Melanotan I

Melanotan 1 is the synthetic linear tridecapeptide [Nle⁴, D-Phe⁷]-alpha-MSH, also catalogued as afamelanotide and NDP-alpha-MSH. Sawyer and colleagues described it in 1980 as a highly potent alpha-melanotropin with ultralong activity. It is sold here as a 10mg lyophilised powder for in-vitro research only.

Two substitutions across thirteen residues. Norleucine replaces methionine at position 4, removing the most oxidation-prone side chain. L-phenylalanine at position 7 becomes D-phenylalanine, inside the His-Phe-Arg-Trp core. Sawyer et al. (1980) found the analogue resisted serum enzymes and was 26 times as potent as alpha-MSH in an adenylate cyclase assay.

Not strictly. It is a full agonist at MC1R, MC3R, MC4R and MC5R, with MC1R affinity roughly an order of magnitude higher than the other three and no activity at MC2R. The accurate term is MC1R-preferring. Researchers who need true subtype discrimination use purpose-built selective ligands.

They are different compounds with different CAS numbers. Melanotan 1 is a linear 13 residue analogue of full-length alpha-MSH (1646.9 g/mol, CAS 75921-69-6). Melanotan II is a cyclic 7 residue lactam built on the alpha-MSH 4-10 fragment (1024.2 g/mol, CAS 121062-08-6). The linear molecule keeps its MC1R preference, while cyclisation flattens activity across MC1R, MC3R, MC4R and MC5R.

Molecular formula C₇₈H₁₁₁N₂₁O₁₉, molecular weight 1646.9 g/mol, CAS 75921-69-6. The sequence is Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH₂, with an N-terminal acetyl group and a C-terminal amide. Mass spectrometry on batch UKPL-326 found [M+H]+ at 1647.9 m/z, matching that weight.

No. Afamelanotide is the active ingredient of Scenesse, an FDA-approved medicine, but the vial sold here is not a medicine. It holds no marketing authorisation from the MHRA and is not approved for human or veterinary use. It is supplied only as a reference material for in-vitro laboratory research.

Its radioiodinated form, ¹²⁵I-NDP-alpha-MSH, became the standard displacement radioligand for the melanocortin receptor family. Many published binding constants for melanocortin ligands are reported as inhibition of ¹²⁵I-NDP-alpha-MSH binding to cells expressing one receptor subtype. The unlabelled peptide serves as a full-agonist reference in cAMP assays.

Tryptophan at position 9 is photolabile and oxidises readily. The oxidation products appear as extra RP-HPLC peaks and lower the concentration of intact peptide. Norleucine at position 4 has already removed the methionine that native alpha-MSH would lose to oxidation. Keep sealed vials at -20°C in the dark and reconstitute away from direct sunlight and fluorescent light.

Yes. Batch UKPL-326 tested at 99.553% purity by HPLC against a ≥98.0% specification, with identity confirmed by mass spectrometry. Measured content was 10.23mg against 10mg declared. The certificate is published in the certificate section so you can check it before ordering.

You can buy Melanotan 1 in the UK only as an analytical reference material for in-vitro laboratory research. The vial sold here is not a licensed medicine and is not approved for human or veterinary use. Buyers must be 18 or over and confirm research-only use at checkout.

UK Peptide Lab sells Melanotan I 10mg online as a lyophilised powder, dispatched from the UK. The current batch, UKPL-326, has a third-party certificate covering purity, identity and content. Orders placed before 3pm on a working day are dispatched the same day, with free UK delivery over £69.

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.

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.