afamelanotide comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Updated 2025-08-21. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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.
Outside regulated medicine, melanotan II circulates through online vendors as a research chemical, often marketed for tanning. Products sold this way vary widely in purity, concentration, and labeling accuracy, and independent testing has documented discrepancies. Published reports describe both pigment effects and adverse reactions, including nausea, flushing, and darkening of existing moles. Long-term safety data are sparse, and no large controlled trial has established a risk profile. Questions about cumulative effects on melanocytes remain unresolved in the literature.
Melanotan II is a synthetic peptide analog modeled on alpha-melanocyte-stimulating hormone, a naturally occurring signaling peptide involved in pigmentation. Its structure is a cyclic heptapeptide containing two non-natural substitutions, norleucine at position four and D-phenylalanine at position seven. These modifications resist enzymatic breakdown and extend the molecule's activity relative to the native hormone. The compound binds melanocortin receptors and is studied mainly as a pharmacological tool rather than a therapeutic product. It has never received approval as a medicine in any major jurisdiction.
| 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 compound emerged from research programs in the 1980s that examined analogues of alpha-melanocyte-stimulating hormone for pigmentation and photoprotection. Investigators modified the native sequence to extend activity duration and potency. A related analogue, afamelanotide, was developed within the same broad line of inquiry and eventually gained approval in certain jurisdictions for a rare light-sensitivity condition. Melanotan-2 itself did not progress through the same regulatory route and has no approved therapeutic indication.
Melanocortin receptors comprise five subtypes with distinct tissue distributions and functions. Melanotan-2 is described in the literature as a non-selective agonist that engages several of these subtypes, including MC1R, MC3R, MC4R, and MC5R. MC1R is the subtype most directly linked to melanin production in skin cells. Because the compound is not subtype-selective, its observed effects in experimental settings are generally attributed to activity across multiple receptor pathways rather than to a single target.
Melanotan-2 is a synthetic linear peptide built from seven amino acids arranged in a short chain. Its sequence is commonly written as Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-NH2, which includes a modified N-terminus and an amidated C-terminus. The molecule belongs to the melanocortin family and acts as a receptor agonist. Structural features such as the D-phenylalanine residue and the Nle substitution are associated with increased stability against enzymatic degradation relative to the natural parent peptide.
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.
=== Hair growth === Dermal macrophages are the essential component of the hair follicle immune system. They generally facilitate hair growth. There are three steps of hair growth: anagen, catagen, and telogen. During catagen, dermal macrophages' population decreases progressively when the hair grows. The number of dermal macrophages in hair follicles reaches a minimum during telogen (resting state) and increases during anagen (beginning of another growth cycle). In rodents, perifollicular macrophages can actively remove collagen fibres around the follicles via phagocytosis. This phenomenon might contribute to remodelling the follicular composition during anagen when dermal macrophages prevent the activation of follicular stem cells, thereby preventing entry to catagen, a process in which hair stops growing. Hence, dermal macrophages facilitate the growth of the hair by preventing the halt of the growth process and its regression. When under physical stress, the release of CCL2 (cytokine) in the hair follicle induces the infiltration of macrophages. The infiltrated macrophages mainly express an M1 phenotype, which are pro-inflammatory macrophages that could trigger apoptosis of cells in the follicle by their upregulation of pro-inflammatory cytokines such as TNF-a. However, TNF-a is a major factor facilitating hair regeneration by promoting various pathways' signalling (Wnt, NF-κB pathway). Dermal macrophages could also contribute to hair regeneration by skewing towards the anti-inflammatory phenotype (M2) under minor stress.
== Reasons for validation == FDA, or any other food and drugs regulatory agency around the globe not only ask for a product that meets its specification but also require a process, procedures, intermediate stages of inspections, and testing adopted during manufacturing are designed such that when they are adopted they produce consistently similar, reproducible, desired results which meet the quality standard of product being manufactured and complies the Regulatory and Security Aspects. Such procedures are developed through the process of validation. This is to maintain and assure a higher degree of quality of food and drug products. "Process validation is defined as the collection and evaluation of data, from the process design stage through commercial production, which establishes scientific evidence that a process is capable of consistently delivering quality product. Process validation involves a series of activities taking place over the lifecycle of the product and process.". A properly designed system will provide a high degree of assurance that every step, process, and change has been properly evaluated before its implementation. Testing a sample of a final product is not considered sufficient evidence that every product within a batch meets the required specification.
