A practical reference on MC1R: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-11-25 and is reviewed periodically as new material appears.
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.
Melanocytes are the pigment-producing cells of the skin, and they carry melanocortin-1 receptors on their surface. When the receptor is activated, cyclic adenosine monophosphate rises inside the cell and raises the activity of enzymes such as tyrosinase, which increases melanin output. Melanotan-2 binds melanocortin-1 receptors in vitro and in animal models, and this binding is generally described as the basis for the tanning effect. Other receptors account for different effects: melanocortin-4 receptors contribute to appetite and erectile signalling, while melanocortin-3 and melanocortin-5 receptors contribute to energy balance and exocrine function.
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
Regulatory treatment varies between countries. Several national medicines agencies have classified the peptide as unapproved, and customs authorities in some jurisdictions seize shipments on that basis. A few jurisdictions channel supply through prescription-only frameworks that do not list the substance by name. Because the material circulates mainly through online vendors, composition and purity are rarely verified before sale. Surveys of unapproved peptide products have reported labels that did not match measured content in a substantial fraction of samples.
| Property | Value | Notes |
|---|---|---|
| Compound class | Synthetic cyclic heptapeptide | Alpha-MSH analogue containing a D-phenylalanine residue |
| Molecular formula | C50H69N15O9 | Average molecular mass approximately 1024.2 g/mol |
| Appearance | White to off-white lyophilised powder | Normally supplied as a freeze-dried solid in a sealed vial |
| Solubility | Freely soluble in water and polar solvents | Dissolves readily in aqueous buffers and in alcohol-water mixtures |
| Receptor targets | MC1R, MC3R, MC4R, MC5R | Acts as a non-selective melanocortin receptor agonist |
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.
Pharmacologically, melanotan-2 behaves as a non-selective agonist across the melanocortin receptor family. Binding at MC1R on dermal melanocytes promotes eumelanin synthesis, which underlies the tanning response described in early human work. Activity at the centrally expressed MC4R receptor is associated with reported effects on appetite and erectile function. Because the peptide does not discriminate strongly among receptor subtypes, attributing any single observed effect to one receptor pathway is generally not possible without selective antagonists or receptor knockout models.
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.
In ultraviolet astronomy, measurements are used to discern the chemical composition of the interstellar medium, and the temperature and composition of stars. Because the ozone layer blocks many UV frequencies from reaching telescopes on the surface of the Earth, most UV observations are made from space.
In 1897, John Jacob Abel (1857–1938) of Johns Hopkins University, the first chairman of the first US department of pharmacology, found a compound called epinephrine with the molecular formula of C17H15NO4. Abel claimed his principle from adrenal gland extract was active. In 1900, Jōkichi Takamine (1854–1922), a Japanese chemist, worked with his assistant, Keizo Uenaka (1876–1960), to purify a 2000 times more active principle than epinephrine from the adrenal gland, named adrenaline with the molecular formula C10H15NO3. Additionally, in 1900 Thomas Aldrich of Parke-Davis Scientific Laboratory also purified adrenaline independently. Takamine and Parke-Davis later in 1901 both got the patent for adrenaline. The fight for terminology between adrenaline and epinephrine was not ended until the first adrenaline structural discovery by Hermann Pauly (1870–1950) in 1903 and the first adrenaline synthesis by Friedrich Stolz (1860–1936), a German chemist in 1904. They both believed that Takamine's compound was the active principle while Abel's compound was the inactive one. Stolz synthesized adrenaline from its ketone form (adrenalone).
== Terminology == Although bacteria are conventionally divided into two main groups—Gram-positive and Gram-negative, based upon their Gram-stain retention property—this classification system is ambiguous as it can refer to three distinct aspects (staining result, cell-envelope organization, taxonomic group), which do not necessarily coalesce for some bacterial species. In most situations such as in this article, Gram-staining reflects the marked differences in the ultrastructure and chemical composition of the two main kinds of bacteria. The usual "Gram-positive" type does not have an outer lipid membrane, while the typical "Gram-negative" bacterium does. The terms "diderm" and "monoderm", coined to refer to this distinction only, is a more reliable and fundamental characteristic of the bacterial cells.
