A practical reference on MC1R: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-01-01. Anything still debated is marked as such rather than presented as settled.
Melanotan-2 is frequently confused with afamelanotide, a linear analogue authorised in the European Union for erythropoietic protoporphyria. The two compounds differ in chain length, ring structure and receptor selectivity, so findings for one cannot be transferred directly to the other. Published controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports. Questions about effect size, dose-response behaviour and long-term safety therefore remain unresolved.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
The peptide acts as a non-selective agonist at melanocortin receptors, showing affinity for MC1R, MC3R, MC4R and MC5R. Activation of MC1R on melanocytes drives the conversion of tyrosine into melanin and shifts production toward the darker eumelanin form. MC4R signalling in the central nervous system is linked to appetite and energy balance, which helps explain why reduced food intake appeared in early human studies. Effects on MC4R and on vascular tone also account for the erectile responses recorded as unexpected findings in those same trials.
The compound emerged from research programs in the 1980s that examined analogues of alpha-melanocyte-stimulating hormone for pigmentation and photoprotection. Investigators modified the native sequence to extend activity duration and potency. A related analogue, afamelanotide, was developed within the same broad line of inquiry and eventually gained approval in certain jurisdictions for a rare light-sensitivity condition. Melanotan-2 itself did not progress through the same regulatory route and has no approved therapeutic indication.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Alpha-MSH analogue with a lactam ring |
| Molecular formula | C50H69N15O9 | Commonly cited value for the neutral peptide |
| Molecular weight | 1024.18 g/mol | Calculated for the free molecule |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water, DMSO and ethanol | Dissolution in pure water is often slow |
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.
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.
=== Structure === Like most Platinum-based anti cancer drugs, nedaplatin is a square planar platinum(II) complex. It contains two leaving groups in the form of the glycolate and two mutually cis amines.
Mads Krogsgaard Thomsen (born December 27, 1960) is a Danish businessman who is the CEO of the Novo Nordisk Foundation and former executive vice president of research & development (R&D), head of R&D and chief scientific officer at the pharmaceutical company Novo Nordisk.
Iron-deficiency anemia is confirmed by tests that include serum ferritin, serum iron level, serum transferrin, and total iron binding capacity. A low serum ferritin is most commonly found. However, serum ferritin can be elevated by any chronic inflammation and thus is not consistently decreased in iron-deficiency anemia. Serum iron levels may be measured, but serum iron concentration is not as reliable as the measurement of both serum iron and serum iron-binding protein levels. The percentage of iron saturation (or transferrin saturation index or percent) can be measured by dividing the level of serum iron by total iron binding capacity and is a value that can help to confirm the diagnosis of iron-deficiency anemia; however, other conditions must also be considered, including other types of anemia. Another finding that can be used is the level of red blood cell distribution width. During haemoglobin synthesis, trace amounts of zinc will be incorporated into protoporphyrin in the place of iron which is lacking. Protoporphyrin can be separated from its zinc moiety and measured as free erythrocyte protoporphyrin, providing an indirect measurement of the zinc-protoporphyrin complex. The level of free erythrocyte protoporphyrin is expressed in either μg/dl of whole blood or μg/dl of red blood cells. An iron insufficiency in the bone marrow can be detected very early by a rise in free erythrocyte protoporphyrin. Further testing may be necessary to differentiate iron-deficiency anemia from other disorders, such as thalassemia minor.
The Soviets designed their first human space capsule using the same spacecraft bus as their Zenit spy satellite, forcing them to keep the details and true appearance secret until after the Vostok program was over. The craft consisted of a spherical descent module with a mass of 2.46 tonnes (5,400 lb) and a diameter of 2.3 meters (7.5 ft), with a cylindrical inner cabin housing the cosmonaut, instruments, and escape system; and a biconic instrument module with a mass of 2.27 tonnes (5,000 lb), 2.25 meters (7.4 ft) long and 2.43 meters (8.0 ft) in diameter, containing the engine system and propellant. After reentry, the cosmonaut would eject at about 7,000 meters (23,000 ft) over the USSR and descend via parachute, while the capsule would land separately, because the descent module made an extremely rough landing that could have left a cosmonaut seriously injured. The "Vostok spaceship" was first displayed at the July 1961 Tushino air show, mounted on its launch vehicle's third stage, with the nose cone in place concealing the spherical capsule. A tail section with eight fins was added in an apparent attempt to confuse western observers. This also appeared on official commemorative stamps and a documentary. The Soviets finally revealed the true appearance of their Vostok capsule at the April 1965 Moscow Economic Exhibition.
