Everything below concerns cyclic heptapeptide. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-06-28. Where a claim depends on a specific study, the study is described rather than over-claimed.
Published research on the compound remains limited. Much of the human data comes from small, early-stage studies rather than large controlled trials, and several questions about effects and variability between individuals remain open. Investigators have examined receptor activity, pigment pathways, and related physiological responses in laboratory and animal models. Findings from those models do not automatically translate to human outcomes. Reviews frequently note the scarcity of rigorous clinical evidence and call for better-characterized study material.
Because the substance circulates mainly through informal markets, verification is a recurring theme in technical discussion. Independent analyses have found that labeled content and actual content can diverge, and that purity varies between samples. Analytical laboratories use reversed-phase chromatography to separate components and mass spectrometry to confirm identity. Isotope-labeled internal standards improve quantification in complex matrices. Such methods describe what a sample contains but say nothing about its sterility, lawful status, or suitability for any use. Open questions remain about how consistently testing is applied across the supply chain.
Human data remain limited and mostly short-term. Reports describe small trials and observational accounts rather than large controlled studies, so questions about dose-response relationships and long-term effects on melanocytes stay open. Whether repeated exposure alters naevus behaviour is not settled in the published record. Researchers also note that self-administered use outside clinical settings makes actual exposure difficult to quantify. Statements about efficacy and safety should therefore be read as preliminary rather than established.
Melanotan II is a synthetic cyclic heptapeptide that acts as an agonist at melanocortin receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide involved in pigment production. The analogue carries a lactam bridge that constrains the ring and slows enzymatic breakdown relative to the native hormone. In research literature it appears under several abbreviations, and naming conventions are not fully standardized. Published descriptions usually place it within the broader melanocortin agonist family.
Receptor binding at MC1R on melanocytes raises intracellular cyclic AMP and increases expression of tyrosinase and related enzymes. The downstream result is greater synthesis of eumelanin, the dark pigment, without ultraviolet exposure acting as the trigger. The compound is not selective, however, and also engages MC3R, MC4R and MC5R, which are expressed in the central nervous system and elsewhere. That lack of selectivity is the explanation usually offered for effects reported outside pigmentation, including appetite suppression and nausea. Selectivity remains a central theme in comparative studies of related peptides.
| Property | Value | Notes |
|---|---|---|
| Regulatory status | Not approved as a medicine | No marketing authorization in major jurisdictions |
| Scheduling example | Prescription-only supply in some countries | Handled as an unlicensed medicine where restricted |
| Sports classification | Prohibited peptide | Appears on anti-doping prohibited lists |
| Reported presentation | Lyophilized vial | Nominal content varies between vendors |
| Detection approach | Liquid chromatography–tandem mass spectrometry | Used in anti-doping and forensic testing |
Independent verification is central to quality control because the compound is not produced under pharmaceutical manufacturing standards. Third-party laboratories can measure purity, identity, residual solvents, and microbial contamination, though the scope of testing varies between services. Reported analyses of vendor samples have shown batch-to-batch variation in peptide content and the presence of truncated or oxidized species. How much of this variation reflects synthesis conditions versus storage and shipping is not well characterized. No harmonized reference standard exists for the material as sold.
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.
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.
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.
==== Re-chilling brands ==== The iron is then returned to the coolant bath. Once used, a branding iron in its coolant takes between two and ten minutes to reach its working temperature again. For this reason, several irons are usually cooled at the same time to permit rapid branding of more than one animal or the convenient duplication of alphanumeric characters such as "AA" or "33". So long as dry ice remains in an alcohol bath, irons submerged in it will eventually reach working temperatures.
Although protons were originally considered to be elementary particles, in the modern Standard Model of particle physics, protons are known to be composite particles, containing three valence quarks, and together with neutrons are now classified as hadrons. Protons are composed of two up quarks of charge +2/3e each, and one down quark of charge −1/3e. The rest masses of quarks contribute only about 1% of a proton's mass. The remainder of a proton's mass is due to quantum chromodynamics binding energy, which includes the kinetic energy of the quarks and the energy of the gluon fields that bind the quarks together. The proton charge radius is around 0.841 fm but two different kinds of measurements give slightly different values. At sufficiently low temperatures and kinetic energies, free protons will bind electrons in any matter they traverse. Free protons are routinely used for accelerators for proton therapy or various particle physics experiments, with the most powerful example being the Large Hadron Collider.
