alpha-MSH raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Cyclic heptapeptide, C-terminally amidated |
| Approximate molecular mass | 1024 Da | Monoisotopic mass of the free peptide |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility class | Soluble in water and polar solvents | Also dissolves in neutral aqueous buffer |
| Common synonyms | Melanotan II, MT-II, MT-2 | Described as a melanocortin agonist in early literature |
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.
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.
Research interest has centred on photoprotection and pigmentation, with a smaller body of work on appetite and sexual function. Published human data remain limited to small, frequently uncontrolled studies, and the compound has never received marketing approval from a national medicines regulator. Most laboratory work treats it as a pharmacological tool for probing melanocortin signalling in cell culture or animal models. Whether pigmentation changes observed in people translate into measurable protection against ultraviolet-induced DNA damage remains an open question.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, the naturally occurring peptide involved in pigmentation signalling. Its sequence is conventionally written as Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, with a lactam bridge joining the aspartate side chain to the lysine side chain. The empirical formula is C50H69N15O9 and the monoisotopic mass lies near 1023.5 daltons. N-terminal acetylation and the D-configured phenylalanine both increase resistance to enzymatic breakdown compared with the parent hormone.
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.
When Anna asserts her reputation of being a pessimist about love, Ariadne tells her that she will win her back. Grace emerges from the shadows and she and Lucie talk about resurrecting Jesse. Magnus Bane finds Matthew feeling desolate, as he notices the younger boy looking towards James and Cordelia dancing merrily. It is then that he reveals his attraction towards Cordelia and hints about the false marriage. Magnus is intrigued and decides that he needed to stay in London for a little while longer. Cordelia reflects on how drastically her life had changed since her arrival in London. James talks to her and tells her that he wishes she could be happy. He also states that the events of the whispering room had been a pretense. Cordelia is saddened but resolves to spend this one year with James happily. Meanwhile, in Chiswick manor, Tatiana, who is now being banished to the Adamant Citadel, visits her son's coffin. She finds Belial waiting for her, and he says that he will rise much earlier than the Nephilim assumed. He also states that since Tatiana was now in the Adamant Citadel, they will strike at the heart of the Shadowhunters - their Adamas. Saying this he vanishes again, leaving Tatiana satisfied.
=== Bjerknes feedback === The close relationship between ocean temperatures and the strength of the trade winds was first identified by Jacob Bjerknes in 1969. Bjerknes also hypothesized that ENSO was a positive feedback system where the associated changes in one component of the climate system (the ocean or atmosphere) tend to reinforce changes in the other. This process is known as Bjerknes feedback. For example, during the growth of El Niño, the reduced contrast in ocean temperatures across the Pacific results in weaker trade winds, further reinforcing the El Niño state. Although these associated changes in the ocean and atmosphere often occur together, the state of the atmosphere may resemble a different ENSO phase than the state of the ocean or vice versa. Because their states are closely linked, the variations of ENSO may arise from changes in both the ocean and atmosphere and not necessarily from an initial change of exclusively one or the other. Conceptual models explaining how ENSO operates generally accept the Bjerknes feedback hypothesis. However, ENSO would perpetually remain in one phase if Bjerknes feedback were the only process occurring. Several theories have been proposed to explain how ENSO can change from one state to the next despite the positive feedback. These explanations broadly fall under two categories. In one view, the Bjerknes feedback naturally triggers negative feedbacks that end and reverse the abnormal state of the tropical Pacific.
The radioactive decay constant, the probability that an atom will decay per year, is the solid foundation of the common measurement of radioactivity. The accuracy and precision of the determination of an age (and a nuclide's half-life) depends on the accuracy and precision of the decay constant measurement. The in-growth method is one way of measuring the decay constant of a system, which involves accumulating daughter nuclides. Unfortunately for nuclides with high decay constants (which are useful for dating very old samples), long periods of time (decades) are required to accumulate enough decay products in a single sample to accurately measure them. A faster method involves using particle counters to determine alpha, beta or gamma activity, and then dividing that by the number of radioactive nuclides. However, it is challenging and expensive to accurately determine the number of radioactive nuclides. Alternatively, decay constants can be determined by comparing isotope data for rocks of known age. This method requires at least one of the isotope systems to be very precisely calibrated, such as the Pb–Pb system.
