# Melanotan I (Afamelanotide)

> Afamelanotide — a 13-residue α-MSH analogue for melanocortin receptor studies

All products are sold strictly for laboratory research use only. Not for human or veterinary use.

- Web page: https://peptidemedixeu.com/en/products/melanotan-1/
- Brand: Peptide Medix EU
- Category: [Cosmetic Signal Peptides](https://peptidemedixeu.com/en/collections/cosmetic-peptides/)
- Purity: ≥99% by HPLC, confirmed by mass spectrometry; lot-matched COA
- CAS number: 75921-69-6
- from €55 (EUR)

## Sizes and prices (EUR)

| Size | Price | SKU |
| --- | --- | --- |
| 10 mg | €55 | MELANOTAN-1-10-MG |
| 20 mg | €97 | MELANOTAN-1-20-MG |

_Catalog prices at build time; the web page and checkout are authoritative._

## Specifications

- **CAS number:** 75921-69-6
- **Molecular formula:** C78H111N21O19
- **Molecular weight:** 1646.87 g/mol
- **Amino acid sequence:** Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2
- **Peptide class:** Linear α-MSH (melanocortin) analog, tridecapeptide
- **Form:** White to off-white lyophilized powder in a sealed glass vial
- **Purity:** ≥99% by HPLC, confirmed by mass spectrometry; lot-matched COA
- **Available sizes:** 10 mg, 20 mg
- **Solubility:** Bacteriostatic water or sterile water; aqueous stocks kept cold and dark
- **Storage (lyophilized):** −20 °C, sealed, protected from light and moisture
- **Storage (reconstituted):** 2–8 °C, short study window; avoid repeated freeze–thaw
- **Primary target:** Melanocortin receptors, with reported preference for MC1R
- **Research areas:** Melanogenesis, eumelanin synthesis, MC1R signalling, UV-response models

## Description

Melanotan I, known too as afamelanotide, is a synthetic analogue of alpha-melanocyte-stimulating hormone (α-MSH) comprising 13 amino acids. Compared with the natural hormone it has two intentional changes — norleucine in position 4 and D-phenylalanine in position 7 — which emerged from structure–activity research on melanocortin ligands and which slow enzymatic degradation without weakening receptor binding. It is a linear tridecapeptide with an amidated C-terminus, and in the lab it acts as a long-lasting melanocortin receptor agonist.

Where the cyclic lactam Melanotan II is constrained, Melanotan I retains the open α-MSH chain and is described as having a narrower melanocortin profile, acting most strongly at MC1R, the subtype found on melanocytes. This relative selectivity is why it appears chiefly in pigmentation, photobiology and receptor-signalling research, not in appetite or sexual-behaviour models, which need broader melanocortin coverage.

## Frequently asked questions

### How does Melanotan I compare with natural α-MSH?

It is a synthetic 13-residue version of alpha-melanocyte-stimulating hormone carrying norleucine at position 4 and D-phenylalanine at position 7. Those substitutions reportedly delay enzymatic breakdown and prolong receptor engagement, so in lab assays the analogue outlasts the native hormone as a melanocortin agonist.

### Melanotan I versus Melanotan II — what's the difference?

MT-1 is the full-length, linear peptide, with activity concentrated at MC1R. MT-2 is a shorter cyclic lactam that reaches a wider range of melanocortin receptors, MC3R and MC4R included. Comparing them helps separate pigment-pathway signalling from broader melanocortin effects.

### Has the lot been checked by an outside lab, and can I read the COA?

Yes. An independent laboratory confirms identity and purity of each production lot using HPLC plus mass spectrometry, and you may request the lot certificate before purchase; it gives lot number, assay value and test date for your files.

### Which vial sizes exist, and what's inside?

10 mg and 20 mg lyophilised vials containing nothing but the freeze-dried peptide — no diluent, preservative or excipient — so your lab decides the reconstitution vehicle and final concentration.

### How should powder and solutions be kept?

Store the sealed lyophilisate at −20 °C away from light and humidity, where it lasts a long time. After dissolving, refrigerate at 2–8 °C in the dark and use within a short, defined period rather than keeping it long term.

### Which solvent is typical in the lab?

Bacteriostatic or sterile water — the peptide dissolves easily. Let the diluent run gently down the glass and swirl rather than shake. Record the solvent together with the concentration, since it influences stability in solution.

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All products offered on this website are intended solely for in-vitro laboratory research and development by qualified professionals. They are not drugs, foods, cosmetics or dietary supplements, and are not intended to diagnose, treat, cure or prevent any disease. Products must not be introduced into humans or animals in any manner. By purchasing, you confirm that you are a qualified researcher and accept full responsibility for handling and storage in accordance with applicable laws.

Peptide Medix EU · https://peptidemedixeu.com/en/products/melanotan-1/