Function
While Epitalon is reported to increase lifespan and reduce tumor incidence in animals, and to influence differentiation of neural and mesenchymal stem cells; is studied as an epigenetic regulatory peptide36, Melanotan I is approved in some regions for prevention of phototoxicity in erythropoietic protoporphyria and is studied as a skin-darkening, photoprotective peptide3444.
Mechanism
While Epitalon works as a synthetic tetrapeptide, Ala-Glu-Asp-Gly (AEDG), that has been shown to bind histones and modulate gene expression and chromatin state, with reported effects on pineal function, neurogenesis, and longevity in animal models36, Melanotan I is a linear 13-amino-acid analog of α-MSH (afamelanotide) that selectively activates MC1R on melanocytes, increasing eumelanin synthesis and providing photoprotection3444.
Length and Sequence
Epitalon is 4 amino acids long, whereas Melanotan I is longer as it has a length of 13 amino acids. Epitalon is made up of a sequence of Alanine, Glutamic acid, Aspartic acid, Glycine. Melanotan I is made up of a sequence of Serine, Tyrosine, Serine, Nle, Glutamic acid, Histidine, Phenylalanine, Arginine, Tryptophan, Glycine, Lysine, Proline, Valine.