A synthetic peptide analogue of the naturally occurring alpha-melanocyte stimulating hormone (a-MSH) with potential photoprotective activity. Mimicking the action of a-MSH, afamelanotide stimulates melanocytes to increase the production and release of melanin. Increased melanocyte melanin may protect against ultraviolet radiation (UVR)-initiated cellular DNA damage, oxidation of membrane proteins, and alterations in intracellular signaling processes in epidermal cells. Endogenously, a-MSH is released by skin cells in response to UVR exposure, stimulating melanocytes to produce and release melanin.