prohibited list raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2026-07-08 and is reviewed periodically as new material appears.
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 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.
Reversed-phase high-performance liquid chromatography is the routine method for purity assessment. Peptides absorb near 214 nm because of the peptide bond, and a gradient of acetonitrile in water separates the intact peptide from deletion sequences, oxidised products, and earlier-eluting fragments at neutral pH. Electrospray ionisation mass spectrometry provides an orthogonal check: the measured mass must agree with the theoretical value. Amino acid analysis and peptide mapping confirm structure but are used less often. Reference standards remain scarce because the peptide is not described in any pharmacopoeia.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Synthetic cyclic heptapeptide |
| Molecular mass | Approximately 1024 g/mol | Depends on counter-ion content |
| Appearance | White to off-white powder | Commonly supplied as a lyophilised solid |
| Solubility | Freely soluble in water | Also dissolves in common aqueous buffers |
| Typical storage | -20 degrees Celsius, desiccated | Protect from light and repeated freeze-thaw |
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.
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.
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.
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.
The Romanowsky stains is considered a polychrome staining effect and is based on a combination of eosin plus (chemically reduced eosin) and demethylated methylene blue (containing its oxidation products azure A and azure B). This stain develops varying colors for all cell structures (“Romanowsky-Giemsa effect) and thus was used in staining neutrophil polymorphs and cell nuclei. Common variants include Wright's stain, Jenner's stain, May-Grunwald stain, Leishman stain and Giemsa stain. All are used to examine blood or bone marrow samples. They are preferred over H&E for inspection of blood cells because different types of leukocytes (white blood cells) can be readily distinguished. All are also suited to examination of blood to detect blood-borne parasites such as malaria.
It remains relatively common in sub-Saharan Africa. Outbreaks have been seen in refugee camps. Thiamine deficiency has been described for thousands of years in Asia, and became more common in the late 1800s with the increased processing of rice.
=== Physiologic variation === Leptin levels vary exponentially, not linearly, with fat mass. Leptin levels in blood are higher between midnight and early morning, perhaps suppressing appetite during the night. The diurnal rhythm of blood leptin levels may be modified by meal-timing.
Since DisplayPort's introduction in 2006, it has gained popularity within the computer industry and is featured on many graphics cards, displays, and notebook computers. Dell was the first company to introduce a consumer product with a DisplayPort connector, the Dell UltraSharp 3008WFP, which was released in January 2008. Soon after, AMD and Nvidia released products to support the technology. AMD included support in the Radeon HD 3000 series of graphics cards, and Nvidia first introduced support in the GeForce 9 series starting with the GeForce 9600 GT.
A protein subunit is a polypeptide chain or protein molecule that assembles (or "coassembles") with other protein molecules to form a protein complex. Large assemblies of proteins such as viruses often use a small number of types of protein subunits as building blocks. A key step in creating a recombinant protein vaccine is the identification and isolation of a protein subunit from the pathogen which is likely to trigger a strong and effective immune response, without including the parts of the virus or bacterium that enable the pathogen to reproduce. Parts of the protein shell or capsid of a virus are often suitable. The goal is for the protein subunit to prime the immune system response by mimicking the appearance but not the action of the pathogen. Another protein-based approach involves self‐assembly of multiple protein subunits into a virus-like particle (VLP) or nanoparticle. The purpose of increasing the vaccine's surface similarity to a whole virus particle (but not its ability to spread) is to trigger a stronger immune response. Protein subunit vaccines are generally made through protein production, manipulating the gene expression of an organism so that it expresses large amounts of a recombinant gene. A variety of approaches can be used for development depending on the vaccine involved. Yeast, baculovirus, or mammalian cell cultures can be used to produce large amounts of proteins in vitro. Protein-based vaccines are being used for hepatitis B and for human papillomavirus (HPV).
Sources: en.wikipedia.org
A similar system achieves the same temporal control of condensate formation by using light-sensitive 'caged' dimerizers. In this case, light-activation removes the dimerizer cage, allowing it to recruit IDRs to multivalent cores, which then triggers phase separation. Light-activation of a different wavelength results in the dimerizer being cleaved, which then releases the IDRs from the core and consequentially dissolves the condensate. This dimerizer system requires significantly reduced amounts of laser light to operate, which is advantageous because high intensity light can be toxic to cells. Optogenetic systems can also be modified to gain spatial control over the formation of condensates. Multiple approaches have been developed to do so. In one approach, which localizes condensates to specific genomic regions, core proteins are fused to proteins such as TRF1 or catalytically dead Cas9, which bind specific genomic loci. When oligomerization is trigger by light activation, phase separation is preferentially induced on the specific genomic region which is recognized by fusion protein. Because condensates of the same composition can interact and fuse with each other, if they are tethered to specific regions of the genome, condensates can be used to alter the spatial organization of the genome, which can have effects on gene expression.
