Melanotan II
Also known as · MT-II · α-MSH analog · Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2
- EvidenceClinical
- CategoryMelanocortin
- RoutesubQ
- Half-life~1 hour (protease-resistant cyclic peptide)
- Form
- Lyophilized powder
- Purity
- ≥98% (HPLC)
- Molecular formula
- C50H69N15O9
- Molecular weight
- 1024.2 g/mol
- CAS number
- 121062-08-6
- Sequence
- Cyclic hexapeptide (see overview)
- COA
- Available on request
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Reserve vial →For research use only. Not for human consumption. Buyers must be affiliated with a research institution.
01 / Research summary
What the literature reports
Melanotan II is a synthetic cyclic hexapeptide analog of α-melanocyte-stimulating hormone (α-MSH), stabilized by a lactam bridge and non-natural residues (Nle at position 1, D-Phe at position 7). It is a non-selective melanocortin receptor agonist.
Cellaire classifies Melanotan II as early-phase clinical evidence. A double-blind crossover trial by Wessells et al. (J Urol 1998) in ten men with erectile dysfunction reported clinically apparent erections in 8 of 10 subjects at 0.025 mg/kg, alongside transient nausea and yawning. The Skin Cancer Foundation issued a public warning in July 2026 against use for tanning, and Melanotan II has never been FDA-approved.
02 / Reconstitution
Reconstitution reference
Illustrative unit math for a 10 mg vial reconstituted with 2 mL bacteriostatic water. This is not a dose recommendation.
03 / Overview
Molecular overview
Melanotan II is the cyclic peptide Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2. The cyclization is a lactam bridge between the Asp side chain and the Lys ε-amine, closing the 4–10 core of α-MSH into a stable ring.
It binds and activates multiple melanocortin receptors — MC1R (skin pigmentation), MC3R and MC4R (central appetite and sexual function), and MC5R. This non-selectivity produces the mixed effects observed clinically.
Human research is limited to small early-phase trials. Melanotan II is not FDA-approved for any indication, and unregulated use has been associated with dysplastic and darkened nevi and case reports of melanoma.
The Skin Cancer Foundation issued a formal warning against Melanotan II use for cosmetic tanning in July 2026.
04 / References