Introduction to Melanotan II
Melanotan II (MT-II) is a synthetic cyclic peptide analog of alpha-melanocyte-stimulating hormone (?-MSH). Originally developed at the University of Arizona in the 1990s, it has become one of the most extensively studied peptides in melanocortin receptor research.
MT-II’s ability to activate multiple melanocortin receptor subtypes has made it a valuable research tool across dermatology, endocrinology, and neuroscience laboratories.
Molecular Profile
- Chemical name: Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2
- Classification: Non-selective melanocortin receptor agonist
- Amino acids: 7 (cyclic lactam structure)
- Molecular weight: 1,024.18 Da
- Structure type: Cyclic peptide (lactam bridge between Asp and Lys)
- Receptor targets: MC1R, MC3R, MC4R, MC5R
- Half-life: ~1-2 hours in research models
The Melanocortin Receptor System
The melanocortin system consists of five receptor subtypes (MC1R through MC5R), each with distinct tissue distribution and signaling functions:
- MC1R — Primarily in melanocytes; regulates melanin production and pigmentation
- MC2R — Adrenal cortex; ACTH receptor (MT-II does not significantly activate this)
- MC3R — Central nervous system, gut; energy homeostasis and feeding behavior
- MC4R — Hypothalamus; appetite regulation, sexual function, energy balance
- MC5R — Exocrine glands, immune cells; sebaceous gland function
Melanotan II activates MC1R, MC3R, MC4R, and MC5R with varying affinities, making it a broad-spectrum melanocortin research tool.
Mechanism of Action
Melanogenesis (MC1R Pathway)
MT-II binds MC1R on melanocytes, activating adenylyl cyclase and increasing cyclic AMP (cAMP) levels. This triggers a signaling cascade through protein kinase A (PKA) that upregulates tyrosinase — the rate-limiting enzyme in melanin synthesis. The result is increased eumelanin production.
Central Nervous System Effects (MC3R/MC4R)
Through hypothalamic MC3R and MC4R activation, MT-II modulates appetite-regulating circuits and sexual function pathways. MC4R in particular has been identified as a key node in the regulation of energy balance and reproductive behavior in research models.
Key Research Areas
Dermatology Research
- Melanogenesis mechanisms and pigmentation pathways
- UV-independent melanin production models
- Photoprotection research
- Vitiligo and hypopigmentation disorder modeling
Metabolic Research
- MC3R/MC4R role in appetite regulation
- Energy homeostasis pathway mapping
- Leptin-melanocortin signaling interactions
- Obesity-related receptor dysfunction studies
Neuroscience Research
- Melanocortin pathway involvement in sexual function
- Central nervous system receptor distribution
- Neuropeptide signaling cascade characterization
- Behavioral neuropharmacology models
Melanotan II vs Melanotan I
| Feature | Melanotan I (Afamelanotide) | Melanotan II |
|---|---|---|
| Structure | Linear (13 amino acids) | Cyclic (7 amino acids) |
| Selectivity | MC1R selective | Non-selective (MC1R, MC3R, MC4R, MC5R) |
| Primary Research Use | Pigmentation-focused | Broad melanocortin system |
| CNS Effects | Minimal | Significant (MC4R activation) |
| Half-Life | ~30 minutes | ~1-2 hours |
| Research Scope | Narrow (dermatology) | Broad (derm + neuro + metabolic) |
Storage and Handling
- Lyophilized powder: Store at -20°C, protect from light
- Reconstituted solution: 2-8°C, use within 4 weeks
- Reconstitution solvent: Bacteriostatic water
- Light sensitivity: MT-II is light-sensitive; always store in amber vials or wrapped in foil
- Stability note: Cyclic structure provides better stability than linear melanocortin analogs
For detailed protocols, see our Reconstitution Guide and Peptide Storage Guide.
Source Research-Grade Melanotan II
Proxiva Labs supplies Melanotan II at >99.99% verified purity with full third-party certificates of analysis. Manufactured in FDA-registered, GMP-certified U.S. facilities.
Browse our complete research peptide catalog or review our test results.
Disclaimer: All compounds are intended strictly for laboratory research and in-vitro use only. Not for human consumption.