Melanoma incidence continues to rise due to intentional exposure to ultraviolet radiation (UVR) from sunlight
and indoor tanning beds. Eumelanin exhibits photoprotective effects; thus, agents that induce its synthesis offer a
means for sunless tanning without UVR damage. Herein, we report the development of two pentapeptides, P9 and P10,
capable of enhancing melanin synthesis in B16 melanoma cells by activating mushroom and mouse tyrosinases without
any effect on cell viability or proliferation. P9 and P10 significantly increased melanin content in a dose-dependent
manner comparable to the positive controls, IBMX, scoparone, and α-MSH. However, unlike IBMX and scoparone,
but similar to α-MSH, P9 and P10 were able to reverse 6BH4-dependent tyrosinase inhibition. We hypothesize that P9
and P10 allosterically activate tyrosinase and consequently enhance epidermal melanin synthesis. P9 and P10 may offer
an alternative to tanning bed use and non-photoprotective tanning products. Moreover, sustained increase of melanin
content in skin has the potential to reduce symptoms of photosensitivity disorders such as erythropoietic protoporphyria
(EPP), solar urticaria (SU) and polymorphic light eruption (PLE), which lack fully effective treatments and result
in significant morbidity.
Allosteric activation, melanin content, melanoma, pentapeptide, tanning beds, tyrosinase.
Escape Therapeutics, Inc., 5941 Optical Court, San Jose, CA 95138, USA.