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Chemistry And Receptor Pharmacology — Quick Reference

By Editorial Desk · published 2026-04-15 · last reviewed 2026-06-05 · Guide

The short version of Melanotan II fits in a sentence. The long version — which is the one that helps — is below.

This page was last updated on 2026-06-05 and is reviewed periodically as new material appears.

Chemistry and Receptor Pharmacology

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.

Origins and Research Status

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.

Melanotan-2 at a glance

PropertyValueNotes
Molecular formulaC50H69N15O9Cyclic heptapeptide, C-terminally amidated
Approximate molecular mass1024 DaMonoisotopic mass of the free peptide
AppearanceWhite to off-white powderTypically supplied as a lyophilised solid
Solubility classSoluble in water and polar solventsAlso dissolves in neutral aqueous buffer
Common synonymsMelanotan II, MT-II, MT-2Described as a melanocortin agonist in early literature

Background and Mechanism of Melanotan-2

Melanocytes are the pigment-producing cells of the skin, and they carry melanocortin-1 receptors on their surface. When the receptor is activated, cyclic adenosine monophosphate rises inside the cell and raises the activity of enzymes such as tyrosinase, which increases melanin output. Melanotan-2 binds melanocortin-1 receptors in vitro and in animal models, and this binding is generally described as the basis for the tanning effect. Other receptors account for different effects: melanocortin-4 receptors contribute to appetite and erectile signalling, while melanocortin-3 and melanocortin-5 receptors contribute to energy balance and exocrine function.

Early published reports described melanotan-2 as a tanning agent without sun protection, which means darkening is not the same as protection against ultraviolet radiation. Later studies explored the peptide in erectile dysfunction, hemorrhagic shock, and some skin conditions. No regulator in the United States or Europe has approved it for clinical use. Many products labelled melanotan-2 are sold without approval and their identity and purity are unverified. Its long-term safety in humans remains an open question.

Melanotan-2, also written Melanotan II, is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, and the lactam bridge between the aspartate and lysine side chains constrains the peptide into a ring. This structural change increases receptor affinity and metabolic stability relative to the native hormone. The compound was created in the 1980s as a research tool for studying pigmentation biology.

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Reference notes

=== Major users' response === Beginning around 2000, as the scientific evidence and public concern about trans fat increased, major American users of trans fat began to switch to safer alternatives. The process received a large boost in 2003 when the FDA announced it would require trans fat labeling on packaged food starting in 2006. Packaged food companies then faced the choice of either eliminating trans fat from their products, or having to declare the trans fat on their nutrition label. Lawsuits in the U.S. against trans fat users also encouraged its removal. Major American fast food chains including McDonald's, Burger King, KFC and Wendy's reduced and then removed partially hydrogenated oils (containing artificial trans fats) by 2009. This was a major step toward trans fat removal, as french fries were one of the largest sources of trans fat in the American diet, with a large serving of fries typically having about 6 grams of trans fat until around 2007. Two other events were important in the removal of trans fat. First, in 2013 the FDA announced it planned to completely ban artificial trans fat in the form of partially hydrogenated oil. Second, soon after this, Walmart informed its suppliers they needed to remove trans fat by 2015 if they wanted to continue to sell their products at its stores. As Walmart is the largest brick-and-mortar retailer in the U.S., mainstream food brands had little choice but to comply.

=== 16 August === At least 31 people were killed in RSF shelling on the Abu Shouk camp. The SAF destroyed 4,500 landmines, shells and other munitions recovered near Khartoum in a controlled detonation at the Wadi Seidna garrison as part of cleanup efforts. One person was killed in a grenade attack inside the main hospital of Zalingei.

== History == The term "hydrocolloid" was coined in the 1960s during the development of mucoadhesives, first used to treat mouth ulcers. The term was later adopted for a new dressing type in which a hydrophilic gelable mass was applied to a flexible semipermeable carrier. It was first sold under the brand Granuflex in the United Kingdom in 1982, and then DuoDERM in the United States in 1983. Different products subsequently came to market with slightly varying formulations, designed for specific areas of the body or specific purposes (for example, postoperative dressings). More recently, the term has sometimes been used to describe hydrogel dressings which are fundamentally different to hydrocolloid dressings.

