Melanotan 2 is a synthetic cyclic heptapeptide studied in research as a nonselective agonist of the melanocortin receptor family. It is catalogued under CAS number 121062-08-6 with a molecular formula of C₅₀H₆₉N₁₅O₉ and a molecular weight of 1024.18 g/mol (free base). The compound was designed as a more metabolically stable, receptor-active analog of alpha-melanocyte-stimulating hormone (alpha-MSH), the endogenous ligand that governs melanocortin receptor signaling. It is supplied as a lyophilized powder for laboratory research and is intended solely for research purposes, not for human use.
Within melanocortin receptor research, Melanotan 2 occupies a distinctive position because it activates multiple receptor subtypes rather than a single one. Where later-generation analogs were engineered for receptor selectivity, Melanotan 2's broad activity profile across MC1R, MC3R, MC4R, and MC5R makes it a widely referenced tool compound for probing the melanocortin system as a whole, and a frequent baseline against which selective analogs are compared in the published literature.
What is the molecular structure of Melanotan 2?
Melanotan 2 has a molecular weight of 1024.18 g/mol (free base) and the molecular formula C₅₀H₆₉N₁₅O₉. Structurally, it is a cyclic heptapeptide built around the core recognition sequence of alpha-MSH, modified to close a lactam ring between two side chains. The cyclization — formed between an aspartic acid residue and a lysine residue — locks the peptide backbone into a constrained conformation that published structure-activity studies associate with increased resistance to proteolytic degradation relative to the linear parent hormone.
The sequence also carries an N-terminal acetyl cap and a C-terminal amide, both structural features shared with native alpha-MSH that are documented as contributing to receptor-binding affinity. A D-phenylalanine substitution at one position — replacing the L-phenylalanine found in the native hormone — is a further modification described in the literature as increasing metabolic stability without eliminating melanocortin receptor activity. The research-grade material is characterized to a purity specification of ≥99.0% by HPLC, and the lyophilized form is a white to off-white powder.
What is the relationship between Melanotan 2 and alpha-MSH?
Endogenous alpha-MSH is a 13-amino-acid peptide derived from proteolytic processing of the precursor protein proopiomelanocortin (POMC). It is the primary endogenous agonist of the melanocortin receptors and is studied for its role in a range of physiological processes tied to those receptors, most notably pigmentation signaling through MC1R. Melanotan 2 was developed as a cyclic, truncated analog that retains the core melanocortin receptor-binding pharmacophore of alpha-MSH in a smaller, conformationally restricted scaffold.
This design lineage matters for research interpretation. Because Melanotan 2 is not a full-length copy of alpha-MSH but a synthetic analog built around its receptor-recognition core, research that references Melanotan 2 is examining melanocortin receptor agonism broadly rather than the complete biological profile of native alpha-MSH, which also involves processing and secretion dynamics unique to the endogenous hormone. Distinguishing the analog from the parent hormone is a standard methodological point in published melanocortin pharmacology literature.
What receptor pharmacology does published research describe for Melanotan 2?
Melanotan 2 is characterized in the literature as a nonselective melanocortin receptor agonist, with documented binding and activation across four of the five known receptor subtypes: MC1R, MC3R, MC4R, and MC5R. Each subtype is a class A G-protein-coupled receptor that couples primarily to Gs protein, activating adenylyl cyclase and elevating intracellular cyclic AMP upon ligand binding — the shared signaling architecture across the melanocortin receptor family.
The four subtypes are studied in distinct physiological contexts. MC1R is expressed on melanocytes and is the receptor most closely tied to pigmentation research, where its activation is studied in relation to tyrosinase expression and eumelanin synthesis pathways in melanocyte cell culture models. MC3R and MC4R are expressed predominantly in the central nervous system, particularly hypothalamic circuits studied in the context of energy homeostasis and feeding-behavior research. MC5R is more broadly distributed and is studied in relation to exocrine gland function. Because Melanotan 2 engages all four receptors without subtype selectivity, published research using the compound as a pharmacological tool typically frames its effects as reflecting combined melanocortin pathway activation rather than a single-receptor mechanism, a distinction addressed further in comparative work on selective melanocortin analogs.
How is Melanotan 2 studied in pigmentation and energy-homeostasis research models?
