If you have been reading about MC1R and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-04-05. Where a claim depends on a specific study, the study is described rather than over-claimed.
Melanotan-2 is a synthetic cyclic heptapeptide designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous tridecapeptide that regulates pigment production. Two modifications distinguish it from the natural hormone: norleucine replaces methionine at the N-terminus, which limits oxidation, and a D-phenylalanine substitution raises receptor affinity. The ring is closed through an aspartate-lysine lactam bridge, giving the molecule a constrained conformation. The free base has a molecular mass near 1024 daltons, and commercial material is usually supplied as an acetate salt. It appears in the literature as a research peptide rather than an approved therapeutic agent.
Receptor studies place melanotan-2 among non-selective melanocortin agonists, binding MC1R, MC3R, MC4R and MC5R rather than a single subtype. Activation of MC1R on cutaneous melanocytes raises tyrosinase activity and shifts pigment synthesis toward eumelanin, which is darker and more photostable than pheomelanin. Central receptors, particularly MC4R, are associated with appetite suppression and with reported effects on sexual function. Because subtype selectivity is low, the same molecule engages pigment, metabolic and vascular pathways at once, and this breadth is a common explanation offered for the range of adverse events described in user reports.
No regulatory authority has approved melanotan-2 for human use, and several countries classify it as a prescription-only or controlled substance, which restricts lawful supply. Material sold online is generally labelled as a research chemical and is not required to meet pharmaceutical standards of identity or purity. Published human data consist mainly of small uncontrolled studies, case reports and adverse-event notifications, so the evidence base is descriptive rather than confirmatory. Whether repeated melanocyte stimulation alters long-term naevus behaviour remains an open question that no completed trial has resolved.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Free base; salt forms add to total mass |
| Molecular mass | About 1024 daltons | Calculated for the free base |
| Structural class | Cyclic heptapeptide | Contains D-phenylalanine and norleucine |
| Parent hormone | Alpha-melanocyte-stimulating hormone | Endogenous tridecapeptide of 13 residues |
| Receptor profile | Non-selective melanocortin agonist | Interacts with MC1R, MC3R, MC4R and MC5R |
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.
Melanotan II is a synthetic peptide analog modeled on alpha-melanocyte-stimulating hormone, a naturally occurring signaling peptide involved in pigmentation. Its structure is a cyclic heptapeptide containing two non-natural substitutions, norleucine at position four and D-phenylalanine at position seven. These modifications resist enzymatic breakdown and extend the molecule's activity relative to the native hormone. The compound binds melanocortin receptors and is studied mainly as a pharmacological tool rather than a therapeutic product. It has never received approval as a medicine in any major jurisdiction.
The compound was developed in the late 1980s and 1990s by academic researchers investigating photoprotection. The rationale held that stimulating melanin production might reduce ultraviolet damage to skin and lower skin cancer risk. Early work examined receptor binding, pigment response, and short-term tolerability in small studies. That program did not produce an approved drug, and formal development stalled after early-phase trials. Whether induced pigmentation confers meaningful photoprotection remains an open question.
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.
When inadequate methyl is available during early embryonic development, DNA methylation cannot occur, which increases ectopic expression of agouti and results in the presentation of the lethal yellow and viable yellow phenotypes which persist into adulthood. This leads to the development of the yellow obese syndrome, which impairs normal development and increases susceptibility to the development of chronic disease. Ensuring maternal diets are high in methyl equivalents is a key preventive measure for reducing ectopic expression of agouti in offspring. Diet intervention through methyl supplementation reduces imprinting at the agouti locus, as increased methyl consumption causes the IAP element to become completely methylated and ectopic expression of agouti to be reduced. This lowers the proportion of offspring that present with the yellow phenotype and increases the number offspring that resemble agouti wild type mice with grey coats. Two genetically identical mice could look very different phenotypically due to the mothers' diets while the mice were in utero. If the mice has the agouti gene it can be expressed due to the mother eating a typical diet and the offspring would have a yellow coat. If the same mother had eaten a methyl-rich diet supplemented with zinc, vitamin B12, and folic acid then the offspring's agouti gene would likely become methylated, it wouldn't be expressed, and the coat color would be brown instead. In mice, the yellow coat color is also associated with health problems in mice including obesity and diabetes.
