Everything below concerns reversed-phase HPLC. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-02-05. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
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.
The nuclear plants have further been questioned as a source of the cases due to comparison to the Savannah River Site in the United States. Despite the release of radiation at the Savannah River Site, there is no increase in cases of leukemia around it. Alternative hypotheses for the cause of the cases have included electromagnetic fields, parental radiation exposure before conception, other carcinogens, and benzene exposure; however, none have been supported by the existing evidence. Intriguingly, a larger case-control study in Lower Saxony found a correlation between the "untrained immune system" (as judged as contact with other children, vaccinations, etc.) and leukemia risk, suggested that an immature immune system that has not been challenged is at greater risk for developing malignancy, possibly secondary to an undetermined environment factor.
== Uses == In the 1970s and 1980s, the proportionately largest use of these polymers was in water treatment. The next major application by weight is additives for pulp processing and papermaking. About 30% of polyacrylamide is used in the oil and mineral industries.
=== Saturday Night Live === In September 2005, Samberg joined Saturday Night Live as a featured player and writer. Though his live sketch roles were limited in his first year, he appeared in many prerecorded sketches including commercial parodies and various other filmed segments. On December 17, 2005, he co-starred with castmate Chris Parnell in the Digital Short show "Lazy Sunday," a hip hop song about a quest to see the film The Chronicles of Narnia: The Lion, the Witch and the Wardrobe. The short became an Internet phenomenon and garnered Samberg significant media and public attention. Acclaim continued, especially for "Dick in a Box," a duet with Justin Timberlake that won a Creative Arts Emmy for Outstanding Original Music and Lyrics. The video for his comedy troupe's collaboration with T-Pain, "I'm on a Boat," had over 56 million views on YouTube, after debuting on February 7, 2009. The song was nominated for a Grammy Award. Another digital short, "Motherlover," also featuring Timberlake, was released on May 10, 2009, to commemorate Mother's Day. Outside of his prerecorded segments, he participated in recurring live segments, such as his Blizzard Man sketch. On June 1, 2012, Samberg's spokesperson announced that Samberg had left the show. He returned to the show to host the Season 39 finale in 2014 and to star in the 40th anniversary special's Digital Short. He later returned in Season 50 to portray Doug Emhoff in the run up to the 2024 election, as well as providing some additional Digital Shorts.
=== Theatre === Doillon, alongside director Michel Didym, created a show based on letters written by French authors and singers (Louis-Ferdinand Celine, Marcel Proust and Édith Piaf), and monologues. She toured French-speaking theatres throughout Europe by herself for over two years. In 2010, Doillon started working with director Arthur Nauzyciel on Samuel Beckett's one sentence monologue "L'Image" in the National Theatre of Orléans. Alongside dancer Damien Jalet and conceptual musician Meelice, they performed throughout France and in New York for the Crossing the Line Festival. In 2017, for the National Theatre of Rennes, Doillon performed "L'Image" directed by Nauzyciel for a week. Doillon has also collaborated on various performances (Paroles d'Exil/Musique Interdite with the French National Orchestra, Calamity Jane with singer/ musician John Mitchell and as a reader for many French-literature festivals).
== Further reading == Schill, Gottfried (1971). Catenanes, Rotaxanes, and Knots (1st ed.). Academic Press. p. 204. ISBN 978-1-4832-7566-6. G. A. Breault, C. A. Hunter and P. C. Mayers (1999). "Supramolecular topology". Tetrahedron. 55 (17): 5265–5293. doi:10.1016/S0040-4020(99)00282-3.
Sources: en.wikipedia.org
PRRT radiopharmaceuticals are constructed with three components; the radionuclide, chelator, and somatostatin analogue (peptide). The radionuclide delivers the actual therapeutic effect (or emission, such as photons, for imaging). The chelator is the essential link between the radionuclide and peptide. For 177Lu and 90Y this is typically DOTA (tetracarboxylic acid, and its variants) and DTPA (pentetic acid) for 111In. Other chelators known as NOTA (triazacyclononane triacetic acid) and HYNIC (hydrazinonicotinamide) have also been experimented with, albeit more for imaging applications. The somatostatin analogue affects biodistribution of the radionuclide, and therefore how effectively any treatment effect can be targeted. Changes affect which somatostatin receptor is most strongly targeted. For example, DOTA-lanreotide (DOTALAN) has a lower affinity for receptor 2 and a higher affinity for receptor 5 compared to DOTA-octreotide (DOTATOC).
