This is a working overview of melanocortin, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-09-26 and is reviewed periodically as new material appears.
The compound was developed in the late 1980s and early 1990s by academic researchers investigating melanocortin signaling and pigmentation. Early work explored whether synthetic analogs could reproduce effects of the natural hormone under controlled conditions. The molecule never advanced through the full regulatory pathway required for approval as a medicine. From the mid-2000s onward it appeared in unregulated consumer markets, often distributed through informal channels. That gap between research origins and commercial availability shapes how the compound is discussed today.
Melanotan-2 is a synthetic peptide designed as an analog of alpha-melanocyte-stimulating hormone, a signaling molecule produced in the pituitary and skin. Its structure is a linear chain of seven amino acids that folds into a ring through an internal lactam bridge joining two side chains. The compound is sometimes written as MT-II or MEL-2 in informal and commercial contexts. It belongs to the melanocortin peptide family, a group of short signaling molecules that share a conserved core sequence recognized by melanocortin receptors.
Two structural changes distinguish the synthetic peptide from the natural hormone. A norleucine residue replaces methionine at one position, and a D-configured phenylalanine replaces the natural L-form at another. Both substitutions slow enzymatic breakdown, which extends the molecule's persistence relative to the parent hormone. The lactam bridge further constrains the backbone into a stable conformation. These features are standard design strategies in peptide chemistry and are not unique to this compound; they appear across many research peptides built for improved stability.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic cyclic heptapeptide | Analog of alpha-MSH with an internal lactam bridge |
| Molecular weight | Approximately 1024 daltons | Free base value; salt forms differ |
| Appearance | White to off-white powder | Usually supplied as a lyophilized solid |
| Solubility | Freely soluble in water | Poorly soluble in nonpolar solvents |
| Typical storage | −20 °C, dry, protected from light | Repeated freeze-thaw cycles degrade peptides |
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.
Verification of a purchased sample requires documentation linking a batch to a certificate of analysis, and that document should be read for the methods used rather than the headline purity figure. A single chromatographic percentage does not establish identity. Independent laboratories can perform identity and content assays, but no such test establishes that a product is suitable for human use. Claims about efficacy rest largely on small, early studies rather than on replicated controlled trials, and that gap remains open.
Identity testing for a cyclic peptide of this size usually relies on reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The mass spectrum confirms molecular weight, while the chromatographic trace indicates the proportion of related impurities. Tandem mass spectrometry can provide sequence-level information when fragmentation data are compared against a reference standard. Nuclear magnetic resonance is sometimes used to confirm the lactam bridge, although it requires more material and greater operator expertise than routine chromatographic methods.
=== Motility disorders === Several disorders affect the motility of food as it travels down the esophagus. This can cause difficult swallowing, called dysphagia, or painful swallowing, called odynophagia. Achalasia refers to a failure of the lower esophageal sphincter to relax properly, and generally develops later in life. This leads to progressive enlargement of the esophagus, and possibly eventual megaesophagus. A nutcracker esophagus refers to swallowing that can be extremely painful. Diffuse esophageal spasm is a spasm of the esophagus that can be one cause of chest pain. Such referred pain to the wall of the upper chest is quite common in esophageal conditions. Sclerosis of the esophagus, such as with systemic sclerosis or in CREST syndrome may cause hardening of the walls of the esophagus and interfere with peristalsis.
=== Lethality === The mean lethal dose in rats (i.p.) for ATR is 143 mg/kg and for CATR is 2.9 mg/kg. This lethal dose of ATR takes approximately 150–180 minutes after injection until acute tubular necrosis occurred. This lethal dose varies across species and method of exposure. For example, the mean lethal dose of ATR in rats (s.c.) is 155 mg/kg. Published mean lethal doses of ATR in other species includes 250 mg/kg (s.c.) for rabbit, 200 mg/kg (i.p.) for guinea pig, and 15 mg/kg (i.v.) for dog.
