Melanotan-II — 8mg

Melanotan-II (MT-II) is a synthetic cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (α-MSH), developed at the University of Arizona in the 1980s as a photoprotective research compound. Its cyclic lactam structure — formed by an amide bond between Asp⁵ and Lys¹⁰ — confers high metabolic stability and broad-spectrum melanocortin receptor agonism across MC1R, MC3R, MC4R, and MC5R. The original research aim was to produce endogenous melanin synthesis via MC1R activation as a mechanism for skin cancer prevention through increased natural pigmentation, a direction that has produced both academic research and substantial off-label use of the compound.

Mechanistically, MT-II's activity spans multiple melanocortin-mediated pathways. MC1R activation in melanocytes drives eumelanin synthesis, producing darkening of skin and hair independent of UV exposure. MC3R and MC4R activation in the central nervous system modulates appetite (producing anorexic effects) and sexual arousal — the latter observation eventually led to the structural refinement of MT-II into PT-141 (bremelanotide), which selectively targets the sexual function pathway. MC5R activation produces effects on exocrine gland function and lipolysis that are still being characterized in research contexts.

The compound's broad receptor profile is both its research utility and its practical complication. Because it simultaneously activates multiple melanocortin pathways, subjects frequently experience concurrent effects — pigmentation changes, appetite suppression, spontaneous erections in males, nausea — that must be accounted for in any research protocol. MT-II is not FDA-approved for any indication, and its successor compounds (PT-141 for HSDD, afamelanotide/Scenesse for erythropoietic protoporphyria) have inherited narrow-indication regulatory pathways. Research applications today focus on the mechanistic study of melanocortin receptor pharmacology, photoprotection research in dermatology, and comparative studies against selective melanocortin agonists.