Melanotan II (MT-2): Research Overview

Melanotan II is a compact, cyclic melanocortin analog widely used as a reference agonist in melanocortin-signaling research. This overview is for laboratory and educational reference only.

What is Melanotan II?

Melanotan II (MT-2) is a cyclic lactam analog of α-MSH (alpha-melanocyte-stimulating hormone), with CAS 121062-08-6 and a molecular weight of ~1024.2. Where native α-MSH is a linear 13-residue peptide, MT-2 is a truncated, cyclized structure in which a lactam bridge locks the molecule into a conformation that resists enzymatic degradation and increases potency in laboratory systems.¹ This cyclization is the defining structural feature that distinguishes MT-2 from the linear analog Melanotan I.

Conformational constraint is a well-established strategy in peptide chemistry: by holding the backbone in a fixed geometry, a cyclic analog reduces the entropic cost of receptor binding and limits the flexible sites where peptidases would otherwise cleave the molecule. The lactam-bridged [Nle⁴, D-Phe⁷] scaffold that MT-2 is built on was designed on exactly this principle — molecular-dynamics-guided cyclization to produce a potent, prolonged-acting melanotropin.¹ Because the constrained backbone is less exposed to proteolysis, its functional half-life in assay systems is longer than that of the native hormone, which is one reason MT-2 is frequently used as a reference melanocortin agonist in the laboratory rather than the shorter-lived native hormone.

Mechanism

The melanocortin system comprises five G-protein-coupled receptors — MC1R through MC5R — that couple to adenylate cyclase and elevate intracellular cAMP on activation. MT-2 is studied as a non-selective melanocortin agonist, meaning it engages MC1R, MC3R, MC4R, and MC5R rather than favoring one subtype.¹²

• MC1R is expressed on melanocytes and is the receptor most directly associated with melanogenesis research. Its activation by α-MSH is positively coupled to cAMP and drives the enzymatic program that shifts pigment synthesis toward eumelanin.³
• MC3R and MC4R are studied in the context of central signaling pathways. MC4R in particular is examined in feeding and energy-balance models, where melanocortin agonists reduce food intake.⁴⁵
• MC5R is examined in exocrine and peripheral-tissue models.

Because MT-2 activates the family broadly, it is used in research as a tool to probe melanocortin-receptor pharmacology, including studies that also examined signaling beyond pigmentation — for example MC4R-mediated pathways relevant to erectile physiology⁶ and to appetite and fat intake.⁴⁵ This non-selectivity is analytically useful: a single compound that engages the whole receptor family lets researchers survey melanocortin responses across tissues, then compare those results against subtype-selective tools such as the MC1R-preferring analog Melanotan I to isolate which effects track with which receptor. The trade-off is that non-selective activation makes MT-2 a blunt instrument for questions that require targeting a single subtype.

Research models

• Melanogenesis assays — melanocyte and cell-culture systems examining MC1R-driven pigment-pathway activation and the eumelanin/pheomelanin switch.³
• Melanocortin-signaling studies — receptor-binding and cAMP-response characterization across MC1R–MC5R.¹
• MC4R-mediated central models — studies in which MT-2 is used to probe feeding, appetitive behavior, and fat consumption through MC4R.⁴⁵
• Comparative analog work — side-by-side studies with linear α-MSH and with the MC1R-selective analog Melanotan I.
• Early pharmacology characterization — pilot work profiling MT-2's superpotent melanotropic activity relative to native α-MSH.²

All of these are laboratory and preclinical research contexts, not established uses. Renova provides Melanotan II strictly as a reference melanocortin agonist for this kind of characterization work, with no human application intended or implied. A closely related melanocortin peptide, PT-141 (bremelanotide), is derived from the same MT-2 scaffold and is studied separately as a more MC4R-directed tool.

How it's supplied

Melanotan II is supplied as a lyophilized powder, reconstituted with bacteriostatic water for laboratory use, and refrigerated at 2–8°C after reconstitution. Every lot ships with a per-batch third-party COA. See Understanding Peptide Reconstitution and How to Store Research Peptides.

Purity & verification

Renova Melanotan II is third-party tested, with identity and purity documented on a per-batch certificate of analysis (HPLC plus mass spectrometry, with endotoxin screening). See How to Read a Peptide COA and confirm any lot with Verify Your Vial. For the MC1R-selective linear analog, see Melanotan I.

What the research does not establish

MT-2's evidence base is a mix of peptide-chemistry characterization, receptor pharmacology in cell and animal systems, and small early-phase human pilot studies. Those human studies were dose-finding and mechanistic in scope — they do not establish safety, efficacy, or any approved use, and reported effects such as pigmentation change and erectile response are documented as pharmacological observations, not endorsements.²⁶ The non-selective receptor profile that makes MT-2 useful as a survey tool is also why it is a poor model for questions that require single-subtype specificity. Renova makes no cosmetic, tanning, sexual-function, weight, or therapeutic claims of any kind; the citations below are provided so researchers can consult the primary melanocortin literature directly.

References

Explore Melanotan II →

References

1. Al-Obeidi F, Castrucci AM, Hadley ME, Hruby VJ. Potent and prolonged acting cyclic lactam analogues of alpha-melanotropin: design based on molecular dynamics. J Med Chem. 1989;32(12):2555–2561. PMID: 2555512. ↩ ↩² ↩³ ↩⁴

2. Dorr RT, et al. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sci. 1996;58(20):1777–1784. PMID: 8637402. ↩ ↩² ↩³

3. García-Borrón JC, Sánchez-Laorden BL, Jiménez-Cervantes C. Melanocortin-1 receptor structure and functional regulation. Pigment Cell Res. 2005;18(6):393–410. PMID: 16280005. ↩ ↩²

4. Samama P, Rumennik L, Grippo JF. The melanocortin receptor MCR4 controls fat consumption. Regul Pept. 2003;113(1-3):85–88. PMID: 12686465. ↩ ↩² ↩³

5. Eliason NL, Martin L, Low MJ, Sharpe AL. Melanocortin receptor agonist melanotan-II microinjected in the nucleus accumbens decreases appetitive and consumptive responding for food. Neuropeptides. 2022;96:102289. PMID: 36155088. ↩ ↩² ↩³

6. Wessells H, et al. Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study. J Urol. 1998;160(2):389–393. PMID: 9679884. ↩ ↩²