During the DPPH
scavenging assay carried out in non polar and non protic solvents, such as toluene, BHT
regenerates a-tocopherol from tocopheryl radical, whereas in polar and protic solvents, like methanol, no
regeneration is observed due to a fast electron transfer reaction from the tocopheryl radical to the
reactive DPPH radical. Surprisingly, in the presence of a small amount of alcohol, the synergy is exalted
and BHT regenerates twice as much a-tocopherol due to a nucleophilic addition of short alcohols on the
BHT oxidation product, giving a new phenolic co-antioxidant.