Synopsis

In an attempt to develop hair dye products that give more natural-looking colors, some of the basic steps from the natural biosynthetic pathway to melanin have been imitated chemically. Our hair coloring process starts with 3,4-dihydroxyphenylalanine (dopa). By careful selection of oxidant and oxidation conditions, dopa is converted on hair to 5,6-dihydroxyindole in high yield. This indole has been known for many years to be the immediate precursor to the black eumelanins, and it can be readily polymerized in situ to dye the hair an intense black color. Additionally, the natural process produces the red and yellow pheomelanins by incorporating sulfur-containing nucleophiles uch as cysteine into the melanogenic process. We have also found that significant color changes can be produced by adding a variety of nucleophiles to the system, including cysteine and other thiols. By these means, a wide range of shades can be produced on hair under conditions acceptable to the user of the hair dye. Performance of the dyed hair appears to be comparable to that of current permanent dyes and is clearly superior in both application technique and performance to the alternative natural dye products available today