The short version of Melanotan II fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-04-06. Anything still debated is marked as such rather than presented as settled.
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.
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 |
|---|---|---|
| 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 |
Regulatory treatment varies between countries. Several national medicines agencies have classified the peptide as unapproved, and customs authorities in some jurisdictions seize shipments on that basis. A few jurisdictions channel supply through prescription-only frameworks that do not list the substance by name. Because the material circulates mainly through online vendors, composition and purity are rarely verified before sale. Surveys of unapproved peptide products have reported labels that did not match measured content in a substantial fraction of samples.
Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its structure substitutes a lactam bridge between side chains to increase stability relative to the native hormone. The compound is also known by the shorthand MT-II and by several non-proprietary synonyms used in research catalogues. It is not an approved therapeutic product in any major jurisdiction; material sold under this name is typically offered as a laboratory reagent rather than as a medicine.
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
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.
== Research == A relatively recent avenue of drug research in treating depression and drug addiction is through PPARα and PPARγ activation. Both TLR4-mediated and NF-κB-mediated signalling pathways have been implicated in the development of addiction to several drugs such as opioids and cocaine, and therefore are appealing targets for pharmacotherapy. Despite a breadth of preclinical research showing potential in animal models in the treatment of drug addictions including alcohol, nicotine, cocaine, opioids and methamphetamine, the human evidence is limited with the amount of trials looking at using PPAR agonists for humans still being low; and so far (as of 2020) not being particularly promising. There are several suggested hypotheses for the poor translation from animal to human research evidence such as the potency and selectivity of PPAR ligands, sex-related variability, and species differences in the distribution and signaling of PPAR.
== OSCE monitors == A former senior Organization for Security and Co-operation in Europe (OSCE) official, Ryan Grist, who was responsible for monitors in South Ossetia at war's start, told the BBC in November 2008 that he had been warning of Georgian military movement before the full-scale war, saying there was a "severe escalation" and that this "would give the Russian Federation any excuse it needed in terms of trying to support its own troops." According to Grist, the first attack on Tskhinvali came from Georgia, which "was completely indiscriminate and disproportionate to any, if indeed there had been any, provocation." Grist's views were echoed by Stephen Young, who was another senior OSCE official in Georgia at the time. According to him, there had been no large-scale shelling of the Georgian villages on late 7 August. Young added, that if Georgian villages had been shelled heavily that evening, the OSCE monitors at the scene would have heard it. According to him, "only occasional small arms fire" was heard. Georgian officials and some Western diplomats in Tbilisi later disputed Grist's neutrality. The attempts by The New York Times to interview the monitors were curbed by the OSCE. The OSCE sought to avoid open involvement in dispute. The monitors' claims were assessed as "a bit irrelevant" by head of the OSCE mission to Georgia Terhi Hakala.
==== Stages of genital development ==== The first stage occurs roughly four weeks before the spider's final molt. Unlike adult males, young males possess a broad tarsus that does not appear to consist of any internal structures or appendages. Their pedipalps are greatly bent at a joint connecting the between the tibia and patella. The testes at this point in the young male's life appear very similar to those of the adult males both in terms of physical structure and presence of all stages of spermatogenesis. This spermatogenesis takes place in cysts which contain spermatids. During this time, there is very little observable secretory activity in the testes. In a similar manner to the adult genital system, the vas deferens in young males is connected to the distal, thin part of the testis. The distal portion of the vas deferens is incredibly narrow and is not characterized by the presence of spermatozoa or other secretions. On the other hand, the proximal region consists of a thick epithelium and intricate luminal region containing spermatozoa. The second stage of development is observed two weeks prior the spider's final molt. At this point, the pedipalps of the spider are only partially bent, and the internal structures of the tarsus can be seen. The testes are dimensionally very similar to those of subadult stage one males and adult males. The distal portion of the vas deferens becomes thinner and twists in a tube-like shape. Spermatozoa and other secretions are extensively present in proximal portion of the vas deferens.
== Function == Mitochondrial aldehyde dehydrogenase belongs to the aldehyde dehydrogenase family of enzymes that catalyze the chemical transformation from acetaldehyde to acetic acid. Aldehyde dehydrogenase is the second enzyme of the major oxidative pathway of alcohol metabolism. Human ALDH2 is especially efficient on acetaldehyde compared to ALDH1.
