The use of antisense strategy to modulate human melanogenesis

Skin without significant dyschromia is an aesthetic goal of people worldwide. Current options for lightening skin could have significant drawbacks. The antisense strategy may be a viable alternative. The reactions in melanogenesis are catalyzed mainly by tyrosinase, tyrosinase-related protein 1 (TRP-1), and TRP-2. Activation of tyrosinase is associated with phosphorylation by protein kinase C-betaI (PKC-betaI) and formation of a complex between phosphorylated tyrosinase and TRP-1. The aim of this study was to use 2 antisense oligonucleotides to modulate the synthesis of the tyrosinase/TRP-1 complex, PKC-beta, or both by interacting with the targeted mRNA, thus whitening skin by interfering with melanogenesis at the translational level.

In the in vitro study, the effect of the antisense oligonucleotides was evaluated by measuring the rate at which dihydroxyphenylalanine (DOPA) oxidase transforms L-DOPA to DOPAchrome in the pathway for melanin biosynthesis. A reduction in the reaction rate compared to the controls corresponded to a decrease in the enzyme activity and, consequently, to a reduction of the formation of melanin pigments. To evaluate the in vivo lightening effect of the antisense oligonucleotides, 30 Asian women volunteers with pigmented spots on both hands applied the test product twice daily for 8 weeks. The test product was applied to 2 marked-off areas of the hand: a pigmented spot (to evaluate the effect of the test product on the color of the spot) and a nonpigmented spot area (to evaluate the effect of the test product on normal skin pigmentation). The lightening effect was evaluated by comparing chromametric and mexametric parameters before treatment, after 4 weeks, and after 8 weeks.

In vitro DOPA-oxidase activity was inhibited by 13% in melanocytes treated with the antisense sequence for PKC-BI alone, by 16% with the antisense sequence for TRP-1 alone, and by 36% with the association of 2 sequences. The inhibiting effect with both sequences required the specific sequences with nonreversed polarities. In vivo clinical results showed statistically significant whitening in both pigmented spots and nonpigmented spots when the test product was applied twice daily for 8 weeks by up to 30 Asian women.

The association of TRP-1 and PKC-betaI antisense molecules significantly increased the inhibition of tyrosinase activity on human melanocytes. Antisense oligonucleotides are a new generation of active cosmetic ingredients that offer unprecedented specificity, biological stability, and safety in lightening skin. This is the first report of positive results in a cosmetic based on the use of these new active agents.