The study also highlights economy-specific gap analyses, which illustrate gaps in policy coverage and estimate potential energy savings achieved through the adoption of world’s most comprehensive standards. Compliance Counts: A Practitioners Guidebook on Best Practice Monitoring, Verification, and Enforcement (MV&E) for Appliance Standards &Labeling The Guidebook, published in collaboration with Mark Ellis & Associates, is designed as a step-by-step manual for policymakers and S&L program administrators to design and implement a successful compliance regime. Drawing on the experiences of existing S&L programs worldwide, the Guidebook provides different approaches to implementing and improving all aspects of a compliance framework, including establishment of a legal basis for MV&E activities and enforcement options for non-compliance. According to the guidebook, effective compliance regimes: ensure that consumers receive the products they expect when making purchasing decisions; provide industry participants a fair market in which to operate; and safeguard current and future energy and greenhouse gas emissions savings from S&L programs, among other benefits. Energy Efficiency Labels and Standards: A Guidebook for Appliances, Equipment, And Lighting (also available in Chinese, Spanish and Korean) This guidebook is designed as a manual for government officials and others around the world responsible for developing, implementing, enforcing, monitoring, and maintaining energy efficiency labeling and standard-setting programs. Tools
==== Mechanical exfoliation ==== Geim and Novoselov initially used adhesive tape to pull graphene sheets away from graphite. Achieving single layers typically requires multiple exfoliation steps. After exfoliation, the flakes are deposited on a silicon wafer. Crystallites larger than 1 mm and visible to the naked eye can be obtained. As of 2014, exfoliation produced graphene with the lowest number of defects and highest electron mobility. One specific exfoliation technique involved using a sharp single-crystal diamond wedge to penetrate the graphite source and precisely cleave individual layers. That same year, researchers also developed liquid-phase methods, creating defect-free, unoxidized graphene-containing liquids from graphite using mixers that generate extremely high local shear rates greater than 10×104. A 2014 study published in Nature Materials demonstrated that scalable production of defect-free graphene is possible through shear exfoliation using a high-shear mixer. This technique can produce large quantities of few-layer graphene in solution while preserving structural integrity. As turbulence is not necessary for mechanical exfoliation, resonant acoustic mixing or low-speed ball milling can also be effective in the production of high-yield and water-soluble graphene.
Sources: en.wikipedia.org
Noroxycodone is the major metabolite of the opioid analgesic oxycodone. It is formed from oxycodone in the liver via N-demethylation predominantly by CYP3A4. Noroxycodone binds to and activates the μ-opioid receptor (MOR) similarly to oxycodone, although with one-third of the affinity of oxycodone and 5- to 10-fold lower activational potency. However, although a potent MOR agonist, noroxycodone poorly crosses the blood-brain-barrier into the central nervous system, and for this reason, is only minimally analgesic in comparison.
=== Chemical disinfection with halogens === Chemical disinfection with halogens, chiefly chlorine and iodine, results from oxidation of essential cellular structures and enzymes. The primary factors that determine the rate and proportion of microorganisms killed are the residual or available halogen concentration and the exposure time. Secondary factors are pathogen species, water temperature, pH, and organic contaminants. In field-water disinfection, use of concentrations of 1–16 mg/L for 10–60 min is generally effective. Of note, Cryptosporidium oocysts, likely Cyclospora species, Ascaris eggs are extremely resistant to halogens and field inactivation may not be practical with bleach and iodine.
