Patent ID: 7594936

Claim:
A dye composition for dyeing keratin fibers comprising, in an appropriate dyeing medium, at least one aldehyde precursor, at least one enzyme able to generate an aldehyde from the at least one aldehyde precursor, and at least one heteroaromatic hydrazone able to generate a colored substance by reaction with an aldehyde; wherein the at least one heteroaromatic hydrazone is chosen from hydrazones having the formula: Ar═N—NH 2 wherein Ar is chosen from heterocycles with 5 or 6 links comprising at least one nitrogen atom; and condensed polycyclic heteraromatic groups with 9or 10 links comprising at least one nitrogen atom, and wherein Ar can optionally be substituted on the nitrogen atoms by a substituent chosen from C 1 to C 4 alkyls, C 1 to C 4 alcohols, and C 1 to C 4 ethers.