When alpha-tocopherol (α-TOH) neutralizes a free radical, such as a lipid peroxyl radical (LOO·), it becomes oxidized itself, forming the alpha-tocopheroxyl radical (α-TO·), which can promote the oxidation of lipoprotein lipids under certain conditions in the test tube (Reaction 1). When the reduced form of coenzyme Q (CoQH2) reacts with α-TO·, α-TOH is regenerated and the semiquinone radical (CoQH·) is formed (Reaction 2). It is possible for CoQH· to react with oxygen (O2) to produce superoxide (O2·-), which is a much less oxidizing radical than LOO· (Reaction 3a). Alternatively, CoQH· can also reduce α-TO· back to α-TOH, resulting in the formation of fully oxidized coenzyme Q (CoQ), which does not react with O2 to form O2·- (Reaction 3b).