The short version of reversed-phase HPLC fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-11-29. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
| 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 |
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.
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.
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.
== G == Gabriel ethylenimine method Gabriel synthesis Gabriel–Colman rearrangement, Gabriel isoquinoline synthesis Gallagher–Hollander degradation Gassman indole synthesis Gastaldi synthesis Gattermann aldehyde synthesis Gattermann Koch reaction Gattermann reaction Geminal halide hydrolysis Gewald reaction Gibbs phthalic anhydride process Gilman reagent Glaser coupling Glycol cleavage Goldberg reaction Gomberg–Bachmann reaction Gomberg–Bachmann–Hey reaction Gomberg radical reaction Gould–Jacobs reaction Graebe–Ullmann synthesis Grignard degradation Griesbaum coozonolysis Grignard reaction Grob fragmentation Grubbs' catalyst in Olefin metathesis Grundmann aldehyde synthesis Gryszkiewicz–Trochimowski and McCombie method Guareschi–Thorpe condensation Guerbet reaction Gutknecht pyrazine synthesis
== Research == G protein-biased MOR agonists like SR-17018 have potential medical applications as analgesics in the treatment of pain and as opioid substitutes in the treatment of opioid dependence and withdrawal. However, it remains unclear whether G protein-biased MOR agonists, such as SR-17018 and oliceridine, are truly clinically advantageous to conventional MOR agonists. SR-17018 has only been assessed in preclinical research and has not been formally studied in humans. Improved analogues of SR-17018 are being studied by Laura Bohn and colleagues as of December 2025.
The peaceful transition of power from Cardoso to his main opposition leader, Luiz Inácio Lula da Silva (elected in 2002 and re-elected in 2006), was seen as proof that Brazil had achieved a long-sought political stability. However, sparked by discontent accumulated over decades from corruption, police brutality, inefficiencies of the political establishment and public service, numerous peaceful protests erupted in Brazil in the middle of the first term of Dilma Rousseff, who had succeeded Lula after winning election in 2010 and again in 2014 by narrow margins. Rousseff was impeached by the Brazilian Congress in 2016, halfway into her second term, and replaced by her vice-president Michel Temer, who assumed full presidential powers after Rousseff's impeachment was accepted on 31 August. Large street protests for and against her took place during the impeachment process. The charges against her were fueled by political and economic crises along with evidence of involvement with politicians from all the primary political parties. In 2017, the Supreme Court requested the investigation of 71 Brazilian lawmakers and nine ministers of President Michel Temer's cabinet who were allegedly linked to the Petrobras corruption scandal. President Temer himself was also accused of corruption. In the fiercely contested 2018 elections, the controversial conservative candidate Jair Bolsonaro of the Social Liberal Party (PSL) was elected president, winning in the second round against Fernando Haddad, of the Workers Party (PT), with the support of 55.13% of the valid votes.
== Allegations and events leading up to the arrests == In the spring of 2022, Belgian security services mounted a surveillance operation against former MEP Antonio Panzeri, following a tip-off from another European intelligence service that he had been accepting bribes from Morocco. Information was passed on to the federal prosecutor's office, which opened an investigation in July 2022. According to the testimony of Francesco Giorgi, since 2019, Qatar has funneled cash to Antonio Panzeri. Panzeri, a former member of the European Parliament, and Eva Kaili, a sitting member, were trying to influence voting at the European Parliament in favour of Qatar. Bribes related to Qatar, as well as the Mauritanian government, were, according to Giorgi, channeled through a Brussels-based organization co-founded by Panzeri called Fight Impunity. Iqbal Survé, a controversial businessman from South Africa, was found to be the largest donor to Fight Impunity via his Sekunjalo Development Foundation. Survé's foundation made a donation of €250,000 to the lobbying group between July and September 2020. Belgian authorities are investigating a broader scheme, aimed at influencing decisions by the European Parliament in favour of Qatar. Panzeri's testimony contradicts that of Giorgi, who is Kaili's partner and a former parliamentary advisor to Panzeri, in certain aspects. In his leaked interview with Belgian authorities, Panzeri claimed that the first cash payments came from Morocco, prior to Qatar's involvement.
== Derivative terms and sundry usages == Derivative terms include various adjectival forms such as integumentary (e.g. system), integumental (e.g. integumental glands, "peltate glands, the integument being raised like a bladder due to abundant secretion") and integumented (as opposed to bare). Other illustrative examples of usage occur in the following articles:
Sources: en.wikipedia.org
The common death adder (Acanthophis antarcticus) is a highly venomous snake species with a 50–60% untreated mortality rate. It is also the fastest striking venomous snake in the world. A death adder can go from a strike position, to strike and envenoming their prey, and back to strike position again, in less than 0.15 seconds. The SC LD50 value is 0.4 mg/kg and the venom yield per bite can range anywhere from 70–236 mg. Unlike other snakes that flee from approaching humans crashing through the undergrowth, common death adders are more likely to sit tight and risk being stepped on, making them more dangerous to the unwary bushwalker. They are said to be reluctant to bite unless actually touched.
Major Force reappears in Battle for Blüdhaven, a series set a year after the events of Infinite Crisis, as the leader of project S.H.A.D.E. In issue #5, Major Force brutally beats Outsiders member Major Victory and rips off his right arm. He also picks a fight with Hal Jordan, having vowed to kill Green Lanterns on sight after his last encounter with Kyle Rayner. Captain Atom drains Major Force of his energy, leaving him a deflated husk. Major Force is later seen reconstituted and a part of a new regiment of S.H.A.D.E. soldiers. A battle ensues with Uncle Sam and the Freedom Fighters for the soul of America, wherein Major Force is quickly dispatched by Miss America. Major Force later appears as a member of the Secret Society during the wedding of Green Arrow and Black Canary.
Apitoxin or bee venom is the venom produced by the honey bee. It is a cytotoxic and hemotoxic bitter colorless liquid containing proteins, which may produce local inflammation. It may have similarities to sea nettle toxin.
=== Geographical distribution of government === In West Germany, most of the political agencies and buildings were located in Bonn, while the German Stock Market was located in Frankfurt which became the economic center. The judicial branch of both the German Federal Constitutional Court (Bundesverfassungsgericht) and the highest Court of Appeals, were located in Karlsruhe. The West German government was known to be much more decentralised than its state socialist East German counterpart, the former being a federal state and the latter a unitary one. Whilst East Germany was divided into 15 administrative districts (Bezirke), which were merely local branches of the national government, West Germany was divided into states (Länder) with independently elected state parliaments and control of the Bundesrat, the second legislative chamber of the Federal Government.
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.
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.