This is a working overview of MC1R, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-02-01 and is reviewed periodically as new material appears.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms differ |
| Molecular weight | Approximately 1024 g/mol | Calculated for the free base |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water and polar solvents | Poorly soluble in non-polar solvents |
| Typical storage | -20 degrees Celsius, dry, protected from light | Refers to the solid form |
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.
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.
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.
On November 16, 2004, Valve released Half-Life 2. The game had a six-year development cycle, which saw several delays and the leak of the game's source code in October, 2003. Half-Life 2 returns the player to the role of Gordon Freeman. Set twenty years after the original game, Earth has been occupied by the Combine, a transdimensional race that exploited the events of the first game to invade. The G-Man inserts Freeman into City 17 in Eastern Europe to combat the Combine occupation. Considered one of the greatest video games of all time, Half-Life 2 was praised for its advances in computer animation, sound, narration, computer graphics, artificial intelligence and physics, and won more than 35 Game of the Year awards. Half-Life 2 was the first game to use Valve's Steam content delivery system, a system that eventually led to Valve falling out with publisher Sierra Entertainment.
These glands are termed Von Ebner's glands which have also been shown to have another function in the secretion of histatins which offer an early defense (outside of the immune system) against microbes in food, when it makes contact with these glands on the tongue tissue. Sensory information can stimulate the secretion of saliva providing the necessary fluid for the tongue to work with and also to ease swallowing of the food.
A recent method for the delivery of anti-angiogenesis factors to tumor regions in cancer patients uses genetically modified bacteria that are able to colonize solid tumors in vivo, such as Clostridium, Bifidobacteria and Salmonella by adding genes for anti-angiogenic factors such as endostatin or IP10 chemokine and removing any harmful virulence genes. A target can also be added to the outside of the bacteria so that they are sent to the correct organ in the body. The bacteria can then be injected into the patient and they will locate themselves to the tumor site, where they release a continual supply of the desired drugs in the vicinity of a growing cancer mass, preventing it from being able to gain access to oxygen and ultimately starving the cancer cells. This method has been shown to work both in vitro and in vivo in mice models, with very promising results. It is expected that this method will become commonplace for treatment of various cancer types in humans in the future.
Petroleum in some form has been used since ancient times. More than 4,300 years ago, bitumen was mentioned when the Sumerians used it to make boats. A tablet of the legend of the birth of Sargon of Akkad mentions a basket which was closed by straw and bitumen. More than 4,000 years ago, according to Herodotus and Diodorus Siculus, asphalt (bitumen) was used in the construction of the walls and towers of Babylon; there were oil pits near Ardericca and Babylon and a pitch spring on Zakynthos. In Babylon, petroleum was used for road construction, ship caulking, and medicine. The use of petroleum in ancient China dates back more than 2,000 years. The I Ching, one of the earliest Chinese writings, cites that oil in its raw state, without refining, was first discovered, extracted, and used in China in the 1st century BCE. In addition, the Chinese were the first to record the use of petroleum as fuel as early as the 4th century BCE. By 347 CE, oil was produced from bamboo-drilled wells in China. In the 7th century, petroleum was among the essential ingredients for Greek fire, an incendiary projectile weapon that was used by Byzantine Greeks against Arab ships attacking Constantinople. Crude oil was distilled by Persian chemists, with clear descriptions given in Arabic handbooks such as those of Abu Bakr al-Razi. In the 9th century, oil fields were exploited in the area around modern Baku, Azerbaijan. These fields were described by Abu Bakr al-Razi in the 10th century and by Marco Polo in the 13th century, who describes the output of those wells as hundreds of shiploads.
Sources: en.wikipedia.org
=== High aldosterone levels === Spironolactone is used in the treatment of hyperaldosteronism (high aldosterone levels or mineralocorticoid excess), for instance primary aldosteronism (Conn's syndrome). Antimineralocorticoids including spironolactone and eplerenone are first-line treatments for hyperaldosteronism. They improve blood pressure and potassium levels, as well as left ventricular hypertrophy, albuminuria, and carotid intima-media thickness, in people with primary aldosteronism. In people with hyperaldosteronism due to unilateral aldosterone-producing adrenocortical adenoma, adrenalectomy should be preferred instead of antimineralocorticoids. Spironolactone should not be used to treat primary aldosteronism in pregnancy due to its antiandrogen-related risk of teratogenicity in male fetuses.
=== 10 May === Russian artillery struck Vovchansk in Kharkiv Oblast killing one person, according to Governor Oleh Syniehubov. Three others were injured in shelling across the region. The governors of Voronezh and Kursk Oblasts in Russia said that three drones were shot down by anti-aircraft defenses, with debris from one drone damaging a pipeline in Kursk. According to the Governor, Alexander Bogomaz, a Russian military enlistment office was damaged in Bryansk Oblast. An attack on a training ground in Voronezh Oblast wounded at least fourteen soldiers. Yoshimasa Hayashi, Minister for Foreign Affairs of Japan, announced that Japan was in talks with NATO to set up a NATO liaison office at Tokyo, citing the Russian invasion of Ukraine and its threat to global stability. According to him, the liaison office would send a message to nations near Japan that "Japan is engaging in a very steady manner with NATO". Czech President Petr Pavel, in a radio interview, offered the Aero L-159 ALCA to Ukraine, subject to a decision by the Czech government. They carry an array of western weapons that Ukrainian is already using and is also a descendant of the Aero L-39 Albatros that the Ukraine Air Force currently uses.
