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.
Last reviewed on 2026-07-15. Where a claim depends on a specific study, the study is described rather than over-claimed.
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controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports.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.
The peptide acts as a non-selective agonist at melanocortin receptors, showing affinity for MC1R, MC3R, MC4R and MC5R. Activation of MC1R on melanocytes drives the conversion of tyrosine into melanin and shifts production toward the darker eumelanin form. MC4R signalling in the central nervous system is linked to appetite and energy balance, which helps explain why reduced food intake appeared in early human studies. Effects on MC4R and on vascular tone also account for the erectile responses recorded as unexpected findings in those same trials.
Receptor binding at MC1R on melanocytes raises intracellular cyclic AMP and increases expression of tyrosinase and related enzymes. The downstream result is greater synthesis of eumelanin, the dark pigment, without ultraviolet exposure acting as the trigger. The compound is not selective, however, and also engages MC3R, MC4R and MC5R, which are expressed in the central nervous system and elsewhere. That lack of selectivity is the explanation usually offered for effects reported outside pigmentation, including appetite suppression and nausea. Selectivity remains a central theme in comparative studies of related peptides.
Human data remain limited and mostly short-term. Reports describe small trials and observational accounts rather than large controlled studies, so questions about dose-response relationships and long-term effects on melanocytes stay open. Whether repeated exposure alters naevus behaviour is not settled in the published record. Researchers also note that self-administered use outside clinical settings makes actual exposure difficult to quantify. Statements about efficacy and safety should therefore be read as preliminary rather than established.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Alpha-MSH analogue with a lactam ring |
| Molecular formula | C50H69N15O9 | Commonly cited value for the neutral peptide |
| Molecular weight | 1024.18 g/mol | Calculated for the free molecule |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water, DMSO and ethanol | Dissolution in pure water is often slow |
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.
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.
=== Production === Generators provide radiation shielding for transport and to minimize the extraction work done at the medical facility. A typical dose rate at 1 metre from 99mTc generator is 20–50 μSv/h during transport. These generators' output declines with time and must be replaced weekly, since the half-life of 99Mo is still only 66 hours. Since the half-life of the parent nuclide (99Mo) is much longer than that of the daughter nuclide (99mTc), 50% of equilibrium activity is reached within one daughter half-life, 75% within two daughter half-lives. Hence, removing the daughter nuclide (elution process) from the generator ("milking" the cow) is reasonably done as often as every 6 hours in a 99Mo/99mTc generator.
The iron storage disorder hereditary hemochromatosis (HHC) is an autosomal recessive genetic disorder that usually results from defects in this gene. The disease-causing genetic variant most commonly associated with hemochromatosis is p. C282Y. About 1/200 of people of Northern European origin have two copies of this variant; they, particularly males, are at high risk of developing hemochromatosis. This variant may also be one of the factors modifying Wilson's disease phenotype, making the symptoms of the disease appear earlier. Allele frequencies of HFE C282Y in ethnically diverse western European white populations are 5-14% and in North American non-Hispanic whites are 6-7%. C282Y exists as a polymorphism only in Western European white and derivative populations, although C282Y may have arisen independently in non-whites outside Europe. HFE H63D is cosmopolitan but occurs with greatest frequency in individuals of European descent. Allele frequencies of H63D in ethnically diverse western European populations are 10-29%. and in North American non-Hispanic whites are 14-15%. At least 42 mutations involving HFE introns and exons have been discovered, most of them in persons with hemochromatosis or their family members. Most of these mutations are rare. Many of the mutations cause or probably cause hemochromatosis phenotypes, often in compound heterozygosity with HFE C282Y. Other mutations are either synonymous or their effect on iron phenotypes, if any, has not been demonstrated.
