Melanotan I (MT-1)
The linear 13-residue [Nle4, D-Phe7]-alpha-MSH analogue as freeze-dried powder in a sealed vial. Every lot is tested in the manufacturer’s own laboratory and ships with a lot certificate.
| Compound | Melanotan I Afamelanotide; [Nle4, D-Phe7]-α-MSH |
|---|---|
| CAS number | 75921-69-6 |
| Molecular formula | C78H111N21O19 |
| Theoretical mass | 1646.9 Da |
| Sequence / structure | Ac-SYS-Nle-EH-[D-Phe]-RWGKPV-NH₂ (13 residues; N-acetyl; C-terminal amide) |
| Label claim | 10 mg/vial |
| Form | Lyophilized (freeze-dried) powder or cake in a sealed glass vial with a rubber stopper and aluminium crimp cap |
| Storage, sealed | −20 °C, desiccated, dark |
| Purity specification | 99.0% or higher by RP-HPLC |
| Format | Lyophilized powder, sealed vial |
Sizes and lots
- 10 mg · 1 vial — $64.88 · lot PL-2609-065, certificate PL-26-00065
- 10 mg · Kit of 10 — $576.78 · lot PL-2609-065, certificate PL-26-00065
Melanotan I, also called MT-1 and afamelanotide, is [Nle4, D-Phe7]-alpha-MSH: the full 13-residue sequence of alpha-melanocyte-stimulating hormone with two substitutions, kept linear. This listing is a sealed vial holding 10 mg of the peptide as freeze-dried powder, acetylated at the N-terminus and amidated at the C-terminus. Research on it runs from 1980s structure-activity work on alpha-MSH analogues through early clinical studies of skin pigmentation to two randomised trials of an implant formulation in erythropoietic protoporphyria.
Melanotan I is not a milder melanotan II
The two names suggest two strengths of one product, but they are different molecules. Melanotan I keeps the whole backbone of alpha-MSH, Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2, with norleucine at position 4 in place of methionine and D-phenylalanine at position 7. Swapping out methionine removes the oxidation-prone thioether that the native hormone carries. Melanotan II is a seven-residue fragment closed into a ring by a lactam bridge.
What the research covers
A superpotent linear analogue
Alpha-MSH is a 13-residue peptide, Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH21. Structure-activity work in the 1980s produced analogues far more potent than the hormone, and in 1989 Al-Obeidi and colleagues named Ac-[Nle4,D-Phe7]-alpha-MSH, the compound now called melanotan I or afamelanotide, as one of two superpotent analogues their new designs started from1. Those designs were cyclic lactam fragments, and their potency was measured against alpha-MSH in frog and lizard skin bioassays, the standard tests of melanotropic activity at the time1. Melanotan I therefore came first; the cyclic peptides that led to melanotan II were designed from what it and its relatives had shown about the hormone1.
A 2006 review by Hadley and Dorr described the melanocortin analogues from this work as superpotent, prolonged acting and resistant to enzymatic breakdown2. Two were patented and moved into clinical testing: melanotan I, the linear peptide, and melanotan II, a truncated cyclic one2.
Clinical development
According to Hadley and Dorr, melanotan I was tested clinically in studies of skin tanning, while melanotan II went toward the diagnosis and treatment of male erectile dysfunction2. The review abstract gives no results for the tanning studies.
The largest controlled human data in these references concern a different use. Langendonk and colleagues ran two multicentre, randomised, double-blind, placebo-controlled trials of afamelanotide implants in erythropoietic protoporphyria, a photodermatosis in which light exposure causes acute pain3. The European trial enrolled 74 patients and the US trial 94; over study periods of 180 and 270 days they recorded the type and duration of sun exposure, the number and severity of phototoxic reactions, adverse events and quality of life, with photoprovocation testing in a US subgroup3. The primary end point was the number of hours of direct sunlight without pain. In the US study the median after six months was 69.4 hours in the afamelanotide group against 40.8 hours with placebo (P=0.04)3. The trial material was a solid implant, a different article from freeze-dried powder in a vial.
What is not established
The evidence in these references is narrow. Potency comes from amphibian and reptile skin assays1, the controlled human data from two implant trials in one rare disease3, and the tanning work is mentioned in a review without figures2. None of the cited abstracts measures receptor selectivity; the melanotan guide sets out what is known about it, along with afamelanotide's regulatory history.
Frequently asked questions
Is melanotan I the same as afamelanotide?
Yes. Afamelanotide is the nonproprietary name for [Nle4, D-Phe7]-alpha-MSH, the peptide also sold as melanotan I or MT-1. This vial holds that 13-residue sequence: CAS 75921-69-6, formula C78H111N21O19, theoretical mass 1646.9 Da.
How does MT-1 differ from MT-2?
They are different molecules. MT-1 is linear, 13 residues and 1646.9 Da. MT-2 is a seven-residue lactam ring of 1024.2 Da that reaches more melanocortin receptors. Findings for one cannot be carried over to the other, and SCALE Performance sells them as separate products.
How should the vial be stored?
Keep it sealed at −20 °C, dry and dark. Allow it to warm to room temperature before opening to stop condensation forming on the powder. For reconstituted solutions the safety data sheet gives 2 to 8 °C, protected from light, for a period set by your laboratory.
What does the published research on afamelanotide show?
It shows a superpotent linear alpha-MSH analogue from 1980s structure-activity work, clinical tanning studies mentioned without results in a 2006 review, and two randomised implant trials in erythropoietic protoporphyria that measured pain-free time in sunlight. None of it used freeze-dried research material.
References
- Al-Obeidi F, Castrucci AM, Hadley ME, et al. Potent and prolonged acting cyclic lactam analogues of alpha-melanotropin: design based on molecular dynamics. J Med Chem. 1989;32(12):2555-61. DOI · PubMed
- Hadley ME, Dorr RT. Melanocortin peptide therapeutics: historical milestones, clinical studies and commercialization. Peptides. 2006;27(4):921-30. DOI · PubMed
- Langendonk JG, Balwani M, Anderson KE, et al. Afamelanotide for Erythropoietic Protoporphyria. N Engl J Med. 2015;373(1):48-59. DOI · PubMed
For laboratory research use only. Not for human or veterinary consumption. Products have not been evaluated by the U.S. Food and Drug Administration and are not intended to diagnose, treat, cure or prevent any disease.