The short version of afamelanotide fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-03-14. Anything still debated is marked as such rather than presented as settled.
Because the substance circulates mainly through informal markets, verification is a recurring theme in technical discussion. Independent analyses have found that labeled content and actual content can diverge, and that purity varies between samples. Analytical laboratories use reversed-phase chromatography to separate components and mass spectrometry to confirm identity. Isotope-labeled internal standards improve quantification in complex matrices. Such methods describe what a sample contains but say nothing about its sterility, lawful status, or suitability for any use. Open questions remain about how consistently testing is applied across the supply chain.
Regulatory treatment of this peptide varies by country. It holds no marketing authorization as a medicine in the United States, the European Union, or most other jurisdictions. Some countries classify products containing it as prescription-only or unlicensed medicines, which restricts lawful supply. Authorities have issued public notices warning that unregulated products may contain undeclared or incorrect ingredients. The molecule also appears on prohibited lists for competitive sport. These measures address supply oversight rather than any approved therapeutic role.
Published research on the compound remains limited. Much of the human data comes from small, early-stage studies rather than large controlled trials, and several questions about effects and variability between individuals remain open. Investigators have examined receptor activity, pigment pathways, and related physiological responses in laboratory and animal models. Findings from those models do not automatically translate to human outcomes. Reviews frequently note the scarcity of rigorous clinical evidence and call for better-characterized study material.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Regulatory status | Not approved as a medicine | No marketing authorization in major jurisdictions |
| Scheduling example | Prescription-only supply in some countries | Handled as an unlicensed medicine where restricted |
| Sports classification | Prohibited peptide | Appears on anti-doping prohibited lists |
| Reported presentation | Lyophilized vial | Nominal content varies between vendors |
| Detection approach | Liquid chromatography–tandem mass spectrometry | Used in anti-doping and forensic testing |
Independent verification is central to quality control because the compound is not produced under pharmaceutical manufacturing standards. Third-party laboratories can measure purity, identity, residual solvents, and microbial contamination, though the scope of testing varies between services. Reported analyses of vendor samples have shown batch-to-batch variation in peptide content and the presence of truncated or oxidized species. How much of this variation reflects synthesis conditions versus storage and shipping is not well characterized. No harmonized reference standard exists for the material as sold.
Handling guidance for melanotan II follows general practice for small synthetic peptides rather than a product-specific monograph. Lyophilized powder is typically kept at minus twenty degrees Celsius or colder, protected from light and moisture, because warmth and humidity accelerate degradation. Once reconstituted, solutions are usually refrigerated and used within a short window, as hydrolysis and microbial growth both become concerns. Repeated freeze-thaw cycles are generally avoided. These conventions come from laboratory peptide chemistry and not from formal stability studies on this specific compound.
Analytical confirmation of identity relies on mass spectrometry, most often coupled to liquid chromatography. Reversed-phase high-performance liquid chromatography separates the peptide from related impurities and provides a purity estimate based on peak area. Electrospray ionization mass spectrometry then confirms the expected molecular mass, while tandem mass spectrometry can map the fragment sequence. For research-grade material, these two techniques together form the standard minimum. Purity figures reported by vendors are frequently not traceable to an independent laboratory.
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.
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.
The simple, or top-up transfusion, is a procedure in which healthy blood cells from a donor are infused into the patient's bloodstream. This benefits by alleviating anaemia, increasing tissue oxygen levels, reducing the risk of sickling, and relieving sickling symptoms. A simple transfusion can be used to treat sickle cell disease when haemoglobin levels drop too low, or to prepare for an operation or pregnancy. It can also be used to protect against long-term complications or to reduce the risk of stroke. An exchange transfusion is a procedure in which blood is removed from the body, then processed to extract sickled cells, which are replaced by healthy red blood cells from a donor. The treated blood, including white cells and plasma, is then returned to the patient. Exchange transfusions are likely to be needed in an emergency, in severe cases of sickle cell disease, or to support a mother during pregnancy.
In morphology, analogous traits arise when different species live in similar ways and/or a similar environment, and so face the same environmental factors. When occupying similar ecological niches (that is, a distinctive way of life) similar problems can lead to similar solutions. The British anatomist Richard Owen was the first to identify the fundamental difference between analogies and homologies. In biochemistry, physical and chemical constraints on mechanisms have caused some active site arrangements such as the catalytic triad to evolve independently in separate enzyme superfamilies. In his 1989 book Wonderful Life, Stephen Jay Gould argued that if one could "rewind the tape of life [and] the same conditions were encountered again, evolution could take a very different course." Simon Conway Morris disputes this conclusion, arguing that convergence is a dominant force in evolution, and given that the same environmental and physical constraints are at work, life will inevitably evolve toward an "optimum" body plan, and at some point, evolution is bound to stumble upon intelligence, a trait presently identified with at least primates, corvids, and cetaceans.