In 1839, the Daoguang Emperor rejected proposals to legalise and tax opium and ordered imperial commissioner Lin Zexu to eradicate the opium trade. The commissioner destroyed opium stockpiles and halted all foreign trade, triggering a British military response and the First Opium War. The Qing surrendered early in the war and ceded Hong Kong Island in the Convention of Chuenpi, signed by Charles Elliot and Qishan. British forces began controlling Hong Kong shortly after the signing of the convention, on 26 January 1841. However, both countries were dissatisfied and did not ratify the agreement. After more than a year of further hostilities, Hong Kong Island was formally ceded to the United Kingdom in the 1842 Treaty of Nanking. Administrative infrastructure was quickly built by early 1842, but piracy, disease, and hostile Qing policies initially prevented the government from attracting commerce. Conditions on the island improved during the Taiping Rebellion in the 1850s, when many Chinese refugees, including wealthy merchants, fled mainland turbulence and settled in the colony. Further tensions between the British and Qing over the opium trade escalated into the Second Opium War. The Qing were again defeated and were forced to give up Kowloon Peninsula and Stonecutters Island in the Convention of Peking. By the end of this war, Hong Kong had evolved from a transient colonial outpost into a major entrepôt. Rapid economic improvement during the 1850s attracted foreign investment, as potential stakeholders became more confident in Hong Kong's future.
The news began spreading immediately: the West German Deutsche Presse-Agentur issued a bulletin at 19:04 which reported that East German citizens would be able to cross the inner German border "immediately". Excerpts from Schabowski's press conference were broadcast on West Germany's two main news programs that night—at 19:17 on ZDF's heute, which came on the air as the press conference was ending, and as the lead story at 20:00 on ARD's Tagesschau. As ARD and ZDF had broadcast to nearly all of East Germany since the late 1950s, were far more widely viewed than the East German channels, and had become accepted by the East German authorities, this is how most of the population heard the news. Later that night, on ARD's Tagesthemen, anchorman Hanns Joachim Friedrichs proclaimed, "This 9 November is a historic day. The GDR has announced that, starting immediately, its borders are open to everyone. The gates in the Wall stand open wide." In 2009, Ehrman claimed that a member of the Central Committee had called him and urged him to ask about the travel law during the press conference, but Schabowski called that absurd. Ehrman later recanted this statement in a 2014 interview with an Austrian journalist, admitting that the caller was Günter Pötschke, head of the East German news agency ADN, and he only asked if Ehrman would attend the press conference.
January 24 Trump threatens Canada with 100% tariffs on all goods if the country's prime minister Mark Carney strikes a trade deal with China. Killing of Alex Pretti: A 37-year-old man is shot and killed by United States Immigration and Customs Enforcement agents in Minneapolis, Minnesota. One person is killed and 14 others are injured in a gas explosion and multiple-alarm fire at a 17-story apartment building in the Bronx, New York City. January 25 Over a million people are without power across the South and at least 10,000 flights are canceled due to the winter storm. Six people are killed when a Bombardier Challenger 650 aircraft crashes at Bangor International Airport in Maine. January 27 – Representative Ilhan Omar is attacked during a town hall meeting in Minneapolis when an audience member sprays a chemical substance at her. A 55-year-old man is arrested and charged with third-degree assault, while Omar herself is uninjured. January 28 FBI investigation into the 2020 United States presidential election in Georgia: The Federal Bureau of Investigation raids the election center in Fulton County, Georgia. Amazon announces 16,000 job layoffs in its second round of corporate reduction. January 29 – Journalist and former CNN host Don Lemon is arrested by federal authorities after he reported on a protest inside a church in St. Paul, Minnesota earlier in the month. January 30 Three million pages related to the Epstein Files, including 2,000 videos and 180,000 images, are released to the public, implicating many high-profile public figures worldwide.
Sources: en.wikipedia.org
Before isolating the gas, they had determined that nitrogen produced from chemical compounds was 0.5% lighter than nitrogen from the atmosphere. The difference was slight, but it was important enough to attract their attention for many months. They concluded that there was another gas in the air mixed in with the nitrogen. Argon was also encountered in 1882 through independent research of H. F. Newall and W. N. Hartley. Each observed new lines in the emission spectrum of air that did not match known elements. Prior to 1957, the symbol for argon was "A". This was changed to Ar after the International Union of Pure and Applied Chemistry published the work Nomenclature of Inorganic Chemistry in 1957.
