Melanotan II
$49.95
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- Product is sold in powder form, needs reconstitution before use. Please read more on our FAQ page.
Melanotan II (MT-II) is a synthetic cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (α-MSH) from Pyrex Labs. It is a potent, non-selective agonist at four melanocortin receptors: MC1R, MC3R, MC4R, and MC5R. Unlike its linear counterpart afamelanotide (Melanotan I), Melanotan II is cyclic, offering enhanced stability and blood-brain barrier permeability.
Research applications include melanocortin receptor pharmacology, melanogenesis (pigmentation) studies, appetite and metabolic pathway research (MC4R-mediated), thermogenesis, and sexual behavior investigations. Each 5mg vial contains lyophilized powder tested to ≥98% purity by HPLC, with sequence confirmed by mass spectrometry.
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Melanotan II (MT-II) is a synthetic cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (α-MSH) from Pyrex Labs. Structurally, it is a potent, non-selective agonist at four of the five known melanocortin receptors: MC1R, MC3R, MC4R, and MC5R . This receptor promiscuity translates to a wide array of physiological effects in research models, including melanogenesis (pigmentation), modulation of sexual function, appetite suppression, and metabolic regulation .
Unlike its linear counterpart afamelanotide (Melanotan I), Melanotan II is a cyclic peptide with enhanced in vivo stability and blood-brain barrier permeability . It binds with high affinity to MC1R (Ki 0.67 nM) and MC4R (Ki 6.6 nM), activating Gs protein-coupled signaling cascades that increase intracellular cAMP and drive downstream effects such as MITF-mediated melanin synthesis .
Each 5mg vial contains lyophilized powder tested to ≥98% purity by HPLC, with sequence confirmed by mass spectrometry.
Best for: Melanocortin receptor research, MC1R signaling studies, appetite and metabolic pathway investigations, and comparative melanocortin agonist studies.
Key Research Applications
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Melanocortin Receptor Pharmacology: Investigates the non-selective agonist activity at MC1R, MC3R, MC4R, and MC5R, with negligible activity at MC2R
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Melanogenesis Research: Explores MC1R-mediated cAMP/PKA/CREB pathway activation and MITF upregulation leading to eumelanin synthesis
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Metabolic & Thermogenesis Studies: Examines MC4R-mediated effects on appetite suppression, energy expenditure, and adaptive thermogenesis in brown adipose tissue
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Sexual Behavior Research: Investigates melanocortinergic modulation of sexual function, with studies showing spontaneous erections as a pharmacological observation in rodent models
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Social Behavior & Oxytocin Studies: Explores MT-II-induced central oxytocin release and its effects on social learning and partner preference formation
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Oncology Research: Topical MT-II has been investigated for anti-melanoma properties through PTEN upregulation and COX-2/PGE2 pathway inhibition
Mechanism of Action
Melanotan II exerts its biological effects through activation of multiple melanocortin receptors, which are G protein-coupled receptors (GPCRs) :
Canonical Signaling (Gs Pathway):
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Activation of adenylyl cyclase → increased intracellular cAMP → PKA activation → CREB phosphorylation → target gene expression
Receptor Binding Affinities (Ki):
| Receptor Subtype | Ki (nM) |
|---|---|
| MC1R | 0.67 |
| MC3R | 34 |
| MC4R | 6.6 |
| MC5R | 46 |
Data sourced from Tocris Bioscience
Functional Potencies (EC50):
| Receptor | Species | EC50 (nM) |
|---|---|---|
| MC1R (human) | cAMP accumulation | 110 |
| MC1R (mouse) | cAMP accumulation | 0.02-0.03 |
| MC4R (mouse) | Functional assay | 0.057 ± 0.024 |
Alternative Pathways: Beyond Gs/cAMP/PKA signaling, MC3R and MC4R can couple to Gq/11, activating phospholipase C (PLC) and mobilizing intracellular calcium. ERK1/2 signaling cascade activation has also been observed independently of PKA .
