This is a working overview of alpha-MSH analogue, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-01-09. Anything still debated is marked as such rather than presented as settled.
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.
Research interest has centred on photoprotection and pigmentation, with a smaller body of work on appetite and sexual function. Published human data remain limited to small, frequently uncontrolled studies, and the compound has never received marketing approval from a national medicines regulator. Most laboratory work treats it as a pharmacological tool for probing melanocortin signalling in cell culture or animal models. Whether pigmentation changes observed in people translate into measurable protection against ultraviolet-induced DNA damage remains an open question.
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.
Melanotan-2 appears on the World Anti-Doping Agency prohibited list within the peptide hormone class, and several national regulators treat it as an unapproved prescription substance. Some countries restrict importation or sale for personal use. Because the compound is widely traded as a research chemical, the practical legal picture differs between jurisdictions and shifts over time. Human safety data covering long periods are limited, and whether repeated pigmentation changes carry any lasting risk to melanocytes remains an open question.
Freeze-dried melanotan-2 is normally kept as a desiccated powder at minus twenty degrees Celsius or lower, shielded from light and moisture. Peptides of this size degrade through hydrolysis, oxidation and deamidation, and each pathway accelerates as temperature and water activity rise. Repeated freeze-thaw cycles promote aggregation and loss of material, so aliquoting a stock solution before freezing is standard laboratory practice. Once dissolved, the solution is markedly less stable than the powder. In laboratory work, solutions are generally refrigerated and used within days rather than kept for months.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, which separates the target peptide from truncated or oxidised impurities. Mass spectrometry, most often coupled to liquid chromatography, confirms molecular mass and detects substitutions that chromatography alone may miss. Amino acid analysis and peptide mapping supply additional structural evidence, while nuclear magnetic resonance is reserved for full structural confirmation. Laboratories that examine samples sold online report wide variation in actual content, with some vials containing little or none of the labelled material.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Melanotan II; MT-II; N-acetyl-norleucyl-cyclo[Asp-His-D-Phe-Arg-Trp-Lys] amide | Naming follows peptide convention; the numeral distinguishes it from melanotan-1 |
| Molecular formula | C50H69N15O9 | Includes the lactam bridge; no counter-ion assumed |
| Monoisotopic mass | 1023.53 Da | Free base; salts and counter-ions shift the observed value |
| Appearance | White to off-white lyophilised powder | Batch-to-batch colour variation is not itself proof of impurity |
| Typical analytical method | RP-HPLC purity determination with ESI-MS identity confirmation | Retention time alone does not establish sequence identity |
The peptide was developed during the 1980s by researchers investigating melanocortin signalling and skin pigmentation pathways. Early work focused on analogues of alpha-melanocyte-stimulating hormone that would resist enzymatic breakdown more effectively than the parent molecule. Melanotan-2 emerged from that programme as a shortened, cyclised variant. Reports describing its synthesis and receptor activity later appeared in the scientific literature. Commercial availability grew through unregulated channels rather than through pharmaceutical approval.
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.
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.
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.
==== Non-volatile residue ==== Another type of contamination in UPW is dissolved inorganic material, primarily silica. Any dissolved inorganic material has the potential to remain on the wafer as the UPW dries. Nonvolatile material can be detected by using nebulizer to create small droplets liquid suspended in a stream of gas. These droplets are dried an aerosol of non-volatile residue particles that can be counted by light scattering techniques.
Ruminant animals can obtain protein from at least some forms of non-protein nitrogen (NPN) through fermentation by their rumen bacteria, hence NPN is often added to their diet to supplement protein. Nonruminants such as cats, dogs and pigs (and humans) cannot utilize NPN. NPN are given to ruminants in the form of pelleted urea, ammonium phosphate and/or biuret. Sometimes slightly polymerized special urea-formaldehyde resin or a mixture of urea and formaldehyde (both are also known as formaldehyde-treated urea) is used in place of urea, because the former provides a better control on the nitrogen release. This practice is carried out in China and other countries, such as Finland, India and France. Cyanuric acid has also been used as NPN. For example, Archer Daniels Midland manufactures an NPN supplement for cattle, which contains biuret, triuret, cyanuric acid and urea. FDA permits a certain amount of cyanuric acid to be present in some additives used in animal feed and also drinking water. Melamine use as NPN for cattle was described in a 1958 patent. In 1978, however, a study concluded that melamine "may not be an acceptable nonprotein N source for ruminants", because its hydrolysis in cattle is slower and less complete than other nitrogen sources such as cottonseed meal and urea. In China, it is known that ground urea-formaldehyde resin is a common adulterant in feed for non-ruminants. Domestically it is often sold under the euphemism "protein essence" (蛋白精) and is described as "one kind of new proteinnitrogen feed additive".
