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Melanotan II: Melanocortin-Receptor Research Compound Overview

A research overview of the synthetic cyclic alpha-MSH analog Melanotan II, its non-selective melanocortin-receptor mechanism, and the pigmentary, metabolic, and receptor-pharmacology research domains it has been studied in.

Melanotan II
All content on this page is for laboratory and academic reference only. This compound is supplied under a Research Use Only framework for in vitro and preclinical investigation by qualified personnel. Nothing on this page is clinical guidance, and it should not be interpreted as instructions for use in humans or animals.

Key Takeaways

  • Melanotan II is a synthetic cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (alpha-MSH), engineered with a lactam bridge for greater potency and stability than the natural hormone.[1]
  • It acts as a non-selective agonist across melanocortin receptor subtypes MC1R, MC3R, MC4R, and MC5R, rather than targeting a single receptor.[1]
  • A pilot phase 1 clinical study reported dose-dependent skin pigmentation changes in human subjects.[1]
  • In rodent research models, Melanotan II administration was reported to reduce neuropeptide-Y-driven feeding and fat-storage effects without affecting NPY's suppressive effects on reproductive and growth hormone axes.[2]
  • Separately, a placebo-controlled human study reported Melanotan II initiating erections in men with psychogenic erectile dysfunction, research that subsequently informed development of the selective MC4R agonist bremelanotide.[3]

What It Is

Melanotan II is a synthetic cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (alpha-MSH), a naturally occurring peptide hormone involved in pigmentation and several other physiological processes. Melanotan II retains the core 4-10 melanocortin receptor-binding region shared by alpha-MSH and adrenocorticotropic hormone, but is engineered with a lactam bridge that confers greater potency and metabolic stability than the natural hormone.[1]

Mechanism & Pathway

Unlike receptor-selective compounds, Melanotan II is studied as a non-selective melanocortin-receptor agonist, activating MC1R, MC3R, MC4R, and MC5R subtypes rather than a single receptor target. This broad receptor activity is proposed to explain the range of effects reported across different research domains: MC1R activation is linked to pigmentation research, MC3R/MC4R activation to feeding and energy-balance research, and MC4R activation specifically to sexual-function research.[1] In rodent studies, intracerebroventricular administration of Melanotan II was reported to reduce the feeding-stimulating and fat-storage effects driven by neuropeptide Y (NPY), while leaving NPY's separate suppressive effects on reproductive and growth hormone axes unaffected — indicating pathway-specific rather than uniform interaction with NPY signaling.[2]

Research Domains

  • Pigmentation research — a pilot phase 1 clinical study reported dose-dependent skin darkening in human subjects following Melanotan II administration.[1]
  • Feeding & energy-balance research — rodent studies report Melanotan II reducing NPY-driven feeding and adipogenic effects via central melanocortin receptor activation.[2]
  • Sexual-function research — a placebo-controlled crossover study in men with psychogenic erectile dysfunction reported Melanotan II initiating erections, research that informed later development of the selective MC4R agonist bremelanotide.[3]
  • Dermatological & oncology research — topical Melanotan II application in melanoma cell research models has been studied in connection with PTEN pathway regulation.[4]

Comparative Notes

Melanotan II is mechanistically related to KPV, another alpha-MSH-derived research compound in this catalog, but the two are studied for opposite pharmacological properties: Melanotan II is a non-selective melanocortin-receptor agonist studied for its broad receptor-activating effects, while KPV is specifically studied for anti-inflammatory activity that is independent of melanocortin receptor binding. The two represent different research angles on the same parent hormone system.

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Certificate of Analysis: What to Look For

A Certificate of Analysis for a Melanotan II research vial should report, at minimum: confirmed amino acid sequence (typically via mass spectrometry) and net peptide content. Vials should be stored lyophilized at -20°C, protected from light, consistent with handling guidance for the other lyophilized peptides in this catalog.

References

  1. Dorr RT, Lines R, Levine N, Brooks C, Xiang L, Hruby VJ, Hadley ME (1996). Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sciences. PMID: 8637402
  2. Raposinho PD, White RB, Aubert ML (2003). The melanocortin agonist Melanotan-II reduces the orexigenic and adipogenic effects of neuropeptide Y (NPY) but does not affect the NPY-driven suppressive effects on the gonadotropic and somatotropic axes in the male rat. Journal of Neuroendocrinology. PMID: 12535159
  3. Wessells H, Fuciarelli K, Hansen J, Hadley ME, Hruby VJ, Dorr R, Levine N (1998). Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study. Journal of Urology. PMID: 9679884
  4. Wu JC, Tsai HE, Hsiao YH, Wu JS, Wu CS, Tai MH (2020). Topical MTII Therapy Suppresses Melanoma Through PTEN Upregulation and Cyclooxygenase II Inhibition. International Journal of Molecular Sciences. PMID: 31968661

FAQ

Melanotan II is a synthetic cyclic heptapeptide analog of alpha-MSH, engineered with a lactam bridge for greater potency and stability than the natural hormone.[1]

Melanotan II is a non-selective agonist across multiple melanocortin receptor subtypes (MC1R, MC3R, MC4R, MC5R), engineered for greater potency and metabolic stability than the natural hormone it is derived from.

Published research spans pigmentation, feeding/energy-balance, sexual-function, and dermatological/oncology research models.[1][2][3][4]

Human research on Melanotan II's effects on sexual function informed the later development of bremelanotide, a more receptor-selective MC4R agonist studied separately in the literature.[3]

A COA for a Melanotan II research vial should report confirmed amino acid sequence and net peptide content, consistent with the documentation standard used across this catalog.

No. Melanotan II is supplied strictly under a Research Use Only framework for laboratory and preclinical investigation, and none of the studies referenced here involve clinical administration guidance.

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