If you have been reading about melanocortin receptor and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-03-29. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
The compound was developed in the late 1980s and 1990s by academic researchers investigating photoprotection. The rationale held that stimulating melanin production might reduce ultraviolet damage to skin and lower skin cancer risk. Early work examined receptor binding, pigment response, and short-term tolerability in small studies. That program did not produce an approved drug, and formal development stalled after early-phase trials. Whether induced pigmentation confers meaningful photoprotection remains an open question.
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.
| Property | Value | Notes |
|---|---|---|
| Compound class | Synthetic cyclic heptapeptide | Alpha-MSH analogue containing a D-phenylalanine residue |
| Molecular formula | C50H69N15O9 | Average molecular mass approximately 1024.2 g/mol |
| Appearance | White to off-white lyophilised powder | Normally supplied as a freeze-dried solid in a sealed vial |
| Solubility | Freely soluble in water and polar solvents | Dissolves readily in aqueous buffers and in alcohol-water mixtures |
| Receptor targets | MC1R, MC3R, MC4R, MC5R | Acts as a non-selective melanocortin receptor agonist |
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.
The General dumps the cargo module Archer is hiding in to gain speed and leaves the AI facility's science team behind to die. As Archer progresses through the facility, he learns that the Mainframe's primary battle is with a major Xenome infestation that the humans brought onto the moon. Fighting both attack drones and Xenomes alike, Archer makes his way through the facility. Despite the Mainframe's best efforts, Archer manages to destroy most of the "kata-space anchors" that keep the moon from falling to the planet below. Archer survives the destruction of the anchors, but is stranded on the falling moon. Archer eventually finds the Mainframe and they form an uneasy alliance: the Mainframe will provide an aerial drone for Major Archer to escape in, but only if he takes the Mainframe's core with him. Major Archer agrees, and they battle through hordes of Xenome forces with the help of the Mainframe's attack drones. Major Archer and the AI successfully reach and board the aerial drone, but fail to navigate through an asteroid field on their way into kata-space and crash land on a desert planet called Icnus, encountering and fighting rogue Gunmen. Icnus turns out to be the location of the General's main Xenome facility. Archer battles his way through the facility with the help of the Mainframe, accidentally causing a captured Worm Xenome, one of the most dangerous Xenomes in existence, to break loose. The Mainframe helps Archer to the General's location and they engage in a firefight, where the AI's newly constructed Super Drone defeats the General's Kata-Drone.
== Effects upon US public opinion == One effect of the dispute in the US was to awaken the public's interest in the issue. This interest was not wholly unsympathetic to the EU. In 1989, for example, the Consumer Federation of America and the Center for Science in the Public Interest both pressed for an adoption of a ban within the US similar to that within the EU. In a study done in 2002, 85% of respondents wanted mandatory labeling on beef produced with growth hormones.
=== Butterfly === An original incarnation of Psylocke named O-Chiyo Braddock appears in 5 Ronin. This version is the English-Japanese orphan daughter of a local Japanese woman who died when she was a baby and an English expat trader who committed suicide when she was a child after his business failed. After being forced into the yoshiwara to survive, O-Chiyo grows up to become the top-ranked prostitute, codenamed "Butterfly", in a high-end brothel. She later crosses paths with a Ronin called the Wolverine, who becomes her regular customer.
== Prognosis == Generally, long-term prognosis is helpful to survival of initial exposure to nitrogen dioxide. Some cases of nitrogen dioxide poisoning resolves with no observable symptoms and patient may be determined by pulmonary function testing. If chronic exposure causes lung damage, it could take several days or months for the pulmonary function to improve. Meanwhile, permanent mild dysfunction may result from bronchiolitis obliterans and could manifest as abnormal flow at 50 to 70 percent of vital capacity. It may also manifest as mild hyperinflammation, airway obstruction and in that case, patient may be subject to steroid treatment to treat deconditioning. Complications from prolong exposure includes bronchiolitis obliterans and other secondary infections such as pneumonia due to injuries on the mucous membrane from pulmonary edema and inhibition of immune system by nitrogen dioxide. Nitrogen dioxide inhalation can result in short and long-term morbidity or death depending on the extent of exposure and inhaled concentration and the exposure time. Illness resulting from acute exposure is usually not fatal although some exposure may cause bronchiolitis obliterans, pulmonary edema as well as rapid asphyxiation. If the concentration of exposure is excessively high, the gas may displace oxygen resulting in fatal asphyxiation. Generally, patients and workers should be educated by medical personnel on how to identify the signs and symptoms of Nitrogen dioxide poisoning.
