Melanotan-2 complete guide

Melanotan-2 (MT-2) is a cyclic 7-amino-acid synthetic peptide based on the structural template of alpha-melanocyte-stimulating hormone (alpha-MSH) — the 13-amino-acid pituitary hormone derived from proopiomelanocortin (POMC). The compound was originally synthesized in the 1980s by the Hruby laboratory at the University of Arizona during a research programme aimed at producing more stable, more potent melanocortin-receptor agonists for laboratory study. The structural design — truncating the parent alpha-MSH sequence to seven residues, replacing methionine with norleucine to resist oxidation, and cyclizing via a lactam bridge between Asp(5) and Lys(10) — produced a compound with a substantially extended biological half-life relative to native alpha-MSH and broad-spectrum agonism across the melanocortin-receptor family (MC1R, MC3R, MC4R and MC5R; the MC2R adrenocorticotropic-hormone receptor is unaffected).

This positions MT-2 as the most-studied broad-spectrum melanocortin-receptor agonist in the published research literature. Distinct research lines investigate melanin synthesis (via MC1R on melanocytes), appetite regulation (via central MC4R, the same receptor lineage that produced bremelanotide / PT-141 research), exocrine-gland and immune effects (via MC5R), and broader melanocortin-system biology. MT-2 is research-grade only. It is not approved as a tanning agent, not approved as a sexual-function therapy, and not approved for any human use in any jurisdiction. The widespread informal non-research use that exists outside the laboratory is not the subject of this article and is not endorsed in any way. This guide documents what the published peer-reviewed research has investigated, in mechanism-focused, research-frame language only.

Quick reference — Melanotan-2 identifiers

Property	Melanotan-2 (MT-2)
Class	Cyclic synthetic alpha-MSH analog; broad-spectrum melanocortin-receptor agonist
Sequence	Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 — 7 amino acids, lactam-cyclized between Asp(5) and Lys(10)
Molecular formula	C50H69N15O9
Molecular weight	1024.18 g/mol
CAS	121062-08-6
Origin	Synthetic; first reported by the Hruby laboratory (University of Arizona) in the 1980s as part of a structure–activity programme on melanocortin-receptor agonists
Plasma half-life	Research models: extended relative to native alpha-MSH (whose half-life is on the order of minutes), enabled by cyclization and the Met→Nle substitution
Receptor activity	Agonist at MC1R, MC3R, MC4R and MC5R with varying affinities; MC2R (the ACTH receptor) is unaffected
Vial strengths (TogoPeptide)	10 mg lyophilized — for laboratory research only

Origin and structure — cyclic alpha-MSH analog

Alpha-melanocyte-stimulating hormone (alpha-MSH) is a 13-amino-acid peptide — Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH2 — derived from proteolytic cleavage of proopiomelanocortin (POMC) in the pituitary and elsewhere in the central nervous system. Endogenous alpha-MSH binds the melanocortin-receptor family (MC1R–MC5R) with varying affinities and has the classical role in melanin and pigment regulation, alongside broader effects on appetite, immune modulation, sexual function, and cardiovascular regulation documented across the published melanocortin-research literature [6]. Native alpha-MSH has a short plasma half-life on the order of minutes, which limits its utility as a research probe in vivo.

The Hruby laboratory’s 1980s structure–activity programme tackled this stability problem directly. The first major output was NDP-MSH ([Nle4, D-Phe7]-alpha-MSH) — a linear 13-residue analog with the Met→Nle substitution and a D-phenylalanine swap at position 7, reported as a “highly potent alpha-melanotropin with ultralong biological activity” [1]. Subsequent work compressed the active core: truncating to seven residues, retaining the Nle and D-Phe substitutions, and cyclizing via a lactam bridge between Asp(5) and Lys(10). The resulting compound — Melanotan-2 — combined the resistance to degradation of NDP-MSH with the conformational rigidity of a macrocycle and an extended half-life suitable for in-vivo research designs [2].