Sources: en.wikipedia.org
This variant is sometimes referred to as "cooking the absinthe" or "the flaming green fairy". The origin of this burning ritual may borrow from a coffee and brandy drink that was served at Café Brûlot, in which a sugar cube soaked in brandy was set aflame. Most experienced absintheurs do not recommend the Bohemian Method and consider it a modern gimmick, as it can destroy the absinthe flavour and present a fire hazard due to the unusually high alcohol content present in absinthe.
== Interactions == Extracellular interaction with a tripartite receptor composed of gp130, WSX1, and CNTFR, as well as interaction with the formyl peptide receptor 2 (formylpeptide-like-1 receptor) have been published. Intracellular interaction with BAX, tBID, IGFBP3, and TRIM11 may also be required for the effects of humanin.
== External links == Media related to Eflornithine at Wikimedia Commons Clinical trial number NCT02395666 for "Preventative Trial of Difluoromethylornithine (DFMO) in High Risk Patients With Neuroblastoma That is in Remission" at ClinicalTrials.gov Clinical trial number NCT02679144 for "Neuroblastoma Maintenance Therapy Trial (NMTT)" at ClinicalTrials.gov
Kevin Darnell Hart (born July 6, 1979) is an American comedian and actor. After winning several stand-up comedy competitions, Hart had his first breakthrough when Judd Apatow cast him in a recurring role on the TV series Undeclared (2001). Hart's comedic reputation continued to grow with the release of his first stand-up album I'm a Grown Little Man (2009). He has since released four more comedy albums: Seriously Funny (2010), Laugh at My Pain (2011), Let Me Explain (2013), and What Now? (2016). As an actor, Hart has had roles in films such as Paper Soldiers (2002), Scary Movie 3 (2003), Soul Plane (2004), In the Mix (2005), Little Fockers (2010), Think Like a Man (2012), Grudge Match (2013), Ride Along (2014), About Last Night (2014), Get Hard (2015), Central Intelligence (2016), The Secret Life of Pets film franchise (2016–2019), Ride Along 2 (2016), Captain Underpants: The First Epic Movie (2017), the Jumanji film franchise (2017–present), and Night School (2018). He also created and starred as a fictionalized version of himself in Real Husbands of Hollywood (2013–2016). In 2017, he launched the Laugh Out Loud Network, a subscription video streaming service in partnership with Lionsgate. Hart has received numerous accolades including the Mark Twain Prize for American Humor in 2024, and nominations for two Grammy Awards and four Primetime Emmy Awards. In 2015, Time magazine named him on its annual list of the 100 most influential people in the world.
The table shows that this partial pressure is not achieved until the temperature is nearly 800 °C. For the outgassing of CO2 from calcium carbonate to happen at an economically useful rate, the equilibrium pressure must significantly exceed the ambient pressure of CO2. And for it to happen rapidly, the equilibrium pressure must exceed total atmospheric pressure of 101 kPa, which happens at 898 °C.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.
No national medicines agency has approved melanotan-2 for clinical use. Afamelanotide, a related but distinct peptide, holds a marketing authorisation in the European Union for a rare photosensitivity disorder. Melanotan-2 itself is handled as a laboratory chemical.
Its broad activity across melanocortin receptors makes it a tool for probing pigmentation, appetite and vascular signalling. Early trials recorded skin darkening and other effects that were not the original focus of the work. Those observations generated hypotheses that later studies have examined.
No. Melanotan-2 is manufactured synthetically. The naturally occurring peptide in the same family is alpha-melanocyte-stimulating hormone, which the body produces as part of normal endocrine and neural signalling.