alpha-Tocopheryl quinone is converted into vitamin E in man

The conversion of alpha-tocopheryl quinone into alpha-tocopherol in humans has been demonstrated. A male subject was given an oral dose of 400 mg of alpha-3,5-[((CH3)-H-2)(2)]-tocopheryl quinone with an evening meal. Analysis of plasma 15 h later by lipid extraction and subsequent GC-MS single ion monitoring revealed the presence of alpha-[5,7((CH3)-H-2)(2)]-tocopherol at a concentration of 0.4 mu M, representing 0.8% of the total tocopherol in the plasma sample. This experiment clearly demonstrates that orally administered alpha-tocopheryl quinone is converted in a low overall yield to alpha-tocopherol in humans. The conversion to alpha-tocopherol of that portion of the quinone dose which was actually absorbed into the blood stream may, however, have been fairly efficient. Copyright (C) 1997 Elsevier Science Inc.