MC1R is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2026-07-18. Numbers and descriptions here follow the published literature rather than marketing material.
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.
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-2 is handled in the laboratory as a lyophilised powder that dissolves readily in water, dimethyl sulfoxide and dimethylformamide, with limited solubility in ethanol. Stock solutions prepared in an organic solvent often precipitate when diluted into aqueous buffer, so gradual dilution with mixing is standard practice. The peptide carries a tryptophan residue and a histidine residue, both sensitive to oxidation and to alkaline conditions. Working solutions are therefore kept near neutral to slightly acidic pH, protected from light, and consumed within the same working session whenever that is practical.
Solid peptide kept dry at minus twenty degrees Celsius, shielded from light and moisture, is generally considered stable for extended periods. Solutions are divided into single-use aliquots and held at minus twenty or minus eighty degrees Celsius, because repeated freeze-thaw cycles promote aggregation and loss of material to container surfaces. Hydrolysis of the backbone and oxidation of tryptophan are the principal degradation routes in aqueous solution, and both accelerate at ambient temperature. Hygroscopic uptake after a vial is opened can also shift the actual mass weighed, which affects any concentration calculated from it.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analogue of alpha-melanocyte-stimulating hormone |
| Common synonyms | MT-II; melanotan 2 | No internationally accepted non-proprietary name |
| Typical presentation | Lyophilised powder in a sealed vial | Often supplied alongside a separate diluent |
| Regulatory status | Unapproved therapeutic substance | Customs seizure reported in several jurisdictions |
| Reported route in use | Subcutaneous injection | Self-administered outside clinical settings |
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.
Scientific discussion of Melanotan-2 spans pharmacology, dermatology, and public-health literature. Laboratory studies examine its receptor binding and cellular effects, while clinical reports describe outcomes observed after unregulated use. These two bodies of work differ in rigour and intent. Peer-reviewed trials of the compound as a medicine are limited, so much of the available information comes from case reports and surveillance data. Authors frequently note the gap between experimental findings and real-world use.
Reported observations after unregulated use include shifts in skin pigmentation and, in some accounts, unintended changes to moles and other lesions. Whether these outcomes are causally linked to the compound, and how often they occur, remain open questions because controlled data are scarce. The absence of standardised dosing and verified product purity complicates interpretation. Researchers have called for better surveillance and analytical characterisation of samples obtained outside regulated channels. Conclusions drawn from anecdotal evidence should be treated as provisional.
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.
== Synthesis == Immunoliposomes are created when antibodies are conjugated to liposomes. One way to do this is through covalent bonds between the antibody (or its fragment) and the lipid. Another way is through chemical modification of antibodies so they have a higher affinity for the liposome. "In general, the conjugation methodology is based on three main reactions; a reaction between activated carboxyl groups and amino groups which yields an amide bond, a reaction between pyridyl dithiols and thiols which yields disulfide bonds, and a reaction between maleimide derivatives and thiols, which yields thioether bonds."
=== Early history === 1935 – Midwest Consultants was founded in St Louis by brothers Aaron Fischer and Bernard Fischlowitz, who hired chemical engineer Daniel Broida. 1946 – Sigma was formed from Midwest Consultants and manufactured just adenosine triphosphate. They were the first to manufacture pure ATP. 1972 – Sigma's IPO 1951 – Aldrich founded in Milwaukee by Alfred Bader and Jack Eisendrath and manufactured just 1-methyl-3-nitro-1-nitrosoguanidine. 1966 – Aldrich's IPO 1972 – Subsidiary Aldrich-Boranes launched to manufacture hydroboration products 1975 – Merger of Sigma Chemical and Aldrich Chemical to created Sigma-Aldrich. Their first year earned $43 million in sales. 1999 – Sigma-Aldrich reaches $1 billion in sales 2005 – Announced membership in The RNAi Consortium 2014 – Merck KGaA announced that it would purchase Sigma-Aldrich for approx. $17 billion (€13.1 billion). November 3, 2014 – Sigma-Aldrich filed a definitive proxy statement with the U.S. Securities and Exchange Commission to hold a special investors meeting regarding approval for the sale to Merck KGaA.
These synthetic opioids have increased length and depth of satiating any opiate cravings and generate very strong analgesic effects due to their long metabolic half-life and strong receptor affinity at the mu-opioid receptor sites. Therefore, they impart much of the satiating and anti-addictive effects of methadone by suppressing drug cravings. It was only in 1947 that the drug was given the generic name "methadone" by the Council on Pharmacy and Chemistry of the American Medical Association. Since the patent rights of the I.G. Farbenkonzern and Farbwerke Hoechst were no longer protected, each pharmaceutical company interested in the formula could buy the rights for the commercial production of methadone for just one dollar (MOLL 1990). Methadone was introduced into the United States in 1947 by Eli Lilly and Company as an analgesic under the trade name Dolophine. An urban myth later arose that Nazi leader Adolf Hitler ordered the manufacture of methadone or that the brand name 'Dolophine' was named after him, probably based on the similarity of "doloph" with "Adolph". (The pejorative term "adolphine" would appear in the early 1970s.) However, the name "Dolophine" was a contraction of "Dolo" from the Latin word dolor (pain), and finis, the Latin word for "end". Therefore, Dolophine literally means "pain end". Methadone was studied as a treatment for opioid addiction at the Addiction Research Center of the Narcotics Farm in Lexington, Kentucky in the 1950s, and by Rockefeller University physicians Robert Dole and Marie Nyswander in the 1960s in New York City.