49 Squadron RAF in October 1956 in Operation Buffalo at Maralinga; Project Dazzle and its research on re-entry vehicles enabled the Mercury-Atlas 6 launch to happen in February 1962; the Australian government built four launch pads for the Blue Streak in 1959, but it was cancelled in 1960, the redesignated satellite launcher Blue Streak first launched on 5 June 1964, and satellites would be launched by 1966, but only WRESAT was launched in November 1967, on a Redstone rocket instead; Woomera launched over 4000 missiles and cost the Australian government £900m; the site was demolished by the Australian government at the end of the 1960s; part of the former site is now the secret Joint Defense Facility Nurrungar 17 September Not in the Stars, making mathematical models for predictions; Robert May, Baron May of Oxford of Imperial College; William Phillips and his 1949 MONIAC economic model; a British Airways 747 flight simulator; computer models of epidemics - the R number, and vaccination policies; the UK fishing industry had quotas imposed in 1983, due to mathematical models of fish stocks; John Shepherd of the Centre for Environment, Fisheries and Aquaculture Science (CEFAS) laboratory in Lowestoft; computer models of warfare were developed by the Defence Operational Analysis Establishment in West Byfleet with deputy director David Faddy, which closed six years later, superseded in function by CORDA (UK); Irving Mintzer of the World Resources Institute; the NASA Goddard Space Flight Center had developed computer models of the Earth's atmosphere, such as rainfall; the hole in the Ozone layer and phytoplankton, with Norman Myers; Ian Riley of the Economist Intelligence Unit. Narrated by Bob Peck. Written, produced and directed by Chris Haws, made by InCA 24 September Race for the Top, CERN versus Fermilab; in 1983 CERN discovered the W and Z bosons, it and Fermilab were looking for the top quark; Leon M. Lederman, director of Fermilab; Andy Parker of CERN; CERN had 80 scientists led by Luigi Di Lella on its UA2 experiment, and Fermilab had its Collider Detector at Fermilab (CDF); Roy Schwitters; Fermilab had discovered the bottom quark in 1977; John Ellis of CERN; each team prepared for an annual physics conference at La Thuile, Aosta Valley in north-west Italy; UA2 had a meeting in July 1989 in Cambridge; the top quark would be discovered in 1995 with 175 GeV by Fermilab. Narrated by Carole Boyd, known for playing Lynda Snell in The Archers, joint production InCA and WGBH 1 October Walk on Wheels, a half-million disabled people have a wheelchair in the UK; NHS wheelchairs were made by Carter's; the quick-release axle was developed in World War II, for releasing munitions; the residential Treloar School in Alton, Hampshire, which was funded by individual LEAs, with charity funding as well; Bill Walmsley of the Department of Health's wheelchair research centre in Blackpool, now part of the Disability and Carers Service at DWP Peel Park at the end of the M55 motorway, on the A5230 in Westby-with-Plumptons. Narrated by John Hedges, produced by Jeremy Llewellyn-Jones, made by Chrysalis Television (North One Television) 8 October Invasion of the Body Scanners, a reference to the 1956 film Invasion of the Body Snatchers; X-rays were introduced in the 1890s, but it took fifty years to vastly improve the early crude techniques; CT was invented in the late 1960s - its inventor with Prince Philip, Duke of Edinburgh; Ian McDougall at a magnet technology company, who designed the first magnet, cooled with liquid helium in 1979; X-ray scans were a fairly crude process, but other types required computer image processing; Michael Boswell of GE Medical Systems; scans were taken in the coronal plane and sagittal plane; by 1989 the NHS only had four of these scanners - one was at Frenchay Hospital, made by GEC Medical (Picker International) - there were around 25 scanners in the whole UK; the Brockton Hospital; there were 1500 scanners in the US, with 39 in Massachusetts; Donald Longmore of the National Heart and Chest Hospitals, who performed the UK's first heart transplant on 3 May 1968; CT scanning had been performed for neuroradiology since the mid-1970s; radiology at Middlesex Hospital; medical ultrasound was a much safer technique than X-rays, and a new type deployed the Doppler effect, but medical ultrasound lacked cast-iron image definition; but scanners were