For in-vitro laboratory research use only. Not for human or veterinary use.
Melanotan I 10mg lyophilised research peptide vial, batch UKPL-326
Peptides

Melanotan I 10mg

99.553% RP-HPLC + ESI-MSJanoshikBatch UKPL-326

£19.99£2.00/mg

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For in-vitro laboratory research use only. Not for human or veterinary use.

Batch & documentation

Batch
UKPL-326
Purity
99.553%
Method
RP-HPLC + ESI-MS
Laboratory
Janoshik

Documentation for each item ships with your order. The batch number printed on your vial matches it.

Melanotan 1 (MT1, also known as afamelanotide) is a research peptide from the melanocortin family and one of the most widely studied analogues of α-MSH. It has a linear 13 amino acid structure, which is the main thing separating it from the cyclic Melanotan 2. It acts on all four melanocortin receptors, most strongly at MC1R. Supplied as a lyophilised powder with a batch-specific certificate of analysis carrying supplier-reported figures, independent verification pending. Research use only. Not a medicine and not authorised for human use in the UK.

What is Melanotan I ?

Melanotan I is also catalogued as Melanotan 1, MT1, afamelanotide and NDP-alpha-MSH, written in analogue notation as [Nle⁴, D-Phe⁷]-alpha-MSH. Peptaro supplies it as a 10mg lyophilised powder.

Sawyer, Hruby, Hadley and colleagues first reported it in the Proceedings of the National Academy of Sciences in 1980. Only two of its thirteen residues differ from native alpha-MSH. Norleucine replaces the oxidation-prone methionine at position 4. Phenylalanine 7, inside the His-Phe-Arg-Trp core that every melanocortin receptor recognises, is inverted to its D-form. The analogue resisted degradation by serum enzymes and was 26 times as potent as alpha-MSH in a mouse melanoma adenylate cyclase assay. There is no lactam bridge, so unlike Melanotan II the MT1 peptide is fully linear.

Melanotan I Research Applications

  • Radioligand : the radioiodinated form, ¹²⁵I-NDP-alpha-MSH, is the standard displacement radioligand for the melanocortin receptor family.
  • Reference agonist : the unlabelled peptide is a full-agonist reference in cAMP accumulation assays, since all five melanocortin receptors signal mainly through Gs.
  • Structural biology : Zhang et al. (Cell Res, 2021) resolved afamelanotide bound to full-length MC4R in complex with Gs, showing a binding mode shared by peptide agonists.
  • Receptor subtypes : Adan et al. (Eur J Pharmacol, 1999) included [Nle⁴, D-Phe⁷]-alpha-MSH among nine ligands characterised on cloned rat MC3 and MC4 receptors.

Melanotan 1 is also the linear benchmark against which cyclic analogues such as the Melanotan II series are compared. All of this is receptor-level work in transfected cells and recombinant complexes, not evidence of any effect in humans.

Melanotan 1 vs Melanotan II vs alpha-MSH

Native alpha-MSH is the 13 residue parent, Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH₂, with an all-L backbone that peptidases cleave readily. Melanotan 1 keeps all thirteen residues and changes two: Nle⁴ for Met⁴ and D-Phe⁷ for L-Phe⁷. Melanotan II is truncated to the alpha-MSH 4-10 fragment and cyclised by a lactam bridge between Asp5 and Lys10 (C₅₀H₆₉N₁₅O₉, 1024.2 g/mol, CAS 121062-08-6).

The receptor profiles differ. Curated affinity data place Melanotan 1 as a full agonist at four subtypes. It shows pIC₅₀ 10.0 at MC1R, pKi 8.9 at MC3R, pKi 8.5 to 8.8 at MC4R and pIC₅₀ 9.0 at MC5R, with no activity at MC2R. Cyclisation in Melanotan II flattens that profile across MC1R, MC3R, MC4R and MC5R. Melanotan II therefore serves as the non-selective positive control, and Melanotan 1 as the MC1R-weighted reference agonist.

Research Overview

Melanotan I, also written Melanotan 1 or MT1, is the linear tridecapeptide [Nle⁴, D-Phe⁷]-alpha-melanocyte-stimulating hormone, catalogued in the literature as afamelanotide and as NDP-alpha-MSH, sequence Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH₂ (C₇₈H₁₁₁N₂₁O₁₉, 1646.9 g/mol, CAS 75921-69-6). It was first reported by Sawyer, Hruby, Hadley and colleagues in the Proceedings of the National Academy of Sciences in 1980, and it departs from native human alpha-MSH at only two of thirteen positions: norleucine replaces the oxidation-prone methionine at position 4, and the phenylalanine at position 7 is inverted to its D-enantiomer. Chain length is unchanged, and unlike Melanotan II there is no lactam bridge, so the mt1 peptide remains fully linear. The D-Phe⁷ inversion sits inside the conserved His-Phe-Arg-Trp message tetrapeptide that every melanocortin receptor recognises, and it is the substitution responsible for the markedly prolonged receptor occupancy reported for this analogue relative to alpha-MSH, because inverting that stereocentre removes a favoured chymotrypsin-like cleavage point. Because the molecule is linear, MT-1 is frequently but imprecisely described as MC1R-selective. Curated affinity data instead describe a full agonist at four of the five human melanocortin receptors: reported pIC₅₀ 10.0 at MC1R, pKi 8.9 at MC3R, pKi 8.5 to 8.8 at MC4R, and pIC₅₀ 9.0 at MC5R, with no activity at MC2R, the adrenocorticotropin receptor, which is not engaged by alpha-MSH analogues of this class. MC1R affinity is therefore roughly an order of magnitude higher than at the other three subtypes, a preference rather than selectivity in the strict pharmacological sense. All five subtypes are class A G-protein-coupled receptors signalling principally through Gs and adenylyl cyclase to raise intracellular cAMP. The radioiodinated form of this molecule, ¹²⁵I-NDP-alpha-MSH, is the standard displacement radioligand for the whole receptor family, which is why it appears throughout melanocortin binding literature. Afamelanotide is authorised as a medicine in certain jurisdictions. The material supplied here is not a medicine, holds no UK marketing authorisation, and is supplied as lyophilised powder strictly for in-vitro laboratory research use only.

