Melanotan II and PT-141: A Guide to Melanocortin Research Peptides

Few compound families have a better origin story than the melanocortins. University of Arizona researchers studying pigmentation synthesised analogues of α-MSH, the body's melanocyte-stimulating hormone — and the observations that followed launched two separate research fields from one molecular scaffold.

The receptor family

Melanocortin receptors come in five subtypes, MC1R through MC5R, scattered across very different tissues. MC1R governs pigmentation. MC3R and MC4R live in the central nervous system and are associated in the literature with energy balance and signalling cascades far removed from skin. One ligand family, many doors — which is exactly what makes these peptides such productive research tools.

Melanotan II

Melanotan II is a cyclic heptapeptide analogue of α-MSH, considerably more potent and stable than the native hormone. It binds non-selectively across MC1R, MC3R, MC4R and MC5R, making it the broad-spectrum probe of the family. In models it is most associated with MC1R-mediated melanogenesis pathways. It is also notably light-sensitive — store it dark and cold.

PT-141 (Bremelanotide)

PT-141 is what happened when researchers modified Melanotan II and the pharmacology shifted: a metabolite-derived analogue with stronger relative activity at MC4R — the centrally-expressed receptor. It eventually completed clinical development under the name Vyleesi, which for research purposes means an unusually rich published record for a peptide of its size.

Why study them together

The pair make an elegant selectivity comparison: near-identical scaffolds with different receptor-subtype weightings. Comparative binding work across the MC receptor family is a staple of GPCR research, and both compounds ship from our Australian facility HPLC-verified with batch documentation available on request.

For laboratories and peptide businesses buying at volume, wholesale trade packs — sourced and tested in Australia — are available through our wholesale and white-label page.

All compounds discussed are for in-vitro laboratory research only and are not for human or veterinary use.