A practical reference on Alpha-MSH: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2025-11-02. 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.
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
Regulatory treatment varies between countries. Several national medicines agencies have classified the peptide as unapproved, and customs authorities in some jurisdictions seize shipments on that basis. A few jurisdictions channel supply through prescription-only frameworks that do not list the substance by name. Because the material circulates mainly through online vendors, composition and purity are rarely verified before sale. Surveys of unapproved peptide products have reported labels that did not match measured content in a substantial fraction of samples.
Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its structure substitutes a lactam bridge between side chains to increase stability relative to the native hormone. The compound is also known by the shorthand MT-II and by several non-proprietary synonyms used in research catalogues. It is not an approved therapeutic product in any major jurisdiction; material sold under this name is typically offered as a laboratory reagent rather than as a medicine.
| 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 |
Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.
Melanotan II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
Receptor-binding studies classify melanotan II as a non-selective melanocortin agonist. It interacts with MC1R, MC3R, MC4R and MC5R, with reported affinities in the low nanomolar range and no strong subtype preference. Activation of MC1R on dermal melanocytes shifts pigment synthesis toward eumelanin, the dark polymer deposited in melanosomes and transferred to keratinocytes. Because the same peptide engages MC4R in the hypothalamus, it also appears in animal work on food intake and erectile response, which is why it is discussed in both pigment and metabolic research. Which receptor populations dominate after systemic exposure in humans is not fully established.
Two structural changes distinguish the synthetic peptide from the natural hormone. A norleucine residue replaces methionine at one position, and a D-configured phenylalanine replaces the natural L-form at another. Both substitutions slow enzymatic breakdown, which extends the molecule's persistence relative to the parent hormone. The lactam bridge further constrains the backbone into a stable conformation. These features are standard design strategies in peptide chemistry and are not unique to this compound; they appear across many research peptides built for improved stability.
The compound was developed in the late 1980s and early 1990s by academic researchers investigating melanocortin signaling and pigmentation. Early work explored whether synthetic analogs could reproduce effects of the natural hormone under controlled conditions. The molecule never advanced through the full regulatory pathway required for approval as a medicine. From the mid-2000s onward it appeared in unregulated consumer markets, often distributed through informal channels. That gap between research origins and commercial availability shapes how the compound is discussed today.
=== Children === A review of loperamide in children under twelve years of age found that serious adverse events occurred only in children under three years of age. The study reported that the use of loperamide should be contraindicated in children who are under three years of age, systemically ill, malnourished, moderately dehydrated, or have bloody diarrhea. In 1990, all formulations of loperamide for children were banned in Pakistan. Formulations for children aged less than twelve years of age are only available via prescription in the UK.
The Portuguese colonial administration in Brazil had two objectives that would ensure colonial order and the monopoly of Portugal's wealthiest and largest colony: to keep under control and eradicate all forms of slave rebellion and resistance, such as the Quilombo of Palmares, and to repress all movements for autonomy or independence, such as the Inconfidência Mineira (1789).
=== 2019 car accident handling === In June 2019, Morgan was involved in a minor collision in his newly purchased Bugatti Veyron, and he was captured on video slamming on the other driver's window and yelling, "Bitch, get out of the car". According to Mercury News, the other driver was traumatized by Morgan's conduct. A CBS News reporter visited Morgan to get his side of the story and Morgan allowed the reporter through his gate, answered the door himself, but refused to talk.
=== Migraine prevention === In its 2012 guidelines, the American Academy of Neurology stated that high-dose riboflavin (400 mg) is "probably effective and should be considered for migraine prevention," a recommendation also provided by the UK National Migraine Centre. A 2017 review reported that daily riboflavin taken at 400 mg per day for at least three months may reduce the frequency of migraine headaches in adults. Research on high-dose riboflavin for migraine prevention or treatment in children and adolescents is inconclusive, and so supplements are not recommended.
Sources: en.wikipedia.org
==== Indigenous ==== Black bears feature prominently in the stories of some of North America's indigenous peoples. One tale tells of how the black bear was a creation of the Great Spirit, while the grizzly bear was created by the Evil Spirit. In the mythology of the Haida, Tlingit and Tsimshian people of the northwest coast, mankind first learned to respect bears when a girl married the son of a black bear chieftain. In Kwakwa̱ka̱ʼwakw mythology, black and brown bears became enemies when Grizzly Bear Woman killed Black Bear Woman for being lazy. Black Bear Woman's children, in turn, killed Grizzly Bear Woman's children. The Navajo believed that the Big Black Bear was chief among the bears of the four directions surrounding Sun's house and would pray to it in order to be granted its protection during raids. Sleeping Bear Dunes in Michigan is named after a Native American legend, where a female bear and her two cubs swam across Lake Michigan to escape a fire on the Wisconsin shore. The mother bear reached the shore and waited for her cubs, but they did not make it across. Two islands mark where the cubs drowned, while the dune marks the spot where the mother bear waited.
Research into the clinical use of a recombinant form of human Activated Protein C (rhAPC) known as Drotrecogin alfa-activated, branded Xigris by Eli Lilly and Company, has been surrounded by controversy. Eli Lilly ran an aggressive marketing campaign to promote its use for people with severe sepsis and septic shock and sponsored the 2004 Surviving Sepsis Campaign Guidelines. However, a 2012 Cochrane review found that its use cannot be recommended since it does not improve survival and increases bleeding risk. In October 2011, Xigris was withdrawn from the market by Eli Lilly due to a higher mortality in a trial among adults.
