A practical reference on Melanotan II: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-05-12. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Compound class | Synthetic cyclic heptapeptide | Alpha-MSH analogue containing a D-phenylalanine residue |
| Molecular formula | C50H69N15O9 | Average molecular mass approximately 1024.2 g/mol |
| Appearance | White to off-white lyophilised powder | Normally supplied as a freeze-dried solid in a sealed vial |
| Solubility | Freely soluble in water and polar solvents | Dissolves readily in aqueous buffers and in alcohol-water mixtures |
| Receptor targets | MC1R, MC3R, MC4R, MC5R | Acts as a non-selective melanocortin receptor agonist |
Outside regulated medicine, melanotan II circulates through online vendors as a research chemical, often marketed for tanning. Products sold this way vary widely in purity, concentration, and labeling accuracy, and independent testing has documented discrepancies. Published reports describe both pigment effects and adverse reactions, including nausea, flushing, and darkening of existing moles. Long-term safety data are sparse, and no large controlled trial has established a risk profile. Questions about cumulative effects on melanocytes remain unresolved in the literature.
Melanotan II is a synthetic peptide analog modeled on alpha-melanocyte-stimulating hormone, a naturally occurring signaling peptide involved in pigmentation. Its structure is a cyclic heptapeptide containing two non-natural substitutions, norleucine at position four and D-phenylalanine at position seven. These modifications resist enzymatic breakdown and extend the molecule's activity relative to the native hormone. The compound binds melanocortin receptors and is studied mainly as a pharmacological tool rather than a therapeutic product. It has never received approval as a medicine in any major jurisdiction.
The compound was developed in the late 1980s and 1990s by academic researchers investigating photoprotection. The rationale held that stimulating melanin production might reduce ultraviolet damage to skin and lower skin cancer risk. Early work examined receptor binding, pigment response, and short-term tolerability in small studies. That program did not produce an approved drug, and formal development stalled after early-phase trials. Whether induced pigmentation confers meaningful photoprotection remains an open question.
This reaction is exploited in native chemical ligation, a protocol for peptide synthesis. In a related reaction, thioesters can be converted into esters. Thioacetate esters can also be cleaved with methanethiol in the presence of stoichiometric base, as illustrated in the preparation of pent-4-yne-1-thiol:
In a survey of the general population, it was found that although many erect penises point upwards, it is common and normal for the erect penis to point nearly vertically upwards or horizontally straight forward or even nearly vertically downwards, all depending on the tension of the suspensory ligament that holds it in position. 37% of healthy men have a penile curve. With 22.2% of men having upwards curvature and 14.8% of men having downwards curvature.
It occurs more often in the developing world in association with malnutrition. Rates among refugees are reported at 5 to 45 percent. Scurvy was described as early as the time of ancient Egypt, and historically it was a limiting factor in long-distance sea travel, often killing large numbers of people. During the later Age of Sail, it was assumed that 50 percent of the sailors would die of scurvy on a major voyage of exploration. In long sea voyages, crews were isolated from land for extended periods and these voyages relied on large staples of a limited variety of foods; the lack of fruit, vegetables, and other foods containing vitamin C in diets of sailors resulted in scurvy.
233U(22Ne,xn)255−xNo The synthesis of neutron deficient nobelium isotopes was studied in 1975 at the FLNR. In their experiments they observed a 250 s SF activity, which they tentatively assigned to 250No in the 5n exit channel. Later results have not been able to confirm this activity and it is currently unidentified.
Sources: en.wikipedia.org
where Qn is the matrix Q multiplied by itself enough times to give its nth power. If Q is diagonalizable, the matrix exponential can be computed directly: let Q = U−1 Λ U be a diagonalization of Q, with
At the beginning of the war, the U.S. was neutral in the conflict because of its opposition to European colonialism, because the Việt Minh had recently been U.S. allies, and because, in the context of the Cold War, most of its attention was focused on Europe where Winston Churchill argued an "Iron Curtain" had fallen. The 1949 victory of Mao Zedong's Chinese Communist Party in the Chinese Civil War, the recognition of the DRV by the USSR and the newly formed People's Republic of China in January 1950, which prompted the US and the UK to recognize the State of Vietnam in response, and the signing of the Sino-Soviet Treaty of Friendship shortly after in February, shifted the US stance on the matter, and the war came to be viewed as another front in the anticommunist struggle. Indochina, and Southeast Asia more broadly, was declared vital by the U.S. government, and the containment of communism at the southern Chinese border, and, later, Korea, became one of the priorities of American foreign policy as it was believed that the fall of Indochina to communist hands would lead to the loss of other nations in the region. At this time, communism was seen as a uniform bloc, dominated by the Soviet Union. It was feared in Washington that if Ho were to win the war, he would establish a state politically aligned with Moscow, with the Soviets ultimately controlling Vietnamese affairs. This prospect spurred the U.S. to support France in their war effort, primarily through the Mutual Defense Assistance Act. In May 1950, after Chinese communist forces occupied Hainan island, U.S.
