If you have been reading about melanocortin receptor and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-06-29. Numbers and descriptions here follow the published literature rather than marketing material.
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-2 is frequently confused with afamelanotide, a linear analogue authorised in the European Union for erythropoietic protoporphyria. The two compounds differ in chain length, ring structure and receptor selectivity, so findings for one cannot be transferred directly to the other. Published controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports. Questions about effect size, dose-response behaviour and long-term safety therefore remain unresolved.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
| 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.
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.
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.
=== Proximal TCR signaling === Phosphorylated ITAMs in the cytoplasmic tails of CD3 recruit protein tyrosine kinase Zap70 that can bind to the phosphorylated tyrosine residues with its SH2 domain. This brings Zap70 into close proximity to Lck which results to its phosphorylation and activation by Lck. Lck phosphorylates a number of different proteins in the TCR pathway. Once activated, Zap70 is able to phosphorylate multiple tyrosine residues of the transmembrane protein LAT. LAT is a scaffold protein associated with the membrane. It itself does not have any catalytic activity but it provides binding sites for signalling molecules via phosphorylated tyrosine residues. LAT associates with another scaffolding protein Slp-76 via the Grap2 adaptor protein, which provides additional binding sites. Together LAT and Slp-76 provide a platform for the recruitment of many downstream signaling molecules. By bringing these signalling molecules into close proximity, they can then be activated by Lck, Zap70 and other kinases. Therefore, the LAT/Slp76 complex act as a highly cooperative signalosome. Molecules that bind the LAT/Slp76 complex include: Phospholipase Cγ1 (PLCγ1), SOS via a Grb2 adaptor, Itk, Vav, Nck1 and Fyb.
The basal surface of epithelial tissue rests on a basement membrane and the free, apical, or apex surface faces body fluid or the outside. The basement membrane acts as a scaffolding on which epithelium can grow and regenerate after injuries, and comprises the basal lamina and reticular lamina; although, some older sources use basement membrane and basal lamina synonymously. The basement membrane acts as a selectively permeable membrane that determines which substances will be able to enter the epithelium, as epithelial tissue has a nerve supply though no blood supply. There are three principal shapes of epithelial cell: squamous (scaly), columnar, and cuboidal. Transitional epithelium has cells that can change from squamous to cuboidal, depending on the amount of tension on the epithelium. Epithelial tissue can be further categorised as having a singular layer of cells as simple epithelium; or as layers of two or more cells deep as stratified epithelium—stratified squamous epithelium, stratified cuboidal epithelium, and stratified columnar epithelium. When taller simple columnar epithelial cells are viewed in cross section showing several nuclei appearing at different heights, they can be confused with stratified epithelia, and are thus termed as pseudostratified columnar epithelium. Epithelial cells are often ciliated. Stratified epithelia be further divided into keratinised, parakeratinised, and transitional epithelia or urothelia.
Macrophallism, macrophallus, or macropenis, is a condition defined in a medical context as an adult or juvenile penis with an erect length of 2.5 standard deviations (SD) above the average (approximately seven inches or 17.8 cm in length post-puberty) but otherwise formed normally. It is generally characterized by substantial penile girth or length, sometimes causing functional issues. The condition is occasionally associated with underlying conditions like priapism, palmar fibromatosis, hypertrophy, and sickle cell disease. Treatment for macrophallism is extremely uncommon, and only for when penetration isn't possible, but primarily include penis reduction.
=== Mass spectral quality === A key feature of this interface is to produce top quality EI spectra from compounds dissolved in a liquid phase. In this case, quality is intended as a measure of the degree of success in a virtual comparison with thousands of spectra stored in the electronic libraries. Identification capability in real-world applications, when peaks are small and noise is high, can be greatly influenced by the quality of ionization. A NIST library version 2.0d was used for comparison. In this case, identification capability is not compromised by the presence of solvent vapor residues and matching quality tops that of a typical GC-MS system.
