MC1R raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2026-07-09. Anything still debated is marked as such rather than presented as settled.
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.
Lyophilised peptide powder is comparatively stable when kept dry, cold and protected from light. Once dissolved, the molecule is exposed to hydrolysis, oxidation and microbial growth, and degradation accelerates at higher temperatures and in alkaline solution. Repeated freeze-thaw cycles concentrate solutes and promote aggregation. Handling guidance for research peptides commonly clusters around freezer temperatures for powder and short refrigerated use for reconstituted solutions, with pH control and sterile technique applied throughout.
Verification of a purchased sample requires documentation linking a batch to a certificate of analysis, and that document should be read for the methods used rather than the headline purity figure. A single chromatographic percentage does not establish identity. Independent laboratories can perform identity and content assays, but no such test establishes that a product is suitable for human use. Claims about efficacy rest largely on small, early studies rather than on replicated controlled trials, and that gap remains open.
| 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 |
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.
Solid peptide kept dry at minus twenty degrees Celsius, shielded from light and moisture, is generally considered stable for extended periods. Solutions are divided into single-use aliquots and held at minus twenty or minus eighty degrees Celsius, because repeated freeze-thaw cycles promote aggregation and loss of material to container surfaces. Hydrolysis of the backbone and oxidation of tryptophan are the principal degradation routes in aqueous solution, and both accelerate at ambient temperature. Hygroscopic uptake after a vial is opened can also shift the actual mass weighed, which affects any concentration calculated from it.
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.
=== Intravenous administration === Serum vancomycin levels may be monitored in an effort to reduce side effects, but the value of such monitoring has been questioned. Peak and trough levels are usually monitored, and for research purposes the area under the concentration curve is also sometimes used. Toxicity is best monitored by looking at trough values. Immunoassays are commonly used to measure vancomycin levels. Common adverse drug reactions (≥1% of patients) associated with intravenous vancomycin include:
== Adverse effects == Fluvoxamine's side-effect profile is very similar to other SSRIs. Gastrointestinal side effects are characteristic of those receiving treatment with fluvoxamine. However, compared to escitalopram and sertraline, fluvoxamine's gastrointestinal profile may be less intense, often being limited to nausea. Mosapride has demonstrated efficacy in treating fluvoxamine-induced nausea. It is also advised practice to divide total daily doses of fluvoxamine greater than 100 mg, with the higher fraction being taken in the evening (e.g., 50 mg at the beginning of the waking day and 200 mg at bedtime). In any case, high starting daily doses of fluvoxamine rather than the recommended gradual titration (starting at 50 mg and gradually titrating, up to 300 mg if necessary) may increase the likelihood of nausea. In comparison to other SSRIs, fluvoxamine has the second highest rate of causing discontinuation syndrome, as a result of the low half-life of fluvoxamine.
In September 2022, the WHO updated their guidelines to recommend use of remdesivir for both non-hospitalized and hospitalized patients. This was based on final results from the SOLIDARITY trial that showed a reduction in mortality or progression to mechanical ventilation for non-ventilated patients.
== History == French pharmaceutical company Hoechst Marion Roussel (later Sanofi-Aventis) began phase II/III clinical trials of telithromycin (HMR-3647) in 1998. Telithromycin was approved by the European Commission in July 2001 and subsequently went on sale in October 2001. In the US, telithromycin received U.S. Food and Drug Administration (FDA) approval on April 1, 2004.
Sources: en.wikipedia.org
In 2010, Tim Hortons opened two kiosks at Consol Energy Center (now known as PPG Paints Arena) in Pittsburgh, partly as a test to eventual expansion into Pittsburgh (their closest locations at that point were in the Wheeling, West Virginia/Steubenville, Ohio, area) as well as Pittsburgh Penguins star Sidney Crosby having a longtime sponsorship with the chain as well. In addition, Horton played for the Maple Leafs American Hockey League affiliate, the Pittsburgh Hornets, earlier in his career as well as the Penguins for one season in 1971 to 1972. Aramark, which operated the kiosks, closed them in 2012, however Tim Hortons proceeded to open full-service locations in Pittsburgh and surrounding areas in July 2012. At the time of the entry into Pittsburgh, of the four NHL cities Horton played in (Buffalo, New York City, Toronto, and Pittsburgh), Pittsburgh was the only one without a Tim Hortons location, and was also where Horton met his future wife, Lori. In 2011, Tim Hortons aggressively expanded into the Grand Rapids, Michigan, region. In 2012, Tim Hortons began advertising in the Youngstown, Ohio, area in anticipation of an eventual expansion into the Mahoning Valley. The closest location at the time was in Calcutta, Ohio, about 50 miles south of Youngstown. The chain entered the area in July 2012 with the opening of a location in Hermitage, Pennsylvania.
