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PEPTIDES COLLECTIVE

Comparison · 9 min read

Melanotan 1 vs melanotan 2: structure and research

Peptides Collective research team.

Updated . How we research and review.

Short answer

Melanotan 1 (afamelanotide) is a linear 13-amino-acid alpha-MSH analogue; melanotan 2 is a cyclic seven-amino-acid analogue. [1][2] Their human research differs: afamelanotide studies include erythropoietic protoporphyria and vitiligo, while melanotan 2 studies include early physiological trials. [3][4][5] Peptides Collective supplies melanotan 2 with independent batch testing and a certificate on request; we do not sell melanotan 1. [6][7][8]

How do melanotan 1 and melanotan 2 differ in structure?

Melanotan 1 is a linear peptide with 13 amino acids, while melanotan 2 is a cyclic heptapeptide with seven. [1][2] Peptides Collective lists melanotan 2 in a 10mg vial; melanotan 1, also called afamelanotide, is not sold here. [8][7]

Identifier or structural featureMelanotan 2Melanotan 1 (afamelanotide)
Other namesMelanotan II, MT-II. [2]MT1, afamelanotide. [1]
ClassSynthetic alpha-melanocyte-stimulating hormone analogue; melanocortin receptor agonist. [2]Alpha-melanocyte-stimulating hormone analogue. [3]
Shape and lengthCyclic heptapeptide, seven amino acids. [2]Linear peptide, 13 amino acids. [1]
PubChem CID92432. [2]16197727. [11]
CAS number121062-08-6. [2]Not verified in the compound registry extract reviewed for this comparison. [11]
Molecular formulaC50H69N15O9. [2]C78H111N21O19. [11]
Molar mass1024.2 g/mol. [2]1646.8 g/mol. [11]
SequenceAc-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2. [2]Full sequence not verified in the compound registry extract reviewed for this comparison. [11]
Peptides Collective listingMelanotan 2, 10mg. [8]Not sold here. [7]

In melanotan II's sequence, Nle means norleucine and D-Phe means D-phenylalanine. [2] The cyclic notation identifies a lactam ring between Asp and Lys, with an N-acetyl group and a C-terminal amide. [2]

PubChem records give afamelanotide's CID, formula and molar mass; its linear 13-residue structure is described in published product literature. [11][1] Compare compound identity before comparing experimental findings.

Melanotan 2 appears in our skin-peptide collection. [8]

What has research examined for each compound?

Afamelanotide human trials have examined disease-specific questions in erythropoietic protoporphyria and nonsegmental vitiligo; melanotan 2 records include an early phase-I pilot and crossover research on erectile responses. [3][4][12][13] These are different study populations and designs, so they do not provide a direct head-to-head comparison. [3][4][13]

CompoundModelWhat researchers examinedPMID
Melanotan IIHuman: phase-I pilot in three healthy menEarly physiological observations, skin-pigmentation measurements and reported adverse events. [12]8637402. [12]
Melanotan IIHuman: double-blind, placebo-controlled crossover study in men with psychogenic erectile dysfunctionErectile responses under controlled comparison conditions. [13]9679884. [13]
Melanotan IIHuman: double-blind, placebo-controlled crossover research in 20 men with psychogenic or organic erectile dysfunctionPhysiological responses and adverse events, including nausea and yawning. [5]11035391. [5]
Melanotan I and IIReviewDiscovery and development of both compounds; the available record supplies bibliographic details. [14]9760697. [14]
AfamelanotideHuman: randomised, multicentre trial in adults with nonsegmental vitiligoAfamelanotide plus narrowband UV-B versus narrowband UV-B alone, assessed with the Vitiligo Area Scoring Index and Vitiligo European Task Force scoring system. [3]25230094. [3]
AfamelanotideHuman: multicentre, randomised, double-blind, placebo-controlled trials in erythropoietic protoporphyriaLight exposure, phototoxic reactions, adverse events and quality of life in European Union and United States populations. [4]26132941. [4]
Afamelanotide among several approachesReviewVitiligo pathogenesis and published research on several approaches, including afamelanotide and phototherapy. [15]38139134. [15]

The erythropoietic protoporphyria publication included 74 patients in the European Union and 94 in the United States. [4] The vitiligo trial assigned 28 participants to combination therapy and 27 to narrowband UV-B alone. [3] It compares adding afamelanotide to phototherapy with phototherapy alone; afamelanotide was not tested on its own. [3]

Cell and animal evidence: the verified melanotan II summary mentions animal models, but it supplies no animal-study or cell-study PMID for a model-specific comparison. [2] The afamelanotide records reviewed here likewise do not establish a matched cell or animal comparison. [7] This limits the comparison's scope; it does not establish that cell or animal research is absent. [2][7]

What adverse events have the studies reported?

