Kinetic study of the quenching reaction of singlet oxygen by α-, β-, γ-, δ-tocotrienols, and palm oil and soybean extracts in solution

Abstract

Measurements of the singlet oxygen (1O2) quenching rates (kQ (S)) and the relative singlet oxygen absorption capacity (SOAC) values were performed for 11 antioxidants (AOs) (eight vitamin E homologues (α-, β -, γ-, and δ-tocopherols and -tocotrienols (-Tocs and -Toc-3s)), two vitamin E metabolites (α- and γ-carboxyethyl-6-hydroxychroman), and trolox) in ethanol/chloroform/D2O (50:50:1, v/v/v) and ethanol solutions at 35 ° C. Similar measurements were performed for five palm oil extracts 1- 5 and one soybean extract 6, which included different concentrations of Tocs, Toc-3s, and carotenoids. Furthermore, the concentrations (wt%) of Tocs, Toc-3s, and carotenoids included in extracts 1- 6 were determined. From the results, it has been clari fi ed that the 1O2-quenching rates (kQ (S)) (that is, the relative SOAC value) obtained for extracts 1- 6 may be explained as the sum of the product {Σ kQAO-i (S) [AO- i]/100} of the rate constant (kQAO-i (S)) and the concentration ([AO- i]/100) of AO-i (Tocs, Toc-3s, and carotenoid) included.