afamelanotide comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2025-09-12. Where a claim depends on a specific study, the study is described rather than over-claimed.
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 appears on the World Anti-Doping Agency prohibited list within the peptide hormone class, and several national regulators treat it as an unapproved prescription substance. Some countries restrict importation or sale for personal use. Because the compound is widely traded as a research chemical, the practical legal picture differs between jurisdictions and shifts over time. Human safety data covering long periods are limited, and whether repeated pigmentation changes carry any lasting risk to melanocytes remains an open question.
Freeze-dried melanotan-2 is normally kept as a desiccated powder at minus twenty degrees Celsius or lower, shielded from light and moisture. Peptides of this size degrade through hydrolysis, oxidation and deamidation, and each pathway accelerates as temperature and water activity rise. Repeated freeze-thaw cycles promote aggregation and loss of material, so aliquoting a stock solution before freezing is standard laboratory practice. Once dissolved, the solution is markedly less stable than the powder. In laboratory work, solutions are generally refrigerated and used within days rather than kept for months.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, which separates the target peptide from truncated or oxidised impurities. Mass spectrometry, most often coupled to liquid chromatography, confirms molecular mass and detects substitutions that chromatography alone may miss. Amino acid analysis and peptide mapping supply additional structural evidence, while nuclear magnetic resonance is reserved for full structural confirmation. Laboratories that examine samples sold online report wide variation in actual content, with some vials containing little or none of the labelled material.
| 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 |
Melanotan II binds several melanocortin receptor subtypes rather than a single target. MC1R on melanocytes drives melanin synthesis, while MC3R and MC4R participate in energy balance, appetite, and sexual response pathways. This lack of selectivity explains why reported effects extend beyond skin darkening. Substitutions at positions four and seven, including norleucine and D-phenylalanine, increase potency and resistance to peptidases. Understanding which receptor mediates which effect remains an active area of investigation.
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.
Regulatory treatment varies by country. In the United States, melanotan-2 is not approved for any indication, and products marketed for human use fall outside the approved drug framework. Some other jurisdictions have placed it under prescription controls or listed it as a prohibited or restricted substance. Online listings frequently describe the material as a research chemical, a category that does not carry the same manufacturing and labelling requirements as approved medicines.
Solid peptide material is generally stable when kept cold and dry. Common practice is storage at -20 degrees Celsius or lower, with desiccant and protection from light. Repeated freeze-thaw cycles and exposure to moisture are associated with degradation, aggregation, or loss of material. Once dissolved, stability depends on solvent, concentration, and temperature, and solutions are usually treated as short-lived unless stability data support longer periods. Handling notes typically emphasise minimising time at ambient temperature.
Cigarettes are taxed both to reduce use and to raise revenue. Higher prices for cigarettes discourage smoking. Every 10% increase in the price of cigarettes reduces youth smoking by about 7% and overall cigarette consumption by about 4%. The World Health Organization (WHO) recommends that globally cigarettes be taxed at a rate of at least 75% of their sale price as a way of deterring cancer, cardiovascular diseases and other negative health outcomes. Cigarette sales are a significant source of tax revenue in many countries. This fact has historically been an impediment for health groups seeking to discourage cigarette smoking, since governments seek to maximize tax revenues. Furthermore, some countries have made cigarettes a state monopoly, which has the same effect on the attitude of government officials outside the health field.
== Biology and medicine == Gamma-glutamyltransferase, an enzyme that catalyzes the reaction between a peptide and an amino acid Glutathione hydrolase, an enzyme that hydrolyzes glutathione A codon for the amino acid Glycine Germline gene therapy, to treat genetic diseases
== Syntheses == Salts of many cyclopropenyl cations have been characterized. Their stability varies according to the steric and inductive effects of the substituents. Salts of triphenylcyclopropenium were first reported by Ronald Breslow in 1957. The salt was prepared in two steps starting with the reaction of phenyldiazoacetonitrile with diphenylacetylene to yield 1,2,3-triphenyl-3-cyclopropene nitrile. Treatment of this with boron trifluoride yielded [C3Ph3]BF4.
