Function
While Matrixyl is a widely used cosmetic peptide with evidence of stimulating extracellular matrix synthesis and reducing wrinkle appearance in skin-care formulations48, Melanotan II is studied as a tanning and libido-enhancing agent; increases melanin production and can reduce food intake and modulate sexual arousal in animal models and humans3545.
Mechanism
While Matrixyl works as a palmitoylated pentapeptide, Pal-Lys-Thr-Thr-Lys-Ser (Pal-KTTKS), that acts as a matrikine, signaling to dermal fibroblasts to increase production of collagen, elastin, fibronectin, and other ECM components4858, Melanotan II is a cyclic heptapeptide melanocortin analog (Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2) that acts as a non-selective, high-potency agonist at MC1R, MC3R, MC4R, and MC5R, influencing pigmentation, appetite, and sexual behavior3545.
Length and Sequence
Matrixyl is 5 amino acids long, whereas Melanotan II is longer as it has a length of 7 amino acids. Matrixyl is made up of a sequence of Lysine, Threonine, Threonine, Lysine, Serine. Melanotan II is made up of a sequence of Nle, Aspartic acid, Histidine, Phenylalanine, Arginine, Tryptophan, Lysine.