==== Cambodia ==== On August 30, 2021, 7-Eleven and Thailand's Charoen Pokphand opened the first 7-Eleven store in Phnom Penh's Chroy Changvar district. The company hinted at plans to open at least six more stores in Phnom Penh in 2021. According to plans, products from local small- and medium-sized enterprises (SME) sold in 7-Eleven in Cambodia will comprise at least 50 percent of the stock.
Sources: en.wikipedia.org
=== Support of Alan L. Hart === Lawrence played a supportive role in the early career of physician and radiologist Alan L. Hart. Following Hart’s transition in 1917, she provided professional advocacy and a written recommendation that helped him secure a medical appointment at the Albuquerque Sanatorium.
=== All-terrain droplet actuation (ATDA) === All-terrain microfluidics is a method used to transport liquid droplets over non-traditional surface types. Unlike traditional microfluidics platform, which are generally restricted to planar and horizontal surfaces, ATDA enables droplet manipulation over curved, non-horizontal, and inverted surfaces. This is made possible by incorporating flexible thin sheets of copper and polyimide into the surface via a rapid prototyping method. This device works very well with many liquids, including aqueous buffers, solutions of proteins and DNA, and undiluted bovine serum. ATDA is compatible with silicone oil or pluronic additives, such as F-68, which reduce non-specific absorption and biofouling when dealing with biological fluids such as proteins, biological serums, and DNA. A drawback of a setup like this is accelerated droplet evaporation. ATDA is a form of open digital microfluidics, and as such the device needs to be encapsulated in a humidified environment in order to minimize droplet evaporation.
=== Early roots === Long before modern companies existed, economies still needed people and firms that could bridge distance, timing, and risk between producers and buyers. Economic historians describe the rise of merchants and other intermediaries as a recurring feature of market development, including in ancient trade and later market commerce.
Entertainment Weekly critic Owen Gleiberman wrote that DiCaprio did not look old enough to play the part, but praised him as "a fluid and instinctive actor, with the face of a mischievous angel". The Guardian's Alex von Tunzelmann was similarly impressed with the actor's performance but found his talent wasted in the film. DiCaprio won a Golden Raspberry Award for Worst Screen Couple for the dual roles in 1999. Following the release of Titanic, and The Man in the Iron Mask, DeCaprio chose to reduce his workload "to learn to hear [his] own voice in choosing the roles" that he wanted to pursue. He said in 2000: "I have no connection with me during that whole Titanic phenomenon and what my face became around the world [...] I'll never reach that state of popularity again, and I don't expect to [...] It's not something I'm going to try to achieve either." DiCaprio was next cast to star in an earlier version of American Psycho (2000) for a reported salary of $20 million; after disagreements with Oliver Stone on the film's direction, DiCaprio left the project, taking the lead role in The Beach instead. Adapted from Alex Garland's 1996 novel, the film saw him play a backpacking American tourist who ends up in a secret island commune in the Gulf of Thailand. Budgeted at $50 million, the film earned almost three times that at the box office, but was negatively reviewed by critics, and earned him a nomination for the Golden Raspberry Award for Worst Actor. Todd McCarthy of Variety thought DiCaprio gave a compelling performance but his character lacked defining qualities.
Cromoglicic acid (INN)—also referred to as cromolyn (USAN), cromoglycate (former BAN), or cromoglicate—is traditionally described as a mast cell stabilizer, and is commonly marketed as the sodium salt sodium cromoglicate or cromolyn sodium. This drug prevents the release of inflammatory chemicals such as histamine from mast cells. It is considered a breakthrough drug in management of asthma, as the patients can be freed from steroids in many cases; however, it is mainly effective as a prophylaxis for allergic and exercise-induced asthma, not as a treatment for acute asthma attacks. Cromoglicic acid has been the non-corticosteroid treatment of choice in the treatment of asthma, for which it has largely been replaced by leukotriene receptor antagonists because of their safety and convenience. Cromoglicic acid requires administration four times daily, and does not provide additive benefit in combination with inhaled corticosteroids.
