in literatures varied 200–10 000 ppm, depending on the kinds of oils substrates, temperature used in the studies and the presence of other additives . The mechanism explaining the synergistic action of L ‐lysine is not well known.…”

Relationship between Proline and Abscisic Acid in the Induction of Chilling Tolerance in Maize Suspension-Cultured Cells

“…It has been shown that plant membrane damage during chilling is related to the peroxidation of membrane lipid due to the stress-induced accumulation of free radicals (Wise and Naylor, 1987). Pro prevents the oxidation of unsaturated vegetable oils (Ahmad et al, 1983). Whether Pro prevents membrane lipid peroxidation in plant tissue by acting as an antioxidant to counteract the chilling-induced free radicals is under investigation.…”