melanocortin receptor is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2026-04-13. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Melanotan-2 is a synthetic peptide designed as an analog of alpha-melanocyte-stimulating hormone, a signaling molecule produced in the pituitary and skin. Its structure is a linear chain of seven amino acids that folds into a ring through an internal lactam bridge joining two side chains. The compound is sometimes written as MT-II or MEL-2 in informal and commercial contexts. It belongs to the melanocortin peptide family, a group of short signaling molecules that share a conserved core sequence recognized by melanocortin receptors.
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.
| 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 |
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.
No regulatory authority has approved melanotan-2 for human use, and several countries classify it as a prescription-only or controlled substance, which restricts lawful supply. Material sold online is generally labelled as a research chemical and is not required to meet pharmaceutical standards of identity or purity. Published human data consist mainly of small uncontrolled studies, case reports and adverse-event notifications, so the evidence base is descriptive rather than confirmatory. Whether repeated melanocyte stimulation alters long-term naevus behaviour remains an open question that no completed trial has resolved.
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.
Published human data come mostly from small, short studies rather than large controlled trials. Reported outcomes include increased skin pigmentation and, in some reports, effects on appetite and libido, but sample sizes are small and follow-up is limited. Whether long-term use produces durable pigment changes or adverse effects is not established. Because products sold outside pharmacies are not standardized, the actual content of any given vial is often unknown. Independent testing of such material is uncommon.
Melanotan II is a synthetic cyclic heptapeptide analog derived from the core sequence of alpha-melanocyte-stimulating hormone. Researchers at the University of Arizona synthesized it during the 1980s while studying pigmentation and appetite signaling. The compound is not an approved medicine in any major jurisdiction and appears mainly in laboratory and research-chemical settings. Its structure incorporates a lactam bridge between side chains, which constrains the ring and slows enzymatic breakdown relative to the natural 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.
=== Government === Government – Official website of Government of Malaysia National Palace – official website of the king of Malaysia Prime Minister – official website of the prime minister of Malaysia Parliament – official website of Parliament of Malaysia Federal Court Archived 18 July 2025 at the Wayback Machine – official website of the Chief Registrar of the Federal Court of Malaysia Statistics – official website of the Department of Statistics Malaysia
To Friar John Cor, by order of the King, to make aqua vitae, VIII bolls of malt. The Exchequer Rolls' record crown income and expenditure and the quote records eight bolls of malt given to Friar John Cor to make aqua vitae over the previous year. The term aqua vitae is Latin for "water of life" and was the general term for distilled spirits. This would be enough for 1,500 bottles, which suggests that distillation was well-established by the late 15th century. The first known reference to a still for making "aquavite" in Scotland appears in the Aberdeen council registers, in a case heard in 1505 by the town's bailies concerning the inheritance of goods belonging to a chaplain named Sir Andrew Gray, who died in 1504. Among his goods was recorded (in Middle Scots) "ane stellatour for aquavite and ros wattir'". Aqua vitae (in the form of wine or spirits) was used when making gunpowder to moisten the slurry of saltpetre, charcoal and sulphur. As a drink, Scotch whisky was a favourite of King James IV of Scotland. Spirit production was first taxed by the Parliament of Scotland from January 1644, with an excise duty of 2s 8d imposed per Scots pint; instigating the illicit distilling of spirits within the country. Between the 1760s and the 1830s, a substantial unlicensed trade originated from the Highlands, forming a significant part of the region's export economy. In 1782, more than 1,000 illegal stills were seized in the Highlands: these can only have been a fraction of those in operation.
==== Left 4 Dead branch ==== The Left 4 Dead branch is an overhaul of many aspects of the Source engine through the development of the Left 4 Dead series. Multiprocessor support was further expanded, allowing for features like split screen multiplayer, additional post-processing effects, event scripting with Squirrel, and the highly-dynamic AI Director. The menu interface was re-implemented with a new layout designed to be more console-oriented. This branch later fueled the releases of Alien Swarm and Portal 2, the former released with source code outlining many of the changes made since the branch began. Portal 2, in addition, served as the result of Valve taking the problem of porting to PlayStation 3 in-house, and in combination with Steamworks integration creating what they called "the best console version of the game".
However, the degree of fractionation is not necessarily consistent between organisms, complicating the determination of paleosalinity with this method. There also appears to be a negative correlation between growth rate and fractionation in these coccolithophores. Further experiments on unicellular algae Eudorina unicocca and Volvox aureus show no effect of growth rate (controlled by nitrogen limitation) on fatty acid δD. However, sterols become more D-depleted as growth rate increases, in agreement with alkenone isotopic composition in coccolithophores. Overall, although there are some strong trends with lipid δD, the specific fractionations are compound-specific. As a result, any attempt to create a salinometer through δD measurements will necessarily be specific to a single compound type.