The recorded history of music in Portugal dates back to the 6th century. The earliest documentation of a church singer in Portugal is from the year 525 and refers to an individual named André. Portuguese music initially consisted mostly of liturgical music and troubadourism. Over time, new folk traditions together with the influence of foreign cultures and the creation of new instruments, especially guitars, led to a diverse variety of regional folk music such as the fado, the Coimbra fado, and Madeira's folk music. Popular music in Portugal after the Carnation Revolution has been heavily influenced by American trends, which has led into the evolution of hip-hop tuga and popularisation of rock. Historically, Portugal has been a country of emigration which has heavily influenced the pimba in the 20th century and led to the introduction of Portuguese music into other cultures such as the ukelele in Hawaii in the 19th century.
Fourteen distinct types are available in addition to botanical tulips, including Lily-flowered, Fringed, Viridiflora, and Rembrandt. In addition to blooming season, tulip varieties differ in shape and height, and exhibit a wide range of colours, both pure and in combination.
==== Myotubular myopathy ==== Myotubular myopathy, also known as centronuclear myopathy, is recognized by pain during exercise and difficulty walking. People affected by this disease typically are wheelchair-reliant by middle adulthood, have weakness in the muscles involved in eye movement, nerve function disorders, and some form of intellectual disability. Myotubular myopathy is very rare, with less than 50 families currently affected. Genetically, myotubular myopathy can have two causes: autosomal dominant and autosomal recessive. When caused by a mutation in the DNM2 gene, the disorder is autosomal dominant, meaning it can be passed on by one mutated gene. When the mutation takes place in the BIN1 gene, the disease is instead autosomal recessive, and both genes must be mutated for the disease to be inherited. Autosomal recessive onset is most common.
Sources: en.wikipedia.org
=== Cardiac === In dermatomyositis, patients can develop myocarditis and cardiac conduction system abnormalities which may be detected if the patient undergoes special testing. However, these abnormalities typically have no symptoms or clinical consequences. More rarely, these abnormalities can cause greater issues and lead to arrhythmias, heart failure, or damage to heart valves. For those dermatomyositis patients who do have cardiac symptoms caused by the disease, their clinical course may be much worse than usual.
The minus sign comes from the convention that the force is considered towards the surface element, while the normal vector points outward. The equation has meaning in that, for any surface S in contact with the fluid, the total force exerted by the fluid on that surface is the surface integral over S of the right-hand side of the above equation. It is incorrect (although rather usual) to say "the pressure is directed in such or such direction". The pressure, as a scalar, has no direction. The force given by the previous relationship to the quantity has a direction, but the pressure does not. If we change the orientation of the surface element, the direction of the normal force changes accordingly, but the pressure remains the same. Pressure is distributed to solid boundaries or across arbitrary sections of fluid normal to these boundaries or sections at every point. It is a fundamental parameter in thermodynamics, and it is conjugate to volume. It is defined as a derivative of the internal energy of a system:
office Chris Iijima (1969), legal scholar, folksinger Andrei Markovits (1969), professor of comparative politics at the University of Michigan Michel Rosenfeld (1969), constitutional law scholar Mark Rosenzweig (1969), professor of economics at Yale University Steven M. Cohen (1970), sociologist, director of Berman Jewish Policy Archive at NYU's Robert F. Wagner Graduate School of Public Service Sheldon Danziger (1970), political scientist at the University of Michigan Lennard J. Davis (1970), professor of English at the University of Illinois at Chicago, specialist in disability studies John D'Emilio (1970), professor of history and gender studies at the University of Illinois at Chicago; winner of the Bill Whitehead Award in 2013 Samuel Estreicher (1970), professor at the New York University School of Law Peter Grossman (1970), professor of economics at Butler University; columnist, The Indianapolis Star Robert A. Leonard (1970), forensic linguist at Hofstra University and former member of rock band Sha Na Na Michael P. Mezzatesta (1970), art historian, director of the Nasher Museum of Art 1987–2003 Paul Starr (1970), sociologist; co-founder of The American Prospect and winner of the 1984 Pulitzer Prize for General Nonfiction Paul Berman (1971), historian and social critic Philip Nord (1971), historian and professor at Princeton University Steven J.
The Red Book, formally titled Nomenclature of Inorganic Chemistry, is a collection of recommendations on inorganic chemical nomenclature. It is published at irregular intervals, with the latest full edition published in 2005, in both paper and electronic versions.
The use of N-hydroxyphthalimide as a catalyst in the oxidation of KA oil avoids the formation of the undesirable by-product ammonium sulfate which is produced by the conventional ε-caprolactam synthesis (Beckmann rearrangement of cyclohexanone oxime with sulfuric acid). Alkanes are converted into nitroalkanes in the presence of nitrogen dioxide.
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.