“Cut-off” effect of antioxidants and/or probes of variable lipophilicity in microheterogeneous media

• Published in: Food chemistry 2016-09, Vol.206, p.119-123
• Main Authors: Aliaga, Carolina, López de Arbina, Amaia, Rezende, Marcos Caroli
• Format: Article
• Language: English
• Subjects: 4-AlkanoyloxyTEMPO; alpha-Tocopherol - chemistry; Antioxidant activity; Antioxidants - chemistry; Ascorbate; Ascorbic Acid - chemistry; BHT; Butylated Hydroxytoluene - chemistry; Chromans - chemistry; EPR; Hydrophobic and Hydrophilic Interactions; Hydrophobicity; Micelle; Micelles; Oxidation-Reduction; Trolox; α-Tocopherol
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2016.03.024

[Display omitted] •Activities of 4 antioxidants in micelle were measured with TEMPO derivatives.•Hydrophilic (ascorbate, Trolox) and hydrophobic (α-tocopherol, BHT) were evaluated.•A “cut-off” effect for C6–C8 chain-length probes was observed for all antioxidants.•C6–C8 were most reactive with hydrophobic and least with hydrophilic antioxidants.•The “cut-off” effect is due to the “amphiphobic” nature of the TEMPO derivatives. The activities of two hydrophilic (ascorbic acid and Trolox) and two hydrophobic (α-tocopherol and BHT) antioxidants were measured by reaction with a series of 4-alkanoyloxyTEMPO radical probes 1 in buffered (pH 7), aqueous, micellar solutions of reduced Triton-X 100. In all cases, a cut-off effect was observed, in line with previous observations of the same effect for the partitioning of probe series 1 in this medium. These results support an interpretation of the cut-off effect in food emulsions, based on the “amphiphobic” nature of either the antioxidants or probes: competition between two molecular moieties, for the micellar hydrophobic core, tends to expose a reacting fragment differently to a more hydrophilic microenvironment, as the probe or antioxidant hydrophobicity increases.