MC1R raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-01-02. Anything still debated is marked as such rather than presented as settled.
Routine characterisation relies on reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, using a C18 column and a water-acetonitrile gradient containing trifluoroacetic acid. Electrospray ionisation mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidised by-products that co-elute poorly. Sequence and stereochemistry require additional work, such as peptide mapping or amino acid analysis, because a chromatographic purity figure alone does not distinguish a diastereomer from the target peptide. Independent testing of research-grade material frequently shows measured content below the stated label, so a certificate of analysis is best read together with the method that produced it.
Melanotan-2 is handled in the laboratory as a lyophilised powder that dissolves readily in water, dimethyl sulfoxide and dimethylformamide, with limited solubility in ethanol. Stock solutions prepared in an organic solvent often precipitate when diluted into aqueous buffer, so gradual dilution with mixing is standard practice. The peptide carries a tryptophan residue and a histidine residue, both sensitive to oxidation and to alkaline conditions. Working solutions are therefore kept near neutral to slightly acidic pH, protected from light, and consumed within the same working session whenever that is practical.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised material may be hygroscopic |
| Solubility class | Soluble in water, DMSO and DMF | Dilution into aqueous buffer can cause precipitation |
| Storage of solid | Minus 20 degrees C, desiccated, dark | Aliquot to limit repeated opening of the vial |
| Storage of solution | Minus 20 to minus 80 degrees C, aliquoted | Avoid repeated freeze-thaw cycles |
| Identity method | Reversed-phase HPLC with mass spectrometry | Retention time and mass are checked together |
The material is commonly handled as a lyophilized powder in sealed vials. The solid dissolves readily in water and in polar organic solvents, producing a clear solution after reconstitution. Light, heat and repeated freeze-thaw cycles are the concerns most often raised in handling guidance, because peptide bonds and the constrained ring can degrade. Working solutions are generally prepared fresh, and material left in solution is treated as less stable than the dry form. These properties shape how laboratories store and aliquot reference material.
Identity and purity are assessed mainly by reversed-phase high-performance liquid chromatography with ultraviolet detection, often paired with mass spectrometry. Retention time supports identity, while the mass spectrum confirms the molecular weight of the intact peptide. Purity is frequently reported as a percentage of total peak area, a figure that depends on the wavelength, column and gradient used. Impurity profiling may also look for truncated sequences, oxidised forms and residual counterions. Amino acid analysis and peptide mapping provide orthogonal confirmation when required.
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.
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.
Handling guidance for melanotan II follows general practice for small synthetic peptides rather than a product-specific monograph. Lyophilized powder is typically kept at minus twenty degrees Celsius or colder, protected from light and moisture, because warmth and humidity accelerate degradation. Once reconstituted, solutions are usually refrigerated and used within a short window, as hydrolysis and microbial growth both become concerns. Repeated freeze-thaw cycles are generally avoided. These conventions come from laboratory peptide chemistry and not from formal stability studies on this specific compound.
Analytical confirmation of identity relies on mass spectrometry, most often coupled to liquid chromatography. Reversed-phase high-performance liquid chromatography separates the peptide from related impurities and provides a purity estimate based on peak area. Electrospray ionization mass spectrometry then confirms the expected molecular mass, while tandem mass spectrometry can map the fragment sequence. For research-grade material, these two techniques together form the standard minimum. Purity figures reported by vendors are frequently not traceable to an independent laboratory.
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.
The compound emerged from research programs in the 1980s that examined analogues of alpha-melanocyte-stimulating hormone for pigmentation and photoprotection. Investigators modified the native sequence to extend activity duration and potency. A related analogue, afamelanotide, was developed within the same broad line of inquiry and eventually gained approval in certain jurisdictions for a rare light-sensitivity condition. Melanotan-2 itself did not progress through the same regulatory route and has no approved therapeutic indication.
The vascular network within the islets resembles a glomeruli-like structure, consisting of highly fenestrated endothelial cells positioned closely to each endocrine cell. Consequently, the oxygen tension within pancreatic islets is significantly higher than that in the surrounding exocrine tissue.
