This is a working overview of melanotan-2, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-12-01. Anything still debated is marked as such rather than presented as settled.
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.
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 II is a synthetic cyclic heptapeptide that acts as an agonist at melanocortin receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide involved in pigment production. The analogue carries a lactam bridge that constrains the ring and slows enzymatic breakdown relative to the native hormone. In research literature it appears under several abbreviations, and naming conventions are not fully standardized. Published descriptions usually place it within the broader melanocortin agonist family.
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.
| 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 |
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.
Published human data come mostly from small, short studies rather than large controlled trials. Reported outcomes include increased skin pigmentation and, in some reports, effects on appetite and libido, but sample sizes are small and follow-up is limited. Whether long-term use produces durable pigment changes or adverse effects is not established. Because products sold outside pharmacies are not standardized, the actual content of any given vial is often unknown. Independent testing of such material is uncommon.
Melanotan II is a synthetic cyclic heptapeptide analog derived from the core sequence of alpha-melanocyte-stimulating hormone. Researchers at the University of Arizona synthesized it during the 1980s while studying pigmentation and appetite signaling. The compound is not an approved medicine in any major jurisdiction and appears mainly in laboratory and research-chemical settings. Its structure incorporates a lactam bridge between side chains, which constrains the ring and slows enzymatic breakdown relative to the natural hormone.
== Education == Gokhan Okan was born on 2 March 1972 in Istanbul. He earned his medical degree from the Istanbul University Cerrahpasa faculty of medicine in 1994. He completed his dermatology residency in 1998 at Istanbul University Istanbul Medical Faculty.
== Synthesis == Shortly after Merck initiated research into reducing the severity and likelihood of chemotherapy-induced nausea and vomiting, researchers discovered that aprepitant is effective in prevention. Researchers worked on coming up with a process to create aprepitant, and within a short period they came up with effective synthesis of the substance. This original synthesis was deemed to be workable and proved to be a crucial step in achieving commercialization; however, Merck decided that the process was not environmentally sustainable. This was due to the original synthesis requiring six steps, many of which needed dangerous chemicals such as sodium cyanide, dimethyltitanocene, and gaseous ammonia. In addition to this, for the process to be effective cryogenic temperatures were needed for some of the steps and other steps produced hazardous byproducts such as methane. The environmental concerns of the synthesis of aprepitant became so great that Merck research team decided to withdraw the drug from clinical trials and attempt to create a different synthesis of aprepitant. The gamble of taking the drug out of clinical trials proved to be successful when shortly afterwards the team of Merck researchers came up with an alternative and more environmentally friendly synthesis of aprepitant. The new process works by four compounds of similar size and complexity being fused together. This therefore is a much simpler process and requires only three steps, half the number of the original synthesis.
=== Elimination === Bicalutamide is eliminated in feces (43%) and urine (34%), whereas its metabolites are eliminated in approximately equal proportions in urine and bile. It is excreted to a substantial extent in its unmetabolized form, with both bicalutamide and its metabolites excreted mainly as glucuronide conjugates.
To determine the equilibrium constant for this reaction, in which the ligand loses a proton, the pKa of the protonated ligand must be known. In practice, the ligand may be polyprotic; for example EDTA4− can accept four protons; in that case, all pKa values must be known. In addition, the metal ion is subject to hydrolysis, that is, it behaves as a weak acid, so the pK values for the hydrolysis reactions must also be known. Assessing the hazard associated with an acid or base may require a knowledge of pKa values. For example, hydrogen cyanide is a very toxic gas, because the cyanide ion inhibits the iron-containing enzyme cytochrome c oxidase. Hydrogen cyanide is a weak acid in aqueous solution with a pKa of about 9. In strongly alkaline solutions, above pH 11, say, it follows that sodium cyanide is "fully dissociated" so the hazard due to the hydrogen cyanide gas is much reduced. An acidic solution, on the other hand, is very hazardous because all the cyanide is in its acid form. Ingestion of cyanide by mouth is potentially fatal, independently of pH, because of the reaction with cytochrome c oxidase. In environmental science acid–base equilibria are important for lakes and rivers; for example, humic acids are important components of natural waters. Another example occurs in chemical oceanography: in order to quantify the solubility of iron(III) in seawater at various salinities, the pKa values for the formation of the iron(III) hydrolysis products Fe(OH)2+, Fe(OH)+2 and Fe(OH)3 were determined, along with the solubility product of iron hydroxide.
== Signs and symptoms == Arthritis entails inflammation within the joint, and presents as swelling, pain, stiffness and restricted joint movement. Symptoms of JIA vary. This is because JIA has several subtypes, which differ according to the number of affected joints, severity of disease, age of onset, prognosis and presence or absence of inflammation in other parts of the body. The key clinical feature in JIA is persistent swelling of the affected joints. Any joint can be affected, but large joints such as the knee and ankle are most commonly involved. Involvement of small joints of the hands and feet is more likely when many joints are affected ('polyarthritis'). Swollen joints may also feel warmer to touch. Swelling may be difficult to detect clinically, especially for joints such as those of the spine, sacroiliac joints, shoulder, hip, and jaw. Joint pain is an important symptom, although some children experience minimal or no pain with their arthritis. In these children, the first sign of arthritis may be limping, especially in the morning. Swelling and pain usually result in limited movement of the affected joints, for example a knee held bent causing a limp, or being unable to make a full fist. Limited movement may reduce a child's ability to fully participate in activities and undertake usual tasks such as those used for self-care. In some JIA subtypes, more non-specific symptoms of being unwell may be present, such as lethargy, fatigue and poor appetite. Children with systemic JIA usually present with fever and a classic rash and may become quite ill.
