PT-141 is a cyclic heptapeptide melanocortin receptor agonist derived from Melanotan II. It differs from MT-II by a C-terminal free acid in place of the amide. Contexx Research supplies PT-141 in Canada as a 10 mg lyophilized reference peptide for melanocortin receptor and neuroendocrine research.
PT-141 specifications
| Compound | PT-141 |
|---|---|
| Vial size | 10 mg |
| Vial capacity | 3 mL (the total liquid volume the vial can hold; not the amount of material inside) |
| Form | Lyophilized powder |
| Purity | See lot COA |
| Structure | Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH |
| CAS number | 189691-06-3 |
| Molecular formula | C50H68N14O10 |
| Molecular weight | 1025.2 g/mol |
| Storage (unopened) | −20 °C, dry, protected from light |
Research overview
PT-141 is a metabolite-like analogue of Melanotan II and keeps the cyclic α-MSH core that binds melanocortin receptors, with notable activity at MC3R and MC4R. A historical review in Peptides traces how the melanocortin peptide programme at the University of Arizona led from MT-I and MT-II to PT-141 [1].
A 2022 review in Biomolecules places PT-141 among the broader family of natural and synthetic melanocortin receptor ligands and compares receptor selectivity, signalling and structural determinants across the class [2]. It is a helpful reference when choosing a melanocortin agonist for an assay.
Animal studies have used PT-141 to examine central melanocortin circuits. A 2025 study in female Syrian hamsters, for example, analysed behavioural and neural responses to the peptide [3]. In vitro, it serves as a reference agonist in MC4R binding and cAMP signalling assays.
Selected references
- Hadley ME et al. Peptides. 2006. PubMed 16412534
- Yuan XC et al. Biomolecules. 2022. PubMed 36291616
- Borland JM et al. Neuropharmacology. 2025. PubMed 39793696
Storage and handling
PT-141 ships as a lyophilized (freeze-dried) powder. Dry material is far more stable than material in solution, so keep it in its dry, sealed state until you need it.
- Store unopened vials of PT-141 at −20 °C, dry and protected from light. Let the vial reach room temperature before opening to limit condensation.
- Prepare stock solutions in a solvent suited to your assay, label them with concentration and date, and keep them at 2–8 °C for short-term use.
- For longer storage of solutions, divide them into single-use aliquots and freeze them; avoid repeated freeze–thaw cycles.
- Handle with gloves and eye protection, following your laboratory’s standard chemical-hygiene practice.
See our guide to storing lyophilized peptides in the lab for more detail.
Quality and testing
Contexx Research independently tests every batch it releases. A lot-specific COA for PT-141 isn’t linked on this page yet. For questions about testing, contact info@contexxresearch.ca.
We don’t list purity figures in this description; the lot COA is the reference for identity and purity. Researchers should confirm identity and concentration with their own analytical methods where their protocol requires it.
Frequently asked questions
What’s included when I order PT-141 10 mg?
One sealed vial containing 10 mg of PT-141 as a lyophilized powder. Reconstitution solution is sold separately.
Does PT-141 come with a Certificate of Analysis (COA)?
Every batch Contexx Research releases is independently tested. A lot-specific COA isn’t linked on this page yet; for testing questions, contact info@contexxresearch.ca.
How fast is shipping in Canada?
Orders are processed Monday to Friday, and most orders ship within 24 hours from Mississauga, Ontario, in secure, tamper-evident packaging. Orders placed on Friday afternoon (after the 12:00 PM ET cut-off) ship on Monday, when Canada Post resumes pickup, or on the next business day if Monday is a statutory holiday. Once your order ships, delivery typically takes 1–3 business days in Ontario and Quebec and 2–6 business days in the rest of Canada, and a tracking number is emailed to you. Orders over $250 CAD shipped within Canada qualify for free standard shipping. See our Shipping Policy for details.
How should PT-141 be stored?
Store unopened vials at −20 °C, dry and protected from light. After reconstitution, keep solutions at 2–8 °C for short-term use, or freeze single-use aliquots and avoid repeated freeze–thaw cycles.
What does “research use only” mean?
“Research use only” means PT-141 is sold only as a reference material for in-vitro laboratory and analytical research by qualified professionals. It is not for use in humans or animals, not for diagnostic use, and not a drug, natural health product, food, supplement or cosmetic.
Research use only
PT-141 is sold by Contexx Research Inc. strictly as a reference material for in-vitro laboratory research and analytical use by qualified professionals. It is not a drug, natural health product, food, dietary supplement or cosmetic. It is not intended for use in humans or animals, for diagnostic purposes, or for ingestion or any other form of administration to a living organism. Nothing on this page describes or implies any effect in humans or animals. Purchasers are responsible for handling, storage and disposal in line with applicable laws and their institution’s policies. By ordering, you confirm that you are purchasing for legitimate laboratory research and agree to our Terms and Conditions.
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