Rhodesians made up an integral component of the Long Range Desert Group (LRDG), a mechanised reconnaissance and raiding unit formed in North Africa in 1940 to operate behind enemy lines. Initially made up of New Zealanders, the unit's first British and Rhodesian members joined in November 1940. It was reorganised several times over the next year as it expanded and by the end of 1941 there were two Rhodesian patrols: S1 and S2 Patrols, B Squadron. Each vehicle bore a Rhodesian place-name starting with "S" on the bonnet, such as "Salisbury" or "Sabi". From April 1941 the LRDG was based at Kufra in south-eastern Libya. The Rhodesians were posted to Bir Harash, about 160 kilometres (99 mi) to the north-east of Kufra, to patrol, hold the Zighen Gap and guard against a possible Axis attack from the north. For the next four months they lived in near-total isolation from the outside world, an exception coming in July 1941 when they and a group of airmen from No. 237 Squadron celebrated Rhodes Day together in the middle of the Cyrenaican desert. In November 1941 the British Eighth Army, commanded by General Cunningham, launched Operation Crusader in an attempt to relieve Tobruk. The British XXX Corps, led by the 7th Armoured Division ("the Desert Rats") with its Rhodesian platoons, would form the main body of attack, advancing west from Mersa Matruh, then sweeping around in a north-westerly direction towards Tobruk. The XIII Corps would concurrently advance north-west and cut off Axis forces on the coast at Sollum and Bardia.
=== Exercise recovery === In healthy adults, after exercise, vitamin E was shown to not have any benefits for post-exercise recovery, as measured by muscle soreness and muscle strength, or measured by indicators for inflammation or muscle damage, such as interleukin-6 and creatine kinase.
Sources: en.wikipedia.org
In 1953, scientists at the Sloan Kettering Institute in New York City demonstrated that cigarette tar painted on the skin of mice caused fatal cancers. This work attracted much media attention; the New York Times and Life both covered the issue. The Reader's Digest published an article entitled "Cancer by the Carton". On January 11, 1964, the United States Surgeon General's Report on Smoking and Health was published; this led millions of American smokers to quit, the banning of certain types of advertising, and required warning labels on tobacco products. These results were first widely accepted in the medical community and publicized among the general public in the mid-1960s. The medical community's resistance to the idea that smoking tobacco caused disease has been attributed to bias from nicotine-dependent doctors, the novelty of the adaptations needed to apply epidemiological techniques and heuristics to non-infectious diseases, and cigarette industry pressure. The harmful health effects of smoking have been significant for the development of the science of epidemiology. As the mechanism of carcinogenicity is radiomimetic or radiological, the effects are stochastic. Definite statements can be made only on the relatively increased or decreased probabilities of contracting a given disease. For a particular individual, it is impossible to definitively prove a direct causal link between exposure to a radiomimetic poison such as tobacco smoke and the cancer that follows; such statements can only be made at the aggregate population level.
== Other uses == Ghotuo language (ISO 639-3 code: AAA) Adopt-An-Alleyway Youth Empowerment Project, San Francisco, California AAA or 3A, the middle level of the Tourist Attraction Rating Categories of China
Torture and assassination of Gaddaffi – ABC News video U.S. Policy Towards Qaddafi from the Dean Peter Krogh Foreign Affairs Digital Archives Muammar Gaddafi collected news and commentary at Al Jazeera English The Muammar Gaddafi story at BBC Online Muammar Gaddafi collected news and commentary at The Guardian Muammar Gaddafi collected news and commentary at The New York Times 2009 UN Security council speech from Al jazeera (English) on YouTube
CTI (Capture The Intelligence) – Known in other games as Capture The Flag. Players have to pick up an object (usually a suitcase) and bring it to their designated capture area. The opposing team can shoot down the player carrying the object after which it will drop to the ground to be picked up by another player or left to respawn when it is not picked up for a certain amount of time. Once brought inside the team's capture area, the team receives reinforcements and/or point depending on the map. PS (Push) – Players have to control a series of areas (marked with flags) in a particular order to complete the map objective. On most maps, the areas are situated near both teams' spawn area and closer to the center on the map, usually counting between 3 and 5 control areas. Depending on the map, teams are rewarded with reinforcements for capturing an area which was neutral or controlled by the opposite team. Teams can also receive reinforcement penalties when the team does not control more than half of the control areas. When one team controls all the areas in the map, that team is rewarded with reinforcements and/or points. SD (Search & Destroy) – The map objective in SD maps is to destroy certain objects which are usually located near the opposing team's spawning area. Objects range from crates with ammunition and guns to trucks. Some objects can be destroyed by simply doing damage to it, while others have to be destroyed with a claymore mine. TC (Territorial Control) Teams are rewarded with points and/or reinforcements when they control certain areas.