Liposomes, for instance, are small vesicles that can carry drugs and be modified to circulate longer or home in on specific brain regions. Dendrimers, with their tree-like structure, can hold multiple drug molecules and targeting agents at once. Polymeric nanoparticles, made from biodegradable materials like polylactic acid (PLA) or polylactic-co-glycolic acid (PLGA), can be engineered to release drugs over time in a controlled way. Solid lipid nanoparticles offer another alternative, combining biocompatibility with the ability to cross barriers more efficiently. Altogether, these advances are paving the way for more effective and precise treatments for a range of neurological disorders. Nanotechnology helps to transfer medicine to specific places in the body. Drug delivery in new forms with the assistance of minute particles, like liposomes or polymeric micelles. These particles support the drugs by preventing disintegration and enhancing functionality (Islam et al., 2025). An example would be, they can distribute cancer drugs to the tumors, which reduce the side effects. Researchers also come up with particles, which release drugs when going through certain conditions like heat or light. Despite the nature of this technology, it remains expensive and needs further safety studies. In the near future researchers say there will be a more advanced strategies of treatment such as the use nanomedicine and technology like artificial intelligence (Islam et al., 2025).
=== Medical === Puffballs are a known styptic and have long been used as wound dressing, either in powdered form or as slices 3 cm thick. Authors Hui-Yeng Y. Yap, Mohammad Farhan Ariffeen Rosli, et al. found evidence to suggest that C. gigantea was "traditionally used by American Indians, Nigerian and German folks" for this purpose. The authors, however, did not specify the preferred form of wound dressing (e.g., powdered or sliced). In addition to consuming the mushroom, the Māori people of New Zealand used it to stem bleeding and treat burns.
Sources: en.wikipedia.org
== Competitions == The ARL controls the National Rugby League and NRL Women's Premiership as well as annual representative competitions such as the State of Origin series, the Indigenous All Stars Match, the Affiliated States Championship and the Women's National Championships. The ARL previously ran the National Youth Competition. This competition, which was for male players Under 20 years of age, was replaced in 2018 by state-run competitions. The New South Wales Rugby League run the Jersey Flegg Cup for male Under 21 players. The Queensland Rugby League run the Mal Meninga Cup for male Under 18 players, with players Under 21 that are outside NRL squads playing for clubs in the open-age Queensland Cup.
A variety of plants have provided indigo throughout history, but most natural indigo was obtained from those in the genus Indigofera, which are native to the tropics, notably the Indian Subcontinent. The primary commercial indigo species in Asia was true indigo (Indigofera tinctoria, also known as I. sumatrana). A common alternative used in the relatively colder subtropical locations such as Japan's Ryukyu Islands and Taiwan is Strobilanthes cusia. Until the introduction of Indigofera species from the south, Persicaria tinctoria (dyer's knotweed) was the most important blue dyestuff in East Asia; however, the crop produced less dyestuff than the average crop of indigo, and was quickly surpassed in favour of the more economical Indigofera tinctoria plant. In Central and South America, the species grown is Indigofera suffruticosa, also known as anil, and in India, an important species was Indigofera arrecta, Natal indigo. In Europe, Isatis tinctoria, commonly known as woad, was used for dyeing fabrics blue, containing the same dyeing compounds as indigo, also referred to as indigo. Several plants contain indigo, which, when exposed to an oxidizing source such as atmospheric oxygen, reacts to produce indigo dye; however, the relatively low concentrations of indigo in these plants make them difficult to work with, with the color more easily tainted by other dye substances also present in these plants, typically leading to a greenish tinge.
Trans fats occur in meat and dairy products from ruminants. For example, butter contains about 3% trans fat by weight. These naturally occurring trans fats include conjugated linoleic acid (CLA) and vaccenic acid (trans-11 18:1). They arise from the action of bacteria in the rumen. Polyunsaturated fats are toxic to the rumen-based bacteria, which detoxify the fats by changing some cis-double bonds to trans-double bonds. In contrast to industrially produced trans fats, this bacterial process produces only a few specific isomers. Conjugated trans fatty acids such as CLA are exempt from counting as trans fat in the US. The Codex Alimentarius includes an analogous exclusion. As industrial sources of trans fats are eliminated, increased attention focuses on ruminant derived trans fats. Not all ruminant-derived trans fats are innocuous like vaccenic acid and its metabolite rumenic acid (cis-9-trans-11 CLA / 18:2). In particular, trans-10 18:1 is not turned into a conjugated linoleic acid by humans. It appears to have health consequences comparable to trans fats of industrial origin.
=== 23 October === A third drone attack was carried out on Khartoum International Airport. Five people were killed in a drone strike on a market in El Fasher. The Central Bank of Sudan froze the assets of former prime minister Abdalla Hamdok and 38 other politicians on charges of supporting the RSF.
