To provide a decolorant acting on melanine formation process, bleaching or reducing pigmentation on the skin, skin hair or hair in nearly uniform pigmentation and to resist hyperpigmentation of the skin (in times when the skin manifests uneven pigmentation).

The invention relates to the specific oligonucleotide sequences and/or their derivatives. Said oligonucleotide sequences are hybridized with the gene or with a product of the gene encoding tyrosinase or with the gene or a product of the gene encoding the tyrosinase-related protein 1 (TRP-1). The invention also relates to the use of the new oligonucleotide sequences as decolorant or skin whitening agents in a cosmetic composition or a dermatological composition.