=== Enzyme coagulants === Among enzymes that have been shown to produce tofu are papain, and alkaline and neutral proteases from microorganisms. Papain, moreover, has been studied as a gelling agent to produce "instant tofu" from soy protein isolate and soy glycinin (11S) protein. Contemporary tofu manufacturers may choose to use one or more of these coagulants since each plays a role in producing the desired texture in the finished tofu. Different textures result from different pore sizes and other microscopic features in the tofu produced using each coagulant. The coagulant mixture is dissolved in water, and the solution is then stirred into boiled soy milk until the mixture curdles into a soft gel. Coagulants are typically added at concentrations between 1.5 and 5.0 g/kg. In all coagulants consisting of calcium or magnesium salts, the positive double-bonded ions of the calcium or magnesium are responsible for the coagulation of the soy proteins which become part of the tofu, thereby enhancing its nutritional value. Only 1 part per 1000 of the tofu eaten is coagulant; most of the coagulant reacts with soy protein and is broken down into ions. The non-reactive portion dissolves in the soy whey and is discarded. Although tartness is sometimes desired in dessert tofu, the acid used in flavoring is usually not the primary coagulant, since concentrations sufficiently high to induce coagulation negatively affect the flavor or texture of the resulting tofu.
== Sources == Bath, Richard (ed.) The Complete Book of Rugby (Seven Oaks Ltd, 1997 ISBN 978-1-86200-013-1) ed. Brown, Archie; Kaser, Michael & Smith, Gerald S. (ed.s) The Cambridge Encyclopedia of Russia and the former Soviet Union, (2nd Ed., Cambridge University Press, Cambridge, England 1994; ISBN 0-521-35593-1) Cotton, Fran (Ed.) The Book of Rugby Disasters & Bizarre Records. (Compiled by Chris Rhys, Century Publishing, London, 1984). ISBN 0-7126-0911-3 Griffiths, John. Rugby's Strangest Matches: Extraordinary but true stories from over a century of rugby (Past Times/Robson Books, England; ISBN 978-1-86105-354-1) Hopkins, John (ed) Rugby (1979 ISBN 0-304-30299-6) Laidlaw, Chris From Twickers with Love: Rugby's Universal Message in Hopkins, John (ed) Rugby (1979 ISBN 0-304-30299-6) Richards, Huw A Game for Hooligans: The History of Rugby Union (Mainstream Publishing, Edinburgh, 2007, ISBN 978-1-84596-255-5) Riordan, James Sport in Soviet Society — development of sport and physical education in Russia and the USSR (Cambridge University Press, Cambridge, England, 1977) Sorokin, A.A. (А. А.
=== Video === Closed circuit video is also popular, as this allows the surface personnel to see what the diver is doing, which is particularly useful for inspection work, as a non-diving specialist can see the underwater equipment in real time and direct the diver to look at particular features of interest.
Sources: en.wikipedia.org
== History == Photoionization has a long history of use in mass spectrometry experiments, though mostly for research purposes and not for sensitive analytical applications. Pulsed lasers have been used for non-resonant multiphoton ionization (MPI), resonance-enhanced MPI (REMPI) using tunable wavelengths, and single-photon ionization using sum frequency generation in non-linear media (usually gas cells). Non-laser sources of photoionization include discharge lamps and synchrotron radiation. The former sources were not adaptable to high sensitivity analytical applications because of low spectral brightness in the former case and large "facility-size" in the latter case. Meanwhile, photoionization has been used for GC detection and as a source for ion mobility spectrometry for many years suggesting the potential for use in mass spectrometry. The first development of APPI for LC/MS was reported by Robb, Covey, and Bruins and by Syage, Evans, and Hanold in 2000. APPI sources were commercialized shortly thereafter by Syagen Technology and made available for most commercial MS systems and by Sciex for their line of MS instruments. Concurrent to the development of APPI was a similar use of a VUV source for low pressure photoionization (LPPI) by Syage and coworkers that accepted atmospheric pressure gas phase samples but stepped down the pressure for ionization to about 1 torr (~100 Pa) before further pressure reduction for introduction into a MS analyzer. This photoionization method is well suited as an interface between gas chromatography (GC) and MS.
Scabies (, SKAY-beez; also sometimes known as the seven-year itch) is a contagious human skin infestation by the tiny (0.2–0.45 mm) mite Sarcoptes scabiei, variety hominis. The word is from Latin: scabere, lit. 'to scratch'. It is a particular public health problem in crowded settings such as care homes, schools, refugee camps, prisons, and hospitals. The most common symptoms are severe itchiness and a pimple-like rash. Occasionally, tiny burrows may appear on the skin from eggs that are about to hatch. In a first-ever infection, the infected person usually develops symptoms within three weeks. During a second infection, symptoms may begin within 24 hours. These symptoms can be present across most of the body or just in certain areas such as the wrists, between fingers, or along the waistline. The head may be affected, but this is typically only in young children. The itch is often worse at night. Scratching may cause skin breakdown and an additional bacterial infection in the skin. Various names have been given to this condition and the name "seven year itch" has been recorded in many documents from the 1800s. Although the 1952 play The Seven Year Itch and modern treatment methods have generally changed this name to refer to human relationships, the condition was historically very difficult to treat. Scabies is caused by infection with the female mite Sarcoptes scabiei var. hominis, an ectoparasite. The mites burrow into the skin to live and deposit eggs. The symptoms of scabies are due to an allergic reaction to the mites.
