Everything below concerns melanotan-2. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-05-30. 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 II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
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.
| 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 |
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.
Structurally, Melanotan-2 retains the core recognition motif of alpha-melanocyte-stimulating hormone while adding a lactam bridge that links two side chains and constrains the molecule into a ring. This modification lowers susceptibility to enzymatic degradation. The compound acts as an agonist at melanocortin receptors, particularly subtypes associated with melanin production. Because the same receptor family influences several physiological processes, researchers note that its activity is not confined to pigmentation alone. Receptor selectivity continues to be examined in published studies.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its sequence incorporates modified residues that increase potency and extend biological activity relative to the native hormone. The compound binds receptors of the melanocortin family and is examined mainly in laboratory research. It does not occur naturally and exists only as a manufactured chemical entity produced by solid-phase synthesis.
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.
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.
With Robert J. Flaherty's Nanook of the North in 1922, documentary film embraced romanticism. Flaherty filmed a number of heavily staged romantic documentary films during this time period, often showing how his subjects would have lived 100 years earlier and not how they lived right then. For instance, in Nanook of the North, Flaherty did not allow his subjects to shoot a walrus with a nearby shotgun, but had them use a harpoon instead. Some of Flaherty's staging, such as building a roofless igloo for interior shots, was done to accommodate the filming technology of the time. Paramount Pictures tried to repeat the success of Flaherty's Nanook and Moana with two romanticized documentaries, Grass (1925) and Chang (1927), both directed by Merian C. Cooper and Ernest Schoedsack.
Architecturally, all Chipotle restaurants are built using most of the same material finishes (plywood, corrugated metal, stainless steel, exposed ductwork), although each store is unique. The interiors have been described as having an "industrial, sheet metal look". Chipotle has built restaurants using white ceramic tile instead of stainless steel. It costs the company approximately $850,000 to open a new restaurant. When the first Chipotle opened, Steve Ells asked his friend, sculptor Bruce Gueswel, to design the chairs and a styled Mayan king whose face was loosely based on that of civil rights movement leader Martin Luther King Jr., a personal inspiration of Gueswel, for the restaurant. Both items were made from wood and metal. Gueswel has continued to design and build the art and chairs for all subsequent Chipotle restaurants. Most Chipotle locations display a photograph of the original restaurant, which is near the University of Denver campus on Evans Avenue. Instead of a photograph of itself, the original location has a photograph of the Dolly Madison Ice Cream that previously occupied the location. In 2010, Chipotle began opening smaller concept locations that have lower costs of development and occupancy. Chipotle has made arrangements to add solar panels to 75 of its restaurants. Chipotle was the defendant in a lawsuit for failure to comply with the Americans with Disabilities Act (ADA). Maurizio Antoninetti, a customer who used a wheelchair, claimed he was denied the "Chipotle Experience", because he was unable to see the food preparation.
AMBP, APLP2, APP COL6A3, COL7A1, COL28A1 PAPLN, EPPIN, SPINT1, SPINT2, SPINT3, SPINT4 TFPI, TFPI2 WFDC6, WFDC8, WFIKKN1, WFIKKN2 Several plant protease inhibitors of the Kunitz family, the Kunitz-STI protein family, include a beta trefoil fold.
=== Type I Diabetes === It is thought that high glucagon levels and lack of insulin production are the main triggers for the metabolic issues associated with Type I diabetes, in particular maintaining normal blood glucose levels, formation of ketone bodies, and formation of urea. One finding of note is that the glucagon response to hypoglycemia is completely absent in patients with Type I diabetes. Consistently high glucagon concentrations in the blood can lead to diabetic ketoacidosis, which is when ketones from lipid breakdown build up in the blood, which can lead to dangerously low blood glucose levels, low potassium levels, and in extreme cases cerebral edema. It has been proposed that the reason for the high levels of glucagon found in the plasma of patients with Type I diabetes is the absence of beta cells producing insulin and the reciprocal effect this has on delta cells and the secretion of somatostatin.