It was in this context that the European Parliament elections of June 1994 occurred, in which the People's Party for the first time surpassed the PSOE in number of votes ─ it obtained 40% of the suffrages against 30% for the Socialists ─ which led them to demand the holding of general elections and to ask for the resignation of Felipe González. A month before the European elections, Judge Baltasar Garzón, who had been "number two" on the Socialist lists for Madrid, had left his seat in Parliament and the post of Government Delegation for the National Plan on Drugs, and had immediately reopened the GAL case. Shortly afterwards, several high-ranking officials of the socialist administration and the PSOE (Julián Sancristóbal, Rafael Vera and Ricardo García Damborenea) were arrested for their alleged participation in the kidnapping and frustrated murder of the French citizen Segundo Marey. As the former Minister of the Interior José Barrionuevo, a Socialist deputy, was also implicated, Garzón had to pass the "Marey case" to the Supreme court and Judge Eduardo Moner took charge of the investigation, who in January 1996 also charged Barrionuevo. A year before, another big scandal related to the "dirty war" against ETA had been uncovered. On that date the Civil Guard general Enrique Rodríguez Galindo was arrested for his alleged involvement in the "Lasa and Zabala case", the kidnapping and subsequent murder of José Antonio Lasa and José Ignacio Zabala, alleged members of ETA.
Sources: en.wikipedia.org
== Operations == KCI is composed of three business units: Active Healing Solutions, LifeCell and Therapeutic Support Systems, that operate in the wound care, regenerative medicine and therapeutic support systems markets. The largest of these business units is dedicated to wound care primarily negative pressure wound therapy for the treatment of traumatic wounds, pressure ulcers, chronic wounds and diabetic ulcers but also assistance with surgery. The therapeutic support systems developed and supplied by KCI are largely for the treatment and prevention of complications associated with patient immobility. These include support surfaces for hospital beds and home patients designed to address pulmonary complications in immobile patients. KCI also develops specialty beds for use in hospitals or in long-term care facilities. KCI expanded into the regenerative medicine market in 2008. Through subsidiary company LifeCell Corporation, KCI develops and supplies tissue-based products. These include tissue-based treatments used in surgical procedures to repair soft-tissue.
=== Multilayer approaches === In the case of Multi-layer flat textiles where one or more layer(s) remains sturdy an overlay fabric can be used to secure the damaged layer(s) to an undamaged layer when the weakened layer(s) are separated from the sturdy layer(s), a full backing sewn or adhesive should be used to reattach it. Disassembly is avoided as it requires the removal of original stitching.
He also stated that the novel "historicizes and theorizes animal life and death," and that it demonstrates the ways that symbolism and materiality of meat are "co-opted within patriarchal political structures," putting it in the same space as theorists like Carol J. Adams, Donna J. Haraway, Laura Wright, and Cary Wolfe, and writers such as J. M. Coetzee. In 1997, S. Reneé Wheeler wrote in the Vegetarian Journal, saying that "finding books with vegetarian themes" is important for helping children "feel legitimate in being vegetarian." In 2004, writer J. M. Coetzee argued that since the "mode of consciousness of nonhuman species is quite different from human consciousness," it is hard for writers to realize this for animals, with a "temptation to project upon them feelings and thoughts that may belong only to our own human mind and heart," and stated that reviewers have ignored the presence of animals in his books. He also stated that animals are present in his "fiction either not at all or in a merely subsidiary role" because they occupy "a subsidiary place in our lives" and argued that it is not "possible to write about the inner lives of animals in any complex way." In 2014, The New Yorker published a short story by Jonathan Lethem titled "Pending Vegan" which follows "one family, a husband and wife and their four-year-old twin daughters" on a trip to SeaWorld in San Diego, California.
When bound in the active site of an oxidoreductase, the nicotinamide ring of the coenzyme is positioned so that it can accept a hydride from the other substrate. Depending on the enzyme, the hydride donor is positioned either "above" or "below" the plane of the planar C4 carbon, as defined in the figure. Class A oxidoreductases transfer the atom from above; class B enzymes transfer it from below. Since the C4 carbon that accepts the hydrogen is prochiral, this can be exploited in enzyme kinetics to give information about the enzyme's mechanism. This is done by mixing an enzyme with a substrate that has deuterium atoms substituted for the hydrogens, so the enzyme will reduce NAD+ by transferring deuterium rather than hydrogen. In this case, an enzyme can produce one of two stereoisomers of NADH. Despite the similarity in how proteins bind the two coenzymes, enzymes almost always show a high level of specificity for either NAD+ or NADP+. This specificity reflects the distinct metabolic roles of the respective coenzymes, and is the result of distinct sets of amino acid residues in the two types of coenzyme-binding pocket. For instance, in the active site of NADP-dependent enzymes, an ionic bond is formed between a basic amino acid side-chain and the acidic phosphate group of NADP+. On the converse, in NAD-dependent enzymes the charge in this pocket is reversed, preventing NADP+ from binding.
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.
It is a synthetic seven-amino-acid peptide modeled on alpha-melanocyte-stimulating hormone. It carries two non-natural substitutions and a cyclic bridge that increase its stability relative to the natural hormone. It circulates as a research chemical and is not an approved medicine.