== External links == Apelin+protein,+human at the U.S. National Library of Medicine Medical Subject Headings (MeSH) "Apelin". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology. Archived from the original on 2021-08-16. Retrieved 2007-10-25. Human APLN genome location and APLN gene details page in the UCSC Genome Browser.
is large, which results in a larger plastic radius. This implies that the material can plastically deform, and, therefore, is tough. This estimate of the size of the plastic zone beyond the crack tip can then be used to more accurately analyze how a material will behave in the presence of a crack. The same process as described above for a single event loading also applies and to cyclic loading. If a crack is present in a specimen that undergoes cyclic loading, the specimen will plastically deform at the crack tip and delay the crack growth. In the event of an overload or excursion, this model changes slightly to accommodate the sudden increase in stress from that which the material previously experienced. At a sufficiently high load (overload), the crack grows out of the plastic zone that contained it and leaves behind the pocket of the original plastic deformation. Now, assuming that the overload stress is not sufficiently high as to completely fracture the specimen, the crack will undergo further plastic deformation around the new crack tip, enlarging the zone of residual plastic stresses. This process further toughens and prolongs the life of the material because the new plastic zone is larger than what it would be under the usual stress conditions. This allows the material to undergo more cycles of loading. This idea can be illustrated further by the graph of Aluminum with a center crack undergoing overloading events.
Sources: en.wikipedia.org
"Generalized pain, defined as pain in at least 4 of 5 regions, is present." "Symptoms have been present at a similar level for at least 3 months." "Widespread pain index (WPI) ≥ 7 and symptom severity scale (SSS) score ≥ 5 OR WPI of 4–6 and SSS score ≥ 9." "A diagnosis of fibromyalgia is valid irrespective of other diagnoses. A diagnosis of fibromyalgia does not exclude the presence of other clinically important illnesses."
Cement may be created using a countercurrent kiln where the heat is passed in the cement and the exhaust combined, while the incoming air draft is passed along the two, absorbing the heat and retaining it inside the furnace, finally reaching high temperatures. Gasification: the process of creating methane and carbon monoxide from organic or fossil matter, can be done using a counter-current fixed bed ("up draft") gasifier which is built in a similar way to the Anagama kiln, and must therefore withstand more harsh conditions, but reaches better efficiency. In nuclear power plants, water leaving the plant must not contain even trace particles of Uranium. Counter Current Decantation (CCD) is used in some facilities to extract water, totally clear of Uranium.
== Forms and nomenclature == There are two forms or enantiomers of aspartic acid. The name "aspartic acid" can refer to either enantiomer or a mixture of two. Of these two forms, only one, "L-aspartic acid", is directly incorporated into proteins. The biological roles of its counterpart, "D-aspartic acid" are more limited. Where enzymatic synthesis will produce one or the other, most chemical syntheses will produce both forms, "DL-aspartic acid", known as a racemic mixture.
is the modified Bessel function of the second kind. For the situation where the asperities on the two surfaces have a Gaussian height distribution and the peaks can be assumed to be spherical, the average contact pressure is sufficient to cause yield when
Sources: en.wikipedia.org
Initially, there may be a small ulcer in the mouth which progresses into necrotizing gingivitis – painful bleeding of the gums and inter-dental papillae. This is followed by a rapid spread of the infection resulting in more general inflammation of the mouth and lips, facial edema, and foul breath. If untreated, within a few days the necrotizing infection progresses into the facial muscles, the skin, and the upper and lower jaw resulting in tissue destruction and sloughing. Many patients die due to sepsis; survivors are left with permanent scarring and disfigurement. Noma neonatorum is a severe infection affecting very young or newborn children in impoverished environments. A gangrenous infection spreads across the oral, nasal, and/or anal areas, and is frequently fatal. The pattern of lesions is similar to those found in noma. The World Health Organization divides noma into five stages: Acute necrotizing gingivitis, edema, gangrenous, scarring, and sequelae.
