The short version of Melanotan II fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-04-10 and is reviewed periodically as new material appears.
Identity and purity are assessed with chromatographic and mass spectrometric techniques. Reversed-phase high-performance liquid chromatography separates the target peptide from related impurities and degradation products, and the resulting retention time is compared against a reference standard. Mass spectrometry, often coupled to liquid chromatography, confirms molecular mass. Amino acid analysis or peptide mapping can provide additional sequence-level confirmation when required. Results are only as reliable as the reference materials used alongside them.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Solid-state storage | -20 degrees Celsius or lower | Desiccated and protected from light |
| Solution stability | Short and method-dependent | Confirm by stability testing |
| Purity assessment | Reversed-phase HPLC | Reported as area percent |
| Identity confirmation | LC-MS or comparable method | Mass match against expected value |
| Common synonyms | MT-II; melanotan II | Informal and catalogue names |
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.
Regulatory treatment of this peptide varies by country. It holds no marketing authorization as a medicine in the United States, the European Union, or most other jurisdictions. Some countries classify products containing it as prescription-only or unlicensed medicines, which restricts lawful supply. Authorities have issued public notices warning that unregulated products may contain undeclared or incorrect ingredients. The molecule also appears on prohibited lists for competitive sport. These measures address supply oversight rather than any approved therapeutic role.
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.
Melanotan II is a synthetic cyclic heptapeptide analog derived from the core sequence of alpha-melanocyte-stimulating hormone. Researchers at the University of Arizona synthesized it during the 1980s while studying pigmentation and appetite signaling. The compound is not an approved medicine in any major jurisdiction and appears mainly in laboratory and research-chemical settings. Its structure incorporates a lactam bridge between side chains, which constrains the ring and slows enzymatic breakdown relative to the natural hormone.
Regulatory treatment varies by country. In the United States the peptide is not approved as a medicine, and products offered for human use may be treated as unapproved new drugs; some states also restrict sale. Australia, the United Kingdom, and European Union member states apply comparable restrictions to unapproved peptide products. Border agencies have seized shipments labelled as research chemicals. Classification may change over time, and the legal position for personal importation is not clearly settled in most published guidance.
Lyophilised melanotan-2 is supplied as a solid, which is more stable than a solution. The material is hygroscopic, so weighing is done quickly, in low humidity, with the container kept sealed. Reconstitution usually uses water for injection or bacteriostatic water, added down the wall of the vial to limit foaming. A reconstituted solution is held at 2 to 8 °C and kept away from light. Repeated freezing and thawing of the same vial is avoided because ice crystal formation and concentration effects degrade the peptide.
Seafood fraud has led to widespread keriorrhea due to mislabeled escolar, mercury poisoning from products marketed as safe for pregnant women, and hospitalisation and neurological damage due to mislabeled pufferfish. For example, a 2014 study published in PLOS One found that 15% of MSC certified Patagonian toothfish originated from uncertified and mercury polluted fisheries. These fishery-stock substitutions had 100% more mercury than their genuine counterparts, "vastly exceeding" limits in Canada, New Zealand, and Australia.
Aristotle in 350 BC in his History of animals noted the habits of bird migration, moulting, egg laying, and lifespans, as well as compiling a list of 170 different bird species. However, he also introduced and propagated several myths, such as the idea that swallows hibernated in winter, although he noted that cranes migrated from the steppes of Scythia to the marshes at the headwaters of the Nile. The idea of swallow hibernation became so well established that even as late as in 1878, Elliott Coues could list as many as 182 contemporary publications dealing with the hibernation of swallows and little published evidence to contradict the theory. Similar misconceptions existed regarding the breeding of barnacle geese. Their nests had not been seen, and they were believed to grow by transformations of goose barnacles, an idea that became prevalent from around the 11th century and noted by Bishop Giraldus Cambrensis (Gerald of Wales) in Topographia Hiberniae (1187). Around 77 AD, Pliny the Elder described birds, among other creatures, in his Historia Naturalis. The earliest record of falconry comes from the reign of Sargon II (722–705 BC) in Assyria. Falconry is thought to have made its entry to Europe only after 400 AD, brought in from the east after invasions by the Huns and Alans. Starting from the eighth century, numerous Arabic works on the subject and general ornithology were written, as well as translations of the works of ancient writers from Greek and Syriac.
