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Skin & melanocortin research peptides

Melanotan I (MT1): lab dossier and sourcing

Linear α-MSH analogue (afamelanotide) that activates the melanocortin-1 receptor. Afamelanotide increases skin pigmentation and was approved as an implant for erythropoietic protoporphyria.

Skin & MelanocortinCAS 75921-69-6AfamelanotideMT-IUpdated 2026-11-09
Original illustration for Melanotan I (MT1) research notes: abstract molecular artwork in orange and teal
Original illustration by USA Peptide Vendors; artistic, not a structural model.

At a glance

Ac-Ser-Tyr-Ser-Nle-Glu-His-D-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2 (Nle and D-Phe are non-standard).

CAS number
75921-69-6
Molecular formula
C78H111N21O19
Molecular weight
1646.84 g/mol
PubChem CID
16197727

Verified 2026-11-09 against KEGG DRUG D10511 and PubChem CID 16197727. Values we couldn't verify are left out.

What the literature covers

Afamelanotide increases skin pigmentation and was approved as an implant for erythropoietic protoporphyria.

Proposed Melanotan I signaling

Evidence level: Clinical: phase 3 trials. All mechanism maps

Melanotan I mechanism diagramMC1R agonism on melanocytes increases eumelanin. Targets: MC1R. Response: Melanocyte activation → Eumelanin ↑. Effects reported: Skin pigmentation ↑, Pain-free light exposure ↑.Melanotan I mechanism mapMC1R agonism on melanocytes increases eumelaninMelanotan IafamelanotideMC1Rmelanocortin-1 receptor [1]Melanocyte activation[1]Eumelanin ↑[1]Skin pigmentation ↑[1]Pain-free light exposure ↑EPP patients [1]Evidence: Clinical: phase 3 trials. Numbers in brackets refer to the cited sources.usapeptidevendors.com · Research Use OnlyRECEPTORRESPONSEEFFECTS REPORTED
Trial results apply to the approved implant, not to research-catalog vials. Open SVG
  1. Langendonk JG et al. Afamelanotide for Erythropoietic Protoporphyria. N Engl J Med. 2015;373:48-59.

Before you order

  • Purgo sells it as “MT1”. Make sure the COA names the analyte, not just the store label.
  • Match the CAS number on the certificate to 75921-69-6.
  • Purgo's description calls MT1 a pineal hormone that regulates sleep, which describes melatonin, not melanotan. Its product data gives afamelanotide's CAS number. Confirm which analyte the COA names.

FAQ

What is Melanotan I (MT1)?

Linear α-MSH analogue (afamelanotide) that activates the melanocortin-1 receptor. Afamelanotide increases skin pigmentation and was approved as an implant for erythropoietic protoporphyria.

What are Melanotan I (MT1)'s CAS number and molecular weight?

CAS 75921-69-6, formula C78H111N21O19, 1646.84 g/mol, per KEGG DRUG D10511 and PubChem CID 16197727.

Where can US labs buy Melanotan I (MT1)?

Purgo Labs stocks it as “MT1”; code usapeptidevendors takes 25% off at checkout. This page also lists the best-documented second vendor from our 112-vendor directory.

Is research-grade Melanotan I (MT1) for human use?

No. Vendor material is sold for Research Use Only, not for human or veterinary use.