==== Plain radiography (X-ray) ==== It is difficult to distinguish NF from cellulitis in earlier stages of the disease using plain radiography. X-rays can detect subcutaneous emphysema (gas in the subcutaneous tissue), which is strongly suggestive of necrotizing changes. However, air is often a late-stage finding, and not all necrotizing skin infections create subcutaneous emphysema. Hence, radiography is not recommended for the initial diagnosis of NF. However, it may be able to identify the source of infection, such as foreign bodies or fractures, and thus aid in subsequent treatment.
Sources: en.wikipedia.org
== Lysosomal Ca2+-signalling modalities == The ER and acidic Ca2+ stores have similarities as well as key differences. Both transport Ca2+ into their lumina where it is stored, and is subsequently released in response to stimuli by opening resident Ca2+ channels. Indeed, the free [Ca2+] of each is broadly similar (~0.5-1.0 mM). However, they differ in the cohort of transporters, their luminal pH and their total volume per cell. The total amount of Ca2+ that is stored in each is a product of the volume and concentration; since the [Ca2+] is the same for each, the total amount of releasable Ca2+ is directly proportional to the organellar volume and therefore lysosomes can release only a small amount Ca2+ of when compared to the ER. This is important because the maximal Ca2+ release from lysosomes is so small that it is frequently 'invisible' in global Ca2+ recordings e.g. using cytosolic fluorescent reporters. In contrast, ER-derived Ca2+ is globally substantial and the predominant intracellular signal visible in global recordings. If lysosomal Ca2+ release is so small, how then can it affect cellular physiology? The answer is that it can exert its effects in two different signalling modalities: local and global, as shall be described. In bacterial infection, however, NAADP induction of lysosomal Ca2+ efflux and TFEB activation leads to enhanced expression of inflammatory cytokines.
=== Others === HiBiT-tag was developed by Scientists at Promega. It is an 11-amino-acid peptide tag, and it can be fused to the N- or C-terminus or internal locations of proteins. Its small size leads to a rapid knock-in of this tag with other proteins through CRISPR/Cas9 technology.
, contains the bulk modulus K. If K is frequency-independent, then the liquid behaves as a linear medium, so that sound propagates without dissipation or mode coupling. In reality, all liquids show some dispersion: with increasing frequency, K crosses over from the low-frequency, liquid-like limit
In a 3 January 2026 editorial, The New York Times editorial board condemned the attack as "dangerous and illegal", describing it as an act of "latter-day imperialism" which lacked "any semblance of international legitimacy, valid legal authority or domestic endorsement". Comparing the attack to interventions in Libya, the war in Afghanistan, and US involvement in Nicaragua, it warned of the "potential for chaos in Venezuela", including violence from paramilitary groups such as the Venezuelan colectivos or the Colombian National Liberation Army (ELN), which operates in western Venezuela. The AFL-CIO condemned the attack, calling it unconstitutional. Many analysts liken the operation in Venezuela to prior operations, such as Operation Nifty Package which led to the capture of Panamanian military leader, Manuel Noriega, as well as Operation Red Dawn, which led to the capture of former Iraqi president, Saddam Hussein.
== Education == Gibson was educated at Darwen Vale High School and the University of Cambridge as an undergraduate student of Sidney Sussex College, Cambridge, where she studied the Natural Sciences Tripos. She completed postgraduate study at the University of Oxford as a student of New College, Oxford where she obtained a Doctor of Philosophy degree in Chemistry in 1984 for research supervised by Stephen G. Davies.
Sources: en.wikipedia.org
It is a synthetic seven-amino-acid peptide modeled on alpha-melanocyte-stimulating hormone. It carries two non-natural substitutions and a cyclic bridge that increase its stability relative to the natural hormone. It circulates as a research chemical and is not an approved medicine.
Melanotan-1, also called afamelanotide, is a shorter linear analog with a different amino acid sequence and no lactam ring. It has been evaluated in formal clinical programs, while melanotan-2 has not. The two are distinct molecules and are not interchangeable.
No. Bremelanotide is a related but distinct cyclic peptide that reached approved status for one specific clinical indication. Melanotan-2 is a separate molecule with its own sequence and properties. Shared ancestry in the melanocortin family does not make them the same substance.
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.