The yearly Ministerial Council Meeting, with the Ministers of Economy of all member countries and the candidates for enhanced engagement among the countries. The annual OECD Forum, which brings together leaders from business, government, labour, civil society and international organisations. Held every year since June 2000, the OECD Forum takes the form of conferences and discussions, is open to public participation and is held in conjunction with the MCM. Thematic Ministerial Meetings, held among ministers of a given domain (i.e., all Ministers of Labour, all Ministers of Environment, etc.). The bi-annual World Forum on Statistics, Knowledge and Policies, which does not usually take place in the OECD. This series of meetings has the ambition to measure and foster progress in societies. The Forum for Harmful Tax Practices OECD Eurasia Week, which includes several high-level policy dialogue discussions to share best practices and experiences in addressing common development and economic challenges in Eurasia.
Haem-using haem peroxidase and the related animal heme-dependent peroxidases DyP-type peroxidase family Catalase Manganese peroxidase some haloperoxidase Di-haem cytochrome c peroxidase Non-heme Thiol: glutathione peroxidase, peroxiredoxin vanadium bromoperoxidase Alkyl hydroperoxide reductase NADH peroxidase
==== Administration ==== Drugs should only be administered using protective medical devices such as needle lists and closed systems and techniques such as priming of IV tubing by pharmacy personnel inside a ventilated cabinet. Workers should always wear personal protective equipment such as double gloves, goggles, and protective gowns when opening the outer bag and assembling the delivery system to deliver the drug to the patient, and when disposing of all material used in the administration of the drugs. Hospital workers should never remove tubing from an IV bag that contains an antineoplastic drug, and when disconnecting the tubing in the system, they should make sure the tubing has been thoroughly flushed. After removing the IV bag, the workers should place it together with other disposable items directly in the yellow chemotherapy waste container with the lid closed. Protective equipment should be removed and put into a disposable chemotherapy waste container. After this has been done, one should double bag the chemotherapy waste before or after removing one's inner gloves. Moreover, one must always wash one's hands with soap and water before leaving the drug administration site.
Sources: en.wikipedia.org
=== Films and television === Chains (film), a 1949 Italian melodrama film Chains (Blackadder), a 1986 episode of the British sitcom Blackadder II Chain (advertisement), a 1994 television advertisement for Guinness Chains of Love (TV series), a 2001 American dating game show adapted from a Dutch television series Chain (film), a 2004 film written and directed by Jem Cohen Chains, a 2009 short film starring TNA wrestler Kurt Angle
== Sources == AH Brogan, Committed to Saving Lives: a History of the Commonwealth Serum Laboratories (Melbourne: Hyland House, 1990). Dando McCredie, The Fight Against Disease and CSL's Seventy Year Contribution (Richmond: Dando McCredie, c.1986). FG Morgan, 'The Commonwealth Serum Laboratories and their work', Collected Proceedings of the Society of Chemical Industry of Victoria, XXXV (1935), 1015–31. WJ Penfold, 'The Commonwealth Serum Laboratories', Medical Journal of Australia, 1 (14 April 1923), 396–400. Struan K Sutherland, A Venomous Life: the Autobiography of Professor Struan Sutherland (Melbourne: Hyland House, 1998).
The cultivation of plants from which psychotropic substances are obtained is not controlled by the Vienna Convention... Neither the crown (fruit, mescal button) of the Peyote cactus nor the roots of the plant Mimosa hostilis nor Psilocybe mushrooms themselves are included in Schedule I, but only their respective principals, mescaline, DMT, and psilocin. In Peru, ayahuasca is legal and formally protected as part of the country's cultural heritage. When ratifying the 1971 Convention on Psychotropic Substances, Peru entered a reservation to exclude Ayahuasca and San Pedro from international control, citing their traditional ritual use by Amazonian peoples (United Nations Treaty Collection, 1971). This position was reinforced on 24 June 2008, when the Instituto Nacional de Cultura declared the traditional knowledge and ceremonial use of Ayahuasca by Indigenous communities as Patrimonio Cultural de la Nación (Cultural Heritage of the Nation). A fax from the Secretary of the International Narcotics Control Board (INCB) to the Netherlands Ministry of Public Health sent in 2001 goes on to state that "Consequently, preparations (e.g. decoctions) made of these plants, including ayahuasca, are not under international control and, therefore, not subject to any of the articles of the 1971 Convention." Despite the INCB's 2001 affirmation that ayahuasca is not subject to drug control by international convention, in its 2010 Annual Report the Board recommended that governments consider controlling (i.e. criminalizing) ayahuasca at the national level.
