This is a working overview of alpha-MSH analogue, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-08-29. 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.
Quality assessment of research-grade peptide rests mainly on reversed-phase high-performance liquid chromatography for purity and on mass spectrometry for identity confirmation. A single main peak above a stated threshold, commonly ninety-eight percent by peak area, is the usual release criterion applied by suppliers. Independent analyses commissioned by laboratories and consumer organisations have repeatedly reported discrepancies between label claims and measured content, including truncated sequences, residual trifluoroacetate, and lower-than-declared peptide mass. Those findings do not establish that every supplier is unreliable, but they indicate that purity figures printed on a vial are claims requiring verification rather than settled facts.
Regulatory treatment varies by jurisdiction and has changed over time. In several countries the peptide is handled as an unapproved prescription medicine, and import or sale for human use is restricted, while elsewhere it falls under poisons or controlled-substance schedules. Enforcement activity against online vendors has been reported in Australia, New Zealand, the United Kingdom and the United States. Scholarly writing discusses melanotan-2 chiefly as an experimental tool and as a case study in unregulated peptide supply, and its precise legal position in any given country should be checked against current national schedules.
| 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 |
Structurally, Melanotan-2 retains the core recognition motif of alpha-melanocyte-stimulating hormone while adding a lactam bridge that links two side chains and constrains the molecule into a ring. This modification lowers susceptibility to enzymatic degradation. The compound acts as an agonist at melanocortin receptors, particularly subtypes associated with melanin production. Because the same receptor family influences several physiological processes, researchers note that its activity is not confined to pigmentation alone. Receptor selectivity continues to be examined in published studies.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its sequence incorporates modified residues that increase potency and extend biological activity relative to the native hormone. The compound binds receptors of the melanocortin family and is examined mainly in laboratory research. It does not occur naturally and exists only as a manufactured chemical entity produced by solid-phase synthesis.
The peptide was developed during the 1980s by researchers investigating melanocortin signalling and skin pigmentation pathways. Early work focused on analogues of alpha-melanocyte-stimulating hormone that would resist enzymatic breakdown more effectively than the parent molecule. Melanotan-2 emerged from that programme as a shortened, cyclised variant. Reports describing its synthesis and receptor activity later appeared in the scientific literature. Commercial availability grew through unregulated channels rather than through pharmaceutical approval.
Lyophilised peptide powder is comparatively stable when kept dry, cold and protected from light. Once dissolved, the molecule is exposed to hydrolysis, oxidation and microbial growth, and degradation accelerates at higher temperatures and in alkaline solution. Repeated freeze-thaw cycles concentrate solutes and promote aggregation. Handling guidance for research peptides commonly clusters around freezer temperatures for powder and short refrigerated use for reconstituted solutions, with pH control and sterile technique applied throughout.
Verification of a purchased sample requires documentation linking a batch to a certificate of analysis, and that document should be read for the methods used rather than the headline purity figure. A single chromatographic percentage does not establish identity. Independent laboratories can perform identity and content assays, but no such test establishes that a product is suitable for human use. Claims about efficacy rest largely on small, early studies rather than on replicated controlled trials, and that gap remains open.
Melanotan-2 is a synthetic cyclic heptapeptide designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous tridecapeptide that regulates pigment production. Two modifications distinguish it from the natural hormone: norleucine replaces methionine at the N-terminus, which limits oxidation, and a D-phenylalanine substitution raises receptor affinity. The ring is closed through an aspartate-lysine lactam bridge, giving the molecule a constrained conformation. The free base has a molecular mass near 1024 daltons, and commercial material is usually supplied as an acetate salt. It appears in the literature as a research peptide rather than an approved therapeutic agent.
Receptor studies place melanotan-2 among non-selective melanocortin agonists, binding MC1R, MC3R, MC4R and MC5R rather than a single subtype. Activation of MC1R on cutaneous melanocytes raises tyrosinase activity and shifts pigment synthesis toward eumelanin, which is darker and more photostable than pheomelanin. Central receptors, particularly MC4R, are associated with appetite suppression and with reported effects on sexual function. Because subtype selectivity is low, the same molecule engages pigment, metabolic and vascular pathways at once, and this breadth is a common explanation offered for the range of adverse events described in user reports.
=== Fluorine === 18F decays predominantly by β emission, with a half-life of 109.8 min. It is made by proton bombardment of 18O in a cyclotron or linear particle accelerator. It is an important isotope in the radiopharmaceutical industry. For example, it is used to make labeled fluorodeoxyglucose (FDG) or D-3-[18F]fluoroalanine for application in PET scans.
=== Receptor === The activation of cAMP/PKA by Ucn2 gives similar effects to the β-adrenergic pathway. Ucn2 increases left ventricular function independent of the β-adrenergic receptor but dependent on the binding of Ucn2 to CFR2. Ucn2 is an agonist for the G-protein coupled CRF1 and CRF2 receptors. It is highly selective for CRF2 which is predominantly found in the myocardium, blood vessels and peripheral tissues. This association provides reason for its strong cardiovascular effects. When Ucn2 binds CRF2 it activates adenyl-cyclase to increase cAMP which activates PKA and results in the noted changes to cardiovascular function. The ability of Ucn2 to produce PKA and alter calcium flux has led to the hypothesis that administration of Ucn2 may increase the risk of arrhythmias.