Sources: en.wikipedia.org
== Career == In 2001, Burke started a tenure track role as an assistant professor at St. Francis Xavier University in 2001, and was promoted to associate professor with Tenure in 2004. In 2008, he left his academia career to start his first business. He applied his research to create a new line of sports nutrition products encompassing protein powders, energy capsules, and muscle-enhancing supplements tailored for professional athletes. In 2013 his company, Rivalus was acquired by Nutrivo. In 2017, Burke started working on a sustainable technology to decrease food waste and conserve nutrients in fruits and vegetables which would have otherwise been discarded. In 2018, he partnered with former NHL hockey player TJ Galiardi to launch Outcast Foods which is a sustainable technology-based company aimed at upcycling discarded fruits and vegetables bound for landfills. He served as the CEO of Outcast Foods till the end of 2021. In the same year he received the EY Entrepreneur of the Year for Atlantic Canada. Burke returned to academia in 2023 as an Industry Professor at McMaster University to help the university set up a makerspace and develop a curriculum for Entrepreneurship and Innovation.
=== British government stance === The British government's refusal to grant independence to Southern Rhodesia under the 1961 constitution was largely the result of the geopolitical and moral shifts associated with the Wind of Change, coupled with the UK's wish to avoid opprobrium and loss of prestige in the United Nations (UN) and the Commonwealth. The issue gained international attention in Africa and worldwide as a flashpoint for questions of decolonisation and racism. By the early 1960s, general consensus in the post-colonial UN—particularly the General Assembly, where the communist bloc and the Afro-Asian lobby were collectively very strong—roundly denounced all forms of colonialism, and supported communist-backed black nationalist insurgencies across southern Africa, regarding them as racial liberation movements. Amid the Cold War, Britain opposed the spread of Soviet and Chinese influence into Africa, but knew it would become an international pariah if it publicly expressed reservations or backed down on NIBMAR in the Southern Rhodesia question. Once the topic of Southern Rhodesia came to the fore in the UN and other bodies, particularly the Organisation of African Unity (OAU), even maintaining the status quo became regarded as unacceptable internationally, causing the UK government a great deal of embarrassment. In the Commonwealth context, too, Britain knew that simply granting independence to Southern Rhodesia was out of the question as many of the Afro-Asian countries were also Commonwealth members.
Brown adipose tissue (BAT) or brown fat makes up the adipose organ together with white adipose tissue (or white fat). Brown adipose tissue is found in almost all mammals. Classification of brown fat refers to two distinct cell populations with similar functions. The first shares a common embryological origin with muscle cells, found in larger "classic" deposits. The second develops from white adipocytes that are stimulated by the sympathetic nervous system. These adipocytes are found interspersed in white adipose tissue and are also named 'beige' or 'brite' (for "brown in white"). Brown adipose tissue is especially abundant in newborns and in hibernating mammals. It is also present and metabolically active in adult humans, but its prevalence decreases as humans age. Its primary function is thermoregulation. In addition to heat produced by shivering muscle, brown adipose tissue produces heat by non-shivering thermogenesis. The therapeutic targeting of brown fat for the treatment of human obesity is an active research field. In contrast to white adipocytes, which contain a single lipid droplet, brown adipocytes contain numerous smaller droplets and a much higher number of (iron-containing) mitochondria, which gives the tissue its color. Brown fat also contains more capillaries than white fat. These supply the tissue with oxygen and nutrients and distribute the produced heat throughout the body. It can now be detected using imaging techniques like positron emission tomography and computed tomography (PET-CT).
=== Young adult and teenage users === Worldwide, increasing numbers of young people are vaping. With access to e-cigarettes, young people's tobacco use has dropped by about 75%. Most young e-cigarette users have never smoked, but there is a substantial minority who both vape and smoke. Many young people who would not smoke are vaping. Young people who smoke tobacco or marijuana, or who drink alcohol, are much more likely to vape. Among young people who have tried vaping, most used a flavored product the first time. Vaping correlates with smoking among young people, even in those who would otherwise be unlikely to smoke. In the U.S., among young people, e-cigarette use increased rapidly in the late 2010s, peaked in 2019, and had fallen substantially by 2024 (7.8% in high school students and 3.5% in middle school students). During that period, the FDA also expanded enforcement activity against unauthorized e-cigarette products. Despite these declines, e-cigarettes remained the most commonly used tobacco product among US youth for the 11th consecutive year in 2024, while cigarette smoking reached historically low levels (1.4% current use). Compared to e-cigarettes, conventional cigarette use had fallen to 1.7% among high school students and 1.1% among middle school students, the lowest prevalence recorded by the survey, according to the 2024 NYTS. Among young people who used e-cigarettes in 2024, 26.3% reported daily use and 87.6% used flavored products, with fruit flavors being the most common.
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.
It is a synthetic cyclic heptapeptide and a non-selective melanocortin receptor agonist. Structurally it is modelled on alpha-melanocyte-stimulating hormone, a peptide that occurs naturally in the body.