Sources: en.wikipedia.org
=== Flavin-dependent ene-reductases === Flavin-dependent ERs perform their reactions using the cofactor flavin mononucleotide (FMN) that is non-covalently bonded to the enzyme and their catalytic mechanism is now well understood. In the natural cycle, the cofactor (FMN) is first reduced by NAD(P)H, then the reduced FMNH2 reduces the substrate by Michael-type hydride transfer to the β-carbon atom. In the end the protonation of the resulting anion occurs from the opposite face of the (C=C) bond through a tyrosine moiety or solvent. The overall reaction is an anti-trans-hydrogenation. This catalytic mechanism can also be regenerated from the natural nicotinamide cofactor with a substrate-coupled regeneration or the use of synthetic reductants and electrochemical or photochemical regeneration. The most predominant family of flavin-dependent ERs is the Old Yellow Enzyme (OYE) family of oxidoreductases (EC 1.6.99.1).The first OYE was discovered in baker's yeast (Saccharomyces cerevisiae) in 1933, and its name derives from the color it assumes when concentrated, which is due to the flavin cofactor. They catalyze the reduction of α,β-unsaturated compounds, with a high specificity for activating groups containing aldehydes, ketones, or nitro groups. Conversely, carboxylic acids and their derivatives such as esters and nitriles, are less activated and are considered as "borderline substrates".
Examples of this style include Joris Ivens' Rain (1928), which records a passing summer shower over Amsterdam; László Moholy-Nagy's Play of Light: Black, White, Grey (1930), in which he films one of his own kinetic sculptures, emphasizing not the sculpture itself but the play of light around it; Oskar Fischinger's abstract animated films; Francis Thompson's N.Y., N.Y. (1957), a city symphony film; and Chris Marker's Sans Soleil (1982). Expository documentaries speak directly to the viewer, often through an authoritative commentary employing voiceover or titles, proposing a strong argument and point of view. These films are rhetorical and try to persuade the viewer. They may use a rich and sonorous male voice. The (voice-of-God) commentary often sounds "objective" and omniscient. Images are often not paramount; they exist to advance the argument. The rhetoric insistently presses upon us to read the images in a certain fashion. Historical documentaries in this mode deliver an unproblematic and "objective" account and interpretation of past events. Examples: TV shows and films like Biography, America's Most Wanted, many science and nature documentaries, Ken Burns' The Civil War (1990), Robert Hughes' The Shock of the New (1980), John Berger's Ways of Seeing (1972), Frank Capra's wartime Why We Fight series, and Pare Lorentz's The Plow That Broke the Plains (1936).
== History == The first Canadian A&W restaurant opened in Winnipeg, Manitoba, in 1956. It spread across Canada with over 200 locations in the next ten years. The Canadian restaurants were part of the American chain until 1972 when they were sold to Unilever. In 1975, facing competition from the growing Canadian operations of McDonald's, the company launched an advertising campaign starring an orange-clad mascot, The Great Root Bear. The bear and the tuba jingle that accompanied him became a long-running campaign (the tune, entitled "Ba-Dum, Ba-Dum", was released as a single by Attic Records, credited to "Major Ursus", a play on Ursa Major or "great bear"). The famous Canadian composer and B.C. Hall of Fame winner Robert Buckley helped compose the song. The mascot was so successful that he was eventually adopted as the mascot by the American A&W chain as well. The famous tuba jingle was played by famed Vancouver jazz, classical and session trombonist Sharman King. In the early 1980s, the drive-in style of restaurant was phased out. It was replaced with a modern, pastel-coloured fast food outlet which included marginally healthier options. While the chain continued to open some standalone restaurants, A&W also aggressively pursued shopping mall locations, and as a result A&Ws are still commonly found in Canadian malls of various sizes.
Sources: en.wikipedia.org
Purity is normally stated as an area percentage from high-performance liquid chromatography, for example ninety-five or ninety-eight percent. That figure describes the proportion of ultraviolet-absorbing material eluting as the main peak. It says nothing about water content, counterions, residual solvents or mass fraction of the peptide itself.
Peptides are commonly isolated as acetate or trifluoroacetate salts, and the counterion contributes to total mass. Two vials with identical peptide content can therefore differ in weight and in measured response. Residual trifluoroacetate is also relevant in cell-based work because it can influence membrane behaviour.
Degradation products are often closely related to the parent molecule, making them hard to resolve with a single method. Counterion variability adds a further source of scatter between laboratories. Because no pharmacopoeial monograph exists for melanotan-2, groups rely on method-specific validation rather than a shared reference standard.
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.