== Overview == Radionuclides occur naturally and are artificially produced in nuclear reactors, cyclotrons, particle accelerators or radionuclide generators. There are 735 known radionuclides with half-lives longer than an hour (see list of nuclides); 35 of those are primordial radionuclides whose presence on Earth has persisted from its formation, and another 62 are detectable in nature, continuously produced either as daughter products of primordial radionuclides or by cosmic radiation. More than 2400 radionuclides have half-lives less than 60 minutes. Most of those are only produced artificially, and have very short half-lives. For comparison, there are 251 stable nuclides.
== Clinical significance == A prolonged stimulation of these cells causes their hyperplasia. This is especially important in gastrinoma (the tumors in which there is an excessive secretion of gastrin), as this is one of the factors contributing to Zollinger–Ellison's syndrome. It was once believed that tumors of ECL origin form after a prolonged inhibition of gastric acid secretion, however there is no data to support this conclusion and proton pump inhibitors are not thought to contribute to gastric cancer.
Sources: en.wikipedia.org
=== Osmium tetroxide === Osmium tetroxide is used in optical microscopy to stain lipids. It dissolves in fats, and is reduced by organic materials to elemental osmium, an easily visible black substance. Because it is a heavy metal that absorbs electrons, it is perhaps the most common stain used for morphology in biological electron microscopy. It is also used for the staining of various polymers for the study of their morphology by TEM. OsO4 is very volatile and extremely toxic. It is a strong oxidizing agent as the osmium has an oxidation number of +8. It aggressively oxidizes many materials, leaving behind a deposit of non-volatile osmium in a lower oxidation state.
Dexamethasone is used to treat many inflammatory and autoimmune disorders, such as rheumatoid arthritis and bronchospasm. Idiopathic thrombocytopenic purpura, a decrease in numbers of platelets due to an immune problem, responds to 40 mg daily for four days; it may be administered in 14-day cycles. It is unclear whether dexamethasone in this condition is significantly better than other glucocorticoids. It is also given in small amounts before and/or after some forms of dental surgery, such as the extraction of the wisdom teeth, an operation that often causes puffy, swollen cheeks. Dexamethasone is commonly given as a treatment for croup in children. A single dose can reduce the swelling of the airway to improve breathing and reduce discomfort. Dexamethasone is sometimes injected into the heel when treating plantar fasciitis or heel pain, sometimes in conjunction with triamcinolone acetonide. There is no evidence that this treatment helps in the long term, however, dexamethasone may provide short-term pain relief. It may be useful to counteract allergic anaphylactic shock, however this is not usually recommended by clinical guidelines. It is present in certain eye drops – particularly after eye surgery – and as a nasal spray, and certain ear drops (can be combined with an antibiotic and an antifungal). Dexamethasone intravitreal steroid implants have been approved by the US Food and Drug Administration (FDA) to treat ocular conditions such as diabetic macular edema, central retinal vein occlusion, and uveitis.
If one of the essential amino acids is not available in the required quantities, protein synthesis will be inhibited, irrespective of the availability of the other amino acids. Protein deficiency has been shown to affect all of the body's organs and many of its systems, for example affecting brain development in infants and young children; inhibiting upkeep of the immune system, increasing risk of infection; affecting gut mucosal function and permeability, thereby reducing absorption and increasing vulnerability to systemic disease; and impacting kidney function. The physical signs of protein deficiency include edema, failure to thrive in infants and children, poor musculature, dull skin, and thin and fragile hair. Biochemical changes reflecting protein deficiency include low serum albumin and low serum transferrin. The amino acids that are essential in the human diet were established in a series of experiments led by William Cumming Rose. The experiments involved elemental diets to healthy male graduate students. These diets consisted of corn starch, sucrose, butterfat without protein, corn oil, inorganic salts, the known vitamins, a large brown "candy" made of liver extract flavored with peppermint oil (to supply any unknown vitamins), and mixtures of highly purified individual amino acids. The main outcome measure was nitrogen balance. Rose noted that the symptoms of nervousness, exhaustion, and dizziness were encountered to a greater or lesser extent whenever human subjects were deprived of an essential amino acid.
Our main concern is the liberation of the blacks." Elsewhere, Biko argued that it was the responsibility of a vanguard movement to ensure that, in a post-apartheid society, the black majority would not seek vengeance upon the white minority. He stated that this would require an education of the black population in order to teach them how to live in a non-racial society.
== History == 2C-EF was originally named by Alexander Shulgin in his 1991 book PiHKAL (Phenethylamines I Have Known and Loved). However, he only speculated about it and never actually synthesized or tested it himself. Subsequently, 2C-EF was synthesized and tested by others such as Daniel Trachsel.
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.
It is a synthetic cyclic peptide designed as an analog of alpha-melanocyte-stimulating hormone. It acts on melanocortin receptors and is best known from research into pigmentation. It is not an approved pharmaceutical product.