≥98%HPLC Purity
COAIncluded
USAShipped
Melanotan II (MT-2) Peptide
Cyclic heptapeptide analog of alpha-MSH targeting melanocortin receptors MC1R through MC5R. Originally developed at University of Arizona for melanogenesis research. Non-selective melanocortin agonist studied for tanning response, sexual function, appetite modulation, and immune regulation.
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| SKU | ACR-MT2 |
|---|---|
| CAS Number | 121062-08-6 |
| Molecular Formula | C50H69N15O9 |
| Molecular Weight | 1024.18 g/mol |
| Sequence | Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 |
| Purity | ≥98% |
| Physical Form | Lyophilized Powder |
| Storage | Store at -20°C |
What is Melanotan II (MT-2)?
Melanotan II (MT-2, MT2) is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂, molecular weight 1,024.18 g/mol, and CAS number 121062-08-6. Developed at the University of Arizona by Dr. Victor Hruby in the late 1980s, MT-2 is a non-selective agonist of melanocortin receptors MC1R through MC5R (except MC2R).
MT-2 was originally designed to induce melanogenesis (tanning) as a potential protective strategy against UV-induced skin cancer. However, its broad melanocortin receptor activity produces multiple effects: skin darkening (MC1R), sexual arousal (MC3R/MC4R), appetite suppression (MC4R), and immune modulation (MC1R/MC3R). This multifunctional profile has made MT-2 one of the most widely studied melanocortin peptides in preclinical research.
MT-2 is the parent compound from which PT-141 (Bremelanotide) was derived by converting the C-terminal amide to a free acid — eliminating melanogenesis while preserving sexual function effects.
Mechanism of Action
Melanotan II is a non-selective melanocortin receptor agonist with activity at multiple receptor subtypes:
MC1R (Melanogenesis): The primary tanning receptor on melanocytes. MT-2 binding activates cAMP/PKA → MITF → tyrosinase cascade, increasing eumelanin production. This produces darkening of skin, hair, and nevi without UV exposure. MC1R activation also provides photoprotective and anti-inflammatory effects in skin.
MC3R (Energy Homeostasis): Expressed in hypothalamus and peripheral tissues. MC3R regulates energy partitioning between lean and fat tissue, feeding behavior, and cardiovascular function. MT-2 activates MC3R, contributing to its anti-obesity and cardiovascular effects in animal models.
MC4R (Appetite/Sexual Function): The critical receptor for both appetite suppression (hypothalamic POMC/CART neuron activation) and sexual arousal (PVN oxytocin/dopamine release). MT-2 is a potent MC4R agonist — this is the receptor responsible for the sexual function effects that led to development of PT-141.
MC5R (Exocrine Glands): Regulates sebaceous gland secretion and pheromone production. Less studied but contributes to MT-2 peripheral effects.
The cyclic structure of MT-2 confers resistance to enzymatic degradation compared to linear alpha-MSH, resulting in a much longer duration of action (hours vs minutes).
Research & Clinical Studies
MT-2 and Melanogenesis/Tanning Research
The landmark Phase I trial by Dorr et al. (1996) established MT-2 melanogenic efficacy in humans:
- Subcutaneous MT-2 administration (0.01-0.025 mg/kg) produced significant skin darkening within 5 days
- Melanin increase was measurable by reflectance spectrophotometry across all skin phototypes
- Tanning occurred without UV exposure — confirming direct melanocyte activation
- The tanning response was dose-dependent and persisted for 2-3 weeks after discontinuation
- Darker-skinned subjects (Fitzpatrick III-IV) showed more pronounced responses than fair-skinned (I-II)
The UV-independent melanogenesis is pharmacologically significant because eumelanin provides natural photoprotection (UV absorption, free radical scavenging) without the DNA damage associated with UV tanning.
[1] 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. PubMed ↗
MT-2 and Sexual Function Research
MT-2 unexpectedly produced penile erections during Phase I melanogenesis trials — a finding that redirected significant research effort toward melanocortin-based sexual function therapeutics.
- 9 of 10 male subjects in early trials reported spontaneous erections post-injection
- The erectogenic effect was mediated through MC4R activation in the hypothalamic paraventricular nucleus (PVN)
- MC4R activation triggers oxytocin and dopamine release in descending pathways to spinal erection centers
- This central mechanism is fundamentally different from PDE5 inhibitors (sildenafil), which act peripherally
This discovery led directly to the development of PT-141 (Bremelanotide) — a modified MT-2 analog with the C-terminal amide converted to free acid, reducing MC1R melanogenesis while preserving MC3R/MC4R sexual function. PT-141 was FDA-approved as Vyleesi in 2019 for HSDD.
