This is a working overview of alpha-MSH, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-05-16 and is reviewed periodically as new material appears.
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.
Routine characterisation relies on reversed-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres, using a C18 column and a water-acetonitrile gradient containing trifluoroacetic acid. Electrospray ionisation mass spectrometry confirms the expected molecular mass and can reveal truncated or oxidised by-products that co-elute poorly. Sequence and stereochemistry require additional work, such as peptide mapping or amino acid analysis, because a chromatographic purity figure alone does not distinguish a diastereomer from the target peptide. Independent testing of research-grade material frequently shows measured content below the stated label, so a certificate of analysis is best read together with the method that produced it.
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.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C50H69N15O9 | Cyclic heptapeptide, C-terminally amidated |
| Approximate molecular mass | 1024 Da | Monoisotopic mass of the free peptide |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility class | Soluble in water and polar solvents | Also dissolves in neutral aqueous buffer |
| Common synonyms | Melanotan II, MT-II, MT-2 | Described as a melanocortin agonist in early literature |
Receptor binding at MC1R on melanocytes raises intracellular cyclic AMP and increases expression of tyrosinase and related enzymes. The downstream result is greater synthesis of eumelanin, the dark pigment, without ultraviolet exposure acting as the trigger. The compound is not selective, however, and also engages MC3R, MC4R and MC5R, which are expressed in the central nervous system and elsewhere. That lack of selectivity is the explanation usually offered for effects reported outside pigmentation, including appetite suppression and nausea. Selectivity remains a central theme in comparative studies of related peptides.
Human data remain limited and mostly short-term. Reports describe small trials and observational accounts rather than large controlled studies, so questions about dose-response relationships and long-term effects on melanocytes stay open. Whether repeated exposure alters naevus behaviour is not settled in the published record. Researchers also note that self-administered use outside clinical settings makes actual exposure difficult to quantify. Statements about efficacy and safety should therefore be read as preliminary rather than established.
Melanotan-2 appears on the World Anti-Doping Agency prohibited list within the peptide hormone class, and several national regulators treat it as an unapproved prescription substance. Some countries restrict importation or sale for personal use. Because the compound is widely traded as a research chemical, the practical legal picture differs between jurisdictions and shifts over time. Human safety data covering long periods are limited, and whether repeated pigmentation changes carry any lasting risk to melanocytes remains an open question.
Freeze-dried melanotan-2 is normally kept as a desiccated powder at minus twenty degrees Celsius or lower, shielded from light and moisture. Peptides of this size degrade through hydrolysis, oxidation and deamidation, and each pathway accelerates as temperature and water activity rise. Repeated freeze-thaw cycles promote aggregation and loss of material, so aliquoting a stock solution before freezing is standard laboratory practice. Once dissolved, the solution is markedly less stable than the powder. In laboratory work, solutions are generally refrigerated and used within days rather than kept for months.
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.
== Assessment and treatment == Assessment can be difficult because much of the damage is often internal and not visible. The patient is thoroughly examined. X-ray and CT scanning may be used to identify the type and location of potentially lethal injuries. Sometimes before an X-ray is performed on a person with penetrating trauma from a projectile, a paper clip is taped over entry and exit wounds to show their location on the film. The patient is given intravenous fluids to replace lost blood. Surgery may be required; impaled objects are secured into place so that they do not move and cause further injury, and they are removed in an operating room. If the location of the injury is not obvious, a surgical operation called an exploratory laparotomy may be required to look for internal damage to the organs in the abdomen. Foreign bodies such as bullets may be removed, but they may also be left in place if the surgery necessary to get them out would cause more damage than would leaving them. Wounds are debrided to remove tissue that cannot survive and other material that presents risk for infection. Negative pressure wound therapy is no more effective in preventing wound infection than standard care when used on open traumatic wounds.
== Prevention == A primary means of limiting risk from aflatoxins in the food supply is food hygiene in the commercial commodity supply chain, such as rejecting moldy grain for use in food processing plants and testing of batches of ingredients for aflatoxin levels before adding them to the mix. Regulatory agencies such as the FDA set limits on acceptable levels. Grain drying itself, which is necessary for viable combine harvesting in many regions, assists in this effort by preventing stored grain from being too damp in the first place. The use of nixtamalization, the processing of maize or other grains by soaking and cooking in alkali solution, greatly reduces aflatoxin concentrations. There is very limited evidence to show that agricultural and nutritional education can reduce exposure to aflatoxin in low to middle-income countries.
=== Subtypes === There are several subtypes of catatonia recognized: stuporous catatonia, excited catatonia, malignant catatonia, and periodic catatonia. Subtypes are defined by the group of symptoms and associated features that a person is experiencing or displaying. Although catatonia can be divided into subtypes, its presentation is often dynamic, and the same individual may exhibit different subtypes at different times. Stuporous catatonia is characterized by immobility, mutism, and a lack of response to the world around them. They may appear frozen in one position for long periods of time unable to eat, drink, or speak. Excited catatonia is characterized by odd mannerisms and gestures, purposeless or inappropriate actions, excessive motor activity, restlessness, stereotypy, impulsivity, agitation, and combativeness. Patients suffering from excited catatonia may have speech and actions that are repetitive or mimic another person's. This state is often characterized by hyperactivity, and the patient may have delusions and hallucinations. Malignant catatonia is characterized by fever, dramatic and rapid changes in blood pressure, increased heart rate and respiratory rate, and excessive sweating. This condition is life-threatening, and the patient's laboratory tests may come back abnormal. Periodic catatonia is characterized by a person having recurrent episodes of catatonia. Individuals will experience multiple episodes over time, with no signs of catatonia between episodes.