=== Antidote to heparin === Protamine sulfate has been given to counteract the anticoagulant effect of heparin (1 mg per 100 units of heparin that had been given over the past 6 hours). It may be used in those who overdose on heparin or to reverse heparin's effect when it is no longer needed.
=== Detection in biological fluids === U-47700 may be measured in serum, plasma, blood or urine to monitor for abuse, confirm a diagnosis of poisoning, or assist in a medicolegal death investigation. Serum or blood U-47700 concentrations are expected to be in a range of 10–250 μg/L in intoxicated patients and 100–1,500 μg/L in deceased victims of acute overdosage. The detection usually involves analysis by liquid chromatography-mass spectrometry.
== Remote monitoring and control == Modern refrigerated containers are often equipped with a telematic control unit and a GPS tracking unit that enables remote monitoring of the container's parameters as part of a fleet telematics system. This integration is part of the fleet digitalization of the logistics industry, making the container an element of a larger Vehicle tracking system. The system allows a fleet management operator to track the container's location and monitor internal parameters such as temperature, humidity, and door status. This continuous stream of telemetry provides a complete track and trace record of the container's temperature throughout its journey, which helps ensure the integrity of the cold chain. If the temperature deviates from the set point, the system can send an automatic alert to the operator, allowing for immediate intervention. These systems also allow for remote control, enabling an operator to change the temperature settings or turn the refrigeration unit on or off from a central software platform.
Sources: en.wikipedia.org
Within Contact and Special Circumstances, there are also inner circles that can take control in crises, somewhat contradictory to the ideal notions of democratic and open process the Culture espouses. Contact and Special Circumstances may suppress or delay the release of information, for example to avoid creating public pressure for actions they consider imprudent or to prevent other civilisations from exploiting certain situations. In dealing with less powerful regressive civilisations, the Culture usually intervenes discreetly, for example by protecting and discreetly supporting the more liberal elements, or subverting illiberal institutions. For instance, in Use of Weapons, the Culture operates within a less advanced illiberal society through control of a business cartel which is known for its humanitarian and social development investments, as well as generic good Samaritanism. In Excession, a sub-group of Minds conspires to provoke a war with the extremely sadistic Affront, although the conspiracy is foiled by a GSV that is a deep cover Special Circumstances agent. Only one story, Consider Phlebas, pits the Culture against a highly illiberal society of approximately equal power: the aggressive, theocratic Idirans. Though they posed no immediate, direct threat to the Culture, the Culture declared war because it would have felt useless if it allowed the Idirans' ruthless expansion to continue. The Culture's decision was a value-judgement rather than a utilitarian calculation, and the "Peace Faction" within the Culture seceded.
==== Enzymatic methods ==== Bilirubin can be detected based on oxidation of bilirubin to biliverdin by bilirubin oxidase. At pH near 8 in presence of sodium cholate and sodium dodecylsulfate, both conjugated and unconjugated fractions are oxidised to biliverdin, which is then oxidised to purple then colourless products. The unconjugated fraction can be measured alone at pH 3.7 to 4.5, where bilirubin oxidase only oxidises unconjigated bilirubin. At pH 10 bilirubin oxidase preferentially oxidises conjugated bilirubin. Assays can thereby be taylored to detection of the specific bilirubin fractions by fine-tuning pH. These methods show good agreement with the Jendrassik-Grof method.
== Reconstructing developmental trajectories == Single-cell transcriptomic assays have allowed reconstruction development trajectories. Branching of these trajectories describes cell differentiation. Various methods have been developed for reconstructing branching developmental trajectories from single-cell transcriptomic data.. A comprehensive benchmarking of merhods can be found here. They use various advanced mathematical concepts from optimal transportation to principal graphs. and Hodge Laplacians. Some software libraries for reconstruction and visualization of lineage differentiation trajectories are freely available online.
== Adverse Effects == VEGF inhibitors in the treatment of cancer often cause adverse effects. Treatment with VEGF inhibitors suppresses cellular signalling pathways that are important in microvasculature regulation and maintenance. The effects on normal organs can then lead to vascular disturbances and regression of blood vessels. FDA has approved three drugs, bevacizumab, sunitinib and sorafenib, that were developed for antiangiogenic actions and are used in the treatment of patients with specific cancer types. All of these drugs have the mechanism of inhibiting VEGF signalling by blocking either the function of the VEGF ligand or VEGF receptor. Bevacizumab is a function-blocking monoclonal antibody that binds selectively to VEGF. Generally it is well tolerated and safe but can have adverse effects which can be intensified by chemotherapeutic agents used at the same time. For bevacizumab the most common adverse effects are hypertension, epistaxis, proteinuria, upper respiratory infection, stomatitis, diarrhea or other symptoms from the gastrointestinal tract as well as dyspnea, fatigue and dermatitis. Serious adverse effects connected to bevacizumab are infrequent but among those listed are gastrointestinal perforation, arterial thromboembolic events, hypertensive crisis, neutropenia, complications with wound healing, haemorrhage, nephrotic syndrome, heart failure and reversible posterior leukoencephalopathy syndrome. Sunitinib is a small molecule inhibitor which inhibits phosphorylation of VEGF receptor among other receptors. Sunitinib is mostly well tolerated.
Sources: en.wikipedia.org
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.
Both are synthetic analogues derived from the same parent hormone. Reference descriptions usually characterise afamelanotide as more selective for the MC1R subtype, whereas melanotan-2 is reported to interact with a wider range of melanocortin receptors.
Early studies explored melanocortin signalling and pigmentation, which later led to informal use of the label tanning peptide. That label is not a regulatory category and does not imply approved status for any purpose.
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.