Interactions between lipophilic antioxidants measured by photochemiluminescence assay and α-tocopherol equivalent antioxidant capacity assay as well as the influence of matrix compounds on the lipophilic antioxidant capacity

Abstract

Antioxidant capacity as sum parameter necessarily includes interactions between antioxidants. Thus, two compounds out of α-tocopherol, lycopene, β-carotene and lutein were mixed and measured by lipophilic photochemiluminescence (PCL) assay and α-TEAC assay. In the α-TEAC assay, all mixtures showed an antagonistic effect. The highest antagonistic effect was found for all mixtures of β-carotene and lutein. In contrast, in the PCL system antagonistic, synergistic and additive effects were detected. The mixture β-carotene and lutein 2:1 had the highest synergistic effects. The presence of functional hydroxyl groups and hydrogen bonding effects may have an influence on the interactions. In both assays used, we observed a concentration-dependent effect.The influences of glucose, fructose, saccharose and starch on the antioxidant capacity were determined by PCL and α-TEAC, too. All sugars can have an effect on the lipophilic antioxidant capacity depending on the extraction solvent. The sugar samples, extracted with n-hexane, did not show any antioxidant capacity in α-TEAC assay. In the PCL, the antioxidant potentials of sugars were dependent on the extraction solvent and reflected the dissolubility of sugars in methanol. The better the solubility the higher the antioxidant capacity. Additionally, sugars did not interact with antioxidants, with exception of the methanolic fructose extract.