== Nomenclature == Despite formal recommendation to the contrary, the term partition coefficient remains the predominantly used term in the scientific literature. In contrast, the IUPAC recommends that the title term no longer be used, rather, that it be replaced with more specific terms. For example, partition constant, defined as
== Applications == Stability constant values are exploited in a wide variety of applications. Chelation therapy is used in the treatment of various metal-related illnesses, such as iron overload in β-thalassemia sufferers who have been given blood transfusions. The ideal ligand binds to the target metal ion and not to others, but this degree of selectivity is very hard to achieve. The synthetic drug deferiprone achieves selectivity by having two oxygen donor atoms so that it binds to Fe3+ in preference to any of the other divalent ions that are present in the human body, such as Mg2+, Ca2+ and Zn2+. Treatment of poisoning by ions such as Pb2+ and Cd2+ is much more difficult since these are both divalent ions and selectivity is harder to accomplish. Excess copper in Wilson's disease can be removed by penicillamine or Triethylene tetramine (TETA). DTPA has been approved by the U.S. Food and Drug Administration for treatment of plutonium poisoning. DTPA is also used as a complexing agent for gadolinium in MRI contrast enhancement. The requirement in this case is that the complex be very strong, as Gd3+ is very toxic. The large stability constant of the octadentate ligand ensures that the concentration of free Gd3+ is almost negligible, certainly well below toxicity threshold. In addition the ligand occupies only 8 of the 9 coordination sites on the gadolinium ion. The ninth site is occupied by a water molecule which exchanges rapidly with the fluid surrounding it and it is this mechanism that makes the paramagnetic complex into a contrast reagent.
== Theoretical studies == There have been several theoretical studies on equilibrium thermodynamics of methane clumped isotopologues since 2008. These studies are based on ab initio, from underlying physical chemistry principles, and do not rely on empirical, or lab-based, data. Ma et al. utilized first-principle quantum mechanism molecular calculation (Density Functional Theory, or DFT) to study the temperature dependence of the 13CH3D abundance. Cao and Liu estimated
Sources: en.wikipedia.org
=== Pharmacodynamics === AM-1235 is a cannabinoid receptor agonist with Ki of 1.5 nM at CB1 compared to 20.4 nM at CB2. While the 6-nitro substitution on the indole ring reduces affinity for both CB1 and CB2 relative to the unsubstituted parent compound AM-2201, CB2 affinity is reduced much more, resulting in a CB1 selectivity of around 13 times. This is in contrast to other related compounds such as AM-1221 where a 6-nitro substitution instead confers significant selectivity for CB2.
In ancient warfare, militaries generally lived off the land, relying on whatever food they could forage, steal, purchase, or requisition. Armies that brought food supplies along with them would have to resort to carrying them in baggage trains and having soldiers carry their rations themselves. In Mesopotamia, most workers, including soldiers, were given rations of barley, oil, and wool. The first standing army in recorded history formed in ancient Mesopotamia under the reign of Sargon of Akkad, and as the army grew with his conquests, a military bureaucracy formed. According to letters from the time of Sargon II, the primary ration for his army was grain. The letters describe what types of grain are to be held for a campaign, in which locations, which grain to give to the soldiers and which to store as fodder for the pack animals, and provide lists of how much grain to give to the soldiers of specific ranks. In ancient Egypt, soldiers brought whatever they could carry in battle, but were provided with good food and wine while in their camps. Archaeologists have discovered small wooden tokens dating from the Middle Kingdom period carried by soldiers which were to be handed over in exchange for rations in Lower Nubia. The tokens carry inscriptions declaring the amount of bread a soldier is to be issued every ten days. Writing in Histories, Herodotus described warriors serving as the Pharaoh's bodyguards receiving a daily provision of five minae of roast grain, two minae of beef, and four cups of wine. One mina is equivalent to approximately 1.25 pounds (570 g).
=== Droplet incubation === In order to make droplet-based microfluidics a viable technique for carrying out chemical reactions or working with living cells on the microscale, it is necessary to implement methods allowing for droplet incubation. Chemical reactions often need time to occur, and living cells similarly require time to grow, multiply, and carry out metabolic processes. Droplet incubation can be accomplished either within the device itself (on-chip) or externally (off-chip), depending on the parameters of the system. Off-chip incubation is useful for incubation times of a day or more or for incubation of millions of droplets at a time. On-chip incubation allows for integration of droplet manipulation and detection steps in a single device.
== History == The glyoxylate cycle was discovered in 1957 at the University of Oxford by Sir Hans Kornberg and his mentor Hans Krebs, resulting in a Nature paper Synthesis of Cell Constituents from C2-Units by a Modified Tricarboxylic Acid Cycle. Kornberg and Krebs utilized isotopic labeling with C-14 acetate to demonstrate that in the glyoxylate pathway, the acetate is incorporated into the succinate intermediate while bypassing the decarboxylation steps of the TCA cycle. Their results from isotopic experiments laid the foundation for the alternative glyoxylate cycle and explained how plants as well as microorganisms convert two-carbon molecules into carbohydrates. Following this discovery, in 1967 Breidenbach and Beevers discovered that there is a specialized organelle in castor bean (Ricinus communis), glyoxysomes, which are specialized peroxisomes where the glyoxylate cycle enzymes are found and where the cycle takes place in plants.
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. No major regulatory agency has granted a marketing authorisation for melanotan II as a medicine. Products sold under this name are generally presented as laboratory reagents and are not subject to the batch-release testing applied to approved drugs.