Sources: en.wikipedia.org
In a randomized, controlled trial 12 healthy volunteers ingested 200 mL of either grapefruit juice or water three times daily for five days. On the fourth day 10 mg of oxycodone hydrochloride were administered orally. Analgesic and behavioral effects were reported for 12 hours and plasma samples were analyzed for oxycodone metabolites for 48 hours. Grapefruit juice increased the mean area under the oxycodone concentration-time curve (AUC(0-∞)) by 1.7 fold, the peak plasma concentration by 1.5-fold and the half-life of oxycodone by 1.2-fold as compared to water. The metabolite-to-parent ratios of noroxycodone and noroxymorphone decreased by 44% and 45% respectively. Oxymorphone AUC(0-∞) increased by 1.6-fold but the metabolite-to-parent ratio remained unchanged. Quetiapine (Seroquel) Repaglinide (Prandin) Sirolimus (Rapamycin, Rapamune) Tamoxifen (Nolvadex): Tamoxifen is metabolized by CYP2D6 into its active metabolite 4-hydroxytamoxifen. Grapefruit juice may potentially reduce the effectiveness of tamoxifen. Trazodone (Desyrel): Little or no interaction with grapefruit juice. Verapamil (Calan SR, Covera HS, Isoptin SR, Verelan): atrioventricular conduction disorders. Warfarin (coumadin) Zolpidem (Ambien): Little or no interaction with grapefruit juice
=== Homomers === An assemblage of multiple copies of a particular polypeptide chain can be described as a homomer, multimer or oligomer. Hundreds of proteins have been identified as being assembled into homomers in human cells. Homomer formation may be driven by interaction between nascent polypeptide chains as they are translated from mRNA by nearby adjacent ribosomes.
== Advantages == A major advantage of the SELDI process is the chromatographic separation step. While liquid chromatography-mass spectrometry (LC-MS) is based on the elution of analytes in the separated sample, separation in SELDI is based on retention. Any sample components that interfere with analytical measurements, such as salts, detergents, and buffers, are washed away before analysis with mass spectrometry. Only the analytes that are bound to the surface are analyzed, reducing the overall complexity of the sample. As a result, there is an increased probability of detecting analytes that are present in lower concentrations. Because of the initial separation step, protein profiles can be obtained from samples of as few as 25-50 cells. In biological applications, SELDI-TOF-MS has a major advantage in that the technique does not require the use of radioactive isotopes. Furthermore, an assay can be sampled at multiple time points during an experiment. Additionally, in proteomics, the biomarker discovery, identification, and validation steps can all be done on the SELDI surface.
On 24 November 2011, three trucks containing 26 bodies were found in an avenue at Guadalajara, Jalisco. All of them were male corpses. At around 7:00 pm, the Guadalajara police received numerous anonymous calls from civilians reporting that "several vehicles with more than 10 bodies had been abandoned" in a major avenue. Upon the arrival of the police forces, they found a green Dodge Caravan in the middle lane of the highway, along with a Nissan Caravan just 66 feet (20 meters) away; on the farthest right lane was a white van. Reports state that Los Zetas and the Milenio Cartel are responsible for the massacre of these twenty-six alleged Sinaloa Cartel members. In addition, in November 2011, three men from the Milenio Cartel were arrested and linked to the massacre of the twenty-six people. The authorities concluded that only six of the twenty-six that were killed had criminal records, and another ten of those dead were reported as disappeared by their family members. Among those killed were small-business entrepreneurs; a cook; a mechanic; a dentist; a truck driver; and a house painter, among others. According to the testimonies of several family members, a group of heavily armed men abducted several people by force. One of the witnesses said that some teenagers were "drinking soda in front of a store when armed men" in two trucks abducted them. The family of one of the kidnapped victims claimed that their loved one was "a teenager without vices or problems", and that the versions of him being part of a cartel are unjust and false.