Lastly, the sixth variant (K5R_I10H_F12W) was developed by combining the amino acid substitutions of the first and second variants. Moreover, researchers from the Clemens-Schöpf Institute of Organic Chemistry and Biochemistry and Helmholtz-Institute for Pharmaceutical Research Saarland, developed potent synthetic human matriptase-1 inhibitors based on a different SFTI-1 variant, SDMI-1. SFTI-1 derived matriptase inhibitor-1 (SDMI-1) was previously developed by replacing residue 10 of SFTI-1 (isoleucine, I) with arginine (R) and residue 12 (phenylalanine, F) with histidine (H). Further modifications of SDMI-1 resulted in synthetic matriptase-1 inhibitors with improved inhibitory activity, matriptase binding, and inhibition potency. The SDMI-1 variant that resulted in enhanced inhibitory activity was developed by replacing residue 1 of SDMI-1 (glycine, G) with lysine (K) and by keeping it as a monocyclic structure. The SDMI-1 variant that resulted in improved matriptase binding was created by using the same amino acid substitutions of the previously mentioned SDMI-1 variant and by attaching a bulky fluorescein moiety to the side chain of lysine. Lastly, the SDMI-1 variant that had enhanced inhibition potency was developed by applying the same amino acid substitutions of the previous variants, cleaving the proline-aspartic acid sequence found at the C-terminus (PD-OH), and by making it a bicyclic compound via tail-to-side-chain cyclization.
=== Identification of structural patterns === This method builds a library of known protein–protein interfaces from the PDB, where the interfaces are defined as pairs of polypeptide fragments that are below a threshold slightly larger than the Van der Waals radius of the atoms involved. The sequences in the library are then clustered based on structural alignment and redundant sequences are eliminated. The residues that have a high (generally >50%) level of frequency for a given position are considered hotspots. This library is then used to identify potential interactions between pairs of targets, providing that they have a known structure (i.e. present in the PDB).
Sources: en.wikipedia.org
=== Closure === McDonald's announced on May 23, 2025, that the CosMc's concept would cease operations at all five remaining locations (four in Texas and one in Illinois). The company indicated that starting one month later, the rewards program, mobile ordering and app would no longer function, and rolling closures of the physical locations would begin. Citing learnings from proofs of concepts at the pilot locations, they expect to test some of the most successful beverage concepts at several mainline McDonald's restaurants. CEO Chris Kempczinski stated that the concept was “quarantining the complexity in a stand-alone concept.” He also stated that brand contradiction, absence of experience, and a steep loss in revenue and sales were the reasons why the concept was shutting down.
=== Appearance and odour === Mephedrone is a white substance. It is sold most commonly as crystals or a powder, but also in the form of capsules or pills. It can have a distinctive odour, reported to range the smell of vanilla and bleach, stale urine, or electric circuit boards. Synthesis byproducts or other contaminants are likely responsible for this, as the molecule itself is not an odorant.
Ana María Muñoz Jauregui (born 1969, Lima) is a Peruvian pharmacist, biochemist and nutritionist. She has served as Rector and, since 2023, as the Vice Rector of research at San Ignacio de Loyola University (USIL). Muñoz has authored numerous publications and received national and international awards, such as silver, gold medals and semi-grand prize wins at the International KIWIE Award. Muñoz, was born in Lima, Peru. In 1996, she attended the National University of San Marcos (UNMSM), where she earned her pharmaceutical degree. While studying, she developed an interest in the field of nutrition. She earned a master's degree in biochemistry and nutrition, and earned a PhD in Pharmacy and Biochemistry from the National University of San Marcos (UNMSM) in 2006.
14C + O2 → 14CO + O 14CO + OH → 14CO2 + H Carbon dioxide produced in this way diffuses in the atmosphere, is dissolved in the ocean, and is taken up by plants via photosynthesis. Animals eat the plants, and ultimately the radiocarbon is distributed throughout the biosphere. The ratio of 14C to 12C is approximately 1.25 parts of 14C to 1012 parts of 12C. In addition, about 1% of the carbon atoms are of the stable isotope 13C. The equation for the radioactive decay of 14C is:
Sources: en.wikipedia.org
The television spot which premiered during the Super Bowl LIII features archival documentary film footage from "66 Scenes from America" by Jørgen Leth of the pop artist Andy Warhol (1928–1987) unwrapping and eating a Whopper. The footage was approved for use by the fast food giant courtesy of the Andy Warhol Foundation. Meanwhile, prior to the game, the mass market hamburger chain made available to viewers who ordered it in advance via DoorDash an "Andy Warhol Mystery Box" which contains among other items a plastic bottle of ketchup and a platinum wig so one can "Eat Like Andy". On March 8, 2021, Burger King was criticized for their International Women's Day marketing campaign, after a tweet from Burger King UK stated, "Women belong in the kitchen". The tweets were labeled as sexist by thousands of Twitter users and dozens of news publications. Burger King UK followed up, stating "We're on a mission to change the gender ratio in the restaurant industry." However, critics said the damage had already been done. The initial tweet received high amounts of recognition and viewer interaction, while the replies received a fraction of the coverage, meaning only a few people are aware of the clarifications made by Burger King. Burger King deleted the tweet 12 hours later and posted an apology stating, "We got our initial tweet wrong and we're sorry." In late 2022, Burger King released the "Have it Your Way" commercials, going viral on social media such as TikTok after the 2022–23 NFL playoffs because of its large amount of repetition and catchiness.