Trump's second term foreign policy has been described as a mixture of both imperialist and expansionist policies. He engaged in a realist and isolationist "America First" foreign policy agenda. His administration favored hard power to achieve foreign policy goals, and dismantled or withdrew support from domestic and international organizations dedicated to advancing American soft power. The moves were described as ceding American global influence and creating a void filled by Russia and China. His relations with allies were transactional and ranged from indifference to hostility, and he threatened them with economic tariffs or annexation. He was described as taking the side of Russia in the Russian invasion of Ukraine, and overseeing a rupture of the post-1945 rules-based liberal international order and abandonment of multilateralism. Michael Klare wrote that containing the influence of China and preventing the rise of any rival power is the central foreign policy objective of the administration. Trump has attempted to deepen the U.S.-India partnership. Trump's administration saw large drops in global public opinion of the U.S. Countries like Canada, Germany, the U.K., Denmark, and Finland warned their citizens about traveling to the U.S.
In 2001, 35 patients filed a class-action suit alleging they had had withdrawal symptoms, and in 2002, a Los Angeles court issued an injunction preventing GSK from advertising that the drug was not habit forming. The court withdrew the injunction after the FDA objected that the court had no jurisdiction over drug marketing that the FDA had approved. In 2003, a World Health Organization committee reported that Paxil was among the top 30 drugs, and top three antidepressants, for which dependence had been reported.
=== Techniques === There are four major methods used to quantify the metabolome of single cells; they are: fluorescence–based detection, fluorescence biosensors, FRET biosensors, and mass spectroscopy. The first three methods listed use fluorescence microscopy to detect molecules in a cell. Usually these assays use small fluorescent tags attached to molecules of interest, however this has been shown be too invasive for single cell metabolomics, and alters the activity of the metabolites. The current solution to this problem is to use fluorescent proteins which will act as metabolite detectors, fluorescing whenever they bind to a metabolite of interest. Mass spectroscopy is becoming the most frequently used method for single cell metabolomics. Its advantages are that there is no need to develop fluorescent proteins for all molecules of interest, and is capable of detecting metabolites in the femtomole range. Similar to the methods discussed in proteomics, there has also been success in combining mass spectroscopy with separation techniques such as capillary electrophoresis to quantify metabolites. This method is also capable of detecting metabolites present in femtomole concentrations. Another method utilizing capillary microsampling combined with mass spectrometry with ion mobility separation has been demonstrated to enhance the molecular coverage and ion separation for single cell metabolomics. Furthermore, direct infusion mass spectrometry, so call-ed live-single cell mass spectrometry, has also been successfully performed on human cells.
== Further reading == Rees, Jonathan. Refrigeration Nation: A History of Ice, Appliances, and Enterprise in America (Johns Hopkins University Press; 2013) 256 pages Refrigerators and food preservation in foreign countries. United States Bureau of Statistics, Department of State. 1890.
Sources: en.wikipedia.org
== Micro-encapsulation == Spray drying often is used as an encapsulation technique by the food and other industries. A substance to be encapsulated (the load) and an amphipathic carrier (usually some sort of modified starch) are homogenized as a suspension in water (the slurry). The slurry is then fed into a spray drier, usually a tower heated to temperatures above the boiling point of water. As the slurry enters the tower, it is atomized. Partly because of the high surface tension of water and partly because of the hydrophobic/hydrophilic interactions between the amphipathic carrier, the water, and the load, the atomized slurry forms micelles. The small size of the drops (averaging 100 micrometers in diameter) results in a relatively large surface area which dries quickly. As the water dries, the carrier forms a hardened shell around the load. Load loss is usually a function of molecular weight. That is, lighter molecules tend to boil off in larger quantities at the processing temperatures. Loss is minimized industrially by spraying into taller towers. A larger volume of air has a lower average humidity as the process proceeds. By the osmosis principle, water will be encouraged by its difference in fugacities in the vapor and liquid phases to leave the micelles and enter the air. Therefore, the same percentage of water can be dried out of the particles at lower temperatures if larger towers are used. Alternatively, the slurry can be sprayed into a partial vacuum.
==== Aggravation of certain skin conditions ==== Ultraviolet radiation can aggravate several skin conditions and diseases, including systemic lupus erythematosus, Sjögren's syndrome, Sinear Usher syndrome, rosacea, dermatomyositis, Darier's disease, Kindler–Weary syndrome and Porokeratosis.
=== Diseases === Verticillium wilt is a major constraint in peppermint cultivation. 'Todd's Mitcham', 'Refined Murray', 'Roberts Mitcham' (see above), and a few other cultivars have some degree of resistance.
As of October 2024, Novo was the second most valuable drug company in the world by market capitalization, second only to its competitor Eli Lilly and Company. By July 2025, Novo had fallen to become the fifth most valuable drug company amid rising competition from generic weight loss substitutes. The company named Maziar Mike Doustdar as the new CEO, effective August 7, 2025. In March 2025, the company announced new plans for a direct-to-consumer offering of its Wegovy weight loss drug. The company established a new pharmacy, called NovoCare, which would charge customers $499 per month for access to the drug, less than half the cost of the drug through other pharmaceutical distribution networks. In September 2025, Novo announced that it would reduce its global workforce by 9,000 people, approximately 9% of its total workforce. In October 2025, Novo acquired Akero Therapeutics for $5.2 billion. Akero Therapeutics is a clinical stage company focusing on the treatment of metabolic dysfunction-associated steatohepatitis (MASH).
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.
Mass spectrometry combined with liquid chromatography provides both molecular weight confirmation and a measure of related impurities. Tandem mass spectrometry adds sequence information. A purity percentage reported without a mass measurement does not confirm what the material is.