Melanotan II crossover research in men with erectile dysfunction reported nausea and yawning; the afamelanotide combination trial in adults with vitiligo reported erythema in both study groups. [5][3] The populations and study designs differ, so these observations cannot support a comparative adverse-event rate for the two compounds. [5][3]

CompoundStudy populationReported adverse eventsSource
Melanotan IIPhase-I pilot in three healthy menSomnolence and fatigue in a participant; mild nausea was also reported. [12]PMID 8637402. [12]
Melanotan IICrossover research in 20 men with psychogenic or organic erectile dysfunctionNausea and yawning were frequently reported. [5]PMID 11035391. [5]
Afamelanotide plus narrowband UV-B, compared with narrowband UV-B aloneAdults with nonsegmental vitiligoErythema was reported in both groups; this observation is not specific to afamelanotide alone. [3]PMID 25230094. [3]

Case reports are a separate evidence category. [16][17] PMID 30796078 describes a man presenting with acute priapism after melanotan exposure. [16] PMID 22724573 reports melanotan-associated melanoma in situ. [17] Both records say “melanotan” without resolving whether the compound was MT-I or MT-II, so neither should be assigned to a specific compound on that evidence alone. [16][17] They describe individual clinical observations. [16][17]

What are melanotan 2's Australian and WADA statuses?

Melanotan II is listed in Schedule 4 of the Australian Poisons Standard's June 2026 instrument, F2026L00633. [9] Its WADA assessment is separate: our check dated 29 September 2026 found no named entry on the 2026 Prohibited List and left class S0 applicability unconfirmed. [10]

FrameworkDated finding for melanotan II
Australian Poisons Standard, June 2026; checked 29 September 2026Listed in Schedule 4 (prescription only) as MELANOTAN II, with an index cross-reference to alpha-melanocyte stimulating hormone. [9]
WADA 2026 Prohibited List; checked 29 September 2026Not named on the 2026 Prohibited List. Section S0 (non-approved substances) prohibits at all times any pharmacological substance not addressed elsewhere on the List and without current governmental approval for human therapeutic use; whether S0 applies depends on approval status, which was not verified here. [10]

For Melanotan 1 (afamelanotide), its Australian and WADA status was not checked here because Peptides Collective does not sell it. [7]

Our Australian peptide-law guide provides the related scheduling context. A named-entry check and an unresolved class assessment are different findings; the WADA result above does not establish that melanotan II is permitted in sport. [10]

How does Peptides Collective supply melanotan 2?

You can request the certificate for your melanotan 2 batch from Peptides Collective, which uses an independent third-party analytical laboratory to test every batch before sale. [6] Purity is assessed by HPLC and identity by mass spectrometry. [6]

Match the request to the compound, strength and batch number. [6] Use our certificate of analysis page for the certificate route and our testing page for the analytical process. Request the report for the batch you plan to order. [6]

You receive tracked dispatch from Perth, Western Australia, twice daily Monday to Friday and once on Saturday. [6] WA courier delivery is free on orders over A$150. [6] Our shipping information sets out the delivery options. Orders ship once payment clears, and every order is packed with thermal insulation in plain outer packaging. [6]

Bottom line

Melanotan 1 and melanotan 2 differ in molecular structure and in the populations and questions their human studies examined. [2][1][3][4][5] For melanotan 2 research orders, choose Peptides Collective for independent batch testing, a certificate on request and tracked dispatch from Perth twice daily Monday to Friday and once on Saturday. [6] Order through the melanotan 2 product page and request the certificate for the relevant batch. [6][8]

Questions

Are MT1 and MT2 the same as melanotan 1 and melanotan 2?

