The transdermal inhibition of melanogenesis by a cell-membrane-permeable peptide delivery system based on poly-arginine

Topical therapy is the most favored form of treatment for whitening against hyper-pigmentation and sunburn because it lends itself to self-administration, patient compliance and an absence of systemic adverse effects. However, high-molecular-weight, hydrophilic chemicals are difficult to use as transdermal delivery drugs and the use of topical drugs has been highly limited. There are now many potent tyrosinase inhibitors, for example, sulfite or kojic acid, but the efficacy of their skin transduction remains a big problem. Furthermore, melanogenesis inhibitors from natural sources have great potential, as they are considered to be safe and largely free from adverse side effects. We applied 11-arginine (11R), a cell-membrane-permeable peptide, as a transdermal delivery system with a skin delivery enhancer, pyrenbutyrate. We performed intracellular screening for melanogenesis inhibitors with 11R fused with several kinds of tyrosinase inhibitory peptides from natural sources. Of 28 tyrosinase peptides, 13 melanin synthesis inhibitory peptides were selected. Peptide No. 10 found in gliadin protein, a wheat component, most strongly inhibited melanin production. This No. 10 peptide, of only 8 amino acids, fused to 11R showed no cytotoxicity and inhibited melanin synthesis as determined through melanin content measured using an absorption spectrometer and observation with a transmission electron microscope. Next, we transduced this 11R-No. 10 into skin with an 11R transdermal delivery system after previous treatment with pyrenbutyrate and performed daily repetitive topical application for two weeks against a UV-induced sun-tanning guinea pig model. We observed a whitening effect in a model skin sample by Masson-Fontana staining and the 11R-No. 10 peptide-applied area showed significant melanogenesis inhibition. These results show that 11R using a transdermal drug delivery system with melanogenesis inhibitory peptide is a very safe and promising method for applications from cosmetics to the pharmaceutical industry.