=== Lifestyle and drug management === Kalra has consistently emphasised the importance of lifestyle interventions in obesity management. He has highlighted the use of traditional and indigenous activities to improve physical function in people living with obesity. He has also worked extensively on nutrition education and research. Kalra has advocated for the recognition of "mega-nutrients" such as fibre and water, which are consumed in significantly larger quantities than macronutrients. He is also a co-author of the national consensus statement on fibre intake in India. Person-centred obesity care is another major focus of his work. His publications emphasise that obesity management requires individualised strategies rather than a uniform approach. Kalra has remained closely engaged with developments in GLP-1 receptor agonists and has published periodic updates as new evidence has emerged.
Sources: en.wikipedia.org
The grave was discovered by a farmer working in a potato-field at Hillside Farm on Bryher in March 1999, when his tractor wheel sank into the ground and to free it he moved a large stone which revealed the cist. He reached into the cavity and found a sword. He contacted the British Museum who advised him to take it to the Isles of Scilly Museum, where it was identified as a La Tène II iron sword. The then Prince Charles visited the farm while on a visit to the islands in May 1999, and a project for the evaluation, recording and reinstatement of the site was undertaken jointly by Cornwall Archaeology Unit, English Heritage and the British Museum.
Scanned letter from Wernher Von Braun to Vice President Johnson Archived May 13, 2005, at the Wayback Machine "America's Space Program: Exploring a New Frontier", a National Park Service Teaching with Historic Places (TwHP) lesson plan Why Did the USSR Lose the Moon Race? from Pravda, 2002-12-03 Space Race Exhibition Archived January 1, 2006, at the Wayback Machine at the Smithsonian National Air and Space Museum TheSpaceRace.com – Mercury, Gemini, and Apollo space programs Timeline of the Space Race to the Moon 1960 – 1969 Archived November 19, 2005, at the Wayback Machine Shadows of the Soviet Space Age, Paul Lucas Chronology:Moon Race at russianspaceweb.com John F. Kennedy Moon Speech at Rice Stadium and Apollo 11 Mission Video on YouTube Sergei Korolev: Father of the Soviet Union’s success in space ESA.int
== Signs and symptoms == The defining sign of kwashiorkor in children is bilateral edema in the feet. Edema may also involve the hands, trunk, and face. Kwashiorkor is characterized by a fatty liver. This fatty liver of the undernutrition phenotype is often accompanied by evidence of inflammation and fibrosis. Whereas a fatty liver of undernutrition is a consistent feature of kwashiorkor, it is only encountered sometimes in children with marasmus. In addition to this characteristic hepatic steatosis, kwashiorkor is marked by a parallel pattern of multi-organ dysfunction. Organs often affected in children with kwashiorkor include the kidneys, pancreas, heart, and nervous system. Other findings that may be encountered on physical exam include a distended abdomen, hair thinning, loss of teeth, skin or hair depigmentation, and dermatitis. Children with kwashiorkor often develop irritability and anorexia. Generally, kwashiorkor is treated by introducing a high-quality source of protein to the diet. Ready-to-use therapeutic food (RUTF) as well as F-100 and F-75 milk powders, which both include skim milk powder, are recommended for the treatment of kwashiorkor. These products are designed for use in low-resource settings. The limited number of kwashiorkor cases that occur in high resource settings, where there is good access to advanced therapeutic tools, are typically treated with partially hydrolyzed or elemental enteral formulas, with parenteral nutrition provided in extreme cases.
Sources: en.wikipedia.org
No regulatory agency has authorised melanotan-2 as a medicine for any indication. It circulates mainly as a research chemical or through unregulated channels. As a result, identity, purity and content are not independently guaranteed.
Melanotan-1, also called afamelanotide, is a linear analogue with greater selectivity for MC1R and has received approval in some jurisdictions for a specific photosensitivity disorder. Melanotan-2 is cyclic, less selective, and reaches central receptors more readily. The two are often confused in online discussion despite different pharmacology and regulatory status.
Alpha-MSH is an endogenous tridecapeptide derived from pro-opiomelanocortin. Melanotan-2 reproduces its core receptor-binding sequence inside a shortened, stabilised ring. The result is a molecule with a longer effective half-life and higher potency than the parent hormone.
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.