He added that Afghanistan had taken serious measures to ensure its territory was not used against Pakistan and said its military actions were defensive. Pakistan's Defence Minister, Khawaja Asif, implicitly confirmed that indirect talks with the Afghan Taliban were taking place through third-party mediators, although he described the process as unstructured and informal. He added that if the efforts failed to secure peace, Pakistan could return to its previous approach and escalate military operations in parts of Afghanistan. Pakistani military claimed to have killed 10 TTP militants in an operation in Khyber District and three more in Bannu. On 31 March, Taliban and Pakistani forces clashed in Dangam District of Kunar Province. On 1 April, 4 police personnel and 5 civilians were injured in an improvised explosive device (IED) blast carried out by Pakistani Taliban in Pakistan's Lakki Marwat district. On 2 April, Pakistani officials said that they foiled an infiltration attempt along the Afghanistan–Pakistan border, killing eight militants and seizing a large quantity of weapons and ammunition. That same day, Taliban and Pakistani officials confirmed that they were holding preliminary talks mediated by China in Ürümqi. Pakistani officials described the talks as working-level and said that they had sent their mid-level delegation to take part in the talks.
Lying in the perineum (space between the vulva and anus) and within the superficial perineal pouch is the root of the clitoris, which consists of the posterior ends of the clitoris, the crura and the bulbs of vestibule. The crura ("legs") are the parts of the corpora cavernosa extending from the clitoral body and form an upside-down "V" shape. Each crus (singular form of crura) is attached to the corresponding ischial ramus – extensions of the corpora beneath the descending pubic rami. Concealed behind the labia minora, the crura end with attachment at or just below the middle of the pubic arch. Associated are the urethral sponge, perineal sponge, a network of nerves and blood vessels, the suspensory ligament of the clitoris, muscles and the pelvic floor. The vestibular bulbs are more closely related to the clitoris than the vestibule because of the similarity of the trabecular and erectile tissue within the clitoris and its bulbs, and the absence of trabecular tissue in other parts of the vulva, with the erectile tissue's trabecular nature allowing engorgement and expansion during sexual arousal. The vestibular bulbs are typically described as lying close to the crura on either side of the vaginal opening; internally, they are beneath the labia majora. The anterior sections of the bulbs unite to create the bulbar commissure, which forms a long strip of erectile tissue dubbed the infra-corporeal residual spongy part (RSP) that expands from the ventral shaft and terminates as the glans.
Sources: en.wikipedia.org
In tandem mass spectrometry in space, the separation elements are physically separated and distinct, although there is a physical connection between the elements to maintain high vacuum. These elements can be sectors, transmission quadrupole, or time-of-flight. When using multiple quadrupoles, they can act as both mass analyzers and collision chambers. Common notation for mass analyzers is Q – quadrupole mass analyzer; q – radio frequency collision quadrupole; TOF – time-of-flight mass analyzer; B – magnetic sector, and E – electric sector. The notation can be combined to indicate various hybrid instrument, for example QqQ' – triple quadrupole mass spectrometer; QTOF – quadrupole time-of-flight mass spectrometer (also QqTOF); and BEBE – four-sector (reverse geometry) mass spectrometer.
Ammonia (as ammonium) is then excreted predominantly as urea, synthesised in the liver. Transamination can thus be linked to deamination, effectively allowing nitrogen from the amine groups of amino acids to be removed, via glutamate as an intermediate, and finally excreted from the body in the form of urea. Glutamate is also a neurotransmitter (see below), which makes it one of the most abundant molecules in the brain. Malignant brain tumors known as glioma or glioblastoma exploit this phenomenon by using glutamate as an energy source, especially when these tumors become more dependent on glutamate due to mutations in the gene IDH1.
As early as 520 BCE, Jain philosophy, a non-creationist philosophy based on the teachings of Mahavira, stated that the universe and its constituents such as matter cannot be destroyed or created. The Jain text Tattvarthasutra (2nd century CE) states that a substance is permanent, but its modes are characterised by creation and destruction. An important idea in ancient Greek philosophy was that "Nothing comes from nothing", so that what exists now has always existed: no new matter can come into existence where there was none before. An explicit statement of this, along with the further principle that nothing can pass away into nothing, is found in Empedocles (c. 4th century BCE): "For it is impossible for anything to come to be from what is not, and it cannot be brought about or heard of that what is should be utterly destroyed." A further principle of conservation was stated by Epicurus around the 3rd century BCE, who wrote in describing the nature of the Universe that "the totality of things was always such as it is now, and always will be".
Thus, many different specimens may be required to produce a thorough plate for identification of a given species. Accurate colour measurements using spectrometry are possible from specimens. For seabirds, museum specimens are adequate proxies for feather colour but not for skin colour. Bird collections have been useful for retrospective studies. Bird collections offer the potential for current and future researchers to make in-depth morphological and molecular study of past avian diversity. One of the earliest and most famous examples of this was the use of egg collections from the 19th and early 20th centuries in determining that the pesticide DDT was producing eggshell-thinning in raptors. The ornithologists who collected the eggs could never have known that their work would one day help establish causes for declines and help in making conservation strategies to save bird such as peregrine falcons from possible extinction. As threats to bird populations grow and extinctions continue, historical specimens are valuable in documenting the impacts of human activities and causes of decline for threatened species. Bird collections have also been used to gauge the flow of environmental pollutants over time. A study of soot deposits on specimens collected within the United States Manufacturing Belt was used to track concentrations of atmospheric black carbon over a 135-year span. Other possible uses for bird specimens not known today may arise in the future.
Sources: en.wikipedia.org
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.
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.
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.
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.