No. 2 Vol. 42, No. 3, pp. 201–217, 2008 Enhancing facial beauty: diminishing tension-caused forehead wrinkles through upper back massage

A number of papers have been published on the oxidation coupling reactions of the active intermediate of a dye precursor with an electron-rich dye coupler. At the present stage, however, little information is available about the oxidative reaction mechanism to colored oxidation products and the dye distribution inside the keratin fibers. From the results of dyeing in the presence of both reducing agent and chelate agent, we found that the coupling reaction developing oxidation dyes occurred on the outer surface in the cuticle cell phase, and that not only the cell membrane complex (CMC) regions play an important role as accumulation regions of the finished dye, but also the components of CMC contribute directly to the oxidation coupling reactions. Furthermore, we suggested from the other results that the metal ions and disulphide bond presented primarily within the intercellular materials play an important role in developing the colored oxidation dye. Then, on the basis of the general scheme of the oxidation dye process, we proposed a tentative mechanistic scheme of oxidative dyeing to account for the oxidation dying phenomenon of keratin fibers. The scheme is made up of four step-reactions.
Keywords:  oxidation dye, oxidative dyeing, precursor, coupler, active intermediate, keratin fiber, chelate agent, cell membrane complex, intercellular materials, metal ion, disulphide bond