== Pharmacokinetics == When administered orally once a day, mavatrep reached steady-state in healthy volunteers in approximately 14 days. It has a relatively long half-life between 68 and 101 hours in Japanese subjects and between 82 and 130 hours in Caucasian subjects. Mavatrep is largely eliminated non-renally. Mavatrep appears to be metabolized into two primary metabolites which are also eliminated nonrenally.

Wilhelm Röntgen's discovery of X-rays in 1895 led to the use of radiographs to locate bullets in wounded soldiers. Survival rates for gunshot wounds improved among US military personnel during the Korean and Vietnam Wars, due in part to helicopter evacuation, along with improvements in resuscitation and battlefield medicine. Similar improvements were seen in US trauma practices during the Iraq War. Military health care providers who return to civilian practice sometimes disseminate military trauma care practices. One such practice is to transfer major trauma cases to an operating theater as soon as possible, to stop internal bleeding. Within the United States, the survival rate for gunshot wounds has increased, leading to declines in the gun death rate in states that have stable rates of gunshot hospitalizations.

Sources: en.wikipedia.org

Notes from published material

The company was founded by Herbert Hyman (1931–2014) in September 1963, as a coffee service for offices. His wife Mona (whom he married in 1966) and he honeymooned in Sweden where they discovered quality coffee. This sparked the decision to import, roast and sell gourmet coffee in Los Angeles, opening the first Coffee Bean store in 1968 in the Los Angeles neighborhood of Brentwood. Innovations included selling whole beans and touting their country of origin and allowing customers to observe the beans being roasted and then to sample varieties before making a purchase. By the 1970s the firm had expanded to 10 stores in Southern California and had added exotic teas to the menu. In the summer of 1987 an employee brought a blender to a Westwood store where he mixed together ice, coffee extract and chocolate powder, paving the way for the company's signature Ice Blended drinks. With the invention of the Ice Blended, the chain saw a surge in popularity. The drink was a predecessor to the Starbucks Frappuccino. In 1991, when it was first planning to expand into Los Angeles, Starbucks tried to purchase the firm, but Hyman turned them down. The opening of Starbucks stores in Los Angeles unexpectedly helped Coffee Bean's business, by driving curious customers to the area. In 1996, the Hymans sold the Asian franchise rights to Singaporean brothers Victor Sassoon and Sunny Sassoon. The Sassoons quickly expanded the company in the US and internationally, opening the first outlet in Singapore in 1996, and in Malaysia the following year.

== Personal life == Gallrein lives in Shelbyville, Kentucky. He has been married twice. In December 1985, he married Mary E. Stuart. According to court filings, Gallrein filed to divorce his second wife, Heather Gallrein, in 2024 (one month after losing the Kentucky state legislature election). According to court filings, he told her to "get out of his house" and decided to cut her off financially. Gallrein has denied this claim.

A helix has an overall dipole moment due to the aggregate effect of the individual microdipoles from the carbonyl groups of the peptide bond pointing along the helix axis. The effects of this macrodipole are a matter of some controversy. α-helices often occur with the N-terminal end bound by a negatively charged group, sometimes an amino acid side chain such as glutamate or aspartate, or sometimes a phosphate ion. Some regard the helix macrodipole as interacting electrostatically with such groups. Others feel that this is misleading and it is more realistic to say that the hydrogen bond potential of the free NH groups at the N-terminus of an α-helix can be satisfied by hydrogen bonding; this can also be regarded as set of interactions between local microdipoles such as C=O···H−N.

==== Alloys ==== Due to the presence of valence 5f electrons, neptunium and its alloys exhibit a very interesting magnetic behavior, like many other actinides. These can range from the itinerant band-like character characteristic of the transition metals to the local moment behavior typical of scandium, yttrium, and the lanthanides. This stems from 5f-orbital hybridization with the orbitals of the metal ligands, and the fact that the 5f orbital is relativistically destabilized and extends outwards. For example, pure neptunium is paramagnetic, NpAl3 is ferromagnetic, NpGe3 has no magnetic ordering, and NpSn3 may be a heavy fermion material. Investigations are underway regarding alloys of neptunium with uranium, americium, plutonium, zirconium, and iron, so as to recycle long-lived waste isotopes such as neptunium-237 into shorter-lived isotopes more useful as nuclear fuel. One neptunium-based superconductor alloy has been discovered with formula NpPd5Al2. This occurrence in neptunium compounds is somewhat surprising because they often exhibit strong magnetism, which usually destroys superconductivity. The alloy has a tetragonal structure with a superconductivity transition temperature of −268.3 °C (4.9 K).