It is worth distinguishing MT-2 from its structural cousins in the melanocortin-research family. Melanotan-1 (afamelanotide) is a linear 13-residue alpha-MSH analog — structurally closer to NDP-MSH than to MT-2 — and has been approved by FDA and EMA under the brand name Scenesse for the treatment of erythropoietic protoporphyria (a separate regulatory path with a defined clinical indication). Bremelanotide (PT-141) is a different cyclic 7-residue alpha-MSH analog with greater MC4R selectivity, FDA-approved as Vyleesi for hypoactive sexual desire disorder. MT-2 itself is not approved in any jurisdiction. Three structurally related melanocortin-research compounds, three different selectivities, three different regulatory paths.

Mechanism — broad-spectrum melanocortin agonism

MT-2's published research footprint is shaped by the fact that it engages four of the five melanocortin receptors. Each subtype has its own tissue distribution and downstream biology, and the broad-spectrum profile means that any in-vivo MT-2 outcome can in principle be driven by signaling at multiple MC receptors simultaneously.

MC1R activation — melanin-synthesis research

MC1R is the melanocortin receptor expressed on melanocytes. Published research documents MT-2 binding MC1R, activating adenylyl cyclase, raising intracellular cAMP, and engaging the PKA/MITF/tyrosinase axis that drives eumelanin synthesis. In research-animal models, MT-2 administration is documented to increase melanin density in skin and other pigmented tissues. This is the most well-replicated MT-2 research line and the one that, historically, brought the compound public attention beyond the research community.

MC4R activation — appetite and sexual-function research

MC4R is the central appetite-regulator in the melanocortin family. Loss-of-function mutations in MC4R are the most common known cause of monogenic obesity in humans, which establishes the receptor as a primary node in central energy-balance biology. Published MT-2 research documents MC4R-mediated appetite suppression in research-animal models. MC4R also mediates the sexual-function effects observed in some published melanocortin research [3] — the same receptor lineage that produced bremelanotide (PT-141), the more MC4R-selective cyclic alpha-MSH analog approved as Vyleesi.

MC5R activation — exocrine-gland research

MC5R is expressed on a range of exocrine tissues including sebaceous and lacrimal glands. Published research documents MT-2 effects on exocrine-gland function via MC5R, alongside contributions to immune-cell modulation in some research designs. The MC5R research line is smaller than the MC1R or MC4R lines but is mechanistically consistent with the broader melanocortin biology described in the Annual Review-class literature on the melanocortin system.

MC3R activation — appetite and inflammation crossover

MC3R is co-expressed with MC4R in central appetite circuits and contributes to MT-2's broader appetite-modulating profile. Published research also documents anti-inflammatory effects mediated through MC3R (and MC1R / MC5R), overlapping mechanistically with the wider published literature on melanocortin-derived anti-inflammatory peptides [4]. This is the same broader mechanism class that includes the alpha-MSH C-terminal tripeptide KPV.

Melanin-synthesis research literature

The melanin-synthesis line is the most well-replicated published MT-2 research direction. Across research-animal models, MT-2 administration is documented to increase melanin density in skin tissue, modify hair-follicle pigmentation, and engage the broader pigmentary biology defined by MC1R activation. Published structure–activity work places MT-2 alongside NDP-MSH as one of the two reference superpotent alpha-MSH analogs against which subsequent melanocortin-research compounds are compared [1]. The Hadley/Dorr review literature provides the canonical historical overview of this research line and its commercialisation context [6].

Critically, the documented melanin-synthesis effects in research-animal models are not a clinical claim and are not an endorsement of MT-2 as a tanning agent. The published research is research; the regulatory status is unchanged. MT-2 is not an approved tanning product in any jurisdiction.

Appetite and metabolic research

The MC4R-mediated appetite line is the second major published MT-2 research direction. Research-animal-model literature documents reductions in food intake and body-weight changes after MT-2 administration, consistent with the established role of MC4R as a central appetite-suppressor receptor [5]. Cone’s Anatomy and regulation of the central melanocortin system review remains the canonical reference for the wider MC4R-and-energy-balance neurobiology that frames this MT-2 research line.

As with the melanin-synthesis literature, this is research-model output. It is not a therapeutic claim, not a weight-loss endorsement, and not a basis for non-research use of MT-2.