[1] Wessells H et al. Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II. Int J Impot Res. 2000;12 Suppl 4:S74-79. PubMed ↗
MT-2 and Appetite/Obesity Research
MC4R is the primary melanocortin receptor for appetite regulation. MT-2 MC4R agonism produces:
- Significant appetite suppression in animal models (30-50% food intake reduction)
- Preferential reduction of fat mass over lean mass in DIO mice
- Effects mediated through hypothalamic POMC/CART neuron activation and AgRP/NPY neuron inhibition
- MC4R loss-of-function mutations are the most common monogenic cause of human obesity (4-6% of severe obesity cases)
The anti-obesity effect of MC4R agonism has been clinically validated: setmelanotide (Imcivree), a selective MC4R agonist derived from the same melanocortin research lineage as MT-2, was FDA-approved in 2020 for genetic obesity due to POMC, PCSK1, or LEPR deficiency.
Chemical & Physical Properties
| Full Name | Melanotan II (MT-2, MT2) |
|---|---|
| Sequence | Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂ |
| Molecular Formula | C₅₀H₆₉N₁₅O₉ |
| Molecular Weight | 1,024.18 g/mol |
| CAS Number | 121062-08-6 |
| Structure | Cyclic heptapeptide (lactam bridge Asp-Lys) |
| Non-natural AAs | Nle (norleucine), D-Phe (D-phenylalanine) |
| Receptors | MC1R, MC3R, MC4R, MC5R (non-selective) |
| Developer | University of Arizona (Dr. Victor Hruby) |
| Purity | ≥98% HPLC |
Handling & Reconstitution Guidelines
Reconstitution: Add bacteriostatic water slowly along vial wall. MT-2 dissolves readily as a small cyclic peptide (1,024 Da).
Concentration: 10 mg vial + 2 mL BAC water = 5 mg/mL. 20 mg vial + 2 mL = 10 mg/mL.
Note: MT-2 contains tryptophan (position 9 in the cyclic ring) which is photosensitive. Protect reconstituted solution from direct light. The cyclic lactam bridge provides enhanced proteolytic stability compared to linear melanocortin peptides.
Storage & Stability
Lyophilized: -20°C for 24+ months. 2-8°C for 6+ months. Room temperature stable for 30+ days (transit).
Reconstituted: 2-8°C, use within 28 days. Protect from light (Trp photosensitivity).
Stability advantage: The cyclic structure provides significantly better stability than linear alpha-MSH or ACTH fragments. MT-2 is resistant to aminopeptidases and carboxypeptidases due to the N-acetyl cap and C-terminal amide.
Frequently Asked Questions
What is MT2 peptide?
MT2 (Melanotan II) is a cyclic heptapeptide melanocortin receptor agonist. It activates MC1R (tanning), MC3R/MC4R (sexual function, appetite), and MC5R (exocrine glands). Originally developed at University of Arizona for UV-independent melanogenesis research. MW 1,024.18, CAS 121062-08-6.
What is the difference between Melanotan 1 and Melanotan 2?
Melanotan I (afamelanotide) is a linear 13-amino acid peptide selective for MC1R — it causes tanning only, without significant sexual function or appetite effects. Melanotan II is a cyclic 7-amino acid peptide that activates MC1-5R non-selectively — it causes tanning PLUS sexual arousal, appetite suppression, and other effects. MT-1 is more targeted; MT-2 is broader.
How is MT-2 related to PT-141 (Bremelanotide)?
PT-141 was derived directly from MT-2 by converting the C-terminal amide (-NH₂) to a free acid (-OH). This single modification eliminated MC1R melanogenesis (no tanning) while preserving MC3R/MC4R sexual function activity. PT-141/Bremelanotide was FDA-approved in 2019 as Vyleesi for HSDD.
What is the molecular weight and CAS of MT-2?
Melanotan II has MW 1,024.18 g/mol, molecular formula C₅₀H₆₉N₁₅O₉, and CAS number 121062-08-6. It is a cyclic heptapeptide with a lactam bridge between Asp and Lys residues, with Nle and D-Phe non-natural amino acids.
Does MT-2 peptide require UV exposure to work?
No. MT-2 activates melanocytes directly via MC1R, producing eumelanin without UV radiation. However, research shows UV exposure synergistically enhances the melanogenic response — MT-2 primes the melanocytes, and UV triggers additional melanin production on top of the baseline increase.
What sizes of Melanotan II are available?
Melanotan II is available in 10mg and 20mg lyophilized vials at ≥98% HPLC-verified purity. Certificate of Analysis included with every order. The cyclic peptide structure provides excellent shelf stability.
Is MT-2 banned by WADA?
Melanotan II is not specifically listed on the WADA prohibited list, but melanocortin receptor agonists may fall under the S2 (Peptide Hormones) or S0 (Non-approved Substances) categories depending on jurisdiction and application. Always verify current WADA status for competitive research contexts.
For laboratory and research use only. Not intended for human or animal consumption. All product information is derived from published preclinical research and does not constitute medical advice or claims.