Storage and Reconstitution

Store the sealed 10mg vial at -20°C in the dark. Keep reconstituted solution refrigerated at 2-8°C in amber or foil-wrapped vessels. Tryptophan 9 oxidises readily, with tyrosine 2 and histidine 6 as secondary sites. Freeze-thaw cycles speed aggregation and oxidation, so freeze single-use aliquots.

Vials are sold on their own, without bacteriostatic water for mixing or other supplies.

How to reconstitute and handle

Let the vial reach room temperature. Run bacteriostatic water slowly down the inside wall of the vial and swirl gently until dissolved. Do not shake. Work away from direct sunlight and fluorescent light, because tryptophan 9 is photolabile. Label the vial with the reconstitution date.

  • Protect from light at all stages. Tryptophan at position 9 is the principal photolabile residue and oxidises readily, with tyrosine at position 2 and histidine at position 6 secondary sites of concern. Note that the norleucine substitution at position 4 has already removed the methionine thioether, so residual oxidation risk in this analogue is concentrated at tryptophan.
  • Aliquot into amber or foil-wrapped single-use vessels and avoid repeated freeze-thaw cycling. The molecule carries both a tryptophan and a tyrosine chromophore, so concentration can be verified by UV absorbance at 280 nm where assay design requires it.

For the full method, see the peptide reconstitution guide and the reconstitution calculator.

Research References

Published research on Melanotan I is indexed on PubMed. See our full UK buyer's guide for Melanotan I and UK buyer's guide for Melanotan I CoA.

Specifications

CAS number75921-69-6
Molecular formulaC₇₈H₁₁₁N₂₁O₁₉
Molecular weight1646.9 g/mol
SequenceAc-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH₂
FormLyophilised powder
AppearanceWhite lyophilised powder
Release specification≥98.0%
Storage-20°C lyophilised, 2-8°C reconstituted, protect from light

Laboratory handling

Store sealed lyophilised vials at −20 °C, protected from light and moisture. For preparation, aliquoting and storage of reconstituted stock, see the laboratory reconstitution guide and the concentration calculator.

Melanotan I: frequently asked questions

What is Melanotan 1 (MT1)?

Melanotan 1 is the synthetic linear tridecapeptide [Nle⁴, D-Phe⁷]-alpha-melanocyte-stimulating hormone, also catalogued as afamelanotide and as NDP-alpha-MSH, molecular formula C₇₈H₁₁₁N₂₁O₁₉, molecular weight 1646.9 g/mol, CAS 75921-69-6. It was first described by Sawyer, Hruby, Hadley and co-workers in the Proceedings of the National Academy of Sciences in 1980 as an alpha-melanotropin analogue with unusually prolonged receptor activity. It is supplied here as lyophilised powder for in-vitro laboratory research use only and is not a medicine.

How does the MT1 peptide differ from native alpha-MSH?

Two substitutions across thirteen residues. Norleucine replaces methionine at position 4, removing the thioether side chain that is the most oxidation-prone group in the native hormone, and L-phenylalanine at position 7 is inverted to D-phenylalanine. The second change is the pharmacologically important one: position 7 lies inside the conserved His-Phe-Arg-Trp message tetrapeptide, and the inverted stereocentre both stabilises the bioactive conformation of that core and eliminates a favoured chymotrypsin-like cleavage site, which is why the 1980 characterisation described the analogue as long acting relative to alpha-MSH.

Is Melanotan 1 selective for MC1R?

Not in the strict sense. Curated affinity data describe Melanotan 1 as a full agonist at four of the five human melanocortin receptors, with reported pIC₅₀ 10.0 at MC1R, pKi 8.9 at MC3R, pKi 8.5 to 8.8 at MC4R and pIC₅₀ 9.0 at MC5R, and no activity at MC2R, the adrenocorticotropin receptor. MC1R affinity is roughly an order of magnitude higher than at the other three subtypes, so the accurate description is MC1R-preferring rather than MC1R-selective. Researchers needing genuine subtype discrimination use purpose-built ligands rather than this analogue.