===== Direct method ===== The first commercially successful decaffeination process was invented by German merchant Ludwig Roselius and co-workers in 1903, after Roselius observed that a consignment of coffee beans accidentally soaked in sea water had lost most of their caffeine content while losing little of their flavour. The process was patented in 1906, and involved steaming coffee beans with various acids or bases, then using benzene as a solvent to remove the caffeine. Coffee decaffeinated this way was sold as Kaffee HAG after the company name Kaffee Handels-Aktien-Gesellschaft (Coffee Trading Company) in most of Europe, as Café Sanka in France and later as Sanka brand coffee in the United States. Café HAG and Sanka are now worldwide brands of Kraft Foods.
Sources: en.wikipedia.org
=== Negative or counter selection === In order to increase the specificity of aptamers selected by a given SELEX procedure, a negative selection, or counter selection, step can be added prior to or immediately following target incubation. To eliminate sequences with affinity for target immobilization matrix components from the pool, negative selection can be used where the library is incubated with target immobilization matrix components and unbound sequences are retained. Negative selection can also be used to eliminate sequences that bind target-like molecules or cells by incubating the oligonucleotide library with small molecule target analogs, undesired cell types, or non-target proteins and retaining the unbound sequences.
Moore opposed Governor Hogan's decision to cancel the Red Line, and said during his 2022 gubernatorial campaign that he supported restarting the rail project. He also called for an "intermodal Red Line, that is built quickly, cost-effectively, and with community input on stops, disruptions, and impact on local businesses". In November 2022, Moore said he would support creating a regional transit authority for working on Baltimore-area transportation projects. In his first budget in January 2023, Moore proposed allocating $500 million toward unspecified transportation projects. When asked by the Capital Gazette if this money would be used for the Red Line, Moore said that he had spoken with federal officials about restarting the line and that he did not want to "start from scratch". He also said he planned to use federal funds and public-private partnerships in transportation projects, including the Purple and Red lines. The budget was amended to reduce this funding to $100 million, but also gave the governor the ability to tap the state's "rainy day" fund for an extra $100 million. On June 15, 2023, Moore announced that he would seek federal funding to restart efforts to build the Red Line. In April 2025, after riding the SCMaglev during a trade trip in Japan, Moore said that he supported a proposed maglev project connecting Washington, D.C. and Baltimore. After the Federal Railroad Administration cancelled grants toward studying a maglev train between Washington, D.C.
In contrast, some infectious agents such as the Feline leukemia virus, are able to withstand immune responses and are capable of achieving long-term residence within an individual host, whilst also retaining the ability to spread into successive hosts. Virulence refers to the ability of an organism to invade a host and cause disease. Virulence factors are molecules that enable bacteria to attach to and invade the host's cells. These factors can be secreted, featured on the membrane, or located inside the cell (cytosolic). Cytosolic factors help bacteria rapidly adapt their metabolic, physical, and structural characteristics. Membrane-bound factors help bacteria adhere to the host and avoid detection by the host's immune system. Secreted factors assist bacteria to overcome the body's innate and adaptive immune defenses. In extracellular threats, secreted factors work together to destroy host cells.
== Safety == DCC often causes rashes. In vivo dermal sensitization studies according to OECD 429 confirmed DCC is a strong skin sensitizer, showing a response at 0.03 wt% in the Local Lymph Node Assay (LLNA) placing it in Globally Harmonized System of Classification and Labelling of Chemicals (GHS) Dermal Sensitization Category 1A. Thermal hazard analysis by differential scanning calorimetry (DSC) shows DCC poses minimal explosion risks.
== Slang terms == Some slang terms for opium include: "Big O", "Shanghai Sally", "dope", "hop", "midnight oil", "O.P.", and "tar". "Dope" and "tar" can also refer to heroin. The traditional opium pipe is known as a "dream stick". The term dope entered the English language in the early nineteenth century, originally referring to viscous liquids, particularly sauces or gravy. It has been used to refer to opiates since at least 1888, and this usage arose because opium, when prepared for smoking, is viscous.
Sources: en.wikipedia.org
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.
No national medicines agency has approved melanotan-2 for clinical use. Afamelanotide, a related but distinct peptide, holds a marketing authorisation in the European Union for a rare photosensitivity disorder. Melanotan-2 itself is handled as a laboratory chemical.
Its broad activity across melanocortin receptors makes it a tool for probing pigmentation, appetite and vascular signalling. Early trials recorded skin darkening and other effects that were not the original focus of the work. Those observations generated hypotheses that later studies have examined.
It is a synthetic cyclic heptapeptide and a non-selective melanocortin receptor agonist. Structurally it is modelled on alpha-melanocyte-stimulating hormone, a peptide that occurs naturally in the body.