The short version of alpha-MSH fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-10-10. Anything still debated is marked as such rather than presented as settled.
Melanotan-2 is a synthetic linear peptide built from seven amino acids arranged in a short chain. Its sequence is commonly written as Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-NH2, which includes a modified N-terminus and an amidated C-terminus. The molecule belongs to the melanocortin family and acts as a receptor agonist. Structural features such as the D-phenylalanine residue and the Nle substitution are associated with increased stability against enzymatic degradation relative to the natural parent peptide.
The compound emerged from research programs in the 1980s that examined analogues of alpha-melanocyte-stimulating hormone for pigmentation and photoprotection. Investigators modified the native sequence to extend activity duration and potency. A related analogue, afamelanotide, was developed within the same broad line of inquiry and eventually gained approval in certain jurisdictions for a rare light-sensitivity condition. Melanotan-2 itself did not progress through the same regulatory route and has no approved therapeutic indication.
Melanocortin receptors comprise five subtypes with distinct tissue distributions and functions. Melanotan-2 is described in the literature as a non-selective agonist that engages several of these subtypes, including MC1R, MC3R, MC4R, and MC5R. MC1R is the subtype most directly linked to melanin production in skin cells. Because the compound is not subtype-selective, its observed effects in experimental settings are generally attributed to activity across multiple receptor pathways rather than to a single target.
Melanocytes are the pigment-producing cells of the skin, and they carry melanocortin-1 receptors on their surface. When the receptor is activated, cyclic adenosine monophosphate rises inside the cell and raises the activity of enzymes such as tyrosinase, which increases melanin output. Melanotan-2 binds melanocortin-1 receptors in vitro and in animal models, and this binding is generally described as the basis for the tanning effect. Other receptors account for different effects: melanocortin-4 receptors contribute to appetite and erectile signalling, while melanocortin-3 and melanocortin-5 receptors contribute to energy balance and exocrine function.
Early published reports described melanotan-2 as a tanning agent without sun protection, which means darkening is not the same as protection against ultraviolet radiation. Later studies explored the peptide in erectile dysfunction, hemorrhagic shock, and some skin conditions. No regulator in the United States or Europe has approved it for clinical use. Many products labelled melanotan-2 are sold without approval and their identity and purity are unverified. Its long-term safety in humans remains an open question.
Melanotan-2, also written Melanotan II, is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, and the lactam bridge between the aspartate and lysine side chains constrains the peptide into a ring. This structural change increases receptor affinity and metabolic stability relative to the native hormone. The compound was created in the 1980s as a research tool for studying pigmentation biology.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms differ |
| Molecular weight | Approximately 1024 g/mol | Calculated for the free base |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water and polar solvents | Poorly soluble in non-polar solvents |
| Typical storage | -20 degrees Celsius, dry, protected from light | Refers to the solid form |
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According to Travis Hirschi's social control theory, adolescents with stronger attachments to family, religious, academic, and other social institutions are less likely to engage in delinquent and maladaptive behavior, such as drug use leading to addiction.
== Reactivity == Thiotepa is a reactive compound that, under acidic, neutral, or alkaline conditions, undergoes solvolysis, leading to potential side reactions such as polymerization and dimerization into piperazines. During acidic degradation, thiotepa reacts with chloride ions to produce monochloro, dichloro, and trichloro derivatives. Acidic conditions also result in the formation of tepa (N,N′,N″-triethylenephosphoramide), the first identified and more reactive metabolite of thiotepa. In alkaline media, thiotepa undergoes degradation, though no detectable byproducts were identified. Like other aziridine-containing compounds, hydroxyl substitution reactions may release aziridine. This degradation pathway has also been reported for tepa. The stability of thiotepa in biological samples is dependent on pH. In plasma, the monochloro derivative of thiotepa is formed, while in urine, both monochloro and dichloro derivatives have been found. Thiotepa is most stable between pH 7 and 11. In plasma under physiological conditions, the compound has a half-life of five days, whereas in urine at 37 °C, the half-life is 16 minutes at pH 4 and 21 hours at pH 6.
Tertiary structure may give way to the formation of quaternary structure in some proteins, which usually involves the "assembly" or "coassembly" of subunits that have already folded; in other words, multiple polypeptide chains could interact to form a fully functional quaternary protein.
Sources: en.wikipedia.org
These included the suppression of the uprising in East Germany (1953), Hungarian revolution (1956) and the invasion of Czechoslovakia (1968). The Soviet Union also began the war in Afghanistan between 1979 and 1989. In the Soviet Union, general conscription applied, meaning all able-bodied males aged 18 and older were drafted in the armed forces.
== External links == Human Health Campus, The official website of the International Atomic Energy Agency dedicated to Professionals in Radiation Medicine. This site is managed by the Division of Human Health, Department of Nuclear Sciences and Applications Canadian Organization of Medical Physicist - Organisation canadienne des physiciens médicaux The American Association of Physicists in Medicine medicalphysicsweb.org from the Institute of Physics AIP Medical Physics portal University of Toronto - Medical Biophysics Department Journal of Biophysics Institute of Physics & Engineering in Medicine (IPEM) - UK European Federation of Organizations for Medical Physics (EFOMP)
Microscopy is a category of characterization techniques which probe and map the surface and sub-surface structure of a material. These techniques can use photons, electrons, ions or physical cantilever probes to gather data about a sample's structure on a range of length scales. Some common examples of microscopy techniques include:
== History == Ferric maltol was approved for medical use in the European Union in February 2016. Ferric maltol was approved for medical use in the United States in July 2019, based on evidence from three clinical trials (NCT01340872, NCT01352221, and NCT02968368). All 295 participants had low iron stores in the body and consequent iron deficiency anemia. In the first two trials low iron was caused by participants' inflammatory bowel disease and in the last trial, by long standing (chronic) kidney disease. Trials were conducted at 79 sites in Europe and the United States. The efficacy of ferric maltol to treat iron deficiency in people aged 10-17 years of age was assessed in the FORTIS trial (NCT05126901). The trial treated 24 participants with age-based dosing of ferric maltol twice daily, and showed a clinically meaningful average increase in hemoglobin of 1.1 g/dL at week 12. This, on average, would be the expected increase in hemoglobin with one blood transfusion.
=== Age of onset === Feline hypersomatotropism is usually diagnosed in elderly cats. The average age of diagnosis is between 10 and 11 years with a range of 4–17 years. The age range of dogs reported with growth hormone secreting tumours is between 7 and 10 years. The age range of bitches with progestone induced hypersomatotropism is 4–11 years, for bitches with hypersomatotropism resulting from the estrous cycle the age range is between 6 and 13 years.
Sources: en.wikipedia.org
No. Melanotan-2 is manufactured synthetically. The naturally occurring peptide in the same family is alpha-melanocyte-stimulating hormone, which the body produces as part of normal endocrine and neural signalling.
Both are synthetic analogues derived from the same parent hormone. Reference descriptions usually characterise afamelanotide as more selective for the MC1R subtype, whereas melanotan-2 is reported to interact with a wider range of melanocortin receptors.
Early studies explored melanocortin signalling and pigmentation, which later led to informal use of the label tanning peptide. That label is not a regulatory category and does not imply approved status for any purpose.
No. It is a laboratory-made peptide, while the natural hormone is alpha-melanocyte-stimulating hormone, a longer peptide produced by the pituitary gland and by skin cells. Melanotan-2 mimics only a short active region of that hormone and contains non-natural residues such as D-phenylalanine.