Melanotan 2 (MT-2) Research Guide
Melanocortin research peptide
Melanotan 2 is a synthetic cyclic analogue of alpha-melanocyte-stimulating hormone (alpha-MSH) developed at the University of Arizona in the 1980s. It activates the melanocortin receptors MC1R, MC3R, MC4R, and MC5R, producing the broad melanocortin profile studied in pigmentation, energy homeostasis, and inflammation research.
Contents
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Cyclic heptapeptide Synthetic alpha-MSH analogue |
MC1-5 Pan-melanocortin agonist |
University of Arizona Developed late 1980s |
What is Melanotan 2 (MT-2)?
Melanotan 2 is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone. The cyclization (an amide bridge between aspartic acid and lysine residues) confers metabolic stability that the native linear alpha-MSH lacks, extending plasma half-life from minutes to hours.
MT-2 differs from MT-1 (afamelanotide) by being smaller (7 vs 13 amino acids) and broader in receptor activity. While MT-1 is more selective for MC1R (the receptor primarily responsible for pigmentation), MT-2 activates all five melanocortin receptors, producing effects that extend beyond pigmentation into energy homeostasis, sexual function, and inflammation research.
Aeternum Labs supplies MT-2 as a lyophilized powder verified to 99%+ purity by HPLC with mass spectrometry sequence confirmation. Each batch ships with a publicly published Certificate of Analysis tied to the lot number.
Mechanism of action
Melanocortin receptors are G-protein-coupled receptors that signal primarily through cAMP. MT-2 binding to these receptors activates adenylate cyclase, raising intracellular cAMP and triggering downstream effects specific to each receptor type and the tissues that express them.
MC1R activation in melanocytes drives eumelanin synthesis, producing the pigmentation effects MT-2 is most known for. MC4R activation in the hypothalamus reduces food intake and increases energy expenditure, while MC4R activity at other sites mediates sexual function effects observed in research. MC3R and MC5R have more diffuse roles in energy balance and exocrine function.
The pan-receptor profile of MT-2 means it captures effects across all melanocortin receptors simultaneously, which is useful for some research designs but produces more confounding effects than selective agonists when researchers want to isolate single-receptor outcomes.
Research history
MT-2 was developed at the University of Arizona by Mac Hadley and colleagues in the late 1980s as part of a program to synthesize stable melanocortin analogues for medical research. The original goal was development of safer alternatives to UV-based pigmentation induction.
Research through the 1990s and 2000s characterized the broad receptor profile and the resulting effects beyond pigmentation. The compound has not received FDA approval for any indication, though MT-1 (afamelanotide), the related but more selective analogue, has been approved for treatment of erythropoietic protoporphyria.
Most research on MT-2 today focuses on melanocortin receptor pharmacology, energy homeostasis, and inflammation, with pigmentation research as a secondary focus given the broader systemic effects.
Half-life and pharmacokinetics
MT-2 is administered subcutaneously in research, with plasma half-life of approximately 30-60 minutes after administration. The cyclic structure provides metabolic stability compared to linear alpha-MSH, which has a sub-minute half-life.
Tissue distribution favors skin (melanocytes), hypothalamus, and adrenal tissue — sites with high melanocortin receptor density. Effects on pigmentation accumulate over weeks of repeated administration as eumelanin synthesis proceeds in melanocytes.
Typical research doses
Research dose ranges in animal and limited human studies span approximately 0.25 mg to 2 mg per administration. Titration is commonly used to manage initial nausea and flushing that can occur with first exposures.
Frequency in research designs is typically daily during initial loading periods, transitioning to maintenance dosing 2-3 times weekly once target effects are achieved. The dose-response relationship varies across the multiple receptor systems MT-2 activates.
Compliance reminder
All dose ranges discussed are reported from peer-reviewed in vitro and animal research. They are not human-use dose recommendations.
Reconstitution protocol
Lyophilized peptides require reconstitution with a sterile solvent before any in vitro work. The standard solvent across virtually all research-peptide protocols is bacteriostatic water (sterile water with 0.9% benzyl alcohol), which prevents microbial growth across the typical four-week working window once a vial is opened.
Add the solvent slowly down the inside wall of the vial rather than directly onto the lyophilized cake. Swirl gently until the powder dissolves fully. Do not shake — agitation can denature peptide bonds and reduce assay potency. A clear, particle-free solution should result within thirty to sixty seconds.
Volume calculations are straightforward. For a 10 mg vial reconstituted with 2 mL of bacteriostatic water, each 0.1 mL of the resulting solution contains 0.5 mg of peptide. Researchers planning multi-week protocols should compute their volumes ahead of time and document the lot number against each preparation.