Sources: en.wikipedia.org

Further detail

However, the commission concluded that an attack on Russian peacekeepers was not "a sufficient condition" to be used for self-defence by Russia and "the fact of the Georgian attack on the Russian peacekeepers’ basis could not be definitely confirmed by the mission." The commission said that Russian peacekeepers had the right to immediate, necessary and proportionate response in case of direct attack on them. However, "doubts remain whether the Russian peacekeepers were attacked in the first place," and the mission "was unable to establish whether, at the time of the alleged attacks on Russian peacekeepers’ bases, the peacekeepers had lost their protection owing to their participation in the hostilities." The commission concluded that "the expulsion of the Georgian forces from South Ossetia, and the defence of South Ossetia as a whole was not a legitimate objective", and "according to international law, the Russian military action taken as a whole was therefore neither necessary nor proportionate to protect Russian peacekeepers in South Ossetia." The commission concluded that Russia did not have the right to justify its actions as "a mere reinforcement and fulfilment of its peacekeeping mission." The commission concluded that the South Ossetian separatists "could not validly invite Russia to support them" militarily and Russian military action could not be justified as intervention in a civil war.

Wound myiasis occurs when fly larvae infest open wounds. It has been a serious complication of war wounds in tropical areas and is sometimes seen in neglected wounds in most parts of the world. Predisposing factors include poor socioeconomic conditions, extremes of age, neglect, mental disability, psychiatric illness, alcoholism, diabetes, and vascular occlusive disease.

Musicians of these decades, especially in jazz and folk music, were influenced by the shadow of nuclear war. Probably the most famous, passionate and influential of all was Bob Dylan, notably in his songs "Masters of War" and "A Hard Rain's a-Gonna Fall" (written just before the Cuban Missile Crisis). In 1965 Barry McGuire's version of P. F. Sloan's apocalyptic "Eve of Destruction" was a number one hit in the United States and elsewhere. Van Cliburn was a pianist who was celebrated with a ticker tape parade after winning a musical competition in the Soviet Union. From 1956 through the late 1970s, the US State Department sent its finest jazz musicians to show off music that appealed to youth, to demonstrate racial harmony at home, and to undergird freedom as jazz was a democratic music form, free flowing and improvised. Jazz tours of the Soviet Union were organized in 1956, and lasted through the 1970s. In addition to jazz, the US State Department also supported the performance of classical music by noteworthy American orchestras and soloists as part of its cultural diplomacy initiatives during the Cold War. During the 1950s, the bass-baritone William Warfield was recruited by the Department of State to perform in six separate European tours which featured productions of the opera Porgy and Bess . In 1961-1962 Howard Hanson's Eastman Philharmonia Orchestra at the Eastman School of Music was selected to represent the nation on an international concert tour which included thirty four cities and sixteen countries in Europe, the Middle East and Russia.

Louisiana governor Jeff Landry requested the deployment of the National Guard for large upcoming events: the Bayou Classic college football event November 27–29, New Year Eve and Day celebrations, and Mardi Gras celebrations in February. The New Orleans police superintendent said, "We are working together and planning their deployment." New Orleans had been the site of the January 1, 2025, terrorism attack in which 14 persons lost their lives and at least 57 persons were injured.

A series of biochemical events propagates and matures the inflammatory response, involving the local vascular system, the immune system, and various cells in the injured tissue. Chronic inflammation is prolonged inflammation that leads to a progressive shift in the type of cells present at the site of inflammation, such as mononuclear cells, and involves simultaneous destruction and healing of the tissue. Inflammation has also been classified as Type 1 and Type 2 based on the type of cytokines and T helper cells (Th1 and Th2) involved.

Sources: en.wikipedia.org

Frequently asked questions

Is melanotan II identical to alpha-melanocyte-stimulating hormone?

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.

How does melanotan II differ from afamelanotide?

Afamelanotide is the linear analogue [Nle4-D-Phe7]-alpha-MSH, sometimes called melanotan I, while melanotan II is cyclic and carries three further substitutions. The two are distinct molecules and are not interchangeable in analytical testing.

Is the receptor binding profile well established?

Binding to the four melanocortin receptor subtypes is well documented in vitro. The relative contribution of each subtype to whole-body effects in humans is far less certain.

What is melanotan II?

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.

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