The longest word, hippopotomonstrosesquippedaliophobie (36 letters) is the fear (or phobia) of long words. The word is formed from the Latin word sesquipedalia (singular sesquipedalis), which the Ancient Roman poet Horace used in Ars Poetica to describe excessively long words; literally, it means "a foot-and-a-half long". Like the other phobias in the list, hippopotomonstrosesquippedaliophobie can be pluralised by adding the letter s to the end. The adjective interdépartemental (18 letters), which also appears in the list, can be made longer by appending the letters es, which gives its plural, grammatically gendered form.
== Background == Founded in 1989 by Jaba Ioseliani, the Mkhedrioni presented itself as the heir to historic Georgian guerrilla groups who fought Iranian and Ottoman occupiers. The group's name literally means "horsemen", but in Georgian it has a meaning closer to "knights" (this alternative translation has occasionally been used). Each member of the organization would take an oath to defend Georgia's people, the Georgian Orthodox and Apostolic Church and Georgia's land, and wore a medallion with a scene of Saint George slaying the dragon on one side and the bearer's name and blood type on the other. The establishment of the Mkhedrioni took place as Georgia moved towards independence in the final years of the Soviet Union. Relations between Georgian nationalists and the country's national minorities, especially the Abkhaz and Ossetians, were difficult at best even during Soviet rule and grew more tense during the rise to power of the nationalist dissident Zviad Gamsakhurdia. The Mkhedrioni was one of a number of nationalist paramilitary groups established during this period as a counterbalance to similar paramilitary organisations set up by rival nationalists elsewhere in Georgia. The Mkhedrioni's members gained an unpleasant reputation as heavily armed thugs who engaged in violent intimidation of their rivals. They were highly visible, wearing what amounted to a uniform of jeans, sweaters and jackets, topped off by sunglasses (even worn indoors). Leaders wore Armani suits bulging with guns, according to one author.
Niels Lund Chrestensen (9 August 1940 – 16 August 2025) was a German businessman and plant breeder. He was a recipient of the Order of Merit of the Federal Republic of Germany (1999). Chrestensen died on 16 August 2025, in Erfurt, Thuringia, at the age of 85.
One prominent case was the classification of ascolichen families by the structure of the ascus apex (the tip of the spore sac). Josef Hafellner (1984) reorganized many ascolichen families by ascus-apex staining (amyloid ring present vs. absent), treating that feature as primary. Later DNA work found several of those families to be polyphyletic: the ascus type had arisen independently in unrelated lineages. The results echoed Nylander's century-old warning against single-trait taxonomy. Leif Tibell (1998) urged that robust taxa rest on multiple, independent characters. Pier Luigi Nimis (1998) warned that elevating every apparent clade to genus rank risks "explosive inflation" and listed five tests—monophyly, formal analysis, ≥ 1 diagnostic trait, broad sampling, and demonstrable informational gain—before renaming species. Where those tests are not met, Nimis advised using subgeneric rank so that binomials remain stable. Tibell further separated goals: classification should provide a stable, useful scheme, whereas phylogeny seeks the full branching pattern. He argued that constant renaming for every new tree can undermine nomenclatural stability; revisions should await strong, multi-line evidence. These philosophical perspectives influenced how lichenologists handled emerging molecular results a few years later. By the late 1990s lichenologists, trained in data matrices and synapomorphy logic, were ready to fold DNA data into taxonomy.
Sources: en.wikipedia.org
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.
Afamelanotide is the linear analogue [Nle4-D-Phe7]-alpha-MSH, sometimes called melanotan I, while melanotan II is cyclic and carries three further substitutions. The two are distinct molecules and are not interchangeable in analytical testing.
Binding to the four melanocortin receptor subtypes is well documented in vitro. The relative contribution of each subtype to whole-body effects in humans is far less certain.
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.