α-tocopherol oxidation mediated by superoxide anion (O ₂ ^- ). II. Identification of the stable α-tocopherol oxidation products

The present paper describes the identification of two stable end products of α-tocopherol oxidation that were previously detected among the products of the reaction of α-tocopherol with superoxide anion (O ₂ ^- ) under aprotic conditions. One compound, previously designated compound A, was identified as trans-7-hydroxy-trans-8,8a-epoxy-α-tocopherone, and the other, designated compound B, was identified as cis-7-hydroxy-cis-8,8a-epoxy-α-tocopherone. It was also observed that under protic conditions (10% water in acetonitrile) the reaction of α-tocopherol with O ₂ ^- did not produce compounds A and B, but rather α-tocopheryl quinone, α-tocopherol dimer, α-tocopherol dihydroxy dimer, and the previously designated compound C. Compound C was identified in the present study as α-tocopheryl-quinone-2,3-epoxide.