Description
PrymaLab · Research Use Only
Melanotan 1 (MT-1) 10mg
An approval that belongs to an implant, not to the molecule
Almost nothing in this catalogue holds an approval anywhere. Melanotan 1 does, under the name afamelanotide, and it is worth being precise about what that approval covers. It was granted to a specific manufactured article, a bioresorbable implant, and a vial of lyophilized powder is not that article.
Specification Table
| Property | Value |
|---|---|
| Compound | Melanotan I, also called afamelanotide |
| CAS number | 75921-69-6 |
| Sequence | Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2 |
| Residue count | Thirteen. The full length of the parent |
| Architecture | Linear. There is no ring and no bridge |
| Parent hormone | Alpha-melanocyte stimulating hormone, also thirteen residues |
| Substitution one | Norleucine replaces methionine at position 4 |
| Substitution two | D-phenylalanine replaces L-phenylalanine at position 7 |
| Molecular formula | C78H111N21O19 |
| Molecular weight | Approximately 1646.8 for the free base |
| Termini | Acetylated at the N terminus, amidated at the C terminus |
| Receptor preference | Selective for the melanocortin 1 receptor |
| Approved article | A 16 milligram bioresorbable subcutaneous implant |
| Approval history | European authorisation in 2014, United States approval in October 2019 |
| Approved indication | Erythropoietic protoporphyria, a rare inherited condition |
| This article | 10mg lyophilized powder in a vial. Not the approved formulation |
| Storage | Sealed at minus 20°C. Protect from light |
What Does the Melanotan 1 Approval Actually Cover?
Regulatory approval is granted to a product, not to a chemical. Melanotan 1 illustrates the difference cleanly.
The dossier that supported this one described a 16 milligram bioresorbable implant placed subcutaneously, releasing its contents over a period measured in weeks rather than minutes.
European authorisation came in 2014 and United States approval followed in October 2019, both for a rare inherited condition affecting light tolerance.
The approval attaches to that implant, at that quantity, with that release profile, for that indication.
A vial of lyophilized powder shares a molecule with the approved product. Nothing else is shared.
It has no controlled release element, no established release rate, and no manufacturing dossier behind it.
This distinction is not a technicality invented for a compliance statement. It is how the regulatory system is constructed, and it is the reason a generic version of an approved drug has to demonstrate equivalence of the formulation rather than merely of the active substance.
For a researcher the practical consequence is about the literature rather than about the paperwork.
The controlled human data on this compound was generated with the implant, and figures from that work describe an exposure profile the vial cannot reproduce.
One further point on why this distinction is raised on a product page rather than left to a footnote.
An approval is the single most persuasive thing that can be said about a compound, and it travels badly.
A statement that a molecule is approved is true here and tells a reader almost nothing useful, because it omits the article, the quantity, the release profile and the indication.
Stating all four is longer and it is the only version that supports a decision.
Why Does the Dosage Form Change the Data?
A melanotan 1 implant and a bolus of dissolved peptide produce different exposure curves from the same total quantity.
The implant delivers a low, sustained level over an extended period. A dissolved bolus produces a sharp peak followed by clearance.
Peak concentration and time above a threshold are different quantities, and receptor systems do not respond to total exposure alone.
Melanocortin receptors are G protein-coupled and subject to desensitisation and internalisation on sustained engagement, which means a sustained low level and an intermittent high one can produce genuinely different outcomes at the same integrated exposure.
That is a general property of the receptor class rather than a claim specific to this molecule.
The consequence for reading the literature is straightforward. Any figure drawn from the implant work describes the implant.
Langendonk and colleagues published the controlled trial data in 2015, and the design, the quantity and the release profile in that work all belong to the implant article.
Carrying a number from it into a study using dissolved peptide requires an argument, and the argument is rarely made.
The earlier literature is a different matter, since much of the original characterisation used injected material and is closer in form to what a vial supports.
A practical way to handle this when reading is to note the article alongside every figure taken from the literature.
A record that says a number came from the implant work is a record that can be argued with.
A record that says only that a number came from the published literature on the compound has lost the information that decides whether the number applies.
This is the same discipline the fragment and species questions require elsewhere in this catalogue. It applies to formulation instead of to sequence.
