Pro‐ and Antioxidative Effect of α‐Tocopherol on Edible Oils, Triglycerides and Fatty Acids

Abstract

Using advanced electron paramagnetic resonance techniques (EPR), oxidation of crude vegetable oils and their components (fatty acids and triglycerides) by radicals generated from hydrogen peroxide was investigated. The correlation rotational times were determined allowing us to characterize radicals formed during edible oils oxidation. Additionally 1H- and 14N-hyperfine coupling constants differentiate the fatty acids dependently on their unsaturation. The acids with a higher number of unsaturated bonds exhibit higher AN values of PBN/·lipid adduct. The waste oil with high free fatty acids content underwent the oxidation reaction more efficiently, however due to saturation and the high content of the fatty acids the carbon-centered radicals formed (upon hydrogen peroxide radicals) and their PBN (N-tert-butyl-α-phenylnitrone) adducts were less stable. The antioxidant effect was dependent on the amount of α-tocopherol added. In small amounts of up to 0.35 mg/1 g of fatty acid or triglyceride, it inhibited the creation of PBN/·lipid adducts while with higher amounts it intensified adduct formation. The α-tocopherol (AT) addition influence was also studied as spin scavenging dependence and indicated that any addition of the antioxidant in the investigated samples led to free radical scavenging and the effect increased with the increase in AT content.

Oxidative stability of the lipid fraction in cookies – the EPR study

“…The obtained EPR parameters for lipid fractions extracted from cookies with added antioxidants (A N = 15.0 G; A H = 1.8-2.1 G, = 0.5-1.4 ns) were in agreement with those previously published for ultrasound-processed sunfl ower oil by Pingret et al [13] (A N = 15 G; A H = 1.85 G), and by Jerzykiewicz et al [19] for oleic acid (A N = 15.0 G; A H = 1.9 G). Such EPR parameters were ascribed to PBN-lipid radical adduct.…”

“…It was probably due to the small amount of oxidation-prone substrates, such as unsaturated lipids, and the increased amount of free fatty acids. As shown by Jerzykiewicz et al [19], the intensity of EPR signal of PBN lipid adducts was signifi cantly lower for free fatty acids than for triglycerides and for saturated fatty acids than for unsaturated ones. In case of cookies with thyme extract, the intensity of obtained EPR spectra of lipid fraction of aged cookies was rather stable and did not depend noticeably on the time of storage of cookies, especially for the lower concentration of thyme extract.…”

Preliminary Study: Comparison of Antioxidant Activity of Cannabidiol (CBD) and α-Tocopherol Added to Refined Olive and Sunflower Oils

“…Studies concerning radicals deriving from lipid oxidation, which are very unstable, are carried out using the spin trap technique and the most used spin trap is n -tert-butyl-α-phenylnitrone (PBN). PBN acts as a trap for temporary radicals and as their scavenger, which is why when there are both antioxidants and PBN in a solution, a competition mechanism occurs and the effect of the interaction among PBN, lipid radicals, and antioxidants depends on the type of oil and antioxidant [21]. The stable radicals produced by PBN spin-trapping are nitroxides with a spectra characterized by three hyperfine lines for the coupling between the electron spin (S = 1/2) and the nitrogen nuclear spin (I = 1) [22].…”

1,2,3‐propanetriol radicals formed during oxidative stress

“…To achieve the objectives unstable radical, product of 1,2,3‐propanetriol oxidation, which was stabilized by creation of paramagnetic spin adducts with PBN (N‐tert‐Butyl‐α‐phenylnitrone), was measured. This experimental method was successful in studies of other not stable radicals formed upon oxidative stress . To complete the spin trapping research of glycerol oxidation products, the theoretical DFT studies were undertaken.…”

“…This experimental method was successful in studies of other not stable radicals formed upon oxidative stress. [9][10][11] To complete the spin trapping research of glycerol oxidation products, the theoretical DFT studies were undertaken. We expected that the comparison of EPR parameters observed for the PBN-glycerol spin adducts with these calculated by DFT for the PBN spin adducts would help to identify the radical formed from 1,2,3-propanetriol.…”