In pigmentation research, Melanotan 2 is used in melanocyte cell culture systems to examine MC1R-driven signaling cascades, including cAMP accumulation, downstream microphthalmia-associated transcription factor (MITF) expression, and tyrosinase pathway activity associated with eumelanin production. This body of work sits within the broader published literature on melanocortin signaling and pigment cell biology, and Melanotan 2's nonselective activity profile makes it a useful comparator against MC1R-selective analogs in structure-activity studies.
In parallel, Melanotan 2 is studied in preclinical models of energy homeostasis because of its activity at MC3R and MC4R, receptors documented in the literature as central regulators of hypothalamic feeding circuits. Research in this domain focuses on receptor occupancy, downstream signaling cascades, and circuit-level effects observed in model systems, rather than on outcomes in isolation. Rodent models remain the standard preparation for this line of work because the hypothalamic circuitry involving MC3R and MC4R is a multi-neuron system that is difficult to reconstruct fully in cell culture; published research in this context typically measures receptor-level and circuit-level signaling markers rather than isolated single-cell readouts. Amino Foundry makes no therapeutic or outcome claims regarding Melanotan 2; it is studied solely for its receptor-pharmacology and signaling mechanisms in research settings.
How does Melanotan 2 compare to selective melanocortin analogs?
Melanotan 2's nonselective activity profile is often the point of contrast in published melanocortin pharmacology, since later analogs were specifically engineered to narrow receptor engagement. Afamelanotide, for instance, is described in the literature as a more MC1R-focused analog, developed to concentrate activity on the pigmentation-associated receptor while reducing engagement at MC3R and MC4R. Bremelanotide, by contrast, is characterized as retaining more balanced MC3R/MC4R activity while showing reduced potency at MC1R relative to Melanotan 2. Neither analog eliminates activity at the other subtypes entirely, but both represent documented efforts to shift the selectivity profile away from Melanotan 2's broader engagement.
This selectivity gradient is a useful research variable in its own right. Structure-activity studies that compare Melanotan 2 against these more selective analogs can help attribute an observed effect to a specific receptor subtype by examining which compounds reproduce the effect and which do not. Because Melanotan 2 sits at the nonselective end of this spectrum, it is frequently used as the reference compound establishing the ceiling of combined-receptor engagement against which subtype-selective analogs are benchmarked. Published comparative pharmacology in this space treats receptor selectivity, rather than potency alone, as the primary axis differentiating the melanocortin analog research field.
What is known about Melanotan 2's stability and handling in research?
Melanotan 2 is supplied as a lyophilized powder and stored at −20°C to preserve structural integrity. As a peptide, it is sensitive to oxidation, moisture, and repeated freeze-thaw cycling, all of which can degrade the compound outside of the storage conditions established for its production lot. Research handling practices that support reproducibility include maintaining cold storage, minimizing freeze-thaw exposure, and protecting the lyophilized material from ambient humidity.
Cold-chain handling during shipping protects the same structural integrity that cold storage preserves after arrival. Material characterized at ≥99.0% purity at manufacture can degrade under thermal stress in transit, which is why cold-chain packaging is standard practice for peptide compounds of this class. For more on this, see our guide on cold-chain shipping. This article does not provide reconstitution or preparation instructions; handling protocols are determined by the researcher according to experimental requirements and applicable regulations.
How does Amino Foundry source Melanotan 2?
Amino Foundry supplies Melanotan 2 as a research-grade compound held to a purity specification of ≥99.0% by HPLC, with mass spectrometry identity confirmation. Every order ships with a batch-specific Certificate of Analysis, and all shipments are cold-chain packaged as standard. For guidance on interpreting that documentation, see our article on how to read a Certificate of Analysis, and for more on purity standards generally, see peptide purity.
Researchers can review specifications, available sizes, and pricing on the Melanotan 2 product page, or browse the full catalog at all compounds. All material is intended for laboratory research use only.
This compound is a research chemical intended for laboratory and scientific research purposes only. It is not a drug, supplement, or food, and is not intended to diagnose, treat, cure, or prevent any disease. Amino Foundry does not sell products intended for human consumption. Researchers are responsible for compliance with all applicable local, state, and federal regulations.
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