On March 13, 2019, three years after voters narrowly rejected its repeal in the 2016 California Proposition 62, Newsom declared a moratorium on the state's death penalty, preventing any execution in the state as long as he remained governor. The move also led to the withdrawal of the state's current lethal injection protocol and the execution chamber's closure at San Quentin State Prison. In a CBS This Morning interview, Newsom said that the death penalty is "a racist system ... that is perpetuating inequality. It's a system that I cannot in good conscience support." The moratorium granted a temporary reprieve for all 737 inmates on California's death row, then the largest death row in the Western Hemisphere. In January 2022, Newsom directed the state to begin dismantling its death row in San Quentin, to be transformed into a "space for rehabilitation programs", as all the condemned inmates were moving to other prisons that have maximum security facilities. The state's voters upheld capital punishment in 2012 and 2016, agreeing when they did so in 2016 to move the condemned to other prisons. While a 2021 poll by the UC Berkeley Institute of Governmental Studies and co-sponsored by the Los Angeles Times suggested declining support for capital punishment among California's voters, Republican opponents criticized Newsom's moves to halt capital punishment in California as defiance of the will of voters, and capital punishment advocates said they denied closure to murder victims' families.
=== Aquaporin-Z === AqpZ, a homotetramer (tAqpZ) of four water-conducting channels that facilitate rapid water movements across the plasma membrane of E. coli, has been solved to 3.2 Å resolution (PDB: 2ABM). All channel-lining residues in the four monomeric channels are orientated in nearly identical positions except at the narrowest channel constriction, where the side chain of a conserved Arg-189 adopts two distinct orientations. In one of the four monomers, the guanidino group of Arg-189 points toward the periplasmic vestibule, opening up the constriction to accommodate the binding of a water molecule through a tridentate H-bond. In the other three monomers, the Arg-189 guanidino group bends over to form an H-bond with carbonyl oxygen of Thr-183 occluding the channel. Therefore, the tAqpZ structure has two different Arg-189 conformations which provide water permeation through the channel. Alternating between the two Arg-189 conformations disrupts continuous flow of water, thus regulating the open probability of the water pore. Further, the difference in Arg-189 displacements is correlated with a strong electron density found between the first transmembrane helices of two open channels, suggesting that the observed Arg-189 conformations are stabilized by asymmetrical subunit interactions in tAqpZ. Other resolved crystal structures for AqpZ include: PDB: 3NK5 , 3NKC, 1RC2.
== Biosynthesis == The biosynthesis of eugenol begins with the amino acid tyrosine. L-tyrosine is converted to p-coumaric acid by the enzyme tyrosine ammonia lyase (TAL). From here, p-coumaric acid is converted to caffeic acid by p-coumarate 3-hydroxylase using oxygen and NADPH. S-Adenosyl methionine (SAM) is then used to methylate caffeic acid, forming ferulic acid, which is in turn converted to feruloyl-CoA by the enzyme 4-hydroxycinnamoyl-CoA ligase (4CL). Next, feruloyl-CoA is reduced to coniferyl aldehyde by cinnamoyl-CoA reductase (CCR). Coniferyl aldehyde is then further reduced to coniferyl alcohol by cinnamyl-alcohol dehydrogenase (CAD) or sinapyl-alcohol dehydrogenase (SAD). Coniferyl alcohol is then converted to an ester in the presence of the substrate CH3COSCoA, forming coniferyl acetate. Finally, coniferyl acetate is converted to eugenol via the enzyme eugenol synthase 1 and the use of NADPH. Eugenol is a metabolite of caleicine, the active compound found in Calea ternifolia, and is thought to cause the sedative and hallucinogenic state C. ternifolia can induce.
Sources: en.wikipedia.org
For services to Association Football and to Gender Equality. Rajwinder Singh. Principal Project Sponsor, Prison Infrastructure Team, Ministry of Justice. For Public Service. Dr. Sabesan Sithamparanathan, FREng. Founder and President, PervasID and Enterprise Fellow, Girton College, University of Cambridge. For services to Innovation Technology. David Alexander Smith. Departmental Records Officer and Chief Librarian, Department for Levelling Up, Housing and Communities. For services to Government Knowledge and Information Management. Marie Smith. Senior Officer, National Crime Agency. For services to Law Enforcement. Michelle Southern. Founder and Director, Street Paws. For services to Homeless People and their Pets. David Martin Sprackling. Lately Lawyer, Parliamentary Counsel, Office of the Parliamentary Counsel. For Public Service. Nicholas Stace. Chair, The Conduit Holding Company. For services to Consumers and to the Environment. Marc Howard Steene. Founder and Director, Outside In Art. For services to Art. Gavin Paul Stollar. Honorary Chair, Liberal Democrat Friends of Israel. For political service to the Jewish Community. Luigi Strinati. Delivery Director, HM Courts and Tribunals Service Wales. For Public Service. Lorraine Pfavayi Sunduza. Lately Chief Nurse, East London NHS Foundation Trust. For services to Mental and Community Health. Joanna Kathryn Swash. Group Chief Executive Officer, Moneypenny. For services to the Economy. Claire Louise Swift. Director of Social Responsibility, Making for Change. For services to the Rehabilitation of Prisoners.
