MT-2 (Melanotan II): What the Research Shows About the Melanocortin Analog

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MT-2 (Melanotan II) is a synthetic cyclic analog of α-melanocyte-stimulating hormone, studied as a non-selective melanocortin-receptor agonist. This guide summarizes what the published scientific literature has examined about MT-2, its molecular profile, and how it is handled in a research setting. It is written for researchers and is not medical guidance.

What is MT-2?

MT-2 (Melanotan II, CAS 121062-08-6, molecular formula C₅₀H₆₉N₁₅O₉, molar mass ≈ 1024.2 g/mol) is a synthetic cyclic lactam heptapeptide analog of α-MSH, with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂. It is supplied as a lyophilized powder for laboratory research.

Research-use note: MT-2 is a research chemical supplied strictly for laboratory research. It is not an approved drug, cosmetic, or supplement and is not for human or animal consumption. Findings below come from receptor-pharmacology, animal-model, and published clinical studies.

Evidence at a glance

Limited human data, unapproved

Melanotan II showed clear effects in small early human studies, then development was abandoned. Read the two columns below together, because this is the compound where that matters most.

Why researchers are interested

It is a potent, broad melanocortin agonist. That is exactly why it produces pigmentation without UV exposure, and also why its effects are hard to confine to one system. The same lack of receptor selectivity drives both the findings and the harms.

What the research found

• Tanning without UV exposureStimulates melanogenesis directly through melanocortin-1 receptors, independent of sun exposure
• Erectile responseInitiated erections in men with psychogenic erectile dysfunction (Wessells)
• Receptor activity mappedCore sequence and receptor selectivity characterised (Oosterom, 1999, and Tomassi)

Reported in the literature

• Nausea, facial flushing and spontaneous erections were common in the early human studies.
• Darkening, enlargement and proliferation of existing moles is widely described.
• The dermatology literature carries case reports of melanoma diagnosed in people using unregulated melanotan.
• Case reports also describe rhabdomyolysis and posterior reversible encephalopathy after unregulated use.
• No regulator has approved it. Development was discontinued rather than completed.

Findings are summarised from the sources listed under References on this page, and from approved product labelling where a compound has one. These are outcomes observed in published studies, not effects claimed for any person, and nothing here is a recommendation for human use.

How MT-2 works (the mechanism studied)

MT-2 is a cyclic analog within the melanocortin family, studied as a broadly non-selective agonist across the MC1R–MC5R receptor subtypes. The lactam bridge constrains the peptide into a conformation that resists enzymatic degradation, giving it greater laboratory stability than native α-MSH. Because the melanocortin receptors sit in different tissues and pathways, pigmentation at MC1R, energy balance at MC4R, receptor selectivity is the central question in most MT-2 structure–activity work.

What researchers have studied

The MT-2 literature spans receptor pharmacology, analog design, and human studies conducted in the 1990s and 2000s. The most frequently cited include:

• Receptor-selectivity research: Oosterom et al. (J Biol Chem, 1999) examined how the conformation of the core sequence in melanocortin peptides directs selectivity for the MC3 and MC4 receptors.
• Analog-design research: Tomassi et al. (J Med Chem, 2022) used Melanotan-II as a scaffold to generate functionally selective human melanocortin-receptor agonists.
• Human melanocortin research: Wessells et al. reported controlled studies of the compound in men, first as a double-blind placebo-controlled crossover trial (J Urol, 1998) and later in a review of melanocortin-receptor agonists and sexual motivation (Int J Impot Res, 2000).

These findings describe research outcomes in laboratory models, not validated outcomes in humans.

Handling and reconstitution in the laboratory

MT-2 is typically supplied as a lyophilized powder for research use. Standard laboratory practice is to reconstitute it with bacteriostatic water, swirl (not shake) until dissolved, and store the reconstituted solution refrigerated (2–8 °C). The lyophilized powder is generally stored frozen and protected from light. (General lab-handling notes, not usage instructions.)

For research use only

All products and information referenced here are intended strictly for laboratory and scientific research use only. They are not for human or animal consumption and are not drugs, foods, supplements, cosmetics, or medical devices. No statement here should be interpreted as medical advice.

Explore MT-2 and related research peptides

• MT-2 10mg: verified CAS, formula, and specifications
• PT-141 10mg, the other melanocortin-receptor agonist in the catalog
• Bacteriostatic Water 30ml, reconstitution diluent

References

1. Oosterom J, et al. Conformation of the core sequence in melanocortin peptides directs selectivity for the melanocortin MC3 and MC4 receptors. J Biol Chem. 1999. PubMed
2. Tomassi S, et al. CLIPSing Melanotan-II to discover multiple functionally selective hMCR agonists. J Med Chem. 2022. PubMed
3. Wessells H, et al. Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study. J Urol. 1998. PubMed
4. Wessells H, et al. Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II. Int J Impot Res. 2000. PubMed