== Chemistry == Metformin hydrochloride (1,1-dimethylbiguanide hydrochloride) is freely soluble in water, slightly soluble in ethanol, but almost insoluble in acetone, ether, or chloroform. The pKa of metformin is 12.4. The usual synthesis of metformin, originally described in 1922, involves the one-pot reaction of a heated solution of dimethylamine hydrochloride and 2-cyanoguanidine.
Nicotine is a very hygroscopic, colorless to pale yellow, oily liquid that gradually turns brown on exposure to air or light. It develops a characteristic pungent, fishy odor of pyridine and has an acrid burning taste. Pure nicotine tastes "terrible". It is very soluble in alcohol, chloroform, ether, light petroleum, kerosene, or oils. It is miscible with water in its neutral amine base form between 60 °C and 210 °C. It is a dibasic nitrogenous base, having Kb1=1×10−6, Kb2=1×10−11. It readily forms ammonium salts with acids that are usually solid and water-soluble. Its flash point is 95 °C, and its auto-ignition temperature is 244 °C. Nicotine is volatile (vapor pressure 5.5 Pa at 25 °C) On exposure to ultraviolet light or various oxidizing agents, nicotine is converted to nicotine oxide, nicotinic acid (niacin, a B3 vitamer), and methylamine. Anabasine is a structural isomer of nicotine, as both compounds have the molecular formula C10H14N2.
== Role in cardiac development and vasculature == HB-EGF binding and activation of EGF receptors plays a critical role during cardiac valve tissue development and the maintenance of normal heart function in adults. During valve tissue development the interaction of HB-EGF with EGF receptors and heparan sulfate proteoglycans is essential for the prevention of malformation of valves due to enlargement. In the vascular system areas of disturbed flow show upregulation of HB-EGF with promotion of vascular lesions, atherogenesis, and hyperplasia of intimal tissue in vessels. The flow disturbance remodeling of the vascular tissues due to HB-EGF expression contributes to aortic valve disease, peripheral vascular disease, and conduit stenosis.
For three years, there was an indecisive struggle between the heterogeneous Assembly and the president, who was silently awaiting his opportunity. He chose as his ministers men with little inclination towards republicanism, with a preference for Orléanists, the chief of whom was Odilon Barrot. In order to strengthen his position, he endeavoured to conciliate the reactionary parties, without committing himself to any of them. The chief instance of this was the expedition to Rome voted by the Catholics, to restore the temporal authority of Pope Pius IX, who had fled Rome in fear of the nationalists and republicans. (Garibaldi and Mazzini had been elected to a Constitutional Assembly.) The pope called for international intervention to restore him in his temporal power. The French president moved to establish the power and prestige of France against that of Austria, as beginning the work of European renovation and reconstruction which he already looked upon as his mission. French troops under Oudinot marched into Rome. This provoked an insurrection in Paris in favour of the Roman Republic, that of the Château d'Eau, which was crushed on 13 June 1849. On the other hand, when the pope, though only just restored, began to yield to the general movement of reaction, the president demanded that he should set up a Liberal government. The pope's dilatory reply having been accepted by the French ministry, the president replaced it on 1 November, by the Fould-Rocher cabinet.
Sources: en.wikipedia.org
Only a small number of early-stage human studies have been reported, and most were limited in size and duration. No large late-stage program has established a general efficacy or safety profile. The evidence base is therefore thin compared with approved medicines.
The peptide is listed as prohibited in competitive sport, so laboratories develop detection methods and monitor for its presence. Its appearance in enforcement reports reflects that classification rather than any approved athletic use. Analytical work in this area focuses on identifying the molecule and its breakdown products in biological samples.
Chromatographic separation combined with mass spectrometry identifies the peptide and estimates its amount in a sample. Testing can confirm whether the expected molecule is present and at what concentration. It cannot establish how a product was manufactured or whether it meets any purity standard.
It is a synthetic cyclic heptapeptide and a non-selective melanocortin receptor agonist. Structurally it is modelled on alpha-melanocyte-stimulating hormone, a peptide that occurs naturally in the body.