The exterior of an individual segment is a thin cuticle over the skin, commonly pigmented red to brown, which has specialized cells that secrete mucus over the cuticle to keep the body moist and ease movement through the soil. Under the skin is a layer of nerve tissue, and two layers of muscles—a thin outer layer of circular muscle, and a much thicker inner layer of longitudinal muscles. Interior to the muscle layer is a fluid-filled chamber called a coelom that by its pressurization provides structure to the worm's boneless body. The segments are separated from each other by septa (the plural of "septum") which are perforated transverse walls, allowing the coelomic fluid to pass between segments. A pair of structures called nephrostomes are located at the back of each septum; a nephric tubule leads from each nephrostome through the septum and into the following segment. This tubule then leads to the main body fluid filtering organ, the nephridium or metanephridium, which removes metabolic waste from the coelomic fluid and expels it through pores called nephridiopores on the worm's sides; usually, two nephridia (sometimes more) are found in most segments. At the centre of a worm is the digestive tract, which runs straight through from mouth to anus without coiling, and is flanked above and below by blood vessels (the dorsal blood vessel and the ventral blood vessel as well as a subneural blood vessel) and the ventral nerve cord, and is surrounded in each segment by a pair of pallial blood vessels that connect the dorsal to the subneural blood vessels.
==== Anglo-American ==== Richard Steiff, the creator of the teddy bear, made the toy in 1902 under Margarete Steiff's felt goods company. The toys were brought to the US and gained mass popularity after a newspaper told the story of Theodore Roosevelt refusing to shoot a black bear cub tied to a tree. The fictional character Winnie-the-Pooh was named after Winnipeg, a female cub that lived at the London Zoo from 1915 until her death in 1934. A cub, who in the spring of 1950 was caught in the Capitan Gap Fire, was made into the living representative of Smokey Bear, the mascot of the United States Forest Service. Terrible Ted was a de-toothed and de-clawed bear who was forced to perform as a pro wrestler and whose "career" lasted from the 1950s to the 1970s. Clark's Bears, previously named Clark's Trading Post, is a visitor attraction in Lincoln, New Hampshire known for its trained bear shows since 1949. The American black bear is the mascot of the University of Maine and Baylor University, the latter of which houses two live bears on campus.
=== Cytoprotective effects === When APC is bound to EPCR, it performs a number of important cytoprotective (i.e. cell-protecting) functions, most of which are known to require EPCR and PAR-1. These include regulating gene expression, anti-inflammatory effects, antiapoptotic effects and protecting endothelial barrier function. Treatment of cells with APC demonstrates that its gene expression modulation effectively controls major pathways for inflammatory and apoptotic behaviour. There are about 20 genes that are up-regulated by protein C, and 20 genes that are down-regulated: the former are generally anti-inflammatory and antiapoptotic pathways, while the latter tend to be proinflammatory and proapoptotic. APC's mechanisms for altering gene expression profiles are not well understood, but it is believed that they at least partly involve an inhibitory effect on transcription factor activity. Important proteins that APC up-regulates include Bcl-2, eNOS and IAP. APC effects significant down-regulation of p53 and Bax. APC has anti-inflammatory effects on endothelial cells and leukocytes. APC affects endothelial cells by inhibiting inflammatory mediator release and down-regulating vascular adhesion molecules. This reduces leukocyte adhesion and infiltration into tissues, while also limiting damage to underlying tissue. APC supports endothelial barrier function and reduces chemotaxis.
=== HPLC-based === A faster method of log P determination makes use of high-performance liquid chromatography. The log P of a solute can be determined by correlating its retention time with similar compounds with known log P values. An advantage of this method is that it is fast (5–20 minutes per sample). However, since the value of log P is determined by linear regression, several compounds with similar structures must have known log P values, and extrapolation from one chemical class to another—applying a regression equation derived from one chemical class to a second one—may not be reliable, since each chemical classes will have its characteristic regression parameters.
Sources: en.wikipedia.org
Only a small number of early-stage human studies have been reported, and most were limited in size and duration. No large late-stage program has established a general efficacy or safety profile. The evidence base is therefore thin compared with approved medicines.
The peptide is listed as prohibited in competitive sport, so laboratories develop detection methods and monitor for its presence. Its appearance in enforcement reports reflects that classification rather than any approved athletic use. Analytical work in this area focuses on identifying the molecule and its breakdown products in biological samples.
Chromatographic separation combined with mass spectrometry identifies the peptide and estimates its amount in a sample. Testing can confirm whether the expected molecule is present and at what concentration. It cannot establish how a product was manufactured or whether it meets any purity standard.
It is a synthetic cyclic heptapeptide and a non-selective melanocortin receptor agonist. Structurally it is modelled on alpha-melanocyte-stimulating hormone, a peptide that occurs naturally in the body.