Sources: en.wikipedia.org
In the Egyptian, Greek and Roman Empires, women usually fed only their own children. However, breastfeeding began to be seen as something too common to be done by royalty. Wet nurses were employed to breastfeed the children of the royal families. This extended over time, particularly in western Europe, where noble women often used wet nurses. Lower-class women breastfed their infants and used a wet nurse only if they were unable to feed their own infant. Attempts were made in 15th-century Europe to use cow or goat milk, but these attempts were unsuccessful. In the 18th century, flour or cereal mixed with broth was introduced as a substitute for breastfeeding, but this provided inadequate nutrition. The appearance of improved infant formulas in the mid-19th century and their increased use caused a decrease in breastfeeding rates, which accelerated after World War II. For some in the US, Canada, and the UK, breastfeeding was seen as uncultured. From the 1960s onwards, breastfeeding experienced a revival that continued into the 2000s, though negative attitudes towards the practice were still entrenched in some countries up to the 1990s.
=== Bibliography === Algar, Hamid (1989). "BEKTĀŠĪYA". Encyclopaedia Iranica. Vol. IV. pp. 118–122. Doja, Albert. 2006. "A political history of Bektashism from Ottoman Anatolia to Contemporary Turkey." Journal of Church and State 48 (2): 421–450. doi=10.1093/jcs/48.2.423. Doja, Albert. 2006. "A political history of Bektashism in Albania." Politics, Religion & Ideology 7 (1): 83–107. doi=10.1080/14690760500477919. Elsie, Robert (2001). A Dictionary of Albanian Religion, Mythology and Folk Culture. New York: New York University Press. ISBN 978-1-85065-570-1. Nicolle, David; UK (1995). The Janissaries (5th). Osprey Publishing. ISBN 1-85532-413-X. Muhammed Seyfeddin Ibn Zulfikari Derviş Ali; Bektaşi İkrar Ayini, Kalan Publishing, Translated from Ottoman Turkish by Mahir Ünsal Eriş, Ankara, 2007 Turkish Saggau, Emil BH. "Marginalised Islam: Christianity's role in the Sufi order of Bektashism." In Exploring the Multitude of Muslims in Europe, pp. 183–197. Brill, 2018. Soileau, Mark (2014). "Conforming Haji Bektash: A Saint and His Followers between Orthopraxy and Heteropraxy." Die Welt des Islams 54, pp. 423-459
The Rhodesian African Rifles were based at Borrowdale in north-east Salisbury between 1940 and 1943. Apart from a contingent sent south to Durban to guard Italian prisoners on their way to Rhodesia, the regiment's main role was garrison duties within the colony. The Rhodesian Air Askari Corps, a unit of black volunteer troops under white command, guarded the air bases and also provided manpower for non-armed labour. The perceived possibility that Japan might attempt an invasion of southern Africa via Madagascar led to the consolidation of a few hundred rural whites into the Southern Rhodesia Commando, a part-time cadre intended as the basis for a guerrilla-style resistance movement, from 1942. The mobilisation of white British South Africa Police officers for military service led to black male and white female constables taking on higher responsibilities. The BSAP recruited more black patrolmen to accommodate the growth of the urban black population during the war, going from 1,067 black and 547 white personnel in 1937 to 1,572 blacks and 401 whites in 1945. This "Africanisation" led to higher appreciation for black constables among senior policemen and the public. The police remained rigidly segregated, but black constables received uniforms more similar to those of their white counterparts, and the nominal distinction between the BSAP "proper" and the British South Africa Native Police—the "force within the force" black personnel were traditionally regarded as members of—was abolished.
=== Cognitive problems ("fibro fog") === Many people with fibromyalgia experience cognitive problems often known as "fibro fog". The CDC and the American Pain Society recognize these problems as a major feature of fibromyalgia. About 75% of people with fibromyalgia report significant problems with concentration, memory, and multitasking. A 2018 meta-analysis found that the largest differences between people with fibromyalgia and healthy subjects were in inhibitory control, memory, and processing speed. A 2023 scoping review grouped effects into subjective cognitive dysfunction, perceived variability, changes in functional activities, and participation limitations. A 2017 review found that the neuropsychological mechanisms underlying brain fog may be similar to those in isolated functional cognitive disorders. One hypothesis is that chronic pain in fibromyalgia compromises attention systems, resulting in cognitive problems.