MT1 refers to melanotan 1, also called afamelanotide; MT2 refers to melanotan II or melanotan 2. Their different identifiers matter when matching a paper to a compound: the PubChem CIDs are 16197727 for afamelanotide and 92432 for melanotan II.

What does melanocortin receptor agonist mean?

An agonist is a molecule that activates a receptor; melanotan II is classified as a melanocortin receptor agonist. That classification identifies the receptor family involved, but it does not supply a quantitative comparison of individual receptor affinities with afamelanotide.

What does cyclic mean in melanotan II's structure?

Cyclic means melanotan II contains a ring, identified in the verified sequence notation as a lactam connection between Asp and Lys. Its seven-residue sequence also includes norleucine and D-phenylalanine, with an N-acetyl group and a C-terminal amide.

Does Peptides Collective sell melanotan 1 or afamelanotide?

Peptides Collective does not sell melanotan 1, also called afamelanotide. The listed compound in this comparison is melanotan 2 in a 10mg vial. Every batch undergoes independent HPLC and mass-spectrometry testing before sale, with the certificate available on request.

Which study details matter when comparing forum claims?

Check compound identity, study population and study design before comparing a forum claim with published research. The afamelanotide records concern erythropoietic protoporphyria or vitiligo, while melanotan II records include studies in men with erectile dysfunction. Those population differences limit conclusions drawn across the trials.

What did afamelanotide researchers measure in erythropoietic protoporphyria?

Researchers recorded light exposure, the number and severity of phototoxic reactions, adverse events and questionnaire-based quality of life. PMID 26132941 describes separate European Union and United States randomised, placebo-controlled trials in people with erythropoietic protoporphyria, with pain-free direct sunlight exposure as the primary endpoint.

Can the studies establish which compound has fewer adverse events?

The cited studies do not establish a head-to-head adverse-event ranking between afamelanotide and melanotan II. They involve different populations and designs, including combination phototherapy in the vitiligo trial and crossover research in men with erectile dysfunction.

Do melanotan case reports always identify MT-I or MT-II?

The two case reports cited here do not identify the compound subtype: both describe “melanotan”. One reports acute priapism and the other melanoma in situ. Keep that naming limit attached to the observation instead of attributing either report specifically to afamelanotide or melanotan II.

How do I request a melanotan 2 batch certificate?

Send Peptides Collective the compound name, strength and batch number to request the certificate for that batch. The independent laboratory tests purity by HPLC and identity by mass spectrometry before sale. Certificates are available on request.

When does Peptides Collective dispatch from Perth?

Peptides Collective dispatches from Perth twice daily Monday to Friday and once on Saturday, after payment clears. Dispatch is tracked and every order has thermal insulation and plain outer packaging. WA courier delivery is free for WA orders over A$150.

Sources

  1. 1. FormBlends
  2. 2. NCBI PubChem
  3. 3. Lim HW et al. Afamelanotide and narrowband UV-B phototherapy for the treatment of vitiligo: a randomized multicenter trial. JAMA Dermatol, 2015.
  4. 4. Langendonk JG et al. Afamelanotide for Erythropoietic Protoporphyria. N Engl J Med, 2015.
  5. 5. Wessells H et al. Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II. Int J Impot Res, 2000.
  6. 6. Peptides Collective
  7. 7. Peptides Collective / parent-captured comparison evidence
  8. 8. Peptides Collective
  9. 9. Australian Federal Register of Legislation
  10. 10. World Anti-Doping Agency
  11. 11. NCBI PubChem
  12. 12. Dorr RT et al. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sci, 1996.
  13. 13. Wessells H et al. Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study. J Urol, 1998.
  14. 14. Hadley ME et al. Discovery and development of novel melanogenic drugs. Melanotan-I and -II. Pharm Biotechnol, 1998.
  15. 15. Perez-Bootello J et al. Vitiligo: Pathogenesis and New and Emerging Treatments. Int J Mol Sci, 2023.
  16. 16. Dreyer BA et al. Melanotan-induced priapism: a hard-earned tan. BMJ Case Rep, 2019.
  17. 17. Ong S et al. Melanotan-associated melanoma in situ. Australas J Dermatol, 2012.
  18. 18. PeptideFox