PT-141 (Bremelanotide) — Compound Overview
A researcher-focused overview of PT-141: its chemistry as a cyclic melanocortin analogue, its relationship to Melanotan-2, and how each batch is documented.
Last updated: 2026-08-21 · By: Index Peptides technical team
Key facts about PT-141
| Compound | PT-141 |
|---|---|
| CAS number | 189691-06-3 |
| Molecular formula | C50H68N14O10 |
| Molecular weight | 1025.2 g/mol |
| Sequence | cyclo Ac-Nle-[Asp-His-D-Phe-Arg-Trp-Lys] |
| Listed formats | 10mg per vial |
| Intended use | In-vitro laboratory research only |
What is PT-141?
PT-141, also known by the International Nonproprietary Name bremelanotide, is a cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone (α-MSH). It is a structural derivative of Melanotan-2 in which the C-terminal amide is replaced by a free carboxylic acid. It binds melanocortin receptors, a family of G-protein-coupled receptors.
Chemistry and structure
PT-141 carries CAS registry number 189691-06-3, molecular formula C50H68N14O10 and a molecular weight of approximately 1025.2 g/mol. The peptide is cyclised through a lactam bridge between aspartate and lysine side chains (cyclo Ac-Nle-[Asp-His-D-Phe-Arg-Trp-Lys]), which constrains its conformation relative to linear α-MSH analogues.
Supply status
Index Peptides supplies PT-141 strictly as a research chemical for in-vitro laboratory research. Products are sold exclusively to qualified researchers and licensed laboratories. It is not for human or veterinary use.
PT-141 in the research literature
PT-141 appears in the melanocortin-receptor literature as a high-affinity cyclic ligand, making it a common tool compound in receptor-binding and signalling assays. Researchers comparing data across papers should confirm which salt form and purity grade was used — another reason batch-level COA documentation matters.
Form, handling and storage
Supplied as a lyophilised powder in a sealed vial. Store at -20°C, desiccated and protected from light, per the batch record.
Batch documentation at Index Peptides
Review the published certificate for the exact lot, including the laboratory, report date and analytical results actually reported. HPLC purity alone does not confirm LC-MS identity. Contact us before ordering if a required result is not published.
Frequently asked questions
Who is PT-141 supplied to?
Index Peptides supplies PT-141 exclusively to qualified researchers and licensed laboratories, for in-vitro research only. It is not for human or veterinary use.
What is the relationship between PT-141 and Melanotan-2?
PT-141 is a derivative of Melanotan-2 in which the terminal amide group is replaced by a carboxylic acid. Both are cyclic melanocortin-receptor analogues with distinct CAS numbers and masses.
How is each batch verified?
Reversed-phase HPLC for purity and LC-MS for identity, with the COA published on the product page and batch lookup by lot number.
What is the shelf life of PT-141?
As supplied (lyophilised powder in a sealed vial), PT-141 is stored at -20C, desiccated and protected from light. Long-term stability is documented per batch on the certificate of analysis; treat the batch record as the authoritative shelf-life reference for that lot.
What is the difference between the sizes?
The difference is the nominal peptide content per vial. PT-141 is supplied as 10mg single-compound vials. Every format carries the same batch documentation and purity testing.
What does the certificate of analysis show?
Review the published certificate for the exact lot, including the laboratory, report date and analytical results actually reported. HPLC purity alone does not confirm LC-MS identity. Contact us before ordering if a required result is not published.
References
Research use only. Not for human or animal consumption.