is the unit tensor. This equation can be thought of as a generalized form of Newton's law of viscosity. The bulk viscosity (also called volume viscosity) expresses a type of internal friction that resists the shearless compression or expansion of a fluid. Knowledge of
Sources: en.wikipedia.org
Finnegan (1928), director of the Federal Mediation and Conciliation Service 1955–1961 Wolf Ladejinsky (1928), agricultural economist and researcher and key adviser on land reform in Asian countries James T. O'Connell (1928), U.S. deputy secretary of labor 1957–1961 James J. Reynolds (1928), U.S. deputy secretary of labor 1967–1969 William H. Shaw (1930), assistant secretary of commerce for Economic Affairs 1966–1968 Boris Shishkin (1930), member of the President's Committee on Civil Rights and head of the AFL–CIO Department of Civil Rights Arthur E. Goldschmidt (1932), United States ambassador to the United Nations Economic and Social Council 1967–1969 Reed Harris (1932), former deputy director of the United States Information Agency and victim of McCarthyism James Hagerty (1934), White House press secretary 1953–1961 Hickman Price (1934), assistant secretary in the United States Department of Commerce 1961–1963; Kaiser-Frazer and Willys executive Faubion Bowers* (1935), General Douglas MacArthur's interpreter and aide-de-camp during the Allied Occupation of Japan Hunter Meighan (1935), member of the New York State Assembly and the New York State Senate Thomas Karamessines (1938), deputy director of CIA for operations 1967–1973 A. Gerdes Kuhbach (1938), executive director of the Port Authority of New York and New Jersey 1973–1977 Thibaut de Saint Phalle (1939), director of the Export–Import Bank of the United States 1977–1981 Arthur R. Albohn (1942), member of the New Jersey General Assembly Richard T. Davies (1942), former U.S. ambassador to Poland David E.
=== Equipment loan program === Upon the conclusion of the SHIELD Illinois testing program, laboratory equipment and other hard assets were offered to public entities throughout the State of Illinois at no cost with the understanding that, should another pandemic occur, the equipment would be used however necessary to continue the mission of SHIELD Illinois to keep Illinois open.
The terms "molecular mass", "molecular weight", and "molar mass" may be used interchangeably in less formal contexts where unit- and quantity-correctness is not needed. The molecular mass is more commonly used when referring to the mass of a single or specific well-defined molecule and less commonly than molecular weight when referring to a weighted average of a sample. Prior to the 2019 revision of the SI, quantities expressed in daltons (Da) were by definition numerically equivalent to molar mass expressed in the units g/mol and were thus strictly numerically interchangeable. After the 2019 revision, this relationship is only approximate, but the equivalence may still be assumed for all practical purposes. The molecular mass of small to medium size molecules, measured by mass spectrometry, can be used to determine the composition of elements in the molecule. The molecular masses of macromolecules, such as proteins, can also be determined by mass spectrometry; however, methods based on viscosity and light-scattering are also used to determine molecular mass when crystallographic or mass spectrometric data are not available.
=== Form factor === The physical design of refrigerators also plays a large part in its energy efficiency. The most efficient is the chest-style freezer, as its top-opening design minimizes convection when opening the doors, reducing the amount of warm moist air entering the freezer. On the other hand, in-door ice dispensers cause more heat leakage, contributing to an increase in energy consumption.
Freshwater is a renewable resource, recirculated by the natural hydrologic cycle, but pressures over access to it result from the naturally uneven distribution in space and time, growing economic demands by agriculture and industry, and rising populations. Currently, nearly a billion people around the world lack access to safe, affordable water. In 2000, the United Nations established the Millennium Development Goals for water to halve by 2015 the proportion of people worldwide without access to safe water and sanitation. Progress toward that goal was uneven, and in 2015 the UN committed to the Sustainable Development Goals of achieving universal access to safe and affordable water and sanitation by 2030. Poor water quality and bad sanitation are deadly; some five million deaths a year are caused by water-related diseases. The World Health Organization estimates that safe water could prevent 1.4 million child deaths from diarrhea each year. In developing countries, 90% of all municipal wastewater still goes untreated into local rivers and streams. Some 50 countries, with roughly a third of the world's population, also suffer from medium or high water scarcity and 17 of these extract more water annually than is recharged through their natural water cycles. The strain not only affects surface freshwater bodies like rivers and lakes, but it also degrades groundwater resources.
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.
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.