hideously expensive, due to the convoluted enormous magnets that were required. Narrated by John Benson, produced by Mike Johnstone, directed by Ed Newstead, made by VATV (Video Arts) 15 October Wheels of War, about the early 1990s Leyland 4-tonne truck and defence procurement; James Adams, journalist; military historian Correlli Barnett; general service (GS) cargo vehicles, and a RE vehicle carrying a Medium Girder Bridge; a youthful-looking Mark Francois; the Austin Champ, designed in the 1950s; the British Aerospace Nimrod AEW3 was cancelled in 1986 at a cost of £860m; cost-plus contracts were replaced by competitive; Sir Peter Levine was brought in as Chief of Defence Procurement; the Leyland 4-tonne truck would replace the Bedford MK, made by Bedford Vehicles; journalist John Parsons; each vehicle would cost around £23,000 each; the Leyland 5-tonne was developed from its Comet and Roadrunner vehicles (developed into the DAF LF) under project director Stuart Hayes; the equivalent German vehicle, the MAN KAT1, had cost £75,000 each; the Panavia Tornado; Leyland design engineer Colin Ingram; the three vehicle prototypes were punishingly tested at the Royal Armament Research and Development Establishment (RARDE). Narrated by Anthony Valentine, produced by Patrick Uden made by Uden Associates 22 October Three Score Years and Then? 29 October Robotopia, advances of robotics in Japan, and bizarre contraptions; Frederik L. Schodt, author of the 1988 book Inside the Robot Kingdom - for hundreds of years until 1853, Japan was a fairly backward country; Joseph Engelberger, who developed the first industrial robot, Unimate, made by his company Unimation from 1961 - there were around 200,000 industrial robots, with around 130,000 of those in Japan; Japanese robot artist Hajime Sorayama, who drew lurid female robots; automated mannequins; nineteen universities in Japan were developing ungainly humanoid robots, notably Ichiro Kato at Waseda University; Seiuemon Inaba of FANUC, produced by Mike Wallington, made by Kai Productions 5 November Fly-by-wire, the new Airbus 320; software engineer Mike Hennell of the University of Liverpool; Roger Beteille, managing director of Airbus from 1967–85, and Henri Ziegler; John Knight of the University of Virginia; software engineer Bev Littlewood of City University; the A320 was the first fly-by-wire airliner; Blind Landing Experimental Unit testing at RAE Bedford in the 1960s, and developing the automatic pilot with a Vickers Valetta; testing Concorde in a wind tunnel; the Apollo project had depended on computers - it couldn't be done otherwise; Paul Ceruzzi of the Air and Space Museum; Philip Felleman of the Draper Laboratory; testing the F-16 in the early 1970s; Joe Sutter, head of Boeing from 1981–86; Boeing introduced flight management systems, so not needing a flight engineer; David Learmount of Flight International, and how Airbus had more commercial need to be innovative; the A300 was the first two-engined wide body aircraft; the A310 had electrical hydraulics and electronic control of some flight surfaces; John Cullyer of the University of Warwick; the A320 had five master computers; Gordon Corps, the Airbus test pilot, later to fly on Thai Airways International Flight 311 in 1992; Gilles Pichon, chief engineer of the A320; Jacques Troyes, head of Flight Control at Airbus; there was emergency mechanical control to the rudder and tail trim; the June 1988 Air France Flight 296Q - Michel Asseline, the pilot, said the aircraft had tried to land, when he tried to raise the aircraft; Alain Monnier of the DGAC said it was pilot error; Greg Holt of the FAA and Brian Perry of the CAA; the four-engined A330 would be manufactured from 1992; a prototype fly-by-wire relaxed stability Saab JAS 39 Gripen tumbles on 2 February 1989 at Linköping/Saab Airport, piloted by Lars Rådeström. Narrated by James Bellini, produced by Ben Shephard (historian), directed by John Longley, made by Box Television with WGBH 12 November Deadly Force, aerial shots of Miami; the WINZ Miami broadcaster; the Miami SWAT response team; the 1980 Miami riots; Sgt Louis Battle, Bernie Gonzalez and the Heckler & Koch MP5; Tom Salerno and the Remington Model 870 pump action shotgun, the M1911 pistol and Beretta M9; Ted Bradley; a WSVN news broadcast with Jane Akre; two thirds of Miami's population were Latin-American, and had many exiled citizens; the 1980 