cyclic heptapeptide is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-04-23. Where a claim depends on a specific study, the study is described rather than over-claimed.
Scientific discussion of Melanotan-2 spans pharmacology, dermatology, and public-health literature. Laboratory studies examine its receptor binding and cellular effects, while clinical reports describe outcomes observed after unregulated use. These two bodies of work differ in rigour and intent. Peer-reviewed trials of the compound as a medicine are limited, so much of the available information comes from case reports and surveillance data. Authors frequently note the gap between experimental findings and real-world use.
Reported observations after unregulated use include shifts in skin pigmentation and, in some accounts, unintended changes to moles and other lesions. Whether these outcomes are causally linked to the compound, and how often they occur, remain open questions because controlled data are scarce. The absence of standardised dosing and verified product purity complicates interpretation. Researchers have called for better surveillance and analytical characterisation of samples obtained outside regulated channels. Conclusions drawn from anecdotal evidence should be treated as provisional.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Regulatory status | Unapproved for therapeutic use | No marketing authorisation from major agencies |
| Legal classification | Varies by jurisdiction | Prescription-only or controlled in several countries |
| Common synonyms | Melanotan II; MT-II | Also referenced by catalogue codes |
| Typical analytical method | Reverse-phase HPLC | Often paired with mass spectrometry |
| Primary literature focus | Receptor pharmacology | Pigmentation and melanocortin signalling |
Solid peptide kept dry at minus twenty degrees Celsius, shielded from light and moisture, is generally considered stable for extended periods. Solutions are divided into single-use aliquots and held at minus twenty or minus eighty degrees Celsius, because repeated freeze-thaw cycles promote aggregation and loss of material to container surfaces. Hydrolysis of the backbone and oxidation of tryptophan are the principal degradation routes in aqueous solution, and both accelerate at ambient temperature. Hygroscopic uptake after a vial is opened can also shift the actual mass weighed, which affects any concentration calculated from it.
Routine characterisation relies on reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, using a C18 column and a water-acetonitrile gradient containing trifluoroacetic acid. Electrospray ionisation mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidised by-products that co-elute poorly. Sequence and stereochemistry require additional work, such as peptide mapping or amino acid analysis, because a chromatographic purity figure alone does not distinguish a diastereomer from the target peptide. Independent testing of research-grade material frequently shows measured content below the stated label, so a certificate of analysis is best read together with the method that produced it.
Melanotan-2 is handled in the laboratory as a lyophilised powder that dissolves readily in water, dimethyl sulfoxide and dimethylformamide, with limited solubility in ethanol. Stock solutions prepared in an organic solvent often precipitate when diluted into aqueous buffer, so gradual dilution with mixing is standard practice. The peptide carries a tryptophan residue and a histidine residue, both sensitive to oxidation and to alkaline conditions. Working solutions are therefore kept near neutral to slightly acidic pH, protected from light, and consumed within the same working session whenever that is practical.
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.
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.
Due to the rules, his case could have led to disqualification from the Seoul Olympics and suspension from competition for six months. The levels of the combined stimulants registered in the separate tests were 2 ppm, 4 ppm and 6 ppm. Lewis defended himself, claiming that he had accidentally consumed the banned substances. After the supplements that he had taken were analyzed to prove his claims, the USOC accepted his claim of inadvertent use, since a dietary supplement he ingested was found to contain "Ma huang", the Chinese name for Ephedra (ephedrine is known to help weight-loss). Fellow Santa Monica Track Club teammates Joe DeLoach and Floyd Heard were also found to have the same banned stimulants in their systems, and were cleared to compete for the same reason. The highest level of the stimulants Lewis recorded was 6 ppm, which was regarded as a positive test in 1988 but is now regarded as negative test. The acceptable level has been raised to ten parts per million for ephedrine and twenty-five parts per million for other substances. According to the IOC rules at the time, positive tests with levels lower than 10 ppm were cause of further investigation but not immediate ban.
=== Risk in adding too much === Nitrogen supplements, particularly DAP, stimulates yeast reproduction and can greatly increase the biomass. This could have the consequence of speeding up the fermentation rate faster than what a winemaker may desire and will also increase the fermentation temperature due to the heat being generated by the yeast. The excess biomass can also create a scarcity of other yeast nutrients, such a vitamins and sterols, due to increase competition and may lead to the production of off-odors (such as hydrogen sulfide) and even stuck fermentations. Excessive levels of the amino acid arginine (greater than 400 mg/L), especially near the end of fermentation, can pose the risk increase the production of ethyl carbamate. This is because arginine gets broken down into urea which can be reabsorbed and utilized by yeast or metabolized into ammonia. However, urea also reacts with ethanol if it is not completely metabolized which coupled with long term exposure (as well as high temperatures) can lead to the production of the ester ethyl carbamate.
