Antioxidant Activity of Foods: Development of Singlet Oxygen Absorption Capacity (SOAC) Assay Method

Abstract

Recently a new assay method that can quantify the singlet oxygen absorption capacity (SOAC) of antioxidants (AOs) and food extracts was proposed. Singlet oxygen (1 O2) quenching rates (kQ) and the relative SOAC values were measured for many carotenoids and phenolic AOs in ethanol/chloroform/D2O (50 : 50 : 1, v/v/v) solution at 35˚C using UVvis spectrophotometry. It has been clarified that the SOAC method is useful to evaluate the 1 O2-quenching activity of lipophilic and hydrophilic AOs having 5 orders of magnitude different rate constants (kQ). Measurements of the kQ and SOAC values were also performed for 39 kinds of food extracts. The results indicate that the SOAC method is useful to evaluate the 1 O2-quenching activity of food extracts having two orders of magnitude different kQ values. Further, the kQ values for the reaction of 1 O2 with 8 carotenoids and 8 vitamin E homologues were measured in an aqueous Triton X-100 (5.0 wt %) micellar solution (pH 7.4). Results obtained demonstrate that the kQ values of AOs in homogeneous and heterogeneous solutions vary notably depending on (i) polarity (dielectric constant (e)) of the reaction field between AOs and 1 O2, (ii) local concentration of AOs, and (iii) mobility of AOs in solution. Measurements of kQ and SOAC values in a micellar solution may be useful for evaluating the 1 O2-quenching activity of AOs in biological systems. Furthermore, measurements of the SOAC values were performed for 32 kinds of food extracts using a microplate reader. The SOAC assay method was validated by inter-laboratory validation study due to 14 laboratories.

Factors Differentiating the Antioxidant Activity of Macular Xanthophylls in the Human Eye Retina

“…However, the accumulation of zeaxanthin into cell membranes was shown to be higher than that for lutein [108,109]. Finally, based on the presented materials, we can state that, in terms of its antioxidant properties, zeaxanthin is a better lipid-soluble singlet-oxygen quencher and is less rapidly oxidized by singlet oxygen than lutein [25][26][27][29][30][31]65].…”

“…In the future, an investigation should be done to determine whether zeaxanthin is a more potent lipid antioxidant than lutein. A comparison of the capacity to quench singlet oxygen by zeaxanthin and lutein in organic solutions has been presented in numerous studies [25][26][27][28]. However, the quenching of singlet oxygen by macular xanthophylls in a lipid environment has not been studied intensively [29][30][31].…”

Method to Improve Azo-Compound (AAPH)-Induced Hemolysis of Erythrocytes for Assessing Antioxidant Activity of Lipophilic Compounds

“…However, only a relatively small number of methods have been reported to monitor antioxidant activity of lipophilic compounds. [38][39][40] Therefore, we attempted to identify a condition for applying the method of AAPH-induced oxidative hemolysis for assessing antioxidant activity of lipophilic compounds. Initially, several agents were examined to find appropriate agents for dispersing lipophilic compounds.…”

Prediction and Chemical Interpretation of Singlet-Oxygen-Scavenging Activity of Small Molecule Compounds by Using Machine Learning

“…The singlet-oxygen-scavenging capacities of 74 compounds were used in the dataset. The SOAC values of compounds were obtained from previous studies [ 8 ]. The SOAC values can be calculated as the ratio of the quenching rate constants of the antioxidants and α-tocopherol.…”

“…The singlet-oxygen-scavenging ability is critical for peroxyl radical scavenging [ 7 ]. The singlet oxygen absorbance capacity (SOAC) assay [ 8 ] was developed to measure the singlet oxygen. Research on the effects of foods and compounds on singlet oxygen is ongoing.…”