The real radical generator other than main-product hydroperoxide in lipid autoxidation.

The theory of initiation in lipid autoxidation, which deals with the supply of radicals to the chain reaction, has not been substantively advanced for several decades. Most researchers have long assumed a mechanism of initiation in which main-product hydroperoxide is centrally responsible for autocatalytic radical generation. However, this paper, in which we investigate autoxidizing methyl linoleate, presents decisive evidence against such an assumption: Autoxidation-accelerating activity under mild conditions was not found in the chromatographically separated main-product hydroperoxide fraction but was found in other fractions; and highly active substances with structures containing a peroxide-linked dimer with two hydroperoxy groups were actually obtained.