Specifications
| Specification | Detail |
|---|---|
| Product | Melanotan II (MT-II) |
| Synonyms | MTII, Melanotan-II, Ac-Nle-c[Asp-His-DPhe-Arg-Trp-Lys]-NH₂ |
| Molecular Formula | C₅₀H₆₉N₁₅O₉ |
| Molecular Weight | 1024.2 Da |
| Structure | Cyclic heptapeptide |
| Form | Lyophilized white powder, sealed glass vial |
| Purity | ≥98% (HPLC) |
| Solubility | Water / Bacteriostatic water |
| Target Receptors | MC1R, MC3R, MC4R, MC5R (agonist) |
| Storage (lyo) | −20°C, desiccated, protected from light |
| Storage (reconstituted) | 2–8°C short term; aliquot at −20°C for long term |
| Intended use | Laboratory and in-vitro research only |
Research Notes
Structural Comparison: Melanotan II is a cyclic heptapeptide, while afamelanotide (Melanotan I) is a linear peptide. The cyclic structure of MT-II enhances in vivo stability and blood-brain barrier permeability, making it a more potent but also less selective research tool .
Key Distinction from Afamelanotide:
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Melanotan II: Non-selective (MC1R, MC3R, MC4R, MC5R); crosses blood-brain barrier; produces broader effects including sexual and metabolic modulation
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Afamelanotide: Selective for MC1R; does not cross blood-brain barrier; approved for EPP under medical supervision
Observed Pharmacological Effects in Research:
| Effect | Mediating Receptor | Research Context |
|---|---|---|
| Melanogenesis (pigmentation) | MC1R | Observed after 5 low doses in pilot Phase-I study |
| Appetite suppression | MC4R | Demonstrated in rodent models |
| Enhanced sexual function | MC4R | Spontaneous erections observed 1-5 hours post-administration |
| Thermogenesis modulation | MC4R | Partial rescue of impaired thermogenic capacity in PACAP-deficient mice |
| Oxytocin release | Melanocortin receptors | Enhances social learning in prairie vole models |
Quality Assurance
Every lot of Melanotan II undergoes comprehensive release testing against internal specifications, including:
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HPLC for purity confirmation (≥98%)
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Mass spectrometry for identity verification
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Visual inspection of vial integrity
Each vial is coded with a lot number that links directly to release testing documentation. A lot-specific Certificate of Analysis (COA) is available upon request.
Reconstitution Guidance
Reconstitute Melanotan II with sterile water or bacteriostatic water (0.9% benzyl alcohol) for research use. Direct diluent gently down the inner wall of the vial rather than onto the lyophilized cake. Swirl slowly until fully dissolved — do not shake.
Many investigators use 0.5-2 mL per vial to achieve working concentrations. For best results, aliquot the reconstituted solution into single-use tubes immediately to avoid repeated freeze-thaw cycles.
Storage & Stability
Before Reconstitution: Store the unopened, lyophilized vial at −20°C in a desiccated, light-protected environment. Stable under these conditions for the shelf-life indicated on the certificate of analysis.
After Reconstitution: Store working solutions at 2–8°C for short-term use (up to 7-14 days). For long-term storage, prepare single-use aliquots and freeze at −20°C. Avoid repeated freeze-thaw cycles.
Related Products from Pyrex Labs
Researchers who order Melanotan II frequently also purchase:
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Afamelanotide (Melanotan I) – For comparative MC1R selectivity studies
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PT-141 (Bremelanotide) – C-terminal fragment of MT-II for sexual behavior research
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KPV – Anti-inflammatory tripeptide derived from α-MSH
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MOTS-c – For mitochondrial and metabolic research
Frequently Asked Questions
What is the difference between Melanotan I and Melanotan II? Melanotan I (afamelanotide) is a linear peptide selective for MC1R that does not cross the blood-brain barrier. Melanotan II is a cyclic peptide that is non-selective (MC1R, MC3R, MC4R, MC5R) and crosses the blood-brain barrier, producing broader physiological effects including metabolic and sexual modulation .
What receptors does Melanotan II target? Melanotan II is an agonist at MC1R, MC3R, MC4R, and MC5R, with negligible activity at MC2R (ACTH receptor) .
What research has been conducted with Melanotan II? Melanotan II has been studied in contexts including melanocortin receptor pharmacology, melanogenesis, thermogenesis and energy expenditure (mouse models), sexual behavior, social learning and oxytocin release (prairie vole studies), and topical anti-melanoma research .
Is Melanotan II approved for human use? No. This product is for research purposes only and is not FDA-approved for human consumption, medical treatment, or veterinary applications. Regulatory agencies in the US, UK, and Australia have issued warnings against its use outside approved research settings .
Do you provide a Certificate of Analysis? Yes. A lot-specific COA is available upon request for every vial shipped.