Crude oil varies greatly in appearance depending on its composition. It is usually black or dark brown (although it may be yellowish, reddish, or even greenish). In the reservoir it is usually found in association with natural gas (which being lighter forms a "gas cap" over the petroleum) and saline water (which being heavier than most forms of crude oil, generally sinks beneath it). Crude oil may also be found in a semi-solid form mixed with sand and water, as in the Athabasca oil sands in Canada, where it is usually referred to as crude bitumen. In Canada, bitumen is considered a sticky, black, tar-like form of crude oil which is so thick and heavy that it must be heated or diluted before it will flow. Venezuela also has large amounts of oil in the Orinoco oil sands, although the hydrocarbons trapped in them are less viscous than in Canada and are usually called extra heavy oil. Oil sands resources are called unconventional oil to distinguish them from oil which can be extracted using traditional oil well methods. Between them, Canada and Venezuela contain an estimated 3.6 trillion barrels (570×10^9 m3) of bitumen and extra heavy oil, about twice the volume of the world's reserves of conventional oil.
The MECP2 locus is X-linked and the disease-causing alleles are dominant. Due to its prevalence in females, it has been linked to male lethality, or to a predominant transmission with the paternal X chromosome; nevertheless, in rare cases some males can also be affected by Rett syndrome. Males with gene duplications of MECP-2 at the Xq28 locus are also at risk for recurrent infections & meningitis in infancy. Mutations in the MECP2 gene have also been identified in people with several other disorders affecting the central nervous system. For example, MECP2 mutations are associated with some cases of moderate to severe X-linked intellectual disability. Mutations in the gene have also been found in males with severe brain dysfunction (neonatal encephalopathy) who live only into early childhood. In addition, several people with features of both Rett syndrome and Angelman syndrome (a condition characterized by intellectual disability, problems with movement, and inappropriate laughter and excitability) have mutations in the MECP2 gene. Lastly, MECP2 mutations or changes in the gene's activity have been reported in some cases of autism (a developmental disorder that affects communication and social interaction). More recent studies reported genetic polymorphisms in the MeCP2 gene in patients with systemic lupus erythematosus (SLE). SLE is a systemic autoimmune disease that can affect multiple organs. MeCP2 polymorphisms have been reported so far in European-derived and Asian lupus patients.
Valve, the developers of Source and Half-Life 2, contacted Newman to suggest a commercial, standalone release of the mod through their digital distribution service Steam, which Newman initially rejected. Valve and Facepunch later struck a publishing agreement wherein Valve would release Garry's Mod onto Steam at a price of US$10, while the two companies would equally split profits. The last free version of Garry's Mod remained available for download, rechristened as the demo to the retail game. The standalone game was released on 29 November 2006. Despite the game no longer being a mod, Valve and Facepunch stuck with the "Garry's Mod" name, which Newman later cited as a mistake, stating that he should have called it "Sandbox" instead. Because Garry's Mod still required a separate Source-based game to function properly, a bundle including Garry's Mod and Valve's Counter-Strike: Source was released alongside. A port of the Windows version for Mac OS X was released on 23 September 2010. Support for Kinect, a full-body motion tracking peripheral, was added to the Windows version in December 2012. When Garry's Mod was moved over to Valve's SteamPipe content delivery system, completed on 5 June 2013, an experimental Linux client was also introduced. In 2025, an update to the game added popularly-used assets from Counter-Strike: Source and episodic content from Half-Life 2, addressing a majority of missing content issues found in community maps and caused by not having the aforementioned games installed.
Bacteria also use contact-dependent signaling, notably to limit their growth. Signaling molecules used by multicellular organisms are often called pheromones. They can have such purposes as alerting against danger, indicating food supply, or assisting in reproduction.
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.
The lyophilised solid is best kept cold, dry and dark, typically at minus twenty degrees Celsius. Moisture and repeated warming cycles are the main causes of degradation. Solutions prepared from the powder are less stable and are normally used quickly.