=== Vitamin B9 (Folate) === There are many naturally occurring vitamers of vitamin B9, i.e., folate, found in minimally processed foods. Sometimes referred to as "food folates", these vitamers are characterized as pteroylpolyglutamates and contain between one and six additional glutamate molecules compared to folic acid. Folic acid, chemically described as pteroylmonoglutamic acid, is another vitamer of vitamin B9. Though rarely found in minimally processed foods, it is the primary form of vitamin B9 added to fortified foods and many dietary supplements. Folic acid and food folates are absorbed and metabolized by different pathways. After digestion, food folates are converted in the small intestine to 5-methyltetrahydrofolic acid, a biologically active vitamer of vitamin B9. Folic acid is absorbed and transported in the bloodstream to the liver, where it is converted to tetrahydrofolate, a second biologically active vitamer, by dihydrofolate reductase. The liver has a limited capacity to metabolize folic acid into tetrahydrofolate. Any folic acid that is not converted to tetrahydrofolate in the liver remains in the blood until it is either metabolized in the liver or excreted by the kidney. Folic acid that remains in the blood stream is considered unmetabolized folic acid. Since the introduction of mandatory folic acid fortification in the US, most people have a variable amount of unmetabolized folic acid circulating in their blood.
ubiquitin (Ub) A small protein of 76 amino acids found in great quantities (ubiquitously) in all eukaryotic cells, employed chiefly as a post-translational protein tag, by which its C-terminal glycine residue is covalently bonded to electrically charged residues within other proteins or polypeptides, a process known as ubiquitination. Ubiquitin tags have functions in the heat-shock response, protein sorting, proteolysis, membrane trafficking, cell signaling, regulation of the cell cycle, X chromosome inactivation, and histone modification, among others.
=== Davis Cup === Zverev made his Davis Cup debut for Germany against the Czech Republic in 2016. He faced No. 7 Tomáš Berdych in his debut match and took a two sets to one lead before ultimately losing in five sets. After the Czech Republic won the doubles rubber while Kohlschreiber won both singles matches, Zverev faced Lukáš Rosol in a decisive fifth rubber. Rosol won the match easily to send the Czech Republic into the next round. In the 2017 against Belgium, Zverev recorded his first career match win in the competition against Arthur De Greef, but lost the doubles rubber with his brother as well as his second singles match to Steve Darcis. Belgium won the tie 4–1. Zverev won his first Davis Cup tie in 2018, winning both of his singles matches against Alex de Minaur and Kyrgios to lead Germany to a 3–1 victory over Australia. In the quarterfinals, Germany took a 2–1 lead against Spain behind Zverev's win over David Ferrer and a victory in doubles. However, Spain ultimately won the tie on the final day after Zverev was unable to defeat Nadal and Kohlschreiber lost a tight five-set match to Ferrer. In 2019, the format of the Davis Cup was changed to have eighteen countries competing in the finals over a single week in November, all but six of which were decided through a qualifying round in February. Germany was placed in the qualifying round and drawn against Hungary. Zverev participated and won both of his singles matches as Germany won the tie 5–0. He did not participate in the finals in November, in which Germany lost in the quarterfinals.
Sources: en.wikipedia.org
The Terek Cossack Host was created in 1577 by free Cossacks resettling from the Volga to the Terek River. Local Terek Cossacks joined this host later. In 1792, the host was included in the Caucasus Line Cossack Host, from which it separated again in 1860, with Vladikavkaz as its capital. In 1916, the population of the host was 255,000, within an area of 1.9 million desyatinas.
