Melanotan II research: α-MSH and melanocortin receptors

Melanotan II research It focuses on the synthetic cyclic peptide analog of alpha-melanocyte-stimulating hormone (α-MSH) and its interaction with the melanocortin receptor system. In the scientific literature, Melanotan II is also referred to as MT-II or MTII and is mainly used as an experimental ligand in the study of the MC1R, MC3R, MC4R, and MC5R receptors.

When interpreting published results, it is important to distinguish between: endogenous α-MSH, synthetic Melanotan II, other melanocortin analogs, and specific research-grade material. Results obtained in a receptor-based, cellular, animal or historical clinical trial cannot be automatically transferred to a single commercially available laboratory batch.

What is Melanotan II?

Melanotan II (MT-II) is a synthetic cyclic peptide derived from the biologically active region of α-MSH. It belongs to the melanocortin analogues used in experimental research of receptor pharmacology and the structural and functional properties of the melanocortin system.

The PubChem database lists the molecular formula for Melanotan II. C₅₀H₆₉N₁₅O₉, relative molecular mass approximately 1024.2 g/mol and CAS 121062-08-6.

Technical source:

PubChem – Melanotan II.

Cyclic structure of Melanotan II

One of the characteristic features of the MT-II is its cyclic lactam structure. The cyclic arrangement was designed as part of the development of analogs of the biologically active part of α-MSH.

Compared to a linear natural peptide, Melanotan II also contains amino acid modifications, including norleucine and D-phenylalanine.

Such structural changes are important in research on the relationship between:

• by peptide conformation,
• receptor affinity,
• selectivity among receptor subtypes,
• and the stability of the molecule in experimental systems.

Therefore, when performing analytical comparisons, it is important not to work solely with the name „Melanotan II“, but to verify the specific molecular identity of the sample under investigation as well.

Melanotan II and α-MSH

α-MSH It belongs to the endogenous melanocortin peptides derived from the precursor proopiomelanocortin (POMC).

Melanotan II was created as a synthetic analogue of the biologically active region α-MSH. However, this does not mean that it is an identical molecule or that all the properties of natural α-MSH can be automatically attributed to MT-II.

Melanocyte receptors MC1R–MC5R

The melanocortin receptor system consists of several G protein receptors labeled MC1R to MC5R.

In the case of Melanotan II, the experimental literature mainly deals with binding and activity on receptors. MC1R, MC3R, MC4R and MC5R. Therefore, MT-II is not considered a highly selective ligand of a single receptor subtype.

Receptor studies allow comparing how structural changes in melanocortin analogs alter their affinity and selectivity among different receptor subtypes.

Primary source:

Selectivity of cyclic MSH analogues for melanocortin receptor subtypes.

What did receptor experiments show?

Experiments with cells expressing individual human melanocortin receptors have shown that cyclic MSH analogs, including MT-II, exhibit high receptor affinity, with their profile not limited to a single receptor.

Such data are important especially when:

• characterization of receptor ligands,
• comparing agonists and antagonists,
• the development of more selective experimental analogs,
• and the study of the structural elements necessary for binding to melanocortin receptors.

Historical human experimental data

Melanotan II was also the subject of very early pilot experimental research in humans.

In 1996, a small phase I study was published, which included only three healthy male volunteers. The researchers monitored the biological response and tolerance of MT-II in a controlled protocol.

The study recorded changes in pigmentation, and at the same time, several adverse effects were observed, including nausea, fatigue, and other physiological reactions.

Primary source:

Dorr et al. – Evaluation of melanotan-II in a pilot phase-I clinical study.

This historical work is important for understanding the development of the molecule, but its size and nature do not allow it to be interpreted as evidence of general clinical safety or approved medical use.

LC-MS/MS and analytical detection of Melanotan II

MT-II was also used as an analytical model in the development of mass spectrometry methods.

A published work from 2007 describes a quantitative method based on liquid chromatography combined with tandem mass spectrometry (LC-MS/MS).

The authors used the method to determine MT-II in the plasma and brain tissues of mice after experimental exposure.

Primary source:

LC-MS/MS quantification of Melanotan-II in plasma and brain tissue.

Such analytical work helps characterize the detection and distribution of the molecule in a specific experimental model. However, they do not automatically say anything about the purity or quantity of another commercially available batch.

Level of scientific evidence

Regulatory context of Melanotan II

Melanotan II should not be confused with a legally approved drug or consumer product.