How Does It Differ From Melanotan 2?
Melanotan 1 and melanotan 2 are frequently discussed as though they were versions of one thing, and structurally they are quite far apart.
This molecule keeps all thirteen residues of the parent hormone and stays linear. Its sibling keeps seven of them and closes them into a ring.
What the two share is the pair of substitutions: norleucine for methionine at position 4, and D-phenylalanine at position 7.
Those two changes came out of the same programme and appear across the melanocortin analogue literature, because they solve two general problems rather than one specific one.
The norleucine removes an oxidisable sulfur. The D residue resists proteolysis and shifts the local backbone geometry.
The difference in receptor behaviour follows from the difference in architecture rather than from the substitutions.
This molecule is described as selective for the melanocortin 1 receptor rather than active across the family. The cyclic sibling engages the family more broadly, which the melanotan-ii pages cover in the detail that comparison deserves.
For experimental purposes the selectivity is the main reason to choose one over the other, and it is the property most worth confirming rather than assuming from a supplier description.
What Should a Melanotan 1 Certificate Show?
The full thirteen residue sequence written out, with both terminal modifications.
Observed mass by spectrometry against the calculated 1646.8 for the free base, with the salt form stated separately.
Net peptide content, which is the fraction of the vial mass that is peptide rather than counterion and residual water.
Purity by chromatography with the gradient and column named.
Stereochemistry at position 7, since a purity percentage by area does not distinguish the D form from the L form when the two co-elute.
Absence of a sixteen dalton adduct, which on this sequence would mean oxidation somewhere other than the site engineered to avoid it.
Lot number and manufacturing date.
The stereochemistry line matters more here than on most articles, because both this molecule and its cyclic sibling depend on the same single D residue and a supplier producing both could plausibly mix a batch.
What Does the Longer Sequence Cost?
Keeping all thirteen residues costs melanotan 1 something the truncated sibling does not pay, and it shows up in three places.
The first is synthesis. Thirteen residues is a longer assembly than seven, which means more coupling steps and more opportunity for deletion sequences that differ from the target by a single residue.
Deletion impurities are the hardest kind to see, because a peptide missing one residue is chemically similar to the intended one and can elute very close to it.
The second is proteolytic exposure. A linear chain presents its backbone to peptidases along its whole length, and the D residue protects one position rather than all of them.
The third is the tyrosine and tryptophan content. Both are present here and both are photosensitive, with tryptophan the more so, which makes light protection a real requirement rather than a precaution.
None of these is a defect. They are the cost side of keeping the full parent sequence, and the gain side is the receptor selectivity that the truncated cyclic analogue gives up.
That trade is what separates the two compounds.
How Should the Vial Be Handled?
Melanotan 1 is a linear thirteen residue peptide with aromatic residues and no free cysteine, which makes it straightforward to store and easy to degrade through carelessness.
Sealed lyophilized powder holds at minus 20 degrees Celsius for extended periods and at 2 to 8 degrees for short ones, protected from light throughout.
Light protection is the instruction most worth taking seriously here. The tryptophan and the tyrosine both absorb, and photodegradation of tryptophan is well documented and produces species that are not obvious on a routine chromatogram.
Amber vials or foil are worth the effort on any solution held more than a few hours.
Bring the vial to ambient temperature before opening, since the powder is hygroscopic.
Reconstitute gently, adding diluent down the wall and letting it stand.
Aliquot on first reconstitution. A linear peptide of this length has more to lose from repeated freeze and thaw cycles than a small cyclic one does.
Use low-binding consumables. The arginine and the lysine both carry positive charge at neutral pH, so untreated glass takes material out of dilute solution.
Record lot, salt form, net peptide content, diluent, storage temperature, light protection and date.
Light protection belongs in the record here rather than being assumed, because it is a variable that differs between laboratories and it is one of the few that can quietly change a result.
A closing note on the melanotan 1 and melanotan 2 pairing, since a laboratory holding both will be storing them side by side.
The two are not interchangeable and they do not degrade the same way.
The cyclic sibling has no aromatic residue inside its ring beyond the tryptophan and is conformationally locked. This one is linear, longer and carries a tyrosine as well.