=== Replication cycle === Virus infections start when viral particles bind to host surface cellular receptors. Protein modelling experiments on the spike protein of the virus soon suggested that SARS‑CoV‑2 has sufficient affinity to the receptor angiotensin converting enzyme 2 (ACE2) on human cells to use them as a mechanism of cell entry. By 22 January 2020, a group in China working with the full virus genome and a group in the United States using reverse genetics methods independently and experimentally demonstrated that ACE2 could act as the receptor for SARS‑CoV‑2. Studies have shown that SARS‑CoV‑2 has a higher affinity to human ACE2 than the original SARS virus. SARS‑CoV‑2 may also use basigin to assist in cell entry. Initial spike protein priming by transmembrane protease, serine 2 (TMPRSS2) is essential for entry of SARS‑CoV‑2. The host protein neuropilin 1 (NRP1) may aid the virus in host cell entry using ACE2. After a SARS‑CoV‑2 virion attaches to a target cell, the cell's TMPRSS2 cuts open the spike protein of the virus, exposing a fusion peptide in the S2 subunit, and the host receptor ACE2. After fusion, an endosome forms around the virion, separating it from the rest of the host cell. The virion escapes when the pH of the endosome drops or when cathepsin, a host cysteine protease, cleaves it. The virion then releases RNA into the cell and forces the cell to produce and disseminate copies of the virus, which infect more cells. SARS‑CoV‑2 produces at least three virulence factors that promote shedding of new virions from host cells and inhibit immune response.
== Mechanism of resistance == Streptogramin resistance is mediated through enzymatic drug inactivation, efflux or active transport of drug out of the cell, and most commonly, conformational alterations in ribosomal target binding sites. Enzymatic drug inactivation may occur in staphylococcal and enterococcal species through production of dalfopristin-inactivating acetyltransferase or quinupristin-inactivating hydrolase. Efflux or active transport of the drug may occur in coagulase-negative staphylococci and Enterococcus faecium. Constitutive ribosome modification has been seen in staphylococci with resistance seen in quinupristin only. While resistance to dalfopristin may be conferred via a single point of mutation, quinupristin/dalfopristin offers the benefit of requiring multiple points of mutation targeting both dalfopristin and quinupristin components to confer drug resistance. Comparatively, only 2-5% of staphylococcal isolates collected in France show resistance to a related streptogramin, pristinamycin, in over 35 years of use.
== Interactions == The effect of the interfacial layer is clearly seen in the interactions between nanoparticles. These interactions can be modelled using the DLVO theory. Classically this theory states that the potential of a particle is the sum of the electrostatic and van der Waals interaction. This is theory has proven to be very accurate for almost all Colloidal particles, but cannot describe all the interactions measured for nanoparticles. Therefore this theory has been extended with the so called non-DLVO terms. In this extension the hydration force, hydrofobic force, steric force and bridging force are also considered, resulting in a total potential as follows:
== Treatment == Treatment is the same as for patients with sickle cell disease. Patients may receive hydroxyurea to induce the protective effects of increased fetal hemoglobin production. They may also benefit from blood transfusions especially during vaso-occlusive crises. Patients may be offered chemoprophylaxis with penicillin. They may have splenic dysfunction and splenectomy is frequently performed. Vaccination against encapsulated bacteria including Streptococcus pneumoniae is recommended.
Sources: en.wikipedia.org
Laboratory confirmation typically combines retention time matching on a chromatographic system with mass measurement. A reference standard of known identity is needed for a meaningful comparison. Sequence-level techniques can add further confirmation.
There is no single harmonised standard governing these products, and manufacturing conditions differ. Impurities may include truncated sequences, oxidation products, residual solvents, and counter-ions. Independent testing is often the only way to characterise a given lot.
Reported studies have looked at pigmentation, photoprotection, and metabolic or appetite-related endpoints in small experimental settings. Much of the evidence base is early-stage and limited in size. Questions about long-term effects and clinical relevance remain open.
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.