Kinetic Study of Singlet-Oxygen Quenching and Aroxyl-Radical Scavenging Activities of Vitamin E Homologs and Fatty Acids Present in Vegetable Oils

Abstract

Introduction In recent years, reactive oxygen species ROS have attracted much attention, because various disorders and diseases are induced by the oxidative stress generated by them 1. Singlet oxygen 1 O 2 and lipid peroxyl radical LOO are well-known representative ROS generated in biological systems. 1 O 2 and LOO react with numerous types of biological molecules such as lipids 2 5 , proteins 6 , and DNA 7, 8 , inducing the degradation of biological systems. Carotenoids and vitamin E homologs α-, β-, γ-, and δ-tocopherols-Tocs and-tocotrienols-Toc-3s are widely present in vegetables, fruits, and edible oils 9 14 and may function as antioxidants AOs by quenching 1 O 2 and/

Finding of Remarkable Synergistic Effect on the Aroxyl-Radical-Scavenging Rates (<i>k</i>_s) under the Coexistence of Vitamin E Homologues (or Vegetable Oils) and Ubiquinol-10: Proposal of A New Mechanism to Explain An Increase of <i>k</i>_s Value

“…Toc and Toc-3 radicals react with LH, and show a prooxidant effect reaction 2 . High concentrations of fatty acids i.e., 75.7 85.5 g/100 g oil are contained in the vegetable oils 1 -8 45 . The result obtained in the present study suggests that the prooxidant reaction due to Toc and Toc-3 radicals may be suppressed by the coexistence of UQ 10 H 2 .…”

“…Recently, it was reported that the total concentrations g/100 g oil of nine fatty acids contained in oils 1 -8 are very high and vary from 75.707 g/100 g of rice bran 1 to 85.520 g/100 g of extra virgin olive oil 6 45 . However, the result of the present kinetic study indicates that effect of fatty acids contained in oils 1 -8 on k s Oil UQ 10 H 2 values of vegetable oils 1 -8 seems to be small and negligible.…”

“…Edible vegetable oils are used for cooking in ordinary homes every day. Vegetable oils 1 -8 see Table 2 generally contain high concentrations of unsaturated lipids, and they are exposed to danger of lipid peroxidation 44,45 . Vegetable oils 1 -8 contain different concentrations of vitamin E homologues see supplementary Table S1 46 49 , and the degradation of oils 1 -8 is prevented by the action of these vitamin E homologues.…”

“…In the present study, measurements of k s Oil values were performed for the mixtures of oils 1 -8 and UQ 10 H 2 . Vegetable oils 1 -8 contain high concentrations of fatty acids 75.7 -85.5 g/100 g vegetable oil 45 , which means that it is interesting to understand whether a similar synergistic effect that is, an increase in the k s AOH value is observed for oils 1 -8 containing UQ 10 H 2 .…”