For MT-2, a 10 mg vial reconstituted with 2 mL of bacteriostatic water yields 5 mg/mL. Each 0.05 mL contains 0.25 mg (a common starting research dose), allowing fine titration across the typical dose range.
Storage and stability
Sealed lyophilized vials are stable at 0°F (−18°C) for up to twenty-four months in most research literature. Vials should be kept dry, light-protected, and away from temperature fluctuations. Avoid storing peptides in the freezer door, where each open-close cycle introduces thermal stress.
Once reconstituted, store the working solution at 36–46°F (2–8°C). Most lyophilized peptides remain stable in solution for twenty-eight days under refrigeration with bacteriostatic water as the diluent. For protocols longer than four weeks, reconstitute fresh batches as needed rather than extending a single working vial.
Repeated freeze-thaw cycles reduce peptide integrity. If long-term storage of a reconstituted sample is required, aliquot the solution into single-use volumes before freezing so each thaw uses a fresh aliquot.
Common stack pairings
MT-2 + KPV (melanocortin pathway research)
Both compounds engage the melanocortin system. KPV is the C-terminal anti-inflammatory fragment of alpha-MSH; MT-2 is a stable full-receptor agonist. The combination is researched for inflammation studies where pan-melanocortin activity is combined with the KPV anti-inflammatory mechanism.
How it compares
Compared to MT-1 (afamelanotide): MT-1 is more selective for MC1R and primarily produces pigmentation effects without the broader systemic activity of MT-2. MT-1 has FDA approval for erythropoietic protoporphyria; MT-2 does not have approval anywhere.
Compared to alpha-MSH (native): MT-2 has a much longer half-life and broader receptor profile than the native peptide, making it more practical for research that requires sustained melanocortin engagement.
From the Aeternum library
Melanotan 2 (MT-2)
- 99%+ purity verified by HPLC
- Mass spec sequence confirmation
- LAL endotoxin screening
- Full Certificate of Analysis published
- Lyophilized powder
Frequently asked questions
What is the difference between MT-1 and MT-2?
MT-1 (afamelanotide) is a 13-amino-acid linear analogue with relative selectivity for MC1R, primarily producing pigmentation effects. MT-2 is a 7-amino-acid cyclic analogue that activates all five melanocortin receptors, producing broader systemic effects in addition to pigmentation. MT-1 has FDA approval for erythropoietic protoporphyria; MT-2 does not.
Why does MT-2 produce more side effects than MT-1?
MT-2’s pan-melanocortin profile activates MC3R, MC4R, and MC5R in addition to MC1R. Effects on these other receptors (appetite suppression, blood pressure changes, sexual function effects) produce the broader response profile that makes MT-2 useful for research but also produces more pronounced systemic effects than MT-1.
What dose ranges are used in research?
Research dose ranges span 0.25 mg to 2 mg per administration. Titration starting at lower doses (0.25 mg) is commonly used to manage initial nausea and flushing. Frequency transitions from daily loading to 2-3 times weekly maintenance.
How does MT-2 stability compare to native alpha-MSH?
MT-2 is cyclic (an amide bridge between aspartic acid and lysine residues), which confers metabolic stability. Plasma half-life is 30-60 minutes for MT-2 versus sub-minute for native linear alpha-MSH. The stability is what makes MT-2 practical for research.
How is MT-2 stored?
Sealed lyophilized vials at 0°F (−18°C) for up to twenty-four months. Reconstituted working solution at 36–46°F (2–8°C) is stable for approximately twenty-eight days.
References
- Hadley ME, Hruby VJ, Jiang J, et al. (1989). Discovery and development of novel melanogenic drugs. View source
- Catania A, Lonati C, Sordi A, et al. (2010). The melanocortin system in control of inflammation. View source
- Wessells H, Levine N, Hadley ME, et al. (2000). Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II. View source
Reviewed by
The Aeternum Labs Research Team
Compounds, COAs, and protocol design
The Aeternum Labs research team verifies every batch in our library against published purity and identity standards. Articles in our research blog summarize publicly available scientific literature and are reviewed for accuracy by team members trained in peptide biochemistry and laboratory protocol design.
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Research Disclaimer. All compounds discussed in this article are sold by Aeternum Labs for in vitro laboratory research purposes only. They are not intended for human or animal consumption, diagnosis, treatment, or prevention of any disease or condition. Information presented is summarized from publicly available scientific literature and should not be construed as medical advice.