Melanotan I
Melanotan I (afamelanotide) is a 13-residue linear analogue of α-melanocyte-stimulating hormone, [Nle4, D-Phe7]-α-MSH, with an N-terminal acetyl group and a C-terminal amide.
- TypePeptide
- FormulaC78H111N21O19
- Average mass1646.85 g/mol
- CAS75921-69-6
- Vesta listings1
Reference page for laboratory use · updated 2026-10-30
Overview
Melanotan I at a glance
Afamelanotide was made by replacing two residues of α-MSH to increase potency and stability. Its pharmacokinetics and pharmacodynamics are described in the clinical pharmacology literature.
Vesta lists a single product named Melanotan I/II. Check the batch documents to confirm which of the two peptides the vial contains; their masses are very different.
Structure
The sequence is Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2. The calculated formula matches PubChem exactly.
Identity
Identity data
| Name | Melanotan I |
|---|---|
| Also written as | Afamelanotide, NDP-MSH |
| Type | Peptide |
| Research area | Melanocortin peptides |
| Molecular formula | C78H111N21O19 |
| Monoisotopic mass | 1645.8365 Da |
| Average molecular weight | 1646.85 g/mol |
| CAS number | 75921-69-6 |
| Sequence | Ac-Ser-Tyr-Ser-Nle-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2 |
| PubChem record | CID 16197727 |
The formula was calculated independently from the written sequence and matches the PubChem record exactly. Reference data retrieved on 2026-10-30. Compare these values with the batch certificate of analysis, using the compound identity file template.
Expected values
Mass spectrometry reference
Ions calculated from the monoisotopic mass 1645.8365 Da. Use them to check an LC-MS result; for larger peptides the instrument usually reports a deconvoluted mass close to 1646.8 Da instead.
| Ion | m/z |
|---|---|
| [M+H]+ | 1646.8438 |
| [M+2H]2+ | 823.9255 |
| [M+3H]3+ | 549.6194 |
Read the guide to average and monoisotopic mass for how these values are calculated.
Quality
Analytical notes for batch documents
- Melanotan I (about 1646.8 Da) and melanotan II (about 1024.2 Da) are easy to tell apart by mass.
- Tryptophan is the main oxidation site. The methionine at position 4 of α-MSH was replaced by norleucine to remove an oxidation-prone residue.
- Mass shifts to look for in this sequence: tryptophan oxidation (+15.995 Da).
- The molecular weight of a vial of powder includes counter-ions and water; the share of the powder that is peptide is the net peptide content.
Vesta listings
Melanotan I formats and prices
| Product | Per vial | SKU | Price per kit | Price per vial |
|---|---|---|---|---|
| Melanotan I/II | 10 mg | MT-1/MT-2 | $104.48 | $10.45 |
Vesta lists one product called Melanotan I/II. Confirm from the batch documents which of the two it contains.
Prices are per kit of 10 vials in US dollars. Shipping is paid by the customer and is shown in the cart. Volume savings of 5 %, 8 % and 10 % apply from $350.00, $600.00 and $1,000.00. See the full price list.
Published literature
Selected scientific literature
Bibliographic details were read from PubMed on 2026-10-30. The papers are listed for scientific reference; Vesta makes no claim about the use of its research materials in people or animals.
- Pharmacokinetics and Pharmacodynamics of Afamelanotide and its Clinical Use in Treating Dermatologic DisordersMinder EI, Barman-Aksoezen J, Schneider-Yin X et al. · Clin Pharmacokinet · 2017 · PMID 28063031
Questions
Frequently asked questions
What is Melanotan I?
Melanotan I (afamelanotide) is a 13-residue linear analogue of α-melanocyte-stimulating hormone, [Nle4, D-Phe7]-α-MSH, with an N-terminal acetyl group and a C-terminal amide.
What is the molecular weight of Melanotan I?
Melanotan I has the formula C78H111N21O19, an average molecular weight of 1646.85 g/mol and a monoisotopic mass of 1645.8365 Da. A salt form, a different counter-ion or a metal complex changes the molecular weight printed on a certificate of analysis, so compare like with like.
How can I check the identity of a batch of Melanotan I?
Compare the intact mass measured by LC-MS with the expected values on this page, for example [M+2H]2+ at m/z 823.9255. Confirm that one main HPLC peak carries that mass and that the batch code on the report matches the vial. The guides on mass spectrometry and on certificates of analysis explain each step.
Which Melanotan I products does Vesta list?
Vesta lists 1 product for Melanotan I: 10 mg per vial in kits of 10 vials. Prices are shown per kit in US dollars, and shipping is paid by the customer.