== Composition == The PDL substance has been estimated to be 70% water, which is thought to have a significant effect on the tooth's ability to withstand stress loads. The completeness and vitality of the PDL are essential for the functioning of the tooth. The PDL ranges in width from 0.15 to 0.38mm with its thinnest part located in the middle third of the root. The width progressively decreases with age. The PDL is a part of the periodontium that provides for the attachment of the teeth to the surrounding alveolar bone by way of the cementum. The PDL appears as the periodontal space of 0.4 to 1.5 mm on radiographs, a radiolucent area between the radiopaque lamina dura of the alveolar bone proper and the radiopaque cementum.
Sources: en.wikipedia.org
Carbohydrates are usually present, often in a mix of simple sugars like glucose and more complex oligosaccharides such as maltodextrin which are supposed to provide more sustained energy. Carbohydrates cause an increase in serotonin levels. These are used both to provide a sweet taste and fuel for exercise, though evidence for whether they actually enhance exercise performance is mixed. Protein supplements, usually in a palatable powdered form such as whey protein or rice protein, are also commonly used both for flavour and as a fuel for muscle growth and recovery. Electrolytes providing sodium, potassium and magnesium (and often others such as zinc, calcium, iron etc in smaller amounts) are often included to replace those lost due to sweating during heavy exercise, generally as a mixture of different salts, sometimes including exotic forms such as zinc monomethionine aspartate or calcium fructoborate which are supposed to be better absorbed or have other special properties. Electrolytes help the body perform homeostasis and prevent dehydration. Nitrate salts are commonly included (often as "beetroot extract") for their supposed benefits for endurance exercise. Sometimes this is achieved by using nitrate salts of other ingredients (e.g. arginine nitrate, creatine nitrate). Creatine, a natural chemical created in the kidneys and liver, is used supposedly to improve physical performance. It also promotes an increase in muscle growth. β-Alanine is a common ingredient found in 87% of leading pre-workout formulas.
21,000, 5 November 2010 - The SENSEX closed at 21,004.96, for its first close above the 21,000 mark. It would take nearly three years for the index to make its next close above this level. 22,000, 24 March 2014 - The SENSEX closed at 22,055.48, for its first close above the 22,000 mark. For the first time, the SENSEX zoomed ahead of the Hang Seng Index. 23,000, 12 May 2014 - The SENSEX closed at 23,551.00, for its first close above the 23,000 mark, 24,000, 16 May 2014 - The SENSEX closed at 24,121.74, for its first close above the 24,000 mark, Breaking all previous records and above all other indexes in the world. 25,000, 5 June 2014 - The SENSEX closed at 25,019.51, for its first close above the 25,000 mark, 26,000, 7 July 2014 - The SENSEX closed at 26,123.55, for its first close above the 26,000 mark, 27,000, 2 September 2014 - The SENSEX closed at 27019.39, for its first close above the 27,000 mark, 28,000, 5 November 2014 - The SENSEX crossed 28,000 mark, on 5 November 2014. This is the seventh 1000-point milestone the index has crossed in 2014, breaking the six 1000-point record set in 2007.
"Absorption spectrum of melanin". Department of Computer Science and Technology. "Tyrosine metabolism—Reference pathway". Kyoto Encyclopedia of Genes and Genomes. Retrieved 13 June 2024. "Melanogenesis". Kyoto Encyclopedia of Genes and Genomes. Retrieved 13 June 2024.
Following the UDI, however, Rhodesia began to demonstrate that it had the potential to develop a greater degree of economic self-sufficiency. After the Rhodesian Front began introducing incentives accorded to domestic production, industrial output expanded dramatically. A rigid system of countermeasures enacted to combat sanctions succeeded in blunting their impact for at least a decade. Over the next nine years, Rhodesian companies, spiting the freezing of their assets and blocking of overseas accounts, also perfected cunning techniques of sanctions evasion through both local and foreign subsidiaries, which operated on a clandestine trade network. From 1968 until 1970, there was virtually no further dialogue between Rhodesia and the UK. In a referendum in 1969, white voters approved a new constitution and the establishment of a republic, thereby severing Rhodesia's last links with the British Crown, duly declared in March 1970. This changed immediately after the election of Edward Heath, who reopened negotiations. Smith remained optimistic that Heath would do his utmost to remedy Anglo-Rhodesian relations, although disappointed that he continued to adhere publicly to the original "five principles" proposed by Alec Douglas-Home, now foreign secretary.
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 cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.