The U.S. FDA has referred to Melanotan II sold for human use in its historical regulatory and enforcement documents as an unapproved new drug. The FDA also addressed cases where the material was labeled as „research use only,“ but the marketing or sales method was directed towards human use.

Official sources:

FDA – Melanotan II regulatory enforcement record

FDA – enforcement involving products including Melanotan II

Research-grade Melanotan II and analytical documentation

The scientific publication describes the molecule used in a specific experimental protocol. It does not automatically confirm the quality of a single commercially available batch.

When evaluating research-grade Melanotan II, the following are particularly relevant:

• precise molecular identity,
• cyclic form of a peptide,
• corresponding molecular weight,
• chromatographic purity,
• quantitative determination of quantity,
• batch number or lot number,
• the analytical method used,
• the traceability of the COA to the specific analyzed sample,
• the storage conditions stated on the label and in the CoA of the specific batch.

More information about the evaluation of purity, batch and documentation can be found in the article 7 criteria for selecting a peptide supplier.

The documentation available for the analyzed batches can also be verified in the section COA and analytical documentation.

What does the available research not show?

With Melanotan II, it is necessary to consistently distinguish between experimental receptor pharmacology and consumer claims.

The available data by themselves do not show:

• clinical safety of commercial research-grade Melanotan II,
• the suitability of the material for personal or humanitarian use,
• that the results of receptor cell experiments represent a health benefit,
• that the results from animal models automatically apply to humans,
• that the pilot study with three participants provides evidence of general clinical safety,
• that the material from the scientific study is identical to any commercially available batch,
• that the HPLC purity data is evidence of safety or efficacy.

Therefore, for a research-grade informational website, it is not appropriate to use consumer-oriented terms such as „instant tan,“ „tanning peptide,“ „increases libido,“ „burning fat,“ or other claims that refer to the results on the human body.

How to critically read studies on Melanotan II?

It is advisable to verify at each publication:

• whether MT-II or another α-MSH analogue was used,
• which melanocortin receptor was studied,
• whether it was a cellular, animal or human model,
• size of the experimental dataset,
• whether receptor affinity, biological response or analytical distribution was monitored,
• whether it is a primary experimental study or an overview article,
• and whether the result can be reproduced in an independent model.

Such an approach helps to separate the molecular mechanism from claims that would go beyond the published data.

FAQ – Melanotan II research

What is Melanotan II?

Melanotan II is a synthetic cyclic heptapeptide analog of the biologically active region of α-MSH. It is primarily used in research to study melanocortin receptors and receptor signaling.

Is Melanotan II the same as α-MSH?

No. α-MSH is an endogenous melanocortin peptide, while Melanotan II is a synthetic cyclic analog with multiple structural modifications.

Which receptors are being studied with Melanotan II?

The receptor-related studies published mainly evaluated MC1R, MC3R, MC4R and MC5R. MT-II is not highly selective only for one of these receptor subtypes.

Are there human studies of Melanotan II?

Yes. In 1996, a small pilot phase I study was published with three healthy men. However, this small experiment cannot be interpreted as confirmation of general safety or approved clinical use.

What is LC-MS/MS used for in Melanotan II?

LC-MS/MS can be used to analytically identify and quantify MT-II in experimental samples. However, the analytical method itself does not demonstrate clinical safety or efficacy.

Is an HPLC purity data sufficient for the research-grade MT-II?

No. Chromatographic purity is only one parameter. Molecular identity, quantity, batch, material form and other analytical data must be evaluated separately.

How is Melanotan II stored?

Research-grade material should be stored according to the data stated on the label and in the CoA of the specific batch. For a specific product, the batch-specific technical conditions always take precedence.

You can find more professional content in the section Research on peptides.

Scientific and regulatory sources

1. PubChem.
   Melanotan II – CID 92432.
   PubChem
2. Schiöth HB, Muceniece R, Wikberg JES.
   Selectivity of cyclic [D-Nal7] and [D-Phe7] substituted MSH analogues for the melanocortin receptor subtypes.
   Peptides. 1997.
   PubMed
3. Dorr RT, Lines R, Levine N, et al.
   Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study.
   Life Sciences. 1996.
   PubMed
4. A liquid chromatographic/tandem mass spectroscopic method for quantification of the cyclic peptide melanotan-II.
   PubMed
5. U.S. Food and Drug Administration.
   Regulatory enforcement record concerning Melanotan II.
   FDA