Mariel boatlift, from Cuba, added to the population and much to the crime; Miami had two murders a day in the 1980s; Robert Waller; Edna Buchanan of the Miami Herald; severed limbs washed up on Miami beach; the Colt Python; the Beretta 92; the Colt AR-15 semi-automatic rifle; 80% of SWAT call-outs were connected to the drug trade; two thirds of illegal drugs went through Miami; Sgt Louis Philips and negotiation techniques; SWAT negotiator Eric Caspener; 95% of SWAT negotiations work. Produced by David Jones, directed by Catherine Bailey, made by Buffalo Pictures 19 November Faster than a Speeding Bullet, and the quest for supersonic flight, eventually resulting in Concorde. The programme features former Concorde pilot Christopher Orlebar, who wrote The Concorde Story. The history of supersonic research dates back to the 18th Century, but supersonic flight only became achievable after the development of the jet engine. Featured aircraft include: the wartime Messerschmitt Me 262; the innovative de Havilland DH 108; the Messerschmitt Me 163 Komet; the Fairey Delta 2, the Bell X1 and numerous experimental "X Planes". After the war, the world's fastest non-experimental aircraft was the Lockheed SR-71 Blackbird, which could fly at 95,000 ft at 2,300 mph. The programme interviews key figures in the development of supersonic military aircraft and second generation SST (Supersonic Transport) aircraft. Narrated by Tony Anholt, written, produced and directed by Chris Haws, made by InCA
Chem. Int. Ed. 2017, 56, 16018-16022. https://doi.org/10.1002/anie.201709463. M, Hifsudheen.; R, K, Mishra.; B, Vedhanarayanan.; V, K, Praveen.; and Ajayaghosh, Ayyappanpillai (2017). “Helix to Super-Helix Transition in p-Systems Self-assembly: Superseding of Molecular Chirality at Hierarchical Level”. Angew. Chem., Int. Ed. 2017, 56, 12634-12638. https://doi.org/10.1002/anie.201707392. S, Ghosh.; S, Cherumukkil.; C, H, Suresh.; and Ajayaghosh, Ayyappanpillai (2017). “A Supramolecular Nanocomposite as Near Infrared Transmitting Optical Filter for Security and Forensic Applications”. Adv. Mater. 2017, 29, 1703783.doi:10.1002/adma.201703783 A, Mal.; R, K, Mishra.; V, K, Praveen.; M, A, Khayum.; R, Banerjee.; and Ajayaghosh, Ayyappanpillai (2018). “Supramolecular Reassembly of Self-Exfoliated Ionic Covalent Organic Nanosheets for Label-Free Detection of dsDNA”. Angew. Chem., Int. Ed. 2018, 57, 8443. https://doi.org/10.1002/anie.201801352. R, D, Mukhopadhyay.; G, Das.; and Ajayaghosh, Ayyappanpillai (2018). “Stepwise Control of Host-Guest Interaction Using a Coordination Polymer Gel”. Nat. Commun. 2018, 9, 1987. https://doi.org/10.1038/s41467-018-04303-8. V, K, Praveen.; B, Vedhanarayanan.; A, Mal.; R, K, Mishra.; and Ajayaghosh Ayyappanpillai (2020). “Self-Assembled Extended p‑Systems for Sensing and Security Applications”. Acc. Chem. Res. 2020, 53, 2, 496-507. https://doi.org/10.1021/acs.accounts.9b00580 S, Chakraborty.; M, M, Joseph.; S, Varughese.; S, Ghosh.; K, K, Maiti.; A, Samanta.; and Ajayaghosh, Ayyappanpillai (2020).
== Use and effects == Salvinorin A is active at doses as low as 200 μg. It has only been administered to humans in a few studies, one showing that its effects peaked at about 2 minutes, that its subjective effects may overlap with those of serotonergic psychedelics, and that it temporarily impairs recall and recognition memory. Like most other agonists of KOR, salvinorin A produces sedation, psychotomimesis, dysphoria, anhedonia, and depression.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide and an analogue of alpha-melanocyte-stimulating hormone. The molecule is produced by chemical synthesis rather than extracted from a biological source.
It is shorter than the native hormone and carries a cyclic constraint that improves stability. These changes raise receptor potency and slow breakdown relative to the naturally occurring peptide.
Published accounts date its development to the 1980s, when researchers were generating analogues of melanocyte-stimulating hormone. That work aimed to produce more stable compounds for studying pigmentation biology.
Low temperature slows hydrolysis and oxidation, the two main routes by which the peptide backbone and side chains are modified. A lyophilised powder stored at −20 °C is more stable than one kept at room temperature, and once the material is dissolved the degradation rate rises, making refrigeration more important.