MT-2 vs MT-1 (afamelanotide) vs PT-141 (bremelanotide)

Three melanocortin-research compounds with shared structural ancestry but different selectivities and different regulatory paths:

Compound	Structure	Receptor selectivity	Research / regulatory status
MT-1 (afamelanotide)	Linear 13-aa alpha-MSH analog	Broad MC	FDA / EMA approved (Scenesse) for erythropoietic protoporphyria
MT-2	Cyclic 7-aa alpha-MSH analog	Broad MC (MC1R–MC5R)	Research only — not approved in any jurisdiction
PT-141 (bremelanotide)	Cyclic 7-aa alpha-MSH analog, Asp-substituted	More MC4R-selective	FDA approved (Vyleesi) for hypoactive sexual desire disorder

How to read the table: three structurally related cyclic and linear alpha-MSH analogs, three different MC-subtype profiles, three different regulatory positions. MT-2 occupies the research-only, broad-spectrum agonist position. The two adjacent compounds (one linear, one cyclic and more MC4R-biased) have defined therapeutic indications and regulatory approvals; MT-2 itself does not.

Cardiovascular and immune research

Smaller published MT-2 research lines document effects on cardiovascular reflexes via MC5R and MC3R signaling, and on immune-cell modulation via MC1R / MC3R / MC5R. Published research suggests MT-2 has measurable anti-inflammatory effects in research models, mechanistically overlapping with the broader melanocortin-anti-inflammatory literature that includes alpha-MSH itself and its derived fragments [4]. These corpora are smaller than the melanin-synthesis or MC4R-appetite literatures but contribute to the broader picture of MT-2 as a broad-spectrum melanocortin-system probe rather than a single-axis tool.

Storage and handling

Melanotan-2 ships as lyophilized powder. Standard research-handling practice documented in the published literature on cyclic melanocortin peptides:

• Lyophilized state: sealed at −20°C, protected from light. Stable for the manufacturer-stated window (typically 24+ months).
• Diluent: bacteriostatic water (0.9% benzyl alcohol) is the standard reconstitution diluent for cyclic peptides of this class.
• Reconstituted state: refrigerate at 2–8°C. Use within ~28 days under refrigeration.
• Avoid freeze-thaw cycles after reconstitution.

Each TogoPeptide MT-2 shipment includes a per-batch Certificate of Analysis with HPLC purity (target ≥98%), mass-spectrometry identity confirmation, lot number, manufacture date, analysis date. See how to read a COA or reconstitution methodology for the methodology details.

Cross-research lines and pairings

• KPV pairing context: KPV is the alpha-MSH C-terminal tripeptide (Lys-Pro-Val), derived from the same parent hormone as MT-2 but acting through an entirely different mechanism class — intracellular NF-κB modulation rather than melanocortin-receptor agonism. The two compounds share parental ancestry but research-application context, not mechanism. See the KPV complete guide for the full alpha-MSH-fragment mechanism walk-through.
• Reconstitution math: documented in the reconstitution calculator for the 10 mg vial strength.
• Skin-research category: the wider MT-2 research line sits alongside the broader skin-and-pigment research compounds in the skin category.

Closing

Melanotan-2 is a cyclic 7-amino-acid synthetic analog of alpha-MSH and the most-studied broad-spectrum melanocortin-receptor agonist in the published research literature. Its structural design — truncation, Met→Nle substitution, and Asp(5)–Lys(10) lactam cyclization — produced a compound with extended biological half-life and agonist activity at MC1R, MC3R, MC4R and MC5R. The dominant published research lines are in melanin synthesis (MC1R), central appetite regulation (MC4R), and broader melanocortin-system biology (MC3R / MC5R, including exocrine-gland and immune effects).

This guide documents what published peer-reviewed research has investigated. It is mechanism context for laboratory researchers, not therapeutic recommendation, not protocol guidance, not a tanning-agent endorsement, and not a basis for self-administration of any kind. Melanotan-2 is research-grade only. It is not approved as a tanning agent, not approved as a sexual-function therapy, and not approved for any human use in any jurisdiction. The widespread informal non-research use that exists outside the laboratory is not the subject of this article and is not endorsed in any way.

Source Melanotan-2 for laboratory research:

• Melanotan-2 product page — full identifiers, 10 mg lyophilized vial, per-batch COA
• Skin-research compounds — full category listing
• KPV complete guide — the alpha-MSH C-terminal tripeptide, different mechanism class, same parent hormone

For methodology and laboratory-handling questions, contact our research-supply team at info@togopeptide.com.