The influence of Nasser's Arab nationalism over the RCC was immediately apparent. The administration was instantly recognized by the neighbouring Arab nationalist regimes in Egypt, Syria, Iraq, and Sudan, with Egypt sending experts to aid the inexperienced RCC. Gaddafi propounded pan-Arab ideas, proclaiming the need for a single Arab state stretching across North Africa and the Middle East. In December 1969, Libya signed the Tripoli Charter alongside Egypt and Sudan. This established the Arab Revolutionary Front, a pan-national union designed as a first step towards the eventual political unification of the three nations. In 1970 Syria declared its intention to join. Nasser died unexpectedly in September 1970, with Gaddafi playing a prominent role at his funeral. Nasser was succeeded by Anwar Sadat, who replaced the idea of a unified state with a political federation, implemented in April 1971; in doing so, Egypt, Syria, and Sudan received large grants of Libyan oil money. In July 1971, Gaddafi sided with Sadat against the Soviet Union in the 1971 Sudanese coup d'état and dispatched Libyan fighter jets to force down a British Overseas Airways Corporation jetliner carrying the leading coup plotters, Farouk Osman Hamadallah and Babikir al-Nour. They were extradited back to Khartoum, where they were promptly executed by Sudanese leader Jaafar Nimeiry. In February 1972, Gaddafi and Sadat signed an unofficial charter of merger, but it was never implemented because relations broke down the next year.
Sources: en.wikipedia.org
The March of the Chinese People's Liberation Army was adopted as the military anthem by the Central Military Commission on 25 July 1988. The lyrics of the anthem were written by composer Gong Mu (real name: Zhang Yongnian; Chinese: 张永年) and the music was composed by Korea-born Chinese composer Zheng Lücheng.
== Biological function and classification == In eukaryotes, glutathione S-transferases (GSTs) participate in the detoxification of reactive electrophilic compounds by catalysing their conjugation to glutathione. The GST domain is also found in S-crystallins from squid, and proteins with no known GST activity, such as eukaryotic elongation factors 1-gamma and the HSP26 family of stress-related proteins, which include auxin-regulated proteins in plants and stringent starvation proteins in Escherichia coli. The major lens polypeptide of cephalopods is also a GST. Bacterial GSTs of known function often have a specific, growth-supporting role in biodegradative metabolism: epoxide ring opening and tetrachlorohydroquinone reductive dehalogenation are two examples of the reactions catalysed by these bacterial GSTs. Some regulatory proteins, like the stringent starvation proteins, also belong to the GST family. GST seems to be absent from Archaea in which gamma-glutamylcysteine substitute to glutathione as major thiol.
In the 1970s, antineoplastic (chemotherapy) drugs were identified as hazardous, and the American Society of Health-System Pharmacists (ASHP) has since then introduced the concept of hazardous drugs after publishing a recommendation in 1983 regarding handling hazardous drugs. The adaptation of federal regulations came when the U.S. Occupational Safety and Health Administration (OSHA) first released its guidelines in 1986 and then updated them in 1996, 1999, and, most recently, 2006. The National Institute for Occupational Safety and Health (NIOSH) has been conducting an assessment in the workplace since then regarding these drugs. Occupational exposure to antineoplastic drugs has been linked to multiple health effects, including infertility and possible carcinogenic effects. A few cases have been reported by the NIOSH alert report, such as one in which a female pharmacist was diagnosed with papillary transitional cell carcinoma. Twelve years before the pharmacist was diagnosed with the condition, she had worked for 20 months in a hospital where she was responsible for preparing multiple antineoplastic drugs. The pharmacist did not have any other risk factor for cancer, and therefore, her cancer was attributed to the exposure to the antineoplastic drugs, although a cause-and-effect relationship has not been established in the literature. Another case happened when a malfunction in biosafety cabinetry is believed to have exposed nursing personnel to antineoplastic drugs. Investigations revealed evidence of genotoxic biomarkers two and nine months after that exposure.
== External links == Pathway at biocarta.com Nosek, Thomas M. "Section 6/6ch2/s6ch2_34". Essentials of Human Physiology. Archived from the original on 2016-03-24. Overview of all the structural information available in the PDB for UniProt: P01282 (VIP peptides) at the PDBe-KB.
Sources: en.wikipedia.org
However, Smithwick et al.'s study noted that, after further preparation, this irregular surface was simply a layer of sediment with a different color than the rest of the slab. The 'frill' or 'halo' of collagen identified by Feduccia was also determined to be misidentified sediment surrounding one of the specimens. Smithwick et al.'s study concluded by stating that the integument preserved on Sinosauropteryx closely resembled that of birds preserved in the same formation. Purported features of collagen fibers were in fact misidentified shadows formed by scratches or irregular sediment, a misidentification perpetuated by the low quality of early Sinosauropteryx photographs.
=== Compilation albums === Mrs. Dolphin (10 January 1991), Japanese release containing Barging Into the Presence of God and the Half-Life EPs with the tracks "Colours and Shapes" and "A Deeper Sleep for Steven"
== Mechanism of action == Interferon beta balances the expression of pro- and anti-inflammatory agents in the brain, and reduces the number of inflammatory cells that cross the blood brain barrier. Overall, therapy with interferon beta leads to a reduction of neuron inflammation. Moreover, it is also thought to increase the production of nerve growth factor and consequently improve neuronal survival. In vitro, interferon beta reduces production of Th17 cells which are a subset of T lymphocytes believed to have a role in the pathophysiology of MS.
Sources: en.wikipedia.org
Major regulatory agencies have not approved it for any indication. Some countries permit it only under prescription frameworks, while others classify it as a controlled substance.
Much of the evidence comes from case reports and accounts of unregulated use rather than controlled trials. Differences in product purity and dosing add further variability.
Laboratory work focuses on receptor binding and cellular signalling. Observational reports document outcomes after use, and analytical chemists examine samples to assess content and purity.
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.