MC4 receptor
Literature focuses on the centrally expressed MC4 receptor rather than peripheral melanocortin subtypes.
≥99% Purity · HPLC 
Independently verified
PASS
- Lot
- RFX-2606-062
- Purity (HPLC)
- 99.4%
- Identity
- LC-MS confirmed
- Tested
- June 2026
- Analysed by
- Independent U.S. laboratory
These are results measured on this lot. Full material specification is in Know your compound.
Melanocortin Peptide
PT-141
A cyclic heptapeptide melanocortin agonist with MC4R-focused literature.
$45.00
$22.50 per vial with BOGO
Buy 1, Get 1 Free — sitewide Every second vial is free — applied automatically in the cart.
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- Ships from the US
- Discreet packaging
- Free shipping $100+
Research use only — not for human or veterinary use, diagnostic or therapeutic.
Researchers also added Complete the bench setup
Know your compound
What is PT-141?
PT-141 (bremelanotide) is a cyclic heptapeptide derived from the Melanotan II scaffold. It is a metabolite-derived refinement of that molecule, developed toward activity at the MC4 receptor rather than the broad melanocortin activity of its parent.
That receptor shift is the whole reason the compound exists as a separate entity. MC4R is expressed centrally rather than in skin, and the published literature on this compound therefore concerns central nervous system pathways rather than the pigmentation endpoints associated with MC1R engagement.
Supplied as a lyophilized powder for laboratory research use only, with a lot-specific Certificate of Analysis. Nothing here describes an approved therapy or a use in humans.
- N-terminusAcetyl
- C-terminusFree acid (–COOH)
- CyclisedA side-chain-to-side-chain amide between the Asp2 β-carboxyl and the Lys7 ε-amine, enclosing residues 2–7. This is a lactam, not a disulfide — the molecule contains no sulfur at all.
3D model
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Sequence
- Acetyl
- 1 Nle
- 2 Asp
- 3 His
- 4 Phe D
- 5 Arg
- 6 Trp
- 7 Lys
- Free acid (–COOH)
- Hydrophobic
- Acidic
- Basic
Read left to right from the N-terminus. Mass spectrometry checks each lot against this sequence — that result is the “Identity” line on the certificate.
Identity
What the molecule is.
- Amino acids
- 7 (cyclic)
- How many residues make up the chain.
- Molecular formula
- C50H68N14O10
- The atom count in a single molecule.
- Molecular weight
- 1025.18 g/mol
- The mass of one mole. You need this figure to calculate concentration when reconstituting.
- CAS
- 189691-06-3
- The registry number that identifies this substance unambiguously in chemical databases.
- Classification
- Melanocortin receptor agonist
- The research category this compound is grouped under.
Verification
How we know the material matches the label.
- Purity
- ≥99% (RP-HPLC, per lot)
- The share of the material that is the target compound, measured by reverse-phase HPLC on every lot — not a blanket brand claim.
- Identity method
- LC-MS confirmed
- Mass spectrometry compares the material against the expected sequence to confirm it is the right molecule.
- Documentation
- Certificate of Analysis, per lot
- The certificate for your specific lot is published before it ships and stays searchable by lot number.
Handling
What arrives, and how it is kept.
- Form
- Lyophilized powder
- The physical state the vial arrives in.
What the literature examines
Studied pathways
Summaries of what published research has investigated. Preclinical unless stated otherwise — not claims about this product.
Derived from Melanotan II
Developed from the cyclic α-MSH scaffold, and the two are routinely compared in published melanocortin work.
Central pathways
Preclinical studies examine central nervous system signalling rather than dermatological endpoints.
Certificate of Analysis
Every vial ships with its own report
Not a brand-wide spec sheet — a lot-specific certificate from an independent laboratory, published before the lot ships and searchable by lot number forever.
- Lot-specific HPLC purity and LC-MS identity
- Raw chromatogram attached to the certificate
- Signed by the analysing laboratory
- Permanent public archive, searchable by lot ID
Independent U.S. laboratory
Certificate of Analysis · RFX-2606-062
| Test | Specification | Result |
|---|---|---|
| Purity (HPLC) | ≥ 99.0% | 99.4% |
| Identity (LC-MS) | Conforms | Conforms |
| Appearance | White powder | Conforms |
| Net content | Label claim | Conforms |
Questions
PT-141 FAQ
Is PT-141 approved by the FDA?
No. PT-141 is not an FDA-approved drug and is not approved for human or veterinary use. It is supplied exclusively as a research material for laboratory use, and it is not intended to diagnose, treat, cure, or prevent any disease.
Does this lot come with a Certificate of Analysis?
Yes. Every lot is assayed by an independent U.S. laboratory for purity and identity, and the certificate for the lot you receive is published in our COA library — you can read it before you order.
How is purity determined?
Purity is quantified by reverse-phase HPLC against a reference standard, and identity is confirmed by mass spectrometry. Both results appear on the lot certificate.
How should this be stored?
Lyophilized material is typically stored cold and protected from light. Handling and storage are the responsibility of the receiving laboratory; refer to the lot documentation for specifics.
How does the buy-one-get-one offer work?
Every second vial is free, sitewide and automatically. Add two vials and you pay for one; add six and you pay for three. Compounds can be mixed, there is no code, and there is no limit.
When will my order ship?
Orders are processed promptly and shipped with tracking. Free US shipping applies over $100; Priority shipping is $8.95 otherwise.
The guarantee
99.4% pure — or your money back.
Have any lot independently re-tested. If the results don't match the purity printed on its published certificate, we refund the order in full — no returns, no argument.
Test it yourselfSend any vial to a lab of your choosing.
Published firstThe certificate goes public before the lot ships.
Full refundResults that don't match mean your money back.
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