== History == Peak Scientific was established by its founder and current chairman Robin MacGeachy in 1992 originally operating as an air compressor distributor until 1997 when the company was registered to manufacture gas generators on a 10,000 square foot facility at Inchinnan. It was not until 2004 when Robin MacGeachy fully acquired the business. Timeline 1992 – Business initially established as a distributor of air compressors 1997 – Peak Scientific established to manufacture gas generators 2005 – First international office opens in North America 2007 – India office opens 2008 – Africa office opens 2010 – Mexico, China and Hong Kong offices open 2011 – Australia office opens 2012 – Offices in Germany, Brazil, Japan and Singapore open 2013 – Offices in Canada, France and Spain open 2015 – New offices open in India and Abu Dhabi 2016 – Third office in India opens 2017 – Business is registered in Ireland and Vietnam 2018 – Office in Korea opens
The WMH also examined unmet needs for treatment in strata defined by the seriousness of mental disorders. Their research showed that "the number of respondents using any 12-month mental health service was generally lower in developing than in developed countries, and the proportion receiving services tended to correspond to countries' percentages of gross domestic product spent on health care". High levels of unmet need worldwide are not surprising, since WHO Project ATLAS' findings of much lower mental health expenditures than was suggested by the magnitude of burdens from mental illnesses. Generally, unmet needs in low-income and middle-income countries might be attributable to these nations spending reduced amounts (usually <1%) of already diminished health budgets on mental health care, and they rely heavily on out-of-pocket spending by citizens who are ill-equipped for it".
== Labeled expiration date versus true expiration == Manufacturers print expiration dates on drug bottle labels. The labeled expiration date is a manufacturer's promise for a time until which the drug will have full efficacy and be safe as manufactured. The labeled expiration date is not an indication of when a drug has become ineffective or unsafe to use. Many drugs are effective for years after their expiration dates. However, it is difficult for anyone including researchers and physicians to find information to verify how much any given drug will degrade in efficacy or become unsafe over time. Drug manufacturers never support the use of drugs after the expiration date because that could make them liable if something went wrong. The expiration date printed on drug packaging will differ from the date when the drug will become ineffective. Before the true expiration of a drug, its active ingredient will retain its potency. Also before expiration, no components of the drug will degrade to become harmful. Since products continually change over time, the characteristics of any drug are not unchanging but instead estimated with assay measurements to be within the specification required by the government regulator where the drug is sold. As a general estimate, a drug is deemed to be unfit for use when 10% of the active ingredient is degraded. Before choosing an expiration date to print the manufacturer must decide a true expiration date.
Sources: en.wikipedia.org
== Properties == This compound is a yellow crystalline powder with moderate human toxicity. It shows two polymorphs in the crystalline state. The alpha-form is colorless pillars, unstable at room temperature, and stable toward sunlight. The beta-form is yellow pillars, stable at room temperature, and gradually turns red upon irradiation of sunlight. Usually 4-nitrophenol exists as a mixture of these two forms.
The authors concluded that the effects previously attributed to oxazepam were instead likely caused by a combination of fish being stressed by human handling and small aquaria, followed by being exposed to a novel environment.
Biden earned a Juris Doctor from Syracuse University College of Law in 1968. In his first year of law school, he failed a course because he plagiarized a law review article, but the failing grade was later stricken. His grades were relatively poor, and he graduated 76th in a class of 85. He was admitted to the Delaware bar in 1969. Biden clerked at a law firm headed by prominent local Republican William Prickett in 1968 and self-identified as a Republican. He disliked incumbent Democratic Delaware governor Charles L. Terry's conservative racial politics and supported a more liberal Republican, Russell W. Peterson, who defeated Terry in 1968. Local Republicans attempted to recruit Biden, but he registered as an independent because of his distaste for Republican presidential candidate Richard Nixon.
In March 2025, the Belgian Prosecutor's Office requested the lifting of parliamentary immunity for Elisabetta Gualmini and Alessandra Moretti. In December 2025, the European Parliament voted in favour of removing Moretti's immunity, but against removing that of Gualmini. As of March 2026, no trial date had been set in the case. Defence lawyers had lodged a complaint about the way the investigation had been conducted; in February 2026, the Court of Appeal ruled that there had been no significant flaws in the investigation and that the prosecution could continue.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, containing seven amino acids with a lactam ring and a D-configured phenylalanine residue. It is supplied as a lyophilised powder for laboratory research.
The natural hormone is a linear tridecapeptide that is rapidly degraded in circulation. Melanotan-2 is shortened, cyclised, N-terminally acetylated, and carries a D-amino acid substitution, all of which slow enzymatic breakdown.
No national medicines regulator has approved melanotan-2 for therapeutic or cosmetic use. In several jurisdictions it is treated as an unapproved prescription medicine, and its legal classification differs from country to country.
The lyophilised solid is best kept cold, dry and dark, typically at minus twenty degrees Celsius. Moisture and repeated warming cycles are the main causes of degradation. Solutions prepared from the powder are less stable and are normally used quickly.