PT-141 (CAS 189691-06-3), also known as Bremelanotide, is a synthetic cyclic heptapeptide melanocortin receptor agonist with a molecular weight of 1025.22 g/mol. Its structure, Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH, features an N-terminal acetylated norleucine residue and a lactam bridge between Asp and Lys forming the characteristic macrocyclic ring. PT-141 was derived from the linear alpha-MSH analogue Melanotan II through selective C-terminal modification and retains the His-D-Phe-Arg-Trp pharmacophore core. Produced via solid-phase peptide synthesis, Bremelanotide is primarily associated with melanocortin-3 receptor (MC3R) and melanocortin-4 receptor (MC4R) signalling pathways.

PT-141 has been investigated in preclinical melanocortin receptor pharmacology, where its cyclic structure and receptor selectivity profile have been characterised as the pharmacological basis for its use in studying MC3R and MC4R-mediated central signalling. Unlike the endogenous melanocortin ligands alpha-MSH and ACTH, PT-141 incorporates non-natural amino acid substitutions including norleucine and D-phenylalanine that have been characterised as altering its receptor binding characteristics and metabolic stability. In vitro receptor pharmacology studies have examined Bremelanotide’s binding affinity across the melanocortin receptor family (MC1R–MC5R), characterising its Gαs-coupled cAMP signalling profile and receptor subtype selectivity, documenting MC3R and MC4R as the primary receptor targets underlying PT-141’s central melanocortinergic pharmacological activity [1]. In vivo rodent studies have investigated central MC3R/MC4R activation within hypothalamic melanocortinergic circuitry, documenting that central administration of Melanotan II in rodent models activates hypothalamic MC4R-mediated signalling pathways and characterising central melanocortinergic circuit engagement as a defined in vivo pharmacological consequence of cyclic melanocortin receptor agonism [2], making PT-141 a key reference compound in melanocortin receptor pharmacology research examining MC3R and MC4R-selective cyclic agonist activity in central signalling contexts.

PT-141 is manufactured in a cGMP compliant laboratory to a guaranteed purity of 98% or above. Every batch is independently tested using HPLC and MS-UPLC analysis before dispatch. Vials are vacuum sealed and stored in a temperature controlled, monitored cold storage system. Certificates of Analysis are available on request.

Sold strictly for in vitro research purposes only. Not for human consumption. Intended for use by qualified researchers in laboratory settings only.

Editorial Team

Dr. Martina Rossi, PhD

Scientific Contributor and Reviewer

Reviewed and approved 14 June 2026

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