This article incorporates text from this source, which is in the public domain. Japan: A Country Study. Federal Research Division. Benesch, Oleg (2018). "Castles and the Militarisation of Urban Society in Imperial Japan" (PDF). Transactions of the Royal Historical Society. 28: 107–134. doi:10.1017/S0080440118000063. S2CID 158403519. Archived from the original (PDF) on November 20, 2018. Retrieved November 25, 2018. Earle, Joe (1999). Splendors of Meiji : treasures of imperial Japan : masterpieces from the Khalili Collection. St. Petersburg, Fla.: Broughton International Inc. ISBN 1874780137. OCLC 42476594. Guth, Christine M. E. (2015). "The Meiji era: the ambiguities of modernization". In Jackson, Anna (ed.). Kimono: the art and evolution of Japanese fashion. London: Thames & Hudson. pp. 106–111. ISBN 9780500518021. OCLC 990574229. Iwao, Nagasaki (2015). "Clad in the aesthetics of tradition: from kosode to kimono". In Jackson, Anna (ed.). Kimono: the art and evolution of Japanese fashion. London: Thames & Hudson. pp. 8–11. ISBN 9780500518021. OCLC 990574229. Kublin, Hyman (November 1949). "The "modern" army of early meiji Japan". The Far Eastern Quarterly. 9 (1): 20–41. doi:10.2307/2049123. JSTOR 2049123. S2CID 162485953. Jackson, Anna (2015). "Dress in the Meiji period: change and continuity". In Jackson, Anna (ed.). Kimono: the art and evolution of Japanese fashion. London: Thames & Hudson. pp. 112–151. ISBN 9780500518021. OCLC 990574229. National Diet Library (n.d.). Osaka army arsenal (osaka hohei kosho). Retrieved August 5, 2008.
Sources: en.wikipedia.org
The pathway of wing expansion is regulated by a signal-receptor pathway, where the neurohormone bursicon interacts with its complementary G protein-coupled receptor; this receptor drives one of the G-protein subunits to signal further enzyme activity and results in development in the wing, such as apoptosis and growth. se: sepia – The eye color of the sepia mutant is sepia, a reddish-brown color. In wild-type flies, ommochromes (brown) and drosopterins (red) give the eyes the typical red color. The drosopterins are made via a pathway that involves a pyrimidodiazepine synthase, which is encoded on chromosome 3L. The gene has a premature stop codon in sepia flies, so that the flies cannot produce the pyrimidodiazepine synthase and thus no red pigment, so that the eyes stay sepia. The sepia allele is recessive and thus offspring from sepia flies and homozygous wild type flies, has red eyes. The sepia phenotype does not depend on the sex of the fly. v: vermilion – The vermilion mutants cannot produce the brown ommochromes leaving the red drosopterins so that the eyes are vermilion colored (a radiant red) compared to a wild-type D. melanogaster. The vermilion mutation is sex-linked and recessive. The gene that is defective lies on the X chromosome. The brown ommochromes are synthesised from kynurenine, which is made from tryptophane. Vermilion flies cannot convert tryptophane into kynurenine and thus cannot make ommochromes, either. Vermilion mutants live longer than wild-type flies.
Homopolymers of amino acids (such as polylysine) can adopt α-helical structure at low temperature that is "melted out" at high temperatures. This helix–coil transition was once thought to be analogous to protein denaturation. The statistical mechanics of this transition can be modeled using an elegant transfer matrix method, characterized by two parameters: the propensity to initiate a helix and the propensity to extend a helix.
== Clinical relevance == Pyruvate dehydrogenase deficiency (PDCD) can result from mutations in any of the enzymes or cofactors used to build the complex. Its primary clinical finding is lactic acidosis. Such PDCD mutations, leading to subsequent deficiencies in NAD and FAD production, hinder oxidative phosphorylation processes that are key in aerobic respiration. Thus, acetyl-CoA is instead reduced via anaerobic mechanisms into other molecules like lactate, leading to an excess of bodily lactate and associated neurological pathologies. While pyruvate dehydrogenase deficiency is rare, there are a variety of different genes when mutated or nonfunctional that can induce this deficiency. First, the E1 subunit of pyruvate dehydrogenase contains four different subunits: two alpha subunits designated as E1-alpha and two beta subunits designated as E1-beta. The PDHA1 gene found in the E1-alpha subunits, when mutated, causes 80% of the cases of pyruvate dehydrogenase deficiency because this mutation abridges the E1-alpha protein. Decreased functional E1 alpha prevents pyruvate dehydrogenase from sufficiently binding to pyruvate, thus reducing the activity of the overall complex. When the PDHB gene found in the E1 beta subunit of the complex is mutated, this also leads to pyruvate dehydrogenase deficiency.
== Prognosis == Mortality in affected felid litters varies between 20 and 100%. Mortality of FPLV is 25–90% in domestic cats with the acute form of the disease and up to 100% in cats with peracute disease. In 2010, a retrospective study of 244 infected cats showed that "leukocyte and thrombocyte counts as well as serum albumin and potassium concentrations at presentation are prognostic indicators in cats with panleukopenia, whereas vaccination status, age, clinical signs, and housing conditions are not." A survival rate of about 50% has been reported with supportive therapies. Cats with FPLV that survive the first five days of treatment usually recover; however, the decrease in the cat's white blood cells compromises its immune system, leaving it vulnerable to secondary infection. Lifelong immunity is thought to follow recovery from disease, and a carrier state of the disease has never been identified.
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.
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.