Sources: en.wikipedia.org
== Function == This gene is a member of the NAD(P)H dehydrogenase (quinone) family and encodes a cytoplasmic 2-electron reductase. This FAD-binding protein forms homodimers and reduces quinones to hydroquinones. This enzyme facilitates the two electron reduction of quinone to hydroquinone. NQO1-mediated two electron reduction of quinone to hydroquinone thereby indirectly prevents the one electron reduction of quinone to the semiquinone free radical. The ubiquitin-independent p53 degradation pathway is regulated by NQO1. NQO1 stabilizes p53, protecting it from degradation. Individuals with decreased NQO1 expression/activity have reduced p53 stability, which may lead to resistance to drugs such as chemotherapeutics.
== Autophosphorylation == Autophosphorylation is the process in which a kinase attaches a phosphate group to itself. When CaMKII autophosphorylates, it becomes persistently active. Phosphorylation of the Threonine 286 site allows for the activation of the catalytic domain. Autophosphorylation is enhanced by the structure of the holoenzyme because it is present in two stacked rings. The close proximity of these adjacent rings increases the probability of phosphorylation of neighboring CaMKII enzymes, furthering autophosphorylation. A mechanism that promotes autophosphorylation features inhibition of the PP1 (protein phosphatase I). This enables CaMKII to be constantly active by increasing the likelihood of autophosphorylation.
Temperature dependence: LED performance largely depends on the ambient temperature of the operating environment – or thermal management properties. Overdriving an LED in high ambient temperatures may result in overheating the LED package, eventually leading to device failure. An adequate heat sink is needed to maintain long life. This is especially important in automotive, medical, and military uses where devices must operate over a wide range of temperatures, and require low failure rates.
Sources: en.wikipedia.org
In solid phase peptide synthesis, a linker is a molecule that connects the solid phase (a beaded resin support) to the growing peptide chain. The linker is often permanently attached to the solid phase, but carries a transient covalent bond to the peptide (typically its C-terminus) that can be cleaved after completion of the synthesis to release the peptide. Cleavage can take place under various conditions depending on the linker type and result in different C-terminal functionalities of the released peptide, e.g. amides, carboxylic acids, esters, lactams, etc. Linkers that do not attach via the C-terminus do also exist.
=== Tyrannosaurus imperator and Tyrannosaurus regina === In a 2022 study, Gregory S. Paul and colleagues argued that Tyrannosaurus rex, as traditionally understood, actually represents three species: the type species Tyrannosaurus rex, and two previously unrecognized species: T. imperator (meaning "tyrant lizard emperor") and T. regina (meaning "tyrant lizard queen"). The holotype of the former (T. imperator) is the Sue specimen, and the holotype of the latter (T. regina) is Wankel rex. The division into multiple species was primarily based on the high degree of variation in the proportions and robusticity of the femur (and other skeletal elements) across T. rex specimens. Presumed robust and gracile morphotypes and the number of small incisiform teeth in the dentary were also used as a line of evidence. Paul and colleagues categorized the species as follows: T. rex demonstrates robust anatomy, a moderate ratio of femur length vs circumference, and the possession of a singular slender incisiform dentary tooth, T. imperator is robust with a small femur length to circumference ratio and two of the slender teeth, and T. regina is more gracile with a high femur ratio and one of the slender teeth. However, several leading paleontologists, including Stephen Brusatte, Thomas Carr, Thomas Holtz, David Hone, Jingmai O'Connor, and Lindsay Zanno, criticized the study or expressed skepticism of its conclusions.
Escitalopram discontinuation, particularly abruptly, may cause certain withdrawal symptoms such as "electric shock" sensations, colloquially called "brain shivers" or "brain zaps" by those affected. Frequent symptoms in one study were dizziness (44%), muscle tension (44%), chills (44%), confusion or trouble concentrating (40%), amnesia (28%), and crying (28%). Very slow tapering is recommended. There have been spontaneous reports of discontinuation of escitalopram and other SSRIs and SNRIs, especially when abrupt, leading to dysphoric mood, irritability, agitation, anxiety, headache, lethargy, emotional lability, insomnia, and hypomania. Other symptoms such as panic attacks, hostility, aggression, impulsivity, akathisia (psychomotor restlessness), mania, worsening of depression, and suicidal ideation can emerge when the dose is adjusted down.
== Mechanism of action == Tedizolid phosphate (TR-701) is a prodrug activated by plasma or intestinal phosphatases to tedizolid (TR-700) following administration of the drug either orally or intravenously. Once activated, tedizolid exerts its bacteriostatic microbial activity through inhibition of protein synthesis by binding to the 50S ribosomal subunit (on the acceptor site) of the bacteria.
Sources: en.wikipedia.org
No. No major regulatory agency has granted a marketing authorisation for melanotan II as a medicine. Products sold under this name are generally presented as laboratory reagents and are not subject to the batch-release testing applied to approved drugs.
It was developed in the 1980s by researchers investigating analogues of alpha-melanocyte-stimulating hormone for pigmentation and related endpoints. Early work included small human studies during the 1990s. Development did not progress to licensing, and the compound remained a research and grey-market item.
Peptides are prone to truncation, oxidation and aggregation during synthesis and handling. Without independent testing, a buyer cannot confirm the identity or the content of a vial. Analytical surveys of unapproved peptide products have repeatedly found discrepancies between label claims and measured composition.
Purity is normally stated as an area percentage from high-performance liquid chromatography, for example ninety-five or ninety-eight percent. That figure describes the proportion of ultraviolet-absorbing material eluting as the main peak. It says nothing about water content, counterions, residual solvents or mass fraction of the peptide itself.