=== H. G. Wells === Author H. G. Wells was born in Bromley on 21 September 1866, to Sarah and Joseph Wells; his father was the founder of the Bromley Cricket Club and the proprietor of a shop that sold cricket equipment. Wells spent the first 13 years of his life in Bromley. From 1874 to 1879 he attended Tomas Morley's Bromley Academy, at 74 High Street. There was a 'H. G. Wells Centre' in Masons Hill near the southern end of the High Street which housed the Bromley Labour Club (the building was demolished in 2017). In August 2005, the wall honouring Wells in Market Square was repainted; the current wall painting features a rich green background with the same Wells reference and the evolutionary sequence of Homo sapiens featured in Origin of Species by Charles Darwin, a former resident of nearby Downe Village. Wells wrote about Bromley in an early unsigned article in the Pall Mall Gazette in which he expressed satisfaction that he had been born in an earlier, more rural Bromley. A blue plaque marks Wells' birthplace in Market Square, on the wall of what is now a Primark store. A marble plaque appears above the door of 8 South Street, the location of Mrs Knott's Dame school where "Bertie", as he was called as a child, learned to read and write. H. G. Wells featured Bromley in two of his novels: The War in the Air (which refers to Bromley as Bunhill) and The New Machiavelli (in which Bromley is referred to as Bromstead). However, H. G.
Pyrite's metallic luster and pale brass-yellow hue give it a superficial resemblance to gold, hence the well-known nickname of fool's gold. The color has also led to the nicknames brass, brazzle, and brazil, primarily used to refer to pyrite found in coal.
Sources: en.wikipedia.org
== Other projects == Staley shared lead vocals with Ann Wilson for a cover of Bob Dylan's "Ring Them Bells", featured on Heart's 1993 album Desire Walks On. The song "It's Coming After" from Second Coming's 1994 debut album L.O.V.Evil features Staley on lead vocals. Second Coming features Staley's bandmates from Alice N' Chains, his former band. One of the last songs that Staley recorded was a cover of Pink Floyd's "Another Brick in the Wall" with the supergroup Class of '99, featuring guitarist Tom Morello of Rage Against the Machine, bassist Martyn LeNoble, drummer Stephen Perkins, both from Jane's Addiction and Porno for Pyros, and keyboardist Matt Serletic. In November 1998, the group recorded the song for Robert Rodriguez's 1998 horror/sci-fi film The Faculty. A music video was also released. While the other members of the band were filmed specifically for the video, Staley's appearance consisted of footage pulled from Mad Season's 1995 Live at the Moore video. A song titled "Things You Do" featuring Staley on vocals was part of the soundtrack to the 2012 film Grassroots. In the film, the song was credited to "The Bondage Boys featuring Layne Staley", but the song had been credited to "Layne Staley and The Aftervibes" and "Layne Staley and Second Coming" when it leaked on the internet years before.
== Further reading == Reineccius, Gary (1998). Sourcebook of Flavors. Berlin: Springer. ISBN 978-0-8342-1307-4. Fennema, O.R., ed. (1985). Food Chemistry (2nd ed.). New York: Marcell Dekker, Inc. pp. 46–50. Bell, L.N.; Labuza, T.P. (2000). Practical Aspects of Moisture Sorption Isotherm Measurement and Use (2nd ed.). Egan, MN: AACC Egan Press.
As ETD is increasingly popular for protein and peptide structure analysis, implementation on easily available ion-trap mass spectrometers coupled with high resolution mass analyzers continues to evolve.
The Port of Hong Kong, located by the South China Sea, is a deepwater seaport dominated by trade in containerised manufactured products. A key factor in the economic development of Hong Kong, the natural shelter and deep waters of Victoria Harbour provide ideal conditions for berthing and the handling of all types of vessels. It is one of the busiest ports in the world, in the three categories of shipping movements, cargo handled, and passengers carried. This makes Hong Kong a Large-Port Metropolis. The Star Ferry operates two lines across Victoria Harbour for its 53,000 daily passengers. Ferries also serve outlying islands inaccessible by other means. Smaller kai-to boats serve the most remote coastal settlements. Ferry travel to Macau and mainland China is also available. Junks, once common in Hong Kong waters, are no longer widely available and are used privately and for tourism. The large size of the port gives Hong Kong the classification of Large-Port Metropolis.
In December 2022, Bukele tweeted that he believed that the country's 262 municipalities should be reduced to 50. He called it "absurd" ("absurdo") that El Salvador, around 8,100 square miles (21,000 km2) in size, had so many municipalities. Some lawyers and politicians criticized Bukele's proposed reduction as an attempt to consolidate power by gerrymandering. His allies supported the proposal, with some proposing a reduction in the number of Legislative Assembly seats. On 1 June 2023, during a speech commemorating his fourth year in office, Bukele announced that he would present two proposals to the Legislative Assembly. One sought to reduce the number of seats in the assembly from 84 to 60, and the other sought to reduce the number of municipalities from 262 to 44. Bukele justified the legislative reduction by saying that the legislature had 60 seats before the signing of the Chapultepec Peace Accords in 1992 that ended the Salvadoran Civil War, and the accords' only accomplishment was the addition of 24 seats to the legislature. About the municipal-reduction proposal, he stated that the 262 municipalities would retain their cultural identities and be classified as districts. The Legislative Assembly approved the proposal for legislative reductions on 7 June 2023, and approved the proposal for municipal reductions six days later. Both reductions became effective on 1 May 2024.
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.
Solutions are best kept cold, protected from light, and buffered to a pH that limits hydrolysis. Dividing a stock into single-use aliquots avoids repeated freeze-thaw cycles, which measurably reduce the intact parent peak over time.