== Function == This gene encodes a protein that belongs to the microtubule-associated protein family. The proteins of this family are thought to be involved in microtubule assembly, which is an essential step in neurogenesis. The product of this gene is a precursor polypeptide that presumably undergoes proteolytic processing to generate the final MAP1B heavy chain and LC1 light chain. Gene knockout studies of the mouse microtubule-associated protein 1B gene suggested an important role in development and function of the nervous system. Two alternatively spliced transcript variants have been described.
At low enough temperatures, a distinction can be made between the axial and equatorial hydrogens in cyclohexane. An example of nuclear magnetic resonance being used in the determination of a structure is that of buckminsterfullerene (often called "buckyballs", composition C60). This now famous form of carbon has 60 carbon atoms forming a sphere. The carbon atoms are all in identical environments and so should see the same internal H field. Unfortunately, buckminsterfullerene contains no hydrogen and so 13C nuclear magnetic resonance has to be used. 13C spectra require longer acquisition times since carbon-13 is not the common isotope of carbon (unlike hydrogen, where 1H is the common isotope). However, in 1990 the spectrum was obtained by R. Taylor and co-workers at the University of Sussex and was found to contain a single peak, confirming the unusual structure of buckminsterfullerene.
α-Ketoisovaleric acid is an organic compound with the formula (CH3)2CHC(O)CO2H. It is a ketoacid. With a melting point just above room temperature, it is usually an oil or semi-solid. The compound is colorless. It is a metabolite of valine and a precursor to pantothenic acid, a prosthetic group found in several cofactors. In the biological context, is usually encountered as its conjugate base ketoisovalerate, (CH3)2CHC(O)CO2−.
Sources: en.wikipedia.org
== History == Established in 1984, the International Petroleum Investment Company (IPIC) was created to advance Abu Dhabi's natural petroleum wealth for the development of the emirate. Mubadala Development Company followed in 2002 to further diversify the economy. In June 2016, it was announced that Mubadala Development Company would merge with the International Petroleum Investment Company. In 2017, ownership of both MDC and IPIC was transferred to a newly created parent company, Mubadala Investment Company. The company is a wholly owned investment vehicle of the government of Abu Dhabi, and Sheikh Mansour bin Zayed Al Nahyan, vice-president and deputy prime minister of the United Arab Emirates, is chairman of the company.
== External links == WHO Snake Antivenoms Database Organization (2016). Guidelines for the management of snakebites. Regional Office for South-East Asia, World Health Organization. hdl:10665/249547. ISBN 978-92-9022-530-0.
One common division of Raleigh is to differentiate the central part of the city, which lies inside of the circumferential highway known as the Raleigh Beltline (I-440 and I-40) from areas outside of the Beltline. The area inside of the beltline includes the entirety of the central business district known as Downtown Raleigh, as well as several more residential areas surrounding it. The downtown area is home to historic buildings such as the Sir Walter Raleigh Hotel built in the early 20th century, the restored City Market, the Fayetteville Street downtown business district (which includes the PNC Plaza and Wells Fargo Capitol Center buildings), as well as the North Carolina Museum of History, North Carolina Museum of Natural Sciences, North Carolina State Capitol, William Peace University, the City of Raleigh Museum, Raleigh Convention Center, Shaw University, Campbell University School of Law, and St. Augustine's College. In the 2000s, an effort by the Downtown Raleigh Alliance was made to separate this area of the city into five smaller districts: Fayetteville Street, Moore Square, Glenwood South, Warehouse, and Capital District. The nearby Blount Street Historic District includes many of the city's historic Victorian, Georgian Revival, Queen Anne, and Second Empire mansions, including Norris-Heartt House, Andrews-Duncan House, Heck-Andrews House, Bailey-Tucker House, Capehart House, Bailey-Bunn House, and the Garland Scott and Toler Moore Tucker House (the latter was later moved from its original location to Oakwood).
==== MeSH D06.472.759 – placental hormones ==== MeSH D06.472.759.367 – chorionic gonadotropin MeSH D06.472.759.367.125 – chorionic gonadotropin, beta subunit, human MeSH D06.472.759.367.562 – glycoprotein hormones, alpha subunit MeSH D06.472.759.451 – gonadotropins, equine MeSH D06.472.759.692 – placental lactogen
Sources: en.wikipedia.org
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.
No approved regulatory indication exists in major markets. An approval exists for a different peptide, afamelanotide, which is used for a rare photosensitivity disorder called erythropoietic protoporphyria. Melanotan-2 itself remains a research compound with no cleared clinical role.
Melanocortin-1 receptors on melanocytes are the receptor most closely linked to pigment production. The peptide is not selective, however, and also activates melanocortin-3, melanocortin-4, and melanocortin-5 receptors. That lack of selectivity is the usual explanation offered for both its range of observed effects and its off-target effects.
No. It is a synthetic analogue carrying four amino acid changes, a lactam ring and an amidated C-terminus. The natural hormone is a linear thirteen-amino-acid peptide processed from proopiomelanocortin.