== Applications == Gold fingerprinting characterizes a gold sample or gold-containing item by analyzing its trace elements, identifying the sample by its mineralizing event and linking it to a specific mine or bullion source. Elements that are measured above detection limits can be used for gold fingerprinting and geochemical characterization. For this technique to be effective in identifying the origins of gold, a database of fingerprinted samples from mines and bullion sources is required. This technique has been used to assert claims over stolen or relocated gold, even in instances where it has been salted—deliberately blended with gold from disparate origins. Beyond this, gold fingerprinting serves as a tool in identifying the often obscure provenance of gold artifacts.
Sources: en.wikipedia.org
=== India === In the 1990s, India stopped its research in cold fusion at the Bhabha Atomic Research Centre because of the lack of consensus among mainstream scientists and the US denunciation of the research. Yet, in 2008, the National Institute of Advanced Studies recommended that the Indian government revive this research. Projects were commenced at Chennai's Indian Institute of Technology, the Bhabha Atomic Research Centre and the Indira Gandhi Centre for Atomic Research. However, there is still skepticism among scientists and, for all practical purposes, research has stalled since the 1990s. A special section in the Indian multidisciplinary journal Current Science published 33 cold fusion papers in 2015 by major cold fusion researchers including several Indian researchers. A Hyderabad-based startup, Hylenr Technologies, showcased the amplification of electrical energy into significantly more heat energy using the a LENR system. The startup is being guided by a former DRDO scientist, Padma Shri awardee, Dr. Prahlada Ramarao.
The updated language also clarified that the non-exhaustive list of exempted materials was illustrative in nature, inferring that unlisted materials not yet invented or in wide use at the time of its passage would be prohibited from being subject to sanctions or other regulation under both acts.
The process of acute inflammation is initiated by resident immune cells already present in the involved tissue, mainly resident macrophages, dendritic cells, histiocytes, Kupffer cells and mast cells. These cells possess surface receptors known as pattern recognition receptors (PRRs), which recognize (i.e., bind) two subclasses of molecules: pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). PAMPs are compounds that are associated with various pathogens, but which are distinguishable from host molecules. DAMPs are compounds that are associated with host-related injury and cell damage. At the onset of an infection, burn, or other injuries, these cells undergo activation (one of the PRRs recognize a PAMP or DAMP) and release inflammatory mediators responsible for the clinical signs of inflammation. Vasodilation and its resulting increased blood flow causes the redness (rubor) and increased heat (calor). Increased permeability of the blood vessels results in an exudation (leakage) of plasma proteins and fluid into the tissue (edema), which manifests itself as swelling (tumor). Some of the released mediators such as bradykinin increase the sensitivity to pain (hyperalgesia, dolor). The mediator molecules also alter the blood vessels to permit the migration of leukocytes, mainly neutrophils and macrophages, to flow out of the blood vessels (extravasation) and into the tissue. The neutrophils migrate along a chemotactic gradient created by the local cells to reach the site of injury.
=== South Asia === Commentator Ehsan Ahrari, writer Bruce Riedel, political commentator Sanjaya Baru and Princeton University academic Zia Mian have used the term "cold war" since 2002 to refer to long-term tensions between India and Pakistan, which were part of British India until its partition in 1947.
Sources: en.wikipedia.org
No. It is a laboratory-made peptide, while the natural hormone is alpha-melanocyte-stimulating hormone, a longer peptide produced by the pituitary gland and by skin cells. Melanotan-2 mimics only a short active region of that hormone and contains non-natural residues such as D-phenylalanine.
No approved regulatory indication exists in major markets. An approval exists for a different peptide, afamelanotide, which is used for a rare photosensitivity disorder called erythropoietic protoporphyria. Melanotan-2 itself remains a research compound with no cleared clinical role.
Melanocortin-1 receptors on melanocytes are the receptor most closely linked to pigment production. The peptide is not selective, however, and also activates melanocortin-3, melanocortin-4, and melanocortin-5 receptors. That lack of selectivity is the usual explanation offered for both its range of observed effects and its off-target effects.
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.