Kinetic study of quenching reactions of singlet oxygen and scavenging reactions of free radicals by alpha-, beta-, gamma- and delta- tocopheramines in ethanol solution and micellar dispersion.

Quenching reactions of singlet oxygen and scavenging reactions of free radicals by alpha-, beta-, gamma- and delta-tocopheramines (Toc-amines) were investigated spectrophotometrically in ethanol and Triton X-100 micellar dispersions. The rate constants of quenching of singlet oxygen (kQ) by alpha-, beta-, gamma- and delta-Toc-amines increased as the total electron donating capacity of the methyl groups at the aromatic ring increased. A plot of logkQ vs. peak oxidation potential (Ep) was found to be linear and the slope was negative. Similar results were obtained for scavenging of a phenoxyl radical (PhO.). The results suggest that charge transfer plays an important role in these reactions. The kQ values were found to be 1.30-2.57 times as large as kQ for alpha-tocopherol (alpha-Toc). Although alpha-Toc has the highest antioxidant activity among natural tocopherols and related phenols, Toc-amines also can serve as antioxidants.