Storing them under one shared instruction gives the more fragile of the two the protection written for the sturdier one.
Published Literature
Selected references on the analogue programme that produced this molecule, on the controlled trial supporting the approved implant and on peptide storage generally.
- Al-Obeidi F, Castrucci AM, Hadley ME, Hruby VJ. Journal of Medicinal Chemistry. 1989;32(12):2555-2561. PMID: 2555512
- Hadley ME, Dorr RT. Peptides. 2006;27(4):921-930. DOI: 10.1016/j.peptides.2005.01.029
- Langendonk JG, Balwani M, Anderson KE, Bonkovsky HL, Anstey AV, Bissell DM, et al. New England Journal of Medicine. 2015;373(1):48-59. DOI: 10.1056/NEJMoa1411481
- Manning MC, Chou DK, Murphy BM, Payne RW, Katayama DS. Pharmaceutical Research. 2010;27(4):544-575. DOI: 10.1007/s11095-009-0045-6
Frequently Asked Questions
What is melanotan 1?
A linear thirteen residue analogue of alpha-melanocyte stimulating hormone, also called afamelanotide, carrying CAS 75921-69-6 and calculating to approximately 1646.8 daltons.
Does it hold a regulatory approval?
Yes, under the name afamelanotide. European authorisation came in 2014 and United States approval in October 2019, for a rare inherited condition affecting light tolerance.
What article was approved?
A 16 milligram bioresorbable subcutaneous implant releasing over an extended period. The approval attaches to that manufactured article rather than to the molecule itself, which is the distinction that matters.
Is a vial of powder the approved article?
No. It shares a molecule and nothing else. There is no controlled release element, no established release rate and no manufacturing dossier behind a research vial.
Why does the dosage form change the data?
A controlled release implant produces a low sustained level. A dissolved bolus produces a sharp peak. Receptor systems respond to the shape of exposure, not only to the total.
Does that matter for melanocortin receptors specifically?
It does. They are G protein-coupled receptors subject to desensitisation and internalisation on sustained engagement, so sustained and intermittent exposure can differ at equal integrated totals.
How does it differ from melanotan 2?
This one keeps all thirteen residues and stays linear. The sibling keeps seven of them and closes those seven into a ring. Both share the norleucine and D-phenylalanine substitutions.
Which is more receptor selective?
This one. It is described as selective for the melanocortin 1 receptor, while the cyclic sibling engages the family more broadly.
What does the longer sequence cost?
More coupling steps in synthesis and therefore more scope for deletion impurities, greater proteolytic exposure along a linear backbone, and two photosensitive aromatic residues.
Why are deletion impurities hard to detect?
Because a peptide missing one residue is chemically similar to the intended one. A routine gradient may not resolve the two.
What should the certificate confirm?
The full sequence with both terminal modifications, observed mass against 1646.8, net peptide content, purity with the method named, and stereochemistry at position 7.
Why does light protection matter here?
Both tryptophan and tyrosine are present and both absorb. Tryptophan photodegradation is well documented and produces species that are not obvious on a routine chromatogram.
Compliance Statement
Melanotan 1 is sold exclusively for laboratory research use. It is not a drug, food, or cosmetic product, and it is not a dietary product of any kind. It is not approved by the FDA or any comparable authority for human or veterinary use, the regulatory approval held under the name afamelanotide covers a bioresorbable implant for a specific rare indication and does not extend to lyophilized powder supplied for laboratory use, the controlled human data was generated with that implant and describes an exposure profile a dissolved preparation does not reproduce, the vial mass includes counterion and is not equivalent to peptide mass, and no compound in this range is offered for any human or veterinary purpose. This product is not intended to diagnose, treat, cure, or prevent any disease. It must not be given to humans or animals. Purchase is restricted to qualified researchers and institutions operating within applicable laws. All handling is the responsibility of the purchasing laboratory.
Other formats of MT-1
MT-1 is also stocked as Melanotan II 10mg Nasal Spray, Melanotan 2 10mg preloaded 3ml pen and MT-2 (Melanotan 2 Acetate) 10mg. Each listing states its own quantity and concentration, and the pen and vial comparison explains what changes between formats.
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