Sources: en.wikipedia.org
Although it remains uncertain as to who was involved in this incident, there has been immediate assertions that North Korea is connected, as it threatened to attack South Korea's government institutions, major national banks and traditional newspapers numerous times – in reaction to the sanctions it received from nuclear testing and to the continuation of Foal Eagle, South Korea's annual joint military exercise with the United States. North Korea's cyber warfare capabilities raise the alarm for South Korea, as North Korea is increasing its manpower through military academies specializing in hacking. Current figures state that South Korea only has 400 units of specialized personnel, while North Korea has more than 3,000 highly trained hackers; this portrays a huge gap in cyber warfare capabilities and sends a message to South Korea that it has to step up and strengthen its Cyber Warfare Command forces. Therefore, in order to be prepared from future attacks, South Korea and the United States will discuss further about deterrence plans at the Security Consultative Meeting (SCM). At SCM, they plan on developing strategies that focuses on accelerating the deployment of ballistic missiles as well as fostering its defense shield program, known as the Korean Air and Missile Defense.
=== Alcoholic beverages === Alcoholic beverages are defined as beverages that contain ethanol (C2H5OH). This ethanol is almost always produced by fermentation – the metabolism of carbohydrates by certain species of yeasts under anaerobic or low-oxygen conditions. Beverages such as mead, wine, beer, or distilled spirits all use yeast at some stage of their production. A distilled beverage is a beverage containing ethanol that has been purified by distillation. Carbohydrate-containing plant material is fermented by yeast, producing a dilute solution of ethanol in the process. Spirits such as whiskey and rum are prepared by distilling these dilute solutions of ethanol. Components other than ethanol are collected in the condensate, including water, esters, and other alcohols, which (in addition to that provided by the oak in which it may be aged) account for the flavour of the beverage.
== Importance == Penicillium expansum produces the mycotoxin patulin, a neurotoxin that can enter the food supply via apples and apple products such as juice and cider. Considering the size of the apple product industry and the large number of people that may come into contact with infected fruits, control of P. expansum is vitally important.
As menin is located predominantly in the nucleus, these mutations can impact the stability of the cell and may further affect functional activity or expression levels of the protein. Studies have also shown that single amino acid changes in genes involved in oncogenic disorders may result in proteolytic degradation leading to loss of function and reduced stability of the mutant protein; a common mechanism for inactivating tumor suppressor gene products. MEN1 gene mutations and deletions also play a role in the development of hereditary and a subgroup of sporadic pituitary adenomas and were detected in approximately 5% of sporadic pituitary adenomas. Consequently, alterations of the gene represent a candidate pathogenetic mechanism of pituitary tumorigenesis especially when considered in terms of interactions with other proteins, growth factors, oncogenes play a rule in tumorigenesis. Although the exact function of MEN1 is not known, the Knudson "two-hit" hypothesis provides strong evidence that it is a tumor suppressor gene. Familial loss of one copy of MEN1 is seen in association with MEN-1 syndrome. Tumor suppressor carcinogenesis follows Knudson's "two-hit" model. The first hit is a heterozygous MEN1 germline mutation either developed in an early embryonic stage and consequently present in all cells at birth for the sporadic cases, or inherited from one parent in a familial case. The second hit is a MEN1 somatic mutation, oftentimes a large deletion occurring in the predisposed endocrine cell and providing cells with the survival advantaged needed for tumor development.
Sources: en.wikipedia.org
No. It is a laboratory-made peptide, while the natural hormone is alpha-melanocyte-stimulating hormone, a longer peptide produced by the pituitary gland and by skin cells. Melanotan-2 mimics only a short active region of that hormone and contains non-natural residues such as D-phenylalanine.
No approved regulatory indication exists in major markets. An approval exists for a different peptide, afamelanotide, which is used for a rare photosensitivity disorder called erythropoietic protoporphyria. Melanotan-2 itself remains a research compound with no cleared clinical role.
Melanocortin-1 receptors on melanocytes are the receptor most closely linked to pigment production. The peptide is not selective, however, and also activates melanocortin-3, melanocortin-4, and melanocortin-5 receptors. That lack of selectivity is the usual explanation offered for both its range of observed effects and its off-target effects.
No. No major regulatory agency has granted a marketing authorisation for melanotan II as a medicine. Products sold under this name are generally presented as laboratory reagents and are not subject to the batch-release testing applied to approved drugs.