What is the difference between Melanotan 1 and Melanotan II?

They are distinct chemical entities with different CAS numbers and should never be treated as interchangeable in a protocol. Melanotan 1 is a linear 13-residue analogue of the full alpha-MSH sequence (C₇₈H₁₁₁N₂₁O₁₉, 1646.9 g/mol, CAS 75921-69-6). Melanotan II is a cyclic lactam 7-residue analogue built on the truncated alpha-MSH 4-10 fragment (C₅₀H₆₉N₁₅O₉, 1024.2 g/mol, CAS 121062-08-6), closed by a bridge between the Asp5 side-chain carboxyl and the Lys10 side-chain amine. The consequence is different receptor and stability behaviour: the linear molecule retains a clear order-of-magnitude preference for MC1R, whereas cyclisation flattens activity across MC1R, MC3R, MC4R and MC5R and increases resistance to proteolysis.

What is the molecular formula, CAS number and sequence of MT-1?

Molecular formula C₇₈H₁₁₁N₂₁O₁₉, molecular weight 1646.9 g/mol, CAS number 75921-69-6. The full sequence is Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH₂, written in analogue notation as [Nle⁴, D-Phe⁷]-alpha-MSH, with a C-terminal primary amide and an N-terminal acetyl group. This vial contains 10mg of lyophilised powder, batch UKPL-326, tested at 99.553% purity by HPLC with the certificate published on this page.

Is Melanotan 1 a licensed medicine in the UK?

No. Afamelanotide is authorised as a medicine in certain jurisdictions outside the UK, but the material supplied here is not a medicine, holds no marketing authorisation from the MHRA, and is not approved for human or veterinary administration in the UK. It is supplied solely as an analytical reference material for in-vitro laboratory research. Purchasers must be aged 18 or over and must confirm research-only use at checkout. No claim is made or implied regarding any effect in humans.

Why does MT1 appear so often in melanocortin receptor assays?

Because its radioiodinated form, ¹²⁵I-NDP-alpha-MSH, became the standard displacement radioligand for the entire human melanocortin receptor family. A very large proportion of published binding constants for melanocortin ligands, including those for cyclic analogues and for subtype-selective candidates, are expressed as inhibition of ¹²⁵I-NDP-alpha-MSH binding to membranes from cells stably expressing one receptor subtype. The unlabelled peptide is used alongside it as a full-agonist reference point in cAMP accumulation assays.

Why must Melanotan 1 be stored protected from light?

Because tryptophan at position 9 is photolabile and oxidises readily, producing degradation peaks that are resolvable by RP-HPLC and that reduce the effective concentration of intact peptide in an assay. Tyrosine at position 2 and histidine at position 6 are secondary sites of concern. The norleucine substitution at position 4 has already removed the methionine oxidation site present in native alpha-MSH, so tryptophan is the residue that governs shelf behaviour. Store lyophilised vials at -20°C in the dark, hold reconstituted solution at 2-8°C in amber or foil-wrapped vessels, and reconstitute away from direct sunlight and fluorescent lighting.

Has your Melanotan 1 10mg batch been independently tested?

Not yet. Batch UKPL-326 is listed at 99.553% purity by HPLC on a supplier-reported certificate of analysis, with identity stated by the supplier, and that certificate is published on this product page. Independent third-party verification of this batch is pending. For an alpha-MSH analogue the impurity worth watching is oxidised tryptophan, which resolves as a distinct RP-HPLC peak, so researchers repeating an assay after extended storage should re-check the chromatogram rather than assume the release figure still holds. Supplied for in-vitro laboratory research only.

Where can I buy Melanotan 1 (MT1) 10mg in the UK for research?

Peptaro sells Melanotan I 10mg online as a lyophilised powder, dispatched from the UK. The current batch, UKPL-326, has a published certificate of analysis with supplier-reported purity, identity and content figures, and independent third-party verification is pending. Orders placed before 3pm on a working day are dispatched the same day, with free tracked UK delivery on every order.

What is the mt1 peptide used for in research?

It is used in vitro as an MC1R-weighted full-agonist reference at the melanocortin receptors. Its radioiodinated form is the standard displacement radioligand for the receptor family. It is also the linear benchmark for cyclic analogues such as the Melanotan II series.

How does MT-1 differ from MT2 at the receptor level?

Melanotan 1 prefers MC1R, by roughly an order of magnitude over MC3R, MC4R and MC5R, with no activity at MC2R. Melanotan II loses most of that gradient through cyclisation. Neither is subtype-selective in the strict sense, and both are characterised in transfected cell systems.

Is Melanotan I for human use?

No. Peptaro supplies Melanotan I 10mg strictly for in-vitro laboratory research. It is not a medicine and is not for human or veterinary use, and we don't give usage advice.

How quickly is Melanotan I dispatched in the UK?

Orders placed by 3pm Monday to Friday (excluding bank holidays) are dispatched the same working day by Royal Mail Tracked 24. Delivery is free, tracked and cold-packed. The minimum order is £299.

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Documentation for each item ships with your order. For in-vitro laboratory research use only. Not for human or veterinary use.